nsz Git - libfirm/blob - ir/ana/irextbb.c

   1 /*
   2  * Copyright (C) 1995-2008 University of Karlsruhe.  All right reserved.
   3  *
   4  * This file is part of libFirm.
   5  *
   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.
  10  *
  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.
  14  *
  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
  17  * PURPOSE.
  18  */
  19
  20 /**
  21  * @file
  22  * @brief    Extended basis block support.
  23  * @author   Michael Beck
  24  * @date     5.2005
  25  */
  26 #include "config.h"
  27
  28 #include "irextbb_t.h"
  29 #include "irgwalk.h"
  30 #include "irnode_t.h"
  31 #include "irgraph_t.h"
  32 #include "iredges_t.h"
  33 #include "irouts.h"
  34 #include "xmalloc.h"
  35 #include "irprintf.h"
  36
  37 /**
  38  * Environment for extbb construction.
  39  */
  40 typedef struct env {
  41         struct obstack *obst;   /**< the obstack where allocations took place */
  42         ir_extblk *head;        /**< head of the list of all extended blocks */
  43         ir_node *start_block;   /**< the start block of the current graph */
  44 } env_t;
  45
  46 int (is_ir_extbb)(const void *thing)
  47 {
  48         return _is_ir_extbb(thing);
  49 }
  50
  51 /**
  52  * allocate a new extended block header.
  53  */
  54 static void allocate_extblk(ir_node *block, env_t *env)
  55 {
  56         ir_extblk *extblk = OALLOC(env->obst, ir_extblk);
  57
  58         extblk->kind    = k_ir_extblk;
  59         extblk->visited = 1;
  60         extblk->blks    = (ir_node **)env->head;
  61         extblk->link    = block;
  62         env->head       = extblk;
  63
  64         set_Block_extbb(block, extblk);
  65         set_irn_link(block, NULL);
  66 }
  67
  68 /**
  69  * Returns the number of block successors.
  70  * we are interested only in 1, 2 and >2.
  71  */
  72 static int get_block_n_succs(ir_node *block)
  73 {
  74         if (edges_activated(current_ir_graph)) {
  75                 const ir_edge_t *edge;
  76
  77                 edge = get_block_succ_first(block);
  78                 if (! edge)
  79                         return 0;
  80                 edge = get_block_succ_next(block, edge);
  81                 if (! edge)
  82                         return 1;
  83                 edge = get_block_succ_next(block, edge);
  84                 return edge ? 3 : 2;
  85         }
  86         return get_Block_n_cfg_outs(block);
  87 }
  88
  89 /**
  90  * Pre block-walker. Calculates the extended block info.
  91  */
  92 static void pre_walk_calc_extbb(ir_node *block, void *ctx)
  93 {
  94         int n = get_Block_n_cfgpreds(block);
  95         env_t *env = (env_t*) ctx;
  96
  97         if (n <= 0 || n > 1 || block == env->start_block) {
  98                 /*
  99                  * block is a JOIN-node ie the control flow from
 100                  * many other blocks joins here. block is a leader.
 101                  * Note that we handle unreachable blocks (n <= 0) here too.
 102                  */
 103                 allocate_extblk(block, env);
 104         }
 105         else {    /* we have only one control flow predecessor */
 106                 ir_node *add_to = get_Block_cfgpred_block(block, 0);
 107
 108                 /* blocks with only one BAD predecessors are leaders too */
 109                 if (is_Bad(add_to)) {
 110                         allocate_extblk(block, env);
 111                 } else {
 112                         /*
 113                          * Only one control flow predecessor. This block belongs
 114                          * to the same extended basic block as its predecessor.
 115                          */
 116                         ir_node *cf_op = skip_Proj(get_Block_cfgpred(block, 0));
 117
 118                         if (!irn_visited_else_mark(cf_op)) {
 119                                 ir_node *pred_bl = get_nodes_block(cf_op);
 120                                 if (get_block_n_succs(pred_bl) > 2) {
 121                                         /* More than two successors means we have a jump table.
 122                                          * we cannot include a jump target into the current extended
 123                                          * basic block, so create a new one here.
 124                                          */
 125                                         allocate_extblk(block, env);
 126                                 } else {
 127                                         /* either the previous block has only one successor or
 128                                          * this is the first successor after an if, include it.
 129                                          */
 130                                         set_Block_extbb(block, NULL);
 131                                 }
 132                         } else {
 133                                 /* already marked, so begin a new extended block here */
 134                                 allocate_extblk(block, env);
 135                         }
 136                 }
 137         }
 138 }
 139
 140 /** A special extended block used as sentinel */
 141 static ir_extblk _sentinel = { k_ir_extblk, 0xFEA1DEAD, NULL, NULL };
 142
 143 /**
 144  * Post block-walker. Calculates the extended block info.
 145  * During construction, we use the (free) block input of all basic blocks
 146  * to point to their previous block.
 147  */
 148 static void post_walk_calc_extbb(ir_node *block, void *ctx)
 149 {
 150         ir_extblk *extbb = get_Block_extbb(block);
 151         env_t *env = (env_t*) ctx;
 152         ir_extblk *sentinel = &_sentinel;
 153
 154         if (! extbb) {
 155                 ir_node *curr, *prev, *list;
 156
 157                 /*
 158                  * Search the leader. It can happen, that we fall into an endless
 159                  * loop, because we enter an unreachable loop that is not yet detected.
 160                  * We break the loop using a sentinel.
 161                  */
 162                 for (curr = block; !extbb; curr = prev) {
 163                         prev = get_Block_cfgpred_block(curr, 0);
 164                         extbb = get_Block_extbb(prev);
 165                         set_Block_extbb(curr, sentinel);
 166                 }
 167
 168                 if (extbb == sentinel) {
 169                         /* We detect a dead loop. We fix this by allocating a
 170                          * special Extended block
 171                          */
 172                         ir_printf("Dead loop detected starting with %+F::%+F\n", get_irg_entity(current_ir_graph), block);
 173
 174                         allocate_extblk(block, env);
 175                         extbb = get_Block_extbb(block);
 176                         set_Block_extbb(block, sentinel);
 177                 }
 178
 179                 /* replace all sentinels by the extbb info */
 180                 prev = block;
 181                 list = NULL;
 182                 for (;;) {
 183                         if (get_Block_extbb(prev) != sentinel)
 184                                 break;
 185                         set_irn_link(prev, list);
 186                         list = prev;
 187                         prev = get_Block_cfgpred_block(prev, 0);
 188                 }
 189                 /* arg, the list is in wrong order, turn around and add to the extbb list */
 190                 for (curr = list; curr; curr = prev) {
 191                         prev = (ir_node*) get_irn_link(curr);
 192                         set_irn_link(curr, extbb->link);
 193                         extbb->link = curr;
 194                         set_Block_extbb(curr, extbb);
 195                         ++extbb->visited;
 196                 }
 197         }
 198 }
 199
 200 void compute_extbb(ir_graph *irg)
 201 {
 202         env_t env;
 203         ir_extblk *extbb, *next;
 204
 205         if (irg->extbb_obst)
 206                 obstack_free(irg->extbb_obst, NULL);
 207         else
 208                 irg->extbb_obst = XMALLOC(struct obstack);
 209         obstack_init(irg->extbb_obst);
 210
 211         env.obst        = irg->extbb_obst;
 212         env.head        = NULL;
 213         env.start_block = get_irg_start_block(irg);
 214
 215         if (! edges_activated(irg)) {
 216                 /* we don't have edges */
 217                 assure_irg_outs(irg);
 218         }
 219
 220         /* we must mark nodes, so increase the visited flag */
 221         inc_irg_visited(irg);
 222         irg_block_walk_graph(irg, pre_walk_calc_extbb, post_walk_calc_extbb, &env);
 223
 224         /*
 225          * Ok, we have now the list of all extended blocks starting with env.head
 226          * every extended block "knowns" the number of blocks in visited and
 227          * the blocks are linked in link.
 228          * Now we can create arrays that hold the blocks, some kind of "out" edges
 229          * for the extended block
 230          */
 231         for (extbb = env.head; extbb; extbb = next) {
 232                 int i, len = (int)extbb->visited;
 233                 ir_node *block;
 234
 235                 next = (ir_extblk *)extbb->blks;
 236
 237                 extbb->blks = NEW_ARR_D(ir_node *, env.obst, len);
 238
 239                 for (block = (ir_node*) extbb->link, i = 0; i < len; ++i) {
 240                         ir_node *nblock = (ir_node*) get_irn_link(block);
 241
 242                         /* ensure that the leader is the first one */
 243                         extbb->blks[len - 1 - i] = block;
 244                         set_irn_link(block, NULL);
 245                         block = nblock;
 246                 }
 247
 248 #ifndef NDEBUG
 249                 /* check it */
 250                 for (i = len - 1; i > 0; --i) {
 251                         ir_node *blk = extbb->blks[i];
 252
 253                         if (get_Block_n_cfgpreds(blk) != 1) {
 254                                 assert(!"Block for more than one predecessors is no leader");
 255                         } else if (get_Block_cfgpred_block(blk, 0) != extbb->blks[i - 1]) {
 256                                 assert(!"extbb block order wrong");
 257                         }
 258                 }
 259 #endif
 260
 261                 extbb->link    = NULL;
 262                 extbb->visited = 0;
 263         }
 264
 265         set_irg_state(irg, IR_GRAPH_STATE_VALID_EXTENDED_BLOCKS);
 266 }
 267
 268 void free_extbb(ir_graph *irg)
 269 {
 270         if (irg->extbb_obst) {
 271                 obstack_free(irg->extbb_obst, NULL);
 272                 xfree(irg->extbb_obst);
 273                 irg->extbb_obst = NULL;
 274         }
 275         clear_irg_state(irg, IR_GRAPH_STATE_VALID_EXTENDED_BLOCKS);
 276 }
 277
 278 ir_extblk *get_nodes_extbb(const ir_node *node)
 279 {
 280         const ir_node *block = is_Block(node) ? node : get_nodes_block(node);
 281         return get_Block_extbb(block);
 282 }
 283
 284 ir_visited_t (get_extbb_visited)(const ir_extblk *blk)
 285 {
 286         return _get_extbb_visited(blk);
 287 }
 288
 289 void (set_extbb_visited)(ir_extblk *blk, ir_visited_t visited)
 290 {
 291         _set_extbb_visited(blk, visited);
 292 }
 293
 294 void (mark_extbb_visited)(ir_extblk *blk)
 295 {
 296         _mark_extbb_visited(blk);
 297 }
 298
 299 int (extbb_visited)(const ir_extblk *blk)
 300 {
 301         return _extbb_visited(blk);
 302 }
 303
 304 int (extbb_not_visited)(const ir_extblk *blk)
 305 {
 306         return _extbb_not_visited(blk);
 307 }
 308
 309 void *(get_extbb_link)(const ir_extblk *blk)
 310 {
 311         return _get_extbb_link(blk);
 312 }
 313
 314 void (set_extbb_link)(ir_extblk *blk, void *link)
 315 {
 316         _set_extbb_link(blk, link);
 317 }
 318
 319 int (get_extbb_n_blocks)(const ir_extblk *blk)
 320 {
 321         return _get_extbb_n_blocks(blk);
 322 }
 323
 324 ir_node *(get_extbb_block)(const ir_extblk *blk, int pos)
 325 {
 326         return _get_extbb_block(blk, pos);
 327 }
 328
 329 ir_node *(get_extbb_leader)(const ir_extblk *blk)
 330 {
 331         return _get_extbb_leader(blk);
 332 }
 333
 334 long get_extbb_node_nr(const ir_extblk *blk)
 335 {
 336         return get_irn_node_nr(get_extbb_leader(blk));
 337 }
 338
 339 static void irg_extblock_walk_2(ir_extblk *blk, extbb_walk_func *pre, extbb_walk_func *post, void *env)
 340 {
 341         int i;
 342         ir_node *node;
 343
 344         if (extbb_not_visited(blk)) {
 345                 mark_extbb_visited(blk);
 346
 347                 if (pre) pre(blk, env);
 348
 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)) {
 354                                 /* recursion */
 355                                 irg_extblock_walk_2(get_Block_extbb(pred), pre, post, env);
 356                         }
 357                         else {
 358                                 assert(is_Bad(pred));
 359                         }
 360                 }
 361
 362                 if (post) post(blk, env);
 363         }
 364 }
 365
 366 void irg_extblock_walk(ir_extblk *blk, extbb_walk_func *pre, extbb_walk_func *post, void *env)
 367 {
 368         ir_node *pred, *start_bl = get_irg_start_block(current_ir_graph);
 369         ir_extblk *start_blk = get_Block_extbb(start_bl);
 370         int i;
 371
 372         assert(blk);
 373         inc_irg_block_visited(current_ir_graph);
 374
 375         /* assure the start block is the first one */
 376         mark_extbb_visited(start_blk);
 377         if (post)
 378                 post(start_blk, env);
 379         irg_extblock_walk_2(blk, pre, post, env);
 380
 381         /* keepalive: the endless loops ... */
 382         if (blk == get_Block_extbb(get_irg_end_block(current_ir_graph))) {
 383                 ir_node *node = get_irg_end(current_ir_graph);
 384                 int arity = get_irn_arity(node);
 385                 for (i = 0; i < arity; i++) {
 386                         pred = get_irn_n(node, i);
 387                         if (is_Block(pred))
 388                                 irg_extblock_walk_2(get_Block_extbb(pred), pre, post, env);
 389                         else if (is_Phi(pred)) {
 390                                 /* Sometimes the blocks died, but are still reachable through Phis.
 391                                  * Make sure the algorithms that try to remove these reach them. */
 392                                 ir_node *block = get_nodes_block(pred);
 393
 394                                 if (! is_Bad(block))
 395                                         irg_extblock_walk_2(get_Block_extbb(block), pre, post, env);
 396                         }
 397                 }
 398         }
 399
 400         if (pre)
 401                 pre(start_blk, env);
 402 }
 403
 404 void irg_extblock_walk_graph(ir_graph *irg, extbb_walk_func *pre, extbb_walk_func *post, void *env)
 405 {
 406         ir_node *endbl = get_irg_end_block(irg);
 407         ir_extblk *blk = get_Block_extbb(endbl);
 408         ir_graph *rem  = current_ir_graph;
 409         current_ir_graph = irg;
 410         irg_extblock_walk(blk, pre, post, env);
 411         current_ir_graph = rem;
 412 }