stdarch Add TBI helpers for AArch64

Adds a trait to core_arch for AArch64 to set a value in the top byte of a pointer (which should logically become the canonical address of the allocation), and to retrieve the value stored in the top byte of a pointer, if any.

The intent is for a Rust-provided mechanism for such adjustments to pointers, so that any internal pointer tracking could be updated as necessary, such as to enable this pattern within Miri.

Aug 02 '24 15:08 dheaton-arm

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @Amanieu (or someone else) some time within the next two weeks.

Aug 02 '24 15:08 rustbot

:umbrella: The latest upstream changes (presumably 5097cfbd9239c36eb0f0a7389183c56005eac236) made this pull request unmergeable. Please resolve the merge conflicts.

Aug 03 '24 18:08 bors

Because the TBIBox interacts with Box and does allocations, it does not actually fit into stdarch - this will be moved into alloc, though there'll be an RFC coming first.

Sep 12 '24 15:09 mrkajetanp

:umbrella: The latest upstream changes (presumably 21a25573ed168af62b5f88264187243423b62472) made this pull request unmergeable. Please resolve the merge conflicts.

Oct 10 '24 15:10 bors