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

   1 /**
   2  * Trivial node selector.
   3  * @author Christian Wuerdig
   4  * @date   29.08.2006
   5  * @cvs-id $Id$
   6  */
   7
   8 #include <stdlib.h>
   9
  10 #include "besched_t.h"
  11 #include "belistsched.h"
  12
  13 /**
  14  * The random selector:
  15  * Just assure that branches are executed last, otherwise select a random node
  16  */
  17 static ir_node *random_select(void *block_env, nodeset *ready_set, nodeset *live_set)
  18 {
  19         const arch_env_t *arch_env = block_env;
  20         ir_node          *irn      = NULL;
  21         int only_branches_left = 1;
  22
  23         /* assure that branches and constants are executed last */
  24         for (irn = nodeset_first(ready_set); irn; irn = nodeset_next(ready_set)) {
  25                 if (! arch_irn_class_is(arch_env, irn, branch)) {
  26                         only_branches_left = 0;
  27                         nodeset_break(ready_set);
  28                         break;
  29                 }
  30         }
  31
  32         if(only_branches_left) {
  33                 /* at last: schedule branches */
  34                 irn = nodeset_first(ready_set);
  35                 nodeset_break(ready_set);
  36         } else {
  37                 do {
  38                         // take 1 random node
  39                         int n = rand() % pset_count(ready_set);
  40                         int i = 0;
  41                         for(irn = nodeset_first(ready_set); irn; irn = nodeset_next(ready_set)) {
  42                                 if(i == n) {
  43                                         nodeset_break(ready_set);
  44                                         break;
  45                                 }
  46                                 ++i;
  47                         }
  48                 } while(arch_irn_class_is(arch_env, irn, branch));
  49         }
  50
  51         return irn;
  52 }
  53
  54 static void *random_init_graph(const list_sched_selector_t *vtab, const arch_env_t *arch_env, ir_graph *irg)
  55 {
  56         srand(time(0));
  57         return (void *)arch_env;
  58 }
  59
  60 static void *random_init_block(void *graph_env, ir_node *bl)
  61 {
  62         return graph_env;
  63 }
  64
  65 static const list_sched_selector_t random_selector_struct = {
  66         random_init_graph,
  67         random_init_block,
  68         random_select,
  69         NULL,                /* to_appear_in_schedule */
  70         NULL,                /* node_ready */
  71         NULL,                /* node_selected */
  72         NULL,                /* exectime */
  73         NULL,                /* latency */
  74         NULL,                /* finish_block */
  75         NULL                 /* finish_graph */
  76 };
  77
  78 const list_sched_selector_t *random_selector = &random_selector_struct;