GCC 4.0, Fast Math, and Acovea

[tbp]

On 5/3/05, Scott Robert Ladd <scott.ladd@coyotegulch.com> wrote:
> tbp wrote:
> Granted, POV-Ray may not be state-of-the-art, but then, I know quite a
> few people who say that (even legitimately) about just about every
> software product in existence.
True. Still, POV has evolved from dkbtrace and it shows sometimes.

> If you have a suggestion for better benchmarks, I'm listening. Is your
> ray tracer available?
It's way too rough for general consumption yet, and quite specialized
anyway (very large geometry).

With specific kludges for each compiler, here's the hierarchy for the
hand vectorized rendering:
ia32:	icc8.1, gcc4.1 (-5% at least), msvc2k3 (-20%)
x86-64:	gcc4.1, icc9.0 (-7% at least)
It varies a bit, depending on features being hammered by specific
scenes, but the order is unchanged (note that the x86-64 version has
only been tested on k8 so far).

GCC shows an edge in the SAH kdtree compiler part (branchy code) on
x86-64, with a >40% improvement over the ia32 versions (and icc9.1
which definitely gets lost).
That's more than welcome, given the time it takes to produce those
freaking trees :)

Anecdotically gcc is only one to get the parsing of large memory
mapped files right (or put another way, the idiom used), being 2x
faster than every other compilers on every platform.