"Jeffrey J. Mountin" wrote:
> Successfully did a buildworld with -O -pipe -march=pentiumpro, installworld
> was good, remade /dev and built a generic kernel. Config'd my local kernel
> and within the first few lines of 'make depend' it bombed:
Sounds like one of those nasty gcc optimization bugs. I generally
build my kernel and world with -mpentium -O3 -pipe, and I haven't seen
any bugs at all. I build everything with these flags without
problems. The only problems I've see, as mentioned previously, was in
building Qt. I've gotten an "Internal compiler error" with those
flags, but reverting to what Troll put in qt/configs solved the
problems. Apparently, there's both compile-time and run-time bugs
with gcc's opt. code.
I think there are some bugs with the pentium-specific flags in gcc,
excluding the generic-pentium flag of -mpentium. I would try using
-mpentium -O3 -pipe --- I'm pretty confident that will solve your
problems, and you can still get generic pentium optimization levels.
Of course, I don't really know if there's anything to be gained by
using these flags over the stock -O -pipe -- but I do it anyways for
the psychological reassurance (placebo effect). I definitely think
building XFree86 with pentium opt. is a great idea. But with
buildworld and buildkernel, my advice would be to just use -mpentium,
as it's probably the "happiest medium" between pentium opt. and
stability. From what I've heard, compiling mission critical stuff
with -mpentiumpro is a bad idea. Hmmm... didn't -mpentiumpro come
from pgcc? I think the best place to use -mpentiumpro is in compiling
multimedia type stuff, where stability isn't important but speed is.
Basically, gcc is a very good compiler. But, it isn't exactly the
best compiler to use for optimization. Someone told me that Sun's and
DEC's compilers, for example, blow away gcc in terms of speed. But,
they aren't portable.
- Donn
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