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1 // Implementation of instruction-related RTL SSA functions -*- C++ -*-
2 // Copyright (C) 2020-2022 Free Software Foundation, Inc.
3 //
4 // This file is part of GCC.
5 //
6 // GCC is free software; you can redistribute it and/or modify it under
7 // the terms of the GNU General Public License as published by the Free
8 // Software Foundation; either version 3, or (at your option) any later
9 // version.
10 //
11 // GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 // WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 // FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 // for more details.
15 //
16 // You should have received a copy of the GNU General Public License
17 // along with GCC; see the file COPYING3. If not see
18 // <http://www.gnu.org/licenses/>.
19
20 #define INCLUDE_ALGORITHM
21 #define INCLUDE_FUNCTIONAL
22 #include "config.h"
23 #include "system.h"
24 #include "coretypes.h"
25 #include "backend.h"
26 #include "rtl.h"
27 #include "df.h"
28 #include "rtl-ssa.h"
29 #include "rtl-ssa/internals.h"
30 #include "rtl-ssa/internals.inl"
31 #include "predict.h"
32 #include "print-rtl.h"
33 #include "rtl-iter.h"
34
35 using namespace rtl_ssa;
36
37 // The gap to leave between program points when building up the list
38 // of instructions for the first time. Using 2 allows an instruction
39 // to be inserted between two others without resorting to splay tree
40 // ordering. Using 0 is useful as a debugging aid to stress the
41 // splay tree code.
42 static const unsigned int POINT_INCREASE = 2;
43
44 // Calculate and record the cost of the instruction, based on the
45 // form it had before any in-progress changes were made.
46 void
47 insn_info::calculate_cost () const
48 {
49 basic_block cfg_bb = BLOCK_FOR_INSN (m_rtl);
50 temporarily_undo_changes (0);
51 m_cost_or_uid = insn_cost (m_rtl, optimize_bb_for_speed_p (cfg_bb));
52 redo_changes (0);
53 }
54
55 // Add NOTE to the instruction's notes.
56 void
57 insn_info::add_note (insn_note *note)
58 {
59 insn_note **ptr = &m_first_note;
60 // Always put the order node first, since it's the one that's likely
61 // to be used most often.
62 if (*ptr && (*ptr)->kind () == insn_note_kind::ORDER_NODE)
63 ptr = &(*ptr)->m_next_note;
64 note->m_next_note = *ptr;
65 *ptr = note;
66 }
67
68 // Implement compare_with for the case in which this insn and OTHER
69 // have the same program point.
70 int
71 insn_info::slow_compare_with (const insn_info &other) const
72 {
73 return order_splay_tree::compare_nodes (get_known_order_node (),
74 other.get_known_order_node ());
75 }
76
77 // Print insn uid UID to PP, where UID has the same form as insn_info::uid.
78 void
79 insn_info::print_uid (pretty_printer *pp, int uid)
80 {
81 char tmp[3 * sizeof (uid) + 2];
82 if (uid < 0)
83 // An artificial instruction.
84 snprintf (tmp, sizeof (tmp), "a%d", -uid);
85 else
86 // A real RTL instruction.
87 snprintf (tmp, sizeof (tmp), "i%d", uid);
88 pp_string (pp, tmp);
89 }
90
91 // See comment above declaration.
92 void
93 insn_info::print_identifier (pretty_printer *pp) const
94 {
95 print_uid (pp, uid ());
96 }
97
98 // See comment above declaration.
99 void
100 insn_info::print_location (pretty_printer *pp) const
101 {
102 if (bb_info *bb = this->bb ())
103 {
104 ebb_info *ebb = bb->ebb ();
105 if (ebb && is_phi ())
106 ebb->print_identifier (pp);
107 else
108 bb->print_identifier (pp);
109 pp_string (pp, " at point ");
110 pp_decimal_int (pp, m_point);
111 }
112 else
113 pp_string (pp, "<unknown location>");
114 }
115
116 // See comment above declaration.
117 void
118 insn_info::print_identifier_and_location (pretty_printer *pp) const
119 {
120 if (m_is_asm)
121 pp_string (pp, "asm ");
122 if (m_is_debug_insn)
123 pp_string (pp, "debug ");
124 pp_string (pp, "insn ");
125 print_identifier (pp);
126 pp_string (pp, " in ");
127 print_location (pp);
128 }
129
130 // See comment above declaration.
131 void
132 insn_info::print_full (pretty_printer *pp) const
133 {
134 print_identifier_and_location (pp);
135 pp_colon (pp);
136 if (is_real ())
137 {
138 pp_newline_and_indent (pp, 2);
139 if (has_been_deleted ())
140 pp_string (pp, "deleted");
141 else
142 {
143 // Print the insn pattern to a temporary printer.
144 pretty_printer sub_pp;
145 print_insn_with_notes (&sub_pp, rtl ());
146 const char *text = pp_formatted_text (&sub_pp);
147
148 // Calculate the length of the maximum line in the pattern.
149 unsigned int max_len = 0;
150 const char *start = text;
151 while (const char *end = strchr (start, '\n'))
152 {
153 max_len = MAX (max_len, (unsigned int) (end - start));
154 start = end + 1;
155 }
156
157 // Print a separator before or after the pattern.
158 auto print_top_bottom = [&]()
159 {
160 pp_character (pp, '+');
161 for (unsigned int i = 0; i < max_len + 2; ++i)
162 pp_character (pp, '-');
163 };
164
165 print_top_bottom ();
166 start = text;
167 while (const char *end = strchr (start, '\n'))
168 {
169 pp_newline_and_indent (pp, 0);
170 pp_character (pp, '|');
171 // Each line of the pattern already starts with a space.
172 // so we don't need to add another one here.
173 pp_append_text (pp, start, end);
174 start = end + 1;
175 }
176 pp_newline_and_indent (pp, 0);
177 print_top_bottom ();
178
179 if (m_cost_or_uid != UNKNOWN_COST)
180 {
181 pp_newline_and_indent (pp, 0);
182 pp_string (pp, "cost: ");
183 pp_decimal_int (pp, m_cost_or_uid);
184 }
185 if (m_has_pre_post_modify)
186 {
187 pp_newline_and_indent (pp, 0);
188 pp_string (pp, "has pre/post-modify operations");
189 }
190 if (m_has_volatile_refs)
191 {
192 pp_newline_and_indent (pp, 0);
193 pp_string (pp, "has volatile refs");
194 }
195 }
196 pp_indentation (pp) -= 2;
197 }
198
199 auto print_accesses = [&](const char *heading, access_array accesses,
200 unsigned int flags)
201 {
202 if (!accesses.empty ())
203 {
204 pp_newline_and_indent (pp, 2);
205 pp_string (pp, heading);
206 pp_newline_and_indent (pp, 2);
207 pp_accesses (pp, accesses, flags);
208 pp_indentation (pp) -= 4;
209 }
210 };
211
212 print_accesses ("uses:", uses (), PP_ACCESS_USER);
213 auto *call_clobbers_note = find_note<insn_call_clobbers_note> ();
214 if (call_clobbers_note)
215 {
216 pp_newline_and_indent (pp, 2);
217 pp_string (pp, "has call clobbers for ABI ");
218 pp_decimal_int (pp, call_clobbers_note->abi_id ());
219 pp_indentation (pp) -= 2;
220 }
221 print_accesses ("defines:", defs (), PP_ACCESS_SETTER);
222 if (num_uses () == 0 && !call_clobbers_note && num_defs () == 0)
223 {
224 pp_newline_and_indent (pp, 2);
225 pp_string (pp, "has no uses or defs");
226 pp_indentation (pp) -= 2;
227 }
228
229 if (order_node *node = get_order_node ())
230 {
231 while (node->m_parent)
232 node = node->m_parent;
233
234 pp_newline_and_indent (pp, 2);
235 pp_string (pp, "insn order: ");
236 pp_newline_and_indent (pp, 2);
237 auto print_order = [](pretty_printer *pp, order_node *node)
238 {
239 print_uid (pp, node->uid ());
240 };
241 order_splay_tree::print (pp, node, print_order);
242 pp_indentation (pp) -= 4;
243 }
244 }
245
246 // Return an insn_info::order_node for INSN, creating one if necessary.
247 insn_info::order_node *
248 function_info::need_order_node (insn_info *insn)
249 {
250 insn_info::order_node *order = insn->get_order_node ();
251 if (!order)
252 {
253 order = allocate<insn_info::order_node> (insn->uid ());
254 insn->add_note (order);
255 }
256 return order;
257 }
258
259 // Add instruction INSN immediately after AFTER in the reverse postorder list.
260 // INSN is not currently in the list.
261 void
262 function_info::add_insn_after (insn_info *insn, insn_info *after)
263 {
264 gcc_checking_assert (!insn->has_insn_links ());
265
266 insn->copy_next_from (after);
267 after->set_next_any_insn (insn);
268
269 // The prev link is easy if AFTER and INSN are the same type.
270 // Handle the other cases below.
271 if (after->is_debug_insn () == insn->is_debug_insn ())
272 insn->set_prev_sametype_insn (after);
273
274 if (insn_info *next = insn->next_any_insn ())
275 {
276 if (insn->is_debug_insn () == next->is_debug_insn ())
277 {
278 // INSN might now be the start of the subsequence of debug insns,
279 // and so its prev pointer might point to the end of the subsequence
280 // instead of AFTER.
281 insn->copy_prev_from (next);
282 next->set_prev_sametype_insn (insn);
283 }
284 else if (insn->is_debug_insn ()) // && !next->is_debug_insn ()
285 {
286 // INSN ends a subsequence of debug instructions. Find the
287 // first debug instruction in the subsequence, which might
288 // be INSN itself. (If it isn't, then AFTER is also a debug
289 // instruction and we updated INSN's prev link above.)
290 insn_info *first = next->prev_nondebug_insn ()->next_any_insn ();
291 first->set_last_debug_insn (insn);
292 }
293 else // !insn->is_debug_insn () && next->is_debug_insn ()
294 // At present we don't (need to) support inserting a nondebug
295 // instruction between two existing debug instructions.
296 gcc_assert (!after->is_debug_insn ());
297
298 // If AFTER and NEXT are separated by at least two points, we can
299 // use a unique point number for INSN. Otherwise INSN will have
300 // the same point number as AFTER.
301 insn->set_point ((next->point () + after->point ()) / 2);
302 }
303 else
304 {
305 if (!insn->is_debug_insn ())
306 {
307 insn->set_prev_sametype_insn (m_last_nondebug_insn);
308 m_last_nondebug_insn = insn;
309 }
310 else
311 // There is now at least one debug instruction after
312 // m_last_nondebug_insn: either INSN itself, or the start of
313 // a longer subsequence of debug insns that now ends with AFTER
314 // followed by INSN.
315 m_last_nondebug_insn->next_any_insn ()->set_last_debug_insn (insn);
316 m_last_insn = insn;
317
318 insn->set_point (after->point () + POINT_INCREASE);
319 }
320
321 // If INSN's program point is the same as AFTER's, we need to use the
322 // splay tree to record their relative order.
323 if (insn->point () == after->point ())
324 {
325 insn_info::order_node *after_node = need_order_node (after);
326 insn_info::order_node *insn_node = need_order_node (insn);
327 insn_info::order_splay_tree::insert_child (after_node, 1, insn_node);
328 }
329 }
330
331 // Remove INSN from the function's list of instructions.
332 void
333 function_info::remove_insn (insn_info *insn)
334 {
335 if (insn_info::order_node *order = insn->get_order_node ())
336 insn_info::order_splay_tree::remove_node (order);
337
338 if (auto *note = insn->find_note<insn_call_clobbers_note> ())
339 {
340 ebb_call_clobbers_info *ecc = insn->ebb ()->first_call_clobbers ();
341 while (ecc->abi ()->id () != note->abi_id ())
342 ecc = ecc->next ();
343 int comparison = lookup_call_clobbers (*ecc, insn);
344 gcc_assert (comparison == 0);
345 ecc->remove_root ();
346 }
347
348 insn_info *prev = insn->prev_any_insn ();
349 insn_info *next = insn->next_any_insn ();
350 insn_info *prev_nondebug = insn->prev_nondebug_insn ();
351 insn_info *next_nondebug = insn->next_nondebug_insn ();
352
353 // We should never remove the entry or exit block's instructions.
354 // At present we also don't remove entire blocks, so should never
355 // remove debug instructions.
356 gcc_checking_assert (prev_nondebug
357 && next_nondebug
358 && !insn->is_debug_insn ());
359
360 if (prev->is_debug_insn () && next->is_debug_insn ())
361 {
362 // We need to stitch together two subsequences of debug insns.
363 insn_info *last = next->last_debug_insn ();
364 next->set_prev_sametype_insn (prev);
365 prev_nondebug->next_any_insn ()->set_last_debug_insn (last);
366 }
367 prev->set_next_any_insn (next);
368 next_nondebug->set_prev_sametype_insn (prev_nondebug);
369
370 insn->clear_insn_links ();
371 }
372
373 // Create an artificial instruction for BB, associating it with RTL (which can
374 // be null). Add the new instruction to the end of the function's list and
375 // return the new instruction.
376 insn_info *
377 function_info::append_artificial_insn (bb_info *bb, rtx_insn *rtl)
378 {
379 insn_info *insn = allocate<insn_info> (bb, rtl, m_next_artificial_uid);
380 m_next_artificial_uid -= 1;
381 append_insn (insn);
382 return insn;
383 }
384
385 // Finish building a new list of uses and definitions for instruction INSN.
386 void
387 function_info::finish_insn_accesses (insn_info *insn)
388 {
389 unsigned int num_defs = m_temp_defs.length ();
390 unsigned int num_uses = m_temp_uses.length ();
391 obstack_make_room (&m_obstack, num_defs + num_uses);
392 if (num_defs)
393 {
394 sort_accesses (m_temp_defs);
395 obstack_grow (&m_obstack, m_temp_defs.address (),
396 num_defs * sizeof (access_info *));
397 m_temp_defs.truncate (0);
398 }
399 if (num_uses)
400 {
401 sort_accesses (m_temp_uses);
402 obstack_grow (&m_obstack, m_temp_uses.address (),
403 num_uses * sizeof (access_info *));
404 m_temp_uses.truncate (0);
405 }
406 void *addr = obstack_finish (&m_obstack);
407 insn->set_accesses (static_cast<access_info **> (addr), num_defs, num_uses);
408 }
409
410 // Called while building SSA form using BI. Create and return a use of
411 // register RESOURCE in INSN. Create a degenerate phi where necessary.
412 use_info *
413 function_info::create_reg_use (build_info &bi, insn_info *insn,
414 resource_info resource)
415 {
416 set_info *value = bi.current_reg_value (resource.regno);
417 if (value && value->ebb () != bi.current_ebb)
418 {
419 if (insn->is_debug_insn ())
420 value = look_through_degenerate_phi (value);
421 else if (bitmap_bit_p (bi.potential_phi_regs, resource.regno))
422 {
423 // VALUE is defined by a previous EBB and RESOURCE has multiple
424 // definitions. Create a degenerate phi in the current EBB
425 // so that all definitions and uses follow a linear RPO view;
426 // see rtl.texi for details.
427 access_info *inputs[] = { look_through_degenerate_phi (value) };
428 value = create_phi (bi.current_ebb, value->resource (), inputs, 1);
429 bi.record_reg_def (value);
430 }
431 }
432 auto *use = allocate<use_info> (insn, resource, value);
433 add_use (use);
434 return use;
435 }
436
437 // Called while building SSA form using BI. Record that INSN contains
438 // read reference REF. If this requires new entries to be added to
439 // INSN->uses (), add those entries to the list we're building in
440 // m_temp_uses.
441 void
442 function_info::record_use (build_info &bi, insn_info *insn,
443 rtx_obj_reference ref)
444 {
445 unsigned int regno = ref.regno;
446 machine_mode mode = ref.is_reg () ? ref.mode : BLKmode;
447 access_info *access = bi.last_access[ref.regno + 1];
448 use_info *use = safe_dyn_cast<use_info *> (access);
449 if (!use)
450 {
451 set_info *value = safe_dyn_cast<set_info *> (access);
452 // In order to ensure that -g doesn't affect codegen, uses in debug
453 // instructions do not affect liveness, either in DF or here.
454 // This means that there might be no correct definition of the resource
455 // available (e.g. if it would require a phi node that the nondebug
456 // code doesn't need). Perhaps we could have "debug phi nodes" as
457 // well as "debug instructions", but that would require a method
458 // of building phi nodes that didn't depend on DF liveness information,
459 // and so might be significantly more expensive.
460 //
461 // Therefore, the only value we try to attach to a use by a debug
462 // instruction is VALUE itself (as we would for nondebug instructions).
463 // We then need to make a conservative check for whether VALUE is
464 // actually correct.
465 auto value_is_valid = [&]()
466 {
467 // Memmory always has a valid definition.
468 if (ref.is_mem ())
469 return true;
470
471 // If VALUE would lead to an uninitialized use anyway, there's
472 // nothing to check.
473 if (!value)
474 return false;
475
476 // If the previous definition occurs in the same EBB then it
477 // is certainly correct.
478 if (value->ebb () == bi.current_ebb)
479 return true;
480
481 // Check if VALUE is the function's only definition of REGNO.
482 // (We already know that it dominates the use.)
483 if (!bitmap_bit_p (bi.potential_phi_regs, regno))
484 return true;
485
486 // If the register is live on entry to the EBB but not used
487 // within it, VALUE is the correct live-in value.
488 if (!bi.ebb_live_in_for_debug)
489 calculate_ebb_live_in_for_debug (bi);
490 if (bitmap_bit_p (bi.ebb_live_in_for_debug, regno))
491 return true;
492
493 // Punt for other cases.
494 return false;
495 };
496 if (insn->is_debug_insn () && !value_is_valid ())
497 value = nullptr;
498
499 use = create_reg_use (bi, insn, { mode, regno });
500 m_temp_uses.safe_push (use);
501 bi.last_access[ref.regno + 1] = use;
502 use->record_reference (ref, true);
503 }
504 else
505 {
506 // Record the mode of the largest use. The choice is arbitrary if
507 // the instruction (unusually) references the same register in two
508 // different but equal-sized modes.
509 gcc_checking_assert (use->insn () == insn);
510 if (HARD_REGISTER_NUM_P (regno)
511 && partial_subreg_p (use->mode (), mode))
512 use->set_mode (mode);
513 use->record_reference (ref, false);
514 }
515 }
516
517 // Called while building SSA form for INSN using BI. Record the effect
518 // of call clobbers in RTL. We have already added the explicit sets and
519 // clobbers for RTL, which have priority over any call clobbers.
520 void
521 function_info::record_call_clobbers (build_info &bi, insn_info *insn,
522 rtx_call_insn *rtl)
523 {
524 // See whether we should record this call in the EBB's list of
525 // call clobbers. Three things affect this choice:
526 //
527 // (1) The list is the only way we have of recording partial clobbers.
528 // All calls that only partially clobber registers must therefore
529 // be in the list.
530 //
531 // (2) Adding calls to the list is much more memory-efficient than
532 // creating a long list of clobber_infos.
533 //
534 // (3) Adding calls to the list limits the ability to move definitions
535 // of registers that are normally fully or partially clobbered
536 // by the associated predefined ABI. So adding calls to the list
537 // can hamper optimization if (thanks to -fipa-ra) the number of
538 // clobbers is much smaller than the usual set.
539 //
540 // The trade-off that we currently take is to use the list if there
541 // are some registers that the call only partially clobbers or if
542 // the set of clobbers is the standard set.
543 function_abi abi = insn_callee_abi (rtl);
544 if (abi.base_abi ().full_reg_clobbers () == abi.full_reg_clobbers ()
545 || abi.full_and_partial_reg_clobbers () != abi.full_reg_clobbers ())
546 {
547 // Find an entry for this predefined ABI, creating one if necessary.
548 ebb_call_clobbers_info *ecc = bi.current_ebb->first_call_clobbers ();
549 while (ecc && ecc->abi () != &abi.base_abi ())
550 ecc = ecc->next ();
551 if (!ecc)
552 {
553 ecc = allocate<ebb_call_clobbers_info> (&abi.base_abi ());
554 ecc->m_next = bi.current_ebb->first_call_clobbers ();
555 bi.current_ebb->set_first_call_clobbers (ecc);
556 }
557
558 auto abi_id = abi.base_abi ().id ();
559 auto *insn_clobbers = allocate<insn_call_clobbers_note> (abi_id, insn);
560 insn->add_note (insn_clobbers);
561
562 ecc->insert_max_node (insn_clobbers);
563 }
564 else
565 for (unsigned int regno = 0; regno < FIRST_PSEUDO_REGISTER; ++regno)
566 if (TEST_HARD_REG_BIT (abi.full_reg_clobbers (), regno))
567 {
568 def_info *def = m_defs[regno + 1];
569 if (!def || def->last_def ()->insn () != insn)
570 {
571 def = allocate<clobber_info> (insn, regno);
572 def->m_is_call_clobber = true;
573 append_def (def);
574 m_temp_defs.safe_push (def);
575 bi.record_reg_def (def);
576 }
577 }
578 }
579
580 // Called while building SSA form using BI. Record that INSN contains
581 // write reference REF. Add associated def_infos to the list of accesses
582 // that we're building in m_temp_defs. Record the register's new live
583 // value in BI.
584 void
585 function_info::record_def (build_info &bi, insn_info *insn,
586 rtx_obj_reference ref)
587 {
588 // Punt if we see multiple definitions of the same resource.
589 // This can happen for several reasons:
590 //
591 // - An instruction might store two values to memory at once, giving two
592 // distinct memory references.
593 //
594 // - An instruction might assign to multiple pieces of a wide pseudo
595 // register. For example, on 32-bit targets, an instruction might
596 // assign to both the upper and lower halves of a 64-bit pseudo register.
597 //
598 // - It's possible for the same register to be clobbered by the
599 // CALL_INSN_FUNCTION_USAGE and to be set by the main instruction
600 // pattern as well. In that case, the clobber conceptually happens
601 // before the set and can essentially be ignored.
602 //
603 // - Similarly, global registers are implicitly set by a call but can
604 // be explicitly set or clobbered as well. In that situation, the sets
605 // are listed first and should win over a clobber.
606 unsigned int regno = ref.regno;
607 machine_mode mode = ref.is_reg () ? ref.mode : BLKmode;
608 def_info *def = safe_dyn_cast<def_info *> (bi.last_access[ref.regno + 1]);
609 if (def && def->insn () == insn)
610 {
611 if (!ref.is_clobber ())
612 {
613 gcc_checking_assert (!is_a<clobber_info *> (def));
614 def->record_reference (ref, false);
615 }
616 return;
617 }
618
619 // Memory is always well-defined, so only use clobber_infos for registers.
620 if (ref.is_reg () && ref.is_clobber ())
621 def = allocate<clobber_info> (insn, regno);
622 else
623 def = allocate<set_info> (insn, resource_info { mode, regno });
624 def->record_reference (ref, true);
625 append_def (def);
626 m_temp_defs.safe_push (def);
627 bi.record_reg_def (def);
628 }
629
630 // Called while building SSA form using BI. Add an insn_info for RTL
631 // to the block that we're current building.
632 void
633 function_info::add_insn_to_block (build_info &bi, rtx_insn *rtl)
634 {
635 insn_info *insn = allocate<insn_info> (bi.current_bb, rtl, UNKNOWN_COST);
636 append_insn (insn);
637
638 vec_rtx_properties properties;
639 properties.add_insn (rtl, true);
640 insn->set_properties (properties);
641
642 start_insn_accesses ();
643
644 // Record the uses.
645 for (rtx_obj_reference ref : properties.refs ())
646 if (ref.is_read ())
647 record_use (bi, insn, ref);
648
649 // Restore the contents of bi.last_access, which we used as a cache
650 // when assembling the uses.
651 for (access_info *access : m_temp_uses)
652 {
653 unsigned int regno = access->regno ();
654 gcc_checking_assert (bi.last_access[regno + 1] == access);
655 bi.last_access[regno + 1] = as_a<use_info *> (access)->def ();
656 }
657
658 // Record the definitions.
659 for (rtx_obj_reference ref : properties.refs ())
660 if (ref.is_write ())
661 record_def (bi, insn, ref);
662
663 // Logically these happen before the explicit definitions, but if the
664 // explicit definitions and call clobbers reference the same register,
665 // the explicit definition should win.
666 if (auto *call_rtl = dyn_cast<rtx_call_insn *> (rtl))
667 record_call_clobbers (bi, insn, call_rtl);
668
669 finish_insn_accesses (insn);
670 }
671
672 // Check whether INSN sets any registers that are never subsequently used.
673 // If so, add REG_UNUSED notes for them. The caller has already removed
674 // any previous REG_UNUSED notes.
675 void
676 function_info::add_reg_unused_notes (insn_info *insn)
677 {
678 rtx_insn *rtl = insn->rtl ();
679
680 auto handle_potential_set = [&](rtx pattern)
681 {
682 if (GET_CODE (pattern) != SET)
683 return;
684
685 rtx dest = SET_DEST (pattern);
686 if (!REG_P (dest))
687 return;
688
689 def_array defs = insn->defs ();
690 unsigned int index = find_access_index (defs, REGNO (dest));
691 for (unsigned int i = 0; i < REG_NREGS (dest); ++i)
692 {
693 def_info *def = defs[index + i];
694 gcc_checking_assert (def->regno () == REGNO (dest) + i);
695 set_info *set = dyn_cast<set_info *> (def);
696 if (set && set->has_nondebug_uses ())
697 return;
698 }
699 add_reg_note (rtl, REG_UNUSED, dest);
700 };
701
702 rtx pattern = PATTERN (rtl);
703 if (GET_CODE (pattern) == PARALLEL)
704 for (int i = 0; i < XVECLEN (pattern, 0); ++i)
705 handle_potential_set (XVECEXP (pattern, 0, i));
706 else
707 handle_potential_set (pattern);
708 }
709
710 // Search TREE for call clobbers at INSN. Return:
711 //
712 // - less than zero if INSN occurs before the root of TREE
713 // - 0 if INSN is the root of TREE
714 // - greater than zero if INSN occurs after the root of TREE
715 int
716 rtl_ssa::lookup_call_clobbers (insn_call_clobbers_tree &tree, insn_info *insn)
717 {
718 auto compare = [&](insn_call_clobbers_note *clobbers)
719 {
720 return insn->compare_with (clobbers->insn ());
721 };
722 return tree.lookup (compare);
723 }
724
725 // Print a description of INSN to PP.
726 void
727 rtl_ssa::pp_insn (pretty_printer *pp, const insn_info *insn)
728 {
729 if (!insn)
730 pp_string (pp, "<null>");
731 else
732 insn->print_full (pp);
733 }
734
735 // Print a description of INSN to FILE.
736 void
737 dump (FILE *file, const insn_info *insn)
738 {
739 dump_using (file, pp_insn, insn);
740 }
741
742 // Debug interface to the dump routine above.
743 void debug (const insn_info *x) { dump (stderr, x); }