[OpenMP] Fix two usm tests for amdgpus.

Some are missing setting of HSA_XNACK=1 environment variable, used to enable unified memory support on amdgpu's when it's not been set at kernel boot time.
Some others needed to be marked as supporting unified_shared_memory in the lit test harness.

openmp/libomptarget/test/lit.cfg

@@ -117,7 +117,10 @@ if config.libomptarget_current_target.startswith('nvptx'):
     # If the architecture is invalid, assume it is supported.
     supports_unified_shared_memory = True
 if config.libomptarget_current_target.startswith('amdgcn'):
-    supports_unified_shared_memory = False
+    if not (config.amdgpu_test_arch == "gfx908" or
+            config.amdgpu_test_arch == "gfx90a" or
+            config.amdgpu_test_arch == "gfx942") :
+       supports_unified_shared_memory = False
 if supports_unified_shared_memory:
    config.available_features.add('unified_shared_memory')
 

openmp/libomptarget/test/lit.site.cfg.in

@@ -10,6 +10,7 @@ config.test_extra_flags = "@OPENMP_TEST_FLAGS@"
 config.cuda_path = "@CUDA_TOOLKIT_ROOT_DIR@"
 config.cuda_libdir = "@CUDA_LIBDIR@"
 config.cuda_test_arch = "@LIBOMPTARGET_DEP_CUDA_ARCH@"
+config.amdgpu_test_arch = "@LIBOMPTARGET_AMDGPU_DETECTED_ARCH_LIST@"
 config.libomptarget_obj_root = "@CMAKE_CURRENT_BINARY_DIR@/@CURRENT_TARGET@"
 config.library_dir = "@LIBOMPTARGET_LIBRARY_DIR@"
 config.llvm_library_dir = "@LIBOMPTARGET_LLVM_LIBRARY_DIR@"

openmp/libomptarget/test/unified_shared_memory/api.c

@@ -1,10 +1,9 @@
-// RUN: %libomptarget-compile-run-and-check-generic
+// RUN: %libomptarget-compile-generic
+// RUN: env HSA_XNACK=1 \
+// RUN: %libomptarget-run-generic | %fcheck-generic
 // XFAIL: nvptx64-nvidia-cuda
 // XFAIL: nvptx64-nvidia-cuda-LTO
 
-// Fails on amdgpu with error: GPU Memory Error
-// UNSUPPORTED: amdgcn-amd-amdhsa
-
 #include <omp.h>
 #include <stdio.h>
 

openmp/libomptarget/test/unified_shared_memory/close_enter_exit.c

@@ -1,11 +1,11 @@
-// RUN: %libomptarget-compile-run-and-check-generic
+// RUN: %libomptarget-compile-generic
+// RUN: env HSA_XNACK=1 \
+// RUN: %libomptarget-run-generic | %fcheck-generic
 
 // REQUIRES: unified_shared_memory
 // UNSUPPORTED: clang-6, clang-7, clang-8, clang-9
 
-// Fails on amdgpu with error: GPU Memory Error
 // Fails on nvptx with error: an illegal memory access was encountered
-// XFAIL: amdgcn-amd-amdhsa
 // XFAIL: nvptx64-nvidia-cuda
 // XFAIL: nvptx64-nvidia-cuda-LTO