Refactor 'dart:profiler' UserTag API

runtime/vm/intrinsifier_arm.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"  // Needed here to get TARGET_ARCH_ARM.
 #if defined(TARGET_ARCH_ARM)
 
 #include "vm/intrinsifier.h"
 
 #include "vm/assembler.h"
@@ skipping 1705 matching lines @@
 void Intrinsifier::TwoByteString_equality(Assembler* assembler) {
   StringEquality(assembler, kTwoByteStringCid);
 }
 
 
 // On stack: user tag (+0).
 void Intrinsifier::UserTag_makeCurrent(Assembler* assembler) {
   // R1: Isolate.
   Isolate* isolate = Isolate::Current();
   __ LoadImmediate(R1, reinterpret_cast<uword>(isolate));
+  // R2: Current user tag.
+  __ ldr(R2, Address(R1, Isolate::current_tag_offset()));

[zra, 2014/05/06 15:27:24]

Could you load this directly into R0, and get rid of the mov into R0 before the
return?

[Cutch, 2014/05/06 17:00:25]

Done.

   // R0: UserTag.
   __ ldr(R0, Address(SP, + 0 * kWordSize));
   // Set Isolate::current_tag_.
   __ str(R0, Address(R1, Isolate::current_tag_offset()));
   // R0: UserTag's tag.
   __ ldr(R0, FieldAddress(R0, UserTag::tag_offset()));
   // Set Isolate::user_tag_.
   __ str(R0, Address(R1, Isolate::user_tag_offset()));
   // Set return value.
-  const int32_t raw_null = reinterpret_cast<int32_t>(Object::null());
-  __ LoadImmediate(R0, raw_null);
+  __ mov(R0, ShifterOperand(R2));
+  __ Ret();
+}
+
+
+void Intrinsifier::UserTag_defaultTag(Assembler* assembler) {
+  Isolate* isolate = Isolate::Current();
+  // Set return value to default tag address.
+  __ LoadImmediate(R0,
+      reinterpret_cast<uword>(isolate->object_store()) +
+                              ObjectStore::default_tag_offset());
+  __ ldr(R0, Address(R0, 0));
   __ Ret();
 }
 
 
 void Intrinsifier::Profiler_getCurrentTag(Assembler* assembler) {
-  // R1: Isolate.
+  // R1: Default tag address.
   Isolate* isolate = Isolate::Current();
   __ LoadImmediate(R1, reinterpret_cast<uword>(isolate));
   // Set return value to Isolate::current_tag_.
   __ ldr(R0, Address(R1, Isolate::current_tag_offset()));
   __ Ret();
 }
 
-
-void Intrinsifier::Profiler_clearCurrentTag(Assembler* assembler) {
-  // R1: Isolate.
-  Isolate* isolate = Isolate::Current();
-  __ LoadImmediate(R1, reinterpret_cast<uword>(isolate));
-  // Set return value to Isolate::current_tag_.
-  __ ldr(R0, Address(R1, Isolate::current_tag_offset()));
-  // Clear Isolate::current_tag_.
-  const int32_t raw_null = reinterpret_cast<int32_t>(UserTag::null());
-  __ LoadImmediate(R2, raw_null);
-  __ str(R2, Address(R1, Isolate::current_tag_offset()));
-  // Clear Isolate::user_tag_.
-  __ eor(R2, R2, ShifterOperand(R2));
-  __ str(R2, Address(R1, Isolate::user_tag_offset()));
-  __ Ret();
-}
-
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM