[llvm-bugs] [Bug 27594] New: AVX _mm256_extract_epi8 broken

[via llvm-bugs]

https://llvm.org/bugs/show_bug.cgi?id=27594

            Bug ID: 27594
           Summary: AVX _mm256_extract_epi8 broken
           Product: clang
           Version: 3.7
          Hardware: PC
                OS: FreeBSD
            Status: NEW
          Severity: normal
          Priority: P
         Component: -New Bugs
          Assignee: unassignedclangbugs at nondot.org
          Reporter: rozhuk.im at gmail.com
                CC: llvm-bugs at lists.llvm.org
    Classification: Unclassified

I try port some SSE code to AVX and found that clang instricts
_mm256_extract_epi8 broken:

_mm256_extract_epi8(__aymm0, 0) - BAD result
_mm256_extract_epi8(__aymm0, 0) & 0xff - OK
_mm_extract_epi8(_mm256_extractf128_si256(__aymm0, 0), 0) - OK

Same time: _mm256_extract_epi8(__aymm0, 0) build with GCC - OK.


CLANG:
static __inline int __attribute__((__always_inline__, __nodebug__))
_mm256_extract_epi8(__m256i __a, int const __imm)
{
  __v32qi __b = (__v32qi)__a;
  return __b[__imm & 31];
}


GCC:
extern __inline int __attribute__((__gnu_inline__, __always_inline__,
__artificial__)) 
_mm256_extract_epi8 (__m256i const __X, int const __N) 
{ 
  __m128i __Y = _mm256_extractf128_si256 (__X, __N >> 4); 
  return _mm_extract_epi8 (__Y, __N % 16); 
}



_mm256_extract_epi16, _mm256_extract_epi32 may be affected too.
Tested with: Clang 3.4.1, 3.6, 3.7 and GCC 4.8.5

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