https://bugs.llvm.org/show_bug.cgi?id=41766
Bug ID: 41766
Summary: Clang-trunk Generates Wrong Debug values with -O1
Product: libraries
Version: trunk
Hardware: PC
OS: Linux
Status: NEW
Keywords: wrong-debug
Severity: enhancement
Priority: P
Component: DebugInfo
Assignee: unassignedb...@nondot.org
Reporter: yuanboli...@gmail.com
CC: dav...@freebsd.org, jdevliegh...@apple.com,
keith.wal...@arm.com, llvm-bugs@lists.llvm.org,
paul_robin...@playstation.sony.com
$ 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 (https://llvm.org/svn/llvm-project/lldb/trunk 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.
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