[PATCH] D21701: [AMDGPU] Fix warning

[Konstantin Zhuravlyov via llvm-commits]

kzhuravl added a comment.

I am getting this warning when building without `default`:

  /home/kzhuravl/Lightning/llvm/lib/Target/AMDGPU/AMDGPUInstrInfo.cpp: In function â?~SIEncodingFamily subtargetEncodingFamily(const llvm::AMDGPUSubtarget&)â?T:
  /home/kzhuravl/Lightning/llvm/lib/Target/AMDGPU/AMDGPUInstrInfo.cpp:160:1: warning: control reaches end of non-void function [-Wreturn-type]
   }
   ^

I am not getting a warning with `default`, which makes sense to me.

Underlying type of an unscoped enum is some integral type (int, unsigned int, etc... implementation-defined). So, I do not think, that switching over all defined enum values is enough:

- What happens if, for some reason, `ST.getGeneration()` returns an undefined enum value (for example, some garbage)? - undefined behavior.
- What happens if we add a new enum value, and forget to add it to a switch statement? - undefined behavior.

Someone can argue that above 2 cases can never happen, hence it is a warning, not a compilation error. But I'd rather know that unreachable will be executed if something goes wrong.

Please, correct me if I am wrong.

I am not sure why you experience the reverse behavior. Do you have any other modified files? Can you paste the warning you are getting?


http://reviews.llvm.org/D21701