Struct rustc_const_eval::const_eval::CompileTimeInterpreter

pub struct CompileTimeInterpreter<'mir, 'tcx> {
    pub steps_remaining: usize,
    pub(crate) stack: Vec<Frame<'mir, 'tcx, AllocId, ()>>,
    pub(super) can_access_statics: bool,
}

Extra machine state for CTFE, and the Machine instance

Fields

steps_remaining: usize

For now, the number of terminators that can be evaluated before we throw a resource exhaustion error.

Setting this to 0 disables the limit and allows the interpreter to run forever.

stack: Vec<Frame<'mir, 'tcx, AllocId, ()>>

The virtual call stack.

can_access_statics: bool

We need to make sure consts never point to anything mutable, even recursively. That is relied on for pattern matching on consts with references. To achieve this, two pieces have to work together:

• Interning makes everything outside of statics immutable.
• Pointers to allocations inside of statics can never leak outside, to a non-static global. This boolean here controls the second part.

Implementations

impl<'mir, 'tcx> CompileTimeInterpreter<'mir, 'tcx>

pub(super) fn new(const_eval_limit: Limit, can_access_statics: bool) -> Self

Trait Implementations

impl<'mir, 'tcx> Machine<'mir, 'tcx> for CompileTimeInterpreter<'mir, 'tcx>

type PointerTag = AllocId

Pointers are “tagged” with provenance information; typically the AllocId they belong to.

type TagExtra = ()

When getting the AllocId of a pointer, some extra data is also obtained from the tag that is passed to memory access hooks so they can do things with it.

type ExtraFnVal = !

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 MemoryMap = HashMap<AllocId, (MemoryKind<MemoryKind>, Allocation<AllocId, ()>), BuildHasherDefault<FxHasher>>

Memory’s allocation map

const GLOBAL_KIND: Option<Self::MemoryKind> = None

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.

type AllocExtra = ()

Extra data stored in every allocation.

type FrameExtra = ()

Extra data stored in every call frame.

fn enforce_alignment(_ecx: &InterpCx<'mir, 'tcx, Self>) -> bool

Whether memory accesses should be alignment-checked.

fn force_int_for_alignment_check(_ecx: &InterpCx<'mir, 'tcx, Self>) -> 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 enforce_validity(_ecx: &InterpCx<'mir, 'tcx, Self>) -> bool

Whether to enforce the validity invariant

fn enforce_number_init(_ecx: &InterpCx<'mir, 'tcx, Self>) -> bool

Whether to enforce integers and floats being initialized.

fn enforce_number_no_provenance(_ecx: &InterpCx<'mir, 'tcx, Self>) -> bool

Whether to enforce integers and floats not having provenance.

fn checked_binop_checks_overflow(_ecx: &InterpCx<'mir, 'tcx, Self>) -> bool

Whether CheckedBinOp MIR statements should actually check for overflow.

fn call_extra_fn(
    _ecx: &mut InterpCx<'mir, 'tcx, Self>,
    fn_val: !,
    _abi: CallAbi,
    _args: &[OpTy<'tcx>],
    _destination: &PlaceTy<'tcx, Self::PointerTag>,
    _target: Option<BasicBlock>,
    _unwind: StackPopUnwind
) -> InterpResult<'tcx>

Execute fn_val. It is the hook’s responsibility to advance the instruction pointer as appropriate.

fn init_allocation_extra<'b>(
    _ecx: &InterpCx<'mir, 'tcx, Self>,
    _id: AllocId,
    alloc: Cow<'b, Allocation>,
    _kind: Option<MemoryKind<Self::MemoryKind>>
) -> InterpResult<'tcx, Cow<'b, Allocation<Self::PointerTag>>>

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.

fn extern_static_base_pointer(
    ecx: &InterpCx<'mir, 'tcx, Self>,
    def_id: DefId
) -> InterpResult<'tcx, Pointer>

Return the root pointer for the given extern static.

fn tag_alloc_base_pointer(
    _ecx: &InterpCx<'mir, 'tcx, Self>,
    ptr: Pointer<AllocId>
) -> Pointer<AllocId>

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.

fn ptr_from_addr_transmute(
    _ecx: &InterpCx<'mir, 'tcx, Self>,
    addr: u64
) -> Pointer<Option<AllocId>>

Hook for returning a pointer from a transmute-like operation on an addr. This is only needed to support Miri’s (unsound) “allow-ptr-int-transmute” flag.

fn ptr_from_addr_cast(
    _ecx: &InterpCx<'mir, 'tcx, Self>,
    addr: u64
) -> InterpResult<'tcx, Pointer<Option<AllocId>>>

“Int-to-pointer cast”

fn ptr_get_alloc(
    _ecx: &InterpCx<'mir, 'tcx, Self>,
    ptr: Pointer<AllocId>
) -> Option<(AllocId, Size, Self::TagExtra)>

Convert a pointer with provenance into an allocation-offset pair and extra provenance info.

type MemoryKind = MemoryKind

Additional memory kinds a machine wishes to distinguish from the builtin ones

const PANIC_ON_ALLOC_FAIL: bool = false

Should the machine panic on allocation failures?

fn load_mir(
    ecx: &InterpCx<'mir, 'tcx, Self>,
    instance: InstanceDef<'tcx>
) -> InterpResult<'tcx, &'tcx Body<'tcx>>

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 find_mir_or_eval_fn(
    ecx: &mut InterpCx<'mir, 'tcx, Self>,
    instance: Instance<'tcx>,
    _abi: CallAbi,
    args: &[OpTy<'tcx>],
    _dest: &PlaceTy<'tcx>,
    _ret: Option<BasicBlock>,
    _unwind: StackPopUnwind
) -> InterpResult<'tcx, Option<(&'mir Body<'tcx>, Instance<'tcx>)>>

Entry point to all function calls.

fn call_intrinsic(
    ecx: &mut InterpCx<'mir, 'tcx, Self>,
    instance: Instance<'tcx>,
    args: &[OpTy<'tcx>],
    dest: &PlaceTy<'tcx, Self::PointerTag>,
    target: Option<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 assert_panic(
    ecx: &mut InterpCx<'mir, 'tcx, Self>,
    msg: &AssertMessage<'tcx>,
    _unwind: Option<BasicBlock>
) -> InterpResult<'tcx>

Called to evaluate Assert MIR terminators that trigger a panic.

fn abort(
    _ecx: &mut InterpCx<'mir, 'tcx, Self>,
    msg: String
) -> InterpResult<'tcx, !>

Called to evaluate Abort MIR terminator.

fn binary_ptr_op(
    _ecx: &InterpCx<'mir, 'tcx, Self>,
    _bin_op: BinOp,
    _left: &ImmTy<'tcx>,
    _right: &ImmTy<'tcx>
) -> InterpResult<'tcx, (Scalar, bool, Ty<'tcx>)>

Called for all binary operations where the LHS has pointer type.

fn before_terminator(ecx: &mut InterpCx<'mir, 'tcx, Self>) -> InterpResult<'tcx>

Called before a basic block terminator is executed. You can use this to detect endlessly running programs.

fn expose_ptr(
    _ecx: &mut InterpCx<'mir, 'tcx, Self>,
    _ptr: Pointer<AllocId>
) -> InterpResult<'tcx>

Marks a pointer as exposed, allowing it’s provenance to be recovered. “Pointer-to-int cast”

fn init_frame_extra(
    ecx: &mut InterpCx<'mir, 'tcx, Self>,
    frame: Frame<'mir, 'tcx>
) -> InterpResult<'tcx, Frame<'mir, 'tcx>>

Called immediately before a new stack frame gets pushed.

fn stack<'a>(
    ecx: &'a InterpCx<'mir, 'tcx, Self>
) -> &'a [Frame<'mir, 'tcx, Self::PointerTag, Self::FrameExtra>]

Borrow the current thread’s stack.

fn stack_mut<'a>(
    ecx: &'a mut InterpCx<'mir, 'tcx, Self>
) -> &'a mut Vec<Frame<'mir, 'tcx, Self::PointerTag, Self::FrameExtra>>

Mutably borrow the current thread’s stack.

fn before_access_global(
    _tcx: TyCtxt<'tcx>,
    machine: &Self,
    alloc_id: AllocId,
    alloc: ConstAllocation<'tcx>,
    static_def_id: Option<DefId>,
    is_write: bool
) -> InterpResult<'tcx>

Called before a global allocation is accessed. def_id is Some if this is the “lazy” allocation of a static.

fn enforce_abi(_ecx: &InterpCx<'mir, 'tcx, Self>) -> bool

Whether function calls should be ABI-checked.

fn access_local<'a>(
    frame: &'a Frame<'mir, 'tcx, Self::PointerTag, Self::FrameExtra>,
    local: Local
) -> InterpResult<'tcx, &'a Operand<Self::PointerTag>> where
    'tcx: 'mir, 

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.

fn access_local_mut<'a>(
    ecx: &'a mut InterpCx<'mir, 'tcx, Self>,
    frame: usize,
    local: Local
) -> InterpResult<'tcx, &'a mut Operand<Self::PointerTag>> where
    'tcx: 'mir, 

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.

fn thread_local_static_base_pointer(
    _ecx: &mut InterpCx<'mir, 'tcx, Self>,
    def_id: DefId
) -> InterpResult<'tcx, Pointer<Self::PointerTag>>

Return the AllocId for the given thread-local static in the current thread.

fn memory_read(
    _tcx: TyCtxt<'tcx>,
    _machine: &Self,
    _alloc_extra: &Self::AllocExtra,
    _tag: (AllocId, Self::TagExtra),
    _range: AllocRange
) -> InterpResult<'tcx>

Hook for performing extra checks on a memory read access.

fn memory_written(
    _tcx: TyCtxt<'tcx>,
    _machine: &mut Self,
    _alloc_extra: &mut Self::AllocExtra,
    _tag: (AllocId, Self::TagExtra),
    _range: AllocRange
) -> InterpResult<'tcx>

Hook for performing extra checks on a memory write access.

fn memory_deallocated(
    _tcx: TyCtxt<'tcx>,
    _machine: &mut Self,
    _alloc_extra: &mut Self::AllocExtra,
    _tag: (AllocId, Self::TagExtra),
    _range: AllocRange
) -> InterpResult<'tcx>

Hook for performing extra operations on a memory deallocation.

fn retag(
    _ecx: &mut InterpCx<'mir, 'tcx, Self>,
    _kind: RetagKind,
    _place: &PlaceTy<'tcx, Self::PointerTag>
) -> InterpResult<'tcx>

Executes a retagging operation.

fn after_stack_push(_ecx: &mut InterpCx<'mir, 'tcx, Self>) -> InterpResult<'tcx>

Called immediately after a stack frame got pushed and its locals got initialized.

fn after_stack_pop(
    _ecx: &mut InterpCx<'mir, 'tcx, Self>,
    _frame: Frame<'mir, 'tcx, Self::PointerTag, Self::FrameExtra>,
    unwinding: bool
) -> InterpResult<'tcx, StackPopJump>

Called immediately after a stack frame got popped, but before jumping back to the caller. The locals have already been destroyed!

Layout

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain repr(...) attributes. Please see the Rust Reference’s “Type Layout” chapter for details on type layout guarantees.

Size: 40 bytes