Alignment of the bytes of Allocation to match align parameter

compiler/rustc_const_eval/src/interpret/machine.rs

@@ -14,7 +14,7 @@ use rustc_target::abi::Size;
 use rustc_target::spec::abi::Abi as CallAbi;
 
 use super::{
-    AllocId, AllocRange, Allocation, ConstAllocation, Frame, ImmTy, InterpCx, InterpResult,
+    AllocId, AllocRange, Allocation, AllocBytes, ConstAllocation, Frame, ImmTy, InterpCx, InterpResult,
     MemoryKind, OpTy, Operand, PlaceTy, Pointer, Provenance, Scalar, StackPopUnwind,
 };
 
@@ -103,10 +103,13 @@ pub trait Machine<'mir, 'tcx>: Sized {
     /// Extra data stored in every allocation.
     type AllocExtra: Debug + Clone + 'static;
 
+    /// Type for the bytes of the allocation.
+    type Bytes: AllocBytes + 'static;
+
     /// Memory's allocation map
     type MemoryMap: AllocMap<
             AllocId,
-            (MemoryKind<Self::MemoryKind>, Allocation<Self::Provenance, Self::AllocExtra>),
+            (MemoryKind<Self::MemoryKind>, Allocation<Self::Provenance, Self::AllocExtra, Self::Bytes>),
         > + Default
         + Clone;
 
@@ -322,7 +325,7 @@ pub trait Machine<'mir, 'tcx>: Sized {
         id: AllocId,
         alloc: Cow<'b, Allocation>,
         kind: Option<MemoryKind<Self::MemoryKind>>,
-    ) -> InterpResult<'tcx, Cow<'b, Allocation<Self::Provenance, Self::AllocExtra>>>;
+    ) -> InterpResult<'tcx, Cow<'b, Allocation<Self::Provenance, Self::AllocExtra, Self::Bytes>>>;
 
     fn eval_inline_asm(
         _ecx: &mut InterpCx<'mir, 'tcx, Self>,
@@ -431,6 +434,7 @@ pub macro compile_time_machine(<$mir: lifetime, $tcx: lifetime>) {
 
     type AllocExtra = ();
     type FrameExtra = ();
+    type Bytes = Box<[u8]>;
 
     #[inline(always)]
     fn use_addr_for_alignment_check(_ecx: &InterpCx<$mir, $tcx, Self>) -> bool {

compiler/rustc_const_eval/src/interpret/memory.rs

@@ -19,8 +19,9 @@ use rustc_middle::ty::{self, Instance, ParamEnv, Ty, TyCtxt};
 use rustc_target::abi::{Align, HasDataLayout, Size};
 
 use super::{
-    alloc_range, AllocId, AllocMap, AllocRange, Allocation, CheckInAllocMsg, GlobalAlloc, InterpCx,
-    InterpResult, Machine, MayLeak, Pointer, PointerArithmetic, Provenance, Scalar,
+    alloc_range, AllocBytes, AllocId, AllocMap, AllocRange, Allocation, CheckInAllocMsg,
+    GlobalAlloc, InterpCx, InterpResult, Machine, MayLeak, Pointer, PointerArithmetic, Provenance,
+    Scalar,
 };
 
 #[derive(Debug, PartialEq, Copy, Clone)]
@@ -112,16 +113,16 @@ pub struct Memory<'mir, 'tcx, M: Machine<'mir, 'tcx>> {
 /// A reference to some allocation that was already bounds-checked for the given region
 /// and had the on-access machine hooks run.
 #[derive(Copy, Clone)]
-pub struct AllocRef<'a, 'tcx, Prov, Extra> {
-    alloc: &'a Allocation<Prov, Extra>,
+pub struct AllocRef<'a, 'tcx, Prov, Extra, Bytes: AllocBytes = Box<[u8]>> {
+    alloc: &'a Allocation<Prov, Extra, Bytes>,
     range: AllocRange,
     tcx: TyCtxt<'tcx>,
     alloc_id: AllocId,
 }
 /// A reference to some allocation that was already bounds-checked for the given region
 /// and had the on-access machine hooks run.
-pub struct AllocRefMut<'a, 'tcx, Prov, Extra> {
-    alloc: &'a mut Allocation<Prov, Extra>,
+pub struct AllocRefMut<'a, 'tcx, Prov, Extra, Bytes: AllocBytes = Box<[u8]>> {
+    alloc: &'a mut Allocation<Prov, Extra, Bytes>,
     range: AllocRange,
     tcx: TyCtxt<'tcx>,
     alloc_id: AllocId,
@@ -475,7 +476,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         &self,
         id: AllocId,
         is_write: bool,
-    ) -> InterpResult<'tcx, Cow<'tcx, Allocation<M::Provenance, M::AllocExtra>>> {
+    ) -> InterpResult<'tcx, Cow<'tcx, Allocation<M::Provenance, M::AllocExtra, M::Bytes>>> {
         let (alloc, def_id) = match self.tcx.try_get_global_alloc(id) {
             Some(GlobalAlloc::Memory(mem)) => {
                 // Memory of a constant or promoted or anonymous memory referenced by a static.
@@ -517,14 +518,26 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         )
     }
 
+    /// Get the base address for the bytes in an `Allocation` specified by the
+    /// `AllocID` passed in; error if no such allocation exists. The address will
+    /// be exposed (on the host system!).
+    ///
+    /// It is up to the caller to take sufficient care when using this address:
+    /// there could be provenance or uninit memory in there, and other memory
+    /// accesses could invalidate the exposed pointer.
+    pub fn expose_alloc_base_addr(&self, id: AllocId) -> InterpResult<'tcx, usize> {
+        let alloc = self.get_alloc_raw(id)?;
+        Ok(alloc.expose_base_addr())
+    }
+
     /// Gives raw access to the `Allocation`, without bounds or alignment checks.
     /// The caller is responsible for calling the access hooks!
     ///
     /// You almost certainly want to use `get_ptr_alloc`/`get_ptr_alloc_mut` instead.
     fn get_alloc_raw(
         &self,
         id: AllocId,
-    ) -> InterpResult<'tcx, &Allocation<M::Provenance, M::AllocExtra>> {
+    ) -> InterpResult<'tcx, &Allocation<M::Provenance, M::AllocExtra, M::Bytes>> {
         // The error type of the inner closure here is somewhat funny.  We have two
         // ways of "erroring": An actual error, or because we got a reference from
         // `get_global_alloc` that we can actually use directly without inserting anything anywhere.
@@ -560,7 +573,8 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         ptr: Pointer<Option<M::Provenance>>,
         size: Size,
         align: Align,
-    ) -> InterpResult<'tcx, Option<AllocRef<'a, 'tcx, M::Provenance, M::AllocExtra>>> {
+    ) -> InterpResult<'tcx, Option<AllocRef<'a, 'tcx, M::Provenance, M::AllocExtra, M::Bytes>>>
+    {
         let align = M::enforce_alignment(self).then_some(align);
         let ptr_and_alloc = self.check_and_deref_ptr(
             ptr,
@@ -603,7 +617,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
     fn get_alloc_raw_mut(
         &mut self,
         id: AllocId,
-    ) -> InterpResult<'tcx, (&mut Allocation<M::Provenance, M::AllocExtra>, &mut M)> {
+    ) -> InterpResult<'tcx, (&mut Allocation<M::Provenance, M::AllocExtra, M::Bytes>, &mut M)> {
         // We have "NLL problem case #3" here, which cannot be worked around without loss of
         // efficiency even for the common case where the key is in the map.
         // <https://rust-lang.github.io/rfcs/2094-nll.html#problem-case-3-conditional-control-flow-across-functions>
@@ -632,7 +646,8 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         ptr: Pointer<Option<M::Provenance>>,
         size: Size,
         align: Align,
-    ) -> InterpResult<'tcx, Option<AllocRefMut<'a, 'tcx, M::Provenance, M::AllocExtra>>> {
+    ) -> InterpResult<'tcx, Option<AllocRefMut<'a, 'tcx, M::Provenance, M::AllocExtra, M::Bytes>>>
+    {
         let parts = self.get_ptr_access(ptr, size, align)?;
         if let Some((alloc_id, offset, prov)) = parts {
             let tcx = *self.tcx;
@@ -826,12 +841,12 @@ pub struct DumpAllocs<'a, 'mir, 'tcx, M: Machine<'mir, 'tcx>> {
 
 impl<'a, 'mir, 'tcx, M: Machine<'mir, 'tcx>> std::fmt::Debug for DumpAllocs<'a, 'mir, 'tcx, M> {
     fn fmt(&self, fmt: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        // Cannot be a closure because it is generic in `Prov`, `Extra`.
-        fn write_allocation_track_relocs<'tcx, Prov: Provenance, Extra>(
+        // Cannot be a closure because it is generic in `Prov`, `Extra`, and `Bytes`.
+        fn write_allocation_track_relocs<'tcx, Prov: Provenance, Extra, Bytes: AllocBytes>(
             fmt: &mut std::fmt::Formatter<'_>,
             tcx: TyCtxt<'tcx>,
             allocs_to_print: &mut VecDeque<AllocId>,
-            alloc: &Allocation<Prov, Extra>,
+            alloc: &Allocation<Prov, Extra, Bytes>,
         ) -> std::fmt::Result {
             for alloc_id in alloc.provenance().values().filter_map(|prov| prov.get_alloc_id()) {
                 allocs_to_print.push_back(alloc_id);
@@ -898,7 +913,9 @@ impl<'a, 'mir, 'tcx, M: Machine<'mir, 'tcx>> std::fmt::Debug for DumpAllocs<'a,
 }
 
 /// Reading and writing.
-impl<'tcx, 'a, Prov: Provenance, Extra> AllocRefMut<'a, 'tcx, Prov, Extra> {
+impl<'tcx, 'a, Prov: Provenance, Extra, Bytes: AllocBytes>
+    AllocRefMut<'a, 'tcx, Prov, Extra, Bytes>
+{
     /// `range` is relative to this allocation reference, not the base of the allocation.
     pub fn write_scalar(&mut self, range: AllocRange, val: Scalar<Prov>) -> InterpResult<'tcx> {
         let range = self.range.subrange(range);
@@ -923,7 +940,7 @@ impl<'tcx, 'a, Prov: Provenance, Extra> AllocRefMut<'a, 'tcx, Prov, Extra> {
     }
 }
 
-impl<'tcx, 'a, Prov: Provenance, Extra> AllocRef<'a, 'tcx, Prov, Extra> {
+impl<'tcx, 'a, Prov: Provenance, Extra, Bytes: AllocBytes> AllocRef<'a, 'tcx, Prov, Extra, Bytes> {
     /// `range` is relative to this allocation reference, not the base of the allocation.
     pub fn read_scalar(
         &self,

compiler/rustc_const_eval/src/interpret/place.rs

@@ -339,7 +339,7 @@ where
     pub(super) fn get_place_alloc(
         &self,
         place: &MPlaceTy<'tcx, M::Provenance>,
-    ) -> InterpResult<'tcx, Option<AllocRef<'_, 'tcx, M::Provenance, M::AllocExtra>>> {
+    ) -> InterpResult<'tcx, Option<AllocRef<'_, 'tcx, M::Provenance, M::AllocExtra, M::Bytes>>> {
         assert!(!place.layout.is_unsized());
         assert!(!place.meta.has_meta());
         let size = place.layout.size;
@@ -350,7 +350,7 @@ where
     pub(super) fn get_place_alloc_mut(
         &mut self,
         place: &MPlaceTy<'tcx, M::Provenance>,
-    ) -> InterpResult<'tcx, Option<AllocRefMut<'_, 'tcx, M::Provenance, M::AllocExtra>>> {
+    ) -> InterpResult<'tcx, Option<AllocRefMut<'_, 'tcx, M::Provenance, M::AllocExtra, M::Bytes>>> {
         assert!(!place.layout.is_unsized());
         assert!(!place.meta.has_meta());
         let size = place.layout.size;

compiler/rustc_middle/src/lib.rs

@@ -23,6 +23,7 @@
 //! This API is completely unstable and subject to change.
 
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
+#![feature(maybe_uninit_write_slice)]
 #![feature(allocator_api)]
 #![feature(array_windows)]
 #![feature(assert_matches)]
@@ -59,6 +60,7 @@
 #![feature(intra_doc_pointers)]
 #![feature(yeet_expr)]
 #![feature(const_option)]
+#![feature(vec_into_raw_parts)]
 #![recursion_limit = "512"]
 #![allow(rustc::potential_query_instability)]