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<head>
<base href="https://bugs.llvm.org/">
</head>
<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=43949">43949</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 0. However, compiled with "-O3", lldb
outputs 5.
$ 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/32221/report/a.out'
(x86_64).
(lldb) command source -s 0 'cmds'
Executing commands in '/home/sding/LLDB-testing/reduce/32221/report/cmds'.
(lldb) b 22
Breakpoint 1: where = a.out`main + 671 at abc.c:22:7, address =
0x00000000004007df
(lldb) r
Process 24738 stopped
* thread #1, name = 'a.out', stop reason = breakpoint 1.1
frame #0: 0x00000000004007df a.out`main at abc.c:22:7
19 h((char)i);
20 i = 0;
21 for (; i < 2; i++) {
-> 22 h(d[i]); // optimize_me_not0
23 }
24 }
Process 24738 launched: '/home/sding/LLDB-testing/reduce/32221/report/a.out'
(x86_64)
(lldb) p i
(int) $0 = 5
$ 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/32221/report/a.out'
(x86_64).
(lldb) command source -s 0 'cmds'
Executing commands in '/home/sding/LLDB-testing/reduce/32221/report/cmds'.
(lldb) b 22
Breakpoint 1: where = a.out`main + 104 at abc.c:22:7, address =
0x00000000004005c8
(lldb) r
Process 30349 stopped
* thread #1, name = 'a.out', stop reason = breakpoint 1.1
frame #0: 0x00000000004005c8 a.out`main at abc.c:22:7
19 h((char)i);
20 i = 0;
21 for (; i < 2; i++) {
-> 22 h(d[i]); // optimize_me_not0
23 }
24 }
Process 30349 launched: '/home/sding/LLDB-testing/reduce/32221/report/a.out'
(x86_64)
(lldb) p i
(int) $0 = 0
$ cat abc.c
int a[256];
int b, c;
static int d[] = {0, -4L};
void e(f) { b = b & 4095 ^ a[(b ^ f) & 5]; }
void h(f) {
unsigned long g = f;
b = b & 4095 ^ a[(b ^ g) & 255];
e(g >> 8);
e(g >> 6);
e(g >> 4);
e(g >> 2);
e(g >> 56);
}
int main() {
int i = 0;
if (c)
d[1] = 3;
for (; i < 5; i++)
h((char)i);
i = 0;
for (; i < 2; i++) {
h(d[i]); // optimize_me_not0
}
}
$ cat cmds
b 22
r
p i
kill
q</pre>
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