[libfirm] / ir / be / becopyilp.c

/**
 * Author:      Daniel Grund
 * Date:                17.05.2005
 * Copyright:   (c) Universitaet Karlsruhe
 * Licence:     This file protected by GPL -  GNU GENERAL PUBLIC LICENSE.
 */
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#ifdef HAVE_ALLOCA_H
#include <alloca.h>
#endif
#ifdef HAVE_MALLOC_H
#include <malloc.h>
#endif

#include "lpp.h"
#include "xmalloc.h"
#include "becopyopt.h"
#include "becopystat.h"

#define DEBUG_LVL SET_LEVEL_1
static firm_dbg_module_t *dbg = NULL;

#define SLOTS_LIVING 32

/**
 * Represents the _costs_ if node n and m have different colors.
 * Must be >=0.
 **/
#define get_weight(n,m) 1

typedef struct _simpl_t {
        struct list_head chain;
        if_node_t *ifn;
} simpl_t;

typedef struct _problem_instance_t {
        const copy_opt_t *co;                   /** the original copy_opt problem */
        /* problem size reduction removing simple nodes */
        struct list_head simplicials;   /**< holds all simpl_t's in right order to color*/
        pset *removed;                                  /**< holds all removed simplicial irns */
        /* lp problem */
        lpp_t *dilp;                                    /**< problem formulation directly as milp */
        /* overhead stuff */
        lpp_t *curr_lp;                                 /**< points to the problem currently used */
        int curr_color, cst_counter, last_x_var;
        char buf[32];
} problem_instance_t;

#define is_removed(irn) pset_find_ptr(pi->removed, irn)
/*
 * Some stuff for variable name handling.
 */
#define mangle_cst(buf, prefix, nr) \
                        snprintf((buf), sizeof(buf), "%c%d", (prefix), (nr))

#define mangle_var(buf, prefix, node_nr, color) \
                        snprintf((buf), sizeof(buf), "%c%d_%d", (prefix), (node_nr), (color))

#define mangle_var_irn(buf, prefix, irn, color) \
                        mangle_var((buf), (prefix), get_irn_graph_nr(irn), (color))

#define split_var(var, nnr, col) \
                        sscanf(var, "x%d_%d", (nnr), (col))


/**
 * Checks if a node is simplicial in the graph
 * heeding the already removed nodes.
 */
static INLINE int pi_is_simplicial(problem_instance_t *pi, const if_node_t *ifn) {
        int i, o, size = 0;
        if_node_t **all, *curr;
        all = alloca(ifn_get_degree(ifn) * sizeof(*all));

        /* get all non-removed neighbors */
        foreach_neighb(ifn, curr)
                if (!is_removed(curr))
                        all[size++] = curr;

        /* check if these form a clique */
        for (i=0; i<size; ++i)
                for (o=i+1; o<size; ++o)
                        if (!ifg_has_edge(pi->co->chordal_env, all[i], all[o]))
                                return 0;

        /* all edges exist so this is a clique */
        return 1;
}

/**
 * Iterative finds and 'removes' from the graph all nodes which are
 * simplicial AND not member of a equal-color-wish
 */
static void pi_find_simplicials(problem_instance_t *pi) {
        set *if_nodes;
        if_node_t *ifn;
        int redo = 1;

        if_nodes = be_ra_get_ifg_nodes(pi->co->chordal_env);
        while (redo) {
                redo = 0;
                for (ifn = set_first(if_nodes); ifn; ifn = set_next(if_nodes)) {
                        ir_node *irn = get_irn_for_graph_nr(pi->co->irg, ifn->nnr);
                        if (!is_removed(irn) && !is_optimizable(irn) &&
          !is_optimizable_arg(pi->co, irn) && pi_is_simplicial(pi, ifn)) {
                                simpl_t *s = xmalloc(sizeof(*s));
                                s->ifn = ifn;
                                list_add(&s->chain, &pi->simplicials);
                                pset_insert_ptr(pi->removed, irn);
                                redo = 1;
                                DBG((dbg, LEVEL_2, " Removed %n\n", irn));
                        }
                }
        }
}

/**
 * Add coloring-force conditions
 */
static void pi_add_constr_A(ir_node *block, void *env) {
        problem_instance_t *pi = env;
        struct list_head *head = get_block_border_head(pi->co->chordal_env, block);
        border_t *curr;
        bitset_t *pos_regs = bitset_alloca(pi->co->cls->n_regs);

        list_for_each_entry_reverse(border_t, curr, head, list)
                if (curr->is_def && curr->is_real && !is_removed(curr->irn)) {
                        int cst_idx, nnr, col;

                        nnr = get_irn_graph_nr(curr->irn);
                        mangle_cst(pi->buf, 'A', nnr);
                        cst_idx = lpp_add_cst(pi->curr_lp, pi->buf, equal, 1);

                        // iterate over all possible colors in order
                        bitset_clear_all(pos_regs);
                        arch_get_allocatable_regs(pi->co->env, curr->irn, arch_pos_make_out(0), pi->co->cls, pos_regs);
                        bitset_foreach(pos_regs, col) {
                                int var_idx;
                                mangle_var(pi->buf, 'x', nnr, col);
                                var_idx = lpp_add_var(pi->curr_lp, pi->buf, binary, 0);
                                pi->last_x_var = var_idx;
                                lpp_set_factor_fast(pi->curr_lp, cst_idx, var_idx, 1);
                        }
                }
}

/**
 * Checks if all nodes in @p living are live in in block @p block.
 * @return 1 if all are live in
 *         0 else
 */
static INLINE int all_live_in(ir_node *block, pset *living) {
        ir_node *n;
        for (n = pset_first(living); n; n = pset_next(living))
                if (!is_live_in(block, n)) {
                        pset_break(living);
                        return 0;
                }
        return 1;
}

/**
 * Finds cliques in the interference graph, considering only nodes
 * for which the color pi->curr_color is possible. Finds only 'maximal-cliques',
 * viz cliques which are not conatained in another one.
 * This is used for the matrix B.
 * TODO check color
 */
static void pi_add_constr_B(ir_node *block, void *env) {
        problem_instance_t *pi = env;
        enum phase_t {growing, shrinking} phase = growing;
        struct list_head *head = get_block_border_head(pi->co->chordal_env, block);
        border_t *b;
        pset *living = pset_new_ptr(SLOTS_LIVING);

        list_for_each_entry_reverse(border_t, b, head, list) {
                const ir_node *irn = b->irn;
                if (is_removed(irn))
                        continue;

                if (b->is_def) {
                        DBG((dbg, LEVEL_2, "Def %n\n", irn));
                        pset_insert_ptr(living, irn);
                        phase = growing;
                } else { /* is_use */
                        DBG((dbg, LEVEL_2, "Use %n\n", irn));

                        /* before shrinking the set, store the current 'maximum' clique;
                         * do NOT if clique is a single node
                         * do NOT if all values are live_in (in this case they were contained in a live-out clique elsewhere) */
                        if (phase == growing && pset_count(living) >= 2 && !all_live_in(block, living)) {
                                int cst_idx;
                                ir_node *n;
                                mangle_cst(pi->buf, 'B', pi->cst_counter);
                                cst_idx = lpp_add_cst(pi->curr_lp, pi->buf, less, 1);
                                for (n = pset_first(living); n; n = pset_next(living)) {
                                        int var_idx;
                                        mangle_var_irn(pi->buf, 'x', n, pi->curr_color);
                                        var_idx = lpp_get_var_idx(pi->curr_lp, pi->buf);
                                        assert(var_idx>=1);
                                        lpp_set_factor_fast(pi->curr_lp, cst_idx, var_idx, 1);
                                }
                                pi->cst_counter++;
                        }
                        pset_remove_ptr(living, irn);
                        phase = shrinking;
                }
        }

        del_pset(living);
}

static void pi_add_constr_E(problem_instance_t *pi) {
        unit_t *curr;
        bitset_t *root_regs, *arg_regs;
        root_regs = bitset_alloca(pi->co->cls->n_regs);
        arg_regs = bitset_alloca(pi->co->cls->n_regs);

