This is the mail archive of the
gcc-bugs@gcc.gnu.org
mailing list for the GCC project.
c/8221: return value of a function is forgotten
- From: c dot kaliszyk at zodiac dot mimuw dot edu dot pl
- To: gcc-gnats at gcc dot gnu dot org
- Cc: cek at wp dot pl
- Date: 14 Oct 2002 08:44:09 -0000
- Subject: c/8221: return value of a function is forgotten
- Reply-to: c dot kaliszyk at zodiac dot mimuw dot edu dot pl
>Number: 8221
>Category: c
>Synopsis: return value of a function is forgotten
>Confidential: no
>Severity: serious
>Priority: medium
>Responsible: unassigned
>State: open
>Class: wrong-code
>Submitter-Id: net
>Arrival-Date: Mon Oct 14 01:46:00 PDT 2002
>Closed-Date:
>Last-Modified:
>Originator: c.kaliszyk@zodiac.mimuw.edu.pl
>Release: 3.2
>Organization:
>Environment:
Linux orka 2.5.40 #1 Thu Oct 3 07:30:38 CEST 2002 i686 unknown
configured with: /home/c/tmp/gcc-3.2/configure --prefix=3D/usr --enable-thr=
eads
>Description:
I tried to measure time twice, and substract these results.
When the function is inlined both results are stored in %ecx and after that
%ecx is substracted from itself, and I get zero.
Without inlining it works correct.
>How-To-Repeat:
I call "gcc -O2" on this:
--cut--
inline int getcputime(void) {
int i;
__asm__(
"rdtsc
movl %%eax, %0"
: :"g" (i) :"ax", "dx");
return i;
}
int main(void) {
int x =3D getcputime();
int y =3D getcputime();
printf ("Time measure resolution: %i\n", y - x);
return 0;
}
--cut--
>Fix:
Remove "inline" before the function definition or call gcc without -O
If the function is not inlined the return values of both calls are stored on
the stack in diffrent places and correctly substracted.
>Release-Note:
>Audit-Trail:
>Unformatted: