Mercurial > urweb

annotate src/mono_reduce.sml @ 313:e0ed0d4dabc9

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Termination checking
author Adam Chlipala <adamc@hcoop.net>
date Tue, 09 Sep 2008 11:46:33 -0400
parents 52d4c60518d4
children 04ebfe929a98
rev   line source
adamc@133 1 (* Copyright (c) 2008, Adam Chlipala
adamc@133 2 * All rights reserved.
adamc@133 3 *
adamc@133 4 * Redistribution and use in source and binary forms, with or without
adamc@133 5 * modification, are permitted provided that the following conditions are met:
adamc@133 6 *
adamc@133 7 * - Redistributions of source code must retain the above copyright notice,
adamc@133 8 * this list of conditions and the following disclaimer.
adamc@133 9 * - Redistributions in binary form must reproduce the above copyright notice,
adamc@133 10 * this list of conditions and the following disclaimer in the documentation
adamc@133 11 * and/or other materials provided with the distribution.
adamc@133 12 * - The names of contributors may not be used to endorse or promote products
adamc@133 13 * derived from this software without specific prior written permission.
adamc@133 14 *
adamc@133 15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
adamc@133 16 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
adamc@133 17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
adamc@133 18 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
adamc@133 19 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
adamc@133 20 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
adamc@133 21 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
adamc@133 22 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
adamc@133 23 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
adamc@133 24 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
adamc@133 25 * POSSIBILITY OF SUCH DAMAGE.
adamc@133 26 *)
adamc@133 27
adamc@133 28 (* Simplify a Mono program algebraically *)
adamc@133 29
adamc@133 30 structure MonoReduce :> MONO_REDUCE = struct
adamc@133 31
adamc@133 32 open Mono
adamc@133 33
adamc@133 34 structure E = MonoEnv
adamc@133 35 structure U = MonoUtil
adamc@133 36
adamc@133 37
adamc@252 38 fun impure (e, _) =
adamc@252 39 case e of
adamc@252 40 EWrite _ => true
adamc@252 41 | EQuery _ => true
adamc@307 42 | EDml _ => true
adamc@252 43 | EAbs _ => false
adamc@252 44
adamc@252 45 | EPrim _ => false
adamc@252 46 | ERel _ => false
adamc@252 47 | ENamed _ => false
adamc@252 48 | ECon (_, _, eo) => (case eo of NONE => false | SOME e => impure e)
adamc@297 49 | ENone _ => false
adamc@290 50 | ESome (_, e) => impure e
adamc@252 51 | EFfi _ => false
adamc@252 52 | EFfiApp _ => false
adamc@252 53 | EApp ((EFfi _, _), _) => false
adamc@252 54 | EApp _ => true
adamc@252 55
adamc@252 56 | ERecord xes => List.exists (fn (_, e, _) => impure e) xes
adamc@252 57 | EField (e, _) => impure e
adamc@252 58
adamc@252 59 | ECase (e, pes, _) => impure e orelse List.exists (fn (_, e) => impure e) pes
adamc@252 60
adamc@283 61 | EError (e, _) => impure e
adamc@283 62
