/*
- * 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.
+ * Copyright (C) 1995-2007 University of Karlsruhe. All right reserved.
+ *
+ * This file is part of libFirm.
+ *
+ * This file may be distributed and/or modified under the terms of the
+ * GNU General Public License version 2 as published by the Free Software
+ * Foundation and appearing in the file LICENSE.GPL included in the
+ * packaging of this file.
+ *
+ * Licensees holding valid libFirm Professional Edition licenses may use
+ * this file in accordance with the libFirm Commercial License.
+ * Agreement provided with the Software.
+ *
+ * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
+ * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE.
*/
+/**
+ * @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
+ * @version $Id$
+ */
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
+#ifdef HAVE_STRING_H
#include <string.h>
+#endif
#include "irloop_t.h"
#include "irnode_t.h"
/* 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) {
+/** Allocate a new scc_info on the obstack of the outermost graph */
+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;
}
+/**
+ * Marks the node n to be on the stack.
+ */
static INLINE void
mark_irn_in_stack (ir_node *n) {
- assert(get_irn_link(n));
- ((scc_info *)n->link)->in_stack = true;
+ scc_info *info = get_irn_link(n);
+ info->in_stack = 1;
}
+/**
+ * Marks the node n to be not on the stack.
+ */
static INLINE void
mark_irn_not_in_stack (ir_node *n) {
- assert(get_irn_link(n));
- ((scc_info *)n->link)->in_stack = false;
+ scc_info *info = get_irn_link(n);
+ info->in_stack = 0;
}
-static INLINE bool
+/**
+ * Returns whether node n is on the stack.
+ */
+static INLINE int
irn_is_in_stack (ir_node *n) {
- assert(get_irn_link(n));
- return ((scc_info *)n->link)->in_stack;
+ scc_info *info = get_irn_link(n);
+ return info->in_stack;
}
+/**
+ * Sets node n uplink value.
+ */
static INLINE void
set_irn_uplink (ir_node *n, int uplink) {
- assert(get_irn_link(n));
- ((scc_info *)n->link)->uplink = uplink;
+ scc_info *info = get_irn_link(n);
+ info->uplink = uplink;
}
+/**
+ * Return node n uplink value.
+ */
static INLINE int
get_irn_uplink (ir_node *n) {
- assert(get_irn_link(n));
- return ((scc_info *)n->link)->uplink;
+ scc_info *info = get_irn_link(n);
+ return info->uplink;
}
+/**
+ * Sets node n dfn value.
+ */
static INLINE void
set_irn_dfn (ir_node *n, int dfn) {
- assert(get_irn_link(n));
- ((scc_info *)n->link)->dfn = dfn;
+ scc_info *info = get_irn_link(n);
+ info->dfn = dfn;
}
+/**
+ * Returns node n dfn value.
+ */
static INLINE int
get_irn_dfn (ir_node *n) {
- assert(get_irn_link(n));
- return ((scc_info *)n->link)->dfn;
+ scc_info *info = get_irn_link(n);
+ return info->dfn;
}
/**********************************************************************/
/* A stack. **/
/**********************************************************************/
-static ir_node **stack = NULL;
-static int tos = 0; /* top of stack */
+static ir_node **stack = NULL; /**< An IR-node stack */
+static int tos = 0; /**< The top (index) of the IR-node stack */
+/**
+ * Initializes the IR-node stack
+ */
static INLINE void init_stack(void) {
if (stack) {
- ARR_RESIZE (ir_node *, stack, 1000);
+ ARR_RESIZE(ir_node *, stack, 1000);
} else {
- stack = NEW_ARR_F (ir_node *, 1000);
+ stack = NEW_ARR_F(ir_node *, 1000);
}
tos = 0;
}
-
+/**
+ * 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);
+ if (tos == ARR_LEN(stack)) {
+ int nlen = ARR_LEN(stack) * 2;
+ ARR_RESIZE(ir_node *, stack, nlen);
}
- stack [tos++] = n;
+ stack[tos++] = n;
mark_irn_in_stack(n);
}
+/**
+ * Pop a node from the IR-node stack and return it.
+ */
static INLINE ir_node *
pop (void)
{
return n;
}
-/* The nodes up to n belong to the current loop.
- Removes them from the stack and adds them to the current loop. */
+/**
+ * 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)
+pop_scc_to_loop(ir_node *n)
{
ir_node *m;
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. */
+/**
+ * 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) {
+ 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. */
+/**
+ * Allocates a new loop as son of current_loop. Sets current_loop
+ * to the new loop and returns its 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;
+ son = obstack_alloc(outermost_ir_graph->obst, sizeof(*son));
+ memset(son, 0, sizeof(*son));
+ 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;
if (son->depth > max_loop_depth) max_loop_depth = son->depth;
- } else { /* The root loop */
+ }
+ else { /* The root loop */
son->outer_loop = son;
- son->depth = 0;
+ son->depth = 0;
}
#ifdef DEBUG_libfirm
son->loop_nr = get_irp_new_node_nr();
- son->link = NULL;
+ son->link = NULL;
#endif
current_loop = son;
/* Initialization steps. **********************************************/
+/**
+ * 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) {
if (is_Block(n))
clear_backedges(n);
}
+/**
+ * Initializes the common global settings for the scc algorithm
+ */
static INLINE void
init_scc_common (void) {
- current_dfn = 1;
+ current_dfn = 1;
loop_node_cnt = 0;
init_stack();
}
+/**
+ * Initializes the scc algorithm for the intraprocedural case.
+ * Add scc info to every block node.
+ */
static INLINE void
init_scc (ir_graph *irg) {
init_scc_common();
- irg_walk_graph (irg, init_node, NULL, NULL);
+ irg_walk_graph(irg, init_node, NULL, NULL);
}
+/**
+ * Initializes the scc algorithm for the interprocedural case.
+ */
static INLINE void
init_ip_scc (void) {
init_scc_common();
#endif
}
-/* Condition for breaking the recursion. */
-static bool is_outermost_StartBlock(ir_node *n) {
+/**
+ * Condition for breaking the recursion: n is the block
+ * that gets the initial control flow from the Start node.
+ */
+static int 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 1;
}
- return false;
+ return 0;
}
-/** 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
+static int
is_head (ir_node *n, ir_node *root)
{
int i, arity;
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;
+ 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));
- }
- some_in_loop = 1;
+ if (get_irn_uplink(pred) < get_irn_uplink(root)) {
+ assert(get_irn_uplink(pred) >= get_irn_uplink(root));
+ }
+ some_in_loop = 1;
}
}
}
- return some_outof_loop && some_in_loop;
+ return some_outof_loop & some_in_loop;
}
-/* Returns true 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.
- @arg root: only needed for assertion. */
-static bool
+/**
+ * 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 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, arity;
assert(pred);
if (is_backedge(n, i)) { continue; }
if (!irn_is_in_stack(pred)) {
- some_outof_loop = 1; //printf(" some out of loop ");
+ some_outof_loop = 1; //printf(" some out of loop ");
} else {
- if(get_irn_uplink(pred) < get_irn_uplink(root)) {
- DDMN(pred); DDMN(root);
- assert(get_irn_uplink(pred) >= get_irn_uplink(root));
- }
- some_in_loop = 1;
+ if(get_irn_uplink(pred) < get_irn_uplink(root)) {
+ 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. */
+/**
+ * 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 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 (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);
+ 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 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 (is_backedge (n, i) || !irn_is_in_stack(pred))
+ continue;
if (get_irn_dfn(pred) > max) {
- index = i;
- max = get_irn_dfn(pred);
+ 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. */
+/**
+ * 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;
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))
+ (n == m))
return NULL;
} else {
if (m == n) return NULL;
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 = -1;
- }
- break;
+ 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 = -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. */
+ are not in this loop. We assume a loop not reachable from Start. */
if (m == n) {
- i = -1;
- break;
+ 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 (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. */
+ 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");
}
return is_outermost_StartBlock(n) ? NULL : get_nodes_block(skip_Proj(get_irn_n(m, res_index)));
}
+/**
+ * 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. *
*-----------------------------------------------------------*/
-
+/**
+ * Walks over all blocks of a graph
+ */
static void cfscc (ir_node *n) {
int i;
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
- 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;
+
+ if (is_backedge(n, i))
+ continue;
m = get_nodes_block(skip_Proj(get_irn_n(n, i)));
- cfscc (m);
+ 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));
+ /* 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));
}
}
}
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 */
+ because we found a cfloop head!
+ Next actions: Open a new cfloop on the cfloop tree and
+ try to find inner cfloops */
#if NO_CFLOOPS_WITHOUT_HEAD
ir_loop *l;
int close;
if ((get_loop_n_elements(current_loop) > 0) || (is_outermost_loop(current_loop))) {
- l = new_loop();
- close = 1;
+ l = new_loop();
+ close = 1;
} else {
- l = current_loop;
- close = 0;
+ l = current_loop;
+ close = 0;
}
#else
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. */
+ 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);
#if NO_CFLOOPS_WITHOUT_HEAD
if (close)
#endif
- close_loop(l);
+ 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. */
+ 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);
}
}
}
-/* Constructs backedge information for irg. */
+/* Constructs control flow backedge information for irg. */
int construct_cf_backedges(ir_graph *irg) {
ir_graph *rem = current_ir_graph;
ir_loop *head_rem;
int i;
assert(!get_interprocedural_view() &&
- "use construct_ip_backedges");
+ "use construct_ip_cf_backedges()");
max_loop_depth = 0;
- current_ir_graph = irg;
+ current_ir_graph = irg;
outermost_ir_graph = irg;
init_scc(current_ir_graph);
inc_irg_visited(current_ir_graph);
+ /* walk over all blocks of the graph, including keep alives */
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);
current_loop = NULL;
new_loop(); /* sets current_loop */
- set_interprocedural_view(true);
+ set_interprocedural_view(1);
inc_max_irg_visited();
for (i = 0; i < get_irp_n_irgs(); 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;
+ (get_nodes_block(get_Block_cfgpred(sb, 0)) != sb)) continue;
cfscc(get_irg_end_block(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);
+ ir_node *el = get_End_keepalive(e, j);
+ if (is_Block(el)) cfscc(el);
}
}
}
return max_loop_depth;
}
-
-static void reset_backedges(ir_node *n) {
- assert(is_Block(n));
+/**
+ * Clear the intra- and the interprocedural
+ * backedge information pf a block.
+ */
+static void reset_backedges(ir_node *block) {
int rem = get_interprocedural_view();
- set_interprocedural_view(true);
- clear_backedges(n);
- set_interprocedural_view(false);
- clear_backedges(n);
+
+ assert(is_Block(block));
+ set_interprocedural_view(1);
+ clear_backedges(block);
+ set_interprocedural_view(0);
+ clear_backedges(block);
set_interprocedural_view(rem);
}
+/**
+ * Reset all backedges of the first block of
+ * a loop as well as all loop info for all nodes of this loop.
+ * Recurse into all nested loops.
+ */
static void loop_reset_backedges(ir_loop *l) {
int i;
reset_backedges(get_loop_node(l, 0));
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);
+ set_irg_loopinfo_state(irg, loopinfo_none);
/* We cannot free the cfloop nodes, they are on the obstack. */
}
void free_all_cfloop_information (void) {
int i;
int rem = get_interprocedural_view();
- set_interprocedural_view(true); /* To visit all filter nodes */
- for (i = 0; i < get_irp_n_irgs(); i++) {
+ set_interprocedural_view(1); /* To visit all filter nodes */
+ for (i = get_irp_n_irgs() - 1; i >= 0; --i) {
free_cfloop_information(get_irp_irg(i));
}
set_interprocedural_view(rem);
projects / libfirm / blobdiff