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<base href="https://bugs.llvm.org/">
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<body><table border="1" cellspacing="0" cellpadding="8">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Debug info for induction variable points at next iteration's value"
href="https://bugs.llvm.org/show_bug.cgi?id=35113">35113</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Debug info for induction variable points at next iteration's value
</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>All
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>enhancement
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>DebugInfo
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>aprantl@apple.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>void bar(float);
void f(float *input, long long n, long long s) {
for (long long i = 0; i < n; i+=s )
bar(input[i]);
}
clang -g -O1 -S -emit-llvm /tmp/loop.c -o -
...
for.body: ; preds =
%for.body.preheader, %for.body
%i.05 = phi i64 [ %add, %for.body ], [ 0, %for.body.preheader ]
tail call void @llvm.dbg.value(metadata i64 %i.05, metadata !18, metadata
!DIExpression()), !dbg !23
%arrayidx = getelementptr inbounds float, float* %input, i64 %i.05, !dbg !27
%0 = load float, float* %arrayidx, align 4, !dbg !27, !tbaa !29
tail call void @bar(float %0) #3, !dbg !33
%add = add nsw i64 %i.05, %s, !dbg !34
tail call void @llvm.dbg.value(metadata i64 %add, metadata !18, metadata
!DIExpression()), !dbg !23
tail call void @llvm.dbg.value(metadata i64 %add, metadata !18, metadata
!DIExpression()), !dbg !23
%cmp = icmp slt i64 %add, %n, !dbg !24
br i1 %cmp, label %for.body, label %for.cond.cleanup, !dbg !26, !llvm.loop
!35
}
!7 = !{!"clang version 6.0.0 (trunk 316686) (llvm/trunk 316682)"}
!23 = !DILocation(line: 3, column: 18, scope: !19)
!34 = !DILocation(line: 3, column: 32, scope: !25)
There are two problems here:
1. The dbg.value describing %add is duplicated.
2. It is wrong. If we insert a dbg.value for %add I would either expect it to
have a DIExpression that subtracts %s (which we can't represent), *or* to have
a DILocation that clearly points to a source location after the increment.</pre>
</div>
</p>
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