// performance win.
//
//===----------------------------------------------------------------------===//
+//
+// TODO List:
+//
+// Future loop memory idioms to recognize:
+// memcmp, memmove, strlen, etc.
+// Future floating point idioms to recognize in -ffast-math mode:
+// fpowi
+// Future integer operation idioms to recognize:
+// ctpop, ctlz, cttz
+//
+// Beware that isel's default lowering for ctpop is highly inefficient for
+// i64 and larger types when i64 is legal and the value has few bits set. It
+// would be good to enhance isel to emit a loop for ctpop in this case.
+//
+// We should enhance the memset/memcpy recognition to handle multiple stores in
+// the loop. This would handle things like:
+// void foo(_Complex float *P)
+// for (i) { __real__(*P) = 0; __imag__(*P) = 0; }
+//
+// We should enhance this to handle negative strides through memory.
+// Alternatively (and perhaps better) we could rely on an earlier pass to force
+// forward iteration through memory, which is generally better for cache
+// behavior. Negative strides *do* happen for memset/memcpy loops.
+//
+// This could recognize common matrix multiplies and dot product idioms and
+// replace them with calls to BLAS (if linked in??).
+//
+//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "loop-idiom"
#include "llvm/Transforms/Scalar.h"
+#include "llvm/IRBuilder.h"
+#include "llvm/IntrinsicInst.h"
+#include "llvm/Module.h"
+#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/LoopPass.h"
-#include "llvm/Analysis/ScalarEvolutionExpressions.h"
#include "llvm/Analysis/ScalarEvolutionExpander.h"
+#include "llvm/Analysis/ScalarEvolutionExpressions.h"
#include "llvm/Analysis/ValueTracking.h"
-#include "llvm/Target/TargetData.h"
-#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Support/Debug.h"
-#include "llvm/Support/IRBuilder.h"
#include "llvm/Support/raw_ostream.h"
+#include "llvm/DataLayout.h"
+#include "llvm/Target/TargetLibraryInfo.h"
+#include "llvm/Transforms/Utils/Local.h"
using namespace llvm;
-// TODO: Recognize "N" size array multiplies: replace with call to blas or
-// something.
+STATISTIC(NumMemSet, "Number of memset's formed from loop stores");
+STATISTIC(NumMemCpy, "Number of memcpy's formed from loop load+stores");
namespace {
class LoopIdiomRecognize : public LoopPass {
Loop *CurLoop;
- const TargetData *TD;
+ const DataLayout *TD;
+ DominatorTree *DT;
ScalarEvolution *SE;
+ TargetLibraryInfo *TLI;
public:
static char ID;
explicit LoopIdiomRecognize() : LoopPass(ID) {
}
bool runOnLoop(Loop *L, LPPassManager &LPM);
+ bool runOnLoopBlock(BasicBlock *BB, const SCEV *BECount,
+ SmallVectorImpl<BasicBlock*> &ExitBlocks);
bool processLoopStore(StoreInst *SI, const SCEV *BECount);
-
- bool processLoopStoreOfSplatValue(StoreInst *SI, unsigned StoreSize,
- Value *SplatValue,
- const SCEVAddRecExpr *Ev,
- const SCEV *BECount);
+ bool processLoopMemSet(MemSetInst *MSI, const SCEV *BECount);
+
+ bool processLoopStridedStore(Value *DestPtr, unsigned StoreSize,
+ unsigned StoreAlignment,
+ Value *SplatValue, Instruction *TheStore,
+ const SCEVAddRecExpr *Ev,
+ const SCEV *BECount);
bool processLoopStoreOfLoopLoad(StoreInst *SI, unsigned StoreSize,
const SCEVAddRecExpr *StoreEv,
const SCEVAddRecExpr *LoadEv,
const SCEV *BECount);
-
+
/// This transformation requires natural loop information & requires that
/// loop preheaders be inserted into the CFG.
