forked from OSchip/llvm-project
1877 lines
63 KiB
C++
1877 lines
63 KiB
C++
//=- AArch64LoadStoreOptimizer.cpp - AArch64 load/store opt. pass -*- C++ -*-=//
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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 file contains a pass that performs load / store related peephole
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// optimizations. This pass should be run after register allocation.
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//
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//===----------------------------------------------------------------------===//
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#include "AArch64InstrInfo.h"
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#include "AArch64Subtarget.h"
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#include "MCTargetDesc/AArch64AddressingModes.h"
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#include "llvm/ADT/BitVector.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/CodeGen/MachineBasicBlock.h"
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#include "llvm/CodeGen/MachineFunctionPass.h"
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#include "llvm/CodeGen/MachineInstr.h"
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#include "llvm/CodeGen/MachineInstrBuilder.h"
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#include "llvm/Support/CommandLine.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/raw_ostream.h"
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#include "llvm/Target/TargetInstrInfo.h"
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#include "llvm/Target/TargetMachine.h"
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#include "llvm/Target/TargetRegisterInfo.h"
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using namespace llvm;
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#define DEBUG_TYPE "aarch64-ldst-opt"
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/// AArch64AllocLoadStoreOpt - Post-register allocation pass to combine
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/// load / store instructions to form ldp / stp instructions.
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STATISTIC(NumPairCreated, "Number of load/store pair instructions generated");
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STATISTIC(NumPostFolded, "Number of post-index updates folded");
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STATISTIC(NumPreFolded, "Number of pre-index updates folded");
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STATISTIC(NumUnscaledPairCreated,
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"Number of load/store from unscaled generated");
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STATISTIC(NumNarrowLoadsPromoted, "Number of narrow loads promoted");
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STATISTIC(NumZeroStoresPromoted, "Number of narrow zero stores promoted");
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STATISTIC(NumLoadsFromStoresPromoted, "Number of loads from stores promoted");
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// The LdStLimit limits how far we search for load/store pairs.
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static cl::opt<unsigned> LdStLimit("aarch64-load-store-scan-limit",
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cl::init(20), cl::Hidden);
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// The UpdateLimit limits how far we search for update instructions when we form
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// pre-/post-index instructions.
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static cl::opt<unsigned> UpdateLimit("aarch64-update-scan-limit", cl::init(100),
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cl::Hidden);
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namespace llvm {
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void initializeAArch64LoadStoreOptPass(PassRegistry &);
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}
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#define AARCH64_LOAD_STORE_OPT_NAME "AArch64 load / store optimization pass"
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namespace {
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typedef struct LdStPairFlags {
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// If a matching instruction is found, MergeForward is set to true if the
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// merge is to remove the first instruction and replace the second with
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// a pair-wise insn, and false if the reverse is true.
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bool MergeForward;
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// SExtIdx gives the index of the result of the load pair that must be
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// extended. The value of SExtIdx assumes that the paired load produces the
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// value in this order: (I, returned iterator), i.e., -1 means no value has
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// to be extended, 0 means I, and 1 means the returned iterator.
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int SExtIdx;
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LdStPairFlags() : MergeForward(false), SExtIdx(-1) {}
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void setMergeForward(bool V = true) { MergeForward = V; }
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bool getMergeForward() const { return MergeForward; }
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void setSExtIdx(int V) { SExtIdx = V; }
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int getSExtIdx() const { return SExtIdx; }
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} LdStPairFlags;
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struct AArch64LoadStoreOpt : public MachineFunctionPass {
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static char ID;
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AArch64LoadStoreOpt() : MachineFunctionPass(ID) {
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initializeAArch64LoadStoreOptPass(*PassRegistry::getPassRegistry());
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}
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const AArch64InstrInfo *TII;
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const TargetRegisterInfo *TRI;
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const AArch64Subtarget *Subtarget;
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// Track which registers have been modified and used.
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BitVector ModifiedRegs, UsedRegs;
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// Scan the instructions looking for a load/store that can be combined
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// with the current instruction into a load/store pair.
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// Return the matching instruction if one is found, else MBB->end().
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MachineBasicBlock::iterator findMatchingInsn(MachineBasicBlock::iterator I,
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LdStPairFlags &Flags,
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unsigned Limit);
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// Scan the instructions looking for a store that writes to the address from
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// which the current load instruction reads. Return true if one is found.
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bool findMatchingStore(MachineBasicBlock::iterator I, unsigned Limit,
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MachineBasicBlock::iterator &StoreI);
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// Merge the two instructions indicated into a single pair-wise instruction.
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// If MergeForward is true, erase the first instruction and fold its
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// operation into the second. If false, the reverse. Return the instruction
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// following the first instruction (which may change during processing).
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MachineBasicBlock::iterator
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mergePairedInsns(MachineBasicBlock::iterator I,
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MachineBasicBlock::iterator Paired,
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const LdStPairFlags &Flags);
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// Promote the load that reads directly from the address stored to.
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MachineBasicBlock::iterator
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promoteLoadFromStore(MachineBasicBlock::iterator LoadI,
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MachineBasicBlock::iterator StoreI);
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// Scan the instruction list to find a base register update that can
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// be combined with the current instruction (a load or store) using
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// pre or post indexed addressing with writeback. Scan forwards.
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MachineBasicBlock::iterator
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findMatchingUpdateInsnForward(MachineBasicBlock::iterator I,
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int UnscaledOffset, unsigned Limit);
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// Scan the instruction list to find a base register update that can
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// be combined with the current instruction (a load or store) using
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// pre or post indexed addressing with writeback. Scan backwards.
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MachineBasicBlock::iterator
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findMatchingUpdateInsnBackward(MachineBasicBlock::iterator I, unsigned Limit);
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// Find an instruction that updates the base register of the ld/st
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// instruction.
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bool isMatchingUpdateInsn(MachineInstr *MemMI, MachineInstr *MI,
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unsigned BaseReg, int Offset);
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// Merge a pre- or post-index base register update into a ld/st instruction.
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MachineBasicBlock::iterator
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mergeUpdateInsn(MachineBasicBlock::iterator I,
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MachineBasicBlock::iterator Update, bool IsPreIdx);
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// Find and merge foldable ldr/str instructions.
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bool tryToMergeLdStInst(MachineBasicBlock::iterator &MBBI);
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// Find and promote load instructions which read directly from store.
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bool tryToPromoteLoadFromStore(MachineBasicBlock::iterator &MBBI);
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// Check if converting two narrow loads into a single wider load with
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// bitfield extracts could be enabled.
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bool enableNarrowLdMerge(MachineFunction &Fn);
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bool optimizeBlock(MachineBasicBlock &MBB, bool enableNarrowLdOpt);
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bool runOnMachineFunction(MachineFunction &Fn) override;
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const char *getPassName() const override {
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return AARCH64_LOAD_STORE_OPT_NAME;
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}
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};
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char AArch64LoadStoreOpt::ID = 0;
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} // namespace
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INITIALIZE_PASS(AArch64LoadStoreOpt, "aarch64-ldst-opt",
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AARCH64_LOAD_STORE_OPT_NAME, false, false)
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static bool isUnscaledLdSt(unsigned Opc) {
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switch (Opc) {
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default:
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return false;
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case AArch64::STURSi:
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case AArch64::STURDi:
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case AArch64::STURQi:
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case AArch64::STURBBi:
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case AArch64::STURHHi:
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case AArch64::STURWi:
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case AArch64::STURXi:
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case AArch64::LDURSi:
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case AArch64::LDURDi:
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case AArch64::LDURQi:
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case AArch64::LDURWi:
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case AArch64::LDURXi:
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case AArch64::LDURSWi:
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case AArch64::LDURHHi:
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case AArch64::LDURBBi:
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case AArch64::LDURSBWi:
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case AArch64::LDURSHWi:
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return true;
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}
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}
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static bool isUnscaledLdSt(MachineInstr *MI) {
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return isUnscaledLdSt(MI->getOpcode());
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}
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static unsigned getBitExtrOpcode(MachineInstr *MI) {
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switch (MI->getOpcode()) {
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default:
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llvm_unreachable("Unexpected opcode.");
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case AArch64::LDRBBui:
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case AArch64::LDURBBi:
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case AArch64::LDRHHui:
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case AArch64::LDURHHi:
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return AArch64::UBFMWri;
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case AArch64::LDRSBWui:
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case AArch64::LDURSBWi:
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case AArch64::LDRSHWui:
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case AArch64::LDURSHWi:
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return AArch64::SBFMWri;
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}
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}
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static bool isNarrowStore(unsigned Opc) {
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switch (Opc) {
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default:
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return false;
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case AArch64::STRBBui:
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case AArch64::STURBBi:
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case AArch64::STRHHui:
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case AArch64::STURHHi:
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return true;
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}
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}
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static bool isNarrowStore(MachineInstr *MI) {
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return isNarrowStore(MI->getOpcode());
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}
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static bool isNarrowLoad(unsigned Opc) {
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switch (Opc) {
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default:
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return false;
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case AArch64::LDRHHui:
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case AArch64::LDURHHi:
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case AArch64::LDRBBui:
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case AArch64::LDURBBi:
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case AArch64::LDRSHWui:
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case AArch64::LDURSHWi:
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case AArch64::LDRSBWui:
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case AArch64::LDURSBWi:
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return true;
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}
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}
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static bool isNarrowLoad(MachineInstr *MI) {
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return isNarrowLoad(MI->getOpcode());
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}
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// Scaling factor for unscaled load or store.
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static int getMemScale(MachineInstr *MI) {
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switch (MI->getOpcode()) {
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default:
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llvm_unreachable("Opcode has unknown scale!");
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case AArch64::LDRBBui:
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case AArch64::LDURBBi:
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case AArch64::LDRSBWui:
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case AArch64::LDURSBWi:
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case AArch64::STRBBui:
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case AArch64::STURBBi:
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return 1;
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case AArch64::LDRHHui:
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case AArch64::LDURHHi:
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case AArch64::LDRSHWui:
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case AArch64::LDURSHWi:
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case AArch64::STRHHui:
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case AArch64::STURHHi:
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return 2;
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case AArch64::LDRSui:
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case AArch64::LDURSi:
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case AArch64::LDRSWui:
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case AArch64::LDURSWi:
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case AArch64::LDRWui:
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case AArch64::LDURWi:
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case AArch64::STRSui:
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case AArch64::STURSi:
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case AArch64::STRWui:
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case AArch64::STURWi:
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case AArch64::LDPSi:
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case AArch64::LDPSWi:
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case AArch64::LDPWi:
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case AArch64::STPSi:
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case AArch64::STPWi:
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return 4;
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case AArch64::LDRDui:
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case AArch64::LDURDi:
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case AArch64::LDRXui:
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case AArch64::LDURXi:
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case AArch64::STRDui:
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case AArch64::STURDi:
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case AArch64::STRXui:
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case AArch64::STURXi:
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case AArch64::LDPDi:
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case AArch64::LDPXi:
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case AArch64::STPDi:
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case AArch64::STPXi:
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return 8;
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case AArch64::LDRQui:
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case AArch64::LDURQi:
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case AArch64::STRQui:
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case AArch64::STURQi:
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case AArch64::LDPQi:
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case AArch64::STPQi:
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return 16;
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}
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}
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static unsigned getMatchingNonSExtOpcode(unsigned Opc,
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bool *IsValidLdStrOpc = nullptr) {
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if (IsValidLdStrOpc)
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*IsValidLdStrOpc = true;
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switch (Opc) {
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default:
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if (IsValidLdStrOpc)
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*IsValidLdStrOpc = false;
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return UINT_MAX;
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case AArch64::STRDui:
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case AArch64::STURDi:
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case AArch64::STRQui:
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case AArch64::STURQi:
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case AArch64::STRBBui:
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case AArch64::STURBBi:
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case AArch64::STRHHui:
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case AArch64::STURHHi:
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case AArch64::STRWui:
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case AArch64::STURWi:
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case AArch64::STRXui:
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case AArch64::STURXi:
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case AArch64::LDRDui:
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case AArch64::LDURDi:
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case AArch64::LDRQui:
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case AArch64::LDURQi:
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case AArch64::LDRWui:
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case AArch64::LDURWi:
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case AArch64::LDRXui:
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case AArch64::LDURXi:
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case AArch64::STRSui:
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case AArch64::STURSi:
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case AArch64::LDRSui:
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case AArch64::LDURSi:
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case AArch64::LDRHHui:
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case AArch64::LDURHHi:
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case AArch64::LDRBBui:
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case AArch64::LDURBBi:
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return Opc;
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case AArch64::LDRSWui:
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return AArch64::LDRWui;
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case AArch64::LDURSWi:
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return AArch64::LDURWi;
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case AArch64::LDRSBWui:
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return AArch64::LDRBBui;
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case AArch64::LDRSHWui:
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return AArch64::LDRHHui;
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case AArch64::LDURSBWi:
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return AArch64::LDURBBi;
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case AArch64::LDURSHWi:
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return AArch64::LDURHHi;
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}
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}
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static unsigned getMatchingPairOpcode(unsigned Opc) {
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switch (Opc) {
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default:
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llvm_unreachable("Opcode has no pairwise equivalent!");
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case AArch64::STRSui:
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case AArch64::STURSi:
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return AArch64::STPSi;
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case AArch64::STRDui:
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case AArch64::STURDi:
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return AArch64::STPDi;
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case AArch64::STRQui:
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case AArch64::STURQi:
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return AArch64::STPQi;
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case AArch64::STRBBui:
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return AArch64::STRHHui;
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case AArch64::STRHHui:
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return AArch64::STRWui;
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case AArch64::STURBBi:
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return AArch64::STURHHi;
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case AArch64::STURHHi:
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return AArch64::STURWi;
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case AArch64::STRWui:
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case AArch64::STURWi:
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return AArch64::STPWi;
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case AArch64::STRXui:
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case AArch64::STURXi:
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return AArch64::STPXi;
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case AArch64::LDRSui:
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case AArch64::LDURSi:
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return AArch64::LDPSi;
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case AArch64::LDRDui:
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case AArch64::LDURDi:
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return AArch64::LDPDi;
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case AArch64::LDRQui:
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case AArch64::LDURQi:
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return AArch64::LDPQi;
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case AArch64::LDRWui:
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case AArch64::LDURWi:
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return AArch64::LDPWi;
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case AArch64::LDRXui:
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case AArch64::LDURXi:
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return AArch64::LDPXi;
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case AArch64::LDRSWui:
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case AArch64::LDURSWi:
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return AArch64::LDPSWi;
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case AArch64::LDRHHui:
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case AArch64::LDRSHWui:
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return AArch64::LDRWui;
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case AArch64::LDURHHi:
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case AArch64::LDURSHWi:
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return AArch64::LDURWi;
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case AArch64::LDRBBui:
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case AArch64::LDRSBWui:
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return AArch64::LDRHHui;
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case AArch64::LDURBBi:
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case AArch64::LDURSBWi:
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return AArch64::LDURHHi;
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}
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}
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static unsigned isMatchingStore(MachineInstr *LoadInst,
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MachineInstr *StoreInst) {
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unsigned LdOpc = LoadInst->getOpcode();
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unsigned StOpc = StoreInst->getOpcode();
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switch (LdOpc) {
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default:
