[Bug middle-end/55623] [ARM] GCC should not prefer long dependency chains, they inhibit performance on superscalar processors
pinskia at gcc dot gnu.org
gcc-bugzilla@gcc.gnu.org
Sun Dec 9 10:48:00 GMT 2012
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55623
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target| |arm*-*-*, aarch64-*-*
Status|UNCONFIRMED |NEW
Keywords| |missed-optimization
Last reconfirmed| |2012-12-09
Component|tree-optimization |middle-end
Ever Confirmed|0 |1
--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> 2012-12-09 10:48:06 UTC ---
This is an ARM (both arm32 and arm64) specific issue due to the shifts being
"free". If you look at the mips assembly, it looks good for a dual issue
processor as it is scheduled as an add followed by a shift.
I think the issue is reassocdoes not know that shifts are free on arm.
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