// each member (if possible). Then, if possible, it transforms the individual
// alloca instructions into nice clean scalar SSA form.
//
-// This combines a simple SRoA algorithm with the Mem2Reg algorithm because
+// This combines a simple SRoA algorithm with the Mem2Reg algorithm because they
// often interact, especially for C++ programs. As such, iterating between
// SRoA, then Mem2Reg until we run out of things to promote works well.
//
#define DEBUG_TYPE "scalarrepl"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Constants.h"
+#include "llvm/DIBuilder.h"
+#include "llvm/DebugInfo.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Function.h"
#include "llvm/GlobalVariable.h"
+#include "llvm/IRBuilder.h"
#include "llvm/Instructions.h"
#include "llvm/IntrinsicInst.h"
#include "llvm/LLVMContext.h"
#include "llvm/Module.h"
+#include "llvm/Operator.h"
#include "llvm/Pass.h"
-#include "llvm/Analysis/DebugInfo.h"
-#include "llvm/Analysis/DIBuilder.h"
+#include "llvm/ADT/SetVector.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/Statistic.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"
+#include "llvm/DataLayout.h"
+#include "llvm/Transforms/Utils/Local.h"
+#include "llvm/Transforms/Utils/PromoteMemToReg.h"
+#include "llvm/Transforms/Utils/SSAUpdater.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 {
- SROA(int T, bool hasDT, char &ID)
+ SROA(int T, bool hasDT, char &ID, int ST, int AT, int SLT)
: FunctionPass(ID), HasDomTree(hasDT) {
if (T == -1)
SRThreshold = 128;
else
SRThreshold = T;
+ if (ST == -1)
+ StructMemberThreshold = 32;
+ else
+ StructMemberThreshold = ST;
+ if (AT == -1)
+ ArrayElementThreshold = 8;
+ else
+ ArrayElementThreshold = AT;
+ if (SLT == -1)
+ // Do not limit the scalar integer load size if no threshold is given.
+ ScalarLoadThreshold = -1;
+ else
+ ScalarLoadThreshold = SLT;
}
bool runOnFunction(Function &F);
private:
bool HasDomTree;
- TargetData *TD;
+ DataLayout *TD;
/// DeadInsts - Keep track of instructions we have made dead, so that
/// we can remove them after we are done working.
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;
/// 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) {}
};
+ /// SRThreshold - The maximum alloca size to considered for SROA.
unsigned SRThreshold;
+ /// StructMemberThreshold - The maximum number of members a struct can
+ /// contain to be considered for SROA.
+ unsigned StructMemberThreshold;
+
+ /// ArrayElementThreshold - The maximum number of elements an array can
+ /// have to be considered for SROA.
+ unsigned ArrayElementThreshold;
+
+ /// ScalarLoadThreshold - The maximum size in bits of scalars to load when
+ /// converting to scalar
+ unsigned ScalarLoadThreshold;
+
void MarkUnsafe(AllocaInfo &I, Instruction *User) {
I.isUnsafe = true;
DEBUG(dbgs() << " Transformation preventing inst: " << *User << '\n');
SmallVector<AllocaInst*, 32> &NewElts);
void RewriteLoadUserOfWholeAlloca(LoadInst *LI, AllocaInst *AI,
SmallVector<AllocaInst*, 32> &NewElts);
-
- static MemTransferInst *isOnlyCopiedFromConstantGlobal(
- AllocaInst *AI, SmallVector<Instruction*, 4> &ToDelete);
+ bool ShouldAttemptScalarRepl(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) {
+ SROA_DT(int T = -1, int ST = -1, int AT = -1, int SLT = -1) :
+ SROA(T, true, ID, ST, AT, SLT) {
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.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) {
+ SROA_SSAUp(int T = -1, int ST = -1, int AT = -1, int SLT = -1) :
+ SROA(T, false, ID, ST, AT, SLT) {
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_DT::ID = 0;
// Public interface to the ScalarReplAggregates pass
FunctionPass *llvm::createScalarReplAggregatesPass(int Threshold,
- bool UseDomTree) {
+ bool UseDomTree,
+ int StructMemberThreshold,
+ int ArrayElementThreshold,
+ int ScalarLoadThreshold) {
if (UseDomTree)
- return new SROA_DT(Threshold);
- return new SROA_SSAUp(Threshold);
+ return new SROA_DT(Threshold, StructMemberThreshold, ArrayElementThreshold,
+ ScalarLoadThreshold);
+ return new SROA_SSAUp(Threshold, StructMemberThreshold,
+ ArrayElementThreshold, ScalarLoadThreshold);
}
class ConvertToScalarInfo {
/// AllocaSize - The size of the alloca being considered in bytes.
unsigned AllocaSize;
- const TargetData &TD;
+ const DataLayout &TD;
+ unsigned ScalarLoadThreshold;
/// IsNotTrivial - This is set to true if there is some access to the object
/// which means that mem2reg can't promote it.
/// isn't possible to turn into a vector type, it gets set to VoidTy.
VectorType *VectorTy;
- /// HadNonMemTransferAccess - True if there is at least one access to the
+ /// 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;
+ /// HadDynamicAccess - True if some element of this alloca was dynamic.
+ /// We don't yet have support for turning a dynamic access into a large
+ /// integer.
+ bool HadDynamicAccess;
+
public:
- explicit ConvertToScalarInfo(unsigned Size, const TargetData &td)
- : AllocaSize(Size), TD(td), IsNotTrivial(false), ScalarKind(Unknown),
- VectorTy(0), HadNonMemTransferAccess(false) { }
+ explicit ConvertToScalarInfo(unsigned Size, const DataLayout &td,
+ unsigned SLT)
+ : AllocaSize(Size), TD(td), ScalarLoadThreshold(SLT), IsNotTrivial(false),
+ ScalarKind(Unknown), VectorTy(0), HadNonMemTransferAccess(false),
+ HadDynamicAccess(false) { }
AllocaInst *TryConvert(AllocaInst *AI);
private:
- bool CanConvertToScalar(Value *V, uint64_t Offset);
+ bool CanConvertToScalar(Value *V, uint64_t Offset, Value* NonConstantIdx);
void MergeInTypeForLoadOrStore(Type *In, uint64_t Offset);
bool MergeInVectorType(VectorType *VInTy, uint64_t Offset);
- void ConvertUsesToScalar(Value *Ptr, AllocaInst *NewAI, uint64_t Offset);
+ void ConvertUsesToScalar(Value *Ptr, AllocaInst *NewAI, uint64_t Offset,
+ Value *NonConstantIdx);
Value *ConvertScalar_ExtractValue(Value *NV, Type *ToType,
- uint64_t Offset, IRBuilder<> &Builder);
+ uint64_t Offset, Value* NonConstantIdx,
+ IRBuilder<> &Builder);
Value *ConvertScalar_InsertValue(Value *StoredVal, Value *ExistingVal,
- uint64_t Offset, IRBuilder<> &Builder);
+ uint64_t Offset, Value* NonConstantIdx,
+ IRBuilder<> &Builder);
};
} // end anonymous namespace.
AllocaInst *ConvertToScalarInfo::TryConvert(AllocaInst *AI) {
// If we can't convert this scalar, or if mem2reg can trivially do it, bail
// out.
- if (!CanConvertToScalar(AI, 0) || !IsNotTrivial)
+ if (!CanConvertToScalar(AI, 0, 0) || !IsNotTrivial)
return 0;
// If an alloca has only memset / memcpy uses, it may still have an Unknown
NewTy = VectorTy; // Use the vector type.
} else {
unsigned BitWidth = AllocaSize * 8;
+
+ // Do not convert to scalar integer if the alloca size exceeds the
+ // scalar load threshold.
+ if (BitWidth > ScalarLoadThreshold)
+ return 0;
+
if ((ScalarKind == ImplicitVector || ScalarKind == Integer) &&
!HadNonMemTransferAccess && !TD.fitsInLegalInteger(BitWidth))
return 0;
+ // Dynamic accesses on integers aren't yet supported. They need us to shift
+ // by a dynamic amount which could be difficult to work out as we might not
+ // know whether to use a left or right shift.
+ if (ScalarKind == Integer && HadDynamicAccess)
+ return 0;
DEBUG(dbgs() << "CONVERT TO SCALAR INTEGER: " << *AI << "\n");
// Create and insert the integer alloca.
NewTy = IntegerType::get(AI->getContext(), BitWidth);
}
AllocaInst *NewAI = new AllocaInst(NewTy, 0, "", AI->getParent()->begin());
- ConvertUsesToScalar(AI, NewAI, 0);
+ ConvertUsesToScalar(AI, NewAI, 0, 0);
return NewAI;
}
///
/// 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) {
+bool ConvertToScalarInfo::CanConvertToScalar(Value *V, uint64_t Offset,
+ Value* NonConstantIdx) {
for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI!=E; ++UI) {
Instruction *User = cast<Instruction>(*UI);
if (BitCastInst *BCI = dyn_cast<BitCastInst>(User)) {
if (!onlyUsedByLifetimeMarkers(BCI))
IsNotTrivial = true; // Can't be mem2reg'd.