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llvm_unreachable("Unsupported load instruction!");
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case AArch64::LDRBBui:
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return StOpc == AArch64::STRBBui || StOpc == AArch64::STRHHui ||
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StOpc == AArch64::STRWui || StOpc == AArch64::STRXui;
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case AArch64::LDURBBi:
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return StOpc == AArch64::STURBBi || StOpc == AArch64::STURHHi ||
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StOpc == AArch64::STURWi || StOpc == AArch64::STURXi;
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case AArch64::LDRHHui:
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return StOpc == AArch64::STRHHui || StOpc == AArch64::STRWui ||
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StOpc == AArch64::STRXui;
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case AArch64::LDURHHi:
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return StOpc == AArch64::STURHHi || StOpc == AArch64::STURWi ||
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StOpc == AArch64::STURXi;
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case AArch64::LDRWui:
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return StOpc == AArch64::STRWui || StOpc == AArch64::STRXui;
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case AArch64::LDURWi:
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return StOpc == AArch64::STURWi || StOpc == AArch64::STURXi;
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case AArch64::LDRXui:
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return StOpc == AArch64::STRXui;
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case AArch64::LDURXi:
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return StOpc == AArch64::STURXi;
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}
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}
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static unsigned getPreIndexedOpcode(unsigned Opc) {
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switch (Opc) {
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default:
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llvm_unreachable("Opcode has no pre-indexed equivalent!");
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case AArch64::STRSui:
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return AArch64::STRSpre;
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case AArch64::STRDui:
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return AArch64::STRDpre;
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case AArch64::STRQui:
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return AArch64::STRQpre;
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case AArch64::STRBBui:
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return AArch64::STRBBpre;
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case AArch64::STRHHui:
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return AArch64::STRHHpre;
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case AArch64::STRWui:
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return AArch64::STRWpre;
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case AArch64::STRXui:
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return AArch64::STRXpre;
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case AArch64::LDRSui:
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return AArch64::LDRSpre;
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case AArch64::LDRDui:
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return AArch64::LDRDpre;
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case AArch64::LDRQui:
|
|
return AArch64::LDRQpre;
|
|
case AArch64::LDRBBui:
|
|
return AArch64::LDRBBpre;
|
|
case AArch64::LDRHHui:
|
|
return AArch64::LDRHHpre;
|
|
case AArch64::LDRWui:
|
|
return AArch64::LDRWpre;
|
|
case AArch64::LDRXui:
|
|
return AArch64::LDRXpre;
|
|
case AArch64::LDRSWui:
|
|
return AArch64::LDRSWpre;
|
|
case AArch64::LDPSi:
|
|
return AArch64::LDPSpre;
|
|
case AArch64::LDPSWi:
|
|
return AArch64::LDPSWpre;
|
|
case AArch64::LDPDi:
|
|
return AArch64::LDPDpre;
|
|
case AArch64::LDPQi:
|
|
return AArch64::LDPQpre;
|
|
case AArch64::LDPWi:
|
|
return AArch64::LDPWpre;
|
|
case AArch64::LDPXi:
|
|
return AArch64::LDPXpre;
|
|
case AArch64::STPSi:
|
|
return AArch64::STPSpre;
|
|
case AArch64::STPDi:
|
|
return AArch64::STPDpre;
|
|
case AArch64::STPQi:
|
|
return AArch64::STPQpre;
|
|
case AArch64::STPWi:
|
|
return AArch64::STPWpre;
|
|
case AArch64::STPXi:
|
|
return AArch64::STPXpre;
|
|
}
|
|
}
|
|
|
|
static unsigned getPostIndexedOpcode(unsigned Opc) {
|
|
switch (Opc) {
|
|
default:
|
|
llvm_unreachable("Opcode has no post-indexed wise equivalent!");
|
|
case AArch64::STRSui:
|
|
return AArch64::STRSpost;
|
|
case AArch64::STRDui:
|
|
return AArch64::STRDpost;
|
|
case AArch64::STRQui:
|
|
return AArch64::STRQpost;
|
|
case AArch64::STRBBui:
|
|
return AArch64::STRBBpost;
|
|
case AArch64::STRHHui:
|
|
return AArch64::STRHHpost;
|
|
case AArch64::STRWui:
|
|
return AArch64::STRWpost;
|
|
case AArch64::STRXui:
|
|
return AArch64::STRXpost;
|
|
case AArch64::LDRSui:
|
|
return AArch64::LDRSpost;
|
|
case AArch64::LDRDui:
|
|
return AArch64::LDRDpost;
|
|
case AArch64::LDRQui:
|
|
return AArch64::LDRQpost;
|
|
case AArch64::LDRBBui:
|
|
return AArch64::LDRBBpost;
|
|
case AArch64::LDRHHui:
|
|
return AArch64::LDRHHpost;
|
|
case AArch64::LDRWui:
|
|
return AArch64::LDRWpost;
|
|
case AArch64::LDRXui:
|
|
return AArch64::LDRXpost;
|
|
case AArch64::LDRSWui:
|
|
return AArch64::LDRSWpost;
|
|
case AArch64::LDPSi:
|
|
return AArch64::LDPSpost;
|
|
case AArch64::LDPSWi:
|
|
return AArch64::LDPSWpost;
|
|
case AArch64::LDPDi:
|
|
return AArch64::LDPDpost;
|
|
case AArch64::LDPQi:
|
|
return AArch64::LDPQpost;
|
|
case AArch64::LDPWi:
|
|
return AArch64::LDPWpost;
|
|
case AArch64::LDPXi:
|
|
return AArch64::LDPXpost;
|
|
case AArch64::STPSi:
|
|
return AArch64::STPSpost;
|
|
case AArch64::STPDi:
|
|
return AArch64::STPDpost;
|
|
case AArch64::STPQi:
|
|
return AArch64::STPQpost;
|
|
case AArch64::STPWi:
|
|
return AArch64::STPWpost;
|
|
case AArch64::STPXi:
|
|
return AArch64::STPXpost;
|
|
}
|
|
}
|
|
|
|
static bool isPairedLdSt(const MachineInstr *MI) {
|
|
switch (MI->getOpcode()) {
|
|
default:
|
|
return false;
|
|
case AArch64::LDPSi:
|
|
case AArch64::LDPSWi:
|
|
case AArch64::LDPDi:
|
|
case AArch64::LDPQi:
|
|
case AArch64::LDPWi:
|
|
case AArch64::LDPXi:
|
|
case AArch64::STPSi:
|
|
case AArch64::STPDi:
|
|
case AArch64::STPQi:
|
|
case AArch64::STPWi:
|
|
case AArch64::STPXi:
|
|
return true;
|
|
}
|
|
}
|
|
|
|
static const MachineOperand &getLdStRegOp(const MachineInstr *MI,
|
|
unsigned PairedRegOp = 0) {
|
|
assert(PairedRegOp < 2 && "Unexpected register operand idx.");
|
|
unsigned Idx = isPairedLdSt(MI) ? PairedRegOp : 0;
|
|
return MI->getOperand(Idx);
|
|
}
|
|
|
|
static const MachineOperand &getLdStBaseOp(const MachineInstr *MI) {
|
|
unsigned Idx = isPairedLdSt(MI) ? 2 : 1;
|
|
return MI->getOperand(Idx);
|
|
}
|
|
|
|
static const MachineOperand &getLdStOffsetOp(const MachineInstr *MI) {
|
|
unsigned Idx = isPairedLdSt(MI) ? 3 : 2;
|
|
return MI->getOperand(Idx);
|
|
}
|
|
|
|
static bool isLdOffsetInRangeOfSt(MachineInstr *LoadInst,
|
|
MachineInstr *StoreInst) {
|
|
assert(isMatchingStore(LoadInst, StoreInst) && "Expect only matched ld/st.");
|
|
int LoadSize = getMemScale(LoadInst);
|
|
int StoreSize = getMemScale(StoreInst);
|
|
int UnscaledStOffset = isUnscaledLdSt(StoreInst)
|
|
? getLdStOffsetOp(StoreInst).getImm()
|
|
: getLdStOffsetOp(StoreInst).getImm() * StoreSize;
|
|
int UnscaledLdOffset = isUnscaledLdSt(LoadInst)
|
|
? getLdStOffsetOp(LoadInst).getImm()
|
|
: getLdStOffsetOp(LoadInst).getImm() * LoadSize;
|
|
return (UnscaledStOffset <= UnscaledLdOffset) &&
|
|
(UnscaledLdOffset + LoadSize <= (UnscaledStOffset + StoreSize));
|
|
}
|
|
|
|
MachineBasicBlock::iterator
|
|
AArch64LoadStoreOpt::mergePairedInsns(MachineBasicBlock::iterator I,
|
|
MachineBasicBlock::iterator Paired,
|
|
const LdStPairFlags &Flags) {
|
|
MachineBasicBlock::iterator NextI = I;
|
|
++NextI;
|
|
// If NextI is the second of the two instructions to be merged, we need
|
|
// to skip one further. Either way we merge will invalidate the iterator,
|
|
// and we don't need to scan the new instruction, as it's a pairwise
|
|
// instruction, which we're not considering for further action anyway.
|
|
if (NextI == Paired)
|
|
++NextI;
|
|
|
|
int SExtIdx = Flags.getSExtIdx();
|
|
unsigned Opc =
|
|
SExtIdx == -1 ? I->getOpcode() : getMatchingNonSExtOpcode(I->getOpcode());
|
|
bool IsUnscaled = isUnscaledLdSt(Opc);
|
|
int OffsetStride = IsUnscaled ? getMemScale(I) : 1;
|
|
|
|
bool MergeForward = Flags.getMergeForward();
|
|
unsigned NewOpc = getMatchingPairOpcode(Opc);
|
|
// Insert our new paired instruction after whichever of the paired
|
|
// instructions MergeForward indicates.
|
|
MachineBasicBlock::iterator InsertionPoint = MergeForward ? Paired : I;
|
|
// Also based on MergeForward is from where we copy the base register operand
|
|
// so we get the flags compatible with the input code.
|
|
const MachineOperand &BaseRegOp =
|
|
MergeForward ? getLdStBaseOp(Paired) : getLdStBaseOp(I);
|
|
|
|
int Offset = getLdStOffsetOp(I).getImm();
|
|
int PairedOffset = getLdStOffsetOp(Paired).getImm();
|
|
bool PairedIsUnscaled = isUnscaledLdSt(Paired->getOpcode());
|
|
|
|
// We're trying to pair instructions that differ in how they are scaled.
|
|
// If I is scaled then scale the offset of Paired accordingly.
|
|
// Otherwise, do the opposite (i.e., make Paired's offset unscaled).
|
|
if (IsUnscaled != PairedIsUnscaled) {
|
|
int MemSize = getMemScale(Paired);
|
|
assert(!(PairedOffset % getMemScale(Paired)) &&
|
|
"Offset should be a multiple of the stride!");
|
|
PairedOffset =
|
|
PairedIsUnscaled ? PairedOffset / MemSize : PairedOffset * MemSize;
|
|
}
|
|
|
|
// Which register is Rt and which is Rt2 depends on the offset order.
|
|
MachineInstr *RtMI, *Rt2MI;
|
|
if (Offset == PairedOffset + OffsetStride) {
|
|
RtMI = Paired;
|
|
Rt2MI = I;
|
|
// Here we swapped the assumption made for SExtIdx.
|
|
// I.e., we turn ldp I, Paired into ldp Paired, I.
|
|
// Update the index accordingly.
|
|
if (SExtIdx != -1)
|
|
SExtIdx = (SExtIdx + 1) % 2;
|
|
} else {
|
|
RtMI = I;
|
|
Rt2MI = Paired;
|
|
}
|
|
|
|
int OffsetImm = getLdStOffsetOp(RtMI).getImm();
|
|
|
|
if (isNarrowLoad(Opc)) {
|
|
// Change the scaled offset from small to large type.
|
|
if (!IsUnscaled) {
|
|
assert(((OffsetImm & 1) == 0) && "Unexpected offset to merge");
|
|
OffsetImm /= 2;
|
|
}
|
|
MachineInstr *RtNewDest = MergeForward ? I : Paired;
|
|
// When merging small (< 32 bit) loads for big-endian targets, the order of
|
|
// the component parts gets swapped.
|
|
if (!Subtarget->isLittleEndian())
|
|
std::swap(RtMI, Rt2MI);
|
|
// Construct the new load instruction.
|
|
MachineInstr *NewMemMI, *BitExtMI1, *BitExtMI2;
|
|
NewMemMI = BuildMI(*I->getParent(), InsertionPoint, I->getDebugLoc(),
|
|
TII->get(NewOpc))
|
|
.addOperand(getLdStRegOp(RtNewDest))
|
|
.addOperand(BaseRegOp)
|
|
.addImm(OffsetImm)
|
|
.setMemRefs(I->mergeMemRefsWith(*Paired));
|
|
|
|
DEBUG(
|
|
dbgs()
|
|
<< "Creating the new load and extract. Replacing instructions:\n ");
|
|
DEBUG(I->print(dbgs()));
|
|
DEBUG(dbgs() << " ");
|
|
DEBUG(Paired->print(dbgs()));
|
|
DEBUG(dbgs() << " with instructions:\n ");
|
|
DEBUG((NewMemMI)->print(dbgs()));
|
|
|
|
int Width = getMemScale(I) == 1 ? 8 : 16;
|
|
int LSBLow = 0;
|
|
int LSBHigh = Width;
|
|
int ImmsLow = LSBLow + Width - 1;
|
|
int ImmsHigh = LSBHigh + Width - 1;
|
|
MachineInstr *ExtDestMI = MergeForward ? Paired : I;
|
|
if ((ExtDestMI == Rt2MI) == Subtarget->isLittleEndian()) {
|
|
// Create the bitfield extract for high bits.
|
|
BitExtMI1 = BuildMI(*I->getParent(), InsertionPoint, I->getDebugLoc(),
|
|
TII->get(getBitExtrOpcode(Rt2MI)))
|
|
.addOperand(getLdStRegOp(Rt2MI))
|
|
.addReg(getLdStRegOp(RtNewDest).getReg())
|
|
.addImm(LSBHigh)
|
|
.addImm(ImmsHigh);
|
|
// Create the bitfield extract for low bits.
|
|
if (RtMI->getOpcode() == getMatchingNonSExtOpcode(RtMI->getOpcode())) {
|
|
// For unsigned, prefer to use AND for low bits.
|
|
BitExtMI2 = BuildMI(*I->getParent(), InsertionPoint, I->getDebugLoc(),
|
|
TII->get(AArch64::ANDWri))
|
|
.addOperand(getLdStRegOp(RtMI))
|
|
.addReg(getLdStRegOp(RtNewDest).getReg())
|
|
.addImm(ImmsLow);
|
|
} else {
|
|
BitExtMI2 = BuildMI(*I->getParent(), InsertionPoint, I->getDebugLoc(),
|
|
TII->get(getBitExtrOpcode(RtMI)))
|
|
.addOperand(getLdStRegOp(RtMI))
|
|
.addReg(getLdStRegOp(RtNewDest).getReg())
|
|
.addImm(LSBLow)
|
|
.addImm(ImmsLow);
|
|
}
|
|
} else {
|
|
// Create the bitfield extract for low bits.
|
|
if (RtMI->getOpcode() == getMatchingNonSExtOpcode(RtMI->getOpcode())) {
|
|
// For unsigned, prefer to use AND for low bits.
