/*
- * Project: libFIRM
- * File name: ir/ana/irscc.c
- * Purpose: Compute the strongly connected regions and build
- * backedge/cfloop datastructures.
- * A variation on the Tarjan algorithm. See also [Trapp:99],
- * Chapter 5.2.1.2.
- * Author: Goetz Lindenmaier
- * Modified by:
- * Created: 7.2002
- * CVS-ID: $Id$
- * Copyright: (c) 2002-2003 Universität Karlsruhe
- * Licence: This file protected by GPL - GNU GENERAL PUBLIC LICENSE.
+ * This file is part of libFirm.
+ * Copyright (C) 2012 University of Karlsruhe.
*/
-#ifdef HAVE_CONFIG_H
+/**
+ * @file
+ * @brief Compute the strongly connected regions and build backedge/cfloop
+ * datastructures. A variation on the Tarjan algorithm. See also
+ * [Trapp:99], Chapter 5.2.1.2.
+ * @author Goetz Lindenmaier
+ * @date 7.2002
+ */
#include "config.h"
-#endif
#include <string.h>
#include "irgwalk.h"
#include "irprog_t.h"
#include "irdump.h"
-
-static ir_graph *outermost_ir_graph; /* The outermost graph the scc is computed
- for */
-static ir_loop *current_loop; /* Current cfloop construction is working
- on. */
-static int loop_node_cnt = 0; /* Counts the number of allocated cfloop nodes.
- Each cfloop node gets a unique number.
- What for? ev. remove. @@@ */
-static int current_dfn = 1; /* Counter to generate depth first numbering
- of visited nodes. */
-
-void link_to_reg_end (ir_node *n, void *env);
-
-/**********************************************************************/
-/* Node attributes **/
-/**********************************************************************/
+#include "ircons_t.h"
+
+/** The outermost graph the scc is computed for */
+static ir_graph *outermost_ir_graph;
+/** Current cfloop construction is working on. */
+static ir_loop *current_loop;
+/** Counts the number of allocated cfloop nodes.
+ * Each cfloop node gets a unique number.
+ * @todo What for? ev. remove.
+ */
+static int loop_node_cnt = 0;
+/** Counter to generate depth first numbering of visited nodes. */
+static int current_dfn = 1;
/**********************************************************************/
/* Node attributes needed for the construction. **/
/**********************************************************************/
+/**
+ * The SCC info. Additional fields for an ir-node needed for the
+ * construction.
+ */
typedef struct scc_info {
- bool in_stack; /* Marks whether node is on the stack. */
- int dfn; /* Depth first search number. */
- int uplink; /* dfn number of ancestor. */
+ int in_stack; /**< Marks whether node is on the stack. */
+ int dfn; /**< Depth first search number. */
+ int uplink; /**< dfn number of ancestor. */
} scc_info;
-static INLINE scc_info* new_scc_info(void) {
- scc_info *info = obstack_alloc (outermost_ir_graph->obst, sizeof (scc_info));
- memset (info, 0, sizeof (scc_info));
- return info;
+/** Allocate a new scc_info on the given obstack */
+static inline scc_info *new_scc_info(struct obstack *obst)
+{
+ return OALLOCZ(obst, scc_info);
}
-static INLINE void
-mark_irn_in_stack (ir_node *n) {
- assert(get_irn_link(n));
- ((scc_info *)n->link)->in_stack = true;
+/**
+ * Marks the node n to be on the stack.
+ */
+static inline void mark_irn_in_stack(ir_node *n)
+{
+ scc_info *info = (scc_info*) get_irn_link(n);
+ info->in_stack = 1;
}
-static INLINE void
-mark_irn_not_in_stack (ir_node *n) {
- assert(get_irn_link(n));
- ((scc_info *)n->link)->in_stack = false;
+/**
+ * Marks the node n to be not on the stack.
+ */
+static inline void mark_irn_not_in_stack(ir_node *n)
+{
+ scc_info *info = (scc_info*) get_irn_link(n);
+ info->in_stack = 0;
}
-static INLINE bool
-irn_is_in_stack (ir_node *n) {
- assert(get_irn_link(n));
- return ((scc_info *)n->link)->in_stack;
+/**
+ * Returns whether node n is on the stack.
+ */
+static inline int irn_is_in_stack(ir_node *n)
+{
+ scc_info *info = (scc_info*) get_irn_link(n);
+ return info->in_stack;
}
-static INLINE void
-set_irn_uplink (ir_node *n, int uplink) {
- assert(get_irn_link(n));
- ((scc_info *)n->link)->uplink = uplink;
+/**
+ * Sets node n uplink value.
+ */
+static inline void set_irn_uplink(ir_node *n, int uplink)
+{
+ scc_info *info = (scc_info*) get_irn_link(n);
+ info->uplink = uplink;
}
-static INLINE int
-get_irn_uplink (ir_node *n) {
- assert(get_irn_link(n));
- return ((scc_info *)n->link)->uplink;
+/**
+ * Return node n uplink value.
+ */
+static inline int get_irn_uplink(ir_node *n)
+{
+ scc_info *info = (scc_info*) get_irn_link(n);
+ return info->uplink;
}
-static INLINE void
-set_irn_dfn (ir_node *n, int dfn) {
- assert(get_irn_link(n));
- ((scc_info *)n->link)->dfn = dfn;
+/**
+ * Sets node n dfn value.
+ */
+static inline void set_irn_dfn(ir_node *n, int dfn)
+{
+ scc_info *info = (scc_info*) get_irn_link(n);
+ info->dfn = dfn;
}
-static INLINE int
-get_irn_dfn (ir_node *n) {
- assert(get_irn_link(n));
- return ((scc_info *)n->link)->dfn;
+/**
+ * Returns node n dfn value.
+ */
+static inline int get_irn_dfn(ir_node *n)
+{
+ scc_info *info = (scc_info*) get_irn_link(n);
+ return info->dfn;
}
/**********************************************************************/
/* A stack. **/
/**********************************************************************/
+/** An IR-node stack */
static ir_node **stack = NULL;
-static int tos = 0; /* top of stack */
-
-static INLINE void init_stack(void) {
- if (stack) {
- ARR_RESIZE (ir_node *, stack, 1000);
- } else {
- stack = NEW_ARR_F (ir_node *, 1000);
- }
- tos = 0;
+/** The top (index) of the IR-node stack */
+static size_t tos = 0;
+
+/**
+ * Initializes the IR-node stack
+ */
+static inline void init_stack(void)
+{
+ if (stack) {
+ ARR_RESIZE(ir_node *, stack, 1000);
+ } else {
+ stack = NEW_ARR_F(ir_node *, 1000);
+ }
+ tos = 0;
}
+static void finish_stack(void)
+{
+ DEL_ARR_F(stack);
+ stack = NULL;
+}
-static INLINE void
-push (ir_node *n)
+/**
+ * Push a node n onto the IR-node stack.
+ */
+static inline void push(ir_node *n)
{
- if (tos == ARR_LEN (stack)) {
- int nlen = ARR_LEN (stack) * 2;
- ARR_RESIZE (ir_node *, stack, nlen);
- }
- stack [tos++] = n;
- mark_irn_in_stack(n);
+ if (tos == ARR_LEN(stack)) {
+ size_t nlen = ARR_LEN(stack) * 2;
+ ARR_RESIZE(ir_node *, stack, nlen);
+ }
+ stack[tos++] = n;
+ mark_irn_in_stack(n);
}
-static INLINE ir_node *
-pop (void)
+/**
+ * Pop a node from the IR-node stack and return it.
+ */
+static inline ir_node *pop(void)
{
- ir_node *n = stack[--tos];
- mark_irn_not_in_stack(n);
- return n;
+ ir_node *n = stack[--tos];
+ mark_irn_not_in_stack(n);
+ return n;
}
-/* The nodes up to n belong to the current loop.
- Removes them from the stack and adds them to the current loop. */
-static INLINE void
-pop_scc_to_loop (ir_node *n)
+/**
+ * The nodes from tos up to n belong to the current loop.
+ * Removes them from the stack and adds them to the current loop.
