Mercurial > hg > CbC > CbC_gcc
annotate gcc/tree-ssa-copy.c @ 158:494b0b89df80 default tip
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| author | Shinji KONO <kono@ie.u-ryukyu.ac.jp> |
|---|---|
| date | Mon, 25 May 2020 18:13:55 +0900 |
| parents | 1830386684a0 |
| children |
| rev | line source |
|---|---|
| 0 | 1 /* Copy propagation and SSA_NAME replacement support routines. |
| 145 | 2 Copyright (C) 2004-2020 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" |
| 0 | 24 #include "tree.h" |
| 111 | 25 #include "gimple.h" |
| 26 #include "tree-pass.h" | |
| 27 #include "ssa.h" | |
|
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28 #include "gimple-pretty-print.h" |
| 111 | 29 #include "fold-const.h" |
| 30 #include "gimple-iterator.h" | |
| 31 #include "tree-cfg.h" | |
| 0 | 32 #include "tree-ssa-propagate.h" |
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33 #include "cfgloop.h" |
| 111 | 34 #include "tree-scalar-evolution.h" |
| 35 #include "tree-ssa-loop-niter.h" | |
| 36 | |
| 0 | 37 |
| 38 /* This file implements the copy propagation pass and provides a | |
| 39 handful of interfaces for performing const/copy propagation and | |
| 40 simple expression replacement which keep variable annotations | |
| 41 up-to-date. | |
| 42 | |
| 43 We require that for any copy operation where the RHS and LHS have | |
| 44 a non-null memory tag the memory tag be the same. It is OK | |
| 45 for one or both of the memory tags to be NULL. | |
| 46 | |
| 47 We also require tracking if a variable is dereferenced in a load or | |
| 48 store operation. | |
| 49 | |
| 50 We enforce these requirements by having all copy propagation and | |
| 51 replacements of one SSA_NAME with a different SSA_NAME to use the | |
| 52 APIs defined in this file. */ | |
| 53 | |
| 54 /*--------------------------------------------------------------------------- | |
| 55 Copy propagation | |
| 56 ---------------------------------------------------------------------------*/ | |
|
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57 /* Lattice for copy-propagation. The lattice is initialized to |
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58 UNDEFINED (value == NULL) for SSA names that can become a copy |
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59 of something or VARYING (value == self) if not (see get_copy_of_val |
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60 and stmt_may_generate_copy). Other values make the name a COPY |
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61 of that value. |
| 0 | 62 |
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63 When visiting a statement or PHI node the lattice value for an |
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64 SSA name can transition from UNDEFINED to COPY to VARYING. */ |
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65 |
| 111 | 66 struct prop_value_t { |
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67 /* Copy-of value. */ |
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68 tree value; |
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69 }; |
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70 |
| 131 | 71 class copy_prop : public ssa_propagation_engine |
| 72 { | |
| 73 public: | |
| 74 enum ssa_prop_result visit_stmt (gimple *, edge *, tree *) FINAL OVERRIDE; | |
| 75 enum ssa_prop_result visit_phi (gphi *) FINAL OVERRIDE; | |
| 76 }; | |
| 77 | |
| 0 | 78 static prop_value_t *copy_of; |
| 111 | 79 static unsigned n_copy_of; |
| 0 | 80 |
| 81 | |
| 82 /* Return true if this statement may generate a useful copy. */ | |
| 83 | |
| 84 static bool | |
| 111 | 85 stmt_may_generate_copy (gimple *stmt) |
| 0 | 86 { |
| 87 if (gimple_code (stmt) == GIMPLE_PHI) | |
| 88 return !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (gimple_phi_result (stmt)); | |
| 89 | |
| 90 if (gimple_code (stmt) != GIMPLE_ASSIGN) | |
