Apply optimization after class-id propagation: instance calls without ICData are optimized by using…

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/bit_vector.h"
 #include "vm/cha.h"
 #include "vm/flow_graph_builder.h"
 #include "vm/flow_graph_compiler.h"
 #include "vm/hash_map.h"
 #include "vm/il_printer.h"
 #include "vm/intermediate_language.h"
 #include "vm/object_store.h"
 #include "vm/parser.h"
+#include "vm/resolver.h"
 #include "vm/scopes.h"
 #include "vm/symbols.h"
 
 namespace dart {
 
 DECLARE_FLAG(bool, eliminate_type_checks);
 DECLARE_FLAG(bool, enable_type_checks);
 DEFINE_FLAG(bool, trace_optimization, false, "Print optimization details.");
 DECLARE_FLAG(bool, trace_type_check_elimination);
 DEFINE_FLAG(bool, use_cha, true, "Use class hierarchy analysis.");
 DEFINE_FLAG(bool, load_cse, true, "Use redundant load elimination.");
 DEFINE_FLAG(bool, trace_range_analysis, false, "Trace range analysis progress");
 DEFINE_FLAG(bool, trace_constant_propagation, false,
             "Print constant propagation and useless code elimination.");
 
+
 void FlowGraphOptimizer::ApplyICData() {
   VisitBlocks();
 }
 
 
+// Attempts to convert an instance call (IC call) using propagated class-ids,
+// e.g., receiver class id.
+void FlowGraphOptimizer::ApplyClassIds() {
+  ASSERT(current_iterator_ == NULL);
+  for (intptr_t i = 0; i < block_order_.length(); ++i) {
+    BlockEntryInstr* entry = block_order_[i];
+    ForwardInstructionIterator it(entry);
+    current_iterator_ = &it;
+    for (; !it.Done(); it.Advance()) {
+      if (it.Current()->IsInstanceCall()) {
+        InstanceCallInstr* call = it.Current()->AsInstanceCall();
+        if (call->HasICData()) {
+          if (TryCreateICData(call)) {
+            VisitInstanceCall(call);
+          }
+        }
+      }
+    }
+    current_iterator_ = NULL;
+  }
+}
+
+
+// Attempt to build ICData for call using propagated class-ids.
+bool FlowGraphOptimizer::TryCreateICData(InstanceCallInstr* call) {
+  ASSERT(call->HasICData());
+  if (call->ic_data()->NumberOfChecks() > 0) {
+    // This occurs when an instance call has too many checks.
+    // TODO(srdjan): Replace IC call with megamorphic call.
+    return false;
+  }
+  GrowableArray<intptr_t> class_ids(call->ic_data()->num_args_tested());
+  ASSERT(call->ic_data()->num_args_tested() <= call->ArgumentCount());
+  for (intptr_t i = 0; i < call->ic_data()->num_args_tested(); i++) {
+    intptr_t cid = call->ArgumentAt(i)->value()->ResultCid();
+    class_ids.Add(cid);
+  }
+  // TODO(srdjan): Test for other class_ids > 1.
+  if (class_ids.length() != 1) return false;
+  if (class_ids[0] != kDynamicCid) {
+    const intptr_t num_named_arguments = call->argument_names().IsNull() ?
+        0 : call->argument_names().Length();
+    const Class& receiver_class = Class::Handle(
+        Isolate::Current()->class_table()->At(class_ids[0]));
+    Function& function = Function::Handle();
+    function = Resolver::ResolveDynamicForReceiverClass(
+        receiver_class,
+        call->function_name(),
+        call->ArgumentCount(),
+        num_named_arguments);
+    if (function.IsNull()) {
+      return false;
+    }
+    // Create new ICData, do not modify the one attached to the instruction
+    // since it is attached to the assembly instruction itself.
+    // TODO(srdjan): Prevent modification of ICData object that is
+    // referenced in assembly code.
+    ICData& ic_data = ICData::ZoneHandle(ICData::New(
+        flow_graph_->parsed_function().function(),
+        call->function_name(),
+        call->deopt_id(),
+        class_ids.length()));
+    ic_data.AddReceiverCheck(class_ids[0], function);
+    call->set_ic_data(&ic_data);
+    return true;
+  }
+  return false;
+}
+
+
 static void ReplaceCurrentInstruction(ForwardInstructionIterator* it,
                                       Instruction* current,
                                       Instruction* replacement) {
   if ((replacement != NULL) && current->IsDefinition()) {
     Definition* current_defn = current->AsDefinition();
     Definition* replacement_defn = replacement->AsDefinition();
     ASSERT(replacement_defn != NULL);
     current_defn->ReplaceUsesWith(replacement_defn);
 
     if (FLAG_trace_optimization) {
@@ skipping 1060 matching lines @@
         call_with_checks = false;
       } else {
         call_with_checks = true;
       }
       PolymorphicInstanceCallInstr* call =
           new PolymorphicInstanceCallInstr(instr, unary_checks,
                                            call_with_checks);
       instr->ReplaceWith(call, current_iterator());
     }
   }
-  // An instance call without ICData should continue calling via IC calls
-  // which should trigger reoptimization of optimized code.
+  // An instance call without ICData will trigger deoptimization.
 }
 
 
 void FlowGraphOptimizer::VisitStaticCall(StaticCallInstr* call) {
   MethodRecognizer::Kind recognized_kind =
       MethodRecognizer::RecognizeKind(call->function());
   if (recognized_kind == MethodRecognizer::kMathSqrt) {
     MathSqrtInstr* sqrt = new MathSqrtInstr(call->ArgumentAt(0)->value(), call);
     call->ReplaceWith(sqrt, current_iterator());
     RemovePushArguments(call);
@@ skipping 2264 matching lines @@
 
   if (FLAG_trace_constant_propagation) {
     OS::Print("\n==== After constant propagation ====\n");
     FlowGraphPrinter printer(*graph_);
     printer.PrintBlocks();
   }
 }
 
 
 }  // namespace dart