Reapply [openmp] [test] XFAIL many-microtask-args.c on ARM

On ARM, a C fallback version of __kmp_invoke_microtask is used,
which only handles up to a fixed number of arguments - while
many-microtask-args.c tests that the function can handle an
arbitrarily large number of arguments (the testcase produces 17
arguments).

On the CMake level, we can't add ${LIBOMP_ARCH} directly to
OPENMP_TEST_COMPILER_FEATURES in OpenMPTesting.cmake, since
that file is parsed before LIBOMP_ARCH is set. Instead
convert the feature list into a proper CMake list, and append
${LIBOMP_ARCH} into it before serializing it to an Python array.

Reapply: Make sure OPENMP_TEST_COMPILER_FEATURES is defined
properly in all other test subdirectories other than
runtime/test too.

Differential Revision: https://reviews.llvm.org/D138738

openmp/cmake/OpenMPTesting.cmake

@@ -159,6 +159,20 @@ else()
 endif()
 
 # Function to set compiler features for use in lit.
+function(update_test_compiler_features)
+  set(FEATURES "[")
+  set(first TRUE)
+  foreach(feat IN LISTS OPENMP_TEST_COMPILER_FEATURE_LIST)
+    if (NOT first)
+      string(APPEND FEATURES ", ")
+    endif()
+    set(first FALSE)
+    string(APPEND FEATURES "'${feat}'")
+  endforeach()
+  string(APPEND FEATURES "]")
+  set(OPENMP_TEST_COMPILER_FEATURES ${FEATURES} PARENT_SCOPE)
+endfunction()
+
 function(set_test_compiler_features)
   if ("${OPENMP_TEST_COMPILER_ID}" STREQUAL "GNU")
     set(comp "gcc")
@@ -168,9 +182,10 @@ function(set_test_compiler_features)
     # Just use the lowercase of the compiler ID as fallback.
     string(TOLOWER "${OPENMP_TEST_COMPILER_ID}" comp)
   endif()
-  set(OPENMP_TEST_COMPILER_FEATURES "['${comp}', '${comp}-${OPENMP_TEST_COMPILER_VERSION_MAJOR}', '${comp}-${OPENMP_TEST_COMPILER_VERSION_MAJOR_MINOR}', '${comp}-${OPENMP_TEST_COMPILER_VERSION}']" PARENT_SCOPE)
+  set(OPENMP_TEST_COMPILER_FEATURE_LIST ${comp} ${comp}-${OPENMP_TEST_COMPILER_VERSION_MAJOR} ${comp}-${OPENMP_TEST_COMPILER_VERSION_MAJOR_MINOR} ${comp}-${OPENMP_TEST_COMPILER_VERSION} PARENT_SCOPE)
 endfunction()
 set_test_compiler_features()
+update_test_compiler_features()
 
 # Function to add a testsuite for an OpenMP runtime library.
 function(add_openmp_testsuite target comment)

openmp/runtime/test/CMakeLists.txt

@@ -24,6 +24,9 @@ macro(pythonize_bool var)
   endif()
 endmacro()
 
+list(APPEND OPENMP_TEST_COMPILER_FEATURE_LIST "${LIBOMP_ARCH}")
+update_test_compiler_features()
+
 pythonize_bool(LIBOMP_USE_HWLOC)
 pythonize_bool(LIBOMP_OMPT_SUPPORT)
 pythonize_bool(LIBOMP_OMPT_OPTIONAL)

openmp/runtime/test/misc_bugs/many-microtask-args.c

@@ -1,6 +1,11 @@
 // RUN: %libomp-compile-and-run
 #include <stdio.h>
 
+// This test fails with Clang unless __kmp_invoke_microtask supports at least
+// 17 arguments. On ARM, the fallback C implementation of __kmp_invoke_microtask
+// is used, and that one only currently supports up to 15 arguments.
+// XFAIL: arm
+
 int main()
 {