Initial isolate reload support

runtime/vm/object_reload.cc

Index: runtime/vm/object_reload.cc
diff --git a/runtime/vm/object_reload.cc b/runtime/vm/object_reload.cc
new file mode 100644
index 0000000000000000000000000000000000000000..2cf57e48e9f88a0cf04b919959631d9fdb572491
--- /dev/null
+++ b/runtime/vm/object_reload.cc
@@ -0,0 +1,548 @@
+// Copyright (c) 2016, 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/object.h"
+
+#include "vm/isolate_reload.h"
+#include "vm/log.h"
+#include "vm/resolver.h"
+#include "vm/symbols.h"
+
+namespace dart {
+
+#ifndef PRODUCT
+
+DECLARE_FLAG(bool, trace_reload);
+DECLARE_FLAG(bool, two_args_smi_icd);
+
+#define IRC (Isolate::Current()->reload_context())
+
+class ObjectReloadUtils : public AllStatic {
+  static void DumpLibraryDictionary(const Library& lib) {
+    DictionaryIterator it(lib);
+    Object& entry = Object::Handle();
+    String& name = String::Handle();
+    TIR_Print("Dumping dictionary for %s\n", lib.ToCString());
+    while (it.HasNext()) {
+      entry = it.GetNext();
+      name = entry.DictionaryName();
+      TIR_Print("%s -> %s\n", name.ToCString(), entry.ToCString());
+    }
+  }
+};
+
+
+void Function::Reparent(const Class& new_cls) const {
+  set_owner(new_cls);
+}
+
+
+void Function::ZeroEdgeCounters() const {
+  const Array& saved_ic_data = Array::Handle(ic_data_array());
+  if (saved_ic_data.IsNull()) {
+    return;
+  }
+  const intptr_t saved_ic_datalength = saved_ic_data.Length();
+  ASSERT(saved_ic_datalength > 0);
+  const Array& edge_counters_array =
+      Array::Handle(Array::RawCast(saved_ic_data.At(0)));
+  ASSERT(!edge_counters_array.IsNull());
+  // Fill edge counters array with zeros.
+  const Smi& zero = Smi::Handle(Smi::New(0));
+  for (intptr_t i = 0; i < edge_counters_array.Length(); i++) {
+    edge_counters_array.SetAt(i, zero);
+  }
+}
+
+
+static void ClearICs(const Function& function, const Code& code) {
+  if (function.ic_data_array() == Array::null()) {
+    return;  // Already reset in an earlier round.
+  }
+
+  Thread* thread = Thread::Current();
+  Zone* zone = thread->zone();
+
+  ZoneGrowableArray<const ICData*>* ic_data_array =
+      new(zone) ZoneGrowableArray<const ICData*>();
+  function.RestoreICDataMap(ic_data_array, false /* clone ic-data */);
+  if (ic_data_array->length() == 0) {
+    return;
+  }
+  const PcDescriptors& descriptors =
+      PcDescriptors::Handle(code.pc_descriptors());
+  PcDescriptors::Iterator iter(descriptors, RawPcDescriptors::kIcCall |
+                                            RawPcDescriptors::kUnoptStaticCall);
+  while (iter.MoveNext()) {
+    const ICData* ic_data = (*ic_data_array)[iter.DeoptId()];
+    if (ic_data == NULL) {
+      continue;
+    }
+    bool is_static_call = iter.Kind() == RawPcDescriptors::kUnoptStaticCall;
+    ic_data->Reset(is_static_call);
+  }
+}
+
+
+void Function::FillICDataWithSentinels(const Code& code) const {
+  ASSERT(code.raw() == CurrentCode());
+  ClearICs(*this, code);
+}
+
+
+void Class::CopyStaticFieldValues(const Class& old_cls) const {
+  // We only update values for non-enum classes.
+  const bool update_values = !is_enum_class();
+
+  IsolateReloadContext* reload_context = Isolate::Current()->reload_context();
+  ASSERT(reload_context != NULL);
+
+  const Array& old_field_list = Array::Handle(old_cls.fields());
+  Field& old_field = Field::Handle();
+  String& old_name = String::Handle();
+
+  const Array& field_list = Array::Handle(fields());
+  Field& field = Field::Handle();
+  String& name = String::Handle();
+
+  Instance& value = Instance::Handle();
+  for (intptr_t i = 0; i < field_list.Length(); i++) {
+    field = Field::RawCast(field_list.At(i));
+    name = field.name();
+    if (field.is_static()) {
+      // Find the corresponding old field, if it exists, and migrate
+      // over the field value.
