[clang] [llvm] [Loads] Check context instruction for context-sensitive derefability (PR #109277)

[Nikita Popov via cfe-commits]

nikic wrote:

> Is it even possible for `isSafeToSpeculativelyExecute` to return `true` now with the default (nullptr) CtxI for loads? Can `isDereferenceableAndAlignedPointer` just short-circuit to `false` with null CtxI?

Yes, it's possible for anything where the derefability is not context-sensitive (like globals, dereferenceable arguments, allocas, etc).

https://github.com/llvm/llvm-project/pull/109277