[libfirm] / ir / be / beirgmod.c

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

#include <stdlib.h>

#ifdef WIN32
#include <malloc.h>
#else
#include <alloca.h>
#endif

#include "hashptr.h"
#include "pdeq.h"
#include "pset.h"
#include "pmap.h"
#include "util.h"
#include "debug.h"

#include "irflag_t.h"
#include "ircons_t.h"
#include "irnode_t.h"
#include "ircons_t.h"
#include "irmode_t.h"
#include "irdom_t.h"
#include "iredges_t.h"
#include "irgopt.h"

#include "be_t.h"
#include "bearch.h"
#include "besched_t.h"
#include "belive_t.h"
#include "benode_t.h"
#include "beutil.h"

#include "beirgmod.h"

#define DBG_MODULE firm_dbg_register("firm.be.irgmod")
#define DBG_LEVEL SET_LEVEL_0

struct _dom_front_info_t {
  pmap *df_map;
};

/**
 * A wrapper for get_Block_idom.
 * This function returns the block itself, if the block is the start
 * block. Returning NULL would make any != comparison true which
 * suggests, that the start block is dominated by some other node.
 * @param bl The block.
 * @return The immediate dominator of the block.
 */
static INLINE ir_node *get_idom(ir_node *bl)
{
  ir_node *idom = get_Block_idom(bl);
  return idom == NULL ? bl : idom;
}

static void compute_df(ir_node *n, pmap *df_map)
{
  ir_node *c;
  const ir_edge_t *edge;
  pset *df = pset_new_ptr_default();

  /* Add local dominance frontiers */
  foreach_block_succ(n, edge) {
    ir_node *y = edge->src;

    if(get_idom(y) != n)
      pset_insert_ptr(df, y);
  }

  /*
   * Go recursively down the dominance tree and add all blocks
   * int the dominance frontiers of the children, which are not
   * dominated by the given block.
   */
  for(c = get_Block_dominated_first(n); c; c = get_Block_dominated_next(c)) {
    pset *df_c;
    ir_node *w;

    compute_df(c, df_map);
    df_c = pmap_get(df_map, c);

    for(w = pset_first(df_c); w; w = pset_next(df_c)) {
      if(get_idom(w) != n)
        pset_insert_ptr(df, w);
    }
  }

  pmap_insert(df_map, n, df);

}

dom_front_info_t *be_compute_dominance_frontiers(ir_graph *irg)
{
  dom_front_info_t *info = malloc(sizeof(*info));

  edges_assure(irg);
  info->df_map = pmap_create();
  compute_doms(irg);
  compute_df(get_irg_start_block(irg), info->df_map);

  return info;
}

void be_free_dominance_frontiers(dom_front_info_t *info)
{
  pmap_entry *ent;

  for(ent = pmap_first(info->df_map); ent; ent = pmap_next(info->df_map))
    del_pset(ent->value);

  pmap_destroy(info->df_map);
  free(info);
}

pset *be_get_dominance_frontier(dom_front_info_t *info, ir_node *block)
{
  return pmap_get(info->df_map, block);
}

static void determine_phi_blocks(pset *copies, pset* copy_blocks, pset *phi_blocks, dom_front_info_t *df_info)
{
        ir_node *bl;
        pdeq *worklist = new_pdeq();
        firm_dbg_module_t *dbg = DBG_MODULE;

        /*
        * Fill the worklist queue and the rest of the orig blocks array.
        */
        for(bl = pset_first(copy_blocks); bl; bl = pset_next(copy_blocks)) {
                pdeq_putr(worklist, bl);
        }

        while(!pdeq_empty(worklist)) {
                ir_node *bl = pdeq_getl(worklist);
                pset *df    = be_get_dominance_frontier(df_info, bl);

                ir_node *y;

                DBG((dbg, LEVEL_3, "dom front of %+F\n", bl));
                for(y = pset_first(df); y; y = pset_next(df))
                        DBG((dbg, LEVEL_3, "\t%+F\n", y));

                for(y = pset_first(df); y; y = pset_next(df)) {
                        if(!pset_find_ptr(phi_blocks, y)) {
                                pset_insert_ptr(phi_blocks, y);

                                /*
                                * Clear the link field of a possible phi block, since
                                * the possibly created phi will be stored there. See,
                                * search_def()
                                */
                                set_irn_link(y, NULL);

                                if(!pset_find_ptr(copy_blocks, y))
                                        pdeq_putr(worklist, y);

                        }
                }
        }

        del_pdeq(worklist);
}

/**
 * Find the copy of the given original node whose value is 'active'
 * at a usage.
 *
 * The usage is given as a node and a position. Initially, the given operand
 * points to a node for which copies were introduced. We have to find
 * the valid copy for this usage. This is done by travering the
 * dominance tree upwards. If the usage is a phi function, we start
 * traversing from the predecessor block which corresponds to the phi
 * usage.
 *
 * @param usage       The node which uses the original node.
 * @param pos         The position of the argument which corresponds to the original node.
 * @param copies      A set containing all node which are copies from the original node.
 * @param copy_blocks A set containing all basic block in which copies of the original node are located.
 * @param phis        A set where all created phis are recorded.
 * @param phi_blocks  A set of all blocks where Phis shall be inserted (iterated dominance frontier).
 * @param mode        The mode for the Phi if one has to be created.
 * @return            The valid copy for usage.
 */
static ir_node *search_def(ir_node *usage, int pos, pset *copies, pset *copy_blocks, pset *phis, pset *phi_blocks, ir_mode *mode)
{
        ir_node *curr_bl;
        ir_node *start_irn;
        firm_dbg_module_t *dbg = DBG_MODULE;

        curr_bl = get_nodes_block(usage);

        DBG((dbg, LEVEL_1, "Searching valid def for use %+F at pos %d\n", usage, pos));
        /*
        * If the usage is in a phi node, search the copy in the
        * predecessor denoted by pos.
        */
        if(is_Phi(usage)) {
                curr_bl = get_Block_cfgpred_block(curr_bl, pos);
                start_irn = sched_last(curr_bl);
        } else {
                start_irn = sched_prev(usage);
        }

        /*
         * Traverse the dominance tree upwards from the
         * predecessor block of the usage.
         */
        while(curr_bl != NULL) {

            /*
                 * If this block contains a copy, search the block
                 * instruction by instruction.
                 */
                if(pset_find_ptr(copy_blocks, curr_bl)) {
                        ir_node *irn;

                        /* Look at each instruction from last to first. */
                        sched_foreach_reverse_from(start_irn, irn) {

                                /* Take the first copy we find. */
                                if(pset_find_ptr(copies, irn))
                                        return irn;
                        }
                }

                if(pset_find_ptr(phi_blocks, curr_bl)) {
                        ir_node *phi = get_irn_link(curr_bl);

                        if(!phi) {
                                int i, n_preds = get_irn_arity(curr_bl);
                                ir_graph *irg = get_irn_irg(curr_bl);
                                ir_node **ins = xmalloc(n_preds * sizeof(ins[0]));

                                for(i = 0; i < n_preds; ++i)
                                        ins[i] = new_r_Unknown(irg, mode);

                                phi = new_r_Phi(irg, curr_bl, n_preds, ins, mode);
                                DBG((dbg, LEVEL_2, "\tcreating phi %+F in %+F\n", phi, curr_bl));

                                set_irn_link(curr_bl, phi);
                                sched_add_after(curr_bl, phi);
                                free(ins);

                                for(i = 0; i < n_preds; ++i) {
                                        ir_node *arg = search_def(phi, i, copies, copy_blocks, phis, phi_blocks, mode);
                                        DBG((dbg, LEVEL_2, "\t\t%+F(%d) -> %+F\n", phi, i, arg));
                                        set_irn_n(phi, i, arg);
                                }

                                if(phis)
                                        pset_insert_ptr(phis, phi);
                        }

                        return phi;
                }

                /* If were not done yet, look in the immediate dominator */
                curr_bl = get_Block_idom(curr_bl);
                if(curr_bl)
                        start_irn = sched_last(curr_bl);
        }

        return NULL;
}

static void fix_usages(pset *copies, pset *copy_blocks, pset *phi_blocks, pset *phis, pset *ignore_uses)
{
        firm_dbg_module_t *dbg = DBG_MODULE;
        int n_outs             = 0;

        struct obstack obst;
        ir_node *irn;
        int i;

        struct out {
                ir_node *irn;
                int pos;
        } *outs;

        obstack_init(&obst);

        /*
        * Put all outs into an array.
        * This is necessary, since the outs would be modified while
        * iterating on them what could bring the outs module in trouble.
        */
        for(irn = pset_first(copies); irn; irn = pset_next(copies)) {
                const ir_edge_t *edge;
                foreach_out_edge(irn, edge) {
                        if(!pset_find_ptr(ignore_uses, get_edge_src_irn(edge))) {
                                struct out tmp;
                                tmp.irn = get_edge_src_irn(edge);
                                tmp.pos = get_edge_src_pos(edge);
                                obstack_grow(&obst, &tmp, sizeof(tmp));
                                n_outs++;
                        }
                }
        }
        outs = obstack_finish(&obst);

        /*
         * Search the valid def for each out and set it.
         */
        for(i = 0; i < n_outs; ++i) {
                ir_node *irn  = outs[i].irn;
                int pos       = outs[i].pos;
                ir_mode *mode = get_irn_mode(get_irn_n(irn, pos));

                ir_node *def;

                def = search_def(irn, pos, copies, copy_blocks, phis, phi_blocks, mode);
                DBG((dbg, LEVEL_2, "\t%+F(%d) -> %+F\n", irn, pos, def));

                if(def != NULL)
                        set_irn_n(irn, pos, def);
        }

        obstack_free(&obst, NULL);
}

/**
 * Remove phis which are not necessary.
 * During place_phi_functions() phi functions are put on the dominance
 * frontiers blindly. However some of them will never be used (these
 * have at least one predecessor which is NULL, see search_def() for
 * this case). Since place_phi_functions() enters them into the
 * schedule, we have to remove them from there.
 *
 * @param copies The set of all copies made (including the phi functions).
 */
static void remove_odd_phis(pset *copies, pset *unused_copies)
{
  ir_node *irn;

  for(irn = pset_first(copies); irn; irn = pset_next(copies)) {
    if(is_Phi(irn)) {
      int i, n;
      int illegal = 0;

      assert(sched_is_scheduled(irn) && "phi must be scheduled");
      for(i = 0, n = get_irn_arity(irn); i < n && !illegal; ++i)
        illegal = get_irn_n(irn, i) == NULL;

      if(illegal)
        sched_remove(irn);
    }
  }

  for(irn = pset_first(unused_copies); irn; irn = pset_next(unused_copies)) {
                sched_remove(irn);
        }
}

void be_ssa_constr_phis_ignore(dom_front_info_t *info, int n, ir_node *nodes[], pset *phis, pset *ignore_uses)
{
        pset *irns = pset_new_ptr(n);
        int i;

        for(i = 0; i < n; ++i)
                pset_insert_ptr(irns, nodes[i]);
        be_ssa_constr_set_phis_ignore(info, irns, phis, ignore_uses);
        del_pset(irns);
}

void be_ssa_constr_ignore(dom_front_info_t *info, int n, ir_node *nodes[], pset *ignore_uses)
{
        be_ssa_constr_phis_ignore(info, n, nodes, NULL, ignore_uses);
}

void be_ssa_constr(dom_front_info_t *info, int n, ir_node *nodes[])
{
        pset *empty_set = be_empty_set();
        assert(pset_count(empty_set) == 0);
        be_ssa_constr_ignore(info, n, nodes, empty_set);
}

void be_ssa_constr_set_phis_ignore(dom_front_info_t *df, pset *nodes, pset *phis, pset *ignore_uses)
{
        int n                  = pset_count(nodes);
        pset *blocks           = pset_new_ptr(n);
        pset *phi_blocks       = pset_new_ptr(n);
        int save_optimize      = get_optimize();
        int save_normalize     = get_opt_normalize();
        firm_dbg_module_t *dbg = DBG_MODULE;

        ir_node *irn;

        firm_dbg_set_mask(dbg, DBG_LEVEL);
        DBG((dbg, LEVEL_1, "Introducing following copies for:\n"));

        /* Fill the sets. */
        for(irn = pset_first(nodes); irn; irn = pset_next(nodes)) {
                ir_node *bl = get_nodes_block(irn);
                pset_insert_ptr(blocks, bl);
                DBG((dbg, LEVEL_1, "\t%+F in %+F\n", irn, bl));
        }

        /*
        * Disable optimization so that the phi functions do not
        * disappear.
        */
        set_optimize(0);
        set_opt_normalize(0);

        /*
        * Place the phi functions and reroute the usages.
        */
        determine_phi_blocks(nodes, blocks, phi_blocks, df);
        fix_usages(nodes, blocks, phi_blocks, phis, ignore_uses);

        /* reset the optimizations */
        set_optimize(save_optimize);
        set_opt_normalize(save_normalize);

        del_pset(phi_blocks);
        del_pset(blocks);

}

void be_ssa_constr_set_phis(dom_front_info_t *df, pset *nodes, pset *phis)
{
        pset *empty_set = be_empty_set();
        assert(pset_count(empty_set) == 0);

        be_ssa_constr_set_phis_ignore(df, nodes,phis, empty_set);
}

void be_ssa_constr_set_ignore(dom_front_info_t *df, pset *nodes, pset *ignore_uses)
{
        be_ssa_constr_set_phis_ignore(df, nodes, NULL, ignore_uses);
}

void be_ssa_constr_set(dom_front_info_t *info, pset *nodes)
{
        pset *empty_set = be_empty_set();
        assert(pset_count(empty_set) == 0);
        be_ssa_constr_set_ignore(info, nodes, empty_set);
}