1//===- RegionInfo.h - SESE region analysis ----------------------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// Calculate a program structure tree built out of single entry single exit
10// regions.
11// The basic ideas are taken from "The Program Structure Tree - Richard Johnson,
12// David Pearson, Keshav Pingali - 1994", however enriched with ideas from "The
13// Refined Process Structure Tree - Jussi Vanhatalo, Hagen Voelyer, Jana
14// Koehler - 2009".
15// The algorithm to calculate these data structures however is completely
16// different, as it takes advantage of existing information already available
17// in (Post)dominace tree and dominance frontier passes. This leads to a simpler
18// and in practice hopefully better performing algorithm. The runtime of the
19// algorithms described in the papers above are both linear in graph size,
20// O(V+E), whereas this algorithm is not, as the dominance frontier information
21// itself is not, but in practice runtime seems to be in the order of magnitude
22// of dominance tree calculation.
23//
24// WARNING: LLVM is generally very concerned about compile time such that
25// the use of additional analysis passes in the default
26// optimization sequence is avoided as much as possible.
27// Specifically, if you do not need the RegionInfo, but dominance
28// information could be sufficient please base your work only on
29// the dominator tree. Most passes maintain it, such that using
30// it has often near zero cost. In contrast RegionInfo is by
31// default not available, is not maintained by existing
32// transformations and there is no intention to do so.
33//
34//===----------------------------------------------------------------------===//
35
36#ifndef LLVM_ANALYSIS_REGIONINFO_H
37#define LLVM_ANALYSIS_REGIONINFO_H
38
39#include "llvm/ADT/DenseMap.h"
40#include "llvm/ADT/DepthFirstIterator.h"
41#include "llvm/ADT/GraphTraits.h"
42#include "llvm/ADT/PointerIntPair.h"
43#include "llvm/ADT/iterator_range.h"
44#include "llvm/IR/Dominators.h"
45#include "llvm/IR/PassManager.h"
46#include "llvm/Pass.h"
47#include <algorithm>
48#include <cassert>
49#include <map>
50#include <memory>
51#include <set>
52#include <string>
53#include <type_traits>
54#include <vector>
55
56namespace llvm {
57
58class DominanceFrontier;
59class Loop;
60class LoopInfo;
61class PostDominatorTree;
62class Region;
63template <class RegionTr> class RegionBase;
64class RegionInfo;
65template <class RegionTr> class RegionInfoBase;
66class RegionNode;
67class raw_ostream;
68
69// Class to be specialized for different users of RegionInfo
70// (i.e. BasicBlocks or MachineBasicBlocks). This is only to avoid needing to
71// pass around an unreasonable number of template parameters.
72template <class FuncT_>
73struct RegionTraits {
74 // FuncT
75 // BlockT
76 // RegionT
77 // RegionNodeT
78 // RegionInfoT
79 using BrokenT = typename FuncT_::UnknownRegionTypeError;
80};
81
82template <>
83struct RegionTraits<Function> {
84 using FuncT = Function;
85 using BlockT = BasicBlock;
86 using RegionT = Region;
87 using RegionNodeT = RegionNode;
88 using RegionInfoT = RegionInfo;
89 using DomTreeT = DominatorTree;
90 using DomTreeNodeT = DomTreeNode;
91 using DomFrontierT = DominanceFrontier;
92 using PostDomTreeT = PostDominatorTree;
93 using InstT = Instruction;
94 using LoopT = Loop;
95 using LoopInfoT = LoopInfo;
96
97 static unsigned getNumSuccessors(BasicBlock *BB) {
98 return BB->getTerminator()->getNumSuccessors();
99 }
100
101 /// Update statistics about created regions.
102 LLVM_ABI static void updateStatistics(Region *R);
103};
104
105/// Marker class to iterate over the elements of a Region in flat mode.
106///
107/// The class is used to either iterate in Flat mode or by not using it to not
108/// iterate in Flat mode. During a Flat mode iteration all Regions are entered
109/// and the iteration returns every BasicBlock. If the Flat mode is not
110/// selected for SubRegions just one RegionNode containing the subregion is
111/// returned.
112template <class GraphType>
113class FlatIt {};
114
115/// A RegionNode represents a subregion or a BasicBlock that is part of a
116/// Region.
117template <class Tr>
118class RegionNodeBase {
119 friend class RegionBase<Tr>;
120
121public:
122 using BlockT = typename Tr::BlockT;
123 using RegionT = typename Tr::RegionT;
124
125private:
126 /// This is the entry basic block that starts this region node. If this is a
127 /// BasicBlock RegionNode, then entry is just the basic block, that this
128 /// RegionNode represents. Otherwise it is the entry of this (Sub)RegionNode.
129 ///
130 /// In the BBtoRegionNode map of the parent of this node, BB will always map
131 /// to this node no matter which kind of node this one is.
132 ///
133 /// The node can hold either a Region or a BasicBlock.
134 /// Use one bit to save, if this RegionNode is a subregion or BasicBlock
135 /// RegionNode.
136 PointerIntPair<BlockT *, 1, bool> entry;
137
138 /// The parent Region of this RegionNode.
139 /// @see getParent()
140 RegionT *parent;
141
142protected:
143 /// Create a RegionNode.
144 ///
145 /// @param Parent The parent of this RegionNode.
146 /// @param Entry The entry BasicBlock of the RegionNode. If this
147 /// RegionNode represents a BasicBlock, this is the
148 /// BasicBlock itself. If it represents a subregion, this
149 /// is the entry BasicBlock of the subregion.
150 /// @param isSubRegion If this RegionNode represents a SubRegion.
151 inline RegionNodeBase(RegionT *Parent, BlockT *Entry,
152 bool isSubRegion = false)
153 : entry(Entry, isSubRegion), parent(Parent) {}
154
155public:
156 RegionNodeBase(const RegionNodeBase &) = delete;
157 RegionNodeBase &operator=(const RegionNodeBase &) = delete;
158
159 /// Get the parent Region of this RegionNode.
160 ///
161 /// The parent Region is the Region this RegionNode belongs to. If for
162 /// example a BasicBlock is element of two Regions, there exist two
163 /// RegionNodes for this BasicBlock. Each with the getParent() function
164 /// pointing to the Region this RegionNode belongs to.
165 ///
166 /// @return Get the parent Region of this RegionNode.
167 inline RegionT *getParent() const { return parent; }
168
169 /// Get the entry BasicBlock of this RegionNode.
170 ///
171 /// If this RegionNode represents a BasicBlock this is just the BasicBlock
172 /// itself, otherwise we return the entry BasicBlock of the Subregion
173 ///
174 /// @return The entry BasicBlock of this RegionNode.
175 inline BlockT *getEntry() const { return entry.getPointer(); }
176
177 /// Get the content of this RegionNode.
178 ///
179 /// This can be either a BasicBlock or a subregion. Before calling getNodeAs()
180 /// check the type of the content with the isSubRegion() function call.
181 ///
182 /// @return The content of this RegionNode.
183 template <class T> inline T *getNodeAs() const;
184
185 /// Is this RegionNode a subregion?
186 ///
187 /// @return True if it contains a subregion. False if it contains a
188 /// BasicBlock.
189 inline bool isSubRegion() const { return entry.getInt(); }
190};
191
192//===----------------------------------------------------------------------===//
193/// A single entry single exit Region.
194///
195/// A Region is a connected subgraph of a control flow graph that has exactly
196/// two connections to the remaining graph. It can be used to analyze or
197/// optimize parts of the control flow graph.
198///
199/// A <em> simple Region </em> is connected to the remaining graph by just two
200/// edges. One edge entering the Region and another one leaving the Region.
201///
202/// An <em> extended Region </em> (or just Region) is a subgraph that can be
203/// transform into a simple Region. The transformation is done by adding
204/// BasicBlocks that merge several entry or exit edges so that after the merge
205/// just one entry and one exit edge exists.
206///
207/// The \e Entry of a Region is the first BasicBlock that is passed after
208/// entering the Region. It is an element of the Region. The entry BasicBlock
209/// dominates all BasicBlocks in the Region.
210///
211/// The \e Exit of a Region is the first BasicBlock that is passed after
212/// leaving the Region. It is not an element of the Region. The exit BasicBlock,
213/// postdominates all BasicBlocks in the Region.
214///
215/// A <em> canonical Region </em> cannot be constructed by combining smaller
216/// Regions.
217///
218/// Region A is the \e parent of Region B, if B is completely contained in A.
219///
220/// Two canonical Regions either do not intersect at all or one is
221/// the parent of the other.
222///
223/// The <em> Program Structure Tree</em> is a graph (V, E) where V is the set of
224/// Regions in the control flow graph and E is the \e parent relation of these
225/// Regions.
226///
227/// Example:
228///
229/// \verbatim
230/// A simple control flow graph, that contains two regions.
231///
232/// 1
233/// / |
234/// 2 |
235/// / \ 3
236/// 4 5 |
237/// | | |
238/// 6 7 8
239/// \ | /
240/// \ |/ Region A: 1 -> 9 {1,2,3,4,5,6,7,8}
241/// 9 Region B: 2 -> 9 {2,4,5,6,7}
242/// \endverbatim
243///
244/// You can obtain more examples by either calling
245///
246/// <tt> "opt -passes='print<regions>' anyprogram.ll" </tt>
247/// or
248/// <tt> "opt -view-regions-only anyprogram.ll" </tt>
249///
250/// on any LLVM file you are interested in.
251///
252/// The first call returns a textual representation of the program structure
253/// tree, the second one creates a graphical representation using graphviz.
254template <class Tr>
255class RegionBase : public RegionNodeBase<Tr> {
256 friend class RegionInfoBase<Tr>;
257
258 using FuncT = typename Tr::FuncT;
259 using BlockT = typename Tr::BlockT;
260 using RegionInfoT = typename Tr::RegionInfoT;
261 using RegionT = typename Tr::RegionT;
262 using RegionNodeT = typename Tr::RegionNodeT;
263 using DomTreeT = typename Tr::DomTreeT;
264 using LoopT = typename Tr::LoopT;
265 using LoopInfoT = typename Tr::LoopInfoT;
266 using InstT = typename Tr::InstT;
267
268 using BlockTraits = GraphTraits<BlockT *>;
269 using InvBlockTraits = GraphTraits<Inverse<BlockT *>>;
270 using SuccIterTy = typename BlockTraits::ChildIteratorType;
271 using PredIterTy = typename InvBlockTraits::ChildIteratorType;
272
273 // Information necessary to manage this Region.
274 RegionInfoT *RI;
275 DomTreeT *DT;
276
277 // The exit BasicBlock of this region.
278 // (The entry BasicBlock is part of RegionNode)
279 BlockT *exit;
280
281 using RegionSet = std::vector<std::unique_ptr<RegionT>>;
282
283 // The subregions of this region.
284 RegionSet children;
285
286 using BBNodeMapT = std::map<BlockT *, std::unique_ptr<RegionNodeT>>;
287
288 // Save the BasicBlock RegionNodes that are element of this Region.
289 mutable BBNodeMapT BBNodeMap;
290
291 /// Check if a BB is in this Region. This check also works
292 /// if the region is incorrectly built. (EXPENSIVE!)
293 void verifyBBInRegion(BlockT *BB) const;
294
295 /// Walk over all the BBs of the region starting from BB and
296 /// verify that all reachable basic blocks are elements of the region.
297 /// (EXPENSIVE!)
298 void verifyWalk(BlockT *BB, std::set<BlockT *> *visitedBB) const;
299
300 /// Verify if the region and its children are valid regions (EXPENSIVE!)
301 void verifyRegionNest() const;
302
303public:
304 /// Create a new region.
305 ///
306 /// @param Entry The entry basic block of the region.
307 /// @param Exit The exit basic block of the region.
308 /// @param RI The region info object that is managing this region.
309 /// @param DT The dominator tree of the current function.
310 /// @param Parent The surrounding region or NULL if this is a top level
311 /// region.
312 RegionBase(BlockT *Entry, BlockT *Exit, RegionInfoT *RI, DomTreeT *DT,
313 RegionT *Parent = nullptr);
314
315 RegionBase(const RegionBase &) = delete;
316 RegionBase &operator=(const RegionBase &) = delete;
317
318 /// Delete the Region and all its subregions.
319 ~RegionBase();
320
321 /// Get the entry BasicBlock of the Region.
322 /// @return The entry BasicBlock of the region.
323 BlockT *getEntry() const {
324 return RegionNodeBase<Tr>::getEntry();
325 }
326
327 /// Replace the entry basic block of the region with the new basic
328 /// block.
329 ///
330 /// @param BB The new entry basic block of the region.
331 void replaceEntry(BlockT *BB);
332
333 /// Replace the exit basic block of the region with the new basic
334 /// block.
335 ///
336 /// @param BB The new exit basic block of the region.
337 void replaceExit(BlockT *BB);
338
339 /// Recursively replace the entry basic block of the region.
340 ///
341 /// This function replaces the entry basic block with a new basic block. It
342 /// also updates all child regions that have the same entry basic block as
343 /// this region.
344 ///
345 /// @param NewEntry The new entry basic block.
346 void replaceEntryRecursive(BlockT *NewEntry);
347
348 /// Recursively replace the exit basic block of the region.
349 ///
350 /// This function replaces the exit basic block with a new basic block. It
351 /// also updates all child regions that have the same exit basic block as
352 /// this region.
353 ///
354 /// @param NewExit The new exit basic block.
355 void replaceExitRecursive(BlockT *NewExit);
356
357 /// Get the exit BasicBlock of the Region.
358 /// @return The exit BasicBlock of the Region, NULL if this is the TopLevel
359 /// Region.
360 BlockT *getExit() const { return exit; }
361
362 /// Get the parent of the Region.
363 /// @return The parent of the Region or NULL if this is a top level
364 /// Region.
365 RegionT *getParent() const {
366 return RegionNodeBase<Tr>::getParent();
367 }
368
369 /// Get the RegionNode representing the current Region.
370 /// @return The RegionNode representing the current Region.
371 RegionNodeT *getNode() const {
372 return const_cast<RegionNodeT *>(
373 reinterpret_cast<const RegionNodeT *>(this));
374 }
375
376 /// Get the nesting level of this Region.
377 ///
378 /// An toplevel Region has depth 0.
379 ///
380 /// @return The depth of the region.
381 unsigned getDepth() const;
382
383 /// Check if a Region is the TopLevel region.
384 ///
385 /// The toplevel region represents the whole function.
