fd271177a57a4762545bb5c91f8caf28c8cb7761
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 intrude 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 init_naive_interpreter
(interpreter
, 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 and garbage collection
45 var memory_manager
: MemoryManager = new MemoryManager
47 # The unique instance of the `MInit` value
48 var initialization_value
: Instance
50 init(modelbuilder
: ModelBuilder, mainmodule
: MModule, arguments
: Array[String])
53 var init_type
= new MInitType(mainmodule
.model
)
54 initialization_value
= new MutableInstance(init_type
)
57 # Subtyping test for the virtual machine
58 redef fun is_subtype
(sub
, sup
: MType): Bool
60 var anchor
= self.frame
.arguments
.first
.mtype
.as(MClassType)
61 var sup_accept_null
= false
62 if sup
isa MNullableType then
63 sup_accept_null
= true
65 else if sup
isa MNullType then
66 sup_accept_null
= true
69 # Can `sub` provides null or not?
70 # Thus we can match with `sup_accept_null`
71 # Also discard the nullable marker if it exists
72 if sub
isa MNullableType then
73 if not sup_accept_null
then return false
75 else if sub
isa MNullType then
76 return sup_accept_null
78 # Now the case of direct null and nullable is over
80 # An unfixed formal type can only accept itself
81 if sup
isa MParameterType or sup
isa MVirtualType then
85 if sub
isa MParameterType or sub
isa MVirtualType then
86 sub
= sub
.anchor_to
(mainmodule
, anchor
)
87 # Manage the second layer of null/nullable
88 if sub
isa MNullableType then
89 if not sup_accept_null
then return false
91 else if sub
isa MNullType then
92 return sup_accept_null
96 assert sub
isa MClassType
98 # `sup` accepts only null
99 if sup
isa MNullType then return false
101 assert sup
isa MClassType
103 # Create the sup vtable if not create
104 if not sup
.mclass
.loaded
then create_class
(sup
.mclass
)
106 # Sub can be discovered inside a Generic type during the subtyping test
107 if not sub
.mclass
.loaded
then create_class
(sub
.mclass
)
109 if anchor
== null then anchor
= sub
110 if sup
isa MGenericType then
111 var sub2
= sub
.supertype_to
(mainmodule
, anchor
, sup
.mclass
)
112 assert sub2
.mclass
== sup
.mclass
114 for i
in [0..sup
.mclass
.arity
[ do
115 var sub_arg
= sub2
.arguments
[i
]
116 var sup_arg
= sup
.arguments
[i
]
117 var res
= is_subtype
(sub_arg
, sup_arg
)
119 if res
== false then return false
124 var super_id
= sup
.mclass
.vtable
.id
125 var mask
= sub
.mclass
.vtable
.mask
127 return inter_is_subtype
(super_id
, mask
, sub
.mclass
.vtable
.internal_vtable
)
130 # Subtyping test with perfect hashing
131 private fun inter_is_subtype
(id
: Int, mask
:Int, vtable
: Pointer): Bool `{
132 // hv is the position in hashtable
135 // Follow the pointer to somewhere in the vtable
136 long unsigned int *offset = (long unsigned int*)(((long int *)vtable)[-hv]);
138 // If the pointed value is corresponding to the identifier, the test is true, otherwise false
139 return *offset == id;
142 # Redef init_instance to simulate the loading of a class
143 redef fun init_instance
(recv
: Instance)
145 if not recv
.mtype
.as(MClassType).mclass
.loaded
then create_class
(recv
.mtype
.as(MClassType).mclass
)
147 recv
.vtable
= recv
.mtype
.as(MClassType).mclass
.vtable
149 assert(recv
isa MutableInstance)
151 recv
.internal_attributes
= init_internal_attributes
(null_instance
, recv
.mtype
.as(MClassType).mclass
.all_mattributes
(mainmodule
, none_visibility
).length
)
155 # Initialize the internal representation of an object (its attribute values)
156 private fun init_internal_attributes
(null_instance
: Instance, size
: Int): Pointer
157 import Array[Instance].length
, Array[Instance].[] `{
159 Instance* attributes = malloc(sizeof(Instance) * size);
162 for(i=0; i<size; i++)
163 attributes[i] = null_instance;
165 Instance_incr_ref(null_instance);
169 # Creates the runtime structures for this class
170 fun create_class
(mclass
: MClass) do mclass
.make_vt
(self)
172 # Return the value of the attribute `mproperty` for the object `recv`
173 redef fun read_attribute
(mproperty
