[libfirm] / ir / be / bechordal.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
 * @brief       Chordal register allocation.
 * @author      Sebastian Hack
 * @date        08.12.2004
 */
#include "config.h"

#include <ctype.h>

#include "obst.h"
#include "pset.h"
#include "list.h"
#include "bitset.h"
#include "raw_bitset.h"
#include "bipartite.h"
#include "hungarian.h"

#include "irmode_t.h"
#include "irgraph_t.h"
#include "irprintf_t.h"
#include "irgwalk.h"
#include "irdump.h"
#include "irdom.h"
#include "irtools.h"
#include "debug.h"
#include "iredges.h"

#include "beutil.h"
#include "besched.h"
#include "besched.h"
#include "belive_t.h"
#include "benode.h"
#include "bearch.h"
#include "beirgmod.h"
#include "beifg.h"
#include "beinsn_t.h"
#include "statev_t.h"
#include "beirg.h"
#include "beintlive_t.h"
#include "bera.h"
#include "bechordal_t.h"
#include "bechordal_draw.h"
#include "bemodule.h"
#include "bearch.h"
#include "bechordal_common.h"

DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)

typedef struct be_chordal_alloc_env_t {
        be_chordal_env_t *chordal_env;

        pset *pre_colored;     /**< Set of precolored nodes. */
        bitset_t *live;        /**< A liveness bitset. */
        bitset_t *tmp_colors;  /**< An auxiliary bitset which is as long as the number of colors in the class. */
        bitset_t *colors;      /**< The color mask. */
        bitset_t *in_colors;   /**< Colors used by live in values. */
        int colors_n;          /**< The number of colors. */
} be_chordal_alloc_env_t;

static int get_next_free_reg(const be_chordal_alloc_env_t *alloc_env, bitset_t *colors)
{
        bitset_t *tmp = alloc_env->tmp_colors;
        bitset_copy(tmp, colors);
        bitset_flip_all(tmp);
        bitset_and(tmp, alloc_env->chordal_env->allocatable_regs);
        return bitset_next_set(tmp, 0);
}

static bitset_t const *get_decisive_partner_regs(be_operand_t const *const o1)
{
        be_operand_t const *const o2 = o1->partner;
        assert(!o2 || o1->req->cls == o2->req->cls);

        if (!o2 || bitset_contains(o1->regs, o2->regs)) {
                return o1->regs;
        } else if (bitset_contains(o2->regs, o1->regs)) {
                return o2->regs;
        } else {
                return NULL;
        }
}

static void pair_up_operands(const be_chordal_alloc_env_t *alloc_env, be_insn_t *insn)
{
        const be_chordal_env_t *env = alloc_env->chordal_env;
        bitset_t               *bs  = bitset_alloca(env->cls->n_regs);
        int                     i;
        int                     j;

        /*
         * For each out operand, try to find an in operand which can be assigned the
         * same register as the out operand.
         */
        for (j = 0; j < insn->use_start; ++j) {
                be_operand_t *smallest        = NULL;
                int           smallest_n_regs = env->cls->n_regs + 1;
                be_operand_t *out_op          = &insn->ops[j];

                /* Try to find an in operand which has ... */
                for (i = insn->use_start; i < insn->n_ops; ++i) {
                        int           n_total;
                        be_operand_t *op = &insn->ops[i];
                        be_lv_t      *lv;

                        if (op->partner != NULL)
                                continue;
                        lv = be_get_irg_liveness(env->irg);
                        if (be_values_interfere(lv, op->irn, op->carrier))
                                continue;

                        bitset_copy(bs, op->regs);
                        bitset_and(bs, out_op->regs);
                        n_total = bitset_popcount(op->regs);

                        if (!bitset_is_empty(bs) && n_total < smallest_n_regs) {
                                smallest        = op;
                                smallest_n_regs = n_total;
                        }
                }

                if (smallest != NULL) {
                        for (i = insn->use_start; i < insn->n_ops; ++i) {
                                if (insn->ops[i].carrier == smallest->carrier)
                                        insn->ops[i].partner = out_op;
                        }

                        out_op->partner   = smallest;
                        smallest->partner = out_op;
                }
        }
}

static void handle_constraints(be_chordal_alloc_env_t *alloc_env,
                                   ir_node *irn)
{
        int n_regs;
        ir_node **alloc_nodes;
        //hungarian_problem_t *bp;
        int *assignment;
        pmap *partners;
        int i, n_alloc;
        ir_node *perm = NULL;
        //int match_res, cost;
        be_chordal_env_t *env  = alloc_env->chordal_env;
        void *base             = obstack_base(env->obst);
        be_insn_t *insn        = be_scan_insn(env, irn);
        bipartite_t *bp;

        if (insn->pre_colored) {
                int i;
                for (i = 0; i < insn->use_start; ++i)
                        pset_insert_ptr(alloc_env->pre_colored, insn->ops[i].carrier);
        }

