[gcc r11-3481] aix: collect2 visibility

[David Edelsohn]

https://gcc.gnu.org/g:e721d1137fb3f0323d31b767bc64c772086ff868

commit r11-3481-ge721d1137fb3f0323d31b767bc64c772086ff868
Author: David Edelsohn <dje.gcc@gmail.com>
Date:   Wed Sep 23 16:52:15 2020 -0400

    aix: collect2 visibility
    
    The code that collect2 generates, compiles and links into applications
    and shared libraries to initialize constructors and register DWARF tables
    is built with the compiler options used to invoke the linker.  If the
    compiler options change the visibility from default, the library
    initialization routines will not be visible and this can prevent
    initialization.
    
    This patch checks if the command line sets visibiliity and then adds
    GCC pragmas to the initialization code generated by collect2 if
    necessary to define the visibility on global, exported functions as default.
    
    gcc/ChangeLog:
    
    2020-09-26  David Edelsohn  <dje.gcc@gmail.com>
                Clement Chigot  <clement.chigot@atos.com>
    
            * collect2.c (visibility_flag): New.
            (main): Detect -fvisibility.
            (write_c_file_stat): Push and pop default visibility.

Diff:
---
 gcc/collect2.c | 26 +++++++++++++++++++++++++-
 1 file changed, 25 insertions(+), 1 deletion(-)

diff --git a/gcc/collect2.c b/gcc/collect2.c
index f8a5ce45994..6d074a79e91 100644
--- a/gcc/collect2.c
+++ b/gcc/collect2.c
@@ -184,7 +184,8 @@ static int strip_flag;			/* true if -s */
 static int export_flag;                 /* true if -bE */
 static int aix64_flag;			/* true if -b64 */
 static int aixrtl_flag;			/* true if -brtl */
-static int aixlazy_flag;               /* true if -blazy */
+static int aixlazy_flag;		/* true if -blazy */
+static int visibility_flag;		/* true if -fvisibility */
 #endif
 
 enum lto_mode_d {
@@ -1239,6 +1240,11 @@ main (int argc, char **argv)
 	      *c_ptr++ = xstrdup (q);
 	    }
 	}
+#ifdef COLLECT_EXPORT_LIST
+      /* Detect any invocation with -fvisibility.  */
+      if (strncmp (q, "-fvisibility", 12) == 0)
+	visibility_flag = 1;
+#endif
     }
   obstack_free (&temporary_obstack, temporary_firstobj);
   *c_ptr++ = "-fno-profile-arcs";
@@ -2131,6 +2137,11 @@ write_c_file_stat (FILE *stream, const char *name ATTRIBUTE_UNUSED)
       fprintf (stream, "\t}\n");
     }
 
+#ifdef COLLECT_EXPORT_LIST
+  /* Set visibility of initializers to default.  */
+  if (visibility_flag)
+    fprintf (stream, "#pragma GCC visibility push(default)\n");
+#endif
   fprintf (stream, "void %s() {\n", initname);
   if (constructors.number > 0 || frames)
     {
@@ -2163,11 +2174,24 @@ write_c_file_stat (FILE *stream, const char *name ATTRIBUTE_UNUSED)
 	       destructors.number + frames);
     }
   fprintf (stream, "}\n");
+#ifdef COLLECT_EXPORT_LIST
+  if (visibility_flag)
+    fprintf (stream, "#pragma GCC visibility pop\n");
+#endif
 
   if (shared_obj)
     {
+#ifdef COLLECT_EXPORT_LIST
+      /* Set visibility of initializers to default.  */
+      if (visibility_flag)
+	fprintf (stream, "#pragma GCC visibility push(default)\n");
+#endif
       COLLECT_SHARED_INIT_FUNC (stream, initname);
       COLLECT_SHARED_FINI_FUNC (stream, fininame);
+#ifdef COLLECT_EXPORT_LIST
+      if (visibility_flag)
+	fprintf (stream, "#pragma GCC visibility pop\n");
+#endif
     }
 }