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[x86] Fix another miscompile in the new vector shuffle lowering found 

through the new fuzzer.

This one is great: bad operator precedence led the modulus to happen at
the wrong point. All the asserts didn't fire because there were usually
the right values past the end of the 4 element region we were looking
at. Probably could have gotten a crash here with ASan + fuzzing, but the
correctness tests pinpointed this really nicely.

llvm-svn: 215092
This commit is contained in:
Chandler Carruth 2014-08-07 09:45:02 +00:00
parent f55eb450e5
commit 78494364d1
2 changed files with 23 additions and 1 deletions
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2
llvm/lib/Target/X86/X86ISelLowering.cpp
View File

@ -7735,7 +7735,7 @@ static SDValue lowerV8I16BasicBlendVectorShuffle(SDLoc DL, SDValue V1,
[](int M) { return M >= 0; }) -
std::begin(MoveMask);
int MoveMaskIdx =
(((GoodMaskIdx - MoveOffset) & ~1) + 2 % 4) + MoveOffset;
((((GoodMaskIdx - MoveOffset) & ~1) + 2) % 4) + MoveOffset;
assert(MoveMask[MoveMaskIdx] == -1 && "Expected empty slot");
assert(MoveMask[MoveMaskIdx + 1] == -1 && "Expected empty slot");
MoveMask[MoveMaskIdx] = Mask[BadInputs[0]] - MaskOffset;

22
llvm/test/CodeGen/X86/vector-shuffle-128-v8.ll
View File

@ -524,6 +524,28 @@ define <8 x i16> @shuffle_v8i16_0213cedf(<8 x i16> %a, <8 x i16> %b) {
ret <8 x i16> %shuffle
}
define <8 x i16> @shuffle_v8i16_443aXXXX(<8 x i16> %a, <8 x i16> %b) {
; SSE2-LABEL: @shuffle_v8i16_443aXXXX
; SSE2: # BB#0:
; SSE2-NEXT: pshufd {{.*}} # xmm0 = xmm0[2,1,2,3]
; SSE2-NEXT: pshuflw {{.*}} # xmm0 = xmm0[0,0,2,3,4,5,6,7]
; SSE2-NEXT: punpcklwd %xmm1, %xmm0 # xmm0 = xmm0[0],xmm1[0],xmm0[1],xmm1[1],xmm0[2],xmm1[2],xmm0[3],xmm1[3]
; SSE2-NEXT: pshuflw {{.*}} # xmm0 = xmm0[0,2,2,3,4,5,6,7]
; SSE2-NEXT: pshufhw {{.*}} # xmm0 = xmm0[0,1,2,3,6,5,6,7]
; SSE2-NEXT: pshufd {{.*}} # xmm0 = xmm0[0,2,2,3]
; SSE2-NEXT: retq
;
; SSSE3-LABEL: @shuffle_v8i16_443aXXXX
; SSSE3: # BB#0:
; SSSE3-NEXT: pshufd {{.*}} # xmm0 = xmm0[2,1,2,3]
; SSSE3-NEXT: pshuflw {{.*}} # xmm0 = xmm0[0,0,2,3,4,5,6,7]
; SSSE3-NEXT: punpcklwd %xmm1, %xmm0 # xmm0 = xmm0[0],xmm1[0],xmm0[1],xmm1[1],xmm0[2],xmm1[2],xmm0[3],xmm1[3]
; SSSE3-NEXT: pshufb {{.*}} # xmm0 = xmm0[0,1,4,5,12,13,10,11,{{[0-9]+,[0-9]+,[0-9]+,[0-9]+,[0-9]+,[0-9]+,[0-9]+,[0-9]+}}]
; SSSE3-NEXT: retq
%shuffle = shufflevector <8 x i16> %a, <8 x i16> %b, <8 x i32> <i32 4, i32 4, i32 3, i32 10, i32 undef, i32 undef, i32 undef, i32 undef>
ret <8 x i16> %shuffle
}
define <8 x i16> @shuffle_v8i16_032dXXXX(<8 x i16> %a, <8 x i16> %b) {
; SSE2-LABEL: @shuffle_v8i16_032dXXXX
; SSE2: # BB#0: