From 3a19fbf95d3b289f4c17aba910051cd9afd75887 Mon Sep 17 00:00:00 2001 From: Matthew Jasper Date: Sun, 23 Dec 2018 19:00:58 +0000 Subject: [PATCH] Add Rvalue::AddressOf to MIR This operator creates a raw pointer to a Place directly, without first creating a reference. See RFC #2582 for motivation. The Rvalue is currently unused. --- src/librustc/mir/mod.rs | 18 +++ src/librustc/mir/tcx.rs | 7 ++ src/librustc/mir/visit.rs | 16 +++ src/librustc/ty/cast.rs | 3 - src/librustc_codegen_ssa/mir/analyze.rs | 2 + src/librustc_codegen_ssa/mir/place.rs | 2 +- src/librustc_codegen_ssa/mir/rvalue.rs | 58 +++++---- src/librustc_mir/borrow_check/invalidation.rs | 18 ++- src/librustc_mir/borrow_check/mod.rs | 25 ++++ .../borrow_check/type_check/mod.rs | 49 ++------ .../dataflow/move_paths/builder.rs | 1 + src/librustc_mir/interpret/step.rs | 2 +- src/librustc_mir/transform/add_retag.rs | 18 +-- .../transform/check_consts/ops.rs | 17 +++ .../transform/check_consts/qualifs.rs | 18 ++- .../transform/check_consts/validation.rs | 110 +++++++++++------- src/librustc_mir/transform/promote_consts.rs | 24 +++- .../transform/qualify_min_const_fn.rs | 8 +- src/librustc_mir/util/liveness.rs | 2 + src/librustc_typeck/check/cast.rs | 76 ++++++------ 20 files changed, 306 insertions(+), 168 deletions(-) diff --git a/src/librustc/mir/mod.rs b/src/librustc/mir/mod.rs index ba8feb4ee739..3b4adbaf78c7 100644 --- a/src/librustc/mir/mod.rs +++ b/src/librustc/mir/mod.rs @@ -2060,6 +2060,11 @@ pub enum Rvalue<'tcx> { /// &x or &mut x Ref(Region<'tcx>, BorrowKind, Place<'tcx>), + /// Create a raw pointer to the given place + /// Can be generated by raw address of expressions (`&raw const x`), + /// or when casting a reference to a raw pointer. + AddressOf(Mutability, Place<'tcx>), + /// length of a [X] or [X;n] value Len(Place<'tcx>), @@ -2214,6 +2219,15 @@ impl<'tcx> Debug for Rvalue<'tcx> { write!(fmt, "&{}{}{:?}", region, kind_str, place) } + AddressOf(mutability, ref place) => { + let kind_str = match mutability { + Mutability::Mut => "mut", + Mutability::Not => "const", + }; + + write!(fmt, "&raw {} {:?}", kind_str, place) + } + Aggregate(ref kind, ref places) => { fn fmt_tuple(fmt: &mut Formatter<'_>, places: &[Operand<'_>]) -> fmt::Result { let mut tuple_fmt = fmt.debug_tuple(""); @@ -3085,6 +3099,9 @@ impl<'tcx> TypeFoldable<'tcx> for Rvalue<'tcx> { Ref(region, bk, ref place) => { Ref(region.fold_with(folder), bk, place.fold_with(folder)) } + AddressOf(mutability, ref place) => { + AddressOf(mutability, place.fold_with(folder)) + } Len(ref place) => Len(place.fold_with(folder)), Cast(kind, ref op, ty) => Cast(kind, op.fold_with(folder), ty.fold_with(folder)), BinaryOp(op, ref rhs, ref lhs) => { @@ -3125,6 +3142,7 @@ impl<'tcx> TypeFoldable<'tcx> for Rvalue<'tcx> { Use(ref op) => op.visit_with(visitor), Repeat(ref op, _) => op.visit_with(visitor), Ref(region, _, ref place) => region.visit_with(visitor) || place.visit_with(visitor), + AddressOf(_, ref place) => place.visit_with(visitor), Len(ref place) => place.visit_with(visitor), Cast(_, ref op, ty) => op.visit_with(visitor) || ty.visit_with(visitor), BinaryOp(_, ref rhs, ref lhs) | CheckedBinaryOp(_, ref rhs, ref lhs) => { diff --git a/src/librustc/mir/tcx.rs b/src/librustc/mir/tcx.rs index 445fa6ea8cab..a24b1d863d64 100644 --- a/src/librustc/mir/tcx.rs +++ b/src/librustc/mir/tcx.rs @@ -172,6 +172,13 @@ impl<'tcx> Rvalue<'tcx> { } ) } + Rvalue::AddressOf(mutability, ref place) => { + let place_ty = place.ty(local_decls, tcx).ty; + tcx.mk_ptr(ty::TypeAndMut { + ty: place_ty, + mutbl: mutability.into(), + }) + } Rvalue::Len(..) => tcx.types.usize, Rvalue::Cast(.., ty) => ty, Rvalue::BinaryOp(op, ref lhs, ref rhs) => { diff --git a/src/librustc/mir/visit.rs b/src/librustc/mir/visit.rs index 