/usr/share/acl2-6.3/books/misc/fast-coerce.lisp is in acl2-books-source 6.3-5.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 | ; fast-coerce.lisp
; Copyright (C) 2008 by Jared Davis <jared@cs.utexas.edu>
;
; This program is free software; you can redistribute it and/or modify it under
; the terms of the GNU General Public License as published by the Free Software
; Foundation; either version 2 of the License, or (at your option) any later
; version. This program 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 General Public License for
; more details. You should have received a copy of the GNU General Public
; License along with this program; if not, write to the Free Software
; Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
(in-package "ACL2")
; This is a sometimes-faster version of coerce.
;
; - It is the same as ACL2's regular coerce when converting character lists
; into strings.
;
; - It is sometimes faster when converting strings into character lists.
;
; "Fast-coerce is _____ than regular coerce"
;
; - Allegro: negligibly faster
; - Clisp: negligibly slower
; - GCL: 50-60% faster
; - CMUCL: 40% faster & uses 30% less memory
; - SBCL: 50% faster & uses 8% less memory
; - Old CCL: 90% faster & uses 56% less memory
; - New CCL: 18% slower
;
; We would like to tailor the :exec part of the definition to fit the Lisp we
; are using via features, but we think this would break the ability to share
; certificates across Lisps. Ugh. For now we are just going to leave it as
; is, and say don't use it if your primary environment is the new version of
; CCL.
;
; Ideally we should get rid of this file and simply improve each Lisp.
;
; On Nemesis. (32-bit) -- fast-coerce -------- coerce ------
;
; /p/bin/acl2 10.6s 27s
;
; /p/bin/acl2-allegro 46.4s 48.5s
; 1.040 GB 1.040 GB
;
; /p/bin/acl2-cmucl 10.3s 17.1s
; 1.040 GB 1.440 GB
;
; /p/bin/acl2-clisp 44.35s 42.6s
; 1.040 GB 1.040 GB
;
; On Lhug-3. (64-bit) --- fast-coerce -------- coerce ------
;
;
; /p/bin/acl2-gcl 18.8s 39.7s
;
; /p/bin/acl2-openmcl 5.5s 64s (OLDER VERSION)
; 2.080 GB 4.64 GB
;
; /p/bin/acl2-sbcl 5.6s 10.94s
; 2.080 GB 2.240 GB
;
;
; On FV-1 (64-bit) --- fast-coerce -------- coerce ------
;
; acl2-ccl 4.96s 4.07s (NEW VERSION)
; 2.080 GB 2.080 GB
#||
(time$ (loop for i fixnum from 1 to 10000000 do
(coerce "Hello, World!" 'list)))
(time$ (loop for i fixnum from 1 to 10000000 do
(fast-coerce "Hello, World!" 'list)))
||#
(local (include-book "arithmetic/top-with-meta" :dir :system))
(local (include-book "data-structures/list-defthms" :dir :system))
(defund fast-coerce-aux1 (x i len)
(declare (type string x)
(type (signed-byte 30) i)
(type (signed-byte 30) len)
(xargs :guard (and (stringp x)
(natp i)
(natp len)
(= len (length x))
(<= i len))
:measure (nfix (- (nfix len) (nfix i)))))
(if (mbe :logic (zp (- (nfix len) (nfix i)))
:exec (= (the-fixnum i)
(the-fixnum len)))
nil
(cons (the character
(char (the string x)
(the (signed-byte 30) i)))
(fast-coerce-aux1 x
(the-fixnum
(+ (the-fixnum 1)
(mbe :logic (nfix i)
:exec (the-fixnum i))))
(the-fixnum len)))))
(defund fast-coerce-aux2 (x i len)
(declare (type string x)
(type integer i)
(type integer len)
(xargs :guard (and (stringp x)
(natp i)
(natp len)
(= len (length x))
(<= i len))
:guard-debug t
:measure (nfix (- (nfix len) (nfix i)))))
(if (mbe :logic (zp (- (nfix len) (nfix i)))
:exec (= (the integer i) (the integer len)))
nil
(cons (char x i)
(fast-coerce-aux2 x
(+ (the integer 1)
(mbe :logic (nfix i)
:exec (the integer i)))
len))))
(local (defthm lemma
(implies (and (natp i)
(< i (len x)))
(equal (cons (nth i x)
(cdr (nthcdr i x)))
(nthcdr i x)))))
(local (defthm lemma2
(equal (nthcdr i (cdr x))
(cdr (nthcdr i x)))))
(local (defthm lemma3
(implies (and (stringp x)
(natp i)
(<= i (length x)))
(equal (fast-coerce-aux2 x i (len (coerce x 'list)))
(nthcdr i (coerce x 'list))))
:hints(("Goal"
:in-theory (enable fast-coerce-aux2)))))
(local (defthm fast-coerce-aux2-equiv
(equal (fast-coerce-aux1 x i len)
(fast-coerce-aux2 x i len))
:hints(("Goal" :in-theory (enable fast-coerce-aux2
fast-coerce-aux1)))))
(defun fast-coerce (x y)
(declare (xargs :guard (case y
(list (stringp x))
(string (character-listp x)))))
(mbe :logic (coerce x y)
:exec
;; I'd like to just use
;; (if (eq y 'list)
;; (coerce x 'list)
;; (coerce x 'string))
;; when running on CLISP or CCL, and the loop below for other Lisps. But
;; this would break certificate-compatibility, so I just leave it as is.
(if (eq y 'list)
(let ((length (length x)))
(if (< (the integer length)
(the integer 536870912))
(fast-coerce-aux1 (the string x)
(the (signed-byte 30) 0)
(the (signed-byte 30) length))
(fast-coerce-aux2 (the string x)
(the integer 0)
(the integer length))))
(coerce x y))))
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