1 use crate::{shim, util}
;
2 use required_consts
::RequiredConstsVisitor
;
3 use rustc_data_structures
::fx
::FxHashSet
;
4 use rustc_data_structures
::steal
::Steal
;
6 use rustc_hir
::def_id
::{DefId, LocalDefId}
;
7 use rustc_hir
::intravisit
::{self, NestedVisitorMap, Visitor}
;
8 use rustc_index
::vec
::IndexVec
;
9 use rustc_middle
::mir
::visit
::Visitor
as _
;
10 use rustc_middle
::mir
::{traversal, Body, ConstQualifs, MirPhase, Promoted}
;
11 use rustc_middle
::ty
::query
::Providers
;
12 use rustc_middle
::ty
::{self, TyCtxt, TypeFoldable}
;
13 use rustc_span
::{Span, Symbol}
;
16 pub mod add_call_guards
;
17 pub mod add_moves_for_packed_drops
;
19 pub mod check_const_item_mutation
;
21 pub mod check_packed_ref
;
22 pub mod check_unsafety
;
23 pub mod cleanup_post_borrowck
;
24 pub mod const_debuginfo
;
29 pub mod deduplicate_blocks
;
32 pub mod early_otherwise_branch
;
33 pub mod elaborate_drops
;
34 pub mod function_item_references
;
38 pub mod lower_intrinsics
;
39 pub mod match_branches
;
40 pub mod multiple_return_terminators
;
41 pub mod no_landing_pads
;
43 pub mod promote_consts
;
44 pub mod remove_noop_landing_pads
;
45 pub mod remove_storage_markers
;
46 pub mod remove_unneeded_drops
;
48 pub mod required_consts
;
51 pub mod simplify_branches
;
52 pub mod simplify_comparison_integral
;
54 pub mod uninhabited_enum_branching
;
55 pub mod unreachable_prop
;
58 pub use rustc_middle
::mir
::MirSource
;
60 pub(crate) fn provide(providers
: &mut Providers
) {
61 self::check_unsafety
::provide(providers
);
62 self::check_packed_ref
::provide(providers
);
63 *providers
= Providers
{
66 mir_const_qualif
: |tcx
, def_id
| {
67 let def_id
= def_id
.expect_local();
68 if let Some(def
) = ty
::WithOptConstParam
::try_lookup(def_id
, tcx
) {
69 tcx
.mir_const_qualif_const_arg(def
)
71 mir_const_qualif(tcx
, ty
::WithOptConstParam
::unknown(def_id
))
74 mir_const_qualif_const_arg
: |tcx
, (did
, param_did
)| {
75 mir_const_qualif(tcx
, ty
::WithOptConstParam { did, const_param_did: Some(param_did) }
)
78 mir_drops_elaborated_and_const_checked
,
80 mir_for_ctfe_of_const_arg
,
83 is_ctfe_mir_available
: |tcx
, did
| is_mir_available(tcx
, did
),
84 promoted_mir
: |tcx
, def_id
| {
85 let def_id
= def_id
.expect_local();
86 if let Some(def
) = ty
::WithOptConstParam
::try_lookup(def_id
, tcx
) {
87 tcx
.promoted_mir_of_const_arg(def
)
89 promoted_mir(tcx
, ty
::WithOptConstParam
::unknown(def_id
))
92 promoted_mir_of_const_arg
: |tcx
, (did
, param_did
)| {
93 promoted_mir(tcx
, ty
::WithOptConstParam { did, const_param_did: Some(param_did) }
)
97 coverage
::query
::provide(providers
);
100 fn is_mir_available(tcx
: TyCtxt
<'_
>, def_id
: DefId
) -> bool
{
101 let def_id
= def_id
.expect_local();
102 tcx
.mir_keys(()).contains(&def_id
)
105 /// Finds the full set of `DefId`s within the current crate that have
106 /// MIR associated with them.
107 fn mir_keys(tcx
: TyCtxt
<'_
>, (): ()) -> FxHashSet
<LocalDefId
> {
108 let mut set
= FxHashSet
::default();
110 // All body-owners have MIR associated with them.
