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guile/module/language/cps/handle-interrupts.scm
Andy Wingo 0ce8a9a5e0 Improve handle-interrupts placement
* module/language/cps/handle-interrupts.scm (compute-safepoints): New
  function.
  (add-handle-interrupts): Add safepoints at backedge targets, not
  backedges.  Gives better register allocation, loop rotation, and code
  size.
2016-12-18 23:05:15 +01:00

69 lines
2.5 KiB
Scheme

;;; Continuation-passing style (CPS) intermediate language (IL)
;; Copyright (C) 2016 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 to add "handle-interrupts" primcalls before calls, loop
;;; back-edges, and returns.
;;;
;;; Code:
(define-module (language cps handle-interrupts)
#:use-module (ice-9 match)
#:use-module (language cps)
#:use-module (language cps utils)
#:use-module (language cps with-cps)
#:use-module (language cps intmap)
#:use-module (language cps intset)
#:use-module (language cps renumber)
#:export (add-handle-interrupts))
(define (compute-safepoints cps)
(define (visit-cont label cont safepoints)
(match cont
(($ $kargs names vars ($ $continue k src exp))
(let ((safepoints (if (<= k label)
(intset-add! safepoints k)
safepoints)))
(if (match exp
(($ $call) #t)
(($ $callk) #t)
(($ $values)
(match (intmap-ref cps k)
(($ $ktail) #t)
(_ #f)))
(_ #f))
(intset-add! safepoints label)
safepoints)))
(_ safepoints)))
(persistent-intset (intmap-fold visit-cont cps empty-intset)))
(define (add-handle-interrupts cps)
(define (add-safepoint label cps)
(match (intmap-ref cps label)
(($ $kargs names vars ($ $continue k src exp))
(with-cps cps
(letk k* ($kargs () () ($continue k src ,exp)))
(setk label
($kargs names vars
($continue k* src
($primcall 'handle-interrupts ()))))))))
(let* ((cps (renumber cps))
(safepoints (compute-safepoints cps)))
(with-fresh-name-state cps
(persistent-intmap (intset-fold add-safepoint safepoints cps)))))