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Commit | Line | Data |
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dfeec247 | 1 | use crate::util::patch::MirPatch; |
dfeec247 | 2 | use rustc_hir as hir; |
3dfed10e | 3 | use rustc_hir::lang_items::LangItem; |
e74abb32 | 4 | use rustc_index::vec::Idx; |
ba9703b0 XL |
5 | use rustc_middle::mir::*; |
6 | use rustc_middle::traits::Reveal; | |
7 | use rustc_middle::ty::subst::SubstsRef; | |
8 | use rustc_middle::ty::util::IntTypeExt; | |
9 | use rustc_middle::ty::{self, Ty, TyCtxt}; | |
10 | use rustc_target::abi::VariantIdx; | |
dfeec247 | 11 | use std::fmt; |
cc61c64b | 12 | |
f9f354fc | 13 | /// The value of an inserted drop flag. |
cc61c64b XL |
14 | #[derive(Debug, PartialEq, Eq, Copy, Clone)] |
15 | pub enum DropFlagState { | |
f9f354fc XL |
16 | /// The tracked value is initialized and needs to be dropped when leaving its scope. |
17 | Present, | |
18 | ||
19 | /// The tracked value is uninitialized or was moved out of and does not need to be dropped when | |
20 | /// leaving its scope. | |
21 | Absent, | |
cc61c64b XL |
22 | } |
23 | ||
24 | impl DropFlagState { | |
25 | pub fn value(self) -> bool { | |
26 | match self { | |
27 | DropFlagState::Present => true, | |
dfeec247 | 28 | DropFlagState::Absent => false, |
cc61c64b XL |
29 | } |
30 | } | |
31 | } | |
32 | ||
f9f354fc | 33 | /// Describes how/if a value should be dropped. |
cc61c64b XL |
34 | #[derive(Debug)] |
35 | pub enum DropStyle { | |
f9f354fc | 36 | /// The value is already dead at the drop location, no drop will be executed. |
cc61c64b | 37 | Dead, |
f9f354fc XL |
38 | |
39 | /// The value is known to always be initialized at the drop location, drop will always be | |
40 | /// executed. | |
cc61c64b | 41 | Static, |
f9f354fc XL |
42 | |
43 | /// Whether the value needs to be dropped depends on its drop flag. | |
cc61c64b | 44 | Conditional, |
f9f354fc XL |
45 | |
46 | /// An "open" drop is one where only the fields of a value are dropped. | |
47 | /// | |
48 | /// For example, this happens when moving out of a struct field: The rest of the struct will be | |
49 | /// dropped in such an "open" drop. It is also used to generate drop glue for the individual | |
50 | /// components of a value, for example for dropping array elements. | |
cc61c64b XL |
51 | Open, |
52 | } | |
53 | ||
f9f354fc | 54 | /// Which drop flags to affect/check with an operation. |
cc61c64b XL |
55 | #[derive(Debug)] |
56 | pub enum DropFlagMode { | |
f9f354fc | 57 | /// Only affect the top-level drop flag, not that of any contained fields. |
cc61c64b | 58 | Shallow, |
f9f354fc | 59 | /// Affect all nested drop flags in addition to the top-level one. |
dfeec247 | 60 | Deep, |
cc61c64b XL |
61 | } |
62 | ||
f9f354fc | 63 | /// Describes if unwinding is necessary and where to unwind to if a panic occurs. |
7cac9316 XL |
64 | #[derive(Copy, Clone, Debug)] |
65 | pub enum Unwind { | |
f9f354fc | 66 | /// Unwind to this block. |
7cac9316 | 67 | To(BasicBlock), |
f9f354fc | 68 | /// Already in an unwind path, any panic will cause an abort. |
dfeec247 | 69 | InCleanup, |
7cac9316 XL |
70 | } |
71 | ||
72 | impl Unwind { | |
73 | fn is_cleanup(self) -> bool { | |
74 | match self { | |
75 | Unwind::To(..) => false, | |
dfeec247 | 76 | Unwind::InCleanup => true, |
7cac9316 XL |
77 | } |
78 | } | |
79 | ||
80 | fn into_option(self) -> Option<BasicBlock> { | |
81 | match self { | |
82 | Unwind::To(bb) => Some(bb), | |
83 | Unwind::InCleanup => None, | |
84 | } | |
85 | } | |
86 | ||
dfeec247 XL |
87 | fn map<F>(self, f: F) -> Self |
88 | where | |
89 | F: FnOnce(BasicBlock) -> BasicBlock, | |
90 | { | |
7cac9316 XL |
91 | match self { |
92 | Unwind::To(bb) => Unwind::To(f(bb)), | |
dfeec247 | 93 | Unwind::InCleanup => Unwind::InCleanup, |
7cac9316 XL |
94 | } |
95 | } | |
96 | } | |
97 | ||
dc9dc135 | 98 | pub trait DropElaborator<'a, 'tcx>: fmt::Debug { |
f9f354fc XL |
99 | /// The type representing paths that can be moved out of. |
100 | /// | |
101 | /// Users can move out of individual fields of a struct, such as `a.b.c`. This type is used to | |
102 | /// represent such move paths. Sometimes tracking individual move paths is not necessary, in | |
103 | /// which case this may be set to (for example) `()`. | |
dfeec247 | 104 | type Path: Copy + fmt::Debug; |
cc61c64b | 105 | |
f9f354fc XL |
106 | // Accessors |
107 | ||
cc61c64b | 108 | fn patch(&mut self) -> &mut MirPatch<'tcx>; |
dc9dc135 XL |
109 | fn body(&self) -> &'a Body<'tcx>; |
110 | fn tcx(&self) -> TyCtxt<'tcx>; | |
7cac9316 | 111 | fn param_env(&self) -> ty::ParamEnv<'tcx>; |
cc61c64b | 112 | |
f9f354fc XL |
113 | // Drop logic |
114 | ||
115 | /// Returns how `path` should be dropped, given `mode`. | |
cc61c64b | 116 | fn drop_style(&self, path: Self::Path, mode: DropFlagMode) -> DropStyle; |
f9f354fc XL |
117 | |
118 | /// Returns the drop flag of `path` as a MIR `Operand` (or `None` if `path` has no drop flag). | |
cc61c64b | 119 | fn get_drop_flag(&mut self, path: Self::Path) -> Option<Operand<'tcx>>; |
f9f354fc XL |
120 | |
121 | /// Modifies the MIR patch so that the drop flag of `path` (if any) is cleared at `location`. | |
122 | /// | |
123 | /// If `mode` is deep, drop flags of all child paths should also be cleared by inserting | |
124 | /// additional statements. | |
cc61c64b XL |
125 | fn clear_drop_flag(&mut self, location: Location, path: Self::Path, mode: DropFlagMode); |
126 | ||
f9f354fc XL |
127 | // Subpaths |
128 | ||
129 | /// Returns the subpath of a field of `path` (or `None` if there is no dedicated subpath). | |
130 | /// | |
131 | /// If this returns `None`, `field` will not get a dedicated drop flag. | |
