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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 - Missed loop vectorization (fmul src[idx[i]], constant)"
href="https://bugs.llvm.org/show_bug.cgi?id=51427">51427</a>
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<th>Summary</th>
<td>Missed loop vectorization (fmul src[idx[i]], constant)
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
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<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
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<th>OS</th>
<td>Windows NT
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>enhancement
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>Loop Optimizer
</td>
</tr>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
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<th>Reporter</th>
<td>david.bolvansky@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
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</tr></table>
<p>
<div>
<pre>#include <stdint.h>
void mulPi(double * const __restrict__ dst,
double const * const __restrict__ src,
uint32_t const * const __restrict__ idx,
uint32_t const begin,
uint32_t const end)
{
for (uint32_t i = begin; i < end; ++i)
dst[i] = 3.141 * src[idx[i]];
}
GCC and ICC vectorizes this code just fine.
LLVM:
remark: the cost-model indicates that vectorization is not beneficial
[-Rpass-missed=loop-vectorize]
remark: the cost-model indicates that interleaving is not beneficial
[-Rpass-missed=loop-vectorize]
<a href="https://godbolt.org/z/4j44KKT3c">https://godbolt.org/z/4j44KKT3c</a></pre>
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