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access dk_indices through a union

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benjaminp committed Sep 8, 2016
1 parent a4348cc commit 186122ead26f3ae4c2bc9f6715d2a29d339fdc5a
Showing with 18 additions and 17 deletions.
  1. +6 −1 Objects/dict-common.h
  2. +12 −16 Objects/dictobject.c
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@@ -62,7 +62,12 @@ struct _dictkeysobject {
- 8 bytes otherwise (Py_ssize_t*)
Dynamically sized, 8 is minimum. */
char dk_indices[8];
union {
int8_t as_1[8];
int16_t as_2[4];
int32_t as_4[2];
int64_t as_8[1];
} dk_indices;
/* "PyDictKeyEntry dk_entries[dk_usable];" array follows:
see the DK_ENTRIES() macro */
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@@ -293,7 +293,7 @@ PyDict_Fini(void)
2 : sizeof(Py_ssize_t))
#endif
#define DK_ENTRIES(dk) \
((PyDictKeyEntry*)(&(dk)->dk_indices[DK_SIZE(dk) * DK_IXSIZE(dk)]))
((PyDictKeyEntry*)(&(dk)->dk_indices.as_1[DK_SIZE(dk) * DK_IXSIZE(dk)]))
#define DK_DEBUG_INCREF _Py_INC_REFTOTAL _Py_REF_DEBUG_COMMA
#define DK_DEBUG_DECREF _Py_DEC_REFTOTAL _Py_REF_DEBUG_COMMA
@@ -312,21 +312,19 @@ dk_get_index(PyDictKeysObject *keys, Py_ssize_t i)
Py_ssize_t ix;
if (s <= 0xff) {
char *indices = (char*)keys->dk_indices;
int8_t *indices = keys->dk_indices.as_1;
ix = indices[i];
}
else if (s <= 0xffff) {
int16_t *indices = (int16_t*)keys->dk_indices;
int16_t *indices = keys->dk_indices.as_2;
ix = indices[i];
}
#if SIZEOF_VOID_P > 4
else if (s <= 0xffffffff) {
int32_t *indices = (int32_t*)keys->dk_indices;
int32_t *indices = keys->dk_indices.as_4;
ix = indices[i];
}
#endif
else {
Py_ssize_t *indices = (Py_ssize_t*)keys->dk_indices;
int64_t *indices = keys->dk_indices.as_8;
ix = indices[i];
}
assert(ix >= DKIX_DUMMY);
@@ -342,24 +340,22 @@ dk_set_index(PyDictKeysObject *keys, Py_ssize_t i, Py_ssize_t ix)
assert(ix >= DKIX_DUMMY);
if (s <= 0xff) {
char *indices = (char*)keys->dk_indices;
int8_t *indices = keys->dk_indices.as_1;
assert(ix <= 0x7f);
indices[i] = (char)ix;
}
else if (s <= 0xffff) {
int16_t *indices = (int16_t*)keys->dk_indices;
int16_t *indices = keys->dk_indices.as_2;
assert(ix <= 0x7fff);
indices[i] = (int16_t)ix;
}
#if SIZEOF_VOID_P > 4
else if (s <= 0xffffffff) {
int32_t *indices = (int32_t*)keys->dk_indices;
int32_t *indices = keys->dk_indices.as_4;
assert(ix <= 0x7fffffff);
indices[i] = (int32_t)ix;
}
#endif
else {
Py_ssize_t *indices = (Py_ssize_t*)keys->dk_indices;
int64_t *indices = keys->dk_indices.as_8;
indices[i] = ix;
}
}
@@ -418,8 +414,8 @@ static PyDictKeysObject empty_keys_struct = {
lookdict_split, /* dk_lookup */
0, /* dk_usable (immutable) */
0, /* dk_nentries */
{DKIX_EMPTY, DKIX_EMPTY, DKIX_EMPTY, DKIX_EMPTY,
DKIX_EMPTY, DKIX_EMPTY, DKIX_EMPTY, DKIX_EMPTY}, /* dk_indices */
.dk_indices = { .as_1 = {DKIX_EMPTY, DKIX_EMPTY, DKIX_EMPTY, DKIX_EMPTY,
DKIX_EMPTY, DKIX_EMPTY, DKIX_EMPTY, DKIX_EMPTY}},
};
static PyObject *empty_values[1] = { NULL };
@@ -468,7 +464,7 @@ static PyDictKeysObject *new_keys_object(Py_ssize_t size)
dk->dk_usable = usable;
dk->dk_lookup = lookdict_unicode_nodummy;
dk->dk_nentries = 0;
memset(&dk->dk_indices[0], 0xff, es * size);
memset(&dk->dk_indices.as_1[0], 0xff, es * size);
memset(DK_ENTRIES(dk), 0, sizeof(PyDictKeyEntry) * usable);
return dk;
}

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