///
AU.addRequired<ScalarEvolution>();
AU.addPreserved<ScalarEvolution>();
AU.addPreserved<DominatorTree>();
+ AU.addRequired<DominatorTree>();
+ AU.addRequired<TargetLibraryInfo>();
}
};
}
INITIALIZE_PASS_BEGIN(LoopIdiomRecognize, "loop-idiom", "Recognize loop idioms",
false, false)
INITIALIZE_PASS_DEPENDENCY(LoopInfo)
+INITIALIZE_PASS_DEPENDENCY(DominatorTree)
INITIALIZE_PASS_DEPENDENCY(LoopSimplify)
INITIALIZE_PASS_DEPENDENCY(LCSSA)
INITIALIZE_PASS_DEPENDENCY(ScalarEvolution)
+INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfo)
INITIALIZE_AG_DEPENDENCY(AliasAnalysis)
INITIALIZE_PASS_END(LoopIdiomRecognize, "loop-idiom", "Recognize loop idioms",
false, false)
Pass *llvm::createLoopIdiomPass() { return new LoopIdiomRecognize(); }
-/// DeleteDeadInstruction - Delete this instruction. Before we do, go through
+/// deleteDeadInstruction - Delete this instruction. Before we do, go through
/// and zero out all the operands of this instruction. If any of them become
/// dead, delete them and the computation tree that feeds them.
///
-static void DeleteDeadInstruction(Instruction *I, ScalarEvolution &SE) {
+static void deleteDeadInstruction(Instruction *I, ScalarEvolution &SE,
+ const TargetLibraryInfo *TLI) {
SmallVector<Instruction*, 32> NowDeadInsts;
-
+
NowDeadInsts.push_back(I);
-
+
// Before we touch this instruction, remove it from SE!
do {
Instruction *DeadInst = NowDeadInsts.pop_back_val();
-
+
// This instruction is dead, zap it, in stages. Start by removing it from
// SCEV.
SE.forgetValue(DeadInst);
-
+
for (unsigned op = 0, e = DeadInst->getNumOperands(); op != e; ++op) {
Value *Op = DeadInst->getOperand(op);
DeadInst->setOperand(op, 0);
-
+
// If this operand just became dead, add it to the NowDeadInsts list.
if (!Op->use_empty()) continue;
-
+
if (Instruction *OpI = dyn_cast<Instruction>(Op))
- if (isInstructionTriviallyDead(OpI))
+ if (isInstructionTriviallyDead(OpI, TLI))
NowDeadInsts.push_back(OpI);
}
-
+
DeadInst->eraseFromParent();
-
+
} while (!NowDeadInsts.empty());
}
+/// deleteIfDeadInstruction - If the specified value is a dead instruction,
+/// delete it and any recursively used instructions.
+static void deleteIfDeadInstruction(Value *V, ScalarEvolution &SE,
+ const TargetLibraryInfo *TLI) {
+ if (Instruction *I = dyn_cast<Instruction>(V))
+ if (isInstructionTriviallyDead(I, TLI))
+ deleteDeadInstruction(I, SE, TLI);
+}
+
bool LoopIdiomRecognize::runOnLoop(Loop *L, LPPassManager &LPM) {
CurLoop = L;
-
- // We only look at trivial single basic block loops.
- // TODO: eventually support more complex loops, scanning the header.
- if (L->getBlocks().size() != 1)
+
+ // If the loop could not be converted to canonical form, it must have an
+ // indirectbr in it, just give up.
+ if (!L->getLoopPreheader())
return false;
-
+
+ // Disable loop idiom recognition if the function's name is a common idiom.
+ StringRef Name = L->getHeader()->getParent()->getName();
+ if (Name == "memset" || Name == "memcpy")
+ return false;
+
// The trip count of the loop must be analyzable.
SE = &getAnalysis<ScalarEvolution>();
if (!SE->hasLoopInvariantBackedgeTakenCount(L))
return false;
const SCEV *BECount = SE->getBackedgeTakenCount(L);
if (isa<SCEVCouldNotCompute>(BECount)) return false;
-
+
+ // If this loop executes exactly one time, then it should be peeled, not
+ // optimized by this pass.
+ if (const SCEVConstant *BECst = dyn_cast<SCEVConstant>(BECount))
+ if (BECst->getValue()->getValue() == 0)
+ return false;
+
// We require target data for now.
- TD = getAnalysisIfAvailable<TargetData>();
+ TD = getAnalysisIfAvailable<DataLayout>();
if (TD == 0) return false;
-
- BasicBlock *BB = L->getHeader();
- DEBUG(dbgs() << "loop-idiom Scanning: F[" << BB->getParent()->getName()
- << "] Loop %" << BB->getName() << "\n");
+
+ DT = &getAnalysis<DominatorTree>();
+ LoopInfo &LI = getAnalysis<LoopInfo>();
+ TLI = &getAnalysis<TargetLibraryInfo>();
+
+ SmallVector<BasicBlock*, 8> ExitBlocks;
+ CurLoop->getUniqueExitBlocks(ExitBlocks);
+
+ DEBUG(dbgs() << "loop-idiom Scanning: F["
+ << L->getHeader()->getParent()->getName()
+ << "] Loop %" << L->getHeader()->getName() << "\n");
+
+ bool MadeChange = false;
+ // Scan all the blocks in the loop that are not in subloops.
