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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - (New)GVN should be able to handle memsets with the same value even if they alias"
href="http://bugs.llvm.org/show_bug.cgi?id=32571">32571</a>
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<th>Summary</th>
<td>(New)GVN should be able to handle memsets with the same value even if they alias
</td>
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<th>Product</th>
<td>libraries
</td>
</tr>
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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>All
</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>Scalar Optimizations
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
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<th>Reporter</th>
<td>keno@alumni.harvard.edu
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
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<p>
<div>
<pre>E.g. in the following example,
```
declare void @llvm.memset.p0i8.i64(i8*, i8, i64, i32, i1)
define double @memset_same_value(double *%a, double *%b) {
%acast = bitcast double *%a to i8*
%bcast = bitcast double *%b to i8*
call void @llvm.memset.p0i8.i64(i8* %acast, i8 0, i64 8, i32 8, i1 0)
call void @llvm.memset.p0i8.i64(i8* %bcast, i8 0, i64 8, i32 8, i1 0)
%la = load double, double* %a
ret double %la
}
```
GVN won't fold the load to 0, because it's afraid that the second memset
aliases it. While this may be true, since it's storing the same value, it
shouldn't matter.</pre>
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