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jvm.c
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/* PitifulVM is a minimalist Java Virtual Machine implementation written in C.
*/
#include <assert.h>
#include <inttypes.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "class-heap.h"
#include "classfile.h"
#include "constant-pool.h"
#include "list.h"
#include "object-heap.h"
#include "stack.h"
typedef enum {
i_iconst_m1 = 0x2,
i_iconst_0 = 0x3,
i_iconst_1 = 0x4,
i_iconst_2 = 0x5,
i_iconst_3 = 0x6,
i_iconst_4 = 0x7,
i_iconst_5 = 0x8,
i_lconst_0 = 0x9,
i_lconst_1 = 0xa,
i_bipush = 0x10,
i_sipush = 0x11,
i_ldc = 0x12,
i_ldc2_w = 0x14,
i_iload = 0x15,
i_lload = 0x16,
i_aload = 0x19,
i_iload_0 = 0x1a,
i_iload_1 = 0x1b,
i_iload_2 = 0x1c,
i_iload_3 = 0x1d,
i_lload_0 = 0x1e,
i_lload_1 = 0x1f,
i_lload_2 = 0x20,
i_lload_3 = 0x21,
i_aload_0 = 0x2a,
i_aload_1 = 0x2b,
i_aload_2 = 0x2c,
i_aload_3 = 0x2d,
i_iaload = 0x2e,
i_laload = 0x2f,
i_aaload = 0x32,
i_baload = 0x33,
i_caload = 0x34,
i_saload = 0x35,
i_istore = 0x36,
i_lstore = 0x37,
i_astore = 0x3a,
i_istore_0 = 0x3b,
i_istore_1 = 0x3c,
i_istore_2 = 0x3d,
i_istore_3 = 0x3e,
i_lstore_0 = 0x3f,
i_lstore_1 = 0x40,
i_lstore_2 = 0x41,
i_lstore_3 = 0x42,
i_astore_0 = 0x4b,
i_astore_1 = 0x4c,
i_astore_2 = 0x4d,
i_astore_3 = 0x4e,
i_iastore = 0x4f,
i_lastore = 0x50,
i_aastore = 0x53,
i_bastore = 0x54,
i_castore = 0x55,
i_sastore = 0x56,
i_pop = 0x57,
i_dup = 0x59,
i_iadd = 0x60,
i_ladd = 0x61,
i_isub = 0x64,
i_lsub = 0x65,
i_imul = 0x68,
i_lmul = 0x69,
i_idiv = 0x6c,
i_ldiv = 0x6d,
i_irem = 0x70,
i_lrem = 0x71,
i_ineg = 0x74,
i_iinc = 0x84,
i_i2l = 0x85,
i_l2i = 0x88,
i_lcmp = 0x94,
i_ifeq = 0x99,
i_ifne = 0x9a,
i_iflt = 0x9b,
i_ifge = 0x9c,
i_ifgt = 0x9d,
i_ifle = 0x9e,
i_if_icmpeq = 0x9f,
i_if_icmpne = 0xa0,
i_if_icmplt = 0xa1,
i_if_icmpge = 0xa2,
i_if_icmpgt = 0xa3,
i_if_icmple = 0xa4,
i_goto = 0xa7,
i_ireturn = 0xac,
i_lreturn = 0xad,
i_areturn = 0xb0,
i_return = 0xb1,
i_getstatic = 0xb2,
i_putstatic = 0xb3,
i_getfield = 0xb4,
i_putfield = 0xb5,
i_invokevirtual = 0xb6,
i_invokespecial = 0xb7,
i_invokestatic = 0xb8,
i_invokedynamic = 0xba,
i_new = 0xbb,
i_newarray = 0xbc,
i_anewarray = 0xbd,
i_multianewarray = 0xc5,
} jvm_opcode_t;
/* TODO: add -cp arg to achieve class path select */
static char *prefix = NULL;
static inline void bipush(stack_frame_t *op_stack,
uint32_t pc,
uint8_t *code_buf)
{
int8_t param = code_buf[pc + 1];
push_byte(op_stack, param);
}
static inline void sipush(stack_frame_t *op_stack,
uint32_t pc,
uint8_t *code_buf)
{
uint8_t param1 = code_buf[pc + 1], param2 = code_buf[pc + 2];
int16_t res = ((param1 << 8) | param2);
push_short(op_stack, res);
}
static inline void iadd(stack_frame_t *op_stack)
{
int32_t op1 = pop_int(op_stack);
int32_t op2 = pop_int(op_stack);
push_int(op_stack, op1 + op2);
}
static inline void isub(stack_frame_t *op_stack)
{
int32_t op1 = pop_int(op_stack);
int32_t op2 = pop_int(op_stack);
push_int(op_stack, op2 - op1);
}
static inline void imul(stack_frame_t *op_stack)
{
int32_t op1 = pop_int(op_stack);
int32_t op2 = pop_int(op_stack);
push_int(op_stack, op1 * op2);
}
static inline void idiv(stack_frame_t *op_stack)
{
int32_t op1 = pop_int(op_stack);
int32_t op2 = pop_int(op_stack);
push_int(op_stack, op2 / op1);
}
static inline void irem(stack_frame_t *op_stack)
{
int32_t op1 = pop_int(op_stack);
int32_t op2 = pop_int(op_stack);
