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Commit 7331be2

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authored
Merge pull request #12 from hankluo6/inheritance
Handle class inheritance correctly
2 parents ad67942 + 71875f4 commit 7331be2

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7 files changed

+218
-49
lines changed

7 files changed

+218
-49
lines changed

‎Makefile‎

Lines changed: 3 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -48,7 +48,9 @@ TESTS = \
4848
Constructor \
4949
Field \
5050
Static \
51-
Invokevirtual
51+
Invokevirtual \
52+
Inherit \
53+
Initializer
5254

5355
check: $(addprefix tests/,$(TESTS:=-result.out))
5456

‎class-heap.c‎

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -95,6 +95,7 @@ void free_class_heap()
9595
free(constant->info);
9696
}
9797
free(class_heap.class_info[i]->clazz->constant_pool.constant_pool);
98+
free(class_heap.class_info[i]->clazz->info);
9899

99100
field_t *field = class_heap.class_info[i]->clazz->fields;
100101
for (u2 j = 0; j < class_heap.class_info[i]->clazz->fields_count;

‎classfile.c‎

Lines changed: 10 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -9,13 +9,13 @@ class_header_t get_class_header(FILE *class_file)
99
};
1010
}
1111

12-
class_info_t get_class_info(FILE *class_file)
12+
class_info_t *get_class_info(FILE *class_file)
1313
{
14-
class_info_t info = {
15-
.access_flags = read_u2(class_file),
16-
.this_class = read_u2(class_file),
17-
.super_class = read_u2(class_file),
18-
};
14+
class_info_t *info = malloc(sizeof(class_info_t));
15+
info->access_flags = read_u2(class_file);
16+
info->this_class = read_u2(class_file);
17+
info->super_class = read_u2(class_file);
18+
1919
u2 interfaces_count = read_u2(class_file);
2020
assert(!interfaces_count && "This VM does not support interfaces.");
2121
return info;
@@ -303,12 +303,15 @@ class_file_t get_class(FILE *class_file)
303303
class_file_t clazz = {.constant_pool = get_constant_pool(class_file)};
304304

305305
/* Read information about the class that was compiled. */
306-
get_class_info(class_file);
306+
clazz.info=get_class_info(class_file);
307307

308308
/* Read the list of fields */
309309
clazz.fields = get_fields(class_file, &clazz.constant_pool, &clazz);
310310

311311
/* Read the list of static methods */
312312
clazz.methods = get_methods(class_file, &clazz.constant_pool);
313+
314+
clazz.initialized = false;
315+
313316
return clazz;
314317
}

‎classfile.h‎

Lines changed: 3 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -56,9 +56,11 @@ typedef struct {
5656

5757
typedef struct {
5858
constant_pool_t constant_pool;
59+
class_info_t *info;
5960
method_t *methods;
6061
field_t *fields;
6162
u2 fields_count;
63+
bool initialized;
6264
} class_file_t;
6365

6466
typedef struct {
@@ -67,7 +69,7 @@ typedef struct {
6769
} meta_class_t;
6870

6971
class_header_t get_class_header(FILE *class_file);
70-
class_info_t get_class_info(FILE *class_file);
72+
class_info_t *get_class_info(FILE *class_file);
7173
method_t *get_methods(FILE *class_file, constant_pool_t *cp);
7274
void read_method_attributes(FILE *class_file,
7375
method_info *info,

‎jvm.c‎

Lines changed: 110 additions & 40 deletions
Original file line numberDiff line numberDiff line change
@@ -263,12 +263,28 @@ stack_entry_t *execute(method_t *method,
263263

