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 AllocCheck, AllocId, GlobalId, Immediate, InterpErrorInfo, InterpResult, MPlaceTy, Machine,
26 MemPlace, MemPlaceMeta, Memory, MemoryKind, Operand, Place, PlaceTy, Pointer, Provenance,
27 Scalar, 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 /// The root frame of the stack: nowhere else to jump to.
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 Root { 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 /// Test if this value might be null.
444 /// If the machine does not support ptr-to-int casts, this is conservative.
445 pub fn scalar_may_be_null(&self, scalar: Scalar<M::PointerTag>) -> bool {
446 match scalar.try_to_int() {
447 Ok(int) => int.is_null(),
449 let ptr = self.scalar_to_ptr(scalar);
450 match self.memory.ptr_try_get_alloc(ptr) {
451 Ok((alloc_id, offset, _)) => {
452 let (size, _align) = self
454 .get_size_and_align(alloc_id, AllocCheck::MaybeDead)
455 .expect("alloc info with MaybeDead cannot fail");
456 // If the pointer is out-of-bounds, it may be null.
457 // Note that one-past-the-end (offset == size) is still inbounds, and never null.
460 Err(offset) => offset == 0,
466 /// Call this to turn untagged "global" pointers (obtained via `tcx`) into
467 /// the machine pointer to the allocation. Must never be used
468 /// for any other pointers, nor for TLS statics.
470 /// Using the resulting pointer represents a *direct* access to that memory
471 /// (e.g. by directly using a `static`),
472 /// as opposed to access through a pointer that was created by the program.
474 /// This function can fail only if `ptr` points to an `extern static`.
476 pub fn global_base_pointer(&self, ptr: Pointer) -> InterpResult<'tcx, Pointer<M::PointerTag>> {
477 self.memory.global_base_pointer(ptr)
481 pub(crate) fn stack(&self) -> &[Frame<'mir, 'tcx, M::PointerTag, M::FrameExtra>] {
486 pub(crate) fn stack_mut(
488 ) -> &mut Vec<Frame<'mir, 'tcx, M::PointerTag, M::FrameExtra>> {
493 pub fn frame_idx(&self) -> usize {
494 let stack = self.stack();
495 assert!(!stack.is_empty());
500 pub fn frame(&self) -> &Frame<'mir, 'tcx, M::PointerTag, M::FrameExtra> {
501 self.stack().last().expect("no call frames exist")
505 pub fn frame_mut(&mut self) -> &mut Frame<'mir, 'tcx, M::PointerTag, M::FrameExtra> {
506 self.stack_mut().last_mut().expect("no call frames exist")
510 pub(super) fn body(&self) -> &'mir mir::Body<'tcx> {
515 pub fn sign_extend(&self, value: u128, ty: TyAndLayout<'_>) -> u128 {
516 assert!(ty.abi.is_signed());
517 ty.size.sign_extend(value)
521 pub fn truncate(&self, value: u128, ty: TyAndLayout<'_>) -> u128 {
522 ty.size.truncate(value)
526 pub fn type_is_freeze(&self, ty: Ty<'tcx>) -> bool {
527 ty.is_freeze(self.tcx, self.param_env)
532 instance: ty::InstanceDef<'tcx>,
533 promoted: Option<mir::Promoted>,
534 ) -> InterpResult<'tcx, &'tcx mir::Body<'tcx>> {
535 let def = instance.with_opt_param();
536 trace!("load mir(instance={:?}, promoted={:?})", instance, promoted);
537 let body = if let Some(promoted) = promoted {
538 &self.tcx.promoted_mir_opt_const_arg(def)[promoted]
540 M::load_mir(self, instance)?
542 // do not continue if typeck errors occurred (can only occur in local crate)
543 if let Some(err) = body.tainted_by_errors {
544 throw_inval!(AlreadyReported(err));
549 /// Call this on things you got out of the MIR (so it is as generic as the current
550 /// stack frame), to bring it into the proper environment for this interpreter.
551 pub(super) fn subst_from_current_frame_and_normalize_erasing_regions<T: TypeFoldable<'tcx>>(
554 ) -> Result<T, InterpError<'tcx>> {
555 self.subst_from_frame_and_normalize_erasing_regions(self.frame(), value)
558 /// Call this on things you got out of the MIR (so it is as generic as the provided
559 /// stack frame), to bring it into the proper environment for this interpreter.
560 pub(super) fn subst_from_frame_and_normalize_erasing_regions<T: TypeFoldable<'tcx>>(
562 frame: &Frame<'mir, 'tcx, M::PointerTag, M::FrameExtra>,
564 ) -> Result<T, InterpError<'tcx>> {
567 .try_subst_mir_and_normalize_erasing_regions(*self.tcx, self.param_env, value)
569 self.tcx.sess.delay_span_bug(
571 format!("failed to normalize {}", e.get_type_for_failure()).as_str(),
574 Err(InterpError::InvalidProgram(InvalidProgramInfo::TooGeneric))
578 /// The `substs` are assumed to already be in our interpreter "universe" (param_env).
579 pub(super) fn resolve(
581 def: ty::WithOptConstParam<DefId>,
582 substs: SubstsRef<'tcx>,
583 ) -> InterpResult<'tcx, ty::Instance<'tcx>> {
584 trace!("resolve: {:?}, {:#?}", def, substs);
585 trace!("param_env: {:#?}", self.param_env);
586 trace!("substs: {:#?}", substs);
587 match ty::Instance::resolve_opt_const_arg(*self.tcx, self.param_env, def, substs) {
588 Ok(Some(instance)) => Ok(instance),
589 Ok(None) => throw_inval!(TooGeneric),
591 // FIXME(eddyb) this could be a bit more specific than `AlreadyReported`.
592 Err(error_reported) => throw_inval!(AlreadyReported(error_reported)),
597 pub fn layout_of_local(
599 frame: &Frame<'mir, 'tcx, M::PointerTag, M::FrameExtra>,
601 layout: Option<TyAndLayout<'tcx>>,
602 ) -> InterpResult<'tcx, TyAndLayout<'tcx>> {
603 // `const_prop` runs into this with an invalid (empty) frame, so we
604 // have to support that case (mostly by skipping all caching).
605 match frame.locals.get(local).and_then(|state| state.layout.get()) {
607 let layout = from_known_layout(self.tcx, self.param_env, layout, || {
608 let local_ty = frame.body.local_decls[local].ty;
610 self.subst_from_frame_and_normalize_erasing_regions(frame, local_ty)?;
611 self.layout_of(local_ty)
613 if let Some(state) = frame.locals.get(local) {
614 // Layouts of locals are requested a lot, so we cache them.
615 state.layout.set(Some(layout));
619 Some(layout) => Ok(layout),
623 /// Returns the actual dynamic size and alignment of the place at the given type.
624 /// Only the "meta" (metadata) part of the place matters.
625 /// This can fail to provide an answer for extern types.
626 pub(super) fn size_and_align_of(
628 metadata: &MemPlaceMeta<M::PointerTag>,
629 layout: &TyAndLayout<'tcx>,
630 ) -> InterpResult<'tcx, Option<(Size, Align)>> {
631 if !layout.is_unsized() {
632 return Ok(Some((layout.size, layout.align.abi)));
634 match layout.ty.kind() {
635 ty::Adt(..) | ty::Tuple(..) => {
636 // First get the size of all statically known fields.
637 // Don't use type_of::sizing_type_of because that expects t to be sized,
638 // and it also rounds up to alignment, which we want to avoid,
639 // as the unsized field's alignment could be smaller.
640 assert!(!layout.ty.is_simd());
641 assert!(layout.fields.count() > 0);
642 trace!("DST layout: {:?}", layout);
644 let sized_size = layout.fields.offset(layout.fields.count() - 1);
645 let sized_align = layout.align.abi;
647 "DST {} statically sized prefix size: {:?} align: {:?}",
653 // Recurse to get the size of the dynamically sized field (must be
654 // the last field). Can't have foreign types here, how would we
655 // adjust alignment and size for them?
