This patch improves the ivopts address cost calculcation for modes
in which an index must be scaled rather than unscaled. Previously
we would only try the scaled form if the unscaled form was valid.
Many of the SVE tests rely on this when matching scaled indices.
Tested on aarch64-linux-gnu, x86_64-linux-gnu and powerpc64-linux-gnu.
OK to install?
Richard
2017-11-03 Richard Sandiford <richard.sandif...@linaro.org>
Alan Hayward <alan.hayw...@arm.com>
David Sherwood <david.sherw...@arm.com>
gcc/
* tree-ssa-loop-ivopts.c (get_address_cost): Try using a
scaled index even if the unscaled address was invalid.
Don't increase the complexity of using a scale in that case.
Index: gcc/tree-ssa-loop-ivopts.c
===================================================================
--- gcc/tree-ssa-loop-ivopts.c 2017-11-03 12:20:07.041206480 +0000
+++ gcc/tree-ssa-loop-ivopts.c 2017-11-03 12:20:07.193201997 +0000
@@ -4333,18 +4333,25 @@ get_address_cost (struct ivopts_data *da
machine_mode addr_mode = TYPE_MODE (type);
machine_mode mem_mode = TYPE_MODE (TREE_TYPE (*use->op_p));
addr_space_t as = TYPE_ADDR_SPACE (TREE_TYPE (use->iv->base));
+ /* Only true if ratio != 1. */
+ bool ok_with_ratio_p = false;
+ bool ok_without_ratio_p = false;
if (!aff_combination_const_p (aff_inv))
{
parts.index = integer_one_node;
/* Addressing mode "base + index". */
- if (valid_mem_ref_p (mem_mode, as, &parts))
+ ok_without_ratio_p = valid_mem_ref_p (mem_mode, as, &parts);
+ if (ratio != 1)
{
parts.step = wide_int_to_tree (type, ratio);
/* Addressing mode "base + index << scale". */
- if (ratio != 1 && !valid_mem_ref_p (mem_mode, as, &parts))
+ ok_with_ratio_p = valid_mem_ref_p (mem_mode, as, &parts);
+ if (!ok_with_ratio_p)
parts.step = NULL_TREE;
-
+ }
+ if (ok_with_ratio_p || ok_without_ratio_p)
+ {
if (maybe_nonzero (aff_inv->offset))
{
parts.offset = wide_int_to_tree (sizetype, aff_inv->offset);
@@ -4444,7 +4451,9 @@ get_address_cost (struct ivopts_data *da
if (parts.symbol != NULL_TREE)
cost.complexity += 1;
- if (parts.step != NULL_TREE && !integer_onep (parts.step))
+ /* Don't increase the complexity of adding a scaled index if it's
+ the only kind of index that the target allows. */
+ if (parts.step != NULL_TREE && ok_without_ratio_p)
cost.complexity += 1;
if (parts.base != NULL_TREE && parts.index != NULL_TREE)
cost.complexity += 1;
