| use rustc_hir as hir; |
| use rustc_hir::def_id::DefId; |
| use rustc_hir::lang_items::LangItem; |
| use rustc_middle::mir::*; |
| use rustc_middle::query::Providers; |
| use rustc_middle::ty::InternalSubsts; |
| use rustc_middle::ty::{self, EarlyBinder, GeneratorSubsts, Ty, TyCtxt}; |
| use rustc_target::abi::{FieldIdx, VariantIdx, FIRST_VARIANT}; |
| |
| use rustc_index::{Idx, IndexVec}; |
| |
| use rustc_span::Span; |
| use rustc_target::spec::abi::Abi; |
| |
| use std::fmt; |
| use std::iter; |
| |
| use crate::{ |
| abort_unwinding_calls, add_call_guards, add_moves_for_packed_drops, deref_separator, |
| pass_manager as pm, remove_noop_landing_pads, simplify, |
| }; |
| use rustc_middle::mir::patch::MirPatch; |
| use rustc_mir_dataflow::elaborate_drops::{self, DropElaborator, DropFlagMode, DropStyle}; |
| |
| pub fn provide(providers: &mut Providers) { |
| providers.mir_shims = make_shim; |
| } |
| |
| fn make_shim<'tcx>(tcx: TyCtxt<'tcx>, instance: ty::InstanceDef<'tcx>) -> Body<'tcx> { |
| debug!("make_shim({:?})", instance); |
| |
| let mut result = match instance { |
| ty::InstanceDef::Item(..) => bug!("item {:?} passed to make_shim", instance), |
| ty::InstanceDef::VTableShim(def_id) => { |
| build_call_shim(tcx, instance, Some(Adjustment::Deref), CallKind::Direct(def_id)) |
| } |
| ty::InstanceDef::FnPtrShim(def_id, ty) => { |
| let trait_ = tcx.trait_of_item(def_id).unwrap(); |
| let adjustment = match tcx.fn_trait_kind_from_def_id(trait_) { |
| Some(ty::ClosureKind::FnOnce) => Adjustment::Identity, |
| Some(ty::ClosureKind::FnMut | ty::ClosureKind::Fn) => Adjustment::Deref, |
| None => bug!("fn pointer {:?} is not an fn", ty), |
| }; |
| |
| build_call_shim(tcx, instance, Some(adjustment), CallKind::Indirect(ty)) |
| } |
| // We are generating a call back to our def-id, which the |
| // codegen backend knows to turn to an actual call, be it |
| // a virtual call, or a direct call to a function for which |
| // indirect calls must be codegen'd differently than direct ones |
| // (such as `#[track_caller]`). |
| ty::InstanceDef::ReifyShim(def_id) => { |
| build_call_shim(tcx, instance, None, CallKind::Direct(def_id)) |
| } |
| ty::InstanceDef::ClosureOnceShim { call_once: _, track_caller: _ } => { |
| let fn_mut = tcx.require_lang_item(LangItem::FnMut, None); |
| let call_mut = tcx |
| .associated_items(fn_mut) |
| .in_definition_order() |
| .find(|it| it.kind == ty::AssocKind::Fn) |
| .unwrap() |
| .def_id; |
| |
| build_call_shim(tcx, instance, Some(Adjustment::RefMut), CallKind::Direct(call_mut)) |
| } |
| |
| ty::InstanceDef::DropGlue(def_id, ty) => { |
| // FIXME(#91576): Drop shims for generators aren't subject to the MIR passes at the end |
| // of this function. Is this intentional? |
| if let Some(ty::Generator(gen_def_id, substs, _)) = ty.map(Ty::kind) { |
| let body = tcx.optimized_mir(*gen_def_id).generator_drop().unwrap(); |
| let body = EarlyBinder::new(body.clone()).subst(tcx, substs); |
| debug!("make_shim({:?}) = {:?}", instance, body); |
| return body; |
| } |
| |
| build_drop_shim(tcx, def_id, ty) |
| } |
| ty::InstanceDef::ThreadLocalShim(..) => build_thread_local_shim(tcx, instance), |
| ty::InstanceDef::CloneShim(def_id, ty) => build_clone_shim(tcx, def_id, ty), |
| ty::InstanceDef::FnPtrAddrShim(def_id, ty) => build_fn_ptr_addr_shim(tcx, def_id, ty), |
| ty::InstanceDef::Virtual(..) => { |
| bug!("InstanceDef::Virtual ({:?}) is for direct calls only", instance) |
| } |
| ty::InstanceDef::Intrinsic(_) => { |
| bug!("creating shims from intrinsics ({:?}) is unsupported", instance) |
| } |
| }; |
| debug!("make_shim({:?}) = untransformed {:?}", instance, result); |
| |
| pm::run_passes( |
| tcx, |
| &mut result, |
| &[ |
| &add_moves_for_packed_drops::AddMovesForPackedDrops, |
| &deref_separator::Derefer, |
| &remove_noop_landing_pads::RemoveNoopLandingPads, |
| &simplify::SimplifyCfg::MakeShim, |