+ */
+static inline void pop_scc_to_loop(ir_node *n)
{
- ir_node *m;
-
- /*for (;;) {*/
- do {
- m = pop();
- loop_node_cnt++;
- set_irn_dfn(m, loop_node_cnt);
- add_loop_node(current_loop, m);
- set_irn_loop(m, current_loop);
- /* if (m==n) break;*/
- } while(m != n);
+ ir_node *m;
+
+ do {
+ m = pop();
+ loop_node_cnt++;
+ set_irn_dfn(m, loop_node_cnt);
+ add_loop_node(current_loop, m);
+ set_irn_loop(m, current_loop);
+ } while (m != n);
}
/* GL ??? my last son is my grandson??? Removes cfloops with no
ir_nodes in them. Such loops have only another loop as son. (Why
can't they have two loops as sons? Does it never get that far? ) */
-static void close_loop (ir_loop *l)
+static void close_loop(ir_loop *l)
{
- int last = get_loop_n_elements(l) - 1;
- loop_element lelement = get_loop_element(l, last);
- ir_loop *last_son = lelement.son;
-
- if (get_kind(last_son) == k_ir_loop &&
- get_loop_n_elements(last_son) == 1) {
- ir_loop *gson;
-
- lelement = get_loop_element(last_son, 0);
- gson = lelement.son;
- if(get_kind(gson) == k_ir_loop) {
- loop_element new_last_son;
-
- gson -> outer_loop = l;
- new_last_son.son = gson;
- l -> children[last] = new_last_son;
- }
- }
-
- current_loop = l;
+ size_t last = get_loop_n_elements(l) - 1;
+ loop_element lelement = get_loop_element(l, last);
+ ir_loop *last_son = lelement.son;
+
+ if (get_kind(last_son) == k_ir_loop &&
+ get_loop_n_elements(last_son) == 1) {
+ ir_loop *gson;
+
+ lelement = get_loop_element(last_son, 0);
+ gson = lelement.son;
+ if (get_kind(gson) == k_ir_loop) {
+ loop_element new_last_son;
+
+ gson->outer_loop = l;
+ new_last_son.son = gson;
+ l->children[last] = new_last_son;
+
+ /* the loop last_son is dead now, recover at least some memory */
+ DEL_ARR_F(last_son->children);
+ }
+ }
+
+ current_loop = l;
}
-/* Removes and unmarks all nodes up to n from the stack.
- The nodes must be visited once more to assign them to a scc. */
-static INLINE void
-pop_scc_unmark_visit (ir_node *n)
+/**
+ * Removes and unmarks all nodes up to n from the stack.
+ * The nodes must be visited once more to assign them to a scc.
+ */
+static inline void pop_scc_unmark_visit(ir_node *n)
{
- ir_node *m = NULL;
+ ir_node *m;
- while (m != n) {
- m = pop();
- set_irn_visited(m, 0);
- }
+ do {
+ m = pop();
+ set_irn_visited(m, 0);
+ } while (m != n);
}
/**********************************************************************/
/* The loop datastructure. **/
/**********************************************************************/
-/* Allocates a new loop as son of current_loop. Sets current_loop
- to the new loop and returns the father. */
-static ir_loop *new_loop (void) {
- ir_loop *father, *son;
-
- father = current_loop;
-
- son = (ir_loop *) obstack_alloc (outermost_ir_graph->obst, sizeof (ir_loop));
- memset (son, 0, sizeof (ir_loop));
- son->kind = k_ir_loop;
- son->children = NEW_ARR_F (loop_element, 0);
- son->n_nodes = 0;
- son->n_sons=0;
- if (father) {
- son->outer_loop = father;
- add_loop_son(father, son);
- son->depth = father->depth+1;
- } else { /* The root loop */
- son->outer_loop = son;
- son->depth = 0;
- }
-
-#ifdef DEBUG_libfirm
- son->loop_nr = get_irp_new_node_nr();
- son->link = NULL;
-#endif
-
- current_loop = son;
- return father;
+/**
+ * Allocates a new loop as son of current_loop. Sets current_loop
+ * to the new loop and returns its father.
+ * The loop is allocated on the outermost_ir_graphs's obstack.
