nsz Git - libfirm/blob - ir/be/bepeephole.c

   1 /*
   2  * Copyright (C) 1995-2011 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       Peephole optimisation framework keeps track of which registers contain which values
  23  * @author      Matthias Braun
  24  * @version     $Id$
  25  */
  26 #include "config.h"
  27
  28 #include "array_t.h"
  29 #include "bepeephole.h"
  30
  31 #include "iredges_t.h"
  32 #include "irgwalk.h"
  33 #include "irprintf.h"
  34 #include "ircons.h"
  35 #include "irgmod.h"
  36 #include "error.h"
  37
  38 #include "beirg.h"
  39 #include "belive_t.h"
  40 #include "bearch.h"
  41 #include "benode.h"
  42 #include "besched.h"
  43 #include "bemodule.h"
  44
  45 DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)
  46
  47 static const arch_env_t *arch_env;
  48 static be_lv_t          *lv;
  49 static ir_node          *current_node;
  50 ir_node               ***register_values;
  51
  52 static void clear_reg_value(ir_node *node)
  53 {
  54         const arch_register_t       *reg;
  55         const arch_register_class_t *cls;
  56         unsigned                     reg_idx;
  57         unsigned                     cls_idx;
  58
  59         if (!mode_is_data(get_irn_mode(node)))
  60                 return;
  61
  62         reg     = arch_get_irn_register(node);
  63         if (reg == NULL) {
  64                 panic("No register assigned at %+F", node);
  65         }
  66         if (reg->type & arch_register_type_virtual)
  67                 return;
  68         cls     = arch_register_get_class(reg);
  69         reg_idx = arch_register_get_index(reg);
  70         cls_idx = arch_register_class_index(cls);
  71
  72         //assert(register_values[cls_idx][reg_idx] != NULL);
  73         DB((dbg, LEVEL_1, "Clear Register %s\n", reg->name));
  74         register_values[cls_idx][reg_idx] = NULL;
  75 }
  76
  77 static void set_reg_value(ir_node *node)
  78 {
  79         const arch_register_t       *reg;
  80         const arch_register_class_t *cls;
  81         unsigned                     reg_idx;
  82         unsigned                     cls_idx;
  83
  84         if (!mode_is_data(get_irn_mode(node)))
  85                 return;
  86
  87         reg = arch_get_irn_register(node);
  88         if (reg == NULL) {
  89                 panic("No register assigned at %+F", node);
  90         }
  91         if (reg->type & arch_register_type_virtual)
  92                 return;
  93         cls     = arch_register_get_class(reg);
  94         reg_idx = arch_register_get_index(reg);
  95         cls_idx = arch_register_class_index(cls);
  96
  97         DB((dbg, LEVEL_1, "Set Register %s: %+F\n", reg->name, node));
  98         register_values[cls_idx][reg_idx] = node;
  99 }
 100
 101 static void clear_defs(ir_node *node)
 102 {
 103         /* clear values defined */
 104         if (get_irn_mode(node) == mode_T) {
 105                 const ir_edge_t *edge;
 106                 foreach_out_edge(node, edge) {
 107                         ir_node *proj = get_edge_src_irn(edge);
 108                         clear_reg_value(proj);
 109                 }
 110         } else {
 111                 clear_reg_value(node);
 112         }
 113 }
 114
 115 static void set_uses(ir_node *node)
 116 {
 117         int i, arity;
 118
 119         /* set values used */
 120         arity = get_irn_arity(node);
 121         for (i = 0; i < arity; ++i) {
 122                 ir_node *in = get_irn_n(node, i);
 123                 set_reg_value(in);
 124         }
 125 }
 126
 127 void be_peephole_new_node(ir_node * nw)
 128 {
 129         be_liveness_introduce(lv, nw);
 130 }
 131
 132 /**
 133  * must be called from peephole optimisations before a node will be killed
 134  * and its users will be redirected to new_node.
 135  * so bepeephole can update it's internal state.
 136  *
 137  * Note: killing a node and rewiring os only allowed if new_node produces
 138  * the same registers as old_node.
