Re: [9fans] p9/linux/fbsd compiler shootout

[Gaute B Strokkenes <gs234@cam.ac.uk>]

On Tue, 26 Feb 2002, andrey@lanl.gov wrote:
>> The compile time using for the BSD/2.95/no test looks *really* low;
>> are we sure about that number?  It's a very strange outlier, isn't
>> it?  I'll mostly ignore that one, because it is *such* a surprise;
>> GCC isn't normally thought to be that fast, but hey, maybe it
>> really is.
>>
> 
> several more tests yield exactly the same results -- FBSD 4.5 w/
> gcc2.95 takes about 18 seconds to compile.
> 
>> A total curiosity is that running the Linux binaries under
>> emulation in BSD is *faster* than running the native BSD binaries.
>> It's hard to imagine that the BSD team specially optimized that
>> case, does anyone have any knowledge or guesses?
>> 
> 
> gcc 3.0 on FBSD was locally compiled and installed (as was noted in
> the explanations), had it been taken from a binary package it _must_
> have been much faster (all we did was 'make; make install')...

Read the GCC installation manual: you're supposed to say "make
bootstrap", not just "make".  IIRC if you just use plain "make" what
you get is a compiler that is built with the system default compiler.
If you use "make bootstrap", then GCC is first built with the system
compiler, then that compiler is used to compile GCC again.  Then that
compiler builds GCC a third and final time.  The last two compilers
are compared byte-for-byte; they should be equal since GCC should
produce identical output independent of what compiler it is built
with.

-- 
Gaute Strokkenes                        http://www.srcf.ucam.org/~gs234/
I joined scientology at a garage sale!!