1167 lines
47 KiB
Rust
1167 lines
47 KiB
Rust
//! Computations on places -- field projections, going from mir::Place, and writing
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//! into a place.
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//! All high-level functions to write to memory work on places as destinations.
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use std::convert::TryFrom;
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use std::fmt::Debug;
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use std::hash::Hash;
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use rustc_macros::HashStable;
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use rustc_middle::mir;
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use rustc_middle::ty::layout::{PrimitiveExt, TyAndLayout};
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use rustc_middle::ty::{self, Ty};
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use rustc_target::abi::{Abi, Align, FieldsShape, TagEncoding};
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use rustc_target::abi::{HasDataLayout, LayoutOf, Size, VariantIdx, Variants};
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use super::{
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mir_assign_valid_types, AllocId, AllocMap, Allocation, AllocationExtra, ConstAlloc, ImmTy,
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Immediate, InterpCx, InterpResult, LocalValue, Machine, MemoryKind, OpTy, Operand, Pointer,
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PointerArithmetic, Scalar, ScalarMaybeUninit,
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};
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#[derive(Copy, Clone, Debug, Hash, PartialEq, Eq, HashStable)]
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/// Information required for the sound usage of a `MemPlace`.
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pub enum MemPlaceMeta<Tag = ()> {
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/// The unsized payload (e.g. length for slices or vtable pointer for trait objects).
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Meta(Scalar<Tag>),
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/// `Sized` types or unsized `extern type`
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None,
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/// The address of this place may not be taken. This protects the `MemPlace` from coming from
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/// a ZST Operand without a backing allocation and being converted to an integer address. This
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/// should be impossible, because you can't take the address of an operand, but this is a second
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/// protection layer ensuring that we don't mess up.
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Poison,
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}
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#[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
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rustc_data_structures::static_assert_size!(MemPlaceMeta, 24);
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impl<Tag> MemPlaceMeta<Tag> {
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pub fn unwrap_meta(self) -> Scalar<Tag> {
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match self {
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Self::Meta(s) => s,
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Self::None | Self::Poison => {
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bug!("expected wide pointer extra data (e.g. slice length or trait object vtable)")
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}
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}
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}
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fn has_meta(self) -> bool {
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match self {
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Self::Meta(_) => true,
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Self::None | Self::Poison => false,
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}
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}
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pub fn erase_tag(self) -> MemPlaceMeta<()> {
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match self {
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Self::Meta(s) => MemPlaceMeta::Meta(s.erase_tag()),
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Self::None => MemPlaceMeta::None,
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Self::Poison => MemPlaceMeta::Poison,
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}
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}
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}
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#[derive(Copy, Clone, Debug, Hash, PartialEq, Eq, HashStable)]
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pub struct MemPlace<Tag = ()> {
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/// A place may have an integral pointer for ZSTs, and since it might
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/// be turned back into a reference before ever being dereferenced.
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/// However, it may never be uninit.
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pub ptr: Scalar<Tag>,
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pub align: Align,
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/// Metadata for unsized places. Interpretation is up to the type.
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/// Must not be present for sized types, but can be missing for unsized types
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/// (e.g., `extern type`).
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pub meta: MemPlaceMeta<Tag>,
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}
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#[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
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rustc_data_structures::static_assert_size!(MemPlace, 56);
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#[derive(Copy, Clone, Debug, Hash, PartialEq, Eq, HashStable)]
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pub enum Place<Tag = ()> {
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/// A place referring to a value allocated in the `Memory` system.
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Ptr(MemPlace<Tag>),
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/// To support alloc-free locals, we are able to write directly to a local.
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/// (Without that optimization, we'd just always be a `MemPlace`.)
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Local { frame: usize, local: mir::Local },
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}
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#[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
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rustc_data_structures::static_assert_size!(Place, 64);
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#[derive(Copy, Clone, Debug)]
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pub struct PlaceTy<'tcx, Tag = ()> {
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place: Place<Tag>, // Keep this private; it helps enforce invariants.
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pub layout: TyAndLayout<'tcx>,
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}
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#[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
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rustc_data_structures::static_assert_size!(PlaceTy<'_>, 80);
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impl<'tcx, Tag> std::ops::Deref for PlaceTy<'tcx, Tag> {
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type Target = Place<Tag>;
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#[inline(always)]
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fn deref(&self) -> &Place<Tag> {
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&self.place
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}
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}
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/// A MemPlace with its layout. Constructing it is only possible in this module.
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#[derive(Copy, Clone, Debug, Hash, Eq, PartialEq)]
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pub struct MPlaceTy<'tcx, Tag = ()> {
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mplace: MemPlace<Tag>,
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pub layout: TyAndLayout<'tcx>,
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}
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#[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
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rustc_data_structures::static_assert_size!(MPlaceTy<'_>, 72);
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impl<'tcx, Tag> std::ops::Deref for MPlaceTy<'tcx, Tag> {
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type Target = MemPlace<Tag>;
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#[inline(always)]
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fn deref(&self) -> &MemPlace<Tag> {
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&self.mplace
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}
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}
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impl<'tcx, Tag> From<MPlaceTy<'tcx, Tag>> for PlaceTy<'tcx, Tag> {
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#[inline(always)]
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fn from(mplace: MPlaceTy<'tcx, Tag>) -> Self {
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PlaceTy { place: Place::Ptr(mplace.mplace), layout: mplace.layout }
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}
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}
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impl<Tag> MemPlace<Tag> {
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/// Replace ptr tag, maintain vtable tag (if any)
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#[inline]
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pub fn replace_tag(self, new_tag: Tag) -> Self {
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MemPlace { ptr: self.ptr.erase_tag().with_tag(new_tag), align: self.align, meta: self.meta }
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}
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#[inline]
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pub fn erase_tag(self) -> MemPlace {
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MemPlace { ptr: self.ptr.erase_tag(), align: self.align, meta: self.meta.erase_tag() }
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}
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#[inline(always)]
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fn from_scalar_ptr(ptr: Scalar<Tag>, align: Align) -> Self {
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MemPlace { ptr, align, meta: MemPlaceMeta::None }
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}
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#[inline(always)]
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pub fn from_ptr(ptr: Pointer<Tag>, align: Align) -> Self {
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Self::from_scalar_ptr(ptr.into(), align)
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}
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/// Turn a mplace into a (thin or wide) pointer, as a reference, pointing to the same space.
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/// This is the inverse of `ref_to_mplace`.
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#[inline(always)]
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pub fn to_ref(self) -> Immediate<Tag> {
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match self.meta {
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MemPlaceMeta::None => Immediate::Scalar(self.ptr.into()),
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MemPlaceMeta::Meta(meta) => Immediate::ScalarPair(self.ptr.into(), meta.into()),
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MemPlaceMeta::Poison => bug!(
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"MPlaceTy::dangling may never be used to produce a \
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place that will have the address of its pointee taken"
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),
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}
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}
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#[inline]
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pub fn offset(
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self,
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offset: Size,
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meta: MemPlaceMeta<Tag>,
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cx: &impl HasDataLayout,
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) -> InterpResult<'tcx, Self> {
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Ok(MemPlace {
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ptr: self.ptr.ptr_offset(offset, cx)?,
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align: self.align.restrict_for_offset(offset),
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meta,
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})
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}
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}
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impl<'tcx, Tag: Copy> MPlaceTy<'tcx, Tag> {
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/// Produces a MemPlace that works for ZST but nothing else
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#[inline]
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pub fn dangling(layout: TyAndLayout<'tcx>, cx: &impl HasDataLayout) -> Self {
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let align = layout.align.abi;
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let ptr = Scalar::from_machine_usize(align.bytes(), cx);
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// `Poison` this to make sure that the pointer value `ptr` is never observable by the program.
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MPlaceTy { mplace: MemPlace { ptr, align, meta: MemPlaceMeta::Poison }, layout }
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}
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/// Replace ptr tag, maintain vtable tag (if any)
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#[inline]
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pub fn replace_tag(&self, new_tag: Tag) -> Self {
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MPlaceTy { mplace: self.mplace.replace_tag(new_tag), layout: self.layout }
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}
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#[inline]
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pub fn offset(
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&self,
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offset: Size,
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meta: MemPlaceMeta<Tag>,
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layout: TyAndLayout<'tcx>,
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cx: &impl HasDataLayout,
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) -> InterpResult<'tcx, Self> {
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Ok(MPlaceTy { mplace: self.mplace.offset(offset, meta, cx)?, layout })
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}
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#[inline]
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fn from_aligned_ptr(ptr: Pointer<Tag>, layout: TyAndLayout<'tcx>) -> Self {
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MPlaceTy { mplace: MemPlace::from_ptr(ptr, layout.align.abi), layout }
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}
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#[inline]
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pub(super) fn len(&self, cx: &impl HasDataLayout) -> InterpResult<'tcx, u64> {
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if self.layout.is_unsized() {
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// We need to consult `meta` metadata
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match self.layout.ty.kind() {
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ty::Slice(..) | ty::Str => self.mplace.meta.unwrap_meta().to_machine_usize(cx),
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_ => bug!("len not supported on unsized type {:?}", self.layout.ty),
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}
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} else {
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// Go through the layout. There are lots of types that support a length,
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// e.g., SIMD types.
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match self.layout.fields {
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FieldsShape::Array { count, .. } => Ok(count),
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_ => bug!("len not supported on sized type {:?}", self.layout.ty),
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}
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}
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}
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#[inline]
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pub(super) fn vtable(&self) -> Scalar<Tag> {
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match self.layout.ty.kind() {
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ty::Dynamic(..) => self.mplace.meta.unwrap_meta(),
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_ => bug!("vtable not supported on type {:?}", self.layout.ty),
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}
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}
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}
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// These are defined here because they produce a place.
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impl<'tcx, Tag: Debug + Copy> OpTy<'tcx, Tag> {
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#[inline(always)]
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/// Note: do not call `as_ref` on the resulting place. This function should only be used to
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/// read from the resulting mplace, not to get its address back.
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pub fn try_as_mplace(
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&self,
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cx: &impl HasDataLayout,
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) -> Result<MPlaceTy<'tcx, Tag>, ImmTy<'tcx, Tag>> {
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match **self {
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Operand::Indirect(mplace) => Ok(MPlaceTy { mplace, layout: self.layout }),
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Operand::Immediate(_) if self.layout.is_zst() => {
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Ok(MPlaceTy::dangling(self.layout, cx))
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}
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Operand::Immediate(imm) => Err(ImmTy::from_immediate(imm, self.layout)),
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}
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}
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#[inline(always)]
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/// Note: do not call `as_ref` on the resulting place. This function should only be used to
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/// read from the resulting mplace, not to get its address back.
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pub fn assert_mem_place(&self, cx: &impl HasDataLayout) -> MPlaceTy<'tcx, Tag> {
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self.try_as_mplace(cx).unwrap()
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}
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}
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impl<Tag: Debug> Place<Tag> {
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#[inline]
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pub fn assert_mem_place(self) -> MemPlace<Tag> {
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match self {
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Place::Ptr(mplace) => mplace,
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_ => bug!("assert_mem_place: expected Place::Ptr, got {:?}", self),
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}
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}
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}
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impl<'tcx, Tag: Debug> PlaceTy<'tcx, Tag> {
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#[inline]
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pub fn assert_mem_place(self) -> MPlaceTy<'tcx, Tag> {
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MPlaceTy { mplace: self.place.assert_mem_place(), layout: self.layout }
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}
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}
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// separating the pointer tag for `impl Trait`, see https://github.com/rust-lang/rust/issues/54385
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impl<'mir, 'tcx: 'mir, Tag, M> InterpCx<'mir, 'tcx, M>
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where
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// FIXME: Working around https://github.com/rust-lang/rust/issues/54385
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Tag: Debug + Copy + Eq + Hash + 'static,
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M: Machine<'mir, 'tcx, PointerTag = Tag>,
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// FIXME: Working around https://github.com/rust-lang/rust/issues/24159
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M::MemoryMap: AllocMap<AllocId, (MemoryKind<M::MemoryKind>, Allocation<Tag, M::AllocExtra>)>,
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M::AllocExtra: AllocationExtra<Tag>,
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{
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/// Take a value, which represents a (thin or wide) reference, and make it a place.
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/// Alignment is just based on the type. This is the inverse of `MemPlace::to_ref()`.
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///
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/// Only call this if you are sure the place is "valid" (aligned and inbounds), or do not
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/// want to ever use the place for memory access!
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/// Generally prefer `deref_operand`.
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pub fn ref_to_mplace(
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&self,
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val: &ImmTy<'tcx, M::PointerTag>,
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) -> InterpResult<'tcx, MPlaceTy<'tcx, M::PointerTag>> {
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let pointee_type =
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val.layout.ty.builtin_deref(true).expect("`ref_to_mplace` called on non-ptr type").ty;
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let layout = self.layout_of(pointee_type)?;
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let (ptr, meta) = match **val {
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Immediate::Scalar(ptr) => (ptr.check_init()?, MemPlaceMeta::None),
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Immediate::ScalarPair(ptr, meta) => {
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(ptr.check_init()?, MemPlaceMeta::Meta(meta.check_init()?))
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}
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};
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let mplace = MemPlace {
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ptr,
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// We could use the run-time alignment here. For now, we do not, because
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// the point of tracking the alignment here is to make sure that the *static*
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// alignment information emitted with the loads is correct. The run-time
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// alignment can only be more restrictive.
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align: layout.align.abi,
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meta,
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};
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Ok(MPlaceTy { mplace, layout })
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}
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/// Take an operand, representing a pointer, and dereference it to a place -- that
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/// will always be a MemPlace. Lives in `place.rs` because it creates a place.
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pub fn deref_operand(
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&self,
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src: &OpTy<'tcx, M::PointerTag>,
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) -> InterpResult<'tcx, MPlaceTy<'tcx, M::PointerTag>> {
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let val = self.read_immediate(src)?;
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trace!("deref to {} on {:?}", val.layout.ty, *val);
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let place = self.ref_to_mplace(&val)?;
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self.mplace_access_checked(place, None)
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}
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/// Check if the given place is good for memory access with the given
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/// size, falling back to the layout's size if `None` (in the latter case,
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/// this must be a statically sized type).
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///
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/// On success, returns `None` for zero-sized accesses (where nothing else is
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/// left to do) and a `Pointer` to use for the actual access otherwise.
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#[inline]
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pub(super) fn check_mplace_access(
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&self,
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place: &MPlaceTy<'tcx, M::PointerTag>,
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size: Option<Size>,
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) -> InterpResult<'tcx, Option<Pointer<M::PointerTag>>> {
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let size = size.unwrap_or_else(|| {
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assert!(!place.layout.is_unsized());
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assert!(!place.meta.has_meta());
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place.layout.size
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});
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self.memory.check_ptr_access(place.ptr, size, place.align)
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}
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/// Return the "access-checked" version of this `MPlace`, where for non-ZST
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/// this is definitely a `Pointer`.
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///
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/// `force_align` must only be used when correct alignment does not matter,
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/// like in Stacked Borrows.
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pub fn mplace_access_checked(
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&self,
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mut place: MPlaceTy<'tcx, M::PointerTag>,
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force_align: Option<Align>,
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) -> InterpResult<'tcx, MPlaceTy<'tcx, M::PointerTag>> {
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let (size, align) = self
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.size_and_align_of_mplace(&place)?
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.unwrap_or((place.layout.size, place.layout.align.abi));
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assert!(place.mplace.align <= align, "dynamic alignment less strict than static one?");
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// Check (stricter) dynamic alignment, unless forced otherwise.
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place.mplace.align = force_align.unwrap_or(align);
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// When dereferencing a pointer, it must be non-NULL, aligned, and live.
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if let Some(ptr) = self.check_mplace_access(&place, Some(size))? {
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place.mplace.ptr = ptr.into();
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}
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Ok(place)
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}
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/// Force `place.ptr` to a `Pointer`.
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/// Can be helpful to avoid lots of `force_ptr` calls later, if this place is used a lot.
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pub(super) fn force_mplace_ptr(
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&self,
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mut place: MPlaceTy<'tcx, M::PointerTag>,
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) -> InterpResult<'tcx, MPlaceTy<'tcx, M::PointerTag>> {
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place.mplace.ptr = self.force_ptr(place.mplace.ptr)?.into();
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Ok(place)
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}
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/// Offset a pointer to project to a field of a struct/union. Unlike `place_field`, this is
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/// always possible without allocating, so it can take `&self`. Also return the field's layout.
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/// This supports both struct and array fields.
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///
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/// This also works for arrays, but then the `usize` index type is restricting.
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/// For indexing into arrays, use `mplace_index`.
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#[inline(always)]
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pub fn mplace_field(
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&self,
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base: &MPlaceTy<'tcx, M::PointerTag>,
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field: usize,
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) -> InterpResult<'tcx, MPlaceTy<'tcx, M::PointerTag>> {
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let offset = base.layout.fields.offset(field);
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let field_layout = base.layout.field(self, field)?;
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// Offset may need adjustment for unsized fields.
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let (meta, offset) = if field_layout.is_unsized() {
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// Re-use parent metadata to determine dynamic field layout.
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// With custom DSTS, this *will* execute user-defined code, but the same
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// happens at run-time so that's okay.
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let align = match self.size_and_align_of(&base.meta, &field_layout)? {
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Some((_, align)) => align,
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None if offset == Size::ZERO => {
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// An extern type at offset 0, we fall back to its static alignment.
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// FIXME: Once we have made decisions for how to handle size and alignment
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// of `extern type`, this should be adapted. It is just a temporary hack
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// to get some code to work that probably ought to work.
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field_layout.align.abi
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}
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None => span_bug!(
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self.cur_span(),
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"cannot compute offset for extern type field at non-0 offset"
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),
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};
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(base.meta, offset.align_to(align))
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} else {
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// base.meta could be present; we might be accessing a sized field of an unsized
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// struct.
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(MemPlaceMeta::None, offset)
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};
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|
// We do not look at `base.layout.align` nor `field_layout.align`, unlike
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// codegen -- mostly to see if we can get away with that
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base.offset(offset, meta, field_layout, self)
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}
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/// Index into an array.
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|
#[inline(always)]
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|
pub fn mplace_index(
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&self,
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base: &MPlaceTy<'tcx, M::PointerTag>,
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index: u64,
|
|
) -> InterpResult<'tcx, MPlaceTy<'tcx, M::PointerTag>> {
|
|
// Not using the layout method because we want to compute on u64
|
|
match base.layout.fields {
|
|
FieldsShape::Array { stride, .. } => {
|
|
let len = base.len(self)?;
|
|
if index >= len {
|
|
// This can only be reached in ConstProp and non-rustc-MIR.
|
|
throw_ub!(BoundsCheckFailed { len, index });
|
|
}
|
|
let offset = stride * index; // `Size` multiplication
|
|
// All fields have the same layout.
|
|
let field_layout = base.layout.field(self, 0)?;
|
|
|
|
assert!(!field_layout.is_unsized());
|
|
base.offset(offset, MemPlaceMeta::None, field_layout, self)
|
|
}
|
|
_ => span_bug!(
|
|
self.cur_span(),
|
|
"`mplace_index` called on non-array type {:?}",
|
|
base.layout.ty
|
|
),
|
|
}
|
|
}
|
|
|
|
// Iterates over all fields of an array. Much more efficient than doing the
|
|
// same by repeatedly calling `mplace_array`.
|
|
pub(super) fn mplace_array_fields(
|
|
&self,
|
|
base: &'a MPlaceTy<'tcx, Tag>,
|
|
) -> InterpResult<'tcx, impl Iterator<Item = InterpResult<'tcx, MPlaceTy<'tcx, Tag>>> + 'a>
|
|
{
|
|
let len = base.len(self)?; // also asserts that we have a type where this makes sense
|
|
let stride = match base.layout.fields {
|
|
FieldsShape::Array { stride, .. } => stride,
|
|
_ => span_bug!(self.cur_span(), "mplace_array_fields: expected an array layout"),
|
|
};
|
|
let layout = base.layout.field(self, 0)?;
|
|
let dl = &self.tcx.data_layout;
|
|
// `Size` multiplication
|
|
Ok((0..len).map(move |i| base.offset(stride * i, MemPlaceMeta::None, layout, dl)))
|
|
}
|
|
|
|
fn mplace_subslice(
|
|
&self,
|
|
base: &MPlaceTy<'tcx, M::PointerTag>,
|
|
from: u64,
|
|
to: u64,
|
|
from_end: bool,
|
|
) -> InterpResult<'tcx, MPlaceTy<'tcx, M::PointerTag>> {
|
|
let len = base.len(self)?; // also asserts that we have a type where this makes sense
|
|
let actual_to = if from_end {
|
|
if from.checked_add(to).map_or(true, |to| to > len) {
|
|
// This can only be reached in ConstProp and non-rustc-MIR.
|
|
throw_ub!(BoundsCheckFailed { len: len, index: from.saturating_add(to) });
|
|
}
|
|
len.checked_sub(to).unwrap()
|
|
} else {
|
|
to
|
|
};
|
|
|
|
// Not using layout method because that works with usize, and does not work with slices
|
|
// (that have count 0 in their layout).
|
|
let from_offset = match base.layout.fields {
|
|
FieldsShape::Array { stride, .. } => stride * from, // `Size` multiplication is checked
|
|
_ => {
|
|
span_bug!(self.cur_span(), "unexpected layout of index access: {:#?}", base.layout)
|
|
}
|
|
};
|
|
|
|
// Compute meta and new layout
|
|
let inner_len = actual_to.checked_sub(from).unwrap();
|
|
let (meta, ty) = match base.layout.ty.kind() {
|
|
// It is not nice to match on the type, but that seems to be the only way to
|
|
// implement this.
|
|
ty::Array(inner, _) => (MemPlaceMeta::None, self.tcx.mk_array(inner, inner_len)),
|
|
ty::Slice(..) => {
|
|
let len = Scalar::from_machine_usize(inner_len, self);
|
|
(MemPlaceMeta::Meta(len), base.layout.ty)
|
|
}
|
|
_ => {
|
|
span_bug!(self.cur_span(), "cannot subslice non-array type: `{:?}`", base.layout.ty)
|
|
}
|
|
};
|
|
let layout = self.layout_of(ty)?;
|
|
base.offset(from_offset, meta, layout, self)
|
|
}
|
|
|
|
pub(crate) fn mplace_downcast(
|
|
&self,
|
|
base: &MPlaceTy<'tcx, M::PointerTag>,
|
|
variant: VariantIdx,
|
|
) -> InterpResult<'tcx, MPlaceTy<'tcx, M::PointerTag>> {
|
|
// Downcasts only change the layout
|
|
assert!(!base.meta.has_meta());
|
|
Ok(MPlaceTy { layout: base.layout.for_variant(self, variant), ..*base })
|
|
}
|
|
|
|
/// Project into an mplace
|
|
pub(super) fn mplace_projection(
|
|
&self,
|
|
base: &MPlaceTy<'tcx, M::PointerTag>,
|
|
proj_elem: mir::PlaceElem<'tcx>,
|
|
) -> InterpResult<'tcx, MPlaceTy<'tcx, M::PointerTag>> {
|
|
use rustc_middle::mir::ProjectionElem::*;
|
|
Ok(match proj_elem {
|
|
Field(field, _) => self.mplace_field(base, field.index())?,
|
|
Downcast(_, variant) => self.mplace_downcast(base, variant)?,
|
|
Deref => self.deref_operand(&base.into())?,
|
|
|
|
Index(local) => {
|
|
let layout = self.layout_of(self.tcx.types.usize)?;
|
|
let n = self.access_local(self.frame(), local, Some(layout))?;
|
|
let n = self.read_scalar(&n)?;
|
|
let n = u64::try_from(
|
|
self.force_bits(n.check_init()?, self.tcx.data_layout.pointer_size)?,
|
|
)
|
|
.unwrap();
|
|
self.mplace_index(base, n)?
|
|
}
|
|
|
|
ConstantIndex { offset, min_length, from_end } => {
|
|
let n = base.len(self)?;
|
|
if n < min_length {
|
|
// This can only be reached in ConstProp and non-rustc-MIR.
|
|
throw_ub!(BoundsCheckFailed { len: min_length, index: n });
|
|
}
|
|
|
|
let index = if from_end {
|
|
assert!(0 < offset && offset <= min_length);
|
|
n.checked_sub(offset).unwrap()
|
|
} else {
|
|
assert!(offset < min_length);
|
|
offset
|
|
};
|
|
|
|
self.mplace_index(base, index)?
|
|
}
|
|
|
|
Subslice { from, to, from_end } => self.mplace_subslice(base, from, to, from_end)?,
|
|
})
|
|
}
|
|
|
|
/// Gets the place of a field inside the place, and also the field's type.
|
|
/// Just a convenience function, but used quite a bit.
|
|
/// This is the only projection that might have a side-effect: We cannot project
|
|
/// into the field of a local `ScalarPair`, we have to first allocate it.
|
|
pub fn place_field(
|
|
&mut self,
|
|
base: &PlaceTy<'tcx, M::PointerTag>,
|
|
field: usize,
|
|
) -> InterpResult<'tcx, PlaceTy<'tcx, M::PointerTag>> {
|
|
// FIXME: We could try to be smarter and avoid allocation for fields that span the
|
|
// entire place.
|
|
let mplace = self.force_allocation(base)?;
|
|
Ok(self.mplace_field(&mplace, field)?.into())
|
|
}
|
|
|
|
pub fn place_index(
|
|
&mut self,
|
|
base: &PlaceTy<'tcx, M::PointerTag>,
|
|
index: u64,
|
|
) -> InterpResult<'tcx, PlaceTy<'tcx, M::PointerTag>> {
|
|
let mplace = self.force_allocation(base)?;
|
|
Ok(self.mplace_index(&mplace, index)?.into())
|
|
}
|
|
|
|
pub fn place_downcast(
|
|
&self,
|
|
base: &PlaceTy<'tcx, M::PointerTag>,
|
|
variant: VariantIdx,
|
|
) -> InterpResult<'tcx, PlaceTy<'tcx, M::PointerTag>> {
|
|
// Downcast just changes the layout
|
|
Ok(match base.place {
|
|
Place::Ptr(mplace) => {
|
|
self.mplace_downcast(&MPlaceTy { mplace, layout: base.layout }, variant)?.into()
|
|
}
|
|
Place::Local { .. } => {
|
|
let layout = base.layout.for_variant(self, variant);
|
|
PlaceTy { layout, ..*base }
|
|
}
|
|
})
|
|
}
|
|
|
|
/// Projects into a place.
|
|
pub fn place_projection(
|
|
&mut self,
|
|
base: &PlaceTy<'tcx, M::PointerTag>,
|
|
&proj_elem: &mir::ProjectionElem<mir::Local, Ty<'tcx>>,
|
|
) -> InterpResult<'tcx, PlaceTy<'tcx, M::PointerTag>> {
|
|
use rustc_middle::mir::ProjectionElem::*;
|
|
Ok(match proj_elem {
|
|
Field(field, _) => self.place_field(base, field.index())?,
|
|
Downcast(_, variant) => self.place_downcast(base, variant)?,
|
|
Deref => self.deref_operand(&self.place_to_op(base)?)?.into(),
|
|
// For the other variants, we have to force an allocation.
|
|
// This matches `operand_projection`.
|
|
Subslice { .. } | ConstantIndex { .. } | Index(_) => {
|
|
let mplace = self.force_allocation(base)?;
|
|
self.mplace_projection(&mplace, proj_elem)?.into()
|
|
}
|
|
})
|
|
}
|
|
|
|
/// 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_for_read`.
|
|
pub fn eval_place(
|
|
&mut self,
|
|
place: mir::Place<'tcx>,
|
|
) -> InterpResult<'tcx, PlaceTy<'tcx, M::PointerTag>> {
|
|
let mut place_ty = PlaceTy {
|
|
// This works even for dead/uninitialized locals; we check further when writing
|
|
place: Place::Local { frame: self.frame_idx(), local: place.local },
|
|
layout: self.layout_of_local(self.frame(), place.local, None)?,
|
|
};
|
|
|
|
for elem in place.projection.iter() {
|
|
place_ty = self.place_projection(&place_ty, &elem)?
|
|
}
|
|
|
|
trace!("{:?}", self.dump_place(place_ty.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(
|
|
place.ty(&self.frame().body.local_decls, *self.tcx).ty
|
|
))?,
|
|
place_ty.layout,
|
|
));
|
|
Ok(place_ty)
|
|
}
|
|
|
|
/// Write a scalar to a place
|
|
#[inline(always)]
|
|
pub fn write_scalar(
|
|
&mut self,
|
|
val: impl Into<ScalarMaybeUninit<M::PointerTag>>,
|
|
dest: &PlaceTy<'tcx, M::PointerTag>,
|
|
) -> InterpResult<'tcx> {
|
|
self.write_immediate(Immediate::Scalar(val.into()), dest)
|
|
}
|
|
|
|
/// Write an immediate to a place
|
|
#[inline(always)]
|
|
pub fn write_immediate(
|
|
&mut self,
|
|
src: Immediate<M::PointerTag>,
|
|
dest: &PlaceTy<'tcx, M::PointerTag>,
|
|
) -> 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 an `Immediate` to memory.
|
|
#[inline(always)]
|
|
pub fn write_immediate_to_mplace(
|
|
&mut self,
|
|
src: Immediate<M::PointerTag>,
|
|
dest: &MPlaceTy<'tcx, M::PointerTag>,
|
|
) -> InterpResult<'tcx> {
|
|
self.write_immediate_to_mplace_no_validate(src, dest)?;
|
|
|
|
if M::enforce_validity(self) {
|
|
// Data got changed, better make sure it matches the type!
|
|
self.validate_operand(&dest.into())?;
|
|
}
|
|
|
|
Ok(())
|
|
}
|
|
|
|
/// 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::PointerTag>,
|
|
dest: &PlaceTy<'tcx, M::PointerTag>,
|
|
) -> InterpResult<'tcx> {
|
|
if cfg!(debug_assertions) {
|
|
// This is a very common path, avoid some checks in release mode
|
|
assert!(!dest.layout.is_unsized(), "Cannot write unsized data");
|
|
match src {
|
|
Immediate::Scalar(ScalarMaybeUninit::Scalar(Scalar::Ptr(_))) => assert_eq!(
|
|
self.pointer_size(),
|
|
dest.layout.size,
|
|
"Size mismatch when writing pointer"
|
|
),
|
|
Immediate::Scalar(ScalarMaybeUninit::Scalar(Scalar::Int(int))) => {
|
|
assert_eq!(int.size(), dest.layout.size, "Size mismatch when writing bits")
|
|
}
|
|
Immediate::Scalar(ScalarMaybeUninit::Uninit) => {} // uninit can have any size
|
|
Immediate::ScalarPair(_, _) => {
|
|
// FIXME: Can we check anything here?
|
|
}
|
|
}
|
|
}
|
|
trace!("write_immediate: {:?} <- {:?}: {}", *dest, src, dest.layout.ty);
|
|
|
|
// See if we can avoid an allocation. This is the counterpart to `try_read_immediate`,
|
|
// but not factored as a separate function.
|
|
let mplace = match dest.place {
|
|
Place::Local { frame, local } => {
|
|
match M::access_local_mut(self, frame, local)? {
|
|
Ok(local) => {
|
|
// Local can be updated in-place.
|
|
*local = LocalValue::Live(Operand::Immediate(src));
|
|
return Ok(());
|
|
}
|
|
Err(mplace) => {
|
|
// The local is in memory, go on below.
|
|
mplace
|
|
}
|
|
}
|
|
}
|
|
Place::Ptr(mplace) => mplace, // already referring to memory
|
|
};
|
|
let dest = MPlaceTy { mplace, layout: dest.layout };
|
|
|
|
// This is already in memory, write there.
|
|
self.write_immediate_to_mplace_no_validate(src, &dest)
|
|
}
|
|
|
|
/// Write an immediate to memory.
|
|
/// If you use this you are responsible for validating that things got copied at the
|
|
/// right type.
|
|
fn write_immediate_to_mplace_no_validate(
|
|
&mut self,
|
|
value: Immediate<M::PointerTag>,
|
|
dest: &MPlaceTy<'tcx, M::PointerTag>,
|
|
) -> 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 `src_val` 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.
|
|
|
|
// Invalid places are a thing: the return place of a diverging function
|
|
let ptr = match self.check_mplace_access(dest, None)? {
|
|
Some(ptr) => ptr,
|
|
None => return Ok(()), // zero-sized access
|
|
};
|
|
|
|
let tcx = *self.tcx;
|
|
// FIXME: We should check that there are dest.layout.size many bytes available in
|
|
// memory. The code below is not sufficient, with enough padding it might not
|
|
// cover all the bytes!
|
|
match value {
|
|
Immediate::Scalar(scalar) => {
|
|
match dest.layout.abi {
|
|
Abi::Scalar(_) => {} // fine
|
|
_ => span_bug!(
|
|
self.cur_span(),
|
|
"write_immediate_to_mplace: invalid Scalar layout: {:#?}",
|
|
dest.layout
|
|
),
|
|
}
|
|
self.memory.get_raw_mut(ptr.alloc_id)?.write_scalar(
|
|
&tcx,
|
|
ptr,
|
|
scalar,
|
|
dest.layout.size,
|
|
)
|
|
}
|
|
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 (a, b) = match dest.layout.abi {
|
|
Abi::ScalarPair(ref a, ref b) => (&a.value, &b.value),
|
|
_ => span_bug!(
|
|
self.cur_span(),
|
|
"write_immediate_to_mplace: invalid ScalarPair layout: {:#?}",
|
|
dest.layout
|
|
),
|
|
};
|
|
let (a_size, b_size) = (a.size(self), b.size(self));
|
|
let b_offset = a_size.align_to(b.align(self).abi);
|
|
let b_ptr = ptr.offset(b_offset, self)?;
|
|
|
|
// 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.
|
|
|
|
self.memory.get_raw_mut(ptr.alloc_id)?.write_scalar(&tcx, ptr, a_val, a_size)?;
|
|
self.memory.get_raw_mut(b_ptr.alloc_id)?.write_scalar(&tcx, b_ptr, b_val, b_size)
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Copies the data from an operand to a place. This does not support transmuting!
|
|
/// Use `copy_op_transmute` if the layouts could disagree.
|
|
#[inline(always)]
|
|
pub fn copy_op(
|
|
&mut self,
|
|
src: &OpTy<'tcx, M::PointerTag>,
|
|
dest: &PlaceTy<'tcx, M::PointerTag>,
|
|
) -> InterpResult<'tcx> {
|
|
self.copy_op_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(())
|
|
}
|
|
|
|
/// Copies the data from an operand to a place. This does not support transmuting!
|
|
/// Use `copy_op_transmute` if the layouts could disagree.
|
|
/// Also, if you use this you are responsible for validating that things get copied at the
|
|
/// right type.
|
|
fn copy_op_no_validate(
|
|
&mut self,
|
|
src: &OpTy<'tcx, M::PointerTag>,
|
|
dest: &PlaceTy<'tcx, M::PointerTag>,
|
|
) -> 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.
|
|
if !mir_assign_valid_types(*self.tcx, self.param_env, src.layout, dest.layout) {
|
|
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.try_read_immediate(src)? {
|
|
Ok(src_val) => {
|
|
assert!(!src.layout.is_unsized(), "cannot have unsized immediates");
|
|
// Yay, we got a value that we can write directly.
|
|
// FIXME: Add a check to make sure that if `src` is indirect,
|
|
// it does not overlap with `dest`.
|
|
return self.write_immediate_no_validate(*src_val, dest);
|
|
}
|
|
Err(mplace) => mplace,
|
|
};
|
|
// Slow path, this does not fit into an immediate. Just memcpy.
|
|
trace!("copy_op: {:?} <- {:?}: {}", *dest, src, dest.layout.ty);
|
|
|
|
// This interprets `src.meta` with the `dest` local's layout, if an unsized local
|
|
// is being initialized!
|
|
let (dest, size) = self.force_allocation_maybe_sized(dest, src.meta)?;
|
|
let size = size.unwrap_or_else(|| {
|
|
assert!(
|
|
!dest.layout.is_unsized(),
|
|
"Cannot copy into already initialized unsized place"
|
|
);
|
|
dest.layout.size
|
|
});
|
|
assert_eq!(src.meta, dest.meta, "Can only copy between equally-sized instances");
|
|
|
|
let src = self
|
|
.check_mplace_access(&src, Some(size))
|
|
.expect("places should be checked on creation");
|
|
let dest = self
|
|
.check_mplace_access(&dest, Some(size))
|
|
.expect("places should be checked on creation");
|
|
let (src_ptr, dest_ptr) = match (src, dest) {
|
|
(Some(src_ptr), Some(dest_ptr)) => (src_ptr, dest_ptr),
|
|
(None, None) => return Ok(()), // zero-sized copy
|
|
_ => bug!("The pointers should both be Some or both None"),
|
|
};
|
|
|
|
self.memory.copy(src_ptr, dest_ptr, size, /*nonoverlapping*/ true)
|
|
}
|
|
|
|
/// Copies the data from an operand to a place. The layouts may disagree, but they must
|
|
/// have the same size.
|
|
pub fn copy_op_transmute(
|
|
&mut self,
|
|
src: &OpTy<'tcx, M::PointerTag>,
|
|
dest: &PlaceTy<'tcx, M::PointerTag>,
|
|
) -> InterpResult<'tcx> {
|
|
if mir_assign_valid_types(*self.tcx, self.param_env, src.layout, dest.layout) {
|
|
// Fast path: Just use normal `copy_op`
|
|
return self.copy_op(src, dest);
|
|
}
|
|
// We still require the sizes to match.
|
|
if src.layout.size != dest.layout.size {
|
|
// FIXME: This should be an assert instead of an error, but if we transmute within an
|
|
// array length computation, `typeck` may not have yet been run and errored out. In fact
|
|
// most likey we *are* running `typeck` right now. Investigate whether we can bail out
|
|
// on `typeck_results().has_errors` at all const eval entry points.
|
|
debug!("Size mismatch when transmuting!\nsrc: {:#?}\ndest: {:#?}", src, dest);
|
|
self.tcx.sess.delay_span_bug(
|
|
self.cur_span(),
|
|
"size-changing transmute, should have been caught by transmute checking",
|
|
);
|
|
throw_inval!(TransmuteSizeDiff(src.layout.ty, dest.layout.ty));
|
|
}
|
|
// Unsized copies rely on interpreting `src.meta` with `dest.layout`, we want
|
|
// to avoid that here.
|
|
assert!(
|
|
!src.layout.is_unsized() && !dest.layout.is_unsized(),
|
|
"Cannot transmute unsized data"
|
|
);
|
|
|
|
// The hard case is `ScalarPair`. `src` is already read from memory in this case,
|
|
// using `src.layout` to figure out which bytes to use for the 1st and 2nd field.
|
|
// We have to write them to `dest` at the offsets they were *read at*, which is
|
|
// not necessarily the same as the offsets in `dest.layout`!
|
|
// Hence we do the copy with the source layout on both sides. We also make sure to write
|
|
// into memory, because if `dest` is a local we would not even have a way to write
|
|
// at the `src` offsets; the fact that we came from a different layout would
|
|
// just be lost.
|
|
let dest = self.force_allocation(dest)?;
|
|
self.copy_op_no_validate(
|
|
src,
|
|
&PlaceTy::from(MPlaceTy { mplace: *dest, layout: src.layout }),
|
|
)?;
|
|
|
|
if M::enforce_validity(self) {
|
|
// Data got changed, better make sure it matches the type!
|
|
self.validate_operand(&dest.into())?;
|
|
}
|
|
|
|
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`.
|
|
///
|
|
/// This supports unsized types and returns the computed size to avoid some
|
|
/// redundant computation when copying; use `force_allocation` for a simpler, sized-only
|
|
/// version.
|
|
pub fn force_allocation_maybe_sized(
|
|
&mut self,
|
|
place: &PlaceTy<'tcx, M::PointerTag>,
|
|
meta: MemPlaceMeta<M::PointerTag>,
|
|
) -> InterpResult<'tcx, (MPlaceTy<'tcx, M::PointerTag>, Option<Size>)> {
|
|
let (mplace, size) = match place.place {
|
|
Place::Local { frame, local } => {
|
|
match M::access_local_mut(self, frame, local)? {
|
|
Ok(&mut 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)?;
|
|
// We also need to support unsized types, and hence cannot use `allocate`.
|
|
let (size, align) = self
|
|
.size_and_align_of(&meta, &local_layout)?
|
|
.expect("Cannot allocate for non-dyn-sized type");
|
|
let ptr = self.memory.allocate(size, align, MemoryKind::Stack);
|
|
let mplace = MemPlace { ptr: ptr.into(), align, meta };
|
|
if let LocalValue::Live(Operand::Immediate(value)) = local_val {
|
|
// Preserve old value.
|
|
// We don't have to validate as we can assume the local
|
|
// was already valid for its type.
|
|
let mplace = MPlaceTy { mplace, layout: local_layout };
|
|
self.write_immediate_to_mplace_no_validate(value, &mplace)?;
|
|
}
|
|
// Now we can call `access_mut` again, asserting it goes well,
|
|
// and actually overwrite things.
|
|
*M::access_local_mut(self, frame, local).unwrap().unwrap() =
|
|
LocalValue::Live(Operand::Indirect(mplace));
|
|
(mplace, Some(size))
|
|
}
|
|
Err(mplace) => (mplace, None), // this already was an indirect local
|
|
}
|
|
}
|
|
Place::Ptr(mplace) => (mplace, None),
|
|
};
|
|
// Return with the original layout, so that the caller can go on
|
|
Ok((MPlaceTy { mplace, layout: place.layout }, size))
|
|
}
|
|
|
|
#[inline(always)]
|
|
pub fn force_allocation(
|
|
&mut self,
|
|
place: &PlaceTy<'tcx, M::PointerTag>,
|
|
) -> InterpResult<'tcx, MPlaceTy<'tcx, M::PointerTag>> {
|
|
Ok(self.force_allocation_maybe_sized(place, MemPlaceMeta::None)?.0)
|
|
}
|
|
|
|
pub fn allocate(
|
|
&mut self,
|
|
layout: TyAndLayout<'tcx>,
|
|
kind: MemoryKind<M::MemoryKind>,
|
|
) -> MPlaceTy<'tcx, M::PointerTag> {
|
|
let ptr = self.memory.allocate(layout.size, layout.align.abi, kind);
|
|
MPlaceTy::from_aligned_ptr(ptr, layout)
|
|
}
|
|
|
|
/// Returns a wide MPlace.
|
|
pub fn allocate_str(
|
|
&mut self,
|
|
str: &str,
|
|
kind: MemoryKind<M::MemoryKind>,
|
|
) -> MPlaceTy<'tcx, M::PointerTag> {
|
|
let ptr = self.memory.allocate_bytes(str.as_bytes(), kind);
|
|
let meta = Scalar::from_machine_usize(u64::try_from(str.len()).unwrap(), self);
|
|
let mplace = MemPlace {
|
|
ptr: ptr.into(),
|
|
align: Align::from_bytes(1).unwrap(),
|
|
meta: MemPlaceMeta::Meta(meta),
|
|
};
|
|
|
|
let layout = self.layout_of(self.tcx.mk_static_str()).unwrap();
|
|
MPlaceTy { mplace, layout }
|
|
}
|
|
|
|
/// Writes the discriminant of the given variant.
|
|
pub fn write_discriminant(
|
|
&mut self,
|
|
variant_index: VariantIdx,
|
|
dest: &PlaceTy<'tcx, M::PointerTag>,
|
|
) -> InterpResult<'tcx> {
|
|
// Layout computation excludes uninhabited variants from consideration
|
|
// therefore there's no way to represent those variants in the given layout.
|
|
if dest.layout.for_variant(self, variant_index).abi.is_uninhabited() {
|
|
throw_ub!(Unreachable);
|
|
}
|
|
|
|
match dest.layout.variants {
|
|
Variants::Single { index } => {
|
|
assert_eq!(index, variant_index);
|
|
}
|
|
Variants::Multiple {
|
|
tag_encoding: TagEncoding::Direct,
|
|
tag: ref 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.value.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)?;
|
|
}
|
|
Variants::Multiple {
|
|
tag_encoding:
|
|
TagEncoding::Niche { dataful_variant, ref niche_variants, niche_start },
|
|
tag: ref 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 != dataful_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.value.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::PointerTag>> {
|
|
// 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, layout))
|
|
}
|
|
|
|
/// Turn a place with a `dyn Trait` type into a place with the actual dynamic type.
|
|
/// Also return some more information so drop doesn't have to run the same code twice.
|
|
pub(super) fn unpack_dyn_trait(
|
|
&self,
|
|
mplace: &MPlaceTy<'tcx, M::PointerTag>,
|
|
) -> InterpResult<'tcx, (ty::Instance<'tcx>, MPlaceTy<'tcx, M::PointerTag>)> {
|
|
let vtable = mplace.vtable(); // also sanity checks the type
|
|
let (instance, ty) = self.read_drop_type_from_vtable(vtable)?;
|
|
let layout = self.layout_of(ty)?;
|
|
|
|
// More sanity checks
|
|
if cfg!(debug_assertions) {
|
|
let (size, align) = self.read_size_and_align_from_vtable(vtable)?;
|
|
assert_eq!(size, layout.size);
|
|
// only ABI alignment is preserved
|
|
assert_eq!(align, layout.align.abi);
|
|
}
|
|
|
|
let mplace = MPlaceTy { mplace: MemPlace { meta: MemPlaceMeta::None, ..**mplace }, layout };
|
|
Ok((instance, mplace))
|
|
}
|
|
}
|