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New pass to avoid free variable creation for self-recursion

* module/language/cps/self-references.scm: New pass, avoids the need for
  self-recursion to allocate free variables.

* module/Makefile.am:
* module/language/cps/compile-bytecode.scm: Wire up the new pass.
This commit is contained in:
Andy Wingo 2014-04-08 21:41:42 +02:00
parent 1d8b325994
commit c4a209b96f
3 changed files with 82 additions and 0 deletions

View file

@ -133,6 +133,7 @@ CPS_LANG_SOURCES = \
language/cps/prune-top-level-scopes.scm \
language/cps/reify-primitives.scm \
language/cps/renumber.scm \
language/cps/self-references.scm \
language/cps/slot-allocation.scm \
language/cps/simplify.scm \
language/cps/spec.scm \

View file

@ -40,6 +40,7 @@
#:use-module (language cps prune-top-level-scopes)
#:use-module (language cps reify-primitives)
#:use-module (language cps renumber)
#:use-module (language cps self-references)
#:use-module (language cps simplify)
#:use-module (language cps slot-allocation)
#:use-module (language cps specialize-primcalls)
@ -72,6 +73,7 @@
(exp (run-pass exp elide-values #:elide-values? #t))
(exp (run-pass exp prune-bailouts #:prune-bailouts? #t))
(exp (run-pass exp eliminate-common-subexpressions #:cse? #t))
(exp (run-pass exp resolve-self-references #:resolve-self-references? #t))
(exp (run-pass exp eliminate-dead-code #:eliminate-dead-code? #t))
(exp (run-pass exp simplify #:simplify? #t)))
;; Passes that are needed:

View file

@ -0,0 +1,79 @@
;;; Continuation-passing style (CPS) intermediate language (IL)
;; Copyright (C) 2013, 2014 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 3 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
;;; Commentary:
;;;
;;; A pass that prunes successors of expressions that bail out.
;;;
;;; Code:
(define-module (language cps self-references)
#:use-module (ice-9 match)
#:use-module (language cps)
#:export (resolve-self-references))
(define* (resolve-self-references fun #:optional (env '()))
(define (subst var)
(or (assq-ref env var) var))
(define (visit-cont cont)
(rewrite-cps-cont cont
(($ $cont label ($ $kargs names vars body))
(label ($kargs names vars ,(visit-term body))))
(($ $cont label ($ $kentry self tail clause))
(label ($kentry self ,tail
,(and clause (visit-cont clause)))))
(($ $cont label ($ $kclause arity body alternate))
(label ($kclause ,arity ,(visit-cont body)
,(and alternate (visit-cont alternate)))))
(_ ,cont)))
(define (visit-term term)
(rewrite-cps-term term
(($ $letrec names vars funs body)
($letrec names vars (map visit-recursive-fun funs vars)
,(visit-term body)))
(($ $letk conts body)
($letk ,(map visit-cont conts)
,(visit-term body)))
(($ $continue k src exp)
($continue k src ,(visit-exp exp)))))
(define (visit-exp exp)
(rewrite-cps-exp exp
((or ($ $void) ($ $const) ($ $prim)) ,exp)
(($ $fun) ,(resolve-self-references exp env))
(($ $call proc args)
($call (subst proc) ,(map subst args)))
(($ $callk k proc args)
($callk k (subst proc) ,(map subst args)))
(($ $primcall name args)
($primcall name ,(map subst args)))
(($ $values args)
($values ,(map subst args)))
(($ $prompt escape? tag handler)
($prompt escape? (subst tag) handler))))
(define (visit-recursive-fun fun var)
(match fun
(($ $fun src meta free (and cont ($ $cont _ ($ $kentry self))))
(resolve-self-references fun (acons var self env)))))
(rewrite-cps-exp fun
(($ $fun src meta free cont)
($fun src meta (map subst free) ,(visit-cont cont)))))