[clang] [compiler-rt] [UBSan] Add -fsanitize=uninitialized-read check (ISO C 6.3.2.1p2) (PR #207529)

[Thurston Dang via cfe-commits]

thurstond wrote:

> Agreed, so what should be the best way to approach this issue currently. Would it be better to fold this into MSan, remove it from UBSan, or something else you suggest?

I suggest folding it into MSan.

There is somewhat of a precedent with `-fsanitize-memory-param-retval`, which optionally treats function parameters/return values as sinks. Analogously, there could be an `-fsanitize-memory-local-address-never-taken` (or something like that) that enables the additional sink behavior. The tricky part is that probably needs some information to be plumbed from the clang front-end through to MSan via the IR.

https://github.com/llvm/llvm-project/pull/207529