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bdf50f60 | 1 | /* Routines for performing Temporary Expression Replacement (TER) in SSA trees. |
71e45bc2 | 2 | Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012 |
ce084dfc | 3 | Free Software Foundation, Inc. |
bdf50f60 | 4 | Contributed by Andrew MacLeod <amacleod@redhat.com> |
5 | ||
6 | This file is part of GCC. | |
7 | ||
8 | GCC is free software; you can redistribute it and/or modify | |
9 | it under the terms of the GNU General Public License as published by | |
8c4c00c1 | 10 | the Free Software Foundation; either version 3, or (at your option) |
bdf50f60 | 11 | any later version. |
12 | ||
13 | GCC is distributed in the hope that it will be useful, | |
14 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
16 | GNU General Public License for more details. | |
17 | ||
18 | You should have received a copy of the GNU General Public License | |
8c4c00c1 | 19 | along with GCC; see the file COPYING3. If not see |
20 | <http://www.gnu.org/licenses/>. */ | |
bdf50f60 | 21 | |
22 | ||
23 | #include "config.h" | |
24 | #include "system.h" | |
25 | #include "coretypes.h" | |
26 | #include "tm.h" | |
27 | #include "tree.h" | |
ce084dfc | 28 | #include "gimple-pretty-print.h" |
bdf50f60 | 29 | #include "bitmap.h" |
30 | #include "tree-flow.h" | |
b9ed1410 | 31 | #include "dumpfile.h" |
bdf50f60 | 32 | #include "tree-ssa-live.h" |
bff4202c | 33 | #include "flags.h" |
bdf50f60 | 34 | |
35 | ||
36 | /* Temporary Expression Replacement (TER) | |
37 | ||
38 | Replace SSA version variables during out-of-ssa with their defining | |
48e1416a | 39 | expression if there is only one use of the variable. |
bdf50f60 | 40 | |
41 | This pass is required in order for the RTL expansion pass to see larger | |
42 | chunks of code. This allows it to make better choices on RTL pattern | |
43 | selection. When expand is rewritten and merged with out-of-ssa, and | |
48e1416a | 44 | understands SSA, this should be eliminated. |
bdf50f60 | 45 | |
46 | A pass is made through the function, one block at a time. No cross block | |
47 | information is tracked. | |
48 | ||
49 | Variables which only have one use, and whose defining stmt is considered | |
50 | a replaceable expression (see is_replaceable_p) are tracked to see whether | |
48e1416a | 51 | they can be replaced at their use location. |
52 | ||
bdf50f60 | 53 | n_12 = C * 10 |
54 | a_2 = b_5 + 6 | |
55 | v_9 = a_2 * n_12 | |
56 | ||
57 | if there are the only use of n_12 and a_2, TER will substitute in their | |
58 | expressions in v_9, and end up with: | |
59 | ||
60 | v_9 = (b_5 + 6) * (C * 10) | |
61 | ||
62 | which will then have the ssa_name assigned to regular variables, and the | |
f0b5f617 | 63 | resulting code which will be passed to the expander looks something like: |
bdf50f60 | 64 | |
65 | v = (b + 6) * (C * 10) | |
66 | ||
48e1416a | 67 | |
68 | This requires ensuring that none of the variables used by the expression | |
69 | change between the def point and where it is used. Furthermore, if any | |
70 | of the ssa_names used in this expression are themselves replaceable, we | |
71 | have to ensure none of that expressions' arguments change either. | |
72 | Although SSA_NAMES themselves don't change, this pass is performed after | |
73 | coalescing has coalesced different SSA_NAMES together, so there could be a | |
bdf50f60 | 74 | definition of an SSA_NAME which is coalesced with a use that causes a |
f0b5f617 | 75 | problem, i.e., |
48e1416a | 76 | |
bdf50f60 | 77 | PHI b_5 = <b_8(2), b_14(1)> |
78 | <...> | |
79 | a_2 = b_5 + 6 | |
80 | b_8 = c_4 + 4 | |
81 | v_9 = a_2 * n_12 | |
82 | <...> | |
83 | ||
7920eed5 | 84 | If b_5, b_8 and b_14 are all coalesced together... |
bdf50f60 | 85 | The expression b_5 + 6 CANNOT replace the use in the statement defining v_9 |
86 | because b_8 is in fact killing the value of b_5 since they share a partition | |
7920eed5 | 87 | and will be assigned the same memory or register location. |
48e1416a | 88 | |
bdf50f60 | 89 | TER implements this but stepping through the instructions in a block and |
7920eed5 | 90 | tracking potential expressions for replacement, and the partitions they are |
