gcc 4.5.0 with Graphite - building & testing

gcc 4.5.0 with Graphite - building & testing

[Solar Designer]

Hi,

I wrote a lengthy wiki page with step-by-step instructions and demos on
building/installing/using gcc 4.5.0 with Graphite under a non-root user
account (my test system only had gcc 3.4.5 installed).  I think those
instructions could be useful to some users of gcc, so feel free to copy
them or link to them.  At least I haven't seen similarly straightforward
yet very specific and complete instructions elsewhere.  The wiki page is:

http://openwall.info/wiki/internal/gcc-local-build

This wiki page also shows the following (as it goes through the
parallelization demos):

I encountered several shortcomings of gcc while testing its
parallelization capabilities.  This includes unreasonable non-use of
SSE2 with unsigned ints (whereas SSE2 is used just fine with signed
ones), and unreasonable non-parallelization when the loop index variable
is declared unsigned (auto-parallelization of the same loop does occur
when the index variable is signed).

I do not file bug reports for these just yet because I do not know what
the intended behavior is - maybe there is in fact some reason (unknown
to me) for avoiding SSE2 and parallelization for unsigned ints.

Also, I was not able to trigger an equivalent of OpenMP reduction
without in fact using an OpenMP directive.  Maybe this is as intended
for the time being, although perhaps this is an area for improvement.
Without this, auto-parallelization appears to be of little practical
use, because most (all?) loops that do get parallelized involve writes,
which, in my testing, almost implies that either their data does not fit
in cache or they incur cache coherence overhead.

I am not complaining (in fact, I am happy to see gcc gain these
features), nor am I asking for any help with this.  I am merely sharing
my findings in hope that someone will find this feedback useful. :-)

Thanks,

Alexander