[PATCH] D15305: [CUDA] Do not allow dynamic initialization of global device side variables.

[Richard Smith via cfe-commits]

On Fri, Jan 15, 2016 at 4:22 PM, Artem Belevich <tra at google.com> wrote:
> tra added inline comments.
>
> ================
> Comment at: lib/CodeGen/CodeGenModule.cpp:2334
> @@ -2339,1 +2333,3 @@
> +      D->hasAttr<CUDASharedAttr>())
>      Init = llvm::UndefValue::get(getTypes().ConvertType(ASTTy));
> +  else if (!InitExpr) {
> ----------------
> rsmith wrote:
>> As this is a global variable, it should presumably still be statically zero-initialized.
> There is no way to initialize __shared__ variables. They are rough equivalent of local variables, only in this case CUDA allocates them per kernel invocation from a shared buffer with no guarantees regarding its contents.
>
> They used to be zero-initialized by compiler, but that was intentionally changed to undef in r245786 / http://reviews.llvm.org/D12241

That doesn't seem right. C++ guarantees zero-initialization for all
globals, prior to performing any other initialization.