1 #![allow(rustc::potential_query_instability)]
2 #![feature(box_patterns)]
3 #![feature(drain_filter)]
4 #![feature(let_chains)]
5 #![feature(map_try_insert)]
6 #![feature(min_specialization)]
7 #![feature(never_type)]
9 #![feature(option_get_or_insert_default)]
10 #![feature(trusted_step)]
11 #![feature(try_blocks)]
12 #![feature(yeet_expr)]
13 #![feature(if_let_guard)]
14 #![recursion_limit = "256"]
19 extern crate rustc_middle;
21 use required_consts::RequiredConstsVisitor;
22 use rustc_const_eval::util;
23 use rustc_data_structures::fx::FxIndexSet;
24 use rustc_data_structures::steal::Steal;
26 use rustc_hir::def_id::{DefId, LocalDefId};
27 use rustc_hir::intravisit::{self, Visitor};
28 use rustc_index::vec::IndexVec;
29 use rustc_middle::mir::visit::Visitor as _;
30 use rustc_middle::mir::{
31 traversal, AnalysisPhase, Body, ConstQualifs, Constant, LocalDecl, MirPass, MirPhase, Operand,
32 Place, ProjectionElem, Promoted, RuntimePhase, Rvalue, SourceInfo, Statement, StatementKind,
35 use rustc_middle::ty::query::Providers;
36 use rustc_middle::ty::{self, TyCtxt, TypeVisitable};
42 use pass_manager::{self as pm, Lint, MirLint, WithMinOptLevel};
44 mod abort_unwinding_calls;
46 mod add_moves_for_packed_drops;
48 mod check_const_item_mutation;
50 pub mod check_unsafety;
51 // This pass is public to allow external drivers to perform MIR cleanup
52 pub mod cleanup_post_borrowck;
58 mod dataflow_const_prop;
59 mod dead_store_elimination;
61 mod deduce_param_attrs;
62 mod deduplicate_blocks;
66 mod early_otherwise_branch;
67 mod elaborate_box_derefs;
70 mod function_item_references;
77 mod multiple_return_terminators;
78 mod normalize_array_len;
80 // This pass is public to allow external drivers to perform MIR cleanup
81 pub mod remove_false_edges;
82 mod remove_noop_landing_pads;
83 mod remove_storage_markers;
84 mod remove_uninit_drops;
85 mod remove_unneeded_drops;
89 mod separate_const_switch;
91 // This pass is public to allow external drivers to perform MIR cleanup
93 mod simplify_branches;
94 mod simplify_comparison_integral;
97 mod uninhabited_enum_branching;
100 use rustc_const_eval::transform::check_consts::{self, ConstCx};
101 use rustc_const_eval::transform::promote_consts;
102 use rustc_const_eval::transform::validate;
103 use rustc_mir_dataflow::rustc_peek;
105 pub fn provide(providers: &mut Providers) {
106 check_unsafety::provide(providers);
107 check_packed_ref::provide(providers);
108 coverage::query::provide(providers);
109 ffi_unwind_calls::provide(providers);
110 shim::provide(providers);
111 *providers = Providers {
114 mir_const_qualif: |tcx, def_id| {
115 let def_id = def_id.expect_local();
116 if let Some(def) = ty::WithOptConstParam::try_lookup(def_id, tcx) {
117 tcx.mir_const_qualif_const_arg(def)
119 mir_const_qualif(tcx, ty::WithOptConstParam::unknown(def_id))
122 mir_const_qualif_const_arg: |tcx, (did, param_did)| {
123 mir_const_qualif(tcx, ty::WithOptConstParam { did, const_param_did: Some(param_did) })
126 mir_drops_elaborated_and_const_checked,
128 mir_for_ctfe_of_const_arg,
131 is_ctfe_mir_available: |tcx, did| is_mir_available(tcx, did),
132 mir_callgraph_reachable: inline::cycle::mir_callgraph_reachable,
133 mir_inliner_callees: inline::cycle::mir_inliner_callees,
134 promoted_mir: |tcx, def_id| {
135 let def_id = def_id.expect_local();
136 if let Some(def) = ty::WithOptConstParam::try_lookup(def_id, tcx) {
137 tcx.promoted_mir_of_const_arg(def)
139 promoted_mir(tcx, ty::WithOptConstParam::unknown(def_id))
142 promoted_mir_of_const_arg: |tcx, (did, param_did)| {
