Add ability to do "else-if" clauses in IfBuilder

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 935 matching lines @@
 
   HArgumentsObject* arguments_object_;
   HArgumentsElements* arguments_elements_;
 
   FunctionState* outer_;
 };
 
 
 class HIfContinuation V8_FINAL {
  public:
-  HIfContinuation() : continuation_captured_(false) {}
+  HIfContinuation()
+    : continuation_captured_(false),
+      true_branch_(NULL),
+      false_branch_(NULL) {}
   HIfContinuation(HBasicBlock* true_branch,
                   HBasicBlock* false_branch)
       : continuation_captured_(true), true_branch_(true_branch),
         false_branch_(false_branch) {}
   ~HIfContinuation() { ASSERT(!continuation_captured_); }
 
   void Capture(HBasicBlock* true_branch,
                HBasicBlock* false_branch) {
     ASSERT(!continuation_captured_);
     true_branch_ = true_branch;
@@ skipping 519 matching lines @@
     //   // continues after else code of if_whatever or if_something.
     //   ...
     //   if_finally.End();
     void JoinContinuation(HIfContinuation* continuation);
 
     void Then();
     void Else();
     void End();
 
     void Deopt(const char* reason);
+    void ThenDeopt(const char* reason) {
+      Then();
+      Deopt(reason);
+    }
     void ElseDeopt(const char* reason) {
       Else();
       Deopt(reason);
     }
 
     void Return(HValue* value);
 
    private:
     HControlInstruction* AddCompare(HControlInstruction* compare);
 
     HGraphBuilder* builder() const { return builder_; }
 
+    void AddMergeAtJoinBlock(bool deopt);
+
+    void Finish();
+    void Finish(HBasicBlock** then_continuation,
+                HBasicBlock** else_continuation);
+
+    class MergeAtJoinBlock : public ZoneObject {
+     public:
+      MergeAtJoinBlock(HBasicBlock* block,
+                       bool deopt,
+                       MergeAtJoinBlock* next)
+        : block_(block),
+          deopt_(deopt),
+          next_(next) {}
+      HBasicBlock* block_;
+      bool deopt_;
+      MergeAtJoinBlock* next_;
+    };
+
     HGraphBuilder* builder_;
     bool finished_ : 1;
-    bool deopt_then_ : 1;
-    bool deopt_else_ : 1;
     bool did_then_ : 1;
     bool did_else_ : 1;
+    bool did_else_if_ : 1;
     bool did_and_ : 1;
     bool did_or_ : 1;
     bool captured_ : 1;
     bool needs_compare_ : 1;
+    bool pending_merge_block_ : 1;
     HBasicBlock* first_true_block_;
-    HBasicBlock* last_true_block_;
     HBasicBlock* first_false_block_;
     HBasicBlock* split_edge_merge_block_;
-    HBasicBlock* merge_block_;
+    MergeAtJoinBlock* merge_at_join_blocks_;
+    int normal_merge_at_join_block_count_;
+    int deopt_merge_at_join_block_count_;
   };
 
   class LoopBuilder V8_FINAL {
    public:
     enum Direction {
       kPreIncrement,
       kPostIncrement,
       kPreDecrement,
       kPostDecrement
     };
@@ skipping 1003 matching lines @@
   }
 
  private:
   HGraphBuilder* builder_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_H_