VM: Improve polymorphic check-class in optimized code.

runtime/vm/flow_graph_compiler.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"  // Needed here to get TARGET_ARCH_XXX.
 
 #include "vm/flow_graph_compiler.h"
 
 #include "vm/bit_vector.h"
 #include "vm/cha.h"
@@ skipping 1464 matching lines @@
 
 static int HighestCountFirst(const CidTarget* a, const CidTarget* b) {
   // Negative if 'a' should sort before 'b'.
   return b->count - a->count;
 }
 
 
 // Returns 'sorted' array in decreasing count order.
 // The expected number of elements to sort is less than 10.
 void FlowGraphCompiler::SortICDataByCount(const ICData& ic_data,
-                                          GrowableArray<CidTarget>* sorted) {
+                                          GrowableArray<CidTarget>* sorted,
+                                          bool drop_smi) {
   ASSERT(ic_data.NumArgsTested() == 1);
   const intptr_t len = ic_data.NumberOfChecks();
   sorted->Clear();
 
   for (int i = 0; i < len; i++) {
-    sorted->Add(CidTarget(ic_data.GetReceiverClassIdAt(i),
+    intptr_t receiver_cid = ic_data.GetReceiverClassIdAt(i);
+    if (drop_smi && (receiver_cid == kSmiCid)) continue;
+    sorted->Add(CidTarget(receiver_cid,
                           &Function::ZoneHandle(ic_data.GetTargetAt(i)),
                           ic_data.GetCountAt(i)));
   }
   sorted->Sort(HighestCountFirst);
 }
 
 
 const ICData* FlowGraphCompiler::GetOrAddInstanceCallICData(
     intptr_t deopt_id,
     const String& target_name,
@@ skipping 69 matching lines @@
     case kUnboxedMint:
       return mint_class();
     default:
       UNREACHABLE();
       return Class::ZoneHandle();
   }
 }
 
 
 }  // namespace dart