typo fixed
[libfirm] / ir / be / bespillbelady2.c
index 30898de..b48b8dc 100644 (file)
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 1995-2007 University of Karlsruhe.  All right reserved.
+ * Copyright (C) 1995-2008 University of Karlsruhe.  All right reserved.
  *
  * This file is part of libFirm.
  *
@@ -20,7 +20,7 @@
 /**
  * @file
  * @brief       Beladys spillalgorithm version 2.
- * @author      Daniel Grund, Matthias Braun, Sebastian Hack
+ * @author      Sebastian Hack, Matthias Braun, Daniel Grund
  * @date        01.08.2007
  * @version     $Id$
  *
 #include "ircons_t.h"
 #include "irprintf.h"
 #include "execfreq.h"
+#include "dfs_t.h"
 #include "xmalloc.h"
 
 #include "beutil.h"
 #include "bearch_t.h"
-#include "bespillbelady.h"
 #include "besched_t.h"
 #include "beirgmod.h"
 #include "belive_t.h"
 #include "beloopana.h"
 #include "beirg_t.h"
 #include "bemodule.h"
+#include "bespill.h"
+
+#include "lc_opts.h"
+#include "lc_opts_enum.h"
 
 #define DBG_SPILL     1
 #define DBG_WSETS     2
 #define DBG_WORKSET 128
 #define DBG_GLOBAL  256
 
-#define DEAD UINT_MAX
+#define ALREADY_SPILLED_FACTOR 2
+
+#define DEAD       UINT_MAX
+#define LIVE_END   (DEAD-1)
+#define REMAT_DIST (DEAD-2)
+
+static int already_spilled_factor = 2;
+static int remat_live_range_ext   = 1;
+static int global_pass_enabled    = 1;
+
+static const lc_opt_table_entry_t options[] = {
+       LC_OPT_ENT_INT           ("asf",    "already spilled factor",                             &already_spilled_factor),
+       LC_OPT_ENT_BOOL          ("remat",  "rematerializable ops get infinite long live ranges", &remat_live_range_ext),
+       LC_OPT_ENT_BOOL          ("global", "enable/disable the global pass",                     &global_pass_enabled),
+       LC_OPT_LAST
+};
+
 DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)
 
 /**
@@ -86,11 +106,11 @@ DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)
  */
 typedef struct _loc_t {
   ir_node *irn;        /**< A node. */
-  unsigned time;       /**< A use time (see beuses.h). */
-  unsigned version;    /**< That is used in the global pass below.
-                                                For usage see the comments below.
-                                                In the local belady pass, this is not
-                                                important. */
+  unsigned time;       /**< A use time.
+                                                In the global pass this is used
+                                                as the version number and not as a time.
+                                                Only to save space...
+                                               */
 } loc_t;
 
 typedef struct _workset_t {
@@ -101,19 +121,22 @@ typedef struct _workset_t {
 typedef struct _belady_env_t {
        struct obstack ob;
        ir_graph *irg;
+       const dfs_t *dfs;
        const arch_env_t *arch;
        const arch_register_class_t *cls;
        be_lv_t *lv;
        ir_exec_freq *ef;
 
-       ir_node **blocks;   /**< Array of all blocks. */
-       int n_blocks;       /**< Number of blocks in the graph. */
-       int n_regs;                     /**< number of regs in this reg-class */
-       workset_t *ws;          /**< the main workset used while processing a block. ob-allocated */
-       ir_node *instr;         /**< current instruction */
-       unsigned instr_nr;      /**< current instruction number (relative to block start) */
+       ir_node **blocks;            /**< Array of all blocks. */
+       int n_blocks;                /**< Number of blocks in the graph. */
+       int n_regs;                              /**< number of regs in this reg-class */
+       workset_t *ws;                   /**< the main workset used while processing a block. ob-allocated */
+       ir_node *instr;                  /**< current instruction */
+       int instr_nr;                    /**< current instruction number (relative to block start) */
 
-       spill_env_t *senv;      /**< see bespill.h */
+       spill_env_t *senv;               /**< see bespill.h */
+       bitset_t *spilled;           /**< bitset to keep all the irns which have already been spilled. */
+       ir_nodeset_t *extra_spilled; /** All nodes for which a special spill location has been computed. */
 } belady_env_t;
 
 
@@ -121,7 +144,7 @@ static int loc_compare(const void *a, const void *b)
 {
        const loc_t *p = a;
        const loc_t *q = b;
-       return (int) p->time - (int) q->time;
+       return (p->time > q->time) - (p->time < q->time);
 }
 
 static INLINE void workset_print(const workset_t *w)
@@ -183,7 +206,7 @@ static INLINE void workset_insert(belady_env_t *env, workset_t *ws, ir_node *val
        int i;
        /* check for current regclass */
        if (!arch_irn_consider_in_reg_alloc(env->arch, env->cls, val)) {
-               DBG((dbg, DBG_WORKSET, "Skipped %+F\n", val));
+               // DBG((dbg, DBG_WORKSET, "Skipped %+F\n", val));
                return;
        }
 
@@ -245,40 +268,48 @@ static INLINE int workset_get_index(const workset_t *ws, const ir_node *val) {
 #define workset_sort(ws) qsort((ws)->vals, (ws)->len, sizeof((ws)->vals[0]), loc_compare);
 #define workset_contains(ws, n) (workset_get_index(ws, n) >= 0)
 
+typedef struct _bring_in_t bring_in_t;
+
 typedef struct _block_info_t {
        belady_env_t *bel;
-       const ir_node *bl;
-       workset_t *ws_start, *ws_end;
+       ir_node *bl;
+       int id;
        ir_phase next_uses;
+       workset_t *ws_end;       /**< The end set after the local belady pass. */
+       double exec_freq;        /**< The execution frequency of this block. */
 
+       double reload_cost;      /**< Cost of a reload in this block. */
        ir_node *first_non_in;   /**< First node in block which is not a phi.  */
        ir_node *last_ins;       /**< The instruction before which end of
                                                           block reloads will be inserted. */
 
-       workset_t *entrance_reg; /**< That set will contain all values
-                                                                 transported into the block which
-                                                                 are used before they are displaced.
-                                                                 That means, we later have to care to
-                                                                 bring them into the block in a register
-                                                                 or reload them at the entry of the block. */
+       int pressure;            /**< The amount of registers which remain free
+                                              in this block. This capacity can be used to let
+                                              global variables, transported into other blocks,
+                                              live through this block. */
 
-       int pressure; /**< The amount of registers which remain free
-                                       in this block. This capacity can be used to let
-                                       global variables, transported into other blocks,
-                                       live through this block. */
+       int front_pressure;      /**< The pressure right before the first
+                                                          real (non-phi) node. At the beginning
+                                                          of the global pass, this is 0. */
+       struct list_head br_head; /**< List head for all bring_in variables. */
+       int free_at_jump;         /**< registers free at jump. */
 
-       double exec_freq; /**< The execution frequency of this block. */
 } block_info_t;
 
-static INLINE void *new_block_info(belady_env_t *bel, ir_node *bl) {
+static INLINE void *new_block_info(belady_env_t *bel, int id)
+{
+       ir_node      *bl  = bel->blocks[id];
        block_info_t *res = obstack_alloc(&bel->ob, sizeof(*res));
        memset(res, 0, sizeof(res[0]));
        res->first_non_in = NULL;
        res->last_ins = NULL;
        res->bel = bel;
        res->bl  = bl;
-       res->entrance_reg = new_workset(bel, &bel->ob);
+       res->id  = id;
        res->exec_freq    = get_block_execfreq(bel->ef, bl);
+       res->reload_cost  = bel->arch->reload_cost * res->exec_freq;
+       res->free_at_jump = bel->n_regs;
+       INIT_LIST_HEAD(&res->br_head);
        set_irn_link(bl, res);
        return res;
 }
@@ -299,12 +330,13 @@ typedef struct _next_use_t {
                                                                 in the block. Needed to identify
                                                                 transport in values for the global
                                                                 pass. */
-       int step;                  /**< The time step of the use. */
+       sched_timestep_t step;     /**< The time step of the use. */
+       ir_node *irn;
        struct _next_use_t *next;  /**< The next use int this block
                                                                 or NULL. */
 } next_use_t;
 
-static void *next_use_init(ir_phase *phase, ir_node *irn, void *old)
+static void *next_use_init(ir_phase *phase, const ir_node *irn, void *old)
 {
        (void) phase;
        (void) irn;
@@ -316,9 +348,11 @@ static void build_next_uses(block_info_t *bi)
 {
        ir_node *irn;
 
+       sched_renumber(bi->bl);
+
        phase_init(&bi->next_uses, "next uses", bi->bel->irg, PHASE_DEFAULT_GROWTH, next_use_init, NULL);
        sched_foreach_reverse(bi->bl, irn) {
-               int i, step = sched_get_time_step(irn);
+               int i;
 
                if (is_Phi(irn))
                        break;
@@ -328,13 +362,15 @@ static void build_next_uses(block_info_t *bi)
                        next_use_t *curr = phase_get_irn_data(&bi->next_uses, op);
                        next_use_t *use  = phase_alloc(&bi->next_uses, sizeof(use[0]));
 
-                       assert(step >= 0);
                        use->is_first_use = 1;
-                       use->step         = step;
+                       use->step         = sched_get_time_step(irn);
                        use->next         = curr;
+                       use->irn          = irn;
 
-                       if (curr)
+                       if (curr) {
                                curr->is_first_use = 0;
+                               assert(curr->step >= use->step);
+                       }
 
                        phase_set_irn_data(&bi->next_uses, op, use);
                }
@@ -351,6 +387,151 @@ static INLINE void advance_current_use(block_info_t *bi, const ir_node *irn)
        phase_set_irn_data(&bi->next_uses, irn, use->next);
 }
 
+static __attribute__((unused)) int block_freq_gt(const void *a, const void *b)
+{
+       const ir_node * const *p = a;
+       const ir_node * const *q = b;
+       block_info_t *pi = get_block_info(*p);
+       block_info_t *qi = get_block_info(*q);
+       double diff = qi->exec_freq - pi->exec_freq;
+       return (diff > 0) - (diff < 0);
+}
+
+static int block_freq_dfs_gt(const void *a, const void *b)
+{
+       const ir_node * const *p = a;
+       const ir_node * const *q = b;
+       block_info_t *pi = get_block_info(*p);
+       block_info_t *qi = get_block_info(*q);
+       double diff;
+
+       if ((pi->exec_freq > 1.0 && qi->exec_freq > 1.0)
+                       || (pi->exec_freq <= 1.0 && qi->exec_freq <= 1.0)) {
+
+               const dfs_t *dfs = pi->bel->dfs;
+               int pp = dfs_get_post_num(dfs, pi->bl);
+               int pq = dfs_get_post_num(dfs, qi->bl);
+               return pq - pp;
+       }
+
+       diff = qi->exec_freq - pi->exec_freq;
+       return (diff > 0) - (diff < 0);
+}
+
+/*
+   ____       _               ___
+  | __ ) _ __(_)_ __   __ _  |_ _|_ __
+  |  _ \| '__| | '_ \ / _` |  | || '_ \
+  | |_) | |  | | | | | (_| |  | || | | |
+  |____/|_|  |_|_| |_|\__, | |___|_| |_|
+                      |___/
+
+  Data structures to represent bring in variables.
+*/
+
+struct _bring_in_t {
+       ir_node *irn;              /**< The node to bring in. */
+       block_info_t *bi;          /**< The block to which bring in should happen. */
+       int pressure_so_far;       /**< The maximal pressure till the first use of irn in bl. */
+       ir_node *first_use;        /**< The first user of irn in bl. */
+       sched_timestep_t use_step; /**< Schedule sttep of the first use. */
+
+       int is_remat : 1;          /**< Is rematerializable. */
+       int sect_pressure;         /**< Offset to maximum pressure in block. */
+       struct list_head list;
+       struct list_head sect_list;
+       bring_in_t *sect_head;
+};
+
+static INLINE bring_in_t *new_bring_in(block_info_t *bi, ir_node *irn, const next_use_t *use)
+{
+       bring_in_t *br    = obstack_alloc(&bi->bel->ob, sizeof(br[0]));
+
+       br->irn             = irn;
+       br->bi              = bi;
+       br->first_use       = use->irn;
+       br->use_step        = use->step;
+       br->is_remat        = be_is_rematerializable(bi->bel->senv, irn, use->irn);
+       br->pressure_so_far = bi->pressure;
+       br->sect_pressure   = bi->front_pressure;
+       br->sect_head       = br;
+
+       INIT_LIST_HEAD(&br->list);
+       INIT_LIST_HEAD(&br->sect_list);
+       list_add_tail(&br->list, &bi->br_head);
+       return br;
+}
+
+static int bring_in_cmp(const void *a, const void *b)
+{
+       const bring_in_t *p = *(const bring_in_t * const *) a;
+       const bring_in_t *q = *(const bring_in_t * const *) b;
+       double fp, fq;
+
+       /* if one of both is a remat node, it will be done after the other. */
+       if (p->is_remat != q->is_remat)
+               return p->is_remat - q->is_remat;
+
+       /* in the same block, the one further in the front has to be processed first!
+        * Otherwise the front_pressure 'trick' is not exact. */
+       if (p->bi == q->bi)
+               return p->use_step - q->use_step;
+
+       fp = p->bi->exec_freq;
+       fq = q->bi->exec_freq;
+
+       /* if both have the same frequency, inspect the frequency of the definition */
+       if (fp == fq) {
+               double fdp = get_block_info(get_nodes_block(p->irn))->exec_freq;
+               double fdq = get_block_info(get_nodes_block(q->irn))->exec_freq;
+
+               /* if the defs of both have the same freq, we go for reverse dfs post order. */
+               if (fdp == fdq) {
+                       const dfs_t *dfs = p->bi->bel->dfs;
+                       int pp = dfs_get_post_num(dfs, p->bi->bl);
+                       int pq = dfs_get_post_num(dfs, q->bi->bl);
+                       return pq - pp;
+               }
+
+               return (fdq > fdp) - (fdq < fdp);
+       }
+
+       return (fq > fp) - (fq < fp);
+}
+
+static INLINE unsigned get_curr_distance(block_info_t *bi, const ir_node *irn, int is_usage)
+{
+       belady_env_t *env          = bi->bel;
+       sched_timestep_t curr_step = sched_get_time_step(env->instr);
+       next_use_t *use            = get_current_use(bi, irn);
+       int flags                  = arch_irn_get_flags(env->arch, irn);
+
+       assert(!(flags & arch_irn_flags_ignore));
+
+       /* We have to keep nonspillable nodes in the workingset */
+       if(flags & arch_irn_flags_dont_spill)
+               return 0;
+
+       if (!is_usage && use && use->step == curr_step)
+               use = use->next;
+
+       if (use) {
+               unsigned res  = use->step - curr_step;
+
+               assert(use->step >= curr_step);
+
+               if (res != 0) {
+                       if (remat_live_range_ext && be_is_rematerializable(env->senv, irn, use->irn))
+                               res = REMAT_DIST;
+                       else if (bitset_contains_irn(env->spilled, irn))
+                               res *= already_spilled_factor;
+               }
+
+               return res;
+       }
+
+       return be_is_live_end(env->lv, bi->bl, irn) ? LIVE_END : DEAD;
+}
 
 static INLINE int is_local_phi(const ir_node *bl, const ir_node *irn)
 {
@@ -370,7 +551,7 @@ static INLINE int is_local_phi(const ir_node *bl, const ir_node *irn)
  */
 static INLINE int is_transport_in(const ir_node *bl, const ir_node *irn)
 {
-       return is_local_phi(bl, irn) || get_nodes_block(irn) != bl;
+       return get_nodes_block(irn) != bl || is_Phi(irn);
 }
 
 /**
@@ -398,10 +579,9 @@ static void displace(block_info_t *bi, workset_t *new_vals, int is_usage) {
                /* mark value as used */
 
                if (! workset_contains(ws, val)) {
-                       DBG((dbg, DBG_DECIDE, "    insert %+F\n", val));
+                       DBG((dbg, DBG_DECIDE, "\t\tinsert %+F\n", val));
                        to_insert[demand++] = val;
                        if (is_usage) {
-                               int insert_reload = 1;
                                next_use_t *use = get_current_use(bi, val);
 
                                /*
@@ -411,28 +591,30 @@ static void displace(block_info_t *bi, workset_t *new_vals, int is_usage) {
                                 * entrance to here or not.
                                 */
                                assert(use);
-                               assert(sched_get_time_step(env->instr) == use->step);
+                               assert(sched_get_time_step(env->instr) == (int) use->step);
                                if (is_transport_in(bi->bl, val) && use->is_first_use) {
-                                       DBG((dbg, DBG_DECIDE, "entrance node %+F, pressure %d:\n", val, bi->pressure));
-                                       if (bi->pressure < env->n_regs) {
-                                               workset_insert(env, bi->entrance_reg, val);
-                                               insert_reload = 0;
-                                               ++bi->pressure;
-                                               DBG((dbg, DBG_DECIDE, "... no reload. must be considered at block start\n"));
-                                       }
+                                       bring_in_t *bri = new_bring_in(bi, val, use);
+                                       bri->first_use = env->instr;
+
+                                       /* reset the section pressure, since a new section starts. */
+                                       bi->front_pressure = 0;
+
+                                       DBG((dbg, DBG_DECIDE, "\t\tbring in node %+F, pressure %d:\n", val, bi->pressure));
+                                       DBG((dbg, DBG_DECIDE, "\t\tno reload. must be considered at block start\n"));
                                }
 
-                               if (insert_reload) {
-                                       DBG((dbg, DBG_SPILL, "Reload %+F before %+F\n", val, env->instr));
+                               else {
+                                       bitset_add_irn(env->spilled, val);
+                                       DBG((dbg, DBG_SPILL, "\t\tReload %+F before %+F\n", val, env->instr));
                                        be_add_reload(env->senv, val, env->instr, env->cls, 1);
                                }
                        }
                } else {
-                       assert(is_usage || "Defined value already in workset?!?");
-                       DBG((dbg, DBG_DECIDE, "    skip %+F\n", val));
+                       assert(is_usage && "Defined value already in workset?!?");
+                       DBG((dbg, DBG_DECIDE, "\t\tskip %+F\n", val));
                }
        }
-       DBG((dbg, DBG_DECIDE, "    demand = %d\n", demand));
+       DBG((dbg, DBG_DECIDE, "\t\tdemand = %d\n", demand));
 
        /*
                2. Make room for at least 'demand' slots
@@ -442,20 +624,13 @@ static void displace(block_info_t *bi, workset_t *new_vals, int is_usage) {
 
        /* Only make more free room if we do not have enough */
        if (len > max_allowed) {
-               int curr_step = sched_get_time_step(env->instr);
-
-               DBG((dbg, DBG_DECIDE, "    disposing %d values\n", len - max_allowed));
+               DBG((dbg, DBG_DECIDE, "\t\tdisposing %d values\n", len - max_allowed));
 
                /* get current next-use distance */
                for (i = 0; i < ws->len; ++i) {
-                       ir_node *val = workset_get_val(ws, i);
-                       next_use_t *use = phase_get_irn_data(&bi->next_uses, val);
-                       assert(use == NULL || use->step >= curr_step);
-
-                       if (!is_usage && use)
-                               use = use->next;
-
-                       workset_set_time(ws, i, use ? (unsigned) (use->step - curr_step) : DEAD);
+                       ir_node *val  = workset_get_val(ws, i);
+                       unsigned dist = get_curr_distance(bi, val, is_usage);
+                       workset_set_time(ws, i, dist);
                }
 
                /* sort entries by increasing nextuse-distance*/
@@ -474,8 +649,9 @@ static void displace(block_info_t *bi, workset_t *new_vals, int is_usage) {
        for (i = 0; i < demand; ++i)
                workset_insert(env, env->ws, to_insert[i]);
 
-       bi->pressure = MAX(bi->pressure, workset_get_length(env->ws));
-
+       /* TODO: simplify this expression? */
+       bi->pressure       = MAX(bi->pressure,       workset_get_length(env->ws));
+       bi->front_pressure = MAX(bi->front_pressure, workset_get_length(env->ws));
 }
 
 /**
@@ -483,15 +659,15 @@ static void displace(block_info_t *bi, workset_t *new_vals, int is_usage) {
  * whether it is used from a register or is reloaded
  * before the use.
  */
-static void belady(ir_node *block, void *data) {
-       belady_env_t *env        = data;
-       block_info_t *block_info = new_block_info(env, block);
+static void belady(belady_env_t *env, int id) {
+       block_info_t *block_info = new_block_info(env, id);
+       const ir_node *block     = block_info->bl;
 
        workset_t *new_vals;
        ir_node *irn;
        int iter;
 
-       DBG((dbg, DBG_WSETS, "Processing %+F...\n", block_info->bl));
+       DBG((dbg, DBG_WSETS, "Belady on %+F\n", block_info->bl));
        new_vals = new_workset(env, &env->ob);
        workset_clear(env->ws);
 
@@ -509,11 +685,9 @@ static void belady(ir_node *block, void *data) {
                /* projs are handled with the tuple value.
                 * Phis are no real instr (see insert_starters())
                 * instr_nr does not increase */
-               if (is_Proj(irn) || is_Phi(irn)) {
-                       DBG((dbg, DBG_DECIDE, "  ...%+F skipped\n", irn));
+               if (is_Proj(irn) || is_Phi(irn))
                        continue;
-               }
-               DBG((dbg, DBG_DECIDE, "  ...%+F\n", irn));
+               DBG((dbg, DBG_DECIDE, "\t%+F\n", irn));
 
                if (!block_info->first_non_in)
                        block_info->first_non_in = irn;
@@ -526,6 +700,7 @@ static void belady(ir_node *block, void *data) {
                for(i = 0, arity = get_irn_arity(irn); i < arity; ++i) {
                        workset_insert(env, new_vals, get_irn_n(irn, i));
                }
+               DBG((dbg, DBG_DECIDE, "\t* uses\n"));
                displace(block_info, new_vals, 1);
 
                /*
@@ -557,8 +732,16 @@ static void belady(ir_node *block, void *data) {
                } else {
                        workset_insert(env, new_vals, irn);
                }
+               DBG((dbg, DBG_DECIDE, "\t* defs\n"));
                displace(block_info, new_vals, 0);
 
+               if (is_op_forking(get_irn_op(env->instr))) {
+                       for (i = get_irn_arity(env->instr) - 1; i >= 0; --i) {
+                               ir_node *op = get_irn_n(env->instr, i);
+                               block_info->free_at_jump -= arch_irn_consider_in_reg_alloc(env->arch, env->cls, op);
+                       }
+               }
+
                env->instr_nr++;
        }
 
@@ -570,6 +753,9 @@ static void belady(ir_node *block, void *data) {
        workset_foreach(block_info->ws_end, irn, iter)
                DBG((dbg, DBG_WSETS, "  %+F (%u)\n", irn, workset_get_time(block_info->ws_end, iter)));
        DBG((dbg, DBG_WSETS, "Max pressure in block: %d\n", block_info->pressure));
+
+       /* now, initialize the front pressure to 0. */
+       block_info->front_pressure = 0;
 }
 
 /*
@@ -582,75 +768,140 @@ static void belady(ir_node *block, void *data) {
 
 */
 
-static int block_freq_gt(const void *a, const void *b)
-{
-       const ir_node * const *p = a;
-       const ir_node * const *q = b;
-       block_info_t *pi = get_block_info(*p);
-       block_info_t *qi = get_block_info(*q);
-       double diff = qi->exec_freq - pi->exec_freq;
-       return (diff > 0) - (diff < 0);
-}
+#define workset_set_version(ws, i, t) ((ws)->vals[(i)].time = (t))
+#define workset_get_version(ws, i)    ((ws)->vals[(i)].time)
+
+#define ver_oldest                        (0)
+#define ver_youngest                      ((unsigned) -1)
+#define ver_make_newer(v)                 ((v) + 1)
+#define ver_is_older(v, w)                ((v) < (w))
+#define ver_is_younger(v, w)              ((v) > (w))
+
+enum {
+       irn_act_none = 0,
+       irn_act_reload,
+       irn_act_live_through
+};
+
+typedef struct _block_state_t {
+       struct _block_state_t *next;
+       struct _block_state_t *next_intern;
+       block_info_t *bi;
+       int pressure;
+       workset_t *end_state;
+} block_state_t;
 
-typedef struct _block_end_state_t {
-       ir_node *bl;
+typedef struct _irn_action_t {
+       struct _irn_action_t *next;
        ir_node *irn;
-       double costs;
-       workset_t *end_state;
-       unsigned reload_at_end : 1;
-       unsigned live_through  : 1;
-} block_end_state_t;
+       const ir_node *bl;
+       int act;
+} irn_action_t;
 
 typedef struct _global_end_state_t {
        belady_env_t *env;
        bitset_t *succ_phis;
+       bitset_t *committed;
        struct obstack obst;
-       block_end_state_t *end_info;
-       unsigned gauge;
+       void *reset_level;
        unsigned version;
+
+       unsigned       *bs_tops_vers;
+       block_state_t **bs_tops;
+       block_state_t  *bs_top;
+       irn_action_t   *ia_top;
 } global_end_state_t;
 
-static block_end_state_t *get_block_end_state(global_end_state_t *state, ir_node *bl, ir_node *irn)
+typedef struct {
+       void          *obst_level;
+       block_state_t *bs_top;
+       irn_action_t  *ia_top;
+} rollback_info_t;
+
+static INLINE block_state_t *get_block_state(global_end_state_t *ges, const block_info_t *bi)
 {
-       unsigned i;
+       int id = bi->id;
+       assert(!ver_is_younger(ges->bs_tops_vers[id], ges->version));
+       return ver_is_older(ges->bs_tops_vers[id], ges->version) ? NULL : ges->bs_tops[bi->id];
+}
 
-       for (i = 0; i < state->gauge; ++i) {
-               block_end_state_t *bei = &state->end_info[i];
-               if (bei->bl == bl && bei->irn == irn)
-                       return bei;
+static INLINE const workset_t *get_end_state(global_end_state_t *ges, block_info_t *bi)
+{
+       block_state_t *bs = get_block_state(ges, bi);
+       return bs ? bs->end_state : bi->ws_end;
+}
+
+static block_state_t *new_block_state(global_end_state_t *ges, block_info_t *bi)
+{
+       block_state_t *bs = get_block_state(ges, bi);
+       block_state_t *nw = obstack_alloc(&ges->obst, sizeof(nw[0]));
+
+       nw->next_intern = bs;
+       nw->next        = ges->bs_top;
+       nw->bi          = bi;
+
+       if (bs) {
+               nw->pressure  = bs->pressure;
+               nw->end_state = workset_clone(ges->env, &ges->obst, bs->end_state);
+       }
+       else {
+               nw->pressure  = bi->pressure;
+               nw->end_state = workset_clone(ges->env, &ges->obst, bi->ws_end);
        }
 
-       {
-               block_info_t *bi = get_block_info(bl);
-               block_end_state_t *curr;
+       ges->bs_top               = nw;
+       ges->bs_tops[bi->id]      = nw;
+       ges->bs_tops_vers[bi->id] = ges->version;
+       return nw;
+}
+
+static irn_action_t *new_irn_action(global_end_state_t *ges, ir_node *irn, const ir_node *bl)
+{
+       irn_action_t *ia = obstack_alloc(&ges->obst, sizeof(ia[0]));
+
+       ia->irn  = irn;
+       ia->bl   = bl;
+       ia->act  = irn_act_none;
+       ia->next = ges->ia_top;
+       ges->ia_top = ia;
+       return ia;
+}
 
-               /* make sure we have room in the array */
-               ARR_EXTO(block_end_state_t, state->end_info, (int) state->gauge);
+static INLINE rollback_info_t trans_begin(global_end_state_t *ges)
+{
+       rollback_info_t rb;
+       rb.obst_level = obstack_base(&ges->obst);
+       rb.bs_top     = ges->bs_top;
+       rb.ia_top     = ges->ia_top;
+       return rb;
+}
 
-               curr = &state->end_info[state->gauge];
+static INLINE void trans_rollback(global_end_state_t *ges, rollback_info_t *rb)
+{
+       block_state_t *bs;
 
-               memset(curr, 0, sizeof(curr[0]));
-               curr->bl  = bl;
-               curr->irn = irn;
-               curr->end_state = workset_clone(state->env, &state->obst, bi->ws_end);
-               curr->costs = -1.0;
-               ++state->gauge;
-               return curr;
+       /* unwind all the stacks indiced with the block number */
+       for (bs = ges->bs_top; bs != rb->bs_top; bs = bs->next) {
+               unsigned id = bs->bi->id;
+               ges->bs_tops[id] = bs->next_intern;
        }
+
+       ges->ia_top = rb->ia_top;
+       ges->bs_top = rb->bs_top;
+       obstack_free(&ges->obst, rb->obst_level);
 }
 
-static double can_bring_in(global_end_state_t *ges, ir_node *bl, ir_node *irn, int level);
 
-static double can_make_available_at_end(global_end_state_t *ges, ir_node *bl, ir_node *irn, int level)
+static double can_bring_in(global_end_state_t *ges, ir_node *bl, ir_node *irn, double limit, int level);
+
+static double can_make_available_at_end(global_end_state_t *ges, ir_node *bl, ir_node *irn, double limit, int level)
 {
-       block_end_state_t *bes = get_block_end_state(ges, bl, irn);
-       workset_t *end         = bes->end_state;
-       block_info_t *bi       = get_block_info(bl);
-       int n_regs             = bi->bel->n_regs;
+       block_info_t *bi     = get_block_info(bl);
+       const workset_t *end = get_end_state(ges, bi);
+       double res;
        int index;
 
-       DBG((dbg, DBG_GLOBAL, "\t%2Dcan make avail %+F at end of %+F (pressure %d)\n",
-                               level, irn, bl, bi->pressure));
+       DBG((dbg, DBG_GLOBAL, "\t%2Dcan make avail %+F at end of %+F\n", level, irn, bl));
 
        /*
         * to make the value available at end,
@@ -672,32 +923,27 @@ static double can_make_available_at_end(global_end_state_t *ges, ir_node *bl, ir
         *      cheaper, do the other thing. If not, reload it here.
         */
 
-       /*
-        * we have been here before and already figured out some costs.
-        * so we can exit safely.
-        */
-       if (bes->costs >= 0.0) {
-               DBG((dbg, DBG_GLOBAL, "\t%2Dwe\'ve been here before\n", level));
-               goto end;
-       }
-
        /* if the end set contains it already, it is in a reg and it costs nothing
         * to load it to one. */
        index = workset_get_index(end, irn);
        if (index >= 0) {
-               unsigned ver = end->vals[index].version;
+               unsigned ver = workset_get_version(end, index);
                DBG((dbg, DBG_GLOBAL, "\t%2Dnode is in the end set and is %s fixed\n",
-                                       level, ver > ges->version ? "already" : "not yet"));
+                                       level, ver_is_older(ver, ges->version) ? "already" : "not yet"));
 
                /*
                 * if the version is older, the value is already fixed
-                * and cannot be removed from the end set. If not,
-                * we fix it here by giving it our version.
+                * and cannot be removed from the end set.
+                *
+                * If not, we will create a new block state for that block since
+                * we modify it by giving the end state a new version.
                 */
-               if (ver < ges->version)
-                       end->vals[index].version = ges->version;
+               if (ver_is_younger(ver, ges->version)) {
+                       block_state_t *bs = new_block_state(ges, bi);
+                       workset_set_version(bs->end_state, index, ges->version);
+               }
 
-               bes->costs = 0.0;
+               res = 0.0;
                goto end;
        }
 
@@ -718,26 +964,28 @@ static double can_make_available_at_end(global_end_state_t *ges, ir_node *bl, ir
         */
 
        {
-               int len = workset_get_length(end);
+               int n_regs = bi->free_at_jump;
+               int len  = workset_get_length(end);
                int slot = -1;
                int i;
 
-               bes->costs = HUGE_VAL;
+               res = HUGE_VAL;
 
                /*
                 * look if there is room in the end array
                 * for the variable. Note that this does not
-                * means that the var is living through the block.
+                * mean that the var can live through the block.
                 * There is just room at the *end*
                 */
                if (len < n_regs) {
-                       DBG((dbg, DBG_GLOBAL, "\t%2Dthe end set has %d free slots\n",
-                                               level, n_regs - len));
+                       DBG((dbg, DBG_GLOBAL, "\t%2Dthe end set has %d free slots\n", level, n_regs - len));
                        slot = len;
                } else {
-                       for (i = 0; i < len; ++i)
-                               if (end->vals[i].version < ges->version)
+                       for (i = 0; i < len; ++i) {
+                               unsigned ver = workset_get_version(end, i);
+                               if (ver_is_younger(ver, ges->version))
                                        break;
+                       }
 
                        if (i < len) {
                                DBG((dbg, DBG_GLOBAL, "\t%2D%+F (slot %d) can be erased from the end set\n",
@@ -746,67 +994,104 @@ static double can_make_available_at_end(global_end_state_t *ges, ir_node *bl, ir
                        }
                }
 
+               /*
+                * finally there is some room. we can at least reload the value.
+                * but we will try to let ot live through anyhow.
+                */
                if (slot >= 0) {
-                       int gauge           = ges->gauge;
+                       irn_action_t *vs    = new_irn_action(ges, irn, bi->bl);
+                       block_state_t *bs   = new_block_state(ges, bi);
+                       workset_t *end      = bs->end_state;
                        ir_node *ins_before = block_info_get_last_ins(bi);
                        double reload_here  = be_get_reload_costs(bi->bel->senv, irn, ins_before);
-                       double bring_in     = bi->pressure < n_regs ? can_bring_in(ges, bl, irn, level + 1) : HUGE_VAL;
+                       int pressure_ok     = bs->pressure < n_regs;
 
-                       DBG((dbg, DBG_GLOBAL, "\t%2Dthere is a free slot. capacity=%d, reload here=%f, bring in=%f\n",
-                                               level, n_regs - bi->pressure, reload_here, bring_in));
+                       if (reload_here < bi->reload_cost)
+                               reload_here = 0.0;
 
                        /*
-                        * reloading here pays off; bringing the value in from elsewhere
-                        * is too expensive, hence we drop that search by resetting
-                        * the gauge.
+                        * No matter what we do, the value will be in the end set
+                        * if the block from now on (of course only regarding the
+                        * current state). Enter it and set the new length
+                        * appropriately.
                         */
-                       if (reload_here <= bring_in) {
-                               ges->gauge = gauge;
-                               bes->costs = reload_here;
-                               bes->reload_at_end = 1;
-                       } else {
-                               bes->live_through = 1;
-                               bes->costs = bring_in;
+                       end->vals[slot].irn     = irn;
+                       workset_set_version(end, slot, ges->version);
+                       workset_set_length(end, MAX(workset_get_length(end), slot + 1));
+
+                       vs->act = irn_act_reload;
+                       res     = reload_here;
+
+                       DBG((dbg, DBG_GLOBAL, "\t%2Dthere is a free slot. capacity=%d, reload here=%f, pressure %s\n",
+                                               level, n_regs - bs->pressure, reload_here, pressure_ok ? "ok" : "insufficient"));
+
+
+                       /* look if we can bring the value in. */
+                       if (pressure_ok && reload_here > 0.0) {
+                               rollback_info_t rb = trans_begin(ges);
+                               double new_limit   = MIN(reload_here, limit);
+
+                               vs->act = irn_act_live_through;
+                               bs->pressure += 1;
+                               res = can_bring_in(ges, bl, irn, new_limit, level + 1);
+
+                               /*
+                                * if bring in is too expensive re-adjust the pressure
+                                * and roll back the state
+                                */
+                               if (res >= reload_here) {
+                                       bs->pressure -= 1;
+                                       vs->act = irn_act_reload;
+                                       trans_rollback(ges, &rb);
+                                       res = reload_here;
+                               }
                        }
 
-                       end->vals[slot].irn     = irn;
-                       end->vals[slot].version = ges->version;
-                       end->len = MAX(end->len, slot + 1);
-               } else {
-                       ges->gauge -= 1;
+
+                       DBG((dbg, DBG_GLOBAL, "\t%2D%s\n", level,
+                                               vs->act == irn_act_reload ? "reloading" : "bringing in"));
                }
        }
 
 end:
-       DBG((dbg, DBG_GLOBAL, "\t%2D-> %f\n", level, bes->costs));
-       return bes->costs;
+       DBG((dbg, DBG_GLOBAL, "\t%2D-> %f\n", level, res));
+       return res;
 }
 
-static double can_bring_in(global_end_state_t *ges, ir_node *bl, ir_node *irn, int level)
+static double can_bring_in(global_end_state_t *ges, ir_node *bl, ir_node *irn, double limit, int level)
 {
+       belady_env_t *env = ges->env;
        double glob_costs = HUGE_VAL;
 
-       DBG((dbg, DBG_GLOBAL, "\t%2Dcan bring in for %+F at block %+F\n", level, irn, bl));
+       DBG((dbg, DBG_GLOBAL, "\t%2Dcan bring in (max %f) for %+F at block %+F\n", level, limit, irn, bl));
 
        if (is_transport_in(bl, irn)) {
                int i, n           = get_irn_arity(bl);
                ir_node **nodes    = alloca(get_irn_arity(bl) * sizeof(nodes[0]));
-
-               int gauge_begin    = ges->gauge;
+               rollback_info_t rb = trans_begin(ges);
 
                glob_costs = 0.0;
                for (i = 0; i < n; ++i) {
                        ir_node *pr = get_Block_cfgpred_block(bl, i);
                        ir_node *op = is_local_phi(bl, irn) ? get_irn_n(irn, i) : irn;
-                       double c    = can_make_available_at_end(ges, pr, op, level + 1);
+                       double c;
+
+                       /*
+                        * there might by unknwons as operands of phis in that case
+                        * we set the costs to zero, since they won't get spilled.
+                        */
+                       if (arch_irn_consider_in_reg_alloc(env->arch, env->cls, op))
+                               c = can_make_available_at_end(ges, pr, op, limit - glob_costs, level + 1);
+                       else
+                               c = 0.0;
 
-                       if (c >= HUGE_VAL) {
-                               ges->gauge = gauge_begin;
+                       glob_costs += c;
+
+                       if (glob_costs >= limit) {
                                glob_costs = HUGE_VAL;
+                               trans_rollback(ges, &rb);
                                goto end;
                        }
-
-                       glob_costs += c;
                }
        }
 
@@ -818,135 +1103,337 @@ end:
 static void materialize_and_commit_end_state(global_end_state_t *ges)
 {
        belady_env_t *env = ges->env;
-       unsigned i;
+       irn_action_t *ia;
+       block_state_t *bs;
 
        DBG((dbg, DBG_GLOBAL, "\tmaterializing\n"));
-       for (i = 0; i < ges->gauge; ++i) {
-               block_end_state_t *bes = &ges->end_info[i];
-               block_info_t *bi       = get_block_info(bes->bl);
-               int idx, end_pressure;
-
-               DBG((dbg, DBG_GLOBAL, "\t\t%+F in %+F, cost %f through: %d, rel: %d\n",
-                               bes->irn, bes->bl, bes->costs, bes->live_through, bes->reload_at_end));
-
-               /* insert the reload if the val was reloaded at the block's end */
-               if (bes->reload_at_end) {
-                       be_add_reload_at_end(env->senv, bes->irn, bes->bl, env->cls, 1);
-                       DBG((dbg, DBG_GLOBAL, "\t\tadding reload of %+F at end of %+F\n", bes->irn, bes->bl));
+
+       /*
+        * Perform all the variable actions.
+        */
+       for (ia = ges->ia_top; ia != NULL; ia = ia->next) {
+               switch (ia->act) {
+                       case irn_act_live_through:
+                               {
+                                       block_info_t *bi = get_block_info(ia->bl);
+                                       bring_in_t *iter;
+
+                                       if (is_local_phi(ia->bl, ia->irn)) {
+                                               bitset_add_irn(ges->succ_phis, ia->irn);
+                                               DBG((dbg, DBG_GLOBAL, "\t\tlive through phi kept alive: %+F\n", ia->irn));
+                                       }
+
+                                       list_for_each_entry_reverse(bring_in_t, iter, &bi->br_head, list)
+                                               ++iter->sect_pressure;
+                                       ++bi->front_pressure;
+                               }
+                               break;
+                       case irn_act_reload:
+                               be_add_reload_at_end(env->senv, ia->irn, ia->bl, env->cls, 1);
+                               DBG((dbg, DBG_GLOBAL, "\t\tadding reload of %+F at end of %+F\n", ia->irn, ia->bl));
+                               break;
+                       default:
+                               DBG((dbg, DBG_GLOBAL, "\t\t%+F is in the end set of %+F\n", ia->irn, ia->bl));
                }
+       }
 
-               end_pressure = 0;
-               for (idx = workset_get_length(bes->end_state) - 1; idx >= 0; --idx)
-                       if (bes->end_state->vals[idx].version >= ges->version)
-                               end_pressure += 1;
+       /*
+        * Commit the block end states
+        */
+       for (bs = ges->bs_top; bs != NULL; bs = bs->next) {
+               block_info_t *bi = bs->bi;
+
+               if (!bitset_is_set(ges->committed, bi->id)) {
+                       DBG((dbg, DBG_GLOBAL, "\t\tcommiting workset of %+F with version %x\n", bi->bl, ges->version));
+                       // bes->bs->end_state->vals[idx].version = ges->version;
+                       workset_copy(env, bi->ws_end, bs->end_state);
+                       DBG((dbg, DBG_GLOBAL, "\t\told pressure: %d, new pressure: %d, end length: %d\n",
+                                               bi->pressure, bs->pressure, workset_get_length(bs->end_state)));
+                       bi->pressure = bs->pressure;
+                       bitset_set(ges->committed, bi->id);
+               }
+       }
 
-               /*
-                * if the variable is live through the block,
-                * update the pressure indicator.
-                */
-               DBG((dbg, DBG_GLOBAL, "\t\told pressure %d, ", bi->pressure));
+       /* clear the committed bitset. the next call is expecting it. */
+       bitset_clear_all(ges->committed);
+}
 
-               bi->pressure = MAX(bi->pressure + bes->live_through, end_pressure);
+static ir_node *better_spilled_here(const bring_in_t *br)
+{
+       const block_info_t *bi = br->bi;
+       double spill_ef        = get_block_info(get_nodes_block(br->irn))->exec_freq;
 
-               DBG((dbg, DBG_GLOBAL, "new pressure: %d, end pressure: %d, end length: %d\n",
-                                       bi->pressure, end_pressure, workset_get_length(bes->end_state)));
+       /*
+        * If the bring in node is a phi in the bring in block,
+        * we look at all definitions and sum up their execution frequencies,
+        * since spills will be placed there.
+        * (except for the case where an operand is also a phi which is spilled :-( )
+        * If that cost is higher than spilling the phi in that block, we opt for
+        * bringing the phi into the block and spill it there.
+        */
+       if (is_local_phi(bi->bl, br->irn)) {
+               ir_node *bl = bi->bl;
+               int i;
 
-//             workset_print(bes->end_state);
-               idx = workset_get_index(bes->end_state, bes->irn);
+               spill_ef = 0.0;
+               for (i = get_Block_n_cfgpreds(bl) - 1; i >= 0; --i)
+                       spill_ef += get_block_info(get_Block_cfgpred_block(bl, i))->exec_freq;
+       }
 
-               if (is_local_phi(bes->bl, bes->irn) && bes->live_through)
-                       bitset_add_irn(ges->succ_phis, bes->irn);
+       return bi->exec_freq < spill_ef ? sched_prev(bi->first_non_in) : NULL;
+}
 
-               /*
-                * set the version number in the workset.
-                * That will mark this value as fixed in the end set
-                * and will prevent further investigations from removing
-                * it from there.
-                * Also "commit" the workset;
-                * by copying it back to the block's end workset.
-                */
-               if (idx >= 0) {
-                       DBG((dbg, DBG_GLOBAL, "\t\tcommiting workset of %+F with version %x\n", bes->bl, ges->version));
-                       bes->end_state->vals[idx].version = ges->version;
-                       workset_copy(env, bi->ws_end, bes->end_state);
-               }
+static int get_max_pressure_so_far(const block_info_t *bi, const bring_in_t *br)
+{
+       const struct list_head *l;
+       int res = INT_MIN;
+
+       assert(br->bi == bi);
+       for (l = &br->list; l != &bi->br_head; l = l->prev) {
+               br  = list_entry(l, bring_in_t, list);
+               res = MAX(res, br->sect_pressure);
        }
+
+       /* finally consider the front pressure distance and add the reference line (the global block pressure) */
+       return MAX(res, bi->front_pressure);
 }
 
+#define block_last_bring_in(bi)  list_entry((bi)->br_head.prev, bring_in_t, list)
+
+#if 0
+static int get_block_max_pressure(const block_info_t *bi)
+{
+       int max = get_max_pressure_so_far(bi, block_last_bring_in(bi));
+       return MAX(bi->pressure, max);
+}
+#endif
+
 /**
- * Examine all irns which shall be in regs at the beginning of the
- * block.
+ * Try to bring a variable into a block.
+ * @param ges   The state of all end sets.
+ * @param block The block.
+ * @param irn   The variable.
  */
-static void fix_block_borders(global_end_state_t *ges, ir_node *block) {
-       block_info_t *bi  = get_block_info(block);
-       belady_env_t *env = ges->env;
+static void optimize_variable(global_end_state_t *ges, bring_in_t *br)
+{
+       block_info_t *bi          = br->bi;
+       ir_node *irn              = br->irn;
+       ir_node *bl               = bi->bl;
+       belady_env_t *env         = ges->env;
+       void *reset_level         = obstack_base(&ges->obst);
+       int k                     = env->n_regs;
+       int pressure_upto_use     = get_max_pressure_so_far(bi, br);
+       int front_pressure        = bi->front_pressure;
+       ir_node *better_spill_loc = NULL;
 
