}
#endif
-/* Condition for breaking the recursion. */
+/**
+ * Check weather a given node represents the outer most Start
+ * block. In intra-procedural view this is the start block of the
+ * current graph, in interprocedural view it is the start block
+ * of the outer most graph.
+ *
+ * @param n the node to check
+ *
+ * This is the condition for breaking the scc recursion.
+ */
static int 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)) {
+ /* Test whether this is the outermost Start node. */
+ if (is_Block(n) && get_Block_n_cfgpreds(n) == 1) {
+ ir_node *pred = skip_Proj(get_Block_cfgpred(n, 0));
+ if (is_Start(pred) && get_nodes_block(pred) == n)
return 1;
}
-#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 ((!get_interprocedural_view()) ||
- (current_ir_graph == outermost_ir_graph))
- return 1;
- }
-#endif
return 0;
}
#endif
}
-/* Test for legal loop header: Block, Phi, ... */
+/**
+ * Return non-zero if the given node is a legal loop header:
+ * Block, Phi, Filter.
+ *
+ * @param n the node to check
+ */
static INLINE int is_possible_loop_head(ir_node *n) {
ir_op *op = get_irn_op(n);
return ((op == op_Block) ||
* Returns non-zero 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.
- * @param root: only needed for assertion.
+ *
+ * @param n the node to check
+ * @param root only needed for assertion.
*/
static int is_head(ir_node *n, ir_node *root) {
int i, arity;
return 0;
if (!is_outermost_Start(n)) {
+#ifndef NDEBUG
+ int uplink = get_irn_uplink(root);
+#endif
arity = get_irn_arity(n);
for (i = get_start_index(n); i < arity; i++) {
- ir_node *pred = get_irn_n(n, i);
- assert(pred);
+ ir_node *pred;
if (is_backedge(n, i))
continue;
- if (!irn_is_in_stack(pred)) {
+ pred = get_irn_n(n, i);
+ if (! irn_is_in_stack(pred)) {
some_outof_loop = 1;
} else {
- if (get_irn_uplink(pred) < get_irn_uplink(root)) {
- assert(get_irn_uplink(pred) >= get_irn_uplink(root));
- }
+ assert(get_irn_uplink(pred) >= uplink);
some_in_loop = 1;
}
}
}
- return some_outof_loop && some_in_loop;
+ return some_outof_loop & some_in_loop;
}
/**
* Returns non-zero if n is possible loop head of an endless loop.
* I.e., it is a Block, Phi or Filter node and has only predecessors
* within the loop.
- * @param root: only needed for assertion.
+ *
+ * @param n the node to check
+ * @param root only needed for assertion.
*/
static int is_endless_head(ir_node *n, ir_node *root) {
int i, arity;
- int some_outof_loop = 0, some_in_loop = 0;
+ int none_outof_loop = 1, some_in_loop = 0;
/* Test for legal loop header: Block, Phi, ... */
if (!is_possible_loop_head(n))
return 0;
if (!is_outermost_Start(n)) {
+#ifndef NDEBUG
+ int uplink = get_irn_uplink(root);
+#endif
arity = get_irn_arity(n);
for (i = get_start_index(n); i < arity; i++) {
- ir_node *pred = get_irn_n(n, i);
- assert(pred);
- if (is_backedge(n, i)) { continue; }
+ ir_node *pred;
+ if (is_backedge(n, i))
+ continue;
+ pred = get_irn_n(n, i);
if (!irn_is_in_stack(pred)) {
- some_outof_loop = 1; //printf(" some out of loop ");
+ none_outof_loop = 0;
} else {
- if (get_irn_uplink(pred) < get_irn_uplink(root)) {
- assert(get_irn_uplink(pred) >= get_irn_uplink(root));
- }
+ assert(get_irn_uplink(pred) >= uplink);
some_in_loop = 1;
}
}
}
- return !some_outof_loop && some_in_loop;
+ return none_outof_loop & some_in_loop;
}
/** Returns index of the predecessor with the smallest dfn number
int arity = get_irn_arity(n);
for (i = get_start_index(n); i < arity; i++) {
ir_node *pred = get_irn_n(n, i);
- assert(pred);
- if (is_backedge(n, i) || !irn_is_in_stack(pred)) continue;
+ 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. */
+/**
+ * Returns index of the predecessor with the largest dfn number.
