#include "llvm/Instructions.h"
#include "llvm/IntrinsicInst.h"
#include "llvm/LLVMContext.h"
+#include "llvm/Module.h"
#include "llvm/Pass.h"
#include "llvm/Analysis/Dominators.h"
+#include "llvm/Analysis/Loads.h"
+#include "llvm/Analysis/ValueTracking.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Transforms/Utils/PromoteMemToReg.h"
#include "llvm/Transforms/Utils/Local.h"
+#include "llvm/Transforms/Utils/SSAUpdater.h"
+#include "llvm/Support/CallSite.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/GetElementPtrTypeIterator.h"
#include "llvm/Support/IRBuilder.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/raw_ostream.h"
+#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
using namespace llvm;
STATISTIC(NumReplaced, "Number of allocas broken up");
STATISTIC(NumPromoted, "Number of allocas promoted");
+STATISTIC(NumAdjusted, "Number of scalar allocas adjusted to allow promotion");
STATISTIC(NumConverted, "Number of aggregates converted to scalar");
STATISTIC(NumGlobals, "Number of allocas copied from constant global");
namespace {
struct SROA : public FunctionPass {
- static char ID; // Pass identification, replacement for typeid
- explicit SROA(signed T = -1) : FunctionPass(&ID) {
+ SROA(int T, bool hasDT, char &ID)
+ : FunctionPass(ID), HasDomTree(hasDT) {
if (T == -1)
SRThreshold = 128;
else
bool performScalarRepl(Function &F);
bool performPromotion(Function &F);
- // getAnalysisUsage - This pass does not require any passes, but we know it
- // will not alter the CFG, so say so.
- virtual void getAnalysisUsage(AnalysisUsage &AU) const {
- AU.addRequired<DominatorTree>();
- AU.addRequired<DominanceFrontier>();
- AU.setPreservesCFG();
- }
-
private:
+ bool HasDomTree;
TargetData *TD;
-
+
/// DeadInsts - Keep track of instructions we have made dead, so that
/// we can remove them after we are done working.
SmallVector<Value*, 32> DeadInsts;
/// information about the uses. All these fields are initialized to false
/// and set to true when something is learned.
struct AllocaInfo {
+ /// The alloca to promote.
+ AllocaInst *AI;
+
+ /// CheckedPHIs - This is a set of verified PHI nodes, to prevent infinite
+ /// looping and avoid redundant work.
+ SmallPtrSet<PHINode*, 8> CheckedPHIs;
+
/// isUnsafe - This is set to true if the alloca cannot be SROA'd.
bool isUnsafe : 1;
-
+
/// isMemCpySrc - This is true if this aggregate is memcpy'd from.
bool isMemCpySrc : 1;
/// isMemCpyDst - This is true if this aggregate is memcpy'd into.
bool isMemCpyDst : 1;
- AllocaInfo()
- : isUnsafe(false), isMemCpySrc(false), isMemCpyDst(false) {}
+ /// hasSubelementAccess - This is true if a subelement of the alloca is
+ /// ever accessed, or false if the alloca is only accessed with mem
+ /// intrinsics or load/store that only access the entire alloca at once.
+ bool hasSubelementAccess : 1;
+
+ /// hasALoadOrStore - This is true if there are any loads or stores to it.
+ /// The alloca may just be accessed with memcpy, for example, which would
+ /// not set this.
+ bool hasALoadOrStore : 1;
+
+ explicit AllocaInfo(AllocaInst *ai)
+ : AI(ai), isUnsafe(false), isMemCpySrc(false), isMemCpyDst(false),
+ hasSubelementAccess(false), hasALoadOrStore(false) {}
};
-
+
unsigned SRThreshold;
- void MarkUnsafe(AllocaInfo &I) { I.isUnsafe = true; }
+ void MarkUnsafe(AllocaInfo &I, Instruction *User) {
+ I.isUnsafe = true;
+ DEBUG(dbgs() << " Transformation preventing inst: " << *User << '\n');
+ }
bool isSafeAllocaToScalarRepl(AllocaInst *AI);
- void isSafeForScalarRepl(Instruction *I, AllocaInst *AI, uint64_t Offset,
- AllocaInfo &Info);
- void isSafeGEP(GetElementPtrInst *GEPI, AllocaInst *AI, uint64_t &Offset,
- AllocaInfo &Info);
- void isSafeMemAccess(AllocaInst *AI, uint64_t Offset, uint64_t MemSize,
- const Type *MemOpType, bool isStore, AllocaInfo &Info);
+ void isSafeForScalarRepl(Instruction *I, uint64_t Offset, AllocaInfo &Info);
+ void isSafePHISelectUseForScalarRepl(Instruction *User, uint64_t Offset,
+ AllocaInfo &Info);
+ void isSafeGEP(GetElementPtrInst *GEPI, uint64_t &Offset, AllocaInfo &Info);
+ void isSafeMemAccess(uint64_t Offset, uint64_t MemSize,
+ const Type *MemOpType, bool isStore, AllocaInfo &Info,
+ Instruction *TheAccess, bool AllowWholeAccess);
bool TypeHasComponent(const Type *T, uint64_t Offset, uint64_t Size);
uint64_t FindElementAndOffset(const Type *&T, uint64_t &Offset,
const Type *&IdxTy);
-
- void DoScalarReplacement(AllocaInst *AI,
+
+ void DoScalarReplacement(AllocaInst *AI,
std::vector<AllocaInst*> &WorkList);
void DeleteDeadInstructions();
- AllocaInst *AddNewAlloca(Function &F, const Type *Ty, AllocaInst *Base);
-
+
void RewriteForScalarRepl(Instruction *I, AllocaInst *AI, uint64_t Offset,
SmallVector<AllocaInst*, 32> &NewElts);
void RewriteBitCast(BitCastInst *BC, AllocaInst *AI, uint64_t Offset,
SmallVector<AllocaInst*, 32> &NewElts);
void RewriteLoadUserOfWholeAlloca(LoadInst *LI, AllocaInst *AI,
SmallVector<AllocaInst*, 32> &NewElts);
-
+
static MemTransferInst *isOnlyCopiedFromConstantGlobal(AllocaInst *AI);
};
+
+ // SROA_DT - SROA that uses DominatorTree.
+ struct SROA_DT : public SROA {
+ static char ID;
+ public:
+ SROA_DT(int T = -1) : SROA(T, true, ID) {
+ initializeSROA_DTPass(*PassRegistry::getPassRegistry());
+ }
+
+ // getAnalysisUsage - This pass does not require any passes, but we know it
+ // will not alter the CFG, so say so.
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.addRequired<DominatorTree>();
+ AU.setPreservesCFG();
+ }
+ };
+
+ // SROA_SSAUp - SROA that uses SSAUpdater.
+ struct SROA_SSAUp : public SROA {
+ static char ID;
+ public:
+ SROA_SSAUp(int T = -1) : SROA(T, false, ID) {
+ initializeSROA_SSAUpPass(*PassRegistry::getPassRegistry());
+ }
+
+ // getAnalysisUsage - This pass does not require any passes, but we know it
+ // will not alter the CFG, so say so.
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.setPreservesCFG();
+ }
+ };
+
}
-char SROA::ID = 0;
-static RegisterPass<SROA> X("scalarrepl", "Scalar Replacement of Aggregates");
+char SROA_DT::ID = 0;
+char SROA_SSAUp::ID = 0;
+
+INITIALIZE_PASS_BEGIN(SROA_DT, "scalarrepl",
+ "Scalar Replacement of Aggregates (DT)", false, false)
+INITIALIZE_PASS_DEPENDENCY(DominatorTree)
+INITIALIZE_PASS_END(SROA_DT, "scalarrepl",
+ "Scalar Replacement of Aggregates (DT)", false, false)
+
+INITIALIZE_PASS_BEGIN(SROA_SSAUp, "scalarrepl-ssa",
+ "Scalar Replacement of Aggregates (SSAUp)", false, false)
+INITIALIZE_PASS_END(SROA_SSAUp, "scalarrepl-ssa",
+ "Scalar Replacement of Aggregates (SSAUp)", false, false)
// Public interface to the ScalarReplAggregates pass
-FunctionPass *llvm::createScalarReplAggregatesPass(signed int Threshold) {
- return new SROA(Threshold);
+FunctionPass *llvm::createScalarReplAggregatesPass(int Threshold,
+ bool UseDomTree) {
+ if (UseDomTree)
+ return new SROA_DT(Threshold);
+ return new SROA_SSAUp(Threshold);
}
/// optimization, which scans the uses of an alloca and determines if it can
/// rewrite it in terms of a single new alloca that can be mem2reg'd.
class ConvertToScalarInfo {
- /// AllocaSize - The size of the alloca being considered.
+ /// AllocaSize - The size of the alloca being considered in bytes.
unsigned AllocaSize;
const TargetData &TD;
-
- /// IsNotTrivial - This is set to true if there is somee access to the object
+
+ /// IsNotTrivial - This is set to true if there is some access to the object
/// which means that mem2reg can't promote it.
bool IsNotTrivial;
-
+
/// VectorTy - This tracks the type that we should promote the vector to if
/// it is possible to turn it into a vector. This starts out null, and if it
/// isn't possible to turn into a vector type, it gets set to VoidTy.
const Type *VectorTy;
-
+
/// HadAVector - True if there is at least one vector access to the alloca.
/// We don't want to turn random arrays into vectors and use vector element
/// insert/extract, but if there are element accesses to something that is
/// also declared as a vector, we do want to promote to a vector.
bool HadAVector;
+ /// HadNonMemTransferAccess - True if there is at least one access to the
+ /// alloca that is not a MemTransferInst. We don't want to turn structs into
+ /// large integers unless there is some potential for optimization.
+ bool HadNonMemTransferAccess;
+
public:
explicit ConvertToScalarInfo(unsigned Size, const TargetData &td)
- : AllocaSize(Size), TD(td) {
- IsNotTrivial = false;
- VectorTy = 0;
- HadAVector = false;
- }
-
+ : AllocaSize(Size), TD(td), IsNotTrivial(false), VectorTy(0),
+ HadAVector(false), HadNonMemTransferAccess(false) { }
+
AllocaInst *TryConvert(AllocaInst *AI);
-
+
private:
bool CanConvertToScalar(Value *V, uint64_t Offset);
- void MergeInType(const Type *In, uint64_t Offset);
+ void MergeInType(const Type *In, uint64_t Offset, bool IsLoadOrStore);
+ bool MergeInVectorType(const VectorType *VInTy, 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,
};
} // end anonymous namespace.
+
/// TryConvert - Analyze the specified alloca, and if it is safe to do so,
/// rewrite it to be a new alloca which is mem2reg'able. This returns the new
/// alloca if possible or null if not.
// out.
if (!CanConvertToScalar(AI, 0) || !IsNotTrivial)
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
<< *VectorTy << '\n');
NewTy = VectorTy; // Use the vector type.
} else {
+ unsigned BitWidth = AllocaSize * 8;
+ if (!HadAVector && !HadNonMemTransferAccess &&
+ !TD.fitsInLegalInteger(BitWidth))
+ return 0;
+
DEBUG(dbgs() << "CONVERT TO SCALAR INTEGER: " << *AI << "\n");
// Create and insert the integer alloca.
- NewTy = IntegerType::get(AI->getContext(), AllocaSize*8);
+ NewTy = IntegerType::get(AI->getContext(), BitWidth);
}
AllocaInst *NewAI = new AllocaInst(NewTy, 0, "", AI->getParent()->begin());
ConvertUsesToScalar(AI, NewAI, 0);
/// MergeInType - Add the 'In' type to the accumulated vector type (VectorTy)
/// so far at the offset specified by Offset (which is specified in bytes).
///
-/// There are two cases we handle here:
+/// There are three 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
+/// 2) A union of vector types with power-of-2 size differences, e.g. a float,
+/// <2 x float> and <4 x float>. Here we turn element accesses into insert
+/// and extract element operations, and <2 x float> accesses into a cast to
+/// <2 x double>, an extract, and a cast back to <2 x float>.
+/// 3) 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. We mark this by setting VectorTy
/// to VoidTy.
-void ConvertToScalarInfo::MergeInType(const Type *In, uint64_t Offset) {
+void ConvertToScalarInfo::MergeInType(const Type *In, uint64_t Offset,
+ bool IsLoadOrStore) {
// If we already decided to turn this into a blob of integer memory, there is
// nothing to be done.
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)) {
- // Remember if we saw a vector type.
- HadAVector = true;
-
- 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 this is a subsequent access, ignore it
- // even if it is a differing type but the same size. Worst case we can
- // bitcast the resultant vectors.
- if (VectorTy == 0)
- VectorTy = VInTy;
+ if (MergeInVectorType(VInTy, Offset))
return;
- }
} else if (In->isFloatTy() || In->isDoubleTy() ||
(In->isIntegerTy() && In->getPrimitiveSizeInBits() >= 8 &&
isPowerOf2_32(In->getPrimitiveSizeInBits()))) {
+ // Full width accesses can be ignored, because they can always be turned
+ // into bitcasts.
+ unsigned EltSize = In->getPrimitiveSizeInBits()/8;
+ if (IsLoadOrStore && EltSize == AllocaSize)
+ return;
// 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 ||
+ (VectorTy == 0 ||
cast<VectorType>(VectorTy)->getElementType()
->getPrimitiveSizeInBits()/8 == EltSize)) {
if (VectorTy == 0)
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());
}
+/// MergeInVectorType - Handles the vector case of MergeInType, returning true
+/// if the type was successfully merged and false otherwise.
+bool ConvertToScalarInfo::MergeInVectorType(const VectorType *VInTy,
+ uint64_t Offset) {
+ // Remember if we saw a vector type.
+ HadAVector = true;
+
+ // TODO: Support nonzero offsets?
+ if (Offset != 0)
+ return false;
+
+ // Only allow vectors that are a power-of-2 away from the size of the alloca.
+ if (!isPowerOf2_64(AllocaSize / (VInTy->getBitWidth() / 8)))
+ return false;
+
+ // If this the first vector we see, remember the type so that we know the
+ // element size.
+ if (!VectorTy) {
+ VectorTy = VInTy;
+ return true;
+ }
+
+ unsigned BitWidth = cast<VectorType>(VectorTy)->getBitWidth();
+ unsigned InBitWidth = VInTy->getBitWidth();
+
+ // Vectors of the same size can be converted using a simple bitcast.
+ if (InBitWidth == BitWidth && AllocaSize == (InBitWidth / 8))
+ return true;
+
+ const Type *ElementTy = cast<VectorType>(VectorTy)->getElementType();
+ const Type *InElementTy = cast<VectorType>(VInTy)->getElementType();
+
+ // Do not allow mixed integer and floating-point accesses from vectors of
+ // different sizes.
+ if (ElementTy->isFloatingPointTy() != InElementTy->isFloatingPointTy())
+ return false;
+
+ if (ElementTy->isFloatingPointTy()) {
+ // Only allow floating-point vectors of different sizes if they have the
+ // same element type.
+ // TODO: This could be loosened a bit, but would anything benefit?
+ if (ElementTy != InElementTy)
+ return false;
+
+ // There are no arbitrary-precision floating-point types, which limits the
+ // number of legal vector types with larger element types that we can form
+ // to bitcast and extract a subvector.
+ // TODO: We could support some more cases with mixed fp128 and double here.
+ if (!(BitWidth == 64 || BitWidth == 128) ||
+ !(InBitWidth == 64 || InBitWidth == 128))
+ return false;
+ } else {
+ assert(ElementTy->isIntegerTy() && "Vector elements must be either integer "
+ "or floating-point.");
+ unsigned BitWidth = ElementTy->getPrimitiveSizeInBits();
+ unsigned InBitWidth = InElementTy->getPrimitiveSizeInBits();
+
+ // Do not allow integer types smaller than a byte or types whose widths are
+ // not a multiple of a byte.
+ if (BitWidth < 8 || InBitWidth < 8 ||
+ BitWidth % 8 != 0 || InBitWidth % 8 != 0)
+ return false;
+ }
+
+ // Pick the largest of the two vector types.
+ if (InBitWidth > BitWidth)
+ VectorTy = VInTy;
+
+ return true;
+}
+
/// 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
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);
+ // Don't touch MMX operations.
+ if (LI->getType()->isX86_MMXTy())
+ return false;
+ HadNonMemTransferAccess = true;
+ MergeInType(LI->getType(), Offset, true);
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);
+ // Don't touch MMX operations.
+ if (SI->getOperand(0)->getType()->isX86_MMXTy())
+ return false;
+ HadNonMemTransferAccess = true;
+ MergeInType(SI->getOperand(0)->getType(), Offset, true);
continue;
}
-
+
if (BitCastInst *BCI = dyn_cast<BitCastInst>(User)) {
IsNotTrivial = true; // Can't be mem2reg'd.
if (!CanConvertToScalar(BCI, Offset))
// 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(),
if (!CanConvertToScalar(GEP, Offset+GEPOffset))
return false;
IsNotTrivial = true; // Can't be mem2reg'd.
+ HadNonMemTransferAccess = true;
continue;
}
!isa<ConstantInt>(MSI->getLength()))
return false;
IsNotTrivial = true; // Can't be mem2reg'd.
+ HadNonMemTransferAccess = true;
continue;
}
ConstantInt *Len = dyn_cast<ConstantInt>(MTI->getLength());
if (Len == 0 || Len->getZExtValue() != AllocaSize || Offset != 0)
return false;
-
+
IsNotTrivial = true; // Can't be mem2reg'd.
continue;
}
-
+
// Otherwise, we cannot handle this!
return false;
}
-
+
return true;
}
GEP->eraseFromParent();
continue;
}
-
- IRBuilder<> Builder(User->getParent(), User);
-
+
+ IRBuilder<> Builder(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");
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");
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)) {
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);
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();
+ Old->eraseFromParent();
}
MSI->eraseFromParent();
continue;
// 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) {
+ AllocaInst *OrigAI = cast<AllocaInst>(GetUnderlyingObject(Ptr, &TD, 0));
+
+ if (GetUnderlyingObject(MTI->getSource(), &TD, 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());
-
+ const PointerType* SPTy = cast<PointerType>(SrcPtr->getType());
+ const PointerType* AIPTy = cast<PointerType>(NewAI->getType());
+ if (SPTy->getAddressSpace() != AIPTy->getAddressSpace()) {
+ AIPTy = PointerType::get(AIPTy->getElementType(),
+ SPTy->getAddressSpace());
+ }
+ SrcPtr = Builder.CreateBitCast(SrcPtr, AIPTy);
+
LoadInst *SrcVal = Builder.CreateLoad(SrcPtr, "srcval");
SrcVal->setAlignment(MTI->getAlignment());
Builder.CreateStore(SrcVal, NewAI);
- } else if (MTI->getDest()->getUnderlyingObject(0) != OrigAI) {
+ } else if (GetUnderlyingObject(MTI->getDest(), &TD, 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());
+ const PointerType* DPTy = cast<PointerType>(MTI->getDest()->getType());
+ const PointerType* AIPTy = cast<PointerType>(NewAI->getType());
+ if (DPTy->getAddressSpace() != AIPTy->getAddressSpace()) {
+ AIPTy = PointerType::get(AIPTy->getElementType(),
+ DPTy->getAddressSpace());
+ }
+ Value *DstPtr = Builder.CreateBitCast(MTI->getDest(), AIPTy);
+
StoreInst *NewStore = Builder.CreateStore(SrcVal, DstPtr);
NewStore->setAlignment(MTI->getAlignment());
} else {
MTI->eraseFromParent();
continue;
}
-
+
llvm_unreachable("Unsupported operation!");
}
}
+/// getScaledElementType - Gets a scaled element type for a partial vector
+/// access of an alloca. The input type must be an integer or float, and
+/// the resulting type must be an integer, float or double.
