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Canonicalize bitcasts between types like <1 x i64> and i64 to 

insertelement/extractelement.

I'm not entirely sure this is precisely what we want to do: should we 
prefer bitcast(insertelement) or insertelement(bitcast)?  Similarly. should we 
prefer extractelement(bitcast) or bitcast(extractelement)?

llvm-svn: 76345
This commit is contained in:
Eli Friedman 2009-07-18 23:06:53 +00:00
parent 67038c1333
commit 048e78fc5b
2 changed files with 46 additions and 0 deletions
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24
llvm/lib/Transforms/Scalar/InstructionCombining.cpp
View File

@ -9033,6 +9033,29 @@ Instruction *InstCombiner::visitBitCast(BitCastInst &CI) {
}
}
if (const VectorType *DestVTy = dyn_cast<VectorType>(DestTy)) {
if (DestVTy->getNumElements() == 1) {
if (!isa<VectorType>(SrcTy)) {
Value *Elem = InsertCastBefore(Instruction::BitCast, Src,
DestVTy->getElementType(), CI);
return InsertElementInst::Create(Context->getUndef(DestTy), Elem,
Context->getNullValue(Type::Int32Ty));
}
// FIXME: Canonicalize bitcast(insertelement) -> insertelement(bitcast)
}
}
if (const VectorType *SrcVTy = dyn_cast<VectorType>(SrcTy)) {
if (SrcVTy->getNumElements() == 1) {
if (!isa<VectorType>(DestTy)) {
Instruction *Elem =
new ExtractElementInst(Src, Context->getNullValue(Type::Int32Ty));
InsertNewInstBefore(Elem, CI);
return CastInst::Create(Instruction::BitCast, Elem, DestTy);
}
}
}
if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(Src)) {
if (SVI->hasOneUse()) {
// Okay, we have (bitconvert (shuffle ..)). Check to see if this is
@ -12477,6 +12500,7 @@ Instruction *InstCombiner::visitExtractElementInst(ExtractElementInst &EI) {
Context->getConstantInt(Type::Int32Ty, SrcIdx, false));
}
}
// FIXME: Canonicalize extractelement(bitcast) -> bitcast(extractelement)
}
return 0;
}

22
llvm/test/Transforms/InstCombine/bitcast-vec-canon.ll Normal file
View File

@ -0,0 +1,22 @@
; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep element | count 4
define double @a(<1 x i64> %y) {
%c = bitcast <1 x i64> %y to double
ret double %c
}
define i64 @b(<1 x i64> %y) {
%c = bitcast <1 x i64> %y to i64
ret i64 %c
}
define <1 x i64> @c(double %y) {
%c = bitcast double %y to <1 x i64>
ret <1 x i64> %c
}
define <1 x i64> @d(i64 %y) {
%c = bitcast i64 %y to <1 x i64>
ret <1 x i64> %c
}