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Implement Transforms/InstCombine/cast-load-gep.ll, which allows us to devirtualize

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11 indirect calls in perlbmk.

llvm-svn: 19947
This commit is contained in:
Chris Lattner 2005-01-31 04:50:46 +00:00
parent b7b94f8e9b
commit a4ba8e9f0d
1 changed files with 29 additions and 15 deletions
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44
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -4623,24 +4623,38 @@ static Constant *GetGEPGlobalInitializer(Constant *C, ConstantExpr *CE) {
static Instruction *InstCombineLoadCast(InstCombiner &IC, LoadInst &LI) {
User *CI = cast<User>(LI.getOperand(0));
Value *CastOp = CI->getOperand(0);
const Type *DestPTy = cast<PointerType>(CI->getType())->getElementType();
if (const PointerType *SrcTy =
dyn_cast<PointerType>(CI->getOperand(0)->getType())) {
if (const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType())) {
const Type *SrcPTy = SrcTy->getElementType();
if (SrcPTy->isSized() && DestPTy->isSized() &&
IC.getTargetData().getTypeSize(SrcPTy) ==
IC.getTargetData().getTypeSize(DestPTy) &&
(SrcPTy->isInteger() || isa<PointerType>(SrcPTy)) &&
(DestPTy->isInteger() || isa<PointerType>(DestPTy))) {
// Okay, we are casting from one integer or pointer type to another of
// the same size. Instead of casting the pointer before the load, cast
// the result of the loaded value.
Value *NewLoad = IC.InsertNewInstBefore(new LoadInst(CI->getOperand(0),
CI->getName(),
LI.isVolatile()),LI);
// Now cast the result of the load.
return new CastInst(NewLoad, LI.getType());
if (DestPTy->isInteger() || isa<PointerType>(DestPTy)) {
// If the source is an array, the code below will not succeed. Check to
// see if a trivial 'gep P, 0, 0' will help matters. Only do this for
// constants.
if (const ArrayType *ASrcTy = dyn_cast<ArrayType>(SrcPTy))
if (Constant *CSrc = dyn_cast<Constant>(CastOp))
if (ASrcTy->getNumElements() != 0) {
std::vector<Value*> Idxs(2, Constant::getNullValue(Type::IntTy));
CastOp = ConstantExpr::getGetElementPtr(CSrc, Idxs);
SrcTy = cast<PointerType>(CastOp->getType());
SrcPTy = SrcTy->getElementType();
}
if ((SrcPTy->isInteger() || isa<PointerType>(SrcPTy)) &&
IC.getTargetData().getTypeSize(SrcPTy) ==
IC.getTargetData().getTypeSize(DestPTy)) {
// Okay, we are casting from one integer or pointer type to another of
// the same size. Instead of casting the pointer before the load, cast
// the result of the loaded value.
Value *NewLoad = IC.InsertNewInstBefore(new LoadInst(CastOp,
CI->getName(),
LI.isVolatile()),LI);
// Now cast the result of the load.
return new CastInst(NewLoad, LI.getType());
}
}
}
return 0;