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Re: Remove magic treatment of toc symbols for powerpc ELF
- From: Alan Modra <amodra at gmail dot com>
- To: binutils at sourceware dot org
- Date: Tue, 25 Mar 2014 12:06:16 +1030
- Subject: Re: Remove magic treatment of toc symbols for powerpc ELF
- Authentication-results: sourceware.org; auth=none
- References: <20140305085953 dot GF26922 at bubble dot grove dot modra dot org>
On Wed, Mar 05, 2014 at 07:29:53PM +1030, Alan Modra wrote:
> The XCOFF assembler does some weird things with instructions like
> `lwz 9,sym(30'. See the comment in md_apply_fix. From an ELF
> perspective, it's weird even to magically select a TOC16 reloc
> when a symbol is in the TOC/GOT. ELF assemblers generally use
> modifiers like @toc to select relocs, so remove this "feature"
> for ELF. I believe this was to support gcc -m32 -mcall-aixdesc
> but that combination of gcc options has been broken for a long
> time.
It turns out that glibc's sysdeps/powerpc/powerpc64/start.S uses this
feature. :-(
* config/tc-ppc.c (ppc_is_toc_sym): Revert 2014-03-05.
(md_assemble): Likewise. Warn.
diff --git a/gas/config/tc-ppc.c b/gas/config/tc-ppc.c
index 8609ce7..9f24f3f 100644
--- a/gas/config/tc-ppc.c
+++ b/gas/config/tc-ppc.c
@@ -2530,16 +2530,25 @@ parse_toc_entry (enum toc_size_qualifier *toc_kind)
}
#endif
-#ifdef OBJ_XCOFF
+#if defined (OBJ_XCOFF) || defined (OBJ_ELF)
/* See whether a symbol is in the TOC section. */
static int
ppc_is_toc_sym (symbolS *sym)
{
+#ifdef OBJ_XCOFF
return (symbol_get_tc (sym)->symbol_class == XMC_TC
|| symbol_get_tc (sym)->symbol_class == XMC_TC0);
-}
#endif
+#ifdef OBJ_ELF
+ const char *sname = segment_name (S_GET_SEGMENT (sym));
+ if (ppc_obj64)
+ return strcmp (sname, ".toc") == 0;
+ else
+ return strcmp (sname, ".got") == 0;
+#endif
+}
+#endif /* defined (OBJ_XCOFF) || defined (OBJ_ELF) */
#ifdef OBJ_ELF
@@ -3167,11 +3176,17 @@ md_assemble (char *str)
&& operand->shift == 0)
{
reloc = BFD_RELOC_16;
-#ifdef OBJ_XCOFF
+#if defined OBJ_XCOFF || defined OBJ_ELF
/* Note: the symbol may be not yet defined. */
if ((operand->flags & PPC_OPERAND_PARENS) != 0
&& ppc_is_toc_sym (ex.X_add_symbol))
- reloc = BFD_RELOC_PPC_TOC16;
+ {
+ reloc = BFD_RELOC_PPC_TOC16;
+#ifdef OBJ_ELF
+ as_warn (_("assuming %s on symbol"),
+ ppc_obj64 ? "@toc" : "@xgot");
+#endif
+ }
#endif
}
--
Alan Modra
Australia Development Lab, IBM