Trace through const objects instead of spying on flow graph construction to find closure functions.…

runtime/vm/precompiler.cc

 // Copyright (c) 2015, 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/precompiler.h"
 
 #include "vm/code_patcher.h"
 #include "vm/compiler.h"
 #include "vm/isolate.h"
 #include "vm/log.h"
@@ skipping 42 matching lines @@
     isolate_(thread->isolate()),
     reset_fields_(reset_fields),
     changed_(false),
     function_count_(0),
     class_count_(0),
     selector_count_(0),
     dropped_function_count_(0),
     libraries_(GrowableObjectArray::Handle(Z, I->object_store()->libraries())),
     pending_functions_(
         GrowableObjectArray::Handle(Z, GrowableObjectArray::New())),
-    collected_closures_(
-        GrowableObjectArray::Handle(Z, GrowableObjectArray::New())),
     sent_selectors_(),
+    enqueued_functions_(),
     error_(Error::Handle(Z)) {
-  I->set_collected_closures(collected_closures_);
 }
 
 
 void Precompiler::DoCompileAll(
     Dart_QualifiedFunctionName embedder_entry_points[]) {
-  // Drop all existing code so we can use the presence of code as an indicator
-  // that we have already looked for the function's callees.
   ClearAllCode();
 
   // Make sure class hierarchy is stable before compilation so that CHA
-  // can be used.
+  // can be used. Also ensures lookup of entry points won't miss functions
+  // because their class hasn't been finalized yet.
   FinalizeAllClasses();
 
   // Start with the allocations and invocations that happen from C++.
   AddRoots(embedder_entry_points);
 
-  // TODO(rmacnak): Eagerly add field-invocation functions to all signature
-  // classes so closure calls don't go through the runtime.
-
   // Compile newly found targets and add their callees until we reach a fixed
   // point.
   Iterate();
 
-  CleanUp();
+  DropUncompiledFunctions();
+
+  // TODO(rmacnak): DropEmptyClasses();
+
+  BindStaticCalls();
+
+  DedupStackmaps();
 
   if (FLAG_trace_precompiler) {
     THR_Print("Precompiled %" Pd " functions, %" Pd " dynamic types,"
               " %" Pd " dynamic selectors.\n Dropped %" Pd " functions.\n",
               function_count_,
               class_count_,
               selector_count_,
               dropped_function_count_);
   }
 
@@ skipping 82 matching lines @@
   };
 
   Class& cls = Class::Handle(Z);
   for (intptr_t i = 0; kExternallyAllocatedCids[i] != kIllegalCid; i++) {
     cls = isolate()->class_table()->At(kExternallyAllocatedCids[i]);
     AddClass(cls);
   }
 
   Dart_QualifiedFunctionName vm_entry_points[] = {
     { "dart:async", "::", "_setScheduleImmediateClosure" },
+    { "dart:core", "::", "_completeDeferredLoads"},
     { "dart:core", "AbstractClassInstantiationError",
                    "AbstractClassInstantiationError._create" },
     { "dart:core", "ArgumentError", "ArgumentError." },
     { "dart:core", "AssertionError", "AssertionError." },
     { "dart:core", "CyclicInitializationError",
                    "CyclicInitializationError." },
     { "dart:core", "FallThroughError", "FallThroughError._create" },
     { "dart:core", "FormatException", "FormatException." },
     { "dart:core", "NoSuchMethodError", "NoSuchMethodError._withType" },
     { "dart:core", "NullThrownError", "NullThrownError." },
@@ skipping 86 matching lines @@
 
   while (changed_) {
     changed_ = false;
 
     while (pending_functions_.Length() > 0) {
       function ^= pending_functions_.RemoveLast();
       ProcessFunction(function);
     }
 
     CheckForNewDynamicFunctions();
-
-    // Drain collected_closures last because additions to this list come from
-    // outside the Precompiler and so do not flip our changed_ flag.
-    while (collected_closures_.Length() > 0) {
-      function ^= collected_closures_.RemoveLast();
-      ProcessFunction(function);
-    }
   }
 }
 
 
-void Precompiler::CleanUp() {
-  I->set_collected_closures(GrowableObjectArray::Handle(Z));
-
-  DropUncompiledFunctions();
-
-  // TODO(rmacnak): DropEmptyClasses();
-
-  BindStaticCalls();
-
-  DedupStackmaps();
-}
-
-
 void Precompiler::ProcessFunction(const Function& function) {
   if (!function.HasCode()) {
     function_count_++;
 
     if (FLAG_trace_precompiler) {
       THR_Print("Precompiling %" Pd " %s (%" Pd ", %s)\n",
                 function_count_,
                 function.ToLibNamePrefixedQualifiedCString(),
                 function.token_pos(),
                 Function::KindToCString(function.kind()));
@@ skipping 31 matching lines @@
 
