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| author | Damien George <damien@micropython.org> | 2022-04-01 00:00:58 +1100 |
|---|---|---|
| committer | Damien George <damien@micropython.org> | 2022-04-01 09:20:42 +1100 |
| commit | bd556b69960cafc97353e736f825eca5c00b0c29 (patch) | |
| tree | c92422308d39f738ecefeef4fed269b5fde2ddf7 /py/compile.c | |
| parent | e3de723e2d955ca89c8b06bb2c4ae86724aad77b (diff) | |
py: Fix compiling and decoding of *args at large arg positions.
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>
Diffstat (limited to 'py/compile.c')
| -rw-r--r-- | py/compile.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/py/compile.c b/py/compile.c index fc1106270..e4ead7f1a 100644 --- a/py/compile.c +++ b/py/compile.c @@ -2408,9 +2408,9 @@ STATIC void compile_trailer_paren_helper(compiler_t *comp, mp_parse_node_t pn_ar return; } #if MICROPY_DYNAMIC_COMPILER - if (i > mp_dynamic_compiler.small_int_bits) + if (i >= (size_t)mp_dynamic_compiler.small_int_bits - 1) #else - if (i > MP_SMALL_INT_BITS) + if (i >= MP_SMALL_INT_BITS - 1) #endif { // If there are not enough bits in a small int to fit the flag, then we consider @@ -2419,7 +2419,7 @@ STATIC void compile_trailer_paren_helper(compiler_t *comp, mp_parse_node_t pn_ar return; } star_flags |= MP_EMIT_STAR_FLAG_SINGLE; - star_args |= 1 << i; + star_args |= (mp_uint_t)1 << i; compile_node(comp, pns_arg->nodes[0]); n_positional++; } else if (MP_PARSE_NODE_STRUCT_KIND(pns_arg) == PN_arglist_dbl_star) { |