Added prototype for phi_ops_interfere

[libfirm] / ir / be / bephicoal.c

/**
 * @author Daniel Grund
 * @date 04.01.2005
 */

#include <stdlib.h>

#include "obst.h"
#include "set.h"
#include "pset.h"
#include "bitset.h"
#include "debug.h"
#include "irouts.h"
#include "irdom.h"

#include "bechordal.h"
#include "belive.h"
#include "bera_t.h"
#include "bephicongr_t.h"
#include "bephicoal_t.h"

#define DEBUG_LVL SET_LEVEL_3
#define MAX_COLORS 16

/* some things for readable code */
#define CHANGE_SAVE NULL
#define CHANGE_IMPOSSIBLE (ir_node *)1
#define CHANGE_NYI (ir_node *)2
typedef enum _perform_t { dryrun = 0, perform = 1 } perform_t;
/* TODO: ask/check if additional ir_node-space is initialized with 0000 */
//#define belongs_to_a_phi_class(n) (get_irn_phi_info(n)->phi)
//#define is_color_free(bl,col) (!bitset_is_set(get_ra_block_info(bl)->used_colors, col))

typedef struct _phi_unit_t {
        unsigned char count;
        unsigned char phi_count;

        /* 1 phi */
        ir_node **members;                      /**< [0] is the phi node. [1..count-1] the arguments of the phi not interfering with it */
        int *colors;                            /**< [i] is the color to set for members[i]. [i] == NO_COLOR means dont change anything for members[i]*/
        /* TODO: perhaps unneccessary */
        char *is_live_in;                       /**< [i]==1 means members[i] is live-in in (all of) its cf-pred-blocks of the phi node */
} phi_unit_t;


static firm_dbg_module_t *dbgphi = NULL;
int XXX_copies=0, XXX_count=0;


/**
 * Contains ir_nodes of phi-classes whose colors may change unlimited times.
 * These nodes are not optimizable, so there is no need to pin their color.
 */
static pset *free_nodes = NULL;

/**
 * Contains already optimized ir_nodes of phi-classes fully processed.
 * So one can perform a check not to switch them twice or more.
 */
static pset *pinned_global = NULL;

/**
 * Contains optimized ir_nodes of the phi-classes
 * currently optimized. So one can perform a check not to switch them
 * twice or more.
 */
static pset *pinned_local = NULL;

/**
 * Contains the hypothetic colors of currently processed phi unit
 */
static set *hyp_cols = NULL;

typedef struct _hyp_col_t {
        ir_node *irn;
        int color;
} hyp_col_t;

int set_cmp_hyp_col_t(const void *x, const void *y, size_t size) {
        return ((hyp_col_t *)x)->irn != ((hyp_col_t *)y)->irn;
}


/**
 * @return The hypothetic color of the irn if available.
 *         Otherwise the current color of it.
 */
static INLINE int get_hyp_color(ir_node *irn) {
        hyp_col_t hc;
        hyp_col_t *found;
        hc.irn = irn;
        found = set_find(hyp_cols, &hc, sizeof(hc), HASH_PTR(irn));
        if (found)
                return found->color;
        else
                return get_irn_color(irn);
}

/**
 * Sets the hypothetic color of an irn
 */
static INLINE void set_hyp_color(ir_node *irn, int color) {
        hyp_col_t hc;
        hyp_col_t *found;
        hc.irn = irn;
        found = set_find(hyp_cols, &hc, sizeof(hc), HASH_PTR(irn));
        if (found)
                found->color = color;
        else {
                hc.color = color;
                set_insert(hyp_cols, &hc, sizeof(hc), HASH_PTR(irn));
        }
}



/**
 * Variable neede in _color_irn.
 * Not on stack, because never changed during recursion.
 */
static perform_t _color_irn_perform;

