On Thu, Nov 21, 2019 at 1:07 PM Richard Sandiford
<richard.sandif...@arm.com> wrote:
>
> gcc.target/aarch64/sve/clastb_[57].c started failing after the increase
> in the cost of vec_to_scalar (r278452). The problem is that we were
> double-counting the cost of the CLASTB: once in vect_model_reduction_cost
> as a vec_to_scalar and once in vectorizable_condition as a plain
> vector_stmt.
>
> Based on the TODO above vect_model_reduction_cost, I think the
> preferred long-term direction is for vectorizable_* to cost these
> things itself, so that's what the patch does (for this one case only).
>
> Tested on aarch64-linux-gnu and x86_64-linux-gnu. OK to install?
OK.
> Richard
>
>
> 2019-11-21 Richard Sandiford <richard.sandif...@arm.com>
>
> gcc/
> * tree-vect-stmts.c (vect_model_simple_cost): Take an optional
> vect_cost_for_stmt.
> (vectorizable_condition): Calculate the cost of EXTRACT_LAST_REDUCTION
> here rather than...
> * tree-vect-loop.c (vect_model_reduction_cost): ...here.
>
> Index: gcc/tree-vect-stmts.c
> ===================================================================
> --- gcc/tree-vect-stmts.c 2019-11-16 10:29:21.211212189 +0000
> +++ gcc/tree-vect-stmts.c 2019-11-21 12:02:44.058240392 +0000
> @@ -860,7 +860,8 @@ vect_model_simple_cost (stmt_vec_info st
> enum vect_def_type *dt,
> int ndts,
> slp_tree node,
> - stmt_vector_for_cost *cost_vec)
> + stmt_vector_for_cost *cost_vec,
> + vect_cost_for_stmt kind = vector_stmt)
> {
> int inside_cost = 0, prologue_cost = 0;
>
> @@ -907,7 +908,7 @@ vect_model_simple_cost (stmt_vec_info st
> }
>
> /* Pass the inside-of-loop statements to the target-specific cost model.
> */
> - inside_cost += record_stmt_cost (cost_vec, ncopies, vector_stmt,
> + inside_cost += record_stmt_cost (cost_vec, ncopies, kind,
> stmt_info, 0, vect_body);
>
> if (dump_enabled_p ())
> @@ -10081,15 +10082,18 @@ vectorizable_condition (stmt_vec_info st
> return false;
> }
> }
> - if (expand_vec_cond_expr_p (vectype, comp_vectype,
> - cond_code))
> - {
> - STMT_VINFO_TYPE (stmt_info) = condition_vec_info_type;
> - vect_model_simple_cost (stmt_info, ncopies, dts, ndts, slp_node,
> - cost_vec);
> - return true;
> - }
> - return false;
> +
> + vect_cost_for_stmt kind = vector_stmt;
> + if (reduction_type == EXTRACT_LAST_REDUCTION)
> + /* Count one reduction-like operation per vector. */
> + kind = vec_to_scalar;
> + else if (!expand_vec_cond_expr_p (vectype, comp_vectype, cond_code))
> + return false;
> +
> + STMT_VINFO_TYPE (stmt_info) = condition_vec_info_type;
> + vect_model_simple_cost (stmt_info, ncopies, dts, ndts, slp_node,
> + cost_vec, kind);
> + return true;
> }
>
> /* Transform. */
> Index: gcc/tree-vect-loop.c
> ===================================================================
> --- gcc/tree-vect-loop.c 2019-11-19 16:25:24.882645490 +0000
> +++ gcc/tree-vect-loop.c 2019-11-21 12:02:44.050240447 +0000
> @@ -3924,8 +3924,11 @@ vect_model_reduction_cost (stmt_vec_info
>
> code = gimple_assign_rhs_code (orig_stmt_info->stmt);
>
> - if (reduction_type == EXTRACT_LAST_REDUCTION
> - || reduction_type == FOLD_LEFT_REDUCTION)
> + if (reduction_type == EXTRACT_LAST_REDUCTION)
> + /* No extra instructions are needed in the prologue. The loop body
> + operations are costed in vectorizable_condition. */
> + inside_cost = 0;
> + else if (reduction_type == FOLD_LEFT_REDUCTION)
> {
> /* No extra instructions needed in the prologue. */
> prologue_cost = 0;
