| //! 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 rustc_ast::Mutability; |
| use rustc_middle::mir; |
| use rustc_middle::ty; |
| use rustc_middle::ty::layout::{LayoutOf, PrimitiveExt, TyAndLayout}; |
| use rustc_target::abi::{self, Abi, Align, HasDataLayout, Size, TagEncoding, VariantIdx}; |
| |
| use super::{ |
| alloc_range, mir_assign_valid_types, AllocId, AllocRef, AllocRefMut, CheckInAllocMsg, |
| ConstAlloc, ImmTy, Immediate, InterpCx, InterpResult, Machine, MemoryKind, OpTy, Operand, |
| Pointer, Provenance, 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> { |
| 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)") |
| } |
| } |
| } |
| |
| pub fn has_meta(self) -> bool { |
| match self { |
| Self::Meta(_) => true, |
| Self::None => false, |
| } |
| } |
| } |
| |
| #[derive(Copy, Clone, Hash, PartialEq, Eq, Debug)] |
| pub 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>, |
| } |
| |
| /// A MemPlace with its layout. Constructing it is only possible in this module. |
| #[derive(Copy, Clone, Hash, Eq, PartialEq, Debug)] |
| pub struct MPlaceTy<'tcx, Prov: Provenance = AllocId> { |
| mplace: MemPlace<Prov>, |
| pub layout: TyAndLayout<'tcx>, |
| /// rustc does not have a proper way to represent the type of a field of a `repr(packed)` struct: |
| /// it needs to have a different alignment than the field type would usually have. |
| /// So we represent this here with a separate field that "overwrites" `layout.align`. |
| /// This means `layout.align` should never be used for a `MPlaceTy`! |
| pub align: Align, |
| } |
| |
| #[derive(Copy, Clone, Debug)] |
| 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. |
| /// (Without that optimization, we'd just always be a `MemPlace`.) |
| Local { frame: usize, local: mir::Local }, |
| } |
| |
| #[derive(Clone, Debug)] |
| pub struct PlaceTy<'tcx, Prov: Provenance = AllocId> { |
| place: Place<Prov>, // Keep this private; it helps enforce invariants. |
| pub layout: TyAndLayout<'tcx>, |
| /// rustc does not have a proper way to represent the type of a field of a `repr(packed)` struct: |
| /// it needs to have a different alignment than the field type would usually have. |
| /// So we represent this here with a separate field that "overwrites" `layout.align`. |
| /// This means `layout.align` should never be used for a `PlaceTy`! |
| pub align: Align, |
| } |
| |
| impl<'tcx, Prov: Provenance> std::ops::Deref for PlaceTy<'tcx, Prov> { |
| type Target = Place<Prov>; |
| #[inline(always)] |
| fn deref(&self) -> &Place<Prov> { |
| &self.place |
| } |
| } |
| |
| impl<'tcx, Prov: Provenance> std::ops::Deref for MPlaceTy<'tcx, Prov> { |
| type Target = MemPlace<Prov>; |
| #[inline(always)] |
| fn deref(&self) -> &MemPlace<Prov> { |
| &self.mplace |
| } |
| } |
| |
| 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), layout: mplace.layout, align: mplace.align } |
| } |
| } |
| |
| 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), layout: mplace.layout, align: mplace.align } |
| } |
| } |
| |
| impl<'tcx, Prov: Provenance> From<&'_ mut MPlaceTy<'tcx, Prov>> for PlaceTy<'tcx, Prov> { |
| #[inline(always)] |
| fn from(mplace: &mut MPlaceTy<'tcx, Prov>) -> Self { |
| PlaceTy { place: Place::Ptr(**mplace), layout: mplace.layout, align: mplace.align } |
| } |
| } |
| |
| impl<Prov: Provenance> MemPlace<Prov> { |
| #[inline(always)] |
| pub fn from_ptr(ptr: Pointer<Option<Prov>>) -> Self { |
| MemPlace { ptr, meta: MemPlaceMeta::None } |
| } |
| |
| /// 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. |
| /// This is the inverse of `ref_to_mplace`. |
| #[inline(always)] |
| pub fn to_ref(self, cx: &impl HasDataLayout) -> Immediate<Prov> { |
| match self.meta { |
| MemPlaceMeta::None => Immediate::from(Scalar::from_maybe_pointer(self.ptr, cx)), |
| MemPlaceMeta::Meta(meta) => { |
| Immediate::ScalarPair(Scalar::from_maybe_pointer(self.ptr, cx).into(), meta.into()) |
| } |
| } |
| } |
| |
| #[inline] |
| pub fn offset_with_meta<'tcx>( |
| self, |
| offset: Size, |
| meta: MemPlaceMeta<Prov>, |
| cx: &impl HasDataLayout, |
| ) -> InterpResult<'tcx, Self> { |
| Ok(MemPlace { ptr: self.ptr.offset(offset, cx)?, meta }) |
| } |
| } |
| |
| 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 |
| /// 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(align.bytes()); // no provenance, absolute address |
| MPlaceTy { mplace: MemPlace { ptr, meta: MemPlaceMeta::None }, layout, align } |
| } |
| |
| #[inline] |
| pub 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, |
| }) |
| } |
| |
| pub fn offset( |
| &self, |
| offset: Size, |
| layout: TyAndLayout<'tcx>, |
| cx: &impl HasDataLayout, |
| ) -> InterpResult<'tcx, Self> { |
| assert!(!layout.is_unsized()); |
| 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 } |
| } |
| |
| #[inline] |
| pub fn from_aligned_ptr_with_meta( |
| ptr: Pointer<Option<Prov>>, |
| layout: TyAndLayout<'tcx>, |
| meta: MemPlaceMeta<Prov>, |
| ) -> Self { |
| let mut mplace = MemPlace::from_ptr(ptr); |
| mplace.meta = meta; |
| |
| MPlaceTy { mplace, layout, align: layout.align.abi } |
| } |
| |
| #[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_machine_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), |
| } |
| } |
| } |
| |
| #[inline] |
| pub(super) fn vtable(&self) -> Scalar<Prov> { |
| match self.layout.ty.kind() { |
| ty::Dynamic(..) => self.mplace.meta.unwrap_meta(), |
| _ => bug!("vtable not supported on type {:?}", self.layout.ty), |
| } |
| } |
| } |
| |
| // These are defined here because they produce a place. |
| impl<'tcx, Prov: Provenance> OpTy<'tcx, Prov> { |
| #[inline(always)] |
| pub fn try_as_mplace(&self) -> Result<MPlaceTy<'tcx, Prov>, ImmTy<'tcx, Prov>> { |
| match **self { |
| Operand::Indirect(mplace) => { |
| Ok(MPlaceTy { mplace, layout: self.layout, align: self.align.unwrap() }) |
| } |
| Operand::Immediate(imm) => Err(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.try_as_mplace().unwrap() |
| } |
| } |
| |
| impl<'tcx, Prov: Provenance> PlaceTy<'tcx, Prov> { |
| /// A place is either an mplace or some local. |
| #[inline] |
| pub fn try_as_mplace(&self) -> Result<MPlaceTy<'tcx, Prov>, (usize, mir::Local)> { |
| match **self { |
| Place::Ptr(mplace) => Ok(MPlaceTy { mplace, layout: self.layout, align: self.align }), |
| Place::Local { frame, local } => Err((frame, local)), |
| } |
| } |
| |
| #[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.try_as_mplace().unwrap() |
| } |
| } |
| |
| // 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>, |
| { |
| /// 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()`. |
| /// |
| /// 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_operand`. |
| 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)), |
| }; |
| |
| let mplace = MemPlace { ptr: ptr.to_pointer(self)?, meta }; |
| // When deref'ing a pointer, the *static* alignment given by the type is what matters. |
| let align = layout.align.abi; |
| Ok(MPlaceTy { mplace, layout, align }) |
| } |
| |
| /// Take an operand, representing a pointer, and dereference it to a place -- that |
| /// will always be a MemPlace. Lives in `place.rs` because it creates a place. |
| #[instrument(skip(self), level = "debug")] |
| pub fn deref_operand( |
| &self, |
| src: &OpTy<'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)?; |
| self.check_mplace_access(mplace, CheckInAllocMsg::DerefTest)?; |
| Ok(mplace) |
| } |
| |
| #[inline] |
| pub(super) fn get_place_alloc( |
| &self, |
| place: &MPlaceTy<'tcx, M::Provenance>, |
| ) -> InterpResult<'tcx, Option<AllocRef<'_, 'tcx, M::Provenance, M::AllocExtra>>> { |
| assert!(!place.layout.is_unsized()); |
| assert!(!place.meta.has_meta()); |
| let size = place.layout.size; |
| self.get_ptr_alloc(place.ptr, size, place.align) |
| } |
| |
| #[inline] |
| pub(super) fn get_place_alloc_mut( |
| &mut self, |
| place: &MPlaceTy<'tcx, M::Provenance>, |
| ) -> InterpResult<'tcx, Option<AllocRefMut<'_, 'tcx, M::Provenance, M::AllocExtra>>> { |
| assert!(!place.layout.is_unsized()); |
| assert!(!place.meta.has_meta()); |
| let size = place.layout.size; |
| self.get_ptr_alloc_mut(place.ptr, size, place.align) |
| } |
| |
| /// Check if this mplace is dereferenceable and sufficiently aligned. |
| fn check_mplace_access( |
| &self, |
| mplace: MPlaceTy<'tcx, M::Provenance>, |
| msg: CheckInAllocMsg, |
| ) -> InterpResult<'tcx> { |
| let (size, align) = self |
| .size_and_align_of_mplace(&mplace)? |
| .unwrap_or((mplace.layout.size, mplace.layout.align.abi)); |
| assert!(mplace.align <= align, "dynamic alignment less strict than static one?"); |
| let align = M::enforce_alignment(self).then_some(align); |
| self.check_ptr_access_align(mplace.ptr, size, align.unwrap_or(Align::ONE), msg)?; |
| Ok(()) |
| } |
| |
| /// 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 = self.tcx.mk_array(e_ty, len); |
| let layout = self.layout_of(array)?; |
| assert_eq!(layout.size, mplace.layout.size); |
| Ok((MPlaceTy { layout, ..*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>> { |
| let layout = self.layout_of_local(&self.stack()[frame], local, None)?; |
| let place = Place::Local { frame, local }; |
| Ok(PlaceTy { place, layout, align: layout.align.abi }) |
| } |
| |
| /// 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( |
| &mut 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)? |
| } |
| |
| trace!("{:?}", self.dump_place(place.place)); |
| // Sanity-check the type we ended up with. |
| debug_assert!( |
| mir_assign_valid_types( |
| *self.tcx, |
| self.param_env, |
| self.layout_of(self.subst_from_current_frame_and_normalize_erasing_regions( |
| mir_place.ty(&self.frame().body.local_decls, *self.tcx).ty |
| )?)?, |
| place.layout, |
| ), |
| "eval_place of a MIR place with type {:?} produced an interpreter place with type {:?}", |
| mir_place.ty(&self.frame().body.local_decls, *self.tcx).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: &PlaceTy<'tcx, M::Provenance>, |
| ) -> InterpResult<'tcx> { |
| self.write_immediate_no_validate(src, dest)?; |
| |
| if M::enforce_validity(self) { |
| // Data got changed, better make sure it matches the type! |
| self.validate_operand(&self.place_to_op(dest)?)?; |
| } |
| |
| Ok(()) |
| } |
| |
| /// Write a scalar to a place |
| #[inline(always)] |
| pub fn write_scalar( |
| &mut self, |
| val: impl Into<Scalar<M::Provenance>>, |
| dest: &PlaceTy<'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: &PlaceTy<'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: &PlaceTy<'tcx, M::Provenance>, |
| ) -> InterpResult<'tcx> { |
| assert!(!dest.layout.is_unsized(), "Cannot write unsized 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::Ptr(mplace) => mplace, // already referring to memory |
| }; |
| |
| // This is already in memory, write there. |
| self.write_immediate_to_mplace_no_validate(src, dest.layout, dest.align, 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>, |
| align: Align, |
| 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, align })? 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) => { |
| // We checked `ptr_align` above, so all fields will have the alignment they need. |
| // We would anyway check against `ptr_align.restrict_for_offset(b_offset)`, |
| // which `ptr.offset(b_offset)` cannot possibly fail to satisfy. |
| 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: &PlaceTy<'tcx, M::Provenance>) -> InterpResult<'tcx> { |
| let mplace = match dest.try_as_mplace() { |
| Ok(mplace) => mplace, |
| Err((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 } |
| } |
| } |
| } |
| }; |
| 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: &OpTy<'tcx, M::Provenance>, |
| dest: &PlaceTy<'tcx, M::Provenance>, |
| allow_transmute: bool, |
| ) -> InterpResult<'tcx> { |
| self.copy_op_no_validate(src, dest, allow_transmute)?; |
| |
| if M::enforce_validity(self) { |
| // Data got changed, better make sure it matches the type! |
| self.validate_operand(&self.place_to_op(dest)?)?; |
| } |
| |
| 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: &OpTy<'tcx, M::Provenance>, |
| dest: &PlaceTy<'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)? { |
| Ok(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!(SizeOfUnsizedType(src.layout.ty)); |
| } |
| if dest.layout.is_unsized() { |
| throw_inval!(SizeOfUnsizedType(dest.layout.ty)); |
| } |
| 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 = self.force_allocation(dest)?; |
| self.write_immediate_to_mplace_no_validate( |
| *src_val, |
| src.layout, |
| dest_mem.align, |
| *dest_mem, |
| ) |
| }; |
| } |
| Err(mplace) => mplace, |
| }; |
| // Slow path, this does not fit into an immediate. Just memcpy. |
| trace!("copy_op: {:?} <- {:?}: {}", *dest, src, dest.layout.ty); |
| |
| let dest = self.force_allocation(&dest)?; |
| 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); |
| } |
| |
| self.mem_copy( |
| src.ptr, src.align, dest.ptr, dest.align, dest_size, /*nonoverlapping*/ false, |
| ) |
| } |
| |
| /// 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 } => { |
| match M::access_local_mut(self, frame, local)? { |
| &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)?; |
| if local_layout.is_unsized() { |
| throw_unsup_format!("unsized locals are not supported"); |
| } |
| let mplace = *self.allocate(local_layout, MemoryKind::Stack)?; |
| 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. |
| self.write_immediate_to_mplace_no_validate( |
| local_val, |
| local_layout, |
| local_layout.align.abi, |
| mplace, |
| )?; |
| } |
| // Now we can call `access_mut` again, asserting it goes well, |
| // and actually overwrite things. |
| *M::access_local_mut(self, frame, local).unwrap() = |
| Operand::Indirect(mplace); |
| mplace |
| } |
| &mut Operand::Indirect(mplace) => mplace, // this already was an indirect local |
| } |
| } |
| Place::Ptr(mplace) => mplace, |
| }; |
| // Return with the original layout, so that the caller can go on |
| Ok(MPlaceTy { mplace, layout: place.layout, align: place.align }) |
| } |
| |
| pub fn allocate( |
| &mut self, |
| layout: TyAndLayout<'tcx>, |
| kind: MemoryKind<M::MemoryKind>, |
| ) -> InterpResult<'tcx, MPlaceTy<'tcx, M::Provenance>> { |
| assert!(!layout.is_unsized()); |
| let ptr = self.allocate_ptr(layout.size, layout.align.abi, kind)?; |
| Ok(MPlaceTy::from_aligned_ptr(ptr.into(), layout)) |
| } |
| |
| /// Returns a wide MPlace of type `&'static [mut] str` to a new 1-aligned allocation. |
| pub fn allocate_str( |
| &mut self, |
| str: &str, |
| kind: MemoryKind<M::MemoryKind>, |
| mutbl: Mutability, |
| ) -> MPlaceTy<'tcx, M::Provenance> { |
| let ptr = self.allocate_bytes_ptr(str.as_bytes(), Align::ONE, kind, mutbl); |
| let meta = Scalar::from_machine_usize(u64::try_from(str.len()).unwrap(), self); |
| let mplace = MemPlace { ptr: ptr.into(), meta: MemPlaceMeta::Meta(meta) }; |
| |
| let ty = self.tcx.mk_ref( |
| self.tcx.lifetimes.re_static, |
| ty::TypeAndMut { ty: self.tcx.types.str_, mutbl }, |
| ); |
| let layout = self.layout_of(ty).unwrap(); |
| MPlaceTy { mplace, layout, align: layout.align.abi } |
| } |
| |
| /// Writes the discriminant of the given variant. |
| #[instrument(skip(self), level = "debug")] |
| pub fn write_discriminant( |
| &mut self, |
| variant_index: VariantIdx, |
| dest: &PlaceTy<'tcx, M::Provenance>, |
| ) -> InterpResult<'tcx> { |
| // This must be an enum or generator. |
| match dest.layout.ty.kind() { |
| ty::Adt(adt, _) => assert!(adt.is_enum()), |
