Refactoring

[libfirm] / ir / opt / loop.c

/*
 * Copyright (C) 1995-2008 University of Karlsruhe.  All right reserved.
 *
 * This file is part of libFirm.
 *
 * This file may be distributed and/or modified under the terms of the
 * GNU General Public License version 2 as published by the Free Software
 * Foundation and appearing in the file LICENSE.GPL included in the
 * packaging of this file.
 *
 * Licensees holding valid libFirm Professional Edition licenses may use
 * this file in accordance with the libFirm Commercial License.
 * Agreement provided with the Software.
 *
 * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
 * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE.
 */

/**
 * @file
 * @author   Christian Helmer
 * @brief    loop inversion and loop unrolling, loop peeling
 *
 * @version  $Id$
 */
#include "config.h"

#include "irnode.h"
#include "debug.h"

#include "ircons.h"
#include "irgopt.h"
#include "irgmod.h"
#include "irgwalk.h"
#include "irouts.h"
#include "iredges.h"
#include "irtools.h"
#include "array_t.h"    /* automatic array */
#include "beutil.h"             /* get_block */
#include "irloop_t.h"   /* set_irn_loop*/
#include "irpass.h"

#if 0
        #include "irdump_t.h"
#endif


DEBUG_ONLY(static firm_dbg_module_t *dbg);

/**
 * Convenience macro for iterating over every phi node of the given block.
 * Requires phi list per block.
 */
#define for_each_phi(block, phi) \
        for ( (phi) = get_Block_phis( (block) ); (phi) ; (phi) = get_Phi_next( (phi) ) )

/* current loop */
static ir_loop *cur_loop;

/* abortable walker function */
typedef unsigned irg_walk_func_abortable(ir_node *, void *);

/* condition for walking a node during a copy_walk */
typedef unsigned walker_condition(ir_node *);

/* node and position of a predecessor */
typedef struct out_edges {
        ir_node *node;
        int pred_irn_n;
} out_edge;

/* access complex values through the nodes links */
typedef struct node_info {
        unsigned invariant:1;
        ir_node *copy;
        ir_node *link;                                  /* temporary links for ssa creation */
        ir_node **ins;                                  /* ins for phi nodes, during rewiring of blocks */
        unsigned done;
        struct node_info *freelistnext; /* linked list to free all node_infos */
} node_info;

static node_info *link_node_state_list;         /* head of the linked list to free all node_infos */

static out_edge *cur_loop_outs;                         /* A walker may start visiting the current loop with these nodes. */
static out_edge *cur_head_outs;                         /* A walker may start visiting the cur head with these nodes. */

static ir_node *loop_cf_head = NULL;                            /* Loop head node */
static unsigned loop_cf_head_valid = 1;                         /* A loop may have one head, otherwise we do not touch it. */

ir_node **loops;

/* Inverted head */
static ir_node *loop_inv_head = NULL;
/* Peeled head */
static ir_node *loop_peeled_head = NULL;

/* Loop analysis informations */
typedef struct loop_info_t {
        unsigned blocks;                        /* number of blocks in the loop */
        unsigned calls;                         /* number of calls */
        unsigned loads;                         /* number of load nodes */
        unsigned outs;                          /* outs without keepalives */
#if 0
        unsigned invariant_loads;
        unsigned stores;                        /* number of store nodes */
        unsigned opnodes_n;                     /* nodes that probably result in an instruction */
        unsigned do_invariant_opt;
#endif
} loop_info_t;

/* Information about the current loop */
static loop_info_t loop_info;

/* A walker may start visiting a condition chain with these nodes. */
static out_edge *cond_chain_entries;

/* Number of unrolling */
int unroll_times;

static unsigned head_inversion_node_count;
static unsigned inversion_head_node_limit;
static unsigned head_inversion_block_count;

static unsigned enable_peeling;
static unsigned enable_inversion;
static unsigned enable_unrolling;

/**
 *
 * ============= AUXILIARY FUNCTIONS =====================================
 */


/**
 * Creates object on the heap, and adds it to a linked list to free it later.
 */
static node_info *new_node_info(void)
{
        node_info *l = XMALLOCZ(node_info);
        l->freelistnext = link_node_state_list;
        link_node_state_list = l;
        l->copy = NULL;
        l->invariant = 0;
        return l;
}

static node_info *get_node_info(ir_node *n)
{
        return ((node_info *)get_irn_link(n));
}

/* Allocates a node_info struct for the given node. For use with a walker. */
static void alloc_node_info(ir_node *node, void *env)
{
        node_info *state;
        (void) env;
        state = new_node_info();
        set_irn_link(node, (void *)state);
}

static void free_node_info(void)
{
        int a = 0;
        node_info *n;
        n = link_node_state_list;
        while (n) {
                node_info *next = n->freelistnext;
                ++a;
                xfree(n);
                n = next;
        }
        link_node_state_list = NULL;
}

/**
 * Use the linked list to reset the reused values of all node_infos
 * Reset in particular the copy attribute as copy_walk uses it to determine a present copy
 */
static void reset_node_infos(void)
{
        node_info *next;
        next = link_node_state_list;
        while (next->freelistnext) {
                node_info *cur = next;
                next = cur->freelistnext;
                cur->copy = NULL;
                cur->ins = NULL;
                cur->link = NULL;
        }
}

/* Returns the nodes node_info link. */
static ir_node *get_link(ir_node *n)
{
        return ((node_info *)get_irn_link(n))->link;
}

/* Sets the nodes node_info link. */
static void set_link(ir_node *n, ir_node *link)
{
        ((node_info *)get_irn_link(n))->link = link;
}

/* Returns a nodes copy. */
static ir_node *get_copy(ir_node *n)
{
        return ((node_info *)get_irn_link(n))->copy;
}

/* Sets a nodes copy. */
static void set_copy(ir_node *n, ir_node *copy)
{
        ((node_info *)get_irn_link(n) )->copy = copy;
}

/**
 * Convenience macro for iterating over every copy in a linked list
 * of copies.
 */
#define for_each_copy(node) \
        for ( ; (node) ; (node) = get_copy(node))

/**
 * Convenience macro for iterating over every copy in 2 linked lists
 * of copies in parallel.
 */
#define for_each_copy2(high1, low1, high2, low2) \
        for ( ; (low1) && (low2); (high1) = (low1), (low1) = get_copy(low1), \
                                                        (high2) = (low2), (low2) = get_copy(low2))

