Mercurial > hg > CbC > CbC_gcc
annotate gcc/tree-phinodes.c @ 67:f6334be47118
update gcc from gcc-4.6-20100522 to gcc-4.6-20110318
| author | nobuyasu <dimolto@cr.ie.u-ryukyu.ac.jp> |
|---|---|
| date | Tue, 22 Mar 2011 17:18:12 +0900 |
| parents | b7f97abdc517 |
| children | 04ced10e8804 |
| rev | line source |
|---|---|
| 0 | 1 /* Generic routines for manipulating PHIs |
|
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2 Copyright (C) 2003, 2005, 2007, 2008, 2009, 2010 |
|
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3 Free Software Foundation, Inc. |
| 0 | 4 |
| 5 This file is part of GCC. | |
| 6 | |
| 7 GCC is free software; you can redistribute it and/or modify | |
| 8 it under the terms of the GNU General Public License as published by | |
| 9 the Free Software Foundation; either version 3, or (at your option) | |
| 10 any later version. | |
| 11 | |
| 12 GCC is distributed in the hope that it will be useful, | |
| 13 but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
| 15 GNU General Public License for more details. | |
| 16 | |
| 17 You should have received a copy of the GNU General Public License | |
| 18 along with GCC; see the file COPYING3. If not see | |
| 19 <http://www.gnu.org/licenses/>. */ | |
| 20 | |
| 21 #include "config.h" | |
| 22 #include "system.h" | |
| 23 #include "coretypes.h" | |
| 24 #include "tm.h" | |
| 25 #include "tree.h" | |
|
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26 #include "rtl.h" /* FIXME: Only for ceil_log2, of all things... */ |
| 0 | 27 #include "ggc.h" |
| 28 #include "basic-block.h" | |
| 29 #include "tree-flow.h" | |
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30 #include "diagnostic-core.h" |
| 0 | 31 #include "gimple.h" |
| 32 | |
| 33 /* Rewriting a function into SSA form can create a huge number of PHIs | |
| 34 many of which may be thrown away shortly after their creation if jumps | |
| 35 were threaded through PHI nodes. | |
| 36 | |
| 37 While our garbage collection mechanisms will handle this situation, it | |
| 38 is extremely wasteful to create nodes and throw them away, especially | |
| 39 when the nodes can be reused. | |
| 40 | |
| 41 For PR 8361, we can significantly reduce the number of nodes allocated | |
| 42 and thus the total amount of memory allocated by managing PHIs a | |
| 43 little. This additionally helps reduce the amount of work done by the | |
| 44 garbage collector. Similar results have been seen on a wider variety | |
| 45 of tests (such as the compiler itself). | |
| 46 | |
| 47 Right now we maintain our free list on a per-function basis. It may | |
| 48 or may not make sense to maintain the free list for the duration of | |
| 49 a compilation unit. | |
| 50 | |
| 51 We could also use a zone allocator for these objects since they have | |
| 52 a very well defined lifetime. If someone wants to experiment with that | |
| 53 this is the place to try it. | |
| 54 | |
| 55 PHI nodes have different sizes, so we can't have a single list of all | |
| 56 the PHI nodes as it would be too expensive to walk down that list to | |
| 57 find a PHI of a suitable size. | |
| 58 | |
| 59 Instead we have an array of lists of free PHI nodes. The array is | |
| 60 indexed by the number of PHI alternatives that PHI node can hold. | |
| 61 Except for the last array member, which holds all remaining PHI | |
| 62 nodes. | |
| 63 | |
| 64 So to find a free PHI node, we compute its index into the free PHI | |
| 65 node array and see if there are any elements with an exact match. | |
| 66 If so, then we are done. Otherwise, we test the next larger size | |
| 67 up and continue until we are in the last array element. | |
| 68 | |
| 69 We do not actually walk members of the last array element. While it | |
| 70 might allow us to pick up a few reusable PHI nodes, it could potentially | |
| 71 be very expensive if the program has released a bunch of large PHI nodes, | |
| 72 but keeps asking for even larger PHI nodes. Experiments have shown that | |
| 73 walking the elements of the last array entry would result in finding less | |
| 74 than .1% additional reusable PHI nodes. | |
| 75 | |
| 76 Note that we can never have less than two PHI argument slots. Thus, | |
| 77 the -2 on all the calculations below. */ | |
| 78 | |
| 79 #define NUM_BUCKETS 10 | |
| 80 static GTY ((deletable (""))) VEC(gimple,gc) *free_phinodes[NUM_BUCKETS - 2]; | |
| 81 static unsigned long free_phinode_count; | |
| 82 | |
| 83 static int ideal_phi_node_len (int); | |
| 84 | |
| 85 #ifdef GATHER_STATISTICS | |
| 86 unsigned int phi_nodes_reused; | |
| 87 unsigned int phi_nodes_created; | |
| 88 #endif | |
| 89 | |
| 90 /* Initialize management of PHIs. */ | |
| 91 | |
| 92 void | |
| 93 init_phinodes (void) | |
| 94 { | |
| 95 int i; | |
| 96 | |
| 97 for (i = 0; i < NUM_BUCKETS - 2; i++) | |
| 98 free_phinodes[i] = NULL; | |
| 99 free_phinode_count = 0; | |
| 100 } | |
| 101 | |
| 102 /* Finalize management of PHIs. */ | |
| 103 | |
| 104 void | |
| 105 fini_phinodes (void) | |
| 106 { | |
| 107 int i; | |
| 108 | |
| 109 for (i = 0; i < NUM_BUCKETS - 2; i++) | |
| 110 free_phinodes[i] = NULL; | |
| 111 free_phinode_count = 0; | |
| 112 } | |
| 113 | |
| 114 /* Dump some simple statistics regarding the re-use of PHI nodes. */ | |
| 115 | |
| 116 #ifdef GATHER_STATISTICS | |
| 117 void | |
| 118 phinodes_print_statistics (void) | |
| 119 { | |
| 120 fprintf (stderr, "PHI nodes allocated: %u\n", phi_nodes_created); | |
| 121 fprintf (stderr, "PHI nodes reused: %u\n", phi_nodes_reused); | |
| 122 } | |
| 123 #endif | |
| 124 | |
| 125 /* Allocate a PHI node with at least LEN arguments. If the free list | |
| 126 happens to contain a PHI node with LEN arguments or more, return | |
| 127 that one. */ | |
| 128 | |
| 129 static inline gimple | |
| 130 allocate_phi_node (size_t len) | |
| 131 { | |
| 132 gimple phi; | |
| 133 size_t bucket = NUM_BUCKETS - 2; | |
| 134 size_t size = sizeof (struct gimple_statement_phi) | |
| 135 + (len - 1) * sizeof (struct phi_arg_d); | |
| 136 | |
| 137 if (free_phinode_count) | |
| 138 for (bucket = len - 2; bucket < NUM_BUCKETS - 2; bucket++) | |
| 139 if (free_phinodes[bucket]) | |
| 140 break; | |
| 141 | |
| 142 /* If our free list has an element, then use it. */ | |
| 143 if (bucket < NUM_BUCKETS - 2 | |
| 144 && gimple_phi_capacity (VEC_index (gimple, free_phinodes[bucket], 0)) | |
| 145 >= len) | |
| 146 { | |
| 147 free_phinode_count--; | |
| 148 phi = VEC_pop (gimple, free_phinodes[bucket]); | |
| 149 if (VEC_empty (gimple, free_phinodes[bucket])) | |
| 150 VEC_free (gimple, gc, free_phinodes[bucket]); | |
| 151 #ifdef GATHER_STATISTICS | |
| 152 phi_nodes_reused++; | |
| 153 #endif | |
| 154 } | |
| 155 else | |
| 156 { | |
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157 phi = ggc_alloc_gimple_statement_d (size); |
| 0 | 158 #ifdef GATHER_STATISTICS |
| 159 phi_nodes_created++; | |
| 160 { | |
| 161 enum gimple_alloc_kind kind = gimple_alloc_kind (GIMPLE_PHI); | |
| 162 gimple_alloc_counts[(int) kind]++; | |
| 163 gimple_alloc_sizes[(int) kind] += size; | |
| 164 } | |
| 165 #endif | |
| 166 } | |
| 167 | |
| 168 return phi; | |
| 169 } | |
| 170 | |
| 171 /* Given LEN, the original number of requested PHI arguments, return | |
| 172 a new, "ideal" length for the PHI node. The "ideal" length rounds | |
| 173 the total size of the PHI node up to the next power of two bytes. | |
| 174 | |
| 175 Rounding up will not result in wasting any memory since the size request | |
| 176 will be rounded up by the GC system anyway. [ Note this is not entirely | |
| 177 true since the original length might have fit on one of the special | |
| 178 GC pages. ] By rounding up, we may avoid the need to reallocate the | |
| 179 PHI node later if we increase the number of arguments for the PHI. */ | |
| 180 | |
| 181 static int | |
| 182 ideal_phi_node_len (int len) | |
| 183 { | |
| 184 size_t size, new_size; | |
| 185 int log2, new_len; | |
| 186 | |
| 187 /* We do not support allocations of less than two PHI argument slots. */ | |
| 188 if (len < 2) | |
| 189 len = 2; | |
| 190 | |
| 191 /* Compute the number of bytes of the original request. */ | |
| 192 size = sizeof (struct gimple_statement_phi) | |
| 193 + (len - 1) * sizeof (struct phi_arg_d); | |
| 194 | |
| 195 /* Round it up to the next power of two. */ | |
| 196 log2 = ceil_log2 (size); | |
| 197 new_size = 1 << log2; | |
| 198 | |
| 199 /* Now compute and return the number of PHI argument slots given an | |
| 200 ideal size allocation. */ | |
| 201 new_len = len + (new_size - size) / sizeof (struct phi_arg_d); | |
| 202 return new_len; | |
| 203 } | |
| 204 | |
| 205 /* Return a PHI node with LEN argument slots for variable VAR. */ | |
| 206 | |
| 207 gimple | |
| 208 make_phi_node (tree var, int len) | |
| 209 { | |
| 210 gimple phi; | |
| 211 int capacity, i; | |
| 212 | |
| 213 capacity = ideal_phi_node_len (len); | |
| 214 | |
| 215 phi = allocate_phi_node (capacity); | |
| 216 | |
| 217 /* We need to clear the entire PHI node, including the argument | |
| 218 portion, because we represent a "missing PHI argument" by placing | |
| 219 NULL_TREE in PHI_ARG_DEF. */ | |
| 220 memset (phi, 0, (sizeof (struct gimple_statement_phi) | |
| 221 - sizeof (struct phi_arg_d) | |
| 222 + sizeof (struct phi_arg_d) * len)); | |
| 223 phi->gsbase.code = GIMPLE_PHI; | |
| 224 phi->gimple_phi.nargs = len; | |
| 225 phi->gimple_phi.capacity = capacity; | |
| 226 if (TREE_CODE (var) == SSA_NAME) | |
| 227 gimple_phi_set_result (phi, var); | |
| 228 else | |
| 229 gimple_phi_set_result (phi, make_ssa_name (var, phi)); | |
| 230 | |
| 231 for (i = 0; i < capacity; i++) | |
| 232 { | |
| 233 use_operand_p imm; | |
|
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235 gimple_phi_arg_set_location (phi, i, UNKNOWN_LOCATION); |
| 0 | 236 imm = gimple_phi_arg_imm_use_ptr (phi, i); |
| 237 imm->use = gimple_phi_arg_def_ptr (phi, i); | |
| 238 imm->prev = NULL; | |
| 239 imm->next = NULL; | |
| 240 imm->loc.stmt = phi; | |
| 241 } | |
| 242 | |
| 243 return phi; | |
| 244 } | |
| 245 | |
| 246 /* We no longer need PHI, release it so that it may be reused. */ | |
| 247 | |
| 248 void | |
| 249 release_phi_node (gimple phi) | |
| 250 { | |
| 251 size_t bucket; | |
| 252 size_t len = gimple_phi_capacity (phi); | |
| 253 size_t x; | |
| 254 | |
