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Re: GCC 4.5 Optimization Problem
- From: Brian Budge <brian dot budge at gmail dot com>
- To: Quant <carkaci at gmail dot com>
- Cc: gcc-help at gcc dot gnu dot org
- Date: Thu, 5 May 2011 14:19:51 -0700
- Subject: Re: GCC 4.5 Optimization Problem
- References: <31553457.post@talk.nabble.com>
On Thu, May 5, 2011 at 2:16 PM, Quant <carkaci@gmail.com> wrote:
>
> I have recently upgrade my Ubuntu from 10.10 to 11.04. GCC version is also
> upgraded from 4.4 to 4.5 automatically. However, some of my heavy math. C
> codes run slower when compiled with GCC 4.5.
> I have tried various optimization flags including "-fexcess-precision=fast".
> But nothing changes, it runs slower comparing to the executable compiled
> with GCC 4.4.
>
> By the way, I complied them with GCC 4.4 with "-03 -ffast-math". My machine
> is IMAC I7. Ubuntu is 64bit.
What kind of math... is there a small representative kernel of
operations you could show? Is it in loops or large flat computations?