bdf50f60 | 91 | dependent on. Expressions are represented by the SSA_NAME_VERSION of the |
75a70cf9 | 92 | DEF on the LHS of a GIMPLE_ASSIGN and the expression is the RHS. |
bdf50f60 | 93 | |
94 | When a stmt is determined to be a possible replacement expression, the | |
95 | following steps are taken: | |
96 | ||
48e1416a | 97 | EXPR_DECL_UID bitmap is allocated and set to the base variable UID of the |
98 | def and any uses in the expression. non-NULL means the expression is being | |
bdf50f60 | 99 | tracked. The UID's themselves are used to prevent TER substitution into |
f0b5f617 | 100 | accumulating sequences, i.e., |
101 | ||
bdf50f60 | 102 | x = x + y |
103 | x = x + z | |
104 | x = x + w | |
105 | etc. | |
106 | this can result in very large expressions which don't accomplish anything | |
48e1416a | 107 | see PR tree-optimization/17549. |
bdf50f60 | 108 | |
48e1416a | 109 | PARTITION_DEPENDENCIES is another bitmap array, and it has a bit set for any |
bdf50f60 | 110 | partition which is used in the expression. This is primarily used to remove |
111 | an expression from the partition kill lists when a decision is made whether | |
112 | to replace it or not. This is indexed by ssa version number as well, and | |
113 | indicates a partition number. virtual operands are not tracked individually, | |
7920eed5 | 114 | but they are summarized by an artificial partition called VIRTUAL_PARTITION. |
115 | This means a MAY or MUST def will kill *ALL* expressions that are dependent | |
bdf50f60 | 116 | on a virtual operand. |
48e1416a | 117 | Note that the EXPR_DECL_UID and this bitmap represent very similar |
bdf50f60 | 118 | information, but the info in one is not easy to obtain from the other. |
119 | ||
120 | KILL_LIST is yet another bitmap array, this time it is indexed by partition | |
48e1416a | 121 | number, and represents a list of active expressions which will will no |
bdf50f60 | 122 | longer be valid if a definition into this partition takes place. |
123 | ||
124 | PARTITION_IN_USE is simply a bitmap which is used to track which partitions | |
48e1416a | 125 | currently have something in their kill list. This is used at the end of |
bdf50f60 | 126 | a block to clear out the KILL_LIST bitmaps at the end of each block. |
127 | ||
48e1416a | 128 | NEW_REPLACEABLE_DEPENDENCIES is used as a temporary place to store |
f0b5f617 | 129 | dependencies which will be reused by the current definition. All the uses |
bdf50f60 | 130 | on an expression are processed before anything else is done. If a use is |
131 | determined to be a replaceable expression AND the current stmt is also going | |
132 | to be replaceable, all the dependencies of this replaceable use will be | |
133 | picked up by the current stmt's expression. Rather than recreate them, they | |
134 | are simply copied here and then copied into the new expression when it is | |
135 | processed. | |
136 | ||
137 | a_2 = b_5 + 6 | |
138 | v_8 = a_2 + c_4 | |
139 | ||
48e1416a | 140 | a_2's expression 'b_5 + 6' is determined to be replaceable at the use |
bdf50f60 | 141 | location. It is dependent on the partition 'b_5' is in. This is cached into |
f0b5f617 | 142 | the NEW_REPLACEABLE_DEPENDENCIES bitmap, and when v_8 is examined for |
143 | replaceability, it is a candidate, and it is dependent on the partition | |
bdf50f60 | 144 | b_5 is in *NOT* a_2, as well as c_4's partition. |
145 | ||
146 | if v_8 is also replaceable: | |
147 | ||
148 | x_9 = v_8 * 5 | |
149 | ||
150 | x_9 is dependent on partitions b_5, and c_4 | |
48e1416a | 151 | |
152 | if a statement is found which has either of those partitions written to | |
bdf50f60 | 153 | before x_9 is used, then x_9 itself is NOT replaceable. */ |
154 | ||
155 | ||
156 | /* Temporary Expression Replacement (TER) table information. */ | |
157 | ||
48e1416a | 158 | typedef struct temp_expr_table_d |
bdf50f60 | 159 | { |
160 | var_map map; | |
161 | bitmap *partition_dependencies; /* Partitions expr is dependent on. */ | |
dfdbf3fd | 162 | bitmap replaceable_expressions; /* Replacement expression table. */ |
bdf50f60 | 163 | bitmap *expr_decl_uids; /* Base uids of exprs. */ |
164 | bitmap *kill_list; /* Expr's killed by a partition. */ | |
7920eed5 | 165 | int virtual_partition; /* Pseudo partition for virtual ops. */ |
