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Fix pop_stack_frame logic

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This commit is contained in:
Jonas Schievink
2020-04-16 01:32:05 +02:00
parent a417f963fe
commit 34ed891895
1 changed files with 7 additions and 22 deletions
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src/librustc_mir/interpret/eval_context.rs
+7 -22
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@@ -724,10 +724,14 @@ pub(super) fn pop_stack_frame(&mut self, unwinding: bool) -> InterpResult<'tcx>
let frame =
self.stack_mut().pop().expect("tried to pop a stack frame, but there were none");
if let Some(return_place) = frame.return_place {
if !unwinding {
// Copy the return value to the caller's stack frame.
let op = self.access_local(&frame, mir::RETURN_PLACE, None)?;
self.copy_op(op, return_place)?;
if let Some(return_place) = frame.return_place {
let op = self.access_local(&frame, mir::RETURN_PLACE, None)?;
self.copy_op(op, return_place)?;
} else {
throw_ub!(Unreachable);
}
}
// Now where do we jump next?
@@ -768,25 +772,6 @@ pub(super) fn pop_stack_frame(&mut self, unwinding: bool) -> InterpResult<'tcx>
self.unwind_to_block(unwind);
} else {
// Follow the normal return edge.
// Validate the return value. Do this after deallocating so that we catch dangling
// references.
if let Some(return_place) = return_place {
if M::enforce_validity(self) {
// Data got changed, better make sure it matches the type!
// It is still possible that the return place held invalid data while
// the function is running, but that's okay because nobody could have
// accessed that same data from the "outside" to observe any broken
// invariant -- that is, unless a function somehow has a ptr to
// its return place... but the way MIR is currently generated, the
// return place is always a local and then this cannot happen.
self.validate_operand(self.place_to_op(return_place)?)?;
}
} else {
// Uh, that shouldn't happen... the function did not intend to return
throw_ub!(Unreachable);
}
// Jump to new block -- *after* validation so that the spans make more sense.
if let Some(ret) = next_block {
self.return_to_block(ret)?;
}