1 | /* Function splitting pass |
2 | Copyright (C) 2010-2023 Free Software Foundation, Inc. |
3 | Contributed by Jan Hubicka <jh@suse.cz> |
4 | |
5 | This file is part of GCC. |
6 | |
7 | GCC is free software; you can redistribute it and/or modify it under |
8 | the terms of the GNU General Public License as published by the Free |
9 | Software Foundation; either version 3, or (at your option) any later |
10 | version. |
11 | |
12 | GCC is distributed in the hope that it will be useful, but WITHOUT ANY |
13 | WARRANTY; without even the implied warranty of MERCHANTABILITY or |
14 | FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
15 | for more details. |
16 | |
17 | You should have received a copy of the GNU General Public License |
18 | along with GCC; see the file COPYING3. If not see |
19 | <http://www.gnu.org/licenses/>. */ |
20 | |
21 | /* The purpose of this pass is to split function bodies to improve |
22 | inlining. I.e. for function of the form: |
23 | |
24 | func (...) |
25 | { |
26 | if (cheap_test) |
27 | something_small |
28 | else |
29 | something_big |
30 | } |
31 | |
32 | Produce: |
33 | |
34 | func.part (...) |
35 | { |
36 | something_big |
37 | } |
38 | |
39 | func (...) |
40 | { |
41 | if (cheap_test) |
42 | something_small |
43 | else |
44 | func.part (...); |
45 | } |
46 | |
47 | When func becomes inlinable and when cheap_test is often true, inlining func, |
48 | but not fund.part leads to performance improvement similar as inlining |
49 | original func while the code size growth is smaller. |
50 | |
51 | The pass is organized in three stages: |
52 | 1) Collect local info about basic block into BB_INFO structure and |
53 | compute function body estimated size and time. |
54 | 2) Via DFS walk find all possible basic blocks where we can split |
55 | and chose best one. |
56 | 3) If split point is found, split at the specified BB by creating a clone |
57 | and updating function to call it. |
58 | |
59 | The decisions what functions to split are in execute_split_functions |
60 | and consider_split. |
61 | |
62 | There are several possible future improvements for this pass including: |
63 | |
64 | 1) Splitting to break up large functions |
65 | 2) Splitting to reduce stack frame usage |
66 | 3) Allow split part of function to use values computed in the header part. |
67 | The values needs to be passed to split function, perhaps via same |
68 | interface as for nested functions or as argument. |
69 | 4) Support for simple rematerialization. I.e. when split part use |
70 | value computed in header from function parameter in very cheap way, we |
71 | can just recompute it. |
72 | 5) Support splitting of nested functions. |
73 | 6) Support non-SSA arguments. |
74 | 7) There is nothing preventing us from producing multiple parts of single function |
75 | when needed or splitting also the parts. */ |
76 | |
77 | #include "config.h" |
78 | #include "system.h" |
79 | #include "coretypes.h" |
80 | #include "backend.h" |
81 | #include "rtl.h" |
82 | #include "tree.h" |
83 | #include "gimple.h" |
84 | #include "cfghooks.h" |
85 | #include "alloc-pool.h" |
86 | #include "tree-pass.h" |
87 | #include "ssa.h" |
88 | #include "cgraph.h" |
89 | #include "diagnostic.h" |
90 | #include "fold-const.h" |
91 | #include "cfganal.h" |
92 | #include "calls.h" |
93 | #include "gimplify.h" |
94 | #include "gimple-iterator.h" |
95 | #include "gimplify-me.h" |
96 | #include "gimple-walk.h" |
97 | #include "symbol-summary.h" |
98 | #include "ipa-prop.h" |
99 | #include "tree-cfg.h" |
100 | #include "tree-into-ssa.h" |
101 | #include "tree-dfa.h" |
102 | #include "tree-inline.h" |
103 | #include "gimple-pretty-print.h" |
104 | #include "ipa-fnsummary.h" |
105 | #include "cfgloop.h" |
106 | #include "attribs.h" |
107 | |
108 | /* Per basic block info. */ |
109 | |
110 | class split_bb_info |
111 | { |
112 | public: |
113 | unsigned int size; |
114 | sreal time; |
115 | }; |
116 | |
117 | static vec<split_bb_info> bb_info_vec; |
118 | |
119 | /* Description of split point. */ |
120 | |
121 | class split_point |
122 | { |
123 | public: |
124 | /* Size of the partitions. */ |
125 | sreal , split_time; |
126 | unsigned int , split_size; |
127 | |
128 | /* SSA names that need to be passed into spit function. */ |
129 | bitmap ssa_names_to_pass; |
130 | |
131 | /* Basic block where we split (that will become entry point of new function. */ |
132 | basic_block entry_bb; |
133 | |
134 | /* Count for entering the split part. |
135 | This is not count of the entry_bb because it may be in loop. */ |
136 | profile_count count; |
137 | |
138 | /* Basic blocks we are splitting away. */ |
139 | bitmap split_bbs; |
140 | |
141 | /* True when return value is computed on split part and thus it needs |
142 | to be returned. */ |
143 | bool split_part_set_retval; |
144 | }; |
145 | |
146 | /* Best split point found. */ |
147 | |
148 | class split_point best_split_point; |
149 | |
150 | /* Set of basic blocks that are not allowed to dominate a split point. */ |
151 | |
152 | static bitmap forbidden_dominators; |
153 | |
154 | static tree find_retval (basic_block return_bb); |
155 | |
156 | /* Callback for walk_stmt_load_store_addr_ops. If T is non-SSA automatic |
157 | variable, check it if it is present in bitmap passed via DATA. */ |
158 | |
159 | static bool |
160 | test_nonssa_use (gimple *, tree t, tree, void *data) |
161 | { |
162 | t = get_base_address (t); |
163 | |
164 | if (!t || is_gimple_reg (t)) |
165 | return false; |
166 | |
167 | if (TREE_CODE (t) == PARM_DECL |
168 | || (VAR_P (t) |
169 | && auto_var_in_fn_p (t, current_function_decl)) |
170 | || TREE_CODE (t) == RESULT_DECL |
171 | /* Normal labels are part of CFG and will be handled gratefully. |
172 | Forced labels however can be used directly by statements and |
173 | need to stay in one partition along with their uses. */ |
174 | || (TREE_CODE (t) == LABEL_DECL |
175 | && FORCED_LABEL (t))) |
176 | return bitmap_bit_p ((bitmap)data, DECL_UID (t)); |
177 | |
178 | /* For DECL_BY_REFERENCE, the return value is actually a pointer. We want |
179 | to pretend that the value pointed to is actual result decl. */ |
180 | if ((TREE_CODE (t) == MEM_REF || INDIRECT_REF_P (t)) |
181 | && TREE_CODE (TREE_OPERAND (t, 0)) == SSA_NAME |
182 | && SSA_NAME_VAR (TREE_OPERAND (t, 0)) |
183 | && TREE_CODE (SSA_NAME_VAR (TREE_OPERAND (t, 0))) == RESULT_DECL |
184 | && DECL_BY_REFERENCE (DECL_RESULT (current_function_decl))) |
185 | return |
186 | bitmap_bit_p ((bitmap)data, |
187 | DECL_UID (DECL_RESULT (current_function_decl))); |
188 | |
189 | return false; |
190 | } |
191 | |
192 | /* Dump split point CURRENT. */ |
193 | |
194 | static void |
195 | dump_split_point (FILE * file, class split_point *current) |
196 | { |
197 | fprintf (stream: file, |
198 | format: "Split point at BB %i\n" |
199 | " header time: %f header size: %i\n" |
200 | " split time: %f split size: %i\n bbs: " , |
201 | current->entry_bb->index, current->header_time.to_double (), |
202 | current->header_size, current->split_time.to_double (), |
203 | current->split_size); |
204 | dump_bitmap (file, map: current->split_bbs); |
205 | fprintf (stream: file, format: " SSA names to pass: " ); |
206 | dump_bitmap (file, map: current->ssa_names_to_pass); |
207 | } |
208 | |
209 | /* Look for all BBs in header that might lead to the split part and verify |
210 | that they are not defining any non-SSA var used by the split part. |
211 | Parameters are the same as for consider_split. */ |
212 | |
213 | static bool |
214 | verify_non_ssa_vars (class split_point *current, bitmap non_ssa_vars, |
215 | basic_block return_bb) |
216 | { |
217 | bitmap seen = BITMAP_ALLOC (NULL); |
218 | vec<basic_block> worklist = vNULL; |
219 | edge e; |
220 | edge_iterator ei; |
221 | bool ok = true; |
222 | basic_block bb; |
223 | |
224 | FOR_EACH_EDGE (e, ei, current->entry_bb->preds) |
225 | if (e->src != ENTRY_BLOCK_PTR_FOR_FN (cfun) |
226 | && !bitmap_bit_p (current->split_bbs, e->src->index)) |
227 | { |
228 | worklist.safe_push (obj: e->src); |
229 | bitmap_set_bit (seen, e->src->index); |
230 | } |
231 | |
232 | while (!worklist.is_empty ()) |
233 | { |
234 | bb = worklist.pop (); |
235 | FOR_EACH_EDGE (e, ei, bb->preds) |
236 | if (e->src != ENTRY_BLOCK_PTR_FOR_FN (cfun) |
237 | && bitmap_set_bit (seen, e->src->index)) |
238 | { |
239 | gcc_checking_assert (!bitmap_bit_p (current->split_bbs, |
240 | e->src->index)); |
241 | worklist.safe_push (obj: e->src); |
242 | } |
243 | for (gimple_stmt_iterator bsi = gsi_start_bb (bb); !gsi_end_p (i: bsi); |
244 | gsi_next (i: &bsi)) |
245 | { |
246 | gimple *stmt = gsi_stmt (i: bsi); |
247 | if (is_gimple_debug (gs: stmt)) |
248 | continue; |
249 | if (walk_stmt_load_store_addr_ops |
250 | (stmt, non_ssa_vars, test_nonssa_use, test_nonssa_use, |
251 | test_nonssa_use)) |
252 | { |
253 | ok = false; |
254 | goto done; |
255 | } |
256 | if (glabel *label_stmt = dyn_cast <glabel *> (p: stmt)) |
257 | if (test_nonssa_use (stmt, t: gimple_label_label (gs: label_stmt), |
258 | NULL_TREE, data: non_ssa_vars)) |
259 | { |
260 | ok = false; |
261 | goto done; |
262 | } |
263 | } |
264 | for (gphi_iterator bsi = gsi_start_phis (bb); !gsi_end_p (i: bsi); |
265 | gsi_next (i: &bsi)) |
266 | { |
267 | if (walk_stmt_load_store_addr_ops |
268 | (gsi_stmt (i: bsi), non_ssa_vars, test_nonssa_use, test_nonssa_use, |
269 | test_nonssa_use)) |
270 | { |
271 | ok = false; |
272 | goto done; |
273 | } |
274 | } |
275 | FOR_EACH_EDGE (e, ei, bb->succs) |
276 | { |
277 | if (e->dest != return_bb) |
278 | continue; |
279 | for (gphi_iterator bsi = gsi_start_phis (return_bb); |
280 | !gsi_end_p (i: bsi); |
281 | gsi_next (i: &bsi)) |
282 | { |
283 | gphi *stmt = bsi.phi (); |
284 | tree op = gimple_phi_arg_def (gs: stmt, index: e->dest_idx); |
285 | |
286 | if (virtual_operand_p (op: gimple_phi_result (gs: stmt))) |
287 | continue; |
288 | if (TREE_CODE (op) != SSA_NAME |
289 | && test_nonssa_use (stmt, t: op, op, data: non_ssa_vars)) |
290 | { |
291 | ok = false; |
292 | goto done; |
293 | } |
294 | } |
295 | } |
296 | } |
297 | |
298 | /* Verify that the rest of function does not define any label |
299 | used by the split part. */ |
300 | FOR_EACH_BB_FN (bb, cfun) |
301 | if (!bitmap_bit_p (current->split_bbs, bb->index) |
302 | && !bitmap_bit_p (seen, bb->index)) |
303 | { |
304 | gimple_stmt_iterator bsi; |
305 | for (bsi = gsi_start_bb (bb); !gsi_end_p (i: bsi); gsi_next (i: &bsi)) |
306 | if (glabel *label_stmt = dyn_cast <glabel *> (p: gsi_stmt (i: bsi))) |
307 | { |
308 | if (test_nonssa_use (label_stmt, |
309 | t: gimple_label_label (gs: label_stmt), |
310 | NULL_TREE, data: non_ssa_vars)) |
311 | { |
312 | ok = false; |
313 | goto done; |
314 | } |
315 | } |
316 | else |
317 | break; |
318 | } |
319 | |
320 | done: |
321 | BITMAP_FREE (seen); |
322 | worklist.release (); |
323 | return ok; |
324 | } |
325 | |
326 | /* If STMT is a call, check the callee against a list of forbidden |
327 | predicate functions. If a match is found, look for uses of the |
328 | call result in condition statements that compare against zero. |
329 | For each such use, find the block targeted by the condition |
330 | statement for the nonzero result, and set the bit for this block |
331 | in the forbidden dominators bitmap. The purpose of this is to avoid |
332 | selecting a split point where we are likely to lose the chance |
333 | to optimize away an unused function call. */ |
334 | |
335 | static void |
336 | check_forbidden_calls (gimple *stmt) |
337 | { |
338 | imm_use_iterator use_iter; |
339 | use_operand_p use_p; |
340 | tree lhs; |
341 | |
342 | /* At the moment, __builtin_constant_p is the only forbidden |
343 | predicate function call (see PR49642). */ |
344 | if (!gimple_call_builtin_p (stmt, BUILT_IN_CONSTANT_P)) |
345 | return; |
346 | |
347 | lhs = gimple_call_lhs (gs: stmt); |
348 | |
349 | if (!lhs || TREE_CODE (lhs) != SSA_NAME) |
350 | return; |
351 | |
352 | FOR_EACH_IMM_USE_FAST (use_p, use_iter, lhs) |
353 | { |
354 | tree op1; |
355 | basic_block use_bb, forbidden_bb; |
356 | enum tree_code code; |
357 | edge true_edge, false_edge; |
358 | gcond *use_stmt; |
359 | |
360 | use_stmt = dyn_cast <gcond *> (USE_STMT (use_p)); |
361 | if (!use_stmt) |
362 | continue; |
363 | |
364 | /* Assuming canonical form for GIMPLE_COND here, with constant |
365 | in second position. */ |
366 | op1 = gimple_cond_rhs (gs: use_stmt); |
367 | code = gimple_cond_code (gs: use_stmt); |
368 | use_bb = gimple_bb (g: use_stmt); |
369 | |
370 | extract_true_false_edges_from_block (use_bb, &true_edge, &false_edge); |
371 | |
372 | /* We're only interested in comparisons that distinguish |
373 | unambiguously from zero. */ |
374 | if (!integer_zerop (op1) || code == LE_EXPR || code == GE_EXPR) |
375 | continue; |
376 | |
377 | if (code == EQ_EXPR) |
378 | forbidden_bb = false_edge->dest; |
379 | else |
380 | forbidden_bb = true_edge->dest; |
381 | |
382 | bitmap_set_bit (forbidden_dominators, forbidden_bb->index); |
383 | } |
384 | } |
385 | |
386 | /* If BB is dominated by any block in the forbidden dominators set, |
387 | return TRUE; else FALSE. */ |
388 | |
389 | static bool |
390 | dominated_by_forbidden (basic_block bb) |
391 | { |
392 | unsigned dom_bb; |
393 | bitmap_iterator bi; |
394 | |
395 | EXECUTE_IF_SET_IN_BITMAP (forbidden_dominators, 1, dom_bb, bi) |
396 | { |
397 | if (dominated_by_p (CDI_DOMINATORS, bb, |
398 | BASIC_BLOCK_FOR_FN (cfun, dom_bb))) |
399 | return true; |
400 | } |
401 | |
402 | return false; |
403 | } |
404 | |
405 | /* For give split point CURRENT and return block RETURN_BB return 1 |
406 | if ssa name VAL is set by split part and 0 otherwise. */ |
407 | static bool |
408 | split_part_set_ssa_name_p (tree val, class split_point *current, |
409 | basic_block return_bb) |
410 | { |
411 | if (TREE_CODE (val) != SSA_NAME) |
412 | return false; |
413 | |
414 | return (!SSA_NAME_IS_DEFAULT_DEF (val) |
415 | && (bitmap_bit_p (current->split_bbs, |
416 | gimple_bb (SSA_NAME_DEF_STMT (val))->index) |
417 | || gimple_bb (SSA_NAME_DEF_STMT (val)) == return_bb)); |
418 | } |
419 | |
420 | /* We found an split_point CURRENT. NON_SSA_VARS is bitmap of all non ssa |
421 | variables used and RETURN_BB is return basic block. |
422 | See if we can split function here. */ |
423 | |
424 | static void |
425 | consider_split (class split_point *current, bitmap non_ssa_vars, |
426 | basic_block return_bb) |
427 | { |
428 | tree parm; |
429 | unsigned int num_args = 0; |
430 | unsigned int call_overhead; |
431 | edge e; |
432 | edge_iterator ei; |
433 | gphi_iterator bsi; |
434 | unsigned int i; |
435 | tree retval; |
436 | bool back_edge = false; |
437 | |
438 | if (dump_file && (dump_flags & TDF_DETAILS)) |
439 | dump_split_point (file: dump_file, current); |
440 | |
441 | current->count = profile_count::zero (); |
442 | FOR_EACH_EDGE (e, ei, current->entry_bb->preds) |
443 | { |
444 | if (e->flags & EDGE_DFS_BACK) |
445 | back_edge = true; |
446 | if (!bitmap_bit_p (current->split_bbs, e->src->index)) |
447 | current->count += e->count (); |
448 | } |
449 | |
450 | /* Do not split when we would end up calling function anyway. |
451 | Compares are three state, use !(...<...) to also give up when outcome |
452 | is unknown. */ |
453 | if (!(current->count |
454 | < (ENTRY_BLOCK_PTR_FOR_FN (cfun)->count.apply_scale |
455 | (param_partial_inlining_entry_probability, den: 100)))) |
456 | { |
457 | /* When profile is guessed, we cannot expect it to give us |
458 | realistic estimate on likeliness of function taking the |
459 | complex path. As a special case, when tail of the function is |
460 | a loop, enable splitting since inlining code skipping the loop |
461 | is likely noticeable win. */ |
462 | if (back_edge |
463 | && profile_status_for_fn (cfun) != PROFILE_READ |
464 | && current->count |
465 | < ENTRY_BLOCK_PTR_FOR_FN (cfun)->count) |
466 | { |
467 | if (dump_file && (dump_flags & TDF_DETAILS)) |
468 | { |
469 | fprintf (stream: dump_file, |
470 | format: " Split before loop, accepting despite low counts" ); |
471 | current->count.dump (f: dump_file); |
472 | fprintf (stream: dump_file, format: " " ); |
473 | ENTRY_BLOCK_PTR_FOR_FN (cfun)->count.dump (f: dump_file); |
474 | } |
475 | } |
476 | else |
477 | { |
478 | if (dump_file && (dump_flags & TDF_DETAILS)) |
479 | fprintf (stream: dump_file, |
480 | format: " Refused: incoming frequency is too large.\n" ); |
481 | return; |
482 | } |
483 | } |
484 | |
485 | if (!current->header_size) |
486 | { |
487 | if (dump_file && (dump_flags & TDF_DETAILS)) |
488 | fprintf (stream: dump_file, format: " Refused: header empty\n" ); |
489 | return; |
490 | } |
491 | |
492 | /* Verify that PHI args on entry are either virtual or all their operands |
493 | incoming from header are the same. */ |
494 | for (bsi = gsi_start_phis (current->entry_bb); !gsi_end_p (i: bsi); gsi_next (i: &bsi)) |
495 | { |
496 | gphi *stmt = bsi.phi (); |
497 | tree val = NULL; |
498 | |
499 | if (virtual_operand_p (op: gimple_phi_result (gs: stmt))) |
500 | continue; |
501 | for (i = 0; i < gimple_phi_num_args (gs: stmt); i++) |
502 | { |
503 | edge e = gimple_phi_arg_edge (phi: stmt, i); |
504 | if (!bitmap_bit_p (current->split_bbs, e->src->index)) |
505 | { |
506 | tree edge_val = gimple_phi_arg_def (gs: stmt, index: i); |
507 | if (val && edge_val != val) |
508 | { |
509 | if (dump_file && (dump_flags & TDF_DETAILS)) |
510 | fprintf (stream: dump_file, |
511 | format: " Refused: entry BB has PHI with multiple variants\n" ); |
512 | return; |
513 | } |
514 | val = edge_val; |
515 | } |
516 | } |
517 | } |
518 | |
519 | |
520 | /* See what argument we will pass to the split function and compute |
521 | call overhead. */ |
522 | call_overhead = eni_size_weights.call_cost; |
523 | for (parm = DECL_ARGUMENTS (current_function_decl); parm; |
524 | parm = DECL_CHAIN (parm)) |
525 | { |
526 | if (!is_gimple_reg (parm)) |
527 | { |
528 | if (bitmap_bit_p (non_ssa_vars, DECL_UID (parm))) |
529 | { |
530 | if (dump_file && (dump_flags & TDF_DETAILS)) |
531 | fprintf (stream: dump_file, |
532 | format: " Refused: need to pass non-ssa param values\n" ); |
533 | return; |
534 | } |
535 | } |
536 | else |
537 | { |
538 | tree ddef = ssa_default_def (cfun, parm); |
539 | if (ddef |
540 | && bitmap_bit_p (current->ssa_names_to_pass, |
541 | SSA_NAME_VERSION (ddef))) |
542 | { |
543 | if (!VOID_TYPE_P (TREE_TYPE (parm))) |
544 | call_overhead += estimate_move_cost (TREE_TYPE (parm), false); |
545 | num_args++; |
546 | } |
547 | } |
548 | } |
549 | if (!VOID_TYPE_P (TREE_TYPE (TREE_TYPE (current_function_decl)))) |
550 | call_overhead += estimate_move_cost (TREE_TYPE (TREE_TYPE |
551 | (current_function_decl)), |
552 | false); |
553 | |
554 | if (current->split_size <= call_overhead) |
555 | { |
556 | if (dump_file && (dump_flags & TDF_DETAILS)) |
