2 * Copyright (C) 1995-2008 University of Karlsruhe. All right reserved.
4 * This file is part of libFirm.
6 * This file may be distributed and/or modified under the terms of the
7 * GNU General Public License version 2 as published by the Free Software
8 * Foundation and appearing in the file LICENSE.GPL included in the
9 * packaging of this file.
11 * Licensees holding valid libFirm Professional Edition licenses may use
12 * this file in accordance with the libFirm Commercial License.
13 * Agreement provided with the Software.
15 * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
16 * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * @brief Extended basis block support.
23 * @author Michael Beck
29 #include "irextbb_t.h"
32 #include "irgraph_t.h"
33 #include "iredges_t.h"
39 * Environment for extbb construction.
42 struct obstack *obst; /**< the obstack where allocations took place */
43 ir_extblk *head; /**< head of the list of all extended blocks */
44 ir_node *start_block; /**< the start block of the current graph */
47 int (is_ir_extbb)(const void *thing) {
48 return _is_ir_extbb(thing);
52 * allocate a new extended block header.
54 static void allocate_extblk(ir_node *block, env_t *env) {
55 ir_extblk *extblk = obstack_alloc(env->obst, sizeof(*extblk));
57 extblk->kind = k_ir_extblk;
59 extblk->blks = (ir_node **)env->head;
63 set_Block_extbb(block, extblk);
64 set_irn_link(block, NULL);
68 * Returns the number of block successors.
69 * we are interested only in 1, 2 and >2.
71 static int get_block_n_succs(ir_node *block) {
72 if (edges_activated(current_ir_graph)) {
73 const ir_edge_t *edge;
75 edge = get_block_succ_first(block);
78 edge = get_block_succ_next(block, edge);
81 edge = get_block_succ_next(block, edge);
84 return get_Block_n_cfg_outs(block);
88 * Pre block-walker. Calculates the extended block info.
90 static void pre_walk_calc_extbb(ir_node *block, void *ctx) {
91 int n = get_Block_n_cfgpreds(block);
94 if (n <= 0 || n > 1 || block == env->start_block) {
96 * block is a JOIN-node ie the control flow from
97 * many other blocks joins here. block is a leader.
98 * Note that we handle unreachable blocks (n <= 0) here too.
100 allocate_extblk(block, env);
102 else { /* we have only one control flow predecessor */
103 ir_node *add_to = get_Block_cfgpred_block(block, 0);
105 /* blocks with only one BAD predecessors are leaders too */
106 if (is_Bad(add_to)) {
107 allocate_extblk(block, env);
110 * Only one control flow predecessor. This block belongs
111 * to the same extended basic block as its predecessor.
113 ir_node *cf_op = skip_Proj(get_Block_cfgpred(block, 0));
115 if (!irn_visited_else_mark(cf_op)) {
116 ir_node *pred_bl = get_nodes_block(cf_op);
117 if (get_block_n_succs(pred_bl) > 2) {
118 /* More than two successors means we have a jump table.
119 * we cannot include a jump target into the current extended
120 * basic block, so create a new one here.
122 allocate_extblk(block, env);
124 /* either the previous block has only one successor or
125 * this is the first successor after an if, include it.
127 set_Block_extbb(block, NULL);
130 /* already marked, so begin a new extended block here */
131 allocate_extblk(block, env);
137 /** A special extended block used as sentinel */
138 static ir_extblk _sentinel = { k_ir_extblk, 0xFEA1DEAD, NULL, NULL };
141 * Post block-walker. Calculates the extended block info.
142 * During construction, we use the (free) block input of all basic blocks
143 * to point to there previous block.
145 static void post_walk_calc_extbb(ir_node *block, void *ctx)
147 ir_extblk *extbb = get_Block_extbb(block);
149 ir_extblk *sentinel = &_sentinel;
152 ir_node *curr, *prev, *list;
155 * Search the leader. It can happen, that we fall into an endless
156 * loop, because we enter an unreachable loop that is not yet detected.
157 * We break the loop using a sentinel.
159 for (curr = block; !extbb; curr = prev) {
160 prev = get_Block_cfgpred_block(curr, 0);
161 extbb = get_Block_extbb(prev);
162 set_Block_extbb(curr, sentinel);
165 if (extbb == sentinel) {
166 /* We detect a dead loop. We fix this by allocating a
167 * special Extended block
169 ir_printf("Dead loop detected starting with %+F::%+F\n", get_irg_entity(current_ir_graph), block);
171 allocate_extblk(block, env);
172 extbb = get_Block_extbb(block);
173 set_Block_extbb(block, sentinel);
176 /* replace all sentinels by the extbb info */
180 if (get_Block_extbb(prev) != sentinel)
182 set_irn_link(prev, list);
184 prev = get_Block_cfgpred_block(prev, 0);
186 /* arg, the list is in wrong order, turn around and add to the extbb list */
187 for (curr = list; curr; curr = prev) {
188 prev = get_irn_link(curr);
189 set_irn_link(curr, extbb->link);
191 set_Block_extbb(curr, extbb);
198 * Compute the extended basic blocks for a graph
200 void compute_extbb(ir_graph *irg) {
202 ir_extblk *extbb, *next;
205 obstack_free(irg->extbb_obst, NULL);
207 irg->extbb_obst = XMALLOC(struct obstack);
208 obstack_init(irg->extbb_obst);
210 env.obst = irg->extbb_obst;
212 env.start_block = get_irg_start_block(irg);
214 if (! edges_activated(irg)) {
215 /* we don't have edges */
216 assure_irg_outs(irg);
219 /* we must mark nodes, so increase the visited flag */
220 inc_irg_visited(irg);
221 irg_block_walk_graph(irg, pre_walk_calc_extbb, post_walk_calc_extbb, &env);
224 * Ok, we have now the list of all extended blocks starting with env.head
225 * every extended block "knowns" the number of blocks in visited and
226 * the blocks are linked in link.
227 * Now we can create arrays that hold the blocks, some kind of "out" edges
228 * for the extended block
230 for (extbb = env.head; extbb; extbb = next) {
231 int i, len = (int)extbb->visited;
234 next = (ir_extblk *)extbb->blks;
236 extbb->blks = NEW_ARR_D(ir_node *, env.obst, len);
238 for (block = extbb->link, i = 0; i < len; ++i) {
239 ir_node *nblock = get_irn_link(block);
241 /* ensure that the leader is the first one */
242 extbb->blks[len - 1 - i] = block;
243 set_irn_link(block, NULL);
249 for (i = len - 1; i > 0; --i) {
250 ir_node *blk = extbb->blks[i];
252 if (get_Block_n_cfgpreds(blk) != 1) {
253 assert(!"Block for more than one predecessors is no leader");
254 } else if (get_Block_cfgpred_block(blk, 0) != extbb->blks[i - 1]) {
255 assert(!"extbb block order wrong");
264 irg->extblk_state = extblk_valid;
267 /* free all extended block info. */
268 void free_extbb(ir_graph *irg) {
269 if (irg->extbb_obst) {
270 obstack_free(irg->extbb_obst, NULL);
271 xfree(irg->extbb_obst);
272 irg->extbb_obst = NULL;
274 irg->extblk_state = extblk_none;
277 /* Return the extended block of a node. */
278 ir_extblk *get_nodes_extbb(const ir_node *node) {
279 const ir_node *block = is_Block(node) ? node : get_nodes_block(node);
280 return get_Block_extbb(block);
283 /* Gets the visited counter of an extended block. */
284 ir_visited_t (get_extbb_visited)(const ir_extblk *blk) {
285 return _get_extbb_visited(blk);
288 /* Sets the visited counter of an extended block. */
289 void (set_extbb_visited)(ir_extblk *blk, ir_visited_t visited) {
290 _set_extbb_visited(blk, visited);
293 /* Mark an extended block as visited in a graph. */
294 void (mark_extbb_visited)(ir_extblk *blk) {
295 _mark_extbb_visited(blk);
298 /* Returns non-zero if an extended was visited. */
299 int (extbb_visited)(const ir_extblk *blk) {
300 return _extbb_visited(blk);
303 /* Returns non-zero if an extended block was NOT visited. */
304 int (extbb_not_visited)(const ir_extblk *blk) {
305 return _extbb_not_visited(blk);
308 /* Returns the link field of an extended block. */
309 void *(get_extbb_link)(const ir_extblk *blk) {
310 return _get_extbb_link(blk);
313 /* Sets the link field of an extended block. */
314 void (set_extbb_link)(ir_extblk *blk, void *link) {
315 _set_extbb_link(blk, link);
318 /* Return the number of basic blocks of an extended block */
319 int (get_extbb_n_blocks)(const ir_extblk *blk) {
320 return _get_extbb_n_blocks(blk);
323 /* Return the i'th basic block of an extended block */
324 ir_node *(get_extbb_block)(const ir_extblk *blk, int pos) {
325 return _get_extbb_block(blk, pos);
328 /* Return the leader basis block of an extended block. */
329 ir_node *(get_extbb_leader)(const ir_extblk *blk) {
330 return _get_extbb_leader(blk);
333 /* Return the node number of an extended block. */
334 long get_extbb_node_nr(const ir_extblk *blk) {
335 return get_irn_node_nr(get_extbb_leader(blk));
338 static void irg_extblock_walk_2(ir_extblk *blk, extbb_walk_func *pre, extbb_walk_func *post, void *env) {
342 if (extbb_not_visited(blk)) {
343 mark_extbb_visited(blk);
345 if (pre) pre(blk, env);
347 node = get_extbb_leader(blk);
348 for (i = get_Block_n_cfgpreds(node) - 1; i >= 0; --i) {
349 /* find the corresponding predecessor block. */
350 ir_node *pred = get_Block_cfgpred_block(node, i);
351 if (is_Block(pred)) {
353 irg_extblock_walk_2(get_Block_extbb(pred), pre, post, env);
356 assert(is_Bad(pred));
360 if (post) post(blk, env);
364 /* walks only over extended Block nodes in the graph. Has it's own visited
365 flag, so that it can be interleaved with the other walker. */
366 void irg_extblock_walk(ir_extblk *blk, extbb_walk_func *pre, extbb_walk_func *post, void *env) {
367 ir_node *pred, *start_bl = get_irg_start_block(current_ir_graph);
368 ir_extblk *start_blk = get_Block_extbb(start_bl);
372 inc_irg_block_visited(current_ir_graph);
374 /* assure the start block is the first one */
375 mark_extbb_visited(start_blk);
377 post(start_blk, env);
378 irg_extblock_walk_2(blk, pre, post, env);
380 /* keepalive: the endless loops ... */
381 if (blk == get_Block_extbb(get_irg_end_block(current_ir_graph))) {
382 ir_node *node = get_irg_end(current_ir_graph);
383 int arity = get_irn_arity(node);
384 for (i = 0; i < arity; i++) {
385 pred = get_irn_n(node, i);
387 irg_extblock_walk_2(get_Block_extbb(pred), pre, post, env);
388 else if (is_Phi(pred)) {
389 /* Sometimes the blocks died, but are still reachable through Phis.
390 * Make sure the algorithms that try to remove these reach them. */
391 ir_node *block = get_nodes_block(pred);
394 irg_extblock_walk_2(get_Block_extbb(block), pre, post, env);
403 /* Walks only over reachable Extended Basic Block nodes in the graph. */
404 void irg_extblock_walk_graph(ir_graph *irg, extbb_walk_func *pre, extbb_walk_func *post, void *env) {
405 ir_node *endbl = get_irg_end_block(irg);
406 ir_extblk *blk = get_Block_extbb(endbl);
407 ir_graph *rem = current_ir_graph;
408 current_ir_graph = irg;
409 irg_extblock_walk(blk, pre, post, env);
410 current_ir_graph = rem;