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move some functions, add a comment.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82444 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2009-09-21 06:24:16 +00:00
parent 1ce0829e83
commit ca74940fee
1 changed files with 165 additions and 164 deletions
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329
lib/Transforms/Scalar/GVN.cpp
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@ -1022,9 +1022,173 @@ static Value *CoerceAvailableValueToLoadType(Value *StoredVal,
return new BitCastInst(StoredVal, LoadedTy, "bitcast", InsertPt);
}
/// GetBaseWithConstantOffset - Analyze the specified pointer to see if it can
/// be expressed as a base pointer plus a constant offset. Return the base and
/// offset to the caller.
static Value *GetBaseWithConstantOffset(Value *Ptr, int64_t &Offset,
const TargetData *TD) {
Operator *PtrOp = dyn_cast<Operator>(Ptr);
if (PtrOp == 0) return Ptr;
// Just look through bitcasts.
if (PtrOp->getOpcode() == Instruction::BitCast)
return GetBaseWithConstantOffset(PtrOp->getOperand(0), Offset, TD);
// If this is a GEP with constant indices, we can look through it.
GEPOperator *GEP = dyn_cast<GEPOperator>(PtrOp);
if (GEP == 0 || !GEP->hasAllConstantIndices()) return Ptr;
gep_type_iterator GTI = gep_type_begin(GEP);
for (User::op_iterator I = GEP->idx_begin(), E = GEP->idx_end(); I != E;
++I, ++GTI) {
ConstantInt *OpC = cast<ConstantInt>(*I);
if (OpC->isZero()) continue;
// Handle a struct and array indices which add their offset to the pointer.
if (const StructType *STy = dyn_cast<StructType>(*GTI)) {
Offset += TD->getStructLayout(STy)->getElementOffset(OpC->getZExtValue());
} else {
uint64_t Size = TD->getTypeAllocSize(GTI.getIndexedType());
Offset += OpC->getSExtValue()*Size;
}
}
// Re-sign extend from the pointer size if needed to get overflow edge cases
// right.
unsigned PtrSize = TD->getPointerSizeInBits();
if (PtrSize < 64)
Offset = (Offset << (64-PtrSize)) >> (64-PtrSize);
return GetBaseWithConstantOffset(GEP->getPointerOperand(), Offset, TD);
}
/// AnalyzeLoadFromClobberingStore - This function is called when we have a
/// memdep query of a load that ends up being a clobbering store. This means
/// that the store *may* provide bits used by the load but we can't be sure
/// because the pointers don't mustalias. Check this case to see if there is
/// anything more we can do before we give up. This returns -1 if we have to
/// give up, or a byte number in the stored value of the piece that feeds the
/// load.
static int AnalyzeLoadFromClobberingStore(LoadInst *L, StoreInst *DepSI,
const TargetData *TD) {
int64_t StoreOffset = 0, LoadOffset = 0;
Value *StoreBase =
GetBaseWithConstantOffset(DepSI->getPointerOperand(), StoreOffset, TD);
Value *LoadBase =
GetBaseWithConstantOffset(L->getPointerOperand(), LoadOffset, TD);
if (StoreBase != LoadBase)
return -1;
// If the load and store are to the exact same address, they should have been
// a must alias. AA must have gotten confused.
// FIXME: Study to see if/when this happens.
if (LoadOffset == StoreOffset) {
#if 0
errs() << "STORE/LOAD DEP WITH COMMON POINTER MISSED:\n"
<< "Base = " << *StoreBase << "\n"
<< "Store Ptr = " << *DepSI->getPointerOperand() << "\n"
<< "Store Offs = " << StoreOffset << " - " << *DepSI << "\n"
<< "Load Ptr = " << *L->getPointerOperand() << "\n"
<< "Load Offs = " << LoadOffset << " - " << *L << "\n\n";
errs() << "'" << L->getParent()->getParent()->getName() << "'"
<< *L->getParent();
#endif
return -1;
}
// If the load and store don't overlap at all, the store doesn't provide
// anything to the load. In this case, they really don't alias at all, AA
// must have gotten confused.