| &add_call_guards::CriticalCallEdges, |
| &abort_unwinding_calls::AbortUnwindingCalls, |
| ], |
| Some(MirPhase::Runtime(RuntimePhase::Optimized)), |
| ); |
| |
| debug!("make_shim({:?}) = {:?}", instance, result); |
| |
| result |
| } |
| |
| #[derive(Copy, Clone, Debug, PartialEq)] |
| enum Adjustment { |
| /// Pass the receiver as-is. |
| Identity, |
| |
| /// We get passed `&[mut] self` and call the target with `*self`. |
| /// |
| /// This either copies `self` (if `Self: Copy`, eg. for function items), or moves out of it |
| /// (for `VTableShim`, which effectively is passed `&own Self`). |
| Deref, |
| |
| /// We get passed `self: Self` and call the target with `&mut self`. |
| /// |
| /// In this case we need to ensure that the `Self` is dropped after the call, as the callee |
| /// won't do it for us. |
| RefMut, |
| } |
| |
| #[derive(Copy, Clone, Debug, PartialEq)] |
| enum CallKind<'tcx> { |
| /// Call the `FnPtr` that was passed as the receiver. |
| Indirect(Ty<'tcx>), |
| |
| /// Call a known `FnDef`. |
| Direct(DefId), |
| } |
| |
| fn local_decls_for_sig<'tcx>( |
| sig: &ty::FnSig<'tcx>, |
| span: Span, |
| ) -> IndexVec<Local, LocalDecl<'tcx>> { |
| iter::once(LocalDecl::new(sig.output(), span)) |
| .chain(sig.inputs().iter().map(|ity| LocalDecl::new(*ity, span).immutable())) |
| .collect() |
| } |
| |
| fn build_drop_shim<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId, ty: Option<Ty<'tcx>>) -> Body<'tcx> { |
| debug!("build_drop_shim(def_id={:?}, ty={:?})", def_id, ty); |
| |
| assert!(!matches!(ty, Some(ty) if ty.is_generator())); |
| |
| let substs = if let Some(ty) = ty { |
| tcx.mk_substs(&[ty.into()]) |
| } else { |
| InternalSubsts::identity_for_item(tcx, def_id) |
| }; |
| let sig = tcx.fn_sig(def_id).subst(tcx, substs); |
| let sig = tcx.erase_late_bound_regions(sig); |
| let span = tcx.def_span(def_id); |
| |
| let source_info = SourceInfo::outermost(span); |
| |
| let return_block = BasicBlock::new(1); |
| let mut blocks = IndexVec::with_capacity(2); |
| let block = |blocks: &mut IndexVec<_, _>, kind| { |
| blocks.push(BasicBlockData { |
| statements: vec![], |
| terminator: Some(Terminator { source_info, kind }), |
| is_cleanup: false, |
| }) |
| }; |
| block(&mut blocks, TerminatorKind::Goto { target: return_block }); |
| block(&mut blocks, TerminatorKind::Return); |
| |
| let source = MirSource::from_instance(ty::InstanceDef::DropGlue(def_id, ty)); |
| let mut body = |
| new_body(source, blocks, local_decls_for_sig(&sig, span), sig.inputs().len(), span); |
| |
| // The first argument (index 0), but add 1 for the return value. |
| let mut dropee_ptr = Place::from(Local::new(1 + 0)); |
| if tcx.sess.opts.unstable_opts.mir_emit_retag { |
| // We want to treat the function argument as if it was passed by `&mut`. As such, we |
| // generate |
| // ``` |
| // temp = &mut *arg; |
| // Retag(temp, FnEntry) |
| // ``` |
| // It's important that we do this first, before anything that depends on `dropee_ptr` |
| // has been put into the body. |
| let reborrow = Rvalue::Ref( |
| tcx.lifetimes.re_erased, |
| BorrowKind::Mut { allow_two_phase_borrow: false }, |
| tcx.mk_place_deref(dropee_ptr), |
| ); |
| let ref_ty = reborrow.ty(body.local_decls(), tcx); |
| dropee_ptr = body.local_decls.push(LocalDecl::new(ref_ty, span)).into(); |
| let new_statements = [ |
| StatementKind::Assign(Box::new((dropee_ptr, reborrow))), |
| StatementKind::Retag(RetagKind::FnEntry, Box::new(dropee_ptr)), |
| ]; |
| for s in new_statements { |
| body.basic_blocks_mut()[START_BLOCK] |
| .statements |
| .push(Statement { source_info, kind: s }); |
| } |
| } |
| |
| if ty.is_some() { |
| let patch = { |
| let param_env = tcx.param_env_reveal_all_normalized(def_id); |
| let mut elaborator = |
| DropShimElaborator { body: &body, patch: MirPatch::new(&body), tcx, param_env }; |
| let dropee = tcx.mk_place_deref(dropee_ptr); |
