forked from OSchip/llvm-project
6951 lines
259 KiB
C++
6951 lines
259 KiB
C++
//===- CodeGenPrepare.cpp - Prepare a function for code generation --------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This pass munges the code in the input function to better prepare it for
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// SelectionDAG-based code generation. This works around limitations in it's
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// basic-block-at-a-time approach. It should eventually be removed.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/ADT/APInt.h"
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#include "llvm/ADT/ArrayRef.h"
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#include "llvm/ADT/DenseMap.h"
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#include "llvm/ADT/PointerIntPair.h"
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#include "llvm/ADT/STLExtras.h"
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#include "llvm/ADT/SmallPtrSet.h"
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#include "llvm/ADT/SmallVector.h"
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#include "llvm/ADT/Statistic.h"
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#include "llvm/Analysis/BlockFrequencyInfo.h"
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#include "llvm/Analysis/BranchProbabilityInfo.h"
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#include "llvm/Analysis/ConstantFolding.h"
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#include "llvm/Analysis/InstructionSimplify.h"
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#include "llvm/Analysis/LoopInfo.h"
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#include "llvm/Analysis/MemoryBuiltins.h"
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#include "llvm/Analysis/ProfileSummaryInfo.h"
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#include "llvm/Analysis/TargetLibraryInfo.h"
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#include "llvm/Analysis/TargetTransformInfo.h"
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#include "llvm/Transforms/Utils/Local.h"
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#include "llvm/Analysis/ValueTracking.h"
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#include "llvm/CodeGen/Analysis.h"
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#include "llvm/CodeGen/ISDOpcodes.h"
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#include "llvm/CodeGen/SelectionDAGNodes.h"
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#include "llvm/CodeGen/TargetLowering.h"
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#include "llvm/CodeGen/TargetPassConfig.h"
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#include "llvm/CodeGen/TargetSubtargetInfo.h"
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#include "llvm/CodeGen/ValueTypes.h"
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#include "llvm/Config/llvm-config.h"
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#include "llvm/IR/Argument.h"
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#include "llvm/IR/Attributes.h"
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#include "llvm/IR/BasicBlock.h"
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#include "llvm/IR/CallSite.h"
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#include "llvm/IR/Constant.h"
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#include "llvm/IR/Constants.h"
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#include "llvm/IR/DataLayout.h"
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#include "llvm/IR/DerivedTypes.h"
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#include "llvm/IR/Dominators.h"
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#include "llvm/IR/Function.h"
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#include "llvm/IR/GetElementPtrTypeIterator.h"
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#include "llvm/IR/GlobalValue.h"
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#include "llvm/IR/GlobalVariable.h"
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#include "llvm/IR/IRBuilder.h"
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#include "llvm/IR/InlineAsm.h"
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#include "llvm/IR/InstrTypes.h"
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#include "llvm/IR/Instruction.h"
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#include "llvm/IR/Instructions.h"
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#include "llvm/IR/IntrinsicInst.h"
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#include "llvm/IR/Intrinsics.h"
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#include "llvm/IR/LLVMContext.h"
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#include "llvm/IR/MDBuilder.h"
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#include "llvm/IR/Module.h"
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#include "llvm/IR/Operator.h"
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#include "llvm/IR/PatternMatch.h"
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#include "llvm/IR/Statepoint.h"
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#include "llvm/IR/Type.h"
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#include "llvm/IR/Use.h"
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#include "llvm/IR/User.h"
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#include "llvm/IR/Value.h"
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#include "llvm/IR/ValueHandle.h"
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#include "llvm/IR/ValueMap.h"
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#include "llvm/Pass.h"
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#include "llvm/Support/BlockFrequency.h"
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#include "llvm/Support/BranchProbability.h"
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#include "llvm/Support/Casting.h"
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#include "llvm/Support/CommandLine.h"
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#include "llvm/Support/Compiler.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/ErrorHandling.h"
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#include "llvm/Support/MachineValueType.h"
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#include "llvm/Support/MathExtras.h"
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#include "llvm/Support/raw_ostream.h"
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#include "llvm/Target/TargetMachine.h"
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#include "llvm/Target/TargetOptions.h"
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#include "llvm/Transforms/Utils/BasicBlockUtils.h"
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#include "llvm/Transforms/Utils/BypassSlowDivision.h"
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#include "llvm/Transforms/Utils/SimplifyLibCalls.h"
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#include <algorithm>
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#include <cassert>
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#include <cstdint>
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#include <iterator>
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#include <limits>
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#include <memory>
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#include <utility>
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#include <vector>
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using namespace llvm;
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using namespace llvm::PatternMatch;
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#define DEBUG_TYPE "codegenprepare"
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STATISTIC(NumBlocksElim, "Number of blocks eliminated");
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STATISTIC(NumPHIsElim, "Number of trivial PHIs eliminated");
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STATISTIC(NumGEPsElim, "Number of GEPs converted to casts");
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STATISTIC(NumCmpUses, "Number of uses of Cmp expressions replaced with uses of "
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"sunken Cmps");
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STATISTIC(NumCastUses, "Number of uses of Cast expressions replaced with uses "
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"of sunken Casts");
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STATISTIC(NumMemoryInsts, "Number of memory instructions whose address "
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"computations were sunk");
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STATISTIC(NumMemoryInstsPhiCreated,
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"Number of phis created when address "
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"computations were sunk to memory instructions");
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STATISTIC(NumMemoryInstsSelectCreated,
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"Number of select created when address "
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"computations were sunk to memory instructions");
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STATISTIC(NumExtsMoved, "Number of [s|z]ext instructions combined with loads");
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STATISTIC(NumExtUses, "Number of uses of [s|z]ext instructions optimized");
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STATISTIC(NumAndsAdded,
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"Number of and mask instructions added to form ext loads");
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STATISTIC(NumAndUses, "Number of uses of and mask instructions optimized");
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STATISTIC(NumRetsDup, "Number of return instructions duplicated");
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STATISTIC(NumDbgValueMoved, "Number of debug value instructions moved");
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STATISTIC(NumSelectsExpanded, "Number of selects turned into branches");
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STATISTIC(NumStoreExtractExposed, "Number of store(extractelement) exposed");
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static cl::opt<bool> DisableBranchOpts(
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"disable-cgp-branch-opts", cl::Hidden, cl::init(false),
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cl::desc("Disable branch optimizations in CodeGenPrepare"));
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static cl::opt<bool>
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DisableGCOpts("disable-cgp-gc-opts", cl::Hidden, cl::init(false),
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cl::desc("Disable GC optimizations in CodeGenPrepare"));
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static cl::opt<bool> DisableSelectToBranch(
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"disable-cgp-select2branch", cl::Hidden, cl::init(false),
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cl::desc("Disable select to branch conversion."));
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static cl::opt<bool> AddrSinkUsingGEPs(
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"addr-sink-using-gep", cl::Hidden, cl::init(true),
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cl::desc("Address sinking in CGP using GEPs."));
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static cl::opt<bool> EnableAndCmpSinking(
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"enable-andcmp-sinking", cl::Hidden, cl::init(true),
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cl::desc("Enable sinkinig and/cmp into branches."));
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static cl::opt<bool> DisableStoreExtract(
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"disable-cgp-store-extract", cl::Hidden, cl::init(false),
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cl::desc("Disable store(extract) optimizations in CodeGenPrepare"));
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static cl::opt<bool> StressStoreExtract(
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"stress-cgp-store-extract", cl::Hidden, cl::init(false),
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cl::desc("Stress test store(extract) optimizations in CodeGenPrepare"));
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static cl::opt<bool> DisableExtLdPromotion(
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"disable-cgp-ext-ld-promotion", cl::Hidden, cl::init(false),
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cl::desc("Disable ext(promotable(ld)) -> promoted(ext(ld)) optimization in "
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"CodeGenPrepare"));
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static cl::opt<bool> StressExtLdPromotion(
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"stress-cgp-ext-ld-promotion", cl::Hidden, cl::init(false),
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cl::desc("Stress test ext(promotable(ld)) -> promoted(ext(ld)) "
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"optimization in CodeGenPrepare"));
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static cl::opt<bool> DisablePreheaderProtect(
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"disable-preheader-prot", cl::Hidden, cl::init(false),
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cl::desc("Disable protection against removing loop preheaders"));
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static cl::opt<bool> ProfileGuidedSectionPrefix(
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"profile-guided-section-prefix", cl::Hidden, cl::init(true), cl::ZeroOrMore,
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cl::desc("Use profile info to add section prefix for hot/cold functions"));
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static cl::opt<unsigned> FreqRatioToSkipMerge(
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"cgp-freq-ratio-to-skip-merge", cl::Hidden, cl::init(2),
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cl::desc("Skip merging empty blocks if (frequency of empty block) / "
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"(frequency of destination block) is greater than this ratio"));
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static cl::opt<bool> ForceSplitStore(
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"force-split-store", cl::Hidden, cl::init(false),
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cl::desc("Force store splitting no matter what the target query says."));
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static cl::opt<bool>
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EnableTypePromotionMerge("cgp-type-promotion-merge", cl::Hidden,
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cl::desc("Enable merging of redundant sexts when one is dominating"
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" the other."), cl::init(true));
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static cl::opt<bool> DisableComplexAddrModes(
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"disable-complex-addr-modes", cl::Hidden, cl::init(false),
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cl::desc("Disables combining addressing modes with different parts "
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"in optimizeMemoryInst."));
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static cl::opt<bool>
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AddrSinkNewPhis("addr-sink-new-phis", cl::Hidden, cl::init(false),
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cl::desc("Allow creation of Phis in Address sinking."));
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static cl::opt<bool>
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AddrSinkNewSelects("addr-sink-new-select", cl::Hidden, cl::init(true),
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cl::desc("Allow creation of selects in Address sinking."));
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static cl::opt<bool> AddrSinkCombineBaseReg(
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"addr-sink-combine-base-reg", cl::Hidden, cl::init(true),
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cl::desc("Allow combining of BaseReg field in Address sinking."));
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static cl::opt<bool> AddrSinkCombineBaseGV(
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"addr-sink-combine-base-gv", cl::Hidden, cl::init(true),
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cl::desc("Allow combining of BaseGV field in Address sinking."));
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static cl::opt<bool> AddrSinkCombineBaseOffs(
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"addr-sink-combine-base-offs", cl::Hidden, cl::init(true),
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cl::desc("Allow combining of BaseOffs field in Address sinking."));
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static cl::opt<bool> AddrSinkCombineScaledReg(
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"addr-sink-combine-scaled-reg", cl::Hidden, cl::init(true),
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cl::desc("Allow combining of ScaledReg field in Address sinking."));
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static cl::opt<bool>
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EnableGEPOffsetSplit("cgp-split-large-offset-gep", cl::Hidden,
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cl::init(true),
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cl::desc("Enable splitting large offset of GEP."));
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namespace {
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enum ExtType {
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ZeroExtension, // Zero extension has been seen.
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SignExtension, // Sign extension has been seen.
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BothExtension // This extension type is used if we saw sext after
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// ZeroExtension had been set, or if we saw zext after
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// SignExtension had been set. It makes the type
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// information of a promoted instruction invalid.
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};
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using SetOfInstrs = SmallPtrSet<Instruction *, 16>;
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using TypeIsSExt = PointerIntPair<Type *, 2, ExtType>;
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using InstrToOrigTy = DenseMap<Instruction *, TypeIsSExt>;
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using SExts = SmallVector<Instruction *, 16>;
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using ValueToSExts = DenseMap<Value *, SExts>;
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class TypePromotionTransaction;
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class CodeGenPrepare : public FunctionPass {
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const TargetMachine *TM = nullptr;
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const TargetSubtargetInfo *SubtargetInfo;
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const TargetLowering *TLI = nullptr;
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const TargetRegisterInfo *TRI;
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const TargetTransformInfo *TTI = nullptr;
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const TargetLibraryInfo *TLInfo;
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const LoopInfo *LI;
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std::unique_ptr<BlockFrequencyInfo> BFI;
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std::unique_ptr<BranchProbabilityInfo> BPI;
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/// As we scan instructions optimizing them, this is the next instruction
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/// to optimize. Transforms that can invalidate this should update it.
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BasicBlock::iterator CurInstIterator;
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/// Keeps track of non-local addresses that have been sunk into a block.
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/// This allows us to avoid inserting duplicate code for blocks with
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/// multiple load/stores of the same address. The usage of WeakTrackingVH
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/// enables SunkAddrs to be treated as a cache whose entries can be
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/// invalidated if a sunken address computation has been erased.
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ValueMap<Value*, WeakTrackingVH> SunkAddrs;
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/// Keeps track of all instructions inserted for the current function.
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SetOfInstrs InsertedInsts;
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/// Keeps track of the type of the related instruction before their
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/// promotion for the current function.
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InstrToOrigTy PromotedInsts;
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/// Keep track of instructions removed during promotion.
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SetOfInstrs RemovedInsts;
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/// Keep track of sext chains based on their initial value.
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DenseMap<Value *, Instruction *> SeenChainsForSExt;
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/// Keep track of GEPs accessing the same data structures such as structs or
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/// arrays that are candidates to be split later because of their large
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/// size.
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MapVector<
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AssertingVH<Value>,
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SmallVector<std::pair<AssertingVH<GetElementPtrInst>, int64_t>, 32>>
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LargeOffsetGEPMap;
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/// Keep track of new GEP base after splitting the GEPs having large offset.
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SmallSet<AssertingVH<Value>, 2> NewGEPBases;
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/// Map serial numbers to Large offset GEPs.
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DenseMap<AssertingVH<GetElementPtrInst>, int> LargeOffsetGEPID;
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/// Keep track of SExt promoted.
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ValueToSExts ValToSExtendedUses;
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/// True if CFG is modified in any way.
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bool ModifiedDT;
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/// True if optimizing for size.
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bool OptSize;
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/// DataLayout for the Function being processed.
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const DataLayout *DL = nullptr;
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public:
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static char ID; // Pass identification, replacement for typeid
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CodeGenPrepare() : FunctionPass(ID) {
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initializeCodeGenPreparePass(*PassRegistry::getPassRegistry());
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}
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bool runOnFunction(Function &F) override;
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StringRef getPassName() const override { return "CodeGen Prepare"; }
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void getAnalysisUsage(AnalysisUsage &AU) const override {
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// FIXME: When we can selectively preserve passes, preserve the domtree.
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AU.addRequired<ProfileSummaryInfoWrapperPass>();
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AU.addRequired<TargetLibraryInfoWrapperPass>();
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AU.addRequired<TargetTransformInfoWrapperPass>();
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AU.addRequired<LoopInfoWrapperPass>();
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}
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private:
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bool eliminateFallThrough(Function &F);
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bool eliminateMostlyEmptyBlocks(Function &F);
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BasicBlock *findDestBlockOfMergeableEmptyBlock(BasicBlock *BB);
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bool canMergeBlocks(const BasicBlock *BB, const BasicBlock *DestBB) const;
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void eliminateMostlyEmptyBlock(BasicBlock *BB);
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bool isMergingEmptyBlockProfitable(BasicBlock *BB, BasicBlock *DestBB,
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bool isPreheader);
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bool optimizeBlock(BasicBlock &BB, bool &ModifiedDT);
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bool optimizeInst(Instruction *I, bool &ModifiedDT);
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bool optimizeMemoryInst(Instruction *MemoryInst, Value *Addr,
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Type *AccessTy, unsigned AddrSpace);
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bool optimizeInlineAsmInst(CallInst *CS);
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bool optimizeCallInst(CallInst *CI, bool &ModifiedDT);
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bool optimizeExt(Instruction *&I);
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bool optimizeExtUses(Instruction *I);
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bool optimizeLoadExt(LoadInst *Load);
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bool optimizeSelectInst(SelectInst *SI);
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bool optimizeShuffleVectorInst(ShuffleVectorInst *SVI);
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bool optimizeSwitchInst(SwitchInst *SI);
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bool optimizeExtractElementInst(Instruction *Inst);
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bool dupRetToEnableTailCallOpts(BasicBlock *BB);
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bool placeDbgValues(Function &F);
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bool canFormExtLd(const SmallVectorImpl<Instruction *> &MovedExts,
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LoadInst *&LI, Instruction *&Inst, bool HasPromoted);
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bool tryToPromoteExts(TypePromotionTransaction &TPT,
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const SmallVectorImpl<Instruction *> &Exts,
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SmallVectorImpl<Instruction *> &ProfitablyMovedExts,
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unsigned CreatedInstsCost = 0);
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bool mergeSExts(Function &F);
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bool splitLargeGEPOffsets();
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bool performAddressTypePromotion(
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Instruction *&Inst,
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bool AllowPromotionWithoutCommonHeader,
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bool HasPromoted, TypePromotionTransaction &TPT,
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SmallVectorImpl<Instruction *> &SpeculativelyMovedExts);
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bool splitBranchCondition(Function &F);
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bool simplifyOffsetableRelocate(Instruction &I);
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};
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} // end anonymous namespace
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char CodeGenPrepare::ID = 0;
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INITIALIZE_PASS_BEGIN(CodeGenPrepare, DEBUG_TYPE,
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"Optimize for code generation", false, false)
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INITIALIZE_PASS_DEPENDENCY(ProfileSummaryInfoWrapperPass)
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INITIALIZE_PASS_END(CodeGenPrepare, DEBUG_TYPE,
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"Optimize for code generation", false, false)
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FunctionPass *llvm::createCodeGenPreparePass() { return new CodeGenPrepare(); }
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bool CodeGenPrepare::runOnFunction(Function &F) {
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if (skipFunction(F))
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return false;
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DL = &F.getParent()->getDataLayout();
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bool EverMadeChange = false;
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// Clear per function information.
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InsertedInsts.clear();
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PromotedInsts.clear();
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ModifiedDT = false;
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if (auto *TPC = getAnalysisIfAvailable<TargetPassConfig>()) {
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TM = &TPC->getTM<TargetMachine>();
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SubtargetInfo = TM->getSubtargetImpl(F);
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TLI = SubtargetInfo->getTargetLowering();
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TRI = SubtargetInfo->getRegisterInfo();
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}
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TLInfo = &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
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TTI = &getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);
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LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
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BPI.reset(new BranchProbabilityInfo(F, *LI));
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BFI.reset(new BlockFrequencyInfo(F, *BPI, *LI));
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OptSize = F.optForSize();
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ProfileSummaryInfo *PSI =
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getAnalysis<ProfileSummaryInfoWrapperPass>().getPSI();
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if (ProfileGuidedSectionPrefix) {
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if (PSI->isFunctionHotInCallGraph(&F, *BFI))
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F.setSectionPrefix(".hot");
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else if (PSI->isFunctionColdInCallGraph(&F, *BFI))
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F.setSectionPrefix(".unlikely");
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}
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/// This optimization identifies DIV instructions that can be
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/// profitably bypassed and carried out with a shorter, faster divide.
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if (!OptSize && !PSI->hasHugeWorkingSetSize() && TLI &&
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TLI->isSlowDivBypassed()) {
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const DenseMap<unsigned int, unsigned int> &BypassWidths =
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TLI->getBypassSlowDivWidths();
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BasicBlock* BB = &*F.begin();
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while (BB != nullptr) {
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// bypassSlowDivision may create new BBs, but we don't want to reapply the
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// optimization to those blocks.
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BasicBlock* Next = BB->getNextNode();
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EverMadeChange |= bypassSlowDivision(BB, BypassWidths);
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BB = Next;
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}
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}
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// Eliminate blocks that contain only PHI nodes and an
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// unconditional branch.
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EverMadeChange |= eliminateMostlyEmptyBlocks(F);
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if (!DisableBranchOpts)
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EverMadeChange |= splitBranchCondition(F);
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// Split some critical edges where one of the sources is an indirect branch,
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// to help generate sane code for PHIs involving such edges.
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EverMadeChange |= SplitIndirectBrCriticalEdges(F);
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bool MadeChange = true;
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while (MadeChange) {
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MadeChange = false;
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SeenChainsForSExt.clear();
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ValToSExtendedUses.clear();
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RemovedInsts.clear();
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LargeOffsetGEPMap.clear();
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LargeOffsetGEPID.clear();
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for (Function::iterator I = F.begin(); I != F.end(); ) {
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BasicBlock *BB = &*I++;
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|
bool ModifiedDTOnIteration = false;
|
|
MadeChange |= optimizeBlock(*BB, ModifiedDTOnIteration);
|
|
|
|
// Restart BB iteration if the dominator tree of the Function was changed
|
|
if (ModifiedDTOnIteration)
|
|
break;
|
|
}
|
|
if (EnableTypePromotionMerge && !ValToSExtendedUses.empty())
|
|
MadeChange |= mergeSExts(F);
|
|
if (!LargeOffsetGEPMap.empty())
|
|
MadeChange |= splitLargeGEPOffsets();
|
|
|
|
// Really free removed instructions during promotion.
|
|
for (Instruction *I : RemovedInsts)
|
|
I->deleteValue();
|
|
|
|
EverMadeChange |= MadeChange;
|
|
}
|
|
|
|
SunkAddrs.clear();
|
|
|
|
if (!DisableBranchOpts) {
|
|
MadeChange = false;
|
|
// Use a set vector to get deterministic iteration order. The order the
|
|
// blocks are removed may affect whether or not PHI nodes in successors
|
|
// are removed.
|
|
SmallSetVector<BasicBlock*, 8> WorkList;
|
|
for (BasicBlock &BB : F) {
|
|
SmallVector<BasicBlock *, 2> Successors(succ_begin(&BB), succ_end(&BB));
|
|
MadeChange |= ConstantFoldTerminator(&BB, true);
|
|
if (!MadeChange) continue;
|
|
|
|
for (SmallVectorImpl<BasicBlock*>::iterator
|
|
II = Successors.begin(), IE = Successors.end(); II != IE; ++II)
|
|
if (pred_begin(*II) == pred_end(*II))
|
|
WorkList.insert(*II);
|
|
}
|
|
|
|
// Delete the dead blocks and any of their dead successors.
|
|
MadeChange |= !WorkList.empty();
|
|
while (!WorkList.empty()) {
|
|
BasicBlock *BB = WorkList.pop_back_val();
|
|
SmallVector<BasicBlock*, 2> Successors(succ_begin(BB), succ_end(BB));
|
|
|
|
DeleteDeadBlock(BB);
|
|
|
|
for (SmallVectorImpl<BasicBlock*>::iterator
|
|
II = Successors.begin(), IE = Successors.end(); II != IE; ++II)
|
|
if (pred_begin(*II) == pred_end(*II))
|
|
WorkList.insert(*II);
|
|
}
|
|
|
|
// Merge pairs of basic blocks with unconditional branches, connected by
|
|
// a single edge.
|
|
if (EverMadeChange || MadeChange)
|
|
MadeChange |= eliminateFallThrough(F);
|
|
|
|
EverMadeChange |= MadeChange;
|
|
}
|
|
|
|
if (!DisableGCOpts) {
|
|
SmallVector<Instruction *, 2> Statepoints;
|
|
for (BasicBlock &BB : F)
|
|
for (Instruction &I : BB)
|
|
if (isStatepoint(I))
|
|
Statepoints.push_back(&I);
|
|
for (auto &I : Statepoints)
|
|
EverMadeChange |= simplifyOffsetableRelocate(*I);
|
|
}
|
|
|
|
// Do this last to clean up use-before-def scenarios introduced by other
|
|
// preparatory transforms.
|
|
EverMadeChange |= placeDbgValues(F);
|
|
|
|
return EverMadeChange;
|
|
}
|
|
|
|
/// Merge basic blocks which are connected by a single edge, where one of the
|
|
/// basic blocks has a single successor pointing to the other basic block,
|
|
/// which has a single predecessor.
|
|
bool CodeGenPrepare::eliminateFallThrough(Function &F) {
|
|
bool Changed = false;
|
|
// Scan all of the blocks in the function, except for the entry block.
|
|
// Use a temporary array to avoid iterator being invalidated when
|
|
// deleting blocks.
|
|
SmallVector<WeakTrackingVH, 16> Blocks;
|
|
for (auto &Block : llvm::make_range(std::next(F.begin()), F.end()))
|
|
Blocks.push_back(&Block);
|
|
|
|
for (auto &Block : Blocks) {
|
|
auto *BB = cast_or_null<BasicBlock>(Block);
|
|
if (!BB)
|
|
continue;
|
|
// If the destination block has a single pred, then this is a trivial
|
|
// edge, just collapse it.
|
|
BasicBlock *SinglePred = BB->getSinglePredecessor();
|
|
|
|
// Don't merge if BB's address is taken.
|
|
if (!SinglePred || SinglePred == BB || BB->hasAddressTaken()) continue;
|
|
|
|
BranchInst *Term = dyn_cast<BranchInst>(SinglePred->getTerminator());
|
|
if (Term && !Term->isConditional()) {
|
|
Changed = true;
|
|
LLVM_DEBUG(dbgs() << "To merge:\n" << *BB << "\n\n\n");
|
|
|
|
// Merge BB into SinglePred and delete it.
|
|
MergeBlockIntoPredecessor(BB);
|
|
}
|
|
}
|
|
return Changed;
|
|
}
|
|
|
|
/// Find a destination block from BB if BB is mergeable empty block.
|
|
BasicBlock *CodeGenPrepare::findDestBlockOfMergeableEmptyBlock(BasicBlock *BB) {
|
|
// If this block doesn't end with an uncond branch, ignore it.
|
|
BranchInst *BI = dyn_cast<BranchInst>(BB->getTerminator());
|
|
if (!BI || !BI->isUnconditional())
|
|
return nullptr;
|
|
|
|
// If the instruction before the branch (skipping debug info) isn't a phi
|
|
// node, then other stuff is happening here.
|
|
BasicBlock::iterator BBI = BI->getIterator();
|
|
if (BBI != BB->begin()) {
|
|
--BBI;
|
|
while (isa<DbgInfoIntrinsic>(BBI)) {
|
|
if (BBI == BB->begin())
|
|
break;
|
|
--BBI;
|
|
}
|
|
if (!isa<DbgInfoIntrinsic>(BBI) && !isa<PHINode>(BBI))
|
|
return nullptr;
|
|
}
|
|
|
|
// Do not break infinite loops.
|
|
BasicBlock *DestBB = BI->getSuccessor(0);
|
|
if (DestBB == BB)
|
|
return nullptr;
|
|
|
|
if (!canMergeBlocks(BB, DestBB))
|
|
DestBB = nullptr;
|
|
|
|
return DestBB;
|
|
}
|
|
|
|
/// Eliminate blocks that contain only PHI nodes, debug info directives, and an
|
|
/// unconditional branch. Passes before isel (e.g. LSR/loopsimplify) often split
|
|
/// edges in ways that are non-optimal for isel. Start by eliminating these
|
|
/// blocks so we can split them the way we want them.
|
|
bool CodeGenPrepare::eliminateMostlyEmptyBlocks(Function &F) {
|
|
SmallPtrSet<BasicBlock *, 16> Preheaders;
|
|
SmallVector<Loop *, 16> LoopList(LI->begin(), LI->end());
|
|
while (!LoopList.empty()) {
|
|
Loop *L = LoopList.pop_back_val();
|
|
LoopList.insert(LoopList.end(), L->begin(), L->end());
|
|
if (BasicBlock *Preheader = L->getLoopPreheader())
|
|
Preheaders.insert(Preheader);
|
|
}
|
|
|
|
bool MadeChange = false;
|
|
// Copy blocks into a temporary array to avoid iterator invalidation issues
|
|
// as we remove them.
|
|
// Note that this intentionally skips the entry block.
|
|
SmallVector<WeakTrackingVH, 16> Blocks;
|
|
for (auto &Block : llvm::make_range(std::next(F.begin()), F.end()))
|
|
Blocks.push_back(&Block);
|
|
|
|
for (auto &Block : Blocks) {
|
|
BasicBlock *BB = cast_or_null<BasicBlock>(Block);
|
|
if (!BB)
|
|
continue;
|
|
BasicBlock *DestBB = findDestBlockOfMergeableEmptyBlock(BB);
|
|
if (!DestBB ||
|
|
!isMergingEmptyBlockProfitable(BB, DestBB, Preheaders.count(BB)))
|
|
continue;
|
|
|
|
eliminateMostlyEmptyBlock(BB);
|
|
MadeChange = true;
|
|
}
|
|
return MadeChange;
|
|
}
|
|
|
|
bool CodeGenPrepare::isMergingEmptyBlockProfitable(BasicBlock *BB,
|
|
BasicBlock *DestBB,
|
|
bool isPreheader) {
|
|
// Do not delete loop preheaders if doing so would create a critical edge.
|
|
// Loop preheaders can be good locations to spill registers. If the
|
|
// preheader is deleted and we create a critical edge, registers may be
|
|
// spilled in the loop body instead.
|
|
if (!DisablePreheaderProtect && isPreheader &&
|
|
!(BB->getSinglePredecessor() &&
|
|
BB->getSinglePredecessor()->getSingleSuccessor()))
|
|
return false;
|
|
|
|
// Try to skip merging if the unique predecessor of BB is terminated by a
|
|
// switch or indirect branch instruction, and BB is used as an incoming block
|
|
// of PHIs in DestBB. In such case, merging BB and DestBB would cause ISel to
|
|
// add COPY instructions in the predecessor of BB instead of BB (if it is not
|
|
// merged). Note that the critical edge created by merging such blocks wont be
|
|
// split in MachineSink because the jump table is not analyzable. By keeping
|
|
// such empty block (BB), ISel will place COPY instructions in BB, not in the
|
|
// predecessor of BB.
|
|
BasicBlock *Pred = BB->getUniquePredecessor();
|
|
if (!Pred ||
|
|
!(isa<SwitchInst>(Pred->getTerminator()) ||
|
|
isa<IndirectBrInst>(Pred->getTerminator())))
|
|
return true;
|
|
|
|
if (BB->getTerminator() != BB->getFirstNonPHIOrDbg())
|
|
return true;
|
|
|
|
// We use a simple cost heuristic which determine skipping merging is
|
|
// profitable if the cost of skipping merging is less than the cost of
|
|
// merging : Cost(skipping merging) < Cost(merging BB), where the
|
|
// Cost(skipping merging) is Freq(BB) * (Cost(Copy) + Cost(Branch)), and
|
|
// the Cost(merging BB) is Freq(Pred) * Cost(Copy).
|
|
// Assuming Cost(Copy) == Cost(Branch), we could simplify it to :
|
|
// Freq(Pred) / Freq(BB) > 2.
|
|
// Note that if there are multiple empty blocks sharing the same incoming
|
|
// value for the PHIs in the DestBB, we consider them together. In such
|
|
// case, Cost(merging BB) will be the sum of their frequencies.
|
|
|
|
if (!isa<PHINode>(DestBB->begin()))
|
|
return true;
|
|
|
|
SmallPtrSet<BasicBlock *, 16> SameIncomingValueBBs;
|
|
|
|
// Find all other incoming blocks from which incoming values of all PHIs in
|
|
// DestBB are the same as the ones from BB.
|
|
for (pred_iterator PI = pred_begin(DestBB), E = pred_end(DestBB); PI != E;
|
|
++PI) {
|
|
BasicBlock *DestBBPred = *PI;
|
|
if (DestBBPred == BB)
|
|
continue;
|
|
|
|
if (llvm::all_of(DestBB->phis(), [&](const PHINode &DestPN) {
|
|
return DestPN.getIncomingValueForBlock(BB) ==
|
|
DestPN.getIncomingValueForBlock(DestBBPred);
|
|
}))
|
|
SameIncomingValueBBs.insert(DestBBPred);
|
|
}
|
|
|
|
// See if all BB's incoming values are same as the value from Pred. In this
|
|
// case, no reason to skip merging because COPYs are expected to be place in
|
|
// Pred already.
|
|
if (SameIncomingValueBBs.count(Pred))
|
|
return true;
|
|
|
|
BlockFrequency PredFreq = BFI->getBlockFreq(Pred);
|
|
BlockFrequency BBFreq = BFI->getBlockFreq(BB);
|
|
|
|
for (auto SameValueBB : SameIncomingValueBBs)
|
|
if (SameValueBB->getUniquePredecessor() == Pred &&
|
|
DestBB == findDestBlockOfMergeableEmptyBlock(SameValueBB))
|
|
BBFreq += BFI->getBlockFreq(SameValueBB);
|
|
|
|
return PredFreq.getFrequency() <=
|
|
BBFreq.getFrequency() * FreqRatioToSkipMerge;
|
|
}
|
|
|
|
/// Return true if we can merge BB into DestBB if there is a single
|
|
/// unconditional branch between them, and BB contains no other non-phi
|
|
/// instructions.
|
|
bool CodeGenPrepare::canMergeBlocks(const BasicBlock *BB,
|
|
const BasicBlock *DestBB) const {
|
|
// We only want to eliminate blocks whose phi nodes are used by phi nodes in
|
|
// the successor. If there are more complex condition (e.g. preheaders),
|
|
// don't mess around with them.
|
|
for (const PHINode &PN : BB->phis()) {
|
|
for (const User *U : PN.users()) {
|
|
const Instruction *UI = cast<Instruction>(U);
|
|
if (UI->getParent() != DestBB || !isa<PHINode>(UI))
|
|
return false;
|
|
// If User is inside DestBB block and it is a PHINode then check
|
|
// incoming value. If incoming value is not from BB then this is
|
|
// a complex condition (e.g. preheaders) we want to avoid here.
|
|
if (UI->getParent() == DestBB) {
|
|
if (const PHINode *UPN = dyn_cast<PHINode>(UI))
|
|
for (unsigned I = 0, E = UPN->getNumIncomingValues(); I != E; ++I) {
|
|
Instruction *Insn = dyn_cast<Instruction>(UPN->getIncomingValue(I));
|
|
if (Insn && Insn->getParent() == BB &&
|
|
Insn->getParent() != UPN->getIncomingBlock(I))
|
|
return false;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// If BB and DestBB contain any common predecessors, then the phi nodes in BB
|
|
// and DestBB may have conflicting incoming values for the block. If so, we
|
|
// can't merge the block.
|
|
const PHINode *DestBBPN = dyn_cast<PHINode>(DestBB->begin());
|
|
if (!DestBBPN) return true; // no conflict.
|
|
|
|
// Collect the preds of BB.
|
|
SmallPtrSet<const BasicBlock*, 16> BBPreds;
|
|
if (const PHINode *BBPN = dyn_cast<PHINode>(BB->begin())) {
|
|
// It is faster to get preds from a PHI than with pred_iterator.
|
|
for (unsigned i = 0, e = BBPN->getNumIncomingValues(); i != e; ++i)
|
|
BBPreds.insert(BBPN->getIncomingBlock(i));
|
|
} else {
|
|
BBPreds.insert(pred_begin(BB), pred_end(BB));
|
|
}
|
|
|
|
// Walk the preds of DestBB.
|
|
for (unsigned i = 0, e = DestBBPN->getNumIncomingValues(); i != e; ++i) {
|
|
BasicBlock *Pred = DestBBPN->getIncomingBlock(i);
|
|
if (BBPreds.count(Pred)) { // Common predecessor?
|
|
for (const PHINode &PN : DestBB->phis()) {
|
|
const Value *V1 = PN.getIncomingValueForBlock(Pred);
|
|
const Value *V2 = PN.getIncomingValueForBlock(BB);
|
|
|
|
// If V2 is a phi node in BB, look up what the mapped value will be.
|
|
if (const PHINode *V2PN = dyn_cast<PHINode>(V2))
|
|
if (V2PN->getParent() == BB)
|
|
V2 = V2PN->getIncomingValueForBlock(Pred);
|
|
|
|
// If there is a conflict, bail out.
|
|
if (V1 != V2) return false;
|
|
}
|
|
}
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
/// Eliminate a basic block that has only phi's and an unconditional branch in
|
|
/// it.
|
|
void CodeGenPrepare::eliminateMostlyEmptyBlock(BasicBlock *BB) {
|
|
BranchInst *BI = cast<BranchInst>(BB->getTerminator());
|
|
BasicBlock *DestBB = BI->getSuccessor(0);
|
|
|
|
LLVM_DEBUG(dbgs() << "MERGING MOSTLY EMPTY BLOCKS - BEFORE:\n"
|
|
<< *BB << *DestBB);
|
|
|
|
// If the destination block has a single pred, then this is a trivial edge,
|
|
// just collapse it.
|
|
if (BasicBlock *SinglePred = DestBB->getSinglePredecessor()) {
|
|
if (SinglePred != DestBB) {
|
|
assert(SinglePred == BB &&
|
|
"Single predecessor not the same as predecessor");
|
|
// Merge DestBB into SinglePred/BB and delete it.
|
|
MergeBlockIntoPredecessor(DestBB);
|
|
// Note: BB(=SinglePred) will not be deleted on this path.
|
|
// DestBB(=its single successor) is the one that was deleted.
|
|
LLVM_DEBUG(dbgs() << "AFTER:\n" << *SinglePred << "\n\n\n");
|
|
return;
|
|
}
|
|
}
|
|
|
|
// Otherwise, we have multiple predecessors of BB. Update the PHIs in DestBB
|
|
// to handle the new incoming edges it is about to have.
|
|
for (PHINode &PN : DestBB->phis()) {
|
|
// Remove the incoming value for BB, and remember it.
|
|
Value *InVal = PN.removeIncomingValue(BB, false);
|
|
|
|
// Two options: either the InVal is a phi node defined in BB or it is some
|
|
// value that dominates BB.
|
|
PHINode *InValPhi = dyn_cast<PHINode>(InVal);
|
|
if (InValPhi && InValPhi->getParent() == BB) {
|
|
// Add all of the input values of the input PHI as inputs of this phi.
|
|
for (unsigned i = 0, e = InValPhi->getNumIncomingValues(); i != e; ++i)
|
|
PN.addIncoming(InValPhi->getIncomingValue(i),
|
|
InValPhi->getIncomingBlock(i));
|
|
} else {
|
|
// Otherwise, add one instance of the dominating value for each edge that
|
|
// we will be adding.
|
|
if (PHINode *BBPN = dyn_cast<PHINode>(BB->begin())) {
|
|
for (unsigned i = 0, e = BBPN->getNumIncomingValues(); i != e; ++i)
|
|
PN.addIncoming(InVal, BBPN->getIncomingBlock(i));
|
|
} else {
|
|
for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI)
|
|
PN.addIncoming(InVal, *PI);
|
|
}
|
|
}
|
|
}
|
|
|
|
// The PHIs are now updated, change everything that refers to BB to use
|
|
// DestBB and remove BB.
|
|
BB->replaceAllUsesWith(DestBB);
|
|
BB->eraseFromParent();
|
|
++NumBlocksElim;
|
|
|
|
LLVM_DEBUG(dbgs() << "AFTER:\n" << *DestBB << "\n\n\n");
|
|
}
|
|
|
|
// Computes a map of base pointer relocation instructions to corresponding
|
|
// derived pointer relocation instructions given a vector of all relocate calls
|
|
static void computeBaseDerivedRelocateMap(
|
|
const SmallVectorImpl<GCRelocateInst *> &AllRelocateCalls,
|
|
DenseMap<GCRelocateInst *, SmallVector<GCRelocateInst *, 2>>
|
|
&RelocateInstMap) {
|
|
// Collect information in two maps: one primarily for locating the base object
|
|
// while filling the second map; the second map is the final structure holding
|
|
// a mapping between Base and corresponding Derived relocate calls
|
|
DenseMap<std::pair<unsigned, unsigned>, GCRelocateInst *> RelocateIdxMap;
|
|
for (auto *ThisRelocate : AllRelocateCalls) {
|
|
auto K = std::make_pair(ThisRelocate->getBasePtrIndex(),
|
|
ThisRelocate->getDerivedPtrIndex());
|
|
RelocateIdxMap.insert(std::make_pair(K, ThisRelocate));
|
|
}
|
|
for (auto &Item : RelocateIdxMap) {
|
|
std::pair<unsigned, unsigned> Key = Item.first;
|
|
if (Key.first == Key.second)
|
|
// Base relocation: nothing to insert
|
|
continue;
|
|
|
|
GCRelocateInst *I = Item.second;
|
|
auto BaseKey = std::make_pair(Key.first, Key.first);
|
|
|
|
// We're iterating over RelocateIdxMap so we cannot modify it.
|
|
auto MaybeBase = RelocateIdxMap.find(BaseKey);
|
|
if (MaybeBase == RelocateIdxMap.end())
|
|
// TODO: We might want to insert a new base object relocate and gep off
|
|
// that, if there are enough derived object relocates.
