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borrow tracking: simplify provenance updating

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This commit is contained in:
Ralf Jung 2023-08-04 14:33:09 +02:00
parent a73c86d8a5
commit e55f49415d
2 changed files with 20 additions and 55 deletions
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37
src/tools/miri/src/borrow_tracker/stacked_borrows/mod.rs
View File

@ -604,8 +604,7 @@ impl<'mir: 'ecx, 'tcx: 'mir, 'ecx> EvalContextPrivExt<'mir, 'tcx, 'ecx>
{
}
trait EvalContextPrivExt<'mir: 'ecx, 'tcx: 'mir, 'ecx>: crate::MiriInterpCxExt<'mir, 'tcx> {
/// Returns the `AllocId` the reborrow was done in, if some actual borrow stack manipulation
/// happened.
/// Returns the provenance that should be used henceforth.
fn sb_reborrow(
&mut self,
place: &MPlaceTy<'tcx, Provenance>,
@ -613,7 +612,7 @@ trait EvalContextPrivExt<'mir: 'ecx, 'tcx: 'mir, 'ecx>: crate::MiriInterpCxExt<'
new_perm: NewPermission,
new_tag: BorTag,
retag_info: RetagInfo, // diagnostics info about this retag
) -> InterpResult<'tcx, Option<AllocId>> {
) -> InterpResult<'tcx, Option<Provenance>> {
let this = self.eval_context_mut();
// Ensure we bail out if the pointer goes out-of-bounds (see miri#1050).
this.check_ptr_access_align(place.ptr, size, Align::ONE, CheckInAllocMsg::InboundsTest)?;
@ -695,11 +694,14 @@ trait EvalContextPrivExt<'mir: 'ecx, 'tcx: 'mir, 'ecx>: crate::MiriInterpCxExt<'
// pointer tagging for example all calls to get_unchecked on them are invalid.
if let Ok((alloc_id, base_offset, orig_tag)) = this.ptr_try_get_alloc_id(place.ptr) {
log_creation(this, Some((alloc_id, base_offset, orig_tag)))?;
return Ok(Some(alloc_id));
// Still give it the new provenance, it got retagged after all.
return Ok(Some(Provenance::Concrete { alloc_id, tag: new_tag }));
} else {
// This pointer doesn't come with an AllocId. :shrug:
log_creation(this, None)?;
// Provenance unchanged.
return Ok(place.ptr.provenance);
}
// This pointer doesn't come with an AllocId. :shrug:
log_creation(this, None)?;
return Ok(None);
}
let (alloc_id, base_offset, orig_tag) = this.ptr_get_alloc_id(place.ptr)?;
@ -804,7 +806,7 @@ trait EvalContextPrivExt<'mir: 'ecx, 'tcx: 'mir, 'ecx>: crate::MiriInterpCxExt<'
}
}
Ok(Some(alloc_id))
Ok(Some(Provenance::Concrete { alloc_id, tag: new_tag }))
}
/// Retags an individual pointer, returning the retagged version.
@ -831,25 +833,10 @@ trait EvalContextPrivExt<'mir: 'ecx, 'tcx: 'mir, 'ecx>: crate::MiriInterpCxExt<'
let new_tag = this.machine.borrow_tracker.as_mut().unwrap().get_mut().new_ptr();
// Reborrow.
let alloc_id = this.sb_reborrow(&place, size, new_perm, new_tag, info)?;
let new_prov = this.sb_reborrow(&place, size, new_perm, new_tag, info)?;
// Adjust pointer.
let new_place = place.map_provenance(|p| {
p.map(|prov| {
match alloc_id {
Some(alloc_id) => {
// If `reborrow` could figure out the AllocId of this ptr, hard-code it into the new one.
// Even if we started out with a wildcard, this newly retagged pointer is tied to that allocation.
Provenance::Concrete { alloc_id, tag: new_tag }
}
None => {
// Looks like this has to stay a wildcard pointer.
assert!(matches!(prov, Provenance::Wildcard));
Provenance::Wildcard
}
}
})
});
let new_place = place.map_provenance(|_| new_prov);
// Return new pointer.
Ok(ImmTy::from_immediate(new_place.to_ref(this), val.layout))

38
src/tools/miri/src/borrow_tracker/tree_borrows/mod.rs
View File

@ -161,22 +161,14 @@ impl<'mir: 'ecx, 'tcx: 'mir, 'ecx> EvalContextPrivExt<'mir, 'tcx, 'ecx>
{
}
trait EvalContextPrivExt<'mir: 'ecx, 'tcx: 'mir, 'ecx>: crate::MiriInterpCxExt<'mir, 'tcx> {
/// Returns the `AllocId` the reborrow was done in, if there is some actual
/// memory associated with this pointer. Returns `None` if there is no actual
/// memory allocated. Also checks that the reborrow of size `ptr_size` is
/// within bounds of the allocation.
///
/// Also returns the tag that the pointer should get, which is essentially
/// `if new_perm.is_some() { new_tag } else { parent_tag }` along with
/// some logging (always) and fake reads (if `new_perm` is
/// `Some(NewPermission { perform_read_access: true }`).
/// Returns the provenance that should be used henceforth.
fn tb_reborrow(
&mut self,
place: &MPlaceTy<'tcx, Provenance>, // parent tag extracted from here
ptr_size: Size,
new_perm: NewPermission,
new_tag: BorTag,
) -> InterpResult<'tcx, Option<(AllocId, BorTag)>> {
) -> InterpResult<'tcx, Option<Provenance>> {
let this = self.eval_context_mut();
// Ensure we bail out if the pointer goes out-of-bounds (see miri#1050).
this.check_ptr_access_align(
@ -222,13 +214,14 @@ trait EvalContextPrivExt<'mir: 'ecx, 'tcx: 'mir, 'ecx>: crate::MiriInterpCxExt<'
place.layout.ty,
);
log_creation(this, None)?;
return Ok(None);
// Keep original provenance.
return Ok(place.ptr.provenance);
}
};
log_creation(this, Some((alloc_id, base_offset, parent_prov)))?;
let orig_tag = match parent_prov {
ProvenanceExtra::Wildcard => return Ok(None), // TODO: handle wildcard pointers
ProvenanceExtra::Wildcard => return Ok(place.ptr.provenance), // TODO: handle wildcard pointers
ProvenanceExtra::Concrete(tag) => tag,
};
@ -279,7 +272,7 @@ trait EvalContextPrivExt<'mir: 'ecx, 'tcx: 'mir, 'ecx>: crate::MiriInterpCxExt<'
// Record the parent-child pair in the tree.
tree_borrows.new_child(orig_tag, new_tag, new_perm.initial_state, range, span)?;
Ok(Some((alloc_id, new_tag)))
Ok(Some(Provenance::Concrete { alloc_id, tag: new_tag }))
}
/// Retags an individual pointer, returning the retagged version.
@ -315,25 +308,10 @@ trait EvalContextPrivExt<'mir: 'ecx, 'tcx: 'mir, 'ecx>: crate::MiriInterpCxExt<'
let new_tag = this.machine.borrow_tracker.as_mut().unwrap().get_mut().new_ptr();
// Compute the actual reborrow.
let reborrowed = this.tb_reborrow(&place, reborrow_size, new_perm, new_tag)?;
let new_prov = this.tb_reborrow(&place, reborrow_size, new_perm, new_tag)?;
// Adjust pointer.
let new_place = place.map_provenance(|p| {
p.map(|prov| {
match reborrowed {
Some((alloc_id, actual_tag)) => {
// If `reborrow` could figure out the AllocId of this ptr, hard-code it into the new one.
// Even if we started out with a wildcard, this newly retagged pointer is tied to that allocation.
Provenance::Concrete { alloc_id, tag: actual_tag }
}
None => {
// Looks like this has to stay a wildcard pointer.
assert!(matches!(prov, Provenance::Wildcard));
Provenance::Wildcard
}
}
})
});
let new_place = place.map_provenance(|_| new_prov);
// Return new pointer.
Ok(ImmTy::from_immediate(new_place.to_ref(this), val.layout))