pull all the ConvertToScalarInfo code together into one
place.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@101427 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/ScalarReplAggregates.cpp b/lib/Transforms/Scalar/ScalarReplAggregates.cpp
index 1ca0e91..0731d51 100644
--- a/lib/Transforms/Scalar/ScalarReplAggregates.cpp
+++ b/lib/Transforms/Scalar/ScalarReplAggregates.cpp
@@ -49,8 +49,6 @@
STATISTIC(NumGlobals, "Number of allocas copied from constant global");
namespace {
- struct ConvertToScalarInfo;
-
struct SROA : public FunctionPass {
static char ID; // Pass identification, replacement for typeid
explicit SROA(signed T = -1) : FunctionPass(&ID) {
@@ -145,6 +143,573 @@
}
+//===----------------------------------------------------------------------===//
+// Convert To Scalar Optimization.
+//===----------------------------------------------------------------------===//
+
+namespace {
+/// ConvertToScalarInfo - This struct is used by CanConvertToScalar
+class ConvertToScalarInfo {
+ /// AllocaSize - The size of the alloca being considered.
+ unsigned AllocaSize;
+ const TargetData &TD;
+
+ bool IsNotTrivial;
+ const Type *VectorTy;
+ bool HadAVector;
+
+public:
+ explicit ConvertToScalarInfo(unsigned Size, const TargetData &td)
+ : AllocaSize(Size), TD(td) {
+ IsNotTrivial = false;
+ VectorTy = 0;
+ HadAVector = false;
+ }
+
+ AllocaInst *TryConvert(AllocaInst *AI) {
+ // If we can't convert this scalar, or if mem2reg can trivially do it, bail
+ // out.
+ if (!CanConvertToScalar(AI, 0) || !IsNotTrivial)
+ // FIXME: In the trivial case, just use mem2reg.
+ return 0;
+
+ // If we were able to find a vector type that can handle this with
+ // insert/extract elements, and if there was at least one use that had
+ // a vector type, promote this to a vector. We don't want to promote
+ // random stuff that doesn't use vectors (e.g. <9 x double>) because then
+ // we just get a lot of insert/extracts. If at least one vector is
+ // involved, then we probably really do have a union of vector/array.
+ const Type *NewTy;
+ if (VectorTy && VectorTy->isVectorTy() && HadAVector) {
+ DEBUG(dbgs() << "CONVERT TO VECTOR: " << *AI << "\n TYPE = "
+ << *VectorTy << '\n');
+ NewTy = VectorTy; // Use the vector type.
+ } else {
+ DEBUG(dbgs() << "CONVERT TO SCALAR INTEGER: " << *AI << "\n");
+ // Create and insert the integer alloca.
+ NewTy = IntegerType::get(AI->getContext(), AllocaSize*8);
+ }
+ AllocaInst *NewAI = new AllocaInst(NewTy, 0, "", AI->getParent()->begin());
+ ConvertUsesToScalar(AI, NewAI, 0);
+ return NewAI;
+ }
+
+private:
+ bool CanConvertToScalar(Value *V, uint64_t Offset);
+ void MergeInType(const Type *In, uint64_t Offset);
+ void ConvertUsesToScalar(Value *Ptr, AllocaInst *NewAI, uint64_t Offset);
+
+ Value *ConvertScalar_ExtractValue(Value *NV, const Type *ToType,
+ uint64_t Offset, IRBuilder<> &Builder);
+ Value *ConvertScalar_InsertValue(Value *StoredVal, Value *ExistingVal,
+ uint64_t Offset, IRBuilder<> &Builder);
+};
+} // end anonymous namespace.
+
+/// MergeInType - Add the 'In' type to the accumulated type (Accum) so far at
+/// the offset specified by Offset (which is specified in bytes).
+///
+/// There are two cases we handle here:
+/// 1) A union of vector types of the same size and potentially its elements.
+/// Here we turn element accesses into insert/extract element operations.
+/// This promotes a <4 x float> with a store of float to the third element
+/// into a <4 x float> that uses insert element.
+/// 2) A fully general blob of memory, which we turn into some (potentially
+/// large) integer type with extract and insert operations where the loads
+/// and stores would mutate the memory.
+void ConvertToScalarInfo::MergeInType(const Type *In, uint64_t Offset) {
+ // Remember if we saw a vector type.
+ HadAVector |= In->isVectorTy();
+
+ if (VectorTy && VectorTy->isVoidTy())
+ return;
+
+ // If this could be contributing to a vector, analyze it.
+
+ // If the In type is a vector that is the same size as the alloca, see if it
+ // matches the existing VecTy.
+ if (const VectorType *VInTy = dyn_cast<VectorType>(In)) {
+ if (VInTy->getBitWidth()/8 == AllocaSize && Offset == 0) {
+ // If we're storing/loading a vector of the right size, allow it as a
+ // vector. If this the first vector we see, remember the type so that
+ // we know the element size.
+ if (VectorTy == 0)
+ VectorTy = VInTy;
+ return;
+ }
+ } else if (In->isFloatTy() || In->isDoubleTy() ||
+ (In->isIntegerTy() && In->getPrimitiveSizeInBits() >= 8 &&
+ isPowerOf2_32(In->getPrimitiveSizeInBits()))) {
+ // If we're accessing something that could be an element of a vector, see
+ // if the implied vector agrees with what we already have and if Offset is
+ // compatible with it.
+ unsigned EltSize = In->getPrimitiveSizeInBits()/8;
+ if (Offset % EltSize == 0 && AllocaSize % EltSize == 0 &&
+ (VectorTy == 0 ||
+ cast<VectorType>(VectorTy)->getElementType()
+ ->getPrimitiveSizeInBits()/8 == EltSize)) {
+ if (VectorTy == 0)
+ VectorTy = VectorType::get(In, AllocaSize/EltSize);
+ return;
+ }
+ }
+
+ // Otherwise, we have a case that we can't handle with an optimized vector
+ // form. We can still turn this into a large integer.
+ VectorTy = Type::getVoidTy(In->getContext());
+}
+
+/// CanConvertToScalar - V is a pointer. If we can convert the pointee and all
+/// its accesses to a single vector type, return true and set VecTy to
+/// the new type. If we could convert the alloca into a single promotable
+/// integer, return true but set VecTy to VoidTy. Further, if the use is not a
+/// completely trivial use that mem2reg could promote, set IsNotTrivial. Offset
+/// is the current offset from the base of the alloca being analyzed.
+///
+/// If we see at least one access to the value that is as a vector type, set the
+/// SawVec flag.
+bool ConvertToScalarInfo::CanConvertToScalar(Value *V, uint64_t Offset) {
+ for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI!=E; ++UI) {
+ Instruction *User = cast<Instruction>(*UI);
+
+ if (LoadInst *LI = dyn_cast<LoadInst>(User)) {
+ // Don't break volatile loads.
+ if (LI->isVolatile())
+ return false;
+ MergeInType(LI->getType(), Offset);
+ continue;
+ }
+
+ if (StoreInst *SI = dyn_cast<StoreInst>(User)) {
+ // Storing the pointer, not into the value?
+ if (SI->getOperand(0) == V || SI->isVolatile()) return false;
+ MergeInType(SI->getOperand(0)->getType(), Offset);
+ continue;
+ }
+
+ if (BitCastInst *BCI = dyn_cast<BitCastInst>(User)) {
+ if (!CanConvertToScalar(BCI, Offset))
+ return false;
+ IsNotTrivial = true;
+ continue;
+ }
+
+ if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(User)) {
+ // If this is a GEP with a variable indices, we can't handle it.
+ if (!GEP->hasAllConstantIndices())
+ return false;
+
+ // Compute the offset that this GEP adds to the pointer.
+ SmallVector<Value*, 8> Indices(GEP->op_begin()+1, GEP->op_end());
+ uint64_t GEPOffset = TD.getIndexedOffset(GEP->getPointerOperandType(),
+ &Indices[0], Indices.size());
+ // See if all uses can be converted.
+ if (!CanConvertToScalar(GEP, Offset+GEPOffset))
+ return false;
+ IsNotTrivial = true;
+ continue;
+ }
+
+ // If this is a constant sized memset of a constant value (e.g. 0) we can
+ // handle it.
+ if (MemSetInst *MSI = dyn_cast<MemSetInst>(User)) {
+ // Store of constant value and constant size.
+ if (isa<ConstantInt>(MSI->getValue()) &&
+ isa<ConstantInt>(MSI->getLength())) {
+ IsNotTrivial = true;
+ continue;
+ }
+ }
+
+ // If this is a memcpy or memmove into or out of the whole allocation, we
+ // can handle it like a load or store of the scalar type.
+ if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(User)) {
+ if (ConstantInt *Len = dyn_cast<ConstantInt>(MTI->getLength()))
+ if (Len->getZExtValue() == AllocaSize && Offset == 0) {
+ IsNotTrivial = true;
+ continue;
+ }
+ }
+
+ // Otherwise, we cannot handle this!
+ return false;
+ }
+
+ return true;
+}
+
+/// ConvertUsesToScalar - Convert all of the users of Ptr to use the new alloca
+/// directly. This happens when we are converting an "integer union" to a
+/// single integer scalar, or when we are converting a "vector union" to a
+/// vector with insert/extractelement instructions.
+///
+/// Offset is an offset from the original alloca, in bits that need to be
+/// shifted to the right. By the end of this, there should be no uses of Ptr.
+void ConvertToScalarInfo::ConvertUsesToScalar(Value *Ptr, AllocaInst *NewAI,
+ uint64_t Offset) {
+ while (!Ptr->use_empty()) {
+ Instruction *User = cast<Instruction>(Ptr->use_back());
+
+ if (BitCastInst *CI = dyn_cast<BitCastInst>(User)) {
+ ConvertUsesToScalar(CI, NewAI, Offset);
+ CI->eraseFromParent();
+ continue;
+ }
+
+ if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(User)) {
+ // Compute the offset that this GEP adds to the pointer.
+ SmallVector<Value*, 8> Indices(GEP->op_begin()+1, GEP->op_end());
+ uint64_t GEPOffset = TD.getIndexedOffset(GEP->getPointerOperandType(),
+ &Indices[0], Indices.size());
+ ConvertUsesToScalar(GEP, NewAI, Offset+GEPOffset*8);
+ GEP->eraseFromParent();
+ continue;
+ }
+
+ IRBuilder<> Builder(User->getParent(), User);
+
+ if (LoadInst *LI = dyn_cast<LoadInst>(User)) {
+ // The load is a bit extract from NewAI shifted right by Offset bits.
+ Value *LoadedVal = Builder.CreateLoad(NewAI, "tmp");
+ Value *NewLoadVal
+ = ConvertScalar_ExtractValue(LoadedVal, LI->getType(), Offset, Builder);
+ LI->replaceAllUsesWith(NewLoadVal);
+ LI->eraseFromParent();
+ continue;
+ }
+
+ if (StoreInst *SI = dyn_cast<StoreInst>(User)) {
+ assert(SI->getOperand(0) != Ptr && "Consistency error!");
+ Instruction *Old = Builder.CreateLoad(NewAI, NewAI->getName()+".in");
+ Value *New = ConvertScalar_InsertValue(SI->getOperand(0), Old, Offset,
+ Builder);
+ Builder.CreateStore(New, NewAI);
+ SI->eraseFromParent();
+
+ // If the load we just inserted is now dead, then the inserted store
+ // overwrote the entire thing.
+ if (Old->use_empty())
+ Old->eraseFromParent();
+ continue;
+ }
+
+ // If this is a constant sized memset of a constant value (e.g. 0) we can
+ // transform it into a store of the expanded constant value.
+ if (MemSetInst *MSI = dyn_cast<MemSetInst>(User)) {
+ assert(MSI->getRawDest() == Ptr && "Consistency error!");
+ unsigned NumBytes = cast<ConstantInt>(MSI->getLength())->getZExtValue();
+ if (NumBytes != 0) {
+ unsigned Val = cast<ConstantInt>(MSI->getValue())->getZExtValue();
+
+ // Compute the value replicated the right number of times.
+ APInt APVal(NumBytes*8, Val);
+
+ // Splat the value if non-zero.
+ if (Val)
+ for (unsigned i = 1; i != NumBytes; ++i)
+ APVal |= APVal << 8;
+
+ Instruction *Old = Builder.CreateLoad(NewAI, NewAI->getName()+".in");
+ Value *New = ConvertScalar_InsertValue(
+ ConstantInt::get(User->getContext(), APVal),
+ Old, Offset, Builder);
+ Builder.CreateStore(New, NewAI);
+
+ // If the load we just inserted is now dead, then the memset overwrote
+ // the entire thing.
+ if (Old->use_empty())
+ Old->eraseFromParent();
+ }
+ MSI->eraseFromParent();
+ continue;
+ }
+
+ // If this is a memcpy or memmove into or out of the whole allocation, we
+ // can handle it like a load or store of the scalar type.
