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annotate gcc/tree-ssa-ter.c @ 63:b7f97abdc517 gcc-4.6-20100522
update gcc from gcc-4.5.0 to gcc-4.6
| author | ryoma <e075725@ie.u-ryukyu.ac.jp> |
|---|---|
| date | Mon, 24 May 2010 12:47:05 +0900 |
| parents | 77e2b8dfacca |
| children | f6334be47118 |
| rev | line source |
|---|---|
| 0 | 1 /* Routines for performing Temporary Expression Replacement (TER) in SSA trees. |
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2 Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010 |
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3 Free Software Foundation, Inc. |
| 0 | 4 Contributed by Andrew MacLeod <amacleod@redhat.com> |
| 5 | |
| 6 This file is part of GCC. | |
| 7 | |
| 8 GCC is free software; you can redistribute it and/or modify | |
| 9 it under the terms of the GNU General Public License as published by | |
| 10 the Free Software Foundation; either version 3, or (at your option) | |
| 11 any later version. | |
| 12 | |
| 13 GCC is distributed in the hope that it will be useful, | |
| 14 but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
| 16 GNU General Public License for more details. | |
| 17 | |
| 18 You should have received a copy of the GNU General Public License | |
| 19 along with GCC; see the file COPYING3. If not see | |
| 20 <http://www.gnu.org/licenses/>. */ | |
| 21 | |
| 22 | |
| 23 #include "config.h" | |
| 24 #include "system.h" | |
| 25 #include "coretypes.h" | |
| 26 #include "tm.h" | |
| 27 #include "tree.h" | |
| 28 #include "diagnostic.h" | |
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29 #include "tree-pretty-print.h" |
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30 #include "gimple-pretty-print.h" |
| 0 | 31 #include "bitmap.h" |
| 32 #include "tree-flow.h" | |
| 33 #include "tree-dump.h" | |
| 34 #include "tree-ssa-live.h" | |
| 35 #include "flags.h" | |
| 36 | |
| 37 | |
| 38 /* Temporary Expression Replacement (TER) | |
| 39 | |
| 40 Replace SSA version variables during out-of-ssa with their defining | |
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41 expression if there is only one use of the variable. |
| 0 | 42 |
| 43 This pass is required in order for the RTL expansion pass to see larger | |
| 44 chunks of code. This allows it to make better choices on RTL pattern | |
| 45 selection. When expand is rewritten and merged with out-of-ssa, and | |
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46 understands SSA, this should be eliminated. |
| 0 | 47 |
| 48 A pass is made through the function, one block at a time. No cross block | |
| 49 information is tracked. | |
| 50 | |
| 51 Variables which only have one use, and whose defining stmt is considered | |
| 52 a replaceable expression (see is_replaceable_p) are tracked to see whether | |
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53 they can be replaced at their use location. |
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54 |
| 0 | 55 n_12 = C * 10 |
| 56 a_2 = b_5 + 6 | |
| 57 v_9 = a_2 * n_12 | |
| 58 | |
| 59 if there are the only use of n_12 and a_2, TER will substitute in their | |
| 60 expressions in v_9, and end up with: | |
| 61 | |
| 62 v_9 = (b_5 + 6) * (C * 10) | |
| 63 | |
| 64 which will then have the ssa_name assigned to regular variables, and the | |
| 65 resulting code which will be passed to the expander looks something like: | |
| 66 | |
| 67 v = (b + 6) * (C * 10) | |
| 68 | |
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69 |
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70 This requires ensuring that none of the variables used by the expression |
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71 change between the def point and where it is used. Furthermore, if any |
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72 of the ssa_names used in this expression are themselves replaceable, we |
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73 have to ensure none of that expressions' arguments change either. |
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74 Although SSA_NAMES themselves don't change, this pass is performed after |
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75 coalescing has coalesced different SSA_NAMES together, so there could be a |
| 0 | 76 definition of an SSA_NAME which is coalesced with a use that causes a |
| 77 problem, i.e., | |
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78 |
| 0 | 79 PHI b_5 = <b_8(2), b_14(1)> |
| 80 <...> | |
| 81 a_2 = b_5 + 6 | |
| 82 b_8 = c_4 + 4 | |
| 83 v_9 = a_2 * n_12 | |
| 84 <...> | |
| 85 | |
| 86 If b_5, b_8 and b_14 are all coalesced together... | |
| 87 The expression b_5 + 6 CANNOT replace the use in the statement defining v_9 | |
| 88 because b_8 is in fact killing the value of b_5 since they share a partition | |
| 89 and will be assigned the same memory or register location. | |
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90 |
| 0 | 91 TER implements this but stepping through the instructions in a block and |
| 92 tracking potential expressions for replacement, and the partitions they are | |
| 93 dependent on. Expressions are represented by the SSA_NAME_VERSION of the | |
| 94 DEF on the LHS of a GIMPLE_ASSIGN and the expression is the RHS. | |
| 95 | |
| 96 When a stmt is determined to be a possible replacement expression, the | |
| 97 following steps are taken: | |
| 98 | |
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99 EXPR_DECL_UID bitmap is allocated and set to the base variable UID of the |
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100 def and any uses in the expression. non-NULL means the expression is being |
| 0 | 101 tracked. The UID's themselves are used to prevent TER substitution into |
| 102 accumulating sequences, i.e., | |
| 103 | |
| 104 x = x + y | |
| 105 x = x + z | |
| 106 x = x + w | |
| 107 etc. | |
| 108 this can result in very large expressions which don't accomplish anything | |
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109 see PR tree-optimization/17549. |
| 0 | 110 |
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111 PARTITION_DEPENDENCIES is another bitmap array, and it has a bit set for any |
| 0 | 112 partition which is used in the expression. This is primarily used to remove |
| 113 an expression from the partition kill lists when a decision is made whether | |
| 114 to replace it or not. This is indexed by ssa version number as well, and | |
| 115 indicates a partition number. virtual operands are not tracked individually, | |
| 116 but they are summarized by an artificial partition called VIRTUAL_PARTITION. | |
| 117 This means a MAY or MUST def will kill *ALL* expressions that are dependent | |
| 118 on a virtual operand. | |
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119 Note that the EXPR_DECL_UID and this bitmap represent very similar |
| 0 | 120 information, but the info in one is not easy to obtain from the other. |
| 121 | |
| 122 KILL_LIST is yet another bitmap array, this time it is indexed by partition | |
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123 number, and represents a list of active expressions which will will no |
| 0 | 124 longer be valid if a definition into this partition takes place. |
| 125 | |
| 126 PARTITION_IN_USE is simply a bitmap which is used to track which partitions | |
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127 currently have something in their kill list. This is used at the end of |
| 0 | 128 a block to clear out the KILL_LIST bitmaps at the end of each block. |
| 129 | |
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130 NEW_REPLACEABLE_DEPENDENCIES is used as a temporary place to store |
| 0 | 131 dependencies which will be reused by the current definition. All the uses |
| 132 on an expression are processed before anything else is done. If a use is | |
| 133 determined to be a replaceable expression AND the current stmt is also going | |
| 134 to be replaceable, all the dependencies of this replaceable use will be | |
| 135 picked up by the current stmt's expression. Rather than recreate them, they | |
| 136 are simply copied here and then copied into the new expression when it is | |
| 137 processed. | |
| 138 | |
| 139 a_2 = b_5 + 6 | |
| 140 v_8 = a_2 + c_4 | |
| 141 | |
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142 a_2's expression 'b_5 + 6' is determined to be replaceable at the use |
| 0 | 143 location. It is dependent on the partition 'b_5' is in. This is cached into |
| 144 the NEW_REPLACEABLE_DEPENDENCIES bitmap, and when v_8 is examined for | |
| 145 replaceability, it is a candidate, and it is dependent on the partition | |
| 146 b_5 is in *NOT* a_2, as well as c_4's partition. | |
| 147 | |
| 148 if v_8 is also replaceable: | |
| 149 | |
| 150 x_9 = v_8 * 5 | |
| 151 | |
| 152 x_9 is dependent on partitions b_5, and c_4 | |
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153 |
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154 if a statement is found which has either of those partitions written to |
| 0 | 155 before x_9 is used, then x_9 itself is NOT replaceable. */ |
| 156 | |
| 157 | |
| 158 /* Temporary Expression Replacement (TER) table information. */ | |
| 159 | |
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160 typedef struct temp_expr_table_d |
| 0 | 161 { |
| 162 var_map map; | |
| 163 bitmap *partition_dependencies; /* Partitions expr is dependent on. */ | |
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164 bitmap replaceable_expressions; /* Replacement expression table. */ |
| 0 | 165 bitmap *expr_decl_uids; /* Base uids of exprs. */ |
| 166 bitmap *kill_list; /* Expr's killed by a partition. */ | |
| 167 int virtual_partition; /* Pseudo partition for virtual ops. */ | |
| 168 bitmap partition_in_use; /* Partitions with kill entries. */ | |
| 169 bitmap new_replaceable_dependencies; /* Holding place for pending dep's. */ | |
| 170 int *num_in_part; /* # of ssa_names in a partition. */ | |
| 171 } *temp_expr_table_p; | |
| 172 | |
| 173 /* Used to indicate a dependency on VDEFs. */ | |
| 174 #define VIRTUAL_PARTITION(table) (table->virtual_partition) | |
| 175 | |
| 176 #ifdef ENABLE_CHECKING | |
| 177 extern void debug_ter (FILE *, temp_expr_table_p); | |
| 178 #endif | |
| 179 | |
| 180 | |
| 181 /* Create a new TER table for MAP. */ | |
| 182 | |
| 183 static temp_expr_table_p | |
| 184 new_temp_expr_table (var_map map) | |
| 185 { | |
| 186 temp_expr_table_p t; | |
| 187 unsigned x; | |
| 188 | |
| 189 t = XNEW (struct temp_expr_table_d); | |
| 190 t->map = map; | |
| 191 | |
| 192 t->partition_dependencies = XCNEWVEC (bitmap, num_ssa_names + 1); | |
| 193 t->expr_decl_uids = XCNEWVEC (bitmap, num_ssa_names + 1); | |
| 194 t->kill_list = XCNEWVEC (bitmap, num_var_partitions (map) + 1); | |
| 195 | |
| 196 t->partition_in_use = BITMAP_ALLOC (NULL); | |
| 197 | |
| 198 t->virtual_partition = num_var_partitions (map); | |
| 199 t->new_replaceable_dependencies = BITMAP_ALLOC (NULL); | |
| 200 | |
| 201 t->replaceable_expressions = NULL; | |
| 202 t->num_in_part = XCNEWVEC (int, num_var_partitions (map)); | |
| 203 for (x = 1; x < num_ssa_names; x++) | |
| 204 { | |
| 205 int p; | |
| 206 tree name = ssa_name (x); | |
| 207 if (!name) | |
| 208 continue; | |
| 209 p = var_to_partition (map, name); | |
| 210 if (p != NO_PARTITION) | |
| 211 t->num_in_part[p]++; | |
| 212 } | |
| 213 | |
| 214 return t; | |
| 215 } | |
| 216 | |
| 217 | |
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218 /* Free TER table T. If there are valid replacements, return the expression |
| 0 | 219 vector. */ |
| 220 | |
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221 static bitmap |
| 0 | 222 free_temp_expr_table (temp_expr_table_p t) |
| 223 { | |
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224 bitmap ret = NULL; |
| 0 | 225 |
| 226 #ifdef ENABLE_CHECKING | |
| 227 unsigned x; | |
| 228 for (x = 0; x <= num_var_partitions (t->map); x++) | |
| 229 gcc_assert (!t->kill_list[x]); | |
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230 for (x = 0; x < num_ssa_names; x++) |
| 0 | 231 { |
| 232 gcc_assert (t->expr_decl_uids[x] == NULL); | |
| 233 gcc_assert (t->partition_dependencies[x] == NULL); | |
| 234 } | |
| 235 #endif | |
| 236 | |
| 237 BITMAP_FREE (t->partition_in_use); | |
| 238 BITMAP_FREE (t->new_replaceable_dependencies); | |
| 239 | |
| 240 free (t->expr_decl_uids); | |
| 241 free (t->kill_list); | |
| 242 free (t->partition_dependencies); | |
| 243 free (t->num_in_part); | |
| 244 | |
| 245 if (t->replaceable_expressions) | |
| 246 ret = t->replaceable_expressions; | |
| 247 | |
| 248 free (t); | |
| 249 return ret; | |
| 250 } | |
| 251 | |
| 252 | |
| 253 /* Return TRUE if VERSION is to be replaced by an expression in TAB. */ | |
| 254 | |
| 255 static inline bool | |
| 256 version_to_be_replaced_p (temp_expr_table_p tab, int version) | |
| 257 { | |
| 258 if (!tab->replaceable_expressions) | |
| 259 return false; | |
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260 return bitmap_bit_p (tab->replaceable_expressions, version); |
| 0 | 261 } |
| 262 | |
| 263 | |
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264 /* Add partition P to the list if partitions VERSION is dependent on. TAB is |
| 0 | 265 the expression table */ |
| 266 | |
| 267 static inline void | |
| 268 make_dependent_on_partition (temp_expr_table_p tab, int version, int p) | |
| 269 { | |
| 270 if (!tab->partition_dependencies[version]) | |
| 271 tab->partition_dependencies[version] = BITMAP_ALLOC (NULL); | |
| 272 | |
| 273 bitmap_set_bit (tab->partition_dependencies[version], p); | |
| 274 } | |
| 275 | |
| 276 | |
| 277 /* Add VER to the kill list for P. TAB is the expression table */ | |
| 278 | |
| 279 static inline void | |
| 280 add_to_partition_kill_list (temp_expr_table_p tab, int p, int ver) | |
| 281 { | |
| 282 if (!tab->kill_list[p]) | |
| 283 { | |
| 284 tab->kill_list[p] = BITMAP_ALLOC (NULL); | |
| 285 bitmap_set_bit (tab->partition_in_use, p); | |
| 286 } | |
| 287 bitmap_set_bit (tab->kill_list[p], ver); | |
| 288 } | |
| 289 | |
| 290 | |
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291 /* Remove VER from the partition kill list for P. TAB is the expression |
| 0 | 292 table. */ |
| 293 | |
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294 static inline void |
| 0 | 295 remove_from_partition_kill_list (temp_expr_table_p tab, int p, int version) |
| 296 { | |
| 297 #ifdef ENABLE_CHECKING | |
| 298 gcc_assert (tab->kill_list[p]); | |
| 299 #endif | |
| 300 bitmap_clear_bit (tab->kill_list[p], version); | |
| 301 if (bitmap_empty_p (tab->kill_list[p])) | |
| 302 { | |
| 303 bitmap_clear_bit (tab->partition_in_use, p); | |
| 304 BITMAP_FREE (tab->kill_list[p]); | |
| 305 } | |
| 306 } | |
| 307 | |
| 308 | |
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309 /* Add a dependency between the def of ssa VERSION and VAR. If VAR is |
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310 replaceable by an expression, add a dependence each of the elements of the |
| 0 | 311 expression. These are contained in the new_replaceable list. TAB is the |
| 312 expression table. */ | |
| 313 | |
| 314 static void | |
| 315 add_dependence (temp_expr_table_p tab, int version, tree var) | |
| 316 { | |
| 317 int i; | |
| 318 bitmap_iterator bi; | |
| 319 unsigned x; | |
| 320 | |
| 321 i = SSA_NAME_VERSION (var); | |
| 322 if (version_to_be_replaced_p (tab, i)) | |
| 323 { | |
| 324 if (!bitmap_empty_p (tab->new_replaceable_dependencies)) | |
| 325 { | |
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326 /* Version will now be killed by a write to any partition the |
| 0 | 327 substituted expression would have been killed by. */ |
| 328 EXECUTE_IF_SET_IN_BITMAP (tab->new_replaceable_dependencies, 0, x, bi) | |
| 329 add_to_partition_kill_list (tab, x, version); | |
| 330 | |
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331 /* Rather than set partition_dependencies and in_use lists bit by |
| 0 | 332 bit, simply OR in the new_replaceable_dependencies bits. */ |
| 333 if (!tab->partition_dependencies[version]) | |
| 334 tab->partition_dependencies[version] = BITMAP_ALLOC (NULL); | |
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335 bitmap_ior_into (tab->partition_dependencies[version], |
| 0 | 336 tab->new_replaceable_dependencies); |
