On Mon, Nov 12, 2007 at 11:07:55PM +0100, Bernd Schmidt wrote:
> Adrian Bunk wrote:
> > It can be a performance regression, but there are also cases where it
> > can improve performance. If gcc produces lower performance code that
> > would be a bug in gcc that should be reported, but using a division is
> > not generally wrong.
> >
> > A more clearer example might be:
> >
> > <-- snip -->
> >
> > void foo(u64 ns)
> > {
> > if (ns < 10000)
> > return;
> >
> > while(ns >= 3) {
> > ns -= 3;
> > #ifdef DEBUG
> > bar(ns);
> > #endif
> > }
> > }
> >
> > <-- snip -->
> >
> > With DEBUG not defined you can hardly argue gcc should be fixed to not
> > use a division for performance reasons.
>
> Absent any clear information about the possible values of ns,
>...
In this example, there is clear information about the possible values
of ns...
> Bernd
cu
Adrian
--
"Is there not promise of rain?" Ling Tan asked suddenly out
of the darkness. There had been need of rain for many days.
"Only a promise," Lao Er said.
Pearl S. Buck - Dragon Seed
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
