Cache lookups at megamorphic call sites in optimized code.

runtime/vm/code_generator.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/code_generator.h"
 
 #include "vm/assembler_macros.h"
 #include "vm/ast.h"
 #include "vm/bigint_operations.h"
 #include "vm/code_patcher.h"
@@ skipping 1007 matching lines @@
   GrowableArray<const Instance*> args(3);
   args.Add(&receiver);
   args.Add(&arg1);
   args.Add(&arg2);
   const Function& result =
       Function::Handle(InlineCacheMissHandler(args, ic_data, arg_descriptor));
   arguments.SetReturn(result);
 }
 
 
+// Handle a miss of a megamorphic cache.
+//   Arg0: Receiver.
+//   Arg1: ICData object.
+//   Arg2: Arguments descriptor array.
+
+//   Returns: target instructions to call or null if the
+// InstanceFunctionLookup stub should be used (e.g., to invoke no such
+// method and implicit closures)..
+DEFINE_RUNTIME_ENTRY(MegamorphicCacheMissHandler, 3) {
+  ASSERT(arguments.ArgCount() ==
+     kMegamorphicCacheMissHandlerRuntimeEntry.argument_count());
+  const Instance& receiver = Instance::CheckedHandle(arguments.ArgAt(0));
+  const ICData& ic_data = ICData::CheckedHandle(arguments.ArgAt(1));
+  const Array& descriptor = Array::CheckedHandle(arguments.ArgAt(2));
+  const String& name = String::Handle(ic_data.target_name());
+  const MegamorphicCache& cache = MegamorphicCache::Handle(
+      isolate->megamorphic_cache_table()->Lookup(name, descriptor));
+  Class& cls = Class::Handle(receiver.clazz());
+  // For lookups treat null as an instance of class Object.
+  if (cls.IsNullClass()) {
+    cls = isolate->object_store()->object_class();
+  }
+  ASSERT(!cls.IsNull());
+  if (FLAG_trace_ic || FLAG_trace_ic_miss_in_optimized) {
+    OS::Print("Megamorphic IC miss, class=%s, function=%s\n",
+              cls.ToCString(), name.ToCString());
+  }
+
+  intptr_t arg_count =
+      Smi::Cast(Object::Handle(descriptor.At(0))).Value();
+  intptr_t named_arg_count =
+      arg_count - Smi::Cast(Object::Handle(descriptor.At(1))).Value();
+  const Function& target = Function::Handle(
+      Resolver::ResolveDynamicForReceiverClass(cls,
+                                               name,
+                                               arg_count,
+                                               named_arg_count));
+
+  Instructions& instructions = Instructions::Handle();
+  if (!target.IsNull()) {
+    if (!target.HasCode()) {
+      const Error& error =
+          Error::Handle(Compiler::CompileFunction(target));
+      if (!error.IsNull()) Exceptions::PropagateError(error);
+    }
+    ASSERT(target.HasCode());
+    instructions = Code::Handle(target.CurrentCode()).instructions();
+  }
+  arguments.SetReturn(instructions);
+  if (instructions.IsNull()) return;
+
+  cache.EnsureCapacity();
+  const Smi& class_id = Smi::Handle(Smi::New(cls.id()));
+  cache.Insert(class_id, target);
+  return;
+}
+
+
 // Updates IC data for two arguments. Used by the equality operation when
 // the control flow bypasses regular inline cache (null arguments).
 //   Arg0: Receiver object.
 //   Arg1: Argument after receiver.
 //   Arg2: Target's name.
 //   Arg3: ICData.
 DEFINE_RUNTIME_ENTRY(UpdateICDataTwoArgs, 4) {
   ASSERT(arguments.ArgCount() ==
       kUpdateICDataTwoArgsRuntimeEntry.argument_count());
   const Instance& receiver = Instance::CheckedHandle(arguments.ArgAt(0));
@@ skipping 855 matching lines @@
   Isolate* isolate = Isolate::Current();
   StackZone zone(isolate);
   HANDLESCOPE(isolate);
   const Bigint& big_left = Bigint::Handle(left);
   const Bigint& big_right = Bigint::Handle(right);
   return BigintOperations::Compare(big_left, big_right);
 }
 END_LEAF_RUNTIME_ENTRY
 
 }  // namespace dart