CPSOptimizer.scala 14.7 KB
Newer Older
Sapphie's avatar
Sapphie committed
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
package l3

import scala.collection.mutable.{ Map => MutableMap }

abstract class CPSOptimizer[T <: CPSTreeModule { type Name = Symbol }]
  (val treeModule: T) {
  import treeModule._

  protected def rewrite(tree: Tree): Tree = {
    val simplifiedTree = fixedPoint(tree)(shrink)
    val maxSize = size(simplifiedTree) * 3 / 2
    fixedPoint(simplifiedTree, 8) { t => inline(t, maxSize) }
  }

  private case class Count(applied: Int = 0, asValue: Int = 0)

  private case class State(
    census: Map[Name, Count],
    aSubst: Subst[Atom] = emptySubst,
    cSubst: Subst[Name] = emptySubst,
    eInvEnv: Map[(ValuePrimitive, Seq[Atom]), Atom] = Map.empty,
    cEnv: Map[Name, Cnt] = Map.empty,
    fEnv: Map[Name, Fun] = Map.empty) {

    def dead(s: Name): Boolean =
      ! census.contains(s)
    def appliedOnce(s: Name): Boolean =
      census.get(s).contains(Count(applied = 1, asValue = 0))

    def withASubst(from: Atom, to: Atom): State =
      copy(aSubst = aSubst + (from -> aSubst(to)))
    def withASubst(from: Name, to: Atom): State =
      withASubst(AtomN(from), to)
    def withASubst(from: Name, to: Literal): State =
      withASubst(from, AtomL(to))
    def withASubst(from: Seq[Name], to: Seq[Atom]): State =
      copy(aSubst = aSubst ++ (from.map(AtomN) zip to.map(aSubst)))

    def withCSubst(from: Name, to: Name): State =
      copy(cSubst = cSubst + (from -> cSubst(to)))

    def withExp(atom: Atom, prim: ValuePrimitive, args: Seq[Atom]): State =
      copy(eInvEnv = eInvEnv + ((prim, args) -> atom))
    def withExp(name: Name, prim: ValuePrimitive, args: Seq[Atom]): State =
      withExp(AtomN(name), prim, args)

    def withCnts(cnts: Seq[Cnt]): State =
      copy(cEnv = cEnv ++ (cnts.map(_.name) zip cnts))
    def withFuns(funs: Seq[Fun]): State =
      copy(fEnv = fEnv ++ (funs.map(_.name) zip funs))
  }

  // Shrinking optimizations

  private def shrink(tree: Tree): Tree =
    shrink(tree, State(census(tree)))

58
  private def shrink(tree: Tree, s: State): Tree = tree match {
Sapphie's avatar
Sapphie committed
59
60
61
62
63
64
65
66
67
68
69
70
71
    
    case AppF(funAtom, retC, args) =>
      funAtom match {
        case AtomN(n) if s.fEnv.contains(n) && s.appliedOnce(n) =>
          // Inline
          val fun = s.fEnv(n)
          val newState = s.withASubst(fun.args, args)
                          .withCSubst(fun.retC, retC)
          val newBody = shrink(fun.body, newState)
          newBody
        case _ => tree
      }

72
73
74
75
    case LetF(funs, body) =>
      val undeadFuns = funs.filter(fun => !s.dead(fun.name))
      val undeadShrunkFuns = undeadFuns.map { fun =>
        Fun(fun.name, fun.retC, fun.args, shrink(fun.body, s))}
Sapphie's avatar
Sapphie committed
76
77
      val nonInlined = undeadShrunkFuns
        .filter(fun => !s.appliedOnce(fun.name))
78
79
80

      val newState = s.withFuns(undeadShrunkFuns)
      val newBody = shrink(body, newState)
Sapphie's avatar
Sapphie committed
81
      if (nonInlined.isEmpty) {
82
83
        newBody
      } else {
Sapphie's avatar
Sapphie committed
84
        LetF(nonInlined, newBody)
85
86
      }
    
Sapphie's avatar
Sapphie committed
87
88
89
90
91
92
93
94
95
    case LetP(name, prim, args, body) =>
      if (s.dead(name) && !impure(prim)) {
        shrink(body, s)
      } else {
        val replacedArgs = args map { a => s.aSubst.getOrElse(a, a)}
        val primArgPair = (prim, replacedArgs)
        if (!unstable(prim) && s.eInvEnv.contains(primArgPair)) {
          val newS = s.withASubst(name, s.eInvEnv(primArgPair))
          val newBody = shrink(body, newS)
Sapphie's avatar
Sapphie committed
96
          newBody
Sapphie's avatar
Sapphie committed
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
        } else {
          val newS = s.withExp(name, prim, replacedArgs)
          LetP(name, prim, replacedArgs, shrink(body, newS))
        }
      }

    case LetC(cnts, body) =>
      val undeadConts = cnts.filter(cnt => !s.dead(cnt.name))
      val undeadShrunkConts = undeadConts.map { cnt =>
        val newBody = shrink(cnt.body, s)
        Cnt(cnt.name, cnt.args, newBody)
      }

      val nonInlinedConts = undeadShrunkConts.filter { cnt =>
        !s.appliedOnce(cnt.name)
      }

      val newBody = shrink(body, s.withCnts(undeadShrunkConts))
Sapphie's avatar
Sapphie committed
115
      if (nonInlinedConts.isEmpty) {
Sapphie's avatar
Sapphie committed
116
117
        newBody
      } else {
Sapphie's avatar
Sapphie committed
118
        LetC(nonInlinedConts, newBody)
119
120
      }

Sapphie's avatar
Sapphie committed
121
122
123
    case Halt(a) =>
      Halt(s.aSubst.getOrElse(a, a))

124
  }
Sapphie's avatar
Sapphie committed
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
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273

  // (Non-shrinking) inlining

  private def inline(tree: Tree, maxSize: Int): Tree = {
    def copyT(tree: Tree, subV: Subst[Atom], subC: Subst[Name]): Tree = {
      (tree: @unchecked) match {
        case LetP(name, prim, args, body) =>
          val name1 = name.copy()
          LetP(name1, prim, args map subV,
               copyT(body, subV + (AtomN(name) -> AtomN(name1)), subC))
        case LetC(cnts, body) =>
          val names = cnts map (_.name)
          val names1 = names map (_.copy())
          val subC1 = subC ++ (names zip names1)
          LetC(cnts map (copyC(_, subV, subC1)), copyT(body, subV, subC1))
        case LetF(funs, body) =>
          val names = funs map (_.name)
          val names1 = names map (_.copy())
          val subV1 = subV ++ ((names map AtomN) zip (names1 map AtomN))
          LetF(funs map (copyF(_, subV1, subC)), copyT(body, subV1, subC))
        case AppC(cnt, args) =>
          AppC(subC(cnt), args map subV)
        case AppF(fun, retC, args) =>
          AppF(subV(fun), subC(retC), args map subV)
        case If(cond, args, thenC, elseC) =>
          If(cond, args map subV, subC(thenC), subC(elseC))
        case Halt(arg) =>
          Halt(subV(arg))
      }
    }

    def copyC(cnt: Cnt, subV: Subst[Atom], subC: Subst[Name]): Cnt = {
      val args1 = cnt.args map (_.copy())
      val subV1 = subV ++ ((cnt.args map AtomN) zip (args1 map AtomN))
      Cnt(subC(cnt.name), args1, copyT(cnt.body, subV1, subC))
    }

    def copyF(fun: Fun, subV: Subst[Atom], subC: Subst[Name]): Fun = {
      val retC1 = fun.retC.copy()
      val subC1 = subC + (fun.retC -> retC1)
      val args1 = fun.args map (_.copy())
      val subV1 = subV ++ ((fun.args map AtomN) zip (args1 map AtomN))
      val AtomN(funName1) = subV(AtomN(fun.name))
      Fun(funName1, retC1, args1, copyT(fun.body, subV1, subC1))
    }

    val fibonacci = Seq(1, 2, 3, 5, 8, 13)

    val trees = LazyList.iterate((0, tree), fibonacci.length){ case (i, tree) =>
      val funLimit = fibonacci(i)
      val cntLimit = i

      def sameLen[T,U](formalArgs: Seq[T], actualArgs: Seq[U]): Boolean =
        formalArgs.length == actualArgs.length

      def inlineT(tree: Tree)(implicit s: State): Tree = ???

