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

runtime/vm/assembler_arm.cc

Index: runtime/vm/assembler_arm.cc
===================================================================
--- runtime/vm/assembler_arm.cc	(revision 36956)
+++ runtime/vm/assembler_arm.cc	(working copy)
@@ -1685,6 +1685,19 @@
 }
 
 
+void Assembler::LoadTaggedClassIdMayBeSmi(Register result, Register object) {

[zra, 2014/06/04 18:55:00]

tst(object, Operand(kSmiTagMask));
LoadImmediate(result, Smi::RawValue(kSmiCid), EQ);
LoadClassId(result, object, NE);
SmiTag(result, NE);

[srdjan, 2014/06/04 20:08:04]

Done and added condition to LoadClassId

+  Label load, done;
+  tst(object, Operand(kSmiTagMask));
+  b(&load, NE);
+  LoadImmediate(result, Smi::RawValue(kSmiCid));
+  b(&done);
+  Bind(&load);
+  LoadClassId(result, object);
+  SmiTag(result);
+  Bind(&done);
+}
+
+
 static bool CanEncodeBranchOffset(int32_t offset) {
   ASSERT(Utils::IsAligned(offset, 4));
   return Utils::IsInt(Utils::CountOneBits(kBranchOffsetMask), offset);