gcc/tree-vect-patterns.c

   1 /* Analysis Utilities for Loop Vectorization.
   2    Copyright (C) 2006, 2007 Free Software Foundation, Inc.
   3    Contributed by Dorit Nuzman <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 #include "config.h"
  22 #include "system.h"
  23 #include "coretypes.h"
  24 #include "tm.h"
  25 #include "ggc.h"
  26 #include "tree.h"
  27
  28 #include "target.h"
  29 #include "basic-block.h"
  30 #include "diagnostic.h"
  31 #include "tree-flow.h"
  32 #include "tree-dump.h"
  33 #include "timevar.h"
  34 #include "cfgloop.h"
  35 #include "expr.h"
  36 #include "optabs.h"
  37 #include "params.h"
  38 #include "tree-data-ref.h"
  39 #include "tree-vectorizer.h"
  40 #include "recog.h"
  41 #include "toplev.h"
  42
  43 /* Function prototypes */
  44 static void vect_pattern_recog_1
  45   (tree (* ) (tree, tree *, tree *), block_stmt_iterator);
  46 static bool widened_name_p (tree, tree, tree *, tree *);
  47
  48 /* Pattern recognition functions  */
  49 static tree vect_recog_widen_sum_pattern (tree, tree *, tree *);
  50 static tree vect_recog_widen_mult_pattern (tree, tree *, tree *);
  51 static tree vect_recog_dot_prod_pattern (tree, tree *, tree *);
  52 static tree vect_recog_pow_pattern (tree, tree *, tree *);
  53 static vect_recog_func_ptr vect_vect_recog_func_ptrs[NUM_PATTERNS] = {
  54         vect_recog_widen_mult_pattern,
  55         vect_recog_widen_sum_pattern,
  56         vect_recog_dot_prod_pattern,
  57         vect_recog_pow_pattern};
  58
  59
  60 /* Function widened_name_p
  61
  62    Check whether NAME, an ssa-name used in USE_STMT,
  63    is a result of a type-promotion, such that:
  64      DEF_STMT: NAME = NOP (name0)
  65    where the type of name0 (HALF_TYPE) is smaller than the type of NAME.
  66 */
  67
  68 static bool
  69 widened_name_p (tree name, tree use_stmt, tree *half_type, tree *def_stmt)
  70 {
  71   tree dummy;
  72   loop_vec_info loop_vinfo;
  73   stmt_vec_info stmt_vinfo;
  74   tree expr;
  75   tree type = TREE_TYPE (name);
  76   tree oprnd0;
  77   enum vect_def_type dt;
  78   tree def;
  79
  80   stmt_vinfo = vinfo_for_stmt (use_stmt);
  81   loop_vinfo = STMT_VINFO_LOOP_VINFO (stmt_vinfo);
  82
  83   if (!vect_is_simple_use (name, loop_vinfo, def_stmt, &def, &dt))
  84     return false;
  85
  86   if (dt != vect_loop_def
  87       && dt != vect_invariant_def && dt != vect_constant_def)
  88     return false;
  89
  90   if (! *def_stmt)
  91     return false;
  92
  93   if (TREE_CODE (*def_stmt) != GIMPLE_MODIFY_STMT)
  94     return false;
  95
  96   expr = GIMPLE_STMT_OPERAND (*def_stmt, 1);
  97   if (TREE_CODE (expr) != NOP_EXPR)
  98     return false;
  99
 100   oprnd0 = TREE_OPERAND (expr, 0);
 101
 102   *half_type = TREE_TYPE (oprnd0);
 103   if (!INTEGRAL_TYPE_P (type) || !INTEGRAL_TYPE_P (*half_type)
 104       || (TYPE_UNSIGNED (type) != TYPE_UNSIGNED (*half_type))
 105       || (TYPE_PRECISION (type) < (TYPE_PRECISION (*half_type) * 2)))
 106     return false;
 107
 108   if (!vect_is_simple_use (oprnd0, loop_vinfo, &dummy, &dummy, &dt))
 109     return false;
 110
 111   return true;
 112 }
 113
 114
 115 /* Function vect_recog_dot_prod_pattern
 116
 117    Try to find the following pattern:
 118
 119      type x_t, y_t;
 120      TYPE1 prod;
 121      TYPE2 sum = init;
 122    loop:
 123      sum_0 = phi <init, sum_1>
 124      S1  x_t = ...
 125      S2  y_t = ...
 126      S3  x_T = (TYPE1) x_t;
 127      S4  y_T = (TYPE1) y_t;
 128      S5  prod = x_T * y_T;
 129      [S6  prod = (TYPE2) prod;  #optional]
 130      S7  sum_1 = prod + sum_0;
 131
 132    where 'TYPE1' is exactly double the size of type 'type', and 'TYPE2' is the
 133    same size of 'TYPE1' or bigger. This is a special case of a reduction
 134    computation.
 135
 136    Input:
 137
 138    * LAST_STMT: A stmt from which the pattern search begins. In the example,
 139    when this function is called with S7, the pattern {S3,S4,S5,S6,S7} will be
 140    detected.
 141
 142    Output:
 143
 144    * TYPE_IN: The type of the input arguments to the pattern.
 145
 146    * TYPE_OUT: The type of the output  of this pattern.
 147
 148    * Return value: A new stmt that will be used to replace the sequence of
 149    stmts that constitute the pattern. In this case it will be:
 150         WIDEN_DOT_PRODUCT <x_t, y_t, sum_0>
 151 */
 152
 153 static tree
 154 vect_recog_dot_prod_pattern (tree last_stmt, tree *type_in, tree *type_out)
 155 {
 156   tree stmt, expr;
 157   tree oprnd0, oprnd1;
 158   tree oprnd00, oprnd01;
 159   stmt_vec_info stmt_vinfo = vinfo_for_stmt (last_stmt);
 160   tree type, half_type;
 161   tree pattern_expr;
 162   tree prod_type;
 163
 164   if (TREE_CODE (last_stmt) != GIMPLE_MODIFY_STMT)
 165     return NULL;
 166
 167   expr = GIMPLE_STMT_OPERAND (last_stmt, 1);
 168   type = TREE_TYPE (expr);
 169
 170   /* Look for the following pattern
 171           DX = (TYPE1) X;
 172           DY = (TYPE1) Y;
 173           DPROD = DX * DY;
 174           DDPROD = (TYPE2) DPROD;
 175           sum_1 = DDPROD + sum_0;
 176      In which
 177      - DX is double the size of X
 178      - DY is double the size of Y
 179      - DX, DY, DPROD all have the same type
 180      - sum is the same size of DPROD or bigger
 181      - sum has been recognized as a reduction variable.
 182
 183      This is equivalent to:
 184        DPROD = X w* Y;          #widen mult
 185        sum_1 = DPROD w+ sum_0;  #widen summation
 186      or
 187        DPROD = X w* Y;          #widen mult
 188        sum_1 = DPROD + sum_0;   #summation
 189    */
 190
 191   /* Starting from LAST_STMT, follow the defs of its uses in search
 192      of the above pattern.  */
 193
 194   if (TREE_CODE (expr) != PLUS_EXPR)
 195     return NULL;
 196
 197   if (STMT_VINFO_IN_PATTERN_P (stmt_vinfo))
 198     {
 199       /* Has been detected as widening-summation?  */
 200
 201       stmt = STMT_VINFO_RELATED_STMT (stmt_vinfo);
 202       expr = GIMPLE_STMT_OPERAND (stmt, 1);
 203       type = TREE_TYPE (expr);
 204       if (TREE_CODE (expr) != WIDEN_SUM_EXPR)
 205         return NULL;
 206       oprnd0 = TREE_OPERAND (expr, 0);
 207       oprnd1 = TREE_OPERAND (expr, 1);
 208       half_type = TREE_TYPE (oprnd0);
 209     }
 210   else
 211     {
 212       tree def_stmt;
 213
 214       if (STMT_VINFO_DEF_TYPE (stmt_vinfo) != vect_reduction_def)
 215         return NULL;
 216       oprnd0 = TREE_OPERAND (expr, 0);
 217       oprnd1 = TREE_OPERAND (expr, 1);
 218       if (TYPE_MAIN_VARIANT (TREE_TYPE (oprnd0)) != TYPE_MAIN_VARIANT (type)
 219           || TYPE_MAIN_VARIANT (TREE_TYPE (oprnd1)) != TYPE_MAIN_VARIANT (type))
 220         return NULL;
 221       stmt = last_stmt;
 222
 223       if (widened_name_p (oprnd0, stmt, &half_type, &def_stmt))
 224         {
 225           stmt = def_stmt;
 226           expr = GIMPLE_STMT_OPERAND (stmt, 1);
 227           oprnd0 = TREE_OPERAND (expr, 0);
 228         }
 229       else
 230         half_type = type;
 231     }
 232
 233   /* So far so good. Since last_stmt was detected as a (summation) reduction,
 234      we know that oprnd1 is the reduction variable (defined by a loop-header
 235      phi), and oprnd0 is an ssa-name defined by a stmt in the loop body.
 236      Left to check that oprnd0 is defined by a (widen_)mult_expr  */
 237
 238   prod_type = half_type;
 239   stmt = SSA_NAME_DEF_STMT (oprnd0);
 240   gcc_assert (stmt);
 241   stmt_vinfo = vinfo_for_stmt (stmt);
 242   gcc_assert (stmt_vinfo);
 243   if (STMT_VINFO_DEF_TYPE (stmt_vinfo) != vect_loop_def)
 244     return NULL;
 245   expr = GIMPLE_STMT_OPERAND (stmt, 1);
 246   if (TREE_CODE (expr) != MULT_EXPR)
 247     return NULL;
 248   if (STMT_VINFO_IN_PATTERN_P (stmt_vinfo))
 249     {
 250       /* Has been detected as a widening multiplication?  */
 251
 252       stmt = STMT_VINFO_RELATED_STMT (stmt_vinfo);
 253       expr = GIMPLE_STMT_OPERAND (stmt, 1);
 254       if (TREE_CODE (expr) != WIDEN_MULT_EXPR)
 255         return NULL;
 256       stmt_vinfo = vinfo_for_stmt (stmt);
 257       gcc_assert (stmt_vinfo);
 258       gcc_assert (STMT_VINFO_DEF_TYPE (stmt_vinfo) == vect_loop_def);
 259       oprnd00 = TREE_OPERAND (expr, 0);
 260       oprnd01 = TREE_OPERAND (expr, 1);
 261     }
 262   else
 263     {
 264       tree half_type0, half_type1;
 265       tree def_stmt;
 266       tree oprnd0, oprnd1;
 267
 268       oprnd0 = TREE_OPERAND (expr, 0);
 269       oprnd1 = TREE_OPERAND (expr, 1);
 270       if (TYPE_MAIN_VARIANT (TREE_TYPE (oprnd0))
 271                                 != TYPE_MAIN_VARIANT (prod_type)
 272           || TYPE_MAIN_VARIANT (TREE_TYPE (oprnd1))
 273                                 != TYPE_MAIN_VARIANT (prod_type))
 274         return NULL;
 275       if (!widened_name_p (oprnd0, stmt, &half_type0, &def_stmt))
 276         return NULL;
 277       oprnd00 = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 0);
 278       if (!widened_name_p (oprnd1, stmt, &half_type1, &def_stmt))
 279         return NULL;
 280       oprnd01 = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt, 1), 0);
 281       if (TYPE_MAIN_VARIANT (half_type0) != TYPE_MAIN_VARIANT (half_type1))
 282         return NULL;
 283       if (TYPE_PRECISION (prod_type) != TYPE_PRECISION (half_type0) * 2)
 284         return NULL;
 285     }
 286
 287   half_type = TREE_TYPE (oprnd00);
 288   *type_in = half_type;
 289   *type_out = type;
 290
 291   /* Pattern detected. Create a stmt to be used to replace the pattern: */
 292   pattern_expr = build3 (DOT_PROD_EXPR, type, oprnd00, oprnd01, oprnd1);
 293   if (vect_print_dump_info (REPORT_DETAILS))
 294     {
 295       fprintf (vect_dump, "vect_recog_dot_prod_pattern: detected: ");
 296       print_generic_expr (vect_dump, pattern_expr, TDF_SLIM);
 297     }
 298   return pattern_expr;
 299 }
 300
 301
 302 /* Function vect_recog_widen_mult_pattern
 303
 304    Try to find the following pattern:
 305
 306      type a_t, b_t;
 307      TYPE a_T, b_T, prod_T;
 308
 309      S1  a_t = ;
 310      S2  b_t = ;
 311      S3  a_T = (TYPE) a_t;
 312      S4  b_T = (TYPE) b_t;
 313      S5  prod_T = a_T * b_T;
 314
 315    where type 'TYPE' is at least double the size of type 'type'.