+static const Type *getScaledElementType(const Type *OldTy,
+ unsigned NewBitWidth) {
+ assert((OldTy->isIntegerTy() || OldTy->isFloatTy()) && "Partial vector "
+ "accesses must be scaled from integer or float elements.");
+
+ LLVMContext &Context = OldTy->getContext();
+
+ if (OldTy->isIntegerTy())
+ return Type::getIntNTy(Context, NewBitWidth);
+ if (NewBitWidth == 32)
+ return Type::getFloatTy(Context);
+ if (NewBitWidth == 64)
+ return Type::getDoubleTy(Context);
+
+ llvm_unreachable("Invalid type for a partial vector access of an alloca!");
+}
+
/// 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.
// 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())
+ unsigned ToTypeSize = TD.getTypeAllocSize(ToType);
+ if (ToTypeSize == AllocaSize)
return Builder.CreateBitCast(FromVal, ToType, "tmp");
+ if (ToType->isVectorTy()) {
+ assert(isPowerOf2_64(AllocaSize / ToTypeSize) &&
+ "Partial vector access of an alloca must have a power-of-2 size "
+ "ratio.");
+ assert(Offset == 0 && "Can't extract a value of a smaller vector type "
+ "from a nonzero offset.");
+
+ const Type *ToElementTy = cast<VectorType>(ToType)->getElementType();
+ const Type *CastElementTy = getScaledElementType(ToElementTy,
+ ToTypeSize * 8);
+ unsigned NumCastVectorElements = AllocaSize / ToTypeSize;
+
+ LLVMContext &Context = FromVal->getContext();
+ const Type *CastTy = VectorType::get(CastElementTy,
+ NumCastVectorElements);
+ Value *Cast = Builder.CreateBitCast(FromVal, CastTy, "tmp");
+ Value *Extract = Builder.CreateExtractElement(Cast, ConstantInt::get(
+ Type::getInt32Ty(Context), 0), "tmp");
+ return Builder.CreateBitCast(Extract, ToType, "tmp");
+ }
+
// Otherwise it must be an element access.
unsigned Elt = 0;
if (Offset) {
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)) {
}
return Res;
}
-
+
if (const ArrayType *AT = dyn_cast<ArrayType>(ToType)) {
uint64_t EltSize = TD.getTypeAllocSizeInBits(AT->getElementType());
Value *Res = UndefValue::get(AT);
ConstantInt::get(FromVal->getType(),
ShAmt), "tmp");
else if (ShAmt < 0 && (unsigned)-ShAmt < NTy->getBitWidth())
- FromVal = Builder.CreateShl(FromVal,
+ FromVal = Builder.CreateShl(FromVal,
ConstantInt::get(FromVal->getType(),
-ShAmt), "tmp");
unsigned LIBitWidth = TD.getTypeSizeInBits(ToType);
if (LIBitWidth < NTy->getBitWidth())
FromVal =
- Builder.CreateTrunc(FromVal, IntegerType::get(FromVal->getContext(),
+ Builder.CreateTrunc(FromVal, IntegerType::get(FromVal->getContext(),
LIBitWidth), "tmp");
else if (LIBitWidth > NTy->getBitWidth())
FromVal =
- Builder.CreateZExt(FromVal, IntegerType::get(FromVal->getContext(),
+ Builder.CreateZExt(FromVal, IntegerType::get(FromVal->getContext(),
LIBitWidth), "tmp");
// If the result is an integer, this is a trunc or bitcast.
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");
+ if (SV->getType()->isVectorTy() && isPowerOf2_64(VecSize / ValSize)) {
+ assert(Offset == 0 && "Can't insert a value of a smaller vector type at "
+ "a nonzero offset.");
+
+ const Type *ToElementTy =
+ cast<VectorType>(SV->getType())->getElementType();
+ const Type *CastElementTy = getScaledElementType(ToElementTy, ValSize);
+ unsigned NumCastVectorElements = VecSize / ValSize;
+
+ LLVMContext &Context = SV->getContext();
+ const Type *OldCastTy = VectorType::get(CastElementTy,
+ NumCastVectorElements);
+ Value *OldCast = Builder.CreateBitCast(Old, OldCastTy, "tmp");
+
+ Value *SVCast = Builder.CreateBitCast(SV, CastElementTy, "tmp");
+ Value *Insert =
+ Builder.CreateInsertElement(OldCast, SVCast, ConstantInt::get(
+ Type::getInt32Ty(Context), 0), "tmp");
+ return Builder.CreateBitCast(Insert, 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,
+
+ 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,
+ 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) {
return Changed;
}
+namespace {
+class AllocaPromoter : public LoadAndStorePromoter {
+ AllocaInst *AI;
+public:
+ AllocaPromoter(const SmallVectorImpl<Instruction*> &Insts, SSAUpdater &S)
+ : LoadAndStorePromoter(Insts, S), AI(0) {}
+
+ void run(AllocaInst *AI, const SmallVectorImpl<Instruction*> &Insts) {
+ // Remember which alloca we're promoting (for isInstInList).
+ this->AI = AI;
+ LoadAndStorePromoter::run(Insts);
+ AI->eraseFromParent();
+ }
+
+ virtual bool isInstInList(Instruction *I,
+ const SmallVectorImpl<Instruction*> &Insts) const {
+ if (LoadInst *LI = dyn_cast<LoadInst>(I))
+ return LI->getOperand(0) == AI;
+ return cast<StoreInst>(I)->getPointerOperand() == AI;
+ }
+};
+} // end anon namespace
+
+/// isSafeSelectToSpeculate - Select instructions that use an alloca and are
+/// subsequently loaded can be rewritten to load both input pointers and then
+/// select between the result, allowing the load of the alloca to be promoted.
+/// From this:
+/// %P2 = select i1 %cond, i32* %Alloca, i32* %Other
+/// %V = load i32* %P2
+/// to:
+/// %V1 = load i32* %Alloca -> will be mem2reg'd
+/// %V2 = load i32* %Other
+/// %V = select i1 %cond, i32 %V1, i32 %V2
+///
+/// We can do this to a select if its only uses are loads and if the operand to
+/// the select can be loaded unconditionally.
+static bool isSafeSelectToSpeculate(SelectInst *SI, const TargetData *TD) {
+ bool TDerefable = SI->getTrueValue()->isDereferenceablePointer();
+ bool FDerefable = SI->getFalseValue()->isDereferenceablePointer();
+
+ for (Value::use_iterator UI = SI->use_begin(), UE = SI->use_end();
+ UI != UE; ++UI) {
+ LoadInst *LI = dyn_cast<LoadInst>(*UI);
+ if (LI == 0 || LI->isVolatile()) return false;
+
+ // Both operands to the select need to be dereferencable, either absolutely
+ // (e.g. allocas) or at this point because we can see other accesses to it.
+ if (!TDerefable && !isSafeToLoadUnconditionally(SI->getTrueValue(), LI,
+ LI->getAlignment(), TD))
+ return false;
+ if (!FDerefable && !isSafeToLoadUnconditionally(SI->getFalseValue(), LI,
+ LI->getAlignment(), TD))
+ return false;
+ }
+
+ return true;
+}
+
+/// isSafePHIToSpeculate - PHI instructions that use an alloca and are
+/// subsequently loaded can be rewritten to load both input pointers in the pred
+/// blocks and then PHI the results, allowing the load of the alloca to be
+/// promoted.
+/// From this:
+/// %P2 = phi [i32* %Alloca, i32* %Other]
+/// %V = load i32* %P2
+/// to:
+/// %V1 = load i32* %Alloca -> will be mem2reg'd
+/// ...
+/// %V2 = load i32* %Other
+/// ...
+/// %V = phi [i32 %V1, i32 %V2]
+///
+/// We can do this to a select if its only uses are loads and if the operand to
+/// the select can be loaded unconditionally.
+static bool isSafePHIToSpeculate(PHINode *PN, const TargetData *TD) {
+ // For now, we can only do this promotion if the load is in the same block as
+ // the PHI, and if there are no stores between the phi and load.
+ // TODO: Allow recursive phi users.
+ // TODO: Allow stores.
+ BasicBlock *BB = PN->getParent();
+ unsigned MaxAlign = 0;
+ for (Value::use_iterator UI = PN->use_begin(), UE = PN->use_end();
+ UI != UE; ++UI) {
+ LoadInst *LI = dyn_cast<LoadInst>(*UI);
+ if (LI == 0 || LI->isVolatile()) return false;
+
+ // For now we only allow loads in the same block as the PHI. This is a
+ // common case that happens when instcombine merges two loads through a PHI.
+ if (LI->getParent() != BB) return false;
+
+ // Ensure that there are no instructions between the PHI and the load that
+ // could store.
+ for (BasicBlock::iterator BBI = PN; &*BBI != LI; ++BBI)
+ if (BBI->mayWriteToMemory())
+ return false;
+
+ MaxAlign = std::max(MaxAlign, LI->getAlignment());
+ }
+
+ // Okay, we know that we have one or more loads in the same block as the PHI.
+ // We can transform this if it is safe to push the loads into the predecessor
+ // blocks. The only thing to watch out for is that we can't put a possibly
+ // trapping load in the predecessor if it is a critical edge.
+ for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
+ BasicBlock *Pred = PN->getIncomingBlock(i);
+
+ // If the predecessor has a single successor, then the edge isn't critical.
+ if (Pred->getTerminator()->getNumSuccessors() == 1)
+ continue;
+
+ Value *InVal = PN->getIncomingValue(i);
+
+ // If the InVal is an invoke in the pred, we can't put a load on the edge.
+ if (InvokeInst *II = dyn_cast<InvokeInst>(InVal))
+ if (II->getParent() == Pred)
+ return false;
+
+ // If this pointer is always safe to load, or if we can prove that there is
+ // already a load in the block, then we can move the load to the pred block.
+ if (InVal->isDereferenceablePointer() ||
+ isSafeToLoadUnconditionally(InVal, Pred->getTerminator(), MaxAlign, TD))
+ continue;
+
+ return false;
+ }
+
+ return true;
+}
+
+
+/// tryToMakeAllocaBePromotable - This returns true if the alloca only has
+/// direct (non-volatile) loads and stores to it. If the alloca is close but
+/// not quite there, this will transform the code to allow promotion. As such,
+/// it is a non-pure predicate.
+static bool tryToMakeAllocaBePromotable(AllocaInst *AI, const TargetData *TD) {
+ SetVector<Instruction*, SmallVector<Instruction*, 4>,
+ SmallPtrSet<Instruction*, 4> > InstsToRewrite;
+
+ for (Value::use_iterator UI = AI->use_begin(), UE = AI->use_end();
+ UI != UE; ++UI) {
+ User *U = *UI;
+ if (LoadInst *LI = dyn_cast<LoadInst>(U)) {
+ if (LI->isVolatile())
+ return false;
+ continue;
+ }
+
+ if (StoreInst *SI = dyn_cast<StoreInst>(U)) {
+ if (SI->getOperand(0) == AI || SI->isVolatile())
+ return false; // Don't allow a store OF the AI, only INTO the AI.
+ continue;
+ }
+
+ if (SelectInst *SI = dyn_cast<SelectInst>(U)) {
+ // If the condition being selected on is a constant, fold the select, yes
+ // this does (rarely) happen early on.
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(SI->getCondition())) {
+ Value *Result = SI->getOperand(1+CI->isZero());
+ SI->replaceAllUsesWith(Result);
+ SI->eraseFromParent();
+
+ // This is very rare and we just scrambled the use list of AI, start
+ // over completely.
+ return tryToMakeAllocaBePromotable(AI, TD);
+ }
+
+ // If it is safe to turn "load (select c, AI, ptr)" into a select of two
+ // loads, then we can transform this by rewriting the select.
+ if (!isSafeSelectToSpeculate(SI, TD))
+ return false;
+
+ InstsToRewrite.insert(SI);
+ continue;
+ }
+
+ if (PHINode *PN = dyn_cast<PHINode>(U)) {
+ if (PN->use_empty()) { // Dead PHIs can be stripped.
+ InstsToRewrite.insert(PN);
+ continue;
+ }
+
+ // If it is safe to turn "load (phi [AI, ptr, ...])" into a PHI of loads
+ // in the pred blocks, then we can transform this by rewriting the PHI.
+ if (!isSafePHIToSpeculate(PN, TD))
+ return false;
+
+ InstsToRewrite.insert(PN);
+ continue;
+ }
+
+ return false;
+ }
+
+ // If there are no instructions to rewrite, then all uses are load/stores and
+ // we're done!
+ if (InstsToRewrite.empty())
+ return true;
+
+ // If we have instructions that need to be rewritten for this to be promotable
+ // take care of it now.
+ for (unsigned i = 0, e = InstsToRewrite.size(); i != e; ++i) {
+ if (SelectInst *SI = dyn_cast<SelectInst>(InstsToRewrite[i])) {
+ // Selects in InstsToRewrite only have load uses. Rewrite each as two
+ // loads with a new select.
+ while (!SI->use_empty()) {
+ LoadInst *LI = cast<LoadInst>(SI->use_back());
+
+ IRBuilder<> Builder(LI);
+ LoadInst *TrueLoad =
+ Builder.CreateLoad(SI->getTrueValue(), LI->getName()+".t");
+ LoadInst *FalseLoad =
+ Builder.CreateLoad(SI->getFalseValue(), LI->getName()+".t");
+
+ // Transfer alignment and TBAA info if present.
+ TrueLoad->setAlignment(LI->getAlignment());
+ FalseLoad->setAlignment(LI->getAlignment());
+ if (MDNode *Tag = LI->getMetadata(LLVMContext::MD_tbaa)) {
+ TrueLoad->setMetadata(LLVMContext::MD_tbaa, Tag);
+ FalseLoad->setMetadata(LLVMContext::MD_tbaa, Tag);
+ }
+
+ Value *V = Builder.CreateSelect(SI->getCondition(), TrueLoad, FalseLoad);
+ V->takeName(LI);
+ LI->replaceAllUsesWith(V);
+ LI->eraseFromParent();
+ }
+
+ // Now that all the loads are gone, the select is gone too.
+ SI->eraseFromParent();
+ continue;
+ }
+
+ // Otherwise, we have a PHI node which allows us to push the loads into the
+ // predecessors.
+ PHINode *PN = cast<PHINode>(InstsToRewrite[i]);
+ if (PN->use_empty()) {
+ PN->eraseFromParent();
+ continue;
+ }
+
+ const Type *LoadTy = cast<PointerType>(PN->getType())->getElementType();
+ PHINode *NewPN = PHINode::Create(LoadTy, PN->getNumIncomingValues(),
+ PN->getName()+".ld", PN);
+
+ // Get the TBAA tag and alignment to use from one of the loads. It doesn't
+ // matter which one we get and if any differ, it doesn't matter.
+ LoadInst *SomeLoad = cast<LoadInst>(PN->use_back());
+ MDNode *TBAATag = SomeLoad->getMetadata(LLVMContext::MD_tbaa);
+ unsigned Align = SomeLoad->getAlignment();
+
+ // Rewrite all loads of the PN to use the new PHI.
+ while (!PN->use_empty()) {
+ LoadInst *LI = cast<LoadInst>(PN->use_back());
+ LI->replaceAllUsesWith(NewPN);
+ LI->eraseFromParent();
+ }
+
+ // Inject loads into all of the pred blocks. Keep track of which blocks we
+ // insert them into in case we have multiple edges from the same block.
+ DenseMap<BasicBlock*, LoadInst*> InsertedLoads;
+
+ for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
+ BasicBlock *Pred = PN->getIncomingBlock(i);
+ LoadInst *&Load = InsertedLoads[Pred];
+ if (Load == 0) {
+ Load = new LoadInst(PN->getIncomingValue(i),
+ PN->getName() + "." + Pred->getName(),
+ Pred->getTerminator());
+ Load->setAlignment(Align);
+ if (TBAATag) Load->setMetadata(LLVMContext::MD_tbaa, TBAATag);
+ }
+
+ NewPN->addIncoming(Load, Pred);
+ }
+
+ PN->eraseFromParent();
+ }
+
+ ++NumAdjusted;
+ return true;
+}
+
bool SROA::performPromotion(Function &F) {
std::vector<AllocaInst*> Allocas;
- DominatorTree &DT = getAnalysis<DominatorTree>();
- DominanceFrontier &DF = getAnalysis<DominanceFrontier>();
+ DominatorTree *DT = 0;
+ if (HasDomTree)
+ DT = &getAnalysis<DominatorTree>();
BasicBlock &BB = F.getEntryBlock(); // Get the entry node for the function
bool Changed = false;
-
+ SmallVector<Instruction*, 64> Insts;
while (1) {
Allocas.clear();
// the entry node
for (BasicBlock::iterator I = BB.begin(), E = --BB.end(); I != E; ++I)
if (AllocaInst *AI = dyn_cast<AllocaInst>(I)) // Is it an alloca?
- if (isAllocaPromotable(AI))
+ if (tryToMakeAllocaBePromotable(AI, TD))
Allocas.push_back(AI);
if (Allocas.empty()) break;
- PromoteMemToReg(Allocas, DT, DF);
+ if (HasDomTree)
+ PromoteMemToReg(Allocas, *DT);
+ else {
+ SSAUpdater SSA;
+ for (unsigned i = 0, e = Allocas.size(); i != e; ++i) {
+ AllocaInst *AI = Allocas[i];
+
+ // Build list of instructions to promote.
+ for (Value::use_iterator UI = AI->use_begin(), E = AI->use_end();
+ UI != E; ++UI)
+ Insts.push_back(cast<Instruction>(*UI));
+
+ AllocaPromoter(Insts, SSA).run(AI, Insts);
+ Insts.clear();
+ }
+ }
NumPromoted += Allocas.size();
Changed = true;
}
while (!WorkList.empty()) {
AllocaInst *AI = WorkList.back();
WorkList.pop_back();
-
+
// Handle dead allocas trivially. These can be formed by SROA'ing arrays
// with unused elements.
if (AI->use_empty()) {
// If this alloca is impossible for us to promote, reject it early.
if (AI->isArrayAllocation() || !AI->getAllocatedType()->isSized())
continue;
-
+
// Check to see if this allocation is only modified by a memcpy/memmove from
// a constant global. If this is the case, we can change all users to use
// the constant global instead. This is commonly produced by the CFE by
Changed = true;
continue;
}
-
+
// Check to see if we can perform the core SROA transformation. We cannot
// transform the allocation instruction if it is an array allocation
// (allocations OF arrays are ok though), and an allocation of a scalar
// Do not promote [0 x %struct].
if (AllocaSize == 0) continue;
-
+
// Do not promote any struct whose size is too big.
if (AllocaSize > SRThreshold) continue;
-
+
// If the alloca looks like a good candidate for scalar replacement, and if
// all its users can be transformed, then split up the aggregate into its
// separate elements.
++NumConverted;
Changed = true;
continue;
- }
-
+ }
+
// Otherwise, couldn't process this alloca.
}
/// DoScalarReplacement - This alloca satisfied the isSafeAllocaToScalarRepl
/// predicate, do SROA now.
-void SROA::DoScalarReplacement(AllocaInst *AI,
+void SROA::DoScalarReplacement(AllocaInst *AI,
std::vector<AllocaInst*> &WorkList) {
DEBUG(dbgs() << "Found inst to SROA: " << *AI << '\n');
SmallVector<AllocaInst*, 32> ElementAllocas;
if (const StructType *ST = dyn_cast<StructType>(AI->getAllocatedType())) {
ElementAllocas.reserve(ST->getNumContainedTypes());
for (unsigned i = 0, e = ST->getNumContainedTypes(); i != e; ++i) {
- AllocaInst *NA = new AllocaInst(ST->getContainedType(i), 0,
+ AllocaInst *NA = new AllocaInst(ST->getContainedType(i), 0,
AI->getAlignment(),
AI->getName() + "." + Twine(i), AI);
ElementAllocas.push_back(NA);
DeleteDeadInstructions();
AI->eraseFromParent();
- NumReplaced++;
+ ++NumReplaced;
}
/// DeleteDeadInstructions - Erase instructions on the DeadInstrs list,
I->eraseFromParent();
}
}
-
+
/// isSafeForScalarRepl - Check if instruction I is a safe use with regard to
/// performing scalar replacement of alloca AI. The results are flagged in
/// the Info parameter. Offset indicates the position within AI that is
/// referenced by this instruction.
-void SROA::isSafeForScalarRepl(Instruction *I, AllocaInst *AI, uint64_t Offset,
+void SROA::isSafeForScalarRepl(Instruction *I, uint64_t Offset,
AllocaInfo &Info) {
for (Value::use_iterator UI = I->use_begin(), E = I->use_end(); UI!=E; ++UI) {
Instruction *User = cast<Instruction>(*UI);
if (BitCastInst *BC = dyn_cast<BitCastInst>(User)) {
- isSafeForScalarRepl(BC, AI, Offset, Info);
+ isSafeForScalarRepl(BC, Offset, Info);
} else if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(User)) {
uint64_t GEPOffset = Offset;
- isSafeGEP(GEPI, AI, GEPOffset, Info);
+ isSafeGEP(GEPI, GEPOffset, Info);
if (!Info.isUnsafe)
- isSafeForScalarRepl(GEPI, AI, GEPOffset, Info);
+ isSafeForScalarRepl(GEPI, GEPOffset, Info);
} else if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(User)) {
ConstantInt *Length = dyn_cast<ConstantInt>(MI->getLength());
- if (Length)
- isSafeMemAccess(AI, Offset, Length->getZExtValue(), 0,
- UI.getOperandNo() == 0, Info);
- else
- MarkUnsafe(Info);
+ if (Length == 0)
+ return MarkUnsafe(Info, User);
+ isSafeMemAccess(Offset, Length->getZExtValue(), 0,
+ UI.getOperandNo() == 0, Info, MI,
+ true /*AllowWholeAccess*/);
} else if (LoadInst *LI = dyn_cast<LoadInst>(User)) {
- if (!LI->isVolatile()) {
- const Type *LIType = LI->getType();
- isSafeMemAccess(AI, Offset, TD->getTypeAllocSize(LIType),
- LIType, false, Info);
- } else
- MarkUnsafe(Info);
+ if (LI->isVolatile())
+ return MarkUnsafe(Info, User);
+ const Type *LIType = LI->getType();
+ isSafeMemAccess(Offset, TD->getTypeAllocSize(LIType),
+ LIType, false, Info, LI, true /*AllowWholeAccess*/);
+ Info.hasALoadOrStore = true;
+
} else if (StoreInst *SI = dyn_cast<StoreInst>(User)) {
// Store is ok if storing INTO the pointer, not storing the pointer
- if (!SI->isVolatile() && SI->getOperand(0) != I) {
- const Type *SIType = SI->getOperand(0)->getType();
- isSafeMemAccess(AI, Offset, TD->getTypeAllocSize(SIType),
- SIType, true, Info);
- } else
- MarkUnsafe(Info);
+ if (SI->isVolatile() || SI->getOperand(0) == I)
+ return MarkUnsafe(Info, User);
+
+ const Type *SIType = SI->getOperand(0)->getType();
+ isSafeMemAccess(Offset, TD->getTypeAllocSize(SIType),
+ SIType, true, Info, SI, true /*AllowWholeAccess*/);
+ Info.hasALoadOrStore = true;
+ } else if (isa<PHINode>(User) || isa<SelectInst>(User)) {
+ isSafePHISelectUseForScalarRepl(User, Offset, Info);
} else {
- DEBUG(errs() << " Transformation preventing inst: " << *User << '\n');
- MarkUnsafe(Info);
+ return MarkUnsafe(Info, User);
+ }
+ if (Info.isUnsafe) return;
+ }
+}
+
+
+/// isSafePHIUseForScalarRepl - If we see a PHI node or select using a pointer
+/// derived from the alloca, we can often still split the alloca into elements.
+/// This is useful if we have a large alloca where one element is phi'd
+/// together somewhere: we can SRoA and promote all the other elements even if
+/// we end up not being able to promote this one.
+///
+/// All we require is that the uses of the PHI do not index into other parts of
+/// the alloca. The most important use case for this is single load and stores
+/// that are PHI'd together, which can happen due to code sinking.
+void SROA::isSafePHISelectUseForScalarRepl(Instruction *I, uint64_t Offset,
+ AllocaInfo &Info) {
+ // If we've already checked this PHI, don't do it again.
+ if (PHINode *PN = dyn_cast<PHINode>(I))
+ if (!Info.CheckedPHIs.insert(PN))
+ return;
+
+ for (Value::use_iterator UI = I->use_begin(), E = I->use_end(); UI!=E; ++UI) {
+ Instruction *User = cast<Instruction>(*UI);
+
+ if (BitCastInst *BC = dyn_cast<BitCastInst>(User)) {
+ isSafePHISelectUseForScalarRepl(BC, Offset, Info);
+ } else if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(User)) {
+ // Only allow "bitcast" GEPs for simplicity. We could generalize this,
+ // but would have to prove that we're staying inside of an element being
+ // promoted.
+ if (!GEPI->hasAllZeroIndices())
+ return MarkUnsafe(Info, User);
+ isSafePHISelectUseForScalarRepl(GEPI, Offset, Info);
+ } else if (LoadInst *LI = dyn_cast<LoadInst>(User)) {
+ if (LI->isVolatile())
+ return MarkUnsafe(Info, User);
+ const Type *LIType = LI->getType();
+ isSafeMemAccess(Offset, TD->getTypeAllocSize(LIType),
+ LIType, false, Info, LI, false /*AllowWholeAccess*/);
+ Info.hasALoadOrStore = true;
+
+ } else if (StoreInst *SI = dyn_cast<StoreInst>(User)) {
+ // Store is ok if storing INTO the pointer, not storing the pointer
+ if (SI->isVolatile() || SI->getOperand(0) == I)
+ return MarkUnsafe(Info, User);
+
+ const Type *SIType = SI->getOperand(0)->getType();
+ isSafeMemAccess(Offset, TD->getTypeAllocSize(SIType),
+ SIType, true, Info, SI, false /*AllowWholeAccess*/);
+ Info.hasALoadOrStore = true;
+ } else if (isa<PHINode>(User) || isa<SelectInst>(User)) {
+ isSafePHISelectUseForScalarRepl(User, Offset, Info);
+ } else {
+ return MarkUnsafe(Info, User);
}
if (Info.isUnsafe) return;
}
/// references, and when the resulting offset corresponds to an element within
/// the alloca type. The results are flagged in the Info parameter. Upon
/// return, Offset is adjusted as specified by the GEP indices.
-void SROA::isSafeGEP(GetElementPtrInst *GEPI, AllocaInst *AI,
+void SROA::isSafeGEP(GetElementPtrInst *GEPI,
uint64_t &Offset, AllocaInfo &Info) {
gep_type_iterator GEPIt = gep_type_begin(GEPI), E = gep_type_end(GEPI);
if (GEPIt == E)
ConstantInt *IdxVal = dyn_cast<ConstantInt>(GEPIt.getOperand());
if (!IdxVal)
- return MarkUnsafe(Info);
+ return MarkUnsafe(Info, GEPI);
}
// Compute the offset due to this GEP and check if the alloca has a
SmallVector<Value*, 8> Indices(GEPI->op_begin() + 1, GEPI->op_end());
Offset += TD->getIndexedOffset(GEPI->getPointerOperandType(),
&Indices[0], Indices.size());
- if (!TypeHasComponent(AI->getAllocatedType(), Offset, 0))
- MarkUnsafe(Info);
+ if (!TypeHasComponent(Info.AI->getAllocatedType(), Offset, 0))
+ MarkUnsafe(Info, GEPI);
+}
+
+/// isHomogeneousAggregate - Check if type T is a struct or array containing
+/// elements of the same type (which is always true for arrays). If so,
+/// return true with NumElts and EltTy set to the number of elements and the
+/// element type, respectively.
+static bool isHomogeneousAggregate(const Type *T, unsigned &NumElts,
+ const Type *&EltTy) {
+ if (const ArrayType *AT = dyn_cast<ArrayType>(T)) {
+ NumElts = AT->getNumElements();
+ EltTy = (NumElts == 0 ? 0 : AT->getElementType());
+ return true;
+ }
+ if (const StructType *ST = dyn_cast<StructType>(T)) {
+ NumElts = ST->getNumContainedTypes();
+ EltTy = (NumElts == 0 ? 0 : ST->getContainedType(0));
+ for (unsigned n = 1; n < NumElts; ++n) {
+ if (ST->getContainedType(n) != EltTy)
+ return false;
+ }
+ return true;
+ }
+ return false;
+}
+
+/// isCompatibleAggregate - Check if T1 and T2 are either the same type or are
+/// "homogeneous" aggregates with the same element type and number of elements.
+static bool isCompatibleAggregate(const Type *T1, const Type *T2) {
+ if (T1 == T2)
+ return true;
+
+ unsigned NumElts1, NumElts2;
+ const Type *EltTy1, *EltTy2;
+ if (isHomogeneousAggregate(T1, NumElts1, EltTy1) &&
+ isHomogeneousAggregate(T2, NumElts2, EltTy2) &&
+ NumElts1 == NumElts2 &&
+ EltTy1 == EltTy2)
+ return true;
+
+ return false;
}
/// isSafeMemAccess - Check if a load/store/memcpy operates on the entire AI
/// alloca or has an offset and size that corresponds to a component element
/// within it. The offset checked here may have been formed from a GEP with a
/// pointer bitcasted to a different type.
