moved from elsewhere

On Thu, Mar 16, 2017 at 2:21 PM, tim Rowledge <tim at rowledge.org> wrote:

>
> > On 16-03-2017, at 12:56 PM, Eliot Miranda <eliot.miranda at gmail.com>
> wrote:
> >
> > IIRC, the source is encoded in the method trailer bytes.  Currently
> there's no encoding type for WideString.  But Igor's CompiledMethodTrailer
> reimplementation makes it easy to add new types.  So it should only be a
> little work to add an encoder and decoder for WideStrings.
>
> The *nicest* way to fix this would have been an actual instvar (and
> separate objects for the literals, bytecodes etc) instead of magic bytes;
> we did that at Interval (amongst other similar approaches I’ve read about)
> and it made it really easy to have simple string, a file reference, a
> database key, a URL, a compressed string etc.
>

Note that AdditionalMethodState provides another way to add inst vars.  One
can subclass AdditionalMethodState to add inst vars.  i think I even when
as far as adding the compiler support to access the inst vars
from AdditionalMethodState implicitly (rather like accessing context temps
in the lower right hand pane of the debugger).

The thing you're not mentioning is that adding the additional inst var for
bytes and literals adds significant overhead in the in terpreter.  Either
the method variable splits into a byte codes and a literals variable, both
of which have to be set on activation and return, or one adds an
indirection on each byte code and/or literal fetch, indirecting through the
method object to access byte codes and/or literals.

So for as long as we have an interpreter VM the current flat
representation, while ugly if viewed from one point of view, works really
well for the interpreter, and is quite nice when viewed from this other
point of view.


> But yes, Igor’s work makes it practical to do much the same thing albeit
> in a rather roundabout way.
>

Remember that Dan implemented eliminating sources and disassembling with
temp names by compressing the temp names to the method trailer.


> tim
> --
> tim Rowledge; tim at rowledge.org; http://www.rowledge.org/tim
> Strange OpCodes: MD: Move and Drop bits
>
>
>


-- 
_,,,^..^,,,_
best, Eliot
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