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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 - Clang-trunk Generates Wrong Debug values with -O1"
href="https://bugs.llvm.org/show_bug.cgi?id=41766">41766</a>
</td>
</tr>
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<th>Summary</th>
<td>Clang-trunk Generates Wrong Debug values with -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>davide@freebsd.org, jdevlieghere@apple.com, keith.walker@arm.com, llvm-bugs@lists.llvm.org, paul_robinson@playstation.sony.com
</td>
</tr></table>
<p>
<div>
<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 c = 2, e;
short d;
char(a)(b) {}
int main() {
int p_99;
short f = p_99 = 0 <= 7;
for (; d < 9;) {
optimize_me_not();
{
int g;
if (c)
break;
f &&a(p_99 ^= 1);
}
if (p_99)
e = 0;
}
}
$ cat outer.c
optimize_me_not() {}
$ cat cmds
b 8
r
p p_99
kill
q
$ 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 8
Breakpoint 1: where = a.out`main + 45 at abc.c:8:5, address =
0x00000000004004bd
(lldb) r
Process 21953 stopped
* thread #1, name = 'a.out', stop reason = breakpoint 1.1
frame #0: 0x00000000004004bd a.out`main at abc.c:8:5
5 int p_99;
6 short f = p_99 = 0 <= 7;
7 for (; d < 9;) {
-> 8 optimize_me_not();
9 {
10 int g;
11 if (c)
Process 21953 launched: '/home/ybli/Projects/LLDB-testing/reduce.llvm/a.out'
(x86_64)
(lldb) p p_99
(int) $0 = 1
(lldb) kill
Process 21953 exited with status = 9 (0x00000009)
(lldb) q
$ 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 8
Breakpoint 1: where = a.out`main + 16 at abc.c:8:5, address =
0x00000000004004a0
(lldb) r
Process 27481 stopped
* thread #1, name = 'a.out', stop reason = breakpoint 1.1
frame #0: 0x00000000004004a0 a.out`main at abc.c:8:5
5 int p_99;
6 short f = p_99 = 0 <= 7;
7 for (; d < 9;) {
-> 8 optimize_me_not();
9 {
10 int g;
11 if (c)
Process 27481 launched: '/home/ybli/Projects/LLDB-testing/reduce.llvm/a.out'
(x86_64)
(lldb) p p_99
(int) $0 = 0
(lldb) kill
Process 27481 exited with status = 9 (0x00000009)
(lldb) q
It is worth noting that if we remove the unnecessary '{' and '}' immediate
after "optimize_me_not()" in abc.c, the bug cannot reproduce.</pre>
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