[libfirm] / ir / be / bessadestr.c

/*
 * Copyright (C) 1995-2008 University of Karlsruhe.  All right reserved.
 *
 * This file is part of libFirm.
 *
 * This file may be distributed and/or modified under the terms of the
 * GNU General Public License version 2 as published by the Free Software
 * Foundation and appearing in the file LICENSE.GPL included in the
 * packaging of this file.
 *
 * Licensees holding valid libFirm Professional Edition licenses may use
 * this file in accordance with the libFirm Commercial License.
 * Agreement provided with the Software.
 *
 * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
 * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE.
 */

/**
 * @file
 * @brief       Performs SSA-Destruction.
 * @author      Daniel Grund
 * @date        25.05.2005
 */
#include "config.h"

#include "bessadestr.h"

#include "debug.h"
#include "set.h"
#include "pmap.h"
#include "irnode_t.h"
#include "ircons_t.h"
#include "iredges_t.h"
#include "irgwalk.h"
#include "irgmod.h"
#include "irdump.h"
#include "irprintf.h"

#include "be_t.h"
#include "beutil.h"
#include "bechordal_t.h"
#include "bearch.h"
#include "belive_t.h"
#include "benode.h"
#include "besched.h"
#include "bestatevent.h"
#include "beirg.h"
#include "beintlive_t.h"

DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)

static void clear_link(ir_node *irn, void *data)
{
        (void) data;
        set_irn_link(irn, NULL);
}

/**
 * For each block build a linked list of phis that
 *  - are in that block
 *  - have the current register class
 * The list is rooted at get_irn_link(BB).
 */
static void collect_phis_walker(ir_node *irn, void *data)
{
        be_chordal_env_t *env = (be_chordal_env_t*)data;
        if (is_Phi(irn) && chordal_has_class(env, irn)) {
                ir_node *bl = get_nodes_block(irn);
                set_irn_link(irn, get_irn_link(bl));
                set_irn_link(bl, irn);
        }
}

/**
 * This struct represents a Proj for a Perm.
 * It records the argument in the Perm and the corresponding Proj of the
 * Perm.
 */
typedef struct {
        ir_node *arg;  /**< The phi argument to make the Proj for. */
        int pos;       /**< The proj number the Proj will get.
                                                                         This also denotes the position of @p arg
                                                                         in the in array of the Perm. */
        ir_node *proj; /**< The proj created for @p arg. */
} perm_proj_t;

static int cmp_perm_proj(const void *a, const void *b, size_t n)
{
        const perm_proj_t *p = (const perm_proj_t*)a;
        const perm_proj_t *q = (const perm_proj_t*)b;
        (void) n;

        return !(p->arg == q->arg);
}

/**
 * Insert Perms in all predecessors of a block containing a phi
 */
static void insert_all_perms_walker(ir_node *bl, void *data)
{
        be_chordal_env_t *const chordal_env = (be_chordal_env_t*)data;
        be_lv_t *lv = be_get_irg_liveness(chordal_env->irg);
        int i, n;

        assert(is_Block(bl));

        /* If the link flag is NULL, this block has no phis. */
        if (!get_irn_link(bl))
                return;

        /* Look at all predecessors of the phi block */
        for (i = 0, n = get_irn_arity(bl); i < n; ++i) {
                ir_node *phi, *perm, *insert_after, **in;
                set *arg_set     = new_set(cmp_perm_proj, chordal_env->cls->n_regs);
                ir_node *pred_bl = get_Block_cfgpred_block(bl, i);
                int n_projs      = 0;

                /*
                 * Note that all phis in the list are in the same
                 * register class by construction.
                 */
                for (phi = (ir_node*)get_irn_link(bl); phi != NULL;
                     phi = (ir_node*)get_irn_link(phi)) {
                        ir_node                   *arg = get_irn_n(phi, i);
                        unsigned                   hash;
                        perm_proj_t                templ;

                        hash = hash_irn(arg);
                        templ.arg  = arg;
                        perm_proj_t *const pp = set_find(perm_proj_t, arg_set, &templ, sizeof(templ), hash);

                        /*
                         * If a proj_perm_t entry has not been made in the argument set,
                         * create one. The only restriction is, that the phi argument
                         * may not be live in at the current block, since this argument
                         * interferes with the phi and must thus not be member of a
                         * Perm. A copy will be inserted for this argument later on.
                         */
                        if (!pp && !be_is_live_in(lv, bl, arg)) {
                                templ.pos = n_projs++;
                                (void)set_insert(perm_proj_t, arg_set, &templ, sizeof(templ), hash);
                        }
                }


                if (n_projs) {
                        /*
                         * Create a new Perm with the arguments just collected
                         * above in the arg_set and insert it into the schedule.
                         */
                        in = XMALLOCN(ir_node*, n_projs);
                        foreach_set(arg_set, perm_proj_t, pp) {
                                in[pp->pos] = pp->arg;
                        }

                        perm = be_new_Perm(chordal_env->cls, pred_bl, n_projs, in);
                        be_stat_ev("phi_perm", n_projs);

                        insert_after = pred_bl;
                        do {
                                insert_after = sched_prev(insert_after);
                        } while (is_cfop(insert_after));
                        sched_add_after(insert_after, perm);

                        /*
                         * Make the Projs for the Perm and insert into schedule.
                         * Register allocation is copied from the former phi
                         * arguments to the projs (new phi arguments).
                         */
                        foreach_set(arg_set, perm_proj_t, pp) {
                                ir_node *proj = new_r_Proj(perm, get_irn_mode(pp->arg), pp->pos);
                                pp->proj = proj;
                                assert(arch_get_irn_register(pp->arg));
                                arch_set_irn_register(proj, arch_get_irn_register(pp->arg));
                                DBG((dbg, LEVEL_2, "Copy register assignment %s from %+F to %+F\n", arch_get_irn_register(pp->arg)->name, pp->arg, pp->proj));
                        }

                        /*
                         * Set the phi nodes to their new arguments: The Projs of the Perm
                         */
                        for (phi = (ir_node*)get_irn_link(bl); phi != NULL;
                             phi = (ir_node*)get_irn_link(phi)) {
                                perm_proj_t templ;

                                templ.arg = get_irn_n(phi, i);
                                perm_proj_t *const pp = set_find(perm_proj_t, arg_set, &templ, sizeof(templ), hash_irn(templ.arg));

                                /* If not found, it was an interfering argument */
                                if (pp) {
                                        set_irn_n(phi, i, pp->proj);
                                        be_liveness_introduce(lv, pp->proj);
                                }
                        }

                        /* update the liveness of the Perm's operands. It might be changed. */
                        {
                                int i;
                                for (i = 0; i < n_projs; ++i)
                                        be_liveness_update(lv, in[i]);
                        }
                        free(in);
                }

                del_set(arg_set);
        }
}

#define is_pinned(irn) (get_irn_link(irn))
#define get_pinning_block(irn) ((ir_node *)get_irn_link(irn))
#define pin_irn(irn, lock) (set_irn_link(irn, lock))

/**
 * Adjusts the register allocation for the (new) phi-operands
 * and insert duplicates iff necessary.
 */
static void set_regs_or_place_dupls_walker(ir_node *bl, void *data)
{
        be_chordal_env_t *chordal_env = (be_chordal_env_t*)data;
        be_lv_t *lv = be_get_irg_liveness(chordal_env->irg);
        ir_node *phi;

        /* Consider all phis of this block */
        for (phi = (ir_node*)get_irn_link(bl); phi != NULL;
             phi = (ir_node*)get_irn_link(phi)) {
                ir_node                     *phi_block = get_nodes_block(phi);
                const arch_register_t       *phi_reg   = arch_get_irn_register(phi);
                int                          max;
                int                          i;

                assert(is_Phi(phi) && "Can only handle phi-destruction :)");

                /* process all arguments of the phi */
                for (i = 0, max = get_irn_arity(phi); i < max; ++i) {
                        ir_node                   *arg = get_irn_n(phi, i);
                        const arch_register_t     *arg_reg;
                        ir_node                   *arg_block;

                        arg_block = get_Block_cfgpred_block(phi_block, i);
                        arg_reg   = arch_get_irn_register(arg);

                        assert(arg_reg && "Register must be set while placing perms");

                        DBG((dbg, LEVEL_1, "  for %+F(%s) -- %+F(%s)\n", phi, phi_reg->name, arg, arg_reg->name));

                        if (phi_reg == arg_reg
                                        || (arg_reg->type & arch_register_type_joker)
                                        || (arg_reg->type & arch_register_type_virtual)) {
                                /* Phi and arg have the same register, so pin and continue */
                                pin_irn(arg, phi_block);
                                DBG((dbg, LEVEL_1, "      arg has same reg: pin %+F(%s)\n", arg, arch_get_irn_register(arg)->name));
                                continue;
                        }

                        if (be_values_interfere(lv, phi, arg)) {
                                ir_node *schedpoint;

                                /*
                                        Insert a duplicate in arguments block,
                                        make it the new phi arg,
                                        set its register,
                                        insert it into schedule,
                                        pin it
                                */
                                ir_node *dupl = be_new_Copy(arg_block, arg);

                                set_irn_n(phi, i, dupl);
                                arch_set_irn_register(dupl, phi_reg);
                                schedpoint = arg_block;
                                do {
                                        schedpoint = sched_prev(schedpoint);
                                } while (is_cfop(schedpoint));
                                sched_add_after(schedpoint, dupl);
                                pin_irn(dupl, phi_block);
                                be_liveness_introduce(lv, dupl);
                                be_liveness_update(lv, arg);
                                DBG((dbg, LEVEL_1, "    they do interfere: insert %+F(%s)\n", dupl, arch_get_irn_register(dupl)->name));
                                continue; /* with next argument */
                        }

                        DBG((dbg, LEVEL_1, "    they do not interfere\n"));
                        assert(is_Proj(arg));
                        /*
                                First check if there is an other phi
                                - in the same block
                                - having arg at the current pos in its arg-list
                                - having the same color as arg

                                If found, then pin the arg (for that phi)
                        */
                        if (! is_pinned(arg)) {
                                ir_node *other_phi;

                                DBG((dbg, LEVEL_1, "      searching for phi with same arg having args register\n"));

                                for (other_phi = (ir_node*)get_irn_link(phi_block);
                                     other_phi != NULL;
                                     other_phi = (ir_node*)get_irn_link(other_phi)) {

                                        assert(is_Phi(other_phi)                               &&
                                                get_nodes_block(phi) == get_nodes_block(other_phi) &&
                                                "link fields are screwed up");

                                        if (get_irn_n(other_phi, i) == arg && arch_get_irn_register(other_phi) == arg_reg) {
                                                DBG((dbg, LEVEL_1, "        found %+F(%s)\n", other_phi, arch_get_irn_register(other_phi)->name));
                                                pin_irn(arg, phi_block);
                                                break;
                                        }
                                }
                        }

                        if (is_pinned(arg)) {
                                /*
                                        Insert a duplicate of the original value in arguments block,
                                        make it the new phi arg,
                                        set its register,
                                        insert it into schedule,
                                        pin it
                                */
                                ir_node *perm = get_Proj_pred(arg);
                                ir_node *dupl = be_new_Copy(arg_block, arg);
                                ir_node *ins;

                                set_irn_n(phi, i, dupl);
                                arch_set_irn_register(dupl, phi_reg);
                                /* skip the Perm's Projs and insert the copies behind. */
                                for (ins = sched_next(perm); is_Proj(ins); ins = sched_next(ins)) {
                                }
                                sched_add_before(ins, dupl);
                                pin_irn(dupl, phi_block);
                                be_liveness_introduce(lv, dupl);
                                be_liveness_update(lv, arg);
                                DBG((dbg, LEVEL_1, "      arg is pinned: insert %+F(%s)\n", dupl, arch_get_irn_register(dupl)->name));
                        } else {
                                /*
                                        No other phi has the same color (else arg would have been pinned),
                                        so just set the register and pin
                                */
                                arch_set_irn_register(arg, phi_reg);
                                pin_irn(arg, phi_block);
                                DBG((dbg, LEVEL_1, "      arg is not pinned: so pin %+F(%s)\n", arg, arch_get_irn_register(arg)->name));
                        }
                }
        }
}

void be_ssa_destruction(be_chordal_env_t *chordal_env)
{
        ir_graph *irg = chordal_env->irg;

        FIRM_DBG_REGISTER(dbg, "ir.be.ssadestr");

        be_invalidate_live_sets(irg);

        /* create a map for fast lookup of perms: block --> perm */
        irg_walk_graph(irg, clear_link, collect_phis_walker, chordal_env);

        DBG((dbg, LEVEL_1, "Placing perms...\n"));
        irg_block_walk_graph(irg, insert_all_perms_walker, NULL, chordal_env);

        if (chordal_env->opts->dump_flags & BE_CH_DUMP_SSADESTR)
                dump_ir_graph(irg, "ssa_destr_perms_placed");

        be_assure_live_chk(irg);

        DBG((dbg, LEVEL_1, "Setting regs and placing dupls...\n"));
        irg_block_walk_graph(irg, set_regs_or_place_dupls_walker, NULL, chordal_env);

        /* unfortunately updating doesn't work yet. */
        be_invalidate_live_chk(irg);

        if (chordal_env->opts->dump_flags & BE_CH_DUMP_SSADESTR)
                dump_ir_graph(irg, "ssa_destr_regs_set");
}

static void ssa_destruction_check_walker(ir_node *bl, void *data)
{
        ir_node *phi;
        int i, max;
        (void)data;

        for (phi = (ir_node*)get_irn_link(bl); phi != NULL;
             phi = (ir_node*)get_irn_link(phi)) {
                const arch_register_t *phi_reg, *arg_reg;

                phi_reg = arch_get_irn_register(phi);
                /* iterate over all args of phi */
                for (i = 0, max = get_irn_arity(phi); i < max; ++i) {
                        ir_node                   *arg = get_irn_n(phi, i);
                        const arch_register_req_t *req = arch_get_irn_register_req(arg);

                        if (req->type & arch_register_req_type_ignore)
                                continue;

                        arg_reg = arch_get_irn_register(arg);

                        if (phi_reg != arg_reg) {
                                DBG((dbg, 0, "Error: Registers of %+F and %+F differ: %s %s\n", phi, arg, phi_reg->name, arg_reg->name));
                                assert(0);
                        }

                        if (! is_pinned(arg)) {
                                DBG((dbg, 0, "Warning: Phi argument %+F is not pinned.\n", arg));
                                assert(0);
                        }
                }
        }
}

void be_ssa_destruction_check(be_chordal_env_t *chordal_env)
{
        irg_block_walk_graph(chordal_env->irg, ssa_destruction_check_walker, NULL, NULL);
}