tree-ssa-loop-ivopts : Add live analysis in regs used in decision making.
Add live anaysis in regs used calculation in decision making of
selecting ivopts candidates.
2023-11-08 Ajit Kumar Agarwal <aagar...@linux.ibm.com>
gcc/ChangeLog:
* tree-ssa-loop-ivopts.cc (get_regs_used): New function.
(determine_set_costs): Call to get_regs_used to use live
analysis.
---
gcc/tree-ssa-loop-ivopts.cc | 73 +++++++++++++++++++++++++++++++++++--
1 file changed, 70 insertions(+), 3 deletions(-)
diff --git a/gcc/tree-ssa-loop-ivopts.cc b/gcc/tree-ssa-loop-ivopts.cc
index c3336603778..e02fe7d434b 100644
--- a/gcc/tree-ssa-loop-ivopts.cc
+++ b/gcc/tree-ssa-loop-ivopts.cc
@@ -6160,6 +6160,68 @@ ivopts_estimate_reg_pressure (struct ivopts_data *data,
unsigned n_invs,
return cost + n_cands;
}
+/* Return regs used based on live-in and liveout of given ssa variables. */
+static unsigned
+get_regs_used (tree ssa_name)
+{
+ unsigned regs_used = 0;
+ gimple *stmt;
+ use_operand_p use;
+ basic_block def_bb = NULL;
+ imm_use_iterator imm_iter;
+
+ stmt = SSA_NAME_DEF_STMT (ssa_name);
+ if (stmt)
+ {
+ def_bb = gimple_bb (stmt);
+ /* Mark defs in liveout bitmap temporarily. */
+ if (def_bb)
+ regs_used++;
+ }
+ else
+ def_bb = ENTRY_BLOCK_PTR_FOR_FN (cfun);
+
+ /* An undefined local variable does not need to be very alive. */
+ if (virtual_operand_p (ssa_name)
+ || ssa_undefined_value_p (ssa_name, false))
+ return 0;
+
+ /* Visit each use of SSA_NAME and if it isn't in the same block as the def,
+ add it to the list of live on entry blocks. */
+ FOR_EACH_IMM_USE_FAST (use, imm_iter, ssa_name)
+ {
+ gimple *use_stmt = USE_STMT (use);
+ basic_block add_block = NULL;
+
+ if (gimple_code (use_stmt) == GIMPLE_PHI)
+ {
+ /* Uses in PHI's are considered to be live at exit of the SRC block
+ as this is where a copy would be inserted. Check to see if it is
+ defined in that block, or whether its live on entry. */
+ int index = PHI_ARG_INDEX_FROM_USE (use);
+ edge e = gimple_phi_arg_edge (as_a <gphi *> (use_stmt), index);
+ if (e->src != def_bb)
+ add_block = e->src;
+ }
+ else if (is_gimple_debug (use_stmt))
+ continue;
+ else
+ {
+ /* If its not defined in this block, its live on entry. */
+ basic_block use_bb = gimple_bb (use_stmt);
+ if (use_bb != def_bb)
+ add_block = use_bb;
+ }
+
+ /* If there was a live on entry use, increment register used. */
+ if (add_block)
+ {
+ regs_used++;
+ }
+ }
+ return regs_used;
+}
+
/* For each size of the induction variable set determine the penalty. */
static void
@@ -6200,15 +6262,20 @@ determine_set_costs (struct ivopts_data *data)
n++;
}
+ unsigned max = 0;
EXECUTE_IF_SET_IN_BITMAP (data->relevant, 0, j, bi)
{
struct version_info *info = ver_info (data, j);
-
if (info->inv_id && info->has_nonlin_use)
- n++;
+ {
+ tree ssa_name = ssa_name (j);
+ n = get_regs_used (ssa_name);
+ if (n >= max)
+ max = n;
+ }
}
- data->regs_used = n;
+ data->regs_used = max;
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, " regs_used %d\n", n);
--
2.39.3
