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https://github.com/c64scene-ar/llvm-6502.git
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@139565 91177308-0d34-0410-b5e6-96231b3b80d8
635 lines
25 KiB
C++
635 lines
25 KiB
C++
//===-- LoopIdiomRecognize.cpp - Loop idiom recognition -------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This pass implements an idiom recognizer that transforms simple loops into a
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// non-loop form. In cases that this kicks in, it can be a significant
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// performance win.
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//
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//===----------------------------------------------------------------------===//
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//
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// TODO List:
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//
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// Future loop memory idioms to recognize:
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// memcmp, memmove, strlen, etc.
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// Future floating point idioms to recognize in -ffast-math mode:
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// fpowi
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// Future integer operation idioms to recognize:
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// ctpop, ctlz, cttz
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//
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// Beware that isel's default lowering for ctpop is highly inefficient for
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// i64 and larger types when i64 is legal and the value has few bits set. It
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// would be good to enhance isel to emit a loop for ctpop in this case.
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//
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// We should enhance the memset/memcpy recognition to handle multiple stores in
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// the loop. This would handle things like:
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// void foo(_Complex float *P)
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// for (i) { __real__(*P) = 0; __imag__(*P) = 0; }
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//
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// We should enhance this to handle negative strides through memory.
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// Alternatively (and perhaps better) we could rely on an earlier pass to force
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// forward iteration through memory, which is generally better for cache
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// behavior. Negative strides *do* happen for memset/memcpy loops.
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//
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// This could recognize common matrix multiplies and dot product idioms and
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// replace them with calls to BLAS (if linked in??).
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "loop-idiom"
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#include "llvm/Transforms/Scalar.h"
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#include "llvm/IntrinsicInst.h"
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#include "llvm/Module.h"
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#include "llvm/Analysis/AliasAnalysis.h"
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#include "llvm/Analysis/LoopPass.h"
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#include "llvm/Analysis/ScalarEvolutionExpressions.h"
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#include "llvm/Analysis/ScalarEvolutionExpander.h"
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#include "llvm/Analysis/ValueTracking.h"
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#include "llvm/Target/TargetData.h"
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#include "llvm/Target/TargetLibraryInfo.h"
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#include "llvm/Transforms/Utils/Local.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/IRBuilder.h"
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#include "llvm/Support/raw_ostream.h"
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#include "llvm/ADT/Statistic.h"
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using namespace llvm;
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STATISTIC(NumMemSet, "Number of memset's formed from loop stores");
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STATISTIC(NumMemCpy, "Number of memcpy's formed from loop load+stores");
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namespace {
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class LoopIdiomRecognize : public LoopPass {
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Loop *CurLoop;
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const TargetData *TD;
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DominatorTree *DT;
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ScalarEvolution *SE;
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TargetLibraryInfo *TLI;
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public:
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static char ID;
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explicit LoopIdiomRecognize() : LoopPass(ID) {
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initializeLoopIdiomRecognizePass(*PassRegistry::getPassRegistry());
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}
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bool runOnLoop(Loop *L, LPPassManager &LPM);
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bool runOnLoopBlock(BasicBlock *BB, const SCEV *BECount,
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SmallVectorImpl<BasicBlock*> &ExitBlocks);
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bool processLoopStore(StoreInst *SI, const SCEV *BECount);
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bool processLoopMemSet(MemSetInst *MSI, const SCEV *BECount);
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bool processLoopStridedStore(Value *DestPtr, unsigned StoreSize,
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unsigned StoreAlignment,
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Value *SplatValue, Instruction *TheStore,
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const SCEVAddRecExpr *Ev,
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const SCEV *BECount);
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bool processLoopStoreOfLoopLoad(StoreInst *SI, unsigned StoreSize,
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const SCEVAddRecExpr *StoreEv,
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const SCEVAddRecExpr *LoadEv,
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const SCEV *BECount);
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/// This transformation requires natural loop information & requires that
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/// loop preheaders be inserted into the CFG.