cc61c64b | 132 | fn field_subpath(&self, path: Self::Path, field: Field) -> Option<Self::Path>; |
f9f354fc XL |
133 | |
134 | /// Returns the subpath of a dereference of `path` (or `None` if there is no dedicated subpath). | |
135 | /// | |
136 | /// If this returns `None`, `*path` will not get a dedicated drop flag. | |
137 | /// | |
138 | /// This is only relevant for `Box<T>`, where the contained `T` can be moved out of the box. | |
cc61c64b | 139 | fn deref_subpath(&self, path: Self::Path) -> Option<Self::Path>; |
f9f354fc XL |
140 | |
141 | /// Returns the subpath of downcasting `path` to one of its variants. | |
142 | /// | |
143 | /// If this returns `None`, the downcast of `path` will not get a dedicated drop flag. | |
a1dfa0c6 | 144 | fn downcast_subpath(&self, path: Self::Path, variant: VariantIdx) -> Option<Self::Path>; |
f9f354fc XL |
145 | |
146 | /// Returns the subpath of indexing a fixed-size array `path`. | |
147 | /// | |
148 | /// If this returns `None`, elements of `path` will not get a dedicated drop flag. | |
149 | /// | |
150 | /// This is only relevant for array patterns, which can move out of individual array elements. | |
1b1a35ee | 151 | fn array_subpath(&self, path: Self::Path, index: u64, size: u64) -> Option<Self::Path>; |
cc61c64b XL |
152 | } |
153 | ||
154 | #[derive(Debug)] | |
dc9dc135 XL |
155 | struct DropCtxt<'l, 'b, 'tcx, D> |
156 | where | |
157 | D: DropElaborator<'b, 'tcx>, | |
cc61c64b XL |
158 | { |
159 | elaborator: &'l mut D, | |
160 | ||
161 | source_info: SourceInfo, | |
cc61c64b | 162 | |
ba9703b0 | 163 | place: Place<'tcx>, |
cc61c64b XL |
164 | path: D::Path, |
165 | succ: BasicBlock, | |
7cac9316 | 166 | unwind: Unwind, |
cc61c64b XL |
167 | } |
168 | ||
f9f354fc XL |
169 | /// "Elaborates" a drop of `place`/`path` and patches `bb`'s terminator to execute it. |
170 | /// | |
171 | /// The passed `elaborator` is used to determine what should happen at the drop terminator. It | |
172 | /// decides whether the drop can be statically determined or whether it needs a dynamic drop flag, | |
173 | /// and whether the drop is "open", ie. should be expanded to drop all subfields of the dropped | |
174 | /// value. | |
175 | /// | |
176 | /// When this returns, the MIR patch in the `elaborator` contains the necessary changes. | |
cc61c64b XL |
177 | pub fn elaborate_drop<'b, 'tcx, D>( |
178 | elaborator: &mut D, | |
179 | source_info: SourceInfo, | |
ba9703b0 | 180 | place: Place<'tcx>, |
cc61c64b XL |
181 | path: D::Path, |
182 | succ: BasicBlock, | |
7cac9316 | 183 | unwind: Unwind, |
dc9dc135 XL |
184 | bb: BasicBlock, |
185 | ) where | |
186 | D: DropElaborator<'b, 'tcx>, | |
187 | 'tcx: 'b, | |
cc61c64b | 188 | { |
dfeec247 | 189 | DropCtxt { elaborator, source_info, place, path, succ, unwind }.elaborate_drop(bb) |
cc61c64b XL |
190 | } |
191 | ||
192 | impl<'l, 'b, 'tcx, D> DropCtxt<'l, 'b, 'tcx, D> | |
dc9dc135 XL |
193 | where |
194 | D: DropElaborator<'b, 'tcx>, | |
195 | 'tcx: 'b, | |
cc61c64b | 196 | { |
ba9703b0 | 197 | fn place_ty(&self, place: Place<'tcx>) -> Ty<'tcx> { |
dc9dc135 | 198 | place.ty(self.elaborator.body(), self.tcx()).ty |
cc61c64b XL |
199 | } |
200 | ||
dc9dc135 | 201 | fn tcx(&self) -> TyCtxt<'tcx> { |
cc61c64b XL |
202 | self.elaborator.tcx() |
203 | } | |
204 | ||
205 | /// This elaborates a single drop instruction, located at `bb`, and | |
206 | /// patches over it. | |
207 | /// | |
208 | /// The elaborated drop checks the drop flags to only drop what | |
209 | /// is initialized. | |
210 | /// | |
211 | /// In addition, the relevant drop flags also need to be cleared | |
212 | /// to avoid double-drops. However, in the middle of a complex | |
213 | /// drop, one must avoid clearing some of the flags before they | |
214 | /// are read, as that would cause a memory leak. | |
215 | /// | |
216 | /// In particular, when dropping an ADT, multiple fields may be | |
217 | /// joined together under the `rest` subpath. They are all controlled | |
218 | /// by the primary drop flag, but only the last rest-field dropped | |
219 | /// should clear it (and it must also not clear anything else). | |
9fa01778 XL |
220 | // |
221 | // FIXME: I think we should just control the flags externally, | |
222 | // and then we do not need this machinery. | |
dc9dc135 | 223 | pub fn elaborate_drop(&mut self, bb: BasicBlock) { |
74b04a01 | 224 | debug!("elaborate_drop({:?}, {:?})", bb, self); |
cc61c64b | 225 | let style = self.elaborator.drop_style(self.path, DropFlagMode::Deep); |
74b04a01 | 226 | debug!("elaborate_drop({:?}, {:?}): live - {:?}", bb, self, style); |
cc61c64b XL |
227 | match style { |
228 | DropStyle::Dead => { | |
dfeec247 XL |
229 | self.elaborator |
230 | .patch() | |
231 | .patch_terminator(bb, TerminatorKind::Goto { target: self.succ }); | |
cc61c64b XL |
232 | } |
233 | DropStyle::Static => { | |
dfeec247 XL |
234 | self.elaborator.patch().patch_terminator( |
235 | bb, | |
236 | TerminatorKind::Drop { | |
f035d41b | 237 | place: self.place, |
dfeec247 XL |
238 | target: self.succ, |
239 | unwind: self.unwind.into_option(), | |
240 | }, | |
241 | ); | |
cc61c64b XL |
242 | } |
243 | DropStyle::Conditional => { | |
29967ef6 | 244 | let drop_bb = self.complete_drop(self.succ, self.unwind); |
dfeec247 XL |
245 | self.elaborator |
246 | .patch() | |
247 | .patch_terminator(bb, TerminatorKind::Goto { target: drop_bb }); | |
cc61c64b XL |
248 | } |
249 | DropStyle::Open => { | |
250 | let drop_bb = self.open_drop(); | |
dfeec247 XL |
251 | self.elaborator |
252 | .patch() | |
253 | .patch_terminator(bb, TerminatorKind::Goto { target: drop_bb }); | |
cc61c64b XL |
