Igor Stasenko wrote:
> Okay, but what about reusing the arguments stack slots?

And what if there are none? There are tons of primitives returning 
complex objects (arrays, rectangles) that take no arguments.

> In most cases, when primitive generating response its:
> - already checked everything (can't fail)

Primitives can fail for other reasons than argument mismatches.

> - already evaluated results
> - arguments no more in use

> And , since primitive should return only single object, its easy to
> prove, that it requires MAXIMUM SINGLE temp value on stack, which
> needs to be remapped.

Not true either. ObjectMemory>>allocate: remaps the classOop so a depth 
of AT LEAST 2 is required even for your example. There are almost 
certainly other places that have a similar effect.

> see? its even less lines of code :)

Except that it doesn't work.

Cheers,
   - Andreas