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Commit b51624b

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Implement invokevirtual instruction
When `invokevirtual` is called, Jvm pops the reference from the stack and related arguments, then executes method. Add a new test script: "Invokevirtual.java"
1 parent e1d5def commit b51624b

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4 files changed

+104
-18
lines changed

4 files changed

+104
-18
lines changed

‎Makefile‎

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -47,7 +47,8 @@ TESTS = \
4747
Caller \
4848
Constructor \
4949
Field \
50-
Static
50+
Static \
51+
Invokevirtual
5152

5253
check: $(addprefix tests/,$(TESTS:=-result.out))
5354

‎classfile.c‎

Lines changed: 0 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -279,13 +279,6 @@ method_t *get_methods(FILE *class_file, constant_pool_t *cp)
279279
assert(descriptor->tag == CONSTANT_Utf8 && "Expected a UTF8");
280280
method->descriptor = (char *) descriptor->info;
281281

282-
/* FIXME: this VM can only execute static methods, while every class
283-
* has a constructor method <init>
284-
*/
285-
if (strcmp(method->name, "<init>"))
286-
assert((info.access_flags & IS_STATIC) &&
287-
"Only static methods are supported by this VM.");
288-
289282
read_method_attributes(class_file, &info, &method->code, cp);
290283
}
291284

‎jvm.c‎

Lines changed: 75 additions & 10 deletions
Original file line numberDiff line numberDiff line change
@@ -172,14 +172,6 @@ static inline void ineg(stack_frame_t *op_stack)
172172
push_int(op_stack, -op1);
173173
}
174174

175-
static inline void invokevirtual(stack_frame_t *op_stack)
176-
{
177-
int64_t op = pop_int(op_stack);
178-
179-
/* FIXME: the implement is not correct. */
180-
printf("%" PRId64 "\n", op);
181-
}
182-
183175
static inline void iconst(stack_frame_t *op_stack, uint8_t current)
184176
{
185177
push_int(op_stack, current - i_iconst_0);
@@ -906,10 +898,83 @@ stack_entry_t *execute(method_t *method,
906898
}
907899

908900
/* Invoke instance method; dispatch based on class */
909-
case i_invokevirtual:
910-
invokevirtual(op_stack);
901+
case i_invokevirtual: {
902+
uint8_t param1 = code_buf[pc + 1], param2 = code_buf[pc + 2];
903+
uint16_t index = ((param1 << 8) | param2);
904+
905+
/* the method to be called */
906+
char *method_name, *method_descriptor, *class_name;
907+
class_name = find_method_info_from_index(index, clazz, &method_name,
908+
&method_descriptor);
909+
910+
/* to handle print method */
911+
if (!strcmp(class_name, "java/io/PrintStream")) {
912+
stack_entry_t element = top(op_stack);
913+
914+
switch (element.type) {
915+
/* integer */
916+
case STACK_ENTRY_INT:
917+
case STACK_ENTRY_SHORT:
918+
case STACK_ENTRY_BYTE:
919+
case STACK_ENTRY_LONG: {
920+
int64_t op = pop_int(op_stack);
921+
printf("%ld\n", op);
922+
break;
923+
}
924+
default:
925+
printf("print type (%d) is not supported\n", element.type);
926+
break;
927+
}
928+
pc += 3;
929+
break;
930+
}
931+
932+
/* FIXME: consider method modifier */
933+
class_file_t *target_class =
934+
find_or_add_class_to_heap(class_name, prefix);
935+
936+
method_t *method =
937+
find_method(method_name, method_descriptor, target_class);
938+
uint16_t num_params = get_number_of_parameters(method);
939+
local_variable_t own_locals[method->code.max_locals];
940+
memset(own_locals, 0, sizeof(own_locals));
941+
for (int i = num_params; i >= 1; i--) {
942+
pop_to_local(op_stack, &own_locals[i]);
943+
}
944+
object_t *obj = pop_ref(op_stack);
945+
946+
/* first argument is this pointer */
947+
own_locals[0].entry.ptr_value = obj;
948+
own_locals[0].type = STACK_ENTRY_REF;
949+
950+
stack_entry_t *exec_res = execute(method, own_locals, target_class);
951+
switch (exec_res->type) {
952+
case STACK_ENTRY_BYTE:
953+
push_int(op_stack, exec_res->entry.char_value);
954+
break;
955+
case STACK_ENTRY_SHORT:
956+
push_int(op_stack, exec_res->entry.short_value);
957+
break;
958+
case STACK_ENTRY_INT:
959+
push_int(op_stack, exec_res->entry.int_value);
960+
break;
961+
case STACK_ENTRY_LONG:
962+
push_long(op_stack, exec_res->entry.long_value);
963+
break;
964+
case STACK_ENTRY_REF:
965+
push_ref(op_stack, exec_res->entry.ptr_value);
966+
break;
967+
case STACK_ENTRY_NONE:
968+
/* nothing */
969+
break;
970+
default:
971+
assert(0 && "unknown return type");
972+
}
973+
974+
free(exec_res);
911975
pc += 3;
912976
break;
977+
}
913978

914979
/* Push int constant */
915980
case i_iconst_m1:

‎tests/Invokevirtual.java‎

Lines changed: 27 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,27 @@
1+
class InvokevirtualA {
2+
void print(int val) {
3+
System.out.println(val);
4+
}
5+
}
6+
7+
class InvokevirtualB {
8+
void print(InvokevirtualA obj, int val) {
9+
obj.print(val);
10+
}
11+
}
12+
13+
class Invokevirtual {
14+
int a;
15+
public void print() {
16+
System.out.println(a);
17+
}
18+
public static void main(String args[]) {
19+
Invokevirtual x = new Invokevirtual();
20+
InvokevirtualA obj1 = new InvokevirtualA();
21+
InvokevirtualB obj2 = new InvokevirtualB();
22+
x.a = 3;
23+
x.print();
24+
obj1.print(2);
25+
obj2.print(obj1, 3);
26+
}
27+
}

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