557 | fprintf (stream: dump_file, |
558 | format: " Refused: split size is smaller than call overhead\n" ); |
559 | return; |
560 | } |
561 | /* FIXME: The logic here is not very precise, because inliner does use |
562 | inline predicates to reduce function body size. We add 10 to anticipate |
563 | that. Next stage1 we should try to be more meaningful here. */ |
564 | if (current->header_size + call_overhead |
565 | >= (unsigned int)(DECL_DECLARED_INLINE_P (current_function_decl) |
566 | ? param_max_inline_insns_single |
567 | : param_max_inline_insns_auto) + 10) |
568 | { |
569 | if (dump_file && (dump_flags & TDF_DETAILS)) |
570 | fprintf (stream: dump_file, |
571 | format: " Refused: header size is too large for inline candidate\n" ); |
572 | return; |
573 | } |
574 | |
575 | /* Splitting functions brings the target out of comdat group; this will |
576 | lead to code duplication if the function is reused by other unit. |
577 | Limit this duplication. This is consistent with limit in tree-sra.cc |
578 | FIXME: with LTO we ought to be able to do better! */ |
579 | if (DECL_ONE_ONLY (current_function_decl) |
580 | && current->split_size >= (unsigned int) param_max_inline_insns_auto + 10) |
581 | { |
582 | if (dump_file && (dump_flags & TDF_DETAILS)) |
583 | fprintf (stream: dump_file, |
584 | format: " Refused: function is COMDAT and tail is too large\n" ); |
585 | return; |
586 | } |
587 | /* For comdat functions also reject very small tails; those will likely get |
588 | inlined back and we do not want to risk the duplication overhead. |
589 | FIXME: with LTO we ought to be able to do better! */ |
590 | if (DECL_ONE_ONLY (current_function_decl) |
591 | && current->split_size |
592 | <= (unsigned int) param_early_inlining_insns / 2) |
593 | { |
594 | if (dump_file && (dump_flags & TDF_DETAILS)) |
595 | fprintf (stream: dump_file, |
596 | format: " Refused: function is COMDAT and tail is too small\n" ); |
597 | return; |
598 | } |
599 | |
600 | /* FIXME: we currently can pass only SSA function parameters to the split |
601 | arguments. Once parm_adjustment infrastructure is supported by cloning, |
602 | we can pass more than that. */ |
603 | if (num_args != bitmap_count_bits (current->ssa_names_to_pass)) |
604 | { |
605 | |
606 | if (dump_file && (dump_flags & TDF_DETAILS)) |
607 | fprintf (stream: dump_file, |
608 | format: " Refused: need to pass non-param values\n" ); |
609 | return; |
610 | } |
611 | |
612 | /* When there are non-ssa vars used in the split region, see if they |
613 | are used in the header region. If so, reject the split. |
614 | FIXME: we can use nested function support to access both. */ |
615 | if (!bitmap_empty_p (map: non_ssa_vars) |
616 | && !verify_non_ssa_vars (current, non_ssa_vars, return_bb)) |
617 | { |
618 | if (dump_file && (dump_flags & TDF_DETAILS)) |
619 | fprintf (stream: dump_file, |
620 | format: " Refused: split part has non-ssa uses\n" ); |
621 | return; |
622 | } |
623 | |
624 | /* If the split point is dominated by a forbidden block, reject |
625 | the split. */ |
626 | if (!bitmap_empty_p (map: forbidden_dominators) |
627 | && dominated_by_forbidden (bb: current->entry_bb)) |
628 | { |
629 | if (dump_file && (dump_flags & TDF_DETAILS)) |
630 | fprintf (stream: dump_file, |
631 | format: " Refused: split point dominated by forbidden block\n" ); |
632 | return; |
633 | } |
634 | |
635 | /* See if retval used by return bb is computed by header or split part. |
636 | When it is computed by split part, we need to produce return statement |
637 | in the split part and add code to header to pass it around. |
638 | |
639 | This is bit tricky to test: |
640 | 1) When there is no return_bb or no return value, we always pass |
641 | value around. |
642 | 2) Invariants are always computed by caller. |
643 | 3) For SSA we need to look if defining statement is in header or split part |
644 | 4) For non-SSA we need to look where the var is computed. */ |
645 | retval = find_retval (return_bb); |
646 | if (!retval) |
647 | { |
648 | /* If there is a return_bb with no return value in function returning |
649 | value by reference, also make the split part return void, otherwise |
650 | we expansion would try to create a non-POD temporary, which is |
651 | invalid. */ |
652 | if (return_bb != EXIT_BLOCK_PTR_FOR_FN (cfun) |
653 | && DECL_RESULT (current_function_decl) |
654 | && DECL_BY_REFERENCE (DECL_RESULT (current_function_decl))) |
655 | current->split_part_set_retval = false; |
656 | else |
657 | current->split_part_set_retval = true; |
658 | } |
659 | else if (is_gimple_min_invariant (retval)) |
660 | current->split_part_set_retval = false; |
661 | /* Special case is value returned by reference we record as if it was non-ssa |
662 | set to result_decl. */ |
663 | else if (TREE_CODE (retval) == SSA_NAME |
664 | && SSA_NAME_VAR (retval) |
665 | && TREE_CODE (SSA_NAME_VAR (retval)) == RESULT_DECL |
666 | && DECL_BY_REFERENCE (DECL_RESULT (current_function_decl))) |
667 | current->split_part_set_retval |
668 | = bitmap_bit_p (non_ssa_vars, DECL_UID (SSA_NAME_VAR (retval))); |
669 | else if (TREE_CODE (retval) == SSA_NAME) |
670 | current->split_part_set_retval |
671 | = split_part_set_ssa_name_p (val: retval, current, return_bb); |
672 | else if (TREE_CODE (retval) == PARM_DECL) |
673 | current->split_part_set_retval = false; |
674 | else if (VAR_P (retval) |
675 | || TREE_CODE (retval) == RESULT_DECL) |
676 | current->split_part_set_retval |
677 | = bitmap_bit_p (non_ssa_vars, DECL_UID (retval)); |
678 | else |
679 | current->split_part_set_retval = true; |
680 | |
681 | /* split_function fixes up at most one PHI non-virtual PHI node in return_bb, |
682 | for the return value. If there are other PHIs, give up. */ |
683 | if (return_bb != EXIT_BLOCK_PTR_FOR_FN (cfun)) |
684 | { |
685 | gphi_iterator psi; |
686 | |
687 | for (psi = gsi_start_phis (return_bb); !gsi_end_p (i: psi); gsi_next (i: &psi)) |
688 | if (!virtual_operand_p (op: gimple_phi_result (gs: psi.phi ())) |
689 | && !(retval |
690 | && current->split_part_set_retval |
691 | && TREE_CODE (retval) == SSA_NAME |
692 | && !DECL_BY_REFERENCE (DECL_RESULT (current_function_decl)) |
693 | && SSA_NAME_DEF_STMT (retval) == psi.phi ())) |
694 | { |
695 | if (dump_file && (dump_flags & TDF_DETAILS)) |
696 | fprintf (stream: dump_file, |
697 | format: " Refused: return bb has extra PHIs\n" ); |
698 | return; |
699 | } |
700 | } |
701 | |
702 | if (dump_file && (dump_flags & TDF_DETAILS)) |
703 | fprintf (stream: dump_file, format: " Accepted!\n" ); |
704 | |
705 | /* At the moment chose split point with lowest count and that leaves |
706 | out smallest size of header. |
707 | In future we might re-consider this heuristics. */ |
708 | if (!best_split_point.split_bbs |
709 | || best_split_point.count |
710 | > current->count |
711 | || (best_split_point.count == current->count |
712 | && best_split_point.split_size < current->split_size)) |
713 | |
714 | { |
715 | if (dump_file && (dump_flags & TDF_DETAILS)) |
716 | fprintf (stream: dump_file, format: " New best split point!\n" ); |
717 | if (best_split_point.ssa_names_to_pass) |
718 | { |
719 | BITMAP_FREE (best_split_point.ssa_names_to_pass); |
720 | BITMAP_FREE (best_split_point.split_bbs); |
721 | } |
722 | best_split_point = *current; |
723 | best_split_point.ssa_names_to_pass = BITMAP_ALLOC (NULL); |
724 | bitmap_copy (best_split_point.ssa_names_to_pass, |
725 | current->ssa_names_to_pass); |
726 | best_split_point.split_bbs = BITMAP_ALLOC (NULL); |
727 | bitmap_copy (best_split_point.split_bbs, current->split_bbs); |
728 | } |
729 | } |
730 | |
731 | /* Return basic block containing RETURN statement. We allow basic blocks |
732 | of the form: |
733 | <retval> = tmp_var; |
734 | return <retval> |
735 | but return_bb cannot be more complex than this (except for |
736 | -fsanitize=thread we allow TSAN_FUNC_EXIT () internal call in there). |
737 | If nothing is found, return the exit block. |
738 | |
739 | When there are multiple RETURN statement, chose one with return value, |
740 | since that one is more likely shared by multiple code paths. |
741 | |
742 | Return BB is special, because for function splitting it is the only |
743 | basic block that is duplicated in between header and split part of the |
744 | function. |
745 | |
746 | TODO: We might support multiple return blocks. */ |
747 | |
748 | static basic_block |
749 | find_return_bb (void) |
750 | { |
751 | edge e; |
752 | basic_block return_bb = EXIT_BLOCK_PTR_FOR_FN (cfun); |
753 | gimple_stmt_iterator bsi; |
754 | bool found_return = false; |
755 | tree retval = NULL_TREE; |
756 | |
757 | if (!single_pred_p (EXIT_BLOCK_PTR_FOR_FN (cfun))) |
758 | return return_bb; |
759 | |
760 | e = single_pred_edge (EXIT_BLOCK_PTR_FOR_FN (cfun)); |
761 | for (bsi = gsi_last_bb (bb: e->src); !gsi_end_p (i: bsi); gsi_prev (i: &bsi)) |
762 | { |
763 | gimple *stmt = gsi_stmt (i: bsi); |
764 | if (gimple_code (g: stmt) == GIMPLE_LABEL |
765 | || is_gimple_debug (gs: stmt) |
766 | || gimple_clobber_p (s: stmt)) |
767 | ; |
768 | else if (gimple_code (g: stmt) == GIMPLE_ASSIGN |
769 | && found_return |
770 | && gimple_assign_single_p (gs: stmt) |
771 | && (auto_var_in_fn_p (gimple_assign_rhs1 (gs: stmt), |
772 | current_function_decl) |
773 | || is_gimple_min_invariant (gimple_assign_rhs1 (gs: stmt))) |
774 | && retval == gimple_assign_lhs (gs: stmt)) |
775 | ; |
