# Perfect hashing and perfect numbering
var ph: Perfecthashing = new Perfecthashing
- # Handles memory and garbage collection
+ # Handles memory allocated in C
var memory_manager: MemoryManager = new MemoryManager
# The unique instance of the `MInit` value
init(modelbuilder: ModelBuilder, mainmodule: MModule, arguments: Array[String])
do
- super
var init_type = new MInitType(mainmodule.model)
initialization_value = new MutableInstance(init_type)
+ super
end
# Subtyping test for the virtual machine
recv.vtable = recv.mtype.as(MClassType).mclass.vtable
- assert(recv isa MutableInstance)
+ assert recv isa MutableInstance
recv.internal_attributes = init_internal_attributes(initialization_value, recv.mtype.as(MClassType).mclass.all_mattributes(mainmodule, none_visibility).length)
super
end
+ # Associate a `PrimitiveInstance` to its `VTable`
+ redef fun init_instance_primitive(recv: Instance)
+ do
+ if not recv.mtype.as(MClassType).mclass.loaded then create_class(recv.mtype.as(MClassType).mclass)
+
+ recv.vtable = recv.mtype.as(MClassType).mclass.vtable
+ end
+
+ # Create a virtual table for this `MClass` if not already done
+ redef fun get_primitive_class(name: String): MClass
+ do
+ var mclass = super
+
+ if not mclass.loaded then create_class(mclass)
+
+ return mclass
+ end
+
# Initialize the internal representation of an object (its attribute values)
# `init_instance` is the initial value of attributes
private fun init_internal_attributes(init_instance: Instance, size: Int): Pointer
# Creates the runtime structures for this class
fun create_class(mclass: MClass) do mclass.make_vt(self)
+ # Execute `mproperty` for a `args` (where `args[0]` is the receiver).
+ redef fun send(mproperty: MMethod, args: Array[Instance]): nullable Instance
+ do
+ var recv = args.first
+ var mtype = recv.mtype
+ var ret = send_commons(mproperty, args, mtype)
+ if ret != null then return ret
+
+ var propdef = method_dispatch(mproperty, recv.vtable.as(not null))
+
+ return self.call(propdef, args)
+ end
+
+ # Method dispatch, for a given global method `mproperty`
+ # returns the most specific local method in the class corresponding to `vtable`
+ private fun method_dispatch(mproperty: MMethod, vtable: VTable): MMethodDef
+ do
+ return method_dispatch_ph(vtable.internal_vtable, vtable.mask,
+ mproperty.intro_mclassdef.mclass.vtable.id, mproperty.offset)
+ end
+
+ # Execute a method dispatch with perfect hashing
+ private fun method_dispatch_ph(vtable: Pointer, mask: Int, id: Int, offset: Int): MMethodDef `{
+ // Perfect hashing position
+ int hv = mask & id;
+ long unsigned int *pointer = (long unsigned int*)(((long int *)vtable)[-hv]);
+
+ // pointer+2 is the position where methods are
+ // Add the offset of property and get the method implementation
+ MMethodDef propdef = (MMethodDef)*(pointer + 2 + offset);
+
+ return propdef;
+ `}
+
# 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
- # Read the attribute value with perfect hashing
- var id = mproperty.intro_mclassdef.mclass.vtable.id
+ var i: Instance
- var i = read_attribute_ph(recv.internal_attributes, recv.vtable.internal_vtable,
+ if mproperty.intro_mclassdef.mclass.positions_attributes[recv.mtype.as(MClassType).mclass] != -1 then
+ # if this attribute class has an unique position for this receiver, then use direct access
+ i = read_attribute_sst(recv.internal_attributes, mproperty.absolute_offset)
+ else
+ # Otherwise, read the attribute value with perfect hashing
+ var id = mproperty.intro_mclassdef.mclass.vtable.id
+
+ i = read_attribute_ph(recv.internal_attributes, recv.vtable.internal_vtable,
recv.vtable.mask, id, mproperty.offset)
+ end
# If we get a `MInit` value, throw an error
if i == initialization_value then
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
+ # * `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;
return res;
`}
+ # Return the attribute value in `instance` with a direct access (SST)
+ # * `instance` is the attributes array of the receiver
+ # * `offset` is the absolute offset of this attribute
+ private fun read_attribute_sst(instance: Pointer, offset: Int): Instance `{
+ /* We can make a direct access to the attribute value
+ because this attribute is always at the same position
+ for the class of this receiver */
+ Instance res = ((Instance *)instance)[offset];
+
+ return res;
+ `}
+
# 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
- var id = mproperty.intro_mclassdef.mclass.vtable.id
-
# Replace the old value of mproperty in recv
- write_attribute_ph(recv.internal_attributes, recv.vtable.internal_vtable,