| let resume_block = elaborator.patch.resume_block(); |
| elaborate_drops::elaborate_drop( |
| &mut elaborator, |
| source_info, |
| dropee, |
| (), |
| return_block, |
| elaborate_drops::Unwind::To(resume_block), |
| START_BLOCK, |
| ); |
| elaborator.patch |
| }; |
| patch.apply(&mut body); |
| } |
| |
| body |
| } |
| |
| fn new_body<'tcx>( |
| source: MirSource<'tcx>, |
| basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>, |
| local_decls: IndexVec<Local, LocalDecl<'tcx>>, |
| arg_count: usize, |
| span: Span, |
| ) -> Body<'tcx> { |
| Body::new( |
| source, |
| basic_blocks, |
| IndexVec::from_elem_n( |
| SourceScopeData { |
| span, |
| parent_scope: None, |
| inlined: None, |
| inlined_parent_scope: None, |
| local_data: ClearCrossCrate::Clear, |
| }, |
| 1, |
| ), |
| local_decls, |
| IndexVec::new(), |
| arg_count, |
| vec![], |
| span, |
| None, |
| // FIXME(compiler-errors): is this correct? |
| None, |
| ) |
| } |
| |
| pub struct DropShimElaborator<'a, 'tcx> { |
| pub body: &'a Body<'tcx>, |
| pub patch: MirPatch<'tcx>, |
| pub tcx: TyCtxt<'tcx>, |
| pub param_env: ty::ParamEnv<'tcx>, |
| } |
| |
| impl fmt::Debug for DropShimElaborator<'_, '_> { |
| fn fmt(&self, _f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> { |
| Ok(()) |
| } |
| } |
| |
| impl<'a, 'tcx> DropElaborator<'a, 'tcx> for DropShimElaborator<'a, 'tcx> { |
| type Path = (); |
| |
| fn patch(&mut self) -> &mut MirPatch<'tcx> { |
| &mut self.patch |
| } |
| fn body(&self) -> &'a Body<'tcx> { |
| self.body |
| } |
| fn tcx(&self) -> TyCtxt<'tcx> { |
| self.tcx |
| } |
| fn param_env(&self) -> ty::ParamEnv<'tcx> { |
| self.param_env |
| } |
| |
| fn drop_style(&self, _path: Self::Path, mode: DropFlagMode) -> DropStyle { |
| match mode { |
| DropFlagMode::Shallow => { |
| // Drops for the contained fields are "shallow" and "static" - they will simply call |
| // the field's own drop glue. |
| DropStyle::Static |
| } |
| DropFlagMode::Deep => { |
| // The top-level drop is "deep" and "open" - it will be elaborated to a drop ladder |
| // dropping each field contained in the value. |
| DropStyle::Open |
| } |
| } |
| } |
| |
| fn get_drop_flag(&mut self, _path: Self::Path) -> Option<Operand<'tcx>> { |
| None |
| } |
| |
| fn clear_drop_flag(&mut self, _location: Location, _path: Self::Path, _mode: DropFlagMode) {} |
| |
| fn field_subpath(&self, _path: Self::Path, _field: FieldIdx) -> Option<Self::Path> { |
| None |
| } |
| fn deref_subpath(&self, _path: Self::Path) -> Option<Self::Path> { |
| None |
| } |
| fn downcast_subpath(&self, _path: Self::Path, _variant: VariantIdx) -> Option<Self::Path> { |
| Some(()) |
| } |
| fn array_subpath(&self, _path: Self::Path, _index: u64, _size: u64) -> Option<Self::Path> { |
| None |
| } |
| } |
| |
| fn build_thread_local_shim<'tcx>(tcx: TyCtxt<'tcx>, instance: ty::InstanceDef<'tcx>) -> Body<'tcx> { |
| let def_id = instance.def_id(); |
| |
| let span = tcx.def_span(def_id); |
| let source_info = SourceInfo::outermost(span); |
| |
| let mut blocks = IndexVec::with_capacity(1); |
| blocks.push(BasicBlockData { |
| statements: vec![Statement { |
| source_info, |
| kind: StatementKind::Assign(Box::new(( |
| Place::return_place(), |
| Rvalue::ThreadLocalRef(def_id), |
| ))), |
| }], |
| terminator: Some(Terminator { source_info, kind: TerminatorKind::Return }), |
| is_cleanup: false, |
| }); |
| |
| new_body( |
| MirSource::from_instance(instance), |
| blocks, |
| IndexVec::from_raw(vec![LocalDecl::new(tcx.thread_local_ptr_ty(def_id), span)]), |
| 0, |
| span, |
| ) |
| } |
| |
| /// Builds a `Clone::clone` shim for `self_ty`. Here, `def_id` is `Clone::clone`. |
| fn build_clone_shim<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId, self_ty: Ty<'tcx>) -> Body<'tcx> { |
| debug!("build_clone_shim(def_id={:?})", def_id); |
| |
| let param_env = tcx.param_env_reveal_all_normalized(def_id); |
| |
| let mut builder = CloneShimBuilder::new(tcx, def_id, self_ty); |
| let is_copy = self_ty.is_copy_modulo_regions(tcx, param_env); |
| |
| let dest = Place::return_place(); |
| let src = tcx.mk_place_deref(Place::from(Local::new(1 + 0))); |
| |
| match self_ty.kind() { |
| _ if is_copy => builder.copy_shim(), |
| ty::Closure(_, substs) => { |
| builder.tuple_like_shim(dest, src, substs.as_closure().upvar_tys()) |
| } |
| ty::Tuple(..) => builder.tuple_like_shim(dest, src, self_ty.tuple_fields()), |
| ty::Generator(gen_def_id, substs, hir::Movability::Movable) => { |
| builder.generator_shim(dest, src, *gen_def_id, substs.as_generator()) |
| } |
| _ => bug!("clone shim for `{:?}` which is not `Copy` and is not an aggregate", self_ty), |
| }; |
| |
| builder.into_mir() |
| } |
| |
| struct CloneShimBuilder<'tcx> { |
| tcx: TyCtxt<'tcx>, |
| def_id: DefId, |
| local_decls: IndexVec<Local, LocalDecl<'tcx>>, |
| blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>, |
| span: Span, |
| sig: ty::FnSig<'tcx>, |
| } |
| |
| impl<'tcx> CloneShimBuilder<'tcx> { |
| fn new(tcx: TyCtxt<'tcx>, def_id: DefId, self_ty: Ty<'tcx>) -> Self { |
| // we must subst the self_ty because it's |
| // otherwise going to be TySelf and we can't index |
| // or access fields of a Place of type TySelf. |
| let sig = tcx.fn_sig(def_id).subst(tcx, &[self_ty.into()]); |
| let sig = tcx.erase_late_bound_regions(sig); |
| let span = tcx.def_span(def_id); |
| |
| CloneShimBuilder { |
| tcx, |
| def_id, |
| local_decls: local_decls_for_sig(&sig, span), |
| blocks: IndexVec::new(), |
| span, |
| sig, |
| } |
| } |
| |
| fn into_mir(self) -> Body<'tcx> { |
| let source = MirSource::from_instance(ty::InstanceDef::CloneShim( |
| self.def_id, |
| self.sig.inputs_and_output[0], |
| )); |
| new_body(source, self.blocks, self.local_decls, self.sig.inputs().len(), self.span) |
| } |
| |
| fn source_info(&self) -> SourceInfo { |
| SourceInfo::outermost(self.span) |
| } |
| |
| fn block( |
| &mut self, |
| statements: Vec<Statement<'tcx>>, |
| kind: TerminatorKind<'tcx>, |
| is_cleanup: bool, |
| ) -> BasicBlock { |
| let source_info = self.source_info(); |
| self.blocks.push(BasicBlockData { |
| statements, |
| terminator: Some(Terminator { source_info, kind }), |
| is_cleanup, |
| }) |
| } |
| |
| /// Gives the index of an upcoming BasicBlock, with an offset. |
| /// offset=0 will give you the index of the next BasicBlock, |
| /// offset=1 will give the index of the next-to-next block, |
| /// offset=-1 will give you the index of the last-created block |
| fn block_index_offset(&self, offset: usize) -> BasicBlock { |
| BasicBlock::new(self.blocks.len() + offset) |
| } |
| |
| fn make_statement(&self, kind: StatementKind<'tcx>) -> Statement<'tcx> { |
| Statement { source_info: self.source_info(), kind } |
| } |
| |
| fn copy_shim(&mut self) { |
| let rcvr = self.tcx.mk_place_deref(Place::from(Local::new(1 + 0))); |
| let ret_statement = self.make_statement(StatementKind::Assign(Box::new(( |
| Place::return_place(), |
| Rvalue::Use(Operand::Copy(rcvr)), |
| )))); |
| self.block(vec![ret_statement], TerminatorKind::Return, false); |
| } |
| |
| fn make_place(&mut self, mutability: Mutability, ty: Ty<'tcx>) -> Place<'tcx> { |
| let span = self.span; |
| let mut local = LocalDecl::new(ty, span); |
| if mutability.is_not() { |
| local = local.immutable(); |
| } |
| Place::from(self.local_decls.push(local)) |
| } |
| |
| fn make_clone_call( |
| &mut self, |
| dest: Place<'tcx>, |
| src: Place<'tcx>, |
| ty: Ty<'tcx>, |
| next: BasicBlock, |
| cleanup: BasicBlock, |
| ) { |
| let tcx = self.tcx; |
| |
| // `func == Clone::clone(&ty) -> ty` |
| let func_ty = tcx.mk_fn_def(self.def_id, [ty]); |
| let func = Operand::Constant(Box::new(Constant { |
| span: self.span, |
| user_ty: None, |
| literal: ConstantKind::zero_sized(func_ty), |
| })); |
| |
| let ref_loc = self.make_place( |
| Mutability::Not, |
| tcx.mk_ref(tcx.lifetimes.re_erased, ty::TypeAndMut { ty, mutbl: hir::Mutability::Not }), |
| ); |
| |
| // `let ref_loc: &ty = &src;` |
| let statement = self.make_statement(StatementKind::Assign(Box::new(( |
| ref_loc, |
| Rvalue::Ref(tcx.lifetimes.re_erased, BorrowKind::Shared, src), |
| )))); |
| |
| // `let loc = Clone::clone(ref_loc);` |
| self.block( |
| vec![statement], |
| TerminatorKind::Call { |
| func, |
| args: vec![Operand::Move(ref_loc)], |
| destination: dest, |
| target: Some(next), |
| unwind: UnwindAction::Cleanup(cleanup), |
| from_hir_call: true, |
| fn_span: self.span, |
| }, |
| false, |
| ); |
| } |
| |
| fn clone_fields<I>( |
| &mut self, |
| dest: Place<'tcx>, |
| src: Place<'tcx>, |
| target: BasicBlock, |
| mut unwind: BasicBlock, |
| tys: I, |
| ) -> BasicBlock |
| where |
| I: IntoIterator<Item = Ty<'tcx>>, |
| { |
| // For an iterator of length n, create 2*n + 1 blocks. |
| for (i, ity) in tys.into_iter().enumerate() { |
| // Each iteration creates two blocks, referred to here as block 2*i and block 2*i + 1. |
| // |
| // Block 2*i attempts to clone the field. If successful it branches to 2*i + 2 (the |
| // next clone block). If unsuccessful it branches to the previous unwind block, which |
| // is initially the `unwind` argument passed to this function. |
| // |
| // Block 2*i + 1 is the unwind block for this iteration. It drops the cloned value |
| // created by block 2*i. We store this block in `unwind` so that the next clone block |
| // will unwind to it if cloning fails. |
| |
| let field = FieldIdx::new(i); |
| let src_field = self.tcx.mk_place_field(src, field, ity); |
| |
| let dest_field = self.tcx.mk_place_field(dest, field, ity); |
| |
| let next_unwind = self.block_index_offset(1); |
| let next_block = self.block_index_offset(2); |
| self.make_clone_call(dest_field, src_field, ity, next_block, unwind); |
| self.block( |
| vec![], |
| TerminatorKind::Drop { |
| place: dest_field, |
| target: unwind, |
| unwind: UnwindAction::Terminate, |
| replace: false, |
| }, |
| true, |
| ); |
| unwind = next_unwind; |
| } |
| // If all clones succeed then we end up here. |
| self.block(vec![], TerminatorKind::Goto { target }, false); |
| unwind |
| } |
| |
| fn tuple_like_shim<I>(&mut self, dest: Place<'tcx>, src: Place<'tcx>, tys: I) |
| where |
| I: IntoIterator<Item = Ty<'tcx>>, |
| { |
| self.block(vec![], TerminatorKind::Goto { target: self.block_index_offset(3) }, false); |
| let unwind = self.block(vec![], TerminatorKind::Resume, true); |
| let target = self.block(vec![], TerminatorKind::Return, false); |
| |
| let _final_cleanup_block = self.clone_fields(dest, src, target, unwind, tys); |
| } |
| |
| fn generator_shim( |
| &mut self, |
| dest: Place<'tcx>, |
| src: Place<'tcx>, |
| gen_def_id: DefId, |
| substs: GeneratorSubsts<'tcx>, |
| ) { |
| self.block(vec![], TerminatorKind::Goto { target: self.block_index_offset(3) }, false); |
| let unwind = self.block(vec![], TerminatorKind::Resume, true); |
| // This will get overwritten with a switch once we know the target blocks |
| let switch = self.block(vec![], TerminatorKind::Unreachable, false); |
| let unwind = self.clone_fields(dest, src, switch, unwind, substs.upvar_tys()); |
| let target = self.block(vec![], TerminatorKind::Return, false); |
| let unreachable = self.block(vec![], TerminatorKind::Unreachable, false); |
| let mut cases = Vec::with_capacity(substs.state_tys(gen_def_id, self.tcx).count()); |
| for (index, state_tys) in substs.state_tys(gen_def_id, self.tcx).enumerate() { |
| let variant_index = VariantIdx::new(index); |
| let dest = self.tcx.mk_place_downcast_unnamed(dest, variant_index); |
| let src = self.tcx.mk_place_downcast_unnamed(src, variant_index); |
| let clone_block = self.block_index_offset(1); |
| let start_block = self.block( |
| vec![self.make_statement(StatementKind::SetDiscriminant { |
