[RS6000] Make -msingle-pic-base remove the ELFv2 global entry code

For other ABIs, -msingle-pic-base makes gcc omit loading of the PIC
register in function prologues.  This patch makes the option affect
ELFv2 too.

	* config/rs6000/rs6000.c (rs6000_emit_prologue): Don't set
	r2_setup_needed when TARGET_SINGLE_PIC_BASE.
	(rs6000_output_mi_thunk): Likewise.

From-SVN: r228309

gcc/ChangeLog

+2015-10-01  Alan Modra  <amodra@gmail.com>
+
+	* config/rs6000/rs6000.c (rs6000_emit_prologue): Don't set
+	r2_setup_needed when TARGET_SINGLE_PIC_BASE.
+	(rs6000_output_mi_thunk): Likewise.
+
 2015-09-30  Nathan Sidwell  <nathan@codesourcery.com>
 
 	* config/nvptx/mkoffload.c (process): Change offload data format.

gcc/config/rs6000/rs6000.c

@@ -24118,13 +24118,13 @@ rs6000_emit_prologue (void)
 #define NOT_INUSE(R) do {} while (0)
 #endif
 
-  if (DEFAULT_ABI == ABI_ELFv2)
+  if (DEFAULT_ABI == ABI_ELFv2
+      && !TARGET_SINGLE_PIC_BASE)
     {
       cfun->machine->r2_setup_needed = df_regs_ever_live_p (TOC_REGNUM);
 
       /* With -mminimal-toc we may generate an extra use of r2 below.  */
-      if (!TARGET_SINGLE_PIC_BASE
-	  && TARGET_TOC && TARGET_MINIMAL_TOC && get_pool_size () != 0)
+      if (TARGET_TOC && TARGET_MINIMAL_TOC && get_pool_size () != 0)
 	cfun->machine->r2_setup_needed = true;
     }
 
@@ -26800,7 +26800,8 @@ rs6000_output_mi_thunk (FILE *file, tree thunk_fndecl ATTRIBUTE_UNUSED,
   /* Ensure we have a global entry point for the thunk.   ??? We could
      avoid that if the target routine doesn't need a global entry point,
      but we do not know whether this is the case at this point.  */
-  if (DEFAULT_ABI == ABI_ELFv2)
+  if (DEFAULT_ABI == ABI_ELFv2
+      && !TARGET_SINGLE_PIC_BASE)
     cfun->machine->r2_setup_needed = true;
 
   /* Run just enough of rest_of_compilation to get the insns emitted.