Mercurial > hg > CbC > CbC_gcc
annotate gcc/tree-phinodes.c @ 158:494b0b89df80 default tip
...
| 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 /* Generic routines for manipulating PHIs |
| 145 | 2 Copyright (C) 2003-2020 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" |
| 25 #include "gimple.h" | |
| 111 | 26 #include "ssa.h" |
| 27 #include "fold-const.h" | |
| 28 #include "gimple-iterator.h" | |
| 29 #include "tree-ssa.h" | |
| 0 | 30 |
| 31 /* Rewriting a function into SSA form can create a huge number of PHIs | |
| 32 many of which may be thrown away shortly after their creation if jumps | |
| 33 were threaded through PHI nodes. | |
| 34 | |
| 35 While our garbage collection mechanisms will handle this situation, it | |
| 36 is extremely wasteful to create nodes and throw them away, especially | |
| 37 when the nodes can be reused. | |
| 38 | |
| 39 For PR 8361, we can significantly reduce the number of nodes allocated | |
| 40 and thus the total amount of memory allocated by managing PHIs a | |
| 41 little. This additionally helps reduce the amount of work done by the | |
| 42 garbage collector. Similar results have been seen on a wider variety | |
| 43 of tests (such as the compiler itself). | |
| 44 | |
| 45 PHI nodes have different sizes, so we can't have a single list of all | |
| 46 the PHI nodes as it would be too expensive to walk down that list to | |
| 47 find a PHI of a suitable size. | |
| 48 | |
| 49 Instead we have an array of lists of free PHI nodes. The array is | |
| 50 indexed by the number of PHI alternatives that PHI node can hold. | |
| 51 Except for the last array member, which holds all remaining PHI | |
| 52 nodes. | |
| 53 | |
| 54 So to find a free PHI node, we compute its index into the free PHI | |
| 55 node array and see if there are any elements with an exact match. | |
| 56 If so, then we are done. Otherwise, we test the next larger size | |
| 57 up and continue until we are in the last array element. | |
| 58 | |
| 59 We do not actually walk members of the last array element. While it | |
| 60 might allow us to pick up a few reusable PHI nodes, it could potentially | |
| 61 be very expensive if the program has released a bunch of large PHI nodes, | |
| 62 but keeps asking for even larger PHI nodes. Experiments have shown that | |
| 63 walking the elements of the last array entry would result in finding less | |
| 64 than .1% additional reusable PHI nodes. | |
| 65 | |
| 66 Note that we can never have less than two PHI argument slots. Thus, | |
| 67 the -2 on all the calculations below. */ | |
| 68 | |
| 69 #define NUM_BUCKETS 10 | |
| 111 | 70 static GTY ((deletable (""))) vec<gimple *, va_gc> *free_phinodes[NUM_BUCKETS - 2]; |
| 0 | 71 static unsigned long free_phinode_count; |
| 72 | |
| 73 static int ideal_phi_node_len (int); | |
| 74 | |
| 75 unsigned int phi_nodes_reused; | |
| 76 unsigned int phi_nodes_created; | |
| 77 | |
| 78 /* Dump some simple statistics regarding the re-use of PHI nodes. */ | |
| 79 | |
| 80 void | |
| 81 phinodes_print_statistics (void) | |
| 82 { | |
| 145 | 83 fprintf (stderr, "%-32s" PRsa (11) "\n", "PHI nodes allocated:", |
| 84 SIZE_AMOUNT (phi_nodes_created)); | |
| 85 fprintf (stderr, "%-32s" PRsa (11) "\n", "PHI nodes reused:", | |
| 86 SIZE_AMOUNT (phi_nodes_reused)); | |
| 0 | 87 } |
| 88 | |
| 89 /* Allocate a PHI node with at least LEN arguments. If the free list | |