adamc@252 63 | EStrcat (e1, e2) => impure e1 orelse impure e2
adamc@252 64
adamc@252 65 | ESeq (e1, e2) => impure e1 orelse impure e2
adamc@252 66 | ELet (_, _, e1, e2) => impure e1 orelse impure e2
adamc@252 67
adamc@252 68 | EClosure (_, es) => List.exists impure es
adamc@252 69
adamc@252 70
adamc@252 71 val liftExpInExp = Monoize.liftExpInExp
adamc@252 72
adamc@252 73 val subExpInExp' =
adamc@133 74 U.Exp.mapB {typ = fn t => t,
adamc@133 75 exp = fn (xn, rep) => fn e =>
adamc@133 76 case e of
adamc@133 77 ERel xn' =>
adamc@133 78 (case Int.compare (xn', xn) of
adamc@133 79 EQUAL => #1 rep
adamc@133 80 | GREATER=> ERel (xn' - 1)
adamc@133 81 | LESS => e)
adamc@133 82 | _ => e,
adamc@133 83 bind = fn ((xn, rep), U.Exp.RelE _) => (xn+1, liftExpInExp 0 rep)
adamc@133 84 | (ctx, _) => ctx}
adamc@133 85
adamc@252 86 fun subExpInExp (n, e1) e2 =
adamc@252 87 let
adamc@252 88 val r = subExpInExp' (n, e1) e2
adamc@252 89 in
adamc@252 90 (*Print.prefaces "subExpInExp" [("e1", MonoPrint.p_exp MonoEnv.empty e1),
adamc@252 91 ("e2", MonoPrint.p_exp MonoEnv.empty e2),
adamc@252 92 ("r", MonoPrint.p_exp MonoEnv.empty r)];*)
adamc@252 93 r
adamc@252 94 end
adamc@133 95
adamc@133 96 fun typ c = c
adamc@133 97
adamc@258 98 datatype result = Yes of E.env | No | Maybe
adamc@258 99
adamc@183 100 fun match (env, p : pat, e : exp) =
adamc@183 101 case (#1 p, #1 e) of
adamc@258 102 (PWild, _) => Yes env
adamc@258 103 | (PVar (x, t), _) => Yes (E.pushERel env x t (SOME e))
adamc@183 104
adamc@280 105 | (PPrim (Prim.String s), EStrcat ((EPrim (Prim.String s'), _), _)) =>
adamc@280 106 if String.isPrefix s' s then
adamc@280 107 Maybe
adamc@280 108 else
adamc@280 109 No
adamc@280 110
adamc@183 111 | (PPrim p, EPrim p') =>
adamc@183 112 if Prim.equal (p, p') then
adamc@258 113 Yes env
adamc@183 114 else
adamc@258 115 No
adamc@183 116
adamc@188 117 | (PCon (_, PConVar n1, NONE), ECon (_, PConVar n2, NONE)) =>
adamc@183 118 if n1 = n2 then
adamc@258 119 Yes env
adamc@183 120 else
adamc@258 121 No
adamc@183 122
adamc@188 123 | (PCon (_, PConVar n1, SOME p), ECon (_, PConVar n2, SOME e)) =>
adamc@183 124 if n1 = n2 then
adamc@183 125 match (env, p, e)
adamc@183 126 else
adamc@258 127 No
adamc@183 128
adamc@188 129 | (PCon (_, PConFfi {mod = m1, con = con1, ...}, NONE), ECon (_, PConFfi {mod = m2, con = con2, ...}, NONE)) =>
adamc@185 130 if m1 = m2 andalso con1 = con2 then
adamc@258 131 Yes env
adamc@185 132 else
adamc@258 133 No
adamc@185 134
adamc@188 135 | (PCon (_, PConFfi {mod = m1, con = con1, ...}, SOME ep), ECon (_, PConFfi {mod = m2, con = con2, ...}, SOME e)) =>
adamc@185 136 if m1 = m2 andalso con1 = con2 then
adamc@185 137 match (env, p, e)
adamc@185 138 else
adamc@258 139 No
adamc@185 140
adamc@183 141 | (PRecord xps, ERecord xes) =>
adamc@183 142 let
adamc@183 143 fun consider (xps, env) =
adamc@183 144 case xps of
adamc@258 145 [] => Yes env
adamc@183 146 | (x, p, _) :: rest =>
adamc@183 147 case List.find (fn (x', _, _) => x' = x) xes of
adamc@258 148 NONE => No
adamc@183 149 | SOME (_, e, _) =>