/**
 * Get all nodes which conflict with the color-setting of a node, because they
 * have the same color and are living together at some point in time.
 * @param irn The ir_node to find conflicting nodes for
 * @param color The color the conflicting nodes must have
 * @param bl  The root-block of the dom-sub-tree to start the search from.
 * @param exc An exceptional node which is never added to the result set of conflicting nodes
 * @param res An obstack to grow the resulting nodes on.
 */
static void get_conflicting_nodes(const ir_node *irn, int color, ir_node *bl, const ir_node *exc, struct obstack *res) {
        struct obstack q;
        int in, out;

        /* setup the queue */
        obstack_init(&q);
        obstack_ptr_grow(&q, bl);
        in = 1;
        out = 0;

        /* process the queue */
        while (out < in) {
                ir_node *curr_bl, *sub_bl;
                int i, max;

                curr_bl = ((ir_node **)obstack_base(&q))[out++];

                /* Add to the result all nodes in the block which live in target color
                 * and interfere with the irn */
                for (i = 0, max = get_irn_n_outs(curr_bl); i < max; ++i) {
                        ir_node *n = get_irn_out(curr_bl, i);
                        int n_col;
                        if (!is_allocatable_irn(n))
                                continue;
                        if (_color_irn_perform == perform)
                                n_col = get_irn_color(n);
                        else
                                n_col = get_hyp_color(n);

                        if (n != exc && get_hyp_color(n) == color && phi_ops_interfere(irn, n))
                                obstack_ptr_grow(res, n);
                }

                /* If irn lives out check i-dominated blocks where the irn lives in */
                /* Fill the queue */
                if (is_live_out(curr_bl, irn)) {
                        dominates_for_each(curr_bl, sub_bl)
                                if (is_live_in(sub_bl, irn)) {
                                        obstack_ptr_grow(&q, sub_bl);
                                        in++;
                                }
                }
        }

        obstack_free(&q, NULL);
}


/**
 * Tries to set the color of @p n to @p col. Performs recoloring of other nodes
 * as required to preserve correctness. Recursive.
 * @param  irn The node to set the color for
 * @param  col The color to set.
 * @param  trigger The irn that caused the wish to change the color of the irn
 * @return CHANGE_SAVE iff setting the color is possible.
 *         CHANGE_IMPOSSIBLE iff conflicts with reg-constraintsis occured.
 *         Else the conflicting ir_node is returned.
 *
 * ASSUMPTION: Assumes that a life range of a single value can't be spilt into
 *                         several smaller intervals where other values can live in between.
 */
static ir_node *_color_irn(ir_node *irn, int col, const ir_node *trigger) {
        ir_node *res;
        struct obstack confl_ob;
        ir_node **confl, *cn;
        ir_node *irn_bl;
        int i, irn_col;
        if (_color_irn_perform == perform)
                irn_col = get_irn_color(irn);
        else
                irn_col = get_hyp_color(irn);

        obstack_init(&confl_ob);

        if (irn_col == col)
                goto ret_save;

        if (pset_find_ptr(pinned_global, irn)) {
                DBG((dbgphi, LEVEL_3, "\t\t\t%n \t~~> %n := %d: Pinned other\n", trigger, irn, col));
                res = irn;
                goto ret_confl;
        }

        if (pset_find_ptr(pinned_local, irn)) {
                DBG((dbgphi, LEVEL_3, "\t\t\t%n \t~~> %n := %d: Pinned current\n", trigger, irn, col));
                res = irn;
                goto ret_confl;
        }

        /* process all nodes which would conflict with this change */
        irn_bl = get_nodes_block(irn);
        get_conflicting_nodes(irn, col, irn_bl, trigger, &confl_ob);
        obstack_ptr_grow(&confl_ob, NULL);
        confl = (ir_node **) obstack_finish(&confl_ob);

        for (i = 0, cn = confl[0]; cn; cn = confl[++i]) {
                ir_node *sub_res;

