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[official-gcc.git] / gcc / rtl-ssa / accesses.h
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1 // Access-related classes for RTL SSA -*- C++ -*-
2 // Copyright (C) 2020-2021 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.
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.
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/>.
20 namespace rtl_ssa {
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;
31 // Used as a boolean argunent to certain routines.
32 enum class ignore_clobbers { NO, YES };
34 // Represents something that the SSA form tracks: either a register
35 // or memory.
36 class resource_info
38 public:
39 // Return true if this resource represents memory.
40 bool is_mem () const { return regno == MEM_REGNO; }
42 // Return true if this resource represents a register.
43 bool is_reg () const { return regno != MEM_REGNO; }
45 // Print the name of the resource to PP.
46 void print_identifier (pretty_printer *pp) const;
48 // Possibly print additional information about the resource to PP.
49 void print_context (pretty_printer *pp) const;
51 // A combination of print_identifier and print_context.
52 void print (pretty_printer *pp) const;
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;
60 // The pseudo register or single hard register that the resource represents,
61 // or MEM_REGNO for memory.
62 unsigned int regno;
65 // For simplicity, we treat memory as a single unified entity.
66 const resource_info memory = { E_BLKmode, MEM_REGNO };
68 // Flags used when printing access_infos.
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;
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;
79 // Print additional properties about the access.
80 const unsigned int PP_ACCESS_INCLUDE_PROPERTIES = 1U << 2;
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);
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);
91 // The usual flags when printing a use_info from its user.
92 const unsigned int PP_ACCESS_USER = PP_ACCESS_INCLUDE_PROPERTIES;
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
100 // Set the resource to a useful value.
101 SET,
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,
107 // Set the resource to a value that is both unknown and not useful.
108 CLOBBER,
110 // Use the current value of the resource.
114 // A base class that represents an access to a resource.
115 class access_info
117 // Size: 1 LP64 word
118 friend class function_info;
120 public:
121 // Return the resource that is being accessed.
122 resource_info resource () const { return { m_mode, m_regno }; }
124 // Return true if the access is to memory.
125 bool is_mem () const { return m_regno == MEM_REGNO; }
127 // Return true if the access is to a register.
128 bool is_reg () const { return m_regno != MEM_REGNO; }
130 // If the access is to a register, return the register number,
131 // otherwise return MEM_REGNO.
132 unsigned int regno () const { return m_regno; }
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).
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 machine_mode mode () const { return m_mode; }
144 // Return the kind of access that this is.
145 access_kind kind () const { return m_kind; }
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 bool is_artificial () const { return m_is_artificial; }
151 // Return the opposite of is_artificial.
152 bool is_real () const { return !m_is_artificial; }
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;
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; }
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 bool is_call_clobber () const { return m_is_call_clobber; }
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 bool is_live_out_use () const { return m_is_live_out_use; }
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.
175 // There shouldn't be a need to check whether *all* uses occur within
176 // a MEM address, since in principle:
178 // A: (set (reg:SI R1) (mem:SI (post_inc:SI (reg:SI R2))))
180 // should be semantically equivalent to:
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)))])
185 // even though R2 occurs only in MEMs for A but occurs outside MEMs for B.
186 bool includes_address_uses () const { return m_includes_address_uses; }
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 bool includes_read_writes () const { return m_includes_read_writes; }
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 bool includes_subregs () const { return m_includes_subregs; }
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 bool includes_multiregs () const { return m_includes_multiregs; }
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 bool only_occurs_in_notes () const { return m_only_occurs_in_notes; }
207 protected:
208 access_info (resource_info, access_kind);
210 void print_prefix_flags (pretty_printer *) const;
211 void print_properties_on_new_lines (pretty_printer *) const;
213 private:
214 void set_mode (machine_mode mode) { m_mode = mode; }
216 // The values returned by the accessors above.
217 unsigned int m_regno;
218 access_kind m_kind : 8;
220 protected:
221 // The value returned by the accessors above.
222 unsigned int m_is_artificial : 1;
223 unsigned int m_is_set_with_nondebug_insn_uses : 1;
224 unsigned int m_is_pre_post_modify : 1;
225 unsigned int m_is_call_clobber : 1;
226 unsigned int m_is_live_out_use : 1;
227 unsigned int m_includes_address_uses : 1;
228 unsigned int m_includes_read_writes : 1;
229 unsigned int m_includes_subregs : 1;
230 unsigned int m_includes_multiregs : 1;
231 unsigned int m_only_occurs_in_notes : 1;
233 // True if this access is a use_insn that occurs in a nondebug instruction,
234 // and if there are no following uses by nondebug instructions. The next use
235 // is null, a use_info for a debug instruction, or a use_info for a phi node.
237 // Providing this helps to optimize use_info::next_nondebug_insn_use.
238 unsigned int m_is_last_nondebug_insn_use : 1;
240 // True if this access is a use_info for a debug instruction or
241 // a phi node.
242 unsigned int m_is_in_debug_insn_or_phi : 1;
244 private:
245 // Used as a flag during various update routines; has no long-lasting
246 // meaning.
247 unsigned int m_has_been_superceded : 1;
249 // Indicates that this access has been allocated on the function_info's
250 // temporary obstack and so is not (yet) part of the proper SSA form.
251 unsigned int m_is_temp : 1;
253 // Bits for future expansion.
254 unsigned int m_spare : 2;
256 // The value returned by the accessor above.
257 machine_mode m_mode : 8;
260 // A contiguous array of access_info pointers. Used to represent a
261 // (mostly small) number of definitions and/or uses.
262 using access_array = array_slice<access_info *const>;
264 // A class for building an access_array on an obstack. It automatically
265 // frees any in-progress array if the build attempt fails before finish ()
266 // has been called.
267 class access_array_builder : public obstack_watermark
269 public:
270 using obstack_watermark::obstack_watermark;
272 // Make sure that the array has enough for NUM_ACCESSES accesses.
273 void reserve (unsigned int num_accesses);
275 // Add ACCESS to the end of the array that we're building, given that
276 // reserve () has already made room.
277 void quick_push (access_info *access);
279 // Finish and return the new array. The array survives the destruction
280 // of the builder.
281 array_slice<access_info *> finish ();
284 // An access_info that represents the use of a resource in either a phi node
285 // or an instruction. It records which set_info (if any) provides the
286 // resource's value.
287 class use_info : public access_info
289 // Overall size: 5 LP64 words.
290 friend class set_info;
291 friend class function_info;
293 public:
294 // Return true if the access occurs in an instruction rather than a phi node.
295 // The instruction might be a debug instruction or a nondebug instruction.
296 bool is_in_any_insn () const { return m_insn_or_phi.is_first (); }
298 // Return true if the access occurs in a nondebug instruction,
299 // false if it occurs in a debug instruction or a phi node.
300 bool is_in_nondebug_insn () const { return !m_is_in_debug_insn_or_phi; }
302 // Return true if the instruction occurs in a debug instruction.
303 bool is_in_debug_insn () const;
305 // Return true if the access occurs in a phi node rather than in an
306 // instruction.
307 bool is_in_phi () const { return m_insn_or_phi.is_second (); }
309 // Return true if the access occurs in a debug instruction or a phi node,
310 // false if it occurs in a nondebug instruction.
311 bool is_in_debug_insn_or_phi () const { return m_is_in_debug_insn_or_phi; }
313 // Return the instruction that uses the resource. Only valid is
314 // is_in_any_insn ().
315 insn_info *insn () const { return m_insn_or_phi.known_first (); }
317 // Return the phi node that uses the resource. Only valid if is_in_phi ().
318 phi_info *phi () const { return m_insn_or_phi.known_second (); }
320 // Return the basic block that contains the access.
321 bb_info *bb () const;
323 // Return the extended basic block that contains the access.
324 ebb_info *ebb () const;
326 // Return the set_info whose result the access uses, or null if the
327 // value of the resource is completely undefined.
329 // The value is undefined if the use is completely upwards exposed
330 // (i.e. has no preceding definition) or if the preceding definition
331 // is a clobber rather than a set.
333 // The mode of the definition can be different from the mode of the use;
334 // for example, a hard register might be set in DImode and used in SImode.
335 set_info *def () const { return m_def; }
337 // Return the previous and next uses of the definition. See set_info
338 // for details about the ordering.
340 // These routines are only meaningful when def () is nonnull.
341 use_info *prev_use () const;
342 use_info *next_use () const;
344 // Return the next use by a nondebug instruction, or null if none.
346 // This is only valid if is_in_nondebug_insn (). It is equivalent to,
347 // but more efficient than:
349 // next_use () && next_use ()->is_in_nondebug_insn ()
350 // ? next_use () : nullptr
351 use_info *next_nondebug_insn_use () const;
353 // Return the next use by an instruction, or null if none. The use might
354 // be by a debug instruction or a nondebug instruction.
356 // This is only valid if is_in_any_insn (). It is equivalent to:
358 // next_use () && next_use ()->is_in_any_insn () ? next_use () : nullptr
359 use_info *next_any_insn_use () const;
361 // Return the previous use by a phi node in the list, or null if none.
363 // This is only valid if is_in_phi (). It is equivalent to:
365 // prev_use () && prev_use ()->is_in_phi () ? prev_use () : nullptr
366 use_info *prev_phi_use () const;
368 // Return true if this is the first use of the definition. See set_info
369 // for details about the ordering.
371 // This routine is only meaningful when def () is nonnull.
372 bool is_first_use () const;
374 // Return true if this is the last use of the definition. See set_info
375 // for details about the ordering.
377 // This routine is only meaningful when def () is nonnull.
378 bool is_last_use () const;
380 // Print a description of def () to PP.
381 void print_def (pretty_printer *pp) const;
383 // Print a description of the location of the use to PP.
384 void print_location (pretty_printer *pp) const;
386 // Print a description of the use to PP under the control of
387 // PP_ACCESS_* flags FLAGS.
388 void print (pretty_printer *pp,
389 unsigned int flags = PP_ACCESS_DEFAULT) const;
391 private:
392 // If we only create a set_info splay tree for sets that are used by
393 // three instructions or more, then only about 16% of uses need to be in
394 // a splay tree. It is therefore more memory-efficient to use separate
395 // nodes for the splay tree, instead of storing the child nodes
396 // directly in the use_info.
398 // Make insn_info the first (and thus directly-encoded) choice since
399 // insn () is read much more often than phi ().
400 using insn_or_phi = pointer_mux<insn_info, phi_info>;
402 // The use belongs to a list that is partitioned into three sections:
404 // (1) all uses in nondebug instructions, in reverse postorder
406 // (2) all uses in debug instructions, in reverse postorder
408 // (3) all phi nodes, in no particular order.
410 // In order to preserve memory:
412 // - The set_info just has a pointer to the first use.
414 // - The first use's "prev" pointer points to the last use.
416 // - The last use's "next" pointer points to the last use in a nondebug
417 // instruction, or null if there are no such uses.
418 using last_use_or_prev_use = pointer_mux<use_info>;
419 using last_nondebug_insn_use_or_next_use = pointer_mux<use_info>;
421 use_info (insn_or_phi, resource_info, set_info *);
423 use_info *last_use () const;
424 use_info *last_nondebug_insn_use () const;
425 bool calculate_is_last_nondebug_insn_use () const;
427 void record_reference (rtx_obj_reference, bool);
428 void set_insn (insn_info *);
429 void set_def (set_info *set) { m_def = set; }
430 void set_is_live_out_use (bool value) { m_is_live_out_use = value; }
431 void copy_prev_from (use_info *);
432 void copy_next_from (use_info *);
433 void set_last_use (use_info *);
434 void set_prev_use (use_info *);
435 void set_last_nondebug_insn_use (use_info *);
436 void set_next_use (use_info *);
437 void clear_use_links ();
438 bool has_use_links ();
439 bool check_integrity ();
441 // The location of the use.
442 insn_or_phi m_insn_or_phi;
444 // The overloaded "prev" and "next" pointers, as described above.
445 last_use_or_prev_use m_last_use_or_prev_use;
446 last_nondebug_insn_use_or_next_use m_last_nondebug_insn_use_or_next_use;
448 // The value of def ().
449 set_info *m_def;
452 // Iterators for lists of uses.
453 using use_iterator = list_iterator<use_info, &use_info::next_use>;
454 using reverse_use_iterator = list_iterator<use_info, &use_info::prev_use>;
456 // Like use_iterator, but specifically for uses by nondebug instructions,
457 // uses by any kind of instruction, and uses by phi nodes respectively.
458 // These iterators allow a nullptr end point even if there are other types
459 // of use in the same definition.
460 using nondebug_insn_use_iterator
461 = list_iterator<use_info, &use_info::next_nondebug_insn_use>;
462 using any_insn_use_iterator
463 = list_iterator<use_info, &use_info::next_any_insn_use>;
464 using phi_use_iterator = list_iterator<use_info, &use_info::prev_phi_use>;
466 // A view of an access_array in which every entry is known to be a use_info.
467 using use_array = const_derived_container<use_info *, access_array>;
469 // An access_info that describes a definition of a resource. The definition
470 // can be a set or a clobber; the difference is that a set provides a known
471 // and potentially useful value, while a clobber provides an unknown and
472 // unusable value.
474 // Every definition is associated with an insn_info. All definitions of
475 // a given resource are stored in a linked list, maintained in reverse
476 // postorder.
477 class def_info : public access_info
479 // Overall size: 4 LP64 words
480 friend class function_info;
481 friend class clobber_group;
483 public:
484 // Return the instruction that contains the definition.
485 insn_info *insn () const { return m_insn; }
487 // Return the basic block that contains the definition.
488 bb_info *bb () const;
490 // Return the extended basic block that contains the access.
491 ebb_info *ebb () const;
493 // Return the previous and next definitions of the same resource,
494 // in reverse postorder, or null if no such definition exists.
495 def_info *prev_def () const;
496 def_info *next_def () const;
498 // Return true if this is the first definition in the list.
499 bool is_first_def () const;
501 // Return true if this is the last definition in the list.
502 bool is_last_def () const;
504 // Print the location of the definition to PP.
505 void print_location (pretty_printer *pp) const;
507 // Print a unique identifier for this definition to PP. The identifier has
508 // the form <resource>:<insn uid>.
509 void print_identifier (pretty_printer *pp) const;
511 protected:
512 def_info (insn_info *insn, resource_info resource, access_kind kind);
514 private:
515 // In order to preserve memory, the list head only points to the first
516 // definition in the list. The "prev" entry of the first definition
517 // then points to the last definition.
518 using last_def_or_prev_def = pointer_mux<def_info>;
520 // For similar memory-saving reasons, if we want to create a splay tree
521 // of accesses to a resource, we hang the root off the "next" entry of
522 // the last definition in the list.
523 using splay_root_or_next_def = pointer_mux<def_node, def_info>;
525 void set_insn (insn_info *insn) { m_insn = insn; }
527 def_info *last_def () const;
528 def_node *splay_root () const;
530 void record_reference (rtx_obj_reference, bool);
531 void copy_prev_from (def_info *);
532 void copy_next_from (def_info *);
533 void set_last_def (def_info *);
534 void set_prev_def (def_info *);
535 void set_splay_root (def_node *);
536 void set_next_def (def_info *);
537 void clear_def_links ();
538 bool has_def_links ();
540 // The location of the definition.
541 insn_info *m_insn;
543 // The overloaded "prev" and "next" pointers, as described above.
544 last_def_or_prev_def m_last_def_or_prev_def;
545 splay_root_or_next_def m_splay_root_or_next_def;
548 // Iterators for lists of definitions.
549 using def_iterator = list_iterator<def_info, &def_info::next_def>;
550 using reverse_def_iterator = list_iterator<def_info, &def_info::prev_def>;
552 // A view of an access_array in which every entry is known to be a
553 // def_info.
554 using def_array = const_derived_container<def_info *, access_array>;
556 // A def_info that sets the resource to a value that is both
557 // unknown and not useful. This is only ever used for registers,
558 // since memory always has some useful contents.
560 // Neighboring clobbers are grouped into clobber_groups, so that it's
561 // possibly to skip over all neighboring clobbers in a single step.
562 class clobber_info : public def_info
564 // Overall size: 8 LP64 words
565 friend class default_splay_tree_accessors<clobber_info *>;
566 friend class default_splay_tree_accessors_with_parent<clobber_info *>;
567 friend class function_info;
568 friend class clobber_group;
570 public:
571 using splay_tree = default_rootless_splay_tree<clobber_info *>;
573 // Return true if the clobber belongs to a clobber_group, false if it
574 // is standalone.
575 bool is_in_group () const { return m_group; }
577 // Return the group that the clobber is in, or null if none.
579 // Complexity: amortized O(1), worst case O(N), where N is the number
580 // of clobbers in the containing clobber_group.
