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Teach ConvertUsesToScalar to handle memset, allowing it to handle 

crazy cases like:

struct f {  int A, B, C, D, E, F; };
short test4() {
  struct f A;
  A.A = 1;
  memset(&A.B, 2, 12);
  return A.C;
}

llvm-svn: 63596
This commit is contained in:
Chris Lattner 2009-02-03 02:01:43 +00:00
parent db39362c90
commit 6aa6b1f263
2 changed files with 73 additions and 21 deletions
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76
llvm/lib/Transforms/Scalar/ScalarReplAggregates.cpp
View File

@ -130,8 +130,8 @@ namespace {
void ConvertUsesToScalar(Value *Ptr, AllocaInst *NewAI, uint64_t Offset);
Value *ConvertUsesOfLoadToScalar(LoadInst *LI, AllocaInst *NewAI,
uint64_t Offset);
Value *ConvertUsesOfStoreToScalar(StoreInst *SI, AllocaInst *NewAI,
uint64_t Offset);
Value *ConvertUsesOfStoreToScalar(Value *StoredVal, AllocaInst *NewAI,
uint64_t Offset, Instruction *InsertPt);
static Instruction *isOnlyCopiedFromConstantGlobal(AllocationInst *AI);
};
}
@ -1274,6 +1274,18 @@ bool SROA::CanConvertToScalar(Value *V, bool &IsNotTrivial,
continue;
}
// If this is a constant sized memset of a constant value (e.g. 0) we can
// handle it.
if (isa<MemSetInst>(User) &&
// Store of constant value.
isa<ConstantInt>(User->getOperand(2)) &&
// Store with constant size.
isa<ConstantInt>(User->getOperand(3))) {
VecTy = Type::VoidTy;
IsNotTrivial = true;
continue;
}
// Otherwise, we cannot handle this!
return false;
}
@ -1301,7 +1313,8 @@ void SROA::ConvertUsesToScalar(Value *Ptr, AllocaInst *NewAI, uint64_t Offset) {
if (StoreInst *SI = dyn_cast<StoreInst>(User)) {
assert(SI->getOperand(0) != Ptr && "Consistency error!");
new StoreInst(ConvertUsesOfStoreToScalar(SI, NewAI, Offset), NewAI, SI);
new StoreInst(ConvertUsesOfStoreToScalar(SI->getOperand(0), NewAI,
Offset, SI), NewAI, SI);
SI->eraseFromParent();
continue;
}
@ -1321,6 +1334,29 @@ void SROA::ConvertUsesToScalar(Value *Ptr, AllocaInst *NewAI, uint64_t Offset) {
GEP->eraseFromParent();
continue;
}
// If this is a constant sized memset of a constant value (e.g. 0) we can
// transform it into a store of the expanded constant value.
if (MemSetInst *MSI = dyn_cast<MemSetInst>(User)) {
assert(MSI->getRawDest() == Ptr && "Consistency error!");
unsigned NumBytes = cast<ConstantInt>(MSI->getLength())->getZExtValue();
unsigned Val = cast<ConstantInt>(MSI->getValue())->getZExtValue();
// Compute the value replicated the right number of times.
APInt APVal(NumBytes*8, Val);
// Splat the value if non-zero.
if (Val)
for (unsigned i = 1; i != NumBytes; ++i)
APVal |= APVal << 8;
new StoreInst(ConvertUsesOfStoreToScalar(ConstantInt::get(APVal), NewAI,
Offset, MSI), NewAI, MSI);
MSI->eraseFromParent();
continue;
}
assert(0 && "Unsupported operation!");
abort();
}
@ -1422,40 +1458,38 @@ Value *SROA::ConvertUsesOfLoadToScalar(LoadInst *LI, AllocaInst *NewAI,
///
/// 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.
Value *SROA::ConvertUsesOfStoreToScalar(StoreInst *SI, AllocaInst *NewAI,
uint64_t Offset) {
Value *SROA::ConvertUsesOfStoreToScalar(Value *SV, AllocaInst *NewAI,
uint64_t Offset, Instruction *IP) {
// Convert the stored type to the actual type, shift it left to insert
// then 'or' into place.
Value *SV = SI->getOperand(0);
const Type *AllocaType = NewAI->getType()->getElementType();
if (SV->getType() == AllocaType && Offset == 0) {
if (SV->getType() == AllocaType && Offset == 0)
return SV;
}
if (const VectorType *VTy = dyn_cast<VectorType>(AllocaType)) {
Value *Old = new LoadInst(NewAI, NewAI->getName()+".in", SI);
Value *Old = new LoadInst(NewAI, NewAI->getName()+".in", IP);
// If the result alloca is a vector type, this is either an element
// access or a bitcast to another vector type.
if (isa<VectorType>(SV->getType())) {
SV = new BitCastInst(SV, AllocaType, SV->getName(), SI);
SV = new BitCastInst(SV, AllocaType, SV->getName(), IP);
} else {
// Must be an element insertion.
unsigned Elt = Offset/TD->getTypePaddedSizeInBits(VTy->getElementType());
if (SV->getType() != VTy->getElementType())
SV = new BitCastInst(SV, VTy->getElementType(), "tmp", SI);
SV = new BitCastInst(SV, VTy->getElementType(), "tmp", IP);
SV = InsertElementInst::Create(Old, SV,
ConstantInt::get(Type::Int32Ty, Elt),
"tmp", SI);
"tmp", IP);
}
return SV;
}
Value *Old = new LoadInst(NewAI, NewAI->getName()+".in", SI);
Value *Old = new LoadInst(NewAI, NewAI->getName()+".in", IP);
// If SV is a float, convert it to the appropriate integer type.
// If it is a pointer, do the same, and also handle ptr->ptr casts
@ -1465,19 +1499,19 @@ Value *SROA::ConvertUsesOfStoreToScalar(StoreInst *SI, AllocaInst *NewAI,
unsigned SrcStoreWidth = TD->getTypeStoreSizeInBits(SV->getType());
unsigned DestStoreWidth = TD->getTypeStoreSizeInBits(AllocaType);
if (SV->getType()->isFloatingPoint() || isa<VectorType>(SV->getType()))
SV = new BitCastInst(SV, IntegerType::get(SrcWidth), SV->getName(), SI);
SV = new BitCastInst(SV, IntegerType::get(SrcWidth), SV->getName(), IP);
else if (isa<PointerType>(SV->getType()))
SV = new PtrToIntInst(SV, TD->getIntPtrType(), SV->getName(), SI);
SV = new PtrToIntInst(SV, TD->getIntPtrType(), SV->getName(), IP);
// Zero extend or truncate the value if needed.
if (SV->getType() != AllocaType) {
if (SV->getType()->getPrimitiveSizeInBits() <
AllocaType->getPrimitiveSizeInBits())
SV = new ZExtInst(SV, AllocaType, SV->getName(), SI);
SV = new ZExtInst(SV, AllocaType, SV->getName(), IP);
else {
// Truncation may be needed if storing more than the alloca can hold
// (undefined behavior).
SV = new TruncInst(SV, AllocaType, SV->getName(), SI);
SV = new TruncInst(SV, AllocaType, SV->getName(), IP);
SrcWidth = DestWidth;
SrcStoreWidth = DestStoreWidth;
}
@ -1502,12 +1536,12 @@ Value *SROA::ConvertUsesOfStoreToScalar(StoreInst *SI, AllocaInst *NewAI,
if (ShAmt > 0 && (unsigned)ShAmt < DestWidth) {
SV = BinaryOperator::CreateShl(SV,
ConstantInt::get(SV->getType(), ShAmt),
SV->getName(), SI);
SV->getName(), IP);
Mask <<= ShAmt;
} else if (ShAmt < 0 && (unsigned)-ShAmt < DestWidth) {
SV = BinaryOperator::CreateLShr(SV,
ConstantInt::get(SV->getType(), -ShAmt),
SV->getName(), SI);
SV->getName(), IP);
Mask = Mask.lshr(-ShAmt);
}
@ -1516,8 +1550,8 @@ Value *SROA::ConvertUsesOfStoreToScalar(StoreInst *SI, AllocaInst *NewAI,
if (SrcWidth != DestWidth) {
assert(DestWidth > SrcWidth);
Old = BinaryOperator::CreateAnd(Old, ConstantInt::get(~Mask),
Old->getName()+".mask", SI);
SV = BinaryOperator::CreateOr(Old, SV, SV->getName()+".ins", SI);
Old->getName()+".mask", IP);
SV = BinaryOperator::CreateOr(Old, SV, SV->getName()+".ins", IP);
}
return SV;
}

