leverage linker relaxation on ppc vxworks RTPs

2018-10-11  Doug Rupp  <rupp@adacore.com>
            Olivier Hainque  <hainque@adacore.com>

        * config/rs6000/vxworks.h (VXWORKS_RELAX_LINK_SPEC): New macro.
        Pass --relax to the linker for RTPs.
        (LINK_SPEC): Append VXWORKS_RELAX_LINK_SPEC.

Co-Authored-By: Olivier Hainque <hainque@adacore.com>

From-SVN: r265054

gcc/ChangeLog

+2018-10-11  Doug Rupp  <rupp@adacore.com>
+            Olivier Hainque  <hainque@adacore.com>
+
+	* config/rs6000/vxworks.h (VXWORKS_RELAX_LINK_SPEC): New macro.
+	Pass --relax to the linker for RTPs.
+	(LINK_SPEC): Append VXWORKS_RELAX_LINK_SPEC.
+
 2018-10-11  Andrew Stubbs  <ams@codesourcery.com>
 	    Jan Hubicka  <jh@suse.cz>
 	    Martin Jambor  <mjambor@suse.cz>

gcc/config/rs6000/vxworks.h

@@ -88,8 +88,15 @@ VXWORKS_ADDITIONAL_CPP_SPEC
 
 #undef  LIB_SPEC
 #define LIB_SPEC VXWORKS_LIB_SPEC
+
+/* For RTPs, leverage linker relaxation.  This helps programs referring
+   to, typically, kernel services too far away for short calls.  This is more
+   precise than -mlongcall and can be overriden with -Wl,--no-relax.  */
+#define VXWORKS_RELAX_LINK_SPEC "%{mrtp:--relax}"
+
 #undef  LINK_SPEC
-#define LINK_SPEC VXWORKS_LINK_SPEC
+#define LINK_SPEC VXWORKS_LINK_SPEC " " VXWORKS_RELAX_LINK_SPEC
+
 #undef  STARTFILE_SPEC
 #define STARTFILE_SPEC VXWORKS_STARTFILE_SPEC
 #undef  ENDFILE_SPEC