2013/6/27 Levente Uzonyi <leves@elte.hu>

On Wed, 26 Jun 2013, Guillermo Polito wrote:

On Wed, Jun 26, 2013 at 11:20 PM, Levente Uzonyi <leves@elte.hu> wrote:
� � � On Wed, 26 Jun 2013, Cl�ment Bera wrote:

� � � � � � Actually this code:�
� � � � � � True basicNew ifTrue: [ "some code" ]
� � � � � � works fine on the latest Pharo 3 because of Opal :)

So the Opal compiler lacks important optimizations. :)

Actually Opal generates almost the same bytecode as the old compiler. As a proof, Benchmarks run at the same speed when compiled with one or the other compiler. So no lack of optimizations.

Moreover Pharo and Squeak cannot be compiled without optimizing control flow structure or the compilation fails by image crash. This is due for example to the implementation of BlockClosure>>whileTrue: .

�

Not at all. In fact, the the code is optimized and falls back to the normal lookup in case of exceptional #mustBeBoolean, so the existing code keeps running the same speed ;)

So it generates a bunch of extra bytecodes for every #ifTrue:, #ifFalse:, #ifTrue:ifFalse: and #ifFalse:ifTrue: messages, in order to make this thing work? Or is there a trick to avoid the duplicaiton of the code in the blocks?

I understood the problem.�

In Pharo 3 we will support conditional optimized messages ( #ifTrue:, #ifFalse:, #ifTrue:ifFalse: and #ifFalse:ifTrue: ) sent on non boolean receiver. However, this feature will be slow, so one should not use it too much (as #become:, #isKindOf:, ...). Basically Opal compiles on the fly without optimizing it the conditional messageNode as a DoIt, run it, and jump in the context to the pc corresponding to the next ast node. We don't generate extra bytecode as you suggested, because it will grow the size of the image a lot and slow down the system with extra conditions.

Right now the feature is still under development and very buggy (it is just a prototype). It is activated only when Opal is set as default compiler, which is wrong, and there is a bug report. This bug report will be fixed during the sprint on Friday.

So actually I didn't look carefully enough but:

True basicNew ifTrue: [ "some code" ]

works fine because it sends it to a NonBooleanReceiver but Pharo 3 supports #ifTrue: sent on a NonBooleanReceiver.

�

However, what you can do in Pharo 3 / Opal if you know�explicitly that you will send the optimized message to a NonBooleanReceiver, to avoid slowness due to on the fly do it compilation, you can specify�it to the compiler in the class:

MyClass class>>#compiler
� � � � ^ super compiler options: #(- optInlineIf)

or in the method :

MyClass>>#foo
� � � � <compilerOptions: #(- optInlineIf)>
� � � � ^ #myNonBooleanObject ifTrue: [ 1 ] ifFalse: [ 0 ]

There are different options like this one. I wrote them down here to remember (section compilerOptions):
http://clementbera.wordpress.com/2013/05/28/modular-compilation-with-opal/

But it is not very nicely written, I've just write it to remember ..

Compiler options as this one are not for daily use, there are here to enable some stuff like boolean proxies.

Levente

�

� � � Levente

� � � � � � But nice trick for the old compiler :)

� � � � � � 2013/6/26 Nicolas Cellier <nicolas.cellier.aka.nice@gmail.com>
� � � � � � � � � Because you don't know the tricks... This one should be just fine

� � � � � � � � � True basicNew ifTrue: [ "some code" ] yourself

� � � � � � 2013/6/26 Cl�ment Bera <bera.clement@gmail.com>
� � � � � � � � � True basicNew ifTrue: [ "some code" ]

� � � � � � hehe raises NonBooleanReceiver :)

� � � � � � 2013/6/26 Camillo Bruni <camillobruni@gmail.com>
� � � � � � � � � why not, let's "forbid" them with an error message!

� � � � � � � � � => maybe you can and error to #become: on nil / true / false as well?

� � � � � � � � � On 2013-06-26, at 14:20, Torsten Bergmann <astares@gmx.de> wrote:

� � � � � � � � � > Boolean new � � � �-> error
� � � � � � � � � > Boolean basicNew � -> is possible
� � � � � � � � � >
� � � � � � � � � > should we care?
� � � � � � � � � >

--
Cl�ment B�ra

Mate Virtual Machine Engineer

B�timent B 40, avenue Halley 59650�Villeneuve d'Ascq