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guile/module/language/cps/elide-values.scm
Andy Wingo 6e422a3599 Source information goes on the $continue, not the $cont.
* module/language/cps.scm ($continue, $cont): Put source information on
  the $continue, not on the $cont.  Otherwise it is difficult for CPS
  conversion to preserve source information.
  ($fun): Add a src member to $fun.  Otherwise we might miss the source
  info for the start of the function.

* .dir-locals.el:
* module/language/cps/arities.scm:
* module/language/cps/closure-conversion.scm:
* module/language/cps/compile-rtl.scm:
* module/language/cps/constructors.scm:
* module/language/cps/contification.scm:
* module/language/cps/dfg.scm:
* module/language/cps/elide-values.scm:
* module/language/cps/reify-primitives.scm:
* module/language/cps/slot-allocation.scm:
* module/language/cps/verify.scm:
* module/language/tree-il/compile-cps.scm: Update the whole CPS world
  for this change.
2013-11-07 10:32:21 +01:00

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3.3 KiB
Scheme

;;; Continuation-passing style (CPS) intermediate language (IL)
;; Copyright (C) 2013 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:
;;;
;;; Primcalls that don't correspond to VM instructions are treated as if
;;; they are calls, and indeed the later reify-primitives pass turns
;;; them into calls. Because no return arity checking is done for these
;;; primitives, if a later optimization pass simplifies the primcall to
;;; an RTL operation, the tail of the simplification has to be a
;;; primcall to 'values. Most of these primcalls can be elided, and
;;; that is the job of this pass.
;;;
;;; Code:
(define-module (language cps elide-values)
#:use-module (ice-9 match)
#:use-module (srfi srfi-26)
#:use-module (language cps)
#:use-module (language cps dfg)
#:export (elide-values))
(define (elide-values fun)
(let ((conts (build-local-cont-table
(match fun (($ $fun src meta free body) body)))))
(define (visit-cont cont)
(rewrite-cps-cont cont
(($ $cont sym ($ $kargs names syms body))
(sym ($kargs names syms ,(visit-term body))))
(($ $cont sym ($ $kentry self tail clauses))
(sym ($kentry self ,tail ,(map visit-cont clauses))))
(($ $cont sym ($ $kclause arity body))
(sym ($kclause ,arity ,(visit-cont body))))
(($ $cont)
,cont)))
(define (visit-term term)
(rewrite-cps-term term
(($ $letk conts body)
($letk ,(map visit-cont conts)
,(visit-term body)))
(($ $letrec names syms funs body)
($letrec names syms (map elide-values funs)
,(visit-term body)))
(($ $continue k src ($ $primcall 'values vals))
,(rewrite-cps-term (lookup-cont k conts)
(($ $ktail)
($continue k src ($values vals)))
(($ $ktrunc ($ $arity req () rest () #f) kargs)
,(if (or rest (< (length vals) (length req)))
term
(let ((vals (list-head vals (length req))))
(build-cps-term
($continue kargs src ($values vals))))))
(($ $kargs args)
,(if (< (length vals) (length args))
term
(let ((vals (list-head vals (length args))))
(build-cps-term
($continue k src ($values vals))))))))
(($ $continue k src (and fun ($ $fun)))
($continue k src ,(elide-values fun)))
(($ $continue)
,term)))
(rewrite-cps-exp fun
(($ $fun src meta free body)
($fun src meta free ,(visit-cont body))))))