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bpo-24700: Add a fast path for comparing array.array of equal type (#3009)

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Adrian Wielgosik 2017-08-17 12:46:06 +00:00 • committed by Antoine Pitrou
parent ee84a60858
commit 7c17e2304b
3 changed files with 78 additions and 15 deletions
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81
Modules/arraymodule.c
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@ -31,6 +31,7 @@ struct arraydescr {
int itemsize;
PyObject * (*getitem)(struct arrayobject *, Py_ssize_t);
int (*setitem)(struct arrayobject *, Py_ssize_t, PyObject *);
int (*compareitems)(const void *, const void *, Py_ssize_t);
const char *formats;
int is_integer_type;
int is_signed;
@ -518,6 +519,28 @@ d_setitem(arrayobject *ap, Py_ssize_t i, PyObject *v)
return 0;
}
#define DEFINE_COMPAREITEMS(code, type) \
static int \
code##_compareitems(const void *lhs, const void *rhs, Py_ssize_t length) \
{ \
const type *a = lhs, *b = rhs; \
for (Py_ssize_t i = 0; i < length; ++i) \
if (a[i] != b[i]) \
return a[i] < b[i] ? -1 : 1; \
return 0; \
}
DEFINE_COMPAREITEMS(b, signed char)
DEFINE_COMPAREITEMS(BB, unsigned char)
DEFINE_COMPAREITEMS(u, Py_UNICODE)
DEFINE_COMPAREITEMS(h, short)
DEFINE_COMPAREITEMS(HH, unsigned short)
DEFINE_COMPAREITEMS(i, int)
DEFINE_COMPAREITEMS(II, unsigned int)
DEFINE_COMPAREITEMS(l, long)
DEFINE_COMPAREITEMS(LL, unsigned long)
DEFINE_COMPAREITEMS(q, long long)
DEFINE_COMPAREITEMS(QQ, unsigned long long)
/* Description of types.
*
@ -525,19 +548,19 @@ d_setitem(arrayobject *ap, Py_ssize_t i, PyObject *v)
* typecode.
*/
static const struct arraydescr descriptors[] = {
{'b', 1, b_getitem, b_setitem, "b", 1, 1},
{'B', 1, BB_getitem, BB_setitem, "B", 1, 0},
{'u', sizeof(Py_UNICODE), u_getitem, u_setitem, "u", 0, 0},
{'h', sizeof(short), h_getitem, h_setitem, "h", 1, 1},
{'H', sizeof(short), HH_getitem, HH_setitem, "H", 1, 0},
{'i', sizeof(int), i_getitem, i_setitem, "i", 1, 1},
{'I', sizeof(int), II_getitem, II_setitem, "I", 1, 0},
{'l', sizeof(long), l_getitem, l_setitem, "l", 1, 1},
{'L', sizeof(long), LL_getitem, LL_setitem, "L", 1, 0},
{'q', sizeof(long long), q_getitem, q_setitem, "q", 1, 1},
{'Q', sizeof(long long), QQ_getitem, QQ_setitem, "Q", 1, 0},
{'f', sizeof(float), f_getitem, f_setitem, "f", 0, 0},
{'d', sizeof(double), d_getitem, d_setitem, "d", 0, 0},
{'b', 1, b_getitem, b_setitem, b_compareitems, "b", 1, 1},
{'B', 1, BB_getitem, BB_setitem, BB_compareitems, "B", 1, 0},
{'u', sizeof(Py_UNICODE), u_getitem, u_setitem, u_compareitems, "u", 0, 0},
{'h', sizeof(short), h_getitem, h_setitem, h_compareitems, "h", 1, 1},
{'H', sizeof(short), HH_getitem, HH_setitem, HH_compareitems, "H", 1, 0},
{'i', sizeof(int), i_getitem, i_setitem, i_compareitems, "i", 1, 1},
{'I', sizeof(int), II_getitem, II_setitem, II_compareitems, "I", 1, 0},
{'l', sizeof(long), l_getitem, l_setitem, l_compareitems, "l", 1, 1},
{'L', sizeof(long), LL_getitem, LL_setitem, LL_compareitems, "L", 1, 0},
{'q', sizeof(long long), q_getitem, q_setitem, q_compareitems, "q", 1, 1},
{'Q', sizeof(long long), QQ_getitem, QQ_setitem, QQ_compareitems, "Q", 1, 0},
{'f', sizeof(float), f_getitem, f_setitem, NULL, "f", 0, 0},
{'d', sizeof(double), d_getitem, d_setitem, NULL, "d", 0, 0},
{'\0', 0, 0, 0, 0, 0, 0} /* Sentinel */
};
@ -664,6 +687,31 @@ array_richcompare(PyObject *v, PyObject *w, int op)
return res;
}
if (va->ob_descr == wa->ob_descr && va->ob_descr->compareitems != NULL) {
/* Fast path:
arrays with same types can have their buffers compared directly */
Py_ssize_t common_length = Py_MIN(Py_SIZE(va), Py_SIZE(wa));
int result = va->ob_descr->compareitems(va->ob_item, wa->ob_item,
common_length);
if (result == 0)
goto compare_sizes;
int cmp;
switch (op) {
case Py_LT: cmp = result < 0; break;
case Py_LE: cmp = result <= 0; break;
case Py_EQ: cmp = result == 0; break;
case Py_NE: cmp = result != 0; break;
case Py_GT: cmp = result > 0; break;
case Py_GE: cmp = result >= 0; break;
default: return NULL; /* cannot happen */
}
PyObject *res = cmp ? Py_True : Py_False;
Py_INCREF(res);
return res;
}
/* Search for the first index where items are different */
k = 1;
for (i = 0; i < Py_SIZE(va) && i < Py_SIZE(wa); i++) {
@ -685,14 +733,17 @@ array_richcompare(PyObject *v, PyObject *w, int op)
if (k) {
/* No more items to compare -- compare sizes */
compare_sizes: ;
Py_ssize_t vs = Py_SIZE(va);
Py_ssize_t ws = Py_SIZE(wa);
int cmp;
switch (op) {
case Py_LT: cmp = vs < ws; break;
case Py_LE: cmp = vs <= ws; break;
case Py_EQ: cmp = vs == ws; break;
case Py_NE: cmp = vs != ws; break;
/* If the lengths were not equal,
the earlier fast-path check would have caught that. */
case Py_EQ: assert(vs == ws); cmp = 1; break;
case Py_NE: assert(vs == ws); cmp = 0; break;
case Py_GT: cmp = vs > ws; break;
case Py_GE: cmp = vs >= ws; break;
default: return NULL; /* cannot happen */