//! Inlining pass for MIR functions use rustc_attr::InlineAttr; use rustc_hir as hir; use rustc_index::bit_set::BitSet; use rustc_index::vec::Idx; use rustc_middle::middle::codegen_fn_attrs::{CodegenFnAttrFlags, CodegenFnAttrs}; use rustc_middle::mir::visit::*; use rustc_middle::mir::*; use rustc_middle::traits::ObligationCause; use rustc_middle::ty::subst::Subst; use rustc_middle::ty::{self, ConstKind, Instance, InstanceDef, ParamEnv, Ty, TyCtxt}; use rustc_span::{hygiene::ExpnKind, ExpnData, LocalExpnId, Span}; use rustc_target::spec::abi::Abi; use super::simplify::{remove_dead_blocks, CfgSimplifier}; use crate::MirPass; use std::iter; use std::ops::{Range, RangeFrom}; crate mod cycle; const INSTR_COST: usize = 5; const CALL_PENALTY: usize = 25; const LANDINGPAD_PENALTY: usize = 50; const RESUME_PENALTY: usize = 45; const UNKNOWN_SIZE_COST: usize = 10; pub struct Inline; #[derive(Copy, Clone, Debug)] struct CallSite<'tcx> { callee: Instance<'tcx>, fn_sig: ty::PolyFnSig<'tcx>, block: BasicBlock, target: Option, source_info: SourceInfo, } impl<'tcx> MirPass<'tcx> for Inline { fn is_enabled(&self, sess: &rustc_session::Session) -> bool { if let Some(enabled) = sess.opts.debugging_opts.inline_mir { return enabled; } sess.opts.mir_opt_level() >= 3 } fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) { let span = trace_span!("inline", body = %tcx.def_path_str(body.source.def_id())); let _guard = span.enter(); if inline(tcx, body) { debug!("running simplify cfg on {:?}", body.source); CfgSimplifier::new(body).simplify(); remove_dead_blocks(tcx, body); } } } fn inline<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) -> bool { let def_id = body.source.def_id().expect_local(); // Only do inlining into fn bodies. if !tcx.hir().body_owner_kind(def_id).is_fn_or_closure() { return false; } if body.source.promoted.is_some() { return false; } // Avoid inlining into generators, since their `optimized_mir` is used for layout computation, // which can create a cycle, even when no attempt is made to inline the function in the other // direction. if body.generator.is_some() { return false; } let param_env = tcx.param_env_reveal_all_normalized(def_id); let hir_id = tcx.hir().local_def_id_to_hir_id(def_id); let param_env = rustc_trait_selection::traits::normalize_param_env_or_error( tcx, def_id.to_def_id(), param_env, ObligationCause::misc(body.span, hir_id), ); let mut this = Inliner { tcx, param_env, codegen_fn_attrs: tcx.codegen_fn_attrs(def_id), hir_id, history: Vec::new(), changed: false, }; let blocks = BasicBlock::new(0)..body.basic_blocks().next_index(); this.process_blocks(body, blocks); this.changed } struct Inliner<'tcx> { tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>, /// Caller codegen attributes. codegen_fn_attrs: &'tcx CodegenFnAttrs, /// Caller HirID. hir_id: hir::HirId, /// Stack of inlined Instances. history: Vec>, /// Indicates that the caller body has been modified. changed: bool, } impl<'tcx> Inliner<'tcx> { fn process_blocks(&mut self, caller_body: &mut Body<'tcx>, blocks: Range) { for bb in blocks { let bb_data = &caller_body[bb]; if bb_data.is_cleanup { continue; } let Some(callsite) = self.resolve_callsite(caller_body, bb, bb_data) else { continue; }; let span = trace_span!("process_blocks", %callsite.callee, ?bb); let _guard = span.enter(); match self.try_inlining(caller_body, &callsite) { Err(reason) => { debug!("not-inlined {} [{}]", callsite.callee, reason); continue; } Ok(new_blocks) => { debug!("inlined {}", callsite.callee); self.changed = true; self.history.push(callsite.callee); self.process_blocks(caller_body, new_blocks); self.history.pop(); } } } } /// Attempts to inline a callsite into the caller body. When successful returns basic blocks /// containing the inlined body. Otherwise returns an error describing why inlining didn't take /// place. fn try_inlining( &self, caller_body: &mut Body<'tcx>, callsite: &CallSite<'tcx>, ) -> Result, &'static str> { let callee_attrs = self.tcx.codegen_fn_attrs(callsite.callee.def_id()); self.check_codegen_attributes(callsite, callee_attrs)?; self.check_mir_is_available(caller_body, &callsite.callee)?; let callee_body = self.tcx.instance_mir(callsite.callee.def); self.check_mir_body(callsite, callee_body, callee_attrs)?; if !self.tcx.consider_optimizing(|| { format!("Inline {:?} into {:?}", callsite.callee, caller_body.source) }) { return Err("optimization fuel exhausted"); } let callee_body = callsite.callee.subst_mir_and_normalize_erasing_regions( self.tcx, self.param_env, callee_body.clone(), ); let old_blocks = caller_body.basic_blocks().next_index(); self.inline_call(caller_body, &callsite, callee_body); let new_blocks = old_blocks..caller_body.basic_blocks().next_index(); Ok(new_blocks) } fn check_mir_is_available( &self, caller_body: &Body<'tcx>, callee: &Instance<'tcx>, ) -> Result<(), &'static str> { if callee.def_id() == caller_body.source.def_id() { return Err("self-recursion"); } match callee.def { InstanceDef::Item(_) => { // If there is no MIR available (either because it was not in metadata or // because it has no MIR because it's an extern function), then the inliner // won't cause cycles on this. if !self.tcx.is_mir_available(callee.def_id()) { return Err("item MIR unavailable"); } } // These have no own callable MIR. InstanceDef::Intrinsic(_) | InstanceDef::Virtual(..) => { return Err("instance without MIR (intrinsic / virtual)"); } // This cannot result in an immediate cycle since the callee MIR is a shim, which does // not get any optimizations run on it. Any subsequent inlining may cause cycles, but we // do not need to catch this here, we can wait until the inliner decides to continue // inlining a second time. InstanceDef::VtableShim(_) | InstanceDef::ReifyShim(_) | InstanceDef::FnPtrShim(..) | InstanceDef::ClosureOnceShim { .. } | InstanceDef::DropGlue(..) | InstanceDef::CloneShim(..) => return Ok(()), } if self.tcx.is_constructor(callee.def_id()) { trace!("constructors always have MIR"); // Constructor functions cannot cause a query cycle. return Ok(()); } if let Some(callee_def_id) = callee.def_id().as_local() { let callee_hir_id = self.tcx.hir().local_def_id_to_hir_id(callee_def_id); // Avoid a cycle here by only using `instance_mir` only if we have // a lower `HirId` than the callee. This ensures that the callee will // not inline us. This trick only works without incremental compilation. // So don't do it if that is enabled. if !self.tcx.dep_graph.is_fully_enabled() && self.hir_id.index() < callee_hir_id.index() { return Ok(()); } // If we know for sure that the function we're calling will itself try to // call us, then we avoid inlining that function. if self .tcx .mir_callgraph_reachable((*callee, caller_body.source.def_id().expect_local())) { return Err("caller might be reachable from callee (query cycle avoidance)"); } Ok(()) } else { // This cannot result in an immediate cycle since the callee MIR is from another crate // and is already optimized. Any subsequent inlining may cause cycles, but we do // not need to catch this here, we can wait until the inliner decides to continue // inlining a second time. trace!