386 bool isTopLevelRegion() const { return exit == nullptr; }
387
388 /// Return a new (non-canonical) region, that is obtained by joining
389 /// this region with its predecessors.
390 ///
391 /// @return A region also starting at getEntry(), but reaching to the next
392 /// basic block that forms with getEntry() a (non-canonical) region.
393 /// NULL if such a basic block does not exist.
394 RegionT *getExpandedRegion() const;
395
396 /// Return the first block of this region's single entry edge,
397 /// if existing.
398 ///
399 /// @return The BasicBlock starting this region's single entry edge,
400 /// else NULL.
401 BlockT *getEnteringBlock() const;
402
403 /// Return the first block of this region's single exit edge,
404 /// if existing.
405 ///
406 /// @return The BasicBlock starting this region's single exit edge,
407 /// else NULL.
408 BlockT *getExitingBlock() const;
409
410 /// Collect all blocks of this region's single exit edge, if existing.
411 ///
412 /// @return True if this region contains all the predecessors of the exit.
413 bool getExitingBlocks(SmallVectorImpl<BlockT *> &Exitings) const;
414
415 /// Is this a simple region?
416 ///
417 /// A region is simple if it has exactly one exit and one entry edge.
418 ///
419 /// @return True if the Region is simple.
420 bool isSimple() const;
421
422 /// Returns the name of the Region.
423 /// @return The Name of the Region.
424 std::string getNameStr() const;
425
426 /// Return the RegionInfo object, that belongs to this Region.
427 RegionInfoT *getRegionInfo() const { return RI; }
428
429 /// PrintStyle - Print region in difference ways.
430 enum PrintStyle { PrintNone, PrintBB, PrintRN };
431
432 /// Print the region.
433 ///
434 /// @param OS The output stream the Region is printed to.
435 /// @param printTree Print also the tree of subregions.
436 /// @param level The indentation level used for printing.
437 void print(raw_ostream &OS, bool printTree = true, unsigned level = 0,
438 PrintStyle Style = PrintNone) const;
439
440#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
441 /// Print the region to stderr.
442 void dump() const;
443#endif
444
445 /// Check if the region contains a BasicBlock.
446 ///
447 /// @param BB The BasicBlock that might be contained in this Region.
448 /// @return True if the block is contained in the region otherwise false.
449 bool contains(const BlockT *BB) const;
450
451 /// Check if the region contains another region.
452 ///
453 /// @param SubRegion The region that might be contained in this Region.
454 /// @return True if SubRegion is contained in the region otherwise false.
455 bool contains(const RegionT *SubRegion) const {
456 // Toplevel Region.
457 if (!getExit())
458 return true;
459
460 return contains(SubRegion->getEntry()) &&
461 (contains(SubRegion->getExit()) ||
462 SubRegion->getExit() == getExit());
463 }
464
465 /// Check if the region contains an Instruction.
466 ///
467 /// @param Inst The Instruction that might be contained in this region.
468 /// @return True if the Instruction is contained in the region otherwise
469 /// false.
470 bool contains(const InstT *Inst) const { return contains(Inst->getParent()); }
471
472 /// Check if the region contains a loop.
473 ///
474 /// @param L The loop that might be contained in this region.
475 /// @return True if the loop is contained in the region otherwise false.
476 /// In case a NULL pointer is passed to this function the result
477 /// is false, except for the region that describes the whole function.
478 /// In that case true is returned.
479 bool contains(const LoopT *L) const;
480
481 /// Get the outermost loop in the region that contains a loop.
482 ///
483 /// Find for a Loop L the outermost loop OuterL that is a parent loop of L
484 /// and is itself contained in the region.
485 ///
486 /// @param L The loop the lookup is started.
487 /// @return The outermost loop in the region, NULL if such a loop does not
488 /// exist or if the region describes the whole function.
489 LoopT *outermostLoopInRegion(LoopT *L) const;
490
491 /// Get the outermost loop in the region that contains a basic block.
492 ///
493 /// Find for a basic block BB the outermost loop L that contains BB and is
494 /// itself contained in the region.
495 ///
496 /// @param LI A pointer to a LoopInfo analysis.
497 /// @param BB The basic block surrounded by the loop.
498 /// @return The outermost loop in the region, NULL if such a loop does not
499 /// exist or if the region describes the whole function.
500 LoopT *outermostLoopInRegion(LoopInfoT *LI, BlockT *BB) const;
501
502 /// Get the subregion that starts at a BasicBlock
503 ///
504 /// @param BB The BasicBlock the subregion should start.
505 /// @return The Subregion if available, otherwise NULL.
506 RegionT *getSubRegionNode(BlockT *BB) const;
507
508 /// Get the RegionNode for a BasicBlock
509 ///
510 /// @param BB The BasicBlock at which the RegionNode should start.
511 /// @return If available, the RegionNode that represents the subregion
512 /// starting at BB. If no subregion starts at BB, the RegionNode
513 /// representing BB.
