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Diffstat (limited to 'compiler/rustc_mir_transform/src/inline.rs')
| -rw-r--r-- | compiler/rustc_mir_transform/src/inline.rs | 1006 |
1 files changed, 1006 insertions, 0 deletions
diff --git a/compiler/rustc_mir_transform/src/inline.rs b/compiler/rustc_mir_transform/src/inline.rs new file mode 100644 index 000000000..76b1522f3 --- /dev/null +++ b/compiler/rustc_mir_transform/src/inline.rs @@ -0,0 +1,1006 @@ +//! Inlining pass for MIR functions +use crate::deref_separator::deref_finder; +use rustc_attr::InlineAttr; +use rustc_const_eval::transform::validate::equal_up_to_regions; +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::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}; + +pub(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<BasicBlock>, + source_info: SourceInfo, +} + +impl<'tcx> MirPass<'tcx> for Inline { + fn is_enabled(&self, sess: &rustc_session::Session) -> bool { + if let Some(enabled) = sess.opts.unstable_opts.inline_mir { + return enabled; + } + + // rust-lang/rust#101004: reverted to old inlining decision logic + sess.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); + 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 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 mut this = Inliner { + tcx, + param_env, + codegen_fn_attrs: tcx.codegen_fn_attrs(def_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, + /// Stack of inlined Instances. + history: Vec<ty::Instance<'tcx>>, + /// 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<BasicBlock>) { + 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<std::ops::Range<BasicBlock>, &'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 Ok(callee_body) = callsite.callee.try_subst_mir_and_normalize_erasing_regions( + self.tcx, + self.param_env, + callee_body.clone(), + ) else { + return Err("failed to normalize callee body"); + }; + + // Check call signature compatibility. + // Normally, this shouldn't be required, but trait normalization failure can create a + // validation ICE. + 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; + let output_type = callee_body.return_ty(); + if !equal_up_to_regions(self.tcx, self.param_env, output_type, destination_ty) { + trace!(?output_type, ?destination_ty); + return Err("failed to normalize return type"); + } + if callsite.fn_sig.abi() == Abi::RustCall { + let (arg_tuple, skipped_args) = match &args[..] { + [arg_tuple] => (arg_tuple, 0), + [_, arg_tuple] => (arg_tuple, 1), + _ => bug!("Expected `rust-call` to have 1 or 2 args"), + }; + + let arg_tuple_ty = arg_tuple.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 + arg_tuple_tys.iter().zip(callee_body.args_iter().skip(skipped_args)) + { + let input_type = callee_body.local_decls[input].ty; + if !equal_up_to_regions(self.tcx, self.param_env, arg_ty, input_type) { + 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.ty(&caller_body.local_decls, self.tcx); + if !equal_up_to_regions(self.tcx, self.param_env, arg_ty, input_type) { + 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 { + 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 callee_def_id.is_local() { + // Avoid a cycle here by only using `instance_mir` only if we have + // a lower `DefPathHash` than the callee. This ensures that the callee will + // not inline us. This trick even works with incremental compilation, + // since `DefPathHash` is stable. + if self.tcx.def_path_hash(caller_def_id).local_hash() + < self.tcx.def_path_hash(callee_def_id).local_hash() + { + 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_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(); + if let TerminatorKind::Call { ref func, target, .. } = 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.try_normalize_erasing_regions(self.param_env, substs).ok()?; + let callee = + Instance::resolve(self.tcx, self.param_env, def_id, substs).ok().flatten()?; + + if let InstanceDef::Virtual(..) | InstanceDef::Intrinsic(_) = callee.def { + return None; + } + + if self.history.contains(&callee) { + return None; + } + + let fn_sig = self.tcx.bound_fn_sig(def_id).subst(self.tcx, substs); + + return Some(CallSite { + callee, + fn_sig, + block: bb, + 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> { + match callee_attrs.inline { + InlineAttr::Never => return Err("never inline hint"), + InlineAttr::Always | InlineAttr::Hint => {} + InlineAttr::None => { + if self.tcx.sess.mir_opt_level() <= 2 { + return Err("at mir-opt-level=2, only #[inline] is inlined"); + } + } + } + + // 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.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 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::Deinit(_) + | 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 { target: 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, _) = + *callsite.callee.subst_mir(self.tcx, &f.literal.ty()).kind() + { + // Don't give intrinsics the extra penalty for calls + if tcx.is_intrinsic(def_id) { + 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 dest_needs_borrow(destination) { + trace!("creating temp for return destination"); + let dest = Rvalue::Ref( + self.tcx.lifetimes.re_erased, + BorrowKind::Mut { allow_two_phase_borrow: false }, + destination, + ); + 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 + }; + + // 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 = + self.tcx.with_stable_hashing_context(|hcx| LocalExpnId::fresh(expn_data, hcx)); + 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, + callsite_scope: caller_body.source_scopes[callsite.source_info.scope].clone(), + callsite, + 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); + + // 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.kind(), ConstKind::Unevaluated(_)), + None => true, + } + }), + ); + } + kind => bug!("unexpected terminator kind {:?}", kind), + } + } + + fn make_call_args( + &self, + args: Vec<Operand<'tcx>>, + callsite: &CallSite<'tcx>, + caller_body: &mut Body<'tcx>, + callee_body: &Body<'tcx>, + ) -> Vec<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() { + 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<u64> { + 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<Local>, + new_scopes: RangeFrom<SourceScope>, + new_blocks: RangeFrom<BasicBlock>, + destination: Place<'tcx>, + callsite_scope: SourceScopeData<'tcx>, + callsite: &'a CallSite<'tcx>, + cleanup_block: Option<BasicBlock>, + in_cleanup_block: bool, + tcx: TyCtxt<'tcx>, + expn_data: LocalExpnId, + always_live_locals: BitSet<Local>, +} + +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_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_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 target, ref mut cleanup, .. } => { + if let Some(ref mut tgt) = *target { + *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.callsite.target { + 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; + } + } + } + } +} |