[committed] Fix parisc unwind start offset

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

This patch fixes a problem with incorrect ranges in the parisc unwind
data.  When the function symbol is used as the start offset in the unwind
entry, there is a problem with starting offset for weak/overloaded functions.
The fix is to replace the function symbol with a local symbol which reduces
to a section offset.

The problem was noticed in the linux kernel.  The patch was tested on
hppa-unknown-linux-gnu.  Committed to trunk.

Dave
-- 
J. David Anglin                                  dave.anglin@nrc-cnrc.gc.ca
National Research Council of Canada              (613) 990-0752 (FAX: 952-6602)

2009-10-30  John David Anglin  <dave.anglin@nrc-cnrc.gc.ca>

	* config/tc-hppa.c (pa_build_unwind_subspace): Replace start symbol
	with local symbol.

Index: config/tc-hppa.c
===================================================================
RCS file: /cvs/src/src/gas/config/tc-hppa.c,v
retrieving revision 1.145
diff -u -3 -p -r1.145 tc-hppa.c
--- config/tc-hppa.c	24 Jul 2009 11:45:00 -0000	1.145
+++ config/tc-hppa.c	29 Oct 2009 18:37:39 -0000
@@ -5961,13 +5961,41 @@ pa_build_unwind_subspace (struct call_in
   subsegT save_subseg;
   unsigned int unwind;
   int reloc;
-  char *p;
+  char *name, *p;
+  symbolS *symbolP;
 
   if ((bfd_get_section_flags (stdoutput, now_seg)
        & (SEC_ALLOC | SEC_LOAD | SEC_READONLY))
       != (SEC_ALLOC | SEC_LOAD | SEC_READONLY))
     return;
 
+  /* Replace the start symbol with a local symbol that will be reduced
+     to a section offset.  This avoids problems with weak functions with
+     multiple definitions, etc.  */
+  name = xmalloc (strlen ("L$\001start_")
+		  + strlen (S_GET_NAME (call_info->start_symbol))
+		  + 1);
+  strcpy (name, "L$\001start_");
+  strcat (name, S_GET_NAME (call_info->start_symbol));
+
+  /* If we have a .procend preceded by a .exit, then the symbol will have
+     already been defined.  In that case, we don't want another unwind
+     entry.  */
+  symbolP = symbol_find (name);
+  if (symbolP)
+    {
+      xfree (name);
+      return;
+    }
+  else
+    {
+      symbolP = symbol_new (name, now_seg,
+			    S_GET_VALUE (call_info->start_symbol), frag_now);
+      gas_assert (symbolP);
+      S_CLEAR_EXTERNAL (symbolP);
+      symbol_table_insert (symbolP);
+    }
+
   reloc = R_PARISC_SEGREL32;
   save_seg = now_seg;
   save_subseg = now_subseg;
@@ -5993,7 +6021,7 @@ pa_build_unwind_subspace (struct call_in
   /* Relocation info. for start offset of the function.  */
   md_number_to_chars (p, 0, 4);
   fix_new_hppa (frag_now, p - frag_now->fr_literal, 4,
-		call_info->start_symbol, (offsetT) 0,
+		symbolP, (offsetT) 0,
 		(expressionS *) NULL, 0, reloc,
 		e_fsel, 32, 0, 0);