| 90 happens to contain a PHI node with LEN arguments or more, return | |
| 91 that one. */ | |
| 92 | |
| 111 | 93 static inline gphi * |
| 0 | 94 allocate_phi_node (size_t len) |
| 95 { | |
| 111 | 96 gphi *phi; |
| 0 | 97 size_t bucket = NUM_BUCKETS - 2; |
| 111 | 98 size_t size = sizeof (struct gphi) |
| 0 | 99 + (len - 1) * sizeof (struct phi_arg_d); |
| 100 | |
| 101 if (free_phinode_count) | |
| 102 for (bucket = len - 2; bucket < NUM_BUCKETS - 2; bucket++) | |
| 103 if (free_phinodes[bucket]) | |
| 104 break; | |
| 105 | |
| 106 /* If our free list has an element, then use it. */ | |
| 107 if (bucket < NUM_BUCKETS - 2 | |
| 111 | 108 && gimple_phi_capacity ((*free_phinodes[bucket])[0]) >= len) |
| 0 | 109 { |
| 110 free_phinode_count--; | |
| 111 | 111 phi = as_a <gphi *> (free_phinodes[bucket]->pop ()); |
| 112 if (free_phinodes[bucket]->is_empty ()) | |
| 113 vec_free (free_phinodes[bucket]); | |
| 114 if (GATHER_STATISTICS) | |
| 115 phi_nodes_reused++; | |
| 0 | 116 } |
| 117 else | |
| 118 { | |
| 111 | 119 phi = static_cast <gphi *> (ggc_internal_alloc (size)); |
| 120 if (GATHER_STATISTICS) | |
| 0 | 121 { |
| 122 enum gimple_alloc_kind kind = gimple_alloc_kind (GIMPLE_PHI); | |
| 111 | 123 phi_nodes_created++; |
| 124 gimple_alloc_counts[(int) kind]++; | |
| 125 gimple_alloc_sizes[(int) kind] += size; | |
| 0 | 126 } |
| 127 } | |
| 128 | |
| 129 return phi; | |
| 130 } | |
| 131 | |
| 132 /* Given LEN, the original number of requested PHI arguments, return | |
| 133 a new, "ideal" length for the PHI node. The "ideal" length rounds | |
| 134 the total size of the PHI node up to the next power of two bytes. | |
| 135 | |
| 136 Rounding up will not result in wasting any memory since the size request | |
| 137 will be rounded up by the GC system anyway. [ Note this is not entirely | |
| 138 true since the original length might have fit on one of the special | |
| 139 GC pages. ] By rounding up, we may avoid the need to reallocate the | |
| 140 PHI node later if we increase the number of arguments for the PHI. */ | |
| 141 | |
| 142 static int | |
| 143 ideal_phi_node_len (int len) | |
| 144 { | |
| 145 size_t size, new_size; | |
| 146 int log2, new_len; | |
| 147 | |
| 148 /* We do not support allocations of less than two PHI argument slots. */ | |
| 149 if (len < 2) | |
| 150 len = 2; | |
| 151 | |
| 152 /* Compute the number of bytes of the original request. */ | |
| 111 | 153 size = sizeof (struct gphi) |
| 0 | 154 + (len - 1) * sizeof (struct phi_arg_d); |
| 155 | |
| 156 /* Round it up to the next power of two. */ | |
| 157 log2 = ceil_log2 (size); | |
| 158 new_size = 1 << log2; | |
| 159 | |
| 160 /* Now compute and return the number of PHI argument slots given an | |
| 161 ideal size allocation. */ | |
| 162 new_len = len + (new_size - size) / sizeof (struct phi_arg_d); | |
| 163 return new_len; | |
| 164 } | |
| 165 | |
| 166 /* Return a PHI node with LEN argument slots for variable VAR. */ | |
| 167 | |
| 111 | 168 static gphi * |
| 0 | 169 make_phi_node (tree var, int len) |
| 170 { | |
| 111 | 171 gphi *phi; |
| 0 | 172 int capacity, i; |
| 173 | |
| 174 capacity = ideal_phi_node_len (len); | |
| 175 | |
| 176 phi = allocate_phi_node (capacity); | |
| 177 | |
| 178 /* We need to clear the entire PHI node, including the argument | |