581 clobber_group *group () const;
583 // Print a description of the clobber to PP under the control of
584 // PP_ACCESS_* flags FLAGS.
585 void print (pretty_printer *pp,
586 unsigned int flags = PP_ACCESS_DEFAULT) const;
588 private:
589 // Once normal call clobbers are taken out of the equation by
590 // insn_call_clobbers_notes, clobber_infos account for roughly 6% of all
591 // def_infos, with the rest being set_infos. clobber_infos are
592 // therefore much less size-sensitive than set_infos are.
594 // As noted above, we want to group neighboring clobbers together so that
595 // we can quickly step over them to find the previous or next "real" set.
596 // We also want to be able to split the group in sublinear time,
597 // for example when inserting a set/use pair between two clobbers
598 // in a group.
600 // So:
602 // - Clobbers need to have ready access to their group, so that we
603 // can cheaply skip over the whole group. This means that they
604 // need a group pointer.
606 // - We need to be able to update the group pointer lazily, so that
607 // the cost of updating it is counted against accesses to the clobbers
608 // that need updating.
610 // We also want to be able to insert clobbers into a group in
611 // amortized logarithmic time.
613 // We therefore use a splay tree to represent the clobbers in a group,
614 // with the nodes storing their parent node. It is then possible to
615 // perform splay operations without first getting hold of the root.
616 // The root of the splay tree always has a valid, up-to-date group,
617 // so lazy group updates can get the new group from there.
619 // Roughly 90% of clobbers have a neighboring definition in the same
620 // block, which means that most need to be stored in a splay tree.
621 // We therefore store the splay tree fields directly in the clobber_info
622 // rather than using a separate node object.
624 clobber_info (insn_info *, unsigned int);
626 void set_group (clobber_group *group) { m_group = group; }
627 void update_group (clobber_group *);
628 clobber_group *recompute_group ();
630 // The child and parent nodes in the splay tree.
631 clobber_info *m_children[2];
632 clobber_info *m_parent;
634 // The last known value of group (), which might now be out of date.
635 clobber_group *m_group;
638 using clobber_tree = clobber_info::splay_tree::rooted;
640 // A def_info that sets the resource to a useful value. It records
641 // all uses of the value in a linked list. The list is partitioned
642 // into three sections:
644 // (1) all uses by nondebug instructions, in reverse postorder, followed by
645 // (2) all uses by debug instructions, in reverse postorder, followed by
646 // (3) all uses by phi nodes, in no particular order.
648 // There are two cases:
650 // - If we know in advance that there is a single definition of a resource R
651 // and therefore decide not to use phi nodes for R, (1) and (2) contain
652 // all uses of R, regardless of which blocks contain the uses. (3) is
653 // then empty.
655 // - Otherwise, (1) only contains uses in the same extended basic block
656 // as the definition, and it is terminated by a use that marks the end
657 // of the live range for the EBB. In other words, if the resource dies
658 // in the EBB, the last use by a nondebug instruction marks the point at
659 // which it dies, otherwise there is a fake live-out use at the end of
660 // the EBB.
662 // Since debug instructions should not affect codegen, they opportunisticly
663 // attach to the same set_info as nondebug instructions where possible.
664 // If a nondebug instruction would attach to a degenerate phi and if no
665 // such phi exists, debug instructions instead attach to whichever set_info
666 // provides the value, regardless of where that set_info is.
667 class set_info : public def_info
669 // Overall size: 6 LP64 words.
670 friend class function_info;
671 using use_splay_tree = splay_tree<use_info *>;
673 public:
674 // Return the first and last uses of the set, or null if the list is empty.
675 // See the comment above for details about the order.
676 use_info *first_use () const { return m_first_use; }
677 use_info *last_use () const;
679 // Return the first and last uses of the set by nondebug instructions,
680 // or null if there are no such uses. The uses are in reverse postorder.
681 use_info *first_nondebug_insn_use () const;
682 use_info *last_nondebug_insn_use () const;
684 // Return the first use of the set by any kind of instruction, or null
685 // if there are no such uses. The uses are in the order described above.
686 use_info *first_any_insn_use () const;
688 // Return the last use of the set by phi inputs, or null if there are no
689 // such uses. The phi input uses are in no particular order.
690 use_info *last_phi_use () const;
692 // Return true if at least one nondebug instruction or phi node uses
693 // the set's result. This is equivalent to testing whether the set is
694 // ever live.
