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Re: Apple's -fast option for gcc

From: Steven Bosscher <s dot bosscher at student dot tudelft dot nl>
To: Martin Brain <mjb at cs dot bath dot ac dot uk>
Cc: Russ Allbery <rra at stanford dot edu>, gcc at gcc dot gnu dot org
Date: Wed, 17 Sep 2003 20:43:01 +0200
Subject: Re: Apple's -fast option for gcc
References: <D85F773C-E932-11D7-8F0D-003065A77310@apple.com> <87znh3qq2i.fsf@windlord.stanford.edu> <1063821418.32137.513.camel@ralph.cs.bath.ac.uk>

Op wo 17-09-2003, om 19:56 schreef Martin Brain:
> As I understand it the number of levels refers to the scope the
> optimisations work in.  -O1 is within basic blocks, -O2 is between basic
> blocks, -O3 is across the entire function.  Ofcourse not all
> optimisations can be categorised like this and so have been fitted to
> the nearest appropriate level.

This is not quite true, and certainly not for GCC 3.5 and beyond with
tree-ssa merged.  All SSA passes are global, and they're (at present)
all enabled at -O1.

Gr.
Steven

References:
- Re: Apple's -fast option for gcc
  - From: Mike Stump
- Re: Apple's -fast option for gcc
  - From: Russ Allbery
- Re: Apple's -fast option for gcc
  - From: Martin Brain

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