+ */
+static ir_loop *new_loop(void)
+{
+ ir_loop *father = current_loop;
+ ir_loop *son = alloc_loop(father, get_irg_obstack(outermost_ir_graph));
+
+ current_loop = son;
+ return father;
}
/**********************************************************************/
/* Initialization steps. **********************************************/
-static INLINE void
-init_node (ir_node *n, void *env) {
- if (is_Block(n))
- set_irn_link (n, new_scc_info());
- clear_backedges(n);
-}
-
-static INLINE void
-init_scc_common (void) {
- current_dfn = 1;
- loop_node_cnt = 0;
- init_stack();
+/**
+ * Allocates a scc_info for every Block node n.
+ * Clear the backedges for all nodes.
+ * Called from a walker.
+ */
+static inline void init_node(ir_node *n, void *env)
+{
+ struct obstack *obst = (struct obstack*) env;
+ if (is_Block(n))
+ set_irn_link(n, new_scc_info(obst));
+ clear_backedges(n);
}
-static INLINE void
-init_scc (ir_graph *irg) {
- init_scc_common();
- irg_walk_graph (irg, init_node, NULL, NULL);
+/**
+ * Initializes the common global settings for the scc algorithm
+ */
+static inline void init_scc_common(void)
+{
+ current_dfn = 1;
+ loop_node_cnt = 0;
+ init_stack();
}
-static INLINE void
-init_ip_scc (void) {
- init_scc_common();
- cg_walk (init_node, NULL, NULL);
-
-#if EXPERIMENTAL_CFLOOP_TREE
- cg_walk (link_to_reg_end, NULL, NULL);
-#endif
+/**
+ * Initializes the scc algorithm for the intraprocedural case.
+ * Add scc info to every block node.
+ */
+static inline void init_scc(ir_graph *irg, struct obstack *obst)
+{
+ init_scc_common();
+ irg_walk_graph(irg, init_node, NULL, obst);
}
-/* Condition for breaking the recursion. */
-static bool is_outermost_StartBlock(ir_node *n) {
- /* Test whether this is the outermost Start node. If so
- recursion must end. */
- assert(is_Block(n));
- if ((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;
- }
- return false;
+static inline void finish_scc(void)
+{
+ finish_stack();
}
-/** Returns true if n is a loop header, i.e., it is a Block node
+/** Returns non-zero if n is a loop header, i.e., it is a Block node
* and has predecessors within the cfloop and out of the cfloop.
*
- * @param root: only needed for assertion.
+ * @param n the block node to check
+ * @param root only needed for assertion.
*/
-static bool
-is_head (ir_node *n, ir_node *root)
+static int is_head(ir_node *n, ir_node *root)
{
- int i, arity;
- int some_outof_loop = 0, some_in_loop = 0;
-
- assert(is_Block(n));
-
- if (!is_outermost_StartBlock(n)) {
- arity = get_irn_arity(n);
- for (i = 0; i < arity; i++) {
- ir_node *pred = get_nodes_block(skip_Proj(get_irn_n(n, i)));
- if (is_backedge(n, i)) continue;
- if (!irn_is_in_stack(pred)) {
- some_outof_loop = 1;
- } else {
- if (get_irn_uplink(pred) < get_irn_uplink(root)) {
- DDMN(pred); DDMN(root);
- assert(get_irn_uplink(pred) >= get_irn_uplink(root));
+ int some_outof_loop = 0, some_in_loop = 0;
+ (void) root;
+
+ int const arity = get_Block_n_cfgpreds(n);
+ for (int i = 0; i < arity; i++) {
+ ir_node *pred = get_Block_cfgpred_block(n, i);
+ /* ignore Bad control flow: it cannot happen */
+ if (is_Bad(pred))
+ continue;
+ 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;
+ }
}
- some_in_loop = 1;
- }
- }
- }
- return some_outof_loop && some_in_loop;
+ 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)
+
+/**
+ * Returns non-zero if n is possible loop head of an endless loop.
+ * I.e., it is a Block node and has only predecessors
+ * within the loop.
+ *
+ * @param n the block node to check
+ * @param root only needed for assertion.
