public inbox for gcc-bugs@sourceware.org
help / color / mirror / Atom feed
* [Bug debug/112565] New: Abnormal Jump in Execution using 'stepi' Command in GDB under O2 optimization
@ 2023-11-16 11:51 iamanonymous.cs at gmail dot com
2023-11-16 11:55 ` [Bug debug/112565] " vries at gcc dot gnu.org
` (4 more replies)
0 siblings, 5 replies; 6+ messages in thread
From: iamanonymous.cs at gmail dot com @ 2023-11-16 11:51 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112565
Bug ID: 112565
Summary: Abnormal Jump in Execution using 'stepi' Command in
GDB under O2 optimization
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: debug
Assignee: unassigned at gcc dot gnu.org
Reporter: iamanonymous.cs at gmail dot com
Target Milestone: ---
Bug reported initially reported:
https://sourceware.org/bugzilla/show_bug.cgi?id=31070
Tom de Vries suggests that this issue may be attributed to a GCC optimization
bug.
$ cat small.c
int glob_int_arr[100];
int *glob_ptr_int = glob_int_arr;
void simple_global ()
{
__builtin_prefetch (glob_int_arr, 0, 0);
__builtin_prefetch (glob_ptr_int, 0, 0);
}
int main()
{
simple_global ();
exit (0);
}
$ gcc -w -O2 -g small.c; gdb -q a.out
Reading symbols from a.out...
(gdb) b main
Breakpoint 1 at 0x401040: file small.c, line 6.
(gdb) r
Starting program: /root/devil/a.out
Breakpoint 1, main () at small.c:6
6 __builtin_prefetch (glob_int_arr, 0, 0);
(gdb) si
0x0000000000401044 in simple_global () at small.c:7
7 __builtin_prefetch (glob_ptr_int, 0, 0);
(gdb) si
0x000000000040104b in main () at small.c:13
13 exit (0);
(gdb) si
0x000000000040104d in simple_global () at small.c:6
6 __builtin_prefetch (glob_int_arr, 0, 0);
(gdb)
=================================================
When using the 'stepi' command in GDB, an abnormal jump in the execution occurs
when reaching line 7 of the code. The execution unexpectedly jumps to line 13.
$ gcc --version
gcc (GCC) 14.0.0 20231116 (experimental)
Copyright (C) 2023 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.
$ gdb --version
GNU gdb (GDB) 15.0.50.20231116-git
Copyright (C) 2023 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.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug debug/112565] Abnormal Jump in Execution using 'stepi' Command in GDB under O2 optimization
2023-11-16 11:51 [Bug debug/112565] New: Abnormal Jump in Execution using 'stepi' Command in GDB under O2 optimization iamanonymous.cs at gmail dot com
@ 2023-11-16 11:55 ` vries at gcc dot gnu.org
2023-11-16 12:00 ` iamanonymous.cs at gmail dot com
` (3 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: vries at gcc dot gnu.org @ 2023-11-16 11:55 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112565
--- Comment #1 from Tom de Vries <vries at gcc dot gnu.org> ---
(In reply to Anonymous from comment #0)
> Tom de Vries suggests that this issue may be attributed to a GCC
> optimization bug.
I do not.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug debug/112565] Abnormal Jump in Execution using 'stepi' Command in GDB under O2 optimization
2023-11-16 11:51 [Bug debug/112565] New: Abnormal Jump in Execution using 'stepi' Command in GDB under O2 optimization iamanonymous.cs at gmail dot com
2023-11-16 11:55 ` [Bug debug/112565] " vries at gcc dot gnu.org
@ 2023-11-16 12:00 ` iamanonymous.cs at gmail dot com
2023-11-16 12:42 ` iamanonymous.cs at gmail dot com
` (2 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: iamanonymous.cs at gmail dot com @ 2023-11-16 12:00 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112565
--- Comment #2 from Anonymous <iamanonymous.cs at gmail dot com> ---
(In reply to Tom de Vries from comment #1)
> (In reply to Anonymous from comment #0)
> > Tom de Vries suggests that this issue may be attributed to a GCC
> > optimization bug.
