- activated WITH_UNKNOWN
[libfirm] / ir / opt / combo.c
index 676cdbd..19d0b90 100644 (file)
  * @author  Michael Beck
  * @version $Id$
  *
+ * This is a slightly enhanced version of Cliff Clicks combo algorithm
+ * - support for commutative nodes is added, Add(a,b) and Add(b,a) ARE congruent
+ * - supports all Firm direct (by a data edge) identities except Mux
+ *   (Mux can be a 2-input or 1-input identity, only 2-input is implemented yet)
+ * - supports Confirm nodes (handle them like Copies but do NOT remove them)
+ * - let Cmp nodes calculate Top like all othe data nodes: this would let
+ *   Mux nodes to calculate Unknown instead of taking the true result
+ * - let Cond(Top) always select FALSE/default: This is tricky. Nodes are only reavaluated
+ *   IFF the predecessor changed its type. Because nodes are initialized with Top
+ *   this never happens, let all Proj(Cond) be unreachable.
+ *   We avoid this condition by the same way we work around Phi: whenever a Block
+ *   node is placed on the list, place its Cond nodes (and because they are Tuple
+ *   all its Proj-nodes either on the cprop list)
+ *   Especially, this changes the meaning of Click's example:
+ *
+ *   int main() {
+ *     int x;
+ *
+ *     if (x == 2)
+ *       printf("x == 2\n");
+ *     if (x == 3)
+ *       printf("x == 3\n");
+ *   }
+ *
+ *   Would print:
+ *   x == 2
+ *   x == 3
+ *
+ *   using Click's version while is silent with our.
+ * - support for global congruences is implemented but not tested yet
+ *
  * Note further that we use the terminology from Click's work here, which is different
  * in some cases from Firm terminology.  Especially, Click's type is a
  * Firm tarval/entity, nevertheless we call it type here for "maximum compatibility".
  */
-#ifdef HAVE_CONFIG_H
-# include "config.h"
-#endif
+#include "config.h"
 
 #include <assert.h>
 
@@ -48,7 +77,9 @@
 #include "irop.h"
 #include "irouts.h"
 #include "irgmod.h"
+#include "iropt_dbg.h"
 #include "debug.h"
+#include "array_t.h"
 #include "error.h"
 
 #include "tv_t.h"
 #include "irdump.h"
 
 /* define this to check that all type translations are monotone */
-#define VERIFY_MONOTONE
+#undef VERIFY_MONOTONE
 
-#undef NO_FOLLOWER
+/* define this to check the consistency of partitions */
+#define CHECK_PARTITIONS
+
+
+/* allow optimization of non-strict programs */
+#define WITH_UNKNOWN
 
 typedef struct node_t            node_t;
 typedef struct partition_t       partition_t;
@@ -75,6 +111,7 @@ typedef void (*compute_func)(node_t *node);
 struct opcode_key_t {
        ir_opcode   code;   /**< The Firm opcode. */
        ir_mode     *mode;  /**< The mode of all nodes in the partition. */
+       int         arity;  /**< The arity of this opcode (needed for Phi etc. */
        union {
                long      proj;   /**< For Proj nodes, its proj number */
                ir_entity *ent;   /**< For Sel Nodes, its entity */
@@ -123,8 +160,9 @@ struct node_t {
        unsigned        on_cprop:1;     /**< Set, if this node is on the partition.cprop list. */
        unsigned        on_fallen:1;    /**< Set, if this node is on the fallen list. */
        unsigned        is_follower:1;  /**< Set, if this node is a follower. */
-       unsigned        is_flagged:1;   /**< Set, if this node is flagged by step(). */
        unsigned        by_all_const:1; /**< Set, if this node was once evaluated by all constants. */
+       unsigned        flagged:2;      /**< 2 Bits, set if this node was visited by race 1 or 2. */
+       node_t          *cond;          /**< if this is a Block node, points to its Cond if any */
 };
 
 /**
@@ -162,7 +200,8 @@ typedef struct environment_t {
        pmap            *type2id_map;   /**< The type->id map. */
        int             end_idx;        /**< -1 for local and 0 for global congruences. */
        int             lambda_input;   /**< Captured argument for lambda_partition(). */
-       int             modified;       /**< Set, if the graph was modified. */
+       char            modified;       /**< Set, if the graph was modified. */
+       char            commutative;    /**< Set, if commutation nodes should be handled specially. */
 #ifdef DEBUG_libfirm
        partition_t     *dbg_list;      /**< List of all partitions. */
 #endif
@@ -182,11 +221,135 @@ typedef void *(*what_func)(const node_t *node, environment_t *env);
 /** The debug module handle. */
 DEBUG_ONLY(static firm_dbg_module_t *dbg;)
 
+/** The what reason. */
+DEBUG_ONLY(static const char *what_reason;)
+
 /** Next partition number. */
 DEBUG_ONLY(static unsigned part_nr = 0);
 
+/** The tarval returned by Unknown nodes. */
+static tarval *tarval_UNKNOWN;
+
+/* forward */
+static node_t *identity(node_t *node);
+
+#ifdef CHECK_PARTITIONS
+/**
+ * Check a partition.
+ */
+static void check_partition(const partition_t *T) {
+       node_t   *node;
+       unsigned n = 0;
+
+       list_for_each_entry(node_t, node, &T->Leader, node_list) {
+               assert(node->is_follower == 0);
+               assert(node->flagged == 0);
+               assert(node->part == T);
+               ++n;
+       }
+       assert(n == T->n_leader);
+
+       list_for_each_entry(node_t, node, &T->Follower, node_list) {
+               assert(node->is_follower == 1);
+               assert(node->flagged == 0);
+               assert(node->part == T);
+       }
+}  /* check_partition */
+
+/**
+ * check that all leader nodes in the partition have the same opcode.
+ */
+static void check_opcode(const partition_t *Z) {
+       node_t       *node;
+       opcode_key_t key;
+       int          first = 1;
+
+       list_for_each_entry(node_t, node, &Z->Leader, node_list) {
+               ir_node *irn = node->node;
+
+               if (first) {
+                       key.code   = get_irn_opcode(irn);
+                       key.mode   = get_irn_mode(irn);
+                       key.arity  = get_irn_arity(irn);
+                       key.u.proj = 0;
+                       key.u.ent  = NULL;
+
+                       switch (get_irn_opcode(irn)) {
+                       case iro_Proj:
+                               key.u.proj = get_Proj_proj(irn);
+                               break;
+                       case iro_Sel:
+                               key.u.ent = get_Sel_entity(irn);
+                               break;
+                       default:
+                               break;
+                       }
+                       first = 0;
+               } else {
+                       assert(key.code  == get_irn_opcode(irn));
+                       assert(key.mode  == get_irn_mode(irn));
+                       assert(key.arity == get_irn_arity(irn));
+
+                       switch (get_irn_opcode(irn)) {
+                       case iro_Proj:
+                               assert(key.u.proj == get_Proj_proj(irn));
+                               break;
+                       case iro_Sel:
+                               assert(key.u.ent == get_Sel_entity(irn));
+                               break;
+                       default:
+                               break;
+                       }
+               }
+       }
+}  /* check_opcode */
+
+static void check_all_partitions(environment_t *env) {
 #ifdef DEBUG_libfirm
-static INLINE lattice_elem_t get_partition_type(const partition_t *X);
+       partition_t *P;
+       node_t      *node;
+
+       for (P = env->dbg_list; P != NULL; P = P->dbg_next) {
+               check_partition(P);
+               if (! P->type_is_T_or_C)
+                       check_opcode(P);
+               list_for_each_entry(node_t, node, &P->Follower, node_list) {
+                       node_t *leader = identity(node);
+
+                       assert(leader != node && leader->part == node->part);
+               }
+       }
+#endif
+}
+
+/**
+ * Check list.
+ */
+static void do_check_list(const node_t *list, int ofs, const partition_t *Z) {
+       const node_t *e;
+
+#define NEXT(e)  *((const node_t **)((char *)(e) + (ofs)))
+       for (e = list; e != NULL; e = NEXT(e)) {
+               assert(e->part == Z);
+       }
+#undef NEXT
+}  /* ido_check_list */
+
+/**
+ * Check a local list.
+ */
+static void check_list(const node_t *list, const partition_t *Z) {
+       do_check_list(list, offsetof(node_t, next), Z);
+}  /* check_list */
+
+#else
+#define check_partition(T)
+#define check_list(list, Z)
+#define check_all_partitions(env)
+#endif /* CHECK_PARTITIONS */
+
+#ifdef DEBUG_libfirm
+static inline lattice_elem_t get_partition_type(const partition_t *X);
 
 /**
  * Dump partition to output.
@@ -231,21 +394,21 @@ static void do_dump_list(const char *msg, const node_t *node, int ofs) {
        DB((dbg, LEVEL_3, "\n}\n"));
 
 #undef GET_LINK
-}
+}  /* do_dump_list */
 
 /**
  * Dumps a race list.
  */
 static void dump_race_list(const char *msg, const node_t *list) {
        do_dump_list(msg, list, offsetof(node_t, race_next));
-}
+}  /* dump_race_list */
 
 /**
  * Dumps a local list.
  */
 static void dump_list(const char *msg, const node_t *list) {
        do_dump_list(msg, list, offsetof(node_t, next));
-}
+}  /* dump_list */
 
 /**
  * Dump all partitions.
@@ -256,13 +419,37 @@ static void dump_all_partitions(const environment_t *env) {
        DB((dbg, LEVEL_2, "All partitions\n===============\n"));
        for (P = env->dbg_list; P != NULL; P = P->dbg_next)
                dump_partition("", P);
-}
+}  /* dump_all_partitions */
+
+/**
+ * Sump a split list.
+ */
+static void dump_split_list(const partition_t *list) {
+       const partition_t *p;
+
+       DB((dbg, LEVEL_2, "Split by %s produced = {\n", what_reason));
+       for (p = list; p != NULL; p = p->split_next)
+               DB((dbg, LEVEL_2, "part%u, ", p->nr));
+       DB((dbg, LEVEL_2, "\n}\n"));
+}  /* dump_split_list */
+
+/**
+ * Dump partition and type for a node.
+ */
+static int dump_partition_hook(FILE *F, ir_node *n, ir_node *local) {
+       ir_node *irn = local != NULL ? local : n;
+       node_t *node = get_irn_node(irn);
+
+       ir_fprintf(F, "info2 : \"partition %u type %+F\"\n", node->part->nr, node->type);
+       return 1;
+}  /* dump_partition_hook */
 
 #else
 #define dump_partition(msg, part)
 #define dump_race_list(msg, list)
 #define dump_list(msg, list)
 #define dump_all_partitions(env)
+#define dump_split_list(list)
 #endif
 
 #if defined(VERIFY_MONOTONE) && defined (DEBUG_libfirm)
@@ -286,7 +473,7 @@ static void verify_type(const lattice_elem_t old_type, const lattice_elem_t new_
                return;
        }
        panic("verify_type(): wrong translation from %+F to %+F", old_type, new_type);
-}
+}  /* verify_type */
 #else
 #define verify_type(old_type, new_type)
 #endif
@@ -327,7 +514,7 @@ static void listmap_term(listmap_t *map) {
  * @param map  the listmap
  * @param id   the id to search for
  *
- * @return the asociated listmap entry for the given id
+ * @return the associated listmap entry for the given id
  */
 static listmap_entry_t *listmap_find(listmap_t *map, void *id) {
        listmap_entry_t key, *entry;
@@ -353,7 +540,7 @@ static listmap_entry_t *listmap_find(listmap_t *map, void *id) {
  * @return a hash value for the given opcode map entry
  */
 static unsigned opcode_hash(const opcode_key_t *entry) {
-       return (entry->mode - (ir_mode *)0) * 9 + entry->code + entry->u.proj * 3 + HASH_PTR(entry->u.ent);
+       return (entry->mode - (ir_mode *)0) * 9 + entry->code + entry->u.proj * 3 + HASH_PTR(entry->u.ent) + entry->arity;
 }  /* opcode_hash */
 
 /**
@@ -365,6 +552,7 @@ static int cmp_opcode(const void *elt, const void *key, size_t size) {
 
        (void) size;
        return o1->code != o2->code || o1->mode != o2->mode ||
+              o1->arity != o2->arity ||
               o1->u.proj != o2->u.proj || o1->u.ent != o2->u.ent;
 }  /* cmp_opcode */
 
@@ -399,7 +587,7 @@ static void sort_irn_outs(node_t *node) {
  *
  * @return the associated type of this node
  */
-static INLINE lattice_elem_t get_node_type(const ir_node *irn) {
+static inline lattice_elem_t get_node_type(const ir_node *irn) {
        return get_irn_node(irn)->type;
 }  /* get_node_type */
 
@@ -410,7 +598,7 @@ static INLINE lattice_elem_t get_node_type(const ir_node *irn) {
  *
  * @return the associated type of this node
  */
-static INLINE tarval *get_node_tarval(const ir_node *irn) {
+static inline tarval *get_node_tarval(const ir_node *irn) {
        lattice_elem_t type = get_node_type(irn);
 
        if (is_tarval(type.tv))
@@ -421,8 +609,9 @@ static INLINE tarval *get_node_tarval(const ir_node *irn) {
 /**
  * Add a partition to the worklist.
  */
-static INLINE void add_to_worklist(partition_t *X, environment_t *env) {
+static inline void add_to_worklist(partition_t *X, environment_t *env) {
        assert(X->on_worklist == 0);
+       DB((dbg, LEVEL_2, "Adding part%d to worklist\n", X->nr));
        X->wl_next     = env->worklist;
        X->on_worklist = 1;
        env->worklist  = X;
@@ -435,7 +624,7 @@ static INLINE void add_to_worklist(partition_t *X, environment_t *env) {
  *
  * @return a newly allocated partition
  */
-static INLINE partition_t *new_partition(environment_t *env) {
+static inline partition_t *new_partition(environment_t *env) {
        partition_t *part = obstack_alloc(&env->obst, sizeof(*part));
 
        INIT_LIST_HEAD(&part->Leader);
@@ -465,9 +654,9 @@ static INLINE partition_t *new_partition(environment_t *env) {
 /**
  * Get the first node from a partition.
  */
-static INLINE node_t *get_first_node(const partition_t *X) {
+static inline node_t *get_first_node(const partition_t *X) {
        return list_entry(X->Leader.next, node_t, node_list);
-}
+}  /* get_first_node */
 
 /**
  * Return the type of a partition (assuming partition is non-empty and
@@ -477,7 +666,7 @@ static INLINE node_t *get_first_node(const partition_t *X) {
  *
  * @return the type of the first element of the partition
  */
-static INLINE lattice_elem_t get_partition_type(const partition_t *X) {
+static inline lattice_elem_t get_partition_type(const partition_t *X) {
        const node_t *first = get_first_node(X);
        return first->type;
 }  /* get_partition_type */
@@ -510,8 +699,9 @@ static node_t *create_partition_node(ir_node *irn, partition_t *part, environmen
        node->on_cprop       = 0;
        node->on_fallen      = 0;
        node->is_follower    = 0;
-       node->is_flagged     = 0;
        node->by_all_const   = 0;
+       node->flagged        = 0;
+       node->cond           = NULL;
        set_irn_node(irn, node);
 
        list_add_tail(&node->node_list, &part->Leader);
@@ -529,7 +719,7 @@ static void init_block_phis(ir_node *irn, void *env) {
        if (is_Block(irn)) {
                set_Block_phis(irn, NULL);
        }
-}
+}  /* init_block_phis */
 
 /**
  * Post-Walker, initialize all Nodes' type to U or top and place
@@ -547,29 +737,22 @@ static void create_initial_partitions(ir_node *irn, void *ctx) {
 
        if (is_Phi(irn)) {
                add_Block_phi(get_nodes_block(irn), irn);
-       }
-}  /* create_initial_partitions */
+       } else if (is_Cond(irn)) {
+               node_t *block = get_irn_node(get_nodes_block(irn));
 
-/**
- * Add a partition to the touched set if not already there.
- *
- * @param part  the partition
- * @param env   the environment
- */
-static INLINE void add_to_touched(partition_t *part, environment_t *env) {
-       if (part->on_touched == 0) {
-               part->touched_next = env->touched;
-               env->touched       = part;
-               part->on_touched   = 1;
+               /* link every block with its Cond node if any */
+               block->cond = node;
        }
-}  /* add_to_touched */
+}  /* create_initial_partitions */
 
 /**
- * Add a node to the entry.partition.touched set if not already there.
+ * Add a node to the entry.partition.touched set and
+ * node->partition to the touched set if not already there.
  *
- * @param y  a node
+ * @param y    a node
+ * @param env  the environment
  */
-static INLINE void add_to_partition_touched(node_t *y) {
+static inline void add_to_touched(node_t *y, environment_t *env) {
        if (y->on_touched == 0) {
                partition_t *part = y->part;
 
@@ -577,8 +760,64 @@ static INLINE void add_to_partition_touched(node_t *y) {
                part->touched = y;
                y->on_touched = 1;
                ++part->n_touched;
+
+               if (part->on_touched == 0) {
+                       part->touched_next = env->touched;
+                       env->touched       = part;
+                       part->on_touched   = 1;
+               }
+
+               check_list(part->touched, part);
+       }
+}  /* add_to_touched */
+
+/**
+ * Place a node on the cprop list.
+ *
+ * @param y    the node
+ * @param env  the environment
+ */
+static void add_to_cprop(node_t *y, environment_t *env) {
+       /* Add y to y.partition.cprop. */
+       if (y->on_cprop == 0) {
+               partition_t *Y = y->part;
+
+               list_add_tail(&y->cprop_list, &Y->cprop);
+               y->on_cprop   = 1;
+
+               DB((dbg, LEVEL_3, "Add %+F to part%u.cprop\n", y->node, Y->nr));
+
+               /* place its partition on the cprop list */
+               if (Y->on_cprop == 0) {
+                       Y->cprop_next = env->cprop;
+                       env->cprop    = Y;
+                       Y->on_cprop   = 1;
+               }
+       }
+       if (get_irn_mode(y->node) == mode_T) {
+               /* mode_T nodes always produce tarval_bottom, so we must explicitly
+                  add it's Proj's to get constant evaluation to work */
+               int i;
+
+               for (i = get_irn_n_outs(y->node) - 1; i >= 0; --i) {
+                       node_t *proj = get_irn_node(get_irn_out(y->node, i));
+
+                       add_to_cprop(proj, env);
+               }
+       } else if (is_Block(y->node)) {
+               /* Due to the way we handle Phi's, we must place all Phis of a block on the list
+                * if someone placed the block. The Block is only placed if the reachability
+                * changes, and this must be re-evaluated in compute_Phi(). */
+               ir_node *phi;
+               for (phi = get_Block_phis(y->node); phi != NULL; phi = get_Phi_next(phi)) {
+                       node_t *p = get_irn_node(phi);
+                       add_to_cprop(p, env);
+               }
+               /* same for Conds: they must be re-evaluated due to the way we handle Top */
+               if (y->cond != NULL)
+                       add_to_cprop(y->cond, env);
        }
-}  /* add_to_partition_touched */
+}  /* add_to_cprop */
 
 /**
  * Update the worklist: If Z is on worklist then add Z' to worklist.
@@ -596,48 +835,92 @@ static void update_worklist(partition_t *Z, partition_t *Z_prime, environment_t
        }
 }  /* update_worklist */
 
-#ifdef NO_FOLLOWER
 /**
- * Split a partition by a local list.
+ * Make all inputs to x no longer be F.def_use edges.
  *
- * @param Z    the Z partition to split
+ * @param x  the node
+ */
+static void move_edges_to_leader(node_t *x) {
+       ir_node     *irn = x->node;
+       int         i, j, k;
+
+       for (i = get_irn_arity(irn) - 1; i >= 0; --i) {
+               node_t  *pred = get_irn_node(get_irn_n(irn, i));
+               ir_node *p;
+               int     n;
+
+               p = pred->node;
+               n = get_irn_n_outs(p);
+               for (j = 1; j <= pred->n_followers; ++j) {
+                       if (p->out[j].pos == i && p->out[j].use == irn) {
+                               /* found a follower edge to x, move it to the Leader */
+                               ir_def_use_edge edge = p->out[j];
+
+                               /* remove this edge from the Follower set */
+                               p->out[j] = p->out[pred->n_followers];
+                               --pred->n_followers;
+
+                               /* sort it into the leader set */
+                               for (k = pred->n_followers + 2; k <= n; ++k) {
+                                       if (p->out[k].pos >= edge.pos)
+                                               break;
+                                       p->out[k - 1] = p->out[k];
+                               }
+                               /* place the new edge here */
+                               p->out[k - 1] = edge;
+
+                               /* edge found and moved */
+                               break;
+                       }
+               }
+       }
+}  /* move_edges_to_leader */
+
+/**
+ * Split a partition that has NO followers by a local list.
+ *
+ * @param Z    partition to split
  * @param g    a (non-empty) node list
  * @param env  the environment
  *
  * @return  a new partition containing the nodes of g
  */
-static partition_t *split(partition_t *Z, node_t *g, environment_t *env) {
+static partition_t *split_no_followers(partition_t *Z, node_t *g, environment_t *env) {
        partition_t *Z_prime;
        node_t      *node;
        unsigned    n = 0;
        int         max_input;
 
        dump_partition("Splitting ", Z);
+       dump_list("by list ", g);
 
        assert(g != NULL);
 
        /* Remove g from Z. */
        for (node = g; node != NULL; node = node->next) {
+               assert(node->part == Z);
                list_del(&node->node_list);
                ++n;
        }
        assert(n < Z->n_leader);
        Z->n_leader -= n;
 
-       /* Move g to a new partition, Z\92. */
+       /* Move g to a new partition, Z'. */
        Z_prime = new_partition(env);
        max_input = 0;
        for (node = g; node != NULL; node = node->next) {
-               list_add(&node->node_list, &Z_prime->Leader);
+               list_add_tail(&node->node_list, &Z_prime->Leader);
                node->part = Z_prime;
                if (node->max_user_input > max_input)
                        max_input = node->max_user_input;
        }
        Z_prime->max_user_inputs = max_input;
-       Z_prime->n_leader       = n;
+       Z_prime->n_leader        = n;
+
+       check_partition(Z);
+       check_partition(Z_prime);
 
-       /* for now, copy the type info tag. it will be adjusted
-          in split_by(). */
+       /* for now, copy the type info tag, it will be adjusted in split_by(). */
        Z_prime->type_is_T_or_C = Z->type_is_T_or_C;
 
        update_worklist(Z, Z_prime, env);
@@ -645,22 +928,104 @@ static partition_t *split(partition_t *Z, node_t *g, environment_t *env) {
        dump_partition("Now ", Z);
        dump_partition("Created new ", Z_prime);
        return Z_prime;
-}  /* split */
+}  /* split_no_followers */
 
-#else
+/**
+ * Make the Follower -> Leader transition for a node.
+ *
+ * @param n  the node
+ */
+static void follower_to_leader(node_t *n) {
+       assert(n->is_follower == 1);
+
+       DB((dbg, LEVEL_2, "%+F make the follower -> leader transition\n", n->node));
+       n->is_follower = 0;
+       move_edges_to_leader(n);
+       list_del(&n->node_list);
+       list_add_tail(&n->node_list, &n->part->Leader);
+       ++n->part->n_leader;
+}  /* follower_to_leader */
 
 /**
  * The environment for one race step.
  */
 typedef struct step_env {
-       node_t *initial;       /**< The initial node list. */
-       node_t *unwalked;      /**< The unwalked node list. */
-       node_t *unwalked_last; /**< Points to the last element of the unwalked node list. */
-       node_t *walked;        /**< The walked node list. */
-       int    index;          /**< Next index of Follower use_def edge. */
-       int    n_leader;       /**< number of Leader in initial. */
+       node_t   *initial;    /**< The initial node list. */
+       node_t   *unwalked;   /**< The unwalked node list. */
+       node_t   *walked;     /**< The walked node list. */
+       int      index;       /**< Next index of Follower use_def edge. */
+       unsigned side;        /**< side number. */
 } step_env;
 
+/**
+ * Return non-zero, if a input is a real follower
+ *
+ * @param irn    the node to check
+ * @param input  number of the input
+ */
+static int is_real_follower(const ir_node *irn, int input) {
+       node_t *pred;
+
+       switch (get_irn_opcode(irn)) {
+       case iro_Confirm:
+               if (input == 1) {
+                       /* ignore the Confirm bound input */
+                       return 0;
+               }
+               break;
+       case iro_Mux:
+               if (input == 0) {
+                       /* ignore the Mux sel input */
+                       return 0;
+               }
+               break;
+       case iro_Phi: {
+               /* dead inputs are not follower edges */
+               ir_node *block = get_nodes_block(irn);
+               node_t  *pred  = get_irn_node(get_Block_cfgpred(block, input));
+
+               if (pred->type.tv == tarval_unreachable)
+                       return 0;
+               break;
+       }
+       case iro_Sub:
+       case iro_Shr:
+       case iro_Shl:
+       case iro_Shrs:
+       case iro_Rotl:
+               if (input == 1) {
+                       /* only a Sub x,0 / Shift x,0 might be a follower */
+                       return 0;
+               }
+               break;
+       case iro_Add:
+       case iro_Or:
+       case iro_Eor:
+               pred = get_irn_node(get_irn_n(irn, input));
+               if (is_tarval(pred->type.tv) && tarval_is_null(pred->type.tv))
+                       return 0;
+               break;
+       case iro_Mul:
+               pred = get_irn_node(get_irn_n(irn, input));
+               if (is_tarval(pred->type.tv) && tarval_is_one(pred->type.tv))
+                       return 0;
+               break;
+       case iro_And:
+               pred = get_irn_node(get_irn_n(irn, input));
+               if (is_tarval(pred->type.tv) && tarval_is_all_one(pred->type.tv))
+                       return 0;
+               break;
+       case iro_Min:
+       case iro_Max:
+               /* all inputs are followers */
+               return 1;
+       default:
+               assert(!"opcode not implemented yet");
+               break;
+       }
+       return 1;
+}  /* is_real_follower */
+
 /**
  * Do one step in the race.
  */
@@ -669,11 +1034,8 @@ static int step(step_env *env) {
 
        if (env->initial != NULL) {
                /* Move node from initial to unwalked */
-               n = env->initial;
-               env->initial = n->race_next;
-
-               if (env->unwalked_last == NULL)
-                       env->unwalked_last = n;
+               n             = env->initial;
+               env->initial  = n->race_next;
 
                n->race_next  = env->unwalked;
                env->unwalked = n;
@@ -685,28 +1047,38 @@ static int step(step_env *env) {
                /* let n be the first node in unwalked */
                n = env->unwalked;
                while (env->index < n->n_followers) {
+                       const ir_def_use_edge *edge = &n->node->out[1 + env->index];
+
                        /* let m be n.F.def_use[index] */
-                       node_t *m = get_irn_node(n->node->out[1 + env->index].use);
+                       node_t *m = get_irn_node(edge->use);
 
                        assert(m->is_follower);
+                       /*
+                        * Some inputs, like the get_Confirm_bound are NOT
+                        * real followers, sort them out.
+                        */
+                       if (! is_real_follower(m->node, edge->pos)) {
+                               ++env->index;
+                               continue;
+                       }
                        ++env->index;
 
                        /* only followers from our partition */
                        if (m->part != n->part)
                                continue;
 
-                       if (! m->is_flagged) {
-                               m->is_flagged = 1;
+                       if ((m->flagged & env->side) == 0) {
+                               m->flagged |= env->side;
 
-                               /* add m to unwalked not as first node */
-                               m->race_next = NULL;
-                               if (env->unwalked == NULL) {
-                                       env->unwalked = m;
-                               } else {
-                                       env->unwalked_last->race_next = m;
+                               if (m->flagged != 3) {
+                                       /* visited the first time */
+                                       /* add m to unwalked not as first node (we might still need to
+                                          check for more follower node */
+                                       m->race_next = n->race_next;
+                                       n->race_next = m;
+                                       return 0;
                                }
-                               env->unwalked_last = m;
-                               return 0;
+                               /* else already visited by the other side and on the other list */
                        }
                }
                /* move n to walked */
@@ -719,32 +1091,53 @@ static int step(step_env *env) {
 }  /* step */
 
 /**
- * Clear the flags from a list.
+ * Clear the flags from a list and check for
+ * nodes that where touched from both sides.
  *
  * @param list  the list
  */
-static void clear_flags(node_t *list) {
+static int clear_flags(node_t *list) {
+       int    res = 0;
        node_t *n;
 
-       for (n = list; n != NULL; n = n->race_next)
-               n->is_flagged = 0;
+       for (n = list; n != NULL; n = n->race_next) {
+               if (n->flagged == 3) {
+                       /* we reach a follower from both sides, this will split congruent
+                        * inputs and make it a leader. */
+                       follower_to_leader(n);
+                       res = 1;
+               }
+               n->flagged = 0;
+       }
+       return res;
 }  /* clear_flags */
 
 /**
  * Split a partition by a local list using the race.
  *
- * @param X    the partition to split
+ * @param pX   pointer to the partition to split, might be changed!
  * @param gg   a (non-empty) node list
  * @param env  the environment
  *
  * @return  a new partition containing the nodes of gg
  */
-static partition_t *split(partition_t *X, node_t *gg, environment_t *env) {
+static partition_t *split(partition_t **pX, node_t *gg, environment_t *env) {
+       partition_t *X = *pX;
        partition_t *X_prime;
        list_head   tmp;
-       step_env    env1, env2, *winner;
-       node_t      *g, *h, *node;
-       int         max_input, n, m;
+       step_env    senv[2];
+       node_t      *g, *h, *node, *t;
+       int         max_input, transitions, winner, shf;
+       unsigned    n;
+       DEBUG_ONLY(static int run = 0;)
+
+       DB((dbg, LEVEL_2, "Run %d ", run++));
+       if (list_empty(&X->Follower)) {
+               /* if the partition has NO follower, we can use the fast
+                  splitting algorithm. */
+               return split_no_followers(X, gg, env);
+       }
+       /* else do the race */
 
        dump_partition("Splitting ", X);
        dump_list("by list ", gg);
@@ -753,89 +1146,145 @@ static partition_t *split(partition_t *X, node_t *gg, environment_t *env) {
 
        /* Remove gg from X.Leader and put into g */
        g = NULL;
-       n = 0;
        for (node = gg; node != NULL; node = node->next) {
+               assert(node->part == X);
+               assert(node->is_follower == 0);
+
                list_del(&node->node_list);
                list_add_tail(&node->node_list, &tmp);
                node->race_next = g;
                g               = node;
-               ++n;
        }
        /* produce h */
        h = NULL;
-       m = 0;
        list_for_each_entry(node_t, node, &X->Leader, node_list) {
                node->race_next = h;
                h               = node;
-               ++m;
        }
        /* restore X.Leader */
        list_splice(&tmp, &X->Leader);
 
-       env1.initial       = g;
-       env1.unwalked      = NULL;
-       env1.unwalked_last = NULL;
-       env1.walked        = NULL;
-       env1.index         = 0;
-       env1.n_leader      = n;
-
-       env2.initial       = h;
-       env2.unwalked      = NULL;
-       env2.unwalked_last = NULL;
-       env2.walked        = NULL;
-       env2.index         = 0;
-       env2.n_leader      = m;
-
+       senv[0].initial   = g;
+       senv[0].unwalked  = NULL;
+       senv[0].walked    = NULL;
+       senv[0].index     = 0;
+       senv[0].side      = 1;
+
+       senv[1].initial   = h;
+       senv[1].unwalked  = NULL;
+       senv[1].walked    = NULL;
+       senv[1].index     = 0;
+       senv[1].side      = 2;
+
+       /*
+        * Some informations on the race that are not stated clearly in Click's
+        * thesis.
+        * 1) A follower stays on the side that reach him first.
+        * 2) If the other side reches a follower, if will be converted to
+        *    a leader. /This must be done after the race is over, else the
+        *    edges we are iterating on are renumbered./
+        * 3) /New leader might end up on both sides./
+        * 4) /If one side ends up with new Leaders, we must ensure that
+        *    they can split out by opcode, hence we have to put _every_
+        *    partition with new Leader nodes on the cprop list, as
+        *    opcode splitting is done by split_by() at the end of
+        *    constant propagation./
+        */
        for (;;) {
-               if (step(&env1)) {
-                       winner = &env1;
+               if (step(&senv[0])) {
+                       winner = 0;
                        break;
                }
-               if (step(&env2)) {
-                       winner = &env2;
+               if (step(&senv[1])) {
+                       winner = 1;
                        break;
                }
        }
-       assert(winner->initial == NULL);
-       assert(winner->unwalked == NULL);
+       assert(senv[winner].initial == NULL);
+       assert(senv[winner].unwalked == NULL);
 
        /* clear flags from walked/unwalked */
-       clear_flags(env1.unwalked);
-       clear_flags(env1.walked);
-       clear_flags(env2.unwalked);
-       clear_flags(env2.walked);
+       shf = winner;
+       transitions  = clear_flags(senv[0].unwalked) << shf;
+       transitions |= clear_flags(senv[0].walked)   << shf;
+       shf ^= 1;
+       transitions |= clear_flags(senv[1].unwalked) << shf;
+       transitions |= clear_flags(senv[1].walked)   << shf;
 
-       dump_race_list("winner ", winner->walked);
+       dump_race_list("winner ", senv[winner].walked);
 
-       /* Move walked_{winner} to a new partition, X\92. */
-       X_prime = new_partition(env);
+       /* Move walked_{winner} to a new partition, X'. */
+       X_prime   = new_partition(env);
        max_input = 0;
-       for (node = winner->walked; node != NULL; node = node->race_next) {
+       n         = 0;
+       for (node = senv[winner].walked; node != NULL; node = node->race_next) {
                list_del(&node->node_list);
+               node->part = X_prime;
                if (node->is_follower) {
-                       list_add(&node->node_list, &X_prime->Follower);
+                       list_add_tail(&node->node_list, &X_prime->Follower);
                } else {
-                       list_add(&node->node_list, &X_prime->Leader);
-                       ++X_prime->n_leader;
+                       list_add_tail(&node->node_list, &X_prime->Leader);
+                       ++n;
                }
-               node->part = X_prime;
                if (node->max_user_input > max_input)
                        max_input = node->max_user_input;
        }
+       X_prime->n_leader        = n;
        X_prime->max_user_inputs = max_input;
-       X->n_leader             -= winner->n_leader;
+       X->n_leader             -= X_prime->n_leader;
 
-       /* for now, copy the type info tag. it will be adjusted
-          in split_by(). */
+       /* for now, copy the type info tag, it will be adjusted in split_by(). */
        X_prime->type_is_T_or_C = X->type_is_T_or_C;
 
-       update_worklist(X, X_prime, env);
+       /*
+        * Even if a follower was not checked by both sides, it might have
+        * loose its congruence, so we need to check this case for all follower.
+        */
+       list_for_each_entry_safe(node_t, node, t, &X_prime->Follower, node_list) {
+               if (identity(node) == node) {
+                       follower_to_leader(node);
+                       transitions |= 1;
+               }
+       }
+
+       check_partition(X);
+       check_partition(X_prime);
+
+       /* X' is the smaller part */
+       add_to_worklist(X_prime, env);
+
+       /*
+        * If there where follower to leader transitions, ensure that the nodes
+        * can be split out if necessary.
+        */
+       if (transitions & 1) {
+               /* place winner partition on the cprop list */
+               if (X_prime->on_cprop == 0) {
+                       X_prime->cprop_next = env->cprop;
+                       env->cprop          = X_prime;
+                       X_prime->on_cprop   = 1;
+               }
+       }
+       if (transitions & 2) {
+               /* place other partition on the cprop list */
+               if (X->on_cprop == 0) {
+                       X->cprop_next = env->cprop;
+                       env->cprop    = X;
+                       X->on_cprop   = 1;
+               }
+       }
 
        dump_partition("Now ", X);
        dump_partition("Created new ", X_prime);
+
+       /* we have to ensure that the partition containing g is returned */
+       if (winner != 0) {
+               *pX = X_prime;
+               return X;
+       }
+
        return X_prime;
 }  /* split */
-#endif /* NO_FOLLOWER */
 
 /**
  * Returns non-zero if the i'th input of a Phi node is live.
@@ -866,53 +1315,6 @@ static int is_constant_type(lattice_elem_t type) {
        return 0;
 }  /* is_constant_type */
 
-/**
- * Place a node on the cprop list.
- *
- * @param y    the node
- * @param env  the environment
- */
-static void add_node_to_cprop(node_t *y, environment_t *env) {
-       /* Add y to y.partition.cprop. */
-       if (y->on_cprop == 0) {
-               partition_t *Y = y->part;
-
-               list_add_tail(&y->cprop_list, &Y->cprop);
-               y->on_cprop   = 1;
-
-               DB((dbg, LEVEL_3, "Add %+F to part%u.cprop\n", y->node, Y->nr));
-
-               /* place its partition on the cprop list */
-               if (Y->on_cprop == 0) {
-                       Y->cprop_next = env->cprop;
-                       env->cprop    = Y;
-                       Y->on_cprop   = 1;
-               }
-       }
-       if (get_irn_mode(y->node) == mode_T) {
-               /* mode_T nodes always produce tarval_bottom, so we must explicitly
-                  add it's Proj's to get constant evaluation to work */
-               int i;
-
-               for (i = get_irn_n_outs(y->node) - 1; i >= 0; --i) {
-                       node_t *proj = get_irn_node(get_irn_out(y->node, i));
-
-                       add_node_to_cprop(proj, env);
-               }
-       }
-
-       if (is_Block(y->node)) {
-               /* Due to the way we handle Phi's, we must place all Phis of a block on the list
-                * if someone placed the block. The Block is only placed if the reachability
-                * changes, and this must be re-evaluated in compute_Phi(). */
-               ir_node *phi;
-               for (phi = get_Block_phis(y->node); phi != NULL; phi = get_Phi_next(phi)) {
-                       node_t *p = get_irn_node(phi);
-                       add_node_to_cprop(p, env);
-               }
-       }
-}  /* add_node_to_cprop */
-
 /**
  * Check whether a type is neither Top or a constant.
  * Note: U is handled like Top here, R is a constant.
@@ -930,7 +1332,7 @@ static int type_is_neither_top_nor_const(const lattice_elem_t type) {
                return 0;
        }
        return 1;
-}
+}  /* type_is_neither_top_nor_const */
 
 /**
  * Collect nodes to the touched list.
@@ -948,14 +1350,14 @@ static void collect_touched(list_head *list, int idx, environment_t *env) {
 
                if (idx == -1) {
                        /* leader edges start AFTER follower edges */
-                       x->next_edge = 1 + x->n_followers;
+                       x->next_edge = x->n_followers + 1;
                }
                num_edges = get_irn_n_outs(x->node);
 
                /* for all edges in x.L.def_use_{idx} */
                while (x->next_edge <= num_edges) {
-                       ir_def_use_edge *edge = &x->node->out[x->next_edge];
-                       ir_node         *succ;
+                       const ir_def_use_edge *edge = &x->node->out[x->next_edge];
+                       ir_node               *succ;
 
                        /* check if we have necessary edges */
                        if (edge->pos > idx)
@@ -965,37 +1367,97 @@ static void collect_touched(list_head *list, int idx, environment_t *env) {
 
                        succ = edge->use;
 
+                       /* only non-commutative nodes */
+                       if (env->commutative &&
+                           (idx == 0 || idx == 1) && is_op_commutative(get_irn_op(succ)))
+                               continue;
+
                        /* ignore the "control input" for non-pinned nodes
                        if we are running in GCSE mode */
                        if (idx < end_idx && get_irn_pinned(succ) != op_pin_state_pinned)
                                continue;
 
                        y = get_irn_node(succ);
+                       assert(get_irn_n(succ, idx) == x->node);
+
+                       /* ignore block edges touching followers */
+                       if (idx == -1 && y->is_follower)
+                               continue;
+
                        if (is_constant_type(y->type)) {
                                ir_opcode code = get_irn_opcode(succ);
                                if (code == iro_Sub || code == iro_Cmp)
-                                       add_node_to_cprop(y, env);
+                                       add_to_cprop(y, env);
                        }
 
                        /* Partitions of constants should not be split simply because their Nodes have unequal
-                       functions or incongruent inputs. */
+                          functions or incongruent inputs. */
                        if (type_is_neither_top_nor_const(y->type) &&
                                (! is_Phi(y->node) || is_live_input(y->node, idx))) {
-                                       partition_t *Y = y->part;
-                                       add_to_touched(Y, env);
-                                       add_to_partition_touched(y);
+                                       add_to_touched(y, env);
                        }
                }
        }
-}
+}  /* collect_touched */
+
+/**
+ * Collect commutative nodes to the touched list.
+ *
+ * @param list  the list which contains the nodes that must be evaluated
+ * @param env   the environment
+ */
+static void collect_commutative_touched(list_head *list, environment_t *env) {
+       node_t  *x, *y;
+
+       list_for_each_entry(node_t, x, list, node_list) {
+               int num_edges;
+
+               num_edges = get_irn_n_outs(x->node);
+
+               x->next_edge = x->n_followers + 1;
+
+               /* for all edges in x.L.def_use_{idx} */
+               while (x->next_edge <= num_edges) {
+                       const ir_def_use_edge *edge = &x->node->out[x->next_edge];
+                       ir_node               *succ;
+
+                       /* check if we have necessary edges */
+                       if (edge->pos > 1)
+                               break;
+
+                       ++x->next_edge;
+                       if (edge->pos < 0)
+                               continue;
+
+                       succ = edge->use;
+
+                       /* only commutative nodes */
+                       if (!is_op_commutative(get_irn_op(succ)))
+                               continue;
+
+                       y = get_irn_node(succ);
+                       if (is_constant_type(y->type)) {
+                               ir_opcode code = get_irn_opcode(succ);
+                               if (code == iro_Eor)
+                                       add_to_cprop(y, env);
+                       }
+
+                       /* Partitions of constants should not be split simply because their Nodes have unequal
+                          functions or incongruent inputs. */
+                       if (type_is_neither_top_nor_const(y->type)) {
+                               add_to_touched(y, env);
+                       }
+               }
+       }
+}  /* collect_commutative_touched */
+
 /**
  * Split the partitions if caused by the first entry on the worklist.
  *
  * @param env  the environment
  */
 static void cause_splits(environment_t *env) {
-       partition_t *X, *Z;
-       node_t      *e;
+       partition_t *X, *Z, *N;
        int         idx;
 
        /* remove the first partition from the worklist */
@@ -1005,6 +1467,44 @@ static void cause_splits(environment_t *env) {
 
        dump_partition("Cause_split: ", X);
 
+       if (env->commutative) {
+               /* handle commutative nodes first */
+
+               /* empty the touched set: already done, just clear the list */
+               env->touched = NULL;
+
+               collect_commutative_touched(&X->Leader, env);
+               collect_commutative_touched(&X->Follower, env);
+
+               for (Z = env->touched; Z != NULL; Z = N) {
+                       node_t   *e;
+                       node_t   *touched  = Z->touched;
+                       unsigned n_touched = Z->n_touched;
+
+                       assert(Z->touched != NULL);
+
+                       /* beware, split might change Z */
+                       N = Z->touched_next;
+
+                       /* remove it from the touched set */
+                       Z->on_touched = 0;
+
+                       /* Empty local Z.touched. */
+                       for (e = touched; e != NULL; e = e->next) {
+                               assert(e->is_follower == 0);
+                               e->on_touched = 0;
+                       }
+                       Z->touched   = NULL;
+                       Z->n_touched = 0;
+
+                       if (0 < n_touched && n_touched < Z->n_leader) {
+                               DB((dbg, LEVEL_2, "Split part%d by touched\n", Z->nr));
+                               split(&Z, touched, env);
+                       } else
+                               assert(n_touched <= Z->n_leader);
+               }
+       }
+
        /* combine temporary leader and follower list */
        for (idx = -1; idx <= X->max_user_inputs; ++idx) {
                /* empty the touched set: already done, just clear the list */
@@ -1013,20 +1513,32 @@ static void cause_splits(environment_t *env) {
                collect_touched(&X->Leader, idx, env);
                collect_touched(&X->Follower, idx, env);
 
-               for (Z = env->touched; Z != NULL; Z = Z->touched_next) {
+               for (Z = env->touched; Z != NULL; Z = N) {
+                       node_t   *e;
+                       node_t   *touched  = Z->touched;
+                       unsigned n_touched = Z->n_touched;
+
+                       assert(Z->touched != NULL);
+
+                       /* beware, split might change Z */
+                       N = Z->touched_next;
+
                        /* remove it from the touched set */
                        Z->on_touched = 0;
 
