diff options
Diffstat (limited to 'compiler/rustc_const_eval/src/interpret/place.rs')
| -rw-r--r-- | compiler/rustc_const_eval/src/interpret/place.rs | 356 |
1 files changed, 240 insertions, 116 deletions
diff --git a/compiler/rustc_const_eval/src/interpret/place.rs b/compiler/rustc_const_eval/src/interpret/place.rs index a9b2b43f1e6..db1239c7136 100644 --- a/compiler/rustc_const_eval/src/interpret/place.rs +++ b/compiler/rustc_const_eval/src/interpret/place.rs @@ -2,11 +2,14 @@ //! into a place. //! All high-level functions to write to memory work on places as destinations. +use std::assert_matches::assert_matches; + use either::{Either, Left, Right}; use rustc_ast::Mutability; use rustc_index::IndexSlice; use rustc_middle::mir; +use rustc_middle::mir::interpret::PointerArithmetic; use rustc_middle::ty; use rustc_middle::ty::layout::{LayoutOf, TyAndLayout}; use rustc_middle::ty::Ty; @@ -15,7 +18,7 @@ use rustc_target::abi::{self, Abi, Align, FieldIdx, HasDataLayout, Size, FIRST_V use super::{ alloc_range, mir_assign_valid_types, AllocId, AllocRef, AllocRefMut, CheckInAllocMsg, ConstAlloc, ImmTy, Immediate, InterpCx, InterpResult, Machine, MemoryKind, OpTy, Operand, - Pointer, Provenance, Scalar, + Pointer, Projectable, Provenance, Scalar, }; #[derive(Copy, Clone, Hash, PartialEq, Eq, Debug)] @@ -44,6 +47,27 @@ impl<Prov: Provenance> MemPlaceMeta<Prov> { Self::None => false, } } + + pub(crate) fn len<'tcx>( + &self, + layout: TyAndLayout<'tcx>, + cx: &impl HasDataLayout, + ) -> InterpResult<'tcx, u64> { + if layout.is_unsized() { + // We need to consult `meta` metadata + match layout.ty.kind() { + ty::Slice(..) | ty::Str => self.unwrap_meta().to_target_usize(cx), + _ => bug!("len not supported on unsized type {:?}", layout.ty), + } + } else { + // Go through the layout. There are lots of types that support a length, + // e.g., SIMD types. (But not all repr(simd) types even have FieldsShape::Array!) + match layout.fields { + abi::FieldsShape::Array { count, .. } => Ok(count), + _ => bug!("len not supported on sized type {:?}", layout.ty), + } + } + } } #[derive(Copy, Clone, Hash, PartialEq, Eq, Debug)] @@ -73,9 +97,13 @@ pub enum Place<Prov: Provenance = AllocId> { /// A place referring to a value allocated in the `Memory` system. Ptr(MemPlace<Prov>), - /// To support alloc-free locals, we are able to write directly to a local. + /// To support alloc-free locals, we are able to write directly to a local. The offset indicates + /// where in the local this place is located; if it is `None`, no projection has been applied. + /// Such projections are meaningful even if the offset is 0, since they can change layouts. /// (Without that optimization, we'd just always be a `MemPlace`.) - Local { frame: usize, local: mir::Local }, + /// Note that this only stores the frame index, not the thread this frame belongs to -- that is + /// implicit. This means a `Place` must never be moved across interpreter thread boundaries! + Local { frame: usize, local: mir::Local, offset: Option<Size> }, } #[derive(Clone, Debug)] @@ -132,6 +160,11 @@ impl<Prov: Provenance> MemPlace<Prov> { MemPlace { ptr, meta: MemPlaceMeta::None } } + #[inline(always)] + pub fn from_ptr_with_meta(ptr: Pointer<Option<Prov>>, meta: MemPlaceMeta<Prov>) -> Self { + MemPlace { ptr, meta } + } + /// Adjust the provenance of the main pointer (metadata is unaffected). pub fn map_provenance(self, f: impl FnOnce(Option<Prov>) -> Option<Prov>) -> Self { MemPlace { ptr: self.ptr.map_provenance(f), ..self } @@ -150,7 +183,8 @@ impl<Prov: Provenance> MemPlace<Prov> { } #[inline] - pub(super) fn offset_with_meta<'tcx>( + // Not called `offset_with_meta` to avoid confusion with the trait method. + fn offset_with_meta_<'tcx>( self, offset: Size, meta: MemPlaceMeta<Prov>, @@ -164,19 +198,6 @@ impl<Prov: Provenance> MemPlace<Prov> { } } -impl<Prov: Provenance> Place<Prov> { - /// Asserts that this points to some local variable. - /// Returns the frame idx and the variable idx. - #[inline] - #[cfg_attr(debug_assertions, track_caller)] // only in debug builds due to perf (see #98980) - pub fn assert_local(&self) -> (usize, mir::Local) { - match self { - Place::Local { frame, local } => (*frame, *local), - _ => bug!("assert_local: expected Place::Local, got {:?}", self), - } - } -} - impl<'tcx, Prov: Provenance> MPlaceTy<'tcx, Prov> { /// Produces a MemPlace that works for ZST but nothing else. /// Conceptually this is a new allocation, but it doesn't actually create an allocation so you @@ -189,37 +210,6 @@ impl<'tcx, Prov: Provenance> MPlaceTy<'tcx, Prov> { MPlaceTy { mplace: MemPlace { ptr, meta: MemPlaceMeta::None }, layout, align } } - /// Offset the place in memory and change its metadata. - /// - /// This can go wrong very easily if you give the wrong layout for the new place! - #[inline] - pub(crate) fn offset_with_meta( - &self, - offset: Size, - meta: MemPlaceMeta<Prov>, - layout: TyAndLayout<'tcx>, - cx: &impl HasDataLayout, - ) -> InterpResult<'tcx, Self> { - Ok(MPlaceTy { - mplace: self.mplace.offset_with_meta(offset, meta, cx)?, - align: self.align.restrict_for_offset(offset), - layout, - }) - } - - /// Offset the place in memory. - /// - /// This can go wrong very easily if you give the wrong layout for the new place! - pub fn offset( - &self, - offset: Size, - layout: TyAndLayout<'tcx>, - cx: &impl HasDataLayout, - ) -> InterpResult<'tcx, Self> { - assert!(layout.is_sized()); - self.offset_with_meta(offset, MemPlaceMeta::None, layout, cx) - } - #[inline] pub fn from_aligned_ptr(ptr: Pointer<Option<Prov>>, layout: TyAndLayout<'tcx>) -> Self { MPlaceTy { mplace: MemPlace::from_ptr(ptr), layout, align: layout.align.abi } @@ -231,28 +221,48 @@ impl<'tcx, Prov: Provenance> MPlaceTy<'tcx, Prov> { layout: TyAndLayout<'tcx>, meta: MemPlaceMeta<Prov>, ) -> Self { - let mut mplace = MemPlace::from_ptr(ptr); - mplace.meta = meta; + MPlaceTy { + mplace: MemPlace::from_ptr_with_meta(ptr, meta), + layout, + align: layout.align.abi, + } + } +} - MPlaceTy { mplace, layout, align: layout.align.abi } +impl<'mir, 'tcx: 'mir, Prov: Provenance + 'static> Projectable<'mir, 'tcx, Prov> + for MPlaceTy<'tcx, Prov> +{ + #[inline(always)] + fn layout(&self) -> TyAndLayout<'tcx> { + self.layout } - #[inline] - pub(crate) fn len(&self, cx: &impl HasDataLayout) -> InterpResult<'tcx, u64> { - if self.layout.is_unsized() { - // We need to consult `meta` metadata - match self.layout.ty.kind() { - ty::Slice(..) | ty::Str => self.mplace.meta.unwrap_meta().to_target_usize(cx), - _ => bug!("len not supported on unsized type {:?}", self.layout.ty), - } - } else { - // Go through the layout. There are lots of types that support a length, - // e.g., SIMD types. (But not all repr(simd) types even have FieldsShape::Array!) - match self.layout.fields { - abi::FieldsShape::Array { count, .. } => Ok(count), - _ => bug!("len not supported on sized type {:?}", self.layout.ty), - } - } + fn meta<M: Machine<'mir, 'tcx, Provenance = Prov>>( + &self, + _ecx: &InterpCx<'mir, 'tcx, M>, + ) -> InterpResult<'tcx, MemPlaceMeta<M::Provenance>> { + Ok(self.meta) + } + + fn offset_with_meta( + &self, + offset: Size, + meta: MemPlaceMeta<Prov>, + layout: TyAndLayout<'tcx>, + cx: &impl HasDataLayout, + ) -> InterpResult<'tcx, Self> { + Ok(MPlaceTy { + mplace: self.mplace.offset_with_meta_(offset, meta, cx)?, + align: self.align.restrict_for_offset(offset), + layout, + }) + } + + fn to_op<M: Machine<'mir, 'tcx, Provenance = Prov>>( + &self, + _ecx: &InterpCx<'mir, 'tcx, M>, + ) -> InterpResult<'tcx, OpTy<'tcx, M::Provenance>> { + Ok(self.into()) } } @@ -280,13 +290,15 @@ impl<'tcx, Prov: Provenance> OpTy<'tcx, Prov> { } } -impl<'tcx, Prov: Provenance> PlaceTy<'tcx, Prov> { +impl<'tcx, Prov: Provenance + 'static> PlaceTy<'tcx, Prov> { /// A place is either an mplace or some local. #[inline] - pub fn as_mplace_or_local(&self) -> Either<MPlaceTy<'tcx, Prov>, (usize, mir::Local)> { + pub fn as_mplace_or_local( + &self, + ) -> Either<MPlaceTy<'tcx, Prov>, (usize, mir::Local, Option<Size>)> { match **self { Place::Ptr(mplace) => Left(MPlaceTy { mplace, layout: self.layout, align: self.align }), - Place::Local { frame, local } => Right((frame, local)), + Place::Local { frame, local, offset } => Right((frame, local, offset)), } } @@ -302,12 +314,76 @@ impl<'tcx, Prov: Provenance> PlaceTy<'tcx, Prov> { } } +impl<'mir, 'tcx: 'mir, Prov: Provenance + 'static> Projectable<'mir, 'tcx, Prov> + for PlaceTy<'tcx, Prov> +{ + #[inline(always)] + fn layout(&self) -> TyAndLayout<'tcx> { + self.layout + } + + fn meta<M: Machine<'mir, 'tcx, Provenance = Prov>>( + &self, + ecx: &InterpCx<'mir, 'tcx, M>, + ) -> InterpResult<'tcx, MemPlaceMeta<M::Provenance>> { + ecx.place_meta(self) + } + + fn offset_with_meta( + &self, + offset: Size, + meta: MemPlaceMeta<Prov>, + layout: TyAndLayout<'tcx>, + cx: &impl HasDataLayout, + ) -> InterpResult<'tcx, Self> { + Ok(match self.as_mplace_or_local() { + Left(mplace) => mplace.offset_with_meta(offset, meta, layout, cx)?.into(), + Right((frame, local, old_offset)) => { + assert_matches!(meta, MemPlaceMeta::None); // we couldn't store it anyway... + let new_offset = cx + .data_layout() + .offset(old_offset.unwrap_or(Size::ZERO).bytes(), offset.bytes())?; + PlaceTy { + place: Place::Local { + frame, + local, + offset: Some(Size::from_bytes(new_offset)), + }, + align: self.align.restrict_for_offset(offset), + layout, + } + } + }) + } + + fn to_op<M: Machine<'mir, 'tcx, Provenance = Prov>>( + &self, + ecx: &InterpCx<'mir, 'tcx, M>, + ) -> InterpResult<'tcx, OpTy<'tcx, M::Provenance>> { + ecx.place_to_op(self) + } +} + // FIXME: Working around https://github.com/rust-lang/rust/issues/54385 impl<'mir, 'tcx: 'mir, Prov, M> InterpCx<'mir, 'tcx, M> where Prov: Provenance + 'static, M: Machine<'mir, 'tcx, Provenance = Prov>, { + /// Get the metadata of the given place. + pub(super) fn place_meta( + &self, + place: &PlaceTy<'tcx, M::Provenance>, + ) -> InterpResult<'tcx, MemPlaceMeta<M::Provenance>> { + if place.layout.is_unsized() { + // For `Place::Local`, the metadata is stored with the local, not the place. So we have + // to look that up first. + self.place_to_op(place)?.meta() + } else { + Ok(MemPlaceMeta::None) + } + } + /// Take a value, which represents a (thin or wide) reference, and make it a place. /// Alignment is just based on the type. This is the inverse of `MemPlace::to_ref()`. /// @@ -327,11 +403,9 @@ where Immediate::Uninit => throw_ub!(InvalidUninitBytes(None)), }; - let mplace = MemPlace { ptr: ptr.to_pointer(self)?, meta }; // `ref_to_mplace` is called on raw pointers even if they don't actually get dereferenced; // we hence can't call `size_and_align_of` since that asserts more validity than we want. - let align = layout.align.abi; - Ok(MPlaceTy { mplace, layout, align }) + Ok(MPlaceTy::from_aligned_ptr_with_meta(ptr.to_pointer(self)?, layout, meta)) } /// Take an operand, representing a pointer, and dereference it to a place. @@ -422,7 +496,7 @@ where local: mir::Local, ) -> InterpResult<'tcx, PlaceTy<'tcx, M::Provenance>> { let layout = self.layout_of_local(&self.stack()[frame], local, None)?; - let place = Place::Local { frame, local }; + let place = Place::Local { frame, local, offset: None }; Ok(PlaceTy { place, layout, align: layout.align.abi }) } @@ -430,13 +504,13 @@ where /// place; for reading, a more efficient alternative is `eval_place_to_op`. #[instrument(skip(self), level = "debug")] pub fn eval_place( - &mut self, + &self, mir_place: mir::Place<'tcx>, ) -> InterpResult<'tcx, PlaceTy<'tcx, M::Provenance>> { let mut place = self.local_to_place(self.frame_idx(), mir_place.local)?; // Using `try_fold` turned out to be bad for performance, hence the loop. for elem in mir_place.projection.iter() { - place = self.place_projection(&place, elem)? + place = self.project(&place, elem)? } trace!