[PATCH] D44985: [CUDA] Let device-side shared variables be initialized with undef

[John McCall via Phabricator via cfe-commits]

rjmccall added inline comments.


================
Comment at: lib/CodeGen/CGDecl.cpp:235-240
+  if (Ty.getAddressSpace() != LangAS::opencl_local &&
+      !(getLangOpts().CUDA && getLangOpts().CUDAIsDevice &&
+        D.hasAttr<CUDASharedAttr>()))
     Init = EmitNullConstant(Ty);
   else
     Init = llvm::UndefValue::get(LTy);
----------------
tra wrote:
> This is too hard to read. Inverting it makes it somewhat easier to understand -- `either opencl_local or device-side CUDA shared are undef`.
> ```
>   if (Ty.getAddressSpace() == LangAS::opencl_local 
>       || (getLangOpts().CUDA && getLangOpts().CUDAIsDevice &&
>           D.hasAttr<CUDASharedAttr>()))
>     Init = llvm::UndefValue::get(LTy);
>   else
>     Init = EmitNullConstant(Ty);
> ```
> 
I assume getLangOpts().CUDAIsDevice implies getLangOpts().CUDA, so you really only need to check CUDAIsDevice.  But it might be faster still to just check for the attribute.


https://reviews.llvm.org/D44985