254 | } |
255 | } | |
256 | } | |
257 | ||
9fa01778 | 258 | /// Returns the place and move path for each field of `variant`, |
cc61c64b | 259 | /// (the move path is `None` if the field is a rest field). |
dfeec247 XL |
260 | fn move_paths_for_fields( |
261 | &self, | |
ba9703b0 | 262 | base_place: Place<'tcx>, |
dfeec247 XL |
263 | variant_path: D::Path, |
264 | variant: &'tcx ty::VariantDef, | |
265 | substs: SubstsRef<'tcx>, | |
266 | ) -> Vec<(Place<'tcx>, Option<D::Path>)> { | |
267 | variant | |
268 | .fields | |
269 | .iter() | |
270 | .enumerate() | |
271 | .map(|(i, f)| { | |
272 | let field = Field::new(i); | |
273 | let subpath = self.elaborator.field_subpath(variant_path, field); | |
274 | let tcx = self.tcx(); | |
275 | ||
f035d41b | 276 | assert_eq!(self.elaborator.param_env().reveal(), Reveal::All); |
dfeec247 XL |
277 | let field_ty = |
278 | tcx.normalize_erasing_regions(self.elaborator.param_env(), f.ty(tcx, substs)); | |
ba9703b0 | 279 | (tcx.mk_place_field(base_place, field, field_ty), subpath) |
dfeec247 XL |
280 | }) |
281 | .collect() | |
cc61c64b XL |
282 | } |
283 | ||
dfeec247 XL |
284 | fn drop_subpath( |
285 | &mut self, | |
ba9703b0 | 286 | place: Place<'tcx>, |
dfeec247 XL |
287 | path: Option<D::Path>, |
288 | succ: BasicBlock, | |
289 | unwind: Unwind, | |
290 | ) -> BasicBlock { | |
cc61c64b | 291 | if let Some(path) = path { |
ff7c6d11 | 292 | debug!("drop_subpath: for std field {:?}", place); |
cc61c64b XL |
293 | |
294 | DropCtxt { | |
295 | elaborator: self.elaborator, | |
296 | source_info: self.source_info, | |
dfeec247 XL |
297 | path, |
298 | place, | |
299 | succ, | |
300 | unwind, | |
301 | } | |
302 | .elaborated_drop_block() | |
cc61c64b | 303 | } else { |
ff7c6d11 | 304 | debug!("drop_subpath: for rest field {:?}", place); |
cc61c64b XL |
305 | |
306 | DropCtxt { | |
307 | elaborator: self.elaborator, | |
308 | source_info: self.source_info, | |
dfeec247 XL |
309 | place, |
310 | succ, | |
311 | unwind, | |
cc61c64b XL |
312 | // Using `self.path` here to condition the drop on |
313 | // our own drop flag. | |
dfeec247 XL |
314 | path: self.path, |
315 | } | |
29967ef6 | 316 | .complete_drop(succ, unwind) |
cc61c64b XL |
317 | } |
318 | } | |
319 | ||
9fa01778 | 320 | /// Creates one-half of the drop ladder for a list of fields, and return |
7cac9316 XL |
321 | /// the list of steps in it in reverse order, with the first step |
322 | /// dropping 0 fields and so on. | |
cc61c64b XL |
323 | /// |
324 | /// `unwind_ladder` is such a list of steps in reverse order, | |
7cac9316 | 325 | /// which is called if the matching step of the drop glue panics. |
dfeec247 XL |
326 | fn drop_halfladder( |
327 | &mut self, | |
328 | unwind_ladder: &[Unwind], | |
329 | mut succ: BasicBlock, | |
330 | fields: &[(Place<'tcx>, Option<D::Path>)], | |
331 | ) -> Vec<BasicBlock> { | |
332 | Some(succ) | |
333 | .into_iter() | |
ba9703b0 XL |
334 | .chain(fields.iter().rev().zip(unwind_ladder).map(|(&(place, path), &unwind_succ)| { |
335 | succ = self.drop_subpath(place, path, succ, unwind_succ); | |
336 | succ | |
337 | })) | |
dfeec247 | 338 | .collect() |
7cac9316 | 339 | } |
cc61c64b | 340 | |
7cac9316 XL |
341 | fn drop_ladder_bottom(&mut self) -> (BasicBlock, Unwind) { |
342 | // Clear the "master" drop flag at the end. This is needed | |
343 | // because the "master" drop protects the ADT's discriminant, | |
344 | // which is invalidated after the ADT is dropped. | |
29967ef6 | 345 | (self.drop_flag_reset_block(DropFlagMode::Shallow, self.succ, self.unwind), self.unwind) |
cc61c64b XL |
346 | } |
347 | ||
9fa01778 | 348 | /// Creates a full drop ladder, consisting of 2 connected half-drop-ladders |
cc61c64b XL |
349 | /// |
350 | /// For example, with 3 fields, the drop ladder is | |
351 | /// | |
352 | /// .d0: | |
353 | /// ELAB(drop location.0 [target=.d1, unwind=.c1]) | |
354 | /// .d1: | |
355 | /// ELAB(drop location.1 [target=.d2, unwind=.c2]) | |
356 | /// .d2: | |
357 | /// ELAB(drop location.2 [target=`self.succ`, unwind=`self.unwind`]) | |
358 | /// .c1: | |
359 | /// ELAB(drop location.1 [target=.c2]) | |
360 | /// .c2: | |
361 | /// ELAB(drop location.2 [target=`self.unwind`]) | |
7cac9316 XL |
362 | /// |
363 | /// NOTE: this does not clear the master drop flag, so you need | |
364 | /// to point succ/unwind on a `drop_ladder_bottom`. | |
dc9dc135 XL |
365 | fn drop_ladder( |
366 | &mut self, | |
367 | fields: Vec<(Place<'tcx>, Option<D::Path>)>, | |
368 | succ: BasicBlock, | |
369 | unwind: Unwind, | |
370 | ) -> (BasicBlock, Unwind) { | |
cc61c64b XL |
371 | debug!("drop_ladder({:?}, {:?})", self, fields); |
372 | ||
373 | let mut fields = fields; | |
ba9703b0 | 374 | fields.retain(|&(place, _)| { |
ff7c6d11 | 375 | self.place_ty(place).needs_drop(self.tcx(), self.elaborator.param_env()) |
cc61c64b XL |
376 | }); |
377 | ||
378 | debug!("drop_ladder - fields needing drop: {:?}", fields); | |
379 | ||
7cac9316 XL |
380 | let unwind_ladder = vec![Unwind::InCleanup; fields.len() + 1]; |
381 | let unwind_ladder: Vec<_> = if let Unwind::To(target) = unwind { | |
382 | let halfladder = self.drop_halfladder(&unwind_ladder, target, &fields); | |
383 | halfladder.into_iter().map(Unwind::To).collect() | |
cc61c64b | 384 | } else { |
7cac9316 | 385 | unwind_ladder |
cc61c64b XL |
386 | }; |
387 | ||
dfeec247 | 388 | let normal_ladder = self.drop_halfladder(&unwind_ladder, succ, &fields); |
cc61c64b | 389 | |
7cac9316 | 390 | (*normal_ladder.last().unwrap(), *unwind_ladder.last().unwrap()) |
cc61c64b XL |
391 | } |
392 | ||
dc9dc135 | 393 | fn open_drop_for_tuple(&mut self, tys: &[Ty<'tcx>]) -> BasicBlock { |
cc61c64b XL |
