970917 on mips-sgi-irix6.2, haifa disabled: many problems

[Zack Weinberg]

On Sun, 28 Sep 1997 01:45:31 -0600, Jeffrey A Law wrote:
>
>  [Along the same lines, It Would Be Nice if
>  > one could disable various of the multilib targets; for example, I can't us
>e
>  > -mabi=64 code on this beast and would just as soon save the space.]
>You might be interested in --disable-multilib -- it's a configure
>option that simply disables multilibs.
>
>If you come up with a scheme to improve multilib, submit it.  We're
>more than open to schemes to improve multilib.

Well, what I was thinking of was a finer-grained version of
--disable-multilib.  How about --enable-multilib=LIST to say, I want this,
this, and this?  Also, for cases (xcoff/elf, n32/64) where the compiler has
multiple output backends, the configure switch should cut out the code for
the undesired backends.

One could take this to its logical conclusion, and ask for compile time
switches to exclude all but one chip subarchitecture (e.g. you have a farm
of identical computers, and you never want to compile for any other subarch)
but I think this would be overkill; subarchitectures don't bloat the
compiler enough to be worth the hassle of #ifdef'ing them all.  I would
however like to see some easy way to change the default set of -m switches
gcc uses.  SGI's compilers for example read an envariable (SGI_ABI) and a
file in /etc to decide which ABI to default to.  There's also a nice feature
of Sun's compilers, the -native switch, which means "tune code and issue
instructions for the chip I'm compiling on." This may be too hard to
implement (how do you know which chip you're on?) though.

zw