+ for (Loop::block_iterator BI = L->block_begin(), E = L->block_end(); BI != E;
+ ++BI) {
+ // Ignore blocks in subloops.
+ if (LI.getLoopFor(*BI) != CurLoop)
+ continue;
+
+ MadeChange |= runOnLoopBlock(*BI, BECount, ExitBlocks);
+ }
+ return MadeChange;
+}
+
+/// runOnLoopBlock - Process the specified block, which lives in a counted loop
+/// with the specified backedge count. This block is known to be in the current
+/// loop and not in any subloops.
+bool LoopIdiomRecognize::runOnLoopBlock(BasicBlock *BB, const SCEV *BECount,
+ SmallVectorImpl<BasicBlock*> &ExitBlocks) {
+ // We can only promote stores in this block if they are unconditionally
+ // executed in the loop. For a block to be unconditionally executed, it has
+ // to dominate all the exit blocks of the loop. Verify this now.
+ for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i)
+ if (!DT->dominates(BB, ExitBlocks[i]))
+ return false;
bool MadeChange = false;
for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ) {
- // Look for store instructions, which may be memsets.
- StoreInst *SI = dyn_cast<StoreInst>(I++);
- if (SI == 0 || SI->isVolatile()) continue;
-
- WeakVH InstPtr(SI);
- if (!processLoopStore(SI, BECount)) continue;
-
- MadeChange = true;
-
- // If processing the store invalidated our iterator, start over from the
- // head of the loop.
- if (InstPtr == 0)
- I = BB->begin();
+ Instruction *Inst = I++;
+ // Look for store instructions, which may be optimized to memset/memcpy.
+ if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
+ WeakVH InstPtr(I);
+ if (!processLoopStore(SI, BECount)) continue;
+ MadeChange = true;
+
+ // If processing the store invalidated our iterator, start over from the
+ // top of the block.
+ if (InstPtr == 0)
+ I = BB->begin();
+ continue;
+ }
+
+ // Look for memset instructions, which may be optimized to a larger memset.
+ if (MemSetInst *MSI = dyn_cast<MemSetInst>(Inst)) {
+ WeakVH InstPtr(I);
+ if (!processLoopMemSet(MSI, BECount)) continue;
+ MadeChange = true;
+
+ // If processing the memset invalidated our iterator, start over from the
+ // top of the block.
+ if (InstPtr == 0)
+ I = BB->begin();
+ continue;
+ }
}
-
+
return MadeChange;
}
-/// scanBlock - Look over a block to see if we can promote anything out of it.
+
+/// processLoopStore - See if this store can be promoted to a memset or memcpy.
bool LoopIdiomRecognize::processLoopStore(StoreInst *SI, const SCEV *BECount) {
+ if (!SI->isSimple()) return false;
+
Value *StoredVal = SI->getValueOperand();
Value *StorePtr = SI->getPointerOperand();
-
+
// Reject stores that are so large that they overflow an unsigned.
uint64_t SizeInBits = TD->getTypeSizeInBits(StoredVal->getType());
if ((SizeInBits & 7) || (SizeInBits >> 32) != 0)
return false;
-
+
// See if the pointer expression is an AddRec like {base,+,1} on the current
// loop, which indicates a strided store. If we have something else, it's a
// random store we can't handle.
// Check to see if the stride matches the size of the store. If so, then we
// know that every byte is touched in the loop.
- unsigned StoreSize = (unsigned)SizeInBits >> 3;
+ unsigned StoreSize = (unsigned)SizeInBits >> 3;
const SCEVConstant *Stride = dyn_cast<SCEVConstant>(StoreEv->getOperand(1));
-
- // TODO: Could also handle negative stride here someday, that will require the
- // validity check in mayLoopModRefLocation to be updated though.
- if (Stride == 0 || StoreSize != Stride->getValue()->getValue())
+
+ if (Stride == 0 || StoreSize != Stride->getValue()->getValue()) {
+ // TODO: Could also handle negative stride here someday, that will require
+ // the validity check in mayLoopAccessLocation to be updated though.
