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Commit 6c5646a

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authored
Merge pull request #8 from hankluo6/field
Add more class related opcodes
2 parents 266e518 + 7d71178 commit 6c5646a

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11 files changed

+292
-5
lines changed

11 files changed

+292
-5
lines changed

‎Makefile‎

Lines changed: 3 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -45,7 +45,9 @@ TESTS = \
4545
Recursion \
4646
Long \
4747
Caller \
48-
Constructor
48+
Constructor \
49+
Field \
50+
Static
4951

5052
check: $(addprefix tests/,$(TESTS:=-result.out))
5153

‎class-heap.c‎

Lines changed: 5 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -91,6 +91,11 @@ void free_class_heap()
9191
free(constant->info);
9292
}
9393
free(class_heap.class_info[i]->clazz->constant_pool.constant_pool);
94+
95+
field_t *field = class_heap.class_info[i]->clazz->fields;
96+
for (u2 j = 0; j < class_heap.class_info[i]->clazz->fields_count;
97+
j++, field++)
98+
free(field->static_var);
9499
free(class_heap.class_info[i]->clazz->fields);
95100

96101
for (method_t *method = class_heap.class_info[i]->clazz->methods;

‎classfile.c‎

Lines changed: 22 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -31,6 +31,27 @@ uint16_t get_number_of_parameters(method_t *method)
3131
return strlen(method->descriptor) - 3;
3232
}
3333

34+
/**
35+
* Find the field with the given name and signature.
36+
* The difference between `find_field` and `object_heap:find_field_addr`
37+
* is that `find_field` is used to find class level field (i.e. static field),
38+
* and `find_field_addr` is used to find object level field.
39+
*
40+
* @param name the field name
41+
* @param desc the field descriptor string, e.g. "(I)I"
42+
* @param clazz the parsed class file
43+
* @return the field if it was found, or NULL
44+
*/
45+
field_t *find_field(const char *name, const char *desc, class_file_t *clazz)
46+
{
47+
field_t *field = clazz->fields;
48+
for (u2 i = 0; i < clazz->fields_count; ++i, field++) {
49+
if (!(strcmp(name, field->name) || strcmp(desc, field->descriptor)))
50+
return field;
51+
}
52+
return NULL;
53+
}
54+
3455
/**
3556
* Find the method with the given name and signature.
3657
* The descriptor is necessary because Java allows method overloading.
@@ -218,6 +239,7 @@ field_t *get_fields(FILE *class_file, constant_pool_t *cp, class_file_t *clazz)
218239
const_pool_info *descriptor = get_constant(cp, info.descriptor_index);
219240
assert(descriptor->tag == CONSTANT_Utf8 && "Expected a UTF8");
220241
field->descriptor = (char *) descriptor->info;
242+
field->static_var = malloc(sizeof(variable_t));
221243

222244
read_field_attributes(class_file, &info);
223245
}

‎classfile.h‎

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -51,6 +51,7 @@ typedef struct {
5151
char *class_name;
5252
char *name;
5353
char *descriptor;
54+
variable_t *static_var; /* store static fields in the class */
5455
} field_t;
5556

5657
typedef struct {
@@ -73,6 +74,7 @@ void read_method_attributes(FILE *class_file,
7374
code_t *code,
7475
constant_pool_t *cp);
7576
uint16_t get_number_of_parameters(method_t *method);
77+
field_t *find_field(const char *name, const char *desc, class_file_t *clazz);
7678
method_t *find_method(const char *name, const char *desc, class_file_t *clazz);
7779
method_t *find_method_from_index(uint16_t idx, class_file_t *clazz);
7880
class_file_t get_class(FILE *class_file);

‎jvm.c‎

Lines changed: 204 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -94,6 +94,9 @@ typedef enum {
9494
i_areturn = 0xb0,
9595
i_return = 0xb1,
9696
i_getstatic = 0xb2,
97+
i_putstatic = 0xb3,
98+
i_getfield = 0xb4,
99+
i_putfield = 0xb5,
97100
i_invokevirtual = 0xb6,
98101
i_invokespecial = 0xb7,
99102
i_invokestatic = 0xb8,
@@ -783,10 +786,124 @@ stack_entry_t *execute(method_t *method,
783786
break;
784787