// FIXME: Investigate cases where this bails out, e.g. rdar://7238614. Then
// remove this check, as it is duplicated with what we have below.
uint64_t StoreSize = TD->getTypeSizeInBits(DepSI->getOperand(0)->getType());
uint64_t LoadSize = TD->getTypeSizeInBits(L->getType());
if ((StoreSize & 7) | (LoadSize & 7))
return -1;
StoreSize >>= 3; // Convert to bytes.
LoadSize >>= 3;
bool isAAFailure = false;
if (StoreOffset < LoadOffset) {
isAAFailure = StoreOffset+int64_t(StoreSize) <= LoadOffset;
} else {
isAAFailure = LoadOffset+int64_t(LoadSize) <= StoreOffset;
}
if (isAAFailure) {
#if 0
errs() << "STORE LOAD DEP WITH COMMON BASE:\n"
<< "Base = " << *StoreBase << "\n"
<< "Store Ptr = " << *DepSI->getPointerOperand() << "\n"
<< "Store Offs = " << StoreOffset << " - " << *DepSI << "\n"
<< "Load Ptr = " << *L->getPointerOperand() << "\n"
<< "Load Offs = " << LoadOffset << " - " << *L << "\n\n";
errs() << "'" << L->getParent()->getParent()->getName() << "'"
<< *L->getParent();
#endif
return -1;
}
// If the Load isn't completely contained within the stored bits, we don't
// have all the bits to feed it. We could do something crazy in the future
// (issue a smaller load then merge the bits in) but this seems unlikely to be
// valuable.
if (StoreOffset > LoadOffset ||
StoreOffset+StoreSize < LoadOffset+LoadSize)
return -1;
// Okay, we can do this transformation. Return the number of bytes into the
// store that the load is.
return LoadOffset-StoreOffset;
}
/// GetStoreValueForLoad - This function is called when we have a
/// memdep query of a load that ends up being a clobbering store. This means
/// that the store *may* provide bits used by the load but we can't be sure
/// because the pointers don't mustalias. Check this case to see if there is
/// anything more we can do before we give up.
static Value *GetStoreValueForLoad(Value *SrcVal, int Offset,const Type *LoadTy,
Instruction *InsertPt, const TargetData *TD){
LLVMContext &Ctx = SrcVal->getType()->getContext();
uint64_t StoreSize = TD->getTypeSizeInBits(SrcVal->getType())/8;
uint64_t LoadSize = TD->getTypeSizeInBits(LoadTy)/8;
// Compute which bits of the stored value are being used by the load. Convert
// to an integer type to start with.
if (isa<PointerType>(SrcVal->getType()))
SrcVal = new PtrToIntInst(SrcVal, TD->getIntPtrType(Ctx), "tmp", InsertPt);
if (!isa<IntegerType>(SrcVal->getType()))
SrcVal = new BitCastInst(SrcVal, IntegerType::get(Ctx, StoreSize*8),
"tmp", InsertPt);
// Shift the bits to the least significant depending on endianness.
unsigned ShiftAmt;
if (TD->isLittleEndian()) {
ShiftAmt = Offset*8;
} else {
ShiftAmt = StoreSize-LoadSize-Offset;
}
SrcVal = BinaryOperator::CreateLShr(SrcVal,
ConstantInt::get(SrcVal->getType(), ShiftAmt), "tmp", InsertPt);
SrcVal = new TruncInst(SrcVal, IntegerType::get(Ctx, LoadSize*8),
"tmp", InsertPt);
return CoerceAvailableValueToLoadType(SrcVal, LoadTy, InsertPt, *TD);
}
/// GetAvailableBlockValues - Given the ValuesPerBlock list, convert all of the
/// available values to values of the expected LoadTy in their blocks and insert
/// the new values into BlockReplValues.
static void
GetAvailableBlockValues(DenseMap<BasicBlock*, Value*> &BlockReplValues,
SmallVector<std::pair<BasicBlock*,
const SmallVector<std::pair<BasicBlock*,
Value*>, 16> &ValuesPerBlock,
const Type *LoadTy,
const TargetData *TD) {
@ -1343,169 +1507,6 @@ bool GVN::processNonLocalLoad(LoadInst *LI,
return true;
}
/// GetBaseWithConstantOffset - Analyze the specified pointer to see if it can
/// be expressed as a base pointer plus a constant offset. Return the base and
/// offset to the caller.
static Value *GetBaseWithConstantOffset(Value *Ptr, int64_t &Offset,
const TargetData *TD) {
Operator *PtrOp = dyn_cast<Operator>(Ptr);
if (PtrOp == 0) return Ptr;
// Just look through bitcasts.
if (PtrOp->getOpcode() == Instruction::BitCast)
return GetBaseWithConstantOffset(PtrOp->getOperand(0), Offset, TD);
// If this is a GEP with constant indices, we can look through it.
GEPOperator *GEP = dyn_cast<GEPOperator>(PtrOp);
if (GEP == 0 || !GEP->hasAllConstantIndices()) return Ptr;
gep_type_iterator GTI = gep_type_begin(GEP);
for (User::op_iterator I = GEP->idx_begin(), E = GEP->idx_end(); I != E;
++I, ++GTI) {
ConstantInt *OpC = cast<ConstantInt>(*I);
if (OpC->isZero()) continue;
// Handle a struct and array indices which add their offset to the pointer.
if (const StructType *STy = dyn_cast<StructType>(*GTI)) {
Offset += TD->getStructLayout(STy)->getElementOffset(OpC->getZExtValue());
} else {
uint64_t Size = TD->getTypeAllocSize(GTI.getIndexedType());
Offset += OpC->getSExtValue()*Size;
}
}
// Re-sign extend from the pointer size if needed to get overflow edge cases
// right.
unsigned PtrSize = TD->getPointerSizeInBits();
if (PtrSize < 64)
Offset = (Offset << (64-PtrSize)) >> (64-PtrSize);
return GetBaseWithConstantOffset(GEP->getPointerOperand(), Offset, TD);
}
/// AnalyzeLoadFromClobberingStore - This function is called when we have a
/// memdep query of a load that ends up being a clobbering store. This means
/// that the store *may* provide bits used by the load but we can't be sure
/// because the pointers don't mustalias. Check this case to see if there is
/// anything more we can do before we give up. This returns -1 if we have to
/// give up, or a byte number in the stored value of the piece that feeds the
/// load.
static int AnalyzeLoadFromClobberingStore(LoadInst *L, StoreInst *DepSI,
const TargetData *TD) {
int64_t StoreOffset = 0, LoadOffset = 0;
Value *StoreBase =
GetBaseWithConstantOffset(DepSI->getPointerOperand(), StoreOffset, TD);
Value *LoadBase =
GetBaseWithConstantOffset(L->getPointerOperand(), LoadOffset, TD);
if (StoreBase != LoadBase)
return -1;
// If the load and store are to the exact same address, they should have been
// a must alias. AA must have gotten confused.
// FIXME: Study to see if/when this happens.
if (LoadOffset == StoreOffset) {
#if 0
errs() << "STORE/LOAD DEP WITH COMMON POINTER MISSED:\n"
<< "Base = " << *StoreBase << "\n"
<< "Store Ptr = " << *DepSI->getPointerOperand() << "\n"
<< "Store Offs = " << StoreOffset << " - " << *DepSI << "\n"
<< "Load Ptr = " << *L->getPointerOperand() << "\n"
<< "Load Offs = " << LoadOffset << " - " << *L << "\n\n";
errs() << "'" << L->getParent()->getParent()->getName() << "'"
<< *L->getParent();
#endif
return -1;
}
// If the load and store don't overlap at all, the store doesn't provide
// anything to the load. In this case, they really don't alias at all, AA
// must have gotten confused.