143 promoted_mir(tcx, ty::WithOptConstParam { did, const_param_did: Some(param_did) })
145 deduced_param_attrs: deduce_param_attrs::deduced_param_attrs,
150 fn remap_mir_for_const_eval_select<'tcx>(
152 mut body: Body<'tcx>,
153 context: hir::Constness,
155 for bb in body.basic_blocks.as_mut().iter_mut() {
156 let terminator = bb.terminator.as_mut().expect("invalid terminator");
157 match terminator.kind {
158 TerminatorKind::Call {
159 func: Operand::Constant(box Constant { ref literal, .. }),
166 } if let ty::FnDef(def_id, _) = *literal.ty().kind()
167 && tcx.item_name(def_id) == sym::const_eval_select
168 && tcx.is_intrinsic(def_id) =>
170 let [tupled_args, called_in_const, called_at_rt]: [_; 3] = std::mem::take(args).try_into().unwrap();
171 let ty = tupled_args.ty(&body.local_decls, tcx);
172 let fields = ty.tuple_fields();
173 let num_args = fields.len();
174 let func = if context == hir::Constness::Const { called_in_const } else { called_at_rt };
175 let (method, place): (fn(Place<'tcx>) -> Operand<'tcx>, Place<'tcx>) = match tupled_args {
176 Operand::Constant(_) => {
177 // there is no good way of extracting a tuple arg from a constant (const generic stuff)
178 // so we just create a temporary and deconstruct that.
179 let local = body.local_decls.push(LocalDecl::new(ty, fn_span));
180 bb.statements.push(Statement {
181 source_info: SourceInfo::outermost(fn_span),
182 kind: StatementKind::Assign(Box::new((local.into(), Rvalue::Use(tupled_args.clone())))),
184 (Operand::Move, local.into())
186 Operand::Move(place) => (Operand::Move, place),
187 Operand::Copy(place) => (Operand::Copy, place),
189 let place_elems = place.projection;
190 let arguments = (0..num_args).map(|x| {
191 let mut place_elems = place_elems.to_vec();
192 place_elems.push(ProjectionElem::Field(x.into(), fields[x]));
193 let projection = tcx.intern_place_elems(&place_elems);
200 terminator.kind = TerminatorKind::Call { func, args: arguments, destination, target, cleanup, from_hir_call: false, fn_span };
208 fn is_mir_available(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
209 let def_id = def_id.expect_local();
210 tcx.mir_keys(()).contains(&def_id)
213 /// Finds the full set of `DefId`s within the current crate that have
214 /// MIR associated with them.
215 fn mir_keys(tcx: TyCtxt<'_>, (): ()) -> FxIndexSet<LocalDefId> {
216 let mut set = FxIndexSet::default();
218 // All body-owners have MIR associated with them.
219 set.extend(tcx.hir().body_owners());
221 // Additionally, tuple struct/variant constructors have MIR, but
222 // they don't have a BodyId, so we need to build them separately.
223 struct GatherCtors<'a, 'tcx> {
225 set: &'a mut FxIndexSet<LocalDefId>,
227 impl<'tcx> Visitor<'tcx> for GatherCtors<'_, 'tcx> {
228 fn visit_variant_data(&mut self, v: &'tcx hir::VariantData<'tcx>) {
229 if let hir::VariantData::Tuple(_, hir_id) = *v {
230 self.set.insert(self.tcx.hir().local_def_id(hir_id));
232 intravisit::walk_struct_def(self, v)
235 tcx.hir().visit_all_item_likes_in_crate(&mut GatherCtors { tcx, set: &mut set });
240 fn mir_const_qualif(tcx: TyCtxt<'_>, def: ty::WithOptConstParam<LocalDefId>) -> ConstQualifs {
241 let const_kind = tcx.hir().body_const_context(def.did);
243 // No need to const-check a non-const `fn`.
244 if const_kind.is_none() {
245 return Default::default();
248 // N.B., this `borrow()` is guaranteed to be valid (i.e., the value
249 // cannot yet be stolen), because `mir_promoted()`, which steals
250 // from `mir_const(), forces this query to execute before
251 // performing the steal.
252 let body = &tcx.mir_const(def).borrow();
254 if body.return_ty().references_error() {
255 tcx.sess.delay_span_bug(body.span, "mir_const_qualif: MIR had errors");
256 return Default::default();
259 let ccx = check_consts::ConstCx { body, tcx, const_kind, param_env: tcx.param_env(def.did) };
261 let mut validator = check_consts::check::Checker::new(&ccx);
262 validator.check_body();
264 // We return the qualifs in the return place for every MIR body, even though it is only used
265 // when deciding to promote a reference to a `const` for now.
266 validator.qualifs_in_return_place()
269 /// Make MIR ready for const evaluation. This is run on all MIR, not just on consts!
270 /// FIXME(oli-obk): it's unclear whether we still need this phase (and its corresponding query).
271 /// We used to have this for pre-miri MIR based const eval.
274 def: ty::WithOptConstParam<LocalDefId>,
275 ) -> &'tcx Steal<Body<'tcx>> {
276 if let Some(def) = def.try_upgrade(tcx) {
277 return tcx.mir_const(def);
280 // Unsafety check uses the raw mir, so make sure it is run.
281 if !tcx.sess.opts.unstable_opts.thir_unsafeck {
282 if let Some(param_did) = def.const_param_did {
283 tcx.ensure().unsafety_check_result_for_const_arg((def.did, param_did));
285 tcx.ensure().unsafety_check_result(def.did);
289 // has_ffi_unwind_calls query uses the raw mir, so make sure it is run.
290 tcx.ensure().has_ffi_unwind_calls(def.did);
292 let mut body = tcx.mir_built(def).steal();
294 pass_manager::dump_mir_for_phase_change(tcx, &body);
301 &Lint(check_packed_ref::CheckPackedRef),
302 &Lint(check_const_item_mutation::CheckConstItemMutation),
303 &Lint(function_item_references::FunctionItemReferences),
304 // What we need to do constant evaluation.
305 &simplify::SimplifyCfg::new("initial"),
306 &rustc_peek::SanityCheck, // Just a lint
310 tcx.alloc_steal_mir(body)
313 /// Compute the main MIR body and the list of MIR bodies of the promoteds.
314 fn mir_promoted<'tcx>(
316 def: ty::WithOptConstParam<LocalDefId>,
317 ) -> (&'tcx Steal<Body<'tcx>>, &'tcx Steal<IndexVec<Promoted, Body<'tcx>>>) {
318 if let Some(def) = def.try_upgrade(tcx) {
319 return tcx.mir_promoted(def);
322 // Ensure that we compute the `mir_const_qualif` for constants at
323 // this point, before we steal the mir-const result.
324 // Also this means promotion can rely on all const checks having been done.
325 let const_qualifs = tcx.mir_const_qualif_opt_const_arg(def);
326 let mut body = tcx.mir_const(def).steal();
327 if let Some(error_reported) = const_qualifs.tainted_by_errors {
328 body.tainted_by_errors = Some(error_reported);
331 let mut required_consts = Vec::new();
332 let mut required_consts_visitor = RequiredConstsVisitor::new(&mut required_consts);
333 for (bb, bb_data) in traversal::reverse_postorder(&body) {
334 required_consts_visitor.visit_basic_block_data(bb, bb_data);
336 body.required_consts = required_consts;
338 // What we need to run borrowck etc.
339 let promote_pass = promote_consts::PromoteTemps::default();
345 &simplify::SimplifyCfg::new("promote-consts"),
346 &coverage::InstrumentCoverage,
348 Some(MirPhase::Analysis(AnalysisPhase::Initial)),
351 let promoted = promote_pass.promoted_fragments.into_inner();
352 (tcx.alloc_steal_mir(body), tcx.alloc_steal_promoted(promoted))
355 /// Compute the MIR that is used during CTFE (and thus has no optimizations run on it)
356 fn mir_for_ctfe<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> &'tcx Body<'tcx> {
357 let did = def_id.expect_local();
358 if let Some(def) = ty::WithOptConstParam::try_lookup(did, tcx) {
359 tcx.mir_for_ctfe_of_const_arg(def)
361 tcx.arena.alloc(inner_mir_for_ctfe(tcx, ty::WithOptConstParam::unknown(did)))
365 /// Same as `mir_for_ctfe`, but used to get the MIR of a const generic parameter.
366 /// The docs on `WithOptConstParam` explain this a bit more, but the TLDR is that
367 /// we'd get cycle errors with `mir_for_ctfe`, because typeck would need to typeck
368 /// the const parameter while type checking the main body, which in turn would try
369 /// to type check the main body again.
