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ash: speed up ${x//\*/|} too, make it independent of ASH_OPTIMIZE_FOR_SIZE

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function                                             old     new   delta
subevalvar                                          1503    1545     +42

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2021-10-09 03:32:20 +02:00
parent 21e8dbfd9d
commit 5aaeb550b7
1 changed files with 12 additions and 6 deletions
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18
shell/ash.c
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@ -7251,7 +7251,7 @@ subevalvar(char *start, char *str, int strloc,
#if BASH_PATTERN_SUBST
workloc = expdest - (char *)stackblock();
if (subtype == VSREPLACE || subtype == VSREPLACEALL) {
size_t no_meta_len;
size_t no_meta_len, first_escaped;
int len;
char *idx, *end;
@ -7269,28 +7269,34 @@ subevalvar(char *start, char *str, int strloc,
if (str[0] == '\0')
goto out1;
no_meta_len = (ENABLE_ASH_OPTIMIZE_FOR_SIZE || strpbrk(str, "*?[\\")) ? 0 : strlen(str);
first_escaped = (str[0] == '\\' && str[1]);
/* "first_escaped" trick allows to treat e.g. "\*no_glob_chars"
* as literal too (as it is semi-common, and easy to accomodate
* by just using str + 1).
*/
no_meta_len = strpbrk(str + first_escaped * 2, "*?[\\") ? 0 : strlen(str);
len = 0;
idx = startp;
end = str - 1;
while (idx <= end) {
try_to_match:
if (no_meta_len == 0) {
/* pattern has meta chars, have to glob; or ENABLE_ASH_OPTIMIZE_FOR_SIZE */
/* pattern has meta chars, have to glob */
loc = scanright(idx, rmesc, rmescend, str, quotes, /*match_at_start:*/ 1);
} else {
/* Testcase for very slow replace (performs about 22k replaces):
* x=::::::::::::::::::::::
* x=$x$x;x=$x$x;x=$x$x;x=$x$x;x=$x$x;x=$x$x;x=$x$x;x=$x$x;x=$x$x;x=$x$x;echo ${#x}
* echo "${x//:/|}"
* To test "first_escaped" logic, replace : with *.
*/
if (strncmp(rmesc, str, no_meta_len) != 0)
if (strncmp(rmesc, str + first_escaped, no_meta_len - first_escaped) != 0)
goto no_match;
loc = idx;
if (!quotes) {
loc += no_meta_len;
loc += no_meta_len - first_escaped;
} else {
size_t n = no_meta_len;
size_t n = no_meta_len - first_escaped;
do {
if ((unsigned char)*loc == CTLESC)
loc++;