+ */
static int largest_dfn_pred(ir_node *n) {
int i, index = -2, max = -1;
int arity = get_irn_arity(n);
for (i = get_start_index(n); i < arity; i++) {
ir_node *pred = get_irn_n(n, i);
- if (is_backedge (n, i) || !irn_is_in_stack(pred)) continue;
+ if (is_backedge (n, i) || !irn_is_in_stack(pred))
+ continue;
if (get_irn_dfn(pred) > max) {
index = i;
max = get_irn_dfn(pred);
* If it finds no backedge returns NULL.
* ("disable_backedge" in fiasco)
*
- * @param n A node where uplink == dfn.
+ * @param n A node where uplink == dfn.
*/
static ir_node *find_tail(ir_node *n) {
ir_node *m;
if (!icfg && rm_cyclic_phis && remove_cyclic_phis (n)) return NULL;
*/
m = stack[tos-1]; /* tos = top of stack */
- if (is_head (m, n)) {
+ if (is_head(m, n)) {
res_index = smallest_dfn_pred(m, 0);
if ((res_index == -2) && /* no smallest dfn pred found. */
(n == m))
for (i = tos-2; i >= 0; --i) {
m = stack[i];
- if (is_head (m, n)) {
- res_index = smallest_dfn_pred (m, get_irn_dfn(m) + 1);
+ 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);
+ res_index = largest_dfn_pred(m);
if ((m == n) && (res_index == -2)) { /* don't walk past loop head. */
i = -1;
i = -1;
break;
}
-
}
if (i < 0) {
/* A dead loop not reachable from Start. */
for (i = tos-2; i >= 0; --i) {
m = stack[i];
- if (is_endless_head (m, n)) {
- res_index = smallest_dfn_pred (m, get_irn_dfn(m) + 1);
+ if (is_endless_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;
be a head. I.e., the code is "dying". We break the loop by
setting Bad nodes. */
int arity = get_irn_arity(n);
+ ir_node *bad = get_irg_bad(get_irn_irg(n));
for (i = -1; i < arity; ++i) {
- set_irn_n(n, i, get_irg_bad(get_irn_irg(n)));
+ set_irn_n(n, i, bad);
}
return NULL;
}
- assert (res_index > -2);
+ assert(res_index > -2);
set_backedge(m, res_index);
return is_outermost_Start(n) ? NULL : get_irn_n(m, res_index);
* The core algorithm. *
*-----------------------------------------------------------*/
+/**
+ * The core algorithm: Find strongly coupled components.
+ *
+ * @param n node to start
+ */
static void scc(ir_node *n) {
- int i;
- if (irn_visited(n)) return;
+ if (irn_visited(n))
+ return;
mark_irn_visited(n);
/* 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(n, NULL);
- current_dfn ++;
+ ++current_dfn;
push(n);
/* AS: get_start_index might return -1 for Control Flow Nodes, and thus a negative
so is_backedge does not access array[-1] but correctly returns false! */
if (!is_outermost_Start(n)) {
- int arity = get_irn_arity(n);
+ int i, arity = get_irn_arity(n);
- for (i = get_start_index(n); i < arity; i++) {
+ for (i = get_start_index(n); i < arity; ++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; */
+ if (is_backedge(n, i))
+ continue;
+ m = get_irn_n(n, i);
scc(m);
if (irn_is_in_stack(m)) {
/* Uplink of m is smaller if n->m is a backedge.
uplink still is the same as the dfn.
But n might not be a proper loop head for the analysis. Proper loop
- heads are Block and Phi nodes. find_tail searches the stack for
+ heads are Block and Phi nodes. find_tail() searches the stack for
Block's and Phi's and takes those nodes as loop heads for the current
loop instead and marks the incoming edge as backedge. */
ir_node *tail = find_tail(n);
- if (tail) {
+ if (tail != NULL) {
/* We have a loop, that is no straight line code,
because we found a loop head!
Next actions: Open a new loop on the loop tree and
/* The current backedge has been marked, that is temporarily eliminated,
by find tail. Start the scc algorithm
- anew on the subgraph that is left (the current loop without the backedge)
+ again on the subgraph that is left (the current loop without the backedge)
in order to find more inner loops. */
scc(tail);
}
}
+#ifdef INTERPROCEDURAL_VIEW
static void my_scc(ir_node *n) {
int i;
if (irn_visited(n))
}
}
}
+#endif /* INTERPROCEDURAL_VIEW */
/* Constructs backedge information for irg. In interprocedural view constructs
backedges for all methods called by irg, too. */