/*
 * Returns 0 if the node or block is not in cur_loop.
 */
static unsigned is_in_loop(ir_node *node)
{
        return (get_irn_loop(get_block(node)) == cur_loop);
}

/* Returns if the given be is an alien edge. This is the case when the pred is not in the loop. */
static unsigned is_alien_edge(ir_node *n, int i)
{
        return(!is_in_loop(get_irn_n(n, i)));
}

/* used for block walker */
static void reset_block_mark(ir_node *node, void * env)
{
        (void) env;

        if (is_Block(node))
                set_Block_mark(node, 0);
}

static unsigned is_nodesblock_marked(ir_node* node)
{
        return (get_Block_mark(get_block(node)));
}

/* Returns the number of blocks in a loop. */
int get_loop_n_blocks(ir_loop *loop)
{
        int elements, e;
        int blocks = 0;
        elements = get_loop_n_elements(loop);

        for (e=0; e<elements; e++) {
                loop_element elem = get_loop_element(loop, e);
                if (is_ir_node(elem.kind) && is_Block(elem.node))
                        ++blocks;
        }
        return blocks;
}

/**
 * Add newpred at position pos to node and also add the corresponding value to the phis.
 * Requires block phi list.
 */
static int duplicate_preds(ir_node* block, unsigned pos, ir_node* newpred)
{
        ir_node **ins;
        /*int *is_be;*/
        ir_node *phi;
        int block_arity;
        int i;

        assert(is_Block(block) && "duplicate_preds may be called for blocks only");

        DB((dbg, LEVEL_1, "duplicate_preds(node %N, pos %d, newpred %N)\n", block, pos, newpred));

        block_arity = get_irn_arity(block);

        NEW_ARR_A(ir_node*, ins, block_arity + 1);

        for (i = 0; i < block_arity; ++i) {
                ins[i] = get_irn_n(block, i);
        }
        ins[block_arity] = newpred;

        set_irn_in(block, block_arity + 1, ins);

#if 0
        block_arity = get_irn_arity(block);

        NEW_ARR_A(ir_node*, ins, block_arity - 1);

        for (i = 0; i < block_arity - 1; ++i) {
                ins[i] = get_irn_n(block, i);
        }

        set_irn_in(block, block_arity - 1, ins);
#endif

#if 0
        for_each_phi(block, phi) {
                int phi_arity = get_irn_arity(phi);
                DB((dbg, LEVEL_5, "duplicate_preds: fixing phi %N\n", phi)));

                NEW_ARR_A(ir_node *, ins, block_arity + 1);
                for (i = 0; i < phi_arity; ++i) {
                        DB((dbg, LEVEL_5, "in %N\n", get_irn_n(phi, i))));
                        ins[i] = get_irn_n(phi, i);
                }
                ins[block_arity] = get_copy(get_irn_n(phi, pos));
                set_irn_in(phi, block_arity + 1, ins);
        }
#endif
        return block_arity;
}

/**
 * Finds loop head and loop_info.
 */
static void get_loop_info(ir_node *node, void *env)
{
        unsigned node_in_loop, pred_in_loop;
        int i, arity;
        (void) env;

        arity = get_irn_arity(node);
        for (i = 0; i < arity; i++) {
                ir_node *pred = get_irn_n(node, i);

                pred_in_loop = is_in_loop(pred);
                node_in_loop = is_in_loop(node);

                /* collect some loop information */
                if (node_in_loop) {
                        if (is_Call(node))
                                ++loop_info.calls;
                }

                /* Find the loops head/the blocks with cfpred outside of the loop */
                if (is_Block(node) && node_in_loop && !pred_in_loop && loop_cf_head_valid) {
                        ir_node *cfgpred = get_Block_cfgpred(node, i);

                        if (!is_in_loop(cfgpred)) {
                                DB((dbg, LEVEL_5, "potential head %+F because inloop and pred %+F not inloop\n", node, pred));
                                /* another head? We do not touch this. */
                                if (loop_cf_head && loop_cf_head != node) {
                                        loop_cf_head_valid = 0;
                                } else {
                                        loop_cf_head = node;
                                }
                        }
                }
        }
}

/* Adds all nodes pointing into the loop to loop_entries and also finds the loops head */
static void get_loop_outs(ir_node *node, void *env)
{
        unsigned node_in_loop, pred_in_loop;
        int i, arity;
        (void) env;

        arity = get_irn_arity(node);
        for (i = 0; i < arity; ++i) {
                ir_node *pred = get_irn_n(node, i);

                pred_in_loop = is_in_loop(pred);
                node_in_loop = is_in_loop(node);

                if (pred_in_loop && !node_in_loop) {
                        out_edge entry;
                        entry.node = node;
                        entry.pred_irn_n = i;
                        ARR_APP1(out_edge, cur_loop_outs, entry);
                }
        }
}

static ir_node *ssa_second_def;
static ir_node *ssa_second_def_block;

/**
 * Walks the graph bottom up, searching for definitions and creates phis.
 */
static ir_node *search_def_and_create_phis(ir_node *block, ir_mode *mode)
{
        int i;
        int n_cfgpreds;
        ir_graph *irg;
        ir_node *phi;
        ir_node **in;

        DB((dbg, LEVEL_5, "ssa search_def_and_create_phis: block %N\n", block));

        /* Prevents creation of phi that would be bad anyway.
         * Dead and bad blocks. */
        if (get_irn_arity(block) < 1 || is_Bad(block))
                return new_Bad();

        if (block == ssa_second_def_block) {
                DB((dbg, LEVEL_5, "ssa found second definition: use second def %N\n", ssa_second_def));
                return ssa_second_def;
        }

        /* already processed this block? */
        if (irn_visited(block)) {
                ir_node *value = get_link(block);
                DB((dbg, LEVEL_5, "ssa already visited: use linked %N\n", value));
                return value;
        }

        irg = get_irn_irg(block);
        assert(block != get_irg_start_block(irg));

        /* a Block with only 1 predecessor needs no Phi */
        n_cfgpreds = get_Block_n_cfgpreds(block);
        if (n_cfgpreds == 1) {
                ir_node *pred_block = get_Block_cfgpred_block(block, 0);
                ir_node *value;

                DB((dbg, LEVEL_5, "ssa 1 pred: walk pred %N\n", pred_block));

                value = search_def_and_create_phis(pred_block, mode);
                set_link(block, value);
                mark_irn_visited(block);

                return value;
        }

        /* create a new Phi */
        NEW_ARR_A(ir_node*, in, n_cfgpreds);
        for (i = 0; i < n_cfgpreds; ++i)
                in[i] = new_Unknown(mode);

        phi = new_r_Phi(block, n_cfgpreds, in, mode);

        /* Important: always keep block phi list up to date. */
        add_Block_phi(block, phi);
        /* EVERY node is assumed to have a node_info linked. */
        alloc_node_info(phi, NULL);

        DB((dbg, LEVEL_5, "ssa phi creation: link new phi %N to block %N\n", phi, block));

        set_link(block, phi);
        mark_irn_visited(block);

        /* set Phi predecessors */
        for (i = 0; i < n_cfgpreds; ++i) {
                ir_node *pred_val;
                ir_node *pred_block = get_Block_cfgpred_block(block, i);
                assert(pred_block != NULL);
                pred_val = search_def_and_create_phis(pred_block, mode);
                assert(pred_val != NULL);

                DB((dbg, LEVEL_5, "ssa phi pred:phi %N, pred %N\n", phi, pred_val));
                set_irn_n(phi, i, pred_val);
        }
        return phi;
}

/**
 * Given a set of values this function constructs SSA-form for the users of the
 * first value (the users are determined through the out-edges of the value).
 * Works without using the dominance tree.
 */
static void construct_ssa(ir_node *orig_block, ir_node *orig_val,
                          ir_node *second_block, ir_node *second_val)
{
        ir_graph *irg;
        ir_mode *mode;
        const ir_edge_t *edge;
        const ir_edge_t *next;

        assert(orig_block && orig_val && second_block && second_val &&
                        "no parameter of construct_ssa may be NULL");

        /* no need to do anything */
        if (orig_val == second_val)
                return;

        irg = get_irn_irg(orig_val);

        ir_reserve_resources(irg, IR_RESOURCE_IRN_VISITED);
        inc_irg_visited(irg);

        mode = get_irn_mode(orig_val);
        set_link(orig_block, orig_val);
        mark_irn_visited(orig_block);

        ssa_second_def_block = second_block;
        ssa_second_def       = second_val;

        /* Only fix the users of the first, i.e. the original node */
        foreach_out_edge_safe(orig_val, edge, next) {
                ir_node *user = get_edge_src_irn(edge);
                int j = get_edge_src_pos(edge);
                ir_node *user_block = get_nodes_block(user);
                ir_node *newval;

                /* ignore keeps */
                if (is_End(user))
                        continue;

                DB((dbg, LEVEL_5, "original user %N\n", user));

                if (is_Phi(user)) {
                        ir_node *pred_block = get_Block_cfgpred_block(user_block, j);
                        newval = search_def_and_create_phis(pred_block, mode);
                } else {
                        newval = search_def_and_create_phis(user_block, mode);
                }

                /* If we get a bad node the user keeps the original in. No second definition needed. */
                if (newval != user && !is_Bad(newval))
                        set_irn_n(user, j, newval);
        }

        ir_free_resources(irg, IR_RESOURCE_IRN_VISITED);
}

/*
 * Construct SSA for def and all of its copies.
 */
static void construct_ssa_n(ir_node *def, ir_node *user)
{
        ir_graph *irg;
        ir_mode *mode;
        ir_node *iter = def;
        const ir_edge_t *edge;
        const ir_edge_t *next;
        irg = get_irn_irg(def);

        ir_reserve_resources(irg, IR_RESOURCE_IRN_VISITED);
        inc_irg_visited(irg);

        mode = get_irn_mode(def);

        for_each_copy(iter) {
                set_link(get_nodes_block(iter), iter);
                mark_irn_visited(get_nodes_block(iter));

                DB((dbg, LEVEL_5, "ssa_n:  Link def %N to block %N\n",
                                                                        iter, get_nodes_block(iter)));
        }

        /* Need to search the outs, because we need the in-pos on the user node. */
        foreach_out_edge_safe(def, edge, next) {
                ir_node *edge_user = get_edge_src_irn(edge);
                int edge_src = get_edge_src_pos(edge);
                ir_node *user_block = get_nodes_block(user);
                ir_node *newval;

                if (edge_user != user)
                        continue;

                if (is_Phi(user)) {
                        ir_node *pred_block = get_Block_cfgpred_block(user_block, edge_src);
                        newval = search_def_and_create_phis(pred_block, mode);
                } else {
                        newval = search_def_and_create_phis(user_block, mode);
                }

                if (newval != user && !is_Bad(newval))
                        set_irn_n(user, edge_src, newval);
        }

        ir_free_resources(irg, IR_RESOURCE_IRN_VISITED);
}

/**
 * Construct SSA for all definitions in arr.
 */
void construct_ssa_foreach(ir_node **arr, int arr_n)
{
        int i;
        for (i = 0; i < arr_n ; ++i) {
                ir_node *cppred, *block, *cpblock, *pred;

                pred = arr[i];
                cppred = get_copy(pred);
                block = get_nodes_block(pred);
                cpblock = get_nodes_block(cppred);
                construct_ssa(block, pred, cpblock, cppred);
        }
}

/* get the number of backedges without alien bes */
static int get_backedge_n(ir_node *loophead, unsigned with_alien)
{
        int i;
        int be_n = 0;
        int arity = get_irn_arity(loophead);
        for (i = 0; i < arity; ++i) {
                ir_node *pred = get_irn_n(loophead, i);
                if (is_backedge(loophead, i) && (with_alien || is_in_loop(pred)))
                        ++be_n;
        }
        return be_n;
}

/**
 * Rewires the heads after peeling.
 */
static void peel_fix_heads(void)
{
        ir_node **loopheadnins, **peelheadnins;
        ir_node *loophead = loop_cf_head;
        ir_node *peelhead = get_copy(loophead);

        int headarity = get_irn_arity(loophead);
        ir_node *phi;
        int i;

        int lheadin_c = 0;
        int pheadin_c = 0;

        int backedges_n = get_backedge_n(loophead, 0);

        int lhead_arity = 2 * backedges_n;
        int phead_arity = headarity - backedges_n;

        /* new in arrays */
        NEW_ARR_A(ir_node *, loopheadnins, lhead_arity );
        NEW_ARR_A(ir_node *, peelheadnins, phead_arity );

        for_each_phi(loophead, phi) {
                NEW_ARR_A(ir_node *, get_node_info(phi)->ins, lhead_arity);
        }
        for_each_phi(peelhead, phi) {
                NEW_ARR_A(ir_node *, get_node_info(phi)->ins, phead_arity);
        }

        for (i = 0; i < headarity; i++)
        {
                ir_node *orgjmp = get_irn_n(loophead, i);
                ir_node *copyjmp = get_copy(orgjmp);