|
|
continue;
|
|
|
|
RelocateInstMap[MaybeBase->second].push_back(I);
|
|
}
|
|
}
|
|
|
|
// Accepts a GEP and extracts the operands into a vector provided they're all
|
|
// small integer constants
|
|
static bool getGEPSmallConstantIntOffsetV(GetElementPtrInst *GEP,
|
|
SmallVectorImpl<Value *> &OffsetV) {
|
|
for (unsigned i = 1; i < GEP->getNumOperands(); i++) {
|
|
// Only accept small constant integer operands
|
|
auto Op = dyn_cast<ConstantInt>(GEP->getOperand(i));
|
|
if (!Op || Op->getZExtValue() > 20)
|
|
return false;
|
|
}
|
|
|
|
for (unsigned i = 1; i < GEP->getNumOperands(); i++)
|
|
OffsetV.push_back(GEP->getOperand(i));
|
|
return true;
|
|
}
|
|
|
|
// Takes a RelocatedBase (base pointer relocation instruction) and Targets to
|
|
// replace, computes a replacement, and affects it.
|
|
static bool
|
|
simplifyRelocatesOffABase(GCRelocateInst *RelocatedBase,
|
|
const SmallVectorImpl<GCRelocateInst *> &Targets) {
|
|
bool MadeChange = false;
|
|
// We must ensure the relocation of derived pointer is defined after
|
|
// relocation of base pointer. If we find a relocation corresponding to base
|
|
// defined earlier than relocation of base then we move relocation of base
|
|
// right before found relocation. We consider only relocation in the same
|
|
// basic block as relocation of base. Relocations from other basic block will
|
|
// be skipped by optimization and we do not care about them.
|
|
for (auto R = RelocatedBase->getParent()->getFirstInsertionPt();
|
|
&*R != RelocatedBase; ++R)
|
|
if (auto RI = dyn_cast<GCRelocateInst>(R))
|
|
if (RI->getStatepoint() == RelocatedBase->getStatepoint())
|
|
if (RI->getBasePtrIndex() == RelocatedBase->getBasePtrIndex()) {
|
|
RelocatedBase->moveBefore(RI);
|
|
break;
|
|
}
|
|
|
|
for (GCRelocateInst *ToReplace : Targets) {
|
|
assert(ToReplace->getBasePtrIndex() == RelocatedBase->getBasePtrIndex() &&
|
|
"Not relocating a derived object of the original base object");
|
|
if (ToReplace->getBasePtrIndex() == ToReplace->getDerivedPtrIndex()) {
|
|
// A duplicate relocate call. TODO: coalesce duplicates.
|
|
continue;
|
|
}
|
|
|
|
if (RelocatedBase->getParent() != ToReplace->getParent()) {
|
|
// Base and derived relocates are in different basic blocks.
|
|
// In this case transform is only valid when base dominates derived
|
|
// relocate. However it would be too expensive to check dominance
|
|
// for each such relocate, so we skip the whole transformation.
|
|
continue;
|
|
}
|
|
|
|
Value *Base = ToReplace->getBasePtr();
|
|
auto Derived = dyn_cast<GetElementPtrInst>(ToReplace->getDerivedPtr());
|
|
if (!Derived || Derived->getPointerOperand() != Base)
|
|
continue;
|
|
|
|
SmallVector<Value *, 2> OffsetV;
|
|
if (!getGEPSmallConstantIntOffsetV(Derived, OffsetV))
|
|
continue;
|
|
|
|
// Create a Builder and replace the target callsite with a gep
|
|
assert(RelocatedBase->getNextNode() &&
|
|
"Should always have one since it's not a terminator");
|
|
|
|
// Insert after RelocatedBase
|
|
IRBuilder<> Builder(RelocatedBase->getNextNode());
|
|
Builder.SetCurrentDebugLocation(ToReplace->getDebugLoc());
|
|
|
|
// If gc_relocate does not match the actual type, cast it to the right type.
|
|
// In theory, there must be a bitcast after gc_relocate if the type does not
|
|
// match, and we should reuse it to get the derived pointer. But it could be
|
|
// cases like this:
|
|
// bb1:
|
|
// ...
|
|
// %g1 = call coldcc i8 addrspace(1)* @llvm.experimental.gc.relocate.p1i8(...)
|
|
// br label %merge
|
|
//
|
|
// bb2:
|
|
// ...
|
|
// %g2 = call coldcc i8 addrspace(1)* @llvm.experimental.gc.relocate.p1i8(...)
|
|
// br label %merge
|
|
//
|
|
// merge:
|
|
// %p1 = phi i8 addrspace(1)* [ %g1, %bb1 ], [ %g2, %bb2 ]
|
|
// %cast = bitcast i8 addrspace(1)* %p1 in to i32 addrspace(1)*
|
|
//
|
|
// In this case, we can not find the bitcast any more. So we insert a new bitcast
|
|
// no matter there is already one or not. In this way, we can handle all cases, and
|
|
// the extra bitcast should be optimized away in later passes.
|
|
Value *ActualRelocatedBase = RelocatedBase;
|
|
if (RelocatedBase->getType() != Base->getType()) {
|
|
ActualRelocatedBase =
|
|
Builder.CreateBitCast(RelocatedBase, Base->getType());
|
|
}
|
|
Value *Replacement = Builder.CreateGEP(
|
|
Derived->getSourceElementType(), ActualRelocatedBase, makeArrayRef(OffsetV));
|
|
Replacement->takeName(ToReplace);
|
|
// If the newly generated derived pointer's type does not match the original derived
|
|
// pointer's type, cast the new derived pointer to match it. Same reasoning as above.
|
|
Value *ActualReplacement = Replacement;
|
|
if (Replacement->getType() != ToReplace->getType()) {
|
|
ActualReplacement =
|
|
Builder.CreateBitCast(Replacement, ToReplace->getType());
|
|
}
|
|
ToReplace->replaceAllUsesWith(ActualReplacement);
|
|
ToReplace->eraseFromParent();
|
|
|
|
MadeChange = true;
|
|
}
|
|
return MadeChange;
|
|
}
|
|
|
|
// Turns this:
|
|
//
|
|
// %base = ...
|
|
// %ptr = gep %base + 15
|
|
// %tok = statepoint (%fun, i32 0, i32 0, i32 0, %base, %ptr)
|
|
// %base' = relocate(%tok, i32 4, i32 4)
|
|
// %ptr' = relocate(%tok, i32 4, i32 5)
|
|
// %val = load %ptr'
|
|
//
|
|
// into this:
|
|
//
|
|
// %base = ...
|
|
// %ptr = gep %base + 15
|
|
// %tok = statepoint (%fun, i32 0, i32 0, i32 0, %base, %ptr)
|
|
// %base' = gc.relocate(%tok, i32 4, i32 4)
|
|
// %ptr' = gep %base' + 15
|
|
// %val = load %ptr'
|
|
bool CodeGenPrepare::simplifyOffsetableRelocate(Instruction &I) {
|
|
bool MadeChange = false;
|
|
SmallVector<GCRelocateInst *, 2> AllRelocateCalls;
|
|
|
|
for (auto *U : I.users())
|
|
if (GCRelocateInst *Relocate = dyn_cast<GCRelocateInst>(U))
|
|
// Collect all the relocate calls associated with a statepoint
|
|
AllRelocateCalls.push_back(Relocate);
|
|
|
|
// We need atleast one base pointer relocation + one derived pointer
|
|
// relocation to mangle
|
|
if (AllRelocateCalls.size() < 2)
|
|
return false;
|
|
|
|
// RelocateInstMap is a mapping from the base relocate instruction to the
|
|
// corresponding derived relocate instructions
|
|
DenseMap<GCRelocateInst *, SmallVector<GCRelocateInst *, 2>> RelocateInstMap;
|
|
computeBaseDerivedRelocateMap(AllRelocateCalls, RelocateInstMap);
|
|
if (RelocateInstMap.empty())
|
|
return false;
|
|
|
|
for (auto &Item : RelocateInstMap)
|
|
// Item.first is the RelocatedBase to offset against
|
|
// Item.second is the vector of Targets to replace
|
|
MadeChange = simplifyRelocatesOffABase(Item.first, Item.second);
|
|
return MadeChange;
|
|
}
|
|
|
|
/// SinkCast - Sink the specified cast instruction into its user blocks
|
|
static bool SinkCast(CastInst *CI) {
|
|
BasicBlock *DefBB = CI->getParent();
|
|
|
|
/// InsertedCasts - Only insert a cast in each block once.
|
|
DenseMap<BasicBlock*, CastInst*> InsertedCasts;
|
|
|
|
bool MadeChange = false;
|
|
for (Value::user_iterator UI = CI->user_begin(), E = CI->user_end();
|
|
UI != E; ) {
|
|
Use &TheUse = UI.getUse();
|
|
Instruction *User = cast<Instruction>(*UI);
|
|
|
|
// Figure out which BB this cast is used in. For PHI's this is the
|
|
// appropriate predecessor block.
|
|
BasicBlock *UserBB = User->getParent();
|
|
if (PHINode *PN = dyn_cast<PHINode>(User)) {
|
|
UserBB = PN->getIncomingBlock(TheUse);
|
|
}
|
|
|
|
// Preincrement use iterator so we don't invalidate it.
|
|
++UI;
|
|
|
|
// The first insertion point of a block containing an EH pad is after the
|
|
// pad. If the pad is the user, we cannot sink the cast past the pad.
|
|
if (User->isEHPad())
|
|
continue;
|
|
|
|
// If the block selected to receive the cast is an EH pad that does not
|
|
// allow non-PHI instructions before the terminator, we can't sink the
|
|
// cast.
|
|
if (UserBB->getTerminator()->isEHPad())
|
|
continue;
|
|
|
|
// If this user is in the same block as the cast, don't change the cast.
|
|
if (UserBB == DefBB) continue;
|
|
|
|
// If we have already inserted a cast into this block, use it.
|
|
CastInst *&InsertedCast = InsertedCasts[UserBB];
|
|
|
|
if (!InsertedCast) {
|
|
BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
|
|
assert(InsertPt != UserBB->end());
|
|
InsertedCast = CastInst::Create(CI->getOpcode(), CI->getOperand(0),
|
|
CI->getType(), "", &*InsertPt);
|
|
InsertedCast->setDebugLoc(CI->getDebugLoc());
|
|
}
|
|
|
|
// Replace a use of the cast with a use of the new cast.
|
|
TheUse = InsertedCast;
|
|
MadeChange = true;
|
|
++NumCastUses;
|
|
}
|
|
|
|
// If we removed all uses, nuke the cast.
|
|
if (CI->use_empty()) {
|
|
salvageDebugInfo(*CI);
|
|
CI->eraseFromParent();
|
|
MadeChange = true;
|
|
}
|
|
|
|
return MadeChange;
|
|
}
|
|
|
|
/// If the specified cast instruction is a noop copy (e.g. it's casting from
|
|
/// one pointer type to another, i32->i8 on PPC), sink it into user blocks to
|
|
/// reduce the number of virtual registers that must be created and coalesced.
|
|
///
|
|
/// Return true if any changes are made.
|
|
static bool OptimizeNoopCopyExpression(CastInst *CI, const TargetLowering &TLI,
|
|
const DataLayout &DL) {
|
|
// Sink only "cheap" (or nop) address-space casts. This is a weaker condition
|
|
// than sinking only nop casts, but is helpful on some platforms.
|
|
if (auto *ASC = dyn_cast<AddrSpaceCastInst>(CI)) {
|
|
if (!TLI.isCheapAddrSpaceCast(ASC->getSrcAddressSpace(),
|
|
ASC->getDestAddressSpace()))
|
|
return false;
|
|
}
|
|
|
|
// If this is a noop copy,
|
|
EVT SrcVT = TLI.getValueType(DL, CI->getOperand(0)->getType());
|
|
EVT DstVT = TLI.getValueType(DL, CI->getType());
|
|
|
|
// This is an fp<->int conversion?
|
|
if (SrcVT.isInteger() != DstVT.isInteger())
|
|
return false;
|
|
|
|
// If this is an extension, it will be a zero or sign extension, which
|
|
// isn't a noop.
|
|
if (SrcVT.bitsLT(DstVT)) return false;
|
|
|
|
// If these values will be promoted, find out what they will be promoted
|
|
// to. This helps us consider truncates on PPC as noop copies when they
|
|
// are.
|
|
if (TLI.getTypeAction(CI->getContext(), SrcVT) ==
|
|
TargetLowering::TypePromoteInteger)
|
|
SrcVT = TLI.getTypeToTransformTo(CI->getContext(), SrcVT);
|
|
if (TLI.getTypeAction(CI->getContext(), DstVT) ==
|
|
TargetLowering::TypePromoteInteger)
|
|
DstVT = TLI.getTypeToTransformTo(CI->getContext(), DstVT);
|
|
|
|
// If, after promotion, these are the same types, this is a noop copy.
|
|
if (SrcVT != DstVT)
|
|
return false;
|
|
|
|
return SinkCast(CI);
|
|
}
|
|
|
|
/// Try to combine CI into a call to the llvm.uadd.with.overflow intrinsic if
|
|
/// possible.
|
|
///
|
|
/// Return true if any changes were made.
|
|
static bool CombineUAddWithOverflow(CmpInst *CI) {
|
|
Value *A, *B;
|
|
Instruction *AddI;
|
|
if (!match(CI,
|
|
m_UAddWithOverflow(m_Value(A), m_Value(B), m_Instruction(AddI))))
|
|
return false;
|
|
|
|
Type *Ty = AddI->getType();
|
|
if (!isa<IntegerType>(Ty))
|
|
return false;
|
|
|
|
// We don't want to move around uses of condition values this late, so we we
|
|
// check if it is legal to create the call to the intrinsic in the basic
|
|
// block containing the icmp:
|
|
|
|
if (AddI->getParent() != CI->getParent() && !AddI->hasOneUse())
|
|
return false;
|
|
|
|
#ifndef NDEBUG
|
|
// Someday m_UAddWithOverflow may get smarter, but this is a safe assumption
|
|
// for now:
|
|
if (AddI->hasOneUse())
|
|
assert(*AddI->user_begin() == CI && "expected!");
|
|
#endif
|
|
|
|
Module *M = CI->getModule();
|
|
Value *F = Intrinsic::getDeclaration(M, Intrinsic::uadd_with_overflow, Ty);
|
|
|
|
auto *InsertPt = AddI->hasOneUse() ? CI : AddI;
|
|
|
|
DebugLoc Loc = CI->getDebugLoc();
|
|
auto *UAddWithOverflow =
|
|
CallInst::Create(F, {A, B}, "uadd.overflow", InsertPt);
|
|
UAddWithOverflow->setDebugLoc(Loc);
|
|
auto *UAdd = ExtractValueInst::Create(UAddWithOverflow, 0, "uadd", InsertPt);
|
|
UAdd->setDebugLoc(Loc);
|
|
auto *Overflow =
|
|
ExtractValueInst::Create(UAddWithOverflow, 1, "overflow", InsertPt);
|
|
Overflow->setDebugLoc(Loc);
|
|
|
|
CI->replaceAllUsesWith(Overflow);
|
|
AddI->replaceAllUsesWith(UAdd);
|
|
CI->eraseFromParent();
|
|
AddI->eraseFromParent();
|
|
return true;
|
|
}
|
|
|
|
/// Sink the given CmpInst into user blocks to reduce the number of virtual
|
|
/// registers that must be created and coalesced. This is a clear win except on
|
|
/// targets with multiple condition code registers (PowerPC), where it might
|
|
/// lose; some adjustment may be wanted there.
|
|
///
|
|
/// Return true if any changes are made.
|
|
static bool SinkCmpExpression(CmpInst *CI, const TargetLowering *TLI) {
|
|
BasicBlock *DefBB = CI->getParent();
|
|
|
|
// Avoid sinking soft-FP comparisons, since this can move them into a loop.
|
|
if (TLI && TLI->useSoftFloat() && isa<FCmpInst>(CI))
|
|
return false;
|
|
|
|
// Only insert a cmp in each block once.
|
|
DenseMap<BasicBlock*, CmpInst*> InsertedCmps;
|
|
|
|
bool MadeChange = false;
|
|
for (Value::user_iterator UI = CI->user_begin(), E = CI->user_end();
|
|
UI != E; ) {
|
|
Use &TheUse = UI.getUse();
|
|
Instruction *User = cast<Instruction>(*UI);
|
|
|
|
// Preincrement use iterator so we don't invalidate it.
|
|
++UI;
|
|
|
|
// Don't bother for PHI nodes.
|
|
if (isa<PHINode>(User))
|
|
continue;
|
|
|
|
// Figure out which BB this cmp is used in.
|
|
BasicBlock *UserBB = User->getParent();
|
|
|
|
// If this user is in the same block as the cmp, don't change the cmp.
|
|
if (UserBB == DefBB) continue;
|
|
|
|
// If we have already inserted a cmp into this block, use it.
|
|
CmpInst *&InsertedCmp = InsertedCmps[UserBB];
|
|
|
|
if (!InsertedCmp) {
|
|
BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
|
|
assert(InsertPt != UserBB->end());
|
|
InsertedCmp =
|
|
CmpInst::Create(CI->getOpcode(), CI->getPredicate(),
|
|
CI->getOperand(0), CI->getOperand(1), "", &*InsertPt);
|
|
// Propagate the debug info.
|
|
InsertedCmp->setDebugLoc(CI->getDebugLoc());
|
|
}
|
|
|
|
// Replace a use of the cmp with a use of the new cmp.
|
|
TheUse = InsertedCmp;
|
|
MadeChange = true;
|
|
++NumCmpUses;
|
|
}
|
|
|
|
// If we removed all uses, nuke the cmp.
|
|
if (CI->use_empty()) {
|
|
CI->eraseFromParent();
|
|
MadeChange = true;
|
|
}
|
|
|
|
return MadeChange;
|
|
}
|
|
|
|
static bool OptimizeCmpExpression(CmpInst *CI, const TargetLowering *TLI) {
|
|
if (SinkCmpExpression(CI, TLI))
|
|
return true;
|
|
|
|
if (CombineUAddWithOverflow(CI))
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
/// Duplicate and sink the given 'and' instruction into user blocks where it is
|
|
/// used in a compare to allow isel to generate better code for targets where
|
|
/// this operation can be combined.
|
|
///
|
|
/// Return true if any changes are made.
|
|
static bool sinkAndCmp0Expression(Instruction *AndI,
|
|
const TargetLowering &TLI,
|
|
SetOfInstrs &InsertedInsts) {
|
|
// Double-check that we're not trying to optimize an instruction that was
|
|
// already optimized by some other part of this pass.
|
|
assert(!InsertedInsts.count(AndI) &&
|
|
"Attempting to optimize already optimized and instruction");
|
|
(void) InsertedInsts;
|
|
|
|
// Nothing to do for single use in same basic block.
|
|
if (AndI->hasOneUse() &&
|
|
AndI->getParent() == cast<Instruction>(*AndI->user_begin())->getParent())
|
|
return false;
|
|
|
|
// Try to avoid cases where sinking/duplicating is likely to increase register
|
|
// pressure.
|
|
if (!isa<ConstantInt>(AndI->getOperand(0)) &&
|
|
!isa<ConstantInt>(AndI->getOperand(1)) &&
|
|
AndI->getOperand(0)->hasOneUse() && AndI->getOperand(1)->hasOneUse())
|
|
return false;
|
|
|
|
for (auto *U : AndI->users()) {
|
|
Instruction *User = cast<Instruction>(U);
|
|
|
|
// Only sink for and mask feeding icmp with 0.
|
|
if (!isa<ICmpInst>(User))
|
|
return false;
|
|
|
|
auto *CmpC = dyn_cast<ConstantInt>(User->getOperand(1));
|
|
if (!CmpC || !CmpC->isZero())
|
|
return false;
|
|
}
|
|
|
|
if (!TLI.isMaskAndCmp0FoldingBeneficial(*AndI))
|
|
return false;
|
|
|
|
LLVM_DEBUG(dbgs() << "found 'and' feeding only icmp 0;\n");
|
|
LLVM_DEBUG(AndI->getParent()->dump());
|
|
|
|
// Push the 'and' into the same block as the icmp 0. There should only be
|
|
// one (icmp (and, 0)) in each block, since CSE/GVN should have removed any
|
|
// others, so we don't need to keep track of which BBs we insert into.
|
|
for (Value::user_iterator UI = AndI->user_begin(), E = AndI->user_end();
|
|
UI != E; ) {
|
|
Use &TheUse = UI.getUse();
|
|
Instruction *User = cast<Instruction>(*UI);
|
|
|
|
// Preincrement use iterator so we don't invalidate it.
|
|
++UI;
|
|
|
|
LLVM_DEBUG(dbgs() << "sinking 'and' use: " << *User << "\n");
|
|
|
|
// Keep the 'and' in the same place if the use is already in the same block.
|
|
Instruction *InsertPt =
|
|
User->getParent() == AndI->getParent() ? AndI : User;
|
|
Instruction *InsertedAnd =
|
|
BinaryOperator::Create(Instruction::And, AndI->getOperand(0),
|
|
AndI->getOperand(1), "", InsertPt);
|
|
// Propagate the debug info.
|
|
InsertedAnd->setDebugLoc(AndI->getDebugLoc());
|
|
|
|
// Replace a use of the 'and' with a use of the new 'and'.
|
|
TheUse = InsertedAnd;
|
|
++NumAndUses;
|
|
LLVM_DEBUG(User->getParent()->dump());
|
|
}
|
|
|
|
// We removed all uses, nuke the and.
|
|
AndI->eraseFromParent();
|
|
return true;
|
|
}
|
|
|
|
/// Check if the candidates could be combined with a shift instruction, which
|
|
/// includes:
|
|
/// 1. Truncate instruction
|
|
/// 2. And instruction and the imm is a mask of the low bits:
|
|
/// imm & (imm+1) == 0
|
|
static bool isExtractBitsCandidateUse(Instruction *User) {
|
|
if (!isa<TruncInst>(User)) {
|
|
if (User->getOpcode() != Instruction::And ||
|
|
!isa<ConstantInt>(User->getOperand(1)))
|
|
return false;
|
|
|
|
const APInt &Cimm = cast<ConstantInt>(User->getOperand(1))->getValue();
|
|
|
|
if ((Cimm & (Cimm + 1)).getBoolValue())
|
|
return false;
|
|
}
|
|
return true;
|
|
}
|
|
|
|
/// Sink both shift and truncate instruction to the use of truncate's BB.
|
|
static bool
|
|
SinkShiftAndTruncate(BinaryOperator *ShiftI, Instruction *User, ConstantInt *CI,
|
|
DenseMap<BasicBlock *, BinaryOperator *> &InsertedShifts,
|
|
const TargetLowering &TLI, const DataLayout &DL) {
|
|
BasicBlock *UserBB = User->getParent();
|
|
DenseMap<BasicBlock *, CastInst *> InsertedTruncs;
|
|
TruncInst *TruncI = dyn_cast<TruncInst>(User);
|
|
bool MadeChange = false;
|
|
|
|
for (Value::user_iterator TruncUI = TruncI->user_begin(),
|
|
TruncE = TruncI->user_end();
|
|
TruncUI != TruncE;) {
|
|
|
|
Use &TruncTheUse = TruncUI.getUse();
|
|
Instruction *TruncUser = cast<Instruction>(*TruncUI);
|
|
// Preincrement use iterator so we don't invalidate it.
|
|
|
|
++TruncUI;
|
|
|
|
int ISDOpcode = TLI.InstructionOpcodeToISD(TruncUser->getOpcode());
|
|
if (!ISDOpcode)
|
|
continue;
|
|
|
|
// If the use is actually a legal node, there will not be an
|
|
// implicit truncate.
|
|
// FIXME: always querying the result type is just an
|
|
// approximation; some nodes' legality is determined by the
|
|
// operand or other means. There's no good way to find out though.
|
|
if (TLI.isOperationLegalOrCustom(
|
|
ISDOpcode, TLI.getValueType(DL, TruncUser->getType(), true)))
|
|
continue;
|
|
|
|
// Don't bother for PHI nodes.
|
|
if (isa<PHINode>(TruncUser))
|
|
continue;
|
|
|
|
BasicBlock *TruncUserBB = TruncUser->getParent();
|
|
|
|
if (UserBB == TruncUserBB)
|
|
continue;
|
|
|
|
BinaryOperator *&InsertedShift = InsertedShifts[TruncUserBB];
|
|
CastInst *&InsertedTrunc = InsertedTruncs[TruncUserBB];
|
|
|
|
if (!InsertedShift && !InsertedTrunc) {
|
|
BasicBlock::iterator InsertPt = TruncUserBB->getFirstInsertionPt();
|
|
assert(InsertPt != TruncUserBB->end());
|
|
// Sink the shift
|
|
if (ShiftI->getOpcode() == Instruction::AShr)
|
|
InsertedShift = BinaryOperator::CreateAShr(ShiftI->getOperand(0), CI,
|
|
"", &*InsertPt);
|
|
else
|
|
InsertedShift = BinaryOperator::CreateLShr(ShiftI->getOperand(0), CI,
|
|
"", &*InsertPt);
|
|
InsertedShift->setDebugLoc(ShiftI->getDebugLoc());
|
|
|
|
// Sink the trunc
|
|
BasicBlock::iterator TruncInsertPt = TruncUserBB->getFirstInsertionPt();
|
|
TruncInsertPt++;
|
|
assert(TruncInsertPt != TruncUserBB->end());
|
|
|
|
InsertedTrunc = CastInst::Create(TruncI->getOpcode(), InsertedShift,
|
|
TruncI->getType(), "", &*TruncInsertPt);
|
|
InsertedTrunc->setDebugLoc(TruncI->getDebugLoc());
|
|
|
|
MadeChange = true;
|
|
|
|
TruncTheUse = InsertedTrunc;
|
|
}
|
|
}
|
|
return MadeChange;
|
|
}
|
|
|
|
/// Sink the shift *right* instruction into user blocks if the uses could
|
|
/// potentially be combined with this shift instruction and generate BitExtract
|
|
/// instruction. It will only be applied if the architecture supports BitExtract
|
|
/// instruction. Here is an example:
|
|
/// BB1:
|
|
/// %x.extract.shift = lshr i64 %arg1, 32
|
|
/// BB2:
|
|
/// %x.extract.trunc = trunc i64 %x.extract.shift to i16
|
|
/// ==>
|
|
///
|
|
/// BB2:
|
|
/// %x.extract.shift.1 = lshr i64 %arg1, 32
|
|
/// %x.extract.trunc = trunc i64 %x.extract.shift.1 to i16
|
|
///
|
|
/// CodeGen will recognize the pattern in BB2 and generate BitExtract
|
|
/// instruction.
|
|
/// Return true if any changes are made.
|
|
static bool OptimizeExtractBits(BinaryOperator *ShiftI, ConstantInt *CI,
|
|
const TargetLowering &TLI,
|
|
const DataLayout &DL) {
|
|
BasicBlock *DefBB = ShiftI->getParent();
|
|
|
|
/// Only insert instructions in each block once.
|
|
DenseMap<BasicBlock *, BinaryOperator *> InsertedShifts;
|
|
|
|
bool shiftIsLegal = TLI.isTypeLegal(TLI.getValueType(DL, ShiftI->getType()));
|
|
|
|
bool MadeChange = false;
|
|
for (Value::user_iterator UI = ShiftI->user_begin(), E = ShiftI->user_end();
|
|
UI != E;) {
|
|
Use &TheUse = UI.getUse();
|
|
Instruction *User = cast<Instruction>(*UI);
|
|
// Preincrement use iterator so we don't invalidate it.
|
|
++UI;
|
|
|
|
// Don't bother for PHI nodes.
|
|
if (isa<PHINode>(User))
|
|
continue;
|
|
|
|
if (!isExtractBitsCandidateUse(User))
|
|
continue;
|
|
|
|
BasicBlock *UserBB = User->getParent();
|
|
|
|
if (UserBB == DefBB) {
|
|
// If the shift and truncate instruction are in the same BB. The use of
|
|
// the truncate(TruncUse) may still introduce another truncate if not
|
|
// legal. In this case, we would like to sink both shift and truncate
|
|
// instruction to the BB of TruncUse.
|
|
// for example:
|
|
// BB1:
|
|
// i64 shift.result = lshr i64 opnd, imm
|
|
// trunc.result = trunc shift.result to i16
|
|
//
|
|
// BB2:
|
|
// ----> We will have an implicit truncate here if the architecture does
|
|
// not have i16 compare.
|
|
// cmp i16 trunc.result, opnd2
|
|
//
|
|
if (isa<TruncInst>(User) && shiftIsLegal
|
|
// If the type of the truncate is legal, no truncate will be
|
|
// introduced in other basic blocks.
|
|
&&
|
|
(!TLI.isTypeLegal(TLI.getValueType(DL, User->getType()))))
|
|
MadeChange =
|
|
SinkShiftAndTruncate(ShiftI, User, CI, InsertedShifts, TLI, DL);
|
|
|
|
continue;
|
|
}
|
|
// If we have already inserted a shift into this block, use it.
|
|
BinaryOperator *&InsertedShift = InsertedShifts[UserBB];
|
|
|
|
if (!InsertedShift) {
|
|
BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
|
|
assert(InsertPt != UserBB->end());
|
|
|
|
if (ShiftI->getOpcode() == Instruction::AShr)
|
|
InsertedShift = BinaryOperator::CreateAShr(ShiftI->getOperand(0), CI,
|
|
"", &*InsertPt);
|
|
else
|
|
InsertedShift = BinaryOperator::CreateLShr(ShiftI->getOperand(0), CI,
|
|
"", &*InsertPt);
|
|
InsertedShift->setDebugLoc(ShiftI->getDebugLoc());
|
|
|
|
MadeChange = true;
|
|
}
|
|
|
|
// Replace a use of the shift with a use of the new shift.
|
|
TheUse = InsertedShift;
|
|
}
|
|
|
|
// If we removed all uses, nuke the shift.
|
|
if (ShiftI->use_empty()) {
|
|
salvageDebugInfo(*ShiftI);
|
|
ShiftI->eraseFromParent();
|
|
}
|
|
|
|
return MadeChange;
|
|
}
|
|
|
|
/// If counting leading or trailing zeros is an expensive operation and a zero
|
|
/// input is defined, add a check for zero to avoid calling the intrinsic.
|
|
///
|
|
/// We want to transform:
|
|
/// %z = call i64 @llvm.cttz.i64(i64 %A, i1 false)
|
|
///
|
|
/// into:
|
|
/// entry:
|
|
/// %cmpz = icmp eq i64 %A, 0
|
|
/// br i1 %cmpz, label %cond.end, label %cond.false
|
|
/// cond.false:
|
|
/// %z = call i64 @llvm.cttz.i64(i64 %A, i1 true)
|
|
/// br label %cond.end
|
|
/// cond.end:
|
|
/// %ctz = phi i64 [ 64, %entry ], [ %z, %cond.false ]
|
|
///
|
|
/// If the transform is performed, return true and set ModifiedDT to true.
|
|
static bool despeculateCountZeros(IntrinsicInst *CountZeros,
|
|
const TargetLowering *TLI,
|
|
const DataLayout *DL,
|
|
bool &ModifiedDT) {
|
|
if (!TLI || !DL)
|
|
return false;
|
|
|
|
// If a zero input is undefined, it doesn't make sense to despeculate that.
|
|
if (match(CountZeros->getOperand(1), m_One()))
|
|
return false;
|
|
|
|
// If it's cheap to speculate, there's nothing to do.
|
|
auto IntrinsicID = CountZeros->getIntrinsicID();
|
|
if ((IntrinsicID == Intrinsic::cttz && TLI->isCheapToSpeculateCttz()) ||
|
|
(IntrinsicID == Intrinsic::ctlz && TLI->isCheapToSpeculateCtlz()))
|
|
return false;
|
|
|
|
// Only handle legal scalar cases. Anything else requires too much work.
|
|
Type *Ty = CountZeros->getType();
|
|
unsigned SizeInBits = Ty->getPrimitiveSizeInBits();
|
|
if (Ty->isVectorTy() || SizeInBits > DL->getLargestLegalIntTypeSizeInBits())
|
|
return false;
|
|
|
|
// The intrinsic will be sunk behind a compare against zero and branch.
|
|
BasicBlock *StartBlock = CountZeros->getParent();
|
|
BasicBlock *CallBlock = StartBlock->splitBasicBlock(CountZeros, "cond.false");
|
|
|
|
// Create another block after the count zero intrinsic. A PHI will be added
|
|
// in this block to select the result of the intrinsic or the bit-width
|
|
// constant if the input to the intrinsic is zero.
|
|
BasicBlock::iterator SplitPt = ++(BasicBlock::iterator(CountZeros));
|
|
BasicBlock *EndBlock = CallBlock->splitBasicBlock(SplitPt, "cond.end");
|
|
|
|
// Set up a builder to create a compare, conditional branch, and PHI.
|
|
IRBuilder<> Builder(CountZeros->getContext());
|
|
Builder.SetInsertPoint(StartBlock->getTerminator());
|
|
Builder.SetCurrentDebugLocation(CountZeros->getDebugLoc());
|
|
|
|
// Replace the unconditional branch that was created by the first split with
|
|
// a compare against zero and a conditional branch.
|
|
Value *Zero = Constant::getNullValue(Ty);
|
|
Value *Cmp = Builder.CreateICmpEQ(CountZeros->getOperand(0), Zero, "cmpz");
|
|
Builder.CreateCondBr(Cmp, EndBlock, CallBlock);
|
|
StartBlock->getTerminator()->eraseFromParent();
|
|
|
|
// Create a PHI in the end block to select either the output of the intrinsic
|
|
// or the bit width of the operand.
|
|
Builder.SetInsertPoint(&EndBlock->front());
|
|
PHINode *PN = Builder.CreatePHI(Ty, 2, "ctz");
|
|
CountZeros->replaceAllUsesWith(PN);
|
|
Value *BitWidth = Builder.getInt(APInt(SizeInBits, SizeInBits));
|
|
PN->addIncoming(BitWidth, StartBlock);
|
|
PN->addIncoming(CountZeros, CallBlock);
|
|
|
|
// We are explicitly handling the zero case, so we can set the intrinsic's
|
|
// undefined zero argument to 'true'. This will also prevent reprocessing the
|
|
// intrinsic; we only despeculate when a zero input is defined.
|
|
CountZeros->setArgOperand(1, Builder.getTrue());
|
|
ModifiedDT = true;
|
|
return true;
|
|
}
|
|
|
|
bool CodeGenPrepare::optimizeCallInst(CallInst *CI, bool &ModifiedDT) {
|
|
BasicBlock *BB = CI->getParent();
|
|
|
|
// Lower inline assembly if we can.
|
|
// If we found an inline asm expession, and if the target knows how to
|
|
// lower it to normal LLVM code, do so now.
|
|
if (TLI && isa<InlineAsm>(CI->getCalledValue())) {
|
|
if (TLI->ExpandInlineAsm(CI)) {
|
|
// Avoid invalidating the iterator.
|
|
CurInstIterator = BB->begin();
|
|
// Avoid processing instructions out of order, which could cause
|
|
// reuse before a value is defined.
|
|
SunkAddrs.clear();
|
|
return true;
|
|
}
|
|
// Sink address computing for memory operands into the block.
|
|
if (optimizeInlineAsmInst(CI))
|
|
return true;
|
|
}
|
|
|
|
// Align the pointer arguments to this call if the target thinks it's a good
|
|
// idea
|
|
unsigned MinSize, PrefAlign;
|
|
if (TLI && TLI->shouldAlignPointerArgs(CI, MinSize, PrefAlign)) {
|
|
for (auto &Arg : CI->arg_operands()) {
|
|
// We want to align both objects whose address is used directly and
|
|
// objects whose address is used in casts and GEPs, though it only makes
|
|
// sense for GEPs if the offset is a multiple of the desired alignment and
|
|
// if size - offset meets the size threshold.
|
|
if (!Arg->getType()->isPointerTy())
|
|
continue;
|
|
APInt Offset(DL->getIndexSizeInBits(
|
|
cast<PointerType>(Arg->getType())->getAddressSpace()),
|
|
0);
|
|
Value *Val = Arg->stripAndAccumulateInBoundsConstantOffsets(*DL, Offset);
|
|
uint64_t Offset2 = Offset.getLimitedValue();
|
|
if ((Offset2 & (PrefAlign-1)) != 0)
|
|
continue;
|
|
AllocaInst *AI;
|
|
if ((AI = dyn_cast<AllocaInst>(Val)) && AI->getAlignment() < PrefAlign &&
|
|
DL->getTypeAllocSize(AI->getAllocatedType()) >= MinSize + Offset2)
|
|
AI->setAlignment(PrefAlign);
|
|
// Global variables can only be aligned if they are defined in this
|
|
// object (i.e. they are uniquely initialized in this object), and
|
|
// over-aligning global variables that have an explicit section is
|
|
// forbidden.
|
|
GlobalVariable *GV;
|
|
if ((GV = dyn_cast<GlobalVariable>(Val)) && GV->canIncreaseAlignment() &&
|
|
GV->getPointerAlignment(*DL) < PrefAlign &&
|
|
DL->getTypeAllocSize(GV->getValueType()) >=
|
|
MinSize + Offset2)
|
|
GV->setAlignment(PrefAlign);
|
|
}
|
|
// If this is a memcpy (or similar) then we may be able to improve the
|
|
// alignment
|
|
if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(CI)) {
|
|
unsigned DestAlign = getKnownAlignment(MI->getDest(), *DL);
|
|
if (DestAlign > MI->getDestAlignment())
|
|
MI->setDestAlignment(DestAlign);
|
|
if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(MI)) {
|
|
unsigned SrcAlign = getKnownAlignment(MTI->getSource(), *DL);
|
|
if (SrcAlign > MTI->getSourceAlignment())
|
|
MTI->setSourceAlignment(SrcAlign);
|
|
}
|
|
}
|
|
}
|
|
|
|
// If we have a cold call site, try to sink addressing computation into the
|
|
// cold block. This interacts with our handling for loads and stores to
|
|
// ensure that we can fold all uses of a potential addressing computation
|
|
// into their uses. TODO: generalize this to work over profiling data
|
|
if (!OptSize && CI->hasFnAttr(Attribute::Cold))
|
|
for (auto &Arg : CI->arg_operands()) {
|
|
if (!Arg->getType()->isPointerTy())
|
|
continue;
|
|
unsigned AS = Arg->getType()->getPointerAddressSpace();
|
|
return optimizeMemoryInst(CI, Arg, Arg->getType(), AS);
|
|
}
|
|
|
|
IntrinsicInst *II = dyn_cast<IntrinsicInst>(CI);
|
|
if (II) {
|
|
switch (II->getIntrinsicID()) {
|
|
default: break;
|
|
case Intrinsic::objectsize: {
|
|
// Lower all uses of llvm.objectsize.*
|
|
ConstantInt *RetVal =
|
|
lowerObjectSizeCall(II, *DL, TLInfo, /*MustSucceed=*/true);
|
|
// Substituting this can cause recursive simplifications, which can
|
|
// invalidate our iterator. Use a WeakTrackingVH to hold onto it in case
|
|
// this
|
|
// happens.
|
|
Value *CurValue = &*CurInstIterator;
|
|
WeakTrackingVH IterHandle(CurValue);
|
|
|
|
replaceAndRecursivelySimplify(CI, RetVal, TLInfo, nullptr);
|
|
|
|
// If the iterator instruction was recursively deleted, start over at the
|
|
// start of the block.
|
|
if (IterHandle != CurValue) {
|
|
CurInstIterator = BB->begin();
|
|
SunkAddrs.clear();
|
|
}
|
|
return true;
|
|
}
|
|
case Intrinsic::aarch64_stlxr:
|
|
case Intrinsic::aarch64_stxr: {
|
|
ZExtInst *ExtVal = dyn_cast<ZExtInst>(CI->getArgOperand(0));
|
|
if (!ExtVal || !ExtVal->hasOneUse() ||
|
|
ExtVal->getParent() == CI->getParent())
|
|
return false;
|
|
// Sink a zext feeding stlxr/stxr before it, so it can be folded into it.
|
|
ExtVal->moveBefore(CI);
|
|
// Mark this instruction as "inserted by CGP", so that other
|
|
// optimizations don't touch it.
|
|
InsertedInsts.insert(ExtVal);
|
|
return true;
|
|
}
|
|
case Intrinsic::launder_invariant_group:
|
|
case Intrinsic::strip_invariant_group:
|
|
II->replaceAllUsesWith(II->getArgOperand(0));
|
|
II->eraseFromParent();
|
|
return true;
|
|
|
|
case Intrinsic::cttz:
|
|
case Intrinsic::ctlz:
|
|
// If counting zeros is expensive, try to avoid it.
|
|
return despeculateCountZeros(II, TLI, DL, ModifiedDT);
|
|
}
|
|
|
|
if (TLI) {
|
|
SmallVector<Value*, 2> PtrOps;
|
|
Type *AccessTy;
|
|
if (TLI->getAddrModeArguments(II, PtrOps, AccessTy))
|
|
while (!PtrOps.empty()) {
|
|
Value *PtrVal = PtrOps.pop_back_val();
|
|
unsigned AS = PtrVal->getType()->getPointerAddressSpace();
|
|
if (optimizeMemoryInst(II, PtrVal, AccessTy, AS))
|
|
return true;
|
|
}
|
|
}
|
|
}
|
|
|
|
// From here on out we're working with named functions.