+ // Enable this to print exact negative strides.
+ if (0 && Stride && StoreSize == -Stride->getValue()->getValue()) {
+ dbgs() << "NEGATIVE STRIDE: " << *SI << "\n";
+ dbgs() << "BB: " << *SI->getParent();
+ }
+
return false;
-
- // If the stored value is a byte-wise value (like i32 -1), then it may be
- // turned into a memset of i8 -1, assuming that all the consequtive bytes
- // are stored. A store of i32 0x01020304 can never be turned into a memset.
- if (Value *SplatValue = isBytewiseValue(StoredVal))
- if (processLoopStoreOfSplatValue(SI, StoreSize, SplatValue, StoreEv,
- BECount))
- return true;
+ }
+
+ // See if we can optimize just this store in isolation.
+ if (processLoopStridedStore(StorePtr, StoreSize, SI->getAlignment(),
+ StoredVal, SI, StoreEv, BECount))
+ return true;
// If the stored value is a strided load in the same loop with the same stride
// this this may be transformable into a memcpy. This kicks in for stuff like
const SCEVAddRecExpr *LoadEv =
dyn_cast<SCEVAddRecExpr>(SE->getSCEV(LI->getOperand(0)));
if (LoadEv && LoadEv->getLoop() == CurLoop && LoadEv->isAffine() &&
- StoreEv->getOperand(1) == LoadEv->getOperand(1) && !LI->isVolatile())
+ StoreEv->getOperand(1) == LoadEv->getOperand(1) && LI->isSimple())
if (processLoopStoreOfLoopLoad(SI, StoreSize, StoreEv, LoadEv, BECount))
return true;
}
- // errs() << "UNHANDLED strided store: " << *Ev << " - " << *SI << "\n";
+ //errs() << "UNHANDLED strided store: " << *StoreEv << " - " << *SI << "\n";
return false;
}
-/// mayLoopModRefLocation - Return true if the specified loop might do a load or
-/// store to the same location that the specified store could store to, which is
-/// a loop-strided access.
-static bool mayLoopModRefLocation(Value *Ptr, Loop *L, const SCEV *BECount,
+/// processLoopMemSet - See if this memset can be promoted to a large memset.
+bool LoopIdiomRecognize::
+processLoopMemSet(MemSetInst *MSI, const SCEV *BECount) {
+ // We can only handle non-volatile memsets with a constant size.
+ if (MSI->isVolatile() || !isa<ConstantInt>(MSI->getLength())) return false;
+
+ // If we're not allowed to hack on memset, we fail.
+ if (!TLI->has(LibFunc::memset))
+ return false;
+
+ Value *Pointer = MSI->getDest();
+
+ // See if the pointer expression is an AddRec like {base,+,1} on the current
+ // loop, which indicates a strided store. If we have something else, it's a
+ // random store we can't handle.
+ const SCEVAddRecExpr *Ev = dyn_cast<SCEVAddRecExpr>(SE->getSCEV(Pointer));
+ if (Ev == 0 || Ev->getLoop() != CurLoop || !Ev->isAffine())
+ return false;
+
+ // Reject memsets that are so large that they overflow an unsigned.
+ uint64_t SizeInBytes = cast<ConstantInt>(MSI->getLength())->getZExtValue();
+ if ((SizeInBytes >> 32) != 0)
+ return false;
+
+ // Check to see if the stride matches the size of the memset. If so, then we
+ // know that every byte is touched in the loop.
+ const SCEVConstant *Stride = dyn_cast<SCEVConstant>(Ev->getOperand(1));
+
+ // TODO: Could also handle negative stride here someday, that will require the
+ // validity check in mayLoopAccessLocation to be updated though.
+ if (Stride == 0 || MSI->getLength() != Stride->getValue())
+ return false;
+
+ return processLoopStridedStore(Pointer, (unsigned)SizeInBytes,
+ MSI->getAlignment(), MSI->getValue(),
+ MSI, Ev, BECount);
+}
+
+
+/// mayLoopAccessLocation - Return true if the specified loop might access the
+/// specified pointer location, which is a loop-strided access. The 'Access'
+/// argument specifies what the verboten forms of access are (read or write).