- if (!CanConvertToScalar(BCI, Offset))
+ if (!CanConvertToScalar(BCI, Offset, NonConstantIdx))
return false;
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())
+ PointerType* PtrTy = dyn_cast<PointerType>(GEP->getPointerOperandType());
+ if (!PtrTy)
return false;
// Compute the offset that this GEP adds to the pointer.
SmallVector<Value*, 8> Indices(GEP->op_begin()+1, GEP->op_end());
- if (!GEP->getPointerOperandType()->isPointerTy())
- return false;
- uint64_t GEPOffset = TD.getIndexedOffset(GEP->getPointerOperandType(),
+ Value *GEPNonConstantIdx = 0;
+ if (!GEP->hasAllConstantIndices()) {
+ if (!isa<VectorType>(PtrTy->getElementType()))
+ return false;
+ if (NonConstantIdx)
+ return false;
+ GEPNonConstantIdx = Indices.pop_back_val();
+ if (!GEPNonConstantIdx->getType()->isIntegerTy(32))
+ return false;
+ HadDynamicAccess = true;
+ } else
+ GEPNonConstantIdx = NonConstantIdx;
+ uint64_t GEPOffset = TD.getIndexedOffset(PtrTy,
Indices);
// See if all uses can be converted.
- if (!CanConvertToScalar(GEP, Offset+GEPOffset))
+ if (!CanConvertToScalar(GEP, Offset+GEPOffset, GEPNonConstantIdx))
return false;
IsNotTrivial = true; // Can't be mem2reg'd.
HadNonMemTransferAccess = true;
// 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 to dynamic index.
+ if (NonConstantIdx)
+ return false;
// Store of constant value.
if (!isa<ConstantInt>(MSI->getValue()))
return false;
// 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)) {
+ // Store to dynamic index.
+ if (NonConstantIdx)
+ return false;
ConstantInt *Len = dyn_cast<ConstantInt>(MTI->getLength());
if (Len == 0 || Len->getZExtValue() != AllocaSize || Offset != 0)
return false;
/// 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) {
+ uint64_t Offset,
+ Value* NonConstantIdx) {
while (!Ptr->use_empty()) {
Instruction *User = cast<Instruction>(Ptr->use_back());
if (BitCastInst *CI = dyn_cast<BitCastInst>(User)) {
- ConvertUsesToScalar(CI, NewAI, Offset);
+ ConvertUsesToScalar(CI, NewAI, Offset, NonConstantIdx);
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());
+ Value* GEPNonConstantIdx = 0;
+ if (!GEP->hasAllConstantIndices()) {
+ assert(!NonConstantIdx &&
+ "Dynamic GEP reading from dynamic GEP unsupported");
+ GEPNonConstantIdx = Indices.pop_back_val();
+ } else
+ GEPNonConstantIdx = NonConstantIdx;
uint64_t GEPOffset = TD.getIndexedOffset(GEP->getPointerOperandType(),
Indices);
- ConvertUsesToScalar(GEP, NewAI, Offset+GEPOffset*8);
+ ConvertUsesToScalar(GEP, NewAI, Offset+GEPOffset*8, GEPNonConstantIdx);
GEP->eraseFromParent();
continue;
}
// The load is a bit extract from NewAI shifted right by Offset bits.
Value *LoadedVal = Builder.CreateLoad(NewAI);
Value *NewLoadVal
- = ConvertScalar_ExtractValue(LoadedVal, LI->getType(), Offset, Builder);
+ = ConvertScalar_ExtractValue(LoadedVal, LI->getType(), Offset,
+ NonConstantIdx, Builder);
LI->replaceAllUsesWith(NewLoadVal);
LI->eraseFromParent();
continue;
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);
+ NonConstantIdx, Builder);
Builder.CreateStore(New, NewAI);
SI->eraseFromParent();
// transform it into a store of the expanded constant value.
if (MemSetInst *MSI = dyn_cast<MemSetInst>(User)) {
assert(MSI->getRawDest() == Ptr && "Consistency error!");
+ assert(!NonConstantIdx && "Cannot replace dynamic memset with insert");
int64_t SNumBytes = cast<ConstantInt>(MSI->getLength())->getSExtValue();
if (SNumBytes > 0 && (SNumBytes >> 32) == 0) {
unsigned NumBytes = static_cast<unsigned>(SNumBytes);
Instruction *Old = Builder.CreateLoad(NewAI, NewAI->getName()+".in");
Value *New = ConvertScalar_InsertValue(
ConstantInt::get(User->getContext(), APVal),
- Old, Offset, Builder);
+ Old, Offset, 0, Builder);
Builder.CreateStore(New, NewAI);
// If the load we just inserted is now dead, then the memset overwrote
// 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");
+ assert(!NonConstantIdx && "Cannot replace dynamic transfer with insert");
// 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
/// shifted to the right.
Value *ConvertToScalarInfo::
ConvertScalar_ExtractValue(Value *FromVal, Type *ToType,
- uint64_t Offset, IRBuilder<> &Builder) {
+ uint64_t Offset, Value* NonConstantIdx,
+ IRBuilder<> &Builder) {
// If the load is of the whole new alloca, no conversion is needed.
Type *FromType = FromVal->getType();
if (FromType == ToType && Offset == 0)
assert(EltSize*Elt == Offset && "Invalid modulus in validity checking");
}
// Return the element extracted out of it.
- Value *V = Builder.CreateExtractElement(FromVal, Builder.getInt32(Elt));
+ Value *Idx;
+ if (NonConstantIdx) {
+ if (Elt)
+ Idx = Builder.CreateAdd(NonConstantIdx,
+ Builder.getInt32(Elt),
+ "dyn.offset");
+ else
+ Idx = NonConstantIdx;
+ } else
+ Idx = Builder.getInt32(Elt);
+ Value *V = Builder.CreateExtractElement(FromVal, Idx);
if (V->getType() != ToType)
V = Builder.CreateBitCast(V, ToType);
return V;
// If ToType is a first class aggregate, extract out each of the pieces and
// use insertvalue's to form the FCA.
if (StructType *ST = dyn_cast<StructType>(ToType)) {
+ assert(!NonConstantIdx &&
+ "Dynamic indexing into struct types not supported");
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);
+ 0, Builder);
Res = Builder.CreateInsertValue(Res, Elt, i);
}
return Res;
}
if (ArrayType *AT = dyn_cast<ArrayType>(ToType)) {
+ assert(!NonConstantIdx &&
+ "Dynamic indexing into array types not supported");
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);
+ Offset+i*EltSize, 0, Builder);
Res = Builder.CreateInsertValue(Res, Elt, i);
}
return Res;
///
/// Offset is an offset from the original alloca, in bits that need to be
/// shifted to the right.
+///
+/// NonConstantIdx is an index value if there was a GEP with a non-constant
+/// index value. If this is 0 then all GEPs used to find this insert address
+/// are constant.
Value *ConvertToScalarInfo::
ConvertScalar_InsertValue(Value *SV, Value *Old,
- uint64_t Offset, IRBuilder<> &Builder) {
+ uint64_t Offset, Value* NonConstantIdx,
+ IRBuilder<> &Builder) {
// Convert the stored type to the actual type, shift it left to insert
// then 'or' into place.
Type *AllocaType = Old->getType();
SV = Builder.CreateBitCast(SV, EltTy);
uint64_t EltSize = TD.getTypeAllocSizeInBits(EltTy);
unsigned Elt = Offset/EltSize;
- return Builder.CreateInsertElement(Old, SV, Builder.getInt32(Elt));
+ Value *Idx;
+ if (NonConstantIdx) {
+ if (Elt)
+ Idx = Builder.CreateAdd(NonConstantIdx,
+ Builder.getInt32(Elt),
+ "dyn.offset");
+ else
+ Idx = NonConstantIdx;
+ } else
+ Idx = Builder.getInt32(Elt);
+ return Builder.CreateInsertElement(Old, SV, Idx);
}
// If SV is a first-class aggregate value, insert each value recursively.
if (StructType *ST = dyn_cast<StructType>(SV->getType())) {
+ assert(!NonConstantIdx &&
+ "Dynamic indexing into struct types not supported");
const StructLayout &Layout = *TD.getStructLayout(ST);
for (unsigned i = 0, e = ST->getNumElements(); i != e; ++i) {
Value *Elt = Builder.CreateExtractValue(SV, i);
Old = ConvertScalar_InsertValue(Elt, Old,
Offset+Layout.getElementOffsetInBits(i),
- Builder);
+ 0, Builder);
}
return Old;
}
if (ArrayType *AT = dyn_cast<ArrayType>(SV->getType())) {
+ assert(!NonConstantIdx &&
+ "Dynamic indexing into array types not supported");
uint64_t EltSize = TD.getTypeAllocSizeInBits(AT->getElementType());
for (unsigned i = 0, e = AT->getNumElements(); i != e; ++i) {
Value *Elt = Builder.CreateExtractValue(SV, i);
- Old = ConvertScalar_InsertValue(Elt, Old, Offset+i*EltSize, Builder);
+ Old = ConvertScalar_InsertValue(Elt, Old, Offset+i*EltSize, 0, Builder);
}
return Old;
}
if (SV->getType()->isFloatingPointTy() || SV->getType()->isVectorTy())
SV = Builder.CreateBitCast(SV, IntegerType::get(SV->getContext(),SrcWidth));
else if (SV->getType()->isPointerTy())
- SV = Builder.CreatePtrToInt(SV, TD.getIntPtrType(SV->getContext()));
+ SV = Builder.CreatePtrToInt(SV, TD.getIntPtrType(SV->getType()));
// Zero extend or truncate the value if needed.
