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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Poor -Rpass-analysis=loop-vectorize diagnostic message for (acceptable) failure to vectorize Objective-C fast enumeration loops"
href="https://llvm.org/bugs/show_bug.cgi?id=28375">28375</a>
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<th>Summary</th>
<td>Poor -Rpass-analysis=loop-vectorize diagnostic message for (acceptable) failure to vectorize Objective-C fast enumeration loops
</td>
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<tr>
<th>Product</th>
<td>new-bugs
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
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<th>Hardware</th>
<td>Macintosh
</td>
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<th>OS</th>
<td>MacOS X
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>normal
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>new bugs
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>sean@rogue-research.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
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</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=16663" name="attach_16663" title="Repro case">attachment 16663</a> <a href="attachment.cgi?id=16663&action=edit" title="Repro case">[details]</a></span>
Repro case
I'm not at all surprised that clang does not autovectorize even simple
Objective-C fast enumeration loops like below:
-------test.m----------
#import <Foundation/Foundation.h>
int main(void)
{
int sum = 0;
for (NSNumber* n in @[@1, @2, @3]) {
sum++;
}
return sum;
}
-----------------------
But the diagnostic is poor:
$ clang --version
clang version 3.9.0 (trunk 274259)
$ clang -S -fvectorize -O3 -Rpass-analysis=loop-vectorize ~/Desktop/test.m
/Users/sean/Desktop/test.m:6:2: remark: loop not vectorized: control flow
cannot be substituted for a select [-Rpass-analysis=loop-vectorize]
for (NSNumber* n in @[@6, @7, @3]) {
^
A message like "NSFastEnumeration loops can never be vectorized" would be
better IMHO.</pre>
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