Add LoadTaggedClassIdMayBeSmi to assembly and improve performance of inline cache stubs.

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"
 #if defined(TARGET_ARCH_MIPS)
 
 #include "vm/assembler.h"
 #include "vm/longjump.h"
 #include "vm/runtime_entry.h"
@@ skipping 634 matching lines @@
   lw(result, FieldAddress(CTX, Context::isolate_offset()));
   const intptr_t table_offset_in_isolate =
       Isolate::class_table_offset() + ClassTable::table_offset();
   lw(result, Address(result, table_offset_in_isolate));
   sll(TMP, TMP, 2);
   addu(result, result, TMP);
   lw(result, Address(result));
 }
 
 
+void Assembler::LoadTaggedClassIdMayBeSmi(Register result, Register object) {
+  Label load, done;
+  andi(CMPRES1, object, Immediate(kSmiTagMask));
+  bne(CMPRES1, ZR, &load);
+  LoadImmediate(result, Smi::RawValue(kSmiCid));
+  b(&done);
+  Bind(&load);
+  LoadClassId(result, object);
+  SmiTag(result);
+  Bind(&done);
+}
+
+
 void Assembler::EnterFrame() {
   ASSERT(!in_delay_slot_);
   addiu(SP, SP, Immediate(-2 * kWordSize));
   sw(RA, Address(SP, 1 * kWordSize));
   sw(FP, Address(SP, 0 * kWordSize));
   mov(FP, SP);
 }
 
 
 void Assembler::LeaveFrameAndReturn() {
@@ skipping 425 matching lines @@
     Emit(reinterpret_cast<int32_t>(message));
     Bind(&msg);
     break_(Instr::kMsgMessageCode);
   }
 #endif
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_MIPS