[clang] [clang] Strict aliasing warning ala GCC [PR50066] (PR #74155)

[Eli Friedman via cfe-commits]

efriedma-quic wrote:

> IIUC you're suggesting movint the TBAA data origination from CodeGen into (probably) Sema and/or TargetInfo and then deriving the LLVM info in CodeGen from that. I.e. keep once source of truth, but move where it is?

Right; move the core computation to AST, and then the CodeGen bits would just translate that data to LLVM IR.

> Although you don't explicitly say it, the implication is you'd be ameanable to such an approach?

TBAA categorization is semantic information, so I think it makes sense to make it accessible outside CodeGen, yes.

https://github.com/llvm/llvm-project/pull/74155