miri/
machine.rs

1//! Global machine state as well as implementation of the interpreter engine
2//! `Machine` trait.
3
4use std::any::Any;
5use std::borrow::Cow;
6use std::cell::{Cell, RefCell};
7use std::collections::hash_map::Entry;
8use std::path::Path;
9use std::rc::Rc;
10use std::{fmt, process};
11
12use rand::rngs::StdRng;
13use rand::{Rng, SeedableRng};
14use rustc_abi::{Align, ExternAbi, Size};
15use rustc_apfloat::{Float, FloatConvert};
16use rustc_attr_data_structures::InlineAttr;
17use rustc_data_structures::fx::{FxHashMap, FxHashSet};
18#[allow(unused)]
19use rustc_data_structures::static_assert_size;
20use rustc_middle::mir;
21use rustc_middle::query::TyCtxtAt;
22use rustc_middle::ty::layout::{
23    HasTyCtxt, HasTypingEnv, LayoutCx, LayoutError, LayoutOf, TyAndLayout,
24};
25use rustc_middle::ty::{self, Instance, Ty, TyCtxt};
26use rustc_session::config::InliningThreshold;
27use rustc_span::def_id::{CrateNum, DefId};
28use rustc_span::{Span, SpanData, Symbol};
29use rustc_target::callconv::FnAbi;
30
31use crate::alloc_addresses::EvalContextExt;
32use crate::concurrency::cpu_affinity::{self, CpuAffinityMask};
33use crate::concurrency::data_race::{self, NaReadType, NaWriteType};
34use crate::concurrency::{AllocDataRaceHandler, GenmcCtx, GlobalDataRaceHandler, weak_memory};
35use crate::*;
36
37/// First real-time signal.
38/// `signal(7)` says this must be between 32 and 64 and specifies 34 or 35
39/// as typical values.
40pub const SIGRTMIN: i32 = 34;
41
42/// Last real-time signal.
43/// `signal(7)` says it must be between 32 and 64 and specifies
44/// `SIGRTMAX` - `SIGRTMIN` >= 8 (which is the value of `_POSIX_RTSIG_MAX`)
45pub const SIGRTMAX: i32 = 42;
46
47/// Each anonymous global (constant, vtable, function pointer, ...) has multiple addresses, but only
48/// this many. Since const allocations are never deallocated, choosing a new [`AllocId`] and thus
49/// base address for each evaluation would produce unbounded memory usage.
50const ADDRS_PER_ANON_GLOBAL: usize = 32;
51
52/// Extra data stored with each stack frame
53pub struct FrameExtra<'tcx> {
54    /// Extra data for the Borrow Tracker.
55    pub borrow_tracker: Option<borrow_tracker::FrameState>,
56
57    /// If this is Some(), then this is a special "catch unwind" frame (the frame of `try_fn`
58    /// called by `try`). When this frame is popped during unwinding a panic,
59    /// we stop unwinding, use the `CatchUnwindData` to handle catching.
60    pub catch_unwind: Option<CatchUnwindData<'tcx>>,
61
62    /// If `measureme` profiling is enabled, holds timing information
63    /// for the start of this frame. When we finish executing this frame,
64    /// we use this to register a completed event with `measureme`.
65    pub timing: Option<measureme::DetachedTiming>,
66
67    /// Indicates whether a `Frame` is part of a workspace-local crate and is also not
68    /// `#[track_caller]`. We compute this once on creation and store the result, as an
69    /// optimization.
70    /// This is used by `MiriMachine::current_span` and `MiriMachine::caller_span`
71    pub is_user_relevant: bool,
72
73    /// We have a cache for the mapping from [`mir::Const`] to resulting [`AllocId`].
74    /// However, we don't want all frames to always get the same result, so we insert
75    /// an additional bit of "salt" into the cache key. This salt is fixed per-frame
76    /// so that within a call, a const will have a stable address.
77    salt: usize,
78
79    /// Data race detector per-frame data.
80    pub data_race: Option<data_race::FrameState>,
81}
82
83impl<'tcx> std::fmt::Debug for FrameExtra<'tcx> {
84    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
85        // Omitting `timing`, it does not support `Debug`.
86        let FrameExtra {
87            borrow_tracker,
88            catch_unwind,
89            timing: _,
90            is_user_relevant,
91            salt,
92            data_race,
93        } = self;
94        f.debug_struct("FrameData")
95            .field("borrow_tracker", borrow_tracker)
96            .field("catch_unwind", catch_unwind)
97            .field("is_user_relevant", is_user_relevant)
98            .field("salt", salt)
99            .field("data_race", data_race)
100            .finish()
101    }
102}
103
104impl VisitProvenance for FrameExtra<'_> {
105    fn visit_provenance(&self, visit: &mut VisitWith<'_>) {
106        let FrameExtra {
107            catch_unwind,
108            borrow_tracker,
109            timing: _,
110            is_user_relevant: _,
111            salt: _,
112            data_race: _,
113        } = self;
114
115        catch_unwind.visit_provenance(visit);
116        borrow_tracker.visit_provenance(visit);
117    }
118}
119
120/// Extra memory kinds
121#[derive(Debug, Copy, Clone, PartialEq, Eq)]
122pub enum MiriMemoryKind {
123    /// `__rust_alloc` memory.
124    Rust,
125    /// `miri_alloc` memory.
126    Miri,
127    /// `malloc` memory.
128    C,
129    /// Windows `HeapAlloc` memory.
130    WinHeap,
131    /// Windows "local" memory (to be freed with `LocalFree`)
132    WinLocal,
133    /// Memory for args, errno, and other parts of the machine-managed environment.
134    /// This memory may leak.
135    Machine,
136    /// Memory allocated by the runtime (e.g. env vars). Separate from `Machine`
137    /// because we clean it up and leak-check it.
138    Runtime,
139    /// Globals copied from `tcx`.
140    /// This memory may leak.
141    Global,
142    /// Memory for extern statics.
143    /// This memory may leak.
144    ExternStatic,
145    /// Memory for thread-local statics.
146    /// This memory may leak.
147    Tls,
148    /// Memory mapped directly by the program
149    Mmap,
150}
151
152impl From<MiriMemoryKind> for MemoryKind {
153    #[inline(always)]
154    fn from(kind: MiriMemoryKind) -> MemoryKind {
155        MemoryKind::Machine(kind)
156    }
157}
158
159impl MayLeak for MiriMemoryKind {
160    #[inline(always)]
161    fn may_leak(self) -> bool {
162        use self::MiriMemoryKind::*;
163        match self {
164            Rust | Miri | C | WinHeap | WinLocal | Runtime => false,
165            Machine | Global | ExternStatic | Tls | Mmap => true,
166        }
167    }
168}
169
170impl MiriMemoryKind {
171    /// Whether we have a useful allocation span for an allocation of this kind.
172    fn should_save_allocation_span(self) -> bool {
173        use self::MiriMemoryKind::*;
174        match self {
175            // Heap allocations are fine since the `Allocation` is created immediately.
176            Rust | Miri | C | WinHeap | WinLocal | Mmap => true,
177            // Everything else is unclear, let's not show potentially confusing spans.
178            Machine | Global | ExternStatic | Tls | Runtime => false,
179        }
180    }
181}
182
183impl fmt::Display for MiriMemoryKind {
184    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
185        use self::MiriMemoryKind::*;
186        match self {
187            Rust => write!(f, "Rust heap"),
188            Miri => write!(f, "Miri bare-metal heap"),
189            C => write!(f, "C heap"),
190            WinHeap => write!(f, "Windows heap"),
191            WinLocal => write!(f, "Windows local memory"),
192            Machine => write!(f, "machine-managed memory"),
193            Runtime => write!(f, "language runtime memory"),
194            Global => write!(f, "global (static or const)"),
195            ExternStatic => write!(f, "extern static"),
196            Tls => write!(f, "thread-local static"),
197            Mmap => write!(f, "mmap"),
198        }
199    }
200}
201
202pub type MemoryKind = interpret::MemoryKind<MiriMemoryKind>;
203
204/// Pointer provenance.
205// This needs to be `Eq`+`Hash` because the `Machine` trait needs that because validity checking
206// *might* be recursive and then it has to track which places have already been visited.
207// These implementations are a bit questionable, and it means we may check the same place multiple
208// times with different provenance, but that is in general not wrong.
209#[derive(Clone, Copy, PartialEq, Eq, Hash)]
210pub enum Provenance {
211    /// For pointers with concrete provenance. we exactly know which allocation they are attached to
212    /// and what their borrow tag is.
213    Concrete {
214        alloc_id: AllocId,
215        /// Borrow Tracker tag.
216        tag: BorTag,
217    },
218    /// Pointers with wildcard provenance are created on int-to-ptr casts. According to the
219    /// specification, we should at that point angelically "guess" a provenance that will make all
220    /// future uses of this pointer work, if at all possible. Of course such a semantics cannot be
221    /// actually implemented in Miri. So instead, we approximate this, erroring on the side of
222    /// accepting too much code rather than rejecting correct code: a pointer with wildcard
223    /// provenance "acts like" any previously exposed pointer. Each time it is used, we check
224    /// whether *some* exposed pointer could have done what we want to do, and if the answer is yes
225    /// then we allow the access. This allows too much code in two ways:
226    /// - The same wildcard pointer can "take the role" of multiple different exposed pointers on
227    ///   subsequent memory accesses.
228    /// - In the aliasing model, we don't just have to know the borrow tag of the pointer used for
229    ///   the access, we also have to update the aliasing state -- and that update can be very
230    ///   different depending on which borrow tag we pick! Stacked Borrows has support for this by
231    ///   switching to a stack that is only approximately known, i.e. we over-approximate the effect
232    ///   of using *any* exposed pointer for this access, and only keep information about the borrow
233    ///   stack that would be true with all possible choices.
234    Wildcard,
235}
236
237/// The "extra" information a pointer has over a regular AllocId.
238#[derive(Copy, Clone, PartialEq)]
239pub enum ProvenanceExtra {
240    Concrete(BorTag),
241    Wildcard,
242}
243
244#[cfg(target_pointer_width = "64")]
245static_assert_size!(StrictPointer, 24);
246// FIXME: this would with in 24bytes but layout optimizations are not smart enough
247// #[cfg(target_pointer_width = "64")]
248//static_assert_size!(Pointer, 24);
249#[cfg(target_pointer_width = "64")]
250static_assert_size!(Scalar, 32);
251
252impl fmt::Debug for Provenance {
253    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
254        match self {
255            Provenance::Concrete { alloc_id, tag } => {
256                // Forward `alternate` flag to `alloc_id` printing.
257                if f.alternate() {
258                    write!(f, "[{alloc_id:#?}]")?;
259                } else {
260                    write!(f, "[{alloc_id:?}]")?;
261                }
262                // Print Borrow Tracker tag.
263                write!(f, "{tag:?}")?;
264            }
265            Provenance::Wildcard => {
266                write!(f, "[wildcard]")?;
267            }
268        }
269        Ok(())
270    }
271}
272
273impl interpret::Provenance for Provenance {
274    /// We use absolute addresses in the `offset` of a `StrictPointer`.
275    const OFFSET_IS_ADDR: bool = true;
276
277    /// Miri implements wildcard provenance.
278    const WILDCARD: Option<Self> = Some(Provenance::Wildcard);
279
280    fn get_alloc_id(self) -> Option<AllocId> {
281        match self {
282            Provenance::Concrete { alloc_id, .. } => Some(alloc_id),
283            Provenance::Wildcard => None,
284        }
285    }
286
287    fn fmt(ptr: &interpret::Pointer<Self>, f: &mut fmt::Formatter<'_>) -> fmt::Result {
288        let (prov, addr) = ptr.into_parts(); // address is absolute
289        write!(f, "{:#x}", addr.bytes())?;
290        if f.alternate() {
291            write!(f, "{prov:#?}")?;
292        } else {
293            write!(f, "{prov:?}")?;
294        }
295        Ok(())
296    }
297
298    fn join(left: Option<Self>, right: Option<Self>) -> Option<Self> {
299        match (left, right) {
300            // If both are the *same* concrete tag, that is the result.
301            (
302                Some(Provenance::Concrete { alloc_id: left_alloc, tag: left_tag }),
303                Some(Provenance::Concrete { alloc_id: right_alloc, tag: right_tag }),
304            ) if left_alloc == right_alloc && left_tag == right_tag => left,
305            // If one side is a wildcard, the best possible outcome is that it is equal to the other
306            // one, and we use that.
307            (Some(Provenance::Wildcard), o) | (o, Some(Provenance::Wildcard)) => o,
308            // Otherwise, fall back to `None`.
309            _ => None,
310        }
311    }
312}
313
314impl fmt::Debug for ProvenanceExtra {
315    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
316        match self {
317            ProvenanceExtra::Concrete(pid) => write!(f, "{pid:?}"),
318            ProvenanceExtra::Wildcard => write!(f, "<wildcard>"),
319        }
320    }
321}
322
323impl ProvenanceExtra {
324    pub fn and_then<T>(self, f: impl FnOnce(BorTag) -> Option<T>) -> Option<T> {
325        match self {
326            ProvenanceExtra::Concrete(pid) => f(pid),
327            ProvenanceExtra::Wildcard => None,
328        }
329    }
330}
331
332/// Extra per-allocation data
333#[derive(Debug)]
334pub struct AllocExtra<'tcx> {
335    /// Global state of the borrow tracker, if enabled.
336    pub borrow_tracker: Option<borrow_tracker::AllocState>,
337    /// Extra state for data race detection.
338    ///
339    /// Invariant: The enum variant must match the enum variant in the `data_race` field on `MiriMachine`
340    pub data_race: AllocDataRaceHandler,
341    /// A backtrace to where this allocation was allocated.
342    /// As this is recorded for leak reports, it only exists
343    /// if this allocation is leakable. The backtrace is not
344    /// pruned yet; that should be done before printing it.
345    pub backtrace: Option<Vec<FrameInfo<'tcx>>>,
346    /// Synchronization primitives like to attach extra data to particular addresses. We store that
347    /// inside the relevant allocation, to ensure that everything is removed when the allocation is
348    /// freed.
349    /// This maps offsets to synchronization-primitive-specific data.
350    pub sync: FxHashMap<Size, Box<dyn Any>>,
351}
352
353// We need a `Clone` impl because the machine passes `Allocation` through `Cow`...
354// but that should never end up actually cloning our `AllocExtra`.
355impl<'tcx> Clone for AllocExtra<'tcx> {
356    fn clone(&self) -> Self {
357        panic!("our allocations should never be cloned");
358    }
359}
360
361impl VisitProvenance for AllocExtra<'_> {
362    fn visit_provenance(&self, visit: &mut VisitWith<'_>) {
363        let AllocExtra { borrow_tracker, data_race, backtrace: _, sync: _ } = self;
364
365        borrow_tracker.visit_provenance(visit);
366        data_race.visit_provenance(visit);
367    }
368}
369
370/// Precomputed layouts of primitive types
371pub struct PrimitiveLayouts<'tcx> {
372    pub unit: TyAndLayout<'tcx>,
373    pub i8: TyAndLayout<'tcx>,
374    pub i16: TyAndLayout<'tcx>,
375    pub i32: TyAndLayout<'tcx>,
376    pub i64: TyAndLayout<'tcx>,
377    pub i128: TyAndLayout<'tcx>,
378    pub isize: TyAndLayout<'tcx>,
379    pub u8: TyAndLayout<'tcx>,
380    pub u16: TyAndLayout<'tcx>,
381    pub u32: TyAndLayout<'tcx>,
382    pub u64: TyAndLayout<'tcx>,
383    pub u128: TyAndLayout<'tcx>,
384    pub usize: TyAndLayout<'tcx>,
385    pub bool: TyAndLayout<'tcx>,
386    pub mut_raw_ptr: TyAndLayout<'tcx>,   // *mut ()
387    pub const_raw_ptr: TyAndLayout<'tcx>, // *const ()
388}
389
390impl<'tcx> PrimitiveLayouts<'tcx> {
391    fn new(layout_cx: LayoutCx<'tcx>) -> Result<Self, &'tcx LayoutError<'tcx>> {
392        let tcx = layout_cx.tcx();
393        let mut_raw_ptr = Ty::new_mut_ptr(tcx, tcx.types.unit);
394        let const_raw_ptr = Ty::new_imm_ptr(tcx, tcx.types.unit);
395        Ok(Self {
396            unit: layout_cx.layout_of(tcx.types.unit)?,
397            i8: layout_cx.layout_of(tcx.types.i8)?,
398            i16: layout_cx.layout_of(tcx.types.i16)?,
399            i32: layout_cx.layout_of(tcx.types.i32)?,
400            i64: layout_cx.layout_of(tcx.types.i64)?,
401            i128: layout_cx.layout_of(tcx.types.i128)?,
402            isize: layout_cx.layout_of(tcx.types.isize)?,
403            u8: layout_cx.layout_of(tcx.types.u8)?,
404            u16: layout_cx.layout_of(tcx.types.u16)?,
405            u32: layout_cx.layout_of(tcx.types.u32)?,
406            u64: layout_cx.layout_of(tcx.types.u64)?,
407            u128: layout_cx.layout_of(tcx.types.u128)?,
408            usize: layout_cx.layout_of(tcx.types.usize)?,
409            bool: layout_cx.layout_of(tcx.types.bool)?,
410            mut_raw_ptr: layout_cx.layout_of(mut_raw_ptr)?,
411            const_raw_ptr: layout_cx.layout_of(const_raw_ptr)?,
412        })
413    }
414
415    pub fn uint(&self, size: Size) -> Option<TyAndLayout<'tcx>> {
416        match size.bits() {
417            8 => Some(self.u8),
418            16 => Some(self.u16),
419            32 => Some(self.u32),
420            64 => Some(self.u64),
421            128 => Some(self.u128),
422            _ => None,
423        }
424    }
425
426    pub fn int(&self, size: Size) -> Option<TyAndLayout<'tcx>> {
427        match size.bits() {
428            8 => Some(self.i8),
429            16 => Some(self.i16),
430            32 => Some(self.i32),
431            64 => Some(self.i64),
432            128 => Some(self.i128),
433            _ => None,
434        }
435    }
436}
437
438/// The machine itself.
439///
440/// If you add anything here that stores machine values, remember to update
441/// `visit_all_machine_values`!
442pub struct MiriMachine<'tcx> {
443    // We carry a copy of the global `TyCtxt` for convenience, so methods taking just `&Evaluator` have `tcx` access.
444    pub tcx: TyCtxt<'tcx>,
445
446    /// Global data for borrow tracking.
447    pub borrow_tracker: Option<borrow_tracker::GlobalState>,
448
449    /// Depending on settings, this will be `None`,
450    /// global data for a data race detector,
451    /// or the context required for running in GenMC mode.
452    ///
453    /// Invariant: The enum variant must match the enum variant of `AllocDataRaceHandler` in the `data_race` field of all `AllocExtra`.
454    pub data_race: GlobalDataRaceHandler,
455
456    /// Ptr-int-cast module global data.
457    pub alloc_addresses: alloc_addresses::GlobalState,
458
459    /// Environment variables.
460    pub(crate) env_vars: EnvVars<'tcx>,
461
462    /// Return place of the main function.
463    pub(crate) main_fn_ret_place: Option<MPlaceTy<'tcx>>,
464
465    /// Program arguments (`Option` because we can only initialize them after creating the ecx).
466    /// These are *pointers* to argc/argv because macOS.
467    /// We also need the full command line as one string because of Windows.
468    pub(crate) argc: Option<Pointer>,
469    pub(crate) argv: Option<Pointer>,
470    pub(crate) cmd_line: Option<Pointer>,
471
472    /// TLS state.
473    pub(crate) tls: TlsData<'tcx>,
474
475    /// What should Miri do when an op requires communicating with the host,
476    /// such as accessing host env vars, random number generation, and
477    /// file system access.
478    pub(crate) isolated_op: IsolatedOp,
479
480    /// Whether to enforce the validity invariant.
481    pub(crate) validation: ValidationMode,
482
483    /// The table of file descriptors.
484    pub(crate) fds: shims::FdTable,
485    /// The table of directory descriptors.
486    pub(crate) dirs: shims::DirTable,
487
488    /// The list of all EpollEventInterest.
489    pub(crate) epoll_interests: shims::EpollInterestTable,
490
491    /// This machine's monotone clock.
492    pub(crate) monotonic_clock: MonotonicClock,
493
494    /// The set of threads.
495    pub(crate) threads: ThreadManager<'tcx>,
496
497    /// Stores which thread is eligible to run on which CPUs.
498    /// This has no effect at all, it is just tracked to produce the correct result
499    /// in `sched_getaffinity`
500    pub(crate) thread_cpu_affinity: FxHashMap<ThreadId, CpuAffinityMask>,
501
502    /// The state of the primitive synchronization objects.
503    pub(crate) sync: SynchronizationObjects,
504
505    /// Precomputed `TyLayout`s for primitive data types that are commonly used inside Miri.
506    pub(crate) layouts: PrimitiveLayouts<'tcx>,
507
508    /// Allocations that are considered roots of static memory (that may leak).
509    pub(crate) static_roots: Vec<AllocId>,
510
511    /// The `measureme` profiler used to record timing information about
512    /// the emulated program.
513    profiler: Option<measureme::Profiler>,
514    /// Used with `profiler` to cache the `StringId`s for event names
515    /// used with `measureme`.
516    string_cache: FxHashMap<String, measureme::StringId>,
517
518    /// Cache of `Instance` exported under the given `Symbol` name.
519    /// `None` means no `Instance` exported under the given name is found.
520    pub(crate) exported_symbols_cache: FxHashMap<Symbol, Option<Instance<'tcx>>>,
521
522    /// Equivalent setting as RUST_BACKTRACE on encountering an error.
523    pub(crate) backtrace_style: BacktraceStyle,
524
525    /// Crates which are considered local for the purposes of error reporting.
526    pub(crate) local_crates: Vec<CrateNum>,
527
528    /// Mapping extern static names to their pointer.
529    extern_statics: FxHashMap<Symbol, StrictPointer>,
530
531    /// The random number generator used for resolving non-determinism.
532    /// Needs to be queried by ptr_to_int, hence needs interior mutability.
533    pub(crate) rng: RefCell<StdRng>,
534
535    /// The allocation IDs to report when they are being allocated
536    /// (helps for debugging memory leaks and use after free bugs).
537    tracked_alloc_ids: FxHashSet<AllocId>,
538    /// For the tracked alloc ids, also report read/write accesses.
539    track_alloc_accesses: bool,
540
541    /// Controls whether alignment of memory accesses is being checked.
542    pub(crate) check_alignment: AlignmentCheck,
543
544    /// Failure rate of compare_exchange_weak, between 0.0 and 1.0
545    pub(crate) cmpxchg_weak_failure_rate: f64,
546
547    /// The probability of the active thread being preempted at the end of each basic block.
548    pub(crate) preemption_rate: f64,
549
550    /// If `Some`, we will report the current stack every N basic blocks.
551    pub(crate) report_progress: Option<u32>,
552    // The total number of blocks that have been executed.
553    pub(crate) basic_block_count: u64,
554
555    /// Handle of the optional shared object file for native functions.
556    #[cfg(unix)]
557    pub native_lib: Option<(libloading::Library, std::path::PathBuf)>,
558    #[cfg(not(unix))]
559    pub native_lib: Option<!>,
560
561    /// Run a garbage collector for BorTags every N basic blocks.
562    pub(crate) gc_interval: u32,
563    /// The number of blocks that passed since the last BorTag GC pass.
564    pub(crate) since_gc: u32,
565
566    /// The number of CPUs to be reported by miri.
567    pub(crate) num_cpus: u32,
568
569    /// Determines Miri's page size and associated values
570    pub(crate) page_size: u64,
571    pub(crate) stack_addr: u64,
572    pub(crate) stack_size: u64,
573
574    /// Whether to collect a backtrace when each allocation is created, just in case it leaks.
575    pub(crate) collect_leak_backtraces: bool,
576
577    /// The spans we will use to report where an allocation was created and deallocated in
578    /// diagnostics.
579    pub(crate) allocation_spans: RefCell<FxHashMap<AllocId, (Span, Option<Span>)>>,
580
581    /// Maps MIR consts to their evaluated result. We combine the const with a "salt" (`usize`)
582    /// that is fixed per stack frame; this lets us have sometimes different results for the
583    /// same const while ensuring consistent results within a single call.
584    const_cache: RefCell<FxHashMap<(mir::Const<'tcx>, usize), OpTy<'tcx>>>,
585
586    /// For each allocation, an offset inside that allocation that was deemed aligned even for
587    /// symbolic alignment checks. This cannot be stored in `AllocExtra` since it needs to be
588    /// tracked for vtables and function allocations as well as regular allocations.
589    ///
590    /// Invariant: the promised alignment will never be less than the native alignment of the
591    /// allocation.
592    pub(crate) symbolic_alignment: RefCell<FxHashMap<AllocId, (Size, Align)>>,
593
594    /// A cache of "data range" computations for unions (i.e., the offsets of non-padding bytes).
595    union_data_ranges: FxHashMap<Ty<'tcx>, RangeSet>,
596
597    /// Caches the sanity-checks for various pthread primitives.
598    pub(crate) pthread_mutex_sanity: Cell<bool>,
599    pub(crate) pthread_rwlock_sanity: Cell<bool>,
600    pub(crate) pthread_condvar_sanity: Cell<bool>,
601
602    /// Remembers whether we already warned about an extern type with Stacked Borrows.
603    pub(crate) sb_extern_type_warned: Cell<bool>,
604    /// Remember whether we already warned about sharing memory with a native call.
605    #[cfg(unix)]
606    pub(crate) native_call_mem_warned: Cell<bool>,
607    /// Remembers which shims have already shown the warning about erroring in isolation.
608    pub(crate) reject_in_isolation_warned: RefCell<FxHashSet<String>>,
609    /// Remembers which int2ptr casts we have already warned about.
610    pub(crate) int2ptr_warned: RefCell<FxHashSet<Span>>,
611
612    /// Cache for `mangle_internal_symbol`.
613    pub(crate) mangle_internal_symbol_cache: FxHashMap<&'static str, String>,
614
615    /// Always prefer the intrinsic fallback body over the native Miri implementation.
616    pub force_intrinsic_fallback: bool,
617}
618
619impl<'tcx> MiriMachine<'tcx> {
620    pub(crate) fn new(
621        config: &MiriConfig,
622        layout_cx: LayoutCx<'tcx>,
623        genmc_ctx: Option<Rc<GenmcCtx>>,
624    ) -> Self {
625        let tcx = layout_cx.tcx();
626        let local_crates = helpers::get_local_crates(tcx);
627        let layouts =
628            PrimitiveLayouts::new(layout_cx).expect("Couldn't get layouts of primitive types");
629        let profiler = config.measureme_out.as_ref().map(|out| {
630            let crate_name =
631                tcx.sess.opts.crate_name.clone().unwrap_or_else(|| "unknown-crate".to_string());
632            let pid = process::id();
633            // We adopt the same naming scheme for the profiler output that rustc uses. In rustc,
634            // the PID is padded so that the nondeterministic value of the PID does not spread
635            // nondeterminism to the allocator. In Miri we are not aiming for such performance
636            // control, we just pad for consistency with rustc.
637            let filename = format!("{crate_name}-{pid:07}");
638            let path = Path::new(out).join(filename);
639            measureme::Profiler::new(path).expect("Couldn't create `measureme` profiler")
640        });
641        let rng = StdRng::seed_from_u64(config.seed.unwrap_or(0));
642        let borrow_tracker = config.borrow_tracker.map(|bt| bt.instantiate_global_state(config));
643        let data_race = if config.genmc_mode {
644            // `genmc_ctx` persists across executions, so we don't create a new one here.
645            GlobalDataRaceHandler::Genmc(genmc_ctx.unwrap())
646        } else if config.data_race_detector {
647            GlobalDataRaceHandler::Vclocks(Box::new(data_race::GlobalState::new(config)))
648        } else {
649            GlobalDataRaceHandler::None
650        };
651        // Determine page size, stack address, and stack size.
652        // These values are mostly meaningless, but the stack address is also where we start
653        // allocating physical integer addresses for all allocations.
654        let page_size = if let Some(page_size) = config.page_size {
655            page_size
656        } else {
657            let target = &tcx.sess.target;
658            match target.arch.as_ref() {
659                "wasm32" | "wasm64" => 64 * 1024, // https://webassembly.github.io/spec/core/exec/runtime.html#memory-instances
660                "aarch64" => {
661                    if target.options.vendor.as_ref() == "apple" {
662                        // No "definitive" source, but see:
663                        // https://www.wwdcnotes.com/notes/wwdc20/10214/
664                        // https://github.com/ziglang/zig/issues/11308 etc.
665                        16 * 1024
666                    } else {
667                        4 * 1024
668                    }
669                }
670                _ => 4 * 1024,
671            }
672        };
673        // On 16bit targets, 32 pages is more than the entire address space!
674        let stack_addr = if tcx.pointer_size().bits() < 32 { page_size } else { page_size * 32 };
675        let stack_size =
676            if tcx.pointer_size().bits() < 32 { page_size * 4 } else { page_size * 16 };
677        assert!(
678            usize::try_from(config.num_cpus).unwrap() <= cpu_affinity::MAX_CPUS,
679            "miri only supports up to {} CPUs, but {} were configured",
680            cpu_affinity::MAX_CPUS,
681            config.num_cpus
682        );
683        let threads = ThreadManager::new(config);
684        let mut thread_cpu_affinity = FxHashMap::default();
685        if matches!(&*tcx.sess.target.os, "linux" | "freebsd" | "android") {
686            thread_cpu_affinity
687                .insert(threads.active_thread(), CpuAffinityMask::new(&layout_cx, config.num_cpus));
688        }
689        MiriMachine {
690            tcx,
691            borrow_tracker,
692            data_race,
693            alloc_addresses: RefCell::new(alloc_addresses::GlobalStateInner::new(config, stack_addr)),
694            // `env_vars` depends on a full interpreter so we cannot properly initialize it yet.
695            env_vars: EnvVars::default(),
696            main_fn_ret_place: None,
697            argc: None,
698            argv: None,
699            cmd_line: None,
700            tls: TlsData::default(),
701            isolated_op: config.isolated_op,
702            validation: config.validation,
703            fds: shims::FdTable::init(config.mute_stdout_stderr),
704            epoll_interests: shims::EpollInterestTable::new(),
705            dirs: Default::default(),
706            layouts,
707            threads,
708            thread_cpu_affinity,
709            sync: SynchronizationObjects::default(),
710            static_roots: Vec::new(),
711            profiler,
712            string_cache: Default::default(),
713            exported_symbols_cache: FxHashMap::default(),
714            backtrace_style: config.backtrace_style,
715            local_crates,
716            extern_statics: FxHashMap::default(),
717            rng: RefCell::new(rng),
718            tracked_alloc_ids: config.tracked_alloc_ids.clone(),
719            track_alloc_accesses: config.track_alloc_accesses,
720            check_alignment: config.check_alignment,
721            cmpxchg_weak_failure_rate: config.cmpxchg_weak_failure_rate,
722            preemption_rate: config.preemption_rate,
723            report_progress: config.report_progress,
724            basic_block_count: 0,
725            monotonic_clock: MonotonicClock::new(config.isolated_op == IsolatedOp::Allow),
726            #[cfg(unix)]
727            native_lib: config.native_lib.as_ref().map(|lib_file_path| {
728                let host_triple = rustc_session::config::host_tuple();
729                let target_triple = tcx.sess.opts.target_triple.tuple();
730                // Check if host target == the session target.
731                if host_triple != target_triple {
732                    panic!(
733                        "calling native C functions in linked .so file requires host and target to be the same: \
734                        host={host_triple}, target={target_triple}",
735                    );
736                }
737                // Note: it is the user's responsibility to provide a correct SO file.
738                // WATCH OUT: If an invalid/incorrect SO file is specified, this can cause
739                // undefined behaviour in Miri itself!
740                (
741                    unsafe {
742                        libloading::Library::new(lib_file_path)
743                            .expect("failed to read specified extern shared object file")
744                    },
745                    lib_file_path.clone(),
746                )
747            }),
748            #[cfg(not(unix))]
749            native_lib: config.native_lib.as_ref().map(|_| {
750                panic!("calling functions from native libraries via FFI is only supported on Unix")
751            }),
752            gc_interval: config.gc_interval,
753            since_gc: 0,
754            num_cpus: config.num_cpus,
755            page_size,
756            stack_addr,
757            stack_size,
758            collect_leak_backtraces: config.collect_leak_backtraces,
759            allocation_spans: RefCell::new(FxHashMap::default()),
760            const_cache: RefCell::new(FxHashMap::default()),
761            symbolic_alignment: RefCell::new(FxHashMap::default()),
762            union_data_ranges: FxHashMap::default(),
763            pthread_mutex_sanity: Cell::new(false),
764            pthread_rwlock_sanity: Cell::new(false),
765            pthread_condvar_sanity: Cell::new(false),
766            sb_extern_type_warned: Cell::new(false),
767            #[cfg(unix)]
768            native_call_mem_warned: Cell::new(false),
769            reject_in_isolation_warned: Default::default(),
770            int2ptr_warned: Default::default(),
771            mangle_internal_symbol_cache: Default::default(),
772            force_intrinsic_fallback: config.force_intrinsic_fallback,
773        }
774    }
775
776    pub(crate) fn late_init(
777        ecx: &mut MiriInterpCx<'tcx>,
778        config: &MiriConfig,
779        on_main_stack_empty: StackEmptyCallback<'tcx>,
780    ) -> InterpResult<'tcx> {
781        EnvVars::init(ecx, config)?;
782        MiriMachine::init_extern_statics(ecx)?;
783        ThreadManager::init(ecx, on_main_stack_empty);
784        interp_ok(())
785    }
786
787    pub(crate) fn add_extern_static(ecx: &mut MiriInterpCx<'tcx>, name: &str, ptr: Pointer) {
788        // This got just allocated, so there definitely is a pointer here.
789        let ptr = ptr.into_pointer_or_addr().unwrap();
790        ecx.machine.extern_statics.try_insert(Symbol::intern(name), ptr).unwrap();
791    }
792
793    pub(crate) fn communicate(&self) -> bool {
794        self.isolated_op == IsolatedOp::Allow
795    }
796
797    /// Check whether the stack frame that this `FrameInfo` refers to is part of a local crate.
798    pub(crate) fn is_local(&self, frame: &FrameInfo<'_>) -> bool {
799        let def_id = frame.instance.def_id();
800        def_id.is_local() || self.local_crates.contains(&def_id.krate)
801    }
802
803    /// Called when the interpreter is going to shut down abnormally, such as due to a Ctrl-C.
804    pub(crate) fn handle_abnormal_termination(&mut self) {
805        // All strings in the profile data are stored in a single string table which is not
806        // written to disk until the profiler is dropped. If the interpreter exits without dropping
807        // the profiler, it is not possible to interpret the profile data and all measureme tools
808        // will panic when given the file.
809        drop(self.profiler.take());
810    }
811
812    pub(crate) fn page_align(&self) -> Align {
813        Align::from_bytes(self.page_size).unwrap()
814    }
815
816    pub(crate) fn allocated_span(&self, alloc_id: AllocId) -> Option<SpanData> {
817        self.allocation_spans
818            .borrow()
819            .get(&alloc_id)
820            .map(|(allocated, _deallocated)| allocated.data())
821    }
822
823    pub(crate) fn deallocated_span(&self, alloc_id: AllocId) -> Option<SpanData> {
824        self.allocation_spans
825            .borrow()
826            .get(&alloc_id)
827            .and_then(|(_allocated, deallocated)| *deallocated)
828            .map(Span::data)
829    }
830
831    fn init_allocation(
832        ecx: &MiriInterpCx<'tcx>,
833        id: AllocId,
834        kind: MemoryKind,
835        size: Size,
836        align: Align,
837    ) -> InterpResult<'tcx, AllocExtra<'tcx>> {
838        if ecx.machine.tracked_alloc_ids.contains(&id) {
839            ecx.emit_diagnostic(NonHaltingDiagnostic::CreatedAlloc(id, size, align, kind));
840        }
841
842        let borrow_tracker = ecx
843            .machine
844            .borrow_tracker
845            .as_ref()
846            .map(|bt| bt.borrow_mut().new_allocation(id, size, kind, &ecx.machine));
847
848        let data_race = match &ecx.machine.data_race {
849            GlobalDataRaceHandler::None => AllocDataRaceHandler::None,
850            GlobalDataRaceHandler::Vclocks(data_race) =>
851                AllocDataRaceHandler::Vclocks(
852                    data_race::AllocState::new_allocation(
853                        data_race,
854                        &ecx.machine.threads,
855                        size,
856                        kind,
857                        ecx.machine.current_span(),
858                    ),
859                    data_race.weak_memory.then(weak_memory::AllocState::new_allocation),
860                ),
861            GlobalDataRaceHandler::Genmc(_genmc_ctx) => {
862                // GenMC learns about new allocations directly from the alloc_addresses module,
863                // since it has to be able to control the address at which they are placed.
864                AllocDataRaceHandler::Genmc
865            }
866        };
867
868        // If an allocation is leaked, we want to report a backtrace to indicate where it was
869        // allocated. We don't need to record a backtrace for allocations which are allowed to
870        // leak.
871        let backtrace = if kind.may_leak() || !ecx.machine.collect_leak_backtraces {
872            None
873        } else {
874            Some(ecx.generate_stacktrace())
875        };
876
877        if matches!(kind, MemoryKind::Machine(kind) if kind.should_save_allocation_span()) {
878            ecx.machine
879                .allocation_spans
880                .borrow_mut()
881                .insert(id, (ecx.machine.current_span(), None));
882        }
883
884        interp_ok(AllocExtra { borrow_tracker, data_race, backtrace, sync: FxHashMap::default() })
885    }
886}
887
888impl VisitProvenance for MiriMachine<'_> {
889    fn visit_provenance(&self, visit: &mut VisitWith<'_>) {
890        #[rustfmt::skip]
891        let MiriMachine {
892            threads,
893            thread_cpu_affinity: _,
894            sync: _,
895            tls,
896            env_vars,
897            main_fn_ret_place,
898            argc,
899            argv,
900            cmd_line,
901            extern_statics,
902            dirs,
903            borrow_tracker,
904            data_race,
905            alloc_addresses,
906            fds,
907            epoll_interests:_,
908            tcx: _,
909            isolated_op: _,
910            validation: _,
911            monotonic_clock: _,
912            layouts: _,
913            static_roots: _,
914            profiler: _,
915            string_cache: _,
916            exported_symbols_cache: _,
917            backtrace_style: _,
918            local_crates: _,
919            rng: _,
920            tracked_alloc_ids: _,
921            track_alloc_accesses: _,
922            check_alignment: _,
923            cmpxchg_weak_failure_rate: _,
924            preemption_rate: _,
925            report_progress: _,
926            basic_block_count: _,
927            native_lib: _,
928            gc_interval: _,
929            since_gc: _,
930            num_cpus: _,
931            page_size: _,
932            stack_addr: _,
933            stack_size: _,
934            collect_leak_backtraces: _,
935            allocation_spans: _,
936            const_cache: _,
937            symbolic_alignment: _,
938            union_data_ranges: _,
939            pthread_mutex_sanity: _,
940            pthread_rwlock_sanity: _,
941            pthread_condvar_sanity: _,
942            sb_extern_type_warned: _,
943            #[cfg(unix)]
944            native_call_mem_warned: _,
945            reject_in_isolation_warned: _,
946            int2ptr_warned: _,
947            mangle_internal_symbol_cache: _,
948            force_intrinsic_fallback: _,
949        } = self;
950
951        threads.visit_provenance(visit);
952        tls.visit_provenance(visit);
953        env_vars.visit_provenance(visit);
954        dirs.visit_provenance(visit);
955        fds.visit_provenance(visit);
956        data_race.visit_provenance(visit);
957        borrow_tracker.visit_provenance(visit);
958        alloc_addresses.visit_provenance(visit);
959        main_fn_ret_place.visit_provenance(visit);
960        argc.visit_provenance(visit);
961        argv.visit_provenance(visit);
962        cmd_line.visit_provenance(visit);
963        for ptr in extern_statics.values() {
964            ptr.visit_provenance(visit);
965        }
966    }
967}
968
969/// A rustc InterpCx for Miri.
970pub type MiriInterpCx<'tcx> = InterpCx<'tcx, MiriMachine<'tcx>>;
971
972/// A little trait that's useful to be inherited by extension traits.
973pub trait MiriInterpCxExt<'tcx> {
974    fn eval_context_ref<'a>(&'a self) -> &'a MiriInterpCx<'tcx>;
975    fn eval_context_mut<'a>(&'a mut self) -> &'a mut MiriInterpCx<'tcx>;
976}
977impl<'tcx> MiriInterpCxExt<'tcx> for MiriInterpCx<'tcx> {
978    #[inline(always)]
979    fn eval_context_ref(&self) -> &MiriInterpCx<'tcx> {
980        self
981    }
982    #[inline(always)]
983    fn eval_context_mut(&mut self) -> &mut MiriInterpCx<'tcx> {
984        self
985    }
986}
987
988/// Machine hook implementations.
989impl<'tcx> Machine<'tcx> for MiriMachine<'tcx> {
990    type MemoryKind = MiriMemoryKind;
991    type ExtraFnVal = DynSym;
992
993    type FrameExtra = FrameExtra<'tcx>;
994    type AllocExtra = AllocExtra<'tcx>;
995
996    type Provenance = Provenance;
997    type ProvenanceExtra = ProvenanceExtra;
998    type Bytes = MiriAllocBytes;
999
1000    type MemoryMap =
1001        MonoHashMap<AllocId, (MemoryKind, Allocation<Provenance, Self::AllocExtra, Self::Bytes>)>;
1002
1003    const GLOBAL_KIND: Option<MiriMemoryKind> = Some(MiriMemoryKind::Global);
1004
1005    const PANIC_ON_ALLOC_FAIL: bool = false;
1006
1007    #[inline(always)]
1008    fn enforce_alignment(ecx: &MiriInterpCx<'tcx>) -> bool {
1009        ecx.machine.check_alignment != AlignmentCheck::None
1010    }
1011
1012    #[inline(always)]
1013    fn alignment_check(
1014        ecx: &MiriInterpCx<'tcx>,
1015        alloc_id: AllocId,
1016        alloc_align: Align,
1017        alloc_kind: AllocKind,
1018        offset: Size,
1019        align: Align,
1020    ) -> Option<Misalignment> {
1021        if ecx.machine.check_alignment != AlignmentCheck::Symbolic {
1022            // Just use the built-in check.
1023            return None;
1024        }
1025        if alloc_kind != AllocKind::LiveData {
1026            // Can't have any extra info here.
1027            return None;
1028        }
1029        // Let's see which alignment we have been promised for this allocation.
1030        let (promised_offset, promised_align) = ecx
1031            .machine
1032            .symbolic_alignment
1033            .borrow()
1034            .get(&alloc_id)
1035            .copied()
1036            .unwrap_or((Size::ZERO, alloc_align));
1037        if promised_align < align {
1038            // Definitely not enough.
1039            Some(Misalignment { has: promised_align, required: align })
1040        } else {
1041            // What's the offset between us and the promised alignment?
1042            let distance = offset.bytes().wrapping_sub(promised_offset.bytes());
1043            // That must also be aligned.
1044            if distance % align.bytes() == 0 {
1045                // All looking good!
1046                None
1047            } else {
1048                // The biggest power of two through which `distance` is divisible.
1049                let distance_pow2 = 1 << distance.trailing_zeros();
1050                Some(Misalignment {
1051                    has: Align::from_bytes(distance_pow2).unwrap(),
1052                    required: align,
1053                })
1054            }
1055        }
1056    }
1057
1058    #[inline(always)]
1059    fn enforce_validity(ecx: &MiriInterpCx<'tcx>, _layout: TyAndLayout<'tcx>) -> bool {
1060        ecx.machine.validation != ValidationMode::No
1061    }
1062    #[inline(always)]
1063    fn enforce_validity_recursively(
1064        ecx: &InterpCx<'tcx, Self>,
1065        _layout: TyAndLayout<'tcx>,
1066    ) -> bool {
1067        ecx.machine.validation == ValidationMode::Deep
1068    }
1069
1070    #[inline(always)]
1071    fn ignore_optional_overflow_checks(ecx: &MiriInterpCx<'tcx>) -> bool {
1072        !ecx.tcx.sess.overflow_checks()
1073    }
1074
1075    fn check_fn_target_features(
1076        ecx: &MiriInterpCx<'tcx>,
1077        instance: ty::Instance<'tcx>,
1078    ) -> InterpResult<'tcx> {
1079        let attrs = ecx.tcx.codegen_fn_attrs(instance.def_id());
1080        if attrs
1081            .target_features
1082            .iter()
1083            .any(|feature| !ecx.tcx.sess.target_features.contains(&feature.name))
1084        {
1085            let unavailable = attrs
1086                .target_features
1087                .iter()
1088                .filter(|&feature| {
1089                    !feature.implied && !ecx.tcx.sess.target_features.contains(&feature.name)
1090                })
1091                .fold(String::new(), |mut s, feature| {
1092                    if !s.is_empty() {
1093                        s.push_str(", ");
1094                    }
1095                    s.push_str(feature.name.as_str());
1096                    s
1097                });
1098            let msg = format!(
1099                "calling a function that requires unavailable target features: {unavailable}"
1100            );
1101            // On WASM, this is not UB, but instead gets rejected during validation of the module
1102            // (see #84988).
1103            if ecx.tcx.sess.target.is_like_wasm {
1104                throw_machine_stop!(TerminationInfo::Abort(msg));
1105            } else {
1106                throw_ub_format!("{msg}");
1107            }
1108        }
1109        interp_ok(())
1110    }
1111
1112    #[inline(always)]
1113    fn find_mir_or_eval_fn(
1114        ecx: &mut MiriInterpCx<'tcx>,
1115        instance: ty::Instance<'tcx>,
1116        abi: &FnAbi<'tcx, Ty<'tcx>>,
1117        args: &[FnArg<'tcx, Provenance>],
1118        dest: &MPlaceTy<'tcx>,
1119        ret: Option<mir::BasicBlock>,
1120        unwind: mir::UnwindAction,
1121    ) -> InterpResult<'tcx, Option<(&'tcx mir::Body<'tcx>, ty::Instance<'tcx>)>> {
1122        // For foreign items, try to see if we can emulate them.
1123        if ecx.tcx.is_foreign_item(instance.def_id()) {
1124            // An external function call that does not have a MIR body. We either find MIR elsewhere
1125            // or emulate its effect.
1126            // This will be Ok(None) if we're emulating the intrinsic entirely within Miri (no need
1127            // to run extra MIR), and Ok(Some(body)) if we found MIR to run for the
1128            // foreign function
1129            // Any needed call to `goto_block` will be performed by `emulate_foreign_item`.
1130            let args = ecx.copy_fn_args(args); // FIXME: Should `InPlace` arguments be reset to uninit?
1131            let link_name = Symbol::intern(ecx.tcx.symbol_name(instance).name);
1132            return ecx.emulate_foreign_item(link_name, abi, &args, dest, ret, unwind);
1133        }
1134
1135        // Otherwise, load the MIR.
1136        interp_ok(Some((ecx.load_mir(instance.def, None)?, instance)))
1137    }
1138
1139    #[inline(always)]
1140    fn call_extra_fn(
1141        ecx: &mut MiriInterpCx<'tcx>,
1142        fn_val: DynSym,
1143        abi: &FnAbi<'tcx, Ty<'tcx>>,
1144        args: &[FnArg<'tcx, Provenance>],
1145        dest: &MPlaceTy<'tcx>,
1146        ret: Option<mir::BasicBlock>,
1147        unwind: mir::UnwindAction,
1148    ) -> InterpResult<'tcx> {
1149        let args = ecx.copy_fn_args(args); // FIXME: Should `InPlace` arguments be reset to uninit?
1150        ecx.emulate_dyn_sym(fn_val, abi, &args, dest, ret, unwind)
1151    }
1152
1153    #[inline(always)]
1154    fn call_intrinsic(
1155        ecx: &mut MiriInterpCx<'tcx>,
1156        instance: ty::Instance<'tcx>,
1157        args: &[OpTy<'tcx>],
1158        dest: &MPlaceTy<'tcx>,
1159        ret: Option<mir::BasicBlock>,
1160        unwind: mir::UnwindAction,
1161    ) -> InterpResult<'tcx, Option<ty::Instance<'tcx>>> {
1162        ecx.call_intrinsic(instance, args, dest, ret, unwind)
1163    }
1164
1165    #[inline(always)]
1166    fn assert_panic(
1167        ecx: &mut MiriInterpCx<'tcx>,
1168        msg: &mir::AssertMessage<'tcx>,
1169        unwind: mir::UnwindAction,
1170    ) -> InterpResult<'tcx> {
1171        ecx.assert_panic(msg, unwind)
1172    }
1173
1174    fn panic_nounwind(ecx: &mut InterpCx<'tcx, Self>, msg: &str) -> InterpResult<'tcx> {
1175        ecx.start_panic_nounwind(msg)
1176    }
1177
1178    fn unwind_terminate(
1179        ecx: &mut InterpCx<'tcx, Self>,
1180        reason: mir::UnwindTerminateReason,
1181    ) -> InterpResult<'tcx> {
1182        // Call the lang item.
1183        let panic = ecx.tcx.lang_items().get(reason.lang_item()).unwrap();
1184        let panic = ty::Instance::mono(ecx.tcx.tcx, panic);
1185        ecx.call_function(
1186            panic,
1187            ExternAbi::Rust,
1188            &[],
1189            None,
1190            StackPopCleanup::Goto { ret: None, unwind: mir::UnwindAction::Unreachable },
1191        )?;
1192        interp_ok(())
1193    }
1194
1195    #[inline(always)]
1196    fn binary_ptr_op(
1197        ecx: &MiriInterpCx<'tcx>,
1198        bin_op: mir::BinOp,
1199        left: &ImmTy<'tcx>,
1200        right: &ImmTy<'tcx>,
1201    ) -> InterpResult<'tcx, ImmTy<'tcx>> {
1202        ecx.binary_ptr_op(bin_op, left, right)
1203    }
1204
1205    #[inline(always)]
1206    fn generate_nan<F1: Float + FloatConvert<F2>, F2: Float>(
1207        ecx: &InterpCx<'tcx, Self>,
1208        inputs: &[F1],
1209    ) -> F2 {
1210        ecx.generate_nan(inputs)
1211    }
1212
1213    #[inline(always)]
1214    fn apply_float_nondet(
1215        ecx: &mut InterpCx<'tcx, Self>,
1216        val: ImmTy<'tcx>,
1217    ) -> InterpResult<'tcx, ImmTy<'tcx>> {
1218        crate::math::apply_random_float_error_to_imm(ecx, val, 2 /* log2(4) */)
1219    }
1220
1221    #[inline(always)]
1222    fn equal_float_min_max<F: Float>(ecx: &MiriInterpCx<'tcx>, a: F, b: F) -> F {
1223        ecx.equal_float_min_max(a, b)
1224    }
1225
1226    #[inline(always)]
1227    fn ub_checks(ecx: &InterpCx<'tcx, Self>) -> InterpResult<'tcx, bool> {
1228        interp_ok(ecx.tcx.sess.ub_checks())
1229    }
1230
1231    #[inline(always)]
1232    fn contract_checks(ecx: &InterpCx<'tcx, Self>) -> InterpResult<'tcx, bool> {
1233        interp_ok(ecx.tcx.sess.contract_checks())
1234    }
1235
1236    #[inline(always)]
1237    fn thread_local_static_pointer(
1238        ecx: &mut MiriInterpCx<'tcx>,
1239        def_id: DefId,
1240    ) -> InterpResult<'tcx, StrictPointer> {
1241        ecx.get_or_create_thread_local_alloc(def_id)
1242    }
1243
1244    fn extern_static_pointer(
1245        ecx: &MiriInterpCx<'tcx>,
1246        def_id: DefId,
1247    ) -> InterpResult<'tcx, StrictPointer> {
1248        let link_name = Symbol::intern(ecx.tcx.symbol_name(Instance::mono(*ecx.tcx, def_id)).name);
1249        if let Some(&ptr) = ecx.machine.extern_statics.get(&link_name) {
1250            // Various parts of the engine rely on `get_alloc_info` for size and alignment
1251            // information. That uses the type information of this static.
1252            // Make sure it matches the Miri allocation for this.
1253            let Provenance::Concrete { alloc_id, .. } = ptr.provenance else {
1254                panic!("extern_statics cannot contain wildcards")
1255            };
1256            let info = ecx.get_alloc_info(alloc_id);
1257            let def_ty = ecx.tcx.type_of(def_id).instantiate_identity();
1258            let extern_decl_layout =
1259                ecx.tcx.layout_of(ecx.typing_env().as_query_input(def_ty)).unwrap();
1260            if extern_decl_layout.size != info.size || extern_decl_layout.align.abi != info.align {
1261                throw_unsup_format!(
1262                    "extern static `{link_name}` has been declared as `{krate}::{name}` \
1263                    with a size of {decl_size} bytes and alignment of {decl_align} bytes, \
1264                    but Miri emulates it via an extern static shim \
1265                    with a size of {shim_size} bytes and alignment of {shim_align} bytes",
1266                    name = ecx.tcx.def_path_str(def_id),
1267                    krate = ecx.tcx.crate_name(def_id.krate),
1268                    decl_size = extern_decl_layout.size.bytes(),
1269                    decl_align = extern_decl_layout.align.abi.bytes(),
1270                    shim_size = info.size.bytes(),
1271                    shim_align = info.align.bytes(),
1272                )
1273            }
1274            interp_ok(ptr)
1275        } else {
1276            throw_unsup_format!("extern static `{link_name}` is not supported by Miri",)
1277        }
1278    }
1279
1280    fn init_local_allocation(
1281        ecx: &MiriInterpCx<'tcx>,
1282        id: AllocId,
1283        kind: MemoryKind,
1284        size: Size,
1285        align: Align,
1286    ) -> InterpResult<'tcx, Self::AllocExtra> {
1287        assert!(kind != MiriMemoryKind::Global.into());
1288        MiriMachine::init_allocation(ecx, id, kind, size, align)
1289    }
1290
1291    fn adjust_alloc_root_pointer(
1292        ecx: &MiriInterpCx<'tcx>,
1293        ptr: interpret::Pointer<CtfeProvenance>,
1294        kind: Option<MemoryKind>,
1295    ) -> InterpResult<'tcx, interpret::Pointer<Provenance>> {
1296        let kind = kind.expect("we set our GLOBAL_KIND so this cannot be None");
1297        let alloc_id = ptr.provenance.alloc_id();
1298        if cfg!(debug_assertions) {
1299            // The machine promises to never call us on thread-local or extern statics.
1300            match ecx.tcx.try_get_global_alloc(alloc_id) {
1301                Some(GlobalAlloc::Static(def_id)) if ecx.tcx.is_thread_local_static(def_id) => {
1302                    panic!("adjust_alloc_root_pointer called on thread-local static")
1303                }
1304                Some(GlobalAlloc::Static(def_id)) if ecx.tcx.is_foreign_item(def_id) => {
1305                    panic!("adjust_alloc_root_pointer called on extern static")
1306                }
1307                _ => {}
1308            }
1309        }
1310        // FIXME: can we somehow preserve the immutability of `ptr`?
1311        let tag = if let Some(borrow_tracker) = &ecx.machine.borrow_tracker {
1312            borrow_tracker.borrow_mut().root_ptr_tag(alloc_id, &ecx.machine)
1313        } else {
1314            // Value does not matter, SB is disabled
1315            BorTag::default()
1316        };
1317        ecx.adjust_alloc_root_pointer(ptr, tag, kind)
1318    }
1319
1320    /// Called on `usize as ptr` casts.
1321    #[inline(always)]
1322    fn ptr_from_addr_cast(ecx: &MiriInterpCx<'tcx>, addr: u64) -> InterpResult<'tcx, Pointer> {
1323        ecx.ptr_from_addr_cast(addr)
1324    }
1325
1326    /// Called on `ptr as usize` casts.
1327    /// (Actually computing the resulting `usize` doesn't need machine help,
1328    /// that's just `Scalar::try_to_int`.)
1329    #[inline(always)]
1330    fn expose_provenance(
1331        ecx: &InterpCx<'tcx, Self>,
1332        provenance: Self::Provenance,
1333    ) -> InterpResult<'tcx> {
1334        ecx.expose_provenance(provenance)
1335    }
1336
1337    /// Convert a pointer with provenance into an allocation-offset pair and extra provenance info.
1338    /// `size` says how many bytes of memory are expected at that pointer. The *sign* of `size` can
1339    /// be used to disambiguate situations where a wildcard pointer sits right in between two
1340    /// allocations.
1341    ///
1342    /// If `ptr.provenance.get_alloc_id()` is `Some(p)`, the returned `AllocId` must be `p`.
1343    /// The resulting `AllocId` will just be used for that one step and the forgotten again
1344    /// (i.e., we'll never turn the data returned here back into a `Pointer` that might be
1345    /// stored in machine state).
1346    ///
1347    /// When this fails, that means the pointer does not point to a live allocation.
1348    fn ptr_get_alloc(
1349        ecx: &MiriInterpCx<'tcx>,
1350        ptr: StrictPointer,
1351        size: i64,
1352    ) -> Option<(AllocId, Size, Self::ProvenanceExtra)> {
1353        let rel = ecx.ptr_get_alloc(ptr, size);
1354
1355        rel.map(|(alloc_id, size)| {
1356            let tag = match ptr.provenance {
1357                Provenance::Concrete { tag, .. } => ProvenanceExtra::Concrete(tag),
1358                Provenance::Wildcard => ProvenanceExtra::Wildcard,
1359            };
1360            (alloc_id, size, tag)
1361        })
1362    }
1363
1364    /// Called to adjust global allocations to the Provenance and AllocExtra of this machine.
1365    ///
1366    /// If `alloc` contains pointers, then they are all pointing to globals.
1367    ///
1368    /// This should avoid copying if no work has to be done! If this returns an owned
1369    /// allocation (because a copy had to be done to adjust things), machine memory will
1370    /// cache the result. (This relies on `AllocMap::get_or` being able to add the
1371    /// owned allocation to the map even when the map is shared.)
1372    fn adjust_global_allocation<'b>(
1373        ecx: &InterpCx<'tcx, Self>,
1374        id: AllocId,
1375        alloc: &'b Allocation,
1376    ) -> InterpResult<'tcx, Cow<'b, Allocation<Self::Provenance, Self::AllocExtra, Self::Bytes>>>
1377    {
1378        let alloc = alloc.adjust_from_tcx(
1379            &ecx.tcx,
1380            |bytes, align| ecx.get_global_alloc_bytes(id, bytes, align),
1381            |ptr| ecx.global_root_pointer(ptr),
1382        )?;
1383        let kind = MiriMemoryKind::Global.into();
1384        let extra = MiriMachine::init_allocation(ecx, id, kind, alloc.size(), alloc.align)?;
1385        interp_ok(Cow::Owned(alloc.with_extra(extra)))
1386    }
1387
1388    #[inline(always)]
1389    fn before_memory_read(
1390        _tcx: TyCtxtAt<'tcx>,
1391        machine: &Self,
1392        alloc_extra: &AllocExtra<'tcx>,
1393        ptr: Pointer,
1394        (alloc_id, prov_extra): (AllocId, Self::ProvenanceExtra),
1395        range: AllocRange,
1396    ) -> InterpResult<'tcx> {
1397        if machine.track_alloc_accesses && machine.tracked_alloc_ids.contains(&alloc_id) {
1398            machine
1399                .emit_diagnostic(NonHaltingDiagnostic::AccessedAlloc(alloc_id, AccessKind::Read));
1400        }
1401        // The order of checks is deliberate, to prefer reporting a data race over a borrow tracker error.
1402        match &machine.data_race {
1403            GlobalDataRaceHandler::None => {}
1404            GlobalDataRaceHandler::Genmc(genmc_ctx) =>
1405                genmc_ctx.memory_load(machine, ptr.addr(), range.size)?,
1406            GlobalDataRaceHandler::Vclocks(_data_race) => {
1407                let AllocDataRaceHandler::Vclocks(data_race, weak_memory) = &alloc_extra.data_race
1408                else {
1409                    unreachable!();
1410                };
1411                data_race.read(alloc_id, range, NaReadType::Read, None, machine)?;
1412                if let Some(weak_memory) = weak_memory {
1413                    weak_memory.memory_accessed(range, machine.data_race.as_vclocks_ref().unwrap());
1414                }
1415            }
1416        }
1417        if let Some(borrow_tracker) = &alloc_extra.borrow_tracker {
1418            borrow_tracker.before_memory_read(alloc_id, prov_extra, range, machine)?;
1419        }
1420        interp_ok(())
1421    }
1422
1423    #[inline(always)]
1424    fn before_memory_write(
1425        _tcx: TyCtxtAt<'tcx>,
1426        machine: &mut Self,
1427        alloc_extra: &mut AllocExtra<'tcx>,
1428        ptr: Pointer,
1429        (alloc_id, prov_extra): (AllocId, Self::ProvenanceExtra),
1430        range: AllocRange,
1431    ) -> InterpResult<'tcx> {
1432        if machine.track_alloc_accesses && machine.tracked_alloc_ids.contains(&alloc_id) {
1433            machine
1434                .emit_diagnostic(NonHaltingDiagnostic::AccessedAlloc(alloc_id, AccessKind::Write));
1435        }
1436        match &machine.data_race {
1437            GlobalDataRaceHandler::None => {}
1438            GlobalDataRaceHandler::Genmc(genmc_ctx) => {
1439                genmc_ctx.memory_store(machine, ptr.addr(), range.size)?;
1440            }
1441            GlobalDataRaceHandler::Vclocks(_global_state) => {
1442                let AllocDataRaceHandler::Vclocks(data_race, weak_memory) =
1443                    &mut alloc_extra.data_race
1444                else {
1445                    unreachable!()
1446                };
1447                data_race.write(alloc_id, range, NaWriteType::Write, None, machine)?;
1448                if let Some(weak_memory) = weak_memory {
1449                    weak_memory.memory_accessed(range, machine.data_race.as_vclocks_ref().unwrap());
1450                }
1451            }
1452        }
1453        if let Some(borrow_tracker) = &mut alloc_extra.borrow_tracker {
1454            borrow_tracker.before_memory_write(alloc_id, prov_extra, range, machine)?;
1455        }
1456        interp_ok(())
1457    }
1458
1459    #[inline(always)]
1460    fn before_memory_deallocation(
1461        _tcx: TyCtxtAt<'tcx>,
1462        machine: &mut Self,
1463        alloc_extra: &mut AllocExtra<'tcx>,
1464        ptr: Pointer,
1465        (alloc_id, prove_extra): (AllocId, Self::ProvenanceExtra),
1466        size: Size,
1467        align: Align,
1468        kind: MemoryKind,
1469    ) -> InterpResult<'tcx> {
1470        if machine.tracked_alloc_ids.contains(&alloc_id) {
1471            machine.emit_diagnostic(NonHaltingDiagnostic::FreedAlloc(alloc_id));
1472        }
1473        match &machine.data_race {
1474            GlobalDataRaceHandler::None => {}
1475            GlobalDataRaceHandler::Genmc(genmc_ctx) =>
1476                genmc_ctx.handle_dealloc(machine, ptr.addr(), size, align, kind)?,
1477            GlobalDataRaceHandler::Vclocks(_global_state) => {
1478                let data_race = alloc_extra.data_race.as_vclocks_mut().unwrap();
1479                data_race.write(
1480                    alloc_id,
1481                    alloc_range(Size::ZERO, size),
1482                    NaWriteType::Deallocate,
1483                    None,
1484                    machine,
1485                )?;
1486            }
1487        }
1488        if let Some(borrow_tracker) = &mut alloc_extra.borrow_tracker {
1489            borrow_tracker.before_memory_deallocation(alloc_id, prove_extra, size, machine)?;
1490        }
1491        if let Some((_, deallocated_at)) = machine.allocation_spans.borrow_mut().get_mut(&alloc_id)
1492        {
1493            *deallocated_at = Some(machine.current_span());
1494        }
1495        machine.free_alloc_id(alloc_id, size, align, kind);
1496        interp_ok(())
1497    }
1498
1499    #[inline(always)]
1500    fn retag_ptr_value(
1501        ecx: &mut InterpCx<'tcx, Self>,
1502        kind: mir::RetagKind,
1503        val: &ImmTy<'tcx>,
1504    ) -> InterpResult<'tcx, ImmTy<'tcx>> {
1505        if ecx.machine.borrow_tracker.is_some() {
1506            ecx.retag_ptr_value(kind, val)
1507        } else {
1508            interp_ok(val.clone())
1509        }
1510    }
1511
1512    #[inline(always)]
1513    fn retag_place_contents(
1514        ecx: &mut InterpCx<'tcx, Self>,
1515        kind: mir::RetagKind,
1516        place: &PlaceTy<'tcx>,
1517    ) -> InterpResult<'tcx> {
1518        if ecx.machine.borrow_tracker.is_some() {
1519            ecx.retag_place_contents(kind, place)?;
1520        }
1521        interp_ok(())
1522    }
1523
1524    fn protect_in_place_function_argument(
1525        ecx: &mut InterpCx<'tcx, Self>,
1526        place: &MPlaceTy<'tcx>,
1527    ) -> InterpResult<'tcx> {
1528        // If we have a borrow tracker, we also have it set up protection so that all reads *and
1529        // writes* during this call are insta-UB.
1530        let protected_place = if ecx.machine.borrow_tracker.is_some() {
1531            ecx.protect_place(place)?
1532        } else {
1533            // No borrow tracker.
1534            place.clone()
1535        };
1536        // We do need to write `uninit` so that even after the call ends, the former contents of
1537        // this place cannot be observed any more. We do the write after retagging so that for
1538        // Tree Borrows, this is considered to activate the new tag.
1539        // Conveniently this also ensures that the place actually points to suitable memory.
1540        ecx.write_uninit(&protected_place)?;
1541        // Now we throw away the protected place, ensuring its tag is never used again.
1542        interp_ok(())
1543    }
1544
1545    #[inline(always)]
1546    fn init_frame(
1547        ecx: &mut InterpCx<'tcx, Self>,
1548        frame: Frame<'tcx, Provenance>,
1549    ) -> InterpResult<'tcx, Frame<'tcx, Provenance, FrameExtra<'tcx>>> {
1550        // Start recording our event before doing anything else
1551        let timing = if let Some(profiler) = ecx.machine.profiler.as_ref() {
1552            let fn_name = frame.instance().to_string();
1553            let entry = ecx.machine.string_cache.entry(fn_name.clone());
1554            let name = entry.or_insert_with(|| profiler.alloc_string(&*fn_name));
1555
1556            Some(profiler.start_recording_interval_event_detached(
1557                *name,
1558                measureme::EventId::from_label(*name),
1559                ecx.active_thread().to_u32(),
1560            ))
1561        } else {
1562            None
1563        };
1564
1565        let borrow_tracker = ecx.machine.borrow_tracker.as_ref();
1566
1567        let extra = FrameExtra {
1568            borrow_tracker: borrow_tracker.map(|bt| bt.borrow_mut().new_frame()),
1569            catch_unwind: None,
1570            timing,
1571            is_user_relevant: ecx.machine.is_user_relevant(&frame),
1572            salt: ecx.machine.rng.borrow_mut().random_range(0..ADDRS_PER_ANON_GLOBAL),
1573            data_race: ecx
1574                .machine
1575                .data_race
1576                .as_vclocks_ref()
1577                .map(|_| data_race::FrameState::default()),
1578        };
1579
1580        interp_ok(frame.with_extra(extra))
1581    }
1582
1583    fn stack<'a>(
1584        ecx: &'a InterpCx<'tcx, Self>,
1585    ) -> &'a [Frame<'tcx, Self::Provenance, Self::FrameExtra>] {
1586        ecx.active_thread_stack()
1587    }
1588
1589    fn stack_mut<'a>(
1590        ecx: &'a mut InterpCx<'tcx, Self>,
1591    ) -> &'a mut Vec<Frame<'tcx, Self::Provenance, Self::FrameExtra>> {
1592        ecx.active_thread_stack_mut()
1593    }
1594
1595    fn before_terminator(ecx: &mut InterpCx<'tcx, Self>) -> InterpResult<'tcx> {
1596        ecx.machine.basic_block_count += 1u64; // a u64 that is only incremented by 1 will "never" overflow
1597        ecx.machine.since_gc += 1;
1598        // Possibly report our progress. This will point at the terminator we are about to execute.
1599        if let Some(report_progress) = ecx.machine.report_progress {
1600            if ecx.machine.basic_block_count % u64::from(report_progress) == 0 {
1601                ecx.emit_diagnostic(NonHaltingDiagnostic::ProgressReport {
1602                    block_count: ecx.machine.basic_block_count,
1603                });
1604            }
1605        }
1606
1607        // Search for BorTags to find all live pointers, then remove all other tags from borrow
1608        // stacks.
1609        // When debug assertions are enabled, run the GC as often as possible so that any cases
1610        // where it mistakenly removes an important tag become visible.
1611        if ecx.machine.gc_interval > 0 && ecx.machine.since_gc >= ecx.machine.gc_interval {
1612            ecx.machine.since_gc = 0;
1613            ecx.run_provenance_gc();
1614        }
1615
1616        // These are our preemption points.
1617        // (This will only take effect after the terminator has been executed.)
1618        ecx.maybe_preempt_active_thread();
1619
1620        // Make sure some time passes.
1621        ecx.machine.monotonic_clock.tick();
1622
1623        interp_ok(())
1624    }
1625
1626    #[inline(always)]
1627    fn after_stack_push(ecx: &mut InterpCx<'tcx, Self>) -> InterpResult<'tcx> {
1628        if ecx.frame().extra.is_user_relevant {
1629            // We just pushed a local frame, so we know that the topmost local frame is the topmost
1630            // frame. If we push a non-local frame, there's no need to do anything.
1631            let stack_len = ecx.active_thread_stack().len();
1632            ecx.active_thread_mut().set_top_user_relevant_frame(stack_len - 1);
1633        }
1634        interp_ok(())
1635    }
1636
1637    fn before_stack_pop(
1638        ecx: &InterpCx<'tcx, Self>,
1639        frame: &Frame<'tcx, Self::Provenance, Self::FrameExtra>,
1640    ) -> InterpResult<'tcx> {
1641        // We want this *before* the return value copy, because the return place itself is protected
1642        // until we do `end_call` here.
1643        if ecx.machine.borrow_tracker.is_some() {
1644            ecx.on_stack_pop(frame)?;
1645        }
1646        // tracing-tree can autoamtically annotate scope changes, but it gets very confused by our
1647        // concurrency and what it prints is just plain wrong. So we print our own information
1648        // instead. (Cc https://github.com/rust-lang/miri/issues/2266)
1649        info!("Leaving {}", ecx.frame().instance());
1650        interp_ok(())
1651    }
1652
1653    #[inline(always)]
1654    fn after_stack_pop(
1655        ecx: &mut InterpCx<'tcx, Self>,
1656        frame: Frame<'tcx, Provenance, FrameExtra<'tcx>>,
1657        unwinding: bool,
1658    ) -> InterpResult<'tcx, ReturnAction> {
1659        if frame.extra.is_user_relevant {
1660            // All that we store is whether or not the frame we just removed is local, so now we
1661            // have no idea where the next topmost local frame is. So we recompute it.
1662            // (If this ever becomes a bottleneck, we could have `push` store the previous
1663            // user-relevant frame and restore that here.)
1664            ecx.active_thread_mut().recompute_top_user_relevant_frame();
1665        }
1666        let res = {
1667            // Move `frame`` into a sub-scope so we control when it will be dropped.
1668            let mut frame = frame;
1669            let timing = frame.extra.timing.take();
1670            let res = ecx.handle_stack_pop_unwind(frame.extra, unwinding);
1671            if let Some(profiler) = ecx.machine.profiler.as_ref() {
1672                profiler.finish_recording_interval_event(timing.unwrap());
1673            }
1674            res
1675        };
1676        // Needs to be done after dropping frame to show up on the right nesting level.
1677        // (Cc https://github.com/rust-lang/miri/issues/2266)
1678        if !ecx.active_thread_stack().is_empty() {
1679            info!("Continuing in {}", ecx.frame().instance());
1680        }
1681        res
1682    }
1683
1684    fn after_local_read(
1685        ecx: &InterpCx<'tcx, Self>,
1686        frame: &Frame<'tcx, Provenance, FrameExtra<'tcx>>,
1687        local: mir::Local,
1688    ) -> InterpResult<'tcx> {
1689        if let Some(data_race) = &frame.extra.data_race {
1690            data_race.local_read(local, &ecx.machine);
1691        }
1692        interp_ok(())
1693    }
1694
1695    fn after_local_write(
1696        ecx: &mut InterpCx<'tcx, Self>,
1697        local: mir::Local,
1698        storage_live: bool,
1699    ) -> InterpResult<'tcx> {
1700        if let Some(data_race) = &ecx.frame().extra.data_race {
1701            data_race.local_write(local, storage_live, &ecx.machine);
1702        }
1703        interp_ok(())
1704    }
1705
1706    fn after_local_moved_to_memory(
1707        ecx: &mut InterpCx<'tcx, Self>,
1708        local: mir::Local,
1709        mplace: &MPlaceTy<'tcx>,
1710    ) -> InterpResult<'tcx> {
1711        let Some(Provenance::Concrete { alloc_id, .. }) = mplace.ptr().provenance else {
1712            panic!("after_local_allocated should only be called on fresh allocations");
1713        };
1714        // Record the span where this was allocated: the declaration of the local.
1715        let local_decl = &ecx.frame().body().local_decls[local];
1716        let span = local_decl.source_info.span;
1717        ecx.machine.allocation_spans.borrow_mut().insert(alloc_id, (span, None));
1718        // The data race system has to fix the clocks used for this write.
1719        let (alloc_info, machine) = ecx.get_alloc_extra_mut(alloc_id)?;
1720        if let Some(data_race) =
1721            &machine.threads.active_thread_stack().last().unwrap().extra.data_race
1722        {
1723            data_race.local_moved_to_memory(
1724                local,
1725                alloc_info.data_race.as_vclocks_mut().unwrap(),
1726                machine,
1727            );
1728        }
1729        interp_ok(())
1730    }
1731
1732    fn eval_mir_constant<F>(
1733        ecx: &InterpCx<'tcx, Self>,
1734        val: mir::Const<'tcx>,
1735        span: Span,
1736        layout: Option<TyAndLayout<'tcx>>,
1737        eval: F,
1738    ) -> InterpResult<'tcx, OpTy<'tcx>>
1739    where
1740        F: Fn(
1741            &InterpCx<'tcx, Self>,
1742            mir::Const<'tcx>,
1743            Span,
1744            Option<TyAndLayout<'tcx>>,
1745        ) -> InterpResult<'tcx, OpTy<'tcx>>,
1746    {
1747        let frame = ecx.active_thread_stack().last().unwrap();
1748        let mut cache = ecx.machine.const_cache.borrow_mut();
1749        match cache.entry((val, frame.extra.salt)) {
1750            Entry::Vacant(ve) => {
1751                let op = eval(ecx, val, span, layout)?;
1752                ve.insert(op.clone());
1753                interp_ok(op)
1754            }
1755            Entry::Occupied(oe) => interp_ok(oe.get().clone()),
1756        }
1757    }
1758
1759    fn get_global_alloc_salt(
1760        ecx: &InterpCx<'tcx, Self>,
1761        instance: Option<ty::Instance<'tcx>>,
1762    ) -> usize {
1763        let unique = if let Some(instance) = instance {
1764            // Functions cannot be identified by pointers, as asm-equal functions can get
1765            // deduplicated by the linker (we set the "unnamed_addr" attribute for LLVM) and
1766            // functions can be duplicated across crates. We thus generate a new `AllocId` for every
1767            // mention of a function. This means that `main as fn() == main as fn()` is false, while
1768            // `let x = main as fn(); x == x` is true. However, as a quality-of-life feature it can
1769            // be useful to identify certain functions uniquely, e.g. for backtraces. So we identify
1770            // whether codegen will actually emit duplicate functions. It does that when they have
1771            // non-lifetime generics, or when they can be inlined. All other functions are given a
1772            // unique address. This is not a stable guarantee! The `inline` attribute is a hint and
1773            // cannot be relied upon for anything. But if we don't do this, the
1774            // `__rust_begin_short_backtrace`/`__rust_end_short_backtrace` logic breaks and panic
1775            // backtraces look terrible.
1776            let is_generic = instance
1777                .args
1778                .into_iter()
1779                .any(|kind| !matches!(kind.unpack(), ty::GenericArgKind::Lifetime(_)));
1780            let can_be_inlined = matches!(
1781                ecx.tcx.sess.opts.unstable_opts.cross_crate_inline_threshold,
1782                InliningThreshold::Always
1783            ) || !matches!(
1784                ecx.tcx.codegen_fn_attrs(instance.def_id()).inline,
1785                InlineAttr::Never
1786            );
1787            !is_generic && !can_be_inlined
1788        } else {
1789            // Non-functions are never unique.
1790            false
1791        };
1792        // Always use the same salt if the allocation is unique.
1793        if unique {
1794            CTFE_ALLOC_SALT
1795        } else {
1796            ecx.machine.rng.borrow_mut().random_range(0..ADDRS_PER_ANON_GLOBAL)
1797        }
1798    }
1799
1800    fn cached_union_data_range<'e>(
1801        ecx: &'e mut InterpCx<'tcx, Self>,
1802        ty: Ty<'tcx>,
1803        compute_range: impl FnOnce() -> RangeSet,
1804    ) -> Cow<'e, RangeSet> {
1805        Cow::Borrowed(ecx.machine.union_data_ranges.entry(ty).or_insert_with(compute_range))
1806    }
1807}
1808
1809/// Trait for callbacks handling asynchronous machine operations.
1810pub trait MachineCallback<'tcx, T>: VisitProvenance {
1811    /// The function to be invoked when the callback is fired.
1812    fn call(
1813        self: Box<Self>,
1814        ecx: &mut InterpCx<'tcx, MiriMachine<'tcx>>,
1815        arg: T,
1816    ) -> InterpResult<'tcx>;
1817}
1818
1819/// Type alias for boxed machine callbacks with generic argument type.
1820pub type DynMachineCallback<'tcx, T> = Box<dyn MachineCallback<'tcx, T> + 'tcx>;
1821
1822/// Creates a `DynMachineCallback`:
1823///
1824/// ```rust
1825/// callback!(
1826///     @capture<'tcx> {
1827///         var1: Ty1,
1828///         var2: Ty2<'tcx>,
1829///     }
1830///     |this, arg: ArgTy| {
1831///         // Implement the callback here.
1832///         todo!()
1833///     }
1834/// )
1835/// ```
1836///
1837/// All the argument types must implement `VisitProvenance`.
1838#[macro_export]
1839macro_rules! callback {
1840    (@capture<$tcx:lifetime $(,)? $($lft:lifetime),*>
1841        { $($name:ident: $type:ty),* $(,)? }
1842     |$this:ident, $arg:ident: $arg_ty:ty| $body:expr $(,)?) => {{
1843        struct Callback<$tcx, $($lft),*> {
1844            $($name: $type,)*
1845            _phantom: std::marker::PhantomData<&$tcx ()>,
1846        }
1847
1848        impl<$tcx, $($lft),*> VisitProvenance for Callback<$tcx, $($lft),*> {
1849            fn visit_provenance(&self, _visit: &mut VisitWith<'_>) {
1850                $(
1851                    self.$name.visit_provenance(_visit);
1852                )*
1853            }
1854        }
1855
1856        impl<$tcx, $($lft),*> MachineCallback<$tcx, $arg_ty> for Callback<$tcx, $($lft),*> {
1857            fn call(
1858                self: Box<Self>,
1859                $this: &mut MiriInterpCx<$tcx>,
1860                $arg: $arg_ty
1861            ) -> InterpResult<$tcx> {
1862                #[allow(unused_variables)]
1863                let Callback { $($name,)* _phantom } = *self;
1864                $body
1865            }
1866        }
1867
1868        Box::new(Callback {
1869            $($name,)*
1870            _phantom: std::marker::PhantomData
1871        })
1872    }};
1873}