https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92549
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |ASSIGNED
Assignee|unassigned at gcc dot gnu.org |jakub at gcc dot gnu.org
--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 47292
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=47292&action=edit
gcc10-pr92549.patch
Yeah, there are *swap<mode> patterns, but they are unlikely to trigger, because
before RA usually there is no swap between pseudos, but simply different
pseudos, and only during RA we get to a need of a swap.
This patch handles it in peephole2. The big question is if it should be done
always (as in the patch), or only at -Os or on selected modern CPUs + maybe
generic tuning, where xchg with register operands just uses normal register
renaming and is 0.5 or worst case 1 cycles.