| place: Box::new(Place::return_place()), |
| variant_index, |
| })], |
| TerminatorKind::Goto { target: clone_block }, |
| false, |
| ); |
| cases.push((index as u128, start_block)); |
| let _final_cleanup_block = self.clone_fields(dest, src, target, unwind, state_tys); |
| } |
| let discr_ty = substs.discr_ty(self.tcx); |
| let temp = self.make_place(Mutability::Mut, discr_ty); |
| let rvalue = Rvalue::Discriminant(src); |
| let statement = self.make_statement(StatementKind::Assign(Box::new((temp, rvalue)))); |
| match &mut self.blocks[switch] { |
| BasicBlockData { statements, terminator: Some(Terminator { kind, .. }), .. } => { |
| statements.push(statement); |
| *kind = TerminatorKind::SwitchInt { |
| discr: Operand::Move(temp), |
| targets: SwitchTargets::new(cases.into_iter(), unreachable), |
| }; |
| } |
| BasicBlockData { terminator: None, .. } => unreachable!(), |
| } |
| } |
| } |
| |
| /// Builds a "call" shim for `instance`. The shim calls the function specified by `call_kind`, |
| /// first adjusting its first argument according to `rcvr_adjustment`. |
| #[instrument(level = "debug", skip(tcx), ret)] |
| fn build_call_shim<'tcx>( |
| tcx: TyCtxt<'tcx>, |
| instance: ty::InstanceDef<'tcx>, |
| rcvr_adjustment: Option<Adjustment>, |
| call_kind: CallKind<'tcx>, |
| ) -> Body<'tcx> { |
| // `FnPtrShim` contains the fn pointer type that a call shim is being built for - this is used |
| // to substitute into the signature of the shim. It is not necessary for users of this |
| // MIR body to perform further substitutions (see `InstanceDef::has_polymorphic_mir_body`). |
| let (sig_substs, untuple_args) = if let ty::InstanceDef::FnPtrShim(_, ty) = instance { |
| let sig = tcx.erase_late_bound_regions(ty.fn_sig(tcx)); |
| |
| let untuple_args = sig.inputs(); |
| |
| // Create substitutions for the `Self` and `Args` generic parameters of the shim body. |
| let arg_tup = tcx.mk_tup(untuple_args); |
| |
| (Some([ty.into(), arg_tup.into()]), Some(untuple_args)) |
| } else { |
| (None, None) |
| }; |
| |
| let def_id = instance.def_id(); |
| let sig = tcx.fn_sig(def_id); |
| let sig = sig.map_bound(|sig| tcx.erase_late_bound_regions(sig)); |
| |
| assert_eq!(sig_substs.is_some(), !instance.has_polymorphic_mir_body()); |
| let mut sig = |
| if let Some(sig_substs) = sig_substs { sig.subst(tcx, &sig_substs) } else { sig.0 }; |
| |
| if let CallKind::Indirect(fnty) = call_kind { |
| // `sig` determines our local decls, and thus the callee type in the `Call` terminator. This |
| // can only be an `FnDef` or `FnPtr`, but currently will be `Self` since the types come from |
| // the implemented `FnX` trait. |
| |
| // Apply the opposite adjustment to the MIR input. |
| let mut inputs_and_output = sig.inputs_and_output.to_vec(); |
| |
| // Initial signature is `fn(&? Self, Args) -> Self::Output` where `Args` is a tuple of the |
| // fn arguments. `Self` may be passed via (im)mutable reference or by-value. |
| assert_eq!(inputs_and_output.len(), 3); |
| |
| // `Self` is always the original fn type `ty`. The MIR call terminator is only defined for |
| // `FnDef` and `FnPtr` callees, not the `Self` type param. |
| let self_arg = &mut inputs_and_output[0]; |
| *self_arg = match rcvr_adjustment.unwrap() { |
| Adjustment::Identity => fnty, |
| Adjustment::Deref => tcx.mk_imm_ptr(fnty), |
| Adjustment::RefMut => tcx.mk_mut_ptr(fnty), |
| }; |
| sig.inputs_and_output = tcx.mk_type_list(&inputs_and_output); |
| } |
| |
| // FIXME(eddyb) avoid having this snippet both here and in |
| // `Instance::fn_sig` (introduce `InstanceDef::fn_sig`?). |
| if let ty::InstanceDef::VTableShim(..) = instance { |
| // Modify fn(self, ...) to fn(self: *mut Self, ...) |
| let mut inputs_and_output = sig.inputs_and_output.to_vec(); |
| let self_arg = &mut inputs_and_output[0]; |
| debug_assert!(tcx.generics_of(def_id).has_self && *self_arg == tcx.types.self_param); |
