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Use binary search for cp932ext*_ucs_table lookups (#12712)

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* Use binary search for cp932ext*_ucs_table lookups

A large amount of time is spent doing a linear search through these
tables in the CP932 encoding. Instead of that, we can add sorted
versions of these tables that also store the index of the non-sorted
version and perform a binary search on those sorted versions.

This reduces the time spent from 1.54s to 0.91s for the reference
benchmark [1].

[1] https://github.com/php/php-src/issues/12684#issuecomment-1813799924

* Fix search bounds
This commit is contained in:
Niels Dossche
2023-11-18 11:09:12 +00:00
committed by GitHub
parent 3ad422ebd0
commit 91279cfdc0
2 changed files with 41 additions and 20 deletions
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53
ext/mbstring/libmbfl/filters/mbfilter_cjk.c
View File

@@ -71,6 +71,23 @@ int mbfl_bisec_srch2(int w, const unsigned short tbl[], int n)
return -1;
}
static const unsigned short *mbfl_binary_search_paired_sorted_table(uint32_t w, const unsigned short tbl[][2], int n)
{
int r = n;
int l = 0;
while (l < r) {
int probe = (l + r) >> 1;
if (w < tbl[probe][0]) {
r = probe;
} else if (w > tbl[probe][0]) {
l = probe + 1;
} else {
return &tbl[probe][1];
}
}
return NULL;
}
#define SJIS_ENCODE(c1,c2,s1,s2) \
do { \
s1 = ((c1 - 1) >> 1) + ((c1) < 0x5F ? 0x71 : 0xB1); \
@@ -7639,18 +7656,16 @@ static void mb_wchar_to_cp932(uint32_t *in, size_t len, mb_convert_buf *buf, boo
}
if (!s1 || (s1 >= 0x8080 && !s2)) { /* not found or X 0212 */
for (unsigned int i = 0; i < cp932ext1_ucs_table_max - cp932ext1_ucs_table_min; i++) {
if (cp932ext1_ucs_table[i] == w) {
s1 = ((i/94 + 0x2D) << 8) + (i%94 + 0x21);
goto emit_output;
}
const unsigned short *lookup = mbfl_binary_search_paired_sorted_table(w, cp932ext1_ucs_table_paired_sorted, sizeof(cp932ext1_ucs_table_paired_sorted) / sizeof(*cp932ext1_ucs_table_paired_sorted));
if (lookup) {
s1 = ((*lookup/94 + 0x2D) << 8) + (*lookup%94 + 0x21);
goto emit_output;
}
for (unsigned int i = 0; i < cp932ext3_ucs_table_max - cp932ext3_ucs_table_min; i++) {
if (cp932ext3_ucs_table[i] == w) {
s1 = ((i/94 + 0x93) << 8) + (i%94 + 0x21);
goto emit_output;
}
lookup = mbfl_binary_search_paired_sorted_table(w, cp932ext3_ucs_table_paired_sorted, sizeof(cp932ext3_ucs_table_paired_sorted) / sizeof(*cp932ext3_ucs_table_paired_sorted));
if (lookup) {
s1 = ((*lookup/94 + 0x93) << 8) + (*lookup%94 + 0x21);
goto emit_output;
}
MB_CONVERT_ERROR(buf, out, limit, w, mb_wchar_to_cp932);
@@ -7718,18 +7733,16 @@ static void mb_wchar_to_sjiswin(uint32_t *in, size_t len, mb_convert_buf *buf, b
}
if (!s1 || (s1 >= 0x8080 && !s2)) { /* not found or X 0212 */
for (unsigned int i = 0; i < cp932ext1_ucs_table_max - cp932ext1_ucs_table_min; i++) {
if (cp932ext1_ucs_table[i] == w) {
s1 = ((i/94 + 0x2D) << 8) + (i%94 + 0x21);
goto emit_output;
}
const unsigned short *lookup = mbfl_binary_search_paired_sorted_table(w, cp932ext1_ucs_table_paired_sorted, sizeof(cp932ext1_ucs_table_paired_sorted) / sizeof(*cp932ext1_ucs_table_paired_sorted));
if (lookup) {
s1 = ((*lookup/94 + 0x2D) << 8) + (*lookup%94 + 0x21);
goto emit_output;
}
for (unsigned int i = 0; i < cp932ext3_ucs_table_max - cp932ext3_ucs_table_min; i++) {
if (cp932ext3_ucs_table[i] == w) {
s1 = ((i/94 + 0x93) << 8) + (i%94 + 0x21);
goto emit_output;
}
lookup = mbfl_binary_search_paired_sorted_table(w, cp932ext3_ucs_table_paired_sorted, sizeof(cp932ext3_ucs_table_paired_sorted) / sizeof(*cp932ext3_ucs_table_paired_sorted));
if (lookup) {
s1 = ((*lookup/94 + 0x93) << 8) + (*lookup%94 + 0x21);
goto emit_output;
}
MB_CONVERT_ERROR(buf, out, limit, w, mb_wchar_to_cp932);

8
ext/mbstring/libmbfl/filters/unicode_table_cp932_ext.h
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