[flang] [clang] [Flang][Clang] Add support for frame pointers in Flang Driver (PR #72146)

[Tom Eccles via cfe-commits]

https://github.com/tblah requested changes to this pull request.

While I guess it isn't wrong, it feels weird do declare all of the storage on the front end driver side, but never set them (the member of the CodeGenOpttions class, the changes in Frontend/CodeGenOptions.h, adding it to MLIRToLLVMPassPipelineConfig.

This might be a bit nitpicky but I would either remove these changes or add frontend driver code to read the argument and set it in the MLIRToLLVMPassPipelineConfig and CodeGenOptions (although this would be untestable so others may disagree).

With regard to the front end driver stuff, I don't know if we gain anything by adding a flang specific definition of the enum in CodeGenOptions.h, as we will just convert to an llvm::FramePointerKind to populate MLIRToLLVMPassPipelineConfig. If you're sure that the llvm version is the one you want to use in MLIRToLLVMPassPipelineConfig, then just use that same type in flang::CodeGenOptions too.

https://github.com/llvm/llvm-project/pull/72146