3 * File name: ir/ana/irextbb.c
4 * Purpose: Extended basis block support.
9 * Copyright: (c) 2002-2005 Universität Karlsruhe
10 * Licence: This file protected by GPL - GNU GENERAL PUBLIC LICENSE.
16 * Computes extended basic blocks.
18 * @author Michael Beck
20 #include "irextbb_t.h"
23 #include "irgraph_t.h"
24 #include "iredges_t.h"
30 struct obstack *obst; /**< the obstack where allocations took place */
31 ir_extblk *head; /**< head of the list of all extended blocks */
32 ir_node *start_block; /**< the start block of the current graph */
35 int (is_ir_extbb)(const void *thing) {
36 return _is_ir_extbb(thing);
40 * allocate a new extended block header.
42 static void allocate_extblk(ir_node *block, env_t *env)
44 ir_extblk *extblk = obstack_alloc(env->obst, sizeof(*extblk));
46 extblk->kind = k_ir_extblk;
48 extblk->blks = (ir_node **)env->head;
52 set_Block_extbb(block, extblk);
53 set_irn_link(block, NULL);
57 * Returns the number of block successors.
58 * we are interested only in 1, 2 and >2.
60 static int get_block_n_succs(ir_node *block) {
61 if (edges_activated(current_ir_graph)) {
62 const ir_edge_t *edge;
64 edge = get_block_succ_first(block);
67 edge = get_block_succ_next(block, edge);
70 edge = get_block_succ_next(block, edge);
73 return get_Block_n_cfg_outs(block);
77 * Pre block-walker. Calculates the extended block info.
79 static void pre_walk_calc_extbb(ir_node *block, void *ctx)
81 int n = get_Block_n_cfgpreds(block);
84 if (n <= 0 || n > 1 || block == env->start_block) {
86 * block is a JOIN-node ie the control flow from
87 * many other blocks joins here. block is a leader.
88 * Note that we handle unreachable blocks (n <= 0) here too.
90 allocate_extblk(block, env);
92 else { /* we have only one control flow predecessor */
93 ir_node *add_to = get_Block_cfgpred_block(block, 0);
95 /* blocks with only one BAD predecessors are leaders too */
97 allocate_extblk(block, env);
100 * Only one control flow predecessor. This block belongs
101 * to the same extended basic block as its predecessor.
103 ir_node *cf_op = skip_Proj(get_Block_cfgpred(block, 0));
105 if (irn_not_visited(cf_op)) {
106 ir_node *pred_bl = get_nodes_block(cf_op);
107 if (get_block_n_succs(pred_bl) > 2) {
108 /* More than two successors means we have a jump table.
109 * we cannot include a jump target into the current extended
110 * basic block, so create a new one here.
112 allocate_extblk(block, env);
114 /* either the previous block has only one successor or
115 * this is the first successor after an if, include it.
117 set_Block_extbb(block, NULL);
119 mark_irn_visited(cf_op);
121 /* already marked, so begin a new extended block here */
122 allocate_extblk(block, env);
128 /** A special extended block used as sentinel */
129 static ir_extblk _sentinel = { k_ir_extblk, 0xFEA1DEAD };
132 * Post block-walker. Calculates the extended block info.
133 * During construction, we use the (free) block input of all basic blocks
134 * to point to there previous block.
136 static void post_walk_calc_extbb(ir_node *block, void *ctx)
138 ir_extblk *extbb = get_Block_extbb(block);
140 ir_extblk *sentinel = &_sentinel;
143 ir_node *curr, *prev, *list;
146 * Search the leader. It can happen, that we fall into an endless
147 * loop, because we enter an unreachable loop that is not yet detected.
148 * We break the loop using a sentinel.
150 for (curr = block; !extbb; curr = prev) {
151 prev = get_Block_cfgpred_block(curr, 0);
152 extbb = get_Block_extbb(prev);
153 set_Block_extbb(curr, sentinel);
156 if (extbb == sentinel) {
157 /* We detect a dead loop. We fix this by allocating a
158 * special Extended block
160 ir_printf("Dead loop detected starting with %+F::%+F\n", get_irg_entity(current_ir_graph), block);
162 allocate_extblk(block, env);
163 extbb = get_Block_extbb(block);
164 set_Block_extbb(block, sentinel);
167 /* replace all sentinels by the extbb info */
171 if (get_Block_extbb(prev) != sentinel)
173 set_irn_link(prev, list);
175 prev = get_Block_cfgpred_block(prev, 0);
177 /* arg, the list is in wrong order, turn around and add to the extbb list */
178 for (curr = list; curr; curr = prev) {
179 prev = get_irn_link(curr);
180 set_irn_link(curr, extbb->link);
182 set_Block_extbb(curr, extbb);
189 * Compute the extended basic blocks for a graph
191 void compute_extbb(ir_graph *irg) {
193 ir_extblk *extbb, *next;
196 obstack_free(irg->extbb_obst, NULL);
198 irg->extbb_obst = xmalloc(sizeof(*irg->extbb_obst));
200 obstack_init(irg->extbb_obst);
202 env.obst = irg->extbb_obst;
204 env.start_block = get_irg_start_block(irg);
206 if (! edges_activated(irg)) {
207 /* we don't have edges */
208 assure_irg_outs(irg);
211 /* we must mark nodes, so increase the visited flag */
212 inc_irg_visited(irg);
213 irg_block_walk_graph(irg, pre_walk_calc_extbb, post_walk_calc_extbb, &env);
216 * Ok, we have now the list of all extended blocks starting with env.head
217 * every extended block "knowns" the number of blocks in visited and
218 * the blocks are linked in link.
219 * Now we can create arrays that hold the blocks, some kind of "out" edges
220 * for the extended block
222 for (extbb = env.head; extbb; extbb = next) {
223 int i, len = (int)extbb->visited;
226 next = (ir_extblk *)extbb->blks;
228 extbb->blks = NEW_ARR_D(ir_node *, env.obst, len);
230 for (block = extbb->link, i = 0; i < len; ++i) {
231 ir_node *nblock = get_irn_link(block);
233 /* ensure that the leader is the first one */
234 extbb->blks[len - 1 - i] = block;
235 set_irn_link(block, NULL);
241 for (i = len - 1; i > 0; --i) {
242 ir_node *blk = extbb->blks[i];
244 if (get_Block_n_cfgpreds(blk) != 1) {
245 assert(!"Block for more than one predecessors is no leader");
246 } else if (get_Block_cfgpred_block(blk, 0) != extbb->blks[i - 1]) {
247 assert(!"extbb block order wrong");
256 irg->extblk_state = extblk_valid;
259 /* free all extended block info. */
260 void free_extbb(ir_graph *irg) {
261 if (irg->extbb_obst) {
262 obstack_free(irg->extbb_obst, NULL);
263 xfree(irg->extbb_obst);
264 irg->extbb_obst = NULL;
266 irg->extblk_state = extblk_none;
269 /* Return the extended block of a node. */
270 ir_extblk *get_nodes_extbb(ir_node *node) {
271 ir_node *block = is_Block(node) ? node : get_irn_n(node, -1);
272 return get_Block_extbb(block);
275 /* Gets the visited counter of an extended block. */
276 unsigned long (get_extbb_visited)(const ir_extblk *blk) {
277 return _get_extbb_visited(blk);
280 /* Sets the visited counter of an extended block. */
281 void (set_extbb_visited)(ir_extblk *blk, unsigned long visited) {
282 _set_extbb_visited(blk, visited);
285 /* Mark an extended block as visited in a graph. */
286 void (mark_extbb_visited)(ir_extblk *blk) {
287 _mark_extbb_visited(blk);