-       ir_node *irn;
-       int i;
+       assert(front_pressure <= k);
+       assert(pressure_upto_use <= k);
 
-       DBG((dbg, DBG_GLOBAL, "fixing block borders at %+F (%f)\n", block, bi->exec_freq));
+       DBG((dbg, DBG_GLOBAL, "fixing %+F at %+F (%f), front pr: %d, pr to use: %d, first use: %x\n",
+                               irn, bl, bi->exec_freq, front_pressure, pressure_upto_use, br->first_use));
 
-       /* process all variables which shall be in a reg at
-        * the beginning of the block in the order of the next use. */
-       workset_foreach(bi->entrance_reg, irn, i) {
-               double local_costs = be_get_reload_costs(env->senv, irn, bi->first_non_in);
-               double bring_in_costs;
+       // assert(!is_local_phi(bl, irn) || !bitset_contains_irn(ges->succ_phis, irn));
 
-               /* reset the gauge and create a new version. */
-               ges->gauge    = 0;
-               ges->version -= 1;
+       /*
+        * if we cannot bring the value to the use, let's see ifit would be worthwhile
+        * to bring the value to the beginning of the block to have a better spill
+        * location.
+        *
+        * better _spilled_here will return a node where the value can be spilled after
+        * or NULL if this block does not provide a better spill location.
+        */
+#if 1
+       if (pressure_upto_use >= k && front_pressure < k && !bitset_contains_irn(env->spilled, irn))
+               better_spill_loc = better_spilled_here(br);
+#endif
 
-               DBG((dbg, DBG_GLOBAL, "\ttrans in var %+F, version %x\n", irn, ges->version));
+       /*
+        * If either we can bring the value to the use or we should try
+        * to bring it here to do the spill here, let's try to bring it in.
+        */
+       if (better_spill_loc || pressure_upto_use < k) {
+               block_state_t *bs;
+               double bring_in_costs, local_costs;
+               rollback_info_t trans;
+               int pressure_inc;
+
+               /* process all variables which shall be in a reg at
+                * the beginning of the block in the order of the next use. */
+               local_costs  = be_get_reload_costs(env->senv, irn, br->first_use);
+
+               /* reset the lists */
+               ges->bs_top  = NULL;
+               ges->ia_top  = NULL;
+
+               /* if the variable will live into this block, we must adapt the pressure.
+                * The new pressure is the MAX of:
+                * 1) the total block pressure
+                * 2) the pressure so far + the front pressure increase + 1
+                *
+                * If the second is larger than the first,
+                * we have to increment the total block pressure and hence
+                * save the old pressure to restire it in case of failing to
+                * bring the variable into the block in a register.
+                */
+               trans = trans_begin(ges);
+               bs    = new_block_state(ges, bi);
+               pressure_inc = MAX(bs->pressure, better_spill_loc ? front_pressure : pressure_upto_use + 1);
+               bs->pressure = pressure_inc;
 
-               bring_in_costs = can_bring_in(ges, block, irn, 1);
 
-               DBG((dbg, DBG_GLOBAL, "\tbring in: %f, local: %f", bring_in_costs, local_costs));
+               assert(bi->pressure <= k);
+               DBG((dbg, DBG_GLOBAL, "\ttrans in var %+F, version %x\n", irn, ges->version));
+               bring_in_costs = can_bring_in(ges, bl, irn, local_costs, 1);
+               DBG((dbg, DBG_GLOBAL, "\tbring in: %f, local: %f\n", bring_in_costs, local_costs));
 
                /*
-                * we were not able to let the value arrive
-                * in a register at the entrance of the block
-                * or it is too costly, so we have to do the reload locally
+                * Following cases can now occur:
+                * 1) There is room and costs ok
+                * 2) Cannot bring to use but can spill at begin and costs are ok
+                * 3) neither of both worked.
+                *
+                * following actions can be taken:
+                * a) commit changes
+                * b) mark phi as succeded if node was phi
+                * c) insert reload at use location
+                * d) give a spill location hint
+                *
+                * this is the case/action matrix
+                *   | abcd
+                * --+----------
+                * 1 | XX
+                * 2 | XXXX
+                * 3 |   X
                 */
-               if (bring_in_costs > local_costs) {
 
-                       DBG((dbg, DBG_GLOBAL, " -> do local reload\n"));
-                       be_add_reload(env->senv, irn, bi->first_non_in, env->cls, 1);
-               } else {
+               /* the costs were acceptable... */
+               if (bring_in_costs < local_costs) {
+                       int check = 0;
+                       bring_in_t *iter;
+
                        /*
+                        * case 1 and first part of case 2:
+                        * commit all the changes done. this manifests the bring-in action.
                         * if the transport-in was a phi (that is actually used in block)
-                        * it will no longer remain and we have to spill it completely.
+                        * mark it in the succ_phis set to *not* phi spill it.
                         */
-                       if (is_local_phi(block, irn))
+                       materialize_and_commit_end_state(ges);
+                       if (is_local_phi(bl, irn))
                                bitset_add_irn(ges->succ_phis, irn);
 
-                       DBG((dbg, DBG_GLOBAL, " -> do remote reload\n"));
-                       materialize_and_commit_end_state(ges);
+                       DBG((dbg, DBG_GLOBAL, "\t-> bring it in.", pressure_inc));
+
+                       /* second half of case 2 */
+                       if (pressure_upto_use >= k) {
+                               DBG((dbg, DBG_GLOBAL, "\t-> use blocked. local reload: %+F, try spill at: %+F\n",
+                                                       br->first_use, better_spill_loc));
+                               be_add_reload(env->senv, irn, br->first_use, env->cls, 1);
+                               be_add_spill(env->senv, irn, better_spill_loc);
+                               ir_nodeset_insert(env->extra_spilled, irn);
+                       }
+
+                       /*
+                        * go from the last bring in use to the first and add all the variabled
+                        * which additionally live through the block to their pressure.
+                        * at the point were the actually treated use is, we have to increase
+                        * the pressure by one more as the nrought in value starts to count.
+                        * Finally, adjust the front pressure as well.
+                        */
+                       pressure_inc = 0;
+                       list_for_each_entry_reverse(bring_in_t, iter, &bi->br_head, list) {
+                               if (iter == br)
+                                       pressure_inc += pressure_upto_use < k;
+                               iter->sect_pressure += pressure_inc;
+                               check = MAX(check, iter->sect_pressure);
+                               DBG((dbg, DBG_GLOBAL, "\tinc section pressure of %+F by %d to %d\n", iter->first_use, pressure_inc, iter->sect_pressure));
+                       }
+                       bi->front_pressure += pressure_inc;
+                       assert(MAX(check, bi->front_pressure) <= bi->pressure);
+                       DBG((dbg, DBG_GLOBAL, "\t-> result: p: %d, fp: %d\n", bi->pressure, bi->front_pressure));
+               }
+
+               /* case 3: nothing worked. insert normal reload and rollback. */
+               else {
+                       DBG((dbg, DBG_GLOBAL, "\t-> bring in was too expensive. local reload: %+F\n", br->first_use));
+                       be_add_reload(env->senv, irn, br->first_use, env->cls, 1);
+                       bitset_add_irn(env->spilled, irn);
+                       trans_rollback(ges, &trans);
                }
+       }
 
-               DBG((dbg, DBG_GLOBAL, "\n"));
+       /* there was no opportunity for optimization at all. reload and be sad ...  */
+       else {
+               DBG((dbg, DBG_GLOBAL, "\t-> can\'t do anything but reload before %+F\n", br->first_use));
+               be_add_reload(env->senv, irn, br->first_use, env->cls, 1);
+               bitset_add_irn(env->spilled, irn);
        }
+
+       DBG((dbg, DBG_GLOBAL, "\n"));
+
+       /* reset the obstack and create a new version. */
+       obstack_free(&ges->obst, reset_level);
+       ges->version = ver_make_newer(ges->version);
 }
 
