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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 - Loop Vectorizer does not handle masked gather"
href="https://bugs.llvm.org/show_bug.cgi?id=35879">35879</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Loop Vectorizer does not handle masked gather
</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>
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<th>OS</th>
<td>All
</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>Loop Optimizer
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>trass3r@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>#include <cstdint>
int foo(uint32_t* __restrict r, uint32_t* __restrict ptr)
{
for (int j = 0; j < 8; ++j)
if (r[j] < 1024)
r[j] = *(ptr++);
}
<a href="https://software.intel.com/en-us/node/523959">https://software.intel.com/en-us/node/523959</a>
$ clang -std=c++14 -O3 -S -fverbose-asm -march=haswell
-Rpass-missed=loop-vectorize -Rpass-analysis=loop-vectorize test.cpp
loop control flow is not understood by vectorizer
<a href="https://godbolt.org/g/8HNuay">https://godbolt.org/g/8HNuay</a>
Oddly enough when simply changing the return type to void the loop unroller
takes over and no vectorization is attempted at all (which is kind of common
with clang).</pre>
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</p>
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