[Squeak-VMdev] right to left (was: Versiojn 4 changes)

[Jecel A. Jr <je...@me...>]

Ooops... I sent this only to Ian the first time instead of the list. He 
wrote a very nice reply giving even more examples of why this is a good 
idea.

On Wednesday 07 April 2004 22:02, Ian Piumarta wrote:
> Which reminds me of something else Dan & I talked about in the past:
> evaluating arguments from right to left.  Saves an awful lot of
> tedious peeking into the middle of the stack to pick up the receiver.
> (Combined with the above, potentially wins Really Big for 386 too.
> OTOH, the tradeoffs for register architectures are a little more
> complex.)

My Neo Smalltalk evaluates right-to-left. That lets me get by with just 
one send instruction. The first instructions in a compiled method grab 
the right number of arguments from the caller's stack. Unless it is a 
short leaf method - in that case it can skip creating its own stack and 
run directly with the caller's stack. This is a very common case since 
I currently do very little inlining (just the usual ifTrue: stuff).

In the green book Dan mentioned that the change to left-to-right from 
Smalltlak-78 to -80 was supposed to make people stop complaining about 
surprising results and to make creating really simple compilers 
possible. I didn't get this last part as the right-to-left order is 
easier in the recursive compilers I have written so far.

-- Jecel
P.S.: I hope comparing how my own and other implementations (I am very 
familiar with Self, for example) do things isn't too annoying. If it 
is, please let me know