Prevent hoisting of certain check nodes, including [HTypeKnown].

sdk/lib/_internal/compiler/implementation/ssa/nodes.dart

 // Copyright (c) 2012, 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 ssa;
 
 abstract class HVisitor<R> {
   R visitAdd(HAdd node);
   R visitBitAnd(HBitAnd node);
   R visitBitNot(HBitNot node);
@@ skipping 798 matching lines @@
       : id = idCounter++, usedBy = <HInstruction>[] {
     assert(inputs.every((e) => e != null));
   }
 
   int get hashCode => id;
 
   bool useGvn() => _useGvn;
   void setUseGvn() { _useGvn = true; }
   void clearUseGvn() { _useGvn = false; }
 
+  bool get isMovable => useGvn();
+
   /**
    * A pure instruction is an instruction that does not have any side
    * effect, nor any dependency. They can be moved anywhere in the
    * graph.
    */
   bool isPure() {
     return !sideEffects.hasSideEffects()
         && !sideEffects.dependsOnSomething()
         && !canThrow();
   }
@@ skipping 1628 matching lines @@
   bool isJsStatement() => isControlFlow();
   bool isControlFlow() => isArgumentTypeCheck || isReceiverTypeCheck;
 
   int typeCode() => HInstruction.TYPE_CONVERSION_TYPECODE;
   bool typeEquals(HInstruction other) => other is HTypeConversion;
   bool isCodeMotionInvariant() => false;
 
   bool dataEquals(HTypeConversion other) {
     return kind == other.kind
         && typeExpression == other.typeExpression
-        && checkedType == other.checkedType;
+        && checkedType == other.checkedType
+        && receiverTypeCheckSelector == other.receiverTypeCheckSelector;
   }
 }
 
 /// The [HTypeKnown] instruction marks a value with a refined type.
 class HTypeKnown extends HCheck {
   TypeMask knownType;
-  HTypeKnown(TypeMask knownType, HInstruction input)
+  bool _isMovable;
+
+  HTypeKnown.pinned(TypeMask knownType, HInstruction input)
       : this.knownType = knownType,
+        this._isMovable = false,
         super(<HInstruction>[input], knownType);
+
+  HTypeKnown.witnessed(TypeMask knownType, HInstruction input,
+                       HInstruction witness)
+      : this.knownType = knownType,
+        this._isMovable = true,
+        super(<HInstruction>[input, witness], knownType);
+
   toString() => 'TypeKnown $knownType';
   accept(HVisitor visitor) => visitor.visitTypeKnown(this);
 
   bool isJsStatement() => false;
   bool isControlFlow() => false;
   bool canThrow() => false;
 
   int typeCode() => HInstruction.TYPE_KNOWN_TYPECODE;
   bool typeEquals(HInstruction other) => other is HTypeKnown;
   bool isCodeMotionInvariant() => true;
+  bool get isMovable => _isMovable && useGvn();
 
   bool dataEquals(HTypeKnown other) {
     return knownType == other.knownType
         && instructionType == other.instructionType;
   }
 }
 
 class HRangeConversion extends HCheck {
   HRangeConversion(HInstruction input, type)
       : super(<HInstruction>[input], type) {
     sourceElement = input.sourceElement;
   }
+
+  bool get isMovable => false;
+
   accept(HVisitor visitor) => visitor.visitRangeConversion(this);
 }
 
 class HStringConcat extends HInstruction {
   final ast.Node node;
   HStringConcat(HInstruction left, HInstruction right, this.node, TypeMask type)
       : super(<HInstruction>[left, right], type) {
     // TODO(sra): Until Issue 9293 is fixed, this false dependency keeps the
     // concats bunched with stringified inputs for much better looking code with
     // fewer temps.
@@ skipping 440 matching lines @@
 class HDynamicType extends HRuntimeType {
   HDynamicType(DynamicType dartType, TypeMask instructionType)
       : super(const <HInstruction>[], dartType, instructionType);
 
   accept(HVisitor visitor) => visitor.visitDynamicType(this);
 
   int typeCode() => HInstruction.DYNAMIC_TYPE_TYPECODE;
 
   bool typeEquals(HInstruction other) => other is HDynamicType;
 }