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<base href="https://bugs.llvm.org/">
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<body><table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Wrong debug info generated at -O3 (-O0 is correct)"
href="https://bugs.llvm.org/show_bug.cgi?id=43957">43957</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Wrong debug info generated at -O3 (-O0 is correct)
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</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>Severity</th>
<td>enhancement
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>LLVM Codegen
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>shuo.d@outlook.com
</td>
</tr>
<tr>
<th>CC</th>
<td>davide@freebsd.org, llvm-bugs@lists.llvm.org, neeilans@live.com, richard-llvm@metafoo.co.uk
</td>
</tr></table>
<p>
<div>
<pre>The expected output from lldb should be 36902. However, compiled with "-O3",
lldb outputs 36901.
$ clang-trunk -v
clang version 10.0.0 (trunk 375507)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /usr/local/bin
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/8
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/9
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4.7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6.4
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8.5
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5.5.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/6
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/6.5.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7.4.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/8
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/9
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/9
Candidate multilib: .;@m64
Candidate multilib: 32;@m32
Candidate multilib: x32;@mx32
Selected multilib: .;@m64
$ clang-trunk -g abc.c -O3
$ lldb-trunk -s cmds -b a.out
(lldb) target create "a.out"
Current executable set to '/home/sding/LLDB-testing/reduce/30986/report/a.out'
(x86_64).
(lldb) command source -s 0 'cmds'
Executing commands in '/home/sding/LLDB-testing/reduce/30986/report/cmds'.
(lldb) b 6
Breakpoint 1: where = a.out`main + 10 at abc.c:6:7, address =
0x000000000040048a
(lldb) r
Process 10166 stopped
* thread #1, name = 'a.out', stop reason = breakpoint 1.1
frame #0: 0x000000000040048a a.out`main at abc.c:6:7
3 --b;
4 unsigned l_801 = 36901;
5 ++l_801;
-> 6 if (a) // optimize_me_not0
7 b = 0;
8 }
Process 10166 launched: '/home/sding/LLDB-testing/reduce/30986/report/a.out'
(x86_64)
(lldb) p l_801
(unsigned int) $0 = 36901
(lldb) kill
Process 10166 exited with status = 9 (0x00000009)
(lldb) q
$ clang-trunk -g abc.c -O0
$ lldb-trunk -s cmds -b a.out
(lldb) target create "a.out"
Current executable set to '/home/sding/LLDB-testing/reduce/30986/report/a.out'
(x86_64).
(lldb) command source -s 0 'cmds'
Executing commands in '/home/sding/LLDB-testing/reduce/30986/report/cmds'.
(lldb) b 6
Breakpoint 1: where = a.out`main + 43 at abc.c:6:7, address =
0x00000000004004ab
(lldb) r
Process 18492 stopped
* thread #1, name = 'a.out', stop reason = breakpoint 1.1
frame #0: 0x00000000004004ab a.out`main at abc.c:6:7
3 --b;
4 unsigned l_801 = 36901;
5 ++l_801;
-> 6 if (a) // optimize_me_not0
7 b = 0;
8 }
Process 18492 launched: '/home/sding/LLDB-testing/reduce/30986/report/a.out'
(x86_64)
(lldb) p l_801
(unsigned int) $0 = 36902
(lldb) kill
Process 18492 exited with status = 9 (0x00000009)
(lldb) q
$ cat abc.c
char a, b;
int main() {
--b;
unsigned l_801 = 36901;
++l_801;
if (a) // optimize_me_not0
b = 0;
}
$ cat cmds
b 6
r
p l_801
kill
q</pre>
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