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<head>
<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=45095">45095</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Wrong debug info generated at -O3 (-O0 is correct)
</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>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>shuo.d@outlook.com
</td>
</tr>
<tr>
<th>CC</th>
<td>jdevlieghere@apple.com, keith.walker@arm.com, llvm-bugs@lists.llvm.org, paul_robinson@playstation.sony.com
</td>
</tr></table>
<p>
<div>
<pre>The expected output from lldb should be -55, but lldb outputs 7 when the
program is compiled with "-O3".
$ clang-trunk -v
clang version 11.0.0 (<a href="https://github.com/llvm/llvm-project.git">https://github.com/llvm/llvm-project.git</a>
534d8866a1d7e6aa86cdf1d71d30c748f7afe59c)
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
abc.c:11:8: warning: expression result unused [-Wunused-value]
p_44 & 4UL;
~~~~ ^ ~~~
abc.c:12:1: warning: non-void function does not return a value in all control
paths [-Wreturn-type]
}
^
2 warnings generated.
$ lldb-trunk -s cmds -b a.out
(lldb) target create "a.out"
Current executable set to '/home/sding/LLDB-testing/reduce/24545/report/a.out'
(x86_64).
(lldb) command source -s 0 'cmds'
Executing commands in '/home/sding/LLDB-testing/reduce/24545/report/cmds'.
(lldb) b 7
Breakpoint 1: 2 locations.
(lldb) r
Process 7605 stopped
* thread #1, name = 'a.out', stop reason = breakpoint 1.2
frame #0: 0x00000000004004ba a.out`main [inlined] e(p_44=7) at abc.c:7:9
4 unsigned e(p_44) {
5 for (; a <= 9;) {
6 p_44 = d(55);
-> 7 if (c) // optimize_me_not0
8 c ^= 7;
9 return 0;
10 }
Process 7605 launched: '/home/sding/LLDB-testing/reduce/24545/report/a.out'
(x86_64)
(lldb) p p_44
(int) $0 = 7
(lldb) kill
Process 7605 exited with status = 9 (0x00000009)
(lldb) q
$ clang-trunk -g abc.c -O0
abc.c:11:8: warning: expression result unused [-Wunused-value]
p_44 & 4UL;
~~~~ ^ ~~~
abc.c:12:1: warning: non-void function does not return a value in all control
paths [-Wreturn-type]
}
^
2 warnings generated.
$ lldb-trunk -s cmds -b a.out
(lldb) target create "a.out"
Current executable set to '/home/sding/LLDB-testing/reduce/24545/report/a.out'
(x86_64).
(lldb) command source -s 0 'cmds'
Executing commands in '/home/sding/LLDB-testing/reduce/24545/report/cmds'.
(lldb) b 7
Breakpoint 1: where = a.out`e + 44 at abc.c:7:9, address = 0x00000000004004cc
(lldb) r
Process 9725 stopped
* thread #1, name = 'a.out', stop reason = breakpoint 1.1
frame #0: 0x00000000004004cc a.out`e(p_44=-55) at abc.c:7:9
4 unsigned e(p_44) {
5 for (; a <= 9;) {
6 p_44 = d(55);
-> 7 if (c) // optimize_me_not0
8 c ^= 7;
9 return 0;
10 }
Process 9725 launched: '/home/sding/LLDB-testing/reduce/24545/report/a.out'
(x86_64)
(lldb) p p_44
(int) $0 = -55
(lldb) kill
Process 9725 exited with status = 9 (0x00000009)
(lldb) q
$ cat abc.c
short a;
int c;
char(d)(b) { return -b; }
unsigned e(p_44) {
for (; a <= 9;) {
p_44 = d(55);
if (c) // optimize_me_not0
c ^= 7;
return 0;
}
p_44 & 4UL;
}
int main() { e(7); }
$ cat cmds
b 7
r
p p_44
kill
q</pre>
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