Track fields which are known to be always set to integer constants

lib/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.
 
 interface HVisitor<R> {
   R visitAdd(HAdd node);
   R visitBitAnd(HBitAnd node);
   R visitBitNot(HBitNot node);
   R visitBitOr(HBitOr node);
   R visitBitXor(HBitXor node);
@@ skipping 97 matching lines @@
     currentBlock = node;
     visitInstructionList(node);
   }
 }
 
 class HGraph {
   HBasicBlock entry;
   HBasicBlock exit;
   bool isRecursiveMethod = false;
   bool calledInLoop = false;
+  bool highTypeLikelyhood = false;
   final List<HBasicBlock> blocks;
 
   // We canonicalize all constants used within a graph so we do not
   // have to worry about them for global value numbering.
   Map<Constant, HConstant> constants;
 
   HGraph()
       : blocks = new List<HBasicBlock>(),
         constants = new Map<Constant, HConstant>() {
     entry = addNewBlock();
@@ skipping 1660 matching lines @@
 
   toString() => 'literal: $constant';
   accept(HVisitor visitor) => visitor.visitConstant(this);
 
   HType get guaranteedType() => constantType;
 
   bool isConstant() => true;
   bool isConstantBoolean() => constant.isBool();
   bool isConstantNull() => constant.isNull();
   bool isConstantNumber() => constant.isNum();
+  bool isConstantInteger() => constant.isInt();
   bool isConstantString() => constant.isString();
   bool isConstantList() => constant.isList();
   bool isConstantMap() => constant.isMap();
   bool isConstantFalse() => constant.isFalse();
   bool isConstantTrue() => constant.isTrue();
 
   // Maybe avoid this if the literal is big?
   bool isCodeMotionInvariant() => true;
 }
 
@@ skipping 776 matching lines @@
   HBasicBlock get start() => expression.start;
   HBasicBlock get end() {
     // We don't create a switch block if there are no cases.
     assert(!statements.isEmpty());
     return statements.last().end;
   }
 
   bool accept(HStatementInformationVisitor visitor) =>
       visitor.visitSwitchInfo(this);
 }