+/*
+ * Project: libFIRM
+ * File name: ir/ana/irextbb2.c
+ * Purpose: Alternate extended basic block computation
+ * Author: Matthias Braun
+ * Modified by:
+ * Created: 5.2005
+ * CVS-ID: $Id$
+ * Copyright: (c) 2002-2005 Universität Karlsruhe
+ * Licence: This file protected by GPL - GNU GENERAL PUBLIC LICENSE.
+ */
+
+/**
+ * @file irextbb.c
+ *
+ * Alternative algorithm for computing extended basic blocks (using out edges
+ * and execution frequencies)
+ *
+ * @author Matthias Braun
+ */
+#include "irextbb_t.h"
+#include "irgwalk.h"
+#include "irnode_t.h"
+#include "irgraph_t.h"
+#include "iredges_t.h"
+#include "irouts.h"
+#include "xmalloc.h"
+#include "irprintf.h"
+#include "execfreq.h"
+
+typedef struct _env {
+ struct obstack *obst; /**< the obstack where allocations took place */
+ ir_extblk *head; /**< head of the list of all extended blocks */
+ exec_freq_t *execfreqs;
+} env_t;
+
+/**
+ * allocate a new extended block header.
+ */
+static ir_extblk *allocate_extblk(ir_node *block, env_t *env)
+{
+ ir_extblk *extblk = obstack_alloc(env->obst, sizeof(*extblk));
+
+ extblk->kind = k_ir_extblk;
+ extblk->visited = 1;
+ extblk->blks = (ir_node **)env->head;
+ extblk->link = block;
+ env->head = extblk;
+
+ set_Block_extbb(block, extblk);
+ set_irn_link(block, NULL);
+
+ return extblk;
+}
+
+/**
+ * add a block to an extended block
+ */
+static void addto_extblk(ir_extblk *extblk, ir_node *block)
+{
+ /* link all blocks belonging to this extended block */
+ set_irn_link(block, extblk->link);
+
+ extblk->link = block;
+ extblk->visited++;
+
+ set_Block_extbb(block, extblk);
+}
+
+/**
+ * Returns the number of block successors.
+ * we are interested only in 1, 2 and >2.
+ */
+static int get_block_n_succs(ir_node *block) {
+ if (edges_activated(current_ir_graph)) {
+ const ir_edge_t *edge;
+
+ edge = get_block_succ_first(block);
+ if (! edge)
+ return 0;
+ edge = get_block_succ_next(block, edge);
+ if (! edge)
+ return 1;
+ edge = get_block_succ_next(block, edge);
+ return edge ? 3 : 2;
+ }
+
+ return get_Block_n_cfg_outs(block);
+}
+
+static void pick_successor(ir_node *block, ir_extblk *extblk, env_t *env);
+
+static void create_extblk(ir_node *block, env_t *env)
+{
+ if(irn_visited(block))
+ return;
+
+ ir_extblk *extblk = allocate_extblk(block, env);
+ mark_irn_visited(block);
+
+ pick_successor(block, extblk, env);
+}
+
+static void pick_successor(ir_node *block, ir_extblk *extblk, env_t *env)
+{
+ const ir_edge_t *edge;
+ ir_node *best_succ = NULL;
+ double best_execfreq = -1;
+
+ /* More than two successors means we have a jump table.
+ * we cannot include a jump target into the current extended
+ * basic block, so create a new one here.
+ */
+ if(get_block_n_succs(block) > 2) {
+ const ir_edge_t *edge;
+
+ foreach_block_succ(block, edge) {
+ ir_node *succ = get_edge_src_irn(edge);
+ create_extblk(succ, env);
+ }
+
+ return;
+ }
+
+ foreach_block_succ(block, edge) {
+ ir_node *succ = get_edge_src_irn(edge);
+ double execfreq;
+
+ if(get_Block_n_cfgpreds(succ) > 1) {
+ create_extblk(succ, env);
+ continue;
+ }
+
+ execfreq = get_block_execfreq(env->execfreqs, succ);
+
+ // remember best sucessor and make non best successor with only 1
+ // pred block to new extbb leaders
+ if(execfreq > best_execfreq) {
+ if(best_succ != NULL) {
+ create_extblk(best_succ, env);
+ }
+
+ best_execfreq = execfreq;
+ best_succ = succ;
+ } else {
+ create_extblk(succ, env);
+ }
+ }
+
+ // add best successor and recursively try to pick more
+ if(best_succ != NULL) {
+ addto_extblk(extblk, best_succ);
+ mark_irn_visited(best_succ);
+ pick_successor(best_succ, extblk, env);
+ }
+}
+
+/*
+ * Compute the extended basic blocks for a graph
+ */
+void compute_extbb_execfreqs(ir_graph *irg, exec_freq_t *execfreqs) {
+ env_t env;
+ ir_extblk *extbb, *next;
+ ir_node *endblock;
+
+ if (irg->extbb_obst) {
+ obstack_free(irg->extbb_obst, NULL);
+ } else {
+ irg->extbb_obst = xmalloc(sizeof(*irg->extbb_obst));
+ }
+ obstack_init(irg->extbb_obst);
+
+ env.obst = irg->extbb_obst;
+ env.head = NULL;
+ env.execfreqs = execfreqs;
+
+ assure_irg_outs(irg);
+
+ /* we must mark nodes, so increase the visited flag */
+ inc_irg_visited(irg);
+ create_extblk(get_irg_start_block(irg), &env);
+
+ // the end block needs a extbb assigned (even for endless loops)
+ endblock = get_irg_end_block(irg);
+ if(!irn_visited(endblock)) {
+ create_extblk(endblock, &env);
+ }
+
+ /*
+ * Ok, we have now the list of all extended blocks starting with env.head
+ * every extended block "knowns" the number of blocks in visited and
+ * the blocks are linked in link.
+ * Now we can create arrays that hold the blocks, some kind of "out" edges
+ * for the extended block
+ */
+ for (extbb = env.head; extbb; extbb = next) {
+ int i, len = (int)extbb->visited;
+ ir_node *block;
+
+ next = (ir_extblk *)extbb->blks;
+
+ extbb->blks = NEW_ARR_D(ir_node *, env.obst, len);
+
+ for (block = extbb->link, i = 0; i < len; ++i) {
+ ir_node *nblock = get_irn_link(block);
+
+ /* ensure that the leader is the first one */
+ extbb->blks[len - 1 - i] = block;
+ set_irn_link(block, NULL);
+ block = nblock;
+ }
+
+ for(i = 0; i < len; ++i) {
+ if(i > 0)
+ printf(", ");
+ ir_printf("%+F", extbb->blks[i]);
+ }
+ printf("\n");
+
+ extbb->link = NULL;
+ extbb->visited = 0;
+ }
+
+ irg->extblk_state = extblk_valid;
+}