if (SV->getType() != AllocaType) {
bool SROA::runOnFunction(Function &F) {
- TD = getAnalysisIfAvailable<TargetData>();
+ TD = getAnalysisIfAvailable<DataLayout>();
bool Changed = performPromotion(F);
- // FIXME: ScalarRepl currently depends on TargetData more than it
+ // FIXME: ScalarRepl currently depends on DataLayout more than it
// theoretically needs to. It should be refactored in order to support
// target-independent IR. Until this is done, just skip the actual
// scalar-replacement portion of this pass.
AllocaPromoter(const SmallVectorImpl<Instruction*> &Insts, SSAUpdater &S,
DIBuilder *DB)
: LoadAndStorePromoter(Insts, S), AI(0), DIB(DB) {}
-
+
void run(AllocaInst *AI, const SmallVectorImpl<Instruction*> &Insts) {
// Remember which alloca we're promoting (for isInstInList).
this->AI = AI;
LoadAndStorePromoter::run(Insts);
AI->eraseFromParent();
- for (SmallVector<DbgDeclareInst *, 4>::iterator I = DDIs.begin(),
+ for (SmallVector<DbgDeclareInst *, 4>::iterator I = DDIs.begin(),
E = DDIs.end(); I != E; ++I) {
DbgDeclareInst *DDI = *I;
DDI->eraseFromParent();
}
- for (SmallVector<DbgValueInst *, 4>::iterator I = DVIs.begin(),
+ for (SmallVector<DbgValueInst *, 4>::iterator I = DVIs.begin(),
E = DVIs.end(); I != E; ++I) {
DbgValueInst *DVI = *I;
DVI->eraseFromParent();
}
}
-
+
virtual bool isInstInList(Instruction *I,
const SmallVectorImpl<Instruction*> &Insts) const {
if (LoadInst *LI = dyn_cast<LoadInst>(I))
}
virtual void updateDebugInfo(Instruction *Inst) const {
- for (SmallVector<DbgDeclareInst *, 4>::const_iterator I = DDIs.begin(),
+ for (SmallVector<DbgDeclareInst *, 4>::const_iterator I = DDIs.begin(),
E = DDIs.end(); I != E; ++I) {
DbgDeclareInst *DDI = *I;
if (StoreInst *SI = dyn_cast<StoreInst>(Inst))
else if (LoadInst *LI = dyn_cast<LoadInst>(Inst))
ConvertDebugDeclareToDebugValue(DDI, LI, *DIB);
}
- for (SmallVector<DbgValueInst *, 4>::const_iterator I = DVIs.begin(),
+ for (SmallVector<DbgValueInst *, 4>::const_iterator I = DVIs.begin(),
E = DVIs.end(); I != E; ++I) {
DbgValueInst *DVI = *I;
Value *Arg = NULL;
///
/// 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) {
+static bool isSafeSelectToSpeculate(SelectInst *SI, const DataLayout *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->isSimple()) 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;
}
-
+
return true;
}
///
/// 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) {
+static bool isSafePHIToSpeculate(PHINode *PN, const DataLayout *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.
UI != UE; ++UI) {
LoadInst *LI = dyn_cast<LoadInst>(*UI);
if (LI == 0 || !LI->isSimple()) 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
if (InVal->isDereferenceablePointer() ||
isSafeToLoadUnconditionally(InVal, Pred->getTerminator(), MaxAlign, TD))
continue;
-
+
return false;
}
-
+
return true;
}
/// 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) {
+static bool tryToMakeAllocaBePromotable(AllocaInst *AI, const DataLayout *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;
return false;
continue;
}
-
+
if (StoreInst *SI = dyn_cast<StoreInst>(U)) {
if (SI->getOperand(0) == AI || !SI->isSimple())
return false; // Don't allow a store OF the AI, only INTO the AI.
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);
// 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;
}
-
+
if (BitCastInst *BCI = dyn_cast<BitCastInst>(U)) {
if (onlyUsedByLifetimeMarkers(BCI)) {
InstsToRewrite.insert(BCI);
continue;
}
}
-
+
return false;
}
// 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) {
// loads with a new select.
while (!SI->use_empty()) {
LoadInst *LI = cast<LoadInst>(SI->use_back());
-
+
IRBuilder<> Builder(LI);
- LoadInst *TrueLoad =
+ LoadInst *TrueLoad =
Builder.CreateLoad(SI->getTrueValue(), LI->getName()+".t");
- LoadInst *FalseLoad =
+ LoadInst *FalseLoad =
Builder.CreateLoad(SI->getFalseValue(), LI->getName()+".f");
-
+
// Transfer alignment and TBAA info if present.
TrueLoad->setAlignment(LI->getAlignment());
FalseLoad->setAlignment(LI->getAlignment());
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]);
PN->eraseFromParent();
continue;
}
-
+
Type *LoadTy = cast<PointerType>(PN->getType())->getElementType();
PHINode *NewPN = PHINode::Create(LoadTy, PN->getNumIncomingValues(),
PN->getName()+".ld", PN);
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];
Load->setAlignment(Align);
if (TBAATag) Load->setMetadata(LLVMContext::MD_tbaa, TBAATag);
}
-
+
NewPN->addIncoming(Load, Pred);
}
-
+
PN->eraseFromParent();
}
-
+
++NumAdjusted;
return true;
}
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)
/// 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) {
+bool SROA::ShouldAttemptScalarRepl(AllocaInst *AI) {
Type *T = AI->getAllocatedType();
- // Do not promote any struct into more than 32 separate vars.
+ // Do not promote any struct that has too many members.
if (StructType *ST = dyn_cast<StructType>(T))
- return ST->getNumElements() <= 32;
- // Arrays are much less likely to be safe for SROA; only consider
- // them if they are very small.
+ return ST->getNumElements() <= StructMemberThreshold;
+ // Do not promote any array that has too many elements.
if (ArrayType *AT = dyn_cast<ArrayType>(T))
- return AT->getNumElements() <= 8;
+ return AT->getNumElements() <= ArrayElementThreshold;
return false;
}
-
// performScalarRepl - This algorithm is a simple worklist driven algorithm,
// which runs on all of the alloca instructions in the function, removing them
// if they are only used by getelementptr instructions.
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
- // constructs like "void foo() { int A[] = {1,2,3,4,5,6,7,8,9...}; }" if 'A'
- // is only subsequently read.
- SmallVector<Instruction *, 4> ToDelete;
- if (MemTransferInst *Copy = isOnlyCopiedFromConstantGlobal(AI, ToDelete)) {
- DEBUG(dbgs() << "Found alloca equal to global: " << *AI << '\n');
- DEBUG(dbgs() << " memcpy = " << *Copy << '\n');
- for (unsigned i = 0, e = ToDelete.size(); i != e; ++i)
- ToDelete[i]->eraseFromParent();
- Constant *TheSrc = cast<Constant>(Copy->getSource());
- AI->replaceAllUsesWith(ConstantExpr::getBitCast(TheSrc, AI->getType()));
- Copy->eraseFromParent(); // Don't mutate the global.
- AI->eraseFromParent();
- ++NumGlobals;
- 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
// promoted itself. If so, we don't want to transform it needlessly. Note
// that we can't just check based on the type: the alloca may be of an i32
// but that has pointer arithmetic to set byte 3 of it or something.
- if (AllocaInst *NewAI =
- ConvertToScalarInfo((unsigned)AllocaSize, *TD).TryConvert(AI)) {
+ if (AllocaInst *NewAI = ConvertToScalarInfo(
+ (unsigned)AllocaSize, *TD, ScalarLoadThreshold).TryConvert(AI)) {
NewAI->takeName(AI);
AI->eraseFromParent();
++NumConverted;
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->isSimple() || SI->getOperand(0) == I)
return MarkUnsafe(Info, User);
-
+
Type *SIType = SI->getOperand(0)->getType();
isSafeMemAccess(Offset, TD->getTypeAllocSize(SIType),
SIType, true, Info, SI, true /*AllowWholeAccess*/);
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.
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)) {
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->isSimple() || SI->getOperand(0) == I)
return MarkUnsafe(Info, User);
-
+
Type *SIType = SI->getOperand(0)->getType();
isSafeMemAccess(Offset, TD->getTypeAllocSize(SIType),
SIType, true, Info, SI, false /*AllowWholeAccess*/);
gep_type_iterator GEPIt = gep_type_begin(GEPI), E = gep_type_end(GEPI);
if (GEPIt == E)
return;
+ bool NonConstant = false;
+ unsigned NonConstantIdxSize = 0;
// Walk through the GEP type indices, checking the types that this indexes
// into.
continue;
ConstantInt *IdxVal = dyn_cast<ConstantInt>(GEPIt.getOperand());
- if (!IdxVal)
- return MarkUnsafe(Info, GEPI);
+ if (!IdxVal) {
+ // Non constant GEPs are only a problem on arrays, structs, and pointers
+ // Vectors can be dynamically indexed.
