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;
9 use rustc_middle::ich::StableHashingContext;
10 use rustc_middle::mir;
11 use rustc_middle::ty::layout::{self, TyAndLayout};
12 use rustc_middle::ty::{
13 self, query::TyCtxtAt, subst::SubstsRef, ParamEnv, Ty, TyCtxt, TypeFoldable,
15 use rustc_session::Limit;
16 use rustc_span::{Pos, Span};
17 use rustc_target::abi::{Align, HasDataLayout, LayoutOf, Size, TargetDataLayout};
20 AllocId, GlobalId, Immediate, InterpResult, MPlaceTy, Machine, MemPlace, MemPlaceMeta, Memory,
21 MemoryKind, Operand, Place, PlaceTy, Pointer, Provenance, Scalar, ScalarMaybeUninit,
24 use crate::transform::validate::equal_up_to_regions;
25 use crate::util::storage::AlwaysLiveLocals;
27 pub struct InterpCx<'mir, 'tcx, M: Machine<'mir, 'tcx>> {
28 /// Stores the `Machine` instance.
30 /// Note: the stack is provided by the machine.
33 /// The results of the type checker, from rustc.
34 /// The span in this is the "root" of the evaluation, i.e., the const
35 /// we are evaluating (if this is CTFE).
36 pub tcx: TyCtxtAt<'tcx>,
38 /// Bounds in scope for polymorphic evaluations.
39 pub(crate) param_env: ty::ParamEnv<'tcx>,
41 /// The virtual memory system.
42 pub memory: Memory<'mir, 'tcx, M>,
44 /// The recursion limit (cached from `tcx.recursion_limit(())`)
45 pub recursion_limit: Limit,
48 // The Phantomdata exists to prevent this type from being `Send`. If it were sent across a thread
49 // boundary and dropped in the other thread, it would exit the span in the other thread.
50 struct SpanGuard(tracing::Span, std::marker::PhantomData<*const u8>);
53 /// By default a `SpanGuard` does nothing.
55 Self(tracing::Span::none(), std::marker::PhantomData)
58 /// If a span is entered, we exit the previous span (if any, normally none) and enter the
59 /// new span. This is mainly so we don't have to use `Option` for the `tracing_span` field of
60 /// `Frame` by creating a dummy span to being with and then entering it once the frame has
62 fn enter(&mut self, span: tracing::Span) {
63 // This executes the destructor on the previous instance of `SpanGuard`, ensuring that
64 // we never enter or exit more spans than vice versa. Unless you `mem::leak`, then we
65 // can't protect the tracing stack, but that'll just lead to weird logging, no actual
67 *self = Self(span, std::marker::PhantomData);
68 self.0.with_subscriber(|(id, dispatch)| {
74 impl Drop for SpanGuard {
76 self.0.with_subscriber(|(id, dispatch)| {
83 pub struct Frame<'mir, 'tcx, Tag = AllocId, Extra = ()> {
84 ////////////////////////////////////////////////////////////////////////////////
85 // Function and callsite information
86 ////////////////////////////////////////////////////////////////////////////////
87 /// The MIR for the function called on this frame.
88 pub body: &'mir mir::Body<'tcx>,
90 /// The def_id and substs of the current function.
91 pub instance: ty::Instance<'tcx>,
93 /// Extra data for the machine.
96 ////////////////////////////////////////////////////////////////////////////////
97 // Return place and locals
98 ////////////////////////////////////////////////////////////////////////////////
99 /// Work to perform when returning from this function.
100 pub return_to_block: StackPopCleanup,
102 /// The location where the result of the current stack frame should be written to,
103 /// and its layout in the caller.
104 pub return_place: Option<PlaceTy<'tcx, Tag>>,
106 /// The list of locals for this stack frame, stored in order as
107 /// `[return_ptr, arguments..., variables..., temporaries...]`.
108 /// The locals are stored as `Option<Value>`s.
109 /// `None` represents a local that is currently dead, while a live local
110 /// can either directly contain `Scalar` or refer to some part of an `Allocation`.
111 pub locals: IndexVec<mir::Local, LocalState<'tcx, Tag>>,
113 /// The span of the `tracing` crate is stored here.
114 /// When the guard is dropped, the span is exited. This gives us
115 /// a full stack trace on all tracing statements.
116 tracing_span: SpanGuard,
118 ////////////////////////////////////////////////////////////////////////////////
119 // Current position within the function
120 ////////////////////////////////////////////////////////////////////////////////
121 /// If this is `Err`, we are not currently executing any particular statement in
122 /// this frame (can happen e.g. during frame initialization, and during unwinding on
123 /// frames without cleanup code).
124 /// We basically abuse `Result` as `Either`.
125 pub(super) loc: Result<mir::Location, Span>,
128 /// What we store about a frame in an interpreter backtrace.
130 pub struct FrameInfo<'tcx> {
131 pub instance: ty::Instance<'tcx>,
133 pub lint_root: Option<hir::HirId>,
136 /// Unwind information.
137 #[derive(Clone, Copy, Eq, PartialEq, Debug, HashStable)]
138 pub enum StackPopUnwind {
139 /// The cleanup block.
140 Cleanup(mir::BasicBlock),
141 /// No cleanup needs to be done.
143 /// Unwinding is not allowed (UB).
147 #[derive(Clone, Copy, Eq, PartialEq, Debug, HashStable)] // Miri debug-prints these
148 pub enum StackPopCleanup {
149 /// Jump to the next block in the caller, or cause UB if None (that's a function
150 /// that may never return). Also store layout of return place so
151 /// we can validate it at that layout.
152 /// `ret` stores the block we jump to on a normal return, while `unwind`
153 /// stores the block used for cleanup during unwinding.
154 Goto { ret: Option<mir::BasicBlock>, unwind: StackPopUnwind },
155 /// Just do nothing: Used by Main and for the `box_alloc` hook in miri.
156 /// `cleanup` says whether locals are deallocated. Static computation
157 /// wants them leaked to intern what they need (and just throw away
158 /// the entire `ecx` when it is done).
159 None { cleanup: bool },
162 /// State of a local variable including a memoized layout
163 #[derive(Clone, PartialEq, Eq, HashStable)]
164 pub struct LocalState<'tcx, Tag = AllocId> {
165 pub value: LocalValue<Tag>,
166 /// Don't modify if `Some`, this is only used to prevent computing the layout twice
167 #[stable_hasher(ignore)]
168 pub layout: Cell<Option<TyAndLayout<'tcx>>>,
171 /// Current value of a local variable
172 #[derive(Copy, Clone, PartialEq, Eq, HashStable)]
173 pub enum LocalValue<Tag = AllocId> {
174 /// This local is not currently alive, and cannot be used at all.
176 /// This local is alive but not yet initialized. It can be written to
177 /// but not read from or its address taken. Locals get initialized on
178 /// first write because for unsized locals, we do not know their size
181 /// A normal, live local.
182 /// Mostly for convenience, we re-use the `Operand` type here.
183 /// This is an optimization over just always having a pointer here;
184 /// we can thus avoid doing an allocation when the local just stores
185 /// immediate values *and* never has its address taken.
189 impl<Tag: Provenance> std::fmt::Debug for LocalValue<Tag> {
190 // Miri debug-prints these
191 fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
194 Dead => f.debug_tuple("Dead").finish(),
195 Uninitialized => f.debug_tuple("Uninitialized").finish(),
196 Live(o) => f.debug_tuple("Live").field(o).finish(),
201 impl<'tcx, Tag: Copy + 'static> LocalState<'tcx, Tag> {
202 /// Read the local's value or error if the local is not yet live or not live anymore.
204 /// Note: This may only be invoked from the `Machine::access_local` hook and not from
205 /// anywhere else. You may be invalidating machine invariants if you do!
206 pub fn access(&self) -> InterpResult<'tcx, Operand<Tag>> {
208 LocalValue::Dead => throw_ub!(DeadLocal),
209 LocalValue::Uninitialized => {
210 bug!("The type checker should prevent reading from a never-written local")
212 LocalValue::Live(val) => Ok(val),
216 /// Overwrite the local. If the local can be overwritten in place, return a reference
217 /// to do so; otherwise return the `MemPlace` to consult instead.
219 /// Note: This may only be invoked from the `Machine::access_local_mut` hook and not from
220 /// anywhere else. You may be invalidating machine invariants if you do!
223 ) -> InterpResult<'tcx, Result<&mut LocalValue<Tag>, MemPlace<Tag>>> {
225 LocalValue::Dead => throw_ub!(DeadLocal),
226 LocalValue::Live(Operand::Indirect(mplace)) => Ok(Err(mplace)),
228 local @ (LocalValue::Live(Operand::Immediate(_)) | LocalValue::Uninitialized) => {
235 impl<'mir, 'tcx, Tag> Frame<'mir, 'tcx, Tag> {
236 pub fn with_extra<Extra>(self, extra: Extra) -> Frame<'mir, 'tcx, Tag, Extra> {
239 instance: self.instance,
240 return_to_block: self.return_to_block,
241 return_place: self.return_place,
245 tracing_span: self.tracing_span,
250 impl<'mir, 'tcx, Tag, Extra> Frame<'mir, 'tcx, Tag, Extra> {
251 /// Get the current location within the Frame.
253 /// If this is `Err`, we are not currently executing any particular statement in
254 /// this frame (can happen e.g. during frame initialization, and during unwinding on
255 /// frames without cleanup code).
256 /// We basically abuse `Result` as `Either`.
259 pub fn current_loc(&self) -> Result<mir::Location, Span> {
263 /// Return the `SourceInfo` of the current instruction.
264 pub fn current_source_info(&self) -> Option<&mir::SourceInfo> {
265 self.loc.ok().map(|loc| self.body.source_info(loc))
268 pub fn current_span(&self) -> Span {
270 Ok(loc) => self.body.source_info(loc).span,
276 impl<'tcx> fmt::Display for FrameInfo<'tcx> {
277 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
278 ty::tls::with(|tcx| {
279 if tcx.def_key(self.instance.def_id()).disambiguated_data.data
280 == DefPathData::ClosureExpr
282 write!(f, "inside closure")?;
284 write!(f, "inside `{}`", self.instance)?;
286 if !self.span.is_dummy() {
287 let lo = tcx.sess.source_map().lookup_char_pos(self.span.lo());
291 lo.file.name.prefer_local(),
293 lo.col.to_usize() + 1
301 impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> HasDataLayout for InterpCx<'mir, 'tcx, M> {
303 fn data_layout(&self) -> &TargetDataLayout {
304 &self.tcx.data_layout
308 impl<'mir, 'tcx, M> layout::HasTyCtxt<'tcx> for InterpCx<'mir, 'tcx, M>
310 M: Machine<'mir, 'tcx>,
313 fn tcx(&self) -> TyCtxt<'tcx> {
318 impl<'mir, 'tcx, M> layout::HasParamEnv<'tcx> for InterpCx<'mir, 'tcx, M>
320 M: Machine<'mir, 'tcx>,
322 fn param_env(&self) -> ty::ParamEnv<'tcx> {
327 impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> LayoutOf for InterpCx<'mir, 'tcx, M> {
329 type TyAndLayout = InterpResult<'tcx, TyAndLayout<'tcx>>;
332 fn layout_of(&self, ty: Ty<'tcx>) -> Self::TyAndLayout {
334 .layout_of(self.param_env.and(ty))
335 .map_err(|layout| err_inval!(Layout(layout)).into())
339 /// Test if it is valid for a MIR assignment to assign `src`-typed place to `dest`-typed value.
340 /// This test should be symmetric, as it is primarily about layout compatibility.
341 pub(super) fn mir_assign_valid_types<'tcx>(
343 param_env: ParamEnv<'tcx>,
344 src: TyAndLayout<'tcx>,
345 dest: TyAndLayout<'tcx>,
347 // Type-changing assignments can happen when subtyping is used. While
348 // all normal lifetimes are erased, higher-ranked types with their
349 // late-bound lifetimes are still around and can lead to type
350 // differences. So we compare ignoring lifetimes.
351 if equal_up_to_regions(tcx, param_env, src.ty, dest.ty) {
352 // Make sure the layout is equal, too -- just to be safe. Miri really
353 // needs layout equality. For performance reason we skip this check when
354 // the types are equal. Equal types *can* have different layouts when
355 // enum downcast is involved (as enum variants carry the type of the
356 // enum), but those should never occur in assignments.
357 if cfg!(debug_assertions) || src.ty != dest.ty {
358 assert_eq!(src.layout, dest.layout);
366 /// Use the already known layout if given (but sanity check in debug mode),
367 /// or compute the layout.
368 #[cfg_attr(not(debug_assertions), inline(always))]
369 pub(super) fn from_known_layout<'tcx>(
371 param_env: ParamEnv<'tcx>,
372 known_layout: Option<TyAndLayout<'tcx>>,
373 compute: impl FnOnce() -> InterpResult<'tcx, TyAndLayout<'tcx>>,
374 ) -> InterpResult<'tcx, TyAndLayout<'tcx>> {
377 Some(known_layout) => {
378 if cfg!(debug_assertions) {
379 let check_layout = compute()?;
380 if !mir_assign_valid_types(tcx.tcx, param_env, check_layout, known_layout) {
383 "expected type differs from actual type.\nexpected: {:?}\nactual: {:?}",
394 impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
398 param_env: ty::ParamEnv<'tcx>,
400 memory_extra: M::MemoryExtra,
404 tcx: tcx.at(root_span),
406 memory: Memory::new(tcx, memory_extra),
407 recursion_limit: tcx.recursion_limit(),
412 pub fn cur_span(&self) -> Span {
416 .find(|frame| !frame.instance.def.requires_caller_location(*self.tcx))
417 .map_or(self.tcx.span, |f| f.current_span())
421 pub fn scalar_to_ptr(&self, scalar: Scalar<M::PointerTag>) -> Pointer<Option<M::PointerTag>> {
422 self.memory.scalar_to_ptr(scalar)
425 /// Call this to turn untagged "global" pointers (obtained via `tcx`) into
426 /// the machine pointer to the allocation. Must never be used
427 /// for any other pointers, nor for TLS statics.
429 /// Using the resulting pointer represents a *direct* access to that memory
430 /// (e.g. by directly using a `static`),
431 /// as opposed to access through a pointer that was created by the program.
433 /// This function can fail only if `ptr` points to an `extern static`.
435 pub fn global_base_pointer(&self, ptr: Pointer) -> InterpResult<'tcx, Pointer<M::PointerTag>> {
436 self.memory.global_base_pointer(ptr)
440 pub(crate) fn stack(&self) -> &[Frame<'mir, 'tcx, M::PointerTag, M::FrameExtra>] {
445 pub(crate) fn stack_mut(
447 ) -> &mut Vec<Frame<'mir, 'tcx, M::PointerTag, M::FrameExtra>> {
452 pub fn frame_idx(&self) -> usize {
453 let stack = self.stack();
454 assert!(!stack.is_empty());
459 pub fn frame(&self) -> &Frame<'mir, 'tcx, M::PointerTag, M::FrameExtra> {
460 self.stack().last().expect("no call frames exist")
464 pub fn frame_mut(&mut self) -> &mut Frame<'mir, 'tcx, M::PointerTag, M::FrameExtra> {
465 self.stack_mut().last_mut().expect("no call frames exist")
469 pub(super) fn body(&self) -> &'mir mir::Body<'tcx> {
474 pub fn sign_extend(&self, value: u128, ty: TyAndLayout<'_>) -> u128 {
475 assert!(ty.abi.is_signed());
476 ty.size.sign_extend(value)
480 pub fn truncate(&self, value: u128, ty: TyAndLayout<'_>) -> u128 {
481 ty.size.truncate(value)
485 pub fn type_is_freeze(&self, ty: Ty<'tcx>) -> bool {
486 ty.is_freeze(self.tcx, self.param_env)
491 instance: ty::InstanceDef<'tcx>,
492 promoted: Option<mir::Promoted>,
493 ) -> InterpResult<'tcx, &'tcx mir::Body<'tcx>> {
494 // do not continue if typeck errors occurred (can only occur in local crate)
495 let def = instance.with_opt_param();
496 if let Some(def) = def.as_local() {
497 if self.tcx.has_typeck_results(def.did) {
498 if let Some(error_reported) = self.tcx.typeck_opt_const_arg(def).tainted_by_errors {
499 throw_inval!(AlreadyReported(error_reported))
503 trace!("load mir(instance={:?}, promoted={:?})", instance, promoted);
504 if let Some(promoted) = promoted {
505 return Ok(&self.tcx.promoted_mir_opt_const_arg(def)[promoted]);
507 M::load_mir(self, instance)
510 /// Call this on things you got out of the MIR (so it is as generic as the current
511 /// stack frame), to bring it into the proper environment for this interpreter.
512 pub(super) fn subst_from_current_frame_and_normalize_erasing_regions<T: TypeFoldable<'tcx>>(
516 self.subst_from_frame_and_normalize_erasing_regions(self.frame(), value)
519 /// Call this on things you got out of the MIR (so it is as generic as the provided
520 /// stack frame), to bring it into the proper environment for this interpreter.
521 pub(super) fn subst_from_frame_and_normalize_erasing_regions<T: TypeFoldable<'tcx>>(
523 frame: &Frame<'mir, 'tcx, M::PointerTag, M::FrameExtra>,
526 frame.instance.subst_mir_and_normalize_erasing_regions(*self.tcx, self.param_env, value)
529 /// The `substs` are assumed to already be in our interpreter "universe" (param_env).
530 pub(super) fn resolve(
532 def: ty::WithOptConstParam<DefId>,
533 substs: SubstsRef<'tcx>,
534 ) -> InterpResult<'tcx, ty::Instance<'tcx>> {
535 trace!("resolve: {:?}, {:#?}", def, substs);
536 trace!("param_env: {:#?}", self.param_env);
537 trace!("substs: {:#?}", substs);
538 match ty::Instance::resolve_opt_const_arg(*self.tcx, self.param_env, def, substs) {
539 Ok(Some(instance)) => Ok(instance),
540 Ok(None) => throw_inval!(TooGeneric),
542 // FIXME(eddyb) this could be a bit more specific than `AlreadyReported`.
543 Err(error_reported) => throw_inval!(AlreadyReported(error_reported)),
548 pub fn layout_of_local(
550 frame: &Frame<'mir, 'tcx, M::PointerTag, M::FrameExtra>,
552 layout: Option<TyAndLayout<'tcx>>,
553 ) -> InterpResult<'tcx, TyAndLayout<'tcx>> {
554 // `const_prop` runs into this with an invalid (empty) frame, so we
555 // have to support that case (mostly by skipping all caching).
556 match frame.locals.get(local).and_then(|state| state.layout.get()) {
558 let layout = from_known_layout(self.tcx, self.param_env, layout, || {
559 let local_ty = frame.body.local_decls[local].ty;
561 self.subst_from_frame_and_normalize_erasing_regions(frame, local_ty);
562 self.layout_of(local_ty)
564 if let Some(state) = frame.locals.get(local) {
565 // Layouts of locals are requested a lot, so we cache them.
566 state.layout.set(Some(layout));
570 Some(layout) => Ok(layout),
574 /// Returns the actual dynamic size and alignment of the place at the given type.
575 /// Only the "meta" (metadata) part of the place matters.
576 /// This can fail to provide an answer for extern types.
577 pub(super) fn size_and_align_of(
579 metadata: &MemPlaceMeta<M::PointerTag>,
580 layout: &TyAndLayout<'tcx>,
581 ) -> InterpResult<'tcx, Option<(Size, Align)>> {
582 if !layout.is_unsized() {
583 return Ok(Some((layout.size, layout.align.abi)));
585 match layout.ty.kind() {
586 ty::Adt(..) | ty::Tuple(..) => {
587 // First get the size of all statically known fields.
588 // Don't use type_of::sizing_type_of because that expects t to be sized,
589 // and it also rounds up to alignment, which we want to avoid,
590 // as the unsized field's alignment could be smaller.
591 assert!(!layout.ty.is_simd());
592 assert!(layout.fields.count() > 0);
593 trace!("DST layout: {:?}", layout);
595 let sized_size = layout.fields.offset(layout.fields.count() - 1);
596 let sized_align = layout.align.abi;
598 "DST {} statically sized prefix size: {:?} align: {:?}",
604 // Recurse to get the size of the dynamically sized field (must be
605 // the last field). Can't have foreign types here, how would we
606 // adjust alignment and size for them?
607 let field = layout.field(self, layout.fields.count() - 1)?;
608 let (unsized_size, unsized_align) =
609 match self.size_and_align_of(metadata, &field)? {
610 Some(size_and_align) => size_and_align,
612 // A field with extern type. If this field is at offset 0, we behave
613 // like the underlying extern type.
614 // FIXME: Once we have made decisions for how to handle size and alignment
615 // of `extern type`, this should be adapted. It is just a temporary hack
616 // to get some code to work that probably ought to work.
617 if sized_size == Size::ZERO {
622 "Fields cannot be extern types, unless they are at offset 0"
628 // FIXME (#26403, #27023): We should be adding padding
629 // to `sized_size` (to accommodate the `unsized_align`
630 // required of the unsized field that follows) before
631 // summing it with `sized_size`. (Note that since #26403
632 // is unfixed, we do not yet add the necessary padding
633 // here. But this is where the add would go.)
635 // Return the sum of sizes and max of aligns.
636 let size = sized_size + unsized_size; // `Size` addition
638 // Choose max of two known alignments (combined value must
639 // be aligned according to more restrictive of the two).
640 let align = sized_align.max(unsized_align);
642 // Issue #27023: must add any necessary padding to `size`
643 // (to make it a multiple of `align`) before returning it.
644 let size = size.align_to(align);
646 // Check if this brought us over the size limit.
647 if size.bytes() >= self.tcx.data_layout.obj_size_bound() {
648 throw_ub!(InvalidMeta("total size is bigger than largest supported object"));
650 Ok(Some((size, align)))
653 let vtable = self.scalar_to_ptr(metadata.unwrap_meta());
654 // Read size and align from vtable (already checks size).
655 Ok(Some(self.read_size_and_align_from_vtable(vtable)?))
658 ty::Slice(_) | ty::Str => {
659 let len = metadata.unwrap_meta().to_machine_usize(self)?;
660 let elem = layout.field(self, 0)?;
662 // Make sure the slice is not too big.
663 let size = elem.size.checked_mul(len, self).ok_or_else(|| {
664 err_ub!(InvalidMeta("slice is bigger than largest supported object"))
666 Ok(Some((size, elem.align.abi)))
669 ty::Foreign(_) => Ok(None),
671 _ => span_bug!(self.cur_span(), "size_and_align_of::<{:?}> not supported", layout.ty),
675 pub fn size_and_align_of_mplace(
677 mplace: &MPlaceTy<'tcx, M::PointerTag>,
678 ) -> InterpResult<'tcx, Option<(Size, Align)>> {
679 self.size_and_align_of(&mplace.meta, &mplace.layout)
682 pub fn push_stack_frame(
684 instance: ty::Instance<'tcx>,
685 body: &'mir mir::Body<'tcx>,
686 return_place: Option<&PlaceTy<'tcx, M::PointerTag>>,
687 return_to_block: StackPopCleanup,
688 ) -> InterpResult<'tcx> {
689 // first push a stack frame so we have access to the local substs
690 let pre_frame = Frame {
692 loc: Err(body.span), // Span used for errors caused during preamble.
694 return_place: return_place.copied(),
695 // empty local array, we fill it in below, after we are inside the stack frame and
696 // all methods actually know about the frame
697 locals: IndexVec::new(),
699 tracing_span: SpanGuard::new(),
702 let frame = M::init_frame_extra(self, pre_frame)?;
703 self.stack_mut().push(frame);
705 // Make sure all the constants required by this frame evaluate successfully (post-monomorphization check).
706 for const_ in &body.required_consts {
707 let span = const_.span;
709 self.subst_from_current_frame_and_normalize_erasing_regions(const_.literal);
710 self.mir_const_to_op(&const_, None).map_err(|err| {
711 // If there was an error, set the span of the current frame to this constant.
712 // Avoiding doing this when evaluation succeeds.
713 self.frame_mut().loc = Err(span);
718 // Locals are initially uninitialized.
719 let dummy = LocalState { value: LocalValue::Uninitialized, layout: Cell::new(None) };
720 let mut locals = IndexVec::from_elem(dummy, &body.local_decls);
722 // Now mark those locals as dead that we do not want to initialize
723 // Mark locals that use `Storage*` annotations as dead on function entry.
724 let always_live = AlwaysLiveLocals::new(self.body());
725 for local in locals.indices() {
726 if !always_live.contains(local) {
727 locals[local].value = LocalValue::Dead;
731 self.frame_mut().locals = locals;
732 M::after_stack_push(self)?;
733 self.frame_mut().loc = Ok(mir::Location::START);
735 let span = info_span!("frame", "{}", instance);
736 self.frame_mut().tracing_span.enter(span);
741 /// Jump to the given block.
743 pub fn go_to_block(&mut self, target: mir::BasicBlock) {
744 self.frame_mut().loc = Ok(mir::Location { block: target, statement_index: 0 });
747 /// *Return* to the given `target` basic block.
748 /// Do *not* use for unwinding! Use `unwind_to_block` instead.
750 /// If `target` is `None`, that indicates the function cannot return, so we raise UB.
751 pub fn return_to_block(&mut self, target: Option<mir::BasicBlock>) -> InterpResult<'tcx> {
752 if let Some(target) = target {
753 self.go_to_block(target);
756 throw_ub!(Unreachable)
760 /// *Unwind* to the given `target` basic block.
761 /// Do *not* use for returning! Use `return_to_block` instead.
763 /// If `target` is `StackPopUnwind::Skip`, that indicates the function does not need cleanup
764 /// during unwinding, and we will just keep propagating that upwards.
766 /// If `target` is `StackPopUnwind::NotAllowed`, that indicates the function does not allow
767 /// unwinding, and doing so is UB.
768 pub fn unwind_to_block(&mut self, target: StackPopUnwind) -> InterpResult<'tcx> {
769 self.frame_mut().loc = match target {
770 StackPopUnwind::Cleanup(block) => Ok(mir::Location { block, statement_index: 0 }),
771 StackPopUnwind::Skip => Err(self.frame_mut().body.span),
772 StackPopUnwind::NotAllowed => {
773 throw_ub_format!("unwinding past a stack frame that does not allow unwinding")
779 /// Pops the current frame from the stack, deallocating the
780 /// memory for allocated locals.
782 /// If `unwinding` is `false`, then we are performing a normal return
783 /// from a function. In this case, we jump back into the frame of the caller,
784 /// and continue execution as normal.
786 /// If `unwinding` is `true`, then we are in the middle of a panic,
787 /// and need to unwind this frame. In this case, we jump to the
788 /// `cleanup` block for the function, which is responsible for running
789 /// `Drop` impls for any locals that have been initialized at this point.
790 /// The cleanup block ends with a special `Resume` terminator, which will
791 /// cause us to continue unwinding.
792 pub(super) fn pop_stack_frame(&mut self, unwinding: bool) -> InterpResult<'tcx> {
794 "popping stack frame ({})",
795 if unwinding { "during unwinding" } else { "returning from function" }
798 // Sanity check `unwinding`.
801 match self.frame().loc {
802 Ok(loc) => self.body().basic_blocks()[loc.block].is_cleanup,
807 if unwinding && self.frame_idx() == 0 {
808 throw_ub_format!("unwinding past the topmost frame of the stack");
812 self.stack_mut().pop().expect("tried to pop a stack frame, but there were none");
815 // Copy the return value to the caller's stack frame.
816 if let Some(ref return_place) = frame.return_place {
817 let op = self.access_local(&frame, mir::RETURN_PLACE, None)?;
818 self.copy_op_transmute(&op, return_place)?;
819 trace!("{:?}", self.dump_place(**return_place));
821 throw_ub!(Unreachable);
825 let return_to_block = frame.return_to_block;
827 // Now where do we jump next?
829 // Usually we want to clean up (deallocate locals), but in a few rare cases we don't.
830 // In that case, we return early. We also avoid validation in that case,
831 // because this is CTFE and the final value will be thoroughly validated anyway.
832 let cleanup = match return_to_block {
833 StackPopCleanup::Goto { .. } => true,
834 StackPopCleanup::None { cleanup, .. } => cleanup,
838 assert!(self.stack().is_empty(), "only the topmost frame should ever be leaked");
839 assert!(!unwinding, "tried to skip cleanup during unwinding");
840 // Leak the locals, skip validation, skip machine hook.
844 // Cleanup: deallocate all locals that are backed by an allocation.
845 for local in &frame.locals {
846 self.deallocate_local(local.value)?;
849 if M::after_stack_pop(self, frame, unwinding)? == StackPopJump::NoJump {
850 // The hook already did everything.
851 // We want to skip the `info!` below, hence early return.
854 // Normal return, figure out where to jump.
856 // Follow the unwind edge.
857 let unwind = match return_to_block {
858 StackPopCleanup::Goto { unwind, .. } => unwind,
859 StackPopCleanup::None { .. } => {
860 panic!("Encountered StackPopCleanup::None when unwinding!")
863 self.unwind_to_block(unwind)
865 // Follow the normal return edge.
866 match return_to_block {
867 StackPopCleanup::Goto { ret, .. } => self.return_to_block(ret),
868 StackPopCleanup::None { .. } => Ok(()),
873 /// Mark a storage as live, killing the previous content.
874 pub fn storage_live(&mut self, local: mir::Local) -> InterpResult<'tcx> {
875 assert!(local != mir::RETURN_PLACE, "Cannot make return place live");
876 trace!("{:?} is now live", local);
878 let local_val = LocalValue::Uninitialized;
879 // StorageLive expects the local to be dead, and marks it live.
880 let old = mem::replace(&mut self.frame_mut().locals[local].value, local_val);
881 if !matches!(old, LocalValue::Dead) {
882 throw_ub_format!("StorageLive on a local that was already live");
887 pub fn storage_dead(&mut self, local: mir::Local) -> InterpResult<'tcx> {
888 assert!(local != mir::RETURN_PLACE, "Cannot make return place dead");
889 trace!("{:?} is now dead", local);
891 // It is entirely okay for this local to be already dead (at least that's how we currently generate MIR)
892 let old = mem::replace(&mut self.frame_mut().locals[local].value, LocalValue::Dead);
893 self.deallocate_local(old)?;
897 fn deallocate_local(&mut self, local: LocalValue<M::PointerTag>) -> InterpResult<'tcx> {
898 if let LocalValue::Live(Operand::Indirect(MemPlace { ptr, .. })) = local {
899 // All locals have a backing allocation, even if the allocation is empty
900 // due to the local having ZST type.
