Add --use_cha (default true, switch to false if you use dynamic class loading). Use CHA to specify …

runtime/vm/intermediate_language_x64.cc

 // Copyright (c) 2012, 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_X64.
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/intermediate_language.h"
 
 #include "lib/error.h"
@@ skipping 2173 matching lines @@
   const intptr_t kNumTemps = 1;
   LocationSummary* summary =
       new LocationSummary(kNumInputs, kNumTemps, LocationSummary::kNoCall);
   summary->set_in(0, Location::RequiresRegister());
   summary->set_temp(0, Location::RequiresRegister());
   return summary;
 }
 
 
 void CheckClassComp::EmitNativeCode(FlowGraphCompiler* compiler) {
+  const intptr_t v_cid = value()->ResultCid();
+  const intptr_t num_checks = ic_data()->NumberOfChecks();
+  if ((num_checks == 1) &&
+      (v_cid == ic_data()->GetReceiverClassIdAt(0))) {
+    // No checks needed.
+    // TODO(srdjan): Should the computation have been removed instead?
+    return;
+  }
   Register value = locs()->in(0).reg();
   Register temp = locs()->temp(0).reg();
   Label* deopt = compiler->AddDeoptStub(deopt_id(),
                                         try_index(),
                                         kDeoptCheckClass);
   ASSERT(ic_data()->GetReceiverClassIdAt(0) != kSmiCid);
   __ testq(value, Immediate(kSmiTagMask));
   __ j(ZERO, deopt);
   __ LoadClassId(temp, value);
   Label is_ok;
-  const intptr_t num_checks = ic_data()->NumberOfChecks();
   const bool use_near_jump = num_checks < 5;
   for (intptr_t i = 0; i < num_checks; i++) {
     __ cmpl(temp, Immediate(ic_data()->GetReceiverClassIdAt(i)));
     if (i == (num_checks - 1)) {
       __ j(NOT_EQUAL, deopt);
     } else {
       if (use_near_jump) {
         __ j(EQUAL, &is_ok, Assembler::kNearJump);
       } else {
         __ j(EQUAL, &is_ok);
       }
     }
   }
   __ Bind(&is_ok);
 }
 
 }  // namespace dart
 
 #undef __
 
 #endif  // defined TARGET_ARCH_X64