XL: Look for CreateExportList only on AIX

This tool comes with XL on AIX but not on Linux.  Move the
infrastructure to find and use it to the AIX-specific modules.

1 files changed, 22 insertions, 0 deletions

diff --git a/Modules/Platform/AIX-XL.cmake b/Modules/Platform/AIX-XL.cmake
index b3078ff..06a806b 100644
--- a/Modules/Platform/AIX-XL.cmake
+++ b/Modules/Platform/AIX-XL.cmake
@@ -25,4 +25,26 @@ macro(__aix_compiler_xl lang)
   set(CMAKE_SHARED_MODULE_${lang}_FLAGS  " ")
 
   set(CMAKE_${lang}_LINK_FLAGS "-Wl,-bnoipath")
+
+  # Find the CreateExportList program that comes with this toolchain.
+  find_program(CMAKE_XL_CreateExportList
+    NAMES CreateExportList
+    DOC "IBM XL CreateExportList tool"
+    )
+
+  # CMAKE_XL_CreateExportList is part of the AIX XL compilers but not the linux ones.
+  # If we found the tool, we'll use it to create exports, otherwise stick with the regular
+  # create shared library compile line.
+  if (CMAKE_XL_CreateExportList)
+    # The compiler front-end passes all object files, archive files, and shared
+    # library files named on the command line to CreateExportList to create a
+    # list of all symbols to be exported from the shared library.  This causes
+    # all archive members to be copied into the shared library whether they are
+    # needed or not.  Instead we run the tool ourselves to pass only the object
+    # files so that we export only the symbols actually provided by the sources.
+    set(CMAKE_${lang}_CREATE_SHARED_LIBRARY
+      "${CMAKE_XL_CreateExportList} <OBJECT_DIR>/objects.exp <OBJECTS>"
+      "<CMAKE_${lang}_COMPILER> <CMAKE_SHARED_LIBRARY_${lang}_FLAGS> -Wl,-bE:<OBJECT_DIR>/objects.exp <LANGUAGE_COMPILE_FLAGS> <LINK_FLAGS> <CMAKE_SHARED_LIBRARY_CREATE_${lang}_FLAGS> <SONAME_FLAG><TARGET_SONAME> -o <TARGET> <OBJECTS> <LINK_LIBRARIES>"
+      )
+  endif()
 endmacro()