264264
/* the method to be called */
265265
char *method_name, *method_descriptor, *class_name;
266-
class_name = find_method_info_from_index(index, clazz, &method_name,
267-
&method_descriptor);
266+
method_t *own_method = NULL;
267+
class_file_t *target_class = NULL;
268+
269+
/* recursively find method from child to parent */
270+
while (!own_method) {
271+
if (!target_class)
272+
class_name = find_method_info_from_index(
273+
index, clazz, &method_name, &method_descriptor);
274+
else
275+
class_name = find_class_name_from_index(
276+
target_class->info->super_class, target_class);
277+
find_or_add_class_to_heap(class_name, prefix, &target_class);
278+
assert(target_class &&
279+
"Failed to load class in i_invokestatic");
280+
own_method =
281+
find_method(method_name, method_descriptor, target_class);
282+
}
268283

269-
class_file_t *target_class;
270-
if (find_or_add_class_to_heap(class_name, prefix, &target_class)) {
271-
/* Call static initialization */
284+
/* call static initialization. Only the class that contains this
285+
* method should do static initialization */
286+
if (!target_class->initialized) {
287+
target_class->initialized = true;
272288
method_t *method = find_method("<clinit>", "()V", target_class);
273289
if (method) {
274290
local_variable_t own_locals[method->code.max_locals];
@@ -279,10 +295,7 @@ stack_entry_t *execute(method_t *method,
279295
free(exec_res);
280296
}
281297
}
282-
assert(target_class && "Failed to load class in invokestatic");
283298

284-
method_t *own_method =
285-
find_method(method_name, method_descriptor, target_class);
286299
uint16_t num_params = get_number_of_parameters(own_method);
287300
local_variable_t own_locals[own_method->code.max_locals];
288301
for (int i = num_params - 1; i >= 0; i--)
@@ -794,19 +807,33 @@ stack_entry_t *execute(method_t *method,
794807
uint16_t index = ((param1 << 8) | param2);
795808

796809
char *field_name, *field_descriptor, *class_name;
810+
field_t *field = NULL;
811+
class_file_t *target_class = NULL;
812+
797813
class_name = find_field_info_from_index(index, clazz, &field_name,
798814
&field_descriptor);
799-
800815
/* skip java.lang.System in order to support java print
801816
* method */
802817
if (!strcmp(class_name, "java/lang/System")) {
803818
pc += 3;
804819
break;
805820
}
806821

807-
class_file_t *target_class;
808-
if (find_or_add_class_to_heap(class_name, prefix, &target_class)) {
809-
/* Call static initialization */
822+
while (!field) {
823+
if (target_class)
824+
class_name = find_class_name_from_index(
825+
target_class->info->super_class, target_class);
826+
827+
find_or_add_class_to_heap(class_name, prefix, &target_class);
828+
assert(target_class && "Failed to load class in i_getstatic");
829+
830+
field = find_field(field_name, field_descriptor, target_class);
831+
}
832+
833+
/* call static initialization. Only the class that contains this
834+
* field should do static initialization */
835+
if (!target_class->initialized) {
836+
target_class->initialized = true;
810837
method_t *method = find_method("<clinit>", "()V", target_class);
811838
if (method) {
812839
local_variable_t own_locals[method->code.max_locals];
@@ -818,9 +845,6 @@ stack_entry_t *execute(method_t *method,
818845
}
819846
}
820847

821-
field_t *field =
822-
find_field(field_name, field_descriptor, target_class);
823-
824848
switch (field_descriptor[0]) {
825849
case 'B':
826850
/* signed byte */
@@ -866,12 +890,33 @@ stack_entry_t *execute(method_t *method,
866890
uint16_t index = ((param1 << 8) | param2);
867891

868892
char *field_name, *field_descriptor, *class_name;
893+
field_t *field = NULL;
894+
class_file_t *target_class = NULL;
869895
class_name = find_field_info_from_index(index, clazz, &field_name,
870896
&field_descriptor);
871897