5d273fe85b6d..fa96b51347d3 100644 --- a/src/librustc/mir/visit.rs +++ b/src/librustc/mir/visit.rs @@ -570,6 +570,18 @@ macro_rules! make_mir_visitor { self.visit_place(path, ctx, location); } + Rvalue::AddressOf(m, path) => { + let ctx = match m { + Mutability::Mut => PlaceContext::MutatingUse( + MutatingUseContext::AddressOf + ), + Mutability::Not => PlaceContext::NonMutatingUse( + NonMutatingUseContext::AddressOf + ), + }; + self.visit_place(path, ctx, location); + } + Rvalue::Len(path) => { self.visit_place( path, @@ -1031,6 +1043,8 @@ pub enum NonMutatingUseContext { ShallowBorrow, /// Unique borrow. UniqueBorrow, + /// AddressOf for *const pointer. + AddressOf, /// Used as base for another place, e.g., `x` in `x.y`. Will not mutate the place. /// For example, the projection `x.y` is not marked as a mutation in these cases: /// @@ -1054,6 +1068,8 @@ pub enum MutatingUseContext { Drop, /// Mutable borrow. Borrow, + /// AddressOf for *mut pointer. + AddressOf, /// Used as base for another place, e.g., `x` in `x.y`. Could potentially mutate the place. /// For example, the projection `x.y` is marked as a mutation in these cases: /// diff --git a/src/librustc/ty/cast.rs b/src/librustc/ty/cast.rs index bc12412312de..fca53db1475a 100644 --- a/src/librustc/ty/cast.rs +++ b/src/librustc/ty/cast.rs @@ -28,8 +28,6 @@ pub enum CastTy<'tcx> { FnPtr, /// Raw pointers Ptr(ty::TypeAndMut<'tcx>), - /// References - RPtr(ty::TypeAndMut<'tcx>), } /// Cast Kind. See RFC 401 (or librustc_typeck/check/cast.rs) @@ -63,7 +61,6 @@ impl<'tcx> CastTy<'tcx> { ty::Adt(d,_) if d.is_enum() && d.is_payloadfree() => Some(CastTy::Int(IntTy::CEnum)), ty::RawPtr(mt) => Some(CastTy::Ptr(mt)), - ty::Ref(_, ty, mutbl) => Some(CastTy::RPtr(ty::TypeAndMut { ty, mutbl })), ty::FnPtr(..) => Some(CastTy::FnPtr), _ => None, } diff --git a/src/librustc_codegen_ssa/mir/analyze.rs b/src/librustc_codegen_ssa/mir/analyze.rs index 6c627085b2ed..7bcd98167864 100644 --- a/src/librustc_codegen_ssa/mir/analyze.rs +++ b/src/librustc_codegen_ssa/mir/analyze.rs @@ -340,10 +340,12 @@ impl<'mir, 'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> Visitor<'tcx> PlaceContext::MutatingUse(MutatingUseContext::Store) | PlaceContext::MutatingUse(MutatingUseContext::AsmOutput) | PlaceContext::MutatingUse(MutatingUseContext::Borrow) | + PlaceContext::MutatingUse(MutatingUseContext::AddressOf) | PlaceContext::MutatingUse(MutatingUseContext::Projection) | PlaceContext::NonMutatingUse(NonMutatingUseContext::SharedBorrow) | PlaceContext::NonMutatingUse(NonMutatingUseContext::UniqueBorrow) | PlaceContext::NonMutatingUse(NonMutatingUseContext::ShallowBorrow) | + PlaceContext::NonMutatingUse(NonMutatingUseContext::AddressOf) | PlaceContext::NonMutatingUse(NonMutatingUseContext::Projection) => { self.not_ssa(local); } diff --git a/src/librustc_codegen_ssa/mir/place.rs b/src/librustc_codegen_ssa/mir/place.rs index 5e13cabced00..5b21dfbdf1c6 100644 --- a/src/librustc_codegen_ssa/mir/place.rs +++ b/src/librustc_codegen_ssa/mir/place.rs @@ -448,7 +448,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> { let cx = self.cx; let tcx = self.cx.tcx(); - let result = match &place_ref { + let result = match place_ref { mir::PlaceRef { base: mir::PlaceBase::Local(index), projection: [], diff --git a/src/librustc_codegen_ssa/mir/rvalue.rs b/src/librustc_codegen_ssa/mir/rvalue.rs index 488ae8dbf903..3a8d782aa730 100644 --- a/src/librustc_codegen_ssa/mir/rvalue.rs +++ b/src/librustc_codegen_ssa/mir/rvalue.rs @@ -7,7 +7,7 @@ use crate::MemFlags; use crate::common::{self, RealPredicate, IntPredicate}; use crate::traits::*; -use rustc::ty::{self, Ty, adjustment::{PointerCast}, Instance}; +use rustc::ty::{self, Ty, TyCtxt, adjustment::{PointerCast}, Instance}; use rustc::ty::cast::{CastTy, IntTy}; use rustc::ty::layout::{self, LayoutOf, HasTyCtxt}; use rustc::mir; @@ -342,8 +342,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> { } } (CastTy::Ptr(_), CastTy::Ptr(_)) | - (CastTy::FnPtr, CastTy::Ptr(_)) | - (CastTy::RPtr(_), CastTy::Ptr(_)) => + (CastTy::FnPtr, CastTy::Ptr(_)) => bx.pointercast(llval, ll_t_out), (CastTy::Ptr(_), CastTy::Int(_)) | (CastTy::FnPtr, CastTy::Int(_)) => @@ -370,24 +369,18 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> { } mir::Rvalue::Ref(_, bk, ref place) => { - let cg_place = self.codegen_place(&mut bx, &place.as_ref()); + let mk_ref = move |tcx: TyCtxt<'tcx>, ty: Ty<'tcx>| tcx.mk_ref( + tcx.lifetimes.re_erased, + ty::TypeAndMut { ty, mutbl: bk.to_mutbl_lossy() } + ); + self.codegen_place_to_pointer(bx, place, mk_ref) + } - let ty = cg_place.layout.ty; - - // Note: places are indirect, so storing the `llval` into the - // destination effectively creates a reference. - let val = if !bx.cx().type_has_metadata(ty) { - OperandValue::Immediate(cg_place.llval) - } else { - OperandValue::Pair(cg_place.llval, cg_place.llextra.unwrap()) - }; - (bx, OperandRef { - val, - layout: self.cx.layout_of(self.cx.tcx().mk_ref( - self.cx.tcx().lifetimes.re_erased, - ty::TypeAndMut { ty, mutbl: bk.to_mutbl_lossy() } - )), - }) + mir::Rvalue::AddressOf(mutability, ref place) => { + let mk_ptr = move |tcx: TyCtxt<'tcx>, ty: Ty<'tcx>| tcx.mk_ptr( + ty::TypeAndMut { ty, mutbl: mutability.into() } + ); + self.codegen_place_to_pointer(bx, place, mk_ptr) } mir::Rvalue::Len(ref place) => { @@ -543,6 +536,30 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> { cg_value.len(bx.cx()) } + /// Codegen an `Rvalue::AddressOf` or `Rvalue::Ref` + fn codegen_place_to_pointer( + &mut self, + mut bx: Bx, + place: &mir::Place<'tcx>, + mk_ptr_ty: impl FnOnce(TyCtxt<'tcx>, Ty<'tcx>) -> Ty<'tcx>, + ) -> (Bx, OperandRef<'tcx, Bx::Value>) { + let cg_place = self.codegen_place(&mut bx, &place.as_ref()); + + let ty = cg_place.layout.ty; + + // Note: places are indirect, so storing the `llval` into the + // destination effectively creates a reference. + let val = if !bx.cx().type_has_metadata(ty) { + OperandValue::Immediate(cg_place.llval) + } else { + OperandValue::Pair(cg_place.llval, cg_place.llextra.unwrap()) + }; + (bx, OperandRef { + val, + layout: self.cx.layout_of(mk_ptr_ty(self.cx.tcx(), ty)), + }) + } + pub fn codegen_scalar_binop( &mut self, bx: &mut Bx, @@ -699,6 +716,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> { pub fn rvalue_creates_operand(&self, rvalue: &mir::Rvalue<'tcx>, span: Span) -> bool { match *rvalue { mir::Rvalue::Ref(..) | + mir::Rvalue::AddressOf(..) | mir::Rvalue::Len(..) | mir::Rvalue::Cast(..) | // (*) mir::Rvalue::BinaryOp(..) | diff --git a/src/librustc_mir/borrow_check/invalidation.rs b/src/librustc_mir/borrow_check/invalidation.rs index 58fac5512d9b..d5b9aaf9511a 100644 --- a/src/librustc_mir/borrow_check/invalidation.rs +++ b/src/librustc_mir/borrow_check/invalidation.rs @@ -3,7 +3,7 @@ use rustc::mir::visit::Visitor; use rustc::mir::{BasicBlock, Location, Body, Place, ReadOnlyBodyAndCache, Rvalue}; use rustc::mir::{Statement, StatementKind}; use rustc::mir::TerminatorKind; -use rustc::mir::{Operand, BorrowKind}; +use rustc::mir::{Operand, BorrowKind, Mutability}; use rustc_data_structures::graph::dominators::Dominators; use crate::dataflow::indexes::BorrowIndex; @@ -337,6 +337,22 @@ impl<'cx, 'tcx> InvalidationGenerator<'cx, 'tcx> { ); } + Rvalue::AddressOf(mutability, ref place) => { + let access_kind = match mutability { + Mutability::Mut => (Deep, Write(WriteKind::MutableBorrow(BorrowKind::Mut { + allow_two_phase_borrow: false, + }))), + Mutability::Not => (Deep, Read(ReadKind::Borrow(BorrowKind::Shared))), + }; + + self.access_place( + location, + place, + access_kind, + LocalMutationIsAllowed::No, + ); + } + Rvalue::Use(ref