>
> I do not.
Thanks for the correction. I apologize for the misunderstanding. I didn't
notice that you mentioned this behavior was expected.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug debug/112565] Abnormal Jump in Execution using 'stepi' Command in GDB under O2 optimization
2023-11-16 11:51 [Bug debug/112565] New: Abnormal Jump in Execution using 'stepi' Command in GDB under O2 optimization iamanonymous.cs at gmail dot com
2023-11-16 11:55 ` [Bug debug/112565] " vries at gcc dot gnu.org
2023-11-16 12:00 ` iamanonymous.cs at gmail dot com
@ 2023-11-16 12:42 ` iamanonymous.cs at gmail dot com
2023-11-16 12:47 ` rguenth at gcc dot gnu.org
2023-11-16 14:26 ` iamanonymous.cs at gmail dot com
4 siblings, 0 replies; 6+ messages in thread
From: iamanonymous.cs at gmail dot com @ 2023-11-16 12:42 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112565
--- Comment #3 from Anonymous <iamanonymous.cs at gmail dot com> ---
However, I still feel that the current debugging process be somewhat
misleading, and I am uncertain if there are any approaches to enhance the
overall debugging experience.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug debug/112565] Abnormal Jump in Execution using 'stepi' Command in GDB under O2 optimization
2023-11-16 11:51 [Bug debug/112565] New: Abnormal Jump in Execution using 'stepi' Command in GDB under O2 optimization iamanonymous.cs at gmail dot com
` (2 preceding siblings ...)
2023-11-16 12:42 ` iamanonymous.cs at gmail dot com
@ 2023-11-16 12:47 ` rguenth at gcc dot gnu.org
2023-11-16 14:26 ` iamanonymous.cs at gmail dot com
4 siblings, 0 replies; 6+ messages in thread
From: rguenth at gcc dot gnu.org @ 2023-11-16 12:47 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112565
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |INVALID
Status|UNCONFIRMED |RESOLVED
--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
GCC can interleave instructions belonging to different source lines so that's
what you see. Since you advance assembler instructions I don't see a way to
"improve" things here when optimizing.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug debug/112565] Abnormal Jump in Execution using 'stepi' Command in GDB under O2 optimization
2023-11-16 11:51 [Bug debug/112565] New: Abnormal Jump in Execution using 'stepi' Command in GDB under O2 optimization iamanonymous.cs at gmail dot com
` (3 preceding siblings ...)
2023-11-16 12:47 ` rguenth at gcc dot gnu.org
@ 2023-11-16 14:26 ` iamanonymous.cs at gmail dot com
4 siblings, 0 replies; 6+ messages in thread
From: iamanonymous.cs at gmail dot com @ 2023-11-16 14:26 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112565
--- Comment #5 from Anonymous <iamanonymous.cs at gmail dot com> ---
(In reply to Richard Biener from comment #4)
> GCC can interleave instructions belonging to different source lines so
> that's what you see. Since you advance assembler instructions I don't see a
> way to
> "improve" things here when optimizing.
Got it. Thanks.
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2023-11-16 14:26 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2023-11-16 11:51 [Bug debug/112565] New: Abnormal Jump in Execution using 'stepi' Command in GDB under O2 optimization iamanonymous.cs at gmail dot com
2023-11-16 11:55 ` [Bug debug/112565] " vries at gcc dot gnu.org
2023-11-16 12:00 ` iamanonymous.cs at gmail dot com
2023-11-16 12:42 ` iamanonymous.cs at gmail dot com
2023-11-16 12:47 ` rguenth at gcc dot gnu.org
2023-11-16 14:26 ` iamanonymous.cs at gmail dot com
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).