| use std::cell::Cell; |
| use std::fmt; |
| use std::mem; |
| |
| use rustc_data_structures::fx::FxHashMap; |
| use rustc_data_structures::stable_hasher::{HashStable, StableHasher}; |
| use rustc_hir::{self as hir, def::DefKind, def_id::DefId, definitions::DefPathData}; |
| use rustc_index::vec::IndexVec; |
| use rustc_macros::HashStable; |
| use rustc_middle::ich::StableHashingContext; |
| use rustc_middle::mir; |
| use rustc_middle::mir::interpret::{ |
| sign_extend, truncate, GlobalId, InterpResult, Pointer, Scalar, |
| }; |
| use rustc_middle::ty::layout::{self, TyAndLayout}; |
| use rustc_middle::ty::{ |
| self, query::TyCtxtAt, subst::SubstsRef, ParamEnv, Ty, TyCtxt, TypeFoldable, |
| }; |
| use rustc_span::{Pos, Span}; |
| use rustc_target::abi::{Align, HasDataLayout, LayoutOf, Size, TargetDataLayout}; |
| |
| use super::{ |
| Immediate, MPlaceTy, Machine, MemPlace, MemPlaceMeta, Memory, Operand, Place, PlaceTy, |
| ScalarMaybeUninit, StackPopJump, |
| }; |
| use crate::transform::validate::equal_up_to_regions; |
| use crate::util::storage::AlwaysLiveLocals; |
| |
| pub struct InterpCx<'mir, 'tcx, M: Machine<'mir, 'tcx>> { |
| /// Stores the `Machine` instance. |
| /// |
| /// Note: the stack is provided by the machine. |
| pub machine: M, |
| |
| /// The results of the type checker, from rustc. |
| /// The span in this is the "root" of the evaluation, i.e., the const |
| /// we are evaluating (if this is CTFE). |
| pub tcx: TyCtxtAt<'tcx>, |
| |
| /// Bounds in scope for polymorphic evaluations. |
| pub(crate) param_env: ty::ParamEnv<'tcx>, |
| |
| /// The virtual memory system. |
| pub memory: Memory<'mir, 'tcx, M>, |
| |
| /// A cache for deduplicating vtables |
| pub(super) vtables: |
| FxHashMap<(Ty<'tcx>, Option<ty::PolyExistentialTraitRef<'tcx>>), Pointer<M::PointerTag>>, |
| } |
| |
| // The Phantomdata exists to prevent this type from being `Send`. If it were sent across a thread |
| // boundary and dropped in the other thread, it would exit the span in the other thread. |
| struct SpanGuard(tracing::Span, std::marker::PhantomData<*const u8>); |
| |
| impl SpanGuard { |
| /// By default a `SpanGuard` does nothing. |
| fn new() -> Self { |
| Self(tracing::Span::none(), std::marker::PhantomData) |
| } |
| |
| /// If a span is entered, we exit the previous span (if any, normally none) and enter the |
| /// new span. This is mainly so we don't have to use `Option` for the `tracing_span` field of |
| /// `Frame` by creating a dummy span to being with and then entering it once the frame has |
| /// been pushed. |
| fn enter(&mut self, span: tracing::Span) { |
| // This executes the destructor on the previous instance of `SpanGuard`, ensuring that |
| // we never enter or exit more spans than vice versa. Unless you `mem::leak`, then we |
| // can't protect the tracing stack, but that'll just lead to weird logging, no actual |
| // problems. |
| *self = Self(span, std::marker::PhantomData); |
| self.0.with_subscriber(|(id, dispatch)| { |
| dispatch.enter(id); |
| }); |
| } |
| } |
| |
| impl Drop for SpanGuard { |
| fn drop(&mut self) { |
| self.0.with_subscriber(|(id, dispatch)| { |
| dispatch.exit(id); |
| }); |
| } |
| } |
| |
| /// A stack frame. |
| pub struct Frame<'mir, 'tcx, Tag = (), Extra = ()> { |
| //////////////////////////////////////////////////////////////////////////////// |
| // Function and callsite information |
| //////////////////////////////////////////////////////////////////////////////// |
| /// The MIR for the function called on this frame. |
| pub body: &'mir mir::Body<'tcx>, |
| |
| /// The def_id and substs of the current function. |
| pub instance: ty::Instance<'tcx>, |
| |
| /// Extra data for the machine. |
| pub extra: Extra, |
| |
| //////////////////////////////////////////////////////////////////////////////// |
| // Return place and locals |
| //////////////////////////////////////////////////////////////////////////////// |
| /// Work to perform when returning from this function. |
| pub return_to_block: StackPopCleanup, |
| |
| /// The location where the result of the current stack frame should be written to, |
| /// and its layout in the caller. |
| pub return_place: Option<PlaceTy<'tcx, Tag>>, |
| |
| /// The list of locals for this stack frame, stored in order as |
| /// `[return_ptr, arguments..., variables..., temporaries...]`. |
| /// The locals are stored as `Option<Value>`s. |
| /// `None` represents a local that is currently dead, while a live local |
| /// can either directly contain `Scalar` or refer to some part of an `Allocation`. |
| pub locals: IndexVec<mir::Local, LocalState<'tcx, Tag>>, |
| |
| /// The span of the `tracing` crate is stored here. |
