On Sun, Dec 1, 2019 at 6:55 PM Jakub Jelinek wrote:
>
> On Sun, Dec 01, 2019 at 03:43:37PM +0100, Jan Hubicka wrote:
> > > PR target/92549
> > > * config/i386/i386.md (peephole2 for *swap): New peephole2.
> > >
> > > * gcc.target/i386/pr92549.c: New test.
> >
> > It is very hard to ge
On Sun, Dec 01, 2019 at 03:43:37PM +0100, Jan Hubicka wrote:
> > PR target/92549
> > * config/i386/i386.md (peephole2 for *swap): New peephole2.
> >
> > * gcc.target/i386/pr92549.c: New test.
>
> It is very hard to get a testcase, unforutnately, but I got the
> following (locally non
> Hi!
>
> xchg instruction is smaller, in some cases much smaller than 3 moves,
> (e.g. in the testcase 2 bytes vs. 8 bytes), and is not a performance
> disaster, but from Agner Fog tables and
> https://stackoverflow.com/questions/45766444/why-is-xchg-reg-reg-a-3-micro-op-instruction-on-modern-int
On 11/19/19 4:19 AM, Richard Biener wrote:
On Tue, Nov 19, 2019 at 10:04 AM Jakub Jelinek wrote:
Hi!
xchg instruction is smaller, in some cases much smaller than 3 moves,
(e.g. in the testcase 2 bytes vs. 8 bytes), and is not a performance
disaster, but from Agner Fog tables and
https://stacko
> Hi!
>
> xchg instruction is smaller, in some cases much smaller than 3 moves,
> (e.g. in the testcase 2 bytes vs. 8 bytes), and is not a performance
> disaster, but from Agner Fog tables and
> https://stackoverflow.com/questions/45766444/why-is-xchg-reg-reg-a-3-micro-op-instruction-on-modern-int
On Tue, Nov 19, 2019 at 10:04 AM Jakub Jelinek wrote:
>
> Hi!
>
> xchg instruction is smaller, in some cases much smaller than 3 moves,
> (e.g. in the testcase 2 bytes vs. 8 bytes), and is not a performance
> disaster, but from Agner Fog tables and
> https://stackoverflow.com/questions/45766444/wh
On Tue, Nov 19, 2019 at 10:04 AM Jakub Jelinek wrote:
>
> Hi!
>
> xchg instruction is smaller, in some cases much smaller than 3 moves,
> (e.g. in the testcase 2 bytes vs. 8 bytes), and is not a performance
> disaster, but from Agner Fog tables and
> https://stackoverflow.com/questions/45766444/wh
Hi!
xchg instruction is smaller, in some cases much smaller than 3 moves,
(e.g. in the testcase 2 bytes vs. 8 bytes), and is not a performance
disaster, but from Agner Fog tables and
https://stackoverflow.com/questions/45766444/why-is-xchg-reg-reg-a-3-micro-op-instruction-on-modern-intel-architect
