Re: [PATCH, committed] Fix TLS and -fstack-protector on sparc64

[Eric Botcazou <ebotcazou at libertysurf dot fr>]

> TLS details in .debug_info (sparc_output_dwarf_dtprel) and
> tgd_add in tg_call's delay slot, that's it AFAIK.
> The latter is that Sun as/ld requires AFAIK only
> R_SPARC_TLS_GD_HI22
> R_SPARC_TLS_GD_LO10
> R_SPARC_TLS_GD_ADD
> R_SPARC_TLS_GD_CALL
> sequence (in that order), while gas handles also
> R_SPARC_TLS_GD_HI22
> R_SPARC_TLS_GD_LO10
> R_SPARC_TLS_GD_CALL
> R_SPARC_TLS_GD_ADD	! in call's delay slot

OK, thanks.  Indeed the page I linked to has a note explicitly forbidding to 
put the 'add' in the delay slot of the 'call'; the problem is that the reorg 
pass nonetheless does so :-(  I've applied the first patch to every branch.

And I've narrowed down the libgomp problem to these lines in configure.tgt:

# Optimize TLS usage by avoiding the overhead of dynamic allocation.
# This does require that the library be present during process 
# startup, so mark the library as not to be dlopened.
if test $have_tls = yes && test "$with_gnu_ld" = "yes"; then
	XCFLAGS="${XCFLAGS} -ftls-model=initial-exec"
	XLDFLAGS="${XLDFLAGS} -Wl,-z,nodlopen"
fi

A bit too Linux-centric I'm afraid. :-)  I'm proposing the second patch.


2006-02-09  Eric Botcazou  <ebotcazou@libertysurf.fr>

gcc/
	* config/sparc/sparc.c (tls_call_delay): Fix oversight.

libgomp/

	* configure.tgt: Force initial-exec TLS model on Linux only.



-- 
Eric Botcazou

Index: configure.tgt
===================================================================
--- configure.tgt	(revision 110691)
+++ configure.tgt	(working copy)
@@ -13,9 +13,14 @@
 # Optimize TLS usage by avoiding the overhead of dynamic allocation.
 # This does require that the library be present during process 
 # startup, so mark the library as not to be dlopened.
-if test $have_tls = yes && test "$with_gnu_ld" = "yes"; then
+if test $have_tls = yes ; then
+  case "${target}" in
+
+    *-*-linux*)
 	XCFLAGS="${XCFLAGS} -ftls-model=initial-exec"
 	XLDFLAGS="${XLDFLAGS} -Wl,-z,nodlopen"
+	;;
+  esac
 fi
 
 # Since we require POSIX threads, assume a POSIX system by default.

Index: config/sparc/sparc.c
===================================================================
--- config/sparc/sparc.c	(revision 110691)
+++ config/sparc/sparc.c	(working copy)
@@ -2415,26 +2415,34 @@ empty_delay_slot (rtx insn)
 int
 tls_call_delay (rtx trial)
 {
-  rtx pat, unspec;
+  rtx pat;
 
   /* Binutils allows
-     call __tls_get_addr, %tgd_call (foo)
-      add %l7, %o0, %o0, %tgd_add (foo)
+       call __tls_get_addr, %tgd_call (foo)
+        add %l7, %o0, %o0, %tgd_add (foo)
      while Sun as/ld does not.  */
   if (TARGET_GNU_TLS || !TARGET_TLS)
     return 1;
 
   pat = PATTERN (trial);
-  if (GET_CODE (pat) != SET || GET_CODE (SET_DEST (pat)) != PLUS)
-    return 1;
 
-  unspec = XEXP (SET_DEST (pat), 1);
-  if (GET_CODE (unspec) != UNSPEC
-      || (XINT (unspec, 1) != UNSPEC_TLSGD
-	  && XINT (unspec, 1) != UNSPEC_TLSLDM))
-    return 1;
+  /* We must reject tgd_add{32|64}, i.e.
+       (set (reg) (plus (reg) (unspec [(reg) (symbol_ref)] UNSPEC_TLSGD)))
+     and tldm_add{32|64}, i.e.
+       (set (reg) (plus (reg) (unspec [(reg) (symbol_ref)] UNSPEC_TLSLDM)))
+     for Sun as/ld.  */
+  if (GET_CODE (pat) == SET
+      && GET_CODE (SET_SRC (pat)) == PLUS)
+    {
+      rtx unspec = XEXP (SET_SRC (pat), 1);
+
+      if (GET_CODE (unspec) == UNSPEC
+	  && (XINT (unspec, 1) == UNSPEC_TLSGD
+	      || XINT (unspec, 1) == UNSPEC_TLSLDM))
+	return 0;
+    }
 
-  return 0;
+  return 1;
 }
 
 /* Return nonzero if TRIAL, an insn, can be combined with a 'restore'