+ */
+static int is_endless_head(ir_node *n, ir_node *root)
{
- int i, index = -2, min = -1;
-
- if (!is_outermost_StartBlock(n)) {
- int arity = get_irn_arity(n);
- for (i = 0; i < arity; i++) {
- ir_node *pred = get_nodes_block(skip_Proj(get_irn_n(n, i)));
- 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;
+ int none_outof_loop = 1, some_in_loop = 0;
+ (void) root;
+
+ /* Test for legal loop header: Block, Phi, ... */
+ int const arity = get_Block_n_cfgpreds(n);
+ for (int i = 0; i < arity; i++) {
+ ir_node *pred = get_Block_cfgpred_block(n, i);
+ /* ignore Bad control flow: it cannot happen */
+ if (is_Bad(pred))
+ continue;
+ if (is_backedge(n, i))
+ continue;
+ if (!irn_is_in_stack(pred)) {
+ none_outof_loop = 0;
+ } else {
+ assert(get_irn_uplink(pred) >= get_irn_uplink(root));
+ some_in_loop = 1;
+ }
+ }
+ return none_outof_loop && some_in_loop;
}
-/* Returns index of the predecessor with the largest dfn number. */
-static int
-largest_dfn_pred (ir_node *n)
+/**
+ * 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, max = -1;
-
- if (!is_outermost_StartBlock(n)) {
- int arity = get_irn_arity(n);
- for (i = 0; i < arity; i++) {
- ir_node *pred = get_nodes_block(skip_Proj(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;
+ int i, index = -2, min = -1;
+
+ int arity = get_Block_n_cfgpreds(n);
+ for (i = 0; i < arity; i++) {
+ ir_node *pred = get_Block_cfgpred_block(n, i);
+ /* ignore Bad control flow: it cannot happen */
+ if (is_Bad(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;
}
-/* 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.
- ("disable_backedge" in fiasco) */
-static ir_node *
-find_tail (ir_node *n) {
- ir_node *m;
- int i, res_index = -2;
-
- m = stack[tos-1]; /* tos = top of stack */
- 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_StartBlock(n) ? NULL : get_nodes_block(skip_Proj(get_irn_n(m, res_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;
+
+ int arity = get_Block_n_cfgpreds(n);
+ for (i = 0; i < arity; i++) {
+ ir_node *pred = get_Block_cfgpred_block(n, i);
+ /* ignore Bad control flow: it cannot happen */
+ if (is_Bad(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);
+ }
+ }
+ return index;
}
-/*-----------------------------------------------------------*
- * The core algorithm. *
- *-----------------------------------------------------------*/
-
+/**
+ * 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 res_index = -2;
+ size_t i;
+
+ m = stack[tos - 1]; /* tos = top of stack */
+ 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 - 1; i != 0;) {
+ 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);
+
+ if ((m == n) && (res_index == -2)) {
+ i = (size_t)-1;
+ }
+ break;
+ }
+
+
+ /* We should not walk past our selves on the stack: The upcoming nodes
+ are not in this loop. We assume a loop not reachable from Start. */
+ if (m == n) {
+ i = (size_t)-1;
+ break;
+ }
+ }
+
+ if (i == (size_t)-1) {
+ /* A dead loop not reachable from Start. */
+ for (i = tos - 1; i != 0;) {
+ m = stack[--i];
+ 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;
+ }
+ if (m == n) break; /* It's not an unreachable loop, either. */
+ }
+ //assert(0 && "no head found on stack");
+ }
+ }
+ assert(res_index > -2);
-static void cfscc (ir_node *n) {
- int i;
-
- assert(is_Block(n));
-
- 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 ++;
- push(n);
-
- /* AS: get_start_index might return -1 for Control Flow Nodes, and thus a negative
- array index would be passed to is_backedge(). But CFG Nodes dont't have a backedge array,
- so is_backedge does not access array[-1] but correctly returns false! */
-
- if (!is_outermost_StartBlock(n)) {
- int arity = get_irn_arity(n);
-
- for (i = 0; i < arity; i++) {
- ir_node *m;
- if (is_backedge(n, i)) continue;
- m = get_nodes_block(skip_Proj(get_irn_n(n, i)));
-
- cfscc (m);
- if (irn_is_in_stack(m)) {
- /* Uplink of m is smaller if n->m is a backedge.
