ARM64: Optimize AllocateHeapNumber to use STP.

src/arm64/code-stubs-arm64.cc

 // 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 1375 matching lines @@
 
   if (exponent_type_ == ON_STACK) {
     // Bail out to runtime code.
     __ Bind(&call_runtime);
     // Put the arguments back on the stack.
     __ Push(base_tagged, exponent_tagged);
     __ TailCallRuntime(Runtime::kHiddenMathPow, 2, 1);
 
     // Return.
     __ Bind(&done);
-    __ AllocateHeapNumber(result_tagged, &call_runtime, scratch0, scratch1);
-    __ Str(result_double,
-        FieldMemOperand(result_tagged, HeapNumber::kValueOffset));
+    __ AllocateHeapNumber(result_tagged, &call_runtime, scratch0, scratch1,
+                          result_double);
     ASSERT(result_tagged.is(x0));
     __ IncrementCounter(
         masm->isolate()->counters()->math_pow(), 1, scratch0, scratch1);
     __ Ret();
   } else {
     AllowExternalCallThatCantCauseGC scope(masm);
     __ Mov(saved_lr, lr);
     __ Fmov(base_double, base_double_copy);
     __ Scvtf(exponent_double, exponent_integer);
     __ CallCFunction(
@@ skipping 4325 matching lines @@
                               MemOperand(fp, 6 * kPointerSize),
                               NULL);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM64