Re: bit.lshift and performance - luabitop v.s. lua-5.2.0-work4

[KHMan <keinhong@...>]

On 10/13/2010 9:33 PM, David Kastrup wrote:
> KHMan writes:
> > Anyway most app developers do not need to code DCTs and FFTs
> > nowadays.
>
> I find that C compilers tend to be actually astonishingly bad at that.
> Coding the inner loops in assembly language can often halve the
> execution time.  Somehow the optimizers/register allocators don't seem
> to like complex butterflies all too well.

Exactly.

This was why I chose *specifically* DCT and FFT as a 
conversational gambit -- most widely-released mainstream 
implementations are still optimized in assembly language.

Mortals like me consume them in ready-made libraries. Would be 
interested to see what other scripting languages are doing in this 
respect.

A few hundred million ops per second doing them on Lua seemed far 
off enough that it seemed to me like a reasonable future target, 
but not something that can be currently done. Now since I was 
thinking only in terms of Lua, it seemed reasonable enough to me. 
Obviously, I am a horrid dunce.

--
Cheers,
Kein-Hong Man (esq.)
Kuala Lumpur, Malaysia