785788
/* Get static field from class */
786-
case i_getstatic:
787-
/* FIXME: unimplemented */
789+
case i_getstatic: {
790+
uint8_t param1 = code_buf[pc + 1], param2 = code_buf[pc + 2];
791+
uint16_t index = ((param1 << 8) | param2);
792+
793+
char *field_name, *field_descriptor, *class_name;
794+
class_name = find_field_info_from_index(index, clazz, &field_name,
795+
&field_descriptor);
796+
797+
/* skip java.lang.System in order to support java print
798+
* method */
799+
if (!strcmp(class_name, "java/lang/System")) {
800+
pc += 3;
801+
break;
802+
}
803+
804+
class_file_t *target_class =
805+
find_or_add_class_to_heap(class_name, prefix);
806+
field_t *field =
807+
find_field(field_name, field_descriptor, target_class);
808+
809+
switch (field_descriptor[0]) {
810+
case 'B':
811+
/* signed byte */
812+
push_byte(op_stack, field->static_var->value.char_value);
813+
break;
814+
case 'C':
815+
/* FIXME: complete Unicode handling */
816+
/* unicode character code */
817+
push_short(op_stack, field->static_var->value.short_value);
818+
break;
819+
case 'I':
820+
/* integer */
821+
push_int(op_stack, field->static_var->value.int_value);
822+
break;
823+
case 'J':
824+
/* long integer */
825+
push_long(op_stack, field->static_var->value.long_value);
826+
break;
827+
case 'S':
828+
/* signed short */
829+
push_short(op_stack, field->static_var->value.short_value);
830+
break;
831+
case 'Z':
832+
/* true or false */
833+
push_byte(op_stack, field->static_var->value.char_value);
834+
break;
835+
case 'L':
836+
/* an instance of class */
837+
push_ref(op_stack, field->static_var->value.ptr_value);
838+
break;
839+
default:
840+
fprintf(stderr, "Unknown field descriptor %c\n",
841+
field_descriptor[0]);
842+
exit(1);
843+
}
788844
pc += 3;
789845
break;
846+
}
847+
848+
/* Put static field to class */
849+
case i_putstatic: {
850+
uint8_t param1 = code_buf[pc + 1], param2 = code_buf[pc + 2];
851+
uint16_t index = ((param1 << 8) | param2);
852+
853+
char *field_name, *field_descriptor, *class_name;
854+
class_name = find_field_info_from_index(index, clazz, &field_name,
855+
&field_descriptor);
856+
857+
class_file_t *target_class =
858+
find_or_add_class_to_heap(class_name, prefix);
859+
field_t *field =
860+
find_field(field_name, field_descriptor, target_class);
861+
862+
switch (field_descriptor[0]) {
863+
case 'B':
864+
/* signed byte */
865+
field->static_var->value.char_value = (u1) pop_int(op_stack);
866+
field->static_var->type = VAR_BYTE;
867+
break;
868+
case 'C':
869+
/* FIXME: complete Unicode handling */
870+
/* unicode character code */
871+
field->static_var->value.char_value = (u2) pop_int(op_stack);
872+
field->static_var->type = VAR_SHORT;
873+
break;
874+
case 'I':
875+
/* integer */
876+
field->static_var->value.int_value = (u4) pop_int(op_stack);
877+
field->static_var->type = VAR_INT;
878+
break;
879+
case 'J':
880+
/* long integer */
881+
field->static_var->value.long_value = (u8) pop_int(op_stack);
882+
field->static_var->type = VAR_LONG;
883+
break;
884+
case 'S':
885+
/* signed short */
886+
field->static_var->value.short_value = (u2) pop_int(op_stack);
887+
field->static_var->type = VAR_SHORT;
888+
break;
889+
case 'Z':
890+
/* true or false */
891+
field->static_var->value.char_value = (u1) pop_int(op_stack);
892+
field->static_var->type = VAR_BYTE;
893+
break;
894+
case 'L':
895+
/* an instance of class ClassName */
896+
field->static_var->value.ptr_value = pop_ref(op_stack);
897+
field->static_var->type = VAR_PTR;
898+
break;
899+
default:
900+
fprintf(stderr, "Unknown field descriptor %c\n",
901+
field_descriptor[0]);
902+
exit(1);
903+
}
904+
pc += 3;
905+
break;
906+
}
790907

791908
/* Invoke instance method; dispatch based on class */
792909
case i_invokevirtual:
@@ -820,6 +937,91 @@ stack_entry_t *execute(method_t *method,
820937
pc += 3;
821938
break;
822939

