| //! Inlining pass for MIR functions. |
| |
| use std::iter; |
| use std::ops::{Range, RangeFrom}; |
| |
| use rustc_attr::InlineAttr; |
| use rustc_hir::def::DefKind; |
| use rustc_hir::def_id::DefId; |
| use rustc_index::Idx; |
| use rustc_index::bit_set::BitSet; |
| use rustc_middle::bug; |
| use rustc_middle::middle::codegen_fn_attrs::{CodegenFnAttrFlags, CodegenFnAttrs}; |
| use rustc_middle::mir::visit::*; |
| use rustc_middle::mir::*; |
| use rustc_middle::ty::{ |
| self, Instance, InstanceKind, ParamEnv, Ty, TyCtxt, TypeFlags, TypeVisitableExt, |
| }; |
| use rustc_session::config::{DebugInfo, OptLevel}; |
| use rustc_span::source_map::Spanned; |
| use rustc_span::sym; |
| use rustc_target::abi::FieldIdx; |
| use rustc_target::spec::abi::Abi; |
| use tracing::{debug, instrument, trace, trace_span}; |
| |
| use crate::cost_checker::CostChecker; |
| use crate::deref_separator::deref_finder; |
| use crate::simplify::simplify_cfg; |
| use crate::util; |
| use crate::validate::validate_types; |
| |
| pub(crate) mod cycle; |
| |
| const TOP_DOWN_DEPTH_LIMIT: usize = 5; |
| |
| // Made public so that `mir_drops_elaborated_and_const_checked` can be overridden |
| // by custom rustc drivers, running all the steps by themselves. See #114628. |
| pub struct Inline; |
| |
| #[derive(Clone, Debug)] |
| struct CallSite<'tcx> { |
| callee: Instance<'tcx>, |
| fn_sig: ty::PolyFnSig<'tcx>, |
| block: BasicBlock, |
| source_info: SourceInfo, |
| } |
| |
| impl<'tcx> crate::MirPass<'tcx> for Inline { |
| fn is_enabled(&self, sess: &rustc_session::Session) -> bool { |
| // FIXME(#127234): Coverage instrumentation currently doesn't handle inlined |
| // MIR correctly when Modified Condition/Decision Coverage is enabled. |
| if sess.instrument_coverage_mcdc() { |
| return false; |
| } |
| |
| if let Some(enabled) = sess.opts.unstable_opts.inline_mir { |
| return enabled; |
| } |
| |
| match sess.mir_opt_level() { |
| 0 | 1 => false, |
| 2 => { |
| (sess.opts.optimize == OptLevel::Default |
| || sess.opts.optimize == OptLevel::Aggressive) |
| && sess.opts.incremental == None |
| } |
| _ => true, |
| } |
| } |
| |
| 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); |
| simplify_cfg(body); |
| deref_finder(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 coroutines, 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.coroutine.is_some() { |
| return false; |
| } |
| |
| let param_env = tcx.param_env_reveal_all_normalized(def_id); |
| let codegen_fn_attrs = tcx.codegen_fn_attrs(def_id); |
| |
| let mut this = Inliner { |
| tcx, |
| param_env, |
| codegen_fn_attrs, |
| history: Vec::new(), |
| changed: false, |
| caller_is_inline_forwarder: matches!( |
| codegen_fn_attrs.inline, |
| InlineAttr::Hint | InlineAttr::Always |
| ) && body_is_forwarder(body), |
| }; |
| let blocks = START_BLOCK..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, |
| /// Stack of inlined instances. |
| /// We only check the `DefId` and not the args because we want to |
| /// avoid inlining cases of polymorphic recursion. |
| /// The number of `DefId`s is finite, so checking history is enough |
| /// to ensure that we do not loop endlessly while inlining. |
| history: Vec<DefId>, |
| /// Indicates that the caller body has been modified. |
| changed: bool, |
| /// Indicates that the caller is #[inline] and just calls another function, |
| /// and thus we can inline less into it as it'll be inlined itself. |
| caller_is_inline_forwarder: bool, |
| } |
| |
| impl<'tcx> Inliner<'tcx> { |
| fn process_blocks(&mut self, caller_body: &mut Body<'tcx>, blocks: Range<BasicBlock>) { |
| // How many callsites in this body are we allowed to inline? We need to limit this in order |
| // to prevent super-linear growth in MIR size |
| let inline_limit = match self.history.len() { |
| 0 => usize::MAX, |
| 1..=TOP_DOWN_DEPTH_LIMIT => 1, |
| _ => return, |
| }; |
| let mut inlined_count = 0; |
| 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); |
| } |
| Ok(new_blocks) => { |
| debug!("inlined {}", callsite.callee); |
| self.changed = true; |
| |
| self.history.push(callsite.callee.def_id()); |
| self.process_blocks(caller_body, new_blocks); |
| self.history.pop(); |
| |
| inlined_count += 1; |
| if inlined_count == inline_limit { |
| debug!("inline count reached"); |
| return; |
| } |
| } |
| } |
| } |
| } |
| |
| /// 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<std::ops::Range<BasicBlock>, &'static str> { |
| self.check_mir_is_available(caller_body, callsite.callee)?; |
| |
| let callee_attrs = self.tcx.codegen_fn_attrs(callsite.callee.def_id()); |
| let cross_crate_inlinable = self.tcx.cross_crate_inlinable(callsite.callee.def_id()); |
| self.check_codegen_attributes(callsite, callee_attrs, cross_crate_inlinable)?; |
| |
| // Intrinsic fallback bodies are automatically made cross-crate inlineable, |
| // but at this stage we don't know whether codegen knows the intrinsic, |
| // so just conservatively don't inline it. |
| if self.tcx.has_attr(callsite.callee.def_id(), sym::rustc_intrinsic) { |
| return Err("Callee is an intrinsic, do not inline fallback bodies"); |
| } |
| |
| let terminator = caller_body[callsite.block].terminator.as_ref().unwrap(); |
| let TerminatorKind::Call { args, destination, .. } = &terminator.kind else { bug!() }; |
| let destination_ty = destination.ty(&caller_body.local_decls, self.tcx).ty; |
| for arg in args { |
| if !arg.node.ty(&caller_body.local_decls, self.tcx).is_sized(self.tcx, self.param_env) { |
| // We do not allow inlining functions with unsized params. Inlining these functions |
| // could create unsized locals, which are unsound and being phased out. |
| return Err("Call has unsized argument"); |
| } |
| } |
| |
| let callee_body = try_instance_mir(self.tcx, callsite.callee.def)?; |
| self.check_mir_body(callsite, callee_body, callee_attrs, cross_crate_inlinable)?; |
| |
| if !self.tcx.consider_optimizing(|| { |
| format!("Inline {:?} into {:?}", callsite.callee, caller_body.source) |
| }) { |
| return Err("optimization fuel exhausted"); |
| } |
| |
| let Ok(callee_body) = callsite.callee.try_instantiate_mir_and_normalize_erasing_regions( |
| self.tcx, |
| self.param_env, |
| ty::EarlyBinder::bind(callee_body.clone()), |
| ) else { |
| return Err("failed to normalize callee body"); |
| }; |
| |
| // Normally, this shouldn't be required, but trait normalization failure can create a |
| // validation ICE. |
| if !validate_types( |
| self.tcx, |
| MirPhase::Runtime(RuntimePhase::Optimized), |
| self.param_env, |
| &callee_body, |
| &caller_body, |
| ) |
| .is_empty() |
| { |
| return Err("failed to validate callee body"); |
| } |
| |
| // Check call signature compatibility. |
| // Normally, this shouldn't be required, but trait normalization failure can create a |
| // validation ICE. |
| let output_type = callee_body.return_ty(); |
| if !util::relate_types(self.tcx, self.param_env, ty::Covariant, output_type, destination_ty) |
| { |
| trace!(?output_type, ?destination_ty); |
| return Err("failed to normalize return type"); |
| } |
| if callsite.fn_sig.abi() == Abi::RustCall { |
| // FIXME: Don't inline user-written `extern "rust-call"` functions, |
| // since this is generally perf-negative on rustc, and we hope that |
| // LLVM will inline these functions instead. |
| if callee_body.spread_arg.is_some() { |
| return Err("do not inline user-written rust-call functions"); |
| } |
| |
| let (self_arg, arg_tuple) = match &args[..] { |
| [arg_tuple] => (None, arg_tuple), |
| [self_arg, arg_tuple] => (Some(self_arg), arg_tuple), |
| _ => bug!("Expected `rust-call` to have 1 or 2 args"), |
| }; |
| |
| let self_arg_ty = |
| self_arg.map(|self_arg| self_arg.node.ty(&caller_body.local_decls, self.tcx)); |
| |
| let arg_tuple_ty = arg_tuple.node.ty(&caller_body.local_decls, self.tcx); |
| let ty::Tuple(arg_tuple_tys) = *arg_tuple_ty.kind() else { |
| bug!("Closure arguments are not passed as a tuple"); |
| }; |
| |
| for (arg_ty, input) in |
| self_arg_ty.into_iter().chain(arg_tuple_tys).zip(callee_body.args_iter()) |
| { |
| let input_type = callee_body.local_decls[input].ty; |
| if !util::relate_types(self.tcx, self.param_env, ty::Covariant, input_type, arg_ty) |
| { |
| trace!(?arg_ty, ?input_type); |
| return Err("failed to normalize tuple argument type"); |
| } |
| } |
| } else { |
| for (arg, input) in args.iter().zip(callee_body.args_iter()) { |
| let input_type = callee_body.local_decls[input].ty; |
| let arg_ty = arg.node.ty(&caller_body.local_decls, self.tcx); |
| if !util::relate_types(self.tcx, self.param_env, ty::Covariant, input_type, arg_ty) |
| { |
| trace!(?arg_ty, ?input_type); |
| return Err("failed to normalize argument type"); |
| } |
| } |
| } |
| |
| 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> { |
| let caller_def_id = caller_body.source.def_id(); |
| let callee_def_id = callee.def_id(); |
| if callee_def_id == caller_def_id { |
| return Err("self-recursion"); |
| } |
| |
| match callee.def { |
| InstanceKind::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. |
| InstanceKind::Intrinsic(_) | InstanceKind::Virtual(..) => { |
| return Err("instance without MIR (intrinsic / virtual)"); |
| } |
| |
| // FIXME(#127030): `ConstParamHasTy` has bad interactions with |
| // the drop shim builder, which does not evaluate predicates in |
| // the correct param-env for types being dropped. Stall resolving |
| // the MIR for this instance until all of its const params are |
| // substituted. |
| InstanceKind::DropGlue(_, Some(ty)) if ty.has_type_flags(TypeFlags::HAS_CT_PARAM) => { |
| return Err("still needs substitution"); |
| } |
| |
| // 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. |
| InstanceKind::VTableShim(_) |
| | InstanceKind::ReifyShim(..) |
| | InstanceKind::FnPtrShim(..) |
| | InstanceKind::ClosureOnceShim { .. } |
| | InstanceKind::ConstructCoroutineInClosureShim { .. } |
| | InstanceKind::DropGlue(..) |
| | InstanceKind::CloneShim(..) |
| | InstanceKind::ThreadLocalShim(..) |
| | InstanceKind::FnPtrAddrShim(..) |
| | InstanceKind::AsyncDropGlueCtorShim(..) => 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 callee_def_id.is_local() { |
| // 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_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<CallSite<'tcx>> { |
| // Only consider direct calls to functions |
| let terminator = bb_data.terminator(); |
| |
| // FIXME(explicit_tail_calls): figure out if we can inline tail calls |
| if let TerminatorKind::Call { ref func, fn_span, .. } = terminator.kind { |
| let func_ty = func.ty(caller_body, self.tcx); |
| if let ty::FnDef(def_id, args) = *func_ty.kind() { |
| // To resolve an instance its args have to be fully normalized. |
| let args = self.tcx.try_normalize_erasing_regions(self.param_env, args).ok()?; |
| let callee = |
| Instance::try_resolve(self.tcx, self.param_env, def_id, args).ok().flatten()?; |
| |
| if let InstanceKind::Virtual(..) | InstanceKind::Intrinsic(_) = callee.def { |
| return None; |
| } |
| |
| if self.history.contains(&callee.def_id()) { |
| return None; |
| } |
| |
| let fn_sig = self.tcx.fn_sig(def_id).instantiate(self.tcx, args); |
| |
| // Additionally, check that the body that we're inlining actually agrees |
| // with the ABI of the trait that the item comes from. |
| if let InstanceKind::Item(instance_def_id) = callee.def |
| && self.tcx.def_kind(instance_def_id) == DefKind::AssocFn |
| && let instance_fn_sig = self.tcx.fn_sig(instance_def_id).skip_binder() |
| && instance_fn_sig.abi() != fn_sig.abi() |
| { |
| return None; |
| } |
| |
| let source_info = SourceInfo { span: fn_span, ..terminator.source_info }; |
| |
| return Some(CallSite { callee, fn_sig, block: bb, 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, |
| cross_crate_inlinable: bool, |
| ) -> Result<(), &'static str> { |
| if self.tcx.has_attr(callsite.callee.def_id(), sym::rustc_no_mir_inline) { |
| return Err("#[rustc_no_mir_inline]"); |
| } |
| |
| if let InlineAttr::Never = callee_attrs.inline { |
| return Err("never inline hint"); |
| } |
| |
| // Reachability pass defines which functions are eligible for inlining. Generally inlining |
| // other functions is incorrect because they could reference symbols that aren't exported. |
| let is_generic = callsite |
| .callee |
| .args |
| .non_erasable_generics(self.tcx, callsite.callee.def_id()) |
| .next() |
| .is_some(); |
| if !is_generic && !cross_crate_inlinable { |
| return Err("not exported"); |
| } |
| |
| if callsite.fn_sig.c_variadic() { |
| return Err("C variadic"); |
| } |
| |
| 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"); |
| } |
| |
| // Two functions are compatible if the callee has no attribute (meaning |
| // that it's codegen agnostic), or sets an attribute that is identical |
| // to this function's attribute. |
| if callee_attrs.instruction_set.is_some() |
| && callee_attrs.instruction_set != self.codegen_fn_attrs.instruction_set |
| { |
| return Err("incompatible instruction set"); |
| } |
| |
| let callee_feature_names = callee_attrs.target_features.iter().map(|f| f.name); |
| let this_feature_names = self.codegen_fn_attrs.target_features.iter().map(|f| f.name); |
| if callee_feature_names.ne(this_feature_names) { |
| // In general it is not correct to inline a callee with target features that are a |
| // subset of the caller. This is because the callee might contain calls, and the ABI of |
| // those calls depends on the target features of the surrounding function. By moving a |
| // `Call` terminator from one MIR body to another with more target features, we might |
| // change the ABI of that call! |
| return Err("incompatible target features"); |
| } |
| |
| 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, |
| cross_crate_inlinable: bool, |
| ) -> Result<(), &'static str> { |
| let tcx = self.tcx; |
| |
| if let Some(_) = callee_body.tainted_by_errors { |
| return Err("Body is tainted"); |
| } |
| |
| let mut threshold = if self.caller_is_inline_forwarder { |
| self.tcx.sess.opts.unstable_opts.inline_mir_forwarder_threshold.unwrap_or(30) |
| } else if cross_crate_inlinable { |
| self.tcx.sess.opts.unstable_opts.inline_mir_hint_threshold.unwrap_or(100) |
| } else { |
