[llvm] [LangRef] Do not make align imply dereferenceability (PR #158062)

[Nuno Lopes via llvm-commits]

nunoplopes wrote:

What convinced me was that example of merging multiple consecutive stores into one. We need that to be correct, irrespective of the alignment. So this change to langref doesn't make things any more difficult.

But I'm concerned about how prevalent might be the idea that a memory operation only touches a single object. We need to audit alias analysis to make sure there aren't decisions being made based on each operation touching a single object. Anyway, but that's a worry for another time.

Feel free to merge this. Thanks and sorry for keeping you waiting.

https://github.com/llvm/llvm-project/pull/158062