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Optimize uint32 hash computation. #1107

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Merged
merged 1 commit into from
Jun 1, 2016
Merged

Optimize uint32 hash computation. #1107

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2 changes: 1 addition & 1 deletion jerry-core/ecma/base/ecma-globals.h
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Original file line number Diff line number Diff line change
Expand Up @@ -734,7 +734,7 @@ typedef double ecma_number_t;
/**
* Maximum number of characters in string representation of ecma-uint32
*/
#define ECMA_MAX_CHARS_IN_STRINGIFIED_UINT32 32
#define ECMA_MAX_CHARS_IN_STRINGIFIED_UINT32 10

/**
* Maximum value of valid array index
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20 changes: 8 additions & 12 deletions jerry-core/ecma/base/ecma-helpers-conversion.c
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Expand Up @@ -783,29 +783,25 @@ ecma_uint32_to_utf8_string (uint32_t value, /**< value to convert */
lit_utf8_byte_t *out_buffer_p, /**< buffer for string */
lit_utf8_size_t buffer_size) /**< size of buffer */
{
const lit_utf8_byte_t digits[10] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9' };

lit_utf8_byte_t *p = out_buffer_p + buffer_size - 1;
lit_utf8_size_t bytes_copied = 0;
lit_utf8_byte_t *buf_p = out_buffer_p + buffer_size;

do
{
JERRY_ASSERT (p >= out_buffer_p);
JERRY_ASSERT (buf_p >= out_buffer_p);

*p-- = digits[value % 10];
buf_p--;
*buf_p = (lit_utf8_byte_t) ((value % 10) + LIT_CHAR_0);
value /= 10;

bytes_copied++;
}
while (value != 0);

p++;
JERRY_ASSERT (buf_p >= out_buffer_p);

JERRY_ASSERT (p >= out_buffer_p);
lit_utf8_size_t bytes_copied = (lit_utf8_size_t) (out_buffer_p + buffer_size - buf_p);

if (likely (p != out_buffer_p))
if (likely (buf_p != out_buffer_p))
{
memmove (out_buffer_p, p, bytes_copied);
memmove (out_buffer_p, buf_p, bytes_copied);
}

return bytes_copied;
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24 changes: 17 additions & 7 deletions jerry-core/ecma/base/ecma-helpers-string.c
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Expand Up @@ -229,15 +229,25 @@ ecma_new_ecma_string_from_code_unit (ecma_char_t code_unit) /**< code unit */
ecma_string_t *
ecma_new_ecma_string_from_uint32 (uint32_t uint32_number) /**< UInt32-represented ecma-number */
{
ecma_string_t *string_desc_p = ecma_alloc_string ();
string_desc_p->refs_and_container = ECMA_STRING_CONTAINER_UINT32_IN_DESC | ECMA_STRING_REF_ONE;

lit_utf8_byte_t byte_buf[ECMA_MAX_CHARS_IN_STRINGIFIED_UINT32];
lit_utf8_size_t bytes_copied = ecma_uint32_to_utf8_string (uint32_number,
byte_buf,
ECMA_MAX_CHARS_IN_STRINGIFIED_UINT32);
lit_utf8_byte_t *buf_p = byte_buf + ECMA_MAX_CHARS_IN_STRINGIFIED_UINT32;

uint32_t value = uint32_number;
do
{
JERRY_ASSERT (buf_p >= byte_buf);

string_desc_p->hash = lit_utf8_string_calc_hash (byte_buf, bytes_copied);
buf_p--;
*buf_p = (lit_utf8_byte_t) ((value % 10) + LIT_CHAR_0);
value /= 10;
}
while (value != 0);
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This loop is the same as used in ecma_uint32_to_utf8_string. Wouldn't be better if we made that function always inline?

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No, because that function is called from several places, and only this one is time critical. The memmove part is also not needed here.

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Only a few. You eliminated one, so 2 call remains after this PR.


lit_utf8_size_t size = (lit_utf8_size_t) (byte_buf + ECMA_MAX_CHARS_IN_STRINGIFIED_UINT32 - buf_p);

ecma_string_t *string_desc_p = ecma_alloc_string ();
string_desc_p->refs_and_container = ECMA_STRING_CONTAINER_UINT32_IN_DESC | ECMA_STRING_REF_ONE;
string_desc_p->hash = lit_utf8_string_calc_hash (buf_p, size);

string_desc_p->u.common_field = 0;
string_desc_p->u.uint32_number = uint32_number;
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