operand) | Rvalue::Repeat(ref operand, _) | Rvalue::UnaryOp(_ /*un_op*/, ref operand) diff --git a/src/librustc_mir/borrow_check/mod.rs b/src/librustc_mir/borrow_check/mod.rs index 11012ef2fc7e..2554d5e729da 100644 --- a/src/librustc_mir/borrow_check/mod.rs +++ b/src/librustc_mir/borrow_check/mod.rs @@ -1233,6 +1233,31 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> { ); } + + Rvalue::AddressOf(mutability, ref place) => { + let access_kind = match mutability { + Mutability::Mut => (Deep, Write(WriteKind::MutableBorrow(BorrowKind::Mut { + allow_two_phase_borrow: false, + }))), + Mutability::Not => (Deep, Read(ReadKind::Borrow(BorrowKind::Shared))), + }; + + self.access_place( + location, + (place, span), + access_kind, + LocalMutationIsAllowed::No, + flow_state, + ); + + self.check_if_path_or_subpath_is_moved( + location, + InitializationRequiringAction::Borrow, + (place.as_ref(), span), + flow_state, + ); + } + Rvalue::Use(ref operand) | Rvalue::Repeat(ref operand, _) | Rvalue::UnaryOp(_ /*un_op*/, ref operand) diff --git a/src/librustc_mir/borrow_check/type_check/mod.rs b/src/librustc_mir/borrow_check/type_check/mod.rs index 663536bc2b4b..108279eeef49 100644 --- a/src/librustc_mir/borrow_check/type_check/mod.rs +++ b/src/librustc_mir/borrow_check/type_check/mod.rs @@ -2273,41 +2273,6 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> { let cast_ty_from = CastTy::from_ty(ty_from); let cast_ty_to = CastTy::from_ty(ty); match (cast_ty_from, cast_ty_to) { - (Some(CastTy::RPtr(ref_tm)), Some(CastTy::Ptr(ptr_tm))) => { - if let hir::Mutability::Mutable = ptr_tm.mutbl { - if let Err(terr) = self.eq_types( - ref_tm.ty, - ptr_tm.ty, - location.to_locations(), - ConstraintCategory::Cast, - ) { - span_mirbug!( - self, - rvalue, - "equating {:?} with {:?} yields {:?}", - ref_tm.ty, - ptr_tm.ty, - terr - ) - } - } else { - if let Err(terr) = self.sub_types( - ref_tm.ty, - ptr_tm.ty, - location.to_locations(), - ConstraintCategory::Cast, - ) { - span_mirbug!( - self, - rvalue, - "relating {:?} with {:?} yields {:?}", - ref_tm.ty, - ptr_tm.ty, - terr - ) - } - } - }, (None, _) | (_, None) | (_, Some(CastTy::FnPtr)) @@ -2320,7 +2285,15 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> { ty_from, ty, ), - _ => (), + (Some(CastTy::Int(_)), Some(CastTy::Int(_))) + | (Some(CastTy::Float), Some(CastTy::Int(_))) + | (Some(CastTy::Int(_)), Some(CastTy::Float)) + | (Some(CastTy::Float), Some(CastTy::Float)) + | (Some(CastTy::Ptr(_)), Some(CastTy::Int(_))) + | (Some(CastTy::FnPtr), Some(CastTy::Int(_))) + | (Some(CastTy::Int(_)), Some(CastTy::Ptr(_))) + | (Some(CastTy::Ptr(_)), Some(CastTy::Ptr(_))) + | (Some(CastTy::FnPtr), Some(CastTy::Ptr(_))) => (), } } } @@ -2371,7 +2344,8 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> { } } - Rvalue::Use(..) + Rvalue::AddressOf(..) + | Rvalue::Use(..) | Rvalue::Len(..) | Rvalue::BinaryOp(..) | Rvalue::CheckedBinaryOp(..) @@ -2388,6 +2362,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> { Rvalue::Use(_) | Rvalue::Repeat(..) | Rvalue::Ref(..) + | Rvalue::AddressOf(..) | Rvalue::Len(..) | Rvalue::Cast(..) | Rvalue::BinaryOp(..) diff --git a/src/librustc_mir/dataflow/move_paths/builder.rs b/src/librustc_mir/dataflow/move_paths/builder.rs index fa0864e0de76..5522da6fbf08 100644 --- a/src/librustc_mir/dataflow/move_paths/builder.rs +++ b/src/librustc_mir/dataflow/move_paths/builder.rs @@ -335,6 +335,7 @@ impl<'b, 'a, 'tcx> Gatherer<'b, 'a, 'tcx> { } } Rvalue::Ref(..) + | Rvalue::AddressOf(..) | Rvalue::Discriminant(..) | Rvalue::Len(..) | Rvalue::NullaryOp(NullOp::SizeOf, _) diff --git a/src/librustc_mir/interpret/step.rs b/src/librustc_mir/interpret/step.rs index 33ed69af6ba0..33cdf1b27f8d 