| 1 | /* Switch Conversion converts variable initializations based on switch |
| 2 | statements to initializations from a static array. |
| 3 | Copyright (C) 2006, 2008 Free Software Foundation, Inc. |
| 4 | Contributed by Martin Jambor <jamborm@suse.cz> |
| 5 | |
| 6 | This file is part of GCC. |
| 7 | |
| 8 | GCC is free software; you can redistribute it and/or modify it |
| 9 | under the terms of the GNU General Public License as published by the |
| 10 | Free Software Foundation; either version 3, or (at your option) any |
| 11 | later version. |
| 12 | |
| 13 | GCC is distributed in the hope that it will be useful, but WITHOUT |
| 14 | ANY 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, write to the Free |
| 20 | Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA |
| 21 | 02110-1301, USA. */ |
| 22 | |
| 23 | /* |
| 24 | Switch initialization conversion |
| 25 | |
| 26 | The following pass changes simple initializations of scalars in a switch |
| 27 | statement into initializations from a static array. Obviously, the values must |
| 28 | be constant and known at compile time and a default branch must be |
| 29 | provided. For example, the following code: |
| 30 | |
| 31 | int a,b; |
| 32 | |
| 33 | switch (argc) |
| 34 | { |
| 35 | case 1: |
| 36 | case 2: |
| 37 | a_1 = 8; |
| 38 | b_1 = 6; |
| 39 | break; |
| 40 | case 3: |
| 41 | a_2 = 9; |
| 42 | b_2 = 5; |
| 43 | break; |
| 44 | case 12: |
| 45 | a_3 = 10; |
| 46 | b_3 = 4; |
| 47 | break; |
| 48 | default: |
| 49 | a_4 = 16; |
| 50 | b_4 = 1; |
| 51 | } |
| 52 | a_5 = PHI <a_1, a_2, a_3, a_4> |
| 53 | b_5 = PHI <b_1, b_2, b_3, b_4> |
| 54 | |
| 55 | |
| 56 | is changed into: |
| 57 | |
| 58 | static const int = CSWTCH01[] = {6, 6, 5, 1, 1, 1, 1, 1, 1, 1, 1, 4}; |
| 59 | static const int = CSWTCH02[] = {8, 8, 9, 16, 16, 16, 16, 16, 16, 16, |
| 60 | 16, 16, 10}; |
| 61 | |
| 62 | if (((unsigned) argc) - 1 < 11) |
| 63 | { |
| 64 | a_6 = CSWTCH02[argc - 1]; |
| 65 | b_6 = CSWTCH01[argc - 1]; |
| 66 | } |
| 67 | else |
| 68 | { |
| 69 | a_7 = 16; |
| 70 | b_7 = 1; |
| 71 | } |
| 72 | a_5 = PHI <a_6, a_7> |
| 73 | b_b = PHI <b_6, b_7> |
| 74 | |
| 75 | There are further constraints. Specifically, the range of values across all |
| 76 | case labels must not be bigger than SWITCH_CONVERSION_BRANCH_RATIO (default |
| 77 | eight) times the number of the actual switch branches. */ |
| 78 | |
| 79 | #include "config.h" |
| 80 | #include "system.h" |
| 81 | #include "coretypes.h" |
| 82 | #include "tm.h" |
| 83 | #include <signal.h> |
| 84 | |
| 85 | #include "line-map.h" |
| 86 | #include "params.h" |
| 87 | #include "flags.h" |
| 88 | #include "tree.h" |
| 89 | #include "basic-block.h" |
| 90 | #include "tree-flow.h" |
| 91 | #include "tree-flow-inline.h" |
| 92 | #include "tree-ssa-operands.h" |
| 93 | #include "output.h" |
| 94 | #include "input.h" |
| 95 | #include "tree-pass.h" |
| 96 | #include "diagnostic.h" |
| 97 | #include "tree-dump.h" |
| 98 | #include "timevar.h" |
| 99 | #include "langhooks.h" |
| 100 | |
| 101 | /* The main structure of the pass. */ |
| 102 | struct switch_conv_info |
| 103 | { |
| 104 | /* The expression used to decide the switch branch. (It is subsequently used |
| 105 | as the index to the created array.) */ |
| 106 | tree index_expr; |
| 107 | |
| 108 | /* The following integer constants store the minimum value covered by the |
| 109 | cases. */ |
| 110 | tree range_min; |
| 111 | |
| 112 | /* The difference between the above two numbers, i.e. The size of the array |
| 113 | that would have to be created by the transformation. */ |
| 114 | tree range_size; |
| 115 | |
| 116 | /* Basic block that contains the actual SWITCH_EXPR. */ |
| 117 | basic_block switch_bb; |
| 118 | |
| 119 | /* All branches of the switch statement must have a single successor stored in |
| 120 | the following variable. */ |
| 121 | basic_block final_bb; |
| 122 | |
| 123 | /* Number of phi nodes in the final bb (that we'll be replacing). */ |
| 124 | int phi_count; |
