Mercurial > hg > CbC > CbC_gcc
annotate gcc/tree-phinodes.c @ 111:04ced10e8804
gcc 7
author | kono |
---|---|
date | Fri, 27 Oct 2017 22:46:09 +0900 |
parents | f6334be47118 |
children | 84e7813d76e9 |
rev | line source |
---|---|
0 | 1 /* Generic routines for manipulating PHIs |
111 | 2 Copyright (C) 2003-2017 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" |
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 { | |
83 fprintf (stderr, "PHI nodes allocated: %u\n", phi_nodes_created); | |
84 fprintf (stderr, "PHI nodes reused: %u\n", phi_nodes_reused); | |
85 } | |
86 | |
87 /* Allocate a PHI node with at least LEN arguments. If the free list | |
88 happens to contain a PHI node with LEN arguments or more, return | |
89 that one. */ | |
90 | |
111 | 91 static inline gphi * |
0 | 92 allocate_phi_node (size_t len) |
93 { | |
111 | 94 gphi *phi; |
0 | 95 size_t bucket = NUM_BUCKETS - 2; |
111 | 96 size_t size = sizeof (struct gphi) |
0 | 97 + (len - 1) * sizeof (struct phi_arg_d); |
98 | |
99 if (free_phinode_count) | |
100 for (bucket = len - 2; bucket < NUM_BUCKETS - 2; bucket++) | |
101 if (free_phinodes[bucket]) | |
102 break; | |
103 | |
104 /* If our free list has an element, then use it. */ | |
105 if (bucket < NUM_BUCKETS - 2 | |
111 | 106 && gimple_phi_capacity ((*free_phinodes[bucket])[0]) >= len) |
0 | 107 { |
108 free_phinode_count--; | |
111 | 109 phi = as_a <gphi *> (free_phinodes[bucket]->pop ()); |
110 if (free_phinodes[bucket]->is_empty ()) | |
111 vec_free (free_phinodes[bucket]); | |
112 if (GATHER_STATISTICS) | |
113 phi_nodes_reused++; | |
0 | 114 } |
115 else | |
116 { | |
111 | 117 phi = static_cast <gphi *> (ggc_internal_alloc (size)); |
118 if (GATHER_STATISTICS) | |
0 | 119 { |
120 enum gimple_alloc_kind kind = gimple_alloc_kind (GIMPLE_PHI); | |
111 | 121 phi_nodes_created++; |
122 gimple_alloc_counts[(int) kind]++; | |
123 gimple_alloc_sizes[(int) kind] += size; | |
0 | 124 } |
125 } | |
126 | |
127 return phi; | |
128 } | |
129 | |
130 /* Given LEN, the original number of requested PHI arguments, return | |
131 a new, "ideal" length for the PHI node. The "ideal" length rounds | |
132 the total size of the PHI node up to the next power of two bytes. | |
133 | |
134 Rounding up will not result in wasting any memory since the size request | |
135 will be rounded up by the GC system anyway. [ Note this is not entirely | |
136 true since the original length might have fit on one of the special | |
137 GC pages. ] By rounding up, we may avoid the need to reallocate the | |
138 PHI node later if we increase the number of arguments for the PHI. */ | |
139 | |
140 static int | |
141 ideal_phi_node_len (int len) | |
142 { | |
143 size_t size, new_size; | |
144 int log2, new_len; | |
145 | |
146 /* We do not support allocations of less than two PHI argument slots. */ | |
147 if (len < 2) | |
148 len = 2; | |
149 | |
150 /* Compute the number of bytes of the original request. */ | |
111 | 151 size = sizeof (struct gphi) |
0 | 152 + (len - 1) * sizeof (struct phi_arg_d); |
153 | |
154 /* Round it up to the next power of two. */ | |
155 log2 = ceil_log2 (size); | |
156 new_size = 1 << log2; | |
157 | |
