[llvm] [X86][SimplifyCFG][CodeGen] Support hoisting load/store with conditional faulting (PR #95515)

[Nikita Popov via llvm-commits]

nikic wrote:

@KanRobert Constant folding an all-true/all-false mask is the absolute minimum, but there are many other optimizations that do not happen. For example, even something as basic as https://llvm.godbolt.org/z/ajbhr6qEh does not seem to work.

While the masked load/store intrinsics are target-independent and old, they are also only used in specific situations and introduced fairly late in optimization (during vectorization), so ability to further optimize them has never been particularly important in the past.

https://github.com/llvm/llvm-project/pull/95515