+ if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(User)) {
+ assert(Offset == 0 && "must be store to start of alloca");
+
+ // If the source and destination are both to the same alloca, then this is
+ // a noop copy-to-self, just delete it. Otherwise, emit a load and store
+ // as appropriate.
+ AllocaInst *OrigAI = cast<AllocaInst>(Ptr->getUnderlyingObject(0));
+
+ if (MTI->getSource()->getUnderlyingObject(0) != OrigAI) {
+ // Dest must be OrigAI, change this to be a load from the original
+ // pointer (bitcasted), then a store to our new alloca.
+ assert(MTI->getRawDest() == Ptr && "Neither use is of pointer?");
+ Value *SrcPtr = MTI->getSource();
+ SrcPtr = Builder.CreateBitCast(SrcPtr, NewAI->getType());
+
+ LoadInst *SrcVal = Builder.CreateLoad(SrcPtr, "srcval");
+ SrcVal->setAlignment(MTI->getAlignment());
+ Builder.CreateStore(SrcVal, NewAI);
+ } else if (MTI->getDest()->getUnderlyingObject(0) != OrigAI) {
+ // Src must be OrigAI, change this to be a load from NewAI then a store
+ // through the original dest pointer (bitcasted).
+ assert(MTI->getRawSource() == Ptr && "Neither use is of pointer?");
+ LoadInst *SrcVal = Builder.CreateLoad(NewAI, "srcval");
+
+ Value *DstPtr = Builder.CreateBitCast(MTI->getDest(), NewAI->getType());
+ StoreInst *NewStore = Builder.CreateStore(SrcVal, DstPtr);
+ NewStore->setAlignment(MTI->getAlignment());
+ } else {
+ // Noop transfer. Src == Dst
+ }
+
+ MTI->eraseFromParent();
+ continue;
+ }
+
+ llvm_unreachable("Unsupported operation!");
+ }
+}
+
+/// ConvertScalar_ExtractValue - Extract a value of type ToType from an integer
+/// or vector value FromVal, extracting the bits from the offset specified by
+/// Offset. This returns the value, which is of type ToType.
+///
+/// This happens when we are converting an "integer union" to a single
+/// integer scalar, or when we are converting a "vector union" to a vector with
+/// insert/extractelement instructions.
+///
+/// Offset is an offset from the original alloca, in bits that need to be
+/// shifted to the right.
+Value *ConvertToScalarInfo::
+ConvertScalar_ExtractValue(Value *FromVal, const Type *ToType,
+ uint64_t Offset, IRBuilder<> &Builder) {
+ // If the load is of the whole new alloca, no conversion is needed.
+ if (FromVal->getType() == ToType && Offset == 0)
+ return FromVal;
+
+ // If the result alloca is a vector type, this is either an element
+ // access or a bitcast to another vector type of the same size.
+ if (const VectorType *VTy = dyn_cast<VectorType>(FromVal->getType())) {
+ if (ToType->isVectorTy())
+ return Builder.CreateBitCast(FromVal, ToType, "tmp");
+
+ // Otherwise it must be an element access.
+ unsigned Elt = 0;
+ if (Offset) {
+ unsigned EltSize = TD.getTypeAllocSizeInBits(VTy->getElementType());
+ Elt = Offset/EltSize;
+ assert(EltSize*Elt == Offset && "Invalid modulus in validity checking");
+ }
+ // Return the element extracted out of it.
+ Value *V = Builder.CreateExtractElement(FromVal, ConstantInt::get(
+ Type::getInt32Ty(FromVal->getContext()), Elt), "tmp");
+ if (V->getType() != ToType)
+ V = Builder.CreateBitCast(V, ToType, "tmp");
+ return V;
+ }
+
+ // If ToType is a first class aggregate, extract out each of the pieces and
+ // use insertvalue's to form the FCA.
+ if (const StructType *ST = dyn_cast<StructType>(ToType)) {
+ const StructLayout &Layout = *TD.getStructLayout(ST);
+ Value *Res = UndefValue::get(ST);
+ for (unsigned i = 0, e = ST->getNumElements(); i != e; ++i) {
+ Value *Elt = ConvertScalar_ExtractValue(FromVal, ST->getElementType(i),
+ Offset+Layout.getElementOffsetInBits(i),
+ Builder);
+ Res = Builder.CreateInsertValue(Res, Elt, i, "tmp");
+ }
+ return Res;
+ }
+
+ if (const ArrayType *AT = dyn_cast<ArrayType>(ToType)) {
+ uint64_t EltSize = TD.getTypeAllocSizeInBits(AT->getElementType());
+ Value *Res = UndefValue::get(AT);
+ for (unsigned i = 0, e = AT->getNumElements(); i != e; ++i) {
+ Value *Elt = ConvertScalar_ExtractValue(FromVal, AT->getElementType(),
+ Offset+i*EltSize, Builder);
+ Res = Builder.CreateInsertValue(Res, Elt, i, "tmp");
+ }
+ return Res;
+ }
+
+ // Otherwise, this must be a union that was converted to an integer value.
+ const IntegerType *NTy = cast<IntegerType>(FromVal->getType());
+
+ // If this is a big-endian system and the load is narrower than the
+ // full alloca type, we need to do a shift to get the right bits.
+ int ShAmt = 0;
+ if (TD.isBigEndian()) {
+ // On big-endian machines, the lowest bit is stored at the bit offset
+ // from the pointer given by getTypeStoreSizeInBits. This matters for
+ // integers with a bitwidth that is not a multiple of 8.
+ ShAmt = TD.getTypeStoreSizeInBits(NTy) -
+ TD.getTypeStoreSizeInBits(ToType) - Offset;
+ } else {
+ ShAmt = Offset;
+ }
+
+ // Note: we support negative bitwidths (with shl) which are not defined.
+ // We do this to support (f.e.) loads off the end of a structure where
+ // only some bits are used.
+ if (ShAmt > 0 && (unsigned)ShAmt < NTy->getBitWidth())
+ FromVal = Builder.CreateLShr(FromVal,
+ ConstantInt::get(FromVal->getType(),
+ ShAmt), "tmp");
+ else if (ShAmt < 0 && (unsigned)-ShAmt < NTy->getBitWidth())
+ FromVal = Builder.CreateShl(FromVal,
+ ConstantInt::get(FromVal->getType(),
+ -ShAmt), "tmp");
+
+ // Finally, unconditionally truncate the integer to the right width.
