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[x86] Fix another miscompile found through fuzz testing the new vector

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shuffle lowering.

This is closely related to the previous one. Here we failed to use the
source offset when swapping in the other case -- where we end up
swapping the *final* shuffle. The cause of this bug is a bit different:
I simply wasn't thinking about the fact that this mask is actually
a slice of a wide mask and thus has numbers that need SourceOffset
applied. Simple fix. Would be even more simple with an algorithm-y thing
to use here, but correctness first. =]

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215095 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chandler Carruth 2014-08-07 10:37:35 +00:00
parent 0651861b7b
commit 0e89fbb120
2 changed files with 21 additions and 4 deletions
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8
lib/Target/X86/X86ISelLowering.cpp
View File

@ -7546,10 +7546,10 @@ static SDValue lowerV8I16SingleInputVectorShuffle(
// We also have to update the final source mask in this case because
// it may need to undo the above swap.
for (int &M : FinalSourceHalfMask)
if (M == (InputsFixed[0] ^ 1))
M = InputsFixed[1];
else if (M == InputsFixed[1])
M = InputsFixed[0] ^ 1;
if (M == (InputsFixed[0] ^ 1) + SourceOffset)
M = InputsFixed[1] + SourceOffset;
else if (M == InputsFixed[1] + SourceOffset)
M = InputsFixed[0] ^ 1 + SourceOffset;
InputsFixed[1] = InputsFixed[0] ^ 1;
}

17
test/CodeGen/X86/vector-shuffle-128-v8.ll
View File

@ -238,6 +238,23 @@ define <8 x i16> @shuffle_v8i16_66751643(<8 x i16> %a, <8 x i16> %b) {
ret <8 x i16> %shuffle
}
define <8 x i16> @shuffle_v8i16_60514754(<8 x i16> %a, <8 x i16> %b) {
; SSE2-LABEL: @shuffle_v8i16_60514754
; SSE2: # BB#0:
; SSE2-NEXT: pshufhw {{.*}} # xmm0 = xmm0[0,1,2,3,6,5,4,7]
; SSE2-NEXT: pshufd {{.*}} # xmm0 = xmm0[0,2,2,3]
; SSE2-NEXT: pshuflw {{.*}} # xmm0 = xmm0[2,0,3,1,4,5,6,7]
; SSE2-NEXT: pshufhw {{.*}} # xmm0 = xmm0[0,1,2,3,6,7,5,6]
; SSE2-NEXT: retq
;
; SSSE3-LABEL: @shuffle_v8i16_60514754
; SSSE3: # BB#0:
; SSSE3-NEXT: pshufb {{.*}} # xmm0 = xmm0[12,13,0,1,10,11,2,3,8,9,14,15,10,11,8,9]
; SSSE3-NEXT: retq
%shuffle = shufflevector <8 x i16> %a, <8 x i16> undef, <8 x i32> <i32 6, i32 0, i32 5, i32 1, i32 4, i32 7, i32 5, i32 4>
ret <8 x i16> %shuffle
}
define <8 x i16> @shuffle_v8i16_00444444(<8 x i16> %a, <8 x i16> %b) {
; SSE2-LABEL: @shuffle_v8i16_00444444
; SSE2: # BB#0: