[Bug debug/95414] New: Wrong debug info for argc at -O2

[Bug debug/95414] New: Wrong debug info for argc at -O2

[yangyibiao at hust dot edu.cn]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95414

            Bug ID: 95414
           Summary: Wrong debug info for argc at -O2
           Product: gcc
           Version: 10.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: debug
          Assignee: unassigned at gcc dot gnu.org
          Reporter: yangyibiao at hust dot edu.cn
  Target Milestone: ---

Created attachment 48633
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=48633&action=edit
a.out

$ gcc --version
gcc (GCC) 10.0.1 20200419 (experimental)
Copyright (C) 2020 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

yibiao:~/Debugger$ gdb --version
GNU gdb (GDB) 10.0.50.20200517-git
Copyright (C) 2020 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.


Consider test-case:
...
$ cat small.c
#include <stdio.h>

int main(int argc, char **argv) {
  char buf[6];
  char c[] = "abc";
  sprintf(buf, (char *)c, 1);

  return 0;
}
...

$ gcc -O2 -g small.c; gdb -q a.out
Reading symbols from a.out...
(gdb) b main
Breakpoint 1 at 0x401040: file small.c, line 5.
(gdb) r
Starting program: /home/yibiao/Debugger/a.out 

Breakpoint 1, main (argc=1, argv=0x7fffffffdff8) at small.c:5
5         char c[] = "abc";
(gdb) info args argc
argc = 1
(gdb) step
6         sprintf(buf, (char *)c, 1);
(gdb) info args argc
argc = -8454
(gdb) 


/**************************************
We can find that at line 5, the value of argc is 1. When stepping to line 6,
the value of argc is changed to -8454. When stepping with stepi, the value of
argc is correct.

[Bug debug/95414] Wrong debug info for argc at -O2

[yangyibiao at nju dot edu.cn]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95414

--- Comment #1 from Yibiao Yang <yangyibiao at nju dot edu.cn> ---
Hi, @Richard Biener

I updated gcc to the latest trunk version and found that this bug seems have
been fixed in the following trunk version.

$ gcc --version
gcc (GCC) 13.0.0 20221107 (experimental)

I was wondering whether this bug can be closed as fixed.

[Bug debug/95414] Wrong debug info for argc at -O2

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95414

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|UNCONFIRMED                 |RESOLVED
      Known to fail|                            |10.3.0, 11.2.0
      Known to work|                            |10.4.0, 11.3.0, 12.1.0

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
Even GCC 10.4.0 now prints <optimized out>, so fixed (possibly a dup).