940+
/* Fetch field from object */
941+
case i_getfield: {
942+
uint8_t param1 = code_buf[pc + 1], param2 = code_buf[pc + 2];
943+
uint16_t index = ((param1 << 8) | param2);
944+
945+
object_t *obj = pop_ref(op_stack);
946+
char *field_name, *field_descriptor;
947+
find_field_info_from_index(index, clazz, &field_name,
948+
&field_descriptor);
949+
950+
variable_t *addr = find_field_addr(obj, field_name);
951+
952+
switch (field_descriptor[0]) {
953+
case 'I':
954+
push_int(op_stack, addr->value.int_value);
955+
break;
956+
case 'J':
957+
push_long(op_stack, addr->value.long_value);
958+
break;
959+
case 'L':
960+
push_ref(op_stack, addr->value.ptr_value);
961+
break;
962+
default:
963+
assert(0 && "Only support integer and reference field");
964+
break;
965+
}
966+
pc += 3;
967+
break;
968+
}
969+
970+
/* Set field in object */
971+
case i_putfield: {
972+
uint8_t param1 = code_buf[pc + 1], param2 = code_buf[pc + 2];
973+
uint16_t index = ((param1 << 8) | param2);
974+
int64_t value = 0;
975+
void *addr = NULL;
976+
977+
/* get prepared value from the stack */
978+
stack_entry_t element = top(op_stack);
979+
switch (element.type) {
980+
/* integer */
981+
case STACK_ENTRY_INT:
982+
case STACK_ENTRY_SHORT:
983+
case STACK_ENTRY_BYTE:
984+
case STACK_ENTRY_LONG:
985+
value = pop_int(op_stack);
986+
break;
987+
case STACK_ENTRY_REF:
988+
addr = pop_ref(op_stack);
989+
break;
990+
default:
991+
assert(0 && "Only support integer and reference field");
992+
break;
993+
}
994+
995+
object_t *obj = pop_ref(op_stack);
996+
997+
/* update value into object's field */
998+
char *field_name, *field_descriptor;
999+
find_field_info_from_index(index, clazz, &field_name,
1000+
&field_descriptor);
1001+
1002+
variable_t *var = find_field_addr(obj, field_name);
1003+
1004+
switch (field_descriptor[0]) {
1005+
case 'I':
1006+
var->value.int_value = (int32_t) value;
1007+
var->type = VAR_INT;
1008+
break;
1009+
case 'J':
1010+
var->value.long_value = value;
1011+
var->type = VAR_LONG;
1012+
break;
1013+
case 'L':
1014+
var->value.ptr_value = addr;
1015+
var->type = VAR_PTR;
1016+
break;
1017+
default:
1018+
assert(0 && "Only support integer and reference field");
1019+
break;
1020+
}
1021+
pc += 3;
1022+
break;
1023+
}
1024+
8231025
/* create new object */
8241026
case i_new: {
8251027
uint8_t param1 = code_buf[pc + 1], param2 = code_buf[pc + 2];

‎object-heap.c‎

Lines changed: 12 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -26,6 +26,18 @@ object_t *create_object(class_file_t *clazz)
2626
return new_obj;
2727
}
2828

29+
variable_t *find_field_addr(object_t *obj, char *name)
30+
{
31+
field_t *field = obj->class->fields;
32+
for (u2 i = 0; i < obj->class->fields_count; i++, field++) {
33+
if (!strcmp(field->name, name)) {
34+
return &obj->value[i];
35+
}
36+
}
37+
assert(0 && "Can't find field in the object");
38+
return NULL;
39+
}
40+
2941
void free_object_heap()
3042
{
3143
for (int i = 0; i < object_heap.length; ++i) {

‎object-heap.h‎

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -15,4 +15,5 @@ typedef struct {
1515

1616
void init_object_heap();
1717
void free_object_heap();
18-
object_t *create_object(class_file_t *clazz);
18+
object_t *create_object(class_file_t *clazz);
19+
variable_t *find_field_addr(object_t *obj, char *name);

‎stack.c‎

Lines changed: 5 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -43,6 +43,11 @@ void push_ref(stack_frame_t *stack, void *addr)
4343
stack->size++;
4444
}
4545

46+
stack_entry_t top(stack_frame_t *stack)
47+
{
48+
return stack->store[stack->size - 1];
49+
}
50+
4651
/* pop top of stack value and convert to 64 bits integer */
4752
int64_t stack_to_int(value_t *entry, size_t size)
4853
{

‎stack.h‎

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -43,4 +43,5 @@ int64_t pop_int(stack_frame_t *stack);
4343
void *pop_ref(stack_frame_t *stack);
4444
void pop_to_local(stack_frame_t *stack, local_variable_t *locals);
4545
size_t get_type_size(stack_entry_type_t type);
46-
int64_t stack_to_int(value_t *entry, size_t size);
46+
int64_t stack_to_int(value_t *entry, size_t size);
47+
stack_entry_t top(stack_frame_t *stack);

‎tests/Field.java‎

Lines changed: 12 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,12 @@
1+
class Field {
2+
Field(int a, int b, int c) {
3+
x = a;
4+
y = b;
5+
z = c;
6+
}
7+
public static void main(String[] args) {
8+
Field f = new Field(1, 2, 3);
9+
System.out.println(f.x + f.y + f.z);
10+
}
11+
int x, y, z;
12+
}

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