: MAttribute, recv
: Instance): Instance
175 assert recv
isa MutableInstance
177 # Read the attribute value with perfect hashing
178 var id
= mproperty
.intro_mclassdef
.mclass
.vtable
.id
180 var i
= read_attribute_ph
(recv
.internal_attributes
, recv
.vtable
.internal_vtable
,
181 recv
.vtable
.mask
, id
, mproperty
.offset
)
186 # Return the attribute value in `instance` with a sequence of perfect_hashing
187 # `instance` is the attributes array of the receiver
188 # `vtable` is the pointer to the virtual table of the class (of the receiver)
189 # `mask` is the perfect hashing mask of the class
190 # `id` is the identifier of the class
191 # `offset` is the relative offset of this attribute
192 private fun read_attribute_ph
(instance
: Pointer, vtable
: Pointer, mask
: Int, id
: Int, offset
: Int): Instance `{
193 // Perfect hashing position
195 long unsigned int *pointer = (long unsigned int*)(((long int *)vtable)[-hv]);
197 // pointer+1 is the position where the delta of the class is
198 int absolute_offset = *(pointer + 1);
200 Instance res = ((Instance *)instance)[absolute_offset + offset];
205 # Replace in `recv` the value of the attribute `mproperty` by `value`
206 redef fun write_attribute
(mproperty
: MAttribute, recv
: Instance, value
: Instance)
208 assert recv
isa MutableInstance
210 var id
= mproperty
.intro_mclassdef
.mclass
.vtable
.id
212 # Replace the old value of mproperty in recv
213 write_attribute_ph
(recv
.internal_attributes
, recv
.vtable
.internal_vtable
,
214 recv
.vtable
.mask
, id
, mproperty
.offset
, value
)
217 # Replace the value of an attribute in an instance
218 # `instance` is the attributes array of the receiver
219 # `vtable` is the pointer to the virtual table of the class (of the receiver)
220 # `mask` is the perfect hashing mask of the class
221 # `id` is the identifier of the class
222 # `offset` is the relative offset of this attribute
223 # `value` is the new value for this attribute
224 private fun write_attribute_ph
(instance
: Pointer, vtable
: Pointer, mask
: Int, id
: Int, offset
: Int, value
: Instance) `{
225 // Perfect hashing position
227 long unsigned int *pointer = (long unsigned int*)(((long int *)vtable)[-hv]);
229 // pointer+1 is the position where the delta of the class is
230 int absolute_offset = *(pointer + 1);
232 ((Instance *)instance)[absolute_offset + offset] = value;
233 Instance_incr_ref(value);
238 # A reference to the virtual table of this class
239 var vtable
: nullable VTable
241 # True when the class is effectively loaded by the vm, false otherwise
242 var loaded
: Bool = false
244 # For each loaded subclass, keep the position of the group of attributes
245 # introduced by self class in the object
246 var positions_attributes
: HashMap[MClass, Int] = new HashMap[MClass, Int]
248 # For each loaded subclass, keep the position of the group of methods
249 # introduced by self class in the vtable
250 var positions_methods
: HashMap[MClass, Int] = new HashMap[MClass, Int]
252 # Allocates a VTable for this class and gives it an id
253 private fun make_vt
(v
: VirtualMachine)
255 if loaded
then return
257 # `superclasses` contains the order of superclasses for virtual tables
258 var superclasses
= superclasses_ordering
(v
)
259 superclasses
.remove
(self)
261 # Make_vt for super-classes
262 var ids
= new Array[Int]
263 var nb_methods
= new Array[Int]
264 var nb_attributes
= new Array[Int]
266 # Absolute offset of the beginning of the attributes table
267 var offset_attributes
= 0
268 # Absolute offset of the beginning of the methods table
269 var offset_methods
= 0
271 for parent
in superclasses
do
272 if not parent
.loaded
then parent
.make_vt
(v
)
274 # Get the number of introduced methods and attributes for this class
278 for p
in parent
.intro_mproperties
(none_visibility
) do
279 if p
isa MMethod then methods
+= 1
280 if p
isa MAttribute then
285 ids
.push
(parent
.vtable
.id
)
286 nb_methods
.push
(methods
)
287 nb_attributes
.push
(attributes
)
289 # Update `positions_attributes` and `positions_methods` in `parent`
290 update_positions
(offset_attributes
, offset_methods
, parent
)
292 offset_attributes
+= attributes
293 offset_methods
+= methods
296 # When all super-classes have their identifiers and vtables, allocate current one
297 allocate_vtable
(v
, ids
, nb_methods
, nb_attributes
, offset_attributes
, offset_methods
)
299 # The virtual table now needs to be filled with pointer to methods
302 # Allocate a single vtable
303 # `ids : Array of superclasses identifiers
304 # `nb_methods : Array which contain the number of introduced methods for each class in ids
305 # `nb_attributes : Array which contain the number of introduced attributes for each class in ids
306 # `offset_attributes : Offset from the beginning of the table of the group of attributes
307 # `offset_methods : Offset from the beginning of the table of the group of methods
308 private fun allocate_vtable
(v
: VirtualMachine, ids
: Array[Int], nb_methods
: Array[Int], nb_attributes
: Array[Int],
309 offset_attributes
: Int, offset_methods
: Int)
312 var idc
= new Array[Int]
314 vtable
.mask
= v
.ph
.pnand
(ids
, 1, idc
) - 1
316 vtable
.classname
= name
318 # Add current id to Array of super-ids
319 var ids_total
= new Array[Int]
320 ids_total
.add_all
(ids
)
321 ids_total
.push
(vtable
.id
)
323 var nb_methods_total
= new Array[Int]
324 var nb_attributes_total
= new Array[Int]
327 var nb_introduced_attributes
= 0
329 # For self attributes, fixing offsets
330 var relative_offset
= 0
331 for p
in intro_mproperties
(none_visibility
) do
332 if p
isa MMethod then self_methods
+= 1
333 if p
isa MAttribute then
334 nb_introduced_attributes
+= 1
335 p
.offset
= relative_offset
340 nb_methods_total
.add_all
(nb_methods
)
341 nb_methods_total
.push
(self_methods
)
343 nb_attributes_total
.add_all
(nb_attributes
)
344 nb_attributes_total
.push
(nb_introduced_attributes
)
346 # Save the offsets of self class
347 offset_attributes
+= nb_introduced_attributes
348 offset_methods
+= self_methods
349 update_positions
(offset_attributes
, offset_methods
, self)
351 # Since we have the number of attributes for each class, calculate the delta
352 var d
= calculate_delta
(nb_attributes_total
)
353 vtable
.internal_vtable
= v
.memory_manager
.init_vtable
(ids_total
, nb_methods_total
, d
, vtable
.mask
)
356 # Computes delta for each class
357 # A delta represents the offset for this group of attributes in the object
358 # `nb_attributes` : number of attributes for each class (classes are linearized from Object to current)
359 # return deltas for each class
360 private fun calculate_delta
(nb_attributes
: Array[Int]): Array[Int]
362 var deltas
= new Array[Int]
365 for nb
in nb_attributes
do
373 # Order superclasses of self
374 # Return the order of superclasses in runtime structures of this class
375 private fun superclasses_ordering
(v
: VirtualMachine): Array[MClass]
377 var superclasses
= new Array[MClass]
378 superclasses
.add_all
(ancestors
)
380 var res
= new Array[MClass]
381 if superclasses
.length
> 1 then
383 var ordering
= self.dfs
(v
, res
)
387 # There is no super-class, self is Object
392 # A kind of Depth-First-Search for superclasses ordering
393 # `v` : the current executed instance of VirtualMachine
394 # `res` : Result Array, ie current superclasses ordering
395 private fun dfs
(v
: VirtualMachine, res
: Array[MClass]): Array[MClass]
397 # Add this class at the beginning
400 var direct_parents
= self.in_hierarchy
(v
.mainmodule
).direct_greaters
.to_a
402 if direct_parents
.length
> 1 then
403 # Prefix represents the class which has the most properties
404 # we try to choose it in first to reduce the number of potential recompilations
407 for cl
in direct_parents
do
408 # If we never have visited this class
409 if not res
.has
(cl
) then
410 var properties_length
= cl
.all_mproperties
(v
.mainmodule
, none_visibility
).length
411 if properties_length
> max
then
412 max
= properties_length
418 if prefix
!= null then
419 # Add the prefix class ordering at the beginning of our sequence
420 var prefix_res
= new Array[MClass]
421 prefix_res
= prefix
.dfs
(v
, prefix_res
)
423 # Then we recurse on other classes
