Support non-speculative type propagation.

frog/leg/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 824 matching lines @@
     return candidateType;
   }
 
   HType computeDesiredInputType(HInstruction input) => HType.UNKNOWN;
 
   // Returns whether the instruction does produce the type it claims.
   // For most instructions, this returns false. A type guard will be
   // inserted to make sure the users get the right type in.
   bool hasExpectedType() => false;
 
-  // Re-compute and update the type of the instruction. Returns
-  // whether or not the type was changed.
-  bool updateType() {
-    if (type.isConflicting()) return false;
-    HType newType = computeType();
-    HType desiredType = computeDesiredType();
-    HType combined = newType.combine(desiredType);
-    if (combined.isKnown()) newType = combined;
-
-    bool changed = (type != newType);
-    if (type.isUnknown()) {
-      type = newType;
-      return changed;
-    } else if (changed) {
-      type = type.combine(newType);
-      return changed;
-    }
-    return false;
-  }
-
   bool isInBasicBlock() => block !== null;
 
   String inputsToString() {
     void addAsCommaSeparated(StringBuffer buffer, List<HInstruction> list) {
       for (int i = 0; i < list.length; i++) {
         if (i != 0) buffer.add(', ');
         buffer.add("@${list[i].id}");
       }
     }
 
@@ skipping 918 matching lines @@
     return type;
   }
 
   bool hasExpectedType() {
     for (int i = 0; i < inputs.length; i++) {
       if (type.combine(inputs[i].type).isConflicting()) return false;
     }
     return true;
   }
 
-  void setInitialTypeForLoopPhi() {
-    assert(block.isLoopHeader());
-    assert(type.isUnknown());
-    type = inputs[0].type;
-  }
-
   bool isLogicalOperator() => logicalOperatorType != IS_NOT_LOGICAL_OPERATOR;
 
   String logicalOperator() {
     assert(isLogicalOperator());
     if (logicalOperatorType == IS_AND) return "&&";
     assert(logicalOperatorType == IS_OR);
     return "||";
   }
 
   toString() => 'phi';
@@ skipping 255 matching lines @@
 class HIfBlockInformation {
   final HIf branch;
   final SubGraph thenGraph;
   final SubGraph elseGraph;
   final HBasicBlock joinBlock;
   HIfBlockInformation(this.branch,
                       this.thenGraph,
                       this.elseGraph,
                       this.joinBlock);
 }