Mercurial > hg > CbC > CbC_gcc
annotate gcc/tree-ssa-copy.c @ 127:4c56639505ff
fix function.c and add CbC-example Makefile
| author | mir3636 |
|---|---|
| date | Wed, 11 Apr 2018 18:46:58 +0900 |
| parents | 04ced10e8804 |
| children | 84e7813d76e9 |
| rev | line source |
|---|---|
| 0 | 1 /* Copy propagation and SSA_NAME replacement support routines. |
| 111 | 2 Copyright (C) 2004-2017 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 |
| 0 | 71 static prop_value_t *copy_of; |
| 111 | 72 static unsigned n_copy_of; |
| 0 | 73 |
| 74 | |
| 75 /* Return true if this statement may generate a useful copy. */ | |
| 76 | |
| 77 static bool | |
| 111 | 78 stmt_may_generate_copy (gimple *stmt) |
| 0 | 79 { |
| 80 if (gimple_code (stmt) == GIMPLE_PHI) | |
| 81 return !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (gimple_phi_result (stmt)); | |
| 82 | |
| 83 if (gimple_code (stmt) != GIMPLE_ASSIGN) | |
| 84 return false; | |
| 85 | |
| 86 /* If the statement has volatile operands, it won't generate a | |
| 87 useful copy. */ | |
| 88 if (gimple_has_volatile_ops (stmt)) | |
| 89 return false; | |
| 90 | |
| 91 /* Statements with loads and/or stores will never generate a useful copy. */ | |
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92 if (gimple_vuse (stmt)) |
| 0 | 93 return false; |
| 94 | |
| 95 /* Otherwise, the only statements that generate useful copies are | |
| 96 assignments whose RHS is just an SSA name that doesn't flow | |
| 97 through abnormal edges. */ | |
| 111 | 98 return ((gimple_assign_rhs_code (stmt) == SSA_NAME |
| 99 && !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (gimple_assign_rhs1 (stmt))) | |
| 100 || is_gimple_min_invariant (gimple_assign_rhs1 (stmt))); | |
| 0 | 101 } |
| 102 | |
| 103 | |
| 104 /* Return the copy-of value for VAR. */ | |
| 105 | |
| 106 static inline prop_value_t * | |
| 107 get_copy_of_val (tree var) | |
| 108 { | |
| 109 prop_value_t *val = ©_of[SSA_NAME_VERSION (var)]; | |
| 110 | |
| 111 if (val->value == NULL_TREE | |
| 112 && !stmt_may_generate_copy (SSA_NAME_DEF_STMT (var))) | |
| 113 { | |
| 114 /* If the variable will never generate a useful copy relation, | |
| 115 make it its own copy. */ | |
| 116 val->value = var; | |
| 117 } | |
| 118 | |
| 119 return val; | |
| 120 } | |
| 121 | |
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122 /* Return the variable VAR is a copy of or VAR if VAR isn't the result |
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123 of a copy. */ |
| 0 | 124 |
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125 static inline tree |
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126 valueize_val (tree var) |
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127 { |
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128 if (TREE_CODE (var) == SSA_NAME) |
| 0 | 129 { |
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130 tree val = get_copy_of_val (var)->value; |
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131 if (val) |
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132 return val; |
| 0 | 133 } |
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134 return var; |
| 0 | 135 } |
| 136 | |
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137 /* Set VAL to be the copy of VAR. If that changed return true. */ |
| 0 | 138 |
| 139 static inline bool | |
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140 set_copy_of_val (tree var, tree val) |
| 0 | 141 { |
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142 unsigned int ver = SSA_NAME_VERSION (var); |
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143 tree old; |
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144 |
| 0 | 145 /* Set FIRST to be the first link in COPY_OF[DEST]. If that |
| 146 changed, return true. */ | |
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147 old = copy_of[ver].value; |
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148 copy_of[ver].value = val; |
| 0 | 149 |
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150 if (old != val |
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151 || (val && !operand_equal_p (old, val, 0))) |
| 0 | 152 return true; |
| 153 | |
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154 return false; |
| 0 | 155 } |
| 156 | |
| 157 | |
| 158 /* Dump the copy-of value for variable VAR to FILE. */ | |
| 159 | |
| 160 static void | |
| 161 dump_copy_of (FILE *file, tree var) | |
| 162 { | |
| 163 tree val; | |
| 164 | |
| 165 print_generic_expr (file, var, dump_flags); | |
| 166 if (TREE_CODE (var) != SSA_NAME) | |
| 167 return; | |
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168 |
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169 val = copy_of[SSA_NAME_VERSION (var)].value; |
| 0 | 170 fprintf (file, " copy-of chain: "); |
| 111 | 171 print_generic_expr (file, var); |
| 0 | 172 fprintf (file, " "); |
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173 if (!val) |
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174 fprintf (file, "[UNDEFINED]"); |
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175 else if (val == var) |
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176 fprintf (file, "[NOT A COPY]"); |
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177 else |
| 0 | 178 { |
| 179 fprintf (file, "-> "); | |
| 111 | 180 print_generic_expr (file, val); |
| 0 | 181 fprintf (file, " "); |
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182 fprintf (file, "[COPY]"); |
| 0 | 183 } |
| 184 } | |
| 185 | |
| 186 | |
| 187 /* Evaluate the RHS of STMT. If it produces a valid copy, set the LHS | |
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188 value and store the LHS into *RESULT_P. */ |
| 0 | 189 |
| 190 static enum ssa_prop_result | |
| 111 | 191 copy_prop_visit_assignment (gimple *stmt, tree *result_p) |
| 0 | 192 { |
| 193 tree lhs, rhs; | |
| 194 | |
| 195 lhs = gimple_assign_lhs (stmt); | |
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196 rhs = valueize_val (gimple_assign_rhs1 (stmt)); |
| 0 | 197 |
| 198 if (TREE_CODE (lhs) == SSA_NAME) | |
| 199 { | |
| 200 /* Straight copy between two SSA names. First, make sure that | |
| 201 we can propagate the RHS into uses of LHS. */ | |
| 202 if (!may_propagate_copy (lhs, rhs)) | |
| 203 return SSA_PROP_VARYING; | |
| 204 | |
| 205 *result_p = lhs; | |
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206 if (set_copy_of_val (*result_p, rhs)) |
| 0 | 207 return SSA_PROP_INTERESTING; |
| 208 else | |
| 209 return SSA_PROP_NOT_INTERESTING; | |
| 210 } | |
| 211 | |
| 212 return SSA_PROP_VARYING; | |
| 213 } | |
| 214 | |
| 215 | |
| 216 /* Visit the GIMPLE_COND STMT. Return SSA_PROP_INTERESTING | |
| 217 if it can determine which edge will be taken. Otherwise, return | |
| 218 SSA_PROP_VARYING. */ | |
| 219 | |
| 220 static enum ssa_prop_result | |
| 111 | 221 copy_prop_visit_cond_stmt (gimple *stmt, edge *taken_edge_p) |
