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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 --- - AVX512: incorrect code generation for very basic code"
href="https://llvm.org/bugs/show_bug.cgi?id=30430">30430</a>
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<tr>
<th>Summary</th>
<td>AVX512: incorrect code generation for very basic code
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>All
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>Backend: X86
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>wenzel.jakob@epfl.ch
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Hi,
I'm getting invalid code for a very basic snippet which constructs a packed
float array and prints it. I suspect an issue with calling conventions. The
problem only appears at optimization level -O0.
Observed output:
$ clang test.c -o test -mavx512f -stdlib=libc++ -O0
$ ./test
0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000
9.000000 10.000000 11.000000 12.000000 13.000000 14.000000 15.000000 16.000000
Expected output:
$ ./test
1.000000 2.000000 3.000000 4.000000 5.000000 6.000000 7.000000 8.000000
9.000000 10.000000 11.000000 12.000000 13.000000 14.000000 15.000000 16.000000
For reference, this is with
$ clang -v
clang version 4.0.0 (trunk 281812)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /usr/local/bin
Found candidate GCC installation: /usr/lib/gcc/x86_64-redhat-linux/4.8.2
Found candidate GCC installation: /usr/lib/gcc/x86_64-redhat-linux/4.8.5
Selected GCC installation: /usr/lib/gcc/x86_64-redhat-linux/4.8.5
Candidate multilib: .;@m64
Candidate multilib: 32;@m32
Selected multilib: .;@m64
===============
#include <immintrin.h>
__m512 makefloat(float f1, float f2, float f3, float f4, float f5, float f6,
float f7, float f8, float f9, float f10, float f11, float f12, float f13, float
f14, float f15, float f16) {
return _mm512_setr_ps(f1, f2, f3, f4, f5, f6, f7, f8, f9, f10, f11, f12,
f13, f14, f15, f16);
}
int main(int argc, char *argv[]) {
__m512 x = makefloat(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
16);
float result[16];
_mm512_storeu_ps(result, x);
for (int i = 0; i < 16; ++i)
printf("%f ", result[i]);
return 0;
}</pre>
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