("functions from other crates always have MIR"); Ok(()) } } fn resolve_callsite( &self, caller_body: &Body<'tcx>, bb: BasicBlock, bb_data: &BasicBlockData<'tcx>, ) -> Option> { // Only consider direct calls to functions let terminator = bb_data.terminator(); if let TerminatorKind::Call { ref func, ref destination, .. } = terminator.kind { let func_ty = func.ty(caller_body, self.tcx); if let ty::FnDef(def_id, substs) = *func_ty.kind() { // To resolve an instance its substs have to be fully normalized. let substs = self.tcx.normalize_erasing_regions(self.param_env, substs); let callee = Instance::resolve(self.tcx, self.param_env, def_id, substs).ok().flatten()?; if let InstanceDef::Virtual(..) | InstanceDef::Intrinsic(_) = callee.def { return None; } let fn_sig = self.tcx.fn_sig(def_id).subst(self.tcx, substs); return Some(CallSite { callee, fn_sig, block: bb, target: destination.map(|(_, target)| target), source_info: terminator.source_info, }); } } None } /// Returns an error if inlining is not possible based on codegen attributes alone. A success /// indicates that inlining decision should be based on other criteria. fn check_codegen_attributes( &self, callsite: &CallSite<'tcx>, callee_attrs: &CodegenFnAttrs, ) -> Result<(), &'static str> { if let InlineAttr::Never = callee_attrs.inline { return Err("never inline hint"); } // Only inline local functions if they would be eligible for cross-crate // inlining. This is to ensure that the final crate doesn't have MIR that // reference unexported symbols if callsite.callee.def_id().is_local() { let is_generic = callsite.callee.substs.non_erasable_generics().next().is_some(); if !is_generic && !callee_attrs.requests_inline() { return Err("not exported"); } } if callsite.fn_sig.c_variadic() { return Err("C variadic"); } if callee_attrs.flags.contains(CodegenFnAttrFlags::NAKED) { return Err("naked"); } if callee_attrs.flags.contains(CodegenFnAttrFlags::COLD) { return Err("cold"); } if callee_attrs.no_sanitize != self.codegen_fn_attrs.no_sanitize { return Err("incompatible sanitizer set"); } if callee_attrs.instruction_set != self.codegen_fn_attrs.instruction_set { return Err("incompatible instruction set"); } for feature in &callee_attrs.target_features { if !self.codegen_fn_attrs.target_features.contains(feature) { return Err("incompatible target feature"); } } Ok(()) } /// Returns inlining decision that is based on the examination of callee MIR body. /// Assumes that codegen attributes have been checked for compatibility already. #[instrument(level = "debug", skip(self, callee_body))] fn check_mir_body( &self, callsite: &CallSite<'tcx>, callee_body: &Body<'tcx>, callee_attrs: &CodegenFnAttrs, ) -> Result<(), &'static str> { let tcx = self.tcx; let mut threshold = if callee_attrs.requests_inline() { self.tcx.sess.opts.debugging_opts.inline_mir_hint_threshold.unwrap_or(100) } else { self.tcx.sess.opts.debugging_opts.inline_mir_threshold.unwrap_or(50) }; // Give a bonus functions with a small number of blocks, // We normally have two or three blocks for even // very small functions. if callee_body.basic_blocks().len() <= 3 { threshold += threshold / 4; } debug!(" final inline threshold = {}", threshold); // FIXME: Give a bonus to functions with only a single caller let mut first_block = true; let mut cost = 0; // Traverse the MIR manually so we can account for the effects of // inlining on the CFG. let mut work_list = vec![START_BLOCK]; let mut visited = BitSet::new_empty(callee_body.basic_blocks().len()); while let Some(bb) = work_list.pop() { if !visited.insert(bb.index()) { continue; } let blk = &callee_body.basic_blocks()[bb]; for stmt in &blk.statements { // Don't count StorageLive/StorageDead in the inlining cost. match stmt.kind { StatementKind::StorageLive(_) | StatementKind::StorageDead(_) | StatementKind::Nop => {} _ => cost += INSTR_COST, } } let term = blk.terminator(); let mut is_drop = false; match term.kind { TerminatorKind::Drop { ref place, target, unwind } | TerminatorKind::DropAndReplace { ref place, target, unwind, .. } => { is_drop = true; work_list.push(target); // If the place doesn't actually need dropping, treat it like // a regular goto. let ty = callsite.callee.subst_mir(self.tcx, &place.ty(callee_body, tcx).ty); if ty.needs_drop(tcx, self.param_env) { cost += CALL_PENALTY; if let Some(unwind) = unwind { cost += LANDINGPAD_PENALTY; work_list.push(unwind); } } else { cost += INSTR_COST; } } TerminatorKind::Unreachable | TerminatorKind::Call { destination: None, .. } if first_block => { // If the function always diverges, don't inline // unless the cost is zero threshold = 0; } TerminatorKind::Call { func: Operand::Constant(ref f), cleanup, .. } => { if let ty::FnDef(def_id, substs) = *callsite.callee.subst_mir(self.tcx, &f.literal.ty()).kind() { let substs = self.tcx.normalize_erasing_regions(self.param_env, substs); if let Ok(Some(instance)) = Instance::resolve(self.tcx, self.param_env, def_id, substs) { if callsite.callee.def_id() == instance.def_id() { return Err("self-recursion"); } else if self.history.contains(&instance) { return Err("already inlined"); } } // Don't give intrinsics the extra penalty for calls let f = tcx.fn_sig(def_id); if f.abi() == Abi::RustIntrinsic || f.abi() == Abi::PlatformIntrinsic { cost += INSTR_COST; } else { cost += CALL_PENALTY; } } else { cost += CALL_PENALTY; } if cleanup.is_some() { cost += LANDINGPAD_PENALTY; } } TerminatorKind::Assert { cleanup, .. } => { cost += CALL_PENALTY; if cleanup.is_some() { cost += LANDINGPAD_PENALTY; } } TerminatorKind::Resume => cost += RESUME_PENALTY, TerminatorKind::InlineAsm { cleanup, .. } => { cost += INSTR_COST; if cleanup.is_some() { cost += LANDINGPAD_PENALTY; } } _ => cost += INSTR_COST, } if !is_drop { for &succ in term.successors() { work_list.push(succ); } } first_block = false; } // Count up the cost of local variables and temps, if we know the size // use that, otherwise we use a moderately-large dummy cost. let ptr_size = tcx.data_layout.pointer_size.bytes(); for v in callee_body.vars_and_temps_iter() { let ty = callsite.callee.subst_mir(self.tcx, &callee_body.local_decls[v].ty); // Cost of the var is the size in machine-words, if we know // it. if let Some(size) = type_size_of(tcx, self.param_env, ty) { cost += ((size + ptr_size - 1) / ptr_size) as usize; } else { cost += UNKNOWN_SIZE_COST; } } if let InlineAttr::Always = callee_attrs.inline { debug!("INLINING {:?} because inline(always) [cost={}]", callsite, cost); Ok(()) } else { if cost <= threshold { debug!("INLINING {:?} [cost={} <= threshold={}]", callsite, cost, threshold); Ok(()) } else { debug!("NOT inlining {:?} [cost={} > threshold={}]", callsite, cost, threshold); Err("cost above threshold") } } } fn inline_call( &self, caller_body: &mut Body<'tcx>, callsite: &CallSite<'tcx>, mut callee_body: Body<'tcx>, ) { let terminator = caller_body[callsite.block].terminator.take().unwrap(); match terminator.kind { TerminatorKind::Call { args, destination, cleanup, .. } => { // If the call is something like `a[*i] = f(i)`, where // `i : &mut usize`, then just duplicating the `a[*i]` // Place could result in two different locations if `f` // writes to `i`. To prevent this we need to create a temporary // borrow of the place and pass the destination as `*temp` instead. fn dest_needs_borrow(place: Place<'_>) -> bool { for elem in place.projection.iter() { match elem { ProjectionElem::Deref | ProjectionElem::Index(_) => return true, _ => {} } } false } let dest = if let Some((destination_place, _)) = destination { if dest_needs_borrow(destination_place) { trace!