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circuitpython/py/vm.c

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#include <stdio.h>
#include <assert.h>
#include "nlr.h"
#include "misc.h"
#include "mpconfig.h"
#include "qstr.h"
#include "obj.h"
#include "runtime.h"
#include "bc0.h"
#include "bc.h"
// Value stack grows up (this makes it incompatible with native C stack, but
// makes sure that arguments to functions are in natural order arg1..argN
// (Python semantics mandates left-to-right evaluation order, including for
// function arguments). Stack pointer is pre-incremented and points at the
// top element.
// Exception stack also grows up, top element is also pointed at.
// Exception stack unwind reasons (WHY_* in CPython-speak)
// TODO perhaps compress this to RETURN=0, JUMP>0, with number of unwinds
// left to do encoded in the JUMP number
typedef enum {
UNWIND_RETURN = 1,
UNWIND_JUMP,
} mp_unwind_reason_t;
#define DECODE_UINT { \
unum = 0; \
do { \
unum = (unum << 7) + (*ip & 0x7f); \
} while ((*ip++ & 0x80) != 0); \
}
#define DECODE_ULABEL do { unum = (ip[0] | (ip[1] << 8)); ip += 2; } while (0)
#define DECODE_SLABEL do { unum = (ip[0] | (ip[1] << 8)) - 0x8000; ip += 2; } while (0)
#define DECODE_QSTR { \
qst = 0; \
do { \
qst = (qst << 7) + (*ip & 0x7f); \
} while ((*ip++ & 0x80) != 0); \
}
#define PUSH(val) *++sp = (val)
#define POP() (*sp--)
#define TOP() (*sp)
#define SET_TOP(val) *sp = (val)
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, mp_obj_t *ret) {
const byte *ip = code;
// get code info size, and skip line number table
machine_uint_t code_info_size = ip[0] | (ip[1] << 8) | (ip[2] << 16) | (ip[3] << 24);
ip += code_info_size;
// bytecode prelude: state size and exception stack size; 16 bit uints
machine_uint_t n_state = ip[0] | (ip[1] << 8);
machine_uint_t n_exc_stack = ip[2] | (ip[3] << 8);
ip += 4;
// allocate state for locals and stack
mp_obj_t temp_state[10];
mp_obj_t *state = &temp_state[0];
if (n_state > 10) {
state = m_new(mp_obj_t, n_state);
}
mp_obj_t *sp = &state[0] - 1;
// allocate state for exceptions
mp_exc_stack exc_state[4];
mp_exc_stack *exc_stack = &exc_state[0];
if (n_exc_stack > 4) {
exc_stack = m_new(mp_exc_stack, n_exc_stack);
}
mp_exc_stack *exc_sp = &exc_stack[0] - 1;
// init args
for (uint i = 0; i < n_args; i++) {
state[n_state - 1 - i] = args[i];
}
for (uint i = 0; i < n_args2; i++) {
state[n_state - 1 - n_args - i] = args2[i];
}
// bytecode prelude: initialise closed over variables
for (uint n_local = *ip++; n_local > 0; n_local--) {
uint local_num = *ip++;
if (local_num < n_args + n_args2) {
state[n_state - 1 - local_num] = mp_obj_new_cell(state[n_state - 1 - local_num]);
} else {
state[n_state - 1 - local_num] = mp_obj_new_cell(MP_OBJ_NULL);
}
}
// execute the byte code
mp_vm_return_kind_t vm_return_kind = mp_execute_byte_code_2(code, &ip, &state[n_state - 1], &sp, exc_stack, &exc_sp, MP_OBJ_NULL);
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:
// 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,
mp_exc_stack *exc_stack, mp_exc_stack **exc_sp_in_out,
volatile mp_obj_t inject_exc) {
// careful: be sure to declare volatile any variables read in the exception handler (written is ok, I think)
const byte *ip = *ip_in_out;
mp_obj_t *sp = *sp_in_out;
machine_uint_t unum;
qstr qst;
mp_obj_t obj1, obj2;
nlr_buf_t nlr;
volatile bool currently_in_except_block = MP_TAGPTR_TAG(*exc_sp_in_out); // 0 or 1, to detect nested exceptions
mp_exc_stack *volatile exc_sp = MP_TAGPTR_PTR(*exc_sp_in_out); // stack grows up, exc_sp points to top of stack
const byte *volatile save_ip = ip; // this is so we can access ip in the exception handler without making ip volatile (which means the compiler can't keep it in a register in the main loop)
// outer exception handling loop
for (;;) {
outer_dispatch_loop:
if (nlr_push(&nlr) == 0) {
// If we have exception to inject, now that we finish setting up
// execution context, raise it. This works as if RAISE_VARARGS
// bytecode was executed.
