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consolidate making Undef release a NOP in one place

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This commit is contained in:
Ralf Jung 2017-08-04 16:01:46 -07:00
parent 4957031e3c
commit fb2ed457c6
2 changed files with 10 additions and 9 deletions
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17
src/librustc_mir/interpret/validation.rs
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@ -11,7 +11,7 @@ use super::{
EvalError, EvalResult, EvalErrorKind,
EvalContext, DynamicLifetime,
AccessKind, LockInfo,
PrimVal, Value,
Value,
Lvalue, LvalueExtra,
Machine,
};
@ -156,10 +156,11 @@ impl<'a, 'tcx, M: Machine<'tcx>> EvalContext<'a, 'tcx, M> {
fn validate(&mut self, query: ValidationQuery<'tcx>, mode: ValidationMode) -> EvalResult<'tcx>
{
match self.try_validate(query, mode) {
// HACK: If, during releasing, we hit memory we cannot use, we just ignore that.
// This can happen because releases are added before drop elaboration.
// TODO: Fix the MIR so that these releases do not happen.
res @ Err(EvalError{ kind: EvalErrorKind::DanglingPointerDeref, ..}) |
// Releasing an uninitalized variable is a NOP. This is needed because
// we have to release the return value of a function; due to destination-passing-style
// the callee may directly write there.
// TODO: Ideally we would know whether the destination is already initialized, and only
// release if it is.
res @ Err(EvalError{ kind: EvalErrorKind::ReadUndefBytes, ..}) => {
if let ValidationMode::Release = mode {
return Ok(());
@ -187,16 +188,14 @@ impl<'a, 'tcx, M: Machine<'tcx>> EvalContext<'a, 'tcx, M> {
}
}
// Release of an Undef local is fine, and a NOP.
// HACK: For now, bail out if we hit a dead local during recovery (can happen because sometimes we have
// StorageDead before EndRegion).
// StorageDead before EndRegion due to https://github.com/rust-lang/rust/issues/43481).
// TODO: We should rather fix the MIR.
match query.lval {
Lvalue::Local { frame, local } => {
let res = self.stack[frame].get_local(local);
match (res, mode) {
(Err(EvalError{ kind: EvalErrorKind::DeadLocal, ..}), ValidationMode::Recover(_)) |
(Ok(Value::ByVal(PrimVal::Undef)), ValidationMode::Release) => {
(Err(EvalError{ kind: EvalErrorKind::DeadLocal, ..}), ValidationMode::Recover(_)) => {
return Ok(());
}
_ => {},

2
src/librustc_mir/interpret/value.rs
View file

@ -197,6 +197,7 @@ impl<'a, 'tcx: 'a> Value {
ByValPair(ptr, vtable) => Ok((ptr.into(), vtable.to_ptr()?)),
ByVal(PrimVal::Undef) => err!(ReadUndefBytes),
_ => bug!("expected ptr and vtable, got {:?}", self),
}
}
@ -216,6 +217,7 @@ impl<'a, 'tcx: 'a> Value {
assert_eq!(len as u64 as u128, len);
Ok((ptr.into(), len as u64))
},
ByVal(PrimVal::Undef) => err!(ReadUndefBytes),
ByVal(_) => bug!("expected ptr and length, got {:?}", self),
}
}