push_int(op_stack, op2 % op1);
}
static inline void ineg(stack_frame_t *op_stack)
{
int32_t op1 = pop_int(op_stack);
push_int(op_stack, -op1);
}
static inline void iconst(stack_frame_t *op_stack, uint8_t current)
{
push_int(op_stack, current - i_iconst_0);
}
/**
* Execute the opcode instructions of a method until it returns.
*
* @param method the method to run
* @param locals the array of local variables, including the method parameters.
* Except for parameters, the locals are uninitialized.
* @param clazz the class file the method belongs to
* @return stack_entry that contain the method return value and its type. Is a
* heap-allocated pointer which should be free from the caller
*
*/
stack_entry_t *execute(method_t *method,
local_variable_t *locals,
class_file_t *clazz)
{
code_t code = method->code;
stack_frame_t *op_stack = malloc(sizeof(stack_frame_t));
init_stack(op_stack, code.max_stack);
/* position at the program to be run */
uint32_t pc = 0;
uint8_t *code_buf = code.code;
int loop_count = 0;
while (pc < code.code_length) {
loop_count += 1;
uint8_t current = code_buf[pc];
/* Reference:
* https://en.wikipedia.org/wiki/Java_bytecode_instruction_listings
*/
switch (current) {
/* Return int from method */
case i_ireturn: {
stack_entry_t *ret = malloc(sizeof(stack_entry_t));
ret->entry.int_value = (int32_t) pop_int(op_stack);
ret->type = STACK_ENTRY_INT;
free(op_stack->store);
free(op_stack);
return ret;
}
/* Return long from method */
case i_lreturn: {
stack_entry_t *ret = malloc(sizeof(stack_entry_t));
ret->entry.long_value = (int64_t) pop_int(op_stack);
ret->type = STACK_ENTRY_LONG;
free(op_stack->store);
free(op_stack);
return ret;
}
/* Return long from method */
case i_areturn: {
stack_entry_t *ret = malloc(sizeof(stack_entry_t));
ret->entry.ptr_value = pop_ref(op_stack);
ret->type = STACK_ENTRY_REF;
free(op_stack->store);
free(op_stack);
return ret;
}
/* Return void from method */
case i_return: {
stack_entry_t *ret = malloc(sizeof(stack_entry_t));
ret->type = STACK_ENTRY_NONE;
free(op_stack->store);
free(op_stack);
return ret;
}
/* Invoke a class (static) method */
case i_invokestatic: {
uint8_t param1 = code_buf[pc + 1], param2 = code_buf[pc + 2];
uint16_t index = ((param1 << 8) | param2);
/* the method to be called */
char *method_name, *method_descriptor, *class_name;
method_t *own_method = NULL;
class_file_t *target_class = NULL;
/* recursively find method from child to parent */
while (!own_method) {
if (!target_class)
class_name = find_method_info_from_index(
index, clazz, &method_name, &method_descriptor);
else
class_name = find_class_name_from_index(
target_class->info->super_class, target_class);
find_or_add_class_to_heap(class_name, prefix, &target_class);
assert(target_class &&
"Failed to load class in i_invokestatic");
own_method =
find_method(method_name, method_descriptor, target_class);
}
/* call static initialization. Only the class that contains this
* method should do static initialization */
if (!target_class->initialized) {
target_class->initialized = true;
method_t *method = find_method("<clinit>", "()V", target_class);
if (method) {
local_variable_t own_locals[method->code.max_locals];
stack_entry_t *exec_res =
execute(method, own_locals, target_class);
assert(exec_res->type == STACK_ENTRY_NONE &&
"<clinit> must not return a value");
free(exec_res);
}
}
uint16_t num_params = get_number_of_parameters(own_method);
local_variable_t own_locals[own_method->code.max_locals];
for (int i = num_params - 1; i >= 0; i--)
pop_to_local(op_stack, &own_locals[i]);
stack_entry_t *exec_res =
execute(own_method, own_locals, target_class);
switch (exec_res->type) {
case STACK_ENTRY_INT:
push_int(op_stack, exec_res->entry.int_value);
break;
case STACK_ENTRY_LONG:
push_long(op_stack, exec_res->entry.long_value);
break;
case STACK_ENTRY_REF:
push_ref(op_stack, exec_res->entry.ptr_value);
break;
case STACK_ENTRY_NONE:
/* nothing */
break;
default:
assert(0 && "unknown return type");
}
free(exec_res);
pc += 3;
break;
}
/* Compare long */
case i_lcmp: {
int64_t op1 = pop_int(op_stack), op2 = pop_int(op_stack);
if (op1 < op2) {
push_int(op_stack, 1);
} else if (op1 == op2) {
push_int(op_stack, 0);
} else {
push_int(op_stack, -1);
}
pc += 1;
break;
}
/* Branch if int comparison with zero succeeds: if equals */
case i_ifeq: {
uint8_t param1 = code_buf[pc + 1], param2 = code_buf[pc + 2];
int32_t conditional = pop_int(op_stack);
pc += 3;
if (conditional == 0) {
int16_t res = ((param1 << 8) | param2);
pc += res - 3;
}
break;
}
/* Branch if int comparison with zero succeeds: if not equals */
case i_ifne: {
uint8_t param1 = code_buf[pc + 1], param2 = code_buf[pc + 2];
int32_t conditional = pop_int(op_stack);
pc += 3;
if (conditional != 0) {
int16_t res = ((param1 << 8) | param2);
pc += res - 3;
}
break;
}
/* Branch if int comparison with zero succeeds: if less than 0 */
case i_iflt: {
uint8_t param1 = code_buf[pc + 1], param2 = code_buf[pc + 2];
int32_t conditional = pop_int(op_stack);
pc += 3;
if (conditional < 0) {
int16_t res = ((param1 << 8) | param2);
pc += res - 3;
}
break;
}
/* Branch if int comparison with zero succeeds: if >= 0 */
case i_ifge: {
uint8_t param1 = code_buf[pc + 1], param2 = code_buf[pc + 2];
int32_t conditional = pop_int(op_stack);
pc += 3;
if (conditional >= 0) {
int16_t res = ((param1 << 8) | param2);
pc += res - 3;
}
break;
}
/* Branch if int comparison with zero succeeds: if greater than 0 */
case i_ifgt: {
uint8_t param1 = code_buf[pc + 1], param2 = code_buf[pc + 2];
int32_t conditional = pop_int(op_stack);
pc += 3;
if (conditional > 0) {
int16_t res = ((param1 << 8) | param2);
pc += res - 3;
}
break;
}
/* Branch if int comparison with zero succeeds: if <= 0 */
case i_ifle: {
uint8_t param1 = code_buf[pc + 1], param2 = code_buf[pc + 2];
int32_t conditional = pop_int(op_stack);
pc += 3;
if (conditional <= 0) {
int16_t res = ((param1 << 8) | param2);
pc += res - 3;
}
break;
}
/* Branch if int comparison succeeds: if equals */
case i_if_icmpeq: {
uint8_t param1 = code_buf[pc + 1], param2 = code_buf[pc + 2];
int32_t op1 = pop_int(op_stack), op2 = pop_int(op_stack);
pc += 3;
if (op2 == op1) {
int16_t res = ((param1 << 8) | param2);
pc += res - 3;
}
break;
}
/* Branch if int comparison succeeds: if not equals */
case i_if_icmpne: {
uint8_t param1 = code_buf[pc + 1], param2 = code_buf[pc + 2];
int32_t op1 = pop_int(op_stack), op2 = pop_int(op_stack);
pc += 3;
if (op2 != op1) {
int16_t res = ((param1 << 8) | param2);
pc += res - 3;
}
break;
}
/* Branch if int comparison succeeds: if less than */
case i_if_icmplt: {
uint8_t param1 = code_buf[pc + 1], param2 = code_buf[pc + 2];
int32_t op1 = pop_int(op_stack), op2 = pop_int(op_stack);
pc += 3;
if (op2 < op1) {
int16_t res = ((param1 << 8) | param2);
