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 vect_verbosity_levels vect_verbosity_level = MAX_VERBOSITY_LEVEL;
  79
  80 /* Loop or bb location.  */
  81 LOC vect_location;
  82
  83 /* Vector mapping GIMPLE stmt to stmt_vec_info. */
  84 VEC(vec_void_p,heap) *stmt_vec_info_vec;
  85
  86 \f
  87
  88 /* Function vect_set_dump_settings.
  89
  90    Fix the verbosity level of the vectorizer if the
  91    requested level was not set explicitly using the flag
  92    -ftree-vectorizer-verbose=N.
  93    Decide where to print the debugging information (dump_file/stderr).
  94    If the user defined the verbosity level, but there is no dump file,
  95    print to stderr, otherwise print to the dump file.  */
  96
  97 static void
  98 vect_set_dump_settings (bool slp)
  99 {
 100   vect_dump = dump_file;
 101
 102   /* Check if the verbosity level was defined by the user:  */
 103   if (user_vect_verbosity_level != MAX_VERBOSITY_LEVEL)
 104     {
 105       vect_verbosity_level = user_vect_verbosity_level;
 106       /* Ignore user defined verbosity if dump flags require higher level of
 107          verbosity.  */
 108       if (dump_file)
 109         {
 110           if (((dump_flags & TDF_DETAILS)
 111                 && vect_verbosity_level >= REPORT_DETAILS)
 112                || ((dump_flags & TDF_STATS)
 113                     && vect_verbosity_level >= REPORT_UNVECTORIZED_LOCATIONS))
 114             return;
 115         }
 116       else
 117         {
 118           /* If there is no dump file, print to stderr in case of loop
 119              vectorization.  */
 120           if (!slp)
 121             vect_dump = stderr;
 122
 123           return;
 124         }
 125     }
 126
 127   /* User didn't specify verbosity level:  */
 128   if (dump_file && (dump_flags & TDF_DETAILS))
 129     vect_verbosity_level = REPORT_DETAILS;
 130   else if (dump_file && (dump_flags & TDF_STATS))
 131     vect_verbosity_level = REPORT_UNVECTORIZED_LOCATIONS;
 132   else
 133     vect_verbosity_level = REPORT_NONE;
 134
 135   gcc_assert (dump_file || vect_verbosity_level == REPORT_NONE);
 136 }
 137
 138
 139 /* Function debug_loop_details.
 140
 141    For vectorization debug dumps.  */
 142
 143 bool
 144 vect_print_dump_info (enum vect_verbosity_levels vl)
 145 {
 146   if (vl > vect_verbosity_level)
 147     return false;
 148
 149   if (!current_function_decl || !vect_dump)
 150     return false;
 151
 152   if (vect_location == UNKNOWN_LOC)
 153     fprintf (vect_dump, "\n%s:%d: note: ",
 154              DECL_SOURCE_FILE (current_function_decl),
 155              DECL_SOURCE_LINE (current_function_decl));
 156   else
 157     fprintf (vect_dump, "\n%d: ", LOC_LINE (vect_location));
 158
 159   return true;
 160 }
 161
 162
 163 /* Function vectorize_loops.
 164
 165    Entry point to loop vectorization phase.  */
 166
 167 unsigned
 168 vectorize_loops (void)
 169 {
 170   unsigned int i;
 171   unsigned int num_vectorized_loops = 0;
 172   unsigned int vect_loops_num;
 173   loop_iterator li;
 174   struct loop *loop;
 175
 176   vect_loops_num = number_of_loops ();
 177
 178   /* Bail out if there are no loops.  */
 179   if (vect_loops_num <= 1)
 180     return 0;
 181
 182   /* Fix the verbosity level if not defined explicitly by the user.  */
 183   vect_set_dump_settings (false);
 184
 185   init_stmt_vec_info_vec ();
 186
 187   /*  ----------- Analyze loops. -----------  */
 188
 189   /* If some loop was duplicated, it gets bigger number
 190      than all previously defined loops.  This fact allows us to run
 191      only over initial loops skipping newly generated ones.  */
 192   FOR_EACH_LOOP (li, loop, 0)
 193     if (optimize_loop_nest_for_speed_p (loop))
 194       {
 195         loop_vec_info loop_vinfo;
 196
 197         vect_location = find_loop_location (loop);
 198         if (vect_location != UNKNOWN_LOC
 199             && vect_verbosity_level > REPORT_NONE)
 200           fprintf (vect_dump, "\nAnalyzing loop at %s:%d\n",
 201             LOC_FILE (vect_location), LOC_LINE (vect_location));
 202
 203         loop_vinfo = vect_analyze_loop (loop);
 204         loop->aux = loop_vinfo;
 205
 206         if (!loop_vinfo || !LOOP_VINFO_VECTORIZABLE_P (loop_vinfo))
 207           continue;
 208
 209         if (vect_location != UNKNOWN_LOC
 210             && vect_verbosity_level > REPORT_NONE)
 211           fprintf (vect_dump, "\n\nVectorizing loop at %s:%d\n",
 212             LOC_FILE (vect_location), LOC_LINE (vect_location));
 213
 214         vect_transform_loop (loop_vinfo);
 215         num_vectorized_loops++;
 216       }
 217
 218   vect_location = UNKNOWN_LOC;
 219
 220   statistics_counter_event (cfun, "Vectorized loops", num_vectorized_loops);
 221   if (vect_print_dump_info (REPORT_UNVECTORIZED_LOCATIONS)
 222       || (num_vectorized_loops > 0
 223           && vect_print_dump_info (REPORT_VECTORIZED_LOCATIONS)))
 224     fprintf (vect_dump, "vectorized %u loops in function.\n",
 225              num_vectorized_loops);
 226
 227   /*  ----------- Finalize. -----------  */
 228
 229   mark_sym_for_renaming (gimple_vop (cfun));
 230
 231   for (i = 1; i < vect_loops_num; i++)
 232     {
 233       loop_vec_info loop_vinfo;
 234
 235       loop = get_loop (i);
 236       if (!loop)
 237         continue;
 238       loop_vinfo = (loop_vec_info) loop->aux;
 239       destroy_loop_vec_info (loop_vinfo, true);
 240       loop->aux = NULL;
 241     }
 242
 243   free_stmt_vec_info_vec ();
 244
 245   return num_vectorized_loops > 0 ? TODO_cleanup_cfg : 0;
 246 }
 247
 248
 249 /*  Entry point to basic block SLP phase.  */
 250
 251 static unsigned int
 252 execute_vect_slp (void)
 253 {
 254   basic_block bb;
 255
 256   /* Fix the verbosity level if not defined explicitly by the user.  */
 257   vect_set_dump_settings (true);
 258
 259   init_stmt_vec_info_vec ();
 260
 261   FOR_EACH_BB (bb)
 262     {
 263       vect_location = find_bb_location (bb);
 264
 265       if (vect_slp_analyze_bb (bb))
 266         {
 267           vect_slp_transform_bb (bb);
 268
 269           if (vect_print_dump_info (REPORT_VECTORIZED_LOCATIONS))
 270             fprintf (vect_dump, "basic block vectorized using SLP\n");
 271         }
 272     }
 273
 274   free_stmt_vec_info_vec ();
 275   return 0;
 276 }
 277
 278 static bool
 279 gate_vect_slp (void)
 280 {
 281   /* Apply SLP either if the vectorizer is on and the user didn't specify
 282      whether to run SLP or not, or if the SLP flag was set by the user.  */
 283   return ((flag_tree_vectorize != 0 && flag_tree_slp_vectorize != 0)
 284           || flag_tree_slp_vectorize == 1);
 285 }
 286
 287 struct gimple_opt_pass pass_slp_vectorize =
 288 {
 289  {
 290   GIMPLE_PASS,
 291   "slp",                                /* name */
 292   gate_vect_slp,                        /* gate */
 293   execute_vect_slp,                     /* execute */
 294   NULL,                                 /* sub */
 295   NULL,                                 /* next */
 296   0,                                    /* static_pass_number */
 297   TV_TREE_SLP_VECTORIZATION,            /* tv_id */
 298   PROP_ssa | PROP_cfg,                  /* properties_required */
 299   0,                                    /* properties_provided */
 300   0,                                    /* properties_destroyed */
 301   0,                                    /* todo_flags_start */
 302   TODO_ggc_collect
 303     | TODO_verify_ssa
 304     | TODO_update_ssa
 305     | TODO_verify_stmts                 /* todo_flags_finish */
 306  }
 307 };
 308
 309
 310 /* Increase alignment of global arrays to improve vectorization potential.
 311    TODO:
 312    - Consider also structs that have an array field.
 313    - Use ipa analysis to prune arrays that can't be vectorized?
 314      This should involve global alignment analysis and in the future also
 315      array padding.  */
 316
 317 static unsigned int
 318 increase_alignment (void)
 319 {
 320   struct varpool_node *vnode;
 321
 322   /* Increase the alignment of all global arrays for vectorization.  */
 323   for (vnode = varpool_nodes_queue;
 324        vnode;
 325        vnode = vnode->next_needed)
 326     {
 327       tree vectype, decl = vnode->symbol.decl;
 328       tree t;
 329       unsigned int alignment;
 330
 331       t = TREE_TYPE(decl);
 332       if (TREE_CODE (t) != ARRAY_TYPE)
 333         continue;
 334       vectype = get_vectype_for_scalar_type (strip_array_types (t));
 335       if (!vectype)
 336         continue;
 337       alignment = TYPE_ALIGN (vectype);
 338       if (DECL_ALIGN (decl) >= alignment)
 339         continue;
 340
 341       if (vect_can_force_dr_alignment_p (decl, alignment))
 342         {
 343           DECL_ALIGN (decl) = TYPE_ALIGN (vectype);
 344           DECL_USER_ALIGN (decl) = 1;
 345           if (dump_file)
 346             {
 347               fprintf (dump_file, "Increasing alignment of decl: ");
 348               print_generic_expr (dump_file, decl, TDF_SLIM);
 349               fprintf (dump_file, "\n");
 350             }
 351         }
 352     }
 353   return 0;
 354 }
 355
 356
 357 static bool
 358 gate_increase_alignment (void)
 359 {
 360   return flag_section_anchors && flag_tree_vectorize;
 361 }
 362
 363
 364 struct simple_ipa_opt_pass pass_ipa_increase_alignment =
 365 {
 366  {
 367   SIMPLE_IPA_PASS,
 368   "increase_alignment",                 /* name */
 369   gate_increase_alignment,              /* gate */
 370   increase_alignment,                   /* execute */
 371   NULL,                                 /* sub */
 372   NULL,                                 /* next */
 373   0,                                    /* static_pass_number */
 374   TV_IPA_OPT,                           /* tv_id */
 375   0,                                    /* properties_required */
 376   0,                                    /* properties_provided */
 377   0,                                    /* properties_destroyed */
 378   0,                                    /* todo_flags_start */
 379   0                                     /* todo_flags_finish */
 380  }
 381 };