5 use rustc_data_structures
::fx
::FxHashMap
;
6 use rustc_data_structures
::stable_hasher
::{HashStable, StableHasher}
;
7 use rustc_hir
::{self as hir, def::DefKind, def_id::DefId, definitions::DefPathData}
;
8 use rustc_index
::vec
::IndexVec
;
9 use rustc_macros
::HashStable
;
10 use rustc_middle
::ich
::StableHashingContext
;
11 use rustc_middle
::mir
;
12 use rustc_middle
::mir
::interpret
::{GlobalId, InterpResult, Pointer, Scalar}
;
13 use rustc_middle
::ty
::layout
::{self, TyAndLayout}
;
14 use rustc_middle
::ty
::{
15 self, query
::TyCtxtAt
, subst
::SubstsRef
, ParamEnv
, Ty
, TyCtxt
, TypeFoldable
,
17 use rustc_span
::{Pos, Span}
;
18 use rustc_target
::abi
::{Align, HasDataLayout, LayoutOf, Size, TargetDataLayout}
;
21 Immediate
, MPlaceTy
, Machine
, MemPlace
, MemPlaceMeta
, Memory
, Operand
, Place
, PlaceTy
,
22 ScalarMaybeUninit
, StackPopJump
,
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 /// A cache for deduplicating vtables
46 FxHashMap
<(Ty
<'tcx
>, Option
<ty
::PolyExistentialTraitRef
<'tcx
>>), Pointer
<M
::PointerTag
>>,
49 // The Phantomdata exists to prevent this type from being `Send`. If it were sent across a thread
50 // boundary and dropped in the other thread, it would exit the span in the other thread.
51 struct SpanGuard(tracing
::Span
, std
::marker
::PhantomData
<*const u8>);
54 /// By default a `SpanGuard` does nothing.
56 Self(tracing
::Span
::none(), std
::marker
::PhantomData
)
59 /// If a span is entered, we exit the previous span (if any, normally none) and enter the
60 /// new span. This is mainly so we don't have to use `Option` for the `tracing_span` field of
61 /// `Frame` by creating a dummy span to being with and then entering it once the frame has
63 fn enter(&mut self, span
: tracing
::Span
) {
64 // This executes the destructor on the previous instance of `SpanGuard`, ensuring that
65 // we never enter or exit more spans than vice versa. Unless you `mem::leak`, then we
66 // can't protect the tracing stack, but that'll just lead to weird logging, no actual
68 *self = Self(span
, std
::marker
::PhantomData
);
69 self.0.with_subscriber(|(id
, dispatch
)| {
75 impl Drop
for SpanGuard
{
77 self.0.with_subscriber(|(id
, dispatch
)| {
84 pub struct Frame
<'mir
, 'tcx
, Tag
= (), Extra
= ()> {
85 ////////////////////////////////////////////////////////////////////////////////
86 // Function and callsite information
87 ////////////////////////////////////////////////////////////////////////////////
88 /// The MIR for the function called on this frame.
89 pub body
: &'mir mir
::Body
<'tcx
>,
91 /// The def_id and substs of the current function.
92 pub instance
: ty
::Instance
<'tcx
>,
94 /// Extra data for the machine.
97 ////////////////////////////////////////////////////////////////////////////////
98 // Return place and locals
99 ////////////////////////////////////////////////////////////////////////////////
100 /// Work to perform when returning from this function.
101 pub return_to_block
: StackPopCleanup
,
103 /// The location where the result of the current stack frame should be written to,
104 /// and its layout in the caller.
105 pub return_place
: Option
<PlaceTy
<'tcx
, Tag
>>,
107 /// The list of locals for this stack frame, stored in order as
108 /// `[return_ptr, arguments..., variables..., temporaries...]`.
109 /// The locals are stored as `Option<Value>`s.
110 /// `None` represents a local that is currently dead, while a live local
111 /// can either directly contain `Scalar` or refer to some part of an `Allocation`.
112 pub locals
: IndexVec
<mir
::Local
, LocalState
<'tcx
, Tag
>>,
114 /// The span of the `tracing` crate is stored here.
115 /// When the guard is dropped, the span is exited. This gives us
116 /// a full stack trace on all tracing statements.
117 tracing_span
: SpanGuard
,
119 ////////////////////////////////////////////////////////////////////////////////
120 // Current position within the function
121 ////////////////////////////////////////////////////////////////////////////////
122 /// If this is `Err`, we are not currently executing any particular statement in
123 /// this frame (can happen e.g. during frame initialization, and during unwinding on
124 /// frames without cleanup code).
125 /// We basically abuse `Result` as `Either`.
126 pub(super) loc
: Result
<mir
::Location
, Span
>,
129 /// What we store about a frame in an interpreter backtrace.
131 pub struct FrameInfo
<'tcx
> {
132 pub instance
: ty
::Instance
<'tcx
>,
134 pub lint_root
: Option
<hir
::HirId
>,
137 #[derive(Clone, Eq, PartialEq, Debug, HashStable)] // Miri debug-prints these
138 pub enum StackPopCleanup
{
139 /// Jump to the next block in the caller, or cause UB if None (that's a function
140 /// that may never return). Also store layout of return place so
141 /// we can validate it at that layout.
142 /// `ret` stores the block we jump to on a normal return, while `unwind`
143 /// stores the block used for cleanup during unwinding.
144 Goto { ret: Option<mir::BasicBlock>, unwind: Option<mir::BasicBlock> }
,
145 /// Just do nothing: Used by Main and for the `box_alloc` hook in miri.
146 /// `cleanup` says whether locals are deallocated. Static computation
147 /// wants them leaked to intern what they need (and just throw away
148 /// the entire `ecx` when it is done).
149 None { cleanup: bool }
,
152 /// State of a local variable including a memoized layout
153 #[derive(Clone, PartialEq, Eq, HashStable)]
154 pub struct LocalState
<'tcx
, Tag
= ()> {
155 pub value
: LocalValue
<Tag
>,
156 /// Don't modify if `Some`, this is only used to prevent computing the layout twice
157 #[stable_hasher(ignore)]
158 pub layout
: Cell
<Option
<TyAndLayout
<'tcx
>>>,
161 /// Current value of a local variable
162 #[derive(Copy, Clone, PartialEq, Eq, Debug, HashStable)] // Miri debug-prints these
163 pub enum LocalValue
<Tag
= ()> {
164 /// This local is not currently alive, and cannot be used at all.
166 /// This local is alive but not yet initialized. It can be written to
167 /// but not read from or its address taken. Locals get initialized on
168 /// first write because for unsized locals, we do not know their size
171 /// A normal, live local.
172 /// Mostly for convenience, we re-use the `Operand` type here.
173 /// This is an optimization over just always having a pointer here;
174 /// we can thus avoid doing an allocation when the local just stores
175 /// immediate values *and* never has its address taken.
179 impl<'tcx
, Tag
: Copy
+ '
static> LocalState
<'tcx
, Tag
> {
180 /// Read the local's value or error if the local is not yet live or not live anymore.
182 /// Note: This may only be invoked from the `Machine::access_local` hook and not from
183 /// anywhere else. You may be invalidating machine invariants if you do!
184 pub fn access(&self) -> InterpResult
<'tcx
, Operand
<Tag
>> {
186 LocalValue
::Dead
=> throw_ub
!(DeadLocal
),
187 LocalValue
::Uninitialized
=> {
188 bug
!("The type checker should prevent reading from a never-written local")
190 LocalValue
::Live(val
) => Ok(val
),
194 /// Overwrite the local. If the local can be overwritten in place, return a reference
195 /// to do so; otherwise return the `MemPlace` to consult instead.
197 /// Note: This may only be invoked from the `Machine::access_local_mut` hook and not from
198 /// anywhere else. You may be invalidating machine invariants if you do!
201 ) -> InterpResult
<'tcx
, Result
<&mut LocalValue
<Tag
>, MemPlace
<Tag
>>> {
203 LocalValue
::Dead
=> throw_ub
!(DeadLocal
),
204 LocalValue
::Live(Operand
::Indirect(mplace
)) => Ok(Err(mplace
)),
206 local @
(LocalValue
::Live(Operand
::Immediate(_
)) | LocalValue
::Uninitialized
) => {
213 impl<'mir
, 'tcx
, Tag
> Frame
<'mir
, 'tcx
, Tag
> {
214 pub fn with_extra
<Extra
>(self, extra
: Extra
) -> Frame
<'mir
, 'tcx
, Tag
, Extra
> {
217 instance
: self.instance
,
218 return_to_block
: self.return_to_block
,
219 return_place
: self.return_place
,
223 tracing_span
: self.tracing_span
,
228 impl<'mir
, 'tcx
, Tag
, Extra
> Frame
<'mir
, 'tcx
, Tag
, Extra
> {
229 /// Return the `SourceInfo` of the current instruction.
230 pub fn current_source_info(&self) -> Option
<&mir
::SourceInfo
> {
231 self.loc
.ok().map(|loc
| self.body
.source_info(loc
))
234 pub fn current_span(&self) -> Span
{
236 Ok(loc
) => self.body
.source_info(loc
).span
,
242 impl<'tcx
> fmt
::Display
for FrameInfo
<'tcx
> {
243 fn fmt(&self, f
: &mut fmt
::Formatter
<'_
>) -> fmt
::Result
{
244 ty
::tls
::with(|tcx
| {
245 if tcx
.def_key(self.instance
.def_id()).disambiguated_data
.data
246 == DefPathData
::ClosureExpr
248 write
!(f
, "inside closure")?
;
250 write
!(f
, "inside `{}`", self.instance
)?
;
252 if !self.span
.is_dummy() {
253 let lo
= tcx
.sess
.source_map().lookup_char_pos(self.span
.lo());
254 write
!(f
, " at {}:{}:{}", lo
.file
.name
, lo
.line
, lo
.col
.to_usize() + 1)?
;
261 impl<'mir
, 'tcx
, M
: Machine
<'mir
, 'tcx
>> HasDataLayout
for InterpCx
<'mir
, 'tcx
, M
> {
263 fn data_layout(&self) -> &TargetDataLayout
{
264 &self.tcx
.data_layout
268 impl<'mir
, 'tcx
, M
> layout
::HasTyCtxt
<'tcx
> for InterpCx
<'mir
, 'tcx
, M
>
270 M
: Machine
<'mir
, 'tcx
>,
273 fn tcx(&self) -> TyCtxt
<'tcx
> {
278 impl<'mir
, 'tcx
, M
> layout
::HasParamEnv
<'tcx
> for InterpCx
<'mir
, 'tcx
, M
>
280 M
: Machine
<'mir
, 'tcx
>,
282 fn param_env(&self) -> ty
::ParamEnv
<'tcx
> {
287 impl<'mir
, 'tcx
: 'mir
, M
: Machine
<'mir
, 'tcx
>> LayoutOf
for InterpCx
<'mir
, 'tcx
, M
> {
289 type TyAndLayout
= InterpResult
<'tcx
, TyAndLayout
<'tcx
>>;
292 fn layout_of(&self, ty
: Ty
<'tcx
>) -> Self::TyAndLayout
{
294 .layout_of(self.param_env
.and(ty
))
295 .map_err(|layout
| err_inval
!(Layout(layout
)).into())
299 /// Test if it is valid for a MIR assignment to assign `src`-typed place to `dest`-typed value.
300 /// This test should be symmetric, as it is primarily about layout compatibility.
301 pub(super) fn mir_assign_valid_types
<'tcx
>(
303 param_env
: ParamEnv
<'tcx
>,
304 src
: TyAndLayout
<'tcx
>,
305 dest
: TyAndLayout
<'tcx
>,
307 // Type-changing assignments can happen when subtyping is used. While
308 // all normal lifetimes are erased, higher-ranked types with their
309 // late-bound lifetimes are still around and can lead to type
310 // differences. So we compare ignoring lifetimes.
311 if equal_up_to_regions(tcx
, param_env
, src
.ty
, dest
.ty
) {
312 // Make sure the layout is equal, too -- just to be safe. Miri really
313 // needs layout equality. For performance reason we skip this check when
314 // the types are equal. Equal types *can* have different layouts when
315 // enum downcast is involved (as enum variants carry the type of the
316 // enum), but those should never occur in assignments.
317 if cfg
!(debug_assertions
) || src
.ty
!= dest
.ty
{
318 assert_eq
!(src
.layout
, dest
.layout
);
326 /// Use the already known layout if given (but sanity check in debug mode),
327 /// or compute the layout.
328 #[cfg_attr(not(debug_assertions), inline(always))]
329 pub(super) fn from_known_layout
<'tcx
>(
331 param_env
: ParamEnv
<'tcx
>,
332 known_layout
: Option
<TyAndLayout
<'tcx
>>,
333 compute
: impl FnOnce() -> InterpResult
<'tcx
, TyAndLayout
<'tcx
>>,
334 ) -> InterpResult
<'tcx
, TyAndLayout
<'tcx
>> {
337 Some(known_layout
) => {
338 if cfg
!(debug_assertions
) {
339 let check_layout
= compute()?
;
340 if !mir_assign_valid_types(tcx
.tcx
, param_env
, check_layout
, known_layout
) {
343 "expected type differs from actual type.\nexpected: {:?}\nactual: {:?}",
354 impl<'mir
, 'tcx
: 'mir
, M
: Machine
<'mir
, 'tcx
>> InterpCx
<'mir
, 'tcx
, M
> {
358 param_env
: ty
::ParamEnv
<'tcx
>,
360 memory_extra
: M
::MemoryExtra
,
364 tcx
: tcx
.at(root_span
),
366 memory
: Memory
::new(tcx
, memory_extra
),
367 vtables
: FxHashMap
::default(),
372 pub fn cur_span(&self) -> Span
{
373 self.stack().last().map(|f
| f
.current_span()).unwrap_or(self.tcx
.span
)
379 scalar
: Scalar
<M
::PointerTag
>,
380 ) -> InterpResult
<'tcx
, Pointer
<M
::PointerTag
>> {
381 self.memory
.force_ptr(scalar
)
387 scalar
: Scalar
<M
::PointerTag
>,
389 ) -> InterpResult
<'tcx
, u128
> {
390 self.memory
.force_bits(scalar
, size
)
393 /// Call this to turn untagged "global" pointers (obtained via `tcx`) into
394 /// the machine pointer to the allocation. Must never be used
395 /// for any other pointers, nor for TLS statics.
397 /// Using the resulting pointer represents a *direct* access to that memory
398 /// (e.g. by directly using a `static`),
399 /// as opposed to access through a pointer that was created by the program.
401 /// This function can fail only if `ptr` points to an `extern static`.
403 pub fn global_base_pointer(&self, ptr
: Pointer
) -> InterpResult
<'tcx
, Pointer
<M
::PointerTag
>> {
404 self.memory
.global_base_pointer(ptr
)
408 pub(crate) fn stack(&self) -> &[Frame
<'mir
, 'tcx
, M
::PointerTag
, M
::FrameExtra
>] {
413 pub(crate) fn stack_mut(
415 ) -> &mut Vec
<Frame
<'mir
, 'tcx
, M
::PointerTag
, M
::FrameExtra
>> {
420 pub fn frame_idx(&self) -> usize {
421 let stack
= self.stack();
422 assert
!(!stack
.is_empty());
427 pub fn frame(&self) -> &Frame
<'mir
, 'tcx
, M
::PointerTag
, M
::FrameExtra
> {
428 self.stack().last().expect("no call frames exist")
432 pub fn frame_mut(&mut self) -> &mut Frame
<'mir
, 'tcx
, M
::PointerTag
, M
::FrameExtra
> {
433 self.stack_mut().last_mut().expect("no call frames exist")
437 pub(super) fn body(&self) -> &'mir mir
::Body
<'tcx
> {
442 pub fn sign_extend(&self, value
: u128
, ty
: TyAndLayout
<'_
>) -> u128
{
443 assert
!(ty
.abi
.is_signed());
444 ty
.size
.sign_extend(value
)
448 pub fn truncate(&self, value
: u128
, ty
: TyAndLayout
<'_
>) -> u128
{
449 ty
.size
.truncate(value
)
453 pub fn type_is_sized(&self, ty
: Ty
<'tcx
>) -> bool
{
454 ty
.is_sized(self.tcx
, self.param_env
)
458 pub fn type_is_freeze(&self, ty
: Ty
<'tcx
>) -> bool
{
459 ty
.is_freeze(self.tcx
, self.param_env
)
464 instance
: ty
::InstanceDef
<'tcx
>,
465 promoted
: Option
<mir
::Promoted
>,
466 ) -> InterpResult
<'tcx
, &'tcx mir
::Body
<'tcx
>> {
467 // do not continue if typeck errors occurred (can only occur in local crate)
468 let def
= instance
.with_opt_param();
469 if let Some(def
) = def
.as_local() {
470 if self.tcx
.has_typeck_results(def
.did
) {
471 if let Some(error_reported
) = self.tcx
.typeck_opt_const_arg(def
).tainted_by_errors
{
472 throw_inval
!(AlreadyReported(error_reported
))
476 trace
!("load mir(instance={:?}, promoted={:?})", instance
, promoted
);
477 if let Some(promoted
) = promoted
{
478 return Ok(&self.tcx
.promoted_mir_opt_const_arg(def
)[promoted
]);
481 ty
::InstanceDef
::Item(def
) => {
482 if self.tcx
.is_mir_available(def
.did
) {
483 Ok(self.tcx
.optimized_mir_opt_const_arg(def
))
485 throw_unsup
!(NoMirFor(def
.did
))
488 _
=> Ok(self.tcx
.instance_mir(instance
)),
492 /// Call this on things you got out of the MIR (so it is as generic as the current
493 /// stack frame), to bring it into the proper environment for this interpreter.
494 pub(super) fn subst_from_current_frame_and_normalize_erasing_regions
<T
: TypeFoldable
<'tcx
>>(
498 self.subst_from_frame_and_normalize_erasing_regions(self.frame(), value
)
501 /// Call this on things you got out of the MIR (so it is as generic as the provided
502 /// stack frame), to bring it into the proper environment for this interpreter.
503 pub(super) fn subst_from_frame_and_normalize_erasing_regions
<T
: TypeFoldable
<'tcx
>>(
505 frame
: &Frame
<'mir
, 'tcx
, M
::PointerTag
, M
::FrameExtra
>,
508 frame
.instance
.subst_mir_and_normalize_erasing_regions(*self.tcx
, self.param_env
, &value
)
511 /// The `substs` are assumed to already be in our interpreter "universe" (param_env).
512 pub(super) fn resolve(
514 def
: ty
::WithOptConstParam
<DefId
>,
515 substs
: SubstsRef
<'tcx
>,
516 ) -> InterpResult
<'tcx
, ty
::Instance
<'tcx
>> {
517 trace
!("resolve: {:?}, {:#?}", def
, substs
);
518 trace
!("param_env: {:#?}", self.param_env
);
519 trace
!("substs: {:#?}", substs
);
520 match ty
::Instance
::resolve_opt_const_arg(*self.tcx
, self.param_env
, def
, substs
) {
521 Ok(Some(instance
)) => Ok(instance
),
522 Ok(None
) => throw_inval
!(TooGeneric
),
524 // FIXME(eddyb) this could be a bit more specific than `AlreadyReported`.
525 Err(error_reported
) => throw_inval
!(AlreadyReported(error_reported
)),
529 pub fn layout_of_local(
531 frame
: &Frame
<'mir
, 'tcx
, M
::PointerTag
, M
::FrameExtra
>,
533 layout
: Option
<TyAndLayout
<'tcx
>>,
534 ) -> InterpResult
<'tcx
, TyAndLayout
<'tcx
>> {
535 // `const_prop` runs into this with an invalid (empty) frame, so we
536 // have to support that case (mostly by skipping all caching).
537 match frame
.locals
.get(local
).and_then(|state
| state
.layout
.get()) {
539 let layout
= from_known_layout(self.tcx
, self.param_env
, layout
, || {
540 let local_ty
= frame
.body
.local_decls
[local
].ty
;
542 self.subst_from_frame_and_normalize_erasing_regions(frame
, local_ty
);
543 self.layout_of(local_ty
)
545 if let Some(state
) = frame
.locals
.get(local
) {
546 // Layouts of locals are requested a lot, so we cache them.
547 state
.layout
.set(Some(layout
));
551 Some(layout
) => Ok(layout
),
555 /// Returns the actual dynamic size and alignment of the place at the given type.
556 /// Only the "meta" (metadata) part of the place matters.
557 /// This can fail to provide an answer for extern types.
558 pub(super) fn size_and_align_of(
560 metadata
: MemPlaceMeta
<M
::PointerTag
>,
561 layout
: TyAndLayout
<'tcx
>,
562 ) -> InterpResult
<'tcx
, Option
<(Size
, Align
)>> {
563 if !layout
.is_unsized() {
564 return Ok(Some((layout
.size
, layout
.align
.abi
)));
566 match layout
.ty
.kind() {
567 ty
::Adt(..) | ty
::Tuple(..) => {
568 // First get the size of all statically known fields.
569 // Don't use type_of::sizing_type_of because that expects t to be sized,
570 // and it also rounds up to alignment, which we want to avoid,
571 // as the unsized field's alignment could be smaller.
572 assert
!(!layout
.ty
.is_simd());
573 assert
!(layout
.fields
.count() > 0);
574 trace
!("DST layout: {:?}", layout
);
576 let sized_size
= layout
.fields
.offset(layout
.fields
.count() - 1);
577 let sized_align
= layout
.align
.abi
;
579 "DST {} statically sized prefix size: {:?} align: {:?}",
585 // Recurse to get the size of the dynamically sized field (must be
586 // the last field). Can't have foreign types here, how would we
587 // adjust alignment and size for them?
588 let field
= layout
.field(self, layout
.fields
.count() - 1)?
;
589 let (unsized_size
, unsized_align
) = match self.size_and_align_of(metadata
, field
)?
{
590 Some(size_and_align
) => size_and_align
,
592 // A field with extern type. If this field is at offset 0, we behave
593 // like the underlying extern type.
594 // FIXME: Once we have made decisions for how to handle size and alignment
595 // of `extern type`, this should be adapted. It is just a temporary hack
596 // to get some code to work that probably ought to work.
597 if sized_size
== Size
::ZERO
{
602 "Fields cannot be extern types, unless they are at offset 0"
608 // FIXME (#26403, #27023): We should be adding padding
609 // to `sized_size` (to accommodate the `unsized_align`
610 // required of the unsized field that follows) before
611 // summing it with `sized_size`. (Note that since #26403
612 // is unfixed, we do not yet add the necessary padding
613 // here. But this is where the add would go.)
615 // Return the sum of sizes and max of aligns.
616 let size
= sized_size
+ unsized_size
; // `Size` addition
618 // Choose max of two known alignments (combined value must
619 // be aligned according to more restrictive of the two).
620 let align
= sized_align
.max(unsized_align
);
622 // Issue #27023: must add any necessary padding to `size`
623 // (to make it a multiple of `align`) before returning it.
624 let size
= size
.align_to(align
);
626 // Check if this brought us over the size limit.
627 if size
.bytes() >= self.tcx
.data_layout
.obj_size_bound() {
628 throw_ub
!(InvalidMeta("total size is bigger than largest supported object"));
630 Ok(Some((size
, align
)))
633 let vtable
= metadata
.unwrap_meta();
634 // Read size and align from vtable (already checks size).
635 Ok(Some(self.read_size_and_align_from_vtable(vtable
)?
))
638 ty
::Slice(_
) | ty
::Str
=> {
639 let len
= metadata
.unwrap_meta().to_machine_usize(self)?
;
640 let elem
= layout
.field(self, 0)?
;
642 // Make sure the slice is not too big.
643 let size
= elem
.size
.checked_mul(len
, self).ok_or_else(|| {
644 err_ub
!(InvalidMeta("slice is bigger than largest supported object"))
646 Ok(Some((size
, elem
.align
.abi
)))
649 ty
::Foreign(_
) => Ok(None
),
651 _
=> span_bug
!(self.cur_span(), "size_and_align_of::<{:?}> not supported", layout
.ty
),
655 pub fn size_and_align_of_mplace(
657 mplace
: MPlaceTy
<'tcx
, M
::PointerTag
>,
658 ) -> InterpResult
<'tcx
, Option
<(Size
, Align
)>> {
659 self.size_and_align_of(mplace
.meta
, mplace
.layout
)
662 pub fn push_stack_frame(
664 instance
: ty
::Instance
<'tcx
>,
665 body
: &'mir mir
::Body
<'tcx
>,
666 return_place
: Option
<PlaceTy
<'tcx
, M
::PointerTag
>>,
667 return_to_block
: StackPopCleanup
,
668 ) -> InterpResult
<'tcx
> {
669 // first push a stack frame so we have access to the local substs
670 let pre_frame
= Frame
{
672 loc
: Err(body
.span
), // Span used for errors caused during preamble.
675 // empty local array, we fill it in below, after we are inside the stack frame and
676 // all methods actually know about the frame
677 locals
: IndexVec
::new(),
679 tracing_span
: SpanGuard
::new(),
682 let frame
= M
::init_frame_extra(self, pre_frame
)?
;
683 self.stack_mut().push(frame
);
685 // Make sure all the constants required by this frame evaluate successfully (post-monomorphization check).
686 for const_
in &body
.required_consts
{
687 let span
= const_
.span
;
689 self.subst_from_current_frame_and_normalize_erasing_regions(const_
.literal
);
690 self.const_to_op(const_
, None
).map_err(|err
| {
691 // If there was an error, set the span of the current frame to this constant.
692 // Avoiding doing this when evaluation succeeds.
693 self.frame_mut().loc
= Err(span
);
698 // Locals are initially uninitialized.
699 let dummy
= LocalState { value: LocalValue::Uninitialized, layout: Cell::new(None) }
;
700 let mut locals
= IndexVec
::from_elem(dummy
, &body
.local_decls
);
702 // Now mark those locals as dead that we do not want to initialize
703 match self.tcx
.def_kind(instance
.def_id()) {
704 // statics and constants don't have `Storage*` statements, no need to look for them
706 // FIXME: The above is likely untrue. See
707 // <https://github.com/rust-lang/rust/pull/70004#issuecomment-602022110>. Is it
708 // okay to ignore `StorageDead`/`StorageLive` annotations during CTFE?
709 DefKind
::Static
| DefKind
::Const
| DefKind
::AssocConst
=> {}
711 // Mark locals that use `Storage*` annotations as dead on function entry.
712 let always_live
= AlwaysLiveLocals
::new(self.body());
713 for local
in locals
.indices() {
714 if !always_live
.contains(local
) {
715 locals
[local
].value
= LocalValue
::Dead
;
721 self.frame_mut().locals
= locals
;
722 M
::after_stack_push(self)?
;
723 self.frame_mut().loc
= Ok(mir
::Location
::START
);
725 let span
= info_span
!("frame", "{}", instance
);
726 self.frame_mut().tracing_span
.enter(span
);
731 /// Jump to the given block.
733 pub fn go_to_block(&mut self, target
: mir
::BasicBlock
) {
734 self.frame_mut().loc
= Ok(mir
::Location { block: target, statement_index: 0 }
);
737 /// *Return* to the given `target` basic block.
738 /// Do *not* use for unwinding! Use `unwind_to_block` instead.
740 /// If `target` is `None`, that indicates the function cannot return, so we raise UB.
741 pub fn return_to_block(&mut self, target
: Option
<mir
::BasicBlock
>) -> InterpResult
<'tcx
> {
742 if let Some(target
) = target
{
743 self.go_to_block(target
);
746 throw_ub
!(Unreachable
)
750 /// *Unwind* to the given `target` basic block.
751 /// Do *not* use for returning! Use `return_to_block` instead.
753 /// If `target` is `None`, that indicates the function does not need cleanup during
754 /// unwinding, and we will just keep propagating that upwards.
755 pub fn unwind_to_block(&mut self, target
: Option
<mir
::BasicBlock
>) {
756 self.frame_mut().loc
= match target
{
757 Some(block
) => Ok(mir
::Location { block, statement_index: 0 }
),
758 None
=> Err(self.frame_mut().body
.span
),
762 /// Pops the current frame from the stack, deallocating the
763 /// memory for allocated locals.
765 /// If `unwinding` is `false`, then we are performing a normal return
766 /// from a function. In this case, we jump back into the frame of the caller,
767 /// and continue execution as normal.
769 /// If `unwinding` is `true`, then we are in the middle of a panic,
770 /// and need to unwind this frame. In this case, we jump to the
771 /// `cleanup` block for the function, which is responsible for running
772 /// `Drop` impls for any locals that have been initialized at this point.
773 /// The cleanup block ends with a special `Resume` terminator, which will
774 /// cause us to continue unwinding.
775 pub(super) fn pop_stack_frame(&mut self, unwinding
: bool
) -> InterpResult
<'tcx
> {
777 "popping stack frame ({})",
778 if unwinding { "during unwinding" }
else { "returning from function" }
781 // Sanity check `unwinding`.
784 match self.frame().loc
{
785 Ok(loc
) => self.body().basic_blocks()[loc
.block
].is_cleanup
,
790 if unwinding
&& self.frame_idx() == 0 {
791 throw_ub_format
!("unwinding past the topmost frame of the stack");
795 self.stack_mut().pop().expect("tried to pop a stack frame, but there were none");
798 // Copy the return value to the caller's stack frame.
799 if let Some(return_place
) = frame
.return_place
{
800 let op
= self.access_local(&frame
, mir
::RETURN_PLACE
, None
)?
;
801 self.copy_op_transmute(op
, return_place
)?
;
802 trace
!("{:?}", self.dump_place(*return_place
));
804 throw_ub
!(Unreachable
);
808 // Now where do we jump next?
810 // Usually we want to clean up (deallocate locals), but in a few rare cases we don't.
811 // In that case, we return early. We also avoid validation in that case,
812 // because this is CTFE and the final value will be thoroughly validated anyway.
813 let (cleanup
, next_block
) = match frame
.return_to_block
{
814 StackPopCleanup
::Goto { ret, unwind }
=> {
815 (true, Some(if unwinding { unwind }
else { ret }
))
817 StackPopCleanup
::None { cleanup, .. }
=> (cleanup
, None
),
821 assert
!(self.stack().is_empty(), "only the topmost frame should ever be leaked");
822 assert
!(next_block
.is_none(), "tried to skip cleanup when we have a next block!");
823 assert
!(!unwinding
, "tried to skip cleanup during unwinding");
824 // Leak the locals, skip validation, skip machine hook.
828 // Cleanup: deallocate all locals that are backed by an allocation.
829 for local
in &frame
.locals
{
830 self.deallocate_local(local
.value
)?
;
833 if M
::after_stack_pop(self, frame
, unwinding
)?
== StackPopJump
::NoJump
{
834 // The hook already did everything.
835 // We want to skip the `info!` below, hence early return.
838 // Normal return, figure out where to jump.
840 // Follow the unwind edge.
841 let unwind
= next_block
.expect("Encountered StackPopCleanup::None when unwinding!");
842 self.unwind_to_block(unwind
);
844 // Follow the normal return edge.
845 if let Some(ret
) = next_block
{
846 self.return_to_block(ret
)?
;
853 /// Mark a storage as live, killing the previous content and returning it.
854 /// Remember to deallocate that!
858 ) -> InterpResult
<'tcx
, LocalValue
<M
::PointerTag
>> {
859 assert
!(local
!= mir
::RETURN_PLACE
, "Cannot make return place live");
860 trace
!("{:?} is now live", local
);
862 let local_val
= LocalValue
::Uninitialized
;
863 // StorageLive *always* kills the value that's currently stored.
864 // However, we do not error if the variable already is live;
865 // see <https://github.com/rust-lang/rust/issues/42371>.
866 Ok(mem
::replace(&mut self.frame_mut().locals
[local
].value
, local_val
))
869 /// Returns the old value of the local.
870 /// Remember to deallocate that!
871 pub fn storage_dead(&mut self, local
: mir
::Local
) -> LocalValue
<M
::PointerTag
> {
872 assert
!(local
!= mir
::RETURN_PLACE
, "Cannot make return place dead");
873 trace
!("{:?} is now dead", local
);
875 mem
::replace(&mut self.frame_mut().locals
[local
].value
, LocalValue
::Dead
)
878 pub(super) fn deallocate_local(
880 local
: LocalValue
<M
::PointerTag
>,
881 ) -> InterpResult
<'tcx
> {
882 // FIXME: should we tell the user that there was a local which was never written to?
883 if let LocalValue
::Live(Operand
::Indirect(MemPlace { ptr, .. }
)) = local
{
884 // All locals have a backing allocation, even if the allocation is empty
885 // due to the local having ZST type.
886 let ptr
= ptr
.assert_ptr();
887 trace
!("deallocating local: {:?}", self.memory
.dump_alloc(ptr
.alloc_id
));
888 self.memory
.deallocate_local(ptr
)?
;
893 pub fn eval_to_allocation(
896 ) -> InterpResult
<'tcx
, MPlaceTy
<'tcx
, M
::PointerTag
>> {
897 // For statics we pick `ParamEnv::reveal_all`, because statics don't have generics
898 // and thus don't care about the parameter environment. While we could just use
899 // `self.param_env`, that would mean we invoke the query to evaluate the static
900 // with different parameter environments, thus causing the static to be evaluated
902 let param_env
= if self.tcx
.is_static(gid
.instance
.def_id()) {
903 ty
::ParamEnv
::reveal_all()
907 let val
= self.tcx
.eval_to_allocation_raw(param_env
.and(gid
))?
;
908 self.raw_const_to_mplace(val
)
912 pub fn dump_place(&'a
self, place
: Place
<M
::PointerTag
>) -> PlacePrinter
<'a
, 'mir
, 'tcx
, M
> {
913 PlacePrinter { ecx: self, place }
917 pub fn generate_stacktrace(&self) -> Vec
<FrameInfo
<'tcx
>> {
918 let mut frames
= Vec
::new();
919 for frame
in self.stack().iter().rev() {
920 let lint_root
= frame
.current_source_info().and_then(|source_info
| {
921 match &frame
.body
.source_scopes
[source_info
.scope
].local_data
{
922 mir
::ClearCrossCrate
::Set(data
) => Some(data
.lint_root
),
923 mir
::ClearCrossCrate
::Clear
=> None
,
926 let span
= frame
.current_span();
928 frames
.push(FrameInfo { span, instance: frame.instance, lint_root }
);
930 trace
!("generate stacktrace: {:#?}", frames
);
936 /// Helper struct for the `dump_place` function.
937 pub struct PlacePrinter
<'a
, 'mir
, 'tcx
, M
: Machine
<'mir
, 'tcx
>> {
938 ecx
: &'a InterpCx
<'mir
, 'tcx
, M
>,
939 place
: Place
<M
::PointerTag
>,
942 impl<'a
, 'mir
, 'tcx
: 'mir
, M
: Machine
<'mir
, 'tcx
>> std
::fmt
::Debug
943 for PlacePrinter
<'a
, 'mir
, 'tcx
, M
>
945 fn fmt(&self, fmt
: &mut std
::fmt
::Formatter
<'_
>) -> std
::fmt
::Result
{
947 Place
::Local { frame, local }
=> {
948 let mut allocs
= Vec
::new();
949 write
!(fmt
, "{:?}", local
)?
;
950 if frame
!= self.ecx
.frame_idx() {
951 write
!(fmt
, " ({} frames up)", self.ecx
.frame_idx() - frame
)?
;
955 match self.ecx
.stack()[frame
].locals
[local
].value
{
956 LocalValue
::Dead
=> write
!(fmt
, " is dead")?
,
957 LocalValue
::Uninitialized
=> write
!(fmt
, " is uninitialized")?
,
958 LocalValue
::Live(Operand
::Indirect(mplace
)) => match mplace
.ptr
{
959 Scalar
::Ptr(ptr
) => {
962 " by align({}){} ref:",
963 mplace
.align
.bytes(),
965 MemPlaceMeta
::Meta(meta
) => format
!(" meta({:?})", meta
),
966 MemPlaceMeta
::Poison
| MemPlaceMeta
::None
=> String
::new(),
969 allocs
.push(ptr
.alloc_id
);
971 ptr
=> write
!(fmt
, " by integral ref: {:?}", ptr
)?
,
973 LocalValue
::Live(Operand
::Immediate(Immediate
::Scalar(val
))) => {
974 write
!(fmt
, " {:?}", val
)?
;
975 if let ScalarMaybeUninit
::Scalar(Scalar
::Ptr(ptr
)) = val
{
976 allocs
.push(ptr
.alloc_id
);
979 LocalValue
::Live(Operand
::Immediate(Immediate
::ScalarPair(val1
, val2
))) => {
980 write
!(fmt
, " ({:?}, {:?})", val1
, val2
)?
;
981 if let ScalarMaybeUninit
::Scalar(Scalar
::Ptr(ptr
)) = val1
{
982 allocs
.push(ptr
.alloc_id
);
984 if let ScalarMaybeUninit
::Scalar(Scalar
::Ptr(ptr
)) = val2
{
985 allocs
.push(ptr
.alloc_id
);
990 write
!(fmt
, ": {:?}", self.ecx
.memory
.dump_allocs(allocs
))
992 Place
::Ptr(mplace
) => match mplace
.ptr
{
993 Scalar
::Ptr(ptr
) => write
!(
995 "by align({}) ref: {:?}",
996 mplace
.align
.bytes(),
997 self.ecx
.memory
.dump_alloc(ptr
.alloc_id
)
999 ptr
=> write
!(fmt
, " integral by ref: {:?}", ptr
),
1005 impl<'ctx
, 'mir
, 'tcx
, Tag
, Extra
> HashStable
<StableHashingContext
<'ctx
>>
1006 for Frame
<'mir
, 'tcx
, Tag
, Extra
>
1008 Extra
: HashStable
<StableHashingContext
<'ctx
>>,
1009 Tag
: HashStable
<StableHashingContext
<'ctx
>>,
1011 fn hash_stable(&self, hcx
: &mut StableHashingContext
<'ctx
>, hasher
: &mut StableHasher
) {
1012 // Exhaustive match on fields to make sure we forget no field.
1023 body
.hash_stable(hcx
, hasher
);
1024 instance
.hash_stable(hcx
, hasher
);
1025 return_to_block
.hash_stable(hcx
, hasher
);
1026 return_place
.as_ref().map(|r
| &**r
).hash_stable(hcx
, hasher
);
1027 locals
.hash_stable(hcx
, hasher
);
1028 loc
.hash_stable(hcx
, hasher
);
1029 extra
.hash_stable(hcx
, hasher
);