166 | bitmap partition_in_use; /* Partitions with kill entries. */ | |
bdf50f60 | 167 | bitmap new_replaceable_dependencies; /* Holding place for pending dep's. */ |
168 | int *num_in_part; /* # of ssa_names in a partition. */ | |
b029d3b7 | 169 | int *call_cnt; /* Call count at definition. */ |
bdf50f60 | 170 | } *temp_expr_table_p; |
171 | ||
4fb5e5ca | 172 | /* Used to indicate a dependency on VDEFs. */ |
bdf50f60 | 173 | #define VIRTUAL_PARTITION(table) (table->virtual_partition) |
174 | ||
4fb07d00 | 175 | /* A place for the many, many bitmaps we create. */ |
176 | static bitmap_obstack ter_bitmap_obstack; | |
177 | ||
bdf50f60 | 178 | #ifdef ENABLE_CHECKING |
179 | extern void debug_ter (FILE *, temp_expr_table_p); | |
180 | #endif | |
181 | ||
182 | ||
183 | /* Create a new TER table for MAP. */ | |
184 | ||
185 | static temp_expr_table_p | |
186 | new_temp_expr_table (var_map map) | |
187 | { | |
188 | temp_expr_table_p t; | |
189 | unsigned x; | |
190 | ||
191 | t = XNEW (struct temp_expr_table_d); | |
192 | t->map = map; | |
193 | ||
194 | t->partition_dependencies = XCNEWVEC (bitmap, num_ssa_names + 1); | |
195 | t->expr_decl_uids = XCNEWVEC (bitmap, num_ssa_names + 1); | |
196 | t->kill_list = XCNEWVEC (bitmap, num_var_partitions (map) + 1); | |
197 | ||
4fb07d00 | 198 | t->partition_in_use = BITMAP_ALLOC (&ter_bitmap_obstack); |
bdf50f60 | 199 | |
200 | t->virtual_partition = num_var_partitions (map); | |
4fb07d00 | 201 | t->new_replaceable_dependencies = BITMAP_ALLOC (&ter_bitmap_obstack); |
bdf50f60 | 202 | |
203 | t->replaceable_expressions = NULL; | |
204 | t->num_in_part = XCNEWVEC (int, num_var_partitions (map)); | |
205 | for (x = 1; x < num_ssa_names; x++) | |
206 | { | |
207 | int p; | |
208 | tree name = ssa_name (x); | |
209 | if (!name) | |
210 | continue; | |
211 | p = var_to_partition (map, name); | |
212 | if (p != NO_PARTITION) | |
213 | t->num_in_part[p]++; | |
214 | } | |
b029d3b7 | 215 | t->call_cnt = XCNEWVEC (int, num_ssa_names + 1); |
bdf50f60 | 216 | |
217 | return t; | |
218 | } | |
219 | ||
220 | ||
48e1416a | 221 | /* Free TER table T. If there are valid replacements, return the expression |
bdf50f60 | 222 | vector. */ |
223 | ||
dfdbf3fd | 224 | static bitmap |
bdf50f60 | 225 | free_temp_expr_table (temp_expr_table_p t) |
226 | { | |
dfdbf3fd | 227 | bitmap ret = NULL; |
bdf50f60 | 228 | |
229 | #ifdef ENABLE_CHECKING | |
230 | unsigned x; | |
231 | for (x = 0; x <= num_var_partitions (t->map); x++) | |
232 | gcc_assert (!t->kill_list[x]); | |
0d3f8fd5 | 233 | for (x = 0; x < num_ssa_names; x++) |
464cc29a | 234 | { |
235 | gcc_assert (t->expr_decl_uids[x] == NULL); | |
236 | gcc_assert (t->partition_dependencies[x] == NULL); | |
237 | } | |
bdf50f60 | 238 | #endif |
239 | ||
240 | BITMAP_FREE (t->partition_in_use); | |
c2df357d | 241 | BITMAP_FREE (t->new_replaceable_dependencies); |
bdf50f60 | 242 | |
bdf50f60 | 243 | free (t->expr_decl_uids); |
bdf50f60 | 244 | free (t->kill_list); |
245 | free (t->partition_dependencies); | |
c2df357d | 246 | free (t->num_in_part); |
b029d3b7 | 247 | free (t->call_cnt); |
bdf50f60 | 248 | |
249 | if (t->replaceable_expressions) | |
250 | ret = t->replaceable_expressions; | |
251 | ||
252 | free (t); | |
253 | return ret; | |
254 | } | |
255 | ||
256 | ||
257 | /* Return TRUE if VERSION is to be replaced by an expression in TAB. */ | |
258 | ||
259 | static inline bool | |
260 | version_to_be_replaced_p (temp_expr_table_p tab, int version) | |
261 | { | |
262 | if (!tab->replaceable_expressions) | |
263 | return false; | |
dfdbf3fd | 264 | return bitmap_bit_p (tab->replaceable_expressions, version); |
bdf50f60 | 265 | } |
266 | ||
267 | ||
48e1416a | 268 | /* Add partition P to the list if partitions VERSION is dependent on. TAB is |
bdf50f60 | 269 | the expression table */ |
270 | ||
271 | static inline void | |
272 | make_dependent_on_partition (temp_expr_table_p tab, int version, int p) | |
273 | { | |
274 | if (!tab->partition_dependencies[version]) | |
4fb07d00 | 275 | tab->partition_dependencies[version] = BITMAP_ALLOC (&ter_bitmap_obstack); |
bdf50f60 | 276 | |
277 | bitmap_set_bit (tab->partition_dependencies[version], p); | |
278 | } | |
279 | ||
280 | ||
281 | /* Add VER to the kill list for P. TAB is the expression table */ | |
282 | ||
283 | static inline void | |
284 | add_to_partition_kill_list (temp_expr_table_p tab, int p, int ver) | |
285 | { | |
286 | if (!tab->kill_list[p]) | |
287 | { | |
4fb07d00 | 288 | tab->kill_list[p] = BITMAP_ALLOC (&ter_bitmap_obstack); |
bdf50f60 | 289 | bitmap_set_bit (tab->partition_in_use, p); |
290 | } | |
291 | bitmap_set_bit (tab->kill_list[p], ver); | |
292 | } | |
293 | ||
294 | ||
48e1416a | 295 | /* Remove VER from the partition kill list for P. TAB is the expression |
bdf50f60 | 296 | table. */ |
297 | ||
48e1416a | 298 | static inline void |
bdf50f60 | 299 | remove_from_partition_kill_list (temp_expr_table_p tab, int p, int version) |
300 | { | |
1b4345f7 | 301 | gcc_checking_assert (tab->kill_list[p]); |
bdf50f60 | 302 | bitmap_clear_bit (tab->kill_list[p], version); |
303 | if (bitmap_empty_p (tab->kill_list[p])) | |
304 | { | |
305 | bitmap_clear_bit (tab->partition_in_use, p); | |
306 | BITMAP_FREE (tab->kill_list[p]); | |
307 | } | |
308 | } | |
309 | ||
310 | ||
48e1416a | 311 | /* Add a dependency between the def of ssa VERSION and VAR. If VAR is |
312 | replaceable by an expression, add a dependence each of the elements of the | |
bdf50f60 | 313 | expression. These are contained in the new_replaceable list. TAB is the |
314 | expression table. */ | |
315 | ||
316 | static void | |
317 | add_dependence (temp_expr_table_p tab, int version, tree var) | |
318 | { | |
319 | int i; | |
320 | bitmap_iterator bi; | |
321 | unsigned x; | |
322 | ||
323 | i = SSA_NAME_VERSION (var); | |
324 | if (version_to_be_replaced_p (tab, i)) | |
325 | { | |
326 | if (!bitmap_empty_p (tab->new_replaceable_dependencies)) | |
327 | { | |
48e1416a | 328 | /* Version will now be killed by a write to any partition the |
bdf50f60 | 329 | substituted expression would have been killed by. */ |
330 | EXECUTE_IF_SET_IN_BITMAP (tab->new_replaceable_dependencies, 0, x, bi) | |
331 | add_to_partition_kill_list (tab, x, version); | |
332 | ||
48e1416a | 333 | /* Rather than set partition_dependencies and in_use lists bit by |
bdf50f60 | 334 | bit, simply OR in the new_replaceable_dependencies bits. */ |
335 | if (!tab->partition_dependencies[version]) | |
4fb07d00 | 336 | tab->partition_dependencies[version] = |
337 | BITMAP_ALLOC (&ter_bitmap_obstack); | |
48e1416a | 338 | bitmap_ior_into (tab->partition_dependencies[version], |
bdf50f60 | 339 | tab->new_replaceable_dependencies); |
48e1416a | 340 | bitmap_ior_into (tab->partition_in_use, |
bdf50f60 | 341 | tab->new_replaceable_dependencies); |
342 | /* It is only necessary to add these once. */ | |
343 | bitmap_clear (tab->new_replaceable_dependencies); | |
344 | } | |
345 | } | |
346 | else | |
347 | { | |
348 | i = var_to_partition (tab->map, var); | |
1b4345f7 | 349 | gcc_checking_assert (i != NO_PARTITION); |
350 | gcc_checking_assert (tab->num_in_part[i] != 0); | |
bdf50f60 | 351 | /* Only dependencies on ssa_names which are coalesced with something need |
352 | to be tracked. Partitions with containing only a single SSA_NAME | |
353 | *cannot* have their value changed. */ | |
354 | if (tab->num_in_part[i] > 1) | |
355 | { | |
356 | add_to_partition_kill_list (tab, i, version); | |
357 | make_dependent_on_partition (tab, version, i); | |
358 | } | |
359 | } | |
360 | } | |
361 | ||
362 | ||
351b6ccf | 363 | /* Return TRUE if expression STMT is suitable for replacement. |
364 | TER is true if is_replaceable_p is called from within TER, false | |
365 | when used from within stmt_is_replaceable_p, i.e. EXPAND_INITIALIZER | |
366 | expansion. The differences are that with !TER some tests are skipped | |
367 | to make it more aggressive (doesn't require the same bb, or for -O0 | |
368 | same locus and same BLOCK), on the other side never considers memory | |
369 | loads as replaceable, because those don't ever lead into constant | |
370 | expressions. */ | |
bdf50f60 | 371 | |
372 | static inline bool | |
351b6ccf | 373 | is_replaceable_p (gimple stmt, bool ter) |
bdf50f60 | 374 | { |
bdf50f60 | 375 | use_operand_p use_p; |
75a70cf9 | 376 | tree def; |
377 | gimple use_stmt; | |
bff4202c | 378 | location_t locus1, locus2; |
379 | tree block1, block2; | |
bdf50f60 | 380 | |
381 | /* Only consider modify stmts. */ | |
75a70cf9 | 382 | if (!is_gimple_assign (stmt)) |
bdf50f60 | 383 | return false; |
384 | ||
52dfd149 | 385 | /* If the statement may throw an exception, it cannot be replaced. */ |
75a70cf9 | 386 | if (stmt_could_throw_p (stmt)) |
52dfd149 | 387 | return false; |
388 | ||
bdf50f60 | 389 | /* Punt if there is more than 1 def. */ |
390 | def = SINGLE_SSA_TREE_OPERAND (stmt, SSA_OP_DEF); | |
391 | if (!def) | |
392 | return false; | |
393 | ||
394 | /* Only consider definitions which have a single use. */ | |
395 | if (!single_imm_use (def, &use_p, &use_stmt)) | |
396 | return false; | |
397 | ||
398 | /* If the use isn't in this block, it wont be replaced either. */ | |
351b6ccf | 399 | if (ter && gimple_bb (use_stmt) != gimple_bb (stmt)) |
bdf50f60 | 400 | return false; |
401 | ||
75a70cf9 | 402 | locus1 = gimple_location (stmt); |
403 | block1 = gimple_block (stmt); | |
404 | ||
405 | if (gimple_code (use_stmt) == GIMPLE_PHI) | |
bff4202c | 406 | { |
407 | locus2 = 0; | |
408 | block2 = NULL_TREE; | |
409 | } | |
410 | else | |
411 | { | |
75a70cf9 | 412 | locus2 = gimple_location (use_stmt); |
413 | block2 = gimple_block (use_stmt); | |
bff4202c | 414 | } |
415 | ||
416 | if (!optimize | |
351b6ccf | 417 | && ter |
bff4202c | 418 | && ((locus1 && locus1 != locus2) || (block1 && block1 != block2))) |
419 | return false; | |
420 | ||
bdf50f60 | 421 | /* Used in this block, but at the TOP of the block, not the end. */ |
75a70cf9 | 422 | if (gimple_code (use_stmt) == GIMPLE_PHI) |
bdf50f60 | 423 | return false; |
424 | ||
4fb5e5ca | 425 | /* There must be no VDEFs. */ |
dd277d48 | 426 | if (gimple_vdef (stmt)) |
bdf50f60 | 427 | return false; |
428 | ||
bff4202c | 429 | /* Without alias info we can't move around loads. */ |
351b6ccf | 430 | if ((!optimize || !ter) |
7d9a35b8 | 431 | && gimple_assign_single_p (stmt) |
432 | && !is_gimple_val (gimple_assign_rhs1 (stmt))) | |
bff4202c | 433 | return false; |
434 | ||
bdf50f60 | 435 | /* Float expressions must go through memory if float-store is on. */ |
48e1416a | 436 | if (flag_float_store |
75a70cf9 | 437 | && FLOAT_TYPE_P (gimple_expr_type (stmt))) |
bdf50f60 | 438 | return false; |
439 | ||
dac21d57 | 440 | /* An assignment with a register variable on the RHS is not |
441 | replaceable. */ | |
75a70cf9 | 442 | if (gimple_assign_rhs_code (stmt) == VAR_DECL |
443 | && DECL_HARD_REGISTER (gimple_assign_rhs1 (stmt))) | |
dac21d57 | 444 | return false; |
445 | ||
abfb4f34 | 446 | /* No function calls can be replaced. */ |
75a70cf9 | 447 | if (is_gimple_call (stmt)) |
abfb4f34 | 448 | return false; |
bdf50f60 | 449 | |
d819917f | 450 | /* Leave any stmt with volatile operands alone as well. */ |
75a70cf9 | 451 | if (gimple_has_volatile_ops (stmt)) |
bdf50f60 | 452 | return false; |
bdf50f60 | 453 | |
454 | return true; | |
455 | } | |
456 | ||
457 | ||
351b6ccf | 458 | /* Variant of is_replaceable_p test for use in EXPAND_INITIALIZER |
459 | expansion. */ | |
460 | ||
461 | bool | |
462 | stmt_is_replaceable_p (gimple stmt) | |
463 | { | |
464 | return is_replaceable_p (stmt, false); | |
465 | } | |
466 | ||
467 | ||
48e1416a | 468 | /* This function will remove the expression for VERSION from replacement |
469 | consideration in table TAB. If FREE_EXPR is true, then remove the | |
bdf50f60 | 470 | expression from consideration as well by freeing the decl uid bitmap. */ |
471 | ||
472 | static void | |
473 | finished_with_expr (temp_expr_table_p tab, int version, bool free_expr) | |
474 | { | |
475 | unsigned i; | |
476 | bitmap_iterator bi; | |
477 | ||
478 | /* Remove this expression from its dependent lists. The partition dependence | |
9d75589a | 479 | list is retained and transferred later to whomever uses this version. */ |
bdf50f60 | 480 | if (tab->partition_dependencies[version]) |
481 | { | |
482 | EXECUTE_IF_SET_IN_BITMAP (tab->partition_dependencies[version], 0, i, bi) | |
483 | remove_from_partition_kill_list (tab, i, version); | |
484 | BITMAP_FREE (tab->partition_dependencies[version]); | |
485 | } | |
486 | if (free_expr) | |
487 | BITMAP_FREE (tab->expr_decl_uids[version]); | |
488 | } | |
489 | ||
490 | ||
