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grep: short-circuit -v to bail out on first match

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A small optimization. There is no need to try matching the current
input line against any further patterns if a match was already
found and -v is specified.

function                                             old     new   delta
grep_file                                           1463    1440     -23

Signed-off-by: Ari Sundholm <ari@tuxera.com>
Signed-off-by: Niko Vähäsarja <niko@tuxera.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Ari Sundholm 2019-01-28 19:41:12 +02:00 committed by Denys Vlasenko
parent 9a9c6e39ba
commit d4b568c108
1 changed files with 14 additions and 5 deletions
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19
findutils/grep.c
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@ -443,15 +443,23 @@ static int grep_file(FILE *file)
} }
} }
} }
/* If it's non-inverted search, we can stop /* If it's a non-inverted search, we can stop
* at first match */ * at first match and report it.
if (found && !invert_search) * If it's an inverted search, we can move on
goto do_found; * to the next line of input, ignoring the
* rest of the patterns.
*/
if (found) {
//if (invert_search)
// goto do_not_found;
//goto do_found;
break; // this accomplishes both
}
pattern_ptr = pattern_ptr->link; pattern_ptr = pattern_ptr->link;
} /* while (pattern_ptr) */ } /* while (pattern_ptr) */
if (found ^ invert_search) { if (found ^ invert_search) {
do_found: //do_found:
/* keep track of matches */ /* keep track of matches */
nmatches++; nmatches++;
@ -552,6 +560,7 @@ static int grep_file(FILE *file)
} }
#if ENABLE_FEATURE_GREP_CONTEXT #if ENABLE_FEATURE_GREP_CONTEXT
else { /* no match */ else { /* no match */
//do_not_found:
/* if we need to print some context lines after the last match, do so */ /* if we need to print some context lines after the last match, do so */
if (print_n_lines_after) { if (print_n_lines_after) {
print_line(line, strlen(line), linenum, '-'); print_line(line, strlen(line), linenum, '-');