Fix potential overwriting of debug jumps of following code.

src/x64/macro-assembler-x64.h

 // Copyright 2010 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 56 matching lines @@
   ScaleFactor scale;
 };
 
 // MacroAssembler implements a collection of frequently used macros.
 class MacroAssembler: public Assembler {
  public:
   MacroAssembler(void* buffer, int size);
 
   void LoadRoot(Register destination, Heap::RootListIndex index);
   void CompareRoot(Register with, Heap::RootListIndex index);
-  void CompareRoot(Operand with, Heap::RootListIndex index);
+  void CompareRoot(const Operand& with, Heap::RootListIndex index);
   void PushRoot(Heap::RootListIndex index);
   void StoreRoot(Register source, Heap::RootListIndex index);
 
   // ---------------------------------------------------------------------------
   // GC Support
 
   // For page containing |object| mark region covering |addr| dirty.
   // RecordWriteHelper only works if the object is not in new
   // space.
   void RecordWriteHelper(Register object,
@@ skipping 501 matching lines @@
 
   // Control Flow
   void Jump(Address destination, RelocInfo::Mode rmode);
   void Jump(ExternalReference ext);
   void Jump(Handle<Code> code_object, RelocInfo::Mode rmode);
 
   void Call(Address destination, RelocInfo::Mode rmode);
   void Call(ExternalReference ext);
   void Call(Handle<Code> code_object, RelocInfo::Mode rmode);
 
+  // Emit call to the code we are currently generating.
+  void CallSelf() {
+    Handle<Code> self(reinterpret_cast<Code**>(CodeObject().location()));
+    Call(self, RelocInfo::CODE_TARGET);
+  }
+
   // Non-x64 instructions.
   // Push/pop all general purpose registers.
   // Does not push rsp/rbp nor any of the assembler's special purpose registers
   // (kScratchRegister, kSmiConstantRegister, kRootRegister).
   void Pushad();
   void Popad();
   // Sets the stack as after performing Popad, without actually loading the
   // registers.
   void Dropad();
 
@@ skipping 1156 matching lines @@
       Call(adaptor, RelocInfo::CODE_TARGET);
       jmp(done);
     } else {
       Jump(adaptor, RelocInfo::CODE_TARGET);
     }
     bind(&invoke);
   }
 }
 
 
+// Ensures that code is padded to at least a given size.
+class Padding BASE_EMBEDDED {
+ public:
+  Padding(Assembler* masm, int min_size)
+      : masm_(masm), min_end_offset_(masm->pc_offset() + min_size) { }
+  ~Padding() {
+    int offset = masm_->pc_offset();
+    if (offset < min_end_offset_) {
+      masm_->Pad(min_end_offset_ - offset);
+    }
+  }
+ private:
+  Assembler* masm_;
+  int min_end_offset_;
+};
+
+
 } }  // namespace v8::internal
 
 #endif  // V8_X64_MACRO_ASSEMBLER_X64_H_