- int a2b = value_dominates(a, b);
- int b2a = value_dominates(b, a);
-
- /* If there is no dominance relation, they do not interfere. */
- if((a2b | b2a) > 0) {
- const ir_edge_t *edge;
- ir_node *bb;
-
- /*
- * Adjust a and b so, that a dominates b if
- * a dominates b or vice versa.
- */
- if(b2a) {
- const ir_node *t = a;
- a = b;
- b = t;
- }
-
- bb = get_nodes_block(b);
-
- /*
- * If a is live end in b's block it is
- * live at b's definition (a dominates b)
- */
- if(is_live_end(bb, a))
- return 1;
-
- /*
- * Look at all usages of a.
- * If there's one usage of a in the block of b, then
- * we check, if this use is dominated by b, if that's true
- * a and b interfere. Note that b must strictly dominate the user,
- * since if b is the last user of in the block, b and a do not
- * interfere.
- * Uses of a not in b's block can be disobeyed, because the
- * check for a being live at the end of b's block is already
- * performed.
- */
- foreach_out_edge(a, edge) {
- const ir_node *user = edge->src;
- if(get_nodes_block(user) == bb
- && !is_Phi(user)
- && b != user
- && value_dominates(b, user)) {
- return 1;
- }
- }