|
|
BitExtMI1 = BuildMI(*I->getParent(), InsertionPoint, I->getDebugLoc(),
|
|
TII->get(AArch64::ANDWri))
|
|
.addOperand(getLdStRegOp(RtMI))
|
|
.addReg(getLdStRegOp(RtNewDest).getReg())
|
|
.addImm(ImmsLow);
|
|
} else {
|
|
BitExtMI1 = BuildMI(*I->getParent(), InsertionPoint, I->getDebugLoc(),
|
|
TII->get(getBitExtrOpcode(RtMI)))
|
|
.addOperand(getLdStRegOp(RtMI))
|
|
.addReg(getLdStRegOp(RtNewDest).getReg())
|
|
.addImm(LSBLow)
|
|
.addImm(ImmsLow);
|
|
}
|
|
|
|
// Create the bitfield extract for high bits.
|
|
BitExtMI2 = BuildMI(*I->getParent(), InsertionPoint, I->getDebugLoc(),
|
|
TII->get(getBitExtrOpcode(Rt2MI)))
|
|
.addOperand(getLdStRegOp(Rt2MI))
|
|
.addReg(getLdStRegOp(RtNewDest).getReg())
|
|
.addImm(LSBHigh)
|
|
.addImm(ImmsHigh);
|
|
}
|
|
DEBUG(dbgs() << " ");
|
|
DEBUG((BitExtMI1)->print(dbgs()));
|
|
DEBUG(dbgs() << " ");
|
|
DEBUG((BitExtMI2)->print(dbgs()));
|
|
DEBUG(dbgs() << "\n");
|
|
|
|
// Erase the old instructions.
|
|
I->eraseFromParent();
|
|
Paired->eraseFromParent();
|
|
return NextI;
|
|
}
|
|
|
|
// Construct the new instruction.
|
|
MachineInstrBuilder MIB;
|
|
if (isNarrowStore(Opc)) {
|
|
// Change the scaled offset from small to large type.
|
|
if (!IsUnscaled) {
|
|
assert(((OffsetImm & 1) == 0) && "Unexpected offset to merge");
|
|
OffsetImm /= 2;
|
|
}
|
|
MIB = BuildMI(*I->getParent(), InsertionPoint, I->getDebugLoc(),
|
|
TII->get(NewOpc))
|
|
.addOperand(getLdStRegOp(I))
|
|
.addOperand(BaseRegOp)
|
|
.addImm(OffsetImm)
|
|
.setMemRefs(I->mergeMemRefsWith(*Paired));
|
|
} else {
|
|
// Scale the immediate offset, if necessary.
|
|
if (isUnscaledLdSt(RtMI->getOpcode())) {
|
|
assert(!(OffsetImm % getMemScale(RtMI)) &&
|
|
"Offset should be a multiple of the stride!");
|
|
OffsetImm /= getMemScale(RtMI);
|
|
}
|
|
MIB = BuildMI(*I->getParent(), InsertionPoint, I->getDebugLoc(),
|
|
TII->get(NewOpc))
|
|
.addOperand(getLdStRegOp(RtMI))
|
|
.addOperand(getLdStRegOp(Rt2MI))
|
|
.addOperand(BaseRegOp)
|
|
.addImm(OffsetImm);
|
|
}
|
|
|
|
(void)MIB;
|
|
|
|
// FIXME: Do we need/want to copy the mem operands from the source
|
|
// instructions? Probably. What uses them after this?
|
|
|
|
DEBUG(dbgs() << "Creating pair load/store. Replacing instructions:\n ");
|
|
DEBUG(I->print(dbgs()));
|
|
DEBUG(dbgs() << " ");
|
|
DEBUG(Paired->print(dbgs()));
|
|
DEBUG(dbgs() << " with instruction:\n ");
|
|
|
|
if (SExtIdx != -1) {
|
|
// Generate the sign extension for the proper result of the ldp.
|
|
// I.e., with X1, that would be:
|
|
// %W1<def> = KILL %W1, %X1<imp-def>
|
|
// %X1<def> = SBFMXri %X1<kill>, 0, 31
|
|
MachineOperand &DstMO = MIB->getOperand(SExtIdx);
|
|
// Right now, DstMO has the extended register, since it comes from an
|
|
// extended opcode.
|
|
unsigned DstRegX = DstMO.getReg();
|
|
// Get the W variant of that register.
|
|
unsigned DstRegW = TRI->getSubReg(DstRegX, AArch64::sub_32);
|
|
// Update the result of LDP to use the W instead of the X variant.
|
|
DstMO.setReg(DstRegW);
|
|
DEBUG(((MachineInstr *)MIB)->print(dbgs()));
|
|
DEBUG(dbgs() << "\n");
|
|
// Make the machine verifier happy by providing a definition for
|
|
// the X register.
|
|
// Insert this definition right after the generated LDP, i.e., before
|
|
// InsertionPoint.
|
|
MachineInstrBuilder MIBKill =
|
|
BuildMI(*I->getParent(), InsertionPoint, I->getDebugLoc(),
|
|
TII->get(TargetOpcode::KILL), DstRegW)
|
|
.addReg(DstRegW)
|
|
.addReg(DstRegX, RegState::Define);
|
|
MIBKill->getOperand(2).setImplicit();
|
|
// Create the sign extension.
|
|
MachineInstrBuilder MIBSXTW =
|
|
BuildMI(*I->getParent(), InsertionPoint, I->getDebugLoc(),
|
|
TII->get(AArch64::SBFMXri), DstRegX)
|
|
.addReg(DstRegX)
|
|
.addImm(0)
|
|
.addImm(31);
|
|
(void)MIBSXTW;
|
|
DEBUG(dbgs() << " Extend operand:\n ");
|
|
DEBUG(((MachineInstr *)MIBSXTW)->print(dbgs()));
|
|
DEBUG(dbgs() << "\n");
|
|
} else {
|
|
DEBUG(((MachineInstr *)MIB)->print(dbgs()));
|
|
DEBUG(dbgs() << "\n");
|
|
}
|
|
|
|
// Erase the old instructions.
|
|
I->eraseFromParent();
|
|
Paired->eraseFromParent();
|
|
|
|
return NextI;
|
|
}
|
|
|
|
MachineBasicBlock::iterator
|
|
AArch64LoadStoreOpt::promoteLoadFromStore(MachineBasicBlock::iterator LoadI,
|
|
MachineBasicBlock::iterator StoreI) {
|
|
MachineBasicBlock::iterator NextI = LoadI;
|
|
++NextI;
|
|
|
|
int LoadSize = getMemScale(LoadI);
|
|
int StoreSize = getMemScale(StoreI);
|
|
unsigned LdRt = getLdStRegOp(LoadI).getReg();
|
|
unsigned StRt = getLdStRegOp(StoreI).getReg();
|
|
bool IsStoreXReg = TRI->getRegClass(AArch64::GPR64RegClassID)->contains(StRt);
|
|
|
|
assert((IsStoreXReg ||
|
|
TRI->getRegClass(AArch64::GPR32RegClassID)->contains(StRt)) &&
|
|
"Unexpected RegClass");
|
|
|
|
MachineInstr *BitExtMI;
|
|
if (LoadSize == StoreSize && (LoadSize == 4 || LoadSize == 8)) {
|
|
// Remove the load, if the destination register of the loads is the same
|
|
// register for stored value.
|
|
if (StRt == LdRt && LoadSize == 8) {
|
|
DEBUG(dbgs() << "Remove load instruction:\n ");
|
|
DEBUG(LoadI->print(dbgs()));
|
|
DEBUG(dbgs() << "\n");
|
|
LoadI->eraseFromParent();
|
|
return NextI;
|
|
}
|
|
// Replace the load with a mov if the load and store are in the same size.
|
|
BitExtMI =
|
|
BuildMI(*LoadI->getParent(), LoadI, LoadI->getDebugLoc(),
|
|
TII->get(IsStoreXReg ? AArch64::ORRXrs : AArch64::ORRWrs), LdRt)
|
|
.addReg(IsStoreXReg ? AArch64::XZR : AArch64::WZR)
|
|
.addReg(StRt)
|
|
.addImm(AArch64_AM::getShifterImm(AArch64_AM::LSL, 0));
|
|
} else {
|
|
// FIXME: Currently we disable this transformation in big-endian targets as
|
|
// performance and correctness are verified only in little-endian.
|
|
if (!Subtarget->isLittleEndian())
|
|
return NextI;
|
|
bool IsUnscaled = isUnscaledLdSt(LoadI);
|
|
assert(IsUnscaled == isUnscaledLdSt(StoreI) && "Unsupported ld/st match");
|
|
assert(LoadSize <= StoreSize && "Invalid load size");
|
|
int UnscaledLdOffset = IsUnscaled
|
|
? getLdStOffsetOp(LoadI).getImm()
|
|
: getLdStOffsetOp(LoadI).getImm() * LoadSize;
|
|
int UnscaledStOffset = IsUnscaled
|
|
? getLdStOffsetOp(StoreI).getImm()
|
|
: getLdStOffsetOp(StoreI).getImm() * StoreSize;
|
|
int Width = LoadSize * 8;
|
|
int Immr = 8 * (UnscaledLdOffset - UnscaledStOffset);
|
|
int Imms = Immr + Width - 1;
|
|
unsigned DestReg = IsStoreXReg
|
|
? TRI->getMatchingSuperReg(LdRt, AArch64::sub_32,
|
|
&AArch64::GPR64RegClass)
|
|
: LdRt;
|
|
|
|
assert((UnscaledLdOffset >= UnscaledStOffset &&
|
|
(UnscaledLdOffset + LoadSize) <= UnscaledStOffset + StoreSize) &&
|
|
"Invalid offset");
|
|
|
|
Immr = 8 * (UnscaledLdOffset - UnscaledStOffset);
|
|
Imms = Immr + Width - 1;
|
|
if (UnscaledLdOffset == UnscaledStOffset) {
|
|
uint32_t AndMaskEncoded = ((IsStoreXReg ? 1 : 0) << 12) // N
|
|
| ((Immr) << 6) // immr
|
|
| ((Imms) << 0) // imms
|
|
;
|
|
|
|
BitExtMI =
|
|
BuildMI(*LoadI->getParent(), LoadI, LoadI->getDebugLoc(),
|
|
TII->get(IsStoreXReg ? AArch64::ANDXri : AArch64::ANDWri),
|
|
DestReg)
|
|
.addReg(StRt)
|
|
.addImm(AndMaskEncoded);
|
|
} else {
|
|
BitExtMI =
|
|
BuildMI(*LoadI->getParent(), LoadI, LoadI->getDebugLoc(),
|
|
TII->get(IsStoreXReg ? AArch64::UBFMXri : AArch64::UBFMWri),
|
|
DestReg)
|
|
.addReg(StRt)
|
|
.addImm(Immr)
|
|
.addImm(Imms);
|
|
}
|
|
}
|
|
|
|
DEBUG(dbgs() << "Promoting load by replacing :\n ");
|
|
DEBUG(StoreI->print(dbgs()));
|
|
DEBUG(dbgs() << " ");
|
|
DEBUG(LoadI->print(dbgs()));
|
|
DEBUG(dbgs() << " with instructions:\n ");
|
|
DEBUG(StoreI->print(dbgs()));
|
|
DEBUG(dbgs() << " ");
|
|
DEBUG((BitExtMI)->print(dbgs()));
|
|
DEBUG(dbgs() << "\n");
|
|
|
|
// Erase the old instructions.
|
|
LoadI->eraseFromParent();
|
|
return NextI;
|
|
}
|
|
|
|
/// trackRegDefsUses - Remember what registers the specified instruction uses
|
|
/// and modifies.
|
|
static void trackRegDefsUses(const MachineInstr *MI, BitVector &ModifiedRegs,
|
|
BitVector &UsedRegs,
|
|
const TargetRegisterInfo *TRI) {
|
|
for (const MachineOperand &MO : MI->operands()) {
|
|
if (MO.isRegMask())
|
|
ModifiedRegs.setBitsNotInMask(MO.getRegMask());
|
|
|
|
if (!MO.isReg())
|
|
continue;
|
|
unsigned Reg = MO.getReg();
|
|
if (MO.isDef()) {
|
|
for (MCRegAliasIterator AI(Reg, TRI, true); AI.isValid(); ++AI)
|
|
ModifiedRegs.set(*AI);
|
|
} else {
|
|
assert(MO.isUse() && "Reg operand not a def and not a use?!?");
|
|
for (MCRegAliasIterator AI(Reg, TRI, true); AI.isValid(); ++AI)
|
|
UsedRegs.set(*AI);
|
|
}
|
|
}
|
|
}
|
|
|
|
static bool inBoundsForPair(bool IsUnscaled, int Offset, int OffsetStride) {
|
|
// Convert the byte-offset used by unscaled into an "element" offset used
|
|
// by the scaled pair load/store instructions.
|
|
if (IsUnscaled) {
|
|
// If the byte-offset isn't a multiple of the stride, there's no point
|
|
// trying to match it.
|
|
if (Offset % OffsetStride)
|
|
return false;
|
|
Offset /= OffsetStride;
|
|
}
|
|
return Offset <= 63 && Offset >= -64;
|
|
}
|
|
|
|
// Do alignment, specialized to power of 2 and for signed ints,
|
|
// avoiding having to do a C-style cast from uint_64t to int when
|
|
// using alignTo from include/llvm/Support/MathExtras.h.
|
|
// FIXME: Move this function to include/MathExtras.h?
|
|
static int alignTo(int Num, int PowOf2) {
|
|
return (Num + PowOf2 - 1) & ~(PowOf2 - 1);
|
|
}
|
|
|
|
static bool mayAlias(MachineInstr *MIa, MachineInstr *MIb,
|
|
const AArch64InstrInfo *TII) {
|
|
// One of the instructions must modify memory.
|
|
if (!MIa->mayStore() && !MIb->mayStore())
|
|
return false;
|
|
|
|
// Both instructions must be memory operations.
|
|
if (!MIa->mayLoadOrStore() && !MIb->mayLoadOrStore())
|
|
return false;
|
|
|
|
return !TII->areMemAccessesTriviallyDisjoint(MIa, MIb);
|
|
}
|
|
|
|
static bool mayAlias(MachineInstr *MIa,
|
|
SmallVectorImpl<MachineInstr *> &MemInsns,
|
|
const AArch64InstrInfo *TII) {
|
|
for (auto &MIb : MemInsns)
|
|
if (mayAlias(MIa, MIb, TII))
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
bool AArch64LoadStoreOpt::findMatchingStore(
|
|
MachineBasicBlock::iterator I, unsigned Limit,
|
|
MachineBasicBlock::iterator &StoreI) {
|
|
MachineBasicBlock::iterator E = I->getParent()->begin();
|
|
MachineBasicBlock::iterator MBBI = I;
|
|
MachineInstr *FirstMI = I;
|
|
unsigned BaseReg = getLdStBaseOp(FirstMI).getReg();
|
|
|
|
// Track which registers have been modified and used between the first insn
|
|
// and the second insn.
|
|
ModifiedRegs.reset();
|
|
UsedRegs.reset();
|
|
|
|
// FIXME: We miss the case where the matching store is the first instruction
|
|
// in the basic block.
|
|
for (unsigned Count = 0; MBBI != E && Count < Limit;) {
|
|
--MBBI;
|
|
MachineInstr *MI = MBBI;
|
|
// Skip DBG_VALUE instructions. Otherwise debug info can affect the
|
|
// optimization by changing how far we scan.
|
|
if (MI->isDebugValue())
|
|
continue;
|
|
// Now that we know this is a real instruction, count it.
|
|
++Count;
|
|
|
|
// If the load instruction reads directly from the address to which the
|
|
// store instruction writes and the stored value is not modified, we can
|
|
// promote the load. Since we do not handle stores with pre-/post-index,
|
|
// it's unnecessary to check if BaseReg is modified by the store itself.
|
|
if (MI->mayStore() && isMatchingStore(FirstMI, MI) &&
|
|
BaseReg == getLdStBaseOp(MI).getReg() &&
|
|
isLdOffsetInRangeOfSt(FirstMI, MI) &&
|
|
!ModifiedRegs[getLdStRegOp(MI).getReg()]) {
|
|
StoreI = MBBI;
|
|
return true;
|
|
}
|
|
|
|
if (MI->isCall())
|
|
return false;
|
|
|
|
// Update modified / uses register lists.
|
|
trackRegDefsUses(MI, ModifiedRegs, UsedRegs, TRI);
|
|
|
|
// Otherwise, if the base register is modified, we have no match, so
|
|
// return early.
|
|
if (ModifiedRegs[BaseReg])
|
|
return false;
|
|
|
|
// If we encounter a store aliased with the load, return early.
|
|
if (MI->mayStore() && mayAlias(FirstMI, MI, TII))
|
|
return false;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
|
|
static bool canMergeOpc(unsigned Opc, unsigned PairOpc, LdStPairFlags &Flags) {
|
|
// Opcodes match: nothing more to check.
|
|
if (Opc == PairOpc)
|
|
return true;
|
|
|
|
// Try to match a sign-extended load/store with a zero-extended load/store.
|
|
bool IsValidLdStrOpc, PairIsValidLdStrOpc;
|
|
unsigned NonSExtOpc = getMatchingNonSExtOpcode(Opc, &IsValidLdStrOpc);
|
|
assert(IsValidLdStrOpc &&
|
|
"Given Opc should be a Load or Store with an immediate");
|
|
// Opc will be the first instruction in the pair.
|
|
if (NonSExtOpc == getMatchingNonSExtOpcode(PairOpc, &PairIsValidLdStrOpc)) {
|
|
Flags.setSExtIdx(NonSExtOpc == (unsigned)Opc ? 1 : 0);
|
|
return true;
|
|
}
|
|
|
|
// FIXME: Can we also match a mixed sext/zext unscaled/scaled pair?
|
|
|
|
// If the second instruction isn't even a load/store, bail out.
|
|
if (!PairIsValidLdStrOpc)
|
|
return false;
|
|
|
|
// Try to match an unscaled load/store with a scaled load/store.
|
|
return isUnscaledLdSt(Opc) != isUnscaledLdSt(PairOpc) &&
|
|
getMatchingPairOpcode(Opc) == getMatchingPairOpcode(PairOpc);
|
|
}
|
|
/// findMatchingInsn - Scan the instructions looking for a load/store that can
|
|
/// be combined with the current instruction into a load/store pair.
|
|
MachineBasicBlock::iterator
|
|
AArch64LoadStoreOpt::findMatchingInsn(MachineBasicBlock::iterator I,
|
|
LdStPairFlags &Flags, unsigned Limit) {
|
|
MachineBasicBlock::iterator E = I->getParent()->end();
|
|
MachineBasicBlock::iterator MBBI = I;
|
|
MachineInstr *FirstMI = I;
|
|
++MBBI;
|
|
|
|
unsigned Opc = FirstMI->getOpcode();
|
|
bool MayLoad = FirstMI->mayLoad();
|
|
bool IsUnscaled = isUnscaledLdSt(FirstMI);
|
|
unsigned Reg = getLdStRegOp(FirstMI).getReg();
|
|
unsigned BaseReg = getLdStBaseOp(FirstMI).getReg();
|
|
int Offset = getLdStOffsetOp(FirstMI).getImm();
|
|
bool IsNarrowStore = isNarrowStore(Opc);
|
|
|
|
// For narrow stores, find only the case where the stored value is WZR.
|
|
if (IsNarrowStore && Reg != AArch64::WZR)
|
|
return E;
|
|
|
|
// Early exit if the first instruction modifies the base register.
|
|
// e.g., ldr x0, [x0]
|
|
if (FirstMI->modifiesRegister(BaseReg, TRI))
|
|
return E;
|
|
|
|
// Early exit if the offset if not possible to match. (6 bits of positive
|
|
// range, plus allow an extra one in case we find a later insn that matches
|
|
// with Offset-1)
|
|
int OffsetStride = IsUnscaled ? getMemScale(FirstMI) : 1;
|
|
if (!(isNarrowLoad(Opc) || IsNarrowStore) &&
|
|
!inBoundsForPair(IsUnscaled, Offset, OffsetStride))
|
|
return E;
|
|
|
|
// Track which registers have been modified and used between the first insn
|
|
// (inclusive) and the second insn.
|
|
ModifiedRegs.reset();
|
|
UsedRegs.reset();
|
|
|
|
// Remember any instructions that read/write memory between FirstMI and MI.
|
|
SmallVector<MachineInstr *, 4> MemInsns;
|
|
|
|
for (unsigned Count = 0; MBBI != E && Count < Limit; ++MBBI) {
|
|
MachineInstr *MI = MBBI;
|
|
// Skip DBG_VALUE instructions. Otherwise debug info can affect the
|
|
// optimization by changing how far we scan.
|
|
if (MI->isDebugValue())
|
|
continue;
|
|
|
|
// Now that we know this is a real instruction, count it.