 316
 317    Input:
 318
 319    * LAST_STMT: A stmt from which the pattern search begins. In the example,
 320    when this function is called with S5, the pattern {S3,S4,S5} is be detected.
 321
 322    Output:
 323
 324    * TYPE_IN: The type of the input arguments to the pattern.
 325
 326    * TYPE_OUT: The type of the output  of this pattern.
 327
 328    * Return value: A new stmt that will be used to replace the sequence of
 329    stmts that constitute the pattern. In this case it will be:
 330         WIDEN_MULT <a_t, b_t>
 331 */
 332
 333 static tree
 334 vect_recog_widen_mult_pattern (tree last_stmt,
 335                                tree *type_in,
 336                                tree *type_out)
 337 {
 338   tree expr;
 339   tree def_stmt0, def_stmt1;
 340   tree oprnd0, oprnd1;
 341   tree type, half_type0, half_type1;
 342   tree pattern_expr;
 343   tree vectype;
 344   tree dummy;
 345   enum tree_code dummy_code;
 346
 347   if (TREE_CODE (last_stmt) != GIMPLE_MODIFY_STMT)
 348     return NULL;
 349
 350   expr = GIMPLE_STMT_OPERAND (last_stmt, 1);
 351   type = TREE_TYPE (expr);
 352
 353   /* Starting from LAST_STMT, follow the defs of its uses in search
 354      of the above pattern.  */
 355
 356   if (TREE_CODE (expr) != MULT_EXPR)
 357     return NULL;
 358
 359   oprnd0 = TREE_OPERAND (expr, 0);
 360   oprnd1 = TREE_OPERAND (expr, 1);
 361   if (TYPE_MAIN_VARIANT (TREE_TYPE (oprnd0)) != TYPE_MAIN_VARIANT (type)
 362       || TYPE_MAIN_VARIANT (TREE_TYPE (oprnd1)) != TYPE_MAIN_VARIANT (type))
 363     return NULL;
 364
 365   /* Check argument 0 */
 366   if (!widened_name_p (oprnd0, last_stmt, &half_type0, &def_stmt0))
 367     return NULL;
 368   oprnd0 = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt0, 1), 0);
 369
 370   /* Check argument 1 */
 371   if (!widened_name_p (oprnd1, last_stmt, &half_type1, &def_stmt1))
 372     return NULL;
 373   oprnd1 = TREE_OPERAND (GIMPLE_STMT_OPERAND (def_stmt1, 1), 0);
 374
 375   if (TYPE_MAIN_VARIANT (half_type0) != TYPE_MAIN_VARIANT (half_type1))
 376     return NULL;
 377
 378   /* Pattern detected.  */
 379   if (vect_print_dump_info (REPORT_DETAILS))
 380     fprintf (vect_dump, "vect_recog_widen_mult_pattern: detected: ");
 381
 382   /* Check target support  */
 383   vectype = get_vectype_for_scalar_type (half_type0);
 384   if (!vectype
 385       || !supportable_widening_operation (WIDEN_MULT_EXPR, last_stmt, vectype,
 386                                        &dummy, &dummy, &dummy_code,
 387                                        &dummy_code))
 388     return NULL;
 389
 390   *type_in = vectype;
 391   *type_out = NULL_TREE;
 392
 393   /* Pattern supported. Create a stmt to be used to replace the pattern: */
 394   pattern_expr = build2 (WIDEN_MULT_EXPR, type, oprnd0, oprnd1);
 395   if (vect_print_dump_info (REPORT_DETAILS))
 396     print_generic_expr (vect_dump, pattern_expr, TDF_SLIM);
 397   return pattern_expr;
 398 }
 399
 400
 401 /* Function vect_recog_pow_pattern
 402
 403    Try to find the following pattern:
 404
 405      x = POW (y, N);
 406
 407    with POW being one of pow, powf, powi, powif and N being
 408    either 2 or 0.5.
 409
 410    Input:
 411
 412    * LAST_STMT: A stmt from which the pattern search begins.
 413
 414    Output:
 415
 416    * TYPE_IN: The type of the input arguments to the pattern.
 417
 418    * TYPE_OUT: The type of the output of this pattern.
 419
 420    * Return value: A new stmt that will be used to replace the sequence of
 421    stmts that constitute the pattern. In this case it will be:
 422         x * x
 423    or
 424         sqrt (x)
 425 */
 426
 427 static tree
 428 vect_recog_pow_pattern (tree last_stmt, tree *type_in, tree *type_out)
 429 {
 430   tree expr;
 431   tree type;
 432   tree fn, base, exp;
 433
 434   if (TREE_CODE (last_stmt) != GIMPLE_MODIFY_STMT)
 435     return NULL;
 436
 437   expr = GIMPLE_STMT_OPERAND (last_stmt, 1);
 438   type = TREE_TYPE (expr);
 439
 440   if (TREE_CODE (expr) != CALL_EXPR)
 441     return NULL_TREE;
 442
 443   fn = get_callee_fndecl (expr);
 444   switch (DECL_FUNCTION_CODE (fn))
 445     {
 446     case BUILT_IN_POWIF:
 447     case BUILT_IN_POWI:
 448     case BUILT_IN_POWF:
 449     case BUILT_IN_POW:
 450       base = CALL_EXPR_ARG (expr, 0);
 451       exp = CALL_EXPR_ARG (expr, 1);
 452       if (TREE_CODE (exp) != REAL_CST
 453           && TREE_CODE (exp) != INTEGER_CST)
 454         return NULL_TREE;
 455       break;
 456
 457     default:;
 458       return NULL_TREE;
 459     }
 460
 461   /* We now have a pow or powi builtin function call with a constant
 462      exponent.  */
 463
 464   *type_out = NULL_TREE;
 465
 466   /* Catch squaring.  */
 467   if ((host_integerp (exp, 0)
 468        && tree_low_cst (exp, 0) == 2)
 469       || (TREE_CODE (exp) == REAL_CST
 470           && REAL_VALUES_EQUAL (TREE_REAL_CST (exp), dconst2)))
 471     {
 472       *type_in = TREE_TYPE (base);
 473       return build2 (MULT_EXPR, TREE_TYPE (base), base, base);
 474     }
 475
 476   /* Catch square root.  */
 477   if (TREE_CODE (exp) == REAL_CST
 478       && REAL_VALUES_EQUAL (TREE_REAL_CST (exp), dconsthalf))
 479     {
 480       tree newfn = mathfn_built_in (TREE_TYPE (base), BUILT_IN_SQRT);
 481       *type_in = get_vectype_for_scalar_type (TREE_TYPE (base));
 482       if (*type_in)
 483         {
 484           newfn = build_call_expr (newfn, 1, base);
 485           if (vectorizable_function (newfn, *type_in, *type_in) != NULL_TREE)
 486             return newfn;
 487         }
 488     }
 489
 490   return NULL_TREE;
 491 }
 492
 493
 494 /* Function vect_recog_widen_sum_pattern
 495
 496    Try to find the following pattern:
 497
 498      type x_t;
 499      TYPE x_T, sum = init;
 500    loop:
 501      sum_0 = phi <init, sum_1>
 502      S1  x_t = *p;
 503      S2  x_T = (TYPE) x_t;
 504      S3  sum_1 = x_T + sum_0;
 505
 506    where type 'TYPE' is at least double the size of type 'type', i.e - we're
 507    summing elements of type 'type' into an accumulator of type 'TYPE'. This is
 508    a special case of a reduction computation.
 509
 510    Input:
 511
 512    * LAST_STMT: A stmt from which the pattern search begins. In the example,
 513    when this function is called with S3, the pattern {S2,S3} will be detected.
 514
 515    Output:
 516
 517    * TYPE_IN: The type of the input arguments to the pattern.
 518
 519    * TYPE_OUT: The type of the output of this pattern.
 520
 521    * Return value: A new stmt that will be used to replace the sequence of
 522    stmts that constitute the pattern. In this case it will be:
 523         WIDEN_SUM <x_t, sum_0>
 524 */
 525
 526 static tree
 527 vect_recog_widen_sum_pattern (tree last_stmt, tree *type_in, tree *type_out)
 528 {
 529   tree stmt, expr;
 530   tree oprnd0, oprnd1;
 531   stmt_vec_info stmt_vinfo = vinfo_for_stmt (last_stmt);
 532   tree type, half_type;
 533   tree pattern_expr;
 534
 535   if (TREE_CODE (last_stmt) != GIMPLE_MODIFY_STMT)
 536     return NULL;
 537
 538   expr = GIMPLE_STMT_OPERAND (last_stmt, 1);
 539   type = TREE_TYPE (expr);
 540
 541   /* Look for the following pattern
 542           DX = (TYPE) X;
 543           sum_1 = DX + sum_0;
 544      In which DX is at least double the size of X, and sum_1 has been
 545      recognized as a reduction variable.
 546    */
 547
 548   /* Starting from LAST_STMT, follow the defs of its uses in search
 549      of the above pattern.  */
 550
 551   if (TREE_CODE (expr) != PLUS_EXPR)
 552     return NULL;
 553
 554   if (STMT_VINFO_DEF_TYPE (stmt_vinfo) != vect_reduction_def)
 555     return NULL;
 556
 557   oprnd0 = TREE_OPERAND (expr, 0);
 558   oprnd1 = TREE_OPERAND (expr, 1);
 559   if (TYPE_MAIN_VARIANT (TREE_TYPE (oprnd0)) != TYPE_MAIN_VARIANT (type)
 560       || TYPE_MAIN_VARIANT (TREE_TYPE (oprnd1)) != TYPE_MAIN_VARIANT (type))
 561     return NULL;
 562
 563   /* So far so good. Since last_stmt was detected as a (summation) reduction,
 564      we know that oprnd1 is the reduction variable (defined by a loop-header
 565      phi), and oprnd0 is an ssa-name defined by a stmt in the loop body.
 566      Left to check that oprnd0 is defined by a cast from type 'type' to type
 567      'TYPE'.  */
 568
 569   if (!widened_name_p (oprnd0, last_stmt, &half_type, &stmt))
 570     return NULL;
 571
 572   oprnd0 = TREE_OPERAND (GIMPLE_STMT_OPERAND (stmt, 1), 0);
 573   *type_in = half_type;
 574   *type_out = type;
 575
 576   /* Pattern detected. Create a stmt to be used to replace the pattern: */
 577   pattern_expr = build2 (WIDEN_SUM_EXPR, type, oprnd0, oprnd1);
 578   if (vect_print_dump_info (REPORT_DETAILS))
 579     {
 580       fprintf (vect_dump, "vect_recog_widen_sum_pattern: detected: ");
 581       print_generic_expr (vect_dump, pattern_expr, TDF_SLIM);
 582     }
 583   return pattern_expr;
 584 }
 585
 586
 587 /* Function vect_pattern_recog_1
 588
 589    Input:
 590    PATTERN_RECOG_FUNC: A pointer to a function that detects a certain
 591         computation pattern.
 592    STMT: A stmt from which the pattern search should start.
 593
 594    If PATTERN_RECOG_FUNC successfully detected the pattern, it creates an
 595    expression that computes the same functionality and can be used to
 596    replace the sequence of stmts that are involved in the pattern.
 597
 598    Output:
 599    This function checks if the expression returned by PATTERN_RECOG_FUNC is
 600    supported in vector form by the target.  We use 'TYPE_IN' to obtain the
 601    relevant vector type. If 'TYPE_IN' is already a vector type, then this
 602    indicates that target support had already been checked by PATTERN_RECOG_FUNC.
 603    If 'TYPE_OUT' is also returned by PATTERN_RECOG_FUNC, we check that it fits
 604    to the available target pattern.