776 | else if (greturn *return_stmt = dyn_cast <greturn *> (p: stmt)) |
777 | { |
778 | found_return = true; |
779 | retval = gimple_return_retval (gs: return_stmt); |
780 | } |
781 | /* For -fsanitize=thread, allow also TSAN_FUNC_EXIT () in the return |
782 | bb. */ |
783 | else if ((flag_sanitize & SANITIZE_THREAD) |
784 | && gimple_call_internal_p (gs: stmt, fn: IFN_TSAN_FUNC_EXIT)) |
785 | ; |
786 | else |
787 | break; |
788 | } |
789 | if (gsi_end_p (i: bsi) && found_return) |
790 | return_bb = e->src; |
791 | |
792 | return return_bb; |
793 | } |
794 | |
795 | /* Given return basic block RETURN_BB, see where return value is really |
796 | stored. */ |
797 | static tree |
798 | find_retval (basic_block return_bb) |
799 | { |
800 | gimple_stmt_iterator bsi; |
801 | for (bsi = gsi_start_bb (bb: return_bb); !gsi_end_p (i: bsi); gsi_next (i: &bsi)) |
802 | if (greturn *return_stmt = dyn_cast <greturn *> (p: gsi_stmt (i: bsi))) |
803 | return gimple_return_retval (gs: return_stmt); |
804 | else if (gimple_code (g: gsi_stmt (i: bsi)) == GIMPLE_ASSIGN |
805 | && !gimple_clobber_p (s: gsi_stmt (i: bsi))) |
806 | return gimple_assign_rhs1 (gs: gsi_stmt (i: bsi)); |
807 | return NULL; |
808 | } |
809 | |
810 | /* Callback for walk_stmt_load_store_addr_ops. If T is non-SSA automatic |
811 | variable, mark it as used in bitmap passed via DATA. |
812 | Return true when access to T prevents splitting the function. */ |
813 | |
814 | static bool |
815 | mark_nonssa_use (gimple *, tree t, tree, void *data) |
816 | { |
817 | t = get_base_address (t); |
818 | |
819 | if (!t || is_gimple_reg (t)) |
820 | return false; |
821 | |
822 | /* At present we can't pass non-SSA arguments to split function. |
823 | FIXME: this can be relaxed by passing references to arguments. */ |
824 | if (TREE_CODE (t) == PARM_DECL) |
825 | { |
826 | if (dump_file && (dump_flags & TDF_DETAILS)) |
827 | fprintf (stream: dump_file, |
828 | format: "Cannot split: use of non-ssa function parameter.\n" ); |
829 | return true; |
830 | } |
831 | |
832 | if ((VAR_P (t) && auto_var_in_fn_p (t, current_function_decl)) |
833 | || TREE_CODE (t) == RESULT_DECL |
834 | || (TREE_CODE (t) == LABEL_DECL && FORCED_LABEL (t))) |
835 | bitmap_set_bit ((bitmap)data, DECL_UID (t)); |
836 | |
837 | /* For DECL_BY_REFERENCE, the return value is actually a pointer. We want |
838 | to pretend that the value pointed to is actual result decl. */ |
839 | if ((TREE_CODE (t) == MEM_REF || INDIRECT_REF_P (t)) |
840 | && TREE_CODE (TREE_OPERAND (t, 0)) == SSA_NAME |
841 | && SSA_NAME_VAR (TREE_OPERAND (t, 0)) |
842 | && TREE_CODE (SSA_NAME_VAR (TREE_OPERAND (t, 0))) == RESULT_DECL |
843 | && DECL_BY_REFERENCE (DECL_RESULT (current_function_decl))) |
844 | return |
845 | bitmap_bit_p ((bitmap)data, |
846 | DECL_UID (DECL_RESULT (current_function_decl))); |
847 | |
848 | return false; |
849 | } |
850 | |
851 | /* Compute local properties of basic block BB we collect when looking for |
852 | split points. We look for ssa defs and store them in SET_SSA_NAMES, |
853 | for ssa uses and store them in USED_SSA_NAMES and for any non-SSA automatic |
854 | vars stored in NON_SSA_VARS. |
855 | |
856 | When BB has edge to RETURN_BB, collect uses in RETURN_BB too. |
857 | |
858 | Return false when BB contains something that prevents it from being put into |
859 | split function. */ |
860 | |
861 | static bool |
862 | visit_bb (basic_block bb, basic_block return_bb, |
863 | bitmap set_ssa_names, bitmap used_ssa_names, |
864 | bitmap non_ssa_vars) |
865 | { |
866 | edge e; |
867 | edge_iterator ei; |
868 | bool can_split = true; |
869 | |
870 | for (gimple_stmt_iterator bsi = gsi_start_bb (bb); !gsi_end_p (i: bsi); |
871 | gsi_next (i: &bsi)) |
872 | { |
873 | gimple *stmt = gsi_stmt (i: bsi); |
874 | tree op; |
875 | ssa_op_iter iter; |
876 | |
877 | if (is_gimple_debug (gs: stmt)) |
878 | continue; |
879 | |
880 | if (gimple_clobber_p (s: stmt)) |
881 | continue; |
882 | |
883 | /* FIXME: We can split regions containing EH. We cannot however |
884 | split RESX, EH_DISPATCH and EH_POINTER referring to same region |
885 | into different partitions. This would require tracking of |
886 | EH regions and checking in consider_split_point if they |
887 | are not used elsewhere. */ |
888 | if (gimple_code (g: stmt) == GIMPLE_RESX) |
889 | { |
890 | if (dump_file && (dump_flags & TDF_DETAILS)) |
891 | fprintf (stream: dump_file, format: "Cannot split: resx.\n" ); |
892 | can_split = false; |
893 | } |
894 | if (gimple_code (g: stmt) == GIMPLE_EH_DISPATCH) |
895 | { |
896 | if (dump_file && (dump_flags & TDF_DETAILS)) |
897 | fprintf (stream: dump_file, format: "Cannot split: eh dispatch.\n" ); |
898 | can_split = false; |
899 | } |
900 | |
901 | /* Check calls that would prevent splitting. */ |
902 | if (gimple_code (g: stmt) == GIMPLE_CALL) |
903 | { |
904 | if (tree decl = gimple_call_fndecl (gs: stmt)) |
905 | { |
906 | /* Check builtins that would prevent splitting. */ |
907 | if (fndecl_built_in_p (node: decl, klass: BUILT_IN_NORMAL)) |
908 | switch (DECL_FUNCTION_CODE (decl)) |
909 | { |
910 | /* FIXME: once we will allow passing non-parm values to |
911 | split part, we need to be sure to handle correct |
912 | builtin_stack_save and builtin_stack_restore. At the |
913 | moment we are safe; there is no way to store |
914 | builtin_stack_save result in non-SSA variable since all |
915 | calls to those are compiler generated. */ |
916 | case BUILT_IN_APPLY: |
917 | case BUILT_IN_APPLY_ARGS: |
918 | case BUILT_IN_VA_START: |
919 | if (dump_file && (dump_flags & TDF_DETAILS)) |
920 | fprintf (stream: dump_file, |
921 | format: "Cannot split: builtin_apply and va_start.\n" ); |
922 | can_split = false; |
923 | break; |
924 | case BUILT_IN_EH_POINTER: |
925 | if (dump_file && (dump_flags & TDF_DETAILS)) |
926 | fprintf (stream: dump_file, |
927 | format: "Cannot split: builtin_eh_pointer.\n" ); |
928 | can_split = false; |
929 | break; |
930 | default: |
931 | break; |
932 | } |
933 | |
934 | /* Calls to functions (which have the warning or error |
935 | attribute on them) should not be split off into another |
936 | function. */ |
937 | if (lookup_attribute (attr_name: "warning" , DECL_ATTRIBUTES (decl)) |
938 | || lookup_attribute (attr_name: "error" , DECL_ATTRIBUTES (decl))) |
939 | { |
940 | if (dump_file && (dump_flags & TDF_DETAILS)) |
941 | fprintf (stream: dump_file, |
942 | format: "Cannot split: warning or error attribute.\n" ); |
943 | can_split = false; |
944 | } |
945 | } |
946 | } |
947 | |
948 | FOR_EACH_SSA_TREE_OPERAND (op, stmt, iter, SSA_OP_DEF) |
949 | bitmap_set_bit (set_ssa_names, SSA_NAME_VERSION (op)); |
950 | FOR_EACH_SSA_TREE_OPERAND (op, stmt, iter, SSA_OP_USE) |
951 | bitmap_set_bit (used_ssa_names, SSA_NAME_VERSION (op)); |
952 | can_split &= !walk_stmt_load_store_addr_ops (stmt, non_ssa_vars, |
953 | mark_nonssa_use, |
954 | mark_nonssa_use, |
955 | mark_nonssa_use); |
956 | } |
957 | for (gphi_iterator bsi = gsi_start_phis (bb); !gsi_end_p (i: bsi); |
958 | gsi_next (i: &bsi)) |
959 | { |
960 | gphi *stmt = bsi.phi (); |
961 | unsigned int i; |
962 | |
963 | if (virtual_operand_p (op: gimple_phi_result (gs: stmt))) |
964 | continue; |
965 | bitmap_set_bit (set_ssa_names, |
966 | SSA_NAME_VERSION (gimple_phi_result (stmt))); |
967 | for (i = 0; i < gimple_phi_num_args (gs: stmt); i++) |
968 | { |
969 | tree op = gimple_phi_arg_def (gs: stmt, index: i); |
970 | if (TREE_CODE (op) == SSA_NAME) |
971 | bitmap_set_bit (used_ssa_names, SSA_NAME_VERSION (op)); |
972 | } |
973 | can_split &= !walk_stmt_load_store_addr_ops (stmt, non_ssa_vars, |
974 | mark_nonssa_use, |
975 | mark_nonssa_use, |
976 | mark_nonssa_use); |
977 | } |
978 | /* Record also uses coming from PHI operand in return BB. */ |
979 | FOR_EACH_EDGE (e, ei, bb->succs) |
980 | if (e->dest == return_bb) |
981 | { |
982 | for (gphi_iterator bsi = gsi_start_phis (return_bb); |
983 | !gsi_end_p (i: bsi); |
984 | gsi_next (i: &bsi)) |
985 | { |
986 | gphi *stmt = bsi.phi (); |
987 | tree op = gimple_phi_arg_def (gs: stmt, index: e->dest_idx); |
988 | |
989 | if (virtual_operand_p (op: gimple_phi_result (gs: stmt))) |
990 | continue; |
991 | if (TREE_CODE (op) == SSA_NAME) |
992 | bitmap_set_bit (used_ssa_names, SSA_NAME_VERSION (op)); |
993 | else |
994 | can_split &= !mark_nonssa_use (stmt, t: op, op, data: non_ssa_vars); |
995 | } |
996 | } |
997 | return can_split; |
998 | } |
999 | |
1000 | /* Stack entry for recursive DFS walk in find_split_point. */ |
1001 | |
1002 | class stack_entry |
1003 | { |
1004 | public: |
1005 | /* Basic block we are examining. */ |
1006 | basic_block bb; |
1007 | |
1008 | /* SSA names set and used by the BB and all BBs reachable |
1009 | from it via DFS walk. */ |
1010 | bitmap set_ssa_names, used_ssa_names; |
1011 | bitmap non_ssa_vars; |
1012 | |
1013 | /* All BBS visited from this BB via DFS walk. */ |
1014 | bitmap bbs_visited; |
1015 | |
1016 | /* Last examined edge in DFS walk. Since we walk unoriented graph, |
1017 | the value is up to sum of incoming and outgoing edges of BB. */ |
1018 | unsigned int edge_num; |
1019 | |
1020 | /* Stack entry index of earliest BB reachable from current BB |
1021 | or any BB visited later in DFS walk. */ |
1022 | int earliest; |
1023 | |
1024 | /* Overall time and size of all BBs reached from this BB in DFS walk. */ |
1025 | sreal overall_time; |
1026 | int overall_size; |
1027 | |
1028 | /* When false we cannot split on this BB. */ |
