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py: VM never throws an exception, instead returns a status and value.

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Addresses issue #290, and hopefully sets up things to allow generators
throwing exceptions, etc.
This commit is contained in:
Damien George 2014-02-15 22:55:00 +00:00
parent 36109d246f
commit c8f78bc280
6 changed files with 69 additions and 38 deletions
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10
py/bc.h
View file

@ -1,3 +1,9 @@
mp_obj_t mp_execute_byte_code(const byte *code, const mp_obj_t *args, uint n_args, const mp_obj_t *args2, uint n_args2, uint n_state);
bool mp_execute_byte_code_2(const byte *code_info, const byte **ip_in_out, mp_obj_t *fastn, mp_obj_t **sp_in_out);
typedef enum {
MP_VM_RETURN_NORMAL,
MP_VM_RETURN_YIELD,
MP_VM_RETURN_EXCEPTION,
} mp_vm_return_kind_t;
mp_vm_return_kind_t mp_execute_byte_code(const byte *code, const mp_obj_t *args, uint n_args, const mp_obj_t *args2, uint n_args2, uint n_state, mp_obj_t *ret);
mp_vm_return_kind_t mp_execute_byte_code_2(const byte *code_info, const byte **ip_in_out, mp_obj_t *fastn, mp_obj_t **sp_in_out);
void mp_byte_code_print(const byte *code, int len);

3
py/objexcept.c
View file

@ -27,6 +27,7 @@ STATIC void mp_obj_exception_print(void (*print)(void *env, const char *fmt, ...
print(env, "%s: %s", qstr_str(o->base.type->name), vstr_str(o->msg));
} else {
// Yes, that's how CPython has it
// TODO now that exceptions are classes and instances, I think this needs to be changed to match CPython
if (kind == PRINT_REPR) {
print(env, "%s", qstr_str(o->base.type->name));
}
@ -162,7 +163,7 @@ void mp_obj_exception_add_traceback(mp_obj_t self_in, qstr file, machine_uint_t
// for traceback, we are just using the list object for convenience, it's not really a list of Python objects
if (self->traceback == MP_OBJ_NULL) {
self->traceback = mp_obj_new_list(3, NULL);
self->traceback = mp_obj_new_list(0, NULL);
}
mp_obj_list_append(self->traceback, (mp_obj_t)(machine_uint_t)file);
mp_obj_list_append(self->traceback, (mp_obj_t)(machine_uint_t)line);

9
py/objfun.c
View file

@ -152,10 +152,15 @@ STATIC mp_obj_t fun_bc_call(mp_obj_t self_in, uint n_args, uint n_kw, const mp_o
uint use_def_args = self->n_args - n_args;
mp_map_t *old_globals = rt_globals_get();
rt_globals_set(self->globals);
mp_obj_t result = mp_execute_byte_code(self->bytecode, args, n_args, self->def_args + self->n_def_args - use_def_args, use_def_args, self->n_state);
mp_obj_t result;
mp_vm_return_kind_t vm_return_kind = mp_execute_byte_code(self->bytecode, args, n_args, self->def_args + self->n_def_args - use_def_args, use_def_args, self->n_state, &result);
rt_globals_set(old_globals);
return result;
if (vm_return_kind == MP_VM_RETURN_NORMAL) {
return result;
} else { // MP_VM_RETURN_EXCEPTION
nlr_jump(result);
}
}
const mp_obj_type_t fun_bc_type = {

40
py/objgenerator.c
View file

@ -82,22 +82,30 @@ STATIC mp_obj_t gen_next_send(mp_obj_t self_in, mp_obj_t send_value) {
} else {
*self->sp = send_value;
}
bool yield = mp_execute_byte_code_2(self->code_info, &self->ip, &self->state[self->n_state - 1], &self->sp);
if (yield) {
return *self->sp;
} else {
// Explicitly mark generator as completed. If we don't do this,
// subsequent next() may re-execute statements after last yield
// again and again, leading to side effects.
// TODO: check how return with value behaves under such conditions
// in CPython.
self->ip = 0;
if (*self->sp == mp_const_none) {
return mp_const_stop_iteration;
} else {
// TODO return StopIteration with value *self->sp
return mp_const_stop_iteration;
}
mp_vm_return_kind_t vm_return_kind = mp_execute_byte_code_2(self->code_info, &self->ip, &self->state[self->n_state - 1], &self->sp);
switch (vm_return_kind) {
case MP_VM_RETURN_NORMAL:
// Explicitly mark generator as completed. If we don't do this,
// subsequent next() may re-execute statements after last yield
// again and again, leading to side effects.
// TODO: check how return with value behaves under such conditions
// in CPython.
self->ip = 0;
if (*self->sp == mp_const_none) {
return mp_const_stop_iteration;
} else {
// TODO return StopIteration with value *self->sp
return mp_const_stop_iteration;
}
case MP_VM_RETURN_YIELD:
return *self->sp;
case MP_VM_RETURN_EXCEPTION:
default:
// TODO
assert(0);
return mp_const_none;
}
}

