That's it, the backward jumps use jumpFalse: and jumpTrue:.  It rings a 
bell.

I am trying to transform these jumps to equivalent msg sends, only when the 
receiver is not the expected type.  This way, the normal fast transform 
works most of the time and when it is the wrong receiver we get a msg send 
in the image that I can intercept.  The best of both worlds.  Unfortunately 
it more than doubles the bytecodes for these composite constructs, so I'd 
love to figure out the most compact forms.

Perhaps the way to go is to define bytecodes for all combinations like
    jumpFalseForIfTrue:
    jumpFalseForIfFalse:
    jumpFalseForIfTrueIfFalse:
    jumpFalseForWhileFalse:
    jumpTrueForWhileTrue:
    jumpFalseForToDo:
and so on.  Then I would need to figure out how to capture the blocks.

Rob

----- Original Message ----- 
From: "nicolas cellier" <ncellier at ifrance.com>
To: <squeak-dev at lists.squeakfoundation.org>
Sent: Friday, October 19, 2007 12:17 PM
Subject: Re: runtime compiled method optimizations


> You will also have backward jumps generated by loops (to:do: whileTrue: 
> whileFalse:)...
>
> Though you might be able to transform all these jumps in equivalent 
> message send (See Decompiler), that's might be impracticle to do that at 
> interpreter level.
>
>
> Rob Withers a écrit :
>>
>> ----- Original Message ----- From: "Igor Stasenko" <siguctua at gmail.com>
>> To: "The general-purpose Squeak developers list" 
>> <squeak-dev at lists.squeakfoundation.org>
>> Sent: Thursday, October 18, 2007 11:58 PM
>> Subject: Re: runtime compiled method optimizations
>>
>>
>>> On 19/10/2007, Rob Withers <reefedjib at yahoo.com> wrote:
>>>> Igor, I'm afraid you've lost me.  What would the bytecodes look like in 
>>>> your
>>>> proposal?  From what you've said, wouldn't the #jumpFalse need to know 
>>>> what
>>>> the literal to send is?  I also don't understand how it would extract 
>>>> the
>>>> block contents.
>>>
>>> You don't need to change bytecode. Just by analysing that jump
>>> bytecode jumps over a block. Then you can assume that bytes between
>>> jump bytecode and byte where it points to is the block body.
>>> So, you can do the trick by changing implementation of #jumpFalse.
>>> By sending #IfTrue: message to receiver and checking the result.
>>
>> I'm still not getting it.  I am all about getting this functionality in 
>> the most compact form.  Are you saying that I should stick to the 
>> following bytecodes?
>>
>> 17 <10> pushTemp: 0
>> 18 <9B> jumpFalse: 23
>> 19 <10> pushTemp: 0
>> 20 <20> pushConstant: 4
>> 21 <B0> send: +
>> 22 <7C> returnTop
>> 23 <78> returnSelf
>>
>> Then if I am reading you right, the block is defined as
>>    PC start of block := the PC of the jumpFalse: + 1
>>    PC end of block := the PC of the arg to the jumpBlock - 1
>> but I don't see where you setup and send the #blockCopy:
>>
>> I believe, but I am not sure, the #jumpFalse: is not only used for 
>> #ifTrue:, ifFalse:. ifTrue:ifFalse: and #ifFalse:ifTrue:, plus I want to 
>> be able to distinguish between these 4 methods.  Unless they all get 
>> transformed to #ifTrue:ifFalse: with appropriate nil blocks...
>>
>> Still, I am having a hard time understanding how #jumpFalse: suddenly 
>> knows to test for boolean (better than the testLocalReference), then if 
