void Method::_set_nop()
{
bool verbose = false;
Global_Env *env = VM_Global_State::loader_env;
if (get_name() != env->Init_String || get_descriptor() != env->VoidVoidDescriptor_String) {
return;
}
if(is_native()) {
return;
}
unsigned len = _byte_code_length;
if(!len) {
return;
}
U_8* bc = _byte_codes;
Nop_Stack_State stack_state = NS_StackEmpty;
if(verbose) {
printf("=========== nop[%d]: %s.%s%s\n", len, get_class()->get_name()->bytes, get_name()->bytes, get_descriptor()->bytes);
}
for (unsigned idx = 0; idx < len; idx++) {
U_8 b = bc[idx];
if(verbose) {
printf("\tbc[%d]=%d, state=%d\n", idx, b, stack_state);
}
if(b == 0xb1) { // return
if(verbose) {
printf("+++++++ nop: %s.%s%s\n", get_class()->get_name()->bytes, get_name()->bytes, get_descriptor()->bytes);
}
_flags.is_nop = TRUE;
return;
}
switch(stack_state) {
case NS_StackEmpty:
switch(b) {
case 0x2a: // aload_0
stack_state = NS_ThisPushed;
break;
default:
return;
}
break;
case NS_ThisPushed:
switch(b) {
case 0x01: // aconst_null
case 0x03: // iconst_0
stack_state = NS_ThisAndZeroPushed;
break;
case 0xb7: // invokespecial
{
unsigned index = (bc[idx + 1] << 8) + bc[idx + 2];
if(verbose) {
printf("\tinvokespecial, index=%d\n", index);
}
Method_Handle mh = resolve_special_method_env(VM_Global_State::loader_env,
get_class(),
index, false);
Method *callee = (Method *)mh;
if(!callee) {
if(verbose) {
printf("\tinvokespecial, callee==null\n");
}
return;
}
if(callee == this) {
return;
}
if(verbose) {
printf("invokespecial: %s.%s%s\n", callee->get_class()->get_name()->bytes, callee->get_name()->bytes, callee->get_descriptor()->bytes);
}
if(!callee->is_nop()) {
return;
}
const char *descr = callee->get_descriptor()->bytes;
if(descr[1] != ')') {
return;
}
if(verbose) {
printf("invokespecial nop: %s.%s%s\n", callee->get_class()->get_name()->bytes, callee->get_name()->bytes, callee->get_descriptor()->bytes);
}
}
stack_state = NS_StackEmpty;
idx += 2;
break;
default:
return;
}
break;
case NS_ThisAndZeroPushed:
switch(b) {
case 0xb5: // putfield
stack_state = NS_StackEmpty;
if(verbose) {
printf("\tputfield\n");
}
idx += 2;
break;
default:
return;
}
break;
default:
LDIE(57, "Unexpected stack state");
return;
}
}
LDIE(56, "should'nt get here");
} //Method::_set_nop
//
// resolve constant pool reference to a method
// used for invokespecial
//
Method_Handle resolve_special_method(Compile_Handle h,
Class_Handle c,
unsigned index)
{
return resolve_special_method_env(compile_handle_to_environment(h), c, index, false);
} //resolve_special_method