| 255 for (x = 0; x < gimple_phi_num_args (phi); x++) | |
| 256 { | |
| 257 use_operand_p imm; | |
| 258 imm = gimple_phi_arg_imm_use_ptr (phi, x); | |
| 259 delink_imm_use (imm); | |
| 260 } | |
| 261 | |
| 262 bucket = len > NUM_BUCKETS - 1 ? NUM_BUCKETS - 1 : len; | |
| 263 bucket -= 2; | |
| 264 VEC_safe_push (gimple, gc, free_phinodes[bucket], phi); | |
| 265 free_phinode_count++; | |
| 266 } | |
| 267 | |
| 268 | |
| 269 /* Resize an existing PHI node. The only way is up. Return the | |
| 270 possibly relocated phi. */ | |
| 271 | |
| 272 static void | |
| 273 resize_phi_node (gimple *phi, size_t len) | |
| 274 { | |
| 275 size_t old_size, i; | |
| 276 gimple new_phi; | |
| 277 | |
| 278 gcc_assert (len > gimple_phi_capacity (*phi)); | |
| 279 | |
| 280 /* The garbage collector will not look at the PHI node beyond the | |
| 281 first PHI_NUM_ARGS elements. Therefore, all we have to copy is a | |
| 282 portion of the PHI node currently in use. */ | |
| 283 old_size = sizeof (struct gimple_statement_phi) | |
| 284 + (gimple_phi_num_args (*phi) - 1) * sizeof (struct phi_arg_d); | |
| 285 | |
| 286 new_phi = allocate_phi_node (len); | |
| 287 | |
| 288 memcpy (new_phi, *phi, old_size); | |
| 289 | |
| 290 for (i = 0; i < gimple_phi_num_args (new_phi); i++) | |
| 291 { | |
| 292 use_operand_p imm, old_imm; | |
| 293 imm = gimple_phi_arg_imm_use_ptr (new_phi, i); | |
| 294 old_imm = gimple_phi_arg_imm_use_ptr (*phi, i); | |
| 295 imm->use = gimple_phi_arg_def_ptr (new_phi, i); | |
| 296 relink_imm_use_stmt (imm, old_imm, new_phi); | |
| 297 } | |
| 298 | |
| 299 new_phi->gimple_phi.capacity = len; | |
| 300 | |
| 301 for (i = gimple_phi_num_args (new_phi); i < len; i++) | |
| 302 { | |
| 303 use_operand_p imm; | |
|
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305 gimple_phi_arg_set_location (new_phi, i, UNKNOWN_LOCATION); |
| 0 | 306 imm = gimple_phi_arg_imm_use_ptr (new_phi, i); |
| 307 imm->use = gimple_phi_arg_def_ptr (new_phi, i); | |
| 308 imm->prev = NULL; | |
| 309 imm->next = NULL; | |
| 310 imm->loc.stmt = new_phi; | |
| 311 } | |
| 312 | |
| 313 *phi = new_phi; | |
| 314 } | |
| 315 | |
| 316 /* Reserve PHI arguments for a new edge to basic block BB. */ | |
| 317 | |
| 318 void | |
| 319 reserve_phi_args_for_new_edge (basic_block bb) | |
| 320 { | |
| 321 size_t len = EDGE_COUNT (bb->preds); | |
| 322 size_t cap = ideal_phi_node_len (len + 4); | |
| 323 gimple_stmt_iterator gsi; | |
| 324 | |
| 325 for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi)) | |
| 326 { | |
| 327 gimple *loc = gsi_stmt_ptr (&gsi); | |
| 328 | |
| 329 if (len > gimple_phi_capacity (*loc)) | |
| 330 { | |
| 331 gimple old_phi = *loc; | |
| 332 | |
| 333 resize_phi_node (loc, cap); | |
| 334 | |
| 335 /* The result of the PHI is defined by this PHI node. */ | |
| 336 SSA_NAME_DEF_STMT (gimple_phi_result (*loc)) = *loc; | |
| 337 | |
| 338 release_phi_node (old_phi); | |
| 339 } | |
| 340 | |
| 341 /* We represent a "missing PHI argument" by placing NULL_TREE in | |
| 342 the corresponding slot. If PHI arguments were added | |
| 343 immediately after an edge is created, this zeroing would not | |
| 344 be necessary, but unfortunately this is not the case. For | |
| 345 example, the loop optimizer duplicates several basic blocks, | |
| 346 redirects edges, and then fixes up PHI arguments later in | |
| 347 batch. */ | |
| 348 SET_PHI_ARG_DEF (*loc, len - 1, NULL_TREE); | |
| 349 | |
