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Re: Optimal compile flags for ultra2 & power2
- To: "David S. Miller" <davem at dm dot cobaltmicro dot com>
- Subject: Re: Optimal compile flags for ultra2 & power2
- From: John Carr <jfc at mit dot edu>
- Date: Tue, 22 Sep 1998 12:50:57 EDT
- Cc: shocking at prth dot pgs dot com, egcs at cygnus dot com
> I was wondering what flags people use for best FP performance on these -
>
> a) Sun ultra2
>
> -O2 -mtune=ultrasparc -fcall-used-g4 -fcall-used-g5 -fcall-used-g7
%g7 is used by the Solaris thread library, so don't use -fcall-used-g7
in multithreaded programs (which includes any program using XIL in
Solaris 2.6).
-mcpu=ultrasparc will enable the V9 floating point instructions and
should improve performance on an Ultra; code compiled with this switch
will not run on older SPARCs.