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::ty::subst::Subst;
11 use rustc_middle::ty::{self, ConstKind, Instance, InstanceDef, ParamEnv, Ty, TyCtxt};
12 use rustc_span::{hygiene::ExpnKind, ExpnData, Span};
13 use rustc_target::spec::abi::Abi;
15 use super::simplify::{remove_dead_blocks, CfgSimplifier};
16 use crate::transform::MirPass;
18 use std::ops::{Range, RangeFrom};
22 const INSTR_COST: usize = 5;
23 const CALL_PENALTY: usize = 25;
24 const LANDINGPAD_PENALTY: usize = 50;
25 const RESUME_PENALTY: usize = 45;
27 const UNKNOWN_SIZE_COST: usize = 10;
31 #[derive(Copy, Clone, Debug)]
32 struct CallSite<'tcx> {
33 callee: Instance<'tcx>,
34 fn_sig: ty::PolyFnSig<'tcx>,
36 target: Option<BasicBlock>,
37 source_info: SourceInfo,
40 /// Returns true if MIR inlining is enabled in the current compilation session.
41 crate fn is_enabled(tcx: TyCtxt<'_>) -> bool {
42 if let Some(enabled) = tcx.sess.opts.debugging_opts.inline_mir {
46 tcx.sess.mir_opt_level() >= 3
49 impl<'tcx> MirPass<'tcx> for Inline {
50 fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
55 let span = trace_span!("inline", body = %tcx.def_path_str(body.source.def_id()));
56 let _guard = span.enter();
57 if inline(tcx, body) {
58 debug!("running simplify cfg on {:?}", body.source);
59 CfgSimplifier::new(body).simplify();
60 remove_dead_blocks(body);
65 fn inline(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) -> bool {
66 let def_id = body.source.def_id();
67 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
69 // Only do inlining into fn bodies.
70 if !tcx.hir().body_owner_kind(hir_id).is_fn_or_closure() {
73 if body.source.promoted.is_some() {
77 let mut this = Inliner {
79 param_env: tcx.param_env_reveal_all_normalized(body.source.def_id()),
80 codegen_fn_attrs: tcx.codegen_fn_attrs(body.source.def_id()),
85 let blocks = BasicBlock::new(0)..body.basic_blocks().next_index();
86 this.process_blocks(body, blocks);
90 struct Inliner<'tcx> {
92 param_env: ParamEnv<'tcx>,
93 /// Caller codegen attributes.
94 codegen_fn_attrs: &'tcx CodegenFnAttrs,
97 /// Stack of inlined Instances.
98 history: Vec<ty::Instance<'tcx>>,
99 /// Indicates that the caller body has been modified.
104 fn process_blocks(&mut self, caller_body: &mut Body<'tcx>, blocks: Range<BasicBlock>) {
106 let bb_data = &caller_body[bb];
107 if bb_data.is_cleanup {
111 let callsite = match self.resolve_callsite(caller_body, bb, bb_data) {
116 let span = trace_span!("process_blocks", %callsite.callee, ?bb);
117 let _guard = span.enter();
119 match self.try_inlining(caller_body, &callsite) {
121 debug!("not-inlined {} [{}]", callsite.callee, reason);
125 debug!("inlined {}", callsite.callee);
127 self.history.push(callsite.callee);
128 self.process_blocks(caller_body, new_blocks);
135 /// Attempts to inline a callsite into the caller body. When successful returns basic blocks
136 /// containing the inlined body. Otherwise returns an error describing why inlining didn't take
140 caller_body: &mut Body<'tcx>,
141 callsite: &CallSite<'tcx>,
142 ) -> Result<std::ops::Range<BasicBlock>, &'static str> {
143 let callee_attrs = self.tcx.codegen_fn_attrs(callsite.callee.def_id());
144 self.check_codegen_attributes(callsite, callee_attrs)?;
145 self.check_mir_is_available(caller_body, &callsite.callee)?;
146 let callee_body = self.tcx.instance_mir(callsite.callee.def);
147 self.check_mir_body(callsite, callee_body, callee_attrs)?;
149 if !self.tcx.consider_optimizing(|| {
150 format!("Inline {:?} into {}", callee_body.span, callsite.callee)
152 return Err("optimization fuel exhausted");
155 let callee_body = callsite.callee.subst_mir_and_normalize_erasing_regions(
161 let old_blocks = caller_body.basic_blocks().next_index();
162 self.inline_call(caller_body, &callsite, callee_body);
163 let new_blocks = old_blocks..caller_body.basic_blocks().next_index();
168 fn check_mir_is_available(
170 caller_body: &Body<'tcx>,
171 callee: &Instance<'tcx>,
172 ) -> Result<(), &'static str> {
173 if callee.def_id() == caller_body.source.def_id() {
174 return Err("self-recursion");
178 InstanceDef::Item(_) => {
179 // If there is no MIR available (either because it was not in metadata or
180 // because it has no MIR because it's an extern function), then the inliner
181 // won't cause cycles on this.
182 if !self.tcx.is_mir_available(callee.def_id()) {
183 return Err("item MIR unavailable");
186 // These have no own callable MIR.
187 InstanceDef::Intrinsic(_) | InstanceDef::Virtual(..) => {
188 return Err("instance without MIR (intrinsic / virtual)");
190 // This cannot result in an immediate cycle since the callee MIR is a shim, which does
191 // not get any optimizations run on it. Any subsequent inlining may cause cycles, but we
192 // do not need to catch this here, we can wait until the inliner decides to continue
193 // inlining a second time.
194 InstanceDef::VtableShim(_)
195 | InstanceDef::ReifyShim(_)
196 | InstanceDef::FnPtrShim(..)
197 | InstanceDef::ClosureOnceShim { .. }
198 | InstanceDef::DropGlue(..)
199 | InstanceDef::CloneShim(..) => return Ok(()),
202 if self.tcx.is_constructor(callee.def_id()) {
203 trace!("constructors always have MIR");
204 // Constructor functions cannot cause a query cycle.
208 if let Some(callee_def_id) = callee.def_id().as_local() {
209 let callee_hir_id = self.tcx.hir().local_def_id_to_hir_id(callee_def_id);
210 // Avoid inlining into generators,
211 // since their `optimized_mir` is used for layout computation, which can
212 // create a cycle, even when no attempt is made to inline the function
213 // in the other direction.
214 if caller_body.generator.is_some() {
215 return Err("local generator (query cycle avoidance)");
218 // Avoid a cycle here by only using `instance_mir` only if we have
219 // a lower `HirId` than the callee. This ensures that the callee will
220 // not inline us. This trick only works without incremental compilation.
221 // So don't do it if that is enabled.
222 if !self.tcx.dep_graph.is_fully_enabled() && self.hir_id < callee_hir_id {
226 // If we know for sure that the function we're calling will itself try to
227 // call us, then we avoid inlining that function.
230 .mir_callgraph_reachable((*callee, caller_body.source.def_id().expect_local()))
232 return Err("caller might be reachable from callee (query cycle avoidance)");
237 // This cannot result in an immediate cycle since the callee MIR is from another crate
238 // and is already optimized. Any subsequent inlining may cause cycles, but we do
239 // not need to catch this here, we can wait until the inliner decides to continue
240 // inlining a second time.
241 trace!("functions from other crates always have MIR");
248 caller_body: &Body<'tcx>,
250 bb_data: &BasicBlockData<'tcx>,
251 ) -> Option<CallSite<'tcx>> {
252 // Only consider direct calls to functions
253 let terminator = bb_data.terminator();
254 if let TerminatorKind::Call { ref func, ref destination, .. } = terminator.kind {
255 let func_ty = func.ty(caller_body, self.tcx);
256 if let ty::FnDef(def_id, substs) = *func_ty.kind() {
257 // To resolve an instance its substs have to be fully normalized.
