Implement IsNullCheck for CheckClassInstr. If input is nullable expected type, then check for null …

runtime/vm/intermediate_language_ia32.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_IA32.
 #if defined(TARGET_ARCH_IA32)
 
 #include "vm/intermediate_language.h"
 
 #include "vm/dart_entry.h"
@@ skipping 4035 matching lines @@
   comparison()->EmitBranchCode(compiler, this);
 }
 
 
 LocationSummary* CheckClassInstr::MakeLocationSummary() const {
   const intptr_t kNumInputs = 1;
   const intptr_t kNumTemps = 0;
   LocationSummary* summary =
       new LocationSummary(kNumInputs, kNumTemps, LocationSummary::kNoCall);
   summary->set_in(0, Location::RequiresRegister());
-  if (!null_check()) {
+  if (!IsNullCheck()) {
     summary->AddTemp(Location::RequiresRegister());
   }
   return summary;
 }
 
 
 void CheckClassInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
-  if (null_check()) {
+  if (IsNullCheck()) {
     Label* deopt = compiler->AddDeoptStub(deopt_id(),
                                           kDeoptCheckClass);
     const Immediate& raw_null =
         Immediate(reinterpret_cast<intptr_t>(Object::null()));
     __ cmpl(locs()->in(0).reg(), raw_null);

[Vyacheslav Egorov (Google), 2013/08/08 13:01:06]

Did you try to emit a testl() for nullable smis instead of comparison with null?
(shorter code)

[srdjan, 2013/08/08 14:15:40]

We never emit CheckClassInstr for nullable Smi-s (using CheckSmi instead). Had
an assert, but it seems to have been lost. I will add it.

     __ j(EQUAL, deopt);
     return;
   }
 
   ASSERT((unary_checks().GetReceiverClassIdAt(0) != kSmiCid) ||
          (unary_checks().NumberOfChecks() > 1));
   Register value = locs()->in(0).reg();
   Register temp = locs()->temp(0).reg();
   Label* deopt = compiler->AddDeoptStub(deopt_id(),
                                         kDeoptCheckClass);
@@ skipping 871 matching lines @@
                          PcDescriptors::kOther,
                          locs());
   __ Drop(2);  // Discard type arguments and receiver.
 }
 
 }  // namespace dart
 
 #undef __
 
 #endif  // defined TARGET_ARCH_IA32