Performance of [ * ] repeat vs [ * . true ] whileTrue

> On Aug 14, 2016, at 4:42 PM, Henrik Nergaard <[hidden email]> wrote:
>
> Hi,
>
> Why  is “[ * ] repeat” almost twice as slow as “[ * . true ] whileTrue” ?

#repeat isn’t optimized by the compiler like #whileTrue is. I don’t know if there is a reason for this, but most every other Smalltalk (Squeak, VW, & Dolphin) optimize the #repeat method.

John Brant

On Mon, Aug 15, 2016 at 12:54 AM, John Brant <[hidden email]> wrote:

> On Aug 14, 2016, at 4:42 PM, Henrik Nergaard <[hidden email]> wrote:
>
> Hi,
>
> Why  is “[ * ] repeat” almost twice as slow as “[ * . true ] whileTrue” ?

#repeat isn’t optimized by the compiler like #whileTrue is. I don’t know if there is a reason for this, but most every other Smalltalk (Squeak, VW, & Dolphin) optimize the #repeat method.

On Squeak it's optimized by default too.

 

I had an intern adding that as a bytecode compiler option and make the decompiler compliant with this. One needs to check if everything still works fine but it can be enabled. Something like: <compilerOptions: + inlineRepeat> should already work.

I think the idea was to keep limited the number of inlined messages, hence that one is not inlined by default. #timesRepeat: is not inlined either in Pharo. But then where's the limit between what you inline and what you don't... 

John Brant