[llvm] [IndVarSimplify] Allow predicateLoopExit on some loops with local writes (PR #155901)

[Florian Mayer via llvm-commits]

fmayer wrote:

> This is a really interesting idea. The basic approach can be phrased as allowing a trap to be taken early without all side effects in program order before the trap becoming visible. You restrict this to side effects for which another thread relying on them would already be UB.

This was my follow up idea to this CL. This change does not allow side effects, it just makes allowance for writes to local variables.

But I was thinking of exactly this as a follow up: kind of like Minority Report, we trap in advance if we know we are going to hit UB (**but not a normal trap**).

https://github.com/llvm/llvm-project/pull/155901