Mercurial > hg > CbC > CbC_gcc
annotate gcc/tree-ssa-sink.c @ 144:8f4e72ab4e11
fix segmentation fault caused by nothing next cur_op to end
| author | Takahiro SHIMIZU <anatofuz@cr.ie.u-ryukyu.ac.jp> |
|---|---|
| date | Sun, 23 Dec 2018 21:23:56 +0900 |
| parents | 84e7813d76e9 |
| children | 1830386684a0 |
| rev | line source |
|---|---|
| 0 | 1 /* Code sinking for trees |
| 131 | 2 Copyright (C) 2001-2018 Free Software Foundation, Inc. |
| 0 | 3 Contributed by Daniel Berlin <dan@dberlin.org> |
| 4 | |
| 5 This file is part of GCC. | |
| 6 | |
| 7 GCC is free software; you can redistribute it and/or modify | |
| 8 it under the terms of the GNU General Public License as published by | |
| 9 the Free Software Foundation; either version 3, or (at your option) | |
| 10 any later version. | |
| 11 | |
| 12 GCC is distributed in the hope that it will be useful, | |
| 13 but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
| 15 GNU General Public License 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" | |
| 111 | 24 #include "backend.h" |
| 0 | 25 #include "tree.h" |
| 26 #include "gimple.h" | |
| 111 | 27 #include "cfghooks.h" |
| 0 | 28 #include "tree-pass.h" |
| 111 | 29 #include "ssa.h" |
| 30 #include "gimple-pretty-print.h" | |
| 31 #include "fold-const.h" | |
| 32 #include "stor-layout.h" | |
| 33 #include "cfganal.h" | |
| 34 #include "gimple-iterator.h" | |
| 35 #include "tree-cfg.h" | |
| 0 | 36 #include "cfgloop.h" |
| 111 | 37 #include "params.h" |
| 0 | 38 |
| 39 /* TODO: | |
| 40 1. Sinking store only using scalar promotion (IE without moving the RHS): | |
| 41 | |
| 42 *q = p; | |
| 43 p = p + 1; | |
| 44 if (something) | |
| 45 *q = <not p>; | |
| 46 else | |
| 47 y = *q; | |
| 48 | |
|
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49 |
| 0 | 50 should become |
| 51 sinktemp = p; | |
| 52 p = p + 1; | |
| 53 if (something) | |
| 54 *q = <not p>; | |
| 55 else | |
| 56 { | |
| 57 *q = sinktemp; | |
| 58 y = *q | |
| 59 } | |
| 60 Store copy propagation will take care of the store elimination above. | |
|
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61 |
| 0 | 62 |
| 63 2. Sinking using Partial Dead Code Elimination. */ | |
| 64 | |
| 65 | |
| 66 static struct | |
|
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67 { |
| 0 | 68 /* The number of statements sunk down the flowgraph by code sinking. */ |
| 69 int sunk; | |
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70 |
| 0 | 71 } sink_stats; |
| 72 | |
| 73 | |
| 74 /* Given a PHI, and one of its arguments (DEF), find the edge for | |
| 75 that argument and return it. If the argument occurs twice in the PHI node, | |
| 76 we return NULL. */ | |
| 77 | |
| 78 static basic_block | |
| 111 | 79 find_bb_for_arg (gphi *phi, tree def) |
| 0 | 80 { |
| 81 size_t i; | |
| 82 bool foundone = false; | |
| 83 basic_block result = NULL; | |
| 84 for (i = 0; i < gimple_phi_num_args (phi); i++) | |
| 85 if (PHI_ARG_DEF (phi, i) == def) | |
| 86 { | |
| 87 if (foundone) | |
| 88 return NULL; | |
| 89 foundone = true; | |
| 90 result = gimple_phi_arg_edge (phi, i)->src; | |
| 91 } | |
| 92 return result; | |
| 93 } | |
| 94 | |
| 95 /* When the first immediate use is in a statement, then return true if all | |
| 96 immediate uses in IMM are in the same statement. | |
| 97 We could also do the case where the first immediate use is in a phi node, | |
| 98 and all the other uses are in phis in the same basic block, but this | |
| 99 requires some expensive checking later (you have to make sure no def/vdef | |
| 100 in the statement occurs for multiple edges in the various phi nodes it's | |
