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1 : // Access-related classes for RTL SSA -*- C++ -*-
2 : // Copyright (C) 2020-2026 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 : namespace rtl_ssa {
21 :
22 : // Forward declarations.
23 : class bb_info;
24 : class clobber_group;
25 : class def_node;
26 : class ebb_info;
27 : class insn_info;
28 : class phi_info;
29 : class set_info;
30 :
31 : // Used as a boolean argunent to certain routines.
32 : enum class ignore_clobbers { NO, YES };
33 :
34 : // Represents something that the SSA form tracks: either a register
35 : // or memory.
36 : class resource_info
37 : {
38 : public:
39 : // Return true if this resource represents memory.
40 0 : bool is_mem () const { return regno == MEM_REGNO; }
41 :
42 : // Return true if this resource represents a register.
43 : bool is_reg () const { return regno != MEM_REGNO; }
44 :
45 : // Print the name of the resource to PP.
46 : void print_identifier (pretty_printer *pp) const;
47 :
48 : // Possibly print additional information about the resource to PP.
49 : void print_context (pretty_printer *pp) const;
50 :
51 : // A combination of print_identifier and print_context.
52 : void print (pretty_printer *pp) const;
53 :
54 : // The mode with which the resource is being defined or used. This is
55 : // always BLKmode for memory. It can also be BLKmode for registers if
56 : // we don't yet know the real mode, or if the mode is not relevant for
57 : // some reason.
58 : machine_mode mode;
59 :
60 : // The pseudo register or single hard register that the resource represents,
61 : // or MEM_REGNO for memory.
62 : unsigned int regno;
63 : };
64 :
65 : // For simplicity, we treat memory as a single unified entity.
66 : const resource_info memory = { E_BLKmode, MEM_REGNO };
67 :
68 : // Flags used when printing access_infos.
69 : //
70 : // Print the location at which the access occurs. This is redundant
71 : // when the access is being printed as part of the instruction or phi node
72 : // that contains the access.
73 : const unsigned int PP_ACCESS_INCLUDE_LOCATION = 1U << 0;
74 : //
75 : // Print links to other accesses: the definition that defines a use,
76 : // the uses of a definition, and the inputs of a phi node.
77 : const unsigned int PP_ACCESS_INCLUDE_LINKS = 1U << 1;
78 : //
79 : // Print additional properties about the access.
80 : const unsigned int PP_ACCESS_INCLUDE_PROPERTIES = 1U << 2;
81 : //
82 : // The usual flags when printing an access in isolation.
83 : const unsigned int PP_ACCESS_DEFAULT = (PP_ACCESS_INCLUDE_LOCATION
84 : | PP_ACCESS_INCLUDE_LINKS
85 : | PP_ACCESS_INCLUDE_PROPERTIES);
86 : //
87 : // The usual flags when printing a def_info from its defining instruction.
88 : const unsigned int PP_ACCESS_SETTER = (PP_ACCESS_INCLUDE_LINKS
89 : | PP_ACCESS_INCLUDE_PROPERTIES);
90 : //
91 : // The usual flags when printing a use_info from its user.
92 : const unsigned int PP_ACCESS_USER = PP_ACCESS_INCLUDE_PROPERTIES;
93 :
94 : // The various ways of accessing a resource. The two range checks that
95 : // we need to perform are [SET, PHI] (for set_info) and [SET, CLOBBER]
96 : // (for def_info), so the ordering tries to make those tests as
97 : // efficient as possible.
98 : enum class access_kind : uint8_t
99 : {
100 : // Set the resource to a useful value.
101 : SET,
102 :
103 : // A form of SET that collects the possible incoming values of the
104 : // resource using a phi node; the resource does not actually change value.
105 : PHI,
106 :
107 : // Set the resource to a value that is both unknown and not useful.
108 : CLOBBER,
109 :
110 : // Use the current value of the resource.
111 : USE
112 : };
113 :
114 : // A base class that represents an access to a resource.
115 : class access_info
116 : {
117 : // Size: 1 LP64 word
118 : friend class function_info;
119 :
120 : public:
121 : // Return the resource that is being accessed.
122 171645121 : resource_info resource () const { return { m_mode, m_regno }; }
123 :
124 : // Return true if the access is to memory.
125 345650491 : bool is_mem () const { return m_regno == MEM_REGNO; }
126 :
127 : // Return true if the access is to a register.
128 134187584 : bool is_reg () const { return m_regno != MEM_REGNO; }
129 :
130 : // If the access is to a register, return the register number,
131 : // otherwise return MEM_REGNO.
132 4191969885 : unsigned int regno () const { return m_regno; }
133 :
134 : // For sets, return the mode of the value to which the resource is being set.
135 : // For uses, return the mode in which the resource is being used (which for
136 : // hard registers might be different from the mode in which the resource
137 : // was set).
138 : //
139 : // When accessing memory, the mode is always BLKmode. When accessing
140 : // pseudo registers, the mode is always the mode of the pseudo register
141 : // (and so doesn't, for example, take subregs into account).
142 539855436 : machine_mode mode () const { return m_mode; }
143 :
144 : // Return the kind of access that this is.
145 6139492037 : access_kind kind () const { return m_kind; }
146 :
147 : // Return true if the access occurs in a phi node or an "artificial"
148 : // instruction (see insn_info), false if it occurs in a real instruction.
149 53219224 : bool is_artificial () const { return m_is_artificial; }
150 :
151 : // Return the opposite of is_artificial.
152 : bool is_real () const { return !m_is_artificial; }
153 :
154 : // Return true if this access is a set_info whose result is used by at least
155 : // one nondebug instruction.
156 : bool is_set_with_nondebug_insn_uses () const;
157 :
158 : // Return true if the access describes a set_info and if the value
159 : // is defined by an RTX_AUTOINC rtx.
160 : bool is_pre_post_modify () const { return m_is_pre_post_modify; }
161 :
162 : // Return true if the access is a clobber_info that describes the effect
163 : // of a called function. This kind of clobber is added for -fipa-ra
164 : // functions that clobber only a strict subset of the normal ABI set.
165 1016761 : bool is_call_clobber () const { return m_is_call_clobber; }
166 :
167 : // Return true if the access is a use_info that simply marks a point in
168 : // the live range of a set_info at which the value is live out from
169 : // the containing EBB.
170 174245370 : bool is_live_out_use () const { return m_is_live_out_use; }
171 :
172 : // Return true if the access is a use_info for an instruction and if
173 : // at least some of the uses occur within a MEM address.
174 : //
175 : // There shouldn't be a need to check whether *all* uses occur within
176 : // a MEM address, since in principle:
177 : //
178 : // A: (set (reg:SI R1) (mem:SI (post_inc:SI (reg:SI R2))))
179 : //
180 : // should be semantically equivalent to:
181 : //
182 : // B: (parallel [(set (reg:SI R1) (mem:SI (reg:SI R2)))
183 : // (set (reg:SI R2) (plus:SI (reg:SI R2) (const_int 4)))])
184 : //
185 : // even though R2 occurs only in MEMs for A but occurs outside MEMs for B.
186 165898754 : bool includes_address_uses () const { return m_includes_address_uses; }
187 :
188 : // Return true if the access occurs in an instruction and if at least
189 : // some accesses to resource () occur in a read-modify-write context.
190 : // This is equivalent to the DF_REF_READ_WRITE flag.
191 161328749 : bool includes_read_writes () const { return m_includes_read_writes; }
192 :
193 : // Return true if the access occurs in an instruction and if at least
194 : // some accesses to resource () occur in a subreg context.
195 53755129 : bool includes_subregs () const { return m_includes_subregs; }
196 :
197 : // Return true if the access occurs in an instruction and if at least
198 : // some accesses to resource () occur in a multi-register REG.
199 : // This implies that resource () is a hard register.
200 154263868 : bool includes_multiregs () const { return m_includes_multiregs; }
201 :
202 : // Return true if the access occurs in a real nondebug instruction
203 : // and if all accesses to resource () occur in notes, rather than
204 : // in the main instruction pattern.
205 172903855 : bool only_occurs_in_notes () const { return m_only_occurs_in_notes; }
206 :
207 : // Return true if this is a temporary access, e.g. one created for
208 : // an insn that is about to be inserted.
209 92366253 : bool is_temporary () const { return m_is_temp; }
210 :
211 : protected:
212 : access_info (resource_info, access_kind);
213 :
214 : void print_prefix_flags (pretty_printer *) const;
215 : void print_properties_on_new_lines (pretty_printer *) const;
216 :
217 : private:
218 155631509 : void set_mode (machine_mode mode) { m_mode = mode; }
219 :
220 : // The values returned by the accessors above.
221 : unsigned int m_regno;
222 : machine_mode m_mode : MACHINE_MODE_BITSIZE;
223 : access_kind m_kind : 2;
224 :
225 : protected:
226 : // The value returned by the accessors above.
227 : unsigned int m_is_artificial : 1;
228 : unsigned int m_is_set_with_nondebug_insn_uses : 1;
229 : unsigned int m_is_pre_post_modify : 1;
230 : unsigned int m_is_call_clobber : 1;
231 : unsigned int m_is_live_out_use : 1;
232 : unsigned int m_includes_address_uses : 1;
233 : unsigned int m_includes_read_writes : 1;
234 : unsigned int m_includes_subregs : 1;
235 : unsigned int m_includes_multiregs : 1;
236 : unsigned int m_only_occurs_in_notes : 1;
237 :
238 : // True if this access is a use_insn that occurs in a nondebug instruction,
239 : // and if there are no following uses by nondebug instructions. The next use
240 : // is null, a use_info for a debug instruction, or a use_info for a phi node.
241 : //
242 : // Providing this helps to optimize use_info::next_nondebug_insn_use.
243 : unsigned int m_is_last_nondebug_insn_use : 1;
244 :
245 : // True if this access is a use_info for a debug instruction or
246 : // a phi node.
247 : unsigned int m_is_in_debug_insn_or_phi : 1;
248 :
249 : private:
250 : // Used as a flag during various update routines; has no long-lasting
251 : // meaning.
252 : unsigned int m_has_been_superceded : 1;
253 :
254 : // Indicates that this access has been allocated on the function_info's
255 : // temporary obstack and so is not (yet) part of the proper SSA form.
256 : unsigned int m_is_temp : 1;
257 : };
258 :
259 : // A contiguous array of access_info pointers. Used to represent a
260 : // (mostly small) number of definitions and/or uses.
261 : using access_array = array_slice<access_info *const>;
262 :
263 : // A class for building an access_array on an obstack. It automatically
264 : // frees any in-progress array if the build attempt fails before finish ()
265 : // has been called.
266 79377845 : class access_array_builder : public obstack_watermark
267 : {
268 : public:
269 79377845 : using obstack_watermark::obstack_watermark;
270 :
271 : // Make sure that the array has enough for NUM_ACCESSES accesses.
272 : void reserve (unsigned int num_accesses);
273 :
274 : // Add ACCESS to the end of the array that we're building, given that
275 : // reserve () has already made room.
276 : void quick_push (access_info *access);
277 :
278 : // Finish and return the new array. The array survives the destruction
279 : // of the builder.
280 : array_slice<access_info *> finish ();
281 : };
282 :
283 : // An access_info that represents the use of a resource in either a phi node
284 : // or an instruction. It records which set_info (if any) provides the
285 : // resource's value.
286 : class use_info : public access_info
287 : {
288 : // Overall size: 5 LP64 words.
