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 /** Returns the additional block info of a block. */
  78 static INLINE block_info* get_block_blockinfo(const ir_node* block) {
  79         return get_irn_link(block);
  80 }
  81
  82
  83 /**
  84  * Returns non-zero if a Block can be emptied.
  85  */
  86 static int can_empty_block(ir_node *block) {
  87         return !get_block_blockinfo(block)->has_pinned;
  88 }
  89
  90
  91 static ir_node* walk_to_projx(ir_node* start, const ir_node* dependency)
  92 {
  93         int arity;
  94         int i;
  95
  96         /* No need to find the conditional block if this block cannot be emptied and
  97          * therefore not moved */
  98         if (!can_empty_block(start)) return NULL;
  99
 100         arity = get_irn_arity(start);
 101         for (i = 0; i < arity; ++i) {
 102                 ir_node* pred = get_irn_n(start, i);
 103                 ir_node* pred_block = get_nodes_block(pred);
 104
 105                 if (pred_block == dependency) {
 106                         if (is_Proj(pred)) {
 107                                 assert(get_irn_mode(pred) == mode_X);
 108                                 return pred;
 109                         }
 110                         return NULL;
 111                 }
 112
 113                 if (is_Proj(pred)) {
 114                         assert(get_irn_mode(pred) == mode_X);
 115                         return NULL;
 116                 }
 117
 118                 if (is_cdep_on(pred_block, dependency)) {
 119                         return walk_to_projx(pred_block, dependency);
 120                 }
 121         }
 122         return NULL;
 123 }
 124
 125
 126 /**
 127  * Copies the DAG starting at node to the ith predecessor block of src_block
 128  * -if the node isn't in the src_block, this is a nop and the node is returned
 129  * -if the node is a phi in the src_block, the ith predecessor of the phi is
 130  *   returned
 131  * otherwise returns the copy of the passed node
 132  */
 133 static ir_node* copy_to(ir_node* node, ir_node* src_block, int i)
 134 {
 135         ir_node* dst_block;
 136         ir_node* copy;
 137         int arity;
 138         int j;
 139
 140         if (get_nodes_block(node) != src_block) return node;
 141         if (get_irn_op(node) == op_Phi) return get_irn_n(node, i);
 142
 143         copy = exact_copy(node);
 144         dst_block = get_nodes_block(get_irn_n(src_block, i));
 145         set_nodes_block(copy, dst_block);
 146
 147         DB((dbg, LEVEL_1, "Copying node %+F to block %+F, copy is %+F\n",
 148                 node, dst_block, copy));
 149
 150         arity = get_irn_arity(node);
 151         for (j = 0; j < arity; ++j) {
 152                 set_irn_n(copy, j, copy_to(get_irn_n(node, j), src_block, i));
 153                 DB((dbg, LEVEL_2, "-- pred %d is %+F\n", j, get_irn_n(copy, j)));
 154         }
 155         return copy;
 156 }
 157
 158
 159 /**
 160  * Remove predecessors i and j from node and add predecessor new_pred
 161  */
 162 static void rewire(ir_node* node, int i, int j, ir_node* new_pred)
 163 {
 164         int arity = get_irn_arity(node);
 165         ir_node **ins;
 166         int k;
 167         int l;
 168
 169         NEW_ARR_A(ir_node *, ins, arity - 1);
 170
 171         l = 0;
 172         for (k = 0; k < i;     ++k) ins[l++] = get_irn_n(node, k);
 173         for (++k;   k < j;     ++k) ins[l++] = get_irn_n(node, k);
 174         for (++k;   k < arity; ++k) ins[l++] = get_irn_n(node, k);
 175         ins[l++] = new_pred;
 176         assert(l == arity - 1);
 177         set_irn_in(node, l, ins);
 178 }
 179
 180
 181 /**
 182  * Remove the jth predecessors from the ith predecessor of block and add it to block
 183  */
 184 static void split_block(ir_node* block, int i, int j)
 185 {
 186         ir_node* pred_block = get_nodes_block(get_irn_n(block, i));
 187         int arity = get_irn_arity(block);
 188         int new_pred_arity;
 189         ir_node* phi;
 190         ir_node **ins;
 191         ir_node **pred_ins;
 192         int k;
 193
 194         DB((dbg, LEVEL_1, "Splitting predecessor %d of predecessor %d of %+F\n", j, i, block));
 195
 196         NEW_ARR_A(ir_node*, ins, arity + 1);
 197
 198         for (phi = get_block_blockinfo(block)->phi; phi != NULL; phi = get_irn_link(phi)) {
 199                 ir_node* copy = copy_to(get_irn_n(phi, i), pred_block, j);
 200
 201                 for (k = 0; k < i; ++k) ins[k] = get_irn_n(phi, k);
 202                 ins[k++] = copy;
 203                 for (; k < arity; ++k) ins[k] = get_irn_n(phi, k);
 204                 ins[k] = get_irn_n(phi, i);
 205                 assert(k == arity);
 206                 set_irn_in(phi, arity + 1, ins);
 207         }
 208
 209         for (k = 0; k < i; ++k) ins[k] = get_irn_n(block, k);
 210         ins[k++] = get_irn_n(pred_block, j);
 211         for (; k < arity; ++k) ins[k] = get_irn_n(block, k);
 212         ins[k] = get_irn_n(block, i);
 213         assert(k == arity);
 214         set_irn_in(block, arity + 1, ins);
 215
 216         new_pred_arity = get_irn_arity(pred_block) - 1;
 217         NEW_ARR_A(ir_node*, pred_ins, new_pred_arity);
 218
 219         for (phi = get_block_blockinfo(pred_block)->phi; phi != NULL; phi = get_irn_link(phi)) {
 220                 for (k = 0; k < j; ++k) pred_ins[k] = get_irn_n(phi, k);
 221                 for (; k < new_pred_arity; ++k) pred_ins[k] = get_irn_n(phi, k + 1);
 222                 assert(k == new_pred_arity);
 223                 if (new_pred_arity > 1) {
 224                         set_irn_in(phi, new_pred_arity, pred_ins);
 225                 } else {
 226                         exchange(phi, pred_ins[0]);
 227                 }
 228         }
 229
 230         for (k = 0; k < j; ++k) pred_ins[k] = get_irn_n(pred_block, k);
 231         for (; k < new_pred_arity; ++k) pred_ins[k] = get_irn_n(pred_block, k + 1);
 232         assert(k == new_pred_arity);
 233         if (new_pred_arity > 1) {
 234                 set_irn_in(pred_block, new_pred_arity, pred_ins);
 235         } else {
 236                 exchange(pred_block, get_nodes_block(pred_ins[0]));
 237         }
 238 }
 239
 240
 241 static void prepare_path(ir_node* block, int i, const ir_node* dependency)
 242 {
 243         ir_node* pred = get_nodes_block(get_irn_n(block, i));
 244         int pred_arity;
 245         int j;
 246
 247         DB((dbg, LEVEL_1, "Preparing predecessor %d of %+F\n", i, block));
 248
 249         pred_arity = get_irn_arity(pred);
 250         for (j = 0; j < pred_arity; ++j) {
 251                 ir_node* pred_pred = get_nodes_block(get_irn_n(pred, j));
 252
 253                 if (is_cdep_on(pred_pred, dependency)) {
 254                         prepare_path(pred, j, dependency);
 255                         split_block(block, i, j);
 256                         break;
 257                 }
 258         }
 259 }
 260
 261
 262 static void if_conv_walker(ir_node* block, void* env)
 263 {
 264         ir_settings_if_conv_t* opt_info = env;
 265         int arity;
 266         int i;
 267
 268         /* Bail out, if there are no Phis at all */
 269         if (get_block_blockinfo(block)->phi == NULL) return;
 270
 271 restart:
 272         arity = get_irn_arity(block);
 273         for (i = 0; i < arity; ++i) {
 274                 ir_node* pred0;
 275                 ir_cdep* cdep;
 276
 277                 pred0 = get_nodes_block(get_irn_n(block, i));
 278                 for (cdep = find_cdep(pred0); cdep != NULL; cdep = cdep->next) {
 279                         const ir_node* dependency = cdep->node;
 280                         ir_node* projx0 = walk_to_projx(pred0, dependency);
 281                         ir_node* cond;
 282                         int j;
 283
 284                         if (projx0 == NULL) continue;
 285
 286                         cond = get_Proj_pred(projx0);
 287                         if (get_irn_op(cond) != op_Cond) continue;
 288
 289                         /* We only handle boolean decisions, no switches */
 290                         if (get_irn_mode(get_Cond_selector(cond)) != mode_b) continue;
 291
 292                         for (j = i + 1; j < arity; ++j) {
 293                                 ir_node* projx1;
 294                                 ir_node* conds[1];
 295                                 ir_node* psi_block;
 296                                 ir_node* phi;
 297                                 ir_node* pred1;
 298                                 dbg_info* cond_dbg;
 299
 300                                 pred1 = get_nodes_block(get_irn_n(block, j));
 301
 302                                 if (!is_cdep_on(pred1, dependency)) continue;
 303
 304                                 projx1 = walk_to_projx(pred1, dependency);
 305
 306                                 if (projx1 == NULL) continue;
 307
 308                                 phi = get_block_blockinfo(block)->phi;
 309                                 if (!opt_info->allow_ifconv(get_Cond_selector(cond), phi, i, j)) continue;
 310
 311                                 DB((dbg, LEVEL_1, "Found Cond %+F with proj %+F and %+F\n",
 312                                         cond, projx0, projx1
 313                                 ));
 314
 315                                 prepare_path(block, i, dependency);
 316                                 prepare_path(block, j, dependency);
 317                                 arity = get_irn_arity(block);
 318
 319                                 conds[0] = get_Cond_selector(cond);
 320
 321                                 psi_block = get_nodes_block(cond);
 322                                 cond_dbg = get_irn_dbg_info(cond);
 323                                 do {
 324                                         ir_node* val_i = get_irn_n(phi, i);
 325                                         ir_node* val_j = get_irn_n(phi, j);
 326                                         ir_node* psi;
 327                                         ir_node* next_phi;
 328
 329                                         if (val_i == val_j) {
 330                                                 psi = val_i;
 331                                                 DB((dbg, LEVEL_2,  "Generating no psi, because both values are equal\n"));
 332                                         } else {
 333                                                 ir_node* vals[2];
 334
 335                                                 /* Something is very fishy if two predecessors of a PhiM point into
 336                                                  * one block, but not at the same memory node
 337                                                  */
 338                                                 assert(get_irn_mode(phi) != mode_M);
 339                                                 if (get_Proj_proj(projx0) == pn_Cond_true) {
 340                                                         vals[0] = val_i;
 341                                                         vals[1] = val_j;
 342                                                 } else {
 343                                                         vals[0] = val_j;
 344                                                         vals[1] = val_i;
 345                                                 }
 346
 347                                                 psi = new_rd_Psi(cond_dbg, current_ir_graph, psi_block, 1, conds, vals, get_irn_mode(phi));
 348                                                 DB((dbg, LEVEL_2, "Generating %+F for %+F\n", psi, phi));
 349                                         }
 350
 351                                         next_phi = get_irn_link(phi);
 352
 353                                         if (arity == 2) {
 354                                                 exchange(phi, psi);
 355                                         } else {
 356                                                 rewire(phi, i, j, psi);
 357                                         }
 358
 359                                         phi = next_phi;
 360                                 } while (phi != NULL);
 361
 362                                 exchange(get_nodes_block(get_irn_n(block, i)), psi_block);
 363                                 exchange(get_nodes_block(get_irn_n(block, j)), psi_block);
 364
 365                                 if (arity == 2) {
 366 #if 1
 367                                         DB((dbg, LEVEL_1,  "Welding block %+F and %+F\n", block, psi_block));
 368                                         /* copy the block-info from the Psi-block to the block before merging */
 369                                         get_block_blockinfo(psi_block)->has_pinned |= get_block_blockinfo(block)->has_pinned;
 370                                         set_irn_link(block, get_irn_link(psi_block));
 371
 372                                         set_irn_in(block, get_irn_arity(psi_block), get_irn_in(psi_block) + 1);
 373                                         exchange_cdep(psi_block, block);
 374                                         exchange(psi_block, block);
 375 #else
 376                                         DB((dbg, LEVEL_1,  "Welding block %+F to %+F\n", block, psi_block));
 377                                         get_block_blockinfo(psi_block)->has_pinned |=   get_block_blockinfo(block)->has_pinned;
 378                                         exchange(block, psi_block);
 379 #endif
 380                                         return;
 381                                 } else {
 382                                         rewire(block, i, j, new_r_Jmp(current_ir_graph, psi_block));
 383                                         goto restart;
 384                                 }
 385                         }
 386                 }
 387         }
 388 }
 389
 390 /**
 391  * Block walker: add additional data
 392  */
 393 static void init_block_link(ir_node *block, void *env)
 394 {
 395         struct obstack *obst = env;
 396         block_info *bi = obstack_alloc(obst, sizeof(*bi));
 397
 398         bi->phi = NULL;
 399         bi->has_pinned = 0;
 400         set_irn_link(block, bi);
 401 }
 402
 403
 404 /**
 405  * Daisy-chain all phis in a block
 406  * If a non-movable node is encountered set the has_pinned flag in its block.
 407  */
 408 static void collect_phis(ir_node *node, void *env) {
 409         (void) env;
 410
 411         if (is_Phi(node)) {
 412                 ir_node *block = get_nodes_block(node);
 413                 block_info *bi = get_block_blockinfo(block);
 414
 415                 set_irn_link(node, bi->phi);
 416                 bi->phi = node;
 417         } else {
 418                 if (is_no_Block(node) && get_irn_pinned(node) == op_pin_state_pinned) {
 419                         /*
 420                          * Ignore control flow nodes, these will be removed.
 421                          * This ignores Raise. That is surely bad. FIXME.
 422                          */
 423                         if (!is_cfop(node)) {
 424                                 ir_node *block = get_nodes_block(node);
 425                                 block_info *bi = get_block_blockinfo(block);
 426
 427                                 DB((dbg, LEVEL_2, "Node %+F in block %+F is unmovable\n", node, block));
 428                                 bi->has_pinned = 1;
 429                         }
 430                 }
 431         }
 432 }
 433
 434 static void optimise_psis_0(ir_node* psi, void* env)
 435 {
 436         ir_node* t;
 437         ir_node* f;
 438
 439         (void) env;
 440
 441         if (!is_Psi(psi)) return;
 442
 443         t = get_Psi_val(psi, 0);
 444         f = get_Psi_default(psi);
 445
 446         DB((dbg, LEVEL_3, "Simplify %+F T=%+F F=%+F\n", psi, t, f));
 447
 448         if (is_Unknown(t)) {
 449                 DB((dbg, LEVEL_3, "Replace Psi with unknown operand by %+F\n", f));
 450                 exchange(psi, f);
 451                 return;
 452         }
 453         if (is_Unknown(f)) {
 454                 DB((dbg, LEVEL_3, "Replace Psi with unknown operand by %+F\n", t));
 455                 exchange(psi, t);
 456                 return;
 457         }
 458
 459         if (is_Psi(t)) {
 460                 ir_graph* irg   = current_ir_graph;
 461                 ir_node*  block = get_nodes_block(psi);
 462                 ir_mode*  mode  = get_irn_mode(psi);
 463                 ir_node*  c0    = get_Psi_cond(psi, 0);
 464                 ir_node*  c1    = get_Psi_cond(t, 0);
 465                 ir_node*  t1    = get_Psi_val(t, 0);
 466                 ir_node*  f1    = get_Psi_default(t);
 467                 if (f == f1) {
 468                         /* Psi(c0, Psi(c1, x, y), y) -> typical if (c0 && c1) x else y */
 469                         ir_node* and_    = new_r_And(irg, block, c0, c1, mode_b);
 470                         ir_node* vals[2] = { t1, f1 };
 471                         ir_node* new_psi = new_r_Psi(irg, block, 1, &and_, vals, mode);
 472                         exchange(psi, new_psi);
 473                 } else if (f == t1) {
 474                         /* Psi(c0, Psi(c1, x, y), x) */
 475                         ir_node* not_c1 = new_r_Not(irg, block, c1, mode_b);
 476                         ir_node* and_   = new_r_And(irg, block, c0, not_c1, mode_b);
 477                         ir_node* vals[2] = { f1, t1 };
 478                         ir_node* new_psi = new_r_Psi(irg, block, 1, &and_, vals, mode);
 479                         exchange(psi, new_psi);
 480                 }
 481         } else if (is_Psi(f)) {
 482                 ir_graph* irg   = current_ir_graph;
 483                 ir_node*  block = get_nodes_block(psi);
 484                 ir_mode*  mode  = get_irn_mode(psi);
 485                 ir_node*  c0    = get_Psi_cond(psi, 0);
 486                 ir_node*  c1    = get_Psi_cond(f, 0);
 487                 ir_node*  t1    = get_Psi_val(f, 0);