| self.tcx.sess.opts.unstable_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 checker = |
| CostChecker::new(self.tcx, self.param_env, Some(callsite.callee), callee_body); |
| |
| checker.add_function_level_costs(); |
| |
| // 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]; |
| checker.visit_basic_block_data(bb, blk); |
| |
| let term = blk.terminator(); |
| if let TerminatorKind::Drop { ref place, target, unwind, replace: _ } = term.kind { |
| work_list.push(target); |
| |
| // If the place doesn't actually need dropping, treat it like a regular goto. |
| let ty = callsite.callee.instantiate_mir( |
| self.tcx, |
| ty::EarlyBinder::bind(&place.ty(callee_body, tcx).ty), |
| ); |
| if ty.needs_drop(tcx, self.param_env) |
| && let UnwindAction::Cleanup(unwind) = unwind |
| { |
| work_list.push(unwind); |
| } |
| } else if callee_attrs.instruction_set != self.codegen_fn_attrs.instruction_set |
| && matches!(term.kind, TerminatorKind::InlineAsm { .. }) |
| { |
| // During the attribute checking stage we allow a callee with no |
| // instruction_set assigned to count as compatible with a function that does |
| // assign one. However, during this stage we require an exact match when any |
| // inline-asm is detected. LLVM will still possibly do an inline later on |
| // if the no-attribute function ends up with the same instruction set anyway. |
| return Err("Cannot move inline-asm across instruction sets"); |
| } else if let TerminatorKind::TailCall { .. } = term.kind { |
| // FIXME(explicit_tail_calls): figure out how exactly functions containing tail |
| // calls can be inlined (and if they even should) |
| return Err("can't inline functions with tail calls"); |
| } else { |
| work_list.extend(term.successors()) |
| } |
| } |
| |
| // N.B. We still apply our cost threshold to #[inline(always)] functions. |
| // That attribute is often applied to very large functions that exceed LLVM's (very |
| // generous) inlining threshold. Such functions are very poor MIR inlining candidates. |
| // Always inlining #[inline(always)] functions in MIR, on net, slows down the compiler. |
| let cost = checker.cost(); |
| 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(); |
| let TerminatorKind::Call { func, args, destination, unwind, target, .. } = terminator.kind |
| else { |
| bug!("unexpected terminator kind {:?}", terminator.kind); |
| }; |
| |
| let return_block = if let Some(block) = target { |
| // Prepare a new block for code that should execute when call returns. We don't use |
| // target block directly since it might have other predecessors. |
| let mut data = BasicBlockData::new(Some(Terminator { |
| source_info: terminator.source_info, |
| kind: TerminatorKind::Goto { target: block }, |
| })); |
| data.is_cleanup = caller_body[block].is_cleanup; |
| Some(caller_body.basic_blocks_mut().push(data)) |
| } else { |
| None |
| }; |
| |
| // 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 dest_needs_borrow(destination) { |
| trace!("creating temp for return destination"); |
| let dest = Rvalue::Ref( |
| self.tcx.lifetimes.re_erased, |
| BorrowKind::Mut { kind: MutBorrowKind::Default }, |
| destination, |
| ); |
| let dest_ty = dest.ty(caller_body, self.tcx); |
| let temp = |
| Place::from(self.new_call_temp(caller_body, callsite, dest_ty, return_block)); |
| 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 |
| }; |
| |
| // Always create a local to hold the destination, as `RETURN_PLACE` may appear |
| // where a full `Place` is not allowed. |
| let (remap_destination, destination_local) = if let Some(d) = dest.as_local() { |
