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Make demanded-elt simplification for shufflevector slightly stronger. Spotted by inspection. 

llvm-svn: 139768
This commit is contained in:
Eli Friedman 2011-09-15 01:14:29 +00:00
parent 88c1b77f74
commit 888bea0b95
2 changed files with 14 additions and 0 deletions
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3
llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
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@ -962,6 +962,9 @@ Value *InstCombiner::SimplifyDemandedVectorElts(Value *V, APInt DemandedElts,
unsigned MaskVal = Shuffle->getMaskValue(i);
if (MaskVal == -1u) {
UndefElts.setBit(i);
} else if (!DemandedElts[i]) {
NewUndefElts = true;
UndefElts.setBit(i);
} else if (MaskVal < LHSVWidth) {
if (UndefElts4[MaskVal]) {
NewUndefElts = true;

11
llvm/test/Transforms/InstCombine/vec_demanded_elts.ll
View File

@ -152,3 +152,14 @@ entry:
ret <4 x i32> %0
}
declare <4 x i32> @llvm.x86.sse41.pmovzxwd(<8 x i16>) nounwind readnone
define <4 x float> @dead_shuffle_elt(<4 x float> %x, <2 x float> %y) nounwind {
entry:
; CHECK: define <4 x float> @dead_shuffle_elt
; CHECK: shufflevector <2 x float> %y, <2 x float> undef, <4 x i32> <i32 0, i32 1, i32 undef, i32 undef>
%shuffle.i = shufflevector <2 x float> %y, <2 x float> %y, <4 x i32> <i32 0, i32 1, i32 0, i32 1>
%shuffle9.i = shufflevector <4 x float> %x, <4 x float> %shuffle.i, <4 x i32> <i32 4, i32 5, i32 2, i32 3>
ret <4 x float> %shuffle9.i
}