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;
}
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@63596 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/ScalarReplAggregates.cpp b/lib/Transforms/Scalar/ScalarReplAggregates.cpp
index 5031619..83572d6 100644
--- a/lib/Transforms/Scalar/ScalarReplAggregates.cpp
+++ b/lib/Transforms/Scalar/ScalarReplAggregates.cpp
@@ -130,8 +130,8 @@
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 @@
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 @@
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 @@
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 @@
///
/// 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 @@
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 @@
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 @@
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;
}