+ unsigned LIBitWidth = TD.getTypeSizeInBits(ToType);
+ if (LIBitWidth < NTy->getBitWidth())
+ FromVal =
+ Builder.CreateTrunc(FromVal, IntegerType::get(FromVal->getContext(),
+ LIBitWidth), "tmp");
+ else if (LIBitWidth > NTy->getBitWidth())
+ FromVal =
+ Builder.CreateZExt(FromVal, IntegerType::get(FromVal->getContext(),
+ LIBitWidth), "tmp");
+
+ // If the result is an integer, this is a trunc or bitcast.
+ if (ToType->isIntegerTy()) {
+ // Should be done.
+ } else if (ToType->isFloatingPointTy() || ToType->isVectorTy()) {
+ // Just do a bitcast, we know the sizes match up.
+ FromVal = Builder.CreateBitCast(FromVal, ToType, "tmp");
+ } else {
+ // Otherwise must be a pointer.
+ FromVal = Builder.CreateIntToPtr(FromVal, ToType, "tmp");
+ }
+ assert(FromVal->getType() == ToType && "Didn't convert right?");
+ return FromVal;
+}
+
+/// ConvertScalar_InsertValue - Insert the value "SV" into the existing integer
+/// or vector value "Old" at the offset specified by Offset.
+///
+/// This happens when we are converting an "integer union" to a
+/// single integer scalar, or when we are converting a "vector union" to a
+/// vector with insert/extractelement instructions.
+///
+/// Offset is an offset from the original alloca, in bits that need to be
+/// shifted to the right.
+Value *ConvertToScalarInfo::
+ConvertScalar_InsertValue(Value *SV, Value *Old,
+ uint64_t Offset, IRBuilder<> &Builder) {
+ // Convert the stored type to the actual type, shift it left to insert
+ // then 'or' into place.
+ const Type *AllocaType = Old->getType();
+ LLVMContext &Context = Old->getContext();
+
+ if (const VectorType *VTy = dyn_cast<VectorType>(AllocaType)) {
+ uint64_t VecSize = TD.getTypeAllocSizeInBits(VTy);
+ uint64_t ValSize = TD.getTypeAllocSizeInBits(SV->getType());
+
+ // Changing the whole vector with memset or with an access of a different
+ // vector type?
+ if (ValSize == VecSize)
+ return Builder.CreateBitCast(SV, AllocaType, "tmp");
+
+ uint64_t EltSize = TD.getTypeAllocSizeInBits(VTy->getElementType());
+
+ // Must be an element insertion.
+ unsigned Elt = Offset/EltSize;
+
+ if (SV->getType() != VTy->getElementType())
+ SV = Builder.CreateBitCast(SV, VTy->getElementType(), "tmp");
+
+ SV = Builder.CreateInsertElement(Old, SV,
+ ConstantInt::get(Type::getInt32Ty(SV->getContext()), Elt),
+ "tmp");
+ return SV;
+ }
+
+ // If SV is a first-class aggregate value, insert each value recursively.
+ if (const StructType *ST = dyn_cast<StructType>(SV->getType())) {
+ const StructLayout &Layout = *TD.getStructLayout(ST);
+ for (unsigned i = 0, e = ST->getNumElements(); i != e; ++i) {
+ Value *Elt = Builder.CreateExtractValue(SV, i, "tmp");
+ Old = ConvertScalar_InsertValue(Elt, Old,
+ Offset+Layout.getElementOffsetInBits(i),
+ Builder);
+ }
+ return Old;
+ }
+
+ if (const ArrayType *AT = dyn_cast<ArrayType>(SV->getType())) {
+ uint64_t EltSize = TD.getTypeAllocSizeInBits(AT->getElementType());
+ for (unsigned i = 0, e = AT->getNumElements(); i != e; ++i) {
+ Value *Elt = Builder.CreateExtractValue(SV, i, "tmp");
+ Old = ConvertScalar_InsertValue(Elt, Old, Offset+i*EltSize, Builder);
+ }
+ return Old;
+ }
+
+ // If SV is a float, convert it to the appropriate integer type.
+ // If it is a pointer, do the same.
+ unsigned SrcWidth = TD.getTypeSizeInBits(SV->getType());
+ unsigned DestWidth = TD.getTypeSizeInBits(AllocaType);
+ unsigned SrcStoreWidth = TD.getTypeStoreSizeInBits(SV->getType());
+ unsigned DestStoreWidth = TD.getTypeStoreSizeInBits(AllocaType);
+ if (SV->getType()->isFloatingPointTy() || SV->getType()->isVectorTy())
+ SV = Builder.CreateBitCast(SV,
+ IntegerType::get(SV->getContext(),SrcWidth), "tmp");
+ else if (SV->getType()->isPointerTy())
+ SV = Builder.CreatePtrToInt(SV, TD.getIntPtrType(SV->getContext()), "tmp");
+
+ // Zero extend or truncate the value if needed.
+ if (SV->getType() != AllocaType) {
+ if (SV->getType()->getPrimitiveSizeInBits() <
+ AllocaType->getPrimitiveSizeInBits())
+ SV = Builder.CreateZExt(SV, AllocaType, "tmp");
+ else {
+ // Truncation may be needed if storing more than the alloca can hold
+ // (undefined behavior).
+ SV = Builder.CreateTrunc(SV, AllocaType, "tmp");
+ SrcWidth = DestWidth;
+ SrcStoreWidth = DestStoreWidth;
+ }
+ }
+
+ // If this is a big-endian system and the store is narrower than the
+ // full alloca type, we need to do a shift to get the right bits.
+ int ShAmt = 0;
+ if (TD.isBigEndian()) {
+ // On big-endian machines, the lowest bit is stored at the bit offset
+ // from the pointer given by getTypeStoreSizeInBits. This matters for
+ // integers with a bitwidth that is not a multiple of 8.
+ ShAmt = DestStoreWidth - SrcStoreWidth - Offset;
+ } else {
+ ShAmt = Offset;
+ }
+
+ // Note: we support negative bitwidths (with shr) which are not defined.
+ // We do this to support (f.e.) stores off the end of a structure where
+ // only some bits in the structure are set.
+ APInt Mask(APInt::getLowBitsSet(DestWidth, SrcWidth));
+ if (ShAmt > 0 && (unsigned)ShAmt < DestWidth) {
+ SV = Builder.CreateShl(SV, ConstantInt::get(SV->getType(),
+ ShAmt), "tmp");
+ Mask <<= ShAmt;
+ } else if (ShAmt < 0 && (unsigned)-ShAmt < DestWidth) {
+ SV = Builder.CreateLShr(SV, ConstantInt::get(SV->getType(),
+ -ShAmt), "tmp");
+ Mask = Mask.lshr(-ShAmt);
+ }
+
+ // Mask out the bits we are about to insert from the old value, and or
+ // in the new bits.
