1 # This file is part of NIT ( http://www.nitlanguage.org ).
3 # Copyright 2014 Julien Pagès <julien.pages@lirmm.fr>
5 # Licensed under the Apache License, Version 2.0 (the "License");
6 # you may not use this file except in compliance with the License.
7 # You may obtain a copy of the License at
9 # http://www.apache.org/licenses/LICENSE-2.0
11 # Unless required by applicable law or agreed to in writing, software
12 # distributed under the License is distributed on an "AS IS" BASIS,
13 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 # See the License for the specific language governing permissions and
15 # limitations under the License.
17 # Implementation of the Nit virtual machine
20 import interpreter
::naive_interpreter
21 import perfect_hashing
23 redef class ModelBuilder
24 fun run_virtual_machine
(mainmodule
: MModule, arguments
: Array[String])
27 self.toolcontext
.info
("*** NITVM STARTING ***", 1)
29 var interpreter
= new VirtualMachine(self, mainmodule
, arguments
)
30 interpreter
.start
(mainmodule
)
33 self.toolcontext
.info
("*** NITVM STOPPING : {time1-time0} ***", 2)
37 # A virtual machine based on the naive_interpreter
38 class VirtualMachine super NaiveInterpreter
40 # Perfect hashing and perfect numbering
41 var ph
: Perfecthashing = new Perfecthashing
43 # Handles memory allocated in C
44 var memory_manager
: MemoryManager = new MemoryManager
46 # The unique instance of the `MInit` value
47 var initialization_value
: Instance is noinit
51 var init_type
= new MInitType(mainmodule
.model
)
52 initialization_value
= new MutableInstance(init_type
)
56 # Runtime subtyping test
57 redef fun is_subtype
(sub
, sup
: MType): Bool
59 if sub
== sup
then return true
61 var anchor
= self.frame
.arguments
.first
.mtype
.as(MClassType)
63 # `sub` or `sup` are formal or virtual types, resolve them to concrete types
64 if sub
isa MParameterType or sub
isa MVirtualType then
65 sub
= sub
.resolve_for
(anchor
.mclass
.mclass_type
, anchor
, mainmodule
, false)
67 if sup
isa MParameterType or sup
isa MVirtualType then
68 sup
= sup
.resolve_for
(anchor
.mclass
.mclass_type
, anchor
, mainmodule
, false)
71 var sup_accept_null
= false
72 if sup
isa MNullableType then
73 sup_accept_null
= true
75 else if sup
isa MNullType then
76 sup_accept_null
= true
79 # Can `sub` provides null or not?
80 # Thus we can match with `sup_accept_null`
81 # Also discard the nullable marker if it exists
82 if sub
isa MNullableType then
83 if not sup_accept_null
then return false
85 else if sub
isa MNullType then
86 return sup_accept_null
88 # Now the case of direct null and nullable is over
90 if sub
isa MParameterType or sub
isa MVirtualType then
91 sub
= sub
.anchor_to
(mainmodule
, anchor
)
92 # Manage the second layer of null/nullable
93 if sub
isa MNullableType then
94 if not sup_accept_null
then return false
96 else if sub
isa MNullType then
97 return sup_accept_null
101 assert sub
isa MClassType
103 # `sup` accepts only null
104 if sup
isa MNullType then return false
106 assert sup
isa MClassType
108 # `sub` and `sup` can be discovered inside a Generic type during the subtyping test
109 if not sup
.mclass
.loaded
then create_class
(sup
.mclass
)
110 if not sub
.mclass
.loaded
then create_class
(sub
.mclass
)
112 # For now, always use perfect hashing for subtyping test
113 var super_id
= sup
.mclass
.vtable
.id
114 var mask
= sub
.mclass
.vtable
.mask
116 var res
= inter_is_subtype_ph
(super_id
, mask
, sub
.mclass
.vtable
.internal_vtable
)
117 if res
== false then return false
118 # sub and sup can be generic types, each argument of generics has to be tested
120 if not sup
isa MGenericType then return true
121 var sub2
= sub
.supertype_to
(mainmodule
, anchor
, sup
.mclass
)
123 # Test each argument of a generic by recursive calls
124 for i
in [0..sup
.mclass
.arity
[ do
125 var sub_arg
= sub2
.arguments
[i
]
126 var sup_arg
= sup
.arguments
[i
]
127 var res2
= is_subtype
(sub_arg
, sup_arg
)
128 if res2
== false then return false
133 # Subtyping test with perfect hashing
134 private fun inter_is_subtype_ph
(id
: Int, mask
:Int, vtable
: Pointer): Bool `{
135 // hv is the position in hashtable
138 // Follow the pointer to somewhere in the vtable
139 long unsigned int *offset = (long unsigned int*)(((long int *)vtable)[-hv]);
141 // If the pointed value is corresponding to the identifier, the test is true, otherwise false
142 return *offset == id;
145 # Subtyping test with Cohen test (direct access)
146 private fun inter_is_subtype_sst
(id
: Int, position
: Int, vtable
: Pointer): Bool `{
147 // Direct access to the position given in parameter
148 int tableid = (long unsigned int)((long int *)vtable)[position];
150 return id == tableid;
153 # Redef init_instance to simulate the loading of a class
154 redef fun init_instance
(recv
: Instance)
156 if not recv
.mtype
.as(MClassType).mclass
.loaded
then create_class
(recv
.mtype
.as(MClassType).mclass
)
158 recv
.vtable
= recv
.mtype
.as(MClassType).mclass
.vtable
160 assert recv
isa MutableInstance
162 recv
.internal_attributes
= init_internal_attributes
(initialization_value
, recv
.mtype
.as(MClassType).mclass
.mattributes
.length
)
166 # Associate a `PrimitiveInstance` to its `VTable`
167 redef fun init_instance_primitive
(recv
: Instance)
169 if not recv
.mtype
.as(MClassType).mclass
.loaded
then create_class
(recv
.mtype
.as(MClassType).mclass
)
171 recv
.vtable
= recv
.mtype
.as(MClassType).mclass
.vtable
174 # Create a virtual table for this `MClass` if not already done
175 redef fun get_primitive_class
(name
: String): MClass
179 if not mclass
.loaded
then create_class
(mclass
)
184 # Initialize the internal representation of an object (its attribute values)
185 # `init_instance` is the initial value of attributes
186 private fun init_internal_attributes
(init_instance
: Instance, size
: Int): Pointer
187 import Array[Instance].length
, Array[Instance].[] `{
189 Instance* attributes = malloc(sizeof(Instance) * size);
192 for(i=0; i<size; i++)
193 attributes[i] = init_instance;
195 Instance_incr_ref(init_instance);
199 # Creates the runtime structures for this class
200 fun create_class
(mclass
: MClass) do mclass
.make_vt
(self)
202 # Execute `mproperty` for a `args` (where `args[0]` is the receiver).
203 redef fun send
(mproperty
: MMethod, args
: Array[Instance]): nullable Instance
205 var recv
= args
.first
206 var mtype
= recv
.mtype
207 var ret
= send_commons
(mproperty
, args
, mtype
)
208 if ret
!= null then return ret
210 var propdef
= method_dispatch
(mproperty
, recv
.vtable
.as(not null), recv
)
212 return self.call
(propdef
, args
)
215 # Method dispatch, for a given global method `mproperty`
216 # returns the most specific local method in the class corresponding to `vtable`
217 private fun method_dispatch
(mproperty
: MMethod, vtable
: VTable, recv
: Instance): MMethodDef
219 if mproperty
.intro_mclassdef
.mclass
.positions_methods
[recv
.mtype
.as(MClassType).mclass
] != -1 then
220 return method_dispatch_sst
(vtable
.internal_vtable
, mproperty
.absolute_offset
)
222 return method_dispatch_ph
(vtable
.internal_vtable
, vtable
.mask
,
223 mproperty
.intro_mclassdef
.mclass
.vtable
.id
, mproperty
.offset
)
227 # Execute a method dispatch with perfect hashing
228 private fun method_dispatch_ph
(vtable
: Pointer, mask
: Int, id
: Int, offset
: Int): MMethodDef `{
229 // Perfect hashing position
231 long unsigned int *pointer = (long unsigned int*)(((long int *)vtable)[-hv]);
233 // pointer+2 is the position where methods are
234 // Add the offset of property and get the method implementation
235 MMethodDef propdef = (MMethodDef)*(pointer + 2 + offset);
240 # Execute a method dispatch with direct access and return the appropriate `MMethodDef`
241 # `vtable` : Pointer to the internal pointer of the class
242 # `absolute_offset` : Absolute offset from the beginning of the virtual table
243 private fun method_dispatch_sst
(vtable
: Pointer, absolute_offset
: Int): MMethodDef `{
244 // pointer+2 is the position where methods are
245 // Add the offset of property and get the method implementation
246 MMethodDef propdef = (MMethodDef)((long int *)vtable)[absolute_offset];
251 # Return the value of the attribute `mproperty` for the object `recv`
252 redef fun read_attribute
(mproperty
: MAttribute, recv
: Instance): Instance
254 assert recv
isa MutableInstance
258 if mproperty
.intro_mclassdef
.mclass
.positions_attributes
[recv
.mtype
.as(MClassType).mclass
] != -1 then
259 # if this attribute class has an unique position for this receiver, then use direct access
260 i
= read_attribute_sst
(recv
.internal_attributes
, mproperty
.absolute_offset
)
262 # Otherwise, read the attribute value with perfect hashing
263 var id
= mproperty
.intro_mclassdef
.mclass
.vtable
.id
265 i
= read_attribute_ph
(recv
.internal_attributes
, recv
.vtable
.internal_vtable
,
266 recv
.vtable
.mask
, id
, mproperty
.offset
)
269 # If we get a `MInit` value, throw an error
270 if i
== initialization_value
then
271 fatal
("Uninitialized attribute {mproperty.name}")
278 # Return the attribute value in `instance` with a sequence of perfect_hashing
279 # * `instance` is the attributes array of the receiver
280 # * `vtable` is the pointer to the virtual table of the class (of the receiver)
281 # * `mask` is the perfect hashing mask of the class
282 # * `id` is the identifier of the class
283 # * `offset` is the relative offset of this attribute
284 private fun read_attribute_ph
(instance
: Pointer, vtable
: Pointer, mask
: Int, id
: Int, offset
: Int): Instance `{
285 // Perfect hashing position
287 long unsigned int *pointer = (long unsigned int*)(((long int *)vtable)[-hv]);
289 // pointer+1 is the position where the delta of the class is
290 int absolute_offset = *(pointer + 1);
292 Instance res = ((Instance *)instance)[absolute_offset + offset];
297 # Return the attribute value in `instance` with a direct access (SST)
298 # * `instance` is the attributes array of the receiver
299 # * `offset` is the absolute offset of this attribute
300 private fun read_attribute_sst
(instance
: Pointer, offset
: Int): Instance `{
301 /* We can make a direct access to the attribute value
302 because this attribute is always at the same position
303 for the class of this receiver */
304 Instance res = ((Instance *)instance)[offset];
309 # Replace in `recv` the value of the attribute `mproperty` by `value`
310 redef fun write_attribute
(mproperty
: MAttribute, recv
: Instance, value
: Instance)
312 assert recv
isa MutableInstance
314 # Replace the old value of mproperty in recv
315 if mproperty
.intro_mclassdef
.mclass
.positions_attributes
[recv
.mtype
.as(MClassType).mclass
] != -1 then
316 # if this attribute class has an unique position for this receiver, then use direct access
317 write_attribute_sst
(recv
.internal_attributes
, mproperty
.absolute_offset
, value
)
319 # Otherwise, use perfect hashing to replace the old value
320 var id
= mproperty
.intro_mclassdef
.mclass
.vtable
.id
322 write_attribute_ph
(recv
.internal_attributes
, recv
.vtable
.internal_vtable
,
323 recv
.vtable
.mask
, id
, mproperty
.offset
, value
)
327 # Replace the value of an attribute in an instance
328 # * `instance` is the attributes array of the receiver
329 # * `vtable` is the pointer to the virtual table of the class (of the receiver)
330 # * `mask` is the perfect hashing mask of the class
331 # * `id` is the identifier of the class
332 # * `offset` is the relative offset of this attribute
333 # * `value` is the new value for this attribute
334 private fun write_attribute_ph
(instance
: Pointer, vtable
: Pointer, mask
: Int, id
: Int, offset
: Int, value
: Instance) `{
335 // Perfect hashing position
337 long unsigned int *pointer = (long unsigned int*)(((long int *)vtable)[-hv]);
339 // pointer+1 is the position where the delta of the class is
340 int absolute_offset = *(pointer + 1);
342 ((Instance *)instance)[absolute_offset + offset] = value;
343 Instance_incr_ref(value);
346 # Replace the value of an attribute in an instance with direct access
347 # * `instance` is the attributes array of the receiver
348 # * `offset` is the absolute offset of this attribute
349 # * `value` is the new value for this attribute
350 private fun write_attribute_sst
(instance
: Pointer, offset
: Int, value
: Instance) `{
351 // Direct access to the position with the absolute offset
352 ((Instance *)instance)[offset] = value;
353 Instance_incr_ref(value);
356 # Is the attribute `mproperty` initialized in the instance `recv`?
357 redef fun isset_attribute
(mproperty
: MAttribute, recv
: Instance): Bool
359 assert recv
isa MutableInstance
361 # Read the attribute value with internal perfect hashing read
362 # because we do not want to throw an error if the value is `initialization_value`
363 var id
= mproperty
.intro_mclassdef
.mclass
.vtable
.id
365 var i
= read_attribute_ph
(recv
.internal_attributes
, recv
.vtable
.internal_vtable
,
366 recv
.vtable
.mask
, id
, mproperty
.offset
)
368 return i
!= initialization_value
373 # A reference to the virtual table of this class
374 var vtable
: nullable VTable
376 # True when the class is effectively loaded by the vm, false otherwise
377 var loaded
: Bool = false
379 # Color for Cohen subtyping test : the absolute position of the id
380 # of this class in virtual tables
383 # For each loaded subclass, keep the position of the group of attributes
384 # introduced by self class in the object
385 var positions_attributes
: HashMap[MClass, Int] = new HashMap[MClass, Int]
387 # For each loaded subclass, keep the position of the group of methods
388 # introduced by self class in the vtable
389 var positions_methods
: HashMap[MClass, Int] = new HashMap[MClass, Int]
391 # The `MAttribute` this class introduced
392 var intro_mattributes
= new Array[MAttribute]
394 # The `MMethod` this class introduced
395 var intro_mmethods
= new Array[MMethod]
397 # All `MAttribute` this class contains
398 var mattributes
= new Array[MAttribute]
400 # All `MMethod` this class contains
401 var mmethods
= new Array[MMethod]
403 # Allocates a VTable for this class and gives it an id
404 private fun make_vt
(v
: VirtualMachine)
406 if loaded
then return
408 # `superclasses` contains the order of superclasses for virtual tables
409 var superclasses
= superclasses_ordering
(v
)
410 superclasses
.remove
(self)
412 # Make_vt for super-classes
413 var ids
= new Array[Int]
414 var nb_methods
= new Array[Int]
415 var nb_attributes
= new Array[Int]
417 # Absolute offset of attribute from the beginning of the attributes table
418 var offset_attributes
= 0
420 # Absolute offset of method from the beginning of the methods table,
421 # is initialize to 3 because the first position is empty in the virtual table
422 # and the second and third are respectively class id and delta
423 var offset_methods
= 3
425 # The previous element in `superclasses`
426 var previous_parent
: nullable MClass = null
427 if superclasses
.length
> 0 then previous_parent
= superclasses
[0]
428 for parent
in superclasses
do
429 if not parent
.loaded
then parent
.make_vt
(v
)
431 # Get the number of introduced methods and attributes for this class
432 var methods
= parent
.intro_mmethods
.length
433 var attributes
= parent
.intro_mattributes
.length
435 # Updates `mmethods` and `mattributes`
436 mmethods
.add_all
(parent
.intro_mmethods
)
437 mattributes
.add_all
(parent
.intro_mattributes
)
439 ids
.push
(parent
.vtable
.id
)
440 nb_methods
.push
(methods
)
441 nb_attributes
.push
(attributes
)
443 # Update `positions_attributes` and `positions_methods` in `parent`.
444 # If the position is invariant for this parent, store this position
445 # else store a special value (-1)
449 if previous_parent
.as(not null).positions_attributes
[parent
] == offset_attributes
then pos_attr
= offset_attributes
450 if previous_parent
.as(not null).positions_methods
[parent
] == offset_methods
then pos_meth
= offset_methods
452 parent
.update_positions
(pos_attr
, pos_meth
, self)
454 offset_attributes
+= attributes
455 offset_methods
+= methods
456 offset_methods
+= 2 # Because each block starts with an id and the delta
459 # When all super-classes have their identifiers and vtables, allocate current one
460 allocate_vtable
(v
, ids
, nb_methods
, nb_attributes
, offset_attributes
, offset_methods
)
463 # Set the absolute position of the identifier of this class in the virtual table
464 color
= offset_methods
- 2
466 # The virtual table now needs to be filled with pointer to methods
467 superclasses
.add
(self)
468 for cl
in superclasses
do
469 fill_vtable
(v
, vtable
.as(not null), cl
)
473 # Allocate a single vtable
474 # * `ids : Array of superclasses identifiers
475 # * `nb_methods : Array which contain the number of introduced methods for each class in ids
476 # * `nb_attributes : Array which contain the number of introduced attributes for each class in ids
477 # * `offset_attributes : Offset from the beginning of the table of the group of attributes
478 # * `offset_methods : Offset from the beginning of the table of the group of methods
479 private fun allocate_vtable
(v
: VirtualMachine, ids
: Array[Int], nb_methods
: Array[Int], nb_attributes
: Array[Int],
480 offset_attributes
: Int, offset_methods
: Int)
483 var idc
= new Array[Int]
485 vtable
.mask
= v
.ph
.pnand
(ids
, 1, idc
) - 1
487 vtable
.classname
= name
489 # Add current id to Array of super-ids
490 var ids_total
= new Array[Int]
491 ids_total
.add_all
(ids
)
492 ids_total
.push
(vtable
.id
)
494 var nb_methods_total
= new Array[Int]
495 var nb_attributes_total
= new Array[Int]
498 var nb_introduced_attributes
= 0
500 # Fixing offsets for self attributes and methods
501 var relative_offset_attr
= 0
502 var relative_offset_meth
= 0
504 # Update `intro_mmethods` and `intro_mattributes`
505 # For each MClassdef this MClass has
506 for classdef
in mclassdefs
do
507 # For each property this MClassdef introduce
508 for p
in classdef
.intro_mproperties
do
509 # Collect properties and fixing offsets
510 if p
isa MMethod then
512 p
.offset
= relative_offset_meth
513 p
.absolute_offset
= offset_methods
+ relative_offset_meth
514 relative_offset_meth
+= 1
516 intro_mmethods
.add
(p
)
518 if p
isa MAttribute then
519 nb_introduced_attributes
+= 1
520 p
.offset
= relative_offset_attr
521 p
.absolute_offset
= offset_attributes
+ relative_offset_attr
522 relative_offset_attr
+= 1
524 intro_mattributes
.add
(p
)
529 # Updates caches with introduced attributes of `self` class
530 mattributes
.add_all
(intro_mattributes
)
531 mmethods
.add_all
(intro_mmethods
)
533 nb_methods_total
.add_all
(nb_methods
)
534 nb_methods_total
.push
(self_methods
)
536 nb_attributes_total
.add_all
(nb_attributes
)
537 nb_attributes_total
.push
(nb_introduced_attributes
)
539 # Save the offsets of self class
540 update_positions
(offset_attributes
, offset_methods
, self)
542 # Since we have the number of attributes for each class, calculate the delta
543 var deltas
= calculate_delta
(nb_attributes_total
)
544 vtable
.internal_vtable
= v
.memory_manager
.init_vtable
(ids_total
, nb_methods_total
, deltas
, vtable
.mask
)
547 # Fill the vtable with methods of `self` class
548 # * `v` : Current instance of the VirtualMachine
549 # * `table` : the table of self class, will be filled with its methods
550 private fun fill_vtable
(v
:VirtualMachine, table
: VTable, cl
: MClass)
552 var methods
= new Array[MMethodDef]
553 for m
in cl
.intro_mmethods
do
554 # `propdef` is the most specific implementation for this MMethod
555 var propdef
= m
.lookup_first_definition
(v
.mainmodule
, self.intro
.bound_mtype
)
556 methods
.push
(propdef
)
559 # Call a method in C to put propdefs of self methods in the vtables
560 v
.memory_manager
.put_methods
(vtable
.internal_vtable
, vtable
.mask
, cl
.vtable
.id
, methods
)
563 # Computes delta for each class
564 # A delta represents the offset for this group of attributes in the object
565 # *`nb_attributes` : number of attributes for each class (classes are linearized from Object to current)
566 # * return deltas for each class
567 private fun calculate_delta
(nb_attributes
: Array[Int]): Array[Int]
569 var deltas
= new Array[Int]
572 for nb
in nb_attributes
do
580 # Order superclasses of self
581 # Return the order of superclasses in runtime structures of this class
582 private fun superclasses_ordering
(v
: VirtualMachine): Array[MClass]
584 var superclasses
= new Array[MClass]
586 # Add all superclasses of `self`
587 superclasses
.add_all
(self.in_hierarchy
(v
.mainmodule
).greaters
)
589 var res
= new Array[MClass]
590 if superclasses
.length
> 1 then
592 var ordering
= self.dfs
(v
, res
)
596 # There is no super-class, self is Object
601 # A kind of Depth-First-Search for superclasses ordering
602 # *`v` : the current executed instance of VirtualMachine
603 # * `res` : Result Array, ie current superclasses ordering
604 private fun dfs
(v
: VirtualMachine, res
: Array[MClass]): Array[MClass]
606 # Add this class at the beginning
609 var direct_parents
= self.in_hierarchy
(v
.mainmodule
).direct_greaters
.to_a
611 if direct_parents
.length
> 1 then
612 # Prefix represents the class which has the most properties
613 # we try to choose it in first to reduce the number of potential recompilations
616 for cl
in direct_parents
do
617 # If we never have visited this class
618 if not res
.has
(cl
) then
619 var properties_length
= cl
.mmethods
.length
+ cl
.mattributes
.length
620 if properties_length
> max
then
621 max
= properties_length
627 if prefix
!= null then
628 # Add the prefix class ordering at the beginning of our sequence
629 var prefix_res
= new Array[MClass]
630 prefix_res
= prefix
.dfs
(v
, prefix_res
)
632 # Then we recurse on other classes
633 for cl
in direct_parents
do
635 res
= new Array[MClass]
639 if not prefix_res
.has
(cl_res
) then prefix_res
.push
(cl_res
)
648 if direct_parents
.length
> 0 then
649 res
= direct_parents
.first
.dfs
(v
, res
)
653 if not res
.has
(self) then res
.push
(self)
658 # Update positions of the class `cl`
659 # * `attributes_offset`: absolute offset of introduced attributes
660 # * `methods_offset`: absolute offset of introduced methods
661 private fun update_positions
(attributes_offsets
: Int, methods_offset
:Int, cl
: MClass)
663 positions_attributes
[cl
] = attributes_offsets
664 positions_methods
[cl
] = methods_offset
668 redef class MAttribute
669 # Relative offset of this attribute in the runtime instance
670 # (beginning of the block of its introducing class)
673 # Absolute offset of this attribute in the runtime instance (beginning of the attribute table)
674 var absolute_offset
: Int
678 # Relative offset of this method in the virtual table (from the beginning of the block)
681 # Absolute offset of this method in the virtual table (from the beginning of the vtable)
682 var absolute_offset
: Int
685 # Redef MutableInstance to improve implementation of attributes in objects
686 redef class MutableInstance
688 # C-array to store pointers to attributes of this Object
689 var internal_attributes
: Pointer
692 # Redef to associate an `Instance` to its `VTable`
695 # Associate a runtime instance to its virtual table which contains methods, types etc.
696 var vtable
: nullable VTable
699 # Is the type of the initial value inside attributes
703 redef var model
: Model
705 redef fun to_s
do return "InitType"
706 redef fun as_nullable
do return self
707 redef fun need_anchor
do return false
708 redef fun resolve_for
(mtype
, anchor
, mmodule
, cleanup_virtual
) do return self
709 redef fun can_resolve_for
(mtype
, anchor
, mmodule
) do return true
711 redef fun collect_mclassdefs
(mmodule
) do return new HashSet[MClassDef]
713 redef fun collect_mclasses
(mmodule
) do return new HashSet[MClass]
715 redef fun collect_mtypes
(mmodule
) do return new HashSet[MClassType]
718 # A VTable contains the virtual method table for the dispatch
719 # and informations to perform subtyping tests
721 # The mask to perform perfect hashing
722 var mask
: Int is noinit
724 # Unique identifier given by perfect hashing
725 var id
: Int is noinit
727 # Pointer to the c-allocated area, represents the virtual table
728 var internal_vtable
: Pointer is noinit
730 # The short classname of this class
731 var classname
: String is noinit
734 # Handle memory, used for allocate virtual table and associated structures
737 # Allocate and fill a virtual table
738 fun init_vtable
(ids
: Array[Int], nb_methods
: Array[Int], nb_attributes
: Array[Int], mask
: Int): Pointer
740 # Allocate in C current virtual table
741 var res
= intern_init_vtable
(ids
, nb_methods
, nb_attributes
, mask
)
746 # Construct virtual tables with a bi-dimensional layout
747 private fun intern_init_vtable
(ids
: Array[Int], nb_methods
: Array[Int], deltas
: Array[Int], mask
: Int): Pointer
748 import Array[Int].length
, Array[Int].[] `{
750 // Allocate and fill current virtual table
752 int total_size = 0; // total size of this virtual table
753 int nb_classes = Array_of_Int_length(nb_methods);
754 for(i = 0; i<nb_classes; i++) {
755 /* - One for each method of this class
756 * - One for the delta (offset of this group of attributes in objects)
759 total_size += Array_of_Int__index(nb_methods, i);
763 // Add the size of the perfect hashtable (mask +1)
764 // Add one because we start to fill the vtable at position 1 (0 is the init position)
765 total_size += mask+2;
766 long unsigned int* vtable = malloc(sizeof(long unsigned int)*total_size);
768 // Initialisation to the first position of the virtual table (ie : Object)
769 long unsigned int *init = vtable + mask + 2;
770 for(i=0; i<total_size; i++)
771 vtable[i] = (long unsigned int)init;
773 // Set the virtual table to its position 0
774 // ie: after the hashtable
775 vtable = vtable + mask + 1;
777 int current_size = 1;
778 for(i = 0; i < nb_classes; i++) {
780 vtable[hv] contains a pointer to the group of introduced methods
781 For each superclasse we have in virtual table :
782 (id | delta | introduced methods)
784 int hv = mask & Array_of_Int__index(ids, i);
786 vtable[current_size] = Array_of_Int__index(ids, i);
787 vtable[current_size + 1] = Array_of_Int__index(deltas, i);
788 vtable[-hv] = (long unsigned int)&(vtable[current_size]);
791 current_size += Array_of_Int__index(nb_methods, i);
797 # Put implementation of methods of a class in `vtable`
798 # * `vtable` : Pointer to the C-virtual table
799 # * `mask` : perfect-hashing mask of the class corresponding to the vtable
800 # * `id` : id of the target class
801 # * `methods` : array of MMethodDef of the target class
802 fun put_methods
(vtable
: Pointer, mask
: Int, id
: Int, methods
: Array[MMethodDef])
803 import Array[MMethodDef].length
, Array[MMethodDef].[] `{
805 // Get the area to fill with methods by a sequence of perfect hashing
807 long unsigned int *pointer = (long unsigned int*)(((long unsigned int *)vtable)[-hv]);
809 // pointer+2 is the beginning of the area for methods implementation
810 int length = Array_of_MMethodDef_length(methods);
811 long unsigned int *area = (pointer + 2);
814 for(i=0; i<length; i++)
816 MMethodDef method = Array_of_MMethodDef__index(methods, i);
817 area[i] = (long unsigned int)method;
818 MMethodDef_incr_ref(method);