Abstract out fetching of break_address in debug mode

src/arm64/assembler-arm64-inl.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_INL_H_
 #define V8_ARM64_ASSEMBLER_ARM64_INL_H_
 
 #include "src/arm64/assembler-arm64.h"
 #include "src/assembler.h"
 #include "src/debug.h"
@@ skipping 589 matching lines @@
   //  ldr ip0, #... @ load from literal pool
   //  blr ip0
   Address candidate = pc - 2 * kInstructionSize;
   Instruction* instr = reinterpret_cast<Instruction*>(candidate);
   USE(instr);
   ASSERT(instr->IsLdrLiteralX());
   return candidate;
 }
 
 
+Address Assembler::break_address_from_return_address(Address pc) {
+  return pc - Assembler::kPatchDebugBreakSlotReturnOffset;
+}
+
+
 Address Assembler::return_address_from_call_start(Address pc) {
   // The call, generated by MacroAssembler::Call, is one of two possible
   // sequences:
   //
   // Without relocation:
   //  movz  temp, #(target & 0x000000000000ffff)
   //  movk  temp, #(target & 0x00000000ffff0000)
   //  movk  temp, #(target & 0x0000ffff00000000)
   //  blr   temp
   //
@@ skipping 638 matching lines @@
 
 
 void Assembler::ClearRecordedAstId() {
   recorded_ast_id_ = TypeFeedbackId::None();
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_ARM64_ASSEMBLER_ARM64_INL_H_