+      for (intptr_t j = 0; j < old_field_list.Length(); j++) {
+        old_field = Field::RawCast(old_field_list.At(j));
+        old_name = old_field.name();
+        if (name.Equals(old_name)) {
+          if (update_values) {
+            value = old_field.StaticValue();
+            field.SetStaticValue(value);
+          }
+          reload_context->AddStaticFieldMapping(old_field, field);
+        }
+      }
+    }
+  }
+}
+
+
+void Class::CopyCanonicalConstants(const Class& old_cls) const {
+  if (is_enum_class()) {
+    return;
+  }
+#if defined(DEBUG)
+  {
+    // Class has no canonical constants allocated.
+    const Array& my_constants = Array::Handle(constants());
+    ASSERT(my_constants.Length() == 0);
+  }
+#endif  // defined(DEBUG).
+  // Copy old constants into new class.
+  const Array& old_constants = Array::Handle(old_cls.constants());
+  if (old_constants.IsNull() || old_constants.Length() == 0) {
+    return;
+  }
+  TIR_Print("Copied %" Pd " canonical constants for class `%s`\n",
+            old_constants.Length(),
+            ToCString());
+  set_constants(old_constants);
+}
+
+
+void Class::CopyCanonicalTypes(const Class& old_cls) const {
+  const Object& old_canonical_types = Object::Handle(old_cls.canonical_types());
+  if (old_canonical_types.IsNull()) {
+    return;
+  }
+  set_canonical_types(old_canonical_types);
+}
+
+
+static intptr_t IndexOfEnum(const Array& enum_names, const String& name) {
+  ASSERT(!enum_names.IsNull());
+  ASSERT(!name.IsNull());
+  String& enum_name = String::Handle();
+  for (intptr_t i = 0; i < enum_names.Length(); i++) {
+    enum_name = String::RawCast(enum_names.At(i));
+    ASSERT(!enum_name.IsNull());
+    if (enum_name.Equals(name)) {
+      return i;
+    }
+  }
+
+  return -1;
+}
+
+
+static void UpdateEnumIndex(const Instance& enum_value,
+                            const Field& enum_index_field,
+                            const intptr_t index) {
+  enum_value.SetField(enum_index_field, Smi::Handle(Smi::New(index)));
+}
+
+
+// TODO(johnmccutchan): The code in the class finalizer canonicalizes all
+// instances and the values array. We probably should do the same thing.
+void Class::ReplaceEnum(const Class& old_enum) const {
+  // We only do this for finalized enum classes.
+  ASSERT(is_enum_class());
+  ASSERT(old_enum.is_enum_class());
+  ASSERT(is_finalized());
+  ASSERT(old_enum.is_finalized());
+
+  Thread* thread = Thread::Current();
+  IsolateReloadContext* reload_context = Isolate::Current()->reload_context();
+  ASSERT(reload_context != NULL);
+
+  TIR_Print("ReplaceEnum `%s` (%" Pd " and %" Pd ")\n",
+            ToCString(), id(), old_enum.id());
+
+  // Grab '_enum_names' from |old_enum|.
+  const Field& old_enum_names_field = Field::Handle(
+      old_enum.LookupStaticFieldAllowPrivate(Symbols::_EnumNames()));
+  ASSERT(!old_enum_names_field.IsNull());
+  const Array& old_enum_names =
+      Array::Handle(Array::RawCast(old_enum_names_field.StaticValue()));
+  ASSERT(!old_enum_names.IsNull());
+
+  // Grab 'values' from |old_enum|.
+  const Field& old_enum_values_field = Field::Handle(
+      old_enum.LookupStaticField(Symbols::Values()));
+  ASSERT(!old_enum_values_field.IsNull());
+  const Array& old_enum_values =
+      Array::Handle(Array::RawCast(old_enum_values_field.StaticValue()));
+  ASSERT(!old_enum_values.IsNull());
+
+  // Grab _enum_names from |this|.
