diff options
author | Damien George <damien@micropython.org> | 2022-06-08 14:43:02 +1000 |
---|---|---|
committer | Damien George <damien@micropython.org> | 2022-06-08 14:59:43 +1000 |
commit | cbad5593668fa011a22d0816e27b6f8992ac7015 (patch) | |
tree | 6af358ce30f4febf36e51beee009d532b9b3b70d /py | |
parent | a4eef90b2274d2e34486b6990191687500cb3893 (diff) |
py/compile: Give the compiler a hint about num nodes being non-zero.
Without this, newer versions of gcc (eg 11.2.0) used with -O2 can warn
about `q_ptr` being maybe uninitialized, because it doesn't know that there
is at least one qstr being written in to this (alloca'd) memory.
As part of this, change the type of `n` to `size_t` so the compiler knows
it's unsigned and can generate better code.
Code size change for this commit:
bare-arm: -28 -0.049%
minimal x86: -4 -0.002%
unix x64: +0 +0.000%
unix nanbox: -16 -0.003%
stm32: -24 -0.006% PYBV10
cc3200: -32 -0.017%
esp8266: +8 +0.001% GENERIC
esp32: -52 -0.003% GENERIC
nrf: -24 -0.013% pca10040
rp2: -32 -0.006% PICO
samd: -28 -0.020% ADAFRUIT_ITSYBITSY_M4_EXPRESS
Signed-off-by: Damien George <damien@micropython.org>
Diffstat (limited to 'py')
-rw-r--r-- | py/compile.c | 15 |
1 files changed, 10 insertions, 5 deletions
diff --git a/py/compile.c b/py/compile.c index 4dee9eff7..9cca5df40 100644 --- a/py/compile.c +++ b/py/compile.c @@ -1115,14 +1115,19 @@ STATIC void do_import_name(compiler_t *comp, mp_parse_node_t pn, qstr *q_base) { if (!is_as) { *q_base = MP_PARSE_NODE_LEAF_ARG(pns->nodes[0]); } - int n = MP_PARSE_NODE_STRUCT_NUM_NODES(pns); - int len = n - 1; - for (int i = 0; i < n; i++) { + size_t n = MP_PARSE_NODE_STRUCT_NUM_NODES(pns); + if (n == 0) { + // There must be at least one node in this PN_dotted_name. + // Let the compiler know this so it doesn't warn, and can generate better code. + MP_UNREACHABLE; + } + size_t len = n - 1; + for (size_t i = 0; i < n; i++) { len += qstr_len(MP_PARSE_NODE_LEAF_ARG(pns->nodes[i])); } char *q_ptr = mp_local_alloc(len); char *str_dest = q_ptr; - for (int i = 0; i < n; i++) { + for (size_t i = 0; i < n; i++) { if (i > 0) { *str_dest++ = '.'; } @@ -1135,7 +1140,7 @@ STATIC void do_import_name(compiler_t *comp, mp_parse_node_t pn, qstr *q_base) { mp_local_free(q_ptr); EMIT_ARG(import, q_full, MP_EMIT_IMPORT_NAME); if (is_as) { - for (int i = 1; i < n; i++) { + for (size_t i = 1; i < n; i++) { EMIT_ARG(attr, MP_PARSE_NODE_LEAF_ARG(pns->nodes[i]), MP_EMIT_ATTR_LOAD); } } |