Add missing conversion in vect_create_epilog_for_reduction

The direct_slp_reduc code in vect_create_epilog_for_reduction was
still assuming that all types involved in a reduction are the same
(up to types_compatible_p), whereas we now support differences in
sign.  This was causing an ICE in gcc.dg/vect/pr92324-4.c for SVE.

2019-12-10  Richard Sandiford  <richard.sandiford@arm.com>

gcc/
	* tree-vect-loop.c (vect_create_epilog_for_reduction): When
	handling direct_slp_reduc, allow the PHI arguments to have
	a different type from the vector elements.

From-SVN: r279164

gcc/ChangeLog

 2019-12-10  Richard Sandiford  <richard.sandiford@arm.com>
 
+	* tree-vect-loop.c (vect_create_epilog_for_reduction): When
+	handling direct_slp_reduc, allow the PHI arguments to have
+	a different type from the vector elements.
+
+2019-12-10  Richard Sandiford  <richard.sandiford@arm.com>
+
 	* tree-vect-stmts.c (vectorizable_condition): Record the loop
 	masks required for extract-last reductions.
 

gcc/tree-vect-loop.c

@@ -5054,6 +5054,8 @@ vect_create_epilog_for_reduction (stmt_vec_info stmt_info,
 	      tree scalar_value
 		= PHI_ARG_DEF_FROM_EDGE (orig_phis[i]->stmt,
 					 loop_preheader_edge (loop));
+	      scalar_value = gimple_convert (&seq, TREE_TYPE (vectype),
+					     scalar_value);
 	      vector_identity = gimple_build_vector_from_val (&seq, vectype,
 							      scalar_value);
 	    }