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ash: speed up ${v//pattern/repl} if !ASH_OPTIMIZE_FOR_SIZE

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function                                             old     new   delta
subevalvar                                          1353    1447     +94
.rodata                                           104179  104184      +5
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(add/remove: 0/0 grow/shrink: 2/0 up/down: 99/0)               Total: 99 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2021-07-22 18:15:59 +02:00
parent 0068ce2fa0
commit 1310d7b1d1
1 changed files with 27 additions and 3 deletions
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30
shell/ash.c
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@ -6970,7 +6970,8 @@ scanright(char *startp, char *rmesc, char *rmescend,
* Logic:
* loc starts at NUL at the end of startp, loc2 starts at the end of rmesc,
* and on each iteration they go back two/one char until they reach the beginning.
* We try to find a match in "raw_value_of_v", "raw_value_of_", "raw_value_of" etc.
* We try to match "raw_value_of_v", "raw_value_of_", "raw_value_of" etc.
* If one of these matches, return pointer past last matched char in startp.
*/
/* TODO: document in what other circumstances we are called. */
@ -7258,6 +7259,7 @@ 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;
int len;
char *idx, *end;
@ -7275,16 +7277,38 @@ 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);
len = 0;
idx = startp;
end = str - 1;
while (idx <= end) {
try_to_match:
loc = scanright(idx, rmesc, rmescend, str, quotes, 1);
if (no_meta_len == 0) {
/* pattern has meta chars, have to glob; or ENABLE_ASH_OPTIMIZE_FOR_SIZE */
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//:/|}"
*/
size_t n;
if (strncmp(rmesc, str, no_meta_len) != 0)
goto no_match;
n = no_meta_len;
loc = idx;
do {
if (quotes && (unsigned char)*loc == CTLESC)
loc++;
loc++;
} while (--n != 0);
}
//bb_error_msg("scanright('%s'):'%s'", str, loc);
if (!loc) {
char *restart_detect;
no_match:
/* No match, advance */
char *restart_detect = stackblock();
restart_detect = stackblock();
skip_matching:
if (idx >= end)
break;