394 | debug!("open_drop_for_tuple({:?}, {:?})", self, tys); |
395 | ||
dfeec247 XL |
396 | let fields = tys |
397 | .iter() | |
398 | .enumerate() | |
399 | .map(|(i, &ty)| { | |
400 | ( | |
ba9703b0 | 401 | self.tcx().mk_place_field(self.place, Field::new(i), ty), |
dfeec247 XL |
402 | self.elaborator.field_subpath(self.path, Field::new(i)), |
403 | ) | |
404 | }) | |
405 | .collect(); | |
cc61c64b | 406 | |
7cac9316 XL |
407 | let (succ, unwind) = self.drop_ladder_bottom(); |
408 | self.drop_ladder(fields, succ, unwind).0 | |
cc61c64b XL |
409 | } |
410 | ||
dc9dc135 | 411 | fn open_drop_for_box(&mut self, adt: &'tcx ty::AdtDef, substs: SubstsRef<'tcx>) -> BasicBlock { |
83c7162d | 412 | debug!("open_drop_for_box({:?}, {:?}, {:?})", self, adt, substs); |
cc61c64b | 413 | |
ba9703b0 | 414 | let interior = self.tcx().mk_place_deref(self.place); |
cc61c64b XL |
415 | let interior_path = self.elaborator.deref_subpath(self.path); |
416 | ||
f9f354fc | 417 | let succ = self.box_free_block(adt, substs, self.succ, self.unwind); |
dfeec247 XL |
418 | let unwind_succ = |
419 | self.unwind.map(|unwind| self.box_free_block(adt, substs, unwind, Unwind::InCleanup)); | |
cc61c64b | 420 | |
ba9703b0 | 421 | self.drop_subpath(interior, interior_path, succ, unwind_succ) |
cc61c64b XL |
422 | } |
423 | ||
dc9dc135 | 424 | fn open_drop_for_adt(&mut self, adt: &'tcx ty::AdtDef, substs: SubstsRef<'tcx>) -> BasicBlock { |
cc61c64b | 425 | debug!("open_drop_for_adt({:?}, {:?}, {:?})", self, adt, substs); |
74b04a01 | 426 | if adt.variants.is_empty() { |
cc61c64b XL |
427 | return self.elaborator.patch().new_block(BasicBlockData { |
428 | statements: vec![], | |
429 | terminator: Some(Terminator { | |
430 | source_info: self.source_info, | |
dfeec247 | 431 | kind: TerminatorKind::Unreachable, |
cc61c64b | 432 | }), |
dfeec247 | 433 | is_cleanup: self.unwind.is_cleanup(), |
cc61c64b XL |
434 | }); |
435 | } | |
436 | ||
8faf50e0 XL |
437 | let skip_contents = |
438 | adt.is_union() || Some(adt.did) == self.tcx().lang_items().manually_drop(); | |
439 | let contents_drop = if skip_contents { | |
cc61c64b XL |
440 | (self.succ, self.unwind) |
441 | } else { | |
442 | self.open_drop_for_adt_contents(adt, substs) | |
443 | }; | |
444 | ||
445 | if adt.has_dtor(self.tcx()) { | |
446 | self.destructor_call_block(contents_drop) | |
447 | } else { | |
448 | contents_drop.0 | |
449 | } | |
450 | } | |
451 | ||
dfeec247 XL |
452 | fn open_drop_for_adt_contents( |
453 | &mut self, | |
454 | adt: &'tcx ty::AdtDef, | |
455 | substs: SubstsRef<'tcx>, | |
456 | ) -> (BasicBlock, Unwind) { | |
7cac9316 | 457 | let (succ, unwind) = self.drop_ladder_bottom(); |
ff7c6d11 | 458 | if !adt.is_enum() { |
7cac9316 | 459 | let fields = self.move_paths_for_fields( |
ff7c6d11 | 460 | self.place, |
7cac9316 | 461 | self.path, |
a1dfa0c6 | 462 | &adt.variants[VariantIdx::new(0)], |
dfeec247 | 463 | substs, |
7cac9316 XL |
464 | ); |
465 | self.drop_ladder(fields, succ, unwind) | |
466 | } else { | |
467 | self.open_drop_for_multivariant(adt, substs, succ, unwind) | |
468 | } | |
469 | } | |
470 | ||
dfeec247 XL |
471 | fn open_drop_for_multivariant( |
472 | &mut self, | |
473 | adt: &'tcx ty::AdtDef, | |
474 | substs: SubstsRef<'tcx>, | |
475 | succ: BasicBlock, | |
476 | unwind: Unwind, | |
477 | ) -> (BasicBlock, Unwind) { | |
7cac9316 XL |
478 | let mut values = Vec::with_capacity(adt.variants.len()); |
479 | let mut normal_blocks = Vec::with_capacity(adt.variants.len()); | |
dfeec247 XL |
480 | let mut unwind_blocks = |
481 | if unwind.is_cleanup() { None } else { Some(Vec::with_capacity(adt.variants.len())) }; | |
cc61c64b | 482 | |
74b04a01 | 483 | let mut have_otherwise_with_drop_glue = false; |
7cac9316 | 484 | let mut have_otherwise = false; |
e74abb32 | 485 | let tcx = self.tcx(); |
7cac9316 | 486 | |
e74abb32 | 487 | for (variant_index, discr) in adt.discriminants(tcx) { |
74b04a01 | 488 | let variant = &adt.variants[variant_index]; |
dfeec247 | 489 | let subpath = self.elaborator.downcast_subpath(self.path, variant_index); |
74b04a01 | 490 | |
7cac9316 | 491 | if let Some(variant_path) = subpath { |
e74abb32 | 492 | let base_place = tcx.mk_place_elem( |
ba9703b0 | 493 | self.place, |
74b04a01 | 494 | ProjectionElem::Downcast(Some(variant.ident.name), variant_index), |
dfeec247 | 495 | ); |
ba9703b0 | 496 | let fields = self.move_paths_for_fields(base_place, variant_path, &variant, substs); |
0531ce1d | 497 | values.push(discr.val); |
7cac9316 XL |
498 | if let Unwind::To(unwind) = unwind { |
499 | // We can't use the half-ladder from the original | |
500 | // drop ladder, because this breaks the | |
501 | // "funclet can't have 2 successor funclets" | |
502 | // requirement from MSVC: | |
503 | // | |
504 | // switch unwind-switch | |
505 | // / \ / \ | |
506 | // v1.0 v2.0 v2.0-unwind v1.0-unwind | |
507 | // | | / | | |
508 | // v1.1-unwind v2.1-unwind | | |
509 | // ^ | | |
510 | // \-------------------------------/ | |
511 | // | |
512 | // Create a duplicate half-ladder to avoid that. We | |
513 | // could technically only do this on MSVC, but I | |
514 | // I want to minimize the divergence between MSVC | |
515 | // and non-MSVC. | |
516 | ||
517 | let unwind_blocks = unwind_blocks.as_mut().unwrap(); | |
518 | let unwind_ladder = vec![Unwind::InCleanup; fields.len() + 1]; | |
dfeec247 | 519 | let halfladder = self.drop_halfladder(&unwind_ladder, unwind, &fields); |
7cac9316 | 520 | unwind_blocks.push(halfladder.last().cloned().unwrap()); |
cc61c64b | 521 | } |
7cac9316 XL |
522 | let (normal, _) = self.drop_ladder(fields, succ, unwind); |
523 | normal_blocks.push(normal); | |
524 | } else { | |
525 | have_otherwise = true; | |
74b04a01 XL |
526 | |
527 | let param_env = self.elaborator.param_env(); | |
528 | let have_field_with_drop_glue = variant | |
529 | .fields | |
530 | .iter() | |
531 | .any(|field| field.ty(tcx, substs).needs_drop(tcx, param_env)); | |
532 | if have_field_with_drop_glue { | |
533 | have_otherwise_with_drop_glue = true; | |
534 | } | |
7cac9316 XL |
535 | } |
536 | } | |
cc61c64b | 537 | |
74b04a01 XL |
538 | if !have_otherwise { |
539 | values.pop(); | |
540 | } else if !have_otherwise_with_drop_glue { | |
541 | normal_blocks.push(self.goto_block(succ, unwind)); | |
542 | if let Unwind::To(unwind) = unwind { | |
543 | unwind_blocks.as_mut().unwrap().push(self.goto_block(unwind, Unwind::InCleanup)); | |
544 | } | |
545 | } else { | |
7cac9316 XL |
546 | normal_blocks.push(self.drop_block(succ, unwind)); |
547 | if let Unwind::To(unwind) = unwind { | |
dfeec247 | 548 | unwind_blocks.as_mut().unwrap().push(self.drop_block(unwind, Unwind::InCleanup)); |
cc61c64b XL |
549 | } |
550 | } | |
7cac9316 | 551 | |
dfeec247 XL |
552 | ( |
553 | self.adt_switch_block(adt, normal_blocks, &values, succ, unwind), | |
554 | unwind.map(|unwind| { | |
555 | self.adt_switch_block( | |
556 | adt, | |
557 | unwind_blocks.unwrap(), | |
558 | &values, | |
559 | unwind, | |
560 | Unwind::InCleanup, | |
561 | ) | |
562 | }), | |
563 | ) | |
564 | } | |
565 | ||
566 | fn adt_switch_block( | |
567 | &mut self, | |
568 | adt: &'tcx ty::AdtDef, | |
569 | blocks: Vec<BasicBlock>, | |
570 | values: &[u128], | |
571 | succ: BasicBlock, | |
572 | unwind: Unwind, | |
573 | ) -> BasicBlock { | |
cc61c64b XL |
574 | // If there are multiple variants, then if something |
575 | // is present within the enum the discriminant, tracked | |
576 | // by the rest path, must be initialized. | |
577 | // | |
578 | // Additionally, we do not want to switch on the | |
579 | // discriminant after it is free-ed, because that | |
580 | // way lies only trouble. | |
581 | let discr_ty = adt.repr.discr_type().to_ty(self.tcx()); | |
dc9dc135 | 582 | let discr = Place::from(self.new_temp(discr_ty)); |
ba9703b0 | 583 | let discr_rv = Rvalue::Discriminant(self.place); |
7cac9316 | 584 | let switch_block = BasicBlockData { |
ba9703b0 | 585 | statements: vec![self.assign(discr, discr_rv)], |
cc61c64b XL |
586 | terminator: Some(Terminator { |
587 | source_info: self.source_info, | |
588 | kind: TerminatorKind::SwitchInt { | |
ff7c6d11 | 589 | discr: Operand::Move(discr), |
cc61c64b | 590 | switch_ty: discr_ty, |
29967ef6 XL |
591 | targets: SwitchTargets::new( |
592 | values.iter().copied().zip(blocks.iter().copied()), | |
593 | *blocks.last().unwrap(), | |
594 | ), | |
dfeec247 | 595 | }, |
cc61c64b | 596 | }), |
7cac9316 XL |
597 | is_cleanup: unwind.is_cleanup(), |
598 | }; | |
599 | let switch_block = self.elaborator.patch().new_block(switch_block); | |
600 | self.drop_flag_test_block(switch_block, succ, unwind) | |
cc61c64b XL |
601 | } |
602 | ||
dc9dc135 | 603 | fn destructor_call_block(&mut self, (succ, unwind): (BasicBlock, Unwind)) -> BasicBlock { |
cc61c64b XL |
604 | debug!("destructor_call_block({:?}, {:?})", self, succ); |
605 | let tcx = self.tcx(); | |
3dfed10e | 606 | let drop_trait = tcx.require_lang_item(LangItem::Drop, None); |
74b04a01 | 607 | let drop_fn = tcx.associated_items(drop_trait).in_definition_order().next().unwrap(); |
ff7c6d11 | 608 | let ty = self.place_ty(self.place); |
94b46f34 | 609 | let substs = tcx.mk_substs_trait(ty, &[]); |
cc61c64b | 610 | |
dfeec247 XL |
611 | let ref_ty = |
612 | tcx.mk_ref(tcx.lifetimes.re_erased, ty::TypeAndMut { ty, mutbl: hir::Mutability::Mut }); | |
ff7c6d11 | 613 | let ref_place = self.new_temp(ref_ty); |
dc9dc135 | 614 | let unit_temp = Place::from(self.new_temp(tcx.mk_unit())); |
cc61c64b | 615 | |
7cac9316 XL |
616 | let result = BasicBlockData { |
617 | statements: vec![self.assign( | |
ba9703b0 | 618 | Place::from(ref_place), |
dfeec247 XL |
619 | Rvalue::Ref( |
620 | tcx.lifetimes.re_erased, | |
621 | BorrowKind::Mut { allow_two_phase_borrow: false }, | |
ba9703b0 | 622 | self.place, |
dfeec247 | 623 | ), |
7cac9316 | 624 | )], |
cc61c64b XL |
625 | terminator: Some(Terminator { |
626 | kind: TerminatorKind::Call { | |
dfeec247 XL |
627 | func: Operand::function_handle( |
628 | tcx, | |
629 | drop_fn.def_id, | |
630 | substs, | |
631 | self.source_info.span, | |
632 | ), | |
dc9dc135 | 633 | args: vec![Operand::Move(Place::from(ref_place))], |
cc61c64b | 634 | destination: Some((unit_temp, succ)), |
7cac9316 | 635 | cleanup: unwind.into_option(), |
0bf4aa26 | 636 | from_hir_call: true, |
f035d41b | 637 | fn_span: self.source_info.span, |
cc61c64b | 638 | }, |
0bf4aa26 | 639 | source_info: self.source_info, |
cc61c64b | 640 | }), |
7cac9316 XL |
641 | is_cleanup: unwind.is_cleanup(), |
642 | }; | |
643 | self.elaborator.patch().new_block(result) | |
644 | } | |
645 | ||
48663c56 | 646 | /// Create a loop that drops an array: |
7cac9316 | 647 | /// |
48663c56 | 648 | /// ```text |
7cac9316 XL |
649 | /// loop-block: |
650 | /// can_go = cur == length_or_end | |
651 | /// if can_go then succ else drop-block | |
652 | /// drop-block: | |
653 | /// if ptr_based { | |
dfeec247 | 654 | /// ptr = cur |
7cac9316 XL |
655 | /// cur = cur.offset(1) |
656 | /// } else { | |
dfeec247 | 657 | /// ptr = &raw mut P[cur] |
7cac9316 XL |
658 | /// cur = cur + 1 |
659 | /// } | |
660 | /// drop(ptr) | |
48663c56 XL |
661 | /// ``` |
662 | fn drop_loop( | |
663 | &mut self, | |
664 | succ: BasicBlock, | |
665 | cur: Local, | |
ba9703b0 | 666 | length_or_end: Place<'tcx>, |
48663c56 XL |
667 | ety: Ty<'tcx>, |