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337 bitmap_ior_into (tab->partition_in_use, |
| 0 | 338 tab->new_replaceable_dependencies); |
| 339 /* It is only necessary to add these once. */ | |
| 340 bitmap_clear (tab->new_replaceable_dependencies); | |
| 341 } | |
| 342 } | |
| 343 else | |
| 344 { | |
| 345 i = var_to_partition (tab->map, var); | |
| 346 #ifdef ENABLE_CHECKING | |
| 347 gcc_assert (i != NO_PARTITION); | |
| 348 gcc_assert (tab->num_in_part[i] != 0); | |
| 349 #endif | |
| 350 /* Only dependencies on ssa_names which are coalesced with something need | |
| 351 to be tracked. Partitions with containing only a single SSA_NAME | |
| 352 *cannot* have their value changed. */ | |
| 353 if (tab->num_in_part[i] > 1) | |
| 354 { | |
| 355 add_to_partition_kill_list (tab, i, version); | |
| 356 make_dependent_on_partition (tab, version, i); | |
| 357 } | |
| 358 } | |
| 359 } | |
| 360 | |
| 361 | |
| 362 /* Return TRUE if expression STMT is suitable for replacement. */ | |
| 363 | |
| 364 static inline bool | |
| 365 is_replaceable_p (gimple stmt) | |
| 366 { | |
| 367 use_operand_p use_p; | |
| 368 tree def; | |
| 369 gimple use_stmt; | |
| 370 location_t locus1, locus2; | |
| 371 tree block1, block2; | |
| 372 | |
| 373 /* Only consider modify stmts. */ | |
| 374 if (!is_gimple_assign (stmt)) | |
| 375 return false; | |
| 376 | |
| 377 /* If the statement may throw an exception, it cannot be replaced. */ | |
| 378 if (stmt_could_throw_p (stmt)) | |
| 379 return false; | |
| 380 | |
| 381 /* Punt if there is more than 1 def. */ | |
| 382 def = SINGLE_SSA_TREE_OPERAND (stmt, SSA_OP_DEF); | |
| 383 if (!def) | |
| 384 return false; | |
| 385 | |
| 386 /* Only consider definitions which have a single use. */ | |
| 387 if (!single_imm_use (def, &use_p, &use_stmt)) | |
| 388 return false; | |
| 389 | |
| 390 /* If the use isn't in this block, it wont be replaced either. */ | |
| 391 if (gimple_bb (use_stmt) != gimple_bb (stmt)) | |
| 392 return false; | |
| 393 | |
| 394 locus1 = gimple_location (stmt); | |
| 395 block1 = gimple_block (stmt); | |
| 396 | |
| 397 if (gimple_code (use_stmt) == GIMPLE_PHI) | |
| 398 { | |
| 399 locus2 = 0; | |
| 400 block2 = NULL_TREE; | |
| 401 } | |
| 402 else | |
| 403 { | |
| 404 locus2 = gimple_location (use_stmt); | |
| 405 block2 = gimple_block (use_stmt); | |
| 406 } | |
| 407 | |
| 408 if (!optimize | |
| 409 && ((locus1 && locus1 != locus2) || (block1 && block1 != block2))) | |
| 410 return false; | |
| 411 | |
| 412 /* Used in this block, but at the TOP of the block, not the end. */ | |
| 413 if (gimple_code (use_stmt) == GIMPLE_PHI) | |
| 414 return false; | |
| 415 | |
| 416 /* There must be no VDEFs. */ | |
|
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417 if (gimple_vdef (stmt)) |
| 0 | 418 return false; |
| 419 | |
| 420 /* Without alias info we can't move around loads. */ | |
| 421 if (gimple_references_memory_p (stmt) && !optimize) | |
| 422 return false; | |
| 423 | |
| 424 /* Float expressions must go through memory if float-store is on. */ | |
|
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425 if (flag_float_store |
| 0 | 426 && FLOAT_TYPE_P (gimple_expr_type (stmt))) |
| 427 return false; | |
| 428 | |
| 429 /* An assignment with a register variable on the RHS is not | |
| 430 replaceable. */ | |
| 431 if (gimple_assign_rhs_code (stmt) == VAR_DECL | |
| 432 && DECL_HARD_REGISTER (gimple_assign_rhs1 (stmt))) | |
| 433 return false; | |
| 434 | |
| 435 /* No function calls can be replaced. */ | |
| 436 if (is_gimple_call (stmt)) | |
| 437 return false; | |
| 438 | |
| 439 /* Leave any stmt with volatile operands alone as well. */ | |
| 440 if (gimple_has_volatile_ops (stmt)) | |
| 441 return false; | |
| 442 | |
| 443 return true; | |
| 444 } | |
| 445 | |
| 446 | |
|
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447 /* This function will remove the expression for VERSION from replacement |
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448 consideration in table TAB. If FREE_EXPR is true, then remove the |
| 0 | 449 expression from consideration as well by freeing the decl uid bitmap. */ |
