ARM64: Optimize AllocateHeapNumber to use STP.

src/arm64/full-codegen-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 4702 matching lines @@
   __ Push(Smi::FromInt(map->instance_size()));
   __ CallRuntime(Runtime::kHiddenAllocateInNewSpace, 1);
   __ Ldr(context_register(),
          MemOperand(fp, StandardFrameConstants::kContextOffset));
 
   __ Bind(&allocated);
   Register map_reg = x1;
   Register result_value = x2;
   Register boolean_done = x3;
   Register empty_fixed_array = x4;
+  Register untagged_result = x5;
   __ Mov(map_reg, Operand(map));
   __ Pop(result_value);
   __ Mov(boolean_done, Operand(isolate()->factory()->ToBoolean(done)));
   __ Mov(empty_fixed_array, Operand(isolate()->factory()->empty_fixed_array()));
   ASSERT_EQ(map->instance_size(), 5 * kPointerSize);
-  // TODO(jbramley): Use Stp if possible.
-  __ Str(map_reg, FieldMemOperand(result, HeapObject::kMapOffset));
-  __ Str(empty_fixed_array,
-         FieldMemOperand(result, JSObject::kPropertiesOffset));
-  __ Str(empty_fixed_array, FieldMemOperand(result, JSObject::kElementsOffset));
-  __ Str(result_value,
-         FieldMemOperand(result,
-                         JSGeneratorObject::kResultValuePropertyOffset));
-  __ Str(boolean_done,
-         FieldMemOperand(result,
-                         JSGeneratorObject::kResultDonePropertyOffset));
+  STATIC_ASSERT(JSObject::kPropertiesOffset + kPointerSize ==
+                JSObject::kElementsOffset);
+  STATIC_ASSERT(JSGeneratorObject::kResultValuePropertyOffset + kPointerSize ==
+                JSGeneratorObject::kResultDonePropertyOffset);
+  __ ObjectUntag(untagged_result, result);
+  __ Str(map_reg, MemOperand(untagged_result, HeapObject::kMapOffset));
+  __ Stp(empty_fixed_array, empty_fixed_array,
+         MemOperand(untagged_result, JSObject::kPropertiesOffset));
+  __ Stp(result_value, boolean_done,
+         MemOperand(untagged_result,
+                    JSGeneratorObject::kResultValuePropertyOffset));
 
   // Only the value field needs a write barrier, as the other values are in the
   // root set.
   __ RecordWriteField(result, JSGeneratorObject::kResultValuePropertyOffset,
                       x10, x11, kLRHasBeenSaved, kDontSaveFPRegs);
 }
 
 
 // TODO(all): I don't like this method.
 // It seems to me that in too many places x0 is used in place of this.
@@ skipping 237 matching lines @@
   return previous_;
 }
 
 
 #undef __
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM64