-use std::convert::TryFrom;
-
use log::trace;
use rustc_middle::{mir, ty::Ty};
-use rustc_target::abi::{LayoutOf, Size};
use crate::*;
) -> InterpResult<'tcx, (Scalar<Tag>, bool, Ty<'tcx>)>;
fn ptr_eq(&self, left: Scalar<Tag>, right: Scalar<Tag>) -> InterpResult<'tcx, bool>;
-
- fn pointer_offset_inbounds(
- &self,
- ptr: Scalar<Tag>,
- pointee_ty: Ty<'tcx>,
- offset: i64,
- ) -> InterpResult<'tcx, Scalar<Tag>>;
}
impl<'mir, 'tcx> EvalContextExt<'tcx> for super::MiriEvalContext<'mir, 'tcx> {
Offset => {
let pointee_ty =
left.layout.ty.builtin_deref(true).expect("Offset called on non-ptr type").ty;
- let ptr = self.pointer_offset_inbounds(
+ let ptr = self.ptr_offset_inbounds(
left.to_scalar()?,
pointee_ty,
right.to_scalar()?.to_machine_isize(self)?,
let right = self.force_bits(right, size)?;
Ok(left == right)
}
-
- /// Raises an error if the offset moves the pointer outside of its allocation.
- /// For integers, we consider each of them their own tiny allocation of size 0,
- /// so offset-by-0 is okay for them -- except for NULL, which we rule out entirely.
- fn pointer_offset_inbounds(
- &self,
- ptr: Scalar<Tag>,
- pointee_ty: Ty<'tcx>,
- offset: i64,
- ) -> InterpResult<'tcx, Scalar<Tag>> {
- let pointee_size = i64::try_from(self.layout_of(pointee_ty)?.size.bytes()).unwrap();
- let offset = offset.checked_mul(pointee_size).ok_or_else(|| {
- err_ub_format!("overflow during offset comutation for inbounds pointer arithmetic")
- })?;
- // We do this first, to rule out overflows.
- let offset_ptr = ptr.ptr_signed_offset(offset, self)?;
- // What we need to check is that starting at `min(ptr, offset_ptr)`,
- // we could do an access of size `abs(offset)`. Alignment does not matter.
- let (min_ptr, abs_offset) = if offset >= 0 {
- (ptr, u64::try_from(offset).unwrap())
- } else {
- // Negative offset.
- // If the negation overflows, the result will be negative so the try_from will fail.
- (offset_ptr, u64::try_from(-offset).unwrap())
- };
- self.memory.check_ptr_access_align(
- min_ptr,
- Size::from_bytes(abs_offset),
- None,
- CheckInAllocMsg::InboundsTest,
- )?;
- // That's it!
- Ok(offset_ptr)
- }
}