+static bool mayLoopAccessLocation(Value *Ptr,AliasAnalysis::ModRefResult Access,
+ Loop *L, const SCEV *BECount,
unsigned StoreSize, AliasAnalysis &AA,
- StoreInst *IgnoredStore) {
+ Instruction *IgnoredStore) {
// Get the location that may be stored across the loop. Since the access is
// strided positively through memory, we say that the modified location starts
// at the pointer and has infinite size.
// to be exactly the size of the memset, which is (BECount+1)*StoreSize
if (const SCEVConstant *BECst = dyn_cast<SCEVConstant>(BECount))
AccessSize = (BECst->getValue()->getZExtValue()+1)*StoreSize;
-
+
// TODO: For this to be really effective, we have to dive into the pointer
// operand in the store. Store to &A[i] of 100 will always return may alias
// with store of &A[100], we need to StoreLoc to be "A" with size of 100,
++BI)
for (BasicBlock::iterator I = (*BI)->begin(), E = (*BI)->end(); I != E; ++I)
if (&*I != IgnoredStore &&
- AA.getModRefInfo(I, StoreLoc) != AliasAnalysis::NoModRef)
+ (AA.getModRefInfo(I, StoreLoc) & Access))
return true;
return false;
}
-/// processLoopStoreOfSplatValue - We see a strided store of a memsetable value.
-/// If we can transform this into a memset in the loop preheader, do so.
+/// getMemSetPatternValue - If a strided store of the specified value is safe to
+/// turn into a memset_pattern16, return a ConstantArray of 16 bytes that should
+/// be passed in. Otherwise, return null.
+///
+/// Note that we don't ever attempt to use memset_pattern8 or 4, because these
+/// just replicate their input array and then pass on to memset_pattern16.
+static Constant *getMemSetPatternValue(Value *V, const DataLayout &TD) {
+ // If the value isn't a constant, we can't promote it to being in a constant
+ // array. We could theoretically do a store to an alloca or something, but
+ // that doesn't seem worthwhile.
+ Constant *C = dyn_cast<Constant>(V);
+ if (C == 0) return 0;
+
+ // Only handle simple values that are a power of two bytes in size.
+ uint64_t Size = TD.getTypeSizeInBits(V->getType());
+ if (Size == 0 || (Size & 7) || (Size & (Size-1)))
+ return 0;
+
+ // Don't care enough about darwin/ppc to implement this.
+ if (TD.isBigEndian())
+ return 0;
+
+ // Convert to size in bytes.
+ Size /= 8;
+
+ // TODO: If CI is larger than 16-bytes, we can try slicing it in half to see
+ // if the top and bottom are the same (e.g. for vectors and large integers).
+ if (Size > 16) return 0;
+
+ // If the constant is exactly 16 bytes, just use it.
+ if (Size == 16) return C;
+
+ // Otherwise, we'll use an array of the constants.
+ unsigned ArraySize = 16/Size;
+ ArrayType *AT = ArrayType::get(V->getType(), ArraySize);
+ return ConstantArray::get(AT, std::vector<Constant*>(ArraySize, C));
+}
+
+
+/// processLoopStridedStore - We see a strided store of some value. If we can
+/// transform this into a memset or memset_pattern in the loop preheader, do so.
bool LoopIdiomRecognize::
-processLoopStoreOfSplatValue(StoreInst *SI, unsigned StoreSize,
- Value *SplatValue,
- const SCEVAddRecExpr *Ev, const SCEV *BECount) {
- // Verify that the stored value is loop invariant. If not, we can't promote
- // the memset.
- if (!CurLoop->isLoopInvariant(SplatValue))
+processLoopStridedStore(Value *DestPtr, unsigned StoreSize,
+ unsigned StoreAlignment, Value *StoredVal,
+ Instruction *TheStore, const SCEVAddRecExpr *Ev,
+ const SCEV *BECount) {
+
+ // If the stored value is a byte-wise value (like i32 -1), then it may be
+ // turned into a memset of i8 -1, assuming that all the consecutive bytes
+ // are stored. A store of i32 0x01020304 can never be turned into a memset,
+ // but it can be turned into memset_pattern if the target supports it.
+ Value *SplatValue = isBytewiseValue(StoredVal);
+ 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 an alias.
- if (mayLoopModRefLocation(SI->getPointerOperand(), CurLoop, BECount,
- StoreSize, getAnalysis<AliasAnalysis>(), SI))
- return false;
-
- // Okay, everything looks good, insert the memset.
