opal: add a destructor/fini function to opal

This commit is related to an RFC from June 2014. Disscussion can be
found at:

http://www.open-mpi.org/community/lists/devel/2014/07/15140.php

The finalize function is set using either the linker option -fini or
__attribute__((destructor)) depending on compiler support. I have
confirmed that this hybrid approach works with all the major
compilers. The attribute is supported by gcc, clang, llvm, xlc, and
icc. The fini function will support pgi. If a compiler/linker
combination does not support either the destructor or fini function a
message will be printed on re-init indicating it is not supported (an
improvement over the current behavior-- SEGV).

I moved the following to the destructor function:

 - Class system finalize. This solves a bug when MPI_T_finalize is
   called before MPI_Init. The only downside to this change is we will
   leave the footprint of the opal class system after
   MPI_Finalize. This footprint should be relatively small.

This is an alternative to #517 but the two PRs are not
mutually-exclusive (with some modifications). This commit should also
be safe for 1.8.x as it does not change internal or external ABI (#517
changes internal ABI).

Signed-off-by: Nathan Hjelm <hjelmn@lanl.gov>

config/opal_check_attributes.m4

@@ -608,4 +608,5 @@ AC_DEFUN([OPAL_CHECK_ATTRIBUTES], [
                      [Whether your compiler has __attribute__ weak alias or not])
   AC_DEFINE_UNQUOTED(OPAL_HAVE_ATTRIBUTE_DESTRUCTOR, [$opal_cv___attribute__destructor],
                      [Whether your compiler has __attribute__ destructor or not])
+  AM_CONDITIONAL(HAVE_ATTRIBUTE_DESTRUCTOR, [test x$opal_cv___attribute__destructor = x1])
 ])

configure.ac

@@ -799,6 +799,20 @@ m4_ifdef([project_ompi], [OMPI_FIND_MPI_AINT_COUNT_OFFSET])
 # checkpoint results
 AC_CACHE_SAVE
 
+##################################
+# Linker characteristics
+##################################
+
+AC_MSG_CHECKING([the linker for support for the -fini option])
+LDFLAGS_save=$LDFLAGS
+LDFLAGS="$LDFLAGS_save -Wl,-fini -Wl,finalize"
+AC_TRY_LINK([void finalize (void) {}], [], [AC_MSG_RESULT([yes])
+            opal_ld_fini=1], [AC_MSG_RESULT([no])
+            opal_ld_fini=0])
+AM_CONDITIONAL(HAVE_LD_FINI, [test x$opal_ld_fini = x1])
+AC_DEFINE_UNQUOTED(OPAL_HAVE_LD_FINI, [$opal_ld_fini],
+                   [Whether linker has support for the -fini option])
+LDFLAGS=$LDFLAGS_save
 
 ##################################
 # Libraries

opal/Makefile.am

@@ -53,8 +53,19 @@ lib@OPAL_LIB_PREFIX@open_pal_la_LIBADD = \
         util/libopalutil.la \
 	$(MCA_opal_FRAMEWORK_LIBS)
 lib@OPAL_LIB_PREFIX@open_pal_la_DEPENDENCIES = $(lib@OPAL_LIB_PREFIX@open_pal_la_LIBADD)
+
+if HAVE_ATTRIBUTE_DESTRUCTOR
+
 lib@OPAL_LIB_PREFIX@open_pal_la_LDFLAGS = -version-info $(libopen_pal_so_version)
 
+else
+if HAVE_LD_FINI
+
+lib@OPAL_LIB_PREFIX@open_pal_la_LDFLAGS = -version-info $(libopen_pal_so_version) -Wl,-fini,opal_cleanup
+
+endif
+endif
+
 # included subdirectory Makefile.am's and appended-to variables
 headers =
 noinst_LTLIBRARIES =

opal/runtime/opal_finalize.c

@@ -57,6 +57,18 @@
 
 extern int opal_initialized;
 extern int opal_util_initialized;
+extern bool opal_init_called;
+
+static void __opal_attribute_destructor__ opal_cleanup (void)
+{
+    if (!opal_initialized) {
+        /* nothing to do */
+        return;
+    }
+
+    /* finalize the class/object system */
+    opal_class_finalize();
+}
 
 int
 opal_finalize_util(void)
@@ -101,8 +113,9 @@ opal_finalize_util(void)
 
     opal_datatype_finalize();
 
-    /* finalize the class/object system */
-    opal_class_finalize();
+#if !(OPAL_HAVE_LD_FINI || OPAL_HAVE_ATTRIBUTE_DESTRUCTOR)
+    opal_cleanup ();
+#endif
 
     free (opal_process_info.nodename);
     opal_process_info.nodename = NULL;

opal/runtime/opal_init.c

@@ -74,6 +74,7 @@
 const char opal_version_string[] = OPAL_IDENT_STRING;
 
 int opal_initialized = 0;
+bool opal_init_called = false;
 int opal_util_initialized = 0;
 /* We have to put a guess in here in case hwloc is not available.  If
    hwloc is available, this value will be overwritten when the
@@ -266,6 +267,18 @@ opal_init_util(int* pargc, char*** pargv)
         return OPAL_SUCCESS;
     }
 
+#if !(OPAL_HAVE_LD_FINI || OPAL_HAVE_ATTRIBUTE_DESTRUCTOR)
+    if (opal_init_called) {
+        /* can't use show_help here */
+        fprintf (stderr, "opal_init_util: attempted to initialize after finalize without compiler "
+                 "support for either __attribute__(destructor) or linker support for -fini -- process "
+                 "will likely abort\n");
+        return OPAL_ERR_NOT_SUPPORTED;
+    }
+#endif
+
+    opal_init_called = true;
+
     /* set the nodename right away so anyone who needs it has it. Note
      * that we don't bother with fqdn and prefix issues here - we let
      * the RTE later replace this with a modified name if the user