Handle exit phi without header phi in create_parallel_loop

2015-07-16  Tom de Vries  <tom@codesourcery.com>

	* tree-parloops.c (create_parallel_loop): Handle case that exit phi does
	not have a corresponding loop header phi.

From-SVN: r225873

gcc/ChangeLog

 2015-07-16  Tom de Vries  <tom@codesourcery.com>
 
+	* tree-parloops.c (create_parallel_loop): Handle case that exit phi does
+	not have a corresponding loop header phi.
+
+2015-07-16  Tom de Vries  <tom@codesourcery.com>
+
 	* tree-parloops.c (create_loads_for_reductions): Handle case that
 	reduction is unused.
 

gcc/tree-parloops.c

@@ -2050,13 +2050,17 @@ create_parallel_loop (struct loop *loop, tree loop_fn, tree data,
        !gsi_end_p (gpi); gsi_next (&gpi))
     {
       source_location locus;
-      tree def;
       gphi *phi = gpi.phi ();
-      gphi *stmt;
+      tree def = PHI_ARG_DEF_FROM_EDGE (phi, exit);
+      gimple def_stmt = SSA_NAME_DEF_STMT (def);
 
-      stmt = as_a <gphi *> (
-	       SSA_NAME_DEF_STMT (PHI_ARG_DEF_FROM_EDGE (phi, exit)));
+      /* If the exit phi is not connected to a header phi in the same loop, this
+	 value is not modified in the loop, and we're done with this phi.  */
+      if (!(gimple_code (def_stmt) == GIMPLE_PHI
+	    && gimple_bb (def_stmt) == loop->header))
+	continue;
 
+      gphi *stmt = as_a <gphi *> (def_stmt);
       def = PHI_ARG_DEF_FROM_EDGE (stmt, loop_preheader_edge (loop));
       locus = gimple_phi_arg_location_from_edge (stmt,
 						 loop_preheader_edge (loop));