100644 --- a/src/librustc_mir/interpret/step.rs +++ b/src/librustc_mir/interpret/step.rs @@ -248,7 +248,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> { )?; } - Ref(_, _, ref place) => { + AddressOf(_, ref place) | Ref(_, _, ref place) => { let src = self.eval_place(place)?; let place = self.force_allocation(src)?; if place.layout.size.bytes() > 0 { diff --git a/src/librustc_mir/transform/add_retag.rs b/src/librustc_mir/transform/add_retag.rs index dc21c674eea2..0e4fe3f7f401 100644 --- a/src/librustc_mir/transform/add_retag.rs +++ b/src/librustc_mir/transform/add_retag.rs @@ -136,21 +136,9 @@ impl<'tcx> MirPass<'tcx> for AddRetag { // iterate backwards using indices. for i in (0..block_data.statements.len()).rev() { let (retag_kind, place) = match block_data.statements[i].kind { - // If we are casting *from* a reference, we may have to retag-as-raw. - StatementKind::Assign(box(ref place, Rvalue::Cast( - CastKind::Misc, - ref src, - dest_ty, - ))) => { - let src_ty = src.ty(&*local_decls, tcx); - if src_ty.is_region_ptr() { - // The only `Misc` casts on references are those creating raw pointers. - assert!(dest_ty.is_unsafe_ptr()); - (RetagKind::Raw, place.clone()) - } else { - // Some other cast, no retag - continue - } + // Retag-as-raw after escaping to a raw pointer. + StatementKind::Assign(box (ref place, Rvalue::AddressOf(..))) => { + (RetagKind::Raw, place.clone()) } // Assignments of reference or ptr type are the ones where we may have // to update tags. This includes `x = &[mut] ...` and hence diff --git a/src/librustc_mir/transform/check_consts/ops.rs b/src/librustc_mir/transform/check_consts/ops.rs index 3df60993d9ad..e5f3003cd711 100644 --- a/src/librustc_mir/transform/check_consts/ops.rs +++ b/src/librustc_mir/transform/check_consts/ops.rs @@ -224,6 +224,23 @@ impl NonConstOp for MutBorrow { } } +#[derive(Debug)] +pub struct MutAddressOf; +impl NonConstOp for MutAddressOf { + fn feature_gate(tcx: TyCtxt<'_>) -> Option { + Some(tcx.features().const_mut_refs) + } + + fn emit_error(&self, item: &Item<'_, '_>, span: Span) { + feature_err( + &item.tcx.sess.parse_sess, + sym::const_mut_refs, + span, + &format!("`&raw mut` is not allowed in {}s", item.const_kind()) + ).emit(); + } +} + #[derive(Debug)] pub struct MutDeref; impl NonConstOp for MutDeref { diff --git a/src/librustc_mir/transform/check_consts/qualifs.rs b/src/librustc_mir/transform/check_consts/qualifs.rs index 223a5f8d605f..28243bd71a22 100644 --- a/src/librustc_mir/transform/check_consts/qualifs.rs +++ b/src/librustc_mir/transform/check_consts/qualifs.rs @@ -151,17 +151,15 @@ pub trait Qualif { Self::in_operand(cx, per_local, lhs) || Self::in_operand(cx, per_local, rhs) } - Rvalue::Ref(_, _, ref place) => { + Rvalue::Ref(_, _, ref place) | Rvalue::AddressOf(_, ref place) => { // Special-case reborrows to be more like a copy of the reference. - if let &[ref proj_base @ .., elem] = place.projection.as_ref() { - if ProjectionElem::Deref == elem { - let base_ty = Place::ty_from(&place.base, proj_base, *cx.body, cx.tcx).ty; - if let ty::Ref(..) = base_ty.kind { - return Self::in_place(cx, per_local, PlaceRef { - base: &place.base, - projection: proj_base, - }); - } + if let [proj_base @ .., ProjectionElem::Deref] = place.projection.as_ref() { + let base_ty = Place::ty_from(&place.base, proj_base, *cx.body, cx.tcx).ty; + if let ty::Ref(..) = base_ty.kind { + return Self::in_place(cx, per_local, PlaceRef { + base: &place.base, + projection: proj_base, + }); } } diff --git a/src/librustc_mir/transform/check_consts/validation.rs b/src/librustc_mir/transform/check_consts/validation.rs index 6261315c711c..0904264586c7 100644 --- a/src/librustc_mir/transform/check_consts/validation.rs +++ b/src/librustc_mir/transform/check_consts/validation.rs @@ -276,6 +276,27 @@ impl Validator<'a, 'mir, 'tcx> { self.check_op_spanned(ops::StaticAccess, span) } } + + fn check_immutable_borrow_like( + &mut self, + location: Location, + place: &Place<'tcx>, + ) { + // FIXME: Change the `in_*` methods to take a `FnMut` so we don't have to manually + // seek the cursors beforehand. + self.qualifs.has_mut_interior.cursor.seek_before(location); + self.qualifs.indirectly_mutable.seek(location); + + let borrowed_place_has_mut_interior = HasMutInterior::in_place( + &self.item, + &|local| self.qualifs.has_mut_interior_eager_seek(local), + place.as_ref(), + ); + + if borrowed_place_has_mut_interior { + self.check_op(ops::CellBorrow); + } + } } impl Visitor<'tcx> for Validator<'_, 'mir, 'tcx> { @@ -302,26 +323,44 @@ impl Visitor<'tcx> for Validator<'_, 'mir, 'tcx> { trace!("visit_rvalue: rvalue={:?} location={:?}", rvalue, location); // Special-case reborrows to be more like a copy of a reference. - if let Rvalue::Ref(_, kind, ref place) = *rvalue { - if let Some(reborrowed_proj) = place_as_reborrow(self.tcx, *self.body, place) { - let ctx = match kind { - BorrowKind::Shared => PlaceContext::NonMutatingUse( - NonMutatingUseContext::SharedBorrow, - ), - BorrowKind::Shallow => PlaceContext::NonMutatingUse( - NonMutatingUseContext::ShallowBorrow, - ), - BorrowKind::Unique => PlaceContext::NonMutatingUse( - NonMutatingUseContext::UniqueBorrow, - ), - BorrowKind::Mut { .. } => PlaceContext::MutatingUse( - MutatingUseContext::Borrow, - ), - }; - self.visit_place_base(&place.base, ctx, location); - self.visit_projection(&place.base, reborrowed_proj, ctx, location); - return; + match *rvalue { + Rvalue::Ref(_, kind, ref place) => { + if let Some(reborrowed_proj) = place_as_reborrow(self.tcx, *self.body, place) { + let ctx = match kind { + BorrowKind::Shared => PlaceContext::NonMutatingUse( + NonMutatingUseContext::SharedBorrow, + ), + BorrowKind::Shallow => PlaceContext::NonMutatingUse( + NonMutatingUseContext::ShallowBorrow, + ), + BorrowKind::Unique => PlaceContext::NonMutatingUse( + NonMutatingUseContext::UniqueBorrow, + ), + BorrowKind::Mut { .. } => PlaceContext::MutatingUse( + MutatingUseContext::Borrow, + ), + }; + self.visit_place_base(&place.base, ctx, location); + self.visit_projection(&place.base, reborrowed_proj, ctx, location); + return; + } } + Rvalue::AddressOf(mutbl, ref place) => { + if let Some(reborrowed_proj) = place_as_reborrow(self.tcx, *self.body, place) { + let ctx = match mutbl { + Mutability::Not => PlaceContext::NonMutatingUse( + NonMutatingUseContext::AddressOf, + ), + Mutability::Mut => PlaceContext::MutatingUse( + MutatingUseContext::AddressOf, + ), + }; + self.visit_place_base(&place.base, ctx, location); + self.visit_projection(&place.base, reborrowed_proj, ctx, location); + return; + } + } + _ => {} } self.super_rvalue(rvalue, location); @@ -367,34 +406,25 @@ impl Visitor<'tcx> for Validator<'_, 'mir, 'tcx> { } } + Rvalue::AddressOf(Mutability::Mut, _) => { + self.check_op(ops::MutAddressOf) + } + // At the moment, `PlaceBase::Static` is only used for promoted MIR. | Rvalue::Ref(_, BorrowKind::Shared, ref place) | Rvalue::Ref(_, BorrowKind::Shallow, ref place) + | Rvalue::AddressOf(Mutability::Not, ref place) if matches!(place.base, PlaceBase::Static(_)) => bug!