        /*
         * Perms inserted before the constraint handling phase are considered to be
         * correctly precolored. These Perms arise during the ABI handling phase.
         */
        if (!insn->has_constraints || is_Phi(irn))
                goto end;

        n_regs      = env->cls->n_regs;
        alloc_nodes = ALLOCAN(ir_node*, n_regs);
        //bp          = hungarian_new(n_regs, n_regs, 2, HUNGARIAN_MATCH_PERFECT);
        bp          = bipartite_new(n_regs, n_regs);
        assignment  = ALLOCAN(int, n_regs);
        partners    = pmap_create();

        /*
         * prepare the constraint handling of this node.
         * Perms are constructed and Copies are created for constrained values
         * interfering with the instruction.
         */
        perm = pre_process_constraints(alloc_env->chordal_env, &insn);

        /* find suitable in operands to the out operands of the node. */
        pair_up_operands(alloc_env, insn);

        /*
         * look at the in/out operands and add each operand (and its possible partner)
         * to a bipartite graph (left: nodes with partners, right: admissible colors).
         */
        for (i = 0, n_alloc = 0; i < insn->n_ops; ++i) {
                be_operand_t *op = &insn->ops[i];

                /*
                 * If the operand has no partner or the partner has not been marked
                 * for allocation, determine the admissible registers and mark it
                 * for allocation by associating the node and its partner with the
                 * set of admissible registers via a bipartite graph.
                 */
                if (!op->partner || !pmap_contains(partners, op->partner->carrier)) {
                        ir_node *partner = op->partner ? op->partner->carrier : NULL;
                        int i;

                        pmap_insert(partners, op->carrier, partner);
                        if (partner != NULL)
                                pmap_insert(partners, partner, op->carrier);

                        /* don't insert a node twice */
                        for (i = 0; i < n_alloc; ++i) {
                                if (alloc_nodes[i] == op->carrier) {
                                        break;
                                }
                        }
                        if (i < n_alloc)
                                continue;

                        alloc_nodes[n_alloc] = op->carrier;

                        DBG((dbg, LEVEL_2, "\tassociating %+F and %+F\n", op->carrier,
                             partner));

                        bitset_t const *const bs = get_decisive_partner_regs(op);
                        if (bs) {
                                DBG((dbg, LEVEL_2, "\tallowed registers for %+F: %B\n", op->carrier, bs));

                                bitset_foreach(bs, col) {
                                        //hungarian_add(bp, n_alloc, col, 1);
                                        bipartite_add(bp, n_alloc, col);
                                }
                        } else {
                                DBG((dbg, LEVEL_2, "\tallowed registers for %+F: none\n", op->carrier));
                        }

                        n_alloc++;
                }
        }

        /*
         * Put all nodes which live through the constrained instruction also to the
         * allocation bipartite graph. They are considered unconstrained.
         */
        if (perm != NULL) {
                foreach_out_edge(perm, edge) {
                        int i;
                        ir_node *proj = get_edge_src_irn(edge);
                        be_lv_t *lv   = be_get_irg_liveness(env->irg);

                        assert(is_Proj(proj));

                        if (!be_values_interfere(lv, proj, irn)
                            || pmap_contains(partners, proj))
                                continue;

                        /* don't insert a node twice */
                        for (i = 0; i < n_alloc; ++i) {
                                if (alloc_nodes[i] == proj) {
                                        break;
                                }
                        }
                        if (i < n_alloc)
                                continue;


                        assert(n_alloc < n_regs);

                        alloc_nodes[n_alloc] = proj;
                        pmap_insert(partners, proj, NULL);

                        bitset_foreach(env->allocatable_regs, col) {
                                //hungarian_add(bp, n_alloc, col, 1);
                                bipartite_add(bp, n_alloc, col);
                        }

                        n_alloc++;
                }
        }

        /* Compute a valid register allocation. */
#if 0
        hungarian_prepare_cost_matrix(bp, HUNGARIAN_MODE_MAXIMIZE_UTIL);
        match_res = hungarian_solve(bp, assignment, &cost, 1);
        assert(match_res == 0 && "matching failed");
#else
        /*bipartite_dump_f(stderr, bp);*/
        bipartite_matching(bp, assignment);
#endif

        /* Assign colors obtained from the matching. */
        for (i = 0; i < n_alloc; ++i) {
                const arch_register_t *reg;
                ir_node *irn;

                assert(assignment[i] >= 0 && "there must have been a register assigned (node not register pressure faithful?)");
                reg = arch_register_for_index(env->cls, assignment[i]);

                irn = alloc_nodes[i];
                if (irn != NULL) {
                        arch_set_irn_register(irn, reg);
                        (void) pset_hinsert_ptr(alloc_env->pre_colored, irn);
                        DBG((dbg, LEVEL_2, "\tsetting %+F to register %s\n", irn, reg->name));
                }

                irn = pmap_get(ir_node, partners, alloc_nodes[i]);
                if (irn != NULL) {
                        arch_set_irn_register(irn, reg);
                        (void) pset_hinsert_ptr(alloc_env->pre_colored, irn);
                        DBG((dbg, LEVEL_2, "\tsetting %+F to register %s\n", irn, reg->name));
                }
        }

        /* Allocate the non-constrained Projs of the Perm. */
        if (perm != NULL) {
                /* Put the colors of all Projs in a bitset. */
                bitset_t *const bs = bitset_alloca(n_regs);
                foreach_out_edge(perm, edge) {
                        ir_node *proj              = get_edge_src_irn(edge);
                        const arch_register_t *reg = arch_get_irn_register(proj);

                        if (reg != NULL)
                                bitset_set(bs, reg->index);
                }

                /* Assign the not yet assigned Projs of the Perm a suitable color. */
                foreach_out_edge(perm, edge) {
                        ir_node *proj              = get_edge_src_irn(edge);
                        const arch_register_t *reg = arch_get_irn_register(proj);

                        DBG((dbg, LEVEL_2, "\tchecking reg of %+F: %s\n", proj, reg ? reg->name : "<none>"));

                        if (reg == NULL) {
                                size_t const col = get_next_free_reg(alloc_env, bs);
                                reg = arch_register_for_index(env->cls, col);
                                bitset_set(bs, reg->index);
                                arch_set_irn_register(proj, reg);
                                pset_insert_ptr(alloc_env->pre_colored, proj);
                                DBG((dbg, LEVEL_2, "\tsetting %+F to register %s\n", proj, reg->name));
                        }
                }
        }

        bipartite_free(bp);
        //hungarian_free(bp);
        pmap_destroy(partners);

end:
        obstack_free(env->obst, base);
}

/**
 * Handle constraint nodes in each basic block.
 * handle_constraints() inserts Perm nodes which perm
 * over all values live at the constrained node right in front
 * of the constrained node. These Perms signal a constrained node.
 * For further comments, refer to handle_constraints().
 */
static void constraints(ir_node *bl, void *data)
{
        be_chordal_alloc_env_t *env    = (be_chordal_alloc_env_t*)data;
        ir_node                *irn;

        for (irn = sched_first(bl); !sched_is_end(irn);) {
                ir_node *const next = sched_next(irn);
                handle_constraints(env, irn);
                irn = next;
        }
}

static void assign(ir_node *block, void *env_ptr)
{
        be_chordal_alloc_env_t *alloc_env = (be_chordal_alloc_env_t*)env_ptr;
        be_chordal_env_t *env       = alloc_env->chordal_env;
        bitset_t *live              = alloc_env->live;
        bitset_t *colors            = alloc_env->colors;
        bitset_t *in_colors         = alloc_env->in_colors;
        struct list_head *head      = get_block_border_head(env, block);
        be_lv_t *lv                 = be_get_irg_liveness(env->irg);

        bitset_clear_all(colors);
        bitset_clear_all(live);
        bitset_clear_all(in_colors);

        DBG((dbg, LEVEL_4, "Assigning colors for block %+F\n", block));
        DBG((dbg, LEVEL_4, "\tusedef chain for block\n"));
        foreach_border_head(head, b) {
                DBG((dbg, LEVEL_4, "\t%s %+F/%d\n", b->is_def ? "def" : "use",
                                        b->irn, get_irn_idx(b->irn)));
        }

        /*
         * Add initial defs for all values live in.
         * Since their colors have already been assigned (The dominators were
         * allocated before), we have to mark their colors as used also.
         */
        be_lv_foreach(lv, block, be_lv_state_in, irn) {
                if (has_reg_class(env, irn)) {
                        const arch_register_t *reg = arch_get_irn_register(irn);

                        assert(reg && "Node must have been assigned a register");
                        DBG((dbg, LEVEL_4, "%+F has reg %s\n", irn, reg->name));