514 RegionNodeT *getNode(BlockT *BB) const;
515
516 /// Get the BasicBlock RegionNode for a BasicBlock
517 ///
518 /// @param BB The BasicBlock for which the RegionNode is requested.
519 /// @return The RegionNode representing the BB.
520 RegionNodeT *getBBNode(BlockT *BB) const;
521
522 /// Add a new subregion to this Region.
523 ///
524 /// @param SubRegion The new subregion that will be added.
525 /// @param moveChildren Move the children of this region, that are also
526 /// contained in SubRegion into SubRegion.
527 void addSubRegion(RegionT *SubRegion, bool moveChildren = false);
528
529 /// Remove a subregion from this Region.
530 ///
531 /// The subregion is not deleted, as it will probably be inserted into another
532 /// region.
533 /// @param SubRegion The SubRegion that will be removed.
534 RegionT *removeSubRegion(RegionT *SubRegion);
535
536 /// Move all direct child nodes of this Region to another Region.
537 ///
538 /// @param To The Region the child nodes will be transferred to.
539 void transferChildrenTo(RegionT *To);
540
541 /// Verify if the region is a correct region.
542 ///
543 /// Check if this is a correctly build Region. This is an expensive check, as
544 /// the complete CFG of the Region will be walked.
545 void verifyRegion() const;
546
547 /// Clear the cache for BB RegionNodes.
548 ///
549 /// After calling this function the BasicBlock RegionNodes will be stored at
550 /// different memory locations. RegionNodes obtained before this function is
551 /// called are therefore not comparable to RegionNodes abtained afterwords.
552 void clearNodeCache();
553
554 /// @name Subregion Iterators
555 ///
556 /// These iterators iterator over all subregions of this Region.
557 //@{
558 using iterator = typename RegionSet::iterator;
559 using const_iterator = typename RegionSet::const_iterator;
560
561 iterator begin() { return children.begin(); }
562 iterator end() { return children.end(); }
563
564 const_iterator begin() const { return children.begin(); }
565 const_iterator end() const { return children.end(); }
566 //@}
567
568 /// @name BasicBlock Iterators
569 ///
570 /// These iterators iterate over all BasicBlocks that are contained in this
571 /// Region. The iterator also iterates over BasicBlocks that are elements of
572 /// a subregion of this Region. It is therefore called a flat iterator.
573 //@{
574 template <bool IsConst>
575 class block_iterator_wrapper
576 : public df_iterator<
577 std::conditional_t<IsConst, const BlockT, BlockT> *> {
578 using super =
579 df_iterator<std::conditional_t<IsConst, const BlockT, BlockT> *>;
580
581 public:
582 using Self = block_iterator_wrapper<IsConst>;
583 using value_type = typename super::value_type;
584
585 // Construct the begin iterator.
586 block_iterator_wrapper(value_type Entry, value_type Exit)
587 : super(df_begin(Entry)) {
588 // Mark the exit of the region as visited, so that the children of the
589 // exit and the exit itself, i.e. the block outside the region will never
590 // be visited.
591 super::Visited.insert(Exit);
592 }
593
594 // Construct the end iterator.
595 block_iterator_wrapper() : super(df_end<value_type>((BlockT *)nullptr)) {}
596
597 /*implicit*/ block_iterator_wrapper(super I) : super(I) {}
598
599 // FIXME: Even a const_iterator returns a non-const BasicBlock pointer.
600 // This was introduced for backwards compatibility, but should
601 // be removed as soon as all users are fixed.
602 BlockT *operator*() const {
603 return const_cast<BlockT *>(super::operator*());
604 }
605 };
606
607 using block_iterator = block_iterator_wrapper<false>;
608 using const_block_iterator = block_iterator_wrapper<true>;
609
610 block_iterator block_begin() { return block_iterator(getEntry(), getExit()); }
611
612 block_iterator block_end() { return block_iterator(); }
613
614 const_block_iterator block_begin() const {
615 return const_block_iterator(getEntry(), getExit());
616 }
617 const_block_iterator block_end() const { return const_block_iterator(); }
618
619 using block_range = iterator_range<block_iterator>;
620 using const_block_range = iterator_range<const_block_iterator>;
621
622 /// Returns a range view of the basic blocks in the region.
623 inline block_range blocks() {
624 return block_range(block_begin(), block_end());
625 }
626
627 /// Returns a range view of the basic blocks in the region.
628 ///
629 /// This is the 'const' version of the range view.
630 inline const_block_range blocks() const {
631 return const_block_range(block_begin(), block_end());
632 }
633 //@}
634
635 /// @name Element Iterators
636 ///
637 /// These iterators iterate over all BasicBlock and subregion RegionNodes that
638 /// are direct children of this Region. It does not iterate over any
639 /// RegionNodes that are also element of a subregion of this Region.
