forked from OSchip/llvm-project
918 lines
34 KiB
C++
918 lines
34 KiB
C++
//===------ PPCLoopInstrFormPrep.cpp - Loop Instr Form Prep Pass ----------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements a pass to prepare loops for ppc preferred addressing
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// modes, leveraging different instruction form. (eg: DS/DQ form, D/DS form with
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// update)
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// Additional PHIs are created for loop induction variables used by load/store
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// instructions so that preferred addressing modes can be used.
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//
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// 1: DS/DQ form preparation, prepare the load/store instructions so that they
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// can satisfy the DS/DQ form displacement requirements.
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// Generically, this means transforming loops like this:
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// for (int i = 0; i < n; ++i) {
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// unsigned long x1 = *(unsigned long *)(p + i + 5);
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// unsigned long x2 = *(unsigned long *)(p + i + 9);
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// }
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//
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// to look like this:
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//
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// unsigned NewP = p + 5;
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// for (int i = 0; i < n; ++i) {
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// unsigned long x1 = *(unsigned long *)(i + NewP);
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// unsigned long x2 = *(unsigned long *)(i + NewP + 4);
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// }
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//
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// 2: D/DS form with update preparation, prepare the load/store instructions so
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// that we can use update form to do pre-increment.
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// Generically, this means transforming loops like this:
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// for (int i = 0; i < n; ++i)
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// array[i] = c;
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//
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// to look like this:
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//
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// T *p = array[-1];
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// for (int i = 0; i < n; ++i)
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// *++p = c;
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "ppc-loop-instr-form-prep"
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#include "PPC.h"
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#include "PPCSubtarget.h"
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#include "PPCTargetMachine.h"
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#include "llvm/ADT/DepthFirstIterator.h"
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#include "llvm/ADT/SmallPtrSet.h"
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#include "llvm/ADT/SmallSet.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/LoopInfo.h"
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#include "llvm/Analysis/ScalarEvolution.h"
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#include "llvm/Analysis/ScalarEvolutionExpressions.h"
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#include "llvm/IR/BasicBlock.h"
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#include "llvm/IR/CFG.h"
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#include "llvm/IR/Dominators.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/IntrinsicsPowerPC.h"
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#include "llvm/IR/Module.h"
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#include "llvm/IR/Type.h"
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#include "llvm/IR/Value.h"
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#include "llvm/InitializePasses.h"
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#include "llvm/Pass.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/Debug.h"
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#include "llvm/Transforms/Scalar.h"
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#include "llvm/Transforms/Utils.h"
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#include "llvm/Transforms/Utils/BasicBlockUtils.h"
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#include "llvm/Transforms/Utils/Local.h"
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#include "llvm/Transforms/Utils/LoopUtils.h"
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#include "llvm/Transforms/Utils/ScalarEvolutionExpander.h"
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#include <cassert>
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#include <iterator>
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#include <utility>
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using namespace llvm;
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// By default, we limit this to creating 16 common bases out of loops per
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// function. 16 is a little over half of the allocatable register set.
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static cl::opt<unsigned> MaxVarsPrep("ppc-formprep-max-vars",
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cl::Hidden, cl::init(16),
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cl::desc("Potential common base number threshold per function for PPC loop "
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"prep"));
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static cl::opt<bool> PreferUpdateForm("ppc-formprep-prefer-update",
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cl::init(true), cl::Hidden,
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cl::desc("prefer update form when ds form is also a update form"));
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// Sum of following 3 per loop thresholds for all loops can not be larger
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// than MaxVarsPrep.
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// By default, we limit this to creating 9 PHIs for one loop.
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// 9 and 3 for each kind prep are exterimental values on Power9.
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static cl::opt<unsigned> MaxVarsUpdateForm("ppc-preinc-prep-max-vars",
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cl::Hidden, cl::init(3),
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cl::desc("Potential PHI threshold per loop for PPC loop prep of update "
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"form"));
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static cl::opt<unsigned> MaxVarsDSForm("ppc-dsprep-max-vars",
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cl::Hidden, cl::init(3),
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cl::desc("Potential PHI threshold per loop for PPC loop prep of DS form"));
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static cl::opt<unsigned> MaxVarsDQForm("ppc-dqprep-max-vars",
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cl::Hidden, cl::init(3),
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cl::desc("Potential PHI threshold per loop for PPC loop prep of DQ form"));
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// If would not be profitable if the common base has only one load/store, ISEL
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// should already be able to choose best load/store form based on offset for
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// single load/store. Set minimal profitable value default to 2 and make it as
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// an option.
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static cl::opt<unsigned> DispFormPrepMinThreshold("ppc-dispprep-min-threshold",
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cl::Hidden, cl::init(2),
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cl::desc("Minimal common base load/store instructions triggering DS/DQ form "
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"preparation"));
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STATISTIC(PHINodeAlreadyExistsUpdate, "PHI node already in pre-increment form");
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STATISTIC(PHINodeAlreadyExistsDS, "PHI node already in DS form");
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STATISTIC(PHINodeAlreadyExistsDQ, "PHI node already in DQ form");
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STATISTIC(DSFormChainRewritten, "Num of DS form chain rewritten");
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STATISTIC(DQFormChainRewritten, "Num of DQ form chain rewritten");
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STATISTIC(UpdFormChainRewritten, "Num of update form chain rewritten");
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namespace {
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struct BucketElement {
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BucketElement(const SCEVConstant *O, Instruction *I) : Offset(O), Instr(I) {}
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BucketElement(Instruction *I) : Offset(nullptr), Instr(I) {}
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const SCEVConstant *Offset;
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Instruction *Instr;
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};
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struct Bucket {
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Bucket(const SCEV *B, Instruction *I) : BaseSCEV(B),
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Elements(1, BucketElement(I)) {}
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const SCEV *BaseSCEV;
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SmallVector<BucketElement, 16> Elements;
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};
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// "UpdateForm" is not a real PPC instruction form, it stands for dform
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// load/store with update like ldu/stdu, or Prefetch intrinsic.
