I’m not sure what you mean. Julia defines that pointer / pointer_from_objref returns an invalid Ptr for use from Julia (it can be used from C, although implicit conversion via ccall or Ref should generally be better / easier), and that unsafe_load / unsafe_store are unaligned operations that cannot operate on Julia objects (it’s undefined behavior if they alias in any way). So it’s not entirely just a question of how they benchmark, it’s simply that we define that the compiler may just ignore both if you intermix them (similar to how turning on TBAA in C can break non-standards-compliant code).
My recollection is that SIMD doesn’t usually handle early-exit, so compiler authors haven’t put much effort into trying to sort out which cases might be feasible to handle. LLVM may handle vectorizing conditional execution if it can turn it into a select operation or can identify an applicable sufflevector or mask – this seems to be rather difficult for it however, as I’ve mostly only observed it succeeding on fairly simple cases.