Distinguish statement and expression foreign code.

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 1303 matching lines @@
 
   HLocalValue get local() => inputs[0];
 
   void prepareGvn() {
     // TODO(floitsch): implement more fine grained side effects.
     setAllSideEffects();
   }
 }
 
 class HForeign extends HInstruction {
+  final bool _isStatement;

[Lasse Reichstein Nielsen, 2012/06/27 08:10:16]

Just make this non-private and final. No need to wrap a final field in a getter.
And make isStatement a getter, obviously :)

[floitsch, 2012/06/27 12:04:43]

Done.

   final DartString code;
   final HType foreignType;
   HForeign(this.code, DartString declaredType, List<HInstruction> inputs)
       : foreignType = computeTypeFromDeclaredType(declaredType),
+        _isStatement = false,
+        super(inputs);
+  HForeign.statement(this.code, List<HInstruction> inputs)
+      : foreignType = HType.UNKNOWN,
+        _isStatement = true,
         super(inputs);
   accept(HVisitor visitor) => visitor.visitForeign(this);
 
   static HType computeTypeFromDeclaredType(DartString declaredType) {
     if (declaredType.slowToString() == 'bool') return HType.BOOLEAN;
     if (declaredType.slowToString() == 'int') return HType.INTEGER;
     if (declaredType.slowToString() == 'double') return HType.DOUBLE;
     if (declaredType.slowToString() == 'num') return HType.NUMBER;
     if (declaredType.slowToString() == 'String') return HType.STRING;
     return HType.UNKNOWN;
   }
 
   HType get guaranteedType() => foreignType;
 
-  // Be conservative and treat all [HForeign] as statements, even
-  // though some are just expressions.
-  bool isStatement() => true;
+  bool isStatement() => _isStatement;
 }
 
 class HForeignNew extends HForeign {
   ClassElement element;
   HForeignNew(this.element, List<HInstruction> inputs)
       : super(const LiteralDartString("new"),
               const LiteralDartString("Object"), inputs);
   accept(HVisitor visitor) => visitor.visitForeignNew(this);
 }
 
@@ skipping 1264 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);
 }