Mail Archives: pgcc/1999/03/09/16:13:17
On Mon, Mar 08, 1999 at 08:45:32PM -0600, Steve Bergman wrote:
> I'm getting ready to recompile my RH5.2 system and 2.2.2 kernel. I have an
> AMDK6-2/300. Would "-O6 -march=amdk6 -mcpu=amdk6" be reasonable options to set
> in rpmrc? What is the status of "-fstrength-reduce" and "-funroll-all-loops"
strength-reduce is fixed. it was never broken enough to warrant turning it
off in the first place.
loop unrolling has a few bugs in pgcc-1.1.1 (as well as in egcs), most of
these seem to be gone in the snapshots.
> these days? Are they stable enough to compile my whole system with?
loop-unrolling + 1.1.1 is probably not.
> a bit unclear about the optimizations table in the faq. When an option is
> marked "U" but is shown to be invoked at, say, level -O4, what does that mean?
That there are known cases of it generating bad code.
> At the top of the table it says it "must be explicitly enabled in its -foption
> form". Does that mean that you have to specify both -O4 and -foption to use
> that optimization? It seems a bit ambiguous.
Well, that means it belongs into that optimization level, but _currently_
it is disabled. Some versions have it enabled, so I consider this useful
information nevertheless.
> I should add that this system is my own home system, and although I do most of
> my work on it, it is not a "critical production system" by any means. I can
> afford to be at least a bit adventuresome, in the interest of performance and
> testing. (At home, no one can here you scream... ;-) )
Then just use the highest optimization level and experiment. Its a bit
inconvinient when your libc breaks, though... In any case, while I can't
guarantee it, most problems that you can expect will not kill your data.
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