| 450 | |
| 451 static void | |
| 452 finished_with_expr (temp_expr_table_p tab, int version, bool free_expr) | |
| 453 { | |
| 454 unsigned i; | |
| 455 bitmap_iterator bi; | |
| 456 | |
| 457 /* Remove this expression from its dependent lists. The partition dependence | |
| 458 list is retained and transfered later to whomever uses this version. */ | |
| 459 if (tab->partition_dependencies[version]) | |
| 460 { | |
| 461 EXECUTE_IF_SET_IN_BITMAP (tab->partition_dependencies[version], 0, i, bi) | |
| 462 remove_from_partition_kill_list (tab, i, version); | |
| 463 BITMAP_FREE (tab->partition_dependencies[version]); | |
| 464 } | |
| 465 if (free_expr) | |
| 466 BITMAP_FREE (tab->expr_decl_uids[version]); | |
| 467 } | |
| 468 | |
| 469 | |
| 470 /* Create an expression entry for a replaceable expression. */ | |
| 471 | |
|
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472 static void |
| 0 | 473 process_replaceable (temp_expr_table_p tab, gimple stmt) |
| 474 { | |
| 475 tree var, def, basevar; | |
| 476 int version; | |
| 477 ssa_op_iter iter; | |
| 478 bitmap def_vars, use_vars; | |
| 479 | |
| 480 #ifdef ENABLE_CHECKING | |
| 481 gcc_assert (is_replaceable_p (stmt)); | |
| 482 #endif | |
| 483 | |
| 484 def = SINGLE_SSA_TREE_OPERAND (stmt, SSA_OP_DEF); | |
| 485 version = SSA_NAME_VERSION (def); | |
| 486 basevar = SSA_NAME_VAR (def); | |
| 487 def_vars = BITMAP_ALLOC (NULL); | |
| 488 | |
| 489 bitmap_set_bit (def_vars, DECL_UID (basevar)); | |
| 490 | |
| 491 /* Add this expression to the dependency list for each use partition. */ | |
| 492 FOR_EACH_SSA_TREE_OPERAND (var, stmt, iter, SSA_OP_USE) | |
| 493 { | |
| 494 int var_version = SSA_NAME_VERSION (var); | |
| 495 | |
| 496 use_vars = tab->expr_decl_uids[var_version]; | |
| 497 add_dependence (tab, version, var); | |
| 498 if (use_vars) | |
| 499 { | |
| 500 bitmap_ior_into (def_vars, use_vars); | |
| 501 BITMAP_FREE (tab->expr_decl_uids[var_version]); | |
| 502 } | |
| 503 else | |
| 504 bitmap_set_bit (def_vars, DECL_UID (SSA_NAME_VAR (var))); | |
| 505 } | |
| 506 tab->expr_decl_uids[version] = def_vars; | |
| 507 | |
| 508 /* If there are VUSES, add a dependence on virtual defs. */ | |
|
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509 if (gimple_vuse (stmt)) |
| 0 | 510 { |
| 511 make_dependent_on_partition (tab, version, VIRTUAL_PARTITION (tab)); | |
| 512 add_to_partition_kill_list (tab, VIRTUAL_PARTITION (tab), version); | |
| 513 } | |
| 514 } | |
| 515 | |
| 516 | |
| 517 /* This function removes any expression in TAB which is dependent on PARTITION | |
| 518 from consideration, making it not replaceable. */ | |
| 519 | |
| 520 static inline void | |
| 521 kill_expr (temp_expr_table_p tab, int partition) | |
| 522 { | |
| 523 unsigned version; | |
| 524 | |
|
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525 /* Mark every active expr dependent on this var as not replaceable. |
| 0 | 526 finished_with_expr can modify the bitmap, so we can't execute over it. */ |
| 527 while (tab->kill_list[partition]) | |
| 528 { | |
| 529 version = bitmap_first_set_bit (tab->kill_list[partition]); | |
| 530 finished_with_expr (tab, version, true); | |
| 531 } | |
| 532 | |
| 533 #ifdef ENABLE_CHECKING | |
| 534 gcc_assert (!tab->kill_list[partition]); | |
| 535 #endif | |
| 536 } | |
| 537 | |
| 538 | |
|
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539 /* This function kills all expressions in TAB which are dependent on virtual |
| 0 | 540 partitions. */ |
| 541 | |
| 542 static inline void | |
| 543 kill_virtual_exprs (temp_expr_table_p tab) | |
| 544 { | |
| 545 kill_expr (tab, VIRTUAL_PARTITION (tab)); | |
| 546 } | |
| 547 | |
| 548 | |
| 549 /* Mark the expression associated with VAR as replaceable, and enter | |
| 550 the defining stmt into the partition_dependencies table TAB. If | |
| 551 MORE_REPLACING is true, accumulate the pending partition dependencies. */ | |
| 552 | |
| 553 static void | |
| 554 mark_replaceable (temp_expr_table_p tab, tree var, bool more_replacing) | |
| 555 { | |
| 556 int version = SSA_NAME_VERSION (var); | |
