Abstract out fetching of break_address in debug mode

src/arm64/assembler-arm64.h

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_ARM64_ASSEMBLER_ARM64_H_
 #define V8_ARM64_ASSEMBLER_ARM64_H_
 
 #include <list>
 #include <map>
 #include <vector>
@@ skipping 869 matching lines @@
                                                FLUSH_ICACHE_IF_NEEDED);
 
   // Return the code target address at a call site from the return address of
   // that call in the instruction stream.
   inline static Address target_address_from_return_address(Address pc);
 
   // Given the address of the beginning of a call, return the address in the
   // instruction stream that call will return from.
   inline static Address return_address_from_call_start(Address pc);
 
+  // Return the code target address of the patch debug break slot
+  inline static Address break_address_from_return_address(Address pc);
+
   // This sets the branch destination (which is in the constant pool on ARM).
   // This is for calls and branches within generated code.
   inline static void deserialization_set_special_target_at(
       Address constant_pool_entry, Code* code, Address target);
 
   // All addresses in the constant pool are the same size as pointers.
   static const int kSpecialTargetSize = kPointerSize;
 
   // The sizes of the call sequences emitted by MacroAssembler::Call.
   // Wherever possible, use MacroAssembler::CallSize instead of these constants,
@@ skipping 1396 matching lines @@
 class EnsureSpace BASE_EMBEDDED {
  public:
   explicit EnsureSpace(Assembler* assembler) {
     assembler->CheckBufferSpace();
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_ARM64_ASSEMBLER_ARM64_H_