ARM & MIPS: Don't embed an address in the general class id fetch.

runtime/vm/assembler_mips.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"  // NOLINT
 #if defined(TARGET_ARCH_MIPS)
 
 #include "vm/assembler.h"
 #include "vm/longjump.h"
 #include "vm/runtime_entry.h"
@@ skipping 731 matching lines @@
 
 void Assembler::LoadClass(Register result, Register object) {
   ASSERT(!in_delay_slot_);
   ASSERT(TMP != result);
   LoadClassId(TMP, object);
   LoadClassById(result, TMP);
 }
 
 
 void Assembler::LoadClassIdMayBeSmi(Register result, Register object) {
-  static const intptr_t kSmiCidSource = kSmiCid << RawObject::kClassIdTagPos;
-
-  LoadImmediate(TMP, reinterpret_cast<int32_t>(&kSmiCidSource) + 1);
+  Label heap_object, done;
   andi(CMPRES1, object, Immediate(kSmiTagMask));
-  if (result != object) {
-    mov(result, object);
-  }
-  movz(result, TMP, CMPRES1);
-  LoadClassId(result, result);
+  bne(CMPRES1, ZR, &heap_object);
+  LoadImmediate(result, kSmiCid);
+  b(&done);
+  Bind(&heap_object);
+  LoadClassId(result, object);
+  Bind(&done);
 }
 
 
 void Assembler::LoadTaggedClassIdMayBeSmi(Register result, Register object) {
   LoadClassIdMayBeSmi(result, object);
   SmiTag(result);
 }
 
 
 void Assembler::ComputeRange(Register result,
@@ skipping 564 matching lines @@
   Label stop;
   b(&stop);
   Emit(reinterpret_cast<int32_t>(message));
   Bind(&stop);
   break_(Instr::kStopMessageCode);
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_MIPS