+ if (SrcWidth != DestWidth) {
+ assert(DestWidth > SrcWidth);
+ Old = Builder.CreateAnd(Old, ConstantInt::get(Context, ~Mask), "mask");
+ SV = Builder.CreateOr(Old, SV, "ins");
+ }
+ return SV;
+}
+
+
+//===----------------------------------------------------------------------===//
+// SRoA Driver
+//===----------------------------------------------------------------------===//
+
+
bool SROA::runOnFunction(Function &F) {
TD = getAnalysisIfAvailable<TargetData>();
@@ -197,6 +762,7 @@
return Changed;
}
+
/// ShouldAttemptScalarRepl - Decide if an alloca is a good candidate for
/// SROA. It must be a struct or array type with a small number of elements.
static bool ShouldAttemptScalarRepl(AllocaInst *AI) {
@@ -211,68 +777,6 @@
return false;
}
-namespace {
-/// ConvertToScalarInfo - This struct is used by CanConvertToScalar
-struct ConvertToScalarInfo {
- /// AllocaSize - The size of the alloca being considered.
- unsigned AllocaSize;
- const TargetData &TD;
-
- bool IsNotTrivial;
- const Type *VectorTy;
- bool HadAVector;
-
- explicit ConvertToScalarInfo(unsigned Size, const TargetData &td)
- : AllocaSize(Size), TD(td) {
- IsNotTrivial = false;
- VectorTy = 0;
- HadAVector = false;
- }
-
- bool shouldConvertToVector() const {
- return VectorTy && VectorTy->isVectorTy() && HadAVector;
- }
-
- AllocaInst *TryConvert(AllocaInst *AI) {
- // If we can't convert this scalar, or if mem2reg can trivially do it, bail
- // out.
- if (!CanConvertToScalar(AI, 0) || !IsNotTrivial)
- // FIXME: In the trivial case, just use mem2reg.
- return 0;
-
- // If we were able to find a vector type that can handle this with
- // insert/extract elements, and if there was at least one use that had
- // a vector type, promote this to a vector. We don't want to promote
- // random stuff that doesn't use vectors (e.g. <9 x double>) because then
- // we just get a lot of insert/extracts. If at least one vector is
- // involved, then we probably really do have a union of vector/array.
- const Type *NewTy;
- if (shouldConvertToVector()) {
- DEBUG(dbgs() << "CONVERT TO VECTOR: " << *AI << "\n TYPE = "
- << *VectorTy << '\n');
- NewTy = VectorTy; // Use the vector type.
- } else {
- DEBUG(dbgs() << "CONVERT TO SCALAR INTEGER: " << *AI << "\n");
- // Create and insert the integer alloca.
- NewTy = IntegerType::get(AI->getContext(), AllocaSize*8);
- }
- AllocaInst *NewAI = new AllocaInst(NewTy, 0, "", AI->getParent()->begin());
- ConvertUsesToScalar(AI, NewAI, 0);
- return NewAI;
- }
-
- bool CanConvertToScalar(Value *V, uint64_t Offset);
- void MergeInType(const Type *In, uint64_t Offset);
- void ConvertUsesToScalar(Value *Ptr, AllocaInst *NewAI, uint64_t Offset);
-
- Value *ConvertScalar_ExtractValue(Value *NV, const Type *ToType,
- uint64_t Offset, IRBuilder<> &Builder);
- Value *ConvertScalar_InsertValue(Value *StoredVal, Value *ExistingVal,
- uint64_t Offset, IRBuilder<> &Builder);
-};
-} // end anonymous namespace.
-
-
// performScalarRepl - This algorithm is a simple worklist driven algorithm,
// which runs on all of the malloc/alloca instructions in the function, removing
@@ -1208,504 +1712,6 @@
return true;
}
-/// MergeInType - Add the 'In' type to the accumulated type (Accum) so far at
-/// the offset specified by Offset (which is specified in bytes).
-///
-/// There are two cases we handle here:
-/// 1) A union of vector types of the same size and potentially its elements.
-/// Here we turn element accesses into insert/extract element operations.
-/// This promotes a <4 x float> with a store of float to the third element
-/// into a <4 x float> that uses insert element.
-/// 2) A fully general blob of memory, which we turn into some (potentially
-/// large) integer type with extract and insert operations where the loads
-/// and stores would mutate the memory.
-void ConvertToScalarInfo::MergeInType(const Type *In, uint64_t Offset) {
- // Remember if we saw a vector type.
- HadAVector |= In->isVectorTy();
-
- if (VectorTy && VectorTy->isVoidTy())
- return;
-
- // If this could be contributing to a vector, analyze it.
-
- // If the In type is a vector that is the same size as the alloca, see if it
- // matches the existing VecTy.
- if (const VectorType *VInTy = dyn_cast<VectorType>(In)) {
- if (VInTy->getBitWidth()/8 == AllocaSize && Offset == 0) {
- // If we're storing/loading a vector of the right size, allow it as a
- // vector. If this the first vector we see, remember the type so that
- // we know the element size.
- if (VectorTy == 0)
- VectorTy = VInTy;
- return;
- }
- } else if (In->isFloatTy() || In->isDoubleTy() ||
- (In->isIntegerTy() && In->getPrimitiveSizeInBits() >= 8 &&
- isPowerOf2_32(In->getPrimitiveSizeInBits()))) {
- // If we're accessing something that could be an element of a vector, see
- // if the implied vector agrees with what we already have and if Offset is
- // compatible with it.
- unsigned EltSize = In->getPrimitiveSizeInBits()/8;
- if (Offset % EltSize == 0 && AllocaSize % EltSize == 0 &&
- (VectorTy == 0 ||
- cast<VectorType>(VectorTy)->getElementType()
- ->getPrimitiveSizeInBits()/8 == EltSize)) {
- if (VectorTy == 0)
- VectorTy = VectorType::get(In, AllocaSize/EltSize);
- return;
- }
- }
-
- // Otherwise, we have a case that we can't handle with an optimized vector
- // form. We can still turn this into a large integer.
- VectorTy = Type::getVoidTy(In->getContext());
-}
-
-/// CanConvertToScalar - V is a pointer. If we can convert the pointee and all
-/// its accesses to a single vector type, return true and set VecTy to
-/// the new type. If we could convert the alloca into a single promotable
-/// integer, return true but set VecTy to VoidTy. Further, if the use is not a
-/// completely trivial use that mem2reg could promote, set IsNotTrivial. Offset
-/// is the current offset from the base of the alloca being analyzed.