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// For DS form instructions, their displacements must be multiple of 4.
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// For DQ form instructions, their displacements must be multiple of 16.
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enum InstrForm { UpdateForm = 1, DSForm = 4, DQForm = 16 };
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class PPCLoopInstrFormPrep : public FunctionPass {
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public:
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static char ID; // Pass ID, replacement for typeid
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PPCLoopInstrFormPrep() : FunctionPass(ID) {
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initializePPCLoopInstrFormPrepPass(*PassRegistry::getPassRegistry());
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}
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PPCLoopInstrFormPrep(PPCTargetMachine &TM) : FunctionPass(ID), TM(&TM) {
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initializePPCLoopInstrFormPrepPass(*PassRegistry::getPassRegistry());
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}
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void getAnalysisUsage(AnalysisUsage &AU) const override {
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AU.addPreserved<DominatorTreeWrapperPass>();
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AU.addRequired<LoopInfoWrapperPass>();
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AU.addPreserved<LoopInfoWrapperPass>();
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AU.addRequired<ScalarEvolutionWrapperPass>();
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}
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bool runOnFunction(Function &F) override;
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private:
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PPCTargetMachine *TM = nullptr;
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const PPCSubtarget *ST;
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DominatorTree *DT;
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LoopInfo *LI;
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ScalarEvolution *SE;
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bool PreserveLCSSA;
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/// Successful preparation number for Update/DS/DQ form in all inner most
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/// loops. One successful preparation will put one common base out of loop,
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/// this may leads to register presure like LICM does.
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/// Make sure total preparation number can be controlled by option.
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unsigned SuccPrepCount;
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bool runOnLoop(Loop *L);
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/// Check if required PHI node is already exist in Loop \p L.
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bool alreadyPrepared(Loop *L, Instruction* MemI,
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const SCEV *BasePtrStartSCEV,
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const SCEVConstant *BasePtrIncSCEV,
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InstrForm Form);
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/// Collect condition matched(\p isValidCandidate() returns true)
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/// candidates in Loop \p L.
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SmallVector<Bucket, 16>
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collectCandidates(Loop *L,
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std::function<bool(const Instruction *, const Value *)>
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isValidCandidate,
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unsigned MaxCandidateNum);
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/// Add a candidate to candidates \p Buckets.
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void addOneCandidate(Instruction *MemI, const SCEV *LSCEV,
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SmallVector<Bucket, 16> &Buckets,
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unsigned MaxCandidateNum);
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/// Prepare all candidates in \p Buckets for update form.
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bool updateFormPrep(Loop *L, SmallVector<Bucket, 16> &Buckets);
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/// Prepare all candidates in \p Buckets for displacement form, now for
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/// ds/dq.
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bool dispFormPrep(Loop *L, SmallVector<Bucket, 16> &Buckets,
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InstrForm Form);
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/// Prepare for one chain \p BucketChain, find the best base element and
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/// update all other elements in \p BucketChain accordingly.
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/// \p Form is used to find the best base element.
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/// If success, best base element must be stored as the first element of
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/// \p BucketChain.
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/// Return false if no base element found, otherwise return true.
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bool prepareBaseForDispFormChain(Bucket &BucketChain,
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InstrForm Form);
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/// Prepare for one chain \p BucketChain, find the best base element and
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/// update all other elements in \p BucketChain accordingly.
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/// If success, best base element must be stored as the first element of
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/// \p BucketChain.
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/// Return false if no base element found, otherwise return true.
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bool prepareBaseForUpdateFormChain(Bucket &BucketChain);
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/// Rewrite load/store instructions in \p BucketChain according to
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/// preparation.
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bool rewriteLoadStores(Loop *L, Bucket &BucketChain,
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SmallSet<BasicBlock *, 16> &BBChanged,
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InstrForm Form);
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};
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} // end anonymous namespace
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char PPCLoopInstrFormPrep::ID = 0;
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static const char *name = "Prepare loop for ppc preferred instruction forms";
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INITIALIZE_PASS_BEGIN(PPCLoopInstrFormPrep, DEBUG_TYPE, name, false, false)
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INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)
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INITIALIZE_PASS_DEPENDENCY(ScalarEvolutionWrapperPass)
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INITIALIZE_PASS_END(PPCLoopInstrFormPrep, DEBUG_TYPE, name, false, false)
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static constexpr StringRef PHINodeNameSuffix = ".phi";
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static constexpr StringRef CastNodeNameSuffix = ".cast";
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static constexpr StringRef GEPNodeIncNameSuffix = ".inc";
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static constexpr StringRef GEPNodeOffNameSuffix = ".off";
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FunctionPass *llvm::createPPCLoopInstrFormPrepPass(PPCTargetMachine &TM) {
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return new PPCLoopInstrFormPrep(TM);
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}
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static bool IsPtrInBounds(Value *BasePtr) {
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Value *StrippedBasePtr = BasePtr;
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while (BitCastInst *BC = dyn_cast<BitCastInst>(StrippedBasePtr))
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StrippedBasePtr = BC->getOperand(0);
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if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(StrippedBasePtr))
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return GEP->isInBounds();
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return false;
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}
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static std::string getInstrName(const Value *I, StringRef Suffix) {
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assert(I && "Invalid paramater!");
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if (I->hasName())
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return (I->getName() + Suffix).str();
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else
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return "";
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}
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static Value *GetPointerOperand(Value *MemI) {
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if (LoadInst *LMemI = dyn_cast<LoadInst>(MemI)) {
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return LMemI->getPointerOperand();
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} else if (StoreInst *SMemI = dyn_cast<StoreInst>(MemI)) {
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return SMemI->getPointerOperand();
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} else if (IntrinsicInst *IMemI = dyn_cast<IntrinsicInst>(MemI)) {
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if (IMemI->getIntrinsicID() == Intrinsic::prefetch ||
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IMemI->getIntrinsicID() == Intrinsic::ppc_mma_lxvp)
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return IMemI->getArgOperand(0);
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if (IMemI->getIntrinsicID() == Intrinsic::ppc_mma_stxvp)
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return IMemI->getArgOperand(1);
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}
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return nullptr;
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}
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bool PPCLoopInstrFormPrep::runOnFunction(Function &F) {
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if (skipFunction(F))
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return false;
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LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
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SE = &getAnalysis<ScalarEvolutionWrapperPass>().getSE();
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auto *DTWP = getAnalysisIfAvailable<DominatorTreeWrapperPass>();
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DT = DTWP ? &DTWP->getDomTree() : nullptr;
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PreserveLCSSA = mustPreserveAnalysisID(LCSSAID);
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ST = TM ? TM->getSubtargetImpl(F) : nullptr;
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SuccPrepCount = 0;
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bool MadeChange = false;
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for (auto I = LI->begin(), IE = LI->end(); I != IE; ++I)
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for (auto L = df_begin(*I), LE = df_end(*I); L != LE; ++L)
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MadeChange |= runOnLoop(*L);
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return MadeChange;
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}
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void PPCLoopInstrFormPrep::addOneCandidate(Instruction *MemI, const SCEV *LSCEV,
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SmallVector<Bucket, 16> &Buckets,
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unsigned MaxCandidateNum) {
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assert((MemI && GetPointerOperand(MemI)) &&
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"Candidate should be a memory instruction.");
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assert(LSCEV && "Invalid SCEV for Ptr value.");
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bool FoundBucket = false;
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for (auto &B : Buckets) {
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const SCEV *Diff = SE->getMinusSCEV(LSCEV, B.BaseSCEV);
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if (const auto *CDiff = dyn_cast<SCEVConstant>(Diff)) {
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B.Elements.push_back(BucketElement(CDiff, MemI));
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FoundBucket = true;
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break;
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}
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}
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if (!FoundBucket) {
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if (Buckets.size() == MaxCandidateNum)
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return;
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Buckets.push_back(Bucket(LSCEV, MemI));
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}
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}
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SmallVector<Bucket, 16> PPCLoopInstrFormPrep::collectCandidates(
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Loop *L,
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std::function<bool(const Instruction *, const Value *)> isValidCandidate,
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unsigned MaxCandidateNum) {
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SmallVector<Bucket, 16> Buckets;
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for (const auto &BB : L->blocks())
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for (auto &J : *BB) {
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Value *PtrValue;
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Instruction *MemI;
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if (LoadInst *LMemI = dyn_cast<LoadInst>(&J)) {
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MemI = LMemI;
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PtrValue = LMemI->getPointerOperand();
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} else if (StoreInst *SMemI = dyn_cast<StoreInst>(&J)) {
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MemI = SMemI;
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PtrValue = SMemI->getPointerOperand();
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} else if (IntrinsicInst *IMemI = dyn_cast<IntrinsicInst>(&J)) {
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if (IMemI->getIntrinsicID() == Intrinsic::prefetch ||
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IMemI->getIntrinsicID() == Intrinsic::ppc_mma_lxvp) {
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MemI = IMemI;
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PtrValue = IMemI->getArgOperand(0);
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} else if (IMemI->getIntrinsicID() == Intrinsic::ppc_mma_stxvp) {
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MemI = IMemI;
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PtrValue = IMemI->getArgOperand(1);
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} else continue;
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} else continue;
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unsigned PtrAddrSpace = PtrValue->getType()->getPointerAddressSpace();
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if (PtrAddrSpace)
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continue;
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if (L->isLoopInvariant(PtrValue))
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continue;
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const SCEV *LSCEV = SE->getSCEVAtScope(PtrValue, L);
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const SCEVAddRecExpr *LARSCEV = dyn_cast<SCEVAddRecExpr>(LSCEV);
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if (!LARSCEV || LARSCEV->getLoop() != L)
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continue;
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if (isValidCandidate(&J, PtrValue))
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addOneCandidate(MemI, LSCEV, Buckets, MaxCandidateNum);
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}
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return Buckets;
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}
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bool PPCLoopInstrFormPrep::prepareBaseForDispFormChain(Bucket &BucketChain,
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InstrForm Form) {
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// RemainderOffsetInfo details:
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// key: value of (Offset urem DispConstraint). For DSForm, it can
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// be [0, 4).
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// first of pair: the index of first BucketElement whose remainder is equal
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// to key. For key 0, this value must be 0.
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// second of pair: number of load/stores with the same remainder.
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DenseMap<unsigned, std::pair<unsigned, unsigned>> RemainderOffsetInfo;
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for (unsigned j = 0, je = BucketChain.Elements.size(); j != je; ++j) {
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if (!BucketChain.Elements[j].Offset)
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RemainderOffsetInfo[0] = std::make_pair(0, 1);
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else {
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unsigned Remainder =
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BucketChain.Elements[j].Offset->getAPInt().urem(Form);
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if (RemainderOffsetInfo.find(Remainder) == RemainderOffsetInfo.end())
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RemainderOffsetInfo[Remainder] = std::make_pair(j, 1);
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else
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RemainderOffsetInfo[Remainder].second++;
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}
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}
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// Currently we choose the most profitable base as the one which has the max
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// number of load/store with same remainder.
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// FIXME: adjust the base selection strategy according to load/store offset
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// distribution.
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// For example, if we have one candidate chain for DS form preparation, which
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// contains following load/stores with different remainders:
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// 1: 10 load/store whose remainder is 1;
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// 2: 9 load/store whose remainder is 2;
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// 3: 1 for remainder 3 and 0 for remainder 0;
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// Now we will choose the first load/store whose remainder is 1 as base and
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// adjust all other load/stores according to new base, so we will get 10 DS
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// form and 10 X form.
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// But we should be more clever, for this case we could use two bases, one for
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// remainder 1 and the other for remainder 2, thus we could get 19 DS form and 1
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// X form.
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unsigned MaxCountRemainder = 0;
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for (unsigned j = 0; j < (unsigned)Form; j++)
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if ((RemainderOffsetInfo.find(j) != RemainderOffsetInfo.end()) &&
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RemainderOffsetInfo[j].second >
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RemainderOffsetInfo[MaxCountRemainder].second)
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MaxCountRemainder = j;
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// Abort when there are too few insts with common base.
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if (RemainderOffsetInfo[MaxCountRemainder].second < DispFormPrepMinThreshold)
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return false;
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// If the first value is most profitable, no needed to adjust BucketChain
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// elements as they are substracted the first value when collecting.
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if (MaxCountRemainder == 0)
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return true;
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// Adjust load/store to the new chosen base.
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const SCEV *Offset =
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BucketChain.Elements[RemainderOffsetInfo[MaxCountRemainder].first].Offset;
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BucketChain.BaseSCEV = SE->getAddExpr(BucketChain.BaseSCEV, Offset);
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for (auto &E : BucketChain.Elements) {
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if (E.Offset)
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E.Offset = cast<SCEVConstant>(SE->getMinusSCEV(E.Offset, Offset));
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else
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E.Offset = cast<SCEVConstant>(SE->getNegativeSCEV(Offset));
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}
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std::swap(BucketChain.Elements[RemainderOffsetInfo[MaxCountRemainder].first],
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BucketChain.Elements[0]);
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return true;
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}
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// FIXME: implement a more clever base choosing policy.
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// Currently we always choose an exist load/store offset. This maybe lead to
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// suboptimal code sequences. For example, for one DS chain with offsets
|
|
// {-32769, 2003, 2007, 2011}, we choose -32769 as base offset, and left disp
|
|
// for load/stores are {0, 34772, 34776, 34780}. Though each offset now is a
|
|
// multipler of 4, it cannot be represented by sint16.
|
|
bool PPCLoopInstrFormPrep::prepareBaseForUpdateFormChain(Bucket &BucketChain) {
|
|
// We have a choice now of which instruction's memory operand we use as the
|
|
// base for the generated PHI. Always picking the first instruction in each
|
|
// bucket does not work well, specifically because that instruction might
|
|
// be a prefetch (and there are no pre-increment dcbt variants). Otherwise,
|
|
// the choice is somewhat arbitrary, because the backend will happily
|
|
// generate direct offsets from both the pre-incremented and
|
|
// post-incremented pointer values. Thus, we'll pick the first non-prefetch
|
|
// instruction in each bucket, and adjust the recurrence and other offsets
|
|
// accordingly.
|
|
for (int j = 0, je = BucketChain.Elements.size(); j != je; ++j) {
|
|
if (auto *II = dyn_cast<IntrinsicInst>(BucketChain.Elements[j].Instr))
|
|
if (II->getIntrinsicID() == Intrinsic::prefetch)
|
|
continue;
|
|
|
|
// If we'd otherwise pick the first element anyway, there's nothing to do.
|
|
if (j == 0)
|
|
break;
|
|
|
|
// If our chosen element has no offset from the base pointer, there's
|
|
// nothing to do.
|
|
if (!BucketChain.Elements[j].Offset ||
|
|
BucketChain.Elements[j].Offset->isZero())
|
|
break;
|
|
|
|
const SCEV *Offset = BucketChain.Elements[j].Offset;
|
|
BucketChain.BaseSCEV = SE->getAddExpr(BucketChain.BaseSCEV, Offset);
|
|
for (auto &E : BucketChain.Elements) {
|
|
if (E.Offset)
|
|
E.Offset = cast<SCEVConstant>(SE->getMinusSCEV(E.Offset, Offset));
|
|
else
|
|
E.Offset = cast<SCEVConstant>(SE->getNegativeSCEV(Offset));
|
|
}
|
|
|
|
std::swap(BucketChain.Elements[j], BucketChain.Elements[0]);
|
|
break;
|
|
}
|
|
return true;
|
|
}
|
|
|
|
bool PPCLoopInstrFormPrep::rewriteLoadStores(Loop *L, Bucket &BucketChain,
|
|
SmallSet<BasicBlock *, 16> &BBChanged,
|
|
InstrForm Form) {
|
|
bool MadeChange = false;
|
|
const SCEVAddRecExpr *BasePtrSCEV =
|
|
cast<SCEVAddRecExpr>(BucketChain.BaseSCEV);
|
|
if (!BasePtrSCEV->isAffine())
|
|
return MadeChange;
|
|
|
|
LLVM_DEBUG(dbgs() << "PIP: Transforming: " << *BasePtrSCEV << "\n");
|
|
|
|
assert(BasePtrSCEV->getLoop() == L && "AddRec for the wrong loop?");
|
|
|
|
// The instruction corresponding to the Bucket's BaseSCEV must be the first
|
|
// in the vector of elements.
