502 lines
21 KiB
C++
502 lines
21 KiB
C++
#include "llvm/Transforms/Utils/VNCoercion.h"
|
|
#include "llvm/Analysis/AliasAnalysis.h"
|
|
#include "llvm/Analysis/ConstantFolding.h"
|
|
#include "llvm/Analysis/MemoryDependenceAnalysis.h"
|
|
#include "llvm/Analysis/ValueTracking.h"
|
|
#include "llvm/IR/IRBuilder.h"
|
|
#include "llvm/IR/IntrinsicInst.h"
|
|
#include "llvm/Support/Debug.h"
|
|
|
|
#define DEBUG_TYPE "vncoerce"
|
|
namespace llvm {
|
|
namespace VNCoercion {
|
|
|
|
/// Return true if coerceAvailableValueToLoadType will succeed.
|
|
bool canCoerceMustAliasedValueToLoad(Value *StoredVal, Type *LoadTy,
|
|
const DataLayout &DL) {
|
|
// If the loaded or stored value is an first class array or struct, don't try
|
|
// to transform them. We need to be able to bitcast to integer.
|
|
if (LoadTy->isStructTy() || LoadTy->isArrayTy() ||
|
|
StoredVal->getType()->isStructTy() || StoredVal->getType()->isArrayTy())
|
|
return false;
|
|
|
|
uint64_t StoreSize = DL.getTypeSizeInBits(StoredVal->getType());
|
|
|
|
// The store size must be byte-aligned to support future type casts.
|
|
if (llvm::alignTo(StoreSize, 8) != StoreSize)
|
|
return false;
|
|
|
|
// The store has to be at least as big as the load.
|
|
if (StoreSize < DL.getTypeSizeInBits(LoadTy))
|
|
return false;
|
|
|
|
// Don't coerce non-integral pointers to integers or vice versa.
|
|
if (DL.isNonIntegralPointerType(StoredVal->getType()) !=
|
|
DL.isNonIntegralPointerType(LoadTy))
|
|
return false;
|
|
|
|
return true;
|
|
}
|
|
|
|
template <class T, class HelperClass>
|
|
static T *coerceAvailableValueToLoadTypeHelper(T *StoredVal, Type *LoadedTy,
|
|
HelperClass &Helper,
|
|
const DataLayout &DL) {
|
|
assert(canCoerceMustAliasedValueToLoad(StoredVal, LoadedTy, DL) &&
|
|
"precondition violation - materialization can't fail");
|
|
if (auto *C = dyn_cast<Constant>(StoredVal))
|
|
if (auto *FoldedStoredVal = ConstantFoldConstant(C, DL))
|
|
StoredVal = FoldedStoredVal;
|
|
|
|
// If this is already the right type, just return it.
|
|
Type *StoredValTy = StoredVal->getType();
|
|
|
|
uint64_t StoredValSize = DL.getTypeSizeInBits(StoredValTy);
|
|
uint64_t LoadedValSize = DL.getTypeSizeInBits(LoadedTy);
|
|
|
|
// If the store and reload are the same size, we can always reuse it.
|
|
if (StoredValSize == LoadedValSize) {
|
|
// Pointer to Pointer -> use bitcast.
|
|
if (StoredValTy->isPtrOrPtrVectorTy() && LoadedTy->isPtrOrPtrVectorTy()) {
|
|
StoredVal = Helper.CreateBitCast(StoredVal, LoadedTy);
|
|
} else {
|
|
// Convert source pointers to integers, which can be bitcast.
|
|
if (StoredValTy->isPtrOrPtrVectorTy()) {
|
|
StoredValTy = DL.getIntPtrType(StoredValTy);
|
|
StoredVal = Helper.CreatePtrToInt(StoredVal, StoredValTy);
|
|
}
|
|
|
|
Type *TypeToCastTo = LoadedTy;
|
|
if (TypeToCastTo->isPtrOrPtrVectorTy())
|
|
TypeToCastTo = DL.getIntPtrType(TypeToCastTo);
|
|
|
|
if (StoredValTy != TypeToCastTo)
|
|
StoredVal = Helper.CreateBitCast(StoredVal, TypeToCastTo);
|
|
|
|
// Cast to pointer if the load needs a pointer type.
|
|
if (LoadedTy->isPtrOrPtrVectorTy())
|
|
StoredVal = Helper.CreateIntToPtr(StoredVal, LoadedTy);
|
|
}
|
|
|
|
if (auto *C = dyn_cast<ConstantExpr>(StoredVal))
|
|
if (auto *FoldedStoredVal = ConstantFoldConstant(C, DL))
|
|
StoredVal = FoldedStoredVal;
|
|
|
|
return StoredVal;
|
|
}
|
|
// If the loaded value is smaller than the available value, then we can
|
|
// extract out a piece from it. If the available value is too small, then we
|
|
// can't do anything.
|
|
assert(StoredValSize >= LoadedValSize &&
|
|
"canCoerceMustAliasedValueToLoad fail");
|
|
|
|
// Convert source pointers to integers, which can be manipulated.
|
|
if (StoredValTy->isPtrOrPtrVectorTy()) {
|
|
StoredValTy = DL.getIntPtrType(StoredValTy);
|
|
StoredVal = Helper.CreatePtrToInt(StoredVal, StoredValTy);
|
|
}
|
|
|
|
// Convert vectors and fp to integer, which can be manipulated.
|
|
if (!StoredValTy->isIntegerTy()) {
|
|
StoredValTy = IntegerType::get(StoredValTy->getContext(), StoredValSize);
|
|
StoredVal = Helper.CreateBitCast(StoredVal, StoredValTy);
|
|
}
|
|
|
|
// If this is a big-endian system, we need to shift the value down to the low
|
|
// bits so that a truncate will work.
|
|
if (DL.isBigEndian()) {
|
|
uint64_t ShiftAmt = DL.getTypeStoreSizeInBits(StoredValTy) -
|
|
DL.getTypeStoreSizeInBits(LoadedTy);
|
|
StoredVal = Helper.CreateLShr(
|
|
StoredVal, ConstantInt::get(StoredVal->getType(), ShiftAmt));
|
|
}
|
|
|
|
// Truncate the integer to the right size now.
|
|
Type *NewIntTy = IntegerType::get(StoredValTy->getContext(), LoadedValSize);
|
|
StoredVal = Helper.CreateTruncOrBitCast(StoredVal, NewIntTy);
|
|
|
|
if (LoadedTy != NewIntTy) {
|
|
// If the result is a pointer, inttoptr.
|
|
if (LoadedTy->isPtrOrPtrVectorTy())
|
|
StoredVal = Helper.CreateIntToPtr(StoredVal, LoadedTy);
|
|
else
|
|
// Otherwise, bitcast.
|
|
StoredVal = Helper.CreateBitCast(StoredVal, LoadedTy);
|
|
}
|
|
|
|
if (auto *C = dyn_cast<Constant>(StoredVal))
|
|
if (auto *FoldedStoredVal = ConstantFoldConstant(C, DL))
|
|
StoredVal = FoldedStoredVal;
|
|
|
|
return StoredVal;
|
|
}
|
|
|
|
/// If we saw a store of a value to memory, and
|
|
/// then a load from a must-aliased pointer of a different type, try to coerce
|
|
/// the stored value. LoadedTy is the type of the load we want to replace.
|
|
/// IRB is IRBuilder used to insert new instructions.
|
|
///
|
|
/// If we can't do it, return null.
|
|
Value *coerceAvailableValueToLoadType(Value *StoredVal, Type *LoadedTy,
|
|
IRBuilder<> &IRB, const DataLayout &DL) {
|
|
return coerceAvailableValueToLoadTypeHelper(StoredVal, LoadedTy, IRB, DL);
|
|
}
|
|
|
|
/// This function is called when we have a memdep query of a load that ends up
|
|
/// being a clobbering memory write (store, memset, memcpy, memmove). This
|
|
/// means that the write *may* provide bits used by the load but we can't be
|
|
/// sure because the pointers don't must-alias.
|
|
///
|
|
/// 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 analyzeLoadFromClobberingWrite(Type *LoadTy, Value *LoadPtr,
|
|
Value *WritePtr,
|
|
uint64_t WriteSizeInBits,
|
|
const DataLayout &DL) {
|
|
// If the loaded or stored value is a first class array or struct, don't try
|
|
// to transform them. We need to be able to bitcast to integer.
|
|
if (LoadTy->isStructTy() || LoadTy->isArrayTy())
|
|
return -1;
|
|
|
|
int64_t StoreOffset = 0, LoadOffset = 0;
|
|
Value *StoreBase =
|
|
GetPointerBaseWithConstantOffset(WritePtr, StoreOffset, DL);
|
|
Value *LoadBase = GetPointerBaseWithConstantOffset(LoadPtr, LoadOffset, DL);
|
|
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. One case is forwarding a memset
|
|
// to a load from the base of the memset.
|
|
|
|
// 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.
|
|
uint64_t LoadSize = DL.getTypeSizeInBits(LoadTy);
|
|
|
|
if ((WriteSizeInBits & 7) | (LoadSize & 7))
|
|
return -1;
|
|
uint64_t StoreSize = WriteSizeInBits / 8; // Convert to bytes.
|
|
LoadSize /= 8;
|
|
|
|
bool isAAFailure = false;
|
|
if (StoreOffset < LoadOffset)
|
|
isAAFailure = StoreOffset + int64_t(StoreSize) <= LoadOffset;
|
|
else
|
|
isAAFailure = LoadOffset + int64_t(LoadSize) <= StoreOffset;
|
|
|
|
if (isAAFailure)
|
|
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;
|
|
}
|
|
|
|
/// This function is called when we have a
|
|
/// memdep query of a load that ends up being a clobbering store.
|
|
int analyzeLoadFromClobberingStore(Type *LoadTy, Value *LoadPtr,
|
|
StoreInst *DepSI, const DataLayout &DL) {
|
|
// Cannot handle reading from store of first-class aggregate yet.
|
|
if (DepSI->getValueOperand()->getType()->isStructTy() ||
|
|
DepSI->getValueOperand()->getType()->isArrayTy())
|
|
return -1;
|
|
|
|
Value *StorePtr = DepSI->getPointerOperand();
|
|
uint64_t StoreSize =
|
|
DL.getTypeSizeInBits(DepSI->getValueOperand()->getType());
|
|
return analyzeLoadFromClobberingWrite(LoadTy, LoadPtr, StorePtr, StoreSize,
|
|
DL);
|
|
}
|
|
|
|
/// This function is called when we have a
|
|
/// memdep query of a load that ends up being clobbered by another load. See if
|
|
/// the other load can feed into the second load.
|
|
int analyzeLoadFromClobberingLoad(Type *LoadTy, Value *LoadPtr, LoadInst *DepLI,
|
|
const DataLayout &DL) {
|
|
// Cannot handle reading from store of first-class aggregate yet.
|
|
if (DepLI->getType()->isStructTy() || DepLI->getType()->isArrayTy())
|
|
return -1;
|
|
|
|
Value *DepPtr = DepLI->getPointerOperand();
|
|
uint64_t DepSize = DL.getTypeSizeInBits(DepLI->getType());
|
|
int R = analyzeLoadFromClobberingWrite(LoadTy, LoadPtr, DepPtr, DepSize, DL);
|
|
if (R != -1)
|
|
return R;
|
|
|
|
// If we have a load/load clobber an DepLI can be widened to cover this load,
|
|
// then we should widen it!
|
|
int64_t LoadOffs = 0;
|
|
const Value *LoadBase =
|
|
GetPointerBaseWithConstantOffset(LoadPtr, LoadOffs, DL);
|
|
unsigned LoadSize = DL.getTypeStoreSize(LoadTy);
|
|
|
|
unsigned Size = MemoryDependenceResults::getLoadLoadClobberFullWidthSize(
|
|
LoadBase, LoadOffs, LoadSize, DepLI);
|
|
if (Size == 0)
|
|
return -1;
|
|
|
|
// Check non-obvious conditions enforced by MDA which we rely on for being
|
|
// able to materialize this potentially available value
|
|
assert(DepLI->isSimple() && "Cannot widen volatile/atomic load!");
|
|
assert(DepLI->getType()->isIntegerTy() && "Can't widen non-integer load");
|
|
|
|
return analyzeLoadFromClobberingWrite(LoadTy, LoadPtr, DepPtr, Size * 8, DL);
|
|
}
|
|
|
|
int analyzeLoadFromClobberingMemInst(Type *LoadTy, Value *LoadPtr,
|
|
MemIntrinsic *MI, const DataLayout &DL) {
|
|
// If the mem operation is a non-constant size, we can't handle it.
|
|
ConstantInt *SizeCst = dyn_cast<ConstantInt>(MI->getLength());
|
|
if (!SizeCst)
|
|
return -1;
|
|
uint64_t MemSizeInBits = SizeCst->getZExtValue() * 8;
|
|
|
|
// If this is memset, we just need to see if the offset is valid in the size
|
|
// of the memset..
|
|
if (MI->getIntrinsicID() == Intrinsic::memset)
|
|
return analyzeLoadFromClobberingWrite(LoadTy, LoadPtr, MI->getDest(),
|
|
MemSizeInBits, DL);
|
|
|
|
// If we have a memcpy/memmove, the only case we can handle is if this is a
|
|
// copy from constant memory. In that case, we can read directly from the
|
|
// constant memory.
|
|
MemTransferInst *MTI = cast<MemTransferInst>(MI);
|
|
|
|
Constant *Src = dyn_cast<Constant>(MTI->getSource());
|
|
if (!Src)
|
|
return -1;
|
|
|
|
GlobalVariable *GV = dyn_cast<GlobalVariable>(GetUnderlyingObject(Src, DL));
|
|
if (!GV || !GV->isConstant())
|
|
return -1;
|
|
|
|
// See if the access is within the bounds of the transfer.
|
|
int Offset = analyzeLoadFromClobberingWrite(LoadTy, LoadPtr, MI->getDest(),
|
|
MemSizeInBits, DL);
|
|
if (Offset == -1)
|
|
return Offset;
|
|
|
|
unsigned AS = Src->getType()->getPointerAddressSpace();
|
|
// Otherwise, see if we can constant fold a load from the constant with the
|
|
// offset applied as appropriate.
|
|
Src =
|
|
ConstantExpr::getBitCast(Src, Type::getInt8PtrTy(Src->getContext(), AS));
|
|
Constant *OffsetCst =
|
|
ConstantInt::get(Type::getInt64Ty(Src->getContext()), (unsigned)Offset);
|
|
Src = ConstantExpr::getGetElementPtr(Type::getInt8Ty(Src->getContext()), Src,
|
|
OffsetCst);
|
|
Src = ConstantExpr::getBitCast(Src, PointerType::get(LoadTy, AS));
|
|
if (ConstantFoldLoadFromConstPtr(Src, LoadTy, DL))
|
|
return Offset;
|
|
return -1;
|
|
}
|
|
|
|
template <class T, class HelperClass>
|
|
static T *getStoreValueForLoadHelper(T *SrcVal, unsigned Offset, Type *LoadTy,
|
|
HelperClass &Helper,
|
|
const DataLayout &DL) {
|
|
LLVMContext &Ctx = SrcVal->getType()->getContext();
|
|
|
|
// If two pointers are in the same address space, they have the same size,
|
|
// so we don't need to do any truncation, etc. This avoids introducing
|
|
// ptrtoint instructions for pointers that may be non-integral.
|
|
if (SrcVal->getType()->isPointerTy() && LoadTy->isPointerTy() &&
|
|
cast<PointerType>(SrcVal->getType())->getAddressSpace() ==
|
|
cast<PointerType>(LoadTy)->getAddressSpace()) {
|
|
return SrcVal;
|
|
}
|
|
|
|
uint64_t StoreSize = (DL.getTypeSizeInBits(SrcVal->getType()) + 7) / 8;
|
|
uint64_t LoadSize = (DL.getTypeSizeInBits(LoadTy) + 7) / 8;
|
|
// Compute which bits of the stored value are being used by the load. Convert
|
|
// to an integer type to start with.
|
|
if (SrcVal->getType()->isPtrOrPtrVectorTy())
|
|
SrcVal = Helper.CreatePtrToInt(SrcVal, DL.getIntPtrType(SrcVal->getType()));
|
|
if (!SrcVal->getType()->isIntegerTy())
|
|
SrcVal = Helper.CreateBitCast(SrcVal, IntegerType::get(Ctx, StoreSize * 8));
|
|
|
|
// Shift the bits to the least significant depending on endianness.
|
|
unsigned ShiftAmt;
|
|
if (DL.isLittleEndian())
|
|
ShiftAmt = Offset * 8;
|
|
else
|
|
ShiftAmt = (StoreSize - LoadSize - Offset) * 8;
|
|
if (ShiftAmt)
|
|
SrcVal = Helper.CreateLShr(SrcVal,
|
|
ConstantInt::get(SrcVal->getType(), ShiftAmt));
|
|
|
|
if (LoadSize != StoreSize)
|
|
SrcVal = Helper.CreateTruncOrBitCast(SrcVal,
|
|
IntegerType::get(Ctx, LoadSize * 8));
|
|
return SrcVal;
|
|
}
|
|
|
|
/// 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 provides bits used by
|
|
/// the load but the pointers don't must-alias. Check this case to see if
|
|
/// there is anything more we can do before we give up.
|
|
Value *getStoreValueForLoad(Value *SrcVal, unsigned Offset, Type *LoadTy,
|
|
Instruction *InsertPt, const DataLayout &DL) {
|
|
|
|
IRBuilder<> Builder(InsertPt);
|
|
SrcVal = getStoreValueForLoadHelper(SrcVal, Offset, LoadTy, Builder, DL);
|
|
return coerceAvailableValueToLoadTypeHelper(SrcVal, LoadTy, Builder, DL);
|
|
}
|
|
|
|
Constant *getConstantStoreValueForLoad(Constant *SrcVal, unsigned Offset,
|
|
Type *LoadTy, const DataLayout &DL) {
|
|
ConstantFolder F;
|
|
SrcVal = getStoreValueForLoadHelper(SrcVal, Offset, LoadTy, F, DL);
|
|
return coerceAvailableValueToLoadTypeHelper(SrcVal, LoadTy, F, DL);
|
|
}
|
|
|
|
/// This function is called when we have a memdep query of a load that ends up
|
|
/// being a clobbering load. This means that the load *may* provide bits used
|
|
/// by the load but we can't be sure because the pointers don't must-alias.
|
|
/// Check this case to see if there is anything more we can do before we give
|
|
/// up.
|
|
Value *getLoadValueForLoad(LoadInst *SrcVal, unsigned Offset, Type *LoadTy,
|
|
Instruction *InsertPt, const DataLayout &DL) {
|
|
// If Offset+LoadTy exceeds the size of SrcVal, then we must be wanting to
|
|
// widen SrcVal out to a larger load.
|
|
unsigned SrcValStoreSize = DL.getTypeStoreSize(SrcVal->getType());
|
|
unsigned LoadSize = DL.getTypeStoreSize(LoadTy);
|
|
if (Offset + LoadSize > SrcValStoreSize) {
|
|
assert(SrcVal->isSimple() && "Cannot widen volatile/atomic load!");
|
|
assert(SrcVal->getType()->isIntegerTy() && "Can't widen non-integer load");
|
|
// If we have a load/load clobber an DepLI can be widened to cover this
|
|
// load, then we should widen it to the next power of 2 size big enough!
|
|
unsigned NewLoadSize = Offset + LoadSize;
|
|
if (!isPowerOf2_32(NewLoadSize))
|
|
NewLoadSize = NextPowerOf2(NewLoadSize);
|
|
|
|
Value *PtrVal = SrcVal->getPointerOperand();
|
|
// Insert the new load after the old load. This ensures that subsequent
|
|
// memdep queries will find the new load. We can't easily remove the old
|
|
// load completely because it is already in the value numbering table.
|
|
IRBuilder<> Builder(SrcVal->getParent(), ++BasicBlock::iterator(SrcVal));
|
|
Type *DestPTy = IntegerType::get(LoadTy->getContext(), NewLoadSize * 8);
|
|
DestPTy =
|
|
PointerType::get(DestPTy, PtrVal->getType()->getPointerAddressSpace());
|
|
Builder.SetCurrentDebugLocation(SrcVal->getDebugLoc());
|
|
PtrVal = Builder.CreateBitCast(PtrVal, DestPTy);
|
|
LoadInst *NewLoad = Builder.CreateLoad(PtrVal);
|
|
NewLoad->takeName(SrcVal);
|
|
NewLoad->setAlignment(SrcVal->getAlignment());
|
|
|
|
LLVM_DEBUG(dbgs() << "GVN WIDENED LOAD: " << *SrcVal << "\n");
|
|
LLVM_DEBUG(dbgs() << "TO: " << *NewLoad << "\n");
|
|
|
|
// Replace uses of the original load with the wider load. On a big endian
|
|
// system, we need to shift down to get the relevant bits.
|
|
Value *RV = NewLoad;
|
|
if (DL.isBigEndian())
|
|
RV = Builder.CreateLShr(RV, (NewLoadSize - SrcValStoreSize) * 8);
|
|
RV = Builder.CreateTrunc(RV, SrcVal->getType());
|
|
SrcVal->replaceAllUsesWith(RV);
|
|
|
|
SrcVal = NewLoad;
|
|
}
|
|
|
|
return getStoreValueForLoad(SrcVal, Offset, LoadTy, InsertPt, DL);
|
|
}
|
|
|
|
Constant *getConstantLoadValueForLoad(Constant *SrcVal, unsigned Offset,
|
|
Type *LoadTy, const DataLayout &DL) {
|
|
unsigned SrcValStoreSize = DL.getTypeStoreSize(SrcVal->getType());
|
|
unsigned LoadSize = DL.getTypeStoreSize(LoadTy);
|
|
if (Offset + LoadSize > SrcValStoreSize)
|
|
return nullptr;
|
|
return getConstantStoreValueForLoad(SrcVal, Offset, LoadTy, DL);
|
|
}
|
|
|
|
template <class T, class HelperClass>
|
|
T *getMemInstValueForLoadHelper(MemIntrinsic *SrcInst, unsigned Offset,
|
|
Type *LoadTy, HelperClass &Helper,
|
|
const DataLayout &DL) {
|
|
LLVMContext &Ctx = LoadTy->getContext();
|
|
uint64_t LoadSize = DL.getTypeSizeInBits(LoadTy) / 8;
|
|
|
|
// We know that this method is only called when the mem transfer fully
|
|
// provides the bits for the load.