        /* for all roots of optimization units */
        list_for_each_entry(unit_t, curr, &pi->co->units, units) {
                const ir_node *root, *arg;
                int rootnr, argnr, color;
                int y_idx, i, cst_counter = 0;
                char buf[32];

                root = curr->nodes[0];
                rootnr = get_irn_graph_nr(root);
                bitset_clear_all(root_regs);
                arch_get_allocatable_regs(pi->co->env, root, arch_pos_make_out(0), pi->co->cls, root_regs);

                /* for all arguments of root */
                for (i = 1; i < curr->node_count; ++i) {
                        arg = curr->nodes[i];
                        argnr = get_irn_graph_nr(arg);
                        bitset_clear_all(arg_regs);
                        arch_get_allocatable_regs(pi->co->env, arg, arch_pos_make_out(0), pi->co->cls, arg_regs);

                        /* Introduce new variable and set factor in objective function */
                        y_idx = lpp_add_var(pi->curr_lp, NULL, real, get_weight(root, arg));

                        /* For all colors root and arg have in common, add 2 constraints to E */
                        bitset_and(arg_regs, root_regs);
                        bitset_foreach(arg_regs, color) {
                                int root_idx, arg_idx, cst_idx;
                                mangle_var(buf, 'x', rootnr, color);
                                root_idx = lpp_get_var_idx(pi->curr_lp, buf);
                                mangle_var(buf, 'x', argnr, color);
                                arg_idx = lpp_get_var_idx(pi->curr_lp, buf);

                                /* add root-arg+y <= 1 */
                                mangle_cst(buf, 'E', cst_counter++);
                                cst_idx = lpp_add_cst(pi->curr_lp, buf, less, 0);
                                lpp_set_factor_fast(pi->curr_lp, cst_idx, root_idx, 1);
                                lpp_set_factor_fast(pi->curr_lp, cst_idx, arg_idx, -1);
                                lpp_set_factor_fast(pi->curr_lp, cst_idx, y_idx, -1);

                                /* add arg-root+y <= 1 */
                                mangle_cst(buf, 'E', cst_counter++);
                                cst_idx = lpp_add_cst(pi->curr_lp, buf, less, 0);
                                lpp_set_factor_fast(pi->curr_lp, cst_idx, root_idx, -1);
                                lpp_set_factor_fast(pi->curr_lp, cst_idx, arg_idx, 1);
                                lpp_set_factor_fast(pi->curr_lp, cst_idx, y_idx, -1);
                        }
                }
        }
}

/**
 * Generate the initial problem matrices and vectors.
 */
static problem_instance_t *new_pi(const copy_opt_t *co) {

        DBG((dbg, LEVEL_1, "Generating new instance...\n"));
        problem_instance_t *pi = xcalloc(1, sizeof(*pi));
        pi->co = co;
        pi->removed = pset_new_ptr_default();
        INIT_LIST_HEAD(&pi->simplicials);
        pi->dilp = new_lpp(co->name, minimize);

        /* problem size reduction */
        pi_find_simplicials(pi);
        //TODO dump_ifg_w/o_removed

        pi->curr_lp = pi->dilp;

        /* Matrix A: knapsack constraint for each node */
        dom_tree_walk_irg(co->irg, pi_add_constr_A, NULL, pi);
        /* Matrix B: interference constraints using cliques */
        for (pi->curr_color = 0; pi->curr_color < pi->co->cls->n_regs; ++pi->curr_color)
                dom_tree_walk_irg(co->irg, pi_add_constr_B, NULL, pi);
        /* Matrix E weights for the 'same-color-optimization' target */
        pi_add_constr_E(pi);
        return pi;
}

/**
 * Clean the problem instance
 */
static void free_pi(problem_instance_t *pi) {
        DBG((dbg, LEVEL_1, "Free instance...\n"));
        /* pi->simplicials get freed during apply_solution */
        free_lpp(pi->dilp);
        del_pset(pi->removed);
        free(pi);
}

