5 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
6 use rustc_hir::{self as hir, def_id::DefId, definitions::DefPathData};
7 use rustc_index::vec::IndexVec;
8 use rustc_macros::HashStable;
10 use rustc_middle::mir::interpret::{InterpError, InvalidProgramInfo};
11 use rustc_middle::ty::layout::{
12 self, FnAbiError, FnAbiOfHelpers, FnAbiRequest, LayoutError, LayoutOf, LayoutOfHelpers,
15 use rustc_middle::ty::{
16 self, query::TyCtxtAt, subst::SubstsRef, ParamEnv, Ty, TyCtxt, TypeFoldable,
18 use rustc_mir_dataflow::storage::AlwaysLiveLocals;
19 use rustc_query_system::ich::StableHashingContext;
20 use rustc_session::Limit;
21 use rustc_span::{Pos, Span};
22 use rustc_target::abi::{call::FnAbi, Align, HasDataLayout, Size, TargetDataLayout};
25 AllocId, GlobalId, Immediate, InterpErrorInfo, InterpResult, MPlaceTy, Machine, MemPlace,
26 MemPlaceMeta, Memory, MemoryKind, Operand, Place, PlaceTy, Pointer, Provenance, Scalar,
27 ScalarMaybeUninit, StackPopJump,
29 use crate::transform::validate::equal_up_to_regions;
31 pub struct InterpCx<'mir, 'tcx, M: Machine<'mir, 'tcx>> {
32 /// Stores the `Machine` instance.
34 /// Note: the stack is provided by the machine.
37 /// The results of the type checker, from rustc.
38 /// The span in this is the "root" of the evaluation, i.e., the const
39 /// we are evaluating (if this is CTFE).
40 pub tcx: TyCtxtAt<'tcx>,
42 /// Bounds in scope for polymorphic evaluations.
43 pub(crate) param_env: ty::ParamEnv<'tcx>,
45 /// The virtual memory system.
46 pub memory: Memory<'mir, 'tcx, M>,
48 /// The recursion limit (cached from `tcx.recursion_limit(())`)
49 pub recursion_limit: Limit,
52 // The Phantomdata exists to prevent this type from being `Send`. If it were sent across a thread
53 // boundary and dropped in the other thread, it would exit the span in the other thread.
54 struct SpanGuard(tracing::Span, std::marker::PhantomData<*const u8>);
57 /// By default a `SpanGuard` does nothing.
59 Self(tracing::Span::none(), std::marker::PhantomData)
62 /// If a span is entered, we exit the previous span (if any, normally none) and enter the
63 /// new span. This is mainly so we don't have to use `Option` for the `tracing_span` field of
64 /// `Frame` by creating a dummy span to being with and then entering it once the frame has
66 fn enter(&mut self, span: tracing::Span) {
67 // This executes the destructor on the previous instance of `SpanGuard`, ensuring that
68 // we never enter or exit more spans than vice versa. Unless you `mem::leak`, then we
69 // can't protect the tracing stack, but that'll just lead to weird logging, no actual
71 *self = Self(span, std::marker::PhantomData);
72 self.0.with_subscriber(|(id, dispatch)| {
78 impl Drop for SpanGuard {
80 self.0.with_subscriber(|(id, dispatch)| {
87 pub struct Frame<'mir, 'tcx, Tag: Provenance = AllocId, Extra = ()> {
88 ////////////////////////////////////////////////////////////////////////////////
89 // Function and callsite information
90 ////////////////////////////////////////////////////////////////////////////////
91 /// The MIR for the function called on this frame.
92 pub body: &'mir mir::Body<'tcx>,
94 /// The def_id and substs of the current function.
95 pub instance: ty::Instance<'tcx>,
97 /// Extra data for the machine.
100 ////////////////////////////////////////////////////////////////////////////////
101 // Return place and locals
102 ////////////////////////////////////////////////////////////////////////////////
103 /// Work to perform when returning from this function.
104 pub return_to_block: StackPopCleanup,
106 /// The location where the result of the current stack frame should be written to,
107 /// and its layout in the caller.
108 pub return_place: Option<PlaceTy<'tcx, Tag>>,
110 /// The list of locals for this stack frame, stored in order as
111 /// `[return_ptr, arguments..., variables..., temporaries...]`.
112 /// The locals are stored as `Option<Value>`s.
113 /// `None` represents a local that is currently dead, while a live local
114 /// can either directly contain `Scalar` or refer to some part of an `Allocation`.
115 pub locals: IndexVec<mir::Local, LocalState<'tcx, Tag>>,
117 /// The span of the `tracing` crate is stored here.
118 /// When the guard is dropped, the span is exited. This gives us
119 /// a full stack trace on all tracing statements.
120 tracing_span: SpanGuard,
122 ////////////////////////////////////////////////////////////////////////////////
123 // Current position within the function
124 ////////////////////////////////////////////////////////////////////////////////
125 /// If this is `Err`, we are not currently executing any particular statement in
126 /// this frame (can happen e.g. during frame initialization, and during unwinding on
127 /// frames without cleanup code).
128 /// We basically abuse `Result` as `Either`.
129 pub(super) loc: Result<mir::Location, Span>,
132 /// What we store about a frame in an interpreter backtrace.
134 pub struct FrameInfo<'tcx> {
135 pub instance: ty::Instance<'tcx>,
137 pub lint_root: Option<hir::HirId>,
140 /// Unwind information.
141 #[derive(Clone, Copy, Eq, PartialEq, Debug, HashStable)]
142 pub enum StackPopUnwind {
143 /// The cleanup block.
144 Cleanup(mir::BasicBlock),
145 /// No cleanup needs to be done.
147 /// Unwinding is not allowed (UB).
151 #[derive(Clone, Copy, Eq, PartialEq, Debug, HashStable)] // Miri debug-prints these
152 pub enum StackPopCleanup {
153 /// Jump to the next block in the caller, or cause UB if None (that's a function
154 /// that may never return). Also store layout of return place so
155 /// we can validate it at that layout.
156 /// `ret` stores the block we jump to on a normal return, while `unwind`
157 /// stores the block used for cleanup during unwinding.
158 Goto { ret: Option<mir::BasicBlock>, unwind: StackPopUnwind },
159 /// Just do nothing: Used by Main and for the `box_alloc` hook in miri.
160 /// `cleanup` says whether locals are deallocated. Static computation
161 /// wants them leaked to intern what they need (and just throw away
162 /// the entire `ecx` when it is done).
163 None { cleanup: bool },
166 /// State of a local variable including a memoized layout
167 #[derive(Clone, PartialEq, Eq, HashStable)]
168 pub struct LocalState<'tcx, Tag: Provenance = AllocId> {
169 pub value: LocalValue<Tag>,
170 /// Don't modify if `Some`, this is only used to prevent computing the layout twice
171 #[stable_hasher(ignore)]
172 pub layout: Cell<Option<TyAndLayout<'tcx>>>,
175 /// Current value of a local variable
176 #[derive(Copy, Clone, PartialEq, Eq, HashStable, Debug)] // Miri debug-prints these
177 pub enum LocalValue<Tag: Provenance = AllocId> {
178 /// This local is not currently alive, and cannot be used at all.
180 /// This local is alive but not yet initialized. It can be written to
181 /// but not read from or its address taken. Locals get initialized on
182 /// first write because for unsized locals, we do not know their size
185 /// A normal, live local.
186 /// Mostly for convenience, we re-use the `Operand` type here.
187 /// This is an optimization over just always having a pointer here;
188 /// we can thus avoid doing an allocation when the local just stores
189 /// immediate values *and* never has its address taken.
193 impl<'tcx, Tag: Provenance + 'static> LocalState<'tcx, Tag> {
194 /// Read the local's value or error if the local is not yet live or not live anymore.
196 /// Note: This may only be invoked from the `Machine::access_local` hook and not from
197 /// anywhere else. You may be invalidating machine invariants if you do!
198 pub fn access(&self) -> InterpResult<'tcx, Operand<Tag>> {
200 LocalValue::Dead => throw_ub!(DeadLocal),
201 LocalValue::Uninitialized => {
202 bug!("The type checker should prevent reading from a never-written local")
204 LocalValue::Live(val) => Ok(val),
208 /// Overwrite the local. If the local can be overwritten in place, return a reference
209 /// to do so; otherwise return the `MemPlace` to consult instead.
211 /// Note: This may only be invoked from the `Machine::access_local_mut` hook and not from
212 /// anywhere else. You may be invalidating machine invariants if you do!
215 ) -> InterpResult<'tcx, Result<&mut LocalValue<Tag>, MemPlace<Tag>>> {
217 LocalValue::Dead => throw_ub!(DeadLocal),
218 LocalValue::Live(Operand::Indirect(mplace)) => Ok(Err(mplace)),
220 local @ (LocalValue::Live(Operand::Immediate(_)) | LocalValue::Uninitialized) => {
227 impl<'mir, 'tcx, Tag: Provenance> Frame<'mir, 'tcx, Tag> {
228 pub fn with_extra<Extra>(self, extra: Extra) -> Frame<'mir, 'tcx, Tag, Extra> {
231 instance: self.instance,
232 return_to_block: self.return_to_block,
233 return_place: self.return_place,
237 tracing_span: self.tracing_span,
242 impl<'mir, 'tcx, Tag: Provenance, Extra> Frame<'mir, 'tcx, Tag, Extra> {
243 /// Get the current location within the Frame.
