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<base href="https://bugs.llvm.org/">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - [coroutines] Clang emits duplicate debug information for 'this' variable"
href="https://bugs.llvm.org/show_bug.cgi?id=33492">33492</a>
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<th>Summary</th>
<td>[coroutines] Clang emits duplicate debug information for 'this' variable
</td>
</tr>
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<th>Product</th>
<td>clang
</td>
</tr>
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<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Windows NT
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>enhancement
</td>
</tr>
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<th>Priority</th>
<td>P
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</tr>
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<th>Component</th>
<td>LLVM Codegen
</td>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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</tr>
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<th>Reporter</th>
<td>eric@efcs.ca
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
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<pre>Created <span class=""><a href="attachment.cgi?id=18654" name="attach_18654" title="reproducer.cpp">attachment 18654</a> <a href="attachment.cgi?id=18654&action=edit" title="reproducer.cpp">[details]</a></span>
reproducer.cpp
Currently, under certain conditions, Clang/LLVM will hit the following
assertion when processing coroutine code.
clang-5.0: /home/eric/full-llvm/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h:131:
void llvm::DbgVariable::addMMIEntry(const llvm::DbgVariable &): Assertion
`V.Var == Var && "conflicting variable"' failed.
I've only been able to hit this assertion when passing `-g -O2` (See attached
reproducer, compile as "clang++ -std=c++11 -fcoroutines-ts -g -O2 test.cpp").
A little investigation suggests that it's the 'this' variable which is being
duplicated. I have no clue why this is happening.
The relevant bit of the LLVM IR that clang emits appears to be this:
!175 = !DISubprogram(name: "unhandled_exception", linkageName:
"_ZN4func12promise_type19unhandled_exceptionEv", scope: !119, file: !1, line:
106, type: !173, isLocal: false, isDefinition: false, scopeLine: 106, flags:
DIFlagPrototyped, isOptimized: true)
[...]
!178 = !DILocalVariable(name: "this", arg: 1, scope: !179, type: !183, flags:
DIFlagArtificial | DIFlagObjectPointer)
!179 = distinct !DISubprogram(name: "return_void", linkageName:
"_ZN4func12promise_type11return_voidEv", scope: !35, file: !1, line: 105, type:
!93, isLocal: false, isDefinition: true, scopeLine: 105, flags:
DIFlagPrototyped, isOptimized: true, unit: !0, declaration: !92, variables:
!180)
!180 = !{!181}
!181 = !DILocalVariable(name: "this", arg: 1, scope: !179, type: !182, flags:
DIFlagArtificial | DIFlagObjectPointer)
[...]</pre>
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