| 0 | 222 { |
| 223 enum ssa_prop_result retval = SSA_PROP_VARYING; | |
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224 location_t loc = gimple_location (stmt); |
| 0 | 225 |
| 111 | 226 tree op0 = valueize_val (gimple_cond_lhs (stmt)); |
| 227 tree op1 = valueize_val (gimple_cond_rhs (stmt)); | |
| 0 | 228 |
| 111 | 229 /* See if we can determine the predicate's value. */ |
| 230 if (dump_file && (dump_flags & TDF_DETAILS)) | |
| 231 { | |
| 232 fprintf (dump_file, "Trying to determine truth value of "); | |
| 233 fprintf (dump_file, "predicate "); | |
| 234 print_gimple_stmt (dump_file, stmt, 0); | |
| 235 } | |
| 0 | 236 |
| 111 | 237 /* Fold COND and see whether we get a useful result. */ |
| 238 tree folded_cond = fold_binary_loc (loc, gimple_cond_code (stmt), | |
| 239 boolean_type_node, op0, op1); | |
| 240 if (folded_cond) | |
| 241 { | |
| 242 basic_block bb = gimple_bb (stmt); | |
| 243 *taken_edge_p = find_taken_edge (bb, folded_cond); | |
| 244 if (*taken_edge_p) | |
| 245 retval = SSA_PROP_INTERESTING; | |
| 0 | 246 } |
| 247 | |
| 248 if (dump_file && (dump_flags & TDF_DETAILS) && *taken_edge_p) | |
| 249 fprintf (dump_file, "\nConditional will always take edge %d->%d\n", | |
| 250 (*taken_edge_p)->src->index, (*taken_edge_p)->dest->index); | |
| 251 | |
| 252 return retval; | |
| 253 } | |
| 254 | |
| 255 | |
| 256 /* Evaluate statement STMT. If the statement produces a new output | |
| 257 value, return SSA_PROP_INTERESTING and store the SSA_NAME holding | |
| 258 the new value in *RESULT_P. | |
| 259 | |
| 260 If STMT is a conditional branch and we can determine its truth | |
| 261 value, set *TAKEN_EDGE_P accordingly. | |
| 262 | |
| 263 If the new value produced by STMT is varying, return | |
| 264 SSA_PROP_VARYING. */ | |
| 265 | |
| 266 static enum ssa_prop_result | |
| 111 | 267 copy_prop_visit_stmt (gimple *stmt, edge *taken_edge_p, tree *result_p) |
| 0 | 268 { |
| 269 enum ssa_prop_result retval; | |
| 270 | |
| 271 if (dump_file && (dump_flags & TDF_DETAILS)) | |
| 272 { | |
| 273 fprintf (dump_file, "\nVisiting statement:\n"); | |
| 274 print_gimple_stmt (dump_file, stmt, 0, dump_flags); | |
| 275 fprintf (dump_file, "\n"); | |
| 276 } | |
| 277 | |
| 278 if (gimple_assign_single_p (stmt) | |
| 279 && TREE_CODE (gimple_assign_lhs (stmt)) == SSA_NAME | |
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280 && (TREE_CODE (gimple_assign_rhs1 (stmt)) == SSA_NAME |
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281 || is_gimple_min_invariant (gimple_assign_rhs1 (stmt)))) |
| 0 | 282 { |
| 283 /* If the statement is a copy assignment, evaluate its RHS to | |
| 284 see if the lattice value of its output has changed. */ | |
| 285 retval = copy_prop_visit_assignment (stmt, result_p); | |
| 286 } | |
| 287 else if (gimple_code (stmt) == GIMPLE_COND) | |
| 288 { | |
| 289 /* See if we can determine which edge goes out of a conditional | |
| 290 jump. */ | |
| 291 retval = copy_prop_visit_cond_stmt (stmt, taken_edge_p); | |
| 292 } | |
| 293 else | |
| 294 retval = SSA_PROP_VARYING; | |
| 295 | |
| 296 if (retval == SSA_PROP_VARYING) | |
| 297 { | |
| 298 tree def; | |
| 299 ssa_op_iter i; | |
| 300 | |
| 301 /* Any other kind of statement is not interesting for constant | |
| 302 propagation and, therefore, not worth simulating. */ | |
| 303 if (dump_file && (dump_flags & TDF_DETAILS)) | |
| 304 fprintf (dump_file, "No interesting values produced.\n"); | |