if (inject_exc != MP_OBJ_NULL) {
mp_obj_t t = inject_exc;
inject_exc = MP_OBJ_NULL;
nlr_jump(rt_make_raise_obj(t));
}
// loop to execute byte code
for (;;) {
dispatch_loop:
save_ip = ip;
int op = *ip++;
switch (op) {
case MP_BC_LOAD_CONST_FALSE:
PUSH(mp_const_false);
break;
case MP_BC_LOAD_CONST_NONE:
PUSH(mp_const_none);
break;
case MP_BC_LOAD_CONST_TRUE:
PUSH(mp_const_true);
break;
case MP_BC_LOAD_CONST_ELLIPSIS:
PUSH(mp_const_ellipsis);
break;
case MP_BC_LOAD_CONST_SMALL_INT: {
machine_int_t num = 0;
if ((ip[0] & 0x40) != 0) {
// Number is negative
num--;
}
do {
num = (num << 7) | (*ip & 0x7f);
} while ((*ip++ & 0x80) != 0);
PUSH(MP_OBJ_NEW_SMALL_INT(num));
break;
}
case MP_BC_LOAD_CONST_INT:
DECODE_QSTR;
PUSH(mp_obj_new_int_from_long_str(qstr_str(qst)));
break;
case MP_BC_LOAD_CONST_DEC:
DECODE_QSTR;
PUSH(rt_load_const_dec(qst));
break;
case MP_BC_LOAD_CONST_ID:
DECODE_QSTR;
PUSH(rt_load_const_str(qst)); // TODO
break;
case MP_BC_LOAD_CONST_BYTES:
DECODE_QSTR;
PUSH(rt_load_const_bytes(qst));
break;
case MP_BC_LOAD_CONST_STRING:
DECODE_QSTR;
PUSH(rt_load_const_str(qst));
break;
case MP_BC_LOAD_FAST_0:
PUSH(fastn[0]);
break;
case MP_BC_LOAD_FAST_1:
PUSH(fastn[-1]);
break;
case MP_BC_LOAD_FAST_2:
PUSH(fastn[-2]);
break;
case MP_BC_LOAD_FAST_N:
DECODE_UINT;
PUSH(fastn[-unum]);
break;
case MP_BC_LOAD_DEREF:
DECODE_UINT;
PUSH(rt_get_cell(fastn[-unum]));
break;
case MP_BC_LOAD_NAME:
DECODE_QSTR;
PUSH(rt_load_name(qst));
break;
case MP_BC_LOAD_GLOBAL:
DECODE_QSTR;
PUSH(rt_load_global(qst));
break;
case MP_BC_LOAD_ATTR:
DECODE_QSTR;
SET_TOP(rt_load_attr(TOP(), qst));
break;
case MP_BC_LOAD_METHOD:
DECODE_QSTR;
rt_load_method(*sp, qst, sp);
sp += 1;
break;
case MP_BC_LOAD_BUILD_CLASS:
PUSH(rt_load_build_class());
break;
case MP_BC_STORE_FAST_0:
fastn[0] = POP();
break;
case MP_BC_STORE_FAST_1:
fastn[-1] = POP();
break;
case MP_BC_STORE_FAST_2:
fastn[-2] = POP();
break;
case MP_BC_STORE_FAST_N:
DECODE_UINT;
fastn[-unum] = POP();
break;
case MP_BC_STORE_DEREF:
DECODE_UINT;
rt_set_cell(fastn[-unum], POP());
break;
case MP_BC_STORE_NAME:
DECODE_QSTR;
rt_store_name(qst, POP());
break;
case MP_BC_STORE_GLOBAL:
DECODE_QSTR;
rt_store_global(qst, POP());
break;
case MP_BC_STORE_ATTR:
DECODE_QSTR;
rt_store_attr(sp[0], qst, sp[-1]);
sp -= 2;
break;
case MP_BC_STORE_SUBSCR:
rt_store_subscr(sp[-1], sp[0], sp[-2]);
sp -= 3;
break;
case MP_BC_DELETE_NAME:
DECODE_QSTR;
rt_delete_name(qst);
break;
case MP_BC_DUP_TOP:
obj1 = TOP();
PUSH(obj1);
break;
case MP_BC_DUP_TOP_TWO:
sp += 2;
sp[0] = sp[-2];
sp[-1] = sp[-3];
break;
case MP_BC_POP_TOP:
sp -= 1;
break;
case MP_BC_ROT_TWO:
obj1 = sp[0];
sp[0] = sp[-1];
sp[-1] = obj1;
break;
case MP_BC_ROT_THREE:
obj1 = sp[0];
sp[0] = sp[-1];
sp[-1] = sp[-2];
sp[-2] = obj1;
break;
case MP_BC_JUMP:
DECODE_SLABEL;
ip += unum;
break;
case MP_BC_POP_JUMP_IF_TRUE:
DECODE_SLABEL;
if (rt_is_true(POP())) {
ip += unum;
}
break;
case MP_BC_POP_JUMP_IF_FALSE:
DECODE_SLABEL;
if (!rt_is_true(POP())) {
ip += unum;
}
break;
case MP_BC_JUMP_IF_TRUE_OR_POP:
DECODE_SLABEL;
if (rt_is_true(TOP())) {
ip += unum;
} else {
sp--;
}
break;
case MP_BC_JUMP_IF_FALSE_OR_POP:
DECODE_SLABEL;
if (rt_is_true(TOP())) {
sp--;
} else {
ip += unum;
}
break;
/* we are trying to get away without using this opcode
case MP_BC_SETUP_LOOP:
DECODE_UINT;
// push_block(MP_BC_SETUP_LOOP, ip + unum, sp)
break;
*/
case MP_BC_UNWIND_JUMP:
DECODE_SLABEL;
PUSH((void*)(ip + unum)); // push destination ip for jump
PUSH((void*)(machine_uint_t)(*ip)); // push number of exception handlers to unwind
unwind_jump:
unum = (machine_uint_t)POP(); // get number of exception handlers to unwind
while (unum > 0) {
unum -= 1;
assert(exc_sp >= exc_stack);
if (exc_sp->opcode == MP_BC_SETUP_FINALLY) {
// We're going to run "finally" code as a coroutine
// (not calling it recursively). Set up a sentinel
// on a stack so it can return back to us when it is
// done (when END_FINALLY reached).
PUSH((void*)unum); // push number of exception handlers left to unwind
PUSH(MP_OBJ_NEW_SMALL_INT(UNWIND_JUMP)); // push sentinel
ip = exc_sp->handler; // get exception handler byte code address
exc_sp--; // pop exception handler
goto dispatch_loop; // run the exception handler
}
exc_sp--;
}
ip = (const byte*)POP(); // pop destination ip for jump
break;
// matched against: POP_BLOCK or POP_EXCEPT (anything else?)
case MP_BC_SETUP_EXCEPT:
case MP_BC_SETUP_FINALLY:
DECODE_ULABEL; // except labels are always forward
++exc_sp;
exc_sp->opcode = op;
exc_sp->handler = ip + unum;
exc_sp->val_sp = MP_TAGPTR_MAKE(sp, currently_in_except_block);
currently_in_except_block = 0; // in a try block now
break;
case MP_BC_END_FINALLY:
// not fully implemented
// if TOS is an exception, reraises the exception (3 values on TOS)
// if TOS is None, just pops it and continues
// if TOS is an integer, does something else
// else error
if (mp_obj_is_exception_instance(TOP())) {
nlr_jump(TOP());
}
if (TOP() == mp_const_none) {
sp--;
} else if (MP_OBJ_IS_SMALL_INT(TOP())) {
// We finished "finally" coroutine and now dispatch back
// to our caller, based on TOS value
mp_unwind_reason_t reason = MP_OBJ_SMALL_INT_VALUE(POP());
switch (reason) {
case UNWIND_RETURN:
goto unwind_return;
case UNWIND_JUMP:
goto unwind_jump;
}
assert(0);
} else {
assert(0);
}
break;
case MP_BC_GET_ITER:
SET_TOP(rt_getiter(TOP()));
break;
case MP_BC_FOR_ITER:
DECODE_ULABEL; // the jump offset if iteration finishes; for labels are always forward
obj1 = rt_iternext_allow_raise(TOP());
if (obj1 == MP_OBJ_NULL) {
--sp; // pop the exhausted iterator
ip += unum; // jump to after for-block
} else {
PUSH(obj1); // push the next iteration value
}
break;
// matched against: SETUP_EXCEPT, SETUP_FINALLY, SETUP_WITH
case MP_BC_POP_BLOCK:
// we are exiting an exception handler, so pop the last one of the exception-stack
assert(exc_sp >= exc_stack);
currently_in_except_block = MP_TAGPTR_TAG(exc_sp->val_sp); // restore previous state
exc_sp--; // pop back to previous exception handler
break;
// matched against: SETUP_EXCEPT
case MP_BC_POP_EXCEPT:
// TODO need to work out how blocks work etc
// pops block, checks it's an exception block, and restores the stack, saving the 3 exception values to local threadstate
