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

[Nathan Sidwell via cfe-commits]

urnathan wrote:

> On the LLVM side, there's very little interesting logic; it's basically just walking the tree of metadata nodes generated by clang. See https://llvm.org/docs/LangRef.html#tbaa-node-semantics . The hard part of the refactoring would just be adding an abstraction for the underlying information.

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?

I don't think it'd be that hard -- mostly mechanical. And I suspect only the scalar TBAA needs so moving, the structure-related stuff is sufficiently different to that strict-aliasing wants.

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

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