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

   1 /**
   2  * Trivial node selector.
   3  * @author Matthias Braun
   4  * @date   29.08.2006
   5  * @cvs-id $Id$
   6  */
   7 #ifdef HAVE_CONFIG_H
   8 #include "config.h"
   9 #endif
  10
  11 #include <stdlib.h>
  12
  13 #include "besched_t.h"
  14 #include "belistsched.h"
  15
  16 /**
  17  * The random selector:
  18  * Just assure that branches are executed last, otherwise select a random node
  19  */
  20 static ir_node *random_select(void *block_env, ir_nodeset_t *ready_set,
  21                               ir_nodeset_t *live_set)
  22 {
  23         ir_nodeset_iterator_t iter;
  24         const arch_env_t *arch_env = block_env;
  25         ir_node          *irn      = NULL;
  26         int only_branches_left = 1;
  27
  28         /* assure that branches and constants are executed last */
  29         ir_nodeset_iterator_init(&iter, ready_set);
  30         while( (irn = ir_nodeset_iterator_next(&iter)) != NULL) {
  31                 if (! arch_irn_class_is(arch_env, irn, branch)) {
  32                         only_branches_left = 0;
  33                         break;
  34                 }
  35         }
  36
  37         if(only_branches_left) {
  38                 /* at last: schedule branches */
  39                 ir_nodeset_iterator_init(&iter, ready_set);
  40                 irn = ir_nodeset_iterator_next(&iter);
  41         } else {
  42                 do {
  43                         // take 1 random node
  44                         int n = rand() % ir_nodeset_size(ready_set);
  45                         int i = 0;
  46                         ir_nodeset_iterator_init(&iter, ready_set);
  47                         while( (irn = ir_nodeset_iterator_next(&iter)) != NULL) {
  48                                 if(i == n) {
  49                                         break;
  50                                 }
  51                                 ++i;
  52                         }
  53                 } while(arch_irn_class_is(arch_env, irn, branch));
  54         }
  55
  56         return irn;
  57 }
  58
  59 static void *random_init_graph(const list_sched_selector_t *vtab, const arch_env_t *arch_env, ir_graph *irg)
  60 {
  61         /* Using time(NULL) as a seed here gives really random results,
  62            but is NOT deterministic which makes debugging impossible.
  63            Moreover no-one want non-deterministic compilers ... */
  64         srand(0x4711);
  65         return (void *)arch_env;
  66 }
  67
  68 static void *random_init_block(void *graph_env, ir_node *bl)
  69 {
  70         return graph_env;
  71 }
  72
  73 static const list_sched_selector_t random_selector_struct = {
  74         random_init_graph,
  75         random_init_block,
  76         random_select,
  77         NULL,                /* to_appear_in_schedule */
  78         NULL,                /* node_ready */
  79         NULL,                /* node_selected */
  80         NULL,                /* exectime */
  81         NULL,                /* latency */
  82         NULL,                /* finish_block */
  83         NULL                 /* finish_graph */
  84 };
  85
  86 const list_sched_selector_t *random_selector = &random_selector_struct;