X87: [Atomics] Make Atomics.store a builtin using TF.

src/x87/assembler-x87.cc

 // 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 534 matching lines @@
   }
 }
 
 
 void Assembler::xchg(Register dst, const Operand& src) {
   EnsureSpace ensure_space(this);
   EMIT(0x87);
   emit_operand(dst, src);
 }
 
+void Assembler::xchg_b(Register reg, const Operand& op) {
+  EnsureSpace ensure_space(this);
+  EMIT(0x86);
+  emit_operand(reg, op);
+}
+
+void Assembler::xchg_w(Register reg, const Operand& op) {
+  EnsureSpace ensure_space(this);
+  EMIT(0x66);
+  EMIT(0x87);
+  emit_operand(reg, op);
+}
 
 void Assembler::adc(Register dst, int32_t imm32) {
   EnsureSpace ensure_space(this);
   emit_arith(2, Operand(dst), Immediate(imm32));
 }
 
 
 void Assembler::adc(Register dst, const Operand& src) {
   EnsureSpace ensure_space(this);
   EMIT(0x13);
@@ skipping 1607 matching lines @@
     fflush(coverage_log);
   }
 }
 
 #endif
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_X87