 605
 606    This function also does some bookkeeping, as explained in the documentation
 607    for vect_recog_pattern.  */
 608
 609 static void
 610 vect_pattern_recog_1 (
 611         tree (* vect_recog_func) (tree, tree *, tree *),
 612         block_stmt_iterator si)
 613 {
 614   tree stmt = bsi_stmt (si);
 615   stmt_vec_info stmt_info = vinfo_for_stmt (stmt);
 616   stmt_vec_info pattern_stmt_info;
 617   loop_vec_info loop_vinfo = STMT_VINFO_LOOP_VINFO (stmt_info);
 618   tree pattern_expr;
 619   tree pattern_vectype;
 620   tree type_in, type_out;
 621   tree pattern_type;
 622   enum tree_code code;
 623   tree var, var_name;
 624   stmt_ann_t ann;
 625
 626   pattern_expr = (* vect_recog_func) (stmt, &type_in, &type_out);
 627   if (!pattern_expr)
 628     return;
 629
 630   if (VECTOR_MODE_P (TYPE_MODE (type_in)))
 631     {
 632       /* No need to check target support (already checked by the pattern
 633          recognition function).  */
 634       pattern_vectype = type_in;
 635     }
 636   else
 637     {
 638       enum tree_code vec_mode;
 639       enum insn_code icode;
 640       optab optab;
 641
 642       /* Check target support  */
 643       pattern_vectype = get_vectype_for_scalar_type (type_in);
 644       if (!pattern_vectype)
 645         return;
 646
 647       optab = optab_for_tree_code (TREE_CODE (pattern_expr), pattern_vectype);
 648       vec_mode = TYPE_MODE (pattern_vectype);
 649       if (!optab
 650           || (icode = optab->handlers[(int) vec_mode].insn_code) ==
 651               CODE_FOR_nothing
 652           || (type_out
 653               && (!get_vectype_for_scalar_type (type_out)
 654                   || (insn_data[icode].operand[0].mode !=
 655                       TYPE_MODE (get_vectype_for_scalar_type (type_out))))))
 656         return;
 657     }
 658
 659   /* Found a vectorizable pattern.  */
 660   if (vect_print_dump_info (REPORT_DETAILS))
 661     {
 662       fprintf (vect_dump, "pattern recognized: ");
 663       print_generic_expr (vect_dump, pattern_expr, TDF_SLIM);
 664     }
 665
 666   /* Mark the stmts that are involved in the pattern,
 667      create a new stmt to express the pattern and insert it.  */
 668   code = TREE_CODE (pattern_expr);
 669   pattern_type = TREE_TYPE (pattern_expr);
 670   var = create_tmp_var (pattern_type, "patt");
 671   add_referenced_var (var);
 672   var_name = make_ssa_name (var, NULL_TREE);
 673   pattern_expr = build_gimple_modify_stmt (var_name, pattern_expr);
 674   SSA_NAME_DEF_STMT (var_name) = pattern_expr;
 675   bsi_insert_before (&si, pattern_expr, BSI_SAME_STMT);
 676   ann = stmt_ann (pattern_expr);
 677   set_stmt_info (ann, new_stmt_vec_info (pattern_expr, loop_vinfo));
 678   pattern_stmt_info = vinfo_for_stmt (pattern_expr);
 679
 680   STMT_VINFO_RELATED_STMT (pattern_stmt_info) = stmt;
 681   STMT_VINFO_DEF_TYPE (pattern_stmt_info) = STMT_VINFO_DEF_TYPE (stmt_info);
 682   STMT_VINFO_VECTYPE (pattern_stmt_info) = pattern_vectype;
 683   STMT_VINFO_IN_PATTERN_P (stmt_info) = true;
 684   STMT_VINFO_RELATED_STMT (stmt_info) = pattern_expr;
 685
 686   return;
 687 }
 688
 689
 690 /* Function vect_pattern_recog
 691
 692    Input:
 693    LOOP_VINFO - a struct_loop_info of a loop in which we want to look for
 694         computation idioms.
 695
 696    Output - for each computation idiom that is detected we insert a new stmt
 697         that provides the same functionality and that can be vectorized. We
 698         also record some information in the struct_stmt_info of the relevant
 699         stmts, as explained below:
 700
 701    At the entry to this function we have the following stmts, with the
 702    following initial value in the STMT_VINFO fields:
 703
 704          stmt                     in_pattern_p  related_stmt    vec_stmt
 705          S1: a_i = ....                 -       -               -
 706          S2: a_2 = ..use(a_i)..         -       -               -
 707          S3: a_1 = ..use(a_2)..         -       -               -
 708          S4: a_0 = ..use(a_1)..         -       -               -
 709          S5: ... = ..use(a_0)..         -       -               -
 710
 711    Say the sequence {S1,S2,S3,S4} was detected as a pattern that can be
 712    represented by a single stmt. We then:
 713    - create a new stmt S6 that will replace the pattern.
