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interpret: support for per-byte provenance

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This commit is contained in:
Ralf Jung 2022-11-06 13:00:09 +01:00
parent 452cf4f710
commit 2cef9e3d19
18 changed files with 506 additions and 291 deletions
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25
compiler/rustc_middle/src/mir/interpret/pointer.rs
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@ -103,8 +103,7 @@ impl<T: HasDataLayout> PointerArithmetic for T {}
/// This trait abstracts over the kind of provenance that is associated with a `Pointer`. It is
/// mostly opaque; the `Machine` trait extends it with some more operations that also have access to
/// some global state.
/// We don't actually care about this `Debug` bound (we use `Provenance::fmt` to format the entire
/// pointer), but `derive` adds some unnecessary bounds.
/// The `Debug` rendering is used to distplay bare provenance, and for the default impl of `fmt`.
pub trait Provenance: Copy + fmt::Debug {
/// Says whether the `offset` field of `Pointer`s with this provenance is the actual physical address.
/// - If `false`, the offset *must* be relative. This means the bytes representing a pointer are
@ -115,14 +114,23 @@ pub trait Provenance: Copy + fmt::Debug {
/// pointer, and implement ptr-to-int transmutation by stripping provenance.
const OFFSET_IS_ADDR: bool;
/// We also use this trait to control whether to abort execution when a pointer is being partially overwritten
/// (this avoids a separate trait in `allocation.rs` just for this purpose).
const ERR_ON_PARTIAL_PTR_OVERWRITE: bool;
/// Determines how a pointer should be printed.
///
/// Default impl is only good for when `OFFSET_IS_ADDR == true`.
fn fmt(ptr: &Pointer<Self>, f: &mut fmt::Formatter<'_>) -> fmt::Result
where
Self: Sized;
Self: Sized,
{
assert!(Self::OFFSET_IS_ADDR);
let (prov, addr) = ptr.into_parts(); // address is absolute
write!(f, "{:#x}", addr.bytes())?;
if f.alternate() {
write!(f, "{prov:#?}")?;
} else {
write!(f, "{prov:?}")?;
}
Ok(())
}
/// If `OFFSET_IS_ADDR == false`, provenance must always be able to
/// identify the allocation this ptr points to (i.e., this must return `Some`).
@ -139,9 +147,6 @@ impl Provenance for AllocId {
// so ptr-to-int casts are not possible (since we do not know the global physical offset).
const OFFSET_IS_ADDR: bool = false;
// For now, do not allow this, so that we keep our options open.
const ERR_ON_PARTIAL_PTR_OVERWRITE: bool = true;
fn fmt(ptr: &Pointer<Self>, f: &mut fmt::Formatter<'_>) -> fmt::Result {
// Forward `alternate` flag to `alloc_id` printing.
if f.alternate() {