[libfirm] / ir / be / bechordal.c

/**
 * Chordal register allocation.
 * @author Sebastian Hack
 * @date 8.12.2004
 *
 * Copyright (C) Universitaet Karlsruhe
 * Released under the GPL
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <ctype.h>

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

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

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

#include "bechordal_t.h"
#include "bechordal_draw.h"

#define DBG_LEVEL 0 //SET_LEVEL_4
#define NO_COLOR (-1)

#undef DUMP_INTERVALS
#undef DUMP_PRESSURE
#undef DUMP_IFG

#if defined(DUMP_IFG) && !defined(BUILD_GRAPH)
#error Must define BUILD_GRAPH to be able to dump it.
#endif


#include "fourcc.h"

/* Make a fourcc for border checking. */
#define BORDER_FOURCC                           FOURCC('B', 'O', 'R', 'D')

static firm_dbg_module_t *dbg;

#ifdef BUILD_GRAPH

#define IF_EDGE_HASH(e) ((e)->src)
#define IF_NODE_HASH(n) ((n)->nnr)

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);
}

static int if_node_cmp(const void *p1, const void *p2, size_t size)
{
        const if_node_t *n1 = p1;
        const if_node_t *n2 = p2;

        return n1->nnr != n2->nnr;
}

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 be_chordal_env_t *env, int src, int tgt)
{
        if_edge_t edge;
        if_node_t node, *src_node, *tgt_node;
        /* insert edge */
        edge_init(&edge, src, tgt);
        set_insert(env->edges, &edge, sizeof(edge), IF_EDGE_HASH(&edge));

        /* insert nodes */
        node.nnr = src;
        node.neighb = pset_new_ptr(8);
        src_node = set_insert(env->nodes, &node, sizeof(node), IF_NODE_HASH(&node));
        node.nnr = tgt;
        node.neighb = pset_new_ptr(8);
        tgt_node = set_insert(env->nodes, &node, sizeof(node), IF_NODE_HASH(&node));

        /* insert neighbors into nodes */
        pset_insert_ptr(src_node->neighb, tgt_node);
        pset_insert_ptr(tgt_node->neighb, src_node);
}

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

int ifg_has_edge(const be_chordal_env_t *env, const if_node_t *n1, const if_node_t* n2) {
        return are_connected(env, n1->nnr, n2->nnr);
}

#ifdef DUMP_IFG

static void dump_ifg(const be_chordal_env_t *env)
{
        FILE *f;
        set *edges = env->edges;
        ir_graph *irg = env->irg;
        char filename[128];

        ir_snprintf(filename, sizeof(filename), "ifg_%s_%F.dot", env->cls->name, irg);

        if((f = fopen(filename, "wt")) != NULL) {
                bitset_pos_t pos;
                int n_edges = 0;
                if_edge_t *edge;
                bitset_t *bs = bitset_malloc(get_graph_node_count(irg));

                ir_fprintf(f, "graph \"%F\" {\n", irg);
                fprintf(f, "\tnode [shape=box,style=filled]\n");

                for(edge = set_first(edges); edge; edge = set_next(edges)) {
                        bitset_set(bs, edge->src);
                        bitset_set(bs, edge->tgt);
                        n_edges++;
                }

                fprintf(f, "\tx [label=\"nodes: %u, edges: %d\"]\n", bitset_popcnt(bs), n_edges);

                bitset_foreach(bs, pos) {
                        int nr = (int) pos;
                        ir_node *irn = get_irn_for_graph_nr(irg, nr);

                        ir_fprintf(f, "\tn%d [label=\"%+F\"]\n", nr, irn);
                }

                for(edge = set_first(edges); edge; edge = set_next(edges)) {
                        fprintf(f, "\tn%d -- n%d [len=5]\n", edge->src, edge->tgt);
                }

                fprintf(f, "}\n");
                fclose(f);

                bitset_free(bs);
        }

}

#endif /* DUMP_IFG */

#endif /* BUILD_GRAPH */

static void check_border_list(struct list_head *head)
{
  border_t *x;
  list_for_each_entry(border_t, x, head, list) {
    assert(x->magic == BORDER_FOURCC);
  }
}

static void check_heads(be_chordal_env_t *env)
{
  pmap_entry *ent;
  for(ent = pmap_first(env->border_heads); ent; ent = pmap_next(env->border_heads)) {
    /* ir_printf("checking border list of block %+F\n", ent->key); */
    check_border_list(ent->value);
  }
}


