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Sixteen bit hash for strings #1170

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Merged
merged 1 commit into from
Jun 28, 2016
Merged

Sixteen bit hash for strings #1170

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1 change: 0 additions & 1 deletion jerry-core/ecma/base/ecma-helpers-string.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1286,7 +1286,6 @@ ecma_is_string_magic (const ecma_string_t *string_p, /**< ecma-string */
*/
lit_string_hash_t
ecma_string_hash (const ecma_string_t *string_p) /**< ecma-string to calculate hash for */

{
return (string_p->hash);
} /* ecma_string_hash */
Expand Down
12 changes: 6 additions & 6 deletions jerry-core/ecma/base/ecma-property-hashmap.c
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Expand Up @@ -124,13 +124,13 @@ ecma_property_hashmap_create (ecma_object_t *object_p) /**< object */

uint8_t shift_counter = 0;

if (max_property_count <= (1u << LIT_STRING_HASH_BITS))
if (max_property_count <= LIT_STRING_HASH_LIMIT)
{
hashmap_p->header.types[1].type_and_flags = 0;
}
else
{
while (max_property_count > (1u << LIT_STRING_HASH_BITS))
while (max_property_count > LIT_STRING_HASH_LIMIT)
{
shift_counter++;
max_property_count >>= 1;
Expand Down Expand Up @@ -162,7 +162,7 @@ ecma_property_hashmap_create (ecma_object_t *object_p) /**< object */
uint32_t entry_index = name_p->hash;
uint32_t step = ecma_property_hashmap_steps[entry_index & (ECMA_PROPERTY_HASHMAP_NUMBER_OF_STEPS - 1)];

if (mask < (1u << LIT_STRING_HASH_BITS))
if (mask < LIT_STRING_HASH_LIMIT)
{
entry_index &= mask;
}
Expand Down Expand Up @@ -261,7 +261,7 @@ ecma_property_hashmap_insert (ecma_object_t *object_p, /**< object */
uint32_t step = ecma_property_hashmap_steps[entry_index & (ECMA_PROPERTY_HASHMAP_NUMBER_OF_STEPS - 1)];
uint32_t mask = hashmap_p->max_property_count - 1;

if (mask < (1u << LIT_STRING_HASH_BITS))
if (mask < LIT_STRING_HASH_LIMIT)
{
entry_index &= mask;
}
Expand Down Expand Up @@ -336,7 +336,7 @@ ecma_property_hashmap_delete (ecma_object_t *object_p, /**< object */
jmem_cpointer_t *pair_list_p = (jmem_cpointer_t *) (hashmap_p + 1);
uint8_t *bits_p = (uint8_t *) (pair_list_p + hashmap_p->max_property_count);

if (mask < (1u << LIT_STRING_HASH_BITS))
if (mask < LIT_STRING_HASH_LIMIT)
{
entry_index &= mask;
}
Expand Down Expand Up @@ -446,7 +446,7 @@ ecma_property_hashmap_find (ecma_property_hashmap_t *hashmap_p, /**< hashmap */
jmem_cpointer_t *pair_list_p = (jmem_cpointer_t *) (hashmap_p + 1);
uint8_t *bits_p = (uint8_t *) (pair_list_p + hashmap_p->max_property_count);

if (mask < (1u << LIT_STRING_HASH_BITS))
if (mask < LIT_STRING_HASH_LIMIT)
{
entry_index &= mask;
}
Expand Down
20 changes: 13 additions & 7 deletions jerry-core/ecma/operations/ecma-objects.c
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Original file line number Diff line number Diff line change
Expand Up @@ -31,6 +31,11 @@
* @{
*/

/**
* Hash bitmap size for ecma objects
*/
#define ECMA_OBJECT_HASH_BITMAP_SIZE 256

/**
* Assert that specified object type value is valid
*
Expand All @@ -48,6 +53,7 @@
#else /* JERRY_NDEBUG */
#define JERRY_ASSERT_OBJECT_TYPE_IS_VALID(type)
#endif /* !JERRY_NDEBUG */