 139  */
 140 static void be_peephole_before_exchange(const ir_node *old_node,
 141                                         ir_node *new_node)
 142 {
 143         const arch_register_t       *reg;
 144         const arch_register_class_t *cls;
 145         unsigned                     reg_idx;
 146         unsigned                     cls_idx;
 147
 148         DB((dbg, LEVEL_1, "About to exchange and kill %+F with %+F\n", old_node, new_node));
 149
 150         if (current_node == old_node) {
 151                 /* next node to be processed will be killed. Its scheduling predecessor
 152                  * must be processed next. */
 153                 current_node = sched_next(current_node);
 154                 assert (!is_Bad(current_node));
 155         }
 156
 157         if (!mode_is_data(get_irn_mode(old_node)))
 158                 return;
 159
 160         reg = arch_get_irn_register(old_node);
 161         if (reg == NULL) {
 162                 panic("No register assigned at %+F", old_node);
 163         }
 164         assert(reg == arch_get_irn_register(new_node) &&
 165               "KILLING a node and replacing by different register is not allowed");
 166
 167         cls     = arch_register_get_class(reg);
 168         reg_idx = arch_register_get_index(reg);
 169         cls_idx = arch_register_class_index(cls);
 170
 171         if (register_values[cls_idx][reg_idx] == old_node) {
 172                 register_values[cls_idx][reg_idx] = new_node;
 173         }
 174
 175         be_liveness_remove(lv, old_node);
 176 }
 177
 178 void be_peephole_exchange(ir_node *old, ir_node *nw)
 179 {
 180         be_peephole_before_exchange(old, nw);
 181         sched_remove(old);
 182         exchange(old, nw);
 183         be_peephole_new_node(nw);
 184 }
 185
 186 /**
 187  * block-walker: run peephole optimization on the given block.
 188  */
 189 static void process_block(ir_node *block, void *data)
 190 {
 191         unsigned n_classes;
 192         unsigned i;
 193         int l;
 194         (void) data;
 195
 196         /* construct initial register assignment */
 197         n_classes = arch_env->n_register_classes;
 198         for (i = 0; i < n_classes; ++i) {
 199                 const arch_register_class_t *cls    = &arch_env->register_classes[i];
 200                 unsigned                     n_regs = arch_register_class_n_regs(cls);
 201                 memset(register_values[i], 0, sizeof(ir_node*) * n_regs);
 202         }
 203
 204         assert(lv->nodes && "live sets must be computed");
 205         DB((dbg, LEVEL_1, "\nProcessing block %+F (from end)\n", block));
 206         be_lv_foreach(lv, block, be_lv_state_end, l) {
 207                 ir_node *node = be_lv_get_irn(lv, block, l);
 208                 set_reg_value(node);
 209         }
 210         DB((dbg, LEVEL_1, "\nstart processing\n"));
 211
 212         /* walk the block from last insn to the first */
 213         current_node = sched_last(block);
 214         for ( ; !sched_is_begin(current_node);
 215                         current_node = sched_prev(current_node)) {
 216                 ir_op             *op;
 217                 peephole_opt_func  peephole_node;
 218
 219                 assert(!is_Bad(current_node));
 220                 if (is_Phi(current_node))
 221                         break;
 222
 223                 clear_defs(current_node);
 224                 set_uses(current_node);
 225
 226                 op            = get_irn_op(current_node);
 227                 peephole_node = (peephole_opt_func)op->ops.generic;
 228                 if (peephole_node == NULL)
 229                         continue;
 230
 231                 DB((dbg, LEVEL_2, "optimize %+F\n", current_node));
 232                 peephole_node(current_node);
 233                 assert(!is_Bad(current_node));
 234         }
 235 }
 236
 237 static void kill_node_and_preds(ir_node *node)
 238 {
 239         ir_graph *irg = get_irn_irg(node);
 240         int arity, i;
 241
 242         arity = get_irn_arity(node);
 243         for (i = 0; i < arity; ++i) {
 244                 ir_node *pred = get_irn_n(node, i);
 245
 246                 set_irn_n(node, i, new_r_Bad(irg));
 247                 if (get_irn_n_edges(pred) != 0)
 248                         continue;
 249
 250                 kill_node_and_preds(pred);
 251         }
 252
 253         if (!is_Proj(node))
 254                 sched_remove(node);
 255         kill_node(node);
 256 }
 257
 258 static void keep_alive_barrier_operand(ir_node* operand)
 259 {
 260         ir_node *schedpoint = skip_Proj(operand);
 261
 262         do {
 263                 schedpoint = sched_next(schedpoint);
 264         } while (is_Phi(schedpoint));
 265
 266         /* There already is a keep in the schedule. */
 267         if (be_is_Keep(schedpoint)) {
 268                 const arch_register_class_t *cls = arch_get_irn_reg_class_out(operand);
 269                 be_Keep_add_node(schedpoint, cls, operand);
 270         } else {
 271                 ir_node *block = get_nodes_block(operand);
 272                 ir_node *in[1] = {operand};
 273                 ir_node *keep =  be_new_Keep(block, 1, in);
 274                 sched_add_before(schedpoint, keep);
 275         }
 276 }
 277
 278 /**
 279  * Walk through the block schedule and skip all barrier nodes.
 280  */
 281 static void skip_barrier(ir_node *block, ir_graph *irg)
 282 {
 283         ir_node *irn;
 284
 285         sched_foreach_reverse(block, irn) {
 286                 int       arity;
 287                 unsigned *used;
 288                 size_t    n_used;
 289                 const ir_edge_t *edge, *next;
 290
 291                 if (!be_is_Barrier(irn))
 292                         continue;
 293
 294                 /* track which outputs are actually used, as we have to create
 295                  * keep nodes for unused outputs */
 296                 arity = get_irn_arity(irn);
 297                 rbitset_alloca(used, arity);
 298
 299                 foreach_out_edge_safe(irn, edge, next) {
 300                         ir_node *proj = get_edge_src_irn(edge);
 301                         int      pn;
 302                         ir_node *pred;
 303
 304                         if (is_Anchor(proj))
 305                                 continue;
 306
 307                         pn   = (int) get_Proj_proj(proj);
 308                         pred = get_irn_n(irn, pn);
 309
 310                         rbitset_set(used, pn);
 311
 312                         /* We may need to reschedule be_Keeps to keep live-ranges short. */
 313                         if (get_irn_n_edges(proj) == 1) {
 314                                 const ir_edge_t *proj_edge = get_irn_out_edge_first(proj);
 315                                 ir_node         *proj_succ = get_edge_src_irn(proj_edge);
 316
 317                                 if (be_is_Keep(proj_succ)) {
 318                                         int succ_arity = get_irn_arity(proj_succ);
 319                                         ir_node *operand = get_irn_n(irn, pn);
 320
 321                                         keep_alive_barrier_operand(operand);
 322
 323                                         /* Disconnect old be_Keep. */
 324                                         if (succ_arity > 1) {
 325                                                 int      edge_pos        = get_edge_src_pos(proj_edge);
 326                                                 int      new_arity       = succ_arity - 1;
 327                                                 int      pos;
 328                                                 int      new_pos         = 0;
 329                                                 ir_node **ins;
 330
 331                                                 NEW_ARR_A(ir_node *, ins, succ_arity);
 332                                                 for (pos = 0; pos < succ_arity; ++pos) {
 333                                                         if (pos != edge_pos)
 334                                                                 ins[new_pos++] = get_irn_n(proj_succ, pos);
 335                                                 }
 336
 337                                                 set_irn_in(proj_succ, new_arity, ins);
 338                                         }
 339                                         else {
 340                                                 sched_remove(proj_succ);
 341                                                 kill_node(proj_succ);
 342                                         }
 343                                 }
 344                         }
 345
 346                         edges_reroute_kind(proj, pred, EDGE_KIND_NORMAL, irg);
 347                         edges_reroute_kind(proj, pred, EDGE_KIND_DEP, irg);
 348                 }
 349
 350                 /* the barrier also had the effect of a Keep for unused inputs.
 351                  * we now have to create an explicit Keep for them */
 352                 n_used = rbitset_popcount(used, arity);
 353                 if (n_used < (size_t) arity) {
 354                         int i;
 355
 356                         for (i = 0; i < arity; ++i) {
 357                                 ir_node *operand;
 358                                 if (rbitset_is_set(used, i))
 359                                         continue;
 360
 361                                 operand = get_irn_n(irn, i);
 362                                 keep_alive_barrier_operand(operand);
 363                         }
 364                 }
 365
 366                 kill_node_and_preds(irn);
 367                 break;
 368         }
 369 }
 370
 371 /**
 372  * Kill the Barrier nodes for better peephole optimization.
