+++ /dev/null
-//! This module contains everything needed to instantiate an interpreter.
-//! This separation exists to ensure that no fancy miri features like
-//! interpreting common C functions leak into CTFE.
-
-use std::borrow::{Borrow, Cow};
-use std::fmt::Debug;
-use std::hash::Hash;
-
-use rustc_middle::mir;
-use rustc_middle::ty::{self, Ty};
-use rustc_span::def_id::DefId;
-use rustc_target::abi::Size;
-use rustc_target::spec::abi::Abi;
-
-use super::{
- AllocId, AllocRange, Allocation, Frame, ImmTy, InterpCx, InterpResult, LocalValue, MemPlace,
- Memory, MemoryKind, OpTy, Operand, PlaceTy, Pointer, Provenance, Scalar, StackPopUnwind,
-};
-
-/// Data returned by Machine::stack_pop,
-/// to provide further control over the popping of the stack frame
-#[derive(Eq, PartialEq, Debug, Copy, Clone)]
-pub enum StackPopJump {
- /// Indicates that no special handling should be
- /// done - we'll either return normally or unwind
- /// based on the terminator for the function
- /// we're leaving.
- Normal,
-
- /// Indicates that we should *not* jump to the return/unwind address, as the callback already
- /// took care of everything.
- NoJump,
-}
-
-/// Whether this kind of memory is allowed to leak
-pub trait MayLeak: Copy {
- fn may_leak(self) -> bool;
-}
-
-/// The functionality needed by memory to manage its allocations
-pub trait AllocMap<K: Hash + Eq, V> {
- /// Tests if the map contains the given key.
- /// Deliberately takes `&mut` because that is sufficient, and some implementations
- /// can be more efficient then (using `RefCell::get_mut`).
- fn contains_key<Q: ?Sized + Hash + Eq>(&mut self, k: &Q) -> bool
- where
- K: Borrow<Q>;
-
- /// Inserts a new entry into the map.
- fn insert(&mut self, k: K, v: V) -> Option<V>;
-
- /// Removes an entry from the map.
- fn remove<Q: ?Sized + Hash + Eq>(&mut self, k: &Q) -> Option<V>
- where
- K: Borrow<Q>;
-
- /// Returns data based on the keys and values in the map.
- fn filter_map_collect<T>(&self, f: impl FnMut(&K, &V) -> Option<T>) -> Vec<T>;
-
- /// Returns a reference to entry `k`. If no such entry exists, call
- /// `vacant` and either forward its error, or add its result to the map
- /// and return a reference to *that*.
- fn get_or<E>(&self, k: K, vacant: impl FnOnce() -> Result<V, E>) -> Result<&V, E>;
-
- /// Returns a mutable reference to entry `k`. If no such entry exists, call
- /// `vacant` and either forward its error, or add its result to the map
- /// and return a reference to *that*.
- fn get_mut_or<E>(&mut self, k: K, vacant: impl FnOnce() -> Result<V, E>) -> Result<&mut V, E>;
-
- /// Read-only lookup.
- fn get(&self, k: K) -> Option<&V> {
- self.get_or(k, || Err(())).ok()
- }
-
- /// Mutable lookup.
- fn get_mut(&mut self, k: K) -> Option<&mut V> {
- self.get_mut_or(k, || Err(())).ok()
- }
-}
-
-/// Methods of this trait signifies a point where CTFE evaluation would fail
-/// and some use case dependent behaviour can instead be applied.
-pub trait Machine<'mir, 'tcx>: Sized {
- /// Additional memory kinds a machine wishes to distinguish from the builtin ones
- type MemoryKind: Debug + std::fmt::Display + MayLeak + Eq + 'static;
-
- /// Pointers are "tagged" with provenance information; typically the `AllocId` they belong to.
- type PointerTag: Provenance + Eq + Hash + 'static;
-
- /// Machines can define extra (non-instance) things that represent values of function pointers.
- /// For example, Miri uses this to return a function pointer from `dlsym`
- /// that can later be called to execute the right thing.
- type ExtraFnVal: Debug + Copy;
-
- /// Extra data stored in every call frame.
