Specialize instance calls when the call receiver is the method receiver and the method class has a …

runtime/vm/aot_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.
 
 #include "vm/aot_optimizer.h"
 
 #include "vm/bit_vector.h"
 #include "vm/branch_optimizer.h"
 #include "vm/cha.h"
 #include "vm/compiler.h"
@@ skipping 11 matching lines @@
 #include "vm/object_store.h"
 #include "vm/parser.h"
 #include "vm/precompiler.h"
 #include "vm/resolver.h"
 #include "vm/scopes.h"
 #include "vm/stack_frame.h"
 #include "vm/symbols.h"
 
 namespace dart {
 
+DEFINE_FLAG(int, max_exhaustive_polymorphic_checks, 5,
+            "If a call receiver is known to be of at most this many classes, "
+            "generate exhaustive class tests instead of a megamorphic call");
+
 // Quick access to the current isolate and zone.
 #define I (isolate())
 #define Z (zone())
 
 static bool ShouldInlineSimd() {
   return FlowGraphCompiler::SupportsUnboxedSimd128();
 }
 
 
 static bool CanUnboxDouble() {
@@ skipping 232 matching lines @@
   if (receiver_cid == kDynamicCid) {
     return;  // No information about receiver was infered.
   }
 
   const ICData& ic_data = TrySpecializeICData(call->ic_data(), receiver_cid);
   if (ic_data.raw() == call->ic_data().raw()) {
     // No specialization.
     return;
   }
 
-  const bool with_checks = false;
   PolymorphicInstanceCallInstr* specialized =
       new(Z) PolymorphicInstanceCallInstr(call->instance_call(),
                                           ic_data,
-                                          with_checks);
+                                          /* with_checks = */ false,
+                                          /* complete = */ false);
   call->ReplaceWith(specialized, current_iterator());
 }
 
 
 static BinarySmiOpInstr* AsSmiShiftLeftInstruction(Definition* d) {
   BinarySmiOpInstr* instr = d->AsBinarySmiOp();
   if ((instr != NULL) && (instr->op_kind() == Token::kSHL)) {
     return instr;
   }
   return NULL;
@@ skipping 2135 matching lines @@
     has_one_target = !polymorphic_target;
   }
 
   if (has_one_target) {
     RawFunction::Kind function_kind =
         Function::Handle(Z, unary_checks.GetTargetAt(0)).kind();
     if (!flow_graph()->InstanceCallNeedsClassCheck(
             instr, function_kind)) {
       PolymorphicInstanceCallInstr* call =
           new(Z) PolymorphicInstanceCallInstr(instr, unary_checks,
-                                              /* with_checks = */ false);
+                                              /* with_checks = */ false,
+                                              /* complete = */ true);
       instr->ReplaceWith(call, current_iterator());
       return;
     }
   }
   switch (instr->token_kind()) {
     case Token::kEQ:
     case Token::kLT:
     case Token::kLTE:
     case Token::kGT:
     case Token::kGTE:
@@ skipping 52 matching lines @@
         // Create fake IC data with the resolved target.
         const ICData& ic_data = ICData::Handle(
             ICData::New(flow_graph_->function(),
                         instr->function_name(),
                         args_desc_array,
                         Thread::kNoDeoptId,
                         /* args_tested = */ 1));
         ic_data.AddReceiverCheck(receiver_class.id(), function);
         PolymorphicInstanceCallInstr* call =
             new(Z) PolymorphicInstanceCallInstr(instr, ic_data,
-                                                /* with_checks = */ false);
+                                                /* with_checks = */ false,
+                                                /* complete = */ true);
         instr->ReplaceWith(call, current_iterator());
         return;
       }
     }
   }
 
+  Definition* callee_receiver = instr->ArgumentAt(0);
+  const Function& function = flow_graph_->function();
+  if (function.IsDynamicFunction() &&
+      flow_graph_->IsReceiver(callee_receiver)) {
+    // Call receiver is method receiver.
+    Class& receiver_class = Class::Handle(Z, function.Owner());
+    GrowableArray<intptr_t> class_ids(6);
+    if (thread()->cha()->ConcreteSubclasses(receiver_class, &class_ids)) {
+      if (class_ids.length() <= FLAG_max_exhaustive_polymorphic_checks) {
+        if (FLAG_trace_cha) {
+          THR_Print("  **(CHA) Only %" Pd " concrete subclasses of %s for %s\n",
+                    class_ids.length(),
+                    receiver_class.ToCString(),
+                    instr->function_name().ToCString());
+        }
+
+        const Array& args_desc_array = Array::Handle(Z,
+            ArgumentsDescriptor::New(instr->ArgumentCount(),
+                                     instr->argument_names()));
+        ArgumentsDescriptor args_desc(args_desc_array);
+
+        const ICData& ic_data = ICData::Handle(
+            ICData::New(function,
+                        instr->function_name(),
+                        args_desc_array,
+                        Thread::kNoDeoptId,
+                        /* args_tested = */ 1));
+
+        Function& target = Function::Handle(Z);
+        Class& cls = Class::Handle(Z);
+        bool includes_dispatcher_case = false;
+        for (intptr_t i = 0; i < class_ids.length(); i++) {
+          intptr_t cid = class_ids[i];
+          cls = isolate()->class_table()->At(cid);
+          target = Resolver::ResolveDynamicForReceiverClass(
+              cls,
+              instr->function_name(),
+              args_desc);
+          if (target.IsNull()) {
+            // noSuchMethod, call through getter or closurization
+            includes_dispatcher_case = true;
+          } else {
+            ic_data.AddReceiverCheck(cid, target);
+          }
+        }
+        if (!includes_dispatcher_case && (ic_data.NumberOfChecks() > 0)) {
+          PolymorphicInstanceCallInstr* call =
+              new(Z) PolymorphicInstanceCallInstr(instr, ic_data,
+                                                  /* with_checks = */ true,
+                                                  /* complete = */ true);
+          instr->ReplaceWith(call, current_iterator());
+          return;
+        }
+      }
+    }
+  }
+
   // More than one targets. Generate generic polymorphic call without
   // deoptimization.
   if (instr->ic_data()->NumberOfUsedChecks() > 0) {
     ASSERT(!FLAG_polymorphic_with_deopt);
     // OK to use checks with PolymorphicInstanceCallInstr since no
     // deoptimization is allowed.
     PolymorphicInstanceCallInstr* call =
         new(Z) PolymorphicInstanceCallInstr(instr, unary_checks,
-                                            /* with_checks = */ true);
+                                            /* with_checks = */ true,
+                                            /* complete = */ false);
     instr->ReplaceWith(call, current_iterator());
     return;
   }
 }
 
 
 void AotOptimizer::VisitStaticCall(StaticCallInstr* call) {
   if (!CanUnboxDouble()) {
     return;
   }
@@ skipping 214 matching lines @@
 
   // Discard the environment from the original instruction because the store
   // can't deoptimize.
   instr->RemoveEnvironment();
   ReplaceCall(instr, store);
   return true;
 }
 
 
 }  // namespace dart