[PATCH] tree-optimization/102847 - properly cost VMAT_INVARIANT loads

[Richard Biener]

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.

Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed.

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.
---
 gcc/tree-vect-stmts.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/gcc/tree-vect-stmts.c b/gcc/tree-vect-stmts.c
index 9cbc1af4cc9..8f527452bd0 100644
--- 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,
-- 
2.31.1