Comments on: The Idée Fixe and the Perfected Profiler http://www.mirandabanda.org/cogblog/2008/12/30/the-idee-fixe-and-the-perfected-profiler/ Speeding Up Croquet and Squeak with a new open-source VM from Teleplace Mon, 05 Sep 2011 20:38:51 +0000 hourly 1 http://wordpress.org/?v=3.2.1 By: Claus Gittinger http://www.mirandabanda.org/cogblog/2008/12/30/the-idee-fixe-and-the-perfected-profiler/comment-page-1/#comment-4555 Claus Gittinger Mon, 05 Sep 2011 20:38:51 +0000 http://www.mirandabanda.org/cogblog/?p=16#comment-4555 Performance wise: it heavily depends; in "normal" situations (unless you have zillions of simple getters/setters/^self methods), it does not really make a significant difference; in the standard set of classes, these are relatively seldom (and some of them are never called, as they are redefined in concrete classes). As mentioned above: its main use is for those struct classes (and maybe self-like languages without inlining). But as soon as you do inlining, these few % of speedup will vanish anyway. So, you are probably right in not wasting too much effort on it... Performance wise: it heavily depends; in “normal” situations (unless you have zillions of simple getters/setters/^self methods), it does not really make a significant difference; in the standard set of classes, these are relatively seldom (and some of them are never called, as they are redefined in concrete classes). As mentioned above: its main use is for those struct classes (and maybe self-like languages without inlining). But as soon as you do inlining, these few % of speedup will vanish anyway. So, you are probably right in not wasting too much effort on it…

]]> By: Claus Gittinger http://www.mirandabanda.org/cogblog/2008/12/30/the-idee-fixe-and-the-perfected-profiler/comment-page-1/#comment-4554 Claus Gittinger Mon, 05 Sep 2011 20:22:12 +0000 http://www.mirandabanda.org/cogblog/?p=16#comment-4554 (you need an edit button for comments...) oops - I forgot: currently I pass the selector as extra argument (i.e. pushd rcvr; push selector; push args; push &ilc ...) For all non-performs, I could put the selector into the ilc struct, saving a push. However, the extra push is not very expensive, as the selector-push is an immediate push, which usually goes unnoticed between cycles... (you need an edit button for comments…)
oops – I forgot: currently I pass the selector as extra argument (i.e. pushd rcvr; push selector; push args; push &ilc …)
For all non-performs, I could put the selector into the ilc struct, saving a push. However, the extra push is not very expensive, as the selector-push is an immediate push, which usually goes unnoticed between cycles…

]]> By: Claus Gittinger http://www.mirandabanda.org/cogblog/2008/12/30/the-idee-fixe-and-the-perfected-profiler/comment-page-1/#comment-4553 Claus Gittinger Mon, 05 Sep 2011 20:16:48 +0000 http://www.mirandabanda.org/cogblog/?p=16#comment-4553 Eliot, I use the standard C calling sequence, with an indirect ILC (i.e. I do not patch the instruction (which may be in a shared readOnly code segment), but instead an indirect call through a slot of a structure. The address of the structure is passed with the call as extra argument; so my code looks more like: push rcvr push args push &ilcStruct call *(ilcStruct->cachedFunc) the cachedFunc of course points to the send-lookup initially, which patches ilcStruct->cachedFunc. The ilcStruct can of course hold more than just a cached func-ptr; it also holds the head of the polymorph cache chain, the last resolved class and some other info I might need (chaining them for ilc flushing, for example) Eliot,
I use the standard C calling sequence, with an indirect ILC (i.e. I do not patch the instruction (which may be in a shared readOnly code segment), but instead an indirect call through a slot of a structure. The address of the structure is passed with the call as extra argument; so my code looks more like:
push rcvr
push args
push &ilcStruct
call *(ilcStruct->cachedFunc)

the cachedFunc of course points to the send-lookup initially, which patches ilcStruct->cachedFunc. The ilcStruct can of course hold more than just a cached func-ptr; it also holds the head of the polymorph cache chain, the last resolved class and some other info I might need (chaining them for ilc flushing, for example)

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