re PR rtl-optimization/51051 (build fails on cris-elf building libstdc++-v3)

	PR rtl-optimization/51051
	PR bootstrap/51086
	* function.c (thread_prologue_and_epilogue_insns): Guard
	emitting return with single_succ_p test.

From-SVN: r181391

gcc/ChangeLog

+2011-11-16  Alan Modra  <amodra@gmail.com>
+
+	PR rtl-optimization/51051
+	PR bootstrap/51086
+	* function.c (thread_prologue_and_epilogue_insns): Guard
+	emitting return with single_succ_p test.
+
 2011-11-15  Joern Rennecke  <joern.rennecke@embecosm.com>
 
 	* config/epiphany/epiphany.md (mov<mode>cc): Fix code to

gcc/function.c

@@ -6230,7 +6230,8 @@ thread_prologue_and_epilogue_insns (void)
 	      && !active_insn_between (BB_HEAD (last_bb), BB_END (last_bb)))
 	    convert_jumps_to_returns (last_bb, false, NULL);
 
-	  if (EDGE_COUNT (exit_fallthru_edge->src->preds) != 0)
+	  if (EDGE_COUNT (last_bb->preds) != 0
+	      && single_succ_p (last_bb))
 	    {
 	      last_bb = emit_return_for_exit (exit_fallthru_edge, false);
 	      epilogue_end = returnjump = BB_END (last_bb);