245 /// If this is `Err`, we are not currently executing any particular statement in
246 /// this frame (can happen e.g. during frame initialization, and during unwinding on
247 /// frames without cleanup code).
248 /// We basically abuse `Result` as `Either`.
251 pub fn current_loc(&self) -> Result<mir::Location, Span> {
255 /// Return the `SourceInfo` of the current instruction.
256 pub fn current_source_info(&self) -> Option<&mir::SourceInfo> {
257 self.loc.ok().map(|loc| self.body.source_info(loc))
260 pub fn current_span(&self) -> Span {
262 Ok(loc) => self.body.source_info(loc).span,
268 impl<'tcx> fmt::Display for FrameInfo<'tcx> {
269 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
270 ty::tls::with(|tcx| {
271 if tcx.def_key(self.instance.def_id()).disambiguated_data.data
272 == DefPathData::ClosureExpr
274 write!(f, "inside closure")?;
276 write!(f, "inside `{}`", self.instance)?;
278 if !self.span.is_dummy() {
279 let sm = tcx.sess.source_map();
280 let lo = sm.lookup_char_pos(self.span.lo());
284 sm.filename_for_diagnostics(&lo.file.name),
286 lo.col.to_usize() + 1
294 impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> HasDataLayout for InterpCx<'mir, 'tcx, M> {
296 fn data_layout(&self) -> &TargetDataLayout {
297 &self.tcx.data_layout
301 impl<'mir, 'tcx, M> layout::HasTyCtxt<'tcx> for InterpCx<'mir, 'tcx, M>
303 M: Machine<'mir, 'tcx>,
306 fn tcx(&self) -> TyCtxt<'tcx> {
311 impl<'mir, 'tcx, M> layout::HasParamEnv<'tcx> for InterpCx<'mir, 'tcx, M>
313 M: Machine<'mir, 'tcx>,
315 fn param_env(&self) -> ty::ParamEnv<'tcx> {
320 impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> LayoutOfHelpers<'tcx> for InterpCx<'mir, 'tcx, M> {
321 type LayoutOfResult = InterpResult<'tcx, TyAndLayout<'tcx>>;
324 fn layout_tcx_at_span(&self) -> Span {
329 fn handle_layout_err(
331 err: LayoutError<'tcx>,
334 ) -> InterpErrorInfo<'tcx> {
335 err_inval!(Layout(err)).into()
339 impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> FnAbiOfHelpers<'tcx> for InterpCx<'mir, 'tcx, M> {
340 type FnAbiOfResult = InterpResult<'tcx, &'tcx FnAbi<'tcx, Ty<'tcx>>>;
342 fn handle_fn_abi_err(
344 err: FnAbiError<'tcx>,
346 _fn_abi_request: FnAbiRequest<'tcx>,
347 ) -> InterpErrorInfo<'tcx> {
349 FnAbiError::Layout(err) => err_inval!(Layout(err)).into(),
350 FnAbiError::AdjustForForeignAbi(err) => {
351 err_inval!(FnAbiAdjustForForeignAbi(err)).into()
357 /// Test if it is valid for a MIR assignment to assign `src`-typed place to `dest`-typed value.
358 /// This test should be symmetric, as it is primarily about layout compatibility.
359 pub(super) fn mir_assign_valid_types<'tcx>(
361 param_env: ParamEnv<'tcx>,
362 src: TyAndLayout<'tcx>,
363 dest: TyAndLayout<'tcx>,
365 // Type-changing assignments can happen when subtyping is used. While
366 // all normal lifetimes are erased, higher-ranked types with their
367 // late-bound lifetimes are still around and can lead to type
368 // differences. So we compare ignoring lifetimes.
369 if equal_up_to_regions(tcx, param_env, src.ty, dest.ty) {
370 // Make sure the layout is equal, too -- just to be safe. Miri really
371 // needs layout equality. For performance reason we skip this check when
372 // the types are equal. Equal types *can* have different layouts when
373 // enum downcast is involved (as enum variants carry the type of the
374 // enum), but those should never occur in assignments.
375 if cfg!(debug_assertions) || src.ty != dest.ty {
376 assert_eq!(src.layout, dest.layout);
384 /// Use the already known layout if given (but sanity check in debug mode),
385 /// or compute the layout.
386 #[cfg_attr(not(debug_assertions), inline(always))]
387 pub(super) fn from_known_layout<'tcx>(
389 param_env: ParamEnv<'tcx>,
390 known_layout: Option<TyAndLayout<'tcx>>,
391 compute: impl FnOnce() -> InterpResult<'tcx, TyAndLayout<'tcx>>,
392 ) -> InterpResult<'tcx, TyAndLayout<'tcx>> {
395 Some(known_layout) => {
396 if cfg!(debug_assertions) {
397 let check_layout = compute()?;
398 if !mir_assign_valid_types(tcx.tcx, param_env, check_layout, known_layout) {
401 "expected type differs from actual type.\nexpected: {:?}\nactual: {:?}",
412 impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
416 param_env: ty::ParamEnv<'tcx>,
418 memory_extra: M::MemoryExtra,
422 tcx: tcx.at(root_span),
424 memory: Memory::new(tcx, memory_extra),
425 recursion_limit: tcx.recursion_limit(),
430 pub fn cur_span(&self) -> Span {
434 .find(|frame| !frame.instance.def.requires_caller_location(*self.tcx))
435 .map_or(self.tcx.span, |f| f.current_span())
439 pub fn scalar_to_ptr(&self, scalar: Scalar<M::PointerTag>) -> Pointer<Option<M::PointerTag>> {
440 self.memory.scalar_to_ptr(scalar)
443 /// Call this to turn untagged "global" pointers (obtained via `tcx`) into
444 /// the machine pointer to the allocation. Must never be used
445 /// for any other pointers, nor for TLS statics.
447 /// Using the resulting pointer represents a *direct* access to that memory
448 /// (e.g. by directly using a `static`),
449 /// as opposed to access through a pointer that was created by the program.
451 /// This function can fail only if `ptr` points to an `extern static`.
453 pub fn global_base_pointer(&self, ptr: Pointer) -> InterpResult<'tcx, Pointer<M::PointerTag>> {
454 self.memory.global_base_pointer(ptr)
458 pub(crate) fn stack(&self) -> &[Frame<'mir, 'tcx, M::PointerTag, M::FrameExtra>] {
463 pub(crate) fn stack_mut(
465 ) -> &mut Vec<Frame<'mir, 'tcx, M::PointerTag, M::FrameExtra>> {
470 pub fn frame_idx(&self) -> usize {
471 let stack = self.stack();
472 assert!(!stack.is_empty());
477 pub fn frame(&self) -> &Frame<'mir, 'tcx, M::PointerTag, M::FrameExtra> {
478 self.stack().last().expect("no call frames exist")
482 pub fn frame_mut(&mut self) -> &mut Frame<'mir, 'tcx, M::PointerTag, M::FrameExtra> {
483 self.stack_mut().last_mut().expect("no call frames exist")
487 pub(super) fn body(&self) -> &'mir mir::Body<'tcx> {
492 pub fn sign_extend(&self, value: u128, ty: TyAndLayout<'_>) -> u128 {
493 assert!(ty.abi.is_signed());
494 ty.size.sign_extend(value)
498 pub fn truncate(&self, value: u128, ty: TyAndLayout<'_>) -> u128 {
499 ty.size.truncate(value)
503 pub fn type_is_freeze(&self, ty: Ty<'tcx>) -> bool {
504 ty.is_freeze(self.tcx, self.param_env)
509 instance: ty::InstanceDef<'tcx>,
510 promoted: Option<mir::Promoted>,
511 ) -> InterpResult<'tcx, &'tcx mir::Body<'tcx>> {
512 // do not continue if typeck errors occurred (can only occur in local crate)
513 let def = instance.with_opt_param();
514 if let Some(def) = def.as_local() {
515 if self.tcx.has_typeck_results(def.did) {
516 if let Some(error_reported) = self.tcx.typeck_opt_const_arg(def).tainted_by_errors {
517 throw_inval!(AlreadyReported(error_reported))
521 trace!("load mir(instance={:?}, promoted={:?})", instance, promoted);
522 if let Some(promoted) = promoted {
523 return Ok(&self.tcx.promoted_mir_opt_const_arg(def)[promoted]);
525 M::load_mir(self, instance)
528 /// Call this on things you got out of the MIR (so it is as generic as the current
529 /// stack frame), to bring it into the proper environment for this interpreter.
530 pub(super) fn subst_from_current_frame_and_normalize_erasing_regions<T: TypeFoldable<'tcx>>(
533 ) -> Result<T, InterpError<'tcx>> {
534 self.subst_from_frame_and_normalize_erasing_regions(self.frame(), value)
537 /// Call this on things you got out of the MIR (so it is as generic as the provided
538 /// stack frame), to bring it into the proper environment for this interpreter.
539 pub(super) fn subst_from_frame_and_normalize_erasing_regions<T: TypeFoldable<'tcx>>(
541 frame: &Frame<'mir, 'tcx, M::PointerTag, M::FrameExtra>,
543 ) -> Result<T, InterpError<'tcx>> {
546 .try_subst_mir_and_normalize_erasing_regions(*self.tcx, self.param_env, value)
548 self.tcx.sess.delay_span_bug(
550 format!("failed to normalize {}", e.get_type_for_failure()).as_str(),
553 Err(InterpError::InvalidProgram(InvalidProgramInfo::TooGeneric))
557 /// The `substs` are assumed to already be in our interpreter "universe" (param_env).
558 pub(super) fn resolve(
560 def: ty::WithOptConstParam<DefId>,
561 substs: SubstsRef<'tcx>,
562 ) -> InterpResult<'tcx, ty::Instance<'tcx>> {
563 trace!("resolve: {:?}, {:#?}", def, substs);
564 trace!("param_env: {:#?}", self.param_env);
565 trace!("substs: {:#?}", substs);
566 match ty::Instance::resolve_opt_const_arg(*self.tcx, self.param_env, def, substs) {
567 Ok(Some(instance)) => Ok(instance),
568 Ok(None) => throw_inval!(TooGeneric),
570 // FIXME(eddyb) this could be a bit more specific than `AlreadyReported`.
571 Err(error_reported) => throw_inval!(AlreadyReported(error_reported)),
576 pub fn layout_of_local(
578 frame: &Frame<'mir, 'tcx, M::PointerTag, M::FrameExtra>,
580 layout: Option<TyAndLayout<'tcx>>,
581 ) -> InterpResult<'tcx, TyAndLayout<'tcx>> {
582 // `const_prop` runs into this with an invalid (empty) frame, so we
583 // have to support that case (mostly by skipping all caching).
584 match frame.locals.get(local).and_then(|state| state.layout.get()) {
586 let layout = from_known_layout(self.tcx, self.param_env, layout, || {
587 let local_ty = frame.body.local_decls[local].ty;
589 self.subst_from_frame_and_normalize_erasing_regions(frame, local_ty)?;
590 self.layout_of(local_ty)
592 if let Some(state) = frame.locals.get(local) {
593 // Layouts of locals are requested a lot, so we cache them.
594 state.layout.set(Some(layout));
598 Some(layout) => Ok(layout),
602 /// Returns the actual dynamic size and alignment of the place at the given type.
603 /// Only the "meta" (metadata) part of the place matters.
604 /// This can fail to provide an answer for extern types.
605 pub(super) fn size_and_align_of(
607 metadata: &MemPlaceMeta<M::PointerTag>,
608 layout: &TyAndLayout<'tcx>,
609 ) -> InterpResult<'tcx, Option<(Size, Align)>> {
610 if !layout.is_unsized() {
611 return Ok(Some((layout.size, layout.align.abi)));
613 match layout.ty.kind() {
614 ty::Adt(..) | ty::Tuple(..) => {
615 // First get the size of all statically known fields.
616 // Don't use type_of::sizing_type_of because that expects t to be sized,
617 // and it also rounds up to alignment, which we want to avoid,
618 // as the unsized field's alignment could be smaller.
619 assert!(!layout.ty.is_simd());
620 assert!(layout.fields.count() > 0);
621 trace!("DST layout: {:?}", layout);
623 let sized_size = layout.fields.offset(layout.fields.count() - 1);
624 let sized_align = layout.align.abi;
626 "DST {} statically sized prefix size: {:?} align: {:?}",
632 // Recurse to get the size of the dynamically sized field (must be
633 // the last field). Can't have foreign types here, how would we
634 // adjust alignment and size for them?
635 let field = layout.field(self, layout.fields.count() - 1);
636 let (unsized_size, unsized_align) =
637 match self.size_and_align_of(metadata, &field)? {
638 Some(size_and_align) => size_and_align,
640 // A field with an extern type. We don't know the actual dynamic size
646 // FIXME (#26403, #27023): We should be adding padding
647 // to `sized_size` (to accommodate the `unsized_align`
648 // required of the unsized field that follows) before
649 // summing it with `sized_size`. (Note that since #26403
650 // is unfixed, we do not yet add the necessary padding
651 // here. But this is where the add would go.)
653 // Return the sum of sizes and max of aligns.
654 let size = sized_size + unsized_size; // `Size` addition
656 // Choose max of two known alignments (combined value must
657 // be aligned according to more restrictive of the two).
658 let align = sized_align.max(unsized_align);
660 // Issue #27023: must add any necessary padding to `size`
661 // (to make it a multiple of `align`) before returning it.
662 let size = size.align_to(align);
664 // Check if this brought us over the size limit.
665 if size.bytes() >= self.tcx.data_layout.obj_size_bound() {
666 throw_ub!(InvalidMeta("total size is bigger than largest supported object"));
668 Ok(Some((size, align)))
671 let vtable = self.scalar_to_ptr(metadata.unwrap_meta());
672 // Read size and align from vtable (already checks size).
673 Ok(Some(self.read_size_and_align_from_vtable(vtable)?))
676 ty::Slice(_) | ty::Str => {
677 let len = metadata.unwrap_meta().to_machine_usize(self)?;
678 let elem = layout.field(self, 0);
680 // Make sure the slice is not too big.
