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guile/oop/goops/compile.scm
Andy Wingo 5487977b1b runtime byte compilation of goops methods, whooooo
* ice-9/boot-9.scm (make-modules-in): Change to make sure that we are
  making modules in modules; that is, that a global binding of `compile'
  doesn't prevent a module from importing a submodule named `compile'.
  (resolve-module): Clean up a bit, and serialize the logic.

* libguile/objects.c (scm_mcache_lookup_cmethod, scm_apply_generic):
* libguile/eval.i.c (CEVAL): Now that cmethod entries can have a program
  as their tail instead of a memoized proc, we have to change the halting
  condition on the method cache search, in both places: the one that's
  inlined into eval.i.c and the one in objects.c. If the cmethod isn't a
  pair, apply it.

* libguile/goops.c (make): In the `make' procedure that's used before
  GOOPS is booted, bind #:formals, #:body, and #:compile-env on methods.

* oop/goops/compile.scm (compute-entry-with-cmethod): There was a
  terrible trick here that involved putting a dummy pair in the cache,
  then modifying it in place with the result of memoization. The note
  claimed that this was to cut recursion short, or something. I can't see
  how it could recurse, given that `methods' is changing each time. Also,
  the pair trick doesn't work with byte-compiled methods. So, remove it.
  (compile-method): Dispatch to the appropriate method compiler, based on
  whether the method was defined with the interpreter or with the
  compiler.
  (make-next-method): New function, generically computes a `next-method'
  procedure, though the caller has to supply the arguments.
  (compile-method/vm): Exciting method byte compiler!
  (make-make-next-method/memoizer, compile-method/memoizer): Add the
  /memoizer suffix, and move all this code to the bottom of the file.
2008-10-30 13:42:40 +01:00

