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<base href="https://bugs.llvm.org/">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Broadcasting the high word in AVX2"
href="https://bugs.llvm.org/show_bug.cgi?id=47194">47194</a>
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<th>Summary</th>
<td>Broadcasting the high word in AVX2
</td>
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<th>Product</th>
<td>libraries
</td>
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<th>Version</th>
<td>trunk
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Linux
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>enhancement
</td>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>Backend: X86
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>david.bolvansky@gmail.com
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<th>CC</th>
<td>craig.topper@gmail.com, llvm-bugs@lists.llvm.org, llvm-dev@redking.me.uk, spatel+llvm@rotateright.com
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<div>
<pre>From
<a href="https://stackoverflow.com/questions/57505111/broadcasting-the-high-word-in-avx2">https://stackoverflow.com/questions/57505111/broadcasting-the-high-word-in-avx2</a>:
#include <immintrin.h>
__m256i bcast_mse(__m256i v) {
__m256i temp = _mm256_permute2x128_si256(v, v, 0x11);
__m256i ctrl = _mm256_set_epi8(
15, 14, 15, 14, 15, 14, 15, 14,
15, 14, 15, 14, 15, 14, 15, 14,
15, 14, 15, 14, 15, 14, 15, 14,
15, 14, 15, 14, 15, 14, 15, 14
);
return _mm256_shuffle_epi8(temp, ctrl);
}
Clang -O3 -mavx2:
bcast_mse(long long __vector(4)): # @bcast_mse(long long
__vector(4))
vpshufhw ymm0, ymm0, 255 # ymm0 =
ymm0[0,1,2,3,7,7,7,7,8,9,10,11,15,15,15,15]
vpshufd ymm0, ymm0, 170 # ymm0 = ymm0[2,2,2,2,6,6,6,6]
vpermq ymm0, ymm0, 170 # ymm0 = ymm0[2,2,2,2]
ret
GCC/ICC -O3 -mavx2:
bcast_mse(__m256i):
vperm2i128 ymm1, ymm0, ymm0, 17 #4.20
vpshufb ymm0, ymm1, YMMWORD PTR .L_2il0floatpacket.0[rip] #11.12
ret #11.12
.L_2il0floatpacket.0:
.long
0x0f0e0f0e,0x0f0e0f0e,0x0f0e0f0e,0x0f0e0f0e,0x0f0e0f0e,0x0f0e0f0e,0x0f0e0f0e,0x0f0e0f0e
Godbolt:
<a href="https://godbolt.org/z/cWb9Po">https://godbolt.org/z/cWb9Po</a></pre>
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