640 //@{
641 using element_iterator =
642 df_iterator<RegionNodeT *, df_iterator_default_set<RegionNodeT *>, false,
643 GraphTraits<RegionNodeT *>>;
644
645 using const_element_iterator =
646 df_iterator<const RegionNodeT *,
647 df_iterator_default_set<const RegionNodeT *>, false,
648 GraphTraits<const RegionNodeT *>>;
649
650 element_iterator element_begin();
651 element_iterator element_end();
652 iterator_range<element_iterator> elements() {
653 return make_range(element_begin(), element_end());
654 }
655
656 const_element_iterator element_begin() const;
657 const_element_iterator element_end() const;
658 iterator_range<const_element_iterator> elements() const {
659 return make_range(element_begin(), element_end());
660 }
661 //@}
662};
663
664/// Print a RegionNode.
665template <class Tr>
666inline raw_ostream &operator<<(raw_ostream &OS, const RegionNodeBase<Tr> &Node);
667
668//===----------------------------------------------------------------------===//
669/// Analysis that detects all canonical Regions.
670///
671/// The RegionInfo pass detects all canonical regions in a function. The Regions
672/// are connected using the parent relation. This builds a Program Structure
673/// Tree.
674template <class Tr>
675class RegionInfoBase {
676 friend class RegionInfo;
677 friend class MachineRegionInfo;
678
679 using BlockT = typename Tr::BlockT;
680 using FuncT = typename Tr::FuncT;
681 using RegionT = typename Tr::RegionT;
682 using RegionInfoT = typename Tr::RegionInfoT;
683 using DomTreeT = typename Tr::DomTreeT;
684 using DomTreeNodeT = typename Tr::DomTreeNodeT;
685 using PostDomTreeT = typename Tr::PostDomTreeT;
686 using DomFrontierT = typename Tr::DomFrontierT;
687 using BlockTraits = GraphTraits<BlockT *>;
688 using InvBlockTraits = GraphTraits<Inverse<BlockT *>>;
689 using SuccIterTy = typename BlockTraits::ChildIteratorType;
690 using PredIterTy = typename InvBlockTraits::ChildIteratorType;
691
692 using BBtoBBMap = DenseMap<BlockT *, BlockT *>;
693 using BBtoRegionMap = DenseMap<BlockT *, RegionT *>;
694
695 RegionInfoBase();
696
697 RegionInfoBase(RegionInfoBase &&Arg)
698 : DT(std::move(Arg.DT)), PDT(std::move(Arg.PDT)), DF(std::move(Arg.DF)),
699 TopLevelRegion(std::move(Arg.TopLevelRegion)),
700 BBtoRegion(std::move(Arg.BBtoRegion)) {
701 Arg.wipe();
702 }
703
704 RegionInfoBase &operator=(RegionInfoBase &&RHS) {
705 DT = std::move(RHS.DT);
706 PDT = std::move(RHS.PDT);
707 DF = std::move(RHS.DF);
708 TopLevelRegion = std::move(RHS.TopLevelRegion);
709 BBtoRegion = std::move(RHS.BBtoRegion);
710 RHS.wipe();
711 return *this;
712 }
713
714 ~RegionInfoBase();
715
716 DomTreeT *DT;
717 PostDomTreeT *PDT;
718 DomFrontierT *DF;
719
720 /// The top level region.
721 RegionT *TopLevelRegion = nullptr;
722
723 /// Map every BB to the smallest region, that contains BB.
724 BBtoRegionMap BBtoRegion;
725
726protected:
727 /// Update refences to a RegionInfoT held by the RegionT managed here
728 ///
729 /// This is a post-move helper. Regions hold references to the owning
730 /// RegionInfo object. After a move these need to be fixed.
731 template<typename TheRegionT>
732 void updateRegionTree(RegionInfoT &RI, TheRegionT *R) {
733 if (!R)
734 return;
735 R->RI = &RI;
736 for (auto &SubR : *R)
737 updateRegionTree(RI, SubR.get());
738 }
739
740private:
741 /// Wipe this region tree's state without releasing any resources.
742 ///
743 /// This is essentially a post-move helper only. It leaves the object in an
744 /// assignable and destroyable state, but otherwise invalid.
745 void wipe() {
746 DT = nullptr;
747 PDT = nullptr;
748 DF = nullptr;
749 TopLevelRegion = nullptr;
750 BBtoRegion.clear();
751 }
752
753 // Check whether the entries of BBtoRegion for the BBs of region
754 // SR are correct. Triggers an assertion if not. Calls itself recursively for
755 // subregions.
756 void verifyBBMap(const RegionT *SR) const;
757
758 // Returns true if BB is in the dominance frontier of
759 // entry, because it was inherited from exit. In the other case there is an
760 // edge going from entry to BB without passing exit.
761 bool isCommonDomFrontier(BlockT *BB, BlockT *entry, BlockT *exit) const;
762
763 // Check if entry and exit surround a valid region, based on
764 // dominance tree and dominance frontier.
765 bool isRegion(BlockT *entry, BlockT *exit) const;
766
767 // Saves a shortcut pointing from entry to exit.
768 // This function may extend this shortcut if possible.
769 void insertShortCut(BlockT *entry, BlockT *exit, BBtoBBMap *ShortCut) const;
770
771 // Returns the next BB that postdominates N, while skipping
772 // all post dominators that cannot finish a canonical region.
773 DomTreeNodeT *getNextPostDom(DomTreeNodeT *N, BBtoBBMap *ShortCut) const;
774
775 // A region is trivial, if it contains only one BB.
776 bool isTrivialRegion(BlockT *entry, BlockT *exit) const;
777
778 // Creates a single entry single exit region.
779 RegionT *createRegion(BlockT *entry, BlockT *exit);
780
781 // Detect all regions starting with bb 'entry'.
782 void findRegionsWithEntry(BlockT *entry, BBtoBBMap *ShortCut);
783
784 // Detects regions in F.
785 void scanForRegions(FuncT &F, BBtoBBMap *ShortCut);
786
787 // Get the top most parent with the same entry block.
788 RegionT *getTopMostParent(RegionT *region);
789
790 // Build the region hierarchy after all region detected.
791 void buildRegionsTree(DomTreeNodeT *N, RegionT *region);
792
793 // Detect all regions in function and build the region tree.
794 void calculate(FuncT &F);
795
796public:
797 RegionInfoBase(const RegionInfoBase &) = delete;
798 RegionInfoBase &operator=(const RegionInfoBase &) = delete;
799
800 static bool VerifyRegionInfo;
801 static typename RegionT::PrintStyle printStyle;
802
803 void print(raw_ostream &OS) const;
804#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
805 void dump() const;
806#endif
807
808 void releaseMemory();
809
810 /// Get the smallest region that contains a BasicBlock.
811 ///
812 /// @param BB The basic block.
813 /// @return The smallest region, that contains BB or NULL, if there is no
814 /// region containing BB.
815 RegionT *getRegionFor(BlockT *BB) const;
816
817 /// Set the smallest region that surrounds a basic block.
818 ///
819 /// @param BB The basic block surrounded by a region.
820 /// @param R The smallest region that surrounds BB.
821 void setRegionFor(BlockT *BB, RegionT *R);
822
823 /// A shortcut for getRegionFor().
824 ///
825 /// @param BB The basic block.
826 /// @return The smallest region, that contains BB or NULL, if there is no
827 /// region containing BB.
828 RegionT *operator[](BlockT *BB) const;
829
830 /// Return the exit of the maximal refined region, that starts at a
831 /// BasicBlock.
832 ///
833 /// @param BB The BasicBlock the refined region starts.
834 BlockT *getMaxRegionExit(BlockT *BB) const;
835
836 /// Find the smallest region that contains two regions.
837 ///
838 /// @param A The first region.
839 /// @param B The second region.
840 /// @return The smallest region containing A and B.
841 RegionT *getCommonRegion(RegionT *A, RegionT *B) const;
842
843 /// Find the smallest region that contains two basic blocks.
844 ///
845 /// @param A The first basic block.
846 /// @param B The second basic block.
847 /// @return The smallest region that contains A and B.
848 RegionT *getCommonRegion(BlockT *A, BlockT *B) const {
849 return getCommonRegion(getRegionFor(BB: A), getRegionFor(BB: B));
850 }
851
852 /// Find the smallest region that contains a set of regions.
853 ///
854 /// @param Regions A vector of regions.
855 /// @return The smallest region that contains all regions in Regions.
856 RegionT *getCommonRegion(SmallVectorImpl<RegionT *> &Regions) const;
857
858 /// Find the smallest region that contains a set of basic blocks.
859 ///
860 /// @param BBs A vector of basic blocks.
861 /// @return The smallest region that contains all basic blocks in BBS.
862 RegionT *getCommonRegion(SmallVectorImpl<BlockT *> &BBs) const;
863
864 RegionT *getTopLevelRegion() const { return TopLevelRegion; }
865
866 /// Clear the Node Cache for all Regions.
