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Rollup merge of #129684 - Strophox:miri-pass-pointer-to-ffi, r=RalfJung

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Enable Miri to pass pointers through FFI

Following https://github.com/rust-lang/rust/pull/126787, the purpose of this PR is to now enable Miri to execute native calls that make use of pointers.

> <details>
>
> <summary> Simple example </summary>
>
> ```rust
> extern "C" {
>     fn ptr_printer(ptr: *mut i32);
> }
>
> fn main() {
>     let ptr = &mut 42 as *mut i32;
>     unsafe {
>         ptr_printer(ptr);
>     }
> }
> ```
> ```c
> void ptr_printer(int *ptr) {
>   printf("printing pointer dereference from C: %d\n", *ptr);
> }
> ```
> should now show `printing pointer dereference from C: 42`.
>
> </details>

Note that this PR does not yet implement any logic involved in updating Miri's "analysis" state (byte initialization, provenance) upon such a native call.

r? ``@RalfJung``
This commit is contained in:
Matthias Krüger 2024-08-31 20:36:25 +02:00 • committed by GitHub
commit a5fb8b90bf
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15 changed files with 260 additions and 17 deletions
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12
compiler/rustc_const_eval/src/interpret/machine.rs
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@ -362,17 +362,7 @@ pub trait Machine<'tcx>: Sized {
ecx: &InterpCx<'tcx, Self>,
id: AllocId,
alloc: &'b Allocation,
) -> InterpResult<'tcx, Cow<'b, Allocation<Self::Provenance, Self::AllocExtra, Self::Bytes>>>
{
// The default implementation does a copy; CTFE machines have a more efficient implementation
// based on their particular choice for `Provenance`, `AllocExtra`, and `Bytes`.
let kind = Self::GLOBAL_KIND
.expect("if GLOBAL_KIND is None, adjust_global_allocation must be overwritten");
let alloc = alloc.adjust_from_tcx(&ecx.tcx, |ptr| ecx.global_root_pointer(ptr))?;
let extra =
Self::init_alloc_extra(ecx, id, MemoryKind::Machine(kind), alloc.size(), alloc.align)?;
Ok(Cow::Owned(alloc.with_extra(extra)))
}
) -> InterpResult<'tcx, Cow<'b, Allocation<Self::Provenance, Self::AllocExtra, Self::Bytes>>>;
/// Initialize the extra state of an allocation.
///