Skip to content

Commit 981346f

Browse files
borsbors
committed
Auto merge of #78151 - tmiasko:disable-match-branch-simplification, r=wesleywiser
Disable MatchBranchSimplification This optimization can result in unsoundness, because it introduces additional uses of a place holding the discriminant value without ensuring that it is valid to do so. Found by validation from #77369 / #78147.
2 parents 9832374 + c2af254 commit 981346f

7 files changed

+179
-150
lines changed

‎compiler/rustc_mir/src/transform/match_branches.rs

+7
Original file line numberDiff line numberDiff line change
@@ -38,6 +38,13 @@ pub struct MatchBranchSimplification;
3838
3939
impl<'tcx> MirPass<'tcx> for MatchBranchSimplification {
4040
fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
41+
// FIXME: This optimization can result in unsoundness, because it introduces
42+
// additional uses of a place holding the discriminant value without ensuring that
43+
// it is valid to do so.
44+
if !tcx.sess.opts.debugging_opts.unsound_mir_opts {
45+
return;
46+
}
47+
4148
let param_env = tcx.param_env(body.source.def_id());
4249
let bbs = body.basic_blocks_mut();
4350
'outer: for bb_idx in bbs.indices() {

‎src/test/mir-opt/matches_reduce_branches.bar.MatchBranchSimplification.32bit.diff

+58-58
Original file line numberDiff line numberDiff line change
@@ -2,83 +2,83 @@
22
+ // MIR for `bar` after MatchBranchSimplification
33

44
fn bar(_1: i32) -> (bool, bool, bool, bool) {
5-
debug i => _1; // in scope 0 at $DIR/matches_reduce_branches.rs:11:8: 11:9
6-
let mut _0: (bool, bool, bool, bool); // return place in scope 0 at $DIR/matches_reduce_branches.rs:11:19: 11:43
7-
let _2: bool; // in scope 0 at $DIR/matches_reduce_branches.rs:12:9: 12:10
8-
let _6: (); // in scope 0 at $DIR/matches_reduce_branches.rs:17:5: 32:6
9-
let mut _7: bool; // in scope 0 at $DIR/matches_reduce_branches.rs:34:6: 34:7
10-
let mut _8: bool; // in scope 0 at $DIR/matches_reduce_branches.rs:34:9: 34:10
11-
let mut _9: bool; // in scope 0 at $DIR/matches_reduce_branches.rs:34:12: 34:13
12-
let mut _10: bool; // in scope 0 at $DIR/matches_reduce_branches.rs:34:15: 34:16
5+
debug i => _1; // in scope 0 at $DIR/matches_reduce_branches.rs:12:8: 12:9
6+
let mut _0: (bool, bool, bool, bool); // return place in scope 0 at $DIR/matches_reduce_branches.rs:12:19: 12:43
7+
let _2: bool; // in scope 0 at $DIR/matches_reduce_branches.rs:13:9: 13:10
8+
let _6: (); // in scope 0 at $DIR/matches_reduce_branches.rs:18:5: 33:6
9+
let mut _7: bool; // in scope 0 at $DIR/matches_reduce_branches.rs:35:6: 35:7
10+
let mut _8: bool; // in scope 0 at $DIR/matches_reduce_branches.rs:35:9: 35:10
11+
let mut _9: bool; // in scope 0 at $DIR/matches_reduce_branches.rs:35:12: 35:13
12+
let mut _10: bool; // in scope 0 at $DIR/matches_reduce_branches.rs:35:15: 35:16
1313
scope 1 {
14-
debug a => _2; // in scope 1 at $DIR/matches_reduce_branches.rs:12:9: 12:10
15-
let _3: bool; // in scope 1 at $DIR/matches_reduce_branches.rs:13:9: 13:10
14+
debug a => _2; // in scope 1 at $DIR/matches_reduce_branches.rs:13:9: 13:10
15+
let _3: bool; // in scope 1 at $DIR/matches_reduce_branches.rs:14:9: 14:10
1616
scope 2 {
17-
debug b => _3; // in scope 2 at $DIR/matches_reduce_branches.rs:13:9: 13:10
18-
let _4: bool; // in scope 2 at $DIR/matches_reduce_branches.rs:14:9: 14:10
17+
debug b => _3; // in scope 2 at $DIR/matches_reduce_branches.rs:14:9: 14:10
18+
let _4: bool; // in scope 2 at $DIR/matches_reduce_branches.rs:15:9: 15:10
1919
scope 3 {
20-
debug c => _4; // in scope 3 at $DIR/matches_reduce_branches.rs:14:9: 14:10
21-
let _5: bool; // in scope 3 at $DIR/matches_reduce_branches.rs:15:9: 15:10
20+
debug c => _4; // in scope 3 at $DIR/matches_reduce_branches.rs:15:9: 15:10
21+
let _5: bool; // in scope 3 at $DIR/matches_reduce_branches.rs:16:9: 16:10
2222
scope 4 {
23-
debug d => _5; // in scope 4 at $DIR/matches_reduce_branches.rs:15:9: 15:10
23+
debug d => _5; // in scope 4 at $DIR/matches_reduce_branches.rs:16:9: 16:10
2424
}
2525
}
2626
}
2727
}
2828

2929
bb0: {
30-
StorageLive(_2); // scope 0 at $DIR/matches_reduce_branches.rs:12:9: 12:10
31-
StorageLive(_3); // scope 1 at $DIR/matches_reduce_branches.rs:13:9: 13:10
32-
StorageLive(_4); // scope 2 at $DIR/matches_reduce_branches.rs:14:9: 14:10
33-
StorageLive(_5); // scope 3 at $DIR/matches_reduce_branches.rs:15:9: 15:10
34-
StorageLive(_6); // scope 4 at $DIR/matches_reduce_branches.rs:17:5: 32:6
35-
- switchInt(_1) -> [7_i32: bb2, otherwise: bb1]; // scope 4 at $DIR/matches_reduce_branches.rs:18:9: 18:10
36-
+ _2 = Ne(_1, const 7_i32); // scope 4 at $DIR/matches_reduce_branches.rs:19:13: 19:22
37-
+ _3 = Eq(_1, const 7_i32); // scope 4 at $DIR/matches_reduce_branches.rs:20:13: 20:21
38-
+ _4 = const false; // scope 4 at $DIR/matches_reduce_branches.rs:21:13: 21:22
39-
+ _5 = const true; // scope 4 at $DIR/matches_reduce_branches.rs:22:13: 22:21
40-
+ goto -> bb3; // scope 4 at $DIR/matches_reduce_branches.rs:18:9: 18:10
30+
StorageLive(_2); // scope 0 at $DIR/matches_reduce_branches.rs:13:9: 13:10
31+
StorageLive(_3); // scope 1 at $DIR/matches_reduce_branches.rs:14:9: 14:10
32+
StorageLive(_4); // scope 2 at $DIR/matches_reduce_branches.rs:15:9: 15:10
33+
StorageLive(_5); // scope 3 at $DIR/matches_reduce_branches.rs:16:9: 16:10
34+
StorageLive(_6); // scope 4 at $DIR/matches_reduce_branches.rs:18:5: 33:6
35+
- switchInt(_1) -> [7_i32: bb2, otherwise: bb1]; // scope 4 at $DIR/matches_reduce_branches.rs:19:9: 19:10
36+
+ _2 = Ne(_1, const 7_i32); // scope 4 at $DIR/matches_reduce_branches.rs:20:13: 20:22
37+
+ _3 = Eq(_1, const 7_i32); // scope 4 at $DIR/matches_reduce_branches.rs:21:13: 21:21
38+
+ _4 = const false; // scope 4 at $DIR/matches_reduce_branches.rs:22:13: 22:22
39+
+ _5 = const true; // scope 4 at $DIR/matches_reduce_branches.rs:23:13: 23:21
40+
+ goto -> bb3; // scope 4 at $DIR/matches_reduce_branches.rs:19:9: 19:10
4141
}
4242

