34ff90ad5d
As Wei Mi is reporting in post-commit review https://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20201116/853479.html teaching -reassociate about add-like-or's (70472f3) results in breaking apart load widening patterns, and reassociating them. For now, simply exclude any such `or` that appears to be a root of load widening idiom from the or->add transformation. Note that the heuristic is greedy, it doesn't ensure that loads can *actually* be widened into a single load.