Revert "Move dart2js from sdk/lib/_internal/compiler to pkg/compiler"

pkg/compiler/lib/src/cps_ir/shrinking_reductions.dart

Index: pkg/compiler/lib/src/cps_ir/shrinking_reductions.dart
diff --git a/pkg/compiler/lib/src/cps_ir/shrinking_reductions.dart b/pkg/compiler/lib/src/cps_ir/shrinking_reductions.dart
deleted file mode 100644
index f14ece5a98f9ee8b123bee06c896fb666b410602..0000000000000000000000000000000000000000
--- a/pkg/compiler/lib/src/cps_ir/shrinking_reductions.dart
+++ /dev/null
@@ -1,439 +0,0 @@
-// Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-part of dart2js.optimizers;
-
-/**
- * [[ShrinkingReducer]] applies shrinking reductions to CPS terms as described
- * in 'Compiling with Continuations, Continued' by Andrew Kennedy.
- */
-class ShrinkingReducer implements Pass {
-  _RedexVisitor _redexVisitor;
-  Set<_ReductionTask> _worklist;
-
-  static final _DeletedNode _DELETED = new _DeletedNode();
-
-  /// Applies shrinking reductions to root, mutating root in the process.
-  void rewrite(FunctionDefinition root) {
-    if (root.isAbstract) return;
-
-    _worklist = new Set<_ReductionTask>();
-    _redexVisitor = new _RedexVisitor(_worklist);
-
-    // Set all parent pointers.
-    new _ParentVisitor().visit(root);
-
-    // Sweep over the term, collecting redexes into the worklist.
-    _redexVisitor.visitFunctionDefinition(root);
-
-    // Process the worklist.
-    while (_worklist.isNotEmpty) {
-      _ReductionTask task = _worklist.first;
-      _worklist.remove(task);
-      _processTask(task);
-    }
-  }
-
-  /// Removes the given node from the CPS graph, replacing it with its body
-  /// and marking it as deleted. The node's parent must be a [[InteriorNode]].
-  void _removeNode(InteriorNode node) {
-    Node body           = node.body;
-    InteriorNode parent = node.parent;
-    assert(parent.body == node);
-
-    body.parent = parent;
-    parent.body = body;
-    node.parent = _DELETED;
-  }
-
-  void _processTask(_ReductionTask task) {
-    // Lazily skip tasks for deleted nodes.
-    if (task.node.parent == _DELETED) {
-      return;
-    }
-
-    switch (task.kind) {
-      case _ReductionKind.DEAD_VAL:
-        _reduceDeadVal(task);
-        break;
-      case _ReductionKind.DEAD_CONT:
-        _reduceDeadCont(task);
-        break;
-      case _ReductionKind.BETA_CONT_LIN:
-        _reduceBetaContLin(task);
-        break;
-      case _ReductionKind.ETA_CONT:
-        _reduceEtaCont(task);
-        break;
-      default:
-        assert(false);
-    }
-  }
-
-  /// Applies the dead-val reduction:
-  ///   letprim x = V in E -> E (x not free in E).
-  void _reduceDeadVal(_ReductionTask task) {
-    assert(_isDeadVal(task.node));
-
-    // Remove dead primitive.
-    LetPrim letPrim = task.node;;
-    _removeNode(letPrim);
-
-    // Perform bookkeeping on removed body and scan for new redexes.
-    new _RemovalRedexVisitor(_worklist).visit(letPrim.primitive);
-  }
-
-  /// Applies the dead-cont reduction:
-  ///   letcont k x = E0 in E1 -> E1 (k not free in E1).
-  void _reduceDeadCont(_ReductionTask task) {
-    assert(_isDeadCont(task.node));
-
-    // Remove dead continuation.
-    LetCont letCont = task.node;
-    _removeNode(letCont);
-
-    // Perform bookkeeping on removed body and scan for new redexes.
-    new _RemovalRedexVisitor(_worklist).visit(letCont.continuation);
-  }
-
-  /// Applies the beta-cont-lin reduction:
-  ///   letcont k x = E0 in E1[k y] -> E1[E0[y/x]] (k not free in E1).
-  void _reduceBetaContLin(_ReductionTask task) {
-    // Might have been mutated, recheck if reduction is still valid.
-    // In the following example, the beta-cont-lin reduction of k0 could have
-    // been invalidated by removal of the dead continuation k1:
-    //
-    //  letcont k0 x0 = E0 in
-    //    letcont k1 x1 = k0 x1 in
-    //      return x2
-    if (!_isBetaContLin(task.node)) {
-      return;
-    }
-
-    // Remove the continuation.
-    LetCont letCont = task.node;
-    Continuation cont = letCont.continuation;
-    _removeNode(letCont);
-
-    // Replace its invocation with the continuation body.
-    InvokeContinuation invoke = cont.firstRef.parent;
-    InteriorNode invokeParent = invoke.parent;
-
-    cont.body.parent = invokeParent;
-    invokeParent.body = cont.body;
-
-    // Substitute the invocation argument for the continuation parameter.
-    for (int i = 0; i < invoke.arguments.length; i++) {
-      Reference argRef = invoke.arguments[i];
-      argRef.definition.substituteFor(cont.parameters[i]);
-    }
-
-    // Perform bookkeeping on removed body and scan for new redexes.
-    new _RemovalRedexVisitor(_worklist).visit(invoke);
-  }
-
-  /// Applies the eta-cont reduction:
-  ///   letcont k x = j x in E -> E[j/k].
-  /// If k is unused, degenerates to dead-cont.
-  void _reduceEtaCont(_ReductionTask task) {
-    // Might have been mutated, recheck if reduction is still valid.
-    // In the following example, the eta-cont reduction of k1 could have been
-    // invalidated by an earlier beta-cont-lin reduction of k0.
-    //
-    //  letcont k0 x0 = E0 in
-    //    letcont k1 x1 = k0 x1 in E1
-    if (!_isEtaCont(task.node)) {
-      return;
-    }
-
-    // Remove the continuation.
-    LetCont letCont   = task.node;
-    Continuation cont = letCont.continuation;
-    _removeNode(letCont);
-
-    InvokeContinuation invoke = cont.body;
-    Continuation wrappedCont = invoke.continuation.definition;
-
-    // Replace all occurrences with the wrapped continuation.
-    wrappedCont.substituteFor(cont);
-
-    // Perform bookkeeping on removed body and scan for new redexes.
-    new _RemovalRedexVisitor(_worklist).visit(cont);
-  }
-}
-
-/// Returns true iff the bound primitive is unused.
-bool _isDeadVal(LetPrim node) => !node.primitive.hasAtLeastOneUse;
-
-/// Returns true iff the bound continuation is unused.
-bool _isDeadCont(LetCont node) => !node.continuation.hasAtLeastOneUse;
-
-/// Returns true iff the bound continuation is used exactly once, and that
-/// use is as the receiver of a continuation invocation.
-bool _isBetaContLin(LetCont node) {
-  Continuation cont = node.continuation;
-  if (!cont.hasExactlyOneUse) {
-    return false;
-  }
-
-  if (cont.firstRef.parent is InvokeContinuation) {
-    InvokeContinuation invoke = cont.firstRef.parent;
-    return (cont == invoke.continuation.definition);
-  }
-
-  return false;
-
-}
-
-/// Returns true iff the bound continuation consists of a continuation
-/// invocation, passing on all parameters. Special cases exist (see below).
-bool _isEtaCont(LetCont node) {
-  Continuation cont = node.continuation;
-  if (!(cont.body is InvokeContinuation)) {
-    return false;
-  }
-
-  InvokeContinuation invoke = cont.body;
-  Continuation invokedCont = invoke.continuation.definition;
-
-  // Do not eta-reduce return join-points since the resulting code is worse
-  // in the common case (i.e. returns are moved inside `if` branches).
