2 * Base routines for register allocation.
3 * @author Sebastian Hack
18 #include "besched_t.h"
21 int value_dominates(const ir_node *a, const ir_node *b)
24 const ir_node *ba = get_block(a);
25 const ir_node *bb = get_block(b);
28 * a and b are not in the same block,
29 * so dominance is determined by the dominance of the blocks.
32 res = block_dominates(ba, bb);
35 * Dominance is determined by the time steps of the schedule.
38 sched_timestep_t as = sched_get_time_step(a);
39 sched_timestep_t bs = sched_get_time_step(b);
47 * Check, if two values interfere.
48 * @param a The first value.
49 * @param b The second value.
50 * @return 1, if a and b interfere, 0 if not.
52 int values_interfere(const ir_node *a, const ir_node *b)
54 int a2b = value_dominates(a, b);
55 int b2a = value_dominates(b, a);
58 * Adjust a and b so, that a dominates b if
59 * a dominates b or vice versa.
68 * If either a dmoninates b or vice versa
69 * check if there is usage which is dominated by b.
71 * remind, that if a and b are in a dom relation, a always dominates b
72 * here due to the if above.
75 const ir_edge_t *edge;
77 /* Look at all usages of a */
78 foreach_out_edge(a, edge) {
79 const ir_node *user = edge->src;
82 * If the user is a phi we must check the last instruction in the
83 * corresponding phi predecessor block since the phi is not a
87 ir_node *phi_block = get_nodes_block(user);
88 user = sched_last(get_Block_cfgpred_block(phi_block, edge->pos));
91 /* If b dominates a user of a, we can safely return 1 here. */
92 if(value_dominates(b, user))