grep: don't call regexec() for fixed strings
Add the new flag "fixed" to struct grep_pat and set it if the pattern
is doesn't contain any regex control characters in addition to if the
flag -F/--fixed-strings was specified.
This gives a nice speed up on msysgit, where regexec() seems to be
extra slow. Before (best of five runs):
$ time git grep grep v1.6.1 >/dev/null
real 0m0.552s
user 0m0.000s
sys 0m0.000s
$ time git grep -F grep v1.6.1 >/dev/null
real 0m0.170s
user 0m0.000s
sys 0m0.015s
With the patch:
$ time git grep grep v1.6.1 >/dev/null
real 0m0.173s
user 0m0.000s
sys 0m0.000s
The difference is much smaller on Linux, but still measurable.
Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/grep.c b/grep.c
index 22a56b5..6485760 100644
--- a/grep.c
+++ b/grep.c
@@ -28,9 +28,31 @@
p->next = NULL;
}
+static int isregexspecial(int c)
+{
+ return isspecial(c) || c == '$' || c == '(' || c == ')' || c == '+' ||
+ c == '.' || c == '^' || c == '{' || c == '|';
+}
+
+static int is_fixed(const char *s)
+{
+ while (!isregexspecial(*s))
+ s++;
+ return !*s;
+}
+
static void compile_regexp(struct grep_pat *p, struct grep_opt *opt)
{
- int err = regcomp(&p->regexp, p->pattern, opt->regflags);
+ int err;
+
+ if (opt->fixed || is_fixed(p->pattern))
+ p->fixed = 1;
+ if (opt->regflags & REG_ICASE)
+ p->fixed = 0;
+ if (p->fixed)
+ return;
+
+ err = regcomp(&p->regexp, p->pattern, opt->regflags);
if (err) {
char errbuf[1024];
char where[1024];
@@ -159,8 +181,7 @@
case GREP_PATTERN: /* atom */
case GREP_PATTERN_HEAD:
case GREP_PATTERN_BODY:
- if (!opt->fixed)
- compile_regexp(p, opt);
+ compile_regexp(p, opt);
break;
default:
opt->extended = 1;
@@ -314,7 +335,7 @@
}
again:
- if (!opt->fixed) {
+ if (!p->fixed) {
regex_t *exp = &p->regexp;
hit = !regexec(exp, bol, ARRAY_SIZE(pmatch),
pmatch, 0);
diff --git a/grep.h b/grep.h
index 45a222d..5102ce3 100644
--- a/grep.h
+++ b/grep.h
@@ -30,6 +30,7 @@
const char *pattern;
enum grep_header_field field;
regex_t regexp;
+ unsigned fixed:1;
};
enum grep_expr_node {