// FIXME: Investigate cases where this bails out, e.g. rdar://7238614. Then
// remove this check, as it is duplicated with what we have below.
uint64_t StoreSize = TD->getTypeSizeInBits(DepSI->getOperand(0)->getType());
uint64_t LoadSize = TD->getTypeSizeInBits(L->getType());
if ((StoreSize & 7) | (LoadSize & 7))
return -1;
StoreSize >>= 3; // Convert to bytes.
LoadSize >>= 3;
bool isAAFailure = false;
if (StoreOffset < LoadOffset) {
isAAFailure = StoreOffset+int64_t(StoreSize) <= LoadOffset;
} else {
isAAFailure = LoadOffset+int64_t(LoadSize) <= StoreOffset;
}
if (isAAFailure) {
#if 0
errs() << "STORE LOAD DEP WITH COMMON BASE:\n"
<< "Base = " << *StoreBase << "\n"
<< "Store Ptr = " << *DepSI->getPointerOperand() << "\n"
<< "Store Offs = " << StoreOffset << " - " << *DepSI << "\n"
<< "Load Ptr = " << *L->getPointerOperand() << "\n"
<< "Load Offs = " << LoadOffset << " - " << *L << "\n\n";
errs() << "'" << L->getParent()->getParent()->getName() << "'"
<< *L->getParent();
#endif
return -1;
}
// If the Load isn't completely contained within the stored bits, we don't
// have all the bits to feed it. We could do something crazy in the future
// (issue a smaller load then merge the bits in) but this seems unlikely to be
// valuable.
if (StoreOffset > LoadOffset ||
StoreOffset+StoreSize < LoadOffset+LoadSize)
return -1;
// Okay, we can do this transformation. Return the number of bytes into the
// store that the load is.
return LoadOffset-StoreOffset;
}
/// GetStoreValueForLoad - This function is called when we have a
/// memdep query of a load that ends up being a clobbering store. This means
/// that the store *may* provide bits used by the load but we can't be sure
/// because the pointers don't mustalias. Check this case to see if there is
/// anything more we can do before we give up.
static Value *GetStoreValueForLoad(Value *SrcVal, int Offset,const Type *LoadTy,
Instruction *InsertPt, const TargetData *TD){
LLVMContext &Ctx = SrcVal->getType()->getContext();
uint64_t StoreSize = TD->getTypeSizeInBits(SrcVal->getType())/8;
uint64_t LoadSize = TD->getTypeSizeInBits(LoadTy)/8;
// Compute which bits of the stored value are being used by the load. Convert
// to an integer type to start with.
if (isa<PointerType>(SrcVal->getType()))
SrcVal = new PtrToIntInst(SrcVal, TD->getIntPtrType(Ctx), "tmp", InsertPt);
if (!isa<IntegerType>(SrcVal->getType()))
SrcVal = new BitCastInst(SrcVal, IntegerType::get(Ctx, StoreSize*8),
"tmp", InsertPt);
// Shift the bits to the least significant depending on endianness.
unsigned ShiftAmt;
if (TD->isLittleEndian()) {
ShiftAmt = Offset*8;
} else {
ShiftAmt = StoreSize-LoadSize-Offset;
}
SrcVal = BinaryOperator::CreateLShr(SrcVal,
ConstantInt::get(SrcVal->getType(), ShiftAmt), "tmp", InsertPt);
SrcVal = new TruncInst(SrcVal, IntegerType::get(Ctx, LoadSize*8),
"tmp", InsertPt);
return CoerceAvailableValueToLoadType(SrcVal, LoadTy, InsertPt, *TD);
}
/// processLoad - Attempt to eliminate a load, first by eliminating it
/// locally, and then attempting non-local elimination if that fails.
bool GVN::processLoad(LoadInst *L, SmallVectorImpl<Instruction*> &toErase) {