Re: Framed Stack vs. Two Stack Architecture

moderator writes:
> [I'd think the choice of framed vs. unframed stack would depend on the
> warts of the local instruction set and whether a routine is a
> leaf. -John]


Right. But that's an optimization one can apply to framed stacks (and
something typical in JIT-compiled Smalltalk implementations too). But
Avatar enquired about the difference between "framed" (or as I take it
conventional single-stack) vs operand/control stacks. Hence I took
"Framed stack" to mean "conventional stack organization. Note that in
a Smalltalk implementation mapping between contexts and stack frames
one can still use "unframed"/leaf activations provided a full frame
can be built if needed to map to a context. e.g. the typical approach
is to not create a frame when activating a primitive method, and run
the primitive without a frame, only creating a frame if the primitive
fails.
    Likewise in our VisualWorks VM we don't create a frame for a call-out
to C, deferring building a full frame until we get a call-back.


HTMS...
--
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Eliot Miranda Smalltalk - Scene not herd

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