nsz Git - libfirm/blob - ir/be/beschedrand.c

   1 /*
   2  * This file is part of libFirm.
   3  * Copyright (C) 2012 University of Karlsruhe.
   4  */
   5
   6 /**
   7  * @file
   8  * @brief       Random node selector.
   9  * @author      Matthias Braun
  10  * @date        29.08.2006
  11  */
  12 #include "config.h"
  13
  14 #include <stdlib.h>
  15
  16 #include "besched.h"
  17 #include "belistsched.h"
  18 #include "bemodule.h"
  19
  20 /**
  21  * The random selector:
  22  * Just assure that branches are executed last, otherwise select a random node
  23  */
  24 static ir_node *random_select(void *block_env, ir_nodeset_t *ready_set)
  25 {
  26         int only_branches_left = 1;
  27         (void)block_env;
  28
  29         /* assure that branches and constants are executed last */
  30         foreach_ir_nodeset(ready_set, irn, iter) {
  31                 if (!is_cfop(irn)) {
  32                         only_branches_left = 0;
  33                         break;
  34                 }
  35         }
  36
  37         ir_node *rand_node = NULL;
  38         if (only_branches_left) {
  39                 /* at last: schedule branches */
  40                 rand_node = ir_nodeset_first(ready_set);
  41         } else {
  42                 do {
  43                         /* take 1 random node */
  44                         int n = rand() % ir_nodeset_size(ready_set);
  45                         int i = 0;
  46                         foreach_ir_nodeset(ready_set, irn, iter) {
  47                                 rand_node = irn;
  48                                 if (i == n) {
  49                                         break;
  50                                 }
  51                                 ++i;
  52                         }
  53                 } while (is_cfop(rand_node));
  54         }
  55
  56         return rand_node;
  57 }
  58
  59 static void *random_init_graph(ir_graph *irg)
  60 {
  61         (void)irg;
  62         /* TODO: add commandline option for the seed */
  63         srand(0x4711);
  64         return NULL;
  65 }
  66
  67 static void *random_init_block(void *graph_env, ir_node *block)
  68 {
  69         (void)graph_env;
  70         (void)block;
  71         return NULL;
  72 }
  73
  74 static void sched_random(ir_graph *irg)
  75 {
  76         static const list_sched_selector_t random_selector = {
  77                 random_init_graph,
  78                 random_init_block,
  79                 random_select,
  80                 NULL,                /* node_ready */
  81                 NULL,                /* node_selected */
  82                 NULL,                /* finish_block */
  83                 NULL                 /* finish_graph */
  84         };
  85         be_list_sched_graph(irg, &random_selector);
  86 }
  87
  88 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_sched_rand)
  89 void be_init_sched_rand(void)
  90 {
  91         be_register_scheduler("random", sched_random);
  92 }