-  if (invokedCont.isReturnContinuation) {
-    return false;
-  }
-
-  // Translation to direct style generates different statements for recursive
-  // and non-recursive invokes. It should be possible to apply eta-cont, but
-  // higher order continuations require escape analysis, left as a possibility
-  // for future improvements.
-  if (invoke.isRecursive) {
-    return false;
-  }
-
-  if (cont.parameters.length != invoke.arguments.length) {
-    return false;
-  }
-
-  // TODO(jgruber): Linear in the parameter count. Can be improved to near
-  // constant time by using union-find data structure.
-  for (int i = 0; i < cont.parameters.length; i++) {
-    if (invoke.arguments[i].definition != cont.parameters[i]) {
-      return false;
-    }
-  }
-
-  return true;
-}
-
-/// Traverses a term and adds any found redexes to the worklist.
-class _RedexVisitor extends RecursiveVisitor {
-  final Set<_ReductionTask> worklist;
-
-  _RedexVisitor(this.worklist);
-
-  void processLetPrim(LetPrim node) {
-    if (node.parent == ShrinkingReducer._DELETED) {
-      return;
-    } else if (_isDeadVal(node)) {
-      worklist.add(new _ReductionTask(_ReductionKind.DEAD_VAL, node));
-    }
-  }
-
-  void processLetCont(LetCont node) {
-    if (node.parent == ShrinkingReducer._DELETED) {
-      return;
-    } else if (_isDeadCont(node)) {
-      worklist.add(new _ReductionTask(_ReductionKind.DEAD_CONT, node));
-    } else if (_isEtaCont(node)) {
-      worklist.add(new _ReductionTask(_ReductionKind.ETA_CONT, node));
-    } else if (_isBetaContLin(node)){
-      worklist.add(new _ReductionTask(_ReductionKind.BETA_CONT_LIN, node));
-    }
-  }
-}
-
-/// Traverses a deleted CPS term, marking existing tasks associated with a node
-/// within the term as deleted (which causes them to be skipped lazily when
-/// popped from the worklist), and adding newly created redexes to the worklist.
-class _RemovalRedexVisitor extends _RedexVisitor {
-  _RemovalRedexVisitor(Set<_ReductionTask> worklist) : super(worklist);
-
-  void processLetPrim(LetPrim node) {
-    node.parent = ShrinkingReducer._DELETED;
-  }
-
-  void processLetCont(LetCont node) {
-    node.parent = ShrinkingReducer._DELETED;
-  }
-
-  void processReference(Reference reference) {
-    reference.unlink();
-
-    if (reference.definition is Primitive) {
-      Primitive primitive = reference.definition;
-      Node parent = primitive.parent;
-      if (parent is LetPrim && _isDeadVal(parent)) {
-        worklist.add(new _ReductionTask(_ReductionKind.DEAD_VAL, parent));
-      }
-    } else if (reference.definition is Continuation) {
-      Continuation cont = reference.definition;
-      if (cont.isRecursive && cont.hasAtMostOneUse) {
-        // Convert recursive to nonrecursive continuations.
-        // If the continuation is still in use, it is either dead and will be
-        // removed, or it is called nonrecursively outside its body.
-        cont.isRecursive = false;
-      }
-      Node parent = cont.parent;
-      if (parent is LetCont && _isDeadCont(parent)) {
-        worklist.add(new _ReductionTask(_ReductionKind.DEAD_CONT, parent));
-      }
-    }
-  }
-}
-
-/// Traverses the CPS term and sets node.parent for each visited node.
-class _ParentVisitor extends RecursiveVisitor {
-
-  processFunctionDefinition(FunctionDefinition node) {
-    node.body.parent = node;
-    node.parameters.forEach((Parameter p) => p.parent = node);
-  }
-
-  // Expressions.
-
-  processLetPrim(LetPrim node) {
-    node.primitive.parent = node;
-    node.body.parent = node;
-  }
-
-  processLetCont(LetCont node) {
-    node.continuation.parent = node;
-    node.body.parent = node;
-  }
-
-  processInvokeStatic(InvokeStatic node) {
-    node.continuation.parent = node;
-    node.arguments.forEach((Reference ref) => ref.parent = node);
-  }
-
-  processInvokeContinuation(InvokeContinuation node) {
-    node.continuation.parent = node;
-    node.arguments.forEach((Reference ref) => ref.parent = node);
-  }
-
-  processInvokeMethod(InvokeMethod node) {
-    node.receiver.parent = node;
-    node.continuation.parent = node;
-    node.arguments.forEach((Reference ref) => ref.parent = node);
-  }
-
-  processInvokeSuperMethod(InvokeSuperMethod node) {
-    node.continuation.parent = node;
-    node.arguments.forEach((Reference ref) => ref.parent = node);
-  }
-
-  processInvokeConstructor(InvokeConstructor node) {
-    node.continuation.parent = node;
-    node.arguments.forEach((Reference ref) => ref.parent = node);
-  }
-
-  processConcatenateStrings(ConcatenateStrings node) {
-    node.continuation.parent = node;
-    node.arguments.forEach((Reference ref) => ref.parent = node);
-  }
-
-  processBranch(Branch node) {
-    node.condition.parent = node;
-    node.trueContinuation.parent = node;
-    node.falseContinuation.parent = node;
-  }
-
-  processTypeOperator(TypeOperator node) {
-    node.continuation.parent = node;
-    node.receiver.parent = node;
-  }
-
-  processSetClosureVariable(SetClosureVariable node) {
-    node.body.parent = node;
-    node.value.parent = node;
-  }
-
-  processDeclareFunction(DeclareFunction node) {
-    node.definition.parent = node;
-    node.body.parent = node;
-  }
-
-  // Definitions.
-
-  processLiteralList(LiteralList node) {
-    node.values.forEach((Reference ref) => ref.parent = node);
-  }
-
-  processLiteralMap(LiteralMap node) {
-    node.entries.forEach((LiteralMapEntry entry) {
-      entry.key.parent = node;
-      entry.value.parent = node;
-    });
-  }
-
-  processCreateFunction(CreateFunction node) {
-    node.definition.parent = node;
-  }
-
-  processContinuation(Continuation node) {
-    node.body.parent = node;
-    node.parameters.forEach((Parameter param) => param.parent = node);
-  }
-
-  // Conditions.
-
-  processIsTrue(IsTrue node) {
-    node.value.parent = node;
-  }
-}
-
-class _ReductionKind {
-  final String name;
-  final int hashCode;
-
-  const _ReductionKind(this.name, this.hashCode);
-
-  static const _ReductionKind DEAD_VAL = const _ReductionKind('dead-val', 0);
-  static const _ReductionKind DEAD_CONT = const _ReductionKind('dead-cont', 1);
-  static const _ReductionKind BETA_CONT_LIN =
-      const _ReductionKind('beta-cont-lin', 2);
-  static const _ReductionKind ETA_CONT = const _ReductionKind('eta-cont', 3);
-
-  String toString() => name;
-}
-
-/// Represents a reduction task on the worklist. Implements both hashCode and
-/// operator== since instantiations are used as Set elements.
-class _ReductionTask {
-  final _ReductionKind kind;
-  final Node node;
-
-  int get hashCode {
-    assert(kind.hashCode < (1 << 2));
-    return (node.hashCode << 2) | kind.hashCode;
-  }
-
-  _ReductionTask(this.kind, this.node) {
-    // If new node types are added, they must be marked as deleted in
-    // [[_RemovalRedexVisitor]].
-    assert(node is LetCont || node is LetPrim);
-  }
-
-  bool operator==(_ReductionTask that) {
-    return (that.kind == this.kind && that.node == this.node);
-  }
-
-  String toString() => "$kind: $node";
-}
-
-/// A dummy class used solely to mark nodes as deleted once they are removed
-/// from a term.
-class _DeletedNode extends Node {
-  accept(_) => null;
-}