-ddump-llvm forces use of LLVM backend
While looking at #20735 (closed) I was surprised and confused to find that my 9.4.0 compiler was using the LLVM backend, despite being equipped with an NCG. After quite a bit of head-scratching I found the cause: -ddump-llvm
unconditionally changes the backend to LLVM.
This is extremely surprising and is a very large foot-gun since no other -ddump-*
flag changes GHC's behavior. I will remove this behavior.