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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - ARM doesn't respect the DbgLoc of a comparison used in a branch"
href="http://llvm.org/bugs/show_bug.cgi?id=22417">22417</a>
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<th>Summary</th>
<td>ARM doesn't respect the DbgLoc of a comparison used in a branch
</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>Linux
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Keywords</th>
<td>wrong-debug
</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>Backend: ARM
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
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<th>Reporter</th>
<td>dblaikie@gmail.com
</td>
</tr>
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<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Code like:
%tobool = icmp ..., !dbg !10
br i1 %tobool, ..., !dbg !11
....
!10 = !MDLocation(line: 2, ...
!11 = !MDLocation(line: 3, ...
Generates
CMPri %vreg7<kill>, 0, pred:14, pred:%noreg, %CPSR<imp-def>; GPR:%vreg7
dbg:line.cpp:3
Bcc <BB#2>, pred:0, pred:%CPSR; dbg:line.cpp:3
losing the correct location (line 2) in the comparison instruction.
This seems to be because br_cc is considered legal, so the brcond and
comparison is merged into a br_cc, then it's split out again (by a MorphNodeTo
call).
That's my /really vague/ understanding, anyway. Much of that analysis may be
hokum because I'm not very familiar with SelectionDAG, etc.
Test case test/DebugInfo/ARM/line.test is the authoritative demonstration of
the buggy behavior.</pre>
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