289 : friend class set_info;
290 : friend class function_info;
291 :
292 : public:
293 : // Return true if the access occurs in an instruction rather than a phi node.
294 : // The instruction might be a debug instruction or a nondebug instruction.
295 973117240 : bool is_in_any_insn () const { return m_insn_or_phi.is_first (); }
296 :
297 : // Return true if the access occurs in a nondebug instruction,
298 : // false if it occurs in a debug instruction or a phi node.
299 5945438851 : bool is_in_nondebug_insn () const { return !m_is_in_debug_insn_or_phi; }
300 :
301 : // Return true if the instruction occurs in a debug instruction.
302 : bool is_in_debug_insn () const;
303 :
304 : // Return true if the access occurs in a phi node rather than in an
305 : // instruction.
306 1312655550 : bool is_in_phi () const { return m_insn_or_phi.is_second (); }
307 :
308 : // Return true if the access occurs in a debug instruction or a phi node,
309 : // false if it occurs in a nondebug instruction.
310 1198171620 : bool is_in_debug_insn_or_phi () const { return m_is_in_debug_insn_or_phi; }
311 :
312 : // Return the instruction that uses the resource. Only valid is
313 : // is_in_any_insn ().
314 2251680018 : insn_info *insn () const { return m_insn_or_phi.known_first (); }
315 :
316 : // Return the phi node that uses the resource. Only valid if is_in_phi ().
317 46766912 : phi_info *phi () const { return m_insn_or_phi.known_second (); }
318 :
319 : // Return the basic block that contains the access.
320 : bb_info *bb () const;
321 :
322 : // Return the extended basic block that contains the access.
323 : ebb_info *ebb () const;
324 :
325 : // Return the set_info whose result the access uses, or null if the
326 : // value of the resource is completely undefined.
327 : //
328 : // The value is undefined if the use is completely upwards exposed
329 : // (i.e. has no preceding definition) or if the preceding definition
330 : // is a clobber rather than a set.
331 : //
332 : // The mode of the definition can be different from the mode of the use;
333 : // for example, a hard register might be set in DImode and used in SImode.
334 3042926233 : set_info *def () const { return m_def; }
335 :
336 : // Return the previous and next uses of the definition. See set_info
337 : // for details about the ordering.
338 : //
339 : // These routines are only meaningful when def () is nonnull.
340 : use_info *prev_use () const;
341 : use_info *next_use () const;
342 :
343 : // Return the next use by a nondebug instruction, or null if none.
344 : //
345 : // This is only valid if is_in_nondebug_insn (). It is equivalent to,
346 : // but more efficient than:
347 : //
348 : // next_use () && next_use ()->is_in_nondebug_insn ()
349 : // ? next_use () : nullptr
350 : use_info *next_nondebug_insn_use () const;
351 :
352 : // Return the next use by an instruction, or null if none. The use might
353 : // be by a debug instruction or a nondebug instruction.
354 : //
355 : // This is only valid if is_in_any_insn (). It is equivalent to:
356 : //
357 : // next_use () && next_use ()->is_in_any_insn () ? next_use () : nullptr
358 : use_info *next_any_insn_use () const;
359 :
360 : // Return the next use by a debug instruction, or null if none.
361 : // This is only valid if is_in_debug_insn ().
362 : use_info *next_debug_insn_use () const;
363 :
364 : // Return the previous use by a phi node in the list, or null if none.
365 : //
366 : // This is only valid if is_in_phi (). It is equivalent to:
367 : //
368 : // prev_use () && prev_use ()->is_in_phi () ? prev_use () : nullptr
369 : use_info *prev_phi_use () const;
370 :
371 : // Return true if this is the first use of the definition. See set_info
372 : // for details about the ordering.
373 : //
374 : // This routine is only meaningful when def () is nonnull.
375 : bool is_first_use () const;
376 :
377 : // Return true if this is the last use of the definition. See set_info
378 : // for details about the ordering.
379 : //
380 : // This routine is only meaningful when def () is nonnull.
381 : bool is_last_use () const;
382 :
383 : // Print a description of def () to PP.
384 : void print_def (pretty_printer *pp) const;
385 :
386 : // Print a description of the location of the use to PP.
387 : void print_location (pretty_printer *pp) const;
388 :
389 : // Print a description of the use to PP under the control of
390 : // PP_ACCESS_* flags FLAGS.
391 : void print (pretty_printer *pp,
392 : unsigned int flags = PP_ACCESS_DEFAULT) const;
393 :
394 : private:
395 : // If we only create a set_info splay tree for sets that are used by
396 : // three instructions or more, then only about 16% of uses need to be in
397 : // a splay tree. It is therefore more memory-efficient to use separate
398 : // nodes for the splay tree, instead of storing the child nodes
399 : // directly in the use_info.
400 :
401 : // Make insn_info the first (and thus directly-encoded) choice since
402 : // insn () is read much more often than phi ().
403 : using insn_or_phi = pointer_mux<insn_info, phi_info>;
404 :
405 : // The use belongs to a list that is partitioned into three sections:
406 : //
407 : // (1) all uses in nondebug instructions, in reverse postorder
408 : //
409 : // (2) all uses in debug instructions, in reverse postorder
410 : //
411 : // (3) all phi nodes, in no particular order.
412 : //
413 : // In order to preserve memory:
414 : //
415 : // - The set_info just has a pointer to the first use.
416 : //
417 : // - The first use's "prev" pointer points to the last use.
418 : //
419 : // - The last use's "next" pointer points to the last use in a nondebug
420 : // instruction, or null if there are no such uses.
