rs6000: Fix the new SSP guard configuration code (PR79140)

I foolishly tested this with r241087 reverted.  After that revision
default_stack_protect_guard is no longer called if the compiler defaults
to using the TLS guard, which of course is the wrong thing to do if
there is some other way to enable the global guard.

This fixes it.


	PR target/78875
	PR target/79140
	* config/rs6000/rs6000.c (TARGET_STACK_PROTECT_GUARD): Unconditionally
	define to rs6000_init_stack_protect_guard.
	(rs6000_init_stack_protect_guard): New function.

From-SVN: r244677

gcc/ChangeLog

+2017-01-19  Segher Boessenkool  <segher@kernel.crashing.org>
+
+	PR target/78875
+	PR target/79140
+	* config/rs6000/rs6000.c (TARGET_STACK_PROTECT_GUARD): Unconditionally
+	define to rs6000_init_stack_protect_guard.
+	(rs6000_init_stack_protect_guard): New function.
+
 2017-01-19  Matthew Fortune  <matthew.fortune@imgtec.com>
 	    Yunqiang Su  <yunqiang.su@imgtec.com>
 

gcc/config/rs6000/rs6000.c

@@ -1758,10 +1758,8 @@ static const struct attribute_spec rs6000_attribute_table[] =
 #define TARGET_VECTORIZE_BUILTIN_MD_VECTORIZED_FUNCTION \
   rs6000_builtin_md_vectorized_function
 
-#ifdef TARGET_THREAD_SSP_OFFSET
 #undef TARGET_STACK_PROTECT_GUARD
-#define TARGET_STACK_PROTECT_GUARD hook_tree_void_null
-#endif
+#define TARGET_STACK_PROTECT_GUARD rs6000_init_stack_protect_guard
 
 #if !TARGET_MACHO
 #undef TARGET_STACK_PROTECT_FAIL
@@ -9479,6 +9477,17 @@ rs6000_legitimize_tls_address (rtx addr, enum tls_model model)
   return dest;
 }
 
+/* Only create the global variable for the stack protect guard if we are using
+   the global flavor of that guard.  */
+static tree
+rs6000_init_stack_protect_guard (void)
+{
+  if (rs6000_stack_protector_guard == SSP_GLOBAL)
+    return default_stack_protect_guard ();
+
+  return NULL_TREE;
+}
+
 /* Implement TARGET_CANNOT_FORCE_CONST_MEM.  */
 
 static bool