Re: GCC 4.5 Optimization Problem

[Brian Budge <brian dot budge at gmail dot com>]

On Thu, May 5, 2011 at 2:27 PM, Abdurrahman Carkacioglu
<carkaci@gmail.com> wrote:
> Something like following code.
>
> http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/MT2002/CODES/mt19937ar.c
>

fast-math will not typically affect this code.  The math here is
primarily integer arithmetic, and has a lot of loops.  Are you
generating floating point random numbers?  If so, and you can afford
the small precision penalty, you could precompute the divisions as
reciprocals, which are then multiplied at runtime.  Otherwise, you'll
need a profiler to guide you to the problematic lines of code.

If you can narrow it down to a missed loop-unroll or something
similar, likely someone on this list (other than me :) ) will be able
to help you further.

  Brian