IBM Z: Cover weak symbols with -munaligned-symbols

With the recently introduced -munaligned-symbols option byte-sized
variables which are resolved externally are considered to be
potentially misaligned.
However, this should rather also be applied to symbols which resolve
locally if they are weak. Done with this patch.

gcc/ChangeLog:

	* config/s390/s390.cc (s390_encode_section_info): Replace
	SYMBOL_REF_LOCAL_P with decl_binds_to_current_def_p.

gcc/testsuite/ChangeLog:

	* gcc.target/s390/unaligned-2.c: New test.

gcc/config/s390/s390.cc

@@ -13802,10 +13802,8 @@ s390_encode_section_info (tree decl, rtx rtl, int first)
 	 byte aligned as mandated by our ABI.  This behavior can be
 	 overridden for external symbols with the -munaligned-symbols
 	 switch.  */
-      if (DECL_ALIGN (decl) % 16
-	  && (DECL_USER_ALIGN (decl)
-	      || (!SYMBOL_REF_LOCAL_P (XEXP (rtl, 0))
-		  && s390_unaligned_symbols_p)))
+      if ((DECL_USER_ALIGN (decl) && DECL_ALIGN (decl) % 16)
+	  || (s390_unaligned_symbols_p && !decl_binds_to_current_def_p (decl)))
 	SYMBOL_FLAG_SET_NOTALIGN2 (XEXP (rtl, 0));
       else if (DECL_ALIGN (decl) % 32)
 	SYMBOL_FLAG_SET_NOTALIGN4 (XEXP (rtl, 0));

gcc/testsuite/gcc.target/s390/unaligned-2.c

@@ -0,0 +1,16 @@
+/* weak symbols might get overridden in another module by symbols
+   which are not aligned on a 2-byte boundary.  Although this violates
+   the zABI we try to handle this gracefully by not using larl on
+   these symbols if -munaligned-symbols has been specified.  */
+
+/* { dg-do compile } */
+/* { dg-options "-O3 -march=z900 -fno-section-anchors -munaligned-symbols" } */
+unsigned char __attribute__((weak)) weaksym = 0;
+
+unsigned char
+foo ()
+{
+  return weaksym;
+}
+
+/* { dg-final { scan-assembler-times "larl\t%r\[0-9\]*,weaksym\n" 0 } } */