668 | unwind: Unwind, | |
669 | ptr_based: bool, | |
670 | ) -> BasicBlock { | |
dfeec247 XL |
671 | let copy = |place: Place<'tcx>| Operand::Copy(place); |
672 | let move_ = |place: Place<'tcx>| Operand::Move(place); | |
7cac9316 XL |
673 | let tcx = self.tcx(); |
674 | ||
dfeec247 | 675 | let ptr_ty = tcx.mk_ptr(ty::TypeAndMut { ty: ety, mutbl: hir::Mutability::Mut }); |
ba9703b0 | 676 | let ptr = Place::from(self.new_temp(ptr_ty)); |
dfeec247 | 677 | let can_go = Place::from(self.new_temp(tcx.types.bool)); |
7cac9316 XL |
678 | |
679 | let one = self.constant_usize(1); | |
680 | let (ptr_next, cur_next) = if ptr_based { | |
6a06907d XL |
681 | ( |
682 | Rvalue::Use(copy(cur.into())), | |
94222f64 | 683 | Rvalue::BinaryOp(BinOp::Offset, Box::new((move_(cur.into()), one))), |
6a06907d | 684 | ) |
7cac9316 | 685 | } else { |
dfeec247 | 686 | ( |
ba9703b0 | 687 | Rvalue::AddressOf(Mutability::Mut, tcx.mk_place_index(self.place, cur)), |
94222f64 | 688 | Rvalue::BinaryOp(BinOp::Add, Box::new((move_(cur.into()), one))), |
dfeec247 | 689 | ) |
7cac9316 XL |
690 | }; |
691 | ||
692 | let drop_block = BasicBlockData { | |
ba9703b0 | 693 | statements: vec![self.assign(ptr, ptr_next), self.assign(Place::from(cur), cur_next)], |
7cac9316 XL |
694 | is_cleanup: unwind.is_cleanup(), |
695 | terminator: Some(Terminator { | |
696 | source_info: self.source_info, | |
697 | // this gets overwritten by drop elaboration. | |
698 | kind: TerminatorKind::Unreachable, | |
dfeec247 | 699 | }), |
7cac9316 XL |
700 | }; |
701 | let drop_block = self.elaborator.patch().new_block(drop_block); | |
702 | ||
703 | let loop_block = BasicBlockData { | |
dfeec247 | 704 | statements: vec![self.assign( |
ba9703b0 | 705 | can_go, |
94222f64 XL |
706 | Rvalue::BinaryOp( |
707 | BinOp::Eq, | |
708 | Box::new((copy(Place::from(cur)), copy(length_or_end))), | |
709 | ), | |
dfeec247 | 710 | )], |
7cac9316 XL |
711 | is_cleanup: unwind.is_cleanup(), |
712 | terminator: Some(Terminator { | |
713 | source_info: self.source_info, | |
dfeec247 XL |
714 | kind: TerminatorKind::if_(tcx, move_(can_go), succ, drop_block), |
715 | }), | |
7cac9316 XL |
716 | }; |
717 | let loop_block = self.elaborator.patch().new_block(loop_block); | |
718 | ||
dfeec247 XL |
719 | self.elaborator.patch().patch_terminator( |
720 | drop_block, | |
721 | TerminatorKind::Drop { | |
f035d41b | 722 | place: tcx.mk_place_deref(ptr), |
dfeec247 XL |
723 | target: loop_block, |
724 | unwind: unwind.into_option(), | |
725 | }, | |
726 | ); | |
7cac9316 XL |
727 | |
728 | loop_block | |
729 | } | |
730 | ||
ff7c6d11 XL |
731 | fn open_drop_for_array(&mut self, ety: Ty<'tcx>, opt_size: Option<u64>) -> BasicBlock { |
732 | debug!("open_drop_for_array({:?}, {:?})", ety, opt_size); | |
7cac9316 XL |
733 | |
734 | // if size_of::<ety>() == 0 { | |
735 | // index_based_loop | |
736 | // } else { | |
737 | // ptr_based_loop | |
738 | // } | |
739 | ||
e74abb32 XL |
740 | let tcx = self.tcx(); |
741 | ||
ff7c6d11 | 742 | if let Some(size) = opt_size { |
e74abb32 XL |
743 | let fields: Vec<(Place<'tcx>, Option<D::Path>)> = (0..size) |
744 | .map(|i| { | |
745 | ( | |
746 | tcx.mk_place_elem( | |
ba9703b0 | 747 | self.place, |
e74abb32 XL |
748 | ProjectionElem::ConstantIndex { |
749 | offset: i, | |
750 | min_length: size, | |
751 | from_end: false, | |
752 | }, | |
753 | ), | |
754 | self.elaborator.array_subpath(self.path, i, size), | |
755 | ) | |
756 | }) | |
757 | .collect(); | |
ff7c6d11 | 758 | |
dfeec247 | 759 | if fields.iter().any(|(_, path)| path.is_some()) { |
ff7c6d11 | 760 | let (succ, unwind) = self.drop_ladder_bottom(); |
dfeec247 | 761 | return self.drop_ladder(fields, succ, unwind).0; |
ff7c6d11 XL |
762 | } |
763 | } | |
7cac9316 | 764 | |
ba9703b0 XL |
765 | let move_ = |place: Place<'tcx>| Operand::Move(place); |
766 | let elem_size = Place::from(self.new_temp(tcx.types.usize)); | |
767 | let len = Place::from(self.new_temp(tcx.types.usize)); | |
48663c56 | 768 | |
7cac9316 XL |
769 | let base_block = BasicBlockData { |
770 | statements: vec![ | |
48663c56 | 771 | self.assign(elem_size, Rvalue::NullaryOp(NullOp::SizeOf, ety)), |
ba9703b0 | 772 | self.assign(len, Rvalue::Len(self.place)), |
7cac9316 XL |
773 | ], |
774 | is_cleanup: self.unwind.is_cleanup(), | |
775 | terminator: Some(Terminator { | |
776 | source_info: self.source_info, | |
48663c56 XL |
777 | kind: TerminatorKind::SwitchInt { |
778 | discr: move_(elem_size), | |
779 | switch_ty: tcx.types.usize, | |
29967ef6 XL |
780 | targets: SwitchTargets::static_if( |
781 | 0, | |
ba9703b0 XL |
782 | self.drop_loop_pair(ety, false, len), |
783 | self.drop_loop_pair(ety, true, len), | |
29967ef6 | 784 | ), |
48663c56 | 785 | }, |
dfeec247 | 786 | }), |
7cac9316 XL |
787 | }; |
788 | self.elaborator.patch().new_block(base_block) | |
789 | } | |
790 | ||
74b04a01 | 791 | /// Creates a pair of drop-loops of `place`, which drops its contents, even |
48663c56 XL |
792 | /// in the case of 1 panic. If `ptr_based`, creates a pointer loop, |
793 | /// otherwise create an index loop. | |
794 | fn drop_loop_pair( | |
795 | &mut self, | |
796 | ety: Ty<'tcx>, | |
797 | ptr_based: bool, | |
798 | length: Place<'tcx>, | |
799 | ) -> BasicBlock { | |
7cac9316 XL |
800 | debug!("drop_loop_pair({:?}, {:?})", ety, ptr_based); |
801 | let tcx = self.tcx(); | |
dfeec247 | 802 | let iter_ty = if ptr_based { tcx.mk_mut_ptr(ety) } else { tcx.types.usize }; |
7cac9316 | 803 | |
ea8adc8c | 804 | let cur = self.new_temp(iter_ty); |
dfeec247 | 805 | let length_or_end = if ptr_based { Place::from(self.new_temp(iter_ty)) } else { length }; |
7cac9316 XL |
806 | |
807 | let unwind = self.unwind.map(|unwind| { | |
