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Rollup merge of #124030 - RalfJung:adjust_alloc_base_pointer, r=oli-obk

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interpret: pass MemoryKind to adjust_alloc_base_pointer

Another puzzle piece for https://github.com/rust-lang/miri/pull/3475.

The 2nd commit renames base_pointer -> root_pointer; that's how Tree Borrows already calls them and I think the term is more clear than "base pointer". In particular, this distinguishes it from "base address", since a root pointer can point anywhere into an allocation, not just its base address.

https://github.com/rust-lang/rust/pull/124018 has been rolled up already so I couldn't add it there any more.

r? ```@oli-obk```
This commit is contained in:
Matthias Krüger 2024-04-17 18:01:38 +02:00 committed by GitHub
commit 6388167811
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GPG Key ID: B5690EEEBB952194
14 changed files with 85 additions and 65 deletions
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35
compiler/rustc_const_eval/src/interpret/machine.rs
View File

@ -288,28 +288,19 @@ pub trait Machine<'mir, 'tcx: 'mir>: Sized {
}
/// Return the `AllocId` for the given thread-local static in the current thread.
fn thread_local_static_base_pointer(
fn thread_local_static_pointer(
_ecx: &mut InterpCx<'mir, 'tcx, Self>,
def_id: DefId,
) -> InterpResult<'tcx, Pointer<Self::Provenance>> {
throw_unsup!(ThreadLocalStatic(def_id))
}
/// Return the root pointer for the given `extern static`.
fn extern_static_base_pointer(
/// Return the `AllocId` for the given `extern static`.
fn extern_static_pointer(
ecx: &InterpCx<'mir, 'tcx, Self>,
def_id: DefId,
) -> InterpResult<'tcx, Pointer<Self::Provenance>>;
/// Return a "base" pointer for the given allocation: the one that is used for direct
/// accesses to this static/const/fn allocation, or the one returned from the heap allocator.
///
/// Not called on `extern` or thread-local statics (those use the methods above).
fn adjust_alloc_base_pointer(
ecx: &InterpCx<'mir, 'tcx, Self>,
ptr: Pointer,
) -> InterpResult<'tcx, Pointer<Self::Provenance>>;
/// "Int-to-pointer cast"
fn ptr_from_addr_cast(
ecx: &InterpCx<'mir, 'tcx, Self>,
@ -336,6 +327,8 @@ pub trait Machine<'mir, 'tcx: 'mir>: Sized {
/// Called to adjust allocations to the Provenance and AllocExtra of this machine.
///
/// If `alloc` contains pointers, then they are all pointing to globals.
///
/// The way we construct allocations is to always first construct it without extra and then add
/// the extra. This keeps uniform code paths for handling both allocations created by CTFE for
/// globals, and allocations created by Miri during evaluation.
@ -354,6 +347,19 @@ pub trait Machine<'mir, 'tcx: 'mir>: Sized {
kind: Option<MemoryKind<Self::MemoryKind>>,
) -> InterpResult<'tcx, Cow<'b, Allocation<Self::Provenance, Self::AllocExtra, Self::Bytes>>>;
/// Return a "root" pointer for the given allocation: the one that is used for direct
/// accesses to this static/const/fn allocation, or the one returned from the heap allocator.
///
/// Not called on `extern` or thread-local statics (those use the methods above).
///
/// `kind` is the kind of the allocation the pointer points to; it can be `None` when
/// it's a global and `GLOBAL_KIND` is `None`.
fn adjust_alloc_root_pointer(
ecx: &InterpCx<'mir, 'tcx, Self>,
ptr: Pointer,
kind: Option<MemoryKind<Self::MemoryKind>>,
) -> InterpResult<'tcx, Pointer<Self::Provenance>>;
/// Evaluate the inline assembly.
///
/// This should take care of jumping to the next block (one of `targets`) when asm goto
@ -592,7 +598,7 @@ pub macro compile_time_machine(<$mir: lifetime, $tcx: lifetime>) {
Ok(alloc)
}
fn extern_static_base_pointer(
fn extern_static_pointer(
ecx: &InterpCx<$mir, $tcx, Self>,
def_id: DefId,
) -> InterpResult<$tcx, Pointer> {
@ -601,9 +607,10 @@ pub macro compile_time_machine(<$mir: lifetime, $tcx: lifetime>) {
}
#[inline(always)]
fn adjust_alloc_base_pointer(
fn adjust_alloc_root_pointer(
_ecx: &InterpCx<$mir, $tcx, Self>,
ptr: Pointer<CtfeProvenance>,
_kind: Option<MemoryKind<Self::MemoryKind>>,
) -> InterpResult<$tcx, Pointer<CtfeProvenance>> {
Ok(ptr)
}

18
compiler/rustc_const_eval/src/interpret/memory.rs
View File

@ -165,7 +165,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
///
/// This function can fail only if `ptr` points to an `extern static`.
#[inline]
pub fn global_base_pointer(
pub fn global_root_pointer(
&self,
ptr: Pointer<CtfeProvenance>,
) -> InterpResult<'tcx, Pointer<M::Provenance>> {
@ -178,12 +178,18 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
bug!("global memory cannot point to thread-local static")
}
Some(GlobalAlloc::Static(def_id)) if self.tcx.is_foreign_item(def_id) => {
return M::extern_static_base_pointer(self, def_id);
return M::extern_static_pointer(self, def_id);
}
None => {
assert!(
self.memory.extra_fn_ptr_map.contains_key(&alloc_id),
"{alloc_id:?} is neither global nor a function pointer"
);
}
_ => {}
}
// And we need to get the provenance.
M::adjust_alloc_base_pointer(self, ptr)
M::adjust_alloc_root_pointer(self, ptr, M::GLOBAL_KIND.map(MemoryKind::Machine))
}
pub fn fn_ptr(&mut self, fn_val: FnVal<'tcx, M::ExtraFnVal>) -> Pointer<M::Provenance> {
@ -197,9 +203,9 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
id
}
};
// Functions are global allocations, so make sure we get the right base pointer.
// Functions are global allocations, so make sure we get the right root pointer.
// We know this is not an `extern static` so this cannot fail.
self.global_base_pointer(Pointer::from(id)).unwrap()
self.global_root_pointer(Pointer::from(id)).unwrap()
}
pub fn allocate_ptr(
@ -240,7 +246,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
);
let alloc = M::adjust_allocation(self, id, Cow::Owned(alloc), Some(kind))?;
self.memory.alloc_map.insert(id, (kind, alloc.into_owned()));
M::adjust_alloc_base_pointer(self, Pointer::from(id))
M::adjust_alloc_root_pointer(self, Pointer::from(id), Some(kind))
}
pub fn reallocate_ptr(

6
compiler/rustc_const_eval/src/interpret/operand.rs
View File

@ -764,7 +764,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
// Other cases need layout.
let adjust_scalar = |scalar| -> InterpResult<'tcx, _> {
Ok(match scalar {
Scalar::Ptr(ptr, size) => Scalar::Ptr(self.global_base_pointer(ptr)?, size),
Scalar::Ptr(ptr, size) => Scalar::Ptr(self.global_root_pointer(ptr)?, size),
Scalar::Int(int) => Scalar::Int(int),
})
};
@ -772,7 +772,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
let imm = match val_val {
mir::ConstValue::Indirect { alloc_id, offset } => {
// This is const data, no mutation allowed.
let ptr = self.global_base_pointer(Pointer::new(
let ptr = self.global_root_pointer(Pointer::new(
CtfeProvenance::from(alloc_id).as_immutable(),
offset,
))?;
@ -784,7 +784,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
// This is const data, no mutation allowed.
let alloc_id = self.tcx.reserve_and_set_memory_alloc(data);
let ptr = Pointer::new(CtfeProvenance::from(alloc_id).as_immutable(), Size::ZERO);
Immediate::new_slice(self.global_base_pointer(ptr)?.into(), meta, self)
Immediate::new_slice(self.global_root_pointer(ptr)?.into(), meta, self)
}
};
Ok(OpTy { op: Operand::Immediate(imm), layout })

2
compiler/rustc_const_eval/src/interpret/place.rs
View File

@ -1010,7 +1010,7 @@ where
) -> InterpResult<'tcx, MPlaceTy<'tcx, M::Provenance>> {
// This must be an allocation in `tcx`
let _ = self.tcx.global_alloc(raw.alloc_id);
let ptr = self.global_base_pointer(Pointer::from(raw.alloc_id))?;
let ptr = self.global_root_pointer(Pointer::from(raw.alloc_id))?;
let layout = self.layout_of(raw.ty)?;
Ok(self.ptr_to_mplace(ptr.into(), layout))
}

2
compiler/rustc_const_eval/src/interpret/step.rs
View File

@ -144,7 +144,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
use rustc_middle::mir::Rvalue::*;
match *rvalue {
ThreadLocalRef(did) => {
let ptr = M::thread_local_static_base_pointer(self, did)?;
let ptr = M::thread_local_static_pointer(self, did)?;
self.write_pointer(ptr, &dest)?;
}

2
compiler/rustc_const_eval/src/interpret/traits.rs
View File

@ -28,7 +28,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
ensure_monomorphic_enough(*self.tcx, poly_trait_ref)?;
let vtable_symbolic_allocation = self.tcx.reserve_and_set_vtable_alloc(ty, poly_trait_ref);
let vtable_ptr = self.global_base_pointer(Pointer::from(vtable_symbolic_allocation))?;
let vtable_ptr = self.global_root_pointer(Pointer::from(vtable_symbolic_allocation))?;
Ok(vtable_ptr.into())
}

15
src/tools/miri/src/alloc_addresses/mod.rs
View File

@ -141,7 +141,11 @@ trait EvalContextExtPriv<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
}
}
fn addr_from_alloc_id(&self, alloc_id: AllocId) -> InterpResult<'tcx, u64> {
fn addr_from_alloc_id(
&self,
alloc_id: AllocId,
_kind: MemoryKind,
) -> InterpResult<'tcx, u64> {
let ecx = self.eval_context_ref();
let mut global_state = ecx.machine.alloc_addresses.borrow_mut();
let global_state = &mut *global_state;
@ -283,16 +287,17 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
}
/// Convert a relative (tcx) pointer to a Miri pointer.
fn ptr_from_rel_ptr(
fn adjust_alloc_root_pointer(
&self,
ptr: Pointer<CtfeProvenance>,
tag: BorTag,
kind: MemoryKind,
) -> InterpResult<'tcx, Pointer<Provenance>> {
let ecx = self.eval_context_ref();
let (prov, offset) = ptr.into_parts(); // offset is relative (AllocId provenance)
let alloc_id = prov.alloc_id();
let base_addr = ecx.addr_from_alloc_id(alloc_id)?;
let base_addr = ecx.addr_from_alloc_id(alloc_id, kind)?;
// Add offset with the right kind of pointer-overflowing arithmetic.
let dl = ecx.data_layout();
@ -314,9 +319,9 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
ecx.alloc_id_from_addr(addr.bytes())?
};
// This cannot fail: since we already have a pointer with that provenance, rel_ptr_to_addr
// This cannot fail: since we already have a pointer with that provenance, adjust_alloc_root_pointer
// must have been called in the past, so we can just look up the address in the map.
let base_addr = ecx.addr_from_alloc_id(alloc_id).unwrap();
let base_addr = *ecx.machine.alloc_addresses.borrow().base_addr.get(&alloc_id).unwrap();
// Wrapping "addr - base_addr"
#[allow(clippy::cast_possible_wrap)] // we want to wrap here

18
src/tools/miri/src/borrow_tracker/mod.rs
View File

@ -89,10 +89,10 @@ pub struct GlobalStateInner {
borrow_tracker_method: BorrowTrackerMethod,
/// Next unused pointer ID (tag).
next_ptr_tag: BorTag,
/// Table storing the "base" tag for each allocation.
/// The base tag is the one used for the initial pointer.
/// Table storing the "root" tag for each allocation.
/// The root tag is the one used for the initial pointer.
/// We need this in a separate table to handle cyclic statics.
base_ptr_tags: FxHashMap<AllocId, BorTag>,
root_ptr_tags: FxHashMap<AllocId, BorTag>,
/// Next unused call ID (for protectors).
next_call_id: CallId,
/// All currently protected tags.
@ -175,7 +175,7 @@ impl GlobalStateInner {
GlobalStateInner {
borrow_tracker_method,
next_ptr_tag: BorTag::one(),
base_ptr_tags: FxHashMap::default(),
root_ptr_tags: FxHashMap::default(),
next_call_id: NonZero::new(1).unwrap(),
protected_tags: FxHashMap::default(),
tracked_pointer_tags,
@ -213,8 +213,8 @@ impl GlobalStateInner {
}
}
pub fn base_ptr_tag(&mut self, id: AllocId, machine: &MiriMachine<'_, '_>) -> BorTag {
self.base_ptr_tags.get(&id).copied().unwrap_or_else(|| {
pub fn root_ptr_tag(&mut self, id: AllocId, machine: &MiriMachine<'_, '_>) -> BorTag {
self.root_ptr_tags.get(&id).copied().unwrap_or_else(|| {
let tag = self.new_ptr();
if self.tracked_pointer_tags.contains(&tag) {
machine.emit_diagnostic(NonHaltingDiagnostic::CreatedPointerTag(
@ -223,14 +223,14 @@ impl GlobalStateInner {
None,
));
}
trace!("New allocation {:?} has base tag {:?}", id, tag);
self.base_ptr_tags.try_insert(id, tag).unwrap();
trace!("New allocation {:?} has rpot tag {:?}", id, tag);
self.root_ptr_tags.try_insert(id, tag).unwrap();
tag
})
}
pub fn remove_unreachable_allocs(&mut self, allocs: &LiveAllocs<'_, '_, '_>) {
self.base_ptr_tags.retain(|id, _| allocs.is_live(*id));
self.root_ptr_tags.retain(|id, _| allocs.is_live(*id));
}
}

12
src/tools/miri/src/borrow_tracker/stacked_borrows/diagnostics.rs
View File

@ -20,7 +20,7 @@ fn err_sb_ub<'tcx>(
#[derive(Clone, Debug)]
pub struct AllocHistory {
id: AllocId,
base: (Item, Span),
root: (Item, Span),
creations: smallvec::SmallVec<[Creation; 1]>,
invalidations: smallvec::SmallVec<[Invalidation; 1]>,
protectors: smallvec::SmallVec<[Protection; 1]>,
@ -225,7 +225,7 @@ impl AllocHistory {
pub fn new(id: AllocId, item: Item, machine: &MiriMachine<'_, '_>) -> Self {
Self {
id,
base: (item, machine.current_span()),
root: (item, machine.current_span()),
creations: SmallVec::new(),
invalidations: SmallVec::new(),
protectors: SmallVec::new(),
@ -342,15 +342,15 @@ impl<'history, 'ecx, 'mir, 'tcx> DiagnosticCx<'history, 'ecx, 'mir, 'tcx> {
})
})
.or_else(|| {
// If we didn't find a retag that created this tag, it might be the base tag of
// If we didn't find a retag that created this tag, it might be the root tag of
// this allocation.
if self.history.base.0.tag() == tag {
if self.history.root.0.tag() == tag {
Some((
format!(
"{tag:?} was created here, as the base tag for {:?}",
"{tag:?} was created here, as the root tag for {:?}",
self.history.id
),
self.history.base.1.data(),
self.history.root.1.data(),
))
} else {
None

4
src/tools/miri/src/borrow_tracker/stacked_borrows/mod.rs
View File

@ -518,9 +518,9 @@ impl Stacks {
// not through a pointer). That is, whenever we directly write to a local, this will pop
// everything else off the stack, invalidating all previous pointers,
// and in particular, *all* raw pointers.
MemoryKind::Stack => (state.base_ptr_tag(id, machine), Permission::Unique),
MemoryKind::Stack => (state.root_ptr_tag(id, machine), Permission::Unique),
// Everything else is shared by default.
_ => (state.base_ptr_tag(id, machine), Permission::SharedReadWrite),
_ => (state.root_ptr_tag(id, machine), Permission::SharedReadWrite),
};
Stacks::new(size, perm, base_tag, id, machine)
}

10
src/tools/miri/src/borrow_tracker/stacked_borrows/stack.rs
View File

@ -47,7 +47,7 @@ impl Stack {
let mut first_removed = None;
// We never consider removing the bottom-most tag. For stacks without an unknown
// bottom this preserves the base tag.
// bottom this preserves the root tag.
// Note that the algorithm below is based on considering the tag at read_idx - 1,
// so precisely considering the tag at index 0 for removal when we have an unknown
// bottom would complicate the implementation. The simplification of not considering
@ -93,7 +93,7 @@ impl Stack {
self.unique_range = 0..self.len();
}
// Replace any Items which have been collected with the base item, a known-good value.
// Replace any Items which have been collected with the root item, a known-good value.
for i in 0..CACHE_LEN {
if self.cache.idx[i] >= first_removed {
self.cache.items[i] = self.borrows[0];
@ -331,7 +331,7 @@ impl<'tcx> Stack {
self.verify_cache_consistency();
}
/// Construct a new `Stack` using the passed `Item` as the base tag.
/// Construct a new `Stack` using the passed `Item` as the root tag.
pub fn new(item: Item) -> Self {
Stack {
borrows: vec![item],
@ -438,8 +438,8 @@ impl<'tcx> Stack {
let mut removed = 0;
let mut cursor = 0;
// Remove invalid entries from the cache by rotating them to the end of the cache, then
// keep track of how many invalid elements there are and overwrite them with the base tag.
// The base tag here serves as a harmless default value.
// keep track of how many invalid elements there are and overwrite them with the root tag.
// The root tag here serves as a harmless default value.
for _ in 0..CACHE_LEN - 1 {
if self.cache.idx[cursor] >= start {
self.cache.idx[cursor..CACHE_LEN - removed].rotate_left(1);

2
src/tools/miri/src/borrow_tracker/tree_borrows/mod.rs
View File

@ -37,7 +37,7 @@ impl<'tcx> Tree {
_kind: MemoryKind,
machine: &MiriMachine<'_, 'tcx>,
) -> Self {
let tag = state.base_ptr_tag(id, machine); // Fresh tag for the root
let tag = state.root_ptr_tag(id, machine); // Fresh tag for the root
let span = machine.current_span();
Tree::new(tag, size, span)
}

22
src/tools/miri/src/machine.rs
View File

@ -503,7 +503,7 @@ pub struct MiriMachine<'mir, 'tcx> {
/// Crates which are considered local for the purposes of error reporting.
pub(crate) local_crates: Vec<CrateNum>,
/// Mapping extern static names to their base pointer.
/// Mapping extern static names to their pointer.
extern_statics: FxHashMap<Symbol, Pointer<Provenance>>,
/// The random number generator used for resolving non-determinism.
@ -1042,14 +1042,14 @@ impl<'mir, 'tcx> Machine<'mir, 'tcx> for MiriMachine<'mir, 'tcx> {
ecx.generate_nan(inputs)
}
fn thread_local_static_base_pointer(
fn thread_local_static_pointer(
ecx: &mut MiriInterpCx<'mir, 'tcx>,
def_id: DefId,
) -> InterpResult<'tcx, Pointer<Provenance>> {
ecx.get_or_create_thread_local_alloc(def_id)
}
fn extern_static_base_pointer(
fn extern_static_pointer(
ecx: &MiriInterpCx<'mir, 'tcx>,
def_id: DefId,
) -> InterpResult<'tcx, Pointer<Provenance>> {
@ -1090,7 +1090,7 @@ impl<'mir, 'tcx> Machine<'mir, 'tcx> for MiriMachine<'mir, 'tcx> {
alloc: Cow<'b, Allocation>,
kind: Option<MemoryKind>,
) -> InterpResult<'tcx, Cow<'b, Allocation<Self::Provenance, Self::AllocExtra>>> {
let kind = kind.expect("we set our STATIC_KIND so this cannot be None");
let kind = kind.expect("we set our GLOBAL_KIND so this cannot be None");
if ecx.machine.tracked_alloc_ids.contains(&id) {
ecx.emit_diagnostic(NonHaltingDiagnostic::CreatedAlloc(
id,
@ -1135,7 +1135,7 @@ impl<'mir, 'tcx> Machine<'mir, 'tcx> for MiriMachine<'mir, 'tcx> {
weak_memory: buffer_alloc,
backtrace,
},
|ptr| ecx.global_base_pointer(ptr),
|ptr| ecx.global_root_pointer(ptr),
)?;
if matches!(kind, MemoryKind::Machine(kind) if kind.should_save_allocation_span()) {
@ -1148,31 +1148,33 @@ impl<'mir, 'tcx> Machine<'mir, 'tcx> for MiriMachine<'mir, 'tcx> {
Ok(Cow::Owned(alloc))
}
fn adjust_alloc_base_pointer(
fn adjust_alloc_root_pointer(
ecx: &MiriInterpCx<'mir, 'tcx>,
ptr: Pointer<CtfeProvenance>,
kind: Option<MemoryKind>,
) -> InterpResult<'tcx, Pointer<Provenance>> {
let kind = kind.expect("we set our GLOBAL_KIND so this cannot be None");
let alloc_id = ptr.provenance.alloc_id();
if cfg!(debug_assertions) {
// The machine promises to never call us on thread-local or extern statics.
match ecx.tcx.try_get_global_alloc(alloc_id) {
Some(GlobalAlloc::Static(def_id)) if ecx.tcx.is_thread_local_static(def_id) => {
panic!("adjust_alloc_base_pointer called on thread-local static")
panic!("adjust_alloc_root_pointer called on thread-local static")
}
Some(GlobalAlloc::Static(def_id)) if ecx.tcx.is_foreign_item(def_id) => {
panic!("adjust_alloc_base_pointer called on extern static")
panic!("adjust_alloc_root_pointer called on extern static")
}
_ => {}
}
}
// FIXME: can we somehow preserve the immutability of `ptr`?
let tag = if let Some(borrow_tracker) = &ecx.machine.borrow_tracker {
borrow_tracker.borrow_mut().base_ptr_tag(alloc_id, &ecx.machine)
borrow_tracker.borrow_mut().root_ptr_tag(alloc_id, &ecx.machine)
} else {
// Value does not matter, SB is disabled
BorTag::default()
};
ecx.ptr_from_rel_ptr(ptr, tag)
ecx.adjust_alloc_root_pointer(ptr, tag, kind)
}
/// Called on `usize as ptr` casts.

2
src/tools/miri/tests/fail/both_borrows/invalidate_against_protector3.stack.stderr
View File

@ -6,7 +6,7 @@ LL | unsafe { *x = 0 };
|
= help: this indicates a potential bug in the program: it performed an invalid operation, but the Stacked Borrows rules it violated are still experimental
= help: see https://github.com/rust-lang/unsafe-code-guidelines/blob/master/wip/stacked-borrows.md for further information
help: <TAG> was created here, as the base tag for ALLOC
help: <TAG> was created here, as the root tag for ALLOC
--> $DIR/invalidate_against_protector3.rs:LL:CC
|
LL | let ptr = alloc(Layout::for_value(&0i32)) as *mut i32;