 #if defined(TARGET_ARCH_IA32)
   FATAL("Callee scanning unimplemented for IA32");
 #endif
 
   const ObjectPool& pool = ObjectPool::Handle(Z, code.GetObjectPool());
   ICData& call_site = ICData::Handle(Z);
   String& selector = String::Handle(Z);
   Field& field = Field::Handle(Z);
   Class& cls = Class::Handle(Z);
+  Instance& instance = Instance::Handle(Z);
+  Code& target_code = Code::Handle(Z);
   for (intptr_t i = 0; i < pool.Length(); i++) {
     if (pool.InfoAt(i) == ObjectPool::kTaggedObject) {
       entry = pool.ObjectAt(i);
       if (entry.IsICData()) {
         call_site ^= entry.raw();
         if (call_site.NumberOfChecks() == 1) {
           // Probably a static call.
           target = call_site.GetTargetAt(0);
           AddFunction(target);
           if (!target.is_static()) {
             // Super call (should not enqueue selector) or dynamic call with a
             // CHA prediction (should enqueue selector).
             selector = call_site.target_name();
             AddSelector(selector);
           }
         } else {
           // A dynamic call.
           selector = call_site.target_name();
           AddSelector(selector);
           if (selector.raw() == Symbols::Call().raw()) {
             // Potential closure call.
             AddClosureCall(call_site);
           }
         }
       } else if (entry.IsField()) {
         // Potential need for field initializer.
         field ^= entry.raw();
         AddField(field);
       } else if (entry.IsInstance()) {
-        // Potential const object.
-        cls = entry.clazz();
-        AddClass(cls);
+        // Const object, literal or args descriptor.
+        instance ^= entry.raw();
+        AddConstObject(instance);
+      } else if (entry.IsFunction()) {
+        // Local closure function.
+        target ^= entry.raw();
+        AddFunction(target);
+      } else if (entry.IsCode()) {
+        target_code ^= entry.raw();
+        if (target_code.IsAllocationStubCode()) {
+          cls ^= target_code.owner();
+          AddClass(cls);
+        }
       }
     }
   }
 }
 
 
+void Precompiler::AddConstObject(const Instance& instance) {
+  const Class& cls = Class::Handle(Z, instance.clazz());
+  AddClass(cls);
+
+  if (instance.IsClosure()) {
+    // An implicit static closure.
+    const Function& func = Function::Handle(Z, Closure::function(instance));
+    ASSERT(func.is_static());
+    AddFunction(func);
+    return;
+  }
+
+  if (!instance.raw()->IsHeapObject()) return;

[srdjan, 2015/10/14 21:04:11]

Maybe more readable: if (instance.IsSmi()) return;

[rmacnak, 2015/10/14 22:22:41]

Done.

+  if (!instance.IsCanonical()) return;

[srdjan, 2015/10/14 21:04:11]

Add brief comment when that is the case.

[rmacnak, 2015/10/14 22:22:41]

Done.

+
+  class ConstObjectVisitor : public ObjectPointerVisitor {

[srdjan, 2015/10/14 21:04:11]

We typically add classes outside the scope of a function, but I do not care that
much.

+   public:
+    ConstObjectVisitor(Precompiler* precompiler, Isolate* isolate) :
+      ObjectPointerVisitor(isolate),
+      precompiler_(precompiler),
+      subinstance_(Object::Handle()) {}

[srdjan, 2015/10/14 21:04:11]

4 spaces indent.

[rmacnak, 2015/10/14 22:22:41]

Done.

+
+    virtual void VisitPointers(RawObject** first, RawObject** last) {
+      for (RawObject** current = first; current <= last; current++) {
+        subinstance_ = *current;
+        if (subinstance_.IsInstance()) {
+          precompiler_->AddConstObject(Instance::Cast(subinstance_));
+        }
+      }

[srdjan, 2015/10/14 21:04:11]

clear subinstance_ to null (so that it does not hold onto an object)?

[rmacnak, 2015/10/14 22:22:41]

Done.