+ if mproperty.intro_mclassdef.mclass.positions_attributes[recv.mtype.as(MClassType).mclass] != -1 then
+ # if this attribute class has an unique position for this receiver, then use direct access
+ write_attribute_sst(recv.internal_attributes, mproperty.absolute_offset, value)
+ else
+ # Otherwise, use perfect hashing to replace the old value
+ var id = mproperty.intro_mclassdef.mclass.vtable.id
+
+ write_attribute_ph(recv.internal_attributes, recv.vtable.internal_vtable,
recv.vtable.mask, id, mproperty.offset, value)
+ end
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;
Instance_incr_ref(value);
`}
+ # Replace the value of an attribute in an instance with direct access
+ # * `instance` is the attributes array of the receiver
+ # * `offset` is the absolute offset of this attribute
+ # * `value` is the new value for this attribute
+ private fun write_attribute_sst(instance: Pointer, offset: Int, value: Instance) `{
+ // Direct access to the position with the absolute offset
+ ((Instance *)instance)[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
var nb_methods = new Array[Int]
var nb_attributes = new Array[Int]
- # Absolute offset of the beginning of the attributes table
+ # Absolute offset of attribute from the beginning of the attributes table
var offset_attributes = 0
- # Absolute offset of the beginning of the methods table
+ # Absolute offset of method from the beginning of the methods table
var offset_methods = 0
+ # The previous element in `superclasses`
+ var previous_parent: nullable MClass = null
+ if superclasses.length > 0 then previous_parent = superclasses[0]
for parent in superclasses do
if not parent.loaded then parent.make_vt(v)
for p in parent.intro_mproperties(none_visibility) do
if p isa MMethod then methods += 1
- if p isa MAttribute then
- attributes += 1
- end
+ if p isa MAttribute then attributes += 1
end
ids.push(parent.vtable.id)
nb_methods.push(methods)
nb_attributes.push(attributes)
- # Update `positions_attributes` and `positions_methods` in `parent`
- update_positions(offset_attributes, offset_methods, parent)
+ # Update `positions_attributes` and `positions_methods` in `parent`.
+ # If the position is invariant for this parent, store this position
+ # else store a special value (-1)
+ var pos_attr = -1
+ var pos_meth = -1
+
+ if previous_parent.as(not null).positions_attributes[parent] == offset_attributes then pos_attr = offset_attributes
+ if previous_parent.as(not null).positions_methods[parent] == offset_methods then pos_meth = offset_methods
+
+ parent.update_positions(pos_attr, pos_meth, self)
offset_attributes += attributes
offset_methods += methods
# When all super-classes have their identifiers and vtables, allocate current one
allocate_vtable(v, ids, nb_methods, nb_attributes, offset_attributes, offset_methods)
loaded = true
+
# The virtual table now needs to be filled with pointer to methods
+ superclasses.add(self)
+ for cl in superclasses do
+ fill_vtable(v, vtable.as(not null), cl)
+ end
end
# Allocate a single vtable
- # `ids : Array of superclasses identifiers
- # `nb_methods : Array which contain the number of introduced methods for each class in ids
- # `nb_attributes : Array which contain the number of introduced attributes for each class in ids
- # `offset_attributes : Offset from the beginning of the table of the group of attributes
- # `offset_methods : Offset from the beginning of the table of the group of methods
+ # * `ids : Array of superclasses identifiers
+ # * `nb_methods : Array which contain the number of introduced methods for each class in ids
+ # * `nb_attributes : Array which contain the number of introduced attributes for each class in ids
+ # * `offset_attributes : Offset from the beginning of the table of the group of attributes
+ # * `offset_methods : Offset from the beginning of the table of the group of methods
private fun allocate_vtable(v: VirtualMachine, ids: Array[Int], nb_methods: Array[Int], nb_attributes: Array[Int],
offset_attributes: Int, offset_methods: Int)
do
var self_methods = 0
var nb_introduced_attributes = 0
- # For self attributes, fixing offsets
- var relative_offset = 0
+ # Fixing offsets for self attributes and methods
+ var relative_offset_attr = 0
+ var relative_offset_meth = 0
for p in intro_mproperties(none_visibility) do
- if p isa MMethod then self_methods += 1
+ if p isa MMethod then
+ self_methods += 1
+ p.offset = relative_offset_meth
+ p.absolute_offset = offset_methods + relative_offset_meth
+ relative_offset_meth += 1
+ end
if p isa MAttribute then
