remove #if 0 around arch_get_irn_ops, no idea why it was there...
[libfirm] / ir / be / becopyheur4.c
index 32b3348..42bdee7 100644 (file)
 #include "raw_bitset.h"
 #include "irphase_t.h"
 #include "pqueue.h"
-#include "pset_new.h"
 #include "xmalloc.h"
 #include "pdeq.h"
+#include "pset.h"
 #include "irprintf.h"
+#include "irbitset.h"
+#include "error.h"
+#include "list.h"
+#include "statev.h"
+
 #include "irbitset.h"
 
 #include "bearch.h"
 #include "becopyopt_t.h"
 #include "bemodule.h"
 
-DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)
 
 #define COL_COST_INFEASIBLE       DBL_MAX
 #define AFF_NEIGHBOUR_FIX_BENEFIT 128.0
 #define NEIGHBOUR_CONSTR_COSTS    64.0
 
-#define DBG_AFF_CHUNK(env, level, chunk) DEBUG_ONLY(do { if (firm_dbg_get_mask(dbg) & (level)) dbg_aff_chunk((env), (chunk)); } while(0))
-#define DBG_COL_COST(env, level, cost)   DEBUG_ONLY(do { if (firm_dbg_get_mask(dbg) & (level)) dbg_col_cost((env), (cost)); } while(0))
 
-static int last_chunk_id = 0;
+#ifdef DEBUG_libfirm
+
+#define DBG_AFF_CHUNK(env, level, chunk) do { if (firm_dbg_get_mask(dbg) & (level)) dbg_aff_chunk((env), (chunk)); } while(0)
+#define DBG_COL_COST(env, level, cost)   do { if (firm_dbg_get_mask(dbg) & (level)) dbg_col_cost((env), (cost)); } while(0)
+
+static firm_dbg_module_t *dbg = NULL;
+
+#else
+
+#define DBG_AFF_CHUNK(env, level, chunk)
+#define DBG_COL_COST(env, level, cost)
+
+#endif
+
+static int last_chunk_id        = 0;
+static int recolor_limit        = 4;
+static double dislike_influence = 0.1;
 
 typedef struct _col_cost_t {
        int    col;
@@ -73,18 +91,23 @@ typedef struct _col_cost_t {
  * An affinity chunk.
  */
 typedef struct _aff_chunk_t {
-       bitset_t *nodes;                /**< A bitset containing all nodes inside this chunk. */
-       int      weight;                /**< Weight of this chunk */
-       unsigned weight_consistent : 1; /**< Set if the weight is consistent. */
-       int      id;                    /**< For debugging: An id of this chunk. */
+       const ir_node    **n;                   /**< An ARR_F containing all nodes of the chunk. */
+       bitset_t         *nodes;                /**< A bitset containing all nodes inside this chunk. */
+       bitset_t         *interfere;            /**< A bitset containing all interfering neighbours of the nodes in this chunk. */
+       int              weight;                /**< Weight of this chunk */
+       unsigned         weight_consistent : 1; /**< Set if the weight is consistent. */
+       unsigned         deleted           : 1; /**< Set if the was deleted. */
+       int              id;                    /**< For debugging: An id of this chunk. */
+       int              visited;
+       col_cost_t       *color_affinity;
 } aff_chunk_t;
 
 /**
  * An affinity edge.
  */
 typedef struct _aff_edge_t {
-       ir_node *src;                   /**< Source node. */
-       ir_node *tgt;                   /**< Target node. */
+       const ir_node *src;                   /**< Source node. */
+       const ir_node *tgt;                   /**< Target node. */
        double  weight;                 /**< The weight of this edge. */
 } aff_edge_t;
 
@@ -93,41 +116,43 @@ typedef struct _co_mst_env_t {
        int              n_regs;         /**< number of regs in class */
        int              k;              /**< number of non-ignore registers in class */
        bitset_t         *ignore_regs;   /**< set containing all global ignore registers */
-       int              *map_regs;      /**< map the available colors to the available registers */
        ir_phase         ph;             /**< phase object holding data for nodes */
        pqueue           *chunks;        /**< priority queue for chunks */
-       pset_new_t       chunkset;       /**< set holding all chunks */
+       pset             *chunkset;      /**< set holding all chunks */
        be_ifg_t         *ifg;           /**< the interference graph */
        const arch_env_t *aenv;          /**< the arch environment */
        copy_opt_t       *co;            /**< the copy opt object */
+       int               chunk_visited;
+       col_cost_t      **single_cols;
 } co_mst_env_t;
 
 /* stores coalescing related information for a node */
 typedef struct _co_mst_irn_t {
-       ir_node     *irn;              /**< the irn this information belongs to */
-       aff_chunk_t *chunk;            /**< the chunk this irn belongs to */
-       bitset_t    *adm_colors;       /**< set of admissible colors for this irn */
-       ir_node     **int_neighs;      /**< array of all interfering neighbours (cached for speed reasons) */
-       int         n_neighs;          /**< length of the interfering neighbours array. */
-       int         int_aff_neigh;     /**< number of interfering affinity neighbours */
-       int         col;               /**< color currently assigned */
-       int         init_col;          /**< the initial color */
-       int         tmp_col;           /**< a temporary assigned color */
-       unsigned    fixed     : 1;     /**< the color is fixed */
-       unsigned    tmp_fixed : 1;     /**< the color is temporary fixed */
+       const ir_node    *irn;              /**< the irn this information belongs to */
+       aff_chunk_t      *chunk;            /**< the chunk this irn belongs to */
+       bitset_t         *adm_colors;       /**< set of admissible colors for this irn */
+       ir_node          **int_neighs;      /**< array of all interfering neighbours (cached for speed reasons) */
+       int              n_neighs;          /**< length of the interfering neighbours array. */
+       int              int_aff_neigh;     /**< number of interfering affinity neighbours */
+       int              col;               /**< color currently assigned */
+       int              init_col;          /**< the initial color */
+       int              tmp_col;           /**< a temporary assigned color */
+       unsigned         fixed     : 1;     /**< the color is fixed */
+       struct list_head list;              /**< Queue for coloring undo. */
+       double           constr_factor;
 } co_mst_irn_t;
 
 #define get_co_mst_irn(mst_env, irn) (phase_get_or_set_irn_data(&(mst_env)->ph, (irn)))
 
-typedef int decide_func_t(co_mst_irn_t *node, int col);
+typedef int decide_func_t(const co_mst_irn_t *node, int col);
 
 #ifdef DEBUG_libfirm
 
 /**
  * Write a chunk to stderr for debugging.
  */
-static void dbg_aff_chunk(co_mst_env_t *env, aff_chunk_t *c) {
-       int idx;
+static void dbg_aff_chunk(const co_mst_env_t *env, const aff_chunk_t *c) {
+       bitset_pos_t idx;
        if (c->weight_consistent)
                ir_fprintf(stderr, " $%d ", c->weight);
        ir_fprintf(stderr, "{");
@@ -141,8 +166,10 @@ static void dbg_aff_chunk(co_mst_env_t *env, aff_chunk_t *c) {
 /**
  * Dump all admissible colors to stderr.
  */
-static void dbg_admissible_colors(co_mst_env_t *env, co_mst_irn_t *node) {
-       int idx;
+static void dbg_admissible_colors(const co_mst_env_t *env, const co_mst_irn_t *node) {
+       bitset_pos_t idx;
+       (void) env;
+
        if (bitset_popcnt(node->adm_colors) < 1)
                fprintf(stderr, "no admissible colors?!?");
        else {
@@ -154,40 +181,38 @@ static void dbg_admissible_colors(co_mst_env_t *env, co_mst_irn_t *node) {
 /**
  * Dump color-cost pairs to stderr.
  */
-static void dbg_col_cost(co_mst_env_t *env, col_cost_t *cost) {
+static void dbg_col_cost(const co_mst_env_t *env, const col_cost_t *cost) {
        int i;
-       for (i = 0; i < env->n_regs; ++i) {
-               if (cost[i].cost == COL_COST_INFEASIBLE)
-                       fprintf(stderr, " (%d, INF)", cost[i].col);
-               else
-                       fprintf(stderr, " (%d, %.1f)", cost[i].col, cost[i].cost);
-       }
+       for (i = 0; i < env->n_regs; ++i)
+               fprintf(stderr, " (%d, %.4f)", cost[i].col, cost[i].cost);
 }
 