 373  */
 374 static void kill_barriers(ir_graph *irg)
 375 {
 376         ir_node *end_blk = get_irg_end_block(irg);
 377         ir_node *start_blk = get_irg_start_block(irg);
 378         int i;
 379
 380         /* skip the barrier on all return blocks */
 381         for (i = get_Block_n_cfgpreds(end_blk) - 1; i >= 0; --i) {
 382                 ir_node *be_ret = get_Block_cfgpred(end_blk, i);
 383                 ir_node *ret_blk = get_nodes_block(be_ret);
 384
 385                 if (ret_blk == start_blk)
 386                         continue;
 387
 388                 skip_barrier(ret_blk, irg);
 389         }
 390
 391         /* skip the barrier on the start block */
 392         start_blk = get_irg_start_block(irg);
 393         skip_barrier(start_blk, irg);
 394 }
 395
 396 /**
 397  * Check whether the node has only one user.  Explicitly ignore the anchor.
 398  */
 399 static int has_only_one_user(ir_node *node)
 400 {
 401         int              n = get_irn_n_edges(node);
 402         const ir_edge_t *edge;
 403
 404         if (n <= 1)
 405                 return 1;
 406
 407         if (n > 2)
 408                 return 0;
 409
 410         foreach_out_edge(node, edge) {
 411                 ir_node *src = get_edge_src_irn(edge);
 412                 if (is_Anchor(src))
 413                         return 1;
 414         }
 415
 416         return 0;
 417 }
 418
 419 /*
 420  * Tries to optimize a beIncSP node with its previous IncSP node.
 421  * Must be run from a be_peephole_opt() context.
 422  */
 423 ir_node *be_peephole_IncSP_IncSP(ir_node *node)
 424 {
 425         int      pred_offs;
 426         int      curr_offs;
 427         int      offs;
 428         ir_node *pred = be_get_IncSP_pred(node);
 429
 430         if (!be_is_IncSP(pred))
 431                 return node;
 432
 433         if (!has_only_one_user(pred))
 434                 return node;
 435
 436         pred_offs = be_get_IncSP_offset(pred);
 437         curr_offs = be_get_IncSP_offset(node);
 438
 439         if (pred_offs == BE_STACK_FRAME_SIZE_EXPAND) {
 440                 if (curr_offs != BE_STACK_FRAME_SIZE_SHRINK) {
 441                         return node;
 442                 }
 443                 offs = 0;
 444         } else if (pred_offs == BE_STACK_FRAME_SIZE_SHRINK) {
 445                 if (curr_offs != BE_STACK_FRAME_SIZE_EXPAND) {
 446                         return node;
 447                 }
 448                 offs = 0;
 449         } else if (curr_offs == BE_STACK_FRAME_SIZE_EXPAND ||
 450                    curr_offs == BE_STACK_FRAME_SIZE_SHRINK) {
 451                 return node;
 452         } else {
 453                 offs = curr_offs + pred_offs;
 454         }
 455
 456         /* add node offset to pred and remove our IncSP */
 457         be_set_IncSP_offset(pred, offs);
 458
 459         be_peephole_exchange(node, pred);
 460         return pred;
 461 }
 462
 463 void be_peephole_opt(ir_graph *irg)
 464 {
 465         unsigned  n_classes;
 466         unsigned  i;
 467
 468         /* barrier nodes are used for register allocations. They hinders
 469          * peephole optimizations, so remove them here. */
 470         kill_barriers(irg);
 471
 472         /* we sometimes find BadE nodes in float apps like optest_float.c or
 473          * kahansum.c for example... */
 474         be_liveness_invalidate(be_get_irg_liveness(irg));
 475         be_liveness_assure_sets(be_assure_liveness(irg));
 476
 477         arch_env = be_get_irg_arch_env(irg);
 478         lv       = be_get_irg_liveness(irg);
 479
 480         n_classes = arch_env->n_register_classes;
 481         register_values = XMALLOCN(ir_node**, n_classes);
 482         for (i = 0; i < n_classes; ++i) {
 483                 const arch_register_class_t *cls    = &arch_env->register_classes[i];
 484                 unsigned                     n_regs = arch_register_class_n_regs(cls);
 485                 register_values[i] = XMALLOCN(ir_node*, n_regs);
 486         }
 487
 488         irg_block_walk_graph(irg, process_block, NULL, NULL);
 489
 490         for (i = 0; i < n_classes; ++i) {
 491                 xfree(register_values[i]);
 492         }
 493         xfree(register_values);
 494 }
 495
 496 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_peephole);
 497 void be_init_peephole(void)
 498 {
 499         FIRM_DBG_REGISTER(dbg, "firm.be.peephole");
 500 }