| 557 | |
| 558 /* Move the dependence list to the pending listpending. */ | |
| 559 if (more_replacing && tab->partition_dependencies[version]) | |
|
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560 bitmap_ior_into (tab->new_replaceable_dependencies, |
| 0 | 561 tab->partition_dependencies[version]); |
| 562 | |
| 563 finished_with_expr (tab, version, !more_replacing); | |
| 564 | |
| 565 /* Set the replaceable expression. */ | |
| 566 if (!tab->replaceable_expressions) | |
|
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567 tab->replaceable_expressions = BITMAP_ALLOC (NULL); |
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568 bitmap_set_bit (tab->replaceable_expressions, version); |
| 0 | 569 } |
| 570 | |
| 571 | |
| 572 /* This function processes basic block BB, and looks for variables which can | |
| 573 be replaced by their expressions. Results are stored in the table TAB. */ | |
| 574 | |
| 575 static void | |
| 576 find_replaceable_in_bb (temp_expr_table_p tab, basic_block bb) | |
| 577 { | |
| 578 gimple_stmt_iterator bsi; | |
| 579 gimple stmt; | |
| 580 tree def, use; | |
| 581 int partition; | |
| 582 var_map map = tab->map; | |
| 583 ssa_op_iter iter; | |
| 584 bool stmt_replaceable; | |
| 585 | |
| 586 for (bsi = gsi_start_bb (bb); !gsi_end_p (bsi); gsi_next (&bsi)) | |
| 587 { | |
| 588 stmt = gsi_stmt (bsi); | |
| 589 | |
|
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590 if (is_gimple_debug (stmt)) |
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591 continue; |
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592 |
| 0 | 593 stmt_replaceable = is_replaceable_p (stmt); |
| 594 | |
| 595 /* Determine if this stmt finishes an existing expression. */ | |
| 596 FOR_EACH_SSA_TREE_OPERAND (use, stmt, iter, SSA_OP_USE) | |
| 597 { | |
| 598 unsigned ver = SSA_NAME_VERSION (use); | |
| 599 | |
| 600 /* If this use is a potential replacement variable, process it. */ | |
| 601 if (tab->expr_decl_uids[ver]) | |
| 602 { | |
| 603 bool same_root_var = false; | |
| 604 ssa_op_iter iter2; | |
| 605 bitmap vars = tab->expr_decl_uids[ver]; | |
| 606 | |
| 607 /* See if the root variables are the same. If they are, we | |
| 608 do not want to do the replacement to avoid problems with | |
| 609 code size, see PR tree-optimization/17549. */ | |
| 610 if (!bitmap_empty_p (vars)) | |
| 611 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter2, SSA_OP_DEF) | |
| 612 { | |
| 613 if (bitmap_bit_p (vars, DECL_UID (SSA_NAME_VAR (def)))) | |
| 614 { | |
| 615 same_root_var = true; | |
| 616 break; | |
| 617 } | |
| 618 } | |
| 619 | |
|
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620 /* Mark expression as replaceable unless stmt is volatile or the |
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621 def variable has the same root variable as something in the |
| 0 | 622 substitution list. */ |
| 623 if (gimple_has_volatile_ops (stmt) || same_root_var) | |
| 624 finished_with_expr (tab, ver, true); | |
| 625 else | |
| 626 mark_replaceable (tab, use, stmt_replaceable); | |
| 627 } | |
| 628 } | |
|
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629 |
| 0 | 630 /* Next, see if this stmt kills off an active expression. */ |
| 631 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF) | |
| 632 { | |
| 633 partition = var_to_partition (map, def); | |
| 634 if (partition != NO_PARTITION && tab->kill_list[partition]) | |
| 635 kill_expr (tab, partition); | |
| 636 } | |
| 637 | |
| 638 /* Now see if we are creating a new expression or not. */ | |
| 639 if (stmt_replaceable) | |
| 640 process_replaceable (tab, stmt); | |
| 641 | |
| 642 /* Free any unused dependency lists. */ | |
| 643 bitmap_clear (tab->new_replaceable_dependencies); | |
| 644 | |
| 645 /* A V_{MAY,MUST}_DEF kills any expression using a virtual operand, | |
| 646 including the current stmt. */ | |
|
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647 if (gimple_vdef (stmt)) |
| 0 | 648 kill_virtual_exprs (tab); |
| 649 } | |
| 650 } | |
| 651 | |
| 652 | |
| 653 /* This function is the driver routine for replacement of temporary expressions | |