4343
bb1: {
44-
_2 = const true; // scope 4 at $DIR/matches_reduce_branches.rs:26:13: 26:21
45-
_3 = const false; // scope 4 at $DIR/matches_reduce_branches.rs:27:13: 27:22
46-
_4 = const false; // scope 4 at $DIR/matches_reduce_branches.rs:28:13: 28:22
47-
_5 = const true; // scope 4 at $DIR/matches_reduce_branches.rs:29:13: 29:21
48-
goto -> bb3; // scope 4 at $DIR/matches_reduce_branches.rs:17:5: 32:6
44+
_2 = const true; // scope 4 at $DIR/matches_reduce_branches.rs:27:13: 27:21
45+
_3 = const false; // scope 4 at $DIR/matches_reduce_branches.rs:28:13: 28:22
46+
_4 = const false; // scope 4 at $DIR/matches_reduce_branches.rs:29:13: 29:22
47+
_5 = const true; // scope 4 at $DIR/matches_reduce_branches.rs:30:13: 30:21
48+
goto -> bb3; // scope 4 at $DIR/matches_reduce_branches.rs:18:5: 33:6
4949
}
5050

5151
bb2: {
52-
_2 = const false; // scope 4 at $DIR/matches_reduce_branches.rs:19:13: 19:22
53-
_3 = const true; // scope 4 at $DIR/matches_reduce_branches.rs:20:13: 20:21
54-
_4 = const false; // scope 4 at $DIR/matches_reduce_branches.rs:21:13: 21:22
55-
_5 = const true; // scope 4 at $DIR/matches_reduce_branches.rs:22:13: 22:21
56-
goto -> bb3; // scope 4 at $DIR/matches_reduce_branches.rs:17:5: 32:6
52+
_2 = const false; // scope 4 at $DIR/matches_reduce_branches.rs:20:13: 20:22
53+
_3 = const true; // scope 4 at $DIR/matches_reduce_branches.rs:21:13: 21:21
54+
_4 = const false; // scope 4 at $DIR/matches_reduce_branches.rs:22:13: 22:22
55+
_5 = const true; // scope 4 at $DIR/matches_reduce_branches.rs:23:13: 23:21
56+
goto -> bb3; // scope 4 at $DIR/matches_reduce_branches.rs:18:5: 33:6
5757
}
5858

5959
bb3: {
60-
StorageDead(_6); // scope 4 at $DIR/matches_reduce_branches.rs:32:6: 32:7
61-
StorageLive(_7); // scope 4 at $DIR/matches_reduce_branches.rs:34:6: 34:7
62-
_7 = _2; // scope 4 at $DIR/matches_reduce_branches.rs:34:6: 34:7
63-
StorageLive(_8); // scope 4 at $DIR/matches_reduce_branches.rs:34:9: 34:10
64-
_8 = _3; // scope 4 at $DIR/matches_reduce_branches.rs:34:9: 34:10
65-
StorageLive(_9); // scope 4 at $DIR/matches_reduce_branches.rs:34:12: 34:13
66-
_9 = _4; // scope 4 at $DIR/matches_reduce_branches.rs:34:12: 34:13
67-
StorageLive(_10); // scope 4 at $DIR/matches_reduce_branches.rs:34:15: 34:16
68-
_10 = _5; // scope 4 at $DIR/matches_reduce_branches.rs:34:15: 34:16
69-
(_0.0: bool) = move _7; // scope 4 at $DIR/matches_reduce_branches.rs:34:5: 34:17
70-
(_0.1: bool) = move _8; // scope 4 at $DIR/matches_reduce_branches.rs:34:5: 34:17
71-
(_0.2: bool) = move _9; // scope 4 at $DIR/matches_reduce_branches.rs:34:5: 34:17
72-
(_0.3: bool) = move _10; // scope 4 at $DIR/matches_reduce_branches.rs:34:5: 34:17
73-
StorageDead(_10); // scope 4 at $DIR/matches_reduce_branches.rs:34:16: 34:17
74-
StorageDead(_9); // scope 4 at $DIR/matches_reduce_branches.rs:34:16: 34:17
75-
StorageDead(_8); // scope 4 at $DIR/matches_reduce_branches.rs:34:16: 34:17
76-
StorageDead(_7); // scope 4 at $DIR/matches_reduce_branches.rs:34:16: 34:17
77-
StorageDead(_5); // scope 3 at $DIR/matches_reduce_branches.rs:35:1: 35:2
78-
StorageDead(_4); // scope 2 at $DIR/matches_reduce_branches.rs:35:1: 35:2
79-
StorageDead(_3); // scope 1 at $DIR/matches_reduce_branches.rs:35:1: 35:2
80-
StorageDead(_2); // scope 0 at $DIR/matches_reduce_branches.rs:35:1: 35:2
81-
return; // scope 0 at $DIR/matches_reduce_branches.rs:35:2: 35:2
60+
StorageDead(_6); // scope 4 at $DIR/matches_reduce_branches.rs:33:6: 33:7
61+
StorageLive(_7); // scope 4 at $DIR/matches_reduce_branches.rs:35:6: 35:7
62+
_7 = _2; // scope 4 at $DIR/matches_reduce_branches.rs:35:6: 35:7
63+
StorageLive(_8); // scope 4 at $DIR/matches_reduce_branches.rs:35:9: 35:10
64+
_8 = _3; // scope 4 at $DIR/matches_reduce_branches.rs:35:9: 35:10
65+
StorageLive(_9); // scope 4 at $DIR/matches_reduce_branches.rs:35:12: 35:13
66+
_9 = _4; // scope 4 at $DIR/matches_reduce_branches.rs:35:12: 35:13
67+
StorageLive(_10); // scope 4 at $DIR/matches_reduce_branches.rs:35:15: 35:16
68+
_10 = _5; // scope 4 at $DIR/matches_reduce_branches.rs:35:15: 35:16
69+
(_0.0: bool) = move _7; // scope 4 at $DIR/matches_reduce_branches.rs:35:5: 35:17
70+
(_0.1: bool) = move _8; // scope 4 at $DIR/matches_reduce_branches.rs:35:5: 35:17
71+
(_0.2: bool) = move _9; // scope 4 at $DIR/matches_reduce_branches.rs:35:5: 35:17
72+
(_0.3: bool) = move _10; // scope 4 at $DIR/matches_reduce_branches.rs:35:5: 35:17
73+
StorageDead(_10); // scope 4 at $DIR/matches_reduce_branches.rs:35:16: 35:17
74+
StorageDead(_9); // scope 4 at $DIR/matches_reduce_branches.rs:35:16: 35:17
75+
StorageDead(_8); // scope 4 at $DIR/matches_reduce_branches.rs:35:16: 35:17
76+
StorageDead(_7); // scope 4 at $DIR/matches_reduce_branches.rs:35:16: 35:17
77+
StorageDead(_5); // scope 3 at $DIR/matches_reduce_branches.rs:36:1: 36:2
78+
StorageDead(_4); // scope 2 at $DIR/matches_reduce_branches.rs:36:1: 36:2
79+
StorageDead(_3); // scope 1 at $DIR/matches_reduce_branches.rs:36:1: 36:2
80+
StorageDead(_2); // scope 0 at $DIR/matches_reduce_branches.rs:36:1: 36:2
81+
return; // scope 0 at $DIR/matches_reduce_branches.rs:36:2: 36:2
8282
}
8383
}
8484

0 commit comments

Comments
 (0)