| 350 (*loc)->gimple_phi.nargs++; | |
| 351 } | |
| 352 } | |
| 353 | |
| 354 /* Adds PHI to BB. */ | |
| 355 | |
|
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356 void |
| 0 | 357 add_phi_node_to_bb (gimple phi, basic_block bb) |
| 358 { | |
| 359 gimple_stmt_iterator gsi; | |
| 360 /* Add the new PHI node to the list of PHI nodes for block BB. */ | |
| 361 if (phi_nodes (bb) == NULL) | |
| 362 set_phi_nodes (bb, gimple_seq_alloc ()); | |
| 363 | |
| 364 gsi = gsi_last (phi_nodes (bb)); | |
| 365 gsi_insert_after (&gsi, phi, GSI_NEW_STMT); | |
| 366 | |
| 367 /* Associate BB to the PHI node. */ | |
| 368 gimple_set_bb (phi, bb); | |
| 369 | |
| 370 } | |
| 371 | |
| 372 /* Create a new PHI node for variable VAR at basic block BB. */ | |
| 373 | |
| 374 gimple | |
| 375 create_phi_node (tree var, basic_block bb) | |
| 376 { | |
| 377 gimple phi = make_phi_node (var, EDGE_COUNT (bb->preds)); | |
| 378 | |
| 379 add_phi_node_to_bb (phi, bb); | |
| 380 return phi; | |
| 381 } | |
| 382 | |
| 383 | |
| 384 /* Add a new argument to PHI node PHI. DEF is the incoming reaching | |
| 385 definition and E is the edge through which DEF reaches PHI. The new | |
| 386 argument is added at the end of the argument list. | |
| 387 If PHI has reached its maximum capacity, add a few slots. In this case, | |
| 388 PHI points to the reallocated phi node when we return. */ | |
| 389 | |
| 390 void | |
|
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391 add_phi_arg (gimple phi, tree def, edge e, source_location locus) |
| 0 | 392 { |
| 393 basic_block bb = e->dest; | |
| 394 | |
| 395 gcc_assert (bb == gimple_bb (phi)); | |
| 396 | |
| 397 /* We resize PHI nodes upon edge creation. We should always have | |
| 398 enough room at this point. */ | |
| 399 gcc_assert (gimple_phi_num_args (phi) <= gimple_phi_capacity (phi)); | |
| 400 | |
| 401 /* We resize PHI nodes upon edge creation. We should always have | |
| 402 enough room at this point. */ | |
| 403 gcc_assert (e->dest_idx < gimple_phi_num_args (phi)); | |
| 404 | |
| 405 /* Copy propagation needs to know what object occur in abnormal | |
| 406 PHI nodes. This is a convenient place to record such information. */ | |
| 407 if (e->flags & EDGE_ABNORMAL) | |
| 408 { | |
| 409 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (def) = 1; | |
| 410 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (PHI_RESULT (phi)) = 1; | |
| 411 } | |
| 412 | |
| 413 SET_PHI_ARG_DEF (phi, e->dest_idx, def); | |
|
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414 gimple_phi_arg_set_location (phi, e->dest_idx, locus); |
| 0 | 415 } |
| 416 | |
| 417 | |
| 418 /* Remove the Ith argument from PHI's argument list. This routine | |
| 419 implements removal by swapping the last alternative with the | |
| 420 alternative we want to delete and then shrinking the vector, which | |
| 421 is consistent with how we remove an edge from the edge vector. */ | |
| 422 | |
| 423 static void | |
| 424 remove_phi_arg_num (gimple phi, int i) | |
| 425 { | |
| 426 int num_elem = gimple_phi_num_args (phi); | |
| 427 | |
| 428 gcc_assert (i < num_elem); | |
| 429 | |
| 430 /* Delink the item which is being removed. */ | |
| 431 delink_imm_use (gimple_phi_arg_imm_use_ptr (phi, i)); | |
| 432 | |
| 433 /* If it is not the last element, move the last element | |
| 434 to the element we want to delete, resetting all the links. */ | |
| 435 if (i != num_elem - 1) | |
| 436 { | |
| 437 use_operand_p old_p, new_p; | |
| 438 old_p = gimple_phi_arg_imm_use_ptr (phi, num_elem - 1); | |
| 439 new_p = gimple_phi_arg_imm_use_ptr (phi, i); | |
| 440 /* Set use on new node, and link into last element's place. */ | |
| 441 *(new_p->use) = *(old_p->use); | |
| 442 relink_imm_use (new_p, old_p); | |
|
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443 /* Move the location as well. */ |
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444 gimple_phi_arg_set_location (phi, i, |
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445 gimple_phi_arg_location (phi, num_elem - 1)); |
| 0 | 446 } |
| 447 | |
| 448 /* Shrink the vector and return. Note that we do not have to clear | |
| 449 PHI_ARG_DEF because the garbage collector will not look at those | |
| 450 elements beyond the first PHI_NUM_ARGS elements of the array. */ | |
| 451 phi->gimple_phi.nargs--; | |
| 452 } | |
| 453 | |
| 454 | |
| 455 /* Remove all PHI arguments associated with edge E. */ | |
| 456 | |
| 457 void | |
| 458 remove_phi_args (edge e) | |
| 459 { | |
| 460 gimple_stmt_iterator gsi; | |
| 461 | |
| 462 for (gsi = gsi_start_phis (e->dest); !gsi_end_p (gsi); gsi_next (&gsi)) | |
| 463 remove_phi_arg_num (gsi_stmt (gsi), e->dest_idx); | |
| 464 } | |
| 465 | |
| 466 | |
| 467 /* Remove the PHI node pointed-to by iterator GSI from basic block BB. After | |
| 468 removal, iterator GSI is updated to point to the next PHI node in the | |
| 469 sequence. If RELEASE_LHS_P is true, the LHS of this PHI node is released | |
| 470 into the free pool of SSA names. */ | |
| 471 | |
| 472 void | |
| 473 remove_phi_node (gimple_stmt_iterator *gsi, bool release_lhs_p) | |
| 474 { | |
| 475 gimple phi = gsi_stmt (*gsi); | |
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update gcc from gcc-4.5.0 to gcc-4.6
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parents:
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476 |
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update gcc from gcc-4.5.0 to gcc-4.6
ryoma <e075725@ie.u-ryukyu.ac.jp>
parents:
55
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changeset
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477 if (release_lhs_p) |
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update gcc from gcc-4.5.0 to gcc-4.6
ryoma <e075725@ie.u-ryukyu.ac.jp>
parents:
55
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changeset
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478 insert_debug_temps_for_defs (gsi); |
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update gcc from gcc-4.5.0 to gcc-4.6
ryoma <e075725@ie.u-ryukyu.ac.jp>
parents:
55
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changeset
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479 |
| 0 | 480 gsi_remove (gsi, false); |
| 481 | |
| 482 /* If we are deleting the PHI node, then we should release the | |
| 483 SSA_NAME node so that it can be reused. */ | |
| 484 release_phi_node (phi); | |
| 485 if (release_lhs_p) | |
| 486 release_ssa_name (gimple_phi_result (phi)); | |
| 487 } | |
| 488 | |
| 489 /* Remove all the phi nodes from BB. */ | |
| 490 | |
| 491 void | |
| 492 remove_phi_nodes (basic_block bb) | |
| 493 { | |
| 494 gimple_stmt_iterator gsi; | |
| 495 | |
| 496 for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); ) | |
| 497 remove_phi_node (&gsi, true); | |
| 498 | |
| 499 set_phi_nodes (bb, NULL); | |
| 500 } | |
| 501 | |
| 502 #include "gt-tree-phinodes.h" |