[OpenMP][libomp] do not try to dlopen libmemkind on macOS

[danieljdouglas-deco]

Summary

libmemkind is only available for linux
calling dlopen here can also be problematic in a client app that fork'ed

[jlpeyton]

LGTM.

For future patches, look at https://llvm.org/docs/Phabricator.html#requesting-a-review-via-the-web-interface for uploading diff with as much context as possible.

[jlpeyton]

Sorry, I should have asked this before, do you need me to commit this on your behalf?

[danieljdouglas-deco]

In D126579#3553633, @jlpeyton wrote:

Sorry, I should have asked this before, do you need me to commit this on your behalf?

Ahh, yes please. I don't believe I have the permissions to do that. Thanks for your help!

openmp/runtime/src/kmp_alloc.cpp

#define KMP_IS_TARGET_MEM_SPACE(MS)                                            \
   (MS == llvm_omp_target_host_mem_space ||                                     \
    MS == llvm_omp_target_shared_mem_space ||                                   \
    MS == llvm_omp_target_device_mem_space)
 #define KMP_IS_TARGET_MEM_ALLOC(MA)                                            \
   (MA == llvm_omp_target_host_mem_alloc ||                                     \
    MA == llvm_omp_target_shared_mem_alloc ||                                   \
    MA == llvm_omp_target_device_mem_alloc)
 
-#if KMP_OS_UNIX && KMP_DYNAMIC_LIB
+#if KMP_OS_UNIX && KMP_DYNAMIC_LIB && !KMP_OS_DARWIN
 static inline void chk_kind(void ***pkind) {
   KMP_DEBUG_ASSERT(pkind);
   if (*pkind) // symbol found
     if (kmp_mk_check(**pkind)) // kind not available or error
       *pkind = NULL;
 }
 #endif
 
 void __kmp_init_memkind() {
 // as of 2018-07-31 memkind does not support Windows*, exclude it for now
-#if KMP_OS_UNIX && KMP_DYNAMIC_LIB
+#if KMP_OS_UNIX && KMP_DYNAMIC_LIB && !KMP_OS_DARWIN
   // use of statically linked memkind is problematic, as it depends on libnuma
   kmp_mk_lib_name = "libmemkind.so";
   h_memkind = dlopen(kmp_mk_lib_name, RTLD_LAZY);
   if (h_memkind) {
     kmp_mk_check = (int (*)(void *))dlsym(h_memkind, "memkind_check_available");
     kmp_mk_alloc =
         (void *(*)(void *, size_t))dlsym(h_memkind, "memkind_malloc");
     kmp_mk_free = (void (*)(void *, void *))dlsym(h_memkind, "memkind_free");