Mercurial > hg > CbC > CbC_gcc
annotate gcc/tree-cfgcleanup.c @ 138:fc828634a951
merge
| author | Shinji KONO <kono@ie.u-ryukyu.ac.jp> |
|---|---|
| date | Thu, 08 Nov 2018 14:17:14 +0900 |
| parents | 84e7813d76e9 |
| children | 1830386684a0 |
| rev | line source |
|---|---|
| 0 | 1 /* CFG cleanup for trees. |
| 131 | 2 Copyright (C) 2001-2018 Free Software Foundation, Inc. |
| 0 | 3 |
| 4 This file is part of GCC. | |
| 5 | |
| 6 GCC is free software; you can redistribute it and/or modify | |
| 7 it under the terms of the GNU General Public License as published by | |
| 8 the Free Software Foundation; either version 3, or (at your option) | |
| 9 any later version. | |
| 10 | |
| 11 GCC is distributed in the hope that it will be useful, | |
| 12 but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
| 14 GNU General Public License 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" | |
| 111 | 23 #include "backend.h" |
| 24 #include "rtl.h" | |
| 0 | 25 #include "tree.h" |
| 111 | 26 #include "gimple.h" |
| 27 #include "cfghooks.h" | |
| 28 #include "tree-pass.h" | |
| 29 #include "ssa.h" | |
|
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30 #include "diagnostic-core.h" |
| 111 | 31 #include "fold-const.h" |
| 32 #include "cfganal.h" | |
| 33 #include "cfgcleanup.h" | |
| 34 #include "tree-eh.h" | |
| 35 #include "gimplify.h" | |
| 36 #include "gimple-iterator.h" | |
| 37 #include "tree-cfg.h" | |
| 38 #include "tree-ssa-loop-manip.h" | |
| 39 #include "tree-dfa.h" | |
| 40 #include "tree-ssa.h" | |
| 0 | 41 #include "cfgloop.h" |
| 42 #include "tree-scalar-evolution.h" | |
| 111 | 43 #include "gimple-match.h" |
| 44 #include "gimple-fold.h" | |
| 45 #include "tree-ssa-loop-niter.h" | |
| 46 | |
| 0 | 47 |
| 48 /* The set of blocks in that at least one of the following changes happened: | |
| 49 -- the statement at the end of the block was changed | |
| 50 -- the block was newly created | |
| 51 -- the set of the predecessors of the block changed | |
| 52 -- the set of the successors of the block changed | |
| 53 ??? Maybe we could track these changes separately, since they determine | |
| 54 what cleanups it makes sense to try on the block. */ | |
| 55 bitmap cfgcleanup_altered_bbs; | |
| 56 | |
| 57 /* Remove any fallthru edge from EV. Return true if an edge was removed. */ | |
| 58 | |
| 59 static bool | |
| 111 | 60 remove_fallthru_edge (vec<edge, va_gc> *ev) |
| 0 | 61 { |
| 62 edge_iterator ei; | |
| 63 edge e; | |
| 64 | |
| 65 FOR_EACH_EDGE (e, ei, ev) | |
| 66 if ((e->flags & EDGE_FALLTHRU) != 0) | |
| 67 { | |
| 111 | 68 if (e->flags & EDGE_COMPLEX) |
| 69 e->flags &= ~EDGE_FALLTHRU; | |
| 70 else | |
| 71 remove_edge_and_dominated_blocks (e); | |
| 0 | 72 return true; |
| 73 } | |
| 74 return false; | |
| 75 } | |
| 76 | |
| 111 | 77 /* Convert a SWTCH with single non-default case to gcond and replace it |
| 78 at GSI. */ | |
| 79 | |
| 80 static bool | |
| 81 convert_single_case_switch (gswitch *swtch, gimple_stmt_iterator &gsi) | |
| 82 { | |
| 83 if (gimple_switch_num_labels (swtch) != 2) | |
| 84 return false; | |
| 85 | |
| 86 tree index = gimple_switch_index (swtch); | |
| 87 tree label = gimple_switch_label (swtch, 1); | |
| 88 tree low = CASE_LOW (label); | |
| 89 tree high = CASE_HIGH (label); | |
| 90 | |
| 131 | 91 basic_block default_bb = gimple_switch_default_bb (cfun, swtch); |
| 92 basic_block case_bb = label_to_block (cfun, CASE_LABEL (label)); | |
| 111 | 93 |
| 94 basic_block bb = gimple_bb (swtch); | |
| 95 gcond *cond; | |
| 96 | |
| 97 /* Replace switch statement with condition statement. */ | |
| 98 if (high) | |
| 99 { | |
| 100 tree lhs, rhs; | |
| 101 generate_range_test (bb, index, low, high, &lhs, &rhs); | |
| 102 cond = gimple_build_cond (LE_EXPR, lhs, rhs, NULL_TREE, NULL_TREE); | |
| 103 } | |
| 104 else | |
| 105 cond = gimple_build_cond (EQ_EXPR, index, | |
| 106 fold_convert (TREE_TYPE (index), low), | |
| 107 NULL_TREE, NULL_TREE); | |
| 108 | |
| 109 gsi_replace (&gsi, cond, true); | |
| 110 | |
| 111 /* Update edges. */ | |
| 112 edge case_edge = find_edge (bb, case_bb); | |
| 113 edge default_edge = find_edge (bb, default_bb); | |
| 114 | |
| 115 case_edge->flags |= EDGE_TRUE_VALUE; | |
| 116 default_edge->flags |= EDGE_FALSE_VALUE; | |
| 117 return true; | |
| 118 } | |
| 0 | 119 |
| 120 /* Disconnect an unreachable block in the control expression starting | |
| 121 at block BB. */ | |
| 122 | |
| 123 static bool | |
| 131 | 124 cleanup_control_expr_graph (basic_block bb, gimple_stmt_iterator gsi) |
| 0 | 125 { |
| 126 edge taken_edge; | |
| 127 bool retval = false; | |
| 111 | 128 gimple *stmt = gsi_stmt (gsi); |
| 0 | 129 |
| 130 if (!single_succ_p (bb)) | |
| 131 { | |
| 132 edge e; | |
| 133 edge_iterator ei; | |
| 134 bool warned; | |
| 111 | 135 tree val = NULL_TREE; |
| 136 | |
| 137 /* Try to convert a switch with just a single non-default case to | |
| 138 GIMPLE condition. */ | |
| 139 if (gimple_code (stmt) == GIMPLE_SWITCH | |
| 140 && convert_single_case_switch (as_a<gswitch *> (stmt), gsi)) | |
| 141 stmt = gsi_stmt (gsi); | |
| 0 | 142 |
| 143 fold_defer_overflow_warnings (); | |
|
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144 switch (gimple_code (stmt)) |
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145 { |
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146 case GIMPLE_COND: |
| 131 | 147 { |
| 148 gimple_match_op res_op; | |
| 149 if (gimple_simplify (stmt, &res_op, NULL, no_follow_ssa_edges, | |
| 150 no_follow_ssa_edges) | |
| 151 && res_op.code == INTEGER_CST) | |
| 152 val = res_op.ops[0]; | |
| 153 } | |
| 111 | 154 break; |
|
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155 |
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156 case GIMPLE_SWITCH: |
| 111 | 157 val = gimple_switch_index (as_a <gswitch *> (stmt)); |
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158 break; |
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159 |
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160 default: |
| 111 | 161 ; |
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162 } |
| 0 | 163 taken_edge = find_taken_edge (bb, val); |
| 164 if (!taken_edge) | |
| 165 { | |
| 166 fold_undefer_and_ignore_overflow_warnings (); | |
| 167 return false; | |
| 168 } | |
| 169 | |
| 170 /* Remove all the edges except the one that is always executed. */ | |
| 171 warned = false; | |
| 172 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); ) | |
| 173 { | |
| 174 if (e != taken_edge) | |
| 175 { | |
| 176 if (!warned) | |
| 177 { | |
| 178 fold_undefer_overflow_warnings | |
| 179 (true, stmt, WARN_STRICT_OVERFLOW_CONDITIONAL); | |
| 180 warned = true; | |
| 181 } | |
| 182 | |
| 183 taken_edge->probability += e->probability; | |
| 184 remove_edge_and_dominated_blocks (e); | |
| 185 retval = true; | |
| 186 } | |
| 187 else | |
| 188 ei_next (&ei); | |
| 189 } | |
| 190 if (!warned) | |
| 191 fold_undefer_and_ignore_overflow_warnings (); | |
| 192 } | |
| 193 else | |
| 194 taken_edge = single_succ_edge (bb); | |
| 195 | |
| 196 bitmap_set_bit (cfgcleanup_altered_bbs, bb->index); | |
| 197 gsi_remove (&gsi, true); | |
| 198 taken_edge->flags = EDGE_FALLTHRU; | |
| 199 | |
| 200 return retval; | |
| 201 } | |
| 202 | |
| 111 | 203 /* Cleanup the GF_CALL_CTRL_ALTERING flag according to |
| 204 to updated gimple_call_flags. */ | |
| 205 | |
| 206 static void | |
| 207 cleanup_call_ctrl_altering_flag (gimple *bb_end) | |
| 208 { | |
| 209 if (!is_gimple_call (bb_end) | |
| 210 || !gimple_call_ctrl_altering_p (bb_end)) | |
| 211 return; | |
| 212 | |
| 213 int flags = gimple_call_flags (bb_end); | |
| 214 if (((flags & (ECF_CONST | ECF_PURE)) | |
| 215 && !(flags & ECF_LOOPING_CONST_OR_PURE)) | |
| 216 || (flags & ECF_LEAF)) | |
| 217 gimple_call_set_ctrl_altering (bb_end, false); | |
| 218 } | |
| 219 | |
| 0 | 220 /* Try to remove superfluous control structures in basic block BB. Returns |
| 221 true if anything changes. */ | |
| 222 | |
| 223 static bool | |
| 131 | 224 cleanup_control_flow_bb (basic_block bb) |
| 0 | 225 { |
| 226 gimple_stmt_iterator gsi; | |
| 227 bool retval = false; | |
| 111 | 228 gimple *stmt; |
| 0 | 229 |
| 230 /* If the last statement of the block could throw and now cannot, | |
| 231 we need to prune cfg. */ | |
| 232 retval |= gimple_purge_dead_eh_edges (bb); | |
| 233 | |
| 111 | 234 gsi = gsi_last_nondebug_bb (bb); |
| 0 | 235 if (gsi_end_p (gsi)) |
| 236 return retval; | |
| 237 | |
| 238 stmt = gsi_stmt (gsi); | |
| 239 | |
| 111 | 240 /* Try to cleanup ctrl altering flag for call which ends bb. */ |
| 241 cleanup_call_ctrl_altering_flag (stmt); | |
| 242 | |
| 0 | 243 if (gimple_code (stmt) == GIMPLE_COND |
| 244 || gimple_code (stmt) == GIMPLE_SWITCH) | |
| 111 | 245 { |
| 246 gcc_checking_assert (gsi_stmt (gsi_last_bb (bb)) == stmt); | |
| 131 | 247 retval |= cleanup_control_expr_graph (bb, gsi); |
| 111 | 248 } |
| 0 | 249 else if (gimple_code (stmt) == GIMPLE_GOTO |
| 250 && TREE_CODE (gimple_goto_dest (stmt)) == ADDR_EXPR | |
| 251 && (TREE_CODE (TREE_OPERAND (gimple_goto_dest (stmt), 0)) | |
| 252 == LABEL_DECL)) | |
| 253 { | |
| 254 /* If we had a computed goto which has a compile-time determinable | |
| 255 destination, then we can eliminate the goto. */ | |
| 256 edge e; | |
| 257 tree label; | |
| 258 edge_iterator ei; | |
| 259 basic_block target_block; | |
| 260 | |
| 111 | 261 gcc_checking_assert (gsi_stmt (gsi_last_bb (bb)) == stmt); |
| 0 | 262 /* First look at all the outgoing edges. Delete any outgoing |
| 263 edges which do not go to the right block. For the one | |
| 264 edge which goes to the right block, fix up its flags. */ | |
| 265 label = TREE_OPERAND (gimple_goto_dest (stmt), 0); | |
| 111 | 266 if (DECL_CONTEXT (label) != cfun->decl) |
| 267 return retval; | |
| 131 | 268 target_block = label_to_block (cfun, label); |
| 0 | 269 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); ) |
| 270 { | |
| 271 if (e->dest != target_block) | |
| 272 remove_edge_and_dominated_blocks (e); | |
| 273 else | |
| 274 { | |
| 275 /* Turn off the EDGE_ABNORMAL flag. */ | |
| 276 e->flags &= ~EDGE_ABNORMAL; | |
| 277 | |
| 278 /* And set EDGE_FALLTHRU. */ | |
| 279 e->flags |= EDGE_FALLTHRU; | |
| 280 ei_next (&ei); | |
| 281 } | |
| 282 } | |
| 283 | |
| 284 bitmap_set_bit (cfgcleanup_altered_bbs, bb->index); | |
| 285 bitmap_set_bit (cfgcleanup_altered_bbs, target_block->index); | |
| 286 | |
| 287 /* Remove the GOTO_EXPR as it is not needed. The CFG has all the | |
| 288 relevant information we need. */ | |
| 289 gsi_remove (&gsi, true); | |
| 290 retval = true; | |
| 291 } | |
| 292 | |
| 293 /* Check for indirect calls that have been turned into | |
| 294 noreturn calls. */ | |
| 295 else if (is_gimple_call (stmt) | |
| 111 | 296 && gimple_call_noreturn_p (stmt)) |
| 297 { | |
| 298 /* If there are debug stmts after the noreturn call, remove them | |
| 299 now, they should be all unreachable anyway. */ | |
| 300 for (gsi_next (&gsi); !gsi_end_p (gsi); ) | |
| 301 gsi_remove (&gsi, true); | |
| 302 if (remove_fallthru_edge (bb->succs)) | |
| 303 retval = true; | |
| 304 } | |
| 0 | 305 |
| 306 return retval; | |
| 307 } | |
| 308 | |
| 309 /* Return true if basic block BB does nothing except pass control | |
| 310 flow to another block and that we can safely insert a label at | |
| 311 the start of the successor block. | |
| 312 | |
| 313 As a precondition, we require that BB be not equal to | |
| 111 | 314 the entry block. */ |
| 0 | 315 |
| 316 static bool | |
| 317 tree_forwarder_block_p (basic_block bb, bool phi_wanted) | |
| 318 { | |
| 319 gimple_stmt_iterator gsi; | |
|
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320 location_t locus; |
| 0 | 321 |
| 322 /* BB must have a single outgoing edge. */ | |
| 323 if (single_succ_p (bb) != 1 | |
| 324 /* If PHI_WANTED is false, BB must not have any PHI nodes. | |
| 325 Otherwise, BB must have PHI nodes. */ | |
| 326 || gimple_seq_empty_p (phi_nodes (bb)) == phi_wanted | |
| 111 | 327 /* BB may not be a predecessor of the exit block. */ |
| 328 || single_succ (bb) == EXIT_BLOCK_PTR_FOR_FN (cfun) | |
| 0 | 329 /* Nor should this be an infinite loop. */ |
| 330 || single_succ (bb) == bb | |
| 331 /* BB may not have an abnormal outgoing edge. */ | |
| 332 || (single_succ_edge (bb)->flags & EDGE_ABNORMAL)) | |
| 333 return false; | |
| 334 | |
| 111 | 335 gcc_checking_assert (bb != ENTRY_BLOCK_PTR_FOR_FN (cfun)); |
| 0 | 336 |
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337 locus = single_succ_edge (bb)->goto_locus; |
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338 |
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339 /* There should not be an edge coming from entry, or an EH edge. */ |
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340 { |
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341 edge_iterator ei; |
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342 edge e; |
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343 |
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344 FOR_EACH_EDGE (e, ei, bb->preds) |
| 111 | 345 if (e->src == ENTRY_BLOCK_PTR_FOR_FN (cfun) || (e->flags & EDGE_EH)) |
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346 return false; |
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347 /* If goto_locus of any of the edges differs, prevent removing |
| 131 | 348 the forwarder block when not optimizing. */ |
| 349 else if (!optimize | |
| 350 && (LOCATION_LOCUS (e->goto_locus) != UNKNOWN_LOCATION | |
| 351 || LOCATION_LOCUS (locus) != UNKNOWN_LOCATION) | |
| 352 && e->goto_locus != locus) | |
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353 return false; |
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354 } |
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355 |
| 0 | 356 /* Now walk through the statements backward. We can ignore labels, |
| 357 anything else means this is not a forwarder block. */ | |
| 358 for (gsi = gsi_last_bb (bb); !gsi_end_p (gsi); gsi_prev (&gsi)) | |
| 359 { | |
| 111 | 360 gimple *stmt = gsi_stmt (gsi); |
| 0 | 361 |
| 362 switch (gimple_code (stmt)) | |
| 363 { | |
| 364 case GIMPLE_LABEL: | |
| 111 | 365 if (DECL_NONLOCAL (gimple_label_label (as_a <glabel *> (stmt)))) |
| 0 | 366 return false; |
| 131 | 367 if (!optimize |
| 368 && (gimple_has_location (stmt) | |
| 369 || LOCATION_LOCUS (locus) != UNKNOWN_LOCATION) | |
| 370 && gimple_location (stmt) != locus) | |
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371 return false; |
| 0 | 372 break; |
| 373 | |
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374 /* ??? For now, hope there's a corresponding debug |
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375 assignment at the destination. */ |
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376 case GIMPLE_DEBUG: |
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377 break; |
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378 |
| 0 | 379 default: |
| 380 return false; | |
| 381 } | |
| 382 } | |
| 383 | |
| 384 if (current_loops) | |
| 385 { | |
| 386 basic_block dest; | |
| 111 | 387 /* Protect loop headers. */ |
| 388 if (bb_loop_header_p (bb)) | |
| 0 | 389 return false; |
| 111 | 390 |
| 0 | 391 dest = EDGE_SUCC (bb, 0)->dest; |
| 111 | 392 /* Protect loop preheaders and latches if requested. */ |
| 0 | 393 if (dest->loop_father->header == dest) |
| 111 | 394 { |
| 395 if (bb->loop_father == dest->loop_father) | |
| 396 { | |
| 397 if (loops_state_satisfies_p (LOOPS_HAVE_SIMPLE_LATCHES)) | |
| 398 return false; | |
| 399 /* If bb doesn't have a single predecessor we'd make this | |
| 400 loop have multiple latches. Don't do that if that | |
| 401 would in turn require disambiguating them. */ | |
| 402 return (single_pred_p (bb) | |
| 403 || loops_state_satisfies_p | |
| 404 (LOOPS_MAY_HAVE_MULTIPLE_LATCHES)); | |
| 405 } | |
| 406 else if (bb->loop_father == loop_outer (dest->loop_father)) | |
| 407 return !loops_state_satisfies_p (LOOPS_HAVE_PREHEADERS); | |
| 408 /* Always preserve other edges into loop headers that are | |
| 409 not simple latches or preheaders. */ | |
| 410 return false; | |
| 411 } | |
| 0 | 412 } |
| 111 | 413 |
| 0 | 414 return true; |
| 415 } | |
| 416 | |
| 417 /* If all the PHI nodes in DEST have alternatives for E1 and E2 and | |
| 418 those alternatives are equal in each of the PHI nodes, then return | |
| 419 true, else return false. */ | |
| 420 | |
| 421 static bool | |
| 422 phi_alternatives_equal (basic_block dest, edge e1, edge e2) | |
| 423 { | |
| 424 int n1 = e1->dest_idx; | |
| 425 int n2 = e2->dest_idx; | |
| 111 | 426 gphi_iterator gsi; |
| 0 | 427 |
| 428 for (gsi = gsi_start_phis (dest); !gsi_end_p (gsi); gsi_next (&gsi)) | |
| 429 { | |
| 111 | 430 gphi *phi = gsi.phi (); |
| 0 | 431 tree val1 = gimple_phi_arg_def (phi, n1); |
| 432 tree val2 = gimple_phi_arg_def (phi, n2); | |
| 433 | |
| 434 gcc_assert (val1 != NULL_TREE); | |
| 435 gcc_assert (val2 != NULL_TREE); | |
| 436 | |
| 437 if (!operand_equal_for_phi_arg_p (val1, val2)) | |
| 438 return false; | |
| 439 } | |
| 440 | |
| 441 return true; | |
| 442 } | |
| 443 | |
| 444 /* Removes forwarder block BB. Returns false if this failed. */ | |
| 445 | |
| 446 static bool | |
| 447 remove_forwarder_block (basic_block bb) | |
| 448 { | |
| 449 edge succ = single_succ_edge (bb), e, s; | |
| 450 basic_block dest = succ->dest; | |
| 131 | 451 gimple *stmt; |
| 0 | 452 edge_iterator ei; |
| 453 gimple_stmt_iterator gsi, gsi_to; | |
|
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454 bool can_move_debug_stmts; |
| 0 | 455 |
| 456 /* We check for infinite loops already in tree_forwarder_block_p. | |
| 457 However it may happen that the infinite loop is created | |
| 458 afterwards due to removal of forwarders. */ | |
| 459 if (dest == bb) | |
| 460 return false; | |
| 461 | |
|
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462 /* If the destination block consists of a nonlocal label or is a |
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463 EH landing pad, do not merge it. */ |
| 131 | 464 stmt = first_stmt (dest); |
| 465 if (stmt) | |
| 466 if (glabel *label_stmt = dyn_cast <glabel *> (stmt)) | |
| 111 | 467 if (DECL_NONLOCAL (gimple_label_label (label_stmt)) |
| 468 || EH_LANDING_PAD_NR (gimple_label_label (label_stmt)) != 0) | |
| 469 return false; | |
| 0 | 470 |
| 471 /* If there is an abnormal edge to basic block BB, but not into | |
| 472 dest, problems might occur during removal of the phi node at out | |
| 473 of ssa due to overlapping live ranges of registers. | |
| 474 | |
| 475 If there is an abnormal edge in DEST, the problems would occur | |
| 476 anyway since cleanup_dead_labels would then merge the labels for | |
| 477 two different eh regions, and rest of exception handling code | |
| 478 does not like it. | |
| 479 | |
| 480 So if there is an abnormal edge to BB, proceed only if there is | |
| 481 no abnormal edge to DEST and there are no phi nodes in DEST. */ | |
|
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482 if (bb_has_abnormal_pred (bb) |
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483 && (bb_has_abnormal_pred (dest) |
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484 || !gimple_seq_empty_p (phi_nodes (dest)))) |
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485 return false; |
| 0 | 486 |
| 487 /* If there are phi nodes in DEST, and some of the blocks that are | |
| 488 predecessors of BB are also predecessors of DEST, check that the | |
| 489 phi node arguments match. */ | |
| 490 if (!gimple_seq_empty_p (phi_nodes (dest))) | |
| 491 { | |
| 492 FOR_EACH_EDGE (e, ei, bb->preds) | |
| 493 { | |
| 494 s = find_edge (e->src, dest); | |
| 495 if (!s) | |
| 496 continue; | |
| 497 | |
| 498 if (!phi_alternatives_equal (dest, succ, s)) | |
| 499 return false; | |
| 500 } | |
| 501 } | |
| 502 | |
| 111 | 503 can_move_debug_stmts = MAY_HAVE_DEBUG_STMTS && single_pred_p (dest); |
| 504 | |
| 505 basic_block pred = NULL; | |
| 506 if (single_pred_p (bb)) | |
| 507 pred = single_pred (bb); | |
|
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508 |
| 0 | 509 /* Redirect the edges. */ |
| 510 for (ei = ei_start (bb->preds); (e = ei_safe_edge (ei)); ) | |
| 511 { | |
| 512 bitmap_set_bit (cfgcleanup_altered_bbs, e->src->index); | |
| 513 | |
| 514 if (e->flags & EDGE_ABNORMAL) | |
| 515 { | |
| 516 /* If there is an abnormal edge, redirect it anyway, and | |
| 517 move the labels to the new block to make it legal. */ | |
| 518 s = redirect_edge_succ_nodup (e, dest); | |
| 519 } | |
| 520 else | |
| 521 s = redirect_edge_and_branch (e, dest); | |
| 522 | |
| 523 if (s == e) | |
| 524 { | |
| 525 /* Create arguments for the phi nodes, since the edge was not | |
| 526 here before. */ | |
| 111 | 527 for (gphi_iterator psi = gsi_start_phis (dest); |
| 528 !gsi_end_p (psi); | |
| 529 gsi_next (&psi)) | |
| 0 | 530 { |
| 111 | 531 gphi *phi = psi.phi (); |
|
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532 source_location l = gimple_phi_arg_location_from_edge (phi, succ); |
| 111 | 533 tree def = gimple_phi_arg_def (phi, succ->dest_idx); |
| 534 add_phi_arg (phi, unshare_expr (def), s, l); | |
| 0 | 535 } |
| 536 } | |
| 537 } | |
| 538 | |
|
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539 /* Move nonlocal labels and computed goto targets as well as user |
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540 defined labels and labels with an EH landing pad number to the |
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541 new block, so that the redirection of the abnormal edges works, |
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542 jump targets end up in a sane place and debug information for |
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543 labels is retained. */ |
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544 gsi_to = gsi_start_bb (dest); |
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545 for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); ) |
| 0 | 546 { |
| 131 | 547 stmt = gsi_stmt (gsi); |
| 548 if (is_gimple_debug (stmt)) | |
|
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549 break; |
| 131 | 550 |
| 551 /* Forwarder blocks can only contain labels and debug stmts, and | |
| 552 labels must come first, so if we get to this point, we know | |
| 553 we're looking at a label. */ | |
| 554 tree decl = gimple_label_label (as_a <glabel *> (stmt)); | |
|
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555 if (EH_LANDING_PAD_NR (decl) != 0 |
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556 || DECL_NONLOCAL (decl) |
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557 || FORCED_LABEL (decl) |
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558 || !DECL_ARTIFICIAL (decl)) |
| 131 | 559 gsi_move_before (&gsi, &gsi_to); |
|
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560 else |
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561 gsi_next (&gsi); |
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562 } |
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563 |
| 111 | 564 /* Move debug statements if the destination has a single predecessor. */ |
| 131 | 565 if (can_move_debug_stmts && !gsi_end_p (gsi)) |
|
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566 { |
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567 gsi_to = gsi_after_labels (dest); |
| 131 | 568 do |
|
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569 { |
| 111 | 570 gimple *debug = gsi_stmt (gsi); |
| 131 | 571 gcc_assert (is_gimple_debug (debug)); |
| 572 gsi_move_before (&gsi, &gsi_to); | |
|
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573 } |
| 131 | 574 while (!gsi_end_p (gsi)); |
| 0 | 575 } |
| 576 | |
| 577 bitmap_set_bit (cfgcleanup_altered_bbs, dest->index); | |
| 578 | |
| 579 /* Update the dominators. */ | |
| 580 if (dom_info_available_p (CDI_DOMINATORS)) | |
| 581 { | |
| 582 basic_block dom, dombb, domdest; | |
| 583 | |
| 584 dombb = get_immediate_dominator (CDI_DOMINATORS, bb); | |
| 585 domdest = get_immediate_dominator (CDI_DOMINATORS, dest); | |
| 586 if (domdest == bb) | |
| 587 { | |
| 588 /* Shortcut to avoid calling (relatively expensive) | |
| 589 nearest_common_dominator unless necessary. */ | |
| 590 dom = dombb; | |
| 591 } | |
| 592 else | |
| 593 dom = nearest_common_dominator (CDI_DOMINATORS, domdest, dombb); | |
| 594 | |
| 595 set_immediate_dominator (CDI_DOMINATORS, dest, dom); | |
| 596 } | |
| 597 | |
| 111 | 598 /* Adjust latch infomation of BB's parent loop as otherwise |
| 599 the cfg hook has a hard time not to kill the loop. */ | |
| 600 if (current_loops && bb->loop_father->latch == bb) | |
| 601 bb->loop_father->latch = pred; | |
| 602 | |
| 0 | 603 /* And kill the forwarder block. */ |
| 604 delete_basic_block (bb); | |
| 605 | |
| 606 return true; | |
| 607 } | |
| 608 | |
| 111 | 609 /* STMT is a call that has been discovered noreturn. Split the |
| 610 block to prepare fixing up the CFG and remove LHS. | |
| 611 Return true if cleanup-cfg needs to run. */ | |
|
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612 |
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613 bool |
| 111 | 614 fixup_noreturn_call (gimple *stmt) |
|
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615 { |
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616 basic_block bb = gimple_bb (stmt); |
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617 bool changed = false; |
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618 |
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619 if (gimple_call_builtin_p (stmt, BUILT_IN_RETURN)) |
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620 return false; |
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621 |
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622 /* First split basic block if stmt is not last. */ |
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623 if (stmt != gsi_stmt (gsi_last_bb (bb))) |
| 111 | 624 { |
| 625 if (stmt == gsi_stmt (gsi_last_nondebug_bb (bb))) | |
| 626 { | |
| 627 /* Don't split if there are only debug stmts | |
| 628 after stmt, that can result in -fcompare-debug | |
| 629 failures. Remove the debug stmts instead, | |
| 630 they should be all unreachable anyway. */ | |
| 631 gimple_stmt_iterator gsi = gsi_for_stmt (stmt); | |
| 632 for (gsi_next (&gsi); !gsi_end_p (gsi); ) | |
| 633 gsi_remove (&gsi, true); | |
| 634 } | |
| 635 else | |
| 636 { | |
| 637 split_block (bb, stmt); | |
| 638 changed = true; | |
| 639 } | |
| 640 } | |
|
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641 |
| 111 | 642 /* If there is an LHS, remove it, but only if its type has fixed size. |
| 643 The LHS will need to be recreated during RTL expansion and creating | |
| 644 temporaries of variable-sized types is not supported. Also don't | |
| 645 do this with TREE_ADDRESSABLE types, as assign_temp will abort. | |
| 646 Drop LHS regardless of TREE_ADDRESSABLE, if the function call | |
| 647 has been changed into a call that does not return a value, like | |
| 648 __builtin_unreachable or __cxa_pure_virtual. */ | |
| 649 tree lhs = gimple_call_lhs (stmt); | |
| 650 if (lhs | |
| 651 && (should_remove_lhs_p (lhs) | |
| 652 || VOID_TYPE_P (TREE_TYPE (gimple_call_fntype (stmt))))) | |
|
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653 { |
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654 gimple_call_set_lhs (stmt, NULL_TREE); |
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655 |
| 111 | 656 /* We need to fix up the SSA name to avoid checking errors. */ |
| 657 if (TREE_CODE (lhs) == SSA_NAME) | |
|
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658 { |
| 111 | 659 tree new_var = create_tmp_reg (TREE_TYPE (lhs)); |
| 660 SET_SSA_NAME_VAR_OR_IDENTIFIER (lhs, new_var); | |
| 661 SSA_NAME_DEF_STMT (lhs) = gimple_build_nop (); | |
| 662 set_ssa_default_def (cfun, new_var, lhs); | |
| 663 } | |
|
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664 |
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665 update_stmt (stmt); |
| 111 | 666 } |
| 667 | |
| 668 /* Mark the call as altering control flow. */ | |
| 669 if (!gimple_call_ctrl_altering_p (stmt)) | |
| 670 { | |
| 671 gimple_call_set_ctrl_altering (stmt, true); | |
|
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672 changed = true; |
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673 } |
| 0 | 674 |
| 675 return changed; | |
| 676 } | |
| 677 | |
| 111 | 678 /* Return true if we want to merge BB1 and BB2 into a single block. */ |
| 0 | 679 |
| 680 static bool | |
| 111 | 681 want_merge_blocks_p (basic_block bb1, basic_block bb2) |
| 0 | 682 { |
| 111 | 683 if (!can_merge_blocks_p (bb1, bb2)) |
| 0 | 684 return false; |
| 111 | 685 gimple_stmt_iterator gsi = gsi_last_nondebug_bb (bb1); |
| 686 if (gsi_end_p (gsi) || !stmt_can_terminate_bb_p (gsi_stmt (gsi))) | |
| 687 return true; | |
| 688 return bb1->count.ok_for_merging (bb2->count); | |
| 689 } | |
| 0 | 690 |
| 691 | |
| 131 | 692 /* Tries to cleanup cfg in basic block BB by merging blocks. Returns |
| 693 true if anything changes. */ | |
| 0 | 694 |
| 695 static bool | |
| 696 cleanup_tree_cfg_bb (basic_block bb) | |
| 697 { | |
|
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698 if (tree_forwarder_block_p (bb, false) |
| 0 | 699 && remove_forwarder_block (bb)) |
| 700 return true; | |
| 701 | |
| 111 | 702 /* If there is a merge opportunity with the predecessor |
| 703 do nothing now but wait until we process the predecessor. | |
| 704 This happens when we visit BBs in a non-optimal order and | |
| 705 avoids quadratic behavior with adjusting stmts BB pointer. */ | |
| 706 if (single_pred_p (bb) | |
| 707 && want_merge_blocks_p (single_pred (bb), bb)) | |
| 708 /* But make sure we _do_ visit it. When we remove unreachable paths | |
| 709 ending in a backedge we fail to mark the destinations predecessors | |
| 710 as changed. */ | |
| 711 bitmap_set_bit (cfgcleanup_altered_bbs, single_pred (bb)->index); | |
| 712 | |
| 0 | 713 /* Merging the blocks may create new opportunities for folding |
| 714 conditional branches (due to the elimination of single-valued PHI | |
| 715 nodes). */ | |
| 111 | 716 else if (single_succ_p (bb) |
| 717 && want_merge_blocks_p (bb, single_succ (bb))) | |
| 0 | 718 { |
| 719 merge_blocks (bb, single_succ (bb)); | |
| 720 return true; | |
| 721 } | |
| 722 | |
| 111 | 723 return false; |
| 0 | 724 } |
| 725 | |
| 131 | 726 /* Do cleanup_control_flow_bb in PRE order. */ |
| 0 | 727 |
| 728 static bool | |
| 131 | 729 cleanup_control_flow_pre () |
| 0 | 730 { |
| 731 bool retval = false; | |
| 732 | |
| 131 | 733 /* We want remove_edge_and_dominated_blocks to only remove edges, |
| 734 not dominated blocks which it does when dom info isn't available. | |
| 735 Pretend so. */ | |
| 736 dom_state saved_state = dom_info_state (CDI_DOMINATORS); | |
| 737 set_dom_info_availability (CDI_DOMINATORS, DOM_NONE); | |
| 0 | 738 |
| 131 | 739 auto_vec<edge_iterator, 20> stack (n_basic_blocks_for_fn (cfun) + 1); |
| 740 auto_sbitmap visited (last_basic_block_for_fn (cfun)); | |
| 741 bitmap_clear (visited); | |
| 742 | |
| 743 stack.quick_push (ei_start (ENTRY_BLOCK_PTR_FOR_FN (cfun)->succs)); | |
| 0 | 744 |
| 131 | 745 while (! stack.is_empty ()) |
| 746 { | |
| 747 /* Look at the edge on the top of the stack. */ | |
| 748 edge_iterator ei = stack.last (); | |
| 749 basic_block dest = ei_edge (ei)->dest; | |
| 111 | 750 |
| 131 | 751 if (dest != EXIT_BLOCK_PTR_FOR_FN (cfun) |
| 752 && ! bitmap_bit_p (visited, dest->index)) | |
| 753 { | |
| 754 bitmap_set_bit (visited, dest->index); | |
| 755 /* We only possibly remove edges from DEST here, leaving | |
| 756 possibly unreachable code in the IL. */ | |
| 757 retval |= cleanup_control_flow_bb (dest); | |
| 758 if (EDGE_COUNT (dest->succs) > 0) | |
| 759 stack.quick_push (ei_start (dest->succs)); | |
| 760 } | |
| 761 else | |
| 762 { | |
| 763 if (!ei_one_before_end_p (ei)) | |
| 764 ei_next (&stack.last ()); | |
| 765 else | |
| 766 stack.pop (); | |
| 767 } | |
| 111 | 768 } |
| 769 | |
| 131 | 770 set_dom_info_availability (CDI_DOMINATORS, saved_state); |
| 771 | |
| 772 /* We are deleting BBs in non-reverse dominator order, make sure | |
| 773 insert_debug_temps_for_defs is prepared for that. */ | |
| 774 if (retval) | |
| 775 free_dominance_info (CDI_DOMINATORS); | |
| 111 | 776 |
| 131 | 777 /* Remove all now (and previously) unreachable blocks. */ |
| 778 for (int i = NUM_FIXED_BLOCKS; i < last_basic_block_for_fn (cfun); ++i) | |
| 111 | 779 { |
| 131 | 780 basic_block bb = BASIC_BLOCK_FOR_FN (cfun, i); |
| 781 if (bb && !bitmap_bit_p (visited, bb->index)) | |
| 782 { | |
| 783 if (!retval) | |
| 784 free_dominance_info (CDI_DOMINATORS); | |
| 785 delete_basic_block (bb); | |
| 786 retval = true; | |
| 787 } | |
| 0 | 788 } |
| 789 | |
| 790 return retval; | |
| 791 } | |
| 792 | |
| 111 | 793 static bool |
| 794 mfb_keep_latches (edge e) | |
| 795 { | |
| 131 | 796 return !((dom_info_available_p (CDI_DOMINATORS) |
| 797 && dominated_by_p (CDI_DOMINATORS, e->src, e->dest)) | |
| 798 || (e->flags & EDGE_DFS_BACK)); | |
| 111 | 799 } |
| 0 | 800 |
| 801 /* Remove unreachable blocks and other miscellaneous clean up work. | |
| 802 Return true if the flowgraph was modified, false otherwise. */ | |
| 803 | |
| 804 static bool | |
| 805 cleanup_tree_cfg_noloop (void) | |
| 806 { | |
| 807 timevar_push (TV_TREE_CLEANUP_CFG); | |
| 808 | |
| 111 | 809 /* Ensure that we have single entries into loop headers. Otherwise |
| 810 if one of the entries is becoming a latch due to CFG cleanup | |
| 811 (from formerly being part of an irreducible region) then we mess | |
| 812 up loop fixup and associate the old loop with a different region | |
| 813 which makes niter upper bounds invalid. See for example PR80549. | |
| 814 This needs to be done before we remove trivially dead edges as | |
| 815 we need to capture the dominance state before the pending transform. */ | |
| 816 if (current_loops) | |
| 817 { | |
| 131 | 818 /* This needs backedges or dominators. */ |
| 819 if (!dom_info_available_p (CDI_DOMINATORS)) | |
| 820 mark_dfs_back_edges (); | |
| 821 | |
| 111 | 822 loop_p loop; |
| 823 unsigned i; | |
| 824 FOR_EACH_VEC_ELT (*get_loops (cfun), i, loop) | |
| 825 if (loop && loop->header) | |
| 826 { | |
| 827 basic_block bb = loop->header; | |
| 828 edge_iterator ei; | |
| 829 edge e; | |
| 830 bool found_latch = false; | |
| 831 bool any_abnormal = false; | |
| 832 unsigned n = 0; | |
| 833 /* We are only interested in preserving existing loops, but | |
| 834 we need to check whether they are still real and of course | |
| 835 if we need to add a preheader at all. */ | |
| 836 FOR_EACH_EDGE (e, ei, bb->preds) | |
| 837 { | |
| 838 if (e->flags & EDGE_ABNORMAL) | |
| 839 { | |
| 840 any_abnormal = true; | |
| 841 break; | |
| 842 } | |
| 131 | 843 if ((dom_info_available_p (CDI_DOMINATORS) |
| 844 && dominated_by_p (CDI_DOMINATORS, e->src, bb)) | |
| 845 || (e->flags & EDGE_DFS_BACK)) | |
| 111 | 846 { |
| 847 found_latch = true; | |
| 848 continue; | |
| 849 } | |
| 850 n++; | |
| 851 } | |
| 852 /* If we have more than one entry to the loop header | |
| 853 create a forwarder. */ | |
| 854 if (found_latch && ! any_abnormal && n > 1) | |
| 855 { | |
| 856 edge fallthru = make_forwarder_block (bb, mfb_keep_latches, | |
| 857 NULL); | |
| 858 loop->header = fallthru->dest; | |
| 859 if (! loops_state_satisfies_p (LOOPS_NEED_FIXUP)) | |
| 860 { | |
| 861 /* The loop updating from the CFG hook is incomplete | |
| 862 when we have multiple latches, fixup manually. */ | |
| 863 remove_bb_from_loops (fallthru->src); | |
| 864 loop_p cloop = loop; | |
| 865 FOR_EACH_EDGE (e, ei, fallthru->src->preds) | |
| 866 cloop = find_common_loop (cloop, e->src->loop_father); | |
| 867 add_bb_to_loop (fallthru->src, cloop); | |
| 868 } | |
| 869 } | |
| 870 } | |
| 871 } | |
| 872 | |
| 131 | 873 /* Prepare the worklists of altered blocks. */ |
| 874 cfgcleanup_altered_bbs = BITMAP_ALLOC (NULL); | |
| 875 | |
| 876 /* Start by iterating over all basic blocks in PRE order looking for | |
| 877 edge removal opportunities. Do this first because incoming SSA form | |
| 878 may be invalid and we want to avoid performing SSA related tasks such | |
| 879 as propgating out a PHI node during BB merging in that state. This | |
| 880 also gets rid of unreachable blocks. */ | |
| 881 bool changed = cleanup_control_flow_pre (); | |
| 882 | |
| 883 /* After doing the above SSA form should be valid (or an update SSA | |
| 884 should be required). */ | |
| 885 | |
| 886 /* Compute dominator info which we need for the iterative process below. */ | |
| 887 if (!dom_info_available_p (CDI_DOMINATORS)) | |
| 888 calculate_dominance_info (CDI_DOMINATORS); | |
| 889 else | |
| 890 checking_verify_dominators (CDI_DOMINATORS); | |
| 891 | |
| 892 /* During forwarder block cleanup, we may redirect edges out of | |
| 893 SWITCH_EXPRs, which can get expensive. So we want to enable | |
| 894 recording of edge to CASE_LABEL_EXPR. */ | |
| 895 start_recording_case_labels (); | |
| 896 | |
| 897 /* Continue by iterating over all basic blocks looking for BB merging | |
| 898 opportunities. We cannot use FOR_EACH_BB_FN for the BB iteration | |
| 899 since the basic blocks may get removed. */ | |
| 900 unsigned n = last_basic_block_for_fn (cfun); | |
| 901 for (unsigned i = NUM_FIXED_BLOCKS; i < n; i++) | |
| 902 { | |
| 903 basic_block bb = BASIC_BLOCK_FOR_FN (cfun, i); | |
| 904 if (bb) | |
| 905 changed |= cleanup_tree_cfg_bb (bb); | |
| 906 } | |
| 907 | |
| 908 /* Now process the altered blocks, as long as any are available. */ | |
| 909 while (!bitmap_empty_p (cfgcleanup_altered_bbs)) | |
| 910 { | |
| 911 unsigned i = bitmap_first_set_bit (cfgcleanup_altered_bbs); | |
| 912 bitmap_clear_bit (cfgcleanup_altered_bbs, i); | |
| 913 if (i < NUM_FIXED_BLOCKS) | |
| 914 continue; | |
| 915 | |
| 916 basic_block bb = BASIC_BLOCK_FOR_FN (cfun, i); | |
| 917 if (!bb) | |
| 918 continue; | |
| 919 | |
| 920 /* BB merging done by cleanup_tree_cfg_bb can end up propagating | |
| 921 out single-argument PHIs which in turn can expose | |
| 922 cleanup_control_flow_bb opportunities so we have to repeat | |
| 923 that here. */ | |
| 924 changed |= cleanup_control_flow_bb (bb); | |
| 925 changed |= cleanup_tree_cfg_bb (bb); | |
| 926 } | |
| 927 | |
| 928 end_recording_case_labels (); | |
| 929 BITMAP_FREE (cfgcleanup_altered_bbs); | |
| 0 | 930 |
| 931 gcc_assert (dom_info_available_p (CDI_DOMINATORS)); | |
| 932 | |
| 111 | 933 /* Do not renumber blocks if the SCEV cache is active, it is indexed by |
| 934 basic-block numbers. */ | |
| 935 if (! scev_initialized_p ()) | |
| 936 compact_blocks (); | |
| 937 | |
| 938 checking_verify_flow_info (); | |
| 0 | 939 |
| 940 timevar_pop (TV_TREE_CLEANUP_CFG); | |
| 941 | |
| 942 if (changed && current_loops) | |
| 111 | 943 { |
| 944 /* Removing edges and/or blocks may make recorded bounds refer | |
| 945 to stale GIMPLE stmts now, so clear them. */ | |
| 946 free_numbers_of_iterations_estimates (cfun); | |
| 947 loops_state_set (LOOPS_NEED_FIXUP); | |
| 948 } | |
| 0 | 949 |
| 950 return changed; | |
| 951 } | |
| 952 | |
| 953 /* Repairs loop structures. */ | |
| 954 | |
| 955 static void | |
| 956 repair_loop_structures (void) | |
| 957 { | |
|
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958 bitmap changed_bbs; |
| 111 | 959 unsigned n_new_loops; |
| 960 | |
| 961 calculate_dominance_info (CDI_DOMINATORS); | |
|
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962 |
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963 timevar_push (TV_REPAIR_LOOPS); |
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964 changed_bbs = BITMAP_ALLOC (NULL); |
| 111 | 965 n_new_loops = fix_loop_structure (changed_bbs); |
| 0 | 966 |
| 967 /* This usually does nothing. But sometimes parts of cfg that originally | |
| 968 were inside a loop get out of it due to edge removal (since they | |
| 111 | 969 become unreachable by back edges from latch). Also a former |
| 970 irreducible loop can become reducible - in this case force a full | |
| 971 rewrite into loop-closed SSA form. */ | |
| 0 | 972 if (loops_state_satisfies_p (LOOP_CLOSED_SSA)) |
| 111 | 973 rewrite_into_loop_closed_ssa (n_new_loops ? NULL : changed_bbs, |
| 974 TODO_update_ssa); | |
| 0 | 975 |
| 976 BITMAP_FREE (changed_bbs); | |
| 977 | |
| 111 | 978 checking_verify_loop_structure (); |
| 0 | 979 scev_reset (); |
| 980 | |
|
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|
981 timevar_pop (TV_REPAIR_LOOPS); |
| 0 | 982 } |
| 983 | |
| 984 /* Cleanup cfg and repair loop structures. */ | |
| 985 | |
| 986 bool | |
| 987 cleanup_tree_cfg (void) | |
| 988 { | |
| 989 bool changed = cleanup_tree_cfg_noloop (); | |
| 990 | |
| 991 if (current_loops != NULL | |
| 992 && loops_state_satisfies_p (LOOPS_NEED_FIXUP)) | |
| 993 repair_loop_structures (); | |
| 994 | |
| 995 return changed; | |
| 996 } | |
| 997 | |
| 111 | 998 /* Tries to merge the PHI nodes at BB into those at BB's sole successor. |
| 999 Returns true if successful. */ | |
| 0 | 1000 |
| 111 | 1001 static bool |
| 0 | 1002 remove_forwarder_block_with_phi (basic_block bb) |
| 1003 { | |
| 1004 edge succ = single_succ_edge (bb); | |
| 1005 basic_block dest = succ->dest; | |
| 111 | 1006 gimple *label; |
| 0 | 1007 basic_block dombb, domdest, dom; |
| 1008 | |
| 1009 /* We check for infinite loops already in tree_forwarder_block_p. | |
| 1010 However it may happen that the infinite loop is created | |
| 1011 afterwards due to removal of forwarders. */ | |
| 1012 if (dest == bb) | |
| 111 | 1013 return false; |
| 1014 | |
| 1015 /* Removal of forwarders may expose new natural loops and thus | |
| 1016 a block may turn into a loop header. */ | |
| 1017 if (current_loops && bb_loop_header_p (bb)) | |
| 1018 return false; | |
| 0 | 1019 |
| 1020 /* If the destination block consists of a nonlocal label, do not | |
| 1021 merge it. */ | |
| 1022 label = first_stmt (dest); | |
| 111 | 1023 if (label) |
| 1024 if (glabel *label_stmt = dyn_cast <glabel *> (label)) | |
| 1025 if (DECL_NONLOCAL (gimple_label_label (label_stmt))) | |
| 1026 return false; | |
| 1027 | |
| 1028 /* Record BB's single pred in case we need to update the father | |
| 1029 loop's latch information later. */ | |
| 1030 basic_block pred = NULL; | |
| 1031 if (single_pred_p (bb)) | |
| 1032 pred = single_pred (bb); | |
| 0 | 1033 |
| 1034 /* Redirect each incoming edge to BB to DEST. */ | |
| 1035 while (EDGE_COUNT (bb->preds) > 0) | |
| 1036 { | |
| 1037 edge e = EDGE_PRED (bb, 0), s; | |
| 111 | 1038 gphi_iterator gsi; |
| 0 | 1039 |
| 1040 s = find_edge (e->src, dest); | |
| 1041 if (s) | |
| 1042 { | |
| 1043 /* We already have an edge S from E->src to DEST. If S and | |
| 1044 E->dest's sole successor edge have the same PHI arguments | |
| 1045 at DEST, redirect S to DEST. */ | |
| 1046 if (phi_alternatives_equal (dest, s, succ)) | |
| 1047 { | |
| 1048 e = redirect_edge_and_branch (e, dest); | |
| 1049 redirect_edge_var_map_clear (e); | |
| 1050 continue; | |
| 1051 } | |
| 1052 | |
| 1053 /* PHI arguments are different. Create a forwarder block by | |
| 1054 splitting E so that we can merge PHI arguments on E to | |
| 1055 DEST. */ | |
| 1056 e = single_succ_edge (split_edge (e)); | |
| 1057 } | |
| 111 | 1058 else |
| 1059 { | |
| 1060 /* If we merge the forwarder into a loop header verify if we | |
| 1061 are creating another loop latch edge. If so, reset | |
| 1062 number of iteration information of the loop. */ | |
| 1063 if (dest->loop_father->header == dest | |
| 1064 && dominated_by_p (CDI_DOMINATORS, e->src, dest)) | |
| 1065 { | |
| 1066 dest->loop_father->any_upper_bound = false; | |
| 1067 dest->loop_father->any_likely_upper_bound = false; | |
| 1068 free_numbers_of_iterations_estimates (dest->loop_father); | |
| 1069 } | |
| 1070 } | |
| 0 | 1071 |
| 1072 s = redirect_edge_and_branch (e, dest); | |
| 1073 | |
| 1074 /* redirect_edge_and_branch must not create a new edge. */ | |
| 1075 gcc_assert (s == e); | |
| 1076 | |
| 1077 /* Add to the PHI nodes at DEST each PHI argument removed at the | |
| 1078 destination of E. */ | |
| 1079 for (gsi = gsi_start_phis (dest); | |
| 1080 !gsi_end_p (gsi); | |
| 1081 gsi_next (&gsi)) | |
| 1082 { | |
| 111 | 1083 gphi *phi = gsi.phi (); |
| 0 | 1084 tree def = gimple_phi_arg_def (phi, succ->dest_idx); |
|
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1085 source_location locus = gimple_phi_arg_location_from_edge (phi, succ); |
| 0 | 1086 |
| 1087 if (TREE_CODE (def) == SSA_NAME) | |
| 1088 { | |
| 1089 /* If DEF is one of the results of PHI nodes removed during | |
| 1090 redirection, replace it with the PHI argument that used | |
| 1091 to be on E. */ | |
| 111 | 1092 vec<edge_var_map> *head = redirect_edge_var_map_vector (e); |
| 1093 size_t length = head ? head->length () : 0; | |
| 1094 for (size_t i = 0; i < length; i++) | |
| 0 | 1095 { |
| 111 | 1096 edge_var_map *vm = &(*head)[i]; |
| 0 | 1097 tree old_arg = redirect_edge_var_map_result (vm); |
| 1098 tree new_arg = redirect_edge_var_map_def (vm); | |
| 1099 | |
| 1100 if (def == old_arg) | |
| 1101 { | |
| 1102 def = new_arg; | |
|
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1103 locus = redirect_edge_var_map_location (vm); |
| 0 | 1104 break; |
| 1105 } | |
| 1106 } | |
| 1107 } | |
| 1108 | |
|
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|
1109 add_phi_arg (phi, def, s, locus); |
| 0 | 1110 } |
| 1111 | |
| 1112 redirect_edge_var_map_clear (e); | |
| 1113 } | |
| 1114 | |
| 1115 /* Update the dominators. */ | |
| 1116 dombb = get_immediate_dominator (CDI_DOMINATORS, bb); | |
| 1117 domdest = get_immediate_dominator (CDI_DOMINATORS, dest); | |
| 1118 if (domdest == bb) | |
| 1119 { | |
| 1120 /* Shortcut to avoid calling (relatively expensive) | |
| 1121 nearest_common_dominator unless necessary. */ | |
| 1122 dom = dombb; | |
| 1123 } | |
| 1124 else | |
| 1125 dom = nearest_common_dominator (CDI_DOMINATORS, domdest, dombb); | |
| 1126 | |
| 1127 set_immediate_dominator (CDI_DOMINATORS, dest, dom); | |
| 1128 | |
| 111 | 1129 /* Adjust latch infomation of BB's parent loop as otherwise |
| 1130 the cfg hook has a hard time not to kill the loop. */ | |
| 1131 if (current_loops && bb->loop_father->latch == bb) | |
| 1132 bb->loop_father->latch = pred; | |
| 1133 | |
| 0 | 1134 /* Remove BB since all of BB's incoming edges have been redirected |
| 1135 to DEST. */ | |
| 1136 delete_basic_block (bb); | |
| 111 | 1137 |
| 1138 return true; | |
| 0 | 1139 } |
| 1140 | |
| 1141 /* This pass merges PHI nodes if one feeds into another. For example, | |
| 1142 suppose we have the following: | |
| 1143 | |
| 1144 goto <bb 9> (<L9>); | |
| 1145 | |
| 1146 <L8>:; | |
| 1147 tem_17 = foo (); | |
| 1148 | |
| 1149 # tem_6 = PHI <tem_17(8), tem_23(7)>; | |
| 1150 <L9>:; | |
| 1151 | |
| 1152 # tem_3 = PHI <tem_6(9), tem_2(5)>; | |
| 1153 <L10>:; | |
| 1154 | |
| 1155 Then we merge the first PHI node into the second one like so: | |
| 1156 | |
| 1157 goto <bb 9> (<L10>); | |
| 1158 | |
| 1159 <L8>:; | |
| 1160 tem_17 = foo (); | |
| 1161 | |
| 1162 # tem_3 = PHI <tem_23(7), tem_2(5), tem_17(8)>; | |
| 1163 <L10>:; | |
| 1164 */ | |
| 1165 | |
| 111 | 1166 namespace { |
| 1167 | |
| 1168 const pass_data pass_data_merge_phi = | |
| 0 | 1169 { |
| 111 | 1170 GIMPLE_PASS, /* type */ |
| 1171 "mergephi", /* name */ | |
| 1172 OPTGROUP_NONE, /* optinfo_flags */ | |
| 1173 TV_TREE_MERGE_PHI, /* tv_id */ | |
| 1174 ( PROP_cfg | PROP_ssa ), /* properties_required */ | |
| 1175 0, /* properties_provided */ | |
| 1176 0, /* properties_destroyed */ | |
| 1177 0, /* todo_flags_start */ | |
| 1178 0, /* todo_flags_finish */ | |
| 1179 }; | |
| 1180 | |
| 1181 class pass_merge_phi : public gimple_opt_pass | |
| 1182 { | |
| 1183 public: | |
| 1184 pass_merge_phi (gcc::context *ctxt) | |
| 1185 : gimple_opt_pass (pass_data_merge_phi, ctxt) | |
| 1186 {} | |
| 1187 | |
| 1188 /* opt_pass methods: */ | |
| 1189 opt_pass * clone () { return new pass_merge_phi (m_ctxt); } | |
| 1190 virtual unsigned int execute (function *); | |
| 1191 | |
| 1192 }; // class pass_merge_phi | |
| 1193 | |
| 1194 unsigned int | |
| 1195 pass_merge_phi::execute (function *fun) | |
| 1196 { | |
| 1197 basic_block *worklist = XNEWVEC (basic_block, n_basic_blocks_for_fn (fun)); | |
| 0 | 1198 basic_block *current = worklist; |
| 1199 basic_block bb; | |
| 1200 | |
| 1201 calculate_dominance_info (CDI_DOMINATORS); | |
| 1202 | |
| 1203 /* Find all PHI nodes that we may be able to merge. */ | |
| 111 | 1204 FOR_EACH_BB_FN (bb, fun) |
| 0 | 1205 { |
| 1206 basic_block dest; | |
| 1207 | |
| 1208 /* Look for a forwarder block with PHI nodes. */ | |
| 1209 if (!tree_forwarder_block_p (bb, true)) | |
| 1210 continue; | |
| 1211 | |
| 1212 dest = single_succ (bb); | |
| 1213 | |
| 1214 /* We have to feed into another basic block with PHI | |
| 1215 nodes. */ | |
|
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changeset
|
1216 if (gimple_seq_empty_p (phi_nodes (dest)) |
| 0 | 1217 /* We don't want to deal with a basic block with |
| 1218 abnormal edges. */ | |
|
67
f6334be47118
update gcc from gcc-4.6-20100522 to gcc-4.6-20110318
nobuyasu <dimolto@cr.ie.u-ryukyu.ac.jp>
parents:
63
diff
changeset
|
1219 || bb_has_abnormal_pred (bb)) |
| 0 | 1220 continue; |
| 1221 | |
| 1222 if (!dominated_by_p (CDI_DOMINATORS, dest, bb)) | |
| 1223 { | |
| 1224 /* If BB does not dominate DEST, then the PHI nodes at | |
| 1225 DEST must be the only users of the results of the PHI | |
| 1226 nodes at BB. */ | |
| 1227 *current++ = bb; | |
| 1228 } | |
| 1229 else | |
| 1230 { | |
| 111 | 1231 gphi_iterator gsi; |
| 0 | 1232 unsigned int dest_idx = single_succ_edge (bb)->dest_idx; |
| 1233 | |
| 1234 /* BB dominates DEST. There may be many users of the PHI | |
| 1235 nodes in BB. However, there is still a trivial case we | |
| 1236 can handle. If the result of every PHI in BB is used | |
| 1237 only by a PHI in DEST, then we can trivially merge the | |
| 1238 PHI nodes from BB into DEST. */ | |
| 1239 for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); | |
| 1240 gsi_next (&gsi)) | |
| 1241 { | |
| 111 | 1242 gphi *phi = gsi.phi (); |
| 0 | 1243 tree result = gimple_phi_result (phi); |
| 1244 use_operand_p imm_use; | |
| 111 | 1245 gimple *use_stmt; |
| 0 | 1246 |
| 1247 /* If the PHI's result is never used, then we can just | |
| 1248 ignore it. */ | |
| 1249 if (has_zero_uses (result)) | |
| 1250 continue; | |
| 1251 | |
| 1252 /* Get the single use of the result of this PHI node. */ | |
| 1253 if (!single_imm_use (result, &imm_use, &use_stmt) | |
| 1254 || gimple_code (use_stmt) != GIMPLE_PHI | |
| 1255 || gimple_bb (use_stmt) != dest | |
| 1256 || gimple_phi_arg_def (use_stmt, dest_idx) != result) | |
| 1257 break; | |
| 1258 } | |
| 1259 | |
| 1260 /* If the loop above iterated through all the PHI nodes | |
| 1261 in BB, then we can merge the PHIs from BB into DEST. */ | |
| 1262 if (gsi_end_p (gsi)) | |
| 1263 *current++ = bb; | |
| 1264 } | |
| 1265 } | |
| 1266 | |
| 1267 /* Now let's drain WORKLIST. */ | |
| 111 | 1268 bool changed = false; |
| 0 | 1269 while (current != worklist) |
| 1270 { | |
| 1271 bb = *--current; | |
| 111 | 1272 changed |= remove_forwarder_block_with_phi (bb); |
| 0 | 1273 } |
| 111 | 1274 free (worklist); |
| 0 | 1275 |
| 111 | 1276 /* Removing forwarder blocks can cause formerly irreducible loops |
| 1277 to become reducible if we merged two entry blocks. */ | |
| 1278 if (changed | |
| 1279 && current_loops) | |
| 1280 loops_state_set (LOOPS_NEED_FIXUP); | |
| 1281 | |
| 0 | 1282 return 0; |
| 1283 } | |
| 1284 | |
| 111 | 1285 } // anon namespace |
| 1286 | |
| 1287 gimple_opt_pass * | |
| 1288 make_pass_merge_phi (gcc::context *ctxt) | |
| 0 | 1289 { |
| 111 | 1290 return new pass_merge_phi (ctxt); |
| 0 | 1291 } |
| 1292 | |
| 111 | 1293 /* Pass: cleanup the CFG just before expanding trees to RTL. |
| 1294 This is just a round of label cleanups and case node grouping | |
| 1295 because after the tree optimizers have run such cleanups may | |
| 1296 be necessary. */ | |
| 1297 | |
| 1298 static unsigned int | |
| 1299 execute_cleanup_cfg_post_optimizing (void) | |
| 0 | 1300 { |
| 111 | 1301 unsigned int todo = execute_fixup_cfg (); |
| 1302 if (cleanup_tree_cfg ()) | |
| 1303 { | |
| 1304 todo &= ~TODO_cleanup_cfg; | |
| 1305 todo |= TODO_update_ssa; | |
| 1306 } | |
| 1307 maybe_remove_unreachable_handlers (); | |
| 1308 cleanup_dead_labels (); | |
| 1309 if (group_case_labels ()) | |
| 1310 todo |= TODO_cleanup_cfg; | |
| 1311 if ((flag_compare_debug_opt || flag_compare_debug) | |
| 1312 && flag_dump_final_insns) | |
| 1313 { | |
| 1314 FILE *final_output = fopen (flag_dump_final_insns, "a"); | |
| 1315 | |
| 1316 if (!final_output) | |
| 1317 { | |
| 1318 error ("could not open final insn dump file %qs: %m", | |
| 1319 flag_dump_final_insns); | |
| 1320 flag_dump_final_insns = NULL; | |
| 1321 } | |
| 1322 else | |
| 1323 { | |
| 1324 int save_unnumbered = flag_dump_unnumbered; | |
| 1325 int save_noaddr = flag_dump_noaddr; | |
| 1326 | |
| 1327 flag_dump_noaddr = flag_dump_unnumbered = 1; | |
| 1328 fprintf (final_output, "\n"); | |
| 131 | 1329 dump_enumerated_decls (final_output, |
| 1330 dump_flags | TDF_SLIM | TDF_NOUID); | |
| 111 | 1331 flag_dump_noaddr = save_noaddr; |
| 1332 flag_dump_unnumbered = save_unnumbered; | |
| 1333 if (fclose (final_output)) | |
| 1334 { | |
| 1335 error ("could not close final insn dump file %qs: %m", | |
| 1336 flag_dump_final_insns); | |
| 1337 flag_dump_final_insns = NULL; | |
| 1338 } | |
| 1339 } | |
| 1340 } | |
| 1341 return todo; | |
| 1342 } | |
| 1343 | |
| 1344 namespace { | |
| 1345 | |
| 1346 const pass_data pass_data_cleanup_cfg_post_optimizing = | |
| 1347 { | |
| 1348 GIMPLE_PASS, /* type */ | |
| 1349 "optimized", /* name */ | |
| 1350 OPTGROUP_NONE, /* optinfo_flags */ | |
| 1351 TV_TREE_CLEANUP_CFG, /* tv_id */ | |
| 1352 PROP_cfg, /* properties_required */ | |
| 1353 0, /* properties_provided */ | |
| 1354 0, /* properties_destroyed */ | |
| 1355 0, /* todo_flags_start */ | |
| 1356 TODO_remove_unused_locals, /* todo_flags_finish */ | |
| 0 | 1357 }; |
| 111 | 1358 |
| 1359 class pass_cleanup_cfg_post_optimizing : public gimple_opt_pass | |
| 1360 { | |
| 1361 public: | |
| 1362 pass_cleanup_cfg_post_optimizing (gcc::context *ctxt) | |
| 1363 : gimple_opt_pass (pass_data_cleanup_cfg_post_optimizing, ctxt) | |
| 1364 {} | |
| 1365 | |
| 1366 /* opt_pass methods: */ | |
| 1367 virtual unsigned int execute (function *) | |
| 1368 { | |
| 1369 return execute_cleanup_cfg_post_optimizing (); | |
| 1370 } | |
| 1371 | |
| 1372 }; // class pass_cleanup_cfg_post_optimizing | |
| 1373 | |
| 1374 } // anon namespace | |
| 1375 | |
| 1376 gimple_opt_pass * | |
| 1377 make_pass_cleanup_cfg_post_optimizing (gcc::context *ctxt) | |
| 1378 { | |
| 1379 return new pass_cleanup_cfg_post_optimizing (ctxt); | |
| 1380 } | |
| 1381 | |
| 1382 |