| (false, d) |
| } else { |
| ( |
| true, |
| self.new_call_temp( |
| caller_body, |
| callsite, |
| destination.ty(caller_body, self.tcx).ty, |
| return_block, |
| ), |
| ) |
| }; |
| |
| // Copy the arguments if needed. |
| let args = self.make_call_args(args, callsite, caller_body, &callee_body, return_block); |
| |
| 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: destination_local, |
| callsite_scope: caller_body.source_scopes[callsite.source_info.scope].clone(), |
| callsite, |
| cleanup_block: unwind, |
| in_cleanup_block: false, |
| return_block, |
| tcx: self.tcx, |
| 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); |
| |
| // 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) = return_block { |
| // To avoid repeated O(n) insert, push any new statements to the end and rotate |
| // the slice once. |
| let mut n = 0; |
| if remap_destination { |
| caller_body[block].statements.push(Statement { |
| source_info: callsite.source_info, |
| kind: StatementKind::Assign(Box::new(( |
| dest, |
| Rvalue::Use(Operand::Move(destination_local.into())), |
| ))), |
| }); |
| n += 1; |
| } |
| 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.append(&mut callee_body.source_scopes); |
| if self |
| .tcx |
| .sess |
| .opts |
| .unstable_opts |
| .inline_mir_preserve_debug |
| .unwrap_or(self.tcx.sess.opts.debuginfo != DebugInfo::None) |
| { |
| // Note that we need to preserve these in the standard library so that |
| // people working on rust can build with or without debuginfo while |
| // still getting consistent results from the mir-opt tests. |
| caller_body.var_debug_info.append(&mut callee_body.var_debug_info); |
| } |
| caller_body.basic_blocks_mut().append(callee_body.basic_blocks_mut()); |
| |
| caller_body[callsite.block].terminator = Some(Terminator { |
| source_info: callsite.source_info, |
| kind: TerminatorKind::Goto { target: integrator.map_block(START_BLOCK) }, |
| }); |
| |
| // Copy required constants from the callee_body into the caller_body. Although we are only |
| // pushing unevaluated consts to `required_consts`, here they may have been evaluated |
| // because we are calling `instantiate_and_normalize_erasing_regions` -- so we filter again. |
| caller_body.required_consts.as_mut().unwrap().extend( |
| callee_body.required_consts().into_iter().filter(|ct| ct.const_.is_required_const()), |
| ); |
| // Now that we incorporated the callee's `required_consts`, we can remove the callee from |
| // `mentioned_items` -- but we have to take their `mentioned_items` in return. This does |
| // some extra work here to save the monomorphization collector work later. It helps a lot, |
| // since monomorphization can avoid a lot of work when the "mentioned items" are similar to |
| // the actually used items. By doing this we can entirely avoid visiting the callee! |
| // We need to reconstruct the `required_item` for the callee so that we can find and |
| // remove it. |
| let callee_item = MentionedItem::Fn(func.ty(caller_body, self.tcx)); |
| let caller_mentioned_items = caller_body.mentioned_items.as_mut().unwrap(); |
| if let Some(idx) = caller_mentioned_items.iter().position(|item| item.node == callee_item) { |
| // We found the callee, so remove it and add its items instead. |
| caller_mentioned_items.remove(idx); |
| caller_mentioned_items.extend(callee_body.mentioned_items()); |
| } else { |
| // If we can't find the callee, there's no point in adding its items. Probably it |
| // already got removed by being inlined elsewhere in the same function, so we already |
