Struct rustc_mir::transform::const_prop::ConstPropMachine

pub(in transform::const_prop) struct ConstPropMachine<'mir, 'tcx> {
    stack: Vec<Frame<'mir, 'tcx, (), ()>>,
    written_only_inside_own_block_locals: FxHashSet<Local>,
    only_propagate_inside_block_locals: BitSet<Local>,
    can_const_prop: IndexVec<Local, ConstPropMode>,
}

Fields

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

The virtual call stack.

written_only_inside_own_block_locals: FxHashSet<Local>

OnlyInsideOwnBlock locals that were written in the current block get erased at the end.

only_propagate_inside_block_locals: BitSet<Local>

Locals that need to be cleared after every block terminates.

can_const_prop: IndexVec<Local, ConstPropMode>

Implementations

impl<'mir, 'tcx> ConstPropMachine<'mir, 'tcx>

pub(in transform::const_prop) fn new(
    only_propagate_inside_block_locals: BitSet<Local>,
    can_const_prop: IndexVec<Local, ConstPropMode>
) -> Self

Trait Implementations

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

type PointerTag = ()

Tag tracked alongside every pointer. This is used to implement "Stacked Borrows" https://www.ralfj.de/blog/2018/08/07/stacked-borrows.html. The default() is used for pointers to consts, statics, vtables and functions. The Debug formatting is used for displaying pointers; we cannot use Display as () does not implement that, but it should be "nice" output.

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 MemoryKind = !

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

type MemoryMap = FxHashMap<AllocId, (MemoryKind<!>, Allocation)>

Memory's allocation map

pub const GLOBAL_KIND: Option<!>

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.

pub fn enforce_alignment(_memory_extra: &Self::MemoryExtra) -> bool

Whether memory accesses should be alignment-checked.

pub fn force_int_for_alignment_check(_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.

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

Whether to enforce the validity invariant

pub fn call_extra_fn(
    _ecx: &mut InterpCx<'mir, 'tcx, Self>,
    fn_val: !,
    _args: &[OpTy<'tcx>],
    _ret: Option<(PlaceTy<'tcx>, BasicBlock)>,
    _unwind: Option<BasicBlock>
) -> InterpResult<'tcx>

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

pub fn init_allocation_extra<'b>(
    _memory_extra: &Self::MemoryExtra,
    _id: AllocId,
    alloc: Cow<'b, Allocation>,
    _kind: Option<MemoryKind<!>>
) -> (Cow<'b, Allocation<Self::PointerTag>>, 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.

pub fn tag_global_base_pointer(
    _memory_extra: &Self::MemoryExtra,
    _id: AllocId
) -> Self::PointerTag

Return the "base" tag for the given global allocation: the one that is used for direct accesses to this static/const/fn allocation. If id is not a global allocation, this will return an unusable tag (i.e., accesses will be UB)!

type MemoryExtra = ()

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.

pub fn find_mir_or_eval_fn(
    _ecx: &mut InterpCx<'mir, 'tcx, Self>,
    _instance: Instance<'tcx>,
    _args: &[OpTy<'tcx>],
    _ret: Option<(PlaceTy<'tcx>, BasicBlock)>,
    _unwind: Option<BasicBlock>
) -> InterpResult<'tcx, Option<&'mir Body<'tcx>>>

Entry point to all function calls.

pub fn call_intrinsic(
    _ecx: &mut InterpCx<'mir, 'tcx, Self>,
    _instance: Instance<'tcx>,
    _args: &[OpTy<'tcx>],
    _ret: Option<(PlaceTy<'tcx>, BasicBlock)>,
    _unwind: Option<BasicBlock>
) -> InterpResult<'tcx>

Directly process an intrinsic without pushing a stack frame. It is the hook's responsibility to advance the instruction pointer as appropriate.

pub 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.

pub fn ptr_to_int(
    _mem: &Memory<'mir, 'tcx, Self>,
    _ptr: Pointer
) -> InterpResult<'tcx, u64>

pub 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.

pub fn box_alloc(
    _ecx: &mut InterpCx<'mir, 'tcx, Self>,
    _dest: PlaceTy<'tcx>
) -> InterpResult<'tcx>

Heap allocations via the box keyword.

pub fn access_local(
    _ecx: &InterpCx<'mir, 'tcx, Self>,
    frame: &Frame<'mir, 'tcx, Self::PointerTag, Self::FrameExtra>,
    local: Local
) -> InterpResult<'tcx, InterpOperand<Self::PointerTag>>

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.

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

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.

pub fn before_access_global(
    _memory_extra: &(),
    _alloc_id: AllocId,
    allocation: &Allocation<Self::PointerTag, Self::AllocExtra>,
    _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.

pub 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.

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

Borrow the current thread's stack.

pub 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.

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

Called to evaluate Abort MIR terminator.

pub 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.

pub fn thread_local_static_alloc_id(
    _ecx: &mut InterpCx<'mir, 'tcx, Self>,
    def_id: DefId
) -> InterpResult<'tcx, AllocId>

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

pub fn extern_static_alloc_id(
    mem: &Memory<'mir, 'tcx, Self>,
    def_id: DefId
) -> InterpResult<'tcx, AllocId>

Return the AllocId backing the given extern static.

pub fn before_deallocation(
    _memory_extra: &mut Self::MemoryExtra,
    _id: AllocId
) -> InterpResult<'tcx>

Called to notify the machine before a deallocation occurs.

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

Executes a retagging operation

pub 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.

pub 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.

pub fn int_to_ptr(
    _mem: &Memory<'mir, 'tcx, Self>,
    int: u64
) -> InterpResult<'tcx, Pointer<Self::PointerTag>>