Re: [RFC] Header organization of -base & -gui

[Lars Sonchocky-Helldorf]

On 03.07.2003 18:54:16 Nicola Pero wrote:
>> - NeXT/Apple runtime is known/believed to perform better than GNU
>> runtime.
>
>Hmmm.  Do you have benchmarks ?  I'd be interested in them if you have.
>
>I thought this was a confused matter open to discussion, with pros and
>cons on each side.
>
>But the Apple runtime performs better on class method invocations - 
that's
>a fact (I hoped to have the time to fill the gap at some point, but I
>never found that time <wishful sigh>). 

The Apple Runtime uses a cache for Classes and Methods. The name of the 
function in objc4 is

_class_lookupMethodAndLoadCache ()

which gets called by 

objc_msgSend ()

This cache I believe is also the main reason why GNUstep-base doesn't work 
with the Apple runtime:

If a class or method is currently not in cache, 
_class_lookupMethodAndLoadCache () calls class_initialize () which 
subsequently invokes +[NSObject initialize]. If then in turn there is any 
objc message in +[NSObject initialize] this will result in a call to 
objc_msgSend () and _class_lookupMethodAndLoadCache () again. But because 
the class is not loaded yet this ends up in a loop with no good end ;-). 
An example stacktrace of this behaviour is at the end of:

http://groups.google.com/groups?selm=DD750B82-9918-11D6-B3A3-0030654C2998%40hamburg.de&output=gplain


>The GNU runtime has typed
>selectors though, and it's more portable.

Apple's runtime uses assembler and therefore is only working on PPC and 
x86.

>
>
>

greetings, Lars