1 //! Inlining pass for MIR functions
3 use rustc_attr::InlineAttr;
5 use rustc_index::bit_set::BitSet;
6 use rustc_index::vec::Idx;
7 use rustc_middle::middle::codegen_fn_attrs::{CodegenFnAttrFlags, CodegenFnAttrs};
8 use rustc_middle::mir::visit::*;
9 use rustc_middle::mir::*;
10 use rustc_middle::traits::ObligationCause;
11 use rustc_middle::ty::subst::Subst;
12 use rustc_middle::ty::{self, ConstKind, Instance, InstanceDef, ParamEnv, Ty, TyCtxt};
13 use rustc_span::{hygiene::ExpnKind, ExpnData, Span};
14 use rustc_target::spec::abi::Abi;
16 use super::simplify::{remove_dead_blocks, CfgSimplifier};
19 use std::ops::{Range, RangeFrom};
23 const INSTR_COST: usize = 5;
24 const CALL_PENALTY: usize = 25;
25 const LANDINGPAD_PENALTY: usize = 50;
26 const RESUME_PENALTY: usize = 45;
28 const UNKNOWN_SIZE_COST: usize = 10;
32 #[derive(Copy, Clone, Debug)]
33 struct CallSite<'tcx> {
34 callee: Instance<'tcx>,
35 fn_sig: ty::PolyFnSig<'tcx>,
37 target: Option<BasicBlock>,
38 source_info: SourceInfo,
41 impl<'tcx> MirPass<'tcx> for Inline {
42 fn is_enabled(&self, sess: &rustc_session::Session) -> bool {
43 if let Some(enabled) = sess.opts.debugging_opts.inline_mir {
47 sess.opts.mir_opt_level() >= 3
50 fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
51 let span = trace_span!("inline", body = %tcx.def_path_str(body.source.def_id()));
52 let _guard = span.enter();
53 if inline(tcx, body) {
54 debug!("running simplify cfg on {:?}", body.source);
55 CfgSimplifier::new(body).simplify();
56 remove_dead_blocks(tcx, body);
61 fn inline<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) -> bool {
62 let def_id = body.source.def_id();
63 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
65 // Only do inlining into fn bodies.
66 if !tcx.hir().body_owner_kind(hir_id).is_fn_or_closure() {
69 if body.source.promoted.is_some() {
72 // Avoid inlining into generators, since their `optimized_mir` is used for layout computation,
73 // which can create a cycle, even when no attempt is made to inline the function in the other
75 if body.generator.is_some() {
79 let param_env = tcx.param_env_reveal_all_normalized(def_id);
80 let param_env = rustc_trait_selection::traits::normalize_param_env_or_error(
84 ObligationCause::misc(body.span, hir_id),
87 let mut this = Inliner {
90 codegen_fn_attrs: tcx.codegen_fn_attrs(def_id),
95 let blocks = BasicBlock::new(0)..body.basic_blocks().next_index();
96 this.process_blocks(body, blocks);
100 struct Inliner<'tcx> {
102 param_env: ParamEnv<'tcx>,
103 /// Caller codegen attributes.
104 codegen_fn_attrs: &'tcx CodegenFnAttrs,
107 /// Stack of inlined Instances.
108 history: Vec<ty::Instance<'tcx>>,
109 /// Indicates that the caller body has been modified.
113 impl<'tcx> Inliner<'tcx> {
114 fn process_blocks(&mut self, caller_body: &mut Body<'tcx>, blocks: Range<BasicBlock>) {
116 let bb_data = &caller_body[bb];
117 if bb_data.is_cleanup {
121 let callsite = match self.resolve_callsite(caller_body, bb, bb_data) {
126 let span = trace_span!("process_blocks", %callsite.callee, ?bb);
127 let _guard = span.enter();
129 match self.try_inlining(caller_body, &callsite) {
131 debug!("not-inlined {} [{}]", callsite.callee, reason);
135 debug!("inlined {}", callsite.callee);
137 self.history.push(callsite.callee);
138 self.process_blocks(caller_body, new_blocks);
145 /// Attempts to inline a callsite into the caller body. When successful returns basic blocks
146 /// containing the inlined body. Otherwise returns an error describing why inlining didn't take
150 caller_body: &mut Body<'tcx>,
151 callsite: &CallSite<'tcx>,
152 ) -> Result<std::ops::Range<BasicBlock>, &'static str> {
153 let callee_attrs = self.tcx.codegen_fn_attrs(callsite.callee.def_id());
154 self.check_codegen_attributes(callsite, callee_attrs)?;
155 self.check_mir_is_available(caller_body, &callsite.callee)?;
156 let callee_body = self.tcx.instance_mir(callsite.callee.def);
157 self.check_mir_body(callsite, callee_body, callee_attrs)?;
159 if !self.tcx.consider_optimizing(|| {
160 format!("Inline {:?} into {:?}", callsite.callee, caller_body.source)
162 return Err("optimization fuel exhausted");
165 let callee_body = callsite.callee.subst_mir_and_normalize_erasing_regions(
171 let old_blocks = caller_body.basic_blocks().next_index();
172 self.inline_call(caller_body, &callsite, callee_body);
173 let new_blocks = old_blocks..caller_body.basic_blocks().next_index();
178 fn check_mir_is_available(
180 caller_body: &Body<'tcx>,
181 callee: &Instance<'tcx>,
182 ) -> Result<(), &'static str> {
183 if callee.def_id() == caller_body.source.def_id() {
184 return Err("self-recursion");
188 InstanceDef::Item(_) => {
189 // If there is no MIR available (either because it was not in metadata or
190 // because it has no MIR because it's an extern function), then the inliner
191 // won't cause cycles on this.
192 if !self.tcx.is_mir_available(callee.def_id()) {
193 return Err("item MIR unavailable");
196 // These have no own callable MIR.
197 InstanceDef::Intrinsic(_) | InstanceDef::Virtual(..) => {
198 return Err("instance without MIR (intrinsic / virtual)");
200 // This cannot result in an immediate cycle since the callee MIR is a shim, which does
201 // not get any optimizations run on it. Any subsequent inlining may cause cycles, but we
202 // do not need to catch this here, we can wait until the inliner decides to continue
203 // inlining a second time.
204 InstanceDef::VtableShim(_)
205 | InstanceDef::ReifyShim(_)
206 | InstanceDef::FnPtrShim(..)
207 | InstanceDef::ClosureOnceShim { .. }
208 | InstanceDef::DropGlue(..)
209 | InstanceDef::CloneShim(..) => return Ok(()),
212 if self.tcx.is_constructor(callee.def_id()) {
213 trace!("constructors always have MIR");
214 // Constructor functions cannot cause a query cycle.
218 if let Some(callee_def_id) = callee.def_id().as_local() {
219 let callee_hir_id = self.tcx.hir().local_def_id_to_hir_id(callee_def_id);
220 // Avoid a cycle here by only using `instance_mir` only if we have
221 // a lower `HirId` than the callee. This ensures that the callee will
222 // not inline us. This trick only works without incremental compilation.
223 // So don't do it if that is enabled.
224 if !self.tcx.dep_graph.is_fully_enabled() && self.hir_id.index() < callee_hir_id.index()
229 // If we know for sure that the function we're calling will itself try to
230 // call us, then we avoid inlining that function.
233 .mir_callgraph_reachable((*callee, caller_body.source.def_id().expect_local()))
235 return Err("caller might be reachable from callee (query cycle avoidance)");
240 // This cannot result in an immediate cycle since the callee MIR is from another crate
241 // and is already optimized. Any subsequent inlining may cause cycles, but we do
242 // not need to catch this here, we can wait until the inliner decides to continue
243 // inlining a second time.
244 trace!("functions from other crates always have MIR");
251 caller_body: &Body<'tcx>,
253 bb_data: &BasicBlockData<'tcx>,
254 ) -> Option<CallSite<'tcx>> {
255 // Only consider direct calls to functions
256 let terminator = bb_data.terminator();
257 if let TerminatorKind::Call { ref func, ref destination, .. } = terminator.kind {
258 let func_ty = func.ty(caller_body, self.tcx);
259 if let ty::FnDef(def_id, substs) = *func_ty.kind() {
260 // To resolve an instance its substs have to be fully normalized.
261 let substs = self.tcx.normalize_erasing_regions(self.param_env, substs);
263 Instance::resolve(self.tcx, self.param_env, def_id, substs).ok().flatten()?;
265 if let InstanceDef::Virtual(..) | InstanceDef::Intrinsic(_) = callee.def {
269 let fn_sig = self.tcx.fn_sig(def_id).subst(self.tcx, substs);
271 return Some(CallSite {
275 target: destination.map(|(_, target)| target),
276 source_info: terminator.source_info,
284 /// Returns an error if inlining is not possible based on codegen attributes alone. A success
285 /// indicates that inlining decision should be based on other criteria.
286 fn check_codegen_attributes(
288 callsite: &CallSite<'tcx>,
289 callee_attrs: &CodegenFnAttrs,
290 ) -> Result<(), &'static str> {
291 if let InlineAttr::Never = callee_attrs.inline {
292 return Err("never inline hint");
295 // Only inline local functions if they would be eligible for cross-crate
296 // inlining. This is to ensure that the final crate doesn't have MIR that
297 // reference unexported symbols
298 if callsite.callee.def_id().is_local() {
299 let is_generic = callsite.callee.substs.non_erasable_generics().next().is_some();
300 if !is_generic && !callee_attrs.requests_inline() {
301 return Err("not exported");
305 if callsite.fn_sig.c_variadic() {
306 return Err("C variadic");
309 if callee_attrs.flags.contains(CodegenFnAttrFlags::NAKED) {
313 if callee_attrs.flags.contains(CodegenFnAttrFlags::COLD) {
317 if callee_attrs.no_sanitize != self.codegen_fn_attrs.no_sanitize {
318 return Err("incompatible sanitizer set");
321 if callee_attrs.instruction_set != self.codegen_fn_attrs.instruction_set {
322 return Err("incompatible instruction set");
325 for feature in &callee_attrs.target_features {
326 if !self.codegen_fn_attrs.target_features.contains(feature) {
327 return Err("incompatible target feature");
334 /// Returns inlining decision that is based on the examination of callee MIR body.
335 /// Assumes that codegen attributes have been checked for compatibility already.
336 #[instrument(level = "debug", skip(self, callee_body))]
339 callsite: &CallSite<'tcx>,
340 callee_body: &Body<'tcx>,
341 callee_attrs: &CodegenFnAttrs,
342 ) -> Result<(), &'static str> {
345 let mut threshold = if callee_attrs.requests_inline() {
346 self.tcx.sess.opts.debugging_opts.inline_mir_hint_threshold.unwrap_or(100)
348 self.tcx.sess.opts.debugging_opts.inline_mir_threshold.unwrap_or(50)
351 // Give a bonus functions with a small number of blocks,
352 // We normally have two or three blocks for even
353 // very small functions.
354 if callee_body.basic_blocks().len() <= 3 {
355 threshold += threshold / 4;
357 debug!(" final inline threshold = {}", threshold);
359 // FIXME: Give a bonus to functions with only a single caller
360 let mut first_block = true;
363 // Traverse the MIR manually so we can account for the effects of
364 // inlining on the CFG.
365 let mut work_list = vec![START_BLOCK];
366 let mut visited = BitSet::new_empty(callee_body.basic_blocks().len());
367 while let Some(bb) = work_list.pop() {
368 if !visited.insert(bb.index()) {
371 let blk = &callee_body.basic_blocks()[bb];
373 for stmt in &blk.statements {
374 // Don't count StorageLive/StorageDead in the inlining cost.
376 StatementKind::StorageLive(_)
377 | StatementKind::StorageDead(_)
378 | StatementKind::Nop => {}
379 _ => cost += INSTR_COST,
382 let term = blk.terminator();
383 let mut is_drop = false;
385 TerminatorKind::Drop { ref place, target, unwind }
386 | TerminatorKind::DropAndReplace { ref place, target, unwind, .. } => {
388 work_list.push(target);
389 // If the place doesn't actually need dropping, treat it like
391 let ty = callsite.callee.subst_mir(self.tcx, &place.ty(callee_body, tcx).ty);
392 if ty.needs_drop(tcx, self.param_env) {
393 cost += CALL_PENALTY;
394 if let Some(unwind) = unwind {
395 cost += LANDINGPAD_PENALTY;
396 work_list.push(unwind);
403 TerminatorKind::Unreachable | TerminatorKind::Call { destination: None, .. }
406 // If the function always diverges, don't inline
407 // unless the cost is zero
411 TerminatorKind::Call { func: Operand::Constant(ref f), cleanup, .. } => {
412 if let ty::FnDef(def_id, substs) =
413 *callsite.callee.subst_mir(self.tcx, &f.literal.ty()).kind()
415 let substs = self.tcx.normalize_erasing_regions(self.param_env, substs);
416 if let Ok(Some(instance)) =
417 Instance::resolve(self.tcx, self.param_env, def_id, substs)
419 if callsite.callee.def_id() == instance.def_id() {
420 return Err("self-recursion");
421 } else if self.history.contains(&instance) {
422 return Err("already inlined");
425 // Don't give intrinsics the extra penalty for calls
426 let f = tcx.fn_sig(def_id);
427 if f.abi() == Abi::RustIntrinsic || f.abi() == Abi::PlatformIntrinsic {
430 cost += CALL_PENALTY;
433 cost += CALL_PENALTY;
435 if cleanup.is_some() {
436 cost += LANDINGPAD_PENALTY;
439 TerminatorKind::Assert { cleanup, .. } => {
440 cost += CALL_PENALTY;
442 if cleanup.is_some() {
443 cost += LANDINGPAD_PENALTY;
446 TerminatorKind::Resume => cost += RESUME_PENALTY,
447 TerminatorKind::InlineAsm { cleanup, .. } => {
450 if cleanup.is_some() {
451 cost += LANDINGPAD_PENALTY;
454 _ => cost += INSTR_COST,
458 for &succ in term.successors() {
459 work_list.push(succ);
466 // Count up the cost of local variables and temps, if we know the size
467 // use that, otherwise we use a moderately-large dummy cost.
469 let ptr_size = tcx.data_layout.pointer_size.bytes();
471 for v in callee_body.vars_and_temps_iter() {
472 let ty = callsite.callee.subst_mir(self.tcx, &callee_body.local_decls[v].ty);
473 // Cost of the var is the size in machine-words, if we know
475 if let Some(size) = type_size_of(tcx, self.param_env, ty) {
476 cost += ((size + ptr_size - 1) / ptr_size) as usize;
478 cost += UNKNOWN_SIZE_COST;
482 if let InlineAttr::Always = callee_attrs.inline {
483 debug!("INLINING {:?} because inline(always) [cost={}]", callsite, cost);
486 if cost <= threshold {
487 debug!("INLINING {:?} [cost={} <= threshold={}]", callsite, cost, threshold);
490 debug!("NOT inlining {:?} [cost={} > threshold={}]", callsite, cost, threshold);
491 Err("cost above threshold")
498 caller_body: &mut Body<'tcx>,
499 callsite: &CallSite<'tcx>,
500 mut callee_body: Body<'tcx>,
502 let terminator = caller_body[callsite.block].terminator.take().unwrap();
503 match terminator.kind {
504 TerminatorKind::Call { args, destination, cleanup, .. } => {
505 // If the call is something like `a[*i] = f(i)`, where
506 // `i : &mut usize`, then just duplicating the `a[*i]`
507 // Place could result in two different locations if `f`
508 // writes to `i`. To prevent this we need to create a temporary
509 // borrow of the place and pass the destination as `*temp` instead.
510 fn dest_needs_borrow(place: Place<'_>) -> bool {
511 for elem in place.projection.iter() {
513 ProjectionElem::Deref | ProjectionElem::Index(_) => return true,
521 let dest = if let Some((destination_place, _)) = destination {
522 if dest_needs_borrow(destination_place) {
523 trace!("creating temp for return destination");
524 let dest = Rvalue::Ref(
525 self.tcx.lifetimes.re_erased,
526 BorrowKind::Mut { allow_two_phase_borrow: false },
529 let dest_ty = dest.ty(caller_body, self.tcx);
530 let temp = Place::from(self.new_call_temp(caller_body, &callsite, dest_ty));
531 caller_body[callsite.block].statements.push(Statement {
532 source_info: callsite.source_info,
533 kind: StatementKind::Assign(Box::new((temp, dest))),
535 self.tcx.mk_place_deref(temp)
540 trace!("creating temp for return place");
541 Place::from(self.new_call_temp(caller_body, &callsite, callee_body.return_ty()))
544 // Copy the arguments if needed.
545 let args: Vec<_> = self.make_call_args(args, &callsite, caller_body, &callee_body);
547 let mut integrator = Integrator {
549 new_locals: Local::new(caller_body.local_decls.len())..,
550 new_scopes: SourceScope::new(caller_body.source_scopes.len())..,
551 new_blocks: BasicBlock::new(caller_body.basic_blocks().len())..,
553 return_block: callsite.target,
554 cleanup_block: cleanup,
555 in_cleanup_block: false,
557 callsite_span: callsite.source_info.span,
558 body_span: callee_body.span,
559 always_live_locals: BitSet::new_filled(callee_body.local_decls.len()),
562 // Map all `Local`s, `SourceScope`s and `BasicBlock`s to new ones
563 // (or existing ones, in a few special cases) in the caller.
564 integrator.visit_body(&mut callee_body);
566 for scope in &mut callee_body.source_scopes {
567 // FIXME(eddyb) move this into a `fn visit_scope_data` in `Integrator`.
568 if scope.parent_scope.is_none() {
569 let callsite_scope = &caller_body.source_scopes[callsite.source_info.scope];
571 // Attach the outermost callee scope as a child of the callsite
572 // scope, via the `parent_scope` and `inlined_parent_scope` chains.
573 scope.parent_scope = Some(callsite.source_info.scope);
574 assert_eq!(scope.inlined_parent_scope, None);
575 scope.inlined_parent_scope = if callsite_scope.inlined.is_some() {
576 Some(callsite.source_info.scope)
578 callsite_scope.inlined_parent_scope
581 // Mark the outermost callee scope as an inlined one.
582 assert_eq!(scope.inlined, None);
583 scope.inlined = Some((callsite.callee, callsite.source_info.span));
584 } else if scope.inlined_parent_scope.is_none() {
585 // Make it easy to find the scope with `inlined` set above.
586 scope.inlined_parent_scope =
587 Some(integrator.map_scope(OUTERMOST_SOURCE_SCOPE));
591 // If there are any locals without storage markers, give them storage only for the
592 // duration of the call.
593 for local in callee_body.vars_and_temps_iter() {
594 if integrator.always_live_locals.contains(local) {
595 let new_local = integrator.map_local(local);
596 caller_body[callsite.block].statements.push(Statement {
597 source_info: callsite.source_info,
598 kind: StatementKind::StorageLive(new_local),
602 if let Some(block) = callsite.target {
603 // To avoid repeated O(n) insert, push any new statements to the end and rotate
606 for local in callee_body.vars_and_temps_iter().rev() {
607 if integrator.always_live_locals.contains(local) {
608 let new_local = integrator.map_local(local);
609 caller_body[block].statements.push(Statement {
610 source_info: callsite.source_info,
611 kind: StatementKind::StorageDead(new_local),
616 caller_body[block].statements.rotate_right(n);
619 // Insert all of the (mapped) parts of the callee body into the caller.
620 caller_body.local_decls.extend(callee_body.drain_vars_and_temps());
621 caller_body.source_scopes.extend(&mut callee_body.source_scopes.drain(..));
622 caller_body.var_debug_info.append(&mut callee_body.var_debug_info);
623 caller_body.basic_blocks_mut().extend(callee_body.basic_blocks_mut().drain(..));
625 caller_body[callsite.block].terminator = Some(Terminator {
626 source_info: callsite.source_info,
627 kind: TerminatorKind::Goto { target: integrator.map_block(START_BLOCK) },
630 // Copy only unevaluated constants from the callee_body into the caller_body.
631 // Although we are only pushing `ConstKind::Unevaluated` consts to
632 // `required_consts`, here we may not only have `ConstKind::Unevaluated`
633 // because we are calling `subst_and_normalize_erasing_regions`.
634 caller_body.required_consts.extend(
635 callee_body.required_consts.iter().copied().filter(|&ct| {
636 match ct.literal.const_for_ty() {
637 Some(ct) => matches!(ct.val(), ConstKind::Unevaluated(_)),
643 kind => bug!("unexpected terminator kind {:?}", kind),
649 args: Vec<Operand<'tcx>>,
650 callsite: &CallSite<'tcx>,
651 caller_body: &mut Body<'tcx>,
652 callee_body: &Body<'tcx>,
656 // There is a bit of a mismatch between the *caller* of a closure and the *callee*.
657 // The caller provides the arguments wrapped up in a tuple:
659 // tuple_tmp = (a, b, c)
660 // Fn::call(closure_ref, tuple_tmp)
662 // meanwhile the closure body expects the arguments (here, `a`, `b`, and `c`)
663 // as distinct arguments. (This is the "rust-call" ABI hack.) Normally, codegen has
664 // the job of unpacking this tuple. But here, we are codegen. =) So we want to create
667 // [closure_ref, tuple_tmp.0, tuple_tmp.1, tuple_tmp.2]
669 // Except for one tiny wrinkle: we don't actually want `tuple_tmp.0`. It's more convenient
670 // if we "spill" that into *another* temporary, so that we can map the argument
671 // variable in the callee MIR directly to an argument variable on our side.
672 // So we introduce temporaries like:
674 // tmp0 = tuple_tmp.0
675 // tmp1 = tuple_tmp.1
676 // tmp2 = tuple_tmp.2
678 // and the vector is `[closure_ref, tmp0, tmp1, tmp2]`.
679 if callsite.fn_sig.abi() == Abi::RustCall && callee_body.spread_arg.is_none() {
680 let mut args = args.into_iter();
681 let self_ = self.create_temp_if_necessary(args.next().unwrap(), callsite, caller_body);
682 let tuple = self.create_temp_if_necessary(args.next().unwrap(), callsite, caller_body);
683 assert!(args.next().is_none());
685 let tuple = Place::from(tuple);
686 let ty::Tuple(tuple_tys) = tuple.ty(caller_body, tcx).ty.kind() else {
687 bug!("Closure arguments are not passed as a tuple");
690 // The `closure_ref` in our example above.
691 let closure_ref_arg = iter::once(self_);
693 // The `tmp0`, `tmp1`, and `tmp2` in our example abonve.
694 let tuple_tmp_args = tuple_tys.iter().enumerate().map(|(i, ty)| {
695 // This is e.g., `tuple_tmp.0` in our example above.
697 Operand::Move(tcx.mk_place_field(tuple, Field::new(i), ty.expect_ty()));
699 // Spill to a local to make e.g., `tmp0`.
700 self.create_temp_if_necessary(tuple_field, callsite, caller_body)
703 closure_ref_arg.chain(tuple_tmp_args).collect()
706 .map(|a| self.create_temp_if_necessary(a, callsite, caller_body))
711 /// If `arg` is already a temporary, returns it. Otherwise, introduces a fresh
712 /// temporary `T` and an instruction `T = arg`, and returns `T`.
713 fn create_temp_if_necessary(
716 callsite: &CallSite<'tcx>,
717 caller_body: &mut Body<'tcx>,
719 // Reuse the operand if it is a moved temporary.
720 if let Operand::Move(place) = &arg {
721 if let Some(local) = place.as_local() {
722 if caller_body.local_kind(local) == LocalKind::Temp {
728 // Otherwise, create a temporary for the argument.
729 trace!("creating temp for argument {:?}", arg);
730 let arg_ty = arg.ty(caller_body, self.tcx);
731 let local = self.new_call_temp(caller_body, callsite, arg_ty);
732 caller_body[callsite.block].statements.push(Statement {
733 source_info: callsite.source_info,
734 kind: StatementKind::Assign(Box::new((Place::from(local), Rvalue::Use(arg)))),
739 /// Introduces a new temporary into the caller body that is live for the duration of the call.
742 caller_body: &mut Body<'tcx>,
743 callsite: &CallSite<'tcx>,
746 let local = caller_body.local_decls.push(LocalDecl::new(ty, callsite.source_info.span));
748 caller_body[callsite.block].statements.push(Statement {
749 source_info: callsite.source_info,
750 kind: StatementKind::StorageLive(local),
753 if let Some(block) = callsite.target {
754 caller_body[block].statements.insert(
757 source_info: callsite.source_info,
758 kind: StatementKind::StorageDead(local),
767 fn type_size_of<'tcx>(
769 param_env: ty::ParamEnv<'tcx>,
772 tcx.layout_of(param_env.and(ty)).ok().map(|layout| layout.size.bytes())
778 * Integrates blocks from the callee function into the calling function.
779 * Updates block indices, references to locals and other control flow
782 struct Integrator<'a, 'tcx> {
784 new_locals: RangeFrom<Local>,
785 new_scopes: RangeFrom<SourceScope>,
786 new_blocks: RangeFrom<BasicBlock>,
787 destination: Place<'tcx>,
788 return_block: Option<BasicBlock>,
789 cleanup_block: Option<BasicBlock>,
790 in_cleanup_block: bool,
794 always_live_locals: BitSet<Local>,
797 impl Integrator<'_, '_> {
798 fn map_local(&self, local: Local) -> Local {
799 let new = if local == RETURN_PLACE {
800 self.destination.local
802 let idx = local.index() - 1;
803 if idx < self.args.len() {
806 Local::new(self.new_locals.start.index() + (idx - self.args.len()))
809 trace!("mapping local `{:?}` to `{:?}`", local, new);
813 fn map_scope(&self, scope: SourceScope) -> SourceScope {
814 let new = SourceScope::new(self.new_scopes.start.index() + scope.index());
815 trace!("mapping scope `{:?}` to `{:?}`", scope, new);
819 fn map_block(&self, block: BasicBlock) -> BasicBlock {
820 let new = BasicBlock::new(self.new_blocks.start.index() + block.index());
821 trace!("mapping block `{:?}` to `{:?}`", block, new);
826 impl<'tcx> MutVisitor<'tcx> for Integrator<'_, 'tcx> {
827 fn tcx(&self) -> TyCtxt<'tcx> {
831 fn visit_local(&mut self, local: &mut Local, _ctxt: PlaceContext, _location: Location) {
832 *local = self.map_local(*local);
835 fn visit_source_scope(&mut self, scope: &mut SourceScope) {
836 *scope = self.map_scope(*scope);
839 fn visit_span(&mut self, span: &mut Span) {
841 ExpnData::default(ExpnKind::Inlined, *span, self.tcx.sess.edition(), None, None);
842 expn_data.def_site = self.body_span;
843 // Make sure that all spans track the fact that they were inlined.
845 self.callsite_span.fresh_expansion(expn_data, self.tcx.create_stable_hashing_context());
848 fn visit_place(&mut self, place: &mut Place<'tcx>, context: PlaceContext, location: Location) {
849 for elem in place.projection {
850 // FIXME: Make sure that return place is not used in an indexing projection, since it
851 // won't be rebased as it is supposed to be.
852 assert_ne!(ProjectionElem::Index(RETURN_PLACE), elem);
855 // If this is the `RETURN_PLACE`, we need to rebase any projections onto it.
856 let dest_proj_len = self.destination.projection.len();
857 if place.local == RETURN_PLACE && dest_proj_len > 0 {
858 let mut projs = Vec::with_capacity(dest_proj_len + place.projection.len());
859 projs.extend(self.destination.projection);
860 projs.extend(place.projection);
862 place.projection = self.tcx.intern_place_elems(&*projs);
864 // Handles integrating any locals that occur in the base
866 self.super_place(place, context, location)
869 fn visit_basic_block_data(&mut self, block: BasicBlock, data: &mut BasicBlockData<'tcx>) {
870 self.in_cleanup_block = data.is_cleanup;
871 self.super_basic_block_data(block, data);
872 self.in_cleanup_block = false;
875 fn visit_retag(&mut self, kind: &mut RetagKind, place: &mut Place<'tcx>, loc: Location) {
876 self.super_retag(kind, place, loc);
878 // We have to patch all inlined retags to be aware that they are no longer
879 // happening on function entry.
880 if *kind == RetagKind::FnEntry {
881 *kind = RetagKind::Default;
885 fn visit_statement(&mut self, statement: &mut Statement<'tcx>, location: Location) {
886 if let StatementKind::StorageLive(local) | StatementKind::StorageDead(local) =
889 self.always_live_locals.remove(local);
891 self.super_statement(statement, location);
894 fn visit_terminator(&mut self, terminator: &mut Terminator<'tcx>, loc: Location) {
895 // Don't try to modify the implicit `_0` access on return (`return` terminators are
896 // replaced down below anyways).
897 if !matches!(terminator.kind, TerminatorKind::Return) {
898 self.super_terminator(terminator, loc);
901 match terminator.kind {
902 TerminatorKind::GeneratorDrop | TerminatorKind::Yield { .. } => bug!(),
903 TerminatorKind::Goto { ref mut target } => {
904 *target = self.map_block(*target);
906 TerminatorKind::SwitchInt { ref mut targets, .. } => {
907 for tgt in targets.all_targets_mut() {
908 *tgt = self.map_block(*tgt);
911 TerminatorKind::Drop { ref mut target, ref mut unwind, .. }
912 | TerminatorKind::DropAndReplace { ref mut target, ref mut unwind, .. } => {
913 *target = self.map_block(*target);
914 if let Some(tgt) = *unwind {
915 *unwind = Some(self.map_block(tgt));
916 } else if !self.in_cleanup_block {
917 // Unless this drop is in a cleanup block, add an unwind edge to
918 // the original call's cleanup block
919 *unwind = self.cleanup_block;
922 TerminatorKind::Call { ref mut destination, ref mut cleanup, .. } => {
923 if let Some((_, ref mut tgt)) = *destination {
924 *tgt = self.map_block(*tgt);
926 if let Some(tgt) = *cleanup {
927 *cleanup = Some(self.map_block(tgt));
928 } else if !self.in_cleanup_block {
929 // Unless this call is in a cleanup block, add an unwind edge to
930 // the original call's cleanup block
931 *cleanup = self.cleanup_block;
934 TerminatorKind::Assert { ref mut target, ref mut cleanup, .. } => {
935 *target = self.map_block(*target);
936 if let Some(tgt) = *cleanup {
937 *cleanup = Some(self.map_block(tgt));
938 } else if !self.in_cleanup_block {
939 // Unless this assert is in a cleanup block, add an unwind edge to
940 // the original call's cleanup block
941 *cleanup = self.cleanup_block;
944 TerminatorKind::Return => {
945 terminator.kind = if let Some(tgt) = self.return_block {
946 TerminatorKind::Goto { target: tgt }
948 TerminatorKind::Unreachable
951 TerminatorKind::Resume => {
952 if let Some(tgt) = self.cleanup_block {
953 terminator.kind = TerminatorKind::Goto { target: tgt }
956 TerminatorKind::Abort => {}
957 TerminatorKind::Unreachable => {}
958 TerminatorKind::FalseEdge { ref mut real_target, ref mut imaginary_target } => {
959 *real_target = self.map_block(*real_target);
960 *imaginary_target = self.map_block(*imaginary_target);
962 TerminatorKind::FalseUnwind { real_target: _, unwind: _ } =>
963 // see the ordering of passes in the optimized_mir query.
965 bug!("False unwinds should have been removed before inlining")
967 TerminatorKind::InlineAsm { ref mut destination, ref mut cleanup, .. } => {
968 if let Some(ref mut tgt) = *destination {
969 *tgt = self.map_block(*tgt);
970 } else if !self.in_cleanup_block {
971 // Unless this inline asm is in a cleanup block, add an unwind edge to
972 // the original call's cleanup block
973 *cleanup = self.cleanup_block;