872-
class_file_t *target_class;
873-
if (find_or_add_class_to_heap(class_name, prefix, &target_class)) {
874-
/* Call static initialization */
898+
/* skip java.lang.System in order to support java print
899+
* method */
900+
if (!strcmp(class_name, "java/lang/System")) {
901+
pc += 3;
902+
break;
903+
}
904+
905+
while (!field) {
906+
if (target_class)
907+
class_name = find_class_name_from_index(
908+
target_class->info->super_class, target_class);
909+
910+
find_or_add_class_to_heap(class_name, prefix, &target_class);
911+
assert(target_class && "Failed to load class in i_putstatic");
912+
913+
field = find_field(field_name, field_descriptor, target_class);
914+
}
915+
916+
/* call static initialization. Only the class that contains this
917+
* field should do static initialization */
918+
if (!target_class->initialized) {
919+
target_class->initialized = true;
875920
method_t *method = find_method("<clinit>", "()V", target_class);
876921
if (method) {
877922
local_variable_t own_locals[method->code.max_locals];
@@ -882,8 +927,6 @@ stack_entry_t *execute(method_t *method,
882927
free(exec_res);
883928
}
884929
}
885-
field_t *field =
886-
find_field(field_name, field_descriptor, target_class);
887930

888931
switch (field_descriptor[0]) {
889932
case 'B':
@@ -938,6 +981,9 @@ stack_entry_t *execute(method_t *method,
938981

939982
/* the method to be called */
940983
char *method_name, *method_descriptor, *class_name;
984+
class_file_t *target_class = NULL;
985+
method_t *method = NULL;
986+
941987
class_name = find_method_info_from_index(index, clazz, &method_name,
942988
&method_descriptor);
943989

@@ -964,9 +1010,22 @@ stack_entry_t *execute(method_t *method,
9641010
}
9651011

9661012
/* FIXME: consider method modifier */
967-
class_file_t *target_class;
968-
if (find_or_add_class_to_heap(class_name, prefix, &target_class)) {
969-
/* Call static initialization */
1013+
/* recursively find method from child to parent */
1014+
while (!method) {
1015+
if (target_class)
1016+
class_name = find_class_name_from_index(
1017+
target_class->info->super_class, target_class);
1018+
find_or_add_class_to_heap(class_name, prefix, &target_class);
1019+
assert(target_class &&
1020+
"Failed to load class in i_invokevirtual");
1021+
method =
1022+
find_method(method_name, method_descriptor, target_class);
1023+
}
1024+
1025+
/* call static initialization. Only the class that contains this
1026+
* method should do static initialization */
1027+
if (!target_class->initialized) {
1028+
target_class->initialized = true;
9701029
method_t *method = find_method("<clinit>", "()V", target_class);
9711030
if (method) {
9721031
local_variable_t own_locals[method->code.max_locals];
@@ -977,8 +1036,7 @@ stack_entry_t *execute(method_t *method,
9771036
free(exec_res);
9781037
}
9791038
}
980-
method_t *method =
981-
find_method(method_name, method_descriptor, target_class);
1039+
9821040
uint16_t num_params = get_number_of_parameters(method);
9831041
local_variable_t own_locals[method->code.max_locals];
9841042
memset(own_locals, 0, sizeof(own_locals));
@@ -1138,8 +1196,26 @@ stack_entry_t *execute(method_t *method,
11381196

11391197
char *class_name = find_class_name_from_index(index, clazz);
11401198
class_file_t *target_class;
1141-
if (find_or_add_class_to_heap(class_name, prefix, &target_class)) {
1142-
/* Call static initialization */
1199+
1200+
/* FIXME: use linked list to prevent wasted space */
1201+
class_file_t **stack = malloc(sizeof(class_file_t *) * 100);
1202+
size_t count = 0;
1203+
while (true) {
1204+
find_or_add_class_to_heap(class_name, prefix, &target_class);
1205+
assert(target_class && "Failed to load class in i_new");
1206+
stack[count++] = target_class;
1207+
class_name = find_class_name_from_index(
1208+
target_class->info->super_class, target_class);
1209+
if (!strcmp(class_name, "java/lang/Object"))
1210+
break;
1211+
}
1212+
1213+
/* call static initialization */
1214+
while (count) {
1215+
target_class = stack[--count];
1216+
if (target_class->initialized)
1217+
continue;
1218+
target_class->initialized = true;
11431219
method_t *method = find_method("<clinit>", "()V", target_class);
11441220
if (method) {
11451221
local_variable_t own_locals[method->code.max_locals];
@@ -1150,7 +1226,7 @@ stack_entry_t *execute(method_t *method,
11501226
free(exec_res);
11511227
}
11521228
}
1153-
assert(target_class&&"Failed to load class in new");
1229+
free(stack);
11541230

