[libfirm] / ir / be / belive.c

/*
 * This file is part of libFirm.
 * Copyright (C) 2012 University of Karlsruhe.
 */

/**
 * @file
 * @brief       Interblock liveness analysis.
 * @author      Sebastian Hack
 * @date        06.12.2004
 */
#include "config.h"

/* statev is expensive here, only enable when needed */
#define DISABLE_STATEV

#include "iredges_t.h"
#include "irgwalk.h"
#include "irprintf.h"
#include "irdump_t.h"
#include "irnodeset.h"

#include "absgraph.h"
#include "statev_t.h"
#include "be_t.h"
#include "bearch.h"
#include "beutil.h"
#include "belive_t.h"
#include "besched.h"
#include "bemodule.h"

DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)

#define LV_STD_SIZE             64

int (be_is_live_in)(const be_lv_t *lv, const ir_node *block, const ir_node *irn)
{
        return _be_is_live_xxx(lv, block, irn, be_lv_state_in);
}

int (be_is_live_out)(const be_lv_t *lv, const ir_node *block, const ir_node *irn)
{
        return _be_is_live_xxx(lv, block, irn, be_lv_state_out);
}

int (be_is_live_end)(const be_lv_t *lv, const ir_node *block, const ir_node *irn)
{
        return _be_is_live_xxx(lv, block, irn, be_lv_state_end);
}

static inline unsigned _be_liveness_bsearch(be_lv_info_t *arr, const ir_node *node)
{
        be_lv_info_t *payload = arr + 1;

        unsigned n   = arr[0].head.n_members;
        unsigned res = 0;
        int lo       = 0;
        int hi       = n;

        if (n == 0)
                return 0;

        do {
                int md           = lo + ((hi - lo) >> 1);
                ir_node *md_node = payload[md].node.node;

                if (node > md_node)
                        lo = md + 1;
                else if (node < md_node)
                        hi = md;
                else {
                        res = md;
                        break;
                }

                res = lo;
        } while (lo < hi);

        return res;
}

be_lv_info_node_t *be_lv_get(const be_lv_t *li, const ir_node *bl,
                             const ir_node *irn)
{
        be_lv_info_t *irn_live;
        be_lv_info_node_t *res = NULL;

        stat_ev_tim_push();
        irn_live = ir_nodehashmap_get(be_lv_info_t, &li->map, bl);
        if (irn_live != NULL) {
                /* Get the position of the index in the array. */
                int pos = _be_liveness_bsearch(irn_live, irn);

                /* Get the record in question. 1 must be added, since the first record contains information about the array and must be skipped. */
                be_lv_info_node_t *rec = &irn_live[pos + 1].node;

                /* Check, if the irn is in deed in the array. */
                if (rec->node == irn)
                        res = rec;
        }
        stat_ev_tim_pop("be_lv_get");

        return res;
}

static be_lv_info_node_t *be_lv_get_or_set(be_lv_t *li, ir_node *bl,
                                           ir_node *irn)
{
        be_lv_info_t *irn_live = ir_nodehashmap_get(be_lv_info_t, &li->map, bl);
        if (irn_live == NULL) {
                irn_live = OALLOCNZ(&li->obst, be_lv_info_t, LV_STD_SIZE);
                irn_live[0].head.n_size = LV_STD_SIZE-1;
                ir_nodehashmap_insert(&li->map, bl, irn_live);
        }

        /* Get the position of the index in the array. */
        unsigned pos = _be_liveness_bsearch(irn_live, irn);

        /* Get the record in question. 1 must be added, since the first record contains information about the array and must be skipped. */
        be_lv_info_node_t *res = &irn_live[pos + 1].node;

        /* Check, if the irn is in deed in the array. */
        if (res->node != irn) {
                be_lv_info_t *payload;
                unsigned n_members = irn_live[0].head.n_members;
                unsigned n_size    = irn_live[0].head.n_size;
                unsigned i;

                if (n_members + 1 >= n_size) {
                        /* double the array size. Remember that the first entry is
                         * metadata about the array and not a real array element */
                        unsigned old_size_bytes  = (n_size + 1) * sizeof(irn_live[0]);
                        unsigned new_size        = (2 * n_size) + 1;
                        size_t   new_size_bytes  = new_size * sizeof(irn_live[0]);
                        be_lv_info_t *nw = OALLOCN(&li->obst, be_lv_info_t, new_size);
                        memcpy(nw, irn_live, old_size_bytes);
                        memset(((char*) nw) + old_size_bytes, 0,
                               new_size_bytes - old_size_bytes);
                        nw[0].head.n_size = new_size - 1;
                        irn_live = nw;
                        ir_nodehashmap_insert(&li->map, bl, nw);
                }

                payload = &irn_live[1];
                for (i = n_members; i > pos; --i) {
                        payload[i] = payload[i - 1];
                }

                ++irn_live[0].head.n_members;

                res        = &payload[pos].node;
                res->node  = irn;
                res->flags = 0;
        }

        return res;
}

/**
 * Removes a node from the list of live variables of a block.
 * @return 1 if the node was live at that block, 0 if not.
 */
static int be_lv_remove(be_lv_t *li, const ir_node *bl,
                        const ir_node *irn)
{
        be_lv_info_t *irn_live = ir_nodehashmap_get(be_lv_info_t, &li->map, bl);

        if (irn_live != NULL) {
                unsigned n   = irn_live[0].head.n_members;
                unsigned pos = _be_liveness_bsearch(irn_live, irn);
                be_lv_info_t *payload  = irn_live + 1;
                be_lv_info_node_t *res = &payload[pos].node;

                /* The node is in deed in the block's array. Let's remove it. */
                if (res->node == irn) {
                        unsigned i;

                        for (i = pos + 1; i < n; ++i)
                                payload[i - 1] = payload[i];

                        payload[n - 1].node.node  = NULL;
                        payload[n - 1].node.flags = 0;

                        --irn_live[0].head.n_members;
                        DBG((dbg, LEVEL_3, "\tdeleting %+F from %+F at pos %d\n", irn, bl, pos));
                        return 1;
                }
        }

        return 0;
}

static struct {
        be_lv_t  *lv;         /**< The liveness object. */
        ir_node  *def;        /**< The node (value). */
        ir_node  *def_block;  /**< The block of def. */
} re;

/**
 * Mark a node (value) live out at a certain block. Do this also
 * transitively, i.e. if the block is not the block of the value's
 * definition, all predecessors are also marked live.
 * @param block The block to mark the value live out of.
 * @param state The liveness bits to set, either end or end+out.
 */
static void live_end_at_block(ir_node *const block, be_lv_state_t const state)
{
        be_lv_info_node_t *const n      = be_lv_get_or_set(re.lv, block, re.def);
        be_lv_state_t      const before = n->flags;

        assert(state == be_lv_state_end || state == (be_lv_state_end | be_lv_state_out));
        DBG((dbg, LEVEL_2, "marking %+F live %s at %+F\n", re.def, state & be_lv_state_out ? "end+out" : "end", block));
        n->flags |= state;

        /* There is no need to recurse further, if we where here before (i.e., any
         * live state bits were set before). */
        if (before != be_lv_state_none)
                return;

        /* Stop going up further, if this is the block of the definition. */
        if (re.def_block == block)
                return;

        DBG((dbg, LEVEL_2, "marking %+F live in at %+F\n", re.def, block));
        n->flags |= be_lv_state_in;

        for (int i = get_Block_n_cfgpreds(block); i-- != 0;) {
                ir_node *const pred_block = get_Block_cfgpred_block(block, i);
                live_end_at_block(pred_block, be_lv_state_end | be_lv_state_out);
        }
}

typedef struct lv_remove_walker_t {
        be_lv_t       *lv;
        const ir_node *irn;
} lv_remove_walker_t;


/**
 * Liveness analysis for a value.
 * Compute the set of all blocks a value is live in.
 * @param irn     The node (value).
 */
static void liveness_for_node(ir_node *irn)
{
        ir_node *const def_block = get_nodes_block(irn);

        re.def       = irn;
        re.def_block = def_block;

        /* Go over all uses of the value */
        foreach_out_edge(irn, edge) {
                ir_node *use = edge->src;
                ir_node *use_block;

                DBG((dbg, LEVEL_4, "%+F: use at %+F, pos %d in %+F\n", irn, use, edge->pos, get_block(use)));
                assert(get_irn_n(use, edge->pos) == irn);

                /*
                 * If the usage is no data node, skip this use, since it does not
                 * affect the liveness of the node.
                 */
                if (!is_liveness_node(use))
                        continue;

                /* Get the block where the usage is in. */
                use_block = get_nodes_block(use);

                /*
                 * If the use is a phi function, determine the corresponding block
                 * through which the value reaches the phi function and mark the
                 * value as live out of that block.
                 */
                if (is_Phi(use)) {
                        ir_node *pred_block = get_Block_cfgpred_block(use_block, edge->pos);
                        live_end_at_block(pred_block, be_lv_state_end);
                }

                /*
                 * Else, the value is live in at this block. Mark it and call live
                 * out on the predecessors.
                 */
                else if (def_block != use_block) {
                        int i;

                        be_lv_info_node_t *const n = be_lv_get_or_set(re.lv, use_block, irn);
                        DBG((dbg, LEVEL_2, "marking %+F live in at %+F\n", irn, use_block));
                        n->flags |= be_lv_state_in;

                        for (i = get_Block_n_cfgpreds(use_block) - 1; i >= 0; --i) {
                                ir_node *pred_block = get_Block_cfgpred_block(use_block, i);
                                live_end_at_block(pred_block, be_lv_state_end | be_lv_state_out);
                        }
                }
        }
}

static void lv_remove_irn_walker(ir_node *bl, void *data)
{
        lv_remove_walker_t *w = (lv_remove_walker_t*)data;
        be_lv_remove(w->lv, bl, w->irn);
}

/**
 * Walker, collect all nodes for which we want calculate liveness info
 * on an obstack.
 */
static void collect_liveness_nodes(ir_node *irn, void *data)
{
        ir_node **nodes = (ir_node**)data;
        if (is_liveness_node(irn))
                nodes[get_irn_idx(irn)] = irn;
}

void be_liveness_compute_sets(be_lv_t *lv)
{
        int       i;
        int       n;

        if (lv->sets_valid)
                return;

        be_timer_push(T_LIVE);
        ir_nodehashmap_init(&lv->map);
        obstack_init(&lv->obst);

        n = get_irg_last_idx(lv->irg);
        ir_node **const nodes = NEW_ARR_FZ(ir_node*, n);

        /* inserting the variables sorted by their ID is probably
         * more efficient since the binary sorted set insertion
         * will not need to move around the data. */
        irg_walk_graph(lv->irg, NULL, collect_liveness_nodes, nodes);

        re.lv = lv;

        for (i = 0; i < n; ++i) {
                if (nodes[i] != NULL)
                        liveness_for_node(nodes[i]);
        }

        DEL_ARR_F(nodes);

        be_timer_pop(T_LIVE);

        lv->sets_valid = true;
}

void be_liveness_compute_chk(be_lv_t *lv)
{
        if (lv->lvc != NULL)
                return;
        lv->lvc = lv_chk_new(lv->irg);
}

void be_liveness_invalidate_sets(be_lv_t *lv)
{
        if (!lv->sets_valid)
                return;
        obstack_free(&lv->obst, NULL);
        ir_nodehashmap_destroy(&lv->map);
        lv->sets_valid = false;
}

void be_liveness_invalidate_chk(be_lv_t *lv)
{
        be_liveness_invalidate_sets(lv);

        if (lv->lvc == NULL)
                return;
        lv_chk_free(lv->lvc);
        lv->lvc = NULL;
}

be_lv_t *be_liveness_new(ir_graph *irg)
{
        be_lv_t *lv = XMALLOCZ(be_lv_t);

        lv->irg = irg;

        return lv;
}

void be_liveness_free(be_lv_t *lv)
{
        be_liveness_invalidate_sets(lv);
        be_liveness_invalidate_chk(lv);

        xfree(lv);
}

void be_liveness_remove(be_lv_t *lv, const ir_node *irn)
{
        if (lv->sets_valid) {
                lv_remove_walker_t w;

                /*
                 * Removes a single irn from the liveness information.
                 * Since an irn can only be live at blocks dominated by the block of its
                 * definition, we only have to process that dominance subtree.
                 */
                w.lv  = lv;
                w.irn = irn;
                dom_tree_walk(get_nodes_block(irn), lv_remove_irn_walker, NULL, &w);
        }
}

void be_liveness_introduce(be_lv_t *lv, ir_node *irn)
{
        /* Don't compute liveness information for non-data nodes. */
        if (lv->sets_valid && is_liveness_node(irn)) {
                re.lv = lv;
                liveness_for_node(irn);
        }
}

void be_liveness_update(be_lv_t *lv, ir_node *irn)
{
        be_liveness_remove(lv, irn);
        be_liveness_introduce(lv, irn);
}

void be_liveness_transfer(const arch_register_class_t *cls,
                          ir_node *node, ir_nodeset_t *nodeset)
{
        /* You should better break out of your loop when hitting the first phi
         * function. */
        assert(!is_Phi(node) && "liveness_transfer produces invalid results for phi nodes");

        be_foreach_definition(node, cls, value, req,
                ir_nodeset_remove(nodeset, value);
        );

        be_foreach_use(node, cls, in_req, op, op_req,
                ir_nodeset_insert(nodeset, op);
        );
}



void be_liveness_end_of_block(const be_lv_t *lv,
                              const arch_register_class_t *cls,
                              const ir_node *block, ir_nodeset_t *live)
{
        assert(lv->sets_valid && "live sets must be computed");
        be_lv_foreach_cls(lv, block, be_lv_state_end, cls, node) {
                ir_nodeset_insert(live, node);
        }
}



void be_liveness_nodes_live_before(be_lv_t const *const lv, arch_register_class_t const *const cls, ir_node const *const pos, ir_nodeset_t *const live)
{
        ir_node *const bl = get_nodes_block(pos);
        be_liveness_end_of_block(lv, cls, bl, live);
        sched_foreach_reverse(bl, irn) {
                be_liveness_transfer(cls, irn, live);
                if (irn == pos)
                        return;
        }
}

static void collect_node(ir_node *irn, void *data)
{
        struct obstack *obst = (struct obstack*)data;
        obstack_ptr_grow(obst, irn);
}

static void be_live_chk_compare(be_lv_t *lv, lv_chk_t *lvc)
{
        ir_graph *irg    = lv->irg;

        struct obstack obst;
        ir_node **nodes;
        ir_node **blocks;
        int i, j;

        obstack_init(&obst);

        irg_block_walk_graph(irg, collect_node, NULL, &obst);
        obstack_ptr_grow(&obst, NULL);
        blocks = (ir_node**)obstack_finish(&obst);

        irg_walk_graph(irg, collect_node, NULL, &obst);
        obstack_ptr_grow(&obst, NULL);
        nodes = (ir_node**)obstack_finish(&obst);

        stat_ev_ctx_push("be_lv_chk_compare");
        for (j = 0; nodes[j]; ++j) {
                ir_node *irn = nodes[j];
                if (is_Block(irn))
                        continue;

                for (i = 0; blocks[i]; ++i) {
                        ir_node *bl = blocks[i];
                        int lvr_in  = be_is_live_in (lv, bl, irn);
                        int lvr_out = be_is_live_out(lv, bl, irn);
                        int lvr_end = be_is_live_end(lv, bl, irn);

                        int lvc_in  = lv_chk_bl_in (lvc, bl, irn);
                        int lvc_out = lv_chk_bl_out(lvc, bl, irn);
                        int lvc_end = lv_chk_bl_end(lvc, bl, irn);

                        if (lvr_in - lvc_in != 0)
                                ir_fprintf(stderr, "live in  info for %+F at %+F differs: nml: %d, chk: %d\n", irn, bl, lvr_in, lvc_in);

                        if (lvr_end - lvc_end != 0)
                                ir_fprintf(stderr, "live end info for %+F at %+F differs: nml: %d, chk: %d\n", irn, bl, lvr_end, lvc_end);

                        if (lvr_out - lvc_out != 0)
                                ir_fprintf(stderr, "live out info for %+F at %+F differs: nml: %d, chk: %d\n", irn, bl, lvr_out, lvc_out);
                }
        }
        stat_ev_ctx_pop("be_lv_chk_compare");

        obstack_free(&obst, NULL);
}

BE_REGISTER_MODULE_CONSTRUCTOR(be_init_live)
void be_init_live(void)
{
        (void)be_live_chk_compare;
        FIRM_DBG_REGISTER(dbg, "firm.be.liveness");
}