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[x86] prevent infinite looping from inverse shuffle transforms

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llvm-svn: 355713
This commit is contained in:
Sanjay Patel 2019-03-08 19:20:28 +00:00
parent 7f9054e04b
commit 0e690383e6
2 changed files with 18 additions and 1 deletions
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7
lib/Target/X86/X86ISelLowering.cpp
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@ -9850,11 +9850,16 @@ static bool is128BitUnpackShuffleMask(ArrayRef<int> Mask) {
MVT EltVT = MVT::getIntegerVT(128 / Mask.size());
MVT VT = MVT::getVectorVT(EltVT, Mask.size());
// We can't assume a canonical shuffle mask, so try the commuted version too.
SmallVector<int, 4> CommutedMask(Mask.begin(), Mask.end());
ShuffleVectorSDNode::commuteMask(CommutedMask);
// Match any of unary/binary or low/high.
for (unsigned i = 0; i != 4; ++i) {
SmallVector<int, 16> UnpackMask;
createUnpackShuffleMask(VT, UnpackMask, (i >> 1) % 2, i % 2);
if (isTargetShuffleEquivalent(Mask, UnpackMask))
if (isTargetShuffleEquivalent(Mask, UnpackMask) ||
isTargetShuffleEquivalent(CommutedMask, UnpackMask))
return true;
}
return false;

12
test/CodeGen/X86/vector-shuffle-128-unpck.ll
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@ -221,3 +221,15 @@ define <16 x i8> @unpckl_unary_extracted_v32i8(<32 x i8> %x) {
ret <16 x i8> %r
}
; This would infinite loop because we did not recognize the unpack shuffle mask in commuted form.
define <8 x i32> @extract_unpckl_v8i32(<8 x i32> %a) {
; ALL-LABEL: extract_unpckl_v8i32:
; ALL: # %bb.0:
; ALL-NEXT: vextractf128 $1, %ymm0, %xmm1
; ALL-NEXT: vunpcklps {{.*#+}} xmm0 = xmm1[0],xmm0[0],xmm1[1],xmm0[1]
; ALL-NEXT: retq
%shuffle = shufflevector <8 x i32> %a, <8 x i32> undef, <8 x i32> <i32 4, i32 undef, i32 5, i32 1, i32 undef, i32 undef, i32 undef, i32 undef>
ret <8 x i32> %shuffle
}