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;;;; Copyright (C) 1999, 2001, 2006 Free Software Foundation, Inc.
;;;;
;;;; This library is free software; you can redistribute it and/or
;;;; modify it under the terms of the GNU Lesser General Public
;;;; License as published by the Free Software Foundation; either
;;;; version 2.1 of the License, or (at your option) any later version.
;;;;
;;;; This library is distributed in the hope that it will be useful,
;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
;;;; Lesser General Public License for more details.
;;;;
;;;; You should have received a copy of the GNU Lesser General Public
;;;; License along with this library; if not, write to the Free Software
;;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
;;;;
(define-module (oop goops compile)
:use-module (oop goops)
:use-module (oop goops util)
:export (compute-cmethod compute-entry-with-cmethod
compile-method cmethod-code cmethod-environment)
:no-backtrace
)
;;;
;;; Method entries
;;;
(define code-table-lookup
(letrec ((check-entry (lambda (entry types)
(if (null? types)
(and (not (struct? (car entry)))
entry)
(and (eq? (car entry) (car types))
(check-entry (cdr entry) (cdr types)))))))
(lambda (code-table types)
(cond ((null? code-table) #f)
((check-entry (car code-table) types)
=> (lambda (cmethod)
(cons (car code-table) cmethod)))
(else (code-table-lookup (cdr code-table) types))))))
(define (compute-entry-with-cmethod methods types)
(or (code-table-lookup (slot-ref (car methods) 'code-table) types)
(let* ((method (car methods))
(cmethod (compile-method methods types))
(entry (append types cmethod)))
(slot-set! method 'code-table
(cons entry (slot-ref method 'code-table)))
(cons entry cmethod))))
(define (compute-cmethod methods types)
(cdr (compute-entry-with-cmethod methods types)))
;;;
;;; Next methods
;;;
;;; Temporary solution---return #f if x doesn't refer to `next-method'.
(define (next-method? x)
(and (pair? x)
(or (eq? (car x) 'next-method)
(next-method? (car x))
(next-method? (cdr x)))))
(define (make-final-make-next-method method)
(lambda default-args
(lambda args
(@apply method (if (null? args) default-args args)))))
(define (make-final-make-no-next-method gf)
(lambda default-args
(lambda args
(no-next-method gf (if (null? args) default-args args)))))
;;;
;;; Method compilation
;;;
;;; So, for the reader: there basic idea is that, given that the
;;; semantics of `next-method' depend on the concrete types being
;;; dispatched, why not compile a specific procedure to handle each type
;;; combination that we see at runtime. There are two compilation
;;; strategies implemented: one for the memoizer, and one for the VM
;;; compiler.
;;;
;;; In theory we can do much better than a bytecode compilation, because
;;; we know the *exact* types of the arguments. It's ideal for native
;;; compilation. A task for the future.
;;;
;;; I think this whole generic application mess would benefit from a
;;; strict MOP.
(define (compile-method methods types)
(if (slot-ref (car methods) 'compile-env)
(compile-method/vm methods types)
(compile-method/memoizer methods types)))
(define (make-next-method gf methods types)
(if (null? methods)
(lambda args (no-next-method gf args))
(let ((cmethod (compute-cmethod methods types)))
(if (pair? cmethod)
;; if it's a pair, the next-method is interpreted
(local-eval (cons 'lambda (cmethod-code cmethod))
(cmethod-environment cmethod))
;; otherwise a normal procedure
cmethod))))
(define (compile-method/vm methods types)
(let* ((program-external (@ (system vm program) program-external))
(formals (slot-ref (car methods) 'formals))
(body (slot-ref (car methods) 'body)))
(cond
((not (next-method? body))
;; just one method to call -- in the future we could compile this
;; based on the types that we see, but for now just return the
;; method procedure (which is vm-compiled already)
(method-procedure (car methods)))
;; (and-map (lambda (m) (null? (slot-ref m 'compile-env))) methods)
;; many methods, but with no lexical bindings: can inline, in theory.
;;
;; modules complicate this though, the different method bodies only
;; make sense in the contexts of their modules. so while we could
;; expand this to a big letrec, there wouldn't be real inlining.
(else
(let* ((next-method-sym (gensym " next-method"))
(method (car methods))
(cmethod (compile
`(let ((,next-method-sym #f))
(lambda ,formals
(let ((next-method
(lambda args
(if (null? args)
,(if (list? formals)
`(,next-method-sym ,@formals)
`(apply
,next-method-sym
,@(improper->proper formals)))
(apply ,next-method-sym args)))))
,@body)))
(slot-ref method 'compile-env))))
(list-set! (program-external cmethod) 0
(make-next-method (method-generic-function method)
(cdr methods)
types))
cmethod)))))
;;;
;;; Compiling methods for the memoizer
;;;
(define source-formals cadr)
(define source-body cddr)
(define cmethod-code cdr)
(define cmethod-environment car)
(define %tag-body
(nested-ref the-root-module '(app modules oop goops %tag-body)))
;;; An exegetical note: the strategy here seems to be to (a) only put in
;;; next-method if it's referenced in the code; (b) memoize the lookup
;;; lazily, when `next-method' is first called.
(define (make-make-next-method/memoizer vcell gf methods types)
(lambda default-args
(lambda args
(if (null? methods)
(begin
(set-cdr! vcell (make-final-make-no-next-method gf))
(no-next-method gf (if (null? args) default-args args)))
(let* ((cmethod (compute-cmethod methods types))
(method (local-eval (cons 'lambda (cmethod-code cmethod))
(cmethod-environment cmethod))))
(set-cdr! vcell (make-final-make-next-method method))
(@apply method (if (null? args) default-args args)))))))
(define (compile-method/memoizer methods types)
(let* ((proc (method-procedure (car methods)))
;; XXX - procedure-source can not be guaranteed to be
;; reliable or efficient
(src (procedure-source proc))
(formals (source-formals src))
(body (source-body src)))
(if (next-method? body)
(let ((vcell (cons 'goops:make-next-method #f)))
(set-cdr! vcell
(make-make-next-method/memoizer
vcell
(method-generic-function (car methods))
(cdr methods) types))
;;*fixme*
`(,(cons vcell (procedure-environment proc))
,formals
;;*fixme* Only do this on source where next-method can't be inlined
(let ((next-method ,(if (list? formals)
`(goops:make-next-method ,@formals)
`(apply goops:make-next-method
,@(improper->proper formals)))))
,@body)))
(cons (procedure-environment proc)
(cons formals
(%tag-body body)))
)))