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From: "yangyibiao at hust dot edu.cn" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug debug/95360] inconsistent behaviors at -O0
Date: Wed, 27 May 2020 13:25:50 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D95360

--- Comment #5 from Yibiao Yang <yangyibiao at hust dot edu.cn> ---
(In reply to Tom de Vries from comment #3)
> (In reply to Yibiao Yang from comment #0)
> > Breakpoint 1, main () at small.c:5
> > 5	  for (; d<1; d++)
> > (gdb) stepi
> > 0x0000000000401154	5	  for (; d<1; d++)
> > (gdb) stepi
> > 0x000000000040115a	5	  for (; d<1; d++)
> > (gdb) stepi
> > 0x000000000040115c	5	  for (; d<1; d++)
> > (gdb) stepi
> > 0x000000000040113b	6	    for (; b<1; b++)
> > (gdb) stepi
> > 0x0000000000401141	6	    for (; b<1; b++)
> > (gdb) stepi
> > 0x0000000000401143	6	    for (; b<1; b++)
> > (gdb) stepi
> > 7	      c[b][d+1] =3D 0;
> > (gdb)
> >=20
> >=20
> > /*****************************************************
> > As showed, Line 6 is hit first and then hit Line 7 with stepi.
> > However, when using step, gdb is first hit Line 7 and then hit Line 6.
> > This is an inconsistent behaviors between stepi and step
> > *****************************************************/
>=20
> Gdb is behaving consistently in the following sense:
> - when gdb is at a "recommended breakpoint location" it shows the source =
line
>   only with line number prefix.
> - otherwise, it shows the source line with both address and line number
> prefix.
>=20
> So, what the stepi sequence shows it that the next "recommended breakpoint
> location" after line 5 is line 7, which is consistent with a step from li=
ne
> 5 to line 7.

I agree that at some time it will step to line 7 after executing line 6  an=
d at
other times it will step to line 6 after executing line7  as they both at t=
he
same iteration.=20

However, my concern is that for the "first iteration or first time" line 6
should be hit ahead of line 7 no matter on whether we using step or using
stepi. That's to say, the first hit of Line 6 or Line 7 should be consistent
between step and stepi.=