Support fast case for-in in Crankshaft.

src/hydrogen.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 687 matching lines @@
 class HGraphBuilder: public AstVisitor {
  public:
   enum BreakType { BREAK, CONTINUE };
   enum SwitchType { UNKNOWN_SWITCH, SMI_SWITCH, STRING_SWITCH };
 
   // A class encapsulating (lazily-allocated) break and continue blocks for
   // a breakable statement.  Separated from BreakAndContinueScope so that it
   // can have a separate lifetime.
   class BreakAndContinueInfo BASE_EMBEDDED {
    public:
-    explicit BreakAndContinueInfo(BreakableStatement* target)
-      : target_(target), break_block_(NULL), continue_block_(NULL) {
+    explicit BreakAndContinueInfo(BreakableStatement* target,
+                                  int drop_extra = 0)
+        : target_(target),
+          break_block_(NULL),
+          continue_block_(NULL),
+          drop_extra_(drop_extra) {
     }
 
     BreakableStatement* target() { return target_; }
     HBasicBlock* break_block() { return break_block_; }
     void set_break_block(HBasicBlock* block) { break_block_ = block; }
     HBasicBlock* continue_block() { return continue_block_; }
     void set_continue_block(HBasicBlock* block) { continue_block_ = block; }
+    int drop_extra() { return drop_extra_; }
 
    private:
     BreakableStatement* target_;
     HBasicBlock* break_block_;
     HBasicBlock* continue_block_;
+    int drop_extra_;
   };
 
   // A helper class to maintain a stack of current BreakAndContinueInfo
   // structures mirroring BreakableStatement nesting.
   class BreakAndContinueScope BASE_EMBEDDED {
    public:
     BreakAndContinueScope(BreakAndContinueInfo* info, HGraphBuilder* owner)
         : info_(info), owner_(owner), next_(owner->break_scope()) {
       owner->set_break_scope(this);
     }
 
     ~BreakAndContinueScope() { owner_->set_break_scope(next_); }
 
     BreakAndContinueInfo* info() { return info_; }
     HGraphBuilder* owner() { return owner_; }
     BreakAndContinueScope* next() { return next_; }
 
     // Search the break stack for a break or continue target.
-    HBasicBlock* Get(BreakableStatement* stmt, BreakType type);
+    HBasicBlock* Get(BreakableStatement* stmt, BreakType type, int* drop_extra);
 
    private:
     BreakAndContinueInfo* info_;
     HGraphBuilder* owner_;
     BreakAndContinueScope* next_;
   };
 
   HGraphBuilder(CompilationInfo* info, TypeFeedbackOracle* oracle);
 
   HGraph* CreateGraph();
@@ skipping 552 matching lines @@
   const char* filename_;
   HeapStringAllocator string_allocator_;
   StringStream trace_;
   int indent_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_H_