| 179 portion, because we represent a "missing PHI argument" by placing | |
| 180 NULL_TREE in PHI_ARG_DEF. */ | |
| 111 | 181 memset (phi, 0, (sizeof (struct gphi) |
| 0 | 182 - sizeof (struct phi_arg_d) |
| 183 + sizeof (struct phi_arg_d) * len)); | |
| 111 | 184 phi->code = GIMPLE_PHI; |
| 185 gimple_init_singleton (phi); | |
| 186 phi->nargs = len; | |
| 187 phi->capacity = capacity; | |
| 188 if (!var) | |
| 189 ; | |
| 190 else if (TREE_CODE (var) == SSA_NAME) | |
| 0 | 191 gimple_phi_set_result (phi, var); |
| 192 else | |
| 193 gimple_phi_set_result (phi, make_ssa_name (var, phi)); | |
| 194 | |
| 111 | 195 for (i = 0; i < len; i++) |
| 0 | 196 { |
| 197 use_operand_p imm; | |
|
55
77e2b8dfacca
update it from 4.4.3 to 4.5.0
ryoma <e075725@ie.u-ryukyu.ac.jp>
parents:
0
diff
changeset
|
198 |
|
77e2b8dfacca
update it from 4.4.3 to 4.5.0
ryoma <e075725@ie.u-ryukyu.ac.jp>
parents:
0
diff
changeset
|
199 gimple_phi_arg_set_location (phi, i, UNKNOWN_LOCATION); |
| 0 | 200 imm = gimple_phi_arg_imm_use_ptr (phi, i); |
| 201 imm->use = gimple_phi_arg_def_ptr (phi, i); | |
| 202 imm->prev = NULL; | |
| 203 imm->next = NULL; | |
| 204 imm->loc.stmt = phi; | |
| 205 } | |
| 206 | |
| 207 return phi; | |
| 208 } | |
| 209 | |
| 210 /* We no longer need PHI, release it so that it may be reused. */ | |
| 211 | |
| 111 | 212 static void |
| 213 release_phi_node (gimple *phi) | |
| 0 | 214 { |
| 215 size_t bucket; | |
| 216 size_t len = gimple_phi_capacity (phi); | |
| 217 size_t x; | |
| 218 | |
| 219 for (x = 0; x < gimple_phi_num_args (phi); x++) | |
| 220 { | |
| 221 use_operand_p imm; | |
| 222 imm = gimple_phi_arg_imm_use_ptr (phi, x); | |
| 223 delink_imm_use (imm); | |
| 224 } | |
| 225 | |
| 226 bucket = len > NUM_BUCKETS - 1 ? NUM_BUCKETS - 1 : len; | |
| 227 bucket -= 2; | |
| 111 | 228 vec_safe_push (free_phinodes[bucket], phi); |
| 0 | 229 free_phinode_count++; |
| 230 } | |
| 231 | |
| 232 | |
| 233 /* Resize an existing PHI node. The only way is up. Return the | |
| 234 possibly relocated phi. */ | |
| 235 | |
| 111 | 236 static gphi * |
| 237 resize_phi_node (gphi *phi, size_t len) | |
| 0 | 238 { |
| 239 size_t old_size, i; | |
| 111 | 240 gphi *new_phi; |
| 0 | 241 |
| 111 | 242 gcc_assert (len > gimple_phi_capacity (phi)); |
| 0 | 243 |
| 244 /* The garbage collector will not look at the PHI node beyond the | |
| 245 first PHI_NUM_ARGS elements. Therefore, all we have to copy is a | |
| 246 portion of the PHI node currently in use. */ | |
| 111 | 247 old_size = sizeof (struct gphi) |
| 248 + (gimple_phi_num_args (phi) - 1) * sizeof (struct phi_arg_d); | |
| 0 | 249 |
| 250 new_phi = allocate_phi_node (len); | |
| 251 | |
| 111 | 252 memcpy (new_phi, phi, old_size); |
| 253 memset ((char *)new_phi + old_size, 0, | |
| 254 (sizeof (struct gphi) | |
| 255 - sizeof (struct phi_arg_d) | |
| 256 + sizeof (struct phi_arg_d) * len) - old_size); | |
| 0 | 257 |
| 258 for (i = 0; i < gimple_phi_num_args (new_phi); i++) | |
| 259 { | |
| 260 use_operand_p imm, old_imm; | |
| 261 imm = gimple_phi_arg_imm_use_ptr (new_phi, i); | |
| 111 | 262 old_imm = gimple_phi_arg_imm_use_ptr (phi, i); |
| 0 | 263 imm->use = gimple_phi_arg_def_ptr (new_phi, i); |
| 264 relink_imm_use_stmt (imm, old_imm, new_phi); | |
| 265 } | |
| 266 | |
| 111 | 267 new_phi->capacity = len; |
|
55
77e2b8dfacca
update it from 4.4.3 to 4.5.0
ryoma <e075725@ie.u-ryukyu.ac.jp>
parents:
0
diff
changeset
|
268 |
| 111 | 269 return new_phi; |
| 0 | 270 } |
| 271 | |
| 272 /* Reserve PHI arguments for a new edge to basic block BB. */ | |
| 273 | |
| 274 void | |
| 275 reserve_phi_args_for_new_edge (basic_block bb) | |
| 276 { | |
| 277 size_t len = EDGE_COUNT (bb->preds); | |
| 278 size_t cap = ideal_phi_node_len (len + 4); | |
| 111 | 279 gphi_iterator gsi; |
| 0 | 280 |
| 281 for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi)) | |
| 282 { | |
| 111 | 283 gphi *stmt = gsi.phi (); |
| 0 | 284 |
| 111 | 285 if (len > gimple_phi_capacity (stmt)) |
| 0 | 286 { |
| 111 | 287 gphi *new_phi = resize_phi_node (stmt, cap); |
| 0 | 288 |
| 289 /* The result of the PHI is defined by this PHI node. */ | |
| 111 | 290 SSA_NAME_DEF_STMT (gimple_phi_result (new_phi)) = new_phi; |
| 291 gsi_set_stmt (&gsi, new_phi); | |
| 0 | 292 |
| 111 | 293 release_phi_node (stmt); |
| 294 stmt = new_phi; | |
| 0 | 295 } |
| 296 | |
| 111 | 297 stmt->nargs++; |
| 298 | |
| 0 | 299 /* We represent a "missing PHI argument" by placing NULL_TREE in |
| 300 the corresponding slot. If PHI arguments were added | |
| 301 immediately after an edge is created, this zeroing would not | |
| 302 be necessary, but unfortunately this is not the case. For | |
| 303 example, the loop optimizer duplicates several basic blocks, | |
| 304 redirects edges, and then fixes up PHI arguments later in | |
| 305 batch. */ | |
| 111 | 306 use_operand_p imm = gimple_phi_arg_imm_use_ptr (stmt, len - 1); |
| 307 imm->use = gimple_phi_arg_def_ptr (stmt, len - 1); | |
| 308 imm->prev = NULL; | |
| 309 imm->next = NULL; | |
| 310 imm->loc.stmt = stmt; | |
| 311 SET_PHI_ARG_DEF (stmt, len - 1, NULL_TREE); | |
| 312 gimple_phi_arg_set_location (stmt, len - 1, UNKNOWN_LOCATION); | |
| 0 | 313 } |
| 314 } | |
| 315 | |
| 316 /* Adds PHI to BB. */ | |
| 317 | |
|
55
77e2b8dfacca
update it from 4.4.3 to 4.5.0
ryoma <e075725@ie.u-ryukyu.ac.jp>
parents:
0
diff
changeset
|
318 void |
| 111 | 319 add_phi_node_to_bb (gphi *phi, basic_block bb) |
| 0 | 320 { |
| 111 | 321 gimple_seq seq = phi_nodes (bb); |
| 0 | 322 /* Add the new PHI node to the list of PHI nodes for block BB. */ |
| 111 | 323 if (seq == NULL) |
| 324 set_phi_nodes (bb, gimple_seq_alloc_with_stmt (phi)); | |
| 325 else | |
| 326 { | |
| 327 gimple_seq_add_stmt (&seq, phi); | |
| 328 gcc_assert (seq == phi_nodes (bb)); | |
| 329 } | |
| 0 | 330 |
| 331 /* Associate BB to the PHI node. */ | |
| 332 gimple_set_bb (phi, bb); | |
| 333 | |
| 334 } | |
| 335 | |
| 336 /* Create a new PHI node for variable VAR at basic block BB. */ | |
| 337 | |
| 111 | 338 gphi * |
| 0 | 339 create_phi_node (tree var, basic_block bb) |
| 340 { | |
| 111 | 341 gphi *phi = make_phi_node (var, EDGE_COUNT (bb->preds)); |
| 0 | 342 |
| 343 add_phi_node_to_bb (phi, bb); | |
| 344 return phi; | |
| 345 } | |
| 346 | |
| 347 | |
| 348 /* Add a new argument to PHI node PHI. DEF is the incoming reaching | |
| 349 definition and E is the edge through which DEF reaches PHI. The new | |
| 350 argument is added at the end of the argument list. | |
| 351 If PHI has reached its maximum capacity, add a few slots. In this case, | |
| 352 PHI points to the reallocated phi node when we return. */ | |
| 353 | |
| 354 void | |
| 145 | 355 add_phi_arg (gphi *phi, tree def, edge e, location_t locus) |
| 0 | 356 { |
| 357 basic_block bb = e->dest; | |
