X-Git-Url: http://nitlanguage.org

diff --git a/src/vm.nit b/src/vm.nit
index 4dc29e9..3807ab7 100644
--- a/src/vm.nit
+++ b/src/vm.nit
@@ -17,7 +17,7 @@
 # Implementation of the Nit virtual machine
 module vm
 
-intrude import naive_interpreter
+import interpreter::naive_interpreter
 import model_utils
 import perfect_hashing
 
@@ -28,7 +28,7 @@ redef class ModelBuilder
 		self.toolcontext.info("*** NITVM STARTING ***", 1)
 
 		var interpreter = new VirtualMachine(self, mainmodule, arguments)
-		init_naive_interpreter(interpreter, mainmodule)
+		interpreter.start(mainmodule)
 
 		var time1 = get_time
 		self.toolcontext.info("*** NITVM STOPPING : {time1-time0} ***", 2)
@@ -44,6 +44,16 @@ class VirtualMachine super NaiveInterpreter
 	# Handles memory and garbage collection
 	var memory_manager: MemoryManager = new MemoryManager
 
+	# The unique instance of the `MInit` value
+	var initialization_value: Instance
+
+	init(modelbuilder: ModelBuilder, mainmodule: MModule, arguments: Array[String])
+	do
+		super
+		var init_type = new MInitType(mainmodule.model)
+		initialization_value = new MutableInstance(init_type)
+	end
+
 	# Subtyping test for the virtual machine
 	redef fun is_subtype(sub, sup: MType): Bool
 	do
@@ -96,7 +106,6 @@ class VirtualMachine super NaiveInterpreter
 		# Sub can be discovered inside a Generic type during the subtyping test
 		if not sub.mclass.loaded then create_class(sub.mclass)
 
-		if anchor == null then anchor = sub
 		if sup isa MGenericType then
 			var sub2 = sub.supertype_to(mainmodule, anchor, sup.mclass)
 			assert sub2.mclass == sup.mclass
@@ -138,28 +147,29 @@ class VirtualMachine super NaiveInterpreter
 
 		assert(recv isa MutableInstance)
 
-		recv.internal_attributes = init_internal_attributes(null_instance, recv.mtype.as(MClassType).mclass.all_mattributes(mainmodule, none_visibility).length)
+		recv.internal_attributes = init_internal_attributes(initialization_value, recv.mtype.as(MClassType).mclass.all_mattributes(mainmodule, none_visibility).length)
 		super
 	end
 
 	# Initialize the internal representation of an object (its attribute values)
-	private fun init_internal_attributes(null_instance: Instance, size: Int): Pointer
+	# `init_instance` is the initial value of attributes
+	private fun init_internal_attributes(init_instance: Instance, size: Int): Pointer
 		import Array[Instance].length, Array[Instance].[] `{
 
 		Instance* attributes = malloc(sizeof(Instance) * size);
 
 		int i;
 		for(i=0; i<size; i++)
-			attributes[i] = null_instance;
+			attributes[i] = init_instance;
 
-		Instance_incr_ref(null_instance);
+		Instance_incr_ref(init_instance);
 		return attributes;
 	`}
 
 	# Creates the runtime structures for this class
 	fun create_class(mclass: MClass) do	mclass.make_vt(self)
 
-	# Return the value of the attribute `mproperty for the object `recv
+	# Return the value of the attribute `mproperty` for the object `recv`
 	redef fun read_attribute(mproperty: MAttribute, recv: Instance): Instance
 	do
 		assert recv isa MutableInstance
@@ -170,15 +180,21 @@ class VirtualMachine super NaiveInterpreter
 		var i = read_attribute_ph(recv.internal_attributes, recv.vtable.internal_vtable,
 					recv.vtable.mask, id, mproperty.offset)
 
+		# If we get a `MInit` value, throw an error
+		if i == initialization_value then
+			fatal("Uninitialized attribute {mproperty.name}")
+			abort
+		end
+
 		return i
 	end
 
