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