[libfirm] / ir / ir / irgopt.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    Optimizations for a whole ir graph, i.e., a procedure.
 * @author   Christian Schaefer, Goetz Lindenmaier, Sebastian Felis,
 *           Michael Beck
 * @version  $Id$
 */
#include "config.h"

#include <assert.h>

#include "irnode_t.h"
#include "irgraph_t.h"

#include "iroptimize.h"
#include "iropt_t.h"
#include "irgopt.h"
#include "irgmod.h"
#include "irgwalk.h"

#include "adt/pdeq.h"

#include "irpass_t.h"
#include "irflag_t.h"
#include "iredges_t.h"
#include "irtools.h"

/*------------------------------------------------------------------*/
/* apply optimizations of iropt to all nodes.                       */
/*------------------------------------------------------------------*/

/**
 * A wrapper around optimize_inplace_2() to be called from a walker.
 */
static void optimize_in_place_wrapper(ir_node *n, void *env)
{
        ir_node *optimized = optimize_in_place_2(n);
        (void) env;

        if (optimized != n) {
                exchange(n, optimized);
        }
}

/**
 * Do local optimizations for a node.
 *
 * @param n  the IR-node where to start. Typically the End node
 *           of a graph
 *
 * @note current_ir_graph must be set
 */
static inline void do_local_optimize(ir_node *n)
{
        ir_graph *irg = get_irn_irg(n);

        /* Handle graph state */
        assert(get_irg_phase_state(irg) != phase_building);

        if (get_opt_global_cse())
                set_irg_pinned(irg, op_pin_state_floats);
        set_irg_outs_inconsistent(irg);
        set_irg_doms_inconsistent(irg);
        set_irg_loopinfo_inconsistent(irg);

        /* Clean the value_table in irg for the CSE. */
        new_identities(irg);

        /* walk over the graph */
        irg_walk(n, firm_clear_link, optimize_in_place_wrapper, NULL);
}

/* Applies local optimizations (see iropt.h) to all nodes reachable from node n */
void local_optimize_node(ir_node *n)
{
        ir_graph *rem = current_ir_graph;
        current_ir_graph = get_irn_irg(n);

        do_local_optimize(n);

        current_ir_graph = rem;
}

/**
 * Block-Walker: uses dominance depth to mark dead blocks.
 */
static void kill_dead_blocks(ir_node *block, void *env)
{
        (void) env;

        if (get_Block_dom_depth(block) < 0) {
                /*
                 * Note that the new dominance code correctly handles
                 * the End block, i.e. it is always reachable from Start
                 */
                ir_graph *irg = get_irn_irg(block);
                exchange(block, get_irg_bad(irg));
        }
}

/* Applies local optimizations (see iropt.h) to all nodes reachable from node n. */
void local_optimize_graph(ir_graph *irg)
{
        ir_graph *rem = current_ir_graph;
        current_ir_graph = irg;

        do_local_optimize(get_irg_end(irg));

        current_ir_graph = rem;
}

/**
 * Enqueue all users of a node to a wait queue.
 * Handles mode_T nodes.
 */
static void enqueue_users(ir_node *n, pdeq *waitq)
{
        const ir_edge_t *edge;

        foreach_out_edge(n, edge) {
                ir_node *succ = get_edge_src_irn(edge);

                if (get_irn_link(succ) != waitq) {
                        pdeq_putr(waitq, succ);
                        set_irn_link(succ, waitq);
                }
                if (get_irn_mode(succ) == mode_T) {
                /* A mode_T node has Proj's. Because most optimizations
                        run on the Proj's we have to enqueue them also. */
                        enqueue_users(succ, waitq);
                }
        }
}

/**
 * Data flow optimization walker.
 * Optimizes all nodes and enqueue its users
 * if done.
 */
static void opt_walker(ir_node *n, void *env)
{
        pdeq *waitq = (pdeq*)env;
        ir_node *optimized;

        optimized = optimize_in_place_2(n);
        set_irn_link(optimized, NULL);

        if (optimized != n) {
                enqueue_users(n, waitq);
                exchange(n, optimized);
        }
}

/* Applies local optimizations to all nodes in the graph until fixpoint. */
int optimize_graph_df(ir_graph *irg)
{
        pdeq     *waitq = new_pdeq();
        ir_graph *rem = current_ir_graph;
        ir_node  *end;
        int      state, changed;

        current_ir_graph = irg;

        state = edges_assure(irg);

        /* Clean the value_table in irg for the CSE. */
        new_identities(irg);

        if (get_opt_global_cse()) {
                set_irg_pinned(irg, op_pin_state_floats);
        } else {
                /* The following enables unreachable code elimination (=Blocks may be
                 * Bad). We cannot enable it in global_cse nodes since we can't
                 * determine a nodes block there and therefore can't remove all code
                 * in unreachable blocks */
                set_irg_state(irg, IR_GRAPH_STATE_BAD_BLOCK);
                if (get_irg_dom_state(irg) == dom_consistent)
                        irg_block_walk_graph(irg, NULL, kill_dead_blocks, NULL);
        }

        /* invalidate info */
        set_irg_outs_inconsistent(irg);
        set_irg_doms_inconsistent(irg);
        set_irg_loopinfo_inconsistent(irg);

        ir_reserve_resources(irg, IR_RESOURCE_IRN_LINK);

        /* walk over the graph, but don't touch keep-alives */
        irg_walk_graph(irg, NULL, opt_walker, waitq);

        /* any optimized nodes are stored in the wait queue,
         * so if it's not empty, the graph has been changed */
        changed = !pdeq_empty(waitq);

        /* finish the wait queue */
        while (! pdeq_empty(waitq)) {
                ir_node *n = (ir_node*)pdeq_getl(waitq);
                if (! is_Bad(n))
                        opt_walker(n, waitq);
        }

        del_pdeq(waitq);

        ir_free_resources(irg, IR_RESOURCE_IRN_LINK);

        if (! state)
                edges_deactivate(irg);

        /* Finally kill BAD and doublets from the keep alives.
           Doing this AFTER edges where deactivated saves cycles */
        end  = get_irg_end(irg);
        remove_End_Bads_and_doublets(end);

        clear_irg_state(irg, IR_GRAPH_STATE_BAD_BLOCK);

        current_ir_graph = rem;
        return changed;
}

/* Creates an ir_graph pass for optimize_graph_df. */
ir_graph_pass_t *optimize_graph_df_pass(const char *name)
{
        return def_graph_pass_ret(name ? name : "optimize_graph_df", optimize_graph_df);
}  /* optimize_graph_df_pass */