[clang] [llvm] [CHERI][RISCV][MC] Add support for aligning and tail-padding globals for precise bounds tracking on CHERI targets. (PR #203872)

[Owen Anderson via cfe-commits]

resistor wrote:

Reimplemented this on top of https://github.com/llvm/llvm-project/pull/121957

There is one significant behavioral change introduced for MTE, which we need to confirm is correct. For CHERI, we retained the original size in the symbol size in the ELF (i.e. excluding the tail padding from it), while the existing MTE behavior add the padding size into the symbol size. The version currently the PR uses the CHERI behavior, which seems more semantically correct to me, but I'd like to hear from someone who knows MTE to comment on it.

https://github.com/llvm/llvm-project/pull/203872