pathspec: apply "*.c" optimization from exclude

When a pattern contains only a single asterisk as wildcard,
e.g. "foo*bar", after literally comparing the leading part "foo" with
the string, we can compare the tail of the string and make sure it
matches "bar", instead of running fnmatch() on "*bar" against the
remainder of the string.

-O2 build on linux-2.6, without the patch:

$ time git rev-list --quiet HEAD -- '*.c'

real    0m40.770s
user    0m40.290s
sys     0m0.256s

With the patch

$ time ~/w/git/git rev-list --quiet HEAD -- '*.c'

real    0m34.288s
user    0m33.997s
sys     0m0.205s

The above command is not supposed to be widely popular. It's chosen
because it exercises pathspec matching a lot. The point is it cuts
down matching time for popular patterns like *.c, which could be used
as pathspec in other places.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/tree-walk.c b/tree-walk.c
index 2fcf3c02da..585899ea24 100644
--- a/tree-walk.c
+++ b/tree-walk.c
@@ -628,7 +628,8 @@ enum interesting tree_entry_interesting(const struct name_entry *entry,
 
 			if (item->nowildcard_len < item->len) {
 				if (!git_fnmatch(match + baselen, entry->path,
-						 0, item->nowildcard_len - baselen))
+						 item->flags & PATHSPEC_ONESTAR ? GFNM_ONESTAR : 0,
+						 item->nowildcard_len - baselen))
 					return entry_interesting;
 
 				/*
@@ -654,7 +655,8 @@ match_wildcards:
 		strbuf_add(base, entry->path, pathlen);
 
 		if (!git_fnmatch(match, base->buf + base_offset,
-				 0, item->nowildcard_len)) {
+				 item->flags & PATHSPEC_ONESTAR ? GFNM_ONESTAR : 0,
+				 item->nowildcard_len)) {
 			strbuf_setlen(base, base_offset + baselen);
 			return entry_interesting;
 		}