Lerking/micropython
1
0
Fork 0
mirror of https://github.com/micropython/micropython.git synced 2026-01-06 12:10:13 +01:00
Code Issues Actions 27 Packages Projects Releases Wiki Activity

py: Fix compiling and decoding of *args at large arg positions.

Browse Source 
There were two issues with the existing code:

1. "1 << i" is computed as a 32-bit number so would overflow when
   executed on 64-bit machines (when mp_uint_t is 64-bit).  This meant that
   *args beyond 32 positions would not be handled correctly.

2. star_args must fit as a positive small int so that it is encoded
   correctly in the emitted code.  MP_SMALL_INT_BITS is too big because it
   overflows a small int by 1 bit.  MP_SMALL_INT_BITS - 1 does not work
   because it produces a signed small int which is then sign extended when
   extracted (even by mp_obj_get_int_truncated), and this sign extension
   means that any position arg after *args is also treated as a star-arg.
   So the maximum bit position is MP_SMALL_INT_BITS - 2.  This means that
   MP_OBJ_SMALL_INT_VALUE() can be used instead of
   mp_obj_get_int_truncated() to get the value of star_args.

These issues are fixed by this commit, and a test added.

Signed-off-by: Damien George <damien@micropython.org>
This commit is contained in:
Damien George
2022-04-01 00:00:58 +11:00
parent e3de723e2d
commit bd556b6996
4 changed files with 44 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
py/runtime.c
View File

@@ -702,7 +702,7 @@ void mp_call_prepare_args_n_kw_var(bool have_self, size_t n_args_n_kw, const mp_
}
size_t n_args = n_args_n_kw & 0xff;
size_t n_kw = (n_args_n_kw >> 8) & 0xff;
mp_uint_t star_args = mp_obj_get_int_truncated(args[n_args + 2 * n_kw]);
mp_uint_t star_args = MP_OBJ_SMALL_INT_VALUE(args[n_args + 2 * n_kw]);
DEBUG_OP_printf("call method var (fun=%p, self=%p, n_args=%u, n_kw=%u, args=%p, map=%u)\n", fun, self, n_args, n_kw, args, star_args);
@@ -720,7 +720,7 @@ void mp_call_prepare_args_n_kw_var(bool have_self, size_t n_args_n_kw, const mp_
if (star_args != 0) {
for (size_t i = 0; i < n_args; i++) {
if (star_args & (1 << i)) {
if ((star_args >> i) & 1) {
mp_obj_t len = mp_obj_len_maybe(args[i]);
if (len != MP_OBJ_NULL) {
// -1 accounts for 1 of n_args occupied by this arg
@@ -773,7 +773,7 @@ void mp_call_prepare_args_n_kw_var(bool have_self, size_t n_args_n_kw, const mp_
for (size_t i = 0; i < n_args; i++) {
mp_obj_t arg = args[i];
if (star_args & (1 << i)) {
if ((star_args >> i) & 1) {
// star arg
if (mp_obj_is_type(arg, &mp_type_tuple) || mp_obj_is_type(arg, &mp_type_list)) {
// optimise the case of a tuple and list