1029 | bool can_split; |
1030 | }; |
1031 | |
1032 | |
1033 | /* Find all articulations and call consider_split on them. |
1034 | OVERALL_TIME and OVERALL_SIZE is time and size of the function. |
1035 | |
1036 | We perform basic algorithm for finding an articulation in a graph |
1037 | created from CFG by considering it to be an unoriented graph. |
1038 | |
1039 | The articulation is discovered via DFS walk. We collect earliest |
1040 | basic block on stack that is reachable via backward edge. Articulation |
1041 | is any basic block such that there is no backward edge bypassing it. |
1042 | To reduce stack usage we maintain heap allocated stack in STACK vector. |
1043 | AUX pointer of BB is set to index it appears in the stack or -1 once |
1044 | it is visited and popped off the stack. |
1045 | |
1046 | The algorithm finds articulation after visiting the whole component |
1047 | reachable by it. This makes it convenient to collect information about |
1048 | the component used by consider_split. */ |
1049 | |
1050 | static void |
1051 | find_split_points (basic_block return_bb, sreal overall_time, int overall_size) |
1052 | { |
1053 | stack_entry first; |
1054 | vec<stack_entry> stack = vNULL; |
1055 | basic_block bb; |
1056 | class split_point current; |
1057 | |
1058 | current.header_time = overall_time; |
1059 | current.header_size = overall_size; |
1060 | current.split_time = 0; |
1061 | current.split_size = 0; |
1062 | current.ssa_names_to_pass = BITMAP_ALLOC (NULL); |
1063 | |
1064 | first.bb = ENTRY_BLOCK_PTR_FOR_FN (cfun); |
1065 | first.edge_num = 0; |
1066 | first.overall_time = 0; |
1067 | first.overall_size = 0; |
1068 | first.earliest = INT_MAX; |
1069 | first.set_ssa_names = 0; |
1070 | first.used_ssa_names = 0; |
1071 | first.non_ssa_vars = 0; |
1072 | first.bbs_visited = 0; |
1073 | first.can_split = false; |
1074 | stack.safe_push (obj: first); |
1075 | ENTRY_BLOCK_PTR_FOR_FN (cfun)->aux = (void *)(intptr_t)-1; |
1076 | |
1077 | while (!stack.is_empty ()) |
1078 | { |
1079 | stack_entry *entry = &stack.last (); |
1080 | |
1081 | /* We are walking an acyclic graph, so edge_num counts |
1082 | succ and pred edges together. However when considering |
1083 | articulation, we want to have processed everything reachable |
1084 | from articulation but nothing that reaches into it. */ |
1085 | if (entry->edge_num == EDGE_COUNT (entry->bb->succs) |
1086 | && entry->bb != ENTRY_BLOCK_PTR_FOR_FN (cfun)) |
1087 | { |
1088 | int pos = stack.length (); |
1089 | entry->can_split &= visit_bb (bb: entry->bb, return_bb, |
1090 | set_ssa_names: entry->set_ssa_names, |
1091 | used_ssa_names: entry->used_ssa_names, |
1092 | non_ssa_vars: entry->non_ssa_vars); |
1093 | if (pos <= entry->earliest && !entry->can_split |
1094 | && dump_file && (dump_flags & TDF_DETAILS)) |
1095 | fprintf (stream: dump_file, |
1096 | format: "found articulation at bb %i but cannot split\n" , |
1097 | entry->bb->index); |
1098 | if (pos <= entry->earliest && entry->can_split) |
1099 | { |
1100 | if (dump_file && (dump_flags & TDF_DETAILS)) |
1101 | fprintf (stream: dump_file, format: "found articulation at bb %i\n" , |
1102 | entry->bb->index); |
1103 | current.entry_bb = entry->bb; |
1104 | current.ssa_names_to_pass = BITMAP_ALLOC (NULL); |
1105 | bitmap_and_compl (current.ssa_names_to_pass, |
1106 | entry->used_ssa_names, entry->set_ssa_names); |
1107 | current.header_time = overall_time - entry->overall_time; |
1108 | current.header_size = overall_size - entry->overall_size; |
1109 | current.split_time = entry->overall_time; |
1110 | current.split_size = entry->overall_size; |
1111 | current.split_bbs = entry->bbs_visited; |
1112 | consider_split (current: ¤t, non_ssa_vars: entry->non_ssa_vars, return_bb); |
1113 | BITMAP_FREE (current.ssa_names_to_pass); |
1114 | } |
1115 | } |
1116 | /* Do actual DFS walk. */ |
1117 | if (entry->edge_num |
1118 | < (EDGE_COUNT (entry->bb->succs) |
1119 | + EDGE_COUNT (entry->bb->preds))) |
1120 | { |
1121 | edge e; |
1122 | basic_block dest; |
1123 | if (entry->edge_num < EDGE_COUNT (entry->bb->succs)) |
1124 | { |
1125 | e = EDGE_SUCC (entry->bb, entry->edge_num); |
1126 | dest = e->dest; |
1127 | } |
1128 | else |
1129 | { |
1130 | e = EDGE_PRED (entry->bb, entry->edge_num |
1131 | - EDGE_COUNT (entry->bb->succs)); |
1132 | dest = e->src; |
1133 | } |
1134 | |
1135 | entry->edge_num++; |
1136 | |
1137 | /* New BB to visit, push it to the stack. */ |
1138 | if (dest != return_bb && dest != EXIT_BLOCK_PTR_FOR_FN (cfun) |
1139 | && !dest->aux) |
1140 | { |
1141 | stack_entry new_entry; |
1142 | |
1143 | new_entry.bb = dest; |
1144 | new_entry.edge_num = 0; |
1145 | new_entry.overall_time |
1146 | = bb_info_vec[dest->index].time; |
1147 | new_entry.overall_size |
1148 | = bb_info_vec[dest->index].size; |
1149 | new_entry.earliest = INT_MAX; |
1150 | new_entry.set_ssa_names = BITMAP_ALLOC (NULL); |
1151 | new_entry.used_ssa_names = BITMAP_ALLOC (NULL); |
1152 | new_entry.bbs_visited = BITMAP_ALLOC (NULL); |
1153 | new_entry.non_ssa_vars = BITMAP_ALLOC (NULL); |
1154 | new_entry.can_split = true; |
1155 | bitmap_set_bit (new_entry.bbs_visited, dest->index); |
1156 | stack.safe_push (obj: new_entry); |
1157 | dest->aux = (void *)(intptr_t)stack.length (); |
1158 | } |
1159 | /* Back edge found, record the earliest point. */ |
1160 | else if ((intptr_t)dest->aux > 0 |
1161 | && (intptr_t)dest->aux < entry->earliest) |
1162 | entry->earliest = (intptr_t)dest->aux; |
1163 | } |
1164 | /* We are done with examining the edges. Pop off the value from stack |
1165 | and merge stuff we accumulate during the walk. */ |
1166 | else if (entry->bb != ENTRY_BLOCK_PTR_FOR_FN (cfun)) |
1167 | { |
1168 | stack_entry *prev = &stack[stack.length () - 2]; |
1169 | |
1170 | entry->bb->aux = (void *)(intptr_t)-1; |
1171 | prev->can_split &= entry->can_split; |
1172 | if (prev->set_ssa_names) |
1173 | { |
1174 | bitmap_ior_into (prev->set_ssa_names, entry->set_ssa_names); |
1175 | bitmap_ior_into (prev->used_ssa_names, entry->used_ssa_names); |
1176 | bitmap_ior_into (prev->bbs_visited, entry->bbs_visited); |
1177 | bitmap_ior_into (prev->non_ssa_vars, entry->non_ssa_vars); |
1178 | } |
1179 | if (prev->earliest > entry->earliest) |
1180 | prev->earliest = entry->earliest; |
1181 | prev->overall_time += entry->overall_time; |
1182 | prev->overall_size += entry->overall_size; |
1183 | BITMAP_FREE (entry->set_ssa_names); |
1184 | BITMAP_FREE (entry->used_ssa_names); |
1185 | BITMAP_FREE (entry->bbs_visited); |
1186 | BITMAP_FREE (entry->non_ssa_vars); |
1187 | stack.pop (); |
1188 | } |
1189 | else |
1190 | stack.pop (); |
1191 | } |
1192 | ENTRY_BLOCK_PTR_FOR_FN (cfun)->aux = NULL; |
1193 | FOR_EACH_BB_FN (bb, cfun) |
1194 | bb->aux = NULL; |
1195 | stack.release (); |
1196 | BITMAP_FREE (current.ssa_names_to_pass); |
1197 | } |
1198 | |
1199 | /* Split function at SPLIT_POINT. */ |
1200 | |
1201 | static void |
1202 | split_function (basic_block return_bb, class split_point *split_point, |
1203 | bool add_tsan_func_exit) |
1204 | { |
1205 | vec<tree> args_to_pass = vNULL; |
1206 | bitmap args_to_skip; |
1207 | tree parm; |
1208 | int num = 0; |
1209 | cgraph_node *node, *cur_node = cgraph_node::get (decl: current_function_decl); |
1210 | basic_block call_bb; |
1211 | gcall *call, *tsan_func_exit_call = NULL; |
1212 | edge e; |
1213 | edge_iterator ei; |
1214 | tree retval = NULL, real_retval = NULL; |
1215 | gimple *last_stmt = NULL; |
1216 | unsigned int i; |
1217 | tree arg, ddef; |
1218 | |
1219 | if (dump_file) |
1220 | { |
1221 | fprintf (stream: dump_file, format: "\n\nSplitting function at:\n" ); |
1222 | dump_split_point (file: dump_file, current: split_point); |
1223 | } |
1224 | |
1225 | if (cur_node->can_change_signature) |
1226 | args_to_skip = BITMAP_ALLOC (NULL); |
1227 | else |
1228 | args_to_skip = NULL; |
1229 | |
1230 | /* Collect the parameters of new function and args_to_skip bitmap. */ |
1231 | for (parm = DECL_ARGUMENTS (current_function_decl); |
1232 | parm; parm = DECL_CHAIN (parm), num++) |
1233 | if (args_to_skip |
1234 | && (!is_gimple_reg (parm) |
1235 | || (ddef = ssa_default_def (cfun, parm)) == NULL_TREE |
1236 | || !bitmap_bit_p (split_point->ssa_names_to_pass, |
1237 | SSA_NAME_VERSION (ddef)))) |
1238 | bitmap_set_bit (args_to_skip, num); |
1239 | else |
1240 | { |
1241 | /* This parm might not have been used up to now, but is going to be |
1242 | used, hence register it. */ |
1243 | if (is_gimple_reg (parm)) |
1244 | arg = get_or_create_ssa_default_def (cfun, parm); |
1245 | else |
1246 | arg = parm; |
1247 | |
1248 | if (!useless_type_conversion_p (DECL_ARG_TYPE (parm), TREE_TYPE (arg))) |
1249 | arg = fold_convert (DECL_ARG_TYPE (parm), arg); |
1250 | args_to_pass.safe_push (obj: arg); |
1251 | } |
1252 | |
1253 | /* See if the split function will return. */ |
1254 | bool split_part_return_p = false; |
1255 | FOR_EACH_EDGE (e, ei, return_bb->preds) |
1256 | { |
1257 | if (bitmap_bit_p (split_point->split_bbs, e->src->index)) |
1258 | split_part_return_p = true; |
1259 | } |
1260 | |
1261 | /* Add return block to what will become the split function. |
1262 | We do not return; no return block is needed. */ |
1263 | if (!split_part_return_p) |
1264 | ; |
1265 | /* We have no return block, so nothing is needed. */ |
1266 | else if (return_bb == EXIT_BLOCK_PTR_FOR_FN (cfun)) |
1267 | ; |
1268 | /* When we do not want to return value, we need to construct |
1269 | new return block with empty return statement. |
1270 | FIXME: Once we are able to change return type, we should change function |
1271 | to return void instead of just outputting function with undefined return |
1272 | value. For structures this affects quality of codegen. */ |
1273 | else if ((retval = find_retval (return_bb)) |
1274 | && !split_point->split_part_set_retval) |
1275 | { |
1276 | bool redirected = true; |
1277 | basic_block new_return_bb = create_basic_block (NULL, 0, return_bb); |
1278 | gimple_stmt_iterator gsi = gsi_start_bb (bb: new_return_bb); |
1279 | gsi_insert_after (&gsi, gimple_build_return (NULL), GSI_NEW_STMT); |
1280 | new_return_bb->count = profile_count::zero (); |
1281 | while (redirected) |
1282 | { |
1283 | redirected = false; |
1284 | FOR_EACH_EDGE (e, ei, return_bb->preds) |
1285 | if (bitmap_bit_p (split_point->split_bbs, e->src->index)) |
1286 | { |
1287 | new_return_bb->count += e->count (); |
1288 | redirect_edge_and_branch (e, new_return_bb); |
1289 | redirected = true; |
1290 | break; |
1291 | } |
1292 | } |
1293 | e = make_single_succ_edge (new_return_bb, EXIT_BLOCK_PTR_FOR_FN (cfun), 0); |
1294 | add_bb_to_loop (new_return_bb, current_loops->tree_root); |
1295 | bitmap_set_bit (split_point->split_bbs, new_return_bb->index); |
1296 | } |
1297 | /* When we pass around the value, use existing return block. */ |
1298 | else |
1299 | bitmap_set_bit (split_point->split_bbs, return_bb->index); |
1300 | |
1301 | /* If RETURN_BB has virtual operand PHIs, they must be removed and the |
1302 | virtual operand marked for renaming as we change the CFG in a way that |
1303 | tree-inline is not able to compensate for. |
1304 | |
1305 | Note this can happen whether or not we have a return value. If we have |
1306 | a return value, then RETURN_BB may have PHIs for real operands too. */ |
1307 | if (return_bb != EXIT_BLOCK_PTR_FOR_FN (cfun)) |
1308 | { |
1309 | bool phi_p = false; |
1310 | for (gphi_iterator gsi = gsi_start_phis (return_bb); |
1311 | !gsi_end_p (i: gsi);) |
1312 | { |
1313 | gphi *stmt = gsi.phi (); |
1314 | if (!virtual_operand_p (op: gimple_phi_result (gs: stmt))) |
1315 | { |
1316 | gsi_next (i: &gsi); |
1317 | continue; |
1318 | } |
1319 | mark_virtual_phi_result_for_renaming (stmt); |
1320 | remove_phi_node (&gsi, true); |
1321 | phi_p = true; |
1322 | } |
1323 | /* In reality we have to rename the reaching definition of the |
1324 | virtual operand at return_bb as we will eventually release it |
1325 | when we remove the code region we outlined. |
1326 | So we have to rename all immediate virtual uses of that region |
1327 | if we didn't see a PHI definition yet. */ |
1328 | /* ??? In real reality we want to set the reaching vdef of the |
1329 | entry of the SESE region as the vuse of the call and the reaching |
1330 | vdef of the exit of the SESE region as the vdef of the call. */ |
1331 | if (!phi_p) |
1332 | for (gimple_stmt_iterator gsi = gsi_start_bb (bb: return_bb); |
1333 | !gsi_end_p (i: gsi); |
1334 | gsi_next (i: &gsi)) |
1335 | { |
1336 | gimple *stmt = gsi_stmt (i: gsi); |
1337 | if (gimple_vuse (g: stmt)) |
1338 | { |
1339 | gimple_set_vuse (g: stmt, NULL_TREE); |
1340 | update_stmt (s: stmt); |
1341 | } |
1342 | if (gimple_vdef (g: stmt)) |
1343 | break; |
1344 | } |
1345 | } |
1346 | |
1347 | ipa_param_adjustments *adjustments; |
1348 | bool skip_return = (!split_part_return_p |
1349 | || !split_point->split_part_set_retval); |
1350 | /* TODO: Perhaps get rid of args_to_skip entirely, after we make sure the |
1351 | debug info generation and discrepancy avoiding works well too. */ |
1352 | if ((args_to_skip && !bitmap_empty_p (map: args_to_skip)) |
1353 | || skip_return) |
1354 | { |
1355 | vec<ipa_adjusted_param, va_gc> *new_params = NULL; |
1356 | unsigned j; |
1357 | for (parm = DECL_ARGUMENTS (current_function_decl), j = 0; |
1358 | parm; parm = DECL_CHAIN (parm), j++) |
1359 | if (!args_to_skip || !bitmap_bit_p (args_to_skip, j)) |
1360 | { |
1361 | ipa_adjusted_param adj; |
1362 | memset (s: &adj, c: 0, n: sizeof (adj)); |
1363 | adj.op = IPA_PARAM_OP_COPY; |
1364 | adj.base_index = j; |
1365 | adj.prev_clone_index = j; |
1366 | vec_safe_push (v&: new_params, obj: adj); |
1367 | } |
1368 | adjustments = new ipa_param_adjustments (new_params, j, skip_return); |
1369 | } |
1370 | else |
1371 | adjustments = NULL; |
1372 | |
1373 | /* Now create the actual clone. */ |
1374 | cgraph_edge::rebuild_edges (); |
1375 | node = cur_node->create_version_clone_with_body |
1376 | (redirect_callers: vNULL, NULL, param_adjustments: adjustments, |
1377 | bbs_to_copy: split_point->split_bbs, new_entry_block: split_point->entry_bb, clone_name: "part" ); |
1378 | delete adjustments; |
1379 | node->split_part = true; |
1380 | |
1381 | if (cur_node->same_comdat_group) |
1382 | { |
1383 | /* TODO: call is versionable if we make sure that all |
1384 | callers are inside of a comdat group. */ |
1385 | cur_node->calls_comdat_local = true; |
1386 | node->add_to_same_comdat_group (old_node: cur_node); |
1387 | } |
1388 | |
1389 | |
1390 | /* Let's take a time profile for splitted function. */ |
1391 | if (cur_node->tp_first_run) |
1392 | node->tp_first_run = cur_node->tp_first_run + 1; |
1393 | |
1394 | /* For usual cloning it is enough to clear builtin only when signature |
1395 | changes. For partial inlining we however cannot expect the part |
1396 | of builtin implementation to have same semantic as the whole. */ |
1397 | if (fndecl_built_in_p (node: node->decl)) |
1398 | set_decl_built_in_function (decl: node->decl, fclass: NOT_BUILT_IN, fcode: 0); |
1399 | |
1400 | /* If return_bb contains any clobbers that refer to SSA_NAMEs |
1401 | set in the split part, remove them. Also reset debug stmts that |
1402 | refer to SSA_NAMEs set in the split part. */ |
1403 | if (return_bb != EXIT_BLOCK_PTR_FOR_FN (cfun)) |
1404 | { |
1405 | gimple_stmt_iterator gsi = gsi_start_bb (bb: return_bb); |
1406 | while (!gsi_end_p (i: gsi)) |
1407 | { |
1408 | tree op; |
1409 | ssa_op_iter iter; |
1410 | gimple *stmt = gsi_stmt (i: gsi); |
1411 | bool remove = false; |
1412 | if (gimple_clobber_p (s: stmt) || is_gimple_debug (gs: stmt)) |
1413 | FOR_EACH_SSA_TREE_OPERAND (op, stmt, iter, SSA_OP_USE) |
1414 | { |
1415 | basic_block bb = gimple_bb (SSA_NAME_DEF_STMT (op)); |
1416 | if (op != retval |
1417 | && bb |
1418 | && bb != return_bb |
1419 | && bitmap_bit_p (split_point->split_bbs, bb->index)) |
1420 | { |
1421 | if (is_gimple_debug (gs: stmt)) |
1422 | { |
1423 | gimple_debug_bind_reset_value (dbg: stmt); |
1424 | update_stmt (s: stmt); |
1425 | } |
1426 | else |
1427 | remove = true; |
1428 | break; |
1429 | } |
1430 | } |
1431 | if (remove) |
1432 | gsi_remove (&gsi, true); |
1433 | else |
1434 | gsi_next (i: &gsi); |
1435 | } |
1436 | } |
1437 | |
1438 | /* If the original function is declared inline, there is no point in issuing |
1439 | a warning for the non-inlinable part. */ |
1440 | DECL_NO_INLINE_WARNING_P (node->decl) = 1; |
1441 | cur_node->remove_callees (); |
1442 | cur_node->remove_all_references (); |
1443 | if (!split_part_return_p) |
1444 | TREE_THIS_VOLATILE (node->decl) = 1; |
1445 | if (dump_file) |
1446 | dump_function_to_file (node->decl, dump_file, dump_flags); |
1447 | |
1448 | /* Create the basic block we place call into. It is the entry basic block |
1449 | split after last label. */ |
1450 | call_bb = split_point->entry_bb; |
1451 | for (gimple_stmt_iterator gsi = gsi_start_bb (bb: call_bb); !gsi_end_p (i: gsi);) |
1452 | if (gimple_code (g: gsi_stmt (i: gsi)) == GIMPLE_LABEL) |
1453 | { |
1454 | last_stmt = gsi_stmt (i: gsi); |
1455 | gsi_next (i: &gsi); |
1456 | } |
1457 | else |
1458 | break; |
1459 | call_bb->count = split_point->count; |
1460 | e = split_block (split_point->entry_bb, last_stmt); |
1461 | remove_edge (e); |
1462 | |
1463 | /* Produce the call statement. */ |
1464 | gimple_stmt_iterator gsi = gsi_last_bb (bb: call_bb); |
1465 | FOR_EACH_VEC_ELT (args_to_pass, i, arg) |
1466 | if (!is_gimple_val (arg)) |
1467 | { |
1468 | arg = force_gimple_operand_gsi (&gsi, arg, true, NULL_TREE, |
1469 | false, GSI_CONTINUE_LINKING); |
1470 | args_to_pass[i] = arg; |
1471 | } |
1472 | call = gimple_build_call_vec (node->decl, args_to_pass); |
1473 | gimple_set_block (g: call, DECL_INITIAL (current_function_decl)); |
1474 | args_to_pass.release (); |
1475 | |
1476 | /* For optimized away parameters, add on the caller side |
1477 | before the call |
1478 | DEBUG D#X => parm_Y(D) |
1479 | stmts and associate D#X with parm in decl_debug_args_lookup |
1480 | vector to say for debug info that if parameter parm had been passed, |
1481 | it would have value parm_Y(D). */ |
1482 | if (args_to_skip) |
1483 | { |
1484 | vec<tree, va_gc> **debug_args = NULL; |
1485 | unsigned i = 0, len = 0; |
1486 | if (MAY_HAVE_DEBUG_BIND_STMTS) |
1487 | { |
1488 | debug_args = decl_debug_args_lookup (node->decl); |
1489 | if (debug_args) |
1490 | len = vec_safe_length (v: *debug_args); |
1491 | } |
1492 | for (parm = DECL_ARGUMENTS (current_function_decl), num = 0; |
1493 | parm; parm = DECL_CHAIN (parm), num++) |
1494 | if (bitmap_bit_p (args_to_skip, num) && is_gimple_reg (parm)) |
1495 | { |
1496 | tree ddecl; |
1497 | gimple *def_temp; |
1498 | |
1499 | /* This needs to be done even without |
1500 | MAY_HAVE_DEBUG_BIND_STMTS, otherwise if it didn't exist |
1501 | before, we'd end up with different SSA_NAME_VERSIONs |