 488                 ir_node*  f1    = get_Psi_default(f);
 489                 if (t == t1) {
 490                         /* Psi(c0, x, Psi(c1, x, y)) -> typical if (c0 || c1) x else y */
 491                         ir_node* or_     = new_r_Or(irg, block, c0, c1, mode_b);
 492                         ir_node* vals[2] = { t1, f1 };
 493                         ir_node* new_psi = new_r_Psi(irg, block, 1, &or_, vals, mode);
 494                         exchange(psi, new_psi);
 495                 } else if (t == f1) {
 496                         /* Psi(c0, x, Psi(c1, y, x)) */
 497                         ir_node* not_c1  = new_r_Not(irg, block, c1, mode_b);
 498                         ir_node* or_     = new_r_Or(irg, block, c0, not_c1, mode_b);
 499                         ir_node* vals[2] = { f1, t1 };
 500                         ir_node* new_psi = new_r_Psi(irg, block, 1, &or_, vals, mode);
 501                         exchange(psi, new_psi);
 502                 }
 503         }
 504 }
 505
 506
 507 static void optimise_psis_1(ir_node* psi, void* env)
 508 {
 509         ir_node* t;
 510         ir_node* f;
 511         ir_mode* mode;
 512
 513         (void) env;
 514
 515         if (!is_Psi(psi)) return;
 516
 517         t = get_Psi_val(psi, 0);
 518         f = get_Psi_default(psi);
 519
 520         DB((dbg, LEVEL_3, "Simplify %+F T=%+F F=%+F\n", psi, t, f));
 521
 522         mode = get_irn_mode(psi);
 523
 524         if (is_Const(t) && is_Const(f) && (mode_is_int(mode))) {
 525                 ir_node* block = get_nodes_block(psi);
 526                 ir_node* c     = get_Psi_cond(psi, 0);
 527                 tarval* tv_t = get_Const_tarval(t);
 528                 tarval* tv_f = get_Const_tarval(f);
 529                 if (tarval_is_one(tv_t) && tarval_is_null(tv_f)) {
 530                         ir_node* conv  = new_r_Conv(current_ir_graph, block, c, mode);
 531                         exchange(psi, conv);
 532                 } else if (tarval_is_null(tv_t) && tarval_is_one(tv_f)) {
 533                         ir_node* not_  = new_r_Not(current_ir_graph, block, c, mode_b);
 534                         ir_node* conv  = new_r_Conv(current_ir_graph, block, not_, mode);
 535                         exchange(psi, conv);
 536                 }
 537         }
 538 }
 539
 540
 541 void opt_if_conv(ir_graph *irg, const ir_settings_if_conv_t *params)
 542 {
 543         struct obstack obst;
 544         ir_settings_if_conv_t p;
 545
 546         /* get the parameters */
 547         p = (params != NULL ? *params : default_info);
 548
 549         FIRM_DBG_REGISTER(dbg, "firm.opt.ifconv");
 550
 551         DB((dbg, LEVEL_1, "Running if-conversion on %+F\n", irg));
 552
 553         normalize_one_return(irg);
 554         remove_critical_cf_edges(irg);
 555
 556         compute_cdep(irg);
 557         assure_doms(irg);
 558
 559         set_using_irn_link(irg);
 560
 561         obstack_init(&obst);
 562         irg_block_walk_graph(irg, init_block_link, NULL, &obst);
 563         irg_walk_graph(irg, collect_phis, NULL, NULL);
 564         irg_block_walk_graph(irg, NULL, if_conv_walker, &p);
 565
 566         clear_using_irn_link(irg);
 567
 568         local_optimize_graph(irg);
 569
 570         irg_walk_graph(irg, NULL, optimise_psis_0, NULL);
 571 #if 1
 572         irg_walk_graph(irg, NULL, optimise_psis_1, NULL);
 573 #endif
 574
 575         obstack_free(&obst, NULL);
 576
 577         /* TODO: graph might be changed, handle more gracefull */
 578         set_irg_outs_inconsistent(irg);
 579         free_dom(irg);
 580
 581         free_cdep(irg);
 582 }