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///
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virtual void getAnalysisUsage(AnalysisUsage &AU) const {
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AU.addRequired<LoopInfo>();
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AU.addPreserved<LoopInfo>();
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AU.addRequiredID(LoopSimplifyID);
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AU.addPreservedID(LoopSimplifyID);
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AU.addRequiredID(LCSSAID);
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AU.addPreservedID(LCSSAID);
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AU.addRequired<AliasAnalysis>();
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AU.addPreserved<AliasAnalysis>();
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AU.addRequired<ScalarEvolution>();
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AU.addPreserved<ScalarEvolution>();
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AU.addPreserved<DominatorTree>();
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AU.addRequired<DominatorTree>();
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AU.addRequired<TargetLibraryInfo>();
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}
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};
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}
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char LoopIdiomRecognize::ID = 0;
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INITIALIZE_PASS_BEGIN(LoopIdiomRecognize, "loop-idiom", "Recognize loop idioms",
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false, false)
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INITIALIZE_PASS_DEPENDENCY(LoopInfo)
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INITIALIZE_PASS_DEPENDENCY(DominatorTree)
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INITIALIZE_PASS_DEPENDENCY(LoopSimplify)
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INITIALIZE_PASS_DEPENDENCY(LCSSA)
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INITIALIZE_PASS_DEPENDENCY(ScalarEvolution)
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INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfo)
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INITIALIZE_AG_DEPENDENCY(AliasAnalysis)
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INITIALIZE_PASS_END(LoopIdiomRecognize, "loop-idiom", "Recognize loop idioms",
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false, false)
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Pass *llvm::createLoopIdiomPass() { return new LoopIdiomRecognize(); }
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/// deleteDeadInstruction - Delete this instruction. Before we do, go through
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/// and zero out all the operands of this instruction. If any of them become
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/// dead, delete them and the computation tree that feeds them.
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///
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static void deleteDeadInstruction(Instruction *I, ScalarEvolution &SE) {
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SmallVector<Instruction*, 32> NowDeadInsts;
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NowDeadInsts.push_back(I);
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// Before we touch this instruction, remove it from SE!
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do {
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Instruction *DeadInst = NowDeadInsts.pop_back_val();
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// This instruction is dead, zap it, in stages. Start by removing it from
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// SCEV.
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SE.forgetValue(DeadInst);
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for (unsigned op = 0, e = DeadInst->getNumOperands(); op != e; ++op) {
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Value *Op = DeadInst->getOperand(op);
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DeadInst->setOperand(op, 0);
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// If this operand just became dead, add it to the NowDeadInsts list.
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if (!Op->use_empty()) continue;
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if (Instruction *OpI = dyn_cast<Instruction>(Op))
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if (isInstructionTriviallyDead(OpI))
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NowDeadInsts.push_back(OpI);
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}
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DeadInst->eraseFromParent();
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} while (!NowDeadInsts.empty());
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}
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/// deleteIfDeadInstruction - If the specified value is a dead instruction,
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/// delete it and any recursively used instructions.
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static void deleteIfDeadInstruction(Value *V, ScalarEvolution &SE) {
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if (Instruction *I = dyn_cast<Instruction>(V))
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if (isInstructionTriviallyDead(I))
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deleteDeadInstruction(I, SE);
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}
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bool LoopIdiomRecognize::runOnLoop(Loop *L, LPPassManager &LPM) {
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CurLoop = L;
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// Disable loop idiom recognition if the function's name is a common idiom.
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StringRef Name = L->getHeader()->getParent()->getName();
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if (Name == "memset" || Name == "memcpy")
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return false;
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// The trip count of the loop must be analyzable.
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SE = &getAnalysis<ScalarEvolution>();
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if (!SE->hasLoopInvariantBackedgeTakenCount(L))
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return false;
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const SCEV *BECount = SE->getBackedgeTakenCount(L);
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if (isa<SCEVCouldNotCompute>(BECount)) return false;
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// If this loop executes exactly one time, then it should be peeled, not
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// optimized by this pass.
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if (const SCEVConstant *BECst = dyn_cast<SCEVConstant>(BECount))
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if (BECst->getValue()->getValue() == 0)
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return false;
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// We require target data for now.
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TD = getAnalysisIfAvailable<TargetData>();
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if (TD == 0) return false;
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DT = &getAnalysis<DominatorTree>();
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LoopInfo &LI = getAnalysis<LoopInfo>();
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TLI = &getAnalysis<TargetLibraryInfo>();
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SmallVector<BasicBlock*, 8> ExitBlocks;
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CurLoop->getUniqueExitBlocks(ExitBlocks);
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DEBUG(dbgs() << "loop-idiom Scanning: F["
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<< L->getHeader()->getParent()->getName()
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<< "] Loop %" << L->getHeader()->getName() << "\n");
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bool MadeChange = false;
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// Scan all the blocks in the loop that are not in subloops.
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for (Loop::block_iterator BI = L->block_begin(), E = L->block_end(); BI != E;
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++BI) {
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// Ignore blocks in subloops.
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if (LI.getLoopFor(*BI) != CurLoop)
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continue;
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MadeChange |= runOnLoopBlock(*BI, BECount, ExitBlocks);
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}
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return MadeChange;
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}
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/// runOnLoopBlock - Process the specified block, which lives in a counted loop
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/// with the specified backedge count. This block is known to be in the current
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/// loop and not in any subloops.
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bool LoopIdiomRecognize::runOnLoopBlock(BasicBlock *BB, const SCEV *BECount,
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SmallVectorImpl<BasicBlock*> &ExitBlocks) {
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// We can only promote stores in this block if they are unconditionally
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// executed in the loop. For a block to be unconditionally executed, it has
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// to dominate all the exit blocks of the loop. Verify this now.
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for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i)
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if (!DT->dominates(BB, ExitBlocks[i]))
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return false;
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bool MadeChange = false;
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for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ) {
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Instruction *Inst = I++;
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// Look for store instructions, which may be optimized to memset/memcpy.
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if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
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WeakVH InstPtr(I);
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if (!processLoopStore(SI, BECount)) continue;
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MadeChange = true;
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// If processing the store invalidated our iterator, start over from the
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// top of the block.
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if (InstPtr == 0)
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I = BB->begin();
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continue;
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}
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// Look for memset instructions, which may be optimized to a larger memset.
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if (MemSetInst *MSI = dyn_cast<MemSetInst>(Inst)) {
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WeakVH InstPtr(I);
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if (!processLoopMemSet(MSI, BECount)) continue;
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MadeChange = true;
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// If processing the memset invalidated our iterator, start over from the
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// top of the block.
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if (InstPtr == 0)
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I = BB->begin();
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continue;
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}
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}
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return MadeChange;
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}
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/// processLoopStore - See if this store can be promoted to a memset or memcpy.
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bool LoopIdiomRecognize::processLoopStore(StoreInst *SI, const SCEV *BECount) {
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if (!SI->isSimple()) return false;
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Value *StoredVal = SI->getValueOperand();
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Value *StorePtr = SI->getPointerOperand();
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// Reject stores that are so large that they overflow an unsigned.
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uint64_t SizeInBits = TD->getTypeSizeInBits(StoredVal->getType());
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if ((SizeInBits & 7) || (SizeInBits >> 32) != 0)
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return false;
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// See if the pointer expression is an AddRec like {base,+,1} on the current
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// loop, which indicates a strided store. If we have something else, it's a
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// random store we can't handle.
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const SCEVAddRecExpr *StoreEv =
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dyn_cast<SCEVAddRecExpr>(SE->getSCEV(StorePtr));
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if (StoreEv == 0 || StoreEv->getLoop() != CurLoop || !StoreEv->isAffine())
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return false;
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// Check to see if the stride matches the size of the store. If so, then we
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// know that every byte is touched in the loop.
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unsigned StoreSize = (unsigned)SizeInBits >> 3;
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const SCEVConstant *Stride = dyn_cast<SCEVConstant>(StoreEv->getOperand(1));
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if (Stride == 0 || StoreSize != Stride->getValue()->getValue()) {
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// TODO: Could also handle negative stride here someday, that will require
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// the validity check in mayLoopAccessLocation to be updated though.
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// Enable this to print exact negative strides.
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if (0 && Stride && StoreSize == -Stride->getValue()->getValue()) {
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dbgs() << "NEGATIVE STRIDE: " << *SI << "\n";
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dbgs() << "BB: " << *SI->getParent();
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}
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return false;
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}
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// See if we can optimize just this store in isolation.
