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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - [InstCombine] should sub C, (zext i1) be canonicalized to a select?"
href="https://llvm.org/bugs/show_bug.cgi?id=30327">30327</a>
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<th>Summary</th>
<td>[InstCombine] should sub C, (zext i1) be canonicalized to a select?
</td>
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<th>Product</th>
<td>libraries
</td>
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<th>Version</th>
<td>trunk
</td>
</tr>
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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>normal
</td>
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>Scalar Optimizations
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>spatel+llvm@rotateright.com
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org
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<th>Classification</th>
<td>Unclassified
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</tr></table>
<p>
<div>
<pre>These are logically equivalent:
unsigned sel(bool x) {
if (x)
return 54;
else
return 55;
}
unsigned add(bool x) {
return 55 - x;
}
But the optimized IR is:
define i32 @sel(i1 zeroext %x) {
%s = select i1 %x, i32 54, i32 55
ret i32 %s
}
define i32 @add(i1 zeroext %x) {
%conv = zext i1 %x to i32
%sub = sub nsw i32 55, %conv
ret i32 %sub
}
Which one is canonical?</pre>
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