-///
-/// If we see at least one access to the value that is as a vector type, set the
-/// SawVec flag.
-bool ConvertToScalarInfo::CanConvertToScalar(Value *V, uint64_t Offset) {
- for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI!=E; ++UI) {
- Instruction *User = cast<Instruction>(*UI);
-
- if (LoadInst *LI = dyn_cast<LoadInst>(User)) {
- // Don't break volatile loads.
- if (LI->isVolatile())
- return false;
- MergeInType(LI->getType(), Offset);
- continue;
- }
-
- if (StoreInst *SI = dyn_cast<StoreInst>(User)) {
- // Storing the pointer, not into the value?
- if (SI->getOperand(0) == V || SI->isVolatile()) return false;
- MergeInType(SI->getOperand(0)->getType(), Offset);
- continue;
- }
-
- if (BitCastInst *BCI = dyn_cast<BitCastInst>(User)) {
- if (!CanConvertToScalar(BCI, Offset))
- return false;
- IsNotTrivial = true;
- continue;
- }
-
- if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(User)) {
- // If this is a GEP with a variable indices, we can't handle it.
- if (!GEP->hasAllConstantIndices())
- return false;
-
- // Compute the offset that this GEP adds to the pointer.
- SmallVector<Value*, 8> Indices(GEP->op_begin()+1, GEP->op_end());
- uint64_t GEPOffset = TD.getIndexedOffset(GEP->getPointerOperandType(),
- &Indices[0], Indices.size());
- // See if all uses can be converted.
- if (!CanConvertToScalar(GEP, Offset+GEPOffset))
- return false;
- IsNotTrivial = true;
- continue;
- }
-
- // If this is a constant sized memset of a constant value (e.g. 0) we can
- // handle it.
- if (MemSetInst *MSI = dyn_cast<MemSetInst>(User)) {
- // Store of constant value and constant size.
- if (isa<ConstantInt>(MSI->getValue()) &&
- isa<ConstantInt>(MSI->getLength())) {
- IsNotTrivial = true;
- continue;
- }
- }
-
- // If this is a memcpy or memmove into or out of the whole allocation, we
- // can handle it like a load or store of the scalar type.
- if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(User)) {
- if (ConstantInt *Len = dyn_cast<ConstantInt>(MTI->getLength()))
- if (Len->getZExtValue() == AllocaSize && Offset == 0) {
- IsNotTrivial = true;
- continue;
- }
- }
-
- // Otherwise, we cannot handle this!
- return false;
- }
-
- return true;
-}
-
-/// ConvertUsesToScalar - Convert all of the users of Ptr to use the new alloca
-/// directly. This happens when we are converting an "integer union" to a
-/// single integer scalar, or when we are converting a "vector union" to a
-/// vector with insert/extractelement instructions.
-///
-/// Offset is an offset from the original alloca, in bits that need to be
-/// shifted to the right. By the end of this, there should be no uses of Ptr.
-void ConvertToScalarInfo::ConvertUsesToScalar(Value *Ptr, AllocaInst *NewAI,
- uint64_t Offset) {
- while (!Ptr->use_empty()) {
- Instruction *User = cast<Instruction>(Ptr->use_back());
-
- if (BitCastInst *CI = dyn_cast<BitCastInst>(User)) {
- ConvertUsesToScalar(CI, NewAI, Offset);
- CI->eraseFromParent();
- continue;
- }
-
- if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(User)) {
- // Compute the offset that this GEP adds to the pointer.
- SmallVector<Value*, 8> Indices(GEP->op_begin()+1, GEP->op_end());
- uint64_t GEPOffset = TD.getIndexedOffset(GEP->getPointerOperandType(),
- &Indices[0], Indices.size());
- ConvertUsesToScalar(GEP, NewAI, Offset+GEPOffset*8);
- GEP->eraseFromParent();
- continue;
- }
-
- IRBuilder<> Builder(User->getParent(), User);
-
- if (LoadInst *LI = dyn_cast<LoadInst>(User)) {
- // The load is a bit extract from NewAI shifted right by Offset bits.
- Value *LoadedVal = Builder.CreateLoad(NewAI, "tmp");
- Value *NewLoadVal
- = ConvertScalar_ExtractValue(LoadedVal, LI->getType(), Offset, Builder);
- LI->replaceAllUsesWith(NewLoadVal);
- LI->eraseFromParent();
- continue;
- }
-
- if (StoreInst *SI = dyn_cast<StoreInst>(User)) {
- assert(SI->getOperand(0) != Ptr && "Consistency error!");
- Instruction *Old = Builder.CreateLoad(NewAI, NewAI->getName()+".in");
- Value *New = ConvertScalar_InsertValue(SI->getOperand(0), Old, Offset,
- Builder);
- Builder.CreateStore(New, NewAI);
- SI->eraseFromParent();
-
- // If the load we just inserted is now dead, then the inserted store
- // overwrote the entire thing.
- if (Old->use_empty())
- Old->eraseFromParent();
- continue;
- }
-
- // If this is a constant sized memset of a constant value (e.g. 0) we can
- // transform it into a store of the expanded constant value.
- if (MemSetInst *MSI = dyn_cast<MemSetInst>(User)) {
- assert(MSI->getRawDest() == Ptr && "Consistency error!");
- unsigned NumBytes = cast<ConstantInt>(MSI->getLength())->getZExtValue();
- if (NumBytes != 0) {
- unsigned Val = cast<ConstantInt>(MSI->getValue())->getZExtValue();
-
- // Compute the value replicated the right number of times.
- APInt APVal(NumBytes*8, Val);
-
- // Splat the value if non-zero.
- if (Val)
- for (unsigned i = 1; i != NumBytes; ++i)
- APVal |= APVal << 8;
-
- Instruction *Old = Builder.CreateLoad(NewAI, NewAI->getName()+".in");
- Value *New = ConvertScalar_InsertValue(
- ConstantInt::get(User->getContext(), APVal),
- Old, Offset, Builder);
- Builder.CreateStore(New, NewAI);
-
- // If the load we just inserted is now dead, then the memset overwrote
- // the entire thing.
- if (Old->use_empty())
- Old->eraseFromParent();
- }
- MSI->eraseFromParent();
- continue;
- }
-
- // If this is a memcpy or memmove into or out of the whole allocation, we
- // can handle it like a load or store of the scalar type.