43
py/vm.c
View file

@ -47,7 +47,7 @@ typedef enum {
#define TOP() (*sp)
#define SET_TOP(val) *sp = (val)
mp_obj_t mp_execute_byte_code(const byte *code, const mp_obj_t *args, uint n_args, const mp_obj_t *args2, uint n_args2, uint n_state) {
mp_vm_return_kind_t mp_execute_byte_code(const byte *code, const mp_obj_t *args, uint n_args, const mp_obj_t *args2, uint n_args2, uint n_state, mp_obj_t *ret) {
// allocate state for locals and stack
mp_obj_t temp_state[10];
mp_obj_t *state = &temp_state[0];
@ -83,20 +83,30 @@ mp_obj_t mp_execute_byte_code(const byte *code, const mp_obj_t *args, uint n_arg
}
// execute the byte code
if (mp_execute_byte_code_2(code, &ip, &state[n_state - 1], &sp)) {
// it shouldn't yield
assert(0);
}
mp_vm_return_kind_t vm_return_kind = mp_execute_byte_code_2(code, &ip, &state[n_state - 1], &sp);
// TODO check fails if, eg, return from within for loop
//assert(sp == &state[17]);
return *sp;
switch (vm_return_kind) {
case MP_VM_RETURN_NORMAL:
*ret = *sp;
return MP_VM_RETURN_NORMAL;
case MP_VM_RETURN_EXCEPTION:
*ret = state[n_state - 1];
return MP_VM_RETURN_EXCEPTION;
case MP_VM_RETURN_YIELD: // byte-code shouldn't yield
default:
assert(0);
*ret = mp_const_none;
return MP_VM_RETURN_NORMAL;
}
}
// fastn has items in reverse order (fastn[0] is local[0], fastn[-1] is local[1], etc)
// sp points to bottom of stack which grows up
// returns true if bytecode yielded
bool mp_execute_byte_code_2(const byte *code_info, const byte **ip_in_out, mp_obj_t *fastn, mp_obj_t **sp_in_out) {
// returns:
// MP_VM_RETURN_NORMAL, sp valid, return value in *sp
// MP_VM_RETURN_YIELD, ip, sp valid, yielded value in *sp
// MP_VM_RETURN_EXCEPTION, exception in fastn[0]
mp_vm_return_kind_t mp_execute_byte_code_2(const byte *code_info, const byte **ip_in_out, mp_obj_t *fastn, mp_obj_t **sp_in_out) {
// careful: be sure to declare volatile any variables read in the exception handler (written is ok, I think)
const byte *ip = *ip_in_out;
@ -569,7 +579,7 @@ unwind_return:
nlr_pop();
*sp_in_out = sp;
assert(exc_sp == &exc_stack[0] - 1);
return false;
return MP_VM_RETURN_NORMAL;
case MP_BC_RAISE_VARARGS:
unum = *ip++;
@ -581,7 +591,7 @@ unwind_return:
nlr_pop();
*ip_in_out = ip;
*sp_in_out = sp;
return true;
return MP_VM_RETURN_YIELD;
case MP_BC_IMPORT_NAME:
DECODE_QSTR;
@ -603,7 +613,7 @@ unwind_return:
printf("code %p, byte code 0x%02x not implemented\n", ip, op);
assert(0);
nlr_pop();
return false;
return MP_VM_RETURN_NORMAL;
}
}
@ -653,9 +663,10 @@ unwind_return:
PUSH(nlr.ret_val); // TODO should be type(nlr.ret_val), I think...
} else {
// re-raise exception to higher level
// TODO what to do if this is a generator??
nlr_jump(nlr.ret_val);
// propagate exception to higher level
// TODO what to do about ip and sp? they don't really make sense at this point
fastn[0] = nlr.ret_val; // must put exception here because sp is invalid
return MP_VM_RETURN_EXCEPTION;
}
}
}

2
tests/basics/try-module.py
View file

@ -3,7 +3,7 @@
import import1b
def func1():
return
print('func1')
def func2():
try: