4 * @author Sebastian Hack
6 * Principal routines for liveness and interference checks.
8 * Copyright (C) 2007 Universitaet Karlsruhe
9 * Released under the GPL
12 #ifndef _BELIVECHK_T_H
13 #define _BELIVECHK_T_H
15 #include "irgraph_t.h"
16 #include "iredges_t.h"
25 * Check dominance of two nodes in the same block.
26 * @param a The first node.
27 * @param b The second node.
28 * @return 1 if a comes before b in the same block or if a == b, 0 else.
30 static inline int _value_dominates_intrablock(const ir_node *a, const ir_node *b)
32 /* TODO: ? : can be removed?! */
33 sched_timestep_t as = sched_is_scheduled(a) ? sched_get_time_step(a) : 0;
34 sched_timestep_t bs = sched_is_scheduled(b) ? sched_get_time_step(b) : 0;
39 * Check strict dominance of two nodes in the same block.
40 * @param a The first node.
41 * @param b The second node.
42 * @return 1 if a comes before b in the same block, 0 else.
44 static inline int _value_strictly_dominates_intrablock(const ir_node *a, const ir_node *b)
46 /* TODO: ? : can be removed?! */
47 sched_timestep_t as = sched_is_scheduled(a) ? sched_get_time_step(a) : 0;
48 sched_timestep_t bs = sched_is_scheduled(b) ? sched_get_time_step(b) : 0;
53 * Check, if one value dominates the other.
54 * The dominance is not strict here.
55 * @param a The first node.
56 * @param b The second node.
57 * @return 1 if a dominates b or if a == b, 0 else.
59 static inline int _value_dominates(const ir_node *a, const ir_node *b)
61 const ir_node *block_a = get_block_const(a);
62 const ir_node *block_b = get_block_const(b);
65 * a and b are not in the same block,
66 * so dominance is determined by the dominance of the blocks.
68 if(block_a != block_b) {
69 return block_dominates(block_a, block_b);
73 * Dominance is determined by the time steps of the schedule.
75 return _value_dominates_intrablock(a, b);
79 * Check, if one value dominates the other.
80 * The dominance is strict here.
81 * @param a The first node.
82 * @param b The second node.
83 * @return 1 if a dominates b, 0 else.
85 static inline int _value_strictly_dominates(const ir_node *a, const ir_node *b)
87 const ir_node *block_a = get_block_const(a);
88 const ir_node *block_b = get_block_const(b);
91 * a and b are not in the same block,
92 * so dominance is determined by the dominance of the blocks.
94 if(block_a != block_b) {
95 return block_dominates(block_a, block_b);
99 * Dominance is determined by the time steps of the schedule.
101 return _value_strictly_dominates_intrablock(a, b);
105 * Check, if two values interfere.
106 * @param lv Liveness information
107 * @param a The first value.
108 * @param b The second value.
109 * @return 1, if a and b interfere, 0 if not.
111 static inline int be_values_interfere(const be_lv_t *lv, const ir_node *a, const ir_node *b)
113 int a2b = _value_dominates(a, b);
114 int b2a = _value_dominates(b, a);
118 * Adjust a and b so, that a dominates b if
119 * a dominates b or vice versa.
122 const ir_node *t = a;
128 /* If there is no dominance relation, they do not interfere. */
130 ir_node *bb = get_nodes_block(b);
133 * If a is live end in b's block it is
134 * live at b's definition (a dominates b)
136 if(be_is_live_end(lv, bb, a)) {
142 * Look at all usages of a.
143 * If there's one usage of a in the block of b, then
144 * we check, if this use is dominated by b, if that's true
145 * a and b interfere. Note that b must strictly dominate the user,
146 * since if b is the last user of in the block, b and a do not
148 * Uses of a not in b's block can be disobeyed, because the
149 * check for a being live at the end of b's block is already
152 foreach_out_edge(a, edge) {
153 const ir_node *user = get_edge_src_irn(edge);
154 if(get_nodes_block(user) == bb && !is_Phi(user) && _value_strictly_dominates(b, user)) {
168 * Check if a node dominates a use.
169 * Note that the use of a phi is in its corresponding predecessor.
170 * @param irn The node.
171 * @param edge The use.
172 * @return 1, if @p irn dominates the use @p edge.
174 static inline int _dominates_use(const ir_node *irn, const ir_edge_t *edge)
176 ir_node *use = get_edge_src_irn(edge);
179 int pos = get_edge_src_pos(edge);
180 ir_node *phi_bl = get_nodes_block(use);
181 ir_node *use_bl = get_Block_cfgpred_block(phi_bl, pos);
182 ir_node *irn_bl = get_nodes_block(irn);
183 return block_dominates(irn_bl, use_bl);
186 return _value_dominates(irn, use);
190 * Check if a node strictly dominates a use.
191 * Note that the use of a phi is in its corresponding predecessor.
192 * @param irn The node.
193 * @param edge The use.
194 * @return 1, if @p irn strictly dominates the use @p edge.
196 static inline int _strictly_dominates_use(const ir_node *irn, const ir_edge_t *edge)
198 return get_edge_src_irn(edge) != irn && _dominates_use(irn, edge);
202 * Check, if a node is live in front of another.
203 * @param irg The backend irg.
204 * @param irn The node.
205 * @param where The location to check for.
206 * @return 1, if @p irn is live in front of @p where.
208 static inline int _be_lv_chk_before_irn(ir_graph *irg, const ir_node *irn,
209 const ir_node *where)
211 const be_lv_t *lv = be_get_irg_liveness(irg);
213 /* the node must strictly dominate the location, else it cannot be live there. */
214 if (!_value_dominates(irn, where) || irn == where)
218 * now that it is clear that it strictly dominates the location it is surely live
219 * if it is also live end at the block.
221 if (be_is_live_end(lv, get_nodes_block(where), irn))
225 * If the node is not live out, we have to check if there
226 * is a use which is dominated by the location.
228 foreach_out_edge (irn, edge) {
229 if (_dominates_use(where, edge))
237 * Check, if a node is live after another node.
238 * @param irg The backend irg.
239 * @param irn The node.
240 * @param where The location to check for.
241 * @return 1, if @p irn is live after @p where.
243 static inline int _be_lv_chk_after_irn(ir_graph *irg, const ir_node *irn,
244 const ir_node *where)
246 const be_lv_t *lv = be_get_irg_liveness(irg);
248 if (!_value_dominates(irn, where))
251 if (be_is_live_end(lv, get_nodes_block(where), irn))
254 foreach_out_edge (irn, edge) {
255 if (_strictly_dominates_use(where, edge))
262 #define value_dominates_intrablock(a, b) _value_dominates_intrablock(a, b)
263 #define value_dominates(a, b) _value_dominates(a, b)
264 #define dominates_use(a, e) _dominates_use(a, e)
265 #define strictly_dominates_use(a, e) _strictly_dominates_use(a, e)
266 #define be_lv_chk_before_irn(irg, a, b) _be_lv_chk_before_irn(irg, a, b)
267 #define be_lv_chk_after_irn(irg, a, b) _be_lv_chk_after_irn(irg, a, b)