Re: PATCH: Fix invalid loader fixups from shared libobjc with hpux 10.20

["John David Anglin" <dave at hiauly1 dot hia dot nrc dot ca>]

I have revised the patch.  This is for the 3.0 branch.  For the main,
only the last two hunks are applicable.

> Geoff K already checked in a patch right around the first hunk - please
> update your sources and recheck, because part of the code you're
> patching no longer exists.

I reworked Geoff's patch for the branch.  It also resolves the section
problem for the address constant.  Thus, it should be preferred for
the sake of compatibility.

> > I also noted that the class reference labels were output without changing
> > to the readonly data section.  On the HP, they were going into the $CODE$
> > subspace (the text section).
> 
> The second hunk looks OK to me, although just for paranoia's sake it
> would be good to have a Linux build/test (any arch) for the branch.

I also reworked this part.  On inspection of the hppa assembler code,
I noticed that there was no alignment output for __objc_class_name_Object.
I presume for example that __objc_class_name_Object is a handle for
_OBJC_CLASS_NAME_0 and that the addresses should be the same.  The lack
of alignment alignment output for __objc_class_name_Object could cause
the addresses to differ.

The code is now modified to use a declaration for __objc_class_name_Object
to generate the label.  The decl for __objc_class_name_Object has the same
type and therefore alignment as _OBJC_CLASS_NAME_0.  The dont_output_data
mode of assemble_variable is used so that __objc_class_name_Object and
_OBJC_CLASS_NAME_0 are now at the same address.  As a side benefit,
debugging information for the symbol should now be correct although
I haven't checked this.  Setting DECL_INITIAL to error_mark_node is
necessary for it to go in the readonly section when possible.

I have built and checked this change under hppa1.1-hp-hpux10.20 and 
i686-pc-linux-gnu.  No testsuite errors were observed using -static,
-threads (-pthreads), -fPIC or "".  I have also examined the assembler
output from Object.m to see that it looks ok.

This fixes a critical usage problem under hppa1.1-hp-hpux10.20 and I
believe therefore that it should be installed on the branch.

Dave
-- 
J. David Anglin                                  dave.anglin@nrc.ca
National Research Council of Canada              (613) 990-0752 (FAX: 952-6605)

2001-05-31  John David Anglin  <dave@hiauly1.hia.nrc.ca>

	* objc/objc-act.c (handle_class_ref): Use rest_of_decl_compilation
	so that CHOOSE_SECTION gets used.
	(handle_impent): Use assemble_variable to put the global objc class
	and category name labels in the readonly data section.

--- objc-act.c.orig	Tue May  1 19:06:28 2001
+++ objc-act.c	Thu May 31 16:22:28 2001
@@ -8362,19 +8362,16 @@
       pushdecl (decl);
       rest_of_decl_compilation (decl, 0, 0, 0);
 
-      /* Make following constant read-only (why not)?  */
-      readonly_data_section ();
-
+      /* Make a decl for the address.  */
+      sprintf (string, "%sobjc_class_ref_%s",
+	       (flag_next_runtime ? "." : "__"), name);
       exp = build1 (ADDR_EXPR, string_type_node, decl);
+      decl = build_decl (VAR_DECL, get_identifier (string), string_type_node);
+      DECL_INITIAL (decl) = exp;
+      TREE_STATIC (decl) = 1;
 
-      /* Align the section properly.  */
-      assemble_constant_align (exp);
-
-      /* Inform the assembler about this new external thing.  */
-      assemble_external (decl);
-
-      /* Output a constant to reference this address.  */
-      output_constant (exp, int_size_in_bytes (string_type_node));
+      pushdecl (decl);
+      rest_of_decl_compilation (decl, 0, 0, 0);
     }
   else
     {
@@ -8414,10 +8411,19 @@
 
       else
 	{
+	  tree decl;
+
 	  sprintf (string, "%sobjc_class_name_%s",
 		   (flag_next_runtime ? "." : "__"), class_name);
-	  assemble_global (string);
-	  assemble_label (string);
+
+	  decl = build_decl (VAR_DECL, get_identifier (string),
+			     build_array_type (char_type_node, 0));
+	  TREE_PUBLIC (decl) = 1;
+	  TREE_READONLY (decl) = 1;
+	  TREE_CONSTANT (decl) = 1;
+	  DECL_INITIAL (decl) = error_mark_node;
+	
+	  assemble_variable (decl, 1, 0, 1);
 	}
     }
 
@@ -8447,11 +8453,20 @@
 
       else
 	{
+	  tree decl;
+
 	  sprintf (string, "%sobjc_category_name_%s_%s",
 		   (flag_next_runtime ? "." : "__"),
 		   class_name, class_super_name);
-	  assemble_global (string);
-	  assemble_label (string);
+
+	  decl = build_decl (VAR_DECL, get_identifier (string),
+			     build_array_type (char_type_node, 0));
+	  TREE_PUBLIC (decl) = 1;
+	  TREE_READONLY (decl) = 1;
+	  TREE_CONSTANT (decl) = 1;
+	  DECL_INITIAL (decl) = error_mark_node;
+	
+	  assemble_variable (decl, 1, 0, 1);
 	}
     }
 }