In <Pine.3.89.9511211504.A25933-0100000@lafcol>
On Tue, 21 Nov 1995 15:24:00 -0500 (EST)
Andy Dougherty <doughera@lafcol.lafayette.edu> writes:
>On Tue, 21 Nov 1995, Joe Marzot wrote:
>
>> just curious - why is the default optimaization for gcc on sunos4_1 -O
>> instead of -O2 or something
>
>Threre's nothing special about gcc on sunos4_1 here. The default
>optimization for everybody everywhere is -O, unless someone specifically
>patched a hints file to do otherwise. '-O' is the only portable
>way to specify optimization. Not all systems support the -O2
>syntax.
But all gcc's do, and we already test for gcc.
There is some case for making
gcc's default -O2. -O2 enables instruction scheduling which on superscalar
machines is a major win. The snag is that you probably need a -msupersparc
to make scheduling correct.
>
>If you want to propose something special for SunOS, you certainly may
>submit a patch for the hint file. I'm not sure why you would want to
>single out gcc and not do something similar with cc. Also, why stop at
>-O2? Do you trust -O[3456]?
-O[3...] did not actually do anything more than -O2 (on SPARC)
last time I looked (about a year ago).
>
>Beware, compiling toke.c with higher levels of optimization may give
>smaller systems fits. You probably want to check this out before
>proposing it for everyone.
>Me, I just do
> sh Configure -Doptimize='whatever'
>if I don't want '-O'.
Same here. (It is always -g -O2 with gcc modified to do
-msupersparc -mno-v8 by default).