Re: RFC: ARM Cortex-A8 and floating point performance

On Wed, 2010-06-16 at 15:52 +0000, Siarhei Siamashka wrote:
> Hello,
>
> Currently gcc (at least version 4.5.0) does a very poor job generating single
> precision floating point code for ARM Cortex-A8.
>
> The source of this problem is the use of VFP instructions which are run on a
> slow nonpipelined VFP Lite unit in Cortex-A8. Even turning on RunFast mode
> (flush denormals to zero, disable exceptions) just provides a relatively minor
> performance gain.

> The right solution seems to be the use of NEON instructions for doing most of
> the single precision calculations.

Only in situations that the user is aware about -ffast-math. I will
point out that single precision floating point operations on NEON are
not completely IEEE compliant.

cheers
Ramana