[llvm-bugs] [Bug 45971] New: Wrong line information at Og

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=45971

            Bug ID: 45971
           Summary: Wrong line information at Og
           Product: clang
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Keywords: wrong-debug
          Severity: enhancement
          Priority: P
         Component: -New Bugs
          Assignee: unassignedclangbugs at nondot.org
          Reporter: massarelli at diag.uniroma1.it
                CC: ditaliano at apple.com, htmldeveloper at gmail.com,
                    llvm-bugs at lists.llvm.org, neeilans at live.com,
                    richard-llvm at metafoo.co.uk

Line 8 should not be hit during debugging.

$ cat a.c
char a, b;
int g_37[] = {1};
int c;
char(d)() { return a; }
void e() {
  if (g_37[0])
    return;
  --b &&d() || c;
}
int main() { e(); }

$ clang -v
clang version 11.0.0 (https://github.com/llvm/llvm-project.git
709c52b9553f4ba83ab901a873392f8a7f2c56a5)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /usr/local/bin
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7.5.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/8
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7.5.0
Candidate multilib: .;@m64
Selected multilib: .;@m64


$ lldb -v
lldb version 11.0.0
  clang revision 709c52b9553f4ba83ab901a873392f8a7f2c56a5
  llvm revision 709c52b9553f4ba83ab901a873392f8a7f2c56a5

$ gdb -v
GNU gdb (Ubuntu 8.1-0ubuntu3.2) 8.1.0.20180409-git

$ clang -Og -g -o opt a.c

$ lldb opt
(lldb) target create "opt"
Current executable set to 'opt' (x86_64).
(lldb) b main
Breakpoint 1: where = opt`main + 1 at a.c:10:14, address = 0x00000000004004b1
(lldb) r
Process 231 launched: '/home/stepping/output/opt' (x86_64)
Process 231 stopped
* thread #1, name = 'opt', stop reason = breakpoint 1.1
    frame #0: 0x00000000004004b1 opt`main at a.c:10:14
   7        return;
   8      --b &&d() || c;
   9    }
-> 10   int main() { e(); }
(lldb) s
Process 231 stopped
* thread #1, name = 'opt', stop reason = step in
    frame #0: 0x0000000000400490 opt`e at a.c:6:7
   3    int c;
   4    char(d)() { return a; }
   5    void e() {
-> 6      if (g_37[0])
   7        return;
   8      --b &&d() || c;
   9    }
(lldb) s
Process 231 stopped
* thread #1, name = 'opt', stop reason = step in
    frame #0: 0x0000000000400499 opt`e at a.c:8:13
   5    void e() {
   6      if (g_37[0])
   7        return;
-> 8      --b &&d() || c;
   9    }
   10   int main() { e(); }
(lldb) di
opt`e:
    0x400490 <+0>:  cmpl   $0x0, 0x200b91(%rip)      ; __dso_handle + 7
    0x400497 <+7>:  je     0x40049a                  ; <+10> at a.c:8:3
->  0x400499 <+9>:  retq   
    0x40049a <+10>: addb   $-0x1, 0x200b90(%rip)     ; opt.PT_LOAD[1]..bss + 4
    0x4004a1 <+17>: retq   

$  gdb opt
(gdb) b main
Breakpoint 1 at 0x4004b1: file a.c, line 10.
(gdb) r
Starting program: opt 

Breakpoint 1, main () at a.c:10
10      int main() { e(); }
(gdb) s
e () at a.c:6
6         if (g_37[0])
(gdb) s
e () at a.c:8
8         --b &&d() || c;
(gdb) s
0x00007ffff7a05b97 in __libc_start_main () from /lib/x86_64-linux-gnu/libc.so.6
(gdb)

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