llvm/libclc/generic/lib/atomic/atomic_max.cl

#include <clc/clc.h>

#define IMPL(TYPE, AS, OP) \
_CLC_OVERLOAD _CLC_DEF TYPE atomic_max(volatile AS TYPE *p, TYPE val) { \
  return __sync_fetch_and_##OP(p, val); \
}

IMPL(int, global, max)
IMPL(unsigned int, global, umax)
IMPL(int, local, max)
IMPL(unsigned int, local, umax)
#undef IMPL