gcc/tree-vectorizer.c

   1 /* Vectorizer
   2    Copyright (C) 2003-2013 Free Software Foundation, Inc.
   3    Contributed by Dorit Naishlos <dorit@il.ibm.com>
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify it under
   8 the terms of the GNU General Public License as published by the Free
   9 Software Foundation; either version 3, or (at your option) any later
  10 version.
  11
  12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15 for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GCC; see the file COPYING3.  If not see
  19 <http://www.gnu.org/licenses/>.  */
  20
  21 /* Loop and basic block vectorizer.
  22
  23   This file contains drivers for the three vectorizers:
  24   (1) loop vectorizer (inter-iteration parallelism),
  25   (2) loop-aware SLP (intra-iteration parallelism) (invoked by the loop
  26       vectorizer)
  27   (3) BB vectorizer (out-of-loops), aka SLP
  28
  29   The rest of the vectorizer's code is organized as follows:
  30   - tree-vect-loop.c - loop specific parts such as reductions, etc. These are
  31     used by drivers (1) and (2).
  32   - tree-vect-loop-manip.c - vectorizer's loop control-flow utilities, used by
  33     drivers (1) and (2).
  34   - tree-vect-slp.c - BB vectorization specific analysis and transformation,
  35     used by drivers (2) and (3).
  36   - tree-vect-stmts.c - statements analysis and transformation (used by all).
  37   - tree-vect-data-refs.c - vectorizer specific data-refs analysis and
  38     manipulations (used by all).
  39   - tree-vect-patterns.c - vectorizable code patterns detector (used by all)
  40
  41   Here's a poor attempt at illustrating that:
  42
  43      tree-vectorizer.c:
  44      loop_vect()  loop_aware_slp()  slp_vect()
  45           |        /           \          /
  46           |       /             \        /
  47           tree-vect-loop.c  tree-vect-slp.c
  48                 | \      \  /      /   |
  49                 |  \      \/      /    |
  50                 |   \     /\     /     |
  51                 |    \   /  \   /      |
  52          tree-vect-stmts.c  tree-vect-data-refs.c
  53                        \      /
  54                     tree-vect-patterns.c
  55 */
  56
  57 #include "config.h"
  58 #include "system.h"
  59 #include "coretypes.h"
  60 #include "dumpfile.h"
  61 #include "tm.h"
  62 #include "ggc.h"
  63 #include "tree.h"
  64 #include "stor-layout.h"
  65 #include "tree-pretty-print.h"
  66 #include "gimple.h"
  67 #include "gimple-iterator.h"
  68 #include "gimple-walk.h"
  69 #include "gimple-ssa.h"
  70 #include "cgraph.h"
  71 #include "tree-phinodes.h"
  72 #include "ssa-iterators.h"
  73 #include "tree-ssa-loop-manip.h"
  74 #include "cfgloop.h"
  75 #include "tree-vectorizer.h"
  76 #include "tree-pass.h"
  77 #include "hash-table.h"
  78 #include "tree-ssa-propagate.h"
  79 #include "dbgcnt.h"
  80
  81 /* Loop or bb location.  */
  82 LOC vect_location;
  83
  84 /* Vector mapping GIMPLE stmt to stmt_vec_info. */
  85 vec<vec_void_p> stmt_vec_info_vec;
  86 \f
  87 /* For mapping simduid to vectorization factor.  */
  88
  89 struct simduid_to_vf : typed_free_remove<simduid_to_vf>
  90 {
  91   unsigned int simduid;
  92   int vf;
  93
  94   /* hash_table support.  */
  95   typedef simduid_to_vf value_type;
  96   typedef simduid_to_vf compare_type;
  97   static inline hashval_t hash (const value_type *);
  98   static inline int equal (const value_type *, const compare_type *);
  99 };
 100
 101 inline hashval_t
 102 simduid_to_vf::hash (const value_type *p)
 103 {
 104   return p->simduid;
 105 }
 106
 107 inline int
 108 simduid_to_vf::equal (const value_type *p1, const value_type *p2)
 109 {
 110   return p1->simduid == p2->simduid;
 111 }
 112
 113 /* This hash maps the OMP simd array to the corresponding simduid used
 114    to index into it.  Like thus,
 115
 116         _7 = GOMP_SIMD_LANE (simduid.0)
 117         ...
 118         ...
 119         D.1737[_7] = stuff;
 120
 121
 122    This hash maps from the OMP simd array (D.1737[]) to DECL_UID of
 123    simduid.0.  */
 124
 125 struct simd_array_to_simduid : typed_free_remove<simd_array_to_simduid>
 126 {
 127   tree decl;
 128   unsigned int simduid;
 129
 130   /* hash_table support.  */
 131   typedef simd_array_to_simduid value_type;
 132   typedef simd_array_to_simduid compare_type;
 133   static inline hashval_t hash (const value_type *);
 134   static inline int equal (const value_type *, const compare_type *);
 135 };
 136
 137 inline hashval_t
 138 simd_array_to_simduid::hash (const value_type *p)
 139 {
 140   return DECL_UID (p->decl);
 141 }
 142
 143 inline int
 144 simd_array_to_simduid::equal (const value_type *p1, const value_type *p2)
 145 {
 146   return p1->decl == p2->decl;
 147 }
 148
 149 /* Fold IFN_GOMP_SIMD_LANE, IFN_GOMP_SIMD_VF and IFN_GOMP_SIMD_LAST_LANE
 150    into their corresponding constants.  */
 151
 152 static void
 153 adjust_simduid_builtins (hash_table <simduid_to_vf> &htab)
 154 {
 155   basic_block bb;
 156
 157   FOR_EACH_BB (bb)
 158     {
 159       gimple_stmt_iterator i;
 160
 161       for (i = gsi_start_bb (bb); !gsi_end_p (i); gsi_next (&i))
 162         {
 163           unsigned int vf = 1;
 164           enum internal_fn ifn;
 165           gimple stmt = gsi_stmt (i);
 166           tree t;
 167           if (!is_gimple_call (stmt)
 168               || !gimple_call_internal_p (stmt))
 169             continue;
 170           ifn = gimple_call_internal_fn (stmt);
 171           switch (ifn)
 172             {
 173             case IFN_GOMP_SIMD_LANE:
 174             case IFN_GOMP_SIMD_VF:
 175             case IFN_GOMP_SIMD_LAST_LANE:
 176               break;
 177             default:
 178               continue;
 179             }
 180           tree arg = gimple_call_arg (stmt, 0);
 181           gcc_assert (arg != NULL_TREE);
 182           gcc_assert (TREE_CODE (arg) == SSA_NAME);
 183           simduid_to_vf *p = NULL, data;
 184           data.simduid = DECL_UID (SSA_NAME_VAR (arg));
 185           if (htab.is_created ())
 186             p = htab.find (&data);
 187           if (p)
 188             vf = p->vf;
 189           switch (ifn)
 190             {
 191             case IFN_GOMP_SIMD_VF:
 192               t = build_int_cst (unsigned_type_node, vf);
 193               break;
 194             case IFN_GOMP_SIMD_LANE:
 195               t = build_int_cst (unsigned_type_node, 0);
 196               break;
 197             case IFN_GOMP_SIMD_LAST_LANE:
 198               t = gimple_call_arg (stmt, 1);
 199               break;
 200             default:
 201               gcc_unreachable ();
 202             }
 203           update_call_from_tree (&i, t);
 204         }
 205     }
 206 }
 207
 208 /* Helper structure for note_simd_array_uses.  */
 209
 210 struct note_simd_array_uses_struct
 211 {
 212   hash_table <simd_array_to_simduid> *htab;
 213   unsigned int simduid;
 214 };
 215
 216 /* Callback for note_simd_array_uses, called through walk_gimple_op.  */
 217
 218 static tree
 219 note_simd_array_uses_cb (tree *tp, int *walk_subtrees, void *data)
 220 {
 221   struct walk_stmt_info *wi = (struct walk_stmt_info *) data;
 222   struct note_simd_array_uses_struct *ns
 223     = (struct note_simd_array_uses_struct *) wi->info;
 224
 225   if (TYPE_P (*tp))
 226     *walk_subtrees = 0;
 227   else if (VAR_P (*tp)
 228            && lookup_attribute ("omp simd array", DECL_ATTRIBUTES (*tp))
 229            && DECL_CONTEXT (*tp) == current_function_decl)
 230     {
 231       simd_array_to_simduid data;
 232       if (!ns->htab->is_created ())
 233         ns->htab->create (15);
 234       data.decl = *tp;
 235       data.simduid = ns->simduid;
 236       simd_array_to_simduid **slot = ns->htab->find_slot (&data, INSERT);
 237       if (*slot == NULL)
 238         {
 239           simd_array_to_simduid *p = XNEW (simd_array_to_simduid);
 240           *p = data;
 241           *slot = p;
 242         }
 243       else if ((*slot)->simduid != ns->simduid)
 244         (*slot)->simduid = -1U;
 245       *walk_subtrees = 0;
 246     }
 247   return NULL_TREE;
 248 }
 249
 250 /* Find "omp simd array" temporaries and map them to corresponding
 251    simduid.  */
 252
 253 static void
 254 note_simd_array_uses (hash_table <simd_array_to_simduid> *htab)
 255 {
 256   basic_block bb;
 257   gimple_stmt_iterator gsi;
 258   struct walk_stmt_info wi;
 259   struct note_simd_array_uses_struct ns;
 260
 261   memset (&wi, 0, sizeof (wi));
 262   wi.info = &ns;
 263   ns.htab = htab;
 264
 265   FOR_EACH_BB (bb)
 266     for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
 267       {
 268         gimple stmt = gsi_stmt (gsi);
 269         if (!is_gimple_call (stmt) || !gimple_call_internal_p (stmt))
 270           continue;
 271         switch (gimple_call_internal_fn (stmt))
 272           {
 273           case IFN_GOMP_SIMD_LANE:
 274           case IFN_GOMP_SIMD_VF:
 275           case IFN_GOMP_SIMD_LAST_LANE:
 276             break;
 277           default:
 278             continue;
 279           }
 280         tree lhs = gimple_call_lhs (stmt);
 281         if (lhs == NULL_TREE)
 282           continue;
 283         imm_use_iterator use_iter;
 284         gimple use_stmt;
 285         ns.simduid = DECL_UID (SSA_NAME_VAR (gimple_call_arg (stmt, 0)));
 286         FOR_EACH_IMM_USE_STMT (use_stmt, use_iter, lhs)
 287           if (!is_gimple_debug (use_stmt))
 288             walk_gimple_op (use_stmt, note_simd_array_uses_cb, &wi);
 289       }
 290 }
 291 \f
 292 /* A helper function to free data refs.  */
 293
 294 void
 295 vect_destroy_datarefs (loop_vec_info loop_vinfo, bb_vec_info bb_vinfo)
 296 {
 297   vec<data_reference_p> datarefs;
 298   struct data_reference *dr;
 299   unsigned int i;
 300
 301  if (loop_vinfo)
 302     datarefs = LOOP_VINFO_DATAREFS (loop_vinfo);
 303   else
 304     datarefs = BB_VINFO_DATAREFS (bb_vinfo);
 305
 306   FOR_EACH_VEC_ELT (datarefs, i, dr)
 307     if (dr->aux)
 308       {
 309         free (dr->aux);
 310         dr->aux = NULL;
 311       }
 312
 313   free_data_refs (datarefs);
 314 }
 315
 316
 317 /* Function vectorize_loops.
 318
 319    Entry point to loop vectorization phase.  */
 320
 321 unsigned
 322 vectorize_loops (void)
 323 {
 324   unsigned int i;
 325   unsigned int num_vectorized_loops = 0;
 326   unsigned int vect_loops_num;
 327   struct loop *loop;
 328   hash_table <simduid_to_vf> simduid_to_vf_htab;
 329   hash_table <simd_array_to_simduid> simd_array_to_simduid_htab;
 330
 331   vect_loops_num = number_of_loops (cfun);
 332
 333   /* Bail out if there are no loops.  */
 334   if (vect_loops_num <= 1)
 335     {
 336       if (cfun->has_simduid_loops)
 337         adjust_simduid_builtins (simduid_to_vf_htab);
 338       return 0;
 339     }
 340
 341   if (cfun->has_simduid_loops)
 342     note_simd_array_uses (&simd_array_to_simduid_htab);
 343
 344   init_stmt_vec_info_vec ();
 345
 346   /*  ----------- Analyze loops. -----------  */
 347
 348   /* If some loop was duplicated, it gets bigger number
 349      than all previously defined loops.  This fact allows us to run
 350      only over initial loops skipping newly generated ones.  */
 351   FOR_EACH_LOOP (loop, 0)
 352     if ((flag_tree_loop_vectorize && optimize_loop_nest_for_speed_p (loop))
 353         || loop->force_vect)
 354       {
 355         loop_vec_info loop_vinfo;
 356         vect_location = find_loop_location (loop);
 357         if (LOCATION_LOCUS (vect_location) != UNKNOWN_LOC
 358             && dump_enabled_p ())
 359           dump_printf (MSG_NOTE, "\nAnalyzing loop at %s:%d\n",
 360                        LOC_FILE (vect_location), LOC_LINE (vect_location));
 361
 362         loop_vinfo = vect_analyze_loop (loop);
 363         loop->aux = loop_vinfo;
 364
 365         if (!loop_vinfo || !LOOP_VINFO_VECTORIZABLE_P (loop_vinfo))
 366           continue;
 367
 368         if (!dbg_cnt (vect_loop))
 369           break;
 370
 371         if (LOCATION_LOCUS (vect_location) != UNKNOWN_LOC
 372             && dump_enabled_p ())
 373           dump_printf_loc (MSG_OPTIMIZED_LOCATIONS, vect_location,
 374                            "loop vectorized\n");
 375         vect_transform_loop (loop_vinfo);
 376         num_vectorized_loops++;
 377         /* Now that the loop has been vectorized, allow it to be unrolled
 378            etc.  */
 379         loop->force_vect = false;
 380
 381         if (loop->simduid)
 382           {
 383             simduid_to_vf *simduid_to_vf_data = XNEW (simduid_to_vf);
 384             if (!simduid_to_vf_htab.is_created ())
 385               simduid_to_vf_htab.create (15);
 386             simduid_to_vf_data->simduid = DECL_UID (loop->simduid);
 387             simduid_to_vf_data->vf = loop_vinfo->vectorization_factor;
 388             *simduid_to_vf_htab.find_slot (simduid_to_vf_data, INSERT)
 389               = simduid_to_vf_data;
 390           }
 391       }
 392
 393   vect_location = UNKNOWN_LOC;
 394
 395   statistics_counter_event (cfun, "Vectorized loops", num_vectorized_loops);
 396   if (dump_enabled_p ()
 397       || (num_vectorized_loops > 0 && dump_enabled_p ()))
 398     dump_printf_loc (MSG_NOTE, vect_location,
 399                      "vectorized %u loops in function.\n",
 400                      num_vectorized_loops);
 401
 402   /*  ----------- Finalize. -----------  */
 403
 404   for (i = 1; i < vect_loops_num; i++)
 405     {
 406       loop_vec_info loop_vinfo;
 407
 408       loop = get_loop (cfun, i);
 409       if (!loop)
 410         continue;
 411       loop_vinfo = (loop_vec_info) loop->aux;
 412       destroy_loop_vec_info (loop_vinfo, true);
 413       loop->aux = NULL;
 414     }
 415
 416   free_stmt_vec_info_vec ();
 417
 418   /* Fold IFN_GOMP_SIMD_{VF,LANE,LAST_LANE} builtins.  */
 419   if (cfun->has_simduid_loops)