      (i + 1, fixedPoint(inlineT(tree)(State(census(tree))))(shrink))
    }

    trees.takeWhile{ case (_, tree) => size(tree) <= maxSize }.last._2
  }

  // Census computation
  private def census(tree: Tree): Map[Name, Count] = {
    val census = MutableMap[Name, Count]().withDefault(_ => Count())
    val rhs = MutableMap[Name, Tree]()

    def incAppUseN(name: Name): Unit = {
      val currCount = census(name)
      census(name) = currCount.copy(applied = currCount.applied + 1)
      rhs.remove(name).foreach(addToCensus)
    }

    def incAppUseA(atom: Atom): Unit =
      atom.asName.foreach(incAppUseN(_))

    def incValUseN(name: Name): Unit = {
      val currCount = census(name)
      census(name) = currCount.copy(asValue = currCount.asValue + 1)
      rhs.remove(name).foreach(addToCensus)
    }

    def incValUseA(atom: Atom): Unit =
      atom.asName.foreach(incValUseN(_))

    def addToCensus(tree: Tree): Unit = (tree: @unchecked) match {
      case LetP(_, _, args, body) =>
        args foreach incValUseA; addToCensus(body)
      case LetC(cnts, body) =>
        rhs ++= (cnts map { c => (c.name, c.body) }); addToCensus(body)
      case LetF(funs, body) =>
        rhs ++= (funs map { f => (f.name, f.body) }); addToCensus(body)
      case AppC(cnt, args) =>
        incAppUseN(cnt); args foreach incValUseA
      case AppF(fun, retC, args) =>
        incAppUseA(fun); incValUseN(retC); args foreach incValUseA
      case If(_, args, thenC, elseC) =>
        args foreach incValUseA; incValUseN(thenC); incValUseN(elseC)
      case Halt(arg) =>
        incValUseA(arg)
    }

    addToCensus(tree)
    census.toMap
  }

  private def size(tree: Tree): Int = (tree: @unchecked) match {
    case LetP(_, _, _, body) => size(body) + 1
    case LetC(cs, body) => (cs map { c => size(c.body) }).sum + size(body)
    case LetF(fs, body) => (fs map { f => size(f.body) }).sum + size(body)
    case AppC(_, _) | AppF(_, _, _) | If(_, _, _, _) | Halt(_) => 1
  }

  protected val impure: ValuePrimitive => Boolean
  protected val unstable: ValuePrimitive => Boolean

  protected val blockAllocTag: PartialFunction[ValuePrimitive, Literal]
  protected val blockTag: ValuePrimitive
  protected val blockLength: ValuePrimitive

  protected val identity: ValuePrimitive

  protected val leftNeutral: Set[(Literal, ValuePrimitive)]
  protected val rightNeutral: Set[(ValuePrimitive, Literal)]
  protected val leftAbsorbing: Set[(Literal, ValuePrimitive)]
  protected val rightAbsorbing: Set[(ValuePrimitive, Literal)]

  protected val sameArgReduce: PartialFunction[(ValuePrimitive, Atom), Atom]
  protected val sameArgReduceC: TestPrimitive => Boolean

  protected val vEvaluator: PartialFunction[(ValuePrimitive, Seq[Literal]),
                                            Literal]
  protected val cEvaluator: PartialFunction[(TestPrimitive, Seq[Literal]),
                                            Boolean]
}

object CPSOptimizerHigh extends CPSOptimizer(SymbolicCPSTreeModule)
    with (SymbolicCPSTreeModule.Tree => SymbolicCPSTreeModule.Tree) {
  import treeModule._
  import L3Primitive._

  def apply(tree: Tree): Tree =
    rewrite(tree)

  import scala.language.implicitConversions
  private[this] implicit def l3IntToLit(i: L3Int): Literal = IntLit(i)
  private[this] implicit def intToLit(i: Int): Literal = IntLit(L3Int(i))

Sapphie's avatar
Sapphie committed
274
275
  protected val impure: ValuePrimitive => Boolean =
    Set(ByteRead, ByteWrite, BlockSet)
Sapphie's avatar
Sapphie committed
276
277
278

  protected val unstable: ValuePrimitive => Boolean = ???

Sapphie's avatar
Sapphie committed
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
  protected val blockAllocTag: PartialFunction[ValuePrimitive, Literal] = {
    case BlockAlloc(t) => t
  }
  protected val blockTag: ValuePrimitive = BlockTag
  protected val blockLength: ValuePrimitive = BlockLength

  protected val identity: ValuePrimitive = Id

  protected val leftNeutral: Set[(Literal, ValuePrimitive)] = Set(
    (IntLit(L3Int(0)), IntAdd),
    (IntLit(L3Int(1)), IntMul),
    (IntLit(L3Int((-1 << 1) >> 1)), IntBitwiseAnd),
    (IntLit(L3Int(0)), IntBitwiseOr),
    (IntLit(L3Int(0)), IntBitwiseXOr)
  )
  protected val rightNeutral: Set[(ValuePrimitive, Literal)] = Set(
    (IntAdd, IntLit(L3Int(0))),
    (IntSub, IntLit(L3Int(0))),
    (IntMul, IntLit(L3Int(1))),
    (IntDiv, IntLit(L3Int(1))),
    (IntShiftLeft, IntLit(L3Int(0))),
    (IntShiftRight, IntLit(L3Int(0))),
    (IntBitwiseAnd, IntLit(L3Int((-1 << 1) >> 1))),
    (IntBitwiseOr, IntLit(L3Int(0))),
    (IntBitwiseXOr, IntLit(L3Int(0))),
  )

  protected val leftAbsorbing: Set[(Literal, ValuePrimitive)] = Set(
    (IntLit(L3Int(0)), IntMul),
    (IntLit(L3Int(0)), IntMod),
    (IntLit(L3Int(0)), IntBitwiseAnd),
    (IntLit(L3Int((-1 << 1) >> 1)), IntBitwiseOr),
    (IntLit(L3Int(0)), IntShiftLeft),
    (IntLit(L3Int(0)), IntShiftRight)
  )

  protected val rightAbsorbing: Set[(ValuePrimitive, Literal)] = Set(
    (IntMul, IntLit(L3Int(0))),
    (IntBitwiseAnd, IntLit(L3Int(0))),
    (IntBitwiseOr, IntLit(L3Int((-1 << 1) >> 1)))
  )

  protected val sameArgReduce: PartialFunction[(ValuePrimitive, Atom), Atom] = {
    case (IntBitwiseAnd | IntBitwiseOr, a) => a
    case (IntSub | IntBitwiseXOr | IntMod, _) => AtomL(IntLit(L3Int(0)))
    case (IntDiv, _) => AtomL(IntLit(L3Int(1)))
  }
Sapphie's avatar
Sapphie committed
326
327


Sapphie's avatar
Sapphie committed
328
329
330
331
  protected val sameArgReduceC: PartialFunction[TestPrimitive, Boolean] = {
    case IntLt => false
    case IntLe | Eq => true
  }
Sapphie's avatar
Sapphie committed
332
333

  protected val vEvaluator: PartialFunction[(ValuePrimitive, Seq[Literal]),
Sapphie's avatar
Sapphie committed
334
335
336
337
338
339
340
341
342
343
344
345
346
347
                                            Literal] = {
    case (vPrim, Seq(IntLit(x), IntLit(y))) => vPrim match {
      case IntAdd => IntLit(x + y)
      case IntSub => IntLit(x - y)
      case IntMod => IntLit(x % y)
      case IntDiv => IntLit(x / y)
      case IntMul => IntLit(x * y)
      case IntBitwiseAnd => IntLit(x & y)
      case IntBitwiseOr => IntLit(x | y)
      case IntBitwiseXOr => IntLit(x ^ y)
      case IntShiftLeft => IntLit(x << y)
      case IntShiftRight => IntLit(x >> y)
    }
  }
Sapphie's avatar
Sapphie committed
348
349

