[FoRK] The rise of the stupid?

Eugen Leitl eugen at leitl.org
Sun Feb 27 23:38:36 PST 2005


On Sun, Feb 27, 2005 at 09:07:27PM +0000, Andy Armstrong wrote:
> On 27 Feb 2005, at 20:47, zuzu wrote:
> >i'm curious to know what software you write where a compiler such as
> >gcc just isn't good enough that you have to try out-wit it with arcane
> >syntax.  i admit there's plenty i don't confront w/r/t IO and
> >databases as well.
> 
> Well it depends what you mean by 'arcane syntax'. I thought you were 
> suggesting (previously) that any use of C constituted 'arcane 
> syntax'...

Anything you need to outwit the idiot compiler will look contorted.
Here: http://leitl.org/docs/comp/AMD_block_prefetch_paper.pdf
If you don't want to read the whole paper, skip to the end.
 
> Most recently the only time I've needed to 'outwit' the compiler was 
> writing an off-screen bitmap graphics library (somewhat like GD). For 
> pixel level manipulations including the alpha compositing and 
> anti-aliasing I found that I could get huge performance gains by hand 
> optimising things like the inner loop of the horizontal line drawing 
> code. Admittedly that kind of thing is rare. I'm pretty sure though 

It's rare because few people bother.

> that our original point of entry here was your assertion that using C 
> integer arithmetic to decompose a time in ms into minutes and seconds 
> was a premature or unwise optimisation :)

-- 
Eugen* Leitl <a href="http://leitl.org">leitl</a>
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