                /**
                 * Rewire the head blocks ins and their phi ins.
                 * Requires phi list per block.
                 */
                if (is_backedge(loophead, i) && !is_alien_edge(loophead, i)) {
                        loopheadnins[lheadin_c] = orgjmp;
                        for_each_phi(loophead, phi) {
                                get_node_info( phi )->ins[lheadin_c] =  get_irn_n( phi, i) ;
                        }
                        ++lheadin_c;

                        /* former bes of the peeled code origin now from the loophead */
                        loopheadnins[lheadin_c] = copyjmp;

                        /* get_irn_n( get_copy_of(phi), i ) <!=> get_copy_of( get_irn_n( phi, i) )
                         * Order is crucial! Predecessors outside of the loop are non existent.
                         * The copy (cloned with its ins!) has pred i,
                         * but phis pred i might not have a copy of itself.
                         */
                        for_each_phi(loophead, phi) {
                                get_node_info( phi )->ins[lheadin_c] =  get_irn_n( get_copy(phi), i) ;
                        }
                        ++lheadin_c;
                } else {
                        peelheadnins[pheadin_c] = orgjmp;
                        for_each_phi(peelhead, phi) {
                                get_node_info( phi )->ins[pheadin_c] = get_irn_n(phi, i);
                        }
                        ++pheadin_c;
                }
        }/* for */

        assert(pheadin_c == ARR_LEN(peelheadnins) &&
                        lheadin_c == ARR_LEN(loopheadnins) &&
                        "the constructed head arities do not match the predefined arities");

        /* assign the ins to the nodes */
        set_irn_in(loophead, ARR_LEN(loopheadnins), loopheadnins);
        set_irn_in(peelhead, ARR_LEN(peelheadnins), peelheadnins);

        for_each_phi(loophead, phi) {
                ir_node **ins = get_node_info( phi )->ins;
                set_irn_in(phi, lhead_arity, ins);
        }

        for_each_phi(peelhead, phi) {
                ir_node **ins = get_node_info( phi )->ins;
                set_irn_in(phi, phead_arity, ins);
        }
}

/**
 * Create a raw copy (ins are still the old ones) of the given node.
 * We rely on copies to be NOT visited.
 */
static ir_node *rawcopy_node(ir_node *node)
{
        int i, arity;
        ir_node *cp;
        node_info *cpstate;

        cp = exact_copy(node);

        arity = get_irn_arity(node);

        /* FIX remove */
        set_irn_in(cp, arity, get_irn_in(node));

        for (i = 0; i < arity; ++i) {
                if (is_backedge(node, i))
                        set_backedge(cp, i);
        }

        set_copy(node, cp);
        cpstate = new_node_info();
        set_irn_link(cp, cpstate);


        if (is_Block(cp)) {
                /* TODO
                 * exact_copy already sets Macroblock.
                 * Why should we do this anyway? */
                set_Block_MacroBlock(cp, cp);
        }

        return cp;
}

/**
 * This walker copies all walked nodes.
 * If the walk_condition is true for a node, it is walked.
 * All nodes node_info->copy attributes have to be NULL prior to every walk.
 */
static void copy_walk(ir_node *node, walker_condition *walk_condition, ir_loop *set_loop)
{
        int i;
        int arity;
        ir_node *cp;
        ir_node **cpin;
        ir_graph *irg = current_ir_graph;
        node_info *node_info = get_node_info(node);

        /**
         * break condition and cycle resolver, creating temporary node copies
         */
        if (get_irn_visited(node) >= get_irg_visited(irg)) {
                /* Here we rely on nodestate's copy being initialized with NULL */
                DB((dbg, LEVEL_5, "copy_walk: We have already visited %N\n", node));
                if (node_info->copy == NULL) {
                        cp = rawcopy_node(node);
                        DB((dbg, LEVEL_5, "The TEMP copy of %N is created %N\n", node, cp));
                }
                return;
        }

        /* Walk */
        mark_irn_visited(node);

        if (!is_Block(node)) {
                ir_node *pred = get_nodes_block(node);
                if (walk_condition(pred))
                        DB((dbg, LEVEL_5, "walk block %N\n", pred));
                        copy_walk(pred, walk_condition, set_loop);
        }

        arity = get_irn_arity(node);

        NEW_ARR_A(ir_node *, cpin, arity);

        for (i = 0; i < arity; ++i) {
                ir_node *pred = get_irn_n(node, i);

                if (walk_condition(pred)) {
                        DB((dbg, LEVEL_5, "walk node %N\n", pred));
                        copy_walk(pred, walk_condition, set_loop);
                        cpin[i] = get_copy(pred);
                        DB((dbg, LEVEL_5, "copy of %N gets new in %N which is copy of %N\n",
                                node, get_copy(pred), pred));
                } else {
                        cpin[i] = pred;
                }
        }

        /* copy node / finalize temp node */
        if (node_info->copy == NULL) {
                /* No temporary copy existent */
                cp = rawcopy_node(node);
                DB((dbg, LEVEL_5, "The FINAL copy of %N is CREATED %N\n", node, cp));
        } else {
                /* temporary copy is existent but without correct ins */
                cp = get_copy(node);
                DB((dbg, LEVEL_5, "The FINAL copy of %N is EXISTENT %N\n", node, cp));
        }

        if (!is_Block(node)) {
                ir_node *cpblock = get_copy(get_nodes_block(node));

                set_nodes_block(cp, cpblock );
                if (is_Phi(cp))
                        add_Block_phi(cpblock, cp);
        }

        set_irn_loop(cp, set_loop);
        set_irn_in(cp, ARR_LEN(cpin), cpin);
}

/**
 * Loop peeling, and fix the cf for the loop entry nodes, which have now more preds
 */
static void peel(out_edge *loop_outs)
{
        int i;
        ir_node **entry_buffer;
        int entry_c = 0;

        ir_reserve_resources(current_ir_graph, IR_RESOURCE_IRN_VISITED);

        NEW_ARR_A(ir_node *, entry_buffer, ARR_LEN(loop_outs));

        /* duplicate loop walk */
        inc_irg_visited(current_ir_graph);

        for (i = 0; i < ARR_LEN(loop_outs); i++) {
                out_edge entry = loop_outs[i];
                ir_node *node = entry.node;
                ir_node *pred = get_irn_n(entry.node, entry.pred_irn_n);

                if (is_Block(node)) {
                        copy_walk(pred, is_in_loop, NULL);
                        duplicate_preds(node, entry.pred_irn_n, get_copy(pred) );
                } else {
                        copy_walk(pred, is_in_loop, NULL);
                        /* leave out keepalives */
                        if (!is_End(node)) {
                                /* Node is user of a value defined inside the loop.
                                 * We'll need a phi since we duplicated the loop. */
                                /* Cannot construct_ssa here, because it needs another walker. */
                                entry_buffer[entry_c] = pred;
                                ++entry_c;
                        }
                }
        }

        ir_free_resources(current_ir_graph, IR_RESOURCE_IRN_VISITED);

        /* Rewires the 2 heads */
        peel_fix_heads();

        /* Generate phis for values from peeled code and original loop */
        construct_ssa_foreach(entry_buffer, entry_c);
        /*for (i = 0; i < entry_c; i++)
        {
                ir_node *cppred, *block, *cpblock, *pred;

                pred = entry_buffer[i];
                cppred = get_copy(pred);
                block = get_nodes_block(pred);
                cpblock = get_nodes_block(cppred);
                construct_ssa(block, pred, cpblock, cppred);
        }*/
}

/**
 * Populates head_entries with (node, pred_pos) tuple
 * whereas the node's pred at pred_pos is in the head but not the node itself.
 * Head and condition chain blocks must be marked.
 */
static void get_head_outs(ir_node *node, void *env)
{
        int i;
        int arity = get_irn_arity(node);
        (void) env;

        DB((dbg, LEVEL_5, "get head entries %N \n", node));

        for (i = 0; i < arity; ++i) {
                /* node is not in the head, but the predecessor is.
                 * (head or loop chain nodes are marked) */

                DB((dbg, LEVEL_5, "... "));
                DB((dbg, LEVEL_5, "node %N  marked %d (0)  pred %d marked %d (1) \n",
                    node->node_nr, is_nodesblock_marked(node),i, is_nodesblock_marked(get_irn_n(node, i))));

                if (!is_nodesblock_marked(node) && is_nodesblock_marked(get_irn_n(node, i))) {
                        out_edge entry;
                        entry.node = node;
                        entry.pred_irn_n = i;
                        DB((dbg, LEVEL_5,
                                "Found head chain entry %N @%d because !inloop %N and inloop %N\n",
                                node, i, node, get_irn_n(node, i)));
                        ARR_APP1(out_edge, cur_head_outs, entry);
                }
        }
}

/**
 * Find condition chains, and add them to be inverted, until the node count exceeds the limit.
 * A block belongs to the chain if a condition branches out of the loop.
 * Returns 1 if the given block belongs to the condition chain.
 */
static unsigned find_condition_chains(ir_node *block)
{
        const ir_edge_t *edge;
        unsigned mark = 0;
        int nodes_n = 0;

        DB((dbg, LEVEL_5, "condition_chains for block %N\n", block));

        /* Collect all outs, including keeps.
         * (TODO firm function for number of out edges?) */
        foreach_out_edge_kind(block, edge, EDGE_KIND_NORMAL) {
                ++nodes_n;
        }

        /* We do not want to collect more nodes from condition chains, than the limit allows us to.
         * Also, leave at least one block as body. */
        if (head_inversion_node_count + nodes_n > inversion_head_node_limit
                    || head_inversion_block_count + 1 == loop_info.blocks) {
                set_Block_mark(block, 0);

                return 0;
        }

        /* First: check our successors, and add all succs that are outside of the loop to the list */
        foreach_block_succ(block, edge) {
                ir_node *src = get_edge_src_irn( edge );
                int pos = get_edge_src_pos( edge );

                if (!is_in_loop(src)) {
                        out_edge entry;

                        mark = 1;
                        entry.node = src;
                        entry.pred_irn_n = pos;
                        ARR_APP1(out_edge, cond_chain_entries, entry);
                        mark_irn_visited(src);
                }
        }

        if (mark == 0) {
                /* this block is not part of the chain,
                 * because the chain would become too long or we have no successor outside of the loop */

                set_Block_mark(block, 0);
                return 0;
        } else {
                set_Block_mark(block, 1);
                ++head_inversion_block_count;
                DB((dbg, LEVEL_5, "block %N is part of condition chain\n", block));
                head_inversion_node_count += nodes_n;
        }

        /* Second: walk all successors, and add them to the list if they are not part of the chain */
        foreach_block_succ(block, edge) {
                unsigned inchain;
                ir_node *src = get_edge_src_irn( edge );
                int pos = get_edge_src_pos( edge );

                /* already done cases */
                if (!is_in_loop( src ) || (get_irn_visited(src) >= get_irg_visited(current_ir_graph))) {
                        continue;
                }

                mark_irn_visited(src);
                DB((dbg, LEVEL_5, "condition chain walk %N\n", src));
                inchain = find_condition_chains(src);

                /* if successor is not part of chain we need to collect its outs */
                if (!inchain) {
                        out_edge entry;
                        entry.node = src;
                        entry.pred_irn_n = pos;
                        ARR_APP1(out_edge, cond_chain_entries, entry);
                }
        }
        return mark;
}

/**
 * Rewire the loop head and inverted head for loop inversion.
 */
static void inversion_fix_heads(void)
{
        ir_node **loopheadnins, **invheadnins;
        ir_node *loophead = loop_cf_head;
        ir_node *invhead =      get_copy(loophead);

        int headarity =         get_irn_arity(loophead);
        ir_node *phi;
        int i;

        int lheadin_c = 0;
        int iheadin_c = 0;

        int backedges_n = get_backedge_n(loophead, 0);
        int lhead_arity = backedges_n;
        int ihead_arity = headarity - backedges_n;

        assert(lhead_arity != 0 && "Loophead has arity 0. Probably wrong backedge informations.");
        assert(ihead_arity != 0 && "Inversionhead has arity 0. Probably wrong backedge informations.");

        /* new in arrays for all phis in the head blocks */
        NEW_ARR_A(ir_node *, loopheadnins, lhead_arity);
        NEW_ARR_A(ir_node *, invheadnins, ihead_arity);

        for_each_phi(loophead, phi) {
                NEW_ARR_A(ir_node *, get_node_info(phi)->ins, lhead_arity);
        }
        for_each_phi(invhead, phi) {
                NEW_ARR_A(ir_node *, get_node_info(phi)->ins, ihead_arity);
        }

        for (i = 0; i < headarity; i++) {
                ir_node *pred = get_irn_n(loophead, i);

                /**
                 * Rewire the head blocks ins and their phi ins.
                 * Requires phi list per block.
                 */
                if (is_backedge(loophead, i) && !is_alien_edge(loophead, i)) {
                        /* just copy these edges */
                        loopheadnins[lheadin_c] = pred;
                        for_each_phi(loophead, phi) {
                                get_node_info(phi)->ins[lheadin_c] = get_irn_n(phi, i);
                        }
                        ++lheadin_c;
                } else {
                        invheadnins[iheadin_c] = pred;
                        for_each_phi(invhead, phi) {
                                get_node_info(phi)->ins[iheadin_c] = get_irn_n(phi, i) ;
                        }
                        ++iheadin_c;
                }
        }

        /* assign the ins to the head blocks */
        set_irn_in(loophead, ARR_LEN(loopheadnins), loopheadnins);
        set_irn_in(invhead, ARR_LEN(invheadnins), invheadnins);

        /* assign the ins for the phis */
        for_each_phi(loophead, phi) {
                ir_node **ins = get_node_info(phi)->ins;
                set_irn_in(phi, lhead_arity, ins);
        }

        for_each_phi(invhead, phi) {
                ir_node **ins = get_node_info(phi)->ins;
                set_irn_in(phi, ihead_arity, ins);
        }
}

static void inversion_walk(out_edge *head_entries)
{
        int i;
        ir_node *phi;
        int entry_c = 0;
        ir_node **entry_buffer;
        ir_node **head_phi_assign;

        NEW_ARR_A(ir_node *, entry_buffer, ARR_LEN(head_entries));

        head_phi_assign = NEW_ARR_F(ir_node *, 0);

        /* Find assignments in the condition chain,
         * to construct_ssa for them after the loop inversion. */
        for_each_phi(loop_cf_head , phi) {
                int arity = get_irn_arity(phi);
                for (i = 0; i < arity; ++i) {
                        ir_node *def = get_irn_n(phi, i);
                        if (is_nodesblock_marked(def)) {
                                ARR_APP1(ir_node *, head_phi_assign, def);
                        }
                }
        }

        ir_reserve_resources(current_ir_graph, IR_RESOURCE_IRN_VISITED);

        /**
         * duplicate condition chain
         **/
        inc_irg_visited(current_ir_graph);

        for (i = 0; i < ARR_LEN(head_entries); ++i) {
                out_edge entry = head_entries[i];
                ir_node *node = entry.node;
                ir_node *pred = get_irn_n(entry.node, entry.pred_irn_n);

                if (is_Block(node)) {
                        DB((dbg, LEVEL_5, "\nInit walk block %N\n", pred));

                        copy_walk(pred, is_nodesblock_marked, cur_loop);
                        duplicate_preds(node, entry.pred_irn_n, get_copy(pred) );
                } else {
                        DB((dbg, LEVEL_5, "\nInit walk node  %N\n", pred));

                        copy_walk(pred, is_nodesblock_marked, cur_loop);

                        /* ignore keepalives */
                        if (!is_End(node)) {
                                /* Node is user of a value assigned inside the loop.
                                 * We will need a phi since we duplicated the head. */
                                entry_buffer[entry_c] = pred;
                                ++entry_c;
                        }
                }
        }

        ir_free_resources(current_ir_graph, IR_RESOURCE_IRN_VISITED);

        inversion_fix_heads();

        /* Generate phis for users of values assigned in the condition chain
         * and read in the loops body */
        construct_ssa_foreach(entry_buffer, entry_c);

        /* Generate phis for values that are assigned in the condition chain
         * but not read in the loops body. */
        construct_ssa_foreach(head_phi_assign, ARR_LEN(head_phi_assign));

        loop_cf_head = get_copy(loop_cf_head);
}

/* Loop peeling */
void loop_peeling(void)
{
        cur_loop_outs = NEW_ARR_F(out_edge, 0);
        irg_walk_graph( current_ir_graph, get_loop_outs, NULL, NULL );

        peel(cur_loop_outs);

        /* clean up */
        reset_node_infos();

        set_irg_doms_inconsistent(current_ir_graph);
        set_irg_loopinfo_inconsistent(current_ir_graph);
        set_irg_outs_inconsistent(current_ir_graph);

        DEL_ARR_F(cur_loop_outs);
}

/* Loop inversion */
void loop_inversion(void)
{
        unsigned do_inversion = 1;

        inversion_head_node_limit = INT_MAX;

        /* Search for condition chains. */
        ir_reserve_resources(current_ir_graph, IR_RESOURCE_BLOCK_MARK);

        irg_walk_graph(current_ir_graph, reset_block_mark, NULL, NULL);

        loop_info.blocks = get_loop_n_blocks(cur_loop);
        cond_chain_entries = NEW_ARR_F(out_edge, 0);

        head_inversion_node_count = 0;
        head_inversion_block_count = 0;

        set_Block_mark(loop_cf_head, 1);
        mark_irn_visited(loop_cf_head);
        inc_irg_visited(current_ir_graph);

        find_condition_chains(loop_cf_head);

        DB((dbg, LEVEL_3, "Loop contains %d blocks.\n", loop_info.blocks));
        if (loop_info.blocks < 2) {
                do_inversion = 0;
                DB((dbg, LEVEL_3, "Loop contains %d (less than 2) blocks => No Inversion done.\n", loop_info.blocks));
        }

        /* We also catch endless loops here,
         * because they do not have a condition chain. */
        if (head_inversion_block_count < 1) {
                do_inversion = 0;
                DB((dbg, LEVEL_3, "Loop contains %d (less than 1) invertible blocks => No Inversion done.\n", head_inversion_block_count));
        }

        if (do_inversion) {
                cur_head_outs = NEW_ARR_F(out_edge, 0);

                /* Get all edges pointing into the head or condition chain (outs). */
                irg_walk_graph(current_ir_graph, get_head_outs, NULL, NULL);
                inversion_walk(cur_head_outs);

                DEL_ARR_F(cur_head_outs);

                set_irg_doms_inconsistent(current_ir_graph);
                set_irg_loopinfo_inconsistent(current_ir_graph);
                set_irg_outs_inconsistent(current_ir_graph);
        }

        /* free */
        DEL_ARR_F(cond_chain_entries);
        ir_free_resources(current_ir_graph, IR_RESOURCE_BLOCK_MARK);
}

/**
 * Returns last element of linked list of copies by
 * walking the linked list.
 */
ir_node *get_last_copy(ir_node *node)
{
        ir_node *copy, *cur;
        cur = node;
        while ((copy = get_copy(cur))) {
                cur = copy;
        }
        return cur;
}

/**
 * Rewire floating copies of the current loop.
 */
void unrolling_fix_cf(void)
{
        ir_node *loophead = loop_cf_head;
        int headarity =         get_irn_arity(loophead);
        ir_node *phi, *headnode;
        /*ir_node *high, *low;*/
        int i;

        int uhead_in_n = 0;
        int backedges_n = get_backedge_n(loophead, 0);
        int unroll_arity = backedges_n;

        /* Create ins for all heads and their phis */
        headnode = get_copy(loophead);
        for_each_copy(headnode) {
                NEW_ARR_A(ir_node *, get_node_info(headnode)->ins, unroll_arity);
                for_each_phi(headnode, phi) {
                        NEW_ARR_A(ir_node *, get_node_info(phi)->ins, unroll_arity);
                }
        }

        /* Append the copies to the existing loop. */
        for (i = 0; i < headarity; i++) {
                ir_node *upper_head = loophead;
                ir_node *lower_head = get_copy(loophead);

                ir_node *upper_pred = get_irn_n(loophead, i);
                ir_node *lower_pred = get_copy(get_irn_n(loophead, i));

                ir_node *last_pred;

                /**
                 * Build unrolled loop top down
                 */
                if (is_backedge(loophead, i) && !is_alien_edge(loophead, i)) {
                        for_each_copy2(upper_head, lower_head, upper_pred, lower_pred) {
                                get_node_info(lower_head)->ins[uhead_in_n] = upper_pred;

                                for_each_phi(upper_head, phi) {
                                        ir_node *phi_copy = get_copy(phi);
                                        get_node_info(phi_copy)->ins[uhead_in_n] = get_irn_n(phi, i);
                                }
                        }

                        last_pred = upper_pred;
                        ++uhead_in_n;

                        /* Fix the topmost loop heads backedges. */
                        set_irn_n(loophead, i, last_pred);
                        for_each_phi(loophead, phi) {
                                ir_node *last_phi = get_last_copy(phi);
                                ir_node *pred = get_irn_n(last_phi, i);
                                set_irn_n(phi, i, pred);
                        }
                }
        }

        headnode = get_copy(loophead);
        for_each_copy(headnode) {
                set_irn_in(headnode, unroll_arity, get_node_info(headnode)->ins);
                for_each_phi(headnode, phi) {
                        set_irn_in(phi, unroll_arity, get_node_info(phi)->ins);
                }
        }
}

#if 0
static ir_node *add_phi(ir_node *node, int phi_pos)
{
        ir_mode *mode;
        ir_node *phi;
        ir_node **in;
        mode = get_irn_mode(get_irn_n(node, phi_pos));
        ir_node *block = get_nodes_block(node);
        int n_cfgpreds = get_irn_arity(block);
        ir_node *pred = get_irn_n(node, phi_pos);
        int i;

        /* create a new Phi */
        NEW_ARR_A(ir_node*, in, n_cfgpreds);
        for (i = 0; i < n_cfgpreds; ++i)
                in[i] = new_Unknown(mode);  /*pred;*/

        phi = new_r_Phi(block, n_cfgpreds, in, mode);

        assert(phi && "phi null");
        assert(is_Bad(phi) && "phi bad");

        /* Important: always keep block phi list up to date. */
        add_Block_phi(block, phi);
        /* EVERY node is assumed to have a node_info linked. */
        alloc_node_info(phi, NULL);

        set_irn_n(node, phi_pos, phi);
        return phi;
}
#endif


/**
 * Loop unrolling
 * Could be improved with variable range informations.
 */
void loop_unrolling(void)
{
        int i, j;

        unroll_times = 7;

        cur_loop_outs = NEW_ARR_F(out_edge, 0);
        irg_walk_graph( current_ir_graph, get_loop_outs, NULL, NULL );

        ir_reserve_resources(current_ir_graph, IR_RESOURCE_IRN_VISITED);

        /* duplicate whole loop content */
        inc_irg_visited(current_ir_graph);

        for (i = 0; i < ARR_LEN(cur_loop_outs); ++i) {
                out_edge entry = cur_loop_outs[i];
                ir_node *node = entry.node;
                ir_node *pred = get_irn_n(entry.node, entry.pred_irn_n);

                for (j = 0; j < unroll_times - 1; ++j) {
                        copy_walk(pred, is_in_loop, cur_loop);
                        if (is_Block(node)) {
                                duplicate_preds(node, entry.pred_irn_n, get_copy(pred));
                        }
                        pred = get_copy(pred);
                }
        }

        ir_free_resources(current_ir_graph, IR_RESOURCE_IRN_VISITED);

        /* Line up the floating copies. */
        unrolling_fix_cf();

        /* Generate phis for all loop outs */
        for (i = 0; i < ARR_LEN(cur_loop_outs); ++i) {
                out_edge entry = cur_loop_outs[i];
                ir_node *node = entry.node;
                ir_node *pred = get_irn_n(entry.node, entry.pred_irn_n);

                if (!is_Block(node) && !is_End(node)) {
                        DB((dbg, LEVEL_5, "  construct_ssa_n def %N  node %N  pos %d\n",
                                        pred, node, entry.pred_irn_n));
                        construct_ssa_n(pred, node);
                }
        }

        DEL_ARR_F(cur_loop_outs);

        set_irg_doms_inconsistent(current_ir_graph);
        set_irg_loopinfo_inconsistent(current_ir_graph);
        set_irg_outs_inconsistent(current_ir_graph);
}

/* Initialization and */
static void init_analyze(ir_loop *loop)
{
        /* Init new for every loop */
        cur_loop = loop;

        loop_cf_head = NULL;
        loop_cf_head_valid = 1;
        loop_inv_head = NULL;
        loop_peeled_head = NULL;

        loop_info.outs = 0;
        loop_info.calls = 0;
        loop_info.loads = 0;
        loop_info.blocks = 0;

        DB((dbg, LEVEL_2, "  >>>> current loop includes node %N <<<\n", get_loop_node(loop, 0)));

        irg_walk_graph(current_ir_graph, get_loop_info, NULL, NULL);

        /* RETURN if there is no valid head */
        if (!loop_cf_head || !loop_cf_head_valid) {
                DB((dbg, LEVEL_2,   "No valid loop head. Nothing done.\n"));
                return;
        }

        if (enable_peeling)
                loop_peeling();

        if (enable_inversion)
                loop_inversion();
        if (enable_unrolling)
                loop_unrolling();

