[libfirm] / ir / be / bechordal.c

/**
 * Chordal register allocation.
 * @author Sebastian Hack
 * @date 8.12.2004
 */

#include <ctype.h>

#include "obst.h"
#include "list.h"
#include "bitset.h"
#include "iterator.h"

#include "irmode_t.h"
#include "irprintf_t.h"
#include "irgwalk.h"
#include "irgraph.h"
#include "irdump.h"
#include "irdom.h"
#include "xmalloc.h"

#include "beutil.h"
#include "besched.h"
#include "bera_t.h"
#include "benumb_t.h"
#include "besched_t.h"
#include "belive_t.h"

#define TEST_COLORS 2048

/** An interval border. */
typedef struct _border_t {
        struct list_head list;          /**< list head for queuing. */
        const ir_node *irn;                             /**< The node. */
        unsigned step;                                          /**< The number equal to the interval border. */
        unsigned is_def : 1;                    /**< Does this border denote a use or a def. */
} border_t;

typedef struct _if_edge_t {
        int src, tgt;
} if_edge_t;

#define IF_EDGE_HASH(e) ((e)->src)

static int if_edge_cmp(const void *p1, const void *p2, size_t size)
{
        const if_edge_t *e1 = p1;
        const if_edge_t *e2 = p2;

        return !(e1->src == e2->src && e1->tgt == e2->tgt);
}

typedef struct _env_t {
        struct obstack obst;    /**< An obstack for temporary storage. */
        set *phi_if;                                    /**< The phi interference map. */
        bitset_t *live;                 /**< A live bitset to use in every block. */
        bitset_t *processed;    /**< A set marking processed blocks. */
        bitset_t *colors;                       /**< The color mask. */
} env_t;

typedef struct _be_chordal_dump_params_t {
        int x_dist;
        int y_dist;
        double font_scale;
} be_chordal_dump_params_t;

static const be_chordal_dump_params_t dump_params = {
        30,
        10,
        4
};

static void draw_interval_graphs(ir_node *block,
                struct list_head *border_head,
                const be_chordal_dump_params_t *params)
{
        int i;
        int x_dist = params->x_dist;
        int y_dist = params->y_dist;
        ir_graph *irg = get_irn_irg(block);

        FILE *f;
        char buf[1024];

        ir_snprintf(buf, sizeof(buf), "%s_bl%N.eps",
                        get_entity_name(get_irg_entity(irg)), block);

        if((f = fopen(buf, "wt")) != NULL) {
                border_t *b;
                int *seen = xcalloc(get_graph_node_count(irg), sizeof(seen[0]));
                int last_pos = list_empty(border_head) ? 0 : list_entry(border_head->prev, border_t, list)->step;
                int max_col = 0;

                list_for_each_entry_reverse(border_t, b, border_head, list) {
                        const ir_node *irn = b->irn;
                        int col = get_irn_color(irn);
                        max_col = max_col > col ? max_col : col;
                }

                fprintf(f, "%%!PS-Adobe-2.0\n");
                fprintf(f, "%%%%BoundingBox: -10 -10 %d %d\n",
                                x_dist * last_pos + x_dist, y_dist * max_col + y_dist);
                fprintf(f, "/mainfont /Courier findfont %f scalefont def\n", params->font_scale);
                fprintf(f, "mainfont setfont\n");
                fprintf(f, "0.2 setlinewidth\n");

                for(i = 0; i <= last_pos; ++i) {
                        fprintf(f, "0 0 0 setrgbcolor\n");
                        fprintf(f, "%d %d moveto\n", i * x_dist, -2);
                        fprintf(f, "%d %d lineto\n", i * x_dist, max_col * y_dist + 2);
                        fprintf(f, "stroke\n");
                }
                fprintf(f, "0.5 setlinewidth\n");

                list_for_each_entry_reverse(border_t, b, border_head, list) {
                        const ir_node *irn = b->irn;
                        int nr = get_irn_graph_nr(irn);

                        if(b->is_def)
                                seen[nr] = b->step;
                        else {
                                int col = get_irn_color(irn);

                                int pos = last_pos - seen[nr];
                                int end_pos = last_pos - b->step;
                                int live_in = is_live_in(block, irn);
                                int live_out = is_live_out(block, irn);
                                int y_val = y_dist * col;

                                int red = 0;
                                int green = live_out;
                                int blue = live_in;

                                fprintf(f, "0 0 0 setrgbcolor\n");
                                fprintf(f, "%d %d moveto\n", x_dist * pos + 2, y_val + 2);
                                ir_fprintf(f, "(%n/%d%s) show\n", irn, nr, is_phi_operand(irn) ? "*" : "");
                                fprintf(f, "%d %d %d setrgbcolor\n", red, green, blue);
                                fprintf(f, "%d %d moveto\n", x_dist * pos, y_val);
                                fprintf(f, "%d %d lineto\n", (x_dist * end_pos) - 5, y_val);
                                fprintf(f, "stroke\n");
                        }
                }

                free(seen);
                fclose(f);
        }
}

static INLINE if_edge_t *edge_init(if_edge_t *edge, int src, int tgt)
{
        /* Bring the smaller entry to src. */
        if(src > tgt) {
                edge->src = tgt;
                edge->tgt = src;
        } else {
                edge->src = src;
                edge->tgt = tgt;
        }

        return edge;
}

static INLINE void add_if(const env_t *env, int src, int tgt)
{
        if_edge_t edge;
        edge_init(&edge, src, tgt);
        set_insert(env->phi_if, &edge, sizeof(edge), IF_EDGE_HASH(&edge));
}

static INLINE int are_connected(const env_t *env, int src, int tgt)
{
        if_edge_t edge;
        edge_init(&edge, src, tgt);
        return set_find(env->phi_if, &edge, sizeof(edge), IF_EDGE_HASH(&edge)) != NULL;
}



static INLINE border_t *border_add(env_t *env, struct list_head *head,
                        const ir_node *irn, int step, int is_def)
{
        border_t *b = obstack_alloc(&env->obst, sizeof(*b));
        b->is_def = is_def;
        b->irn = irn;
        b->step = step;
        list_add_tail(&b->list, head);
        return b;
}

static void block_alloc(ir_node *block, void *env_ptr)
{
        env_t *env = env_ptr;
        struct obstack *obst = &env->obst;
        void *obstack_level = obstack_base(obst);
        bitset_t *live = env->live;
        bitset_t *colors = env->colors;
        ir_graph *irg = get_irn_irg(block);

        int i, n;
        unsigned step = 0;
        int block_nr = get_block_graph_nr(block);
        const ir_node *irn;
        border_t *b;
        struct list_head head;
        pset *live_in = get_live_in(block);
        pset *live_out = get_live_out(block);
        ir_node *idom = get_Block_idom(block);

        /*
         * Check, if this block has already been processed, if true, return
         * immediately.
         */
        if(bitset_is_set(env->processed, block_nr))
                return;

        /*
         * Ensure, that the immediate dominator of this block is allocated
         * before this block, since the values live in at this block are
         * defined in the dominators of this block. Coloring the dominators
         * thus is vital before coloring this block.
         */
        if(idom)
                block_alloc(idom, env);

        /* Clear the live and allocate the color bitset. */
        bitset_clear_all(live);
        bitset_clear_all(colors);

        INIT_LIST_HEAD(&head);

        /*
         * Make final uses of all values live out of the block.
         * They are neccessary to build up real intervals.
         */
        for(irn = pset_first(live_out); irn; irn = pset_next(live_out)) {
                bitset_set(live, get_irn_graph_nr(irn));
                if(!is_Phi(irn) && is_allocatable_irn(irn))
                        border_add(env, &head, irn, step, 0);
        }

        ++step;

        /*
         * Determine the last uses of a value inside the block, since they are
         * relevant for the interval borders.
         */
        sched_foreach_reverse(block, irn) {
                ir_debugf("insn: %n\n", irn);
                ir_debugf("live: %b\n", live);

                get_irn_ra_info(irn)->color = NO_COLOR;

                /*
                 * If the node defines a datab value, i.e. something, registers must
                 * be allocated for, add a new def border to the border list.
                 */
                if(is_allocatable_irn(irn)) {
                        unsigned long elm;
                        int nr = get_irn_graph_nr(irn);

                        bitset_clear(live, nr);
                        border_add(env, &head, irn, step, 1);

                        if(is_phi_operand(irn)) {
                                bitset_foreach(live, elm) {
                                        int live_nr = (int) elm;
                                        ir_node *live_irn = get_irn_for_graph_nr(irg, live_nr);
                                        if(is_phi_operand(live_irn)) {
                                                ir_debugf("\t\tinterfering phi operands: %n, %n\n", irn, live_irn);
                                                add_if(env, nr, live_nr);
                                        }
                                }
                        }
                }

                /*
                 * If the node is no phi node we can examine the uses.
                 */
                if(!is_Phi(irn)) {
                        for(i = 0, n = get_irn_arity(irn); i < n; ++i) {
                                ir_node *op = get_irn_n(irn, i);

                                if(is_allocatable_irn(op)) {
                                        int nr = get_irn_graph_nr(op);

                                        ir_debugf("\t\tpos: %d, use: %n\n", i, op);

                                        if(!bitset_is_set(live, nr)) {
                                                border_add(env, &head, op, step, 0);
                                                bitset_set(live, nr);
                                        }
                                }
                        }
                }

                ++step;
        }

        bitset_clear_all(live);

        /*
         * 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.
         */
        for(irn = pset_first(live_in); irn; irn = pset_next(live_in)) {
                if(is_allocatable_irn(irn)) {
                        int col = get_irn_color(irn);

                        /* Mark the color of the live in value as used. */
                        assert(is_color(col) && "Node must have been assigned a color.");
                        bitset_set(colors, col);

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

                        /* Add the def */
                        border_add(env, &head, irn, step, 1);
                }
        }

        ir_debugf("usedef chain for block %n\n", block);
        list_for_each_entry(border_t, b, &head, list) {
                ir_debugf("\t%s %n %d\n", b->is_def ? "def" : "use", b->irn, get_irn_graph_nr(b->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.
         */
        list_for_each_entry_reverse(border_t, b, &head, list) {
                const ir_node *irn = b->irn;
                int nr = get_irn_graph_nr(irn);

                /*
                 * Assign a color, if it is a local def. Global defs already have a
                 * color.
                 */
                if(b->is_def && !is_live_in(block, irn)) {
                        ra_info_t *ri = get_irn_ra_info(irn);
                        int col = bitset_next_clear(colors, 0);

                        assert(!is_color(get_irn_color(irn)) && "Color must not have assigned");
                        assert(!bitset_is_set(live, nr) && "Value def must not have been encountered");

                        bitset_set(colors, col);
                        bitset_set(live, nr);

                        ri->color = col;
                        ri->pressure = bitset_popcnt(colors);

                        ir_debugf("\tassigning color %d to %n\n", col, irn);
                }

                /* Clear the color upon a use. */
                else if(!b->is_def) {
                        int col = get_irn_ra_info(irn)->color;

                        assert(bitset_is_set(live, nr) && "Cannot have a non live use");
                        assert(is_color(col) && "A color must have been assigned");

                        bitset_clear(colors, col);
                        bitset_clear(live, nr);
                }
        }

        draw_interval_graphs(block, &head, &dump_params);

        /* Mark this block has processed. */
        bitset_set(env->processed, block_nr);

        /* Reset the obstack to its initial level */
        obstack_free(obst, obstack_level);
}


void be_ra_chordal(ir_graph *irg)
{
        int node_count = get_graph_node_count(irg);
        env_t *env = malloc(sizeof(*env));

        if(get_irg_dom_state(irg) != dom_consistent)
                compute_doms(irg);

        obstack_init(&env->obst);
        env->phi_if = new_set(if_edge_cmp, node_count);
        env->live = bitset_obstack_alloc(&env->obst, node_count);
        env->processed = bitset_obstack_alloc(&env->obst, get_graph_block_count(irg));
        env->colors = bitset_obstack_alloc(&env->obst, TEST_COLORS);

        irg_block_walk_graph(irg, block_alloc, NULL, env);
        obstack_free(&env->obst, NULL);

        set_irg_ra_link(irg, env);
}

void be_ra_chordal_done(ir_graph *irg)
{
        env_t *env = get_irg_ra_link(irg);
        free(env->phi_if);
        free(env);
}

int phi_ops_interfere(const ir_node *a, const ir_node *b)
{
        ir_graph *irg = get_irn_irg(a);
        env_t *env = get_irg_ra_link(irg);

        assert(irg == get_irn_irg(b) && "Both nodes must be in the same graph");

        return are_connected(env, get_irn_graph_nr(a), get_irn_graph_nr(b));
}