[arm64] Use exclusive instructions in exchange

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 <deque>
 #include <list>
 #include <map>
@@ skipping 1341 matching lines @@
 
   // Load word pair with sign extension.
   void ldpsw(const Register& rt, const Register& rt2, const MemOperand& src);
 
   // Load literal to register from a pc relative address.
   void ldr_pcrel(const CPURegister& rt, int imm19);
 
   // Load literal to register.
   void ldr(const CPURegister& rt, const Immediate& imm);
 
+  // Load exclusive byte.
+  void ldxrb(const Register& rt, const Register& rn);
+
+  // Store exclusive byte.
+  void stxrb(const Register& rs, const Register& rt, const Register& rn);
+
+  // Load exclusive half-word.
+  void ldxrh(const Register& rt, const Register& rn);
+
+  // Store exclusive half-word.
+  void stxrh(const Register& rs, const Register& rt, const Register& rn);
+
+  // Load exclusive word.
+  void ldxr(const Register& rt, const Register& rn);
+
+  // Store exclusive word.
+  void stxr(const Register& rs, const Register& rt, const Register& rn);
+
   // Load-acquire word.
   void ldar(const Register& rt, const Register& rn);
 
   // Load-acquire exclusive word.
   void ldaxr(const Register& rt, const Register& rn);
 
   // Store-release word.
   void stlr(const Register& rt, const Register& rn);
 
   // Store-release exclusive word.
@@ skipping 820 matching lines @@
  public:
   explicit EnsureSpace(Assembler* assembler) {
     assembler->CheckBufferSpace();
   }
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_ARM64_ASSEMBLER_ARM64_H_