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if (processLoopStridedStore(StorePtr, StoreSize, SI->getAlignment(),
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StoredVal, SI, StoreEv, BECount))
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return true;
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// If the stored value is a strided load in the same loop with the same stride
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// this this may be transformable into a memcpy. This kicks in for stuff like
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// for (i) A[i] = B[i];
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if (LoadInst *LI = dyn_cast<LoadInst>(StoredVal)) {
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const SCEVAddRecExpr *LoadEv =
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dyn_cast<SCEVAddRecExpr>(SE->getSCEV(LI->getOperand(0)));
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if (LoadEv && LoadEv->getLoop() == CurLoop && LoadEv->isAffine() &&
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StoreEv->getOperand(1) == LoadEv->getOperand(1) && LI->isSimple())
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if (processLoopStoreOfLoopLoad(SI, StoreSize, StoreEv, LoadEv, BECount))
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return true;
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}
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//errs() << "UNHANDLED strided store: " << *StoreEv << " - " << *SI << "\n";
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return false;
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}
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/// processLoopMemSet - See if this memset can be promoted to a large memset.
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bool LoopIdiomRecognize::
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processLoopMemSet(MemSetInst *MSI, const SCEV *BECount) {
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// We can only handle non-volatile memsets with a constant size.
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if (MSI->isVolatile() || !isa<ConstantInt>(MSI->getLength())) return false;
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// If we're not allowed to hack on memset, we fail.
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if (!TLI->has(LibFunc::memset))
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return false;
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Value *Pointer = MSI->getDest();
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// See if the pointer expression is an AddRec like {base,+,1} on the current
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// loop, which indicates a strided store. If we have something else, it's a
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// random store we can't handle.
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const SCEVAddRecExpr *Ev = dyn_cast<SCEVAddRecExpr>(SE->getSCEV(Pointer));
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if (Ev == 0 || Ev->getLoop() != CurLoop || !Ev->isAffine())
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return false;
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// Reject memsets that are so large that they overflow an unsigned.
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uint64_t SizeInBytes = cast<ConstantInt>(MSI->getLength())->getZExtValue();
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if ((SizeInBytes >> 32) != 0)
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return false;
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// Check to see if the stride matches the size of the memset. If so, then we
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// know that every byte is touched in the loop.
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const SCEVConstant *Stride = dyn_cast<SCEVConstant>(Ev->getOperand(1));
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// TODO: Could also handle negative stride here someday, that will require the
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// validity check in mayLoopAccessLocation to be updated though.
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if (Stride == 0 || MSI->getLength() != Stride->getValue())
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return false;
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return processLoopStridedStore(Pointer, (unsigned)SizeInBytes,
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MSI->getAlignment(), MSI->getValue(),
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MSI, Ev, BECount);
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}
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/// mayLoopAccessLocation - Return true if the specified loop might access the
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/// specified pointer location, which is a loop-strided access. The 'Access'
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/// argument specifies what the verboten forms of access are (read or write).
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static bool mayLoopAccessLocation(Value *Ptr,AliasAnalysis::ModRefResult Access,
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Loop *L, const SCEV *BECount,
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unsigned StoreSize, AliasAnalysis &AA,
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Instruction *IgnoredStore) {
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// Get the location that may be stored across the loop. Since the access is
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// strided positively through memory, we say that the modified location starts
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// at the pointer and has infinite size.
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uint64_t AccessSize = AliasAnalysis::UnknownSize;
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// If the loop iterates a fixed number of times, we can refine the access size
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// to be exactly the size of the memset, which is (BECount+1)*StoreSize
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if (const SCEVConstant *BECst = dyn_cast<SCEVConstant>(BECount))
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AccessSize = (BECst->getValue()->getZExtValue()+1)*StoreSize;
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// TODO: For this to be really effective, we have to dive into the pointer
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// operand in the store. Store to &A[i] of 100 will always return may alias
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// with store of &A[100], we need to StoreLoc to be "A" with size of 100,
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// which will then no-alias a store to &A[100].