111 set
.extend(tcx
.body_owners());
113 // Additionally, tuple struct/variant constructors have MIR, but
114 // they don't have a BodyId, so we need to build them separately.
115 struct GatherCtors
<'a
, 'tcx
> {
117 set
: &'a
mut FxHashSet
<LocalDefId
>,
119 impl<'a
, 'tcx
> Visitor
<'tcx
> for GatherCtors
<'a
, 'tcx
> {
120 fn visit_variant_data(
122 v
: &'tcx hir
::VariantData
<'tcx
>,
124 _
: &'tcx hir
::Generics
<'tcx
>,
128 if let hir
::VariantData
::Tuple(_
, hir_id
) = *v
{
129 self.set
.insert(self.tcx
.hir().local_def_id(hir_id
));
131 intravisit
::walk_struct_def(self, v
)
133 type Map
= intravisit
::ErasedMap
<'tcx
>;
134 fn nested_visit_map(&mut self) -> NestedVisitorMap
<Self::Map
> {
135 NestedVisitorMap
::None
140 .visit_all_item_likes(&mut GatherCtors { tcx, set: &mut set }
.as_deep_visitor());
145 /// Generates a default name for the pass based on the name of the
147 pub fn default_name
<T
: ?Sized
>() -> Cow
<'
static, str> {
148 let name
= std
::any
::type_name
::<T
>();
149 if let Some(tail
) = name
.rfind('
:'
) { Cow::from(&name[tail + 1..]) }
else { Cow::from(name) }
152 /// A streamlined trait that you can implement to create a pass; the
153 /// pass will be named after the type, and it will consist of a main
154 /// loop that goes over each available MIR and applies `run_pass`.
155 pub trait MirPass
<'tcx
> {
156 fn name(&self) -> Cow
<'_
, str> {
157 default_name
::<Self>()
160 fn run_pass(&self, tcx
: TyCtxt
<'tcx
>, body
: &mut Body
<'tcx
>);
165 body
: &mut Body
<'tcx
>,
167 passes
: &[&[&dyn MirPass
<'tcx
>]],
169 let phase_index
= mir_phase
.phase_index();
170 let validate
= tcx
.sess
.opts
.debugging_opts
.validate_mir
;
172 if body
.phase
>= mir_phase
{
177 validate
::Validator { when: format!("input to phase {:?}
", mir_phase), mir_phase }
178 .run_pass(tcx, body);
182 let mut run_pass = |pass: &dyn MirPass<'tcx>| {
183 let run_hooks = |body: &_, index, is_after| {
184 dump_mir::on_mir_pass(
186 &format_args!("{:03}
-{:03}
", phase_index, index),
192 run_hooks(body, index, false);
193 pass.run_pass(tcx, body);
194 run_hooks(body, index, true);
197 validate::Validator {
198 when: format!("after {}
in phase {:?}
", pass.name(), mir_phase),
201 .run_pass(tcx, body);
207 for pass_group in passes {
208 for pass in *pass_group {
213 body.phase = mir_phase;
215 if mir_phase == MirPhase::Optimization {
216 validate::Validator { when: format!("end of phase {:?}", mir_phase
), mir_phase
}
217 .run_pass(tcx
, body
);
221 fn mir_const_qualif(tcx
: TyCtxt
<'_
>, def
: ty
::WithOptConstParam
<LocalDefId
>) -> ConstQualifs
{
222 let const_kind
= tcx
.hir().body_const_context(def
.did
);
224 // No need to const-check a non-const `fn`.
225 if const_kind
.is_none() {
226 return Default
::default();
229 // N.B., this `borrow()` is guaranteed to be valid (i.e., the value
230 // cannot yet be stolen), because `mir_promoted()`, which steals
231 // from `mir_const(), forces this query to execute before
232 // performing the steal.
233 let body
= &tcx
.mir_const(def
).borrow();
235 if body
.return_ty().references_error() {
236 tcx
.sess
.delay_span_bug(body
.span
, "mir_const_qualif: MIR had errors");
237 return Default
::default();
240 let ccx
= check_consts
::ConstCx { body, tcx, const_kind, param_env: tcx.param_env(def.did) }
;
242 let mut validator
= check_consts
::validation
::Validator
::new(&ccx
);
243 validator
.check_body();
245 // We return the qualifs in the return place for every MIR body, even though it is only used
246 // when deciding to promote a reference to a `const` for now.
247 validator
.qualifs_in_return_place()
250 /// Make MIR ready for const evaluation. This is run on all MIR, not just on consts!
253 def
: ty
::WithOptConstParam
<LocalDefId
>,
254 ) -> &'tcx Steal
<Body
<'tcx
>> {
255 if let Some(def
) = def
.try_upgrade(tcx
) {
256 return tcx
.mir_const(def
);
259 // Unsafety check uses the raw mir, so make sure it is run.
260 if let Some(param_did
) = def
.const_param_did
{
261 tcx
.ensure().unsafety_check_result_for_const_arg((def
.did
, param_did
));
263 tcx
.ensure().unsafety_check_result(def
.did
);
266 let mut body
= tcx
.mir_built(def
).steal();
268 util
::dump_mir(tcx
, None
, "mir_map", &0, &body
, |_
, _
| Ok(()));
276 &check_packed_ref
::CheckPackedRef
,
277 &check_const_item_mutation
::CheckConstItemMutation
,
278 &function_item_references
::FunctionItemReferences
,
279 // What we need to do constant evaluation.
280 &simplify
::SimplifyCfg
::new("initial"),
281 &rustc_peek
::SanityCheck
,
284 tcx
.alloc_steal_mir(body
)
287 /// Compute the main MIR body and the list of MIR bodies of the promoteds.
290 def
: ty
::WithOptConstParam
<LocalDefId
>,
291 ) -> (&'tcx Steal
<Body
<'tcx
>>, &'tcx Steal
<IndexVec
<Promoted
, Body
<'tcx
>>>) {
292 if let Some(def
) = def
.try_upgrade(tcx
) {
293 return tcx
.mir_promoted(def
);
296 // Ensure that we compute the `mir_const_qualif` for constants at
297 // this point, before we steal the mir-const result.
298 // Also this means promotion can rely on all const checks having been done.
299 let _
= tcx
.mir_const_qualif_opt_const_arg(def
);
300 let _
= tcx
.mir_abstract_const_opt_const_arg(def
.to_global());
301 let mut body
= tcx
.mir_const(def
).steal();
303 let mut required_consts
= Vec
::new();
304 let mut required_consts_visitor
= RequiredConstsVisitor
::new(&mut required_consts
);
305 for (bb
, bb_data
) in traversal
::reverse_postorder(&body
) {
306 required_consts_visitor
.visit_basic_block_data(bb
, bb_data
);
308 body
.required_consts
= required_consts
;
310 let promote_pass
= promote_consts
::PromoteTemps
::default();
311 let promote
: &[&dyn MirPass
<'tcx
>] = &[
312 // What we need to run borrowck etc.
314 &simplify
::SimplifyCfg
::new("promote-consts"),
317 let opt_coverage
: &[&dyn MirPass
<'tcx
>] =
318 if tcx
.sess
.instrument_coverage() { &[&coverage::InstrumentCoverage] }
else { &[] }
;
320 run_passes(tcx
, &mut body
, MirPhase
::ConstPromotion
, &[promote
, opt_coverage
]);
322 let promoted
= promote_pass
.promoted_fragments
.into_inner();
323 (tcx
.alloc_steal_mir(body
), tcx
.alloc_steal_promoted(promoted
))
326 /// Compute the MIR that is used during CTFE (and thus has no optimizations run on it)
327 fn mir_for_ctfe
<'tcx
>(tcx
: TyCtxt
<'tcx
>, def_id
: DefId
) -> &'tcx Body
<'tcx
> {
328 let did
= def_id
.expect_local();
329 if let Some(def
) = ty
::WithOptConstParam
::try_lookup(did
, tcx
) {
330 tcx
.mir_for_ctfe_of_const_arg(def
)
332 tcx
.arena
.alloc(inner_mir_for_ctfe(tcx
, ty
::WithOptConstParam
::unknown(did
)))
336 /// Same as `mir_for_ctfe`, but used to get the MIR of a const generic parameter.