 420     adjust_simduid_builtins (simduid_to_vf_htab);
 421
 422   /* Shrink any "omp array simd" temporary arrays to the
 423      actual vectorization factors.  */
 424   if (simd_array_to_simduid_htab.is_created ())
 425     {
 426       for (hash_table <simd_array_to_simduid>::iterator iter
 427            = simd_array_to_simduid_htab.begin ();
 428            iter != simd_array_to_simduid_htab.end (); ++iter)
 429         if ((*iter).simduid != -1U)
 430           {
 431             tree decl = (*iter).decl;
 432             int vf = 1;
 433             if (simduid_to_vf_htab.is_created ())
 434               {
 435                 simduid_to_vf *p = NULL, data;
 436                 data.simduid = (*iter).simduid;
 437                 p = simduid_to_vf_htab.find (&data);
 438                 if (p)
 439                   vf = p->vf;
 440               }
 441             tree atype
 442               = build_array_type_nelts (TREE_TYPE (TREE_TYPE (decl)), vf);
 443             TREE_TYPE (decl) = atype;
 444             relayout_decl (decl);
 445           }
 446
 447       simd_array_to_simduid_htab.dispose ();
 448     }
 449   if (simduid_to_vf_htab.is_created ())
 450     simduid_to_vf_htab.dispose ();
 451
 452   if (num_vectorized_loops > 0)
 453     {
 454       /* If we vectorized any loop only virtual SSA form needs to be updated.
 455          ???  Also while we try hard to update loop-closed SSA form we fail
 456          to properly do this in some corner-cases (see PR56286).  */
 457       rewrite_into_loop_closed_ssa (NULL, TODO_update_ssa_only_virtuals);
 458       return TODO_cleanup_cfg;
 459     }
 460
 461   return 0;
 462 }
 463
 464
 465 /*  Entry point to basic block SLP phase.  */
 466
 467 static unsigned int
 468 execute_vect_slp (void)
 469 {
 470   basic_block bb;
 471
 472   init_stmt_vec_info_vec ();
 473
 474   FOR_EACH_BB (bb)
 475     {
 476       vect_location = find_bb_location (bb);
 477
 478       if (vect_slp_analyze_bb (bb))
 479         {
 480           if (!dbg_cnt (vect_slp))
 481             break;
 482
 483           vect_slp_transform_bb (bb);
 484           if (dump_enabled_p ())
 485             dump_printf_loc (MSG_OPTIMIZED_LOCATIONS, vect_location,
 486                              "basic block vectorized\n");
 487         }
 488     }
 489
 490   free_stmt_vec_info_vec ();
 491   return 0;
 492 }
 493
 494 static bool
 495 gate_vect_slp (void)
 496 {
 497   return flag_tree_slp_vectorize != 0;
 498 }
 499
 500 namespace {
 501
 502 const pass_data pass_data_slp_vectorize =
 503 {
 504   GIMPLE_PASS, /* type */
 505   "slp", /* name */
 506   OPTGROUP_LOOP | OPTGROUP_VEC, /* optinfo_flags */
 507   true, /* has_gate */
 508   true, /* has_execute */
 509   TV_TREE_SLP_VECTORIZATION, /* tv_id */
 510   ( PROP_ssa | PROP_cfg ), /* properties_required */
 511   0, /* properties_provided */
 512   0, /* properties_destroyed */
 513   0, /* todo_flags_start */
 514   ( TODO_verify_ssa | TODO_update_ssa
 515     | TODO_verify_stmts ), /* todo_flags_finish */
 516 };
 517
 518 class pass_slp_vectorize : public gimple_opt_pass
 519 {
 520 public:
 521   pass_slp_vectorize (gcc::context *ctxt)
 522     : gimple_opt_pass (pass_data_slp_vectorize, ctxt)
 523   {}
 524
 525   /* opt_pass methods: */
 526   bool gate () { return gate_vect_slp (); }
 527   unsigned int execute () { return execute_vect_slp (); }
 528
 529 }; // class pass_slp_vectorize
 530
 531 } // anon namespace
 532
 533 gimple_opt_pass *
 534 make_pass_slp_vectorize (gcc::context *ctxt)
 535 {
 536   return new pass_slp_vectorize (ctxt);
 537 }
 538
 539
 540 /* Increase alignment of global arrays to improve vectorization potential.
