Implements type checking in MIPS needed for FindCodeObject test.

runtime/vm/assembler_mips.cc

Index: runtime/vm/assembler_mips.cc
===================================================================
--- runtime/vm/assembler_mips.cc	(revision 20924)
+++ runtime/vm/assembler_mips.cc	(working copy)
@@ -131,6 +131,41 @@
 }
 
 
+void Assembler::LoadClassId(Register result, Register object) {
+  ASSERT(RawObject::kClassIdTagBit == 16);
+  ASSERT(RawObject::kClassIdTagSize == 16);
+  const intptr_t class_id_offset = Object::tags_offset() +
+      RawObject::kClassIdTagBit / kBitsPerByte;
+  lhu(result, FieldAddress(object, class_id_offset));
+}
+
+
+void Assembler::LoadClassById(Register result, Register class_id) {
+  ASSERT(result != class_id);
+  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, class_id, 2);
+  addu(result, result, TMP);
+  lw(result, Address(result));
+}
+
+
+void Assembler::LoadClass(Register result, Register object, Register scratch) {
+  ASSERT(scratch != result);
+  LoadClassId(scratch, object);
+
+  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(scratch, scratch, 2);
+  addu(result, result, scratch);
+  lw(result, Address(result));
+}
+
+
 void Assembler::EnterStubFrame() {
   addiu(SP, SP, Immediate(-3 * kWordSize));
   sw(ZR, Address(SP, 2 * kWordSize));  // PC marker is 0 in stubs.