902 "deallocating local {:?}: {:?}",
904 self.memory.dump_alloc(ptr.provenance.unwrap().erase_for_fmt())
906 self.memory.deallocate(ptr, None, MemoryKind::Stack)?;
911 pub fn eval_to_allocation(
914 ) -> InterpResult<'tcx, MPlaceTy<'tcx, M::PointerTag>> {
915 // For statics we pick `ParamEnv::reveal_all`, because statics don't have generics
916 // and thus don't care about the parameter environment. While we could just use
917 // `self.param_env`, that would mean we invoke the query to evaluate the static
918 // with different parameter environments, thus causing the static to be evaluated
920 let param_env = if self.tcx.is_static(gid.instance.def_id()) {
921 ty::ParamEnv::reveal_all()
925 let val = self.tcx.eval_to_allocation_raw(param_env.and(gid))?;
926 self.raw_const_to_mplace(val)
930 pub fn dump_place(&'a self, place: Place<M::PointerTag>) -> PlacePrinter<'a, 'mir, 'tcx, M> {
931 PlacePrinter { ecx: self, place }
935 pub fn generate_stacktrace(&self) -> Vec<FrameInfo<'tcx>> {
936 let mut frames = Vec::new();
941 .skip_while(|frame| frame.instance.def.requires_caller_location(*self.tcx))
943 let lint_root = frame.current_source_info().and_then(|source_info| {
944 match &frame.body.source_scopes[source_info.scope].local_data {
945 mir::ClearCrossCrate::Set(data) => Some(data.lint_root),
946 mir::ClearCrossCrate::Clear => None,
949 let span = frame.current_span();
951 frames.push(FrameInfo { span, instance: frame.instance, lint_root });
953 trace!("generate stacktrace: {:#?}", frames);
959 /// Helper struct for the `dump_place` function.
960 pub struct PlacePrinter<'a, 'mir, 'tcx, M: Machine<'mir, 'tcx>> {
961 ecx: &'a InterpCx<'mir, 'tcx, M>,
962 place: Place<M::PointerTag>,
965 impl<'a, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> std::fmt::Debug
966 for PlacePrinter<'a, 'mir, 'tcx, M>
968 fn fmt(&self, fmt: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
970 Place::Local { frame, local } => {
971 let mut allocs = Vec::new();
972 write!(fmt, "{:?}", local)?;
973 if frame != self.ecx.frame_idx() {
974 write!(fmt, " ({} frames up)", self.ecx.frame_idx() - frame)?;
978 match self.ecx.stack()[frame].locals[local].value {
979 LocalValue::Dead => write!(fmt, " is dead")?,
980 LocalValue::Uninitialized => write!(fmt, " is uninitialized")?,
981 LocalValue::Live(Operand::Indirect(mplace)) => {
984 " by align({}){} ref {:?}:",
985 mplace.align.bytes(),
987 MemPlaceMeta::Meta(meta) => format!(" meta({:?})", meta),
988 MemPlaceMeta::Poison | MemPlaceMeta::None => String::new(),
992 allocs.extend(mplace.ptr.map_erase_for_fmt().provenance);
994 LocalValue::Live(Operand::Immediate(Immediate::Scalar(val))) => {
995 write!(fmt, " {:?}", val)?;
996 if let ScalarMaybeUninit::Scalar(Scalar::Ptr(ptr)) = val {
997 allocs.push(ptr.provenance.erase_for_fmt());
1000 LocalValue::Live(Operand::Immediate(Immediate::ScalarPair(val1, val2))) => {
1001 write!(fmt, " ({:?}, {:?})", val1, val2)?;
1002 if let ScalarMaybeUninit::Scalar(Scalar::Ptr(ptr)) = val1 {
1003 allocs.push(ptr.provenance.erase_for_fmt());
1005 if let ScalarMaybeUninit::Scalar(Scalar::Ptr(ptr)) = val2 {
1006 allocs.push(ptr.provenance.erase_for_fmt());
1011 write!(fmt, ": {:?}", self.ecx.memory.dump_allocs(allocs))
1013 Place::Ptr(mplace) => match mplace.ptr.map_erase_for_fmt().provenance {
1014 Some(alloc_id) => write!(
1016 "by align({}) ref {:?}: {:?}",
1017 mplace.align.bytes(),
1019 self.ecx.memory.dump_alloc(alloc_id)
1021 ptr => write!(fmt, " integral by ref: {:?}", ptr),
1027 impl<'ctx, 'mir, 'tcx, Tag, Extra> HashStable<StableHashingContext<'ctx>>
1028 for Frame<'mir, 'tcx, Tag, Extra>
1030 Extra: HashStable<StableHashingContext<'ctx>>,
1031 Tag: HashStable<StableHashingContext<'ctx>>,
1033 fn hash_stable(&self, hcx: &mut StableHashingContext<'ctx>, hasher: &mut StableHasher) {
1034 // Exhaustive match on fields to make sure we forget no field.
1045 body.hash_stable(hcx, hasher);
1046 instance.hash_stable(hcx, hasher);
1047 return_to_block.hash_stable(hcx, hasher);
1048 return_place.as_ref().map(|r| &**r).hash_stable(hcx, hasher);
1049 locals.hash_stable(hcx, hasher);
1050 loc.hash_stable(hcx, hasher);
1051 extra.hash_stable(hcx, hasher);