("Saw a promoted during const-checking, which must run before promotion"), - | Rvalue::Ref(_, kind @ BorrowKind::Shared, ref place) - | Rvalue::Ref(_, kind @ BorrowKind::Shallow, ref place) - => { - // FIXME: Change the `in_*` methods to take a `FnMut` so we don't have to manually - // seek the cursors beforehand. - self.qualifs.has_mut_interior.cursor.seek_before(location); - self.qualifs.indirectly_mutable.seek(location); + | Rvalue::Ref(_, BorrowKind::Shared, ref place) + | Rvalue::Ref(_, BorrowKind::Shallow, ref place) => { + self.check_immutable_borrow_like(location, place) + }, - let borrowed_place_has_mut_interior = HasMutInterior::in_place( - &self.item, - &|local| self.qualifs.has_mut_interior_eager_seek(local), - place.as_ref(), - ); - - if borrowed_place_has_mut_interior { - if let BorrowKind::Mut{ .. } = kind { - self.check_op(ops::MutBorrow); - } else { - self.check_op(ops::CellBorrow); - } - } - } + Rvalue::AddressOf(Mutability::Not, ref place) => { + self.check_immutable_borrow_like(location, place) + }, Rvalue::Cast(CastKind::Misc, ref operand, cast_ty) => { let operand_ty = operand.ty(*self.body, self.tcx); diff --git a/src/librustc_mir/transform/promote_consts.rs b/src/librustc_mir/transform/promote_consts.rs index 4c723199102b..4e5d8ae08fe5 100644 --- a/src/librustc_mir/transform/promote_consts.rs +++ b/src/librustc_mir/transform/promote_consts.rs @@ -196,7 +196,12 @@ impl<'tcx> Visitor<'tcx> for Collector<'_, 'tcx> { } else if let TempState::Defined { ref mut uses, .. } = *temp { // We always allow borrows, even mutable ones, as we need // to promote mutable borrows of some ZSTs e.g., `&mut []`. - let allowed_use = context.is_borrow() || context.is_nonmutating_use(); + let allowed_use = match context { + PlaceContext::MutatingUse(MutatingUseContext::Borrow) + | PlaceContext::NonMutatingUse(_) => true, + PlaceContext::MutatingUse(_) + | PlaceContext::NonUse(_) => false, + }; debug!("visit_local: allowed_use={:?}", allowed_use); if allowed_use { *uses += 1; @@ -618,6 +623,21 @@ impl<'tcx> Validator<'_, 'tcx> { self.validate_operand(rhs) } + Rvalue::AddressOf(_, place) => { + // Raw reborrows can come from reference to pointer coercions, + // so are allowed. + if let [proj_base @ .., ProjectionElem::Deref] = place.projection.as_ref() { + let base_ty = Place::ty_from(&place.base, proj_base, *self.body, self.tcx).ty; + if let ty::Ref(..) = base_ty.kind { + return self.validate_place(PlaceRef { + base: &place.base, + projection: proj_base, + }); + } + } + Err(Unpromotable) + } + Rvalue::Ref(_, kind, place) => { if let BorrowKind::Mut { .. } = kind { let ty = place.ty(*self.body, self.tcx).ty; @@ -950,7 +970,7 @@ impl<'a, 'tcx> Promoter<'a, 'tcx> { Candidate::Ref(loc) => { let ref mut statement = blocks[loc.block].statements[loc.statement_index]; match statement.kind { - StatementKind::Assign(box(_, Rvalue::Ref(_, _, ref mut place))) => { + StatementKind::Assign(box (_, Rvalue::Ref(_, _, ref mut place))) => { // Use the underlying local for this (necessarily interior) borrow. let ty = place.base.ty(local_decls).ty; let span = statement.source_info.span; diff --git a/src/librustc_mir/transform/qualify_min_const_fn.rs b/src/librustc_mir/transform/qualify_min_const_fn.rs index e2530795749a..a61bff37fc87 100644 --- a/src/librustc_mir/transform/qualify_min_const_fn.rs +++ b/src/librustc_mir/transform/qualify_min_const_fn.rs @@ -135,7 +135,10 @@ fn check_rvalue( Rvalue::Repeat(operand, _) | Rvalue::Use(operand) => { check_operand(tcx, operand, span, def_id, body) } - Rvalue::Len(place) | Rvalue::Discriminant(place) | Rvalue::Ref(_, _, place) => { + Rvalue::Len(place) + | Rvalue::Discriminant(place) + | Rvalue::Ref(_, _, place) + | Rvalue::AddressOf(_, place) => { check_place(tcx, place, span, def_id, body) } Rvalue::Cast(CastKind::Misc, operand, cast_ty) => { @@ -147,9 +150,6 @@ fn check_rvalue( span, "casting pointers to ints is unstable in const fn".into(), )), - (CastTy::RPtr(_), CastTy::Float) => bug!(), - (CastTy::RPtr(_), CastTy::Int(_)) => bug!(), - (CastTy::Ptr(_), CastTy::RPtr(_)) => bug!