|
|
++Count;
|
|
|
|
Flags.setSExtIdx(-1);
|
|
if (canMergeOpc(Opc, MI->getOpcode(), Flags) &&
|
|
getLdStOffsetOp(MI).isImm()) {
|
|
assert(MI->mayLoadOrStore() && "Expected memory operation.");
|
|
// If we've found another instruction with the same opcode, check to see
|
|
// if the base and offset are compatible with our starting instruction.
|
|
// These instructions all have scaled immediate operands, so we just
|
|
// check for +1/-1. Make sure to check the new instruction offset is
|
|
// actually an immediate and not a symbolic reference destined for
|
|
// a relocation.
|
|
//
|
|
// Pairwise instructions have a 7-bit signed offset field. Single insns
|
|
// have a 12-bit unsigned offset field. To be a valid combine, the
|
|
// final offset must be in range.
|
|
unsigned MIBaseReg = getLdStBaseOp(MI).getReg();
|
|
int MIOffset = getLdStOffsetOp(MI).getImm();
|
|
|
|
// We're trying to pair instructions that differ in how they are scaled.
|
|
// If FirstMI is scaled then scale the offset of MI accordingly.
|
|
// Otherwise, do the opposite (i.e., make MI's offset unscaled).
|
|
bool MIIsUnscaled = isUnscaledLdSt(MI);
|
|
if (IsUnscaled != MIIsUnscaled) {
|
|
int MemSize = getMemScale(MI);
|
|
if (MIIsUnscaled) {
|
|
// If the unscaled offset isn't a multiple of the MemSize, we can't
|
|
// pair the operations together: bail and keep looking.
|
|
if (MIOffset % MemSize)
|
|
continue;
|
|
MIOffset /= MemSize;
|
|
} else {
|
|
MIOffset *= MemSize;
|
|
}
|
|
}
|
|
|
|
if (BaseReg == MIBaseReg && ((Offset == MIOffset + OffsetStride) ||
|
|
(Offset + OffsetStride == MIOffset))) {
|
|
int MinOffset = Offset < MIOffset ? Offset : MIOffset;
|
|
// If this is a volatile load/store that otherwise matched, stop looking
|
|
// as something is going on that we don't have enough information to
|
|
// safely transform. Similarly, stop if we see a hint to avoid pairs.
|
|
if (MI->hasOrderedMemoryRef() || TII->isLdStPairSuppressed(MI))
|
|
return E;
|
|
// If the resultant immediate offset of merging these instructions
|
|
// is out of range for a pairwise instruction, bail and keep looking.
|
|
bool IsNarrowLoad = isNarrowLoad(MI->getOpcode());
|
|
if (!IsNarrowLoad &&
|
|
!inBoundsForPair(IsUnscaled, MinOffset, OffsetStride)) {
|
|
trackRegDefsUses(MI, ModifiedRegs, UsedRegs, TRI);
|
|
MemInsns.push_back(MI);
|
|
continue;
|
|
}
|
|
|
|
if (IsNarrowLoad || IsNarrowStore) {
|
|
// If the alignment requirements of the scaled wide load/store
|
|
// instruction can't express the offset of the scaled narrow
|
|
// input, bail and keep looking.
|
|
if (!IsUnscaled && alignTo(MinOffset, 2) != MinOffset) {
|
|
trackRegDefsUses(MI, ModifiedRegs, UsedRegs, TRI);
|
|
MemInsns.push_back(MI);
|
|
continue;
|
|
}
|
|
} else {
|
|
// If the alignment requirements of the paired (scaled) instruction
|
|
// can't express the offset of the unscaled input, bail and keep
|
|
// looking.
|
|
if (IsUnscaled && (alignTo(MinOffset, OffsetStride) != MinOffset)) {
|
|
trackRegDefsUses(MI, ModifiedRegs, UsedRegs, TRI);
|
|
MemInsns.push_back(MI);
|
|
continue;
|
|
}
|
|
}
|
|
// If the destination register of the loads is the same register, bail
|
|
// and keep looking. A load-pair instruction with both destination
|
|
// registers the same is UNPREDICTABLE and will result in an exception.
|
|
// For narrow stores, allow only when the stored value is the same
|
|
// (i.e., WZR).
|
|
if ((MayLoad && Reg == getLdStRegOp(MI).getReg()) ||
|
|
(IsNarrowStore && Reg != getLdStRegOp(MI).getReg())) {
|
|
trackRegDefsUses(MI, ModifiedRegs, UsedRegs, TRI);
|
|
MemInsns.push_back(MI);
|
|
continue;
|
|
}
|
|
|
|
// If the Rt of the second instruction was not modified or used between
|
|
// the two instructions and none of the instructions between the second
|
|
// and first alias with the second, we can combine the second into the
|
|
// first.
|
|
if (!ModifiedRegs[getLdStRegOp(MI).getReg()] &&
|
|
!(MI->mayLoad() && UsedRegs[getLdStRegOp(MI).getReg()]) &&
|
|
!mayAlias(MI, MemInsns, TII)) {
|
|
Flags.setMergeForward(false);
|
|
return MBBI;
|
|
}
|
|
|
|
// Likewise, if the Rt of the first instruction is not modified or used
|
|
// between the two instructions and none of the instructions between the
|
|
// first and the second alias with the first, we can combine the first
|
|
// into the second.
|
|
if (!ModifiedRegs[getLdStRegOp(FirstMI).getReg()] &&
|
|
!(MayLoad && UsedRegs[getLdStRegOp(FirstMI).getReg()]) &&
|
|
!mayAlias(FirstMI, MemInsns, TII)) {
|
|
Flags.setMergeForward(true);
|
|
return MBBI;
|
|
}
|
|
// Unable to combine these instructions due to interference in between.
|
|
// Keep looking.
|
|
}
|
|
}
|
|
|
|
// If the instruction wasn't a matching load or store. Stop searching if we
|
|
// encounter a call instruction that might modify memory.
|
|
if (MI->isCall())
|
|
return E;
|
|
|
|
// Update modified / uses register lists.
|
|
trackRegDefsUses(MI, ModifiedRegs, UsedRegs, TRI);
|
|
|
|
// Otherwise, if the base register is modified, we have no match, so
|
|
// return early.
|
|
if (ModifiedRegs[BaseReg])
|
|
return E;
|
|
|
|
// Update list of instructions that read/write memory.
|
|
if (MI->mayLoadOrStore())
|
|
MemInsns.push_back(MI);
|
|
}
|
|
return E;
|
|
}
|
|
|
|
MachineBasicBlock::iterator
|
|
AArch64LoadStoreOpt::mergeUpdateInsn(MachineBasicBlock::iterator I,
|
|
MachineBasicBlock::iterator Update,
|
|
bool IsPreIdx) {
|
|
assert((Update->getOpcode() == AArch64::ADDXri ||
|
|
Update->getOpcode() == AArch64::SUBXri) &&
|
|
"Unexpected base register update instruction to merge!");
|
|
MachineBasicBlock::iterator NextI = I;
|
|
// Return the instruction following the merged instruction, which is
|
|
// the instruction following our unmerged load. Unless that's the add/sub
|
|
// instruction we're merging, in which case it's the one after that.
|
|
if (++NextI == Update)
|
|
++NextI;
|
|
|
|
int Value = Update->getOperand(2).getImm();
|
|
assert(AArch64_AM::getShiftValue(Update->getOperand(3).getImm()) == 0 &&
|
|
"Can't merge 1 << 12 offset into pre-/post-indexed load / store");
|
|
if (Update->getOpcode() == AArch64::SUBXri)
|
|
Value = -Value;
|
|
|
|
unsigned NewOpc = IsPreIdx ? getPreIndexedOpcode(I->getOpcode())
|
|
: getPostIndexedOpcode(I->getOpcode());
|
|
MachineInstrBuilder MIB;
|
|
if (!isPairedLdSt(I)) {
|
|
// Non-paired instruction.
|
|
MIB = BuildMI(*I->getParent(), I, I->getDebugLoc(), TII->get(NewOpc))
|
|
.addOperand(getLdStRegOp(Update))
|
|
.addOperand(getLdStRegOp(I))
|
|
.addOperand(getLdStBaseOp(I))
|
|
.addImm(Value)
|
|
.setMemRefs(I->memoperands_begin(), I->memoperands_end());
|
|
} else {
|
|
// Paired instruction.
|
|
int Scale = getMemScale(I);
|
|
MIB = BuildMI(*I->getParent(), I, I->getDebugLoc(), TII->get(NewOpc))
|
|
.addOperand(getLdStRegOp(Update))
|
|
.addOperand(getLdStRegOp(I, 0))
|
|
.addOperand(getLdStRegOp(I, 1))
|
|
.addOperand(getLdStBaseOp(I))
|
|
.addImm(Value / Scale)
|
|
.setMemRefs(I->memoperands_begin(), I->memoperands_end());
|
|
}
|
|
(void)MIB;
|
|
|
|
if (IsPreIdx)
|
|
DEBUG(dbgs() << "Creating pre-indexed load/store.");
|
|
else
|
|
DEBUG(dbgs() << "Creating post-indexed load/store.");
|
|
DEBUG(dbgs() << " Replacing instructions:\n ");
|
|
DEBUG(I->print(dbgs()));
|
|
DEBUG(dbgs() << " ");
|
|
DEBUG(Update->print(dbgs()));
|
|
DEBUG(dbgs() << " with instruction:\n ");
|
|
DEBUG(((MachineInstr *)MIB)->print(dbgs()));
|
|
DEBUG(dbgs() << "\n");
|
|
|
|
// Erase the old instructions for the block.
|
|
I->eraseFromParent();
|
|
Update->eraseFromParent();
|
|
|
|
return NextI;
|
|
}
|
|
|
|
bool AArch64LoadStoreOpt::isMatchingUpdateInsn(MachineInstr *MemMI,
|
|
MachineInstr *MI,
|
|
unsigned BaseReg, int Offset) {
|
|
switch (MI->getOpcode()) {
|
|
default:
|
|
break;
|
|
case AArch64::SUBXri:
|
|
// Negate the offset for a SUB instruction.
|
|
Offset *= -1;
|
|
// FALLTHROUGH
|
|
case AArch64::ADDXri:
|
|
// Make sure it's a vanilla immediate operand, not a relocation or
|
|
// anything else we can't handle.
|
|
if (!MI->getOperand(2).isImm())
|
|
break;
|
|
// Watch out for 1 << 12 shifted value.