 #endif /* DEBUG_libfirm */
 
-static INLINE int get_mst_irn_col(co_mst_irn_t *node) {
-       return node->tmp_fixed ? node->tmp_col : node->col;
+static INLINE int get_mst_irn_col(const co_mst_irn_t *node) {
+       return node->tmp_col >= 0 ? node->tmp_col : node->col;
 }
 
 /**
  * @return 1 if node @p node has color @p col, 0 otherwise.
  */
-static int decider_has_color(co_mst_irn_t *node, int col) {
+static int decider_has_color(const co_mst_irn_t *node, int col) {
        return get_mst_irn_col(node) == col;
 }
 
 /**
  * @return 1 if node @p node has not color @p col, 0 otherwise.
  */
-static int decider_hasnot_color(co_mst_irn_t *node, int col) {
+static int decider_hasnot_color(const co_mst_irn_t *node, int col) {
        return get_mst_irn_col(node) != col;
 }
 
 /**
  * Always returns true.
  */
-static int decider_always_yes(co_mst_irn_t *node, int col) {
+static int decider_always_yes(const co_mst_irn_t *node, int col) {
+       (void) node;
+       (void) col;
        return 1;
 }
 
@@ -207,11 +232,18 @@ static int cmp_aff_edge(const void *a, const void *b) {
 }
 
 /** compares to color-cost pairs */
-static int cmp_col_cost(const void *a, const void *b) {
+static __attribute__((unused)) int cmp_col_cost_lt(const void *a, const void *b) {
        const col_cost_t *c1 = a;
        const col_cost_t *c2 = b;
+       double diff = c1->cost - c2->cost;
+       return (diff > 0) - (diff < 0);
+}
 
-       return c1->cost < c2->cost ? -1 : 1;
+static int cmp_col_cost_gt(const void *a, const void *b) {
+       const col_cost_t *c1 = a;
+       const col_cost_t *c2 = b;
+       double diff = c2->cost - c1->cost;
+       return (diff > 0) - (diff < 0);
 }
 
 /**
@@ -221,9 +253,13 @@ static INLINE aff_chunk_t *new_aff_chunk(co_mst_env_t *env) {
        aff_chunk_t *c = xmalloc(sizeof(*c));
        c->weight            = -1;
        c->weight_consistent = 0;
+       c->n                 = NEW_ARR_F(const ir_node *, 0);
        c->nodes             = bitset_irg_malloc(env->co->irg);
+       c->interfere         = bitset_irg_malloc(env->co->irg);
+       c->color_affinity    = xmalloc(env->n_regs * sizeof(c->color_affinity[0]));
        c->id                = last_chunk_id++;
-       pset_new_insert(&env->chunkset, c);
+       c->visited           = 0;
+       pset_insert(env->chunkset, c, c->id);
        return c;
 }
 
@@ -231,8 +267,12 @@ static INLINE aff_chunk_t *new_aff_chunk(co_mst_env_t *env) {
  * Frees all memory allocated by an affinity chunk.
  */
 static INLINE void delete_aff_chunk(co_mst_env_t *env, aff_chunk_t *c) {
-       pset_new_remove(&env->chunkset, c);
+       pset_remove(env->chunkset, c, c->id);
        bitset_free(c->nodes);
+       bitset_free(c->interfere);
+       xfree(c->color_affinity);
+       DEL_ARR_F(c->n);
+       c->deleted = 1;
        free(c);
 }
 
@@ -240,19 +280,31 @@ static INLINE void delete_aff_chunk(co_mst_env_t *env, aff_chunk_t *c) {
  * Adds a node to an affinity chunk
  */
 static INLINE void aff_chunk_add_node(aff_chunk_t *c, co_mst_irn_t *node) {
+       int i;
+
+       if (bitset_is_set(c->nodes, get_irn_idx(node->irn)))
+               return;
+
        c->weight_consistent = 0;
        node->chunk          = c;
        bitset_set(c->nodes, get_irn_idx(node->irn));
+
+       ARR_APP1(ir_node *, c->n, node->irn);
+
+       for (i = node->n_neighs - 1; i >= 0; --i) {
+               ir_node *neigh = node->int_neighs[i];
+               bitset_set(c->interfere, get_irn_idx(neigh));
+       }
 }
 
 /**
  * In case there is no phase information for irn, initialize it.
  */
-static void *co_mst_irn_init(ir_phase *ph, ir_node *irn, void *old) {
+static void *co_mst_irn_init(ir_phase *ph, const ir_node *irn, void *old) {
        co_mst_irn_t *res = old ? old : phase_alloc(ph, sizeof(res[0]));
        co_mst_env_t *env = ph->priv;
 
-       if (res != old) {
+       if (!old) {
                const arch_register_req_t *req;
                void     *nodes_it = be_ifg_nodes_iter_alloca(env->ifg);
                ir_node  *neigh;
@@ -261,12 +313,12 @@ static void *co_mst_irn_init(ir_phase *ph, ir_node *irn, void *old) {
                res->irn           = irn;
                res->chunk         = NULL;
                res->fixed         = 0;
-               res->tmp_fixed     = 0;
                res->tmp_col       = -1;
                res->int_neighs    = NULL;
                res->int_aff_neigh = 0;
                res->col           = arch_register_get_index(arch_get_irn_register(env->aenv, irn));
                res->init_col      = res->col;
+               INIT_LIST_HEAD(&res->list);
 
                DB((dbg, LEVEL_4, "Creating phase info for %+F\n", irn));
 
@@ -283,14 +335,19 @@ static void *co_mst_irn_init(ir_phase *ph, ir_node *irn, void *old) {
                /* exclude global ignore registers as well */
                bitset_andnot(res->adm_colors, env->ignore_regs);
 
+               /* compute the constraint factor */
+               res->constr_factor = (double) (1 + env->n_regs - bitset_popcnt(res->adm_colors)) / env->n_regs;
+
                /* set the number of interfering affinity neighbours to -1, they are calculated later */
                res->int_aff_neigh = -1;
 
                /* build list of interfering neighbours */
                len = 0;
                be_ifg_foreach_neighbour(env->ifg, nodes_it, irn, neigh) {
-                       obstack_ptr_grow(phase_obst(ph), neigh);
-                       ++len;
+                       if (! arch_irn_is(env->aenv, neigh, ignore)) {
+                               obstack_ptr_grow(phase_obst(ph), neigh);
+                               ++len;
+                       }
                }
                res->int_neighs = obstack_finish(phase_obst(ph));
                res->n_neighs   = len;
@@ -301,18 +358,9 @@ static void *co_mst_irn_init(ir_phase *ph, ir_node *irn, void *old) {
 /**
  * Check if affinity chunk @p chunk interferes with node @p irn.
  */
-static INLINE int aff_chunk_interferes(co_mst_env_t *env, aff_chunk_t *chunk, ir_node *irn) {
-       co_mst_irn_t *node = get_co_mst_irn(env, irn);
-       ir_node      *neigh;
-       int          i;
-
-       for (i = 0; i < node->n_neighs; ++i) {
-               neigh = node->int_neighs[i];
-               if (! arch_irn_is(env->aenv, neigh, ignore) && bitset_is_set(chunk->nodes, get_irn_idx(neigh)))
-                       return 1;
-       }
-
-       return 0;
+static INLINE int aff_chunk_interferes(co_mst_env_t *env, const aff_chunk_t *chunk, const ir_node *irn) {
+       (void) env;
+       return bitset_is_set(chunk->interfere, get_irn_idx(irn));
 }
 
 /**
@@ -322,28 +370,20 @@ static INLINE int aff_chunk_interferes(co_mst_env_t *env, aff_chunk_t *chunk, ir
  * @param c2    Another chunk
  * @return 1 if there are interferences between nodes of c1 and c2, 0 otherwise.
  */
-static INLINE int aff_chunks_interfere(co_mst_env_t *env, aff_chunk_t *c1, aff_chunk_t *c2) {
-       int idx;
-
+static INLINE int aff_chunks_interfere(co_mst_env_t *env, const aff_chunk_t *c1, const aff_chunk_t *c2) {
+       (void) env;
        if (c1 == c2)
                return 0;
 
        /* check if there is a node in c2 having an interfering neighbor in c1 */
-       bitset_foreach(c2->nodes, idx) {
-               ir_node *n = get_idx_irn(env->co->irg, idx);
-
-               if (aff_chunk_interferes(env, c1, n))
-                       return 1;
-       }
-
-       return 0;
+       return bitset_intersect(c1->interfere, c2->nodes);
 }
 
 /**
  * Returns the affinity chunk of @p irn or creates a new
  * one with @p irn as element if there is none assigned.
  */
-static INLINE aff_chunk_t *get_aff_chunk(co_mst_env_t *env, ir_node *irn) {
+static INLINE aff_chunk_t *get_aff_chunk(co_mst_env_t *env, const ir_node *irn) {
        co_mst_irn_t *node = get_co_mst_irn(env, irn);
        return node->chunk;
 }
@@ -353,11 +393,11 @@ static INLINE aff_chunk_t *get_aff_chunk(co_mst_env_t *env, ir_node *irn) {
  * are no interference edges from chunk(src) to chunk(tgt)).
  * @return 1 if successful, 0 if not possible
  */
-static int aff_chunk_absorb(co_mst_env_t *env, ir_node *src, ir_node *tgt) {
+static int aff_chunk_absorb(co_mst_env_t *env, const ir_node *src, const ir_node *tgt) {
        aff_chunk_t *c1 = get_aff_chunk(env, src);
        aff_chunk_t *c2 = get_aff_chunk(env, tgt);
 
-       DEBUG_ONLY(
+#ifdef DEBUG_libfirm
                DB((dbg, LEVEL_4, "Attempt to let c1 (id %d): ", c1 ? c1->id : -1));
                if (c1) {
                        DBG_AFF_CHUNK(env, LEVEL_4, c1);
@@ -371,7 +411,7 @@ static int aff_chunk_absorb(co_mst_env_t *env, ir_node *src, ir_node *tgt) {
                        DB((dbg, LEVEL_4, "{%+F}", tgt));
                }
                DB((dbg, LEVEL_4, "\n"));
-       )
+#endif
 
        if (c1 == NULL) {
                if (c2 == NULL) {
@@ -404,16 +444,13 @@ static int aff_chunk_absorb(co_mst_env_t *env, ir_node *src, ir_node *tgt) {
                        goto absorbed;
                }
        } else if (c1 != c2 && ! aff_chunks_interfere(env, c1, c2)) {
-               int idx;
+               int idx, len;
 
-               bitset_or(c1->nodes, c2->nodes);
-               c1->weight_consistent = 0;
+               for (idx = 0, len = ARR_LEN(c2->n); idx < len; ++idx)
+                       aff_chunk_add_node(c1, get_co_mst_irn(env, c2->n[idx]));
 
-               bitset_foreach(c2->nodes, idx) {
-                       ir_node      *n  = get_idx_irn(env->co->irg, idx);
-                       co_mst_irn_t *mn = get_co_mst_irn(env, n);
-                       mn->chunk = c1;
-               }
+               bitset_or(c1->interfere, c2->interfere);
+               c1->weight_consistent = 0;
 
                delete_aff_chunk(env, c2);
                goto absorbed;
@@ -432,17 +469,30 @@ absorbed:
 static void aff_chunk_assure_weight(co_mst_env_t *env, aff_chunk_t *c) {
        if (! c->weight_consistent) {
                int w = 0;
-               int idx;
+               int idx, len, i;
+
+               for (i = 0; i < env->n_regs; ++i) {
+                       c->color_affinity[i].col = i;
+                       c->color_affinity[i].cost = 0.0;
+               }
 
-               bitset_foreach(c->nodes, idx) {
-                       ir_node         *n  = get_idx_irn(env->co->irg, idx);
-                       affinity_node_t *an = get_affinity_info(env->co, n);
+               for (idx = 0, len = ARR_LEN(c->n); idx < len; ++idx) {
+                       const ir_node         *n       = c->n[idx];
+                       const affinity_node_t *an      = get_affinity_info(env->co, n);
+                       co_mst_irn_t          *node    = get_co_mst_irn(env, n);
+
+                       node->chunk = c;
+                       if (node->constr_factor > 0.0) {
+                               bitset_pos_t col;
+                               bitset_foreach (node->adm_colors, col)
+                                       c->color_affinity[col].cost += node->constr_factor;
+                       }
 
                        if (an != NULL) {
                                neighb_t *neigh;
                                co_gs_foreach_neighb(an, neigh) {
-                                       ir_node      *m    = neigh->irn;
-                                       int          m_idx = get_irn_idx(m);
+                                       const ir_node *m    = neigh->irn;
+                                       const int     m_idx = get_irn_idx(m);
 
                                        /* skip ignore nodes */
                                        if (arch_irn_is(env->aenv, m, ignore))
@@ -453,7 +503,11 @@ static void aff_chunk_assure_weight(co_mst_env_t *env, aff_chunk_t *c) {
                        }
                }
 
+               for (i = 0; i < env->n_regs; ++i)
+                       c->color_affinity[i].cost *= (1.0 / ARR_LEN(c->n));
+
                c->weight            = w;
+               // c->weight            = bitset_popcnt(c->nodes);
                c->weight_consistent = 1;
        }
 }
@@ -461,15 +515,15 @@ static void aff_chunk_assure_weight(co_mst_env_t *env, aff_chunk_t *c) {
 /**
  * Count the number of interfering affinity neighbours
  */
-static int count_interfering_aff_neighs(co_mst_env_t *env, affinity_node_t *an) {
-       neighb_t     *neigh;
-       ir_node      *irn  = an->irn;
-       co_mst_irn_t *node = get_co_mst_irn(env, irn);
-       int          res   = 0;
+static int count_interfering_aff_neighs(co_mst_env_t *env, const affinity_node_t *an) {
+       const neighb_t     *neigh;
+       const ir_node      *irn  = an->irn;
+       const co_mst_irn_t *node = get_co_mst_irn(env, irn);
+       int                res   = 0;
 
        co_gs_foreach_neighb(an, neigh) {
-               ir_node *n = neigh->irn;
-               int     i;
+               const ir_node *n = neigh->irn;
+               int           i;
 
                /* skip ignore nodes */
                if (arch_irn_is(env->aenv, n, ignore))
@@ -500,7 +554,6 @@ static void build_affinity_chunks(co_mst_env_t *env) {
        ir_node     *n;
        int         i, len;
        aff_chunk_t *curr_chunk;
-       pset_new_iterator_t iter;
 
        /* at first we create the affinity edge objects */
        be_ifg_foreach_node(env->ifg, nodes_it, n) {
@@ -520,9 +573,11 @@ static void build_affinity_chunks(co_mst_env_t *env) {
 
                        if (n1->int_aff_neigh < 0)
                                n1->int_aff_neigh = count_interfering_aff_neighs(env, an);
+
+                       /* build the affinity edges */
                        co_gs_foreach_neighb(an, neigh) {
-                               ir_node *m    = neigh->irn;
-                               int     m_idx = get_irn_idx(m);
+                               const ir_node *m     = neigh->irn;
+                               int            m_idx = get_irn_idx(m);
 
                                /* record the edge in only one direction */
                                if (n_idx < m_idx) {
@@ -541,7 +596,11 @@ static void build_affinity_chunks(co_mst_env_t *env) {
                                                affinity_node_t *am = get_affinity_info(env->co, m);
                                                n2->int_aff_neigh = count_interfering_aff_neighs(env, am);
                                        }
-                                       edge.weight = (double)neigh->costs / (double)(1 + n1->int_aff_neigh + n2->int_aff_neigh);
+                                       /*
+                                        * these weights are pure hackery ;-).
+                                        * It's not chriswue's fault but mine.
+                                        */
+                                       edge.weight = neigh->costs;
                                        ARR_APP1(aff_edge_t, edges, edge);
                                }
                        }
@@ -558,7 +617,7 @@ static void build_affinity_chunks(co_mst_env_t *env) {
        }
 
        /* now insert all chunks into a priority queue */
-       foreach_pset_new(&env->chunkset, curr_chunk, iter) {
+       foreach_pset(env->chunkset, curr_chunk) {
                aff_chunk_assure_weight(env, curr_chunk);
 
                DBG((dbg, LEVEL_1, "entry #%d", curr_chunk->id));
@@ -588,6 +647,71 @@ static void build_affinity_chunks(co_mst_env_t *env) {
        DEL_ARR_F(edges);
 }
 
+static __attribute__((unused)) void chunk_order_nodes(co_mst_env_t *env, aff_chunk_t *chunk)
+{
+       pqueue *grow = new_pqueue();
+       const ir_node *max_node = NULL;
+       int max_weight = 0;
+       int i;
+
+       for (i = ARR_LEN(chunk->n) - 1; i >= 0; i--) {
+               const ir_node   *irn = chunk->n[i];
+               affinity_node_t *an  = get_affinity_info(env->co, irn);
+               int w = 0;
+               neighb_t *neigh;
+
+               if (arch_irn_is(env->aenv, irn, ignore))
+                       continue;
+
+               if (an) {
+                       co_gs_foreach_neighb(an, neigh)
+                               w += neigh->costs;
+
+                       if (w > max_weight) {
+                               max_weight = w;
+                               max_node   = irn;
+                       }
+               }
+       }
+
+       if (max_node) {
+               bitset_t *visited = bitset_irg_malloc(env->co->irg);
+
+               for (i = ARR_LEN(chunk->n) - 1; i >= 0; --i)
+                       bitset_add_irn(visited, chunk->n[i]);
+
+               pqueue_put(grow, (void *) max_node, max_weight);
+               bitset_remv_irn(visited, max_node);
+               i = 0;
+               while (!pqueue_empty(grow)) {
+                       ir_node *irn = pqueue_get(grow);
+                       affinity_node_t *an = get_affinity_info(env->co, irn);
+                       neighb_t *neigh;
+
+                       if (arch_irn_is(env->aenv, irn, ignore))
+                               continue;
+
+                       assert(i <= ARR_LEN(chunk->n));
+                       chunk->n[i++] = irn;
+
+                       assert(an);
+
+                       /* build the affinity edges */
+                       co_gs_foreach_neighb(an, neigh) {
+                               co_mst_irn_t *node = get_co_mst_irn(env, neigh->irn);
+
+                               if (bitset_contains_irn(visited, node->irn)) {
+                                       pqueue_put(grow, (void *) neigh->irn, neigh->costs);
+                                       bitset_remv_irn(visited, node->irn);
+                               }
+                       }
+               }
+
+               del_pqueue(grow);
+               bitset_free(visited);
+       }
+}
+
 /**
  * Greedy collect affinity neighbours into thew new chunk @p chunk starting at node @p node.
  */
@@ -596,7 +720,7 @@ static void expand_chunk_from(co_mst_env_t *env, co_mst_irn_t *node, bitset_t *v
 {
        waitq *nodes = new_waitq();
 
-       DBG((dbg, LEVEL_1, "\nExpanding new chunk (id %d) from %+F:", chunk->id, node->irn));
+       DBG((dbg, LEVEL_1, "\n\tExpanding new chunk (#%d) from %+F, color %d:", chunk->id, node->irn, col));
 
        /* init queue and chunk */
        waitq_put(nodes, node);
@@ -613,8 +737,8 @@ static void expand_chunk_from(co_mst_env_t *env, co_mst_irn_t *node, bitset_t *v
                if (an != NULL) {
                        neighb_t *neigh;
                        co_gs_foreach_neighb(an, neigh) {
-                               ir_node      *m    = neigh->irn;
-                               int          m_idx = get_irn_idx(m);
+                               const ir_node *m    = neigh->irn;
+                               int            m_idx = get_irn_idx(m);
                                co_mst_irn_t *n2;
 
                                /* skip ignore nodes */
@@ -657,29 +781,31 @@ static void expand_chunk_from(co_mst_env_t *env, co_mst_irn_t *node, bitset_t *v
  */
 static aff_chunk_t *fragment_chunk(co_mst_env_t *env, int col, aff_chunk_t *c, waitq *tmp) {
        bitset_t    *visited = bitset_irg_malloc(env->co->irg);
-       int         idx;
+       int         idx, len;
        aff_chunk_t *best = NULL;
 
-       bitset_foreach(c->nodes, idx) {
-               ir_node       *irn;
+       for (idx = 0, len = ARR_LEN(c->n); idx < len; ++idx) {
+               const ir_node *irn;
                co_mst_irn_t  *node;
                aff_chunk_t   *tmp_chunk;
                decide_func_t *decider;
                int           check_for_best;
 
-               if (bitset_is_set(visited, idx))
+               irn = c->n[idx];
+               if (bitset_is_set(visited, get_irn_idx(irn)))
                        continue;
 
-               irn  = get_idx_irn(env->co->irg, idx);
                node = get_co_mst_irn(env, irn);
 
                if (get_mst_irn_col(node) == col) {
                        decider        = decider_has_color;
                        check_for_best = 1;
+                       DBG((dbg, LEVEL_4, "\tcolor %d wanted", col));
                }
                else {
                        decider        = decider_hasnot_color;
                        check_for_best = 0;
+                       DBG((dbg, LEVEL_4, "\tcolor %d forbidden", col));
                }
 
                /* create a new chunk starting at current node */
@@ -700,148 +826,115 @@ static aff_chunk_t *fragment_chunk(co_mst_env_t *env, int col, aff_chunk_t *c, w
 }
 
 /**
- * Initializes an array of color-cost pairs.
- * Sets forbidden colors to costs COL_COST_INFEASIBLE and all others to @p c.
+ * Resets the temporary fixed color of all nodes within wait queue @p nodes.
+ * ATTENTION: the queue is empty after calling this function!
  */
-static INLINE void col_cost_init(co_mst_env_t *env, col_cost_t *cost, double c) {
-       int i;
+static INLINE void reject_coloring(struct list_head *nodes) {
+       co_mst_irn_t *n, *temp;
+       DB((dbg, LEVEL_4, "\treject coloring for"));
+       list_for_each_entry_safe(co_mst_irn_t, n, temp, nodes, list) {
+               DB((dbg, LEVEL_4, " %+F", n->irn));
+               assert(n->tmp_col >= 0);
+               n->tmp_col = -1;
+               list_del_init(&n->list);
+       }
+       DB((dbg, LEVEL_4, "\n"));
+}
 
-       for (i = 0; i < env->n_regs; ++i) {
-               cost[i].col = i;
-               if (bitset_is_set(env->ignore_regs, i))
-                       cost[i].cost = COL_COST_INFEASIBLE;
-               else
-                       cost[i].cost = c;
+static INLINE void materialize_coloring(struct list_head *nodes) {
+       co_mst_irn_t *n, *temp;
+       list_for_each_entry_safe(co_mst_irn_t, n, temp, nodes, list) {
+               assert(n->tmp_col >= 0);
+               n->col     = n->tmp_col;
+               n->tmp_col = -1;
+               list_del_init(&n->list);
        }
 }
 
-/**
- * Initializes an array of color-cost pairs.
- * Sets all colors except color @p col to COL_COST_INFEASIBLE and @p col to 0.0
- */
-static INLINE void col_cost_init_single(co_mst_env_t *env, col_cost_t *cost, int col) {
-       assert(! bitset_is_set(env->ignore_regs, col) && "Attempt to use forbidden color.");
-       col_cost_init(env, cost, COL_COST_INFEASIBLE);
-       cost[col].col = 0;
-       cost[0].col   = col;
-       cost[0].cost  = 0.0;
+static INLINE void set_temp_color(co_mst_irn_t *node, int col, struct list_head *changed)
+{
+       assert(col >= 0);
+       assert(!node->fixed);
+       assert(node->tmp_col < 0);
+       assert(node->list.next == &node->list && node->list.prev == &node->list);
+       assert(bitset_is_set(node->adm_colors, col));
+
+       list_add_tail(&node->list, changed);
+       node->tmp_col = col;
 }
 
-/**
- * Resets the temporary fixed color of all nodes within wait queue @p nodes.
- * ATTENTION: the queue is empty after calling this function!
- */
-static INLINE void reject_coloring(waitq *nodes) {
-       while (! waitq_empty(nodes)) {
-               co_mst_irn_t *n = waitq_get(nodes);
-               n->tmp_fixed = 0;
-       }
+static INLINE int is_loose(co_mst_irn_t *node)
+{
+       return !node->fixed && node->tmp_col < 0;
 }
 
 /**
  * Determines the costs for each color if it would be assigned to node @p node.
  */
 static void determine_color_costs(co_mst_env_t *env, co_mst_irn_t *node, col_cost_t *costs) {
-       affinity_node_t *an = get_affinity_info(env->co, node->irn);
-       neighb_t        *aff_neigh;
-       int             idx, i;
-
-       col_cost_init(env, costs, 0.0);
-
-       /* calculate (negative) costs for affinity neighbours */
-       if (an != NULL) {
-               co_gs_foreach_neighb(an, aff_neigh) {
-                       ir_node      *m = aff_neigh->irn;
-                       co_mst_irn_t *neigh;
-                       double       c;
-
-                       /* skip ignore nodes */
-                       if (arch_irn_is(env->aenv, m, ignore))
-                               continue;
-
-                       neigh = get_co_mst_irn(env, m);
-                       c     = (double)aff_neigh->costs;
+       int *neigh_cols = alloca(env->n_regs * sizeof(*neigh_cols));
+       int n_loose = 0;
+       double coeff;
+       int i;
 
-                       /* calculate costs for fixed affinity neighbours */
-                       if (neigh->tmp_fixed || neigh->fixed) {
-                               int col = get_mst_irn_col(neigh);
-                               costs[col].cost -= c * AFF_NEIGHBOUR_FIX_BENEFIT;
-                       }
-               }
+       for (i = 0; i < env->n_regs; ++i) {
+               neigh_cols[i] = 0;
+               costs[i].col = i;
+               costs[i].cost = bitset_is_set(node->adm_colors, i) ? node->constr_factor : 0.0;
        }
 
-       /* calculate (positive) costs for interfering neighbours */
        for (i = 0; i < node->n_neighs; ++i) {
-               co_mst_irn_t *neigh;
-               int          col, col_cnt;
-               ir_node      *int_neigh;
-
-               int_neigh = node->int_neighs[i];
-
-               /* skip ignore nodes */
-               if (arch_irn_is(env->aenv, int_neigh, ignore))
-                       continue;
-
-               neigh   = get_co_mst_irn(env, int_neigh);
-               col     = get_mst_irn_col(neigh);
-               col_cnt = bitset_popcnt(neigh->adm_colors);
-
-               if (neigh->tmp_fixed || neigh->fixed) {
-                       /* colors of fixed interfering neighbours are infeasible */
-                       costs[col].cost = COL_COST_INFEASIBLE;
-               }
-               else if (col_cnt < env->k) {
-                       /* calculate costs for constrained interfering neighbours */
-                       double ratio = 1.0 - ((double)col_cnt / (double)env->k);
-
-                       bitset_foreach_clear(neigh->adm_colors, idx) {
-                               /* check only explicitly forbidden colors (skip global forbidden ones) */
-                               if (! bitset_is_set(env->ignore_regs, idx)) {
-                                       costs[col].cost += ratio * NEIGHBOUR_CONSTR_COSTS;
-                               }
-                       }
+               co_mst_irn_t *n = get_co_mst_irn(env, node->int_neighs[i]);
+               int col = get_mst_irn_col(n);
+               if (is_loose(n)) {
+                       ++n_loose;
+                       ++neigh_cols[col];
                }
+
+               else
+                       costs[col].cost = 0.0;
        }
 
-       /* set all not admissible colors to COL_COST_INFEASIBLE */
-       bitset_foreach_clear(node->adm_colors, idx)
-               costs[idx].cost = COL_COST_INFEASIBLE;
+       if (n_loose > 0) {
+               coeff = 1.0 / n_loose;
+               for (i = 0; i < env->n_regs; ++i)
+                       costs[i].cost *= 1.0 - coeff * neigh_cols[i];
+       }
 }
 
 /* need forward declaration due to recursive call */
-static int recolor_nodes(co_mst_env_t *env, co_mst_irn_t *node, col_cost_t *costs, waitq *changed_ones);
+static int recolor_nodes(co_mst_env_t *env, co_mst_irn_t *node, col_cost_t *costs, struct list_head *changed_ones, int depth, int *max_depth, int *trip);
 
 /**
  * Tries to change node to a color but @p explude_col.
  * @return 1 if succeeded, 0 otherwise.
  */
-static int change_node_color_excluded(co_mst_env_t *env, co_mst_irn_t *node, int exclude_col, waitq *changed_ones) {
+static int change_node_color_excluded(co_mst_env_t *env, co_mst_irn_t *node, int exclude_col, struct list_head *changed, int depth, int *max_depth, int *trip) {
        int col = get_mst_irn_col(node);
        int res = 0;
 
        /* neighbours has already a different color -> good, temporary fix it */
        if (col != exclude_col) {
-               node->tmp_fixed = 1;
-               node->tmp_col   = col;
-               waitq_put(changed_ones, node);
+               if (is_loose(node))
+                       set_temp_color(node, col, changed);
                return 1;
        }
 
        /* The node has the color it should not have _and_ has not been visited yet. */
-       if (! (node->tmp_fixed || node->fixed)) {
+       if (is_loose(node)) {
                col_cost_t *costs = alloca(env->n_regs * sizeof(costs[0]));
 
                /* Get the costs for giving the node a specific color. */
                determine_color_costs(env, node, costs);
 
                /* Since the node must not have the not_col, set the costs for that color to "infinity" */
-               costs[exclude_col].cost = COL_COST_INFEASIBLE;
+               costs[exclude_col].cost = 0.0;
 
                /* sort the colors according costs, cheapest first. */
-               qsort(costs, env->n_regs, sizeof(costs[0]), cmp_col_cost);
+               qsort(costs, env->n_regs, sizeof(costs[0]), cmp_col_cost_gt);
 
                /* Try recoloring the node using the color list. */
-               res = recolor_nodes(env, node, costs, changed_ones);
+               res = recolor_nodes(env, node, costs, changed, depth + 1, max_depth, trip);
        }
 
        return res;
@@ -852,14 +945,20 @@ static int change_node_color_excluded(co_mst_env_t *env, co_mst_irn_t *node, int
  * ATTENTION: Expect @p costs already sorted by increasing costs.
  * @return 1 if coloring could be applied, 0 otherwise.
  */
-static int recolor_nodes(co_mst_env_t *env, co_mst_irn_t *node, col_cost_t *costs, waitq *changed_ones) {
+static int recolor_nodes(co_mst_env_t *env, co_mst_irn_t *node, col_cost_t *costs, struct list_head *changed, int depth, int *max_depth, int *trip) {
        int   i;
-       waitq *local_changed = new_waitq();
-       waitq *tmp           = new_waitq();
+       struct list_head local_changed;
 
-       DBG((dbg, LEVEL_1, "\tRecoloring %+F with color-costs", node->irn));
-       DBG_COL_COST(env, LEVEL_1, costs);
-       DB((dbg, LEVEL_1, "\n"));
+       ++*trip;
+       if (depth > *max_depth)
+               *max_depth = depth;
+
+       if (depth >= recolor_limit)
+               return 0;
+
+       DBG((dbg, LEVEL_4, "\tRecoloring %+F with color-costs", node->irn));
+       DBG_COL_COST(env, LEVEL_4, costs);
+       DB((dbg, LEVEL_4, "\n"));
 
        for (i = 0; i < env->n_regs; ++i) {
                int tgt_col  = costs[i].col;
@@ -867,20 +966,14 @@ static int recolor_nodes(co_mst_env_t *env, co_mst_irn_t *node, col_cost_t *cost
                int j;
 
                /* If the costs for that color (and all successive) are infinite, bail out we won't make it anyway. */
-               if (costs[i].cost == COL_COST_INFEASIBLE) {
-                       node->tmp_fixed = 0;
-                       del_waitq(local_changed);
-                       del_waitq(tmp);
+               if (costs[i].cost == 0.0)
                        return 0;
-               }
 
                /* Set the new color of the node and mark the node as temporarily fixed. */
-               assert(! node->tmp_fixed && "Node must not have been temporary fixed.");
-               node->tmp_fixed = 1;
-               node->tmp_col   = tgt_col;
-
-               assert(waitq_empty(local_changed) && "Node queue should be empty here.");
-               waitq_put(local_changed, node);
+               assert(node->tmp_col < 0 && "Node must not have been temporary fixed.");
+               INIT_LIST_HEAD(&local_changed);
+               set_temp_color(node, tgt_col, &local_changed);
+               DBG((dbg, LEVEL_4, "\tTemporary setting %+F to color %d\n", node->irn, tgt_col));
 
                /* try to color all interfering neighbours with current color forbidden */
                for (j = 0; j < node->n_neighs; ++j) {
@@ -894,6 +987,8 @@ static int recolor_nodes(co_mst_env_t *env, co_mst_irn_t *node, col_cost_t *cost
                                continue;
 
                        nn = get_co_mst_irn(env, neigh);
+                       DB((dbg, LEVEL_4, "\tHandling neighbour %+F, at position %d (fixed: %d, tmp_col: %d, col: %d)\n",
+                               neigh, j, nn->fixed, nn->tmp_col, nn->col));
 
                        /*
                                Try to change the color of the neighbor and record all nodes which
@@ -903,13 +998,9 @@ static int recolor_nodes(co_mst_env_t *env, co_mst_irn_t *node, col_cost_t *cost
                        */
                        if (get_mst_irn_col(nn) == tgt_col) {
                                /* try to color neighbour with tgt_col forbidden */
-                               neigh_ok = change_node_color_excluded(env, nn, tgt_col, tmp);
-
-                               /* join lists of changed nodes */
-                               while (! waitq_empty(tmp))
-                                       waitq_put(local_changed, waitq_get(tmp));
+                               neigh_ok = change_node_color_excluded(env, nn, tgt_col, &local_changed, depth + 1, max_depth, trip);
 
-                               if (! neigh_ok)
+                               if (!neigh_ok)
                                        break;
                        }
                }
@@ -920,20 +1011,15 @@ static int recolor_nodes(co_mst_env_t *env, co_mst_irn_t *node, col_cost_t *cost
                */
                if (neigh_ok) {
                        /* append the local_changed ones to global ones */
-                       while (! waitq_empty(local_changed))
-                               waitq_put(changed_ones, waitq_get(local_changed));
-                       del_waitq(local_changed);
-                       del_waitq(tmp);
+                       list_splice(&local_changed, changed);
                        return 1;
                }
                else {
                        /* coloring of neighbours failed, so we try next color */
-                       reject_coloring(local_changed);
+                       reject_coloring(&local_changed);
                }
        }
 
-       del_waitq(local_changed);
-       del_waitq(tmp);
        return 0;
 }
 
@@ -941,17 +1027,14 @@ static int recolor_nodes(co_mst_env_t *env, co_mst_irn_t *node, col_cost_t *cost
  * Tries to bring node @p node and all it's neighbours to color @p tgt_col.
  * @return 1 if color @p col could be applied, 0 otherwise
  */
-static int change_node_color(co_mst_env_t *env, co_mst_irn_t *node, int tgt_col, waitq *changed_ones) {
+static int change_node_color(co_mst_env_t *env, co_mst_irn_t *node, int tgt_col, struct list_head *changed) {
        int col = get_mst_irn_col(node);
 
        /* if node already has the target color -> good, temporary fix it */
        if (col == tgt_col) {
                DBG((dbg, LEVEL_4, "\t\tCNC: %+F has already color %d, fix temporary\n", node->irn, tgt_col));
-               if (! node->tmp_fixed) {
-                       node->tmp_fixed = 1;
-                       node->tmp_col   = tgt_col;
-                       waitq_put(changed_ones, node);
-               }
+               if (is_loose(node))
+                       set_temp_color(node, tgt_col, changed);
                return 1;
        }
 
@@ -959,22 +1042,26 @@ static int change_node_color(co_mst_env_t *env, co_mst_irn_t *node, int tgt_col,
                Node has not yet a fixed color and target color is admissible
                -> try to recolor node and it's affinity neighbours
        */
-       if (! (node->fixed || node->tmp_fixed) && bitset_is_set(node->adm_colors, tgt_col)) {
-               col_cost_t *costs = alloca(env->n_regs * sizeof(costs[0]));
-               int        res;
+       if (is_loose(node) && bitset_is_set(node->adm_colors, tgt_col)) {
+               col_cost_t *costs = env->single_cols[tgt_col];
+               int res, max_depth, trip;
 
-               col_cost_init_single(env, costs, tgt_col);
+               max_depth = 0;
+               trip      = 0;
 
                DBG((dbg, LEVEL_4, "\t\tCNC: Attempt to recolor %+F ===>>\n", node->irn));
-               res = recolor_nodes(env, node, costs, changed_ones);
+               res = recolor_nodes(env, node, costs, changed, 0, &max_depth, &trip);
                DBG((dbg, LEVEL_4, "\t\tCNC: <<=== Recoloring of %+F %s\n", node->irn, res ? "succeeded" : "failed"));
+               stat_ev_int("heur4_recolor_depth_max", max_depth);
+               stat_ev_int("heur4_recolor_trip", trip);
+
 
                return res;
        }
 
-       DEBUG_ONLY(
+#ifdef DEBUG_libfirm
                if (firm_dbg_get_mask(dbg) & LEVEL_4) {
-                       if (node->fixed || node->tmp_fixed)
+                       if (!is_loose(node))
                                DB((dbg, LEVEL_4, "\t\tCNC: %+F has already fixed color %d\n", node->irn, col));
                        else {
                                DB((dbg, LEVEL_4, "\t\tCNC: color %d not admissible for %+F (", tgt_col, node->irn));
@@ -982,7 +1069,7 @@ static int change_node_color(co_mst_env_t *env, co_mst_irn_t *node, int tgt_col,
                                DB((dbg, LEVEL_4, ")\n"));
                        }
                }
-       )
+#endif
 
        return 0;
 }
@@ -993,65 +1080,150 @@ static int change_node_color(co_mst_env_t *env, co_mst_irn_t *node, int tgt_col,
  */
 static void color_aff_chunk(co_mst_env_t *env, aff_chunk_t *c) {
        aff_chunk_t *best_chunk   = NULL;
+       int         n_nodes       = ARR_LEN(c->n);
        int         best_color    = -1;
-       waitq       *changed_ones = new_waitq();
+       int         n_int_chunks  = 0;
        waitq       *tmp_chunks   = new_waitq();
+       waitq       *best_starts  = NULL;
+       col_cost_t  *order        = alloca(env->n_regs * sizeof(order[0]));
        bitset_t    *visited;
-       int         col, idx;
+       int         idx, len, i;
+       struct list_head changed;
+       bitset_pos_t pos;
 
        DB((dbg, LEVEL_2, "fragmentizing chunk #%d", c->id));
        DBG_AFF_CHUNK(env, LEVEL_2, c);
        DB((dbg, LEVEL_2, "\n"));
 
+       stat_ev_ctx_push_fmt("heur4_color_chunk", "%d", c->id);
+
+       ++env->chunk_visited;
+
+       /* compute color preference */
+       memset(order, 0, env->n_regs * sizeof(order[0]));
+
+       bitset_foreach (c->interfere, pos) {
+               ir_node      *n    = get_idx_irn(env->co->irg, pos);
+               co_mst_irn_t *node = get_co_mst_irn(env, n);
+               aff_chunk_t *chunk = node->chunk;
+
+               if (is_loose(node) && chunk && chunk->visited < env->chunk_visited && !chunk->deleted) {
+                       chunk->visited = env->chunk_visited;
+                       ++n_int_chunks;
 