-	# Return the attribute value in `instance with a sequence of perfect_hashing
-	#     `instance is the attributes array of the receiver
-	#     `vtable is the pointer to the virtual table of the class (of the receiver)
-	#     `mask is the perfect hashing mask of the class
-	#     `id is the identifier of the class
-	#     `offset is the relative offset of this attribute
+	# Return the attribute value in `instance` with a sequence of perfect_hashing
+	#     `instance` is the attributes array of the receiver
+	#     `vtable` is the pointer to the virtual table of the class (of the receiver)
+	#     `mask` is the perfect hashing mask of the class
+	#     `id` is the identifier of the class
+	#     `offset` is the relative offset of this attribute
 	private fun read_attribute_ph(instance: Pointer, vtable: Pointer, mask: Int, id: Int, offset: Int): Instance `{
 		// Perfect hashing position
 		int hv = mask & id;
@@ -192,7 +208,7 @@ class VirtualMachine super NaiveInterpreter
 		return res;
 	`}
 
-	# Replace in `recv the value of the attribute `mproperty by `value
+	# Replace in `recv` the value of the attribute `mproperty` by `value`
 	redef fun write_attribute(mproperty: MAttribute, recv: Instance, value: Instance)
 	do
 		assert recv isa MutableInstance
@@ -205,12 +221,12 @@ class VirtualMachine super NaiveInterpreter
 	end
 
 	# Replace the value of an attribute in an instance
-	#     `instance is the attributes array of the receiver
-	#     `vtable is the pointer to the virtual table of the class (of the receiver)
-	#     `mask is the perfect hashing mask of the class
-	#     `id is the identifier of the class
-	#     `offset is the relative offset of this attribute
-	#     `value is the new value for this attribute
+	#     `instance` is the attributes array of the receiver
+	#     `vtable` is the pointer to the virtual table of the class (of the receiver)
+	#     `mask` is the perfect hashing mask of the class
+	#     `id` is the identifier of the class
+	#     `offset` is the relative offset of this attribute
+	#     `value` is the new value for this attribute
 	private fun write_attribute_ph(instance: Pointer, vtable: Pointer, mask: Int, id: Int, offset: Int, value: Instance) `{
 		// Perfect hashing position
 		int hv = mask & id;
@@ -222,6 +238,21 @@ class VirtualMachine super NaiveInterpreter
 		((Instance *)instance)[absolute_offset + offset] = value;
 		Instance_incr_ref(value);
 	`}
+
+	# Is the attribute `mproperty` initialized in the instance `recv`?
+	redef fun isset_attribute(mproperty: MAttribute, recv: Instance): Bool
+	do
+		assert recv isa MutableInstance
+
+		# Read the attribute value with internal perfect hashing read
+		# because we do not want to throw an error if the value is `initialization_value`
+		var id = mproperty.intro_mclassdef.mclass.vtable.id
+
+		var i = read_attribute_ph(recv.internal_attributes, recv.vtable.internal_vtable,
+					recv.vtable.mask, id, mproperty.offset)
+
+		return i != initialization_value
+	end
 end
 
 redef class MClass
@@ -244,19 +275,18 @@ redef class MClass
 	do
 		if loaded then return
 
-		# Superclasses contains all superclasses except self
-		var superclasses = new Array[MClass]
-		superclasses.add_all(ancestors)
+		# `superclasses` contains the order of superclasses for virtual tables
+		var superclasses = superclasses_ordering(v)
 		superclasses.remove(self)
-		v.mainmodule.linearize_mclasses(superclasses)
 
 		# Make_vt for super-classes
 		var ids = new Array[Int]
 		var nb_methods = new Array[Int]
 		var nb_attributes = new Array[Int]
 
-		# Represents the absolute offsets from the beginning of the table for attributes and methods
+		# Absolute offset of the beginning of the attributes table
 		var offset_attributes = 0
+		# Absolute offset of the beginning of the methods table
 		var offset_methods = 0
 
 		for parent in superclasses do
@@ -277,7 +307,7 @@ redef class MClass
 			nb_methods.push(methods)
 			nb_attributes.push(attributes)
 