+  const Field& enum_names_field = Field::Handle(
+      LookupStaticFieldAllowPrivate(Symbols::_EnumNames()));
+  ASSERT(!enum_names_field.IsNull());
+  Array& enum_names =
+      Array::Handle(Array::RawCast(enum_names_field.StaticValue()));
+  ASSERT(!enum_names.IsNull());
+
+  // Grab values from |this|.
+  const Field& enum_values_field = Field::Handle(
+      LookupStaticField(Symbols::Values()));
+  ASSERT(!enum_values_field.IsNull());
+  Array& enum_values =
+      Array::Handle(Array::RawCast(enum_values_field.StaticValue()));
+  ASSERT(!enum_values.IsNull());
+
+  // Grab the |index| field.
+  const Field& index_field =
+      Field::Handle(old_enum.LookupInstanceField(Symbols::Index()));
+  ASSERT(!index_field.IsNull());
+
+  // Build list of enum from |old_enum| that aren't present in |this|.
+  // This array holds pairs: (name, value).
+  const GrowableObjectArray& to_add =
+      GrowableObjectArray::Handle(GrowableObjectArray::New(Heap::kOld));
+  const String& enum_class_name = String::Handle(UserVisibleName());
+  String& enum_name = String::Handle();
+  String& enum_field_name = String::Handle();
+  Object& enum_value = Object::Handle();
+  Field& enum_field = Field::Handle();
+
+  TIR_Print("New version of enum has %" Pd " elements\n",
+            enum_values.Length());
+  TIR_Print("Old version of enum had %" Pd " elements\n",
+            old_enum_values.Length());
+
+  for (intptr_t i = 0; i < old_enum_names.Length(); i++) {
+    enum_name = String::RawCast(old_enum_names.At(i));
+    const intptr_t index_in_new_cls = IndexOfEnum(enum_names, enum_name);
+    if (index_in_new_cls < 0) {
+      // Doesn't exist in new enum, add.
+      TIR_Print("Adding enum value `%s` to %s\n",
+                enum_name.ToCString(),
+                this->ToCString());
+      enum_value = old_enum_values.At(i);
+      ASSERT(!enum_value.IsNull());
+      to_add.Add(enum_name);
+      to_add.Add(enum_value);
+    } else {
+      // Exists in both the new and the old.
+      TIR_Print("Moving enum value `%s` to %" Pd "\n",
+                enum_name.ToCString(),
+                index_in_new_cls);
+      // Grab old value.
+      enum_value = old_enum_values.At(i);
+      // Update index to the be new index.
+      UpdateEnumIndex(Instance::Cast(enum_value),
+                      index_field,
+                      index_in_new_cls);
+      // Chop off the 'EnumClass.'
+      enum_field_name = String::SubString(enum_name,
+                                          enum_class_name.Length() + 1);
+      ASSERT(!enum_field_name.IsNull());
+      // Grab the static field.
+      enum_field = LookupStaticField(enum_field_name);
+      ASSERT(!enum_field.IsNull());
+      // Use old value with updated index.
+      enum_field.SetStaticValue(Instance::Cast(enum_value), true);
+      enum_values.SetAt(index_in_new_cls, enum_value);
+      enum_names.SetAt(index_in_new_cls, enum_name);
+    }
+  }
+
+  if (to_add.Length() == 0) {
+    // Nothing to do.
+    TIR_Print("Found no missing enums in %s\n", ToCString());
+    return;
+  }
+
+  // Grow the values and enum_names arrays.
+  const intptr_t offset = enum_names.Length();
+  const intptr_t num_to_add = to_add.Length() / 2;
+  ASSERT(offset == enum_values.Length());
+  enum_names = Array::Grow(enum_names,
+                           enum_names.Length() + num_to_add,
+                           Heap::kOld);
+  enum_values = Array::Grow(enum_values,
+                            enum_values.Length() + num_to_add,
+                            Heap::kOld);
+
+  // Install new names and values into the grown arrays. Also, update
+  // the index of the new enum values and add static fields for the new
+  // enum values.
+  Field& enum_value_field = Field::Handle();
+  for (intptr_t i = 0; i < num_to_add; i++) {
+    const intptr_t target_index = offset + i;
+    enum_name = String::RawCast(to_add.At(i * 2));
+    enum_value = to_add.At(i * 2 + 1);
+
+    // Update the enum value's index into the new arrays.