| 305 | |
| 306 /* The assignment is not a copy operation. Don't visit this | |
| 307 statement again and mark all the definitions in the statement | |
| 308 to be copies of nothing. */ | |
| 309 FOR_EACH_SSA_TREE_OPERAND (def, stmt, i, SSA_OP_ALL_DEFS) | |
| 310 set_copy_of_val (def, def); | |
| 311 } | |
| 312 | |
| 313 return retval; | |
| 314 } | |
| 315 | |
| 316 | |
| 317 /* Visit PHI node PHI. If all the arguments produce the same value, | |
| 318 set it to be the value of the LHS of PHI. */ | |
| 319 | |
| 320 static enum ssa_prop_result | |
| 111 | 321 copy_prop_visit_phi_node (gphi *phi) |
| 0 | 322 { |
| 323 enum ssa_prop_result retval; | |
| 324 unsigned i; | |
|
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325 prop_value_t phi_val = { NULL_TREE }; |
| 0 | 326 |
| 327 tree lhs = gimple_phi_result (phi); | |
| 328 | |
| 329 if (dump_file && (dump_flags & TDF_DETAILS)) | |
| 330 { | |
| 331 fprintf (dump_file, "\nVisiting PHI node: "); | |
| 332 print_gimple_stmt (dump_file, phi, 0, dump_flags); | |
| 333 } | |
| 334 | |
| 335 for (i = 0; i < gimple_phi_num_args (phi); i++) | |
| 336 { | |
| 337 prop_value_t *arg_val; | |
| 111 | 338 tree arg_value; |
| 0 | 339 tree arg = gimple_phi_arg_def (phi, i); |
| 340 edge e = gimple_phi_arg_edge (phi, i); | |
| 341 | |
| 342 /* We don't care about values flowing through non-executable | |
| 343 edges. */ | |
| 344 if (!(e->flags & EDGE_EXECUTABLE)) | |
| 345 continue; | |
| 346 | |
| 111 | 347 /* Names that flow through abnormal edges cannot be used to |
| 348 derive copies. */ | |
| 349 if (TREE_CODE (arg) == SSA_NAME && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (arg)) | |
| 0 | 350 { |
| 351 phi_val.value = lhs; | |
| 352 break; | |
| 353 } | |
| 354 | |
| 355 if (dump_file && (dump_flags & TDF_DETAILS)) | |
| 356 { | |
| 357 fprintf (dump_file, "\tArgument #%d: ", i); | |
| 358 dump_copy_of (dump_file, arg); | |
| 359 fprintf (dump_file, "\n"); | |
| 360 } | |
| 361 | |
| 111 | 362 if (TREE_CODE (arg) == SSA_NAME) |
| 363 { | |
| 364 arg_val = get_copy_of_val (arg); | |
| 365 | |
| 366 /* If we didn't visit the definition of arg yet treat it as | |
| 367 UNDEFINED. This also handles PHI arguments that are the | |
| 368 same as lhs. We'll come here again. */ | |
| 369 if (!arg_val->value) | |
| 370 continue; | |
| 0 | 371 |
| 111 | 372 arg_value = arg_val->value; |
| 373 } | |
| 374 else | |
| 375 arg_value = valueize_val (arg); | |
| 376 | |
| 377 /* In loop-closed SSA form do not copy-propagate SSA-names across | |
| 378 loop exit edges. */ | |
| 379 if (loops_state_satisfies_p (LOOP_CLOSED_SSA) | |
| 380 && TREE_CODE (arg_value) == SSA_NAME | |
| 381 && loop_exit_edge_p (e->src->loop_father, e)) | |
| 382 { | |
| 383 phi_val.value = lhs; | |
| 384 break; | |
| 385 } | |
|
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386 |
| 0 | 387 /* If the LHS didn't have a value yet, make it a copy of the |
|
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388 first argument we find. */ |
| 0 | 389 if (phi_val.value == NULL_TREE) |
| 390 { | |
| 111 | 391 phi_val.value = arg_value; |
| 0 | 392 continue; |
| 393 } | |
| 394 | |
| 395 /* If PHI_VAL and ARG don't have a common copy-of chain, then | |
|
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396 this PHI node cannot be a copy operation. */ |
| 111 | 397 if (phi_val.value != arg_value |
| 398 && !operand_equal_p (phi_val.value, arg_value, 0)) | |
| 0 | 399 { |