pc += res - 3;
}
break;
}
/* Branch if int comparison succeeds: if greater than or equal to */
case i_if_icmpge: {
uint8_t param1 = code_buf[pc + 1], param2 = code_buf[pc + 2];
int32_t op1 = pop_int(op_stack), op2 = pop_int(op_stack);
pc += 3;
if (op2 >= op1) {
int16_t res = ((param1 << 8) | param2);
pc += res - 3;
}
break;
}
/* Branch if int comparison succeeds: if greater than */
case i_if_icmpgt: {
uint8_t param1 = code_buf[pc + 1], param2 = code_buf[pc + 2];
int32_t op1 = pop_int(op_stack), op2 = pop_int(op_stack);
pc += 3;
if (op2 > op1) {
int16_t res = ((param1 << 8) | param2);
pc += res - 3;
}
break;
}
/* Branch if int comparison succeeds: if less than or equal to */
case i_if_icmple: {
uint8_t param1 = code_buf[pc + 1], param2 = code_buf[pc + 2];
int32_t op1 = pop_int(op_stack), op2 = pop_int(op_stack);
pc += 3;
if (op2 <= op1) {
int16_t res = ((param1 << 8) | param2);
pc += res - 3;
}
break;
}
/* Branch always */
case i_goto: {
uint8_t param1 = code_buf[pc + 1], param2 = code_buf[pc + 2];
int16_t res = ((param1 << 8) | param2);
pc += res;
break;
}
/* Push item from run-time constant pool */
case i_ldc: {
constant_pool_t constant_pool = clazz->constant_pool;
/* find the parameter which will be the index from which we retrieve
* constant in the constant pool.
*/
int16_t param = code_buf[pc + 1];
const_pool_info *info = get_constant(&constant_pool, param);
switch (info->tag) {
case CONSTANT_Integer: {
push_int(op_stack,
((CONSTANT_Integer_info *) info->info)->bytes);
break;
}
case CONSTANT_String: {
char *src =
(char *) get_constant(
&constant_pool,
((CONSTANT_String_info *) info->info)->string_index)
->info;
char *dest = create_string(clazz, src);
push_ref(op_stack, dest);
break;
}
default:
assert(0 && "ldc only support int and string");
break;
}
pc += 2;
break;
}
/* Push long or double from run-time constant pool (wide index) */
case i_ldc2_w: {
uint8_t param1 = code_buf[pc + 1], param2 = code_buf[pc + 2];
uint16_t index = ((param1 << 8) | param2);
uint64_t high = ((CONSTANT_LongOrDouble_info *) get_constant(
&clazz->constant_pool, index)
->info)
->high_bytes;
uint64_t low = ((CONSTANT_LongOrDouble_info *) get_constant(
&clazz->constant_pool, index)
->info)
->low_bytes;
int64_t value = high << 32 | low;
push_long(op_stack, value);
pc += 3;
break;
}
/* Load long from local variable */
case i_lload: {
int32_t param = code_buf[pc + 1];
int64_t loaded;
loaded = locals[param].entry.long_value;
push_long(op_stack, loaded);
pc += 2;
break;
}
/* Load int from an array */
case i_iaload: {
int64_t idx = pop_int(op_stack);
int32_t *arr = pop_ref(op_stack);
push_int(op_stack, arr[idx]);
pc += 1;
break;
}
/* Load long from an array */
case i_laload: {
int64_t idx = pop_int(op_stack);
int64_t *arr = pop_ref(op_stack);
push_int(op_stack, arr[idx]);
pc += 1;
break;
}
/* Load reference from array */
case i_aaload: {
int64_t index = pop_int(op_stack);
void **addr = pop_ref(op_stack);
push_ref(op_stack, *(addr + index));
pc += 1;
break;
}
/* Load byte/char from an array */
case i_baload:
case i_caload: {
int64_t idx = pop_int(op_stack);
int8_t *arr = pop_ref(op_stack);
push_int(op_stack, arr[idx]);
pc += 1;
break;
}
/* Load short from an array */
case i_saload: {
int64_t idx = pop_int(op_stack);
int16_t *arr = pop_ref(op_stack);
push_int(op_stack, arr[idx]);
pc += 1;
break;
}
/* FIXME: this implementation has some bugs.
