Prefer single CID test for 'is' operator

runtime/vm/jit_optimizer.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.
 #ifndef DART_PRECOMPILED_RUNTIME
 #include "vm/jit_optimizer.h"
 
 #include "vm/bit_vector.h"
 #include "vm/branch_optimizer.h"
 #include "vm/cha.h"
 #include "vm/compiler.h"
@@ skipping 1295 matching lines @@
   if (call->ArgumentCount() == 2) {
     instantiator_type_args = flow_graph()->constant_null();
     function_type_args = flow_graph()->constant_null();
     ASSERT(call->MatchesCoreName(Symbols::_simpleInstanceOf()));
     type = AbstractType::Cast(call->ArgumentAt(1)->AsConstant()->value()).raw();
   } else {
     instantiator_type_args = call->ArgumentAt(1);
     function_type_args = call->ArgumentAt(2);
     type = AbstractType::Cast(call->ArgumentAt(3)->AsConstant()->value()).raw();
   }
+
+  if (TypeCheckAsClassEquality(type)) {
+    LoadClassIdInstr* left_cid = new (Z) LoadClassIdInstr(new (Z) Value(left));
+    InsertBefore(call, left_cid, NULL, FlowGraph::kValue);
+    const intptr_t type_cid = Class::Handle(Z, type.type_class()).id();
+    ConstantInstr* cid =
+        flow_graph()->GetConstant(Smi::Handle(Z, Smi::New(type_cid)));
+
+    StrictCompareInstr* check_cid = new (Z) StrictCompareInstr(
+        call->token_pos(), Token::kEQ_STRICT, new (Z) Value(left_cid),
+        new (Z) Value(cid), /* number_check = */ false, Thread::kNoDeoptId);
+    ReplaceCall(call, check_cid);
+    return;
+  }
+
   const ICData& unary_checks =
       ICData::ZoneHandle(Z, call->ic_data()->AsUnaryClassChecks());
   const intptr_t number_of_checks = unary_checks.NumberOfChecks();
   if ((number_of_checks > 0) &&
       (number_of_checks <= FLAG_max_polymorphic_checks)) {
     ZoneGrowableArray<intptr_t>* results =
         new (Z) ZoneGrowableArray<intptr_t>(number_of_checks * 2);
     Bool& as_bool =
         Bool::ZoneHandle(Z, InstanceOfAsBool(unary_checks, type, results));
     if (as_bool.IsNull()) {
@@ skipping 16 matching lines @@
         push->ReplaceUsesWith(push->value()->definition());
         push->RemoveFromGraph();
       }
       call->ReplaceUsesWith(bool_const);
       ASSERT(current_iterator()->Current() == call);
       current_iterator()->RemoveCurrentFromGraph();
       return;
     }
   }
 
-  if (TypeCheckAsClassEquality(type)) {
-    LoadClassIdInstr* left_cid = new (Z) LoadClassIdInstr(new (Z) Value(left));
-    InsertBefore(call, left_cid, NULL, FlowGraph::kValue);
-    const intptr_t type_cid = Class::Handle(Z, type.type_class()).id();
-    ConstantInstr* cid =
-        flow_graph()->GetConstant(Smi::Handle(Z, Smi::New(type_cid)));
-
-    StrictCompareInstr* check_cid = new (Z) StrictCompareInstr(
-        call->token_pos(), Token::kEQ_STRICT, new (Z) Value(left_cid),
-        new (Z) Value(cid), /* number_check = */ false, Thread::kNoDeoptId);
-    ReplaceCall(call, check_cid);
-    return;
-  }
-
   InstanceOfInstr* instance_of = new (Z) InstanceOfInstr(
       call->token_pos(), new (Z) Value(left),
       new (Z) Value(instantiator_type_args), new (Z) Value(function_type_args),
       type, call->deopt_id());
   ReplaceCall(call, instance_of);
 }
 
 
 // TODO(srdjan): Apply optimizations as in ReplaceWithInstanceOf (TestCids).
 void JitOptimizer::ReplaceWithTypeCast(InstanceCallInstr* call) {
@@ skipping 395 matching lines @@
   // Discard the environment from the original instruction because the store
   // can't deoptimize.
   instr->RemoveEnvironment();
   ReplaceCall(instr, store);
   return true;
 }
 
 
 }  // namespace dart
 #endif  // DART_PRECOMPILED_RUNTIME