|
|
if (AArch64_AM::getShiftValue(MI->getOperand(3).getImm()))
|
|
break;
|
|
|
|
// The update instruction source and destination register must be the
|
|
// same as the load/store base register.
|
|
if (MI->getOperand(0).getReg() != BaseReg ||
|
|
MI->getOperand(1).getReg() != BaseReg)
|
|
break;
|
|
|
|
bool IsPairedInsn = isPairedLdSt(MemMI);
|
|
int UpdateOffset = MI->getOperand(2).getImm();
|
|
// For non-paired load/store instructions, the immediate must fit in a
|
|
// signed 9-bit integer.
|
|
if (!IsPairedInsn && (UpdateOffset > 255 || UpdateOffset < -256))
|
|
break;
|
|
|
|
// For paired load/store instructions, the immediate must be a multiple of
|
|
// the scaling factor. The scaled offset must also fit into a signed 7-bit
|
|
// integer.
|
|
if (IsPairedInsn) {
|
|
int Scale = getMemScale(MemMI);
|
|
if (UpdateOffset % Scale != 0)
|
|
break;
|
|
|
|
int ScaledOffset = UpdateOffset / Scale;
|
|
if (ScaledOffset > 64 || ScaledOffset < -64)
|
|
break;
|
|
}
|
|
|
|
// If we have a non-zero Offset, we check that it matches the amount
|
|
// we're adding to the register.
|
|
if (!Offset || Offset == MI->getOperand(2).getImm())
|
|
return true;
|
|
break;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
MachineBasicBlock::iterator AArch64LoadStoreOpt::findMatchingUpdateInsnForward(
|
|
MachineBasicBlock::iterator I, int UnscaledOffset, unsigned Limit) {
|
|
MachineBasicBlock::iterator E = I->getParent()->end();
|
|
MachineInstr *MemMI = I;
|
|
MachineBasicBlock::iterator MBBI = I;
|
|
|
|
unsigned BaseReg = getLdStBaseOp(MemMI).getReg();
|
|
int MIUnscaledOffset = getLdStOffsetOp(MemMI).getImm() * getMemScale(MemMI);
|
|
|
|
// Scan forward looking for post-index opportunities. Updating instructions
|
|
// can't be formed if the memory instruction doesn't have the offset we're
|
|
// looking for.
|
|
if (MIUnscaledOffset != UnscaledOffset)
|
|
return E;
|
|
|
|
// If the base register overlaps a destination register, we can't
|
|
// merge the update.
|
|
bool IsPairedInsn = isPairedLdSt(MemMI);
|
|
for (unsigned i = 0, e = IsPairedInsn ? 2 : 1; i != e; ++i) {
|
|
unsigned DestReg = getLdStRegOp(MemMI, i).getReg();
|
|
if (DestReg == BaseReg || TRI->isSubRegister(BaseReg, DestReg))
|
|
return E;
|
|
}
|
|
|
|
// Track which registers have been modified and used between the first insn
|
|
// (inclusive) and the second insn.
|
|
ModifiedRegs.reset();
|
|
UsedRegs.reset();
|
|
++MBBI;
|
|
for (unsigned Count = 0; MBBI != E && Count < Limit; ++MBBI) {
|
|
MachineInstr *MI = MBBI;
|
|
// Skip DBG_VALUE instructions.
|
|
if (MI->isDebugValue())
|
|
continue;
|
|
|
|
// Now that we know this is a real instruction, count it.
|
|
++Count;
|
|
|
|
// If we found a match, return it.
|
|
if (isMatchingUpdateInsn(I, MI, BaseReg, UnscaledOffset))
|
|
return MBBI;
|
|
|
|
// Update the status of what the instruction clobbered and used.
|
|
trackRegDefsUses(MI, ModifiedRegs, UsedRegs, TRI);
|
|
|
|
// Otherwise, if the base register is used or modified, we have no match, so
|
|
// return early.
|
|
if (ModifiedRegs[BaseReg] || UsedRegs[BaseReg])
|
|
return E;
|
|
}
|
|
return E;
|
|
}
|
|
|
|
MachineBasicBlock::iterator AArch64LoadStoreOpt::findMatchingUpdateInsnBackward(
|
|
MachineBasicBlock::iterator I, unsigned Limit) {
|
|
MachineBasicBlock::iterator B = I->getParent()->begin();
|
|
MachineBasicBlock::iterator E = I->getParent()->end();
|
|
MachineInstr *MemMI = I;
|
|
MachineBasicBlock::iterator MBBI = I;
|
|
|
|
unsigned BaseReg = getLdStBaseOp(MemMI).getReg();
|
|
int Offset = getLdStOffsetOp(MemMI).getImm();
|
|
|
|
// If the load/store is the first instruction in the block, there's obviously
|
|
// not any matching update. Ditto if the memory offset isn't zero.
|
|
if (MBBI == B || Offset != 0)
|
|
return E;
|
|
// If the base register overlaps a destination register, we can't
|
|
// merge the update.
|
|
bool IsPairedInsn = isPairedLdSt(MemMI);
|
|
for (unsigned i = 0, e = IsPairedInsn ? 2 : 1; i != e; ++i) {
|
|
unsigned DestReg = getLdStRegOp(MemMI, i).getReg();
|
|
if (DestReg == BaseReg || TRI->isSubRegister(BaseReg, DestReg))
|
|
return E;
|
|
}
|
|
|
|
// Track which registers have been modified and used between the first insn
|
|
// (inclusive) and the second insn.
|
|
ModifiedRegs.reset();
|
|
UsedRegs.reset();
|
|
--MBBI;
|
|
for (unsigned Count = 0; MBBI != B && Count < Limit; --MBBI) {
|
|
MachineInstr *MI = MBBI;
|
|
// Skip DBG_VALUE instructions.
|
|
if (MI->isDebugValue())
|
|
continue;
|
|
|
|
// Now that we know this is a real instruction, count it.
|
|
++Count;
|
|
|
|
// If we found a match, return it.
|
|
if (isMatchingUpdateInsn(I, MI, BaseReg, Offset))
|
|
return MBBI;
|
|
|
|
// Update the status of what the instruction clobbered and used.
|
|
trackRegDefsUses(MI, ModifiedRegs, UsedRegs, TRI);
|
|
|
|
// Otherwise, if the base register is used or modified, we have no match, so
|
|
// return early.
|
|
if (ModifiedRegs[BaseReg] || UsedRegs[BaseReg])
|
|
return E;
|
|
}
|
|
return E;
|
|
}
|
|
|
|
bool AArch64LoadStoreOpt::tryToPromoteLoadFromStore(
|
|
MachineBasicBlock::iterator &MBBI) {
|
|
MachineInstr *MI = MBBI;
|
|
// If this is a volatile load, don't mess with it.
|
|
if (MI->hasOrderedMemoryRef())
|
|
return false;
|
|
|
|
// Make sure this is a reg+imm.
|
|
// FIXME: It is possible to extend it to handle reg+reg cases.
|
|
if (!getLdStOffsetOp(MI).isImm())
|
|
return false;
|
|
|
|
// Look backward up to LdStLimit instructions.
|
|
MachineBasicBlock::iterator StoreI;
|
|
if (findMatchingStore(MBBI, LdStLimit, StoreI)) {
|
|
++NumLoadsFromStoresPromoted;
|
|
// Promote the load. Keeping the iterator straight is a
|
|
// pain, so we let the merge routine tell us what the next instruction
|
|
// is after it's done mucking about.
|
|
MBBI = promoteLoadFromStore(MBBI, StoreI);
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
bool AArch64LoadStoreOpt::tryToMergeLdStInst(
|
|
MachineBasicBlock::iterator &MBBI) {
|
|
MachineInstr *MI = MBBI;
|
|
MachineBasicBlock::iterator E = MI->getParent()->end();
|
|
// If this is a volatile load/store, don't mess with it.
|
|
if (MI->hasOrderedMemoryRef())
|
|
return false;
|
|
|
|
// Make sure this is a reg+imm (as opposed to an address reloc).
|
|
if (!getLdStOffsetOp(MI).isImm())
|
|
return false;
|
|
|
|
// Check if this load/store has a hint to avoid pair formation.
|
|
// MachineMemOperands hints are set by the AArch64StorePairSuppress pass.
|
|
if (TII->isLdStPairSuppressed(MI))
|
|
return false;
|
|
|
|
// Look ahead up to LdStLimit instructions for a pairable instruction.
|
|
LdStPairFlags Flags;
|
|
MachineBasicBlock::iterator Paired = findMatchingInsn(MBBI, Flags, LdStLimit);
|
|
if (Paired != E) {
|
|
if (isNarrowLoad(MI)) {
|
|
++NumNarrowLoadsPromoted;
|
|
} else if (isNarrowStore(MI)) {
|
|
++NumZeroStoresPromoted;
|
|
} else {
|
|
++NumPairCreated;
|
|
if (isUnscaledLdSt(MI))
|
|
++NumUnscaledPairCreated;
|
|
}
|
|
|
|
// Merge the loads into a pair. Keeping the iterator straight is a
|
|
// pain, so we let the merge routine tell us what the next instruction
|
|
// is after it's done mucking about.
|
|
MBBI = mergePairedInsns(MBBI, Paired, Flags);
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
bool AArch64LoadStoreOpt::optimizeBlock(MachineBasicBlock &MBB,
|
|
bool enableNarrowLdOpt) {
|
|
bool Modified = false;
|
|
// Four tranformations to do here:
|
|
// 1) Find loads that directly read from stores and promote them by
|
|
// replacing with mov instructions. If the store is wider than the load,
|
|
// the load will be replaced with a bitfield extract.
|
|
// e.g.,
|
|
// str w1, [x0, #4]
|
|
// ldrh w2, [x0, #6]
|
|
// ; becomes
|
|
// str w1, [x0, #4]
|
|
// lsr w2, w1, #16
|
|
for (MachineBasicBlock::iterator MBBI = MBB.begin(), E = MBB.end();
|
|
MBBI != E;) {
|
|
MachineInstr *MI = MBBI;
|
|
switch (MI->getOpcode()) {
|
|
default:
|
|
// Just move on to the next instruction.
|
|
++MBBI;
|
|
break;
|
|
// Scaled instructions.
|
|
case AArch64::LDRBBui:
|
|
case AArch64::LDRHHui:
|
|
case AArch64::LDRWui:
|
|
case AArch64::LDRXui:
|
|
// Unscaled instructions.
