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;;; Continuation-passing style (CPS) intermediate language (IL)
;; Copyright (C) 2013, 2014, 2015 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:
;;;
;;; Some bytecode operations can encode an immediate as an operand.
;;; This pass tranforms generic primcalls to these specialized
;;; primcalls, if possible.
;;;
;;; Code:
(define-module (language cps specialize-primcalls)
#:use-module (ice-9 match)
#:use-module (language cps)
#:use-module (language cps dfg)
#:export (specialize-primcalls))
(define (specialize-primcalls fun)
(let ((dfg (compute-dfg fun #:global? #t)))
(with-fresh-name-state-from-dfg dfg
(define (immediate-u8? sym)
(call-with-values (lambda () (find-constant-value sym dfg))
(lambda (has-const? val)
(and has-const? (integer? val) (exact? val) (<= 0 val 255)))))
(define (visit-cont cont)
(rewrite-cps-cont cont
(($ $cont sym ($ $kargs names syms body))
(sym ($kargs names syms ,(visit-term body))))
(($ $cont sym ($ $kfun src meta self tail clause))
(sym ($kfun src meta self ,tail
,(and clause (visit-cont clause)))))
(($ $cont sym ($ $kclause arity body alternate))
(sym ($kclause ,arity ,(visit-cont body)
,(and alternate (visit-cont alternate)))))
(($ $cont)
,cont)))
(define (visit-term term)
(rewrite-cps-term term
(($ $letk conts body)
($letk ,(map visit-cont conts)
,(visit-term body)))
(($ $continue k src (and fun ($ $fun)))
($continue k src ,(visit-fun fun)))
(($ $continue k src ($ $rec names syms funs))
($continue k src ($rec names syms (map visit-fun funs))))
(($ $continue k src ($ $primcall name args))
,(visit-primcall k src name args))
(($ $continue)
,term)))
(define (visit-primcall k src name args)
;; If we introduce a VM op from a primcall without a VM op, we
;; will need to ensure that the return arity matches. Rely on the
;; elide-values pass to clean up.
(define-syntax-rule (adapt-void exp)
(let-fresh (k* kvoid) (val)
(build-cps-term
($letk ((k* ($kargs ('val) (val)
($continue k src ($primcall 'values (val)))))
(kvoid ($kargs () ()
($continue k* src ($const *unspecified*)))))
($continue kvoid src exp)))))
(define-syntax-rule (adapt-val exp)
(let-fresh (k*) (val)
(build-cps-term
($letk ((k* ($kargs ('val) (val)
($continue k src ($primcall 'values (val))))))
($continue k* src exp)))))
(match (cons name args)
(('make-vector (? immediate-u8? n) init)
(adapt-val ($primcall 'make-vector/immediate (n init))))
(('vector-ref v (? immediate-u8? n))
(build-cps-term
($continue k src ($primcall 'vector-ref/immediate (v n)))))
(('vector-set! v (? immediate-u8? n) x)
(build-cps-term
($continue k src ($primcall 'vector-set!/immediate (v n x)))))
(('allocate-struct v (? immediate-u8? n))
(adapt-val ($primcall 'allocate-struct/immediate (v n))))
(('struct-ref s (? immediate-u8? n))
(adapt-val ($primcall 'struct-ref/immediate (s n))))
(('struct-set! s (? immediate-u8? n) x)
(build-cps-term
($continue k src ($primcall 'struct-set!/immediate (s n x)))))
(_
(build-cps-term ($continue k src ($primcall name args))))))
(define (visit-fun fun)
(rewrite-cps-exp fun
(($ $fun body)
($fun ,(visit-cont body)))))
(visit-cont fun))))
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