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 931 matching lines @@
   }
 
   // Number of instructions generated for the return sequence in
   // FullCodeGenerator::EmitReturnSequence.
   static const int kJSRetSequenceInstructions = 7;
   // Distance between start of patched return sequence and the emitted address
   // to jump to.
   static const int kPatchReturnSequenceAddressOffset =  0;
   static const int kPatchDebugBreakSlotAddressOffset =  0;
 
+  // Return the code target address of the patch debug break slot
+  inline static Address break_address_from_break_address(Address pc);
+
   // Number of instructions necessary to be able to later patch it to a call.
   // See DebugCodegen::GenerateSlot() and
   // BreakLocationIterator::SetDebugBreakAtSlot().
   static const int kDebugBreakSlotInstructions = 4;
   static const int kDebugBreakSlotLength =
     kDebugBreakSlotInstructions * kInstructionSize;
 
   static const int kPatchDebugBreakSlotReturnOffset = 2 * kInstructionSize;
 
   // Prevent contant pool emission until EndBlockConstPool is called.
@@ skipping 1334 matching lines @@
 class EnsureSpace BASE_EMBEDDED {
  public:
   explicit EnsureSpace(Assembler* assembler) {
     assembler->CheckBufferSpace();
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_ARM64_ASSEMBLER_ARM64_H_