[llvm] Introduce DIExpression::foldConstantMath() (PR #71718)

[Jeremy Morse via llvm-commits]

https://github.com/jmorse commented:

Just to record that I'm really glad this is being addressed; it feels like it could probably be made more readable and there are some ideas for that in reviews, I don't want to wade in too. My 2 cents from a high level -- transforming from old-expression into a new-expression rather than editing in-place might be easier.

https://github.com/llvm/llvm-project/pull/71718