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merge-ort: avoid repeating fill_tree_descriptor() on the same tree

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Three-way merges, by their nature, are going to often have two or more
trees match at a given subdirectory.  We can avoid calling
fill_tree_descriptor() on the same tree by checking when these trees
match.  Noting when various oids match will also be useful in other
calculations and optimizations as well.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Elijah Newren 2020-12-13 08:04:14 +00:00 committed by Junio C Hamano
parent d2bc1994f3
commit 885f0063e9
1 changed files with 22 additions and 4 deletions
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26
merge-ort.c
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@ -223,6 +223,15 @@ static int collect_merge_info_callback(int n,
unsigned mbase_null = !(mask & 1); unsigned mbase_null = !(mask & 1);
unsigned side1_null = !(mask & 2); unsigned side1_null = !(mask & 2);
unsigned side2_null = !(mask & 4); unsigned side2_null = !(mask & 4);
unsigned side1_matches_mbase = (!side1_null && !mbase_null &&
names[0].mode == names[1].mode &&
oideq(&names[0].oid, &names[1].oid));
unsigned side2_matches_mbase = (!side2_null && !mbase_null &&
names[0].mode == names[2].mode &&
oideq(&names[0].oid, &names[2].oid));
unsigned sides_match = (!side1_null && !side2_null &&
names[1].mode == names[2].mode &&
oideq(&names[1].oid, &names[2].oid));
/* n = 3 is a fundamental assumption. */ /* n = 3 is a fundamental assumption. */
if (n != 3) if (n != 3)
@ -275,10 +284,19 @@ static int collect_merge_info_callback(int n,
newinfo.pathlen = st_add3(newinfo.pathlen, p->pathlen, 1); newinfo.pathlen = st_add3(newinfo.pathlen, p->pathlen, 1);
for (i = MERGE_BASE; i <= MERGE_SIDE2; i++) { for (i = MERGE_BASE; i <= MERGE_SIDE2; i++) {
const struct object_id *oid = NULL; if (i == 1 && side1_matches_mbase)
if (dirmask & 1) t[1] = t[0];
oid = &names[i].oid; else if (i == 2 && side2_matches_mbase)
buf[i] = fill_tree_descriptor(opt->repo, t + i, oid); t[2] = t[0];
else if (i == 2 && sides_match)
t[2] = t[1];
else {
const struct object_id *oid = NULL;
if (dirmask & 1)
oid = &names[i].oid;
buf[i] = fill_tree_descriptor(opt->repo,
t + i, oid);
}
dirmask >>= 1; dirmask >>= 1;
} }