+    TIR_Print("Updating index of %s in %s to %" Pd "\n",
+              enum_name.ToCString(),
+              ToCString(),
+              target_index);
+    UpdateEnumIndex(Instance::Cast(enum_value), index_field, target_index);
+
+    enum_names.SetAt(target_index, enum_name);
+    enum_values.SetAt(target_index, enum_value);
+
+    // Install new static field into class.
+    // Chop off the 'EnumClass.'
+    enum_field_name = String::SubString(enum_name,
+                                        enum_class_name.Length() + 1);
+    ASSERT(!enum_field_name.IsNull());
+    enum_field_name = Symbols::New(thread, enum_field_name);
+    enum_value_field = Field::New(enum_field_name,
+                                  /* is_static = */ true,
+                                  /* is_final = */ true,
+                                  /* is_const = */ true,
+                                  /* is_reflectable = */ true,
+                                  *this,
+                                  Object::dynamic_type(),
+                                  token_pos());
+    enum_value_field.set_has_initializer(false);
+    enum_value_field.SetStaticValue(Instance::Cast(enum_value), true);
+    enum_value_field.RecordStore(Instance::Cast(enum_value));
+    AddField(enum_value_field);
+  }
+
+  // Replace the arrays stored in the static fields.
+  enum_names_field.SetStaticValue(enum_names, true);
+  enum_values_field.SetStaticValue(enum_values, true);
+}
+
+
+void Class::PatchFieldsAndFunctions() const {
+  // Move all old functions and fields to a patch class so that they
+  // still refer to their original script.
+  const PatchClass& patch =
+      PatchClass::Handle(PatchClass::New(*this, Script::Handle(script())));
+  ASSERT(!patch.IsNull());
+
+  const Array& funcs = Array::Handle(functions());
+  Function& func = Function::Handle();
+  Object& owner = Object::Handle();
+  for (intptr_t i = 0; i < funcs.Length(); i++) {
+    func = Function::RawCast(funcs.At(i));
+    if ((func.token_pos() == TokenPosition::kMinSource) ||
+        func.IsClosureFunction()) {
+      // Eval functions do not need to have their script updated.
+      //
+      // Closure functions refer to the parent's script which we can
+      // rely on being updated for us, if necessary.
+      continue;
+    }
+
+    // If the source for this function is already patched, leave it alone.
+    owner = func.RawOwner();
+    ASSERT(!owner.IsNull());
+    if (!owner.IsPatchClass()) {
+      ASSERT(owner.raw() == this->raw());
+      func.set_owner(patch);
+    }
+  }
+
+  const Array& field_list = Array::Handle(fields());
+  Field& field = Field::Handle();
+  for (intptr_t i = 0; i < field_list.Length(); i++) {
+    field = Field::RawCast(field_list.At(i));
+    owner = field.RawOwner();
+    ASSERT(!owner.IsNull());
+    if (!owner.IsPatchClass()) {
+      ASSERT(owner.raw() == this->raw());
+      field.set_owner(patch);
+    }
+    field.ForceDynamicGuardedCidAndLength();
+  }
+}
+
+
+bool Class::CanReload(const Class& replacement) const {
+  ASSERT(IsolateReloadContext::IsSameClass(*this, replacement));
+
+  if (is_enum_class() && !replacement.is_enum_class()) {
+    IRC->ReportError(String::Handle(String::NewFormatted(
+        "Enum class cannot be redefined to be a non-enum class: %s",
+        ToCString())));
+    return false;
+  }
+
+  if (!is_enum_class() && replacement.is_enum_class()) {
+    IRC->ReportError(String::Handle(String::NewFormatted(
+        "Class cannot be redefined to be a enum class: %s",
+        ToCString())));
+    return false;
+  }
+
+  if (is_finalized()) {
+    const Error& error =
+        Error::Handle(replacement.EnsureIsFinalized(Thread::Current()));
+    if (!error.IsNull()) {
+      IRC->ReportError(error);
+      return false;
+    }
+    TIR_Print("Finalized replacement class for %s\n", ToCString());
+  }
+
+  if (is_finalized()) {
+    // Get the field maps for both classes. These field maps walk the class
+    // hierarchy.