158 /* Now compute and return the number of PHI argument slots given an | |
159 ideal size allocation. */ | |
160 new_len = len + (new_size - size) / sizeof (struct phi_arg_d); | |
161 return new_len; | |
162 } | |
163 | |
164 /* Return a PHI node with LEN argument slots for variable VAR. */ | |
165 | |
111 | 166 static gphi * |
0 | 167 make_phi_node (tree var, int len) |
168 { | |
111 | 169 gphi *phi; |
0 | 170 int capacity, i; |
171 | |
172 capacity = ideal_phi_node_len (len); | |
173 | |
174 phi = allocate_phi_node (capacity); | |
175 | |
176 /* We need to clear the entire PHI node, including the argument | |
177 portion, because we represent a "missing PHI argument" by placing | |
178 NULL_TREE in PHI_ARG_DEF. */ | |
111 | 179 memset (phi, 0, (sizeof (struct gphi) |
0 | 180 - sizeof (struct phi_arg_d) |
181 + sizeof (struct phi_arg_d) * len)); | |
111 | 182 phi->code = GIMPLE_PHI; |
183 gimple_init_singleton (phi); | |
184 phi->nargs = len; | |
185 phi->capacity = capacity; | |
186 if (!var) | |
187 ; | |
188 else if (TREE_CODE (var) == SSA_NAME) | |
0 | 189 gimple_phi_set_result (phi, var); |
190 else | |
191 gimple_phi_set_result (phi, make_ssa_name (var, phi)); | |
192 | |
111 | 193 for (i = 0; i < len; i++) |
0 | 194 { |
195 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
|
196 |
77e2b8dfacca
update it from 4.4.3 to 4.5.0
ryoma <e075725@ie.u-ryukyu.ac.jp>
parents:
0
diff
changeset
|
197 gimple_phi_arg_set_location (phi, i, UNKNOWN_LOCATION); |
0 | 198 imm = gimple_phi_arg_imm_use_ptr (phi, i); |
199 imm->use = gimple_phi_arg_def_ptr (phi, i); | |
200 imm->prev = NULL; | |
201 imm->next = NULL; | |
202 imm->loc.stmt = phi; | |
203 } | |
204 | |
205 return phi; | |
206 } | |
207 | |
208 /* We no longer need PHI, release it so that it may be reused. */ | |
209 | |
111 | 210 static void |
211 release_phi_node (gimple *phi) | |
0 | 212 { |
213 size_t bucket; | |
214 size_t len = gimple_phi_capacity (phi); | |
215 size_t x; | |
216 | |
217 for (x = 0; x < gimple_phi_num_args (phi); x++) | |
218 { | |
219 use_operand_p imm; | |
220 imm = gimple_phi_arg_imm_use_ptr (phi, x); | |
221 delink_imm_use (imm); | |
222 } | |
223 | |
224 bucket = len > NUM_BUCKETS - 1 ? NUM_BUCKETS - 1 : len; | |
225 bucket -= 2; | |
111 | 226 vec_safe_push (free_phinodes[bucket], phi); |
0 | 227 free_phinode_count++; |
228 } | |
229 | |
230 | |
231 /* Resize an existing PHI node. The only way is up. Return the | |
232 possibly relocated phi. */ | |
233 | |
111 | 234 static gphi * |
235 resize_phi_node (gphi *phi, size_t len) | |
0 | 236 { |
237 size_t old_size, i; | |
111 | 238 gphi *new_phi; |
0 | 239 |
111 | 240 gcc_assert (len > gimple_phi_capacity (phi)); |
0 | 241 |
242 /* The garbage collector will not look at the PHI node beyond the | |
243 first PHI_NUM_ARGS elements. Therefore, all we have to copy is a | |
244 portion of the PHI node currently in use. */ | |
111 | 245 old_size = sizeof (struct gphi) |
246 + (gimple_phi_num_args (phi) - 1) * sizeof (struct phi_arg_d); | |
0 | 247 |
248 new_phi = allocate_phi_node (len); | |
249 | |
111 | 250 memcpy (new_phi, phi, old_size); |
251 memset ((char *)new_phi + old_size, 0, | |
