Re: [LAD] Optimisations

On Mon, 18 Aug 2014 18:36:35 +0000
Fons Adriaensen <fons@email-addr-hidden> wrote:

> On Mon, Aug 18, 2014 at 06:11:33PM +0100, Will Godfrey wrote:
> > A long time ago ... in a land far away :)
> > I did some assembler programming on the Acorn Archimedes (ARM 2/3) and worked
> > out a series of additions and subtractions that would perform very fast
> > multiplication of awkward numbers by known amounts.
> >
> > Is there any point in doing this for C programs, or are modern compilers
> > sophisticated enough to do such things themselves?
> >
> > If anyone is interested *7 is:
> > RSB R1, R0, R0, LSL #3
>
> :-) Memories... I love ARM assembly...
>
> Modern compilers will do such things. If they exploit other
> features of the ARM (such as all instructions being conditional)
> I don't know, but it's very well possible.
>
> Ciao,

Thanks for the responses guys. I think it's a case of let the compiler do the
work. Oh, and yes, I found ARM assembly a dream to work with, although I don't
know what it's like these days. There have been quite a lot of extensions I
believe.

-- 
Will J Godfrey
http://www.musically.me.uk
Say you have a poem and I have a tune.
Exchange them and we can both have a poem, a tune, and a song.
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