gcc/tree-vectorizer.c

   1 /* Vectorizer
   2    Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
   3    Free Software Foundation, Inc.
   4    Contributed by Dorit Naishlos <dorit@il.ibm.com>
   5
   6 This file is part of GCC.
   7
   8 GCC is free software; you can redistribute it and/or modify it under
   9 the terms of the GNU General Public License as published by the Free
  10 Software Foundation; either version 3, or (at your option) any later
  11 version.
  12
  13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  15 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  16 for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with GCC; see the file COPYING3.  If not see
  20 <http://www.gnu.org/licenses/>.  */
  21
  22 /* Loop and basic block vectorizer.
  23
  24   This file contains drivers for the three vectorizers:
  25   (1) loop vectorizer (inter-iteration parallelism),
  26   (2) loop-aware SLP (intra-iteration parallelism) (invoked by the loop
  27       vectorizer)
  28   (3) BB vectorizer (out-of-loops), aka SLP
  29
  30   The rest of the vectorizer's code is organized as follows:
  31   - tree-vect-loop.c - loop specific parts such as reductions, etc. These are
  32     used by drivers (1) and (2).
  33   - tree-vect-loop-manip.c - vectorizer's loop control-flow utilities, used by
  34     drivers (1) and (2).
  35   - tree-vect-slp.c - BB vectorization specific analysis and transformation,
  36     used by drivers (2) and (3).
  37   - tree-vect-stmts.c - statements analysis and transformation (used by all).
  38   - tree-vect-data-refs.c - vectorizer specific data-refs analysis and
  39     manipulations (used by all).
  40   - tree-vect-patterns.c - vectorizable code patterns detector (used by all)
  41
  42   Here's a poor attempt at illustrating that:
  43
  44      tree-vectorizer.c:
  45      loop_vect()  loop_aware_slp()  slp_vect()
  46           |        /           \          /
  47           |       /             \        /
  48           tree-vect-loop.c  tree-vect-slp.c
  49                 | \      \  /      /   |
  50                 |  \      \/      /    |
  51                 |   \     /\     /     |
  52                 |    \   /  \   /      |
  53          tree-vect-stmts.c  tree-vect-data-refs.c
  54                        \      /
  55                     tree-vect-patterns.c
  56 */
  57
  58 #include "config.h"
  59 #include "system.h"
  60 #include "coretypes.h"
  61 #include "tm.h"
  62 #include "ggc.h"
  63 #include "tree.h"
  64 #include "tree-pretty-print.h"
  65 #include "tree-flow.h"
  66 #include "tree-dump.h"
  67 #include "cfgloop.h"
  68 #include "cfglayout.h"
  69 #include "tree-vectorizer.h"
  70 #include "tree-pass.h"
  71 #include "timevar.h"
  72
  73 /* vect_dump will be set to stderr or dump_file if exist.  */
  74 FILE *vect_dump;
  75
  76 /* vect_verbosity_level set to an invalid value
  77    to mark that it's uninitialized.  */
  78 static enum verbosity_levels vect_verbosity_level = MAX_VERBOSITY_LEVEL;
  79 static enum verbosity_levels user_vect_verbosity_level = MAX_VERBOSITY_LEVEL;
  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,heap) *stmt_vec_info_vec;
  86
  87 \f
  88
  89 /* Function vect_set_verbosity_level.
  90
  91    Called from opts.c upon detection of the
  92    -ftree-vectorizer-verbose=N option.  */
  93
  94 void
  95 vect_set_verbosity_level (const char *val)
  96 {
  97    unsigned int vl;
  98
  99    vl = atoi (val);
 100    if (vl < MAX_VERBOSITY_LEVEL)
 101      user_vect_verbosity_level = (enum verbosity_levels) vl;
 102    else
 103      user_vect_verbosity_level
 104       = (enum verbosity_levels) (MAX_VERBOSITY_LEVEL - 1);
 105 }
 106
 107
 108 /* Function vect_set_dump_settings.
 109
 110    Fix the verbosity level of the vectorizer if the
 111    requested level was not set explicitly using the flag
 112    -ftree-vectorizer-verbose=N.
 113    Decide where to print the debugging information (dump_file/stderr).
 114    If the user defined the verbosity level, but there is no dump file,
 115    print to stderr, otherwise print to the dump file.  */
 116
 117 static void
 118 vect_set_dump_settings (bool slp)
 119 {
 120   vect_dump = dump_file;
 121
 122   /* Check if the verbosity level was defined by the user:  */
 123   if (user_vect_verbosity_level != MAX_VERBOSITY_LEVEL)
 124     {
 125       vect_verbosity_level = user_vect_verbosity_level;
 126       /* Ignore user defined verbosity if dump flags require higher level of
 127          verbosity.  */
 128       if (dump_file)
 129         {
 130           if (((dump_flags & TDF_DETAILS)
 131                 && vect_verbosity_level >= REPORT_DETAILS)
 132                || ((dump_flags & TDF_STATS)
 133                     && vect_verbosity_level >= REPORT_UNVECTORIZED_LOCATIONS))
 134             return;
 135         }
 136       else
 137         {
 138           /* If there is no dump file, print to stderr in case of loop
 139              vectorization.  */
 140           if (!slp)
 141             vect_dump = stderr;
 142
 143           return;
 144         }
 145     }
 146
 147   /* User didn't specify verbosity level:  */
 148   if (dump_file && (dump_flags & TDF_DETAILS))
 149     vect_verbosity_level = REPORT_DETAILS;
 150   else if (dump_file && (dump_flags & TDF_STATS))
 151     vect_verbosity_level = REPORT_UNVECTORIZED_LOCATIONS;
 152   else
 153     vect_verbosity_level = REPORT_NONE;
 154
 155   gcc_assert (dump_file || vect_verbosity_level == REPORT_NONE);
 156 }
 157
 158
 159 /* Function debug_loop_details.
 160
 161    For vectorization debug dumps.  */
 162
 163 bool
 164 vect_print_dump_info (enum verbosity_levels vl)
 165 {
 166   if (vl > vect_verbosity_level)
 167     return false;
 168
 169   if (!current_function_decl || !vect_dump)
 170     return false;
 171
 172   if (vect_location == UNKNOWN_LOC)
 173     fprintf (vect_dump, "\n%s:%d: note: ",
 174              DECL_SOURCE_FILE (current_function_decl),
 175              DECL_SOURCE_LINE (current_function_decl));
 176   else
 177     fprintf (vect_dump, "\n%s:%d: note: ",
 178              LOC_FILE (vect_location), LOC_LINE (vect_location));
 179
 180   return true;
 181 }
 182
 183
 184 /* Function vectorize_loops.
 185
 186    Entry point to loop vectorization phase.  */
 187
 188 unsigned
 189 vectorize_loops (void)
 190 {
 191   unsigned int i;
 192   unsigned int num_vectorized_loops = 0;
 193   unsigned int vect_loops_num;
 194   loop_iterator li;
 195   struct loop *loop;
 196
 197   vect_loops_num = number_of_loops ();
 198
 199   /* Bail out if there are no loops.  */
 200   if (vect_loops_num <= 1)
 201     return 0;
 202
 203   /* Fix the verbosity level if not defined explicitly by the user.  */
 204   vect_set_dump_settings (false);
 205
 206   init_stmt_vec_info_vec ();
 207
 208   /*  ----------- Analyze loops. -----------  */
 209
 210   /* If some loop was duplicated, it gets bigger number
 211      than all previously defined loops.  This fact allows us to run
 212      only over initial loops skipping newly generated ones.  */
 213   FOR_EACH_LOOP (li, loop, 0)
 214     if (optimize_loop_nest_for_speed_p (loop))
 215       {
 216         loop_vec_info loop_vinfo;
 217
 218         vect_location = find_loop_location (loop);
 219         loop_vinfo = vect_analyze_loop (loop);
 220         loop->aux = loop_vinfo;
 221
 222         if (!loop_vinfo || !LOOP_VINFO_VECTORIZABLE_P (loop_vinfo))
 223           continue;
 224
 225         vect_transform_loop (loop_vinfo);
 226         num_vectorized_loops++;
 227       }
 228
 229   vect_location = UNKNOWN_LOC;
 230
 231   statistics_counter_event (cfun, "Vectorized loops", num_vectorized_loops);
 232   if (vect_print_dump_info (REPORT_UNVECTORIZED_LOCATIONS)
 233       || (num_vectorized_loops > 0
 234           && vect_print_dump_info (REPORT_VECTORIZED_LOCATIONS)))
 235     fprintf (vect_dump, "vectorized %u loops in function.\n",
 236              num_vectorized_loops);
 237
 238   /*  ----------- Finalize. -----------  */
 239
 240   mark_sym_for_renaming (gimple_vop (cfun));
 241
 242   for (i = 1; i < vect_loops_num; i++)
 243     {
 244       loop_vec_info loop_vinfo;
 245
 246       loop = get_loop (i);
 247       if (!loop)
 248         continue;
 249       loop_vinfo = (loop_vec_info) loop->aux;
 250       destroy_loop_vec_info (loop_vinfo, true);
 251       loop->aux = NULL;
 252     }
 253
 254   free_stmt_vec_info_vec ();
 255
 256   return num_vectorized_loops > 0 ? TODO_cleanup_cfg : 0;
 257 }
 258
 259
 260 /*  Entry point to basic block SLP phase.  */
 261
 262 static unsigned int
 263 execute_vect_slp (void)
 264 {
 265   basic_block bb;
 266
 267   /* Fix the verbosity level if not defined explicitly by the user.  */
 268   vect_set_dump_settings (true);
 269
 270   init_stmt_vec_info_vec ();
 271
 272   FOR_EACH_BB (bb)
 273     {
 274       vect_location = find_bb_location (bb);
 275
 276       if (vect_slp_analyze_bb (bb))
 277         {
 278           vect_slp_transform_bb (bb);
 279
 280           if (vect_print_dump_info (REPORT_VECTORIZED_LOCATIONS))
 281             fprintf (vect_dump, "basic block vectorized using SLP\n");
 282         }
 283     }
 284
 285   free_stmt_vec_info_vec ();
 286   return 0;
 287 }
 288
 289 static bool
 290 gate_vect_slp (void)
 291 {
 292   /* Apply SLP either if the vectorizer is on and the user didn't specify
 293      whether to run SLP or not, or if the SLP flag was set by the user.  */
 294   return ((flag_tree_vectorize != 0 && flag_tree_slp_vectorize != 0)
 295           || flag_tree_slp_vectorize == 1);
 296 }
 297
 298 struct gimple_opt_pass pass_slp_vectorize =
 299 {
 300  {
 301   GIMPLE_PASS,
 302   "slp",                                /* name */
 303   gate_vect_slp,                        /* gate */
 304   execute_vect_slp,                     /* execute */
 305   NULL,                                 /* sub */
 306   NULL,                                 /* next */
 307   0,                                    /* static_pass_number */
 308   TV_TREE_SLP_VECTORIZATION,            /* tv_id */
 309   PROP_ssa | PROP_cfg,                  /* properties_required */
 310   0,                                    /* properties_provided */
 311   0,                                    /* properties_destroyed */
 312   0,                                    /* todo_flags_start */
 313   TODO_ggc_collect
 314     | TODO_verify_ssa
 315     | TODO_dump_func
 316     | TODO_update_ssa
 317     | TODO_verify_stmts                 /* todo_flags_finish */
 318  }
 319 };
 320
 321
 322 /* Increase alignment of global arrays to improve vectorization potential.
 323    TODO:
 324    - Consider also structs that have an array field.
 325    - Use ipa analysis to prune arrays that can't be vectorized?
 326      This should involve global alignment analysis and in the future also
 327      array padding.  */
 328
 329 static unsigned int
 330 increase_alignment (void)
 331 {
 332   struct varpool_node *vnode;
 333
 334   /* Increase the alignment of all global arrays for vectorization.  */
 335   for (vnode = varpool_nodes_queue;
 336        vnode;
 337        vnode = vnode->next_needed)
 338     {
 339       tree vectype, decl = vnode->decl;
 340       tree t;
 341       unsigned int alignment;
 342
 343       t = TREE_TYPE(decl);
 344       if (TREE_CODE (t) != ARRAY_TYPE)
 345         continue;
 346       vectype = get_vectype_for_scalar_type (strip_array_types (t));
 347       if (!vectype)
 348         continue;
 349       alignment = TYPE_ALIGN (vectype);
 350       if (DECL_ALIGN (decl) >= alignment)
 351         continue;
 352
 353       if (vect_can_force_dr_alignment_p (decl, alignment))
 354         {
 355           DECL_ALIGN (decl) = TYPE_ALIGN (vectype);
 356           DECL_USER_ALIGN (decl) = 1;
 357           if (dump_file)
 358             {
 359               fprintf (dump_file, "Increasing alignment of decl: ");
 360               print_generic_expr (dump_file, decl, TDF_SLIM);
 361               fprintf (dump_file, "\n");
 362             }
 363         }
 364     }
 365   return 0;
 366 }
 367
 368
 369 static bool
 370 gate_increase_alignment (void)
 371 {
 372   return flag_section_anchors && flag_tree_vectorize;
 373 }
 374
 375
 376 struct simple_ipa_opt_pass pass_ipa_increase_alignment =
 377 {
 378  {
 379   SIMPLE_IPA_PASS,
 380   "increase_alignment",                 /* name */
 381   gate_increase_alignment,              /* gate */
 382   increase_alignment,                   /* execute */
 383   NULL,                                 /* sub */
 384   NULL,                                 /* next */
 385   0,                                    /* static_pass_number */
 386   TV_NONE,                              /* tv_id */
 387   0,                                    /* properties_required */
 388   0,                                    /* properties_provided */
 389   0,                                    /* properties_destroyed */
 390   0,                                    /* todo_flags_start */
 391   0                                     /* todo_flags_finish */
 392  }
 393 };