2 * Base routines for register allocation.
3 * @author Sebastian Hack
18 #include "besched_t.h"
21 static sched_timestep_t get_time_step(const ir_node *irn)
26 return sched_get_time_step(irn);
29 int value_dominates(const ir_node *a, const ir_node *b)
32 const ir_node *ba = get_block(a);
33 const ir_node *bb = get_block(b);
36 * a and b are not in the same block,
37 * so dominance is determined by the dominance of the blocks.
40 res = block_dominates(ba, bb);
43 * Dominance is determined by the time steps of the schedule.
46 sched_timestep_t as = get_time_step(a);
47 sched_timestep_t bs = get_time_step(b);
55 * Check, if two values interfere.
56 * @param a The first value.
57 * @param b The second value.
58 * @return 1, if a and b interfere, 0 if not.
60 int values_interfere(const be_lv_t *lv, const ir_node *a, const ir_node *b)
62 int a2b = value_dominates(a, b);
63 int b2a = value_dominates(b, a);
65 /* If there is no dominance relation, they do not interfere. */
67 const ir_edge_t *edge;
71 * Adjust a and b so, that a dominates b if
72 * a dominates b or vice versa.
80 bb = get_nodes_block(b);
83 * If a is live end in b's block it is
84 * live at b's definition (a dominates b)
86 if(be_is_live_end(lv, bb, a))
90 * Look at all usages of a.
91 * If there's one usage of a in the block of b, then
92 * we check, if this use is dominated by b, if that's true
93 * a and b interfere. Note that b must strictly dominate the user,
94 * since if b is the last user of in the block, b and a do not
96 * Uses of a not in b's block can be disobeyed, because the
97 * check for a being live at the end of b's block is already
100 foreach_out_edge(a, edge) {
101 const ir_node *user = get_edge_src_irn(edge);
102 if(get_nodes_block(user) == bb && !is_Phi(user) && b != user && value_dominates(b, user))