|
|
Instruction *MemI = BucketChain.Elements.begin()->Instr;
|
|
Value *BasePtr = GetPointerOperand(MemI);
|
|
assert(BasePtr && "No pointer operand");
|
|
|
|
Type *I8Ty = Type::getInt8Ty(MemI->getParent()->getContext());
|
|
Type *I8PtrTy = Type::getInt8PtrTy(MemI->getParent()->getContext(),
|
|
BasePtr->getType()->getPointerAddressSpace());
|
|
|
|
if (!SE->isLoopInvariant(BasePtrSCEV->getStart(), L))
|
|
return MadeChange;
|
|
|
|
const SCEVConstant *BasePtrIncSCEV =
|
|
dyn_cast<SCEVConstant>(BasePtrSCEV->getStepRecurrence(*SE));
|
|
if (!BasePtrIncSCEV)
|
|
return MadeChange;
|
|
|
|
// For some DS form load/store instructions, it can also be an update form,
|
|
// if the stride is a multipler of 4. Use update form if prefer it.
|
|
bool CanPreInc = (Form == UpdateForm ||
|
|
((Form == DSForm) && !BasePtrIncSCEV->getAPInt().urem(4) &&
|
|
PreferUpdateForm));
|
|
const SCEV *BasePtrStartSCEV = nullptr;
|
|
if (CanPreInc)
|
|
BasePtrStartSCEV =
|
|
SE->getMinusSCEV(BasePtrSCEV->getStart(), BasePtrIncSCEV);
|
|
else
|
|
BasePtrStartSCEV = BasePtrSCEV->getStart();
|
|
|
|
if (!isSafeToExpand(BasePtrStartSCEV, *SE))
|
|
return MadeChange;
|
|
|
|
if (alreadyPrepared(L, MemI, BasePtrStartSCEV, BasePtrIncSCEV, Form))
|
|
return MadeChange;
|
|
|
|
LLVM_DEBUG(dbgs() << "PIP: New start is: " << *BasePtrStartSCEV << "\n");
|
|
|
|
BasicBlock *Header = L->getHeader();
|
|
unsigned HeaderLoopPredCount = pred_size(Header);
|
|
BasicBlock *LoopPredecessor = L->getLoopPredecessor();
|
|
|
|
PHINode *NewPHI =
|
|
PHINode::Create(I8PtrTy, HeaderLoopPredCount,
|
|
getInstrName(MemI, PHINodeNameSuffix),
|
|
Header->getFirstNonPHI());
|
|
|
|
SCEVExpander SCEVE(*SE, Header->getModule()->getDataLayout(), "pistart");
|
|
Value *BasePtrStart = SCEVE.expandCodeFor(BasePtrStartSCEV, I8PtrTy,
|
|
LoopPredecessor->getTerminator());
|
|
|
|
// Note that LoopPredecessor might occur in the predecessor list multiple
|
|
// times, and we need to add it the right number of times.
|
|
for (auto PI : predecessors(Header)) {
|
|
if (PI != LoopPredecessor)
|
|
continue;
|
|
|
|
NewPHI->addIncoming(BasePtrStart, LoopPredecessor);
|
|
}
|
|
|
|
Instruction *PtrInc = nullptr;
|
|
Instruction *NewBasePtr = nullptr;
|
|
if (CanPreInc) {
|
|
Instruction *InsPoint = &*Header->getFirstInsertionPt();
|
|
PtrInc = GetElementPtrInst::Create(
|
|
I8Ty, NewPHI, BasePtrIncSCEV->getValue(),
|
|
getInstrName(MemI, GEPNodeIncNameSuffix), InsPoint);
|
|
cast<GetElementPtrInst>(PtrInc)->setIsInBounds(IsPtrInBounds(BasePtr));
|
|
for (auto PI : predecessors(Header)) {
|
|
if (PI == LoopPredecessor)
|
|
continue;
|
|
|
|
NewPHI->addIncoming(PtrInc, PI);
|
|
}
|
|
if (PtrInc->getType() != BasePtr->getType())
|
|
NewBasePtr = new BitCastInst(
|
|
PtrInc, BasePtr->getType(),
|
|
getInstrName(PtrInc, CastNodeNameSuffix), InsPoint);
|
|
else
|
|
NewBasePtr = PtrInc;
|
|
} else {
|
|
// Note that LoopPredecessor might occur in the predecessor list multiple
|
|
// times, and we need to make sure no more incoming value for them in PHI.
|
|
for (auto PI : predecessors(Header)) {
|
|
if (PI == LoopPredecessor)
|
|
continue;
|
|
|
|
// For the latch predecessor, we need to insert a GEP just before the
|
|
// terminator to increase the address.
