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bdf50f60 | 1 | /* Routines for performing Temporary Expression Replacement (TER) in SSA trees. |
d353bf18 | 2 | Copyright (C) 2003-2015 Free Software Foundation, Inc. |
bdf50f60 | 3 | Contributed by Andrew MacLeod <amacleod@redhat.com> |
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 | |
8c4c00c1 | 9 | the Free Software Foundation; either version 3, or (at your option) |
bdf50f60 | 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 | |
8c4c00c1 | 18 | along with GCC; see the file COPYING3. If not see |
19 | <http://www.gnu.org/licenses/>. */ | |
bdf50f60 | 20 | |
21 | ||
22 | #include "config.h" | |
23 | #include "system.h" | |
24 | #include "coretypes.h" | |
25 | #include "tm.h" | |
b20a8bb4 | 26 | #include "hash-set.h" |
b20a8bb4 | 27 | #include "vec.h" |
b20a8bb4 | 28 | #include "input.h" |
29 | #include "alias.h" | |
30 | #include "symtab.h" | |
b20a8bb4 | 31 | #include "inchash.h" |
bdf50f60 | 32 | #include "tree.h" |
b20a8bb4 | 33 | #include "fold-const.h" |
ce084dfc | 34 | #include "gimple-pretty-print.h" |
bdf50f60 | 35 | #include "bitmap.h" |
94ea8568 | 36 | #include "predict.h" |
37 | #include "vec.h" | |
38 | #include "hashtab.h" | |
39 | #include "hash-set.h" | |
94ea8568 | 40 | #include "hard-reg-set.h" |
41 | #include "input.h" | |
42 | #include "function.h" | |
43 | #include "dominance.h" | |
44 | #include "cfg.h" | |
bc61cadb | 45 | #include "basic-block.h" |
46 | #include "tree-ssa-alias.h" | |
47 | #include "internal-fn.h" | |
48 | #include "gimple-expr.h" | |
49 | #include "is-a.h" | |
073c1fd5 | 50 | #include "gimple.h" |
dcf1a1ec | 51 | #include "gimple-iterator.h" |
073c1fd5 | 52 | #include "gimple-ssa.h" |
53 | #include "tree-phinodes.h" | |
54 | #include "ssa-iterators.h" | |
9ed99284 | 55 | #include "stringpool.h" |
073c1fd5 | 56 | #include "tree-ssanames.h" |
b9ed1410 | 57 | #include "dumpfile.h" |
b23fb4cb | 58 | #include "tree-ssa-live.h" |
59 | #include "tree-ssa-ter.h" | |
f7373a91 | 60 | #include "tree-outof-ssa.h" |
bff4202c | 61 | #include "flags.h" |
5b26a9e3 | 62 | #include "gimple-walk.h" |
bdf50f60 | 63 | |
64 | ||
65 | /* Temporary Expression Replacement (TER) | |
66 | ||
67 | Replace SSA version variables during out-of-ssa with their defining | |
48e1416a | 68 | expression if there is only one use of the variable. |
bdf50f60 | 69 | |
70 | This pass is required in order for the RTL expansion pass to see larger | |
71 | chunks of code. This allows it to make better choices on RTL pattern | |
72 | selection. When expand is rewritten and merged with out-of-ssa, and | |
48e1416a | 73 | understands SSA, this should be eliminated. |
bdf50f60 | 74 | |
75 | A pass is made through the function, one block at a time. No cross block | |
76 | information is tracked. | |
77 | ||
78 | Variables which only have one use, and whose defining stmt is considered | |
f7373a91 | 79 | a replaceable expression (see ssa_is_replaceable_p) are tracked to see whether |
48e1416a | 80 | they can be replaced at their use location. |
81 | ||
bdf50f60 | 82 | n_12 = C * 10 |
83 | a_2 = b_5 + 6 | |
84 | v_9 = a_2 * n_12 | |
85 | ||
86 | if there are the only use of n_12 and a_2, TER will substitute in their | |
87 | expressions in v_9, and end up with: | |
88 | ||
89 | v_9 = (b_5 + 6) * (C * 10) | |
90 | ||
91 | which will then have the ssa_name assigned to regular variables, and the | |
f0b5f617 | 92 | resulting code which will be passed to the expander looks something like: |
bdf50f60 | 93 | |
94 | v = (b + 6) * (C * 10) | |
95 | ||
48e1416a | 96 | |
97 | This requires ensuring that none of the variables used by the expression | |
98 | change between the def point and where it is used. Furthermore, if any | |
99 | of the ssa_names used in this expression are themselves replaceable, we | |
100 | have to ensure none of that expressions' arguments change either. | |
101 | Although SSA_NAMES themselves don't change, this pass is performed after | |
102 | coalescing has coalesced different SSA_NAMES together, so there could be a | |
bdf50f60 | 103 | definition of an SSA_NAME which is coalesced with a use that causes a |
f0b5f617 | 104 | problem, i.e., |
48e1416a | 105 | |
bdf50f60 | 106 | PHI b_5 = <b_8(2), b_14(1)> |
107 | <...> | |
108 | a_2 = b_5 + 6 | |
109 | b_8 = c_4 + 4 | |
110 | v_9 = a_2 * n_12 | |
111 | <...> | |
112 | ||
7920eed5 | 113 | If b_5, b_8 and b_14 are all coalesced together... |
bdf50f60 | 114 | The expression b_5 + 6 CANNOT replace the use in the statement defining v_9 |
115 | because b_8 is in fact killing the value of b_5 since they share a partition | |
7920eed5 | 116 | and will be assigned the same memory or register location. |
48e1416a | 117 | |
bdf50f60 | 118 | TER implements this but stepping through the instructions in a block and |
7920eed5 | 119 | tracking potential expressions for replacement, and the partitions they are |
bdf50f60 | 120 | dependent on. Expressions are represented by the SSA_NAME_VERSION of the |
75a70cf9 | 121 | DEF on the LHS of a GIMPLE_ASSIGN and the expression is the RHS. |
bdf50f60 | 122 | |
123 | When a stmt is determined to be a possible replacement expression, the | |
124 | following steps are taken: | |
125 | ||
48e1416a | 126 | EXPR_DECL_UID bitmap is allocated and set to the base variable UID of the |
127 | def and any uses in the expression. non-NULL means the expression is being | |
bdf50f60 | 128 | tracked. The UID's themselves are used to prevent TER substitution into |
f0b5f617 | 129 | accumulating sequences, i.e., |
130 | ||
bdf50f60 | 131 | x = x + y |
132 | x = x + z | |
133 | x = x + w | |
134 | etc. | |
135 | this can result in very large expressions which don't accomplish anything | |
48e1416a | 136 | see PR tree-optimization/17549. |
bdf50f60 | 137 | |
48e1416a | 138 | PARTITION_DEPENDENCIES is another bitmap array, and it has a bit set for any |
bdf50f60 | 139 | partition which is used in the expression. This is primarily used to remove |
140 | an expression from the partition kill lists when a decision is made whether | |
141 | to replace it or not. This is indexed by ssa version number as well, and | |
142 | indicates a partition number. virtual operands are not tracked individually, | |
7920eed5 | 143 | but they are summarized by an artificial partition called VIRTUAL_PARTITION. |
144 | This means a MAY or MUST def will kill *ALL* expressions that are dependent | |
bdf50f60 | 145 | on a virtual operand. |
48e1416a | 146 | Note that the EXPR_DECL_UID and this bitmap represent very similar |
bdf50f60 | 147 | information, but the info in one is not easy to obtain from the other. |
148 | ||
149 | KILL_LIST is yet another bitmap array, this time it is indexed by partition | |
48e1416a | 150 | number, and represents a list of active expressions which will will no |
bdf50f60 | 151 | longer be valid if a definition into this partition takes place. |
152 | ||
153 | PARTITION_IN_USE is simply a bitmap which is used to track which partitions | |
48e1416a | 154 | currently have something in their kill list. This is used at the end of |
bdf50f60 | 155 | a block to clear out the KILL_LIST bitmaps at the end of each block. |
156 | ||
48e1416a | 157 | NEW_REPLACEABLE_DEPENDENCIES is used as a temporary place to store |
f0b5f617 | 158 | dependencies which will be reused by the current definition. All the uses |
bdf50f60 | 159 | on an expression are processed before anything else is done. If a use is |
160 | determined to be a replaceable expression AND the current stmt is also going | |
161 | to be replaceable, all the dependencies of this replaceable use will be | |
162 | picked up by the current stmt's expression. Rather than recreate them, they | |
163 | are simply copied here and then copied into the new expression when it is | |
164 | processed. | |
165 | ||
166 | a_2 = b_5 + 6 | |
167 | v_8 = a_2 + c_4 | |
168 | ||
48e1416a | 169 | a_2's expression 'b_5 + 6' is determined to be replaceable at the use |
bdf50f60 | 170 | location. It is dependent on the partition 'b_5' is in. This is cached into |
f0b5f617 | 171 | the NEW_REPLACEABLE_DEPENDENCIES bitmap, and when v_8 is examined for |
172 | replaceability, it is a candidate, and it is dependent on the partition | |
bdf50f60 | 173 | b_5 is in *NOT* a_2, as well as c_4's partition. |
174 | ||
175 | if v_8 is also replaceable: | |
176 | ||
177 | x_9 = v_8 * 5 | |
178 | ||
179 | x_9 is dependent on partitions b_5, and c_4 | |
48e1416a | 180 | |
181 | if a statement is found which has either of those partitions written to | |