#if 0
        /* RETURN if there is a call in the loop */
        if (loop_info.calls)
                return;
#endif

        DB((dbg, LEVEL_2, "      <<<< end of loop with node %N >>>>\n", get_loop_node(loop, 0)));
}

/* Find most inner loops and send them to analyze_loop */
static void find_most_inner_loop(ir_loop *loop)
{
        /* descend into sons */
        int sons = get_loop_n_sons(loop);

        if (sons == 0) {
                loop_element elem;
                int el_n, i;

                el_n = get_loop_n_elements(loop);

                for (i=0; i < el_n; ++i) {
                        elem = get_loop_element(loop, i);
                        /* We can only rely on the blocks,
                         * as the loop attribute of the nodes seems not to be set. */
                        if (is_ir_node(elem.kind) && is_Block(elem.node)) {
                                ARR_APP1(ir_node *, loops, elem.node);
                                DB((dbg, LEVEL_5, "Found most inner loop (contains block %+F)\n", elem.node));
                                break;
                        }
                }
        } else {
                int s;
                for (s=0; s<sons; s++) {
                        find_most_inner_loop(get_loop_son(loop, s));
                }
        }
}

/**
 * Assure preconditions are met and go through all loops.
 */
void loop_optimization(ir_graph *irg)
{
        ir_loop *loop;
        int     i, sons, nr;

        /* Init */
        link_node_state_list = NULL;
        set_current_ir_graph(irg);

        /* preconditions */
        edges_assure(irg);
        assure_irg_outs(irg);

        /* NOTE: sets only the loop attribute of blocks, not nodes */
        /* NOTE: Kills links */
        assure_cf_loop(irg);

        ir_reserve_resources(irg, IR_RESOURCE_IRN_LINK|IR_RESOURCE_PHI_LIST);
        collect_phiprojs(irg);
        ir_free_resources(irg, IR_RESOURCE_IRN_LINK);

        /* allocate node_info for additional information on nodes */
        ir_reserve_resources(irg, IR_RESOURCE_IRN_LINK);
        irg_walk_graph(current_ir_graph, alloc_node_info, NULL, NULL);

        loop = get_irg_loop(irg);
        sons = get_loop_n_sons(loop);

        loops = NEW_ARR_F(ir_node *, 0);

        for (nr = 0; nr < sons; ++nr) {
                find_most_inner_loop(get_loop_son(loop, nr));
        }

/* TODO Keep backedges during optimization to avoid
 * this ugly allocation and deallocation.
 * (set_irn_in seems to destroy them)
 */
#if 0
        for (i = 0; i < ARR_LEN(loops); ++i) {
                ir_loop *loop;

                loop = get_irn_loop(loops[i]);
                init_analyze(loop);
        }
#else
        /* This part is useful for testing
         * or has to be used if the backedge information is destroyed.
         * Which is the case at the moment, because the backedge information gets lost
         * before inversion_fix_heads/unrolling_fix_cf, which results in bads.
         * NOTE!: Testsuite runs successfully nevertheless...
         */

        /**
         * assure_cf_loop() creates a completely new loop tree.
         * Thus we cannot optimize a loop, assure_cf_loop() and continue with the next loop,
         * as the next loop must be searched because it is not distinguishable from the
         * already done loops.
         * The links of the loops are also not available anymore (to store a "loop done" flag).
         * Therefore we save a block per loop.
         * NOTE: We rely on the loop optimizations not to remove any block from the loop.
         * Later, we fetch the blocks loop attribute, as it is updated by assure_cf_loop.
         */
        for (i = 0; i < ARR_LEN(loops); ++i) {
                ir_loop *loop;

                free_node_info();
                ir_free_resources(irg, IR_RESOURCE_IRN_LINK);

                edges_assure(current_ir_graph);
                assure_irg_outs(current_ir_graph);

                /* NOTE: sets only the loop attribute of blocks */
                /* NOTE: Kills links */
                assure_cf_loop(current_ir_graph);

                irg_walk_graph(current_ir_graph, alloc_node_info, NULL, NULL);
                ir_reserve_resources(irg, IR_RESOURCE_IRN_LINK);

                /* Get loop from block */
                loop = get_irn_loop(loops[i]);
                init_analyze(loop);
        }
#endif

        /* Free */
        DEL_ARR_F(loops);

        free_node_info();
        ir_free_resources(irg, IR_RESOURCE_IRN_LINK);
        ir_free_resources(irg, IR_RESOURCE_PHI_LIST);
}

void do_loop_unrolling(ir_graph *irg)
{
        enable_unrolling = 1;
        enable_peeling = 0;
        enable_inversion = 0;

        DB((dbg, LEVEL_2, " >>> unrolling (Startnode %N) <<<\n",
                get_irg_start(irg)));

        loop_optimization(irg);

        DB((dbg, LEVEL_2, " >>> unrolling done (Startnode %N) <<<\n",
                get_irg_start(irg)));
}

void do_loop_inversion(ir_graph *irg)
{
        enable_unrolling = 0;
        enable_peeling = 0;
        enable_inversion = 1;

        DB((dbg, LEVEL_2, " >>> inversion (Startnode %N) <<<\n",
                get_irg_start(irg)));

        loop_optimization(irg);

        DB((dbg, LEVEL_2, " >>> inversion done (Startnode %N) <<<\n",
                get_irg_start(irg)));
}

void do_loop_peeling(ir_graph *irg)
{
        enable_unrolling = 0;
        enable_peeling = 1;
        enable_inversion = 0;

        DB((dbg, LEVEL_2, " >>> peeling (Startnode %N) <<<\n",
                get_irg_start(irg)));

        loop_optimization(irg);

        DB((dbg, LEVEL_2, " >>> peeling done (Startnode %N) <<<\n",
                get_irg_start(irg)));

}

ir_graph_pass_t *loop_inversion_pass(const char *name)
{
        return def_graph_pass(name ? name : "loop_inversion", do_loop_inversion);
}

ir_graph_pass_t *loop_unroll_pass(const char *name)
{
        return def_graph_pass(name ? name : "loop_unroll", do_loop_unrolling);
}

ir_graph_pass_t *loop_peeling_pass(const char *name)
{
        return def_graph_pass(name ? name : "loop_peeling", do_loop_peeling);
}

void firm_init_loop_opt(void)
{
        FIRM_DBG_REGISTER(dbg, "firm.opt.loop");
}