[comp.arch] MIPS Performance Brief - errata

mash@mips.UUCP (John Mashey) (11/04/87)

A few errata, passed along by David Hough:

>-On levels:  Sun's don't correspond on MIPS's.  -O1 is peephole only.
>-O2 does global optimization on local variables.  -O3 does global
>optimization of globals and pointers.  -O4 does something else that I don't
>understand (doesn't seem to affect floating point).  We do nothing
>interprocedural at any level.
(MASH: O1 corresponds pretty well, and our O2 is somewhere between Sun's
O2 and O3, I think.)

(MASH: I weren't sure what they did, except I knew -O4 didn't do
inlining, which is why I cited the Sun -O4 number for Dhrystone.)

>"Sun 4/260 w/FPA" is a misleading citation since all Sun-4's have
>floating point hardware standard.  So "Sun-4/260" is what to call it.

>Spice 2G6 has compiled correctly at -O3 (the highest Fortran level)
>for many months.  One module of Spice 3b1 doesn't compile at -O3, but
>that's irrelevant for Fortran.
Oops! This was a real goof.  I'd remembered the non-compile,
and wrongly associated that with 2G6, not 3B1.

Needless to say, if anybody else finds factual errors, especially in
numbers for their machines, please pass them along.
-- 
-john mashey	DISCLAIMER: <generic disclaimer, I speak for me only, etc>
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