[llvm] [mlir] [polly] [IR] Only allow lifetime.start/end on allocas (PR #149310)

[Nikita Popov via llvm-commits]

nikic wrote:

> Should we add an assertion failure to this now? We should always be able to find the alloca for a lifetime after this change: https://github.com/llvm/llvm-project/blob/main/llvm/lib/Transforms/Utils/MemoryTaggingSupport.cpp#L158

I'm going to remove various code dealing with unanalyzable lifetimes in a followup.

https://github.com/llvm/llvm-project/pull/149310