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;;; Continuation-passing style (CPS) intermediate language (IL)
;; Copyright (C) 2013-2015, 2017-2018 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 utils)
#:use-module (language cps intmap)
#:export (specialize-primcalls))
(define (compute-defining-expressions conts)
(define (meet-defining-expressions old new)
;; If there are multiple definitions and they are different, punt
;; and record #f.
(if (equal? old new)
old
#f))
(persistent-intmap
(intmap-fold (lambda (label cont defs)
(match cont
(($ $kargs _ _ ($ $continue k src exp))
(match (intmap-ref conts k)
(($ $kargs (_) (var))
(intmap-add! defs var exp meet-defining-expressions))
(_ defs)))
(_ defs)))
conts
empty-intmap)))
(define (compute-constant-values conts)
(let ((defs (compute-defining-expressions conts)))
(persistent-intmap
(intmap-fold
(lambda (var exp out)
(match exp
(($ $primcall (or 'load-f64 'load-u64 'load-s64) val ())
(intmap-add! out var val))
;; Punch through type conversions to allow uadd to specialize
;; to uadd/immediate.
(($ $primcall 'scm->f64 #f (val))
(let ((f64 (intmap-ref out val (lambda (_) #f))))
(if (and f64 (number? f64) (inexact? f64) (real? f64))
(intmap-add! out var f64)
out)))
(($ $primcall (or 'scm->u64 'scm->u64/truncate) #f (val))
(let ((u64 (intmap-ref out val (lambda (_) #f))))
(if (and u64 (number? u64) (exact-integer? u64)
(<= 0 u64 #xffffFFFFffffFFFF))
(intmap-add! out var u64)
out)))
(($ $primcall 'scm->s64 #f (val))
(let ((s64 (intmap-ref out val (lambda (_) #f))))
(if (and s64 (number? s64) (exact-integer? s64)
(<= (- #x8000000000000000) s64 #x7fffFFFFffffFFFF))
(intmap-add! out var s64)
out)))
(_ out)))
defs
(intmap-fold (lambda (var exp out)
(match exp
(($ $const val)
(intmap-add! out var val))
(_ out)))
defs
empty-intmap)))))
(define (specialize-primcalls conts)
(let ((constants (compute-constant-values conts)))
(define (uint? var)
(let ((val (intmap-ref constants var (lambda (_) #f))))
(and (exact-integer? val) (<= 0 val))))
(define (u64? var)
(let ((val (intmap-ref constants var (lambda (_) #f))))
(and (exact-integer? val) (<= 0 val #xffffFFFFffffFFFF))))
(define (num? var)
(number? (intmap-ref constants var (lambda (_) #f))))
(define (s64? var)
(let ((val (intmap-ref constants var (lambda (_) #f))))
(and (exact-integer? val)
(<= (- #x8000000000000000) val #x7fffFFFFffffFFFF))))
(define (f64? var)
(let ((val (intmap-ref constants var (lambda (_) #f))))
(and (number? val) (inexact? val) (real? val))))
(define (specialize-primcall name param args)
(define (rename name)
(build-exp ($primcall name param args)))
(define-syntax compute-constant
(syntax-rules ()
((_ (c exp) body)
(let* ((c (intmap-ref constants c)) (c exp)) body))
((_ c body) (compute-constant (c c) body))))
(define-syntax-rule (specialize-case (pat (op c (arg ...))) ...)
(match (cons name args)
(pat
(let* ((param* (intmap-ref constants c))
(param (if param (cons param param*) param*)))
(build-exp ($primcall 'op param (arg ...)))))
...
(_ #f)))
(specialize-case
(('allocate-words (? uint? n)) (allocate-words/immediate n ()))
(('allocate-pointerless-words (? uint? n))
(allocate-pointerless-words/immediate n ()))
(('scm-ref o (? uint? i)) (scm-ref/immediate i (o)))
(('scm-set! o (? uint? i) x) (scm-set!/immediate i (o x)))
;; Assume (tail-)pointer-ref/immediate can always be emitted directly.
(('word-ref o (? uint? i)) (word-ref/immediate i (o)))
(('word-set! o (? uint? i) x) (word-set!/immediate i (o x)))
(('add x (? num? y)) (add/immediate y (x)))
(('add (? num? y) x) (add/immediate y (x)))
(('sub x (? num? y)) (sub/immediate y (x)))
(('uadd x (? uint? y)) (uadd/immediate y (x)))
(('uadd (? uint? y) x) (uadd/immediate y (x)))
(('usub x (? uint? y)) (usub/immediate y (x)))
(('umul x (? uint? y)) (umul/immediate y (x)))
(('umul (? uint? y) x) (umul/immediate y (x)))
(('scm->f64 (? f64? var)) (load-f64 var ()))
(('scm->u64 (? u64? var)) (load-u64 var ()))
(('scm->u64/truncate (? u64? var)) (load-u64 var ()))
(('scm->s64 (? s64? var)) (load-s64 var ()))
(('untag-fixnum (? s64? var)) (load-s64 var ()))
(('untag-char (? u64? var)) (load-u64 var ()))
;; FIXME: add support for tagging immediate chars
;; (('tag-char (? u64? var)) (load-const var ()))
))
(intmap-map
(lambda (label cont)
(match cont
(($ $kargs names vars ($ $continue k src ($ $primcall name param args)))
(let ((exp* (specialize-primcall name param args)))
(if exp*
(build-cont
($kargs names vars ($continue k src ,exp*)))
cont)))
(_ cont)))
conts)))
;;; Local Variables:
;;; eval: (put 'specialize-case 'scheme-indent-function 0)
;;; End:
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