|
|
if (!CI->getCalledFunction()) return false;
|
|
|
|
// Lower all default uses of _chk calls. This is very similar
|
|
// to what InstCombineCalls does, but here we are only lowering calls
|
|
// to fortified library functions (e.g. __memcpy_chk) that have the default
|
|
// "don't know" as the objectsize. Anything else should be left alone.
|
|
FortifiedLibCallSimplifier Simplifier(TLInfo, true);
|
|
if (Value *V = Simplifier.optimizeCall(CI)) {
|
|
CI->replaceAllUsesWith(V);
|
|
CI->eraseFromParent();
|
|
return true;
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
/// Look for opportunities to duplicate return instructions to the predecessor
|
|
/// to enable tail call optimizations. The case it is currently looking for is:
|
|
/// @code
|
|
/// bb0:
|
|
/// %tmp0 = tail call i32 @f0()
|
|
/// br label %return
|
|
/// bb1:
|
|
/// %tmp1 = tail call i32 @f1()
|
|
/// br label %return
|
|
/// bb2:
|
|
/// %tmp2 = tail call i32 @f2()
|
|
/// br label %return
|
|
/// return:
|
|
/// %retval = phi i32 [ %tmp0, %bb0 ], [ %tmp1, %bb1 ], [ %tmp2, %bb2 ]
|
|
/// ret i32 %retval
|
|
/// @endcode
|
|
///
|
|
/// =>
|
|
///
|
|
/// @code
|
|
/// bb0:
|
|
/// %tmp0 = tail call i32 @f0()
|
|
/// ret i32 %tmp0
|
|
/// bb1:
|
|
/// %tmp1 = tail call i32 @f1()
|
|
/// ret i32 %tmp1
|
|
/// bb2:
|
|
/// %tmp2 = tail call i32 @f2()
|
|
/// ret i32 %tmp2
|
|
/// @endcode
|
|
bool CodeGenPrepare::dupRetToEnableTailCallOpts(BasicBlock *BB) {
|
|
if (!TLI)
|
|
return false;
|
|
|
|
ReturnInst *RetI = dyn_cast<ReturnInst>(BB->getTerminator());
|
|
if (!RetI)
|
|
return false;
|
|
|
|
PHINode *PN = nullptr;
|
|
BitCastInst *BCI = nullptr;
|
|
Value *V = RetI->getReturnValue();
|
|
if (V) {
|
|
BCI = dyn_cast<BitCastInst>(V);
|
|
if (BCI)
|
|
V = BCI->getOperand(0);
|
|
|
|
PN = dyn_cast<PHINode>(V);
|
|
if (!PN)
|
|
return false;
|
|
}
|
|
|
|
if (PN && PN->getParent() != BB)
|
|
return false;
|
|
|
|
// Make sure there are no instructions between the PHI and return, or that the
|
|
// return is the first instruction in the block.
|
|
if (PN) {
|
|
BasicBlock::iterator BI = BB->begin();
|
|
do { ++BI; } while (isa<DbgInfoIntrinsic>(BI));
|
|
if (&*BI == BCI)
|
|
// Also skip over the bitcast.
|
|
++BI;
|
|
if (&*BI != RetI)
|
|
return false;
|
|
} else {
|
|
BasicBlock::iterator BI = BB->begin();
|
|
while (isa<DbgInfoIntrinsic>(BI)) ++BI;
|
|
if (&*BI != RetI)
|
|
return false;
|
|
}
|
|
|
|
/// Only dup the ReturnInst if the CallInst is likely to be emitted as a tail
|
|
/// call.
|
|
const Function *F = BB->getParent();
|
|
SmallVector<CallInst*, 4> TailCalls;
|
|
if (PN) {
|
|
for (unsigned I = 0, E = PN->getNumIncomingValues(); I != E; ++I) {
|
|
CallInst *CI = dyn_cast<CallInst>(PN->getIncomingValue(I));
|
|
// Make sure the phi value is indeed produced by the tail call.
|
|
if (CI && CI->hasOneUse() && CI->getParent() == PN->getIncomingBlock(I) &&
|
|
TLI->mayBeEmittedAsTailCall(CI) &&
|
|
attributesPermitTailCall(F, CI, RetI, *TLI))
|
|
TailCalls.push_back(CI);
|
|
}
|
|
} else {
|
|
SmallPtrSet<BasicBlock*, 4> VisitedBBs;
|
|
for (pred_iterator PI = pred_begin(BB), PE = pred_end(BB); PI != PE; ++PI) {
|
|
if (!VisitedBBs.insert(*PI).second)
|
|
continue;
|
|
|
|
BasicBlock::InstListType &InstList = (*PI)->getInstList();
|
|
BasicBlock::InstListType::reverse_iterator RI = InstList.rbegin();
|
|
BasicBlock::InstListType::reverse_iterator RE = InstList.rend();
|
|
do { ++RI; } while (RI != RE && isa<DbgInfoIntrinsic>(&*RI));
|
|
if (RI == RE)
|
|
continue;
|
|
|
|
CallInst *CI = dyn_cast<CallInst>(&*RI);
|
|
if (CI && CI->use_empty() && TLI->mayBeEmittedAsTailCall(CI) &&
|
|
attributesPermitTailCall(F, CI, RetI, *TLI))
|
|
TailCalls.push_back(CI);
|
|
}
|
|
}
|
|
|
|
bool Changed = false;
|
|
for (unsigned i = 0, e = TailCalls.size(); i != e; ++i) {
|
|
CallInst *CI = TailCalls[i];
|
|
CallSite CS(CI);
|
|
|
|
// Conservatively require the attributes of the call to match those of the
|
|
// return. Ignore noalias because it doesn't affect the call sequence.
|
|
AttributeList CalleeAttrs = CS.getAttributes();
|
|
if (AttrBuilder(CalleeAttrs, AttributeList::ReturnIndex)
|
|
.removeAttribute(Attribute::NoAlias) !=
|
|
AttrBuilder(CalleeAttrs, AttributeList::ReturnIndex)
|
|
.removeAttribute(Attribute::NoAlias))
|
|
continue;
|
|
|
|
// Make sure the call instruction is followed by an unconditional branch to
|
|
// the return block.
|
|
BasicBlock *CallBB = CI->getParent();
|
|
BranchInst *BI = dyn_cast<BranchInst>(CallBB->getTerminator());
|
|
if (!BI || !BI->isUnconditional() || BI->getSuccessor(0) != BB)
|
|
continue;
|
|
|
|
// Duplicate the return into CallBB.
|
|
(void)FoldReturnIntoUncondBranch(RetI, BB, CallBB);
|
|
ModifiedDT = Changed = true;
|
|
++NumRetsDup;
|
|
}
|
|
|
|
// If we eliminated all predecessors of the block, delete the block now.
|
|
if (Changed && !BB->hasAddressTaken() && pred_begin(BB) == pred_end(BB))
|
|
BB->eraseFromParent();
|
|
|
|
return Changed;
|
|
}
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// Memory Optimization
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
namespace {
|
|
|
|
/// This is an extended version of TargetLowering::AddrMode
|
|
/// which holds actual Value*'s for register values.
|
|
struct ExtAddrMode : public TargetLowering::AddrMode {
|
|
Value *BaseReg = nullptr;
|
|
Value *ScaledReg = nullptr;
|
|
Value *OriginalValue = nullptr;
|
|
|
|
enum FieldName {
|
|
NoField = 0x00,
|
|
BaseRegField = 0x01,
|
|
BaseGVField = 0x02,
|
|
BaseOffsField = 0x04,
|
|
ScaledRegField = 0x08,
|
|
ScaleField = 0x10,
|
|
MultipleFields = 0xff
|
|
};
|
|
|
|
ExtAddrMode() = default;
|
|
|
|
void print(raw_ostream &OS) const;
|
|
void dump() const;
|
|
|
|
FieldName compare(const ExtAddrMode &other) {
|
|
// First check that the types are the same on each field, as differing types
|
|
// is something we can't cope with later on.
|
|
if (BaseReg && other.BaseReg &&
|
|
BaseReg->getType() != other.BaseReg->getType())
|
|
return MultipleFields;
|
|
if (BaseGV && other.BaseGV &&
|
|
BaseGV->getType() != other.BaseGV->getType())
|
|
return MultipleFields;
|
|
if (ScaledReg && other.ScaledReg &&
|
|
ScaledReg->getType() != other.ScaledReg->getType())
|
|
return MultipleFields;
|
|
|
|
// Check each field to see if it differs.
|
|
unsigned Result = NoField;
|
|
if (BaseReg != other.BaseReg)
|
|
Result |= BaseRegField;
|
|
if (BaseGV != other.BaseGV)
|
|
Result |= BaseGVField;
|
|
if (BaseOffs != other.BaseOffs)
|
|
Result |= BaseOffsField;
|
|
if (ScaledReg != other.ScaledReg)
|
|
Result |= ScaledRegField;
|
|
// Don't count 0 as being a different scale, because that actually means
|
|
// unscaled (which will already be counted by having no ScaledReg).
|
|
if (Scale && other.Scale && Scale != other.Scale)
|
|
Result |= ScaleField;
|
|
|
|
if (countPopulation(Result) > 1)
|
|
return MultipleFields;
|
|
else
|
|
return static_cast<FieldName>(Result);
|
|
}
|
|
|
|
// An AddrMode is trivial if it involves no calculation i.e. it is just a base
|
|
// with no offset.
|
|
bool isTrivial() {
|
|
// An AddrMode is (BaseGV + BaseReg + BaseOffs + ScaleReg * Scale) so it is
|
|
// trivial if at most one of these terms is nonzero, except that BaseGV and
|
|
// BaseReg both being zero actually means a null pointer value, which we
|
|
// consider to be 'non-zero' here.
|
|
return !BaseOffs && !Scale && !(BaseGV && BaseReg);
|
|
}
|
|
|
|
Value *GetFieldAsValue(FieldName Field, Type *IntPtrTy) {
|
|
switch (Field) {
|
|
default:
|
|
return nullptr;
|
|
case BaseRegField:
|
|
return BaseReg;
|
|
case BaseGVField:
|
|
return BaseGV;
|
|
case ScaledRegField:
|
|
return ScaledReg;
|
|
case BaseOffsField:
|
|
return ConstantInt::get(IntPtrTy, BaseOffs);
|
|
}
|
|
}
|
|
|
|
void SetCombinedField(FieldName Field, Value *V,
|
|
const SmallVectorImpl<ExtAddrMode> &AddrModes) {
|
|
switch (Field) {
|
|
default:
|
|
llvm_unreachable("Unhandled fields are expected to be rejected earlier");
|
|
break;
|
|
case ExtAddrMode::BaseRegField:
|
|
BaseReg = V;
|
|
break;
|
|
case ExtAddrMode::BaseGVField:
|
|
// A combined BaseGV is an Instruction, not a GlobalValue, so it goes
|
|
// in the BaseReg field.
|
|
assert(BaseReg == nullptr);
|
|
BaseReg = V;
|
|
BaseGV = nullptr;
|
|
break;
|
|
case ExtAddrMode::ScaledRegField:
|
|
ScaledReg = V;
|
|
// If we have a mix of scaled and unscaled addrmodes then we want scale
|
|
// to be the scale and not zero.
|
|
if (!Scale)
|
|
for (const ExtAddrMode &AM : AddrModes)
|
|
if (AM.Scale) {
|
|
Scale = AM.Scale;
|
|
break;
|
|
}
|
|
break;
|
|
case ExtAddrMode::BaseOffsField:
|
|
// The offset is no longer a constant, so it goes in ScaledReg with a
|
|
// scale of 1.
|
|
assert(ScaledReg == nullptr);
|
|
ScaledReg = V;
|
|
Scale = 1;
|
|
BaseOffs = 0;
|
|
break;
|
|
}
|
|
}
|
|
};
|
|
|
|
} // end anonymous namespace
|
|
|
|
#ifndef NDEBUG
|
|
static inline raw_ostream &operator<<(raw_ostream &OS, const ExtAddrMode &AM) {
|
|
AM.print(OS);
|
|
return OS;
|
|
}
|
|
#endif
|
|
|
|
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
|
|
void ExtAddrMode::print(raw_ostream &OS) const {
|
|
bool NeedPlus = false;
|
|
OS << "[";
|
|
if (BaseGV) {
|
|
OS << (NeedPlus ? " + " : "")
|
|
<< "GV:";
|
|
BaseGV->printAsOperand(OS, /*PrintType=*/false);
|
|
NeedPlus = true;
|
|
}
|
|
|
|
if (BaseOffs) {
|
|
OS << (NeedPlus ? " + " : "")
|
|
<< BaseOffs;
|
|
NeedPlus = true;
|
|
}
|
|
|
|
if (BaseReg) {
|
|
OS << (NeedPlus ? " + " : "")
|
|
<< "Base:";
|
|
BaseReg->printAsOperand(OS, /*PrintType=*/false);
|
|
NeedPlus = true;
|
|
}
|
|
if (Scale) {
|
|
OS << (NeedPlus ? " + " : "")
|
|
<< Scale << "*";
|
|
ScaledReg->printAsOperand(OS, /*PrintType=*/false);
|
|
}
|
|
|
|
OS << ']';
|
|
}
|
|
|
|
LLVM_DUMP_METHOD void ExtAddrMode::dump() const {
|
|
print(dbgs());
|
|
dbgs() << '\n';
|
|
}
|
|
#endif
|
|
|
|
namespace {
|
|
|
|
/// This class provides transaction based operation on the IR.
|
|
/// Every change made through this class is recorded in the internal state and
|
|
/// can be undone (rollback) until commit is called.
|
|
class TypePromotionTransaction {
|
|
/// This represents the common interface of the individual transaction.
|
|
/// Each class implements the logic for doing one specific modification on
|
|
/// the IR via the TypePromotionTransaction.
|
|
class TypePromotionAction {
|
|
protected:
|
|
/// The Instruction modified.
|
|
Instruction *Inst;
|
|
|
|
public:
|
|
/// Constructor of the action.
|
|
/// The constructor performs the related action on the IR.
|
|
TypePromotionAction(Instruction *Inst) : Inst(Inst) {}
|
|
|
|
virtual ~TypePromotionAction() = default;
|
|
|
|
/// Undo the modification done by this action.
|
|
/// When this method is called, the IR must be in the same state as it was
|
|
/// before this action was applied.
|
|
/// \pre Undoing the action works if and only if the IR is in the exact same
|
|
/// state as it was directly after this action was applied.
|
|
virtual void undo() = 0;
|
|
|
|
/// Advocate every change made by this action.
|
|
/// When the results on the IR of the action are to be kept, it is important
|
|
/// to call this function, otherwise hidden information may be kept forever.
|
|
virtual void commit() {
|
|
// Nothing to be done, this action is not doing anything.
|
|
}
|
|
};
|
|
|
|
/// Utility to remember the position of an instruction.
|
|
class InsertionHandler {
|
|
/// Position of an instruction.
|
|
/// Either an instruction:
|
|
/// - Is the first in a basic block: BB is used.
|
|
/// - Has a previous instruction: PrevInst is used.
|
|
union {
|
|
Instruction *PrevInst;
|
|
BasicBlock *BB;
|
|
} Point;
|
|
|
|
/// Remember whether or not the instruction had a previous instruction.
|
|
bool HasPrevInstruction;
|
|
|
|
public:
|
|
/// Record the position of \p Inst.
|
|
InsertionHandler(Instruction *Inst) {
|
|
BasicBlock::iterator It = Inst->getIterator();
|
|
HasPrevInstruction = (It != (Inst->getParent()->begin()));
|
|
if (HasPrevInstruction)
|
|
Point.PrevInst = &*--It;
|
|
else
|
|
Point.BB = Inst->getParent();
|
|
}
|
|
|
|
/// Insert \p Inst at the recorded position.
|
|
void insert(Instruction *Inst) {
|
|
if (HasPrevInstruction) {
|
|
if (Inst->getParent())
|
|
Inst->removeFromParent();
|
|
Inst->insertAfter(Point.PrevInst);
|
|
} else {
|
|
Instruction *Position = &*Point.BB->getFirstInsertionPt();
|
|
if (Inst->getParent())
|
|
Inst->moveBefore(Position);
|
|
else
|
|
Inst->insertBefore(Position);
|
|
}
|
|
}
|
|
};
|
|
|
|
/// Move an instruction before another.
|
|
class InstructionMoveBefore : public TypePromotionAction {
|
|
/// Original position of the instruction.
|
|
InsertionHandler Position;
|
|
|
|
public:
|
|
/// Move \p Inst before \p Before.
|
|
InstructionMoveBefore(Instruction *Inst, Instruction *Before)
|
|
: TypePromotionAction(Inst), Position(Inst) {
|
|
LLVM_DEBUG(dbgs() << "Do: move: " << *Inst << "\nbefore: " << *Before
|
|
<< "\n");
|
|
Inst->moveBefore(Before);
|
|
}
|
|
|
|
/// Move the instruction back to its original position.
|
|
void undo() override {
|
|
LLVM_DEBUG(dbgs() << "Undo: moveBefore: " << *Inst << "\n");
|
|
Position.insert(Inst);
|
|
}
|
|
};
|
|
|
|
/// Set the operand of an instruction with a new value.
|
|
class OperandSetter : public TypePromotionAction {
|
|
/// Original operand of the instruction.
|
|
Value *Origin;
|
|
|
|
/// Index of the modified instruction.
|
|
unsigned Idx;
|
|
|
|
public:
|
|
/// Set \p Idx operand of \p Inst with \p NewVal.
|
|
OperandSetter(Instruction *Inst, unsigned Idx, Value *NewVal)
|
|
: TypePromotionAction(Inst), Idx(Idx) {
|
|
LLVM_DEBUG(dbgs() << "Do: setOperand: " << Idx << "\n"
|
|
<< "for:" << *Inst << "\n"
|
|
<< "with:" << *NewVal << "\n");
|
|
Origin = Inst->getOperand(Idx);
|
|
Inst->setOperand(Idx, NewVal);
|
|
}
|
|
|
|
/// Restore the original value of the instruction.
|
|
void undo() override {
|
|
LLVM_DEBUG(dbgs() << "Undo: setOperand:" << Idx << "\n"
|
|
<< "for: " << *Inst << "\n"
|
|
<< "with: " << *Origin << "\n");
|
|
Inst->setOperand(Idx, Origin);
|
|
}
|
|
};
|
|
|
|
/// Hide the operands of an instruction.
|
|
/// Do as if this instruction was not using any of its operands.
|
|
class OperandsHider : public TypePromotionAction {
|
|
/// The list of original operands.
|
|
SmallVector<Value *, 4> OriginalValues;
|
|
|
|
public:
|
|
/// Remove \p Inst from the uses of the operands of \p Inst.
|
|
OperandsHider(Instruction *Inst) : TypePromotionAction(Inst) {
|
|
LLVM_DEBUG(dbgs() << "Do: OperandsHider: " << *Inst << "\n");
|
|
unsigned NumOpnds = Inst->getNumOperands();
|
|
OriginalValues.reserve(NumOpnds);
|
|
for (unsigned It = 0; It < NumOpnds; ++It) {
|
|
// Save the current operand.
|
|
Value *Val = Inst->getOperand(It);
|
|
OriginalValues.push_back(Val);
|
|
// Set a dummy one.
|
|
// We could use OperandSetter here, but that would imply an overhead
|
|
// that we are not willing to pay.
|
|
Inst->setOperand(It, UndefValue::get(Val->getType()));
|
|
}
|
|
}
|
|
|
|
/// Restore the original list of uses.
|
|
void undo() override {
|
|
LLVM_DEBUG(dbgs() << "Undo: OperandsHider: " << *Inst << "\n");
|
|
for (unsigned It = 0, EndIt = OriginalValues.size(); It != EndIt; ++It)
|
|
Inst->setOperand(It, OriginalValues[It]);
|
|
}
|
|
};
|
|
|
|
/// Build a truncate instruction.
|
|
class TruncBuilder : public TypePromotionAction {
|
|
Value *Val;
|
|
|
|
public:
|
|
/// Build a truncate instruction of \p Opnd producing a \p Ty
|
|
/// result.
|
|
/// trunc Opnd to Ty.
|
|
TruncBuilder(Instruction *Opnd, Type *Ty) : TypePromotionAction(Opnd) {
|
|
IRBuilder<> Builder(Opnd);
|
|
Val = Builder.CreateTrunc(Opnd, Ty, "promoted");
|
|
LLVM_DEBUG(dbgs() << "Do: TruncBuilder: " << *Val << "\n");
|
|
}
|
|
|
|
/// Get the built value.
|
|
Value *getBuiltValue() { return Val; }
|
|
|
|
/// Remove the built instruction.
|
|
void undo() override {
|
|
LLVM_DEBUG(dbgs() << "Undo: TruncBuilder: " << *Val << "\n");
|
|
if (Instruction *IVal = dyn_cast<Instruction>(Val))
|
|
IVal->eraseFromParent();
|
|
}
|
|
};
|
|
|
|
/// Build a sign extension instruction.
|
|
class SExtBuilder : public TypePromotionAction {
|
|
Value *Val;
|
|
|
|
public:
|
|
/// Build a sign extension instruction of \p Opnd producing a \p Ty
|
|
/// result.
|
|
/// sext Opnd to Ty.
|
|
SExtBuilder(Instruction *InsertPt, Value *Opnd, Type *Ty)
|
|
: TypePromotionAction(InsertPt) {
|
|
IRBuilder<> Builder(InsertPt);
|
|
Val = Builder.CreateSExt(Opnd, Ty, "promoted");
|
|
LLVM_DEBUG(dbgs() << "Do: SExtBuilder: " << *Val << "\n");
|
|
}
|
|
|
|
/// Get the built value.
|
|
Value *getBuiltValue() { return Val; }
|
|
|
|
/// Remove the built instruction.
|
|
void undo() override {
|
|
LLVM_DEBUG(dbgs() << "Undo: SExtBuilder: " << *Val << "\n");
|
|
if (Instruction *IVal = dyn_cast<Instruction>(Val))
|
|
IVal->eraseFromParent();
|
|
}
|
|
};
|
|
|
|
/// Build a zero extension instruction.
|
|
class ZExtBuilder : public TypePromotionAction {
|
|
Value *Val;
|
|
|
|
public:
|
|
/// Build a zero extension instruction of \p Opnd producing a \p Ty
|
|
/// result.
|
|
/// zext Opnd to Ty.
|
|
ZExtBuilder(Instruction *InsertPt, Value *Opnd, Type *Ty)
|
|
: TypePromotionAction(InsertPt) {
|
|
IRBuilder<> Builder(InsertPt);
|
|
Val = Builder.CreateZExt(Opnd, Ty, "promoted");
|
|
LLVM_DEBUG(dbgs() << "Do: ZExtBuilder: " << *Val << "\n");
|
|
}
|
|
|
|
/// Get the built value.
|
|
Value *getBuiltValue() { return Val; }
|
|
|
|
/// Remove the built instruction.
|
|
void undo() override {
|
|
LLVM_DEBUG(dbgs() << "Undo: ZExtBuilder: " << *Val << "\n");
|
|
if (Instruction *IVal = dyn_cast<Instruction>(Val))
|
|
IVal->eraseFromParent();
|
|
}
|
|
};
|
|
|
|
/// Mutate an instruction to another type.
|
|
class TypeMutator : public TypePromotionAction {
|
|
/// Record the original type.
|
|
Type *OrigTy;
|
|
|
|
public:
|
|
/// Mutate the type of \p Inst into \p NewTy.
|
|
TypeMutator(Instruction *Inst, Type *NewTy)
|
|
: TypePromotionAction(Inst), OrigTy(Inst->getType()) {
|
|
LLVM_DEBUG(dbgs() << "Do: MutateType: " << *Inst << " with " << *NewTy
|
|
<< "\n");
|
|
Inst->mutateType(NewTy);
|
|
}
|
|
|
|
/// Mutate the instruction back to its original type.
|
|
void undo() override {
|
|
LLVM_DEBUG(dbgs() << "Undo: MutateType: " << *Inst << " with " << *OrigTy
|
|
<< "\n");
|
|
Inst->mutateType(OrigTy);
|
|
}
|
|
};
|
|
|
|
/// Replace the uses of an instruction by another instruction.
|
|
class UsesReplacer : public TypePromotionAction {
|
|
/// Helper structure to keep track of the replaced uses.
|
|
struct InstructionAndIdx {
|
|
/// The instruction using the instruction.
|
|
Instruction *Inst;
|
|
|
|
/// The index where this instruction is used for Inst.
|
|
unsigned Idx;
|
|
|
|
InstructionAndIdx(Instruction *Inst, unsigned Idx)
|
|
: Inst(Inst), Idx(Idx) {}
|
|
};
|
|
|
|
/// Keep track of the original uses (pair Instruction, Index).
|
|
SmallVector<InstructionAndIdx, 4> OriginalUses;
|
|
|
|
using use_iterator = SmallVectorImpl<InstructionAndIdx>::iterator;
|
|
|
|
public:
|
|
/// Replace all the use of \p Inst by \p New.
|
|
UsesReplacer(Instruction *Inst, Value *New) : TypePromotionAction(Inst) {
|
|
LLVM_DEBUG(dbgs() << "Do: UsersReplacer: " << *Inst << " with " << *New
|
|
<< "\n");
|
|
// Record the original uses.
|
|
for (Use &U : Inst->uses()) {
|
|
Instruction *UserI = cast<Instruction>(U.getUser());
|
|
OriginalUses.push_back(InstructionAndIdx(UserI, U.getOperandNo()));
|
|
}
|
|
// Now, we can replace the uses.
|
|
Inst->replaceAllUsesWith(New);
|
|
}
|
|
|
|
/// Reassign the original uses of Inst to Inst.
|
|
void undo() override {
|
|
LLVM_DEBUG(dbgs() << "Undo: UsersReplacer: " << *Inst << "\n");
|
|
for (use_iterator UseIt = OriginalUses.begin(),
|
|
EndIt = OriginalUses.end();
|
|
UseIt != EndIt; ++UseIt) {
|
|
UseIt->Inst->setOperand(UseIt->Idx, Inst);
|
|
}
|
|
}
|
|
};
|
|
|
|
/// Remove an instruction from the IR.
|
|
class InstructionRemover : public TypePromotionAction {
|
|
/// Original position of the instruction.
|
|
InsertionHandler Inserter;
|
|
|
|
/// Helper structure to hide all the link to the instruction. In other
|
|
/// words, this helps to do as if the instruction was removed.
|
|
OperandsHider Hider;
|
|
|
|
/// Keep track of the uses replaced, if any.
|
|
UsesReplacer *Replacer = nullptr;
|
|
|
|
/// Keep track of instructions removed.
|
|
SetOfInstrs &RemovedInsts;
|
|
|
|
public:
|
|
/// Remove all reference of \p Inst and optionally replace all its
|
|
/// uses with New.
|
|
/// \p RemovedInsts Keep track of the instructions removed by this Action.
|
|
/// \pre If !Inst->use_empty(), then New != nullptr
|
|
InstructionRemover(Instruction *Inst, SetOfInstrs &RemovedInsts,
|
|
Value *New = nullptr)
|
|
: TypePromotionAction(Inst), Inserter(Inst), Hider(Inst),
|
|
RemovedInsts(RemovedInsts) {
|
|
if (New)
|
|
Replacer = new UsesReplacer(Inst, New);
|
|
LLVM_DEBUG(dbgs() << "Do: InstructionRemover: " << *Inst << "\n");
|
|
RemovedInsts.insert(Inst);
|
|
/// The instructions removed here will be freed after completing
|
|
/// optimizeBlock() for all blocks as we need to keep track of the
|
|
/// removed instructions during promotion.
|
|
Inst->removeFromParent();
|
|
}
|
|
|
|
~InstructionRemover() override { delete Replacer; }
|
|
|
|
/// Resurrect the instruction and reassign it to the proper uses if
|
|
/// new value was provided when build this action.
|
|
void undo() override {
|
|
LLVM_DEBUG(dbgs() << "Undo: InstructionRemover: " << *Inst << "\n");
|
|
Inserter.insert(Inst);
|
|
if (Replacer)
|
|
Replacer->undo();
|
|
Hider.undo();
|
|
RemovedInsts.erase(Inst);
|
|
}
|
|
};
|
|
|
|
public:
|
|
/// Restoration point.
|
|
/// The restoration point is a pointer to an action instead of an iterator
|
|
/// because the iterator may be invalidated but not the pointer.
|
|
using ConstRestorationPt = const TypePromotionAction *;
|
|
|
|
TypePromotionTransaction(SetOfInstrs &RemovedInsts)
|
|
: RemovedInsts(RemovedInsts) {}
|
|
|
|
/// Advocate every changes made in that transaction.
|
|
void commit();
|
|
|
|
/// Undo all the changes made after the given point.
|
|
void rollback(ConstRestorationPt Point);
|
|
|
|
/// Get the current restoration point.
|
|
ConstRestorationPt getRestorationPoint() const;
|
|
|
|
/// \name API for IR modification with state keeping to support rollback.
|
|
/// @{
|
|
/// Same as Instruction::setOperand.
|
|
void setOperand(Instruction *Inst, unsigned Idx, Value *NewVal);
|
|
|
|
/// Same as Instruction::eraseFromParent.
|
|
void eraseInstruction(Instruction *Inst, Value *NewVal = nullptr);
|
|
|
|
/// Same as Value::replaceAllUsesWith.
|
|
void replaceAllUsesWith(Instruction *Inst, Value *New);
|
|
|
|
/// Same as Value::mutateType.
|
|
void mutateType(Instruction *Inst, Type *NewTy);
|
|
|
|
/// Same as IRBuilder::createTrunc.
|
|
Value *createTrunc(Instruction *Opnd, Type *Ty);
|
|
|
|
/// Same as IRBuilder::createSExt.
|
|
Value *createSExt(Instruction *Inst, Value *Opnd, Type *Ty);
|
|
|
|
/// Same as IRBuilder::createZExt.
|
|
Value *createZExt(Instruction *Inst, Value *Opnd, Type *Ty);
|
|
|
|
/// Same as Instruction::moveBefore.
|
|
void moveBefore(Instruction *Inst, Instruction *Before);
|
|
/// @}
|
|
|
|
private:
|
|
/// The ordered list of actions made so far.
|
|
SmallVector<std::unique_ptr<TypePromotionAction>, 16> Actions;
|
|
|
|
using CommitPt = SmallVectorImpl<std::unique_ptr<TypePromotionAction>>::iterator;
|
|
|
|
SetOfInstrs &RemovedInsts;
|
|
};
|
|
|
|
} // end anonymous namespace
|
|
|
|
void TypePromotionTransaction::setOperand(Instruction *Inst, unsigned Idx,
|
|
Value *NewVal) {
|
|
Actions.push_back(llvm::make_unique<TypePromotionTransaction::OperandSetter>(
|
|
Inst, Idx, NewVal));
|
|
}
|
|
|
|
void TypePromotionTransaction::eraseInstruction(Instruction *Inst,
|
|
Value *NewVal) {
|
|
Actions.push_back(
|
|
llvm::make_unique<TypePromotionTransaction::InstructionRemover>(
|
|
Inst, RemovedInsts, NewVal));
|
|
}
|
|
|
|
void TypePromotionTransaction::replaceAllUsesWith(Instruction *Inst,
|
|
Value *New) {
|
|
Actions.push_back(
|
|
llvm::make_unique<TypePromotionTransaction::UsesReplacer>(Inst, New));
|
|
}
|
|
|
|
void TypePromotionTransaction::mutateType(Instruction *Inst, Type *NewTy) {
|
|
Actions.push_back(
|
|
llvm::make_unique<TypePromotionTransaction::TypeMutator>(Inst, NewTy));
|
|
}
|
|
|
|
Value *TypePromotionTransaction::createTrunc(Instruction *Opnd,
|
|
Type *Ty) {
|
|
std::unique_ptr<TruncBuilder> Ptr(new TruncBuilder(Opnd, Ty));
|
|
Value *Val = Ptr->getBuiltValue();
|
|
Actions.push_back(std::move(Ptr));
|
|
return Val;
|
|
}
|
|
|
|
Value *TypePromotionTransaction::createSExt(Instruction *Inst,
|
|
Value *Opnd, Type *Ty) {
|
|
std::unique_ptr<SExtBuilder> Ptr(new SExtBuilder(Inst, Opnd, Ty));
|
|
Value *Val = Ptr->getBuiltValue();
|
|
Actions.push_back(std::move(Ptr));
|
|
return Val;
|
|
}
|
|
|
|
Value *TypePromotionTransaction::createZExt(Instruction *Inst,
|
|
Value *Opnd, Type *Ty) {
|
|
std::unique_ptr<ZExtBuilder> Ptr(new ZExtBuilder(Inst, Opnd, Ty));
|
|
Value *Val = Ptr->getBuiltValue();
|
|
Actions.push_back(std::move(Ptr));
|
|
return Val;
|
|
}
|
|
|
|
void TypePromotionTransaction::moveBefore(Instruction *Inst,
|
|
Instruction *Before) {
|
|
Actions.push_back(
|
|
llvm::make_unique<TypePromotionTransaction::InstructionMoveBefore>(
|
|
Inst, Before));
|
|
}
|
|
|
|
TypePromotionTransaction::ConstRestorationPt
|
|
TypePromotionTransaction::getRestorationPoint() const {
|
|
return !Actions.empty() ? Actions.back().get() : nullptr;
|
|
}
|
|
|
|
void TypePromotionTransaction::commit() {
|
|
for (CommitPt It = Actions.begin(), EndIt = Actions.end(); It != EndIt;
|
|
++It)
|
|
(*It)->commit();
|
|
Actions.clear();
|
|
}
|
|
|
|
void TypePromotionTransaction::rollback(
|
|
TypePromotionTransaction::ConstRestorationPt Point) {
|
|
while (!Actions.empty() && Point != Actions.back().get()) {
|
|
std::unique_ptr<TypePromotionAction> Curr = Actions.pop_back_val();
|
|
Curr->undo();
|
|
}
|
|
}
|
|
|
|
namespace {
|
|
|
|
/// A helper class for matching addressing modes.
|
|
///
|
|
/// This encapsulates the logic for matching the target-legal addressing modes.
|
|
class AddressingModeMatcher {
|
|
SmallVectorImpl<Instruction*> &AddrModeInsts;
|
|
const TargetLowering &TLI;
|
|
const TargetRegisterInfo &TRI;
|
|
const DataLayout &DL;
|
|
|
|
/// AccessTy/MemoryInst - This is the type for the access (e.g. double) and
|
|
/// the memory instruction that we're computing this address for.
|
|
Type *AccessTy;
|
|
unsigned AddrSpace;
|
|
Instruction *MemoryInst;
|
|
|
|
/// This is the addressing mode that we're building up. This is
|
|
/// part of the return value of this addressing mode matching stuff.
|
|
ExtAddrMode &AddrMode;
|
|
|
|
/// The instructions inserted by other CodeGenPrepare optimizations.
|
|
const SetOfInstrs &InsertedInsts;
|
|
|
|
/// A map from the instructions to their type before promotion.
|
|
InstrToOrigTy &PromotedInsts;
|
|
|
|
/// The ongoing transaction where every action should be registered.
|
|
TypePromotionTransaction &TPT;
|
|
|
|
// A GEP which has too large offset to be folded into the addressing mode.
|
|
std::pair<AssertingVH<GetElementPtrInst>, int64_t> &LargeOffsetGEP;
|
|
|
|
/// This is set to true when we should not do profitability checks.
|
|
/// When true, IsProfitableToFoldIntoAddressingMode always returns true.
|
|
bool IgnoreProfitability;
|
|
|
|
AddressingModeMatcher(
|
|
SmallVectorImpl<Instruction *> &AMI, const TargetLowering &TLI,
|
|
const TargetRegisterInfo &TRI, Type *AT, unsigned AS, Instruction *MI,
|
|
ExtAddrMode &AM, const SetOfInstrs &InsertedInsts,
|
|
InstrToOrigTy &PromotedInsts, TypePromotionTransaction &TPT,
|
|
std::pair<AssertingVH<GetElementPtrInst>, int64_t> &LargeOffsetGEP)
|
|
: AddrModeInsts(AMI), TLI(TLI), TRI(TRI),
|
|
DL(MI->getModule()->getDataLayout()), AccessTy(AT), AddrSpace(AS),
|
|
MemoryInst(MI), AddrMode(AM), InsertedInsts(InsertedInsts),
|
|
PromotedInsts(PromotedInsts), TPT(TPT), LargeOffsetGEP(LargeOffsetGEP) {
|
|
IgnoreProfitability = false;
|
|
}
|
|
|
|
public:
|
|
/// Find the maximal addressing mode that a load/store of V can fold,
|
|
/// give an access type of AccessTy. This returns a list of involved
|
|
/// instructions in AddrModeInsts.
|
|
/// \p InsertedInsts The instructions inserted by other CodeGenPrepare
|
|
/// optimizations.
|
|
/// \p PromotedInsts maps the instructions to their type before promotion.
|
|
/// \p The ongoing transaction where every action should be registered.
|
|
static ExtAddrMode
|
|
Match(Value *V, Type *AccessTy, unsigned AS, Instruction *MemoryInst,
|
|
SmallVectorImpl<Instruction *> &AddrModeInsts,
|
|
const TargetLowering &TLI, const TargetRegisterInfo &TRI,
|
|
const SetOfInstrs &InsertedInsts, InstrToOrigTy &PromotedInsts,
|
|
TypePromotionTransaction &TPT,
|
|
std::pair<AssertingVH<GetElementPtrInst>, int64_t> &LargeOffsetGEP) {
|
|
ExtAddrMode Result;
|
|
|
|
bool Success = AddressingModeMatcher(AddrModeInsts, TLI, TRI, AccessTy, AS,
|
|
MemoryInst, Result, InsertedInsts,
|
|
PromotedInsts, TPT, LargeOffsetGEP)
|
|
.matchAddr(V, 0);
|
|
(void)Success; assert(Success && "Couldn't select *anything*?");
|
|
return Result;
|
|
}
|
|
|
|
private:
|
|
bool matchScaledValue(Value *ScaleReg, int64_t Scale, unsigned Depth);
|
|
bool matchAddr(Value *Addr, unsigned Depth);
|
|
bool matchOperationAddr(User *AddrInst, unsigned Opcode, unsigned Depth,
|
|
bool *MovedAway = nullptr);
|
|
bool isProfitableToFoldIntoAddressingMode(Instruction *I,
|
|
ExtAddrMode &AMBefore,
|
|
ExtAddrMode &AMAfter);
|
|
bool valueAlreadyLiveAtInst(Value *Val, Value *KnownLive1, Value *KnownLive2);
|
|
bool isPromotionProfitable(unsigned NewCost, unsigned OldCost,
|
|
Value *PromotedOperand) const;
|
|
};
|
|
|
|
/// Keep track of simplification of Phi nodes.
|
|
/// Accept the set of all phi nodes and erase phi node from this set
|
|
/// if it is simplified.
|
|
class SimplificationTracker {
|
|
DenseMap<Value *, Value *> Storage;
|
|
const SimplifyQuery &SQ;
|
|
// Tracks newly created Phi nodes. We use a SetVector to get deterministic
|
|
// order when iterating over the set in MatchPhiSet.
|
|
SmallSetVector<PHINode *, 32> AllPhiNodes;
|
|
// Tracks newly created Select nodes.
|
|
SmallPtrSet<SelectInst *, 32> AllSelectNodes;
|
|
|
|
public:
|
|
SimplificationTracker(const SimplifyQuery &sq)
|
|
: SQ(sq) {}
|
|
|
|
Value *Get(Value *V) {
|
|
do {
|
|
auto SV = Storage.find(V);
|
|
if (SV == Storage.end())
|
|
return V;
|
|
V = SV->second;
|
|
} while (true);
|
|
}
|
|
|
|
Value *Simplify(Value *Val) {
|
|
SmallVector<Value *, 32> WorkList;
|
|
SmallPtrSet<Value *, 32> Visited;
|
|
WorkList.push_back(Val);
|
|
while (!WorkList.empty()) {
|
|
auto P = WorkList.pop_back_val();
|
|
if (!Visited.insert(P).second)
|
|
continue;
|
|
if (auto *PI = dyn_cast<Instruction>(P))
|
|
if (Value *V = SimplifyInstruction(cast<Instruction>(PI), SQ)) {
|
|
for (auto *U : PI->users())
|
|
WorkList.push_back(cast<Value>(U));
|
|
Put(PI, V);
|
|
PI->replaceAllUsesWith(V);
|
|
if (auto *PHI = dyn_cast<PHINode>(PI))
|
|
AllPhiNodes.remove(PHI);
|
|
if (auto *Select = dyn_cast<SelectInst>(PI))
|
|
AllSelectNodes.erase(Select);
|
|
PI->eraseFromParent();
|
|
}
|
|
}
|
|
return Get(Val);
|
|
}
|
|
|
|
void Put(Value *From, Value *To) {
|
|
Storage.insert({ From, To });
|
|
}
|
|
|
|
void ReplacePhi(PHINode *From, PHINode *To) {
|
|
Value* OldReplacement = Get(From);
|
|
while (OldReplacement != From) {
|
|
From = To;
|
|
To = dyn_cast<PHINode>(OldReplacement);
|
|
OldReplacement = Get(From);
|
|
}
|
|
assert(Get(To) == To && "Replacement PHI node is already replaced.");
|
|
Put(From, To);
|
|
From->replaceAllUsesWith(To);
|
|
AllPhiNodes.remove(From);
|
|
From->eraseFromParent();
|
|
}
|
|
|
|
SmallSetVector<PHINode *, 32>& newPhiNodes() { return AllPhiNodes; }
|
|
|
|
void insertNewPhi(PHINode *PN) { AllPhiNodes.insert(PN); }
|
|
|
|
void insertNewSelect(SelectInst *SI) { AllSelectNodes.insert(SI); }
|
|
|
|
unsigned countNewPhiNodes() const { return AllPhiNodes.size(); }
|
|
|
|
unsigned countNewSelectNodes() const { return AllSelectNodes.size(); }
|
|
|
|
void destroyNewNodes(Type *CommonType) {
|
|
// For safe erasing, replace the uses with dummy value first.