18
llvm/test/Transforms/ScalarRepl/memset-aggregate.ll
View File

@ -1,6 +1,7 @@
; PR1226
; RUN: llvm-as < %s | opt -scalarrepl | llvm-dis | grep {ret i32 16843009}
; RUN: llvm-as < %s | opt -scalarrepl | llvm-dis | not grep alloca
; RUN: llvm-as < %s | opt -scalarrepl -instcombine | llvm-dis | grep {ret i16 514}
target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64"
target triple = "i686-apple-darwin8"
@ -46,3 +47,20 @@ entry:
%tmp7 = load i32* %tmp6 ; <i32> [#uses=1]
ret i32 %tmp7
}
%struct.f = type { i32, i32, i32, i32, i32, i32 }
define i16 @test4() nounwind {
entry:
%A = alloca %struct.f, align 8 ; <%struct.f*> [#uses=3]
%0 = getelementptr %struct.f* %A, i32 0, i32 0 ; <i32*> [#uses=1]
store i32 1, i32* %0, align 8
%1 = getelementptr %struct.f* %A, i32 0, i32 1 ; <i32*> [#uses=1]
%2 = bitcast i32* %1 to i8* ; <i8*> [#uses=1]
call void @llvm.memset.i32(i8* %2, i8 2, i32 12, i32 4)
%3 = getelementptr %struct.f* %A, i32 0, i32 2 ; <i32*> [#uses=1]
%4 = load i32* %3, align 8 ; <i32> [#uses=1]
%retval12 = trunc i32 %4 to i16 ; <i16> [#uses=1]
ret i16 %retval12
}