0b7780cd | 491 | /* Create an expression entry for a replaceable expression. */ |
bdf50f60 | 492 | |
48e1416a | 493 | static void |
b029d3b7 | 494 | process_replaceable (temp_expr_table_p tab, gimple stmt, int call_cnt) |
bdf50f60 | 495 | { |
496 | tree var, def, basevar; | |
497 | int version; | |
498 | ssa_op_iter iter; | |
499 | bitmap def_vars, use_vars; | |
500 | ||
351b6ccf | 501 | gcc_checking_assert (is_replaceable_p (stmt, true)); |
bdf50f60 | 502 | |
503 | def = SINGLE_SSA_TREE_OPERAND (stmt, SSA_OP_DEF); | |
504 | version = SSA_NAME_VERSION (def); | |
4fb07d00 | 505 | def_vars = BITMAP_ALLOC (&ter_bitmap_obstack); |
bdf50f60 | 506 | |
ec11736b | 507 | basevar = SSA_NAME_VAR (def); |
508 | if (basevar) | |
509 | bitmap_set_bit (def_vars, DECL_UID (basevar)); | |
bdf50f60 | 510 | |
511 | /* Add this expression to the dependency list for each use partition. */ | |
512 | FOR_EACH_SSA_TREE_OPERAND (var, stmt, iter, SSA_OP_USE) | |
513 | { | |
514 | int var_version = SSA_NAME_VERSION (var); | |
515 | ||
516 | use_vars = tab->expr_decl_uids[var_version]; | |
517 | add_dependence (tab, version, var); | |
518 | if (use_vars) | |
519 | { | |
520 | bitmap_ior_into (def_vars, use_vars); | |
521 | BITMAP_FREE (tab->expr_decl_uids[var_version]); | |
522 | } | |
ec11736b | 523 | else if (SSA_NAME_VAR (var)) |
bdf50f60 | 524 | bitmap_set_bit (def_vars, DECL_UID (SSA_NAME_VAR (var))); |
525 | } | |
526 | tab->expr_decl_uids[version] = def_vars; | |
527 | ||
528 | /* If there are VUSES, add a dependence on virtual defs. */ | |
dd277d48 | 529 | if (gimple_vuse (stmt)) |
bdf50f60 | 530 | { |
531 | make_dependent_on_partition (tab, version, VIRTUAL_PARTITION (tab)); | |
532 | add_to_partition_kill_list (tab, VIRTUAL_PARTITION (tab), version); | |
533 | } | |
b029d3b7 | 534 | |
535 | tab->call_cnt[version] = call_cnt; | |
bdf50f60 | 536 | } |
537 | ||
538 | ||
539 | /* This function removes any expression in TAB which is dependent on PARTITION | |
540 | from consideration, making it not replaceable. */ | |
541 | ||
542 | static inline void | |
543 | kill_expr (temp_expr_table_p tab, int partition) | |
544 | { | |
545 | unsigned version; | |
546 | ||
48e1416a | 547 | /* Mark every active expr dependent on this var as not replaceable. |
bdf50f60 | 548 | finished_with_expr can modify the bitmap, so we can't execute over it. */ |
549 | while (tab->kill_list[partition]) | |
550 | { | |
551 | version = bitmap_first_set_bit (tab->kill_list[partition]); | |
552 | finished_with_expr (tab, version, true); | |
553 | } | |
554 | ||
1b4345f7 | 555 | gcc_checking_assert (!tab->kill_list[partition]); |
bdf50f60 | 556 | } |
557 | ||
558 | ||
48e1416a | 559 | /* This function kills all expressions in TAB which are dependent on virtual |
bdf50f60 | 560 | partitions. */ |
561 | ||
562 | static inline void | |
563 | kill_virtual_exprs (temp_expr_table_p tab) | |
564 | { | |
565 | kill_expr (tab, VIRTUAL_PARTITION (tab)); | |
566 | } | |
567 | ||
568 | ||
569 | /* Mark the expression associated with VAR as replaceable, and enter | |
f0b5f617 | 570 | the defining stmt into the partition_dependencies table TAB. If |
bdf50f60 | 571 | MORE_REPLACING is true, accumulate the pending partition dependencies. */ |
572 | ||
573 | static void | |
574 | mark_replaceable (temp_expr_table_p tab, tree var, bool more_replacing) | |
575 | { | |
576 | int version = SSA_NAME_VERSION (var); | |
577 | ||
578 | /* Move the dependence list to the pending listpending. */ | |
579 | if (more_replacing && tab->partition_dependencies[version]) | |
48e1416a | 580 | bitmap_ior_into (tab->new_replaceable_dependencies, |
bdf50f60 | 581 | tab->partition_dependencies[version]); |
582 | ||
583 | finished_with_expr (tab, version, !more_replacing); | |
584 | ||
4fb07d00 | 585 | /* Set the replaceable expression. |
586 | The bitmap for this "escapes" from this file so it's allocated | |
587 | on the default obstack. */ | |
bdf50f60 | 588 | if (!tab->replaceable_expressions) |
dfdbf3fd | 589 | tab->replaceable_expressions = BITMAP_ALLOC (NULL); |
590 | bitmap_set_bit (tab->replaceable_expressions, version); | |
bdf50f60 | 591 | } |
592 | ||
593 | ||
594 | /* This function processes basic block BB, and looks for variables which can | |
595 | be replaced by their expressions. Results are stored in the table TAB. */ | |
596 | ||
597 | static void | |
598 | find_replaceable_in_bb (temp_expr_table_p tab, basic_block bb) | |
599 | { | |
75a70cf9 | 600 | gimple_stmt_iterator bsi; |
601 | gimple stmt; | |
b029d3b7 | 602 | tree def, use, fndecl; |
bdf50f60 | 603 | int partition; |
604 | var_map map = tab->map; | |
605 | ssa_op_iter iter; | |
606 | bool stmt_replaceable; | |
b029d3b7 | 607 | int cur_call_cnt = 0; |
bdf50f60 | 608 | |
75a70cf9 | 609 | for (bsi = gsi_start_bb (bb); !gsi_end_p (bsi); gsi_next (&bsi)) |
bdf50f60 | 610 | { |
75a70cf9 | 611 | stmt = gsi_stmt (bsi); |
bdf50f60 | 612 | |
9845d120 | 613 | if (is_gimple_debug (stmt)) |
614 | continue; | |
615 | ||
351b6ccf | 616 | stmt_replaceable = is_replaceable_p (stmt, true); |
75a70cf9 | 617 | |
bdf50f60 | 618 | /* Determine if this stmt finishes an existing expression. */ |
619 | FOR_EACH_SSA_TREE_OPERAND (use, stmt, iter, SSA_OP_USE) | |
620 | { | |
621 | unsigned ver = SSA_NAME_VERSION (use); | |
622 | ||
623 | /* If this use is a potential replacement variable, process it. */ | |
624 | if (tab->expr_decl_uids[ver]) | |
625 | { | |
626 | bool same_root_var = false; | |
627 | ssa_op_iter iter2; | |
628 | bitmap vars = tab->expr_decl_uids[ver]; | |
629 | ||
630 | /* See if the root variables are the same. If they are, we | |
631 | do not want to do the replacement to avoid problems with | |
632 | code size, see PR tree-optimization/17549. */ | |
633 | if (!bitmap_empty_p (vars)) | |
634 | FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter2, SSA_OP_DEF) | |
635 | { | |
ec11736b | 636 | if (SSA_NAME_VAR (def) |
637 | && bitmap_bit_p (vars, DECL_UID (SSA_NAME_VAR (def)))) | |
bdf50f60 | 638 | { |
639 | same_root_var = true; | |
640 | break; | |
641 | } | |
642 | } | |
643 | ||
182cf5a9 | 644 | /* If the stmt does a memory store and the replacement |
645 | is a load aliasing it avoid creating overlapping | |
646 | assignments which we cannot expand correctly. */ | |
647 | if (gimple_vdef (stmt) | |
648 | && gimple_assign_single_p (stmt)) | |
649 | { | |
650 | gimple def_stmt = SSA_NAME_DEF_STMT (use); | |
651 | while (is_gimple_assign (def_stmt) | |
652 | && gimple_assign_rhs_code (def_stmt) == SSA_NAME) | |
653 | def_stmt | |
654 | = SSA_NAME_DEF_STMT (gimple_assign_rhs1 (def_stmt)); | |
655 | if (gimple_vuse (def_stmt) | |
656 | && gimple_assign_single_p (def_stmt) | |
657 | && refs_may_alias_p (gimple_assign_lhs (stmt), | |
658 | gimple_assign_rhs1 (def_stmt))) | |
659 | same_root_var = true; | |
660 | } | |
661 | ||
b029d3b7 | 662 | /* Mark expression as replaceable unless stmt is volatile, or the |
48e1416a | 663 | def variable has the same root variable as something in the |
b029d3b7 | 664 | substitution list, or the def and use span a call such that |
665 | we'll expand lifetimes across a call. */ | |
9f80d051 | 666 | if (gimple_has_volatile_ops (stmt) || same_root_var |
667 | || (tab->call_cnt[ver] != cur_call_cnt | |
668 | && SINGLE_SSA_USE_OPERAND (SSA_NAME_DEF_STMT (use), SSA_OP_USE) | |
669 | == NULL_USE_OPERAND_P)) | |
bdf50f60 | 670 | finished_with_expr (tab, ver, true); |
671 | else | |
672 | mark_replaceable (tab, use, stmt_replaceable); | |
673 | } | |
674 | } | |
48e1416a | 675 | |
bdf50f60 | 676 | /* Next, see if this stmt kills off an active expression. */ |
677 | FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF) | |
678 | { | |
679 | partition = var_to_partition (map, def); | |
680 | if (partition != NO_PARTITION && tab->kill_list[partition]) | |
681 | kill_expr (tab, partition); | |
682 | } | |
683 | ||
b029d3b7 | 684 | /* Increment counter if this is a non BUILT_IN call. We allow |
685 | replacement over BUILT_IN calls since many will expand to inline | |
686 | insns instead of a true call. */ | |
687 | if (is_gimple_call (stmt) | |
688 | && !((fndecl = gimple_call_fndecl (stmt)) | |
689 | && DECL_BUILT_IN (fndecl))) | |
690 | cur_call_cnt++; | |
691 | ||
bdf50f60 | 692 | /* Now see if we are creating a new expression or not. */ |
693 | if (stmt_replaceable) | |
b029d3b7 | 694 | process_replaceable (tab, stmt, cur_call_cnt); |
bdf50f60 | 695 | |
696 | /* Free any unused dependency lists. */ | |
697 | bitmap_clear (tab->new_replaceable_dependencies); | |
