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access dk_indices through a union

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This commit is contained in:
Benjamin Peterson 2016-09-08 12:20:12 -07:00
parent a4348cc1be
commit 186122ead2
2 changed files with 18 additions and 17 deletions
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7
Objects/dict-common.h
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@ -62,7 +62,12 @@ struct _dictkeysobject {
- 8 bytes otherwise (Py_ssize_t*) - 8 bytes otherwise (Py_ssize_t*)
Dynamically sized, 8 is minimum. */ 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: /* "PyDictKeyEntry dk_entries[dk_usable];" array follows:
see the DK_ENTRIES() macro */ see the DK_ENTRIES() macro */

28
Objects/dictobject.c
View file

@ -293,7 +293,7 @@ PyDict_Fini(void)
2 : sizeof(Py_ssize_t)) 2 : sizeof(Py_ssize_t))
#endif #endif
#define DK_ENTRIES(dk) \ #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_INCREF _Py_INC_REFTOTAL _Py_REF_DEBUG_COMMA
#define DK_DEBUG_DECREF _Py_DEC_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; Py_ssize_t ix;
if (s <= 0xff) { if (s <= 0xff) {
char *indices = (char*)keys->dk_indices; int8_t *indices = keys->dk_indices.as_1;
ix = indices[i]; ix = indices[i];
} }
else if (s <= 0xffff) { else if (s <= 0xffff) {
int16_t *indices = (int16_t*)keys->dk_indices; int16_t *indices = keys->dk_indices.as_2;
ix = indices[i]; ix = indices[i];
} }
#if SIZEOF_VOID_P > 4
else if (s <= 0xffffffff) { else if (s <= 0xffffffff) {
int32_t *indices = (int32_t*)keys->dk_indices; int32_t *indices = keys->dk_indices.as_4;
ix = indices[i]; ix = indices[i];
} }
#endif
else { else {
Py_ssize_t *indices = (Py_ssize_t*)keys->dk_indices; int64_t *indices = keys->dk_indices.as_8;
ix = indices[i]; ix = indices[i];
} }
assert(ix >= DKIX_DUMMY); 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); assert(ix >= DKIX_DUMMY);
if (s <= 0xff) { if (s <= 0xff) {
char *indices = (char*)keys->dk_indices; int8_t *indices = keys->dk_indices.as_1;
assert(ix <= 0x7f); assert(ix <= 0x7f);
indices[i] = (char)ix; indices[i] = (char)ix;
} }
else if (s <= 0xffff) { else if (s <= 0xffff) {
int16_t *indices = (int16_t*)keys->dk_indices; int16_t *indices = keys->dk_indices.as_2;
assert(ix <= 0x7fff); assert(ix <= 0x7fff);
indices[i] = (int16_t)ix; indices[i] = (int16_t)ix;
} }
#if SIZEOF_VOID_P > 4
else if (s <= 0xffffffff) { else if (s <= 0xffffffff) {
int32_t *indices = (int32_t*)keys->dk_indices; int32_t *indices = keys->dk_indices.as_4;
assert(ix <= 0x7fffffff); assert(ix <= 0x7fffffff);
indices[i] = (int32_t)ix; indices[i] = (int32_t)ix;
} }
#endif
else { else {
Py_ssize_t *indices = (Py_ssize_t*)keys->dk_indices; int64_t *indices = keys->dk_indices.as_8;
indices[i] = ix; indices[i] = ix;
} }
} }
@ -418,8 +414,8 @@ static PyDictKeysObject empty_keys_struct = {
lookdict_split, /* dk_lookup */ lookdict_split, /* dk_lookup */
0, /* dk_usable (immutable) */ 0, /* dk_usable (immutable) */
0, /* dk_nentries */ 0, /* dk_nentries */
{DKIX_EMPTY, DKIX_EMPTY, DKIX_EMPTY, DKIX_EMPTY, .dk_indices = { .as_1 = {DKIX_EMPTY, DKIX_EMPTY, DKIX_EMPTY, DKIX_EMPTY,
DKIX_EMPTY, DKIX_EMPTY, DKIX_EMPTY, DKIX_EMPTY}, /* dk_indices */ DKIX_EMPTY, DKIX_EMPTY, DKIX_EMPTY, DKIX_EMPTY}},
}; };
static PyObject *empty_values[1] = { NULL }; 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_usable = usable;
dk->dk_lookup = lookdict_unicode_nodummy; dk->dk_lookup = lookdict_unicode_nodummy;
dk->dk_nentries = 0; 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); memset(DK_ENTRIES(dk), 0, sizeof(PyDictKeyEntry) * usable);
return dk; return dk;
} }