gcc/gimple-isel.cc

   1 /* Schedule GIMPLE vector statements.
   2    Copyright (C) 2020-2023 Free Software Foundation, Inc.
   3
   4 This file is part of GCC.
   5
   6 GCC is free software; you can redistribute it and/or modify it
   7 under the terms of the GNU General Public License as published by the
   8 Free Software Foundation; either version 3, or (at your option) any
   9 later version.
  10
  11 GCC is distributed in the hope that it will be useful, but WITHOUT
  12 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14 for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GCC; see the file COPYING3.  If not see
  18 <http://www.gnu.org/licenses/>.  */
  19
  20 #include "config.h"
  21 #include "system.h"
  22 #include "coretypes.h"
  23 #include "backend.h"
  24 #include "rtl.h"
  25 #include "tree.h"
  26 #include "gimple.h"
  27 #include "tree-pass.h"
  28 #include "ssa.h"
  29 #include "expmed.h"
  30 #include "optabs-tree.h"
  31 #include "tree-eh.h"
  32 #include "gimple-iterator.h"
  33 #include "gimplify-me.h"
  34 #include "gimplify.h"
  35 #include "tree-cfg.h"
  36 #include "bitmap.h"
  37 #include "tree-ssa-dce.h"
  38 #include "memmodel.h"
  39 #include "optabs.h"
  40 #include "gimple-fold.h"
  41 #include "internal-fn.h"
  42
  43 /* Expand all ARRAY_REF(VIEW_CONVERT_EXPR) gimple assignments into calls to
  44    internal function based on vector type of selected expansion.
  45
  46    For vec_set:
  47
  48      VIEW_CONVERT_EXPR<int[4]>(u)[_1] = i_4(D);
  49    =>
  50      _7 = u;
  51      _8 = .VEC_SET (_7, i_4(D), _1);
  52      u = _8;
  53
  54    For vec_extract:
  55
  56       _3 = VIEW_CONVERT_EXPR<intD.1[4]>(vD.2208)[idx_2(D)];
  57    =>
  58       _4 = vD.2208;
  59       _3 = .VEC_EXTRACT (_4, idx_2(D));  */
  60
  61 static bool
  62 gimple_expand_vec_set_extract_expr (struct function *fun,
  63                                     gimple_stmt_iterator *gsi)
  64 {
  65   gcall *new_stmt = NULL;
  66   gassign *ass_stmt = NULL;
  67   bool cfg_changed = false;
  68
  69   /* Only consider code == GIMPLE_ASSIGN.  */
  70   gassign *stmt = dyn_cast<gassign *> (gsi_stmt (*gsi));
  71   if (!stmt)
  72     return false;
  73
  74   bool is_extract = false;
  75
  76   tree lhs = gimple_assign_lhs (stmt);
  77   tree rhs = gimple_assign_rhs1 (stmt);
  78   tree val, ref;
  79   if (TREE_CODE (lhs) == ARRAY_REF)
  80     {
  81       /* Assume it is a vec_set.  */
  82       val = rhs;
  83       ref = lhs;
  84     }
  85   else if (TREE_CODE (rhs) == ARRAY_REF)
  86     {
  87       /* vec_extract.  */
  88       is_extract = true;
  89       val = lhs;
  90       ref = rhs;
  91     }
  92   else
  93     return false;
  94
  95   tree op0 = TREE_OPERAND (ref, 0);
  96   if (TREE_CODE (op0) == VIEW_CONVERT_EXPR && DECL_P (TREE_OPERAND (op0, 0))
  97       && VECTOR_TYPE_P (TREE_TYPE (TREE_OPERAND (op0, 0)))
  98       && TYPE_MODE (TREE_TYPE (ref))
  99            == TYPE_MODE (TREE_TYPE (TREE_TYPE (TREE_OPERAND (op0, 0)))))
 100     {
 101       tree pos = TREE_OPERAND (ref, 1);
 102
 103       tree view_op0 = TREE_OPERAND (op0, 0);
 104       machine_mode outermode = TYPE_MODE (TREE_TYPE (view_op0));
 105       machine_mode extract_mode = TYPE_MODE (TREE_TYPE (ref));
 106
 107       if (auto_var_in_fn_p (view_op0, fun->decl)
 108           && !TREE_ADDRESSABLE (view_op0)
 109           && ((!is_extract && can_vec_set_var_idx_p (outermode))
 110               || (is_extract
 111                   && can_vec_extract_var_idx_p (outermode, extract_mode))))
 112         {
 113           location_t loc = gimple_location (stmt);
 114           tree var_src = make_ssa_name (TREE_TYPE (view_op0));
 115
 116           ass_stmt = gimple_build_assign (var_src, view_op0);
 117           gimple_set_vuse (ass_stmt, gimple_vuse (stmt));
 118           gimple_set_location (ass_stmt, loc);
 119           gsi_insert_before (gsi, ass_stmt, GSI_SAME_STMT);
 120
 121           if (!is_extract)
 122             {
 123               tree var_dst = make_ssa_name (TREE_TYPE (view_op0));
 124
 125               new_stmt = gimple_build_call_internal (IFN_VEC_SET, 3, var_src,
 126                                                      val, pos);
 127
 128               gimple_call_set_lhs (new_stmt, var_dst);
 129               gimple_set_location (new_stmt, loc);
 130               gsi_insert_before (gsi, new_stmt, GSI_SAME_STMT);
 131
 132               ass_stmt = gimple_build_assign (view_op0, var_dst);
 133               gimple_set_location (ass_stmt, loc);
 134               gimple_move_vops (ass_stmt, stmt);
 135               gsi_insert_before (gsi, ass_stmt, GSI_SAME_STMT);
 136
 137               basic_block bb = gimple_bb (stmt);
 138               if (gsi_remove (gsi, true)
 139                   && gimple_purge_dead_eh_edges (bb))
 140                 cfg_changed = true;
 141               *gsi = gsi_for_stmt (ass_stmt);
 142             }
 143           else
 144             {
 145               new_stmt
 146                 = gimple_build_call_internal (IFN_VEC_EXTRACT, 2, var_src, pos);
 147               gimple_call_set_lhs (new_stmt, lhs);
 148
 149               gsi_replace (gsi, new_stmt, true);
 150               cfg_changed = true;
 151             }
 152         }
 153     }
 154
 155   return cfg_changed;
 156 }
 157
 158 /* Expand all VEC_COND_EXPR gimple assignments into calls to internal
 159    function based on type of selected expansion.  */
 160
 161 static gimple *
 162 gimple_expand_vec_cond_expr (struct function *fun, gimple_stmt_iterator *gsi,
 163                              hash_map<tree, unsigned int> *vec_cond_ssa_name_uses)
 164 {
 165   tree lhs, op0a = NULL_TREE, op0b = NULL_TREE;
 166   enum tree_code code;
 167   enum tree_code tcode;
 168   machine_mode cmp_op_mode;
 169   bool unsignedp;
 170   enum insn_code icode;
 171   imm_use_iterator imm_iter;
 172
 173   /* Only consider code == GIMPLE_ASSIGN.  */
 174   gassign *stmt = dyn_cast<gassign *> (gsi_stmt (*gsi));
 175   if (!stmt)
 176     return NULL;
 177
 178   code = gimple_assign_rhs_code (stmt);
 179   if (code != VEC_COND_EXPR)
 180     return NULL;
 181
 182   tree op0 = gimple_assign_rhs1 (stmt);
 183   tree op1 = gimple_assign_rhs2 (stmt);
 184   tree op2 = gimple_assign_rhs3 (stmt);
 185   lhs = gimple_assign_lhs (stmt);
 186   machine_mode mode = TYPE_MODE (TREE_TYPE (lhs));
 187
 188   /* Lower mask typed, non-vector mode VEC_COND_EXPRs to bitwise operations.
 189      Those can end up generated by folding and at least for integer mode masks
 190      we cannot expect vcond expanders to exist.  We lower a ? b : c
 191      to (b & a) | (c & ~a).  */
 192   if (VECTOR_BOOLEAN_TYPE_P (TREE_TYPE (lhs))
 193       && !VECTOR_MODE_P (mode))
 194     {
 195       gcc_assert (types_compatible_p (TREE_TYPE (op0), TREE_TYPE (op1)));
 196       gimple_seq stmts = NULL;
 197       tree type = TREE_TYPE (lhs);
 198       location_t loc = gimple_location (stmt);
 199       tree tem0 = gimple_build (&stmts, loc, BIT_AND_EXPR, type, op1, op0);
 200       tree tem1 = gimple_build (&stmts, loc, BIT_NOT_EXPR, type, op0);
 201       tree tem2 = gimple_build (&stmts, loc, BIT_AND_EXPR, type, op2, tem1);
 202       tree tem3 = gimple_build (&stmts, loc, BIT_IOR_EXPR, type, tem0, tem2);
 203       gsi_insert_seq_before (gsi, stmts, GSI_SAME_STMT);
 204       return gimple_build_assign (lhs, tem3);
 205     }
 206
 207   bool can_compute_op0 = true;
 208   gcc_assert (!COMPARISON_CLASS_P (op0));
 209   if (TREE_CODE (op0) == SSA_NAME)
 210     {
 211       unsigned int used_vec_cond_exprs = 0;
 212       unsigned int *slot = vec_cond_ssa_name_uses->get (op0);
 213       if (slot)
 214         used_vec_cond_exprs = *slot;
 215       else
 216         {
 217           gimple *use_stmt;
 218           FOR_EACH_IMM_USE_STMT (use_stmt, imm_iter, op0)
 219             {
 220               gassign *assign = dyn_cast<gassign *> (use_stmt);
 221               if (assign != NULL
 222                   && gimple_assign_rhs_code (assign) == VEC_COND_EXPR
 223                   && gimple_assign_rhs1 (assign) == op0)
 224                 used_vec_cond_exprs++;
 225             }
 226           vec_cond_ssa_name_uses->put (op0, used_vec_cond_exprs);
 227         }
 228
 229       gassign *def_stmt = dyn_cast<gassign *> (SSA_NAME_DEF_STMT (op0));
 230       if (def_stmt)
 231         {
 232           tcode = gimple_assign_rhs_code (def_stmt);
 233           op0a = gimple_assign_rhs1 (def_stmt);
 234           op0b = gimple_assign_rhs2 (def_stmt);
 235
 236           tree op0_type = TREE_TYPE (op0);
 237           tree op0a_type = TREE_TYPE (op0a);
 238           if (TREE_CODE_CLASS (tcode) == tcc_comparison)
 239             can_compute_op0 = expand_vec_cmp_expr_p (op0a_type, op0_type,
 240                                                      tcode);
 241
 242           /* Try to fold x CMP y ? -1 : 0 to x CMP y.  */
 243           if (can_compute_op0
 244               && integer_minus_onep (op1)
 245               && integer_zerop (op2)
 246               && TYPE_MODE (TREE_TYPE (lhs)) == TYPE_MODE (TREE_TYPE (op0)))
 247             {
 248               tree conv_op = build1 (VIEW_CONVERT_EXPR, TREE_TYPE (lhs), op0);
 249               gassign *new_stmt = gimple_build_assign (lhs, conv_op);
 250               gsi_replace (gsi, new_stmt, true);
 251               return new_stmt;
 252             }
 253
 254           /* When the compare has EH we do not want to forward it when
 255              it has multiple uses and in general because of the complication
 256              with EH redirection.  */
 257           if (stmt_can_throw_internal (fun, def_stmt))
 258             tcode = TREE_CODE (op0);
 259
 260           /* If we can compute op0 and have multiple uses, keep the SSA
 261              name and use vcond_mask.  */
 262           else if (can_compute_op0
 263                    && used_vec_cond_exprs >= 2
 264                    && (get_vcond_mask_icode (mode, TYPE_MODE (op0_type))
 265                        != CODE_FOR_nothing))
 266             tcode = TREE_CODE (op0);
 267         }
 268       else
 269         tcode = TREE_CODE (op0);
 270     }
 271   else
