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<base href="https://llvm.org/bugs/" />
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - [Regression] Wrong codegen for AVX permute intrinsic"
href="https://llvm.org/bugs/show_bug.cgi?id=26667">26667</a>
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<tr>
<th>Summary</th>
<td>[Regression] Wrong codegen for AVX permute intrinsic
</td>
</tr>
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<th>Product</th>
<td>libraries
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
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<th>OS</th>
<td>Linux
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>Backend: X86
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
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<th>Reporter</th>
<td>Yunzhong_Gao@playstation.sony.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org, llvm-dev@redking.me.uk
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</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>// test.c
typedef double __m256d __attribute__((__vector_size__(32)));
typedef double __v4df __attribute__ ((__vector_size__ (32)));
#define _mm256_permute2f128_pd(V1, V2, M) \
(__m256d)__builtin_ia32_vperm2f128_pd256((__v4df)(V1), (__v4df)(V2), (M))
__m256d foo(__m256d Lhs, __m256d Rhs) {
return _mm256_permute2f128_pd(Lhs, Rhs, 50);
}
// end test.c
$ clang -O0 -S -mavx test.c -o -
Here is the assembly sequence produced by r260062:
andq $-32, %rsp
subq $96, %rsp
vmovapd %ymm0, 32(%rsp)
vmovapd %ymm1, (%rsp)
vmovapd 32(%rsp), %ymm0
# vperm2f128 $src3, $src2, $src1, $dst
# with mask=$50, $dst = $src2, so in this case, ymm0 <= ymm1
vperm2f128 $50, %ymm1, %ymm0, %ymm0 # ymm0 = ymm1[0,1,2,3]
And here is the assembly sequence produced by r260063 and later
andq $-32, %rsp
subq $128, %rsp
vmovapd %ymm0, 64(%rsp)
vmovapd %ymm1, 32(%rsp)
vmovapd 64(%rsp), %ymm0
vmovaps %ymm1, (%rsp) # 32-byte Spill
# and in this case, ymm0 is still ymm0</pre>
</div>
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