[llvm] [ValueTracking] Handle not cond to assume. (PR #127140)

[Andreas Jonson via llvm-commits]

andjo403 wrote:

> What would happen if we treat any instruction that feeds into the assume as ephemeral, even if it has other users?

I maybe missunderstad your question but is that not already done 
https://github.com/llvm/llvm-project/blob/70b95ca6dbee7036dcfa5995ff804471fd7e8c2a/llvm/lib/Analysis/ValueTracking.cpp#L448-L452 
the problem is that it only is the argument to the assume function that ignore other users not all instructions that builds up the condition. 
added handling for the not as that is the only logical operation that is add to the `AssumptionCache`  as and/or is split up before adding.

https://github.com/llvm/llvm-project/pull/127140