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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - can't delete empty, terminating, strided loop"
href="http://llvm.org/bugs/show_bug.cgi?id=19183">19183</a>
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<th>Summary</th>
<td>can't delete empty, terminating, strided loop
</td>
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<tr>
<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>Linux
</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
</td>
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<th>Component</th>
<td>Scalar Optimizations
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>richard-llvm@metafoo.co.uk
</td>
</tr>
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<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
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<th>Classification</th>
<td>Unclassified
</td>
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<p>
<div>
<pre>We can't delete the trivial terminating empty loop in this code:
void f(unsigned k) {
for (unsigned n = 0; n != (k & -32); n += 32) {
}
}
The above results in this IR at -O3:
define void @_Z1fj(i32 %k) #0 {
entry:
%and = and i32 %k, -32
br label %for.cond
for.cond: ; preds = %for.cond, %entry
%n.0 = phi i32 [ 0, %entry ], [ %add, %for.cond ]
%cmp = icmp eq i32 %n.0, %and
%add = add i32 %n.0, 32
br i1 %cmp, label %for.end, label %for.cond
for.end: ; preds = %for.cond
ret void
}
Such loop structures are created by the vectorizer.</pre>
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