-       /* check which color is the "best" for the given chunk */
-       for (col = 0; col < env->k; ++col) {
-               int         reg_col = env->map_regs[col];
-               int         one_good = 0;
+                       aff_chunk_assure_weight(env, chunk);
+                       for (i = 0; i < env->n_regs; ++i)
+                               order[i].cost += chunk->color_affinity[i].cost;
+               }
+       }
+
+       for (i = 0; i < env->n_regs; ++i) {
+               double dislike = n_int_chunks > 0 ? 1.0 - order[i].cost / n_int_chunks : 0.0;
+               order[i].col  = i;
+               order[i].cost = (1.0 - dislike_influence) * c->color_affinity[i].cost + dislike_influence * dislike;
+       }
+
+       qsort(order, env->n_regs, sizeof(order[0]), cmp_col_cost_gt);
+
+       DBG_COL_COST(env, LEVEL_2, order);
+       DB((dbg, LEVEL_2, "\n"));
+
+       /* check which color is the "best" for the given chunk.
+        * if we found a color which was ok for all nodes, we take it
+        * and do not look further. (see did_all flag usage below.)
+        * If we have many colors which fit all nodes it is hard to decide
+        * which one to take anyway.
+        * TODO Sebastian: Perhaps we should at all nodes and figure out
+        * a suitable color using costs as done above (determine_color_costs).
+        */
+       for (i = 0; i < env->k; ++i) {
+               int         col = order[i].col;
+               waitq       *good_starts = new_waitq();
                aff_chunk_t *local_best;
+               int          n_succeeded;
+
+               /* skip ignore colors */
+               if (bitset_is_set(env->ignore_regs, col))
+                       continue;
+
+               DB((dbg, LEVEL_2, "\ttrying color %d\n", col));
 
-               DB((dbg, LEVEL_3, "\ttrying color %d\n", reg_col));
+               n_succeeded = 0;
 
                /* try to bring all nodes of given chunk to the current color. */
-               bitset_foreach(c->nodes, idx) {
-                       ir_node      *irn  = get_idx_irn(env->co->irg, idx);
-                       co_mst_irn_t *node = get_co_mst_irn(env, irn);
+               for (idx = 0, len = ARR_LEN(c->n); idx < len; ++idx) {
+                       const ir_node   *irn  = c->n[idx];
+                       co_mst_irn_t    *node = get_co_mst_irn(env, irn);
+                       int              good;
 
                        assert(! node->fixed && "Node must not have a fixed color.");
+                       DB((dbg, LEVEL_4, "\t\tBringing %+F from color %d to color %d ...\n", irn, node->col, col));
 
-                       DB((dbg, LEVEL_4, "\t\tBringing %+F from color %d to color %d ...\n", irn, node->col, reg_col));
-                       one_good |= change_node_color(env, node, reg_col, changed_ones);
-                       DB((dbg, LEVEL_4, "\t\t... %+F attempt from %d to %d %s\n", irn, node->col, reg_col, one_good ? "succeeded" : "failed"));
+                       /*
+                               The order of the colored nodes is important, so we record the successfully
+                               colored ones in the order they appeared.
+                       */
+                       INIT_LIST_HEAD(&changed);
+                       stat_ev_tim_push();
+                       good = change_node_color(env, node, col, &changed);
+                       stat_ev_tim_pop("heur4_recolor");
+                       if (good) {
+                               waitq_put(good_starts, node);
+                               materialize_coloring(&changed);
+                               node->fixed = 1;
+                       }
+
+                       else
+                               reject_coloring(&changed);
+
+                       n_succeeded += good;
+                       DB((dbg, LEVEL_4, "\t\t... %+F attempt from %d to %d %s\n", irn, node->col, col, good ? "succeeded" : "failed"));
+               }
+
+               /* unfix all nodes */
+               for (idx = 0, len = ARR_LEN(c->n); idx < len; ++idx) {
+                       co_mst_irn_t *node = get_co_mst_irn(env, c->n[idx]);
+                       node->fixed = 0;
                }
 
                /* try next color when failed */
-               if (! one_good)
+               if (n_succeeded == 0)
                        continue;
 
                /* fragment the chunk according to the coloring */
-               local_best = fragment_chunk(env, reg_col, c, tmp_chunks);
+               local_best = fragment_chunk(env, col, c, tmp_chunks);
 
                /* search the best of the good list
                   and make it the new best if it is better than the current */
                if (local_best) {
                        aff_chunk_assure_weight(env, local_best);
 
-                       DB((dbg, LEVEL_4, "\t\tlocal best chunk (id %d) for color %d: ", local_best->id, reg_col));
-                       DBG_AFF_CHUNK(env, LEVEL_4, local_best);
+                       DB((dbg, LEVEL_3, "\t\tlocal best chunk (id %d) for color %d: ", local_best->id, col));
+                       DBG_AFF_CHUNK(env, LEVEL_3, local_best);
 
                        if (! best_chunk || best_chunk->weight < local_best->weight) {
                                best_chunk = local_best;
-                               best_color = reg_col;
-                               DB((dbg, LEVEL_4, "\n\t\t... setting global best chunk (id %d), color %d\n", best_chunk->id, best_color));
+                               best_color = col;
+                               if (best_starts)
+                                       del_waitq(best_starts);
+                               best_starts = good_starts;
+                               DB((dbg, LEVEL_3, "\n\t\t... setting global best chunk (id %d), color %d\n", best_chunk->id, best_color));
                        } else {
-                               DB((dbg, LEVEL_4, "\n\t\t... omitting, global best is better\n"));
+                               DB((dbg, LEVEL_3, "\n\t\t... omitting, global best is better\n"));
+                               del_waitq(good_starts);
                        }
                }
+               else {
+                       del_waitq(good_starts);
+               }
 
-               /* reject the coloring and bring the coloring to the initial state */
-               reject_coloring(changed_ones);
+               /* if all nodes were recolored, bail out */
+               if (n_succeeded == n_nodes)
+                       break;
        }
 
+       stat_ev_int("heur4_colors_tried", i);
+
        /* free all intermediate created chunks except best one */
        while (! waitq_empty(tmp_chunks)) {
                aff_chunk_t *tmp = waitq_get(tmp_chunks);
@@ -1062,7 +1234,8 @@ static void color_aff_chunk(co_mst_env_t *env, aff_chunk_t *c) {
 
        /* return if coloring failed */
        if (! best_chunk) {
-               del_waitq(changed_ones);
+               if (best_starts)
+                       del_waitq(best_starts);
                return;
        }
 
@@ -1070,42 +1243,52 @@ static void color_aff_chunk(co_mst_env_t *env, aff_chunk_t *c) {
        DBG_AFF_CHUNK(env, LEVEL_2, best_chunk);
        DB((dbg, LEVEL_2, "using color %d\n", best_color));
 
-       /* get the best fragment from the best list and color it */
-       bitset_foreach(best_chunk->nodes, idx) {
-               ir_node      *irn  = get_idx_irn(env->co->irg, idx);
-               co_mst_irn_t *node = get_co_mst_irn(env, irn);
-               int          res;
-
-               res = change_node_color(env, node, best_color, changed_ones);
-               assert(res && "color manifesting failed");
-               node->fixed = 1;
-               node->chunk = best_chunk;
-       }
-
-       /* materialize colors on changed nodes */
-       while (! waitq_empty(changed_ones)) {
-               co_mst_irn_t *n = waitq_get(changed_ones);
-               n->tmp_fixed = 0;
-               n->col       = n->tmp_col;
+       for (idx = 0, len = ARR_LEN(best_chunk->n); idx < len; ++idx) {
+               const ir_node *irn  = best_chunk->n[idx];
+               co_mst_irn_t  *node = get_co_mst_irn(env, irn);
+               int res;
+
+               /* bring the node to the color. */
+               DB((dbg, LEVEL_4, "\tManifesting color %d for %+F, chunk #%d\n", best_color, node->irn, best_chunk->id));
+               INIT_LIST_HEAD(&changed);
+               stat_ev_tim_push();
+               res = change_node_color(env, node, best_color, &changed);
+               stat_ev_tim_pop("heur4_recolor");
+               if (res) {
+                       materialize_coloring(&changed);
+                       node->fixed = 1;
+               }
+               assert(list_empty(&changed));
        }
 
