At 09:34 PM 8/10/00 -0400, Bradley M. Kuhn wrote:
>Three notes on the Syntax tree (which I would probably call Intermediate
>Representation, or IR, but the name is irrelevant :).
Yep. It's more a MI, with bytecodes being an LI. (And both are IRs) I've
been browsing through compiler design books, as if you couldn't tell... :)
>First, I believe that it is completely reasonable and probably useful to
>consider allowing an optimization step that operates directly on the IR.
>Bytecodes are often harder to optimize than the IR.
Fair enough. I think we should pass the syntax tree on to the optimzier in
addition to the bytecode stream for just that sort of thing.
>Second, I think that it is terribly important that they format of the IR be
>well described in a document separate from the code. I am willing to help
>maintain this document, but I think it is imperative that we don't let the
>"implementation be the reference". If the code changes, the document much
>change to reflect it.
Oh, yes! Once things get a bit more solid on the language end, I expect
we'll have syntax and bytecode working groups to hammer those out and nail
'em down.
>Third, I am very glad that Dan has placed the execution engine very far from
>the IR. Whether or not we want to have an execution engine (which I tend to
>call a VM :) that works directly on the IR or one that always goes through
>bytecode, or both, I think we must keep a high wall of abstraction between
>the IR and the VM.
Bytecode is an IR too, just with a different target.
I do want that heavy wall, though. That backend could be a perl2jvm
translator, or a TIL version of the interpreter (if we don't go that way to
start), or a frontend to a 'real' compiler like GCC or the Dec compilers.
(Both gcc and the dec compilers have one backend for a whole bunch of
language front-ends. If they can front-end fortran, C++, and cobol, we
ought to be able to do it with perl...)
Dan
--------------------------------------"it's like this"-------------------
Dan Sugalski even samurai
[EMAIL PROTECTED] have teddy bears and even
teddy bears get drunk