* In standard JVM, one stack entry only store four
* bytes data, so in some method descriptor (e.g (JJ)V)
* the long value will store in locals[0] and locals[2]
* rather than locals[0] and locals[1].
*/
/* Load long from local variable */
case i_lload_0:
case i_lload_1:
case i_lload_2:
case i_lload_3: {
int64_t param = current - i_lload_0;
int64_t loaded;
loaded = locals[param].entry.long_value;
push_long(op_stack, loaded);
pc += 1;
break;
}
/* Load object from local variable */
case i_aload: {
int32_t param = code_buf[pc + 1];
object_t *obj = locals[param].entry.ptr_value;
push_ref(op_stack, obj);
pc += 2;
} break;
/* Load object from local variable */
case i_aload_0:
case i_aload_1:
case i_aload_2:
case i_aload_3: {
int32_t param = current - i_aload_0;
object_t *obj = locals[param].entry.ptr_value;
push_ref(op_stack, obj);
pc += 1;
break;
}
/* Load int from local variable */
case i_iload_0:
case i_iload_1:
case i_iload_2:
case i_iload_3: {
int32_t param = current - i_iload_0;
int32_t loaded;
loaded = locals[param].entry.int_value;
push_int(op_stack, loaded);
pc += 1;
break;
}
/* Load int from local variable */
case i_iload: {
int32_t param = code_buf[pc + 1];
int32_t loaded;
loaded = locals[param].entry.int_value;
push_int(op_stack, loaded);
pc += 2;
break;
}
/* Store long into local variable */
case i_lstore: {
int32_t param = code_buf[pc + 1];
int64_t stored = pop_int(op_stack);
locals[param].entry.long_value = stored;
locals[param].type = STACK_ENTRY_LONG;
pc += 2;
break;
}
/* Store object from local variable */
case i_astore: {
int32_t param = code_buf[pc + 1];
locals[param].entry.ptr_value = pop_ref(op_stack);
locals[param].type = STACK_ENTRY_REF;
pc += 2;
break;
}
/* Store into int array */
case i_iastore: {
int32_t value = pop_int(op_stack);
int64_t idx = pop_int(op_stack);
int32_t *arr = pop_ref(op_stack);
arr[idx] = value;
pc += 1;
break;
}
/* Store into long array */
case i_lastore: {
int64_t value = pop_int(op_stack);
int64_t idx = pop_int(op_stack);
int64_t *arr = pop_ref(op_stack);
arr[idx] = value;
pc += 1;
break;
}
/* Store into reference array */
case i_aastore: {
void *value = pop_ref(op_stack);
int64_t idx = pop_int(op_stack);
void **arr = pop_ref(op_stack);
arr[idx] = value;
pc += 1;
break;
}
/* Store int byte/char array */
case i_bastore:
case i_castore: {
int64_t value = pop_int(op_stack);
int64_t idx = pop_int(op_stack);
int8_t *arr = pop_ref(op_stack);
arr[idx] = value;
pc += 1;
break;
}
/* Store into short array */
case i_sastore: {
int64_t value = pop_int(op_stack);
int64_t idx = pop_int(op_stack);
int16_t *arr = pop_ref(op_stack);
arr[idx] = value;
pc += 1;
break;
}
/* Store long into local variable */
case i_lstore_0:
case i_lstore_1:
case i_lstore_2:
case i_lstore_3: {
int32_t param = current - i_lstore_0;
int64_t stored = pop_int(op_stack);
locals[param].entry.long_value = stored;
locals[param].type = STACK_ENTRY_LONG;
pc += 1;
break;
}
/* Store int into local variable */
case i_istore: {
int32_t param = code_buf[pc + 1];
int32_t stored = pop_int(op_stack);
locals[param].entry.int_value = stored;
locals[param].type = STACK_ENTRY_INT;
pc += 2;
break;
}
/* Store int into local variable */
case i_istore_0:
case i_istore_1:
case i_istore_2:
case i_istore_3: {
int32_t param = current - i_istore_0;
int32_t stored = pop_int(op_stack);
locals[param].entry.int_value = stored;
locals[param].type = STACK_ENTRY_INT;
pc += 1;
break;
}
/* Store object from local variable */
case i_astore_0:
case i_astore_1:
case i_astore_2:
case i_astore_3: {
int32_t param = current - i_astore_0;
locals[param].entry.ptr_value = pop_ref(op_stack);
locals[param].type = STACK_ENTRY_REF;
pc += 1;
break;
}
/* discard the top value on the stack */
case i_pop: {
op_stack->size--;
pc += 1;
break;
}
/* duplicate the value on top of the stack */
case i_dup: {
op_stack->store[op_stack->size] =
op_stack->store[op_stack->size - 1];
op_stack->size++;
pc += 1;
break;
}
/* Increment local variable by constant */
case i_iinc: {
uint8_t i = code_buf[pc + 1];
int8_t b = code_buf[pc + 2]; /* signed value */
locals[i].entry.int_value += b;
pc += 3;
break;
}
/* Convert int to long */
case i_i2l: {
int32_t stored = pop_int(op_stack);
push_long(op_stack, (int64_t) stored);
pc += 1;
break;
}
/* Convert int to char */
case i_l2i: {
int64_t stored = pop_int(op_stack);
push_int(op_stack, (int32_t) stored);
pc += 1;
break;
}
/* Push byte */
case i_bipush:
bipush(op_stack, pc, code_buf);
pc += 2;
break;
/* Add int */
case i_iadd:
iadd(op_stack);
pc += 1;
break;
/* Add long */
case i_ladd: {
int64_t op1 = pop_int(op_stack);
int64_t op2 = pop_int(op_stack);
push_long(op_stack, op1 + op2);
pc += 1;
break;
}
/* Subtract int */
case i_isub:
isub(op_stack);
pc += 1;
break;
/* Subtract long */
case i_lsub: {
int64_t op1 = pop_int(op_stack);
int64_t op2 = pop_int(op_stack);
push_long(op_stack, op2 - op1);
pc += 1;
break;
}
/* Multiply int */
case i_imul:
imul(op_stack);
pc += 1;
break;
/* Multiply long */
case i_lmul: {
int64_t op1 = pop_int(op_stack);
int64_t op2 = pop_int(op_stack);
push_long(op_stack, op1 * op2);
pc += 1;
break;
}
/* Divide int */
case i_idiv:
idiv(op_stack);
pc += 1;
break;
/* Divide long */
case i_ldiv: {
int64_t op1 = pop_int(op_stack);
int64_t op2 = pop_int(op_stack);
push_long(op_stack, op2 / op1);
pc += 1;
break;
}
/* Remainder int */
case i_irem:
irem(op_stack);
pc += 1;
break;
/* Remainder long */
case i_lrem: {
int64_t op1 = pop_int(op_stack);
int64_t op2 = pop_int(op_stack);
push_long(op_stack, op2 % op1);
pc += 1;
break;
}
/* Negate int */
case i_ineg:
ineg(op_stack);
pc += 1;
break;
/* Get static field from class */
case i_getstatic: {
uint8_t param1 = code_buf[pc + 1], param2 = code_buf[pc + 2];
uint16_t index = ((param1 << 8) | param2);
char *field_name, *field_descriptor, *class_name;
field_t *field = NULL;
class_file_t *target_class = NULL;
class_name = find_field_info_from_index(index, clazz, &field_name,
&field_descriptor);
/* skip java.lang.System in order to support java print
* method */
if (!strcmp(class_name, "java/lang/System")) {
pc += 3;
break;
}
while (!field) {
if (target_class)
class_name = find_class_name_from_index(
target_class->info->super_class, target_class);
find_or_add_class_to_heap(class_name, prefix, &target_class);
assert(target_class && "Failed to load class in i_getstatic");
field = find_field(field_name, field_descriptor, target_class);
}
/* call static initialization. Only the class that contains this
* field should do static initialization */
if (!target_class->initialized) {
target_class->initialized = true;
method_t *method = find_method("<clinit>", "()V", target_class);
if (method) {
local_variable_t own_locals[method->code.max_locals];
stack_entry_t *exec_res =
execute(method, own_locals, target_class);
assert(exec_res->type == STACK_ENTRY_NONE &&
"<clinit> must not return a value");
free(exec_res);
}
}
switch (field_descriptor[0]) {
case 'B':
/* signed byte */
push_byte(op_stack, field->static_var->value.char_value);