[OpenMP][libomp] Detect if test compiler has omp.h

[jlpeyton]

Summary

omp50_taskdep_depobj.c relies on the test compiler's omp.h file.
If the test compiler does not have an omp.h file, then use the one
within the build tree.

Fixes: https://github.com/llvm/llvm-project/issues/56820

[Meinersbur]

Rather than disabling the test, did you consider adding an -I${CMAKE_CURRENT_BINARY_DIR}/runtime/src (where omp.h resides) to the clang test flags? Even if there is an omp.h already on the system, libomp's header should be used instead since it may contain new symbols not yet present in the system's omp.h. It might even be -isystem to treat it like a system header.

[jlpeyton]

In D131000#3694188, @Meinersbur wrote:

Rather than disabling the test, did you consider adding an -I${CMAKE_CURRENT_BINARY_DIR}/runtime/src (where omp.h resides) to the clang test flags? Even if there is an omp.h already on the system, libomp's header should be used instead since it may contain new symbols not yet present in the system's omp.h. It might even be -isystem to treat it like a system header.

The test doesn't become disabled. It uses the generated omp.h instead. This is the only test that attempts to use the system omp.h (or test compiler's omp.h). The original purpose was to test GCC compatibility of depobj which GCC defines differently than our omp.h.

[mgorny]

Thanks. I can confirm that this fixes the immediate problem for me.

omp50_taskdep_depobj.c relies on the test compiler's omp.h file. If the test compiler does not have an omp.h file, then the one within the build tree.

You seem to missing a verb in the commit message.

[Meinersbur]

In D131000#3694319, @jlpeyton wrote:

The test doesn't become disabled. It uses the generated omp.h instead. This is the only test that attempts to use the system omp.h (or test compiler's omp.h). The original purpose was to test GCC compatibility of depobj which GCC defines differently than our omp.h.

Indeed I missed that %flags-use-compiler-omp-h is specifically to test not using libomp's own omp.h.

openmp/cmake/DetectTestCompiler/CMakeLists.txt

 cmake_minimum_required(VERSION 3.13.4)
 project(DetectTestCompiler C CXX)
 
 include(CheckCCompilerFlag)
 include(CheckCXXCompilerFlag)
+include(CheckIncludeFile)
+include(CheckIncludeFileCXX)
 
 function(write_compiler_information lang)
   set(information "${CMAKE_${lang}_COMPILER}")
   set(information "${information}\\;${CMAKE_${lang}_COMPILER_ID}")
   set(information "${information}\\;${CMAKE_${lang}_COMPILER_VERSION}")
   set(information "${information}\\;${${lang}_FLAGS}")
   set(information "${information}\\;${${lang}_HAS_TSAN_FLAG}")
   set(information "${information}\\;${${lang}_HAS_OMIT_FRAME_POINTER}")
+  set(information "${information}\\;${${lang}_HAS_OMP_H}")
   file(WRITE ${CMAKE_CURRENT_BINARY_DIR}/${lang}CompilerInformation.txt ${information})
 endfunction(write_compiler_information)
 
 find_package(OpenMP)
 if (NOT OpenMP_Found)
   set(OpenMP_C_FLAGS "-fopenmp")
   set(OpenMP_CXX_FLAGS "-fopenmp")
 endif()
if (CMAKE_C_COMPILER_ID STREQUAL "Clang")
 
   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(CMAKE_REQUIRED_FLAGS "-fsanitize=thread")
+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

 macro(extract_test_compiler_information lang file)
   file(READ ${file} information)
   list(GET information 0 path)
   list(GET information 1 id)
   list(GET information 2 version)
   list(GET information 3 openmp_flags)
   list(GET information 4 has_tsan_flags)
   list(GET information 5 has_omit_frame_pointer_flags)
+  list(GET information 6 has_omp_h)
 
   set(OPENMP_TEST_${lang}_COMPILER_PATH ${path})
   set(OPENMP_TEST_${lang}_COMPILER_ID ${id})
   set(OPENMP_TEST_${lang}_COMPILER_VERSION ${version})
   set(OPENMP_TEST_${lang}_COMPILER_OPENMP_FLAGS ${openmp_flags})
   set(OPENMP_TEST_${lang}_COMPILER_HAS_TSAN_FLAGS ${has_tsan_flags})
   set(OPENMP_TEST_${lang}_COMPILER_HAS_OMIT_FRAME_POINTER_FLAGS ${has_omit_frame_pointer_flags})
+  set(OPENMP_TEST_${lang}_COMPILER_HAS_OMP_H ${has_omp_h})
 endmacro()
 
 # Function to set variables with information about the test compiler.
 function(set_test_compiler_information dir)
   extract_test_compiler_information(C ${dir}/CCompilerInformation.txt)
   extract_test_compiler_information(CXX ${dir}/CXXCompilerInformation.txt)
   if (NOT("${OPENMP_TEST_C_COMPILER_ID}" STREQUAL "${OPENMP_TEST_CXX_COMPILER_ID}" AND
           "${OPENMP_TEST_C_COMPILER_VERSION}" STREQUAL "${OPENMP_TEST_CXX_COMPILER_VERSION}"))
     message(STATUS "Test compilers for C and C++ don't match.")
     message(WARNING "The check targets will not be available!")
     set(ENABLE_CHECK_TARGETS FALSE PARENT_SCOPE)
   else()
     set(OPENMP_TEST_COMPILER_ID "${OPENMP_TEST_C_COMPILER_ID}" PARENT_SCOPE)
     set(OPENMP_TEST_COMPILER_VERSION "${OPENMP_TEST_C_COMPILER_VERSION}" PARENT_SCOPE)
     set(OPENMP_TEST_COMPILER_OPENMP_FLAGS "${OPENMP_TEST_C_COMPILER_OPENMP_FLAGS}" PARENT_SCOPE)
     set(OPENMP_TEST_COMPILER_HAS_TSAN_FLAGS "${OPENMP_TEST_C_COMPILER_HAS_TSAN_FLAGS}" PARENT_SCOPE)
     set(OPENMP_TEST_COMPILER_HAS_OMIT_FRAME_POINTER_FLAGS "${OPENMP_TEST_C_COMPILER_HAS_OMIT_FRAME_POINTER_FLAGS}" PARENT_SCOPE)
+    set(OPENMP_TEST_COMPILER_HAS_OMP_H "${OPENMP_TEST_C_COMPILER_HAS_OMP_H}" PARENT_SCOPE)
 
     # Determine major version.
     string(REGEX MATCH "[0-9]+" major "${OPENMP_TEST_C_COMPILER_VERSION}")
     string(REGEX MATCH "[0-9]+\\.[0-9]+" majorminor "${OPENMP_TEST_C_COMPILER_VERSION}")
     set(OPENMP_TEST_COMPILER_VERSION_MAJOR "${major}" PARENT_SCOPE)
     set(OPENMP_TEST_COMPILER_VERSION_MAJOR_MINOR "${majorminor}" PARENT_SCOPE)
   endif()
 endfunction()
else()
   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_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")

openmp/runtime/test/CMakeLists.txt

 
 pythonize_bool(LIBOMP_USE_HWLOC)
 pythonize_bool(LIBOMP_OMPT_SUPPORT)
 pythonize_bool(LIBOMP_OMPT_OPTIONAL)
 pythonize_bool(LIBOMP_HAVE_LIBM)
 pythonize_bool(LIBOMP_HAVE_LIBATOMIC)
 pythonize_bool(OPENMP_STANDALONE_BUILD)
 pythonize_bool(OPENMP_TEST_COMPILER_HAS_OMIT_FRAME_POINTER_FLAGS)
+pythonize_bool(OPENMP_TEST_COMPILER_HAS_OMP_H)
 
 add_library(ompt-print-callback INTERFACE)
 target_include_directories(ompt-print-callback INTERFACE ${CMAKE_CURRENT_SOURCE_DIR}/ompt)
 
 
 add_openmp_testsuite(check-libomp "Running libomp tests" ${CMAKE_CURRENT_BINARY_DIR} DEPENDS omp)
 # Add target check-ompt, but make sure to not add the tests twice to check-openmp.
 add_openmp_testsuite(check-ompt "Running OMPT tests" ${CMAKE_CURRENT_BINARY_DIR}/ompt EXCLUDE_FROM_CHECK_ALL DEPENDS omp)
 
 # Configure the lit.site.cfg.in file
 set(AUTO_GEN_COMMENT "## Autogenerated by libomp configuration.\n# Do not edit!")
 configure_file(lit.site.cfg.in lit.site.cfg @ONLY)

openmp/runtime/test/lit.cfg

 config.substitutions.append(("%libomp-c99-compile", \
     "%clang %openmp_flags %flags -std=c99 %s -o %t" + libs))
 config.substitutions.append(("%libomp-run", "%t"))
 config.substitutions.append(("%clangXX", config.test_cxx_compiler))
 config.substitutions.append(("%clang", config.test_c_compiler))
 config.substitutions.append(("%openmp_flags", config.test_openmp_flags))
 # %flags-use-compiler-omp-h allows us to use the test compiler's omp.h file which
 # may have different definitions of structures than our omp.h file.
-if config.is_standalone_build:
+if config.is_standalone_build and config.test_compiler_has_omp_h:
     config.substitutions.append(("%flags-use-compiler-omp-h",
         config.test_flags_use_compiler_omp_h))
 else:
     # If testing the runtime within an LLVM tree, then always include omp.h
     # directory associated with the new clang compiler.
     config.substitutions.append(("%flags-use-compiler-omp-h",
         config.test_flags))
 config.substitutions.append(("%flags", config.test_flags))

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

 @AUTO_GEN_COMMENT@
 
 config.test_c_compiler = "@OPENMP_TEST_C_COMPILER@"
 config.test_cxx_compiler = "@OPENMP_TEST_CXX_COMPILER@"
 config.test_compiler_features = @OPENMP_TEST_COMPILER_FEATURES@
+config.test_compiler_has_omp_h = @OPENMP_TEST_COMPILER_HAS_OMP_H@
 config.test_filecheck = "@OPENMP_FILECHECK_EXECUTABLE@"
 config.test_not = "@OPENMP_NOT_EXECUTABLE@"
 config.test_openmp_flags = "@OPENMP_TEST_OPENMP_FLAGS@"
 config.test_extra_flags = "@OPENMP_TEST_FLAGS@"
 config.libomp_obj_root = "@CMAKE_CURRENT_BINARY_DIR@"
 config.library_dir = "@LIBOMP_LIBRARY_DIR@"
 config.omp_header_directory = "@LIBOMP_BINARY_DIR@/src"
 config.operating_system = "@CMAKE_SYSTEM_NAME@"