irn classify is now a mask
[libfirm] / ir / be / belistsched.c
index 8358986..2f11c87 100644 (file)
 #include "irmode_t.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"
 
-#define MAX(x,y) ((x) > (y) ? (x) : (y))
-#define MIN(x,y) ((x) < (y) ? (x) : (y))
+/**
+ * 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 {
+       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 enviromnent. */
+       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;
@@ -84,15 +96,30 @@ 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 are executed last */
+       /* assure that branches and constants are executed last */
        for (irn = nodeset_first(ready_set); irn; irn = nodeset_next(ready_set)) {
-               if (arch_irn_classify(arch_env, irn) != arch_irn_class_branch) {
+               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);
 
@@ -111,21 +138,23 @@ static void *trivial_init_block(void *graph_env, ir_node *bl)
 
 static INLINE int must_appear_in_schedule(const list_sched_selector_t *sel, void *block_env, const ir_node *irn)
 {
-       int res = 0;
+       int res = -1;
 
        if(sel->to_appear_in_schedule)
                res = sel->to_appear_in_schedule(block_env, irn);
 
-       return res || to_appear_in_schedule(irn) || be_is_Keep(irn) || be_is_RegParams(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 = {
        trivial_init_graph,
        trivial_init_block,
        trivial_select,
-       NULL,
-       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;
@@ -265,12 +294,14 @@ static void *reg_pressure_block_init(void *graph_env, ir_node *bl)
                        int i, n;
 
                        for(i = 0, n = get_irn_arity(irn); i < n; ++i) {
-                               ir_node *op = get_irn_n(irn, 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++;
                                }
                        }
@@ -340,7 +371,7 @@ static ir_node *reg_pressure_select(void *block_env, nodeset *ready_set)
                        Ignore branch instructions for the time being.
                        They should only be scheduled if there is nothing else.
                */
-               if (arch_irn_classify(env->main_env->arch_env, irn) != arch_irn_class_branch) {
+               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;
@@ -365,77 +396,160 @@ static ir_node *reg_pressure_select(void *block_env, nodeset *ready_set)
        return res;
 }
 
-static const list_sched_selector_t reg_pressure_selector_struct = {
-       reg_pressure_graph_init,
-       reg_pressure_block_init,
-       reg_pressure_select,
-       NULL,
-       reg_pressure_block_free,
-       free
-};
+/**
+ * Environment for a block scheduler.
+ */
+typedef struct _block_sched_env_t {
+       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;
 
-const list_sched_selector_t *reg_pressure_selector = &reg_pressure_selector_struct;
+/**
+ * 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);
 
-static void list_sched_block(ir_node *block, void *env_ptr);
+       assert(idx < ARR_LEN(env->sched_info));
+       return env->sched_info[idx].already_sched;
+}
 
-void list_sched(const arch_env_t *arch_env, ir_graph *irg)
+/**
+ * Mark a node as already scheduled
+ */
+static INLINE void mark_already_scheduled(block_sched_env_t *env, ir_node *n)
 {
-       sched_env_t env;
+       int idx = get_irn_idx(n);
 
-       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;
+       assert(idx < ARR_LEN(env->sched_info));
+       env->sched_info[idx].already_sched = 1;
+}
 
-       if(env.selector->init_graph)
-               env.selector_env = env.selector->init_graph(env.selector, arch_env, irg);
+/**
+ * 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);
 
-       /* Assure, that the out edges are computed */
-       edges_assure(irg);
+       assert(idx < ARR_LEN(env->sched_info));
+       return env->sched_info[idx].is_root;
+}
 
-       /* Schedule each single block. */
-       irg_block_walk_graph(irg, list_sched_block, NULL, &env);
+/**
+ * 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);
 
-       if(env.selector->finish_graph)
-               env.selector->finish_graph(env.selector_env);
+       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;
+}
 
 /**
- * Environment for a block scheduler.
+ * Get the current etime.
  */
-typedef struct _block_sched_env_t {
-       int curr_time;
-       nodeset *ready_set;
-       nodeset *already_scheduled;
-       ir_node *block;
-       const list_sched_selector_t *selector;
-       void *selector_block_env;
-       DEBUG_ONLY(firm_dbg_module_t *dbg;)
-} block_sched_env_t;
+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 */
@@ -446,33 +560,27 @@ static INLINE int make_ready(block_sched_env_t *env, ir_node *irn)
 
         /* If the operand is local to the scheduled block and not yet
          * scheduled, this nodes cannot be made ready, so exit. */
-        if(!nodeset_find(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));
-    nodeset_insert(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) \
-  (nodeset_find((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) \
-  (nodeset_find((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.
@@ -488,21 +596,10 @@ static INLINE void make_users_ready(block_sched_env_t *env, ir_node *irn)
        foreach_out_edge(irn, edge) {
                ir_node *user = edge->src;
                if(!is_Phi(user))
-                       make_ready(env, user);
+                       make_ready(env, irn, user);
        }
 }
 
-/**
- * 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;
-}
-
 /**
  * Append an instruction to a schedule.
  * @param env The block scheduling environment.
@@ -523,11 +620,11 @@ 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. */
-    nodeset_insert(env->already_scheduled, irn);
+    mark_already_scheduled(env, irn);
 
     /* Remove the node from the ready set */
-    if(nodeset_find(env->ready_set, irn))
-        nodeset_remove(env->ready_set, irn);
+    if(nodeset_find(env->cands, irn))
+        nodeset_remove(env->cands, irn);
 
     return irn;
 }
@@ -541,14 +638,6 @@ 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)
 {
@@ -556,12 +645,15 @@ static void add_tuple_projs(block_sched_env_t *env, ir_node *irn)
 
        assert(get_irn_mode(irn) == mode_T && "Mode of node must be tuple");
 
+       if(is_Bad(irn))
+               return;
+
        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)
+               if (get_irn_mode(out) == mode_T)
                        add_tuple_projs(env, out);
                else {
                        add_to_sched(env, out);
@@ -570,18 +662,80 @@ static void add_tuple_projs(block_sched_env_t *env, ir_node *irn)
        }
 }
 
-static ir_node *select_node(block_sched_env_t *be)
+/**
+ * Execute the heuristic function,
+ */
+static ir_node *select_node_heuristic(block_sched_env_t *be, nodeset *ns)
 {
        ir_node *irn;
 
-       for (irn = nodeset_first(be->ready_set); irn; irn = nodeset_next(be->ready_set)) {
+       for (irn = nodeset_first(ns); irn; irn = nodeset_next(ns)) {
                if (be_is_Keep(irn)) {
-                       nodeset_break(be->ready_set);
+                       nodeset_break(ns);
                        return irn;
                }
        }
 
-       return be->selector->select(be->selector_block_env, be->ready_set);
+       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;
 }
 
 /**
@@ -600,7 +754,6 @@ static void list_sched_block(ir_node *block, void *env_ptr)
        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));
-       int phi_seen                          = 0;
        sched_info_t *info                    = get_irn_sched_info(block);
 
        block_sched_env_t be;
@@ -608,96 +761,273 @@ static void list_sched_block(ir_node *block, void *env_ptr)
        ir_node *irn;
        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.sched_info        = env->sched_info;
        be.block             = block;
        be.curr_time         = 0;
-       be.ready_set         = new_nodeset(get_irn_n_edges(block));
-       be.already_scheduled = new_nodeset(get_irn_n_edges(block));
+       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");
 
-       if(selector->init_block)
+       //      firm_dbg_set_mask(be.dbg, SET_LEVEL_3);
+
+       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. */
        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);
 
-               /* The start block will be scheduled as the first node */
-               else if(irn == start_node) {
                        add_to_sched(&be, irn);
                        add_tuple_projs(&be, irn);
                }
-
-
-               /* Other nodes must have all operands in other blocks to be made
-                * ready */
                else {
+                       /* 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) {
+                               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;
+
+               /* collect statistics about amount of ready nodes */
+               be_do_stat_sched_ready(block, be.cands);
+
+               /* calculate the max delay of all candidates */
+               foreach_nodeset(be.cands, irn) {
+                       sched_timestep_t d = get_irn_delay(&be, irn);
 
-       while (nodeset_count(be.ready_set) > 0) {
-               /* select a node to be scheduled and check if it was ready */
-               irn = select_node(&be);
+                       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));
 
-               DBG((be.dbg, LEVEL_3, "\tpicked node %+F\n", irn));
+                       /* 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 (nodeset_find(be.ready_set, irn))
-                       nodeset_remove(be.ready_set, irn);
+               if (nodeset_find(be.cands, irn))
+                       nodeset_remove(be.cands, irn);
        }
 
-       if(selector->finish_block)
+       if (selector->finish_block)
                selector->finish_block(be.selector_block_env);
 
-       del_nodeset(be.ready_set);
-       del_nodeset(be.already_scheduled);
+       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_ARR_F(env.sched_info);
 }