Lephenixnoir
/
PythonExtra
1
0
Fork 2
Code Issues 9 Pull Requests 3 Projects Releases 2 Wiki Activity

py: Remove BITS_PER_WORD definition. 

It's only used in one location, to test if << or >> will overflow when
shifting mp_uint_t.  For such a test it's clearer to use sizeof(lhs_val),
which will be valid even if the type of lhs_val changes.

Signed-off-by: Damien George <damien@micropython.org>
This commit is contained in:
Damien George 2021-02-04 15:27:53 +11:00
parent 7c44354592
commit 8a41ee19c2
2 changed files with 5 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
py/mpconfig.h
View File

@ -1538,7 +1538,6 @@ typedef double mp_float_t;
#ifndef BITS_PER_BYTE
#define BITS_PER_BYTE (8)
#endif
#define BITS_PER_WORD (BITS_PER_BYTE * BYTES_PER_WORD)
// mp_int_t value with most significant bit set
#define WORD_MSBIT_HIGH (((mp_uint_t)1) << (BYTES_PER_WORD * 8 - 1))

8
py/runtime.c
View File

@ -387,7 +387,9 @@ mp_obj_t mp_binary_op(mp_binary_op_t op, mp_obj_t lhs, mp_obj_t rhs) {
if (rhs_val < 0) {
// negative shift not allowed
mp_raise_ValueError(MP_ERROR_TEXT("negative shift count"));
} else if (rhs_val >= (mp_int_t)BITS_PER_WORD || lhs_val > (MP_SMALL_INT_MAX >> rhs_val) || lhs_val < (MP_SMALL_INT_MIN >> rhs_val)) {
} else if (rhs_val >= (mp_int_t)(sizeof(lhs_val) * BITS_PER_BYTE)
|| lhs_val > (MP_SMALL_INT_MAX >> rhs_val)
|| lhs_val < (MP_SMALL_INT_MIN >> rhs_val)) {
// left-shift will overflow, so use higher precision integer
lhs = mp_obj_new_int_from_ll(lhs_val);
goto generic_binary_op;
@ -404,10 +406,10 @@ mp_obj_t mp_binary_op(mp_binary_op_t op, mp_obj_t lhs, mp_obj_t rhs) {
mp_raise_ValueError(MP_ERROR_TEXT("negative shift count"));
} else {
// standard precision is enough for right-shift
if (rhs_val >= (mp_int_t)BITS_PER_WORD) {
if (rhs_val >= (mp_int_t)(sizeof(lhs_val) * BITS_PER_BYTE)) {
// Shifting to big amounts is underfined behavior
// in C and is CPU-dependent; propagate sign bit.
rhs_val = BITS_PER_WORD - 1;
rhs_val = sizeof(lhs_val) * BITS_PER_BYTE - 1;
}
lhs_val >>= rhs_val;
}