 541    TODO:
 542    - Consider also structs that have an array field.
 543    - Use ipa analysis to prune arrays that can't be vectorized?
 544      This should involve global alignment analysis and in the future also
 545      array padding.  */
 546
 547 static unsigned int
 548 increase_alignment (void)
 549 {
 550   struct varpool_node *vnode;
 551
 552   vect_location = UNKNOWN_LOC;
 553
 554   /* Increase the alignment of all global arrays for vectorization.  */
 555   FOR_EACH_DEFINED_VARIABLE (vnode)
 556     {
 557       tree vectype, decl = vnode->decl;
 558       tree t;
 559       unsigned int alignment;
 560
 561       t = TREE_TYPE (decl);
 562       if (TREE_CODE (t) != ARRAY_TYPE)
 563         continue;
 564       vectype = get_vectype_for_scalar_type (strip_array_types (t));
 565       if (!vectype)
 566         continue;
 567       alignment = TYPE_ALIGN (vectype);
 568       if (DECL_ALIGN (decl) >= alignment)
 569         continue;
 570
 571       if (vect_can_force_dr_alignment_p (decl, alignment))
 572         {
 573           DECL_ALIGN (decl) = TYPE_ALIGN (vectype);
 574           DECL_USER_ALIGN (decl) = 1;
 575           dump_printf (MSG_NOTE, "Increasing alignment of decl: ");
 576           dump_generic_expr (MSG_NOTE, TDF_SLIM, decl);
 577           dump_printf (MSG_NOTE, "\n");
 578         }
 579     }
 580   return 0;
 581 }
 582
 583
 584 static bool
 585 gate_increase_alignment (void)
 586 {
 587   return flag_section_anchors && flag_tree_loop_vectorize;
 588 }
 589
 590
 591 namespace {
 592
 593 const pass_data pass_data_ipa_increase_alignment =
 594 {
 595   SIMPLE_IPA_PASS, /* type */
 596   "increase_alignment", /* name */
 597   OPTGROUP_LOOP | OPTGROUP_VEC, /* optinfo_flags */
 598   true, /* has_gate */
 599   true, /* has_execute */
 600   TV_IPA_OPT, /* tv_id */
 601   0, /* properties_required */
 602   0, /* properties_provided */
 603   0, /* properties_destroyed */
 604   0, /* todo_flags_start */
 605   0, /* todo_flags_finish */
 606 };
 607
 608 class pass_ipa_increase_alignment : public simple_ipa_opt_pass
 609 {
 610 public:
 611   pass_ipa_increase_alignment (gcc::context *ctxt)
 612     : simple_ipa_opt_pass (pass_data_ipa_increase_alignment, ctxt)
 613   {}
 614
 615   /* opt_pass methods: */
 616   bool gate () { return gate_increase_alignment (); }
 617   unsigned int execute () { return increase_alignment (); }
 618
 619 }; // class pass_ipa_increase_alignment
 620
 621 } // anon namespace
 622
 623 simple_ipa_opt_pass *
 624 make_pass_ipa_increase_alignment (gcc::context *ctxt)
 625 {
 626   return new pass_ipa_increase_alignment (ctxt);
 627 }