| // took its items. |
| } |
| } |
| |
| fn make_call_args( |
| &self, |
| args: Box<[Spanned<Operand<'tcx>>]>, |
| callsite: &CallSite<'tcx>, |
| caller_body: &mut Body<'tcx>, |
| callee_body: &Body<'tcx>, |
| return_block: Option<BasicBlock>, |
| ) -> Box<[Local]> { |
| 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() { |
| // FIXME(edition_2024): switch back to a normal method call. |
| let mut args = <_>::into_iter(args); |
| let self_ = self.create_temp_if_necessary( |
| args.next().unwrap().node, |
| callsite, |
| caller_body, |
| return_block, |
| ); |
| let tuple = self.create_temp_if_necessary( |
| args.next().unwrap().node, |
| callsite, |
| caller_body, |
| return_block, |
| ); |
| 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, FieldIdx::new(i), ty)); |
| |
| // Spill to a local to make e.g., `tmp0`. |
| self.create_temp_if_necessary(tuple_field, callsite, caller_body, return_block) |
| }); |
| |
| closure_ref_arg.chain(tuple_tmp_args).collect() |
| } else { |
| // FIXME(edition_2024): switch back to a normal method call. |
| <_>::into_iter(args) |
| .map(|a| self.create_temp_if_necessary(a.node, callsite, caller_body, return_block)) |
| .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>, |
| return_block: Option<BasicBlock>, |
| ) -> 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, return_block); |
| 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>, |
| return_block: Option<BasicBlock>, |
| ) -> 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) = return_block { |
| caller_body[block].statements.insert(0, Statement { |
| source_info: callsite.source_info, |
| kind: StatementKind::StorageDead(local), |
| }); |
| } |
| |
| local |
| } |
| } |
| |
| /** |
| * 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<Local>, |
| new_scopes: RangeFrom<SourceScope>, |
| new_blocks: RangeFrom<BasicBlock>, |
| destination: Local, |
| callsite_scope: SourceScopeData<'tcx>, |
| callsite: &'a CallSite<'tcx>, |
| cleanup_block: UnwindAction, |
| in_cleanup_block: bool, |
| return_block: Option<BasicBlock>, |
| tcx: TyCtxt<'tcx>, |
| always_live_locals: BitSet<Local>, |
| } |
| |
| impl Integrator<'_, '_> { |
| fn map_local(&self, local: Local) -> Local { |
| let new = if local == RETURN_PLACE { |
| self.destination |
| } 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 |
| } |
| |
| fn map_unwind(&self, unwind: UnwindAction) -> UnwindAction { |
| if self.in_cleanup_block { |
| match unwind { |
| UnwindAction::Cleanup(_) | UnwindAction::Continue => { |
| bug!("cleanup on cleanup block"); |
| } |
| UnwindAction::Unreachable | UnwindAction::Terminate(_) => return unwind, |
| } |
| } |
| |
| match unwind { |
| UnwindAction::Unreachable | UnwindAction::Terminate(_) => unwind, |
| UnwindAction::Cleanup(target) => UnwindAction::Cleanup(self.map_block(target)), |
| // Add an unwind edge to the original call's cleanup block |
| UnwindAction::Continue => self.cleanup_block, |
| } |
| } |
| } |
| |
| 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_data(&mut self, scope_data: &mut SourceScopeData<'tcx>) { |
| self.super_source_scope_data(scope_data); |
| if scope_data.parent_scope.is_none() { |
| // Attach the outermost callee scope as a child of the callsite |
| // scope, via the `parent_scope` and `inlined_parent_scope` chains. |
| scope_data.parent_scope = Some(self.callsite.source_info.scope); |
| assert_eq!(scope_data.inlined_parent_scope, None); |
| scope_data.inlined_parent_scope = if self.callsite_scope.inlined.is_some() { |
| Some(self.callsite.source_info.scope) |