|
|
BasicBlock *BB = PI;
|
|
Instruction *InsPoint = BB->getTerminator();
|
|
PtrInc = GetElementPtrInst::Create(
|
|
I8Ty, NewPHI, BasePtrIncSCEV->getValue(),
|
|
getInstrName(MemI, GEPNodeIncNameSuffix), InsPoint);
|
|
|
|
cast<GetElementPtrInst>(PtrInc)->setIsInBounds(IsPtrInBounds(BasePtr));
|
|
|
|
NewPHI->addIncoming(PtrInc, PI);
|
|
}
|
|
PtrInc = NewPHI;
|
|
if (NewPHI->getType() != BasePtr->getType())
|
|
NewBasePtr =
|
|
new BitCastInst(NewPHI, BasePtr->getType(),
|
|
getInstrName(NewPHI, CastNodeNameSuffix),
|
|
&*Header->getFirstInsertionPt());
|
|
else
|
|
NewBasePtr = NewPHI;
|
|
}
|
|
|
|
// Clear the rewriter cache, because values that are in the rewriter's cache
|
|
// can be deleted below, causing the AssertingVH in the cache to trigger.
|
|
SCEVE.clear();
|
|
|
|
if (Instruction *IDel = dyn_cast<Instruction>(BasePtr))
|
|
BBChanged.insert(IDel->getParent());
|
|
BasePtr->replaceAllUsesWith(NewBasePtr);
|
|
RecursivelyDeleteTriviallyDeadInstructions(BasePtr);
|
|
|
|
// Keep track of the replacement pointer values we've inserted so that we
|
|
// don't generate more pointer values than necessary.
|
|
SmallPtrSet<Value *, 16> NewPtrs;
|
|
NewPtrs.insert(NewBasePtr);
|
|
|
|
for (auto I = std::next(BucketChain.Elements.begin()),
|
|
IE = BucketChain.Elements.end(); I != IE; ++I) {
|
|
Value *Ptr = GetPointerOperand(I->Instr);
|
|
assert(Ptr && "No pointer operand");
|
|
if (NewPtrs.count(Ptr))
|
|
continue;
|
|
|
|
Instruction *RealNewPtr;
|
|
if (!I->Offset || I->Offset->getValue()->isZero()) {
|
|
RealNewPtr = NewBasePtr;
|
|
} else {
|
|
Instruction *PtrIP = dyn_cast<Instruction>(Ptr);
|
|
if (PtrIP && isa<Instruction>(NewBasePtr) &&
|
|
cast<Instruction>(NewBasePtr)->getParent() == PtrIP->getParent())
|
|
PtrIP = nullptr;
|
|
else if (PtrIP && isa<PHINode>(PtrIP))
|
|
PtrIP = &*PtrIP->getParent()->getFirstInsertionPt();
|
|
else if (!PtrIP)
|
|
PtrIP = I->Instr;
|
|
|
|
GetElementPtrInst *NewPtr = GetElementPtrInst::Create(
|
|
I8Ty, PtrInc, I->Offset->getValue(),
|
|
getInstrName(I->Instr, GEPNodeOffNameSuffix), PtrIP);
|
|
if (!PtrIP)
|
|
NewPtr->insertAfter(cast<Instruction>(PtrInc));
|
|
NewPtr->setIsInBounds(IsPtrInBounds(Ptr));
|
|
RealNewPtr = NewPtr;
|
|
}
|
|
|
|
if (Instruction *IDel = dyn_cast<Instruction>(Ptr))
|
|
BBChanged.insert(IDel->getParent());
|
|
|
|
Instruction *ReplNewPtr;
|
|
if (Ptr->getType() != RealNewPtr->getType()) {
|
|
ReplNewPtr = new BitCastInst(RealNewPtr, Ptr->getType(),
|
|
getInstrName(Ptr, CastNodeNameSuffix));
|
|
ReplNewPtr->insertAfter(RealNewPtr);
|
|
} else
|
|
ReplNewPtr = RealNewPtr;
|
|
|
|
Ptr->replaceAllUsesWith(ReplNewPtr);
|
|
RecursivelyDeleteTriviallyDeadInstructions(Ptr);
|
|
|
|
NewPtrs.insert(RealNewPtr);
|
|
}
|
|
|
|
MadeChange = true;
|
|
|
|
SuccPrepCount++;
|
|
|
|
if (Form == DSForm && !CanPreInc)
|
|
DSFormChainRewritten++;
|
|
else if (Form == DQForm)
|
|
DQFormChainRewritten++;
|
|
else if (Form == UpdateForm || (Form == DSForm && CanPreInc))
|
|
UpdFormChainRewritten++;
|
|
|
|
return MadeChange;
|
|
}
|
|
|
|
bool PPCLoopInstrFormPrep::updateFormPrep(Loop *L,
|
|
SmallVector<Bucket, 16> &Buckets) {
|
|
bool MadeChange = false;
|
|
if (Buckets.empty())
|
|
return MadeChange;
|
|
SmallSet<BasicBlock *, 16> BBChanged;
|
|
for (auto &Bucket : Buckets)
|
|
// The base address of each bucket is transformed into a phi and the others
|
|
// are rewritten based on new base.
