Avoid inserting new temporaries because of HTypeConversion nodes.

lib/compiler/implementation/ssa/nodes.dart

 // Copyright (c) 2011, 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.
 
 interface HVisitor<R> {
   R visitAdd(HAdd node);
   R visitBitAnd(HBitAnd node);
   R visitBitNot(HBitNot node);
   R visitBitOr(HBitOr node);
   R visitBitXor(HBitXor node);
@@ skipping 287 matching lines @@
   visitReturn(HReturn node) => visitControlFlow(node);
   visitShiftRight(HShiftRight node) => visitBinaryBitOp(node);
   visitShiftLeft(HShiftLeft node) => visitBinaryBitOp(node);
   visitSubtract(HSubtract node) => visitBinaryArithmetic(node);
   visitStatic(HStatic node) => visitInstruction(node);
   visitStaticStore(HStaticStore node) => visitInstruction(node);
   visitThis(HThis node) => visitParameterValue(node);
   visitThrow(HThrow node) => visitControlFlow(node);
   visitTry(HTry node) => visitControlFlow(node);
   visitTruncatingDivide(HTruncatingDivide node) => visitBinaryArithmetic(node);
-  visitTypeGuard(HTypeGuard node) => visitInstruction(node);
+  visitTypeGuard(HTypeGuard node) => visitCheck(node);
   visitIs(HIs node) => visitInstruction(node);
-  visitTypeConversion(HTypeConversion node) => visitInstruction(node);
+  visitTypeConversion(HTypeConversion node) => visitCheck(node);
 }
 
 class SubGraph {
   // The first and last block of the sub-graph.
   final HBasicBlock start;
   final HBasicBlock end;
 
   const SubGraph(this.start, this.end);
 
   bool contains(HBasicBlock block) {
@@ skipping 627 matching lines @@
   bool typeEquals(other) => other is HBoolify;
   bool dataEquals(HInstruction other) => true;
 }
 
 class HCheck extends HInstruction {
   HCheck(inputs) : super(inputs);
 
   // TODO(floitsch): make class abstract instead of adding an abstract method.
   abstract accept(HVisitor visitor);
 
-  bool isControlFlow() => true;
+  HInstruction get checkedInput() => inputs[0];
 }
 
-class HTypeGuard extends HInstruction {
+class HTypeGuard extends HCheck {
   final int state;
   final HType guardedType;
   bool isOn = false;
   HTypeGuard(this.guardedType, this.state, List<HInstruction> env) : super(env);
 
   void prepareGvn() {
     assert(!hasSideEffects());
     setUseGvn();
   }
 
   HInstruction get guarded() => inputs.last();
+  HInstruction get checkedInput() => guarded;
 
   HType computeTypeFromInputTypes() {
     return isOn ? guardedType : guarded.propagatedType;
   }
 
   HType get guaranteedType() => isOn ? guardedType : HType.UNKNOWN;
 
   bool isControlFlow() => true;
 
   accept(HVisitor visitor) => visitor.visitTypeGuard(this);
   int typeCode() => 1;
   bool typeEquals(other) => other is HTypeGuard;
   bool dataEquals(HTypeGuard other) => guardedType == other.guardedType;
 }
 
 class HBoundsCheck extends HCheck {
   static final int ALWAYS_FALSE = 0;
   static final int FULL_CHECK = 1;
   static final int ALWAYS_ABOVE_ZERO = 2;
   static final int ALWAYS_TRUE = 3;
   /**
    * Details which tests have been done statically during compilation.
    * Default is that all checks must be performed dynamically.
    */
   int staticChecks = FULL_CHECK;
 
   HBoundsCheck(length, index) : super(<HInstruction>[length, index]);
 
-  HInstruction get length() => inputs[0];
-  HInstruction get index() => inputs[1];
+  HInstruction get length() => inputs[1];
+  HInstruction get index() => inputs[0];
+  bool isControlFlow() => true;
 
   void prepareGvn() {
     assert(!hasSideEffects());
     setUseGvn();
   }
 
   HType get guaranteedType() => HType.INTEGER;
 
   accept(HVisitor visitor) => visitor.visitBoundsCheck(this);
   int typeCode() => 2;
   bool typeEquals(other) => other is HBoundsCheck;
   bool dataEquals(HInstruction other) => true;
 }
 
 class HIntegerCheck extends HCheck {
   bool alwaysFalse = false;
 
   HIntegerCheck(value) : super(<HInstruction>[value]);
 
   HInstruction get value() => inputs[0];
+  bool isControlFlow() => true;
 
   void prepareGvn() {
     assert(!hasSideEffects());
     setUseGvn();
   }
 
   HType get guaranteedType() => HType.INTEGER;
 
   accept(HVisitor visitor) => visitor.visitIntegerCheck(this);
   int typeCode() => 3;
@@ skipping 1108 matching lines @@
 
   HInstruction get typeInfoCall() => inputs[1];
 
   HType get guaranteedType() => HType.BOOLEAN;
 
   accept(HVisitor visitor) => visitor.visitIs(this);
 
   toString() => "$expression is $typeExpression";
 }
 
-class HTypeConversion extends HInstruction {
+class HTypeConversion extends HCheck {
   HType type;
   final bool checked;
 
   HTypeConversion(HType this.type,
                   HInstruction input,
                   [bool this.checked = false])
     : super(<HInstruction>[input]) {
       sourceElement = input.sourceElement;
   }
 
   HType get guaranteedType() => type;
 
   accept(HVisitor visitor) => visitor.visitTypeConversion(this);
+
+  bool hasSideEffects() => checked;
 }
 
 /** Non-block-based (aka. traditional) loop information. */
 class HLoopInformation {
   final HBasicBlock header;
   final List<HBasicBlock> blocks;
   final List<HBasicBlock> backEdges;
   final List<LabelElement> labels;
   final TargetElement target;
 
@@ skipping 274 matching lines @@
                        this.catchBlock,
                        this.finallyBlock);
 
   HBasicBlock get start() => body.start;
   HBasicBlock get end() =>
       finallyBlock === null ? catchBlock.end : finallyBlock.end;
 
   bool accept(HStatementInformationVisitor visitor) =>
     visitor.visitTryInfo(this);
 }