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offset_from intrinsic: always allow pointers to point to the same address

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This commit is contained in:
Ralf Jung 2024-05-09 12:52:38 +02:00
parent 3bec61736a
commit f6c377c350
7 changed files with 67 additions and 61 deletions
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33
compiler/rustc_const_eval/src/interpret/intrinsics.rs
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@ -20,7 +20,7 @@ use super::{
err_inval, err_ub_custom, err_unsup_format, memory::MemoryKind, throw_inval, throw_ub_custom,
throw_ub_format, util::ensure_monomorphic_enough, Allocation, CheckInAllocMsg, ConstAllocation,
GlobalId, ImmTy, InterpCx, InterpResult, MPlaceTy, Machine, OpTy, Pointer, PointerArithmetic,
Scalar,
Provenance, Scalar,
};
use crate::fluent_generated as fluent;
@ -259,25 +259,28 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
// This will always return 0.
(a, b)
}
(Err(_), _) | (_, Err(_)) => {
// We managed to find a valid allocation for one pointer, but not the other.
// That means they are definitely not pointing to the same allocation.
_ if M::Provenance::OFFSET_IS_ADDR && a.addr() == b.addr() => {
// At least one of the pointers has provenance, but they also point to
// the same address so it doesn't matter; this is fine. `(0, 0)` means
// we pass all the checks below and return 0.
(0, 0)
}
// From here onwards, the pointers are definitely for different addresses
// (or we can't determine their absolute address).
(Ok((a_alloc_id, a_offset, _)), Ok((b_alloc_id, b_offset, _)))
if a_alloc_id == b_alloc_id =>
{
// Found allocation for both, and it's the same.
// Use these offsets for distance calculation.
(a_offset.bytes(), b_offset.bytes())
}
_ => {
// Not into the same allocation -- this is UB.
throw_ub_custom!(
fluent::const_eval_offset_from_different_allocations,
name = intrinsic_name,
);
}
(Ok((a_alloc_id, a_offset, _)), Ok((b_alloc_id, b_offset, _))) => {
// Found allocation for both. They must be into the same allocation.
if a_alloc_id != b_alloc_id {
throw_ub_custom!(
fluent::const_eval_offset_from_different_allocations,
name = intrinsic_name,
);
}
// Use these offsets for distance calculation.
(a_offset.bytes(), b_offset.bytes())
}
};
// Compute distance.