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Re: [PATCH rs6000] Increase register move cost for LR/CTR
- From: Pat Haugen <pthaugen at us dot ibm dot com>
- To: David Edelsohn <dje at watson dot ibm dot com>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Wed, 16 Apr 2008 10:42:26 -0500
- Subject: Re: [PATCH rs6000] Increase register move cost for LR/CTR
David Edelsohn <dje@watson.ibm.com> wrote on 04/15/2008 06:59:19 PM:
> * config/rs6000/rs6000.c (rs6000_register_move_cost): Increase cost
of
> LR/CTR moves.
>
> Okay.
>
> Does this change help IRA?
>
Yes, this change eliminated the 24% degradation I was seeing on the cpu2000
facerec benchmark with -fira on Power6. Given Andrew's Cell concern with
this patch, would it be preferable to make the change cpu specific
(starting with just Power6 for now since that's where the bigger latencies
came in to play)?
-Pat