This patch makes instcombine convert this:
%t = getelementptr float* cast ([2 x i32]* %str to float*), i32 %V
into this:
%t = getelementptr float* cast ([2 x i32]* %str to [2 x float]*), i32 0,
i32 %V
instead of this:
%s = getelementptr [2 x i32]* %str, i32 0, i32 %V
%t = bitcast i32* %s to float*
I'm not yet familiar with instcombine's canonicalization style; is this
a desireable change? It doesn't cause any regressions for me.
Dan
--
Dan Gohman, Cray Inc.
Index: InstructionCombining.cpp
===================================================================
RCS file: /var/cvs/llvm/llvm/lib/Transforms/Scalar/InstructionCombining.cpp,v
retrieving revision 1.731
diff -t -d -u -p -5 -r1.731 InstructionCombining.cpp
--- InstructionCombining.cpp
+++ InstructionCombining.cpp
@@ -8113,23 +8113,24 @@ Instruction *InstCombiner::visitGetEleme
// is a leading zero) we can fold the cast into this GEP.
GEP.setOperand(0, X);
return &GEP;
}
} else if (GEP.getNumOperands() == 2) {
- // Transform things like:
- // %t = getelementptr ubyte* cast ([2 x int]* %str to uint*), uint %V
- // into: %t1 = getelementptr [2 x int*]* %str, int 0, uint %V; cast
+ // transform: GEP cast ([2 x int]* %str to float*), uint %V
+ // into : GEP cast ([2 x int]* %str to [2 x float]*), int 0, uint %V
const Type *SrcElTy = cast<PointerType>(X->getType())->getElementType();
const Type
*ResElTy=cast<PointerType>(PtrOp->getType())->getElementType();
if (isa<ArrayType>(SrcElTy) &&
TD->getTypeSize(cast<ArrayType>(SrcElTy)->getElementType()) ==
TD->getTypeSize(ResElTy)) {
+ const Type *NewArrayTy =
+ ArrayType::get(ResElTy,
+ cast<ArrayType>(SrcElTy)->getNumElements());
Value *V = InsertNewInstBefore(
- new GetElementPtrInst(X, Constant::getNullValue(Type::Int32Ty),
- GEP.getOperand(1), GEP.getName()), GEP);
- // V and GEP are both pointer types --> BitCast
- return new BitCastInst(V, GEP.getType());
+ new BitCastInst(X, PointerType::get(NewArrayTy)), GEP);
+ return new GetElementPtrInst(V, Constant::getNullValue(Type::Int32Ty),
+ GEP.getOperand(1), GEP.getName());
}
// Transform things like:
// getelementptr sbyte* cast ([100 x double]* X to sbyte*), int %tmp
// (where tmp = 8*tmp2) into:
_______________________________________________
llvm-commits mailing list
llvm-commits@cs.uiuc.edu
http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