| 125 | |
| 126 | /* Array of default values, in the same order as phi nodes. */ |
| 127 | tree *default_values; |
| 128 | |
| 129 | /* Constructors of new static arrays. */ |
| 130 | VEC (constructor_elt, gc) **constructors; |
| 131 | |
| 132 | /* Array of ssa names that are initialized with a value from a new static |
| 133 | array. */ |
| 134 | tree *target_inbound_names; |
| 135 | |
| 136 | /* Array of ssa names that are initialized with the default value if the |
| 137 | switch expression is out of range. */ |
| 138 | tree *target_outbound_names; |
| 139 | |
| 140 | /* The probability of the default edge in the replaced switch. */ |
| 141 | int default_prob; |
| 142 | |
| 143 | /* The count of the default edge in the replaced switch. */ |
| 144 | gcov_type default_count; |
| 145 | |
| 146 | /* Combined count of all other (non-default) edges in the replaced switch. */ |
| 147 | gcov_type other_count; |
| 148 | |
| 149 | /* The first load statement that loads a temporary from a new static array. |
| 150 | */ |
| 151 | gimple arr_ref_first; |
| 152 | |
| 153 | /* The last load statement that loads a temporary from a new static array. */ |
| 154 | gimple arr_ref_last; |
| 155 | |
| 156 | /* String reason why the case wasn't a good candidate that is written to the |
| 157 | dump file, if there is one. */ |
| 158 | const char *reason; |
| 159 | }; |
| 160 | |
| 161 | /* Global pass info. */ |
| 162 | static struct switch_conv_info info; |
| 163 | |
| 164 | |
| 165 | /* Checks whether the range given by individual case statements of the SWTCH |
| 166 | switch statement isn't too big and whether the number of branches actually |
| 167 | satisfies the size of the new array. */ |
| 168 | |
| 169 | static bool |
| 170 | check_range (gimple swtch) |
| 171 | { |
| 172 | tree min_case, max_case; |
| 173 | unsigned int branch_num = gimple_switch_num_labels (swtch); |
| 174 | tree range_max; |
| 175 | |
| 176 | /* The gimplifier has already sorted the cases by CASE_LOW and ensured there |
| 177 | is a default label which is the last in the vector. */ |
| 178 | |
| 179 | min_case = gimple_switch_label (swtch, 1); |
| 180 | info.range_min = CASE_LOW (min_case); |
| 181 | |
| 182 | gcc_assert (branch_num > 1); |
| 183 | gcc_assert (CASE_LOW (gimple_switch_label (swtch, 0)) == NULL_TREE); |
| 184 | max_case = gimple_switch_label (swtch, branch_num - 1); |
| 185 | if (CASE_HIGH (max_case) != NULL_TREE) |
| 186 | range_max = CASE_HIGH (max_case); |
| 187 | else |
| 188 | range_max = CASE_LOW (max_case); |
| 189 | |
| 190 | gcc_assert (info.range_min); |
| 191 | gcc_assert (range_max); |
| 192 | |
| 193 | info.range_size = int_const_binop (MINUS_EXPR, range_max, info.range_min, 0); |
| 194 | |
| 195 | gcc_assert (info.range_size); |
| 196 | if (!host_integerp (info.range_size, 1)) |
| 197 | { |
| 198 | info.reason = "index range way too large or otherwise unusable.\n"; |
| 199 | return false; |
| 200 | } |
| 201 | |
| 202 | if ((unsigned HOST_WIDE_INT) tree_low_cst (info.range_size, 1) |
| 203 | > ((unsigned) branch_num * SWITCH_CONVERSION_BRANCH_RATIO)) |
| 204 | { |
| 205 | info.reason = "the maximum range-branch ratio exceeded.\n"; |
| 206 | return false; |
| 207 | } |
| 208 | |
| 209 | return true; |
| 210 | } |
| 211 | |
| 212 | /* Checks the given CS switch case whether it is suitable for conversion |
| 213 | (whether all but the default basic blocks are empty and so on). If it is, |
| 214 | adds the case to the branch list along with values for the defined variables |
| 215 | and returns true. Otherwise returns false. */ |
| 216 | |
| 217 | static bool |
| 218 | check_process_case (tree cs) |
| 219 | { |
| 220 | tree ldecl; |
| 221 | basic_block label_bb, following_bb; |
| 222 | edge e; |
| 223 | |
| 224 | ldecl = CASE_LABEL (cs); |
| 225 | label_bb = label_to_block (ldecl); |
| 226 | |
| 227 | e = find_edge (info.switch_bb, label_bb); |
| 228 | gcc_assert (e); |
| 229 | |
| 230 | if (CASE_LOW (cs) == NULL_TREE) |
| 231 | { |
| 232 | /* Default branch. */ |
| 233 | info.default_prob = e->probability; |
| 234 | info.default_count = e->count; |
| 235 | } |
| 236 | else |
| 237 | info.other_count += e->count; |
| 238 | |
| 239 | if (!label_bb) |
| 240 | { |
| 241 | info.reason = " Bad case - cs BB label is NULL\n"; |
| 242 | return false; |
| 243 | } |
| 244 | |
| 245 | if (!single_pred_p (label_bb)) |
| 246 | { |
| 247 | if (info.final_bb && info.final_bb != label_bb) |
| 248 | { |
| 249 | info.reason = " Bad case - a non-final BB has two predecessors\n"; |
| 250 | return false; /* sth complex going on in this branch */ |
| 251 | } |
| 252 | |
| 253 | following_bb = label_bb; |
| 254 | } |
| 255 | else |
| 256 | { |
| 257 | if (!empty_block_p (label_bb)) |
| 258 | { |
| 259 | info.reason = " Bad case - a non-final BB not empty\n"; |
| 260 | return false; |
| 261 | } |
| 262 | |
| 263 | e = single_succ_edge (label_bb); |
| 264 | following_bb = single_succ (label_bb); |
| 265 | } |
| 266 | |
| 267 | if (!info.final_bb) |
| 268 | info.final_bb = following_bb; |
| 269 | else if (info.final_bb != following_bb) |
| 270 | { |
| 271 | info.reason = " Bad case - different final BB\n"; |
| 272 | return false; /* the only successor is not common for all the branches */ |
| 273 | } |
| 274 | |
| 275 | return true; |
| 276 | } |
| 277 | |
| 278 | /* This function checks whether all required values in phi nodes in final_bb |
| 279 | are constants. Required values are those that correspond to a basic block |
| 280 | which is a part of the examined switch statement. It returns true if the |
| 281 | phi nodes are OK, otherwise false. */ |
| 282 | |
| 283 | static bool |
| 284 | check_final_bb (void) |
| 285 | { |
| 286 | gimple_stmt_iterator gsi; |
| 287 | |
| 288 | info.phi_count = 0; |
| 289 | for (gsi = gsi_start_phis (info.final_bb); !gsi_end_p (gsi); gsi_next (&gsi)) |
| 290 | { |
| 291 | gimple phi = gsi_stmt (gsi); |
| 292 | unsigned int i; |
| 293 | |
| 294 | info.phi_count++; |
| 295 | |
| 296 | for (i = 0; i < gimple_phi_num_args (phi); i++) |
| 297 | { |
| 298 | basic_block bb = gimple_phi_arg_edge (phi, i)->src; |
| 299 | |
| 300 | if (bb == info.switch_bb |
| 301 | || (single_pred_p (bb) && single_pred (bb) == info.switch_bb)) |
| 302 | { |
| 303 | tree reloc, val; |
| 304 | |
| 305 | val = gimple_phi_arg_def (phi, i); |
| 306 | if (!is_gimple_ip_invariant (val)) |
| 307 | { |
| 308 | info.reason = " Non-invariant value from a case\n"; |
| 309 | return false; /* Non-invariant argument. */ |
| 310 | } |
| 311 | reloc = initializer_constant_valid_p (val, TREE_TYPE (val)); |
| 312 | if ((flag_pic && reloc != null_pointer_node) |
| 313 | || (!flag_pic && reloc == NULL_TREE)) |
| 314 | { |
| 315 | if (reloc) |
| 316 | info.reason |
| 317 | = " Value from a case would need runtime relocations\n"; |
| 318 | else |
| 319 | info.reason |
| 320 | = " Value from a case is not a valid initializer\n"; |
| 321 | return false; |
| 322 | } |
| 323 | } |
| 324 | } |
| 325 | } |
| 326 | |
| 327 | return true; |
| 328 | } |
| 329 | |
| 330 | /* The following function allocates default_values, target_{in,out}_names and |
| 331 | constructors arrays. The last one is also populated with pointers to |
| 332 | vectors that will become constructors of new arrays. */ |
| 333 | |
| 334 | static void |
| 335 | create_temp_arrays (void) |
| 336 | { |
| 337 | int i; |
| 338 | |
| 339 | info.default_values = (tree *) xcalloc (info.phi_count, sizeof (tree)); |
| 340 | info.constructors = (VEC (constructor_elt, gc) **) xcalloc (info.phi_count, |
| 341 | sizeof (tree)); |
| 342 | info.target_inbound_names = (tree *) xcalloc (info.phi_count, sizeof (tree)); |
| 343 | info.target_outbound_names = (tree *) xcalloc (info.phi_count, |
| 344 | sizeof (tree)); |
| 345 | |
| 346 | for (i = 0; i < info.phi_count; i++) |
| 347 | info.constructors[i] |
| 348 | = VEC_alloc (constructor_elt, gc, tree_low_cst (info.range_size, 1) + 1); |
| 349 | } |
| 350 | |
| 351 | /* Free the arrays created by create_temp_arrays(). The vectors that are |
| 352 | created by that function are not freed here, however, because they have |
| 353 | already become constructors and must be preserved. */ |
| 354 | |
| 355 | static void |
| 356 | free_temp_arrays (void) |
| 357 | { |
| 358 | free (info.constructors); |
| 359 | free (info.default_values); |
| 360 | free (info.target_inbound_names); |
| 361 | free (info.target_outbound_names); |
| 362 | } |
| 363 | |
| 364 | /* Populate the array of default values in the order of phi nodes. |
| 365 | DEFAULT_CASE is the CASE_LABEL_EXPR for the default switch branch. */ |
| 366 | |
| 367 | static void |
| 368 | gather_default_values (tree default_case) |
| 369 | { |
| 370 | gimple_stmt_iterator gsi; |
| 371 | basic_block bb = label_to_block (CASE_LABEL (default_case)); |
| 372 | edge e; |
| 373 | int i = 0; |
| 374 | |
| 375 | gcc_assert (CASE_LOW (default_case) == NULL_TREE); |
| 376 | |
| 377 | if (bb == info.final_bb) |
| 378 | e = find_edge (info.switch_bb, bb); |
| 379 | else |
| 380 | e = single_succ_edge (bb); |
| 381 | |
| 382 | for (gsi = gsi_start_phis (info.final_bb); !gsi_end_p (gsi); gsi_next (&gsi)) |
| 383 | { |
| 384 | gimple phi = gsi_stmt (gsi); |
| 385 | tree val = PHI_ARG_DEF_FROM_EDGE (phi, e); |
| 386 | gcc_assert (val); |
| 387 | info.default_values[i++] = val; |
| 388 | } |
| 389 | } |
| 390 | |
| 391 | /* The following function populates the vectors in the constructors array with |
| 392 | future contents of the static arrays. The vectors are populated in the |
| 393 | order of phi nodes. SWTCH is the switch statement being converted. */ |
| 394 | |
| 395 | static void |
| 396 | build_constructors (gimple swtch) |
| 397 | { |
| 398 | unsigned i, branch_num = gimple_switch_num_labels (swtch); |
| 399 | tree pos = info.range_min; |
| 400 | |
| 401 | for (i = 1; i < branch_num; i++) |
| 402 | { |
| 403 | tree cs = gimple_switch_label (swtch, i); |
| 404 | basic_block bb = label_to_block (CASE_LABEL (cs)); |
| 405 | edge e; |
| 406 | tree high; |
| 407 | gimple_stmt_iterator gsi; |
| 408 | int j; |
| 409 | |
| 410 | if (bb == info.final_bb) |
| 411 | e = find_edge (info.switch_bb, bb); |
| 412 | else |
| 413 | e = single_succ_edge (bb); |
| 414 | gcc_assert (e); |
| 415 | |
| 416 | while (tree_int_cst_lt (pos, CASE_LOW (cs))) |
| 417 | { |
| 418 | int k; |
| 419 | for (k = 0; k < info.phi_count; k++) |
| 420 | { |
| 421 | constructor_elt *elt; |
| 422 | |
| 423 | elt = VEC_quick_push (constructor_elt, |
| 424 | info.constructors[k], NULL); |
| 425 | elt->index = int_const_binop (MINUS_EXPR, pos, |
| 426 | info.range_min, 0); |
| 427 | elt->value = info.default_values[k]; |
| 428 | } |
| 429 | |
| 430 | pos = int_const_binop (PLUS_EXPR, pos, integer_one_node, 0); |
| 431 | } |
| 432 | gcc_assert (tree_int_cst_equal (pos, CASE_LOW (cs))); |
| 433 | |
| 434 | j = 0; |
| 435 | if (CASE_HIGH (cs)) |
| 436 | high = CASE_HIGH (cs); |
| 437 | else |
| 438 | high = CASE_LOW (cs); |
| 439 | for (gsi = gsi_start_phis (info.final_bb); |
| 440 | !gsi_end_p (gsi); gsi_next (&gsi)) |
| 441 | { |
| 442 | gimple phi = gsi_stmt (gsi); |
| 443 | tree val = PHI_ARG_DEF_FROM_EDGE (phi, e); |
| 444 | tree low = CASE_LOW (cs); |
| 445 | pos = CASE_LOW (cs); |
| 446 | |
| 447 | do |
| 448 | { |
| 449 | constructor_elt *elt; |
| 450 | |
| 451 | elt = VEC_quick_push (constructor_elt, |
| 452 | info.constructors[j], NULL); |
| 453 | elt->index = int_const_binop (MINUS_EXPR, pos, info.range_min, 0); |
| 454 | elt->value = val; |
| 455 | |
| 456 | pos = int_const_binop (PLUS_EXPR, pos, integer_one_node, 0); |
| 457 | } while (!tree_int_cst_lt (high, pos) && tree_int_cst_lt (low, pos)); |
| 458 | j++; |
| 459 | } |
| 460 | } |
| 461 | } |
| 462 | |
| 463 | /* Create an appropriate array type and declaration and assemble a static array |
| 464 | variable. Also create a load statement that initializes the variable in |
| 465 | question with a value from the static array. SWTCH is the switch statement |