|
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654 in the SSA->normal phase, operating on MAP. If there are replaceable |
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655 expressions, a table is returned which maps SSA versions to the |
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656 expressions they should be replaced with. A NULL_TREE indicates no |
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657 replacement should take place. If there are no replacements at all, |
| 0 | 658 NULL is returned by the function, otherwise an expression vector indexed |
| 659 by SSA_NAME version numbers. */ | |
| 660 | |
|
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661 extern bitmap |
| 0 | 662 find_replaceable_exprs (var_map map) |
| 663 { | |
| 664 basic_block bb; | |
| 665 temp_expr_table_p table; | |
|
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666 bitmap ret; |
| 0 | 667 |
| 668 table = new_temp_expr_table (map); | |
| 669 FOR_EACH_BB (bb) | |
| 670 { | |
| 671 find_replaceable_in_bb (table, bb); | |
| 672 #ifdef ENABLE_CHECKING | |
| 673 gcc_assert (bitmap_empty_p (table->partition_in_use)); | |
| 674 #endif | |
| 675 } | |
| 676 | |
| 677 ret = free_temp_expr_table (table); | |
| 678 return ret; | |
|
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679 } |
| 0 | 680 |
| 681 /* Dump TER expression table EXPR to file F. */ | |
| 682 | |
| 683 void | |
|
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684 dump_replaceable_exprs (FILE *f, bitmap expr) |
| 0 | 685 { |
| 686 tree var; | |
| 687 unsigned x; | |
| 688 | |
| 689 fprintf (f, "\nReplacing Expressions\n"); | |
| 690 for (x = 0; x < num_ssa_names; x++) | |
|
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691 if (bitmap_bit_p (expr, x)) |
| 0 | 692 { |
| 693 var = ssa_name (x); | |
| 694 print_generic_expr (f, var, TDF_SLIM); | |
| 695 fprintf (f, " replace with --> "); | |
|
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696 print_gimple_stmt (f, SSA_NAME_DEF_STMT (var), 0, TDF_SLIM); |
| 0 | 697 fprintf (f, "\n"); |
| 698 } | |
| 699 fprintf (f, "\n"); | |
| 700 } | |
| 701 | |
| 702 | |
| 703 #ifdef ENABLE_CHECKING | |
| 704 /* Dump the status of the various tables in the expression table. This is used | |
| 705 exclusively to debug TER. F is the place to send debug info and T is the | |
| 706 table being debugged. */ | |
| 707 | |
| 708 void | |
| 709 debug_ter (FILE *f, temp_expr_table_p t) | |
| 710 { | |
| 711 unsigned x, y; | |
| 712 bitmap_iterator bi; | |
| 713 | |
|
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714 fprintf (f, "\nDumping current state of TER\n virtual partition = %d\n", |
| 0 | 715 VIRTUAL_PARTITION (t)); |
| 716 if (t->replaceable_expressions) | |
| 717 dump_replaceable_exprs (f, t->replaceable_expressions); | |
| 718 fprintf (f, "Currently tracking the following expressions:\n"); | |
| 719 | |
| 720 for (x = 1; x < num_ssa_names; x++) | |
| 721 if (t->expr_decl_uids[x]) | |
| 722 { | |
| 723 print_generic_expr (stderr, ssa_name (x), TDF_SLIM); | |
| 724 fprintf (f, " dep-parts : "); | |
|
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725 if (t->partition_dependencies[x] |
| 0 | 726 && !bitmap_empty_p (t->partition_dependencies[x])) |
| 727 { | |
| 728 EXECUTE_IF_SET_IN_BITMAP (t->partition_dependencies[x], 0, y, bi) | |
| 729 fprintf (f, "P%d ",y); | |
| 730 } | |
| 731 fprintf (stderr, " basedecls: "); | |
| 732 EXECUTE_IF_SET_IN_BITMAP (t->expr_decl_uids[x], 0, y, bi) | |
| 733 fprintf (f, "%d ",y); | |
| 734 fprintf (stderr, "\n"); | |
| 735 } | |
| 736 | |
|
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737 bitmap_print (f, t->partition_in_use, "Partitions in use ", |
| 0 | 738 "\npartition KILL lists:\n"); |
| 739 | |
| 740 for (x = 0; x <= num_var_partitions (t->map); x++) | |
| 741 if (t->kill_list[x]) | |
| 742 { | |
| 743 fprintf (f, "Partition %d : ", x); | |
| 744 EXECUTE_IF_SET_IN_BITMAP (t->kill_list[x], 0, y, bi) | |
| 745 fprintf (f, "_%d ",y); | |
| 746 } | |
| 747 | |
| 748 fprintf (f, "\n----------\n"); | |
| 749 } | |
| 750 #endif |