|
|
if (prepareBaseForUpdateFormChain(Bucket))
|
|
MadeChange |= rewriteLoadStores(L, Bucket, BBChanged, UpdateForm);
|
|
|
|
if (MadeChange)
|
|
for (auto &BB : L->blocks())
|
|
if (BBChanged.count(BB))
|
|
DeleteDeadPHIs(BB);
|
|
return MadeChange;
|
|
}
|
|
|
|
bool PPCLoopInstrFormPrep::dispFormPrep(Loop *L, SmallVector<Bucket, 16> &Buckets,
|
|
InstrForm Form) {
|
|
bool MadeChange = false;
|
|
|
|
if (Buckets.empty())
|
|
return MadeChange;
|
|
|
|
SmallSet<BasicBlock *, 16> BBChanged;
|
|
for (auto &Bucket : Buckets) {
|
|
if (Bucket.Elements.size() < DispFormPrepMinThreshold)
|
|
continue;
|
|
if (prepareBaseForDispFormChain(Bucket, Form))
|
|
MadeChange |= rewriteLoadStores(L, Bucket, BBChanged, Form);
|
|
}
|
|
|
|
if (MadeChange)
|
|
for (auto &BB : L->blocks())
|
|
if (BBChanged.count(BB))
|
|
DeleteDeadPHIs(BB);
|
|
return MadeChange;
|
|
}
|
|
|
|
// In order to prepare for the preferred instruction form, a PHI is added.
|
|
// This function will check to see if that PHI already exists and will return
|
|
// true if it found an existing PHI with the matched start and increment as the
|
|
// one we wanted to create.
|
|
bool PPCLoopInstrFormPrep::alreadyPrepared(Loop *L, Instruction* MemI,
|
|
const SCEV *BasePtrStartSCEV,
|
|
const SCEVConstant *BasePtrIncSCEV,
|
|
InstrForm Form) {
|
|
BasicBlock *BB = MemI->getParent();
|
|
if (!BB)
|
|
return false;
|
|
|
|
BasicBlock *PredBB = L->getLoopPredecessor();
|
|
BasicBlock *LatchBB = L->getLoopLatch();
|
|
|
|
if (!PredBB || !LatchBB)
|
|
return false;
|
|
|
|
// Run through the PHIs and see if we have some that looks like a preparation
|
|
iterator_range<BasicBlock::phi_iterator> PHIIter = BB->phis();
|
|
for (auto & CurrentPHI : PHIIter) {
|
|
PHINode *CurrentPHINode = dyn_cast<PHINode>(&CurrentPHI);
|
|
if (!CurrentPHINode)
|
|
continue;
|
|
|
|
if (!SE->isSCEVable(CurrentPHINode->getType()))
|
|
continue;
|
|
|
|
const SCEV *PHISCEV = SE->getSCEVAtScope(CurrentPHINode, L);
|
|
|
|
const SCEVAddRecExpr *PHIBasePtrSCEV = dyn_cast<SCEVAddRecExpr>(PHISCEV);
|
|
if (!PHIBasePtrSCEV)
|
|
continue;
|
|
|
|
const SCEVConstant *PHIBasePtrIncSCEV =
|
|
dyn_cast<SCEVConstant>(PHIBasePtrSCEV->getStepRecurrence(*SE));
|
|
if (!PHIBasePtrIncSCEV)
|
|
continue;
|
|
|
|
if (CurrentPHINode->getNumIncomingValues() == 2) {
|
|
if ((CurrentPHINode->getIncomingBlock(0) == LatchBB &&
|
|
CurrentPHINode->getIncomingBlock(1) == PredBB) ||
|
|
(CurrentPHINode->getIncomingBlock(1) == LatchBB &&
|
|
CurrentPHINode->getIncomingBlock(0) == PredBB)) {
|
|
if (PHIBasePtrIncSCEV == BasePtrIncSCEV) {
|
|
// The existing PHI (CurrentPHINode) has the same start and increment
|
|
// as the PHI that we wanted to create.
|
|
if (Form == UpdateForm &&
|
|
PHIBasePtrSCEV->getStart() == BasePtrStartSCEV) {
|
|
++PHINodeAlreadyExistsUpdate;
|
|
return true;
|
|
}
|
|
if (Form == DSForm || Form == DQForm) {
|
|
const SCEVConstant *Diff = dyn_cast<SCEVConstant>(
|
|
SE->getMinusSCEV(PHIBasePtrSCEV->getStart(), BasePtrStartSCEV));
|
|
if (Diff && !Diff->getAPInt().urem(Form)) {
|
|
if (Form == DSForm)
|
|
++PHINodeAlreadyExistsDS;
|
|
else
|
|
++PHINodeAlreadyExistsDQ;
|
|
return true;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
return false;
|
|
}
|
|
|
|
bool PPCLoopInstrFormPrep::runOnLoop(Loop *L) {
|
|
bool MadeChange = false;
|
|
|
|
// Only prep. the inner-most loop
|
|
if (!L->isInnermost())
|
|
return MadeChange;
|
|
|
|
// Return if already done enough preparation.
|
|
if (SuccPrepCount >= MaxVarsPrep)
|
|
return MadeChange;
|
|
|
|
LLVM_DEBUG(dbgs() << "PIP: Examining: " << *L << "\n");
|
|
|
|
BasicBlock *LoopPredecessor = L->getLoopPredecessor();
|
|
// If there is no loop predecessor, or the loop predecessor's terminator
|
|
// returns a value (which might contribute to determining the loop's
|
|
// iteration space), insert a new preheader for the loop.