                /* for now don't let the changes spread in root-direction of the dom-tree */
                if (is_live_in(irn_bl, cn)) {
                        DBG((dbgphi, LEVEL_3, "\t\t\t%n \t~~> %n := %d: NYI %n\n", trigger, irn, col, cn));
                        res = CHANGE_NYI;
                        goto ret_confl;
                }

                /* try to color the conflicting node cn with the color of the irn itself */
                DBG((dbgphi, LEVEL_3, "\t\t\t%n \t~~> %n := %d: Subcheck\n", trigger, irn, col));
                sub_res = _color_irn(cn, irn_col, irn);
                if (sub_res != CHANGE_SAVE) {
                        res = sub_res;
                        goto ret_confl;
                }
        }
        /* if we arrive here all sub changes can be applied,
         * so it is save to change this irn */

ret_save:
        DBG((dbgphi, LEVEL_2, "\t\t\t%n \t~~> %n := %d: Save\n", trigger, irn, col));
        obstack_free(&confl_ob, NULL);
        if (_color_irn_perform == perform)
                set_irn_color(irn, col);
        else
                set_hyp_color(irn, col);
        return CHANGE_SAVE;

ret_confl:
        DBG((dbgphi, LEVEL_2, "\t\t\t%n \t~~> %n := %d: Conflict\n", trigger, irn, col));
        obstack_free(&confl_ob, NULL);
        assert(!_color_irn_perform && "When applying changes these must be save, but if you reach here they aren't!");
        return res;
}


static ir_node *color_irn(ir_node *irn, int col, perform_t do_what) {
        ir_node *res;

        _color_irn_perform = do_what;
        res = _color_irn(irn, col, irn);

        if (res == CHANGE_SAVE && !pset_find_ptr(free_nodes, irn)) {
                if (do_what == perform) {
                        DBG((dbgphi, LEVEL_2, "\t\t\t\t\t @G %n\n", irn));
                        pset_insert_ptr(pinned_global, irn);
                } else {
                        DBG((dbgphi, LEVEL_2, "\t\t\t\t\t @L %n\n", irn));
                        pset_insert_ptr(pinned_local, irn);
                }
        }
        return res;
}


/**
 * Tries to set as much members of a phi unit as possible to color @p col.
 * - Each change taken alone is guaranteed to be conflict free.
 * - _If_ all members are neither live-in nor live-out in their cf-pred-blocks
 *   _then_ all changes together can be applied conflict free.
 * - _If_ there is a member, which is live-in or live-out in its cf-pred-block
 *    of the phi node, it is possible that all changes together will conflict.
 * TODO: Check above comment with swapping complete colors in mind
 * TODO: Write sth. about dom-tree influence on this.
 */
static int try_colors(phi_unit_t *pu, int col, int b_size) {
        struct obstack ob;
        int i, o, cand_size, mis_size;
        ir_node **cand, **mis;

        obstack_init(&ob);
        pinned_local = pset_new_ptr(8);
        hyp_cols = new_set(set_cmp_hyp_col_t, 8);

        /* first init pessimistically, so we can just return
         * if we see there wont be a better result */
        mis_size = 0;
        for (i = 0; i < pu->count; ++i)
                pu->colors[i] = NO_COLOR;

        /* For all members check if color would be possible.
         * Does not check if color is possible in combination with
         * other members colors being set */
        cand_size = 0;
        for (i = 0; i < pu->count; ++i) {
                DBG((dbgphi, 1, "\t\t    Testing %n\n", pu->members[i]));
                if (color_irn(pu->members[i], col, dryrun) == CHANGE_SAVE) {
                        DBG((dbgphi, 1, "\t\t\tAdding to cand\n"));
                        obstack_ptr_grow(&ob, pu->members[i]);
                        cand_size++;
                } else {
                        DBG((dbgphi, 1, "\t\t\tImpossible\n"));
                }
                /* if color is not possible for the phi node then exit (phi comes first)*/
                if (cand_size == 0)
                        goto ret;
        }
        cand = obstack_finish(&ob);

        /* shortcut: if cand is worse than best then mis wont be better. */
        if (cand_size < b_size)
                goto ret;

        /* now take the candidates cand and determine a max independent set
         * with respect to edges representing live range interference */
        /* TODO: make this 'un-greedy' */
        DBG((dbgphi, 1, "\t\t    Max indep set\n"));
        for (i = 0; i < cand_size; ++i) {
                int intf_det = 0;
                for (o = 0; o < mis_size; ++o) {
                        mis = (ir_node**) obstack_base(&ob);
                        if (phi_ops_interfere(cand[i], mis[o])) {
                                intf_det = 1;
                                break;
                        }
                }

                if (!intf_det) {
                        DBG((dbgphi, 1, "\t\t\tAdding to mis %n\n", cand[i]));
                        obstack_ptr_grow(&ob, cand[i]);
                        mis_size++;
                }
        }
        mis = obstack_finish(&ob);

        /* Now set the colors of all nodes in the mis to col.
         * HINT: Set the color of all nodes, even if one has the same color already */
        for (i = 0; i < pu->count; ++i)
                for (o = 0; o < mis_size; ++o)
                        if (pu->members[i] == mis[o])
                                pu->colors[i] = col;

ret:
        del_set(hyp_cols);
        del_pset(pinned_local);
        obstack_free(&ob, NULL);
        return mis_size;
}


/**
 * Sets the colors of members[i] to colors[i].
 * All changes togehter must be conflict free.
 */
static void set_colors(phi_unit_t *pu) {
        int i;

        for (i = 0; i < pu->count; ++i)
                if (pu->colors[i] != NO_COLOR)
                        color_irn(pu->members[i], pu->colors[i], perform);
}


/**
 * Tries to re-allocate colors of this phi-class, to achieve a lower number of
 * copies placed during phi destruction. Optimized version. Works only for
 * phi-classes/phi-units with exactly 1 phi node, which is the case for approx.
 * 80% of all phi classes.
 */
static void coalesce_1_phi(phi_unit_t *pu) {
        int *b_colors, b_size, b_color;
        int i, size, col;

        b_colors = malloc(pu->count * sizeof(*b_colors));

        /* init best search result */
        b_size = 0;
        b_color = NO_COLOR;
        for (i = 0; i < pu->count; ++i)
                b_colors[i] = NO_COLOR;

        /* find optimum of all colors */
        for (col = MAX_COLORS-1; col >= 0; --col) {
                DBG((dbgphi, 1, "\tTrying color %d\n", col));
                size = try_colors(pu, col, b_size);

                /* did we find a better max ind. set? */
                if (size > b_size) {
                        b_size = size;
                        b_color = col;
                        memcpy(b_colors, pu->colors, pu->count * sizeof(*b_colors));
                        DBG((dbgphi, 1, "\t!! Better size: %d\n", b_size));
                }

                /* shortcut: if all members can be colored we are content */
                if (b_size == pu->count)
                        break;
        }
        DBG((dbgphi, 1, "\tBest color: %d  Copies: %d/%d\n", b_color, pu->count-b_size, pu->count));
        XXX_copies += pu->count-b_size;
        XXX_count += pu->count;
        if (b_color == NO_COLOR)
                goto ret;

        /* now apply the found optimum */
        memcpy(pu->colors, b_colors, pu->count * sizeof(*b_colors));
        set_colors(pu);

ret:
        free(b_colors);
}


/**
 * Tries to re-allocate colors of this phi-class, to achieve a lower number of
 * copies placed during phi destruction. General purpose version.
 */
static void coalesce_n_phi(phi_unit_t *pu) {
        DBG((dbgphi, 1, "\n"));
        /* TODO */
}


/**
 * Prepares a phi class for further processing as a phi unit.
 * @param pc The phi class to prepare.
 * @return A so called phi unit containing some prepared informations
 *         needed by the following coalescing phase.
 */
static phi_unit_t *new_phi_unit(pset *pc) {
        phi_unit_t *pu;
        ir_node *n, *phi = NULL;

        /* get the phi count of this class */
        pu = malloc(sizeof(*pu));
        pu->phi_count = 0;
        for (n = pset_first(pc); n; n = pset_next(pc))
                if (is_Phi(n)) {
                        phi = n;
                        pu->phi_count++;
                }

        if (pu->phi_count == 1) {
                ir_node **tmp, *phi_block;
                int i, max;
                struct obstack ob;

                obstack_init(&ob);

                /* build member set not containing phi interferers */
                DBG((dbgphi, 1, "Phi-1 class:\n"));
                pu->count = 1; /*for the phi*/
                for (n = pset_first(pc); n; n = pset_next(pc)) {
                        if (is_Phi(n))
                                continue;
                        if (!phi_ops_interfere(phi, n)) {
                                DBG((dbgphi, 1, "\tAdding to members: %n\n", n));
                                obstack_ptr_grow(&ob, n);
                                pu->count++;
                        } else {
                                DBG((dbgphi, 1, "\tPhi interferer: %n\n", n));
                                pset_insert_ptr(free_nodes, n);
                        }
                }
                tmp = obstack_finish(&ob);
                pu->members = malloc(pu->count * sizeof(*pu->members));
                pu->members[0] = phi;
                memcpy(&pu->members[1], tmp, (pu->count-1) * sizeof(*tmp));

                /* init of colors array */
                pu->colors = malloc(pu->count * sizeof(*pu->colors));

                /* live-in analysis */
                /* HINT: It is possible that a node occurs twice as arg of a phi,
                 * one time being live-in, and another time not being live-in.
                 */
                pu->is_live_in = calloc(pu->count, sizeof(*pu->is_live_in));
                phi_block = get_nodes_block(phi);
                for (i = 0, max = get_irn_arity(phi); i < max; ++i) {
                        int midx, o;
                ir_node *arg, *block_ith_pred;

                arg = get_irn_n(phi, i);
                        block_ith_pred = get_nodes_block(get_irn_n(phi_block, i));

                        /* find the arg in the members array */
                        midx = -1;
                        for (o = 0; o < pu->count; ++o)
                                if (pu->members[o] == arg) {
                                        midx = o;
                                        break;
                                }
                        if (midx == -1)
                                continue;

                        if (is_live_in(block_ith_pred, arg)) {
                                pu->is_live_in[midx] |= 1;
                                DBG((dbgphi, 1, "\t%n is live-in in %n\n", arg, block_ith_pred));
                        }
                }

                obstack_free(&ob, NULL);
        } else {
                DBG((dbgphi, 1, "Phi-n class:\n"));
                /* TODO */
        }

        DBG((dbgphi, 1, "\n"));
        return pu;
}


/**
 * Deletes a phi unit
 */
static void free_phi_unit(phi_unit_t *pu) {
        if (pu->phi_count == 1) {
                free(pu->members);
                free(pu->colors);
                free(pu->is_live_in);
        } else {
                /* TODO */
        }
        free(pu);
}


void be_phi_coalesce(pset *all_phi_classes) {
        pset *pc;

        pinned_global = pset_new_ptr(256);
        free_nodes = pset_new_ptr(64);

        for (pc = pset_first(all_phi_classes); pc; pc = pset_next(all_phi_classes)) {
                phi_unit_t *pu = new_phi_unit(pc);
                if (pu->phi_count == 1)
                        coalesce_1_phi(pu);
                else
                        coalesce_n_phi(pu);
                free_phi_unit(pu);
        }

        DBG((dbgphi, 1, "Copies: %d / %d\n", XXX_copies, XXX_count));

        del_pset(free_nodes);
        del_pset(pinned_global);
}


void be_phi_coal_init(void) {
        dbgphi = firm_dbg_register("Phi coalescing");
        firm_dbg_set_mask(dbgphi, DEBUG_LVL);
}