-void SROA::isSafeMemAccess(AllocaInst *AI, uint64_t Offset, uint64_t MemSize,
+///
+/// If AllowWholeAccess is true, then this allows uses of the entire alloca as a
+/// unit. If false, it only allows accesses known to be in a single element.
+void SROA::isSafeMemAccess(uint64_t Offset, uint64_t MemSize,
const Type *MemOpType, bool isStore,
- AllocaInfo &Info) {
+ AllocaInfo &Info, Instruction *TheAccess,
+ bool AllowWholeAccess) {
// Check if this is a load/store of the entire alloca.
- if (Offset == 0 && MemSize == TD->getTypeAllocSize(AI->getAllocatedType())) {
- bool UsesAggregateType = (MemOpType == AI->getAllocatedType());
- // This is safe for MemIntrinsics (where MemOpType is 0), integer types
- // (which are essentially the same as the MemIntrinsics, especially with
- // regard to copying padding between elements), or references using the
- // aggregate type of the alloca.
- if (!MemOpType || MemOpType->isIntegerTy() || UsesAggregateType) {
- if (!UsesAggregateType) {
- if (isStore)
- Info.isMemCpyDst = true;
- else
- Info.isMemCpySrc = true;
- }
+ if (Offset == 0 && AllowWholeAccess &&
+ MemSize == TD->getTypeAllocSize(Info.AI->getAllocatedType())) {
+ // This can be safe for MemIntrinsics (where MemOpType is 0) and integer
+ // loads/stores (which are essentially the same as the MemIntrinsics with
+ // regard to copying padding between elements). But, if an alloca is
+ // flagged as both a source and destination of such operations, we'll need
+ // to check later for padding between elements.
+ if (!MemOpType || MemOpType->isIntegerTy()) {
+ if (isStore)
+ Info.isMemCpyDst = true;
+ else
+ Info.isMemCpySrc = true;
+ return;
+ }
+ // This is also safe for references using a type that is compatible with
+ // the type of the alloca, so that loads/stores can be rewritten using
+ // insertvalue/extractvalue.
+ if (isCompatibleAggregate(MemOpType, Info.AI->getAllocatedType())) {
+ Info.hasSubelementAccess = true;
return;
}
}
// Check if the offset/size correspond to a component within the alloca type.
- const Type *T = AI->getAllocatedType();
- if (TypeHasComponent(T, Offset, MemSize))
+ const Type *T = Info.AI->getAllocatedType();
+ if (TypeHasComponent(T, Offset, MemSize)) {
+ Info.hasSubelementAccess = true;
return;
+ }
- return MarkUnsafe(Info);
+ return MarkUnsafe(Info, TheAccess);
}
/// TypeHasComponent - Return true if T has a component type with the
/// instruction.
void SROA::RewriteForScalarRepl(Instruction *I, AllocaInst *AI, uint64_t Offset,
SmallVector<AllocaInst*, 32> &NewElts) {
- for (Value::use_iterator UI = I->use_begin(), E = I->use_end(); UI!=E; ++UI) {
- Instruction *User = cast<Instruction>(*UI);
+ for (Value::use_iterator UI = I->use_begin(), E = I->use_end(); UI!=E;) {
+ Use &TheUse = UI.getUse();
+ Instruction *User = cast<Instruction>(*UI++);
if (BitCastInst *BC = dyn_cast<BitCastInst>(User)) {
RewriteBitCast(BC, AI, Offset, NewElts);
- } else if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(User)) {
+ continue;
+ }
+
+ if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(User)) {
RewriteGEP(GEPI, AI, Offset, NewElts);
- } else if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(User)) {
+ continue;
+ }
+
+ if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(User)) {
ConstantInt *Length = dyn_cast<ConstantInt>(MI->getLength());
uint64_t MemSize = Length->getZExtValue();
if (Offset == 0 &&
RewriteMemIntrinUserOfAlloca(MI, I, AI, NewElts);
// Otherwise the intrinsic can only touch a single element and the
// address operand will be updated, so nothing else needs to be done.
- } else if (LoadInst *LI = dyn_cast<LoadInst>(User)) {
+ continue;
+ }
+
+ if (LoadInst *LI = dyn_cast<LoadInst>(User)) {
const Type *LIType = LI->getType();
- if (LIType == AI->getAllocatedType()) {
+
+ if (isCompatibleAggregate(LIType, AI->getAllocatedType())) {
// Replace:
// %res = load { i32, i32 }* %alloc
// with:
// If this is a load of the entire alloca to an integer, rewrite it.
RewriteLoadUserOfWholeAlloca(LI, AI, NewElts);
}
- } else if (StoreInst *SI = dyn_cast<StoreInst>(User)) {
+ continue;
+ }
+
+ if (StoreInst *SI = dyn_cast<StoreInst>(User)) {
Value *Val = SI->getOperand(0);
const Type *SIType = Val->getType();
- if (SIType == AI->getAllocatedType()) {
+ if (isCompatibleAggregate(SIType, AI->getAllocatedType())) {
// Replace:
// store { i32, i32 } %val, { i32, i32 }* %alloc
// with:
// If this is a store of the entire alloca from an integer, rewrite it.
RewriteStoreUserOfWholeAlloca(SI, AI, NewElts);
}
+ continue;
+ }
+
+ if (isa<SelectInst>(User) || isa<PHINode>(User)) {
+ // If we have a PHI user of the alloca itself (as opposed to a GEP or
+ // bitcast) we have to rewrite it. GEP and bitcast uses will be RAUW'd to
+ // the new pointer.
+ if (!isa<AllocaInst>(I)) continue;
+
+ assert(Offset == 0 && NewElts[0] &&
+ "Direct alloca use should have a zero offset");
+
+ // If we have a use of the alloca, we know the derived uses will be
+ // utilizing just the first element of the scalarized result. Insert a
+ // bitcast of the first alloca before the user as required.
+ AllocaInst *NewAI = NewElts[0];
+ BitCastInst *BCI = new BitCastInst(NewAI, AI->getType(), "", NewAI);
+ NewAI->moveBefore(BCI);
+ TheUse = BCI;
+ continue;
}
}
}
// If there is an other pointer, we want to convert it to the same pointer
// type as AI has, so we can GEP through it safely.
if (OtherPtr) {
+ unsigned AddrSpace =
+ cast<PointerType>(OtherPtr->getType())->getAddressSpace();
// Remove bitcasts and all-zero GEPs from OtherPtr. This is an
// optimization, but it's also required to detect the corner case where
// OtherPtr may be a bitcast or GEP that currently being rewritten. (This
// function is only called for mem intrinsics that access the whole
// aggregate, so non-zero GEPs are not an issue here.)
- while (1) {
- if (BitCastInst *BC = dyn_cast<BitCastInst>(OtherPtr)) {
- OtherPtr = BC->getOperand(0);
- continue;
- }
- if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(OtherPtr)) {
- // All zero GEPs are effectively bitcasts.
- if (GEP->hasAllZeroIndices()) {
- OtherPtr = GEP->getOperand(0);
- continue;
- }
- }
- break;
- }
+ OtherPtr = OtherPtr->stripPointerCasts();
+
// Copying the alloca to itself is a no-op: just delete it.
if (OtherPtr == AI || OtherPtr == NewElts[0]) {
// This code will run twice for a no-op memcpy -- once for each operand.
DeadInsts.push_back(MI);
return;
}
-
- if (ConstantExpr *BCE = dyn_cast<ConstantExpr>(OtherPtr))
- if (BCE->getOpcode() == Instruction::BitCast)
- OtherPtr = BCE->getOperand(0);
-
+
// If the pointer is not the right type, insert a bitcast to the right
// type.
- if (OtherPtr->getType() != AI->getType())
- OtherPtr = new BitCastInst(OtherPtr, AI->getType(), OtherPtr->getName(),
- MI);
+ const Type *NewTy =
+ PointerType::get(AI->getType()->getElementType(), AddrSpace);
+
+ if (OtherPtr->getType() != NewTy)
+ OtherPtr = new BitCastInst(OtherPtr, NewTy, OtherPtr->getName(), MI);
}
-
+
// Process each element of the aggregate.
- Value *TheFn = MI->getCalledValue();
- const Type *BytePtrTy = MI->getRawDest()->getType();
bool SROADest = MI->getRawDest() == Inst;
-
+
Constant *Zero = Constant::getNullValue(Type::getInt32Ty(MI->getContext()));
for (unsigned i = 0, e = NewElts.size(); i != e; ++i) {
// If this is a memcpy/memmove, emit a GEP of the other element address.
Value *OtherElt = 0;
unsigned OtherEltAlign = MemAlignment;
-
+
if (OtherPtr) {
Value *Idx[2] = { Zero,
ConstantInt::get(Type::getInt32Ty(MI->getContext()), i) };
const Type *EltTy = cast<SequentialType>(OtherTy)->getElementType();
EltOffset = TD->getTypeAllocSize(EltTy)*i;
}
-
+
// The alignment of the other pointer is the guaranteed alignment of the
// element, which is affected by both the known alignment of the whole
// mem intrinsic and the alignment of the element. If the alignment of
// known alignment is just 4 bytes.
OtherEltAlign = (unsigned)MinAlign(OtherEltAlign, EltOffset);
}
-
+
Value *EltPtr = NewElts[i];
const Type *EltTy = cast<PointerType>(EltPtr->getType())->getElementType();
-
+
// If we got down to a scalar, insert a load or store as appropriate.
if (EltTy->isSingleValueType()) {
if (isa<MemTransferInst>(MI)) {
continue;
}
assert(isa<MemSetInst>(MI));
-
+
// If the stored element is zero (common case), just store a null
// constant.
Constant *StoreVal;
- if (ConstantInt *CI = dyn_cast<ConstantInt>(MI->getOperand(1))) {
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(MI->getArgOperand(1))) {
if (CI->isZero()) {
StoreVal = Constant::getNullValue(EltTy); // 0.0, null, 0, <0,0>
} else {
TotalVal = TotalVal.shl(8);
TotalVal |= OneVal;
}
-
+
// Convert the integer value to the appropriate type.