698 | ||
699 | /* A V_{MAY,MUST}_DEF kills any expression using a virtual operand, | |
700 | including the current stmt. */ | |
dd277d48 | 701 | if (gimple_vdef (stmt)) |
bdf50f60 | 702 | kill_virtual_exprs (tab); |
703 | } | |
704 | } | |
705 | ||
706 | ||
707 | /* This function is the driver routine for replacement of temporary expressions | |
48e1416a | 708 | in the SSA->normal phase, operating on MAP. If there are replaceable |
709 | expressions, a table is returned which maps SSA versions to the | |
710 | expressions they should be replaced with. A NULL_TREE indicates no | |
711 | replacement should take place. If there are no replacements at all, | |
bdf50f60 | 712 | NULL is returned by the function, otherwise an expression vector indexed |
713 | by SSA_NAME version numbers. */ | |
714 | ||
4fb07d00 | 715 | bitmap |
bdf50f60 | 716 | find_replaceable_exprs (var_map map) |
717 | { | |
718 | basic_block bb; | |
719 | temp_expr_table_p table; | |
dfdbf3fd | 720 | bitmap ret; |
bdf50f60 | 721 | |
4fb07d00 | 722 | bitmap_obstack_initialize (&ter_bitmap_obstack); |
bdf50f60 | 723 | table = new_temp_expr_table (map); |
724 | FOR_EACH_BB (bb) | |
725 | { | |
726 | find_replaceable_in_bb (table, bb); | |
1b4345f7 | 727 | gcc_checking_assert (bitmap_empty_p (table->partition_in_use)); |
bdf50f60 | 728 | } |
bdf50f60 | 729 | ret = free_temp_expr_table (table); |
4fb07d00 | 730 | bitmap_obstack_release (&ter_bitmap_obstack); |
bdf50f60 | 731 | return ret; |
48e1416a | 732 | } |
bdf50f60 | 733 | |
734 | /* Dump TER expression table EXPR to file F. */ | |
735 | ||
75a70cf9 | 736 | void |
dfdbf3fd | 737 | dump_replaceable_exprs (FILE *f, bitmap expr) |
bdf50f60 | 738 | { |
75a70cf9 | 739 | tree var; |
740 | unsigned x; | |
bdf50f60 | 741 | |
742 | fprintf (f, "\nReplacing Expressions\n"); | |
75a70cf9 | 743 | for (x = 0; x < num_ssa_names; x++) |
dfdbf3fd | 744 | if (bitmap_bit_p (expr, x)) |
bdf50f60 | 745 | { |
75a70cf9 | 746 | var = ssa_name (x); |
bdf50f60 | 747 | print_generic_expr (f, var, TDF_SLIM); |
748 | fprintf (f, " replace with --> "); | |
dfdbf3fd | 749 | print_gimple_stmt (f, SSA_NAME_DEF_STMT (var), 0, TDF_SLIM); |
bdf50f60 | 750 | fprintf (f, "\n"); |
751 | } | |
752 | fprintf (f, "\n"); | |
753 | } | |
754 | ||
755 | ||
756 | #ifdef ENABLE_CHECKING | |
757 | /* Dump the status of the various tables in the expression table. This is used | |
758 | exclusively to debug TER. F is the place to send debug info and T is the | |
759 | table being debugged. */ | |
760 | ||
4b987fac | 761 | DEBUG_FUNCTION void |
bdf50f60 | 762 | debug_ter (FILE *f, temp_expr_table_p t) |
763 | { | |
764 | unsigned x, y; | |
765 | bitmap_iterator bi; | |
766 | ||
48e1416a | 767 | fprintf (f, "\nDumping current state of TER\n virtual partition = %d\n", |
bdf50f60 | 768 | VIRTUAL_PARTITION (t)); |
769 | if (t->replaceable_expressions) | |
770 | dump_replaceable_exprs (f, t->replaceable_expressions); | |
771 | fprintf (f, "Currently tracking the following expressions:\n"); | |
772 | ||
773 | for (x = 1; x < num_ssa_names; x++) | |
774 | if (t->expr_decl_uids[x]) | |
775 | { | |
b029d3b7 | 776 | print_generic_expr (f, ssa_name (x), TDF_SLIM); |
bdf50f60 | 777 | fprintf (f, " dep-parts : "); |
48e1416a | 778 | if (t->partition_dependencies[x] |
bdf50f60 | 779 | && !bitmap_empty_p (t->partition_dependencies[x])) |
780 | { | |
781 | EXECUTE_IF_SET_IN_BITMAP (t->partition_dependencies[x], 0, y, bi) | |
782 | fprintf (f, "P%d ",y); | |
783 | } | |
b029d3b7 | 784 | fprintf (f, " basedecls: "); |
bdf50f60 | 785 | EXECUTE_IF_SET_IN_BITMAP (t->expr_decl_uids[x], 0, y, bi) |
786 | fprintf (f, "%d ",y); | |
b029d3b7 | 787 | fprintf (f, " call_cnt : %d",t->call_cnt[x]); |
788 | fprintf (f, "\n"); | |
bdf50f60 | 789 | } |
790 | ||
48e1416a | 791 | bitmap_print (f, t->partition_in_use, "Partitions in use ", |
bdf50f60 | 792 | "\npartition KILL lists:\n"); |
793 | ||
794 | for (x = 0; x <= num_var_partitions (t->map); x++) | |
795 | if (t->kill_list[x]) | |
796 | { | |
797 | fprintf (f, "Partition %d : ", x); | |
798 | EXECUTE_IF_SET_IN_BITMAP (t->kill_list[x], 0, y, bi) | |
799 | fprintf (f, "_%d ",y); | |
800 | } | |
801 | ||
802 | fprintf (f, "\n----------\n"); | |
803 | } | |
804 | #endif |