-/* Condition for breaking the recursion. */
-static bool is_outermost_Start(ir_node *n) {
- /* Test whether this is the outermost Start node. If so
- recursion must end. */
- if ((get_irn_op(n) == op_Block) &&
- (get_Block_n_cfgpreds(n) == 1) &&
- (get_irn_op(skip_Proj(get_Block_cfgpred(n, 0))) == op_Start) &&
- (get_nodes_Block(skip_Proj(get_Block_cfgpred(n, 0))) == n)) {
- return true;
- }
-#if 0
- /* @@@ Bad condition:
- not possible in interprocedural view as outermost_graph is
- not necessarily the only with a dead-end start block.
- Besides current_ir_graph is not set properly. */
- if ((get_irn_op(n) == op_Block) &&
- (n == get_irg_start_block(current_ir_graph))) {
- if ((!interprocedural_view) ||
- (current_ir_graph == outermost_ir_graph))
- return true;
- }
-#endif
- return false;
-}
-
-/* Don't walk from nodes to blocks except for Control flow operations. */
-static INLINE int
-get_start_index(ir_node *n) {
- if (is_cfop(n) || is_fragile_op(n) || get_irn_op(n) == op_Start)
- return -1;
- else
- return 0;
-}
-
-/* Returns current_ir_graph and set it to the irg of predecessor index
- of node n. */
-static INLINE ir_graph *
-switch_irg (ir_node *n, int index) {
- ir_graph *old_current = current_ir_graph;
-
- if (interprocedural_view) {
- /* Only Filter and Block nodes can have predecessors in other graphs. */
- if (get_irn_op(n) == op_Filter)
- n = get_nodes_Block(n);
- if (get_irn_op(n) == op_Block) {
- ir_node *cfop = skip_Proj(get_Block_cfgpred(n, index));
- if (is_ip_cfop(cfop)) {
- current_ir_graph = get_irn_irg(cfop);
- set_irg_visited(current_ir_graph, get_max_irg_visited());
- }
- }
- }
-
- return old_current;
-}
-
-/* Walks up the stack passing n and then finding the node
- where we walked into the irg n is contained in.
- Here we switch the irg. */
-static ir_graph *
-find_irg_on_stack (ir_node *n) {
- ir_node *m;
- ir_graph *old_current = current_ir_graph;
- int i;
-
- if (interprocedural_view) {
- for (i = tos; i >= 0; i--) {
- if (stack[i] == n) break;
- }
- if (i < 0) i = tos;
-
- //printf(" Here\n");
-
- assert (i >= 0);
- for (; i >= 0; i--) {
- m = stack[i];
- //printf(" Visiting %d ", i); DDMN(m);
- if (is_ip_cfop(m)) {
- current_ir_graph = get_irn_irg(m);
- break;
- }
- if (get_irn_op(m) == op_Filter) {
- /* Find the corresponding ip_cfop */
- ir_node *pred = stack[i+1];
- int j;
- for (j = 0; j < get_Filter_n_cg_preds(m); j++)
- if (get_Filter_cg_pred(m, j) == pred) break;
- if (j >= get_Filter_n_cg_preds(m))
- /* It is a filter we didn't pass as the predecessors are marked. */
- continue;
- assert(get_Filter_cg_pred(m, j) == pred);
- switch_irg(m, j);
- break;
- }
- }
- }
-
- return old_current;
-}
-
-static void test(ir_node *pred, ir_node *root, ir_node *this) {
- int i;
- if (get_irn_uplink(pred) >= get_irn_uplink(root)) return;
-
- printf("this: %d ", get_irn_uplink(this)); DDMN(this);
- printf("pred: %d ", get_irn_uplink(pred)); DDMN(pred);
- printf("root: %d ", get_irn_uplink(root)); DDMN(root);
-
- printf("tos: %d\n", tos);
-
- for (i = tos; i >= 0; i--) {
- ir_node *n = stack[i];
- if (!n) continue;
- printf(" uplink: %d, pos: %d ", get_irn_uplink(n), i); DDMN(n);
- }
-}
-
-/* Returns true if n is a loop header, i.e., it is a Block, Phi
- or Filter node and has predecessors within the loop and out
- of the loop. */
-static bool
-is_head (ir_node *n, ir_node *root)
-{
- int i;
- int some_outof_loop = 0, some_in_loop = 0;
-
- /* Test for legal loop header */
- if (!((get_irn_op(n) == op_Block) ||
- (get_irn_op(n) == op_Phi) ||
- ((get_irn_op(n) == op_Filter) && interprocedural_view)))
- return false;
-
- if (!is_outermost_Start(n)) {
- for (i = get_start_index(n); i < get_irn_arity(n); i++) {
- ir_node *pred = get_irn_n(n, i);
- assert(pred);
- if (is_backedge(n, i)) continue;