+ // FIXME: Add support for dynamic indexing on arrays. This should be
+ // ok on any subarrays of the alloca array, eg, a[0][i] is ok, but a[i][0]
+ // isn't.
+ if (!(*GEPIt)->isVectorTy())
+ return MarkUnsafe(Info, GEPI);
+ NonConstant = true;
+ NonConstantIdxSize = TD->getTypeAllocSize(*GEPIt);
+ }
}
// Compute the offset due to this GEP and check if the alloca has a
// component element at that offset.
SmallVector<Value*, 8> Indices(GEPI->op_begin() + 1, GEPI->op_end());
+ // If this GEP is non constant then the last operand must have been a
+ // dynamic index into a vector. Pop this now as it has no impact on the
+ // constant part of the offset.
+ if (NonConstant)
+ Indices.pop_back();
Offset += TD->getIndexedOffset(GEPI->getPointerOperandType(), Indices);
- if (!TypeHasComponent(Info.AI->getAllocatedType(), Offset, 0))
+ if (!TypeHasComponent(Info.AI->getAllocatedType(), Offset,
+ NonConstantIdxSize))
MarkUnsafe(Info, GEPI);
}
if (Offset >= AT->getNumElements() * EltSize)
return false;
Offset %= EltSize;
+ } else if (VectorType *VT = dyn_cast<VectorType>(T)) {
+ EltTy = VT->getElementType();
+ EltSize = TD->getTypeAllocSize(EltTy);
+ if (Offset >= VT->getNumElements() * EltSize)
+ return false;
+ Offset %= EltSize;
} else {
return false;
}
RewriteBitCast(BC, AI, Offset, NewElts);
continue;
}
-
+
if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(User)) {
RewriteGEP(GEPI, AI, Offset, NewElts);
continue;
}
-
+
if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(User)) {
ConstantInt *Length = dyn_cast<ConstantInt>(MI->getLength());
uint64_t MemSize = Length->getZExtValue();
}
continue;
}
-
+
if (LoadInst *LI = dyn_cast<LoadInst>(User)) {
Type *LIType = LI->getType();
-
+
if (isCompatibleAggregate(LIType, AI->getAllocatedType())) {
// Replace:
// %res = load { i32, i32 }* %alloc
}
continue;
}
-
+
if (StoreInst *SI = dyn_cast<StoreInst>(User)) {
Value *Val = SI->getOperand(0);
Type *SIType = Val->getType();
}
continue;
}
-
+
if (isa<SelectInst>(User) || isa<PHINode>(User)) {
- // If we have a PHI user of the alloca itself (as opposed to a GEP or
+ // 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.
Offset -= Layout->getElementOffset(Idx);
IdxTy = Type::getInt32Ty(T->getContext());
return Idx;
+ } else if (ArrayType *AT = dyn_cast<ArrayType>(T)) {
+ T = AT->getElementType();
+ uint64_t EltSize = TD->getTypeAllocSize(T);
+ Idx = Offset / EltSize;
+ Offset -= Idx * EltSize;
+ IdxTy = Type::getInt64Ty(T->getContext());
+ return Idx;
}
- ArrayType *AT = cast<ArrayType>(T);
- T = AT->getElementType();
+ VectorType *VT = cast<VectorType>(T);
+ T = VT->getElementType();
uint64_t EltSize = TD->getTypeAllocSize(T);
Idx = Offset / EltSize;
Offset -= Idx * EltSize;
SmallVector<AllocaInst*, 32> &NewElts) {
uint64_t OldOffset = Offset;
SmallVector<Value*, 8> Indices(GEPI->op_begin() + 1, GEPI->op_end());
+ // If the GEP was dynamic then it must have been a dynamic vector lookup.
+ // In this case, it must be the last GEP operand which is dynamic so keep that
+ // aside until we've found the constant GEP offset then add it back in at the
+ // end.
+ Value* NonConstantIdx = 0;
+ if (!GEPI->hasAllConstantIndices())
+ NonConstantIdx = Indices.pop_back_val();
Offset += TD->getIndexedOffset(GEPI->getPointerOperandType(), Indices);
RewriteForScalarRepl(GEPI, AI, Offset, NewElts);
uint64_t EltIdx = FindElementAndOffset(T, EltOffset, IdxTy);
NewArgs.push_back(ConstantInt::get(IdxTy, EltIdx));
}
+ if (NonConstantIdx) {
+ Type* GepTy = T;
+ // This GEP has a dynamic index. We need to add "i32 0" to index through
+ // any structs or arrays in the original type until we get to the vector
+ // to index.
