[nvptx] Apply vector-partitionable routines workaround to default vl

Make "[nvptx] Force vl32 if calling vector-partitionable routines" work as well
if vector length is set by modifying PTX_DEFAULT_VECTOR_LENGTH.

2019-01-12  Tom de Vries  <tdevries@suse.de>

	* config/nvptx/nvptx.c (nvptx_goacc_validate_dims_1): In offloading
	region calling vector-partitionable routine, set default_vector_length
	to WARP_SIZE.

From-SVN: r267879

gcc/ChangeLog

 2019-01-12  Tom de Vries  <tdevries@suse.de>
 
+	* config/nvptx/nvptx.c (nvptx_goacc_validate_dims_1): In offloading
+	region calling vector-partitionable routine, set default_vector_length
+	to WARP_SIZE.
+
+2019-01-12  Tom de Vries  <tdevries@suse.de>
+
 	* config/nvptx/nvptx.c (nvptx_goacc_validate_dims_1): Add an use new
 	variable default_vector_length.
 

gcc/config/nvptx/nvptx.c

@@ -5669,6 +5669,8 @@ nvptx_goacc_validate_dims_1 (tree decl, int dims[], int fn_level, unsigned used)
   const char *vector_reason = NULL;
   if (offload_region_p && has_vector_partitionable_routine_calls_p (decl))
     {
+      default_vector_length = PTX_WARP_SIZE;
+
       if (dims[GOMP_DIM_VECTOR] > PTX_WARP_SIZE)
 	{
 	  vector_reason = G_("using vector_length (%d) due to call to"