656 let field = layout.field(self, layout.fields.count() - 1);
657 let Some((unsized_size, unsized_align)) = self.size_and_align_of(metadata, &field)? else {
658 // A field with an extern type. We don't know the actual dynamic size
663 // FIXME (#26403, #27023): We should be adding padding
664 // to `sized_size` (to accommodate the `unsized_align`
665 // required of the unsized field that follows) before
666 // summing it with `sized_size`. (Note that since #26403
667 // is unfixed, we do not yet add the necessary padding
668 // here. But this is where the add would go.)
670 // Return the sum of sizes and max of aligns.
671 let size = sized_size + unsized_size; // `Size` addition
673 // Choose max of two known alignments (combined value must
674 // be aligned according to more restrictive of the two).
675 let align = sized_align.max(unsized_align);
677 // Issue #27023: must add any necessary padding to `size`
678 // (to make it a multiple of `align`) before returning it.
679 let size = size.align_to(align);
681 // Check if this brought us over the size limit.
682 if size.bytes() >= self.tcx.data_layout.obj_size_bound() {
683 throw_ub!(InvalidMeta("total size is bigger than largest supported object"));
685 Ok(Some((size, align)))
688 let vtable = self.scalar_to_ptr(metadata.unwrap_meta());
689 // Read size and align from vtable (already checks size).
690 Ok(Some(self.read_size_and_align_from_vtable(vtable)?))
693 ty::Slice(_) | ty::Str => {
694 let len = metadata.unwrap_meta().to_machine_usize(self)?;
695 let elem = layout.field(self, 0);
697 // Make sure the slice is not too big.
698 let size = elem.size.checked_mul(len, self).ok_or_else(|| {
699 err_ub!(InvalidMeta("slice is bigger than largest supported object"))
701 Ok(Some((size, elem.align.abi)))
704 ty::Foreign(_) => Ok(None),
706 _ => span_bug!(self.cur_span(), "size_and_align_of::<{:?}> not supported", layout.ty),
710 pub fn size_and_align_of_mplace(
712 mplace: &MPlaceTy<'tcx, M::PointerTag>,
713 ) -> InterpResult<'tcx, Option<(Size, Align)>> {
714 self.size_and_align_of(&mplace.meta, &mplace.layout)
717 pub fn push_stack_frame(
719 instance: ty::Instance<'tcx>,
720 body: &'mir mir::Body<'tcx>,
721 return_place: Option<&PlaceTy<'tcx, M::PointerTag>>,
722 return_to_block: StackPopCleanup,
723 ) -> InterpResult<'tcx> {
724 // first push a stack frame so we have access to the local substs
725 let pre_frame = Frame {
727 loc: Err(body.span), // Span used for errors caused during preamble.
729 return_place: return_place.copied(),
730 // empty local array, we fill it in below, after we are inside the stack frame and
731 // all methods actually know about the frame
732 locals: IndexVec::new(),
734 tracing_span: SpanGuard::new(),
737 let frame = M::init_frame_extra(self, pre_frame)?;
738 self.stack_mut().push(frame);
740 // Make sure all the constants required by this frame evaluate successfully (post-monomorphization check).
741 for const_ in &body.required_consts {
742 let span = const_.span;
744 self.subst_from_current_frame_and_normalize_erasing_regions(const_.literal)?;
745 self.mir_const_to_op(&const_, None).map_err(|err| {
746 // If there was an error, set the span of the current frame to this constant.
747 // Avoiding doing this when evaluation succeeds.
748 self.frame_mut().loc = Err(span);
753 // Locals are initially uninitialized.
754 let dummy = LocalState { value: LocalValue::Uninitialized, layout: Cell::new(None) };
755 let mut locals = IndexVec::from_elem(dummy, &body.local_decls);
757 // Now mark those locals as dead that we do not want to initialize
758 // Mark locals that use `Storage*` annotations as dead on function entry.