337 /// The docs on `WithOptConstParam` explain this a bit more, but the TLDR is that
338 /// we'd get cycle errors with `mir_for_ctfe`, because typeck would need to typeck
339 /// the const parameter while type checking the main body, which in turn would try
340 /// to type check the main body again.
341 fn mir_for_ctfe_of_const_arg
<'tcx
>(
343 (did
, param_did
): (LocalDefId
, DefId
),
344 ) -> &'tcx Body
<'tcx
> {
345 tcx
.arena
.alloc(inner_mir_for_ctfe(
347 ty
::WithOptConstParam { did, const_param_did: Some(param_did) }
,
351 fn inner_mir_for_ctfe(tcx
: TyCtxt
<'_
>, def
: ty
::WithOptConstParam
<LocalDefId
>) -> Body
<'_
> {
352 // FIXME: don't duplicate this between the optimized_mir/mir_for_ctfe queries
353 if tcx
.is_constructor(def
.did
.to_def_id()) {
354 // There's no reason to run all of the MIR passes on constructors when
355 // we can just output the MIR we want directly. This also saves const
356 // qualification and borrow checking the trouble of special casing
358 return shim
::build_adt_ctor(tcx
, def
.did
.to_def_id());
363 .body_const_context(def
.did
)
364 .expect("mir_for_ctfe should not be used for runtime functions");
366 let mut body
= tcx
.mir_drops_elaborated_and_const_checked(def
).borrow().clone();
369 // Do not const prop functions, either they get executed at runtime or exported to metadata,
370 // so we run const prop on them, or they don't, in which case we const evaluate some control
371 // flow paths of the function and any errors in those paths will get emitted as const eval
373 hir
::ConstContext
::ConstFn
=> {}
374 // Static items always get evaluated, so we can just let const eval see if any erroneous
375 // control flow paths get executed.
376 hir
::ConstContext
::Static(_
) => {}
377 // Associated constants get const prop run so we detect common failure situations in the
378 // crate that defined the constant.
379 // Technically we want to not run on regular const items, but oli-obk doesn't know how to
380 // conveniently detect that at this point without looking at the HIR.
381 hir
::ConstContext
::Const
=> {
383 let optimizations
: &[&dyn MirPass
<'_
>] = &[
384 &const_prop
::ConstProp
,
391 MirPhase
::Optimization
,
399 debug_assert
!(!body
.has_free_regions(), "Free regions in MIR for CTFE");
404 /// Obtain just the main MIR (no promoteds) and run some cleanups on it. This also runs
405 /// mir borrowck *before* doing so in order to ensure that borrowck can be run and doesn't
406 /// end up missing the source MIR due to stealing happening.
407 fn mir_drops_elaborated_and_const_checked
<'tcx
>(
409 def
: ty
::WithOptConstParam
<LocalDefId
>,
410 ) -> &'tcx Steal
<Body
<'tcx
>> {
411 if let Some(def
) = def
.try_upgrade(tcx
) {
412 return tcx
.mir_drops_elaborated_and_const_checked(def
);
415 // (Mir-)Borrowck uses `mir_promoted`, so we have to force it to
416 // execute before we can steal.
417 if let Some(param_did
) = def
.const_param_did
{
418 tcx
.ensure().mir_borrowck_const_arg((def
.did
, param_did
));
420 tcx
.ensure().mir_borrowck(def
.did
);
423 let hir_id
= tcx
.hir().local_def_id_to_hir_id(def
.did
);
424 use rustc_middle
::hir
::map
::blocks
::FnLikeNode
;
425 let is_fn_like
= FnLikeNode
::from_node(tcx
.hir().get(hir_id
)).is_some();
427 let did
= def
.did
.to_def_id();
428 let def
= ty
::WithOptConstParam
::unknown(did
);
430 // Do not compute the mir call graph without said call graph actually being used.
431 if inline
::is_enabled(tcx
) {
432 let _
= tcx
.mir_inliner_callees(ty
::InstanceDef
::Item(def
));
436 let (body
, _
) = tcx
.mir_promoted(def
);
437 let mut body
= body
.steal();
439 run_post_borrowck_cleanup_passes(tcx
, &mut body
);
440 check_consts
::post_drop_elaboration
::check_live_drops(tcx
, &body
);
441 tcx
.alloc_steal_mir(body
)
444 /// After this series of passes, no lifetime analysis based on borrowing can be done.
445 fn run_post_borrowck_cleanup_passes
<'tcx
>(tcx
: TyCtxt
<'tcx
>, body
: &mut Body
<'tcx
>) {
446 debug
!("post_borrowck_cleanup({:?})", body
.source
.def_id());
448 let post_borrowck_cleanup
: &[&dyn MirPass
<'tcx
>] = &[
449 // Remove all things only needed by analysis
450 &no_landing_pads
::NoLandingPads
,
451 &simplify_branches
::SimplifyBranches
::new("initial"),
452 &remove_noop_landing_pads
::RemoveNoopLandingPads
,
453 &cleanup_post_borrowck
::CleanupNonCodegenStatements
,
454 &simplify
::SimplifyCfg
::new("early-opt"),
455 // These next passes must be executed together
456 &add_call_guards
::CriticalCallEdges
,
457 &elaborate_drops
::ElaborateDrops
,
458 &no_landing_pads
::NoLandingPads
,
459 // AddMovesForPackedDrops needs to run after drop
461 &add_moves_for_packed_drops
::AddMovesForPackedDrops
,
462 // `AddRetag` needs to run after `ElaborateDrops`. Otherwise it should run fairly late,
463 // but before optimizations begin.
464 &add_retag
::AddRetag
,
465 &lower_intrinsics
::LowerIntrinsics
,
466 &simplify
::SimplifyCfg
::new("elaborate-drops"),
467 // `Deaggregator` is conceptually part of MIR building, some backends rely on it happening
468 // and it can help optimizations.
469 &deaggregator
::Deaggregator
,
472 run_passes(tcx
, body
, MirPhase
::DropLowering
, &[post_borrowck_cleanup
]);
475 fn run_optimization_passes
<'tcx
>(tcx
: TyCtxt
<'tcx
>, body
: &mut Body
<'tcx
>) {
476 let mir_opt_level
= tcx
.sess
.mir_opt_level();
478 // Lowering generator control-flow and variables has to happen before we do anything else
479 // to them. We run some optimizations before that, because they may be harder to do on the state
480 // machine than on MIR with async primitives.
481 let optimizations_with_generators
: &[&dyn MirPass
<'tcx
>] = &[
482 &unreachable_prop
::UnreachablePropagation
,
483 &uninhabited_enum_branching
::UninhabitedEnumBranching
,
484 &simplify
::SimplifyCfg
::new("after-uninhabited-enum-branching"),
486 &generator
::StateTransform
,
489 // Even if we don't do optimizations, we still have to lower generators for codegen.
490 let no_optimizations_with_generators
: &[&dyn MirPass
<'tcx
>] = &[&generator
::StateTransform
];
492 // The main optimizations that we do on MIR.
493 let optimizations
: &[&dyn MirPass
<'tcx
>] = &[
494 &remove_storage_markers
::RemoveStorageMarkers
,
495 &remove_zsts
::RemoveZsts
,
496 &const_goto
::ConstGoto
,
497 &remove_unneeded_drops
::RemoveUnneededDrops
,
498 &match_branches
::MatchBranchSimplification
,
499 // inst combine is after MatchBranchSimplification to clean up Ne(_1, false)
500 &multiple_return_terminators
::MultipleReturnTerminators
,
501 &instcombine
::InstCombine
,
502 &const_prop
::ConstProp
,
503 &simplify_branches
::SimplifyBranches
::new("after-const-prop"),
504 &early_otherwise_branch
::EarlyOtherwiseBranch
,
505 &simplify_comparison_integral
::SimplifyComparisonIntegral
,
506 &simplify_try
::SimplifyArmIdentity
,
507 &simplify_try
::SimplifyBranchSame
,
508 &dest_prop
::DestinationPropagation
,
509 &simplify_branches
::SimplifyBranches
::new("final"),
510 &remove_noop_landing_pads
::RemoveNoopLandingPads
,
511 &simplify
::SimplifyCfg
::new("final"),
512 &nrvo
::RenameReturnPlace
,
513 &const_debuginfo
::ConstDebugInfo
,
514 &simplify
::SimplifyLocals
,
515 &multiple_return_terminators
::MultipleReturnTerminators
,
516 &deduplicate_blocks
::DeduplicateBlocks
,
519 // Optimizations to run even if mir optimizations have been disabled.
520 let no_optimizations
: &[&dyn MirPass
<'tcx
>] = &[
521 // FIXME(#70073): This pass is responsible for both optimization as well as some lints.
522 &const_prop
::ConstProp
,
525 // Some cleanup necessary at least for LLVM and potentially other codegen backends.
526 let pre_codegen_cleanup
: &[&dyn MirPass
<'tcx
>] = &[
527 &add_call_guards
::CriticalCallEdges
,
528 // Dump the end result for testing and debugging purposes.
529 &dump_mir
::Marker("PreCodegen"),
532 // End of pass declarations, now actually run the passes.
533 // Generator Lowering
538 MirPhase
::GeneratorLowering
,
540 if mir_opt_level
> 0 {
541 optimizations_with_generators
543 no_optimizations_with_generators
548 // Main optimization passes
553 MirPhase
::Optimization
,
555 if mir_opt_level
> 0 { optimizations }
else { no_optimizations }
,
561 /// Optimize the MIR and prepare it for codegen.
562 fn optimized_mir
<'tcx
>(tcx
: TyCtxt
<'tcx
>, did
: DefId
) -> &'tcx Body
<'tcx
> {
563 let did
= did
.expect_local();
564 assert_eq
!(ty
::WithOptConstParam
::try_lookup(did
, tcx
), None
);
565 tcx
.arena
.alloc(inner_optimized_mir(tcx
, did
))
568 fn inner_optimized_mir(tcx
: TyCtxt
<'_
>, did
: LocalDefId
) -> Body
<'_
> {
569 if tcx
.is_constructor(did
.to_def_id()) {
570 // There's no reason to run all of the MIR passes on constructors when
571 // we can just output the MIR we want directly. This also saves const
572 // qualification and borrow checking the trouble of special casing
574 return shim
::build_adt_ctor(tcx
, did
.to_def_id());
577 match tcx
.hir().body_const_context(did
) {
578 // Run the `mir_for_ctfe` query, which depends on `mir_drops_elaborated_and_const_checked`
579 // which we are going to steal below. Thus we need to run `mir_for_ctfe` first, so it
580 // computes and caches its result.
581 Some(hir
::ConstContext
::ConstFn
) => tcx
.ensure().mir_for_ctfe(did
),
583 Some(other
) => panic
!("do not use `optimized_mir` for constants: {:?}", other
),
586 tcx
.mir_drops_elaborated_and_const_checked(ty
::WithOptConstParam
::unknown(did
)).steal();
587 run_optimization_passes(tcx
, &mut body
);
589 debug_assert
!(!body
.has_free_regions(), "Free regions in optimized MIR");
594 /// Fetch all the promoteds of an item and prepare their MIR bodies to be ready for
595 /// constant evaluation once all substitutions become known.
596 fn promoted_mir
<'tcx
>(
598 def
: ty
::WithOptConstParam
<LocalDefId
>,
599 ) -> &'tcx IndexVec
<Promoted
, Body
<'tcx
>> {
600 if tcx
.is_constructor(def
.did
.to_def_id()) {
601 return tcx
.arena
.alloc(IndexVec
::new());
604 if let Some(param_did
) = def
.const_param_did
{
605 tcx
.ensure().mir_borrowck_const_arg((def
.did
, param_did
));
607 tcx
.ensure().mir_borrowck(def
.did
);
609 let (_
, promoted
) = tcx
.mir_promoted(def
);
610 let mut promoted
= promoted
.steal();
612 for body
in &mut promoted
{
613 run_post_borrowck_cleanup_passes(tcx
, body
);
616 debug_assert
!(!promoted
.has_free_regions(), "Free regions in promoted MIR");
618 tcx
.arena
.alloc(promoted
)