StoreVal = ConstantInt::get(CI->getContext(), TotalVal);
if (ValTy->isPointerTy())
else if (ValTy->isFloatingPointTy())
StoreVal = ConstantExpr::getBitCast(StoreVal, ValTy);
assert(StoreVal->getType() == ValTy && "Type mismatch!");
-
+
// If the requested value was a vector constant, create it.
if (EltTy != ValTy) {
unsigned NumElts = cast<VectorType>(ValTy)->getNumElements();
SmallVector<Constant*, 16> Elts(NumElts, StoreVal);
- StoreVal = ConstantVector::get(&Elts[0], NumElts);
+ StoreVal = ConstantVector::get(Elts);
}
}
new StoreInst(StoreVal, EltPtr, MI);
// Otherwise, if we're storing a byte variable, use a memset call for
// this element.
}
-
- // Cast the element pointer to BytePtrTy.
- if (EltPtr->getType() != BytePtrTy)
- EltPtr = new BitCastInst(EltPtr, BytePtrTy, EltPtr->getName(), MI);
-
- // Cast the other pointer (if we have one) to BytePtrTy.
- if (OtherElt && OtherElt->getType() != BytePtrTy) {
- // Preserve address space of OtherElt
- const PointerType* OtherPTy = cast<PointerType>(OtherElt->getType());
- const PointerType* PTy = cast<PointerType>(BytePtrTy);
- if (OtherPTy->getElementType() != PTy->getElementType()) {
- Type *NewOtherPTy = PointerType::get(PTy->getElementType(),
- OtherPTy->getAddressSpace());
- OtherElt = new BitCastInst(OtherElt, NewOtherPTy,
- OtherElt->getNameStr(), MI);
- }
- }
-
+
unsigned EltSize = TD->getTypeAllocSize(EltTy);
-
+
+ IRBuilder<> Builder(MI);
+
// Finally, insert the meminst for this element.
- if (isa<MemTransferInst>(MI)) {
- Value *Ops[] = {
- SROADest ? EltPtr : OtherElt, // Dest ptr
- SROADest ? OtherElt : EltPtr, // Src ptr
- ConstantInt::get(MI->getOperand(2)->getType(), EltSize), // Size
- // Align
- ConstantInt::get(Type::getInt32Ty(MI->getContext()), OtherEltAlign),
- MI->getVolatileCst()
- };
- // In case we fold the address space overloaded memcpy of A to B
- // with memcpy of B to C, change the function to be a memcpy of A to C.
- const Type *Tys[] = { Ops[0]->getType(), Ops[1]->getType(),
- Ops[2]->getType() };
- Module *M = MI->getParent()->getParent()->getParent();
- TheFn = Intrinsic::getDeclaration(M, MI->getIntrinsicID(), Tys, 3);
- CallInst::Create(TheFn, Ops, Ops + 5, "", MI);
+ if (isa<MemSetInst>(MI)) {
+ Builder.CreateMemSet(EltPtr, MI->getArgOperand(1), EltSize,
+ MI->isVolatile());
} else {
- assert(isa<MemSetInst>(MI));
- Value *Ops[] = {
- EltPtr, MI->getOperand(1), // Dest, Value,
- ConstantInt::get(MI->getOperand(2)->getType(), EltSize), // Size
- Zero, // Align
- ConstantInt::get(Type::getInt1Ty(MI->getContext()), 0) // isVolatile
- };
- const Type *Tys[] = { Ops[0]->getType(), Ops[2]->getType() };
- Module *M = MI->getParent()->getParent()->getParent();
- TheFn = Intrinsic::getDeclaration(M, Intrinsic::memset, Tys, 2);
- CallInst::Create(TheFn, Ops, Ops + 5, "", MI);
+ assert(isa<MemTransferInst>(MI));
+ Value *Dst = SROADest ? EltPtr : OtherElt; // Dest ptr
+ Value *Src = SROADest ? OtherElt : EltPtr; // Src ptr
+
+ if (isa<MemCpyInst>(MI))
+ Builder.CreateMemCpy(Dst, Src, EltSize, OtherEltAlign,MI->isVolatile());
+ else
+ Builder.CreateMemMove(Dst, Src, EltSize,OtherEltAlign,MI->isVolatile());
}
}
DeadInsts.push_back(MI);
Value *SrcVal = SI->getOperand(0);
const Type *AllocaEltTy = AI->getAllocatedType();
uint64_t AllocaSizeBits = TD->getTypeAllocSizeInBits(AllocaEltTy);
+
+ IRBuilder<> Builder(SI);
// Handle tail padding by extending the operand
if (TD->getTypeSizeInBits(SrcVal->getType()) != AllocaSizeBits)
- SrcVal = new ZExtInst(SrcVal,
- IntegerType::get(SI->getContext(), AllocaSizeBits),
- "", SI);
+ SrcVal = Builder.CreateZExt(SrcVal,
+ IntegerType::get(SI->getContext(), AllocaSizeBits));
DEBUG(dbgs() << "PROMOTING STORE TO WHOLE ALLOCA: " << *AI << '\n' << *SI
<< '\n');
// have different ways to compute the element offset.
if (const StructType *EltSTy = dyn_cast<StructType>(AllocaEltTy)) {
const StructLayout *Layout = TD->getStructLayout(EltSTy);
-
+
for (unsigned i = 0, e = NewElts.size(); i != e; ++i) {
// Get the number of bits to shift SrcVal to get the value.
const Type *FieldTy = EltSTy->getElementType(i);
uint64_t Shift = Layout->getElementOffsetInBits(i);
-
+
if (TD->isBigEndian())
Shift = AllocaSizeBits-Shift-TD->getTypeAllocSizeInBits(FieldTy);
-
+
Value *EltVal = SrcVal;
if (Shift) {
Value *ShiftVal = ConstantInt::get(EltVal->getType(), Shift);
- EltVal = BinaryOperator::CreateLShr(EltVal, ShiftVal,
- "sroa.store.elt", SI);
+ EltVal = Builder.CreateLShr(EltVal, ShiftVal, "sroa.store.elt");
}
-
+
// Truncate down to an integer of the right size.
uint64_t FieldSizeBits = TD->getTypeSizeInBits(FieldTy);
-
+
// Ignore zero sized fields like {}, they obviously contain no data.
if (FieldSizeBits == 0) continue;
-
+
if (FieldSizeBits != AllocaSizeBits)
- EltVal = new TruncInst(EltVal,
- IntegerType::get(SI->getContext(), FieldSizeBits),
- "", SI);
+ EltVal = Builder.CreateTrunc(EltVal,
+ IntegerType::get(SI->getContext(), FieldSizeBits));
Value *DestField = NewElts[i];
if (EltVal->getType() == FieldTy) {
// Storing to an integer field of this size, just do it.
} else if (FieldTy->isFloatingPointTy() || FieldTy->isVectorTy()) {
// Bitcast to the right element type (for fp/vector values).
- EltVal = new BitCastInst(EltVal, FieldTy, "", SI);
+ EltVal = Builder.CreateBitCast(EltVal, FieldTy);
} else {
// Otherwise, bitcast the dest pointer (for aggregates).
- DestField = new BitCastInst(DestField,
- PointerType::getUnqual(EltVal->getType()),
- "", SI);
+ DestField = Builder.CreateBitCast(DestField,
+ PointerType::getUnqual(EltVal->getType()));
}
new StoreInst(EltVal, DestField, SI);
}
-
+
} else {
const ArrayType *ATy = cast<ArrayType>(AllocaEltTy);
const Type *ArrayEltTy = ATy->getElementType();
uint64_t ElementSizeBits = TD->getTypeSizeInBits(ArrayEltTy);
uint64_t Shift;
-
+
if (TD->isBigEndian())
Shift = AllocaSizeBits-ElementOffset;
- else
+ else
Shift = 0;
-
+
for (unsigned i = 0, e = NewElts.size(); i != e; ++i) {
// Ignore zero sized fields like {}, they obviously contain no data.
if (ElementSizeBits == 0) continue;
-
+
Value *EltVal = SrcVal;
if (Shift) {
Value *ShiftVal = ConstantInt::get(EltVal->getType(), Shift);
- EltVal = BinaryOperator::CreateLShr(EltVal, ShiftVal,
- "sroa.store.elt", SI);
+ EltVal = Builder.CreateLShr(EltVal, ShiftVal, "sroa.store.elt");
}
-
+
// Truncate down to an integer of the right size.
if (ElementSizeBits != AllocaSizeBits)
- EltVal = new TruncInst(EltVal,
- IntegerType::get(SI->getContext(),
- ElementSizeBits),"",SI);
+ EltVal = Builder.CreateTrunc(EltVal,
+ IntegerType::get(SI->getContext(),
+ ElementSizeBits));
Value *DestField = NewElts[i];
if (EltVal->getType() == ArrayEltTy) {
// Storing to an integer field of this size, just do it.
} else if (ArrayEltTy->isFloatingPointTy() ||
ArrayEltTy->isVectorTy()) {
// Bitcast to the right element type (for fp/vector values).
- EltVal = new BitCastInst(EltVal, ArrayEltTy, "", SI);
+ EltVal = Builder.CreateBitCast(EltVal, ArrayEltTy);
} else {
// Otherwise, bitcast the dest pointer (for aggregates).
- DestField = new BitCastInst(DestField,
- PointerType::getUnqual(EltVal->getType()),
- "", SI);
+ DestField = Builder.CreateBitCast(DestField,
+ PointerType::getUnqual(EltVal->getType()));
}
new StoreInst(EltVal, DestField, SI);
-
+
if (TD->isBigEndian())
Shift -= ElementOffset;
- else
+ else
Shift += ElementOffset;
}
}
-
+
DeadInsts.push_back(SI);
}
// and form the result value.
const Type *AllocaEltTy = AI->getAllocatedType();
uint64_t AllocaSizeBits = TD->getTypeAllocSizeInBits(AllocaEltTy);
-
+
DEBUG(dbgs() << "PROMOTING LOAD OF WHOLE ALLOCA: " << *AI << '\n' << *LI
<< '\n');
-
+
// There are two forms here: AI could be an array or struct. Both cases
// have different ways to compute the element offset.
const StructLayout *Layout = 0;
} else {
const Type *ArrayEltTy = cast<ArrayType>(AllocaEltTy)->getElementType();
ArrayEltBitOffset = TD->getTypeAllocSizeInBits(ArrayEltTy);
- }
-
- Value *ResultVal =
+ }
+
+ Value *ResultVal =
Constant::getNullValue(IntegerType::get(LI->getContext(), AllocaSizeBits));
-
+
for (unsigned i = 0, e = NewElts.size(); i != e; ++i) {
// Load the value from the alloca. If the NewElt is an aggregate, cast
// the pointer to an integer of the same size before doing the load.
const Type *FieldTy =
cast<PointerType>(SrcField->getType())->getElementType();
uint64_t FieldSizeBits = TD->getTypeSizeInBits(FieldTy);
-
+
// Ignore zero sized fields like {}, they obviously contain no data.
if (FieldSizeBits == 0) continue;
-
- const IntegerType *FieldIntTy = IntegerType::get(LI->getContext(),
+
+ const IntegerType *FieldIntTy = IntegerType::get(LI->getContext(),
FieldSizeBits);
if (!FieldTy->isIntegerTy() && !FieldTy->isFloatingPointTy() &&
!FieldTy->isVectorTy())
// we can shift and insert it.
if (SrcField->getType() != ResultVal->getType())
SrcField = new ZExtInst(SrcField, ResultVal->getType(), "", LI);
-
+
// Determine the number of bits to shift SrcField.
uint64_t Shift;
if (Layout) // Struct case.
Shift = Layout->getElementOffsetInBits(i);
else // Array case.
Shift = i*ArrayEltBitOffset;
-
+
if (TD->isBigEndian())
Shift = AllocaSizeBits-Shift-FieldIntTy->getBitWidth();
-
+
if (Shift) {
Value *ShiftVal = ConstantInt::get(SrcField->getType(), Shift);
SrcField = BinaryOperator::CreateShl(SrcField, ShiftVal, "", LI);
}
- ResultVal = BinaryOperator::CreateOr(SrcField, ResultVal, "", LI);
+ // Don't create an 'or x, 0' on the first iteration.
+ if (!isa<Constant>(ResultVal) ||
+ !cast<Constant>(ResultVal)->isNullValue())
+ ResultVal = BinaryOperator::CreateOr(SrcField, ResultVal, "", LI);
+ else
+ ResultVal = SrcField;
}
// Handle tail padding by truncating the result
}
/// HasPadding - Return true if the specified type has any structure or
-/// alignment padding, false otherwise.
+/// alignment padding in between the elements that would be split apart
+/// by SROA; return false otherwise.
static bool HasPadding(const Type *Ty, const TargetData &TD) {
- if (const StructType *STy = dyn_cast<StructType>(Ty)) {
- const StructLayout *SL = TD.getStructLayout(STy);
- unsigned PrevFieldBitOffset = 0;
- for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) {
- unsigned FieldBitOffset = SL->getElementOffsetInBits(i);
-
- // Padding in sub-elements?
- if (HasPadding(STy->getElementType(i), TD))
- return true;
+ if (const ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
+ Ty = ATy->getElementType();
+ return TD.getTypeSizeInBits(Ty) != TD.getTypeAllocSizeInBits(Ty);
+ }
- // Check to see if there is any padding between this element and the
- // previous one.
- if (i) {
- unsigned PrevFieldEnd =
+ // SROA currently handles only Arrays and Structs.
+ const StructType *STy = cast<StructType>(Ty);
+ const StructLayout *SL = TD.getStructLayout(STy);
+ unsigned PrevFieldBitOffset = 0;
+ for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) {
+ unsigned FieldBitOffset = SL->getElementOffsetInBits(i);
+
+ // Check to see if there is any padding between this element and the
+ // previous one.
+ if (i) {
+ unsigned PrevFieldEnd =
PrevFieldBitOffset+TD.getTypeSizeInBits(STy->getElementType(i-1));
- if (PrevFieldEnd < FieldBitOffset)
- return true;
- }
-
- PrevFieldBitOffset = FieldBitOffset;
- }
-
- // Check for tail padding.
- if (unsigned EltCount = STy->getNumElements()) {
- unsigned PrevFieldEnd = PrevFieldBitOffset +
- TD.getTypeSizeInBits(STy->getElementType(EltCount-1));
- if (PrevFieldEnd < SL->getSizeInBits())
+ if (PrevFieldEnd < FieldBitOffset)
return true;
}
-
- } else if (const ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
- return HasPadding(ATy->getElementType(), TD);
- } else if (const VectorType *VTy = dyn_cast<VectorType>(Ty)) {
- return HasPadding(VTy->getElementType(), TD);
+ PrevFieldBitOffset = FieldBitOffset;
+ }
+ // Check for tail padding.
+ if (unsigned EltCount = STy->getNumElements()) {
+ unsigned PrevFieldEnd = PrevFieldBitOffset +
+ TD.getTypeSizeInBits(STy->getElementType(EltCount-1));
+ if (PrevFieldEnd < SL->getSizeInBits())
+ return true;
}
- return TD.getTypeSizeInBits(Ty) != TD.getTypeAllocSizeInBits(Ty);
+ return false;
}
/// isSafeStructAllocaToScalarRepl - Check to see if the specified allocation of
bool SROA::isSafeAllocaToScalarRepl(AllocaInst *AI) {
// Loop over the use list of the alloca. We can only transform it if all of
// the users are safe to transform.
- AllocaInfo Info;
-
- isSafeForScalarRepl(AI, AI, 0, Info);
+ AllocaInfo Info(AI);
+
+ isSafeForScalarRepl(AI, 0, Info);
if (Info.isUnsafe) {
DEBUG(dbgs() << "Cannot transform: " << *AI << '\n');
return false;
}
-
+
// Okay, we know all the users are promotable. If the aggregate is a memcpy
// source and destination, we have to be careful. In particular, the memcpy
// could be moving around elements that live in structure padding of the LLVM
HasPadding(AI->getAllocatedType(), *TD))
return false;
+ // If the alloca never has an access to just *part* of it, but is accessed
+ // via loads and stores, then we should use ConvertToScalarInfo to promote
+ // the alloca instead of promoting each piece at a time and inserting fission
+ // and fusion code.
+ if (!Info.hasSubelementAccess && Info.hasALoadOrStore) {
+ // If the struct/array just has one element, use basic SRoA.
+ if (const StructType *ST = dyn_cast<StructType>(AI->getAllocatedType())) {
+ if (ST->getNumElements() > 1) return false;
+ } else {
+ if (cast<ArrayType>(AI->getAllocatedType())->getNumElements() > 1)
+ return false;
+ }
+ }
+
return true;
}
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(V))
return GV->isConstant();
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
- if (CE->getOpcode() == Instruction::BitCast ||
+ if (CE->getOpcode() == Instruction::BitCast ||
CE->getOpcode() == Instruction::GetElementPtr)
return PointsToConstantGlobal(CE->getOperand(0));
return false;
/// see any stores or other unknown uses. If we see pointer arithmetic, keep
/// track of whether it moves the pointer (with isOffset) but otherwise traverse
/// the uses. If we see a memcpy/memmove that targets an unoffseted pointer to
-/// the alloca, and if the source pointer is a pointer to a constant global, we
+/// the alloca, and if the source pointer is a pointer to a constant global, we
/// can optimize this.
static bool isOnlyCopiedFromConstantGlobal(Value *V, MemTransferInst *&TheCopy,
bool isOffset) {
for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI!=E; ++UI) {
User *U = cast<Instruction>(*UI);
- if (LoadInst *LI = dyn_cast<LoadInst>(U))
+ if (LoadInst *LI = dyn_cast<LoadInst>(U)) {
// Ignore non-volatile loads, they are always ok.
- if (!LI->isVolatile())
- continue;
-
+ if (LI->isVolatile()) return false;
+ continue;
+ }
+
if (BitCastInst *BCI = dyn_cast<BitCastInst>(U)) {
// If uses of the bitcast are ok, we are ok.
if (!isOnlyCopiedFromConstantGlobal(BCI, TheCopy, isOffset))
return false;
continue;
}
-
+
+ if (CallSite CS = U) {
+ // If this is a readonly/readnone call site, then we know it is just a
+ // load and we can ignore it.
+ if (CS.onlyReadsMemory())
+ continue;
+
+ // If this is the function being called then we treat it like a load and
+ // ignore it.
+ if (CS.isCallee(UI))
+ continue;
+
+ // If this is being passed as a byval argument, the caller is making a
+ // copy, so it is only a read of the alloca.
+ unsigned ArgNo = CS.getArgumentNo(UI);
+ if (CS.paramHasAttr(ArgNo+1, Attribute::ByVal))
+ continue;
+ }
+
// If this is isn't our memcpy/memmove, reject it as something we can't
// handle.
MemTransferInst *MI = dyn_cast<MemTransferInst>(U);
if (MI == 0)
return false;
+ // If the transfer is using the alloca as a source of the transfer, then
+ // ignore it since it is a load (unless the transfer is volatile).
+ if (UI.getOperandNo() == 1) {
+ if (MI->isVolatile()) return false;
+ continue;
+ }
+
// If we already have seen a copy, reject the second one.
if (TheCopy) return false;
-
+
// If the pointer has been offset from the start of the alloca, we can't
// safely handle this.
if (isOffset) return false;
// If the memintrinsic isn't using the alloca as the dest, reject it.
if (UI.getOperandNo() != 0) return false;
-
+
// If the source of the memcpy/move is not a constant global, reject it.
if (!PointsToConstantGlobal(MI->getSource()))
return false;
-
+
// Otherwise, the transform is safe. Remember the copy instruction.
TheCopy = MI;
}
projects / oota-llvm.git / blobdiff