 714    - insert the new stmt S6 before the last stmt in the pattern
 715    - fill in the STMT_VINFO fields as follows:
 716
 717                                   in_pattern_p  related_stmt    vec_stmt
 718          S1: a_i = ....                 -       -               -
 719          S2: a_2 = ..use(a_i)..         -       -               -
 720          S3: a_1 = ..use(a_2)..         -       -               -
 721        > S6: a_new = ....               -       S4              -
 722          S4: a_0 = ..use(a_1)..         true    S6              -
 723          S5: ... = ..use(a_0)..         -       -               -
 724
 725    (the last stmt in the pattern (S4) and the new pattern stmt (S6) point
 726     to each other through the RELATED_STMT field).
 727
 728    S6 will be marked as relevant in vect_mark_stmts_to_be_vectorized instead
 729    of S4 because it will replace all its uses.  Stmts {S1,S2,S3} will
 730    remain irrelevant unless used by stmts other than S4.
 731
 732    If vectorization succeeds, vect_transform_stmt will skip over {S1,S2,S3}
 733    (because they are marked as irrelevant). It will vectorize S6, and record
 734    a pointer to the new vector stmt VS6 both from S6 (as usual), and also
 735    from S4. We do that so that when we get to vectorizing stmts that use the
 736    def of S4 (like S5 that uses a_0), we'll know where to take the relevant
 737    vector-def from. S4 will be skipped, and S5 will be vectorized as usual:
 738
 739                                   in_pattern_p  related_stmt    vec_stmt
 740          S1: a_i = ....                 -       -               -
 741          S2: a_2 = ..use(a_i)..         -       -               -
 742          S3: a_1 = ..use(a_2)..         -       -               -
 743        > VS6: va_new = ....             -       -               -
 744          S6: a_new = ....               -       S4              VS6
 745          S4: a_0 = ..use(a_1)..         true    S6              VS6
 746        > VS5: ... = ..vuse(va_new)..    -       -               -
 747          S5: ... = ..use(a_0)..         -       -               -
 748
 749    DCE could then get rid of {S1,S2,S3,S4,S5,S6} (if their defs are not used
 750    elsewhere), and we'll end up with:
 751
 752         VS6: va_new = ....
 753         VS5: ... = ..vuse(va_new)..
 754
 755    If vectorization does not succeed, DCE will clean S6 away (its def is
 756    not used), and we'll end up with the original sequence.
 757 */
 758
 759 void
 760 vect_pattern_recog (loop_vec_info loop_vinfo)
 761 {
 762   struct loop *loop = LOOP_VINFO_LOOP (loop_vinfo);
 763   basic_block *bbs = LOOP_VINFO_BBS (loop_vinfo);
 764   unsigned int nbbs = loop->num_nodes;
 765   block_stmt_iterator si;
 766   tree stmt;
 767   unsigned int i, j;
 768   tree (* vect_recog_func_ptr) (tree, tree *, tree *);
 769
 770   if (vect_print_dump_info (REPORT_DETAILS))
 771     fprintf (vect_dump, "=== vect_pattern_recog ===");
 772
 773   /* Scan through the loop stmts, applying the pattern recognition
 774      functions starting at each stmt visited:  */
 775   for (i = 0; i < nbbs; i++)
 776     {
 777       basic_block bb = bbs[i];
 778       for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
 779         {
 780           stmt = bsi_stmt (si);
 781
 782           /* Scan over all generic vect_recog_xxx_pattern functions.  */
 783           for (j = 0; j < NUM_PATTERNS; j++)
 784             {
 785               vect_recog_func_ptr = vect_vect_recog_func_ptrs[j];
 786               vect_pattern_recog_1 (vect_recog_func_ptr, si);
 787             }
 788         }
 789     }
 790 }