Rollup merge of #71738 - RalfJung:pointer-no-alloc-id, r=oli-obk

remove AllocId generalization of Pointer

This was only needed for the "snapshot" machinery, which is gone.

r? @oli-obk

src/librustc_middle/mir/interpret/pointer.rs

@@ -75,18 +75,14 @@ pub trait PointerArithmetic: HasDataLayout {
 
 impl<T: HasDataLayout> PointerArithmetic for T {}
 
-/// `Pointer` is generic over the type that represents a reference to `Allocation`s,
-/// thus making it possible for the most convenient representation to be used in
-/// each context.
+/// Represents a pointer in the Miri engine.
 ///
-/// Defaults to the index based and loosely coupled `AllocId`.
-///
-/// `Pointer` is also generic over the `Tag` associated with each pointer,
+/// `Pointer` is generic over the `Tag` associated with each pointer,
 /// which is used to do provenance tracking during execution.
 #[derive(Copy, Clone, Eq, PartialEq, Ord, PartialOrd, RustcEncodable, RustcDecodable, Hash)]
 #[derive(HashStable)]
-pub struct Pointer<Tag = (), Id = AllocId> {
-    pub alloc_id: Id,
+pub struct Pointer<Tag = ()> {
+    pub alloc_id: AllocId,
     pub offset: Size,
     pub tag: Tag,
 }
@@ -97,7 +93,7 @@ static_assert_size!(Pointer, 16);
 // all the Miri types.
 // We have to use `Debug` output for the tag, because `()` does not implement
 // `Display` so we cannot specialize that.
-impl<Tag: fmt::Debug, Id: fmt::Debug> fmt::Debug for Pointer<Tag, Id> {
+impl<Tag: fmt::Debug> fmt::Debug for Pointer<Tag> {
     default fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         if f.alternate() {
             write!(f, "{:#?}+0x{:x}[{:?}]", self.alloc_id, self.offset.bytes(), self.tag)
@@ -107,7 +103,7 @@ impl<Tag: fmt::Debug, Id: fmt::Debug> fmt::Debug for Pointer<Tag, Id> {
     }
 }
 // Specialization for no tag
-impl<Id: fmt::Debug> fmt::Debug for Pointer<(), Id> {
+impl fmt::Debug for Pointer<()> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         if f.alternate() {
             write!(f, "{:#?}+0x{:x}", self.alloc_id, self.offset.bytes())

src/librustc_middle/mir/interpret/value.rs

@@ -89,7 +89,7 @@ impl<'tcx> ConstValue<'tcx> {
 /// of a simple value or a pointer into another `Allocation`
 #[derive(Clone, Copy, Eq, PartialEq, Ord, PartialOrd, RustcEncodable, RustcDecodable, Hash)]
 #[derive(HashStable)]
-pub enum Scalar<Tag = (), Id = AllocId> {
+pub enum Scalar<Tag = ()> {
     /// The raw bytes of a simple value.
     Raw {
         /// The first `size` bytes of `data` are the value.
@@ -101,7 +101,7 @@ pub enum Scalar<Tag = (), Id = AllocId> {
     /// A pointer into an `Allocation`. An `Allocation` in the `memory` module has a list of
     /// relocations, but a `Scalar` is only large enough to contain one, so we just represent the
     /// relocation and its associated offset together as a `Pointer` here.
-    Ptr(Pointer<Tag, Id>),
+    Ptr(Pointer<Tag>),
 }
 
 #[cfg(target_arch = "x86_64")]
@@ -109,7 +109,7 @@ static_assert_size!(Scalar, 24);
 
 // We want the `Debug` output to be readable as it is used by `derive(Debug)` for
 // all the Miri types.
-impl<Tag: fmt::Debug, Id: fmt::Debug> fmt::Debug for Scalar<Tag, Id> {
+impl<Tag: fmt::Debug> fmt::Debug for Scalar<Tag> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
             Scalar::Ptr(ptr) => write!(f, "{:?}", ptr),
@@ -542,8 +542,8 @@ impl<Tag> From<Pointer<Tag>> for Scalar<Tag> {
 }
 
 #[derive(Clone, Copy, Eq, PartialEq, RustcEncodable, RustcDecodable, HashStable, Hash)]
-pub enum ScalarMaybeUndef<Tag = (), Id = AllocId> {
-    Scalar(Scalar<Tag, Id>),
+pub enum ScalarMaybeUndef<Tag = ()> {
+    Scalar(Scalar<Tag>),
     Undef,
 }
 
@@ -563,7 +563,7 @@ impl<Tag> From<Pointer<Tag>> for ScalarMaybeUndef<Tag> {
 
 // We want the `Debug` output to be readable as it is used by `derive(Debug)` for
 // all the Miri types.
-impl<Tag: fmt::Debug, Id: fmt::Debug> fmt::Debug for ScalarMaybeUndef<Tag, Id> {
+impl<Tag: fmt::Debug> fmt::Debug for ScalarMaybeUndef<Tag> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
             ScalarMaybeUndef::Undef => write!(f, "<uninitialized>"),

src/librustc_mir/interpret/eval_context.rs

@@ -11,7 +11,7 @@ use rustc_macros::HashStable;
 use rustc_middle::ich::StableHashingContext;
 use rustc_middle::mir;
 use rustc_middle::mir::interpret::{
-    sign_extend, truncate, AllocId, FrameInfo, GlobalId, InterpResult, Pointer, Scalar,
+    sign_extend, truncate, FrameInfo, GlobalId, InterpResult, Pointer, Scalar,
 };
 use rustc_middle::ty::layout::{self, TyAndLayout};
 use rustc_middle::ty::{
@@ -103,8 +103,8 @@ pub enum StackPopCleanup {
 
 /// State of a local variable including a memoized layout
 #[derive(Clone, PartialEq, Eq, HashStable)]
-pub struct LocalState<'tcx, Tag = (), Id = AllocId> {
-    pub value: LocalValue<Tag, Id>,
+pub struct LocalState<'tcx, Tag = ()> {
+    pub value: LocalValue<Tag>,
     /// Don't modify if `Some`, this is only used to prevent computing the layout twice
     #[stable_hasher(ignore)]
     pub layout: Cell<Option<TyAndLayout<'tcx>>>,
@@ -112,7 +112,7 @@ pub struct LocalState<'tcx, Tag = (), Id = AllocId> {
 
 /// Current value of a local variable
 #[derive(Copy, Clone, PartialEq, Eq, Debug, HashStable)] // Miri debug-prints these
-pub enum LocalValue<Tag = (), Id = AllocId> {
+pub enum LocalValue<Tag = ()> {
     /// This local is not currently alive, and cannot be used at all.
     Dead,
     /// This local is alive but not yet initialized. It can be written to
@@ -125,7 +125,7 @@ pub enum LocalValue<Tag = (), Id = AllocId> {
     /// This is an optimization over just always having a pointer here;
     /// we can thus avoid doing an allocation when the local just stores
     /// immediate values *and* never has its address taken.
-    Live(Operand<Tag, Id>),
+    Live(Operand<Tag>),
 }
 
 impl<'tcx, Tag: Copy + 'static> LocalState<'tcx, Tag> {

src/librustc_mir/interpret/operand.rs

@@ -15,8 +15,8 @@ use rustc_target::abi::{Abi, DiscriminantKind, HasDataLayout, Integer, LayoutOf,
 use rustc_target::abi::{VariantIdx, Variants};
 
 use super::{
-    from_known_layout, sign_extend, truncate, AllocId, ConstValue, GlobalId, InterpCx,
-    InterpResult, MPlaceTy, Machine, MemPlace, Place, PlaceTy, Pointer, Scalar, ScalarMaybeUndef,
+    from_known_layout, sign_extend, truncate, ConstValue, GlobalId, InterpCx, InterpResult,
+    MPlaceTy, Machine, MemPlace, Place, PlaceTy, Pointer, Scalar, ScalarMaybeUndef,
 };
 
 /// An `Immediate` represents a single immediate self-contained Rust value.
@@ -27,9 +27,9 @@ use super::{
 /// In particular, thanks to `ScalarPair`, arithmetic operations and casts can be entirely
 /// defined on `Immediate`, and do not have to work with a `Place`.
 #[derive(Copy, Clone, Debug, PartialEq, Eq, HashStable, Hash)]
-pub enum Immediate<Tag = (), Id = AllocId> {
-    Scalar(ScalarMaybeUndef<Tag, Id>),
-    ScalarPair(ScalarMaybeUndef<Tag, Id>, ScalarMaybeUndef<Tag, Id>),
+pub enum Immediate<Tag = ()> {
+    Scalar(ScalarMaybeUndef<Tag>),
+    ScalarPair(ScalarMaybeUndef<Tag>, ScalarMaybeUndef<Tag>),
 }
 
 impl<Tag> From<ScalarMaybeUndef<Tag>> for Immediate<Tag> {
@@ -145,9 +145,9 @@ impl<'tcx, Tag> ::std::ops::Deref for ImmTy<'tcx, Tag> {
 /// or still in memory. The latter is an optimization, to delay reading that chunk of
 /// memory and to avoid having to store arbitrary-sized data here.
 #[derive(Copy, Clone, Debug, PartialEq, Eq, HashStable, Hash)]
-pub enum Operand<Tag = (), Id = AllocId> {
-    Immediate(Immediate<Tag, Id>),
-    Indirect(MemPlace<Tag, Id>),
+pub enum Operand<Tag = ()> {
+    Immediate(Immediate<Tag>),
+    Indirect(MemPlace<Tag>),
 }
 
 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]

src/librustc_mir/interpret/place.rs

@@ -20,9 +20,9 @@ use super::{
 
 #[derive(Copy, Clone, Debug, Hash, PartialEq, Eq, HashStable)]
 /// Information required for the sound usage of a `MemPlace`.
-pub enum MemPlaceMeta<Tag = (), Id = AllocId> {
+pub enum MemPlaceMeta<Tag = ()> {
     /// The unsized payload (e.g. length for slices or vtable pointer for trait objects).
-    Meta(Scalar<Tag, Id>),
+    Meta(Scalar<Tag>),
     /// `Sized` types or unsized `extern type`
     None,
     /// The address of this place may not be taken. This protects the `MemPlace` from coming from
@@ -32,8 +32,8 @@ pub enum MemPlaceMeta<Tag = (), Id = AllocId> {
     Poison,
 }
 
-impl<Tag, Id> MemPlaceMeta<Tag, Id> {
-    pub fn unwrap_meta(self) -> Scalar<Tag, Id> {
+impl<Tag> MemPlaceMeta<Tag> {
+    pub fn unwrap_meta(self) -> Scalar<Tag> {
         match self {
             Self::Meta(s) => s,
             Self::None | Self::Poison => {
@@ -47,9 +47,7 @@ impl<Tag, Id> MemPlaceMeta<Tag, Id> {
             Self::None | Self::Poison => false,
         }
     }
-}
 
-impl<Tag> MemPlaceMeta<Tag> {
     pub fn erase_tag(self) -> MemPlaceMeta<()> {
         match self {
             Self::Meta(s) => MemPlaceMeta::Meta(s.erase_tag()),
@@ -60,22 +58,22 @@ impl<Tag> MemPlaceMeta<Tag> {
 }
 
 #[derive(Copy, Clone, Debug, Hash, PartialEq, Eq, HashStable)]
-pub struct MemPlace<Tag = (), Id = AllocId> {
+pub struct MemPlace<Tag = ()> {
     /// A place may have an integral pointer for ZSTs, and since it might
     /// be turned back into a reference before ever being dereferenced.
     /// However, it may never be undef.
-    pub ptr: Scalar<Tag, Id>,
+    pub ptr: Scalar<Tag>,
     pub align: Align,
     /// Metadata for unsized places. Interpretation is up to the type.
     /// Must not be present for sized types, but can be missing for unsized types
     /// (e.g., `extern type`).
-    pub meta: MemPlaceMeta<Tag, Id>,
+    pub meta: MemPlaceMeta<Tag>,
 }
 
 #[derive(Copy, Clone, Debug, Hash, PartialEq, Eq, HashStable)]
-pub enum Place<Tag = (), Id = AllocId> {
+pub enum Place<Tag = ()> {
     /// A place referring to a value allocated in the `Memory` system.
-    Ptr(MemPlace<Tag, Id>),
+    Ptr(MemPlace<Tag>),
 
     /// To support alloc-free locals, we are able to write directly to a local.
     /// (Without that optimization, we'd just always be a `MemPlace`.)