| //! Computations on places -- field projections, going from mir::Place, and writing |
| //! 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::ty; |
| use rustc_middle::ty::layout::{LayoutOf, TyAndLayout}; |
| use rustc_middle::ty::Ty; |
| use rustc_target::abi::{Abi, Align, FieldIdx, HasDataLayout, Size, FIRST_VARIANT}; |
| |
| use super::{ |
| alloc_range, mir_assign_valid_types, AllocId, AllocRef, AllocRefMut, CheckAlignMsg, ImmTy, |
| Immediate, InterpCx, InterpResult, Machine, MemoryKind, Misalignment, OffsetMode, OpTy, |
| Operand, Pointer, PointerArithmetic, Projectable, Provenance, Readable, Scalar, |
| }; |
| |
| #[derive(Copy, Clone, Hash, PartialEq, Eq, Debug)] |
| /// Information required for the sound usage of a `MemPlace`. |
| pub enum MemPlaceMeta<Prov: Provenance = AllocId> { |
| /// The unsized payload (e.g. length for slices or vtable pointer for trait objects). |
| Meta(Scalar<Prov>), |
| /// `Sized` types or unsized `extern type` |
| None, |
| } |
| |
| impl<Prov: Provenance> MemPlaceMeta<Prov> { |
| #[cfg_attr(debug_assertions, track_caller)] // only in debug builds due to perf (see #98980) |
| pub fn unwrap_meta(self) -> Scalar<Prov> { |
| match self { |
| Self::Meta(s) => s, |
| Self::None => { |
| bug!("expected wide pointer extra data (e.g. slice length or trait object vtable)") |
| } |
| } |
| } |
| |
| #[inline(always)] |
| pub fn has_meta(self) -> bool { |
| match self { |
| Self::Meta(_) => true, |
| Self::None => false, |
| } |
| } |
| } |
| |
| #[derive(Copy, Clone, Hash, PartialEq, Eq, Debug)] |
| pub(super) struct MemPlace<Prov: Provenance = AllocId> { |
| /// The pointer can be a pure integer, with the `None` provenance. |
| pub ptr: Pointer<Option<Prov>>, |
| /// Metadata for unsized places. Interpretation is up to the type. |
| /// Must not be present for sized types, but can be missing for unsized types |
| /// (e.g., `extern type`). |
| pub meta: MemPlaceMeta<Prov>, |
| /// Stores whether this place was created based on a sufficiently aligned pointer. |
| misaligned: Option<Misalignment>, |
| } |
| |
| impl<Prov: Provenance> MemPlace<Prov> { |
| /// 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 } |
| } |
| |
| /// Turn a mplace into a (thin or wide) pointer, as a reference, pointing to the same space. |
| #[inline] |
| pub fn to_ref(self, cx: &impl HasDataLayout) -> Immediate<Prov> { |
| Immediate::new_pointer_with_meta(self.ptr, self.meta, cx) |
| } |
| |
| #[inline] |
| // Not called `offset_with_meta` to avoid confusion with the trait method. |
| fn offset_with_meta_<'mir, 'tcx, M: Machine<'mir, 'tcx, Provenance = Prov>>( |
| self, |
| offset: Size, |
| mode: OffsetMode, |
| meta: MemPlaceMeta<Prov>, |
| ecx: &InterpCx<'mir, 'tcx, M>, |
| ) -> InterpResult<'tcx, Self> { |
| debug_assert!( |
| !meta.has_meta() || self.meta.has_meta(), |
| "cannot use `offset_with_meta` to add metadata to a place" |
| ); |
| if offset > ecx.data_layout().max_size_of_val() { |
| throw_ub!(PointerArithOverflow); |
| } |
| let ptr = match mode { |
| OffsetMode::Inbounds => { |
| ecx.ptr_offset_inbounds(self.ptr, offset.bytes().try_into().unwrap())? |
| } |
| OffsetMode::Wrapping => self.ptr.wrapping_offset(offset, ecx), |
| }; |
| Ok(MemPlace { ptr, meta, misaligned: self.misaligned }) |
| } |
| } |
| |
| /// A MemPlace with its layout. Constructing it is only possible in this module. |
| #[derive(Clone, Hash, Eq, PartialEq)] |
| pub struct MPlaceTy<'tcx, Prov: Provenance = AllocId> { |
| mplace: MemPlace<Prov>, |
| pub layout: TyAndLayout<'tcx>, |
| } |
| |
| impl<Prov: Provenance> std::fmt::Debug for MPlaceTy<'_, Prov> { |
| fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { |
| // Printing `layout` results in too much noise; just print a nice version of the type. |
| f.debug_struct("MPlaceTy") |
| .field("mplace", &self.mplace) |
| .field("ty", &format_args!("{}", self.layout.ty)) |
| .finish() |
| } |
| } |
| |
| 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 |
| /// don't need to worry about memory leaks. |
| #[inline] |
| pub fn fake_alloc_zst(layout: TyAndLayout<'tcx>) -> Self { |
| assert!(layout.is_zst()); |
| let align = layout.align.abi; |
| let ptr = Pointer::from_addr_invalid(align.bytes()); // no provenance, absolute address |
| MPlaceTy { mplace: MemPlace { ptr, meta: MemPlaceMeta::None, misaligned: None }, layout } |
| } |
| |
| /// Adjust the provenance of the main pointer (metadata is unaffected). |
| pub fn map_provenance(self, f: impl FnOnce(Option<Prov>) -> Option<Prov>) -> Self { |
| MPlaceTy { mplace: self.mplace.map_provenance(f), ..self } |
| } |
| |
| #[inline(always)] |
| pub(super) fn mplace(&self) -> &MemPlace<Prov> { |
| &self.mplace |
| } |
| |
| #[inline(always)] |
| pub fn ptr(&self) -> Pointer<Option<Prov>> { |
| self.mplace.ptr |
| } |
| |
| #[inline(always)] |
| pub fn to_ref(&self, cx: &impl HasDataLayout) -> Immediate<Prov> { |
| self.mplace.to_ref(cx) |
| } |
| } |
| |
| impl<'tcx, Prov: Provenance> Projectable<'tcx, Prov> for MPlaceTy<'tcx, Prov> { |
| #[inline(always)] |
| fn layout(&self) -> TyAndLayout<'tcx> { |
| self.layout |
| } |
| |
| #[inline(always)] |
| fn meta(&self) -> MemPlaceMeta<Prov> { |
| self.mplace.meta |
| } |
| |
| fn offset_with_meta<'mir, M: Machine<'mir, 'tcx, Provenance = Prov>>( |
| &self, |
| offset: Size, |
| mode: OffsetMode, |
| meta: MemPlaceMeta<Prov>, |
| layout: TyAndLayout<'tcx>, |
| ecx: &InterpCx<'mir, 'tcx, M>, |
| ) -> InterpResult<'tcx, Self> { |
| Ok(MPlaceTy { mplace: self.mplace.offset_with_meta_(offset, mode, meta, ecx)?, layout }) |
| } |
| |
| fn to_op<'mir, M: Machine<'mir, 'tcx, Provenance = Prov>>( |
| &self, |
| _ecx: &InterpCx<'mir, 'tcx, M>, |
| ) -> InterpResult<'tcx, OpTy<'tcx, M::Provenance>> { |
| Ok(self.clone().into()) |
| } |
| } |
| |
| #[derive(Copy, Clone, Debug)] |
| pub(super) 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. 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`.) |
| /// 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! |
| /// |
| /// This variant shall not be used for unsized types -- those must always live in memory. |
| Local { frame: usize, local: mir::Local, offset: Option<Size> }, |
| } |
| |
| #[derive(Clone)] |
| pub struct PlaceTy<'tcx, Prov: Provenance = AllocId> { |
| place: Place<Prov>, // Keep this private; it helps enforce invariants. |
| pub layout: TyAndLayout<'tcx>, |
| } |
| |
| impl<Prov: Provenance> std::fmt::Debug for PlaceTy<'_, Prov> { |
| fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { |
| // Printing `layout` results in too much noise; just print a nice version of the type. |
| f.debug_struct("PlaceTy") |
| .field("place", &self.place) |
| .field("ty", &format_args!("{}", self.layout.ty)) |
| .finish() |
| } |
| } |
| |
| impl<'tcx, Prov: Provenance> From<MPlaceTy<'tcx, Prov>> for PlaceTy<'tcx, Prov> { |
| #[inline(always)] |
| fn from(mplace: MPlaceTy<'tcx, Prov>) -> Self { |
| PlaceTy { place: Place::Ptr(mplace.mplace), layout: mplace.layout } |
| } |
| } |
| |
| impl<'tcx, Prov: Provenance> PlaceTy<'tcx, Prov> { |
| #[inline(always)] |
| pub(super) fn place(&self) -> &Place<Prov> { |
| &self.place |
| } |
| |
| /// A place is either an mplace or some local. |
| #[inline(always)] |
| pub fn as_mplace_or_local( |
| &self, |
| ) -> Either<MPlaceTy<'tcx, Prov>, (usize, mir::Local, Option<Size>)> { |
| match self.place { |
| Place::Ptr(mplace) => Left(MPlaceTy { mplace, layout: self.layout }), |
| Place::Local { frame, local, offset } => Right((frame, local, offset)), |
| } |
| } |
| |
| #[inline(always)] |
| #[cfg_attr(debug_assertions, track_caller)] // only in debug builds due to perf (see #98980) |
| pub fn assert_mem_place(&self) -> MPlaceTy<'tcx, Prov> { |
| self.as_mplace_or_local().left().unwrap_or_else(|| { |
| bug!( |
| "PlaceTy of type {} was a local when it was expected to be an MPlace", |
| self.layout.ty |
| ) |
| }) |
| } |
| } |
| |
| impl<'tcx, Prov: Provenance> Projectable<'tcx, Prov> for PlaceTy<'tcx, Prov> { |
| #[inline(always)] |
| fn layout(&self) -> TyAndLayout<'tcx> { |
| self.layout |
| } |
| |
| #[inline] |
| fn meta(&self) -> MemPlaceMeta<Prov> { |
| match self.as_mplace_or_local() { |
| Left(mplace) => mplace.meta(), |
| Right(_) => { |
| debug_assert!(self.layout.is_sized(), "unsized locals should live in memory"); |
| MemPlaceMeta::None |
| } |
| } |
| } |
| |
| fn offset_with_meta<'mir, M: Machine<'mir, 'tcx, Provenance = Prov>>( |
| &self, |
| offset: Size, |
| mode: OffsetMode, |
| meta: MemPlaceMeta<Prov>, |
| layout: TyAndLayout<'tcx>, |
| ecx: &InterpCx<'mir, 'tcx, M>, |
| ) -> InterpResult<'tcx, Self> { |
| Ok(match self.as_mplace_or_local() { |
| Left(mplace) => mplace.offset_with_meta(offset, mode, meta, layout, ecx)?.into(), |
| Right((frame, local, old_offset)) => { |
| debug_assert!(layout.is_sized(), "unsized locals should live in memory"); |
| assert_matches!(meta, MemPlaceMeta::None); // we couldn't store it anyway... |
| // `Place::Local` are always in-bounds of their surrounding local, so we can just |
| // check directly if this remains in-bounds. This cannot actually be violated since |
| // projections are type-checked and bounds-checked. |
| assert!(offset + layout.size <= self.layout.size); |
| |
| let new_offset = Size::from_bytes( |
| ecx.data_layout() |
| .offset(old_offset.unwrap_or(Size::ZERO).bytes(), offset.bytes())?, |
| ); |
| |
| PlaceTy { place: Place::Local { frame, local, offset: Some(new_offset) }, layout } |
| } |
| }) |
| } |
| |
| fn to_op<'mir, M: Machine<'mir, 'tcx, Provenance = Prov>>( |
| &self, |
| ecx: &InterpCx<'mir, 'tcx, M>, |
| ) -> InterpResult<'tcx, OpTy<'tcx, M::Provenance>> { |
| ecx.place_to_op(self) |
| } |
| } |
| |
| // These are defined here because they produce a place. |
| impl<'tcx, Prov: Provenance> OpTy<'tcx, Prov> { |
| #[inline(always)] |
| pub fn as_mplace_or_imm(&self) -> Either<MPlaceTy<'tcx, Prov>, ImmTy<'tcx, Prov>> { |
| match self.op() { |
| Operand::Indirect(mplace) => Left(MPlaceTy { mplace: *mplace, layout: self.layout }), |
| Operand::Immediate(imm) => Right(ImmTy::from_immediate(*imm, self.layout)), |
| } |
| } |
| |
| #[inline(always)] |
| #[cfg_attr(debug_assertions, track_caller)] // only in debug builds due to perf (see #98980) |
| pub fn assert_mem_place(&self) -> MPlaceTy<'tcx, Prov> { |
| self.as_mplace_or_imm().left().unwrap_or_else(|| { |
| bug!( |
| "OpTy of type {} was immediate when it was expected to be an MPlace", |
| self.layout.ty |
| ) |
| }) |
| } |
| } |
| |
| /// The `Weiteable` trait describes interpreter values that can be written to. |
| pub trait Writeable<'tcx, Prov: Provenance>: Projectable<'tcx, Prov> { |
| fn as_mplace_or_local( |
| &self, |
| ) -> Either<MPlaceTy<'tcx, Prov>, (usize, mir::Local, Option<Size>, TyAndLayout<'tcx>)>; |
| |
| fn force_mplace<'mir, M: Machine<'mir, 'tcx, Provenance = Prov>>( |
| &self, |
| ecx: &mut InterpCx<'mir, 'tcx, M>, |
| ) -> InterpResult<'tcx, MPlaceTy<'tcx, Prov>>; |
| } |
| |
| impl<'tcx, Prov: Provenance> Writeable<'tcx, Prov> for PlaceTy<'tcx, Prov> { |
| #[inline(always)] |
| fn as_mplace_or_local( |
| &self, |
| ) -> Either<MPlaceTy<'tcx, Prov>, (usize, mir::Local, Option<Size>, TyAndLayout<'tcx>)> { |
| self.as_mplace_or_local() |
| .map_right(|(frame, local, offset)| (frame, local, offset, self.layout)) |
| } |
| |
| #[inline(always)] |
| fn force_mplace<'mir, M: Machine<'mir, 'tcx, Provenance = Prov>>( |
| &self, |
| ecx: &mut InterpCx<'mir, 'tcx, M>, |
| ) -> InterpResult<'tcx, MPlaceTy<'tcx, Prov>> { |
| ecx.force_allocation(self) |
| } |
| } |
| |
| impl<'tcx, Prov: Provenance> Writeable<'tcx, Prov> for MPlaceTy<'tcx, Prov> { |
| #[inline(always)] |
| fn as_mplace_or_local( |
| &self, |
| ) -> Either<MPlaceTy<'tcx, Prov>, (usize, mir::Local, Option<Size>, TyAndLayout<'tcx>)> { |
| Left(self.clone()) |
| } |
| |
| #[inline(always)] |
| fn force_mplace<'mir, M: Machine<'mir, 'tcx, Provenance = Prov>>( |
| &self, |
| _ecx: &mut InterpCx<'mir, 'tcx, M>, |
| ) -> InterpResult<'tcx, MPlaceTy<'tcx, Prov>> { |
| Ok(self.clone()) |
| } |
| } |
| |
| // FIXME: Working around https://github.com/rust-lang/rust/issues/54385 |
| impl<'mir, 'tcx: 'mir, Prov, M> InterpCx<'mir, 'tcx, M> |
| where |
| Prov: Provenance, |
| M: Machine<'mir, 'tcx, Provenance = Prov>, |
| { |
| pub fn ptr_with_meta_to_mplace( |
| &self, |
| ptr: Pointer<Option<M::Provenance>>, |
| meta: MemPlaceMeta<M::Provenance>, |
| layout: TyAndLayout<'tcx>, |
| ) -> MPlaceTy<'tcx, M::Provenance> { |
| let misaligned = self.is_ptr_misaligned(ptr, layout.align.abi); |
| MPlaceTy { mplace: MemPlace { ptr, meta, misaligned }, layout } |
| } |
| |
| pub fn ptr_to_mplace( |
| &self, |
| ptr: Pointer<Option<M::Provenance>>, |
| layout: TyAndLayout<'tcx>, |
| ) -> MPlaceTy<'tcx, M::Provenance> { |
| assert!(layout.is_sized()); |
| self.ptr_with_meta_to_mplace(ptr, MemPlaceMeta::None, layout) |
| } |
| |
| /// 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 `mplace_to_ref()`. |
| /// |
| /// Only call this if you are sure the place is "valid" (aligned and inbounds), or do not |
| /// want to ever use the place for memory access! |
| /// Generally prefer `deref_pointer`. |
| pub fn ref_to_mplace( |
| &self, |
| val: &ImmTy<'tcx, M::Provenance>, |
| ) -> InterpResult<'tcx, MPlaceTy<'tcx, M::Provenance>> { |
| let pointee_type = |
| val.layout.ty.builtin_deref(true).expect("`ref_to_mplace` called on non-ptr type").ty; |
| let layout = self.layout_of(pointee_type)?; |
| let (ptr, meta) = match **val { |
| Immediate::Scalar(ptr) => (ptr, MemPlaceMeta::None), |
| Immediate::ScalarPair(ptr, meta) => (ptr, MemPlaceMeta::Meta(meta)), |
| Immediate::Uninit => throw_ub!(InvalidUninitBytes(None)), |
| }; |
| |
| // `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 ptr = ptr.to_pointer(self)?; |
| Ok(self.ptr_with_meta_to_mplace(ptr, meta, layout)) |
| } |
| |
| /// Turn a mplace into a (thin or wide) mutable raw pointer, pointing to the same space. |
| /// `align` information is lost! |
| /// This is the inverse of `ref_to_mplace`. |
| pub fn mplace_to_ref( |
| &self, |
| mplace: &MPlaceTy<'tcx, M::Provenance>, |
| ) -> InterpResult<'tcx, ImmTy<'tcx, M::Provenance>> { |
| let imm = mplace.mplace.to_ref(self); |
| let layout = self.layout_of(Ty::new_mut_ptr(self.tcx.tcx, mplace.layout.ty))?; |
| Ok(ImmTy::from_immediate(imm, layout)) |
| } |
| |
| /// Take an operand, representing a pointer, and dereference it to a place. |
| /// Corresponds to the `*` operator in Rust. |
| #[instrument(skip(self), level = "debug")] |
| pub fn deref_pointer( |
| &self, |
| src: &impl Readable<'tcx, M::Provenance>, |
| ) -> InterpResult<'tcx, MPlaceTy<'tcx, M::Provenance>> { |
| let val = self.read_immediate(src)?; |
| trace!("deref to {} on {:?}", val.layout.ty, *val); |
| |
| if val.layout.ty.is_box() { |
| bug!("dereferencing {}", val.layout.ty); |
| } |
| |
| let mplace = self.ref_to_mplace(&val)?; |
| Ok(mplace) |
| } |
| |
| #[inline] |
| pub(super) fn get_place_alloc( |
| &self, |
| mplace: &MPlaceTy<'tcx, M::Provenance>, |
| ) -> InterpResult<'tcx, Option<AllocRef<'_, 'tcx, M::Provenance, M::AllocExtra, M::Bytes>>> |
| { |
| let (size, _align) = self |
| .size_and_align_of_mplace(&mplace)? |
| .unwrap_or((mplace.layout.size, mplace.layout.align.abi)); |
| // We check alignment separately, and *after* checking everything else. |
| // If an access is both OOB and misaligned, we want to see the bounds error. |
| let a = self.get_ptr_alloc(mplace.ptr(), size)?; |
| self.check_misalign(mplace.mplace.misaligned, CheckAlignMsg::BasedOn)?; |
| Ok(a) |
| } |
| |
| #[inline] |
| pub(super) fn get_place_alloc_mut( |
| &mut self, |
| mplace: &MPlaceTy<'tcx, M::Provenance>, |
| ) -> InterpResult<'tcx, Option<AllocRefMut<'_, 'tcx, M::Provenance, M::AllocExtra, M::Bytes>>> |
| { |
| let (size, _align) = self |
| .size_and_align_of_mplace(&mplace)? |
| .unwrap_or((mplace.layout.size, mplace.layout.align.abi)); |
| // We check alignment separately, and raise that error *after* checking everything else. |
| // If an access is both OOB and misaligned, we want to see the bounds error. |
| // However we have to call `check_misalign` first to make the borrow checker happy. |
| let misalign_err = self.check_misalign(mplace.mplace.misaligned, CheckAlignMsg::BasedOn); |
| let a = self.get_ptr_alloc_mut(mplace.ptr(), size)?; |
| misalign_err?; |
| Ok(a) |
| } |
| |
| /// Converts a repr(simd) place into a place where `place_index` accesses the SIMD elements. |
| /// Also returns the number of elements. |
| pub fn mplace_to_simd( |
| &self, |
| mplace: &MPlaceTy<'tcx, M::Provenance>, |
| ) -> InterpResult<'tcx, (MPlaceTy<'tcx, M::Provenance>, u64)> { |
| // Basically we just transmute this place into an array following simd_size_and_type. |
| // (Transmuting is okay since this is an in-memory place. We also double-check the size |
| // stays the same.) |
| let (len, e_ty) = mplace.layout.ty.simd_size_and_type(*self.tcx); |
| let array = Ty::new_array(self.tcx.tcx, e_ty, len); |
| let layout = self.layout_of(array)?; |
| let mplace = mplace.transmute(layout, self)?; |
| Ok((mplace, len)) |
| } |
| |
| /// Converts a repr(simd) place into a place where `place_index` accesses the SIMD elements. |
| /// Also returns the number of elements. |
| pub fn place_to_simd( |
| &mut self, |
| place: &PlaceTy<'tcx, M::Provenance>, |
| ) -> InterpResult<'tcx, (MPlaceTy<'tcx, M::Provenance>, u64)> { |
| let mplace = self.force_allocation(place)?; |
| self.mplace_to_simd(&mplace) |
| } |
| |
| pub fn local_to_place( |
| &self, |
| frame: usize, |
| local: mir::Local, |
| ) -> InterpResult<'tcx, PlaceTy<'tcx, M::Provenance>> { |
| // Other parts of the system rely on `Place::Local` never being unsized. |
| // So we eagerly check here if this local has an MPlace, and if yes we use it. |
| let frame_ref = &self.stack()[frame]; |
| let layout = self.layout_of_local(frame_ref, local, None)?; |
| let place = if layout.is_sized() { |
| // We can just always use the `Local` for sized values. |
| Place::Local { frame, local, offset: None } |
| } else { |
| // Unsized `Local` isn't okay (we cannot store the metadata). |
| match frame_ref.locals[local].access()? { |
| Operand::Immediate(_) => { |
| // ConstProp marks *all* locals as `Immediate::Uninit` since it cannot |
| // efficiently check whether they are sized. We have to catch that case here. |
| throw_inval!(ConstPropNonsense); |
| } |
| Operand::Indirect(mplace) => Place::Ptr(*mplace), |
| } |
| }; |
| Ok(PlaceTy { place, layout }) |
| } |
| |
| /// Computes a place. You should only use this if you intend to write into this |
| /// place; for reading, a more efficient alternative is `eval_place_to_op`. |
| #[instrument(skip(self), level = "debug")] |
| pub fn eval_place( |
| &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.project(&place, elem)? |
| } |
| |
| trace!("{:?}", self.dump_place(&place)); |
| // Sanity-check the type we ended up with. |
| if cfg!(debug_assertions) { |
| let normalized_place_ty = self.subst_from_current_frame_and_normalize_erasing_regions( |
| mir_place.ty(&self.frame().body.local_decls, *self.tcx).ty, |
| )?; |
| if !mir_assign_valid_types( |
| *self.tcx, |
| self.param_env, |
| self.layout_of(normalized_place_ty)?, |
| place.layout, |
| ) { |
| span_bug!( |
| self.cur_span(), |
| "eval_place of a MIR place with type {} produced an interpreter place with type {}", |
| normalized_place_ty, |
| place.layout.ty, |
| ) |
| } |
| } |
| Ok(place) |
| } |
| |
| /// Write an immediate to a place |
| #[inline(always)] |
| #[instrument(skip(self), level = "debug")] |
| pub fn write_immediate( |
| &mut self, |
| src: Immediate<M::Provenance>, |
| dest: &impl Writeable<'tcx, M::Provenance>, |
| ) -> InterpResult<'tcx> { |
| self.write_immediate_no_validate(src, dest)?; |
| |
| if M::enforce_validity(self, dest.layout()) { |
| // Data got changed, better make sure it matches the type! |
| self.validate_operand(&dest.to_op(self)?)?; |
| } |
| |
| Ok(()) |
| } |
| |
| /// Write a scalar to a place |
| #[inline(always)] |
| pub fn write_scalar( |
| &mut self, |
| val: impl Into<Scalar<M::Provenance>>, |
| dest: &impl Writeable<'tcx, M::Provenance>, |
| ) -> InterpResult<'tcx> { |
| self.write_immediate(Immediate::Scalar(val.into()), dest) |
| } |
| |
| /// Write a pointer to a place |
| #[inline(always)] |
| pub fn write_pointer( |
| &mut self, |
| ptr: impl Into<Pointer<Option<M::Provenance>>>, |
| dest: &impl Writeable<'tcx, M::Provenance>, |
| ) -> InterpResult<'tcx> { |
| self.write_scalar(Scalar::from_maybe_pointer(ptr.into(), self), dest) |
| } |
| |
| /// Write an immediate to a place. |
| /// If you use this you are responsible for validating that things got copied at the |
| /// right type. |
| fn write_immediate_no_validate( |
| &mut self, |
| src: Immediate<M::Provenance>, |
| dest: &impl Writeable<'tcx, M::Provenance>, |
| ) -> InterpResult<'tcx> { |
| assert!(dest.layout().is_sized(), "Cannot write unsized immediate data"); |
| |
| // 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.as_mplace_or_local() { |
| Right((frame, local, offset, layout)) => { |
| 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. |
| dest.force_mplace(self)? |
| } else { |
| M::before_access_local_mut(self, frame, local)?; |
| match self.stack_mut()[frame].locals[local].access_mut()? { |
| 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. |
| MPlaceTy { mplace: *mplace, layout } |
| } |
| } |
| } |
| } |
| Left(mplace) => mplace, // already referring to memory |
| }; |
| |
| // This is already in memory, write there. |
| self.write_immediate_to_mplace_no_validate(src, mplace.layout, mplace.mplace) |
| } |
| |
| /// Write an immediate to memory. |
| /// If you use this you are responsible for validating that things got copied at the |
| /// right layout. |
| fn write_immediate_to_mplace_no_validate( |
| &mut self, |
| value: Immediate<M::Provenance>, |
| layout: TyAndLayout<'tcx>, |
| dest: MemPlace<M::Provenance>, |
| ) -> InterpResult<'tcx> { |
| // Note that it is really important that the type here is the right one, and matches the |
| // type things are read at. In case `value` is a `ScalarPair`, we don't do any magic here |
| // to handle padding properly, which is only correct if we never look at this data with the |
| // wrong type. |
| |
| let tcx = *self.tcx; |
| let Some(mut alloc) = self.get_place_alloc_mut(&MPlaceTy { mplace: dest, layout })? else { |
| // zero-sized access |
| return Ok(()); |
| }; |
| |
| match value { |
| Immediate::Scalar(scalar) => { |
| let Abi::Scalar(s) = layout.abi else { |
| span_bug!( |
| self.cur_span(), |
| "write_immediate_to_mplace: invalid Scalar layout: {layout:#?}", |
| ) |
| }; |
| let size = s.size(&tcx); |
| assert_eq!(size, layout.size, "abi::Scalar size does not match layout size"); |
| alloc.write_scalar(alloc_range(Size::ZERO, size), scalar) |
| } |
| Immediate::ScalarPair(a_val, b_val) => { |
| let Abi::ScalarPair(a, b) = layout.abi else { |
| span_bug!( |
| self.cur_span(), |
| "write_immediate_to_mplace: invalid ScalarPair layout: {:#?}", |
| layout |
| ) |
| }; |
| let (a_size, b_size) = (a.size(&tcx), b.size(&tcx)); |
| let b_offset = a_size.align_to(b.align(&tcx).abi); |
| assert!(b_offset.bytes() > 0); // in `operand_field` we use the offset to tell apart the fields |
| |
| // It is tempting to verify `b_offset` against `layout.fields.offset(1)`, |
| // but that does not work: We could be a newtype around a pair, then the |
| // fields do not match the `ScalarPair` components. |
| |
| alloc.write_scalar(alloc_range(Size::ZERO, a_size), a_val)?; |
| alloc.write_scalar(alloc_range(b_offset, b_size), b_val) |
| } |
| Immediate::Uninit => alloc.write_uninit(), |
| } |
| } |
| |
| pub fn write_uninit( |
| &mut self, |
| dest: &impl Writeable<'tcx, M::Provenance>, |
| ) -> InterpResult<'tcx> { |
| let mplace = match dest.as_mplace_or_local() { |
| Left(mplace) => mplace, |
| Right((frame, local, offset, layout)) => { |
| 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`. |
| dest.force_mplace(self)? |
| } else { |
| M::before_access_local_mut(self, frame, local)?; |
| match self.stack_mut()[frame].locals[local].access_mut()? { |
| Operand::Immediate(local) => { |
| *local = Immediate::Uninit; |
| return Ok(()); |
| } |
| Operand::Indirect(mplace) => { |
| // The local is in memory, go on below. |
| MPlaceTy { mplace: *mplace, layout } |
| } |
| } |
| } |
| } |
| }; |
| let Some(mut alloc) = self.get_place_alloc_mut(&mplace)? else { |
| // Zero-sized access |
| return Ok(()); |
| }; |
| alloc.write_uninit()?; |
| Ok(()) |
| } |
| |
| /// Copies the data from an operand to a place. |
| /// `allow_transmute` indicates whether the layouts may disagree. |
| #[inline(always)] |
| #[instrument(skip(self), level = "debug")] |
| pub fn copy_op( |
| &mut self, |
| src: &impl Readable<'tcx, M::Provenance>, |
| dest: &impl Writeable<'tcx, M::Provenance>, |
| allow_transmute: bool, |
| ) -> InterpResult<'tcx> { |
| // Generally for transmutation, data must be valid both at the old and new type. |
| // But if the types are the same, the 2nd validation below suffices. |
| if src.layout().ty != dest.layout().ty && M::enforce_validity(self, src.layout()) { |
| self.validate_operand(&src.to_op(self)?)?; |
| } |
| |
| // Do the actual copy. |
| self.copy_op_no_validate(src, dest, allow_transmute)?; |
| |
| if M::enforce_validity(self, dest.layout()) { |
| // Data got changed, better make sure it matches the type! |
| self.validate_operand(&dest.to_op(self)?)?; |
| } |
| |
| Ok(()) |
| } |
| |
| /// Copies the data from an operand to a place. |
| /// `allow_transmute` indicates whether the layouts may disagree. |
| /// Also, if you use this you are responsible for validating that things get copied at the |
| /// right type. |
| #[instrument(skip(self), level = "debug")] |
| fn copy_op_no_validate( |
| &mut self, |
| src: &impl Readable<'tcx, M::Provenance>, |
| dest: &impl Writeable<'tcx, M::Provenance>, |
| allow_transmute: bool, |
| ) -> InterpResult<'tcx> { |
| // We do NOT compare the types for equality, because well-typed code can |
| // actually "transmute" `&mut T` to `&T` in an assignment without a cast. |
| let layout_compat = |
| mir_assign_valid_types(*self.tcx, self.param_env, src.layout(), dest.layout()); |
| if !allow_transmute && !layout_compat { |
| span_bug!( |
| self.cur_span(), |
| "type mismatch when copying!\nsrc: {},\ndest: {}", |
| src.layout().ty, |
| dest.layout().ty, |
| ); |
| } |
| |
| // Let us see if the layout is simple so we take a shortcut, |
| // avoid force_allocation. |
| let src = match self.read_immediate_raw(src)? { |
| Right(src_val) => { |
| // FIXME(const_prop): Const-prop can possibly evaluate an |
| // unsized copy operation when it thinks that the type is |
| // actually sized, due to a trivially false where-clause |
| // predicate like `where Self: Sized` with `Self = dyn Trait`. |
| // See #102553 for an example of such a predicate. |
| if src.layout().is_unsized() { |
| throw_inval!(ConstPropNonsense); |
| } |
| if dest.layout().is_unsized() { |
| throw_inval!(ConstPropNonsense); |
| } |
| assert_eq!(src.layout().size, dest.layout().size); |
| // Yay, we got a value that we can write directly. |
| return if layout_compat { |
| self.write_immediate_no_validate(*src_val, dest) |
| } else { |
| // This is tricky. The problematic case is `ScalarPair`: the `src_val` was |
| // loaded using the offsets defined by `src.layout`. When we put this back into |
| // the destination, we have to use the same offsets! So (a) we make sure we |
| // write back to memory, and (b) we use `dest` *with the source layout*. |
| let dest_mem = dest.force_mplace(self)?; |
| self.write_immediate_to_mplace_no_validate( |
| *src_val, |
| src.layout(), |
| dest_mem.mplace, |
| ) |
| }; |
| } |
| Left(mplace) => mplace, |
| }; |
| // Slow path, this does not fit into an immediate. Just memcpy. |
| trace!("copy_op: {:?} <- {:?}: {}", *dest, src, dest.layout().ty); |
| |
| let dest = dest.force_mplace(self)?; |
| let Some((dest_size, _)) = self.size_and_align_of_mplace(&dest)? else { |
| span_bug!(self.cur_span(), "copy_op needs (dynamically) sized values") |
| }; |
| if cfg!(debug_assertions) { |
| let src_size = self.size_and_align_of_mplace(&src)?.unwrap().0; |
| assert_eq!(src_size, dest_size, "Cannot copy differently-sized data"); |
| } else { |
| // As a cheap approximation, we compare the fixed parts of the size. |
| assert_eq!(src.layout.size, dest.layout.size); |
| } |
| |
| // Setting `nonoverlapping` here only has an effect when we don't hit the fast-path above, |
| // but that should at least match what LLVM does where `memcpy` is also only used when the |
| // type does not have Scalar/ScalarPair layout. |
| // (Or as the `Assign` docs put it, assignments "not producing primitives" must be |
| // non-overlapping.) |
| // We check alignment separately, and *after* checking everything else. |
| // If an access is both OOB and misaligned, we want to see the bounds error. |
| self.mem_copy(src.ptr(), dest.ptr(), dest_size, /*nonoverlapping*/ true)?; |
| self.check_misalign(src.mplace.misaligned, CheckAlignMsg::BasedOn)?; |
| self.check_misalign(dest.mplace.misaligned, CheckAlignMsg::BasedOn)?; |
| Ok(()) |
| } |
| |
| /// Ensures that a place is in memory, and returns where it is. |
| /// If the place currently refers to a local that doesn't yet have a matching allocation, |
| /// create such an allocation. |
| /// This is essentially `force_to_memplace`. |
| #[instrument(skip(self), level = "debug")] |
| pub fn force_allocation( |
| &mut self, |
| place: &PlaceTy<'tcx, M::Provenance>, |
| ) -> InterpResult<'tcx, MPlaceTy<'tcx, M::Provenance>> { |
| let mplace = match place.place { |
| Place::Local { frame, local, offset } => { |
| M::before_access_local_mut(self, frame, local)?; |
| let whole_local = match self.stack_mut()[frame].locals[local].access_mut()? { |
| &mut Operand::Immediate(local_val) => { |
| // We need to make an allocation. |
| |
| // We need the layout of the local. We can NOT use the layout we got, |
| // that might e.g., be an inner field of a struct with `Scalar` layout, |
| // that has different alignment than the outer field. |
| let local_layout = |
| self.layout_of_local(&self.stack()[frame], local, None)?; |
| assert!(local_layout.is_sized(), "unsized locals cannot be immediate"); |
| 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) { |
| // 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, |
| mplace.mplace, |
| )?; |
| } |
| M::after_local_allocated(self, frame, local, &mplace)?; |
| // 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`. |
| *self.stack_mut()[frame].locals[local].access_mut().unwrap() = |
| Operand::Indirect(mplace.mplace); |
| mplace.mplace |
| } |
| &mut Operand::Indirect(mplace) => mplace, // this already was an indirect local |
| }; |
| if let Some(offset) = offset { |
| // This offset is always inbounds, no need to check it again. |
| whole_local.offset_with_meta_( |
| offset, |
| OffsetMode::Wrapping, |
| MemPlaceMeta::None, |
| self, |
| )? |
| } else { |
| // Preserve wide place metadata, do not call `offset`. |
| whole_local |
| } |
| } |
| Place::Ptr(mplace) => mplace, |
| }; |
| // Return with the original layout and align, so that the caller can go on |