695 bool has_nondebug_uses () const;
697 // Return true if anything uses the set's result. Note that this includes
698 // uses by debug instructions, so it should not be used for optimization
699 // decisions.
700 bool has_any_uses () const { return m_first_use; }
702 // Return true if at least one nondebug instruction uses the set's result.
703 bool has_nondebug_insn_uses () const;
705 // Return true if at least one phi node uses the set's result.
706 bool has_phi_uses () const;
708 // If there is exactly one nondebug use of the set's result, return that use,
709 // otherwise return null. The use might be in an instruction or in a phi
710 // node.
711 use_info *single_nondebug_use () const;
713 // If exactly one nondebug instruction uses the set's result, return the use
714 // by that instruction, otherwise return null.
715 use_info *single_nondebug_insn_use () const;
717 // If exactly one phi node uses the set's result, return the use by that phi
718 // node, otherwise return null.
719 use_info *single_phi_use () const;
721 // Return true if the set and its uses are contained within a single
722 // extended basic block, with the set coming first. This implies
723 // that all uses are by instructions rather than phi nodes.
724 bool is_local_to_ebb () const;
726 // List all the uses of the set, in the order described above.
727 iterator_range<use_iterator> all_uses () const;
729 // Return uses () in reverse order.
730 iterator_range<reverse_use_iterator> reverse_all_uses () const;
732 // List the uses of the set by nondebug instructions, in reverse postorder.
733 iterator_range<nondebug_insn_use_iterator> nondebug_insn_uses () const;
735 // Return nondebug_insn_uses () in reverse order.
736 iterator_range<reverse_use_iterator> reverse_nondebug_insn_uses () const;
738 // List the uses of the set by any kind of instruction. The list follows
739 // the order described above.
740 iterator_range<any_insn_use_iterator> all_insn_uses () const;
742 // List the uses of the set by phi nodes, in no particular order.
743 // There is therefore no reversed equivalent of this list.
744 iterator_range<phi_use_iterator> phi_uses () const;
746 // Print a description of the set to PP under the control of
747 // PP_ACCESS_* flags FLAGS.
748 void print (pretty_printer *pp,
749 unsigned int flags = PP_ACCESS_DEFAULT) const;
751 protected:
752 set_info (insn_info *, resource_info, access_kind);
754 // Print information about uses () to PP, continuing information printed
755 // about the set itself.
756 void print_uses_on_new_lines (pretty_printer *pp) const;
758 private:
759 // Sets (including phis) account for about 94% of all definitions
761 set_info (insn_info *, resource_info);
763 void set_first_use (use_info *);
765 // The first use in the list.
766 use_info *m_first_use;
768 // The root of a splay tree of all uses, built lazily when we first
769 // think it's needed.
770 use_splay_tree m_use_tree;
773 // A set_info for an on-the-side phi node. The phi node is attached
774 // to an extended basic block EBB and has one input for each incoming edge.
775 // The inputs are represented as an array of use_infos, with input I
776 // corresponding to EDGE_PRED (EBB->first_bb ()->cfg_bb (), I).
778 // Each phi node has a densely-allocated unique identifier, which is intended
779 // to be suitable for bitmaps or sbitmaps.
781 // All the phi nodes in an extended basic block are chained together
782 // into a linked list. The list has no particular order.
783 class phi_info : public set_info
785 // Overall size: 8 LP64 words
786 friend class function_info;
788 public:
789 // Return the previous and next phi nodes in the extended basic block's list,
790 // or null if none.
791 phi_info *prev_phi () const { return m_prev_phi; }
792 phi_info *next_phi () const { return m_next_phi; }
794 // Return the number of phi inputs. This is 1 for degenerate phis,
795 // otherwise it is equal to the number of incoming edges.
796 unsigned int num_inputs () const { return m_num_inputs; }
798 // Return true if the phi node is degenerate, i.e. if it has only a
799 // single input.
800 bool is_degenerate () const { return m_num_inputs == 1; }
802 // Return the phi node's unique identifier.
803 unsigned int uid () const { return m_uid; }
805 // Return the array of inputs. For degenerate phi nodes, this array contains
806 // a single element, otherwise it has one input per incoming edge,
807 // with element E corresponding to incoming edge E.
808 use_array inputs () const;
810 // Return the use_info that describes the phi input for incoming edge E.
811 use_info *input_use (unsigned int e) const;
813 // Return the value of resource () on incoming edge E, or null if the
814 // value is completely undefined for that edge.
815 set_info *input_value (unsigned int e) const;
817 // Print a description of the phi node to PP under the control of
818 // PP_ACCESS_* flags FLAGS.
819 void print (pretty_printer *pp,
820 unsigned int flags = PP_ACCESS_DEFAULT) const;
822 private:
823 phi_info (insn_info *insn, resource_info resource, unsigned int uid);
825 void make_degenerate (use_info *);
826 void set_inputs (use_array inputs);
827 void set_prev_phi (phi_info *prev_phi) { m_prev_phi = prev_phi; }
828 void set_next_phi (phi_info *next_phi) { m_next_phi = next_phi; }
829 void clear_phi_links () { m_prev_phi = m_next_phi = nullptr; }
830 bool has_phi_links () { return m_prev_phi || m_next_phi; }
832 // The values returned by the accessors above.
833 unsigned int m_uid;
834 unsigned int m_num_inputs;
835 union
837 access_info *const *m_inputs;
838 access_info *m_single_input;
840 phi_info *m_prev_phi;
841 phi_info *m_next_phi;
844 // An iterator for lists of phi nodes.
845 using phi_iterator = list_iterator<phi_info, &phi_info::next_phi>;
847 // One node in a splay tree of definitions. This base class represents
848 // a single def_info, but it is structured to allow derived classes
849 // to add a range.
850 class def_node
852 // Size: 3 LP64 words.
853 friend class function_info;
854 friend class default_splay_tree_accessors<def_node *>;
856 public:
857 // Return the first definition that the node represents.
858 def_info *first_def () const;
860 // Return which type of access first_def () is.
861 bool contains_clobber () const { return m_clobber_or_set.is_first (); }
862 bool contains_set () const { return m_clobber_or_set.is_second (); }
864 protected:
865 // More nodes are clobbers rather than sets, so put clobbers first.
866 // Neither choice can be null.
867 using clobber_or_set = pointer_mux<clobber_info, set_info>;
869 // Construct a node that represents FIRST_DEF (and possibly later
870 // definitions too, if called from a derived class).
871 def_node (clobber_or_set first_def);
873 // The first definition in the node.
874 clobber_or_set m_clobber_or_set;
876 private:
877 // The splay tree child nodes.
878 def_node *m_children[2];
881 // One node in a splay tree of def_infos, representing a single set_info.
882 class set_node : public def_node
884 // Overall size: 3 LP64 words.
885 friend class function_info;
887 public:
888 // Return the set that the node contains.
889 set_info *set () const { return m_clobber_or_set.known_second (); }
891 // Print a description of the node to PP.
892 void print (pretty_printer *pp) const;
894 private:
895 // Construct a node for SET.
896 set_node (set_info *set) : def_node (set) {}
899 // One node in a splay tree of def_infos. This class represents
900 // a list of contiguous clobber_infos, in execution order.
901 class clobber_group : public def_node
903 // Overall size: 5 LP64 words.
904 friend class function_info;
906 public:
907 // Return the first and last clobbers in the group. The results are
908 // always nonnull.
909 clobber_info *first_clobber () const;
910 clobber_info *last_clobber () const { return m_last_clobber; }
912 // Return true if this group has been replaced by new clobber_groups.
913 bool has_been_superceded () const { return !m_last_clobber; }
915 // Return a list of the clobbers in the group, in execution order.
916 iterator_range<def_iterator> clobbers () const;
918 // Print a description of the group to PP.
919 void print (pretty_printer *pp) const;
921 private:
922 clobber_group (clobber_info *clobber);
924 // Set the values of first_clobber () and last_clobber ().
925 void set_first_clobber (clobber_info *c) { m_clobber_or_set = c; }
926 void set_last_clobber (clobber_info *c) { m_last_clobber = c; }
928 // The value returned by last_clobber ().
929 clobber_info *m_last_clobber;
931 // A splay tree that contains all the clobbers in the group.
932 // The root of the splay tree always has an up-to-date group
933 // pointer, but the other clobbers in the tree might not.
934 clobber_tree m_clobber_tree;
937 // A splay tree in which one node represents a standalone set_info or a
938 // range of consecutive clobber_infos. The nodes follow execution order
939 // and maintain the invariant that no two groups of clobber_infos appear
940 // next to each other (instead, the groups are merged).