252 (sizeof (struct gphi) | |
253 - sizeof (struct phi_arg_d) | |
254 + sizeof (struct phi_arg_d) * len) - old_size); | |
0 | 255 |
256 for (i = 0; i < gimple_phi_num_args (new_phi); i++) | |
257 { | |
258 use_operand_p imm, old_imm; | |
259 imm = gimple_phi_arg_imm_use_ptr (new_phi, i); | |
111 | 260 old_imm = gimple_phi_arg_imm_use_ptr (phi, i); |
0 | 261 imm->use = gimple_phi_arg_def_ptr (new_phi, i); |
262 relink_imm_use_stmt (imm, old_imm, new_phi); | |
263 } | |
264 | |
111 | 265 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
|
266 |
111 | 267 return new_phi; |
0 | 268 } |
269 | |
270 /* Reserve PHI arguments for a new edge to basic block BB. */ | |
271 | |
272 void | |
273 reserve_phi_args_for_new_edge (basic_block bb) | |
274 { | |
275 size_t len = EDGE_COUNT (bb->preds); | |
276 size_t cap = ideal_phi_node_len (len + 4); | |
111 | 277 gphi_iterator gsi; |
0 | 278 |
279 for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi)) | |
280 { | |
111 | 281 gphi *stmt = gsi.phi (); |
0 | 282 |
111 | 283 if (len > gimple_phi_capacity (stmt)) |
0 | 284 { |
111 | 285 gphi *new_phi = resize_phi_node (stmt, cap); |
0 | 286 |
287 /* The result of the PHI is defined by this PHI node. */ | |
111 | 288 SSA_NAME_DEF_STMT (gimple_phi_result (new_phi)) = new_phi; |
289 gsi_set_stmt (&gsi, new_phi); | |
0 | 290 |
111 | 291 release_phi_node (stmt); |
292 stmt = new_phi; | |
0 | 293 } |
294 | |
111 | 295 stmt->nargs++; |
296 | |
0 | 297 /* We represent a "missing PHI argument" by placing NULL_TREE in |
298 the corresponding slot. If PHI arguments were added | |
299 immediately after an edge is created, this zeroing would not | |
300 be necessary, but unfortunately this is not the case. For | |
301 example, the loop optimizer duplicates several basic blocks, | |
302 redirects edges, and then fixes up PHI arguments later in | |
303 batch. */ | |
111 | 304 use_operand_p imm = gimple_phi_arg_imm_use_ptr (stmt, len - 1); |
305 imm->use = gimple_phi_arg_def_ptr (stmt, len - 1); | |
306 imm->prev = NULL; | |
307 imm->next = NULL; | |
308 imm->loc.stmt = stmt; | |
309 SET_PHI_ARG_DEF (stmt, len - 1, NULL_TREE); | |
310 gimple_phi_arg_set_location (stmt, len - 1, UNKNOWN_LOCATION); | |
0 | 311 } |
312 } | |
313 | |
314 /* Adds PHI to BB. */ | |
315 | |
55
77e2b8dfacca
update it from 4.4.3 to 4.5.0
ryoma <e075725@ie.u-ryukyu.ac.jp>
parents:
0
diff
changeset
|
316 void |
111 | 317 add_phi_node_to_bb (gphi *phi, basic_block bb) |
0 | 318 { |
111 | 319 gimple_seq seq = phi_nodes (bb); |
0 | 320 /* Add the new PHI node to the list of PHI nodes for block BB. */ |
111 | 321 if (seq == NULL) |
322 set_phi_nodes (bb, gimple_seq_alloc_with_stmt (phi)); | |
323 else | |
324 { | |
325 gimple_seq_add_stmt (&seq, phi); | |
326 gcc_assert (seq == phi_nodes (bb)); | |
327 } | |
0 | 328 |
329 /* Associate BB to the PHI node. */ | |
330 gimple_set_bb (phi, bb); | |
331 | |
332 } | |
333 | |
334 /* Create a new PHI node for variable VAR at basic block BB. */ | |
335 | |
111 | 336 gphi * |
0 | 337 create_phi_node (tree var, basic_block bb) |
338 { | |
111 | 339 gphi *phi = make_phi_node (var, EDGE_COUNT (bb->preds)); |
0 | 340 |
341 add_phi_node_to_bb (phi, bb); | |
342 return phi; | |
343 } | |
344 | |
345 | |
346 /* Add a new argument to PHI node PHI. DEF is the incoming reaching | |
347 definition and E is the edge through which DEF reaches PHI. The new | |
348 argument is added at the end of the argument list. | |
349 If PHI has reached its maximum capacity, add a few slots. In this case, | |
350 PHI points to the reallocated phi node when we return. */ | |
351 | |
352 void | |
111 | 353 add_phi_arg (gphi *phi, tree def, edge e, source_location locus) |
0 | 354 { |
355 basic_block bb = e->dest; | |
356 | |
357 gcc_assert (bb == gimple_bb (phi)); | |
358 | |
359 /* We resize PHI nodes upon edge creation. We should always have | |
360 enough room at this point. */ | |
361 gcc_assert (gimple_phi_num_args (phi) <= gimple_phi_capacity (phi)); | |
362 | |
363 /* We resize PHI nodes upon edge creation. We should always have | |
364 enough room at this point. */ | |
365 gcc_assert (e->dest_idx < gimple_phi_num_args (phi)); | |
366 | |
367 /* Copy propagation needs to know what object occur in abnormal | |
368 PHI nodes. This is a convenient place to record such information. */ | |
369 if (e->flags & EDGE_ABNORMAL) | |
370 { | |
371 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (def) = 1; | |
372 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (PHI_RESULT (phi)) = 1; | |
373 } | |
374 | |
375 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
|
376 gimple_phi_arg_set_location (phi, e->dest_idx, locus); |
0 | 377 } |
378 | |
379 | |
380 /* Remove the Ith argument from PHI's argument list. This routine | |
381 implements removal by swapping the last alternative with the | |
382 alternative we want to delete and then shrinking the vector, which | |
383 is consistent with how we remove an edge from the edge vector. */ | |
384 | |
385 static void | |
111 | 386 remove_phi_arg_num (gphi *phi, int i) |
0 | 387 { |
388 int num_elem = gimple_phi_num_args (phi); | |
389 | |
390 gcc_assert (i < num_elem); | |
391 | |
392 /* Delink the item which is being removed. */ | |
393 delink_imm_use (gimple_phi_arg_imm_use_ptr (phi, i)); | |
394 | |
395 /* If it is not the last element, move the last element | |
396 to the element we want to delete, resetting all the links. */ | |
397 if (i != num_elem - 1) | |
398 { | |
399 use_operand_p old_p, new_p; | |
400 old_p = gimple_phi_arg_imm_use_ptr (phi, num_elem - 1); | |
401 new_p = gimple_phi_arg_imm_use_ptr (phi, i); | |
402 /* Set use on new node, and link into last element's place. */ | |
403 *(new_p->use) = *(old_p->use); | |
404 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
|
405 /* 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
|
406 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
|
407 gimple_phi_arg_location (phi, num_elem - 1)); |
0 | 408 } |
409 | |
410 /* Shrink the vector and return. Note that we do not have to clear | |
411 PHI_ARG_DEF because the garbage collector will not look at those | |
412 elements beyond the first PHI_NUM_ARGS elements of the array. */ | |
111 | 413 phi->nargs--; |
0 | 414 } |
415 | |
416 | |
417 /* Remove all PHI arguments associated with edge E. */ | |
418 | |
419 void | |
420 remove_phi_args (edge e) | |
