From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeffrey A Law To: Rainer Orth Cc: Richard Henderson , egcs@egcs.cygnus.com Subject: Re: Target CPU default selection on alpha Date: Tue, 22 Dec 1998 12:05:00 -0000 Message-id: <8103.914357051@hurl.cygnus.com> References: <13950.40985.756783.276976@xayide.TechFak.Uni-Bielefeld.DE> X-SW-Source: 1998-12/msg00862.html > >From a quick check of current CVS configure.in, the c*-convex-*, several > hppa1.1-*-* and hppa2*-*-*, the i[4-7]86-*-* and alpha*-*-* targets behave > this way. All others default to the least common denominator. > > > There isn't any kind of consistency in this area. For example the ppc > > defaults to "common" mode. > > Than perhaps now it's time to become consistent, or at least document why > some targets have a different default. I don't think we need to be consistent in this area. Doing so can greatly impact performance on some machines. > What are the primary arguments against defaulting to least common > denominator, beyond performance? Performance. > I think the decision should be left to the user. Or at least the user > should be aware of the choice and it's consequences. The user still has the ability to configure for a common toolchain by using the least common denominator configure string. Most (all) ports also have options which allow for generation of code for a particular processor. So for the PA one could configure with: configure hppa1.0-hp-hpux10.20 Which would build a compiler which defaulted to hppa1.0 code generation, which is the least common denominator for the PA architecture. Or, given any PA compiler, the user can force code generation for a particular chip with -mpa-risc-X-Y where X-Y represents different variants within the PA family (1-0, 1-1, 2-0, and so on in the future). jeff