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[libfirm] / ir / be / beraextern.c

/**
 * Author:      Daniel Grund
 * Date:                17.01.2006
 * Copyright:   (c) Universitaet Karlsruhe
 * Licence:     This file protected by GPL -  GNU GENERAL PUBLIC LICENSE.
 *
 * Implementation of the RA-Interface for an external, (non-SSA) register allocator.
 *
 * The external register allocator is a program:
 *    PROG -i INPUTFILE -o OUTPUTFILE
 *
 *   1) Input file defines the interference graph
 *   2) Output file contains the instructions to perform
 *


The input file format
----------------------

inputfile       ::= regs nodes interf affinities .

regs            ::= 'regs' regcount .                                           // Anzahl der register (0..regcount-1), die zur Verfuegung stehen

nodes           ::= 'nodes' '{' node* '}' .                                     // All nodes in the graph

node            ::= node-info
                          | node-info '<' reg-nr '>' .                          // Reg-nr is present in case of constraints

node-info       ::= node-nr spill-costs .

interf          ::= 'interferences' '{' edge* '}' .                     // Interference edges of the graph

affinities      ::= 'affinities' '{' edge* '}' .                        // Affinity edges of the graph

edge            ::= '(' node-nr ',' node-nr ')' .


spill-costs, regcount, node-nr ::= integer .


The output file format
-----------------------

outputfile      ::= spills | allocs .

spills          ::= 'spills' node-nr+ .

allocs          ::= 'allocs' alloc* .

alloc           ::= node-nr reg-nr .


******** End of file format docu ********/

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#ifdef WIN32
#include <malloc.h>
#else
#include <alloca.h>
#endif

#include <stdio.h>
#include <stdlib.h>
#ifdef WITH_LIBCORE
#include <libcore/lc_opts.h>
#include <libcore/lc_opts_enum.h>
#endif

#include "set.h"
#include "pset.h"
#include "pmap.h"
#include "bitset.h"

#include "irprintf_t.h"
#include "irnode_t.h"
#include "irgraph_t.h"
#include "irgwalk.h"
#include "iredges_t.h"
#include "irdom_t.h"
#include "phiclass.h"

#include "beraextern.h"
#include "bearch.h"
#include "benode_t.h"
#include "beirgmod.h"
#include "besched.h"
#include "beutil.h"

typedef struct _var_info_t var_info_t;

/**
 * Environment with all the needed stuff
 */
typedef struct _be_raext_env_t {
        arch_env_t *aenv;
        const arch_register_class_t *cls;
        ir_graph *irg;
        dom_front_info_t *dom_info;

        FILE *f;                                /**< file handle used for out- and input file */
        set *vars;                              /**< contains all var_info_t */
        int n_cls_vars;                 /**< length of the array cls_vars */
        var_info_t **cls_vars;  /**< only the var_infos for current cls. needed for double iterating */
} be_raext_env_t;



/******************************************************************************
    _    _      _
   | |  | |    | |
   | |__| | ___| |_ __   ___ _ __ ___
   |  __  |/ _ \ | '_ \ / _ \ '__/ __|
   | |  | |  __/ | |_) |  __/ |  \__ \
   |_|  |_|\___|_| .__/ \___|_|  |___/
                 | |
                 |_|
 *****************************************************************************/


#define pset_foreach(pset, irn)  for(irn=pset_first(pset); irn; irn=pset_next(pset))
#define set_foreach(set, e)  for(e=set_first(set); e; e=set_next(set))

/**
 * Checks if _the_ result of the irn belongs to the
 * current register class (raenv->cls)
 * NOTE: Only the first result is checked.
 */
#define is_res_in_reg_class(irn) arch_irn_has_reg_class(raenv->aenv, irn, -1, raenv->cls)

static INLINE ir_node *get_first_non_phi(pset *s) {
        ir_node *irn;

        pset_foreach(s, irn)
                if (!is_Phi(irn)) {
                        pset_break(s);
                        return irn;
                }

        assert(0 && "There must be a non-phi-irn in this");
        return NULL;
}

static INLINE ir_node *get_first_phi(pset *s) {
        ir_node *irn;

        pset_foreach(s, irn)
                if (is_Phi(irn)) {
                        pset_break(s);
                        return irn;
                }

        assert(0 && "There must be a phi in this");
        return NULL;
}

/******************************************************************************
    _____                _            _____            _
   / ____|              | |          / ____|          (_)
  | |     ___  _ __  ___| |_ _ __   | |     ___  _ __  _  ___  ___
  | |    / _ \| '_ \/ __| __| '__|  | |    / _ \| '_ \| |/ _ \/ __|
  | |___| (_) | | | \__ \ |_| |     | |___| (_) | |_) | |  __/\__ \
   \_____\___/|_| |_|___/\__|_|      \_____\___/| .__/|_|\___||___/
                                                | |
                                                |_|
 *****************************************************************************/

static void handle_constraints_walker(ir_node *irn, void *env) {
        be_raext_env_t *raenv = env;
        arch_register_req_t req;
        int pos, max;

        /* handle output constraints
         * user -> irn    becomes    user -> cpy -> irn
         */
        arch_get_register_req(raenv->aenv, &req, irn, -1);
        if (arch_register_req_is(&req, limited)) {
                ir_node *cpy = be_new_Copy(req.cls, raenv->irg, get_nodes_block(irn), irn);
                const ir_edge_t *edge;

                /* all users of the irn use the copy instead */
                sched_add_after(irn, cpy);
                foreach_out_edge(irn, edge)
                        set_irn_n(edge->src, edge->pos, cpy);
        }


        /* handle input constraints by converting them into output constraints
         * of copies of the former argument
         * irn -> arg   becomes  irn -> copy -> arg
     */
        for (pos = 0, max = get_irn_arity(irn); pos<max; ++pos) {
                arch_get_register_req(raenv->aenv, &req, irn, pos);
                if (arch_register_req_is(&req, limited)) {
                        ir_node *arg = get_irn_n(irn, pos);
                        ir_node *cpy = be_new_Copy(req.cls, raenv->irg, get_nodes_block(irn), arg);

                        /* use the copy instead */
                        sched_add_before(irn, cpy);
                        set_irn_n(irn, pos, cpy);

                        /* set an out constraint for the copy */
                        be_set_constr_limited(cpy, -1, &req);
                }
        }
}

static void handle_constraints(be_raext_env_t *raenv) {
        irg_block_walk_graph(raenv->irg, NULL, handle_constraints_walker, raenv);
}


/******************************************************************************
     _____ _____              _____            _
    / ____/ ____|  /\        |  __ \          | |
   | (___| (___   /  \ ______| |  | | ___  ___| |_ _ __
    \___ \\___ \ / /\ \______| |  | |/ _ \/ __| __| '__|
    ____) |___) / ____ \     | |__| |  __/\__ \ |_| |
   |_____/_____/_/    \_\    |_____/ \___||___/\__|_|

 *****************************************************************************/

#define mark_as_done(irn, pos)                  set_irn_link(irn, INT_TO_PTR(pos+1))
#define has_been_done(irn, pos)                 (PTR_TO_INT(get_irn_link(irn)) > pos)

/**
 * Insert a copy for the argument of @p start_phi found at position @p pos.
 * Also searches a phi-loop of arbitrary length to detect and resolve
 *   the class of phi-swap-problems. To search for a loop recursion is used.
 *
 * 1) Simplest case (phi with a non-phi arg):
 *     A single copy is inserted.
 *
 * 2) Phi chain (phi (with phi-arg)* with non=phi arg):
 *     Several copies are placed, each after returning from recursion.
 *
 * 3) Phi-loop:
 *     On detection a loop breaker is inserted, which is a copy of the start_phi.
 *     This copy then pretends beeing the argumnent of the last phi.
 *     Now case 2) can be used.
 *
 * The values of @p start_phi and @p pos never change during recursion.
 *
 * @p raenv      Environment with all the stuff needed
 * @p start_phi  Phi node to process
 * @p pos        Argument position to insert copy/copies for
 * @p curr_phi   Phi node currently processed during recursion. Equals start_phi on initial call
 *
 * @return NULL  If no copy is necessary
 *         NULL  If the phi has already been processed at this pos
 *               Link field is used to keep track of processed positions
 *         In all other cases the ir_node *copy which was placed is returned.
 */
static ir_node *insert_copies(be_raext_env_t *raenv, ir_node *start_phi, int pos, ir_node *curr_phi) {
        ir_node *arg = get_irn_n(curr_phi, pos);
        ir_node *arg_blk = get_nodes_block(arg);
        ir_node *pred_blk = get_Block_cfgpred_block(get_nodes_block(curr_phi), pos);
        ir_node *curr_cpy, *last_cpy;

        assert(is_Phi(start_phi) && is_Phi(curr_phi));

        if (has_been_done(start_phi, pos))
                return NULL;

        /* In case this is a 'normal' phi we insert into
         * the schedule before the pred_blk irn */
        last_cpy = pred_blk;

        /* If we detect a loop stop recursion. */
        if (arg == start_phi) {
                ir_node *loop_breaker;
                if (start_phi == curr_phi) {
                        /* Phi directly uses itself. No copy necessary */
                        return NULL;
                }

                /* At least 2 phis are involved */
                /* Insert a loop breaking copy (an additional variable T) */
                loop_breaker = be_new_Copy(raenv->cls, raenv->irg, pred_blk, start_phi);
                sched_add_before(pred_blk, loop_breaker);

                arg = loop_breaker;
        }

        /* If arg is a phi in the same block we have to continue search */
        if (is_Phi(arg) && arg_blk == get_nodes_block(start_phi))
                last_cpy = insert_copies(raenv, start_phi, pos, arg);

        /* Insert copy of argument (may be the loop-breaker) */
        curr_cpy = be_new_Copy(raenv->cls, raenv->irg, pred_blk, arg);
        set_irn_n(curr_phi, pos, curr_cpy);
        mark_as_done(curr_phi, pos);
        sched_add_before(last_cpy, curr_cpy);
        return curr_cpy;
}


/**
 * Perform simple SSA-destruction with copies.
 * The order of processing _must_ be
 *  for all positions {
 *    for all phis {
 *      doit
 *    }
 *  }
 * else the magic to keep track of processed phi-positions will fail in
 * function 'insert_copies'
 */
static void ssa_destr_simple_walker(ir_node *blk, void *env) {
        be_raext_env_t *raenv = env;
        int pos, max;
        ir_node *phi;

        /* for all argument positions of the phis */
        for (pos=0, max=get_irn_arity(blk); pos<max; ++pos) {

                /* for all phi nodes (which are scheduled first) */
                sched_foreach(blk, phi) {
                        if (!is_Phi(phi))
                                break;

                        raenv->cls = arch_get_irn_reg_class(raenv->aenv, phi, -1);
                        insert_copies(raenv, phi, pos, phi);
                }
        }
}


static void ssa_destr_simple(be_raext_env_t *raenv) {
        be_clear_links(raenv->irg);
        irg_block_walk_graph(raenv->irg, ssa_destr_simple_walker, NULL, raenv);
}


static void ssa_destr_rastello(be_raext_env_t *raenv) {
        assert(0 && "NYI");
        exit(0xDeadBeef);
        /*
        phi_class_compute(raenv->irg);
        irg_block_walk_graph(irg, ssa_destr_rastello, NULL, &raenv);
        */
}

/******************************************************************************
   __      __   _       ___   __      __
   \ \    / /  | |     |__ \  \ \    / /
    \ \  / /_ _| |___     ) |  \ \  / /_ _ _ __ ___
     \ \/ / _` | / __|   / /    \ \/ / _` | '__/ __|
      \  / (_| | \__ \  / /_     \  / (_| | |  \__ \
       \/ \__,_|_|___/ |____|     \/ \__,_|_|  |___/
 *****************************************************************************/

/**
 * This struct maps a variable (nr) to the values belonging to this variable
 */
struct _var_info_t {
        int var_nr;             /* the key */
        pset *values;   /* the ssa-values belonging to this variable */
};

#define SET_REMOVED -1

/**
 * The link field of an irn points to the var_info struct
 * representing the corresponding variable.
 */
#define set_var_info(irn, vi)                           set_irn_link(irn, vi)
#define get_var_info(irn)                                       ((var_info_t *)get_irn_link(irn))

#define HASH_VAR_NR(var_nr) var_nr

static int compare_var_infos(const void *e1, const void *e2, size_t size) {
        const var_info_t *v1 = e1;
        const var_info_t *v2 = e2;

        if (v1->var_nr == SET_REMOVED || v2->var_nr == SET_REMOVED)
                return 1;

        return v1->var_nr != v2->var_nr;
}

static INLINE var_info_t *var_find(set *vars, int var_nr) {
        var_info_t vi;
        vi.var_nr = var_nr;

        return set_find(vars, &vi, sizeof(vi), HASH_VAR_NR(var_nr));
}

static INLINE var_info_t *var_find_or_insert(set *vars, int var_nr) {
        var_info_t vi, *found;
        memset(&vi, 0, sizeof(vi));
        vi.var_nr = var_nr;

        found = set_insert(vars, &vi, sizeof(vi), HASH_VAR_NR(var_nr));

        if (!found->values)
                found->values  = pset_new_ptr(1);

        return found;
}

/**
 * Adds a value to a variable. Sets all pointers accordingly.
 */
static INLINE var_info_t *var_add_value(be_raext_env_t *raenv, int var_nr, ir_node *irn) {
        var_info_t *vi = var_find_or_insert(raenv->vars, var_nr);

        /* var 2 value mapping */
        pset_insert_ptr(vi->values, irn);

        /* value 2 var mapping */
        set_var_info(irn, vi);

        return vi;
}

static INLINE pset *get_var_values(be_raext_env_t *raenv, int var_nr) {
        var_info_t *vi = var_find(raenv->vars, var_nr);
        assert(vi && "Variable does not exist");
        return vi->values;
}

/**
 * Define variables (numbers) for all SSA-values.
 * All values in a phi class get assigned the same variable name.
 * The link field maps values to the var-name
 */
static void values_to_vars(ir_node *irn, void *env) {
        be_raext_env_t *raenv = env;
        int nr;
        pset *vals;

        vals = get_phi_class(irn);

        if (vals) {
                nr = get_irn_node_nr(get_first_phi(vals));
        } else {
                /* not a phi class member, value == var */
                nr = get_irn_node_nr(irn);
                vals = pset_new_ptr(1);
                pset_insert_ptr(vals, irn);
        }

        /* values <--> var mapping */
        pset_foreach(vals, irn)
                var_add_value(raenv, nr, irn);
}


/******************************************************************************
    _____
   |  __ \
   | |  | |_   _ _ __ ___  _ __   ___ _ __
   | |  | | | | | '_ ` _ \| '_ \ / _ \ '__|
   | |__| | |_| | | | | | | |_) |  __/ |
   |_____/ \__,_|_| |_| |_| .__/ \___|_|
                          | |
                          |_|
 *****************************************************************************/


static void extract_vars_of_cls(be_raext_env_t *raenv) {
        int count = 0;
        var_info_t *vi;

        raenv->cls_vars = malloc(set_count(raenv->vars) * sizeof(*raenv->cls_vars));
        assert(raenv->cls_vars);

        set_foreach(raenv->vars, vi)
                if (is_res_in_reg_class(get_first_non_phi(vi->values)))
                        raenv->cls_vars[count++] = vi;

        raenv->cls_vars = realloc(raenv->cls_vars, count * sizeof(*raenv->cls_vars));
        assert(raenv->cls_vars);

        raenv->n_cls_vars = count;
}


/**
 * Check if node irn has a limited-constraint at position pos.
 * If yes, dump it to FILE raenv->f
 */
static INLINE void dump_constraint(be_raext_env_t *raenv, ir_node *irn, int pos) {
        bitset_t *bs = bitset_alloca(raenv->cls->n_regs);
        arch_register_req_t req;

        arch_get_register_req(raenv->aenv, &req, irn, pos);
        if (arch_register_req_is(&req, limited)) {
                int reg_nr;
                req.limited(req.limited_env, bs);
                reg_nr = bitset_next_set(bs, 0);
                fprintf(raenv->f, "<%d>", reg_nr);
                assert(-1 == bitset_next_set(bs, reg_nr+1) && "Constraints with more than 1 possible register are not supported");
        }
}

static INLINE int get_spill_costs(var_info_t *vi) {
        ir_node *irn;
        int n_spills=0, n_reloads=0;

        pset_foreach(vi->values, irn) {
                if (is_Phi(irn)) {
                        /* number of reloads is the number of non-phi uses of all values of this var */
                        const ir_edge_t *edge;
                        foreach_out_edge(irn, edge)
                                if (!is_Phi(edge->src))
                                        n_reloads++;
                } else {
                        /* number of spills is the number of non-phi values for this var */
                        n_spills++;
                }
        }

        return n_spills + n_reloads;
}

static void dump_nodes(be_raext_env_t *raenv) {
        FILE *f = raenv->f;
        int i;

        fprintf(f, "\nnodes {\n");

        for (i=0; i<raenv->n_cls_vars; ++i) {
                var_info_t *vi = raenv->cls_vars[i];

                if (vi->var_nr == SET_REMOVED)
                        continue;

                fprintf(f, "%d %d", vi->var_nr, get_spill_costs(vi));
                dump_constraint(raenv, get_first_non_phi(vi->values), -1);
                fprintf(f, "\n");
        }

        fprintf(f, "}\n");
}


static void dump_interferences(be_raext_env_t *raenv) {
        int i,o;
        var_info_t *vi1, *vi2;
        ir_node *irn1, *irn2;
        FILE *f = raenv->f;

        fprintf(f, "\ninterferences {\n");

        for (i=0; i<raenv->n_cls_vars; ++i) {
                vi1 = raenv->cls_vars[i];

                if (vi1->var_nr == SET_REMOVED)
                        continue;

                for (o=i+1; o<raenv->n_cls_vars; ++o) {
                        vi2 = raenv->cls_vars[o];

                        if (vi2->var_nr == SET_REMOVED)
                                continue;

                        pset_foreach(vi1->values, irn1)
                                pset_foreach(vi2->values, irn2)
                                        if (values_interfere(irn1, irn2)) {
                                                pset_break(vi1->values);
                                                pset_break(vi2->values);
                                                fprintf(f, "(%d, %d)\n", vi1->var_nr, vi2->var_nr);
                                        }
                }
        }
        fprintf(f, "}\n");
}


static void dump_affinities_walker(ir_node *irn, void *env) {
        be_raext_env_t *raenv = env;
        arch_register_req_t req;
        int pos, max;
        var_info_t *vi1, *vi2;

        vi1 = get_var_info(irn);

        /* copies have affinities */
        /* TODO? remove this case by adding should_be_equal requirements */
        if (arch_irn_classify(raenv->aenv, irn) == arch_irn_class_copy) {
                vi2 = get_var_info(get_irn_n(irn, 0));

                fprintf(raenv->f, "(%d, %d)\n",  vi1->var_nr, vi2->var_nr);
        }


        /* should_be_equal constraints are affinites */
        for (pos = 0, max = get_irn_arity(irn); pos<max; ++pos) {
                arch_get_register_req(raenv->aenv, &req, irn, pos);

                if (arch_register_req_is(&req, should_be_same)) {
                        vi2 = get_var_info(req.other_same);

                        fprintf(raenv->f, "(%d, %d)\n",  vi1->var_nr, vi2->var_nr);
                }
        }
}


static void dump_affinities(be_raext_env_t *raenv) {
        fprintf(raenv->f, "\ninterferences {\n");
        irg_walk_graph(raenv->irg, NULL, dump_affinities_walker, raenv);
        fprintf(raenv->f, "}\n");
}

/**
 * Dump all information needed by the external
 * register allocator to a single file.
 */
static void dump_to_file(be_raext_env_t *raenv, char *filename) {
        FILE *f;

        if (!(f = fopen(filename, "wt"))) {
                fprintf(stderr, "Could not open file %s for writing\n", filename);
                exit(0xdeadbeef);
        }
        raenv->f = f;

        /* dump register info */
        fprintf(f, "regs %d\n", arch_register_class_n_regs(raenv->cls));

        /* dump the interference graph */
        dump_nodes(raenv);
        dump_interferences(raenv);
        dump_affinities(raenv);

        fclose(f);
}

/******************************************************************************
    ______                     _
   |  ____|                   | |
   | |__  __  _____  ___ _   _| |_ ___
   |  __| \ \/ / _ \/ __| | | | __/ _ \
   | |____ >  <  __/ (__| |_| | ||  __/
   |______/_/\_\___|\___|\__,_|\__\___|
 *****************************************************************************/

/**
 * Execute the external register allocator specified in the
 * firm-option firm.be.ra.ext.callee
 */
static void execute(char *prog_to_call, char *out_file, char *result_file) {
        char cmd_line[1024];
        int ret_status;

        snprintf(cmd_line, sizeof(cmd_line), "%s -i %s -o %s", prog_to_call, out_file, result_file);

        ret_status = system(cmd_line);
        assert(ret_status != -1 && "Invokation of external register allocator failed");
}

/******************************************************************************
                         _         _____                 _ _
       /\               | |       |  __ \               | | |
      /  \   _ __  _ __ | |_   _  | |__) |___  ___ _   _| | |_
     / /\ \ | '_ \| '_ \| | | | | |  _  // _ \/ __| | | | | __|
    / ____ \| |_) | |_) | | |_| | | | \ \  __/\__ \ |_| | | |_
   /_/    \_\ .__/| .__/|_|\__, | |_|  \_\___||___/\__,_|_|\__|
            | |   | |       __/ |
            |_|   |_|      |___/
 *****************************************************************************/

/**
 * Spill a variable and add reloads before all uses.
 */
static INLINE void var_add_spills_and_reloads(be_raext_env_t *raenv, int var_nr) {
        var_info_t *vi = var_find(raenv->vars, var_nr);
        ir_node *spill=NULL, *ctx, *irn;
        const ir_edge_t *edge;
        pset *spills  = pset_new_ptr(4);        /* the spills of this variable */
        pset *reloads = pset_new_ptr(4);        /* the reloads of this variable */
        int new_size, n_spills, n_reloads;

        assert(vi && "Variable nr does not exist!");
        assert(pset_count(vi->values) && "There are no values associated to this variable");

        /* the spill context is set to an arbitrary node of the phi-class */
        ctx = get_first_phi(vi->values);

        /* for each value of this variable insert the spills */
        pset_foreach(vi->values, irn) {
                if (is_Phi(irn))
                        continue;

                /* all ordinary nodes must be spilled */
                spill = be_new_Spill(raenv->cls, raenv->irg, get_nodes_block(irn), irn, ctx);
                sched_add_after(irn, spill);

                /* remember the spill */
                pset_insert_ptr(spills, spill);
        }

        assert(spill && "There must be at least one non-phi-node");

        /* insert reloads and wire them arbitrary*/
        pset_foreach(vi->values, irn)
                foreach_out_edge(irn, edge) {
                        ir_node *reload, *src = edge->src;
                        if (is_Phi(src))
                                continue;

                        /* all real uses must be reloaded */
                        reload = be_new_Reload(raenv->cls, raenv->irg, get_nodes_block(src), get_irn_mode(get_irn_n(spill, 0)), spill);
                        sched_add_before(src, reload);

                        /* remember the reload */
                        pset_insert_ptr(reloads, reload);
                }

        /* correct the reload->spill pointers... */
        be_ssa_constr_sets(raenv->dom_info, spills, reloads);


        /****** correct the variable <--> values mapping: ******
         *
         *  - if we had a phi class it gets split into several new variables
         *  - all reloads are new variables
         */
        n_spills = pset_count(spills);
        n_reloads = pset_count(reloads);

        /* first make room for new pointers in the cls_var array */
        new_size = raenv->n_cls_vars + n_reloads + ((n_spills>1) ? n_spills : 0);
        raenv->cls_vars = realloc(raenv->cls_vars, (new_size) * sizeof(*raenv->cls_vars));
        assert(raenv->cls_vars && "Out of mem!?");

        /* if we had a real phi-class, we must... */
        if (pset_count(spills) > 1) {
                /* ...remove the old variable corresponding to the phi class */
                vi->var_nr = SET_REMOVED;

                /* ...add new vars for each non-phi-member */
                pset_foreach(spills, irn) {
                        ir_node *spilled = get_irn_n(irn, 0);
                        raenv->cls_vars[raenv->n_cls_vars++] = var_add_value(raenv, get_irn_node_nr(spilled), spilled);
                }
        }

        /* add new variables for all reloads */
        pset_foreach(reloads, irn)
                raenv->cls_vars[raenv->n_cls_vars++] = var_add_value(raenv, get_irn_node_nr(irn), irn);



        del_pset(spills);
        del_pset(reloads);
}

#define INVALID_FILE_FORMAT assert(0 && "Invalid file format.")
#define BUFLEN 32
#define BUFCONV " %32s "

/**
 * Read in the actions performed by the external allocator.
 * Apply these transformations to the irg.
 * @return 1 if an allocation was read in. 0 otherwise.
 */
static int read_and_apply_results(be_raext_env_t *raenv, char *filename) {
        FILE *f;
        char buf[BUFLEN];
        int is_allocation = 0;

        if (!(f = fopen(filename, "rt"))) {
                fprintf(stderr, "Could not open file %s for reading\n", filename);
                exit(0xdeadbeef);
        }
        raenv->f = f;

        /* read the action */
        if (fscanf(f, BUFCONV, buf) != 1)
                INVALID_FILE_FORMAT;

        /* do we spill */
        if (!strcmp(buf, "spills")) {
                int var_nr;
                while (fscanf(f, " %d ", &var_nr) == 1)
                        var_add_spills_and_reloads(raenv, var_nr);
        } else

        /* or do we allocate */
        if (!strcmp(buf, "allocs")) {
                int var_nr, reg_nr;

                is_allocation = 1;
                while (fscanf(f, " %d %d ", &var_nr, &reg_nr) == 2) {
                        ir_node *irn;
                        pset *vals = get_var_values(raenv, var_nr);

                        assert(vals && "Variable nr does not exist!");
                        pset_foreach(vals, irn)
                                arch_set_irn_register(raenv->aenv, irn, arch_register_for_index(raenv->cls, reg_nr));
                }
        } else
                INVALID_FILE_FORMAT;

        if (!feof(f))
                INVALID_FILE_FORMAT;

        fclose(f);

        return is_allocation;
}

/******************************************************************************
    __  __       _
   |  \/  |     (_)
   | \  / | __ _ _ _ __
   | |\/| |/ _` | | '_ \
   | |  | | (_| | | | | |
   |_|  |_|\__,_|_|_| |_|
 *****************************************************************************/

/**
 * Default values for options
 */
static void (*ssa_destr)(be_raext_env_t*) = ssa_destr_simple;
static char callee[128] = "echo";


/**
 * Allocate registers with an external program using a text-file interface.
 *
 * Do some computations (SSA-destruction and mapping of values--vars)
 * Write file
 * Execute external program
 * Read in results and apply them
 *
 */
static void be_ra_extern_main(const be_irg_t *bi) {
        be_main_env_t *env = bi->main_env;
        ir_graph *irg = bi->irg;

        be_raext_env_t raenv;
        int clsnr, clss;
        var_info_t *vi;

        compute_doms(irg);

        raenv.irg      = irg;
        raenv.aenv     = env->arch_env;
        raenv.dom_info = be_compute_dominance_frontiers(irg);
        raenv.vars     = new_set(compare_var_infos, 64);

        /* Insert copies for constraints */
        handle_constraints(&raenv);
        dump_ir_block_graph_sched(irg, "-extern-constr");

        /* SSA destruction respectively transformation into "Conventional SSA" */
        ssa_destr(&raenv);
        dump_ir_block_graph_sched(irg, "-extern-ssadestr");


        /* Mapping of SSA-Values <--> Variables */
        phi_class_compute(irg);
        be_clear_links(irg);
        irg_walk_graph(irg, values_to_vars, NULL, &raenv);

        /* For all register classes */
        for(clsnr = 0, clss = arch_isa_get_n_reg_class(raenv.aenv->isa); clsnr < clss; ++clsnr) {
                int done = 0;
                char out[256], in[256];

                raenv.cls = arch_isa_get_reg_class(raenv.aenv->isa, clsnr);
                ir_snprintf(out, sizeof(out), "%F-%s.ra", irg, raenv.cls->name);
                ir_snprintf(in, sizeof(in), "%F-%s.ra.res", irg, raenv.cls->name);

                extract_vars_of_cls(&raenv);

                while (!done) {
                        dump_to_file(&raenv, out);
                        execute(callee, out, in);
                        done = read_and_apply_results(&raenv, in);
                }

                free(raenv.cls_vars);
        }

        dump_ir_block_graph_sched(irg, "-extern-alloc");

        /* Clean up */
        set_foreach(raenv.vars, vi)
                del_pset(vi->values);
        del_set(raenv.vars);
        be_free_dominance_frontiers(raenv.dom_info);
}

/******************************************************************************
     ____        _   _
    / __ \      | | (_)
   | |  | |_ __ | |_ _  ___  _ __  ___
   | |  | | '_ \| __| |/ _ \| '_ \/ __|
   | |__| | |_) | |_| | (_) | | | \__ \
    \____/| .__/ \__|_|\___/|_| |_|___/
          | |
          |_|
 *****************************************************************************/

#ifdef WITH_LIBCORE


static const lc_opt_enum_const_ptr_items_t ssa_destr_items[] = {
        { "simple",    (void*)ssa_destr_simple }, /* TODO make (void*) casts nicer */
        { "rastello",  (void*)ssa_destr_rastello },
        { NULL,      NULL }
};

static lc_opt_enum_const_ptr_var_t ssa_destr_var = {
        (const void **) &ssa_destr, ssa_destr_items
};

static const lc_opt_table_entry_t be_ra_extern_options[] = {
        LC_OPT_ENT_ENUM_FUNC_PTR("ssa_destr", "SSA destruction flavor", &ssa_destr_var),
        LC_OPT_ENT_STR("callee", "The external program to call", callee, sizeof(callee)),
        { NULL }
};

static void be_ra_extern_register_options(lc_opt_entry_t *root) {
        lc_opt_entry_t *grp = lc_opt_get_grp(root, "ext");

        lc_opt_add_table(grp, be_ra_extern_options);
}

#endif /* WITH_LIBCORE */

const be_ra_t be_ra_external_allocator = {
#ifdef WITH_LIBCORE
        be_ra_extern_register_options,
#endif
        be_ra_extern_main
};