[PATCH] D81547: [X86][SSE] MatchVectorAllZeroTest - handle OR vector reductions

Mon Jun 22 12:54:37 PDT 2020

hans added a comment.

This seems to be causing Chromium test failures. Diffing the asm looks suspicious:

   Disassembly of section .text._ZN5glcts18ComputeShaderTestsC2ERN4deqp7ContextE:
  @@ -29795,7 +29795,7 @@
       11c4:      66 0f 63 c3             packsswb %xmm3,%xmm0
       11c8:      66 0f d7 c0             pmovmskb %xmm0,%eax
       11cc:      66 85 c0                test   %ax,%ax
  -    11cf:      0f 84 65 01 00 00       je     133a <_ZN5glcts12_GLOBAL__N_128AdvancedPipelineComputeChain3RunEv+0x133a>
  +    11cf:      0f 85 65 01 00 00       jne    133a <_ZN5glcts12_GLOBAL__N_128AdvancedPipelineComputeChain3RunEv+0x133a>
       11d5:      49 8b 45 20             mov    0x20(%r13),%rax
       11d9:      48 8b 00                mov    (%rax),%rax
       11dc:      48 8b 40 10             mov    0x10(%rax),%rax
  @@ -29894,7 +29894,7 @@
       137d:      66 0f 63 c2             packsswb %xmm2,%xmm0
       1381:      66 0f d7 c0             pmovmskb %xmm0,%eax
       1385:      66 85 c0                test   %ax,%ax
  -    1388:      0f 84 64 01 00 00       je     14f2 <_ZN5glcts12_GLOBAL__N_128AdvancedPipelineComputeChain3RunEv+0x14f2>
  +    1388:      0f 85 64 01 00 00       jne    14f2 <_ZN5glcts12_GLOBAL__N_128AdvancedPipelineComputeChain3RunEv+0x14f2>
       138e:      49 8b 45 20             mov    0x20(%r13),%rax
       1392:      48 8b 00                mov    (%rax),%rax
       1395:      48 8b 40 10             mov    0x10(%rax),%rax

It seems the conditions on the jumps there are getting flipped, which really looks like a bug. I've posted a repro here: https://bugs.chromium.org/p/chromium/issues/detail?id=1097758#c9

I've reverted in 1357c065783e8d66c9db4be59aca389d1dc6c05f <https://reviews.llvm.org/rG1357c065783e8d66c9db4be59aca389d1dc6c05f> in the meantime.

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D81547/new/

https://reviews.llvm.org/D81547