| 466 | being converted, NUM is the index to arrays of constructors, default values |
| 467 | and target SSA names for this particular array. ARR_INDEX_TYPE is the type |
| 468 | of the index of the new array, PHI is the phi node of the final BB that |
| 469 | corresponds to the value that will be loaded from the created array. TIDX |
| 470 | is a temporary variable holding the index for loads from the new array. */ |
| 471 | |
| 472 | static void |
| 473 | build_one_array (gimple swtch, int num, tree arr_index_type, gimple phi, |
| 474 | tree tidx) |
| 475 | { |
| 476 | tree array_type, ctor, decl, value_type, name, fetch; |
| 477 | gimple load; |
| 478 | gimple_stmt_iterator gsi; |
| 479 | |
| 480 | gcc_assert (info.default_values[num]); |
| 481 | value_type = TREE_TYPE (info.default_values[num]); |
| 482 | array_type = build_array_type (value_type, arr_index_type); |
| 483 | |
| 484 | ctor = build_constructor (array_type, info.constructors[num]); |
| 485 | TREE_CONSTANT (ctor) = true; |
| 486 | |
| 487 | decl = build_decl (VAR_DECL, NULL_TREE, array_type); |
| 488 | TREE_STATIC (decl) = 1; |
| 489 | DECL_INITIAL (decl) = ctor; |
| 490 | |
| 491 | DECL_NAME (decl) = create_tmp_var_name ("CSWTCH"); |
| 492 | DECL_ARTIFICIAL (decl) = 1; |
| 493 | TREE_CONSTANT (decl) = 1; |
| 494 | add_referenced_var (decl); |
| 495 | varpool_mark_needed_node (varpool_node (decl)); |
| 496 | varpool_finalize_decl (decl); |
| 497 | mark_sym_for_renaming (decl); |
| 498 | |
| 499 | name = make_ssa_name (SSA_NAME_VAR (PHI_RESULT (phi)), NULL); |
| 500 | info.target_inbound_names[num] = name; |
| 501 | |
| 502 | fetch = build4 (ARRAY_REF, value_type, decl, tidx, NULL_TREE, |
| 503 | NULL_TREE); |
| 504 | load = gimple_build_assign (name, fetch); |
| 505 | SSA_NAME_DEF_STMT (name) = load; |
| 506 | |
| 507 | gsi = gsi_for_stmt (swtch); |
| 508 | gsi_insert_before (&gsi, load, GSI_SAME_STMT); |
| 509 | mark_symbols_for_renaming (load); |
| 510 | |
| 511 | info.arr_ref_last = load; |
| 512 | } |
| 513 | |
| 514 | /* Builds and initializes static arrays initialized with values gathered from |
| 515 | the SWTCH switch statement. Also creates statements that load values from |
| 516 | them. */ |
| 517 | |
| 518 | static void |
| 519 | build_arrays (gimple swtch) |
| 520 | { |
| 521 | tree arr_index_type; |
| 522 | tree tidx, sub; |
| 523 | gimple stmt; |
| 524 | gimple_stmt_iterator gsi; |
| 525 | int i; |
| 526 | |
| 527 | gsi = gsi_for_stmt (swtch); |
| 528 | |
| 529 | arr_index_type = build_index_type (info.range_size); |
| 530 | tidx = make_rename_temp (arr_index_type, "csti"); |
| 531 | sub = fold_build2 (MINUS_EXPR, TREE_TYPE (info.index_expr), info.index_expr, |
| 532 | fold_convert (TREE_TYPE (info.index_expr), |
| 533 | info.range_min)); |
| 534 | sub = force_gimple_operand_gsi (&gsi, fold_convert (arr_index_type, sub), |
| 535 | false, NULL, true, GSI_SAME_STMT); |
| 536 | stmt = gimple_build_assign (tidx, sub); |
| 537 | |
| 538 | gsi_insert_before (&gsi, stmt, GSI_SAME_STMT); |
| 539 | mark_symbols_for_renaming (stmt); |
| 540 | info.arr_ref_first = stmt; |
| 541 | |
| 542 | for (gsi = gsi_start_phis (info.final_bb), i = 0; |
| 543 | !gsi_end_p (gsi); gsi_next (&gsi), i++) |
| 544 | build_one_array (swtch, i, arr_index_type, gsi_stmt (gsi), tidx); |
| 545 | } |
| 546 | |
| 547 | /* Generates and appropriately inserts loads of default values at the position |
| 548 | given by BSI. Returns the last inserted statement. */ |
| 549 | |
| 550 | static gimple |
| 551 | gen_def_assigns (gimple_stmt_iterator *gsi) |
| 552 | { |
| 553 | int i; |
| 554 | gimple assign = NULL; |
| 555 | |
| 556 | for (i = 0; i < info.phi_count; i++) |
| 557 | { |
| 558 | tree name |
| 559 | = make_ssa_name (SSA_NAME_VAR (info.target_inbound_names[i]), NULL); |
| 560 | |
| 561 | info.target_outbound_names[i] = name; |
| 562 | assign = gimple_build_assign (name, info.default_values[i]); |
| 563 | SSA_NAME_DEF_STMT (name) = assign; |
| 564 | gsi_insert_before (gsi, assign, GSI_SAME_STMT); |
| 565 | find_new_referenced_vars (assign); |
| 566 | mark_symbols_for_renaming (assign); |
| 567 | } |
| 568 | return assign; |
| 569 | } |
| 570 | |
| 571 | /* Deletes the unused bbs and edges that now contain the switch statement and |
| 572 | its empty branch bbs. BBD is the now dead BB containing the original switch |
| 573 | statement, FINAL is the last BB of the converted switch statement (in terms |
| 574 | of succession). */ |
| 575 | |
| 576 | static void |
| 577 | prune_bbs (basic_block bbd, basic_block final) |
| 578 | { |
| 579 | edge_iterator ei; |
| 580 | edge e; |
| 581 | |
| 582 | for (ei = ei_start (bbd->succs); (e = ei_safe_edge (ei)); ) |
| 583 | { |
| 584 | basic_block bb; |
| 585 | bb = e->dest; |
| 586 | remove_edge (e); |
| 587 | if (bb != final) |
| 588 | delete_basic_block (bb); |
| 589 | } |
| 590 | delete_basic_block (bbd); |
| 591 | } |
| 592 | |
| 593 | /* Add values to phi nodes in final_bb for the two new edges. E1F is the edge |
| 594 | from the basic block loading values from an array and E2F from the basic |
| 595 | block loading default values. BBF is the last switch basic block (see the |
| 596 | bbf description in the comment below). */ |
| 597 | |
| 598 | static void |
| 599 | fix_phi_nodes (edge e1f, edge e2f, basic_block bbf) |
| 600 | { |
| 601 | gimple_stmt_iterator gsi; |
| 602 | int i; |
| 603 | |
| 604 | for (gsi = gsi_start_phis (bbf), i = 0; |
| 605 | !gsi_end_p (gsi); gsi_next (&gsi), i++) |
| 606 | { |
| 607 | gimple phi = gsi_stmt (gsi); |
| 608 | add_phi_arg (phi, info.target_inbound_names[i], e1f); |
| 609 | add_phi_arg (phi, info.target_outbound_names[i], e2f); |
| 610 | } |
| 611 | |
| 612 | } |
| 613 | |
| 614 | /* Creates a check whether the switch expression value actually falls into the |
| 615 | range given by all the cases. If it does not, the temporaries are loaded |
| 616 | with default values instead. SWTCH is the switch statement being converted. |
| 617 | |
| 618 | bb0 is the bb with the switch statement, however, we'll end it with a |
| 619 | condition instead. |
| 620 | |
| 621 | bb1 is the bb to be used when the range check went ok. It is derived from |
| 622 | the switch BB |
| 623 | |
| 624 | bb2 is the bb taken when the expression evaluated outside of the range |
| 625 | covered by the created arrays. It is populated by loads of default |
| 626 | values. |
| 627 | |
| 628 | bbF is a fall through for both bb1 and bb2 and contains exactly what |
| 629 | originally followed the switch statement. |
| 630 | |
| 631 | bbD contains the switch statement (in the end). It is unreachable but we |
| 632 | still need to strip off its edges. |
| 633 | */ |
| 634 | |
| 635 | static void |
| 636 | gen_inbound_check (gimple swtch) |
| 637 | { |
| 638 | tree label_decl1 = create_artificial_label (); |
| 639 | tree label_decl2 = create_artificial_label (); |
| 640 | tree label_decl3 = create_artificial_label (); |
| 641 | gimple label1, label2, label3; |
| 642 | |
| 643 | tree utype; |
| 644 | tree tmp_u; |
| 645 | tree cast; |
| 646 | gimple cast_assign, minus_assign; |
| 647 | tree ulb, minus; |
| 648 | tree bound; |
| 649 | |
| 650 | gimple cond_stmt; |
| 651 | |
| 652 | gimple last_assign; |
| 653 | gimple_stmt_iterator gsi; |
| 654 | basic_block bb0, bb1, bb2, bbf, bbd; |
| 655 | edge e01, e02, e21, e1d, e1f, e2f; |
| 656 | |
| 657 | gcc_assert (info.default_values); |
| 658 | bb0 = gimple_bb (swtch); |
| 659 | |
| 660 | /* Make sure we do not generate arithmetics in a subrange. */ |
| 661 | if (TREE_TYPE (TREE_TYPE (info.index_expr))) |
| 662 | utype = lang_hooks.types.type_for_mode |
| 663 | (TYPE_MODE (TREE_TYPE (TREE_TYPE (info.index_expr))), 1); |
| 664 | else |
| 665 | utype = lang_hooks.types.type_for_mode |
| 666 | (TYPE_MODE (TREE_TYPE (info.index_expr)), 1); |
| 667 | |
| 668 | /* (end of) block 0 */ |
| 669 | gsi = gsi_for_stmt (info.arr_ref_first); |
| 670 | tmp_u = make_rename_temp (utype, "csui"); |
| 671 | |
| 672 | cast = fold_convert (utype, info.index_expr); |
| 673 | cast_assign = gimple_build_assign (tmp_u, cast); |
| 674 | find_new_referenced_vars (cast_assign); |
| 675 | gsi_insert_before (&gsi, cast_assign, GSI_SAME_STMT); |
| 676 | mark_symbols_for_renaming (cast_assign); |
| 677 | |
| 678 | ulb = fold_convert (utype, info.range_min); |
| 679 | minus = fold_build2 (MINUS_EXPR, utype, tmp_u, ulb); |
| 680 | minus = force_gimple_operand_gsi (&gsi, minus, false, NULL, true, |
| 681 | GSI_SAME_STMT); |
| 682 | minus_assign = gimple_build_assign (tmp_u, minus); |
| 683 | find_new_referenced_vars (minus_assign); |
| 684 | gsi_insert_before (&gsi, minus_assign, GSI_SAME_STMT); |
| 685 | mark_symbols_for_renaming (minus_assign); |
| 686 | |
| 687 | bound = fold_convert (utype, info.range_size); |
| 688 | |
| 689 | cond_stmt = gimple_build_cond (LE_EXPR, tmp_u, bound, NULL_TREE, NULL_TREE); |
| 690 | |
| 691 | find_new_referenced_vars (cond_stmt); |
| 692 | gsi_insert_before (&gsi, cond_stmt, GSI_SAME_STMT); |
| 693 | mark_symbols_for_renaming (cond_stmt); |
| 694 | |
| 695 | /* block 2 */ |
| 696 | gsi = gsi_for_stmt (info.arr_ref_first); |
| 697 | label2 = gimple_build_label (label_decl2); |
| 698 | gsi_insert_before (&gsi, label2, GSI_SAME_STMT); |
| 699 | last_assign = gen_def_assigns (&gsi); |
| 700 | |
| 701 | /* block 1 */ |
| 702 | gsi = gsi_for_stmt (info.arr_ref_first); |
| 703 | label1 = gimple_build_label (label_decl1); |
| 704 | gsi_insert_before (&gsi, label1, GSI_SAME_STMT); |
| 705 | |
| 706 | /* block F */ |
| 707 | gsi = gsi_start_bb (info.final_bb); |
| 708 | label3 = gimple_build_label (label_decl3); |
| 709 | gsi_insert_before (&gsi, label3, GSI_SAME_STMT); |
| 710 | |
| 711 | /* cfg fix */ |
| 712 | e02 = split_block (bb0, cond_stmt); |
| 713 | bb2 = e02->dest; |
| 714 | |
| 715 | e21 = split_block (bb2, last_assign); |
| 716 | bb1 = e21->dest; |
| 717 | remove_edge (e21); |
| 718 | |
| 719 | e1d = split_block (bb1, info.arr_ref_last); |
| 720 | bbd = e1d->dest; |
| 721 | remove_edge (e1d); |
| 722 | |
| 723 | /* flags and profiles of the edge for in-range values */ |
| 724 | e01 = make_edge (bb0, bb1, EDGE_TRUE_VALUE); |
| 725 | e01->probability = REG_BR_PROB_BASE - info.default_prob; |
| 726 | e01->count = info.other_count; |
| 727 | |
| 728 | /* flags and profiles of the edge taking care of out-of-range values */ |
| 729 | e02->flags &= ~EDGE_FALLTHRU; |
| 730 | e02->flags |= EDGE_FALSE_VALUE; |
| 731 | e02->probability = info.default_prob; |
| 732 | e02->count = info.default_count; |
| 733 | |
| 734 | bbf = info.final_bb; |
| 735 | |
| 736 | e1f = make_edge (bb1, bbf, EDGE_FALLTHRU); |
| 737 | e1f->probability = REG_BR_PROB_BASE; |
| 738 | e1f->count = info.other_count; |
| 739 | |
| 740 | e2f = make_edge (bb2, bbf, EDGE_FALLTHRU); |
| 741 | e2f->probability = REG_BR_PROB_BASE; |
| 742 | e2f->count = info.default_count; |
| 743 | |
| 744 | /* frequencies of the new BBs */ |
| 745 | bb1->frequency = EDGE_FREQUENCY (e01); |
| 746 | bb2->frequency = EDGE_FREQUENCY (e02); |
| 747 | bbf->frequency = EDGE_FREQUENCY (e1f) + EDGE_FREQUENCY (e2f); |
| 748 | |
| 749 | prune_bbs (bbd, info.final_bb); /* To keep calc_dfs_tree() in dominance.c |
| 750 | happy. */ |
| 751 | |
| 752 | fix_phi_nodes (e1f, e2f, bbf); |
| 753 | |
| 754 | free_dominance_info (CDI_DOMINATORS); |
| 755 | free_dominance_info (CDI_POST_DOMINATORS); |
| 756 | } |
| 757 | |
| 758 | /* The following function is invoked on every switch statement (the current one |
| 759 | is given in SWTCH) and runs the individual phases of switch conversion on it |
| 760 | one after another until one fails or the conversion is completed. */ |
| 761 | |
| 762 | static bool |
| 763 | process_switch (gimple swtch) |
| 764 | { |
| 765 | unsigned int i, branch_num = gimple_switch_num_labels (swtch); |
| 766 | tree index_type; |
| 767 | |
| 768 | /* Operand 2 is either NULL_TREE or a vector of cases (stmt.c). */ |
| 769 | if (branch_num < 2) |
| 770 | { |
| 771 | info.reason = "switch has no labels\n"; |
| 772 | return false; |
| 773 | } |
| 774 | |
| 775 | info.final_bb = NULL; |
| 776 | info.switch_bb = gimple_bb (swtch); |
| 777 | info.index_expr = gimple_switch_index (swtch); |
| 778 | index_type = TREE_TYPE (info.index_expr); |
| 779 | info.arr_ref_first = NULL; |
| 780 | info.arr_ref_last = NULL; |
| 781 | info.default_prob = 0; |
| 782 | info.default_count = 0; |
| 783 | info.other_count = 0; |
| 784 | |
| 785 | /* An ERROR_MARK occurs for various reasons including invalid data type. |
| 786 | (comment from stmt.c) */ |
| 787 | if (index_type == error_mark_node) |
| 788 | { |
| 789 | info.reason = "index error.\n"; |
| 790 | return false; |
| 791 | } |
| 792 | |
| 793 | /* Check the case label values are within reasonable range: */ |
| 794 | if (!check_range (swtch)) |
| 795 | return false; |
| 796 | |
| 797 | /* For all the cases, see whether they are empty, the assignments they |
| 798 | represent constant and so on... */ |
| 799 | for (i = 0; i < branch_num; i++) |
| 800 | if (!check_process_case (gimple_switch_label (swtch, i))) |
| 801 | { |
| 802 | if (dump_file) |
| 803 | fprintf (dump_file, "Processing of case %i failed\n", i); |
| 804 | return false; |
| 805 | } |
| 806 | |
| 807 | if (!check_final_bb ()) |
| 808 | return false; |
| 809 | |
| 810 | /* At this point all checks have passed and we can proceed with the |
| 811 | transformation. */ |
| 812 | |
| 813 | create_temp_arrays (); |
| 814 | gather_default_values (gimple_switch_label (swtch, 0)); |
| 815 | build_constructors (swtch); |
| 816 | |
| 817 | build_arrays (swtch); /* Build the static arrays and assignments. */ |
| 818 | gen_inbound_check (swtch); /* Build the bounds check. */ |
| 819 | |
| 820 | /* Cleanup: */ |
| 821 | free_temp_arrays (); |
| 822 | return true; |
| 823 | } |
| 824 | |
| 825 | /* The main function of the pass scans statements for switches and invokes |
| 826 | process_switch on them. */ |
| 827 | |
| 828 | static unsigned int |
| 829 | do_switchconv (void) |
| 830 | { |
| 831 | basic_block bb; |
| 832 | |
| 833 | FOR_EACH_BB (bb) |
| 834 | { |
| 835 | gimple stmt = last_stmt (bb); |
| 836 | if (stmt && gimple_code (stmt) == GIMPLE_SWITCH) |
| 837 | { |
| 838 | if (dump_file) |
| 839 | { |
| 840 | expanded_location loc = expand_location (gimple_location (stmt)); |
| 841 | |
| 842 | fprintf (dump_file, "beginning to process the following " |
| 843 | "SWITCH statement (%s:%d) : ------- \n", |
| 844 | loc.file, loc.line); |
| 845 | print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM); |
| 846 | fprintf (dump_file, "\n"); |
| 847 | } |
| 848 | |
| 849 | info.reason = NULL; |
| 850 | if (process_switch (stmt)) |
| 851 | { |
| 852 | if (dump_file) |
| 853 | { |
| 854 | fprintf (dump_file, "Switch converted\n"); |
| 855 | fprintf (dump_file, "--------------------------------\n"); |
| 856 | } |
| 857 | } |
| 858 | else |
| 859 | { |
| 860 | if (dump_file) |
| 861 | { |
| 862 | gcc_assert (info.reason); |
| 863 | fprintf (dump_file, "Bailing out - "); |
| 864 | fprintf (dump_file, info.reason); |
| 865 | fprintf (dump_file, "--------------------------------\n"); |
| 866 | } |
| 867 | } |
| 868 | } |
| 869 | } |
| 870 | |
| 871 | return 0; |
| 872 | } |
| 873 | |
| 874 | /* The pass gate. */ |
| 875 | |
| 876 | static bool |
| 877 | switchconv_gate (void) |
| 878 | { |
| 879 | return flag_tree_switch_conversion != 0; |
| 880 | } |
| 881 | |
| 882 | struct gimple_opt_pass pass_convert_switch = |
| 883 | { |
| 884 | { |
| 885 | GIMPLE_PASS, |
| 886 | "switchconv", /* name */ |
| 887 | switchconv_gate, /* gate */ |
| 888 | do_switchconv, /* execute */ |
| 889 | NULL, /* sub */ |
| 890 | NULL, /* next */ |
| 891 | 0, /* static_pass_number */ |
| 892 | TV_TREE_SWITCH_CONVERSION, /* tv_id */ |
| 893 | PROP_cfg | PROP_ssa, /* properties_required */ |
| 894 | 0, /* properties_provided */ |
| 895 | 0, /* properties_destroyed */ |
| 896 | 0, /* todo_flags_start */ |
| 897 | TODO_update_ssa | TODO_dump_func |
| 898 | | TODO_ggc_collect | TODO_verify_ssa /* todo_flags_finish */ |
| 899 | } |
| 900 | }; |