ba9703b0 | 808 | self.drop_loop(unwind, cur, length_or_end, ety, Unwind::InCleanup, ptr_based) |
7cac9316 XL |
809 | }); |
810 | ||
ba9703b0 | 811 | let loop_block = self.drop_loop(self.succ, cur, length_or_end, ety, unwind, ptr_based); |
7cac9316 | 812 | |
dc9dc135 | 813 | let cur = Place::from(cur); |
48663c56 | 814 | let drop_block_stmts = if ptr_based { |
ff7c6d11 | 815 | let tmp_ty = tcx.mk_mut_ptr(self.place_ty(self.place)); |
dc9dc135 | 816 | let tmp = Place::from(self.new_temp(tmp_ty)); |
dfeec247 | 817 | // tmp = &raw mut P; |
7cac9316 XL |
818 | // cur = tmp as *mut T; |
819 | // end = Offset(cur, len); | |
48663c56 | 820 | vec![ |
ba9703b0 XL |
821 | self.assign(tmp, Rvalue::AddressOf(Mutability::Mut, self.place)), |
822 | self.assign(cur, Rvalue::Cast(CastKind::Misc, Operand::Move(tmp), iter_ty)), | |
48663c56 | 823 | self.assign( |
ba9703b0 | 824 | length_or_end, |
6a06907d XL |
825 | Rvalue::BinaryOp( |
826 | BinOp::Offset, | |
94222f64 | 827 | Box::new((Operand::Copy(cur), Operand::Move(length))), |
6a06907d | 828 | ), |
dfeec247 | 829 | ), |
48663c56 | 830 | ] |
7cac9316 | 831 | } else { |
48663c56 XL |
832 | // cur = 0 (length already pushed) |
833 | let zero = self.constant_usize(0); | |
ba9703b0 | 834 | vec![self.assign(cur, Rvalue::Use(zero))] |
48663c56 | 835 | }; |
7cac9316 XL |
836 | let drop_block = self.elaborator.patch().new_block(BasicBlockData { |
837 | statements: drop_block_stmts, | |
838 | is_cleanup: unwind.is_cleanup(), | |
839 | terminator: Some(Terminator { | |
840 | source_info: self.source_info, | |
dfeec247 XL |
841 | kind: TerminatorKind::Goto { target: loop_block }, |
842 | }), | |
7cac9316 XL |
843 | }); |
844 | ||
845 | // FIXME(#34708): handle partially-dropped array/slice elements. | |
846 | let reset_block = self.drop_flag_reset_block(DropFlagMode::Deep, drop_block, unwind); | |
48663c56 | 847 | self.drop_flag_test_block(reset_block, self.succ, unwind) |
cc61c64b XL |
848 | } |
849 | ||
850 | /// The slow-path - create an "open", elaborated drop for a type | |
851 | /// which is moved-out-of only partially, and patch `bb` to a jump | |
852 | /// to it. This must not be called on ADTs with a destructor, | |
853 | /// as these can't be moved-out-of, except for `Box<T>`, which is | |
854 | /// special-cased. | |
855 | /// | |
856 | /// This creates a "drop ladder" that drops the needed fields of the | |
857 | /// ADT, both in the success case or if one of the destructors fail. | |
dc9dc135 | 858 | fn open_drop(&mut self) -> BasicBlock { |
ff7c6d11 | 859 | let ty = self.place_ty(self.place); |
1b1a35ee | 860 | match ty.kind() { |
ba9703b0 XL |
861 | ty::Closure(_, substs) => { |
862 | let tys: Vec<_> = substs.as_closure().upvar_tys().collect(); | |
94b46f34 XL |
863 | self.open_drop_for_tuple(&tys) |
864 | } | |
ea8adc8c XL |
865 | // Note that `elaborate_drops` only drops the upvars of a generator, |
866 | // and this is ok because `open_drop` here can only be reached | |
867 | // within that own generator's resume function. | |
868 | // This should only happen for the self argument on the resume function. | |
869 | // It effetively only contains upvars until the generator transformation runs. | |
dc9dc135 | 870 | // See librustc_body/transform/generator.rs for more details. |
ba9703b0 XL |
871 | ty::Generator(_, substs, _) => { |
872 | let tys: Vec<_> = substs.as_generator().upvar_tys().collect(); | |
cc61c64b XL |
873 | self.open_drop_for_tuple(&tys) |
874 | } | |
416331ca XL |
875 | ty::Tuple(..) => { |
876 | let tys: Vec<_> = ty.tuple_fields().collect(); | |
48663c56 | 877 | self.open_drop_for_tuple(&tys) |
cc61c64b | 878 | } |
b7449926 | 879 | ty::Adt(def, substs) => { |
83c7162d XL |
880 | if def.is_box() { |
881 | self.open_drop_for_box(def, substs) | |
882 | } else { | |
883 | self.open_drop_for_adt(def, substs) | |
884 | } | |
cc61c64b | 885 | } |
29967ef6 | 886 | ty::Dynamic(..) => self.complete_drop(self.succ, self.unwind), |
b7449926 | 887 | ty::Array(ety, size) => { |
416331ca | 888 | let size = size.try_eval_usize(self.tcx(), self.elaborator.param_env()); |
94b46f34 | 889 | self.open_drop_for_array(ety, size) |
dfeec247 | 890 | } |
b7449926 | 891 | ty::Slice(ety) => self.open_drop_for_array(ety, None), |
ff7c6d11 | 892 | |
dfeec247 | 893 | _ => bug!("open drop from non-ADT `{:?}`", ty), |
cc61c64b XL |
894 | } |
895 | } | |
896 | ||
29967ef6 XL |
897 | fn complete_drop(&mut self, succ: BasicBlock, unwind: Unwind) -> BasicBlock { |
898 | debug!("complete_drop(succ={:?}, unwind={:?})", succ, unwind); | |
cc61c64b | 899 | |
7cac9316 | 900 | let drop_block = self.drop_block(succ, unwind); |
7cac9316 XL |
901 | |
902 | self.drop_flag_test_block(drop_block, succ, unwind) | |
903 | } | |
cc61c64b | 904 | |
f9f354fc XL |
905 | /// Creates a block that resets the drop flag. If `mode` is deep, all children drop flags will |
906 | /// also be cleared. | |
dfeec247 XL |
907 | fn drop_flag_reset_block( |
908 | &mut self, | |
909 | mode: DropFlagMode, | |
910 | succ: BasicBlock, | |
911 | unwind: Unwind, | |
912 | ) -> BasicBlock { | |
7cac9316 XL |
913 | debug!("drop_flag_reset_block({:?},{:?})", self, mode); |
914 | ||
29967ef6 XL |
915 | if unwind.is_cleanup() { |
916 | // The drop flag isn't read again on the unwind path, so don't | |
917 | // bother setting it. | |
918 | return succ; | |
919 | } | |
7cac9316 | 920 | let block = self.new_block(unwind, TerminatorKind::Goto { target: succ }); |
74b04a01 | 921 | let block_start = Location { block, statement_index: 0 }; |
7cac9316 XL |
922 | self.elaborator.clear_drop_flag(block_start, self.path, mode); |
923 | block | |
cc61c64b XL |
924 | } |
925 | ||
