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get rid of Rc in Stacked Borrows

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This commit is contained in:
Ralf Jung 2021-05-22 13:24:08 +02:00
parent 3a24958128
commit ca7283d746
2 changed files with 29 additions and 30 deletions
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18
src/machine.rs
View file

@ -116,7 +116,7 @@ pub struct AllocExtra {
}
/// Extra global memory data
#[derive(Clone, Debug)]
#[derive(Debug)]
pub struct MemoryExtra {
pub stacked_borrows: Option<stacked_borrows::MemoryExtra>,
pub data_race: Option<data_race::MemoryExtra>,
@ -144,11 +144,11 @@ impl MemoryExtra {
pub fn new(config: &MiriConfig) -> Self {
let rng = StdRng::seed_from_u64(config.seed.unwrap_or(0));
let stacked_borrows = if config.stacked_borrows {
Some(Rc::new(RefCell::new(stacked_borrows::GlobalState::new(
Some(RefCell::new(stacked_borrows::GlobalState::new(
config.tracked_pointer_tag,
config.tracked_call_id,
config.track_raw,
))))
)))
} else {
None
};
@ -478,7 +478,7 @@ impl<'mir, 'tcx> Machine<'mir, 'tcx> for Evaluator<'mir, 'tcx> {
let alloc = alloc.into_owned();
let (stacks, base_tag) = if let Some(stacked_borrows) = &memory_extra.stacked_borrows {
let (stacks, base_tag) =
Stacks::new_allocation(id, alloc.size(), Rc::clone(stacked_borrows), kind);
Stacks::new_allocation(id, alloc.size(), stacked_borrows, kind);
(Some(stacks), base_tag)
} else {
// No stacks, no tag.
@ -507,7 +507,7 @@ impl<'mir, 'tcx> Machine<'mir, 'tcx> for Evaluator<'mir, 'tcx> {
#[inline(always)]
fn memory_read(
_memory_extra: &Self::MemoryExtra,
memory_extra: &Self::MemoryExtra,
alloc_extra: &AllocExtra,
ptr: Pointer<Tag>,
size: Size,
@ -516,7 +516,7 @@ impl<'mir, 'tcx> Machine<'mir, 'tcx> for Evaluator<'mir, 'tcx> {
data_race.read(ptr, size)?;
}
if let Some(stacked_borrows) = &alloc_extra.stacked_borrows {
stacked_borrows.memory_read(ptr, size)
stacked_borrows.memory_read(ptr, size, memory_extra.stacked_borrows.as_ref().unwrap())
} else {
Ok(())
}
@ -524,7 +524,7 @@ impl<'mir, 'tcx> Machine<'mir, 'tcx> for Evaluator<'mir, 'tcx> {
#[inline(always)]
fn memory_written(
_memory_extra: &mut Self::MemoryExtra,
memory_extra: &mut Self::MemoryExtra,
alloc_extra: &mut AllocExtra,
ptr: Pointer<Tag>,
size: Size,
@ -533,7 +533,7 @@ impl<'mir, 'tcx> Machine<'mir, 'tcx> for Evaluator<'mir, 'tcx> {
data_race.write(ptr, size)?;
}
if let Some(stacked_borrows) = &mut alloc_extra.stacked_borrows {
stacked_borrows.memory_written(ptr, size)
stacked_borrows.memory_written(ptr, size, memory_extra.stacked_borrows.as_mut().unwrap())
} else {
Ok(())
}
@ -553,7 +553,7 @@ impl<'mir, 'tcx> Machine<'mir, 'tcx> for Evaluator<'mir, 'tcx> {
data_race.deallocate(ptr, size)?;
}
if let Some(stacked_borrows) = &mut alloc_extra.stacked_borrows {
stacked_borrows.memory_deallocated(ptr, size)
stacked_borrows.memory_deallocated(ptr, size, memory_extra.stacked_borrows.as_mut().unwrap())
} else {
Ok(())
}

41
src/stacked_borrows.rs
View file

@ -4,8 +4,6 @@
use std::cell::RefCell;
use std::fmt;
use std::num::NonZeroU64;
use std::rc::Rc;
use log::trace;
use rustc_data_structures::fx::{FxHashMap, FxHashSet};
@ -87,8 +85,6 @@ pub struct Stack {
pub struct Stacks {
// Even reading memory can have effects on the stack, so we need a `RefCell` here.
stacks: RefCell<RangeMap<Stack>>,
// Pointer to global state
global: MemoryExtra,
}
/// Extra global state, available to the memory access hooks.
@ -112,7 +108,7 @@ pub struct GlobalState {
track_raw: bool,
}
/// Memory extra state gives us interior mutable access to the global state.
pub type MemoryExtra = Rc<RefCell<GlobalState>>;
pub type MemoryExtra = RefCell<GlobalState>;
/// Indicates which kind of access is being performed.
#[derive(Copy, Clone, Hash, PartialEq, Eq)]
@ -449,11 +445,11 @@ impl<'tcx> Stack {
/// Map per-stack operations to higher-level per-location-range operations.
impl<'tcx> Stacks {
/// Creates new stack with initial tag.
fn new(size: Size, perm: Permission, tag: Tag, extra: MemoryExtra) -> Self {
fn new(size: Size, perm: Permission, tag: Tag) -> Self {
let item = Item { perm, tag, protector: None };
let stack = Stack { borrows: vec![item] };
Stacks { stacks: RefCell::new(RangeMap::new(size, stack)), global: extra }
Stacks { stacks: RefCell::new(RangeMap::new(size, stack)) }
}
/// Call `f` on every stack in the range.
@ -461,9 +457,9 @@ impl<'tcx> Stacks {
&self,
ptr: Pointer<Tag>,
size: Size,
global: &GlobalState,
f: impl Fn(Pointer<Tag>, &mut Stack, &GlobalState) -> InterpResult<'tcx>,
) -> InterpResult<'tcx> {
let global = self.global.borrow();
let mut stacks = self.stacks.borrow_mut();
for (offset, stack) in stacks.iter_mut(ptr.offset, size) {
let mut cur_ptr = ptr;
@ -479,16 +475,17 @@ impl Stacks {
pub fn new_allocation(
id: AllocId,
size: Size,
extra: MemoryExtra,
extra: &MemoryExtra,
kind: MemoryKind<MiriMemoryKind>,
) -> (Self, Tag) {
let mut extra = extra.borrow_mut();
let (tag, perm) = match kind {
// New unique borrow. This tag is not accessible by the program,
// so it will only ever be used when using the local directly (i.e.,
// 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 => (Tag::Tagged(extra.borrow_mut().new_ptr()), Permission::Unique),
MemoryKind::Stack => (Tag::Tagged(extra.new_ptr()), Permission::Unique),
// `Global` memory can be referenced by global pointers from `tcx`.
// Thus we call `global_base_ptr` such that the global pointers get the same tag
// as what we use here.
@ -500,28 +497,27 @@ impl Stacks {
| MiriMemoryKind::ExternStatic
| MiriMemoryKind::Tls
| MiriMemoryKind::Env,
) => (extra.borrow_mut().global_base_ptr(id), Permission::SharedReadWrite),
) => (extra.global_base_ptr(id), Permission::SharedReadWrite),
// Everything else we handle like raw pointers for now.
_ => {
let mut extra = extra.borrow_mut();
let tag =
if extra.track_raw { Tag::Tagged(extra.new_ptr()) } else { Tag::Untagged };
(tag, Permission::SharedReadWrite)
}
};
(Stacks::new(size, perm, tag, extra), tag)
(Stacks::new(size, perm, tag), tag)
}
#[inline(always)]
pub fn memory_read<'tcx>(&self, ptr: Pointer<Tag>, size: Size) -> InterpResult<'tcx> {
pub fn memory_read<'tcx>(&self, ptr: Pointer<Tag>, size: Size, extra: &MemoryExtra) -> InterpResult<'tcx> {
trace!("read access with tag {:?}: {:?}, size {}", ptr.tag, ptr.erase_tag(), size.bytes());
self.for_each(ptr, size, |ptr, stack, global| stack.access(AccessKind::Read, ptr, global))
self.for_each(ptr, size, &*extra.borrow(), |ptr, stack, global| stack.access(AccessKind::Read, ptr, global))
}
#[inline(always)]
pub fn memory_written<'tcx>(&mut self, ptr: Pointer<Tag>, size: Size) -> InterpResult<'tcx> {
pub fn memory_written<'tcx>(&mut self, ptr: Pointer<Tag>, size: Size, extra: &mut MemoryExtra) -> InterpResult<'tcx> {
trace!("write access with tag {:?}: {:?}, size {}", ptr.tag, ptr.erase_tag(), size.bytes());
self.for_each(ptr, size, |ptr, stack, global| stack.access(AccessKind::Write, ptr, global))
self.for_each(ptr, size, extra.get_mut(), |ptr, stack, global| stack.access(AccessKind::Write, ptr, global))
}
#[inline(always)]
@ -529,9 +525,10 @@ impl Stacks {
&mut self,
ptr: Pointer<Tag>,
size: Size,
extra: &mut MemoryExtra,
) -> InterpResult<'tcx> {
trace!("deallocation with tag {:?}: {:?}, size {}", ptr.tag, ptr.erase_tag(), size.bytes());
self.for_each(ptr, size, |ptr, stack, global| stack.dealloc(ptr, global))
self.for_each(ptr, size, extra.get_mut(), |ptr, stack, global| stack.dealloc(ptr, global))
}
}
@ -560,10 +557,12 @@ trait EvalContextPrivExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
size.bytes()
);
// Get the allocation. It might not be mutable, so we cannot use `get_mut`.
// Get the allocation. We need both the allocation and the MemoryExtra, so we cannot use `&mut`.
// FIXME: make `get_alloc_extra_mut` also return `&mut MemoryExtra`.
let extra = this.memory.get_alloc_extra(ptr.alloc_id)?;
let stacked_borrows =
extra.stacked_borrows.as_ref().expect("we should have Stacked Borrows data");
let global = this.memory.extra.stacked_borrows.as_ref().unwrap().borrow();
// Update the stacks.
// Make sure that raw pointers and mutable shared references are reborrowed "weak":
// There could be existing unique pointers reborrowed from them that should remain valid!
@ -583,14 +582,14 @@ trait EvalContextPrivExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
Permission::SharedReadWrite
};
let item = Item { perm, tag: new_tag, protector };
stacked_borrows.for_each(cur_ptr, size, |cur_ptr, stack, global| {
stacked_borrows.for_each(cur_ptr, size, &*global, |cur_ptr, stack, global| {
stack.grant(cur_ptr, item, global)
})
});
}
};
let item = Item { perm, tag: new_tag, protector };
stacked_borrows.for_each(ptr, size, |ptr, stack, global| stack.grant(ptr, item, global))
stacked_borrows.for_each(ptr, size, &*global, |ptr, stack, global| stack.grant(ptr, item, global))
}
/// Retags an indidual pointer, returning the retagged version.