+ while (!isa<VectorType>(GepTy)) {
+ NewArgs.push_back(Constant::getNullValue(i32Ty));
+ GepTy = cast<CompositeType>(GepTy)->getTypeAtIndex(0U);
+ }
+ NewArgs.push_back(NonConstantIdx);
+ }
Instruction *Val = NewElts[Idx];
if (NewArgs.size() > 1) {
Val = GetElementPtrInst::CreateInBounds(Val, NewArgs, "", GEPI);
uint64_t AllocaSizeBits = TD->getTypeAllocSizeInBits(AllocaEltTy);
IRBuilder<> Builder(SI);
-
+
// Handle tail padding by extending the operand
if (TD->getTypeSizeInBits(SrcVal->getType()) != AllocaSizeBits)
SrcVal = Builder.CreateZExt(SrcVal,
/// HasPadding - Return true if the specified type has any structure or
/// alignment padding in between the elements that would be split apart
/// by SROA; return false otherwise.
-static bool HasPadding(Type *Ty, const TargetData &TD) {
+static bool HasPadding(Type *Ty, const DataLayout &TD) {
if (ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
Ty = ATy->getElementType();
return TD.getTypeSizeInBits(Ty) != TD.getTypeAllocSizeInBits(Ty);
return false;
}
}
-
- return true;
-}
-
-
-/// PointsToConstantGlobal - Return true if V (possibly indirectly) points to
-/// some part of a constant global variable. This intentionally only accepts
-/// constant expressions because we don't can't rewrite arbitrary instructions.
-static bool PointsToConstantGlobal(Value *V) {
- if (GlobalVariable *GV = dyn_cast<GlobalVariable>(V))
- return GV->isConstant();
- if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
- if (CE->getOpcode() == Instruction::BitCast ||
- CE->getOpcode() == Instruction::GetElementPtr)
- return PointsToConstantGlobal(CE->getOperand(0));
- return false;
-}
-
-/// isOnlyCopiedFromConstantGlobal - Recursively walk the uses of a (derived)
-/// pointer to an alloca. Ignore any reads of the pointer, return false if we
-/// 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
-/// can optimize this.
-static bool
-isOnlyCopiedFromConstantGlobal(Value *V, MemTransferInst *&TheCopy,
- bool isOffset,
- SmallVector<Instruction *, 4> &LifetimeMarkers) {
- // We track lifetime intrinsics as we encounter them. If we decide to go
- // ahead and replace the value with the global, this lets the caller quickly
- // eliminate the markers.
-
- 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)) {
- // Ignore non-volatile loads, they are always ok.
- if (!LI->isSimple()) 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,
- LifetimeMarkers))
- return false;
- continue;
- }
- if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(U)) {
- // If the GEP has all zero indices, it doesn't offset the pointer. If it
- // doesn't, it does.
- if (!isOnlyCopiedFromConstantGlobal(GEP, TheCopy,
- isOffset || !GEP->hasAllZeroIndices(),
- LifetimeMarkers))
- return false;
- continue;
- }
-
- if (CallSite CS = U) {
- // 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 a readonly/readnone call site, then we know it is just a
- // load (but one that potentially returns the value itself), so we can
- // ignore it if we know that the value isn't captured.
- unsigned ArgNo = CS.getArgumentNo(UI);
- if (CS.onlyReadsMemory() &&
- (CS.getInstruction()->use_empty() || CS.doesNotCapture(ArgNo)))
- 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.
- if (CS.isByValArgument(ArgNo))
- continue;
- }
-
- // Lifetime intrinsics can be handled by the caller.
- if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(U)) {
- if (II->getIntrinsicID() == Intrinsic::lifetime_start ||
- II->getIntrinsicID() == Intrinsic::lifetime_end) {
- assert(II->use_empty() && "Lifetime markers have no result to use!");
- LifetimeMarkers.push_back(II);
- 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;
- }
return true;
}
-
-/// isOnlyCopiedFromConstantGlobal - Return true if the specified alloca is only
-/// modified by a copy from a constant global. If we can prove this, we can
-/// replace any uses of the alloca with uses of the global directly.
-MemTransferInst *
-SROA::isOnlyCopiedFromConstantGlobal(AllocaInst *AI,
- SmallVector<Instruction*, 4> &ToDelete) {
- MemTransferInst *TheCopy = 0;
- if (::isOnlyCopiedFromConstantGlobal(AI, TheCopy, false, ToDelete))
- return TheCopy;
- return 0;
-}
projects / oota-llvm.git / blobdiff