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Rewrite get_size_and_align so it doesn't duplicate work

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This commit is contained in:
Oliver Scherer 2019-07-25 23:53:05 +02:00
parent b75dfa8a2b
commit d9ac0c67ed
1 changed files with 35 additions and 34 deletions
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69
src/librustc_mir/interpret/memory.rs
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@ -535,40 +535,41 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
id: AllocId,
liveness: AllocCheck,
) -> InterpResult<'static, (Size, Align)> {
// Allocations of `static` items
// Can't do this in the match argument, we may get cycle errors since the lock would
// be held throughout the match.
let alloc = self.tcx.alloc_map.lock().get(id);
match alloc {
Some(GlobalAlloc::Static(did)) => {
// Use size and align of the type
let ty = self.tcx.type_of(did);
let layout = self.tcx.layout_of(ParamEnv::empty().and(ty)).unwrap();
return Ok((layout.size, layout.align.abi));
}
_ => {}
}
// Regular allocations.
if let Ok(alloc) = self.get(id) {
return Ok((Size::from_bytes(alloc.bytes.len() as u64), alloc.align));
}
// Function pointers.
if let Ok(_) = self.get_fn_alloc(id) {
return if let AllocCheck::Dereferencable = liveness {
// The caller requested no function pointers.
err!(DerefFunctionPointer)
} else {
Ok((Size::ZERO, Align::from_bytes(1).unwrap()))
};
}
// The rest must be dead.
if let AllocCheck::MaybeDead = liveness {
// Deallocated pointers are allowed, we should be able to find
// them in the map.
Ok(*self.dead_alloc_map.get(&id)
.expect("deallocated pointers should all be recorded in `dead_alloc_map`"))
} else {
err!(DanglingPointerDeref)
let alloc_or_size_align = self.alloc_map.get_or(id, || -> Result<_, InterpResult<'static, (Size, Align)>> {
// Can't do this in the match argument, we may get cycle errors since the lock would
// be held throughout the match.
let alloc = self.tcx.alloc_map.lock().get(id);
Err(match alloc {
Some(GlobalAlloc::Static(did)) => {
// Use size and align of the type
let ty = self.tcx.type_of(did);
let layout = self.tcx.layout_of(ParamEnv::empty().and(ty)).unwrap();
Ok((layout.size, layout.align.abi))
},
Some(GlobalAlloc::Memory(alloc)) =>
// this duplicates the logic on the `match alloc_or_size_align`, but due to the
// API of `get_or` there's no way around that.
Ok((Size::from_bytes(alloc.bytes.len() as u64), alloc.align)),
Some(GlobalAlloc::Function(_)) => if let AllocCheck::Dereferencable = liveness {
// The caller requested no function pointers.
err!(DerefFunctionPointer)
} else {
Ok((Size::ZERO, Align::from_bytes(1).unwrap()))
},
// The rest must be dead.
None => if let AllocCheck::MaybeDead = liveness {
// Deallocated pointers are allowed, we should be able to find
// them in the map.
Ok(*self.dead_alloc_map.get(&id)
.expect("deallocated pointers should all be recorded in `dead_alloc_map`"))
} else {
err!(DanglingPointerDeref)
},
})
});
match alloc_or_size_align {
Ok((_, alloc)) => Ok((Size::from_bytes(alloc.bytes.len() as u64), alloc.align)),
Err(done) => done,
}
}