some clang AVX instricts looks broken

[cbergstrom at pathscale.com]

I doubt this is fbsd specific? Wouldn't it be better to report this to clang upstream?

  Original Message  
From: Rozhuk Ivan
Sent: Monday, May 2, 2016 04:51
To: freebsd-hackers at freebsd.org; Rozhuk Ivan
Subject: some clang AVX instricts looks broken

Hi!

I try port some SSE code to AVX and found that clang instricts _mm256_extract* 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); 
}


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