| 358 | |
| 359 gcc_assert (bb == gimple_bb (phi)); | |
| 360 | |
| 361 /* We resize PHI nodes upon edge creation. We should always have | |
| 362 enough room at this point. */ | |
| 363 gcc_assert (gimple_phi_num_args (phi) <= gimple_phi_capacity (phi)); | |
| 364 | |
| 365 /* We resize PHI nodes upon edge creation. We should always have | |
| 366 enough room at this point. */ | |
| 367 gcc_assert (e->dest_idx < gimple_phi_num_args (phi)); | |
| 368 | |
| 369 /* Copy propagation needs to know what object occur in abnormal | |
| 370 PHI nodes. This is a convenient place to record such information. */ | |
| 371 if (e->flags & EDGE_ABNORMAL) | |
| 372 { | |
| 373 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (def) = 1; | |
| 374 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (PHI_RESULT (phi)) = 1; | |
| 375 } | |
| 376 | |
| 377 SET_PHI_ARG_DEF (phi, e->dest_idx, def); | |
|
55
77e2b8dfacca
update it from 4.4.3 to 4.5.0
ryoma <e075725@ie.u-ryukyu.ac.jp>
parents:
0
diff
changeset
|
378 gimple_phi_arg_set_location (phi, e->dest_idx, locus); |
| 0 | 379 } |
| 380 | |
| 381 | |
| 382 /* Remove the Ith argument from PHI's argument list. This routine | |
| 383 implements removal by swapping the last alternative with the | |
| 384 alternative we want to delete and then shrinking the vector, which | |
| 385 is consistent with how we remove an edge from the edge vector. */ | |
| 386 | |
| 387 static void | |
| 111 | 388 remove_phi_arg_num (gphi *phi, int i) |
| 0 | 389 { |
| 390 int num_elem = gimple_phi_num_args (phi); | |
| 391 | |
| 392 gcc_assert (i < num_elem); | |
| 393 | |
| 394 /* Delink the item which is being removed. */ | |
| 395 delink_imm_use (gimple_phi_arg_imm_use_ptr (phi, i)); | |
| 396 | |
| 397 /* If it is not the last element, move the last element | |
| 398 to the element we want to delete, resetting all the links. */ | |
| 399 if (i != num_elem - 1) | |
| 400 { | |
| 401 use_operand_p old_p, new_p; | |
| 402 old_p = gimple_phi_arg_imm_use_ptr (phi, num_elem - 1); | |
| 403 new_p = gimple_phi_arg_imm_use_ptr (phi, i); | |
| 404 /* Set use on new node, and link into last element's place. */ | |
| 405 *(new_p->use) = *(old_p->use); | |
| 406 relink_imm_use (new_p, old_p); | |
|
55
77e2b8dfacca
update it from 4.4.3 to 4.5.0
ryoma <e075725@ie.u-ryukyu.ac.jp>
parents:
0
diff
changeset
|
407 /* Move the location as well. */ |
|
77e2b8dfacca
update it from 4.4.3 to 4.5.0
ryoma <e075725@ie.u-ryukyu.ac.jp>
parents:
0
diff
changeset
|
408 gimple_phi_arg_set_location (phi, i, |
|
77e2b8dfacca
update it from 4.4.3 to 4.5.0
ryoma <e075725@ie.u-ryukyu.ac.jp>
parents:
0
diff
changeset
|
409 gimple_phi_arg_location (phi, num_elem - 1)); |
| 0 | 410 } |
| 411 | |
| 412 /* Shrink the vector and return. Note that we do not have to clear | |
| 413 PHI_ARG_DEF because the garbage collector will not look at those | |
| 414 elements beyond the first PHI_NUM_ARGS elements of the array. */ | |
| 111 | 415 phi->nargs--; |
| 0 | 416 } |
| 417 | |
| 418 | |
| 419 /* Remove all PHI arguments associated with edge E. */ | |
| 420 | |
| 421 void | |
| 422 remove_phi_args (edge e) | |
| 423 { | |
| 111 | 424 gphi_iterator gsi; |
| 0 | 425 |
| 426 for (gsi = gsi_start_phis (e->dest); !gsi_end_p (gsi); gsi_next (&gsi)) | |
| 111 | 427 remove_phi_arg_num (gsi.phi (), |
| 428 e->dest_idx); | |
| 0 | 429 } |
| 430 | |
| 431 | |
| 432 /* Remove the PHI node pointed-to by iterator GSI from basic block BB. After | |
| 433 removal, iterator GSI is updated to point to the next PHI node in the | |
| 434 sequence. If RELEASE_LHS_P is true, the LHS of this PHI node is released | |
| 435 into the free pool of SSA names. */ | |
| 436 | |
| 437 void | |
| 438 remove_phi_node (gimple_stmt_iterator *gsi, bool release_lhs_p) | |
| 439 { | |
| 111 | 440 gimple *phi = gsi_stmt (*gsi); |
|
63
b7f97abdc517
update gcc from gcc-4.5.0 to gcc-4.6
ryoma <e075725@ie.u-ryukyu.ac.jp>
parents:
55
diff
changeset
|
441 |
|
b7f97abdc517
update gcc from gcc-4.5.0 to gcc-4.6
ryoma <e075725@ie.u-ryukyu.ac.jp>
parents:
55
diff
changeset
|
442 if (release_lhs_p) |
|
b7f97abdc517
update gcc from gcc-4.5.0 to gcc-4.6
ryoma <e075725@ie.u-ryukyu.ac.jp>
parents:
55
diff
changeset
|
443 insert_debug_temps_for_defs (gsi); |
|
b7f97abdc517
update gcc from gcc-4.5.0 to gcc-4.6
ryoma <e075725@ie.u-ryukyu.ac.jp>
parents:
55
diff
changeset
|
444 |
| 0 | 445 gsi_remove (gsi, false); |
| 446 | |
| 447 /* If we are deleting the PHI node, then we should release the | |
| 448 SSA_NAME node so that it can be reused. */ | |
| 449 release_phi_node (phi); | |
| 450 if (release_lhs_p) | |
| 451 release_ssa_name (gimple_phi_result (phi)); | |
| 452 } | |
| 453 | |
| 454 /* Remove all the phi nodes from BB. */ | |
| 455 | |
| 456 void | |
| 457 remove_phi_nodes (basic_block bb) | |
| 458 { | |
| 111 | 459 gphi_iterator gsi; |
| 0 | 460 |
| 461 for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); ) | |
| 462 remove_phi_node (&gsi, true); | |
| 463 | |
| 464 set_phi_nodes (bb, NULL); | |
| 465 } | |
| 466 | |
| 111 | 467 /* Given PHI, return its RHS if the PHI is a degenerate, otherwise return |
| 468 NULL. */ | |
| 469 | |
| 470 tree | |
| 471 degenerate_phi_result (gphi *phi) | |
| 472 { | |
| 473 tree lhs = gimple_phi_result (phi); | |
| 474 tree val = NULL; | |
| 475 size_t i; | |
| 476 | |
| 477 /* Ignoring arguments which are the same as LHS, if all the remaining | |
| 478 arguments are the same, then the PHI is a degenerate and has the | |
| 479 value of that common argument. */ | |
| 480 for (i = 0; i < gimple_phi_num_args (phi); i++) | |
| 481 { | |
| 482 tree arg = gimple_phi_arg_def (phi, i); | |
| 483 | |
| 484 if (arg == lhs) | |
| 485 continue; | |
| 486 else if (!arg) | |
| 487 break; | |
| 488 else if (!val) | |
| 489 val = arg; | |
| 490 else if (arg == val) | |
| 491 continue; | |
| 492 /* We bring in some of operand_equal_p not only to speed things | |
| 493 up, but also to avoid crashing when dereferencing the type of | |
| 494 a released SSA name. */ | |
| 495 else if (TREE_CODE (val) != TREE_CODE (arg) | |
| 496 || TREE_CODE (val) == SSA_NAME | |
| 497 || !operand_equal_p (arg, val, 0)) | |
| 498 break; | |
| 499 } | |
| 500 return (i == gimple_phi_num_args (phi) ? val : NULL); | |
| 501 } | |
| 502 | |
| 503 /* Set PHI nodes of a basic block BB to SEQ. */ | |
| 504 | |
| 505 void | |
| 506 set_phi_nodes (basic_block bb, gimple_seq seq) | |
| 507 { | |
| 508 gimple_stmt_iterator i; | |
| 509 | |
| 510 gcc_checking_assert (!(bb->flags & BB_RTL)); | |
| 511 bb->il.gimple.phi_nodes = seq; | |
| 512 if (seq) | |
| 513 for (i = gsi_start (seq); !gsi_end_p (i); gsi_next (&i)) | |
| 514 gimple_set_bb (gsi_stmt (i), bb); | |
| 515 } | |
| 516 | |
| 0 | 517 #include "gt-tree-phinodes.h" |