Auto merge of #62081 - RalfJung:miri-pointer-checks, r=oli-obk

Refactor miri pointer checks

Centralize bounds, alignment and NULL checking for memory accesses in one function: `memory.check_ptr_access`. That function also takes care of converting a `Scalar` to a `Pointer`, should that be needed.  Not all accesses need that though: if the access has size 0, `None` is returned. Everyone accessing memory based on a `Scalar` should use this method to get the `Pointer` they need.

All operations on the `Allocation` work on `Pointer` inputs and expect all the checks to have happened (and will ICE if the bounds are violated). The operations on `Memory` work on `Scalar` inputs and do the checks themselves.

The only other public method to check pointers is `memory.ptr_may_be_null`, which is needed in a few places. No need for `check_align` or similar methods. That makes the public API surface much easier to use and harder to mis-use.

This should be largely no-functional-change, except that ZST accesses to a "true" pointer that is dangling or out-of-bounds are now considered UB. This is to be conservative wrt. whatever LLVM might be doing.

While I am at it, this also removes the assumption that the vtable part of a `dyn Trait`-fat-pointer is a `Pointer` (as opposed to a pointer cast to an integer, stored as raw bits).

r? @oli-obk

0 files changed, 0 insertions, 0 deletions