Handle switch effects

src/ast.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 241 matching lines @@
 
   friend class CaseClause;  // Generates AST IDs.
 };
 
 
 class Statement: public AstNode {
  public:
   Statement() : statement_pos_(RelocInfo::kNoPosition) {}
 
   bool IsEmpty() { return AsEmptyStatement() != NULL; }
+  virtual bool IsJump() const { return false; }
 
   void set_statement_pos(int statement_pos) { statement_pos_ = statement_pos; }
   int statement_pos() const { return statement_pos_; }
 
  private:
   int statement_pos_;
 };
 
 
 class SmallMapList {
@@ skipping 180 matching lines @@
  public:
   DECLARE_NODE_TYPE(Block)
 
   void AddStatement(Statement* statement, Zone* zone) {
     statements_.Add(statement, zone);
   }
 
   ZoneList<Statement*>* statements() { return &statements_; }
   bool is_initializer_block() const { return is_initializer_block_; }
 
+  virtual bool IsJump() const {
+    return !statements_.is_empty() && statements_.last()->IsJump()
+        && labels()->is_empty();  // Good enough as an approximation...
+  }
+
   Scope* scope() const { return scope_; }
   void set_scope(Scope* scope) { scope_ = scope; }
 
  protected:
   Block(Isolate* isolate,
         ZoneStringList* labels,
         int capacity,
         bool is_initializer_block,
         Zone* zone)
       : BreakableStatement(isolate, labels, TARGET_FOR_NAMED_ONLY),
@@ skipping 530 matching lines @@
   const BailoutId back_edge_id_;
 };
 
 
 class ExpressionStatement: public Statement {
  public:
   DECLARE_NODE_TYPE(ExpressionStatement)
 
   void set_expression(Expression* e) { expression_ = e; }
   Expression* expression() const { return expression_; }
+  virtual bool IsJump() const { return expression_->IsThrow(); }
 
  protected:
   explicit ExpressionStatement(Expression* expression)
       : expression_(expression) { }
 
  private:
   Expression* expression_;
 };
 
 
-class ContinueStatement: public Statement {
+class JumpStatement: public Statement {
+ public:
+  virtual bool IsJump() const { return true; }
+
+ protected:
+  JumpStatement() {}
+};
+
+
+class ContinueStatement: public JumpStatement {

[titzer, 2013/07/15 09:18:18]

You could also just implement IsJump() in the subclasses.

[rossberg, 2013/07/15 09:44:59]

Yeah, but I thought this could be conceptually useful. But maybe not. Does it
harm, though?

  public:
   DECLARE_NODE_TYPE(ContinueStatement)
 
   IterationStatement* target() const { return target_; }
 
  protected:
   explicit ContinueStatement(IterationStatement* target)
       : target_(target) { }
 
  private:
   IterationStatement* target_;
 };
 
 
-class BreakStatement: public Statement {
+class BreakStatement: public JumpStatement {
  public:
   DECLARE_NODE_TYPE(BreakStatement)
 
   BreakableStatement* target() const { return target_; }
 
  protected:
   explicit BreakStatement(BreakableStatement* target)
       : target_(target) { }
 
  private:
   BreakableStatement* target_;
 };
 
 
-class ReturnStatement: public Statement {
+class ReturnStatement: public JumpStatement {
  public:
   DECLARE_NODE_TYPE(ReturnStatement)
 
   Expression* expression() const { return expression_; }
 
  protected:
   explicit ReturnStatement(Expression* expression)
       : expression_(expression) { }
 
  private:
@@ skipping 98 matching lines @@
  public:
   DECLARE_NODE_TYPE(IfStatement)
 
   bool HasThenStatement() const { return !then_statement()->IsEmpty(); }
   bool HasElseStatement() const { return !else_statement()->IsEmpty(); }
 
   Expression* condition() const { return condition_; }
   Statement* then_statement() const { return then_statement_; }
   Statement* else_statement() const { return else_statement_; }
 
+  virtual bool IsJump() const {
+    return HasThenStatement() && then_statement()->IsJump()
+        && HasElseStatement() && else_statement()->IsJump();
+  }
+
   BailoutId IfId() const { return if_id_; }
   BailoutId ThenId() const { return then_id_; }
   BailoutId ElseId() const { return else_id_; }
 
  protected:
   IfStatement(Isolate* isolate,
               Expression* condition,
               Statement* then_statement,
               Statement* else_statement)
       : condition_(condition),
@@ skipping 2028 matching lines @@
  private:
   Isolate* isolate_;
   Zone* zone_;
   Visitor visitor_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_AST_H_