290 /* Returns non-zero if an extended was visited. */
291 int (extbb_visited)(const ir_extblk *blk) {
292 return _extbb_visited(blk);
295 /* Returns non-zero if an extended block was NOT visited. */
296 int (extbb_not_visited)(const ir_extblk *blk) {
297 return _extbb_not_visited(blk);
300 /* Returns the link field of an extended block. */
301 void *(get_extbb_link)(const ir_extblk *blk) {
302 return _get_extbb_link(blk);
305 /* Sets the link field of an extended block. */
306 void (set_extbb_link)(ir_extblk *blk, void *link) {
307 _set_extbb_link(blk, link);
310 /* Return the number of basic blocks of an extended block */
311 int (get_extbb_n_blocks)(const ir_extblk *blk) {
312 return _get_extbb_n_blocks(blk);
315 /* Return the i'th basic block of an extended block */
316 ir_node *(get_extbb_block)(ir_extblk *blk, int pos) {
317 return _get_extbb_block(blk, pos);
320 /* Return the leader basis block of an extended block. */
321 ir_node *(get_extbb_leader)(ir_extblk *blk) {
322 return _get_extbb_leader(blk);
325 /* Return the node number of an extended block. */
326 long get_extbb_node_nr(ir_extblk *blk) {
327 return get_irn_node_nr(get_extbb_leader(blk));
330 static void irg_extblock_walk_2(ir_extblk *blk, extbb_walk_func *pre, extbb_walk_func *post, void *env)
335 if (extbb_not_visited(blk)) {
336 mark_extbb_visited(blk);
338 if (pre) pre(blk, env);
340 node = get_extbb_leader(blk);
341 for (i = get_Block_n_cfgpreds(node) - 1; i >= 0; --i) {
342 /* find the corresponding predecessor block. */
343 ir_node *pred = get_Block_cfgpred_block(node, i);
344 if (is_Block(pred)) {
346 irg_extblock_walk_2(get_Block_extbb(pred), pre, post, env);
349 assert(is_Bad(pred));
353 if (post) post(blk, env);
357 /* walks only over extended Block nodes in the graph. Has it's own visited
358 flag, so that it can be interleaved with the other walker. */
359 void irg_extblock_walk(ir_extblk *blk, extbb_walk_func *pre, extbb_walk_func *post, void *env)
361 ir_node *pred, *start_bl = get_irg_start_block(current_ir_graph);
362 ir_extblk *start_blk = get_Block_extbb(start_bl);
366 assert(!get_interprocedural_view()); /* interprocedural_view not implemented */
367 inc_irg_block_visited(current_ir_graph);
369 /* assure the start block is the first one */
370 mark_extbb_visited(start_blk);
372 post(start_blk, env);
373 irg_extblock_walk_2(blk, pre, post, env);
375 /* keepalive: the endless loops ... */
376 if (blk == get_Block_extbb(get_irg_end_block(current_ir_graph))) {
377 ir_node *node = get_irg_end(current_ir_graph);
378 int arity = get_irn_arity(node);
379 for (i = 0; i < arity; i++) {
380 pred = get_irn_n(node, i);
382 irg_extblock_walk_2(get_Block_extbb(pred), pre, post, env);
383 else if (is_Phi(pred)) {
384 /* Sometimes the blocks died, but are still reachable through Phis.
385 * Make sure the algorithms that try to remove these reach them. */
386 ir_node *block = get_nodes_block(pred);
389 irg_extblock_walk_2(get_Block_extbb(block), pre, post, env);
398 /* Walks only over reachable Extended Basic Block nodes in the graph. */
399 void irg_extblock_walk_graph(ir_graph *irg, extbb_walk_func *pre, extbb_walk_func *post, void *env)
401 ir_node *endbl = get_irg_end_block(irg);
402 ir_extblk *blk = get_Block_extbb(endbl);
403 ir_graph *rem = current_ir_graph;
404 current_ir_graph = irg;
405 irg_extblock_walk(blk, pre, post, env);
406 current_ir_graph = rem;