+static bring_in_t **determine_global_order(belady_env_t *env)
+{
+       bring_in_t **res;
+       bring_in_t *elm;
+       int i, n = 0;
+
+       for (i = env->n_blocks - 1; i >= 0; --i) {
+               block_info_t *bi = get_block_info(env->blocks[i]);
+               list_for_each_entry(bring_in_t, elm, &bi->br_head, list) {
+                       obstack_ptr_grow(&env->ob, elm);
+                       n += 1;
+               }
+       }
+
+       obstack_ptr_grow(&env->ob, NULL);
+       res = obstack_finish(&env->ob);
+       qsort(res, n, sizeof(res[0]), bring_in_cmp);
+       return res;
+}
+
+
+
+
 static void global_assign(belady_env_t *env)
 {
+       ir_nodeset_iterator_t iter;
        global_end_state_t ges;
-       int i;
-
-       obstack_init(&ges.obst);
-       ges.gauge     = 0;
-       ges.env       = env;
-       ges.version   = -1;
-       ges.end_info  = NEW_ARR_F(block_end_state_t, env->n_blocks);
-       ges.succ_phis = bitset_irg_obstack_alloc(&env->ob, env->irg);
+       bring_in_t **br;
+       ir_node *irn;
+       int i, j;
 
        /*
         * sort the blocks according to execution frequency.
         * That's not necessary for belady() but for the global pass later on.
         */
-       qsort(env->blocks, env->n_blocks, sizeof(env->blocks[0]), block_freq_gt);
+       qsort(env->blocks, env->n_blocks, sizeof(env->blocks[0]), block_freq_dfs_gt);
+
+       memset(&ges, 0, sizeof(ges));
+       obstack_init(&ges.obst);
+       ges.env          = env;
+       ges.version      = ver_make_newer(ver_oldest);
+       ges.succ_phis    = bitset_irg_obstack_alloc(&ges.obst, env->irg);
+       ges.committed    = bitset_obstack_alloc(&ges.obst, env->n_blocks);
+       ges.bs_tops      = obstack_alloc(&ges.obst, sizeof(ges.bs_tops[0])      * env->n_blocks);
+       ges.bs_tops_vers = obstack_alloc(&ges.obst, sizeof(ges.bs_tops_vers[0]) * env->n_blocks);
+
+       /* invalidate all state stack pointer versions */
+       for (i = 0; i < env->n_blocks; ++i) {
+               block_info_t *bi = get_block_info(env->blocks[i]);
+               ges.bs_tops_vers[i] = ver_oldest;
+
+               /* Set all block end sets entries to the youngest version */
+               for (j = workset_get_length(bi->ws_end) - 1; j >= 0; --j)
+                       workset_set_version(bi->ws_end, j, ver_youngest);
+       }
 
-       for (i = 0; i < env->n_blocks; ++i)
-               fix_block_borders(&ges, env->blocks[i]);
+       /* determine ordeer and optimize them */
+       for (br = determine_global_order(env); *br; ++br)
+               optimize_variable(&ges, *br);
 
        /*
         * Now we spill phis which cannot be kept since they were replaced
@@ -966,6 +1453,9 @@ static void global_assign(belady_env_t *env)
                }
        }
 
+       /* check dominance for specially spilled nodes. */
+       foreach_ir_nodeset (env->extra_spilled, irn, iter)
+               make_spill_locations_dominate_irn(env->senv, irn);
 }
 
 static void collect_blocks(ir_node *bl, void *data)
@@ -975,7 +1465,16 @@ static void collect_blocks(ir_node *bl, void *data)
        obstack_ptr_grow(&env->ob, bl);
 }
 
-void be_spill_belady_spill_env2(be_irg_t *birg, const arch_register_class_t *cls, spill_env_t *spill_env) {
+/**
+ * Do spilling for a register class on a graph using the belady heuristic.
+ * In the transformed graph, the register pressure never exceeds the number
+ * of available registers.
+ *
+ * @param birg  The backend graph
+ * @param cls   The register class to spill
+ */
+void be_spill_belady(be_irg_t *birg, const arch_register_class_t *cls)
+{
        ir_graph *irg = be_get_birg_irg(birg);
        belady_env_t env;
        int i, n_regs;
@@ -989,56 +1488,65 @@ void be_spill_belady_spill_env2(be_irg_t *birg, const arch_register_class_t *cls
 
        /* init belady env */
        obstack_init(&env.ob);
-       env.irg       = irg;
-       env.arch      = birg->main_env->arch_env;
-       env.cls       = cls;
-       env.lv        = be_get_birg_liveness(birg);
-       env.n_regs    = n_regs;
-       env.ws        = new_workset(&env, &env.ob);
-       env.senv      = spill_env ? spill_env : be_new_spill_env(birg);
-       env.ef        = be_get_birg_exec_freq(birg);
-       env.n_blocks  = 0;
+       env.irg        = irg;
+       env.arch       = be_get_birg_arch_env(birg);
+       env.cls        = cls;
+       env.lv         = be_get_birg_liveness(birg);
+       env.dfs        = env.lv->dfs;
+       env.n_regs     = n_regs;
+       env.ws         = new_workset(&env, &env.ob);
+       env.senv       = be_new_spill_env(birg);
+       env.ef         = be_get_birg_exec_freq(birg);
+       env.spilled    = bitset_irg_obstack_alloc(&env.ob, irg);
+       env.extra_spilled = ir_nodeset_new(64);
+       env.n_blocks   = 0;
 
        irg_block_walk_graph(irg, NULL, collect_blocks, &env);
        obstack_ptr_grow(&env.ob, NULL);
        env.blocks = obstack_finish(&env.ob);
 
+       /* renumbering in the blocks gives nicer debug output as number are smaller. */
+#ifdef DEBUG_libfirm
+       for (i = 0; i < env.n_blocks; ++i)
+               sched_renumber(env.blocks[i]);
+#endif
+
        /* Fix high register pressure in blocks with belady algorithm */
        for (i = 0; i < env.n_blocks; ++i)
-               belady(env.blocks[i], &env);
+               belady(&env, i);
 
        global_assign(&env);
 
+       /* check dominance for specially spilled nodes. */
+       {
+               ir_nodeset_iterator_t iter;
+               ir_node *irn;
+
+               foreach_ir_nodeset (env.extra_spilled, irn, iter)
+                       make_spill_locations_dominate_irn(env.senv, irn);
+       }
+
        /* Insert spill/reload nodes into the graph and fix usages */
        be_insert_spills_reloads(env.senv);
 
        /* clean up */
-       if(spill_env == NULL)
-               be_delete_spill_env(env.senv);
+       be_delete_spill_env(env.senv);
+       ir_nodeset_del(env.extra_spilled);
 
        obstack_free(&env.ob, NULL);
 }
 
-
-/**
- * Do spilling for a register class on a graph using the belady heuristic.
- * In the transformed graph, the register pressure never exceeds the number
- * of available registers.
- *
- * @param birg  The backend graph
- * @param cls   The register class to spill
- */
-static void be_spill_belady(be_irg_t *birg, const arch_register_class_t *cls) {
-       be_spill_belady_spill_env2(birg, cls, NULL);
-}
-
-
 void be_init_spillbelady2(void)
 {
+       lc_opt_entry_t *be_grp    = lc_opt_get_grp(firm_opt_get_root(), "be");
+       lc_opt_entry_t *spill_grp = lc_opt_get_grp(be_grp, "spill");
+       lc_opt_entry_t *bel2_grp  = lc_opt_get_grp(spill_grp, "belady2");
+
        static be_spiller_t belady_spiller = {
                be_spill_belady
        };
 
+       lc_opt_add_table(bel2_grp, options);
        be_register_spiller("belady2", &belady_spiller);
        FIRM_DBG_REGISTER(dbg, "firm.be.spill.belady2");
 }