2 * This file is part of libFirm.
3 * Copyright (C) 2012 University of Karlsruhe.
8 * @brief Backend IRG modification routines.
9 * @author Sebastian Hack, Daniel Grund, Matthias Braun, Christian Wuerdig
12 * This file contains the following IRG modifications for be routines:
13 * - insertion of Perm nodes
14 * - empty block elimination
15 * - a simple dead node elimination (set inputs of unreachable nodes to BAD)
36 #include "iredges_t.h"
37 #include "irgraph_t.h"
44 #include "bechordal_t.h"
51 #include "bessaconstr.h"
56 DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)
58 static int cmp_node_nr(const void *a, const void *b)
60 ir_node **p1 = (ir_node**)a;
61 ir_node **p2 = (ir_node**)b;
62 long n1 = get_irn_node_nr(*p1);
63 long n2 = get_irn_node_nr(*p2);
64 return (n1>n2) - (n1<n2);
69 |_ _|_ __ ___ ___ _ __| |_ | _ \ ___ _ __ _ __ ___
70 | || '_ \/ __|/ _ \ '__| __| | |_) / _ \ '__| '_ ` _ \
71 | || | | \__ \ __/ | | |_ | __/ __/ | | | | | | |
72 |___|_| |_|___/\___|_| \__| |_| \___|_| |_| |_| |_|
76 ir_node *insert_Perm_before(ir_graph *irg, const arch_register_class_t *cls,
79 be_lv_t *lv = be_get_irg_liveness(irg);
82 ir_node *perm, **nodes;
85 DBG((dbg, LEVEL_1, "Insert Perm before: %+F\n", pos));
87 ir_nodeset_init(&live);
88 be_liveness_nodes_live_before(lv, cls, pos, &live);
90 n = ir_nodeset_size(&live);
92 ir_nodeset_destroy(&live);
96 nodes = XMALLOCN(ir_node*, n);
98 DBG((dbg, LEVEL_1, "live:\n"));
100 foreach_ir_nodeset(&live, irn, iter) {
101 DBG((dbg, LEVEL_1, "\t%+F\n", irn));
105 ir_nodeset_destroy(&live);
106 /* make the input order deterministic */
107 qsort(nodes, n, sizeof(nodes[0]), cmp_node_nr);
109 ir_node *const bl = get_nodes_block(pos);
110 perm = be_new_Perm(cls, bl, n, nodes);
111 sched_add_before(pos, perm);
114 for (i = 0; i < n; ++i) {
115 ir_node *perm_op = get_irn_n(perm, i);
116 be_ssa_construction_env_t senv;
118 ir_mode *mode = get_irn_mode(perm_op);
119 ir_node *proj = new_r_Proj(perm, mode, i);
121 be_ssa_construction_init(&senv, irg);
122 be_ssa_construction_add_copy(&senv, perm_op);
123 be_ssa_construction_add_copy(&senv, proj);
124 be_ssa_construction_fix_users(&senv, perm_op);
125 be_ssa_construction_update_liveness_phis(&senv, lv);
126 be_liveness_update(lv, perm_op);
127 be_liveness_update(lv, proj);
128 be_ssa_construction_destroy(&senv);
134 static int blocks_removed;
137 * Post-block-walker: Find blocks containing only one jump and
140 static void remove_empty_block(ir_node *block)
146 ir_node *jump = NULL;
147 ir_graph *irg = get_irn_irg(block);
150 if (irn_visited_else_mark(block))
153 if (get_Block_n_cfgpreds(block) != 1)
156 sched_foreach(block, node) {
158 && !(arch_get_irn_flags(node) & arch_irn_flags_simple_jump))
161 /* we should never have 2 jumps in a block */
162 panic("found 2 jumps in a block");
170 entity = get_Block_entity(block);
171 pred = get_Block_cfgpred(block, 0);
173 foreach_out_edge_safe(jump, edge) {
174 int pos = get_edge_src_pos(edge);
176 assert(succ_block == NULL);
177 succ_block = get_edge_src_irn(edge);
178 if (get_Block_entity(succ_block) != NULL && entity != NULL) {
180 * Currently we can add only one label for a block.
181 * Therefore we cannot combine them if both block already have one.
186 set_irn_n(succ_block, pos, pred);
189 if (entity != NULL) {
190 /* move the label to the successor block */
191 set_Block_entity(succ_block, entity);
194 /* there can be some non-scheduled Pin nodes left in the block, move them
195 * to the succ block (Pin) or pred block (Sync) */
196 foreach_out_edge_safe(block, edge) {
197 ir_node *const node = get_edge_src_irn(edge);
201 /* we simply kill Pins, because there are some strange interactions
202 * between jump threading, which produce PhiMs with Pins, we simply
203 * kill the pins here, everything is scheduled anyway */
205 exchange(node, get_Pin_op(node));
209 set_nodes_block(node, get_nodes_block(pred));
212 if (is_End(node)) { /* End-keep, reroute it to the successor */
213 int pos = get_edge_src_pos(edge);
214 set_irn_n(node, pos, succ_block);
217 panic("Unexpected node %+F in block %+F with empty schedule", node, block);
220 set_Block_cfgpred(block, 0, new_r_Bad(irg, mode_X));
224 /* check predecessor */
225 remove_empty_block(get_nodes_block(pred));
229 arity = get_Block_n_cfgpreds(block);
230 for (i = 0; i < arity; ++i) {
231 ir_node *pred = get_Block_cfgpred_block(block, i);
232 remove_empty_block(pred);
236 /* removes basic blocks that just contain a jump instruction */
237 int be_remove_empty_blocks(ir_graph *irg)
244 ir_reserve_resources(irg, IR_RESOURCE_IRN_VISITED);
245 inc_irg_visited(irg);
246 remove_empty_block(get_irg_end_block(irg));
247 end = get_irg_end(irg);
248 arity = get_irn_arity(end);
249 for (i = 0; i < arity; ++i) {
250 ir_node *pred = get_irn_n(end, i);
253 remove_empty_block(pred);
255 ir_free_resources(irg, IR_RESOURCE_IRN_VISITED);
257 if (blocks_removed) {
258 /* invalidate analysis info */
259 clear_irg_properties(irg, IR_GRAPH_PROPERTY_CONSISTENT_DOMINANCE);
261 return blocks_removed;
264 //---------------------------------------------------------------------------
266 typedef struct remove_dead_nodes_env_t_ {
270 } remove_dead_nodes_env_t;
273 * Post-walker: remember all visited nodes in a bitset.
275 static void mark_dead_nodes_walker(ir_node *node, void *data)
277 remove_dead_nodes_env_t *env = (remove_dead_nodes_env_t*) data;
278 bitset_set(env->reachable, get_irn_idx(node));
283 * Walk through the schedule of every block and remove all dead nodes from it.
285 static void remove_dead_nodes_walker(ir_node *block, void *data)
287 remove_dead_nodes_env_t *env = (remove_dead_nodes_env_t*) data;
289 sched_foreach_safe(block, node) {
290 if (bitset_is_set(env->reachable, get_irn_idx(node)))
294 be_liveness_remove(env->lv, node);
298 if (get_irn_mode(node) == mode_T) {
299 foreach_out_edge_safe(node, edge) {
300 ir_node *proj = get_edge_src_irn(edge);
304 be_liveness_remove(env->lv, proj);
312 void be_remove_dead_nodes_from_schedule(ir_graph *irg)
314 remove_dead_nodes_env_t env;
315 env.reachable = bitset_alloca(get_irg_last_idx(irg));
316 env.lv = be_get_irg_liveness(irg);
319 // mark all reachable nodes
320 irg_walk_graph(irg, mark_dead_nodes_walker, NULL, &env);
322 // walk schedule and remove non-marked nodes
323 irg_block_walk_graph(irg, remove_dead_nodes_walker, NULL, &env);
326 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_irgmod)
327 void be_init_irgmod(void)
329 FIRM_DBG_REGISTER(dbg, "firm.be.irgmod");