| 400 phi_val.value = lhs; | |
| 401 break; | |
| 402 } | |
| 403 } | |
| 404 | |
|
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405 if (phi_val.value |
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406 && may_propagate_copy (lhs, phi_val.value) |
| 0 | 407 && set_copy_of_val (lhs, phi_val.value)) |
| 408 retval = (phi_val.value != lhs) ? SSA_PROP_INTERESTING : SSA_PROP_VARYING; | |
| 409 else | |
| 410 retval = SSA_PROP_NOT_INTERESTING; | |
| 411 | |
| 412 if (dump_file && (dump_flags & TDF_DETAILS)) | |
| 413 { | |
|
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414 fprintf (dump_file, "PHI node "); |
| 0 | 415 dump_copy_of (dump_file, lhs); |
| 416 fprintf (dump_file, "\nTelling the propagator to "); | |
| 417 if (retval == SSA_PROP_INTERESTING) | |
| 418 fprintf (dump_file, "add SSA edges out of this PHI and continue."); | |
| 419 else if (retval == SSA_PROP_VARYING) | |
| 420 fprintf (dump_file, "add SSA edges out of this PHI and never visit again."); | |
| 421 else | |
| 422 fprintf (dump_file, "do nothing with SSA edges and keep iterating."); | |
| 423 fprintf (dump_file, "\n\n"); | |
| 424 } | |
| 425 | |
| 426 return retval; | |
| 427 } | |
| 428 | |
| 429 | |
|
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430 /* Initialize structures used for copy propagation. */ |
| 0 | 431 |
| 432 static void | |
| 433 init_copy_prop (void) | |
| 434 { | |
| 435 basic_block bb; | |
| 436 | |
| 111 | 437 n_copy_of = num_ssa_names; |
| 438 copy_of = XCNEWVEC (prop_value_t, n_copy_of); | |
| 0 | 439 |
| 111 | 440 FOR_EACH_BB_FN (bb, cfun) |
| 0 | 441 { |
| 111 | 442 for (gimple_stmt_iterator si = gsi_start_bb (bb); !gsi_end_p (si); |
| 443 gsi_next (&si)) | |
| 0 | 444 { |
| 111 | 445 gimple *stmt = gsi_stmt (si); |
| 0 | 446 ssa_op_iter iter; |
| 447 tree def; | |
| 448 | |
| 449 /* The only statements that we care about are those that may | |
| 450 generate useful copies. We also need to mark conditional | |
| 451 jumps so that their outgoing edges are added to the work | |
| 111 | 452 lists of the propagator. */ |
| 0 | 453 if (stmt_ends_bb_p (stmt)) |
| 454 prop_set_simulate_again (stmt, true); | |
| 111 | 455 else if (stmt_may_generate_copy (stmt)) |
| 0 | 456 prop_set_simulate_again (stmt, true); |
| 457 else | |
| 458 prop_set_simulate_again (stmt, false); | |
| 459 | |
| 460 /* Mark all the outputs of this statement as not being | |
| 461 the copy of anything. */ | |
| 462 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS) | |
| 463 if (!prop_simulate_again_p (stmt)) | |
| 464 set_copy_of_val (def, def); | |
| 465 } | |
| 466 | |
| 111 | 467 for (gphi_iterator si = gsi_start_phis (bb); !gsi_end_p (si); |
| 468 gsi_next (&si)) | |
|
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469 { |
| 111 | 470 gphi *phi = si.phi (); |
| 0 | 471 tree def; |
| 472 | |
| 473 def = gimple_phi_result (phi); | |
| 111 | 474 if (virtual_operand_p (def)) |
| 0 | 475 prop_set_simulate_again (phi, false); |
| 476 else | |
| 477 prop_set_simulate_again (phi, true); | |
| 478 | |
| 479 if (!prop_simulate_again_p (phi)) | |
| 480 set_copy_of_val (def, def); | |
| 481 } | |
| 482 } | |
| 483 } | |
| 484 | |
|
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485 /* Callback for substitute_and_fold to get at the final copy-of values. */ |
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486 |
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487 static tree |