|
|
auto Dummy = UndefValue::get(CommonType);
|
|
for (auto I : AllPhiNodes) {
|
|
I->replaceAllUsesWith(Dummy);
|
|
I->eraseFromParent();
|
|
}
|
|
AllPhiNodes.clear();
|
|
for (auto I : AllSelectNodes) {
|
|
I->replaceAllUsesWith(Dummy);
|
|
I->eraseFromParent();
|
|
}
|
|
AllSelectNodes.clear();
|
|
}
|
|
};
|
|
|
|
/// A helper class for combining addressing modes.
|
|
class AddressingModeCombiner {
|
|
typedef std::pair<Value *, BasicBlock *> ValueInBB;
|
|
typedef DenseMap<ValueInBB, Value *> FoldAddrToValueMapping;
|
|
typedef std::pair<PHINode *, PHINode *> PHIPair;
|
|
|
|
private:
|
|
/// The addressing modes we've collected.
|
|
SmallVector<ExtAddrMode, 16> AddrModes;
|
|
|
|
/// The field in which the AddrModes differ, when we have more than one.
|
|
ExtAddrMode::FieldName DifferentField = ExtAddrMode::NoField;
|
|
|
|
/// Are the AddrModes that we have all just equal to their original values?
|
|
bool AllAddrModesTrivial = true;
|
|
|
|
/// Common Type for all different fields in addressing modes.
|
|
Type *CommonType;
|
|
|
|
/// SimplifyQuery for simplifyInstruction utility.
|
|
const SimplifyQuery &SQ;
|
|
|
|
/// Original Address.
|
|
ValueInBB Original;
|
|
|
|
public:
|
|
AddressingModeCombiner(const SimplifyQuery &_SQ, ValueInBB OriginalValue)
|
|
: CommonType(nullptr), SQ(_SQ), Original(OriginalValue) {}
|
|
|
|
/// Get the combined AddrMode
|
|
const ExtAddrMode &getAddrMode() const {
|
|
return AddrModes[0];
|
|
}
|
|
|
|
/// Add a new AddrMode if it's compatible with the AddrModes we already
|
|
/// have.
|
|
/// \return True iff we succeeded in doing so.
|
|
bool addNewAddrMode(ExtAddrMode &NewAddrMode) {
|
|
// Take note of if we have any non-trivial AddrModes, as we need to detect
|
|
// when all AddrModes are trivial as then we would introduce a phi or select
|
|
// which just duplicates what's already there.
|
|
AllAddrModesTrivial = AllAddrModesTrivial && NewAddrMode.isTrivial();
|
|
|
|
// If this is the first addrmode then everything is fine.
|
|
if (AddrModes.empty()) {
|
|
AddrModes.emplace_back(NewAddrMode);
|
|
return true;
|
|
}
|
|
|
|
// Figure out how different this is from the other address modes, which we
|
|
// can do just by comparing against the first one given that we only care
|
|
// about the cumulative difference.
|
|
ExtAddrMode::FieldName ThisDifferentField =
|
|
AddrModes[0].compare(NewAddrMode);
|
|
if (DifferentField == ExtAddrMode::NoField)
|
|
DifferentField = ThisDifferentField;
|
|
else if (DifferentField != ThisDifferentField)
|
|
DifferentField = ExtAddrMode::MultipleFields;
|
|
|
|
// If NewAddrMode differs in more than one dimension we cannot handle it.
|
|
bool CanHandle = DifferentField != ExtAddrMode::MultipleFields;
|
|
|
|
// If Scale Field is different then we reject.
|
|
CanHandle = CanHandle && DifferentField != ExtAddrMode::ScaleField;
|
|
|
|
// We also must reject the case when base offset is different and
|
|
// scale reg is not null, we cannot handle this case due to merge of
|
|
// different offsets will be used as ScaleReg.
|
|
CanHandle = CanHandle && (DifferentField != ExtAddrMode::BaseOffsField ||
|
|
!NewAddrMode.ScaledReg);
|
|
|
|
// We also must reject the case when GV is different and BaseReg installed
|
|
// due to we want to use base reg as a merge of GV values.
|
|
CanHandle = CanHandle && (DifferentField != ExtAddrMode::BaseGVField ||
|
|
!NewAddrMode.HasBaseReg);
|
|
|
|
// Even if NewAddMode is the same we still need to collect it due to
|
|
// original value is different. And later we will need all original values
|
|
// as anchors during finding the common Phi node.
|
|
if (CanHandle)
|
|
AddrModes.emplace_back(NewAddrMode);
|
|
else
|
|
AddrModes.clear();
|
|
|
|
return CanHandle;
|
|
}
|
|
|
|
/// Combine the addressing modes we've collected into a single
|
|
/// addressing mode.
|
|
/// \return True iff we successfully combined them or we only had one so
|
|
/// didn't need to combine them anyway.
|
|
bool combineAddrModes() {
|
|
// If we have no AddrModes then they can't be combined.
|
|
if (AddrModes.size() == 0)
|
|
return false;
|
|
|
|
// A single AddrMode can trivially be combined.
|
|
if (AddrModes.size() == 1 || DifferentField == ExtAddrMode::NoField)
|
|
return true;
|
|
|
|
// If the AddrModes we collected are all just equal to the value they are
|
|
// derived from then combining them wouldn't do anything useful.
|
|
if (AllAddrModesTrivial)
|
|
return false;
|
|
|
|
if (!addrModeCombiningAllowed())
|
|
return false;
|
|
|
|
// Build a map between <original value, basic block where we saw it> to
|
|
// value of base register.
|
|
// Bail out if there is no common type.
|
|
FoldAddrToValueMapping Map;
|
|
if (!initializeMap(Map))
|
|
return false;
|
|
|
|
Value *CommonValue = findCommon(Map);
|
|
if (CommonValue)
|
|
AddrModes[0].SetCombinedField(DifferentField, CommonValue, AddrModes);
|
|
return CommonValue != nullptr;
|
|
}
|
|
|
|
private:
|
|
/// Initialize Map with anchor values. For address seen in some BB
|
|
/// we set the value of different field saw in this address.
|
|
/// If address is not an instruction than basic block is set to null.
|
|
/// At the same time we find a common type for different field we will
|
|
/// use to create new Phi/Select nodes. Keep it in CommonType field.
|
|
/// Return false if there is no common type found.
|
|
bool initializeMap(FoldAddrToValueMapping &Map) {
|
|
// Keep track of keys where the value is null. We will need to replace it
|
|
// with constant null when we know the common type.
|
|
SmallVector<ValueInBB, 2> NullValue;
|
|
Type *IntPtrTy = SQ.DL.getIntPtrType(AddrModes[0].OriginalValue->getType());
|
|
for (auto &AM : AddrModes) {
|
|
BasicBlock *BB = nullptr;
|
|
if (Instruction *I = dyn_cast<Instruction>(AM.OriginalValue))
|
|
BB = I->getParent();
|
|
|
|
Value *DV = AM.GetFieldAsValue(DifferentField, IntPtrTy);
|
|
if (DV) {
|
|
auto *Type = DV->getType();
|
|
if (CommonType && CommonType != Type)
|
|
return false;
|
|
CommonType = Type;
|
|
Map[{ AM.OriginalValue, BB }] = DV;
|
|
} else {
|
|
NullValue.push_back({ AM.OriginalValue, BB });
|
|
}
|
|
}
|
|
assert(CommonType && "At least one non-null value must be!");
|
|
for (auto VIBB : NullValue)
|
|
Map[VIBB] = Constant::getNullValue(CommonType);
|
|
return true;
|
|
}
|
|
|
|
/// We have mapping between value A and basic block where value A
|
|
/// seen to other value B where B was a field in addressing mode represented
|
|
/// by A. Also we have an original value C representing an address in some
|
|
/// basic block. Traversing from C through phi and selects we ended up with
|
|
/// A's in a map. This utility function tries to find a value V which is a
|
|
/// field in addressing mode C and traversing through phi nodes and selects
|
|
/// we will end up in corresponded values B in a map.
|
|
/// The utility will create a new Phi/Selects if needed.
|
|
// The simple example looks as follows:
|
|
// BB1:
|
|
// p1 = b1 + 40
|
|
// br cond BB2, BB3
|
|
// BB2:
|
|
// p2 = b2 + 40
|
|
// br BB3
|
|
// BB3:
|
|
// p = phi [p1, BB1], [p2, BB2]
|
|
// v = load p
|
|
// Map is
|
|
// <p1, BB1> -> b1
|
|
// <p2, BB2> -> b2
|
|
// Request is
|
|
// <p, BB3> -> ?
|
|
// The function tries to find or build phi [b1, BB1], [b2, BB2] in BB3
|
|
Value *findCommon(FoldAddrToValueMapping &Map) {
|
|
// Tracks the simplification of newly created phi nodes. The reason we use
|
|
// this mapping is because we will add new created Phi nodes in AddrToBase.
|
|
// Simplification of Phi nodes is recursive, so some Phi node may
|
|
// be simplified after we added it to AddrToBase.
|
|
// Using this mapping we can find the current value in AddrToBase.
|
|
SimplificationTracker ST(SQ);
|
|
|
|
// First step, DFS to create PHI nodes for all intermediate blocks.
|
|
// Also fill traverse order for the second step.
|
|
SmallVector<ValueInBB, 32> TraverseOrder;
|
|
InsertPlaceholders(Map, TraverseOrder, ST);
|
|
|
|
// Second Step, fill new nodes by merged values and simplify if possible.
|
|
FillPlaceholders(Map, TraverseOrder, ST);
|
|
|
|
if (!AddrSinkNewSelects && ST.countNewSelectNodes() > 0) {
|
|
ST.destroyNewNodes(CommonType);
|
|
return nullptr;
|
|
}
|
|
|
|
// Now we'd like to match New Phi nodes to existed ones.
|
|
unsigned PhiNotMatchedCount = 0;
|
|
if (!MatchPhiSet(ST, AddrSinkNewPhis, PhiNotMatchedCount)) {
|
|
ST.destroyNewNodes(CommonType);
|
|
return nullptr;
|
|
}
|
|
|
|
auto *Result = ST.Get(Map.find(Original)->second);
|
|
if (Result) {
|
|
NumMemoryInstsPhiCreated += ST.countNewPhiNodes() + PhiNotMatchedCount;
|
|
NumMemoryInstsSelectCreated += ST.countNewSelectNodes();
|
|
}
|
|
return Result;
|
|
}
|
|
|
|
/// Try to match PHI node to Candidate.
|
|
/// Matcher tracks the matched Phi nodes.
|
|
bool MatchPhiNode(PHINode *PHI, PHINode *Candidate,
|
|
SmallSetVector<PHIPair, 8> &Matcher,
|
|
SmallSetVector<PHINode *, 32> &PhiNodesToMatch) {
|
|
SmallVector<PHIPair, 8> WorkList;
|
|
Matcher.insert({ PHI, Candidate });
|
|
WorkList.push_back({ PHI, Candidate });
|
|
SmallSet<PHIPair, 8> Visited;
|
|
while (!WorkList.empty()) {
|
|
auto Item = WorkList.pop_back_val();
|
|
if (!Visited.insert(Item).second)
|
|
continue;
|
|
// We iterate over all incoming values to Phi to compare them.
|
|
// If values are different and both of them Phi and the first one is a
|
|
// Phi we added (subject to match) and both of them is in the same basic
|
|
// block then we can match our pair if values match. So we state that
|
|
// these values match and add it to work list to verify that.
|
|
for (auto B : Item.first->blocks()) {
|
|
Value *FirstValue = Item.first->getIncomingValueForBlock(B);
|
|
Value *SecondValue = Item.second->getIncomingValueForBlock(B);
|
|
if (FirstValue == SecondValue)
|
|
continue;
|
|
|
|
PHINode *FirstPhi = dyn_cast<PHINode>(FirstValue);
|
|
PHINode *SecondPhi = dyn_cast<PHINode>(SecondValue);
|
|
|
|
// One of them is not Phi or
|
|
// The first one is not Phi node from the set we'd like to match or
|
|
// Phi nodes from different basic blocks then
|
|
// we will not be able to match.
|
|
if (!FirstPhi || !SecondPhi || !PhiNodesToMatch.count(FirstPhi) ||
|
|
FirstPhi->getParent() != SecondPhi->getParent())
|
|
return false;
|
|
|
|
// If we already matched them then continue.
|
|
if (Matcher.count({ FirstPhi, SecondPhi }))
|
|
continue;
|
|
// So the values are different and does not match. So we need them to
|
|
// match.
|
|
Matcher.insert({ FirstPhi, SecondPhi });
|
|
// But me must check it.
|
|
WorkList.push_back({ FirstPhi, SecondPhi });
|
|
}
|
|
}
|
|
return true;
|
|
}
|
|
|
|
/// For the given set of PHI nodes (in the SimplificationTracker) try
|
|
/// to find their equivalents.
|
|
/// Returns false if this matching fails and creation of new Phi is disabled.
|
|
bool MatchPhiSet(SimplificationTracker &ST, bool AllowNewPhiNodes,
|
|
unsigned &PhiNotMatchedCount) {
|
|
// Use a SetVector for Matched to make sure we do replacements (ReplacePhi)
|
|
// in a deterministic order below.
|
|
SmallSetVector<PHIPair, 8> Matched;
|
|
SmallPtrSet<PHINode *, 8> WillNotMatch;
|
|
SmallSetVector<PHINode *, 32> &PhiNodesToMatch = ST.newPhiNodes();
|
|
while (PhiNodesToMatch.size()) {
|
|
PHINode *PHI = *PhiNodesToMatch.begin();
|
|
|
|
// Add us, if no Phi nodes in the basic block we do not match.
|
|
WillNotMatch.clear();
|
|
WillNotMatch.insert(PHI);
|
|
|
|
// Traverse all Phis until we found equivalent or fail to do that.
|
|
bool IsMatched = false;
|
|
for (auto &P : PHI->getParent()->phis()) {
|
|
if (&P == PHI)
|
|
continue;
|
|
if ((IsMatched = MatchPhiNode(PHI, &P, Matched, PhiNodesToMatch)))
|
|
break;
|
|
// If it does not match, collect all Phi nodes from matcher.
|
|
// if we end up with no match, them all these Phi nodes will not match
|
|
// later.
|
|
for (auto M : Matched)
|
|
WillNotMatch.insert(M.first);
|
|
Matched.clear();
|
|
}
|
|
if (IsMatched) {
|
|
// Replace all matched values and erase them.
|
|
for (auto MV : Matched)
|
|
ST.ReplacePhi(MV.first, MV.second);
|
|
Matched.clear();
|
|
continue;
|
|
}
|
|
// If we are not allowed to create new nodes then bail out.
|
|
if (!AllowNewPhiNodes)
|
|
return false;
|
|
// Just remove all seen values in matcher. They will not match anything.
|
|
PhiNotMatchedCount += WillNotMatch.size();
|
|
for (auto *P : WillNotMatch)
|
|
PhiNodesToMatch.remove(P);
|
|
}
|
|
return true;
|
|
}
|
|
/// Fill the placeholder with values from predecessors and simplify it.
|
|
void FillPlaceholders(FoldAddrToValueMapping &Map,
|
|
SmallVectorImpl<ValueInBB> &TraverseOrder,
|
|
SimplificationTracker &ST) {
|
|
while (!TraverseOrder.empty()) {
|
|
auto Current = TraverseOrder.pop_back_val();
|
|
assert(Map.find(Current) != Map.end() && "No node to fill!!!");
|
|
Value *CurrentValue = Current.first;
|
|
BasicBlock *CurrentBlock = Current.second;
|
|
Value *V = Map[Current];
|
|
|
|
if (SelectInst *Select = dyn_cast<SelectInst>(V)) {
|
|
// CurrentValue also must be Select.
|
|
auto *CurrentSelect = cast<SelectInst>(CurrentValue);
|
|
auto *TrueValue = CurrentSelect->getTrueValue();
|
|
ValueInBB TrueItem = { TrueValue, isa<Instruction>(TrueValue)
|
|
? CurrentBlock
|
|
: nullptr };
|
|
assert(Map.find(TrueItem) != Map.end() && "No True Value!");
|
|
Select->setTrueValue(ST.Get(Map[TrueItem]));
|
|
auto *FalseValue = CurrentSelect->getFalseValue();
|
|
ValueInBB FalseItem = { FalseValue, isa<Instruction>(FalseValue)
|
|
? CurrentBlock
|
|
: nullptr };
|
|
assert(Map.find(FalseItem) != Map.end() && "No False Value!");
|
|
Select->setFalseValue(ST.Get(Map[FalseItem]));
|
|
} else {
|
|
// Must be a Phi node then.
|
|
PHINode *PHI = cast<PHINode>(V);
|
|
// Fill the Phi node with values from predecessors.
|
|
bool IsDefinedInThisBB =
|
|
cast<Instruction>(CurrentValue)->getParent() == CurrentBlock;
|
|
auto *CurrentPhi = dyn_cast<PHINode>(CurrentValue);
|
|
for (auto B : predecessors(CurrentBlock)) {
|
|
Value *PV = IsDefinedInThisBB
|
|
? CurrentPhi->getIncomingValueForBlock(B)
|
|
: CurrentValue;
|
|
ValueInBB item = { PV, isa<Instruction>(PV) ? B : nullptr };
|
|
assert(Map.find(item) != Map.end() && "No predecessor Value!");
|
|
PHI->addIncoming(ST.Get(Map[item]), B);
|
|
}
|
|
}
|
|
// Simplify if possible.
|
|
Map[Current] = ST.Simplify(V);
|
|
}
|
|
}
|
|
|
|
/// Starting from value recursively iterates over predecessors up to known
|
|
/// ending values represented in a map. For each traversed block inserts
|
|
/// a placeholder Phi or Select.
|
|
/// Reports all new created Phi/Select nodes by adding them to set.
|
|
/// Also reports and order in what basic blocks have been traversed.
|
|
void InsertPlaceholders(FoldAddrToValueMapping &Map,
|
|
SmallVectorImpl<ValueInBB> &TraverseOrder,
|
|
SimplificationTracker &ST) {
|
|
SmallVector<ValueInBB, 32> Worklist;
|
|
assert((isa<PHINode>(Original.first) || isa<SelectInst>(Original.first)) &&
|
|
"Address must be a Phi or Select node");
|
|
auto *Dummy = UndefValue::get(CommonType);
|
|
Worklist.push_back(Original);
|
|
while (!Worklist.empty()) {
|
|
auto Current = Worklist.pop_back_val();
|
|
// If value is not an instruction it is something global, constant,
|
|
// parameter and we can say that this value is observable in any block.
|
|
// Set block to null to denote it.
|
|
// Also please take into account that it is how we build anchors.
|
|
if (!isa<Instruction>(Current.first))
|
|
Current.second = nullptr;
|
|
// if it is already visited or it is an ending value then skip it.
|
|
if (Map.find(Current) != Map.end())
|
|
continue;
|
|
TraverseOrder.push_back(Current);
|
|
|
|
Value *CurrentValue = Current.first;
|
|
BasicBlock *CurrentBlock = Current.second;
|
|
// CurrentValue must be a Phi node or select. All others must be covered
|
|
// by anchors.
|
|
Instruction *CurrentI = cast<Instruction>(CurrentValue);
|
|
bool IsDefinedInThisBB = CurrentI->getParent() == CurrentBlock;
|
|
|
|
unsigned PredCount = pred_size(CurrentBlock);
|
|
// if Current Value is not defined in this basic block we are interested
|
|
// in values in predecessors.
|
|
if (!IsDefinedInThisBB) {
|
|
assert(PredCount && "Unreachable block?!");
|
|
PHINode *PHI = PHINode::Create(CommonType, PredCount, "sunk_phi",
|
|
&CurrentBlock->front());
|
|
Map[Current] = PHI;
|
|
ST.insertNewPhi(PHI);
|
|
// Add all predecessors in work list.
|
|
for (auto B : predecessors(CurrentBlock))
|
|
Worklist.push_back({ CurrentValue, B });
|
|
continue;
|
|
}
|
|
// Value is defined in this basic block.
|
|
if (SelectInst *OrigSelect = dyn_cast<SelectInst>(CurrentI)) {
|
|
// Is it OK to get metadata from OrigSelect?!
|
|
// Create a Select placeholder with dummy value.
|
|
SelectInst *Select =
|
|
SelectInst::Create(OrigSelect->getCondition(), Dummy, Dummy,
|
|
OrigSelect->getName(), OrigSelect, OrigSelect);
|
|
Map[Current] = Select;
|
|
ST.insertNewSelect(Select);
|
|
// We are interested in True and False value in this basic block.
|
|
Worklist.push_back({ OrigSelect->getTrueValue(), CurrentBlock });
|
|
Worklist.push_back({ OrigSelect->getFalseValue(), CurrentBlock });
|
|
} else {
|
|
// It must be a Phi node then.
|
|
auto *CurrentPhi = cast<PHINode>(CurrentI);
|
|
// Create new Phi node for merge of bases.
|
|
assert(PredCount && "Unreachable block?!");
|
|
PHINode *PHI = PHINode::Create(CommonType, PredCount, "sunk_phi",
|
|
&CurrentBlock->front());
|
|
Map[Current] = PHI;
|
|
ST.insertNewPhi(PHI);
|
|
|
|
// Add all predecessors in work list.
|
|
for (auto B : predecessors(CurrentBlock))
|
|
Worklist.push_back({ CurrentPhi->getIncomingValueForBlock(B), B });
|
|
}
|
|
}
|
|
}
|
|
|
|
bool addrModeCombiningAllowed() {
|
|
if (DisableComplexAddrModes)
|
|
return false;
|
|
switch (DifferentField) {
|
|
default:
|
|
return false;
|
|
case ExtAddrMode::BaseRegField:
|
|
return AddrSinkCombineBaseReg;
|
|
case ExtAddrMode::BaseGVField:
|
|
return AddrSinkCombineBaseGV;
|
|
case ExtAddrMode::BaseOffsField:
|
|
return AddrSinkCombineBaseOffs;
|
|
case ExtAddrMode::ScaledRegField:
|
|
return AddrSinkCombineScaledReg;
|
|
}
|
|
}
|
|
};
|
|
} // end anonymous namespace
|
|
|
|
/// Try adding ScaleReg*Scale to the current addressing mode.
|
|
/// Return true and update AddrMode if this addr mode is legal for the target,
|
|
/// false if not.
|
|
bool AddressingModeMatcher::matchScaledValue(Value *ScaleReg, int64_t Scale,
|
|
unsigned Depth) {
|
|
// If Scale is 1, then this is the same as adding ScaleReg to the addressing
|
|
// mode. Just process that directly.
|
|
if (Scale == 1)
|
|
return matchAddr(ScaleReg, Depth);
|
|
|
|
// If the scale is 0, it takes nothing to add this.
|
|
if (Scale == 0)
|
|
return true;
|
|
|
|
// If we already have a scale of this value, we can add to it, otherwise, we
|
|
// need an available scale field.
|
|
if (AddrMode.Scale != 0 && AddrMode.ScaledReg != ScaleReg)
|
|
return false;
|
|
|
|
ExtAddrMode TestAddrMode = AddrMode;
|
|
|
|
// Add scale to turn X*4+X*3 -> X*7. This could also do things like
|
|
// [A+B + A*7] -> [B+A*8].
|
|
TestAddrMode.Scale += Scale;
|
|
TestAddrMode.ScaledReg = ScaleReg;
|
|
|
|
// If the new address isn't legal, bail out.
|
|
if (!TLI.isLegalAddressingMode(DL, TestAddrMode, AccessTy, AddrSpace))
|
|
return false;
|
|
|
|
// It was legal, so commit it.
|
|
AddrMode = TestAddrMode;
|
|
|
|
// Okay, we decided that we can add ScaleReg+Scale to AddrMode. Check now
|
|
// to see if ScaleReg is actually X+C. If so, we can turn this into adding
|
|
// X*Scale + C*Scale to addr mode.
|
|
ConstantInt *CI = nullptr; Value *AddLHS = nullptr;
|
|
if (isa<Instruction>(ScaleReg) && // not a constant expr.
|
|
match(ScaleReg, m_Add(m_Value(AddLHS), m_ConstantInt(CI)))) {
|
|
TestAddrMode.ScaledReg = AddLHS;
|
|
TestAddrMode.BaseOffs += CI->getSExtValue()*TestAddrMode.Scale;
|
|
|
|
// If this addressing mode is legal, commit it and remember that we folded
|
|
// this instruction.
|
|
if (TLI.isLegalAddressingMode(DL, TestAddrMode, AccessTy, AddrSpace)) {
|
|
AddrModeInsts.push_back(cast<Instruction>(ScaleReg));
|
|
AddrMode = TestAddrMode;
|
|
return true;
|
|
}
|
|
}
|
|
|
|
// Otherwise, not (x+c)*scale, just return what we have.
|
|
return true;
|
|
}
|
|
|
|
/// This is a little filter, which returns true if an addressing computation
|
|
/// involving I might be folded into a load/store accessing it.
|
|
/// This doesn't need to be perfect, but needs to accept at least
|
|
/// the set of instructions that MatchOperationAddr can.
|
|
static bool MightBeFoldableInst(Instruction *I) {
|
|
switch (I->getOpcode()) {
|
|
case Instruction::BitCast:
|
|
case Instruction::AddrSpaceCast:
|
|
// Don't touch identity bitcasts.
|
|
if (I->getType() == I->getOperand(0)->getType())
|
|
return false;
|
|
return I->getType()->isIntOrPtrTy();
|
|
case Instruction::PtrToInt:
|
|
// PtrToInt is always a noop, as we know that the int type is pointer sized.
|
|
return true;
|
|
case Instruction::IntToPtr:
|
|
// We know the input is intptr_t, so this is foldable.
|
|
return true;
|
|
case Instruction::Add:
|
|
return true;
|
|
case Instruction::Mul:
|
|
case Instruction::Shl:
|
|
// Can only handle X*C and X << C.
|
|
return isa<ConstantInt>(I->getOperand(1));
|
|
case Instruction::GetElementPtr:
|
|
return true;
|
|
default:
|
|
return false;
|
|
}
|
|
}
|
|
|
|
/// Check whether or not \p Val is a legal instruction for \p TLI.
|
|
/// \note \p Val is assumed to be the product of some type promotion.
|
|
/// Therefore if \p Val has an undefined state in \p TLI, this is assumed
|
|
/// to be legal, as the non-promoted value would have had the same state.
|
|
static bool isPromotedInstructionLegal(const TargetLowering &TLI,
|
|
const DataLayout &DL, Value *Val) {
|
|
Instruction *PromotedInst = dyn_cast<Instruction>(Val);
|
|
if (!PromotedInst)
|
|
return false;
|
|
int ISDOpcode = TLI.InstructionOpcodeToISD(PromotedInst->getOpcode());
|
|
// If the ISDOpcode is undefined, it was undefined before the promotion.
|
|
if (!ISDOpcode)
|
|
return true;
|
|
// Otherwise, check if the promoted instruction is legal or not.
|
|
return TLI.isOperationLegalOrCustom(
|
|
ISDOpcode, TLI.getValueType(DL, PromotedInst->getType()));
|
|
}
|
|
|
|
namespace {
|
|
|
|
/// Hepler class to perform type promotion.
|
|
class TypePromotionHelper {
|
|
/// Utility function to add a promoted instruction \p ExtOpnd to
|
|
/// \p PromotedInsts and record the type of extension we have seen.
|
|
static void addPromotedInst(InstrToOrigTy &PromotedInsts,
|
|
Instruction *ExtOpnd,
|
|
bool IsSExt) {
|
|
ExtType ExtTy = IsSExt ? SignExtension : ZeroExtension;
|
|
InstrToOrigTy::iterator It = PromotedInsts.find(ExtOpnd);
|
|
if (It != PromotedInsts.end()) {
|
|
// If the new extension is same as original, the information in
|
|
// PromotedInsts[ExtOpnd] is still correct.
|
|
if (It->second.getInt() == ExtTy)
|
|
return;
|
|
|
|
// Now the new extension is different from old extension, we make
|
|
// the type information invalid by setting extension type to
|
|
// BothExtension.
|
|
ExtTy = BothExtension;
|
|
}
|
|
PromotedInsts[ExtOpnd] = TypeIsSExt(ExtOpnd->getType(), ExtTy);
|
|
}
|
|
|
|
/// Utility function to query the original type of instruction \p Opnd
|
|
/// with a matched extension type. If the extension doesn't match, we
|
|
/// cannot use the information we had on the original type.
|
|
/// BothExtension doesn't match any extension type.
|
|
static const Type *getOrigType(const InstrToOrigTy &PromotedInsts,
|
|
Instruction *Opnd,
|
|
bool IsSExt) {
|
|
ExtType ExtTy = IsSExt ? SignExtension : ZeroExtension;
|
|
InstrToOrigTy::const_iterator It = PromotedInsts.find(Opnd);
|
|
if (It != PromotedInsts.end() && It->second.getInt() == ExtTy)
|
|
return It->second.getPointer();
|
|
return nullptr;
|
|
}
|
|
|
|
/// Utility function to check whether or not a sign or zero extension
|
|
/// of \p Inst with \p ConsideredExtType can be moved through \p Inst by
|
|
/// either using the operands of \p Inst or promoting \p Inst.
|
|
/// The type of the extension is defined by \p IsSExt.
|
|
/// In other words, check if:
|
|
/// ext (Ty Inst opnd1 opnd2 ... opndN) to ConsideredExtType.
|
|
/// #1 Promotion applies:
|
|
/// ConsideredExtType Inst (ext opnd1 to ConsideredExtType, ...).
|
|
/// #2 Operand reuses:
|
|
/// ext opnd1 to ConsideredExtType.
|
|
/// \p PromotedInsts maps the instructions to their type before promotion.
|
|
static bool canGetThrough(const Instruction *Inst, Type *ConsideredExtType,
|
|
const InstrToOrigTy &PromotedInsts, bool IsSExt);
|
|
|
|
/// Utility function to determine if \p OpIdx should be promoted when
|
|
/// promoting \p Inst.
|
|
static bool shouldExtOperand(const Instruction *Inst, int OpIdx) {
|
|
return !(isa<SelectInst>(Inst) && OpIdx == 0);
|
|
}
|
|
|
|
/// Utility function to promote the operand of \p Ext when this
|
|
/// operand is a promotable trunc or sext or zext.
|
|
/// \p PromotedInsts maps the instructions to their type before promotion.
|
|
/// \p CreatedInstsCost[out] contains the cost of all instructions
|
|
/// created to promote the operand of Ext.
|
|
/// Newly added extensions are inserted in \p Exts.
|
|
/// Newly added truncates are inserted in \p Truncs.
|
|
/// Should never be called directly.
|
|
/// \return The promoted value which is used instead of Ext.
|
|
static Value *promoteOperandForTruncAndAnyExt(
|
|
Instruction *Ext, TypePromotionTransaction &TPT,
|
|
InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
|
|
SmallVectorImpl<Instruction *> *Exts,
|
|
SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI);
|
|
|
|
/// Utility function to promote the operand of \p Ext when this
|
|
/// operand is promotable and is not a supported trunc or sext.
|
|
/// \p PromotedInsts maps the instructions to their type before promotion.
|
|
/// \p CreatedInstsCost[out] contains the cost of all the instructions
|
|
/// created to promote the operand of Ext.
|
|
/// Newly added extensions are inserted in \p Exts.
|
|
/// Newly added truncates are inserted in \p Truncs.
|
|
/// Should never be called directly.
|
|
/// \return The promoted value which is used instead of Ext.
|
|
static Value *promoteOperandForOther(Instruction *Ext,
|
|
TypePromotionTransaction &TPT,
|
|
InstrToOrigTy &PromotedInsts,
|
|
unsigned &CreatedInstsCost,
|
|
SmallVectorImpl<Instruction *> *Exts,
|
|
SmallVectorImpl<Instruction *> *Truncs,
|
|
const TargetLowering &TLI, bool IsSExt);
|
|
|
|
/// \see promoteOperandForOther.
|
|
static Value *signExtendOperandForOther(
|
|
Instruction *Ext, TypePromotionTransaction &TPT,
|
|
InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
|
|
SmallVectorImpl<Instruction *> *Exts,
|
|
SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI) {
|
|
return promoteOperandForOther(Ext, TPT, PromotedInsts, CreatedInstsCost,
|
|
Exts, Truncs, TLI, true);
|
|
}
|
|
|
|
/// \see promoteOperandForOther.
|
|
static Value *zeroExtendOperandForOther(
|
|
Instruction *Ext, TypePromotionTransaction &TPT,
|
|
InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
|
|
SmallVectorImpl<Instruction *> *Exts,
|
|
SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI) {
|
|
return promoteOperandForOther(Ext, TPT, PromotedInsts, CreatedInstsCost,
|
|
Exts, Truncs, TLI, false);
|
|
}
|
|
|
|
public:
|
|
/// Type for the utility function that promotes the operand of Ext.
|
|
using Action = Value *(*)(Instruction *Ext, TypePromotionTransaction &TPT,
|
|
InstrToOrigTy &PromotedInsts,
|
|
unsigned &CreatedInstsCost,
|
|
SmallVectorImpl<Instruction *> *Exts,
|
|
SmallVectorImpl<Instruction *> *Truncs,
|
|
const TargetLowering &TLI);
|
|
|
|
/// Given a sign/zero extend instruction \p Ext, return the appropriate
|
|
/// action to promote the operand of \p Ext instead of using Ext.
|
|
/// \return NULL if no promotable action is possible with the current
|
|
/// sign extension.
|
|
/// \p InsertedInsts keeps track of all the instructions inserted by the
|
|
/// other CodeGenPrepare optimizations. This information is important
|
|
/// because we do not want to promote these instructions as CodeGenPrepare
|
|
/// will reinsert them later. Thus creating an infinite loop: create/remove.
|
|
/// \p PromotedInsts maps the instructions to their type before promotion.
|
|
static Action getAction(Instruction *Ext, const SetOfInstrs &InsertedInsts,
|
|
const TargetLowering &TLI,
|
|
const InstrToOrigTy &PromotedInsts);
|
|
};
|
|
|
|
} // end anonymous namespace
|
|
|
|
bool TypePromotionHelper::canGetThrough(const Instruction *Inst,
|
|
Type *ConsideredExtType,
|
|
const InstrToOrigTy &PromotedInsts,
|
|
bool IsSExt) {
|
|
// The promotion helper does not know how to deal with vector types yet.
|
|
// To be able to fix that, we would need to fix the places where we
|
|
// statically extend, e.g., constants and such.
|
|
if (Inst->getType()->isVectorTy())
|
|
return false;
|
|
|
|
// We can always get through zext.
|
|
if (isa<ZExtInst>(Inst))
|
|
return true;
|
|
|
|
// sext(sext) is ok too.
|
|
if (IsSExt && isa<SExtInst>(Inst))
|
|
return true;
|
|
|
|
// We can get through binary operator, if it is legal. In other words, the
|
|
// binary operator must have a nuw or nsw flag.
|
|
const BinaryOperator *BinOp = dyn_cast<BinaryOperator>(Inst);
|
|
if (BinOp && isa<OverflowingBinaryOperator>(BinOp) &&
|
|
((!IsSExt && BinOp->hasNoUnsignedWrap()) ||
|
|
(IsSExt && BinOp->hasNoSignedWrap())))
|
|
return true;
|
|
|
|
// ext(and(opnd, cst)) --> and(ext(opnd), ext(cst))
|
|
if ((Inst->getOpcode() == Instruction::And ||
|
|
Inst->getOpcode() == Instruction::Or))
|
|
return true;
|
|
|
|
// ext(xor(opnd, cst)) --> xor(ext(opnd), ext(cst))
|
|
if (Inst->getOpcode() == Instruction::Xor) {
|
|
const ConstantInt *Cst = dyn_cast<ConstantInt>(Inst->getOperand(1));
|
|
// Make sure it is not a NOT.
|
|
if (Cst && !Cst->getValue().isAllOnesValue())
|
|
return true;
|
|
}
|
|
|
|
// zext(shrl(opnd, cst)) --> shrl(zext(opnd), zext(cst))
|
|
// It may change a poisoned value into a regular value, like
|
|
// zext i32 (shrl i8 %val, 12) --> shrl i32 (zext i8 %val), 12
|
|
// poisoned value regular value
|
|
// It should be OK since undef covers valid value.
|
|
if (Inst->getOpcode() == Instruction::LShr && !IsSExt)
|
|
return true;
|
|
|
|
// and(ext(shl(opnd, cst)), cst) --> and(shl(ext(opnd), ext(cst)), cst)
|
|
// It may change a poisoned value into a regular value, like
|
|
// zext i32 (shl i8 %val, 12) --> shl i32 (zext i8 %val), 12
|
|
// poisoned value regular value
|
|
// It should be OK since undef covers valid value.
|
|
if (Inst->getOpcode() == Instruction::Shl && Inst->hasOneUse()) {
|
|
const Instruction *ExtInst =
|
|
dyn_cast<const Instruction>(*Inst->user_begin());
|
|
if (ExtInst->hasOneUse()) {
|
|
const Instruction *AndInst =
|
|
dyn_cast<const Instruction>(*ExtInst->user_begin());
|
|
if (AndInst && AndInst->getOpcode() == Instruction::And) {
|
|
const ConstantInt *Cst = dyn_cast<ConstantInt>(AndInst->getOperand(1));
|
|
if (Cst &&
|
|
Cst->getValue().isIntN(Inst->getType()->getIntegerBitWidth()))
|
|
return true;
|
|
}
|
|
}
|
|
}
|
|
|
|
// Check if we can do the following simplification.
|
|
// ext(trunc(opnd)) --> ext(opnd)
|
|
if (!isa<TruncInst>(Inst))
|
|
return false;
|
|
|
|
Value *OpndVal = Inst->getOperand(0);
|
|
// Check if we can use this operand in the extension.
|
|
// If the type is larger than the result type of the extension, we cannot.
|
|
if (!OpndVal->getType()->isIntegerTy() ||
|
|
OpndVal->getType()->getIntegerBitWidth() >
|
|
ConsideredExtType->getIntegerBitWidth())
|
|
return false;
|
|
|
|
// If the operand of the truncate is not an instruction, we will not have
|
|
// any information on the dropped bits.
|
|
// (Actually we could for constant but it is not worth the extra logic).
|
|
Instruction *Opnd = dyn_cast<Instruction>(OpndVal);
|
|
if (!Opnd)
|
|
return false;
|
|
|
|
// Check if the source of the type is narrow enough.
|
|
// I.e., check that trunc just drops extended bits of the same kind of
|
|
// the extension.
|
|
// #1 get the type of the operand and check the kind of the extended bits.
|
|
const Type *OpndType = getOrigType(PromotedInsts, Opnd, IsSExt);
|
|
if (OpndType)
|
|
;
|
|
else if ((IsSExt && isa<SExtInst>(Opnd)) || (!IsSExt && isa<ZExtInst>(Opnd)))
|
|
OpndType = Opnd->getOperand(0)->getType();
|
|
else
|
|
return false;
|
|
|
|
// #2 check that the truncate just drops extended bits.
|
|
return Inst->getType()->getIntegerBitWidth() >=
|
|
OpndType->getIntegerBitWidth();
|
|
}
|
|
|
|
TypePromotionHelper::Action TypePromotionHelper::getAction(
|
|
Instruction *Ext, const SetOfInstrs &InsertedInsts,
|
|
const TargetLowering &TLI, const InstrToOrigTy &PromotedInsts) {
|
|
assert((isa<SExtInst>(Ext) || isa<ZExtInst>(Ext)) &&
|
|
"Unexpected instruction type");
|
|
Instruction *ExtOpnd = dyn_cast<Instruction>(Ext->getOperand(0));
|
|
Type *ExtTy = Ext->getType();
|
|
bool IsSExt = isa<SExtInst>(Ext);
|
|
// If the operand of the extension is not an instruction, we cannot
|
|
// get through.
