Re: C compile time

[Dara Hazeghi <dhazeghi at yahoo dot com>]

Hello,

I've tried to update my measurements to include the
recommendations made on the list.

Current table is at:
http://www.myownlittleworld.com/computers/gcctable.html

(so as to avoid yahoo mail munging it).

Steve, you're right that -funit-at-a-time is
responsible for the slowdown at -O3. Without it,
results on mainline are quite similar to 3.3. I'll try
to record executable sizes when I get a chance. I
don't think this will be a good runtime benchmark,
because gcc is supposed to be largely impervious to
such optimizations, but if you think not, I can check
that too.

Andrew, your patch obviously helped enormously.
However, I tried it against tree-ssa and saw no
difference (beyond noise). Any ideas as to why?

Scott, I added -g to the table. Do you consider -pg
particularly important (from the real world)?

As mentioned in
http://gcc.gnu.org/ml/gcc/2003-06/msg01562.html, I'm
uncertain how to get results for -fsyntax-only, but
I'll certainly check.

Regarding icc, I don't care much for it, but it was
the only other C compiler I found for x86/Linux that
was easy to get ahold of. I included it for reference
purposes. If anybody has a suggestion for another
Linux C compiler, by all means, tell me.

All in all, I'm pleased that this issue is getting IMO
some much deserved attention, and glad that the issues
weren't as severe as might have initially seemed.

Cheers,

Dara

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