/**
 * Set starting values for the mip problem according
 * to the current coloring of the graph.
 */
static void pi_set_start_sol(problem_instance_t *pi) {
        int i;
        for (i=1; i<=pi->last_x_var; ++i) {
                int nnr, col;
                double val;
                /* get varibale name */
                const char *var_name = lpp_get_var_name(pi->curr_lp, i);
                /* split into components */
                if (split_var(var_name, &nnr, &col) == 2) {
                        assert(get_irn_col(pi->co, get_irn_for_graph_nr(pi->co->irg, nnr)) != -1);
                        val = (get_irn_col(pi->co, get_irn_for_graph_nr(pi->co->irg, nnr)) == col) ? 1 : 0;
                        lpp_set_start_value(pi->curr_lp, i, val);
                } else
                        assert(0 && "x vars always look like this \"x123_45\"");
        }
}

/**
 * Invoke a solver
 */
static void pi_solve_ilp(problem_instance_t *pi) {
        pi_set_start_sol(pi);
        lpp_solve(pi->curr_lp, 1);
}

/**
 * Set the color of all simplicial nodes removed form
 * the graph before transforming it to an ilp.
 */
static void pi_set_simplicials(problem_instance_t *pi) {
        simpl_t *simpl, *tmp;
        bitset_t *used_cols = bitset_alloca(arch_register_class_n_regs(pi->co->cls));

        /* color the simplicial nodes in right order */
        list_for_each_entry_safe(simpl_t, simpl, tmp, &pi->simplicials, chain) {
                int free_col;
                ir_node *other_irn, *irn;
                if_node_t *other, *ifn;

                /* get free color by inspecting all neighbors */
                ifn = simpl->ifn;
                irn = get_irn_for_graph_nr(pi->co->irg, ifn->nnr);
                bitset_clear_all(used_cols);
                foreach_neighb(ifn, other) {
                        other_irn = get_irn_for_graph_nr(pi->co->irg, other->nnr);
                        if (!is_removed(other_irn)) /* only inspect nodes which are in graph right now */
                                bitset_set(used_cols, get_irn_col(pi->co, other_irn));
                }

                /* now all bits not set are possible colors */
                free_col = bitset_next_clear(used_cols, 0);
                assert(free_col != -1 && "No free color found. This can not be.");
                set_irn_col(pi->co, irn, free_col);
                pset_remove_ptr(pi->removed, irn); /* irn is back in graph again */
                free(simpl);
        }
}

/**
 * Sets the colors of irns according to the values of variables
 * provided by the solution of the solver.
 */
static void pi_apply_solution(problem_instance_t *pi) {
//              else if (vars_section && sscanf(buf, "x%d_%d %d", &num, &col, &val) == 3 && val == 1) {
//                      set_irn_col(lpp, get_irn_for_graph_nr(lpp->irg, num), col);
        int i;
        double *sol;
        DBG((dbg, LEVEL_1, "Applying solution...\n"));

#ifdef DO_STAT
        //TODO
#endif

        sol = xmalloc(pi->last_x_var * sizeof(*sol));
        lpp_get_solution(pi->curr_lp, sol, 1, pi->last_x_var);
        for (i=0; i<pi->last_x_var; ++i)
                if (sol[i] == 1) { /* split varibale name into components */
                        int nnr, col;
                        const char *var_name = lpp_get_var_name(pi->curr_lp, 1+i);
                        if (split_var(var_name, &nnr, &col) == 2) {
                                DBG((dbg, LEVEL_2, " x%d = %d\n", nnr, col));
                                set_irn_col(pi->co, get_irn_for_graph_nr(pi->co->irg, nnr), col);
                        } else
                                assert(0 && "this should be a x-var");
        }
        pi_set_simplicials(pi);
}

void co_ilp_opt(copy_opt_t *co) {
        problem_instance_t *pi;
        dbg = firm_dbg_register("ir.be.copyoptilp");
        if (!strcmp(co->name, DEBUG_IRG))
                firm_dbg_set_mask(dbg, -1);
        else
                firm_dbg_set_mask(dbg, DEBUG_LVL);

        pi = new_pi(co);
        pi_solve_ilp(pi);
        pi_apply_solution(pi);
        free_pi(pi);
}