        /* remove the nodes in best chunk from original chunk */
        bitset_andnot(c->nodes, best_chunk->nodes);
+       for (idx = 0, len = ARR_LEN(c->n); idx < len; ++idx) {
+               const ir_node *irn = c->n[idx];
+
+               if (bitset_is_set(best_chunk->nodes, get_irn_idx(irn))) {
+                       int last = ARR_LEN(c->n) - 1;
+
+                       c->n[idx] = c->n[last];
+                       ARR_SHRINKLEN(c->n, last);
+                       len--;
+               }
+       }
 
        /* we have to get the nodes back into the original chunk because they are scattered over temporary chunks */
-       bitset_foreach(c->nodes, idx) {
-               ir_node      *n  = get_idx_irn(env->co->irg, idx);
-               co_mst_irn_t *nn = get_co_mst_irn(env, n);
+       for (idx = 0, len = ARR_LEN(c->n); idx < len; ++idx) {
+               const ir_node *n  = c->n[idx];
+               co_mst_irn_t  *nn = get_co_mst_irn(env, n);
                nn->chunk = c;
        }
 
        /* fragment the remaining chunk */
        visited = bitset_irg_malloc(env->co->irg);
        bitset_or(visited, best_chunk->nodes);
-       bitset_foreach(c->nodes, idx) {
-               if (! bitset_is_set(visited, idx)) {
+       for (idx = 0, len = ARR_LEN(c->n); idx < len; ++idx) {
+               const ir_node *irn = c->n[idx];
+               if (! bitset_is_set(visited, get_irn_idx(irn))) {
                        aff_chunk_t  *new_chunk = new_aff_chunk(env);
-                       ir_node      *irn       = get_idx_irn(env->co->irg, idx);
                        co_mst_irn_t *node      = get_co_mst_irn(env, irn);
 
                        expand_chunk_from(env, node, visited, new_chunk, c, decider_always_yes, 0);
@@ -1114,52 +1297,69 @@ static void color_aff_chunk(co_mst_env_t *env, aff_chunk_t *c) {
                }
        }
 
+       for (idx = 0, len = ARR_LEN(best_chunk->n); idx < len; ++idx) {
+               const ir_node *n  = best_chunk->n[idx];
+               co_mst_irn_t  *nn = get_co_mst_irn(env, n);
+               nn->chunk = NULL;
+       }
+
        /* clear obsolete chunks and free some memory */
        delete_aff_chunk(env, best_chunk);
        bitset_free(visited);
-       del_waitq(changed_ones);
+       if (best_starts)
+               del_waitq(best_starts);
+
+       stat_ev_ctx_pop("heur4_color_chunk");
 }
 
 /**
  * Main driver for mst safe coalescing algorithm.
  */
-int co_solve_heuristic_mst(copy_opt_t *co)
-{
+int co_solve_heuristic_mst(copy_opt_t *co) {
        unsigned     n_regs       = co->cls->n_regs;
        bitset_t     *ignore_regs = bitset_alloca(n_regs);
-       unsigned     k, idx, num;
+       unsigned     i, j, k;
        ir_node      *irn;
        co_mst_env_t mst_env;
 
+       stat_ev_tim_push();
+
        /* init phase */
        phase_init(&mst_env.ph, "co_mst", co->irg, PHASE_DEFAULT_GROWTH, co_mst_irn_init, &mst_env);
 
        k = be_put_ignore_regs(co->cenv->birg, co->cls, ignore_regs);
        k = n_regs - k;
 
-       /* Create a color to register number map. In some architectures registers are ignore "in the middle"
-          of the register set. */
-       mst_env.map_regs = NEW_ARR_D(int, phase_obst(&mst_env.ph), k);
-       for (idx = num = 0; idx < n_regs; ++idx) {
-               if (bitset_is_set(ignore_regs, idx))
-                       continue;
-               mst_env.map_regs[num++] = idx;
+       mst_env.n_regs        = n_regs;
+       mst_env.k             = k;
+       mst_env.chunks        = new_pqueue();
+       mst_env.co            = co;
+       mst_env.ignore_regs   = ignore_regs;
+       mst_env.ifg           = co->cenv->ifg;
+       mst_env.aenv          = co->aenv;
+       mst_env.chunkset      = pset_new_ptr(512);
+       mst_env.chunk_visited = 0;
+       mst_env.single_cols   = phase_alloc(&mst_env.ph, sizeof(*mst_env.single_cols) * n_regs);
+
+       for (i = 0; i < n_regs; ++i) {
+               col_cost_t *vec = phase_alloc(&mst_env.ph, sizeof(*vec) * n_regs);
+
+               mst_env.single_cols[i] = vec;
+               for (j = 0; j < n_regs; ++j) {
+                       vec[j].col  = j;
+                       vec[j].cost = 0.0;
+               }
+               vec[i].col  = 0;
+               vec[0].col  = i;
+               vec[0].cost = 1.0;
        }
-       assert(num == k);
-
-       mst_env.n_regs      = n_regs;
-       mst_env.k           = k;
-       mst_env.chunks      = new_pqueue();
-       mst_env.co          = co;
-       mst_env.ignore_regs = ignore_regs;
-       mst_env.ifg         = co->cenv->ifg;
-       mst_env.aenv        = co->aenv;
-       pset_new_init(&mst_env.chunkset);
 
        DBG((dbg, LEVEL_1, "==== Coloring %+F, class %s ====\n", co->irg, co->cls->name));
 
        /* build affinity chunks */
+       stat_ev_tim_push();
        build_affinity_chunks(&mst_env);
+       stat_ev_tim_pop("heur4_initial_chunk");
 
        /* color chunks as long as there are some */
        while (! pqueue_empty(mst_env.chunks)) {
@@ -1178,7 +1378,7 @@ int co_solve_heuristic_mst(copy_opt_t *co)
                if (arch_irn_is(mst_env.aenv, irn, ignore))
                        continue;
 
-               assert(mirn->fixed && "Node should have fixed color");
+               // assert(mirn->fixed && "Node should have fixed color");
 
                /* skip nodes where color hasn't changed */
                if (mirn->init_col == mirn->col)
@@ -1192,13 +1392,30 @@ int co_solve_heuristic_mst(copy_opt_t *co)
        /* free allocated memory */
        del_pqueue(mst_env.chunks);
        phase_free(&mst_env.ph);
-       pset_new_destroy(&mst_env.chunkset);
+       del_pset(mst_env.chunkset);
+
+       stat_ev_tim_pop("heur4_total");
 
        return 0;
 }
 
+static const lc_opt_table_entry_t options[] = {
+       LC_OPT_ENT_INT      ("limit", "limit recoloring",  &recolor_limit),
+       LC_OPT_ENT_DBL      ("di",    "dislike influence", &dislike_influence),
+       LC_OPT_LAST
+};
+
+
 void be_init_copyheur4(void) {
+       lc_opt_entry_t *be_grp = lc_opt_get_grp(firm_opt_get_root(), "be");
+       lc_opt_entry_t *ra_grp = lc_opt_get_grp(be_grp, "ra");
+       lc_opt_entry_t *chordal_grp = lc_opt_get_grp(ra_grp, "chordal");
+       lc_opt_entry_t *co_grp = lc_opt_get_grp(chordal_grp, "co");
+       lc_opt_entry_t *heur4_grp = lc_opt_get_grp(co_grp, "heur4");
+
+       lc_opt_add_table(heur4_grp, options);
        FIRM_DBG_REGISTER(dbg, "firm.be.co.heur4");
 }
 
+
 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_copyheur4);