[libfirm] / ir / be / bessadestr.c

/**
 * Author:      Daniel Grund
 * Date:                25.05.2005
 * Copyright:   (c) Universitaet Karlsruhe
 * Licence:     This file protected by GPL -  GNU GENERAL PUBLIC LICENSE.
 *
 * Performs SSA-Destruction.
 */
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#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_t.h"
#include "besched_t.h"

static firm_dbg_module_t *dbg = NULL;
#define DUMP_GRAPHS

#define get_chordal_arch(ce) ((ce)->birg->main_env->arch_env)
#define get_reg(irn) arch_get_irn_register(get_chordal_arch(chordal_env), irn)
#define set_reg(irn, reg) arch_set_irn_register(get_chordal_arch(chordal_env), irn, reg)

#define is_Perm(irn)            (arch_irn_classify(arch_env, irn) == arch_irn_class_perm)
#define get_reg_cls(irn)        (arch_get_irn_reg_class(arch_env, irn, -1))
#define is_curr_reg_class(irn)  (get_reg_cls(p) == chordal_env->cls)

static void clear_link(ir_node *irn, 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 = 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 = a;
        const perm_proj_t *q = b;
        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 *chordal_env = data;
        pmap *perm_map = chordal_env->data;
        ir_graph *irg = 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;
                perm_proj_t *pp;
                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;

                assert(!pmap_contains(perm_map, pred_bl) && "Already permed that block");

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

                        templ.arg  = arg;
                        pp         = set_find(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 alter on.
                         */
                        if(!pp && !is_live_in(bl, arg)) {
                                templ.pos = n_projs++;
                                set_insert(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 = xmalloc(n_projs * sizeof(in[0]));
                        for(pp = set_first(arg_set); pp; pp = set_next(arg_set))
                                in[pp->pos] = pp->arg;

                        perm = be_new_Perm(chordal_env->cls, irg, pred_bl, n_projs, in);
                        free(in);
                        insert_after = sched_skip(sched_last(pred_bl), 0, sched_skip_cf_predicator, chordal_env->birg->main_env->arch_env);
                        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).
                         */
                        insert_after = perm;
                        for(pp = set_first(arg_set); pp; pp = set_next(arg_set)) {
                                ir_node *proj = new_r_Proj(irg, pred_bl, perm, get_irn_mode(pp->arg), pp->pos);
                                pp->proj = proj;
                                assert(get_reg(pp->arg));
                                set_reg(proj, get_reg(pp->arg));
                                sched_add_after(insert_after, proj);
                                insert_after = proj;
                                DBG((dbg, LEVEL_2, "Copy register assignment %s from %+F to %+F\n", get_reg(pp->arg)->name, pp->arg, pp->proj));
                        }

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

                                templ.arg = get_irn_n(phi, i);
                                pp        = set_find(arg_set, &templ, sizeof(templ), HASH_PTR(templ.arg));

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

                        /* register in perm map */
                        pmap_insert(perm_map, pred_bl, perm);
                }

                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 = data;
        ir_node *phi;

        /* Consider all phis of this block */
        for(phi = get_irn_link(bl); phi; phi = get_irn_link(phi)) {
                int i, max;
                ir_node *arg, *phi_block, *arg_block;
                const arch_register_t *phi_reg, *arg_reg;
                const arch_register_class_t *cls;

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

                phi_block = get_nodes_block(phi);
                phi_reg = get_reg(phi);
                cls = arch_get_irn_reg_class(get_chordal_arch(chordal_env), phi, -1);

                /* process all arguments of the phi */
                for(i=0, max=get_irn_arity(phi); i<max; ++i) {
                        arg = get_irn_n(phi, i);
                        arg_block = get_Block_cfgpred_block(phi_block, i);
                        arg_reg = get_reg(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(nodes_interfere(chordal_env, phi, arg)) {
                                /* 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(cls, chordal_env->irg, arg_block, arg);
                                assert(get_irn_mode(phi) == get_irn_mode(dupl));
                                set_irn_n(phi, i, dupl);
                                set_reg(dupl, phi_reg);
                                sched_add_after(sched_skip(sched_last(arg_block), 0, sched_skip_cf_predicator, chordal_env->birg->main_env->arch_env), dupl);
                                pin_irn(dupl, phi_block);
                                DBG((dbg, LEVEL_1, "    they do interfere: insert %+F(%s)\n", dupl, get_reg(dupl)->name));
                                continue; /* with next argument */
                        }

                        if (phi_reg == arg_reg) {
                                /* 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, get_reg(arg)->name));
                                continue;
                        }

                        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 = get_irn_link(phi_block); other_phi; other_phi = 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 && get_reg(other_phi) == arg_reg) {
                                                DBG((dbg, LEVEL_1, "        found %+F(%s)\n", other_phi, get_reg(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 *orig_val = get_irn_n(perm, get_Proj_proj(arg));
                                ir_node *dupl = be_new_Copy(cls, chordal_env->irg, arg_block, orig_val);
                                assert(get_irn_mode(phi) == get_irn_mode(dupl));
                                set_irn_n(phi, i, dupl);
                                set_reg(dupl, phi_reg);
                                sched_add_before(perm, dupl);
                                pin_irn(dupl, phi_block);
                                DBG((dbg, LEVEL_1, "      arg is pinned: insert %+F(%s)\n", dupl, get_reg(dupl)->name));
                        } else {
                                /* No other phi has the same color (else arg would have been pinned),
                                 * so just set the register and pin
                                 */
                                set_reg(arg, phi_reg);
                                pin_irn(arg, phi_block);
                                DBG((dbg, LEVEL_1, "      arg is not pinned: so pin %+F(%s)\n", arg, get_reg(arg)->name));
                        }
                }
        }
}

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

        dbg = firm_dbg_register("ir.be.ssadestr");

        /* create a map for fast lookup of perms: block --> perm */
        chordal_env->data = perm_map;
        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);
#ifdef DUMP_GRAPHS
        be_dump(irg, "-ssa_destr_perms_placed", dump_ir_block_graph_sched);
#endif

        be_liveness(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);
#ifdef DUMP_GRAPHS
        be_dump(irg, "-ssa_destr_regs_set", dump_ir_block_graph_sched);
#endif

        pmap_destroy(perm_map);
}

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

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

                phi_reg = get_reg(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);
                        arg_reg = get_reg(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, chordal_env);
}