[clang] [llvm] Add FramePointerKind::NonLeafNoReserve (PR #163775)

[Eli Friedman via llvm-commits]

efriedma-quic wrote:

I guess my remaining question is if -fno-omit-frame-pointer should imply -mreserve-frame-pointer-reg by default. I can see why you'd want it off by default for gcc compatibility.  But I suspect most users enabling frame pointers would be happier if it was on.  The primary reason people enable frame pointers is to use frame chains to compute a stack trace, and clobbering the frame pointer breaks that.

CC @pinskia

https://github.com/llvm/llvm-project/pull/163775