5 Replies Latest reply on Aug 4, 2014 2:37 AM by pinform

    int64 atom_cmpxchg on AMD 6168 CPU


      The OpenCL code below fails to compile for an AMD 6168 CPU. AMD_APP version 2.8. Note the compiler does not complain about cl_khr_int64_base_atomics, so I have to assume they are supported for the 6168. The compiler error is listed before the code, and note that the signature I'm trying to use for atomic_cmpxchg is listed in the OpenCL spec.



      Thanks for any help!




      2: clBuildProgram failed:

      2: "/tmp/OCLOciay5.cl", line 46: error: no instance of overloaded function

      2:           "atomic_cmpxchg" matches the argument list

      2:             argument types are: (volatile __global ulong *, ulong, ulong)

      2:     } while (atomic_cmpxchg((volatile __global unsigned long *)source,

      2:              ^


      2: 1 error detected in the compilation of "/tmp/OCLOciay5.cl".


      2: Frontend phase failed compilation.


      2: -D__OCL_AMD__ -I/home/wohlbier/Chicoma/chicoma/config/../src/util -Werror -cl-strict-aliasing -cl-fast-relaxed-math -cl-std=CL1.1





      // enable int64 atomics

      #pragma OPENCL EXTENSION cl_khr_int64_base_atomics : enable


      typedef double real_t;


      inline void atomic_real_add(volatile __global real_t * source,

                        const real_t operand) {

        union {

          unsigned long intVal;

          real_t realVal;

        } newVal;

        union {

          unsigned long intVal;

          real_t realVal;

        } prevVal;


        do {

          prevVal.realVal = *source;

          newVal.realVal = prevVal.realVal + operand;

        } while (atomic_cmpxchg((volatile __global unsigned long *)source,

                      prevVal.intVal, newVal.intVal) != prevVal.intVal);