-                       if (Z->n_leader != Z->n_touched) {
-                               DB((dbg, LEVEL_2, "Split part%d by touched\n", Z->nr));
-                               split(Z, Z->touched, env);
-                       }
                        /* Empty local Z.touched. */
-                       for (e = Z->touched; e != NULL; e = e->next) {
+                       for (e = touched; e != NULL; e = e->next) {
+                               assert(e->is_follower == 0);
                                e->on_touched = 0;
                        }
                        Z->touched   = NULL;
                        Z->n_touched = 0;
+
+                       if (0 < n_touched && n_touched < Z->n_leader) {
+                               DB((dbg, LEVEL_2, "Split part%d by touched\n", Z->nr));
+                               split(&Z, touched, env);
+                       } else
+                               assert(n_touched <= Z->n_leader);
                }
        }
 }  /* cause_splits */
@@ -1075,8 +1587,8 @@ static partition_t *split_by_what(partition_t *X, what_func What,
                S = iter->list;
 
                /* Add SPLIT( X, S ) to P. */
-               DB((dbg, LEVEL_2, "Split part%d by what\n", X->nr));
-               R = split(X, S, env);
+               DB((dbg, LEVEL_2, "Split part%d by WHAT = %s\n", X->nr, what_reason));
+               R = split(&X, S, env);
                R->split_next = *P;
                *P            = R;
        }
@@ -1101,6 +1613,7 @@ static void *lambda_opcode(const node_t *node, environment_t *env) {
 
        key.code   = get_irn_opcode(irn);
        key.mode   = get_irn_mode(irn);
+       key.arity  = get_irn_arity(irn);
        key.u.proj = 0;
        key.u.ent  = NULL;
 
@@ -1127,7 +1640,13 @@ static void *lambda_partition(const node_t *node, environment_t *env) {
        int     i = env->lambda_input;
 
        if (i >= get_irn_arity(node->node)) {
-               /* we are outside the allowed range */
+               /*
+                * We are outside the allowed range: This can happen even
+                * if we have split by opcode first: doing so might move Followers
+                * to Leaders and those will have a different opcode!
+                * Note that in this case the partition is on the cprop list and will be
+                * split again.
+                */
                return NULL;
        }
 
@@ -1142,8 +1661,61 @@ static void *lambda_partition(const node_t *node, environment_t *env) {
        return p->part;
 }  /* lambda_partition */
 
+/** lambda n.(n[i].partition) for commutative nodes */
+static void *lambda_commutative_partition(const node_t *node, environment_t *env) {
+       ir_node     *irn     = node->node;
+       ir_node     *skipped = skip_Proj(irn);
+       ir_node     *pred, *left, *right;
+       node_t      *p;
+       partition_t *pl, *pr;
+       int         i = env->lambda_input;
+
+       if (i >= get_irn_arity(node->node)) {
+               /*
+                * We are outside the allowed range: This can happen even
+                * if we have split by opcode first: doing so might move Followers
+                * to Leaders and those will have a different opcode!
+                * Note that in this case the partition is on the cprop list and will be
+                * split again.
+                */
+               return NULL;
+       }
+
+       /* ignore the "control input" for non-pinned nodes
+          if we are running in GCSE mode */
+       if (i < env->end_idx && get_irn_pinned(skipped) != op_pin_state_pinned)
+               return NULL;
+
+       if (i == -1) {
+               pred = get_irn_n(skipped, i);
+               p    = get_irn_node(pred);
+               return p->part;
+       }
+
+       if (is_op_commutative(get_irn_op(irn))) {
+               /* normalize partition order by returning the "smaller" on input 0,
+                  the "bigger" on input 1. */
+               left  = get_binop_left(irn);
+               pl    = get_irn_node(left)->part;
+               right = get_binop_right(irn);
+               pr    = get_irn_node(right)->part;
+
+               if (i == 0)
+                       return pl < pr ? pl : pr;
+               else
+               return pl > pr ? pl : pr;
+       } else {
+               /* a not split out Follower */
+               pred = get_irn_n(irn, i);
+               p    = get_irn_node(pred);
+
+               return p->part;
+       }
+}  /* lambda_commutative_partition */
+
 /**
- * Returns true if a type is a constant.
+ * Returns true if a type is a constant (and NOT Top
+ * or Bottom).
  */
 static int is_con(const lattice_elem_t type) {
        /* be conservative */
@@ -1171,8 +1743,9 @@ static void split_by(partition_t *X, environment_t *env) {
                return;
        }
 
-       DB((dbg, LEVEL_2, "WHAT = lambda n.(n.type) on part%d\n", X->nr));
+       DEBUG_ONLY(what_reason = "lambda n.(n.type)";)
        P = split_by_what(X, lambda_type, &P, env);
+       dump_split_list(P);
 
        /* adjust the type tags, we have split partitions by type */
        for (I = P; I != NULL; I = I->split_next) {
@@ -1189,8 +1762,9 @@ static void split_by(partition_t *X, environment_t *env) {
                        if (! Y->type_is_T_or_C) {
                                partition_t *Q = NULL;
 
-                               DB((dbg, LEVEL_2, "WHAT = lambda n.(n.opcode) on part%d\n", Y->nr));
+                               DEBUG_ONLY(what_reason = "lambda n.(n.opcode)";)
                                Q = split_by_what(Y, lambda_opcode, &Q, env);
+                               dump_split_list(Q);
 
                                do {
                                        partition_t *Z = Q;
@@ -1200,6 +1774,11 @@ static void split_by(partition_t *X, environment_t *env) {
                                                const node_t *first = get_first_node(Z);
                                                int          arity  = get_irn_arity(first->node);
                                                partition_t  *R, *S;
+                                               what_func    what = lambda_partition;
+                                               DEBUG_ONLY(char buf[64];)
+
+                                               if (env->commutative && is_op_commutative(get_irn_op(first->node)))
+                                                       what = lambda_commutative_partition;
 
                                                /*
                                                 * BEWARE: during splitting by input 2 for instance we might
@@ -1216,8 +1795,10 @@ static void split_by(partition_t *X, environment_t *env) {
                                                                R = R->split_next;
                                                                if (Z_prime->n_leader > 1) {
                                                                        env->lambda_input = input;
-                                                                       DB((dbg, LEVEL_2, "WHAT = lambda n.(n[%d].partition) on part%d\n", input, Z_prime->nr));
-                                                                       S = split_by_what(Z_prime, lambda_partition, &S, env);
+                                                                       DEBUG_ONLY(snprintf(buf, sizeof(buf), "lambda n.(n[%d].partition)", input);)
+                                                                       DEBUG_ONLY(what_reason = buf;)
+                                                                       S = split_by_what(Z_prime, what, &S, env);
+                                                                       dump_split_list(S);
                                                                } else {
                                                                        Z_prime->split_next = S;
                                                                        S                   = Z_prime;
@@ -1317,10 +1898,8 @@ static void compute_Unknown(node_t *node) {
         * nodes are inputs to Conds. We check that first.
         * This is the way Frontends typically build Firm, but some optimizations
         * (cond_eval for instance) might replace them by Phib's...
-        *
-        * For now, we compute bottom here.
         */
-       node->type.tv = tarval_bottom;
+       node->type.tv = tarval_UNKNOWN;
 }  /* compute_Unknown */
 
 /**
@@ -1334,6 +1913,18 @@ static void compute_Jmp(node_t *node) {
        node->type = block->type;
 }  /* compute_Jmp */
 
+/**
+ * (Re-)compute the type for the Return node.
+ *
+ * @param node  the node
+ */
+static void compute_Return(node_t *node) {
+       /* The Return node is NOT dead if it is in a reachable block.
+        * This is already checked in compute(). so we can return
+        * Reachable here. */
+       node->type.tv = tarval_reachable;
+}  /* compute_Return */
+
 /**
  * (Re-)compute the type for the End node.
  *
@@ -1342,7 +1933,7 @@ static void compute_Jmp(node_t *node) {
 static void compute_End(node_t *node) {
        /* the End node is NOT dead of course */
        node->type.tv = tarval_reachable;
-}
+}  /* compute_End */
 
 /**
  * (Re-)compute the type for a SymConst node.
@@ -1491,7 +2082,8 @@ static void compute_Sub(node_t *node) {
                tv = get_mode_null(mode);
 
                /* if the node was ONCE evaluated by all constants, but now
-                  this breakes AND we cat by partition a different result, switch to bottom.
+                  this breaks AND we get from the argument partitions a different
+                  result, switch to bottom.
                   This happens because initially all nodes are in the same partition ... */
                if (node->by_all_const && node->type.tv != tv)
                        tv = tarval_bottom;
@@ -1501,6 +2093,48 @@ static void compute_Sub(node_t *node) {
        }
 }  /* compute_Sub */
 
+/**
+ * (Re-)compute the type for an Eor. Special case: both nodes are congruent.
+ *
+ * @param node  the node
+ */
+static void compute_Eor(node_t *node) {
+       ir_node        *eor = node->node;
+       node_t         *l   = get_irn_node(get_Eor_left(eor));
+       node_t         *r   = get_irn_node(get_Eor_right(eor));
+       lattice_elem_t a    = l->type;
+       lattice_elem_t b    = r->type;
+       tarval         *tv;
+
+       if (a.tv == tarval_top || b.tv == tarval_top) {
+               node->type.tv = tarval_top;
+       } else if (is_con(a) && is_con(b)) {
+               if (is_tarval(a.tv) && is_tarval(b.tv)) {
+                       node->type.tv = tarval_eor(a.tv, b.tv);
+               } else if (is_tarval(a.tv) && tarval_is_null(a.tv)) {
+                       node->type = b;
+               } else if (is_tarval(b.tv) && tarval_is_null(b.tv)) {
+                       node->type = a;
+               } else {
+                       node->type.tv = tarval_bottom;
+               }
+               node->by_all_const = 1;
+       } else if (r->part == l->part) {
+               ir_mode *mode = get_irn_mode(eor);
+               tv = get_mode_null(mode);
+
+               /* if the node was ONCE evaluated by all constants, but now
+                  this breaks AND we get from the argument partitions a different
+                  result, switch to bottom.
+                  This happens because initially all nodes are in the same partition ... */
+               if (node->by_all_const && node->type.tv != tv)
+                       tv = tarval_bottom;
+               node->type.tv = tv;
+       } else {
+               node->type.tv = tarval_bottom;
+       }
+}  /* compute_Eor */
+
 /**
  * (Re-)compute the type for Cmp.
  *
@@ -1515,16 +2149,16 @@ static void compute_Cmp(node_t *node) {
 
        if (a.tv == tarval_top || b.tv == tarval_top) {
                node->type.tv = tarval_top;
-       } else if (is_con(a) && is_con(b)) {
-               /* both nodes are constants, we can probably do something */
-               node->type.tv = tarval_b_true;
        } else if (r->part == l->part) {
                /* both nodes congruent, we can probably do something */
                node->type.tv = tarval_b_true;
+       } else if (is_con(a) && is_con(b)) {
+               /* both nodes are constants, we can probably do something */
+               node->type.tv = tarval_b_true;
        } else {
                node->type.tv = tarval_bottom;
        }
-}  /* compute_Proj_Cmp */
+}  /* compute_Cmp */
 
 /**
  * (Re-)compute the type for a Proj(Cmp).
@@ -1542,7 +2176,7 @@ static void compute_Proj_Cmp(node_t *node, ir_node *cmp) {
        tarval         *tv;
 
        if (a.tv == tarval_top || b.tv == tarval_top) {
-               node->type.tv = tarval_top;
+               node->type.tv = tarval_undefined;
        } else if (is_con(a) && is_con(b)) {
                default_compute(node);
                node->by_all_const = 1;
@@ -1552,10 +2186,11 @@ static void compute_Proj_Cmp(node_t *node, ir_node *cmp) {
                 * BEWARE: a == a is NOT always True for floating Point values, as
                 * NaN != NaN is defined, so we must check this here.
                 */
-               tv = new_tarval_from_long(pnc & pn_Cmp_Eq, mode_b);
+               tv = pnc & pn_Cmp_Eq ? tarval_b_true: tarval_b_false;
 
                /* if the node was ONCE evaluated by all constants, but now
-                  this breakes AND we cat by partition a different result, switch to bottom.
+                  this breaks AND we get from the argument partitions a different
+                  result, switch to bottom.
                   This happens because initially all nodes are in the same partition ... */
                if (node->by_all_const && node->type.tv != tv)
                        tv = tarval_bottom;
@@ -1588,6 +2223,7 @@ static void compute_Proj_Cond(node_t *node, ir_node *cond) {
                                node->type.tv = tarval_reachable;
                        } else {
                                assert(selector->type.tv == tarval_top);
+                               /* any condition based on Top is "!=" */
                                node->type.tv = tarval_unreachable;
                        }
                } else {
@@ -1601,7 +2237,8 @@ static void compute_Proj_Cond(node_t *node, ir_node *cond) {
                                node->type.tv = tarval_reachable;
                        } else {
                                assert(selector->type.tv == tarval_top);
-                               node->type.tv = tarval_unreachable;
+                               /* any condition based on Top is "!=" */
+                               node->type.tv = tarval_reachable;
                        }
                }
        } else {
@@ -1609,7 +2246,11 @@ static void compute_Proj_Cond(node_t *node, ir_node *cond) {
                if (selector->type.tv == tarval_bottom) {
                        node->type.tv = tarval_reachable;
                } else if (selector->type.tv == tarval_top) {
-                       node->type.tv = tarval_unreachable;
+                       if (pnc == get_Cond_defaultProj(cond)) {
+                               /* a switch based of Top is always "default" */
+                               node->type.tv = tarval_reachable;
+                       } else
+                               node->type.tv = tarval_unreachable;
                } else {
                        long value = get_tarval_long(selector->type.tv);
                        if (pnc == get_Cond_defaultProj(cond)) {
@@ -1653,7 +2294,7 @@ static void compute_Proj(node_t *node) {
                node->type.tv = tarval_top;
                return;
        }
-       if (get_irn_node(pred)->type.tv == tarval_top) {
+       if (get_irn_node(pred)->type.tv == tarval_top && !is_Cond(pred)) {
                /* if the predecessor is Top, its Proj follow */
                node->type.tv = tarval_top;
                return;
@@ -1715,18 +2356,18 @@ static void compute_Confirm(node_t *node) {
  * @param node  the node
  */
 static void compute_Max(node_t *node) {
-       ir_node        *op   = node->node;
-       node_t         *l    = get_irn_node(get_binop_left(op));
-       node_t         *r    = get_irn_node(get_binop_right(op));
-       lattice_elem_t a     = l->type;
-       lattice_elem_t b     = r->type;
+       ir_node        *op = node->node;
+       node_t         *l  = get_irn_node(get_binop_left(op));
+       node_t         *r  = get_irn_node(get_binop_right(op));
+       lattice_elem_t a   = l->type;
+       lattice_elem_t b   = r->type;
 
        if (a.tv == tarval_top || b.tv == tarval_top) {
                node->type.tv = tarval_top;
        } else if (is_con(a) && is_con(b)) {
                /* both nodes are constants, we can probably do something */
                if (a.tv == b.tv) {
-                       /* this case handles symconsts as well */
+                       /* this case handles SymConsts as well */
                        node->type = a;
                } else {
                        ir_mode *mode   = get_irn_mode(op);
@@ -1759,18 +2400,18 @@ static void compute_Max(node_t *node) {
  * @param node  the node
  */
 static void compute_Min(node_t *node) {
-       ir_node        *op   = node->node;
-       node_t         *l    = get_irn_node(get_binop_left(op));
-       node_t         *r    = get_irn_node(get_binop_right(op));
-       lattice_elem_t a     = l->type;
-       lattice_elem_t b     = r->type;
+       ir_node        *op = node->node;
+       node_t         *l  = get_irn_node(get_binop_left(op));
+       node_t         *r  = get_irn_node(get_binop_right(op));
+       lattice_elem_t a   = l->type;
+       lattice_elem_t b   = r->type;
 
        if (a.tv == tarval_top || b.tv == tarval_top) {
                node->type.tv = tarval_top;
        } else if (is_con(a) && is_con(b)) {
                /* both nodes are constants, we can probably do something */
                if (a.tv == b.tv) {
-                       /* this case handles symconsts as well */
+                       /* this case handles SymConsts as well */
                        node->type = a;
                } else {
                        ir_mode *mode   = get_irn_mode(op);
@@ -1803,14 +2444,18 @@ static void compute_Min(node_t *node) {
  * @param node  the node
  */
 static void compute(node_t *node) {
+       ir_node *irn = node->node;
        compute_func func;
 
-       if (is_no_Block(node->node)) {
-               node_t *block = get_irn_node(get_nodes_block(node->node));
+       if (is_no_Block(irn)) {
+               /* for pinned nodes, check its control input */
+               if (get_irn_pinned(skip_Proj(irn)) == op_pin_state_pinned) {
+                       node_t *block = get_irn_node(get_nodes_block(irn));
 
-               if (block->type.tv == tarval_unreachable) {
-                       node->type.tv = tarval_top;
-                       return;
+                       if (block->type.tv == tarval_unreachable) {
+                               node->type.tv = tarval_top;
+                               return;
+                       }
                }
        }
 
@@ -1880,8 +2525,22 @@ static node_t *identity_comm_zero_binop(node_t *node) {
        return node;
 }  /* identity_comm_zero_binop */
 
-#define identity_Add  identity_comm_zero_binop
-#define identity_Or   identity_comm_zero_binop
+/**
+ * Calculates the Identity for Shift nodes.
+ */
+static node_t *identity_shift(node_t *node) {
+       ir_node *op   = node->node;
+       node_t  *b    = get_irn_node(get_binop_right(op));
+       ir_mode *mode = get_irn_mode(b->node);
+       tarval  *zero;
+
+       /* node: no input should be tarval_top, else the binop would be also
+        * Top and not being split. */
+       zero = get_mode_null(mode);
+       if (b->type.tv == zero)
+               return get_irn_node(get_binop_left(op));
+       return node;
+}  /* identity_shift */
 
 /**
  * Calculates the Identity for Mul nodes.
@@ -1924,7 +2583,7 @@ static node_t *identity_Sub(node_t *node) {
        if (b->type.tv == get_mode_null(mode))
                return get_irn_node(get_Sub_left(sub));
        return node;
-}  /* identity_Mul */
+}  /* identity_Sub */
 
 /**
  * Calculates the Identity for And nodes.
@@ -1959,18 +2618,23 @@ static node_t *identity_Confirm(node_t *node) {
  */
 static node_t *identity_Mux(node_t *node) {
        ir_node *mux = node->node;
-       node_t  *sel = get_irn_node(get_Mux_sel(mux));
        node_t  *t   = get_irn_node(get_Mux_true(mux));
        node_t  *f   = get_irn_node(get_Mux_false(mux));
+       /*node_t  *sel; */
 
        if (t->part == f->part)
                return t;
 
+       /* for now, the 1-input identity is not supported */
+#if 0
+       sel = get_irn_node(get_Mux_sel(mux));
+
        /* Mux sel input is mode_b, so it is always a tarval */
        if (sel->type.tv == tarval_b_true)
                return t;
        if (sel->type.tv == tarval_b_false)
                return f;
+#endif
        return node;
 }  /* identity_Mux */
 
@@ -2031,14 +2695,21 @@ static node_t *identity(node_t *node) {
        switch (get_irn_opcode(irn)) {
        case iro_Phi:
                return identity_Phi(node);
+       case iro_Mul:
+               return identity_Mul(node);
        case iro_Add:
-               return identity_Add(node);
        case iro_Or:
-               return identity_Or(node);
+       case iro_Eor:
+               return identity_comm_zero_binop(node);
+       case iro_Shr:
+       case iro_Shl:
+       case iro_Shrs:
+       case iro_Rotl:
+               return identity_shift(node);
+       case iro_And:
+               return identity_And(node);
        case iro_Sub:
                return identity_Sub(node);
-       case iro_And:
-               return identity_Add(node);
        case iro_Confirm:
                return identity_Confirm(node);
        case iro_Mux:
@@ -2057,7 +2728,7 @@ static node_t *identity(node_t *node) {
  * out edges.
  */
 static void segregate_def_use_chain_1(const ir_node *follower, node_t *leader) {
-       ir_node *l = leader->node;
+       ir_node *l   = leader->node;
        int     j, i, n = get_irn_n_outs(l);
 
        DB((dbg, LEVEL_2, "%+F is a follower of %+F\n", follower, leader->node));
@@ -2071,95 +2742,27 @@ static void segregate_def_use_chain_1(const ir_node *follower, node_t *leader) {
                                l->out[j + 1] = l->out[j];
                        ++leader->n_followers;
                        l->out[leader->n_followers] = t;
-
-                       /* note: a node might be a n-fold follower, for instance
-                        * if x = max(a,a), so no break here. */
+                       break;
                }
        }
 }  /* segregate_def_use_chain_1 */
 
 /**
- * Node follower is a (new) follower of leader, segregate Leader
- * out edges. If follower is a n-congruent Input identity, all follower
- * inputs congruent to follower are also leader.
+ * Node follower is a (new) follower segregate its Leader
+ * out edges.
+ *
+ * @param follower  the follower IR node
  */
-static void segregate_def_use_chain(const ir_node *follower, node_t *leader) {
-       ir_op *op = get_irn_op(follower);
-
-       if (op == op_Phi) {
-               /* n-Congruent Input Identity for Phi's */
-               int i;
-               ir_node *block = get_nodes_block(follower);
-
-               DB((dbg, LEVEL_2, "n-Congruent follower %+F\n", follower));
-               for (i = get_irn_arity(follower) - 1; i >= 0; --i) {
-                       node_t *pred_X = get_irn_node(get_Block_cfgpred(block, i));
-
-                       /* beware: we are NOT followers of dead inputs */
-                       if (pred_X->type.tv == tarval_reachable) {
-                               node_t *pred = get_irn_node(get_irn_n(follower, i));
-
-                               if (pred->part == leader->part)
-                                       segregate_def_use_chain_1(follower, pred);
-                       }
-               }
-       } else if (op == op_Mux || op == op_Max || op == op_Min) {
-               /* n-Congruent Input Identity */
-               int i;
+static void segregate_def_use_chain(const ir_node *follower) {
+       int i;
 
-               DB((dbg, LEVEL_2, "n-Congruent follower %+F\n", follower));
-               for (i = get_irn_arity(follower) - 1; i >= 0; --i) {
-                       node_t *pred = get_irn_node(get_irn_n(follower, i));
+       for (i = get_irn_arity(follower) - 1; i >= 0; --i) {
+               node_t *pred = get_irn_node(get_irn_n(follower, i));
 
-                       if (pred->part == leader->part)
-                               segregate_def_use_chain_1(follower, pred);
-               }
-       } else {
-               /* 1-Congruent Input Identity */
-               segregate_def_use_chain_1(follower, leader);
+               segregate_def_use_chain_1(follower, pred);
        }
 }  /* segregate_def_use_chain */
 
-/**
- * Make all inputs to x from inside X no longer be F.def_use edges.
- */
-static void move_edges_to_leader(node_t *x) {
-       partition_t *X   = x->part;
-       ir_node     *irn = x->node;
-       int         i, j, k;
-
-       for (i = get_irn_arity(irn) - 1; i >= 0; --i) {
-               node_t  *pred = get_irn_node(get_irn_n(irn, i));
-               ir_node *p;
-               int     n;
-
-               p = pred->node;
-               n = get_irn_n_outs(p);
-               for (j = 1; j <= pred->n_followers; ++j) {
-                       if (p->out[j].pos == i && p->out[j].use == irn) {
-                               /* found a follower edge to x, move it to the Leader */
-                               ir_def_use_edge edge = p->out[j];
-
-                               /* remove this edge from the Follower set */
-                               p->out[j] = p->out[pred->n_followers];
-                               --pred->n_followers;
-
-                               /* sort it into the leader set */
-                               for (k = pred->n_followers + 2; k <= n; ++k) {
-                                       if (p->out[k].pos >= edge.pos)
-                                               break;
-                                       p->out[k - 1] = p->out[k];
-                               }
-                               /* place the new edge here */
-                               p->out[k - 1] = edge;
-
-                               /* edge found and moved */
-                               break;
-                       }
-               }
-       }
-}
-
 /**
  * Propagate constant evaluation.
  *
@@ -2189,32 +2792,28 @@ static void propagate(environment_t *env) {
                while (! list_empty(&X->cprop)) {
                        /* remove the first Node x from X.cprop */
                        x = list_entry(X->cprop.next, node_t, cprop_list);
+                       //assert(x->part == X);
                        list_del(&x->cprop_list);
                        x->on_cprop = 0;
 
                        if (x->is_follower && identity(x) == x) {
-                               /* x will make the follower -> leader transition */
-                               DB((dbg, LEVEL_2, "%+F make the follower -> leader transition\n", x->node));
+                               /* check the opcode first */
                                if (oldopcode == NULL) {
                                        oldopcode = lambda_opcode(get_first_node(X), env);
                                }
                                if (oldopcode != lambda_opcode(x, env)) {
-                                       /* different opcode -> x falls out of this partition */
-                                       x->next      = fallen;
-                                       x->on_fallen = 1;
-                                       fallen       = x;
-                                       ++n_fallen;
-                                       DB((dbg, LEVEL_2, "Add node %+F to fallen\n", x->node));
+                                       if (x->on_fallen == 0) {
+                                               /* different opcode -> x falls out of this partition */
+                                               x->next      = fallen;
+                                               x->on_fallen = 1;
+                                               fallen       = x;
+                                               ++n_fallen;
+                                               DB((dbg, LEVEL_2, "Add node %+F to fallen\n", x->node));
+                                       }
                                }
 
-                               /* move x from X.Follower to X.Leader */
-                               list_del(&x->node_list);
-                               list_add_tail(&x->node_list, &X->Leader);
-                               x->is_follower = 0;
-                               X->n_leader++;
-
-                               /* Make all inputs to x from inside X no longer be F.def_use edges */
-                               move_edges_to_leader(x);
+                               /* x will make the follower -> leader transition */
+                               follower_to_leader(x);
                        }
 
                        /* compute a new type for x */
@@ -2239,14 +2838,19 @@ static void propagate(environment_t *env) {
                                        node_t  *y    = get_irn_node(succ);
 
                                        /* Add y to y.partition.cprop. */
-                                       add_node_to_cprop(y, env);
+                                       add_to_cprop(y, env);
                                }
                        }
                }
 
                if (n_fallen > 0 && n_fallen != X->n_leader) {
                        DB((dbg, LEVEL_2, "Splitting part%d by fallen\n", X->nr));
-                       Y = split(X, fallen, env);
+                       Y = split(&X, fallen, env);
+                       /*
+                        * We have split out fallen node. The type of the result
+                        * partition is NOT set yet.
+                        */
+                       Y->type_is_T_or_C = 0;
                } else {
                        Y = X;
                }
@@ -2254,29 +2858,27 @@ static void propagate(environment_t *env) {
                for (x = fallen; x != NULL; x = x->next)
                        x->on_fallen = 0;
 
-#ifndef NO_FOLLOWER
                if (old_type_was_T_or_C) {
                        node_t *y, *tmp;
 
                        /* check if some nodes will make the leader -> follower transition */
                        list_for_each_entry_safe(node_t, y, tmp, &Y->Leader, node_list) {
-                               if (! is_con(y->type)) {
+                               if (y->type.tv != tarval_top && ! is_con(y->type)) {
                                        node_t *eq_node = identity(y);
 
-                                       if (eq_node != y) {
+                                       if (eq_node != y && eq_node->part == y->part) {
                                                DB((dbg, LEVEL_2, "Node %+F is a follower of %+F\n", y->node, eq_node->node));
                                                /* move to Follower */
                                                y->is_follower = 1;
                                                list_del(&y->node_list);
+                                               list_add_tail(&y->node_list, &Y->Follower);
                                                --Y->n_leader;
 
-                                               list_add_tail(&y->node_list, &Y->Follower);
-                                               segregate_def_use_chain(y->node, eq_node);
+                                               segregate_def_use_chain(y->node);
                                        }
                                }
                        }
                }
-#endif
                split_by(Y, env);
        }
 }  /* propagate */
@@ -2290,7 +2892,11 @@ static ir_node *get_leader(node_t *node) {
        partition_t *part = node->part;
 
        if (part->n_leader > 1 || node->is_follower) {
-               DB((dbg, LEVEL_2, "Found congruence class for %+F\n", node->node));
+               if (node->is_follower) {
+                       DB((dbg, LEVEL_2, "Replacing follower %+F\n", node->node));
+               }
+               else
+                       DB((dbg, LEVEL_2, "Found congruence class for %+F\n", node->node));
 
                return get_first_node(part)->node;
        }
@@ -2312,7 +2918,7 @@ static int can_exchange(ir_node *pred) {
                int i, k;
 
                /* if the predecessor block has more than one
-               reachable outputs we cannot remove the block */
+                  reachable outputs we cannot remove the block */
                k = 0;
                for (i = get_irn_n_outs(pred) - 1; i >= 0; --i) {
                        ir_node *proj = get_irn_out(pred, i);
@@ -2331,7 +2937,7 @@ static int can_exchange(ir_node *pred) {
                return 1;
        }
        return 0;
-}
+}  /* can_exchange */
 
 /**
  * Block Post-Walker, apply the analysis results on control flow by
@@ -2344,26 +2950,55 @@ static void apply_cf(ir_node *block, void *ctx) {
        ir_node       **ins, **in_X;
        ir_node       *phi, *next;
 
-       if (block == get_irg_end_block(current_ir_graph) ||
-           block == get_irg_start_block(current_ir_graph)) {
+       n = get_Block_n_cfgpreds(block);
+
+       if (node->type.tv == tarval_unreachable) {
+               env->modified = 1;
+
+               for (i = n - 1; i >= 0; --i) {
+                       ir_node *pred = get_Block_cfgpred(block, i);
+
+                       if (! is_Bad(pred)) {
+                               node_t *pred_bl = get_irn_node(get_nodes_block(skip_Proj(pred)));
+
+                               if (pred_bl->flagged == 0) {
+                                       pred_bl->flagged = 3;
+
+                                       if (pred_bl->type.tv == tarval_reachable) {
+                                               /*
+                                                * We will remove an edge from block to its pred.
+                                                * This might leave the pred block as an endless loop
+                                                */
+                                               if (! is_backedge(block, i))
+                                                       keep_alive(pred_bl->node);
+                                       }
+                               }
+                       }
+               }
+
                /* the EndBlock is always reachable even if the analysis
                   finds out the opposite :-) */
+               if (block != get_irg_end_block(current_ir_graph)) {
+                       /* mark dead blocks */
+                       set_Block_dead(block);
+                       DB((dbg, LEVEL_1, "Removing dead %+F\n", block));
+               } else {
+                       /* the endblock is unreachable */
+                       set_irn_in(block, 0, NULL);
+               }
                return;
        }
-       if (node->type.tv == tarval_unreachable) {
-               /* mark dead blocks */
-               set_Block_dead(block);
-               return;
-       }
-
-       n = get_Block_n_cfgpreds(block);
 
        if (n == 1) {
                /* only one predecessor combine */
                ir_node *pred = skip_Proj(get_Block_cfgpred(block, 0));
 
                if (can_exchange(pred)) {
-                       exchange(block, get_nodes_block(pred));
+                       ir_node *new_block = get_nodes_block(pred);
+                       DB((dbg, LEVEL_1, "Fuse %+F with %+F\n", block, new_block));
+                       DBG_OPT_COMBO(block, new_block, FS_OPT_COMBO_CF);
+                       exchange(block, new_block);
+                       node->node = new_block;
                        env->modified = 1;
                }
                return;
@@ -2377,6 +3012,24 @@ static void apply_cf(ir_node *block, void *ctx) {
 
                if (node->type.tv == tarval_reachable) {
                        in_X[k++] = pred;
+               } else {
+                       DB((dbg, LEVEL_1, "Removing dead input %d from %+F (%+F)\n", i, block, pred));
+                       if (! is_Bad(pred)) {
+                               node_t *pred_bl = get_irn_node(get_nodes_block(skip_Proj(pred)));
+
+                               if (pred_bl->flagged == 0) {
+                                       pred_bl->flagged = 3;
+
+                                       if (pred_bl->type.tv == tarval_reachable) {
+                                               /*
+                                                * We will remove an edge from block to its pred.
+                                                * This might leave the pred block as an endless loop
+                                                */
+                                               if (! is_backedge(block, i))
+                                                       keep_alive(pred_bl->node);
+                                       }
+                               }
+                       }
                }
        }
        if (k >= n)
@@ -2395,6 +3048,7 @@ static void apply_cf(ir_node *block, void *ctx) {
                        set_irn_node(c, node);
                        node->node = c;
                        DB((dbg, LEVEL_1, "%+F is replaced by %+F\n", phi, c));
+                       DBG_OPT_COMBO(phi, c, FS_OPT_COMBO_CONST);
                        exchange(phi, c);
                        env->modified = 1;
                } else {
@@ -2406,13 +3060,16 @@ static void apply_cf(ir_node *block, void *ctx) {
                                        ins[j++] = get_Phi_pred(phi, i);
                                }
                        }
-                       if (j <= 1) {
+                       if (j == 1) {
                                /* this Phi is replaced by a single predecessor */
                                ir_node *s = ins[0];
+                               node_t *phi_node = get_irn_node(phi);
 
                                node->node = s;
                                DB((dbg, LEVEL_1, "%+F is replaced by %+F because of cf change\n", phi, s));
+                               DBG_OPT_COMBO(phi, s, FS_OPT_COMBO_FOLLOWER);
                                exchange(phi, s);
+                               phi_node->node = s;
                                env->modified = 1;
                        } else {
                                set_irn_in(phi, j, ins);
@@ -2421,18 +3078,42 @@ static void apply_cf(ir_node *block, void *ctx) {
                }
        }
 
-       if (k <= 1) {
+       if (k == 1) {
                /* this Block has only one live predecessor */
                ir_node *pred = skip_Proj(in_X[0]);
 
                if (can_exchange(pred)) {
-                       exchange(block, get_nodes_block(pred));
+                       ir_node *new_block = get_nodes_block(pred);
+                       DBG_OPT_COMBO(block, new_block, FS_OPT_COMBO_CF);
+                       exchange(block, new_block);
+                       node->node = new_block;
                        env->modified = 1;
                }
        } else {
                set_irn_in(block, k, in_X);
                env->modified = 1;
        }
+}  /* apply_cf */
+
+/**
+ * Exchange a node by its leader.
+ * Beware: in rare cases the mode might be wrong here, for instance
+ * AddP(x, NULL) is a follower of x, but with different mode.
+ * Fix it here.
+ */
+static void exchange_leader(ir_node *irn, ir_node *leader) {
+       ir_mode *mode = get_irn_mode(irn);
+       if (mode != get_irn_mode(leader)) {
+               /* The conv is a no-op, so we are fre to place in
+                * either in the block of the leader OR in irn's block.
+                * Probably placing it into leaders block might reduce
+                * the number of Conv due to CSE. */
+               ir_node  *block = get_nodes_block(leader);
+               dbg_info *dbg   = get_irn_dbg_info(irn);
+
+               leader = new_rd_Conv(dbg, current_ir_graph, block, leader, mode);
+       }
+       exchange(irn, leader);
 }
 
 /**
@@ -2459,14 +3140,17 @@ static void apply_result(ir_node *irn, void *ctx) {
                        env->modified = 1;
                }
                else if (node->type.tv == tarval_unreachable) {
-                       ir_node *bad = get_irg_bad(current_ir_graph);
-
-                       /* see comment above */
-                       set_irn_node(bad, node);
-                       node->node = bad;
-                       DB((dbg, LEVEL_1, "%+F is unreachable\n", irn));
-                       exchange(irn, bad);
-                       env->modified = 1;
+                       /* don't kick away Unknown */
+                       if (! is_Unknown(irn)) {
+                               ir_node *bad = get_irg_bad(current_ir_graph);
+
+                               /* see comment above */
+                               set_irn_node(bad, node);
+                               node->node = bad;
+                               DB((dbg, LEVEL_1, "%+F is unreachable\n", irn));
+                               exchange(irn, bad);
+                               env->modified = 1;
+                       }
                }
                else if (get_irn_mode(irn) == mode_X) {
                        if (is_Proj(irn)) {
@@ -2477,11 +3161,12 @@ static void apply_result(ir_node *irn, void *ctx) {
                                        node_t *sel = get_irn_node(get_Cond_selector(cond));
 
                                        if (is_tarval(sel->type.tv) && tarval_is_constant(sel->type.tv)) {
-                                               /* Cond selector is a constant, make a Jmp */
-                                               ir_node *jmp = new_r_Jmp(current_ir_graph, block->node);
+                                               /* Cond selector is a constant and the Proj is reachable, make a Jmp */
+                                               ir_node *jmp  = new_r_Jmp(current_ir_graph, block->node);
                                                set_irn_node(jmp, node);
                                                node->node = jmp;
                                                DB((dbg, LEVEL_1, "%+F is replaced by %+F\n", irn, jmp));
+                                               DBG_OPT_COMBO(irn, jmp, FS_OPT_COMBO_CF);
                                                exchange(irn, jmp);
                                                env->modified = 1;
                                        }
@@ -2502,33 +3187,88 @@ static void apply_result(ir_node *irn, void *ctx) {
                                        set_irn_node(c, node);
                                        node->node = c;
                                        DB((dbg, LEVEL_1, "%+F is replaced by %+F\n", irn, c));
-                                       exchange(irn, c);
+                                       DBG_OPT_COMBO(irn, c, FS_OPT_COMBO_CONST);
+                                       exchange_leader(irn, c);
                                        env->modified = 1;
                                }
                        } else if (is_entity(node->type.sym.entity_p)) {
                                if (! is_SymConst(irn)) {
-                                       /* can be replaced by a Symconst */
+                                       /* can be replaced by a SymConst */
                                        ir_node *symc = new_r_SymConst(current_ir_graph, block->node, get_irn_mode(irn), node->type.sym, symconst_addr_ent);
                                        set_irn_node(symc, node);
                                        node->node = symc;
 
                                        DB((dbg, LEVEL_1, "%+F is replaced by %+F\n", irn, symc));
-                                       exchange(irn, symc);
+                                       DBG_OPT_COMBO(irn, symc, FS_OPT_COMBO_CONST);
+                                       exchange_leader(irn, symc);
                                        env->modified = 1;
                                }
+                       } else if (is_Confirm(irn)) {
+                               /* Confirms are always follower, but do not kill them here */
                        } else {
                                ir_node *leader = get_leader(node);
 
                                if (leader != irn) {
-                                       DB((dbg, LEVEL_1, "%+F from part%d is replaced by %+F\n", irn, node->part->nr, leader));
-                                       exchange(irn, leader);
-                                       env->modified = 1;
+                                       int non_strict_phi = 0;
+
+                                       /*
+                                        * Beware: Do not remove Phi(Unknown, ..., x, ..., Unknown)
+                                        * as this might create non-strict programs.
+                                        */
+                                       if (node->is_follower && is_Phi(irn) && !is_Unknown(leader)) {
+                                               int i;
+
+                                               for (i = get_Phi_n_preds(irn) - 1; i >= 0; --i) {
+                                                       ir_node *pred = get_Phi_pred(irn, i);
+
+                                                       if (is_Unknown(pred)) {
+                                                               non_strict_phi = 1;
+                                                               break;
+                                                       }
+                                               }
+                                       }
+                                       if (! non_strict_phi) {
+                                               DB((dbg, LEVEL_1, "%+F from part%d is replaced by %+F\n", irn, node->part->nr, leader));
+                                               if (node->is_follower)
+                                                       DBG_OPT_COMBO(irn, leader, FS_OPT_COMBO_FOLLOWER);
+                                               else
+                                                       DBG_OPT_COMBO(irn, leader, FS_OPT_COMBO_CONGRUENT);
+                                               exchange_leader(irn, leader);
+                                               env->modified = 1;
+                                       }
                                }
                        }
                }
        }
 }  /* apply_result */
 
+/**
+ * Fix the keep-alives by deleting unreachable ones.
+ */
+static void apply_end(ir_node *end, environment_t *env) {
+       int i, j,  n = get_End_n_keepalives(end);
+       ir_node **in;
+
+       if (n > 0)
+               NEW_ARR_A(ir_node *, in, n);
+
+       /* fix the keep alive */
+       for (i = j = 0; i < n; i++) {
+               ir_node *ka   = get_End_keepalive(end, i);
+               node_t  *node = get_irn_node(ka);
+
+               if (! is_Block(ka))
+                       node = get_irn_node(get_nodes_block(ka));
+
+               if (node->type.tv != tarval_unreachable && !is_Bad(ka))
+                       in[j++] = ka;
+       }
+       if (j != n) {
+               set_End_keepalives(end, j, in);
+               env->modified = 1;
+       }
+}  /* apply_end */
+
 #define SET(code) op_##code->ops.generic = (op_func)compute_##code
 
 /**
@@ -2551,10 +3291,12 @@ static void set_compute_functions(void) {
        SET(Phi);
        SET(Add);
        SET(Sub);
+       SET(Eor);
        SET(SymConst);
        SET(Cmp);
        SET(Proj);
        SET(Confirm);
+       SET(Return);
        SET(End);
 
        if (op_Max != NULL)
@@ -2564,14 +3306,6 @@ static void set_compute_functions(void) {
 
 }  /* set_compute_functions */
 
-static int dump_partition_hook(FILE *F, ir_node *n, ir_node *local) {
-       ir_node *irn = local != NULL ? local : n;
-       node_t *node = get_irn_node(irn);
-
-       ir_fprintf(F, "info2 : \"partition %u type %+F\"\n", node->part->nr, node->type);
-       return 1;
-}
-
 void combo(ir_graph *irg) {
        environment_t env;
        ir_node       *initial_bl;
@@ -2582,7 +3316,6 @@ void combo(ir_graph *irg) {
 
        /* register a debug mask */
        FIRM_DBG_REGISTER(dbg, "firm.opt.combo");
-       firm_dbg_set_mask(dbg, SET_LEVEL_3);
 
        DB((dbg, LEVEL_1, "Doing COMBO for %+F\n", irg));
 
@@ -2598,9 +3331,11 @@ void combo(ir_graph *irg) {
        env.type2id_map    = pmap_create();
        env.end_idx        = get_opt_global_cse() ? 0 : -1;
        env.lambda_input   = 0;
+       env.commutative    = 1;
        env.modified       = 0;
 
        assure_irg_outs(irg);
+       assure_cf_loop(irg);
 
        /* we have our own value_of function */
        set_value_of_func(get_node_tarval);
@@ -2608,11 +3343,22 @@ void combo(ir_graph *irg) {
        set_compute_functions();
        DEBUG_ONLY(part_nr = 0);
 
+       ir_reserve_resources(irg, IR_RESOURCE_IRN_LINK);
+
        /* create the initial partition and place it on the work list */
        env.initial = new_partition(&env);
        add_to_worklist(env.initial, &env);
        irg_walk_graph(irg, init_block_phis, create_initial_partitions, &env);
 
+       /* set the hook: from now, every node has a partition and a type */
+       DEBUG_ONLY(set_dump_node_vcgattr_hook(dump_partition_hook));
+
+#ifdef WITH_UNKNOWN
+       tarval_UNKNOWN = tarval_top;
+#else
+       tarval_UNKNOWN = tarval_bad;
+#endif
+
        /* all nodes on the initial partition have type Top */
        env.initial->type_is_T_or_C = 1;
 
@@ -2620,7 +3366,7 @@ void combo(ir_graph *irg) {
           Place the START Node on its local worklist. */
        initial_bl = get_irg_start_block(irg);
        start      = get_irn_node(initial_bl);
-       add_node_to_cprop(start, &env);
+       add_to_cprop(start, &env);
 
        do {
                propagate(&env);
@@ -2629,18 +3375,16 @@ void combo(ir_graph *irg) {
        } while (env.cprop != NULL || env.worklist != NULL);
 
        dump_all_partitions(&env);
+       check_all_partitions(&env);
 
 #if 0
-       set_dump_node_vcgattr_hook(dump_partition_hook);
        dump_ir_block_graph(irg, "-partition");
-       set_dump_node_vcgattr_hook(NULL);
-#else
-       (void)dump_partition_hook;
 #endif
 
        /* apply the result */
        irg_block_walk_graph(irg, NULL, apply_cf, &env);
        irg_walk_graph(irg, NULL, apply_result, &env);
+       apply_end(get_irg_end(irg), &env);
 
        if (env.modified) {
                /* control flow might changed */
@@ -2650,6 +3394,11 @@ void combo(ir_graph *irg) {
                set_irg_loopinfo_inconsistent(irg);
        }
 
+       ir_free_resources(irg, IR_RESOURCE_IRN_LINK);
+
+       /* remove the partition hook */
+       DEBUG_ONLY(set_dump_node_vcgattr_hook(NULL));
+
        pmap_destroy(env.type2id_map);
        del_set(env.opcode2id_map);
        obstack_free(&env.obst, NULL);