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AliasAnalysis::Location StoreLoc(Ptr, AccessSize);
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for (Loop::block_iterator BI = L->block_begin(), E = L->block_end(); BI != E;
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++BI)
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for (BasicBlock::iterator I = (*BI)->begin(), E = (*BI)->end(); I != E; ++I)
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if (&*I != IgnoredStore &&
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(AA.getModRefInfo(I, StoreLoc) & Access))
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return true;
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return false;
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}
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/// getMemSetPatternValue - If a strided store of the specified value is safe to
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/// turn into a memset_pattern16, return a ConstantArray of 16 bytes that should
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/// be passed in. Otherwise, return null.
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///
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/// Note that we don't ever attempt to use memset_pattern8 or 4, because these
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/// just replicate their input array and then pass on to memset_pattern16.
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static Constant *getMemSetPatternValue(Value *V, const TargetData &TD) {
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// If the value isn't a constant, we can't promote it to being in a constant
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// array. We could theoretically do a store to an alloca or something, but
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// that doesn't seem worthwhile.
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Constant *C = dyn_cast<Constant>(V);
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if (C == 0) return 0;
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// Only handle simple values that are a power of two bytes in size.
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uint64_t Size = TD.getTypeSizeInBits(V->getType());
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if (Size == 0 || (Size & 7) || (Size & (Size-1)))
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return 0;
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// Don't care enough about darwin/ppc to implement this.
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if (TD.isBigEndian())
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return 0;
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// Convert to size in bytes.
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Size /= 8;
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// TODO: If CI is larger than 16-bytes, we can try slicing it in half to see
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// if the top and bottom are the same (e.g. for vectors and large integers).
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if (Size > 16) return 0;
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// If the constant is exactly 16 bytes, just use it.
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if (Size == 16) return C;
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// Otherwise, we'll use an array of the constants.
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unsigned ArraySize = 16/Size;
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ArrayType *AT = ArrayType::get(V->getType(), ArraySize);
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return ConstantArray::get(AT, std::vector<Constant*>(ArraySize, C));
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}
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/// processLoopStridedStore - We see a strided store of some value. If we can
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/// transform this into a memset or memset_pattern in the loop preheader, do so.
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bool LoopIdiomRecognize::
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processLoopStridedStore(Value *DestPtr, unsigned StoreSize,
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unsigned StoreAlignment, Value *StoredVal,
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Instruction *TheStore, const SCEVAddRecExpr *Ev,
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const SCEV *BECount) {
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// If the stored value is a byte-wise value (like i32 -1), then it may be
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// turned into a memset of i8 -1, assuming that all the consecutive bytes
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// are stored. A store of i32 0x01020304 can never be turned into a memset,
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// but it can be turned into memset_pattern if the target supports it.
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Value *SplatValue = isBytewiseValue(StoredVal);
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Constant *PatternValue = 0;
|
|
|
|
// If we're allowed to form a memset, and the stored value would be acceptable
|
|
// for memset, use it.
|
|
if (SplatValue && TLI->has(LibFunc::memset) &&
|
|
// Verify that the stored value is loop invariant. If not, we can't
|
|
// promote the memset.
|
|
CurLoop->isLoopInvariant(SplatValue)) {
|
|
// Keep and use SplatValue.
|
|
PatternValue = 0;
|
|
} else if (TLI->has(LibFunc::memset_pattern16) &&
|
|
(PatternValue = getMemSetPatternValue(StoredVal, *TD))) {
|
|
// It looks like we can use PatternValue!
|
|
SplatValue = 0;
|
|
} else {
|
|
// Otherwise, this isn't an idiom we can transform. For example, we can't
|
|
// do anything with a 3-byte store.
|
|
return false;
|
|
}
|
|
|
|
// The trip count of the loop and the base pointer of the addrec SCEV is
|
|
// guaranteed to be loop invariant, which means that it should dominate the
|
|
// header. This allows us to insert code for it in the preheader.
|
|
BasicBlock *Preheader = CurLoop->getLoopPreheader();
|
|
IRBuilder<> Builder(Preheader->getTerminator());
|
|
SCEVExpander Expander(*SE, "loop-idiom");
|
|
|
|
// Okay, we have a strided store "p[i]" of a splattable value. We can turn
|
|
// this into a memset in the loop preheader now if we want. However, this
|
|
// would be unsafe to do if there is anything else in the loop that may read
|
|
// or write to the aliased location. Check for any overlap by generating the
|
|
// base pointer and checking the region.
|
|
unsigned AddrSpace = cast<PointerType>(DestPtr->getType())->getAddressSpace();
|
|
Value *BasePtr =
|
|
Expander.expandCodeFor(Ev->getStart(), Builder.getInt8PtrTy(AddrSpace),
|
|
Preheader->getTerminator());
|
|
|
|
|
|
if (mayLoopAccessLocation(BasePtr, AliasAnalysis::ModRef,
|
|
CurLoop, BECount,
|
|
StoreSize, getAnalysis<AliasAnalysis>(), TheStore)){
|
|
Expander.clear();
|
|
// If we generated new code for the base pointer, clean up.
|
|
deleteIfDeadInstruction(BasePtr, *SE);
|
|
return false;
|
|
}
|
|
|
|
// Okay, everything looks good, insert the memset.
|
|
|
|
// The # stored bytes is (BECount+1)*Size. Expand the trip count out to
|
|
// pointer size if it isn't already.
|
|
Type *IntPtr = TD->getIntPtrType(DestPtr->getContext());
|
|
BECount = SE->getTruncateOrZeroExtend(BECount, IntPtr);
|
|
|
|
const SCEV *NumBytesS = SE->getAddExpr(BECount, SE->getConstant(IntPtr, 1),
|
|
SCEV::FlagNUW);
|
|
if (StoreSize != 1)
|
|
NumBytesS = SE->getMulExpr(NumBytesS, SE->getConstant(IntPtr, StoreSize),
|
|
SCEV::FlagNUW);
|
|
|
|
Value *NumBytes =
|
|
Expander.expandCodeFor(NumBytesS, IntPtr, Preheader->getTerminator());
|
|
|
|
CallInst *NewCall;
|
|
if (SplatValue)
|
|
NewCall = Builder.CreateMemSet(BasePtr, SplatValue,NumBytes,StoreAlignment);
|
|
else {
|
|
Module *M = TheStore->getParent()->getParent()->getParent();
|
|
Value *MSP = M->getOrInsertFunction("memset_pattern16",
|
|
Builder.getVoidTy(),
|
|
Builder.getInt8PtrTy(),
|
|
Builder.getInt8PtrTy(), IntPtr,
|
|
(void*)0);
|
|
|
|
// Otherwise we should form a memset_pattern16. PatternValue is known to be
|
|
// an constant array of 16-bytes. Plop the value into a mergable global.
|
|
GlobalVariable *GV = new GlobalVariable(*M, PatternValue->getType(), true,
|
|
GlobalValue::InternalLinkage,
|
|
PatternValue, ".memset_pattern");
|
|
GV->setUnnamedAddr(true); // Ok to merge these.
|
|
GV->setAlignment(16);
|
|
Value *PatternPtr = ConstantExpr::getBitCast(GV, Builder.getInt8PtrTy());
|
|
NewCall = Builder.CreateCall3(MSP, BasePtr, PatternPtr, NumBytes);
|
|
}
|
|
|
|
DEBUG(dbgs() << " Formed memset: " << *NewCall << "\n"
|
|
<< " from store to: " << *Ev << " at: " << *TheStore << "\n");
|
|
NewCall->setDebugLoc(TheStore->getDebugLoc());
|
|
|
|
// Okay, the memset has been formed. Zap the original store and anything that
|
|
// feeds into it.
|
|
deleteDeadInstruction(TheStore, *SE);
|
|
++NumMemSet;
|
|
return true;
|
|
}
|
|
|
|
/// processLoopStoreOfLoopLoad - We see a strided store whose value is a
|
|
/// same-strided load.
|
|
bool LoopIdiomRecognize::
|
|
processLoopStoreOfLoopLoad(StoreInst *SI, unsigned StoreSize,
|
|
const SCEVAddRecExpr *StoreEv,
|
|
const SCEVAddRecExpr *LoadEv,
|
|
const SCEV *BECount) {
|
|
// If we're not allowed to form memcpy, we fail.
