[Bug rtl-optimization/57193] [4.9/5/6 Regression] suboptimal register allocation for SSE registers

[law at redhat dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=57193

--- Comment #10 from Jeffrey A. Law  ---
Look in lra-coalesce, if we have code to eliminate those copies, that's where
I'd expect to find it.

[Bug rtl-optimization/57193] [4.9/5/6 Regression] suboptimal register allocation for SSE registers

[bernds at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=57193

Bernd Schmidt  changed:

   What|Removed |Added

 CC||bernds at gcc dot gnu.org

--- Comment #9 from Bernd Schmidt  ---
It looks like the situation is as follows (X is the LRA-created reload reg)

X = a
op on X
b = X

where a and b are different registers already allocated by IRA, hence we can
avoid one copy at most. I'm not very familiar with LRA yet, but I see no code
to rethink such register allocation choices.

-frename-registers gets rid of one unnecessary copy, it was enhanced to detect
such situations for gcc-6. Maybe we should finally enable that for -O2 and
higher?

[Bug rtl-optimization/57193] [4.9/5/6 Regression] suboptimal register allocation for SSE registers

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=57193

Jakub Jelinek jakub at gcc dot gnu.org changed:

   What|Removed |Added

   Target Milestone|4.9.3   |4.9.4

[Bug rtl-optimization/57193] [4.9/5/6 Regression] suboptimal register allocation for SSE registers

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=57193

--- Comment #8 from Jakub Jelinek jakub at gcc dot gnu.org ---
GCC 4.9.3 has been released.