tree-optimization/102847 - properly cost VMAT_INVARIANT loads

The following adds proper costing of VMAT_INVARIANT loads, avoiding
to ask the target about the cost of an unsupported vector load cost
which we won't emit anyway.

2021-10-21  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/102847
	* tree-vect-stmts.c (vect_model_load_cost): Explicitely
	handle VMAT_INVARIANT as a splat in the prologue.

diff --git a/gcc/tree-vect-stmts.c b/gcc/tree-vect-stmts.c
index 9cbc1af4cc913d07c32f953986159fecea6942e5..8f527452bd0e37b6df04bc1661b061d3d27dce40 100644 (file)
--- a/gcc/tree-vect-stmts.c
+++ b/gcc/tree-vect-stmts.c
@@ -1191,6 +1191,13 @@ vect_model_load_cost (vec_info *vinfo,
                                       ncopies * assumed_nunits,
                                       scalar_load, stmt_info, 0, vect_body);
     }
+  else if (memory_access_type == VMAT_INVARIANT)
+    {
+      /* Invariant loads will ideally be hoisted and splat to a vector.  */
+      prologue_cost += record_stmt_cost (cost_vec, 1,
+                                        scalar_to_vec, stmt_info, 0,
+                                        vect_prologue);
+    }
   else
     vect_get_load_cost (vinfo, stmt_info, ncopies,
                        alignment_support_scheme, misalignment, first_stmt_p,