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Commit 15a4a3e

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Support parent fields in getfield and putfield
When pitifulvm create a new object, it will create the object itself and all its parents as objects and use linked list to link all related objects. When `getfield` or `putfield` are called, pitifulvm will try to find fields along the linked list. Update `Inherit.java` in order to test parent fields.
1 parent 7331be2 commit 15a4a3e

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7 files changed

+89
-25
lines changed

7 files changed

+89
-25
lines changed

‎.clang-format‎

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -13,3 +13,5 @@ UseTab: Never
1313
IndentWidth: 4
1414
BreakBeforeBraces: Linux
1515
AccessModifierOffset: -4
16+
ForEachMacros:
17+
- list_for_each

‎classfile.h‎

Lines changed: 3 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -54,13 +54,15 @@ typedef struct {
5454
variable_t *static_var; /* store static fields in the class */
5555
} field_t;
5656

57-
typedef struct {
57+
typedef struct class_file{
5858
constant_pool_t constant_pool;
5959
class_info_t *info;
6060
method_t *methods;
6161
field_t *fields;
6262
u2 fields_count;
6363
bool initialized;
64+
struct class_file *next;
65+
struct class_file *prev;
6466
} class_file_t;
6567

6668
typedef struct {

‎jvm.c‎

Lines changed: 22 additions & 14 deletions
Original file line numberDiff line numberDiff line change
@@ -12,6 +12,7 @@
1212
#include "class-heap.h"
1313
#include "classfile.h"
1414
#include "constant-pool.h"
15+
#include "list.h"
1516
#include "object-heap.h"
1617
#include "stack.h"
1718

@@ -1114,7 +1115,11 @@ stack_entry_t *execute(method_t *method,
11141115
find_field_info_from_index(index, clazz, &field_name,
11151116
&field_descriptor);
11161117

1117-
variable_t *addr = find_field_addr(obj, field_name);
1118+
variable_t *addr = NULL;
1119+
while (!addr) {
1120+
addr = find_field_addr(obj, field_name);
1121+
obj = obj->parent;
1122+
}
11181123

11191124
switch (field_descriptor[0]) {
11201125
case 'I':
@@ -1166,7 +1171,11 @@ stack_entry_t *execute(method_t *method,
11661171
find_field_info_from_index(index, clazz, &field_name,
11671172
&field_descriptor);
11681173

1169-
variable_t *var = find_field_addr(obj, field_name);
1174+
variable_t *var = NULL;
1175+
while (!var) {
1176+
var = find_field_addr(obj, field_name);
1177+
obj = obj->parent;
1178+
}
11701179

11711180
switch (field_descriptor[0]) {
11721181
case 'I':
@@ -1197,22 +1206,20 @@ stack_entry_t *execute(method_t *method,
11971206
char *class_name = find_class_name_from_index(index, clazz);
11981207
class_file_t *target_class;
11991208

1200-
/* FIXME: use linked list to prevent wasted space */
1201-
class_file_t**stack=malloc(sizeof(class_file_t*) *100);
1202-
size_tcount=0;
1203-
while (true) {
1209+
class_file_t*list =calloc(1, sizeof(class_file_t));
1210+
init_list(list);
1211+
1212+
while (strcmp(class_name, "java/lang/Object")) {
12041213
find_or_add_class_to_heap(class_name, prefix, &target_class);
12051214
assert(target_class && "Failed to load class in i_new");
1206-
stack[count++] =target_class;
1215+
list_add(target_class, list);
12071216
class_name = find_class_name_from_index(
12081217
target_class->info->super_class, target_class);
1209-
if (!strcmp(class_name, "java/lang/Object"))
1210-
break;
12111218
}
12121219

1213-
/* call static initialization */
1214-
while (count) {
1215-
target_class=stack[--count];
1220+
/* reversely call static initialization if class have not been
1221+
* initialized */
1222+
list_for_each (target_class, list) {
12161223
if (target_class->initialized)
12171224
continue;
12181225
target_class->initialized = true;
@@ -1226,10 +1233,11 @@ stack_entry_t *execute(method_t *method,
12261233
free(exec_res);
12271234
}
12281235
}
1229-
free(stack);
12301236

1231-
object_t *object = create_object(target_class);
1237+
object_t *object = create_object(list);
12321238
push_ref(op_stack, object);
1239+
list_del(list);
1240+
free(list);
12331241