("creating temp for return destination"); let dest = Rvalue::Ref( self.tcx.lifetimes.re_erased, BorrowKind::Mut { allow_two_phase_borrow: false }, destination_place, ); let dest_ty = dest.ty(caller_body, self.tcx); let temp = Place::from(self.new_call_temp(caller_body, &callsite, dest_ty)); caller_body[callsite.block].statements.push(Statement { source_info: callsite.source_info, kind: StatementKind::Assign(Box::new((temp, dest))), }); self.tcx.mk_place_deref(temp) } else { destination_place } } else { trace!("creating temp for return place"); Place::from(self.new_call_temp(caller_body, &callsite, callee_body.return_ty())) }; // Copy the arguments if needed. let args: Vec<_> = self.make_call_args(args, &callsite, caller_body, &callee_body); let mut expn_data = ExpnData::default( ExpnKind::Inlined, callsite.source_info.span, self.tcx.sess.edition(), None, None, ); expn_data.def_site = callee_body.span; let expn_data = LocalExpnId::fresh(expn_data, self.tcx.create_stable_hashing_context()); let mut integrator = Integrator { args: &args, new_locals: Local::new(caller_body.local_decls.len()).., new_scopes: SourceScope::new(caller_body.source_scopes.len()).., new_blocks: BasicBlock::new(caller_body.basic_blocks().len()).., destination: dest, return_block: callsite.target, cleanup_block: cleanup, in_cleanup_block: false, tcx: self.tcx, expn_data, always_live_locals: BitSet::new_filled(callee_body.local_decls.len()), }; // Map all `Local`s, `SourceScope`s and `BasicBlock`s to new ones // (or existing ones, in a few special cases) in the caller. integrator.visit_body(&mut callee_body); for scope in &mut callee_body.source_scopes { // FIXME(eddyb) move this into a `fn visit_scope_data` in `Integrator`. if scope.parent_scope.is_none() { let callsite_scope = &caller_body.source_scopes[callsite.source_info.scope]; // Attach the outermost callee scope as a child of the callsite // scope, via the `parent_scope` and `inlined_parent_scope` chains. scope.parent_scope = Some(callsite.source_info.scope); assert_eq!(scope.inlined_parent_scope, None); scope.inlined_parent_scope = if callsite_scope.inlined.is_some() { Some(callsite.source_info.scope) } else { callsite_scope.inlined_parent_scope }; // Mark the outermost callee scope as an inlined one. assert_eq!(scope.inlined, None); scope.inlined = Some((callsite.callee, callsite.source_info.span)); } else if scope.inlined_parent_scope.is_none() { // Make it easy to find the scope with `inlined` set above. scope.inlined_parent_scope = Some(integrator.map_scope(OUTERMOST_SOURCE_SCOPE)); } } // If there are any locals without storage markers, give them storage only for the // duration of the call. for local in callee_body.vars_and_temps_iter() { if integrator.always_live_locals.contains(local) { let new_local = integrator.map_local(local); caller_body[callsite.block].statements.push(Statement { source_info: callsite.source_info, kind: StatementKind::StorageLive(new_local), }); } } if let Some(block) = callsite.target { // To avoid repeated O(n) insert, push any new statements to the end and rotate // the slice once. let mut n = 0; for local in callee_body.vars_and_temps_iter().rev() { if integrator.always_live_locals.contains(local) { let new_local = integrator.map_local(local); caller_body[block].statements.push(Statement { source_info: callsite.source_info, kind: StatementKind::StorageDead(new_local), }); n += 1; } } caller_body[block].statements.rotate_right(n); } // Insert all of the (mapped) parts of the callee body into the caller. caller_body.local_decls.extend(callee_body.drain_vars_and_temps()); caller_body.source_scopes.extend(&mut callee_body.source_scopes.drain(..)); caller_body.var_debug_info.append(&mut callee_body.var_debug_info); caller_body.basic_blocks_mut().extend(callee_body.basic_blocks_mut().drain(..)); caller_body[callsite.block].terminator = Some(Terminator { source_info: callsite.source_info, kind: TerminatorKind::Goto { target: integrator.map_block(START_BLOCK) }, }); // Copy only unevaluated constants from the callee_body into the caller_body. // Although we are only pushing `ConstKind::Unevaluated` consts to // `required_consts`, here we may not only have `ConstKind::Unevaluated` // because we are calling `subst_and_normalize_erasing_regions`. caller_body.required_consts.extend( callee_body.required_consts.iter().copied().filter(|&ct| { match ct.literal.const_for_ty() { Some(ct) => matches!(ct.val(), ConstKind::Unevaluated(_)), None => true, } }), ); } kind => bug!("unexpected terminator kind {:?}", kind), } } fn make_call_args( &self, args: Vec>, callsite: &CallSite<'tcx>, caller_body: &mut Body<'tcx>, callee_body: &Body<'tcx>, ) -> Vec { let tcx = self.tcx; // There is a bit of a mismatch between the *caller* of a closure and the *callee*. // The caller provides the arguments wrapped up in a tuple: // // tuple_tmp = (a, b, c) // Fn::call(closure_ref, tuple_tmp) // // meanwhile the closure body expects the arguments (here, `a`, `b`, and `c`) // as distinct arguments. (This is the "rust-call" ABI hack.) Normally, codegen has // the job of unpacking this tuple. But here, we are codegen. =) So we want to create // a vector like // // [closure_ref, tuple_tmp.0, tuple_tmp.1, tuple_tmp.2] // // Except for one tiny wrinkle: we don't actually want `tuple_tmp.0`. It's more convenient // if we "spill" that into *another* temporary, so that we can map the argument // variable in the callee MIR directly to an argument variable on our side. // So we introduce temporaries like: // // tmp0 = tuple_tmp.0 // tmp1 = tuple_tmp.1 // tmp2 = tuple_tmp.2 // // and the vector is `[closure_ref, tmp0, tmp1, tmp2]`. if callsite.fn_sig.abi() == Abi::RustCall && callee_body.spread_arg.is_none() { let mut args = args.into_iter(); let self_ = self.create_temp_if_necessary(args.next().unwrap(), callsite, caller_body); let tuple = self.create_temp_if_necessary(args.next().unwrap(), callsite, caller_body); assert!(args.next().is_none()); let tuple = Place::from(tuple); let ty::Tuple(tuple_tys) = tuple.ty(caller_body, tcx).ty.kind() else { bug!("Closure arguments are not passed as a tuple"); }; // The `closure_ref` in our example above. let closure_ref_arg = iter::once(self_); // The `tmp0`, `tmp1`, and `tmp2` in our example above. let tuple_tmp_args = tuple_tys.iter().enumerate().map(|(i, ty)| { // This is e.g., `tuple_tmp.0` in our example above. let tuple_field = Operand::Move(tcx.mk_place_field(tuple, Field::new(i), ty)); // Spill to a local to make e.g., `tmp0`. self.create_temp_if_necessary(tuple_field, callsite, caller_body) }); closure_ref_arg.chain(tuple_tmp_args).collect() } else { args.into_iter() .map(|a| self.create_temp_if_necessary(a, callsite, caller_body)) .collect() } } /// If `arg` is already a temporary, returns it. Otherwise, introduces a fresh /// temporary `T` and an instruction `T = arg`, and returns `T`. fn create_temp_if_necessary( &self, arg: Operand<'tcx>, callsite: &CallSite<'tcx>, caller_body: &mut Body<'tcx>, ) -> Local { // Reuse the operand if it is a moved temporary. if let Operand::Move(place) = &arg && let Some(local) = place.as_local() && caller_body.local_kind(local) == LocalKind::Temp { return local; } // Otherwise, create a temporary for the argument. trace!("creating temp for argument {:?}", arg); let arg_ty = arg.ty(caller_body, self.tcx); let local = self.new_call_temp(caller_body, callsite, arg_ty); caller_body[callsite.block].statements.push(Statement { source_info: callsite.source_info, kind: StatementKind::Assign(Box::new((Place::from(local), Rvalue::Use(arg)))), }); local } /// Introduces a new temporary into the caller body that is live for the duration of the call. fn new_call_temp( &self, caller_body: &mut Body<'tcx>, callsite: &CallSite<'tcx>, ty: Ty<'tcx>, ) -> Local { let local = caller_body.local_decls.push(LocalDecl::new(ty, callsite.source_info.span)); caller_body[callsite.block].statements.push(Statement { source_info: callsite.source_info, kind: StatementKind::StorageLive(local), }); if let Some(block) = callsite.target { caller_body[block].statements.insert( 0, Statement { source_info: callsite.source_info, kind: StatementKind::StorageDead(local), }, ); } local } } fn type_size_of<'tcx>( tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>, ty: Ty<'tcx>, ) -> Option { tcx.layout_of(param_env.and(ty)).ok().map(|layout| layout.size.bytes()) } /** * Integrator. * * Integrates blocks from the callee function into the calling function. * Updates block indices, references to locals and other control flow * stuff. */ struct Integrator<'a, 'tcx> { args: &'a [Local], new_locals: RangeFrom, new_scopes: RangeFrom, new_blocks: RangeFrom, destination: Place<'tcx>, return_block: Option, cleanup_block: Option, in_cleanup_block: bool, tcx: TyCtxt<'tcx>, expn_data: LocalExpnId, always_live_locals: BitSet, } impl Integrator<'_, '_> { fn map_local(&self, local: Local) -> Local { let new = if local == RETURN_PLACE { self.destination.local } else { let idx = local.index() - 1; if idx < self.args.len() { self.args[idx] } else { Local::new(self.new_locals.start.index() + (idx - self.args.len())) } }; trace!("mapping local `{:?}` to `{:?}`", local, new); new } fn map_scope(&self, scope: SourceScope) -> SourceScope { let new = SourceScope::new(self.new_scopes.start.index() + scope.index()); trace!("mapping scope `{:?}` to `{:?}`", scope, new); new } fn map_block(&self, block: BasicBlock) -> BasicBlock { let new = BasicBlock::new(self.new_blocks.start.index() + block.index()); trace!("mapping block `{:?}` to `{:?}`", block, new); new } } impl<'tcx> MutVisitor<'tcx> for Integrator<'_, 'tcx> { fn tcx(&self) -> TyCtxt<'tcx> { self.tcx } fn visit_local(&mut self, local: &mut Local, _ctxt: PlaceContext, _location: Location) { *local = self.map_local(*local); } fn visit_source_scope(&mut self, scope: &mut SourceScope) { *scope = self.map_scope(*scope); } fn visit_span(&mut self, span: &mut Span) { // Make sure that all spans track the fact that they were inlined. *span = span.fresh_expansion(self.expn_data); } fn visit_place(&mut self, place: &mut Place<'tcx>, context: PlaceContext, location: Location) { for elem in place.projection { // FIXME: Make sure that return place is not used in an indexing projection, since it // won't be rebased as it is supposed to be. assert_ne!(ProjectionElem::Index(RETURN_PLACE), elem); } // If this is the `RETURN_PLACE`, we need to rebase any projections onto it. let dest_proj_len = self.destination.projection.len(); if place.local == RETURN_PLACE && dest_proj_len > 0 { let mut projs = Vec::with_capacity(dest_proj_len + place.projection.len()); projs.extend(self.destination.projection); projs.extend(place.projection); place.projection = self.tcx.intern_place_elems(&*projs); } // Handles integrating any locals that occur in the base // or projections self.super_place(place, context, location) } fn visit_basic_block_data(&mut self, block: BasicBlock, data: &mut BasicBlockData<'tcx>) { self.in_cleanup_block = data.is_cleanup; self.super_basic_block_data(block, data); self.in_cleanup_block = false; } fn visit_retag(&mut self, kind: &mut RetagKind, place: &mut Place<'tcx>, loc: Location) { self.super_retag(kind, place, loc); // We have to patch all inlined retags to be aware that they are no longer // happening on function entry. if *kind == RetagKind::FnEntry { *kind = RetagKind::Default; } } fn visit_statement(&mut self, statement: &mut Statement<'tcx>, location: Location) { if let StatementKind::StorageLive(local) | StatementKind::StorageDead(local) = statement.kind { self.always_live_locals.remove(local); } self.super_statement(statement, location); } fn visit_terminator(&mut self, terminator: &mut Terminator<'tcx>, loc: Location) { // Don't try to modify the implicit `_0` access on return (`return` terminators are // replaced down below anyways). if !matches!(terminator.kind, TerminatorKind::Return) { self.super_terminator(terminator, loc); } match terminator.kind { TerminatorKind::GeneratorDrop | TerminatorKind::Yield { .. } => bug!(), TerminatorKind::Goto { ref mut target } => { *target = self.map_block(*target); } TerminatorKind::SwitchInt { ref mut targets, .. } => { for tgt in targets.all_targets_mut() { *tgt = self.map_block(*tgt); } } TerminatorKind::Drop { ref mut target, ref mut unwind, .. } | TerminatorKind::DropAndReplace { ref mut target, ref mut unwind, .. } => { *target = self.map_block(*target); if let Some(tgt) = *unwind { *unwind = Some(self.map_block(tgt)); } else if !self.in_cleanup_block { // Unless this drop is in a cleanup block, add an unwind edge to // the original call's cleanup block *unwind = self.cleanup_block; } } TerminatorKind::Call { ref mut destination, ref mut cleanup, .. } => { if let Some((_, ref mut tgt)) = *destination { *tgt = self.map_block(*tgt); } if let Some(tgt) = *cleanup { *cleanup = Some(self.map_block(tgt)); } else if !self.in_cleanup_block { // Unless this call is in a cleanup block, add an unwind edge to // the original call's cleanup block *cleanup = self.cleanup_block; } } TerminatorKind::Assert { ref mut target, ref mut cleanup, .. } => { *target = self.map_block(*target); if let Some(tgt) = *cleanup { *cleanup = Some(self.map_block(tgt)); } else if !self.in_cleanup_block { // Unless this assert is in a cleanup block, add an unwind edge to // the original call's cleanup block *cleanup = self.cleanup_block; } } TerminatorKind::Return => { terminator.kind = if let Some(tgt) = self.return_block { TerminatorKind::Goto { target: tgt } } else { TerminatorKind::Unreachable } } TerminatorKind::Resume => { if let Some(tgt) = self.cleanup_block { terminator.kind = TerminatorKind::Goto { target: tgt } } } TerminatorKind::Abort => {} TerminatorKind::Unreachable => {} TerminatorKind::FalseEdge { ref mut real_target, ref mut imaginary_target } => { *real_target = self.map_block(*real_target); *imaginary_target = self.map_block(*imaginary_target); } TerminatorKind::FalseUnwind { real_target: _, unwind: _ } => // see the ordering of passes in the optimized_mir query. { bug!("False unwinds should have been removed before inlining") } TerminatorKind::InlineAsm { ref mut destination, ref mut cleanup, .. } => { if let Some(ref mut tgt) = *destination { *tgt = self.map_block(*tgt); } else if !self.in_cleanup_block { // Unless this inline asm is in a cleanup block, add an unwind edge to // the original call's cleanup block *cleanup = self.cleanup_block; } } } } }