| *self_arg = tcx.mk_mut_ptr(*self_arg); |
| sig.inputs_and_output = tcx.mk_type_list(&inputs_and_output); |
| } |
| |
| let span = tcx.def_span(def_id); |
| |
| debug!(?sig); |
| |
| let mut local_decls = local_decls_for_sig(&sig, span); |
| let source_info = SourceInfo::outermost(span); |
| |
| let rcvr_place = || { |
| assert!(rcvr_adjustment.is_some()); |
| Place::from(Local::new(1 + 0)) |
| }; |
| let mut statements = vec![]; |
| |
| let rcvr = rcvr_adjustment.map(|rcvr_adjustment| match rcvr_adjustment { |
| Adjustment::Identity => Operand::Move(rcvr_place()), |
| Adjustment::Deref => Operand::Move(tcx.mk_place_deref(rcvr_place())), |
| Adjustment::RefMut => { |
| // let rcvr = &mut rcvr; |
| let ref_rcvr = local_decls.push( |
| LocalDecl::new( |
| tcx.mk_ref( |
| tcx.lifetimes.re_erased, |
| ty::TypeAndMut { ty: sig.inputs()[0], mutbl: hir::Mutability::Mut }, |
| ), |
| span, |
| ) |
| .immutable(), |
| ); |
| let borrow_kind = BorrowKind::Mut { allow_two_phase_borrow: false }; |
| statements.push(Statement { |
| source_info, |
| kind: StatementKind::Assign(Box::new(( |
| Place::from(ref_rcvr), |
| Rvalue::Ref(tcx.lifetimes.re_erased, borrow_kind, rcvr_place()), |
| ))), |
| }); |
| Operand::Move(Place::from(ref_rcvr)) |
| } |
| }); |
| |
| let (callee, mut args) = match call_kind { |
| // `FnPtr` call has no receiver. Args are untupled below. |
| CallKind::Indirect(_) => (rcvr.unwrap(), vec![]), |
| |
| // `FnDef` call with optional receiver. |
| CallKind::Direct(def_id) => { |
| let ty = tcx.type_of(def_id).subst_identity(); |
| ( |
| Operand::Constant(Box::new(Constant { |
| span, |
| user_ty: None, |
| literal: ConstantKind::zero_sized(ty), |
| })), |
| rcvr.into_iter().collect::<Vec<_>>(), |
| ) |
| } |
| }; |
| |
| let mut arg_range = 0..sig.inputs().len(); |
| |
| // Take the `self` ("receiver") argument out of the range (it's adjusted above). |
| if rcvr_adjustment.is_some() { |
| arg_range.start += 1; |
| } |
| |
| // Take the last argument, if we need to untuple it (handled below). |
| if untuple_args.is_some() { |
| arg_range.end -= 1; |
| } |
| |
| // Pass all of the non-special arguments directly. |
| args.extend(arg_range.map(|i| Operand::Move(Place::from(Local::new(1 + i))))); |
| |
| // Untuple the last argument, if we have to. |
| if let Some(untuple_args) = untuple_args { |
| let tuple_arg = Local::new(1 + (sig.inputs().len() - 1)); |
| args.extend(untuple_args.iter().enumerate().map(|(i, ity)| { |
| Operand::Move(tcx.mk_place_field(Place::from(tuple_arg), FieldIdx::new(i), *ity)) |
| })); |
| } |
| |
| let n_blocks = if let Some(Adjustment::RefMut) = rcvr_adjustment { 5 } else { 2 }; |
| let mut blocks = IndexVec::with_capacity(n_blocks); |
| let block = |blocks: &mut IndexVec<_, _>, statements, kind, is_cleanup| { |
| blocks.push(BasicBlockData { |
| statements, |
| terminator: Some(Terminator { source_info, kind }), |
| is_cleanup, |
| }) |
| }; |
| |
| // BB #0 |
| block( |
| &mut blocks, |
| statements, |
| TerminatorKind::Call { |
| func: callee, |
| args, |
| destination: Place::return_place(), |
| target: Some(BasicBlock::new(1)), |
| unwind: if let Some(Adjustment::RefMut) = rcvr_adjustment { |
| UnwindAction::Cleanup(BasicBlock::new(3)) |
| } else { |
| UnwindAction::Continue |
| }, |
| from_hir_call: true, |
| fn_span: span, |
| }, |
| false, |
| ); |
| |
| if let Some(Adjustment::RefMut) = rcvr_adjustment { |
| // BB #1 - drop for Self |
| block( |
| &mut blocks, |
| vec![], |
| TerminatorKind::Drop { |
| place: rcvr_place(), |
| target: BasicBlock::new(2), |
| unwind: UnwindAction::Continue, |
| replace: false, |
| }, |
| false, |
| ); |
| } |
| // BB #1/#2 - return |
| block(&mut blocks, vec![], TerminatorKind::Return, false); |
| if let Some(Adjustment::RefMut) = rcvr_adjustment { |
| // BB #3 - drop if closure panics |
| block( |
| &mut blocks, |
| vec![], |
| TerminatorKind::Drop { |
| place: rcvr_place(), |
