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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 - Clang-trunk produce incorrect debug info under O1"
href="https://bugs.llvm.org/show_bug.cgi?id=42170">42170</a>
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<th>Summary</th>
<td>Clang-trunk produce incorrect debug info under O1
</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>NEW
</td>
</tr>
<tr>
<th>Keywords</th>
<td>wrong-debug
</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>yuanboli233@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>aprantl@apple.com, davide@freebsd.org, jdevlieghere@apple.com, keith.walker@arm.com, llvm-bugs@lists.llvm.org, paul_robinson@playstation.sony.com, vsk@apple.com
</td>
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<pre>$ clang-trunk --version
clang version 9.0.0 (trunk 355785)
Target: x86_64-unknown-linux-gnu
Thread model: posix
$ lldb-trunk --version
lldb version 9.0.0 (<a href="https://llvm.org/svn/llvm-project/lldb/trunk">https://llvm.org/svn/llvm-project/lldb/trunk</a> revision
355785)
clang revision 355785
llvm revision 355785
$ cat abc.c
int b;
short(a)(c) { return c; }
int main() {
short d;
int e, p_40 = 0;
e = b + 1;
d = 26900 + e;
p_40 = d;
optimize_me_not();
a(p_40);
}
$ cat outer.c
optimize_me_not() {}
$ cat cmds
b 9
r
p p_40
kill
q
The debug info is correct under O0:
$ clang-trunk abc.c outer.c -O0 -g
$ lldb-trunk -s cmds -b a.out
(lldb) target create "a.out"
Current executable set to 'a.out' (x86_64).
(lldb) command source -s 0 'cmds'
Executing commands in '/home/ybli/Projects/LLDB-testing/reduce.llvm/cmds'.
(lldb) b 9
Breakpoint 1: where = a.out`main + 50 at abc.c:9:3, address =
0x00000000004004c2
(lldb) r
Process 27402 stopped
* thread #1, name = 'a.out', stop reason = breakpoint 1.1
frame #0: 0x00000000004004c2 a.out`main at abc.c:9:3
6 e = b + 1;
7 d = 26900 + e;
8 p_40 = d;
-> 9 optimize_me_not();
10 a(p_40);
11 }
Process 27402 launched: '/home/ybli/Projects/LLDB-testing/reduce.llvm/a.out'
(x86_64)
(lldb) p p_40
(int) $0 = 26901
(lldb) kill
Process 27402 exited with status = 9 (0x00000009)
(lldb) q
Under O1 the debug info is not correct:
$ clang-trunk abc.c outer.c -O1 -g
$ lldb-trunk -s cmds -b a.out
(lldb) target create "a.out"
Current executable set to 'a.out' (x86_64).
(lldb) command source -s 0 'cmds'
Executing commands in '/home/ybli/Projects/LLDB-testing/reduce.llvm/cmds'.
(lldb) b 9
Breakpoint 1: where = a.out`main + 1 at abc.c:9:3, address = 0x0000000000400491
(lldb) r
Process 9582 stopped
* thread #1, name = 'a.out', stop reason = breakpoint 1.1
frame #0: 0x0000000000400491 a.out`main at abc.c:9:3
6 e = b + 1;
7 d = 26900 + e;
8 p_40 = d;
-> 9 optimize_me_not();
10 a(p_40);
11 }
Process 9582 launched: '/home/ybli/Projects/LLDB-testing/reduce.llvm/a.out'
(x86_64)
(lldb) p p_40
(int) $0 = 0
(lldb) kill
Process 9582 exited with status = 9 (0x00000009)
(lldb) q
Bisection suggest it is possibly related to "Deduce function attributes on SCC"
produce correct results:
BISECT: running pass (18) Remove unused exception handling info on SCC (a)
BISECT: NOT running pass (19) Deduce function attributes on SCC (a)
produce inccorect results:
BISECT: running pass (18) Remove unused exception handling info on SCC (a)
BISECT: running pass (19) Deduce function attributes on SCC (a)</pre>
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