nsz Git - libfirm/blob - ir/opt/ifconv.c

   1 /*
   2  * Copyright (C) 1995-2007 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    ir/opt/ifconv.c
  22  * @brief   If conversion
  23  * @author  Christoph Mallon
  24  * @version $Id$
  25  */
  26
  27 #ifdef HAVE_CONFIG_H
  28 #include "config.h"
  29 #endif
  30
  31 #include <assert.h>
  32 #include "iroptimize.h"
  33 #include "obst.h"
  34 #include "irnode_t.h"
  35 #include "cdep.h"
  36 #include "ircons.h"
  37 #include "irdom.h"
  38 #include "irgmod.h"
  39 #include "irgopt.h"
  40 #include "irgwalk.h"
  41 #include "irtools.h"
  42 #include "array.h"
  43 #include "xmalloc.h"
  44
  45 // debug
  46 #include "irdump.h"
  47 #include "debug.h"
  48
  49 DEBUG_ONLY(static firm_dbg_module_t *dbg);
  50
  51 /** allow every Psi to be created. */
  52 static int default_allow_ifconv(ir_node *sel, ir_node* phi_list, int i, int j)
  53 {
  54         (void) sel;
  55         (void) phi_list;
  56         (void) i;
  57         (void) j;
  58         return 1;
  59 }
  60
  61 /**
  62  * Default options.
  63  */
  64 static const ir_settings_if_conv_t default_info = {
  65         0,    /* doesn't matter for Psi */
  66         default_allow_ifconv
  67 };
  68
  69 /**
  70  * Additional block info.
  71  */
  72 typedef struct block_info {
  73         ir_node *phi;   /**< head of the Phi list */
  74         int has_pinned; /**< set if the block contains instructions that cannot be moved */
  75 } block_info;
  76
  77
  78 static INLINE block_info* get_block_blockinfo(const ir_node* block)
  79 {
  80         return get_irn_link(block);
  81 }
  82
  83
  84 /**
  85  * Returns non-zero if a Block can be emptied.
  86  */
  87 static int can_empty_block(ir_node *block)
  88 {
  89         return !get_block_blockinfo(block)->has_pinned;
  90 }
  91
  92
  93 static ir_node* walk_to_projx(ir_node* start, const ir_node* dependency)
  94 {
  95         int arity;
  96         int i;
  97
  98         /* No need to find the conditional block if this block cannot be emptied and
  99          * therefore not moved */
 100         if (!can_empty_block(start)) return NULL;
 101
 102         arity = get_irn_arity(start);
 103         for (i = 0; i < arity; ++i) {
 104                 ir_node* pred = get_irn_n(start, i);
 105                 ir_node* pred_block = get_nodes_block(pred);
 106
 107                 if (pred_block == dependency) {
 108                         if (is_Proj(pred)) {
 109                                 assert(get_irn_mode(pred) == mode_X);
 110                                 return pred;
 111                         }
 112                         return NULL;
 113                 }
 114
 115                 if (is_Proj(pred)) {
 116                         assert(get_irn_mode(pred) == mode_X);
 117                         return NULL;
 118                 }
 119
 120                 if (is_cdep_on(pred_block, dependency)) {
 121                         return walk_to_projx(pred_block, dependency);
 122                 }
 123         }
 124         return NULL;
 125 }
 126
 127
 128 /**
 129  * Copies the DAG starting at node to the ith predecessor block of src_block
 130  * -if the node isn't in the src_block, this is a nop and the node is returned
 131  * -if the node is a phi in the src_block, the ith predecessor of the phi is
 132  *   returned
 133  * otherwise returns the copy of the passed node
 134  */
 135 static ir_node* copy_to(ir_node* node, ir_node* src_block, int i)
 136 {
 137         ir_node* dst_block;
 138         ir_node* copy;
 139         int arity;
 140         int j;
 141
 142         if (get_nodes_block(node) != src_block) return node;
 143         if (get_irn_op(node) == op_Phi) return get_irn_n(node, i);
 144
 145         copy = exact_copy(node);
 146         dst_block = get_nodes_block(get_irn_n(src_block, i));
 147         set_nodes_block(copy, dst_block);
 148
 149         DB((dbg, LEVEL_1, "Copying node %+F to block %+F, copy is %+F\n",
 150                 node, dst_block, copy));
 151
 152         arity = get_irn_arity(node);
 153         for (j = 0; j < arity; ++j) {
 154                 set_irn_n(copy, j, copy_to(get_irn_n(node, j), src_block, i));
 155                 DB((dbg, LEVEL_2, "-- pred %d is %+F\n", j, get_irn_n(copy, j)));
 156         }
 157         return copy;
 158 }
 159
 160
 161 /**
 162  * Remove predecessors i and j from node and add predecessor new_pred
 163  */
 164 static void rewire(ir_node* node, int i, int j, ir_node* new_pred)
 165 {
 166         int arity = get_irn_arity(node);
 167         ir_node **ins;
 168         int k;
 169         int l;
 170
 171         NEW_ARR_A(ir_node *, ins, arity - 1);
 172
 173         l = 0;
 174         for (k = 0; k < i;     ++k) ins[l++] = get_irn_n(node, k);
 175         for (++k;   k < j;     ++k) ins[l++] = get_irn_n(node, k);
 176         for (++k;   k < arity; ++k) ins[l++] = get_irn_n(node, k);
 177         ins[l++] = new_pred;
 178         assert(l == arity - 1);
 179         set_irn_in(node, l, ins);
 180 }
 181
 182
 183 /**
 184  * Remove the jth predecessors from the ith predecessor of block and add it to block
 185  */
 186 static void split_block(ir_node* block, int i, int j)
 187 {
 188         ir_node* pred_block = get_nodes_block(get_irn_n(block, i));
 189         int arity = get_irn_arity(block);
 190         int new_pred_arity;
 191         ir_node* phi;
 192         ir_node **ins;
 193         ir_node **pred_ins;
 194         int k;
 195
 196         DB((dbg, LEVEL_1, "Splitting predecessor %d of predecessor %d of %+F\n", j, i, block));
 197
 198         NEW_ARR_A(ir_node*, ins, arity + 1);
 199
 200         for (phi = get_block_blockinfo(block)->phi; phi != NULL; phi = get_irn_link(phi)) {
 201                 ir_node* copy = copy_to(get_irn_n(phi, i), pred_block, j);
 202
 203                 for (k = 0; k < i; ++k) ins[k] = get_irn_n(phi, k);
 204                 ins[k++] = copy;
 205                 for (; k < arity; ++k) ins[k] = get_irn_n(phi, k);
 206                 ins[k] = get_irn_n(phi, i);
 207                 assert(k == arity);
 208                 set_irn_in(phi, arity + 1, ins);
 209         }
 210
 211         for (k = 0; k < i; ++k) ins[k] = get_irn_n(block, k);
 212         ins[k++] = get_irn_n(pred_block, j);
 213         for (; k < arity; ++k) ins[k] = get_irn_n(block, k);
 214         ins[k] = get_irn_n(block, i);
 215         assert(k == arity);
 216         set_irn_in(block, arity + 1, ins);
 217
 218         new_pred_arity = get_irn_arity(pred_block) - 1;
 219         NEW_ARR_A(ir_node*, pred_ins, new_pred_arity);
 220
 221         for (phi = get_block_blockinfo(pred_block)->phi; phi != NULL; phi = get_irn_link(phi)) {
 222                 for (k = 0; k < j; ++k) pred_ins[k] = get_irn_n(phi, k);
 223                 for (; k < new_pred_arity; ++k) pred_ins[k] = get_irn_n(phi, k + 1);
 224                 assert(k == new_pred_arity);
 225                 if (new_pred_arity > 1) {
 226                         set_irn_in(phi, new_pred_arity, pred_ins);
 227                 } else {
 228                         exchange(phi, pred_ins[0]);
 229                 }
 230         }
 231
 232         for (k = 0; k < j; ++k) pred_ins[k] = get_irn_n(pred_block, k);
 233         for (; k < new_pred_arity; ++k) pred_ins[k] = get_irn_n(pred_block, k + 1);
 234         assert(k == new_pred_arity);
 235         if (new_pred_arity > 1) {
 236                 set_irn_in(pred_block, new_pred_arity, pred_ins);
 237         } else {
 238                 exchange(pred_block, get_nodes_block(pred_ins[0]));
 239         }
 240 }
 241
 242
 243 static void prepare_path(ir_node* block, int i, const ir_node* dependency)
 244 {
 245         ir_node* pred = get_nodes_block(get_irn_n(block, i));
 246         int pred_arity;
 247         int j;
 248
 249         DB((dbg, LEVEL_1, "Preparing predecessor %d of %+F\n", i, block));
 250
 251         pred_arity = get_irn_arity(pred);
 252         for (j = 0; j < pred_arity; ++j) {
 253                 ir_node* pred_pred = get_nodes_block(get_irn_n(pred, j));
 254
 255                 if (is_cdep_on(pred_pred, dependency)) {
 256                         prepare_path(pred, j, dependency);
 257                         split_block(block, i, j);
 258                         break;
 259                 }
 260         }
 261 }
 262
 263
 264 static void if_conv_walker(ir_node* block, void* env)
 265 {
 266         ir_settings_if_conv_t* opt_info = env;
 267         int arity;
 268         int i;
 269
 270         /* Bail out, if there are no Phis at all */
 271         if (get_block_blockinfo(block)->phi == NULL) return;
 272
 273 restart:
 274         arity = get_irn_arity(block);
 275         for (i = 0; i < arity; ++i) {
 276                 ir_node* pred0;
 277                 cdep* cdep;
 278
 279                 pred0 = get_nodes_block(get_irn_n(block, i));
 280                 for (cdep = find_cdep(pred0); cdep != NULL; cdep = cdep->next) {
 281                         const ir_node* dependency = cdep->node;
 282                         ir_node* projx0 = walk_to_projx(pred0, dependency);
 283                         ir_node* cond;
 284                         int j;
 285
 286                         if (projx0 == NULL) continue;
 287
 288                         cond = get_Proj_pred(projx0);
 289                         if (get_irn_op(cond) != op_Cond) continue;
 290
 291                         /* We only handle boolean decisions, no switches */
 292                         if (get_irn_mode(get_Cond_selector(cond)) != mode_b) continue;
 293
 294                         for (j = i + 1; j < arity; ++j) {
 295                                 ir_node* projx1;
 296                                 ir_node* conds[1];
 297                                 ir_node* psi_block;
 298                                 ir_node* phi;
 299                                 ir_node* pred1;
 300                                 dbg_info* cond_dbg;
 301
 302                                 pred1 = get_nodes_block(get_irn_n(block, j));
 303
 304                                 if (!is_cdep_on(pred1, dependency)) continue;
 305
 306                                 projx1 = walk_to_projx(pred1, dependency);
 307
 308                                 if (projx1 == NULL) continue;
 309
 310                                 phi = get_block_blockinfo(block)->phi;
 311                                 if (!opt_info->allow_ifconv(get_Cond_selector(cond), phi, i, j)) continue;
 312
 313                                 DB((dbg, LEVEL_1, "Found Cond %+F with proj %+F and %+F\n",
 314                                         cond, projx0, projx1
 315                                 ));
 316
 317                                 prepare_path(block, i, dependency);
 318                                 prepare_path(block, j, dependency);
 319                                 arity = get_irn_arity(block);
 320
 321                                 conds[0] = get_Cond_selector(cond);
 322
 323                                 psi_block = get_nodes_block(cond);
 324                                 cond_dbg = get_irn_dbg_info(cond);
 325                                 do {
 326                                         ir_node* val_i = get_irn_n(phi, i);
 327                                         ir_node* val_j = get_irn_n(phi, j);
 328                                         ir_node* psi;
 329                                         ir_node* next_phi;
 330
 331                                         if (val_i == val_j) {
 332                                                 psi = val_i;
 333                                                 DB((dbg, LEVEL_2,  "Generating no psi, because both values are equal\n"));
 334                                         } else {
 335                                                 ir_node* vals[2];
 336
 337                                                 /* Something is very fishy if two predecessors of a PhiM point into
 338                                                  * one block, but not at the same memory node
 339                                                  */
 340                                                 assert(get_irn_mode(phi) != mode_M);
 341                                                 if (get_Proj_proj(projx0) == pn_Cond_true) {
 342                                                         vals[0] = val_i;
 343                                                         vals[1] = val_j;
 344                                                 } else {
 345                                                         vals[0] = val_j;
 346                                                         vals[1] = val_i;
 347                                                 }
 348
 349                                                 psi = new_rd_Psi(cond_dbg, current_ir_graph, psi_block, 1, conds, vals, get_irn_mode(phi));
 350                                                 DB((dbg, LEVEL_2, "Generating %+F for %+F\n", psi, phi));
 351                                         }
 352
 353                                         next_phi = get_irn_link(phi);
 354
 355                                         if (arity == 2) {
 356                                                 exchange(phi, psi);
 357                                         } else {
 358                                                 rewire(phi, i, j, psi);
 359                                         }
 360
 361                                         phi = next_phi;
 362                                 } while (phi != NULL);
 363
 364                                 exchange(get_nodes_block(get_irn_n(block, i)), psi_block);
 365                                 exchange(get_nodes_block(get_irn_n(block, j)), psi_block);
 366
 367                                 if (arity == 2) {
 368 #if 1
 369                                         DB((dbg, LEVEL_1,  "Welding block %+F and %+F\n", block, psi_block));
 370                                         /* copy the block-info from the Psi-block to the block before merging */
 371                                         get_block_blockinfo(psi_block)->has_pinned |= get_block_blockinfo(block)->has_pinned;
 372                                         set_irn_link(block, get_irn_link(psi_block));
 373
 374                                         set_irn_in(block, get_irn_arity(psi_block), get_irn_in(psi_block) + 1);
 375                                         exchange_cdep(psi_block, block);
 376                                         exchange(psi_block, block);
 377 #else
 378                                         DB((dbg, LEVEL_1,  "Welding block %+F to %+F\n", block, psi_block));
 379                                         get_block_blockinfo(psi_block)->has_pinned |=   get_block_blockinfo(block)->has_pinned;
 380                                         exchange(block, psi_block);
 381 #endif
 382                                         return;
 383                                 } else {
 384                                         rewire(block, i, j, new_r_Jmp(current_ir_graph, psi_block));
 385                                         goto restart;
 386                                 }
 387                         }
 388                 }
 389         }
 390 }
 391
 392 /**
 393  * Block walker: add additional data
 394  */
 395 static void init_block_link(ir_node *block, void *env)
 396 {
 397         struct obstack *obst = env;
 398         block_info *bi = obstack_alloc(obst, sizeof(*bi));
 399
 400         bi->phi = NULL;
 401         bi->has_pinned = 0;
 402         set_irn_link(block, bi);
 403 }
 404
 405
 406 /**
 407  * Daisy-chain all phis in a block
 408  * If a non-movable node is encountered set the has_pinned flag
 409  */
 410 static void collect_phis(ir_node *node, void *env)
 411 {
 412         (void) env;
 413
 414         if (is_Phi(node)) {
 415                 ir_node *block = get_nodes_block(node);
 416                 block_info *bi = get_block_blockinfo(block);
 417
 418                 set_irn_link(node, bi->phi);
 419                 bi->phi = node;
 420         } else {
 421                 if (is_no_Block(node) && get_irn_pinned(node) == op_pin_state_pinned) {
 422                         /*
 423                          * Ignore control flow nodes, these will be removed.
 424                          * This ignores Raise. That is surely bad. FIXME.
 425                          */
 426                         if (!is_cfop(node)) {
 427                                 ir_node *block = get_nodes_block(node);
 428                                 block_info *bi = get_block_blockinfo(block);
 429
 430                                 DB((dbg, LEVEL_2, "Node %+F in block %+F is unmovable\n", node, block));
 431                                 bi->has_pinned = 1;
 432                         }
 433                 }
 434         }
 435 }
 436
 437 static void optimise_psis_0(ir_node* psi, void* env)
 438 {
 439         ir_node* t;
 440         ir_node* f;
 441
 442         (void) env;
 443
 444         if (!is_Psi(psi)) return;
 445
 446         t = get_Psi_val(psi, 0);
 447         f = get_Psi_default(psi);
 448
 449         DB((dbg, LEVEL_3, "Simplify %+F T=%+F F=%+F\n", psi, t, f));
 450
 451         if (is_Unknown(t)) {
 452                 DB((dbg, LEVEL_3, "Replace Psi with unknown operand by %+F\n", f));
 453                 exchange(psi, f);
 454                 return;
 455         }
 456         if (is_Unknown(f)) {
 457                 DB((dbg, LEVEL_3, "Replace Psi with unknown operand by %+F\n", t));
 458                 exchange(psi, t);
 459                 return;
 460         }
 461
 462         if (is_Psi(t)) {
 463                 ir_graph* irg   = current_ir_graph;
 464                 ir_node*  block = get_nodes_block(psi);
 465                 ir_mode*  mode  = get_irn_mode(psi);
 466                 ir_node*  c0    = get_Psi_cond(psi, 0);
 467                 ir_node*  c1    = get_Psi_cond(t, 0);
 468                 ir_node*  t1    = get_Psi_val(t, 0);
 469                 ir_node*  f1    = get_Psi_default(t);
 470                 if (f == f1) {
 471                         /* Psi(c0, Psi(c1, x, y), y) -> typical if (c0 && c1) x else y */
 472                         ir_node* and_    = new_r_And(irg, block, c0, c1, mode_b);
 473                         ir_node* vals[2] = { t1, f1 };
 474                         ir_node* new_psi = new_r_Psi(irg, block, 1, &and_, vals, mode);
 475                         exchange(psi, new_psi);
 476                 } else if (f == t1) {
 477                         /* Psi(c0, Psi(c1, x, y), x) */
 478                         ir_node* not_c1 = new_r_Not(irg, block, c1, mode_b);
 479                         ir_node* and_   = new_r_And(irg, block, c0, not_c1, mode_b);
 480                         ir_node* vals[2] = { f1, t1 };
 481                         ir_node* new_psi = new_r_Psi(irg, block, 1, &and_, vals, mode);
 482                         exchange(psi, new_psi);
 483                 }
 484         } else if (is_Psi(f)) {
 485                 ir_graph* irg   = current_ir_graph;
 486                 ir_node*  block = get_nodes_block(psi);
 487                 ir_mode*  mode  = get_irn_mode(psi);
 488                 ir_node*  c0    = get_Psi_cond(psi, 0);
 489                 ir_node*  c1    = get_Psi_cond(f, 0);
 490                 ir_node*  t1    = get_Psi_val(f, 0);
 491                 ir_node*  f1    = get_Psi_default(f);
 492                 if (t == t1) {
 493                         /* Psi(c0, x, Psi(c1, x, y)) -> typical if (c0 || c1) x else y */
 494                         ir_node* or_     = new_r_Or(irg, block, c0, c1, mode_b);
 495                         ir_node* vals[2] = { t1, f1 };
 496                         ir_node* new_psi = new_r_Psi(irg, block, 1, &or_, vals, mode);
 497                         exchange(psi, new_psi);
 498                 } else if (t == f1) {
 499                         /* Psi(c0, x, Psi(c1, y, x)) */
 500                         ir_node* not_c1  = new_r_Not(irg, block, c1, mode_b);
 501                         ir_node* or_     = new_r_Or(irg, block, c0, not_c1, mode_b);
 502                         ir_node* vals[2] = { f1, t1 };
 503                         ir_node* new_psi = new_r_Psi(irg, block, 1, &or_, vals, mode);
 504                         exchange(psi, new_psi);
 505                 }
 506         }
 507 }
 508
 509
 510 static void optimise_psis_1(ir_node* psi, void* env)
 511 {
 512         ir_node* t;
 513         ir_node* f;
 514         ir_mode* mode;
 515
 516         (void) env;
 517
 518         if (!is_Psi(psi)) return;
 519
 520         t = get_Psi_val(psi, 0);
 521         f = get_Psi_default(psi);
 522
 523         DB((dbg, LEVEL_3, "Simplify %+F T=%+F F=%+F\n", psi, t, f));
 524
 525         mode = get_irn_mode(psi);
 526
 527         if (is_Const(t) && is_Const(f) && (mode_is_int(mode))) {
 528                 ir_node* block = get_nodes_block(psi);
 529                 ir_node* c     = get_Psi_cond(psi, 0);
 530                 tarval* tv_t = get_Const_tarval(t);
 531                 tarval* tv_f = get_Const_tarval(f);
 532                 if (tarval_is_one(tv_t) && tarval_is_null(tv_f)) {
 533                         ir_node* conv  = new_r_Conv(current_ir_graph, block, c, mode);
 534                         exchange(psi, conv);
 535                 } else if (tarval_is_null(tv_t) && tarval_is_one(tv_f)) {
 536                         ir_node* not_  = new_r_Not(current_ir_graph, block, c, mode_b);
 537                         ir_node* conv  = new_r_Conv(current_ir_graph, block, not_, mode);
 538                         exchange(psi, conv);
 539                 }
 540         }
 541 }
 542
 543
 544 void opt_if_conv(ir_graph *irg, const ir_settings_if_conv_t *params)
 545 {
 546         struct obstack obst;
 547         ir_settings_if_conv_t p;
 548
 549         /* get the parameters */
 550         p = (params != NULL ? *params : default_info);
 551
 552         FIRM_DBG_REGISTER(dbg, "firm.opt.ifconv");
 553
 554         DB((dbg, LEVEL_1, "Running if-conversion on %+F\n", irg));
 555
 556         normalize_one_return(irg);
 557         remove_critical_cf_edges(irg);
 558
 559         compute_cdep(irg);
 560         assure_doms(irg);
 561
 562         obstack_init(&obst);
 563         irg_block_walk_graph(irg, init_block_link, NULL, &obst);
 564         irg_walk_graph(irg, collect_phis, NULL, NULL);
 565         irg_block_walk_graph(irg, NULL, if_conv_walker, &p);
 566
 567         local_optimize_graph(irg);
 568
 569         irg_walk_graph(irg, NULL, optimise_psis_0, NULL);
 570 #if 1
 571         irg_walk_graph(irg, NULL, optimise_psis_1, NULL);
 572 #endif
 573
 574         obstack_free(&obst, NULL);
 575
 576         free_dom(irg);
 577         free_cdep(irg);
 578 }