421 : using last_use_or_prev_use = pointer_mux<use_info>;
422 : using last_nondebug_insn_use_or_next_use = pointer_mux<use_info>;
423 :
424 : use_info (insn_or_phi, resource_info, set_info *);
425 :
426 : use_info *last_use () const;
427 : use_info *last_nondebug_insn_use () const;
428 : bool calculate_is_last_nondebug_insn_use () const;
429 :
430 : void record_reference (rtx_obj_reference, bool);
431 : void set_insn (insn_info *);
432 59755410 : void set_def (set_info *set) { m_def = set; }
433 77418828 : void set_is_live_out_use (bool value) { m_is_live_out_use = value; }
434 : void copy_prev_from (use_info *);
435 : void copy_next_from (use_info *);
436 : void set_last_use (use_info *);
437 : void set_prev_use (use_info *);
438 : void set_last_nondebug_insn_use (use_info *);
439 : void set_next_use (use_info *);
440 : void clear_use_links ();
441 : bool has_use_links ();
442 : bool check_integrity ();
443 :
444 : // The location of the use.
445 : insn_or_phi m_insn_or_phi;
446 :
447 : // The overloaded "prev" and "next" pointers, as described above.
448 : last_use_or_prev_use m_last_use_or_prev_use;
449 : last_nondebug_insn_use_or_next_use m_last_nondebug_insn_use_or_next_use;
450 :
451 : // The value of def ().
452 : set_info *m_def;
453 : };
454 :
455 : // Iterators for lists of uses.
456 : using use_iterator = list_iterator<use_info, &use_info::next_use>;
457 : using reverse_use_iterator = list_iterator<use_info, &use_info::prev_use>;
458 :
459 : // Like use_iterator, but specifically for uses by nondebug instructions,
460 : // uses by any kind of instruction, and uses by phi nodes respectively.
461 : // These iterators allow a nullptr end point even if there are other types
462 : // of use in the same definition.
463 : using nondebug_insn_use_iterator
464 : = list_iterator<use_info, &use_info::next_nondebug_insn_use>;
465 : using debug_insn_use_iterator
466 : = list_iterator<use_info, &use_info::next_debug_insn_use>;
467 : using any_insn_use_iterator
468 : = list_iterator<use_info, &use_info::next_any_insn_use>;
469 : using phi_use_iterator = list_iterator<use_info, &use_info::prev_phi_use>;
470 :
471 : // A view of an access_array in which every entry is known to be a use_info.
472 : using use_array = const_derived_container<use_info *, access_array>;
473 :
474 : // An access_info that describes a definition of a resource. The definition
475 : // can be a set or a clobber; the difference is that a set provides a known
476 : // and potentially useful value, while a clobber provides an unknown and
477 : // unusable value.
478 : //
479 : // Every definition is associated with an insn_info. All definitions of
480 : // a given resource are stored in a linked list, maintained in reverse
481 : // postorder.
482 : class def_info : public access_info
483 : {
484 : // Overall size: 4 LP64 words
485 : friend class function_info;
486 : friend class clobber_group;
487 :
488 : public:
489 : // Return the instruction that contains the definition.
490 1663114197 : insn_info *insn () const { return m_insn; }
491 :
492 : // Return the basic block that contains the definition.
493 : bb_info *bb () const;
494 :
495 : // Return the extended basic block that contains the access.
496 : ebb_info *ebb () const;
497 :
498 : // Return the previous and next definitions of the same resource,
499 : // in reverse postorder, or null if no such definition exists.
500 : def_info *prev_def () const;
501 : def_info *next_def () const;
502 :
503 : // Return true if this is the first definition in the list.
504 : bool is_first_def () const;
505 :
506 : // Return true if this is the last definition in the list.
507 : bool is_last_def () const;
508 :
509 : // Print the location of the definition to PP.
510 : void print_location (pretty_printer *pp) const;
511 :
512 : // Print a unique identifier for this definition to PP. The identifier has
513 : // the form <resource>:<insn uid>.
514 : void print_identifier (pretty_printer *pp) const;
515 :
516 : protected:
517 : def_info (insn_info *insn, resource_info resource, access_kind kind);
518 :
519 : private:
520 : // In order to preserve memory, the list head only points to the first
521 : // definition in the list. The "prev" entry of the first definition
522 : // then points to the last definition.
523 : using last_def_or_prev_def = pointer_mux<def_info>;
524 :
525 : // For similar memory-saving reasons, if we want to create a splay tree
526 : // of accesses to a resource, we hang the root off the "next" entry of
527 : // the last definition in the list.
528 : using splay_root_or_next_def = pointer_mux<def_node, def_info>;
529 :
530 9623201 : void set_insn (insn_info *insn) { m_insn = insn; }
531 :
532 : def_info *last_def () const;
533 : def_node *splay_root () const;
534 :
535 : void record_reference (rtx_obj_reference, bool);
536 : void copy_prev_from (def_info *);
537 : void copy_next_from (def_info *);
538 : void set_last_def (def_info *);
539 : void set_prev_def (def_info *);
540 : void set_splay_root (def_node *);
541 : void set_next_def (def_info *);
542 : void clear_def_links ();
543 : bool has_def_links ();
544 :
545 : // The location of the definition.
546 : insn_info *m_insn;
547 :
548 : // The overloaded "prev" and "next" pointers, as described above.
549 : last_def_or_prev_def m_last_def_or_prev_def;
550 : splay_root_or_next_def m_splay_root_or_next_def;
551 : };
552 :
553 : // Iterators for lists of definitions.
554 : using def_iterator = list_iterator<def_info, &def_info::next_def>;
555 : using reverse_def_iterator = list_iterator<def_info, &def_info::prev_def>;
556 :
557 : // A view of an access_array in which every entry is known to be a
558 : // def_info.
559 : using def_array = const_derived_container<def_info *, access_array>;
560 :
561 : // A def_info that sets the resource to a value that is both
562 : // unknown and not useful. This is only ever used for registers,
563 : // since memory always has some useful contents.
564 : //
565 : // Neighboring clobbers are grouped into clobber_groups, so that it's
566 : // possibly to skip over all neighboring clobbers in a single step.
567 : class clobber_info : public def_info
568 : {
569 : // Overall size: 8 LP64 words
570 : friend class default_splay_tree_accessors<clobber_info *>;
571 : friend class default_splay_tree_accessors_with_parent<clobber_info *>;
572 : friend class function_info;
573 : friend class clobber_group;
574 :
575 : public:
576 : using splay_tree = default_rootless_splay_tree<clobber_info *>;
577 :
578 : // Return true if the clobber belongs to a clobber_group, false if it
579 : // is standalone.
580 113921471 : bool is_in_group () const { return m_group; }
581 :
582 : // Return the group that the clobber is in, or null if none.
583 : //
584 : // Complexity: amortized O(1), worst case O(N), where N is the number
585 : // of clobbers in the containing clobber_group.
586 : clobber_group *group () const;
587 :
588 : // Print a description of the clobber to PP under the control of
589 : // PP_ACCESS_* flags FLAGS.
590 : void print (pretty_printer *pp,
591 : unsigned int flags = PP_ACCESS_DEFAULT) const;
592 :
593 : private:
594 : // Once normal call clobbers are taken out of the equation by
595 : // insn_call_clobbers_notes, clobber_infos account for roughly 6% of all
596 : // def_infos, with the rest being set_infos. clobber_infos are
597 : // therefore much less size-sensitive than set_infos are.
598 : //
599 : // As noted above, we want to group neighboring clobbers together so that
600 : // we can quickly step over them to find the previous or next "real" set.
601 : // We also want to be able to split the group in sublinear time,
602 : // for example when inserting a set/use pair between two clobbers
603 : // in a group.
604 : //
605 : // So:
606 : //
607 : // - Clobbers need to have ready access to their group, so that we
608 : // can cheaply skip over the whole group. This means that they
609 : // need a group pointer.
610 : //
611 : // - We need to be able to update the group pointer lazily, so that
612 : // the cost of updating it is counted against accesses to the clobbers
613 : // that need updating.
614 : //
615 : // We also want to be able to insert clobbers into a group in
616 : // amortized logarithmic time.
617 : //
618 : // We therefore use a splay tree to represent the clobbers in a group,
619 : // with the nodes storing their parent node. It is then possible to
620 : // perform splay operations without first getting hold of the root.
621 : // The root of the splay tree always has a valid, up-to-date group,
622 : // so lazy group updates can get the new group from there.
623 : //
624 : // Roughly 90% of clobbers have a neighboring definition in the same
625 : // block, which means that most need to be stored in a splay tree.
626 : // We therefore store the splay tree fields directly in the clobber_info
627 : // rather than using a separate node object.
628 :
629 : clobber_info (insn_info *, unsigned int);
630 :
631 1149551 : void set_group (clobber_group *group) { m_group = group; }
632 : void update_group (clobber_group *);
633 : clobber_group *recompute_group ();
634 :
635 : // The child and parent nodes in the splay tree.
636 : clobber_info *m_children[2];
637 : clobber_info *m_parent;
638 :
639 : // The last known value of group (), which might now be out of date.
640 : clobber_group *m_group;
641 : };
642 :
643 : using clobber_tree = clobber_info::splay_tree::rooted;
644 :
645 : // A def_info that sets the resource to a useful value. It records
646 : // all uses of the value in a linked list. The list is partitioned
647 : // into three sections:
648 : //
649 : // (1) all uses by nondebug instructions, in reverse postorder, followed by
650 : // (2) all uses by debug instructions, in reverse postorder, followed by
651 : // (3) all uses by phi nodes, in no particular order.
652 : //
653 : // There are two cases:
654 : //
655 : // - If we know in advance that there is a single definition of a resource R
656 : // and therefore decide not to use phi nodes for R, (1) and (2) contain
657 : // all uses of R, regardless of which blocks contain the uses. (3) is
658 : // then empty.
659 : //
660 : // - Otherwise, (1) only contains uses in the same extended basic block
661 : // as the definition, and it is terminated by a use that marks the end
662 : // of the live range for the EBB. In other words, if the resource dies
663 : // in the EBB, the last use by a nondebug instruction marks the point at
664 : // which it dies, otherwise there is a fake live-out use at the end of
665 : // the EBB.
666 : //
667 : // Since debug instructions should not affect codegen, they opportunisticly
668 : // attach to the same set_info as nondebug instructions where possible.
669 : // If a nondebug instruction would attach to a degenerate phi and if no
670 : // such phi exists, debug instructions instead attach to whichever set_info
671 : // provides the value, regardless of where that set_info is.
672 : class set_info : public def_info
673 : {
674 : // Overall size: 6 LP64 words.
675 : friend class function_info;
676 : using use_splay_tree = splay_tree<use_info *>;
677 :
678 : public:
679 : // Return the first and last uses of the set, or null if the list is empty.
680 : // See the comment above for details about the order.
681 1511965201 : use_info *first_use () const { return m_first_use; }
682 : use_info *last_use () const;
683 :
684 : // Return the first and last uses of the set by nondebug instructions,
685 : // or null if there are no such uses. The uses are in reverse postorder.
686 : use_info *first_nondebug_insn_use () const;
687 : use_info *last_nondebug_insn_use () const;
688 :
689 : // Return the first use of the set by debug instructions, or null if
690 : // there is no such use.
691 : use_info *first_debug_insn_use () const;
692 :
693 : // Return the first use of the set by any kind of instruction, or null
694 : // if there are no such uses. The uses are in the order described above.
695 : use_info *first_any_insn_use () const;
696 :
697 : // Return the last use of the set by phi inputs, or null if there are no
698 : // such uses. The phi input uses are in no particular order.
699 : use_info *last_phi_use () const;
700 :
701 : // Return true if at least one nondebug instruction or phi node uses
702 : // the set's result. This is equivalent to testing whether the set is
703 : // ever live.
704 : bool has_nondebug_uses () const;
705 :
706 : // Return true if anything uses the set's result. Note that this includes
707 : // uses by debug instructions, so it should not be used for optimization
708 : // decisions.
709 14108560 : bool has_any_uses () const { return m_first_use; }
710 :
711 : // Return true if at least one nondebug instruction uses the set's result.
712 : bool has_nondebug_insn_uses () const;
713 :
714 : // Return true if at least one phi node uses the set's result.
715 : bool has_phi_uses () const;
716 :
717 : // If there is exactly one nondebug use of the set's result, return that use,
718 : // otherwise return null. The use might be in an instruction or in a phi
719 : // node.
720 : use_info *single_nondebug_use () const;
721 :
722 : // If exactly one nondebug instruction uses the set's result, return the use
723 : // by that instruction, otherwise return null.
724 : use_info *single_nondebug_insn_use () const;
725 :
726 : // If exactly one phi node uses the set's result, return the use by that phi
727 : // node, otherwise return null.
728 : use_info *single_phi_use () const;
729 :
730 : // Return true if the set and its uses are contained within a single
731 : // extended basic block, with the set coming first. This implies
732 : // that all uses are by instructions rather than phi nodes.
733 : bool is_local_to_ebb () const;
734 :
735 : // List all the uses of the set, in the order described above.
736 : iterator_range<use_iterator> all_uses () const;
737 :
738 : // Return uses () in reverse order.
739 : iterator_range<reverse_use_iterator> reverse_all_uses () const;
740 :
741 : // List the uses of the set by nondebug instructions, in reverse postorder.
742 : iterator_range<nondebug_insn_use_iterator> nondebug_insn_uses () const;
743 :
744 : // List the uses of the set by debug instructions, in reverse postorder.
745 : iterator_range<debug_insn_use_iterator> debug_insn_uses () const;
746 :
747 : // Return nondebug_insn_uses () in reverse order.
748 : iterator_range<reverse_use_iterator> reverse_nondebug_insn_uses () const;
749 :
750 : // List the uses of the set by any kind of instruction. The list follows
751 : // the order described above.
752 : iterator_range<any_insn_use_iterator> all_insn_uses () const;
753 :
754 : // List the uses of the set by phi nodes, in no particular order.
755 : // There is therefore no reversed equivalent of this list.
756 : iterator_range<phi_use_iterator> phi_uses () const;
757 :
758 : // Print a description of the set to PP under the control of
759 : // PP_ACCESS_* flags FLAGS.
760 : void print (pretty_printer *pp,
761 : unsigned int flags = PP_ACCESS_DEFAULT) const;
762 :
763 : protected:
764 : set_info (insn_info *, resource_info, access_kind);
765 :
766 : // Print information about uses () to PP, continuing information printed
767 : // about the set itself.
768 : void print_uses_on_new_lines (pretty_printer *pp) const;
769 :
770 : private:
771 : // Sets (including phis) account for about 94% of all definitions
772 :
773 : set_info (insn_info *, resource_info);
774 :
775 : void set_first_use (use_info *);
776 :
777 : // The first use in the list.
778 : use_info *m_first_use;
779 :
780 : // The root of a splay tree of all uses, built lazily when we first
781 : // think it's needed.
782 : use_splay_tree m_use_tree;
783 : };
784 :
785 : // A set_info for an on-the-side phi node. The phi node is attached
786 : // to an extended basic block EBB and has one input for each incoming edge.
787 : // The inputs are represented as an array of use_infos, with input I
788 : // corresponding to EDGE_PRED (EBB->first_bb ()->cfg_bb (), I).
789 : //
790 : // Each phi node has a densely-allocated unique identifier, which is intended
791 : // to be suitable for bitmaps or sbitmaps.
792 : //
793 : // All the phi nodes in an extended basic block are chained together
794 : // into a linked list. The list has no particular order.
795 : class phi_info : public set_info
796 : {
797 : // Overall size: 8 LP64 words
798 : friend class function_info;
799 :
800 : public:
801 : // Return the previous and next phi nodes in the extended basic block's list,
802 : // or null if none.
803 10635051 : phi_info *prev_phi () const { return m_prev_phi; }
804 206317206 : phi_info *next_phi () const { return m_next_phi; }
805 :
806 : // Return the number of phi inputs. This is 1 for degenerate phis,
807 : // otherwise it is equal to the number of incoming edges.
808 : unsigned int num_inputs () const { return m_num_inputs; }
809 :
810 : // Return true if the phi node is degenerate, i.e. if it has only a
811 : // single input.
812 200093295 : bool is_degenerate () const { return m_num_inputs == 1; }
813 :
814 : // Return the phi node's unique identifier.
815 402606677 : unsigned int uid () const { return m_uid; }
816 :
817 : // Return the array of inputs. For degenerate phi nodes, this array contains
818 : // a single element, otherwise it has one input per incoming edge,
819 : // with element E corresponding to incoming edge E.
820 : use_array inputs () const;
821 :
822 : // Return the use_info that describes the phi input for incoming edge E.
823 : use_info *input_use (unsigned int e) const;
824 :
825 : // Return the value of resource () on incoming edge E, or null if the
826 : // value is completely undefined for that edge.
827 : set_info *input_value (unsigned int e) const;
828 :
829 : // Print a description of the phi node to PP under the control of
830 : // PP_ACCESS_* flags FLAGS.