1502 | between -g and -g0. */ |
1503 | arg = get_or_create_ssa_default_def (cfun, parm); |
1504 | if (!MAY_HAVE_DEBUG_BIND_STMTS || debug_args == NULL) |
1505 | continue; |
1506 | |
1507 | while (i < len && (**debug_args)[i] != DECL_ORIGIN (parm)) |
1508 | i += 2; |
1509 | if (i >= len) |
1510 | continue; |
1511 | ddecl = (**debug_args)[i + 1]; |
1512 | def_temp |
1513 | = gimple_build_debug_bind (ddecl, unshare_expr (arg), call); |
1514 | gsi_insert_after (&gsi, def_temp, GSI_NEW_STMT); |
1515 | } |
1516 | BITMAP_FREE (args_to_skip); |
1517 | } |
1518 | |
1519 | /* We avoid address being taken on any variable used by split part, |
1520 | so return slot optimization is always possible. Moreover this is |
1521 | required to make DECL_BY_REFERENCE work. */ |
1522 | if (aggregate_value_p (DECL_RESULT (current_function_decl), |
1523 | TREE_TYPE (current_function_decl)) |
1524 | && (!is_gimple_reg_type (TREE_TYPE (DECL_RESULT (current_function_decl))) |
1525 | || DECL_BY_REFERENCE (DECL_RESULT (current_function_decl)))) |
1526 | gimple_call_set_return_slot_opt (s: call, return_slot_opt_p: true); |
1527 | |
1528 | if (add_tsan_func_exit) |
1529 | tsan_func_exit_call = gimple_build_call_internal (IFN_TSAN_FUNC_EXIT, 0); |
1530 | |
1531 | /* Update return value. This is bit tricky. When we do not return, |
1532 | do nothing. When we return we might need to update return_bb |
1533 | or produce a new return statement. */ |
1534 | if (!split_part_return_p) |
1535 | { |
1536 | gsi_insert_after (&gsi, call, GSI_NEW_STMT); |
1537 | if (tsan_func_exit_call) |
1538 | gsi_insert_after (&gsi, tsan_func_exit_call, GSI_NEW_STMT); |
1539 | } |
1540 | else |
1541 | { |
1542 | e = make_single_succ_edge (call_bb, return_bb, |
1543 | return_bb == EXIT_BLOCK_PTR_FOR_FN (cfun) |
1544 | ? 0 : EDGE_FALLTHRU); |
1545 | |
1546 | /* If there is return basic block, see what value we need to store |
1547 | return value into and put call just before it. */ |
1548 | if (return_bb != EXIT_BLOCK_PTR_FOR_FN (cfun)) |
1549 | { |
1550 | real_retval = retval; |
1551 | if (real_retval && split_point->split_part_set_retval) |
1552 | { |
1553 | gphi_iterator psi; |
1554 | |
1555 | /* See if we need new SSA_NAME for the result. |
1556 | When DECL_BY_REFERENCE is true, retval is actually pointer to |
1557 | return value and it is constant in whole function. */ |
1558 | if (TREE_CODE (retval) == SSA_NAME |
1559 | && !DECL_BY_REFERENCE (DECL_RESULT (current_function_decl))) |
1560 | { |
1561 | retval = copy_ssa_name (var: retval, stmt: call); |
1562 | |
1563 | /* See if there is PHI defining return value. */ |
1564 | for (psi = gsi_start_phis (return_bb); |
1565 | !gsi_end_p (i: psi); gsi_next (i: &psi)) |
1566 | if (!virtual_operand_p (op: gimple_phi_result (gs: psi.phi ()))) |
1567 | break; |
1568 | |
1569 | /* When there is PHI, just update its value. */ |
1570 | if (TREE_CODE (retval) == SSA_NAME |
1571 | && !gsi_end_p (i: psi)) |
1572 | add_phi_arg (psi.phi (), retval, e, UNKNOWN_LOCATION); |
1573 | /* Otherwise update the return BB itself. |
1574 | find_return_bb allows at most one assignment to return value, |
1575 | so update first statement. */ |
1576 | else |
1577 | { |
1578 | gimple_stmt_iterator bsi; |
1579 | for (bsi = gsi_start_bb (bb: return_bb); !gsi_end_p (i: bsi); |
1580 | gsi_next (i: &bsi)) |
1581 | if (greturn *return_stmt |
1582 | = dyn_cast <greturn *> (p: gsi_stmt (i: bsi))) |
1583 | { |
1584 | gimple_return_set_retval (gs: return_stmt, retval); |
1585 | break; |
1586 | } |
1587 | else if (gimple_code (g: gsi_stmt (i: bsi)) == GIMPLE_ASSIGN |
1588 | && !gimple_clobber_p (s: gsi_stmt (i: bsi))) |
1589 | { |
1590 | gimple_assign_set_rhs1 (gs: gsi_stmt (i: bsi), rhs: retval); |
1591 | break; |
1592 | } |
1593 | update_stmt (s: gsi_stmt (i: bsi)); |
1594 | /* Also adjust clobbers and debug stmts in return_bb. */ |
1595 | for (bsi = gsi_start_bb (bb: return_bb); !gsi_end_p (i: bsi); |
1596 | gsi_next (i: &bsi)) |
1597 | { |
1598 | gimple *stmt = gsi_stmt (i: bsi); |
1599 | if (gimple_clobber_p (s: stmt) |
1600 | || is_gimple_debug (gs: stmt)) |
1601 | { |
1602 | ssa_op_iter iter; |
1603 | use_operand_p use_p; |
1604 | bool update = false; |
1605 | FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, |
1606 | SSA_OP_USE) |
1607 | if (USE_FROM_PTR (use_p) == real_retval) |
1608 | { |
1609 | SET_USE (use_p, retval); |
1610 | update = true; |
1611 | } |
1612 | if (update) |
1613 | update_stmt (s: stmt); |
1614 | } |
1615 | } |
1616 | } |
1617 | } |
1618 | if (DECL_BY_REFERENCE (DECL_RESULT (current_function_decl))) |
1619 | { |
1620 | gimple_call_set_lhs (gs: call, build_simple_mem_ref (retval)); |
1621 | gsi_insert_after (&gsi, call, GSI_NEW_STMT); |
1622 | } |
1623 | else |
1624 | { |
1625 | tree restype; |
1626 | restype = TREE_TYPE (DECL_RESULT (current_function_decl)); |
1627 | gsi_insert_after (&gsi, call, GSI_NEW_STMT); |
1628 | if (!useless_type_conversion_p (TREE_TYPE (retval), restype)) |
1629 | { |
1630 | gimple *cpy; |
1631 | tree tem = create_tmp_reg (restype); |
1632 | tem = make_ssa_name (var: tem, stmt: call); |
1633 | cpy = gimple_build_assign (retval, NOP_EXPR, tem); |
1634 | gsi_insert_after (&gsi, cpy, GSI_NEW_STMT); |
1635 | retval = tem; |
1636 | } |
1637 | gimple_call_set_lhs (gs: call, lhs: retval); |
1638 | update_stmt (s: call); |
1639 | } |
1640 | } |
1641 | else |
1642 | gsi_insert_after (&gsi, call, GSI_NEW_STMT); |
1643 | if (tsan_func_exit_call) |
1644 | gsi_insert_after (&gsi, tsan_func_exit_call, GSI_NEW_STMT); |
1645 | } |
1646 | /* We don't use return block (there is either no return in function or |
1647 | multiple of them). So create new basic block with return statement. |
1648 | */ |
1649 | else |
1650 | { |
1651 | greturn *ret; |
1652 | if (split_point->split_part_set_retval |
1653 | && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (current_function_decl)))) |
1654 | { |
1655 | retval = DECL_RESULT (current_function_decl); |
1656 | |
1657 | /* We use temporary register to hold value when aggregate_value_p |
1658 | is false. Similarly for DECL_BY_REFERENCE we must avoid extra |
1659 | copy. */ |
1660 | if (!aggregate_value_p (retval, TREE_TYPE (current_function_decl)) |
1661 | && !DECL_BY_REFERENCE (retval)) |
1662 | retval = create_tmp_reg (TREE_TYPE (retval)); |
1663 | if (is_gimple_reg (retval)) |
1664 | { |
1665 | /* When returning by reference, there is only one SSA name |
1666 | assigned to RESULT_DECL (that is pointer to return value). |
1667 | Look it up or create new one if it is missing. */ |
1668 | if (DECL_BY_REFERENCE (retval)) |
1669 | retval = get_or_create_ssa_default_def (cfun, retval); |
1670 | /* Otherwise produce new SSA name for return value. */ |
1671 | else |
1672 | retval = make_ssa_name (var: retval, stmt: call); |
1673 | } |
1674 | if (DECL_BY_REFERENCE (DECL_RESULT (current_function_decl))) |
1675 | gimple_call_set_lhs (gs: call, build_simple_mem_ref (retval)); |
1676 | else |
1677 | gimple_call_set_lhs (gs: call, lhs: retval); |
1678 | gsi_insert_after (&gsi, call, GSI_NEW_STMT); |
1679 | } |
1680 | else |
1681 | { |
1682 | gsi_insert_after (&gsi, call, GSI_NEW_STMT); |
1683 | if (retval |
1684 | && is_gimple_reg_type (TREE_TYPE (retval)) |
1685 | && !is_gimple_val (retval)) |
1686 | { |
1687 | gassign *g |
1688 | = gimple_build_assign (make_ssa_name (TREE_TYPE (retval)), |
1689 | retval); |
1690 | retval = gimple_assign_lhs (gs: g); |
1691 | gsi_insert_after (&gsi, g, GSI_NEW_STMT); |
1692 | } |
1693 | } |
1694 | if (tsan_func_exit_call) |
1695 | gsi_insert_after (&gsi, tsan_func_exit_call, GSI_NEW_STMT); |
1696 | ret = gimple_build_return (retval); |
1697 | gsi_insert_after (&gsi, ret, GSI_NEW_STMT); |
1698 | } |
1699 | } |
1700 | free_dominance_info (CDI_DOMINATORS); |
1701 | free_dominance_info (CDI_POST_DOMINATORS); |
1702 | compute_fn_summary (node, true); |
1703 | } |
1704 | |
1705 | /* Execute function splitting pass. */ |
1706 | |
1707 | static unsigned int |
1708 | execute_split_functions (void) |
1709 | { |
1710 | gimple_stmt_iterator bsi; |
1711 | basic_block bb; |
1712 | sreal overall_time = 0; |
1713 | int overall_size = 0; |
1714 | int todo = 0; |
1715 | struct cgraph_node *node = cgraph_node::get (decl: current_function_decl); |
1716 | |
1717 | if (flags_from_decl_or_type (current_function_decl) |
1718 | & (ECF_NORETURN|ECF_MALLOC|ECF_RETURNS_TWICE)) |
1719 | { |
1720 | if (dump_file) |
1721 | fprintf (stream: dump_file, format: "Not splitting: noreturn/malloc/returns_twice " |
1722 | "function.\n" ); |
1723 | return 0; |
1724 | } |
1725 | if (MAIN_NAME_P (DECL_NAME (current_function_decl))) |
1726 | { |
1727 | if (dump_file) |
1728 | fprintf (stream: dump_file, format: "Not splitting: main function.\n" ); |
1729 | return 0; |
1730 | } |
1731 | if (node->frequency == NODE_FREQUENCY_UNLIKELY_EXECUTED) |
1732 | { |
1733 | if (dump_file) |
1734 | fprintf (stream: dump_file, format: "Not splitting: function is unlikely executed.\n" ); |
1735 | return 0; |
1736 | } |
1737 | /* This can be relaxed; function might become inlinable after splitting |
1738 | away the uninlinable part. */ |
1739 | if (ipa_fn_summaries |
1740 | && ipa_fn_summaries->get (node) |
1741 | && !ipa_fn_summaries->get (node)->inlinable) |
1742 | { |
1743 | if (dump_file) |
1744 | fprintf (stream: dump_file, format: "Not splitting: not inlinable.\n" ); |
1745 | return 0; |
1746 | } |
1747 | if (DECL_DISREGARD_INLINE_LIMITS (node->decl)) |