("{:?}", self.dump_place(place.place)); @@ -503,22 +577,54 @@ where src: Immediate<M::Provenance>, dest: &PlaceTy<'tcx, M::Provenance>, ) -> InterpResult<'tcx> { - assert!(dest.layout.is_sized(), "Cannot write unsized data"); + assert!(dest.layout.is_sized(), "Cannot write unsized immediate data"); trace!("write_immediate: {:?} <- {:?}: {}", *dest, src, dest.layout.ty); // See if we can avoid an allocation. This is the counterpart to `read_immediate_raw`, // but not factored as a separate function. let mplace = match dest.place { - Place::Local { frame, local } => { - match M::access_local_mut(self, frame, local)? { - Operand::Immediate(local) => { - // Local can be updated in-place. - *local = src; - return Ok(()); - } - Operand::Indirect(mplace) => { - // The local is in memory, go on below. - *mplace + Place::Local { frame, local, offset } => { + if offset.is_some() { + // This has been projected to a part of this local. We could have complicated + // logic to still keep this local as an `Operand`... but it's much easier to + // just fall back to the indirect path. + *self.force_allocation(dest)? + } else { + match M::access_local_mut(self, frame, local)? { + Operand::Immediate(local_val) => { + // Local can be updated in-place. + *local_val = src; + // Double-check that the value we are storing and the local fit to each other. + // (*After* doing the update for borrow checker reasons.) + if cfg!(debug_assertions) { + let local_layout = + self.layout_of_local(&self.stack()[frame], local, None)?; + match (src, local_layout.abi) { + (Immediate::Scalar(scalar), Abi::Scalar(s)) => { + assert_eq!(scalar.size(), s.size(self)) + } + ( + Immediate::ScalarPair(a_val, b_val), + Abi::ScalarPair(a, b), + ) => { + assert_eq!(a_val.size(), a.size(self)); + assert_eq!(b_val.size(), b.size(self)); + } + (Immediate::Uninit, _) => {} + (src, abi) => { + bug!( + "value {src:?} cannot be written into local with type {} (ABI {abi:?})", + local_layout.ty + ) + } + }; + } + return Ok(()); + } + Operand::Indirect(mplace) => { + // The local is in memory, go on below. + *mplace + } } } } @@ -593,15 +699,23 @@ where pub fn write_uninit(&mut self, dest: &PlaceTy<'tcx, M::Provenance>) -> InterpResult<'tcx> { let mplace = match dest.as_mplace_or_local() { Left(mplace) => mplace, - Right((frame, local)) => { - match M::access_local_mut(self, frame, local)? { - Operand::Immediate(local) => { - *local = Immediate::Uninit; - return Ok(()); - } - Operand::Indirect(mplace) => { - // The local is in memory, go on below. - MPlaceTy { mplace: *mplace, layout: dest.layout, align: dest.align } + Right((frame, local, offset)) => { + if offset.is_some() { + // This has been projected to a part of this local. We could have complicated + // logic to still keep this local as an `Operand`... but it's much easier to + // just fall back to the indirect path. + // FIXME: share the logic with `write_immediate_no_validate`. + self.force_allocation(dest)? + } else { + match M::access_local_mut(self, frame, local)? { + Operand::Immediate(local) => { + *local = Immediate::Uninit; + return Ok(()); + } + Operand::Indirect(mplace) => { + // The local is in memory, go on below. + MPlaceTy { mplace: *mplace, layout: dest.layout, align: dest.align } + } } } } @@ -728,8 +842,8 @@ where place: &PlaceTy<'tcx, M::Provenance>, ) -> InterpResult<'tcx, MPlaceTy<'tcx, M::Provenance>> { let mplace = match place.place { - Place::Local { frame, local } => { - match M::access_local_mut(self, frame, local)? { + Place::Local { frame, local, offset } => { + let whole_local = match M::access_local_mut(self, frame, local)? { &mut Operand::Immediate(local_val) => { // We need to make an allocation. @@ -742,10 +856,11 @@ where throw_unsup_format!