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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_CONFIRMED "
title="CONFIRMED - [DebugInfo@O2] ADCE needlessly deletes dbg.values"
href="https://bugs.llvm.org/show_bug.cgi?id=40688">40688</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>[DebugInfo@O2] ADCE needlessly deletes dbg.values
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux
</td>
</tr>
<tr>
<th>Status</th>
<td>CONFIRMED
</td>
</tr>
<tr>
<th>Keywords</th>
<td>wrong-debug
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>Scalar Optimizations
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>jeremy.morse.llvm@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>chackz0x12@gmail.com, dblaikie@gmail.com, greg.bedwell@sony.com, international.phantom@gmail.com, llvm-bugs@lists.llvm.org, paul.robinson@am.sony.com
</td>
</tr>
<tr>
<th>Blocks</th>
<td>31268
</td>
</tr></table>
<p>
<div>
<pre>With llvm@r353515, running 'opt -o - -S -adce" over the input IR below, the
dbg.value of %foo is dropped. This occurs even if I put the dbg.value above the
store, or put "arg: 1" in the DILocalVariable. AFAIK there's no reason for ADCE
to drop dbg.values when it doesn't drop any "real" IR instructions, and at the
very least it should leave a 'dbg.value(undef...)' in its place.
-------->8--------
target triple = "x86_64-unknown-linux-gnu"
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
declare void @llvm.dbg.value(metadata, metadata, metadata)
define i32 @test(i32 *%foo) {
store i32 0, i32 *%foo
call void @llvm.dbg.value(metadata i32* %foo, metadata !1, metadata
!DIExpression()), !dbg !6
ret i32 0
}
!llvm.module.flags = !{!4}
!llvm.dbg.cu = !{!2}
!1 = !DILocalVariable(name: "bees", scope: !5, type: !7)
!2 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !3, producer:
"beards", isOptimized: true, runtimeVersion: 4, emissionKind: FullDebug)
!3 = !DIFile(filename: "bees.cpp", directory: "")
!4 = !{i32 2, !"Debug Info Version", i32 3}
!5 = distinct !DISubprogram(name: "nope", scope: !2, file: !3, line: 1, unit:
!2)
!6 = !DILocation(line: 0, scope: !5)
!7 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !8, size: 64)
!8 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
--------8<--------</pre>
</div>
</p>
<div id="referenced">
<hr style="border: 1px dashed #969696">
<b>Referenced Bugs:</b>
<ul>
<li>
[<a class="bz_bug_link
bz_status_CONFIRMED "
title="CONFIRMED - Umbrella: debug info for optimized code"
href="https://bugs.llvm.org/show_bug.cgi?id=31268">Bug 31268</a>] Umbrella: debug info for optimized code
</li>
</ul>
</div>
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