bdf50f60 | 182 | before x_9 is used, then x_9 itself is NOT replaceable. */ |
183 | ||
184 | ||
185 | /* Temporary Expression Replacement (TER) table information. */ | |
186 | ||
48e1416a | 187 | typedef struct temp_expr_table_d |
bdf50f60 | 188 | { |
189 | var_map map; | |
190 | bitmap *partition_dependencies; /* Partitions expr is dependent on. */ | |
dfdbf3fd | 191 | bitmap replaceable_expressions; /* Replacement expression table. */ |
bdf50f60 | 192 | bitmap *expr_decl_uids; /* Base uids of exprs. */ |
193 | bitmap *kill_list; /* Expr's killed by a partition. */ | |
7920eed5 | 194 | int virtual_partition; /* Pseudo partition for virtual ops. */ |
195 | bitmap partition_in_use; /* Partitions with kill entries. */ | |
bdf50f60 | 196 | bitmap new_replaceable_dependencies; /* Holding place for pending dep's. */ |
197 | int *num_in_part; /* # of ssa_names in a partition. */ | |
b029d3b7 | 198 | int *call_cnt; /* Call count at definition. */ |
bdf50f60 | 199 | } *temp_expr_table_p; |
200 | ||
4fb5e5ca | 201 | /* Used to indicate a dependency on VDEFs. */ |
bdf50f60 | 202 | #define VIRTUAL_PARTITION(table) (table->virtual_partition) |
203 | ||
4fb07d00 | 204 | /* A place for the many, many bitmaps we create. */ |
205 | static bitmap_obstack ter_bitmap_obstack; | |
206 | ||
bdf50f60 | 207 | #ifdef ENABLE_CHECKING |
208 | extern void debug_ter (FILE *, temp_expr_table_p); | |
209 | #endif | |
210 | ||
211 | ||
212 | /* Create a new TER table for MAP. */ | |
213 | ||
214 | static temp_expr_table_p | |
215 | new_temp_expr_table (var_map map) | |
216 | { | |
217 | temp_expr_table_p t; | |
218 | unsigned x; | |
219 | ||
220 | t = XNEW (struct temp_expr_table_d); | |
221 | t->map = map; | |
222 | ||
223 | t->partition_dependencies = XCNEWVEC (bitmap, num_ssa_names + 1); | |
224 | t->expr_decl_uids = XCNEWVEC (bitmap, num_ssa_names + 1); | |
225 | t->kill_list = XCNEWVEC (bitmap, num_var_partitions (map) + 1); | |
226 | ||
4fb07d00 | 227 | t->partition_in_use = BITMAP_ALLOC (&ter_bitmap_obstack); |
bdf50f60 | 228 | |
229 | t->virtual_partition = num_var_partitions (map); | |
4fb07d00 | 230 | t->new_replaceable_dependencies = BITMAP_ALLOC (&ter_bitmap_obstack); |
bdf50f60 | 231 | |
232 | t->replaceable_expressions = NULL; | |
233 | t->num_in_part = XCNEWVEC (int, num_var_partitions (map)); | |
234 | for (x = 1; x < num_ssa_names; x++) | |
235 | { | |
236 | int p; | |
237 | tree name = ssa_name (x); | |
238 | if (!name) | |
239 | continue; | |
240 | p = var_to_partition (map, name); | |
241 | if (p != NO_PARTITION) | |
242 | t->num_in_part[p]++; | |
243 | } | |
b029d3b7 | 244 | t->call_cnt = XCNEWVEC (int, num_ssa_names + 1); |
bdf50f60 | 245 | |
246 | return t; | |
247 | } | |
248 | ||
249 | ||
48e1416a | 250 | /* Free TER table T. If there are valid replacements, return the expression |
bdf50f60 | 251 | vector. */ |
252 | ||
dfdbf3fd | 253 | static bitmap |
bdf50f60 | 254 | free_temp_expr_table (temp_expr_table_p t) |
255 | { | |
dfdbf3fd | 256 | bitmap ret = NULL; |
bdf50f60 | 257 | |
258 | #ifdef ENABLE_CHECKING | |
259 | unsigned x; | |
260 | for (x = 0; x <= num_var_partitions (t->map); x++) | |
261 | gcc_assert (!t->kill_list[x]); | |
0d3f8fd5 | 262 | for (x = 0; x < num_ssa_names; x++) |
464cc29a | 263 | { |
264 | gcc_assert (t->expr_decl_uids[x] == NULL); | |
265 | gcc_assert (t->partition_dependencies[x] == NULL); | |
266 | } | |
bdf50f60 | 267 | #endif |
268 | ||
269 | BITMAP_FREE (t->partition_in_use); | |
c2df357d | 270 | BITMAP_FREE (t->new_replaceable_dependencies); |
bdf50f60 | 271 | |
bdf50f60 | 272 | free (t->expr_decl_uids); |
bdf50f60 | 273 | free (t->kill_list); |
274 | free (t->partition_dependencies); | |
c2df357d | 275 | free (t->num_in_part); |
b029d3b7 | 276 | free (t->call_cnt); |
bdf50f60 | 277 | |
278 | if (t->replaceable_expressions) | |
279 | ret = t->replaceable_expressions; | |
280 | ||
281 | free (t); | |
282 | return ret; | |
283 | } | |
284 | ||
285 | ||
286 | /* Return TRUE if VERSION is to be replaced by an expression in TAB. */ | |
287 | ||
288 | static inline bool | |
289 | version_to_be_replaced_p (temp_expr_table_p tab, int version) | |
290 | { | |
291 | if (!tab->replaceable_expressions) | |
292 | return false; | |
dfdbf3fd | 293 | return bitmap_bit_p (tab->replaceable_expressions, version); |
bdf50f60 | 294 | } |
295 | ||
296 | ||
48e1416a | 297 | /* Add partition P to the list if partitions VERSION is dependent on. TAB is |
bdf50f60 | 298 | the expression table */ |
299 | ||
300 | static inline void | |
301 | make_dependent_on_partition (temp_expr_table_p tab, int version, int p) | |
302 | { | |
303 | if (!tab->partition_dependencies[version]) | |
4fb07d00 | 304 | tab->partition_dependencies[version] = BITMAP_ALLOC (&ter_bitmap_obstack); |
bdf50f60 | 305 | |
306 | bitmap_set_bit (tab->partition_dependencies[version], p); | |
307 | } | |
308 | ||
309 | ||
310 | /* Add VER to the kill list for P. TAB is the expression table */ | |
311 | ||
312 | static inline void | |
313 | add_to_partition_kill_list (temp_expr_table_p tab, int p, int ver) | |
314 | { | |
315 | if (!tab->kill_list[p]) | |
316 | { | |
4fb07d00 | 317 | tab->kill_list[p] = BITMAP_ALLOC (&ter_bitmap_obstack); |
bdf50f60 | 318 | bitmap_set_bit (tab->partition_in_use, p); |
319 | } | |
320 | bitmap_set_bit (tab->kill_list[p], ver); | |
321 | } | |
322 | ||
323 | ||
48e1416a | 324 | /* Remove VER from the partition kill list for P. TAB is the expression |
bdf50f60 | 325 | table. */ |
326 | ||
48e1416a | 327 | static inline void |
bdf50f60 | 328 | remove_from_partition_kill_list (temp_expr_table_p tab, int p, int version) |
329 | { | |
1b4345f7 | 330 | gcc_checking_assert (tab->kill_list[p]); |
bdf50f60 | 331 | bitmap_clear_bit (tab->kill_list[p], version); |
332 | if (bitmap_empty_p (tab->kill_list[p])) | |
333 | { | |
334 | bitmap_clear_bit (tab->partition_in_use, p); | |
335 | BITMAP_FREE (tab->kill_list[p]); | |
336 | } | |
337 | } | |
338 | ||
339 | ||
48e1416a | 340 | /* Add a dependency between the def of ssa VERSION and VAR. If VAR is |
341 | replaceable by an expression, add a dependence each of the elements of the | |
bdf50f60 | 342 | expression. These are contained in the new_replaceable list. TAB is the |
343 | expression table. */ | |
344 | ||
345 | static void | |
346 | add_dependence (temp_expr_table_p tab, int version, tree var) | |
347 | { | |
348 | int i; | |
349 | bitmap_iterator bi; | |
350 | unsigned x; | |
351 | ||
352 | i = SSA_NAME_VERSION (var); | |
353 | if (version_to_be_replaced_p (tab, i)) | |
354 | { | |
355 | if (!bitmap_empty_p (tab->new_replaceable_dependencies)) | |
356 | { | |
48e1416a | 357 | /* Version will now be killed by a write to any partition the |
bdf50f60 | 358 | substituted expression would have been killed by. */ |
359 | EXECUTE_IF_SET_IN_BITMAP (tab->new_replaceable_dependencies, 0, x, bi) | |
360 | add_to_partition_kill_list (tab, x, version); | |
361 | ||
48e1416a | 362 | /* Rather than set partition_dependencies and in_use lists bit by |
bdf50f60 | 363 | bit, simply OR in the new_replaceable_dependencies bits. */ |
364 | if (!tab->partition_dependencies[version]) | |
4fb07d00 | 365 | tab->partition_dependencies[version] = |
366 | BITMAP_ALLOC (&ter_bitmap_obstack); | |
48e1416a | 367 | bitmap_ior_into (tab->partition_dependencies[version], |
bdf50f60 | 368 | tab->new_replaceable_dependencies); |
48e1416a | 369 | bitmap_ior_into (tab->partition_in_use, |
bdf50f60 | 370 | tab->new_replaceable_dependencies); |
371 | /* It is only necessary to add these once. */ | |
372 | bitmap_clear (tab->new_replaceable_dependencies); | |
373 | } | |
374 | } | |
375 | else | |
376 | { | |
377 | i = var_to_partition (tab->map, var); | |
1b4345f7 | 378 | gcc_checking_assert (i != NO_PARTITION); |
379 | gcc_checking_assert (tab->num_in_part[i] != 0); | |
bdf50f60 | 380 | /* Only dependencies on ssa_names which are coalesced with something need |
381 | to be tracked. Partitions with containing only a single SSA_NAME | |
382 | *cannot* have their value changed. */ | |
383 | if (tab->num_in_part[i] > 1) | |
384 | { | |
385 | add_to_partition_kill_list (tab, i, version); | |
386 | make_dependent_on_partition (tab, version, i); | |
387 | } | |
388 | } | |
389 | } | |
390 | ||
391 | ||
48e1416a | 392 | /* This function will remove the expression for VERSION from replacement |
393 | consideration in table TAB. If FREE_EXPR is true, then remove the | |
bdf50f60 | 394 | expression from consideration as well by freeing the decl uid bitmap. */ |
395 | ||
396 | static void | |
397 | finished_with_expr (temp_expr_table_p tab, int version, bool free_expr) | |
398 | { | |
399 | unsigned i; | |
400 | bitmap_iterator bi; | |
401 | ||
402 | /* Remove this expression from its dependent lists. The partition dependence | |
9d75589a | 403 | list is retained and transferred later to whomever uses this version. */ |
bdf50f60 | 404 | if (tab->partition_dependencies[version]) |
405 | { | |
406 | EXECUTE_IF_SET_IN_BITMAP (tab->partition_dependencies[version], 0, i, bi) | |
407 | remove_from_partition_kill_list (tab, i, version); | |
408 | BITMAP_FREE (tab->partition_dependencies[version]); | |
409 | } | |
410 | if (free_expr) | |
411 | BITMAP_FREE (tab->expr_decl_uids[version]); | |
412 | } | |
413 | ||
414 | ||
f7373a91 | 415 | /* Return TRUE if expression STMT is suitable for replacement. |
416 | In addition to ssa_is_replaceable_p, require the same bb, and for -O0 | |
417 | same locus and same BLOCK), Considers memory loads as replaceable if aliasing | |
418 | is available. */ | |
419 | ||
420 | static inline bool | |
421 | ter_is_replaceable_p (gimple stmt) | |
422 | { | |
423 | ||
424 | if (ssa_is_replaceable_p (stmt)) | |
425 | { | |
426 | use_operand_p use_p; | |
427 | tree def; | |
428 | gimple use_stmt; | |
429 | location_t locus1, locus2; | |
430 | tree block1, block2; | |
431 | ||
432 | /* Only consider definitions which have a single use. ssa_is_replaceable_p | |
433 | already performed this check, but the use stmt pointer is required for | |
434 | further checks. */ | |
435 | def = SINGLE_SSA_TREE_OPERAND (stmt, SSA_OP_DEF); | |
436 | if (!single_imm_use (def, &use_p, &use_stmt)) | |
437 | return false; | |
438 | ||
439 | /* If the use isn't in this block, it wont be replaced either. */ | |
440 | if (gimple_bb (use_stmt) != gimple_bb (stmt)) | |
441 | return false; | |
442 | ||
443 | locus1 = gimple_location (stmt); | |
444 | block1 = LOCATION_BLOCK (locus1); | |
445 | locus1 = LOCATION_LOCUS (locus1); | |
446 | ||
1a91d914 | 447 | if (gphi *phi = dyn_cast <gphi *> (use_stmt)) |
448 | locus2 = gimple_phi_arg_location (phi, | |
f7373a91 | 449 | PHI_ARG_INDEX_FROM_USE (use_p)); |
450 | else | |
451 | locus2 = gimple_location (use_stmt); | |
452 | block2 = LOCATION_BLOCK (locus2); | |
453 | locus2 = LOCATION_LOCUS (locus2); | |
454 | ||
455 | if ((!optimize || optimize_debug) | |
456 | && ((locus1 != UNKNOWN_LOCATION && locus1 != locus2) | |
457 | || (block1 != NULL_TREE && block1 != block2))) | |
458 | return false; | |
459 | ||
f7373a91 | 460 | return true; |
461 | } | |
462 | return false; | |
463 | } | |
464 | ||
465 | ||
0b7780cd | 466 | /* Create an expression entry for a replaceable expression. */ |
bdf50f60 | 467 | |
48e1416a | 468 | static void |
b029d3b7 | 469 | process_replaceable (temp_expr_table_p tab, gimple stmt, int call_cnt) |
bdf50f60 | 470 | { |
471 | tree var, def, basevar; | |
472 | int version; | |
473 | ssa_op_iter iter; | |
474 | bitmap def_vars, use_vars; | |
475 | ||
f7373a91 | 476 | gcc_checking_assert (ter_is_replaceable_p (stmt)); |
bdf50f60 | 477 | |
478 | def = SINGLE_SSA_TREE_OPERAND (stmt, SSA_OP_DEF); | |
479 | version = SSA_NAME_VERSION (def); | |
4fb07d00 | 480 | def_vars = BITMAP_ALLOC (&ter_bitmap_obstack); |
bdf50f60 | 481 | |
ec11736b | 482 | basevar = SSA_NAME_VAR (def); |
483 | if (basevar) | |
484 | bitmap_set_bit (def_vars, DECL_UID (basevar)); | |
bdf50f60 | 485 | |
486 | /* Add this expression to the dependency list for each use partition. */ | |
487 | FOR_EACH_SSA_TREE_OPERAND (var, stmt, iter, SSA_OP_USE) | |
488 | { | |
489 | int var_version = SSA_NAME_VERSION (var); | |
490 | ||
491 | use_vars = tab->expr_decl_uids[var_version]; | |
492 | add_dependence (tab, version, var); | |
493 | if (use_vars) | |
494 | { | |
495 | bitmap_ior_into (def_vars, use_vars); | |
496 | BITMAP_FREE (tab->expr_decl_uids[var_version]); | |
497 | } | |
ec11736b | 498 | else if (SSA_NAME_VAR (var)) |
bdf50f60 | 499 | bitmap_set_bit (def_vars, DECL_UID (SSA_NAME_VAR (var))); |
500 | } | |
501 | tab->expr_decl_uids[version] = def_vars; | |
502 | ||
503 | /* If there are VUSES, add a dependence on virtual defs. */ | |
dd277d48 | 504 | if (gimple_vuse (stmt)) |
bdf50f60 | 505 | { |
506 | make_dependent_on_partition (tab, version, VIRTUAL_PARTITION (tab)); | |
507 | add_to_partition_kill_list (tab, VIRTUAL_PARTITION (tab), version); | |
508 | } | |
b029d3b7 | 509 | |
510 | tab->call_cnt[version] = call_cnt; | |
bdf50f60 | 511 | } |
512 | ||
513 | ||
514 | /* This function removes any expression in TAB which is dependent on PARTITION | |
515 | from consideration, making it not replaceable. */ | |
516 | ||
517 | static inline void | |
518 | kill_expr (temp_expr_table_p tab, int partition) | |
519 | { | |
520 | unsigned version; | |
521 | ||
48e1416a | 522 | /* Mark every active expr dependent on this var as not replaceable. |
bdf50f60 | 523 | finished_with_expr can modify the bitmap, so we can't execute over it. */ |
524 | while (tab->kill_list[partition]) | |
525 | { | |
526 | version = bitmap_first_set_bit (tab->kill_list[partition]); | |
527 | finished_with_expr (tab, version, true); | |
528 | } | |
529 | ||
1b4345f7 | 530 | gcc_checking_assert (!tab->kill_list[partition]); |
bdf50f60 | 531 | } |
532 | ||
533 | ||
48e1416a | 534 | /* This function kills all expressions in TAB which are dependent on virtual |
bdf50f60 | 535 | partitions. */ |
536 | ||
537 | static inline void | |
538 | kill_virtual_exprs (temp_expr_table_p tab) | |
539 | { | |
540 | kill_expr (tab, VIRTUAL_PARTITION (tab)); | |
541 | } | |
542 | ||
543 | ||
544 | /* Mark the expression associated with VAR as replaceable, and enter | |
f0b5f617 | 545 | the defining stmt into the partition_dependencies table TAB. If |
bdf50f60 | 546 | MORE_REPLACING is true, accumulate the pending partition dependencies. */ |
547 | ||
548 | static void | |
549 | mark_replaceable (temp_expr_table_p tab, tree var, bool more_replacing) | |
550 | { | |
551 | int version = SSA_NAME_VERSION (var); | |
552 | ||
553 | /* Move the dependence list to the pending listpending. */ | |
554 | if (more_replacing && tab->partition_dependencies[version]) | |
48e1416a | 555 | bitmap_ior_into (tab->new_replaceable_dependencies, |
bdf50f60 | 556 | tab->partition_dependencies[version]); |
557 | ||
558 | finished_with_expr (tab, version, !more_replacing); | |
559 | ||
4fb07d00 | 560 | /* Set the replaceable expression. |
561 | The bitmap for this "escapes" from this file so it's allocated | |
562 | on the default obstack. */ | |
bdf50f60 | 563 | if (!tab->replaceable_expressions) |
dfdbf3fd | 564 | tab->replaceable_expressions = BITMAP_ALLOC (NULL); |
565 | bitmap_set_bit (tab->replaceable_expressions, version); | |
bdf50f60 | 566 | } |
567 | ||
568 | ||
5b26a9e3 | 569 | /* Helper function for find_ssaname_in_stores. Called via walk_tree to |
570 | find a SSA_NAME DATA somewhere in *TP. */ | |
571 | ||
572 | static tree | |
573 | find_ssaname (tree *tp, int *walk_subtrees, void *data) | |
574 | { | |
575 | tree var = (tree) data; | |
576 | if (*tp == var) | |
577 | return var; | |
578 | else if (IS_TYPE_OR_DECL_P (*tp)) | |
579 | *walk_subtrees = 0; | |
580 | return NULL_TREE; | |
581 | } | |
582 | ||
583 | /* Helper function for find_replaceable_in_bb. Return true if SSA_NAME DATA | |
584 | is used somewhere in T, which is a store in the statement. Called via | |
585 | walk_stmt_load_store_addr_ops. */ | |
586 | ||
587 | static bool | |
588 | find_ssaname_in_store (gimple, tree, tree t, void *data) | |
589 | { | |
590 | return walk_tree (&t, find_ssaname, data, NULL) != NULL_TREE; | |
591 | } | |
592 | ||
bdf50f60 | 593 | /* This function processes basic block BB, and looks for variables which can |
594 | be replaced by their expressions. Results are stored in the table TAB. */ | |
595 | ||
596 | static void | |
597 | find_replaceable_in_bb (temp_expr_table_p tab, basic_block bb) | |
598 | { | |
75a70cf9 | 599 | gimple_stmt_iterator bsi; |
600 | gimple stmt; | |
b029d3b7 | 601 | tree def, use, fndecl; |
bdf50f60 | 602 | int partition; |
603 | var_map map = tab->map; | |
604 | ssa_op_iter iter; | |
605 | bool stmt_replaceable; | |
b029d3b7 | 606 | int cur_call_cnt = 0; |
bdf50f60 | 607 | |
75a70cf9 | 608 | for (bsi = gsi_start_bb (bb); !gsi_end_p (bsi); gsi_next (&bsi)) |
bdf50f60 | 609 | { |
75a70cf9 | 610 | stmt = gsi_stmt (bsi); |
bdf50f60 | 611 | |
9845d120 | 612 | if (is_gimple_debug (stmt)) |
613 | continue; | |
614 | ||
f7373a91 | 615 | stmt_replaceable = ter_is_replaceable_p (stmt); |
75a70cf9 | 616 | |
bdf50f60 | 617 | /* Determine if this stmt finishes an existing expression. */ |
618 | FOR_EACH_SSA_TREE_OPERAND (use, stmt, iter, SSA_OP_USE) | |
619 | { | |
620 | unsigned ver = SSA_NAME_VERSION (use); | |
621 | ||
622 | /* If this use is a potential replacement variable, process it. */ | |
623 | if (tab->expr_decl_uids[ver]) | |
624 | { | |
625 | bool same_root_var = false; | |
626 | ssa_op_iter iter2; | |
627 | bitmap vars = tab->expr_decl_uids[ver]; | |
628 | ||
629 | /* See if the root variables are the same. If they are, we | |
630 | do not want to do the replacement to avoid problems with | |
631 | code size, see PR tree-optimization/17549. */ | |
632 | if (!bitmap_empty_p (vars)) | |
633 | FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter2, SSA_OP_DEF) | |
634 | { | |
ec11736b | 635 | if (SSA_NAME_VAR (def) |
636 | && bitmap_bit_p (vars, DECL_UID (SSA_NAME_VAR (def)))) | |
bdf50f60 | 637 | { |
638 | same_root_var = true; | |
639 | break; | |
640 | } | |
641 | } | |
642 | ||
182cf5a9 | 643 | /* If the stmt does a memory store and the replacement |
644 | is a load aliasing it avoid creating overlapping | |
645 | assignments which we cannot expand correctly. */ | |
c75add39 | 646 | if (gimple_vdef (stmt)) |
182cf5a9 | 647 | { |
648 | gimple def_stmt = SSA_NAME_DEF_STMT (use); | |
649 | while (is_gimple_assign (def_stmt) | |
650 | && gimple_assign_rhs_code (def_stmt) == SSA_NAME) | |
651 | def_stmt | |
652 | = SSA_NAME_DEF_STMT (gimple_assign_rhs1 (def_stmt)); | |
653 | if (gimple_vuse (def_stmt) | |
654 | && gimple_assign_single_p (def_stmt) | |
c75add39 | 655 | && stmt_may_clobber_ref_p (stmt, |
656 | gimple_assign_rhs1 (def_stmt))) | |
5b26a9e3 | 657 | { |
658 | /* For calls, it is not a problem if USE is among | |
659 | call's arguments or say OBJ_TYPE_REF argument, | |
660 | all those necessarily need to be evaluated before | |
661 | the call that may clobber the memory. But if | |
662 | LHS of the call refers to USE, expansion might | |
663 | evaluate it after the call, prevent TER in that | |
664 | case. | |
665 | For inline asm, allow TER of loads into input | |
666 | arguments, but disallow TER for USEs that occur | |
667 | somewhere in outputs. */ | |
668 | if (is_gimple_call (stmt) | |
669 | || gimple_code (stmt) == GIMPLE_ASM) | |
670 | { | |
671 | if (walk_stmt_load_store_ops (stmt, use, NULL, | |
672 | find_ssaname_in_store)) | |
673 | same_root_var = true; | |
674 | } | |
675 | else | |
676 | same_root_var = true; | |
677 | } | |
182cf5a9 | 678 | } |
679 | ||
b029d3b7 | 680 | /* Mark expression as replaceable unless stmt is volatile, or the |
48e1416a | 681 | def variable has the same root variable as something in the |
b029d3b7 | 682 | substitution list, or the def and use span a call such that |
683 | we'll expand lifetimes across a call. */ | |
9f80d051 | 684 | if (gimple_has_volatile_ops (stmt) || same_root_var |
685 | || (tab->call_cnt[ver] != cur_call_cnt | |
686 | && SINGLE_SSA_USE_OPERAND (SSA_NAME_DEF_STMT (use), SSA_OP_USE) | |
687 | == NULL_USE_OPERAND_P)) | |
bdf50f60 | 688 | finished_with_expr (tab, ver, true); |
689 | else | |
690 | mark_replaceable (tab, use, stmt_replaceable); | |
691 | } | |
692 | } | |
48e1416a | 693 | |
bdf50f60 | 694 | /* Next, see if this stmt kills off an active expression. */ |
695 | FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF) | |
696 | { | |
697 | partition = var_to_partition (map, def); | |
698 | if (partition != NO_PARTITION && tab->kill_list[partition]) | |
699 | kill_expr (tab, partition); | |
700 | } | |
701 | ||
b029d3b7 | 702 | /* Increment counter if this is a non BUILT_IN call. We allow |
703 | replacement over BUILT_IN calls since many will expand to inline | |
704 | insns instead of a true call. */ | |
705 | if (is_gimple_call (stmt) | |
706 | && !((fndecl = gimple_call_fndecl (stmt)) | |
707 | && DECL_BUILT_IN (fndecl))) | |
708 | cur_call_cnt++; | |
709 | ||
bdf50f60 | 710 | /* Now see if we are creating a new expression or not. */ |
711 | if (stmt_replaceable) | |
b029d3b7 | 712 | process_replaceable (tab, stmt, cur_call_cnt); |
bdf50f60 | 713 | |
714 | /* Free any unused dependency lists. */ | |
715 | bitmap_clear (tab->new_replaceable_dependencies); | |
