Support checked mode for VM tests on ARM.

runtime/vm/assembler_arm.cc

Index: runtime/vm/assembler_arm.cc
===================================================================
--- runtime/vm/assembler_arm.cc	(revision 20622)
+++ runtime/vm/assembler_arm.cc	(working copy)
@@ -1296,6 +1296,45 @@
 }
 
 
+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;
+  ldrh(result, FieldAddress(object, class_id_offset));
+}
+
+
+void Assembler::LoadClassById(Register result, Register class_id) {
+  ASSERT(result != class_id);
+  ldr(result, FieldAddress(CTX, Context::isolate_offset()));
+  const intptr_t table_offset_in_isolate =
+      Isolate::class_table_offset() + ClassTable::table_offset();
+  ldr(result, Address(result, table_offset_in_isolate));
+  ldr(result, Address(result, class_id, LSL, 2));
+}
+
+
+void Assembler::LoadClass(Register result, Register object, Register scratch) {
+  ASSERT(scratch != result);
+  LoadClassId(scratch, object);
+
+  ldr(result, FieldAddress(CTX, Context::isolate_offset()));
+  const intptr_t table_offset_in_isolate =
+      Isolate::class_table_offset() + ClassTable::table_offset();
+  ldr(result, Address(result, table_offset_in_isolate));
+  ldr(result, Address(result, scratch, LSL, 2));
+}
+
+
+void Assembler::CompareClassId(Register object,
+                               intptr_t class_id,
+                               Register scratch) {
+  LoadClassId(scratch, object);
+  CompareImmediate(scratch, class_id);
+}
+
+
 void Assembler::Bind(Label* label) {
   ASSERT(!label->IsBound());
   int bound_pc = buffer_.Size();