681 let size = elem.size.checked_mul(len, self).ok_or_else(|| {
682 err_ub!(InvalidMeta("slice is bigger than largest supported object"))
684 Ok(Some((size, elem.align.abi)))
687 ty::Foreign(_) => Ok(None),
689 _ => span_bug!(self.cur_span(), "size_and_align_of::<{:?}> not supported", layout.ty),
693 pub fn size_and_align_of_mplace(
695 mplace: &MPlaceTy<'tcx, M::PointerTag>,
696 ) -> InterpResult<'tcx, Option<(Size, Align)>> {
697 self.size_and_align_of(&mplace.meta, &mplace.layout)
700 pub fn push_stack_frame(
702 instance: ty::Instance<'tcx>,
703 body: &'mir mir::Body<'tcx>,
704 return_place: Option<&PlaceTy<'tcx, M::PointerTag>>,
705 return_to_block: StackPopCleanup,
706 ) -> InterpResult<'tcx> {
707 // first push a stack frame so we have access to the local substs
708 let pre_frame = Frame {
710 loc: Err(body.span), // Span used for errors caused during preamble.
712 return_place: return_place.copied(),
713 // empty local array, we fill it in below, after we are inside the stack frame and
714 // all methods actually know about the frame
715 locals: IndexVec::new(),
717 tracing_span: SpanGuard::new(),
720 let frame = M::init_frame_extra(self, pre_frame)?;
721 self.stack_mut().push(frame);
723 // Make sure all the constants required by this frame evaluate successfully (post-monomorphization check).
724 for const_ in &body.required_consts {
725 let span = const_.span;
727 self.subst_from_current_frame_and_normalize_erasing_regions(const_.literal)?;
728 self.mir_const_to_op(&const_, None).map_err(|err| {
729 // If there was an error, set the span of the current frame to this constant.
730 // Avoiding doing this when evaluation succeeds.
731 self.frame_mut().loc = Err(span);
736 // Locals are initially uninitialized.
737 let dummy = LocalState { value: LocalValue::Uninitialized, layout: Cell::new(None) };
738 let mut locals = IndexVec::from_elem(dummy, &body.local_decls);
740 // Now mark those locals as dead that we do not want to initialize
741 // Mark locals that use `Storage*` annotations as dead on function entry.
742 let always_live = AlwaysLiveLocals::new(self.body());
743 for local in locals.indices() {
744 if !always_live.contains(local) {
745 locals[local].value = LocalValue::Dead;
749 self.frame_mut().locals = locals;
750 M::after_stack_push(self)?;
751 self.frame_mut().loc = Ok(mir::Location::START);
753 let span = info_span!("frame", "{}", instance);
754 self.frame_mut().tracing_span.enter(span);
759 /// Jump to the given block.
761 pub fn go_to_block(&mut self, target: mir::BasicBlock) {
762 self.frame_mut().loc = Ok(mir::Location { block: target, statement_index: 0 });
765 /// *Return* to the given `target` basic block.
766 /// Do *not* use for unwinding! Use `unwind_to_block` instead.
768 /// If `target` is `None`, that indicates the function cannot return, so we raise UB.
769 pub fn return_to_block(&mut self, target: Option<mir::BasicBlock>) -> InterpResult<'tcx> {
770 if let Some(target) = target {
771 self.go_to_block(target);
774 throw_ub!(Unreachable)
778 /// *Unwind* to the given `target` basic block.
779 /// Do *not* use for returning! Use `return_to_block` instead.
781 /// If `target` is `StackPopUnwind::Skip`, that indicates the function does not need cleanup
782 /// during unwinding, and we will just keep propagating that upwards.
784 /// If `target` is `StackPopUnwind::NotAllowed`, that indicates the function does not allow
785 /// unwinding, and doing so is UB.
786 pub fn unwind_to_block(&mut self, target: StackPopUnwind) -> InterpResult<'tcx> {
787 self.frame_mut().loc = match target {
788 StackPopUnwind::Cleanup(block) => Ok(mir::Location { block, statement_index: 0 }),
789 StackPopUnwind::Skip => Err(self.frame_mut().body.span),
790 StackPopUnwind::NotAllowed => {
791 throw_ub_format!("unwinding past a stack frame that does not allow unwinding")
797 /// Pops the current frame from the stack, deallocating the
798 /// memory for allocated locals.
800 /// If `unwinding` is `false`, then we are performing a normal return
801 /// from a function. In this case, we jump back into the frame of the caller,
802 /// and continue execution as normal.
804 /// If `unwinding` is `true`, then we are in the middle of a panic,
805 /// and need to unwind this frame. In this case, we jump to the
806 /// `cleanup` block for the function, which is responsible for running
807 /// `Drop` impls for any locals that have been initialized at this point.
808 /// The cleanup block ends with a special `Resume` terminator, which will
809 /// cause us to continue unwinding.
810 pub(super) fn pop_stack_frame(&mut self, unwinding: bool) -> InterpResult<'tcx> {
812 "popping stack frame ({})",
813 if unwinding { "during unwinding" } else { "returning from function" }
816 // Sanity check `unwinding`.
819 match self.frame().loc {
820 Ok(loc) => self.body().basic_blocks()[loc.block].is_cleanup,
825 if unwinding && self.frame_idx() == 0 {
826 throw_ub_format!("unwinding past the topmost frame of the stack");
830 self.stack_mut().pop().expect("tried to pop a stack frame, but there were none");
833 // Copy the return value to the caller's stack frame.
834 if let Some(ref return_place) = frame.return_place {
835 let op = self.access_local(&frame, mir::RETURN_PLACE, None)?;
836 self.copy_op_transmute(&op, return_place)?;
837 trace!("{:?}", self.dump_place(**return_place));
839 throw_ub!(Unreachable);
843 let return_to_block = frame.return_to_block;
845 // Now where do we jump next?
847 // Usually we want to clean up (deallocate locals), but in a few rare cases we don't.
848 // In that case, we return early. We also avoid validation in that case,
849 // because this is CTFE and the final value will be thoroughly validated anyway.
850 let cleanup = match return_to_block {
851 StackPopCleanup::Goto { .. } => true,
852 StackPopCleanup::None { cleanup, .. } => cleanup,
856 assert!(self.stack().is_empty(), "only the topmost frame should ever be leaked");
857 assert!(!unwinding, "tried to skip cleanup during unwinding");
858 // Leak the locals, skip validation, skip machine hook.
862 // Cleanup: deallocate all locals that are backed by an allocation.
863 for local in &frame.locals {
864 self.deallocate_local(local.value)?;
867 if M::after_stack_pop(self, frame, unwinding)? == StackPopJump::NoJump {
868 // The hook already did everything.
869 // We want to skip the `info!` below, hence early return.
872 // Normal return, figure out where to jump.
874 // Follow the unwind edge.
875 let unwind = match return_to_block {
876 StackPopCleanup::Goto { unwind, .. } => unwind,
877 StackPopCleanup::None { .. } => {
878 panic!("Encountered StackPopCleanup::None when unwinding!")
881 self.unwind_to_block(unwind)
883 // Follow the normal return edge.
884 match return_to_block {
885 StackPopCleanup::Goto { ret, .. } => self.return_to_block(ret),
886 StackPopCleanup::None { .. } => Ok(()),
891 /// Mark a storage as live, killing the previous content.
892 pub fn storage_live(&mut self, local: mir::Local) -> InterpResult<'tcx> {
893 assert!(local != mir::RETURN_PLACE, "Cannot make return place live");
894 trace!("{:?} is now live", local);
896 let local_val = LocalValue::Uninitialized;
897 // StorageLive expects the local to be dead, and marks it live.
898 let old = mem::replace(&mut self.frame_mut().locals[local].value, local_val);
899 if !matches!(old, LocalValue::Dead) {
900 throw_ub_format!("StorageLive on a local that was already live");
905 pub fn storage_dead(&mut self, local: mir::Local) -> InterpResult<'tcx> {
906 assert!(local != mir::RETURN_PLACE, "Cannot make return place dead");
907 trace!("{:?} is now dead", local);
909 // It is entirely okay for this local to be already dead (at least that's how we currently generate MIR)
910 let old = mem::replace(&mut self.frame_mut().locals[local].value, LocalValue::Dead);
911 self.deallocate_local(old)?;
915 fn deallocate_local(&mut self, local: LocalValue<M::PointerTag>) -> InterpResult<'tcx> {
916 if let LocalValue::Live(Operand::Indirect(MemPlace { ptr, .. })) = local {
917 // All locals have a backing allocation, even if the allocation is empty
918 // due to the local having ZST type. Hence we can `unwrap`.
920 "deallocating local {:?}: {:?}",
922 self.memory.dump_alloc(ptr.provenance.unwrap().get_alloc_id())
924 self.memory.deallocate(ptr, None, MemoryKind::Stack)?;
929 pub fn eval_to_allocation(
932 ) -> InterpResult<'tcx, MPlaceTy<'tcx, M::PointerTag>> {
933 // For statics we pick `ParamEnv::reveal_all`, because statics don't have generics
934 // and thus don't care about the parameter environment. While we could just use
935 // `self.param_env`, that would mean we invoke the query to evaluate the static
936 // with different parameter environments, thus causing the static to be evaluated
938 let param_env = if self.tcx.is_static(gid.instance.def_id()) {
939 ty::ParamEnv::reveal_all()
943 let param_env = param_env.with_const();
944 let val = self.tcx.eval_to_allocation_raw(param_env.and(gid))?;
945 self.raw_const_to_mplace(val)
949 pub fn dump_place(&self, place: Place<M::PointerTag>) -> PlacePrinter<'_, 'mir, 'tcx, M> {
950 PlacePrinter { ecx: self, place }
954 pub fn generate_stacktrace(&self) -> Vec<FrameInfo<'tcx>> {
955 let mut frames = Vec::new();
960 .skip_while(|frame| frame.instance.def.requires_caller_location(*self.tcx))
962 let lint_root = frame.current_source_info().and_then(|source_info| {
963 match &frame.body.source_scopes[source_info.scope].local_data {
964 mir::ClearCrossCrate::Set(data) => Some(data.lint_root),
965 mir::ClearCrossCrate::Clear => None,
968 let span = frame.current_span();
970 frames.push(FrameInfo { span, instance: frame.instance, lint_root });
972 trace!("generate stacktrace: {:#?}", frames);
978 /// Helper struct for the `dump_place` function.
979 pub struct PlacePrinter<'a, 'mir, 'tcx, M: Machine<'mir, 'tcx>> {
980 ecx: &'a InterpCx<'mir, 'tcx, M>,
981 place: Place<M::PointerTag>,
984 impl<'a, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> std::fmt::Debug
985 for PlacePrinter<'a, 'mir, 'tcx, M>
987 fn fmt(&self, fmt: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
989 Place::Local { frame, local } => {
990 let mut allocs = Vec::new();
991 write!(fmt, "{:?}", local)?;
992 if frame != self.ecx.frame_idx() {
993 write!(fmt, " ({} frames up)", self.ecx.frame_idx() - frame)?;
997 match self.ecx.stack()[frame].locals[local].value {
998 LocalValue::Dead => write!(fmt, " is dead")?,
999 LocalValue::Uninitialized => write!(fmt, " is uninitialized")?,
1000 LocalValue::Live(Operand::Indirect(mplace)) => {
1003 " by align({}){} ref {:?}:",
1004 mplace.align.bytes(),
1006 MemPlaceMeta::Meta(meta) => format!(" meta({:?})", meta),
1007 MemPlaceMeta::Poison | MemPlaceMeta::None => String::new(),
1011 allocs.extend(mplace.ptr.provenance.map(Provenance::get_alloc_id));
1013 LocalValue::Live(Operand::Immediate(Immediate::Scalar(val))) => {
1014 write!(fmt, " {:?}", val)?;
1015 if let ScalarMaybeUninit::Scalar(Scalar::Ptr(ptr, _size)) = val {
1016 allocs.push(ptr.provenance.get_alloc_id());
1019 LocalValue::Live(Operand::Immediate(Immediate::ScalarPair(val1, val2))) => {
1020 write!(fmt, " ({:?}, {:?})", val1, val2)?;
1021 if let ScalarMaybeUninit::Scalar(Scalar::Ptr(ptr, _size)) = val1 {
1022 allocs.push(ptr.provenance.get_alloc_id());
1024 if let ScalarMaybeUninit::Scalar(Scalar::Ptr(ptr, _size)) = val2 {
1025 allocs.push(ptr.provenance.get_alloc_id());
1030 write!(fmt, ": {:?}", self.ecx.memory.dump_allocs(allocs))
1032 Place::Ptr(mplace) => match mplace.ptr.provenance.map(Provenance::get_alloc_id) {
1033 Some(alloc_id) => write!(
1035 "by align({}) ref {:?}: {:?}",
1036 mplace.align.bytes(),
1038 self.ecx.memory.dump_alloc(alloc_id)
1040 ptr => write!(fmt, " integral by ref: {:?}", ptr),
1046 impl<'ctx, 'mir, 'tcx, Tag: Provenance, Extra> HashStable<StableHashingContext<'ctx>>
1047 for Frame<'mir, 'tcx, Tag, Extra>
1049 Extra: HashStable<StableHashingContext<'ctx>>,
1050 Tag: HashStable<StableHashingContext<'ctx>>,
1052 fn hash_stable(&self, hcx: &mut StableHashingContext<'ctx>, hasher: &mut StableHasher) {
1053 // Exhaustive match on fields to make sure we forget no field.
1064 body.hash_stable(hcx, hasher);
1065 instance.hash_stable(hcx, hasher);
1066 return_to_block.hash_stable(hcx, hasher);
1067 return_place.as_ref().map(|r| &**r).hash_stable(hcx, hasher);
1068 locals.hash_stable(hcx, hasher);
1069 loc.hash_stable(hcx, hasher);
1070 extra.hash_stable(hcx, hasher);