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Re: Behaviour of -msse -march=athlon
- From: Ian Lance Taylor <iant at google dot com>
- To: Ryan Hill <dirtyepic at gentoo dot org>
- Cc: gcc-help at gcc dot gnu dot org
- Date: 16 Sep 2007 11:19:21 -0700
- Subject: Re: Behaviour of -msse -march=athlon
- References: <fcibum$dov$1@sea.gmane.org>
Ryan Hill <dirtyepic@gentoo.org> writes:
> Are -march options expected to override any relevant options specified
> previously on the command line?
No. -march should only override previous -march options. Doing
anything else is complicated and error-prone.
That said, I think it would be reasonable if the compiler issued
warnings about incompatible options after all options have been
parsed.
> It appears in GCC-4.2.0 that SSE movss
> instructions will be generated when for example the following code is compiled
> with -msse -march=athlon:
Don't do that, then.
Ian