                        /* Mark the color of the live in value as used. */
                        int const col = reg->index;
                        bitset_set(colors, col);
                        bitset_set(in_colors, col);

                        /* Mark the value live in. */
                        bitset_set(live, get_irn_idx(irn));
                }
        }

        /*
         * Mind that the sequence of defs from back to front defines a perfect
         * elimination order. So, coloring the definitions from first to last
         * will work.
         */
        foreach_border_head(head, b) {
                ir_node *irn = b->irn;
                int nr       = get_irn_idx(irn);
                int ignore   = arch_irn_is_ignore(irn);

                /*
                 * Assign a color, if it is a local def. Global defs already have a
                 * color.
                 */
                if (b->is_def && !be_is_live_in(lv, block, irn)) {
                        const arch_register_t *reg;
                        int col;

                        if (ignore || pset_find_ptr(alloc_env->pre_colored, irn)) {
                                reg = arch_get_irn_register(irn);
                                col = reg->index;
                                assert(!bitset_is_set(colors, col) && "pre-colored register must be free");
                        } else {
                                col = get_next_free_reg(alloc_env, colors);
                                reg = arch_register_for_index(env->cls, col);
                                assert(arch_get_irn_register(irn) == NULL && "This node must not have been assigned a register yet");
                        }

                        bitset_set(colors, col);
                        arch_set_irn_register(irn, reg);

                        DBG((dbg, LEVEL_1, "\tassigning register %s(%d) to %+F\n", reg->name, col, irn));

                        assert(!bitset_is_set(live, nr) && "Value's definition must not have been encountered");
                        bitset_set(live, nr);
                } else if (!b->is_def) {
                        /* Clear the color upon a use. */
                        const arch_register_t *reg = arch_get_irn_register(irn);

                        assert(reg && "Register must have been assigned");

                        bitset_clear(colors, reg->index);
                        bitset_clear(live, nr);
                }
        }
}

static void be_ra_chordal_color(be_chordal_env_t *const chordal_env)
{
        be_chordal_alloc_env_t env;
        char buf[256];
        const arch_register_class_t *cls = chordal_env->cls;

        int       colors_n = arch_register_class_n_regs(cls);
        ir_graph *irg      = chordal_env->irg;

        be_assure_live_sets(irg);
        assure_doms(irg);

        env.chordal_env   = chordal_env;
        env.colors_n      = colors_n;
        env.colors        = bitset_alloca(colors_n);
        env.tmp_colors    = bitset_alloca(colors_n);
        env.in_colors     = bitset_alloca(colors_n);
        env.pre_colored   = pset_new_ptr_default();

        be_timer_push(T_SPLIT);

        if (chordal_env->opts->dump_flags & BE_CH_DUMP_SPLIT) {
                snprintf(buf, sizeof(buf), "%s-split", chordal_env->cls->name);
                dump_ir_graph(chordal_env->irg, buf);
        }

        be_timer_pop(T_SPLIT);

        be_timer_push(T_CONSTR);

        /* Handle register targeting constraints */
        dom_tree_walk_irg(irg, constraints, NULL, &env);

        if (chordal_env->opts->dump_flags & BE_CH_DUMP_CONSTR) {
                snprintf(buf, sizeof(buf), "%s-constr", chordal_env->cls->name);
                dump_ir_graph(chordal_env->irg, buf);
        }

        be_timer_pop(T_CONSTR);

        env.live = bitset_malloc(get_irg_last_idx(chordal_env->irg));

        /* First, determine the pressure */
        dom_tree_walk_irg(irg, create_borders, NULL, env.chordal_env);

        /* Assign the colors */
        dom_tree_walk_irg(irg, assign, NULL, &env);

        if (chordal_env->opts->dump_flags & BE_CH_DUMP_TREE_INTV) {
                plotter_t *plotter;
                ir_snprintf(buf, sizeof(buf), "ifg_%s_%F.eps", chordal_env->cls->name, irg);
                plotter = new_plotter_ps(buf);
                draw_interval_tree(&draw_chordal_def_opts, chordal_env, plotter);
                plotter_free(plotter);
        }

        bitset_free(env.live);
        del_pset(env.pre_colored);
}

BE_REGISTER_MODULE_CONSTRUCTOR(be_init_chordal)
void be_init_chordal(void)
{
        static be_ra_chordal_coloring_t coloring = {
                be_ra_chordal_color
        };
        FIRM_DBG_REGISTER(dbg, "firm.be.chordal");

        be_register_chordal_coloring("default", &coloring);
}