/**
* [[Get]] ecma object's operation
*
Expand Down Expand Up @@ -483,7 +489,7 @@ ecma_op_object_is_prototype_of (ecma_object_t *base_p, /**< base object */
*
* Order of names in the collection:
* - integer indices in ascending order
* - other indices in creation order (for built-ins - in the order the properties are listed in specification).
* - other indices in creation order (for built-ins: the order of the properties are listed in specification).
*
* Note:
* Implementation of the routine assumes that new properties are appended to beginning of corresponding object's
Expand All @@ -510,7 +516,7 @@ ecma_op_object_get_property_names (ecma_object_t *obj_p, /**< object */
const bool obj_is_builtin = ecma_get_object_is_builtin (obj_p);

const size_t bitmap_row_size = sizeof (uint32_t) * JERRY_BITSINBYTE;
uint32_t names_hashes_bitmap[(1u << LIT_STRING_HASH_BITS) / bitmap_row_size];
uint32_t names_hashes_bitmap[ECMA_OBJECT_HASH_BITMAP_SIZE / bitmap_row_size];

memset (names_hashes_bitmap, 0, sizeof (names_hashes_bitmap));

Expand Down Expand Up @@ -571,14 +577,14 @@ ecma_op_object_get_property_names (ecma_object_t *obj_p, /**< object */
ecma_collection_iterator_t iter;
ecma_collection_iterator_init (&iter, prop_names_p);

uint32_t own_names_hashes_bitmap[(1u << LIT_STRING_HASH_BITS) / bitmap_row_size];
uint32_t own_names_hashes_bitmap[ECMA_OBJECT_HASH_BITMAP_SIZE / bitmap_row_size];
memset (own_names_hashes_bitmap, 0, sizeof (own_names_hashes_bitmap));

while (ecma_collection_iterator_next (&iter))
{
ecma_string_t *name_p = ecma_get_string_from_value (*iter.current_value_p);

lit_string_hash_t hash = name_p->hash;
uint8_t hash = (uint8_t) name_p->hash;
uint32_t bitmap_row = (uint32_t) (hash / bitmap_row_size);
uint32_t bitmap_column = (uint32_t) (hash % bitmap_row_size);

Expand Down Expand Up @@ -613,7 +619,7 @@ ecma_op_object_get_property_names (ecma_object_t *obj_p, /**< object */

if (!(is_enumerable_only && !ecma_is_property_enumerable (property_p)))
{
lit_string_hash_t hash = name_p->hash;
uint8_t hash = (uint8_t) name_p->hash;
uint32_t bitmap_row = (uint32_t) (hash / bitmap_row_size);
uint32_t bitmap_column = (uint32_t) (hash % bitmap_row_size);

Expand Down Expand Up @@ -652,7 +658,7 @@ ecma_op_object_get_property_names (ecma_object_t *obj_p, /**< object */
ecma_make_string_value (name_p),
true);

lit_string_hash_t hash = name_p->hash;
uint8_t hash = (uint8_t) name_p->hash;
uint32_t bitmap_row = (uint32_t) (hash / bitmap_row_size);
uint32_t bitmap_column = (uint32_t) (hash % bitmap_row_size);

Expand Down Expand Up @@ -771,7 +777,7 @@ ecma_op_object_get_property_names (ecma_object_t *obj_p, /**< object */

ecma_string_t *name_p = names_p[i];

lit_string_hash_t hash = name_p->hash;
uint8_t hash = (uint8_t) name_p->hash;
uint32_t bitmap_row = (uint32_t) (hash / bitmap_row_size);
uint32_t bitmap_column = (uint32_t) (hash % bitmap_row_size);

Expand Down
11 changes: 8 additions & 3 deletions jerry-core/lit/lit-globals.h
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Expand Up @@ -126,11 +126,16 @@ typedef uint32_t lit_code_point_t;
/**
* ECMA string hash
*/
typedef uint8_t lit_string_hash_t;
typedef uint16_t lit_string_hash_t;

/**
* ECMA string hash value length, in bits
* Maximum value of ECMA string hash + 1
*
* Note:
* On ARM, this constant can be encoded as an immediate value
* while 0xffffu cannot be. Hence using this constant reduces
* binary size and improves performance.
*/
#define LIT_STRING_HASH_BITS (sizeof (lit_string_hash_t) * JERRY_BITSINBYTE)
#define LIT_STRING_HASH_LIMIT 0x10000u

#endif /* !LIT_GLOBALS_H */