424 for cl
in direct_parents
do
426 res
= new Array[MClass]
430 if not prefix_res
.has
(cl_res
) then prefix_res
.push
(cl_res
)
439 if direct_parents
.length
> 0 then
440 res
= direct_parents
.first
.dfs
(v
, res
)
444 if not res
.has
(self) then res
.push
(self)
449 # Update positions of self class in `parent`
450 # `attributes_offset`: absolute offset of introduced attributes
451 # `methods_offset`: absolute offset of introduced methods
452 private fun update_positions
(attributes_offsets
: Int, methods_offset
:Int, parent
: MClass)
454 parent
.positions_attributes
[self] = attributes_offsets
455 parent
.positions_methods
[self] = methods_offset
459 redef class MAttribute
460 # Represents the relative offset of this attribute in the runtime instance
464 # Redef MutableInstance to improve implementation of attributes in objects
465 redef class MutableInstance
467 # C-array to store pointers to attributes of this Object
468 var internal_attributes
: Pointer
471 # Is the type of the initial value inside attributes
475 redef var model
: Model
476 protected init(model
: Model)
481 redef fun to_s
do return "InitType"
482 redef fun as_nullable
do return self
483 redef fun need_anchor
do return false
484 redef fun resolve_for
(mtype
, anchor
, mmodule
, cleanup_virtual
) do return self
485 redef fun can_resolve_for
(mtype
, anchor
, mmodule
) do return true
487 redef fun collect_mclassdefs
(mmodule
) do return new HashSet[MClassDef]
489 redef fun collect_mclasses
(mmodule
) do return new HashSet[MClass]
491 redef fun collect_mtypes
(mmodule
) do return new HashSet[MClassType]
494 # A VTable contains the virtual method table for the dispatch
495 # and informations to perform subtyping tests
497 # The mask to perform perfect hashing
498 var mask
: Int is noinit
500 # Unique identifier given by perfect hashing
501 var id
: Int is noinit
503 # Pointer to the c-allocated area, represents the virtual table
504 var internal_vtable
: Pointer is noinit
506 # The short classname of this class
507 var classname
: String is noinit
511 var vtable
: nullable VTable
514 # Handle memory, used for allocate virtual table and associated structures
517 # Allocate and fill a virtual table
518 fun init_vtable
(ids
: Array[Int], nb_methods
: Array[Int], nb_attributes
: Array[Int], mask
: Int): Pointer
520 # Allocate in C current virtual table
521 var res
= intern_init_vtable
(ids
, nb_methods
, nb_attributes
, mask
)
526 # Construct virtual tables with a bi-dimensional layout
527 private fun intern_init_vtable
(ids
: Array[Int], nb_methods
: Array[Int], deltas
: Array[Int], mask
: Int): Pointer
528 import Array[Int].length
, Array[Int].[] `{
530 // Allocate and fill current virtual table
532 int total_size = 0; // total size of this virtual table
533 int nb_classes = Array_of_Int_length(nb_methods);
534 for(i = 0; i<nb_classes; i++) {
535 /* - One for each method of this class
536 * - One for the delta (offset of this group of attributes in objects)
539 total_size += Array_of_Int__index(nb_methods, i);
543 // Add the size of the perfect hashtable (mask +1)
544 // Add one because we start to fill the vtable at position 1 (0 is the init position)
545 total_size += mask+2;
546 long unsigned int* vtable = malloc(sizeof(long unsigned int)*total_size);
548 // Initialisation to the first position of the virtual table (ie : Object)
549 long unsigned int *init = vtable + mask + 2;
550 for(i=0; i<total_size; i++)
551 vtable[i] = (long unsigned int)init;
553 // Set the virtual table to its position 0
554 // ie: after the hashtable
555 vtable = vtable + mask + 1;
557 int current_size = 1;
558 for(i = 0; i < nb_classes; i++) {
560 vtable[hv] contains a pointer to the group of introduced methods
561 For each superclasse we have in virtual table :
562 (id | delta | introduced methods)
564 int hv = mask & Array_of_Int__index(ids, i);
566 vtable[current_size] = Array_of_Int__index(ids, i);
567 vtable[current_size + 1] = Array_of_Int__index(deltas, i);
568 vtable[-hv] = (long unsigned int)&(vtable[current_size]);
571 current_size += Array_of_Int__index(nb_methods, i);