X-Git-Url: http://nsz.repo.hu/git/?a=blobdiff_plain;f=ir%2Fbe%2Fbelistsched.c;h=2f11c874e4ab21d8374e2a863d574d2272095103;hb=a4cf97f91f44fcb14d08f9295bcdef8da372a54d;hp=12afe1c5ea52ad2250c4973541d8a456a07f8095;hpb=06e69d9797aaaeac65e2416cd3066ec40810e1ce;p=libfirm

diff --git a/ir/be/belistsched.c b/ir/be/belistsched.c
index 12afe1c5e..2f11c874e 100644
--- a/ir/be/belistsched.c
+++ b/ir/be/belistsched.c
@@ -4,6 +4,7 @@
  * @date 20.10.2004
  * @author Sebastian Hack
  */
+
 #ifdef HAVE_CONFIG_H
 #include "config.h"
 #endif
@@ -11,146 +12,575 @@
 #include <stdio.h>
 #include <stdarg.h>
 #include <string.h>
+#include <limits.h>
+
+#include "benode_t.h"
 
-#include "fourcc.h"
 #include "obst.h"
-#include "irouts.h"
+#include "list.h"
+#include "iterator.h"
+
+#include "iredges_t.h"
 #include "irgwalk.h"
 #include "irnode_t.h"
 #include "irmode_t.h"
-#include "list.h"
-#include "iterator.h"
 #include "irdump.h"
 #include "irprintf_t.h"
+#include "array.h"
 #include "debug.h"
+#include "irtools.h"
 
 #include "besched_t.h"
 #include "beutil.h"
+#include "belive_t.h"
 #include "belistsched.h"
+#include "beschedmris.h"
+#include "bearch.h"
+#include "bestat.h"
+
+/**
+ * All scheduling info needed per node.
+ */
+typedef struct _sched_irn_t {
+	sched_timestep_t delay;     /**< The delay for this node if already calculated, else 0. */
+	sched_timestep_t etime;     /**< The earliest time of this node. */
+	unsigned already_sched : 1; /**< Set if this node is already scheduled */
+	unsigned is_root       : 1; /**< is a root node of a block */
+} sched_irn_t;
 
 /**
  * Scheduling environment for the whole graph.
  */
 typedef struct _sched_env_t {
-    const ir_graph *irg;                        /**< The graph to schedule. */
-    const list_sched_selector_t *selector;		  /**< The node selector. */
-    void *selector_env;                         /**< A pointer to give to the selector. */
+	sched_irn_t *sched_info;                    /**< scheduling info per node */
+	const list_sched_selector_t *selector;      /**< The node selector. */
+	const arch_env_t *arch_env;                 /**< The architecture environment. */
+	const ir_graph *irg;                        /**< The graph to schedule. */
+	void *selector_env;                         /**< A pointer to give to the selector. */
 } sched_env_t;
 
-static ir_node *trivial_select(void *env, void *block_env, const struct list_head *sched_head,
-		int curr_time, pset *ready_set)
+#if 0
+/*
+ * Ugly global variable for the compare function
+ * since qsort(3) does not pass an extra pointer.
+ */
+static ir_node *curr_bl = NULL;
+
+static int cmp_usage(const void *a, const void *b)
+{
+	struct trivial_sched_env *env;
+	const ir_node *p = a;
+	const ir_node *q = b;
+	int res = 0;
+
+	res = is_live_end(env->curr_bl, a) - is_live_end(env->curr_bl, b);
+
+	/*
+	 * One of them is live at the end of the block.
+	 * Then, that one shall be scheduled at after the other
+	 */
+	if(res != 0)
+		return res;
+
+
+	return res;
+}
+#endif
+
+/**
+ * The trivial selector:
+ * Just assure that branches are executed last, otherwise select
+ * the first node ready.
+ */
+static ir_node *trivial_select(void *block_env, nodeset *ready_set)
+{
+	const arch_env_t *arch_env = block_env;
+	ir_node *irn = NULL;
+	int const_last = 0;
+
+	/* assure that branches and constants are executed last */
+	for (irn = nodeset_first(ready_set); irn; irn = nodeset_next(ready_set)) {
+		arch_irn_class_t irn_class = arch_irn_classify(arch_env, irn);
+
+		if (! arch_irn_class_is(arch_env, irn, branch) && (const_last ? (! arch_irn_class_is(arch_env, irn, const)) : 1)) {
+			nodeset_break(ready_set);
+			return irn;
+		}
+	}
+
+	/* assure that constants are executed before branches */
+	if (const_last) {
+		for (irn = nodeset_first(ready_set); irn; irn = nodeset_next(ready_set)) {
+			if (! arch_irn_class_is(arch_env, irn, branch)) {
+				nodeset_break(ready_set);
+				return irn;
+			}
+		}
+	}
+
+
+	/* at last: schedule branches */
+	irn = nodeset_first(ready_set);
+	nodeset_break(ready_set);
+
+	return irn;
+}
+
+static void *trivial_init_graph(const list_sched_selector_t *vtab, const arch_env_t *arch_env, ir_graph *irg)
 {
-    ir_node *res = pset_first(ready_set);
-    pset_break(ready_set);
-    return res;
+	return (void *) arch_env;
+}
+
+static void *trivial_init_block(void *graph_env, ir_node *bl)
+{
+	return graph_env;
+}
+
+static INLINE int must_appear_in_schedule(const list_sched_selector_t *sel, void *block_env, const ir_node *irn)
+{
+	int res = -1;
+
+	if(sel->to_appear_in_schedule)
+		res = sel->to_appear_in_schedule(block_env, irn);
+
+	return res >= 0 ? res : (to_appear_in_schedule(irn) || be_is_Keep(irn) || be_is_RegParams(irn));
 }
 
 static const list_sched_selector_t trivial_selector_struct = {
-	NULL,
-	NULL,
+	trivial_init_graph,
+	trivial_init_block,
 	trivial_select,
-	NULL,
-	NULL
+	NULL,                /* to_appear_in_schedule */
+	NULL,                /* exectime */
+	NULL,                /* latency */
+	NULL,                /* finish_block */
+	NULL                 /* finish_graph */
 };
 
 const list_sched_selector_t *trivial_selector = &trivial_selector_struct;
 
-static void list_sched_block(ir_node *block, void *env_ptr);
+typedef struct _usage_stats_t {
+	ir_node *irn;
+	struct _usage_stats_t *next;
+	int max_hops;
+	int uses_in_block;      /**< Number of uses inside the current block. */
+	int already_consumed;   /**< Number of insns using this value already
+							  scheduled. */
+} usage_stats_t;
+
+typedef struct {
+	const list_sched_selector_t *vtab;
+	const arch_env_t *arch_env;
+} reg_pressure_main_env_t;
+
+typedef struct {
+	struct obstack obst;
+	const reg_pressure_main_env_t *main_env;
+	usage_stats_t *root;
+	nodeset *already_scheduled;
+} reg_pressure_selector_env_t;
+
+static INLINE usage_stats_t *get_or_set_usage_stats(reg_pressure_selector_env_t *env, ir_node *irn)
+{
+	usage_stats_t *us = get_irn_link(irn);
+
+	if(!us) {
+		us                   = obstack_alloc(&env->obst, sizeof(us[0]));
+		us->irn              = irn;
+		us->already_consumed = 0;
+		us->max_hops         = INT_MAX;
+		us->next             = env->root;
+		env->root            = us;
+		set_irn_link(irn, us);
+	}
+
+	return us;
+}
+
+static INLINE usage_stats_t *get_usage_stats(ir_node *irn)
+{
+	usage_stats_t *us = get_irn_link(irn);
+	assert(us && "This node must have usage stats");
+	return us;
+}
+
+static int max_hops_walker(reg_pressure_selector_env_t *env, ir_node *irn, ir_node *curr_bl, int depth, unsigned visited_nr)
+{
+	ir_node *bl = get_nodes_block(irn);
+	/*
+	 * If the reached node is not in the block desired,
+	 * return the value passed for this situation.
+	 */
+	if(get_nodes_block(irn) != bl)
+		return block_dominates(bl, curr_bl) ? 0 : INT_MAX;
+
+	/*
+	 * If the node is in the current block but not
+	 * yet scheduled, we keep on searching from that node.
+	 */
+	if(!nodeset_find(env->already_scheduled, irn)) {
+		int i, n;
+		int res = 0;
+		for(i = 0, n = get_irn_arity(irn); i < n; ++i) {
+			ir_node *operand = get_irn_n(irn, i);
+
+			if(get_irn_visited(operand) < visited_nr) {
+				int tmp;
+
+				set_irn_visited(operand, visited_nr);
+				tmp = max_hops_walker(env, operand, bl, depth + 1, visited_nr);
+				res = MAX(tmp, res);
+			}
+		}
+
+		return res;
+	}
+
+	/*
+	 * If the node is in the current block and scheduled, return
+	 * the depth which indicates the number of steps to the
+	 * region of scheduled nodes.
+	 */
+	return depth;
+}
+
+static int compute_max_hops(reg_pressure_selector_env_t *env, ir_node *irn)
+{
+	ir_node *bl   = get_nodes_block(irn);
+	ir_graph *irg = get_irn_irg(bl);
+	int res       = 0;
+
+	const ir_edge_t *edge;
+
+	foreach_out_edge(irn, edge) {
+		ir_node *user       = get_edge_src_irn(edge);
+		unsigned visited_nr = get_irg_visited(irg) + 1;
+		int max_hops;
+
+		set_irg_visited(irg, visited_nr);
+		max_hops = max_hops_walker(env, user, irn, 0, visited_nr);
+		res      = MAX(res, max_hops);
+	}
+
+	return res;
+}
+
+static void *reg_pressure_graph_init(const list_sched_selector_t *vtab, const arch_env_t *arch_env, ir_graph *irg)
+{
+	reg_pressure_main_env_t *main_env = xmalloc(sizeof(main_env[0]));
+
+	main_env->arch_env = arch_env;
+	main_env->vtab     = vtab;
+	irg_walk_graph(irg, firm_clear_link, NULL, NULL);
+
+	return main_env;
+}
+
+static void *reg_pressure_block_init(void *graph_env, ir_node *bl)
+{
+	ir_node *irn;
+	reg_pressure_selector_env_t *env  = xmalloc(sizeof(env[0]));
+
+	obstack_init(&env->obst);
+	env->already_scheduled = new_nodeset(32);
+	env->root              = NULL;
+	env->main_env          = graph_env;
+
+	/*
+	 * Collect usage statistics.
+	 */
+	sched_foreach(bl, irn) {
+		if(must_appear_in_schedule(env->main_env->vtab, env, irn)) {
+			int i, n;
+
+			for(i = 0, n = get_irn_arity(irn); i < n; ++i) {
+				//ir_node *op = get_irn_n(irn, i);
+				if(must_appear_in_schedule(env->main_env->vtab, env, irn)) {
+					usage_stats_t *us = get_or_set_usage_stats(env, irn);
+#if 0 /* Liveness is not computed here! */
+					if(is_live_end(bl, op))
+						us->uses_in_block = 99999;
+					else
+#endif
+						us->uses_in_block++;
+				}
+			}
+		}
+	}
+
+	return env;
+}
 
-void list_sched(ir_graph *irg, const list_sched_selector_t *selector)
+static void reg_pressure_block_free(void *block_env)
 {
-    sched_env_t env;
+	reg_pressure_selector_env_t *env = block_env;
+	usage_stats_t *us;
 
-    memset(&env, 0, sizeof(env));
-    env.selector = selector;
-    env.selector_env = selector->init_graph ? selector->init_graph(irg) : NULL;
-    env.irg = irg;
+	for(us = env->root; us; us = us->next)
+		set_irn_link(us->irn, NULL);
 
-    /* Normalize proj nodes. */
-    normalize_proj_nodes(irg);
+	obstack_free(&env->obst, NULL);
+	del_nodeset(env->already_scheduled);
+	free(env);
+}
 
-    /* Compute the outs */
-    if(get_irg_outs_state(irg) != outs_consistent)
-        compute_outs(irg);
+static int get_result_hops_sum(reg_pressure_selector_env_t *env, ir_node *irn)
+{
+	int res = 0;
+	if(get_irn_mode(irn) == mode_T) {
+		const ir_edge_t *edge;
+
+		foreach_out_edge(irn, edge)
+			res += get_result_hops_sum(env, get_edge_src_irn(edge));
+	}
 
-    /* Dump the graph. */
-    //dump_ir_block_graph(irg, "-before-sched");
+	else if(mode_is_data(get_irn_mode(irn)))
+		res = compute_max_hops(env, irn);
 
-    /* Schedule each single block. */
-    irg_block_walk_graph(irg, list_sched_block, NULL, &env);
 
-		if(selector->finish_graph)
-			selector->finish_graph(env.selector_env, irg);
+	return res;
 }
 
+static INLINE int reg_pr_costs(reg_pressure_selector_env_t *env, ir_node *irn)
+{
+	int i, n;
+	int sum = 0;
+
+	for(i = 0, n = get_irn_arity(irn); i < n; ++i) {
+		ir_node *op = get_irn_n(irn, i);
+
+		if(must_appear_in_schedule(env->main_env->vtab, env, op))
+			sum += compute_max_hops(env, op);
+	}
+
+	sum += get_result_hops_sum(env, irn);
+
+	return sum;
+}
+
+static ir_node *reg_pressure_select(void *block_env, nodeset *ready_set)
+{
+	reg_pressure_selector_env_t *env = block_env;
+	ir_node *irn, *res     = NULL;
+	int curr_cost          = INT_MAX;
+
+	assert(nodeset_count(ready_set) > 0);
+
+	for (irn = nodeset_first(ready_set); irn; irn = nodeset_next(ready_set)) {
+		/*
+			Ignore branch instructions for the time being.
+			They should only be scheduled if there is nothing else.
+		*/
+		if (! arch_irn_class_is(env->main_env->arch_env, irn, branch)) {
+			int costs = reg_pr_costs(env, irn);
+			if (costs <= curr_cost) {
+				res       = irn;
+				curr_cost = costs;
+			}
+		}
+	}
+
+	/*
+		There was no result so we only saw a branch.
+		Take it and finish.
+	*/
+
+	if(!res) {
+		res = nodeset_first(ready_set);
+		nodeset_break(ready_set);
+
+		assert(res && "There must be a node scheduled.");
+	}
+
+	nodeset_insert(env->already_scheduled, res);
+	return res;
+}
 
 /**
  * Environment for a block scheduler.
  */
 typedef struct _block_sched_env_t {
-    int curr_time;
-    pset *ready_set;
-    pset *already_scheduled;
-    ir_node *block;
-		firm_dbg_module_t *dbg;
+	sched_irn_t *sched_info;                    /**< scheduling info per node, copied from the global scheduler object */
+	sched_timestep_t curr_time;                 /**< current time of the scheduler */
+	nodeset *cands;                             /**< the set of candidates */
+	ir_node *block;                             /**< the current block */
+	sched_env_t *sched_env;                     /**< the scheduler environment */
+	const list_sched_selector_t *selector;
+	void *selector_block_env;
+	DEBUG_ONLY(firm_dbg_module_t *dbg;)
 } block_sched_env_t;
 
+/**
+ * Returns non-zero if the node is already scheduled
+ */
+static INLINE int is_already_scheduled(block_sched_env_t *env, ir_node *n)
+{
+	int idx = get_irn_idx(n);
+
+	assert(idx < ARR_LEN(env->sched_info));
+	return env->sched_info[idx].already_sched;
+}
+
+/**
+ * Mark a node as already scheduled
+ */
+static INLINE void mark_already_scheduled(block_sched_env_t *env, ir_node *n)
+{
+	int idx = get_irn_idx(n);
 
+	assert(idx < ARR_LEN(env->sched_info));
+	env->sched_info[idx].already_sched = 1;
+}
 
+/**
+ * Returns non-zero if the node is a root node
+ */
+static INLINE unsigned is_root_node(block_sched_env_t *env, ir_node *n)
+{
+	int idx = get_irn_idx(n);
+
+	assert(idx < ARR_LEN(env->sched_info));
+	return env->sched_info[idx].is_root;
+}
+
+/**
+ * Mark a node as roto node
+ */
+static INLINE void mark_root_node(block_sched_env_t *env, ir_node *n)
+{
+	int idx = get_irn_idx(n);
+
+	assert(idx < ARR_LEN(env->sched_info));
+	env->sched_info[idx].is_root = 1;
+}
+
+/**
+ * Get the current delay.
+ */
+static sched_timestep_t get_irn_delay(block_sched_env_t *env, ir_node *n) {
+	int idx = get_irn_idx(n);
+
+	assert(idx < ARR_LEN(env->sched_info));
+	return env->sched_info[idx].delay;
+}
+
+/**
+ * Set the current delay.
+ */
+static void set_irn_delay(block_sched_env_t *env, ir_node *n, sched_timestep_t delay) {
+	int idx = get_irn_idx(n);
+
+	assert(idx < ARR_LEN(env->sched_info));
+	env->sched_info[idx].delay = delay;
+}
+
+/**
+ * Get the current etime.
+ */
+static sched_timestep_t get_irn_etime(block_sched_env_t *env, ir_node *n) {
+	int idx = get_irn_idx(n);
+
+	assert(idx < ARR_LEN(env->sched_info));
+	return env->sched_info[idx].etime;
+}
+
+/**
+ * Set the current etime.
+ */
+static void set_irn_etime(block_sched_env_t *env, ir_node *n, sched_timestep_t etime) {
+	int idx = get_irn_idx(n);
+
+	assert(idx < ARR_LEN(env->sched_info));
+	env->sched_info[idx].etime = etime;
+}
+
+/**
+ * returns the exec-time for node n.
+ */
+static sched_timestep_t exectime(sched_env_t *env, ir_node *n) {
+  if (be_is_Keep(n) || is_Proj(n))
+    return 0;
+	if (env->selector->exectime)
+		return env->selector->exectime(env->selector_env, n);
+	return 1;
+}
+
+/**
+ * Calculates the latency for between two ops
+ */
+static sched_timestep_t latency(sched_env_t *env, ir_node *pred, int pred_cycle, ir_node *curr, int curr_cycle) {
+	/* a Keep hides a root */
+  if (be_is_Keep(curr))
+		return exectime(env, pred);
+
+	/* Proj's are executed immediately */
+	if (is_Proj(curr))
+    return 0;
+
+	/* predecessors Proj's must be skipped */
+  if (is_Proj(pred))
+    pred = get_Proj_pred(pred);
+
+	if (env->selector->latency)
+		return env->selector->latency(env->selector_env, pred, pred_cycle, curr, curr_cycle);
+	return 1;
+}
 
 /**
  * Try to put a node in the ready set.
- * @param env The block scheduler environment.
- * @param irn The node to make ready.
+ * @param env   The block scheduler environment.
+ * @param pred  The previous scheduled node.
+ * @param irn   The node to make ready.
  * @return 1, if the node could be made ready, 0 else.
  */
-static INLINE int make_ready(block_sched_env_t *env, ir_node *irn)
+static INLINE int make_ready(block_sched_env_t *env, ir_node *pred, ir_node *irn)
 {
     int i, n;
+		sched_timestep_t etime_p, etime;
 
     /* Blocks cannot be scheduled. */
-    if(is_Block(irn))
+    if (is_Block(irn))
         return 0;
 
     /*
      * Check, if the given ir node is in a different block as the
      * currently scheduled one. If that is so, don't make the node ready.
      */
-    if(env->block != get_nodes_block(irn))
+    if (env->block != get_nodes_block(irn))
         return 0;
 
-    for(i = 0, n = get_irn_arity(irn); i < n; ++i) {
+    for (i = 0, n = get_irn_arity(irn); i < n; ++i) {
         ir_node *op = get_irn_n(irn, i);
 
+        /* if irn is an End we have keep-alives and op might be a block, skip that */
+        if (is_Block(op)) {
+          assert(get_irn_op(irn) == op_End);
+          continue;
+        }
+
         /* If the operand is local to the scheduled block and not yet
          * scheduled, this nodes cannot be made ready, so exit. */
-        if(!pset_find_ptr(env->already_scheduled, op) && get_nodes_block(op) == env->block)
+        if (!is_already_scheduled(env, op) && get_nodes_block(op) == env->block)
             return 0;
     }
 
-    DBG((env->dbg, LEVEL_2, "\tmaking ready: %+F\n", irn));
-    pset_insert_ptr(env->ready_set, irn);
+    nodeset_insert(env->cands, irn);
 
-    return 1;
-}
+		/* calculate the etime of this node */
+		etime = env->curr_time;
+		if (pred) {
+			etime_p  = get_irn_etime(env, pred);
+			etime   += latency(env->sched_env, pred, 1, irn, 0);
 
-/**
- * Check, if a node is ready in a block schedule.
- * @param env The block schedule environment.
- * @param irn The node to check for.
- * @return 1 if the node was ready, 0 if not.
- */
-#define is_ready(env,irn) \
-  (pset_find_ptr((env)->ready_set, irn) != NULL)
+			etime = etime_p > etime ? etime_p : etime;
+		}
 
-/**
- * Check, if a node has already been schedules.
- * @param env The block schedule environment.
- * @param irn The node to check for.
- * @return 1 if the node was already scheduled, 0 if not.
- */
-#define is_scheduled(env,irn) \
-  (pset_find_ptr((env)->already_scheduled, irn) != NULL)
+		set_irn_etime(env, irn, etime);
+
+    DB((env->dbg, LEVEL_2, "\tmaking ready: %+F etime %u\n", irn, etime));
+
+    return 1;
+}
 
 /**
  * Try, to make all users of a node ready.
@@ -161,37 +591,26 @@ static INLINE int make_ready(block_sched_env_t *env, ir_node *irn)
  */
 static INLINE void make_users_ready(block_sched_env_t *env, ir_node *irn)
 {
-    int i, n;
-
-    for(i = 0, n = get_irn_n_outs(irn); i < n; ++i) {
-        ir_node *user = get_irn_out(irn, i);
-				if(!is_Phi(user))
-					make_ready(env, user);
-    }
-}
+	const ir_edge_t *edge;
 
-/**
- * Compare to nodes using pointer equality.
- * @param p1 Node one.
- * @param p2 Node two.
- * @return 0 if they are identical.
- */
-static int node_cmp_func(const void *p1, const void *p2)
-{
-    return p1 != p2;
+	foreach_out_edge(irn, edge) {
+		ir_node *user = edge->src;
+		if(!is_Phi(user))
+			make_ready(env, irn, user);
+	}
 }
 
 /**
  * Append an instruction to a schedule.
- * @param env The block scheduleing environment.
+ * @param env The block scheduling environment.
  * @param irn The node to add to the schedule.
- * @return The given node.
+ * @return    The given node.
  */
 static ir_node *add_to_sched(block_sched_env_t *env, ir_node *irn)
 {
     /* If the node consumes/produces data, it is appended to the schedule
      * list, otherwise, it is not put into the list */
-    if(to_appear_in_schedule(irn)) {
+    if(must_appear_in_schedule(env->selector, env->selector_block_env, irn)) {
         sched_info_t *info = get_irn_sched_info(irn);
         INIT_LIST_HEAD(&info->list);
         info->scheduled = 1;
@@ -201,16 +620,15 @@ static ir_node *add_to_sched(block_sched_env_t *env, ir_node *irn)
     }
 
     /* Insert the node in the set of all already scheduled nodes. */
-    pset_insert_ptr(env->already_scheduled, irn);
+    mark_already_scheduled(env, irn);
 
     /* Remove the node from the ready set */
-    if(pset_find_ptr(env->ready_set, irn))
-        pset_remove_ptr(env->ready_set, irn);
+    if(nodeset_find(env->cands, irn))
+        nodeset_remove(env->cands, irn);
 
     return irn;
 }
 
-
 /**
  * Add the proj nodes of a tuple-mode irn to the schedule immediately
  * after the tuple-moded irn. By pinning the projs after the irn, no
@@ -220,32 +638,104 @@ static ir_node *add_to_sched(block_sched_env_t *env, ir_node *irn)
  * values.
  *
  * @param irn The tuple-moded irn.
- * @param list The schedule list to append all the projs.
- * @param time The time step to which the irn and all its projs are
- * related to.
- * @param obst The obstack the scheduling data structures shall be
- * created upon.
- * @param ready_set The ready set of the list scheduler.
- * @param already_scheduled A set containing all nodes already
- * scheduled.
  */
 static void add_tuple_projs(block_sched_env_t *env, ir_node *irn)
 {
-    int i, n;
-    assert(get_irn_mode(irn) == mode_T && "Mode of node must be tuple");
+	const ir_edge_t *edge;
 
-    for(i = 0, n = get_irn_n_outs(irn); i < n; ++i) {
-        ir_node *out = get_irn_out(irn, i);
+	assert(get_irn_mode(irn) == mode_T && "Mode of node must be tuple");
 
-        assert(is_Proj(out) && "successor of a modeT node must be a proj");
+	if(is_Bad(irn))
+		return;
 
-        if(get_irn_mode(out) == mode_T)
-            add_tuple_projs(env, out);
-        else {
-            add_to_sched(env, out);
-            make_users_ready(env, out);
-        }
-    }
+	foreach_out_edge(irn, edge) {
+		ir_node *out = edge->src;
+
+		assert(is_Proj(out) && "successor of a modeT node must be a proj");
+
+		if (get_irn_mode(out) == mode_T)
+			add_tuple_projs(env, out);
+		else {
+			add_to_sched(env, out);
+			make_users_ready(env, out);
+		}
+	}
+}
+
+/**
+ * Execute the heuristic function,
+ */
+static ir_node *select_node_heuristic(block_sched_env_t *be, nodeset *ns)
+{
+	ir_node *irn;
+
+	for (irn = nodeset_first(ns); irn; irn = nodeset_next(ns)) {
+		if (be_is_Keep(irn)) {
+			nodeset_break(ns);
+			return irn;
+		}
+	}
+
+	return be->selector->select(be->selector_block_env, ns);
+}
+
+/**
+ * Returns non-zero if root is a root in the block block.
+ */
+static int is_root(ir_node *root, ir_node *block) {
+	const ir_edge_t *edge;
+
+	foreach_out_edge(root, edge) {
+		ir_node *succ = get_edge_src_irn(edge);
+
+		if (is_Block(succ))
+			continue;
+		/* Phi nodes are always in "another block */
+		if (is_Phi(succ))
+			continue;
+		if (get_nodes_block(succ) == block)
+			return 0;
+	}
+	return 1;
+}
+
+/* we need a special mark */
+static char _mark;
+#define MARK	&_mark
+
+static firm_dbg_module_t *xxxdbg;
+
+/**
+ * descent into a dag and create a pre-order list.
+ */
+static void descent(ir_node *root, ir_node *block, ir_node **list) {
+	int i;
+
+	if (! is_Phi(root)) {
+		/* Phi nodes always leave the block */
+		for (i = get_irn_arity(root) - 1; i >= 0; --i) {
+			ir_node *pred = get_irn_n(root, i);
+
+			DBG((xxxdbg, LEVEL_3, "   node %+F\n", pred));
+			/* Blocks may happen as predecessors of End nodes */
+			if (is_Block(pred))
+				continue;
+
+			/* already seen nodes are not marked */
+			if (get_irn_link(pred) != MARK)
+				continue;
+
+			/* don't leave our block */
+			if (get_nodes_block(pred) != block)
+				continue;
+
+			set_irn_link(pred, NULL);
+
+			descent(pred, block, list);
+		}
+	}
+	set_irn_link(root, *list);
+	*list = root;
 }
 
 /**
@@ -257,106 +747,287 @@ static void add_tuple_projs(block_sched_env_t *env, ir_node *irn)
  * Also the outs must have been computed.
  *
  * @param block The block node.
- * @param env Schedulting environment.
+ * @param env Scheduling environment.
  */
 static void list_sched_block(ir_node *block, void *env_ptr)
 {
-	void *block_env = NULL;
-	sched_env_t *env = env_ptr;
-	block_sched_env_t be;
+	sched_env_t *env                      = env_ptr;
 	const list_sched_selector_t *selector = env->selector;
+	ir_node *start_node                   = get_irg_start(get_irn_irg(block));
+	sched_info_t *info                    = get_irn_sched_info(block);
 
+	block_sched_env_t be;
+	const ir_edge_t *edge;
 	ir_node *irn;
-	int i, n, j, m;
-	int phi_seen = 0;
-	sched_info_t *info = get_irn_sched_info(block);
+	int j, m;
+
+	ir_node *root = NULL, *preord = NULL;
+	ir_node *curr;
 
 	/* Initialize the block's list head that will hold the schedule. */
 	INIT_LIST_HEAD(&info->list);
 
 	/* Initialize the block scheduling environment */
-	be.dbg = firm_dbg_register("firm.be.sched");
-	be.block = block;
-	be.curr_time = 0;
-	be.ready_set = new_pset(node_cmp_func, get_irn_n_outs(block));
-	be.already_scheduled = new_pset(node_cmp_func, get_irn_n_outs(block));
+	be.sched_info        = env->sched_info;
+	be.block             = block;
+	be.curr_time         = 0;
+	be.cands             = new_nodeset(get_irn_n_edges(block));
+	be.selector          = selector;
+	be.sched_env         = env;
+	FIRM_DBG_REGISTER(be.dbg, "firm.be.sched");
+	FIRM_DBG_REGISTER(xxxdbg, "firm.be.sched");
 
-  firm_dbg_set_mask(be.dbg, 0);
+	//	firm_dbg_set_mask(be.dbg, SET_LEVEL_3);
 
-	if(selector->init_block)
-		block_env = selector->init_block(env->selector_env, block);
+	if (selector->init_block)
+		be.selector_block_env = selector->init_block(env->selector_env, block);
 
 	DBG((be.dbg, LEVEL_1, "scheduling %+F\n", block));
 
+	/* First step: Find the root set. */
+	foreach_out_edge(block, edge) {
+		ir_node *succ = get_edge_src_irn(edge);
+
+		if (is_root(succ, block)) {
+			mark_root_node(&be, succ);
+			set_irn_link(succ, root);
+			root = succ;
+		}
+		else
+			set_irn_link(succ, MARK);
+	}
+
+	/* Second step: calculate the pre-order list. */
+	preord = NULL;
+	for (curr = root; curr; curr = irn) {
+		irn = get_irn_link(curr);
+		DBG((be.dbg, LEVEL_2, "   DAG root %+F\n", curr));
+		descent(curr, block, &preord);
+	}
+	root = preord;
+
+	/* Third step: calculate the Delay. Note that our
+	* list is now in pre-order, starting at root
+	*/
+	for (curr = root; curr; curr = get_irn_link(curr)) {
+		sched_timestep_t d;
+
+		if (arch_irn_class_is(env->arch_env, curr, branch)) {
+			/* assure, that branches can be executed last */
+			d = 0;
+		}
+		else {
+			if (is_root_node(&be, curr))
+				d = exectime(env, curr);
+			else {
+				d = 0;
+				foreach_out_edge(curr, edge) {
+					ir_node *n = get_edge_src_irn(edge);
+
+					if (get_nodes_block(n) == block) {
+						sched_timestep_t ld;
+
+						ld = latency(env, curr, 1, n, 0) + get_irn_delay(&be, n);
+						d = ld > d ? ld : d;
+					}
+				}
+			}
+		}
+		set_irn_delay(&be, curr, d);
+		DB((be.dbg, LEVEL_2, "\t%+F delay %u\n", curr, d));
+
+		/* set the etime of all nodes to 0 */
+		set_irn_etime(&be, curr, 0);
+	}
+
+
 	/* Then one can add all nodes are ready to the set. */
-	for(i = 0, n = get_irn_n_outs(block); i < n; ++i) {
-		ir_node *irn = get_irn_out(block, i);
+	foreach_out_edge(block, edge) {
+		ir_node *irn = get_edge_src_irn(edge);
 
 		/* Skip the end node because of keepalive edges. */
-		if(get_irn_opcode(irn) == iro_End)
+		if (get_irn_opcode(irn) == iro_End)
 			continue;
 
-		/* Phi functions are scheduled immediately, since they only transfer
-		 * data flow from the predecessors to this block. */
-		if(is_Phi(irn)) {
+		if (is_Phi(irn)) {
+			/* Phi functions are scheduled immediately, since they only transfer
+			* data flow from the predecessors to this block. */
+
+			/* Increase the time step. */
+			be.curr_time += get_irn_etime(&be, irn);
 			add_to_sched(&be, irn);
 			make_users_ready(&be, irn);
-			phi_seen = 1;
 		}
+		else if (irn == start_node) {
+			/* The start block will be scheduled as the first node */
+			be.curr_time += get_irn_etime(&be, irn);
 
-		/* Other nodes must have all operands in other blocks to be made
-		 * ready */
+			add_to_sched(&be, irn);
+			add_tuple_projs(&be, irn);
+		}
 		else {
-			bool ready = true;
+			/* Other nodes must have all operands in other blocks to be made
+			* ready */
+			int ready = 1;
 
 			/* Check, if the operands of a node are not local to this block */
-			for(j = 0, m = get_irn_arity(irn); j < m; ++j) {
+			for (j = 0, m = get_irn_arity(irn); j < m; ++j) {
 				ir_node *operand = get_irn_n(irn, j);
 
-				if(get_nodes_block(operand) == block) {
-					ready = false;
+				if (get_nodes_block(operand) == block) {
+					ready = 0;
 					break;
 				}
 			}
 
 			/* Make the node ready, if all operands live in a foreign block */
-			if(ready) {
+			if (ready) {
 				DBG((be.dbg, LEVEL_2, "\timmediately ready: %+F\n", irn));
-				make_ready(&be, irn);
+				make_ready(&be, NULL, irn);
 			}
 		}
 	}
 
-	/* Increase the time, if some phi functions have been scheduled */
-	be.curr_time += phi_seen;
+	while (nodeset_count(be.cands) > 0) {
+		nodeset *mcands;                            /**< the set of candidates with maximum delay time */
+		nodeset *ecands;                            /**< the set of nodes in mcands whose etime <= curr_time  */
+		sched_timestep_t max_delay = 0;
 
-	while(pset_count(be.ready_set) > 0) {
-		// DBG((be.dbg, LEVEL_2, "\tready set: %*n\n", pset_iterator, be.ready_set));
+		/* collect statistics about amount of ready nodes */
+		be_do_stat_sched_ready(block, be.cands);
 
-		/* select a node to be scheduled and check if it was ready */
-		irn = selector->select(env->selector_env, block_env, &info->list, be.curr_time, be.ready_set);
+		/* calculate the max delay of all candidates */
+		foreach_nodeset(be.cands, irn) {
+			sched_timestep_t d = get_irn_delay(&be, irn);
 
-		DBG((be.dbg, LEVEL_3, "\tpicked node %+F\n", irn));
+			max_delay = d > max_delay ? d : max_delay;
+		}
+		mcands = new_nodeset(8);
+		ecands = new_nodeset(8);
+
+		/* calculate mcands and ecands */
+		foreach_nodeset(be.cands, irn) {
+			if (be_is_Keep(irn)) {
+				nodeset_break(be.cands);
+				break;
+			}
+			if (get_irn_delay(&be, irn) == max_delay) {
+				nodeset_insert(mcands, irn);
+				if (get_irn_etime(&be, irn) <= be.curr_time)
+					nodeset_insert(ecands, irn);
+			}
+		}
+
+		if (irn) {
+			/* Keeps must be immediately scheduled */
+		}
+		else {
+			DB((be.dbg, LEVEL_2, "\tbe.curr_time = %u\n", be.curr_time));
+
+			/* select a node to be scheduled and check if it was ready */
+			if (nodeset_count(mcands) == 1) {
+				DB((be.dbg, LEVEL_3, "\tmcand = 1, max_delay = %u\n", max_delay));
+				irn = nodeset_first(mcands);
+			}
+			else {
+				int cnt = nodeset_count(ecands);
+				if (cnt == 1) {
+					irn = nodeset_first(ecands);
+
+					if (arch_irn_class_is(env->arch_env, irn, branch)) {
+						/* BEWARE: don't select a JUMP if others are still possible */
+						goto force_mcands;
+					}
+					DB((be.dbg, LEVEL_3, "\tecand = 1, max_delay = %u\n", max_delay));
+				}
+				else if (cnt > 1) {
+					DB((be.dbg, LEVEL_3, "\tecand = %d, max_delay = %u\n", cnt, max_delay));
+					irn = select_node_heuristic(&be, ecands);
+				}
+				else {
+force_mcands:
+					DB((be.dbg, LEVEL_3, "\tmcand = %d\n", nodeset_count(mcands)));
+					irn = select_node_heuristic(&be, mcands);
+				}
+			}
+		}
+		del_nodeset(mcands);
+		del_nodeset(ecands);
+
+		DB((be.dbg, LEVEL_2, "\tpicked node %+F\n", irn));
+
+		/* Increase the time step. */
+		be.curr_time += exectime(env, irn);
 
 		/* Add the node to the schedule. */
 		add_to_sched(&be, irn);
 
-		if(get_irn_mode(irn) == mode_T)
+		if (get_irn_mode(irn) == mode_T)
 			add_tuple_projs(&be, irn);
 		else
 			make_users_ready(&be, irn);
 
-		/* Increase the time step. */
-		be.curr_time += 1;
-
 		/* remove the scheduled node from the ready list. */
-		if(pset_find_ptr(be.ready_set, irn))
-			pset_remove_ptr(be.ready_set, irn);
+		if (nodeset_find(be.cands, irn))
+			nodeset_remove(be.cands, irn);
 	}
 
-	if(selector->finish_block)
-		selector->finish_block(env->selector_env, block_env, block);
+	if (selector->finish_block)
+		selector->finish_block(be.selector_block_env);
+
+	del_nodeset(be.cands);
+}
+
+static const list_sched_selector_t reg_pressure_selector_struct = {
+	reg_pressure_graph_init,
+	reg_pressure_block_init,
+	reg_pressure_select,
+	NULL,                    /* to_appear_in_schedule */
+	NULL,                    /* exectime */
+	NULL,                    /* latency */
+	reg_pressure_block_free,
+	free
+};
+
+const list_sched_selector_t *reg_pressure_selector = &reg_pressure_selector_struct;
+
+/* List schedule a graph. */
+void list_sched(const be_irg_t *birg, int enable_mris)
+{
+	const arch_env_t *arch_env = birg->main_env->arch_env;
+	ir_graph *irg              = birg->irg;
+
+	int num_nodes;
+	sched_env_t env;
+	mris_env_t *mris;
+
+	/* Assure, that the out edges are computed */
+	edges_assure(irg);
+
+	if(enable_mris)
+		mris = be_sched_mris_preprocess(birg);
+
+	num_nodes = get_irg_last_idx(irg);
+
+	memset(&env, 0, sizeof(env));
+	env.selector   = arch_env->isa->impl->get_list_sched_selector(arch_env->isa);
+	env.arch_env   = arch_env;
+	env.irg        = irg;
+	env.sched_info = NEW_ARR_F(sched_irn_t, num_nodes);
+
+	memset(env.sched_info, 0, num_nodes * sizeof(*env.sched_info));
+
+	if (env.selector->init_graph)
+		env.selector_env = env.selector->init_graph(env.selector, arch_env, irg);
+
+	/* Schedule each single block. */
+	irg_block_walk_graph(irg, list_sched_block, NULL, &env);
+
+	if (env.selector->finish_graph)
+		env.selector->finish_graph(env.selector_env);
+
+	if(enable_mris)
+		be_sched_mris_free(mris);
 
-	del_pset(be.ready_set);
-	del_pset(be.already_scheduled);
+	DEL_ARR_F(env.sched_info);
 }