[PATCH] D35569: [ARM] Remove FeatureNoARM implies ModeThumb.

[Florian Hahn via Phabricator via llvm-commits]

fhahn added a comment.

There used to be an error message in ARMBaseTargetMachine if the selected ISA is ARM, but the CPU only supports Thumb. The check was removed in https://github.com/llvm-mirror/llvm/commit/26e9879a19bb6300bcbe5242681388d2a05e76cd by @echristo with a suggestion to do error reporting in the frontend. At the moment it does not look like Clang has access to the architecture/CPU feature information available in LLVM/lib/Target/ARM, which would be required to report the error in Clang. When we want to remove the error on a per-function basis, it gets even harder to do in the cases I mentioned above. To get proper error messages during LTO, we would have to add similar logic to the IR linker I think.

IMO it would make sense to have an error message in ARMBaseTargetMachine::getSubtargetImpl (as Eli suggested) rather than handing off the responsibilities to the frontends,. What do you think?


https://reviews.llvm.org/D35569