Add LIBOMP_ENABLE_SHARED option for CMake

When building executables for Cray supercomputers, statically-linked executables
are preferred. This patch makes it possible to build the OpenMP runtime as an
archive for building statically-linked executables.  The patch adds the flag
LIBOMP_ENABLE_SHARED, which defaults to true. When true, a build of the OpenMP
runtime yields dynamic libraries. When false, a build of the OpenMP runtime
yields static libraries. There is no setting that allows both kinds of libraries
to be built.

Patch by John Mellor-Crummey

Differential Revision: http://reviews.llvm.org/D16525

llvm-svn: 259817

openmp/runtime/Build_With_CMake.txt

@@ -143,6 +143,11 @@ symbols are supported (Linux, some BSD* variants).  It is off
 by default for Windows and Mac, but on for other Unix based operating
 systems.
 
+-DLIBOMP_ENABLE_SHARED=on|off
+Shared library instead of static library? (Note: static libraries are not
+supported on Windows). If LIBOMP_ENABLE_SHARED is off, then static OpenMP
+libraries will be built instead of dynamic ones.
+
 -DLIBOMP_OMPT_SUPPORT=off|on
 Should OMPT support be included in the build? (Not supported on Windows)
 If LIBOMP_OMPT_SUPPORT is off, then both ompt_blame and ompt_trace are ignored.

openmp/runtime/CMakeLists.txt

@@ -277,6 +277,14 @@ if(LIBOMP_STATS)
   set(LIBOMP_USE_STDCPPLIB TRUE)
 endif()
 
+# Shared library can be switched to a static library
+set(LIBOMP_ENABLE_SHARED TRUE CACHE BOOL
+  "Shared library instead of static library?")
+
+if(WIN32 AND NOT LIBOMP_ENABLE_SHARED)
+  libomp_error_say("Static libraries requested but not available on Windows")
+endif()
+
 # OMPT-support
 set(LIBOMP_OMPT_DEBUG FALSE CACHE BOOL
   "Trace OMPT initialization?")
@@ -304,7 +312,18 @@ if(${STUBS_LIBRARY})
   set(LIBOMP_DEFAULT_LIB_NAME ${LIBOMP_DEFAULT_LIB_NAME}stubs)
 endif()
 set(LIBOMP_LIB_NAME ${LIBOMP_DEFAULT_LIB_NAME} CACHE STRING "Base OMP library name")
-set(LIBOMP_LIB_FILE ${LIBOMP_LIB_NAME}${CMAKE_SHARED_LIBRARY_SUFFIX})
+
+if(${LIBOMP_ENABLE_SHARED})
+  set(LIBOMP_LIBRARY_SUFFIX ${CMAKE_SHARED_LIBRARY_SUFFIX})
+  set(LIBOMP_LIBRARY_KIND SHARED) 
+  set(LIBOMP_INSTALL_KIND LIBRARY) 
+else()
+  set(LIBOMP_LIBRARY_SUFFIX ${CMAKE_STATIC_LIBRARY_SUFFIX})
+  set(LIBOMP_LIBRARY_KIND STATIC) 
+  set(LIBOMP_INSTALL_KIND ARCHIVE) 
+endif()
+
+set(LIBOMP_LIB_FILE ${LIBOMP_LIB_NAME}${LIBOMP_LIBRARY_SUFFIX})
 
 # Print configuration after all variables are set.
 if(${LIBOMP_STANDALONE_BUILD})
@@ -315,7 +334,8 @@ if(${LIBOMP_STANDALONE_BUILD})
   endif()
   libomp_say("Build Type           -- ${CMAKE_BUILD_TYPE}")
   libomp_say("OpenMP Version       -- ${LIBOMP_OMP_VERSION}")
-  libomp_say("Lib Type             -- ${LIBOMP_LIB_TYPE}")
+  libomp_say("Library Kind         -- ${LIBOMP_LIBRARY_KIND}")
+  libomp_say("Library Type         -- ${LIBOMP_LIB_TYPE}")
   libomp_say("Fortran Modules      -- ${LIBOMP_FORTRAN_MODULES}")
   # will say development if all zeros
   if(${LIBOMP_VERSION_BUILD} STREQUAL 00000000)

openmp/runtime/src/CMakeLists.txt

@@ -136,7 +136,9 @@ endif()
 
 # Add the OpenMP library
 libomp_get_ldflags(LIBOMP_CONFIGURED_LDFLAGS)
-add_library(omp SHARED ${LIBOMP_SOURCE_FILES})
+
+add_library(omp ${LIBOMP_LIBRARY_KIND} ${LIBOMP_SOURCE_FILES})
+
 set_target_properties(omp PROPERTIES
   PREFIX "" SUFFIX "" OUTPUT_NAME "${LIBOMP_LIB_FILE}"
   LINK_FLAGS "${LIBOMP_CONFIGURED_LDFLAGS}"
@@ -156,9 +158,9 @@ endif()
 if(NOT WIN32)
   add_custom_command(TARGET omp POST_BUILD
     COMMAND ${CMAKE_COMMAND} -E create_symlink ${LIBOMP_LIB_FILE}
-      libgomp${CMAKE_SHARED_LIBRARY_SUFFIX}
+      libgomp${LIBOMP_LIBRARY_SUFFIX}
     COMMAND ${CMAKE_COMMAND} -E create_symlink ${LIBOMP_LIB_FILE}
-      libiomp5${CMAKE_SHARED_LIBRARY_SUFFIX}
+      libiomp5${LIBOMP_LIBRARY_SUFFIX}
     WORKING_DIRECTORY ${LIBOMP_LIBRARY_DIR}
   )
 endif()
@@ -285,17 +287,19 @@ if(WIN32)
   set(LIBOMP_ALIASES "libiomp5md")
   foreach(alias IN LISTS LIBOMP_ALIASES)
     install(CODE "execute_process(COMMAND \"\${CMAKE_COMMAND}\" -E copy \"${LIBOMP_LIB_FILE}\"
-      \"${alias}${CMAKE_SHARED_LIBRARY_SUFFIX}\" WORKING_DIRECTORY \${CMAKE_INSTALL_PREFIX}/bin)")
+      \"${alias}${LIBOMP_LIBRARY_SUFFIX}\" WORKING_DIRECTORY \${CMAKE_INSTALL_PREFIX}/bin)")
     install(CODE "execute_process(COMMAND \"\${CMAKE_COMMAND}\" -E copy \"${LIBOMP_IMP_LIB_FILE}\"
-      \"${alias}${CMAKE_STATIC_LIBRARY_SUFFIX}\" WORKING_DIRECTORY \${CMAKE_INSTALL_PREFIX}/lib${LIBOMP_LIBDIR_SUFFIX})")
+      \"${alias}${LIBOMP_LIBRARY_SUFFIX}\" WORKING_DIRECTORY \${CMAKE_INSTALL_PREFIX}/lib${LIBOMP_LIBDIR_SUFFIX})")
   endforeach()
 else()
-  install(TARGETS omp LIBRARY DESTINATION lib${LIBOMP_LIBDIR_SUFFIX})
+
+  install(TARGETS omp ${LIBOMP_INSTALL_KIND} DESTINATION lib${LIBOMP_LIBDIR_SUFFIX})
+
   # Create aliases (symlinks) of the library for backwards compatibility
   set(LIBOMP_ALIASES "libgomp;libiomp5")
   foreach(alias IN LISTS LIBOMP_ALIASES)
     install(CODE "execute_process(COMMAND \"\${CMAKE_COMMAND}\" -E create_symlink \"${LIBOMP_LIB_FILE}\"
-      \"${alias}${CMAKE_SHARED_LIBRARY_SUFFIX}\" WORKING_DIRECTORY
+      \"${alias}${LIBOMP_LIBRARY_SUFFIX}\" WORKING_DIRECTORY
       \$ENV{DESTDIR}\${CMAKE_INSTALL_PREFIX}/lib${LIBOMP_LIBDIR_SUFFIX})")
   endforeach()
 endif()