assert(exc_sp >= exc_stack);
assert(currently_in_except_block);
//sp = (mp_obj_t*)(*exc_sp--);
//exc_sp--; // discard ip
currently_in_except_block = MP_TAGPTR_TAG(exc_sp->val_sp); // restore previous state
exc_sp--; // pop back to previous exception handler
//sp -= 3; // pop 3 exception values
break;
case MP_BC_NOT:
if (TOP() == mp_const_true) {
SET_TOP(mp_const_false);
} else {
SET_TOP(mp_const_true);
}
break;
case MP_BC_UNARY_OP:
unum = *ip++;
SET_TOP(rt_unary_op(unum, TOP()));
break;
case MP_BC_BINARY_OP:
unum = *ip++;
obj2 = POP();
obj1 = TOP();
SET_TOP(rt_binary_op(unum, obj1, obj2));
break;
case MP_BC_BUILD_TUPLE:
DECODE_UINT;
sp -= unum - 1;
SET_TOP(rt_build_tuple(unum, sp));
break;
case MP_BC_BUILD_LIST:
DECODE_UINT;
sp -= unum - 1;
SET_TOP(rt_build_list(unum, sp));
break;
case MP_BC_LIST_APPEND:
DECODE_UINT;
// I think it's guaranteed by the compiler that sp[unum] is a list
rt_list_append(sp[-unum], sp[0]);
sp--;
break;
case MP_BC_BUILD_MAP:
DECODE_UINT;
PUSH(rt_build_map(unum));
break;
case MP_BC_STORE_MAP:
sp -= 2;
rt_store_map(sp[0], sp[2], sp[1]);
break;
case MP_BC_MAP_ADD:
DECODE_UINT;
// I think it's guaranteed by the compiler that sp[-unum - 1] is a map
rt_store_map(sp[-unum - 1], sp[0], sp[-1]);
sp -= 2;
break;
case MP_BC_BUILD_SET:
DECODE_UINT;
sp -= unum - 1;
SET_TOP(rt_build_set(unum, sp));
break;
case MP_BC_SET_ADD:
DECODE_UINT;
// I think it's guaranteed by the compiler that sp[-unum] is a set
rt_store_set(sp[-unum], sp[0]);
sp--;
break;
#if MICROPY_ENABLE_SLICE
case MP_BC_BUILD_SLICE:
DECODE_UINT;
if (unum == 2) {
obj2 = POP();
obj1 = TOP();
SET_TOP(mp_obj_new_slice(obj1, obj2, NULL));
} else {
printf("3-argument slice is not supported\n");
assert(0);
}
break;
#endif
case MP_BC_UNPACK_SEQUENCE:
DECODE_UINT;
rt_unpack_sequence(sp[0], unum, sp);
sp += unum - 1;
break;
case MP_BC_MAKE_FUNCTION:
DECODE_UINT;
PUSH(rt_make_function_from_id(unum, MP_OBJ_NULL));
break;
case MP_BC_MAKE_FUNCTION_DEFARGS:
DECODE_UINT;
SET_TOP(rt_make_function_from_id(unum, TOP()));
break;
case MP_BC_MAKE_CLOSURE:
DECODE_UINT;
SET_TOP(rt_make_closure_from_id(unum, TOP(), MP_OBJ_NULL));
break;
case MP_BC_MAKE_CLOSURE_DEFARGS:
DECODE_UINT;
obj1 = POP();
SET_TOP(rt_make_closure_from_id(unum, obj1, TOP()));
break;
case MP_BC_CALL_FUNCTION:
DECODE_UINT;
// unum & 0xff == n_positional
// (unum >> 8) & 0xff == n_keyword
sp -= (unum & 0xff) + ((unum >> 7) & 0x1fe);
SET_TOP(rt_call_function_n_kw(*sp, unum & 0xff, (unum >> 8) & 0xff, sp + 1));
break;
case MP_BC_CALL_METHOD:
DECODE_UINT;
// unum & 0xff == n_positional
// (unum >> 8) & 0xff == n_keyword
sp -= (unum & 0xff) + ((unum >> 7) & 0x1fe) + 1;
SET_TOP(rt_call_method_n_kw(unum & 0xff, (unum >> 8) & 0xff, sp));
break;
case MP_BC_RETURN_VALUE:
unwind_return:
while (exc_sp >= exc_stack) {
if (exc_sp->opcode == MP_BC_SETUP_FINALLY) {
// We're going to run "finally" code as a coroutine
// (not calling it recursively). Set up a sentinel
// on a stack so it can return back to us when it is
// done (when END_FINALLY reached).
