[Bug target/83008] [performance] Is it better to avoid extra instructions in data passing between loops?

[sergey.shalnov at intel dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83008

--- Comment #18 from sergey.shalnov at intel dot com ---
Yes, I agree that vector_store stage has it’s own vectorization cost.
And each vector_store has vector_construction stage. These stages are different
in gcc slp (as you know).
To better illustrate my point of view I would like to propose a patch.
I didn’t submit the patch to community yet because I think it is better to
discuss it before that.

index 0ca42b4..72e3123 100644
--- a/gcc/tree-vect-slp.c
+++ b/gcc/tree-vect-slp.c
@@ -1825,7 +1825,7 @@ vect_analyze_slp_cost_1 (slp_instance instance, slp_tree
node,
            record_stmt_cost (prologue_cost_vec, 1, vector_load,
                              stmt_info, 0, vect_prologue);
          else if (dt == vect_external_def)
-           record_stmt_cost (prologue_cost_vec, 1, vec_construct,
+           record_stmt_cost (prologue_cost_vec, ncopies_for_cost,
vec_construct,
                              stmt_info, 0, vect_prologue);
        }
     }