| /// When the guard is dropped, the span is exited. This gives us |
| /// a full stack trace on all tracing statements. |
| tracing_span: SpanGuard, |
| |
| //////////////////////////////////////////////////////////////////////////////// |
| // Current position within the function |
| //////////////////////////////////////////////////////////////////////////////// |
| /// If this is `Err`, we are not currently executing any particular statement in |
| /// this frame (can happen e.g. during frame initialization, and during unwinding on |
| /// frames without cleanup code). |
| /// We basically abuse `Result` as `Either`. |
| pub(super) loc: Result<mir::Location, Span>, |
| } |
| |
| /// What we store about a frame in an interpreter backtrace. |
| #[derive(Debug)] |
| pub struct FrameInfo<'tcx> { |
| pub instance: ty::Instance<'tcx>, |
| pub span: Span, |
| pub lint_root: Option<hir::HirId>, |
| } |
| |
| #[derive(Clone, Eq, PartialEq, Debug, HashStable)] // Miri debug-prints these |
| pub enum StackPopCleanup { |
| /// Jump to the next block in the caller, or cause UB if None (that's a function |
| /// that may never return). Also store layout of return place so |
| /// we can validate it at that layout. |
| /// `ret` stores the block we jump to on a normal return, while `unwind` |
| /// stores the block used for cleanup during unwinding. |
| Goto { ret: Option<mir::BasicBlock>, unwind: Option<mir::BasicBlock> }, |
| /// Just do nothing: Used by Main and for the `box_alloc` hook in miri. |
| /// `cleanup` says whether locals are deallocated. Static computation |
| /// wants them leaked to intern what they need (and just throw away |
| /// the entire `ecx` when it is done). |
| None { cleanup: bool }, |
| } |
| |
| /// State of a local variable including a memoized layout |
| #[derive(Clone, PartialEq, Eq, HashStable)] |
| pub struct LocalState<'tcx, Tag = ()> { |
| pub value: LocalValue<Tag>, |
| /// Don't modify if `Some`, this is only used to prevent computing the layout twice |
| #[stable_hasher(ignore)] |
| pub layout: Cell<Option<TyAndLayout<'tcx>>>, |
| } |
| |
| /// Current value of a local variable |
| #[derive(Copy, Clone, PartialEq, Eq, Debug, HashStable)] // Miri debug-prints these |
| pub enum LocalValue<Tag = ()> { |
| /// This local is not currently alive, and cannot be used at all. |
| Dead, |
| /// This local is alive but not yet initialized. It can be written to |
| /// but not read from or its address taken. Locals get initialized on |
| /// first write because for unsized locals, we do not know their size |
| /// before that. |
| Uninitialized, |
| /// A normal, live local. |
| /// Mostly for convenience, we re-use the `Operand` type here. |
| /// This is an optimization over just always having a pointer here; |
| /// we can thus avoid doing an allocation when the local just stores |
| /// immediate values *and* never has its address taken. |
| Live(Operand<Tag>), |
| } |
| |
| impl<'tcx, Tag: Copy + 'static> LocalState<'tcx, Tag> { |
| /// Read the local's value or error if the local is not yet live or not live anymore. |
| /// |
| /// Note: This may only be invoked from the `Machine::access_local` hook and not from |
| /// anywhere else. You may be invalidating machine invariants if you do! |
| pub fn access(&self) -> InterpResult<'tcx, Operand<Tag>> { |
| match self.value { |
| LocalValue::Dead => throw_ub!(DeadLocal), |
| LocalValue::Uninitialized => { |
| bug!("The type checker should prevent reading from a never-written local") |
| } |
| LocalValue::Live(val) => Ok(val), |
| } |
| } |
| |
| /// Overwrite the local. If the local can be overwritten in place, return a reference |
| /// to do so; otherwise return the `MemPlace` to consult instead. |
| /// |
| /// Note: This may only be invoked from the `Machine::access_local_mut` hook and not from |
| /// anywhere else. You may be invalidating machine invariants if you do! |
| pub fn access_mut( |
| &mut self, |
| ) -> InterpResult<'tcx, Result<&mut LocalValue<Tag>, MemPlace<Tag>>> { |
| match self.value { |
| LocalValue::Dead => throw_ub!(DeadLocal), |
| LocalValue::Live(Operand::Indirect(mplace)) => Ok(Err(mplace)), |
| ref mut |
| local @ (LocalValue::Live(Operand::Immediate(_)) | LocalValue::Uninitialized) => { |
| Ok(Ok(local)) |
| } |
| } |
| } |
| } |
| |
| impl<'mir, 'tcx, Tag> Frame<'mir, 'tcx, Tag> { |
| pub fn with_extra<Extra>(self, extra: Extra) -> Frame<'mir, 'tcx, Tag, Extra> { |
| Frame { |
| body: self.body, |
| instance: self.instance, |
| return_to_block: self.return_to_block, |
| return_place: self.return_place, |
| locals: self.locals, |
| loc: self.loc, |
| extra, |
| tracing_span: self.tracing_span, |
| } |
| } |
| } |
| |
| impl<'mir, 'tcx, Tag, Extra> Frame<'mir, 'tcx, Tag, Extra> { |
| /// Return the `SourceInfo` of the current instruction. |
| pub fn current_source_info(&self) -> Option<&mir::SourceInfo> { |
| self.loc.ok().map(|loc| self.body.source_info(loc)) |
| } |
| |
| pub fn current_span(&self) -> Span { |
| match self.loc { |
| Ok(loc) => self.body.source_info(loc).span, |
| Err(span) => span, |
| } |
| } |
| } |
| |
| impl<'tcx> fmt::Display for FrameInfo<'tcx> { |
| fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
| ty::tls::with(|tcx| { |
| if tcx.def_key(self.instance.def_id()).disambiguated_data.data |
| == DefPathData::ClosureExpr |
| { |
| write!(f, "inside closure")?; |
| } else { |
| write!(f, "inside `{}`", self.instance)?; |
| } |
| if !self.span.is_dummy() { |
| let lo = tcx.sess.source_map().lookup_char_pos(self.span.lo()); |
| write!(f, " at {}:{}:{}", lo.file.name, lo.line, lo.col.to_usize() + 1)?; |
| } |
| Ok(()) |
| }) |
| } |
| } |
| |
| impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> HasDataLayout for InterpCx<'mir, 'tcx, M> { |
| #[inline] |
| fn data_layout(&self) -> &TargetDataLayout { |
| &self.tcx.data_layout |
| } |
| } |
| |
| impl<'mir, 'tcx, M> layout::HasTyCtxt<'tcx> for InterpCx<'mir, 'tcx, M> |
| where |
| M: Machine<'mir, 'tcx>, |
| { |
| #[inline] |
| fn tcx(&self) -> TyCtxt<'tcx> { |
| *self.tcx |
| } |
| } |
| |
| impl<'mir, 'tcx, M> layout::HasParamEnv<'tcx> for InterpCx<'mir, 'tcx, M> |
| where |
| M: Machine<'mir, 'tcx>, |
| { |
| fn param_env(&self) -> ty::ParamEnv<'tcx> { |
| self.param_env |
| } |
| } |
| |
| impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> LayoutOf for InterpCx<'mir, 'tcx, M> { |
| type Ty = Ty<'tcx>; |
| type TyAndLayout = InterpResult<'tcx, TyAndLayout<'tcx>>; |
| |
| #[inline] |
| fn layout_of(&self, ty: Ty<'tcx>) -> Self::TyAndLayout { |
| self.tcx |
| .layout_of(self.param_env.and(ty)) |
| .map_err(|layout| err_inval!(Layout(layout)).into()) |
| } |
| } |
| |
| /// Test if it is valid for a MIR assignment to assign `src`-typed place to `dest`-typed value. |
| /// This test should be symmetric, as it is primarily about layout compatibility. |
| pub(super) fn mir_assign_valid_types<'tcx>( |
| tcx: TyCtxt<'tcx>, |
| param_env: ParamEnv<'tcx>, |
| src: TyAndLayout<'tcx>, |
| dest: TyAndLayout<'tcx>, |
| ) -> bool { |
| // Type-changing assignments can happen when subtyping is used. While |
| // all normal lifetimes are erased, higher-ranked types with their |
| // late-bound lifetimes are still around and can lead to type |
| // differences. So we compare ignoring lifetimes. |
| if equal_up_to_regions(tcx, param_env, src.ty, dest.ty) { |
| // Make sure the layout is equal, too -- just to be safe. Miri really |
| // needs layout equality. For performance reason we skip this check when |
| // the types are equal. Equal types *can* have different layouts when |
| // enum downcast is involved (as enum variants carry the type of the |
| // enum), but those should never occur in assignments. |
| if cfg!(debug_assertions) || src.ty != dest.ty { |
| assert_eq!(src.layout, dest.layout); |
| } |
| true |
| } else { |
| false |
| } |
| } |
| |
| /// Use the already known layout if given (but sanity check in debug mode), |
| /// or compute the layout. |
| #[cfg_attr(not(debug_assertions), inline(always))] |
| pub(super) fn from_known_layout<'tcx>( |
| tcx: TyCtxtAt<'tcx>, |
| param_env: ParamEnv<'tcx>, |
| known_layout: Option<TyAndLayout<'tcx>>, |
| compute: impl FnOnce() -> InterpResult<'tcx, TyAndLayout<'tcx>>, |
| ) -> InterpResult<'tcx, TyAndLayout<'tcx>> { |
| match known_layout { |
| None => compute(), |
| Some(known_layout) => { |
| if cfg!(debug_assertions) { |
| let check_layout = compute()?; |
| if !mir_assign_valid_types(tcx.tcx, param_env, check_layout, known_layout) { |
| span_bug!( |
| tcx.span, |
| "expected type differs from actual type.\nexpected: {:?}\nactual: {:?}", |
| known_layout.ty, |
| check_layout.ty, |
| ); |
| } |
| } |
| Ok(known_layout) |
| } |
| } |
| } |
| |
| impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> { |
| pub fn new( |
| tcx: TyCtxt<'tcx>, |
| root_span: Span, |
| param_env: ty::ParamEnv<'tcx>, |
| machine: M, |
| memory_extra: M::MemoryExtra, |
| ) -> Self { |
| InterpCx { |
| machine, |
| tcx: tcx.at(root_span), |
| param_env, |
| memory: Memory::new(tcx, memory_extra), |
| vtables: FxHashMap::default(), |
| } |
| } |
| |
| #[inline(always)] |
| pub fn cur_span(&self) -> Span { |
| self.stack().last().map(|f| f.current_span()).unwrap_or(self.tcx.span) |
| } |
| |
| #[inline(always)] |
| pub fn force_ptr( |
| &self, |