759 let always_live = AlwaysLiveLocals::new(self.body());
760 for local in locals.indices() {
761 if !always_live.contains(local) {
762 locals[local].value = LocalValue::Dead;
766 self.frame_mut().locals = locals;
767 M::after_stack_push(self)?;
768 self.frame_mut().loc = Ok(mir::Location::START);
770 let span = info_span!("frame", "{}", instance);
771 self.frame_mut().tracing_span.enter(span);
776 /// Jump to the given block.
778 pub fn go_to_block(&mut self, target: mir::BasicBlock) {
779 self.frame_mut().loc = Ok(mir::Location { block: target, statement_index: 0 });
782 /// *Return* to the given `target` basic block.
783 /// Do *not* use for unwinding! Use `unwind_to_block` instead.
785 /// If `target` is `None`, that indicates the function cannot return, so we raise UB.
786 pub fn return_to_block(&mut self, target: Option<mir::BasicBlock>) -> InterpResult<'tcx> {
787 if let Some(target) = target {
788 self.go_to_block(target);
791 throw_ub!(Unreachable)
795 /// *Unwind* to the given `target` basic block.
796 /// Do *not* use for returning! Use `return_to_block` instead.
798 /// If `target` is `StackPopUnwind::Skip`, that indicates the function does not need cleanup
799 /// during unwinding, and we will just keep propagating that upwards.
801 /// If `target` is `StackPopUnwind::NotAllowed`, that indicates the function does not allow
802 /// unwinding, and doing so is UB.
803 pub fn unwind_to_block(&mut self, target: StackPopUnwind) -> InterpResult<'tcx> {
804 self.frame_mut().loc = match target {
805 StackPopUnwind::Cleanup(block) => Ok(mir::Location { block, statement_index: 0 }),
806 StackPopUnwind::Skip => Err(self.frame_mut().body.span),
807 StackPopUnwind::NotAllowed => {
808 throw_ub_format!("unwinding past a stack frame that does not allow unwinding")
814 /// Pops the current frame from the stack, deallocating the
815 /// memory for allocated locals.
817 /// If `unwinding` is `false`, then we are performing a normal return
818 /// from a function. In this case, we jump back into the frame of the caller,
819 /// and continue execution as normal.
821 /// If `unwinding` is `true`, then we are in the middle of a panic,
822 /// and need to unwind this frame. In this case, we jump to the
823 /// `cleanup` block for the function, which is responsible for running
824 /// `Drop` impls for any locals that have been initialized at this point.
825 /// The cleanup block ends with a special `Resume` terminator, which will
826 /// cause us to continue unwinding.
827 pub(super) fn pop_stack_frame(&mut self, unwinding: bool) -> InterpResult<'tcx> {
829 "popping stack frame ({})",
830 if unwinding { "during unwinding" } else { "returning from function" }
833 // Sanity check `unwinding`.
836 match self.frame().loc {
837 Ok(loc) => self.body().basic_blocks()[loc.block].is_cleanup,
842 if unwinding && self.frame_idx() == 0 {
843 throw_ub_format!("unwinding past the topmost frame of the stack");
847 self.stack_mut().pop().expect("tried to pop a stack frame, but there were none");
850 // Copy the return value to the caller's stack frame.
851 if let Some(ref return_place) = frame.return_place {
852 let op = self.access_local(&frame, mir::RETURN_PLACE, None)?;
853 self.copy_op_transmute(&op, return_place)?;
854 trace!("{:?}", self.dump_place(**return_place));
856 throw_ub!(Unreachable);
860 let return_to_block = frame.return_to_block;
862 // Now where do we jump next?
864 // Usually we want to clean up (deallocate locals), but in a few rare cases we don't.
865 // In that case, we return early. We also avoid validation in that case,
866 // because this is CTFE and the final value will be thoroughly validated anyway.
867 let cleanup = match return_to_block {
868 StackPopCleanup::Goto { .. } => true,
869 StackPopCleanup::Root { cleanup, .. } => cleanup,
873 assert!(self.stack().is_empty(), "only the topmost frame should ever be leaked");
874 assert!(!unwinding, "tried to skip cleanup during unwinding");
875 // Leak the locals, skip validation, skip machine hook.
879 // Cleanup: deallocate all locals that are backed by an allocation.
880 for local in &frame.locals {
881 self.deallocate_local(local.value)?;
884 if M::after_stack_pop(self, frame, unwinding)? == StackPopJump::NoJump {
885 // The hook already did everything.
886 // We want to skip the `info!` below, hence early return.
889 // Normal return, figure out where to jump.
891 // Follow the unwind edge.
892 let unwind = match return_to_block {
893 StackPopCleanup::Goto { unwind, .. } => unwind,
894 StackPopCleanup::Root { .. } => {
895 panic!("encountered StackPopCleanup::Root when unwinding!")
898 self.unwind_to_block(unwind)
900 // Follow the normal return edge.
901 match return_to_block {
902 StackPopCleanup::Goto { ret, .. } => self.return_to_block(ret),
903 StackPopCleanup::Root { .. } => {
905 self.stack().is_empty(),
906 "only the topmost frame can have StackPopCleanup::Root"
914 /// Mark a storage as live, killing the previous content.
915 pub fn storage_live(&mut self, local: mir::Local) -> InterpResult<'tcx> {
916 assert!(local != mir::RETURN_PLACE, "Cannot make return place live");
917 trace!("{:?} is now live", local);
919 let local_val = LocalValue::Uninitialized;
920 // StorageLive expects the local to be dead, and marks it live.
921 let old = mem::replace(&mut self.frame_mut().locals[local].value, local_val);
922 if !matches!(old, LocalValue::Dead) {
923 throw_ub_format!("StorageLive on a local that was already live");
928 pub fn storage_dead(&mut self, local: mir::Local) -> InterpResult<'tcx> {
929 assert!(local != mir::RETURN_PLACE, "Cannot make return place dead");
930 trace!("{:?} is now dead", local);
932 // It is entirely okay for this local to be already dead (at least that's how we currently generate MIR)
933 let old = mem::replace(&mut self.frame_mut().locals[local].value, LocalValue::Dead);
934 self.deallocate_local(old)?;
938 fn deallocate_local(&mut self, local: LocalValue<M::PointerTag>) -> InterpResult<'tcx> {
939 if let LocalValue::Live(Operand::Indirect(MemPlace { ptr, .. })) = local {
940 // All locals have a backing allocation, even if the allocation is empty
941 // due to the local having ZST type. Hence we can `unwrap`.
943 "deallocating local {:?}: {:?}",
945 self.memory.dump_alloc(ptr.provenance.unwrap().get_alloc_id())
947 self.memory.deallocate(ptr, None, MemoryKind::Stack)?;
952 pub fn eval_to_allocation(
955 ) -> InterpResult<'tcx, MPlaceTy<'tcx, M::PointerTag>> {
956 // For statics we pick `ParamEnv::reveal_all`, because statics don't have generics
957 // and thus don't care about the parameter environment. While we could just use
958 // `self.param_env`, that would mean we invoke the query to evaluate the static
959 // with different parameter environments, thus causing the static to be evaluated
961 let param_env = if self.tcx.is_static(gid.instance.def_id()) {
962 ty::ParamEnv::reveal_all()
966 let param_env = param_env.with_const();
967 let val = self.tcx.eval_to_allocation_raw(param_env.and(gid))?;
968 self.raw_const_to_mplace(val)
972 pub fn dump_place(&self, place: Place<M::PointerTag>) -> PlacePrinter<'_, 'mir, 'tcx, M> {
973 PlacePrinter { ecx: self, place }
977 pub fn generate_stacktrace(&self) -> Vec<FrameInfo<'tcx>> {
978 let mut frames = Vec::new();
983 .skip_while(|frame| frame.instance.def.requires_caller_location(*self.tcx))
985 let lint_root = frame.current_source_info().and_then(|source_info| {
986 match &frame.body.source_scopes[source_info.scope].local_data {
987 mir::ClearCrossCrate::Set(data) => Some(data.lint_root),
988 mir::ClearCrossCrate::Clear => None,
991 let span = frame.current_span();
993 frames.push(FrameInfo { span, instance: frame.instance, lint_root });
995 trace!("generate stacktrace: {:#?}", frames);
1001 /// Helper struct for the `dump_place` function.
