https://bugs.llvm.org/show_bug.cgi?id=41534
Bug ID: 41534
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
This also affects trunk -O2 and -O3
$ 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 a;
int *b;
int main() {
int l_1081 = 1834104526;
int *c = &l_1081;
b = c;
*b = a = 9;
optimize_me_not();
}
$ cat outer.c
optimize_me_not() {}
$ cat cmds
b 8
r
p l_1081
kill
q
$ clang-trunk -O0 -g abc.c outer.c
$ 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 + 60 at abc.c:8:3, address =
0x00000000004004bc
(lldb) r
Process 7408 stopped
* thread #1, name = 'a.out', stop reason = breakpoint 1.1
frame #0: 0x00000000004004bc a.out`main at abc.c:8:3
5 int *c = &l_1081;
6 b = c;
7 *b = a = 9;
-> 8 optimize_me_not();
9 }
Process 7408 launched: '/home/ybli/Projects/LLDB-testing/reduce.llvm/a.out'
(x86_64)
(lldb) p l_1081
(int) $0 = 9
(lldb) kill
Process 7408 exited with status = 9 (0x00000009)
(lldb) q
$ clang-trunk -O1 -g abc.c outer.c
$ 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 + 31 at abc.c:8:3, address =
0x000000000040049f
(lldb) r
Process 13547 stopped
* thread #1, name = 'a.out', stop reason = breakpoint 1.1
frame #0: 0x000000000040049f a.out`main at abc.c:8:3
5 int *c = &l_1081;
6 b = c;
7 *b = a = 9;
-> 8 optimize_me_not();
9 }
Process 13547 launched: '/home/ybli/Projects/LLDB-testing/reduce.llvm/a.out'
(x86_64)
(lldb) p l_1081
(int) $0 = 1834104526
(lldb) kill
Process 13547 exited with status = 9 (0x00000009)
(lldb) q
bisection suggest instcombine:
working:
BISECT: running pass (9) Dead Argument Elimination on module (abc.c)
BISECT: NOT running pass (10) Combine redundant instructions on function (main)
not working:
BISECT: running pass (10) Combine redundant instructions on function (main)
BISECT: NOT running pass (11) Simplify the CFG on function (main)
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