64bit atomicAdd in CUDA

Question

I have a problem using atomicAdd under CUDA 7. atomicAdd is defined for " int ", " unsigned int " and " unsigned long long int " stating it uses "the 32 or 64 bit value".

In our code we use uint32_t and uint64_t for safety. However gcc defines this in the following way:

#if __WORDSIZE == 64
typedef unsigned long int   uint64_t;
#else
__extension__
typedef unsigned long long int  uint64_t;
#endif

So when I pass an uint64_t to atomicAdd it complains because it is not defined for " unsigned long int ".

Is it save to assume uint64_t == long long int for CUDA compilation as stated in the programming guide?

Answer 1

To answer that for future reference:

There are 2 options: Either use a typedef to define 64 bit cuda types like:

typedef long long int int64_cu
typedef unsigned long long int uint64_cu

And probably guard these by (boost-) static_asserts to be the same size(of)

Or as suggested by @Anastasiya Asadullayeva use a reinterpret_cast in the call which is better also guarded by a static_assert.