12341242
pc += 3;
12351243
break;

‎list.h‎

Lines changed: 18 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,18 @@
1+
#pragma once
2+
3+
#define init_list(list) list->prev = list->next = list;
4+
5+
#define list_is_head(list, head) (list == head)
6+
7+
#define list_add(new, head) \
8+
head->next->prev = new; \
9+
new->next = head->next; \
10+
new->prev = head; \
11+
head->next = new;
12+
13+
#define list_del(entry) \
14+
entry->prev->next = entry->next; \
15+
entry->next->prev = entry->prev;
16+
17+
#define list_for_each(pos, head) \
18+
for (pos = (head)->next; !list_is_head(pos, (head)); pos = pos->next)

‎object-heap.c‎

Lines changed: 26 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -12,15 +12,29 @@ void init_object_heap()
1212
object_heap.length = 0;
1313
}
1414

15+
/**
16+
* Create an java object.
17+
*
18+
* @param clazz the list of classes that contains the created class and all its
19+
* parent classess
20+
* @return the object that wanted to be created
21+
*/
1522
object_t *create_object(class_file_t *clazz)
1623
{
17-
object_t *new_obj = malloc(sizeof(object_t));
18-
new_obj->fields_count = clazz->fields_count;
19-
new_obj->value = calloc(sizeof(variable_t), new_obj->fields_count);
20-
for (int i = 0; i < clazz->fields_count; ++i) {
21-
new_obj->value[i].type = VAR_NONE;
24+
object_t *new_obj = NULL, *parent = NULL;
25+
class_file_t *pos;
26+
list_for_each (pos, clazz) {
27+
new_obj = malloc(sizeof(object_t));
28+
new_obj->fields_count = pos->fields_count;
29+
new_obj->value = calloc(sizeof(variable_t), new_obj->fields_count);
30+
new_obj->parent = parent;
31+
for (int i = 0; i < pos->fields_count; ++i) {
32+
new_obj->value[i].type = VAR_NONE;
33+
}
34+
new_obj->class = pos;
35+
parent = new_obj;
2236
}
23-
new_obj->class=clazz;
37+
/* only store object that really is needed in object heap */
2438
object_heap.objects[object_heap.length++] = new_obj;
2539

2640
return new_obj;
@@ -34,15 +48,18 @@ variable_t *find_field_addr(object_t *obj, char *name)
3448
return &obj->value[i];
3549
}
3650
}
37-
assert(0 && "Can't find field in the object");
3851
return NULL;
3952
}
4053

4154
void free_object_heap()
4255
{
4356
for (int i = 0; i < object_heap.length; ++i) {
44-
free(object_heap.objects[i]->value);
45-
free(object_heap.objects[i]);
57+
/* free object and all its parent */
58+
for (object_t *cur = object_heap.objects[i], *next; cur; cur = next) {
59+
next = cur->parent;
60+
free(cur->value);
61+
free(cur);
62+
}
4663
}
4764
free(object_heap.objects);
4865
}

‎object-heap.h‎

Lines changed: 3 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1,11 +1,13 @@
11
#pragma once
22

33
#include "classfile.h"
4+
#include "list.h"
45

5-
typedef struct {
6+
typedef struct object{
67
variable_t *value;
78
class_file_t *class;
89
size_t fields_count;
10+
struct object *parent;
911
} object_t;
1012

1113
typedef struct {

‎tests/Inherit.java‎

Lines changed: 15 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,6 @@
11
public class Inherit {
22
static int x = 1;
3+
int y = 5;
34

45
public static void static_call() {
56
System.out.println(1);
@@ -27,6 +28,20 @@ public static void main(String[] args) {
2728
System.out.println(objA.x);
2829
System.out.println(objB.x);
2930

31+
/* check fields */
32+
System.out.println(obj.y);
33+
System.out.println(objA.y);
34+
System.out.println(objB.y);
35+
obj.y = 2;
36+
System.out.println(obj.y);
37+
System.out.println(objA.y);
38+
System.out.println(objB.y);
39+
objA.y = 3;
40+
objB.y = 5;
41+
System.out.println(obj.y);
42+
System.out.println(objA.y);
43+
System.out.println(objB.y);
44+
3045
/* check static methods inheritance (compiler will replace objects with classes) */
3146
obj.static_call();
3247
objA.static_call();

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