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switch intptrcast to helper trait pattern like everything else
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@RalfJung
RalfJung committed Oct 15, 2023
1 parent 1cbb8fa commit 815a51c
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Showing 3 changed files with 80 additions and 95 deletions.
164 changes: 75 additions & 89 deletions src/intptrcast.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -62,10 +62,21 @@ impl GlobalStateInner {
}
}

impl<'mir, 'tcx> GlobalStateInner {
/// Shifts `addr` to make it aligned with `align` by rounding `addr` to the smallest multiple
/// of `align` that is larger or equal to `addr`
fn align_addr(addr: u64, align: u64) -> u64 {
match addr % align {
0 => addr,
rem => addr.checked_add(align).unwrap() - rem,
}
}

impl<'mir, 'tcx: 'mir> EvalContextExtPriv<'mir, 'tcx> for crate::MiriInterpCx<'mir, 'tcx> {}
trait EvalContextExtPriv<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
// Returns the exposed `AllocId` that corresponds to the specified addr,
// or `None` if the addr is out of bounds
fn alloc_id_from_addr(ecx: &MiriInterpCx<'mir, 'tcx>, addr: u64) -> Option<AllocId> {
fn alloc_id_from_addr(&self, addr: u64) -> Option<AllocId> {
let ecx = self.eval_context_ref();
let global_state = ecx.machine.intptrcast.borrow();
assert!(global_state.provenance_mode != ProvenanceMode::Strict);

Expand Down Expand Up @@ -105,70 +116,8 @@ impl<'mir, 'tcx> GlobalStateInner {
None
}

pub fn expose_ptr(
ecx: &mut MiriInterpCx<'mir, 'tcx>,
alloc_id: AllocId,
tag: BorTag,
) -> InterpResult<'tcx> {
let global_state = ecx.machine.intptrcast.get_mut();
// In strict mode, we don't need this, so we can save some cycles by not tracking it.
if global_state.provenance_mode != ProvenanceMode::Strict {
trace!("Exposing allocation id {alloc_id:?}");
global_state.exposed.insert(alloc_id);
if ecx.machine.borrow_tracker.is_some() {
ecx.expose_tag(alloc_id, tag)?;
}
}
Ok(())
}

pub fn ptr_from_addr_transmute(
_ecx: &MiriInterpCx<'mir, 'tcx>,
addr: u64,
) -> Pointer<Option<Provenance>> {
trace!("Transmuting {:#x} to a pointer", addr);

// We consider transmuted pointers to be "invalid" (`None` provenance).
Pointer::new(None, Size::from_bytes(addr))
}

pub fn ptr_from_addr_cast(
ecx: &MiriInterpCx<'mir, 'tcx>,
addr: u64,
) -> InterpResult<'tcx, Pointer<Option<Provenance>>> {
trace!("Casting {:#x} to a pointer", addr);

let global_state = ecx.machine.intptrcast.borrow();

match global_state.provenance_mode {
ProvenanceMode::Default => {
// The first time this happens at a particular location, print a warning.
thread_local! {
// `Span` is non-`Send`, so we use a thread-local instead.
static PAST_WARNINGS: RefCell<FxHashSet<Span>> = RefCell::default();
}
PAST_WARNINGS.with_borrow_mut(|past_warnings| {
let first = past_warnings.is_empty();
if past_warnings.insert(ecx.cur_span()) {
// Newly inserted, so first time we see this span.
ecx.emit_diagnostic(NonHaltingDiagnostic::Int2Ptr { details: first });
}
});
}
ProvenanceMode::Strict => {
throw_machine_stop!(TerminationInfo::Int2PtrWithStrictProvenance);
}
ProvenanceMode::Permissive => {}
}

// This is how wildcard pointers are born.
Ok(Pointer::new(Some(Provenance::Wildcard), Size::from_bytes(addr)))
}

fn alloc_base_addr(
ecx: &MiriInterpCx<'mir, 'tcx>,
alloc_id: AllocId,
) -> InterpResult<'tcx, u64> {
fn addr_from_alloc_id(&self, alloc_id: AllocId) -> InterpResult<'tcx, u64> {
let ecx = self.eval_context_ref();
let mut global_state = ecx.machine.intptrcast.borrow_mut();
let global_state = &mut *global_state;

Expand All @@ -191,7 +140,7 @@ impl<'mir, 'tcx> GlobalStateInner {
.next_base_addr
.checked_add(slack)
.ok_or_else(|| err_exhaust!(AddressSpaceFull))?;
let base_addr = Self::align_addr(base_addr, align.bytes());
let base_addr = align_addr(base_addr, align.bytes());
entry.insert(base_addr);
trace!(
"Assigning base address {:#x} to allocation {:?} (size: {}, align: {}, slack: {})",
Expand Down Expand Up @@ -221,14 +170,61 @@ impl<'mir, 'tcx> GlobalStateInner {
}
})
}
}

impl<'mir, 'tcx: 'mir> EvalContextExt<'mir, 'tcx> for crate::MiriInterpCx<'mir, 'tcx> {}
pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
fn expose_ptr(&mut self, alloc_id: AllocId, tag: BorTag) -> InterpResult<'tcx> {
let ecx = self.eval_context_mut();
let global_state = ecx.machine.intptrcast.get_mut();
// In strict mode, we don't need this, so we can save some cycles by not tracking it.
if global_state.provenance_mode != ProvenanceMode::Strict {
trace!("Exposing allocation id {alloc_id:?}");
global_state.exposed.insert(alloc_id);
if ecx.machine.borrow_tracker.is_some() {
ecx.expose_tag(alloc_id, tag)?;
}
}
Ok(())
}

fn ptr_from_addr_cast(&self, addr: u64) -> InterpResult<'tcx, Pointer<Option<Provenance>>> {
trace!("Casting {:#x} to a pointer", addr);

let ecx = self.eval_context_ref();
let global_state = ecx.machine.intptrcast.borrow();

match global_state.provenance_mode {
ProvenanceMode::Default => {
// The first time this happens at a particular location, print a warning.
thread_local! {
// `Span` is non-`Send`, so we use a thread-local instead.
static PAST_WARNINGS: RefCell<FxHashSet<Span>> = RefCell::default();
}
PAST_WARNINGS.with_borrow_mut(|past_warnings| {
let first = past_warnings.is_empty();
if past_warnings.insert(ecx.cur_span()) {
// Newly inserted, so first time we see this span.
ecx.emit_diagnostic(NonHaltingDiagnostic::Int2Ptr { details: first });
}
});
}
ProvenanceMode::Strict => {
throw_machine_stop!(TerminationInfo::Int2PtrWithStrictProvenance);
}
ProvenanceMode::Permissive => {}
}

// This is how wildcard pointers are born.
Ok(Pointer::new(Some(Provenance::Wildcard), Size::from_bytes(addr)))
}

/// Convert a relative (tcx) pointer to an absolute address.
pub fn rel_ptr_to_addr(
ecx: &MiriInterpCx<'mir, 'tcx>,
ptr: Pointer<AllocId>,
) -> InterpResult<'tcx, u64> {
fn rel_ptr_to_addr(&self, ptr: Pointer<AllocId>) -> InterpResult<'tcx, u64> {
let ecx = self.eval_context_ref();

let (alloc_id, offset) = ptr.into_parts(); // offset is relative (AllocId provenance)
let base_addr = GlobalStateInner::alloc_base_addr(ecx, alloc_id)?;
let base_addr = ecx.addr_from_alloc_id(alloc_id)?;

// Add offset with the right kind of pointer-overflowing arithmetic.
let dl = ecx.data_layout();
Expand All @@ -237,22 +233,21 @@ impl<'mir, 'tcx> GlobalStateInner {

/// When a pointer is used for a memory access, this computes where in which allocation the
/// access is going.
pub fn abs_ptr_to_rel(
ecx: &MiriInterpCx<'mir, 'tcx>,
ptr: Pointer<Provenance>,
) -> Option<(AllocId, Size)> {
fn abs_ptr_to_rel(&self, ptr: Pointer<Provenance>) -> Option<(AllocId, Size)> {
let ecx = self.eval_context_ref();

let (tag, addr) = ptr.into_parts(); // addr is absolute (Tag provenance)

let alloc_id = if let Provenance::Concrete { alloc_id, .. } = tag {
alloc_id
} else {
// A wildcard pointer.
GlobalStateInner::alloc_id_from_addr(ecx, addr.bytes())?
ecx.alloc_id_from_addr(addr.bytes())?
};

// This cannot fail: since we already have a pointer with that provenance, rel_ptr_to_addr
// must have been called in the past.
let base_addr = GlobalStateInner::alloc_base_addr(ecx, alloc_id).unwrap();
let base_addr = ecx.addr_from_alloc_id(alloc_id).unwrap();

// Wrapping "addr - base_addr"
let dl = ecx.data_layout();
Expand All @@ -263,15 +258,6 @@ impl<'mir, 'tcx> GlobalStateInner {
Size::from_bytes(dl.overflowing_signed_offset(addr.bytes(), neg_base_addr).0),
))
}

/// Shifts `addr` to make it aligned with `align` by rounding `addr` to the smallest multiple
/// of `align` that is larger or equal to `addr`
fn align_addr(addr: u64, align: u64) -> u64 {
match addr % align {
0 => addr,
rem => addr.checked_add(align).unwrap() - rem,
}
}
}

#[cfg(test)]
Expand All @@ -280,7 +266,7 @@ mod tests {

#[test]
fn test_align_addr() {
assert_eq!(GlobalStateInner::align_addr(37, 4), 40);
assert_eq!(GlobalStateInner::align_addr(44, 4), 44);
assert_eq!(align_addr(37, 4), 40);
assert_eq!(align_addr(44, 4), 44);
}
}
2 changes: 1 addition & 1 deletion src/lib.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -117,7 +117,7 @@ pub use crate::eval::{
create_ecx, eval_entry, AlignmentCheck, BacktraceStyle, IsolatedOp, MiriConfig, RejectOpWith,
};
pub use crate::helpers::EvalContextExt as _;
pub use crate::intptrcast::ProvenanceMode;
pub use crate::intptrcast::{EvalContextExt as _, ProvenanceMode};
pub use crate::machine::{
AllocExtra, FrameExtra, MiriInterpCx, MiriInterpCxExt, MiriMachine, MiriMemoryKind,
PrimitiveLayouts, Provenance, ProvenanceExtra,
Expand Down
9 changes: 4 additions & 5 deletions src/machine.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1125,7 +1125,7 @@ impl<'mir, 'tcx> Machine<'mir, 'tcx> for MiriMachine<'mir, 'tcx> {
_ => {}
}
}
let absolute_addr = intptrcast::GlobalStateInner::rel_ptr_to_addr(ecx, ptr)?;
let absolute_addr = ecx.rel_ptr_to_addr(ptr)?;
let tag = if let Some(borrow_tracker) = &ecx.machine.borrow_tracker {
borrow_tracker.borrow_mut().base_ptr_tag(ptr.provenance, &ecx.machine)
} else {
Expand All @@ -1143,16 +1143,15 @@ impl<'mir, 'tcx> Machine<'mir, 'tcx> for MiriMachine<'mir, 'tcx> {
ecx: &MiriInterpCx<'mir, 'tcx>,
addr: u64,
) -> InterpResult<'tcx, Pointer<Option<Self::Provenance>>> {
intptrcast::GlobalStateInner::ptr_from_addr_cast(ecx, addr)
ecx.ptr_from_addr_cast(addr)
}

fn expose_ptr(
ecx: &mut InterpCx<'mir, 'tcx, Self>,
ptr: Pointer<Self::Provenance>,
) -> InterpResult<'tcx> {
match ptr.provenance {
Provenance::Concrete { alloc_id, tag } =>
intptrcast::GlobalStateInner::expose_ptr(ecx, alloc_id, tag),
Provenance::Concrete { alloc_id, tag } => ecx.expose_ptr(alloc_id, tag),
Provenance::Wildcard => {
// No need to do anything for wildcard pointers as
// their provenances have already been previously exposed.
Expand All @@ -1167,7 +1166,7 @@ impl<'mir, 'tcx> Machine<'mir, 'tcx> for MiriMachine<'mir, 'tcx> {
ecx: &MiriInterpCx<'mir, 'tcx>,
ptr: Pointer<Self::Provenance>,
) -> Option<(AllocId, Size, Self::ProvenanceExtra)> {
let rel = intptrcast::GlobalStateInner::abs_ptr_to_rel(ecx, ptr);
let rel = ecx.abs_ptr_to_rel(ptr);

rel.map(|(alloc_id, size)| {
let tag = match ptr.provenance {
Expand Down

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