|
|
case AArch64::LDURBBi:
|
|
case AArch64::LDURHHi:
|
|
case AArch64::LDURWi:
|
|
case AArch64::LDURXi: {
|
|
if (tryToPromoteLoadFromStore(MBBI)) {
|
|
Modified = true;
|
|
break;
|
|
}
|
|
++MBBI;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
// 2) Find narrow loads that can be converted into a single wider load
|
|
// with bitfield extract instructions.
|
|
// e.g.,
|
|
// ldrh w0, [x2]
|
|
// ldrh w1, [x2, #2]
|
|
// ; becomes
|
|
// ldr w0, [x2]
|
|
// ubfx w1, w0, #16, #16
|
|
// and w0, w0, #ffff
|
|
for (MachineBasicBlock::iterator MBBI = MBB.begin(), E = MBB.end();
|
|
enableNarrowLdOpt && MBBI != E;) {
|
|
MachineInstr *MI = MBBI;
|
|
switch (MI->getOpcode()) {
|
|
default:
|
|
// Just move on to the next instruction.
|
|
++MBBI;
|
|
break;
|
|
// Scaled instructions.
|
|
case AArch64::LDRBBui:
|
|
case AArch64::LDRHHui:
|
|
case AArch64::LDRSBWui:
|
|
case AArch64::LDRSHWui:
|
|
case AArch64::STRBBui:
|
|
case AArch64::STRHHui:
|
|
// Unscaled instructions.
|
|
case AArch64::LDURBBi:
|
|
case AArch64::LDURHHi:
|
|
case AArch64::LDURSBWi:
|
|
case AArch64::LDURSHWi:
|
|
case AArch64::STURBBi:
|
|
case AArch64::STURHHi: {
|
|
if (tryToMergeLdStInst(MBBI)) {
|
|
Modified = true;
|
|
break;
|
|
}
|
|
++MBBI;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
// 3) Find loads and stores that can be merged into a single load or store
|
|
// pair instruction.
|
|
// e.g.,
|
|
// ldr x0, [x2]
|
|
// ldr x1, [x2, #8]
|
|
// ; becomes
|
|
// ldp x0, x1, [x2]
|
|
for (MachineBasicBlock::iterator MBBI = MBB.begin(), E = MBB.end();
|
|
MBBI != E;) {
|
|
MachineInstr *MI = MBBI;
|
|
switch (MI->getOpcode()) {
|
|
default:
|
|
// Just move on to the next instruction.
|
|
++MBBI;
|
|
break;
|
|
// Scaled instructions.
|
|
case AArch64::STRSui:
|
|
case AArch64::STRDui:
|
|
case AArch64::STRQui:
|
|
case AArch64::STRXui:
|
|
case AArch64::STRWui:
|
|
case AArch64::LDRSui:
|
|
case AArch64::LDRDui:
|
|
case AArch64::LDRQui:
|
|
case AArch64::LDRXui:
|
|
case AArch64::LDRWui:
|
|
case AArch64::LDRSWui:
|
|
// Unscaled instructions.
|
|
case AArch64::STURSi:
|
|
case AArch64::STURDi:
|
|
case AArch64::STURQi:
|
|
case AArch64::STURWi:
|
|
case AArch64::STURXi:
|
|
case AArch64::LDURSi:
|
|
case AArch64::LDURDi:
|
|
case AArch64::LDURQi:
|
|
case AArch64::LDURWi:
|
|
case AArch64::LDURXi:
|
|
case AArch64::LDURSWi: {
|
|
if (tryToMergeLdStInst(MBBI)) {
|
|
Modified = true;
|
|
break;
|
|
}
|
|
++MBBI;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
// 4) Find base register updates that can be merged into the load or store
|
|
// as a base-reg writeback.
|
|
// e.g.,
|
|
// ldr x0, [x2]
|
|
// add x2, x2, #4
|
|
// ; becomes
|
|
// ldr x0, [x2], #4
|
|
for (MachineBasicBlock::iterator MBBI = MBB.begin(), E = MBB.end();
|
|
MBBI != E;) {
|
|
MachineInstr *MI = MBBI;
|
|
// Do update merging. It's simpler to keep this separate from the above
|
|
// switchs, though not strictly necessary.
|
|
unsigned Opc = MI->getOpcode();
|
|
switch (Opc) {
|
|
default:
|
|
// Just move on to the next instruction.
|
|
++MBBI;
|
|
break;
|
|
// Scaled instructions.
|
|
case AArch64::STRSui:
|
|
case AArch64::STRDui:
|
|
case AArch64::STRQui:
|
|
case AArch64::STRXui:
|
|
case AArch64::STRWui:
|
|
case AArch64::STRHHui:
|
|
case AArch64::STRBBui:
|
|
case AArch64::LDRSui:
|
|
case AArch64::LDRDui:
|
|
case AArch64::LDRQui:
|
|
case AArch64::LDRXui:
|
|
case AArch64::LDRWui:
|
|
case AArch64::LDRHHui:
|
|
case AArch64::LDRBBui:
|
|
// Unscaled instructions.
|
|
case AArch64::STURSi:
|
|
case AArch64::STURDi:
|
|
case AArch64::STURQi:
|
|
case AArch64::STURWi:
|
|
case AArch64::STURXi:
|
|
case AArch64::LDURSi:
|
|
case AArch64::LDURDi:
|
|
case AArch64::LDURQi:
|
|
case AArch64::LDURWi:
|
|
case AArch64::LDURXi:
|
|
// Paired instructions.
|
|
case AArch64::LDPSi:
|
|
case AArch64::LDPSWi:
|
|
case AArch64::LDPDi:
|
|
case AArch64::LDPQi:
|
|
case AArch64::LDPWi:
|
|
case AArch64::LDPXi:
|
|
case AArch64::STPSi:
|
|
case AArch64::STPDi:
|
|
case AArch64::STPQi:
|
|
case AArch64::STPWi:
|
|
case AArch64::STPXi: {
|
|
// Make sure this is a reg+imm (as opposed to an address reloc).
|
|
if (!getLdStOffsetOp(MI).isImm()) {
|
|
++MBBI;
|
|
break;
|
|
}
|
|
// Look forward to try to form a post-index instruction. For example,
|
|
// ldr x0, [x20]
|
|
// add x20, x20, #32
|
|
// merged into:
|
|
// ldr x0, [x20], #32
|
|
MachineBasicBlock::iterator Update =
|
|
findMatchingUpdateInsnForward(MBBI, 0, UpdateLimit);
|
|
if (Update != E) {
|
|
// Merge the update into the ld/st.
|
|
MBBI = mergeUpdateInsn(MBBI, Update, /*IsPreIdx=*/false);
|
|
Modified = true;
|
|
++NumPostFolded;
|
|
break;
|
|
}
|
|
// Don't know how to handle pre/post-index versions, so move to the next
|
|
// instruction.
|
|
if (isUnscaledLdSt(Opc)) {
|
|
++MBBI;
|
|
break;
|
|
}
|
|
|
|
// Look back to try to find a pre-index instruction. For example,
|
|
// add x0, x0, #8
|
|
// ldr x1, [x0]
|
|
// merged into:
|
|
// ldr x1, [x0, #8]!
|
|
Update = findMatchingUpdateInsnBackward(MBBI, UpdateLimit);
|
|
if (Update != E) {
|
|
// Merge the update into the ld/st.
|
|
MBBI = mergeUpdateInsn(MBBI, Update, /*IsPreIdx=*/true);
|
|
Modified = true;
|
|
++NumPreFolded;
|
|
break;
|
|
}
|
|
// The immediate in the load/store is scaled by the size of the memory
|
|
// operation. The immediate in the add we're looking for,
|
|
// however, is not, so adjust here.
|
|
int UnscaledOffset = getLdStOffsetOp(MI).getImm() * getMemScale(MI);
|
|
|
|
// Look forward to try to find a post-index instruction. For example,
|
|
// ldr x1, [x0, #64]
|
|
// add x0, x0, #64
|
|
// merged into:
|
|
// ldr x1, [x0, #64]!
|
|
Update = findMatchingUpdateInsnForward(MBBI, UnscaledOffset, UpdateLimit);
|
|
if (Update != E) {
|
|
// Merge the update into the ld/st.
|
|
MBBI = mergeUpdateInsn(MBBI, Update, /*IsPreIdx=*/true);
|
|
Modified = true;
|
|
++NumPreFolded;
|
|
break;
|
|
}
|
|
|
|
// Nothing found. Just move to the next instruction.
|
|
++MBBI;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
return Modified;
|
|
}
|
|
|
|
bool AArch64LoadStoreOpt::enableNarrowLdMerge(MachineFunction &Fn) {
|
|
bool ProfitableArch = Subtarget->isCortexA57();
|
|
// FIXME: The benefit from converting narrow loads into a wider load could be
|
|
// microarchitectural as it assumes that a single load with two bitfield
|
|
// extracts is cheaper than two narrow loads. Currently, this conversion is
|
|
// enabled only in cortex-a57 on which performance benefits were verified.
|
|
return ProfitableArch && !Subtarget->requiresStrictAlign();
|
|
}
|
|
|
|
bool AArch64LoadStoreOpt::runOnMachineFunction(MachineFunction &Fn) {
|
|
Subtarget = &static_cast<const AArch64Subtarget &>(Fn.getSubtarget());
|
|
TII = static_cast<const AArch64InstrInfo *>(Subtarget->getInstrInfo());
|
|
TRI = Subtarget->getRegisterInfo();
|
|
|
|
// Resize the modified and used register bitfield trackers. We do this once
|
|
// per function and then clear the bitfield each time we optimize a load or
|
|
// store.
|
|
ModifiedRegs.resize(TRI->getNumRegs());
|
|
UsedRegs.resize(TRI->getNumRegs());
|
|
|
|
bool Modified = false;
|
|
bool enableNarrowLdOpt = enableNarrowLdMerge(Fn);
|
|
for (auto &MBB : Fn)
|
|
Modified |= optimizeBlock(MBB, enableNarrowLdOpt);
|
|
|
|
return Modified;
|
|
}
|
|
|
|
// FIXME: Do we need/want a pre-alloc pass like ARM has to try to keep
|
|
// loads and stores near one another?
|
|
|
|
/// createAArch64LoadStoreOptimizationPass - returns an instance of the
|
|
/// load / store optimization pass.
|
|
FunctionPass *llvm::createAArch64LoadStoreOptimizationPass() {
|
|
return new AArch64LoadStoreOpt();
|
|
}
|