| 91 return false; | |
| 92 | |
| 93 /* If the statement has volatile operands, it won't generate a | |
| 94 useful copy. */ | |
| 95 if (gimple_has_volatile_ops (stmt)) | |
| 96 return false; | |
| 97 | |
| 98 /* Statements with loads and/or stores will never generate a useful copy. */ | |
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99 if (gimple_vuse (stmt)) |
| 0 | 100 return false; |
| 101 | |
| 102 /* Otherwise, the only statements that generate useful copies are | |
| 103 assignments whose RHS is just an SSA name that doesn't flow | |
| 104 through abnormal edges. */ | |
| 111 | 105 return ((gimple_assign_rhs_code (stmt) == SSA_NAME |
| 106 && !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (gimple_assign_rhs1 (stmt))) | |
| 107 || is_gimple_min_invariant (gimple_assign_rhs1 (stmt))); | |
| 0 | 108 } |
| 109 | |
| 110 | |
| 111 /* Return the copy-of value for VAR. */ | |
| 112 | |
| 113 static inline prop_value_t * | |
| 114 get_copy_of_val (tree var) | |
| 115 { | |
| 116 prop_value_t *val = ©_of[SSA_NAME_VERSION (var)]; | |
| 117 | |
| 118 if (val->value == NULL_TREE | |
| 119 && !stmt_may_generate_copy (SSA_NAME_DEF_STMT (var))) | |
| 120 { | |
| 121 /* If the variable will never generate a useful copy relation, | |
| 122 make it its own copy. */ | |
| 123 val->value = var; | |
| 124 } | |
| 125 | |
| 126 return val; | |
| 127 } | |
| 128 | |
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129 /* Return the variable VAR is a copy of or VAR if VAR isn't the result |
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130 of a copy. */ |
| 0 | 131 |
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132 static inline tree |
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133 valueize_val (tree var) |
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134 { |
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135 if (TREE_CODE (var) == SSA_NAME) |
| 0 | 136 { |
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137 tree val = get_copy_of_val (var)->value; |
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138 if (val) |
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139 return val; |
| 0 | 140 } |
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141 return var; |
| 0 | 142 } |
| 143 | |
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144 /* Set VAL to be the copy of VAR. If that changed return true. */ |
| 0 | 145 |
| 146 static inline bool | |
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147 set_copy_of_val (tree var, tree val) |
| 0 | 148 { |
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149 unsigned int ver = SSA_NAME_VERSION (var); |
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150 tree old; |
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151 |
| 0 | 152 /* Set FIRST to be the first link in COPY_OF[DEST]. If that |
| 153 changed, return true. */ | |
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154 old = copy_of[ver].value; |
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155 copy_of[ver].value = val; |
| 0 | 156 |
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157 if (old != val |
| 131 | 158 && (!old || !operand_equal_p (old, val, 0))) |
| 0 | 159 return true; |
| 160 | |
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161 return false; |
| 0 | 162 } |
| 163 | |
| 164 | |
| 165 /* Dump the copy-of value for variable VAR to FILE. */ | |
| 166 | |
| 167 static void | |
| 168 dump_copy_of (FILE *file, tree var) | |
| 169 { | |
| 170 tree val; | |
| 171 | |
| 172 print_generic_expr (file, var, dump_flags); | |
| 173 if (TREE_CODE (var) != SSA_NAME) | |
| 174 return; | |
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175 |
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176 val = copy_of[SSA_NAME_VERSION (var)].value; |
| 0 | 177 fprintf (file, " copy-of chain: "); |
| 111 | 178 print_generic_expr (file, var); |
| 0 | 179 fprintf (file, " "); |
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180 if (!val) |
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181 fprintf (file, "[UNDEFINED]"); |
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182 else if (val == var) |
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183 fprintf (file, "[NOT A COPY]"); |
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184 else |
| 0 | 185 { |
| 186 fprintf (file, "-> "); | |
| 111 | 187 print_generic_expr (file, val); |
| 0 | 188 fprintf (file, " "); |
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189 fprintf (file, "[COPY]"); |
| 0 | 190 } |
| 191 } | |
| 192 | |
| 193 | |
| 194 /* Evaluate the RHS of STMT. If it produces a valid copy, set the LHS | |
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195 value and store the LHS into *RESULT_P. */ |
| 0 | 196 |
| 197 static enum ssa_prop_result | |
| 111 | 198 copy_prop_visit_assignment (gimple *stmt, tree *result_p) |
| 0 | 199 { |
| 200 tree lhs, rhs; | |
| 201 | |
| 202 lhs = gimple_assign_lhs (stmt); | |
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203 rhs = valueize_val (gimple_assign_rhs1 (stmt)); |
| 0 | 204 |
| 205 if (TREE_CODE (lhs) == SSA_NAME) | |
| 206 { | |
| 207 /* Straight copy between two SSA names. First, make sure that | |
| 208 we can propagate the RHS into uses of LHS. */ | |
| 209 if (!may_propagate_copy (lhs, rhs)) | |
| 210 return SSA_PROP_VARYING; | |
| 211 | |
| 212 *result_p = lhs; | |
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213 if (set_copy_of_val (*result_p, rhs)) |
| 0 | 214 return SSA_PROP_INTERESTING; |
| 215 else | |
| 216 return SSA_PROP_NOT_INTERESTING; | |
| 217 } | |
| 218 | |
| 219 return SSA_PROP_VARYING; | |
| 220 } | |
| 221 | |
| 222 | |
| 223 /* Visit the GIMPLE_COND STMT. Return SSA_PROP_INTERESTING | |
| 224 if it can determine which edge will be taken. Otherwise, return | |
| 225 SSA_PROP_VARYING. */ | |
| 226 | |
| 227 static enum ssa_prop_result | |
| 111 | 228 copy_prop_visit_cond_stmt (gimple *stmt, edge *taken_edge_p) |
| 0 | 229 { |
| 230 enum ssa_prop_result retval = SSA_PROP_VARYING; | |
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231 location_t loc = gimple_location (stmt); |
| 0 | 232 |
| 111 | 233 tree op0 = valueize_val (gimple_cond_lhs (stmt)); |
| 234 tree op1 = valueize_val (gimple_cond_rhs (stmt)); | |
| 0 | 235 |
| 111 | 236 /* See if we can determine the predicate's value. */ |
| 237 if (dump_file && (dump_flags & TDF_DETAILS)) | |
| 238 { | |
| 239 fprintf (dump_file, "Trying to determine truth value of "); | |
| 240 fprintf (dump_file, "predicate "); | |
| 241 print_gimple_stmt (dump_file, stmt, 0); | |
| 242 } | |
| 0 | 243 |
| 111 | 244 /* Fold COND and see whether we get a useful result. */ |
| 245 tree folded_cond = fold_binary_loc (loc, gimple_cond_code (stmt), | |
| 246 boolean_type_node, op0, op1); | |
| 247 if (folded_cond) | |
| 248 { | |
| 249 basic_block bb = gimple_bb (stmt); | |
| 250 *taken_edge_p = find_taken_edge (bb, folded_cond); | |
| 251 if (*taken_edge_p) | |
| 252 retval = SSA_PROP_INTERESTING; | |
| 0 | 253 } |
| 254 | |
| 255 if (dump_file && (dump_flags & TDF_DETAILS) && *taken_edge_p) | |
| 256 fprintf (dump_file, "\nConditional will always take edge %d->%d\n", | |
| 257 (*taken_edge_p)->src->index, (*taken_edge_p)->dest->index); | |
| 258 | |
| 259 return retval; | |
| 260 } | |
| 261 | |
| 262 | |
| 263 /* Evaluate statement STMT. If the statement produces a new output | |
| 264 value, return SSA_PROP_INTERESTING and store the SSA_NAME holding | |
| 265 the new value in *RESULT_P. | |
| 266 | |
| 267 If STMT is a conditional branch and we can determine its truth | |
| 268 value, set *TAKEN_EDGE_P accordingly. | |
| 269 | |
| 270 If the new value produced by STMT is varying, return | |
| 271 SSA_PROP_VARYING. */ | |
| 272 | |
| 131 | 273 enum ssa_prop_result |
| 274 copy_prop::visit_stmt (gimple *stmt, edge *taken_edge_p, tree *result_p) | |
| 0 | 275 { |
| 276 enum ssa_prop_result retval; | |
| 277 | |
| 278 if (dump_file && (dump_flags & TDF_DETAILS)) | |
| 279 { | |
| 280 fprintf (dump_file, "\nVisiting statement:\n"); | |
| 281 print_gimple_stmt (dump_file, stmt, 0, dump_flags); | |
| 282 fprintf (dump_file, "\n"); | |
| 283 } | |
| 284 | |
| 285 if (gimple_assign_single_p (stmt) | |
| 286 && TREE_CODE (gimple_assign_lhs (stmt)) == SSA_NAME | |
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287 && (TREE_CODE (gimple_assign_rhs1 (stmt)) == SSA_NAME |
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288 || is_gimple_min_invariant (gimple_assign_rhs1 (stmt)))) |
| 0 | 289 { |
| 290 /* If the statement is a copy assignment, evaluate its RHS to | |
| 291 see if the lattice value of its output has changed. */ | |
| 292 retval = copy_prop_visit_assignment (stmt, result_p); | |
| 293 } | |
| 294 else if (gimple_code (stmt) == GIMPLE_COND) | |
| 295 { | |
| 296 /* See if we can determine which edge goes out of a conditional | |
| 297 jump. */ | |
| 298 retval = copy_prop_visit_cond_stmt (stmt, taken_edge_p); | |
| 299 } | |
| 300 else | |
| 301 retval = SSA_PROP_VARYING; | |
| 302 | |
| 303 if (retval == SSA_PROP_VARYING) | |
| 304 { | |
| 305 tree def; | |
| 306 ssa_op_iter i; | |
| 307 | |
| 308 /* Any other kind of statement is not interesting for constant | |
| 309 propagation and, therefore, not worth simulating. */ | |
| 310 if (dump_file && (dump_flags & TDF_DETAILS)) | |
| 311 fprintf (dump_file, "No interesting values produced.\n"); | |
| 312 | |
| 313 /* The assignment is not a copy operation. Don't visit this | |
| 314 statement again and mark all the definitions in the statement | |
| 315 to be copies of nothing. */ | |
| 316 FOR_EACH_SSA_TREE_OPERAND (def, stmt, i, SSA_OP_ALL_DEFS) | |
| 317 set_copy_of_val (def, def); | |
| 318 } | |
| 319 | |
| 320 return retval; | |
| 321 } | |
| 322 | |
| 323 | |
| 324 /* Visit PHI node PHI. If all the arguments produce the same value, | |
| 325 set it to be the value of the LHS of PHI. */ | |
| 326 | |
| 131 | 327 enum ssa_prop_result |
| 328 copy_prop::visit_phi (gphi *phi) | |
| 0 | 329 { |
| 330 enum ssa_prop_result retval; | |
| 331 unsigned i; | |
|
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332 prop_value_t phi_val = { NULL_TREE }; |
| 0 | 333 |
| 334 tree lhs = gimple_phi_result (phi); | |
| 335 | |
| 336 if (dump_file && (dump_flags & TDF_DETAILS)) | |
| 337 { | |
| 338 fprintf (dump_file, "\nVisiting PHI node: "); | |
| 339 print_gimple_stmt (dump_file, phi, 0, dump_flags); | |
| 340 } | |
| 341 | |
| 342 for (i = 0; i < gimple_phi_num_args (phi); i++) | |
| 343 { | |
| 344 prop_value_t *arg_val; | |
| 111 | 345 tree arg_value; |
| 0 | 346 tree arg = gimple_phi_arg_def (phi, i); |
| 347 edge e = gimple_phi_arg_edge (phi, i); | |
| 348 | |
| 349 /* We don't care about values flowing through non-executable | |
| 350 edges. */ | |
| 351 if (!(e->flags & EDGE_EXECUTABLE)) | |
| 352 continue; | |
| 353 | |
| 111 | 354 /* Names that flow through abnormal edges cannot be used to |
| 355 derive copies. */ | |
| 356 if (TREE_CODE (arg) == SSA_NAME && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (arg)) | |
| 0 | 357 { |
| 358 phi_val.value = lhs; | |
| 359 break; | |
| 360 } | |
| 361 | |
| 362 if (dump_file && (dump_flags & TDF_DETAILS)) | |
| 363 { | |
| 364 fprintf (dump_file, "\tArgument #%d: ", i); | |
| 365 dump_copy_of (dump_file, arg); | |
| 366 fprintf (dump_file, "\n"); | |
| 367 } | |
| 368 | |
| 111 | 369 if (TREE_CODE (arg) == SSA_NAME) |
| 370 { | |
| 371 arg_val = get_copy_of_val (arg); | |
| 372 | |
| 373 /* If we didn't visit the definition of arg yet treat it as | |
| 374 UNDEFINED. This also handles PHI arguments that are the | |
| 375 same as lhs. We'll come here again. */ | |
| 376 if (!arg_val->value) | |
| 377 continue; | |
| 0 | 378 |
| 111 | 379 arg_value = arg_val->value; |
| 380 } | |
| 381 else | |
| 382 arg_value = valueize_val (arg); | |
| 383 | |
| 384 /* In loop-closed SSA form do not copy-propagate SSA-names across | |
| 385 loop exit edges. */ | |
| 386 if (loops_state_satisfies_p (LOOP_CLOSED_SSA) | |
| 387 && TREE_CODE (arg_value) == SSA_NAME | |
| 388 && loop_exit_edge_p (e->src->loop_father, e)) | |
| 389 { | |
| 390 phi_val.value = lhs; | |
| 391 break; | |
| 392 } | |
|
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393 |
| 0 | 394 /* If the LHS didn't have a value yet, make it a copy of the |
|
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395 first argument we find. */ |
| 0 | 396 if (phi_val.value == NULL_TREE) |
| 397 { | |
| 111 | 398 phi_val.value = arg_value; |
| 0 | 399 continue; |
| 400 } | |
| 401 | |
| 402 /* If PHI_VAL and ARG don't have a common copy-of chain, then | |
|
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403 this PHI node cannot be a copy operation. */ |
| 111 | 404 if (phi_val.value != arg_value |
| 405 && !operand_equal_p (phi_val.value, arg_value, 0)) | |
| 0 | 406 { |
| 407 phi_val.value = lhs; | |
| 408 break; | |
| 409 } | |
| 410 } | |
| 411 | |
|
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412 if (phi_val.value |
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413 && may_propagate_copy (lhs, phi_val.value) |
| 0 | 414 && set_copy_of_val (lhs, phi_val.value)) |
| 415 retval = (phi_val.value != lhs) ? SSA_PROP_INTERESTING : SSA_PROP_VARYING; | |
| 416 else | |
| 417 retval = SSA_PROP_NOT_INTERESTING; | |
| 418 | |
| 419 if (dump_file && (dump_flags & TDF_DETAILS)) | |
| 420 { | |
|
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421 fprintf (dump_file, "PHI node "); |
| 0 | 422 dump_copy_of (dump_file, lhs); |
| 423 fprintf (dump_file, "\nTelling the propagator to "); | |
| 424 if (retval == SSA_PROP_INTERESTING) | |
| 425 fprintf (dump_file, "add SSA edges out of this PHI and continue."); | |
| 426 else if (retval == SSA_PROP_VARYING) | |
| 427 fprintf (dump_file, "add SSA edges out of this PHI and never visit again."); | |
| 428 else | |
| 429 fprintf (dump_file, "do nothing with SSA edges and keep iterating."); | |
| 430 fprintf (dump_file, "\n\n"); | |
| 431 } | |
| 432 | |
| 433 return retval; | |
| 434 } | |
| 435 | |
| 436 | |
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437 /* Initialize structures used for copy propagation. */ |
| 0 | 438 |
| 439 static void | |
| 440 init_copy_prop (void) | |
| 441 { | |
| 442 basic_block bb; | |
| 443 | |
| 111 | 444 n_copy_of = num_ssa_names; |
| 445 copy_of = XCNEWVEC (prop_value_t, n_copy_of); | |
| 0 | 446 |
| 111 | 447 FOR_EACH_BB_FN (bb, cfun) |
| 0 | 448 { |
| 111 | 449 for (gimple_stmt_iterator si = gsi_start_bb (bb); !gsi_end_p (si); |
| 450 gsi_next (&si)) | |
| 0 | 451 { |
| 111 | 452 gimple *stmt = gsi_stmt (si); |
| 0 | 453 ssa_op_iter iter; |
| 454 tree def; | |
| 455 | |
| 456 /* The only statements that we care about are those that may | |
| 457 generate useful copies. We also need to mark conditional | |
| 458 jumps so that their outgoing edges are added to the work | |
| 111 | 459 lists of the propagator. */ |
| 0 | 460 if (stmt_ends_bb_p (stmt)) |
| 461 prop_set_simulate_again (stmt, true); | |
| 111 | 462 else if (stmt_may_generate_copy (stmt)) |
| 0 | 463 prop_set_simulate_again (stmt, true); |
| 464 else | |
| 465 prop_set_simulate_again (stmt, false); | |
| 466 | |
| 467 /* Mark all the outputs of this statement as not being | |
| 468 the copy of anything. */ | |
| 469 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS) | |
| 470 if (!prop_simulate_again_p (stmt)) | |
| 471 set_copy_of_val (def, def); | |
| 472 } | |
| 473 | |
| 111 | 474 for (gphi_iterator si = gsi_start_phis (bb); !gsi_end_p (si); |