|
|
// If it, check we can get through.
|
|
if (!ExtOpnd || !canGetThrough(ExtOpnd, ExtTy, PromotedInsts, IsSExt))
|
|
return nullptr;
|
|
|
|
// Do not promote if the operand has been added by codegenprepare.
|
|
// Otherwise, it means we are undoing an optimization that is likely to be
|
|
// redone, thus causing potential infinite loop.
|
|
if (isa<TruncInst>(ExtOpnd) && InsertedInsts.count(ExtOpnd))
|
|
return nullptr;
|
|
|
|
// SExt or Trunc instructions.
|
|
// Return the related handler.
|
|
if (isa<SExtInst>(ExtOpnd) || isa<TruncInst>(ExtOpnd) ||
|
|
isa<ZExtInst>(ExtOpnd))
|
|
return promoteOperandForTruncAndAnyExt;
|
|
|
|
// Regular instruction.
|
|
// Abort early if we will have to insert non-free instructions.
|
|
if (!ExtOpnd->hasOneUse() && !TLI.isTruncateFree(ExtTy, ExtOpnd->getType()))
|
|
return nullptr;
|
|
return IsSExt ? signExtendOperandForOther : zeroExtendOperandForOther;
|
|
}
|
|
|
|
Value *TypePromotionHelper::promoteOperandForTruncAndAnyExt(
|
|
Instruction *SExt, TypePromotionTransaction &TPT,
|
|
InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
|
|
SmallVectorImpl<Instruction *> *Exts,
|
|
SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI) {
|
|
// By construction, the operand of SExt is an instruction. Otherwise we cannot
|
|
// get through it and this method should not be called.
|
|
Instruction *SExtOpnd = cast<Instruction>(SExt->getOperand(0));
|
|
Value *ExtVal = SExt;
|
|
bool HasMergedNonFreeExt = false;
|
|
if (isa<ZExtInst>(SExtOpnd)) {
|
|
// Replace s|zext(zext(opnd))
|
|
// => zext(opnd).
|
|
HasMergedNonFreeExt = !TLI.isExtFree(SExtOpnd);
|
|
Value *ZExt =
|
|
TPT.createZExt(SExt, SExtOpnd->getOperand(0), SExt->getType());
|
|
TPT.replaceAllUsesWith(SExt, ZExt);
|
|
TPT.eraseInstruction(SExt);
|
|
ExtVal = ZExt;
|
|
} else {
|
|
// Replace z|sext(trunc(opnd)) or sext(sext(opnd))
|
|
// => z|sext(opnd).
|
|
TPT.setOperand(SExt, 0, SExtOpnd->getOperand(0));
|
|
}
|
|
CreatedInstsCost = 0;
|
|
|
|
// Remove dead code.
|
|
if (SExtOpnd->use_empty())
|
|
TPT.eraseInstruction(SExtOpnd);
|
|
|
|
// Check if the extension is still needed.
|
|
Instruction *ExtInst = dyn_cast<Instruction>(ExtVal);
|
|
if (!ExtInst || ExtInst->getType() != ExtInst->getOperand(0)->getType()) {
|
|
if (ExtInst) {
|
|
if (Exts)
|
|
Exts->push_back(ExtInst);
|
|
CreatedInstsCost = !TLI.isExtFree(ExtInst) && !HasMergedNonFreeExt;
|
|
}
|
|
return ExtVal;
|
|
}
|
|
|
|
// At this point we have: ext ty opnd to ty.
|
|
// Reassign the uses of ExtInst to the opnd and remove ExtInst.
|
|
Value *NextVal = ExtInst->getOperand(0);
|
|
TPT.eraseInstruction(ExtInst, NextVal);
|
|
return NextVal;
|
|
}
|
|
|
|
Value *TypePromotionHelper::promoteOperandForOther(
|
|
Instruction *Ext, TypePromotionTransaction &TPT,
|
|
InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,
|
|
SmallVectorImpl<Instruction *> *Exts,
|
|
SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI,
|
|
bool IsSExt) {
|
|
// By construction, the operand of Ext is an instruction. Otherwise we cannot
|
|
// get through it and this method should not be called.
|
|
Instruction *ExtOpnd = cast<Instruction>(Ext->getOperand(0));
|
|
CreatedInstsCost = 0;
|
|
if (!ExtOpnd->hasOneUse()) {
|
|
// ExtOpnd will be promoted.
|
|
// All its uses, but Ext, will need to use a truncated value of the
|
|
// promoted version.
|
|
// Create the truncate now.
|
|
Value *Trunc = TPT.createTrunc(Ext, ExtOpnd->getType());
|
|
if (Instruction *ITrunc = dyn_cast<Instruction>(Trunc)) {
|
|
// Insert it just after the definition.
|
|
ITrunc->moveAfter(ExtOpnd);
|
|
if (Truncs)
|
|
Truncs->push_back(ITrunc);
|
|
}
|
|
|
|
TPT.replaceAllUsesWith(ExtOpnd, Trunc);
|
|
// Restore the operand of Ext (which has been replaced by the previous call
|
|
// to replaceAllUsesWith) to avoid creating a cycle trunc <-> sext.
|
|
TPT.setOperand(Ext, 0, ExtOpnd);
|
|
}
|
|
|
|
// Get through the Instruction:
|
|
// 1. Update its type.
|
|
// 2. Replace the uses of Ext by Inst.
|
|
// 3. Extend each operand that needs to be extended.
|
|
|
|
// Remember the original type of the instruction before promotion.
|
|
// This is useful to know that the high bits are sign extended bits.
|
|
addPromotedInst(PromotedInsts, ExtOpnd, IsSExt);
|
|
// Step #1.
|
|
TPT.mutateType(ExtOpnd, Ext->getType());
|
|
// Step #2.
|
|
TPT.replaceAllUsesWith(Ext, ExtOpnd);
|
|
// Step #3.
|
|
Instruction *ExtForOpnd = Ext;
|
|
|
|
LLVM_DEBUG(dbgs() << "Propagate Ext to operands\n");
|
|
for (int OpIdx = 0, EndOpIdx = ExtOpnd->getNumOperands(); OpIdx != EndOpIdx;
|
|
++OpIdx) {
|
|
LLVM_DEBUG(dbgs() << "Operand:\n" << *(ExtOpnd->getOperand(OpIdx)) << '\n');
|
|
if (ExtOpnd->getOperand(OpIdx)->getType() == Ext->getType() ||
|
|
!shouldExtOperand(ExtOpnd, OpIdx)) {
|
|
LLVM_DEBUG(dbgs() << "No need to propagate\n");
|
|
continue;
|
|
}
|
|
// Check if we can statically extend the operand.
|
|
Value *Opnd = ExtOpnd->getOperand(OpIdx);
|
|
if (const ConstantInt *Cst = dyn_cast<ConstantInt>(Opnd)) {
|
|
LLVM_DEBUG(dbgs() << "Statically extend\n");
|
|
unsigned BitWidth = Ext->getType()->getIntegerBitWidth();
|
|
APInt CstVal = IsSExt ? Cst->getValue().sext(BitWidth)
|
|
: Cst->getValue().zext(BitWidth);
|
|
TPT.setOperand(ExtOpnd, OpIdx, ConstantInt::get(Ext->getType(), CstVal));
|
|
continue;
|
|
}
|
|
// UndefValue are typed, so we have to statically sign extend them.
|
|
if (isa<UndefValue>(Opnd)) {
|
|
LLVM_DEBUG(dbgs() << "Statically extend\n");
|
|
TPT.setOperand(ExtOpnd, OpIdx, UndefValue::get(Ext->getType()));
|
|
continue;
|
|
}
|
|
|
|
// Otherwise we have to explicitly sign extend the operand.
|
|
// Check if Ext was reused to extend an operand.
|
|
if (!ExtForOpnd) {
|
|
// If yes, create a new one.
|
|
LLVM_DEBUG(dbgs() << "More operands to ext\n");
|
|
Value *ValForExtOpnd = IsSExt ? TPT.createSExt(Ext, Opnd, Ext->getType())
|
|
: TPT.createZExt(Ext, Opnd, Ext->getType());
|
|
if (!isa<Instruction>(ValForExtOpnd)) {
|
|
TPT.setOperand(ExtOpnd, OpIdx, ValForExtOpnd);
|
|
continue;
|
|
}
|
|
ExtForOpnd = cast<Instruction>(ValForExtOpnd);
|
|
}
|
|
if (Exts)
|
|
Exts->push_back(ExtForOpnd);
|
|
TPT.setOperand(ExtForOpnd, 0, Opnd);
|
|
|
|
// Move the sign extension before the insertion point.
|
|
TPT.moveBefore(ExtForOpnd, ExtOpnd);
|
|
TPT.setOperand(ExtOpnd, OpIdx, ExtForOpnd);
|
|
CreatedInstsCost += !TLI.isExtFree(ExtForOpnd);
|
|
// If more sext are required, new instructions will have to be created.
|
|
ExtForOpnd = nullptr;
|
|
}
|
|
if (ExtForOpnd == Ext) {
|
|
LLVM_DEBUG(dbgs() << "Extension is useless now\n");
|
|
TPT.eraseInstruction(Ext);
|
|
}
|
|
return ExtOpnd;
|
|
}
|
|
|
|
/// Check whether or not promoting an instruction to a wider type is profitable.
|
|
/// \p NewCost gives the cost of extension instructions created by the
|
|
/// promotion.
|
|
/// \p OldCost gives the cost of extension instructions before the promotion
|
|
/// plus the number of instructions that have been
|
|
/// matched in the addressing mode the promotion.
|
|
/// \p PromotedOperand is the value that has been promoted.
|
|
/// \return True if the promotion is profitable, false otherwise.
|
|
bool AddressingModeMatcher::isPromotionProfitable(
|
|
unsigned NewCost, unsigned OldCost, Value *PromotedOperand) const {
|
|
LLVM_DEBUG(dbgs() << "OldCost: " << OldCost << "\tNewCost: " << NewCost
|
|
<< '\n');
|
|
// The cost of the new extensions is greater than the cost of the
|
|
// old extension plus what we folded.
|
|
// This is not profitable.
|
|
if (NewCost > OldCost)
|
|
return false;
|
|
if (NewCost < OldCost)
|
|
return true;
|
|
// The promotion is neutral but it may help folding the sign extension in
|
|
// loads for instance.
|
|
// Check that we did not create an illegal instruction.
|
|
return isPromotedInstructionLegal(TLI, DL, PromotedOperand);
|
|
}
|
|
|
|
/// Given an instruction or constant expr, see if we can fold the operation
|
|
/// into the addressing mode. If so, update the addressing mode and return
|
|
/// true, otherwise return false without modifying AddrMode.
|
|
/// If \p MovedAway is not NULL, it contains the information of whether or
|
|
/// not AddrInst has to be folded into the addressing mode on success.
|
|
/// If \p MovedAway == true, \p AddrInst will not be part of the addressing
|
|
/// because it has been moved away.
|
|
/// Thus AddrInst must not be added in the matched instructions.
|
|
/// This state can happen when AddrInst is a sext, since it may be moved away.
|
|
/// Therefore, AddrInst may not be valid when MovedAway is true and it must
|
|
/// not be referenced anymore.
|
|
bool AddressingModeMatcher::matchOperationAddr(User *AddrInst, unsigned Opcode,
|
|
unsigned Depth,
|
|
bool *MovedAway) {
|
|
// Avoid exponential behavior on extremely deep expression trees.
|
|
if (Depth >= 5) return false;
|
|
|
|
// By default, all matched instructions stay in place.
|
|
if (MovedAway)
|
|
*MovedAway = false;
|
|
|
|
switch (Opcode) {
|
|
case Instruction::PtrToInt:
|
|
// PtrToInt is always a noop, as we know that the int type is pointer sized.
|
|
return matchAddr(AddrInst->getOperand(0), Depth);
|
|
case Instruction::IntToPtr: {
|
|
auto AS = AddrInst->getType()->getPointerAddressSpace();
|
|
auto PtrTy = MVT::getIntegerVT(DL.getPointerSizeInBits(AS));
|
|
// This inttoptr is a no-op if the integer type is pointer sized.
|
|
if (TLI.getValueType(DL, AddrInst->getOperand(0)->getType()) == PtrTy)
|
|
return matchAddr(AddrInst->getOperand(0), Depth);
|
|
return false;
|
|
}
|
|
case Instruction::BitCast:
|
|
// BitCast is always a noop, and we can handle it as long as it is
|
|
// int->int or pointer->pointer (we don't want int<->fp or something).
|
|
if (AddrInst->getOperand(0)->getType()->isIntOrPtrTy() &&
|
|
// Don't touch identity bitcasts. These were probably put here by LSR,
|
|
// and we don't want to mess around with them. Assume it knows what it
|
|
// is doing.
|
|
AddrInst->getOperand(0)->getType() != AddrInst->getType())
|
|
return matchAddr(AddrInst->getOperand(0), Depth);
|
|
return false;
|
|
case Instruction::AddrSpaceCast: {
|
|
unsigned SrcAS
|
|
= AddrInst->getOperand(0)->getType()->getPointerAddressSpace();
|
|
unsigned DestAS = AddrInst->getType()->getPointerAddressSpace();
|
|
if (TLI.isNoopAddrSpaceCast(SrcAS, DestAS))
|
|
return matchAddr(AddrInst->getOperand(0), Depth);
|
|
return false;
|
|
}
|
|
case Instruction::Add: {
|
|
// Check to see if we can merge in the RHS then the LHS. If so, we win.
|
|
ExtAddrMode BackupAddrMode = AddrMode;
|
|
unsigned OldSize = AddrModeInsts.size();
|
|
// Start a transaction at this point.
|
|
// The LHS may match but not the RHS.
|
|
// Therefore, we need a higher level restoration point to undo partially
|
|
// matched operation.
|
|
TypePromotionTransaction::ConstRestorationPt LastKnownGood =
|
|
TPT.getRestorationPoint();
|
|
|
|
if (matchAddr(AddrInst->getOperand(1), Depth+1) &&
|
|
matchAddr(AddrInst->getOperand(0), Depth+1))
|
|
return true;
|
|
|
|
// Restore the old addr mode info.
|
|
AddrMode = BackupAddrMode;
|
|
AddrModeInsts.resize(OldSize);
|
|
TPT.rollback(LastKnownGood);
|
|
|
|
// Otherwise this was over-aggressive. Try merging in the LHS then the RHS.
|
|
if (matchAddr(AddrInst->getOperand(0), Depth+1) &&
|
|
matchAddr(AddrInst->getOperand(1), Depth+1))
|
|
return true;
|
|
|
|
// Otherwise we definitely can't merge the ADD in.
|
|
AddrMode = BackupAddrMode;
|
|
AddrModeInsts.resize(OldSize);
|
|
TPT.rollback(LastKnownGood);
|
|
break;
|
|
}
|
|
//case Instruction::Or:
|
|
// TODO: We can handle "Or Val, Imm" iff this OR is equivalent to an ADD.
|
|
//break;
|
|
case Instruction::Mul:
|
|
case Instruction::Shl: {
|
|
// Can only handle X*C and X << C.
|
|
ConstantInt *RHS = dyn_cast<ConstantInt>(AddrInst->getOperand(1));
|
|
if (!RHS || RHS->getBitWidth() > 64)
|
|
return false;
|
|
int64_t Scale = RHS->getSExtValue();
|
|
if (Opcode == Instruction::Shl)
|
|
Scale = 1LL << Scale;
|
|
|
|
return matchScaledValue(AddrInst->getOperand(0), Scale, Depth);
|
|
}
|
|
case Instruction::GetElementPtr: {
|
|
// Scan the GEP. We check it if it contains constant offsets and at most
|
|
// one variable offset.
|
|
int VariableOperand = -1;
|
|
unsigned VariableScale = 0;
|
|
|
|
int64_t ConstantOffset = 0;
|
|
gep_type_iterator GTI = gep_type_begin(AddrInst);
|
|
for (unsigned i = 1, e = AddrInst->getNumOperands(); i != e; ++i, ++GTI) {
|
|
if (StructType *STy = GTI.getStructTypeOrNull()) {
|
|
const StructLayout *SL = DL.getStructLayout(STy);
|
|
unsigned Idx =
|
|
cast<ConstantInt>(AddrInst->getOperand(i))->getZExtValue();
|
|
ConstantOffset += SL->getElementOffset(Idx);
|
|
} else {
|
|
uint64_t TypeSize = DL.getTypeAllocSize(GTI.getIndexedType());
|
|
if (ConstantInt *CI = dyn_cast<ConstantInt>(AddrInst->getOperand(i))) {
|
|
const APInt &CVal = CI->getValue();
|
|
if (CVal.getMinSignedBits() <= 64) {
|
|
ConstantOffset += CVal.getSExtValue() * TypeSize;
|
|
continue;
|
|
}
|
|
}
|
|
if (TypeSize) { // Scales of zero don't do anything.
|
|
// We only allow one variable index at the moment.
|
|
if (VariableOperand != -1)
|
|
return false;
|
|
|
|
// Remember the variable index.
|
|
VariableOperand = i;
|
|
VariableScale = TypeSize;
|
|
}
|
|
}
|
|
}
|
|
|
|
// A common case is for the GEP to only do a constant offset. In this case,
|
|
// just add it to the disp field and check validity.
|
|
if (VariableOperand == -1) {
|
|
AddrMode.BaseOffs += ConstantOffset;
|
|
if (ConstantOffset == 0 ||
|
|
TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace)) {
|
|
// Check to see if we can fold the base pointer in too.
|
|
if (matchAddr(AddrInst->getOperand(0), Depth+1))
|
|
return true;
|
|
} else if (EnableGEPOffsetSplit && isa<GetElementPtrInst>(AddrInst) &&
|
|
TLI.shouldConsiderGEPOffsetSplit() && Depth == 0 &&
|
|
ConstantOffset > 0) {
|
|
// Record GEPs with non-zero offsets as candidates for splitting in the
|
|
// event that the offset cannot fit into the r+i addressing mode.
|
|
// Simple and common case that only one GEP is used in calculating the
|
|
// address for the memory access.
|
|
Value *Base = AddrInst->getOperand(0);
|
|
auto *BaseI = dyn_cast<Instruction>(Base);
|
|
auto *GEP = cast<GetElementPtrInst>(AddrInst);
|
|
if (isa<Argument>(Base) || isa<GlobalValue>(Base) ||
|
|
(BaseI && !isa<CastInst>(BaseI) &&
|
|
!isa<GetElementPtrInst>(BaseI))) {
|
|
// If the base is an instruction, make sure the GEP is not in the same
|
|
// basic block as the base. If the base is an argument or global
|
|
// value, make sure the GEP is not in the entry block. Otherwise,
|
|
// instruction selection can undo the split. Also make sure the
|
|
// parent block allows inserting non-PHI instructions before the
|
|
// terminator.
|
|
BasicBlock *Parent =
|
|
BaseI ? BaseI->getParent() : &GEP->getFunction()->getEntryBlock();
|
|
if (GEP->getParent() != Parent && !Parent->getTerminator()->isEHPad())
|
|
LargeOffsetGEP = std::make_pair(GEP, ConstantOffset);
|
|
}
|
|
}
|
|
AddrMode.BaseOffs -= ConstantOffset;
|
|
return false;
|
|
}
|
|
|
|
// Save the valid addressing mode in case we can't match.
|
|
ExtAddrMode BackupAddrMode = AddrMode;
|
|
unsigned OldSize = AddrModeInsts.size();
|
|
|
|
// See if the scale and offset amount is valid for this target.
|
|
AddrMode.BaseOffs += ConstantOffset;
|
|
|
|
// Match the base operand of the GEP.
|
|
if (!matchAddr(AddrInst->getOperand(0), Depth+1)) {
|
|
// If it couldn't be matched, just stuff the value in a register.
|
|
if (AddrMode.HasBaseReg) {
|
|
AddrMode = BackupAddrMode;
|
|
AddrModeInsts.resize(OldSize);
|
|
return false;
|
|
}
|
|
AddrMode.HasBaseReg = true;
|
|
AddrMode.BaseReg = AddrInst->getOperand(0);
|
|
}
|
|
|
|
// Match the remaining variable portion of the GEP.
|
|
if (!matchScaledValue(AddrInst->getOperand(VariableOperand), VariableScale,
|
|
Depth)) {
|
|
// If it couldn't be matched, try stuffing the base into a register
|
|
// instead of matching it, and retrying the match of the scale.
|
|
AddrMode = BackupAddrMode;
|
|
AddrModeInsts.resize(OldSize);
|
|
if (AddrMode.HasBaseReg)
|
|
return false;
|
|
AddrMode.HasBaseReg = true;
|
|
AddrMode.BaseReg = AddrInst->getOperand(0);
|
|
AddrMode.BaseOffs += ConstantOffset;
|
|
if (!matchScaledValue(AddrInst->getOperand(VariableOperand),
|
|
VariableScale, Depth)) {
|
|
// If even that didn't work, bail.
|
|
AddrMode = BackupAddrMode;
|
|
AddrModeInsts.resize(OldSize);
|
|
return false;
|
|
}
|
|
}
|
|
|
|
return true;
|
|
}
|
|
case Instruction::SExt:
|
|
case Instruction::ZExt: {
|
|
Instruction *Ext = dyn_cast<Instruction>(AddrInst);
|
|
if (!Ext)
|
|
return false;
|
|
|
|
// Try to move this ext out of the way of the addressing mode.
|
|
// Ask for a method for doing so.
|
|
TypePromotionHelper::Action TPH =
|
|
TypePromotionHelper::getAction(Ext, InsertedInsts, TLI, PromotedInsts);
|
|
if (!TPH)
|
|
return false;
|
|
|
|
TypePromotionTransaction::ConstRestorationPt LastKnownGood =
|
|
TPT.getRestorationPoint();
|
|
unsigned CreatedInstsCost = 0;
|
|
unsigned ExtCost = !TLI.isExtFree(Ext);
|
|
Value *PromotedOperand =
|
|
TPH(Ext, TPT, PromotedInsts, CreatedInstsCost, nullptr, nullptr, TLI);
|
|
// SExt has been moved away.
|
|
// Thus either it will be rematched later in the recursive calls or it is
|
|
// gone. Anyway, we must not fold it into the addressing mode at this point.
|
|
// E.g.,
|
|
// op = add opnd, 1
|
|
// idx = ext op
|
|
// addr = gep base, idx
|
|
// is now:
|
|
// promotedOpnd = ext opnd <- no match here
|
|
// op = promoted_add promotedOpnd, 1 <- match (later in recursive calls)
|
|
// addr = gep base, op <- match
|
|
if (MovedAway)
|
|
*MovedAway = true;
|
|
|
|
assert(PromotedOperand &&
|
|
"TypePromotionHelper should have filtered out those cases");
|
|
|
|
ExtAddrMode BackupAddrMode = AddrMode;
|
|
unsigned OldSize = AddrModeInsts.size();
|
|
|
|
if (!matchAddr(PromotedOperand, Depth) ||
|
|
// The total of the new cost is equal to the cost of the created
|
|
// instructions.
|
|
// The total of the old cost is equal to the cost of the extension plus
|
|
// what we have saved in the addressing mode.
|
|
!isPromotionProfitable(CreatedInstsCost,
|
|
ExtCost + (AddrModeInsts.size() - OldSize),
|
|
PromotedOperand)) {
|
|
AddrMode = BackupAddrMode;
|
|
AddrModeInsts.resize(OldSize);
|
|
LLVM_DEBUG(dbgs() << "Sign extension does not pay off: rollback\n");
|
|
TPT.rollback(LastKnownGood);
|
|
return false;
|
|
}
|
|
return true;
|
|
}
|
|
}
|
|
return false;
|
|
}
|
|
|
|
/// If we can, try to add the value of 'Addr' into the current addressing mode.
|
|
/// If Addr can't be added to AddrMode this returns false and leaves AddrMode
|
|
/// unmodified. This assumes that Addr is either a pointer type or intptr_t
|
|
/// for the target.
|
|
///
|
|
bool AddressingModeMatcher::matchAddr(Value *Addr, unsigned Depth) {
|
|
// Start a transaction at this point that we will rollback if the matching
|
|
// fails.
|
|
TypePromotionTransaction::ConstRestorationPt LastKnownGood =
|
|
TPT.getRestorationPoint();
|
|
if (ConstantInt *CI = dyn_cast<ConstantInt>(Addr)) {
|
|
// Fold in immediates if legal for the target.
|
|
AddrMode.BaseOffs += CI->getSExtValue();
|
|
if (TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace))
|
|
return true;
|
|
AddrMode.BaseOffs -= CI->getSExtValue();
|
|
} else if (GlobalValue *GV = dyn_cast<GlobalValue>(Addr)) {
|
|
// If this is a global variable, try to fold it into the addressing mode.
|
|
if (!AddrMode.BaseGV) {
|
|
AddrMode.BaseGV = GV;
|
|
if (TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace))
|
|
return true;
|
|
AddrMode.BaseGV = nullptr;
|
|
}
|
|
} else if (Instruction *I = dyn_cast<Instruction>(Addr)) {
|
|
ExtAddrMode BackupAddrMode = AddrMode;
|
|
unsigned OldSize = AddrModeInsts.size();
|
|
|
|
// Check to see if it is possible to fold this operation.
|
|
bool MovedAway = false;
|
|
if (matchOperationAddr(I, I->getOpcode(), Depth, &MovedAway)) {
|
|
// This instruction may have been moved away. If so, there is nothing
|
|
// to check here.
|
|
if (MovedAway)
|
|
return true;
|
|
// Okay, it's possible to fold this. Check to see if it is actually
|
|
// *profitable* to do so. We use a simple cost model to avoid increasing
|
|
// register pressure too much.
|
|
if (I->hasOneUse() ||
|
|
isProfitableToFoldIntoAddressingMode(I, BackupAddrMode, AddrMode)) {
|
|
AddrModeInsts.push_back(I);
|
|
return true;
|
|
}
|
|
|
|
// It isn't profitable to do this, roll back.
|
|
//cerr << "NOT FOLDING: " << *I;
|
|
AddrMode = BackupAddrMode;
|
|
AddrModeInsts.resize(OldSize);
|
|
TPT.rollback(LastKnownGood);
|
|
}
|
|
} else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Addr)) {
|
|
if (matchOperationAddr(CE, CE->getOpcode(), Depth))
|
|
return true;
|
|
TPT.rollback(LastKnownGood);
|
|
} else if (isa<ConstantPointerNull>(Addr)) {
|
|
// Null pointer gets folded without affecting the addressing mode.
|
|
return true;
|
|
}
|
|
|
|
// Worse case, the target should support [reg] addressing modes. :)
|
|
if (!AddrMode.HasBaseReg) {
|
|
AddrMode.HasBaseReg = true;
|
|
AddrMode.BaseReg = Addr;
|
|
// Still check for legality in case the target supports [imm] but not [i+r].
|
|
if (TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace))
|
|
return true;
|
|
AddrMode.HasBaseReg = false;
|
|
AddrMode.BaseReg = nullptr;
|
|
}
|
|
|
|
// If the base register is already taken, see if we can do [r+r].
|
|
if (AddrMode.Scale == 0) {
|
|
AddrMode.Scale = 1;
|
|
AddrMode.ScaledReg = Addr;
|
|
if (TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace))
|
|
return true;
|
|
AddrMode.Scale = 0;
|
|
AddrMode.ScaledReg = nullptr;
|
|
}
|
|
// Couldn't match.
|
|
TPT.rollback(LastKnownGood);
|
|
return false;
|
|
}
|
|
|
|
/// Check to see if all uses of OpVal by the specified inline asm call are due
|
|
/// to memory operands. If so, return true, otherwise return false.
|
|
static bool IsOperandAMemoryOperand(CallInst *CI, InlineAsm *IA, Value *OpVal,
|
|
const TargetLowering &TLI,
|
|
const TargetRegisterInfo &TRI) {
|
|
const Function *F = CI->getFunction();
|
|
TargetLowering::AsmOperandInfoVector TargetConstraints =
|
|
TLI.ParseConstraints(F->getParent()->getDataLayout(), &TRI,
|
|
ImmutableCallSite(CI));
|
|
|
|
for (unsigned i = 0, e = TargetConstraints.size(); i != e; ++i) {
|
|
TargetLowering::AsmOperandInfo &OpInfo = TargetConstraints[i];
|
|
|
|
// Compute the constraint code and ConstraintType to use.
|
|
TLI.ComputeConstraintToUse(OpInfo, SDValue());
|
|
|
|
// If this asm operand is our Value*, and if it isn't an indirect memory
|
|
// operand, we can't fold it!
|
|
if (OpInfo.CallOperandVal == OpVal &&
|
|
(OpInfo.ConstraintType != TargetLowering::C_Memory ||
|
|
!OpInfo.isIndirect))
|
|
return false;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
// Max number of memory uses to look at before aborting the search to conserve
|
|
// compile time.
|
|
static constexpr int MaxMemoryUsesToScan = 20;
|
|
|
|
/// Recursively walk all the uses of I until we find a memory use.
|
|
/// If we find an obviously non-foldable instruction, return true.
|
|
/// Add the ultimately found memory instructions to MemoryUses.
|
|
static bool FindAllMemoryUses(
|
|
Instruction *I,
|
|
SmallVectorImpl<std::pair<Instruction *, unsigned>> &MemoryUses,
|
|
SmallPtrSetImpl<Instruction *> &ConsideredInsts, const TargetLowering &TLI,
|
|
const TargetRegisterInfo &TRI, int SeenInsts = 0) {
|
|
// If we already considered this instruction, we're done.
|
|
if (!ConsideredInsts.insert(I).second)
|
|
return false;
|
|
|
|
// If this is an obviously unfoldable instruction, bail out.
|
|
if (!MightBeFoldableInst(I))
|
|
return true;
|
|
|
|
const bool OptSize = I->getFunction()->optForSize();
|
|
|
|
// Loop over all the uses, recursively processing them.
|
|
for (Use &U : I->uses()) {
|
|
// Conservatively return true if we're seeing a large number or a deep chain
|
|
// of users. This avoids excessive compilation times in pathological cases.
|
|
if (SeenInsts++ >= MaxMemoryUsesToScan)
|
|
return true;
|
|
|
|
Instruction *UserI = cast<Instruction>(U.getUser());
|
|
if (LoadInst *LI = dyn_cast<LoadInst>(UserI)) {
|
|
MemoryUses.push_back(std::make_pair(LI, U.getOperandNo()));
|
|
continue;
|
|
}
|
|
|
|
if (StoreInst *SI = dyn_cast<StoreInst>(UserI)) {
|
|
unsigned opNo = U.getOperandNo();
|
|
if (opNo != StoreInst::getPointerOperandIndex())
|
|
return true; // Storing addr, not into addr.
|
|
MemoryUses.push_back(std::make_pair(SI, opNo));
|
|
continue;
|
|
}
|
|
|
|
if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(UserI)) {
|
|
unsigned opNo = U.getOperandNo();
|
|
if (opNo != AtomicRMWInst::getPointerOperandIndex())
|
|
return true; // Storing addr, not into addr.
|
|
MemoryUses.push_back(std::make_pair(RMW, opNo));
|
|
continue;
|
|
}
|
|
|
|
if (AtomicCmpXchgInst *CmpX = dyn_cast<AtomicCmpXchgInst>(UserI)) {
|
|
unsigned opNo = U.getOperandNo();
|
|
if (opNo != AtomicCmpXchgInst::getPointerOperandIndex())
|
|
return true; // Storing addr, not into addr.
|
|
MemoryUses.push_back(std::make_pair(CmpX, opNo));
|
|
continue;
|
|
}
|
|
|
|
if (CallInst *CI = dyn_cast<CallInst>(UserI)) {
|
|
// If this is a cold call, we can sink the addressing calculation into
|
|
// the cold path. See optimizeCallInst
|
|
if (!OptSize && CI->hasFnAttr(Attribute::Cold))
|
|
continue;
|
|
|
|
InlineAsm *IA = dyn_cast<InlineAsm>(CI->getCalledValue());
|
|
if (!IA) return true;
|
|
|
|
// If this is a memory operand, we're cool, otherwise bail out.
|
|
if (!IsOperandAMemoryOperand(CI, IA, I, TLI, TRI))
|
|
return true;
|
|
continue;
|
|
}
|
|
|
|
if (FindAllMemoryUses(UserI, MemoryUses, ConsideredInsts, TLI, TRI,
|
|
SeenInsts))
|
|
return true;
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
/// Return true if Val is already known to be live at the use site that we're
|
|
/// folding it into. If so, there is no cost to include it in the addressing
|
|
/// mode. KnownLive1 and KnownLive2 are two values that we know are live at the
|
|
/// instruction already.
|
|
bool AddressingModeMatcher::valueAlreadyLiveAtInst(Value *Val,Value *KnownLive1,
|
|
Value *KnownLive2) {
|
|
// If Val is either of the known-live values, we know it is live!
|
|
if (Val == nullptr || Val == KnownLive1 || Val == KnownLive2)
|
|
return true;
|
|
|
|
// All values other than instructions and arguments (e.g. constants) are live.
|
|
if (!isa<Instruction>(Val) && !isa<Argument>(Val)) return true;
|
|
|
|
// If Val is a constant sized alloca in the entry block, it is live, this is
|
|
// true because it is just a reference to the stack/frame pointer, which is
|
|
// live for the whole function.
|
|
if (AllocaInst *AI = dyn_cast<AllocaInst>(Val))
|
|
if (AI->isStaticAlloca())
|
|
return true;
|
|
|
|
// Check to see if this value is already used in the memory instruction's
|
|
// block. If so, it's already live into the block at the very least, so we
|
|
// can reasonably fold it.
|
|
return Val->isUsedInBasicBlock(MemoryInst->getParent());
|
|
}
|
|
|
|
/// It is possible for the addressing mode of the machine to fold the specified
|
|
/// instruction into a load or store that ultimately uses it.
|
|
/// However, the specified instruction has multiple uses.
|
|
/// Given this, it may actually increase register pressure to fold it
|
|
/// into the load. For example, consider this code:
|
|
///
|
|
/// X = ...
|
|
/// Y = X+1
|
|
/// use(Y) -> nonload/store
|
|
/// Z = Y+1
|
|
/// load Z
|
|
///
|
|
/// In this case, Y has multiple uses, and can be folded into the load of Z
|
|
/// (yielding load [X+2]). However, doing this will cause both "X" and "X+1" to
|
|
/// be live at the use(Y) line. If we don't fold Y into load Z, we use one
|
|
/// fewer register. Since Y can't be folded into "use(Y)" we don't increase the
|
|
/// number of computations either.
|
|
///
|
|
/// Note that this (like most of CodeGenPrepare) is just a rough heuristic. If
|
|
/// X was live across 'load Z' for other reasons, we actually *would* want to
|
|
/// fold the addressing mode in the Z case. This would make Y die earlier.
|
|
bool AddressingModeMatcher::
|
|
isProfitableToFoldIntoAddressingMode(Instruction *I, ExtAddrMode &AMBefore,
|
|
ExtAddrMode &AMAfter) {
|
|
if (IgnoreProfitability) return true;
|
|
|
|
// AMBefore is the addressing mode before this instruction was folded into it,
|
|
// and AMAfter is the addressing mode after the instruction was folded. Get
|
|
// the set of registers referenced by AMAfter and subtract out those
|
|
// referenced by AMBefore: this is the set of values which folding in this
|
|
// address extends the lifetime of.
|
|
//
|
|
// Note that there are only two potential values being referenced here,
|
|
// BaseReg and ScaleReg (global addresses are always available, as are any
|
|
// folded immediates).
|
|
Value *BaseReg = AMAfter.BaseReg, *ScaledReg = AMAfter.ScaledReg;
|
|
|
|
// If the BaseReg or ScaledReg was referenced by the previous addrmode, their
|
|
// lifetime wasn't extended by adding this instruction.
|
|
if (valueAlreadyLiveAtInst(BaseReg, AMBefore.BaseReg, AMBefore.ScaledReg))
|
|
BaseReg = nullptr;
|
|
if (valueAlreadyLiveAtInst(ScaledReg, AMBefore.BaseReg, AMBefore.ScaledReg))
|
|
ScaledReg = nullptr;
|
|
|
|
// If folding this instruction (and it's subexprs) didn't extend any live
|
|
// ranges, we're ok with it.
|
|
if (!BaseReg && !ScaledReg)
|
|
return true;
|
|
|
|
// If all uses of this instruction can have the address mode sunk into them,
|
|
// we can remove the addressing mode and effectively trade one live register
|
|
// for another (at worst.) In this context, folding an addressing mode into
|
|
// the use is just a particularly nice way of sinking it.
|
|
SmallVector<std::pair<Instruction*,unsigned>, 16> MemoryUses;
|
|
SmallPtrSet<Instruction*, 16> ConsideredInsts;
|
|
if (FindAllMemoryUses(I, MemoryUses, ConsideredInsts, TLI, TRI))
|
|
return false; // Has a non-memory, non-foldable use!
|
|
|
|
// Now that we know that all uses of this instruction are part of a chain of
|
|
// computation involving only operations that could theoretically be folded
|
|
// into a memory use, loop over each of these memory operation uses and see
|
|
// if they could *actually* fold the instruction. The assumption is that
|
|
// addressing modes are cheap and that duplicating the computation involved
|
|
// many times is worthwhile, even on a fastpath. For sinking candidates
|
|
// (i.e. cold call sites), this serves as a way to prevent excessive code
|
|
// growth since most architectures have some reasonable small and fast way to
|
|
// compute an effective address. (i.e LEA on x86)
|
|
SmallVector<Instruction*, 32> MatchedAddrModeInsts;
|
|
for (unsigned i = 0, e = MemoryUses.size(); i != e; ++i) {
|
|
Instruction *User = MemoryUses[i].first;
|
|
unsigned OpNo = MemoryUses[i].second;
|
|
|
|
// Get the access type of this use. If the use isn't a pointer, we don't
|
|
// know what it accesses.
|
|
Value *Address = User->getOperand(OpNo);
|
|
PointerType *AddrTy = dyn_cast<PointerType>(Address->getType());
|
|
if (!AddrTy)
|
|
return false;
|
|
Type *AddressAccessTy = AddrTy->getElementType();
|
|
unsigned AS = AddrTy->getAddressSpace();
|
|
|
|
// Do a match against the root of this address, ignoring profitability. This
|
|
// will tell us if the addressing mode for the memory operation will
|
|
// *actually* cover the shared instruction.
|
|
ExtAddrMode Result;
|
|
std::pair<AssertingVH<GetElementPtrInst>, int64_t> LargeOffsetGEP(nullptr,
|
|
0);
|
|
TypePromotionTransaction::ConstRestorationPt LastKnownGood =
|
|
TPT.getRestorationPoint();
|
|
AddressingModeMatcher Matcher(
|
|
MatchedAddrModeInsts, TLI, TRI, AddressAccessTy, AS, MemoryInst, Result,
|
|
InsertedInsts, PromotedInsts, TPT, LargeOffsetGEP);
|
|
Matcher.IgnoreProfitability = true;
|
|
bool Success = Matcher.matchAddr(Address, 0);
|
|
(void)Success; assert(Success && "Couldn't select *anything*?");
|
|
|
|
// The match was to check the profitability, the changes made are not
|
|
// part of the original matcher. Therefore, they should be dropped
|
|
// otherwise the original matcher will not present the right state.
|
|
TPT.rollback(LastKnownGood);
|
|
|
|
// If the match didn't cover I, then it won't be shared by it.
|
|
if (!is_contained(MatchedAddrModeInsts, I))
|
|
return false;
|
|
|
|
MatchedAddrModeInsts.clear();
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
/// Return true if the specified values are defined in a
|
|
/// different basic block than BB.
|
|
static bool IsNonLocalValue(Value *V, BasicBlock *BB) {
|
|
if (Instruction *I = dyn_cast<Instruction>(V))
|
|
return I->getParent() != BB;
|
|
return false;
|
|
}
|
|
|
|
/// Sink addressing mode computation immediate before MemoryInst if doing so
|
|
/// can be done without increasing register pressure. The need for the
|
|
/// register pressure constraint means this can end up being an all or nothing
|
|
/// decision for all uses of the same addressing computation.
|
|
///
|
|
/// Load and Store Instructions often have addressing modes that can do
|
|
/// significant amounts of computation. As such, instruction selection will try
|
|
/// to get the load or store to do as much computation as possible for the
|
|
/// program. The problem is that isel can only see within a single block. As
|
|
/// such, we sink as much legal addressing mode work into the block as possible.
|
|
///
|
|
/// This method is used to optimize both load/store and inline asms with memory
|
|
/// operands. It's also used to sink addressing computations feeding into cold
|
|
/// call sites into their (cold) basic block.
|
|
///
|
|
/// The motivation for handling sinking into cold blocks is that doing so can
|
|
/// both enable other address mode sinking (by satisfying the register pressure
|
|
/// constraint above), and reduce register pressure globally (by removing the
|
|
/// addressing mode computation from the fast path entirely.).