- Propagate the uplink to mark the cfloop. */
- 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
- 1) the node with the incoming backedge.
- That is: We found a cfloop!
- 2) Straight line code, because no uplink has been propagated, so the
- uplink still is the same as the dfn.
-
- But n might not be a proper cfloop head for the analysis. Proper cfloop
- heads are Block and Phi nodes. find_tail searches the stack for
- Block's and Phi's and takes those nodes as cfloop heads for the current
- cfloop instead and marks the incoming edge as backedge. */
-
- ir_node *tail = find_tail(n);
- if (tail) {
- /* We have a cfloop, that is no straight line code,
- because we found a cfloop head!
- Next actions: Open a new cfloop on the cfloop tree and
- try to find inner cfloops */
-
-
-#define NO_CFLOOPS_WITHOUT_HEAD 1
-#if NO_CFLOOPS_WITHOUT_HEAD
-
- /* This is an adaption of the algorithm from fiasco / optscc to
- * avoid cfloops without Block or Phi as first node. This should
- * severely reduce the number of evaluations of nodes to detect
- * a fixpoint in the heap analysis.
- * Further it avoids cfloops without firm nodes that cause errors
- * in the heap analyses. */
-
- ir_loop *l;
- int close;
- if (get_loop_n_elements(current_loop) > 0) {
- l = new_loop();
- close = 1;
- } else {
- l = current_loop;
- close = 0;
- }
-
-#else
-
- ir_loop *l = new_loop();
-
-#endif
-
- /* Remove the cfloop from the stack ... */
- pop_scc_unmark_visit (n);
-
- /* The current backedge has been marked, that is temporarily eliminated,
- by find tail. Start the scc algorithm
- anew on the subgraph thats left (the current cfloop without the backedge)
- in order to find more inner cfloops. */
-
- cfscc (tail);
-
- assert (irn_visited(n));
-#if NO_CFLOOPS_WITHOUT_HEAD
- if (close)
-#endif
- close_loop(l);
- }
- else
- {
- /* AS: No cfloop head was found, that is we have straightline code.
- Pop all nodes from the stack to the current cfloop. */
- pop_scc_to_loop(n);
- }
- }
+ set_backedge(m, res_index);
+ return get_Block_cfgpred_block(m, res_index);
}
-/* Constructs backedge information for irg. */
-void construct_cf_backedges(ir_graph *irg) {
- ir_graph *rem = current_ir_graph;
- ir_loop *head_rem;
- ir_node *end = get_irg_end(irg);
- int i;
-
- assert(!interprocedural_view &&
- "use construct_ip_backedges");
-
- current_ir_graph = irg;
- outermost_ir_graph = irg;
-
- init_scc(current_ir_graph);
-
- current_loop = NULL;
- new_loop(); /* sets current_loop */
- head_rem = current_loop; /* Just for assertion */
-
- inc_irg_visited(current_ir_graph);
-
- cfscc(get_irg_end_block(current_ir_graph));
- for (i = 0; i < get_End_n_keepalives(end); i++) {
- ir_node *el = get_End_keepalive(end, i);
- if (is_Block(el)) cfscc(el);
- }
-
- assert(head_rem == current_loop);
- set_irg_loop(current_ir_graph, current_loop);
- set_irg_loopinfo_state(current_ir_graph, loopinfo_cf_consistent);
- assert(get_irg_loop(current_ir_graph)->kind == k_ir_loop);
-
- current_ir_graph = rem;
+/**
+ * returns non.zero if l is the outermost loop.