-			# Update `positions_attributes and `positions_methods in `parent
+			# Update `positions_attributes` and `positions_methods` in `parent`
 			update_positions(offset_attributes, offset_methods, parent)
 
 			offset_attributes += attributes
@@ -346,7 +376,7 @@ redef class MClass
 
 	# Computes delta for each class
 	# A delta represents the offset for this group of attributes in the object
-	#     `nb_attributes : number of attributes for each class (classes are linearized from Object to current)
+	#     `nb_attributes` : number of attributes for each class (classes are linearized from Object to current)
 	#     return deltas for each class
 	private fun calculate_delta(nb_attributes: Array[Int]): Array[Int]
 	do
@@ -361,9 +391,85 @@ redef class MClass
 		return deltas
 	end
 
-	# Update positions of self class in `parent
-	#     `attributes_offset: absolute offset of introduced attributes
-	#     `methods_offset: absolute offset of introduced methods
+	# Order superclasses of self
+	# Return the order of superclasses in runtime structures of this class
+	private fun superclasses_ordering(v: VirtualMachine): Array[MClass]
+	do
+		var superclasses = new Array[MClass]
+		superclasses.add_all(ancestors)
+
+		var res = new Array[MClass]
+		if superclasses.length > 1 then
+			# Starting at self
+			var ordering = self.dfs(v, res)
+
+			return ordering
+		else
+			# There is no super-class, self is Object
+			return superclasses
+		end
+	end
+
+	# A kind of Depth-First-Search for superclasses ordering
+	#     `v` : the current executed instance of VirtualMachine
+	#     `res` : Result Array, ie current superclasses ordering
+	private fun dfs(v: VirtualMachine, res: Array[MClass]): Array[MClass]
+	do
+		# Add this class at the beginning
+		res.insert(self, 0)
+
+		var direct_parents = self.in_hierarchy(v.mainmodule).direct_greaters.to_a
+
+		if direct_parents.length > 1 then
+			# Prefix represents the class which has the most properties
+			# we try to choose it in first to reduce the number of potential recompilations
+			var prefix = null
+			var max = -1
+			for cl in direct_parents do
+				# If we never have visited this class
+				if not res.has(cl) then
+					var properties_length = cl.all_mproperties(v.mainmodule, none_visibility).length
+					if properties_length > max then
+						max = properties_length
+						prefix = cl
+					end
+				end
+			end
+
+			if prefix != null then
+				# Add the prefix class ordering at the beginning of our sequence
+				var prefix_res = new Array[MClass]
+				prefix_res = prefix.dfs(v, prefix_res)
+
+				# Then we recurse on other classes
+				for cl in direct_parents do
+					if cl != prefix then
+						res = new Array[MClass]
+						res = cl.dfs(v, res)
+
+						for cl_res in res do
+							if not prefix_res.has(cl_res) then prefix_res.push(cl_res)
+						end
+					end
+				end
+				res = prefix_res
+			end
+
+			res.push(self)
+		else
+			if direct_parents.length > 0 then
+				res = direct_parents.first.dfs(v, res)
+			end
+		end
+
+		if not res.has(self) then res.push(self)
+
+		return res
+	end
+
+	# Update positions of self class in `parent`
+	#     `attributes_offset`: absolute offset of introduced attributes
+	#     `methods_offset`: absolute offset of introduced methods
 	private fun update_positions(attributes_offsets: Int, methods_offset:Int, parent: MClass)
 	do
 		parent.positions_attributes[self] = attributes_offsets
@@ -383,6 +489,29 @@ redef class MutableInstance
 	var internal_attributes: Pointer
 end
 
+# Is the type of the initial value inside attributes
+class MInitType
+	super MType
+
+	redef var model: Model
+	protected init(model: Model)
+	do
+		self.model = model
+	end
+
+	redef fun to_s do return "InitType"
+	redef fun as_nullable do return self
+	redef fun need_anchor do return false
+	redef fun resolve_for(mtype, anchor, mmodule, cleanup_virtual) do return self
+	redef fun can_resolve_for(mtype, anchor, mmodule) do return true
+
+	redef fun collect_mclassdefs(mmodule) do return new HashSet[MClassDef]
+
+	redef fun collect_mclasses(mmodule) do return new HashSet[MClass]
+
+	redef fun collect_mtypes(mmodule) do return new HashSet[MClassType]
+end
+
 # A VTable contains the virtual method table for the dispatch
 # and informations to perform subtyping tests
 class VTable