revision.c: discount side branches when computing TREESAME

Use the BOTTOM flag to define relevance for pruning. Relevant commits
are those that are !UNINTERESTING or BOTTOM, and this allows us to
identify irrelevant side branches (UNINTERESTING && !BOTTOM).

If a merge has relevant parents, and it is TREESAME to them, then do not
let irrelevant parents cause the merge to be treated as !TREESAME.

When considering simplification, don't always include all merges -
merges with exactly one relevant parent can be simplified, if TREESAME
according to the above rule.

These two changes greatly increase simplification in limited, pruned
revision lists.

Signed-off-by: Kevin Bracey <kevin@bracey.fi>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

2 files changed, 14 insertions, 6 deletions

diff --git a/t/t6019-rev-list-ancestry-path.sh b/t/t6019-rev-list-ancestry-path.sh
index 5ad96e3..dabebae 100755
--- a/t/t6019-rev-list-ancestry-path.sh
+++ b/t/t6019-rev-list-ancestry-path.sh
@@ -18,7 +18,8 @@ test_description='--ancestry-path'
 #  --ancestry-path F...I == F H I
 #
 #  G..M -- G.t                 == [nothing - was dropped in "-s ours" merge L]
-#  --ancestry-path G..M -- G.t == H J L
+#  --ancestry-path G..M -- G.t == L
+#  --ancestry-path --simplify-merges G^..M -- G.t == G L
 
 . ./test-lib.sh
 
@@ -101,8 +102,15 @@ test_expect_success 'rev-list G..M -- G.t' '
 '
 
 test_expect_success 'rev-list --ancestry-path G..M -- G.t' '
-	for c in H J L; do echo $c; done >expect &&
+	echo L >expect &&
 	git rev-list --ancestry-path --format=%s G..M -- G.t |
+	sed -e "/^commit /d" >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'rev-list --ancestry-path --simplify-merges G^..M -- G.t' '
+	for c in G L; do echo $c; done >expect &&
+	git rev-list --ancestry-path --simplify-merges --format=%s G^..M -- G.t |
 	sed -e "/^commit /d" |
 	sort >actual &&
 	test_cmp expect actual
diff --git a/t/t6111-rev-list-treesame.sh b/t/t6111-rev-list-treesame.sh
index 484b69b..e32b373 100755
--- a/t/t6111-rev-list-treesame.sh
+++ b/t/t6111-rev-list-treesame.sh
@@ -138,9 +138,9 @@ check_result 'M L G' F..M --first-parent -- file
 # Note that G is pruned when E is the bottom, even if it's the same commit list
 # If we want history since E, then we're quite happy to ignore G that took E.
 check_result 'M L K J I H G' E..M --ancestry-path
-check_outcome failure 'M L J I H' E..M --ancestry-path -- file # includes G
+check_result 'M L J I H' E..M --ancestry-path -- file
 check_outcome failure '(LH)M (K)L (EJ)K (I)J (E)I (E)H' E..M --ancestry-path --parents -- file # includes G
-check_outcome failure '(LH)M (E)H (J)L (I)J (E)I' E..M --ancestry-path --simplify-merges -- file # includes G
+check_result '(LH)M (E)H (J)L (I)J (E)I' E..M --ancestry-path --simplify-merges -- file
 
 # Should still be able to ignore I-J branch in simple log, despite limiting
 # to G.
@@ -167,9 +167,9 @@ check_result 'F D' B..F --full-history -- file
 check_result '(D)F (BA)D' B..F --full-history --parents -- file
 check_result '(B)F' B..F --simplify-merges -- file
 check_result 'F D' B..F --ancestry-path
-check_outcome failure 'F' B..F --ancestry-path -- file # includes D
+check_result 'F' B..F --ancestry-path -- file
 check_outcome failure 'F' B..F --ancestry-path --parents -- file # includes D
-check_outcome failure 'F' B..F --ancestry-path --simplify-merges -- file # includes D
+check_result 'F' B..F --ancestry-path --simplify-merges -- file
 check_result 'F D' B..F --first-parent
 check_result 'F' B..F --first-parent -- file