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

runtime/vm/intermediate_language.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/intermediate_language.h"
 
 #include "vm/bigint_operations.h"
 #include "vm/bit_vector.h"
 #include "vm/dart_entry.h"
 #include "vm/flow_graph_allocator.h"
@@ skipping 68 matching lines @@
 
 
 bool Value::Equals(Value* other) const {
   return definition() == other->definition();
 }
 
 
 CheckClassInstr::CheckClassInstr(Value* value,
                                  intptr_t deopt_id,
                                  const ICData& unary_checks)
-    : unary_checks_(unary_checks),
-      null_check_(false) {
+    : unary_checks_(unary_checks) {
   ASSERT(unary_checks.IsZoneHandle());
   // Expected useful check data.
   ASSERT(!unary_checks_.IsNull());
   ASSERT(unary_checks_.NumberOfChecks() > 0);
   ASSERT(unary_checks_.num_args_tested() == 1);
   SetInputAt(0, value);
   deopt_id_ = deopt_id;
   // Otherwise use CheckSmiInstr.
   ASSERT((unary_checks_.NumberOfChecks() != 1) ||
          (unary_checks_.GetReceiverClassIdAt(0) != kSmiCid));
@@ skipping 20 matching lines @@
 
 EffectSet CheckClassInstr::Dependencies() const {
   // Externalization of strings via the API can change the class-id.
   const bool externalizable =
       unary_checks().HasReceiverClassId(kOneByteStringCid) ||
       unary_checks().HasReceiverClassId(kTwoByteStringCid);
   return externalizable ? EffectSet::Externalization() : EffectSet::None();
 }
 
 
+bool CheckClassInstr::IsNullCheck() const {
+  if (unary_checks().NumberOfChecks() != 1) {
+    return false;
+  }
+  CompileType* in_type = value()->Type();
+  const intptr_t cid = unary_checks().GetCidAt(0);
+  return in_type->is_nullable() && (in_type->ToNullableCid() == cid);
+}
+
+
 bool GuardFieldInstr::AttributesEqual(Instruction* other) const {
   return field().raw() == other->AsGuardField()->field().raw();
 }
 
 
 bool AssertAssignableInstr::AttributesEqual(Instruction* other) const {
   AssertAssignableInstr* other_assert = other->AsAssertAssignable();
   ASSERT(other_assert != NULL);
   // This predicate has to be commutative for DominatorBasedCSE to work.
   // TODO(fschneider): Eliminate more asserts with subtype relation.
@@ skipping 2467 matching lines @@
     default:
       UNREACHABLE();
   }
   return kPowRuntimeEntry;
 }
 
 
 #undef __
 
 }  // namespace dart