|
|
if (!LoopPredecessor ||
|
|
!LoopPredecessor->getTerminator()->getType()->isVoidTy()) {
|
|
LoopPredecessor = InsertPreheaderForLoop(L, DT, LI, nullptr, PreserveLCSSA);
|
|
if (LoopPredecessor)
|
|
MadeChange = true;
|
|
}
|
|
if (!LoopPredecessor) {
|
|
LLVM_DEBUG(dbgs() << "PIP fails since no predecessor for current loop.\n");
|
|
return MadeChange;
|
|
}
|
|
// Check if a load/store has update form. This lambda is used by function
|
|
// collectCandidates which can collect candidates for types defined by lambda.
|
|
auto isUpdateFormCandidate = [&] (const Instruction *I,
|
|
const Value *PtrValue) {
|
|
assert((PtrValue && I) && "Invalid parameter!");
|
|
// There are no update forms for Altivec vector load/stores.
|
|
if (ST && ST->hasAltivec() &&
|
|
PtrValue->getType()->getPointerElementType()->isVectorTy())
|
|
return false;
|
|
// There are no update forms for P10 lxvp/stxvp intrinsic.
|
|
auto *II = dyn_cast<IntrinsicInst>(I);
|
|
if (II && ((II->getIntrinsicID() == Intrinsic::ppc_mma_lxvp) ||
|
|
II->getIntrinsicID() == Intrinsic::ppc_mma_stxvp))
|
|
return false;
|
|
// See getPreIndexedAddressParts, the displacement for LDU/STDU has to
|
|
// be 4's multiple (DS-form). For i64 loads/stores when the displacement
|
|
// fits in a 16-bit signed field but isn't a multiple of 4, it will be
|
|
// useless and possible to break some original well-form addressing mode
|
|
// to make this pre-inc prep for it.
|
|
if (PtrValue->getType()->getPointerElementType()->isIntegerTy(64)) {
|
|
const SCEV *LSCEV = SE->getSCEVAtScope(const_cast<Value *>(PtrValue), L);
|
|
const SCEVAddRecExpr *LARSCEV = dyn_cast<SCEVAddRecExpr>(LSCEV);
|
|
if (!LARSCEV || LARSCEV->getLoop() != L)
|
|
return false;
|
|
if (const SCEVConstant *StepConst =
|
|
dyn_cast<SCEVConstant>(LARSCEV->getStepRecurrence(*SE))) {
|
|
const APInt &ConstInt = StepConst->getValue()->getValue();
|
|
if (ConstInt.isSignedIntN(16) && ConstInt.srem(4) != 0)
|
|
return false;
|
|
}
|
|
}
|
|
return true;
|
|
};
|
|
|
|
// Check if a load/store has DS form.
|
|
auto isDSFormCandidate = [] (const Instruction *I, const Value *PtrValue) {
|
|
assert((PtrValue && I) && "Invalid parameter!");
|
|
if (isa<IntrinsicInst>(I))
|
|
return false;
|
|
Type *PointerElementType = PtrValue->getType()->getPointerElementType();
|
|
return (PointerElementType->isIntegerTy(64)) ||
|
|
(PointerElementType->isFloatTy()) ||
|
|
(PointerElementType->isDoubleTy()) ||
|
|
(PointerElementType->isIntegerTy(32) &&
|
|
llvm::any_of(I->users(),
|
|
[](const User *U) { return isa<SExtInst>(U); }));
|
|
};
|
|
|
|
// Check if a load/store has DQ form.
|
|
auto isDQFormCandidate = [&] (const Instruction *I, const Value *PtrValue) {
|
|
assert((PtrValue && I) && "Invalid parameter!");
|
|
// Check if it is a P10 lxvp/stxvp intrinsic.
|
|
auto *II = dyn_cast<IntrinsicInst>(I);
|
|
if (II)
|
|
return II->getIntrinsicID() == Intrinsic::ppc_mma_lxvp ||
|
|
II->getIntrinsicID() == Intrinsic::ppc_mma_stxvp;
|
|
// Check if it is a P9 vector load/store.
|
|
return ST && ST->hasP9Vector() &&
|
|
(PtrValue->getType()->getPointerElementType()->isVectorTy());
|
|
};
|
|
|
|
// intrinsic for update form.
|
|
SmallVector<Bucket, 16> UpdateFormBuckets =
|
|
collectCandidates(L, isUpdateFormCandidate, MaxVarsUpdateForm);
|
|
|
|
// Prepare for update form.
|
|
if (!UpdateFormBuckets.empty())
|
|
MadeChange |= updateFormPrep(L, UpdateFormBuckets);
|
|
|
|
// Collect buckets of comparable addresses used by loads and stores for DS
|
|
// form.
|
|
SmallVector<Bucket, 16> DSFormBuckets =
|
|
collectCandidates(L, isDSFormCandidate, MaxVarsDSForm);
|
|
|
|
// Prepare for DS form.
|
|
if (!DSFormBuckets.empty())
|
|
MadeChange |= dispFormPrep(L, DSFormBuckets, DSForm);
|
|
|
|
// Collect buckets of comparable addresses used by loads and stores for DQ
|
|
// form.
|
|
SmallVector<Bucket, 16> DQFormBuckets =
|
|
collectCandidates(L, isDQFormCandidate, MaxVarsDQForm);
|
|
|
|
// Prepare for DQ form.
|
|
if (!DQFormBuckets.empty())
|
|
MadeChange |= dispFormPrep(L, DQFormBuckets, DQForm);
|
|
|
|
return MadeChange;
|
|
}
|