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Re: Complex divide vs -ffast-math
- From: Dale Johannesen <dalej at apple dot com>
- To: Toon Moene <toon at moene dot indiv dot nluug dot nl>
- Cc: Dale Johannesen <dalej at apple dot com>, gcc-patches at gcc dot gnu dot org
- Date: Mon, 28 Jan 2002 15:20:37 -0800
- Subject: Re: Complex divide vs -ffast-math
On Monday, January 28, 2002, at 03:16 PM, Toon Moene wrote:
> Oh, yeah - a typical example where this optimisation would help.
> According to the Fortran promotion rules, DFLOAT(NX*NY*NZ) has to be
> promoted to DOUBLE COMPLEX before performing the division.
>
> However, it is a (triple-)loop invariant quantity, so changing this from
> a complex divide into a complex multiply is a definite win.
>
> How complex :-) is it to do this right w.r.t. RDIV ?
Probably not very. I'll look at it if you want, but might not get to it
right away.