redef fun init_instance(recv: Instance)
do
if not recv.mtype.as(MClassType).mclass.loaded then create_class(recv.mtype.as(MClassType).mclass)
- super
recv.vtable = recv.mtype.as(MClassType).mclass.vtable
+
+ assert(recv isa MutableInstance)
+
+ recv.internal_attributes = init_internal_attributes(null_instance, recv.mtype.as(MClassType).mclass.cached_attributes.length)
+
+ super
end
-
+
+ # Initialize the internal representation of an object (its attribute values)
+ private fun init_internal_attributes(null_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;
+
+ 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
+ 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 = read_attribute_ph(recv.internal_attributes, recv.vtable.internal_vtable,
+ recv.vtable.mask, id, mproperty.offset)
+
+ 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
+ private fun read_attribute_ph(instance: Pointer, vtable: Pointer, mask: Int, id: Int, offset: Int): Instance `{
+ // Perfect hashing position
+ int hv = mask & id;
+ long unsigned int *pointer = (long unsigned int*)(((long int *)vtable)[-hv]);
+
+ // pointer+1 is the position where the delta of the class is
+ int absolute_offset = *(pointer + 1);
+
+ Instance res = ((Instance *)instance)[absolute_offset + 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
+
+ # TODO : ugly hack
+ recv.attributes[mproperty] = value
+
+ # Replace the old value of mproperty in recv
+ write_attribute_ph(recv.internal_attributes, recv.vtable.internal_vtable,
+ recv.vtable.mask, id, mproperty.offset, value)
+ 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
+ private fun write_attribute_ph(instance: Pointer, vtable: Pointer, mask: Int, id: Int, offset: Int, value: Instance) `{
+ // Perfect hashing position
+ int hv = mask & id;
+ long unsigned int *pointer = (long unsigned int*)(((long int *)vtable)[-hv]);
+
+ // pointer+1 is the position where the delta of the class is
+ int absolute_offset = *(pointer + 1);
+
+ ((Instance *)instance)[absolute_offset + offset] = value;
+ `}
end
redef class MClass
# True when the class is effectively loaded by the vm, false otherwise
var loaded: Bool = false
+ # Cached attributes for faster instanciations of this class
+ var cached_attributes: Array[MAttribute] = new Array[MAttribute]
+
# Allocates a VTable for this class and gives it an id
private fun make_vt(v: VirtualMachine)
do
# Make_vt for super-classes
var ids = new Array[Int]
var nb_methods = new Array[Int]
+ var nb_attributes = new Array[Int]
for parent in superclasses do
if parent.vtable == null then parent.make_vt(v)
# Get the number of introduced methods and attributes for this class
var methods = 0
+ var attributes = 0
for p in parent.intro_mproperties(none_visibility) do
if p isa MMethod then methods += 1
+ if p isa MAttribute then
+ attributes += 1
+ end
end
ids.push(parent.vtable.id)
nb_methods.push(methods)
+ nb_attributes.push(attributes)
end
# When all super-classes have their identifiers and vtables, allocate current one
- allocate_vtable(v, ids, nb_methods)
+ allocate_vtable(v, ids, nb_methods, nb_attributes)
loaded = true
# The virtual table now needs to be filled with pointer to methods
end
# Allocate a single vtable
# ids : Array of superclasses identifiers
# nb_methods : Array which contain the number of introducted methods for each class in ids
- private fun allocate_vtable(v: VirtualMachine, ids: Array[Int], nb_methods: Array[Int])
+ # nb_attributes : Array which contain the number of introducted attributes for each class in ids
+ private fun allocate_vtable(v: VirtualMachine, ids: Array[Int], nb_methods: Array[Int], nb_attributes: Array[Int])
do
vtable = new VTable
var idc = new Array[Int]
ids_total.push(vtable.id)
var nb_methods_total = new Array[Int]
- var methods = 0
+ var nb_attributes_total = new Array[Int]
+
+ var self_methods = 0
+ var self_attributes = 0
+
+ # For self attributes, fixing offsets
+ var relative_offset = 0
for p in intro_mproperties(none_visibility) do
- if p isa MMethod then methods += 1
+ if p isa MMethod then self_methods += 1
+ if p isa MAttribute then
+ self_attributes += 1
+ p.offset = relative_offset
+ relative_offset += 1
+ cached_attributes.push(p)
+ end
end
+
nb_methods_total.add_all(nb_methods)
- nb_methods_total.push(methods)
-
- vtable.internal_vtable = v.memory_manager.init_vtable(ids_total, nb_methods_total, vtable.mask)
+ nb_methods_total.push(self_methods)
+
+ nb_attributes_total.add_all(nb_attributes)
+ nb_attributes_total.push(self_attributes)
+
+ # 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)
+ 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
+ private fun calculate_delta(nb_attributes: Array[Int]): Array[Int]
+ do
+ var deltas = new Array[Int]
+
+ var total = 0
+ for nb in nb_attributes do
+ deltas.push(total)
+ total += nb
+ end
+
+ return deltas
end
end
+redef class MAttribute
+ # Represents the relative offset of this attribute in the runtime instance
+ var offset: Int
+end
+
+# Redef MutableInstance to improve implementation of attributes in objects
+redef class MutableInstance
+
+ # C-array to store pointers to attributes of this Object
+ var internal_attributes: Pointer
+end
+
# A VTable contains the virtual method table for the dispatch
# and informations to perform subtyping tests
class VTable
class MemoryManager
# Allocate and fill a virtual table
- fun init_vtable(ids: Array[Int], nb_methods: Array[Int], mask: Int): Pointer
+ fun init_vtable(ids: Array[Int], nb_methods: Array[Int], nb_attributes: Array[Int], mask: Int): Pointer
do
# Allocate in C current virtual table
- var res = intern_init_vtable(ids, nb_methods, mask)
+ var res = intern_init_vtable(ids, nb_methods, nb_attributes, mask)
return res
end
# Construct virtual tables with a bi-dimensional layout
- private fun intern_init_vtable(ids: Array[Int], nb_methods: Array[Int], mask: Int): Pointer
+ private fun intern_init_vtable(ids: Array[Int], nb_methods: Array[Int], deltas: Array[Int], mask: Int): Pointer
import Array[Int].length, Array[Int].[] `{
// Allocate and fill current virtual table
int hv = mask & Array_of_Int__index(ids, i);
vtable[current_size] = Array_of_Int__index(ids, i);
+ vtable[current_size + 1] = Array_of_Int__index(deltas, i);
vtable[-hv] = (long unsigned int)&(vtable[current_size]);
current_size += 2;
return vtable;
`}
-end
+end
\ No newline at end of file
nitlanguage / nit.git / commitdiff