+ */
+inline static int is_outermost_loop(ir_loop *l)
+{
+ return l == get_loop_outer_loop(l);
}
+/*-----------------------------------------------------------*
+ * The core algorithm. *
+ *-----------------------------------------------------------*/
-void construct_ip_cf_backedges (void) {
- ir_graph *rem = current_ir_graph;
- int rem_ipv = interprocedural_view;
- int i;
-
- assert(get_irp_ip_view_state() == ip_view_valid);
-
- outermost_ir_graph = get_irp_main_irg();
-
- init_ip_scc();
-
- current_loop = NULL;
- new_loop(); /* sets current_loop */
- interprocedural_view = 1;
-
- inc_max_irg_visited();
- for (i = 0; i < get_irp_n_irgs(); i++)
- set_irg_visited(get_irp_irg(i), get_max_irg_visited());
-
- /** We have to start the walk at the same nodes as cg_walk. **/
- /* Walk starting at unreachable procedures. Only these
- * have End blocks visible in interprocedural view. */
- for (i = 0; i < get_irp_n_irgs(); i++) {
- ir_node *sb;
- current_ir_graph = get_irp_irg(i);
-
- sb = get_irg_start_block(current_ir_graph);
-
- if ((get_Block_n_cfgpreds(sb) > 1) ||
- (get_nodes_block(get_Block_cfgpred(sb, 0)) != sb)) continue;
-
- cfscc(get_irg_end_block(current_ir_graph));
- }
-
- /* Check whether we walked all procedures: there could be procedures
- with cyclic calls but no call from the outside. */
- for (i = 0; i < get_irp_n_irgs(); i++) {
- ir_node *sb;
- current_ir_graph = get_irp_irg(i);
-
- /* Test start block: if inner procedure end and end block are not
- * visible and therefore not marked. */
- sb = get_irg_start_block(current_ir_graph);
- if (get_irn_visited(sb) < get_irg_visited(current_ir_graph)) cfscc(sb);
- }
+/**
+ * Walks over all blocks of a graph
+ */
+static void cfscc(ir_node *n)
+{
+ int arity;
+ int i;
+
+ assert(is_Block(n));
+
+ if (irn_visited_else_mark(n)) return;
+
+ /* 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;
+ push(n);
+
+ arity = get_Block_n_cfgpreds(n);
+
+ for (i = 0; i < arity; i++) {
+ ir_node *m;
+
+ if (is_backedge(n, i))
+ continue;
+ m = get_Block_cfgpred_block(n, i);
+ /* ignore Bad control flow: it cannot happen */
+ if (is_Bad(m))
+ continue;
+
+ cfscc(m);
+ if (irn_is_in_stack(m)) {
+ /* Uplink of m is smaller if n->m is a backedge.
+ Propagate the uplink to mark the cfloop. */
+ if (get_irn_uplink(m) < get_irn_uplink(n))
+ set_irn_uplink(n, get_irn_uplink(m));
+ }
+ }
- /* Walk all endless cfloops in inner procedures.
- * We recognize an inner procedure if the End node is not visited. */
- for (i = 0; i < get_irp_n_irgs(); i++) {
- ir_node *e;
- current_ir_graph = get_irp_irg(i);
+ if (get_irn_dfn(n) == get_irn_uplink(n)) {
+ /* This condition holds for
+ 1) the node with the incoming backedge.
+ That is: We found a cfloop!
+ 2) Straight line code, because no uplink has been propagated, so the
+ uplink still is the same as the dfn.
+
+ But n might not be a proper cfloop head for the analysis. Proper cfloop
+ heads are Block and Phi nodes. find_tail searches the stack for
+ Block's and Phi's and takes those nodes as cfloop heads for the current
+ cfloop instead and marks the incoming edge as backedge. */
+
+ ir_node *tail = find_tail(n);
+ if (tail) {
+ /* We have a cfloop, that is no straight line code,
+ because we found a cfloop head!
+ Next actions: Open a new cfloop on the cfloop tree and
+ try to find inner cfloops */
+
+ /* This is an adaption of the algorithm from fiasco / optscc to
+ * avoid cfloops without Block or Phi as first node. This should
+ * severely reduce the number of evaluations of nodes to detect
+ * a fixpoint in the heap analysis.