  protected val cEvaluator: PartialFunction[(TestPrimitive, Seq[Literal]),
Sapphie's avatar
Sapphie committed
350
351
352
353
354
                                            Boolean] = {
    case (IntLe, Seq(IntLit(x), IntLit(y))) => x <= y
    case (IntLt, Seq(IntLit(x), IntLit(y))) => x < y
    case (Eq, Seq(l1, l2)) => l1 == l2
  }
Sapphie's avatar
Sapphie committed
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
}

object CPSOptimizerLow extends CPSOptimizer(SymbolicCPSTreeModuleLow)
    with (SymbolicCPSTreeModuleLow.LetF => SymbolicCPSTreeModuleLow.LetF) {
  import treeModule._
  import CPSValuePrimitive._
  import CPSTestPrimitive._

  def apply(tree: LetF): LetF = rewrite(tree) match {
    case tree @ LetF(_, _) => tree
    case other => LetF(Seq(), other)
  }

  protected val impure: ValuePrimitive => Boolean =
    Set(BlockSet, ByteRead, ByteWrite)

  protected val unstable: ValuePrimitive => Boolean = {
    case BlockAlloc(_) | BlockGet | ByteRead => true
    case _ => false
  }

  protected val blockAllocTag: PartialFunction[ValuePrimitive, Literal] = {
    case BlockAlloc(tag) => tag
  }
  protected val blockTag: ValuePrimitive = BlockTag
  protected val blockLength: ValuePrimitive = BlockLength

  protected val identity: ValuePrimitive = Id

  protected val leftNeutral: Set[(Literal, ValuePrimitive)] =
    Set((0, Add), (1, Mul), (~0, And), (0, Or), (0, XOr))
  protected val rightNeutral: Set[(ValuePrimitive, Literal)] =
    Set((Add, 0), (Sub, 0), (Mul, 1), (Div, 1),
        (ShiftLeft, 0), (ShiftRight, 0),
        (And, ~0), (Or, 0), (XOr, 0))

  protected val leftAbsorbing: Set[(Literal, ValuePrimitive)] =
    Set((0, Mul), (0, Div),
        (0, ShiftLeft), (0, ShiftRight),
        (0, And), (~0, Or))
  protected val rightAbsorbing: Set[(ValuePrimitive, Literal)] =
    Set((Mul, 0), (And, 0), (Or, ~0))

  protected val sameArgReduce: PartialFunction[(ValuePrimitive, Atom), Atom] = {
    case (And | Or, a) => a
    case (Sub | Mod | XOr, _) => AtomL(0)
    case (Div, _) => AtomL(1)
  }

  protected val sameArgReduceC: PartialFunction[TestPrimitive, Boolean] = {
    case Le | Eq => true
    case Lt => false
  }

  protected val vEvaluator: PartialFunction[(ValuePrimitive, Seq[Literal]),
                                            Literal] = {
    case (Add, Seq(x, y)) => x + y
    case (Sub, Seq(x, y)) => x - y
    case (Mul, Seq(x, y)) => x * y
    case (Div, Seq(x, y)) if y.toInt != 0 => x / y
    case (Mod, Seq(x, y)) if y.toInt != 0 => x % y

    case (ShiftLeft,  Seq(x, y)) => x << y
    case (ShiftRight, Seq(x, y)) => x >> y
    case (And, Seq(x, y)) => x & y
    case (Or,  Seq(x, y)) => x | y
    case (XOr, Seq(x, y)) => x ^ y
  }

  protected val cEvaluator: PartialFunction[(TestPrimitive, Seq[Literal]),
                                            Boolean] = {
    case (Lt, Seq(x, y)) => x < y
    case (Le, Seq(x, y)) => x <= y
    case (Eq, Seq(x, y)) => x == y
  }
}