Recognize logical operations before code generation.

lib/compiler/implementation/ssa/builder.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.
 
 class Interceptors {
   Compiler compiler;
   Interceptors(Compiler this.compiler);
 
   SourceString mapOperatorToMethodName(Operator op) {
     String name = op.source.stringValue;
@@ skipping 1619 matching lines @@
 
 
   void handleLogicalAndOr(void left(), void right(), [bool isAnd = true]) {
     // x && y is transformed into:
     //   t0 = boolify(x);
     //   if (t0) {
     //     t1 = boolify(y);
     //   } else {
     //     t2 = t0;
     //   }
-    //   result = phi(t1, t2);
+    //   result = phi(t1, false);
     //
     // x || y is transformed into:
     //   t0 = boolify(x);
     //   if (not(t0)) {
     //     t1 = boolify(y);
     //   } else {
     //     t2 = t0;
     //   }
-    //   result = phi(t1, t2);
+    //   result = phi(t1, true);
     HInstruction boolifiedLeft;
     HInstruction boolifiedRight;
 
     void visitCondition() {
       left();
       boolifiedLeft = popBoolified();
       HInstruction condition;
       if (isAnd) {
         condition = boolifiedLeft;
       } else {
         condition = new HNot(boolifiedLeft);
         add(condition);
       }
       stack.add(condition);
     }
 
     void visitThen() {
       right();
       boolifiedRight = popBoolified();
     }
 
     handleIf(visitCondition, visitThen, null);
     HPhi result = new HPhi.manyInputs(null,
-        <HInstruction>[boolifiedRight, boolifiedLeft]);
+        <HInstruction>[boolifiedRight, graph.addConstantBool(!isAnd)]);
     current.addPhi(result);
     stack.add(result);
   }
 
   void visitLogicalNot(Send node) {
     assert(node.argumentsNode is Prefix);
     visit(node.receiver);
     HNot not = new HNot(popBoolified());
     push(not);
   }
@@ skipping 1730 matching lines @@
                                    <HInstruction>[target, input],
                                    HType.STRING));
     return builder.pop();
   }
 
   HInstruction result(Node node) {
     flushLiterals(node);
     return prefix;
   }
 }