("unsized locals are not supported"); } let mplace = *self.allocate(local_layout, MemoryKind::Stack)?; + // Preserve old value. (As an optimization, we can skip this if it was uninit.) if !matches!(local_val, Immediate::Uninit) { - // Preserve old value. (As an optimization, we can skip this if it was uninit.) - // We don't have to validate as we can assume the local - // was already valid for its type. + // We don't have to validate as we can assume the local was already + // valid for its type. We must not use any part of `place` here, that + // could be a projection to a part of the local! self.write_immediate_to_mplace_no_validate( local_val, local_layout, @@ -753,18 +868,25 @@ where mplace, )?; } - // Now we can call `access_mut` again, asserting it goes well, - // and actually overwrite things. + // Now we can call `access_mut` again, asserting it goes well, and actually + // overwrite things. This points to the entire allocation, not just the part + // the place refers to, i.e. we do this before we apply `offset`. *M::access_local_mut(self, frame, local).unwrap() = Operand::Indirect(mplace); mplace } &mut Operand::Indirect(mplace) => mplace, // this already was an indirect local + }; + if let Some(offset) = offset { + whole_local.offset_with_meta_(offset, MemPlaceMeta::None, self)? + } else { + // Preserve wide place metadata, do not call `offset`. + whole_local } } Place::Ptr(mplace) => mplace, }; - // Return with the original layout, so that the caller can go on + // Return with the original layout and align, so that the caller can go on Ok(MPlaceTy { mplace, layout: place.layout, align: place.align }) } @@ -809,7 +931,7 @@ where self.write_uninit(&dest)?; let (variant_index, variant_dest, active_field_index) = match *kind { mir::AggregateKind::Adt(_, variant_index, _, _, active_field_index) => { - let variant_dest = self.place_downcast(&dest, variant_index)?; + let variant_dest = self.project_downcast(dest, variant_index)?; (variant_index, variant_dest, active_field_index) } _ => (FIRST_VARIANT, dest.clone(), None), @@ -819,7 +941,7 @@ where } for (field_index, operand) in operands.iter_enumerated() { let field_index = active_field_index.unwrap_or(field_index); - let field_dest = self.place_field(&variant_dest, field_index.as_usize())?; + let field_dest = self.project_field(&variant_dest, field_index.as_usize())?; let op = self.eval_operand(operand, Some(field_dest.layout))?; self.copy_op(&op, &field_dest, /*allow_transmute*/ false)?; } @@ -859,22 +981,24 @@ where Ok((mplace, vtable)) } - /// Turn an operand with a `dyn* Trait` type into an operand with the actual dynamic type. - /// Aso returns the vtable. - pub(super) fn unpack_dyn_star( + /// Turn a `dyn* Trait` type into an value with the actual dynamic type. + /// Also returns the vtable. + pub(super) fn unpack_dyn_star<P: Projectable<'mir, 'tcx, M::Provenance>>( &self, - op: &OpTy<'tcx, M::Provenance>, - ) -> InterpResult<'tcx, (OpTy<'tcx, M::Provenance>, Pointer<Option<M::Provenance>>)> { + val: &P, + ) -> InterpResult<'tcx, (P, Pointer<Option<M::Provenance>>)> { assert!( - matches!(op.layout.ty.kind(), ty::Dynamic(_, _, ty::DynStar)), + matches!(val.layout().ty.kind(), ty::Dynamic(_, _, ty::DynStar)), "`unpack_dyn_star` only makes sense on `dyn*` types" ); - let data = self.operand_field(&op, 0)?; - let vtable = self.operand_field(&op, 1)?; - let vtable = self.read_pointer(&vtable)?; + let data = self.project_field(val, 0)?; + let vtable = self.project_field(val, 1)?; + let vtable = self.read_pointer(&vtable.to_op(self)?)?; let (ty, _) = self.get_ptr_vtable(vtable)?; let layout = self.layout_of(ty)?; - let data = data.transmute(layout); + // `data` is already the right thing but has the wrong type. So we transmute it, by + // projecting with offset 0. + let data = data.transmute(layout, self)?; Ok((data, vtable)) } } |