2 * Base routines for register allocation.
3 * @author Sebastian Hack
17 #include "besched_t.h"
20 int value_dominates(const ir_node *a, const ir_node *b)
23 const ir_node *ba = get_nodes_block(a);
24 const ir_node *bb = get_nodes_block(a);
27 * a and b are not in the same block,
28 * so dominance is determined by the dominance of the blocks.
31 res = block_dominates(ba, bb);
34 * Dominance is determined by the time steps of the schedule.
37 sched_timestep_t as = sched_get_time_step(a);
38 sched_timestep_t bs = sched_get_time_step(b);
46 * Check, if two values interfere.
47 * @param a The first value.
48 * @param b The second value.
49 * @return 1, if a and b interfere, 0 if not.
51 int values_interfere(const ir_node *a, const ir_node *b)
53 int a2b = value_dominates(a, b);
54 int b2a = value_dominates(b, a);
57 * Adjust a and b so, that a dominates b if
58 * a dominates b or vice versa.
67 * If either a dmoninates b or vice versa
68 * check if there is usage which is dominated by b.
70 * remind, that if a and b are in a dom relation, a always dominates b
71 * here due to the if above.
74 const ir_edge_t *edge;
76 /* Look at all usages of a */
77 foreach_out_edge(a, edge) {
78 const ir_node *user = edge->src;
81 * If the user is a phi we must check the last instruction in the
82 * corresponding phi predecessor block since the phi is not a
86 ir_node *phi_block = get_nodes_block(user);
87 user = sched_last(get_Block_cfgpred_block(phi_block, edge->pos));
90 /* If b dominates a user of a, we can safely return 1 here. */
91 if(value_dominates(b, user))