| ty::Generator(..) => {} |
| _ => span_bug!( |
| self.cur_span(), |
| "write_discriminant called on non-variant-type (neither enum nor generator)" |
| ), |
| } |
| // Layout computation excludes uninhabited variants from consideration |
| // therefore there's no way to represent those variants in the given layout. |
| // Essentially, uninhabited variants do not have a tag that corresponds to their |
| // discriminant, so we cannot do anything here. |
| // When evaluating we will always error before even getting here, but ConstProp 'executes' |
| // dead code, so we cannot ICE here. |
| if dest.layout.for_variant(self, variant_index).abi.is_uninhabited() { |
| throw_ub!(UninhabitedEnumVariantWritten) |
| } |
| |
| match dest.layout.variants { |
| abi::Variants::Single { index } => { |
| assert_eq!(index, variant_index); |
| } |
| abi::Variants::Multiple { |
| tag_encoding: TagEncoding::Direct, |
| tag: tag_layout, |
| tag_field, |
| .. |
| } => { |
| // No need to validate that the discriminant here because the |
| // `TyAndLayout::for_variant()` call earlier already checks the variant is valid. |
| |
| let discr_val = |
| dest.layout.ty.discriminant_for_variant(*self.tcx, variant_index).unwrap().val; |
| |
| // raw discriminants for enums are isize or bigger during |
| // their computation, but the in-memory tag is the smallest possible |
| // representation |
| let size = tag_layout.size(self); |
| let tag_val = size.truncate(discr_val); |
| |
| let tag_dest = self.place_field(dest, tag_field)?; |
| self.write_scalar(Scalar::from_uint(tag_val, size), &tag_dest)?; |
| } |
| abi::Variants::Multiple { |
| tag_encoding: |
| TagEncoding::Niche { untagged_variant, ref niche_variants, niche_start }, |
| tag: tag_layout, |
| tag_field, |
| .. |
| } => { |
| // No need to validate that the discriminant here because the |
| // `TyAndLayout::for_variant()` call earlier already checks the variant is valid. |
| |
| if variant_index != untagged_variant { |
| let variants_start = niche_variants.start().as_u32(); |
| let variant_index_relative = variant_index |
| .as_u32() |
| .checked_sub(variants_start) |
| .expect("overflow computing relative variant idx"); |
| // We need to use machine arithmetic when taking into account `niche_start`: |
| // tag_val = variant_index_relative + niche_start_val |
| let tag_layout = self.layout_of(tag_layout.primitive().to_int_ty(*self.tcx))?; |
| let niche_start_val = ImmTy::from_uint(niche_start, tag_layout); |
| let variant_index_relative_val = |
| ImmTy::from_uint(variant_index_relative, tag_layout); |
| let tag_val = self.binary_op( |
| mir::BinOp::Add, |
| &variant_index_relative_val, |
| &niche_start_val, |
| )?; |
| // Write result. |
| let niche_dest = self.place_field(dest, tag_field)?; |
| self.write_immediate(*tag_val, &niche_dest)?; |
| } |
| } |
| } |
| |
| Ok(()) |
| } |
| |
| pub fn raw_const_to_mplace( |
| &self, |
| raw: 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(MPlaceTy::from_aligned_ptr(ptr.into(), layout)) |
| } |
| |
| /// Turn a place with a `dyn Trait` type into a place with the actual dynamic type. |
| pub(super) fn unpack_dyn_trait( |
| &self, |
| mplace: &MPlaceTy<'tcx, M::Provenance>, |
| ) -> InterpResult<'tcx, MPlaceTy<'tcx, M::Provenance>> { |
| let vtable = mplace.vtable().to_pointer(self)?; // also sanity checks the type |
| let (ty, _) = self.get_ptr_vtable(vtable)?; |
| let layout = self.layout_of(ty)?; |
| |
| let mplace = MPlaceTy { |
| mplace: MemPlace { meta: MemPlaceMeta::None, ..**mplace }, |
| layout, |
| align: layout.align.abi, |
| }; |
| Ok(mplace) |
| } |
| } |
| |
| // 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, 40); |
| static_assert_size!(MemPlaceMeta, 24); |
| static_assert_size!(MPlaceTy<'_>, 64); |
| static_assert_size!(Place, 40); |
| static_assert_size!(PlaceTy<'_>, 64); |
| // tidy-alphabetical-end |
| } |