867 ///
868 /// @see Region::clearNodeCache()
869 void clearNodeCache() {
870 if (TopLevelRegion)
871 TopLevelRegion->clearNodeCache();
872 }
873
874 void verifyAnalysis() const;
875};
876
877extern template class LLVM_TEMPLATE_ABI RegionNodeBase<RegionTraits<Function>>;
878
879class RegionNode : public RegionNodeBase<RegionTraits<Function>> {
880public:
881 inline RegionNode(Region *Parent, BasicBlock *Entry, bool isSubRegion = false)
882 : RegionNodeBase<RegionTraits<Function>>(Parent, Entry, isSubRegion) {}
883
884 bool operator==(const Region &RN) const {
885 return this == reinterpret_cast<const RegionNode *>(&RN);
886 }
887};
888
889extern template class LLVM_TEMPLATE_ABI RegionBase<RegionTraits<Function>>;
890
891class Region : public RegionBase<RegionTraits<Function>> {
892public:
893 LLVM_ABI Region(BasicBlock *Entry, BasicBlock *Exit, RegionInfo *RI,
894 DominatorTree *DT, Region *Parent = nullptr);
895 LLVM_ABI ~Region();
896
897 bool operator==(const RegionNode &RN) const {
898 return &RN == reinterpret_cast<const RegionNode *>(this);
899 }
900};
901
902extern template class LLVM_TEMPLATE_ABI RegionInfoBase<RegionTraits<Function>>;
903
904class RegionInfo : public RegionInfoBase<RegionTraits<Function>> {
905public:
906 using Base = RegionInfoBase<RegionTraits<Function>>;
907
908 LLVM_ABI explicit RegionInfo();
909
910 RegionInfo(RegionInfo &&Arg) : Base(std::move(static_cast<Base &>(Arg))) {
911 updateRegionTree(RI&: *this, R: TopLevelRegion);
912 }
913
914 RegionInfo &operator=(RegionInfo &&RHS) {
915 Base::operator=(RHS: std::move(static_cast<Base &>(RHS)));
916 updateRegionTree(RI&: *this, R: TopLevelRegion);
917 return *this;
918 }
919
920 LLVM_ABI ~RegionInfo();
921
922 /// Handle invalidation explicitly.
923 LLVM_ABI bool invalidate(Function &F, const PreservedAnalyses &PA,
924 FunctionAnalysisManager::Invalidator &);
925
926 LLVM_ABI void recalculate(Function &F, DominatorTree *DT,
927 PostDominatorTree *PDT, DominanceFrontier *DF);
928
929#ifndef NDEBUG
930 /// Opens a viewer to show the GraphViz visualization of the regions.
931 ///
932 /// Useful during debugging as an alternative to dump().
933 LLVM_ABI void view();
934
935 /// Opens a viewer to show the GraphViz visualization of this region
936 /// without instructions in the BasicBlocks.
937 ///
938 /// Useful during debugging as an alternative to dump().
939 LLVM_ABI void viewOnly();
940#endif
941};
942
943class LLVM_ABI RegionInfoPass : public FunctionPass {
944 RegionInfo RI;
945
946public:
947 static char ID;
948
949 explicit RegionInfoPass();
950 ~RegionInfoPass() override;
951
952 RegionInfo &getRegionInfo() { return RI; }
953
954 const RegionInfo &getRegionInfo() const { return RI; }
955
956 /// @name FunctionPass interface
957 //@{
958 bool runOnFunction(Function &F) override;
959 void releaseMemory() override;
960 void verifyAnalysis() const override;
961 void getAnalysisUsage(AnalysisUsage &AU) const override;
962 void print(raw_ostream &OS, const Module *) const override;
963 void dump() const;
964 //@}
965};
966
967/// Analysis pass that exposes the \c RegionInfo for a function.
968class RegionInfoAnalysis : public AnalysisInfoMixin<RegionInfoAnalysis> {
969 friend AnalysisInfoMixin<RegionInfoAnalysis>;
970
971 static AnalysisKey Key;
972
973public:
974 using Result = RegionInfo;
975
976 LLVM_ABI RegionInfo run(Function &F, FunctionAnalysisManager &AM);
977};
978
979/// Printer pass for the \c RegionInfo.
980class RegionInfoPrinterPass
981 : public RequiredPassInfoMixin<RegionInfoPrinterPass> {
982 raw_ostream &OS;
983
984public:
985 LLVM_ABI explicit RegionInfoPrinterPass(raw_ostream &OS);
986
987 LLVM_ABI PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
988};
989
990/// Verifier pass for the \c RegionInfo.
991struct RegionInfoVerifierPass : RequiredPassInfoMixin<RegionInfoVerifierPass> {
992 LLVM_ABI PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
993};
994
995template <>
996template <>
997inline BasicBlock *
998RegionNodeBase<RegionTraits<Function>>::getNodeAs<BasicBlock>() const {
999 assert(!isSubRegion() && "This is not a BasicBlock RegionNode!");
1000 return getEntry();
1001}
1002
1003template <>
1004template <>
1005inline Region *
1006RegionNodeBase<RegionTraits<Function>>::getNodeAs<Region>() const {
1007 assert(isSubRegion() && "This is not a subregion RegionNode!");
1008 auto Unconst = const_cast<RegionNodeBase<RegionTraits<Function>> *>(this);
1009 return reinterpret_cast<Region *>(Unconst);
1010}
1011
1012template <class Tr>
1013inline raw_ostream &operator<<(raw_ostream &OS,
1014 const RegionNodeBase<Tr> &Node) {
1015 using BlockT = typename Tr::BlockT;
1016 using RegionT = typename Tr::RegionT;
1017
1018 if (Node.isSubRegion())
1019 return OS << Node.template getNodeAs<RegionT>()->getNameStr();
1020 else
1021 return OS << Node.template getNodeAs<BlockT>()->getName();
1022}
1023
1024} // end namespace llvm
1025
1026#endif // LLVM_ANALYSIS_REGIONINFO_H
1027