|
|
if (!TLI->has(LibFunc::memcpy))
|
|
return false;
|
|
|
|
LoadInst *LI = cast<LoadInst>(SI->getValueOperand());
|
|
|
|
// The trip count of the loop and the base pointer of the addrec SCEV is
|
|
// guaranteed to be loop invariant, which means that it should dominate the
|
|
// header. This allows us to insert code for it in the preheader.
|
|
BasicBlock *Preheader = CurLoop->getLoopPreheader();
|
|
IRBuilder<> Builder(Preheader->getTerminator());
|
|
SCEVExpander Expander(*SE, "loop-idiom");
|
|
|
|
// Okay, we have a strided store "p[i]" of a loaded value. We can turn
|
|
// this into a memcpy in the loop preheader now if we want. However, this
|
|
// would be unsafe to do if there is anything else in the loop that may read
|
|
// or write the memory region we're storing to. This includes the load that
|
|
// feeds the stores. Check for an alias by generating the base address and
|
|
// checking everything.
|
|
Value *StoreBasePtr =
|
|
Expander.expandCodeFor(StoreEv->getStart(),
|
|
Builder.getInt8PtrTy(SI->getPointerAddressSpace()),
|
|
Preheader->getTerminator());
|
|
|
|
if (mayLoopAccessLocation(StoreBasePtr, AliasAnalysis::ModRef,
|
|
CurLoop, BECount, StoreSize,
|
|
getAnalysis<AliasAnalysis>(), SI)) {
|
|
Expander.clear();
|
|
// If we generated new code for the base pointer, clean up.
|
|
deleteIfDeadInstruction(StoreBasePtr, *SE);
|
|
return false;
|
|
}
|
|
|
|
// For a memcpy, we have to make sure that the input array is not being
|
|
// mutated by the loop.
|
|
Value *LoadBasePtr =
|
|
Expander.expandCodeFor(LoadEv->getStart(),
|
|
Builder.getInt8PtrTy(LI->getPointerAddressSpace()),
|
|
Preheader->getTerminator());
|
|
|
|
if (mayLoopAccessLocation(LoadBasePtr, AliasAnalysis::Mod, CurLoop, BECount,
|
|
StoreSize, getAnalysis<AliasAnalysis>(), SI)) {
|
|
Expander.clear();
|
|
// If we generated new code for the base pointer, clean up.
|
|
deleteIfDeadInstruction(LoadBasePtr, *SE);
|
|
deleteIfDeadInstruction(StoreBasePtr, *SE);
|
|
return false;
|
|
}
|
|
|
|
// Okay, everything is safe, we can transform this!
|
|
|
|
|
|
// The # stored bytes is (BECount+1)*Size. Expand the trip count out to
|
|
// pointer size if it isn't already.
|
|
Type *IntPtr = TD->getIntPtrType(SI->getContext());
|
|
BECount = SE->getTruncateOrZeroExtend(BECount, IntPtr);
|
|
|
|
const SCEV *NumBytesS = SE->getAddExpr(BECount, SE->getConstant(IntPtr, 1),
|
|
SCEV::FlagNUW);
|
|
if (StoreSize != 1)
|
|
NumBytesS = SE->getMulExpr(NumBytesS, SE->getConstant(IntPtr, StoreSize),
|
|
SCEV::FlagNUW);
|
|
|
|
Value *NumBytes =
|
|
Expander.expandCodeFor(NumBytesS, IntPtr, Preheader->getTerminator());
|
|
|
|
CallInst *NewCall =
|
|
Builder.CreateMemCpy(StoreBasePtr, LoadBasePtr, NumBytes,
|
|
std::min(SI->getAlignment(), LI->getAlignment()));
|
|
NewCall->setDebugLoc(SI->getDebugLoc());
|
|
|
|
DEBUG(dbgs() << " Formed memcpy: " << *NewCall << "\n"
|
|
<< " from load ptr=" << *LoadEv << " at: " << *LI << "\n"
|
|
<< " from store ptr=" << *StoreEv << " at: " << *SI << "\n");
|
|
|
|
|
|
// Okay, the memset has been formed. Zap the original store and anything that
|
|
// feeds into it.
|
|
deleteDeadInstruction(SI, *SE);
|
|
++NumMemCpy;
|
|
return true;
|
|
}
|