421 { | |
111 | 422 gphi_iterator gsi; |
0 | 423 |
424 for (gsi = gsi_start_phis (e->dest); !gsi_end_p (gsi); gsi_next (&gsi)) | |
111 | 425 remove_phi_arg_num (gsi.phi (), |
426 e->dest_idx); | |
0 | 427 } |
428 | |
429 | |
430 /* Remove the PHI node pointed-to by iterator GSI from basic block BB. After | |
431 removal, iterator GSI is updated to point to the next PHI node in the | |
432 sequence. If RELEASE_LHS_P is true, the LHS of this PHI node is released | |
433 into the free pool of SSA names. */ | |
434 | |
435 void | |
436 remove_phi_node (gimple_stmt_iterator *gsi, bool release_lhs_p) | |
437 { | |
111 | 438 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
|
439 |
b7f97abdc517
update gcc from gcc-4.5.0 to gcc-4.6
ryoma <e075725@ie.u-ryukyu.ac.jp>
parents:
55
diff
changeset
|
440 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
|
441 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
|
442 |
0 | 443 gsi_remove (gsi, false); |
444 | |
445 /* If we are deleting the PHI node, then we should release the | |
446 SSA_NAME node so that it can be reused. */ | |
447 release_phi_node (phi); | |
448 if (release_lhs_p) | |
449 release_ssa_name (gimple_phi_result (phi)); | |
450 } | |
451 | |
452 /* Remove all the phi nodes from BB. */ | |
453 | |
454 void | |
455 remove_phi_nodes (basic_block bb) | |
456 { | |
111 | 457 gphi_iterator gsi; |
0 | 458 |
459 for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); ) | |
460 remove_phi_node (&gsi, true); | |
461 | |
462 set_phi_nodes (bb, NULL); | |
463 } | |
464 | |
111 | 465 /* Given PHI, return its RHS if the PHI is a degenerate, otherwise return |
466 NULL. */ | |
467 | |
468 tree | |
469 degenerate_phi_result (gphi *phi) | |
470 { | |
471 tree lhs = gimple_phi_result (phi); | |
472 tree val = NULL; | |
473 size_t i; | |
474 | |
475 /* Ignoring arguments which are the same as LHS, if all the remaining | |
476 arguments are the same, then the PHI is a degenerate and has the | |
477 value of that common argument. */ | |
478 for (i = 0; i < gimple_phi_num_args (phi); i++) | |
479 { | |
480 tree arg = gimple_phi_arg_def (phi, i); | |
481 | |
482 if (arg == lhs) | |
483 continue; | |
484 else if (!arg) | |
485 break; | |
486 else if (!val) | |
487 val = arg; | |
488 else if (arg == val) | |
489 continue; | |
490 /* We bring in some of operand_equal_p not only to speed things | |
491 up, but also to avoid crashing when dereferencing the type of | |
492 a released SSA name. */ | |
493 else if (TREE_CODE (val) != TREE_CODE (arg) | |
494 || TREE_CODE (val) == SSA_NAME | |
495 || !operand_equal_p (arg, val, 0)) | |
496 break; | |
497 } | |
498 return (i == gimple_phi_num_args (phi) ? val : NULL); | |
499 } | |
500 | |
501 /* Set PHI nodes of a basic block BB to SEQ. */ | |
502 | |
503 void | |
504 set_phi_nodes (basic_block bb, gimple_seq seq) | |
505 { | |
506 gimple_stmt_iterator i; | |
507 | |
508 gcc_checking_assert (!(bb->flags & BB_RTL)); | |
509 bb->il.gimple.phi_nodes = seq; | |
510 if (seq) | |
511 for (i = gsi_start (seq); !gsi_end_p (i); gsi_next (&i)) | |
512 gimple_set_bb (gsi_stmt (i), bb); | |
513 } | |
514 | |
0 | 515 #include "gt-tree-phinodes.h" |