|
|
if (MemSetInst *MSI = dyn_cast<MemSetInst>(SrcInst)) {
|
|
// memset(P, 'x', 1234) -> splat('x'), even if x is a variable, and
|
|
// independently of what the offset is.
|
|
T *Val = cast<T>(MSI->getValue());
|
|
if (LoadSize != 1)
|
|
Val =
|
|
Helper.CreateZExtOrBitCast(Val, IntegerType::get(Ctx, LoadSize * 8));
|
|
T *OneElt = Val;
|
|
|
|
// Splat the value out to the right number of bits.
|
|
for (unsigned NumBytesSet = 1; NumBytesSet != LoadSize;) {
|
|
// If we can double the number of bytes set, do it.
|
|
if (NumBytesSet * 2 <= LoadSize) {
|
|
T *ShVal = Helper.CreateShl(
|
|
Val, ConstantInt::get(Val->getType(), NumBytesSet * 8));
|
|
Val = Helper.CreateOr(Val, ShVal);
|
|
NumBytesSet <<= 1;
|
|
continue;
|
|
}
|
|
|
|
// Otherwise insert one byte at a time.
|
|
T *ShVal = Helper.CreateShl(Val, ConstantInt::get(Val->getType(), 1 * 8));
|
|
Val = Helper.CreateOr(OneElt, ShVal);
|
|
++NumBytesSet;
|
|
}
|
|
|
|
return coerceAvailableValueToLoadTypeHelper(Val, LoadTy, Helper, DL);
|
|
}
|
|
|
|
// Otherwise, this is a memcpy/memmove from a constant global.
|
|
MemTransferInst *MTI = cast<MemTransferInst>(SrcInst);
|
|
Constant *Src = cast<Constant>(MTI->getSource());
|
|
unsigned AS = Src->getType()->getPointerAddressSpace();
|
|
|
|
// Otherwise, see if we can constant fold a load from the constant with the
|
|
// offset applied as appropriate.
|
|
Src =
|
|
ConstantExpr::getBitCast(Src, Type::getInt8PtrTy(Src->getContext(), AS));
|
|
Constant *OffsetCst =
|
|
ConstantInt::get(Type::getInt64Ty(Src->getContext()), (unsigned)Offset);
|
|
Src = ConstantExpr::getGetElementPtr(Type::getInt8Ty(Src->getContext()), Src,
|
|
OffsetCst);
|
|
Src = ConstantExpr::getBitCast(Src, PointerType::get(LoadTy, AS));
|
|
return ConstantFoldLoadFromConstPtr(Src, LoadTy, DL);
|
|
}
|
|
|
|
/// This function is called when we have a
|
|
/// memdep query of a load that ends up being a clobbering mem intrinsic.
|
|
Value *getMemInstValueForLoad(MemIntrinsic *SrcInst, unsigned Offset,
|
|
Type *LoadTy, Instruction *InsertPt,
|
|
const DataLayout &DL) {
|
|
IRBuilder<> Builder(InsertPt);
|
|
return getMemInstValueForLoadHelper<Value, IRBuilder<>>(SrcInst, Offset,
|
|
LoadTy, Builder, DL);
|
|
}
|
|
|
|
Constant *getConstantMemInstValueForLoad(MemIntrinsic *SrcInst, unsigned Offset,
|
|
Type *LoadTy, const DataLayout &DL) {
|
|
// The only case analyzeLoadFromClobberingMemInst cannot be converted to a
|
|
// constant is when it's a memset of a non-constant.
|
|
if (auto *MSI = dyn_cast<MemSetInst>(SrcInst))
|
|
if (!isa<Constant>(MSI->getValue()))
|
|
return nullptr;
|
|
ConstantFolder F;
|
|
return getMemInstValueForLoadHelper<Constant, ConstantFolder>(SrcInst, Offset,
|
|
LoadTy, F, DL);
|
|
}
|
|
} // namespace VNCoercion
|
|
} // namespace llvm
|