- BasicBlock *Preheader = CurLoop->getLoopPreheader();
-
- IRBuilder<> Builder(Preheader->getTerminator());
-
- // 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. Just insert code for it in the preheader.
- SCEVExpander Expander(*SE);
-
- unsigned AddrSpace = SI->getPointerAddressSpace();
- Value *BasePtr =
+ // 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, TLI);
+ 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.
- const Type *IntPtr = TD->getIntPtrType(SI->getContext());
- unsigned BESize = SE->getTypeSizeInBits(BECount->getType());
- if (BESize < TD->getPointerSizeInBits())
- BECount = SE->getZeroExtendExpr(BECount, IntPtr);
- else if (BESize > TD->getPointerSizeInBits())
- BECount = SE->getTruncateExpr(BECount, IntPtr);
-
+ Type *IntPtr = TD->getIntPtrType(DestPtr->getContext());
+ BECount = SE->getTruncateOrZeroExtend(BECount, IntPtr);
+
const SCEV *NumBytesS = SE->getAddExpr(BECount, SE->getConstant(IntPtr, 1),
- true, true /*nooverflow*/);
+ SCEV::FlagNUW);
if (StoreSize != 1)
NumBytesS = SE->getMulExpr(NumBytesS, SE->getConstant(IntPtr, StoreSize),
- true, true /*nooverflow*/);
-
- Value *NumBytes =
+ SCEV::FlagNUW);
+
+ Value *NumBytes =
Expander.expandCodeFor(NumBytesS, IntPtr, Preheader->getTerminator());
-
- Value *NewCall =
- Builder.CreateMemSet(BasePtr, SplatValue, NumBytes, SI->getAlignment());
-
+
+ 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: " << *SI << "\n");
- (void)NewCall;
-
+ << " 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(SI, *SE);
+ deleteDeadInstruction(TheStore, *SE, TLI);
+ ++NumMemSet;
return true;
}
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 memcmp in the loop preheader now if we want. However, this
+ // 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 to the aliased location (including the load feeding the stores).
- // Check for an alias.
- if (mayLoopModRefLocation(SI->getPointerOperand(), CurLoop, BECount,
- StoreSize, getAnalysis<AliasAnalysis>(), SI))
+ // 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, TLI);
return false;
-
- // Okay, everything looks good, insert the memcpy.
- BasicBlock *Preheader = CurLoop->getLoopPreheader();
-
- IRBuilder<> Builder(Preheader->getTerminator());
-
- // 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. Just insert code for it in the preheader.
- SCEVExpander Expander(*SE);
+ }
- Value *LoadBasePtr =
+ // 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());
- Value *StoreBasePtr =
- Expander.expandCodeFor(StoreEv->getStart(),
- Builder.getInt8PtrTy(SI->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, TLI);
+ deleteIfDeadInstruction(StoreBasePtr, *SE, TLI);
+ 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.
- const Type *IntPtr = TD->getIntPtrType(SI->getContext());
- unsigned BESize = SE->getTypeSizeInBits(BECount->getType());
- if (BESize < TD->getPointerSizeInBits())
- BECount = SE->getZeroExtendExpr(BECount, IntPtr);
- else if (BESize > TD->getPointerSizeInBits())
- BECount = SE->getTruncateExpr(BECount, IntPtr);
-
+ Type *IntPtr = TD->getIntPtrType(SI->getContext());
+ BECount = SE->getTruncateOrZeroExtend(BECount, IntPtr);
+
const SCEV *NumBytesS = SE->getAddExpr(BECount, SE->getConstant(IntPtr, 1),
- true, true /*nooverflow*/);
+ SCEV::FlagNUW);
if (StoreSize != 1)
NumBytesS = SE->getMulExpr(NumBytesS, SE->getConstant(IntPtr, StoreSize),
- true, true /*nooverflow*/);
-
+ SCEV::FlagNUW);
+
Value *NumBytes =
Expander.expandCodeFor(NumBytesS, IntPtr, Preheader->getTerminator());
-
- Value *NewCall =
+
+ 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");
- (void)NewCall;
-
+
+
// Okay, the memset has been formed. Zap the original store and anything that
// feeds into it.
- DeleteDeadInstruction(SI, *SE);
+ deleteDeadInstruction(SI, *SE, TLI);
+ ++NumMemCpy;
return true;
}
projects / oota-llvm.git / blobdiff