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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 - [DAGCombiner] SDDbgValue is set as invalid by tryToFoldExtOfLoad()"
href="https://bugs.llvm.org/show_bug.cgi?id=52373">52373</a>
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<th>Summary</th>
<td>[DAGCombiner] SDDbgValue is set as invalid by tryToFoldExtOfLoad()
</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>
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<th>OS</th>
<td>Linux
</td>
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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
</td>
</tr>
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<th>Component</th>
<td>Common Code Generator Code
</td>
</tr>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>paulsson@linux.vnet.ibm.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
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<div>
<pre>Created <span class=""><a href="attachment.cgi?id=25409" name="attach_25409" title="reduced testcase">attachment 25409</a> <a href="attachment.cgi?id=25409&action=edit" title="reduced testcase">[details]</a></span>
reduced testcase
This reduced function has an i32 argument passed to a called function:
define void @fun1(i1 %u) #0 !dbg !4 {
entry:
%0 = load i32, i32* @t, align 4
tail call void @llvm.dbg.value(metadata i32 %0, metadata !10, metadata
!DIExpression()), !dbg !17
tail call void @_Z1fi(i32 %0)
unreachable
}
llc -mtriple=s390x-linux-gnu -O0 tc_dbgval.ll -o - |& grep DEBUG
#DEBUG_VALUE: s <- $r2l
If that argument is signextended, the debug value is invalidated ("removed"):
llc -mtriple=s390x-linux-gnu -O0 tc_dbgval_arg_signext.ll -o - |& grep DEBUG
#DEBUG_VALUE: s <- undef
diff tc_dbgval.ll tc_dbgval_arg_signext.ll
13c13
< tail call void @_Z1fi(i32 %0)
---
<span class="quote">> tail call void @_Z1fi(i32 signext %0)</span >
tryToFoldExtOfLoad() calls DAG.ReplaceAllUsesOfValueWith(), which calls
transferDbgValues(), but this is not working properly. When the original load
is deleted, the DbgValue is invalidated.</pre>
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