11551231
object_t *object = create_object(target_class);
11561232
push_ref(op_stack, object);
@@ -1178,8 +1254,12 @@ stack_entry_t *execute(method_t *method,
11781254
}
11791255

11801256
class_file_t *target_class;
1181-
if (find_or_add_class_to_heap(class_name, prefix, &target_class)) {
1182-
/* Call static initialization */
1257+
find_or_add_class_to_heap(class_name, prefix, &target_class);
1258+
assert(target_class && "Failed to load class in i_invokespecial");
1259+
1260+
/* call static initialization */
1261+
if (!target_class->initialized) {
1262+
target_class->initialized = true;
11831263
method_t *method = find_method("<clinit>", "()V", target_class);
11841264
if (method) {
11851265
local_variable_t own_locals[method->code.max_locals];
@@ -1190,7 +1270,6 @@ stack_entry_t *execute(method_t *method,
11901270
free(exec_res);
11911271
}
11921272
}
1193-
assert(target_class && "Failed to load class in i_invokespecial");
11941273

11951274
/* find constructor method from class */
11961275
method_t *constructor =
@@ -1254,15 +1333,6 @@ int main(int argc, char *argv[])
12541333
prefix[match - argv[1] + 1] = '0円';
12551334
}
12561335

1257-
method_t *method = find_method("<clinit>", "()V", clazz);
1258-
if (method) {
1259-
local_variable_t own_locals[method->code.max_locals];
1260-
stack_entry_t *exec_res = execute(method, own_locals, clazz);
1261-
assert(exec_res->type == STACK_ENTRY_NONE &&
1262-
"<clinit> must not return a value");
1263-
free(exec_res);
1264-
}
1265-
12661336
/* execute the main method if found */
12671337
method_t *main_method =
12681338
find_method("main", "([Ljava/lang/String;)V", clazz);

‎tests/Inherit.java‎

Lines changed: 54 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,54 @@
1+
public class Inherit {
2+
static int x = 1;
3+
4+
public static void static_call() {
5+
System.out.println(1);
6+
}
7+
8+
public void virtual_call() {
9+
System.out.println(2);
10+
}
11+
12+
public static void main(String[] args) {
13+
Inherit obj = new Inherit();
14+
InheritA objA = new InheritA();
15+
InheritB objB = new InheritB();
16+
17+
/* check shared static fields */
18+
System.out.println(obj.x);
19+
System.out.println(objA.x);
20+
System.out.println(objB.x);
21+
obj.x = 2;
22+
System.out.println(obj.x);
23+
System.out.println(objA.x);
24+
System.out.println(objB.x);
25+
objA.x = 3;
26+
System.out.println(obj.x);
27+
System.out.println(objA.x);
28+
System.out.println(objB.x);
29+
30+
/* check static methods inheritance (compiler will replace objects with classes) */
31+
obj.static_call();
32+
objA.static_call();
33+
objB.static_call();
34+
35+
/* check virtual methods inheritance */
36+
obj.virtual_call();
37+
objA.virtual_call();
38+
objB.virtual_call();
39+
}
40+
}
41+
42+
class InheritA extends Inherit {
43+
44+
}
45+
46+
class InheritB extends InheritA {
47+
/* check override */
48+
public void virtual_call() {
49+
System.out.println(3);
50+
}
51+
public static void static_call() {
52+
System.out.println(4);
53+
}
54+
}

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