716 | ||
717 | /* A V_{MAY,MUST}_DEF kills any expression using a virtual operand, | |
718 | including the current stmt. */ | |
dd277d48 | 719 | if (gimple_vdef (stmt)) |
bdf50f60 | 720 | kill_virtual_exprs (tab); |
721 | } | |
722 | } | |
723 | ||
724 | ||
725 | /* This function is the driver routine for replacement of temporary expressions | |
48e1416a | 726 | in the SSA->normal phase, operating on MAP. If there are replaceable |
727 | expressions, a table is returned which maps SSA versions to the | |
728 | expressions they should be replaced with. A NULL_TREE indicates no | |
729 | replacement should take place. If there are no replacements at all, | |
bdf50f60 | 730 | NULL is returned by the function, otherwise an expression vector indexed |
731 | by SSA_NAME version numbers. */ | |
732 | ||
4fb07d00 | 733 | bitmap |
bdf50f60 | 734 | find_replaceable_exprs (var_map map) |
735 | { | |
736 | basic_block bb; | |
737 | temp_expr_table_p table; | |
dfdbf3fd | 738 | bitmap ret; |
bdf50f60 | 739 | |
4fb07d00 | 740 | bitmap_obstack_initialize (&ter_bitmap_obstack); |
bdf50f60 | 741 | table = new_temp_expr_table (map); |
fc00614f | 742 | FOR_EACH_BB_FN (bb, cfun) |
bdf50f60 | 743 | { |
744 | find_replaceable_in_bb (table, bb); | |
1b4345f7 | 745 | gcc_checking_assert (bitmap_empty_p (table->partition_in_use)); |
bdf50f60 | 746 | } |
bdf50f60 | 747 | ret = free_temp_expr_table (table); |
4fb07d00 | 748 | bitmap_obstack_release (&ter_bitmap_obstack); |
bdf50f60 | 749 | return ret; |
48e1416a | 750 | } |
bdf50f60 | 751 | |
752 | /* Dump TER expression table EXPR to file F. */ | |
753 | ||
75a70cf9 | 754 | void |
dfdbf3fd | 755 | dump_replaceable_exprs (FILE *f, bitmap expr) |
bdf50f60 | 756 | { |
75a70cf9 | 757 | tree var; |
758 | unsigned x; | |
bdf50f60 | 759 | |
760 | fprintf (f, "\nReplacing Expressions\n"); | |
75a70cf9 | 761 | for (x = 0; x < num_ssa_names; x++) |
dfdbf3fd | 762 | if (bitmap_bit_p (expr, x)) |
bdf50f60 | 763 | { |
75a70cf9 | 764 | var = ssa_name (x); |
bdf50f60 | 765 | print_generic_expr (f, var, TDF_SLIM); |
766 | fprintf (f, " replace with --> "); | |
dfdbf3fd | 767 | print_gimple_stmt (f, SSA_NAME_DEF_STMT (var), 0, TDF_SLIM); |
bdf50f60 | 768 | fprintf (f, "\n"); |
769 | } | |
770 | fprintf (f, "\n"); | |
771 | } | |
772 | ||
773 | ||
774 | #ifdef ENABLE_CHECKING | |
775 | /* Dump the status of the various tables in the expression table. This is used | |
776 | exclusively to debug TER. F is the place to send debug info and T is the | |
777 | table being debugged. */ | |
778 | ||
4b987fac | 779 | DEBUG_FUNCTION void |
bdf50f60 | 780 | debug_ter (FILE *f, temp_expr_table_p t) |
781 | { | |
782 | unsigned x, y; | |
783 | bitmap_iterator bi; | |
784 | ||
48e1416a | 785 | fprintf (f, "\nDumping current state of TER\n virtual partition = %d\n", |
bdf50f60 | 786 | VIRTUAL_PARTITION (t)); |
787 | if (t->replaceable_expressions) | |
788 | dump_replaceable_exprs (f, t->replaceable_expressions); | |
789 | fprintf (f, "Currently tracking the following expressions:\n"); | |
790 | ||
791 | for (x = 1; x < num_ssa_names; x++) | |
792 | if (t->expr_decl_uids[x]) | |
793 | { | |
b029d3b7 | 794 | print_generic_expr (f, ssa_name (x), TDF_SLIM); |
bdf50f60 | 795 | fprintf (f, " dep-parts : "); |
48e1416a | 796 | if (t->partition_dependencies[x] |
bdf50f60 | 797 | && !bitmap_empty_p (t->partition_dependencies[x])) |
798 | { | |
799 | EXECUTE_IF_SET_IN_BITMAP (t->partition_dependencies[x], 0, y, bi) | |
800 | fprintf (f, "P%d ",y); | |
801 | } | |
b029d3b7 | 802 | fprintf (f, " basedecls: "); |
bdf50f60 | 803 | EXECUTE_IF_SET_IN_BITMAP (t->expr_decl_uids[x], 0, y, bi) |
804 | fprintf (f, "%d ",y); | |
b029d3b7 | 805 | fprintf (f, " call_cnt : %d",t->call_cnt[x]); |
806 | fprintf (f, "\n"); | |
bdf50f60 | 807 | } |
808 | ||
48e1416a | 809 | bitmap_print (f, t->partition_in_use, "Partitions in use ", |
bdf50f60 | 810 | "\npartition KILL lists:\n"); |
811 | ||
812 | for (x = 0; x <= num_var_partitions (t->map); x++) | |
813 | if (t->kill_list[x]) | |
814 | { | |
815 | fprintf (f, "Partition %d : ", x); | |
816 | EXECUTE_IF_SET_IN_BITMAP (t->kill_list[x], 0, y, bi) | |
817 | fprintf (f, "_%d ",y); | |
818 | } | |
819 | ||
820 | fprintf (f, "\n----------\n"); | |
821 | } | |
822 | #endif |