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Re: How to tune gcc for different x86 host and target cpus?

From: Michael Roth <mroth at nessie dot de>
To: Ian Lance Taylor <ian at wasabisystems dot com>
Cc: gcc-help at gcc dot gnu dot org
Date: Wed, 12 May 2004 21:43:59 +0200
Subject: Re: How to tune gcc for different x86 host and target cpus?
References: <40890299.1070608@nessie.de> <m3smesdgem.fsf@gossamer.airs.com>

Ian Lance Taylor wrote:

Michael Roth <mroth@nessie.de> writes:
But how can I tell the configure script that the compiler itself
should be optimized for a different cpu architecture?
One way is to set CFLAGS when you compile.  The default value for
CFLAGS is "-g -O2" (when compiling with gcc).
Example #1: Host and build are athlon-xp, target should be pentium.

make CFLAGS="-g -O2 -march=athlon"

Thank you. This did the job.

I think that if you set the environment variable CFLAGS when you run
configure, it will be picked up and stored in the Makefile.  Try it by
looking at the definition of CFLAGS in the top level Makefile after
you run configure.

I'm not sure, I tried this before I posted to this list, and I think it didn't worked well. But I could be wrong.

Michael

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