[webkit-dev] arm jit

Oliver Hunt oliver at apple.com
Wed Jun 10 14:33:12 PDT 2009


The issue is that it compiling 5000 lines of libraries (possibly more)  
results in a significant amount of memory use, that's why we don't  
compile -- i don't believe there was a significant cpu time  
performance win (if any at all) from delaying function compilation.   
There was however a significant memory win for most pages the user  
visited.

--Oliver

On Jun 10, 2009, at 2:20 PM, Toshiyasu Morita wrote:

> --- On Wed, 6/10/09, Oliver Hunt <oliver at apple.com> wrote:
>
> > I doubt that eager compilation would be a good strategy for the  
> web, though,
> > since web pages tend to load very large libraries of functions,  
> while only calling a
> > small percentage of those functions.
>
> Turbo C compiled about 10,000 lines of source code per second on an  
> ancient 12 Mhz PC AT. It does register allocation, common  
> subexpression elimination, and a bunch of other classical compiler  
> optimizations.
>
> Most modern processors are from about 200 Mhz to about 3 Ghz, which  
> is significantly faster than a PC AT. If you use simple linear  
> extrapolation, that's a compile speed of about 160k-2m lines per  
> second. That seems adequate to compile even fairly large libraries  
> of functions.
>
> Toshi
>
>

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