Call by reference with kernel function parameters (NVCC in CUDA 2.2)

Accelerated Computing CUDA CUDA Programming and Performance
1

Hi,

yesterday I have upgraded my CUDA based framework from 2.1 to 2.2. Unfortunately I encounter some problems related to reference kernel parameters.

Think of this example:

__global__ void testKernel(int& i)

{ i = 5; }

The NVCC from 2.1 accepts this code and generates working code. The 2.2 version generates the following error message:

Error	1	error C2664: '__device_stub__Z10testKerneliRiRf' : cannot convert parameter 2 from 'int' to 'int *'	C:\Temp\tmpxft_0000014c_00000000-3_test1.cudafe1.stub.c	15

Maybe this behavior is related to recent changes like…

o The default compilation mode for host code is now C++. To restore the old behavior, use the option --host-compilation=c

…because with C compilation mode NVCC accepts the code.

Can someone confirm this behavior, and if so, confirm this is a bug?

Btw… I’m using the release version of 2.2 CUDA with Visual Studio 2005.

Thx,

Marcel

2

Are use passing a value by reference from host to device? How is that even possible?

3

This is possible via CuPP framework, since the copy operations are done by the underlying layer.
Unfortunately nvcc no longer seems to accepts passing things via reference.