adamc@183 150 case match (env, p, e) of
adamc@258 151 No => No
adamc@258 152 | Maybe => Maybe
adamc@258 153 | Yes env => consider (rest, env)
adamc@183 154 in
adamc@183 155 consider (xps, env)
adamc@183 156 end
adamc@183 157
adamc@258 158 | _ => Maybe
adamc@183 159
adamc@133 160 fun exp env e =
adamc@133 161 case e of
adamc@183 162 ERel n =>
adamc@183 163 (case E.lookupERel env n of
adamc@183 164 (_, _, SOME e') => #1 e'
adamc@183 165 | _ => e)
adamc@183 166 | ENamed n =>
adamc@133 167 (case E.lookupENamed env n of
adamc@133 168 (_, _, SOME e', _) => #1 e'
adamc@133 169 | _ => e)
adamc@133 170
adamc@252 171 | EApp ((EAbs (x, t, _, e1), loc), e2) =>
adamc@252 172 ((*Print.prefaces "Considering" [("e1", MonoPrint.p_exp env e1),
adamc@252 173 ("e2", MonoPrint.p_exp env e2)];*)
adamc@252 174 if impure e2 then
adamc@252 175 #1 (reduceExp env (ELet (x, t, e2, e1), loc))
adamc@252 176 else
adamc@252 177 #1 (reduceExp env (subExpInExp (0, e2) e1)))
adamc@133 178
adamc@184 179 | ECase (disc, pes, _) =>
adamc@258 180 let
adamc@258 181 fun search pes =
adamc@258 182 case pes of
adamc@258 183 [] => e
adamc@258 184 | (p, body) :: pes =>
adamc@258 185 case match (env, p, disc) of
adamc@258 186 No => search pes
adamc@258 187 | Maybe => e
adamc@258 188 | Yes env => #1 (reduceExp env body)
adamc@258 189 in
adamc@258 190 search pes
adamc@258 191 end
adamc@183 192
adamc@252 193 | EField ((ERecord xes, _), x) =>
adamc@252 194 (case List.find (fn (x', _, _) => x' = x) xes of
adamc@252 195 SOME (_, e, _) => #1 e
adamc@252 196 | NONE => e)
adamc@252 197
adamc@252 198 | ELet (x1, t1, (ELet (x2, t2, e1, b1), loc), b2) =>
adamc@252 199 let
adamc@252 200 val e' = (ELet (x2, t2, e1,
adamc@252 201 (ELet (x1, t1, b1,
adamc@252 202 liftExpInExp 1 b2), loc)), loc)
adamc@252 203 in
adamc@253 204 (*Print.prefaces "ELet commute" [("e", MonoPrint.p_exp env (e, loc)),
adamc@253 205 ("e'", MonoPrint.p_exp env e')];*)
adamc@252 206 #1 (reduceExp env e')
adamc@252 207 end
adamc@252 208 | EApp ((ELet (x, t, e, b), loc), e') =>
adamc@252 209 #1 (reduceExp env (ELet (x, t, e,
adamc@252 210 (EApp (b, liftExpInExp 0 e'), loc)), loc))
adamc@252 211 | ELet (x, t, e', b) =>
adamc@252 212 if impure e' then
adamc@252 213 e
adamc@252 214 else
adamc@252 215 #1 (reduceExp env (subExpInExp (0, e') b))
adamc@252 216
adamc@268 217 | EStrcat ((EPrim (Prim.String s1), _), (EPrim (Prim.String s2), _)) =>
adamc@268 218 EPrim (Prim.String (s1 ^ s2))
adamc@268 219
adamc@133 220 | _ => e
adamc@133 221
adamc@252 222 and bind (env, b) =
adamc@252 223 case b of
adamc@252 224 U.Decl.Datatype (x, n, xncs) => E.pushDatatype env x n xncs
adamc@252 225 | U.Decl.RelE (x, t) => E.pushERel env x t NONE
adamc@252 226 | U.Decl.NamedE (x, n, t, eo, s) => E.pushENamed env x n t (Option.map (reduceExp env) eo) s
adamc@252 227
adamc@133 228 and reduceExp env = U.Exp.mapB {typ = typ, exp = exp, bind = bind} env
adamc@133 229
adamc@133 230 fun decl env d = d
adamc@133 231
adamc@133 232 val reduce = U.File.mapB {typ = typ, exp = exp, decl = decl, bind = bind} E.empty
adamc@133 233
adamc@133 234 end