edge
ssa_redirect_edge (edge e, basic_block dest)
{
tree phi;
tree list = NULL, *last = &list;
tree src, dst, node;
/* Remove the appropriate PHI arguments in E's destination block. */
for (phi = phi_nodes (e->dest); phi; phi = PHI_CHAIN (phi))
{
if (PHI_ARG_DEF (phi, e->dest_idx) == NULL_TREE)
continue;
src = PHI_ARG_DEF (phi, e->dest_idx);
dst = PHI_RESULT (phi);
node = build_tree_list (dst, src);
*last = node;
last = &TREE_CHAIN (node);
}
e = redirect_edge_succ_nodup (e, dest);
PENDING_STMT (e) = list;
return e;
}
static void
tree_ssa_phiopt (void)
{
basic_block bb;
bool removed_phis = false;
/* Search every basic block for PHI nodes we may be able to optimize. */
FOR_EACH_BB (bb)
{
tree arg0, arg1, phi;
/* We're searching for blocks with one PHI node which has two
arguments. */
phi = phi_nodes (bb);
if (phi && PHI_CHAIN (phi) == NULL
&& PHI_NUM_ARGS (phi) == 2)
{
arg0 = PHI_ARG_DEF (phi, 0);
arg1 = PHI_ARG_DEF (phi, 1);
/* Do the replacement of conditional if it can be done. */
if (conditional_replacement (bb, phi, arg0, arg1)
|| value_replacement (bb, phi, arg0, arg1)
|| abs_replacement (bb, phi, arg0, arg1))
{
/* We have done the replacement so we need to rebuild the
cfg when this pass is complete. */
removed_phis = true;
}
}
}
}
static basic_block
find_bb_for_arg (gphi *phi, tree def)
{
size_t i;
bool foundone = false;
basic_block result = NULL;
for (i = 0; i < gimple_phi_num_args (phi); i++)
if (PHI_ARG_DEF (phi, i) == def)
{
if (foundone)
return NULL;
foundone = true;
result = gimple_phi_arg_edge (phi, i)->src;
}
return result;
}
static void
eliminate_build (elim_graph g)
{
tree Ti;
int p0, pi;
gimple_stmt_iterator gsi;
clear_elim_graph (g);
for (gsi = gsi_start_phis (g->e->dest); !gsi_end_p (gsi); gsi_next (&gsi))
{
gimple phi = gsi_stmt (gsi);
source_location locus;
p0 = var_to_partition (g->map, gimple_phi_result (phi));
/* Ignore results which are not in partitions. */
if (p0 == NO_PARTITION)
continue;
Ti = PHI_ARG_DEF (phi, g->e->dest_idx);
locus = gimple_phi_arg_location_from_edge (phi, g->e);
/* If this argument is a constant, or a SSA_NAME which is being
left in SSA form, just queue a copy to be emitted on this
edge. */
if (!phi_ssa_name_p (Ti)
|| (TREE_CODE (Ti) == SSA_NAME
&& var_to_partition (g->map, Ti) == NO_PARTITION))
{
/* Save constant copies until all other copies have been emitted
on this edge. */
VEC_safe_push (int, heap, g->const_dests, p0);
VEC_safe_push (tree, heap, g->const_copies, Ti);
VEC_safe_push (source_location, heap, g->copy_locus, locus);
}
else
{
static unsigned int
rename_ssa_copies (void)
{
var_map map;
basic_block bb;
gimple_stmt_iterator gsi;
tree var, part_var;
gimple stmt, phi;
unsigned x;
FILE *debug;
bool updated = false;
memset (&stats, 0, sizeof (stats));
if (dump_file && (dump_flags & TDF_DETAILS))
debug = dump_file;
else
debug = NULL;
map = init_var_map (num_ssa_names);
FOR_EACH_BB (bb)
{
/* Scan for real copies. */
for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
{
stmt = gsi_stmt (gsi);
if (gimple_assign_ssa_name_copy_p (stmt))
{
tree lhs = gimple_assign_lhs (stmt);
tree rhs = gimple_assign_rhs1 (stmt);
updated |= copy_rename_partition_coalesce (map, lhs, rhs, debug);
}
}
}
FOR_EACH_BB (bb)
{
/* Treat PHI nodes as copies between the result and each argument. */
for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi))
{
size_t i;
tree res;
phi = gsi_stmt (gsi);
res = gimple_phi_result (phi);
/* Do not process virtual SSA_NAMES. */
if (virtual_operand_p (res))
continue;
/* Make sure to only use the same partition for an argument
as the result but never the other way around. */
if (SSA_NAME_VAR (res)
&& !DECL_IGNORED_P (SSA_NAME_VAR (res)))
for (i = 0; i < gimple_phi_num_args (phi); i++)
{
tree arg = PHI_ARG_DEF (phi, i);
if (TREE_CODE (arg) == SSA_NAME)
updated |= copy_rename_partition_coalesce (map, res, arg,
debug);
}
/* Else if all arguments are in the same partition try to merge
it with the result. */
else
{
int all_p_same = -1;
int p = -1;
for (i = 0; i < gimple_phi_num_args (phi); i++)
{
tree arg = PHI_ARG_DEF (phi, i);
if (TREE_CODE (arg) != SSA_NAME)
{
all_p_same = 0;
break;
}
else if (all_p_same == -1)
{
p = partition_find (map->var_partition,
SSA_NAME_VERSION (arg));
all_p_same = 1;
}
else if (all_p_same == 1
&& p != partition_find (map->var_partition,
SSA_NAME_VERSION (arg)))
{
all_p_same = 0;
break;
}
}
if (all_p_same == 1)
updated |= copy_rename_partition_coalesce (map, res,
PHI_ARG_DEF (phi, 0),
debug);
}
}
}
if (debug)
dump_var_map (debug, map);
/* Now one more pass to make all elements of a partition share the same
root variable. */
for (x = 1; x < num_ssa_names; x++)
{
part_var = partition_to_var (map, x);
if (!part_var)
continue;
var = ssa_name (x);
if (SSA_NAME_VAR (var) == SSA_NAME_VAR (part_var))
continue;
if (debug)
{
fprintf (debug, "Coalesced ");
print_generic_expr (debug, var, TDF_SLIM);
fprintf (debug, " to ");
print_generic_expr (debug, part_var, TDF_SLIM);
fprintf (debug, "\n");
}
stats.coalesced++;
replace_ssa_name_symbol (var, SSA_NAME_VAR (part_var));
}
statistics_counter_event (cfun, "copies coalesced",
stats.coalesced);
delete_var_map (map);
return updated ? TODO_remove_unused_locals : 0;
}