/**
 * Add an interval border to the list of a block's list
 * of interval border.
 * @note You always have to create the use before the def.
 * @param env The environment.
 * @param head The list head to enqueue the borders.
 * @param irn The node (value) the border belongs to.
 * @param pressure The pressure at this point in time.
 * @param step A time step for the border.
 * @param is_def Is the border a use or a def.
 * @return The created border.
 */
static INLINE border_t *border_add(be_chordal_env_t *env, struct list_head *head,
                        ir_node *irn, unsigned step, unsigned pressure,
                        unsigned is_def, unsigned is_real)
{
        border_t *b;

        if(!is_def) {
                border_t *def;

                b = obstack_alloc(&env->obst, sizeof(*b));

                /* also allocate the def and tie it to the use. */
                def = obstack_alloc(&env->obst, sizeof(*def));
    memset(def, 0, sizeof(*def));
                b->other_end = def;
                def->other_end = b;

                /*
                 * Set the link field of the irn to the def.
                 * This strongly relies on the fact, that the use is always
                 * made before the def.
                 */
                set_irn_link(irn, def);

                b->magic = BORDER_FOURCC;
                def->magic = BORDER_FOURCC;
        }

        /*
         * If the def is encountered, the use was made and so was the
         * the def node (see the code above). It was placed into the
         * link field of the irn, so we can get it there.
         */
        else {
                b = get_irn_link(irn);

                assert(b && b->magic == BORDER_FOURCC && "Illegal border encountered");
        }

        b->pressure = pressure;
        b->is_def = is_def;
        b->is_real = is_real;
        b->irn = irn;
        b->step = step;
        list_add_tail(&b->list, head);
        DBG((dbg, LEVEL_5, "\t\t%s adding %+F, step: %d\n",
                                is_def ? "def" : "use", irn, step));


        return b;
}

static INLINE int has_reg_class(const be_chordal_env_t *env, const ir_node *irn)
{
  return arch_irn_has_reg_class(env->session_env->main_env->arch_env, irn, arch_pos_make_out(0), env->cls);
}

/**
 * Annotate the register pressure to the nodes and compute
 * the liveness intervals.
 * @param block The block to do it for.
 * @param env_ptr The environment.
 */
static void pressure(ir_node *block, void *env_ptr)
{
/* Convenience macro for a def */
#define border_def(irn, step, real) \
        border_add(env, head, irn, step, pressure--, 1, real)

/* Convenience macro for a use */
#define border_use(irn, step, real) \
        border_add(env, head, irn, step, ++pressure, 0, real)

        be_chordal_env_t *env = env_ptr;
        bitset_t *live = env->live;
        ir_node *irn;

        int i, n;
        unsigned step = 0;
        unsigned pressure = 0;
        struct list_head *head;
        pset *live_in = put_live_in(block, pset_new_ptr_default());
        pset *live_end = put_live_end(block, pset_new_ptr_default());

        DBG((dbg, LEVEL_1, "Computing pressure in block %+F\n", block));
        bitset_clear_all(live);

        /* Set up the border list in the block info */
        head = obstack_alloc(&env->obst, sizeof(*head));
        INIT_LIST_HEAD(head);
  assert(pmap_get(env->border_heads, block) == NULL);
        pmap_insert(env->border_heads, block, head);

        /*
         * Make final uses of all values live out of the block.
         * They are necessary to build up real intervals.
         */
        for(irn = pset_first(live_end); irn; irn = pset_next(live_end)) {
                DBG((dbg, LEVEL_3, "\tMaking live: %+F/%d\n", irn, get_irn_graph_nr(irn)));
                bitset_set(live, get_irn_graph_nr(irn));
                if(has_reg_class(env, irn))
                        border_use(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) {
                DBG((dbg, LEVEL_1, "\tinsn: %+F, pressure: %d\n", irn, pressure));
                DBG((dbg, LEVEL_2, "\tlive: %b\n", live));

            /*
             * If the node defines some value, which can put into a
             * register of the current class, make a border for it.
             */
                if(has_reg_class(env, irn)) {
                        bitset_pos_t elm;
                        int nr = get_irn_graph_nr(irn);

                        bitset_clear(live, nr);
                        border_def(irn, step, 1);

#ifdef BUILD_GRAPH
                        bitset_foreach(live, elm)
                                add_if(env, nr, (int) elm);
#endif
                }

                /*
                 * 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(has_reg_class(env, op)) {
                                        int nr = get_irn_graph_nr(op);

                                        DBG((dbg, LEVEL_4, "\t\tpos: %d, use: %+F\n", i, op));

                                        if(!bitset_is_set(live, nr)) {
                                                border_use(op, step, 1);
                                                bitset_set(live, nr);
                                        }
                                }
                        }
                }
                ++step;
        }

        /*
         * Add initial defs for all values live in.
         */
        for(irn = pset_first(live_in); irn; irn = pset_next(live_in)) {
                if(has_reg_class(env, irn)) {

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

                        /* Add the def */
                        border_def(irn, step, 0);
                }
        }


  del_pset(live_in);
  del_pset(live_end);
}

static void assign(ir_node *block, void *env_ptr)
{
        be_chordal_env_t *env = env_ptr;
        bitset_t *live = env->live;
        bitset_t *colors = env->colors;
        bitset_t *in_colors = env->in_colors;
  const arch_env_t *arch_env = env->session_env->main_env->arch_env;

        const ir_node *irn;
        border_t *b;
        struct list_head *head = get_block_border_head(env, block);
        pset *live_in = put_live_in(block, pset_new_ptr_default());



        bitset_clear_all(live);
        bitset_clear_all(colors);
        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"));
        list_for_each_entry(border_t, b, head, list) {
                DBG((dbg, LEVEL_4, "\t%s %+F/%d\n", b->is_def ? "def" : "use",
                                        b->irn, get_irn_graph_nr(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.
         */
        for(irn = pset_first(live_in); irn; irn = pset_next(live_in)) {
                if(has_reg_class(env, irn)) {
      const arch_register_t *reg = arch_get_irn_register(arch_env, irn, 0);
      int col;

      assert(reg && "Node must have been assigned a register");
                        col = arch_register_get_index(reg);

                        /* Mark the color of the live in value as used. */
                        bitset_set(colors, col);
                        bitset_set(in_colors, col);

                        /* Mark the value live in. */
                        bitset_set(live, get_irn_graph_nr(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) {
                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)) {
      const arch_register_t *reg;
                        int col = NO_COLOR;

                        DBG((dbg, LEVEL_4, "\tcolors in use: %b\n", colors));

      col = bitset_next_clear(colors, 0);
      reg = arch_register_for_index(env->cls, col);

      assert(arch_get_irn_register(arch_env, irn, 0) == NULL
          && "This node must not have been assigned a register yet");
                        assert(!bitset_is_set(live, nr) && "Value's definition must not have been encountered");

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

                        arch_set_irn_register(arch_env, irn, 0, reg);
                        DBG((dbg, LEVEL_1, "\tassigning register %s(%d) to %+F\n",
            arch_register_get_name(reg), col, irn));
                }

                /* Clear the color upon a use. */
                else if(!b->is_def) {
      const arch_register_t *reg = arch_get_irn_register(arch_env, irn, 0);
                        int col;

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

      col = arch_register_get_index(reg);
                        assert(bitset_is_set(live, nr) && "Cannot have a non live use");

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

  del_pset(live_in);
}

void be_ra_chordal_init(void)
{
        dbg = firm_dbg_register(DBG_CHORDAL);
        firm_dbg_set_mask(dbg, DBG_LEVEL);
}

be_chordal_env_t *be_ra_chordal(
    const be_main_session_env_t *session,
    const arch_register_class_t *cls)
{
  ir_graph *irg = session->irg;
        int node_count = get_graph_node_count(irg);
        int colors_n = arch_register_class_n_regs(cls);
        be_chordal_env_t *env = malloc(sizeof(*env));

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

        obstack_init(&env->obst);

#ifdef BUILD_GRAPH
        env->edges = new_set(if_edge_cmp, node_count);
        env->nodes = new_set(if_node_cmp, node_count);
#endif

  env->session_env = session;
        env->live = bitset_obstack_alloc(&env->obst, node_count);
        env->colors = bitset_obstack_alloc(&env->obst, colors_n);
        env->in_colors = bitset_obstack_alloc(&env->obst, colors_n);
        env->colors_n = colors_n;
        env->cls = cls;
        env->border_heads = pmap_create();

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

        /* Insert probable spills */
        be_ra_chordal_spill(env);

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

#ifdef DUMP_IFG
        dump_ifg(env);
#endif

#ifdef DUMP_INTERVALS
        {
                char buf[128];
        plotter_t *plotter;

                ir_snprintf(buf, sizeof(buf), "ifg_%s_%F.eps", cls->name, irg);
        plotter = new_plotter_ps(buf);

        draw_interval_tree(&draw_chordal_def_opts, env, plotter, arch_env, cls);
        plotter_free(plotter);
        }
#endif
        return env;
}

void be_ra_chordal_check(be_chordal_env_t *chordal_env) {
        const arch_env_t *arch_env = chordal_env->session_env->main_env->arch_env;
        struct obstack ob;
        pmap_entry *pme;
        ir_node **nodes, *n1, *n2;
        int i, o;

        /* Collect all irns */
        obstack_init(&ob);
        pmap_foreach(chordal_env->border_heads, pme) {
                border_t *curr;
                struct list_head *head = pme->value;
                list_for_each_entry(border_t, curr, head, list)
                        if (curr->is_def && curr->is_real)
                                if (arch_get_irn_reg_class(arch_env, curr->irn, arch_pos_make_out(0)) == chordal_env->cls)
                                        obstack_ptr_grow(&ob, curr->irn);
        }
        obstack_ptr_grow(&ob, NULL);
        nodes = (ir_node **) obstack_finish(&ob);

        /* Check them */
        for (i = 0, n1 = nodes[i]; n1; n1 = nodes[++i]) {
                const arch_register_t *n1_reg, *n2_reg;

                n1_reg = arch_get_irn_register(arch_env, n1, 0);
                if (!arch_reg_is_allocatable(arch_env, n1, arch_pos_make_out(0), n1_reg)) {
                        DBG((dbg, 0, "Register assigned to %+F is not allowed\n", n1));
                        assert(0 && "Register constraint does not hold");
                }
                for (o = i+1, n2 = nodes[o]; n2; n2 = nodes[++o]) {
                        n2_reg = arch_get_irn_register(arch_env, n2, 0);
                        if (nodes_interfere(chordal_env, n1, n2) && n1_reg == n2_reg) {
                                DBG((dbg, 0, "Values %+F and %+F interfere and have the same regiseter assigned\n", n1, n2));
                                assert(0 && "Interfering values have the same color!");
                        }
                }
        }
        obstack_free(&ob, NULL);
}

/* BETTER #ifdef BUILD_GRAPH --> faster version of checker with edges */

void be_ra_chordal_done(be_chordal_env_t *env)
{
#ifdef BUILD_GRAPH
        {
                if_node_t *ifn;
                for(ifn = set_first(env->nodes); ifn; ifn = set_next(env->nodes))
                        free(ifn->neighb);
                free(env->nodes);
                free(env->edges);
        }
#endif

  pmap_destroy(env->border_heads);
        obstack_free(&env->obst, NULL);
        free(env);
}



int nodes_interfere(const be_chordal_env_t *env, const ir_node *a, const ir_node *b)
{
#ifdef BUILD_GRAPH
        return are_connected(env, get_irn_graph_nr(a), get_irn_graph_nr(b));
#else
        return values_interfere(a, b);
#endif /* BUILD_GRAPH */
}

#ifdef BUILD_GRAPH

set *be_ra_get_ifg_edges(const be_chordal_env_t *env) {
        return env->edges;
}

set *be_ra_get_ifg_nodes(const be_chordal_env_t *env) {
        return env->nodes;
}

#endif