OpenMP: Remove -fno-experimental-isel flag from testing

[arsenm]

Summary

This effectively reverts 6f9e25d3824fb7b03dc6a403e1962d80a9c88ebe.

I didn't follow the complete history, but it seems this was added due
to AArch64's output changing in some fallback. Blockaddress definitely
works now, so just remove this.

[Hahnfeld]

Fine for me if the OMPT tests now pass with GlobalISel

[arsenm]

2142dc31df05c46bc9294640715f6ebbed41f48c

openmp/cmake/DetectTestCompiler/CMakeLists.txt

 
 set(CMAKE_THREAD_PREFER_PTHREAD TRUE)
 set(THREADS_PREFER_PTHREAD_FLAG TRUE)
 find_package(Threads REQUIRED)
 
 set(C_FLAGS "${OpenMP_C_FLAGS} ${CMAKE_THREAD_LIBS_INIT}")
 set(CXX_FLAGS "${OpenMP_CXX_FLAGS} ${CMAKE_THREAD_LIBS_INIT}")
 
-# TODO: Implement blockaddress in GlobalISel and remove this flag!
-if (CMAKE_C_COMPILER_ID STREQUAL "Clang")
-  check_c_compiler_flag("-fno-experimental-isel" C_HAS_EXPERIMENTAL_ISEL_FLAG)
-  check_cxx_compiler_flag("-fno-experimental-isel" CXX_HAS_EXPERIMENTAL_ISEL_FLAG)
-  macro(add_experimental_isel_flag lang)
-    if (${lang}_HAS_EXPERIMENTAL_ISEL_FLAG)
-      set(${lang}_FLAGS "-fno-experimental-isel ${${lang}_FLAGS}")
-    endif()
-  endmacro(add_experimental_isel_flag)
-
-  add_experimental_isel_flag(C)
-  add_experimental_isel_flag(CXX)
-endif()
-
 check_c_compiler_flag("-fno-omit-frame-pointer" C_HAS_OMIT_FRAME_POINTER)
 check_cxx_compiler_flag("-fno-omit-frame-pointer" CXX_HAS_OMIT_FRAME_POINTER)
 
 set(OLD_CMAKE_REQUIRED_FLAGS ${CMAKE_REQUIRED_FLAGS})
 set(CMAKE_REQUIRED_FLAGS "-fsanitize=thread")
 check_c_compiler_flag("" C_HAS_TSAN_FLAG)
 check_cxx_compiler_flag("" CXX_HAS_TSAN_FLAG)
 set(CMAKE_REQUIRED_FLAGS ${OLD_CMAKE_REQUIRED_FLAGS})
 
 # Check if omp.h header exists for the test compiler
 check_include_file_cxx(omp.h CXX_HAS_OMP_H)
 check_include_file(omp.h C_HAS_OMP_H)
 
 write_compiler_information(C)
 write_compiler_information(CXX)

openmp/cmake/OpenMPTesting.cmake

else()
     set(OPENMP_TEST_COMPILER_THREAD_FLAGS "${CMAKE_THREAD_LIBS_INIT}")
   endif()
   if(TARGET tsan)
     set(OPENMP_TEST_COMPILER_HAS_TSAN_FLAGS 1)
   else()
     set(OPENMP_TEST_COMPILER_HAS_TSAN_FLAGS 0)
   endif()
   set(OPENMP_TEST_COMPILER_HAS_OMP_H 1)
-  # TODO: Implement blockaddress in GlobalISel and remove this flag!
-  set(OPENMP_TEST_COMPILER_OPENMP_FLAGS "-fopenmp ${OPENMP_TEST_COMPILER_THREAD_FLAGS} -fno-experimental-isel")
+  set(OPENMP_TEST_COMPILER_OPENMP_FLAGS "-fopenmp ${OPENMP_TEST_COMPILER_THREAD_FLAGS}")
   set(OPENMP_TEST_COMPILER_HAS_OMIT_FRAME_POINTER_FLAGS 1)
 endif()
 
 # Function to set compiler features for use in lit.
 function(set_test_compiler_features)
   if ("${OPENMP_TEST_COMPILER_ID}" STREQUAL "GNU")
     set(comp "gcc")
   elseif ("${OPENMP_TEST_COMPILER_ID}" STREQUAL "Intel")