- if (!irn_is_in_stack(pred)) {
- some_outof_loop = 1;
- } else {
- assert(get_irn_uplink(pred) >= get_irn_uplink(root));
- some_in_loop = 1;
- }
- }
- }
- return some_outof_loop && some_in_loop;
-}
-
-/* Returns index of the predecessor with the smallest dfn number
- greater-equal than limit. */
-static int
-smallest_dfn_pred (ir_node *n, int limit)
-{
- int i, index = -2, min = -1;
-
- if (!is_outermost_Start(n)) {
- for (i = get_start_index(n); i < get_irn_arity(n); i++) {
- ir_node *pred = get_irn_n(n, i);
- assert(pred);
- if (is_backedge(n, i) || !irn_is_in_stack(pred)) continue;
- if (get_irn_dfn(pred) >= limit
- && (min == -1 || get_irn_dfn(pred) < min)) {
- index = i;
- min = get_irn_dfn(pred);
- }
- }
- }
- return index;
-}
-
-/* Returns index of the predecessor with the largest dfn number. */
-static int
-largest_dfn_pred (ir_node *n)
-{
- int i, index = -2, max = -1;
-
- if (!is_outermost_Start(n)) {
- for (i = get_start_index(n); i < get_irn_arity(n); i++) {
- ir_node *pred = get_irn_n(n, i);
- if (is_backedge (n, i) || !irn_is_in_stack(pred)) continue;
- if (get_irn_dfn(pred) > max) {
- index = i;
- max = get_irn_dfn(pred);
- }
- }
- }
- return index;
-}
-
-/* Searches the stack for possible loop heads. Tests these for backedges.
- If it finds a head with an unmarked backedge it marks this edge and
- returns the tail of the loop.
- If it finds no backedge returns NULL. */
-static ir_node *
-find_tail (ir_node *n) {
- ir_node *m;
- int i, res_index = -2;
-
- /*
- if (!icfg && rm_cyclic_phis && remove_cyclic_phis (n)) return NULL;
- */
-
- m = stack[tos-1];
- if (is_head (m, n)) {
- res_index = smallest_dfn_pred(m, 0);
- if ((res_index == -2) && /* no smallest dfn pred found. */
- (n == m))
- return NULL;
- } else {
- if (m == n) return NULL;
- for (i = tos-2; ; --i) {
- m = stack[i];
- if (is_head (m, n)) {
- res_index = smallest_dfn_pred (m, get_irn_dfn(m) + 1);
- if (res_index == -2) /* no smallest dfn pred found. */
- res_index = largest_dfn_pred (m);
- break;
- }
- }
- }
- assert (res_index > -2);
-
- set_backedge (m, res_index);
- return is_outermost_Start(n) ? NULL : get_irn_n(m, res_index);
-}
-
-
-/* The core algorithm. *****************************************/
-
-static void scc (ir_node *n) {
- int i;
- ir_graph *rem;
-
- if (irn_visited(n)) return;
- mark_irn_visited(n);
- //printf("mark: %d ", get_irn_visited(n)); DDMN(n);
- //DDME(get_irg_ent(current_ir_graph));
-
- /* Initialize the node */
- set_irn_dfn(n, current_dfn); /* Depth first number for this node */
- set_irn_uplink(n, current_dfn); /* ... is default uplink. */
- set_irn_loop_tmp(n, NULL);
- current_dfn ++;
-
- /* What's this good for?
- n->ana.scc.section = NULL;
- */
-
- push(n);
-
- if (!is_outermost_Start(n)) {
- for (i = get_start_index(n); i < get_irn_arity(n); i++) {
- ir_node *m;
- if (is_backedge(n, i)) continue;
-
- m = get_irn_n(n, i); //get_irn_ip_pred(n, i);
- if ((!m) || (get_irn_op(m) == op_Unknown)) continue;
- scc (m);
- //return_recur(n, i);
-
- if (irn_is_in_stack(m)) {
- /* Uplink of m is smaller if n->m is a backedge.
- Propagate the uplink to mark the loop. */
- if (get_irn_uplink(m) < get_irn_uplink(n))
- set_irn_uplink(n, get_irn_uplink(m));
- }
- }
- }
- if (get_irn_dfn(n) == get_irn_uplink(n)) {
- /* This condition holds for the node with the incoming backedge. */
- ir_node *tail = find_tail(n);
- if (tail) {
- /* We found a new loop! */
- ir_loop *l = new_loop();
- /* Remove the loop from the stack ... */
- pop_scc_unmark_visit (n);
- /* and recompute it in a better order; and so that it goes into
- the new loop. */
- rem = find_irg_on_stack(tail);
- scc (tail);
- current_ir_graph = rem;
-
- assert (irn_visited(n));
-
- current_loop = l;
- } else {
- pop_scc_to_loop(n);
- }
- }