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annotate src/mono_reduce.sml @ 349:beb72f8a7218

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Expand cases where expression wildcards are allowed
author Adam Chlipala <adamc@hcoop.net>
date Sat, 04 Oct 2008 20:05:50 -0400
parents 389399d65331
children 7abb28e9d51f
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@338 43 | ENextval _ => true
adamc@252 44 | EAbs _ => false
adamc@252 45
adamc@252 46 | EPrim _ => false
adamc@252 47 | ERel _ => false
adamc@252 48 | ENamed _ => false
adamc@252 49 | ECon (_, _, eo) => (case eo of NONE => false | SOME e => impure e)
adamc@297 50 | ENone _ => false
adamc@290 51 | ESome (_, e) => impure e
adamc@252 52 | EFfi _ => false
adamc@252 53 | EFfiApp _ => false
adamc@252 54 | EApp ((EFfi _, _), _) => false
adamc@252 55 | EApp _ => true
adamc@252 56
adamc@252 57 | ERecord xes => List.exists (fn (_, e, _) => impure e) xes
adamc@252 58 | EField (e, _) => impure e
adamc@252 59
adamc@252 60 | ECase (e, pes, _) => impure e orelse List.exists (fn (_, e) => impure e) pes
adamc@252 61
adamc@283 62 | EError (e, _) => impure e
adamc@283 63
adamc@252 64 | EStrcat (e1, e2) => impure e1 orelse impure e2
adamc@252 65
adamc@252 66 | ESeq (e1, e2) => impure e1 orelse impure e2
adamc@252 67 | ELet (_, _, e1, e2) => impure e1 orelse impure e2
adamc@252 68
adamc@252 69 | EClosure (_, es) => List.exists impure es
adamc@252 70
adamc@252 71
adamc@252 72 val liftExpInExp = Monoize.liftExpInExp
adamc@252 73
adamc@252 74 val subExpInExp' =
adamc@133 75 U.Exp.mapB {typ = fn t => t,
adamc@133 76 exp = fn (xn, rep) => fn e =>
adamc@133 77 case e of
adamc@133 78 ERel xn' =>
adamc@133 79 (case Int.compare (xn', xn) of
adamc@133 80 EQUAL => #1 rep
adamc@133 81 | GREATER=> ERel (xn' - 1)
adamc@133 82 | LESS => e)
adamc@133 83 | _ => e,
adamc@133 84 bind = fn ((xn, rep), U.Exp.RelE _) => (xn+1, liftExpInExp 0 rep)
adamc@133 85 | (ctx, _) => ctx}
adamc@133 86
adamc@252 87 fun subExpInExp (n, e1) e2 =
adamc@252 88 let
adamc@252 89 val r = subExpInExp' (n, e1) e2
adamc@252 90 in
adamc@252 91 (*Print.prefaces "subExpInExp" [("e1", MonoPrint.p_exp MonoEnv.empty e1),
adamc@252 92 ("e2", MonoPrint.p_exp MonoEnv.empty e2),
adamc@252 93 ("r", MonoPrint.p_exp MonoEnv.empty r)];*)
adamc@252 94 r
adamc@252 95 end
adamc@133 96
adamc@133 97 fun typ c = c
adamc@133 98
adamc@316 99 val swapExpVars =
adamc@316 100 U.Exp.mapB {typ = fn t => t,
adamc@316 101 exp = fn lower => fn e =>
adamc@316 102 case e of
adamc@316 103 ERel xn =>
adamc@316 104 if xn = lower then
adamc@316 105 ERel (lower + 1)
adamc@316 106 else if xn = lower + 1 then
adamc@316 107 ERel lower
adamc@316 108 else
adamc@316 109 e
adamc@316 110 | _ => e,
adamc@316 111 bind = fn (lower, U.Exp.RelE _) => lower+1
adamc@316 112 | (lower, _) => lower}
adamc@316 113
adamc@341 114 val swapExpVarsPat =
adamc@341 115 U.Exp.mapB {typ = fn t => t,
adamc@341 116 exp = fn (lower, len) => fn e =>
adamc@341 117 case e of
adamc@341 118 ERel xn =>
adamc@341 119 if xn = lower then
adamc@341 120 ERel (lower + 1)
adamc@341 121 else if xn >= lower + 1 andalso xn < lower + 1 + len then
adamc@341 122 ERel (xn - 1)
adamc@341 123 else
adamc@341 124 e
adamc@341 125 | _ => e,
adamc@341 126 bind = fn ((lower, len), U.Exp.RelE _) => (lower+1, len)
adamc@341 127 | (st, _) => st}
adamc@341 128
adamc@258 129 datatype result = Yes of E.env | No | Maybe
adamc@258 130
adamc@183 131 fun match (env, p : pat, e : exp) =
adamc@183 132 case (#1 p, #1 e) of
adamc@258 133 (PWild, _) => Yes env
adamc@258 134 | (PVar (x, t), _) => Yes (E.pushERel env x t (SOME e))
adamc@183 135
adamc@280 136 | (PPrim (Prim.String s), EStrcat ((EPrim (Prim.String s'), _), _)) =>
adamc@280 137 if String.isPrefix s' s then
adamc@280 138 Maybe
adamc@280 139 else
adamc@280 140 No
adamc@280 141
adamc@183 142 | (PPrim p, EPrim p') =>
adamc@183 143 if Prim.equal (p, p') then
adamc@258 144 Yes env
adamc@183 145 else
adamc@258 146 No
adamc@183 147
adamc@188 148 | (PCon (_, PConVar n1, NONE), ECon (_, PConVar n2, NONE)) =>
adamc@183 149 if n1 = n2 then
adamc@258 150 Yes env
adamc@183 151 else
adamc@258 152 No
adamc@183 153
adamc@188 154 | (PCon (_, PConVar n1, SOME p), ECon (_, PConVar n2, SOME e)) =>
adamc@183 155 if n1 = n2 then
adamc@183 156 match (env, p, e)
adamc@183 157 else
adamc@258 158 No
adamc@183 159
adamc@188 160 | (PCon (_, PConFfi {mod = m1, con = con1, ...}, NONE), ECon (_, PConFfi {mod = m2, con = con2, ...}, NONE)) =>
adamc@185 161 if m1 = m2 andalso con1 = con2 then
adamc@258 162 Yes env
adamc@185 163 else
adamc@258 164 No
adamc@185 165
adamc@188 166 | (PCon (_, PConFfi {mod = m1, con = con1, ...}, SOME ep), ECon (_, PConFfi {mod = m2, con = con2, ...}, SOME e)) =>
adamc@185 167 if m1 = m2 andalso con1 = con2 then
adamc@185 168 match (env, p, e)
adamc@185 169 else
adamc@258 170 No
adamc@185 171
adamc@183 172 | (PRecord xps, ERecord xes) =>
adamc@183 173 let
adamc@183 174 fun consider (xps, env) =
adamc@183 175 case xps of
adamc@258 176 [] => Yes env
adamc@183 177 | (x, p, _) :: rest =>
adamc@183 178 case List.find (fn (x', _, _) => x' = x) xes of
adamc@258 179 NONE => No
adamc@183 180 | SOME (_, e, _) =>
adamc@183 181 case match (env, p, e) of
adamc@258 182 No => No
adamc@258 183 | Maybe => Maybe
adamc@258 184 | Yes env => consider (rest, env)
adamc@183 185 in
adamc@183 186 consider (xps, env)
adamc@183 187 end
adamc@183 188
adamc@258 189 | _ => Maybe
adamc@183 190
adamc@318 191 datatype event =
adamc@318 192 WritePage
adamc@318 193 | ReadDb
adamc@318 194 | WriteDb
adamc@318 195 | UseRel of int
adamc@318 196 | Unsure
adamc@318 197
adamc@318 198 fun p_event e =
adamc@318 199 let
adamc@318 200 open Print.PD
adamc@318 201 in
adamc@318 202 case e of
adamc@318 203 WritePage => string "WritePage"
adamc@318 204 | ReadDb => string "ReadDb"
adamc@318 205 | WriteDb => string "WriteDb"
adamc@318 206 | UseRel n => string ("UseRel" ^ Int.toString n)
adamc@318 207 | Unsure => string "Unsure"
adamc@318 208 end
adamc@318 209
adamc@318 210 fun patBinds (p, _) =
adamc@318 211 case p of
adamc@318 212 PWild => 0
adamc@318 213 | PVar _ => 1
adamc@318 214 | PPrim _ => 0
adamc@318 215 | PCon (_, _, NONE) => 0
adamc@318 216 | PCon (_, _, SOME p) => patBinds p
adamc@318 217 | PRecord xpts => foldl (fn ((_, p, _), n) => n + patBinds p) 0 xpts
adamc@318 218 | PNone _ => 0
adamc@318 219 | PSome (_, p) => patBinds p
adamc@318 220
adamc@318 221 fun summarize d (e, _) =
adamc@318 222 case e of
adamc@318 223 EPrim _ => []
adamc@318 224 | ERel n => if n >= d then [UseRel (n - d)] else []
adamc@318 225 | ENamed _ => []
adamc@318 226 | ECon (_, _, NONE) => []
adamc@318 227 | ECon (_, _, SOME e) => summarize d e
adamc@318 228 | ENone _ => []
adamc@318 229 | ESome (_, e) => summarize d e
adamc@318 230 | EFfi _ => []
adamc@318 231 | EFfiApp (_, _, es) => List.concat (map (summarize d) es)
adamc@319 232 | EApp ((EFfi _, _), e) => summarize d e
adamc@318 233 | EApp _ => [Unsure]
adamc@318 234 | EAbs _ => []
adamc@318 235
adamc@318 236 | ERecord xets => List.concat (map (summarize d o #2) xets)
adamc@318 237 | EField (e, _) => summarize d e
adamc@318 238
adamc@318 239 | ECase (e, pes, _) =>
adamc@318 240 let
adamc@318 241 val lss = map (fn (p, e) => summarize (d + patBinds p) e) pes
adamc@318 242 in
adamc@318 243 case lss of
adamc@318 244 [] => raise Fail "Empty pattern match"
adamc@318 245 | ls :: lss =>
adamc@318 246 if List.all (fn ls' => ls' = ls) lss then
adamc@318 247 summarize d e @ ls
adamc@318 248 else
adamc@318 249 [Unsure]
adamc@318 250 end
adamc@318 251 | EStrcat (e1, e2) => summarize d e1 @ summarize d e2
adamc@318 252
adamc@318 253 | EError (e, _) => summarize d e @ [Unsure]
adamc@318 254
adamc@318 255 | EWrite e => summarize d e @ [WritePage]
adamc@318 256
adamc@318 257 | ESeq (e1, e2) => summarize d e1 @ summarize d e2
adamc@318 258 | ELet (_, _, e1, e2) => summarize d e1 @ summarize (d + 1) e2
adamc@318 259
adamc@318 260 | EClosure (_, es) => List.concat (map (summarize d) es)
adamc@318 261
adamc@318 262 | EQuery {query, body, initial, ...} =>
adamc@318 263 List.concat [summarize d query,
adamc@319 264 summarize (d + 2) body,
adamc@318 265 summarize d initial,
adamc@318 266 [ReadDb]]
adamc@318 267
adamc@318 268 | EDml e => summarize d e @ [WriteDb]
adamc@338 269 | ENextval e => summarize d e @ [WriteDb]
adamc@318 270
adamc@133 271 fun exp env e =
adamc@133 272 case e of
adamc@183 273 ERel n =>
adamc@183 274 (case E.lookupERel env n of
adamc@183 275 (_, _, SOME e') => #1 e'
adamc@183 276 | _ => e)
adamc@183 277 | ENamed n =>
adamc@133 278 (case E.lookupENamed env n of
adamc@133 279 (_, _, SOME e', _) => #1 e'
adamc@133 280 | _ => e)
adamc@133 281
adamc@252 282 | EApp ((EAbs (x, t, _, e1), loc), e2) =>
adamc@252 283 ((*Print.prefaces "Considering" [("e1", MonoPrint.p_exp env e1),
adamc@252 284 ("e2", MonoPrint.p_exp env e2)];*)
adamc@252 285 if impure e2 then
adamc@252 286 #1 (reduceExp env (ELet (x, t, e2, e1), loc))
adamc@252 287 else
adamc@252 288 #1 (reduceExp env (subExpInExp (0, e2) e1)))
adamc@133 289
adamc@341 290 | ECase (e', pes, {disc, result}) =>
adamc@258 291 let
adamc@341 292 fun push () =
adamc@341 293 case result of
adamc@341 294 (TFun (dom, result), loc) =>
adamc@341 295 if List.all (fn (_, (EAbs _, _)) => true | _ => false) pes then
adamc@341 296 EAbs ("_", dom, result,
adamc@341 297 (ECase (liftExpInExp 0 e',
adamc@341 298 map (fn (p, (EAbs (_, _, _, e), _)) =>
adamc@341 299 (p, swapExpVarsPat (0, patBinds p) e)
adamc@341 300 | _ => raise Fail "MonoReduce ECase") pes,
adamc@341 301 {disc = disc, result = result}), loc))
adamc@341 302 else
adamc@341 303 e
adamc@341 304 | _ => e
adamc@341 305
adamc@258 306 fun search pes =
adamc@258 307 case pes of
adamc@341 308 [] => push ()
adamc@258 309 | (p, body) :: pes =>
adamc@341 310 case match (env, p, e') of
adamc@258 311 No => search pes
adamc@341 312 | Maybe => push ()
adamc@258 313 | Yes env => #1 (reduceExp env body)
adamc@258 314 in
adamc@258 315 search pes
adamc@258 316 end
adamc@183 317
adamc@252 318 | EField ((ERecord xes, _), x) =>
adamc@252 319 (case List.find (fn (x', _, _) => x' = x) xes of
adamc@252 320 SOME (_, e, _) => #1 e
adamc@252 321 | NONE => e)
adamc@252 322
adamc@252 323 | ELet (x1, t1, (ELet (x2, t2, e1, b1), loc), b2) =>
adamc@252 324 let
adamc@252 325 val e' = (ELet (x2, t2, e1,
adamc@252 326 (ELet (x1, t1, b1,
adamc@252 327 liftExpInExp 1 b2), loc)), loc)
adamc@252 328 in
adamc@253 329 (*Print.prefaces "ELet commute" [("e", MonoPrint.p_exp env (e, loc)),
adamc@253 330 ("e'", MonoPrint.p_exp env e')];*)
adamc@252 331 #1 (reduceExp env e')
adamc@252 332 end
adamc@252 333 | EApp ((ELet (x, t, e, b), loc), e') =>
adamc@252 334 #1 (reduceExp env (ELet (x, t, e,
adamc@252 335 (EApp (b, liftExpInExp 0 e'), loc)), loc))
adamc@316 336
adamc@316 337 | ELet (x, t, e, (EAbs (x', t' as (TRecord [], _), ran, e'), loc)) =>
adamc@316 338 EAbs (x', t', ran, (ELet (x, t, liftExpInExp 0 e, swapExpVars 0 e'), loc))
adamc@316 339
adamc@252 340 | ELet (x, t, e', b) =>
adamc@252 341 if impure e' then
adamc@318 342 let
adamc@318 343 val effs_e' = summarize 0 e'
adamc@318 344 val effs_b = summarize 0 b
adamc@318 345
adamc@318 346 fun does eff = List.exists (fn eff' => eff' = eff) effs_e'
adamc@318 347 val writesPage = does WritePage
adamc@318 348 val readsDb = does ReadDb
adamc@318 349 val writesDb = does WriteDb
adamc@318 350
adamc@318 351 fun verifyUnused eff =
adamc@318 352 case eff of
adamc@318 353 UseRel r => r <> 0
adamc@318 354 | Unsure => false
adamc@318 355 | _ => true
adamc@318 356
adamc@318 357 fun verifyCompatible effs =
adamc@318 358 case effs of
adamc@318 359 [] => false
adamc@318 360 | eff :: effs =>
adamc@318 361 case eff of
adamc@318 362 Unsure => false
adamc@318 363 | UseRel r =>
adamc@318 364 if r = 0 then
adamc@318 365 List.all verifyUnused effs
adamc@318 366 else
adamc@318 367 verifyCompatible effs
adamc@318 368 | WritePage => not writesPage andalso verifyCompatible effs
adamc@318 369 | ReadDb => not writesDb andalso verifyCompatible effs
adamc@318 370 | WriteDb => not writesDb andalso not readsDb andalso verifyCompatible effs
adamc@318 371 in
adamc@318 372 (*Print.prefaces "verifyCompatible"
adamc@318 373 [("e'", MonoPrint.p_exp env e'),
adamc@318 374 ("b", MonoPrint.p_exp (E.pushERel env x t NONE) b),
adamc@318 375 ("effs_e'", Print.p_list p_event effs_e'),
adamc@318 376 ("effs_b", Print.p_list p_event effs_b)];*)
adamc@318 377 if verifyCompatible effs_b then
adamc@318 378 #1 (reduceExp env (subExpInExp (0, e') b))
adamc@318 379 else
adamc@318 380 e
adamc@318 381 end
adamc@252 382 else
adamc@252 383 #1 (reduceExp env (subExpInExp (0, e') b))
adamc@252 384
adamc@268 385 | EStrcat ((EPrim (Prim.String s1), _), (EPrim (Prim.String s2), _)) =>
adamc@268 386 EPrim (Prim.String (s1 ^ s2))
adamc@268 387
adamc@133 388 | _ => e
adamc@133 389
adamc@252 390 and bind (env, b) =
adamc@252 391 case b of
adamc@252 392 U.Decl.Datatype (x, n, xncs) => E.pushDatatype env x n xncs
adamc@252 393 | U.Decl.RelE (x, t) => E.pushERel env x t NONE
adamc@252 394 | U.Decl.NamedE (x, n, t, eo, s) => E.pushENamed env x n t (Option.map (reduceExp env) eo) s
adamc@252 395
adamc@133 396 and reduceExp env = U.Exp.mapB {typ = typ, exp = exp, bind = bind} env
adamc@133 397
adamc@133 398 fun decl env d = d
adamc@133 399
adamc@133 400 val reduce = U.File.mapB {typ = typ, exp = exp, decl = decl, bind = bind} E.empty
adamc@133 401
adamc@133 402 end