Fix performance regression introduced by new equality semantic: we do not collect ICData when compa…

runtime/vm/flow_graph_optimizer.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/flow_graph_optimizer.h"
 
 #include "vm/flow_graph_builder.h"
 #include "vm/hash_map.h"
 #include "vm/il_printer.h"
 #include "vm/object_store.h"
@@ skipping 583 matching lines @@
   } else if (HasOnlyTwoDouble(ic_data)) {
     comp->set_operands_class_id(kDoubleCid);
   } else if (comp->ic_data()->AllReceiversAreNumbers()) {
     comp->set_operands_class_id(kNumberCid);
   }
 }
 
 
 void FlowGraphOptimizer::VisitEqualityCompare(EqualityCompareComp* comp,
                                               BindInstr* instr) {
+  // If one of the inputs is null, no ICdata will be collected.
+  if (comp->left()->BindsToConstantNull() ||
+      comp->right()->BindsToConstantNull()) {
+    Token::Kind strict_kind = (comp->kind() == Token::kEQ) ?
+        Token::kEQ_STRICT : Token::kNE_STRICT;
+    StrictCompareComp* strict_comp =
+        new StrictCompareComp(strict_kind, comp->left(), comp->right());
+    instr->set_computation(strict_comp);
+    return;
+  }
   if (!comp->HasICData() || (comp->ic_data()->NumberOfChecks() == 0)) return;
   if (comp->ic_data()->NumberOfChecks() == 1) {
     ASSERT(comp->ic_data()->num_args_tested() == 2);
     GrowableArray<intptr_t> class_ids;
     Function& target = Function::Handle();
     comp->ic_data()->GetCheckAt(0, &class_ids, &target);
     // TODO(srdjan): allow for mixed mode comparison.
     if ((class_ids[0] == kSmiCid) && (class_ids[1] == kSmiCid)) {
       comp->set_receiver_class_id(kSmiCid);
     } else if ((class_ids[0] == kDoubleCid) && (class_ids[1] == kDoubleCid)) {
       comp->set_receiver_class_id(kDoubleCid);
     } else {
       ASSERT(comp->receiver_class_id() == kIllegalCid);
     }
   } else if (comp->ic_data()->AllReceiversAreNumbers()) {
     comp->set_receiver_class_id(kNumberCid);
   }
 }
 
 
+void FlowGraphOptimizer::VisitBranch(BranchInstr* instr) {
+  if ((instr->kind() != Token::kEQ) &&
+      (instr->kind() != Token::kNE)) {
+    return;
+  }
+  if (!instr->left()->BindsToConstantNull() &&
+      !instr->right()->BindsToConstantNull()) {
+    return;
+  }
+  Token::Kind strict_kind = (instr->kind() == Token::kEQ) ?
+      Token::kEQ_STRICT : Token::kNE_STRICT;
+  instr->set_kind(strict_kind);
+}
+
+
 void FlowGraphOptimizer::VisitBind(BindInstr* instr) {
   instr->computation()->Accept(this, instr);
 }
 
 
 void FlowGraphTypePropagator::VisitAssertAssignable(AssertAssignableComp* comp,
                                                     BindInstr* instr) {
   if (FLAG_eliminate_type_checks &&
       !comp->is_eliminated() &&
       comp->value()->CompileTypeIsMoreSpecificThan(comp->dst_type())) {
@@ skipping 282 matching lines @@
         OS::Print("Replacing v%d with v%d\n",
                   instr->ssa_temp_index(),
                   result->ssa_temp_index());
       }
     }
   }
 }
 
 
 }  // namespace dart