258 let substs = self.tcx.normalize_erasing_regions(self.param_env, substs);
260 Instance::resolve(self.tcx, self.param_env, def_id, substs).ok().flatten()?;
262 if let InstanceDef::Virtual(..) | InstanceDef::Intrinsic(_) = callee.def {
266 let fn_sig = self.tcx.fn_sig(def_id).subst(self.tcx, substs);
268 return Some(CallSite {
272 target: destination.map(|(_, target)| target),
273 source_info: terminator.source_info,
281 /// Returns an error if inlining is not possible based on codegen attributes alone. A success
282 /// indicates that inlining decision should be based on other criteria.
283 fn check_codegen_attributes(
285 callsite: &CallSite<'tcx>,
286 callee_attrs: &CodegenFnAttrs,
287 ) -> Result<(), &'satic str> {
288 if let InlineAttr::Never = callee_attrs.inline {
289 return Err("never inline hint");
292 // Only inline local functions if they would be eligible for cross-crate
293 // inlining. This is to ensure that the final crate doesn't have MIR that
294 // reference unexported symbols
295 if callsite.callee.def_id().is_local() {
296 let is_generic = callsite.callee.substs.non_erasable_generics().next().is_some();
297 if !is_generic && !callee_attrs.requests_inline() {
298 return Err("not exported");
302 if callsite.fn_sig.c_variadic() {
303 return Err("C variadic");
306 if callee_attrs.flags.contains(CodegenFnAttrFlags::NAKED) {
310 if callee_attrs.flags.contains(CodegenFnAttrFlags::COLD) {
314 if callee_attrs.no_sanitize != self.codegen_fn_attrs.no_sanitize {
315 return Err("incompatible sanitizer set");
318 if callee_attrs.instruction_set != self.codegen_fn_attrs.instruction_set {
319 return Err("incompatible instruction set");
322 for feature in &callee_attrs.target_features {
323 if !self.codegen_fn_attrs.target_features.contains(feature) {
324 return Err("incompatible target feature");
331 /// Returns inlining decision that is based on the examination of callee MIR body.
332 /// Assumes that codegen attributes have been checked for compatibility already.
333 #[instrument(level = "debug", skip(self, callee_body))]
336 callsite: &CallSite<'tcx>,
337 callee_body: &Body<'tcx>,
338 callee_attrs: &CodegenFnAttrs,
339 ) -> Result<(), &'static str> {
342 let mut threshold = if callee_attrs.requests_inline() {
343 self.tcx.sess.opts.debugging_opts.inline_mir_hint_threshold.unwrap_or(100)
345 self.tcx.sess.opts.debugging_opts.inline_mir_threshold.unwrap_or(50)
348 // Give a bonus functions with a small number of blocks,
349 // We normally have two or three blocks for even
350 // very small functions.
351 if callee_body.basic_blocks().len() <= 3 {
352 threshold += threshold / 4;
354 debug!(" final inline threshold = {}", threshold);
356 // FIXME: Give a bonus to functions with only a single caller
357 let mut first_block = true;
360 // Traverse the MIR manually so we can account for the effects of
361 // inlining on the CFG.
362 let mut work_list = vec![START_BLOCK];
363 let mut visited = BitSet::new_empty(callee_body.basic_blocks().len());
364 while let Some(bb) = work_list.pop() {
365 if !visited.insert(bb.index()) {
368 let blk = &callee_body.basic_blocks()[bb];
370 for stmt in &blk.statements {
371 // Don't count StorageLive/StorageDead in the inlining cost.
373 StatementKind::StorageLive(_)
374 | StatementKind::StorageDead(_)
375 | StatementKind::Nop => {}
376 _ => cost += INSTR_COST,
379 let term = blk.terminator();
380 let mut is_drop = false;
382 TerminatorKind::Drop { ref place, target, unwind }
383 | TerminatorKind::DropAndReplace { ref place, target, unwind, .. } => {
385 work_list.push(target);
386 // If the place doesn't actually need dropping, treat it like
388 let ty = callsite.callee.subst_mir(self.tcx, &place.ty(callee_body, tcx).ty);
389 if ty.needs_drop(tcx, self.param_env) {
390 cost += CALL_PENALTY;
391 if let Some(unwind) = unwind {
392 cost += LANDINGPAD_PENALTY;
393 work_list.push(unwind);
400 TerminatorKind::Unreachable | TerminatorKind::Call { destination: None, .. }
403 // If the function always diverges, don't inline
404 // unless the cost is zero
408 TerminatorKind::Call { func: Operand::Constant(ref f), cleanup, .. } => {
409 if let ty::FnDef(def_id, substs) =
410 *callsite.callee.subst_mir(self.tcx, &f.literal.ty()).kind()
412 let substs = self.tcx.normalize_erasing_regions(self.param_env, substs);
413 if let Ok(Some(instance)) =
414 Instance::resolve(self.tcx, self.param_env, def_id, substs)
416 if callsite.callee.def_id() == instance.def_id() {
417 return Err("self-recursion");
418 } else if self.history.contains(&instance) {
419 return Err("already inlined");
422 // Don't give intrinsics the extra penalty for calls
423 let f = tcx.fn_sig(def_id);
424 if f.abi() == Abi::RustIntrinsic || f.abi() == Abi::PlatformIntrinsic {
427 cost += CALL_PENALTY;
430 cost += CALL_PENALTY;
432 if cleanup.is_some() {
433 cost += LANDINGPAD_PENALTY;
436 TerminatorKind::Assert { cleanup, .. } => {
437 cost += CALL_PENALTY;
439 if cleanup.is_some() {
440 cost += LANDINGPAD_PENALTY;
443 TerminatorKind::Resume => cost += RESUME_PENALTY,
444 _ => cost += INSTR_COST,
448 for &succ in term.successors() {
449 work_list.push(succ);
456 // Count up the cost of local variables and temps, if we know the size
457 // use that, otherwise we use a moderately-large dummy cost.
459 let ptr_size = tcx.data_layout.pointer_size.bytes();
461 for v in callee_body.vars_and_temps_iter() {
462 let ty = callsite.callee.subst_mir(self.tcx, &callee_body.local_decls[v].ty);
463 // Cost of the var is the size in machine-words, if we know
465 if let Some(size) = type_size_of(tcx, self.param_env, ty) {
466 cost += ((size + ptr_size - 1) / ptr_size) as usize;
468 cost += UNKNOWN_SIZE_COST;
472 if let InlineAttr::Always = callee_attrs.inline {
473 debug!("INLINING {:?} because inline(always) [cost={}]", callsite, cost);
476 if cost <= threshold {
477 debug!("INLINING {:?} [cost={} <= threshold={}]", callsite, cost, threshold);
480 debug!("NOT inlining {:?} [cost={} > threshold={}]", callsite, cost, threshold);
481 Err("cost above threshold")
488 caller_body: &mut Body<'tcx>,
489 callsite: &CallSite<'tcx>,
490 mut callee_body: Body<'tcx>,
492 let terminator = caller_body[callsite.block].terminator.take().unwrap();
493 match terminator.kind {
494 TerminatorKind::Call { args, destination, cleanup, .. } => {
495 // If the call is something like `a[*i] = f(i)`, where
496 // `i : &mut usize`, then just duplicating the `a[*i]`
497 // Place could result in two different locations if `f`
498 // writes to `i`. To prevent this we need to create a temporary
499 // borrow of the place and pass the destination as `*temp` instead.
500 fn dest_needs_borrow(place: Place<'_>) -> bool {
501 for elem in place.projection.iter() {
503 ProjectionElem::Deref | ProjectionElem::Index(_) => return true,
511 let dest = if let Some((destination_place, _)) = destination {
512 if dest_needs_borrow(destination_place) {
513 trace!("creating temp for return destination");
514 let dest = Rvalue::Ref(
515 self.tcx.lifetimes.re_erased,
516 BorrowKind::Mut { allow_two_phase_borrow: false },
519 let dest_ty = dest.ty(caller_body, self.tcx);
520 let temp = Place::from(self.new_call_temp(caller_body, &callsite, dest_ty));
521 caller_body[callsite.block].statements.push(Statement {
522 source_info: callsite.source_info,
523 kind: StatementKind::Assign(box (temp, dest)),
525 self.tcx.mk_place_deref(temp)
530 trace!("creating temp for return place");
531 Place::from(self.new_call_temp(caller_body, &callsite, callee_body.return_ty()))
534 // Copy the arguments if needed.
535 let args: Vec<_> = self.make_call_args(args, &callsite, caller_body, &callee_body);
537 let mut integrator = Integrator {
539 new_locals: Local::new(caller_body.local_decls.len())..,
540 new_scopes: SourceScope::new(caller_body.source_scopes.len())..,
541 new_blocks: BasicBlock::new(caller_body.basic_blocks().len())..,
543 return_block: callsite.target,
544 cleanup_block: cleanup,
545 in_cleanup_block: false,
547 callsite_span: callsite.source_info.span,
548 body_span: callee_body.span,
549 always_live_locals: BitSet::new_filled(callee_body.local_decls.len()),
552 // Map all `Local`s, `SourceScope`s and `BasicBlock`s to new ones
553 // (or existing ones, in a few special cases) in the caller.
554 integrator.visit_body(&mut callee_body);
556 for scope in &mut callee_body.source_scopes {
557 // FIXME(eddyb) move this into a `fn visit_scope_data` in `Integrator`.
558 if scope.parent_scope.is_none() {
559 let callsite_scope = &caller_body.source_scopes[callsite.source_info.scope];
561 // Attach the outermost callee scope as a child of the callsite
562 // scope, via the `parent_scope` and `inlined_parent_scope` chains.
563 scope.parent_scope = Some(callsite.source_info.scope);
564 assert_eq!(scope.inlined_parent_scope, None);
565 scope.inlined_parent_scope = if callsite_scope.inlined.is_some() {
566 Some(callsite.source_info.scope)
568 callsite_scope.inlined_parent_scope
571 // Mark the outermost callee scope as an inlined one.
572 assert_eq!(scope.inlined, None);
573 scope.inlined = Some((callsite.callee, callsite.source_info.span));
574 } else if scope.inlined_parent_scope.is_none() {
575 // Make it easy to find the scope with `inlined` set above.
576 scope.inlined_parent_scope =
577 Some(integrator.map_scope(OUTERMOST_SOURCE_SCOPE));
581 // If there are any locals without storage markers, give them storage only for the
582 // duration of the call.
583 for local in callee_body.vars_and_temps_iter() {
584 if integrator.always_live_locals.contains(local) {
585 let new_local = integrator.map_local(local);
586 caller_body[callsite.block].statements.push(Statement {
587 source_info: callsite.source_info,
588 kind: StatementKind::StorageLive(new_local),
592 if let Some(block) = callsite.target {
593 // To avoid repeated O(n) insert, push any new statements to the end and rotate
596 for local in callee_body.vars_and_temps_iter().rev() {
597 if integrator.always_live_locals.contains(local) {
598 let new_local = integrator.map_local(local);
599 caller_body[block].statements.push(Statement {
600 source_info: callsite.source_info,
601 kind: StatementKind::StorageDead(new_local),
606 caller_body[block].statements.rotate_right(n);
609 // Insert all of the (mapped) parts of the callee body into the caller.
610 caller_body.local_decls.extend(
611 // FIXME(eddyb) make `Range<Local>` iterable so that we can use
612 // `callee_body.local_decls.drain(callee_body.vars_and_temps())`
614 .vars_and_temps_iter()
615 .map(|local| callee_body.local_decls[local].clone()),
617 caller_body.source_scopes.extend(callee_body.source_scopes.drain(..));
618 caller_body.var_debug_info.extend(callee_body.var_debug_info.drain(..));
619 caller_body.basic_blocks_mut().extend(callee_body.basic_blocks_mut().drain(..));
621 caller_body[callsite.block].terminator = Some(Terminator {
622 source_info: callsite.source_info,
623 kind: TerminatorKind::Goto { target: integrator.map_block(START_BLOCK) },
626 // Copy only unevaluated constants from the callee_body into the caller_body.
627 // Although we are only pushing `ConstKind::Unevaluated` consts to
628 // `required_consts`, here we may not only have `ConstKind::Unevaluated`
629 // because we are calling `subst_and_normalize_erasing_regions`.
630 caller_body.required_consts.extend(
631 callee_body.required_consts.iter().copied().filter(|&ct| {
632 match ct.literal.const_for_ty() {
633 Some(ct) => matches!(ct.val, ConstKind::Unevaluated(_)),
639 kind => bug!("unexpected terminator kind {:?}", kind),
645 args: Vec<Operand<'tcx>>,
646 callsite: &CallSite<'tcx>,
647 caller_body: &mut Body<'tcx>,
648 callee_body: &Body<'tcx>,
652 // There is a bit of a mismatch between the *caller* of a closure and the *callee*.
653 // The caller provides the arguments wrapped up in a tuple:
655 // tuple_tmp = (a, b, c)
656 // Fn::call(closure_ref, tuple_tmp)
658 // meanwhile the closure body expects the arguments (here, `a`, `b`, and `c`)
659 // as distinct arguments. (This is the "rust-call" ABI hack.) Normally, codegen has
660 // the job of unpacking this tuple. But here, we are codegen. =) So we want to create
663 // [closure_ref, tuple_tmp.0, tuple_tmp.1, tuple_tmp.2]
665 // Except for one tiny wrinkle: we don't actually want `tuple_tmp.0`. It's more convenient
666 // if we "spill" that into *another* temporary, so that we can map the argument
667 // variable in the callee MIR directly to an argument variable on our side.
668 // So we introduce temporaries like:
670 // tmp0 = tuple_tmp.0
671 // tmp1 = tuple_tmp.1
672 // tmp2 = tuple_tmp.2
674 // and the vector is `[closure_ref, tmp0, tmp1, tmp2]`.
675 if callsite.fn_sig.abi() == Abi::RustCall && callee_body.spread_arg.is_none() {
676 let mut args = args.into_iter();
677 let self_ = self.create_temp_if_necessary(args.next().unwrap(), callsite, caller_body);
678 let tuple = self.create_temp_if_necessary(args.next().unwrap(), callsite, caller_body);
679 assert!(args.next().is_none());
681 let tuple = Place::from(tuple);
682 let tuple_tys = if let ty::Tuple(s) = tuple.ty(caller_body, tcx).ty.kind() {
685 bug!("Closure arguments are not passed as a tuple");
688 // The `closure_ref` in our example above.
689 let closure_ref_arg = iter::once(self_);
691 // The `tmp0`, `tmp1`, and `tmp2` in our example abonve.
692 let tuple_tmp_args = tuple_tys.iter().enumerate().map(|(i, ty)| {
693 // This is e.g., `tuple_tmp.0` in our example above.
695 Operand::Move(tcx.mk_place_field(tuple, Field::new(i), ty.expect_ty()));
697 // Spill to a local to make e.g., `tmp0`.
698 self.create_temp_if_necessary(tuple_field, callsite, caller_body)
701 closure_ref_arg.chain(tuple_tmp_args).collect()
704 .map(|a| self.create_temp_if_necessary(a, callsite, caller_body))
709 /// If `arg` is already a temporary, returns it. Otherwise, introduces a fresh
710 /// temporary `T` and an instruction `T = arg`, and returns `T`.
711 fn create_temp_if_necessary(
714 callsite: &CallSite<'tcx>,
715 caller_body: &mut Body<'tcx>,
717 // Reuse the operand if it is a moved temporary.
718 if let Operand::Move(place) = &arg {
719 if let Some(local) = place.as_local() {
720 if caller_body.local_kind(local) == LocalKind::Temp {
726 // Otherwise, create a temporary for the argument.
727 trace!("creating temp for argument {:?}", arg);
728 let arg_ty = arg.ty(caller_body, self.tcx);
729 let local = self.new_call_temp(caller_body, callsite, arg_ty);
730 caller_body[callsite.block].statements.push(Statement {
731 source_info: callsite.source_info,
732 kind: StatementKind::Assign(box (Place::from(local), Rvalue::Use(arg))),
737 /// Introduces a new temporary into the caller body that is live for the duration of the call.
740 caller_body: &mut Body<'tcx>,
741 callsite: &CallSite<'tcx>,
744 let local = caller_body.local_decls.push(LocalDecl::new(ty, callsite.source_info.span));
746 caller_body[callsite.block].statements.push(Statement {
747 source_info: callsite.source_info,
748 kind: StatementKind::StorageLive(local),
751 if let Some(block) = callsite.target {
752 caller_body[block].statements.insert(
755 source_info: callsite.source_info,
756 kind: StatementKind::StorageDead(local),
765 fn type_size_of<'tcx>(
767 param_env: ty::ParamEnv<'tcx>,
770 tcx.layout_of(param_env.and(ty)).ok().map(|layout| layout.size.bytes())
776 * Integrates blocks from the callee function into the calling function.
777 * Updates block indices, references to locals and other control flow
780 struct Integrator<'a, 'tcx> {
782 new_locals: RangeFrom<Local>,
783 new_scopes: RangeFrom<SourceScope>,
784 new_blocks: RangeFrom<BasicBlock>,
785 destination: Place<'tcx>,
786 return_block: Option<BasicBlock>,
787 cleanup_block: Option<BasicBlock>,
788 in_cleanup_block: bool,
792 always_live_locals: BitSet<Local>,
795 impl<'a, 'tcx> Integrator<'a, 'tcx> {
796 fn map_local(&self, local: Local) -> Local {
797 let new = if local == RETURN_PLACE {
798 self.destination.local
800 let idx = local.index() - 1;
801 if idx < self.args.len() {
804 Local::new(self.new_locals.start.index() + (idx - self.args.len()))
807 trace!("mapping local `{:?}` to `{:?}`", local, new);
811 fn map_scope(&self, scope: SourceScope) -> SourceScope {
812 let new = SourceScope::new(self.new_scopes.start.index() + scope.index());
813 trace!("mapping scope `{:?}` to `{:?}`", scope, new);
817 fn map_block(&self, block: BasicBlock) -> BasicBlock {
818 let new = BasicBlock::new(self.new_blocks.start.index() + block.index());
819 trace!("mapping block `{:?}` to `{:?}`", block, new);
824 impl<'a, 'tcx> MutVisitor<'tcx> for Integrator<'a, 'tcx> {
825 fn tcx(&self) -> TyCtxt<'tcx> {
829 fn visit_local(&mut self, local: &mut Local, _ctxt: PlaceContext, _location: Location) {
830 *local = self.map_local(*local);
833 fn visit_source_scope(&mut self, scope: &mut SourceScope) {
834 *scope = self.map_scope(*scope);
837 fn visit_span(&mut self, span: &mut Span) {
839 ExpnData::default(ExpnKind::Inlined, *span, self.tcx.sess.edition(), None);
840 expn_data.def_site = self.body_span;
841 // Make sure that all spans track the fact that they were inlined.
842 *span = self.callsite_span.fresh_expansion(expn_data);
845 fn visit_place(&mut self, place: &mut Place<'tcx>, context: PlaceContext, location: Location) {
846 for elem in place.projection {
847 // FIXME: Make sure that return place is not used in an indexing projection, since it
848 // won't be rebased as it is supposed to be.
849 assert_ne!(ProjectionElem::Index(RETURN_PLACE), elem);
852 // If this is the `RETURN_PLACE`, we need to rebase any projections onto it.
853 let dest_proj_len = self.destination.projection.len();
854 if place.local == RETURN_PLACE && dest_proj_len > 0 {
855 let mut projs = Vec::with_capacity(dest_proj_len + place.projection.len());
856 projs.extend(self.destination.projection);
857 projs.extend(place.projection);
859 place.projection = self.tcx.intern_place_elems(&*projs);
861 // Handles integrating any locals that occur in the base
863 self.super_place(place, context, location)
866 fn visit_basic_block_data(&mut self, block: BasicBlock, data: &mut BasicBlockData<'tcx>) {
867 self.in_cleanup_block = data.is_cleanup;
868 self.super_basic_block_data(block, data);
869 self.in_cleanup_block = false;
872 fn visit_retag(&mut self, kind: &mut RetagKind, place: &mut Place<'tcx>, loc: Location) {
873 self.super_retag(kind, place, loc);
875 // We have to patch all inlined retags to be aware that they are no longer
876 // happening on function entry.
877 if *kind == RetagKind::FnEntry {
878 *kind = RetagKind::Default;
882 fn visit_statement(&mut self, statement: &mut Statement<'tcx>, location: Location) {
883 if let StatementKind::StorageLive(local) | StatementKind::StorageDead(local) =
886 self.always_live_locals.remove(local);
888 self.super_statement(statement, location);
891 fn visit_terminator(&mut self, terminator: &mut Terminator<'tcx>, loc: Location) {
892 // Don't try to modify the implicit `_0` access on return (`return` terminators are
893 // replaced down below anyways).
894 if !matches!(terminator.kind, TerminatorKind::Return) {
895 self.super_terminator(terminator, loc);
898 match terminator.kind {
899 TerminatorKind::GeneratorDrop | TerminatorKind::Yield { .. } => bug!(),
900 TerminatorKind::Goto { ref mut target } => {
901 *target = self.map_block(*target);
903 TerminatorKind::SwitchInt { ref mut targets, .. } => {
904 for tgt in targets.all_targets_mut() {
905 *tgt = self.map_block(*tgt);
908 TerminatorKind::Drop { ref mut target, ref mut unwind, .. }
909 | TerminatorKind::DropAndReplace { ref mut target, ref mut unwind, .. } => {
910 *target = self.map_block(*target);
911 if let Some(tgt) = *unwind {
912 *unwind = Some(self.map_block(tgt));
913 } else if !self.in_cleanup_block {
914 // Unless this drop is in a cleanup block, add an unwind edge to
915 // the original call's cleanup block
916 *unwind = self.cleanup_block;
919 TerminatorKind::Call { ref mut destination, ref mut cleanup, .. } => {
920 if let Some((_, ref mut tgt)) = *destination {
921 *tgt = self.map_block(*tgt);
923 if let Some(tgt) = *cleanup {
924 *cleanup = Some(self.map_block(tgt));
925 } else if !self.in_cleanup_block {
926 // Unless this call is in a cleanup block, add an unwind edge to
927 // the original call's cleanup block
928 *cleanup = self.cleanup_block;
931 TerminatorKind::Assert { ref mut target, ref mut cleanup, .. } => {
932 *target = self.map_block(*target);
933 if let Some(tgt) = *cleanup {
934 *cleanup = Some(self.map_block(tgt));
935 } else if !self.in_cleanup_block {
936 // Unless this assert is in a cleanup block, add an unwind edge to
937 // the original call's cleanup block
938 *cleanup = self.cleanup_block;
941 TerminatorKind::Return => {
942 terminator.kind = if let Some(tgt) = self.return_block {
943 TerminatorKind::Goto { target: tgt }
945 TerminatorKind::Unreachable
948 TerminatorKind::Resume => {
949 if let Some(tgt) = self.cleanup_block {
950 terminator.kind = TerminatorKind::Goto { target: tgt }
953 TerminatorKind::Abort => {}
954 TerminatorKind::Unreachable => {}
955 TerminatorKind::FalseEdge { ref mut real_target, ref mut imaginary_target } => {
956 *real_target = self.map_block(*real_target);
957 *imaginary_target = self.map_block(*imaginary_target);
959 TerminatorKind::FalseUnwind { real_target: _, unwind: _ } =>
960 // see the ordering of passes in the optimized_mir query.
962 bug!("False unwinds should have been removed before inlining")
964 TerminatorKind::InlineAsm { ref mut destination, .. } => {
965 if let Some(ref mut tgt) = *destination {
966 *tgt = self.map_block(*tgt);