PUSH(MP_OBJ_NEW_SMALL_INT(UNWIND_RETURN));
ip = exc_sp->handler;
// We don't need to do anything with sp, finally is just
// syntactic sugar for sequential execution??
// sp =
exc_sp--;
goto dispatch_loop;
}
exc_sp--;
}
nlr_pop();
*sp_in_out = sp;
assert(exc_sp == exc_stack - 1);
return MP_VM_RETURN_NORMAL;
case MP_BC_RAISE_VARARGS:
unum = *ip++;
assert(unum <= 1);
if (unum == 0) {
// This assumes that nlr.ret_val holds last raised
// exception and is not overwritten since then.
obj1 = nlr.ret_val;
} else {
obj1 = POP();
}
nlr_jump(rt_make_raise_obj(obj1));
case MP_BC_YIELD_VALUE:
nlr_pop();
*ip_in_out = ip;
*sp_in_out = sp;
*exc_sp_in_out = MP_TAGPTR_MAKE(exc_sp, currently_in_except_block);
return MP_VM_RETURN_YIELD;
case MP_BC_IMPORT_NAME:
DECODE_QSTR;
obj1 = POP();
SET_TOP(rt_import_name(qst, obj1, TOP()));
break;
case MP_BC_IMPORT_FROM:
DECODE_QSTR;
obj1 = rt_import_from(TOP(), qst);
PUSH(obj1);
break;
case MP_BC_IMPORT_STAR:
rt_import_all(POP());
break;
default:
printf("code %p, byte code 0x%02x not implemented\n", ip, op);
assert(0);
nlr_pop();
return MP_VM_RETURN_NORMAL;
}
}
} else {
// exception occurred
// check if it's a StopIteration within a for block
if (*save_ip == MP_BC_FOR_ITER && mp_obj_is_subclass_fast(mp_obj_get_type(nlr.ret_val), &mp_type_StopIteration)) {
ip = save_ip + 1;
DECODE_ULABEL; // the jump offset if iteration finishes; for labels are always forward
--sp; // pop the exhausted iterator
ip += unum; // jump to after for-block
goto outer_dispatch_loop; // continue with dispatch loop
}
// set file and line number that the exception occurred at
// TODO: don't set traceback for exceptions re-raised by END_FINALLY.
// But consider how to handle nested exceptions.
if (mp_obj_is_exception_instance(nlr.ret_val)) {
machine_uint_t code_info_size = code_info[0] | (code_info[1] << 8) | (code_info[2] << 16) | (code_info[3] << 24);
qstr source_file = code_info[4] | (code_info[5] << 8) | (code_info[6] << 16) | (code_info[7] << 24);
qstr block_name = code_info[8] | (code_info[9] << 8) | (code_info[10] << 16) | (code_info[11] << 24);
machine_uint_t source_line = 1;
machine_uint_t bc = save_ip - code_info - code_info_size;
//printf("find %lu %d %d\n", bc, code_info[12], code_info[13]);
for (const byte* ci = code_info + 12; *ci && bc >= ((*ci) & 31); ci++) {
bc -= *ci & 31;
source_line += *ci >> 5;
}
mp_obj_exception_add_traceback(nlr.ret_val, source_file, source_line, block_name);
}
while (currently_in_except_block) {
// nested exception
assert(exc_sp >= exc_stack);
// TODO make a proper message for nested exception
// at the moment we are just raising the very last exception (the one that caused the nested exception)
// move up to previous exception handler
currently_in_except_block = MP_TAGPTR_TAG(exc_sp->val_sp); // restore previous state
exc_sp--; // pop back to previous exception handler
}
if (exc_sp >= exc_stack) {
// set flag to indicate that we are now handling an exception
currently_in_except_block = 1;
// catch exception and pass to byte code
sp = MP_TAGPTR_PTR(exc_sp->val_sp);
ip = exc_sp->handler;
// push(traceback, exc-val, exc-type)
PUSH(mp_const_none);
PUSH(nlr.ret_val);
PUSH(nlr.ret_val); // TODO should be type(nlr.ret_val), I think...
} else {
// 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;
}
}
}
}
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