[flang] [llvm] [clang-tools-extra] [clang] [flang] Pass to add frame pointer attribute (PR #74598)

[Kiran Chandramohan via cfe-commits]

kiranchandramohan wrote:

> > llc has a --frame-pointer option, so there is likely a way to pass this option to the llvm codegen as a global option instead of setting it on all function at the MLIR level if the only goal is to propagate it to llvm backend.
> 
> I just discussed a bit with @vzakhari and one advantage of setting it per function is to later be able to merge llvm IR files compiled with different options. That would explain why clang does it. I would still add nothing if the option is None since this is the default, but seems OK to me to decorate the functions as you are doing based on this argument.

@jeanPerier just checking whether you are OK with this pass being here or would prefer it to be in LLVM dialect?

https://github.com/llvm/llvm-project/pull/74598