[llvm] r211976 - [x86] Fix a bug in the v8i16 shuffling exposed by the new splat-like

Chandler Carruth chandlerc at gmail.com
Fri Jun 27 22:46:28 PDT 2014


Author: chandlerc
Date: Sat Jun 28 00:46:28 2014
New Revision: 211976

URL: http://llvm.org/viewvc/llvm-project?rev=211976&view=rev
Log:
[x86] Fix a bug in the v8i16 shuffling exposed by the new splat-like
lowering for v16i8.

ASan and some bots caught this bug with existing test cases. Fixing it
even fixed a miscompile with one of the test cases. I'm still a bit
suspicious of this test case as I've not taken a proper amount of time
to think about it, but the fix here is strict goodness.

Modified:
    llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
    llvm/trunk/test/CodeGen/X86/vector-shuffle-128-v16.ll

Modified: llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86ISelLowering.cpp?rev=211976&r1=211975&r2=211976&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86ISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86ISelLowering.cpp Sat Jun 28 00:46:28 2014
@@ -7535,7 +7535,7 @@ static SDValue lowerV8I16BasicBlendVecto
       } else {
         // Otherwise pin the low inputs.
         for (int GoodInput : GoodInputs)
-          MoveMask[Mask[GoodInput]] = Mask[GoodInput] - MaskOffset;
+          MoveMask[Mask[GoodInput] - MaskOffset] = Mask[GoodInput] - MaskOffset;
       }
 
       int MoveMaskIdx =

Modified: llvm/trunk/test/CodeGen/X86/vector-shuffle-128-v16.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/vector-shuffle-128-v16.ll?rev=211976&r1=211975&r2=211976&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/vector-shuffle-128-v16.ll (original)
+++ llvm/trunk/test/CodeGen/X86/vector-shuffle-128-v16.ll Sat Jun 28 00:46:28 2014
@@ -63,14 +63,15 @@ define <16 x i8> @shuffle_v16i8_00_00_00
 ; CHECK-SSE2-NEXT:    pxor %xmm1, %xmm1
 ; CHECK-SSE2-NEXT:    movdqa %xmm0, %xmm2
 ; CHECK-SSE2-NEXT:    punpcklbw %xmm1, %xmm2
-; CHECK-SSE2-NEXT:    pshufd {{.*}} # xmm2 = xmm2[2,1,2,3]
+; CHECK-SSE2-NEXT:    pshufd {{.*}} # xmm2 = xmm2[0,2,2,3]
+; CHECK-SSE2-NEXT:    pshuflw {{.*}} # xmm2 = xmm2[0,2,2,3,4,5,6,7]
 ; CHECK-SSE2-NEXT:    punpckhbw %xmm1, %xmm0
 ; CHECK-SSE2-NEXT:    pshufd {{.*}} # xmm0 = xmm0[0,2,2,3]
 ; CHECK-SSE2-NEXT:    pshuflw {{.*}} # xmm0 = xmm0[0,2,2,3,4,5,6,7]
 ; CHECK-SSE2-NEXT:    punpcklwd %xmm2, %xmm0
-; CHECK-SSE2-NEXT:    pshufd {{.*}} # xmm0 = xmm0[0,1,0,3]
+; CHECK-SSE2-NEXT:    pshufd {{.*}} # xmm0 = xmm0[0,1,2,1]
 ; CHECK-SSE2-NEXT:    pshuflw {{.*}} # xmm0 = xmm0[1,0,2,3,4,5,6,7]
-; CHECK-SSE2-NEXT:    pshufhw {{.*}} # xmm0 = xmm0[0,1,2,3,5,5,6,7]
+; CHECK-SSE2-NEXT:    pshufhw {{.*}} # xmm0 = xmm0[0,1,2,3,7,5,6,7]
 ; CHECK-SSE2-NEXT:    packuswb %xmm0, %xmm0
 ; CHECK-SSE2-NEXT:    punpcklbw %xmm0, %xmm0
 ; CHECK-SSE2-NEXT:    pshufd {{.*}} # xmm0 = xmm0[0,2,0,1]





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