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
31 #include "irextbb_t.h"
34 #include "irgraph_t.h"
35 #include "iredges_t.h"
41 * Environment for extbb construction.
44 struct obstack *obst; /**< the obstack where allocations took place */
45 ir_extblk *head; /**< head of the list of all extended blocks */
46 ir_node *start_block; /**< the start block of the current graph */
49 int (is_ir_extbb)(const void *thing) {
50 return _is_ir_extbb(thing);
54 * allocate a new extended block header.
56 static void allocate_extblk(ir_node *block, env_t *env) {
57 ir_extblk *extblk = obstack_alloc(env->obst, sizeof(*extblk));
59 extblk->kind = k_ir_extblk;
61 extblk->blks = (ir_node **)env->head;
65 set_Block_extbb(block, extblk);
66 set_irn_link(block, NULL);
70 * Returns the number of block successors.
71 * we are interested only in 1, 2 and >2.
73 static int get_block_n_succs(ir_node *block) {
74 if (edges_activated(current_ir_graph)) {
75 const ir_edge_t *edge;
77 edge = get_block_succ_first(block);
80 edge = get_block_succ_next(block, edge);
83 edge = get_block_succ_next(block, edge);
86 return get_Block_n_cfg_outs(block);
90 * Pre block-walker. Calculates the extended block info.
92 static void pre_walk_calc_extbb(ir_node *block, void *ctx) {
93 int n = get_Block_n_cfgpreds(block);
96 if (n <= 0 || n > 1 || block == env->start_block) {
98 * block is a JOIN-node ie the control flow from
99 * many other blocks joins here. block is a leader.
100 * Note that we handle unreachable blocks (n <= 0) here too.
102 allocate_extblk(block, env);
104 else { /* we have only one control flow predecessor */
105 ir_node *add_to = get_Block_cfgpred_block(block, 0);
107 /* blocks with only one BAD predecessors are leaders too */
108 if (is_Bad(add_to)) {
109 allocate_extblk(block, env);
112 * Only one control flow predecessor. This block belongs
113 * to the same extended basic block as its predecessor.
115 ir_node *cf_op = skip_Proj(get_Block_cfgpred(block, 0));
117 if (!irn_visited_else_mark(cf_op)) {
118 ir_node *pred_bl = get_nodes_block(cf_op);
119 if (get_block_n_succs(pred_bl) > 2) {
120 /* More than two successors means we have a jump table.
121 * we cannot include a jump target into the current extended
122 * basic block, so create a new one here.
124 allocate_extblk(block, env);
126 /* either the previous block has only one successor or
127 * this is the first successor after an if, include it.
129 set_Block_extbb(block, NULL);
132 /* already marked, so begin a new extended block here */
133 allocate_extblk(block, env);
139 /** A special extended block used as sentinel */
140 static ir_extblk _sentinel = { k_ir_extblk, 0xFEA1DEAD, NULL, NULL };
143 * Post block-walker. Calculates the extended block info.
144 * During construction, we use the (free) block input of all basic blocks
145 * to point to there previous block.
147 static void post_walk_calc_extbb(ir_node *block, void *ctx)
149 ir_extblk *extbb = get_Block_extbb(block);
151 ir_extblk *sentinel = &_sentinel;
154 ir_node *curr, *prev, *list;
157 * Search the leader. It can happen, that we fall into an endless
158 * loop, because we enter an unreachable loop that is not yet detected.
159 * We break the loop using a sentinel.
161 for (curr = block; !extbb; curr = prev) {
162 prev = get_Block_cfgpred_block(curr, 0);
163 extbb = get_Block_extbb(prev);
164 set_Block_extbb(curr, sentinel);
167 if (extbb == sentinel) {
168 /* We detect a dead loop. We fix this by allocating a
169 * special Extended block
171 ir_printf("Dead loop detected starting with %+F::%+F\n", get_irg_entity(current_ir_graph), block);
173 allocate_extblk(block, env);
174 extbb = get_Block_extbb(block);
175 set_Block_extbb(block, sentinel);
178 /* replace all sentinels by the extbb info */
182 if (get_Block_extbb(prev) != sentinel)
184 set_irn_link(prev, list);
186 prev = get_Block_cfgpred_block(prev, 0);
188 /* arg, the list is in wrong order, turn around and add to the extbb list */
189 for (curr = list; curr; curr = prev) {
190 prev = get_irn_link(curr);
191 set_irn_link(curr, extbb->link);
193 set_Block_extbb(curr, extbb);
200 * Compute the extended basic blocks for a graph
202 void compute_extbb(ir_graph *irg) {
204 ir_extblk *extbb, *next;
207 obstack_free(irg->extbb_obst, NULL);
209 irg->extbb_obst = XMALLOC(struct obstack);
210 obstack_init(irg->extbb_obst);
212 env.obst = irg->extbb_obst;
214 env.start_block = get_irg_start_block(irg);
216 if (! edges_activated(irg)) {
217 /* we don't have edges */
218 assure_irg_outs(irg);
221 /* we must mark nodes, so increase the visited flag */
222 inc_irg_visited(irg);
223 irg_block_walk_graph(irg, pre_walk_calc_extbb, post_walk_calc_extbb, &env);
226 * Ok, we have now the list of all extended blocks starting with env.head
227 * every extended block "knowns" the number of blocks in visited and
228 * the blocks are linked in link.
229 * Now we can create arrays that hold the blocks, some kind of "out" edges
230 * for the extended block
232 for (extbb = env.head; extbb; extbb = next) {
233 int i, len = (int)extbb->visited;
236 next = (ir_extblk *)extbb->blks;
238 extbb->blks = NEW_ARR_D(ir_node *, env.obst, len);
240 for (block = extbb->link, i = 0; i < len; ++i) {
241 ir_node *nblock = get_irn_link(block);
243 /* ensure that the leader is the first one */
244 extbb->blks[len - 1 - i] = block;
245 set_irn_link(block, NULL);
251 for (i = len - 1; i > 0; --i) {
252 ir_node *blk = extbb->blks[i];
254 if (get_Block_n_cfgpreds(blk) != 1) {
255 assert(!"Block for more than one predecessors is no leader");
256 } else if (get_Block_cfgpred_block(blk, 0) != extbb->blks[i - 1]) {
257 assert(!"extbb block order wrong");
266 irg->extblk_state = extblk_valid;
269 /* free all extended block info. */
270 void free_extbb(ir_graph *irg) {
271 if (irg->extbb_obst) {
272 obstack_free(irg->extbb_obst, NULL);
273 xfree(irg->extbb_obst);
274 irg->extbb_obst = NULL;
276 irg->extblk_state = extblk_none;
279 /* Return the extended block of a node. */
280 ir_extblk *get_nodes_extbb(ir_node *node) {
281 ir_node *block = is_Block(node) ? node : get_irn_n(node, -1);
282 return get_Block_extbb(block);
285 /* Gets the visited counter of an extended block. */
286 ir_visited_t (get_extbb_visited)(const ir_extblk *blk) {
287 return _get_extbb_visited(blk);
290 /* Sets the visited counter of an extended block. */
291 void (set_extbb_visited)(ir_extblk *blk, ir_visited_t visited) {
292 _set_extbb_visited(blk, visited);
295 /* Mark an extended block as visited in a graph. */
296 void (mark_extbb_visited)(ir_extblk *blk) {
297 _mark_extbb_visited(blk);
300 /* Returns non-zero if an extended was visited. */
301 int (extbb_visited)(const ir_extblk *blk) {
302 return _extbb_visited(blk);
305 /* Returns non-zero if an extended block was NOT visited. */
306 int (extbb_not_visited)(const ir_extblk *blk) {
307 return _extbb_not_visited(blk);
310 /* Returns the link field of an extended block. */
311 void *(get_extbb_link)(const ir_extblk *blk) {
312 return _get_extbb_link(blk);
315 /* Sets the link field of an extended block. */
316 void (set_extbb_link)(ir_extblk *blk, void *link) {
317 _set_extbb_link(blk, link);
320 /* Return the number of basic blocks of an extended block */
321 int (get_extbb_n_blocks)(const ir_extblk *blk) {
322 return _get_extbb_n_blocks(blk);
325 /* Return the i'th basic block of an extended block */
326 ir_node *(get_extbb_block)(ir_extblk *blk, int pos) {
327 return _get_extbb_block(blk, pos);
330 /* Return the leader basis block of an extended block. */
331 ir_node *(get_extbb_leader)(ir_extblk *blk) {
332 return _get_extbb_leader(blk);
335 /* Return the node number of an extended block. */
336 long get_extbb_node_nr(ir_extblk *blk) {
337 return get_irn_node_nr(get_extbb_leader(blk));
340 static void irg_extblock_walk_2(ir_extblk *blk, extbb_walk_func *pre, extbb_walk_func *post, void *env) {
344 if (extbb_not_visited(blk)) {
345 mark_extbb_visited(blk);
347 if (pre) pre(blk, env);
349 node = get_extbb_leader(blk);
350 for (i = get_Block_n_cfgpreds(node) - 1; i >= 0; --i) {
351 /* find the corresponding predecessor block. */
352 ir_node *pred = get_Block_cfgpred_block(node, i);
353 if (is_Block(pred)) {
355 irg_extblock_walk_2(get_Block_extbb(pred), pre, post, env);
358 assert(is_Bad(pred));
362 if (post) post(blk, env);
366 /* walks only over extended Block nodes in the graph. Has it's own visited
367 flag, so that it can be interleaved with the other walker. */
368 void irg_extblock_walk(ir_extblk *blk, extbb_walk_func *pre, extbb_walk_func *post, void *env) {
369 ir_node *pred, *start_bl = get_irg_start_block(current_ir_graph);
370 ir_extblk *start_blk = get_Block_extbb(start_bl);
374 inc_irg_block_visited(current_ir_graph);
376 /* assure the start block is the first one */
377 mark_extbb_visited(start_blk);
379 post(start_blk, env);
380 irg_extblock_walk_2(blk, pre, post, env);
382 /* keepalive: the endless loops ... */
383 if (blk == get_Block_extbb(get_irg_end_block(current_ir_graph))) {
384 ir_node *node = get_irg_end(current_ir_graph);
385 int arity = get_irn_arity(node);
386 for (i = 0; i < arity; i++) {
387 pred = get_irn_n(node, i);
389 irg_extblock_walk_2(get_Block_extbb(pred), pre, post, env);
390 else if (is_Phi(pred)) {
391 /* Sometimes the blocks died, but are still reachable through Phis.
392 * Make sure the algorithms that try to remove these reach them. */
393 ir_node *block = get_nodes_block(pred);
396 irg_extblock_walk_2(get_Block_extbb(block), pre, post, env);
405 /* Walks only over reachable Extended Basic Block nodes in the graph. */
406 void irg_extblock_walk_graph(ir_graph *irg, extbb_walk_func *pre, extbb_walk_func *post, void *env) {
407 ir_node *endbl = get_irg_end_block(irg);
408 ir_extblk *blk = get_Block_extbb(endbl);
409 ir_graph *rem = current_ir_graph;
410 current_ir_graph = irg;
411 irg_extblock_walk(blk, pre, post, env);
412 current_ir_graph = rem;