(), _ => check_operand(tcx, operand, span, def_id, body), } } diff --git a/src/librustc_mir/util/liveness.rs b/src/librustc_mir/util/liveness.rs index 68c2e16399a5..01eebeb8c55a 100644 --- a/src/librustc_mir/util/liveness.rs +++ b/src/librustc_mir/util/liveness.rs @@ -167,6 +167,8 @@ pub fn categorize(context: PlaceContext) -> Option { PlaceContext::NonMutatingUse(NonMutatingUseContext::ShallowBorrow) | PlaceContext::NonMutatingUse(NonMutatingUseContext::UniqueBorrow) | + PlaceContext::MutatingUse(MutatingUseContext::AddressOf) | + PlaceContext::NonMutatingUse(NonMutatingUseContext::AddressOf) | PlaceContext::NonMutatingUse(NonMutatingUseContext::Inspect) | PlaceContext::NonMutatingUse(NonMutatingUseContext::Copy) | PlaceContext::NonMutatingUse(NonMutatingUseContext::Move) | diff --git a/src/librustc_typeck/check/cast.rs b/src/librustc_typeck/check/cast.rs index 035ece238104..21ba02746c79 100644 --- a/src/librustc_typeck/check/cast.rs +++ b/src/librustc_typeck/check/cast.rs @@ -469,22 +469,48 @@ impl<'a, 'tcx> CastCheck<'tcx> { (Some(t_from), Some(t_cast)) => (t_from, t_cast), // Function item types may need to be reified before casts. (None, Some(t_cast)) => { - if let ty::FnDef(..) = self.expr_ty.kind { - // Attempt a coercion to a fn pointer type. - let f = self.expr_ty.fn_sig(fcx.tcx); - let res = fcx.try_coerce(self.expr, - self.expr_ty, - fcx.tcx.mk_fn_ptr(f), - AllowTwoPhase::No); - if let Err(TypeError::IntrinsicCast) = res { - return Err(CastError::IllegalCast); + match self.expr_ty.kind { + ty::FnDef(..) => { + // Attempt a coercion to a fn pointer type. + let f = self.expr_ty.fn_sig(fcx.tcx); + let res = fcx.try_coerce(self.expr, + self.expr_ty, + fcx.tcx.mk_fn_ptr(f), + AllowTwoPhase::No); + if let Err(TypeError::IntrinsicCast) = res { + return Err(CastError::IllegalCast); + } + if res.is_err() { + return Err(CastError::NonScalar); + } + (FnPtr, t_cast) } - if res.is_err() { - return Err(CastError::NonScalar); + // Special case some errors for references, and check for + // array-ptr-casts. `Ref` is not a CastTy because the cast + // is split into a coercion to a pointer type, followed by + // a cast. + ty::Ref(_, inner_ty, mutbl) => { + return match t_cast { + Int(_) | Float => match inner_ty.kind { + ty::Int(_) | + ty::Uint(_) | + ty::Float(_) | + ty::Infer(ty::InferTy::IntVar(_)) | + ty::Infer(ty::InferTy::FloatVar(_)) => { + Err(CastError::NeedDeref) + } + _ => Err(CastError::NeedViaPtr), + } + // array-ptr-cast + Ptr(mt) => self.check_ref_cast( + fcx, + TypeAndMut { mutbl, ty: inner_ty }, + mt, + ), + _ => Err(CastError::NonScalar), + }; } - (FnPtr, t_cast) - } else { - return Err(CastError::NonScalar); + _ => return Err(CastError::NonScalar), } } _ => return Err(CastError::NonScalar), @@ -492,7 +518,7 @@ impl<'a, 'tcx> CastCheck<'tcx> { match (t_from, t_cast) { // These types have invariants! can't cast into them. - (_, RPtr(_)) | (_, Int(CEnum)) | (_, FnPtr) => Err(CastError::NonScalar), + (_, Int(CEnum)) | (_, FnPtr) => Err(CastError::NonScalar), // * -> Bool (_, Int(Bool)) => Err(CastError::CastToBool), @@ -517,28 +543,10 @@ impl<'a, 'tcx> CastCheck<'tcx> { (Ptr(m_e), Ptr(m_c)) => self.check_ptr_ptr_cast(fcx, m_e, m_c), // ptr-ptr-cast (Ptr(m_expr), Int(_)) => self.check_ptr_addr_cast(fcx, m_expr), // ptr-addr-cast (FnPtr, Int(_)) => Ok(CastKind::FnPtrAddrCast), - (RPtr(p), Int(_)) | - (RPtr(p), Float) => { - match p.ty.kind { - ty::Int(_) | - ty::Uint(_) | - ty::Float(_) => { - Err(CastError::NeedDeref) - } - ty::Infer(t) => { - match t { - ty::InferTy::IntVar(_) | - ty::InferTy::FloatVar(_) => Err(CastError::NeedDeref), - _ => Err(CastError::NeedViaPtr), - } - } - _ => Err(CastError::NeedViaPtr), - } - } + // * -> ptr (Int(_), Ptr(mt)) => self.check_addr_ptr_cast(fcx, mt), // addr-ptr-cast (FnPtr, Ptr(mt)) => self.check_fptr_ptr_cast(fcx, mt), - (RPtr(rmt), Ptr(mt)) => self.check_ref_cast(fcx, rmt, mt), // array-ptr-cast // prim -> prim (Int(CEnum), Int(_)) => Ok(CastKind::EnumCast),