53a99fa9be20c5638636163d12b12dbb006e1b66
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
22 import perfect_hashing
24 redef class ModelBuilder
25 redef fun run_naive_interpreter
(mainmodule
: MModule, arguments
: Array[String])
28 self.toolcontext
.info
("*** NITVM STARTING ***", 1)
30 var interpreter
= new VirtualMachine(self, mainmodule
, arguments
)
31 interpreter
.start
(mainmodule
)
34 self.toolcontext
.info
("*** NITVM STOPPING : {time1-time0} ***", 2)
38 # A virtual machine based on the naive_interpreter
39 class VirtualMachine super NaiveInterpreter
41 # Perfect hashing and perfect numbering
42 var ph
: Perfecthashing = new Perfecthashing
44 # Handles memory allocated in C
45 var memory_manager
: MemoryManager = new MemoryManager
47 # The unique instance of the `MInit` value
48 var initialization_value
: Instance is noinit
52 var init_type
= new MInitType(mainmodule
.model
)
53 initialization_value
= new MutableInstance(init_type
)
57 # Runtime subtyping test
58 redef fun is_subtype
(sub
, sup
: MType): Bool
60 if sub
== sup
then return true
62 var anchor
= self.frame
.arguments
.first
.mtype
.as(MClassType)
64 # `sub` or `sup` are formal or virtual types, resolve them to concrete types
65 if sub
isa MParameterType or sub
isa MVirtualType then
66 sub
= sub
.resolve_for
(anchor
.mclass
.mclass_type
, anchor
, mainmodule
, false)
68 if sup
isa MParameterType or sup
isa MVirtualType then
69 sup
= sup
.resolve_for
(anchor
.mclass
.mclass_type
, anchor
, mainmodule
, false)
72 var sup_accept_null
= false
73 if sup
isa MNullableType then
74 sup_accept_null
= true
76 else if sup
isa MNullType then
77 sup_accept_null
= true
80 # Can `sub` provides null or not?
81 # Thus we can match with `sup_accept_null`
82 # Also discard the nullable marker if it exists
83 if sub
isa MNullableType then
84 if not sup_accept_null
then return false
86 else if sub
isa MNullType then
87 return sup_accept_null
89 # Now the case of direct null and nullable is over
91 if sub
isa MParameterType or sub
isa MVirtualType then
92 sub
= sub
.anchor_to
(mainmodule
, anchor
)
93 # Manage the second layer of null/nullable
94 if sub
isa MNullableType then
95 if not sup_accept_null
then return false
97 else if sub
isa MNullType then
98 return sup_accept_null
102 assert sub
isa MClassType
104 # `sup` accepts only null
105 if sup
isa MNullType then return false
107 assert sup
isa MClassType
109 # `sub` and `sup` can be discovered inside a Generic type during the subtyping test
110 if not sup
.mclass
.loaded
then create_class
(sup
.mclass
)
111 if not sub
.mclass
.loaded
then create_class
(sub
.mclass
)
113 # For now, always use perfect hashing for subtyping test
114 var super_id
= sup
.mclass
.vtable
.id
115 var mask
= sub
.mclass
.vtable
.mask
117 var res
= inter_is_subtype_ph
(super_id
, mask
, sub
.mclass
.vtable
.internal_vtable
)
118 if res
== false then return false
119 # sub and sup can be generic types, each argument of generics has to be tested
121 if not sup
isa MGenericType then return true
122 var sub2
= sub
.supertype_to
(mainmodule
, anchor
, sup
.mclass
)
124 # Test each argument of a generic by recursive calls
125 for i
in [0..sup
.mclass
.arity
[ do
126 var sub_arg
= sub2
.arguments
[i
]
127 var sup_arg
= sup
.arguments
[i
]
128 var res2
= is_subtype
(sub_arg
, sup_arg
)
129 if res2
== false then return false
134 # Subtyping test with perfect hashing
135 private fun inter_is_subtype_ph
(id
: Int, mask
:Int, vtable
: Pointer): Bool `{
136 // hv is the position in hashtable
139 // Follow the pointer to somewhere in the vtable
140 long unsigned int *offset = (long unsigned int*)(((long int *)vtable)[-hv]);
142 // If the pointed value is corresponding to the identifier, the test is true, otherwise false
143 return *offset == id;
146 # Subtyping test with Cohen test (direct access)
147 private fun inter_is_subtype_sst
(id
: Int, position
: Int, vtable
: Pointer): Bool `{
148 // Direct access to the position given in parameter
149 int tableid = (long unsigned int)((long int *)vtable)[position];
151 return id == tableid;
154 # Redef init_instance to simulate the loading of a class
155 redef fun init_instance
(recv
: Instance)
157 if not recv
.mtype
.as(MClassType).mclass
.loaded
then create_class
(recv
.mtype
.as(MClassType).mclass
)
159 recv
.vtable
= recv
.mtype
.as(MClassType).mclass
.vtable
161 assert recv
isa MutableInstance
163 recv
.internal_attributes
= init_internal_attributes
(initialization_value
, recv
.mtype
.as(MClassType).mclass
.all_mattributes
(mainmodule
, none_visibility
).length
)
167 # Associate a `PrimitiveInstance` to its `VTable`
168 redef fun init_instance_primitive
(recv
: Instance)
170 if not recv
.mtype
.as(MClassType).mclass
.loaded
then create_class
(recv
.mtype
.as(MClassType).mclass
)
172 recv
.vtable
= recv
.mtype
.as(MClassType).mclass
.vtable
175 # Create a virtual table for this `MClass` if not already done
176 redef fun get_primitive_class
(name
: String): MClass
180 if not mclass
.loaded
then create_class
(mclass
)
185 # Initialize the internal representation of an object (its attribute values)
186 # `init_instance` is the initial value of attributes
187 private fun init_internal_attributes
(init_instance
: Instance, size
: Int): Pointer
188 import Array[Instance].length
, Array[Instance].[] `{
190 Instance* attributes = malloc(sizeof(Instance) * size);
193 for(i=0; i<size; i++)
194 attributes[i] = init_instance;
196 Instance_incr_ref(init_instance);
200 # Creates the runtime structures for this class
201 fun create_class
(mclass
: MClass) do mclass
.make_vt
(self)
203 # Execute `mproperty` for a `args` (where `args[0]` is the receiver).
204 redef fun send
(mproperty
: MMethod, args
: Array[Instance]): nullable Instance
206 var recv
= args
.first
207 var mtype
= recv
.mtype
208 var ret
= send_commons
(mproperty
, args
, mtype
)
209 if ret
!= null then return ret
211 var propdef
= method_dispatch
(mproperty
, recv
.vtable
.as(not null), recv
)
213 return self.call
(propdef
, args
)
216 # Method dispatch, for a given global method `mproperty`
217 # returns the most specific local method in the class corresponding to `vtable`
218 private fun method_dispatch
(mproperty
: MMethod, vtable
: VTable, recv
: Instance): MMethodDef
220 if mproperty
.intro_mclassdef
.mclass
.positions_methods
[recv
.mtype
.as(MClassType).mclass
] != -1 then
221 return method_dispatch_sst
(vtable
.internal_vtable
, mproperty
.absolute_offset
)
223 return method_dispatch_ph
(vtable
.internal_vtable
, vtable
.mask
,
224 mproperty
.intro_mclassdef
.mclass
.vtable
.id
, mproperty
.offset
)
228 # Execute a method dispatch with perfect hashing
229 private fun method_dispatch_ph
(vtable
: Pointer, mask
: Int, id
: Int, offset
: Int): MMethodDef `{
230 // Perfect hashing position
232 long unsigned int *pointer = (long unsigned int*)(((long int *)vtable)[-hv]);
234 // pointer+2 is the position where methods are
235 // Add the offset of property and get the method implementation
236 MMethodDef propdef = (MMethodDef)*(pointer + 2 + offset);
241 # Execute a method dispatch with direct access and return the appropriate `MMethodDef`
242 # `vtable` : Pointer to the internal pointer of the class
243 # `absolute_offset` : Absolute offset from the beginning of the virtual table
244 private fun method_dispatch_sst
(vtable
: Pointer, absolute_offset
: Int): MMethodDef `{
245 // pointer+2 is the position where methods are
246 // Add the offset of property and get the method implementation
247 MMethodDef propdef = (MMethodDef)((long int *)vtable)[absolute_offset];
252 # Return the value of the attribute `mproperty` for the object `recv`
253 redef fun read_attribute
(mproperty
: MAttribute, recv
: Instance): Instance
255 assert recv
isa MutableInstance
259 if mproperty
.intro_mclassdef
.mclass
.positions_attributes
[recv
.mtype
.as(MClassType).mclass
] != -1 then
260 # if this attribute class has an unique position for this receiver, then use direct access
261 i
= read_attribute_sst
(recv
.internal_attributes
, mproperty
.absolute_offset
)
263 # Otherwise, read the attribute value with perfect hashing
264 var id
= mproperty
.intro_mclassdef
.mclass
.vtable
.id
266 i
= read_attribute_ph
(recv
.internal_attributes
, recv
.vtable
.internal_vtable
,
267 recv
.vtable
.mask
, id
, mproperty
.offset
)
270 # If we get a `MInit` value, throw an error
271 if i
== initialization_value
then
272 fatal
("Uninitialized attribute {mproperty.name}")
279 # Return the attribute value in `instance` with a sequence of perfect_hashing
280 # * `instance` is the attributes array of the receiver
281 # * `vtable` is the pointer to the virtual table of the class (of the receiver)
282 # * `mask` is the perfect hashing mask of the class
283 # * `id` is the identifier of the class
284 # * `offset` is the relative offset of this attribute
285 private fun read_attribute_ph
(instance
: Pointer, vtable
: Pointer, mask
: Int, id
: Int, offset
: Int): Instance `{
286 // Perfect hashing position
288 long unsigned int *pointer = (long unsigned int*)(((long int *)vtable)[-hv]);
290 // pointer+1 is the position where the delta of the class is
291 int absolute_offset = *(pointer + 1);
293 Instance res = ((Instance *)instance)[absolute_offset + offset];
298 # Return the attribute value in `instance` with a direct access (SST)
299 # * `instance` is the attributes array of the receiver
300 # * `offset` is the absolute offset of this attribute
301 private fun read_attribute_sst
(instance
: Pointer, offset
: Int): Instance `{
302 /* We can make a direct access to the attribute value
303 because this attribute is always at the same position
304 for the class of this receiver */
305 Instance res = ((Instance *)instance)[offset];
310 # Replace in `recv` the value of the attribute `mproperty` by `value`
311 redef fun write_attribute
(mproperty
: MAttribute, recv
: Instance, value
: Instance)
313 assert recv
isa MutableInstance
315 # Replace the old value of mproperty in recv
316 if mproperty
.intro_mclassdef
.mclass
.positions_attributes
[recv
.mtype
.as(MClassType).mclass
] != -1 then
317 # if this attribute class has an unique position for this receiver, then use direct access
318 write_attribute_sst
(recv
.internal_attributes
, mproperty
.absolute_offset
, value
)
320 # Otherwise, use perfect hashing to replace the old value
321 var id
= mproperty
.intro_mclassdef
.mclass
.vtable
.id
323 write_attribute_ph
(recv
.internal_attributes
, recv
.vtable
.internal_vtable
,
324 recv
.vtable
.mask
, id
, mproperty
.offset
, value
)
328 # Replace the value of an attribute in an instance
329 # * `instance` is the attributes array of the receiver
330 # * `vtable` is the pointer to the virtual table of the class (of the receiver)
331 # * `mask` is the perfect hashing mask of the class
332 # * `id` is the identifier of the class
333 # * `offset` is the relative offset of this attribute
334 # * `value` is the new value for this attribute
335 private fun write_attribute_ph
(instance
: Pointer, vtable
: Pointer, mask
: Int, id
: Int, offset
: Int, value
: Instance) `{
336 // Perfect hashing position
338 long unsigned int *pointer = (long unsigned int*)(((long int *)vtable)[-hv]);
340 // pointer+1 is the position where the delta of the class is
341 int absolute_offset = *(pointer + 1);
343 ((Instance *)instance)[absolute_offset + offset] = value;
344 Instance_incr_ref(value);
347 # Replace the value of an attribute in an instance with direct access
348 # * `instance` is the attributes array of the receiver
349 # * `offset` is the absolute offset of this attribute
350 # * `value` is the new value for this attribute
351 private fun write_attribute_sst
(instance
: Pointer, offset
: Int, value
: Instance) `{
352 // Direct access to the position with the absolute offset
353 ((Instance *)instance)[offset] = value;
354 Instance_incr_ref(value);
357 # Is the attribute `mproperty` initialized in the instance `recv`?
358 redef fun isset_attribute
(mproperty
: MAttribute, recv
: Instance): Bool
360 assert recv
isa MutableInstance
362 # Read the attribute value with internal perfect hashing read
363 # because we do not want to throw an error if the value is `initialization_value`
364 var id
= mproperty
.intro_mclassdef
.mclass
.vtable
.id
366 var i
= read_attribute_ph
(recv
.internal_attributes
, recv
.vtable
.internal_vtable
,
367 recv
.vtable
.mask
, id
, mproperty
.offset
)
369 return i
!= initialization_value
374 # A reference to the virtual table of this class
375 var vtable
: nullable VTable
377 # True when the class is effectively loaded by the vm, false otherwise
378 var loaded
: Bool = false
380 # Color for Cohen subtyping test : the absolute position of the id
381 # of this class in virtual tables
384 # For each loaded subclass, keep the position of the group of attributes
385 # introduced by self class in the object
386 var positions_attributes
: HashMap[MClass, Int] = new HashMap[MClass, Int]
388 # For each loaded subclass, keep the position of the group of methods
389 # introduced by self class in the vtable
390 var positions_methods
: HashMap[MClass, Int] = new HashMap[MClass, Int]
392 # Allocates a VTable for this class and gives it an id
393 private fun make_vt
(v
: VirtualMachine)
395 if loaded
then return
397 # `superclasses` contains the order of superclasses for virtual tables
398 var superclasses
= superclasses_ordering
(v
)
399 superclasses
.remove
(self)
401 # Make_vt for super-classes
402 var ids
= new Array[Int]
403 var nb_methods
= new Array[Int]
404 var nb_attributes
= new Array[Int]
406 # Absolute offset of attribute from the beginning of the attributes table
407 var offset_attributes
= 0
409 # Absolute offset of method from the beginning of the methods table,
410 # is initialize to 3 because the first position is empty in the virtual table
411 # and the second and third are respectively class id and delta
412 var offset_methods
= 3
414 # The previous element in `superclasses`
415 var previous_parent
: nullable MClass = null
416 if superclasses
.length
> 0 then previous_parent
= superclasses
[0]
417 for parent
in superclasses
do
418 if not parent
.loaded
then parent
.make_vt
(v
)
420 # Get the number of introduced methods and attributes for this class
424 for p
in parent
.intro_mproperties
(none_visibility
) do
425 if p
isa MMethod then methods
+= 1
426 if p
isa MAttribute then attributes
+= 1
429 ids
.push
(parent
.vtable
.id
)
430 nb_methods
.push
(methods
)
431 nb_attributes
.push
(attributes
)
433 # Update `positions_attributes` and `positions_methods` in `parent`.
434 # If the position is invariant for this parent, store this position
435 # else store a special value (-1)
439 if previous_parent
.as(not null).positions_attributes
[parent
] == offset_attributes
then pos_attr
= offset_attributes
440 if previous_parent
.as(not null).positions_methods
[parent
] == offset_methods
then pos_meth
= offset_methods
442 parent
.update_positions
(pos_attr
, pos_meth
, self)
444 offset_attributes
+= attributes
445 offset_methods
+= methods
446 offset_methods
+= 2 # Because each block starts with an id and the delta
449 # When all super-classes have their identifiers and vtables, allocate current one
450 allocate_vtable
(v
, ids
, nb_methods
, nb_attributes
, offset_attributes
, offset_methods
)
453 # Set the absolute position of the identifier of this class in the virtual table
454 color
= offset_methods
- 2
456 # The virtual table now needs to be filled with pointer to methods
457 superclasses
.add
(self)
458 for cl
in superclasses
do
459 fill_vtable
(v
, vtable
.as(not null), cl
)
463 # Allocate a single vtable
464 # * `ids : Array of superclasses identifiers
465 # * `nb_methods : Array which contain the number of introduced methods for each class in ids
466 # * `nb_attributes : Array which contain the number of introduced attributes for each class in ids
467 # * `offset_attributes : Offset from the beginning of the table of the group of attributes
468 # * `offset_methods : Offset from the beginning of the table of the group of methods
469 private fun allocate_vtable
(v
: VirtualMachine, ids
: Array[Int], nb_methods
: Array[Int], nb_attributes
: Array[Int],
470 offset_attributes
: Int, offset_methods
: Int)
473 var idc
= new Array[Int]
475 vtable
.mask
= v
.ph
.pnand
(ids
, 1, idc
) - 1
477 vtable
.classname
= name
479 # Add current id to Array of super-ids
480 var ids_total
= new Array[Int]
481 ids_total
.add_all
(ids
)
482 ids_total
.push
(vtable
.id
)
484 var nb_methods_total
= new Array[Int]
485 var nb_attributes_total
= new Array[Int]
488 var nb_introduced_attributes
= 0
490 # Fixing offsets for self attributes and methods
491 var relative_offset_attr
= 0
492 var relative_offset_meth
= 0
493 for p
in intro_mproperties
(none_visibility
) do
494 if p
isa MMethod then
496 p
.offset
= relative_offset_meth
497 p
.absolute_offset
= offset_methods
+ relative_offset_meth
498 relative_offset_meth
+= 1
500 if p
isa MAttribute then
501 nb_introduced_attributes
+= 1
502 p
.offset
= relative_offset_attr
503 p
.absolute_offset
= offset_attributes
+ relative_offset_attr
504 relative_offset_attr
+= 1
508 nb_methods_total
.add_all
(nb_methods
)
509 nb_methods_total
.push
(self_methods
)
511 nb_attributes_total
.add_all
(nb_attributes
)
512 nb_attributes_total
.push
(nb_introduced_attributes
)
514 # Save the offsets of self class
515 update_positions
(offset_attributes
, offset_methods
, self)
517 # Since we have the number of attributes for each class, calculate the delta
518 var deltas
= calculate_delta
(nb_attributes_total
)
519 vtable
.internal_vtable
= v
.memory_manager
.init_vtable
(ids_total
, nb_methods_total
, deltas
, vtable
.mask
)
522 # Fill the vtable with methods of `self` class
523 # * `v` : Current instance of the VirtualMachine
524 # * `table` : the table of self class, will be filled with its methods
525 private fun fill_vtable
(v
:VirtualMachine, table
: VTable, cl
: MClass)
527 var methods
= new Array[MMethodDef]
528 for m
in cl
.intro_mproperties
(none_visibility
) do
529 if m
isa MMethod then
530 # `propdef` is the most specific implementation for this MMethod
531 var propdef
= m
.lookup_first_definition
(v
.mainmodule
, self.intro
.bound_mtype
)
532 methods
.push
(propdef
)
536 # Call a method in C to put propdefs of self methods in the vtables
537 v
.memory_manager
.put_methods
(vtable
.internal_vtable
, vtable
.mask
, cl
.vtable
.id
, methods
)
540 # Computes delta for each class
541 # A delta represents the offset for this group of attributes in the object
542 # *`nb_attributes` : number of attributes for each class (classes are linearized from Object to current)
543 # * return deltas for each class
544 private fun calculate_delta
(nb_attributes
: Array[Int]): Array[Int]
546 var deltas
= new Array[Int]
549 for nb
in nb_attributes
do
557 # Order superclasses of self
558 # Return the order of superclasses in runtime structures of this class
559 private fun superclasses_ordering
(v
: VirtualMachine): Array[MClass]
561 var superclasses
= new Array[MClass]
563 # Add all superclasses of `self`
564 superclasses
.add_all
(self.in_hierarchy
(v
.mainmodule
).greaters
)
566 var res
= new Array[MClass]
567 if superclasses
.length
> 1 then
569 var ordering
= self.dfs
(v
, res
)
573 # There is no super-class, self is Object
578 # A kind of Depth-First-Search for superclasses ordering
579 # *`v` : the current executed instance of VirtualMachine
580 # * `res` : Result Array, ie current superclasses ordering
581 private fun dfs
(v
: VirtualMachine, res
: Array[MClass]): Array[MClass]
583 # Add this class at the beginning
586 var direct_parents
= self.in_hierarchy
(v
.mainmodule
).direct_greaters
.to_a
588 if direct_parents
.length
> 1 then
589 # Prefix represents the class which has the most properties
590 # we try to choose it in first to reduce the number of potential recompilations
593 for cl
in direct_parents
do
594 # If we never have visited this class
595 if not res
.has
(cl
) then
596 var properties_length
= cl
.all_mproperties
(v
.mainmodule
, none_visibility
).length
597 if properties_length
> max
then
598 max
= properties_length
604 if prefix
!= null then
605 # Add the prefix class ordering at the beginning of our sequence
606 var prefix_res
= new Array[MClass]
607 prefix_res
= prefix
.dfs
(v
, prefix_res
)
609 # Then we recurse on other classes
610 for cl
in direct_parents
do
612 res
= new Array[MClass]
616 if not prefix_res
.has
(cl_res
) then prefix_res
.push
(cl_res
)
625 if direct_parents
.length
> 0 then
626 res
= direct_parents
.first
.dfs
(v
, res
)
630 if not res
.has
(self) then res
.push
(self)
635 # Update positions of the class `cl`
636 # * `attributes_offset`: absolute offset of introduced attributes
637 # * `methods_offset`: absolute offset of introduced methods
638 private fun update_positions
(attributes_offsets
: Int, methods_offset
:Int, cl
: MClass)
640 positions_attributes
[cl
] = attributes_offsets
641 positions_methods
[cl
] = methods_offset
645 redef class MAttribute
646 # Relative offset of this attribute in the runtime instance
647 # (beginning of the block of its introducing class)
650 # Absolute offset of this attribute in the runtime instance (beginning of the attribute table)
651 var absolute_offset
: Int
655 # Relative offset of this method in the virtual table (from the beginning of the block)
658 # Absolute offset of this method in the virtual table (from the beginning of the vtable)
659 var absolute_offset
: Int
662 # Redef MutableInstance to improve implementation of attributes in objects
663 redef class MutableInstance
665 # C-array to store pointers to attributes of this Object
666 var internal_attributes
: Pointer
669 # Redef to associate an `Instance` to its `VTable`
672 # Associate a runtime instance to its virtual table which contains methods, types etc.
673 var vtable
: nullable VTable
676 # Is the type of the initial value inside attributes
680 redef var model
: Model
682 redef fun to_s
do return "InitType"
683 redef fun as_nullable
do return self
684 redef fun need_anchor
do return false
685 redef fun resolve_for
(mtype
, anchor
, mmodule
, cleanup_virtual
) do return self
686 redef fun can_resolve_for
(mtype
, anchor
, mmodule
) do return true
688 redef fun collect_mclassdefs
(mmodule
) do return new HashSet[MClassDef]
690 redef fun collect_mclasses
(mmodule
) do return new HashSet[MClass]
692 redef fun collect_mtypes
(mmodule
) do return new HashSet[MClassType]
695 # A VTable contains the virtual method table for the dispatch
696 # and informations to perform subtyping tests
698 # The mask to perform perfect hashing
699 var mask
: Int is noinit
701 # Unique identifier given by perfect hashing
702 var id
: Int is noinit
704 # Pointer to the c-allocated area, represents the virtual table
705 var internal_vtable
: Pointer is noinit
707 # The short classname of this class
708 var classname
: String is noinit
711 # Handle memory, used for allocate virtual table and associated structures
714 # Allocate and fill a virtual table
715 fun init_vtable
(ids
: Array[Int], nb_methods
: Array[Int], nb_attributes
: Array[Int], mask
: Int): Pointer
717 # Allocate in C current virtual table
718 var res
= intern_init_vtable
(ids
, nb_methods
, nb_attributes
, mask
)
723 # Construct virtual tables with a bi-dimensional layout
724 private fun intern_init_vtable
(ids
: Array[Int], nb_methods
: Array[Int], deltas
: Array[Int], mask
: Int): Pointer
725 import Array[Int].length
, Array[Int].[] `{
727 // Allocate and fill current virtual table
729 int total_size = 0; // total size of this virtual table
730 int nb_classes = Array_of_Int_length(nb_methods);
731 for(i = 0; i<nb_classes; i++) {
732 /* - One for each method of this class
733 * - One for the delta (offset of this group of attributes in objects)
736 total_size += Array_of_Int__index(nb_methods, i);
740 // Add the size of the perfect hashtable (mask +1)
741 // Add one because we start to fill the vtable at position 1 (0 is the init position)
742 total_size += mask+2;
743 long unsigned int* vtable = malloc(sizeof(long unsigned int)*total_size);
745 // Initialisation to the first position of the virtual table (ie : Object)
746 long unsigned int *init = vtable + mask + 2;
747 for(i=0; i<total_size; i++)
748 vtable[i] = (long unsigned int)init;
750 // Set the virtual table to its position 0
751 // ie: after the hashtable
752 vtable = vtable + mask + 1;
754 int current_size = 1;
755 for(i = 0; i < nb_classes; i++) {
757 vtable[hv] contains a pointer to the group of introduced methods
758 For each superclasse we have in virtual table :
759 (id | delta | introduced methods)
761 int hv = mask & Array_of_Int__index(ids, i);
763 vtable[current_size] = Array_of_Int__index(ids, i);
764 vtable[current_size + 1] = Array_of_Int__index(deltas, i);
765 vtable[-hv] = (long unsigned int)&(vtable[current_size]);
768 current_size += Array_of_Int__index(nb_methods, i);
774 # Put implementation of methods of a class in `vtable`
775 # * `vtable` : Pointer to the C-virtual table
776 # * `mask` : perfect-hashing mask of the class corresponding to the vtable
777 # * `id` : id of the target class
778 # * `methods` : array of MMethodDef of the target class
779 fun put_methods
(vtable
: Pointer, mask
: Int, id
: Int, methods
: Array[MMethodDef])
780 import Array[MMethodDef].length
, Array[MMethodDef].[] `{
782 // Get the area to fill with methods by a sequence of perfect hashing
784 long unsigned int *pointer = (long unsigned int*)(((long unsigned int *)vtable)[-hv]);
786 // pointer+2 is the beginning of the area for methods implementation
787 int length = Array_of_MMethodDef_length(methods);
788 long unsigned int *area = (pointer + 2);
791 for(i=0; i<length; i++)
793 MMethodDef method = Array_of_MMethodDef__index(methods, i);
794 area[i] = (long unsigned int)method;
795 MMethodDef_incr_ref(method);