nb_introduced_attributes += 1
- p.offset = relative_offset
- relative_offset += 1
+ p.offset = relative_offset_attr
+ p.absolute_offset = offset_attributes + relative_offset_attr
+ relative_offset_attr += 1
end
end
nb_attributes_total.push(nb_introduced_attributes)
# Save the offsets of self class
- offset_attributes += nb_introduced_attributes
- offset_methods += self_methods
update_positions(offset_attributes, offset_methods, self)
# Since we have the number of attributes for each class, calculate the delta
- var d = calculate_delta(nb_attributes_total)
- vtable.internal_vtable = v.memory_manager.init_vtable(ids_total, nb_methods_total, d, vtable.mask)
+ var deltas = calculate_delta(nb_attributes_total)
+ vtable.internal_vtable = v.memory_manager.init_vtable(ids_total, nb_methods_total, deltas, vtable.mask)
+ end
+
+ # Fill the vtable with methods of `self` class
+ # * `v` : Current instance of the VirtualMachine
+ # * `table` : the table of self class, will be filled with its methods
+ private fun fill_vtable(v:VirtualMachine, table: VTable, cl: MClass)
+ do
+ var methods = new Array[MMethodDef]
+ for m in cl.intro_mproperties(none_visibility) do
+ if m isa MMethod then
+ # `propdef` is the most specific implementation for this MMethod
+ var propdef = m.lookup_first_definition(v.mainmodule, self.intro.bound_mtype)
+ methods.push(propdef)
+ end
+ end
+
+ # Call a method in C to put propdefs of self methods in the vtables
+ v.memory_manager.put_methods(vtable.internal_vtable, vtable.mask, cl.vtable.id, methods)
end
# 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)
- # return deltas for each class
+ # *`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
var deltas = new Array[Int]
end
# A kind of Depth-First-Search for superclasses ordering
- # `v` : the current executed instance of VirtualMachine
- # `res` : Result Array, ie current 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
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)
+ # Update positions of the class `cl`
+ # * `attributes_offset`: absolute offset of introduced attributes
+ # * `methods_offset`: absolute offset of introduced methods
+ private fun update_positions(attributes_offsets: Int, methods_offset:Int, cl: MClass)
do
- parent.positions_attributes[self] = attributes_offsets
- parent.positions_methods[self] = methods_offset
+ positions_attributes[cl] = attributes_offsets
+ positions_methods[cl] = methods_offset
end
end
redef class MAttribute
- # Represents the relative offset of this attribute in the runtime instance
+ # Relative offset of this attribute in the runtime instance
+ # (beginning of the block of its introducing class)
var offset: Int
+
+ # Absolute offset of this attribute in the runtime instance (beginning of the attribute table)
+ var absolute_offset: Int
+end
+
+redef class MMethod
+ # Relative offset of this method in the virtual table (from the beginning of the block)
+ var offset: Int
+
+ # Absolute offset of this method in the virtual table (from the beginning of the vtable)
+ var absolute_offset: Int
end
# Redef MutableInstance to improve implementation of attributes in objects
var internal_attributes: Pointer
end
+# Redef to associate an `Instance` to its `VTable`
+redef class Instance
+ var vtable: nullable VTable
+end
+
# Is the type of the initial value inside attributes
class MInitType
super MType
var classname: String is noinit
end
-redef class Instance
- var vtable: nullable VTable
-end
-
# Handle memory, used for allocate virtual table and associated structures
class MemoryManager
return vtable;
`}
+
+ # Put implementation of methods of a class in `vtable`
+ # * `vtable` : Pointer to the C-virtual table
+ # * `mask` : perfect-hashing mask of the class corresponding to the vtable
+ # * `id` : id of the target class
+ # * `methods` : array of MMethodDef of the target class
+ fun put_methods(vtable: Pointer, mask: Int, id: Int, methods: Array[MMethodDef])
+ import Array[MMethodDef].length, Array[MMethodDef].[] `{
+
+ // Get the area to fill with methods by a sequence of perfect hashing
+ int hv = mask & id;
+ long unsigned int *pointer = (long unsigned int*)(((long unsigned int *)vtable)[-hv]);
+
+ // pointer+2 is the beginning of the area for methods implementation
+ int length = Array_of_MMethodDef_length(methods);
+ long unsigned int *area = (pointer + 2);
+ int i;
+
+ for(i=0; i<length; i++)
+ {
+ MMethodDef method = Array_of_MMethodDef__index(methods, i);
+ area[i] = (long unsigned int)method;
+ MMethodDef_incr_ref(method);
+ }
+ `}
end
nitlanguage / nit.git / blobdiff