[PATCH 03/11] tree-diff: don't assume compare_tree_entry() returns -1,0,1
- From
Kirill Smelkov <kirr@mns.spb.ru>
- Date
- Feb 7, 2014, 17:48 UTC
- Message-ID
- <e61a30650c98ba5a1f1a9cbc96c4ba4801cee72d.1391794688.git.kirr@mns.spb.ru>
- In-Reply-To
- <cover.1391794688.git.kirr@mns.spb.ru>
It does, but we'll be reworking it in the next patch after it won't, and besides it is better to stick to standard strcmp/memcmp/base_name_compare/etc... convention, where comparison function returns <0, =0, >0
Regarding performance, comparing for <0, =0, >0 should be a little bit faster, than switch, because it is just 1 test-without-immediate instruction and then up to 3 conditional branches, and in switch you have up to 3 tests with immediate and up to 3 conditional branches.
No worry, that update_tree_entry(t2) is duplicated for =0 and >0 - it will be good after we'll be adding support for multiparent walker and will stay that way.
=0 case goes first, because it happens more often in real diffs - i.e. paths are the same.
Signed-off-by: Kirill Smelkov <kirr@mns.spb.ru> --- tree-diff.c | 22 ++++++++++++++-------- 1 file changed, 14 insertions(+), 8 deletions(-)
diff --git a/tree-diff.c b/tree-diff.c index 0c8e3fc..c3fbfba 100644 --- a/tree-diff.c +++ b/tree-diff.c @@ -181,18 +181,24 @@ int diff_tree(struct tree_desc *t1, struct tree_desc *t2, update_tree_entry(t1); continue; } - switch (compare_tree_entry(t1, t2, &base, opt)) { - case -1: + + cmp = compare_tree_entry(t1, t2, &base, opt); + + /* t1 = t2 */ + if (cmp == 0) { update_tree_entry(t1); - continue; - case 0: + update_tree_entry(t2); + } + + /* t1 < t2 */ + else if (cmp < 0) { update_tree_entry(t1); - /* Fallthrough */ - case 1: + } + + /* t1 > t2 */ + else { update_tree_entry(t2); - continue; } - die("git diff-tree: internal error"); } strbuf_release(&base);
-- 1.9.rc1.181.g641f458