370 fn mir_for_ctfe_of_const_arg<'tcx>(
372 (did, param_did): (LocalDefId, DefId),
373 ) -> &'tcx Body<'tcx> {
374 tcx.arena.alloc(inner_mir_for_ctfe(
376 ty::WithOptConstParam { did, const_param_did: Some(param_did) },
380 fn inner_mir_for_ctfe(tcx: TyCtxt<'_>, def: ty::WithOptConstParam<LocalDefId>) -> Body<'_> {
381 // FIXME: don't duplicate this between the optimized_mir/mir_for_ctfe queries
382 if tcx.is_constructor(def.did.to_def_id()) {
383 // There's no reason to run all of the MIR passes on constructors when
384 // we can just output the MIR we want directly. This also saves const
385 // qualification and borrow checking the trouble of special casing
387 return shim::build_adt_ctor(tcx, def.did.to_def_id());
392 .body_const_context(def.did)
393 .expect("mir_for_ctfe should not be used for runtime functions");
395 let body = tcx.mir_drops_elaborated_and_const_checked(def).borrow().clone();
397 let mut body = remap_mir_for_const_eval_select(tcx, body, hir::Constness::Const);
400 // Do not const prop functions, either they get executed at runtime or exported to metadata,
401 // so we run const prop on them, or they don't, in which case we const evaluate some control
402 // flow paths of the function and any errors in those paths will get emitted as const eval
404 hir::ConstContext::ConstFn => {}
405 // Static items always get evaluated, so we can just let const eval see if any erroneous
406 // control flow paths get executed.
407 hir::ConstContext::Static(_) => {}
408 // Associated constants get const prop run so we detect common failure situations in the
409 // crate that defined the constant.
410 // Technically we want to not run on regular const items, but oli-obk doesn't know how to
411 // conveniently detect that at this point without looking at the HIR.
412 hir::ConstContext::Const => {
416 &[&const_prop::ConstProp],
417 Some(MirPhase::Runtime(RuntimePhase::Optimized)),
422 debug_assert!(!body.has_free_regions(), "Free regions in MIR for CTFE");
427 /// Obtain just the main MIR (no promoteds) and run some cleanups on it. This also runs
428 /// mir borrowck *before* doing so in order to ensure that borrowck can be run and doesn't
429 /// end up missing the source MIR due to stealing happening.
430 fn mir_drops_elaborated_and_const_checked<'tcx>(
432 def: ty::WithOptConstParam<LocalDefId>,
433 ) -> &'tcx Steal<Body<'tcx>> {
434 if let Some(def) = def.try_upgrade(tcx) {
435 return tcx.mir_drops_elaborated_and_const_checked(def);
438 let mir_borrowck = tcx.mir_borrowck_opt_const_arg(def);
440 let is_fn_like = tcx.def_kind(def.did).is_fn_like();
442 let did = def.did.to_def_id();
443 let def = ty::WithOptConstParam::unknown(did);
445 // Do not compute the mir call graph without said call graph actually being used.
446 if inline::Inline.is_enabled(&tcx.sess) {
447 let _ = tcx.mir_inliner_callees(ty::InstanceDef::Item(def));
451 let (body, _) = tcx.mir_promoted(def);
452 let mut body = body.steal();
453 if let Some(error_reported) = mir_borrowck.tainted_by_errors {
454 body.tainted_by_errors = Some(error_reported);
457 run_analysis_to_runtime_passes(tcx, &mut body);
459 tcx.alloc_steal_mir(body)
462 fn run_analysis_to_runtime_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
463 assert!(body.phase == MirPhase::Analysis(AnalysisPhase::Initial));
464 let did = body.source.def_id();
466 debug!("analysis_mir_cleanup({:?})", did);
467 run_analysis_cleanup_passes(tcx, body);
468 assert!(body.phase == MirPhase::Analysis(AnalysisPhase::PostCleanup));
470 // Do a little drop elaboration before const-checking if `const_precise_live_drops` is enabled.
471 if check_consts::post_drop_elaboration::checking_enabled(&ConstCx::new(tcx, &body)) {
476 &remove_uninit_drops::RemoveUninitDrops,
477 &simplify::SimplifyCfg::new("remove-false-edges"),
481 check_consts::post_drop_elaboration::check_live_drops(tcx, &body); // FIXME: make this a MIR lint
484 debug!("runtime_mir_lowering({:?})", did);
485 run_runtime_lowering_passes(tcx, body);
486 assert!(body.phase == MirPhase::Runtime(RuntimePhase::Initial));
488 debug!("runtime_mir_cleanup({:?})", did);
489 run_runtime_cleanup_passes(tcx, body);
490 assert!(body.phase == MirPhase::Runtime(RuntimePhase::PostCleanup));
493 // FIXME(JakobDegen): Can we make these lists of passes consts?
495 /// After this series of passes, no lifetime analysis based on borrowing can be done.
496 fn run_analysis_cleanup_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
497 let passes: &[&dyn MirPass<'tcx>] = &[
498 &remove_false_edges::RemoveFalseEdges,
499 &simplify_branches::SimplifyConstCondition::new("initial"),
500 &remove_noop_landing_pads::RemoveNoopLandingPads,
501 &cleanup_post_borrowck::CleanupNonCodegenStatements,
502 &simplify::SimplifyCfg::new("early-opt"),
503 &deref_separator::Derefer,
506 pm::run_passes(tcx, body, passes, Some(MirPhase::Analysis(AnalysisPhase::PostCleanup)));
509 /// Returns the sequence of passes that lowers analysis to runtime MIR.
510 fn run_runtime_lowering_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
511 let passes: &[&dyn MirPass<'tcx>] = &[
512 // These next passes must be executed together
513 &add_call_guards::CriticalCallEdges,
514 &elaborate_drops::ElaborateDrops,
515 // This will remove extraneous landing pads which are no longer
516 // necessary as well as well as forcing any call in a non-unwinding
517 // function calling a possibly-unwinding function to abort the process.
518 &abort_unwinding_calls::AbortUnwindingCalls,
519 // AddMovesForPackedDrops needs to run after drop
521 &add_moves_for_packed_drops::AddMovesForPackedDrops,
522 // `AddRetag` needs to run after `ElaborateDrops`. Otherwise it should run fairly late,
523 // but before optimizations begin.
524 &elaborate_box_derefs::ElaborateBoxDerefs,
525 &generator::StateTransform,
526 &add_retag::AddRetag,
527 // Deaggregator is necessary for const prop. We may want to consider implementing
528 // CTFE support for aggregates.
529 &deaggregator::Deaggregator,
530 &Lint(const_prop_lint::ConstProp),
532 pm::run_passes_no_validate(tcx, body, passes, Some(MirPhase::Runtime(RuntimePhase::Initial)));
535 /// Returns the sequence of passes that do the initial cleanup of runtime MIR.
536 fn run_runtime_cleanup_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
537 let passes: &[&dyn MirPass<'tcx>] = &[
538 &elaborate_box_derefs::ElaborateBoxDerefs,
539 &lower_intrinsics::LowerIntrinsics,
540 &simplify::SimplifyCfg::new("elaborate-drops"),
543 pm::run_passes(tcx, body, passes, Some(MirPhase::Runtime(RuntimePhase::PostCleanup)));
546 fn run_optimization_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
547 fn o1<T>(x: T) -> WithMinOptLevel<T> {
548 WithMinOptLevel(1, x)
551 // The main optimizations that we do on MIR.
556 &reveal_all::RevealAll, // has to be done before inlining, since inlined code is in RevealAll mode.
557 &lower_slice_len::LowerSliceLenCalls, // has to be done before inlining, otherwise actual call will be almost always inlined. Also simple, so can just do first
558 &normalize_array_len::NormalizeArrayLen, // has to run after `slice::len` lowering
559 &unreachable_prop::UnreachablePropagation,
560 &uninhabited_enum_branching::UninhabitedEnumBranching,
561 &o1(simplify::SimplifyCfg::new("after-uninhabited-enum-branching")),
563 &remove_storage_markers::RemoveStorageMarkers,
564 &remove_zsts::RemoveZsts,
565 &const_goto::ConstGoto,
566 &remove_unneeded_drops::RemoveUnneededDrops,
567 &sroa::ScalarReplacementOfAggregates,
568 &match_branches::MatchBranchSimplification,
569 // inst combine is after MatchBranchSimplification to clean up Ne(_1, false)
570 &multiple_return_terminators::MultipleReturnTerminators,
571 &instcombine::InstCombine,
572 &separate_const_switch::SeparateConstSwitch,
574 // FIXME(#70073): This pass is responsible for both optimization as well as some lints.
575 &const_prop::ConstProp,
576 &dataflow_const_prop::DataflowConstProp,
578 // Const-prop runs unconditionally, but doesn't mutate the MIR at mir-opt-level=0.
579 &const_debuginfo::ConstDebugInfo,
580 &o1(simplify_branches::SimplifyConstCondition::new("after-const-prop")),
581 &early_otherwise_branch::EarlyOtherwiseBranch,
582 &simplify_comparison_integral::SimplifyComparisonIntegral,
583 &simplify_try::SimplifyArmIdentity,
584 &simplify_try::SimplifyBranchSame,
585 &dead_store_elimination::DeadStoreElimination,
586 &dest_prop::DestinationPropagation,
587 &o1(simplify_branches::SimplifyConstCondition::new("final")),
588 &o1(remove_noop_landing_pads::RemoveNoopLandingPads),
589 &o1(simplify::SimplifyCfg::new("final")),
590 &nrvo::RenameReturnPlace,
591 &simplify::SimplifyLocals,
592 &multiple_return_terminators::MultipleReturnTerminators,
593 &deduplicate_blocks::DeduplicateBlocks,
594 // Some cleanup necessary at least for LLVM and potentially other codegen backends.
595 &add_call_guards::CriticalCallEdges,
596 // Dump the end result for testing and debugging purposes.
597 &dump_mir::Marker("PreCodegen"),
599 Some(MirPhase::Runtime(RuntimePhase::Optimized)),
603 /// Optimize the MIR and prepare it for codegen.
604 fn optimized_mir<'tcx>(tcx: TyCtxt<'tcx>, did: DefId) -> &'tcx Body<'tcx> {
605 let did = did.expect_local();
606 assert_eq!(ty::WithOptConstParam::try_lookup(did, tcx), None);
607 tcx.arena.alloc(inner_optimized_mir(tcx, did))
610 fn inner_optimized_mir(tcx: TyCtxt<'_>, did: LocalDefId) -> Body<'_> {
611 if tcx.is_constructor(did.to_def_id()) {
612 // There's no reason to run all of the MIR passes on constructors when
613 // we can just output the MIR we want directly. This also saves const
614 // qualification and borrow checking the trouble of special casing
616 return shim::build_adt_ctor(tcx, did.to_def_id());
619 match tcx.hir().body_const_context(did) {
620 // Run the `mir_for_ctfe` query, which depends on `mir_drops_elaborated_and_const_checked`
621 // which we are going to steal below. Thus we need to run `mir_for_ctfe` first, so it
622 // computes and caches its result.
623 Some(hir::ConstContext::ConstFn) => tcx.ensure().mir_for_ctfe(did),
625 Some(other) => panic!("do not use `optimized_mir` for constants: {:?}", other),
627 debug!("about to call mir_drops_elaborated...");
629 tcx.mir_drops_elaborated_and_const_checked(ty::WithOptConstParam::unknown(did)).steal();
630 let mut body = remap_mir_for_const_eval_select(tcx, body, hir::Constness::NotConst);
631 debug!("body: {:#?}", body);
632 run_optimization_passes(tcx, &mut body);
634 debug_assert!(!body.has_free_regions(), "Free regions in optimized MIR");
639 /// Fetch all the promoteds of an item and prepare their MIR bodies to be ready for
640 /// constant evaluation once all substitutions become known.
641 fn promoted_mir<'tcx>(
643 def: ty::WithOptConstParam<LocalDefId>,
644 ) -> &'tcx IndexVec<Promoted, Body<'tcx>> {
645 if tcx.is_constructor(def.did.to_def_id()) {
646 return tcx.arena.alloc(IndexVec::new());
649 let tainted_by_errors = tcx.mir_borrowck_opt_const_arg(def).tainted_by_errors;
650 let mut promoted = tcx.mir_promoted(def).1.steal();
652 for body in &mut promoted {
653 if let Some(error_reported) = tainted_by_errors {
654 body.tainted_by_errors = Some(error_reported);
656 run_analysis_to_runtime_passes(tcx, body);
659 debug_assert!(!promoted.has_free_regions(), "Free regions in promoted MIR");
661 tcx.arena.alloc(promoted)