|
|
bool CodeGenPrepare::optimizeMemoryInst(Instruction *MemoryInst, Value *Addr,
|
|
Type *AccessTy, unsigned AddrSpace) {
|
|
Value *Repl = Addr;
|
|
|
|
// Try to collapse single-value PHI nodes. This is necessary to undo
|
|
// unprofitable PRE transformations.
|
|
SmallVector<Value*, 8> worklist;
|
|
SmallPtrSet<Value*, 16> Visited;
|
|
worklist.push_back(Addr);
|
|
|
|
// Use a worklist to iteratively look through PHI and select nodes, and
|
|
// ensure that the addressing mode obtained from the non-PHI/select roots of
|
|
// the graph are compatible.
|
|
bool PhiOrSelectSeen = false;
|
|
SmallVector<Instruction*, 16> AddrModeInsts;
|
|
const SimplifyQuery SQ(*DL, TLInfo);
|
|
AddressingModeCombiner AddrModes(SQ, { Addr, MemoryInst->getParent() });
|
|
TypePromotionTransaction TPT(RemovedInsts);
|
|
TypePromotionTransaction::ConstRestorationPt LastKnownGood =
|
|
TPT.getRestorationPoint();
|
|
while (!worklist.empty()) {
|
|
Value *V = worklist.back();
|
|
worklist.pop_back();
|
|
|
|
// We allow traversing cyclic Phi nodes.
|
|
// In case of success after this loop we ensure that traversing through
|
|
// Phi nodes ends up with all cases to compute address of the form
|
|
// BaseGV + Base + Scale * Index + Offset
|
|
// where Scale and Offset are constans and BaseGV, Base and Index
|
|
// are exactly the same Values in all cases.
|
|
// It means that BaseGV, Scale and Offset dominate our memory instruction
|
|
// and have the same value as they had in address computation represented
|
|
// as Phi. So we can safely sink address computation to memory instruction.
|
|
if (!Visited.insert(V).second)
|
|
continue;
|
|
|
|
// For a PHI node, push all of its incoming values.
|
|
if (PHINode *P = dyn_cast<PHINode>(V)) {
|
|
for (Value *IncValue : P->incoming_values())
|
|
worklist.push_back(IncValue);
|
|
PhiOrSelectSeen = true;
|
|
continue;
|
|
}
|
|
// Similar for select.
|
|
if (SelectInst *SI = dyn_cast<SelectInst>(V)) {
|
|
worklist.push_back(SI->getFalseValue());
|
|
worklist.push_back(SI->getTrueValue());
|
|
PhiOrSelectSeen = true;
|
|
continue;
|
|
}
|
|
|
|
// For non-PHIs, determine the addressing mode being computed. Note that
|
|
// the result may differ depending on what other uses our candidate
|
|
// addressing instructions might have.
|
|
AddrModeInsts.clear();
|
|
std::pair<AssertingVH<GetElementPtrInst>, int64_t> LargeOffsetGEP(nullptr,
|
|
0);
|
|
ExtAddrMode NewAddrMode = AddressingModeMatcher::Match(
|
|
V, AccessTy, AddrSpace, MemoryInst, AddrModeInsts, *TLI, *TRI,
|
|
InsertedInsts, PromotedInsts, TPT, LargeOffsetGEP);
|
|
|
|
GetElementPtrInst *GEP = LargeOffsetGEP.first;
|
|
if (GEP && GEP->getParent() != MemoryInst->getParent() &&
|
|
!NewGEPBases.count(GEP)) {
|
|
// If splitting the underlying data structure can reduce the offset of a
|
|
// GEP, collect the GEP. Skip the GEPs that are the new bases of
|
|
// previously split data structures.
|
|
LargeOffsetGEPMap[GEP->getPointerOperand()].push_back(LargeOffsetGEP);
|
|
if (LargeOffsetGEPID.find(GEP) == LargeOffsetGEPID.end())
|
|
LargeOffsetGEPID[GEP] = LargeOffsetGEPID.size();
|
|
}
|
|
|
|
NewAddrMode.OriginalValue = V;
|
|
if (!AddrModes.addNewAddrMode(NewAddrMode))
|
|
break;
|
|
}
|
|
|
|
// Try to combine the AddrModes we've collected. If we couldn't collect any,
|
|
// or we have multiple but either couldn't combine them or combining them
|
|
// wouldn't do anything useful, bail out now.
|
|
if (!AddrModes.combineAddrModes()) {
|
|
TPT.rollback(LastKnownGood);
|
|
return false;
|
|
}
|
|
TPT.commit();
|
|
|
|
// Get the combined AddrMode (or the only AddrMode, if we only had one).
|
|
ExtAddrMode AddrMode = AddrModes.getAddrMode();
|
|
|
|
// If all the instructions matched are already in this BB, don't do anything.
|
|
// If we saw a Phi node then it is not local definitely, and if we saw a select
|
|
// then we want to push the address calculation past it even if it's already
|
|
// in this BB.
|
|
if (!PhiOrSelectSeen && none_of(AddrModeInsts, [&](Value *V) {
|
|
return IsNonLocalValue(V, MemoryInst->getParent());
|
|
})) {
|
|
LLVM_DEBUG(dbgs() << "CGP: Found local addrmode: " << AddrMode
|
|
<< "\n");
|
|
return false;
|
|
}
|
|
|
|
// Insert this computation right after this user. Since our caller is
|
|
// scanning from the top of the BB to the bottom, reuse of the expr are
|
|
// guaranteed to happen later.
|
|
IRBuilder<> Builder(MemoryInst);
|
|
|
|
// Now that we determined the addressing expression we want to use and know
|
|
// that we have to sink it into this block. Check to see if we have already
|
|
// done this for some other load/store instr in this block. If so, reuse
|
|
// the computation. Before attempting reuse, check if the address is valid
|
|
// as it may have been erased.
|
|
|
|
WeakTrackingVH SunkAddrVH = SunkAddrs[Addr];
|
|
|
|
Value * SunkAddr = SunkAddrVH.pointsToAliveValue() ? SunkAddrVH : nullptr;
|
|
if (SunkAddr) {
|
|
LLVM_DEBUG(dbgs() << "CGP: Reusing nonlocal addrmode: " << AddrMode
|
|
<< " for " << *MemoryInst << "\n");
|
|
if (SunkAddr->getType() != Addr->getType())
|
|
SunkAddr = Builder.CreatePointerCast(SunkAddr, Addr->getType());
|
|
} else if (AddrSinkUsingGEPs ||
|
|
(!AddrSinkUsingGEPs.getNumOccurrences() && TM && TTI->useAA())) {
|
|
// By default, we use the GEP-based method when AA is used later. This
|
|
// prevents new inttoptr/ptrtoint pairs from degrading AA capabilities.
|
|
LLVM_DEBUG(dbgs() << "CGP: SINKING nonlocal addrmode: " << AddrMode
|
|
<< " for " << *MemoryInst << "\n");
|
|
Type *IntPtrTy = DL->getIntPtrType(Addr->getType());
|
|
Value *ResultPtr = nullptr, *ResultIndex = nullptr;
|
|
|
|
// First, find the pointer.
|
|
if (AddrMode.BaseReg && AddrMode.BaseReg->getType()->isPointerTy()) {
|
|
ResultPtr = AddrMode.BaseReg;
|
|
AddrMode.BaseReg = nullptr;
|
|
}
|
|
|
|
if (AddrMode.Scale && AddrMode.ScaledReg->getType()->isPointerTy()) {
|
|
// We can't add more than one pointer together, nor can we scale a
|
|
// pointer (both of which seem meaningless).
|
|
if (ResultPtr || AddrMode.Scale != 1)
|
|
return false;
|
|
|
|
ResultPtr = AddrMode.ScaledReg;
|
|
AddrMode.Scale = 0;
|
|
}
|
|
|
|
// It is only safe to sign extend the BaseReg if we know that the math
|
|
// required to create it did not overflow before we extend it. Since
|
|
// the original IR value was tossed in favor of a constant back when
|
|
// the AddrMode was created we need to bail out gracefully if widths
|
|
// do not match instead of extending it.
|
|
//
|
|
// (See below for code to add the scale.)
|
|
if (AddrMode.Scale) {
|
|
Type *ScaledRegTy = AddrMode.ScaledReg->getType();
|
|
if (cast<IntegerType>(IntPtrTy)->getBitWidth() >
|
|
cast<IntegerType>(ScaledRegTy)->getBitWidth())
|
|
return false;
|
|
}
|
|
|
|
if (AddrMode.BaseGV) {
|
|
if (ResultPtr)
|
|
return false;
|
|
|
|
ResultPtr = AddrMode.BaseGV;
|
|
}
|
|
|
|
// If the real base value actually came from an inttoptr, then the matcher
|
|
// will look through it and provide only the integer value. In that case,
|
|
// use it here.
|
|
if (!DL->isNonIntegralPointerType(Addr->getType())) {
|
|
if (!ResultPtr && AddrMode.BaseReg) {
|
|
ResultPtr = Builder.CreateIntToPtr(AddrMode.BaseReg, Addr->getType(),
|
|
"sunkaddr");
|
|
AddrMode.BaseReg = nullptr;
|
|
} else if (!ResultPtr && AddrMode.Scale == 1) {
|
|
ResultPtr = Builder.CreateIntToPtr(AddrMode.ScaledReg, Addr->getType(),
|
|
"sunkaddr");
|
|
AddrMode.Scale = 0;
|
|
}
|
|
}
|
|
|
|
if (!ResultPtr &&
|
|
!AddrMode.BaseReg && !AddrMode.Scale && !AddrMode.BaseOffs) {
|
|
SunkAddr = Constant::getNullValue(Addr->getType());
|
|
} else if (!ResultPtr) {
|
|
return false;
|
|
} else {
|
|
Type *I8PtrTy =
|
|
Builder.getInt8PtrTy(Addr->getType()->getPointerAddressSpace());
|
|
Type *I8Ty = Builder.getInt8Ty();
|
|
|
|
// Start with the base register. Do this first so that subsequent address
|
|
// matching finds it last, which will prevent it from trying to match it
|
|
// as the scaled value in case it happens to be a mul. That would be
|
|
// problematic if we've sunk a different mul for the scale, because then
|
|
// we'd end up sinking both muls.
|
|
if (AddrMode.BaseReg) {
|
|
Value *V = AddrMode.BaseReg;
|
|
if (V->getType() != IntPtrTy)
|
|
V = Builder.CreateIntCast(V, IntPtrTy, /*isSigned=*/true, "sunkaddr");
|
|
|
|
ResultIndex = V;
|
|
}
|
|
|
|
// Add the scale value.
|
|
if (AddrMode.Scale) {
|
|
Value *V = AddrMode.ScaledReg;
|
|
if (V->getType() == IntPtrTy) {
|
|
// done.
|
|
} else {
|
|
assert(cast<IntegerType>(IntPtrTy)->getBitWidth() <
|
|
cast<IntegerType>(V->getType())->getBitWidth() &&
|
|
"We can't transform if ScaledReg is too narrow");
|
|
V = Builder.CreateTrunc(V, IntPtrTy, "sunkaddr");
|
|
}
|
|
|
|
if (AddrMode.Scale != 1)
|
|
V = Builder.CreateMul(V, ConstantInt::get(IntPtrTy, AddrMode.Scale),
|
|
"sunkaddr");
|
|
if (ResultIndex)
|
|
ResultIndex = Builder.CreateAdd(ResultIndex, V, "sunkaddr");
|
|
else
|
|
ResultIndex = V;
|
|
}
|
|
|
|
// Add in the Base Offset if present.
|
|
if (AddrMode.BaseOffs) {
|
|
Value *V = ConstantInt::get(IntPtrTy, AddrMode.BaseOffs);
|
|
if (ResultIndex) {
|
|
// We need to add this separately from the scale above to help with
|
|
// SDAG consecutive load/store merging.
|
|
if (ResultPtr->getType() != I8PtrTy)
|
|
ResultPtr = Builder.CreatePointerCast(ResultPtr, I8PtrTy);
|
|
ResultPtr = Builder.CreateGEP(I8Ty, ResultPtr, ResultIndex, "sunkaddr");
|
|
}
|
|
|
|
ResultIndex = V;
|
|
}
|
|
|
|
if (!ResultIndex) {
|
|
SunkAddr = ResultPtr;
|
|
} else {
|
|
if (ResultPtr->getType() != I8PtrTy)
|
|
ResultPtr = Builder.CreatePointerCast(ResultPtr, I8PtrTy);
|
|
SunkAddr = Builder.CreateGEP(I8Ty, ResultPtr, ResultIndex, "sunkaddr");
|
|
}
|
|
|
|
if (SunkAddr->getType() != Addr->getType())
|
|
SunkAddr = Builder.CreatePointerCast(SunkAddr, Addr->getType());
|
|
}
|
|
} else {
|
|
// We'd require a ptrtoint/inttoptr down the line, which we can't do for
|
|
// non-integral pointers, so in that case bail out now.
|
|
Type *BaseTy = AddrMode.BaseReg ? AddrMode.BaseReg->getType() : nullptr;
|
|
Type *ScaleTy = AddrMode.Scale ? AddrMode.ScaledReg->getType() : nullptr;
|
|
PointerType *BasePtrTy = dyn_cast_or_null<PointerType>(BaseTy);
|
|
PointerType *ScalePtrTy = dyn_cast_or_null<PointerType>(ScaleTy);
|
|
if (DL->isNonIntegralPointerType(Addr->getType()) ||
|
|
(BasePtrTy && DL->isNonIntegralPointerType(BasePtrTy)) ||
|
|
(ScalePtrTy && DL->isNonIntegralPointerType(ScalePtrTy)) ||
|
|
(AddrMode.BaseGV &&
|
|
DL->isNonIntegralPointerType(AddrMode.BaseGV->getType())))
|
|
return false;
|
|
|
|
LLVM_DEBUG(dbgs() << "CGP: SINKING nonlocal addrmode: " << AddrMode
|
|
<< " for " << *MemoryInst << "\n");
|
|
Type *IntPtrTy = DL->getIntPtrType(Addr->getType());
|
|
Value *Result = nullptr;
|
|
|
|
// Start with the base register. Do this first so that subsequent address
|
|
// matching finds it last, which will prevent it from trying to match it
|
|
// as the scaled value in case it happens to be a mul. That would be
|
|
// problematic if we've sunk a different mul for the scale, because then
|
|
// we'd end up sinking both muls.
|
|
if (AddrMode.BaseReg) {
|
|
Value *V = AddrMode.BaseReg;
|
|
if (V->getType()->isPointerTy())
|
|
V = Builder.CreatePtrToInt(V, IntPtrTy, "sunkaddr");
|
|
if (V->getType() != IntPtrTy)
|
|
V = Builder.CreateIntCast(V, IntPtrTy, /*isSigned=*/true, "sunkaddr");
|
|
Result = V;
|
|
}
|
|
|
|
// Add the scale value.
|
|
if (AddrMode.Scale) {
|
|
Value *V = AddrMode.ScaledReg;
|
|
if (V->getType() == IntPtrTy) {
|
|
// done.
|
|
} else if (V->getType()->isPointerTy()) {
|
|
V = Builder.CreatePtrToInt(V, IntPtrTy, "sunkaddr");
|
|
} else if (cast<IntegerType>(IntPtrTy)->getBitWidth() <
|
|
cast<IntegerType>(V->getType())->getBitWidth()) {
|
|
V = Builder.CreateTrunc(V, IntPtrTy, "sunkaddr");
|
|
} else {
|
|
// It is only safe to sign extend the BaseReg if we know that the math
|
|
// required to create it did not overflow before we extend it. Since
|
|
// the original IR value was tossed in favor of a constant back when
|
|
// the AddrMode was created we need to bail out gracefully if widths
|
|
// do not match instead of extending it.
|
|
Instruction *I = dyn_cast_or_null<Instruction>(Result);
|
|
if (I && (Result != AddrMode.BaseReg))
|
|
I->eraseFromParent();
|
|
return false;
|
|
}
|
|
if (AddrMode.Scale != 1)
|
|
V = Builder.CreateMul(V, ConstantInt::get(IntPtrTy, AddrMode.Scale),
|
|
"sunkaddr");
|
|
if (Result)
|
|
Result = Builder.CreateAdd(Result, V, "sunkaddr");
|
|
else
|
|
Result = V;
|
|
}
|
|
|
|
// Add in the BaseGV if present.
|
|
if (AddrMode.BaseGV) {
|
|
Value *V = Builder.CreatePtrToInt(AddrMode.BaseGV, IntPtrTy, "sunkaddr");
|
|
if (Result)
|
|
Result = Builder.CreateAdd(Result, V, "sunkaddr");
|
|
else
|
|
Result = V;
|
|
}
|
|
|
|
// Add in the Base Offset if present.
|
|
if (AddrMode.BaseOffs) {
|
|
Value *V = ConstantInt::get(IntPtrTy, AddrMode.BaseOffs);
|
|
if (Result)
|
|
Result = Builder.CreateAdd(Result, V, "sunkaddr");
|
|
else
|
|
Result = V;
|
|
}
|
|
|
|
if (!Result)
|
|
SunkAddr = Constant::getNullValue(Addr->getType());
|
|
else
|
|
SunkAddr = Builder.CreateIntToPtr(Result, Addr->getType(), "sunkaddr");
|
|
}
|
|
|
|
MemoryInst->replaceUsesOfWith(Repl, SunkAddr);
|
|
// Store the newly computed address into the cache. In the case we reused a
|
|
// value, this should be idempotent.
|
|
SunkAddrs[Addr] = WeakTrackingVH(SunkAddr);
|
|
|
|
// If we have no uses, recursively delete the value and all dead instructions
|
|
// using it.
|
|
if (Repl->use_empty()) {
|
|
// This can cause recursive deletion, which can invalidate our iterator.
|
|
// Use a WeakTrackingVH to hold onto it in case this happens.
|
|
Value *CurValue = &*CurInstIterator;
|
|
WeakTrackingVH IterHandle(CurValue);
|
|
BasicBlock *BB = CurInstIterator->getParent();
|
|
|
|
RecursivelyDeleteTriviallyDeadInstructions(Repl, TLInfo);
|
|
|
|
if (IterHandle != CurValue) {
|
|
// If the iterator instruction was recursively deleted, start over at the
|
|
// start of the block.
|
|
CurInstIterator = BB->begin();
|
|
SunkAddrs.clear();
|
|
}
|
|
}
|
|
++NumMemoryInsts;
|
|
return true;
|
|
}
|
|
|
|
/// If there are any memory operands, use OptimizeMemoryInst to sink their
|
|
/// address computing into the block when possible / profitable.
|
|
bool CodeGenPrepare::optimizeInlineAsmInst(CallInst *CS) {
|
|
bool MadeChange = false;
|
|
|
|
const TargetRegisterInfo *TRI =
|
|
TM->getSubtargetImpl(*CS->getFunction())->getRegisterInfo();
|
|
TargetLowering::AsmOperandInfoVector TargetConstraints =
|
|
TLI->ParseConstraints(*DL, TRI, CS);
|
|
unsigned ArgNo = 0;
|
|
for (unsigned i = 0, e = TargetConstraints.size(); i != e; ++i) {
|
|
TargetLowering::AsmOperandInfo &OpInfo = TargetConstraints[i];
|
|
|
|
// Compute the constraint code and ConstraintType to use.
|
|
TLI->ComputeConstraintToUse(OpInfo, SDValue());
|
|
|
|
if (OpInfo.ConstraintType == TargetLowering::C_Memory &&
|
|
OpInfo.isIndirect) {
|
|
Value *OpVal = CS->getArgOperand(ArgNo++);
|
|
MadeChange |= optimizeMemoryInst(CS, OpVal, OpVal->getType(), ~0u);
|
|
} else if (OpInfo.Type == InlineAsm::isInput)
|
|
ArgNo++;
|
|
}
|
|
|
|
return MadeChange;
|
|
}
|
|
|
|
/// Check if all the uses of \p Val are equivalent (or free) zero or
|
|
/// sign extensions.
|
|
static bool hasSameExtUse(Value *Val, const TargetLowering &TLI) {
|
|
assert(!Val->use_empty() && "Input must have at least one use");
|
|
const Instruction *FirstUser = cast<Instruction>(*Val->user_begin());
|
|
bool IsSExt = isa<SExtInst>(FirstUser);
|
|
Type *ExtTy = FirstUser->getType();
|
|
for (const User *U : Val->users()) {
|
|
const Instruction *UI = cast<Instruction>(U);
|
|
if ((IsSExt && !isa<SExtInst>(UI)) || (!IsSExt && !isa<ZExtInst>(UI)))
|
|
return false;
|
|
Type *CurTy = UI->getType();
|
|
// Same input and output types: Same instruction after CSE.
|
|
if (CurTy == ExtTy)
|
|
continue;
|
|
|
|
// If IsSExt is true, we are in this situation:
|
|
// a = Val
|
|
// b = sext ty1 a to ty2
|
|
// c = sext ty1 a to ty3
|
|
// Assuming ty2 is shorter than ty3, this could be turned into:
|
|
// a = Val
|
|
// b = sext ty1 a to ty2
|
|
// c = sext ty2 b to ty3
|
|
// However, the last sext is not free.
|
|
if (IsSExt)
|
|
return false;
|
|
|
|
// This is a ZExt, maybe this is free to extend from one type to another.
|
|
// In that case, we would not account for a different use.
|
|
Type *NarrowTy;
|
|
Type *LargeTy;
|
|
if (ExtTy->getScalarType()->getIntegerBitWidth() >
|
|
CurTy->getScalarType()->getIntegerBitWidth()) {
|
|
NarrowTy = CurTy;
|
|
LargeTy = ExtTy;
|
|
} else {
|
|
NarrowTy = ExtTy;
|
|
LargeTy = CurTy;
|
|
}
|
|
|
|
if (!TLI.isZExtFree(NarrowTy, LargeTy))
|
|
return false;
|
|
}
|
|
// All uses are the same or can be derived from one another for free.
|
|
return true;
|
|
}
|
|
|
|
/// Try to speculatively promote extensions in \p Exts and continue
|
|
/// promoting through newly promoted operands recursively as far as doing so is
|
|
/// profitable. Save extensions profitably moved up, in \p ProfitablyMovedExts.
|
|
/// When some promotion happened, \p TPT contains the proper state to revert
|
|
/// them.
|
|
///
|
|
/// \return true if some promotion happened, false otherwise.
|
|
bool CodeGenPrepare::tryToPromoteExts(
|
|
TypePromotionTransaction &TPT, const SmallVectorImpl<Instruction *> &Exts,
|
|
SmallVectorImpl<Instruction *> &ProfitablyMovedExts,
|
|
unsigned CreatedInstsCost) {
|
|
bool Promoted = false;
|
|
|
|
// Iterate over all the extensions to try to promote them.
|
|
for (auto I : Exts) {
|
|
// Early check if we directly have ext(load).
|
|
if (isa<LoadInst>(I->getOperand(0))) {
|
|
ProfitablyMovedExts.push_back(I);
|
|
continue;
|
|
}
|
|
|
|
// Check whether or not we want to do any promotion. The reason we have
|
|
// this check inside the for loop is to catch the case where an extension
|
|
// is directly fed by a load because in such case the extension can be moved
|
|
// up without any promotion on its operands.
|
|
if (!TLI || !TLI->enableExtLdPromotion() || DisableExtLdPromotion)
|
|
return false;
|
|
|
|
// Get the action to perform the promotion.
|
|
TypePromotionHelper::Action TPH =
|
|
TypePromotionHelper::getAction(I, InsertedInsts, *TLI, PromotedInsts);
|
|
// Check if we can promote.
|
|
if (!TPH) {
|
|
// Save the current extension as we cannot move up through its operand.
|
|
ProfitablyMovedExts.push_back(I);
|
|
continue;
|
|
}
|
|
|
|
// Save the current state.
|
|
TypePromotionTransaction::ConstRestorationPt LastKnownGood =
|
|
TPT.getRestorationPoint();
|
|
SmallVector<Instruction *, 4> NewExts;
|
|
unsigned NewCreatedInstsCost = 0;
|
|
unsigned ExtCost = !TLI->isExtFree(I);
|
|
// Promote.
|
|
Value *PromotedVal = TPH(I, TPT, PromotedInsts, NewCreatedInstsCost,
|
|
&NewExts, nullptr, *TLI);
|
|
assert(PromotedVal &&
|
|
"TypePromotionHelper should have filtered out those cases");
|
|
|
|
// We would be able to merge only one extension in a load.
|
|
// Therefore, if we have more than 1 new extension we heuristically
|
|
// cut this search path, because it means we degrade the code quality.
|
|
// With exactly 2, the transformation is neutral, because we will merge
|
|
// one extension but leave one. However, we optimistically keep going,
|
|
// because the new extension may be removed too.
|
|
long long TotalCreatedInstsCost = CreatedInstsCost + NewCreatedInstsCost;
|
|
// FIXME: It would be possible to propagate a negative value instead of
|
|
// conservatively ceiling it to 0.
|
|
TotalCreatedInstsCost =
|
|
std::max((long long)0, (TotalCreatedInstsCost - ExtCost));
|
|
if (!StressExtLdPromotion &&
|
|
(TotalCreatedInstsCost > 1 ||
|
|
!isPromotedInstructionLegal(*TLI, *DL, PromotedVal))) {
|
|
// This promotion is not profitable, rollback to the previous state, and
|
|
// save the current extension in ProfitablyMovedExts as the latest
|
|
// speculative promotion turned out to be unprofitable.
|
|
TPT.rollback(LastKnownGood);
|
|
ProfitablyMovedExts.push_back(I);
|
|
continue;
|
|
}
|
|
// Continue promoting NewExts as far as doing so is profitable.
|
|
SmallVector<Instruction *, 2> NewlyMovedExts;
|
|
(void)tryToPromoteExts(TPT, NewExts, NewlyMovedExts, TotalCreatedInstsCost);
|
|
bool NewPromoted = false;
|
|
for (auto ExtInst : NewlyMovedExts) {
|
|
Instruction *MovedExt = cast<Instruction>(ExtInst);
|
|
Value *ExtOperand = MovedExt->getOperand(0);
|
|
// If we have reached to a load, we need this extra profitability check
|
|
// as it could potentially be merged into an ext(load).
|
|
if (isa<LoadInst>(ExtOperand) &&
|
|
!(StressExtLdPromotion || NewCreatedInstsCost <= ExtCost ||
|
|
(ExtOperand->hasOneUse() || hasSameExtUse(ExtOperand, *TLI))))
|
|
continue;
|
|
|
|
ProfitablyMovedExts.push_back(MovedExt);
|
|
NewPromoted = true;
|
|
}
|
|
|
|
// If none of speculative promotions for NewExts is profitable, rollback
|
|
// and save the current extension (I) as the last profitable extension.
|
|
if (!NewPromoted) {
|
|
TPT.rollback(LastKnownGood);
|
|
ProfitablyMovedExts.push_back(I);
|
|
continue;
|
|
}
|
|
// The promotion is profitable.
|
|
Promoted = true;
|
|
}
|
|
return Promoted;
|
|
}
|
|
|
|
/// Merging redundant sexts when one is dominating the other.
|
|
bool CodeGenPrepare::mergeSExts(Function &F) {
|
|
DominatorTree DT(F);
|
|
bool Changed = false;
|
|
for (auto &Entry : ValToSExtendedUses) {
|
|
SExts &Insts = Entry.second;
|
|
SExts CurPts;
|
|
for (Instruction *Inst : Insts) {
|
|
if (RemovedInsts.count(Inst) || !isa<SExtInst>(Inst) ||
|
|
Inst->getOperand(0) != Entry.first)
|
|
continue;
|
|
bool inserted = false;
|
|
for (auto &Pt : CurPts) {
|
|
if (DT.dominates(Inst, Pt)) {
|
|
Pt->replaceAllUsesWith(Inst);
|
|
RemovedInsts.insert(Pt);
|
|
Pt->removeFromParent();
|
|
Pt = Inst;
|
|
inserted = true;
|
|
Changed = true;
|
|
break;
|
|
}
|
|
if (!DT.dominates(Pt, Inst))
|
|
// Give up if we need to merge in a common dominator as the
|
|
// experiments show it is not profitable.
|
|
continue;
|
|
Inst->replaceAllUsesWith(Pt);
|
|
RemovedInsts.insert(Inst);
|
|
Inst->removeFromParent();
|
|
inserted = true;
|
|
Changed = true;
|
|
break;
|
|
}
|
|
if (!inserted)
|
|
CurPts.push_back(Inst);
|
|
}
|
|
}
|
|
return Changed;
|
|
}
|
|
|
|
// Spliting large data structures so that the GEPs accessing them can have
|
|
// smaller offsets so that they can be sunk to the same blocks as their users.
|
|
// For example, a large struct starting from %base is splitted into two parts
|
|
// where the second part starts from %new_base.
|
|
//
|
|
// Before:
|
|
// BB0:
|
|
// %base =
|
|
//
|
|
// BB1:
|
|
// %gep0 = gep %base, off0
|
|
// %gep1 = gep %base, off1
|
|
// %gep2 = gep %base, off2
|
|
//
|
|
// BB2:
|
|
// %load1 = load %gep0
|
|
// %load2 = load %gep1
|
|
// %load3 = load %gep2
|
|
//
|
|
// After:
|
|
// BB0:
|
|
// %base =
|
|
// %new_base = gep %base, off0
|
|
//
|
|
// BB1:
|
|
// %new_gep0 = %new_base
|
|
// %new_gep1 = gep %new_base, off1 - off0
|
|
// %new_gep2 = gep %new_base, off2 - off0
|
|
//
|
|
// BB2:
|
|
// %load1 = load i32, i32* %new_gep0
|
|
// %load2 = load i32, i32* %new_gep1
|
|
// %load3 = load i32, i32* %new_gep2
|
|
//
|
|
// %new_gep1 and %new_gep2 can be sunk to BB2 now after the splitting because
|
|
// their offsets are smaller enough to fit into the addressing mode.
|
|
bool CodeGenPrepare::splitLargeGEPOffsets() {
|
|
bool Changed = false;
|
|
for (auto &Entry : LargeOffsetGEPMap) {
|
|
Value *OldBase = Entry.first;
|
|
SmallVectorImpl<std::pair<AssertingVH<GetElementPtrInst>, int64_t>>
|
|
&LargeOffsetGEPs = Entry.second;
|
|
auto compareGEPOffset =
|
|
[&](const std::pair<GetElementPtrInst *, int64_t> &LHS,
|
|
const std::pair<GetElementPtrInst *, int64_t> &RHS) {
|
|
if (LHS.first == RHS.first)
|
|
return false;
|
|
if (LHS.second != RHS.second)
|
|
return LHS.second < RHS.second;
|
|
return LargeOffsetGEPID[LHS.first] < LargeOffsetGEPID[RHS.first];
|
|
};
|
|
// Sorting all the GEPs of the same data structures based on the offsets.
|
|
llvm::sort(LargeOffsetGEPs.begin(), LargeOffsetGEPs.end(),
|
|
compareGEPOffset);
|
|
LargeOffsetGEPs.erase(
|
|
std::unique(LargeOffsetGEPs.begin(), LargeOffsetGEPs.end()),
|
|
LargeOffsetGEPs.end());
|
|
// Skip if all the GEPs have the same offsets.
|
|
if (LargeOffsetGEPs.front().second == LargeOffsetGEPs.back().second)
|
|
continue;
|
|
GetElementPtrInst *BaseGEP = LargeOffsetGEPs.begin()->first;
|
|
int64_t BaseOffset = LargeOffsetGEPs.begin()->second;
|
|
Value *NewBaseGEP = nullptr;
|
|
|
|
auto LargeOffsetGEP = LargeOffsetGEPs.begin();
|
|
while (LargeOffsetGEP != LargeOffsetGEPs.end()) {
|
|
GetElementPtrInst *GEP = LargeOffsetGEP->first;
|
|
int64_t Offset = LargeOffsetGEP->second;
|
|
if (Offset != BaseOffset) {
|
|
TargetLowering::AddrMode AddrMode;
|
|
AddrMode.BaseOffs = Offset - BaseOffset;
|
|
// The result type of the GEP might not be the type of the memory
|
|
// access.
|
|
if (!TLI->isLegalAddressingMode(*DL, AddrMode,
|
|
GEP->getResultElementType(),
|
|
GEP->getAddressSpace())) {
|
|
// We need to create a new base if the offset to the current base is
|
|
// too large to fit into the addressing mode. So, a very large struct
|
|
// may be splitted into several parts.
|
|
BaseGEP = GEP;
|
|
BaseOffset = Offset;
|
|
NewBaseGEP = nullptr;
|
|
}
|
|
}
|
|
|
|
// Generate a new GEP to replace the current one.
|
|
IRBuilder<> Builder(GEP);
|
|
Type *IntPtrTy = DL->getIntPtrType(GEP->getType());
|
|
Type *I8PtrTy =
|
|
Builder.getInt8PtrTy(GEP->getType()->getPointerAddressSpace());
|
|
Type *I8Ty = Builder.getInt8Ty();
|
|
|
|
if (!NewBaseGEP) {
|
|
// Create a new base if we don't have one yet. Find the insertion
|
|
// pointer for the new base first.
|
|
BasicBlock::iterator NewBaseInsertPt;
|
|
BasicBlock *NewBaseInsertBB;
|
|
if (auto *BaseI = dyn_cast<Instruction>(OldBase)) {
|
|
// If the base of the struct is an instruction, the new base will be
|
|
// inserted close to it.
|
|
NewBaseInsertBB = BaseI->getParent();
|
|
if (isa<PHINode>(BaseI))
|
|
NewBaseInsertPt = NewBaseInsertBB->getFirstInsertionPt();
|
|
else if (InvokeInst *Invoke = dyn_cast<InvokeInst>(BaseI)) {
|
|
NewBaseInsertBB =
|
|
SplitEdge(NewBaseInsertBB, Invoke->getNormalDest());
|
|
NewBaseInsertPt = NewBaseInsertBB->getFirstInsertionPt();
|
|
} else
|
|
NewBaseInsertPt = std::next(BaseI->getIterator());
|
|
} else {
|
|
// If the current base is an argument or global value, the new base
|
|
// will be inserted to the entry block.
|
|
NewBaseInsertBB = &BaseGEP->getFunction()->getEntryBlock();
|
|
NewBaseInsertPt = NewBaseInsertBB->getFirstInsertionPt();
|
|
}
|
|
IRBuilder<> NewBaseBuilder(NewBaseInsertBB, NewBaseInsertPt);
|
|
// Create a new base.
|
|
Value *BaseIndex = ConstantInt::get(IntPtrTy, BaseOffset);
|
|
NewBaseGEP = OldBase;
|
|
if (NewBaseGEP->getType() != I8PtrTy)
|
|
NewBaseGEP = NewBaseBuilder.CreatePointerCast(NewBaseGEP, I8PtrTy);
|
|
NewBaseGEP =
|
|
NewBaseBuilder.CreateGEP(I8Ty, NewBaseGEP, BaseIndex, "splitgep");
|
|
NewGEPBases.insert(NewBaseGEP);
|
|
}
|
|
|
|
Value *NewGEP = NewBaseGEP;
|
|
if (Offset == BaseOffset) {
|
|
if (GEP->getType() != I8PtrTy)
|
|
NewGEP = Builder.CreatePointerCast(NewGEP, GEP->getType());
|
|
} else {
|
|
// Calculate the new offset for the new GEP.
|
|
Value *Index = ConstantInt::get(IntPtrTy, Offset - BaseOffset);
|
|
NewGEP = Builder.CreateGEP(I8Ty, NewBaseGEP, Index);
|
|
|
|
if (GEP->getType() != I8PtrTy)
|
|
NewGEP = Builder.CreatePointerCast(NewGEP, GEP->getType());
|
|
}
|
|
GEP->replaceAllUsesWith(NewGEP);
|
|
LargeOffsetGEPID.erase(GEP);
|
|
LargeOffsetGEP = LargeOffsetGEPs.erase(LargeOffsetGEP);
|
|
GEP->eraseFromParent();
|
|
Changed = true;
|
|
}
|
|
}
|
|
return Changed;
|
|
}
|
|
|
|
/// Return true, if an ext(load) can be formed from an extension in
|
|
/// \p MovedExts.
|
|
bool CodeGenPrepare::canFormExtLd(
|
|
const SmallVectorImpl<Instruction *> &MovedExts, LoadInst *&LI,
|
|
Instruction *&Inst, bool HasPromoted) {
|
|
for (auto *MovedExtInst : MovedExts) {
|
|
if (isa<LoadInst>(MovedExtInst->getOperand(0))) {
|
|
LI = cast<LoadInst>(MovedExtInst->getOperand(0));
|
|
Inst = MovedExtInst;
|
|
break;
|
|
}
|
|
}
|
|
if (!LI)
|
|
return false;
|
|
|
|
// If they're already in the same block, there's nothing to do.
|
|
// Make the cheap checks first if we did not promote.
|
|
// If we promoted, we need to check if it is indeed profitable.
|
|
if (!HasPromoted && LI->getParent() == Inst->getParent())
|
|
return false;
|
|
|
|
return TLI->isExtLoad(LI, Inst, *DL);
|
|
}
|
|
|
|
/// Move a zext or sext fed by a load into the same basic block as the load,
|
|
/// unless conditions are unfavorable. This allows SelectionDAG to fold the
|
|
/// extend into the load.
|
|
///
|
|
/// E.g.,
|
|
/// \code
|
|
/// %ld = load i32* %addr
|
|
/// %add = add nuw i32 %ld, 4
|
|
/// %zext = zext i32 %add to i64
|
|
// \endcode
|
|
/// =>
|
|
/// \code
|
|
/// %ld = load i32* %addr
|
|
/// %zext = zext i32 %ld to i64
|
|
/// %add = add nuw i64 %zext, 4
|
|
/// \encode
|
|
/// Note that the promotion in %add to i64 is done in tryToPromoteExts(), which
|
|
/// allow us to match zext(load i32*) to i64.
|
|
///
|
|
/// Also, try to promote the computations used to obtain a sign extended
|
|
/// value used into memory accesses.
|
|
/// E.g.,
|
|
/// \code
|
|
/// a = add nsw i32 b, 3
|
|
/// d = sext i32 a to i64
|
|
/// e = getelementptr ..., i64 d
|
|
/// \endcode
|
|
/// =>
|
|
/// \code
|
|
/// f = sext i32 b to i64
|
|
/// a = add nsw i64 f, 3
|
|
/// e = getelementptr ..., i64 a
|
|
/// \endcode
|
|
///
|
|
/// \p Inst[in/out] the extension may be modified during the process if some
|
|
/// promotions apply.
|
|
bool CodeGenPrepare::optimizeExt(Instruction *&Inst) {
|
|
// ExtLoad formation and address type promotion infrastructure requires TLI to
|
|
// be effective.
|
|
if (!TLI)
|
|
return false;
|
|
|
|
bool AllowPromotionWithoutCommonHeader = false;
|
|
/// See if it is an interesting sext operations for the address type
|
|
/// promotion before trying to promote it, e.g., the ones with the right
|
|
/// type and used in memory accesses.
|
|
bool ATPConsiderable = TTI->shouldConsiderAddressTypePromotion(
|
|
*Inst, AllowPromotionWithoutCommonHeader);
|
|
TypePromotionTransaction TPT(RemovedInsts);
|
|
TypePromotionTransaction::ConstRestorationPt LastKnownGood =
|
|
TPT.getRestorationPoint();
|
|
SmallVector<Instruction *, 1> Exts;
|
|
SmallVector<Instruction *, 2> SpeculativelyMovedExts;
|
|
Exts.push_back(Inst);
|
|
|
|
bool HasPromoted = tryToPromoteExts(TPT, Exts, SpeculativelyMovedExts);
|
|
|
|
// Look for a load being extended.
|
|
LoadInst *LI = nullptr;
|
|
Instruction *ExtFedByLoad;
|
|
|
|
// Try to promote a chain of computation if it allows to form an extended
|
|
// load.
|
|
if (canFormExtLd(SpeculativelyMovedExts, LI, ExtFedByLoad, HasPromoted)) {
|
|
assert(LI && ExtFedByLoad && "Expect a valid load and extension");
|
|
TPT.commit();
|
|
// Move the extend into the same block as the load
|
|
ExtFedByLoad->moveAfter(LI);
|
|
// CGP does not check if the zext would be speculatively executed when moved
|
|
// to the same basic block as the load. Preserving its original location
|
|
// would pessimize the debugging experience, as well as negatively impact
|
|
// the quality of sample pgo. We don't want to use "line 0" as that has a
|
|
// size cost in the line-table section and logically the zext can be seen as
|
|
// part of the load. Therefore we conservatively reuse the same debug
|
|
// location for the load and the zext.
|
|
ExtFedByLoad->setDebugLoc(LI->getDebugLoc());
|
|
++NumExtsMoved;
|
|
Inst = ExtFedByLoad;
|
|
return true;
|
|
}
|
|
|
|
// Continue promoting SExts if known as considerable depending on targets.