| 101 used in, so that you only have one place you can sink it to. */ | |
| 102 | |
| 103 static bool | |
| 111 | 104 all_immediate_uses_same_place (def_operand_p def_p) |
| 0 | 105 { |
| 111 | 106 tree var = DEF_FROM_PTR (def_p); |
| 0 | 107 imm_use_iterator imm_iter; |
| 108 use_operand_p use_p; | |
| 109 | |
| 111 | 110 gimple *firstuse = NULL; |
| 111 FOR_EACH_IMM_USE_FAST (use_p, imm_iter, var) | |
| 0 | 112 { |
| 111 | 113 if (is_gimple_debug (USE_STMT (use_p))) |
| 114 continue; | |
| 115 if (firstuse == NULL) | |
| 116 firstuse = USE_STMT (use_p); | |
| 117 else | |
| 118 if (firstuse != USE_STMT (use_p)) | |
| 119 return false; | |
| 0 | 120 } |
| 121 | |
| 122 return true; | |
| 123 } | |
| 124 | |
| 125 /* Find the nearest common dominator of all of the immediate uses in IMM. */ | |
| 126 | |
| 127 static basic_block | |
| 111 | 128 nearest_common_dominator_of_uses (def_operand_p def_p, bool *debug_stmts) |
|
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129 { |
| 111 | 130 tree var = DEF_FROM_PTR (def_p); |
| 131 auto_bitmap blocks; | |
| 0 | 132 basic_block commondom; |
| 133 unsigned int j; | |
| 134 bitmap_iterator bi; | |
| 135 imm_use_iterator imm_iter; | |
| 136 use_operand_p use_p; | |
| 137 | |
| 111 | 138 FOR_EACH_IMM_USE_FAST (use_p, imm_iter, var) |
| 0 | 139 { |
| 111 | 140 gimple *usestmt = USE_STMT (use_p); |
| 141 basic_block useblock; | |
| 0 | 142 |
| 111 | 143 if (gphi *phi = dyn_cast <gphi *> (usestmt)) |
| 144 { | |
| 145 int idx = PHI_ARG_INDEX_FROM_USE (use_p); | |
| 0 | 146 |
| 111 | 147 useblock = gimple_phi_arg_edge (phi, idx)->src; |
| 148 } | |
| 149 else if (is_gimple_debug (usestmt)) | |
| 150 { | |
| 151 *debug_stmts = true; | |
| 152 continue; | |
| 153 } | |
| 154 else | |
| 155 { | |
| 156 useblock = gimple_bb (usestmt); | |
| 157 } | |
| 0 | 158 |
| 111 | 159 /* Short circuit. Nothing dominates the entry block. */ |
| 160 if (useblock == ENTRY_BLOCK_PTR_FOR_FN (cfun)) | |
| 161 return NULL; | |
| 162 | |
| 163 bitmap_set_bit (blocks, useblock->index); | |
| 0 | 164 } |
| 111 | 165 commondom = BASIC_BLOCK_FOR_FN (cfun, bitmap_first_set_bit (blocks)); |
| 0 | 166 EXECUTE_IF_SET_IN_BITMAP (blocks, 0, j, bi) |
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167 commondom = nearest_common_dominator (CDI_DOMINATORS, commondom, |
| 111 | 168 BASIC_BLOCK_FOR_FN (cfun, j)); |
| 0 | 169 return commondom; |
| 170 } | |
| 171 | |
| 111 | 172 /* Given EARLY_BB and LATE_BB, two blocks in a path through the dominator |
| 173 tree, return the best basic block between them (inclusive) to place | |
| 174 statements. | |
| 175 | |
| 176 We want the most control dependent block in the shallowest loop nest. | |
| 177 | |
| 178 If the resulting block is in a shallower loop nest, then use it. Else | |
| 179 only use the resulting block if it has significantly lower execution | |
| 180 frequency than EARLY_BB to avoid gratutious statement movement. We | |
| 181 consider statements with VOPS more desirable to move. | |
| 182 | |
| 183 This pass would obviously benefit from PDO as it utilizes block | |
| 184 frequencies. It would also benefit from recomputing frequencies | |
| 185 if profile data is not available since frequencies often get out | |
| 186 of sync with reality. */ | |
| 187 | |
| 188 static basic_block | |
| 189 select_best_block (basic_block early_bb, | |
| 190 basic_block late_bb, | |
| 191 gimple *stmt) | |
| 192 { | |
| 193 basic_block best_bb = late_bb; | |
| 194 basic_block temp_bb = late_bb; | |
| 195 int threshold; | |
| 196 | |
| 197 while (temp_bb != early_bb) | |
| 198 { | |
| 199 /* If we've moved into a lower loop nest, then that becomes | |
| 200 our best block. */ | |
| 201 if (bb_loop_depth (temp_bb) < bb_loop_depth (best_bb)) | |
| 202 best_bb = temp_bb; | |
| 203 | |
| 204 /* Walk up the dominator tree, hopefully we'll find a shallower | |
| 205 loop nest. */ | |
| 206 temp_bb = get_immediate_dominator (CDI_DOMINATORS, temp_bb); | |
| 207 } | |
| 208 | |
| 209 /* If we found a shallower loop nest, then we always consider that | |
| 210 a win. This will always give us the most control dependent block | |
| 211 within that loop nest. */ | |
| 212 if (bb_loop_depth (best_bb) < bb_loop_depth (early_bb)) | |
| 213 return best_bb; | |
| 214 | |
| 215 /* Get the sinking threshold. If the statement to be moved has memory | |
| 216 operands, then increase the threshold by 7% as those are even more | |
| 217 profitable to avoid, clamping at 100%. */ | |
| 218 threshold = PARAM_VALUE (PARAM_SINK_FREQUENCY_THRESHOLD); | |
| 219 if (gimple_vuse (stmt) || gimple_vdef (stmt)) | |
| 220 { | |
| 221 threshold += 7; | |
| 222 if (threshold > 100) | |
| 223 threshold = 100; | |
| 224 } | |
| 225 | |
| 226 /* If BEST_BB is at the same nesting level, then require it to have | |
| 227 significantly lower execution frequency to avoid gratutious movement. */ | |
| 228 if (bb_loop_depth (best_bb) == bb_loop_depth (early_bb) | |
| 131 | 229 /* If result of comparsion is unknown, preffer EARLY_BB. |
| 230 Thus use !(...>=..) rather than (...<...) */ | |
| 231 && !(best_bb->count.apply_scale (100, 1) | |
| 232 > (early_bb->count.apply_scale (threshold, 1)))) | |
| 111 | 233 return best_bb; |
| 234 | |
| 235 /* No better block found, so return EARLY_BB, which happens to be the | |
| 236 statement's original block. */ | |
| 237 return early_bb; | |
| 238 } | |
| 239 | |
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240 /* Given a statement (STMT) and the basic block it is currently in (FROMBB), |
| 0 | 241 determine the location to sink the statement to, if any. |
| 242 Returns true if there is such location; in that case, TOGSI points to the | |
| 243 statement before that STMT should be moved. */ | |
| 244 | |
| 245 static bool | |
| 111 | 246 statement_sink_location (gimple *stmt, basic_block frombb, |
| 247 gimple_stmt_iterator *togsi, bool *zero_uses_p) | |
| 0 | 248 { |
| 111 | 249 gimple *use; |
| 0 | 250 use_operand_p one_use = NULL_USE_OPERAND_P; |
| 251 basic_block sinkbb; | |
| 252 use_operand_p use_p; | |
| 253 def_operand_p def_p; | |
| 254 ssa_op_iter iter; | |
| 255 imm_use_iterator imm_iter; | |
| 256 | |
| 111 | 257 *zero_uses_p = false; |
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258 |
| 111 | 259 /* We only can sink assignments and non-looping const/pure calls. */ |
| 260 int cf; | |
| 261 if (!is_gimple_assign (stmt) | |
| 262 && (!is_gimple_call (stmt) | |
| 263 || !((cf = gimple_call_flags (stmt)) & (ECF_CONST|ECF_PURE)) | |
| 264 || (cf & ECF_LOOPING_CONST_OR_PURE))) | |
| 0 | 265 return false; |
| 266 | |
| 111 | 267 /* We only can sink stmts with a single definition. */ |
| 268 def_p = single_ssa_def_operand (stmt, SSA_OP_ALL_DEFS); | |
| 269 if (def_p == NULL_DEF_OPERAND_P) | |
| 0 | 270 return false; |
| 271 | |
| 272 /* There are a few classes of things we can't or don't move, some because we | |
| 273 don't have code to handle it, some because it's not profitable and some | |
|
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274 because it's not legal. |
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275 |
| 0 | 276 We can't sink things that may be global stores, at least not without |
| 277 calculating a lot more information, because we may cause it to no longer | |
| 278 be seen by an external routine that needs it depending on where it gets | |
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279 moved to. |
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280 |
| 0 | 281 We can't sink statements that end basic blocks without splitting the |
| 282 incoming edge for the sink location to place it there. | |
| 283 | |
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284 We can't sink statements that have volatile operands. |
| 0 | 285 |
| 286 We don't want to sink dead code, so anything with 0 immediate uses is not | |
| 287 sunk. | |
| 288 | |
| 289 Don't sink BLKmode assignments if current function has any local explicit | |
| 290 register variables, as BLKmode assignments may involve memcpy or memset | |
| 291 calls or, on some targets, inline expansion thereof that sometimes need | |
| 292 to use specific hard registers. | |
| 293 | |
| 294 */ | |
| 295 if (stmt_ends_bb_p (stmt) | |
| 296 || gimple_has_side_effects (stmt) | |
| 297 || (cfun->has_local_explicit_reg_vars | |
| 111 | 298 && TYPE_MODE (TREE_TYPE (gimple_get_lhs (stmt))) == BLKmode)) |
| 0 | 299 return false; |
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300 |
| 111 | 301 /* Return if there are no immediate uses of this stmt. */ |
| 302 if (has_zero_uses (DEF_FROM_PTR (def_p))) | |
| 0 | 303 { |
| 111 | 304 *zero_uses_p = true; |
| 305 return false; | |
| 0 | 306 } |
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307 |
| 111 | 308 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (DEF_FROM_PTR (def_p))) |
| 309 return false; | |
| 310 | |
| 0 | 311 FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_ALL_USES) |
| 312 { | |
| 313 tree use = USE_FROM_PTR (use_p); | |
| 314 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (use)) | |
| 315 return false; | |
| 316 } | |
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317 |
| 111 | 318 use = NULL; |
| 319 | |
| 320 /* If stmt is a store the one and only use needs to be the VOP | |
| 321 merging PHI node. */ | |
| 322 if (virtual_operand_p (DEF_FROM_PTR (def_p))) | |
| 323 { | |
| 324 FOR_EACH_IMM_USE_FAST (use_p, imm_iter, DEF_FROM_PTR (def_p)) | |
| 325 { | |
| 326 gimple *use_stmt = USE_STMT (use_p); | |
| 327 | |
| 328 /* A killing definition is not a use. */ | |
| 329 if ((gimple_has_lhs (use_stmt) | |
| 330 && operand_equal_p (gimple_get_lhs (stmt), | |
| 331 gimple_get_lhs (use_stmt), 0)) | |
| 332 || stmt_kills_ref_p (use_stmt, gimple_get_lhs (stmt))) | |
| 333 { | |
| 334 /* If use_stmt is or might be a nop assignment then USE_STMT | |
| 335 acts as a use as well as definition. */ | |
| 336 if (stmt != use_stmt | |
| 337 && ref_maybe_used_by_stmt_p (use_stmt, | |
| 338 gimple_get_lhs (stmt))) | |
| 339 return false; | |
| 340 continue; | |
| 341 } | |
| 342 | |
| 343 if (gimple_code (use_stmt) != GIMPLE_PHI) | |
| 344 return false; | |
| 345 | |
| 346 if (use | |
| 347 && use != use_stmt) | |
| 348 return false; | |
| 349 | |
| 350 use = use_stmt; | |
| 351 } | |
| 352 if (!use) | |
| 353 return false; | |
| 354 } | |
| 0 | 355 /* If all the immediate uses are not in the same place, find the nearest |
| 356 common dominator of all the immediate uses. For PHI nodes, we have to | |
| 357 find the nearest common dominator of all of the predecessor blocks, since | |
| 358 that is where insertion would have to take place. */ | |
| 111 | 359 else if (gimple_vuse (stmt) |
| 360 || !all_immediate_uses_same_place (def_p)) | |
| 0 | 361 { |
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362 bool debug_stmts = false; |
| 111 | 363 basic_block commondom = nearest_common_dominator_of_uses (def_p, |
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364 &debug_stmts); |
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365 |
| 0 | 366 if (commondom == frombb) |
| 367 return false; | |
| 368 | |
| 111 | 369 /* If this is a load then do not sink past any stores. |
| 370 ??? This is overly simple but cheap. We basically look | |
| 371 for an existing load with the same VUSE in the path to one | |
| 372 of the sink candidate blocks and we adjust commondom to the | |
| 373 nearest to commondom. */ | |
| 374 if (gimple_vuse (stmt)) | |
| 375 { | |
| 376 /* Do not sink loads from hard registers. */ | |
| 377 if (gimple_assign_single_p (stmt) | |
| 378 && TREE_CODE (gimple_assign_rhs1 (stmt)) == VAR_DECL | |
| 379 && DECL_HARD_REGISTER (gimple_assign_rhs1 (stmt))) | |
| 380 return false; | |
| 381 | |
| 382 imm_use_iterator imm_iter; | |
| 383 use_operand_p use_p; | |
| 384 basic_block found = NULL; | |
| 385 FOR_EACH_IMM_USE_FAST (use_p, imm_iter, gimple_vuse (stmt)) | |
| 386 { | |
| 387 gimple *use_stmt = USE_STMT (use_p); | |
| 388 basic_block bb = gimple_bb (use_stmt); | |
| 389 /* For PHI nodes the block we know sth about | |
| 390 is the incoming block with the use. */ | |
| 391 if (gimple_code (use_stmt) == GIMPLE_PHI) | |
| 392 bb = EDGE_PRED (bb, PHI_ARG_INDEX_FROM_USE (use_p))->src; | |
| 393 /* Any dominator of commondom would be ok with | |
| 394 adjusting commondom to that block. */ | |
| 395 bb = nearest_common_dominator (CDI_DOMINATORS, bb, commondom); | |
| 396 if (!found) | |
| 397 found = bb; | |
| 398 else if (dominated_by_p (CDI_DOMINATORS, bb, found)) | |
| 399 found = bb; | |
| 400 /* If we can't improve, stop. */ | |
| 401 if (found == commondom) | |
| 402 break; | |
| 403 } | |
| 404 commondom = found; | |
| 405 if (commondom == frombb) | |
| 406 return false; | |
| 407 } | |
| 408 | |
| 0 | 409 /* Our common dominator has to be dominated by frombb in order to be a |
| 410 trivially safe place to put this statement, since it has multiple | |
|
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411 uses. */ |
| 0 | 412 if (!dominated_by_p (CDI_DOMINATORS, commondom, frombb)) |
| 413 return false; | |
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414 |
| 111 | 415 commondom = select_best_block (frombb, commondom, stmt); |
| 0 | 416 |
| 111 | 417 if (commondom == frombb) |
| 418 return false; | |
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419 |
| 0 | 420 *togsi = gsi_after_labels (commondom); |
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421 |
| 0 | 422 return true; |
| 423 } | |
| 111 | 424 else |
| 0 | 425 { |
| 111 | 426 FOR_EACH_IMM_USE_FAST (one_use, imm_iter, DEF_FROM_PTR (def_p)) |
| 427 { | |
| 428 if (is_gimple_debug (USE_STMT (one_use))) | |
| 429 continue; | |
| 430 break; | |
| 431 } | |
| 432 use = USE_STMT (one_use); | |
| 0 | 433 |
| 111 | 434 if (gimple_code (use) != GIMPLE_PHI) |
| 435 { | |
| 436 sinkbb = gimple_bb (use); | |
| 437 sinkbb = select_best_block (frombb, gimple_bb (use), stmt); | |
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438 |
| 111 | 439 if (sinkbb == frombb) |
| 440 return false; | |
|
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441 |
| 111 | 442 *togsi = gsi_for_stmt (use); |
| 443 | |
| 444 return true; | |
| 445 } | |
| 0 | 446 } |
| 447 | |
| 111 | 448 sinkbb = find_bb_for_arg (as_a <gphi *> (use), DEF_FROM_PTR (def_p)); |
| 0 | 449 |
| 111 | 450 /* This can happen if there are multiple uses in a PHI. */ |
| 0 | 451 if (!sinkbb) |
| 452 return false; | |
| 111 | 453 |
| 454 sinkbb = select_best_block (frombb, sinkbb, stmt); | |
| 455 if (!sinkbb || sinkbb == frombb) | |
| 0 | 456 return false; |
| 457 | |
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458 /* If the latch block is empty, don't make it non-empty by sinking |
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459 something into it. */ |
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460 if (sinkbb == frombb->loop_father->latch |
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461 && empty_block_p (sinkbb)) |
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462 return false; |
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463 |
| 0 | 464 *togsi = gsi_after_labels (sinkbb); |
| 465 | |
| 466 return true; | |
| 467 } | |
| 468 | |
| 469 /* Perform code sinking on BB */ | |
| 470 | |
| 471 static void | |
| 472 sink_code_in_bb (basic_block bb) | |
| 473 { | |
| 474 basic_block son; | |
| 475 gimple_stmt_iterator gsi; | |
| 476 edge_iterator ei; | |
| 477 edge e; | |
| 478 bool last = true; | |
|
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479 |
| 0 | 480 /* If this block doesn't dominate anything, there can't be any place to sink |
| 481 the statements to. */ | |
| 482 if (first_dom_son (CDI_DOMINATORS, bb) == NULL) | |
| 483 goto earlyout; | |
| 484 | |
| 485 /* We can't move things across abnormal edges, so don't try. */ | |
| 486 FOR_EACH_EDGE (e, ei, bb->succs) | |
| 487 if (e->flags & EDGE_ABNORMAL) | |
| 488 goto earlyout; | |
| 489 | |
| 490 for (gsi = gsi_last_bb (bb); !gsi_end_p (gsi);) | |
| 491 { | |
| 111 | 492 gimple *stmt = gsi_stmt (gsi); |
| 0 | 493 gimple_stmt_iterator togsi; |
| 111 | 494 bool zero_uses_p; |
| 0 | 495 |
| 111 | 496 if (!statement_sink_location (stmt, bb, &togsi, &zero_uses_p)) |
| 0 | 497 { |
| 111 | 498 gimple_stmt_iterator saved = gsi; |
| 0 | 499 if (!gsi_end_p (gsi)) |
| 500 gsi_prev (&gsi); | |
| 111 | 501 /* If we face a dead stmt remove it as it possibly blocks |
| 502 sinking of uses. */ | |
| 503 if (zero_uses_p | |
| 504 && ! gimple_vdef (stmt)) | |
| 505 { | |
| 506 gsi_remove (&saved, true); | |
| 507 release_defs (stmt); | |
| 508 } | |
| 509 else | |
| 510 last = false; | |
| 0 | 511 continue; |
|
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512 } |
| 0 | 513 if (dump_file) |
| 514 { | |
| 515 fprintf (dump_file, "Sinking "); | |
| 516 print_gimple_stmt (dump_file, stmt, 0, TDF_VOPS); | |
| 517 fprintf (dump_file, " from bb %d to bb %d\n", | |
| 518 bb->index, (gsi_bb (togsi))->index); | |
| 519 } | |
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520 |
| 111 | 521 /* Update virtual operands of statements in the path we |
| 522 do not sink to. */ | |
| 523 if (gimple_vdef (stmt)) | |
| 524 { | |
| 525 imm_use_iterator iter; | |
| 526 use_operand_p use_p; | |
| 527 gimple *vuse_stmt; | |
| 528 | |
| 529 FOR_EACH_IMM_USE_STMT (vuse_stmt, iter, gimple_vdef (stmt)) | |
| 530 if (gimple_code (vuse_stmt) != GIMPLE_PHI) | |
| 531 FOR_EACH_IMM_USE_ON_STMT (use_p, iter) | |
| 532 SET_USE (use_p, gimple_vuse (stmt)); | |
| 533 } | |
| 534 | |
| 0 | 535 /* If this is the end of the basic block, we need to insert at the end |
| 536 of the basic block. */ | |
| 537 if (gsi_end_p (togsi)) | |
| 538 gsi_move_to_bb_end (&gsi, gsi_bb (togsi)); | |
| 539 else | |
| 540 gsi_move_before (&gsi, &togsi); | |
| 541 | |
| 542 sink_stats.sunk++; | |
| 543 | |
| 544 /* If we've just removed the last statement of the BB, the | |
| 545 gsi_end_p() test below would fail, but gsi_prev() would have | |
| 546 succeeded, and we want it to succeed. So we keep track of | |
| 547 whether we're at the last statement and pick up the new last | |
| 548 statement. */ | |
| 549 if (last) | |
| 550 { | |
| 551 gsi = gsi_last_bb (bb); | |
| 552 continue; | |
| 553 } | |
| 554 | |
| 555 last = false; | |
| 556 if (!gsi_end_p (gsi)) | |
| 557 gsi_prev (&gsi); | |
|
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558 |
| 0 | 559 } |
| 560 earlyout: | |
| 561 for (son = first_dom_son (CDI_POST_DOMINATORS, bb); | |
| 562 son; | |
| 563 son = next_dom_son (CDI_POST_DOMINATORS, son)) | |
| 564 { | |
| 565 sink_code_in_bb (son); | |
| 566 } | |
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567 } |
| 0 | 568 |
| 569 /* Perform code sinking. | |
| 570 This moves code down the flowgraph when we know it would be | |
| 571 profitable to do so, or it wouldn't increase the number of | |
| 572 executions of the statement. | |
| 573 | |
| 574 IE given | |
|
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575 |
| 0 | 576 a_1 = b + c; |
| 577 if (<something>) | |
| 578 { | |
| 579 } | |
| 580 else | |
| 581 { | |
| 582 foo (&b, &c); | |
| 583 a_5 = b + c; | |
| 584 } | |
| 585 a_6 = PHI (a_5, a_1); | |
| 586 USE a_6. | |
| 587 | |
| 588 we'll transform this into: | |
| 589 | |
| 590 if (<something>) | |
| 591 { | |
| 592 a_1 = b + c; | |
| 593 } | |
| 594 else | |
| 595 { | |
| 596 foo (&b, &c); | |
| 597 a_5 = b + c; | |
| 598 } | |
| 599 a_6 = PHI (a_5, a_1); | |
| 600 USE a_6. | |
| 601 | |
| 602 Note that this reduces the number of computations of a = b + c to 1 | |
| 603 when we take the else edge, instead of 2. | |
| 604 */ | |
| 111 | 605 namespace { |
| 606 | |
| 607 const pass_data pass_data_sink_code = | |
| 608 { | |
| 609 GIMPLE_PASS, /* type */ | |
| 610 "sink", /* name */ | |
| 611 OPTGROUP_NONE, /* optinfo_flags */ | |
| 612 TV_TREE_SINK, /* tv_id */ | |
| 613 /* PROP_no_crit_edges is ensured by running split_critical_edges in | |
| 614 pass_data_sink_code::execute (). */ | |
| 615 ( PROP_cfg | PROP_ssa ), /* properties_required */ | |
| 616 0, /* properties_provided */ | |
| 617 0, /* properties_destroyed */ | |
| 618 0, /* todo_flags_start */ | |
| 619 TODO_update_ssa, /* todo_flags_finish */ | |
| 620 }; | |
| 621 | |
| 622 class pass_sink_code : public gimple_opt_pass | |
| 623 { | |
| 624 public: | |
| 625 pass_sink_code (gcc::context *ctxt) | |
| 626 : gimple_opt_pass (pass_data_sink_code, ctxt) | |
| 627 {} | |
| 628 | |
| 629 /* opt_pass methods: */ | |
| 630 virtual bool gate (function *) { return flag_tree_sink != 0; } | |
| 631 virtual unsigned int execute (function *); | |
| 632 | |
| 633 }; // class pass_sink_code | |
| 634 | |
| 635 unsigned int | |
| 636 pass_sink_code::execute (function *fun) | |
| 0 | 637 { |
| 638 loop_optimizer_init (LOOPS_NORMAL); | |
| 111 | 639 split_critical_edges (); |
| 0 | 640 connect_infinite_loops_to_exit (); |
| 641 memset (&sink_stats, 0, sizeof (sink_stats)); | |
| 642 calculate_dominance_info (CDI_DOMINATORS); | |
| 643 calculate_dominance_info (CDI_POST_DOMINATORS); | |
| 111 | 644 sink_code_in_bb (EXIT_BLOCK_PTR_FOR_FN (fun)); |
| 645 statistics_counter_event (fun, "Sunk statements", sink_stats.sunk); | |
| 0 | 646 free_dominance_info (CDI_POST_DOMINATORS); |
| 647 remove_fake_exit_edges (); | |
| 648 loop_optimizer_finalize (); | |
| 649 | |
| 650 return 0; | |
| 651 } | |
| 652 | |
| 111 | 653 } // anon namespace |
| 0 | 654 |
| 111 | 655 gimple_opt_pass * |
| 656 make_pass_sink_code (gcc::context *ctxt) | |
| 0 | 657 { |
| 111 | 658 return new pass_sink_code (ctxt); |
| 659 } |