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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - AVX _mm256_extract_epi8 broken"
href="https://llvm.org/bugs/show_bug.cgi?id=27594">27594</a>
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<th>Summary</th>
<td>AVX _mm256_extract_epi8 broken
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<th>Product</th>
<td>clang
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<th>Version</th>
<td>3.7
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>FreeBSD
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>-New Bugs
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>rozhuk.im@gmail.com
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</tr>
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org
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<th>Classification</th>
<td>Unclassified
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<p>
<div>
<pre>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</pre>
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