|
|
if (ATPConsiderable &&
|
|
performAddressTypePromotion(Inst, AllowPromotionWithoutCommonHeader,
|
|
HasPromoted, TPT, SpeculativelyMovedExts))
|
|
return true;
|
|
|
|
TPT.rollback(LastKnownGood);
|
|
return false;
|
|
}
|
|
|
|
// Perform address type promotion if doing so is profitable.
|
|
// If AllowPromotionWithoutCommonHeader == false, we should find other sext
|
|
// instructions that sign extended the same initial value. However, if
|
|
// AllowPromotionWithoutCommonHeader == true, we expect promoting the
|
|
// extension is just profitable.
|
|
bool CodeGenPrepare::performAddressTypePromotion(
|
|
Instruction *&Inst, bool AllowPromotionWithoutCommonHeader,
|
|
bool HasPromoted, TypePromotionTransaction &TPT,
|
|
SmallVectorImpl<Instruction *> &SpeculativelyMovedExts) {
|
|
bool Promoted = false;
|
|
SmallPtrSet<Instruction *, 1> UnhandledExts;
|
|
bool AllSeenFirst = true;
|
|
for (auto I : SpeculativelyMovedExts) {
|
|
Value *HeadOfChain = I->getOperand(0);
|
|
DenseMap<Value *, Instruction *>::iterator AlreadySeen =
|
|
SeenChainsForSExt.find(HeadOfChain);
|
|
// If there is an unhandled SExt which has the same header, try to promote
|
|
// it as well.
|
|
if (AlreadySeen != SeenChainsForSExt.end()) {
|
|
if (AlreadySeen->second != nullptr)
|
|
UnhandledExts.insert(AlreadySeen->second);
|
|
AllSeenFirst = false;
|
|
}
|
|
}
|
|
|
|
if (!AllSeenFirst || (AllowPromotionWithoutCommonHeader &&
|
|
SpeculativelyMovedExts.size() == 1)) {
|
|
TPT.commit();
|
|
if (HasPromoted)
|
|
Promoted = true;
|
|
for (auto I : SpeculativelyMovedExts) {
|
|
Value *HeadOfChain = I->getOperand(0);
|
|
SeenChainsForSExt[HeadOfChain] = nullptr;
|
|
ValToSExtendedUses[HeadOfChain].push_back(I);
|
|
}
|
|
// Update Inst as promotion happen.
|
|
Inst = SpeculativelyMovedExts.pop_back_val();
|
|
} else {
|
|
// This is the first chain visited from the header, keep the current chain
|
|
// as unhandled. Defer to promote this until we encounter another SExt
|
|
// chain derived from the same header.
|
|
for (auto I : SpeculativelyMovedExts) {
|
|
Value *HeadOfChain = I->getOperand(0);
|
|
SeenChainsForSExt[HeadOfChain] = Inst;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
if (!AllSeenFirst && !UnhandledExts.empty())
|
|
for (auto VisitedSExt : UnhandledExts) {
|
|
if (RemovedInsts.count(VisitedSExt))
|
|
continue;
|
|
TypePromotionTransaction TPT(RemovedInsts);
|
|
SmallVector<Instruction *, 1> Exts;
|
|
SmallVector<Instruction *, 2> Chains;
|
|
Exts.push_back(VisitedSExt);
|
|
bool HasPromoted = tryToPromoteExts(TPT, Exts, Chains);
|
|
TPT.commit();
|
|
if (HasPromoted)
|
|
Promoted = true;
|
|
for (auto I : Chains) {
|
|
Value *HeadOfChain = I->getOperand(0);
|
|
// Mark this as handled.
|
|
SeenChainsForSExt[HeadOfChain] = nullptr;
|
|
ValToSExtendedUses[HeadOfChain].push_back(I);
|
|
}
|
|
}
|
|
return Promoted;
|
|
}
|
|
|
|
bool CodeGenPrepare::optimizeExtUses(Instruction *I) {
|
|
BasicBlock *DefBB = I->getParent();
|
|
|
|
// If the result of a {s|z}ext and its source are both live out, rewrite all
|
|
// other uses of the source with result of extension.
|
|
Value *Src = I->getOperand(0);
|
|
if (Src->hasOneUse())
|
|
return false;
|
|
|
|
// Only do this xform if truncating is free.
|
|
if (TLI && !TLI->isTruncateFree(I->getType(), Src->getType()))
|
|
return false;
|
|
|
|
// Only safe to perform the optimization if the source is also defined in
|
|
// this block.
|
|
if (!isa<Instruction>(Src) || DefBB != cast<Instruction>(Src)->getParent())
|
|
return false;
|
|
|
|
bool DefIsLiveOut = false;
|
|
for (User *U : I->users()) {
|
|
Instruction *UI = cast<Instruction>(U);
|
|
|
|
// Figure out which BB this ext is used in.
|
|
BasicBlock *UserBB = UI->getParent();
|
|
if (UserBB == DefBB) continue;
|
|
DefIsLiveOut = true;
|
|
break;
|
|
}
|
|
if (!DefIsLiveOut)
|
|
return false;
|
|
|
|
// Make sure none of the uses are PHI nodes.
|
|
for (User *U : Src->users()) {
|
|
Instruction *UI = cast<Instruction>(U);
|
|
BasicBlock *UserBB = UI->getParent();
|
|
if (UserBB == DefBB) continue;
|
|
// Be conservative. We don't want this xform to end up introducing
|
|
// reloads just before load / store instructions.
|
|
if (isa<PHINode>(UI) || isa<LoadInst>(UI) || isa<StoreInst>(UI))
|
|
return false;
|
|
}
|
|
|
|
// InsertedTruncs - Only insert one trunc in each block once.
|
|
DenseMap<BasicBlock*, Instruction*> InsertedTruncs;
|
|
|
|
bool MadeChange = false;
|
|
for (Use &U : Src->uses()) {
|
|
Instruction *User = cast<Instruction>(U.getUser());
|
|
|
|
// Figure out which BB this ext is used in.
|
|
BasicBlock *UserBB = User->getParent();
|
|
if (UserBB == DefBB) continue;
|
|
|
|
// Both src and def are live in this block. Rewrite the use.
|
|
Instruction *&InsertedTrunc = InsertedTruncs[UserBB];
|
|
|
|
if (!InsertedTrunc) {
|
|
BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
|
|
assert(InsertPt != UserBB->end());
|
|
InsertedTrunc = new TruncInst(I, Src->getType(), "", &*InsertPt);
|
|
InsertedInsts.insert(InsertedTrunc);
|
|
}
|
|
|
|
// Replace a use of the {s|z}ext source with a use of the result.
|
|
U = InsertedTrunc;
|
|
++NumExtUses;
|
|
MadeChange = true;
|
|
}
|
|
|
|
return MadeChange;
|
|
}
|
|
|
|
// Find loads whose uses only use some of the loaded value's bits. Add an "and"
|
|
// just after the load if the target can fold this into one extload instruction,
|
|
// with the hope of eliminating some of the other later "and" instructions using
|
|
// the loaded value. "and"s that are made trivially redundant by the insertion
|
|
// of the new "and" are removed by this function, while others (e.g. those whose
|
|
// path from the load goes through a phi) are left for isel to potentially
|
|
// remove.
|
|
//
|
|
// For example:
|
|
//
|
|
// b0:
|
|
// x = load i32
|
|
// ...
|
|
// b1:
|
|
// y = and x, 0xff
|
|
// z = use y
|
|
//
|
|
// becomes:
|
|
//
|
|
// b0:
|
|
// x = load i32
|
|
// x' = and x, 0xff
|
|
// ...
|
|
// b1:
|
|
// z = use x'
|
|
//
|
|
// whereas:
|
|
//
|
|
// b0:
|
|
// x1 = load i32
|
|
// ...
|
|
// b1:
|
|
// x2 = load i32
|
|
// ...
|
|
// b2:
|
|
// x = phi x1, x2
|
|
// y = and x, 0xff
|
|
//
|
|
// becomes (after a call to optimizeLoadExt for each load):
|
|
//
|
|
// b0:
|
|
// x1 = load i32
|
|
// x1' = and x1, 0xff
|
|
// ...
|
|
// b1:
|
|
// x2 = load i32
|
|
// x2' = and x2, 0xff
|
|
// ...
|
|
// b2:
|
|
// x = phi x1', x2'
|
|
// y = and x, 0xff
|
|
bool CodeGenPrepare::optimizeLoadExt(LoadInst *Load) {
|
|
if (!Load->isSimple() || !Load->getType()->isIntOrPtrTy())
|
|
return false;
|
|
|
|
// Skip loads we've already transformed.
|
|
if (Load->hasOneUse() &&
|
|
InsertedInsts.count(cast<Instruction>(*Load->user_begin())))
|
|
return false;
|
|
|
|
// Look at all uses of Load, looking through phis, to determine how many bits
|
|
// of the loaded value are needed.
|
|
SmallVector<Instruction *, 8> WorkList;
|
|
SmallPtrSet<Instruction *, 16> Visited;
|
|
SmallVector<Instruction *, 8> AndsToMaybeRemove;
|
|
for (auto *U : Load->users())
|
|
WorkList.push_back(cast<Instruction>(U));
|
|
|
|
EVT LoadResultVT = TLI->getValueType(*DL, Load->getType());
|
|
unsigned BitWidth = LoadResultVT.getSizeInBits();
|
|
APInt DemandBits(BitWidth, 0);
|
|
APInt WidestAndBits(BitWidth, 0);
|
|
|
|
while (!WorkList.empty()) {
|
|
Instruction *I = WorkList.back();
|
|
WorkList.pop_back();
|
|
|
|
// Break use-def graph loops.
|
|
if (!Visited.insert(I).second)
|
|
continue;
|
|
|
|
// For a PHI node, push all of its users.
|
|
if (auto *Phi = dyn_cast<PHINode>(I)) {
|
|
for (auto *U : Phi->users())
|
|
WorkList.push_back(cast<Instruction>(U));
|
|
continue;
|
|
}
|
|
|
|
switch (I->getOpcode()) {
|
|
case Instruction::And: {
|
|
auto *AndC = dyn_cast<ConstantInt>(I->getOperand(1));
|
|
if (!AndC)
|
|
return false;
|
|
APInt AndBits = AndC->getValue();
|
|
DemandBits |= AndBits;
|
|
// Keep track of the widest and mask we see.
|
|
if (AndBits.ugt(WidestAndBits))
|
|
WidestAndBits = AndBits;
|
|
if (AndBits == WidestAndBits && I->getOperand(0) == Load)
|
|
AndsToMaybeRemove.push_back(I);
|
|
break;
|
|
}
|
|
|
|
case Instruction::Shl: {
|
|
auto *ShlC = dyn_cast<ConstantInt>(I->getOperand(1));
|
|
if (!ShlC)
|
|
return false;
|
|
uint64_t ShiftAmt = ShlC->getLimitedValue(BitWidth - 1);
|
|
DemandBits.setLowBits(BitWidth - ShiftAmt);
|
|
break;
|
|
}
|
|
|
|
case Instruction::Trunc: {
|
|
EVT TruncVT = TLI->getValueType(*DL, I->getType());
|
|
unsigned TruncBitWidth = TruncVT.getSizeInBits();
|
|
DemandBits.setLowBits(TruncBitWidth);
|
|
break;
|
|
}
|
|
|
|
default:
|
|
return false;
|
|
}
|
|
}
|
|
|
|
uint32_t ActiveBits = DemandBits.getActiveBits();
|
|
// Avoid hoisting (and (load x) 1) since it is unlikely to be folded by the
|
|
// target even if isLoadExtLegal says an i1 EXTLOAD is valid. For example,
|
|
// for the AArch64 target isLoadExtLegal(ZEXTLOAD, i32, i1) returns true, but
|
|
// (and (load x) 1) is not matched as a single instruction, rather as a LDR
|
|
// followed by an AND.
|
|
// TODO: Look into removing this restriction by fixing backends to either
|
|
// return false for isLoadExtLegal for i1 or have them select this pattern to
|
|
// a single instruction.
|
|
//
|
|
// Also avoid hoisting if we didn't see any ands with the exact DemandBits
|
|
// mask, since these are the only ands that will be removed by isel.
|
|
if (ActiveBits <= 1 || !DemandBits.isMask(ActiveBits) ||
|
|
WidestAndBits != DemandBits)
|
|
return false;
|
|
|
|
LLVMContext &Ctx = Load->getType()->getContext();
|
|
Type *TruncTy = Type::getIntNTy(Ctx, ActiveBits);
|
|
EVT TruncVT = TLI->getValueType(*DL, TruncTy);
|
|
|
|
// Reject cases that won't be matched as extloads.
|
|
if (!LoadResultVT.bitsGT(TruncVT) || !TruncVT.isRound() ||
|
|
!TLI->isLoadExtLegal(ISD::ZEXTLOAD, LoadResultVT, TruncVT))
|
|
return false;
|
|
|
|
IRBuilder<> Builder(Load->getNextNode());
|
|
auto *NewAnd = dyn_cast<Instruction>(
|
|
Builder.CreateAnd(Load, ConstantInt::get(Ctx, DemandBits)));
|
|
// Mark this instruction as "inserted by CGP", so that other
|
|
// optimizations don't touch it.
|
|
InsertedInsts.insert(NewAnd);
|
|
|
|
// Replace all uses of load with new and (except for the use of load in the
|
|
// new and itself).
|
|
Load->replaceAllUsesWith(NewAnd);
|
|
NewAnd->setOperand(0, Load);
|
|
|
|
// Remove any and instructions that are now redundant.
|
|
for (auto *And : AndsToMaybeRemove)
|
|
// Check that the and mask is the same as the one we decided to put on the
|
|
// new and.
|
|
if (cast<ConstantInt>(And->getOperand(1))->getValue() == DemandBits) {
|
|
And->replaceAllUsesWith(NewAnd);
|
|
if (&*CurInstIterator == And)
|
|
CurInstIterator = std::next(And->getIterator());
|
|
And->eraseFromParent();
|
|
++NumAndUses;
|
|
}
|
|
|
|
++NumAndsAdded;
|
|
return true;
|
|
}
|
|
|
|
/// Check if V (an operand of a select instruction) is an expensive instruction
|
|
/// that is only used once.
|
|
static bool sinkSelectOperand(const TargetTransformInfo *TTI, Value *V) {
|
|
auto *I = dyn_cast<Instruction>(V);
|
|
// If it's safe to speculatively execute, then it should not have side
|
|
// effects; therefore, it's safe to sink and possibly *not* execute.
|
|
return I && I->hasOneUse() && isSafeToSpeculativelyExecute(I) &&
|
|
TTI->getUserCost(I) >= TargetTransformInfo::TCC_Expensive;
|
|
}
|
|
|
|
/// Returns true if a SelectInst should be turned into an explicit branch.
|
|
static bool isFormingBranchFromSelectProfitable(const TargetTransformInfo *TTI,
|
|
const TargetLowering *TLI,
|
|
SelectInst *SI) {
|
|
// If even a predictable select is cheap, then a branch can't be cheaper.
|
|
if (!TLI->isPredictableSelectExpensive())
|
|
return false;
|
|
|
|
// FIXME: This should use the same heuristics as IfConversion to determine
|
|
// whether a select is better represented as a branch.
|
|
|
|
// If metadata tells us that the select condition is obviously predictable,
|
|
// then we want to replace the select with a branch.
|
|
uint64_t TrueWeight, FalseWeight;
|
|
if (SI->extractProfMetadata(TrueWeight, FalseWeight)) {
|
|
uint64_t Max = std::max(TrueWeight, FalseWeight);
|
|
uint64_t Sum = TrueWeight + FalseWeight;
|
|
if (Sum != 0) {
|
|
auto Probability = BranchProbability::getBranchProbability(Max, Sum);
|
|
if (Probability > TLI->getPredictableBranchThreshold())
|
|
return true;
|
|
}
|
|
}
|
|
|
|
CmpInst *Cmp = dyn_cast<CmpInst>(SI->getCondition());
|
|
|
|
// If a branch is predictable, an out-of-order CPU can avoid blocking on its
|
|
// comparison condition. If the compare has more than one use, there's
|
|
// probably another cmov or setcc around, so it's not worth emitting a branch.
|
|
if (!Cmp || !Cmp->hasOneUse())
|
|
return false;
|
|
|
|
// If either operand of the select is expensive and only needed on one side
|
|
// of the select, we should form a branch.
|
|
if (sinkSelectOperand(TTI, SI->getTrueValue()) ||
|
|
sinkSelectOperand(TTI, SI->getFalseValue()))
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
/// If \p isTrue is true, return the true value of \p SI, otherwise return
|
|
/// false value of \p SI. If the true/false value of \p SI is defined by any
|
|
/// select instructions in \p Selects, look through the defining select
|
|
/// instruction until the true/false value is not defined in \p Selects.
|
|
static Value *getTrueOrFalseValue(
|
|
SelectInst *SI, bool isTrue,
|
|
const SmallPtrSet<const Instruction *, 2> &Selects) {
|
|
Value *V;
|
|
|
|
for (SelectInst *DefSI = SI; DefSI != nullptr && Selects.count(DefSI);
|
|
DefSI = dyn_cast<SelectInst>(V)) {
|
|
assert(DefSI->getCondition() == SI->getCondition() &&
|
|
"The condition of DefSI does not match with SI");
|
|
V = (isTrue ? DefSI->getTrueValue() : DefSI->getFalseValue());
|
|
}
|
|
return V;
|
|
}
|
|
|
|
/// If we have a SelectInst that will likely profit from branch prediction,
|
|
/// turn it into a branch.
|
|
bool CodeGenPrepare::optimizeSelectInst(SelectInst *SI) {
|
|
// If branch conversion isn't desirable, exit early.
|
|
if (DisableSelectToBranch || OptSize || !TLI)
|
|
return false;
|
|
|
|
// Find all consecutive select instructions that share the same condition.
|
|
SmallVector<SelectInst *, 2> ASI;
|
|
ASI.push_back(SI);
|
|
for (BasicBlock::iterator It = ++BasicBlock::iterator(SI);
|
|
It != SI->getParent()->end(); ++It) {
|
|
SelectInst *I = dyn_cast<SelectInst>(&*It);
|
|
if (I && SI->getCondition() == I->getCondition()) {
|
|
ASI.push_back(I);
|
|
} else {
|
|
break;
|
|
}
|
|
}
|
|
|
|
SelectInst *LastSI = ASI.back();
|
|
// Increment the current iterator to skip all the rest of select instructions
|
|
// because they will be either "not lowered" or "all lowered" to branch.
|
|
CurInstIterator = std::next(LastSI->getIterator());
|
|
|
|
bool VectorCond = !SI->getCondition()->getType()->isIntegerTy(1);
|
|
|
|
// Can we convert the 'select' to CF ?
|
|
if (VectorCond || SI->getMetadata(LLVMContext::MD_unpredictable))
|
|
return false;
|
|
|
|
TargetLowering::SelectSupportKind SelectKind;
|
|
if (VectorCond)
|
|
SelectKind = TargetLowering::VectorMaskSelect;
|
|
else if (SI->getType()->isVectorTy())
|
|
SelectKind = TargetLowering::ScalarCondVectorVal;
|
|
else
|
|
SelectKind = TargetLowering::ScalarValSelect;
|
|
|
|
if (TLI->isSelectSupported(SelectKind) &&
|
|
!isFormingBranchFromSelectProfitable(TTI, TLI, SI))
|
|
return false;
|
|
|
|
ModifiedDT = true;
|
|
|
|
// Transform a sequence like this:
|
|
// start:
|
|
// %cmp = cmp uge i32 %a, %b
|
|
// %sel = select i1 %cmp, i32 %c, i32 %d
|
|
//
|
|
// Into:
|
|
// start:
|
|
// %cmp = cmp uge i32 %a, %b
|
|
// br i1 %cmp, label %select.true, label %select.false
|
|
// select.true:
|
|
// br label %select.end
|
|
// select.false:
|
|
// br label %select.end
|
|
// select.end:
|
|
// %sel = phi i32 [ %c, %select.true ], [ %d, %select.false ]
|
|
//
|
|
// In addition, we may sink instructions that produce %c or %d from
|
|
// the entry block into the destination(s) of the new branch.
|
|
// If the true or false blocks do not contain a sunken instruction, that
|
|
// block and its branch may be optimized away. In that case, one side of the
|
|
// first branch will point directly to select.end, and the corresponding PHI
|
|
// predecessor block will be the start block.
|
|
|
|
// First, we split the block containing the select into 2 blocks.
|
|
BasicBlock *StartBlock = SI->getParent();
|
|
BasicBlock::iterator SplitPt = ++(BasicBlock::iterator(LastSI));
|
|
BasicBlock *EndBlock = StartBlock->splitBasicBlock(SplitPt, "select.end");
|
|
|
|
// Delete the unconditional branch that was just created by the split.
|
|
StartBlock->getTerminator()->eraseFromParent();
|
|
|
|
// These are the new basic blocks for the conditional branch.
|
|
// At least one will become an actual new basic block.
|
|
BasicBlock *TrueBlock = nullptr;
|
|
BasicBlock *FalseBlock = nullptr;
|
|
BranchInst *TrueBranch = nullptr;
|
|
BranchInst *FalseBranch = nullptr;
|
|
|
|
// Sink expensive instructions into the conditional blocks to avoid executing
|
|
// them speculatively.
|
|
for (SelectInst *SI : ASI) {
|
|
if (sinkSelectOperand(TTI, SI->getTrueValue())) {
|
|
if (TrueBlock == nullptr) {
|
|
TrueBlock = BasicBlock::Create(SI->getContext(), "select.true.sink",
|
|
EndBlock->getParent(), EndBlock);
|
|
TrueBranch = BranchInst::Create(EndBlock, TrueBlock);
|
|
TrueBranch->setDebugLoc(SI->getDebugLoc());
|
|
}
|
|
auto *TrueInst = cast<Instruction>(SI->getTrueValue());
|
|
TrueInst->moveBefore(TrueBranch);
|
|
}
|
|
if (sinkSelectOperand(TTI, SI->getFalseValue())) {
|
|
if (FalseBlock == nullptr) {
|
|
FalseBlock = BasicBlock::Create(SI->getContext(), "select.false.sink",
|
|
EndBlock->getParent(), EndBlock);
|
|
FalseBranch = BranchInst::Create(EndBlock, FalseBlock);
|
|
FalseBranch->setDebugLoc(SI->getDebugLoc());
|
|
}
|
|
auto *FalseInst = cast<Instruction>(SI->getFalseValue());
|
|
FalseInst->moveBefore(FalseBranch);
|
|
}
|
|
}
|
|
|
|
// If there was nothing to sink, then arbitrarily choose the 'false' side
|
|
// for a new input value to the PHI.
|
|
if (TrueBlock == FalseBlock) {
|
|
assert(TrueBlock == nullptr &&
|
|
"Unexpected basic block transform while optimizing select");
|
|
|
|
FalseBlock = BasicBlock::Create(SI->getContext(), "select.false",
|
|
EndBlock->getParent(), EndBlock);
|
|
auto *FalseBranch = BranchInst::Create(EndBlock, FalseBlock);
|
|
FalseBranch->setDebugLoc(SI->getDebugLoc());
|
|
}
|
|
|
|
// Insert the real conditional branch based on the original condition.
|
|
// If we did not create a new block for one of the 'true' or 'false' paths
|
|
// of the condition, it means that side of the branch goes to the end block
|
|
// directly and the path originates from the start block from the point of
|
|
// view of the new PHI.
|
|
BasicBlock *TT, *FT;
|
|
if (TrueBlock == nullptr) {
|
|
TT = EndBlock;
|
|
FT = FalseBlock;
|
|
TrueBlock = StartBlock;
|
|
} else if (FalseBlock == nullptr) {
|
|
TT = TrueBlock;
|
|
FT = EndBlock;
|
|
FalseBlock = StartBlock;
|
|
} else {
|
|
TT = TrueBlock;
|
|
FT = FalseBlock;
|
|
}
|
|
IRBuilder<>(SI).CreateCondBr(SI->getCondition(), TT, FT, SI);
|
|
|
|
SmallPtrSet<const Instruction *, 2> INS;
|
|
INS.insert(ASI.begin(), ASI.end());
|
|
// Use reverse iterator because later select may use the value of the
|
|
// earlier select, and we need to propagate value through earlier select
|
|
// to get the PHI operand.
|
|
for (auto It = ASI.rbegin(); It != ASI.rend(); ++It) {
|
|
SelectInst *SI = *It;
|
|
// The select itself is replaced with a PHI Node.
|
|
PHINode *PN = PHINode::Create(SI->getType(), 2, "", &EndBlock->front());
|
|
PN->takeName(SI);
|
|
PN->addIncoming(getTrueOrFalseValue(SI, true, INS), TrueBlock);
|
|
PN->addIncoming(getTrueOrFalseValue(SI, false, INS), FalseBlock);
|
|
PN->setDebugLoc(SI->getDebugLoc());
|
|
|
|
SI->replaceAllUsesWith(PN);
|
|
SI->eraseFromParent();
|
|
INS.erase(SI);
|
|
++NumSelectsExpanded;
|
|
}
|
|
|
|
// Instruct OptimizeBlock to skip to the next block.
|
|
CurInstIterator = StartBlock->end();
|
|
return true;
|
|
}
|
|
|
|
static bool isBroadcastShuffle(ShuffleVectorInst *SVI) {
|
|
SmallVector<int, 16> Mask(SVI->getShuffleMask());
|
|
int SplatElem = -1;
|
|
for (unsigned i = 0; i < Mask.size(); ++i) {
|
|
if (SplatElem != -1 && Mask[i] != -1 && Mask[i] != SplatElem)
|
|
return false;
|
|
SplatElem = Mask[i];
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
/// Some targets have expensive vector shifts if the lanes aren't all the same
|
|
/// (e.g. x86 only introduced "vpsllvd" and friends with AVX2). In these cases
|
|
/// it's often worth sinking a shufflevector splat down to its use so that
|
|
/// codegen can spot all lanes are identical.
|
|
bool CodeGenPrepare::optimizeShuffleVectorInst(ShuffleVectorInst *SVI) {
|
|
BasicBlock *DefBB = SVI->getParent();
|
|
|
|
// Only do this xform if variable vector shifts are particularly expensive.
|
|
if (!TLI || !TLI->isVectorShiftByScalarCheap(SVI->getType()))
|
|
return false;
|
|
|
|
// We only expect better codegen by sinking a shuffle if we can recognise a
|
|
// constant splat.
|
|
if (!isBroadcastShuffle(SVI))
|
|
return false;
|
|
|
|
// InsertedShuffles - Only insert a shuffle in each block once.
|
|
DenseMap<BasicBlock*, Instruction*> InsertedShuffles;
|
|
|
|
bool MadeChange = false;
|
|
for (User *U : SVI->users()) {
|
|
Instruction *UI = cast<Instruction>(U);
|
|
|
|
// Figure out which BB this ext is used in.
|
|
BasicBlock *UserBB = UI->getParent();
|
|
if (UserBB == DefBB) continue;
|
|
|
|
// For now only apply this when the splat is used by a shift instruction.
|
|
if (!UI->isShift()) continue;
|
|
|
|
// Everything checks out, sink the shuffle if the user's block doesn't
|
|
// already have a copy.
|
|
Instruction *&InsertedShuffle = InsertedShuffles[UserBB];
|
|
|
|
if (!InsertedShuffle) {
|
|
BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
|
|
assert(InsertPt != UserBB->end());
|
|
InsertedShuffle =
|
|
new ShuffleVectorInst(SVI->getOperand(0), SVI->getOperand(1),
|
|
SVI->getOperand(2), "", &*InsertPt);
|
|
}
|
|
|
|
UI->replaceUsesOfWith(SVI, InsertedShuffle);
|
|
MadeChange = true;
|
|
}
|
|
|
|
// If we removed all uses, nuke the shuffle.
|
|
if (SVI->use_empty()) {
|
|
SVI->eraseFromParent();
|
|
MadeChange = true;
|
|
}
|
|
|
|
return MadeChange;
|
|
}
|
|
|
|
bool CodeGenPrepare::optimizeSwitchInst(SwitchInst *SI) {
|
|
if (!TLI || !DL)
|
|
return false;
|
|
|
|
Value *Cond = SI->getCondition();
|
|
Type *OldType = Cond->getType();
|
|
LLVMContext &Context = Cond->getContext();
|
|
MVT RegType = TLI->getRegisterType(Context, TLI->getValueType(*DL, OldType));
|
|
unsigned RegWidth = RegType.getSizeInBits();
|
|
|
|
if (RegWidth <= cast<IntegerType>(OldType)->getBitWidth())
|
|
return false;
|
|
|
|
// If the register width is greater than the type width, expand the condition
|
|
// of the switch instruction and each case constant to the width of the
|
|
// register. By widening the type of the switch condition, subsequent
|
|
// comparisons (for case comparisons) will not need to be extended to the
|
|
// preferred register width, so we will potentially eliminate N-1 extends,
|
|
// where N is the number of cases in the switch.
|
|
auto *NewType = Type::getIntNTy(Context, RegWidth);
|
|
|
|
// Zero-extend the switch condition and case constants unless the switch
|
|
// condition is a function argument that is already being sign-extended.
|
|
// In that case, we can avoid an unnecessary mask/extension by sign-extending
|
|
// everything instead.
|
|
Instruction::CastOps ExtType = Instruction::ZExt;
|
|
if (auto *Arg = dyn_cast<Argument>(Cond))
|
|
if (Arg->hasSExtAttr())
|
|
ExtType = Instruction::SExt;
|
|
|
|
auto *ExtInst = CastInst::Create(ExtType, Cond, NewType);
|
|
ExtInst->insertBefore(SI);
|
|
ExtInst->setDebugLoc(SI->getDebugLoc());
|
|
SI->setCondition(ExtInst);
|
|
for (auto Case : SI->cases()) {
|
|
APInt NarrowConst = Case.getCaseValue()->getValue();
|
|
APInt WideConst = (ExtType == Instruction::ZExt) ?
|
|
NarrowConst.zext(RegWidth) : NarrowConst.sext(RegWidth);
|
|
Case.setValue(ConstantInt::get(Context, WideConst));
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
|
|
namespace {
|
|
|
|
/// Helper class to promote a scalar operation to a vector one.
|
|
/// This class is used to move downward extractelement transition.
|
|
/// E.g.,
|
|
/// a = vector_op <2 x i32>
|
|
/// b = extractelement <2 x i32> a, i32 0
|
|
/// c = scalar_op b
|
|
/// store c
|
|
///
|
|
/// =>
|
|
/// a = vector_op <2 x i32>
|
|
/// c = vector_op a (equivalent to scalar_op on the related lane)
|
|
/// * d = extractelement <2 x i32> c, i32 0
|
|
/// * store d
|
|
/// Assuming both extractelement and store can be combine, we get rid of the
|
|
/// transition.
|
|
class VectorPromoteHelper {
|
|
/// DataLayout associated with the current module.
|
|
const DataLayout &DL;
|
|
|
|
/// Used to perform some checks on the legality of vector operations.
|
|
const TargetLowering &TLI;
|
|
|
|
/// Used to estimated the cost of the promoted chain.
|
|
const TargetTransformInfo &TTI;
|
|
|
|
/// The transition being moved downwards.
|
|
Instruction *Transition;
|
|
|
|
/// The sequence of instructions to be promoted.
|
|
SmallVector<Instruction *, 4> InstsToBePromoted;
|
|
|
|
/// Cost of combining a store and an extract.
|
|
unsigned StoreExtractCombineCost;
|
|
|
|
/// Instruction that will be combined with the transition.
|
|
Instruction *CombineInst = nullptr;
|
|
|
|
/// The instruction that represents the current end of the transition.
|
|
/// Since we are faking the promotion until we reach the end of the chain
|
|
/// of computation, we need a way to get the current end of the transition.
|
|
Instruction *getEndOfTransition() const {
|
|
if (InstsToBePromoted.empty())
|
|
return Transition;
|
|
return InstsToBePromoted.back();
|
|
}
|
|
|
|
/// Return the index of the original value in the transition.
|
|
/// E.g., for "extractelement <2 x i32> c, i32 1" the original value,
|
|
/// c, is at index 0.
|
|
unsigned getTransitionOriginalValueIdx() const {
|
|
assert(isa<ExtractElementInst>(Transition) &&
|
|
"Other kind of transitions are not supported yet");
|
|
return 0;
|
|
}
|
|
|
|
/// Return the index of the index in the transition.
|
|
/// E.g., for "extractelement <2 x i32> c, i32 0" the index
|
|
/// is at index 1.
|
|
unsigned getTransitionIdx() const {
|
|
assert(isa<ExtractElementInst>(Transition) &&
|
|
"Other kind of transitions are not supported yet");
|
|
return 1;
|
|
}
|
|
|
|
/// Get the type of the transition.
|
|
/// This is the type of the original value.
|
|
/// E.g., for "extractelement <2 x i32> c, i32 1" the type of the
|
|
/// transition is <2 x i32>.
|
|
Type *getTransitionType() const {
|
|
return Transition->getOperand(getTransitionOriginalValueIdx())->getType();
|
|
}
|
|
|
|
/// Promote \p ToBePromoted by moving \p Def downward through.
|
|
/// I.e., we have the following sequence:
|
|
/// Def = Transition <ty1> a to <ty2>
|
|
/// b = ToBePromoted <ty2> Def, ...
|
|
/// =>
|
|
/// b = ToBePromoted <ty1> a, ...
|
|
/// Def = Transition <ty1> ToBePromoted to <ty2>
|
|
void promoteImpl(Instruction *ToBePromoted);
|
|
|
|
/// Check whether or not it is profitable to promote all the
|
|
/// instructions enqueued to be promoted.
|
|
bool isProfitableToPromote() {
|
|
Value *ValIdx = Transition->getOperand(getTransitionOriginalValueIdx());
|
|
unsigned Index = isa<ConstantInt>(ValIdx)
|
|
? cast<ConstantInt>(ValIdx)->getZExtValue()
|
|
: -1;
|
|
Type *PromotedType = getTransitionType();
|
|
|
|
StoreInst *ST = cast<StoreInst>(CombineInst);
|
|
unsigned AS = ST->getPointerAddressSpace();
|
|
unsigned Align = ST->getAlignment();
|
|
// Check if this store is supported.
|
|
if (!TLI.allowsMisalignedMemoryAccesses(
|
|
TLI.getValueType(DL, ST->getValueOperand()->getType()), AS,
|
|
Align)) {
|
|
// If this is not supported, there is no way we can combine
|
|
// the extract with the store.
|
|
return false;
|
|
}
|
|
|
|
// The scalar chain of computation has to pay for the transition
|
|
// scalar to vector.
|
|
// The vector chain has to account for the combining cost.
|
|
uint64_t ScalarCost =
|
|
TTI.getVectorInstrCost(Transition->getOpcode(), PromotedType, Index);
|
|
uint64_t VectorCost = StoreExtractCombineCost;
|
|
for (const auto &Inst : InstsToBePromoted) {
|
|
// Compute the cost.
|
|
// By construction, all instructions being promoted are arithmetic ones.
|
|
// Moreover, one argument is a constant that can be viewed as a splat
|
|
// constant.
|
|
Value *Arg0 = Inst->getOperand(0);
|
|
bool IsArg0Constant = isa<UndefValue>(Arg0) || isa<ConstantInt>(Arg0) ||
|
|
isa<ConstantFP>(Arg0);
|
|
TargetTransformInfo::OperandValueKind Arg0OVK =
|
|
IsArg0Constant ? TargetTransformInfo::OK_UniformConstantValue
|
|
: TargetTransformInfo::OK_AnyValue;
|
|
TargetTransformInfo::OperandValueKind Arg1OVK =
|
|
!IsArg0Constant ? TargetTransformInfo::OK_UniformConstantValue
|
|
: TargetTransformInfo::OK_AnyValue;
|
|
ScalarCost += TTI.getArithmeticInstrCost(
|
|
Inst->getOpcode(), Inst->getType(), Arg0OVK, Arg1OVK);
|
|
VectorCost += TTI.getArithmeticInstrCost(Inst->getOpcode(), PromotedType,
|
|
Arg0OVK, Arg1OVK);
|
|
}
|
|
LLVM_DEBUG(
|
|
dbgs() << "Estimated cost of computation to be promoted:\nScalar: "
|
|
<< ScalarCost << "\nVector: " << VectorCost << '\n');
|
|
return ScalarCost > VectorCost;
|
|
}
|
|
|
|
/// Generate a constant vector with \p Val with the same
|
|
/// number of elements as the transition.
|
|
/// \p UseSplat defines whether or not \p Val should be replicated
|
|
/// across the whole vector.
|
|
/// In other words, if UseSplat == true, we generate <Val, Val, ..., Val>,
|
|
/// otherwise we generate a vector with as many undef as possible:
|
|
/// <undef, ..., undef, Val, undef, ..., undef> where \p Val is only
|
|
/// used at the index of the extract.
|
|
Value *getConstantVector(Constant *Val, bool UseSplat) const {
|
|
unsigned ExtractIdx = std::numeric_limits<unsigned>::max();
|
|
if (!UseSplat) {
|
|
// If we cannot determine where the constant must be, we have to
|
|
// use a splat constant.
|
|
Value *ValExtractIdx = Transition->getOperand(getTransitionIdx());
|
|
if (ConstantInt *CstVal = dyn_cast<ConstantInt>(ValExtractIdx))
|
|
ExtractIdx = CstVal->getSExtValue();
|
|
else
|
|
UseSplat = true;
|
|
}
|
|
|
|
unsigned End = getTransitionType()->getVectorNumElements();
|
|
if (UseSplat)
|
|
return ConstantVector::getSplat(End, Val);
|
|
|
|
SmallVector<Constant *, 4> ConstVec;
|
|
UndefValue *UndefVal = UndefValue::get(Val->getType());
|
|
for (unsigned Idx = 0; Idx != End; ++Idx) {
|
|
if (Idx == ExtractIdx)
|
|
ConstVec.push_back(Val);
|
|
else
|
|
ConstVec.push_back(UndefVal);
|
|
}
|
|
return ConstantVector::get(ConstVec);
|
|
}
|
|
|
|
/// Check if promoting to a vector type an operand at \p OperandIdx
|
|
/// in \p Use can trigger undefined behavior.
|
|
static bool canCauseUndefinedBehavior(const Instruction *Use,
|
|
unsigned OperandIdx) {
|
|
// This is not safe to introduce undef when the operand is on
|
|
// the right hand side of a division-like instruction.
|
|
if (OperandIdx != 1)
|
|
return false;
|
|
switch (Use->getOpcode()) {
|
|
default:
|
|
return false;
|
|
case Instruction::SDiv:
|
|
case Instruction::UDiv:
|
|
case Instruction::SRem:
|
|
case Instruction::URem:
|
|
return true;
|
|
case Instruction::FDiv:
|
|
case Instruction::FRem:
|
|
return !Use->hasNoNaNs();
|
|
}
|
|
llvm_unreachable(nullptr);
|
|
}
|
|
|
|
public:
|
|
VectorPromoteHelper(const DataLayout &DL, const TargetLowering &TLI,
|
|
const TargetTransformInfo &TTI, Instruction *Transition,
|
|
unsigned CombineCost)
|
|
: DL(DL), TLI(TLI), TTI(TTI), Transition(Transition),
|
|
StoreExtractCombineCost(CombineCost) {
|
|
assert(Transition && "Do not know how to promote null");
|
|
}
|
|
|
|
/// Check if we can promote \p ToBePromoted to \p Type.
|
|
bool canPromote(const Instruction *ToBePromoted) const {
|
|
// We could support CastInst too.
|
|
return isa<BinaryOperator>(ToBePromoted);
|
|
}
|
|
|
|
/// Check if it is profitable to promote \p ToBePromoted
|
|
/// by moving downward the transition through.
|
|
bool shouldPromote(const Instruction *ToBePromoted) const {
|
|
// Promote only if all the operands can be statically expanded.
|
|
// Indeed, we do not want to introduce any new kind of transitions.
|
|
for (const Use &U : ToBePromoted->operands()) {
|
|
const Value *Val = U.get();
|
|
if (Val == getEndOfTransition()) {
|
|
// If the use is a division and the transition is on the rhs,
|
|
// we cannot promote the operation, otherwise we may create a
|
|
// division by zero.
|
|
if (canCauseUndefinedBehavior(ToBePromoted, U.getOperandNo()))
|
|
return false;
|
|
continue;
|
|
}
|
|
if (!isa<ConstantInt>(Val) && !isa<UndefValue>(Val) &&
|
|
!isa<ConstantFP>(Val))
|
|
return false;
|
|
}
|
|
// Check that the resulting operation is legal.