dc9dc135 | 926 | fn elaborated_drop_block(&mut self) -> BasicBlock { |
cc61c64b | 927 | debug!("elaborated_drop_block({:?})", self); |
f9f354fc | 928 | let blk = self.drop_block(self.succ, self.unwind); |
cc61c64b XL |
929 | self.elaborate_drop(blk); |
930 | blk | |
931 | } | |
932 | ||
f9f354fc XL |
933 | /// Creates a block that frees the backing memory of a `Box` if its drop is required (either |
934 | /// statically or by checking its drop flag). | |
935 | /// | |
936 | /// The contained value will not be dropped. | |
dc9dc135 | 937 | fn box_free_block( |
cc61c64b | 938 | &mut self, |
83c7162d | 939 | adt: &'tcx ty::AdtDef, |
532ac7d7 | 940 | substs: SubstsRef<'tcx>, |
cc61c64b | 941 | target: BasicBlock, |
7cac9316 | 942 | unwind: Unwind, |
cc61c64b | 943 | ) -> BasicBlock { |
83c7162d | 944 | let block = self.unelaborated_free_block(adt, substs, target, unwind); |
7cac9316 | 945 | self.drop_flag_test_block(block, target, unwind) |
cc61c64b XL |
946 | } |
947 | ||
f9f354fc XL |
948 | /// Creates a block that frees the backing memory of a `Box` (without dropping the contained |
949 | /// value). | |
dc9dc135 | 950 | fn unelaborated_free_block( |
cc61c64b | 951 | &mut self, |
83c7162d | 952 | adt: &'tcx ty::AdtDef, |
532ac7d7 | 953 | substs: SubstsRef<'tcx>, |
cc61c64b | 954 | target: BasicBlock, |
dc9dc135 | 955 | unwind: Unwind, |
cc61c64b XL |
956 | ) -> BasicBlock { |
957 | let tcx = self.tcx(); | |
dc9dc135 | 958 | let unit_temp = Place::from(self.new_temp(tcx.mk_unit())); |
3dfed10e | 959 | let free_func = tcx.require_lang_item(LangItem::BoxFree, Some(self.source_info.span)); |
dfeec247 XL |
960 | let args = adt.variants[VariantIdx::new(0)] |
961 | .fields | |
962 | .iter() | |
963 | .enumerate() | |
964 | .map(|(i, f)| { | |
965 | let field = Field::new(i); | |
966 | let field_ty = f.ty(tcx, substs); | |
ba9703b0 | 967 | Operand::Move(tcx.mk_place_field(self.place, field, field_ty)) |
dfeec247 XL |
968 | }) |
969 | .collect(); | |
cc61c64b XL |
970 | |
971 | let call = TerminatorKind::Call { | |
972 | func: Operand::function_handle(tcx, free_func, substs, self.source_info.span), | |
74b04a01 | 973 | args, |
cc61c64b | 974 | destination: Some((unit_temp, target)), |
0bf4aa26 XL |
975 | cleanup: None, |
976 | from_hir_call: false, | |
f035d41b | 977 | fn_span: self.source_info.span, |
0531ce1d | 978 | }; // FIXME(#43234) |
7cac9316 | 979 | let free_block = self.new_block(unwind, call); |
cc61c64b XL |
980 | |
981 | let block_start = Location { block: free_block, statement_index: 0 }; | |
982 | self.elaborator.clear_drop_flag(block_start, self.path, DropFlagMode::Shallow); | |
983 | free_block | |
984 | } | |
985 | ||
dc9dc135 | 986 | fn drop_block(&mut self, target: BasicBlock, unwind: Unwind) -> BasicBlock { |
dfeec247 | 987 | let block = |
f035d41b | 988 | TerminatorKind::Drop { place: self.place, target, unwind: unwind.into_option() }; |
7cac9316 | 989 | self.new_block(unwind, block) |
cc61c64b XL |
990 | } |
991 | ||
74b04a01 XL |
992 | fn goto_block(&mut self, target: BasicBlock, unwind: Unwind) -> BasicBlock { |
993 | let block = TerminatorKind::Goto { target }; | |
994 | self.new_block(unwind, block) | |
995 | } | |
996 | ||
f9f354fc XL |
997 | /// Returns the block to jump to in order to test the drop flag and execute the drop. |
998 | /// | |
999 | /// Depending on the required `DropStyle`, this might be a generated block with an `if` | |
1000 | /// terminator (for dynamic/open drops), or it might be `on_set` or `on_unset` itself, in case | |
1001 | /// the drop can be statically determined. | |
dfeec247 XL |
1002 | fn drop_flag_test_block( |
1003 | &mut self, | |
1004 | on_set: BasicBlock, | |
1005 | on_unset: BasicBlock, | |
1006 | unwind: Unwind, | |
1007 | ) -> BasicBlock { | |
cc61c64b | 1008 | let style = self.elaborator.drop_style(self.path, DropFlagMode::Shallow); |
dfeec247 XL |
1009 | debug!( |
1010 | "drop_flag_test_block({:?},{:?},{:?},{:?}) - {:?}", | |
1011 | self, on_set, on_unset, unwind, style | |
1012 | ); | |
cc61c64b XL |
1013 | |
1014 | match style { | |
1015 | DropStyle::Dead => on_unset, | |
1016 | DropStyle::Static => on_set, | |
1017 | DropStyle::Conditional | DropStyle::Open => { | |
1018 | let flag = self.elaborator.get_drop_flag(self.path).unwrap(); | |
1019 | let term = TerminatorKind::if_(self.tcx(), flag, on_set, on_unset); | |
7cac9316 | 1020 | self.new_block(unwind, term) |
cc61c64b XL |
1021 | } |
1022 | } | |
1023 | } | |
1024 | ||
dc9dc135 | 1025 | fn new_block(&mut self, unwind: Unwind, k: TerminatorKind<'tcx>) -> BasicBlock { |
cc61c64b XL |
1026 | self.elaborator.patch().new_block(BasicBlockData { |
1027 | statements: vec![], | |
dfeec247 XL |
1028 | terminator: Some(Terminator { source_info: self.source_info, kind: k }), |
1029 | is_cleanup: unwind.is_cleanup(), | |
cc61c64b XL |
1030 | }) |
1031 | } | |
1032 | ||
1033 | fn new_temp(&mut self, ty: Ty<'tcx>) -> Local { | |
1034 | self.elaborator.patch().new_temp(ty, self.source_info.span) | |
1035 | } | |
1036 | ||
7cac9316 | 1037 | fn constant_usize(&self, val: u16) -> Operand<'tcx> { |
94222f64 | 1038 | Operand::Constant(Box::new(Constant { |
7cac9316 | 1039 | span: self.source_info.span, |
b7449926 | 1040 | user_ty: None, |
6a06907d | 1041 | literal: ty::Const::from_usize(self.tcx(), val.into()).into(), |
94222f64 | 1042 | })) |
7cac9316 XL |
1043 | } |
1044 | ||
ba9703b0 | 1045 | fn assign(&self, lhs: Place<'tcx>, rhs: Rvalue<'tcx>) -> Statement<'tcx> { |
94222f64 XL |
1046 | Statement { |
1047 | source_info: self.source_info, | |
1048 | kind: StatementKind::Assign(Box::new((lhs, rhs))), | |
1049 | } | |
7cac9316 | 1050 | } |
cc61c64b | 1051 | } |