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Rollup merge of #95221 - RalfJung:check_and_deref_ptr, r=oli-obk

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interpret/memory: simplify check_and_deref_ptr

*Finally* I saw a way to make this code simpler. The odd preprocessing in `let ptr_or_addr =` has bothered me since forever, but it actually became unnecessary in the last provenance refactoring. :)

This also leads to slightly more explicit error messages as a nice side-effect. 🎉

r? `@oli-obk`
This commit is contained in:
Matthias Krüger 2022-03-23 22:13:24 +01:00 • committed by GitHub
commit 23ef234bf7
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8 changed files with 14 additions and 24 deletions
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20
compiler/rustc_const_eval/src/interpret/memory.rs
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@ -427,22 +427,12 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
}
}
// Extract from the pointer an `Option<AllocId>` and an offset, which is relative to the
// allocation or (if that is `None`) an absolute address.
let ptr_or_addr = if size.bytes() == 0 {
// Let's see what we can do, but don't throw errors if there's nothing there.
self.ptr_try_get_alloc(ptr)
} else {
// A "real" access, we insist on getting an `AllocId`.
Ok(self.ptr_get_alloc(ptr)?)
};
Ok(match ptr_or_addr {
Ok(match self.ptr_try_get_alloc(ptr) {
Err(addr) => {
// No memory is actually being accessed.
debug_assert!(size.bytes() == 0);
// Must be non-null.
if addr == 0 {
throw_ub!(DanglingIntPointer(0, msg))
// We couldn't get a proper allocation. This is only okay if the access size is 0,
// and the address is not null.
if size.bytes() > 0 || addr == 0 {
throw_ub!(DanglingIntPointer(addr, msg));
}
// Must be aligned.
if let Some(align) = align {