+    const Array& fields =
+        Array::Handle(OffsetToFieldMap());
+    const Array& replacement_fields =
+        Array::Handle(replacement.OffsetToFieldMap());
+
+    // Check that we have the same number of fields.
+    if (fields.Length() != replacement_fields.Length()) {
+      IRC->ReportError(String::Handle(String::NewFormatted(
+          "Number of instance fields changed in %s", ToCString())));
+      return false;
+    }
+
+    if (NumTypeArguments() != replacement.NumTypeArguments()) {
+      IRC->ReportError(String::Handle(String::NewFormatted(
+          "Number of type arguments changed in %s", ToCString())));
+      return false;
+    }
+
+    // Verify that field names / offsets match across the entire hierarchy.
+    Field& field = Field::Handle();
+    String& field_name = String::Handle();
+    Field& replacement_field = Field::Handle();
+    String& replacement_field_name = String::Handle();
+    for (intptr_t i = 0; i < fields.Length(); i++) {
+      if (fields.At(i) == Field::null()) {
+        ASSERT(replacement_fields.At(i) == Field::null());
+        continue;
+      }
+      field = Field::RawCast(fields.At(i));
+      replacement_field = Field::RawCast(replacement_fields.At(i));
+      field_name = field.name();
+      replacement_field_name = replacement_field.name();
+      if (!field_name.Equals(replacement_field_name)) {
+        IRC->ReportError(String::Handle(String::NewFormatted(
+            "Name of instance field changed ('%s' vs '%s') in '%s'",
+            field_name.ToCString(),
+            replacement_field_name.ToCString(),
+            ToCString())));
+        return false;
+      }
+    }
+  } else if (is_prefinalized()) {
+    if (!replacement.is_prefinalized()) {
+      IRC->ReportError(String::Handle(String::NewFormatted(
+          "Original class ('%s') is prefinalized and replacement class ('%s')",
+          ToCString(), replacement.ToCString())));
+      return false;
+    }
+    if (instance_size() != replacement.instance_size()) {
+     IRC->ReportError(String::Handle(String::NewFormatted(
+         "Instance size mismatch between '%s' (%" Pd ") and replacement "
+         "'%s' ( %" Pd ")",
+         ToCString(),
+         instance_size(),
+         replacement.ToCString(),
+         replacement.instance_size())));
+     return false;
+    }
+  }
+
+  // native field count check.
+  if (num_native_fields() != replacement.num_native_fields()) {
+    IRC->ReportError(String::Handle(String::NewFormatted(
+        "Number of native fields changed in %s", ToCString())));
+    return false;
+  }
+
+  // TODO(johnmccutchan) type parameter count check.
+
+  TIR_Print("Class `%s` can be reloaded (%" Pd " and %" Pd ")\n",
+            ToCString(),
+            id(),
+            replacement.id());
+  return true;
+}
+
+
+bool Library::CanReload(const Library& replacement) const {
+  return true;
+}
+
+
+static const Function* static_call_target = NULL;
+
+void ICData::Reset(bool is_static_call) const {
+  // TODO(johnmccutchan): ICData should know whether or not it's for a
+  // static call.
+  if (is_static_call) {
+    const Function& old_target = Function::Handle(GetTargetAt(0));
+    if (old_target.IsNull()) {
+      FATAL("old_target is NULL.\n");
+    }
+    static_call_target = &old_target;
+    if (!old_target.is_static()) {
+      // TODO(johnmccutchan): Improve this.
+      TIR_Print("Cannot rebind super-call to %s from %s\n",
+                old_target.ToCString(),
+                Object::Handle(Owner()).ToCString());
+      return;
+    }
+    const String& selector = String::Handle(old_target.name());
+    const Class& cls = Class::Handle(old_target.Owner());
+    const Function& new_target =
+        Function::Handle(cls.LookupStaticFunction(selector));
+    if (new_target.IsNull()) {
+      // TODO(johnmccutchan): Improve this.
+      TIR_Print("Cannot rebind static call to %s from %s\n",
+                old_target.ToCString(),
+                Object::Handle(Owner()).ToCString());
+      return;
+    }
+    ClearAndSetStaticTarget(new_target);
+  } else {
+    ClearWithSentinel();
+  }
+}
+
+#endif  // !PRODUCT
+
+}   // namespace dart.