+    }
+
+   private:
+    Precompiler* precompiler_;
+    Object& subinstance_;
+  };
+
+  ConstObjectVisitor visitor(this, I);
+  instance.raw()->VisitPointers(&visitor);
+}
+
+
 void Precompiler::AddClosureCall(const ICData& call_site) {
   const Array& arguments_descriptor =
       Array::Handle(Z, call_site.arguments_descriptor());
   const Type& function_impl =
       Type::Handle(Z, I->object_store()->function_impl_type());
   const Class& cache_class =
       Class::Handle(Z, function_impl.type_class());
   const Function& dispatcher = Function::Handle(Z,
       cache_class.GetInvocationDispatcher(Symbols::Call(),
                                           arguments_descriptor,
                                           RawFunction::kInvokeFieldDispatcher,
                                           true /* create_if_absent */));
   AddFunction(dispatcher);
 }
 
 
 void Precompiler::AddField(const Field& field) {
   if (field.is_static()) {
-    // Potential const object. Uninitialized field will harmlessly do a
-    // redundant add of the Null class.
     const Object& value = Object::Handle(Z, field.StaticValue());
-    const Class& cls = Class::Handle(Z, value.clazz());
-    AddClass(cls);
+    if (value.IsInstance()) {
+      AddConstObject(Instance::Cast(value));
+    }
 
     if (field.has_initializer()) {
       // Should not be in the middle of initialization while precompiling.
       ASSERT(value.raw() != Object::transition_sentinel().raw());
 
       const bool is_initialized = value.raw() != Object::sentinel().raw();
       if (is_initialized && !reset_fields_) return;
 
       if (field.HasPrecompiledInitializer()) return;
 
       if (FLAG_trace_precompiler) {
         THR_Print("Precompiling initializer for %s\n", field.ToCString());
       }
       ASSERT(!Dart::IsRunningPrecompiledCode());
       field.SetStaticValue(Instance::Handle(field.SavedInitialStaticValue()));
       Compiler::CompileStaticInitializer(field);
 
       const Function& function =
           Function::Handle(Z, field.PrecompiledInitializer());
       AddCalleesOf(function);
     }
   }
 }
 
 
 void Precompiler::AddFunction(const Function& function) {
-  if (function.HasCode()) return;
+  if (enqueued_functions_.Lookup(&function) != NULL) return;
 
+  enqueued_functions_.Insert(&Function::ZoneHandle(Z, function.raw()));
   pending_functions_.Add(function);
   changed_ = true;
 }
 
 
 bool Precompiler::IsSent(const String& selector) {
   if (selector.IsNull()) {
     return false;
   }
   return sent_selectors_.Lookup(&selector) != NULL;
@@ skipping 44 matching lines @@
   String& selector = String::Handle(Z);
   String& selector2 = String::Handle(Z);
   String& selector3 = String::Handle(Z);
 
   for (intptr_t i = 0; i < libraries_.Length(); i++) {
     lib ^= libraries_.At(i);
     ClassDictionaryIterator it(lib, ClassDictionaryIterator::kIteratePrivate);
     while (it.HasNext()) {
       cls = it.GetNextClass();
 
-      if (!cls.is_allocated()) {
-        bool has_compiled_constructor = false;
-        if (cls.allocation_stub() != Code::null()) {
-          // Regular objects.
-          has_compiled_constructor = true;
-        } else if (cls.is_synthesized_class()) {
-          // Enums.
-          has_compiled_constructor = true;
-        } else {
-          // Objects only allocated via const constructors, and not stored in a
-          // static field or code.
-          // E.g. A in
-          //   class A {
-          //     const A();
-          //     toString() => "Don't drop me!";
-          //   }
-          //   class B {
-          //     const a = const A();
-          //     const B();
-          //     static const theB = const B();
-          //   }
-          //   main() => print(B.theB.a);
-          functions = cls.functions();
-          for (intptr_t k = 0; k < functions.Length(); k++) {
-            function ^= functions.At(k);
-            if (function.IsGenerativeConstructor() &&
-                function.HasCode()) {
-              has_compiled_constructor = true;
-              break;
-            }
-          }
-        }
-        if (!has_compiled_constructor) {
-          continue;
-        }
-        AddClass(cls);
-      }
+      if (!cls.is_allocated()) continue;
 
       functions = cls.functions();
       for (intptr_t k = 0; k < functions.Length(); k++) {
         function ^= functions.At(k);
 
         if (function.is_static() || function.is_abstract()) continue;
 
         // Don't bail out early if there is already code because we may discover
         // the corresponding getter selector is sent in some later iteration.
         // if (function.HasCode()) continue;
@@ skipping 268 matching lines @@
         continue;  // class 'dynamic' is in the read-only VM isolate.
       }
       cls.EnsureIsFinalized(T);
     }
   }
   I->set_all_classes_finalized(true);
 }
 
 
 }  // namespace dart