 272     tcode = TREE_CODE (op0);
 273
 274   if (TREE_CODE_CLASS (tcode) != tcc_comparison)
 275     {
 276       gcc_assert (VECTOR_BOOLEAN_TYPE_P (TREE_TYPE (op0)));
 277       if (get_vcond_mask_icode (mode, TYPE_MODE (TREE_TYPE (op0)))
 278           != CODE_FOR_nothing)
 279         return gimple_build_call_internal (IFN_VCOND_MASK, 3, op0, op1, op2);
 280       /* Fake op0 < 0.  */
 281       else
 282         {
 283           gcc_assert (GET_MODE_CLASS (TYPE_MODE (TREE_TYPE (op0)))
 284                       == MODE_VECTOR_INT);
 285           op0a = op0;
 286           op0b = build_zero_cst (TREE_TYPE (op0));
 287           tcode = LT_EXPR;
 288         }
 289     }
 290   cmp_op_mode = TYPE_MODE (TREE_TYPE (op0a));
 291   unsignedp = TYPE_UNSIGNED (TREE_TYPE (op0a));
 292
 293   gcc_assert (known_eq (GET_MODE_NUNITS (mode),
 294                         GET_MODE_NUNITS (cmp_op_mode)));
 295
 296   icode = get_vcond_icode (mode, cmp_op_mode, unsignedp);
 297   /* Some targets do not have vcondeq and only vcond with NE/EQ
 298      but not vcondu, so make sure to also try vcond here as
 299      vcond_icode_p would canonicalize the optab query to.  */
 300   if (icode == CODE_FOR_nothing
 301       && (tcode == NE_EXPR || tcode == EQ_EXPR)
 302       && ((icode = get_vcond_icode (mode, cmp_op_mode, !unsignedp))
 303           != CODE_FOR_nothing))
 304     unsignedp = !unsignedp;
 305   if (icode == CODE_FOR_nothing)
 306     {
 307       if (tcode == LT_EXPR
 308           && op0a == op0)
 309         {
 310           /* A VEC_COND_EXPR condition could be folded from EQ_EXPR/NE_EXPR
 311              into a constant when only get_vcond_eq_icode is supported.
 312              Try changing it to NE_EXPR.  */
 313           tcode = NE_EXPR;
 314         }
 315       if ((tcode == EQ_EXPR || tcode == NE_EXPR)
 316           && direct_internal_fn_supported_p (IFN_VCONDEQ, TREE_TYPE (lhs),
 317                                              TREE_TYPE (op0a),
 318                                              OPTIMIZE_FOR_BOTH))
 319         {
 320           tree tcode_tree = build_int_cst (integer_type_node, tcode);
 321           return gimple_build_call_internal (IFN_VCONDEQ, 5, op0a, op0b, op1,
 322                                              op2, tcode_tree);
 323         }
 324
 325       gcc_assert (VECTOR_BOOLEAN_TYPE_P (TREE_TYPE (op0))
 326                   && can_compute_op0
 327                   && (get_vcond_mask_icode (mode, TYPE_MODE (TREE_TYPE (op0)))
 328                       != CODE_FOR_nothing));
 329       return gimple_build_call_internal (IFN_VCOND_MASK, 3, op0, op1, op2);
 330     }
 331
 332   tree tcode_tree = build_int_cst (integer_type_node, tcode);
 333   return gimple_build_call_internal (unsignedp ? IFN_VCONDU : IFN_VCOND,
 334                                      5, op0a, op0b, op1, op2, tcode_tree);
 335 }
 336
 337
 338
 339 namespace {
 340
 341 const pass_data pass_data_gimple_isel =
 342 {
 343   GIMPLE_PASS, /* type */
 344   "isel", /* name */
 345   OPTGROUP_VEC, /* optinfo_flags */
 346   TV_NONE, /* tv_id */
 347   PROP_cfg, /* properties_required */
 348   0, /* properties_provided */
 349   0, /* properties_destroyed */
 350   0, /* todo_flags_start */
 351   TODO_update_ssa, /* todo_flags_finish */
 352 };
 353
 354 class pass_gimple_isel : public gimple_opt_pass
 355 {
 356 public:
 357   pass_gimple_isel (gcc::context *ctxt)
 358     : gimple_opt_pass (pass_data_gimple_isel, ctxt)
 359   {}
 360
 361   /* opt_pass methods: */
 362   bool gate (function *) final override
 363     {
 364       return true;
 365     }
 366
 367   unsigned int execute (function *fun) final override;
 368 }; // class pass_gimple_isel
 369
 370
 371 /* Iterate all gimple statements and perform pre RTL expansion
 372    GIMPLE massaging to improve instruction selection.  */
 373
 374 unsigned int
 375 pass_gimple_isel::execute (struct function *fun)
 376 {
 377   gimple_stmt_iterator gsi;
 378   basic_block bb;
 379   hash_map<tree, unsigned int> vec_cond_ssa_name_uses;
 380   auto_bitmap dce_ssa_names;
 381   bool cfg_changed = false;
 382
 383   FOR_EACH_BB_FN (bb, fun)
 384     {
 385       for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
 386         {
 387           /* Pre-expand VEC_COND_EXPRs to .VCOND* internal function
 388              calls mapping to supported optabs.  */
 389           gimple *g = gimple_expand_vec_cond_expr (fun, &gsi,
 390                                                    &vec_cond_ssa_name_uses);
 391           if (g != NULL)
 392             {
 393               tree lhs = gimple_assign_lhs (gsi_stmt (gsi));
 394               gimple_set_lhs (g, lhs);
 395               gsi_replace (&gsi, g, false);
 396             }
 397
 398           /* Recognize .VEC_SET and .VEC_EXTRACT patterns.  */
 399           cfg_changed |= gimple_expand_vec_set_extract_expr (fun, &gsi);
 400           if (gsi_end_p (gsi))
 401             break;
 402
 403           gassign *stmt = dyn_cast <gassign *> (*gsi);
 404           if (!stmt)
 405             continue;
 406
 407           tree_code code = gimple_assign_rhs_code (stmt);
 408           tree lhs = gimple_assign_lhs (stmt);
 409           if (TREE_CODE_CLASS (code) == tcc_comparison
 410               && !has_single_use (lhs))
 411             {
 412               /* Duplicate COND_EXPR condition defs when they are
 413                  comparisons so RTL expansion with the help of TER
 414                  can perform better if conversion.  */
 415               imm_use_iterator imm_iter;
 416               use_operand_p use_p;
 417               auto_vec<gassign *, 4> cond_exprs;
 418               unsigned cnt = 0;
 419               FOR_EACH_IMM_USE_FAST (use_p, imm_iter, lhs)
 420                 {
 421                   if (is_gimple_debug (USE_STMT (use_p)))
 422                     continue;
 423                   cnt++;
 424                   if (gimple_bb (USE_STMT (use_p)) == bb
 425                       && is_gimple_assign (USE_STMT (use_p))
 426                       && gimple_assign_rhs1_ptr (USE_STMT (use_p)) == use_p->use
 427                       && gimple_assign_rhs_code (USE_STMT (use_p)) == COND_EXPR)
 428                     cond_exprs.safe_push (as_a <gassign *> (USE_STMT (use_p)));
 429                 }
 430               for (unsigned i = cond_exprs.length () == cnt ? 1 : 0;
 431                    i < cond_exprs.length (); ++i)
 432                 {
 433                   gassign *copy = as_a <gassign *> (gimple_copy (stmt));
 434                   tree new_def = duplicate_ssa_name (lhs, copy);
 435                   gimple_assign_set_lhs (copy, new_def);
 436                   auto gsi2 = gsi_for_stmt (cond_exprs[i]);
 437                   gsi_insert_before (&gsi2, copy, GSI_SAME_STMT);
 438                   gimple_assign_set_rhs1 (cond_exprs[i], new_def);
 439                   update_stmt (cond_exprs[i]);
 440                 }
 441             }
 442         }
 443     }
 444
 445   for (auto it = vec_cond_ssa_name_uses.begin ();
 446        it != vec_cond_ssa_name_uses.end (); ++it)
 447     bitmap_set_bit (dce_ssa_names, SSA_NAME_VERSION ((*it).first));
 448
 449   simple_dce_from_worklist (dce_ssa_names);
 450
 451   return cfg_changed ? TODO_cleanup_cfg : 0;
 452 }
 453
 454 } // anon namespace
 455
 456 gimple_opt_pass *
 457 make_pass_gimple_isel (gcc::context *ctxt)
 458 {
 459   return new pass_gimple_isel (ctxt);
 460 }
 461