| } else { |
| self.callsite_scope.inlined_parent_scope |
| }; |
| |
| // Mark the outermost callee scope as an inlined one. |
| assert_eq!(scope_data.inlined, None); |
| scope_data.inlined = Some((self.callsite.callee, self.callsite.source_info.span)); |
| } else if scope_data.inlined_parent_scope.is_none() { |
| // Make it easy to find the scope with `inlined` set above. |
| scope_data.inlined_parent_scope = Some(self.map_scope(OUTERMOST_SOURCE_SCOPE)); |
| } |
| } |
| |
| fn visit_source_scope(&mut self, scope: &mut SourceScope) { |
| *scope = self.map_scope(*scope); |
| } |
| |
| 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::CoroutineDrop | 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, .. } => { |
| *target = self.map_block(*target); |
| *unwind = self.map_unwind(*unwind); |
| } |
| TerminatorKind::TailCall { .. } => { |
| // check_mir_body forbids tail calls |
| unreachable!() |
| } |
| TerminatorKind::Call { ref mut target, ref mut unwind, .. } => { |
| if let Some(ref mut tgt) = *target { |
| *tgt = self.map_block(*tgt); |
| } |
| *unwind = self.map_unwind(*unwind); |
| } |
| TerminatorKind::Assert { ref mut target, ref mut unwind, .. } => { |
| *target = self.map_block(*target); |
| *unwind = self.map_unwind(*unwind); |
| } |
| TerminatorKind::Return => { |
| terminator.kind = if let Some(tgt) = self.return_block { |
| TerminatorKind::Goto { target: tgt } |
| } else { |
| TerminatorKind::Unreachable |
| } |
| } |
| TerminatorKind::UnwindResume => { |
| terminator.kind = match self.cleanup_block { |
| UnwindAction::Cleanup(tgt) => TerminatorKind::Goto { target: tgt }, |
| UnwindAction::Continue => TerminatorKind::UnwindResume, |
| UnwindAction::Unreachable => TerminatorKind::Unreachable, |
| UnwindAction::Terminate(reason) => TerminatorKind::UnwindTerminate(reason), |
| }; |
| } |
| TerminatorKind::UnwindTerminate(_) => {} |
| 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 targets, ref mut unwind, .. } => { |
| for tgt in targets.iter_mut() { |
| *tgt = self.map_block(*tgt); |
| } |
| *unwind = self.map_unwind(*unwind); |
| } |
| } |
| } |
| } |
| |
| #[instrument(skip(tcx), level = "debug")] |
| fn try_instance_mir<'tcx>( |
| tcx: TyCtxt<'tcx>, |
| instance: InstanceKind<'tcx>, |
| ) -> Result<&'tcx Body<'tcx>, &'static str> { |
| if let ty::InstanceKind::DropGlue(_, Some(ty)) |
| | ty::InstanceKind::AsyncDropGlueCtorShim(_, Some(ty)) = instance |
| && let ty::Adt(def, args) = ty.kind() |
| { |
| let fields = def.all_fields(); |
| for field in fields { |
| let field_ty = field.ty(tcx, args); |
| if field_ty.has_param() && field_ty.has_aliases() { |
| return Err("cannot build drop shim for polymorphic type"); |
| } |
| } |
| } |
| Ok(tcx.instance_mir(instance)) |
| } |
| |
| fn body_is_forwarder(body: &Body<'_>) -> bool { |
| let TerminatorKind::Call { target, .. } = body.basic_blocks[START_BLOCK].terminator().kind |
| else { |
| return false; |
| }; |
| if let Some(target) = target { |
| let TerminatorKind::Return = body.basic_blocks[target].terminator().kind else { |
| return false; |
| }; |
| } |
| |
| let max_blocks = if !body.is_polymorphic { |
| 2 |
| } else if target.is_none() { |
| 3 |
| } else { |
| 4 |
| }; |
| if body.basic_blocks.len() > max_blocks { |
| return false; |
| } |
| |
| body.basic_blocks.iter_enumerated().all(|(bb, bb_data)| { |
| bb == START_BLOCK |
| || matches!( |
| bb_data.terminator().kind, |
| TerminatorKind::Return |
| | TerminatorKind::Drop { .. } |
| | TerminatorKind::UnwindResume |
| | TerminatorKind::UnwindTerminate(_) |
| ) |
| }) |
| } |