831 : void print (pretty_printer *pp,
832 : unsigned int flags = PP_ACCESS_DEFAULT) const;
833 :
834 : private:
835 : phi_info (insn_info *insn, resource_info resource, unsigned int uid);
836 :
837 : void make_degenerate (use_info *);
838 : void set_inputs (use_array inputs);
839 62254907 : void set_prev_phi (phi_info *prev_phi) { m_prev_phi = prev_phi; }
840 106948563 : void set_next_phi (phi_info *next_phi) { m_next_phi = next_phi; }
841 10635051 : void clear_phi_links () { m_prev_phi = m_next_phi = nullptr; }
842 : bool has_phi_links () { return m_prev_phi || m_next_phi; }
843 :
844 : // The values returned by the accessors above.
845 : unsigned int m_uid;
846 : unsigned int m_num_inputs;
847 : union
848 : {
849 : access_info *const *m_inputs;
850 : access_info *m_single_input;
851 : };
852 : phi_info *m_prev_phi;
853 : phi_info *m_next_phi;
854 : };
855 :
856 : // An iterator for lists of phi nodes.
857 : using phi_iterator = list_iterator<phi_info, &phi_info::next_phi>;
858 :
859 : // One node in a splay tree of definitions. This base class represents
860 : // a single def_info, but it is structured to allow derived classes
861 : // to add a range.
862 : class def_node
863 : {
864 : // Size: 3 LP64 words.
865 : friend class function_info;
866 : friend class default_splay_tree_accessors<def_node *>;
867 :
868 : public:
869 : // Return the first definition that the node represents.
870 : def_info *first_def () const;
871 :
872 : // Return which type of access first_def () is.
873 10374722 : bool contains_clobber () const { return m_clobber_or_set.is_first (); }
874 0 : bool contains_set () const { return m_clobber_or_set.is_second (); }
875 :
876 : protected:
877 : // More nodes are clobbers rather than sets, so put clobbers first.
878 : // Neither choice can be null.
879 : using clobber_or_set = pointer_mux<clobber_info, set_info>;
880 :
881 : // Construct a node that represents FIRST_DEF (and possibly later
882 : // definitions too, if called from a derived class).
883 : def_node (clobber_or_set first_def);
884 :
885 : // The first definition in the node.
886 : clobber_or_set m_clobber_or_set;
887 :
888 : private:
889 : // The splay tree child nodes.
890 : def_node *m_children[2];
891 : };
892 :
893 : // One node in a splay tree of def_infos, representing a single set_info.
894 : class set_node : public def_node
895 : {
896 : // Overall size: 3 LP64 words.
897 : friend class function_info;
898 :
899 : public:
900 : // Return the set that the node contains.
901 : set_info *set () const { return m_clobber_or_set.known_second (); }
902 :
903 : // Print a description of the node to PP.
904 : void print (pretty_printer *pp) const;
905 :
906 : private:
907 : // Construct a node for SET.
908 16568393 : set_node (set_info *set) : def_node (set) {}
909 : };
910 :
911 : // One node in a splay tree of def_infos. This class represents
912 : // a list of contiguous clobber_infos, in execution order.
913 : class clobber_group : public def_node
914 : {
915 : // Overall size: 5 LP64 words.
916 : friend class function_info;
917 :
918 : public:
919 : // Return the first and last clobbers in the group. The results are
920 : // always nonnull.
921 : clobber_info *first_clobber () const;
922 102164332 : clobber_info *last_clobber () const { return m_last_clobber; }
923 :
924 : // Return the last clobber before INSN in the group, or null if none.
925 : clobber_info *prev_clobber (insn_info *insn) const;
926 :
927 : // Return the next clobber after INSN in the group, or null if none.
928 : clobber_info *next_clobber (insn_info *insn) const;
929 :
930 : // Return true if this group has been replaced by new clobber_groups.
931 95090855 : bool has_been_superceded () const { return !m_last_clobber; }
932 :
933 : // Return a list of the clobbers in the group, in execution order.
934 : iterator_range<def_iterator> clobbers () const;
935 :
936 : // Print a description of the group to PP.
937 : void print (pretty_printer *pp) const;
938 :
939 : private:
940 : clobber_group (clobber_info *);
941 : clobber_group (clobber_info *, clobber_info *, clobber_info *);
942 :
943 : // Set the values of first_clobber () and last_clobber ().
944 290142 : void set_first_clobber (clobber_info *c) { m_clobber_or_set = c; }
945 163935 : void set_last_clobber (clobber_info *c) { m_last_clobber = c; }
946 :
947 : int lookup_clobber (insn_info *) const;
948 :
949 : // The value returned by last_clobber ().
950 : clobber_info *m_last_clobber;
951 :
952 : // A splay tree that contains all the clobbers in the group.
953 : // The root of the splay tree always has an up-to-date group
954 : // pointer, but the other clobbers in the tree might not.
955 : clobber_tree m_clobber_tree;
956 : };
957 :
958 : // A splay tree in which one node represents a standalone set_info or a
959 : // range of consecutive clobber_infos. The nodes follow execution order
960 : // and maintain the invariant that no two groups of clobber_infos appear
961 : // next to each other (instead, the groups are merged).
962 : using def_splay_tree = default_splay_tree<def_node *>;
963 :
964 : // This type represents a choice between:
965 : //
966 : // (1) a single definition of a resource
967 : // (2) a node in a def_splay_tree that represents either a single
968 : // set or a group of clobbers.
969 : class def_mux : public pointer_mux<def_info, def_node>
970 : {
971 : using parent = pointer_mux<def_info, def_node>;
972 :
973 : // Provide the same constructors as the pointer_mux.
974 6145720 : using parent::parent;
975 :
976 : public:
977 : // Return the first definition associated with this mux. If the mux holds
978 : // a single definition, the result is that definition. If the mux holds
979 : // a clobber_group, the result is the first clobber in the group.
980 : def_info *first_def () const;
981 :
982 : // Return the last definition associated with this mux. If the mux holds
983 : // a single definition, the result is that definition. If the mux holds
984 : // a clobber_group, the result is the last clobber in the group.
985 : def_info *last_def () const;
986 :
987 : // If the pointer represents a set_info, return that set_info,
988 : // otherwise return null.
989 : set_info *set () const;
990 : };
991 :
992 : // This class represents the result of looking up the definition of a
993 : // resource at a particular point, here referred to as point P.
994 : // There are four states:
995 : //
996 : // - MUX is null if there were no definitions to search.
997 : //
998 : // - Otherwise, COMPARISON is 0 if we found a definition at P or a
999 : // clobber_group that spans P. MUX then contains this definition
1000 : // or clobber_group.
1001 : //
1002 : // - Otherwise, COMPARISON is greater than 0 if we found the definition
1003 : // that precedes P or the group of clobbers that precedes P. MUX then
1004 : // contains this definition or clobber_group.
1005 : //
1006 : // - Otherwise, COMPARISON is less than zero and we found the definition
1007 : // that follows P, or the group of clobbers that follows P. MUX then
1008 : // contains this definition or clobber_group.
1009 : class def_lookup
1010 : {
1011 : public:
1012 : // If we found a clobber_group that spans P, return the definition
1013 : // that precedes the start of the group, or null if none.
1014 : //
1015 : // Otherwise, return the last definition that occurs before P,
1016 : // or null if none.
1017 : def_info *last_def_of_prev_group () const;
1018 :
1019 : // If we found a clobber_group that spans P, return the definition
1020 : // that follows the end of the group, or null if none.
1021 : //
1022 : // Otherwise, return the first definition that occurs after P,
1023 : // or null if none.
1024 : def_info *first_def_of_next_group () const;
1025 :
1026 : // If we found a set_info at P, return that set_info, otherwise return null.
1027 : set_info *matching_set () const;
1028 :
1029 : // If we found a set_info at P, return that set_info, otherwise return
1030 : // prev_def ().
1031 : def_info *matching_set_or_last_def_of_prev_group () const;
1032 :
1033 : // If we found a set_info at P, return that set_info, otherwise return
1034 : // next_def ().
1035 : def_info *matching_set_or_first_def_of_next_group () const;
1036 :
1037 : // P is the location of INSN. Return the last definition (of any kind)
1038 : // that occurs before INSN, or null if none.
1039 : def_info *prev_def (insn_info *insn) const;
1040 :
1041 : // P is the location of INSN. Return the next definition (of any kind)
1042 : // that occurs after INSN, or null if none.
1043 : def_info *next_def (insn_info *insn) const;
1044 :
1045 : def_mux mux;
1046 : int comparison;
1047 : };
1048 :
1049 : // This class represents the result of looking for a use of a particular
1050 : // definition at a particular point, here referred to as point P.
1051 : // There are four states:
1052 : //
1053 : // - USE is null if the definition has no uses.
1054 : //
1055 : // - Otherwise, COMPARISON is 0 if we found a definition at P. USE then
1056 : // contains this use.
1057 : //
1058 : // - Otherwise, COMPARISON is greater than 0 if we found a use that precedes P.
1059 : // USE then contains this use.
1060 : //
1061 : // - Otherwise, COMPARISON is less than zero and we found a use that follows P.
1062 : // USE then contains this use.
1063 : class use_lookup
1064 : {
1065 : public:
1066 : // If we found a use at P, return that use, otherwise return null.
1067 : use_info *matching_use () const;
1068 :
1069 : // If we found a use at P, return that use, otherwise return prev_use ().
1070 : use_info *matching_or_prev_use () const;
1071 :
1072 : // If we found a use at P, return that use, otherwise return next_use ().
1073 : use_info *matching_or_next_use () const;
1074 :
1075 : // Return the last use that occurs before P, or null if none.
1076 : use_info *prev_use () const;
1077 :
1078 : // Return the first use that occurs after P, or null if none.
1079 : use_info *next_use () const;
1080 :
1081 : use_info *use;
1082 : int comparison;
1083 : };
1084 :
1085 : void pp_resource (pretty_printer *, resource_info);
1086 : void pp_access (pretty_printer *, const access_info *,
1087 : unsigned int flags = PP_ACCESS_DEFAULT);
1088 : void pp_accesses (pretty_printer *, access_array,
1089 : unsigned int flags = PP_ACCESS_DEFAULT);
1090 : void pp_def_node (pretty_printer *, const def_node *);
1091 : void pp_def_mux (pretty_printer *, def_mux);
1092 : void pp_def_lookup (pretty_printer *, def_lookup);
1093 : void pp_def_splay_tree (pretty_printer *, def_splay_tree);
1094 :
1095 : }
1096 :
1097 : void dump (FILE *, rtl_ssa::resource_info);
1098 : void dump (FILE *, const rtl_ssa::access_info *,
1099 : unsigned int flags = rtl_ssa::PP_ACCESS_DEFAULT);
1100 : void dump (FILE *, rtl_ssa::access_array,
1101 : unsigned int flags = rtl_ssa::PP_ACCESS_DEFAULT);
1102 : void dump (FILE *, const rtl_ssa::def_node *);
1103 : void dump (FILE *, rtl_ssa::def_mux);
1104 : void dump (FILE *, rtl_ssa::def_lookup);
1105 : void dump (FILE *, rtl_ssa::def_splay_tree);
1106 :
1107 : void DEBUG_FUNCTION debug (const rtl_ssa::resource_info *);
1108 : void DEBUG_FUNCTION debug (const rtl_ssa::access_info *);
1109 : void DEBUG_FUNCTION debug (const rtl_ssa::access_array);
1110 : void DEBUG_FUNCTION debug (const rtl_ssa::def_node *);
1111 : void DEBUG_FUNCTION debug (const rtl_ssa::def_mux &);
1112 : void DEBUG_FUNCTION debug (const rtl_ssa::def_lookup &);
1113 : void DEBUG_FUNCTION debug (const rtl_ssa::def_splay_tree &);
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