1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
|
use rustc_abi::VariantIdx;
use rustc_middle::mir::{self, Body, Location, Terminator, TerminatorKind};
use tracing::debug;
use super::move_paths::{InitKind, LookupResult, MoveData, MovePathIndex};
/// The value of an inserted drop flag.
#[derive(Debug, PartialEq, Eq, Copy, Clone)]
pub enum DropFlagState {
/// The tracked value is initialized and needs to be dropped when leaving its scope.
Present,
/// The tracked value is uninitialized or was moved out of and does not need to be dropped when
/// leaving its scope.
Absent,
}
impl DropFlagState {
pub fn value(self) -> bool {
match self {
DropFlagState::Present => true,
DropFlagState::Absent => false,
}
}
}
pub fn move_path_children_matching<'tcx, F>(
move_data: &MoveData<'tcx>,
path: MovePathIndex,
mut cond: F,
) -> Option<MovePathIndex>
where
F: FnMut(mir::PlaceElem<'tcx>) -> bool,
{
let mut next_child = move_data.move_paths[path].first_child;
while let Some(child_index) = next_child {
let move_path_children = &move_data.move_paths[child_index];
if let Some(&elem) = move_path_children.place.projection.last() {
if cond(elem) {
return Some(child_index);
}
}
next_child = move_path_children.next_sibling;
}
None
}
pub fn on_lookup_result_bits<'tcx, F>(
move_data: &MoveData<'tcx>,
lookup_result: LookupResult,
each_child: F,
) where
F: FnMut(MovePathIndex),
{
match lookup_result {
LookupResult::Parent(..) => {
// access to untracked value - do not touch children
}
LookupResult::Exact(e) => on_all_children_bits(move_data, e, each_child),
}
}
pub fn on_all_children_bits<'tcx, F>(
move_data: &MoveData<'tcx>,
move_path_index: MovePathIndex,
mut each_child: F,
) where
F: FnMut(MovePathIndex),
{
fn on_all_children_bits<'tcx, F>(
move_data: &MoveData<'tcx>,
move_path_index: MovePathIndex,
each_child: &mut F,
) where
F: FnMut(MovePathIndex),
{
each_child(move_path_index);
let mut next_child_index = move_data.move_paths[move_path_index].first_child;
while let Some(child_index) = next_child_index {
on_all_children_bits(move_data, child_index, each_child);
next_child_index = move_data.move_paths[child_index].next_sibling;
}
}
on_all_children_bits(move_data, move_path_index, &mut each_child);
}
pub fn drop_flag_effects_for_function_entry<'tcx, F>(
body: &Body<'tcx>,
move_data: &MoveData<'tcx>,
mut callback: F,
) where
F: FnMut(MovePathIndex, DropFlagState),
{
for arg in body.args_iter() {
let place = mir::Place::from(arg);
let lookup_result = move_data.rev_lookup.find(place.as_ref());
on_lookup_result_bits(move_data, lookup_result, |mpi| {
callback(mpi, DropFlagState::Present)
});
}
}
pub fn drop_flag_effects_for_location<'tcx, F>(
body: &Body<'tcx>,
move_data: &MoveData<'tcx>,
loc: Location,
mut callback: F,
) where
F: FnMut(MovePathIndex, DropFlagState),
{
debug!("drop_flag_effects_for_location({:?})", loc);
// first, move out of the RHS
for mi in &move_data.loc_map[loc] {
let path = mi.move_path_index(move_data);
debug!("moving out of path {:?}", move_data.move_paths[path]);
on_all_children_bits(move_data, path, |mpi| callback(mpi, DropFlagState::Absent))
}
// Drop does not count as a move but we should still consider the variable uninitialized.
if let Some(Terminator { kind: TerminatorKind::Drop { place, .. }, .. }) =
body.stmt_at(loc).right()
{
if let LookupResult::Exact(mpi) = move_data.rev_lookup.find(place.as_ref()) {
on_all_children_bits(move_data, mpi, |mpi| callback(mpi, DropFlagState::Absent))
}
}
debug!("drop_flag_effects: assignment for location({:?})", loc);
for_location_inits(move_data, loc, |mpi| callback(mpi, DropFlagState::Present));
}
fn for_location_inits<'tcx, F>(move_data: &MoveData<'tcx>, loc: Location, mut callback: F)
where
F: FnMut(MovePathIndex),
{
for ii in &move_data.init_loc_map[loc] {
let init = move_data.inits[*ii];
match init.kind {
InitKind::Deep => {
let path = init.path;
on_all_children_bits(move_data, path, &mut callback)
}
InitKind::Shallow => {
let mpi = init.path;
callback(mpi);
}
InitKind::NonPanicPathOnly => (),
}
}
}
/// Calls `handle_inactive_variant` for each descendant move path of `enum_place` that contains a
/// `Downcast` to a variant besides the `active_variant`.
///
/// NOTE: If there are no move paths corresponding to an inactive variant,
/// `handle_inactive_variant` will not be called for that variant.
pub(crate) fn on_all_inactive_variants<'tcx>(
move_data: &MoveData<'tcx>,
enum_place: mir::Place<'tcx>,
active_variant: VariantIdx,
mut handle_inactive_variant: impl FnMut(MovePathIndex),
) {
let LookupResult::Exact(enum_mpi) = move_data.rev_lookup.find(enum_place.as_ref()) else {
return;
};
let enum_path = &move_data.move_paths[enum_mpi];
for (variant_mpi, variant_path) in enum_path.children(&move_data.move_paths) {
// Because of the way we build the `MoveData` tree, each child should have exactly one more
// projection than `enum_place`. This additional projection must be a downcast since the
// base is an enum.
let (downcast, base_proj) = variant_path.place.projection.split_last().unwrap();
assert_eq!(enum_place.projection.len(), base_proj.len());
let mir::ProjectionElem::Downcast(_, variant_idx) = *downcast else {
unreachable!();
};
if variant_idx != active_variant {
on_all_children_bits(move_data, variant_mpi, |mpi| handle_inactive_variant(mpi));
}
}
}
|
