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<base href="http://llvm.org/bugs/" />
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - LCSSA and SSAUpdater incorrectly update dbg.value"
href="http://llvm.org/bugs/show_bug.cgi?id=15501">15501</a>
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<th>Summary</th>
<td>LCSSA and SSAUpdater incorrectly update dbg.value
</td>
</tr>
<tr>
<th>Product</th>
<td>new-bugs
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
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<th>OS</th>
<td>All
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>new bugs
</td>
</tr>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>atrick@apple.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=10170" name="attach_10170" title="Contrived test case">attachment 10170</a> <a href="attachment.cgi?id=10170&action=edit" title="Contrived test case">[details]</a></span>
Contrived test case
clang -g -c -emit-llvm -S loop.c -O3 -mllvm -disable-llvm-optzns -o loop.ll
opt loop.ll -O3 -S -o loop-O3.ll
Notice that the dbg.value inside the loop now refers to the LCSSA value outside
the loop.
if.end2: ; preds = %if.end
%call3 = tail call i32 (...)* @bar() #2, !dbg !21
%dec = add nsw i32 %dec5, -1, !dbg !17
tail call void @llvm.dbg.value(metadata !{i32 %dec.lcssa}, i64 0, metadata
!12), !dbg !17
%cmp = icmp slt i32 %dec, 0, !dbg !19
br i1 %cmp, label %while.end, label %if.end, !dbg !19
while.end: ; preds = %if.end2, %if.end,
%entry
%dec.lcssa = phi i32 [ %dec3, %entry ], [ %dec5, %if.end ], [ %dec, %if.end2
]
llc does yield an assert, but it isn't very helpful.
Assertion failed: (TheCU && "Unable to find compile unit!"), function
beginFunction, file /Volumes/Source/fix/lib/CodeGen/AsmPrinter/DwarfDebug.cpp,
line 1362.
This is a general problem with RAUW on ValueHandle. It would be easy to fix
this test case without fixing the general problem. RAUW should *not* be called
by LCSSA or SSAUpdater.
See PR15413.</pre>
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