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Re: i386 performance problem due to local-alloc.c change
- To: john at feith dot com (John Wehle)
- Subject: Re: i386 performance problem due to local-alloc.c change
- From: Jeffrey A Law <law at cygnus dot com>
- Date: Wed, 24 Jun 1998 01:12:30 -0600
- cc: egcs-patches at cygnus dot com
- Reply-To: law at cygnus dot com
In message <199806240650.CAA13269@jwlab.FEITH.COM>you write:
> I seem to be seeing around a 10 percent performance hit when
> running the crafty chess benchmark and the Brl-Cad raytracing
> benchmarks on an Intel Pentium II with:
>
> Tue Jun 9 12:36:16 1998 Jeffrey A Law (law@cygnus.com)
>
> * Makefile.in (local-alloc.o): Depend on insn-attr.h.
> * local-alloc.c (block_alloc): Avoid creating false
> dependencies for targets which use instruction scheduling.
>
> installed. If I remove this patch then life gets better (not to
> mention faster :-).
Hmmm, I thought the x86 didn't do any local register allocation due to
the definition to CLASS_LIKELY_SPILLED_P. So I'm a little suprised.
One thought would be to disable that code if SMALL_REGISTER_CLASSES
is nonzero. That's probably the right thing to do.
jeff
ps. It's as much as a 25% improvement for ugly Fortran code on my PAs :-)