A64: When truncating to an int, store the result in a 64bit register

src/a64/macro-assembler-a64.h

 // Copyright 2013 the V8 project authors. 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.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1076 matching lines @@
   void InvokeFunction(Handle<JSFunction> function,
                       const ParameterCount& expected,
                       const ParameterCount& actual,
                       InvokeFlag flag,
                       const CallWrapper& call_wrapper);
 
 
   // ---- Floating point helpers ----
 
   enum ECMA262ToInt32Result {
-    // Provide an untagged int32_t which can be read using result.W(). That is,
-    // the upper 32 bits of result are undefined.
-    INT32_IN_W,
-
     // Provide an untagged int32_t which can be read using the 64-bit result
     // register. The int32_t result is sign-extended.
-    INT32_IN_X,
+    INT32,
 
     // Tag the int32_t result as a smi.
     SMI
   };
 
   // Applies ECMA-262 ToInt32 (see section 9.5) to a double value.
   void ECMA262ToInt32(Register result,
                       DoubleRegister input,
                       Register scratch1,
                       Register scratch2,
-                      ECMA262ToInt32Result format = INT32_IN_X);
+                      ECMA262ToInt32Result format = INT32);
 
   // As ECMA262ToInt32, but operate on a HeapNumber.
   void HeapNumberECMA262ToInt32(Register result,
                                 Register heap_number,
                                 Register scratch1,
                                 Register scratch2,
                                 DoubleRegister double_scratch,
-                                ECMA262ToInt32Result format = INT32_IN_X);
+                                ECMA262ToInt32Result format = INT32);
 
   // ---- Code generation helpers ----
 
   void set_generating_stub(bool value) { generating_stub_ = value; }
   bool generating_stub() const { return generating_stub_; }
 #if DEBUG
   void set_allow_macro_instructions(bool value) {
     allow_macro_instructions_ = value;
   }
   bool allow_macro_instructions() const { return allow_macro_instructions_; }
@@ skipping 1050 matching lines @@
 #error "Unsupported option"
 #define CODE_COVERAGE_STRINGIFY(x) #x
 #define CODE_COVERAGE_TOSTRING(x) CODE_COVERAGE_STRINGIFY(x)
 #define __FILE_LINE__ __FILE__ ":" CODE_COVERAGE_TOSTRING(__LINE__)
 #define ACCESS_MASM(masm) masm->stop(__FILE_LINE__); masm->
 #else
 #define ACCESS_MASM(masm) masm->
 #endif
 
 #endif  // V8_A64_MACRO_ASSEMBLER_A64_H_