- if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(User)) {
- assert(Offset == 0 && "must be store to start of alloca");
-
- // If the source and destination are both to the same alloca, then this is
- // a noop copy-to-self, just delete it. Otherwise, emit a load and store
- // as appropriate.
- AllocaInst *OrigAI = cast<AllocaInst>(Ptr->getUnderlyingObject(0));
-
- if (MTI->getSource()->getUnderlyingObject(0) != OrigAI) {
- // Dest must be OrigAI, change this to be a load from the original
- // pointer (bitcasted), then a store to our new alloca.
- assert(MTI->getRawDest() == Ptr && "Neither use is of pointer?");
- Value *SrcPtr = MTI->getSource();
- SrcPtr = Builder.CreateBitCast(SrcPtr, NewAI->getType());
-
- LoadInst *SrcVal = Builder.CreateLoad(SrcPtr, "srcval");
- SrcVal->setAlignment(MTI->getAlignment());
- Builder.CreateStore(SrcVal, NewAI);
- } else if (MTI->getDest()->getUnderlyingObject(0) != OrigAI) {
- // Src must be OrigAI, change this to be a load from NewAI then a store
- // through the original dest pointer (bitcasted).
- assert(MTI->getRawSource() == Ptr && "Neither use is of pointer?");
- LoadInst *SrcVal = Builder.CreateLoad(NewAI, "srcval");
-
- Value *DstPtr = Builder.CreateBitCast(MTI->getDest(), NewAI->getType());
- StoreInst *NewStore = Builder.CreateStore(SrcVal, DstPtr);
- NewStore->setAlignment(MTI->getAlignment());
- } else {
- // Noop transfer. Src == Dst
- }
-
- MTI->eraseFromParent();
- continue;
- }
-
- llvm_unreachable("Unsupported operation!");
- }
-}
-
-/// ConvertScalar_ExtractValue - Extract a value of type ToType from an integer
-/// or vector value FromVal, extracting the bits from the offset specified by
-/// Offset. This returns the value, which is of type ToType.
-///
-/// This happens when we are converting an "integer union" to a single
-/// integer scalar, or when we are converting a "vector union" to a vector with
-/// insert/extractelement instructions.
-///
-/// Offset is an offset from the original alloca, in bits that need to be
-/// shifted to the right.
-Value *ConvertToScalarInfo::
-ConvertScalar_ExtractValue(Value *FromVal, const Type *ToType,
- uint64_t Offset, IRBuilder<> &Builder) {
- // If the load is of the whole new alloca, no conversion is needed.
- if (FromVal->getType() == ToType && Offset == 0)
- return FromVal;
-
- // If the result alloca is a vector type, this is either an element
- // access or a bitcast to another vector type of the same size.
- if (const VectorType *VTy = dyn_cast<VectorType>(FromVal->getType())) {
- if (ToType->isVectorTy())
- return Builder.CreateBitCast(FromVal, ToType, "tmp");
-
- // Otherwise it must be an element access.
- unsigned Elt = 0;
- if (Offset) {
- unsigned EltSize = TD.getTypeAllocSizeInBits(VTy->getElementType());
- Elt = Offset/EltSize;
- assert(EltSize*Elt == Offset && "Invalid modulus in validity checking");
- }
- // Return the element extracted out of it.
- Value *V = Builder.CreateExtractElement(FromVal, ConstantInt::get(
- Type::getInt32Ty(FromVal->getContext()), Elt), "tmp");
- if (V->getType() != ToType)
- V = Builder.CreateBitCast(V, ToType, "tmp");
- return V;
- }
-
- // If ToType is a first class aggregate, extract out each of the pieces and
- // use insertvalue's to form the FCA.
- if (const StructType *ST = dyn_cast<StructType>(ToType)) {
- const StructLayout &Layout = *TD.getStructLayout(ST);
- Value *Res = UndefValue::get(ST);
- for (unsigned i = 0, e = ST->getNumElements(); i != e; ++i) {
- Value *Elt = ConvertScalar_ExtractValue(FromVal, ST->getElementType(i),
- Offset+Layout.getElementOffsetInBits(i),
- Builder);
- Res = Builder.CreateInsertValue(Res, Elt, i, "tmp");
- }
- return Res;
- }
-
- if (const ArrayType *AT = dyn_cast<ArrayType>(ToType)) {
- uint64_t EltSize = TD.getTypeAllocSizeInBits(AT->getElementType());
- Value *Res = UndefValue::get(AT);
- for (unsigned i = 0, e = AT->getNumElements(); i != e; ++i) {
- Value *Elt = ConvertScalar_ExtractValue(FromVal, AT->getElementType(),
- Offset+i*EltSize, Builder);
- Res = Builder.CreateInsertValue(Res, Elt, i, "tmp");
- }
- return Res;
- }
-
- // Otherwise, this must be a union that was converted to an integer value.
- const IntegerType *NTy = cast<IntegerType>(FromVal->getType());
-
- // If this is a big-endian system and the load is narrower than the
- // full alloca type, we need to do a shift to get the right bits.
- int ShAmt = 0;
- if (TD.isBigEndian()) {
- // On big-endian machines, the lowest bit is stored at the bit offset
- // from the pointer given by getTypeStoreSizeInBits. This matters for
- // integers with a bitwidth that is not a multiple of 8.
- ShAmt = TD.getTypeStoreSizeInBits(NTy) -
- TD.getTypeStoreSizeInBits(ToType) - Offset;
- } else {
- ShAmt = Offset;
- }
-
- // Note: we support negative bitwidths (with shl) which are not defined.
- // We do this to support (f.e.) loads off the end of a structure where
- // only some bits are used.
- if (ShAmt > 0 && (unsigned)ShAmt < NTy->getBitWidth())
- FromVal = Builder.CreateLShr(FromVal,
- ConstantInt::get(FromVal->getType(),
- ShAmt), "tmp");
- else if (ShAmt < 0 && (unsigned)-ShAmt < NTy->getBitWidth())
- FromVal = Builder.CreateShl(FromVal,
- ConstantInt::get(FromVal->getType(),
- -ShAmt), "tmp");
-
- // Finally, unconditionally truncate the integer to the right width.
- unsigned LIBitWidth = TD.getTypeSizeInBits(ToType);
- if (LIBitWidth < NTy->getBitWidth())
- FromVal =
- Builder.CreateTrunc(FromVal, IntegerType::get(FromVal->getContext(),
- LIBitWidth), "tmp");
- else if (LIBitWidth > NTy->getBitWidth())
- FromVal =
- Builder.CreateZExt(FromVal, IntegerType::get(FromVal->getContext(),
- LIBitWidth), "tmp");
-
- // If the result is an integer, this is a trunc or bitcast.