- type FrameExtra;
-
- /// Extra data stored in memory. A reference to this is available when `AllocExtra`
- /// gets initialized, so you can e.g., have an `Rc` here if there is global state you
- /// need access to in the `AllocExtra` hooks.
- type MemoryExtra;
-
- /// Extra data stored in every allocation.
- type AllocExtra: Debug + Clone + 'static;
-
- /// Memory's allocation map
- type MemoryMap: AllocMap<
- AllocId,
- (MemoryKind<Self::MemoryKind>, Allocation<Self::PointerTag, Self::AllocExtra>),
- > + Default
- + Clone;
-
- /// The memory kind to use for copied global memory (held in `tcx`) --
- /// or None if such memory should not be mutated and thus any such attempt will cause
- /// a `ModifiedStatic` error to be raised.
- /// Statics are copied under two circumstances: When they are mutated, and when
- /// `tag_allocation` (see below) returns an owned allocation
- /// that is added to the memory so that the work is not done twice.
- const GLOBAL_KIND: Option<Self::MemoryKind>;
-
- /// Should the machine panic on allocation failures?
- const PANIC_ON_ALLOC_FAIL: bool;
-
- /// Whether memory accesses should be alignment-checked.
- fn enforce_alignment(memory_extra: &Self::MemoryExtra) -> bool;
-
- /// Whether, when checking alignment, we should `force_int` and thus support
- /// custom alignment logic based on whatever the integer address happens to be.
- fn force_int_for_alignment_check(memory_extra: &Self::MemoryExtra) -> bool;
-
- /// Whether to enforce the validity invariant
- fn enforce_validity(ecx: &InterpCx<'mir, 'tcx, Self>) -> bool;
-
- /// Whether function calls should be [ABI](Abi)-checked.
- fn enforce_abi(_ecx: &InterpCx<'mir, 'tcx, Self>) -> bool {
- true
- }
-
- /// Entry point for obtaining the MIR of anything that should get evaluated.
- /// So not just functions and shims, but also const/static initializers, anonymous
- /// constants, ...
- fn load_mir(
- ecx: &InterpCx<'mir, 'tcx, Self>,
- instance: ty::InstanceDef<'tcx>,
- ) -> InterpResult<'tcx, &'tcx mir::Body<'tcx>> {
- Ok(ecx.tcx.instance_mir(instance))
- }
-
- /// Entry point to all function calls.
- ///
- /// Returns either the mir to use for the call, or `None` if execution should
- /// just proceed (which usually means this hook did all the work that the
- /// called function should usually have done). In the latter case, it is
- /// this hook's responsibility to advance the instruction pointer!
- /// (This is to support functions like `__rust_maybe_catch_panic` that neither find a MIR
- /// nor just jump to `ret`, but instead push their own stack frame.)
- /// Passing `dest`and `ret` in the same `Option` proved very annoying when only one of them
- /// was used.
- fn find_mir_or_eval_fn(
- ecx: &mut InterpCx<'mir, 'tcx, Self>,
- instance: ty::Instance<'tcx>,
- abi: Abi,
- args: &[OpTy<'tcx, Self::PointerTag>],
- ret: Option<(&PlaceTy<'tcx, Self::PointerTag>, mir::BasicBlock)>,
- unwind: StackPopUnwind,
- ) -> InterpResult<'tcx, Option<&'mir mir::Body<'tcx>>>;
-
- /// Execute `fn_val`. It is the hook's responsibility to advance the instruction
- /// pointer as appropriate.
- fn call_extra_fn(
- ecx: &mut InterpCx<'mir, 'tcx, Self>,
- fn_val: Self::ExtraFnVal,
- abi: Abi,
- args: &[OpTy<'tcx, Self::PointerTag>],
- ret: Option<(&PlaceTy<'tcx, Self::PointerTag>, mir::BasicBlock)>,
- unwind: StackPopUnwind,
- ) -> InterpResult<'tcx>;
-
- /// Directly process an intrinsic without pushing a stack frame. It is the hook's
- /// responsibility to advance the instruction pointer as appropriate.
- fn call_intrinsic(
- ecx: &mut InterpCx<'mir, 'tcx, Self>,
- instance: ty::Instance<'tcx>,
- args: &[OpTy<'tcx, Self::PointerTag>],
- ret: Option<(&PlaceTy<'tcx, Self::PointerTag>, mir::BasicBlock)>,
- unwind: StackPopUnwind,
- ) -> InterpResult<'tcx>;
-
- /// Called to evaluate `Assert` MIR terminators that trigger a panic.
- fn assert_panic(
- ecx: &mut InterpCx<'mir, 'tcx, Self>,
- msg: &mir::AssertMessage<'tcx>,
- unwind: Option<mir::BasicBlock>,
- ) -> InterpResult<'tcx>;
-
- /// Called to evaluate `Abort` MIR terminator.
- fn abort(_ecx: &mut InterpCx<'mir, 'tcx, Self>, _msg: String) -> InterpResult<'tcx, !> {
- throw_unsup_format!("aborting execution is not supported")
- }
-
- /// Called for all binary operations where the LHS has pointer type.
- ///
- /// Returns a (value, overflowed) pair if the operation succeeded
- fn binary_ptr_op(
- ecx: &InterpCx<'mir, 'tcx, Self>,
- bin_op: mir::BinOp,
- left: &ImmTy<'tcx, Self::PointerTag>,
- right: &ImmTy<'tcx, Self::PointerTag>,
- ) -> InterpResult<'tcx, (Scalar<Self::PointerTag>, bool, Ty<'tcx>)>;
-
- /// Heap allocations via the `box` keyword.
- fn box_alloc(
- ecx: &mut InterpCx<'mir, 'tcx, Self>,
- dest: &PlaceTy<'tcx, Self::PointerTag>,
- ) -> InterpResult<'tcx>;
-
- /// Called to read the specified `local` from the `frame`.
- /// Since reading a ZST is not actually accessing memory or locals, this is never invoked
- /// for ZST reads.
- #[inline]
- fn access_local(
- _ecx: &InterpCx<'mir, 'tcx, Self>,
- frame: &Frame<'mir, 'tcx, Self::PointerTag, Self::FrameExtra>,
- local: mir::Local,
- ) -> InterpResult<'tcx, Operand<Self::PointerTag>> {
- frame.locals[local].access()
- }
-
- /// Called to write the specified `local` from the `frame`.
- /// Since writing a ZST is not actually accessing memory or locals, this is never invoked
- /// for ZST reads.
- #[inline]
- fn access_local_mut<'a>(
- ecx: &'a mut InterpCx<'mir, 'tcx, Self>,
- frame: usize,
- local: mir::Local,
- ) -> InterpResult<'tcx, Result<&'a mut LocalValue<Self::PointerTag>, MemPlace<Self::PointerTag>>>
- where
- 'tcx: 'mir,
- {
- ecx.stack_mut()[frame].locals[local].access_mut()
- }
-
- /// Called before a basic block terminator is executed.
- /// You can use this to detect endlessly running programs.
- #[inline]
- fn before_terminator(_ecx: &mut InterpCx<'mir, 'tcx, Self>) -> InterpResult<'tcx> {
- Ok(())
- }
-
- /// Called before a global allocation is accessed.
- /// `def_id` is `Some` if this is the "lazy" allocation of a static.
- #[inline]
- fn before_access_global(
- _memory_extra: &Self::MemoryExtra,
- _alloc_id: AllocId,
- _allocation: &Allocation,
- _static_def_id: Option<DefId>,
- _is_write: bool,
- ) -> InterpResult<'tcx> {
- Ok(())
- }
-
- /// Return the `AllocId` for the given thread-local static in the current thread.
- fn thread_local_static_base_pointer(
- _ecx: &mut InterpCx<'mir, 'tcx, Self>,
- def_id: DefId,
- ) -> InterpResult<'tcx, Pointer<Self::PointerTag>> {
- throw_unsup!(ThreadLocalStatic(def_id))
- }
-
- /// Return the root pointer for the given `extern static`.
- fn extern_static_base_pointer(
- mem: &Memory<'mir, 'tcx, Self>,
- def_id: DefId,
- ) -> InterpResult<'tcx, Pointer<Self::PointerTag>>;
-
- /// Return a "base" pointer for the given allocation: the one that is used for direct
- /// accesses to this static/const/fn allocation, or the one returned from the heap allocator.
- ///
- /// Not called on `extern` or thread-local statics (those use the methods above).
- fn tag_alloc_base_pointer(
- mem: &Memory<'mir, 'tcx, Self>,
- ptr: Pointer,
- ) -> Pointer<Self::PointerTag>;
-
- /// "Int-to-pointer cast"
- fn ptr_from_addr(
- mem: &Memory<'mir, 'tcx, Self>,
- addr: u64,
- ) -> Pointer<Option<Self::PointerTag>>;
-
- /// Convert a pointer with provenance into an allocation-offset pair.
- fn ptr_get_alloc(
- mem: &Memory<'mir, 'tcx, Self>,
- ptr: Pointer<Self::PointerTag>,
- ) -> (AllocId, Size);
-
- /// Called to initialize the "extra" state of an allocation and make the pointers
- /// it contains (in relocations) tagged. The way we construct allocations is
- /// to always first construct it without extra and then add the extra.
- /// This keeps uniform code paths for handling both allocations created by CTFE
- /// for globals, and allocations created by Miri during evaluation.
- ///
- /// `kind` is the kind of the allocation being tagged; it can be `None` when
- /// it's a global and `GLOBAL_KIND` is `None`.
- ///
- /// This should avoid copying if no work has to be done! If this returns an owned
- /// allocation (because a copy had to be done to add tags or metadata), machine memory will
- /// cache the result. (This relies on `AllocMap::get_or` being able to add the
- /// owned allocation to the map even when the map is shared.)
- fn init_allocation_extra<'b>(
- mem: &Memory<'mir, 'tcx, Self>,
- id: AllocId,
- alloc: Cow<'b, Allocation>,
- kind: Option<MemoryKind<Self::MemoryKind>>,
- ) -> Cow<'b, Allocation<Self::PointerTag, Self::AllocExtra>>;
-
- /// Hook for performing extra checks on a memory read access.
- ///
- /// Takes read-only access to the allocation so we can keep all the memory read
- /// operations take `&self`. Use a `RefCell` in `AllocExtra` if you
- /// need to mutate.
- #[inline(always)]
- fn memory_read(
- _memory_extra: &Self::MemoryExtra,
- _alloc_extra: &Self::AllocExtra,
- _tag: Self::PointerTag,
- _range: AllocRange,
- ) -> InterpResult<'tcx> {
- Ok(())
- }
-
- /// Hook for performing extra checks on a memory write access.
- #[inline(always)]
- fn memory_written(
- _memory_extra: &mut Self::MemoryExtra,
- _alloc_extra: &mut Self::AllocExtra,
- _tag: Self::PointerTag,
- _range: AllocRange,
- ) -> InterpResult<'tcx> {
- Ok(())
- }
-
- /// Hook for performing extra operations on a memory deallocation.
- #[inline(always)]
- fn memory_deallocated(
- _memory_extra: &mut Self::MemoryExtra,
- _alloc_extra: &mut Self::AllocExtra,
- _tag: Self::PointerTag,
- _range: AllocRange,
- ) -> InterpResult<'tcx> {
- Ok(())
- }
-
- /// Executes a retagging operation.
- #[inline]
- fn retag(
- _ecx: &mut InterpCx<'mir, 'tcx, Self>,
- _kind: mir::RetagKind,
- _place: &PlaceTy<'tcx, Self::PointerTag>,
- ) -> InterpResult<'tcx> {
- Ok(())
- }
-
- /// Called immediately before a new stack frame gets pushed.
- fn init_frame_extra(
- ecx: &mut InterpCx<'mir, 'tcx, Self>,
- frame: Frame<'mir, 'tcx, Self::PointerTag>,
- ) -> InterpResult<'tcx, Frame<'mir, 'tcx, Self::PointerTag, Self::FrameExtra>>;
-
- /// Borrow the current thread's stack.
- fn stack(
- ecx: &'a InterpCx<'mir, 'tcx, Self>,
- ) -> &'a [Frame<'mir, 'tcx, Self::PointerTag, Self::FrameExtra>];
-
- /// Mutably borrow the current thread's stack.
- fn stack_mut(
- ecx: &'a mut InterpCx<'mir, 'tcx, Self>,
- ) -> &'a mut Vec<Frame<'mir, 'tcx, Self::PointerTag, Self::FrameExtra>>;
-
- /// Called immediately after a stack frame got pushed and its locals got initialized.
- fn after_stack_push(_ecx: &mut InterpCx<'mir, 'tcx, Self>) -> InterpResult<'tcx> {
- Ok(())
- }
-
- /// Called immediately after a stack frame got popped, but before jumping back to the caller.
- fn after_stack_pop(
- _ecx: &mut InterpCx<'mir, 'tcx, Self>,
- _frame: Frame<'mir, 'tcx, Self::PointerTag, Self::FrameExtra>,
- _unwinding: bool,
- ) -> InterpResult<'tcx, StackPopJump> {
- // By default, we do not support unwinding from panics
- Ok(StackPopJump::Normal)
- }
-}
-
-// A lot of the flexibility above is just needed for `Miri`, but all "compile-time" machines
-// (CTFE and ConstProp) use the same instance. Here, we share that code.
-pub macro compile_time_machine(<$mir: lifetime, $tcx: lifetime>) {
- type PointerTag = AllocId;
- type ExtraFnVal = !;
-
- type MemoryMap =
- rustc_data_structures::fx::FxHashMap<AllocId, (MemoryKind<Self::MemoryKind>, Allocation)>;
- const GLOBAL_KIND: Option<Self::MemoryKind> = None; // no copying of globals from `tcx` to machine memory
-
- type AllocExtra = ();
- type FrameExtra = ();
-
- #[inline(always)]
- fn enforce_alignment(_memory_extra: &Self::MemoryExtra) -> bool {
- // We do not check for alignment to avoid having to carry an `Align`
- // in `ConstValue::ByRef`.
- false
- }
-
- #[inline(always)]
- fn force_int_for_alignment_check(_memory_extra: &Self::MemoryExtra) -> bool {
- // We do not support `force_int`.
- false
- }
-
- #[inline(always)]
- fn enforce_validity(_ecx: &InterpCx<$mir, $tcx, Self>) -> bool {
- false // for now, we don't enforce validity
- }
-
- #[inline(always)]
- fn call_extra_fn(
- _ecx: &mut InterpCx<$mir, $tcx, Self>,
- fn_val: !,
- _abi: Abi,
- _args: &[OpTy<$tcx>],
- _ret: Option<(&PlaceTy<$tcx>, mir::BasicBlock)>,
- _unwind: StackPopUnwind,
- ) -> InterpResult<$tcx> {
- match fn_val {}
- }
-
- #[inline(always)]
- fn init_allocation_extra<'b>(
- _mem: &Memory<$mir, $tcx, Self>,
- _id: AllocId,
- alloc: Cow<'b, Allocation>,
- _kind: Option<MemoryKind<Self::MemoryKind>>,
- ) -> Cow<'b, Allocation<Self::PointerTag>> {
- // We do not use a tag so we can just cheaply forward the allocation
- alloc
- }
-
- fn extern_static_base_pointer(
- mem: &Memory<$mir, $tcx, Self>,
- def_id: DefId,
- ) -> InterpResult<$tcx, Pointer> {
- // Use the `AllocId` associated with the `DefId`. Any actual *access* will fail.
- Ok(Pointer::new(mem.tcx.create_static_alloc(def_id), Size::ZERO))
- }
-
- #[inline(always)]
- fn tag_alloc_base_pointer(
- _mem: &Memory<$mir, $tcx, Self>,
- ptr: Pointer<AllocId>,
- ) -> Pointer<AllocId> {
- ptr
- }
-
- #[inline(always)]
- fn ptr_from_addr(_mem: &Memory<$mir, $tcx, Self>, addr: u64) -> Pointer<Option<AllocId>> {
- Pointer::new(None, Size::from_bytes(addr))
- }
-
- #[inline(always)]
- fn ptr_get_alloc(_mem: &Memory<$mir, $tcx, Self>, ptr: Pointer<AllocId>) -> (AllocId, Size) {
- // We know `offset` is relative to the allocation, so we can use `into_parts`.
- let (alloc_id, offset) = ptr.into_parts();
- (alloc_id, offset)
- }
-}
projects / rustc.git / blobdiff