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Target CPU default selection on alpha
- To: egcs at egcs dot cygnus dot com
- Subject: Target CPU default selection on alpha
- From: Rainer Orth <ro at TechFak dot Uni-Bielefeld dot DE>
- Date: Fri, 18 Dec 1998 22:26:21 +0100 (MET)
Currently gcc/configure.in sets TARGET_CPU_DEFAULT for alpha* targets based
on the cpu type of the machine used to configure and build gcc, as
determined by config.guess (alpha, alphaev5, alphaev56, alphapca56,
alphaev6). While this is convenient for a single machine, I suppose it may
cause problems when the resulting gcc is run on a machine with a different
cpu type: e.g. configured for a 21164/ev5, but run on a 21064/ev4.
I'm not sure if this really causes problems on various alpha cpus
(cf. SPARC: using hardware multiplication on SPARC V7 machines causes
kernel emulation of the relevant instructions), but its more in line with
the treatment of other processors to leave this choice to the user (via
--with-cpu=).
Rainer
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Rainer Orth, Technical Faculty, University of Bielefeld
Internet: ro@TechFak.Uni-Bielefeld.DE