- if (ToType->isIntegerTy()) {
- // Should be done.
- } else if (ToType->isFloatingPointTy() || ToType->isVectorTy()) {
- // Just do a bitcast, we know the sizes match up.
- FromVal = Builder.CreateBitCast(FromVal, ToType, "tmp");
- } else {
- // Otherwise must be a pointer.
- FromVal = Builder.CreateIntToPtr(FromVal, ToType, "tmp");
- }
- assert(FromVal->getType() == ToType && "Didn't convert right?");
- return FromVal;
-}
-
-/// ConvertScalar_InsertValue - Insert the value "SV" into the existing integer
-/// or vector value "Old" at the offset specified by Offset.
-///
-/// This happens when we are converting an "integer union" to a
-/// single integer scalar, or when we are converting a "vector union" to a
-/// vector with insert/extractelement instructions.
-///
-/// Offset is an offset from the original alloca, in bits that need to be
-/// shifted to the right.
-Value *ConvertToScalarInfo::
-ConvertScalar_InsertValue(Value *SV, Value *Old,
- uint64_t Offset, IRBuilder<> &Builder) {
- // Convert the stored type to the actual type, shift it left to insert
- // then 'or' into place.
- const Type *AllocaType = Old->getType();
- LLVMContext &Context = Old->getContext();
-
- if (const VectorType *VTy = dyn_cast<VectorType>(AllocaType)) {
- uint64_t VecSize = TD.getTypeAllocSizeInBits(VTy);
- uint64_t ValSize = TD.getTypeAllocSizeInBits(SV->getType());
-
- // Changing the whole vector with memset or with an access of a different
- // vector type?
- if (ValSize == VecSize)
- return Builder.CreateBitCast(SV, AllocaType, "tmp");
-
- uint64_t EltSize = TD.getTypeAllocSizeInBits(VTy->getElementType());
-
- // Must be an element insertion.
- unsigned Elt = Offset/EltSize;
-
- if (SV->getType() != VTy->getElementType())
- SV = Builder.CreateBitCast(SV, VTy->getElementType(), "tmp");
-
- SV = Builder.CreateInsertElement(Old, SV,
- ConstantInt::get(Type::getInt32Ty(SV->getContext()), Elt),
- "tmp");
- return SV;
- }
-
- // If SV is a first-class aggregate value, insert each value recursively.
- if (const StructType *ST = dyn_cast<StructType>(SV->getType())) {
- const StructLayout &Layout = *TD.getStructLayout(ST);
- for (unsigned i = 0, e = ST->getNumElements(); i != e; ++i) {
- Value *Elt = Builder.CreateExtractValue(SV, i, "tmp");
- Old = ConvertScalar_InsertValue(Elt, Old,
- Offset+Layout.getElementOffsetInBits(i),
- Builder);
- }
- return Old;
- }
-
- if (const ArrayType *AT = dyn_cast<ArrayType>(SV->getType())) {
- uint64_t EltSize = TD.getTypeAllocSizeInBits(AT->getElementType());
- for (unsigned i = 0, e = AT->getNumElements(); i != e; ++i) {
- Value *Elt = Builder.CreateExtractValue(SV, i, "tmp");
- Old = ConvertScalar_InsertValue(Elt, Old, Offset+i*EltSize, Builder);
- }
- return Old;
- }
-
- // If SV is a float, convert it to the appropriate integer type.
- // If it is a pointer, do the same.
- unsigned SrcWidth = TD.getTypeSizeInBits(SV->getType());
- unsigned DestWidth = TD.getTypeSizeInBits(AllocaType);
- unsigned SrcStoreWidth = TD.getTypeStoreSizeInBits(SV->getType());
- unsigned DestStoreWidth = TD.getTypeStoreSizeInBits(AllocaType);
- if (SV->getType()->isFloatingPointTy() || SV->getType()->isVectorTy())
- SV = Builder.CreateBitCast(SV,
- IntegerType::get(SV->getContext(),SrcWidth), "tmp");
- else if (SV->getType()->isPointerTy())
- SV = Builder.CreatePtrToInt(SV, TD.getIntPtrType(SV->getContext()), "tmp");
-
- // Zero extend or truncate the value if needed.
- if (SV->getType() != AllocaType) {
- if (SV->getType()->getPrimitiveSizeInBits() <
- AllocaType->getPrimitiveSizeInBits())
- SV = Builder.CreateZExt(SV, AllocaType, "tmp");
- else {
- // Truncation may be needed if storing more than the alloca can hold
- // (undefined behavior).
- SV = Builder.CreateTrunc(SV, AllocaType, "tmp");
- SrcWidth = DestWidth;
- SrcStoreWidth = DestStoreWidth;
- }
- }
-
- // If this is a big-endian system and the store is narrower than the
- // full alloca type, we need to do a shift to get the right bits.
- int ShAmt = 0;
- if (TD.isBigEndian()) {
- // On big-endian machines, the lowest bit is stored at the bit offset
- // from the pointer given by getTypeStoreSizeInBits. This matters for
- // integers with a bitwidth that is not a multiple of 8.
- ShAmt = DestStoreWidth - SrcStoreWidth - Offset;
- } else {
- ShAmt = Offset;
- }
-
- // Note: we support negative bitwidths (with shr) which are not defined.
- // We do this to support (f.e.) stores off the end of a structure where
- // only some bits in the structure are set.
- APInt Mask(APInt::getLowBitsSet(DestWidth, SrcWidth));
- if (ShAmt > 0 && (unsigned)ShAmt < DestWidth) {
- SV = Builder.CreateShl(SV, ConstantInt::get(SV->getType(),
- ShAmt), "tmp");
- Mask <<= ShAmt;
- } else if (ShAmt < 0 && (unsigned)-ShAmt < DestWidth) {
- SV = Builder.CreateLShr(SV, ConstantInt::get(SV->getType(),
- -ShAmt), "tmp");
- Mask = Mask.lshr(-ShAmt);
- }
-
- // Mask out the bits we are about to insert from the old value, and or
- // in the new bits.
- if (SrcWidth != DestWidth) {
- assert(DestWidth > SrcWidth);
- Old = Builder.CreateAnd(Old, ConstantInt::get(Context, ~Mask), "mask");
- SV = Builder.CreateOr(Old, SV, "ins");
- }
- return SV;
-}
-
/// PointsToConstantGlobal - Return true if V (possibly indirectly) points to