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488 get_value (tree name) |
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489 { |
| 111 | 490 tree val; |
| 491 if (SSA_NAME_VERSION (name) >= n_copy_of) | |
| 492 return NULL_TREE; | |
| 493 val = copy_of[SSA_NAME_VERSION (name)].value; | |
|
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494 if (val && val != name) |
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495 return val; |
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496 return NULL_TREE; |
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497 } |
| 0 | 498 |
| 499 /* Deallocate memory used in copy propagation and do final | |
| 500 substitution. */ | |
| 501 | |
| 111 | 502 static bool |
| 0 | 503 fini_copy_prop (void) |
| 504 { | |
|
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505 unsigned i; |
| 111 | 506 tree var; |
|
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507 |
| 0 | 508 /* Set the final copy-of value for each variable by traversing the |
| 509 copy-of chains. */ | |
| 111 | 510 FOR_EACH_SSA_NAME (i, var, cfun) |
| 0 | 511 { |
| 111 | 512 if (!copy_of[i].value |
|
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513 || copy_of[i].value == var) |
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514 continue; |
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515 |
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516 /* In theory the points-to solution of all members of the |
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517 copy chain is their intersection. For now we do not bother |
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518 to compute this but only make sure we do not lose points-to |
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519 information completely by setting the points-to solution |
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520 of the representative to the first solution we find if |
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521 it doesn't have one already. */ |
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522 if (copy_of[i].value != var |
| 111 | 523 && TREE_CODE (copy_of[i].value) == SSA_NAME) |
| 524 { | |
| 525 basic_block copy_of_bb | |
| 526 = gimple_bb (SSA_NAME_DEF_STMT (copy_of[i].value)); | |
| 527 basic_block var_bb = gimple_bb (SSA_NAME_DEF_STMT (var)); | |
| 528 if (POINTER_TYPE_P (TREE_TYPE (var)) | |
| 529 && SSA_NAME_PTR_INFO (var) | |
| 530 && !SSA_NAME_PTR_INFO (copy_of[i].value)) | |
| 531 { | |
| 532 duplicate_ssa_name_ptr_info (copy_of[i].value, | |
| 533 SSA_NAME_PTR_INFO (var)); | |
| 534 /* Points-to information is cfg insensitive, | |
| 535 but alignment info might be cfg sensitive, if it | |
| 536 e.g. is derived from VRP derived non-zero bits. | |
| 537 So, do not copy alignment info if the two SSA_NAMEs | |
| 538 aren't defined in the same basic block. */ | |
| 539 if (var_bb != copy_of_bb) | |
| 540 mark_ptr_info_alignment_unknown | |
| 541 (SSA_NAME_PTR_INFO (copy_of[i].value)); | |
| 542 } | |
| 543 else if (!POINTER_TYPE_P (TREE_TYPE (var)) | |
| 544 && SSA_NAME_RANGE_INFO (var) | |
| 545 && !SSA_NAME_RANGE_INFO (copy_of[i].value) | |
| 546 && var_bb == copy_of_bb) | |
| 547 duplicate_ssa_name_range_info (copy_of[i].value, | |
| 548 SSA_NAME_RANGE_TYPE (var), | |
| 549 SSA_NAME_RANGE_INFO (var)); | |
| 550 } | |
| 0 | 551 } |
| 552 | |
| 111 | 553 bool changed = substitute_and_fold (get_value, NULL); |
| 554 if (changed) | |
| 555 { | |
| 556 free_numbers_of_iterations_estimates (cfun); | |
| 557 if (scev_initialized_p ()) | |
| 558 scev_reset (); | |
| 559 } | |
| 0 | 560 |
| 561 free (copy_of); | |
| 111 | 562 |
| 563 return changed; | |
| 0 | 564 } |
| 565 | |
| 566 | |
| 567 /* Main entry point to the copy propagator. | |
| 568 | |
| 569 PHIS_ONLY is true if we should only consider PHI nodes as generating | |
|
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570 copy propagation opportunities. |
| 0 | 571 |
| 572 The algorithm propagates the value COPY-OF using ssa_propagate. For | |
| 573 every variable X_i, COPY-OF(X_i) indicates which variable is X_i created | |
| 574 from. The following example shows how the algorithm proceeds at a | |
| 575 high level: | |
| 576 | |
| 577 1 a_24 = x_1 | |
| 578 2 a_2 = PHI <a_24, x_1> | |
| 579 3 a_5 = PHI <a_2> | |
| 580 4 x_1 = PHI <x_298, a_5, a_2> | |
| 581 | |
| 582 The end result should be that a_2, a_5, a_24 and x_1 are a copy of | |
| 583 x_298. Propagation proceeds as follows. | |
| 584 | |
| 585 Visit #1: a_24 is copy-of x_1. Value changed. | |
| 586 Visit #2: a_2 is copy-of x_1. Value changed. | |
| 587 Visit #3: a_5 is copy-of x_1. Value changed. | |
| 588 Visit #4: x_1 is copy-of x_298. Value changed. | |
| 589 Visit #1: a_24 is copy-of x_298. Value changed. | |
| 590 Visit #2: a_2 is copy-of x_298. Value changed. | |
| 591 Visit #3: a_5 is copy-of x_298. Value changed. | |
| 592 Visit #4: x_1 is copy-of x_298. Stable state reached. | |
|
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593 |
| 0 | 594 When visiting PHI nodes, we only consider arguments that flow |
| 595 through edges marked executable by the propagation engine. So, | |
| 596 when visiting statement #2 for the first time, we will only look at | |
| 597 the first argument (a_24) and optimistically assume that its value | |
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598 is the copy of a_24 (x_1). */ |
| 0 | 599 |
| 600 static unsigned int | |
| 601 execute_copy_prop (void) | |
| 602 { | |
| 603 init_copy_prop (); | |
| 604 ssa_propagate (copy_prop_visit_stmt, copy_prop_visit_phi_node); | |
| 111 | 605 if (fini_copy_prop ()) |
| 606 return TODO_cleanup_cfg; | |
| 0 | 607 return 0; |
| 608 } | |
| 609 | |
| 111 | 610 namespace { |
| 611 | |
| 612 const pass_data pass_data_copy_prop = | |
| 0 | 613 { |
| 111 | 614 GIMPLE_PASS, /* type */ |
| 615 "copyprop", /* name */ | |
| 616 OPTGROUP_NONE, /* optinfo_flags */ | |
| 617 TV_TREE_COPY_PROP, /* tv_id */ | |
| 618 ( PROP_ssa | PROP_cfg ), /* properties_required */ | |
| 619 0, /* properties_provided */ | |
| 620 0, /* properties_destroyed */ | |
| 621 0, /* todo_flags_start */ | |
| 622 0, /* todo_flags_finish */ | |
| 623 }; | |
| 0 | 624 |
| 111 | 625 class pass_copy_prop : public gimple_opt_pass |
| 0 | 626 { |
| 111 | 627 public: |
| 628 pass_copy_prop (gcc::context *ctxt) | |
| 629 : gimple_opt_pass (pass_data_copy_prop, ctxt) | |
| 630 {} | |
| 631 | |
| 632 /* opt_pass methods: */ | |
| 633 opt_pass * clone () { return new pass_copy_prop (m_ctxt); } | |
| 634 virtual bool gate (function *) { return flag_tree_copy_prop != 0; } | |
| 635 virtual unsigned int execute (function *) { return execute_copy_prop (); } | |
| 636 | |
| 637 }; // class pass_copy_prop | |
| 638 | |
| 639 } // anon namespace | |
| 640 | |
| 641 gimple_opt_pass * | |
| 642 make_pass_copy_prop (gcc::context *ctxt) | |
| 643 { | |
| 644 return new pass_copy_prop (ctxt); | |
| 645 } |