tree-optimization/95839 - allow CTOR vectorization without loads

This removes a premature check for enough datarefs in a basic-block
before we consider vectorizing it which leaves basic-blocks with
just vectorizable vector constructors unvectorized.  The check
is effectively done by the following check for store groups
which then also include constructors.

2020-06-25  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/95839
	* tree-vect-slp.c (vect_slp_analyze_bb_1): Remove premature
	check on the number of datarefs.

	* gcc.dg/vect/bb-slp-pr95839.c: New testcase.

diff --git a/gcc/testsuite/gcc.dg/vect/bb-slp-pr95839.c b/gcc/testsuite/gcc.dg/vect/bb-slp-pr95839.c
new file mode 100644 (file)
index 0000000..0bfba01
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/bb-slp-pr95839.c
@@ -0,0 +1,13 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target vect_float } */
+/* { dg-additional-options "-w -Wno-psabi" } */
+
+typedef float __attribute__((vector_size(16))) v4f32;
+
+v4f32 f(v4f32 a, v4f32 b)
+{
+  /* Check that we vectorize this CTOR without any loads.  */
+  return (v4f32){a[0] + b[0], a[1] + b[1], a[2] + b[2], a[3] + b[3]};
+}
+
+/* { dg-final { scan-tree-dump "basic block vectorized" "slp2" } } */

diff --git a/gcc/tree-vect-slp.c b/gcc/tree-vect-slp.c
index 5883ec58c7a540eb8d0df9eeb1b90eebb5d646f5..46a75f1c2072f65d972fa808ba5c1effc60ce830 100644 (file)
--- a/gcc/tree-vect-slp.c
+++ b/gcc/tree-vect-slp.c
@@ -3149,15 +3149,6 @@ vect_slp_analyze_bb_1 (bb_vec_info bb_vinfo, int n_stmts, bool &fatal)
       return false;
     }
 
-  if (BB_VINFO_DATAREFS (bb_vinfo).length () < 2)
-    {
-      if (dump_enabled_p ())
-        dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
-                        "not vectorized: not enough data-refs in "
-                        "basic block.\n");
-      return false;
-    }
-
   if (!vect_analyze_data_ref_accesses (bb_vinfo))
     {
      if (dump_enabled_p ())
@@ -3169,9 +3160,9 @@ vect_slp_analyze_bb_1 (bb_vec_info bb_vinfo, int n_stmts, bool &fatal)
 
   vect_slp_check_for_constructors (bb_vinfo);
 
-  /* If there are no grouped stores in the region there is no need
-     to continue with pattern recog as vect_analyze_slp will fail
-     anyway.  */
+  /* If there are no grouped stores and no constructors in the region
+     there is no need to continue with pattern recog as vect_analyze_slp
+     will fail anyway.  */
   if (bb_vinfo->grouped_stores.is_empty ())
     {
       if (dump_enabled_p ())