1748 | { |
1749 | if (dump_file) |
1750 | fprintf (stream: dump_file, format: "Not splitting: disregarding inline limits.\n" ); |
1751 | return 0; |
1752 | } |
1753 | /* This can be relaxed; most of versioning tests actually prevents |
1754 | a duplication. */ |
1755 | if (!tree_versionable_function_p (current_function_decl)) |
1756 | { |
1757 | if (dump_file) |
1758 | fprintf (stream: dump_file, format: "Not splitting: not versionable.\n" ); |
1759 | return 0; |
1760 | } |
1761 | /* FIXME: we could support this. */ |
1762 | if (DECL_STRUCT_FUNCTION (current_function_decl)->static_chain_decl) |
1763 | { |
1764 | if (dump_file) |
1765 | fprintf (stream: dump_file, format: "Not splitting: nested function.\n" ); |
1766 | return 0; |
1767 | } |
1768 | |
1769 | /* See if it makes sense to try to split. |
1770 | It makes sense to split if we inline, that is if we have direct calls to |
1771 | handle or direct calls are possibly going to appear as result of indirect |
1772 | inlining or LTO. Also handle -fprofile-generate as LTO to allow non-LTO |
1773 | training for LTO -fprofile-use build. |
1774 | |
1775 | Note that we are not completely conservative about disqualifying functions |
1776 | called once. It is possible that the caller is called more then once and |
1777 | then inlining would still benefit. */ |
1778 | if ((!node->callers |
1779 | /* Local functions called once will be completely inlined most of time. */ |
1780 | || (!node->callers->next_caller && node->local)) |
1781 | && !node->address_taken |
1782 | && !node->has_aliases_p () |
1783 | && (!flag_lto || !node->externally_visible)) |
1784 | { |
1785 | if (dump_file) |
1786 | fprintf (stream: dump_file, format: "Not splitting: not called directly " |
1787 | "or called once.\n" ); |
1788 | return 0; |
1789 | } |
1790 | |
1791 | /* FIXME: We can actually split if splitting reduces call overhead. */ |
1792 | if (!flag_inline_small_functions |
1793 | && !DECL_DECLARED_INLINE_P (current_function_decl)) |
1794 | { |
1795 | if (dump_file) |
1796 | fprintf (stream: dump_file, format: "Not splitting: not autoinlining and function" |
1797 | " is not inline.\n" ); |
1798 | return 0; |
1799 | } |
1800 | |
1801 | if (lookup_attribute (attr_name: "noinline" , DECL_ATTRIBUTES (current_function_decl))) |
1802 | { |
1803 | if (dump_file) |
1804 | fprintf (stream: dump_file, format: "Not splitting: function is noinline.\n" ); |
1805 | return 0; |
1806 | } |
1807 | if (lookup_attribute (attr_name: "section" , DECL_ATTRIBUTES (current_function_decl))) |
1808 | { |
1809 | if (dump_file) |
1810 | fprintf (stream: dump_file, format: "Not splitting: function is in user defined " |
1811 | "section.\n" ); |
1812 | return 0; |
1813 | } |
1814 | |
1815 | /* We enforce splitting after loop headers when profile info is not |
1816 | available. */ |
1817 | if (profile_status_for_fn (cfun) != PROFILE_READ) |
1818 | mark_dfs_back_edges (); |
1819 | |
1820 | /* Initialize bitmap to track forbidden calls. */ |
1821 | forbidden_dominators = BITMAP_ALLOC (NULL); |
1822 | calculate_dominance_info (CDI_DOMINATORS); |
1823 | |
1824 | /* Compute local info about basic blocks and determine function size/time. */ |
1825 | bb_info_vec.safe_grow_cleared (last_basic_block_for_fn (cfun) + 1, exact: true); |
1826 | best_split_point.split_bbs = NULL; |
1827 | basic_block return_bb = find_return_bb (); |
1828 | int tsan_exit_found = -1; |
1829 | FOR_EACH_BB_FN (bb, cfun) |
1830 | { |
1831 | sreal time = 0; |
1832 | int size = 0; |
1833 | sreal freq = bb->count.to_sreal_scale |
1834 | (ENTRY_BLOCK_PTR_FOR_FN (cfun)->count); |
1835 | |
1836 | if (dump_file && (dump_flags & TDF_DETAILS)) |
1837 | fprintf (stream: dump_file, format: "Basic block %i\n" , bb->index); |
1838 | |
1839 | for (bsi = gsi_start_bb (bb); !gsi_end_p (i: bsi); gsi_next (i: &bsi)) |
1840 | { |
1841 | sreal this_time; |
1842 | int this_size; |
1843 | gimple *stmt = gsi_stmt (i: bsi); |
1844 | |
1845 | this_size = estimate_num_insns (stmt, &eni_size_weights); |
1846 | this_time = (sreal)estimate_num_insns (stmt, &eni_time_weights) |
1847 | * freq; |
1848 | size += this_size; |
1849 | time += this_time; |
1850 | check_forbidden_calls (stmt); |
1851 | |
1852 | if (dump_file && (dump_flags & TDF_DETAILS)) |
1853 | { |
1854 | fprintf (stream: dump_file, format: " freq:%4.2f size:%3i time:%4.2f " , |
1855 | freq.to_double (), this_size, this_time.to_double ()); |
1856 | print_gimple_stmt (dump_file, stmt, 0); |
1857 | } |
1858 | |
1859 | if ((flag_sanitize & SANITIZE_THREAD) |
1860 | && gimple_call_internal_p (gs: stmt, fn: IFN_TSAN_FUNC_EXIT)) |
1861 | { |
1862 | /* We handle TSAN_FUNC_EXIT for splitting either in the |
1863 | return_bb, or in its immediate predecessors. */ |
1864 | if ((bb != return_bb && !find_edge (bb, return_bb)) |
1865 | || (tsan_exit_found != -1 |
1866 | && tsan_exit_found != (bb != return_bb))) |
1867 | { |
1868 | if (dump_file) |
1869 | fprintf (stream: dump_file, format: "Not splitting: TSAN_FUNC_EXIT" |
1870 | " in unexpected basic block.\n" ); |
1871 | BITMAP_FREE (forbidden_dominators); |
1872 | bb_info_vec.release (); |
1873 | return 0; |
1874 | } |
1875 | tsan_exit_found = bb != return_bb; |
1876 | } |
1877 | } |
1878 | overall_time += time; |
1879 | overall_size += size; |
1880 | bb_info_vec[bb->index].time = time; |
1881 | bb_info_vec[bb->index].size = size; |
1882 | } |
1883 | find_split_points (return_bb, overall_time, overall_size); |
1884 | if (best_split_point.split_bbs) |
1885 | { |
1886 | split_function (return_bb, split_point: &best_split_point, add_tsan_func_exit: tsan_exit_found == 1); |
1887 | BITMAP_FREE (best_split_point.ssa_names_to_pass); |
1888 | BITMAP_FREE (best_split_point.split_bbs); |
1889 | todo = TODO_update_ssa | TODO_cleanup_cfg; |
1890 | } |
1891 | BITMAP_FREE (forbidden_dominators); |
1892 | bb_info_vec.release (); |
1893 | return todo; |
1894 | } |
1895 | |
1896 | namespace { |
1897 | |
1898 | const pass_data pass_data_split_functions = |
1899 | { |
1900 | .type: GIMPLE_PASS, /* type */ |
1901 | .name: "fnsplit" , /* name */ |
1902 | .optinfo_flags: OPTGROUP_NONE, /* optinfo_flags */ |
1903 | .tv_id: TV_IPA_FNSPLIT, /* tv_id */ |
1904 | PROP_cfg, /* properties_required */ |
1905 | .properties_provided: 0, /* properties_provided */ |
1906 | .properties_destroyed: 0, /* properties_destroyed */ |
1907 | .todo_flags_start: 0, /* todo_flags_start */ |
1908 | .todo_flags_finish: 0, /* todo_flags_finish */ |
1909 | }; |
1910 | |
1911 | class pass_split_functions : public gimple_opt_pass |
1912 | { |
1913 | public: |
1914 | pass_split_functions (gcc::context *ctxt) |
1915 | : gimple_opt_pass (pass_data_split_functions, ctxt) |
1916 | {} |
1917 | |
1918 | /* opt_pass methods: */ |
1919 | bool gate (function *) final override; |
1920 | unsigned int execute (function *) final override |
1921 | { |
1922 | return execute_split_functions (); |
1923 | } |
1924 | |
1925 | }; // class pass_split_functions |
1926 | |
1927 | bool |
1928 | pass_split_functions::gate (function *) |
1929 | { |
1930 | /* When doing profile feedback, we want to execute the pass after profiling |
1931 | is read. So disable one in early optimization. */ |
1932 | return (flag_partial_inlining |
1933 | && !profile_arc_flag && !flag_branch_probabilities); |
1934 | } |
1935 | |
1936 | } // anon namespace |
1937 | |
1938 | gimple_opt_pass * |
1939 | make_pass_split_functions (gcc::context *ctxt) |
1940 | { |
1941 | return new pass_split_functions (ctxt); |
1942 | } |
1943 | |
1944 | /* Execute function splitting pass. */ |
1945 | |
1946 | static unsigned int |
1947 | execute_feedback_split_functions (void) |
1948 | { |
1949 | unsigned int retval = execute_split_functions (); |
1950 | if (retval) |
1951 | retval |= TODO_rebuild_cgraph_edges; |
1952 | return retval; |
1953 | } |
1954 | |
1955 | namespace { |
1956 | |
1957 | const pass_data pass_data_feedback_split_functions = |
1958 | { |
1959 | .type: GIMPLE_PASS, /* type */ |
1960 | .name: "feedback_fnsplit" , /* name */ |
1961 | .optinfo_flags: OPTGROUP_NONE, /* optinfo_flags */ |
1962 | .tv_id: TV_IPA_FNSPLIT, /* tv_id */ |
1963 | PROP_cfg, /* properties_required */ |
1964 | .properties_provided: 0, /* properties_provided */ |
1965 | .properties_destroyed: 0, /* properties_destroyed */ |
1966 | .todo_flags_start: 0, /* todo_flags_start */ |
1967 | .todo_flags_finish: 0, /* todo_flags_finish */ |
1968 | }; |
1969 | |
1970 | class pass_feedback_split_functions : public gimple_opt_pass |
1971 | { |
1972 | public: |
1973 | pass_feedback_split_functions (gcc::context *ctxt) |
1974 | : gimple_opt_pass (pass_data_feedback_split_functions, ctxt) |
1975 | {} |
1976 | |
1977 | /* opt_pass methods: */ |
1978 | bool gate (function *) final override; |
1979 | unsigned int execute (function *) final override |
1980 | { |
1981 | return execute_feedback_split_functions (); |
1982 | } |
1983 | |
1984 | }; // class pass_feedback_split_functions |
1985 | |
1986 | bool |
1987 | pass_feedback_split_functions::gate (function *) |
1988 | { |
1989 | /* We don't need to split when profiling at all, we are producing |
1990 | lousy code anyway. */ |
1991 | return (flag_partial_inlining |
1992 | && flag_branch_probabilities); |
1993 | } |
1994 | |
1995 | } // anon namespace |
1996 | |
1997 | gimple_opt_pass * |
1998 | make_pass_feedback_split_functions (gcc::context *ctxt) |
1999 | { |
2000 | return new pass_feedback_split_functions (ctxt); |
2001 | } |
2002 | |