|
|
int ISDOpcode = TLI.InstructionOpcodeToISD(ToBePromoted->getOpcode());
|
|
if (!ISDOpcode)
|
|
return false;
|
|
return StressStoreExtract ||
|
|
TLI.isOperationLegalOrCustom(
|
|
ISDOpcode, TLI.getValueType(DL, getTransitionType(), true));
|
|
}
|
|
|
|
/// Check whether or not \p Use can be combined
|
|
/// with the transition.
|
|
/// I.e., is it possible to do Use(Transition) => AnotherUse?
|
|
bool canCombine(const Instruction *Use) { return isa<StoreInst>(Use); }
|
|
|
|
/// Record \p ToBePromoted as part of the chain to be promoted.
|
|
void enqueueForPromotion(Instruction *ToBePromoted) {
|
|
InstsToBePromoted.push_back(ToBePromoted);
|
|
}
|
|
|
|
/// Set the instruction that will be combined with the transition.
|
|
void recordCombineInstruction(Instruction *ToBeCombined) {
|
|
assert(canCombine(ToBeCombined) && "Unsupported instruction to combine");
|
|
CombineInst = ToBeCombined;
|
|
}
|
|
|
|
/// Promote all the instructions enqueued for promotion if it is
|
|
/// is profitable.
|
|
/// \return True if the promotion happened, false otherwise.
|
|
bool promote() {
|
|
// Check if there is something to promote.
|
|
// Right now, if we do not have anything to combine with,
|
|
// we assume the promotion is not profitable.
|
|
if (InstsToBePromoted.empty() || !CombineInst)
|
|
return false;
|
|
|
|
// Check cost.
|
|
if (!StressStoreExtract && !isProfitableToPromote())
|
|
return false;
|
|
|
|
// Promote.
|
|
for (auto &ToBePromoted : InstsToBePromoted)
|
|
promoteImpl(ToBePromoted);
|
|
InstsToBePromoted.clear();
|
|
return true;
|
|
}
|
|
};
|
|
|
|
} // end anonymous namespace
|
|
|
|
void VectorPromoteHelper::promoteImpl(Instruction *ToBePromoted) {
|
|
// At this point, we know that all the operands of ToBePromoted but Def
|
|
// can be statically promoted.
|
|
// For Def, we need to use its parameter in ToBePromoted:
|
|
// b = ToBePromoted ty1 a
|
|
// Def = Transition ty1 b to ty2
|
|
// Move the transition down.
|
|
// 1. Replace all uses of the promoted operation by the transition.
|
|
// = ... b => = ... Def.
|
|
assert(ToBePromoted->getType() == Transition->getType() &&
|
|
"The type of the result of the transition does not match "
|
|
"the final type");
|
|
ToBePromoted->replaceAllUsesWith(Transition);
|
|
// 2. Update the type of the uses.
|
|
// b = ToBePromoted ty2 Def => b = ToBePromoted ty1 Def.
|
|
Type *TransitionTy = getTransitionType();
|
|
ToBePromoted->mutateType(TransitionTy);
|
|
// 3. Update all the operands of the promoted operation with promoted
|
|
// operands.
|
|
// b = ToBePromoted ty1 Def => b = ToBePromoted ty1 a.
|
|
for (Use &U : ToBePromoted->operands()) {
|
|
Value *Val = U.get();
|
|
Value *NewVal = nullptr;
|
|
if (Val == Transition)
|
|
NewVal = Transition->getOperand(getTransitionOriginalValueIdx());
|
|
else if (isa<UndefValue>(Val) || isa<ConstantInt>(Val) ||
|
|
isa<ConstantFP>(Val)) {
|
|
// Use a splat constant if it is not safe to use undef.
|
|
NewVal = getConstantVector(
|
|
cast<Constant>(Val),
|
|
isa<UndefValue>(Val) ||
|
|
canCauseUndefinedBehavior(ToBePromoted, U.getOperandNo()));
|
|
} else
|
|
llvm_unreachable("Did you modified shouldPromote and forgot to update "
|
|
"this?");
|
|
ToBePromoted->setOperand(U.getOperandNo(), NewVal);
|
|
}
|
|
Transition->moveAfter(ToBePromoted);
|
|
Transition->setOperand(getTransitionOriginalValueIdx(), ToBePromoted);
|
|
}
|
|
|
|
/// Some targets can do store(extractelement) with one instruction.
|
|
/// Try to push the extractelement towards the stores when the target
|
|
/// has this feature and this is profitable.
|
|
bool CodeGenPrepare::optimizeExtractElementInst(Instruction *Inst) {
|
|
unsigned CombineCost = std::numeric_limits<unsigned>::max();
|
|
if (DisableStoreExtract || !TLI ||
|
|
(!StressStoreExtract &&
|
|
!TLI->canCombineStoreAndExtract(Inst->getOperand(0)->getType(),
|
|
Inst->getOperand(1), CombineCost)))
|
|
return false;
|
|
|
|
// At this point we know that Inst is a vector to scalar transition.
|
|
// Try to move it down the def-use chain, until:
|
|
// - We can combine the transition with its single use
|
|
// => we got rid of the transition.
|
|
// - We escape the current basic block
|
|
// => we would need to check that we are moving it at a cheaper place and
|
|
// we do not do that for now.
|
|
BasicBlock *Parent = Inst->getParent();
|
|
LLVM_DEBUG(dbgs() << "Found an interesting transition: " << *Inst << '\n');
|
|
VectorPromoteHelper VPH(*DL, *TLI, *TTI, Inst, CombineCost);
|
|
// If the transition has more than one use, assume this is not going to be
|
|
// beneficial.
|
|
while (Inst->hasOneUse()) {
|
|
Instruction *ToBePromoted = cast<Instruction>(*Inst->user_begin());
|
|
LLVM_DEBUG(dbgs() << "Use: " << *ToBePromoted << '\n');
|
|
|
|
if (ToBePromoted->getParent() != Parent) {
|
|
LLVM_DEBUG(dbgs() << "Instruction to promote is in a different block ("
|
|
<< ToBePromoted->getParent()->getName()
|
|
<< ") than the transition (" << Parent->getName()
|
|
<< ").\n");
|
|
return false;
|
|
}
|
|
|
|
if (VPH.canCombine(ToBePromoted)) {
|
|
LLVM_DEBUG(dbgs() << "Assume " << *Inst << '\n'
|
|
<< "will be combined with: " << *ToBePromoted << '\n');
|
|
VPH.recordCombineInstruction(ToBePromoted);
|
|
bool Changed = VPH.promote();
|
|
NumStoreExtractExposed += Changed;
|
|
return Changed;
|
|
}
|
|
|
|
LLVM_DEBUG(dbgs() << "Try promoting.\n");
|
|
if (!VPH.canPromote(ToBePromoted) || !VPH.shouldPromote(ToBePromoted))
|
|
return false;
|
|
|
|
LLVM_DEBUG(dbgs() << "Promoting is possible... Enqueue for promotion!\n");
|
|
|
|
VPH.enqueueForPromotion(ToBePromoted);
|
|
Inst = ToBePromoted;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
/// For the instruction sequence of store below, F and I values
|
|
/// are bundled together as an i64 value before being stored into memory.
|
|
/// Sometimes it is more efficient to generate separate stores for F and I,
|
|
/// which can remove the bitwise instructions or sink them to colder places.
|
|
///
|
|
/// (store (or (zext (bitcast F to i32) to i64),
|
|
/// (shl (zext I to i64), 32)), addr) -->
|
|
/// (store F, addr) and (store I, addr+4)
|
|
///
|
|
/// Similarly, splitting for other merged store can also be beneficial, like:
|
|
/// For pair of {i32, i32}, i64 store --> two i32 stores.
|
|
/// For pair of {i32, i16}, i64 store --> two i32 stores.
|
|
/// For pair of {i16, i16}, i32 store --> two i16 stores.
|
|
/// For pair of {i16, i8}, i32 store --> two i16 stores.
|
|
/// For pair of {i8, i8}, i16 store --> two i8 stores.
|
|
///
|
|
/// We allow each target to determine specifically which kind of splitting is
|
|
/// supported.
|
|
///
|
|
/// The store patterns are commonly seen from the simple code snippet below
|
|
/// if only std::make_pair(...) is sroa transformed before inlined into hoo.
|
|
/// void goo(const std::pair<int, float> &);
|
|
/// hoo() {
|
|
/// ...
|
|
/// goo(std::make_pair(tmp, ftmp));
|
|
/// ...
|
|
/// }
|
|
///
|
|
/// Although we already have similar splitting in DAG Combine, we duplicate
|
|
/// it in CodeGenPrepare to catch the case in which pattern is across
|
|
/// multiple BBs. The logic in DAG Combine is kept to catch case generated
|
|
/// during code expansion.
|
|
static bool splitMergedValStore(StoreInst &SI, const DataLayout &DL,
|
|
const TargetLowering &TLI) {
|
|
// Handle simple but common cases only.
|
|
Type *StoreType = SI.getValueOperand()->getType();
|
|
if (DL.getTypeStoreSizeInBits(StoreType) != DL.getTypeSizeInBits(StoreType) ||
|
|
DL.getTypeSizeInBits(StoreType) == 0)
|
|
return false;
|
|
|
|
unsigned HalfValBitSize = DL.getTypeSizeInBits(StoreType) / 2;
|
|
Type *SplitStoreType = Type::getIntNTy(SI.getContext(), HalfValBitSize);
|
|
if (DL.getTypeStoreSizeInBits(SplitStoreType) !=
|
|
DL.getTypeSizeInBits(SplitStoreType))
|
|
return false;
|
|
|
|
// Match the following patterns:
|
|
// (store (or (zext LValue to i64),
|
|
// (shl (zext HValue to i64), 32)), HalfValBitSize)
|
|
// or
|
|
// (store (or (shl (zext HValue to i64), 32)), HalfValBitSize)
|
|
// (zext LValue to i64),
|
|
// Expect both operands of OR and the first operand of SHL have only
|
|
// one use.
|
|
Value *LValue, *HValue;
|
|
if (!match(SI.getValueOperand(),
|
|
m_c_Or(m_OneUse(m_ZExt(m_Value(LValue))),
|
|
m_OneUse(m_Shl(m_OneUse(m_ZExt(m_Value(HValue))),
|
|
m_SpecificInt(HalfValBitSize))))))
|
|
return false;
|
|
|
|
// Check LValue and HValue are int with size less or equal than 32.
|
|
if (!LValue->getType()->isIntegerTy() ||
|
|
DL.getTypeSizeInBits(LValue->getType()) > HalfValBitSize ||
|
|
!HValue->getType()->isIntegerTy() ||
|
|
DL.getTypeSizeInBits(HValue->getType()) > HalfValBitSize)
|
|
return false;
|
|
|
|
// If LValue/HValue is a bitcast instruction, use the EVT before bitcast
|
|
// as the input of target query.
|
|
auto *LBC = dyn_cast<BitCastInst>(LValue);
|
|
auto *HBC = dyn_cast<BitCastInst>(HValue);
|
|
EVT LowTy = LBC ? EVT::getEVT(LBC->getOperand(0)->getType())
|
|
: EVT::getEVT(LValue->getType());
|
|
EVT HighTy = HBC ? EVT::getEVT(HBC->getOperand(0)->getType())
|
|
: EVT::getEVT(HValue->getType());
|
|
if (!ForceSplitStore && !TLI.isMultiStoresCheaperThanBitsMerge(LowTy, HighTy))
|
|
return false;
|
|
|
|
// Start to split store.
|
|
IRBuilder<> Builder(SI.getContext());
|
|
Builder.SetInsertPoint(&SI);
|
|
|
|
// If LValue/HValue is a bitcast in another BB, create a new one in current
|
|
// BB so it may be merged with the splitted stores by dag combiner.
|
|
if (LBC && LBC->getParent() != SI.getParent())
|
|
LValue = Builder.CreateBitCast(LBC->getOperand(0), LBC->getType());
|
|
if (HBC && HBC->getParent() != SI.getParent())
|
|
HValue = Builder.CreateBitCast(HBC->getOperand(0), HBC->getType());
|
|
|
|
bool IsLE = SI.getModule()->getDataLayout().isLittleEndian();
|
|
auto CreateSplitStore = [&](Value *V, bool Upper) {
|
|
V = Builder.CreateZExtOrBitCast(V, SplitStoreType);
|
|
Value *Addr = Builder.CreateBitCast(
|
|
SI.getOperand(1),
|
|
SplitStoreType->getPointerTo(SI.getPointerAddressSpace()));
|
|
if ((IsLE && Upper) || (!IsLE && !Upper))
|
|
Addr = Builder.CreateGEP(
|
|
SplitStoreType, Addr,
|
|
ConstantInt::get(Type::getInt32Ty(SI.getContext()), 1));
|
|
Builder.CreateAlignedStore(
|
|
V, Addr, Upper ? SI.getAlignment() / 2 : SI.getAlignment());
|
|
};
|
|
|
|
CreateSplitStore(LValue, false);
|
|
CreateSplitStore(HValue, true);
|
|
|
|
// Delete the old store.
|
|
SI.eraseFromParent();
|
|
return true;
|
|
}
|
|
|
|
// Return true if the GEP has two operands, the first operand is of a sequential
|
|
// type, and the second operand is a constant.
|
|
static bool GEPSequentialConstIndexed(GetElementPtrInst *GEP) {
|
|
gep_type_iterator I = gep_type_begin(*GEP);
|
|
return GEP->getNumOperands() == 2 &&
|
|
I.isSequential() &&
|
|
isa<ConstantInt>(GEP->getOperand(1));
|
|
}
|
|
|
|
// Try unmerging GEPs to reduce liveness interference (register pressure) across
|
|
// IndirectBr edges. Since IndirectBr edges tend to touch on many blocks,
|
|
// reducing liveness interference across those edges benefits global register
|
|
// allocation. Currently handles only certain cases.
|
|
//
|
|
// For example, unmerge %GEPI and %UGEPI as below.
|
|
//
|
|
// ---------- BEFORE ----------
|
|
// SrcBlock:
|
|
// ...
|
|
// %GEPIOp = ...
|
|
// ...
|
|
// %GEPI = gep %GEPIOp, Idx
|
|
// ...
|
|
// indirectbr ... [ label %DstB0, label %DstB1, ... label %DstBi ... ]
|
|
// (* %GEPI is alive on the indirectbr edges due to other uses ahead)
|
|
// (* %GEPIOp is alive on the indirectbr edges only because of it's used by
|
|
// %UGEPI)
|
|
//
|
|
// DstB0: ... (there may be a gep similar to %UGEPI to be unmerged)
|
|
// DstB1: ... (there may be a gep similar to %UGEPI to be unmerged)
|
|
// ...
|
|
//
|
|
// DstBi:
|
|
// ...
|
|
// %UGEPI = gep %GEPIOp, UIdx
|
|
// ...
|
|
// ---------------------------
|
|
//
|
|
// ---------- AFTER ----------
|
|
// SrcBlock:
|
|
// ... (same as above)
|
|
// (* %GEPI is still alive on the indirectbr edges)
|
|
// (* %GEPIOp is no longer alive on the indirectbr edges as a result of the
|
|
// unmerging)
|
|
// ...
|
|
//
|
|
// DstBi:
|
|
// ...
|
|
// %UGEPI = gep %GEPI, (UIdx-Idx)
|
|
// ...
|
|
// ---------------------------
|
|
//
|
|
// The register pressure on the IndirectBr edges is reduced because %GEPIOp is
|
|
// no longer alive on them.
|
|
//
|
|
// We try to unmerge GEPs here in CodGenPrepare, as opposed to limiting merging
|
|
// of GEPs in the first place in InstCombiner::visitGetElementPtrInst() so as
|
|
// not to disable further simplications and optimizations as a result of GEP
|
|
// merging.
|
|
//
|
|
// Note this unmerging may increase the length of the data flow critical path
|
|
// (the path from %GEPIOp to %UGEPI would go through %GEPI), which is a tradeoff
|
|
// between the register pressure and the length of data-flow critical
|
|
// path. Restricting this to the uncommon IndirectBr case would minimize the
|
|
// impact of potentially longer critical path, if any, and the impact on compile
|
|
// time.
|
|
static bool tryUnmergingGEPsAcrossIndirectBr(GetElementPtrInst *GEPI,
|
|
const TargetTransformInfo *TTI) {
|
|
BasicBlock *SrcBlock = GEPI->getParent();
|
|
// Check that SrcBlock ends with an IndirectBr. If not, give up. The common
|
|
// (non-IndirectBr) cases exit early here.
|
|
if (!isa<IndirectBrInst>(SrcBlock->getTerminator()))
|
|
return false;
|
|
// Check that GEPI is a simple gep with a single constant index.
|
|
if (!GEPSequentialConstIndexed(GEPI))
|
|
return false;
|
|
ConstantInt *GEPIIdx = cast<ConstantInt>(GEPI->getOperand(1));
|
|
// Check that GEPI is a cheap one.
|
|
if (TTI->getIntImmCost(GEPIIdx->getValue(), GEPIIdx->getType())
|
|
> TargetTransformInfo::TCC_Basic)
|
|
return false;
|
|
Value *GEPIOp = GEPI->getOperand(0);
|
|
// Check that GEPIOp is an instruction that's also defined in SrcBlock.
|
|
if (!isa<Instruction>(GEPIOp))
|
|
return false;
|
|
auto *GEPIOpI = cast<Instruction>(GEPIOp);
|
|
if (GEPIOpI->getParent() != SrcBlock)
|
|
return false;
|
|
// Check that GEP is used outside the block, meaning it's alive on the
|
|
// IndirectBr edge(s).
|
|
if (find_if(GEPI->users(), [&](User *Usr) {
|
|
if (auto *I = dyn_cast<Instruction>(Usr)) {
|
|
if (I->getParent() != SrcBlock) {
|
|
return true;
|
|
}
|
|
}
|
|
return false;
|
|
}) == GEPI->users().end())
|
|
return false;
|
|
// The second elements of the GEP chains to be unmerged.
|
|
std::vector<GetElementPtrInst *> UGEPIs;
|
|
// Check each user of GEPIOp to check if unmerging would make GEPIOp not alive
|
|
// on IndirectBr edges.
|
|
for (User *Usr : GEPIOp->users()) {
|
|
if (Usr == GEPI) continue;
|
|
// Check if Usr is an Instruction. If not, give up.
|
|
if (!isa<Instruction>(Usr))
|
|
return false;
|
|
auto *UI = cast<Instruction>(Usr);
|
|
// Check if Usr in the same block as GEPIOp, which is fine, skip.
|
|
if (UI->getParent() == SrcBlock)
|
|
continue;
|
|
// Check if Usr is a GEP. If not, give up.
|
|
if (!isa<GetElementPtrInst>(Usr))
|
|
return false;
|
|
auto *UGEPI = cast<GetElementPtrInst>(Usr);
|
|
// Check if UGEPI is a simple gep with a single constant index and GEPIOp is
|
|
// the pointer operand to it. If so, record it in the vector. If not, give
|
|
// up.
|
|
if (!GEPSequentialConstIndexed(UGEPI))
|
|
return false;
|
|
if (UGEPI->getOperand(0) != GEPIOp)
|
|
return false;
|
|
if (GEPIIdx->getType() !=
|
|
cast<ConstantInt>(UGEPI->getOperand(1))->getType())
|
|
return false;
|
|
ConstantInt *UGEPIIdx = cast<ConstantInt>(UGEPI->getOperand(1));
|
|
if (TTI->getIntImmCost(UGEPIIdx->getValue(), UGEPIIdx->getType())
|
|
> TargetTransformInfo::TCC_Basic)
|
|
return false;
|
|
UGEPIs.push_back(UGEPI);
|
|
}
|
|
if (UGEPIs.size() == 0)
|
|
return false;
|
|
// Check the materializing cost of (Uidx-Idx).
|
|
for (GetElementPtrInst *UGEPI : UGEPIs) {
|
|
ConstantInt *UGEPIIdx = cast<ConstantInt>(UGEPI->getOperand(1));
|
|
APInt NewIdx = UGEPIIdx->getValue() - GEPIIdx->getValue();
|
|
unsigned ImmCost = TTI->getIntImmCost(NewIdx, GEPIIdx->getType());
|
|
if (ImmCost > TargetTransformInfo::TCC_Basic)
|
|
return false;
|
|
}
|
|
// Now unmerge between GEPI and UGEPIs.
|
|
for (GetElementPtrInst *UGEPI : UGEPIs) {
|
|
UGEPI->setOperand(0, GEPI);
|
|
ConstantInt *UGEPIIdx = cast<ConstantInt>(UGEPI->getOperand(1));
|
|
Constant *NewUGEPIIdx =
|
|
ConstantInt::get(GEPIIdx->getType(),
|
|
UGEPIIdx->getValue() - GEPIIdx->getValue());
|
|
UGEPI->setOperand(1, NewUGEPIIdx);
|
|
// If GEPI is not inbounds but UGEPI is inbounds, change UGEPI to not
|
|
// inbounds to avoid UB.
|
|
if (!GEPI->isInBounds()) {
|
|
UGEPI->setIsInBounds(false);
|
|
}
|
|
}
|
|
// After unmerging, verify that GEPIOp is actually only used in SrcBlock (not
|
|
// alive on IndirectBr edges).
|
|
assert(find_if(GEPIOp->users(), [&](User *Usr) {
|
|
return cast<Instruction>(Usr)->getParent() != SrcBlock;
|
|
}) == GEPIOp->users().end() && "GEPIOp is used outside SrcBlock");
|
|
return true;
|
|
}
|
|
|
|
bool CodeGenPrepare::optimizeInst(Instruction *I, bool &ModifiedDT) {
|
|
// Bail out if we inserted the instruction to prevent optimizations from
|
|
// stepping on each other's toes.
|
|
if (InsertedInsts.count(I))
|
|
return false;
|
|
|
|
if (PHINode *P = dyn_cast<PHINode>(I)) {
|
|
// It is possible for very late stage optimizations (such as SimplifyCFG)
|
|
// to introduce PHI nodes too late to be cleaned up. If we detect such a
|
|
// trivial PHI, go ahead and zap it here.
|
|
if (Value *V = SimplifyInstruction(P, {*DL, TLInfo})) {
|
|
P->replaceAllUsesWith(V);
|
|
P->eraseFromParent();
|
|
++NumPHIsElim;
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
if (CastInst *CI = dyn_cast<CastInst>(I)) {
|
|
// If the source of the cast is a constant, then this should have
|
|
// already been constant folded. The only reason NOT to constant fold
|
|
// it is if something (e.g. LSR) was careful to place the constant
|
|
// evaluation in a block other than then one that uses it (e.g. to hoist
|
|
// the address of globals out of a loop). If this is the case, we don't
|
|
// want to forward-subst the cast.
|
|
if (isa<Constant>(CI->getOperand(0)))
|
|
return false;
|
|
|
|
if (TLI && OptimizeNoopCopyExpression(CI, *TLI, *DL))
|
|
return true;
|
|
|
|
if (isa<ZExtInst>(I) || isa<SExtInst>(I)) {
|
|
/// Sink a zext or sext into its user blocks if the target type doesn't
|
|
/// fit in one register
|
|
if (TLI &&
|
|
TLI->getTypeAction(CI->getContext(),
|
|
TLI->getValueType(*DL, CI->getType())) ==
|
|
TargetLowering::TypeExpandInteger) {
|
|
return SinkCast(CI);
|
|
} else {
|
|
bool MadeChange = optimizeExt(I);
|
|
return MadeChange | optimizeExtUses(I);
|
|
}
|
|
}
|
|
return false;
|
|
}
|
|
|
|
if (CmpInst *CI = dyn_cast<CmpInst>(I))
|
|
if (!TLI || !TLI->hasMultipleConditionRegisters())
|
|
return OptimizeCmpExpression(CI, TLI);
|
|
|
|
if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
|
|
LI->setMetadata(LLVMContext::MD_invariant_group, nullptr);
|
|
if (TLI) {
|
|
bool Modified = optimizeLoadExt(LI);
|
|
unsigned AS = LI->getPointerAddressSpace();
|
|
Modified |= optimizeMemoryInst(I, I->getOperand(0), LI->getType(), AS);
|
|
return Modified;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
|
|
if (TLI && splitMergedValStore(*SI, *DL, *TLI))
|
|
return true;
|
|
SI->setMetadata(LLVMContext::MD_invariant_group, nullptr);
|
|
if (TLI) {
|
|
unsigned AS = SI->getPointerAddressSpace();
|
|
return optimizeMemoryInst(I, SI->getOperand(1),
|
|
SI->getOperand(0)->getType(), AS);
|
|
}
|
|
return false;
|
|
}
|
|
|
|
if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
|
|
unsigned AS = RMW->getPointerAddressSpace();
|
|
return optimizeMemoryInst(I, RMW->getPointerOperand(),
|
|
RMW->getType(), AS);
|
|
}
|
|
|
|
if (AtomicCmpXchgInst *CmpX = dyn_cast<AtomicCmpXchgInst>(I)) {
|
|
unsigned AS = CmpX->getPointerAddressSpace();
|
|
return optimizeMemoryInst(I, CmpX->getPointerOperand(),
|
|
CmpX->getCompareOperand()->getType(), AS);
|
|
}
|
|
|
|
BinaryOperator *BinOp = dyn_cast<BinaryOperator>(I);
|
|
|
|
if (BinOp && (BinOp->getOpcode() == Instruction::And) &&
|
|
EnableAndCmpSinking && TLI)
|
|
return sinkAndCmp0Expression(BinOp, *TLI, InsertedInsts);
|
|
|
|
if (BinOp && (BinOp->getOpcode() == Instruction::AShr ||
|
|
BinOp->getOpcode() == Instruction::LShr)) {
|
|
ConstantInt *CI = dyn_cast<ConstantInt>(BinOp->getOperand(1));
|
|
if (TLI && CI && TLI->hasExtractBitsInsn())
|
|
return OptimizeExtractBits(BinOp, CI, *TLI, *DL);
|
|
|
|
return false;
|
|
}
|
|
|
|
if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(I)) {
|
|
if (GEPI->hasAllZeroIndices()) {
|
|
/// The GEP operand must be a pointer, so must its result -> BitCast
|
|
Instruction *NC = new BitCastInst(GEPI->getOperand(0), GEPI->getType(),
|
|
GEPI->getName(), GEPI);
|
|
NC->setDebugLoc(GEPI->getDebugLoc());
|
|
GEPI->replaceAllUsesWith(NC);
|
|
GEPI->eraseFromParent();
|
|
++NumGEPsElim;
|
|
optimizeInst(NC, ModifiedDT);
|
|
return true;
|
|
}
|
|
if (tryUnmergingGEPsAcrossIndirectBr(GEPI, TTI)) {
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
if (CallInst *CI = dyn_cast<CallInst>(I))
|
|
return optimizeCallInst(CI, ModifiedDT);
|
|
|
|
if (SelectInst *SI = dyn_cast<SelectInst>(I))
|
|
return optimizeSelectInst(SI);
|
|
|
|
if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(I))
|
|
return optimizeShuffleVectorInst(SVI);
|
|
|
|
if (auto *Switch = dyn_cast<SwitchInst>(I))
|
|
return optimizeSwitchInst(Switch);
|
|
|
|
if (isa<ExtractElementInst>(I))
|
|
return optimizeExtractElementInst(I);
|
|
|
|
return false;
|
|
}
|
|
|
|
/// Given an OR instruction, check to see if this is a bitreverse
|
|
/// idiom. If so, insert the new intrinsic and return true.
|
|
static bool makeBitReverse(Instruction &I, const DataLayout &DL,
|
|
const TargetLowering &TLI) {
|
|
if (!I.getType()->isIntegerTy() ||
|
|
!TLI.isOperationLegalOrCustom(ISD::BITREVERSE,
|
|
TLI.getValueType(DL, I.getType(), true)))
|
|
return false;
|
|
|
|
SmallVector<Instruction*, 4> Insts;
|
|
if (!recognizeBSwapOrBitReverseIdiom(&I, false, true, Insts))
|
|
return false;
|
|
Instruction *LastInst = Insts.back();
|
|
I.replaceAllUsesWith(LastInst);
|
|
RecursivelyDeleteTriviallyDeadInstructions(&I);
|
|
return true;
|
|
}
|
|
|
|
// In this pass we look for GEP and cast instructions that are used
|
|
// across basic blocks and rewrite them to improve basic-block-at-a-time
|
|
// selection.
|
|
bool CodeGenPrepare::optimizeBlock(BasicBlock &BB, bool &ModifiedDT) {
|
|
SunkAddrs.clear();
|
|
bool MadeChange = false;
|
|
|
|
CurInstIterator = BB.begin();
|
|
while (CurInstIterator != BB.end()) {
|
|
MadeChange |= optimizeInst(&*CurInstIterator++, ModifiedDT);
|
|
if (ModifiedDT)
|
|
return true;
|
|
}
|
|
|
|
bool MadeBitReverse = true;
|
|
while (TLI && MadeBitReverse) {
|
|
MadeBitReverse = false;
|
|
for (auto &I : reverse(BB)) {
|
|
if (makeBitReverse(I, *DL, *TLI)) {
|
|
MadeBitReverse = MadeChange = true;
|
|
ModifiedDT = true;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
MadeChange |= dupRetToEnableTailCallOpts(&BB);
|
|
|
|
return MadeChange;
|
|
}
|
|
|
|
// llvm.dbg.value is far away from the value then iSel may not be able
|
|
// handle it properly. iSel will drop llvm.dbg.value if it can not
|
|
// find a node corresponding to the value.
|
|
bool CodeGenPrepare::placeDbgValues(Function &F) {
|
|
bool MadeChange = false;
|
|
for (BasicBlock &BB : F) {
|
|
Instruction *PrevNonDbgInst = nullptr;
|
|
for (BasicBlock::iterator BI = BB.begin(), BE = BB.end(); BI != BE;) {
|
|
Instruction *Insn = &*BI++;
|
|
DbgValueInst *DVI = dyn_cast<DbgValueInst>(Insn);
|
|
// Leave dbg.values that refer to an alloca alone. These
|
|
// intrinsics describe the address of a variable (= the alloca)
|
|
// being taken. They should not be moved next to the alloca
|
|
// (and to the beginning of the scope), but rather stay close to
|
|
// where said address is used.
|
|
if (!DVI || (DVI->getValue() && isa<AllocaInst>(DVI->getValue()))) {
|
|
PrevNonDbgInst = Insn;
|
|
continue;
|
|
}
|
|
|
|
Instruction *VI = dyn_cast_or_null<Instruction>(DVI->getValue());
|
|
if (VI && VI != PrevNonDbgInst && !VI->isTerminator()) {
|
|
// If VI is a phi in a block with an EHPad terminator, we can't insert
|
|
// after it.
|
|
if (isa<PHINode>(VI) && VI->getParent()->getTerminator()->isEHPad())
|
|
continue;
|
|
LLVM_DEBUG(dbgs() << "Moving Debug Value before :\n"
|
|
<< *DVI << ' ' << *VI);
|
|
DVI->removeFromParent();
|
|
if (isa<PHINode>(VI))
|
|
DVI->insertBefore(&*VI->getParent()->getFirstInsertionPt());
|
|
else
|
|
DVI->insertAfter(VI);
|
|
MadeChange = true;
|
|
++NumDbgValueMoved;
|
|
}
|
|
}
|
|
}
|
|
return MadeChange;
|
|
}
|
|
|
|
/// Scale down both weights to fit into uint32_t.
|
|
static void scaleWeights(uint64_t &NewTrue, uint64_t &NewFalse) {
|
|
uint64_t NewMax = (NewTrue > NewFalse) ? NewTrue : NewFalse;
|
|
uint32_t Scale = (NewMax / std::numeric_limits<uint32_t>::max()) + 1;
|
|
NewTrue = NewTrue / Scale;
|
|
NewFalse = NewFalse / Scale;
|
|
}
|
|
|
|
/// Some targets prefer to split a conditional branch like:
|
|
/// \code
|
|
/// %0 = icmp ne i32 %a, 0
|
|
/// %1 = icmp ne i32 %b, 0
|
|
/// %or.cond = or i1 %0, %1
|
|
/// br i1 %or.cond, label %TrueBB, label %FalseBB
|
|
/// \endcode
|
|
/// into multiple branch instructions like:
|
|
/// \code
|
|
/// bb1:
|
|
/// %0 = icmp ne i32 %a, 0
|
|
/// br i1 %0, label %TrueBB, label %bb2
|
|
/// bb2:
|
|
/// %1 = icmp ne i32 %b, 0
|
|
/// br i1 %1, label %TrueBB, label %FalseBB
|
|
/// \endcode
|
|
/// This usually allows instruction selection to do even further optimizations
|
|
/// and combine the compare with the branch instruction. Currently this is
|
|
/// applied for targets which have "cheap" jump instructions.
|
|
///
|
|
/// FIXME: Remove the (equivalent?) implementation in SelectionDAG.
|
|
///
|
|
bool CodeGenPrepare::splitBranchCondition(Function &F) {
|
|
if (!TM || !TM->Options.EnableFastISel || !TLI || TLI->isJumpExpensive())
|
|
return false;
|
|
|
|
bool MadeChange = false;
|
|
for (auto &BB : F) {
|
|
// Does this BB end with the following?
|
|
// %cond1 = icmp|fcmp|binary instruction ...
|
|
// %cond2 = icmp|fcmp|binary instruction ...
|
|
// %cond.or = or|and i1 %cond1, cond2
|
|
// br i1 %cond.or label %dest1, label %dest2"
|
|
BinaryOperator *LogicOp;
|
|
BasicBlock *TBB, *FBB;
|
|
if (!match(BB.getTerminator(), m_Br(m_OneUse(m_BinOp(LogicOp)), TBB, FBB)))
|
|
continue;
|
|
|
|
auto *Br1 = cast<BranchInst>(BB.getTerminator());
|
|
if (Br1->getMetadata(LLVMContext::MD_unpredictable))
|
|
continue;
|
|
|
|
unsigned Opc;
|
|
Value *Cond1, *Cond2;
|
|
if (match(LogicOp, m_And(m_OneUse(m_Value(Cond1)),
|
|
m_OneUse(m_Value(Cond2)))))
|
|
Opc = Instruction::And;
|
|
else if (match(LogicOp, m_Or(m_OneUse(m_Value(Cond1)),
|
|
m_OneUse(m_Value(Cond2)))))
|
|
Opc = Instruction::Or;
|
|
else
|
|
continue;
|
|
|
|
if (!match(Cond1, m_CombineOr(m_Cmp(), m_BinOp())) ||
|
|
!match(Cond2, m_CombineOr(m_Cmp(), m_BinOp())) )
|
|
continue;
|
|
|
|
LLVM_DEBUG(dbgs() << "Before branch condition splitting\n"; BB.dump());
|
|
|
|
// Create a new BB.
|
|
auto TmpBB =
|
|
BasicBlock::Create(BB.getContext(), BB.getName() + ".cond.split",
|
|
BB.getParent(), BB.getNextNode());
|
|
|
|
// Update original basic block by using the first condition directly by the
|
|
// branch instruction and removing the no longer needed and/or instruction.
|
|
Br1->setCondition(Cond1);
|
|
LogicOp->eraseFromParent();
|
|
|
|
// Depending on the condition we have to either replace the true or the
|
|
// false successor of the original branch instruction.
|
|
if (Opc == Instruction::And)
|
|
Br1->setSuccessor(0, TmpBB);
|
|
else
|
|
Br1->setSuccessor(1, TmpBB);
|
|
|
|
// Fill in the new basic block.
|
|
auto *Br2 = IRBuilder<>(TmpBB).CreateCondBr(Cond2, TBB, FBB);
|
|
if (auto *I = dyn_cast<Instruction>(Cond2)) {
|
|
I->removeFromParent();
|
|
I->insertBefore(Br2);
|
|
}
|
|
|
|
// Update PHI nodes in both successors. The original BB needs to be
|
|
// replaced in one successor's PHI nodes, because the branch comes now from
|
|
// the newly generated BB (NewBB). In the other successor we need to add one
|
|
// incoming edge to the PHI nodes, because both branch instructions target
|
|
// now the same successor. Depending on the original branch condition
|
|
// (and/or) we have to swap the successors (TrueDest, FalseDest), so that
|
|
// we perform the correct update for the PHI nodes.
|
|
// This doesn't change the successor order of the just created branch
|
|
// instruction (or any other instruction).
|
|
if (Opc == Instruction::Or)
|
|
std::swap(TBB, FBB);
|
|
|
|
// Replace the old BB with the new BB.
|
|
for (PHINode &PN : TBB->phis()) {
|
|
int i;
|
|
while ((i = PN.getBasicBlockIndex(&BB)) >= 0)
|
|
PN.setIncomingBlock(i, TmpBB);
|
|
}
|
|
|
|
// Add another incoming edge form the new BB.
|
|
for (PHINode &PN : FBB->phis()) {
|
|
auto *Val = PN.getIncomingValueForBlock(&BB);
|
|
PN.addIncoming(Val, TmpBB);
|
|
}
|
|
|
|
// Update the branch weights (from SelectionDAGBuilder::
|
|
// FindMergedConditions).
|
|
if (Opc == Instruction::Or) {
|
|
// Codegen X | Y as:
|
|
// BB1:
|
|
// jmp_if_X TBB
|
|
// jmp TmpBB
|
|
// TmpBB:
|
|
// jmp_if_Y TBB
|
|
// jmp FBB
|
|
//
|
|
|
|
// We have flexibility in setting Prob for BB1 and Prob for NewBB.
|
|
// The requirement is that
|
|
// TrueProb for BB1 + (FalseProb for BB1 * TrueProb for TmpBB)
|
|
// = TrueProb for original BB.
|
|
// Assuming the original weights are A and B, one choice is to set BB1's
|
|
// weights to A and A+2B, and set TmpBB's weights to A and 2B. This choice
|
|
// assumes that
|
|
// TrueProb for BB1 == FalseProb for BB1 * TrueProb for TmpBB.
|
|
// Another choice is to assume TrueProb for BB1 equals to TrueProb for
|
|
// TmpBB, but the math is more complicated.
|
|
uint64_t TrueWeight, FalseWeight;
|
|
if (Br1->extractProfMetadata(TrueWeight, FalseWeight)) {
|
|
uint64_t NewTrueWeight = TrueWeight;
|
|
uint64_t NewFalseWeight = TrueWeight + 2 * FalseWeight;
|
|
scaleWeights(NewTrueWeight, NewFalseWeight);
|
|
Br1->setMetadata(LLVMContext::MD_prof, MDBuilder(Br1->getContext())
|
|
.createBranchWeights(TrueWeight, FalseWeight));
|
|
|
|
NewTrueWeight = TrueWeight;
|
|
NewFalseWeight = 2 * FalseWeight;
|
|
scaleWeights(NewTrueWeight, NewFalseWeight);
|
|
Br2->setMetadata(LLVMContext::MD_prof, MDBuilder(Br2->getContext())
|
|
.createBranchWeights(TrueWeight, FalseWeight));
|
|
}
|
|
} else {
|
|
// Codegen X & Y as:
|
|
// BB1:
|
|
// jmp_if_X TmpBB
|
|
// jmp FBB
|
|
// TmpBB:
|
|
// jmp_if_Y TBB
|
|
// jmp FBB
|
|
//
|
|
// This requires creation of TmpBB after CurBB.
|
|
|
|
// We have flexibility in setting Prob for BB1 and Prob for TmpBB.
|
|
// The requirement is that
|
|
// FalseProb for BB1 + (TrueProb for BB1 * FalseProb for TmpBB)
|
|
// = FalseProb for original BB.
|
|
// Assuming the original weights are A and B, one choice is to set BB1's
|
|
// weights to 2A+B and B, and set TmpBB's weights to 2A and B. This choice
|
|
// assumes that
|
|
// FalseProb for BB1 == TrueProb for BB1 * FalseProb for TmpBB.
|
|
uint64_t TrueWeight, FalseWeight;
|
|
if (Br1->extractProfMetadata(TrueWeight, FalseWeight)) {
|
|
uint64_t NewTrueWeight = 2 * TrueWeight + FalseWeight;
|
|
uint64_t NewFalseWeight = FalseWeight;
|
|
scaleWeights(NewTrueWeight, NewFalseWeight);
|
|
Br1->setMetadata(LLVMContext::MD_prof, MDBuilder(Br1->getContext())
|
|
.createBranchWeights(TrueWeight, FalseWeight));
|
|
|
|
NewTrueWeight = 2 * TrueWeight;
|
|
NewFalseWeight = FalseWeight;
|
|
scaleWeights(NewTrueWeight, NewFalseWeight);
|
|
Br2->setMetadata(LLVMContext::MD_prof, MDBuilder(Br2->getContext())
|
|
.createBranchWeights(TrueWeight, FalseWeight));
|
|
}
|
|
}
|
|
|
|
// Note: No point in getting fancy here, since the DT info is never
|
|
// available to CodeGenPrepare.
|
|
ModifiedDT = true;
|
|
|
|
MadeChange = true;
|
|
|
|
LLVM_DEBUG(dbgs() << "After branch condition splitting\n"; BB.dump();
|
|
TmpBB->dump());
|
|
}
|
|
return MadeChange;
|
|
}
|