| 475 gsi_next (&si)) | |
|
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476 { |
| 111 | 477 gphi *phi = si.phi (); |
| 0 | 478 tree def; |
| 479 | |
| 480 def = gimple_phi_result (phi); | |
| 111 | 481 if (virtual_operand_p (def)) |
| 0 | 482 prop_set_simulate_again (phi, false); |
| 483 else | |
| 484 prop_set_simulate_again (phi, true); | |
| 485 | |
| 486 if (!prop_simulate_again_p (phi)) | |
| 487 set_copy_of_val (def, def); | |
| 488 } | |
| 489 } | |
| 490 } | |
| 491 | |
| 131 | 492 class copy_folder : public substitute_and_fold_engine |
| 493 { | |
| 494 public: | |
| 495 tree get_value (tree) FINAL OVERRIDE; | |
| 496 }; | |
| 497 | |
|
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498 /* Callback for substitute_and_fold to get at the final copy-of values. */ |
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499 |
| 131 | 500 tree |
| 501 copy_folder::get_value (tree name) | |
|
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502 { |
| 111 | 503 tree val; |
| 504 if (SSA_NAME_VERSION (name) >= n_copy_of) | |
| 505 return NULL_TREE; | |
| 506 val = copy_of[SSA_NAME_VERSION (name)].value; | |
|
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507 if (val && val != name) |
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508 return val; |
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509 return NULL_TREE; |
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510 } |
| 0 | 511 |
| 512 /* Deallocate memory used in copy propagation and do final | |
| 513 substitution. */ | |
| 514 | |
| 111 | 515 static bool |
| 0 | 516 fini_copy_prop (void) |
| 517 { | |
|
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518 unsigned i; |
| 111 | 519 tree var; |
|
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520 |
| 0 | 521 /* Set the final copy-of value for each variable by traversing the |
| 522 copy-of chains. */ | |
| 111 | 523 FOR_EACH_SSA_NAME (i, var, cfun) |
| 0 | 524 { |
| 111 | 525 if (!copy_of[i].value |
|
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526 || copy_of[i].value == var) |
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527 continue; |
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528 |
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529 /* In theory the points-to solution of all members of the |
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530 copy chain is their intersection. For now we do not bother |
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531 to compute this but only make sure we do not lose points-to |
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532 information completely by setting the points-to solution |
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533 of the representative to the first solution we find if |
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534 it doesn't have one already. */ |
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535 if (copy_of[i].value != var |
| 111 | 536 && TREE_CODE (copy_of[i].value) == SSA_NAME) |
| 537 { | |
| 538 basic_block copy_of_bb | |
| 539 = gimple_bb (SSA_NAME_DEF_STMT (copy_of[i].value)); | |
| 540 basic_block var_bb = gimple_bb (SSA_NAME_DEF_STMT (var)); | |
| 541 if (POINTER_TYPE_P (TREE_TYPE (var)) | |
| 542 && SSA_NAME_PTR_INFO (var) | |
| 543 && !SSA_NAME_PTR_INFO (copy_of[i].value)) | |
| 544 { | |
| 545 duplicate_ssa_name_ptr_info (copy_of[i].value, | |
| 546 SSA_NAME_PTR_INFO (var)); | |
| 547 /* Points-to information is cfg insensitive, | |
| 145 | 548 but [E]VRP might record context sensitive alignment |
| 549 info, non-nullness, etc. So reset context sensitive | |
| 550 info if the two SSA_NAMEs aren't defined in the same | |
| 551 basic block. */ | |
| 111 | 552 if (var_bb != copy_of_bb) |
| 145 | 553 reset_flow_sensitive_info (copy_of[i].value); |
| 111 | 554 } |
| 555 else if (!POINTER_TYPE_P (TREE_TYPE (var)) | |
| 556 && SSA_NAME_RANGE_INFO (var) | |
| 557 && !SSA_NAME_RANGE_INFO (copy_of[i].value) | |
| 558 && var_bb == copy_of_bb) | |
| 559 duplicate_ssa_name_range_info (copy_of[i].value, | |
| 560 SSA_NAME_RANGE_TYPE (var), | |
| 561 SSA_NAME_RANGE_INFO (var)); | |
| 562 } | |
| 0 | 563 } |
| 564 | |
| 131 | 565 class copy_folder copy_folder; |
| 566 bool changed = copy_folder.substitute_and_fold (); | |
| 111 | 567 if (changed) |
| 568 { | |
| 569 free_numbers_of_iterations_estimates (cfun); | |
| 570 if (scev_initialized_p ()) | |
| 571 scev_reset (); | |
| 572 } | |
| 0 | 573 |
| 574 free (copy_of); | |
| 111 | 575 |
| 576 return changed; | |
| 0 | 577 } |
| 578 | |
| 579 | |
| 580 /* Main entry point to the copy propagator. | |
| 581 | |
| 582 PHIS_ONLY is true if we should only consider PHI nodes as generating | |
|
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583 copy propagation opportunities. |
| 0 | 584 |
| 585 The algorithm propagates the value COPY-OF using ssa_propagate. For | |
| 586 every variable X_i, COPY-OF(X_i) indicates which variable is X_i created | |
| 587 from. The following example shows how the algorithm proceeds at a | |
| 588 high level: | |
| 589 | |
| 590 1 a_24 = x_1 | |
| 591 2 a_2 = PHI <a_24, x_1> | |
| 592 3 a_5 = PHI <a_2> | |
| 593 4 x_1 = PHI <x_298, a_5, a_2> | |
| 594 | |
| 595 The end result should be that a_2, a_5, a_24 and x_1 are a copy of | |
| 596 x_298. Propagation proceeds as follows. | |
| 597 | |
| 598 Visit #1: a_24 is copy-of x_1. Value changed. | |
| 599 Visit #2: a_2 is copy-of x_1. Value changed. | |
| 600 Visit #3: a_5 is copy-of x_1. Value changed. | |
| 601 Visit #4: x_1 is copy-of x_298. Value changed. | |
| 602 Visit #1: a_24 is copy-of x_298. Value changed. | |
| 603 Visit #2: a_2 is copy-of x_298. Value changed. | |
| 604 Visit #3: a_5 is copy-of x_298. Value changed. | |
| 605 Visit #4: x_1 is copy-of x_298. Stable state reached. | |
|
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606 |
| 0 | 607 When visiting PHI nodes, we only consider arguments that flow |
| 608 through edges marked executable by the propagation engine. So, | |
| 609 when visiting statement #2 for the first time, we will only look at | |
| 610 the first argument (a_24) and optimistically assume that its value | |
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611 is the copy of a_24 (x_1). */ |
| 0 | 612 |
| 613 static unsigned int | |
| 614 execute_copy_prop (void) | |
| 615 { | |
| 616 init_copy_prop (); | |
| 131 | 617 class copy_prop copy_prop; |
| 618 copy_prop.ssa_propagate (); | |
| 111 | 619 if (fini_copy_prop ()) |
| 620 return TODO_cleanup_cfg; | |
| 0 | 621 return 0; |
| 622 } | |
| 623 | |
| 111 | 624 namespace { |
| 625 | |
| 626 const pass_data pass_data_copy_prop = | |
| 0 | 627 { |
| 111 | 628 GIMPLE_PASS, /* type */ |
| 629 "copyprop", /* name */ | |
| 630 OPTGROUP_NONE, /* optinfo_flags */ | |
| 631 TV_TREE_COPY_PROP, /* tv_id */ | |
| 632 ( PROP_ssa | PROP_cfg ), /* properties_required */ | |
| 633 0, /* properties_provided */ | |
| 634 0, /* properties_destroyed */ | |
| 635 0, /* todo_flags_start */ | |
| 636 0, /* todo_flags_finish */ | |
| 637 }; | |
| 0 | 638 |
| 111 | 639 class pass_copy_prop : public gimple_opt_pass |
| 0 | 640 { |
| 111 | 641 public: |
| 642 pass_copy_prop (gcc::context *ctxt) | |
| 643 : gimple_opt_pass (pass_data_copy_prop, ctxt) | |
| 644 {} | |
| 645 | |
| 646 /* opt_pass methods: */ | |
| 647 opt_pass * clone () { return new pass_copy_prop (m_ctxt); } | |
| 648 virtual bool gate (function *) { return flag_tree_copy_prop != 0; } | |
| 649 virtual unsigned int execute (function *) { return execute_copy_prop (); } | |
| 650 | |
| 651 }; // class pass_copy_prop | |
| 652 | |
| 653 } // anon namespace | |
| 654 | |
| 655 gimple_opt_pass * | |
| 656 make_pass_copy_prop (gcc::context *ctxt) | |
| 657 { | |
| 658 return new pass_copy_prop (ctxt); | |
| 659 } |