[llvm-bugs] [Bug 45080] New: Wrong debug info generated at -O3 (-O0 is correct)

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=45080

            Bug ID: 45080
           Summary: Wrong debug info generated at -O3 (-O0 is correct)
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: DebugInfo
          Assignee: unassignedbugs at nondot.org
          Reporter: shuo.d at outlook.com
                CC: jdevlieghere at apple.com, keith.walker at arm.com,
                    llvm-bugs at lists.llvm.org,
                    paul_robinson at playstation.sony.com

The expected output from lldb should be 0, but lldb outputs -7 when the program
is compiled with "-O3".



$ clang-trunk -v
clang version 11.0.0 (https://github.com/llvm/llvm-project.git
daab6ad58d4b2c90126efacb836c9286fd85031f)
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/24113/report/a.out'
(x86_64).
(lldb) command source -s 0 'cmds'
Executing commands in '/home/sding/LLDB-testing/reduce/24113/report/cmds'.
(lldb) b 6
Breakpoint 1: where = a.out`main + 5 at abc.c:6:5, address = 0x0000000000400485
(lldb) r
Process 18367 stopped
* thread #1, name = 'a.out', stop reason = breakpoint 1.1
    frame #0: 0x0000000000400485 a.out`main at abc.c:6:5
   3    int main() {
   4      int l_2864 = -7L;
   5      l_2864 = b;
-> 6      a = &l_2864; // optimize_me_not0
   7    }

Process 18367 launched: '/home/sding/LLDB-testing/reduce/24113/report/a.out'
(x86_64)
(lldb) p l_2864 
(int) $0 = -7
(lldb) kill
Process 18367 exited with status = 9 (0x00000009) 
(lldb) q




$ 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/24113/report/a.out'
(x86_64).
(lldb) command source -s 0 'cmds'
Executing commands in '/home/sding/LLDB-testing/reduce/24113/report/cmds'.
(lldb) b 6
Breakpoint 1: where = a.out`main + 24 at abc.c:6:5, address =
0x0000000000400498
(lldb) r
Process 21823 stopped
* thread #1, name = 'a.out', stop reason = breakpoint 1.1
    frame #0: 0x0000000000400498 a.out`main at abc.c:6:5
   3    int main() {
   4      int l_2864 = -7L;
   5      l_2864 = b;
-> 6      a = &l_2864; // optimize_me_not0
   7    }

Process 21823 launched: '/home/sding/LLDB-testing/reduce/24113/report/a.out'
(x86_64)
(lldb) p l_2864 
(int) $0 = 0
(lldb) kill
Process 21823 exited with status = 9 (0x00000009) 
(lldb) q




$ cat abc.c 
int *a;
char b;
int main() {
  int l_2864 = -7L;
  l_2864 = b;
  a = &l_2864; // optimize_me_not0
}




$ cat cmds 
b 6
r
p l_2864 
kill
q

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