+ * Further it avoids cfloops without firm nodes that cause errors
+ * in the heap analyses. */
+
+ ir_loop *l;
+ int close;
+ if ((get_loop_n_elements(current_loop) > 0) || (is_outermost_loop(current_loop))) {
+ l = new_loop();
+ close = 1;
+ } else {
+ l = current_loop;
+ close = 0;
+ }
+
+ /* Remove the cfloop from the stack ... */
+ pop_scc_unmark_visit(n);
+
+ /* The current backedge has been marked, that is temporarily eliminated,
+ by find tail. Start the scc algorithm
+ anew on the subgraph thats left (the current cfloop without the backedge)
+ in order to find more inner cfloops. */
+
+ cfscc(tail);
+
+ assert(irn_visited(n));
+ if (close)
+ close_loop(l);
+ } else {
+ /* AS: No cfloop head was found, that is we have straight line code.
+ Pop all nodes from the stack to the current cfloop. */
+ pop_scc_to_loop(n);
+ }
+ }
+}
- e = get_irg_end(current_ir_graph);
- if (get_irn_visited(e) < get_irg_visited(current_ir_graph)) {
- int j;
- /* Don't visit the End node. */
- for (j = 0; j < get_End_n_keepalives(e); j++) {
- ir_node *el = get_End_keepalive(e, j);
- if (is_Block(el)) cfscc(el);
- }
- }
- }
+void construct_cf_backedges(ir_graph *irg)
+{
+ ir_loop *head_rem;
+ ir_node *end = get_irg_end(irg);
+ struct obstack temp;
+ int i;
- set_irg_loop(outermost_ir_graph, current_loop);
- set_irg_loopinfo_state(current_ir_graph, loopinfo_cf_ip_consistent);
- assert(get_irg_loop(outermost_ir_graph)->kind == k_ir_loop);
+ outermost_ir_graph = irg;
- current_ir_graph = rem;
- interprocedural_view = rem_ipv;
-}
+ obstack_init(&temp);
+ init_scc(irg, &temp);
+ current_loop = NULL;
+ new_loop(); /* sets current_loop */
+ head_rem = current_loop; /* Just for assertion */
-static void reset_backedges(ir_node *n) {
- assert(is_Block(n));
- int rem = interprocedural_view;
- interprocedural_view = 1;
- clear_backedges(n);
- interprocedural_view = 0;
- clear_backedges(n);
- interprocedural_view = rem;
-}
+ inc_irg_visited(irg);
-static void loop_reset_backedges(ir_loop *l) {
- int i;
- reset_backedges(get_loop_node(l, 0));
- for (i = 0; i < get_loop_n_nodes(l); ++i)
- set_irn_loop(get_loop_node(l, i), NULL);
- for (i = 0; i < get_loop_n_sons(l); ++i) {
- loop_reset_backedges(get_loop_son(l, i));
- }
-}
+ /* walk over all blocks of the graph, including keep alives */
+ cfscc(get_irg_end_block(irg));
+ for (i = get_End_n_keepalives(end) - 1; i >= 0; --i) {
+ ir_node *el = get_End_keepalive(end, i);
+ if (is_Block(el))
+ cfscc(el);
+ }
+ finish_scc();
+ obstack_free(&temp, NULL);
-/* Removes all cfloop information.
- Resets all backedges */
-void free_cfloop_information(ir_graph *irg) {
- if (get_irg_loop(irg))
- loop_reset_backedges(get_irg_loop(irg));
- set_irg_loop(irg, NULL);
- set_irg_loopinfo_state(current_ir_graph, loopinfo_none);
- /* We cannot free the cfloop nodes, they are on the obstack. */
+ assert(head_rem == current_loop);
+ mature_loops(current_loop, get_irg_obstack(irg));
+ set_irg_loop(irg, current_loop);
+ add_irg_properties(irg, IR_GRAPH_PROPERTY_CONSISTENT_LOOPINFO);
}
-
-void free_all_cfloop_information (void) {
- int i;
- int rem = interprocedural_view;
- interprocedural_view = 1; /* To visit all filter nodes */
- for (i = 0; i < get_irp_n_irgs(); i++) {
- free_cfloop_information(get_irp_irg(i));
- }
- interprocedural_view = rem;
+void assure_loopinfo(ir_graph *irg)
+{
+ if (irg_has_properties(irg, IR_GRAPH_PROPERTY_CONSISTENT_LOOPINFO))
+ return;
+ construct_cf_backedges(irg);
}
projects / libfirm / blobdiff