Abstract out fetching of break_address in debug mode

src/mips64/assembler-mips64.h

 // Copyright (c) 1994-2006 Sun Microsystems Inc.
 // 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.
 //
@@ skipping 542 matching lines @@
   // Distance between start of patched debug break slot and the emitted address
   // to jump to.
   static const int kPatchDebugBreakSlotAddressOffset =  0 * kInstrSize;
 
   // Difference between address of current opcode and value read from pc
   // register.
   static const int kPcLoadDelta = 4;
 
   static const int kPatchDebugBreakSlotReturnOffset = 6 * kInstrSize;
 
+  // Return the code target address of the patch debug break slot
+  inline static Address break_address_from_break_address(Address pc);
+
   // Number of instructions used for the JS return sequence. The constant is
   // used by the debugger to patch the JS return sequence.
   static const int kJSReturnSequenceInstructions = 7;
   static const int kDebugBreakSlotInstructions = 6;
   static const int kDebugBreakSlotLength =
       kDebugBreakSlotInstructions * kInstrSize;
 
 
   // ---------------------------------------------------------------------------
   // Code generation.
@@ skipping 685 matching lines @@
 class EnsureSpace BASE_EMBEDDED {
  public:
   explicit EnsureSpace(Assembler* assembler) {
     assembler->CheckBuffer();
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_ARM_ASSEMBLER_MIPS_H_