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Re: Gcc optimization flags

From: "Zack Weinberg" <zack at codesourcery dot com>
To: Scott Robert Ladd <coyote at coyotegulch dot com>
Cc: Long Fei <lfei at ecn dot purdue dot edu>, gcc at gcc dot gnu dot org
Date: Tue, 05 Aug 2003 21:28:49 -0700
Subject: Re: Gcc optimization flags
References: <000601c35bc2$ccefda80$2c7b2e80@ee271dpc5><3F306F64.2070008@coyotegulch.com>

Scott Robert Ladd <coyote@coyotegulch.com> writes:

> Long Fei wrote:
>> It seems that without turning on the -O flag, other optimization flags
>> won't have any effect ?
>> Did anybody have any experience in using the flags separately rather
>> than -Ox ?
>
> The compiler performs several very basic optimizations when -O is in
> effect. Essentially, -O turns the optimizer on; the additional options
> then refine the optimization process.

Yep.  It is also worth pointing out that there are several
optimizations that are controlled only by -O level; they do not have
-f switches of their own.

zw

References:
- Gcc optimization flags
  - From: Long Fei
- Re: Gcc optimization flags
  - From: Scott Robert Ladd

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