>> it is not boolean, instead of sending mustBeBoolean, do a couple of block 
>> copies and send #ifTrue:ifFalse:.  Can it do all that?  Can we have it 
>> scan the bytecodes of the current method to make decisions about the 
>> boundaries of the block copies?  Are we sure it should always send 
>> #ifTrue:ifFalse:?  You raise some interesting questions.
>>
>> Rob
>>
>>>
>>>>
>>>> thanks,
>>>> Rob
>>>>
>>>>
>>>> ----- Original Message -----
>>>> From: "Igor Stasenko" <siguctua at gmail.com>
>>>> To: "The general-purpose Squeak developers list"
>>>> <squeak-dev at lists.squeakfoundation.org>
>>>> Sent: Thursday, October 18, 2007 3:06 PM
>>>> Subject: Re: runtime compiled method optimizations
>>>>
>>>>
>>>> > No, i think you'd better change the implementation of #jumpFalse
>>>> > bytecode.
>>>> > If you see that receiver is non-local , then simply do message send.
>>>> > And, i think you can safely use info from jump bytecode to extract
>>>> > block contents
>>>> > (bytes 19 - 22 is the block body).
>>>> >
>>>> > On 19/10/2007, Robert Withers <reefedjib at yahoo.com> wrote:
>>>> >> Hi all,
>>>> >>
>>>> >> I have a simple method containing an ifTrue: message.  I have
>>>> >> compiled it normally, which uses macro transformations:
>>>> >>
>>>> >> 17 <10> pushTemp: 0
>>>> >> 18 <9B> jumpFalse: 23
>>>> >> 19 <10> pushTemp: 0
>>>> >> 20 <20> pushConstant: 4
>>>> >> 21 <B0> send: +
>>>> >> 22 <7C> returnTop
>>>> >> 23 <78> returnSelf
>>>> >>
>>>> >> and I have compiled it using Klaus Witzel's nifty compiler changes 
>>>> >> to
>>>> >> remove macro transformations and the result is an explicit message
>>>> >> send of #ifTrue:
>>>> >>
>>>> >> 21 <10> pushTemp: 0
>>>> >> 22 <89> pushThisContext:
>>>> >> 23 <75> pushConstant: 0
>>>> >> 24 <C8> send: blockCopy:
>>>> >> 25 <A4 04> jumpTo: 31
>>>> >> 27 <10> pushTemp: 0
>>>> >> 28 <21> pushConstant: 4
>>>> >> 29 <B0> send: +
>>>> >> 30 <7C> returnTop
>>>> >> 31 <E0> send: ifTrue:
>>>> >> 32 <87> pop
>>>> >> 33 <78> returnSelf
>>>> >>
>>>> >> I would like to check the receiver of the ifTrue:, the 1st method 
>>>> >> arg
>>>> >> in this case (Temp: 0), to see if a certain situation exists (is it 
>>>> >> a
>>>> >> local reference to an object?).  If it is true, I would like to run
>>>> >> the optimal code from the first example, instead of the longer 
>>>> >> second
>>>> >> example.   How could we do that?  Something like this?  Could it be
>>>> >> done entirely by the compiler, given the existence of the bytecode
>>>> >> routine for #testLocalReference?
>>>> >>
>>>> >> 21 <10> pushTemp: 0
>>>> >> 22 <??> testLocalReference
>>>> >> 23 <??> jumpFalse: 30
>>>> >> 24 <10> pushTemp: 0
>>>> >> 25 <??> jumpFalse: 40
>>>> >> 26 <10> pushTemp: 0
>>>> >> 27 <20> pushConstant: 4
>>>> >> 28 <B0> send: +
>>>> >> 29 <7C> returnTop
>>>> >> 30 <89> pushThisContext:
>>>> >> 31 <75> pushConstant: 0
>>>> >> 32 <C8> send: blockCopy:
>>>> >> 33 <?? ??> jumpTo: 38
>>>> >> 34 <10> pushTemp: 0
>>>> >> 35 <21> pushConstant: 4
>>>> >> 36 <B0> send: +
>>>> >> 37 <7C> returnTop
>>>> >> 38 <E0> send: ifTrue:
>>>> >> 39 <87> pop
>>>> >> 40 <78> returnSelf
>>>> >>
>>>> >>
>>>> >> Thanks!
>>>> >> Rob
>>>> >>
>>>> >>
>>>> >>
>>>> >
>>>> >
>>>> > --
>>>> > Best regards,
>>>> > Igor Stasenko AKA sig.
>>>> >
>>>> >
>>>>
>>>>
>>>>
>>>
>>>
>>> -- 
>>> Best regards,
>>> Igor Stasenko AKA sig.
>>>
>>>
>>
>>
>>
>
>
>