941 using def_splay_tree = default_splay_tree<def_node *>;
943 // This type represents a choice between:
945 // (1) a single definition of a resource
946 // (2) a node in a def_splay_tree that represents either a single
947 // set or a group of clobbers.
948 class def_mux : public pointer_mux<def_info, def_node>
950 using parent = pointer_mux<def_info, def_node>;
952 // Provide the same constructors as the pointer_mux.
953 using parent::parent;
955 public:
956 // Return the first definition associated with this mux. If the mux holds
957 // a single definition, the result is that definition. If the mux holds
958 // a clobber_group, the result is the first clobber in the group.
959 def_info *first_def () const;
961 // Return the last definition associated with this mux. If the mux holds
962 // a single definition, the result is that definition. If the mux holds
963 // a clobber_group, the result is the last clobber in the group.
964 def_info *last_def () const;
966 // If the pointer represents a set_info, return that set_info,
967 // otherwise return null.
968 set_info *set () const;
971 // This class represents the result of looking up the definition of a
972 // resource at a particular point, here referred to as point P.
973 // There are four states:
975 // - MUX is null if there were no definitions to search.
977 // - Otherwise, COMPARISON is 0 if we found a definition at P or a
978 // clobber_group that spans P. MUX then contains this definition
979 // or clobber_group.
981 // - Otherwise, COMPARISON is greater than 0 if we found the definition
982 // that precedes P or the group of clobbers that precedes P. MUX then
983 // contains this definition or clobber_group.
985 // - Otherwise, COMPARISON is less than zero and we found the definition
986 // that follows P, or the group of clobbers that follows P. MUX then
987 // contains this definition or clobber_group.
988 class def_lookup
990 public:
991 // If we found a clobber_group that spans P, return the definition
992 // that precedes the start of the group, or null if none.
994 // Otherwise, return the last definition that occurs before P,
995 // or null if none.
996 def_info *prev_def () const;
998 // If we found a clobber_group that spans P, return the definition
999 // that follows the end of the group, or null if none.
1001 // Otherwise, return the first definition that occurs after P,
1002 // or null if none.
1003 def_info *next_def () const;
1005 // If we found a set_info at P, return that set_info, otherwise return null.
1006 set_info *matching_set () const;
1008 // If we found a set_info at P, return that set_info, otherwise return
1009 // prev_def ().
1010 def_info *matching_or_prev_def () const;
1012 // If we found a set_info at P, return that set_info, otherwise return
1013 // next_def ().
1014 def_info *matching_or_next_def () const;
1016 def_mux mux;
1017 int comparison;
1020 void pp_resource (pretty_printer *, resource_info);
1021 void pp_access (pretty_printer *, const access_info *,
1022 unsigned int flags = PP_ACCESS_DEFAULT);
1023 void pp_accesses (pretty_printer *, access_array,
1024 unsigned int flags = PP_ACCESS_DEFAULT);
1025 void pp_def_node (pretty_printer *, const def_node *);
1026 void pp_def_mux (pretty_printer *, def_mux);
1027 void pp_def_lookup (pretty_printer *, def_lookup);
1031 void dump (FILE *, rtl_ssa::resource_info);
1032 void dump (FILE *, const rtl_ssa::access_info *,
1033 unsigned int flags = rtl_ssa::PP_ACCESS_DEFAULT);
1034 void dump (FILE *, rtl_ssa::access_array,
1035 unsigned int flags = rtl_ssa::PP_ACCESS_DEFAULT);
1036 void dump (FILE *, const rtl_ssa::def_node *);
1037 void dump (FILE *, rtl_ssa::def_mux);
1038 void dump (FILE *, rtl_ssa::def_lookup);
1040 void DEBUG_FUNCTION debug (const rtl_ssa::resource_info *);
1041 void DEBUG_FUNCTION debug (const rtl_ssa::access_info *);
1042 void DEBUG_FUNCTION debug (const rtl_ssa::access_array);
1043 void DEBUG_FUNCTION debug (const rtl_ssa::def_node *);
1044 void DEBUG_FUNCTION debug (const rtl_ssa::def_mux &);
1045 void DEBUG_FUNCTION debug (const rtl_ssa::def_lookup &);