| target: BasicBlock::new(4), |
| unwind: UnwindAction::Terminate, |
| replace: false, |
| }, |
| true, |
| ); |
| |
| // BB #4 - resume |
| block(&mut blocks, vec![], TerminatorKind::Resume, true); |
| } |
| |
| let mut body = |
| new_body(MirSource::from_instance(instance), blocks, local_decls, sig.inputs().len(), span); |
| |
| if let Abi::RustCall = sig.abi { |
| body.spread_arg = Some(Local::new(sig.inputs().len())); |
| } |
| |
| body |
| } |
| |
| pub fn build_adt_ctor(tcx: TyCtxt<'_>, ctor_id: DefId) -> Body<'_> { |
| debug_assert!(tcx.is_constructor(ctor_id)); |
| |
| let param_env = tcx.param_env_reveal_all_normalized(ctor_id); |
| |
| // Normalize the sig. |
| let sig = tcx |
| .fn_sig(ctor_id) |
| .subst_identity() |
| .no_bound_vars() |
| .expect("LBR in ADT constructor signature"); |
| let sig = tcx.normalize_erasing_regions(param_env, sig); |
| |
| let ty::Adt(adt_def, substs) = sig.output().kind() else { |
| bug!("unexpected type for ADT ctor {:?}", sig.output()); |
| }; |
| |
| debug!("build_ctor: ctor_id={:?} sig={:?}", ctor_id, sig); |
| |
| let span = tcx.def_span(ctor_id); |
| |
| let local_decls = local_decls_for_sig(&sig, span); |
| |
| let source_info = SourceInfo::outermost(span); |
| |
| let variant_index = |
| if adt_def.is_enum() { adt_def.variant_index_with_ctor_id(ctor_id) } else { FIRST_VARIANT }; |
| |
| // Generate the following MIR: |
| // |
| // (return as Variant).field0 = arg0; |
| // (return as Variant).field1 = arg1; |
| // |
| // return; |
| debug!("build_ctor: variant_index={:?}", variant_index); |
| |
| let kind = AggregateKind::Adt(adt_def.did(), variant_index, substs, None, None); |
| let variant = adt_def.variant(variant_index); |
| let statement = Statement { |
| kind: StatementKind::Assign(Box::new(( |
| Place::return_place(), |
| Rvalue::Aggregate( |
| Box::new(kind), |
| (0..variant.fields.len()) |
| .map(|idx| Operand::Move(Place::from(Local::new(idx + 1)))) |
| .collect(), |
| ), |
| ))), |
| source_info, |
| }; |
| |
| let start_block = BasicBlockData { |
| statements: vec![statement], |
| terminator: Some(Terminator { source_info, kind: TerminatorKind::Return }), |
| is_cleanup: false, |
| }; |
| |
| let source = MirSource::item(ctor_id); |
| let body = new_body( |
| source, |
| IndexVec::from_elem_n(start_block, 1), |
| local_decls, |
| sig.inputs().len(), |
| span, |
| ); |
| |
| crate::pass_manager::dump_mir_for_phase_change(tcx, &body); |
| |
| body |
| } |
| |
| /// ```ignore (pseudo-impl) |
| /// impl FnPtr for fn(u32) { |
| /// fn addr(self) -> usize { |
| /// self as usize |
| /// } |
| /// } |
| /// ``` |
| fn build_fn_ptr_addr_shim<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId, self_ty: Ty<'tcx>) -> Body<'tcx> { |
| assert!(matches!(self_ty.kind(), ty::FnPtr(..)), "expected fn ptr, found {self_ty}"); |
| let span = tcx.def_span(def_id); |
| let Some(sig) = tcx.fn_sig(def_id).subst(tcx, &[self_ty.into()]).no_bound_vars() else { |
| span_bug!(span, "FnPtr::addr with bound vars for `{self_ty}`"); |
| }; |
| let locals = local_decls_for_sig(&sig, span); |
| |
| let source_info = SourceInfo::outermost(span); |
| // FIXME: use `expose_addr` once we figure out whether function pointers have meaningful provenance. |
| let rvalue = Rvalue::Cast( |
| CastKind::FnPtrToPtr, |
| Operand::Move(Place::from(Local::new(1))), |
| tcx.mk_imm_ptr(tcx.types.unit), |
| ); |
| let stmt = Statement { |
| source_info, |
| kind: StatementKind::Assign(Box::new((Place::return_place(), rvalue))), |
| }; |
| let statements = vec![stmt]; |
| let start_block = BasicBlockData { |
| statements, |
| terminator: Some(Terminator { source_info, kind: TerminatorKind::Return }), |
| is_cleanup: false, |
| }; |
| let source = MirSource::from_instance(ty::InstanceDef::FnPtrAddrShim(def_id, self_ty)); |
| new_body(source, IndexVec::from_elem_n(start_block, 1), locals, sig.inputs().len(), span) |
| } |