| Ok(MPlaceTy { mplace, layout: place.layout }) |
| } |
| |
| pub fn allocate_dyn( |
| &mut self, |
| layout: TyAndLayout<'tcx>, |
| kind: MemoryKind<M::MemoryKind>, |
| meta: MemPlaceMeta<M::Provenance>, |
| ) -> InterpResult<'tcx, MPlaceTy<'tcx, M::Provenance>> { |
| let Some((size, align)) = self.size_and_align_of(&meta, &layout)? else { |
| span_bug!(self.cur_span(), "cannot allocate space for `extern` type, size is not known") |
| }; |
| let ptr = self.allocate_ptr(size, align, kind)?; |
| Ok(self.ptr_with_meta_to_mplace(ptr.into(), meta, layout)) |
| } |
| |
| pub fn allocate( |
| &mut self, |
| layout: TyAndLayout<'tcx>, |
| kind: MemoryKind<M::MemoryKind>, |
| ) -> InterpResult<'tcx, MPlaceTy<'tcx, M::Provenance>> { |
| assert!(layout.is_sized()); |
| self.allocate_dyn(layout, kind, MemPlaceMeta::None) |
| } |
| |
| /// Returns a wide MPlace of type `str` to a new 1-aligned allocation. |
| pub fn allocate_str( |
| &mut self, |
| str: &str, |
| kind: MemoryKind<M::MemoryKind>, |
| mutbl: Mutability, |
| ) -> InterpResult<'tcx, MPlaceTy<'tcx, M::Provenance>> { |
| let ptr = self.allocate_bytes_ptr(str.as_bytes(), Align::ONE, kind, mutbl)?; |
| let meta = Scalar::from_target_usize(u64::try_from(str.len()).unwrap(), self); |
| let layout = self.layout_of(self.tcx.types.str_).unwrap(); |
| Ok(self.ptr_with_meta_to_mplace(ptr.into(), MemPlaceMeta::Meta(meta), layout)) |
| } |
| |
| /// Writes the aggregate to the destination. |
| #[instrument(skip(self), level = "trace")] |
| pub fn write_aggregate( |
| &mut self, |
| kind: &mir::AggregateKind<'tcx>, |
| operands: &IndexSlice<FieldIdx, mir::Operand<'tcx>>, |
| dest: &PlaceTy<'tcx, M::Provenance>, |
| ) -> InterpResult<'tcx> { |
| 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.project_downcast(dest, variant_index)?; |
| (variant_index, variant_dest, active_field_index) |
| } |
| _ => (FIRST_VARIANT, dest.clone(), None), |
| }; |
| if active_field_index.is_some() { |
| assert_eq!(operands.len(), 1); |
| } |
| for (field_index, operand) in operands.iter_enumerated() { |
| let field_index = active_field_index.unwrap_or(field_index); |
| 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)?; |
| } |
| self.write_discriminant(variant_index, dest) |
| } |
| |
| pub fn raw_const_to_mplace( |
| &self, |
| raw: mir::ConstAlloc<'tcx>, |
| ) -> InterpResult<'tcx, MPlaceTy<'tcx, M::Provenance>> { |
| // This must be an allocation in `tcx` |
| let _ = self.tcx.global_alloc(raw.alloc_id); |
| let ptr = self.global_base_pointer(Pointer::from(raw.alloc_id))?; |
| let layout = self.layout_of(raw.ty)?; |
| Ok(self.ptr_to_mplace(ptr.into(), layout)) |
| } |
| |
| /// Turn a place with a `dyn Trait` type into a place with the actual dynamic type. |
| /// Aso returns the vtable. |
| pub(super) fn unpack_dyn_trait( |
| &self, |
| mplace: &MPlaceTy<'tcx, M::Provenance>, |
| ) -> InterpResult<'tcx, (MPlaceTy<'tcx, M::Provenance>, Pointer<Option<M::Provenance>>)> { |
| assert!( |
| matches!(mplace.layout.ty.kind(), ty::Dynamic(_, _, ty::Dyn)), |
| "`unpack_dyn_trait` only makes sense on `dyn*` types" |
| ); |
| let vtable = mplace.meta().unwrap_meta().to_pointer(self)?; |
| let (ty, _) = self.get_ptr_vtable(vtable)?; |
| let layout = self.layout_of(ty)?; |
| // This is a kind of transmute, from a place with unsized type and metadata to |
| // a place with sized type and no metadata. |
| let mplace = |
| MPlaceTy { mplace: MemPlace { meta: MemPlaceMeta::None, ..mplace.mplace }, layout }; |
| Ok((mplace, vtable)) |
| } |
| |
| /// 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<'tcx, M::Provenance>>( |
| &self, |
| val: &P, |
| ) -> InterpResult<'tcx, (P, Pointer<Option<M::Provenance>>)> { |
| assert!( |
| matches!(val.layout().ty.kind(), ty::Dynamic(_, _, ty::DynStar)), |
| "`unpack_dyn_star` only makes sense on `dyn*` types" |
| ); |
| 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)?; |
| // `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)) |
| } |
| } |
| |
| // Some nodes are used a lot. Make sure they don't unintentionally get bigger. |
| #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))] |
| mod size_asserts { |
| use super::*; |
| use rustc_data_structures::static_assert_size; |
| // tidy-alphabetical-start |
| static_assert_size!(MemPlace, 48); |
| static_assert_size!(MemPlaceMeta, 24); |
| static_assert_size!(MPlaceTy<'_>, 64); |
| static_assert_size!(Place, 48); |
| static_assert_size!(PlaceTy<'_>, 64); |
| // tidy-alphabetical-end |
| } |