1002 pub struct PlacePrinter<'a, 'mir, 'tcx, M: Machine<'mir, 'tcx>> {
1003 ecx: &'a InterpCx<'mir, 'tcx, M>,
1004 place: Place<M::PointerTag>,
1007 impl<'a, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> std::fmt::Debug
1008 for PlacePrinter<'a, 'mir, 'tcx, M>
1010 fn fmt(&self, fmt: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
1012 Place::Local { frame, local } => {
1013 let mut allocs = Vec::new();
1014 write!(fmt, "{:?}", local)?;
1015 if frame != self.ecx.frame_idx() {
1016 write!(fmt, " ({} frames up)", self.ecx.frame_idx() - frame)?;
1020 match self.ecx.stack()[frame].locals[local].value {
1021 LocalValue::Dead => write!(fmt, " is dead")?,
1022 LocalValue::Uninitialized => write!(fmt, " is uninitialized")?,
1023 LocalValue::Live(Operand::Indirect(mplace)) => {
1026 " by align({}){} ref {:?}:",
1027 mplace.align.bytes(),
1029 MemPlaceMeta::Meta(meta) => format!(" meta({:?})", meta),
1030 MemPlaceMeta::Poison | MemPlaceMeta::None => String::new(),
1034 allocs.extend(mplace.ptr.provenance.map(Provenance::get_alloc_id));
1036 LocalValue::Live(Operand::Immediate(Immediate::Scalar(val))) => {
1037 write!(fmt, " {:?}", val)?;
1038 if let ScalarMaybeUninit::Scalar(Scalar::Ptr(ptr, _size)) = val {
1039 allocs.push(ptr.provenance.get_alloc_id());
1042 LocalValue::Live(Operand::Immediate(Immediate::ScalarPair(val1, val2))) => {
1043 write!(fmt, " ({:?}, {:?})", val1, val2)?;
1044 if let ScalarMaybeUninit::Scalar(Scalar::Ptr(ptr, _size)) = val1 {
1045 allocs.push(ptr.provenance.get_alloc_id());
1047 if let ScalarMaybeUninit::Scalar(Scalar::Ptr(ptr, _size)) = val2 {
1048 allocs.push(ptr.provenance.get_alloc_id());
1053 write!(fmt, ": {:?}", self.ecx.memory.dump_allocs(allocs))
1055 Place::Ptr(mplace) => match mplace.ptr.provenance.map(Provenance::get_alloc_id) {
1056 Some(alloc_id) => write!(
1058 "by align({}) ref {:?}: {:?}",
1059 mplace.align.bytes(),
1061 self.ecx.memory.dump_alloc(alloc_id)
1063 ptr => write!(fmt, " integral by ref: {:?}", ptr),
1069 impl<'ctx, 'mir, 'tcx, Tag: Provenance, Extra> HashStable<StableHashingContext<'ctx>>
1070 for Frame<'mir, 'tcx, Tag, Extra>
1072 Extra: HashStable<StableHashingContext<'ctx>>,
1073 Tag: HashStable<StableHashingContext<'ctx>>,
1075 fn hash_stable(&self, hcx: &mut StableHashingContext<'ctx>, hasher: &mut StableHasher) {
1076 // Exhaustive match on fields to make sure we forget no field.
1087 body.hash_stable(hcx, hasher);
1088 instance.hash_stable(hcx, hasher);
1089 return_to_block.hash_stable(hcx, hasher);
1090 return_place.as_ref().map(|r| &**r).hash_stable(hcx, hasher);
1091 locals.hash_stable(hcx, hasher);
1092 loc.hash_stable(hcx, hasher);
1093 extra.hash_stable(hcx, hasher);