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Implement InstCombine/cast.ll:test25, a case that occurs many times

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in spec


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@19953 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2005-01-31 05:51:45 +00:00
parent 0f991191eb
commit fcfe33acda
1 changed files with 56 additions and 0 deletions
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56
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -4622,6 +4622,7 @@ static Constant *GetGEPGlobalInitializer(Constant *C, ConstantExpr *CE) {
return C;
}
/// InstCombineLoadCast - Fold 'load (cast P)' -> cast (load P)' when possible.
static Instruction *InstCombineLoadCast(InstCombiner &IC, LoadInst &LI) {
User *CI = cast<User>(LI.getOperand(0));
Value *CastOp = CI->getOperand(0);
@ -4805,6 +4806,51 @@ Instruction *InstCombiner::visitLoadInst(LoadInst &LI) {
return 0;
}
/// InstCombineStoreToCast - Fold 'store V, (cast P)' -> store (cast V), P'
/// when possible.
static Instruction *InstCombineStoreToCast(InstCombiner &IC, StoreInst &SI) {
User *CI = cast<User>(SI.getOperand(1));
Value *CastOp = CI->getOperand(0);
const Type *DestPTy = cast<PointerType>(CI->getType())->getElementType();
if (const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType())) {
const Type *SrcPTy = SrcTy->getElementType();
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 store, cast
// the value to be stored.
Value *NewCast;
if (Constant *C = dyn_cast<Constant>(SI.getOperand(0)))
NewCast = ConstantExpr::getCast(C, SrcPTy);
else
NewCast = IC.InsertNewInstBefore(new CastInst(SI.getOperand(0),
SrcPTy,
SI.getOperand(0)->getName()+".c"), SI);
return new StoreInst(NewCast, CastOp);
}
}
}
return 0;
}
Instruction *InstCombiner::visitStoreInst(StoreInst &SI) {
Value *Val = SI.getOperand(0);
Value *Ptr = SI.getOperand(1);
@ -4837,6 +4883,16 @@ Instruction *InstCombiner::visitStoreInst(StoreInst &SI) {
return 0;
}
// If the pointer destination is a cast, see if we can fold the cast into the
// source instead.
if (CastInst *CI = dyn_cast<CastInst>(Ptr))
if (Instruction *Res = InstCombineStoreToCast(*this, SI))
return Res;
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr))
if (CE->getOpcode() == Instruction::Cast)
if (Instruction *Res = InstCombineStoreToCast(*this, SI))
return Res;
return 0;
}