| scalar: Scalar<M::PointerTag>, |
| ) -> InterpResult<'tcx, Pointer<M::PointerTag>> { |
| self.memory.force_ptr(scalar) |
| } |
| |
| #[inline(always)] |
| pub fn force_bits( |
| &self, |
| scalar: Scalar<M::PointerTag>, |
| size: Size, |
| ) -> InterpResult<'tcx, u128> { |
| self.memory.force_bits(scalar, size) |
| } |
| |
| /// Call this to turn untagged "global" pointers (obtained via `tcx`) into |
| /// the machine pointer to the allocation. Must never be used |
| /// for any other pointers, nor for TLS statics. |
| /// |
| /// Using the resulting pointer represents a *direct* access to that memory |
| /// (e.g. by directly using a `static`), |
| /// as opposed to access through a pointer that was created by the program. |
| /// |
| /// This function can fail only if `ptr` points to an `extern static`. |
| #[inline(always)] |
| pub fn global_base_pointer(&self, ptr: Pointer) -> InterpResult<'tcx, Pointer<M::PointerTag>> { |
| self.memory.global_base_pointer(ptr) |
| } |
| |
| #[inline(always)] |
| pub(crate) fn stack(&self) -> &[Frame<'mir, 'tcx, M::PointerTag, M::FrameExtra>] { |
| M::stack(self) |
| } |
| |
| #[inline(always)] |
| pub(crate) fn stack_mut( |
| &mut self, |
| ) -> &mut Vec<Frame<'mir, 'tcx, M::PointerTag, M::FrameExtra>> { |
| M::stack_mut(self) |
| } |
| |
| #[inline(always)] |
| pub fn frame_idx(&self) -> usize { |
| let stack = self.stack(); |
| assert!(!stack.is_empty()); |
| stack.len() - 1 |
| } |
| |
| #[inline(always)] |
| pub fn frame(&self) -> &Frame<'mir, 'tcx, M::PointerTag, M::FrameExtra> { |
| self.stack().last().expect("no call frames exist") |
| } |
| |
| #[inline(always)] |
| pub fn frame_mut(&mut self) -> &mut Frame<'mir, 'tcx, M::PointerTag, M::FrameExtra> { |
| self.stack_mut().last_mut().expect("no call frames exist") |
| } |
| |
| #[inline(always)] |
| pub(super) fn body(&self) -> &'mir mir::Body<'tcx> { |
| self.frame().body |
| } |
| |
| #[inline(always)] |
| pub fn sign_extend(&self, value: u128, ty: TyAndLayout<'_>) -> u128 { |
| assert!(ty.abi.is_signed()); |
| sign_extend(value, ty.size) |
| } |
| |
| #[inline(always)] |
| pub fn truncate(&self, value: u128, ty: TyAndLayout<'_>) -> u128 { |
| truncate(value, ty.size) |
| } |
| |
| #[inline] |
| pub fn type_is_sized(&self, ty: Ty<'tcx>) -> bool { |
| ty.is_sized(self.tcx, self.param_env) |
| } |
| |
| #[inline] |
| pub fn type_is_freeze(&self, ty: Ty<'tcx>) -> bool { |
| ty.is_freeze(self.tcx, self.param_env) |
| } |
| |
| pub fn load_mir( |
| &self, |
| instance: ty::InstanceDef<'tcx>, |
| promoted: Option<mir::Promoted>, |
| ) -> InterpResult<'tcx, &'tcx mir::Body<'tcx>> { |
| // do not continue if typeck errors occurred (can only occur in local crate) |
| let def = instance.with_opt_param(); |
| if let Some(def) = def.as_local() { |
| if self.tcx.has_typeck_results(def.did) { |
| if let Some(error_reported) = self.tcx.typeck_opt_const_arg(def).tainted_by_errors { |
| throw_inval!(TypeckError(error_reported)) |
| } |
| } |
| } |
| trace!("load mir(instance={:?}, promoted={:?})", instance, promoted); |
| if let Some(promoted) = promoted { |
| return Ok(&self.tcx.promoted_mir_opt_const_arg(def)[promoted]); |
| } |
| match instance { |
| ty::InstanceDef::Item(def) => { |
| if self.tcx.is_mir_available(def.did) { |
| Ok(self.tcx.optimized_mir_opt_const_arg(def)) |
| } else { |
| throw_unsup!(NoMirFor(def.did)) |
| } |
| } |
| _ => Ok(self.tcx.instance_mir(instance)), |
| } |
| } |
| |
| /// Call this on things you got out of the MIR (so it is as generic as the current |
| /// stack frame), to bring it into the proper environment for this interpreter. |
| pub(super) fn subst_from_current_frame_and_normalize_erasing_regions<T: TypeFoldable<'tcx>>( |
| &self, |
| value: T, |
| ) -> T { |
| self.subst_from_frame_and_normalize_erasing_regions(self.frame(), value) |
| } |
| |
| /// Call this on things you got out of the MIR (so it is as generic as the provided |
| /// stack frame), to bring it into the proper environment for this interpreter. |
| pub(super) fn subst_from_frame_and_normalize_erasing_regions<T: TypeFoldable<'tcx>>( |
| &self, |
| frame: &Frame<'mir, 'tcx, M::PointerTag, M::FrameExtra>, |
| value: T, |
| ) -> T { |
| if let Some(substs) = frame.instance.substs_for_mir_body() { |
| self.tcx.subst_and_normalize_erasing_regions(substs, self.param_env, &value) |
| } else { |
| self.tcx.normalize_erasing_regions(self.param_env, value) |
| } |
| } |
| |
| /// The `substs` are assumed to already be in our interpreter "universe" (param_env). |
| pub(super) fn resolve( |
| &self, |
| def: ty::WithOptConstParam<DefId>, |
| substs: SubstsRef<'tcx>, |
| ) -> InterpResult<'tcx, ty::Instance<'tcx>> { |
| trace!("resolve: {:?}, {:#?}", def, substs); |
| trace!("param_env: {:#?}", self.param_env); |
| trace!("substs: {:#?}", substs); |
| match ty::Instance::resolve_opt_const_arg(*self.tcx, self.param_env, def, substs) { |
| Ok(Some(instance)) => Ok(instance), |
| Ok(None) => throw_inval!(TooGeneric), |
| |
| // FIXME(eddyb) this could be a bit more specific than `TypeckError`. |
| Err(error_reported) => throw_inval!(TypeckError(error_reported)), |
| } |
| } |
| |
| pub fn layout_of_local( |
| &self, |
| frame: &Frame<'mir, 'tcx, M::PointerTag, M::FrameExtra>, |
| local: mir::Local, |
| layout: Option<TyAndLayout<'tcx>>, |
| ) -> InterpResult<'tcx, TyAndLayout<'tcx>> { |
| // `const_prop` runs into this with an invalid (empty) frame, so we |
| // have to support that case (mostly by skipping all caching). |
| match frame.locals.get(local).and_then(|state| state.layout.get()) { |
| None => { |
| let layout = from_known_layout(self.tcx, self.param_env, layout, || { |
| let local_ty = frame.body.local_decls[local].ty; |
| let local_ty = |
| self.subst_from_frame_and_normalize_erasing_regions(frame, local_ty); |
| self.layout_of(local_ty) |
| })?; |
| if let Some(state) = frame.locals.get(local) { |
| // Layouts of locals are requested a lot, so we cache them. |
| state.layout.set(Some(layout)); |
| } |
| Ok(layout) |
| } |
| Some(layout) => Ok(layout), |
| } |
| } |
| |
| /// Returns the actual dynamic size and alignment of the place at the given type. |
| /// Only the "meta" (metadata) part of the place matters. |
| /// This can fail to provide an answer for extern types. |
| pub(super) fn size_and_align_of( |
| &self, |
| metadata: MemPlaceMeta<M::PointerTag>, |
| layout: TyAndLayout<'tcx>, |
| ) -> InterpResult<'tcx, Option<(Size, Align)>> { |
| if !layout.is_unsized() { |
| return Ok(Some((layout.size, layout.align.abi))); |
| } |
| match layout.ty.kind() { |
| ty::Adt(..) | ty::Tuple(..) => { |
| // First get the size of all statically known fields. |
| // Don't use type_of::sizing_type_of because that expects t to be sized, |
| // and it also rounds up to alignment, which we want to avoid, |
| // as the unsized field's alignment could be smaller. |
| assert!(!layout.ty.is_simd()); |
| assert!(layout.fields.count() > 0); |
| trace!("DST layout: {:?}", layout); |
| |
| let sized_size = layout.fields.offset(layout.fields.count() - 1); |
| let sized_align = layout.align.abi; |
| trace!( |
| "DST {} statically sized prefix size: {:?} align: {:?}", |
| layout.ty, |
| sized_size, |
| sized_align |
| ); |
| |
| // Recurse to get the size of the dynamically sized field (must be |
| // the last field). Can't have foreign types here, how would we |
| // adjust alignment and size for them? |
| let field = layout.field(self, layout.fields.count() - 1)?; |
| let (unsized_size, unsized_align) = match self.size_and_align_of(metadata, field)? { |
| Some(size_and_align) => size_and_align, |
| None => { |
| // A field with extern type. If this field is at offset 0, we behave |
| // like the underlying extern type. |
| // FIXME: Once we have made decisions for how to handle size and alignment |
| // of `extern type`, this should be adapted. It is just a temporary hack |
| // to get some code to work that probably ought to work. |
| if sized_size == Size::ZERO { |
| return Ok(None); |
| } else { |
| span_bug!( |
| self.cur_span(), |
| "Fields cannot be extern types, unless they are at offset 0" |
| ) |
| } |
| } |
| }; |
| |
| // FIXME (#26403, #27023): We should be adding padding |
| // to `sized_size` (to accommodate the `unsized_align` |
| // required of the unsized field that follows) before |
| // summing it with `sized_size`. (Note that since #26403 |
| // is unfixed, we do not yet add the necessary padding |
| // here. But this is where the add would go.) |
| |
| // Return the sum of sizes and max of aligns. |
| let size = sized_size + unsized_size; // `Size` addition |
| |
| // Choose max of two known alignments (combined value must |
| // be aligned according to more restrictive of the two). |
| let align = sized_align.max(unsized_align); |
| |
| // Issue #27023: must add any necessary padding to `size` |
| // (to make it a multiple of `align`) before returning it. |
| let size = size.align_to(align); |
| |
| // Check if this brought us over the size limit. |
| if size.bytes() >= self.tcx.data_layout.obj_size_bound() { |
| throw_ub!(InvalidMeta("total size is bigger than largest supported object")); |
| } |
| Ok(Some((size, align))) |
| } |
| ty::Dynamic(..) => { |
| let vtable = metadata.unwrap_meta(); |
| // Read size and align from vtable (already checks size). |
| Ok(Some(self.read_size_and_align_from_vtable(vtable)?)) |
| } |
| |
| ty::Slice(_) | ty::Str => { |
| let len = metadata.unwrap_meta().to_machine_usize(self)?; |
| let elem = layout.field(self, 0)?; |
| |
| // Make sure the slice is not too big. |
| let size = elem.size.checked_mul(len, self).ok_or_else(|| { |
| err_ub!(InvalidMeta("slice is bigger than largest supported object")) |
| })?; |
| Ok(Some((size, elem.align.abi))) |
| } |
| |
| ty::Foreign(_) => Ok(None), |
| |
| _ => span_bug!(self.cur_span(), "size_and_align_of::<{:?}> not supported", layout.ty), |
| } |
| } |
| #[inline] |
| pub fn size_and_align_of_mplace( |
| &self, |
| mplace: MPlaceTy<'tcx, M::PointerTag>, |
| ) -> InterpResult<'tcx, Option<(Size, Align)>> { |
| self.size_and_align_of(mplace.meta, mplace.layout) |
| } |
| |
| pub fn push_stack_frame( |
| &mut self, |
| instance: ty::Instance<'tcx>, |
| body: &'mir mir::Body<'tcx>, |
| return_place: Option<PlaceTy<'tcx, M::PointerTag>>, |
| return_to_block: StackPopCleanup, |
| ) -> InterpResult<'tcx> { |
| // first push a stack frame so we have access to the local substs |
| let pre_frame = Frame { |
| body, |
| loc: Err(body.span), // Span used for errors caused during preamble. |
| return_to_block, |
| return_place, |
| // empty local array, we fill it in below, after we are inside the stack frame and |
| // all methods actually know about the frame |
| locals: IndexVec::new(), |
| instance, |
| tracing_span: SpanGuard::new(), |
| extra: (), |
| }; |
| let frame = M::init_frame_extra(self, pre_frame)?; |
| self.stack_mut().push(frame); |
| |
| // Make sure all the constants required by this frame evaluate successfully (post-monomorphization check). |
| for const_ in &body.required_consts { |
| let span = const_.span; |
| let const_ = |
| self.subst_from_current_frame_and_normalize_erasing_regions(const_.literal); |
| self.const_to_op(const_, None).map_err(|err| { |
| // If there was an error, set the span of the current frame to this constant. |
| // Avoiding doing this when evaluation succeeds. |
| self.frame_mut().loc = Err(span); |
| err |
| })?; |
| } |
| |
| // Locals are initially uninitialized. |
| let dummy = LocalState { value: LocalValue::Uninitialized, layout: Cell::new(None) }; |
| let mut locals = IndexVec::from_elem(dummy, &body.local_decls); |
| |
| // Now mark those locals as dead that we do not want to initialize |
| match self.tcx.def_kind(instance.def_id()) { |
| // statics and constants don't have `Storage*` statements, no need to look for them |
| // |
| // FIXME: The above is likely untrue. See |
| // <https://github.com/rust-lang/rust/pull/70004#issuecomment-602022110>. Is it |
| // okay to ignore `StorageDead`/`StorageLive` annotations during CTFE? |
| DefKind::Static | DefKind::Const | DefKind::AssocConst => {} |
| _ => { |
| // Mark locals that use `Storage*` annotations as dead on function entry. |
| let always_live = AlwaysLiveLocals::new(self.body()); |
| for local in locals.indices() { |
| if !always_live.contains(local) { |
| locals[local].value = LocalValue::Dead; |
| } |
| } |
| } |
| } |
| // done |
| self.frame_mut().locals = locals; |
| M::after_stack_push(self)?; |
| self.frame_mut().loc = Ok(mir::Location::START); |
| |
| let span = info_span!("frame", "{}", instance); |
| self.frame_mut().tracing_span.enter(span); |
| |
| Ok(()) |
| } |
| |
| /// Jump to the given block. |
| #[inline] |
| pub fn go_to_block(&mut self, target: mir::BasicBlock) { |
| self.frame_mut().loc = Ok(mir::Location { block: target, statement_index: 0 }); |
| } |
| |
| /// *Return* to the given `target` basic block. |
| /// Do *not* use for unwinding! Use `unwind_to_block` instead. |
| /// |
| /// If `target` is `None`, that indicates the function cannot return, so we raise UB. |
| pub fn return_to_block(&mut self, target: Option<mir::BasicBlock>) -> InterpResult<'tcx> { |
| if let Some(target) = target { |
| self.go_to_block(target); |
| Ok(()) |
| } else { |
| throw_ub!(Unreachable) |
| } |
| } |
| |
| /// *Unwind* to the given `target` basic block. |
| /// Do *not* use for returning! Use `return_to_block` instead. |
| /// |
| /// If `target` is `None`, that indicates the function does not need cleanup during |
| /// unwinding, and we will just keep propagating that upwards. |
| pub fn unwind_to_block(&mut self, target: Option<mir::BasicBlock>) { |
| self.frame_mut().loc = match target { |
| Some(block) => Ok(mir::Location { block, statement_index: 0 }), |
| None => Err(self.frame_mut().body.span), |
| }; |
| } |
| |
| /// Pops the current frame from the stack, deallocating the |
| /// memory for allocated locals. |
| /// |
| /// If `unwinding` is `false`, then we are performing a normal return |
| /// from a function. In this case, we jump back into the frame of the caller, |
| /// and continue execution as normal. |
| /// |
| /// If `unwinding` is `true`, then we are in the middle of a panic, |
| /// and need to unwind this frame. In this case, we jump to the |
| /// `cleanup` block for the function, which is responsible for running |
| /// `Drop` impls for any locals that have been initialized at this point. |
| /// The cleanup block ends with a special `Resume` terminator, which will |
| /// cause us to continue unwinding. |
| pub(super) fn pop_stack_frame(&mut self, unwinding: bool) -> InterpResult<'tcx> { |
| info!( |
| "popping stack frame ({})", |
| if unwinding { "during unwinding" } else { "returning from function" } |
| ); |
| |
| // Sanity check `unwinding`. |
| assert_eq!( |
| unwinding, |
| match self.frame().loc { |
| Ok(loc) => self.body().basic_blocks()[loc.block].is_cleanup, |
| Err(_) => true, |
| } |
| ); |
| |
| if unwinding && self.frame_idx() == 0 { |
| throw_ub_format!("unwinding past the topmost frame of the stack"); |
| } |
| |
| let frame = |
| self.stack_mut().pop().expect("tried to pop a stack frame, but there were none"); |
| |
| if !unwinding { |
| // Copy the return value to the caller's stack frame. |
| if let Some(return_place) = frame.return_place { |
| let op = self.access_local(&frame, mir::RETURN_PLACE, None)?; |
| self.copy_op_transmute(op, return_place)?; |
| trace!("{:?}", self.dump_place(*return_place)); |
| } else { |
| throw_ub!(Unreachable); |
| } |
| } |
| |
| // Now where do we jump next? |
| |
| // Usually we want to clean up (deallocate locals), but in a few rare cases we don't. |
| // In that case, we return early. We also avoid validation in that case, |
| // because this is CTFE and the final value will be thoroughly validated anyway. |
| let (cleanup, next_block) = match frame.return_to_block { |
| StackPopCleanup::Goto { ret, unwind } => { |
| (true, Some(if unwinding { unwind } else { ret })) |
| } |
| StackPopCleanup::None { cleanup, .. } => (cleanup, None), |
| }; |
| |
| if !cleanup { |
| assert!(self.stack().is_empty(), "only the topmost frame should ever be leaked"); |
| assert!(next_block.is_none(), "tried to skip cleanup when we have a next block!"); |
| assert!(!unwinding, "tried to skip cleanup during unwinding"); |
| // Leak the locals, skip validation, skip machine hook. |
| return Ok(()); |
| } |
| |
| // Cleanup: deallocate all locals that are backed by an allocation. |
| for local in &frame.locals { |
| self.deallocate_local(local.value)?; |
| } |
| |
| if M::after_stack_pop(self, frame, unwinding)? == StackPopJump::NoJump { |
| // The hook already did everything. |
| // We want to skip the `info!` below, hence early return. |
| return Ok(()); |
| } |
| // Normal return, figure out where to jump. |
| if unwinding { |
| // Follow the unwind edge. |
| let unwind = next_block.expect("Encountered StackPopCleanup::None when unwinding!"); |
| self.unwind_to_block(unwind); |
| } else { |
| // Follow the normal return edge. |
| if let Some(ret) = next_block { |
| self.return_to_block(ret)?; |
| } |
| } |
| |
| Ok(()) |
| } |
| |
| /// Mark a storage as live, killing the previous content and returning it. |
| /// Remember to deallocate that! |
| pub fn storage_live( |
| &mut self, |
| local: mir::Local, |
| ) -> InterpResult<'tcx, LocalValue<M::PointerTag>> { |
| assert!(local != mir::RETURN_PLACE, "Cannot make return place live"); |
| trace!("{:?} is now live", local); |
| |
| let local_val = LocalValue::Uninitialized; |
| // StorageLive *always* kills the value that's currently stored. |
| // However, we do not error if the variable already is live; |
| // see <https://github.com/rust-lang/rust/issues/42371>. |
| Ok(mem::replace(&mut self.frame_mut().locals[local].value, local_val)) |
| } |
| |
| /// Returns the old value of the local. |
| /// Remember to deallocate that! |
| pub fn storage_dead(&mut self, local: mir::Local) -> LocalValue<M::PointerTag> { |
| assert!(local != mir::RETURN_PLACE, "Cannot make return place dead"); |
| trace!("{:?} is now dead", local); |
| |
| mem::replace(&mut self.frame_mut().locals[local].value, LocalValue::Dead) |
| } |
| |
| pub(super) fn deallocate_local( |
| &mut self, |
| local: LocalValue<M::PointerTag>, |
| ) -> InterpResult<'tcx> { |
| // FIXME: should we tell the user that there was a local which was never written to? |
| if let LocalValue::Live(Operand::Indirect(MemPlace { ptr, .. })) = local { |
| // All locals have a backing allocation, even if the allocation is empty |
| // due to the local having ZST type. |
| let ptr = ptr.assert_ptr(); |
| trace!("deallocating local: {:?}", self.memory.dump_alloc(ptr.alloc_id)); |
| self.memory.deallocate_local(ptr)?; |
| }; |
| Ok(()) |
| } |
| |
| pub fn eval_to_allocation( |
| &self, |
| gid: GlobalId<'tcx>, |
| ) -> InterpResult<'tcx, MPlaceTy<'tcx, M::PointerTag>> { |
| // For statics we pick `ParamEnv::reveal_all`, because statics don't have generics |
| // and thus don't care about the parameter environment. While we could just use |
| // `self.param_env`, that would mean we invoke the query to evaluate the static |
| // with different parameter environments, thus causing the static to be evaluated |
| // multiple times. |
| let param_env = if self.tcx.is_static(gid.instance.def_id()) { |
| ty::ParamEnv::reveal_all() |
| } else { |
| self.param_env |
| }; |
| let val = self.tcx.eval_to_allocation_raw(param_env.and(gid))?; |
| self.raw_const_to_mplace(val) |
| } |
| |
| #[must_use] |
| pub fn dump_place(&'a self, place: Place<M::PointerTag>) -> PlacePrinter<'a, 'mir, 'tcx, M> { |
| PlacePrinter { ecx: self, place } |
| } |
| |
| #[must_use] |
| pub fn generate_stacktrace(&self) -> Vec<FrameInfo<'tcx>> { |
| let mut frames = Vec::new(); |
| for frame in self.stack().iter().rev() { |
| let lint_root = frame.current_source_info().and_then(|source_info| { |
| match &frame.body.source_scopes[source_info.scope].local_data { |
| mir::ClearCrossCrate::Set(data) => Some(data.lint_root), |
| mir::ClearCrossCrate::Clear => None, |
| } |
| }); |
| let span = frame.current_span(); |
| |
| frames.push(FrameInfo { span, instance: frame.instance, lint_root }); |
| } |
| trace!("generate stacktrace: {:#?}", frames); |
| frames |
| } |
| } |
| |
| #[doc(hidden)] |
| /// Helper struct for the `dump_place` function. |
| pub struct PlacePrinter<'a, 'mir, 'tcx, M: Machine<'mir, 'tcx>> { |
| ecx: &'a InterpCx<'mir, 'tcx, M>, |
| place: Place<M::PointerTag>, |
| } |
| |
| impl<'a, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> std::fmt::Debug |
| for PlacePrinter<'a, 'mir, 'tcx, M> |
| { |
| fn fmt(&self, fmt: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { |
| match self.place { |
| Place::Local { frame, local } => { |
| let mut allocs = Vec::new(); |
| write!(fmt, "{:?}", local)?; |
| if frame != self.ecx.frame_idx() { |
| write!(fmt, " ({} frames up)", self.ecx.frame_idx() - frame)?; |
| } |
| write!(fmt, ":")?; |
| |
| match self.ecx.stack()[frame].locals[local].value { |
| LocalValue::Dead => write!(fmt, " is dead")?, |
| LocalValue::Uninitialized => write!(fmt, " is uninitialized")?, |
| LocalValue::Live(Operand::Indirect(mplace)) => match mplace.ptr { |
| Scalar::Ptr(ptr) => { |
| write!( |
| fmt, |
| " by align({}){} ref:", |
| mplace.align.bytes(), |
| match mplace.meta { |
| MemPlaceMeta::Meta(meta) => format!(" meta({:?})", meta), |
| MemPlaceMeta::Poison | MemPlaceMeta::None => String::new(), |
| } |
| )?; |
| allocs.push(ptr.alloc_id); |
| } |
| ptr => write!(fmt, " by integral ref: {:?}", ptr)?, |
| }, |
| LocalValue::Live(Operand::Immediate(Immediate::Scalar(val))) => { |
| write!(fmt, " {:?}", val)?; |
| if let ScalarMaybeUninit::Scalar(Scalar::Ptr(ptr)) = val { |
| allocs.push(ptr.alloc_id); |
| } |
| } |
| LocalValue::Live(Operand::Immediate(Immediate::ScalarPair(val1, val2))) => { |
| write!(fmt, " ({:?}, {:?})", val1, val2)?; |
| if let ScalarMaybeUninit::Scalar(Scalar::Ptr(ptr)) = val1 { |
| allocs.push(ptr.alloc_id); |
| } |
| if let ScalarMaybeUninit::Scalar(Scalar::Ptr(ptr)) = val2 { |
| allocs.push(ptr.alloc_id); |
| } |
| } |
| } |
| |
| write!(fmt, ": {:?}", self.ecx.memory.dump_allocs(allocs)) |
| } |
| Place::Ptr(mplace) => match mplace.ptr { |
| Scalar::Ptr(ptr) => write!( |
| fmt, |
| "by align({}) ref: {:?}", |
| mplace.align.bytes(), |
| self.ecx.memory.dump_alloc(ptr.alloc_id) |
| ), |
| ptr => write!(fmt, " integral by ref: {:?}", ptr), |
| }, |
| } |
| } |
| } |
| |
| impl<'ctx, 'mir, 'tcx, Tag, Extra> HashStable<StableHashingContext<'ctx>> |
| for Frame<'mir, 'tcx, Tag, Extra> |
| where |
| Extra: HashStable<StableHashingContext<'ctx>>, |
| Tag: HashStable<StableHashingContext<'ctx>>, |
| { |
| fn hash_stable(&self, hcx: &mut StableHashingContext<'ctx>, hasher: &mut StableHasher) { |
| // Exhaustive match on fields to make sure we forget no field. |
| let Frame { |
| body, |
| instance, |
| return_to_block, |
| return_place, |
| locals, |
| loc, |
| extra, |
| tracing_span: _, |
| } = self; |
| body.hash_stable(hcx, hasher); |
| instance.hash_stable(hcx, hasher); |
| return_to_block.hash_stable(hcx, hasher); |
| return_place.as_ref().map(|r| &**r).hash_stable(hcx, hasher); |
| locals.hash_stable(hcx, hasher); |
| loc.hash_stable(hcx, hasher); |
| extra.hash_stable(hcx, hasher); |
| } |
| } |
