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Re: BB reorder forced off for -Os

From: Steven Bosscher <stevenb dot gcc at gmail dot com>
To: Ian Bolton <bolton at icerasemi dot com>
Cc: gcc at gcc dot gnu dot org
Date: Tue, 23 Mar 2010 23:30:45 +0100
Subject: Re: BB reorder forced off for -Os
References: <4D60B0700D1DB54A8C0C6E9BE69163700E08F38E@EXCHANGEVS.IceraSemi.local> <571f6b511003190943r65c1bde8kd0b136fa08504d9a@mail.gmail.com> <4D60B0700D1DB54A8C0C6E9BE69163700E08FFC2@EXCHANGEVS.IceraSemi.local> <C681F561-A39B-4319-8ECF-765095982882@blueteddy.net> <4D60B0700D1DB54A8C0C6E9BE69163700E126D3E@EXCHANGEVS.IceraSemi.local>

On Tue, Mar 23, 2010 at 7:05 PM, Ian Bolton <bolton@icerasemi.com> wrote:
> Is there any reason why BB reorder has been disabled
> in bb-reorder.c for -Os, such that you can't even
> turn it on with -freorder-blocks?

No, you should have the option to turn it on if you wish to do so. If
that is not possible, I consider this a bug. If you open a PR and
assign it to me, I'll look into it.

> From what I've heard on this list in recent days,
> BB reorder gives good performance wins such that
> most people would still want it on even if it did
> increase code size a little.

FWIW there is already a PR with a request to add heuristics for
BB-reorder to optimize for size.

Ciao!
Steven

Follow-Ups:
- Re: BB reorder forced off for -Os
  - From: Dave Hudson

References:
- Understanding Scheduling
  - From: Ian Bolton
- Re: Understanding Scheduling
  - From: Steven Bosscher
- RE: Understanding Scheduling
  - From: Ian Bolton
- Re: Understanding Scheduling
  - From: Dave Hudson
- BB reorder forced off for -Os
  - From: Ian Bolton

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