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matthiaskrgrmatthiaskrgr
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Rollup merge of rust-lang#107524 - cjgillot:both-storage, r=RalfJung
Remove both StorageLive and StorageDead in CopyProp. Fixes rust-lang#107511 rust-lang#106908 removed StorageDead without the accompanying StorageLive. In loops, execution would see repeated StorageLive, without any StorageDead, which is UB. So when removing storage statements, we have to remove both StorageLive and StorageDead. ~I also added a MIR validation pass for StorageLive. It may be a bit overzealous.~
2 parents 230c9e9 + e8ac040 commit 6917040

20 files changed

+176
-48
lines changed

‎compiler/rustc_mir_transform/src/copy_prop.rs‎

Lines changed: 14 additions & 11 deletions
Original file line numberDiff line numberDiff line change
@@ -162,17 +162,20 @@ impl<'tcx> MutVisitor<'tcx> for Replacer<'_, 'tcx> {
162162
}
163163

164164
fn visit_statement(&mut self, stmt: &mut Statement<'tcx>, loc: Location) {
165-
if let StatementKind::StorageDead(l) = stmt.kind
166-
&& self.storage_to_remove.contains(l)
167-
{
168-
stmt.make_nop();
169-
} else if let StatementKind::Assign(box (ref place, ref mut rvalue)) = stmt.kind
170-
&& place.as_local().is_some()
171-
{
172-
// Do not replace assignments.
173-
self.visit_rvalue(rvalue, loc)
174-
} else {
175-
self.super_statement(stmt, loc);
165+
match stmt.kind {
166+
// When removing storage statements, we need to remove both (#107511).
167+
StatementKind::StorageLive(l) | StatementKind::StorageDead(l)
168+
if self.storage_to_remove.contains(l) =>
169+
{
170+
stmt.make_nop()
171+
}
172+
StatementKind::Assign(box (ref place, ref mut rvalue))
173+
if place.as_local().is_some() =>
174+
{
175+
// Do not replace assignments.
176+
self.visit_rvalue(rvalue, loc)
177+
}
178+
_ => self.super_statement(stmt, loc),
176179
}
177180
}
178181
}

‎tests/mir-opt/const_debuginfo.main.ConstDebugInfo.diff‎

Lines changed: 0 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -56,11 +56,8 @@
5656
}
5757

5858
bb0: {
59-
StorageLive(_1); // scope 0 at $DIR/const_debuginfo.rs:+1:9: +1:10
6059
_1 = const 1_u8; // scope 0 at $DIR/const_debuginfo.rs:+1:13: +1:16
61-
StorageLive(_2); // scope 1 at $DIR/const_debuginfo.rs:+2:9: +2:10
6260
_2 = const 2_u8; // scope 1 at $DIR/const_debuginfo.rs:+2:13: +2:16
63-
StorageLive(_3); // scope 2 at $DIR/const_debuginfo.rs:+3:9: +3:10
6461
_3 = const 3_u8; // scope 2 at $DIR/const_debuginfo.rs:+3:13: +3:16
6562
StorageLive(_4); // scope 3 at $DIR/const_debuginfo.rs:+4:9: +4:12
6663
StorageLive(_5); // scope 3 at $DIR/const_debuginfo.rs:+4:15: +4:20

‎tests/mir-opt/const_prop/bad_op_mod_by_zero.main.ConstProp.diff‎

Lines changed: 0 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -18,7 +18,6 @@
1818
}
1919

2020
bb0: {
21-
StorageLive(_1); // scope 0 at $DIR/bad_op_mod_by_zero.rs:+1:9: +1:10
2221
_1 = const 0_i32; // scope 0 at $DIR/bad_op_mod_by_zero.rs:+1:13: +1:14
2322
StorageLive(_2); // scope 1 at $DIR/bad_op_mod_by_zero.rs:+2:9: +2:11
2423
- _4 = Eq(_1, const 0_i32); // scope 1 at $DIR/bad_op_mod_by_zero.rs:+2:14: +2:19

‎tests/mir-opt/const_prop/scalar_literal_propagation.main.ConstProp.diff‎

Lines changed: 0 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -11,7 +11,6 @@
1111
}
1212

1313
bb0: {
14-
StorageLive(_1); // scope 0 at $DIR/scalar_literal_propagation.rs:+1:9: +1:10
1514
_1 = const 1_u32; // scope 0 at $DIR/scalar_literal_propagation.rs:+1:13: +1:14
1615
StorageLive(_2); // scope 1 at $DIR/scalar_literal_propagation.rs:+2:5: +2:15
1716
- _2 = consume(_1) -> bb1; // scope 1 at $DIR/scalar_literal_propagation.rs:+2:5: +2:15

‎tests/mir-opt/copy-prop/cycle.main.CopyProp.diff‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -29,7 +29,7 @@
2929
}
3030

3131
bb1: {
32-
StorageLive(_2); // scope 1 at $DIR/cycle.rs:+2:9: +2:10
32+
- StorageLive(_2); // scope 1 at $DIR/cycle.rs:+2:9: +2:10
3333
_2 = _1; // scope 1 at $DIR/cycle.rs:+2:13: +2:14
3434
- StorageLive(_3); // scope 2 at $DIR/cycle.rs:+3:9: +3:10
3535
- _3 = _2; // scope 2 at $DIR/cycle.rs:+3:13: +3:14

‎tests/mir-opt/copy-prop/dead_stores_79191.f.CopyProp.after.mir‎

Lines changed: 0 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -11,7 +11,6 @@ fn f(_1: usize) -> usize {
1111
}
1212

1313
bb0: {
14-
StorageLive(_2); // scope 0 at $DIR/dead_stores_79191.rs:+1:9: +1:10
1514
_2 = _1; // scope 0 at $DIR/dead_stores_79191.rs:+1:13: +1:14
1615
_1 = const 5_usize; // scope 1 at $DIR/dead_stores_79191.rs:+2:5: +2:10
1716
_1 = _2; // scope 1 at $DIR/dead_stores_79191.rs:+3:5: +3:10

‎tests/mir-opt/copy-prop/dead_stores_better.f.CopyProp.after.mir‎

Lines changed: 0 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -11,7 +11,6 @@ fn f(_1: usize) -> usize {
1111
}
1212

1313
bb0: {
14-
StorageLive(_2); // scope 0 at $DIR/dead_stores_better.rs:+1:9: +1:10
1514
_2 = _1; // scope 0 at $DIR/dead_stores_better.rs:+1:13: +1:14
1615
_1 = const 5_usize; // scope 1 at $DIR/dead_stores_better.rs:+2:5: +2:10
1716
_1 = _2; // scope 1 at $DIR/dead_stores_better.rs:+3:5: +3:10

‎tests/mir-opt/copy-prop/issue_107511.main.CopyProp.diff‎

Lines changed: 140 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,140 @@
1+
- // MIR for `main` before CopyProp
2+
+ // MIR for `main` after CopyProp
3+
4+
fn main() -> () {
5+
let mut _0: (); // return place in scope 0 at $DIR/issue_107511.rs:+0:11: +0:11
6+
let mut _1: i32; // in scope 0 at $DIR/issue_107511.rs:+1:9: +1:16
7+
let mut _3: std::ops::Range<usize>; // in scope 0 at $DIR/issue_107511.rs:+6:14: +6:24
8+
let mut _4: std::ops::Range<usize>; // in scope 0 at $DIR/issue_107511.rs:+6:14: +6:24
9+
let mut _5: usize; // in scope 0 at $DIR/issue_107511.rs:+6:17: +6:24
10+
let mut _6: &[i32]; // in scope 0 at $DIR/issue_107511.rs:+6:17: +6:24
11+
let mut _7: &[i32; 4]; // in scope 0 at $DIR/issue_107511.rs:+6:17: +6:24
12+
let mut _9: (); // in scope 0 at $DIR/issue_107511.rs:+0:1: +9:2
13+
let _10: (); // in scope 0 at $DIR/issue_107511.rs:+6:14: +6:24
14+
let mut _11: std::option::Option<usize>; // in scope 0 at $DIR/issue_107511.rs:+6:14: +6:24
15+
let mut _12: &mut std::ops::Range<usize>; // in scope 0 at $DIR/issue_107511.rs:+6:14: +6:24
16+
let mut _13: &mut std::ops::Range<usize>; // in scope 0 at $DIR/issue_107511.rs:+6:14: +6:24
17+
let mut _14: isize; // in scope 0 at $DIR/issue_107511.rs:+6:5: +8:6
18+
let mut _15: !; // in scope 0 at $DIR/issue_107511.rs:+6:5: +8:6
19+
let mut _17: i32; // in scope 0 at $DIR/issue_107511.rs:+7:16: +7:20
20+
let _18: usize; // in scope 0 at $DIR/issue_107511.rs:+7:18: +7:19
21+
let mut _19: usize; // in scope 0 at $DIR/issue_107511.rs:+7:16: +7:20
22+
let mut _20: bool; // in scope 0 at $DIR/issue_107511.rs:+7:16: +7:20
23+
scope 1 {
24+
debug sum => _1; // in scope 1 at $DIR/issue_107511.rs:+1:9: +1:16
25+
let _2: [i32; 4]; // in scope 1 at $DIR/issue_107511.rs:+2:9: +2:10
26+
scope 2 {
27+
debug a => _2; // in scope 2 at $DIR/issue_107511.rs:+2:9: +2:10
28+
let mut _8: std::ops::Range<usize>; // in scope 2 at $DIR/issue_107511.rs:+6:14: +6:24
29+
scope 3 {
30+
debug iter => _8; // in scope 3 at $DIR/issue_107511.rs:+6:14: +6:24
31+
let _16: usize; // in scope 3 at $DIR/issue_107511.rs:+6:9: +6:10
32+
scope 4 {
33+
debug i => _16; // in scope 4 at $DIR/issue_107511.rs:+6:9: +6:10
34+
}
35+
}
36+
}
37+
}
38+
39+
bb0: {
40+
StorageLive(_1); // scope 0 at $DIR/issue_107511.rs:+1:9: +1:16
41+
_1 = const 0_i32; // scope 0 at $DIR/issue_107511.rs:+1:19: +1:20
42+
StorageLive(_2); // scope 1 at $DIR/issue_107511.rs:+2:9: +2:10
43+
_2 = [const 0_i32, const 10_i32, const 20_i32, const 30_i32]; // scope 1 at $DIR/issue_107511.rs:+2:13: +2:28
44+
StorageLive(_3); // scope 2 at $DIR/issue_107511.rs:+6:14: +6:24
45+
StorageLive(_4); // scope 2 at $DIR/issue_107511.rs:+6:14: +6:24
46+
StorageLive(_5); // scope 2 at $DIR/issue_107511.rs:+6:17: +6:24
47+
StorageLive(_6); // scope 2 at $DIR/issue_107511.rs:+6:17: +6:24
48+
StorageLive(_7); // scope 2 at $DIR/issue_107511.rs:+6:17: +6:24
49+
_7 = &_2; // scope 2 at $DIR/issue_107511.rs:+6:17: +6:24
50+
_6 = move _7 as &[i32] (Pointer(Unsize)); // scope 2 at $DIR/issue_107511.rs:+6:17: +6:24
51+
StorageDead(_7); // scope 2 at $DIR/issue_107511.rs:+6:17: +6:18
52+
_5 = core::slice::<impl [i32]>::len(move _6) -> bb1; // scope 2 at $DIR/issue_107511.rs:+6:17: +6:24
53+
// mir::Constant
54+
// + span: $DIR/issue_107511.rs:10:19: 10:22
55+
// + literal: Const { ty: for<'a> fn(&'a [i32]) -> usize {core::slice::<impl [i32]>::len}, val: Value(<ZST>) }
56+
}
57+
58+
bb1: {
59+
StorageDead(_6); // scope 2 at $DIR/issue_107511.rs:+6:23: +6:24
60+
Deinit(_4); // scope 2 at $DIR/issue_107511.rs:+6:14: +6:24
61+
(_4.0: usize) = const 0_usize; // scope 2 at $DIR/issue_107511.rs:+6:14: +6:24
62+
(_4.1: usize) = move _5; // scope 2 at $DIR/issue_107511.rs:+6:14: +6:24
63+
StorageDead(_5); // scope 2 at $DIR/issue_107511.rs:+6:23: +6:24
64+
_3 = <std::ops::Range<usize> as IntoIterator>::into_iter(move _4) -> bb2; // scope 2 at $DIR/issue_107511.rs:+6:14: +6:24
65+
// mir::Constant
66+
// + span: $DIR/issue_107511.rs:10:14: 10:24
67+
// + literal: Const { ty: fn(std::ops::Range<usize>) -> <std::ops::Range<usize> as IntoIterator>::IntoIter {<std::ops::Range<usize> as IntoIterator>::into_iter}, val: Value(<ZST>) }
68+
}
69+
70+
bb2: {
71+
StorageDead(_4); // scope 2 at $DIR/issue_107511.rs:+6:23: +6:24
72+
StorageLive(_8); // scope 2 at $DIR/issue_107511.rs:+6:14: +6:24
73+
_8 = move _3; // scope 2 at $DIR/issue_107511.rs:+6:14: +6:24
74+
goto -> bb3; // scope 3 at $DIR/issue_107511.rs:+6:5: +8:6
75+
}
76+
77+
bb3: {
78+
- StorageLive(_10); // scope 3 at $DIR/issue_107511.rs:+6:14: +6:24
79+
StorageLive(_11); // scope 3 at $DIR/issue_107511.rs:+6:14: +6:24
80+
StorageLive(_12); // scope 3 at $DIR/issue_107511.rs:+6:14: +6:24
81+
StorageLive(_13); // scope 3 at $DIR/issue_107511.rs:+6:14: +6:24
82+
_13 = &mut _8; // scope 3 at $DIR/issue_107511.rs:+6:14: +6:24
83+
_12 = &mut (*_13); // scope 3 at $DIR/issue_107511.rs:+6:14: +6:24
84+
_11 = <std::ops::Range<usize> as Iterator>::next(move _12) -> bb4; // scope 3 at $DIR/issue_107511.rs:+6:14: +6:24
85+
// mir::Constant
86+
// + span: $DIR/issue_107511.rs:10:14: 10:24
87+
// + literal: Const { ty: for<'a> fn(&'a mut std::ops::Range<usize>) -> Option<<std::ops::Range<usize> as Iterator>::Item> {<std::ops::Range<usize> as Iterator>::next}, val: Value(<ZST>) }
88+
}
89+
90+
bb4: {
91+
StorageDead(_12); // scope 3 at $DIR/issue_107511.rs:+6:23: +6:24
92+
_14 = discriminant(_11); // scope 3 at $DIR/issue_107511.rs:+6:14: +6:24
93+
switchInt(move _14) -> [0: bb7, 1: bb5, otherwise: bb6]; // scope 3 at $DIR/issue_107511.rs:+6:14: +6:24
94+
}
95+
96+
bb5: {
97+
- StorageLive(_16); // scope 3 at $DIR/issue_107511.rs:+6:9: +6:10
98+
_16 = ((_11 as Some).0: usize); // scope 3 at $DIR/issue_107511.rs:+6:9: +6:10
99+
StorageLive(_17); // scope 4 at $DIR/issue_107511.rs:+7:16: +7:20
100+
- StorageLive(_18); // scope 4 at $DIR/issue_107511.rs:+7:18: +7:19
101+
- _18 = _16; // scope 4 at $DIR/issue_107511.rs:+7:18: +7:19
102+
_19 = Len(_2); // scope 4 at $DIR/issue_107511.rs:+7:16: +7:20
103+
- _20 = Lt(_18, _19); // scope 4 at $DIR/issue_107511.rs:+7:16: +7:20
104+
- assert(move _20, "index out of bounds: the length is {} but the index is {}", move _19, _18) -> bb8; // scope 4 at $DIR/issue_107511.rs:+7:16: +7:20
105+
+ _20 = Lt(_16, _19); // scope 4 at $DIR/issue_107511.rs:+7:16: +7:20
106+
+ assert(move _20, "index out of bounds: the length is {} but the index is {}", move _19, _16) -> bb8; // scope 4 at $DIR/issue_107511.rs:+7:16: +7:20
107+
}
108+
109+
bb6: {
110+
unreachable; // scope 3 at $DIR/issue_107511.rs:+6:14: +6:24
111+
}
112+
113+
bb7: {
114+
_0 = const (); // scope 3 at $DIR/issue_107511.rs:+6:5: +8:6
115+
StorageDead(_13); // scope 3 at $DIR/issue_107511.rs:+8:5: +8:6
116+
StorageDead(_11); // scope 3 at $DIR/issue_107511.rs:+8:5: +8:6
117+
- StorageDead(_10); // scope 3 at $DIR/issue_107511.rs:+8:5: +8:6
118+
StorageDead(_8); // scope 2 at $DIR/issue_107511.rs:+8:5: +8:6
119+
StorageDead(_3); // scope 2 at $DIR/issue_107511.rs:+8:5: +8:6
120+
StorageDead(_2); // scope 1 at $DIR/issue_107511.rs:+9:1: +9:2
121+
StorageDead(_1); // scope 0 at $DIR/issue_107511.rs:+9:1: +9:2
122+
return; // scope 0 at $DIR/issue_107511.rs:+9:2: +9:2
123+
}
124+
125+
bb8: {
126+
- _17 = _2[_18]; // scope 4 at $DIR/issue_107511.rs:+7:16: +7:20
127+
+ _17 = _2[_16]; // scope 4 at $DIR/issue_107511.rs:+7:16: +7:20
128+
_1 = Add(_1, move _17); // scope 4 at $DIR/issue_107511.rs:+7:9: +7:20
129+
StorageDead(_17); // scope 4 at $DIR/issue_107511.rs:+7:19: +7:20
130+
- StorageDead(_18); // scope 4 at $DIR/issue_107511.rs:+7:20: +7:21
131+
- _10 = const (); // scope 4 at $DIR/issue_107511.rs:+6:25: +8:6
132+
- StorageDead(_16); // scope 3 at $DIR/issue_107511.rs:+8:5: +8:6
133+
StorageDead(_13); // scope 3 at $DIR/issue_107511.rs:+8:5: +8:6
134+
StorageDead(_11); // scope 3 at $DIR/issue_107511.rs:+8:5: +8:6
135+
- StorageDead(_10); // scope 3 at $DIR/issue_107511.rs:+8:5: +8:6
136+
- _9 = const (); // scope 3 at $DIR/issue_107511.rs:+6:5: +8:6
137+
goto -> bb3; // scope 3 at $DIR/issue_107511.rs:+6:5: +8:6
138+
}
139+
}
140+

‎tests/mir-opt/copy-prop/issue_107511.rs‎

Lines changed: 13 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,13 @@
1+
// unit-test: CopyProp
2+
3+
// EMIT_MIR issue_107511.main.CopyProp.diff
4+
fn main() {
5+
let mut sum = 0;
6+
let a = [0, 10, 20, 30];
7+
8+
// `i` is assigned in a loop. Only removing its `StorageDead` would mean that
9+
// execution sees repeated `StorageLive`. This would be UB.
10+
for i in 0..a.len() {
11+
sum += a[i];
12+
}
13+
}

‎tests/mir-opt/dataflow-const-prop/inherit_overflow.main.DataflowConstProp.diff‎

Lines changed: 0 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -16,9 +16,7 @@
1616
}
1717

1818
bb0: {
19-
StorageLive(_1); // scope 0 at $DIR/inherit_overflow.rs:+3:13: +3:47
2019
_1 = const u8::MAX; // scope 0 at $DIR/inherit_overflow.rs:+3:13: +3:47
21-
StorageLive(_2); // scope 0 at $DIR/inherit_overflow.rs:+3:13: +3:47
2220
_2 = const 1_u8; // scope 0 at $DIR/inherit_overflow.rs:+3:13: +3:47
2321
_5 = CheckedAdd(const u8::MAX, const 1_u8); // scope 2 at $SRC_DIR/core/src/ops/arith.rs:LL:COL
2422
assert(!move (_5.1: bool), "attempt to compute `{} + {}`, which would overflow", const u8::MAX, const 1_u8) -> bb1; // scope 2 at $SRC_DIR/core/src/ops/arith.rs:LL:COL

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