LLVM  3.7.0
BlockFrequencyInfoImpl.h
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1 //==- BlockFrequencyInfoImpl.h - Block Frequency Implementation -*- C++ -*-===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // Shared implementation of BlockFrequency for IR and Machine Instructions.
11 // See the documentation below for BlockFrequencyInfoImpl for details.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #ifndef LLVM_ANALYSIS_BLOCKFREQUENCYINFOIMPL_H
16 #define LLVM_ANALYSIS_BLOCKFREQUENCYINFOIMPL_H
17 
18 #include "llvm/ADT/DenseMap.h"
21 #include "llvm/IR/BasicBlock.h"
24 #include "llvm/Support/Debug.h"
27 #include <deque>
28 #include <list>
29 #include <string>
30 #include <vector>
31 
32 #define DEBUG_TYPE "block-freq"
33 
34 namespace llvm {
35 
36 class BasicBlock;
37 class BranchProbabilityInfo;
38 class Function;
39 class Loop;
40 class LoopInfo;
41 class MachineBasicBlock;
42 class MachineBranchProbabilityInfo;
43 class MachineFunction;
44 class MachineLoop;
45 class MachineLoopInfo;
46 
47 namespace bfi_detail {
48 
49 struct IrreducibleGraph;
50 
51 // This is part of a workaround for a GCC 4.7 crash on lambdas.
52 template <class BT> struct BlockEdgesAdder;
53 
54 /// \brief Mass of a block.
55 ///
56 /// This class implements a sort of fixed-point fraction always between 0.0 and
57 /// 1.0. getMass() == UINT64_MAX indicates a value of 1.0.
58 ///
59 /// Masses can be added and subtracted. Simple saturation arithmetic is used,
60 /// so arithmetic operations never overflow or underflow.
61 ///
62 /// Masses can be multiplied. Multiplication treats full mass as 1.0 and uses
63 /// an inexpensive floating-point algorithm that's off-by-one (almost, but not
64 /// quite, maximum precision).
65 ///
66 /// Masses can be scaled by \a BranchProbability at maximum precision.
67 class BlockMass {
68  uint64_t Mass;
69 
70 public:
71  BlockMass() : Mass(0) {}
72  explicit BlockMass(uint64_t Mass) : Mass(Mass) {}
73 
74  static BlockMass getEmpty() { return BlockMass(); }
75  static BlockMass getFull() { return BlockMass(UINT64_MAX); }
76 
77  uint64_t getMass() const { return Mass; }
78 
79  bool isFull() const { return Mass == UINT64_MAX; }
80  bool isEmpty() const { return !Mass; }
81 
82  bool operator!() const { return isEmpty(); }
83 
84  /// \brief Add another mass.
85  ///
86  /// Adds another mass, saturating at \a isFull() rather than overflowing.
88  uint64_t Sum = Mass + X.Mass;
89  Mass = Sum < Mass ? UINT64_MAX : Sum;
90  return *this;
91  }
92 
93  /// \brief Subtract another mass.
94  ///
95  /// Subtracts another mass, saturating at \a isEmpty() rather than
96  /// undeflowing.
98  uint64_t Diff = Mass - X.Mass;
99  Mass = Diff > Mass ? 0 : Diff;
100  return *this;
101  }
102 
104  Mass = P.scale(Mass);
105  return *this;
106  }
107 
108  bool operator==(const BlockMass &X) const { return Mass == X.Mass; }
109  bool operator!=(const BlockMass &X) const { return Mass != X.Mass; }
110  bool operator<=(const BlockMass &X) const { return Mass <= X.Mass; }
111  bool operator>=(const BlockMass &X) const { return Mass >= X.Mass; }
112  bool operator<(const BlockMass &X) const { return Mass < X.Mass; }
113  bool operator>(const BlockMass &X) const { return Mass > X.Mass; }
114 
115  /// \brief Convert to scaled number.
116  ///
117  /// Convert to \a ScaledNumber. \a isFull() gives 1.0, while \a isEmpty()
118  /// gives slightly above 0.0.
120 
121  void dump() const;
122  raw_ostream &print(raw_ostream &OS) const;
123 };
124 
125 inline BlockMass operator+(const BlockMass &L, const BlockMass &R) {
126  return BlockMass(L) += R;
127 }
128 inline BlockMass operator-(const BlockMass &L, const BlockMass &R) {
129  return BlockMass(L) -= R;
130 }
131 inline BlockMass operator*(const BlockMass &L, const BranchProbability &R) {
132  return BlockMass(L) *= R;
133 }
134 inline BlockMass operator*(const BranchProbability &L, const BlockMass &R) {
135  return BlockMass(R) *= L;
136 }
137 
139  return X.print(OS);
140 }
141 
142 } // end namespace bfi_detail
143 
144 template <> struct isPodLike<bfi_detail::BlockMass> {
145  static const bool value = true;
146 };
147 
148 /// \brief Base class for BlockFrequencyInfoImpl
149 ///
150 /// BlockFrequencyInfoImplBase has supporting data structures and some
151 /// algorithms for BlockFrequencyInfoImplBase. Only algorithms that depend on
152 /// the block type (or that call such algorithms) are skipped here.
153 ///
154 /// Nevertheless, the majority of the overall algorithm documention lives with
155 /// BlockFrequencyInfoImpl. See there for details.
157 public:
160 
161  /// \brief Representative of a block.
162  ///
163  /// This is a simple wrapper around an index into the reverse-post-order
164  /// traversal of the blocks.
165  ///
166  /// Unlike a block pointer, its order has meaning (location in the
167  /// topological sort) and it's class is the same regardless of block type.
168  struct BlockNode {
169  typedef uint32_t IndexType;
171 
172  bool operator==(const BlockNode &X) const { return Index == X.Index; }
173  bool operator!=(const BlockNode &X) const { return Index != X.Index; }
174  bool operator<=(const BlockNode &X) const { return Index <= X.Index; }
175  bool operator>=(const BlockNode &X) const { return Index >= X.Index; }
176  bool operator<(const BlockNode &X) const { return Index < X.Index; }
177  bool operator>(const BlockNode &X) const { return Index > X.Index; }
178 
179  BlockNode() : Index(UINT32_MAX) {}
180  BlockNode(IndexType Index) : Index(Index) {}
181 
182  bool isValid() const { return Index <= getMaxIndex(); }
183  static size_t getMaxIndex() { return UINT32_MAX - 1; }
184  };
185 
186  /// \brief Stats about a block itself.
187  struct FrequencyData {
189  uint64_t Integer;
190  };
191 
192  /// \brief Data about a loop.
193  ///
194  /// Contains the data necessary to represent a loop as a pseudo-node once it's
195  /// packaged.
196  struct LoopData {
200  LoopData *Parent; ///< The parent loop.
201  bool IsPackaged; ///< Whether this has been packaged.
202  uint32_t NumHeaders; ///< Number of headers.
203  ExitMap Exits; ///< Successor edges (and weights).
204  NodeList Nodes; ///< Header and the members of the loop.
205  HeaderMassList BackedgeMass; ///< Mass returned to each loop header.
208 
210  : Parent(Parent), IsPackaged(false), NumHeaders(1), Nodes(1, Header),
211  BackedgeMass(1) {}
212  template <class It1, class It2>
213  LoopData(LoopData *Parent, It1 FirstHeader, It1 LastHeader, It2 FirstOther,
214  It2 LastOther)
215  : Parent(Parent), IsPackaged(false), Nodes(FirstHeader, LastHeader) {
216  NumHeaders = Nodes.size();
217  Nodes.insert(Nodes.end(), FirstOther, LastOther);
219  }
220  bool isHeader(const BlockNode &Node) const {
221  if (isIrreducible())
222  return std::binary_search(Nodes.begin(), Nodes.begin() + NumHeaders,
223  Node);
224  return Node == Nodes[0];
225  }
226  BlockNode getHeader() const { return Nodes[0]; }
227  bool isIrreducible() const { return NumHeaders > 1; }
228 
230  assert(isHeader(B) && "this is only valid on loop header blocks");
231  if (isIrreducible())
232  return std::lower_bound(Nodes.begin(), Nodes.begin() + NumHeaders, B) -
233  Nodes.begin();
234  return 0;
235  }
236 
238  return Nodes.begin() + NumHeaders;
239  }
242  return make_range(members_begin(), members_end());
243  }
244  };
245 
246  /// \brief Index of loop information.
247  struct WorkingData {
248  BlockNode Node; ///< This node.
249  LoopData *Loop; ///< The loop this block is inside.
250  BlockMass Mass; ///< Mass distribution from the entry block.
251 
252  WorkingData(const BlockNode &Node) : Node(Node), Loop(nullptr) {}
253 
254  bool isLoopHeader() const { return Loop && Loop->isHeader(Node); }
255  bool isDoubleLoopHeader() const {
256  return isLoopHeader() && Loop->Parent && Loop->Parent->isIrreducible() &&
257  Loop->Parent->isHeader(Node);
258  }
259 
261  if (!isLoopHeader())
262  return Loop;
263  if (!isDoubleLoopHeader())
264  return Loop->Parent;
265  return Loop->Parent->Parent;
266  }
267 
268  /// \brief Resolve a node to its representative.
269  ///
270  /// Get the node currently representing Node, which could be a containing
271  /// loop.
272  ///
273  /// This function should only be called when distributing mass. As long as
274  /// there are no irreducible edges to Node, then it will have complexity
275  /// O(1) in this context.
276  ///
277  /// In general, the complexity is O(L), where L is the number of loop
278  /// headers Node has been packaged into. Since this method is called in
279  /// the context of distributing mass, L will be the number of loop headers
280  /// an early exit edge jumps out of.
282  auto L = getPackagedLoop();
283  return L ? L->getHeader() : Node;
284  }
286  if (!Loop || !Loop->IsPackaged)
287  return nullptr;
288  auto L = Loop;
289  while (L->Parent && L->Parent->IsPackaged)
290  L = L->Parent;
291  return L;
292  }
293 
294  /// \brief Get the appropriate mass for a node.
295  ///
296  /// Get appropriate mass for Node. If Node is a loop-header (whose loop
297  /// has been packaged), returns the mass of its pseudo-node. If it's a
298  /// node inside a packaged loop, it returns the loop's mass.
300  if (!isAPackage())
301  return Mass;
302  if (!isADoublePackage())
303  return Loop->Mass;
304  return Loop->Parent->Mass;
305  }
306 
307  /// \brief Has ContainingLoop been packaged up?
308  bool isPackaged() const { return getResolvedNode() != Node; }
309  /// \brief Has Loop been packaged up?
310  bool isAPackage() const { return isLoopHeader() && Loop->IsPackaged; }
311  /// \brief Has Loop been packaged up twice?
312  bool isADoublePackage() const {
313  return isDoubleLoopHeader() && Loop->Parent->IsPackaged;
314  }
315  };
316 
317  /// \brief Unscaled probability weight.
318  ///
319  /// Probability weight for an edge in the graph (including the
320  /// successor/target node).
321  ///
322  /// All edges in the original function are 32-bit. However, exit edges from
323  /// loop packages are taken from 64-bit exit masses, so we need 64-bits of
324  /// space in general.
325  ///
326  /// In addition to the raw weight amount, Weight stores the type of the edge
327  /// in the current context (i.e., the context of the loop being processed).
328  /// Is this a local edge within the loop, an exit from the loop, or a
329  /// backedge to the loop header?
330  struct Weight {
334  uint64_t Amount;
335  Weight() : Type(Local), Amount(0) {}
337  : Type(Type), TargetNode(TargetNode), Amount(Amount) {}
338  };
339 
340  /// \brief Distribution of unscaled probability weight.
341  ///
342  /// Distribution of unscaled probability weight to a set of successors.
343  ///
344  /// This class collates the successor edge weights for later processing.
345  ///
346  /// \a DidOverflow indicates whether \a Total did overflow while adding to
347  /// the distribution. It should never overflow twice.
348  struct Distribution {
350  WeightList Weights; ///< Individual successor weights.
351  uint64_t Total; ///< Sum of all weights.
352  bool DidOverflow; ///< Whether \a Total did overflow.
353 
355  void addLocal(const BlockNode &Node, uint64_t Amount) {
356  add(Node, Amount, Weight::Local);
357  }
358  void addExit(const BlockNode &Node, uint64_t Amount) {
359  add(Node, Amount, Weight::Exit);
360  }
361  void addBackedge(const BlockNode &Node, uint64_t Amount) {
362  add(Node, Amount, Weight::Backedge);
363  }
364 
365  /// \brief Normalize the distribution.
366  ///
367  /// Combines multiple edges to the same \a Weight::TargetNode and scales
368  /// down so that \a Total fits into 32-bits.
369  ///
370  /// This is linear in the size of \a Weights. For the vast majority of
371  /// cases, adjacent edge weights are combined by sorting WeightList and
372  /// combining adjacent weights. However, for very large edge lists an
373  /// auxiliary hash table is used.
374  void normalize();
375 
376  private:
377  void add(const BlockNode &Node, uint64_t Amount, Weight::DistType Type);
378  };
379 
380  /// \brief Data about each block. This is used downstream.
381  std::vector<FrequencyData> Freqs;
382 
383  /// \brief Loop data: see initializeLoops().
384  std::vector<WorkingData> Working;
385 
386  /// \brief Indexed information about loops.
387  std::list<LoopData> Loops;
388 
389  /// \brief Add all edges out of a packaged loop to the distribution.
390  ///
391  /// Adds all edges from LocalLoopHead to Dist. Calls addToDist() to add each
392  /// successor edge.
393  ///
394  /// \return \c true unless there's an irreducible backedge.
395  bool addLoopSuccessorsToDist(const LoopData *OuterLoop, LoopData &Loop,
396  Distribution &Dist);
397 
398  /// \brief Add an edge to the distribution.
399  ///
400  /// Adds an edge to Succ to Dist. If \c LoopHead.isValid(), then whether the
401  /// edge is local/exit/backedge is in the context of LoopHead. Otherwise,
402  /// every edge should be a local edge (since all the loops are packaged up).
403  ///
404  /// \return \c true unless aborted due to an irreducible backedge.
405  bool addToDist(Distribution &Dist, const LoopData *OuterLoop,
406  const BlockNode &Pred, const BlockNode &Succ, uint64_t Weight);
407 
409  assert(Head.Index < Working.size());
410  assert(Working[Head.Index].isLoopHeader());
411  return *Working[Head.Index].Loop;
412  }
413 
414  /// \brief Analyze irreducible SCCs.
415  ///
416  /// Separate irreducible SCCs from \c G, which is an explict graph of \c
417  /// OuterLoop (or the top-level function, if \c OuterLoop is \c nullptr).
418  /// Insert them into \a Loops before \c Insert.
419  ///
420  /// \return the \c LoopData nodes representing the irreducible SCCs.
422  analyzeIrreducible(const bfi_detail::IrreducibleGraph &G, LoopData *OuterLoop,
423  std::list<LoopData>::iterator Insert);
424 
425  /// \brief Update a loop after packaging irreducible SCCs inside of it.
426  ///
427  /// Update \c OuterLoop. Before finding irreducible control flow, it was
428  /// partway through \a computeMassInLoop(), so \a LoopData::Exits and \a
429  /// LoopData::BackedgeMass need to be reset. Also, nodes that were packaged
430  /// up need to be removed from \a OuterLoop::Nodes.
431  void updateLoopWithIrreducible(LoopData &OuterLoop);
432 
433  /// \brief Distribute mass according to a distribution.
434  ///
435  /// Distributes the mass in Source according to Dist. If LoopHead.isValid(),
436  /// backedges and exits are stored in its entry in Loops.
437  ///
438  /// Mass is distributed in parallel from two copies of the source mass.
439  void distributeMass(const BlockNode &Source, LoopData *OuterLoop,
440  Distribution &Dist);
441 
442  /// \brief Compute the loop scale for a loop.
443  void computeLoopScale(LoopData &Loop);
444 
445  /// Adjust the mass of all headers in an irreducible loop.
446  ///
447  /// Initially, irreducible loops are assumed to distribute their mass
448  /// equally among its headers. This can lead to wrong frequency estimates
449  /// since some headers may be executed more frequently than others.
450  ///
451  /// This adjusts header mass distribution so it matches the weights of
452  /// the backedges going into each of the loop headers.
453  void adjustLoopHeaderMass(LoopData &Loop);
454 
455  /// \brief Package up a loop.
456  void packageLoop(LoopData &Loop);
457 
458  /// \brief Unwrap loops.
459  void unwrapLoops();
460 
461  /// \brief Finalize frequency metrics.
462  ///
463  /// Calculates final frequencies and cleans up no-longer-needed data
464  /// structures.
465  void finalizeMetrics();
466 
467  /// \brief Clear all memory.
468  void clear();
469 
470  virtual std::string getBlockName(const BlockNode &Node) const;
471  std::string getLoopName(const LoopData &Loop) const;
472 
473  virtual raw_ostream &print(raw_ostream &OS) const { return OS; }
474  void dump() const { print(dbgs()); }
475 
476  Scaled64 getFloatingBlockFreq(const BlockNode &Node) const;
477 
478  BlockFrequency getBlockFreq(const BlockNode &Node) const;
479 
480  raw_ostream &printBlockFreq(raw_ostream &OS, const BlockNode &Node) const;
482  const BlockFrequency &Freq) const;
483 
484  uint64_t getEntryFreq() const {
485  assert(!Freqs.empty());
486  return Freqs[0].Integer;
487  }
488  /// \brief Virtual destructor.
489  ///
490  /// Need a virtual destructor to mask the compiler warning about
491  /// getBlockName().
493 };
494 
495 namespace bfi_detail {
496 template <class BlockT> struct TypeMap {};
497 template <> struct TypeMap<BasicBlock> {
501  typedef Loop LoopT;
503 };
504 template <> struct TypeMap<MachineBasicBlock> {
510 };
511 
512 /// \brief Get the name of a MachineBasicBlock.
513 ///
514 /// Get the name of a MachineBasicBlock. It's templated so that including from
515 /// CodeGen is unnecessary (that would be a layering issue).
516 ///
517 /// This is used mainly for debug output. The name is similar to
518 /// MachineBasicBlock::getFullName(), but skips the name of the function.
519 template <class BlockT> std::string getBlockName(const BlockT *BB) {
520  assert(BB && "Unexpected nullptr");
521  auto MachineName = "BB" + Twine(BB->getNumber());
522  if (BB->getBasicBlock())
523  return (MachineName + "[" + BB->getName() + "]").str();
524  return MachineName.str();
525 }
526 /// \brief Get the name of a BasicBlock.
527 template <> inline std::string getBlockName(const BasicBlock *BB) {
528  assert(BB && "Unexpected nullptr");
529  return BB->getName().str();
530 }
531 
532 /// \brief Graph of irreducible control flow.
533 ///
534 /// This graph is used for determining the SCCs in a loop (or top-level
535 /// function) that has irreducible control flow.
536 ///
537 /// During the block frequency algorithm, the local graphs are defined in a
538 /// light-weight way, deferring to the \a BasicBlock or \a MachineBasicBlock
539 /// graphs for most edges, but getting others from \a LoopData::ExitMap. The
540 /// latter only has successor information.
541 ///
542 /// \a IrreducibleGraph makes this graph explicit. It's in a form that can use
543 /// \a GraphTraits (so that \a analyzeIrreducible() can use \a scc_iterator),
544 /// and it explicitly lists predecessors and successors. The initialization
545 /// that relies on \c MachineBasicBlock is defined in the header.
548 
550 
552  struct IrrNode {
554  unsigned NumIn;
555  std::deque<const IrrNode *> Edges;
556  IrrNode(const BlockNode &Node) : Node(Node), NumIn(0) {}
557 
558  typedef std::deque<const IrrNode *>::const_iterator iterator;
559  iterator pred_begin() const { return Edges.begin(); }
560  iterator succ_begin() const { return Edges.begin() + NumIn; }
561  iterator pred_end() const { return succ_begin(); }
562  iterator succ_end() const { return Edges.end(); }
563  };
566  std::vector<IrrNode> Nodes;
568 
569  /// \brief Construct an explicit graph containing irreducible control flow.
570  ///
571  /// Construct an explicit graph of the control flow in \c OuterLoop (or the
572  /// top-level function, if \c OuterLoop is \c nullptr). Uses \c
573  /// addBlockEdges to add block successors that have not been packaged into
574  /// loops.
575  ///
576  /// \a BlockFrequencyInfoImpl::computeIrreducibleMass() is the only expected
577  /// user of this.
578  template <class BlockEdgesAdder>
580  BlockEdgesAdder addBlockEdges)
581  : BFI(BFI), StartIrr(nullptr) {
582  initialize(OuterLoop, addBlockEdges);
583  }
584 
585  template <class BlockEdgesAdder>
586  void initialize(const BFIBase::LoopData *OuterLoop,
587  BlockEdgesAdder addBlockEdges);
588  void addNodesInLoop(const BFIBase::LoopData &OuterLoop);
589  void addNodesInFunction();
590  void addNode(const BlockNode &Node) {
591  Nodes.emplace_back(Node);
592  BFI.Working[Node.Index].getMass() = BlockMass::getEmpty();
593  }
594  void indexNodes();
595  template <class BlockEdgesAdder>
596  void addEdges(const BlockNode &Node, const BFIBase::LoopData *OuterLoop,
597  BlockEdgesAdder addBlockEdges);
598  void addEdge(IrrNode &Irr, const BlockNode &Succ,
599  const BFIBase::LoopData *OuterLoop);
600 };
601 template <class BlockEdgesAdder>
603  BlockEdgesAdder addBlockEdges) {
604  if (OuterLoop) {
605  addNodesInLoop(*OuterLoop);
606  for (auto N : OuterLoop->Nodes)
607  addEdges(N, OuterLoop, addBlockEdges);
608  } else {
610  for (uint32_t Index = 0; Index < BFI.Working.size(); ++Index)
611  addEdges(Index, OuterLoop, addBlockEdges);
612  }
614 }
615 template <class BlockEdgesAdder>
617  const BFIBase::LoopData *OuterLoop,
618  BlockEdgesAdder addBlockEdges) {
619  auto L = Lookup.find(Node.Index);
620  if (L == Lookup.end())
621  return;
622  IrrNode &Irr = *L->second;
623  const auto &Working = BFI.Working[Node.Index];
624 
625  if (Working.isAPackage())
626  for (const auto &I : Working.Loop->Exits)
627  addEdge(Irr, I.first, OuterLoop);
628  else
629  addBlockEdges(*this, Irr, OuterLoop);
630 }
631 }
632 
633 /// \brief Shared implementation for block frequency analysis.
634 ///
635 /// This is a shared implementation of BlockFrequencyInfo and
636 /// MachineBlockFrequencyInfo, and calculates the relative frequencies of
637 /// blocks.
638 ///
639 /// LoopInfo defines a loop as a "non-trivial" SCC dominated by a single block,
640 /// which is called the header. A given loop, L, can have sub-loops, which are
641 /// loops within the subgraph of L that exclude its header. (A "trivial" SCC
642 /// consists of a single block that does not have a self-edge.)
643 ///
644 /// In addition to loops, this algorithm has limited support for irreducible
645 /// SCCs, which are SCCs with multiple entry blocks. Irreducible SCCs are
646 /// discovered on they fly, and modelled as loops with multiple headers.
647 ///
648 /// The headers of irreducible sub-SCCs consist of its entry blocks and all
649 /// nodes that are targets of a backedge within it (excluding backedges within
650 /// true sub-loops). Block frequency calculations act as if a block is
651 /// inserted that intercepts all the edges to the headers. All backedges and
652 /// entries point to this block. Its successors are the headers, which split
653 /// the frequency evenly.
654 ///
655 /// This algorithm leverages BlockMass and ScaledNumber to maintain precision,
656 /// separates mass distribution from loop scaling, and dithers to eliminate
657 /// probability mass loss.
658 ///
659 /// The implementation is split between BlockFrequencyInfoImpl, which knows the
660 /// type of graph being modelled (BasicBlock vs. MachineBasicBlock), and
661 /// BlockFrequencyInfoImplBase, which doesn't. The base class uses \a
662 /// BlockNode, a wrapper around a uint32_t. BlockNode is numbered from 0 in
663 /// reverse-post order. This gives two advantages: it's easy to compare the
664 /// relative ordering of two nodes, and maps keyed on BlockT can be represented
665 /// by vectors.
666 ///
667 /// This algorithm is O(V+E), unless there is irreducible control flow, in
668 /// which case it's O(V*E) in the worst case.
669 ///
670 /// These are the main stages:
671 ///
672 /// 0. Reverse post-order traversal (\a initializeRPOT()).
673 ///
674 /// Run a single post-order traversal and save it (in reverse) in RPOT.
675 /// All other stages make use of this ordering. Save a lookup from BlockT
676 /// to BlockNode (the index into RPOT) in Nodes.
677 ///
678 /// 1. Loop initialization (\a initializeLoops()).
679 ///
680 /// Translate LoopInfo/MachineLoopInfo into a form suitable for the rest of
681 /// the algorithm. In particular, store the immediate members of each loop
682 /// in reverse post-order.
683 ///
684 /// 2. Calculate mass and scale in loops (\a computeMassInLoops()).
685 ///
686 /// For each loop (bottom-up), distribute mass through the DAG resulting
687 /// from ignoring backedges and treating sub-loops as a single pseudo-node.
688 /// Track the backedge mass distributed to the loop header, and use it to
689 /// calculate the loop scale (number of loop iterations). Immediate
690 /// members that represent sub-loops will already have been visited and
691 /// packaged into a pseudo-node.
692 ///
693 /// Distributing mass in a loop is a reverse-post-order traversal through
694 /// the loop. Start by assigning full mass to the Loop header. For each
695 /// node in the loop:
696 ///
697 /// - Fetch and categorize the weight distribution for its successors.
698 /// If this is a packaged-subloop, the weight distribution is stored
699 /// in \a LoopData::Exits. Otherwise, fetch it from
700 /// BranchProbabilityInfo.
701 ///
702 /// - Each successor is categorized as \a Weight::Local, a local edge
703 /// within the current loop, \a Weight::Backedge, a backedge to the
704 /// loop header, or \a Weight::Exit, any successor outside the loop.
705 /// The weight, the successor, and its category are stored in \a
706 /// Distribution. There can be multiple edges to each successor.
707 ///
708 /// - If there's a backedge to a non-header, there's an irreducible SCC.
709 /// The usual flow is temporarily aborted. \a
710 /// computeIrreducibleMass() finds the irreducible SCCs within the
711 /// loop, packages them up, and restarts the flow.
712 ///
713 /// - Normalize the distribution: scale weights down so that their sum
714 /// is 32-bits, and coalesce multiple edges to the same node.
715 ///
716 /// - Distribute the mass accordingly, dithering to minimize mass loss,
717 /// as described in \a distributeMass().
718 ///
719 /// In the case of irreducible loops, instead of a single loop header,
720 /// there will be several. The computation of backedge masses is similar
721 /// but instead of having a single backedge mass, there will be one
722 /// backedge per loop header. In these cases, each backedge will carry
723 /// a mass proportional to the edge weights along the corresponding
724 /// path.
725 ///
726 /// At the end of propagation, the full mass assigned to the loop will be
727 /// distributed among the loop headers proportionally according to the
728 /// mass flowing through their backedges.
729 ///
730 /// Finally, calculate the loop scale from the accumulated backedge mass.
731 ///
732 /// 3. Distribute mass in the function (\a computeMassInFunction()).
733 ///
734 /// Finally, distribute mass through the DAG resulting from packaging all
735 /// loops in the function. This uses the same algorithm as distributing
736 /// mass in a loop, except that there are no exit or backedge edges.
737 ///
738 /// 4. Unpackage loops (\a unwrapLoops()).
739 ///
740 /// Initialize each block's frequency to a floating point representation of
741 /// its mass.
742 ///
743 /// Visit loops top-down, scaling the frequencies of its immediate members
744 /// by the loop's pseudo-node's frequency.
745 ///
746 /// 5. Convert frequencies to a 64-bit range (\a finalizeMetrics()).
747 ///
748 /// Using the min and max frequencies as a guide, translate floating point
749 /// frequencies to an appropriate range in uint64_t.
750 ///
751 /// It has some known flaws.
752 ///
753 /// - The model of irreducible control flow is a rough approximation.
754 ///
755 /// Modelling irreducible control flow exactly involves setting up and
756 /// solving a group of infinite geometric series. Such precision is
757 /// unlikely to be worthwhile, since most of our algorithms give up on
758 /// irreducible control flow anyway.
759 ///
760 /// Nevertheless, we might find that we need to get closer. Here's a sort
761 /// of TODO list for the model with diminishing returns, to be completed as
762 /// necessary.
763 ///
764 /// - The headers for the \a LoopData representing an irreducible SCC
765 /// include non-entry blocks. When these extra blocks exist, they
766 /// indicate a self-contained irreducible sub-SCC. We could treat them
767 /// as sub-loops, rather than arbitrarily shoving the problematic
768 /// blocks into the headers of the main irreducible SCC.
769 ///
770 /// - Entry frequencies are assumed to be evenly split between the
771 /// headers of a given irreducible SCC, which is the only option if we
772 /// need to compute mass in the SCC before its parent loop. Instead,
773 /// we could partially compute mass in the parent loop, and stop when
774 /// we get to the SCC. Here, we have the correct ratio of entry
775 /// masses, which we can use to adjust their relative frequencies.
776 /// Compute mass in the SCC, and then continue propagation in the
777 /// parent.
778 ///
779 /// - We can propagate mass iteratively through the SCC, for some fixed
780 /// number of iterations. Each iteration starts by assigning the entry
781 /// blocks their backedge mass from the prior iteration. The final
782 /// mass for each block (and each exit, and the total backedge mass
783 /// used for computing loop scale) is the sum of all iterations.
784 /// (Running this until fixed point would "solve" the geometric
785 /// series by simulation.)
786 template <class BT> class BlockFrequencyInfoImpl : BlockFrequencyInfoImplBase {
787  typedef typename bfi_detail::TypeMap<BT>::BlockT BlockT;
788  typedef typename bfi_detail::TypeMap<BT>::FunctionT FunctionT;
790  BranchProbabilityInfoT;
791  typedef typename bfi_detail::TypeMap<BT>::LoopT LoopT;
792  typedef typename bfi_detail::TypeMap<BT>::LoopInfoT LoopInfoT;
793 
794  // This is part of a workaround for a GCC 4.7 crash on lambdas.
796 
799 
800  const BranchProbabilityInfoT *BPI;
801  const LoopInfoT *LI;
802  const FunctionT *F;
803 
804  // All blocks in reverse postorder.
805  std::vector<const BlockT *> RPOT;
807 
808  typedef typename std::vector<const BlockT *>::const_iterator rpot_iterator;
809 
810  rpot_iterator rpot_begin() const { return RPOT.begin(); }
811  rpot_iterator rpot_end() const { return RPOT.end(); }
812 
813  size_t getIndex(const rpot_iterator &I) const { return I - rpot_begin(); }
814 
815  BlockNode getNode(const rpot_iterator &I) const {
816  return BlockNode(getIndex(I));
817  }
818  BlockNode getNode(const BlockT *BB) const { return Nodes.lookup(BB); }
819 
820  const BlockT *getBlock(const BlockNode &Node) const {
821  assert(Node.Index < RPOT.size());
822  return RPOT[Node.Index];
823  }
824 
825  /// \brief Run (and save) a post-order traversal.
826  ///
827  /// Saves a reverse post-order traversal of all the nodes in \a F.
828  void initializeRPOT();
829 
830  /// \brief Initialize loop data.
831  ///
832  /// Build up \a Loops using \a LoopInfo. \a LoopInfo gives us a mapping from
833  /// each block to the deepest loop it's in, but we need the inverse. For each
834  /// loop, we store in reverse post-order its "immediate" members, defined as
835  /// the header, the headers of immediate sub-loops, and all other blocks in
836  /// the loop that are not in sub-loops.
837  void initializeLoops();
838 
839  /// \brief Propagate to a block's successors.
840  ///
841  /// In the context of distributing mass through \c OuterLoop, divide the mass
842  /// currently assigned to \c Node between its successors.
843  ///
844  /// \return \c true unless there's an irreducible backedge.
845  bool propagateMassToSuccessors(LoopData *OuterLoop, const BlockNode &Node);
846 
847  /// \brief Compute mass in a particular loop.
848  ///
849  /// Assign mass to \c Loop's header, and then for each block in \c Loop in
850  /// reverse post-order, distribute mass to its successors. Only visits nodes
851  /// that have not been packaged into sub-loops.
852  ///
853  /// \pre \a computeMassInLoop() has been called for each subloop of \c Loop.
854  /// \return \c true unless there's an irreducible backedge.
855  bool computeMassInLoop(LoopData &Loop);
856 
857  /// \brief Try to compute mass in the top-level function.
858  ///
859  /// Assign mass to the entry block, and then for each block in reverse
860  /// post-order, distribute mass to its successors. Skips nodes that have
861  /// been packaged into loops.
862  ///
863  /// \pre \a computeMassInLoops() has been called.
864  /// \return \c true unless there's an irreducible backedge.
865  bool tryToComputeMassInFunction();
866 
867  /// \brief Compute mass in (and package up) irreducible SCCs.
868  ///
869  /// Find the irreducible SCCs in \c OuterLoop, add them to \a Loops (in front
870  /// of \c Insert), and call \a computeMassInLoop() on each of them.
871  ///
872  /// If \c OuterLoop is \c nullptr, it refers to the top-level function.
873  ///
874  /// \pre \a computeMassInLoop() has been called for each subloop of \c
875  /// OuterLoop.
876  /// \pre \c Insert points at the last loop successfully processed by \a
877  /// computeMassInLoop().
878  /// \pre \c OuterLoop has irreducible SCCs.
879  void computeIrreducibleMass(LoopData *OuterLoop,
880  std::list<LoopData>::iterator Insert);
881 
882  /// \brief Compute mass in all loops.
883  ///
884  /// For each loop bottom-up, call \a computeMassInLoop().
885  ///
886  /// \a computeMassInLoop() aborts (and returns \c false) on loops that
887  /// contain a irreducible sub-SCCs. Use \a computeIrreducibleMass() and then
888  /// re-enter \a computeMassInLoop().
889  ///
890  /// \post \a computeMassInLoop() has returned \c true for every loop.
891  void computeMassInLoops();
892 
893  /// \brief Compute mass in the top-level function.
894  ///
895  /// Uses \a tryToComputeMassInFunction() and \a computeIrreducibleMass() to
896  /// compute mass in the top-level function.
897  ///
898  /// \post \a tryToComputeMassInFunction() has returned \c true.
899  void computeMassInFunction();
900 
901  std::string getBlockName(const BlockNode &Node) const override {
902  return bfi_detail::getBlockName(getBlock(Node));
903  }
904 
905 public:
906  const FunctionT *getFunction() const { return F; }
907 
908  void doFunction(const FunctionT *F, const BranchProbabilityInfoT *BPI,
909  const LoopInfoT *LI);
910  BlockFrequencyInfoImpl() : BPI(nullptr), LI(nullptr), F(nullptr) {}
911 
913  BlockFrequency getBlockFreq(const BlockT *BB) const {
914  return BlockFrequencyInfoImplBase::getBlockFreq(getNode(BB));
915  }
916  Scaled64 getFloatingBlockFreq(const BlockT *BB) const {
918  }
919 
920  /// \brief Print the frequencies for the current function.
921  ///
922  /// Prints the frequencies for the blocks in the current function.
923  ///
924  /// Blocks are printed in the natural iteration order of the function, rather
925  /// than reverse post-order. This provides two advantages: writing -analyze
926  /// tests is easier (since blocks come out in source order), and even
927  /// unreachable blocks are printed.
928  ///
929  /// \a BlockFrequencyInfoImplBase::print() only knows reverse post-order, so
930  /// we need to override it here.
931  raw_ostream &print(raw_ostream &OS) const override;
933 
935  raw_ostream &printBlockFreq(raw_ostream &OS, const BlockT *BB) const {
936  return BlockFrequencyInfoImplBase::printBlockFreq(OS, getNode(BB));
937  }
938 };
939 
940 template <class BT>
942  const BranchProbabilityInfoT *BPI,
943  const LoopInfoT *LI) {
944  // Save the parameters.
945  this->BPI = BPI;
946  this->LI = LI;
947  this->F = F;
948 
949  // Clean up left-over data structures.
951  RPOT.clear();
952  Nodes.clear();
953 
954  // Initialize.
955  DEBUG(dbgs() << "\nblock-frequency: " << F->getName() << "\n================="
956  << std::string(F->getName().size(), '=') << "\n");
957  initializeRPOT();
958  initializeLoops();
959 
960  // Visit loops in post-order to find the local mass distribution, and then do
961  // the full function.
962  computeMassInLoops();
963  computeMassInFunction();
964  unwrapLoops();
965  finalizeMetrics();
966 }
967 
968 template <class BT> void BlockFrequencyInfoImpl<BT>::initializeRPOT() {
969  const BlockT *Entry = F->begin();
970  RPOT.reserve(F->size());
971  std::copy(po_begin(Entry), po_end(Entry), std::back_inserter(RPOT));
972  std::reverse(RPOT.begin(), RPOT.end());
973 
974  assert(RPOT.size() - 1 <= BlockNode::getMaxIndex() &&
975  "More nodes in function than Block Frequency Info supports");
976 
977  DEBUG(dbgs() << "reverse-post-order-traversal\n");
978  for (rpot_iterator I = rpot_begin(), E = rpot_end(); I != E; ++I) {
979  BlockNode Node = getNode(I);
980  DEBUG(dbgs() << " - " << getIndex(I) << ": " << getBlockName(Node) << "\n");
981  Nodes[*I] = Node;
982  }
983 
984  Working.reserve(RPOT.size());
985  for (size_t Index = 0; Index < RPOT.size(); ++Index)
986  Working.emplace_back(Index);
987  Freqs.resize(RPOT.size());
988 }
989 
990 template <class BT> void BlockFrequencyInfoImpl<BT>::initializeLoops() {
991  DEBUG(dbgs() << "loop-detection\n");
992  if (LI->empty())
993  return;
994 
995  // Visit loops top down and assign them an index.
996  std::deque<std::pair<const LoopT *, LoopData *>> Q;
997  for (const LoopT *L : *LI)
998  Q.emplace_back(L, nullptr);
999  while (!Q.empty()) {
1000  const LoopT *Loop = Q.front().first;
1001  LoopData *Parent = Q.front().second;
1002  Q.pop_front();
1003 
1004  BlockNode Header = getNode(Loop->getHeader());
1005  assert(Header.isValid());
1006 
1007  Loops.emplace_back(Parent, Header);
1008  Working[Header.Index].Loop = &Loops.back();
1009  DEBUG(dbgs() << " - loop = " << getBlockName(Header) << "\n");
1010 
1011  for (const LoopT *L : *Loop)
1012  Q.emplace_back(L, &Loops.back());
1013  }
1014 
1015  // Visit nodes in reverse post-order and add them to their deepest containing
1016  // loop.
1017  for (size_t Index = 0; Index < RPOT.size(); ++Index) {
1018  // Loop headers have already been mostly mapped.
1019  if (Working[Index].isLoopHeader()) {
1020  LoopData *ContainingLoop = Working[Index].getContainingLoop();
1021  if (ContainingLoop)
1022  ContainingLoop->Nodes.push_back(Index);
1023  continue;
1024  }
1025 
1026  const LoopT *Loop = LI->getLoopFor(RPOT[Index]);
1027  if (!Loop)
1028  continue;
1029 
1030  // Add this node to its containing loop's member list.
1031  BlockNode Header = getNode(Loop->getHeader());
1032  assert(Header.isValid());
1033  const auto &HeaderData = Working[Header.Index];
1034  assert(HeaderData.isLoopHeader());
1035 
1036  Working[Index].Loop = HeaderData.Loop;
1037  HeaderData.Loop->Nodes.push_back(Index);
1038  DEBUG(dbgs() << " - loop = " << getBlockName(Header)
1039  << ": member = " << getBlockName(Index) << "\n");
1040  }
1041 }
1042 
1043 template <class BT> void BlockFrequencyInfoImpl<BT>::computeMassInLoops() {
1044  // Visit loops with the deepest first, and the top-level loops last.
1045  for (auto L = Loops.rbegin(), E = Loops.rend(); L != E; ++L) {
1046  if (computeMassInLoop(*L))
1047  continue;
1048  auto Next = std::next(L);
1049  computeIrreducibleMass(&*L, L.base());
1050  L = std::prev(Next);
1051  if (computeMassInLoop(*L))
1052  continue;
1053  llvm_unreachable("unhandled irreducible control flow");
1054  }
1055 }
1056 
1057 template <class BT>
1058 bool BlockFrequencyInfoImpl<BT>::computeMassInLoop(LoopData &Loop) {
1059  // Compute mass in loop.
1060  DEBUG(dbgs() << "compute-mass-in-loop: " << getLoopName(Loop) << "\n");
1061 
1062  if (Loop.isIrreducible()) {
1063  BlockMass Remaining = BlockMass::getFull();
1064  for (uint32_t H = 0; H < Loop.NumHeaders; ++H) {
1065  auto &Mass = Working[Loop.Nodes[H].Index].getMass();
1066  Mass = Remaining * BranchProbability(1, Loop.NumHeaders - H);
1067  Remaining -= Mass;
1068  }
1069  for (const BlockNode &M : Loop.Nodes)
1070  if (!propagateMassToSuccessors(&Loop, M))
1071  llvm_unreachable("unhandled irreducible control flow");
1072 
1073  adjustLoopHeaderMass(Loop);
1074  } else {
1075  Working[Loop.getHeader().Index].getMass() = BlockMass::getFull();
1076  if (!propagateMassToSuccessors(&Loop, Loop.getHeader()))
1077  llvm_unreachable("irreducible control flow to loop header!?");
1078  for (const BlockNode &M : Loop.members())
1079  if (!propagateMassToSuccessors(&Loop, M))
1080  // Irreducible backedge.
1081  return false;
1082  }
1083 
1084  computeLoopScale(Loop);
1085  packageLoop(Loop);
1086  return true;
1087 }
1088 
1089 template <class BT>
1090 bool BlockFrequencyInfoImpl<BT>::tryToComputeMassInFunction() {
1091  // Compute mass in function.
1092  DEBUG(dbgs() << "compute-mass-in-function\n");
1093  assert(!Working.empty() && "no blocks in function");
1094  assert(!Working[0].isLoopHeader() && "entry block is a loop header");
1095 
1096  Working[0].getMass() = BlockMass::getFull();
1097  for (rpot_iterator I = rpot_begin(), IE = rpot_end(); I != IE; ++I) {
1098  // Check for nodes that have been packaged.
1099  BlockNode Node = getNode(I);
1100  if (Working[Node.Index].isPackaged())
1101  continue;
1102 
1103  if (!propagateMassToSuccessors(nullptr, Node))
1104  return false;
1105  }
1106  return true;
1107 }
1108 
1109 template <class BT> void BlockFrequencyInfoImpl<BT>::computeMassInFunction() {
1110  if (tryToComputeMassInFunction())
1111  return;
1112  computeIrreducibleMass(nullptr, Loops.begin());
1113  if (tryToComputeMassInFunction())
1114  return;
1115  llvm_unreachable("unhandled irreducible control flow");
1116 }
1117 
1118 /// \note This should be a lambda, but that crashes GCC 4.7.
1119 namespace bfi_detail {
1120 template <class BT> struct BlockEdgesAdder {
1121  typedef BT BlockT;
1124 
1127  : BFI(BFI) {}
1129  const LoopData *OuterLoop) {
1130  const BlockT *BB = BFI.RPOT[Irr.Node.Index];
1131  for (auto I = Successor::child_begin(BB), E = Successor::child_end(BB);
1132  I != E; ++I)
1133  G.addEdge(Irr, BFI.getNode(*I), OuterLoop);
1134  }
1135 };
1136 }
1137 template <class BT>
1138 void BlockFrequencyInfoImpl<BT>::computeIrreducibleMass(
1139  LoopData *OuterLoop, std::list<LoopData>::iterator Insert) {
1140  DEBUG(dbgs() << "analyze-irreducible-in-";
1141  if (OuterLoop) dbgs() << "loop: " << getLoopName(*OuterLoop) << "\n";
1142  else dbgs() << "function\n");
1143 
1144  using namespace bfi_detail;
1145  // Ideally, addBlockEdges() would be declared here as a lambda, but that
1146  // crashes GCC 4.7.
1147  BlockEdgesAdder<BT> addBlockEdges(*this);
1148  IrreducibleGraph G(*this, OuterLoop, addBlockEdges);
1149 
1150  for (auto &L : analyzeIrreducible(G, OuterLoop, Insert))
1151  computeMassInLoop(L);
1152 
1153  if (!OuterLoop)
1154  return;
1155  updateLoopWithIrreducible(*OuterLoop);
1156 }
1157 
1158 template <class BT>
1159 bool
1160 BlockFrequencyInfoImpl<BT>::propagateMassToSuccessors(LoopData *OuterLoop,
1161  const BlockNode &Node) {
1162  DEBUG(dbgs() << " - node: " << getBlockName(Node) << "\n");
1163  // Calculate probability for successors.
1164  Distribution Dist;
1165  if (auto *Loop = Working[Node.Index].getPackagedLoop()) {
1166  assert(Loop != OuterLoop && "Cannot propagate mass in a packaged loop");
1167  if (!addLoopSuccessorsToDist(OuterLoop, *Loop, Dist))
1168  // Irreducible backedge.
1169  return false;
1170  } else {
1171  const BlockT *BB = getBlock(Node);
1172  for (auto SI = Successor::child_begin(BB), SE = Successor::child_end(BB);
1173  SI != SE; ++SI)
1174  // Do not dereference SI, or getEdgeWeight() is linear in the number of
1175  // successors.
1176  if (!addToDist(Dist, OuterLoop, Node, getNode(*SI),
1177  BPI->getEdgeWeight(BB, SI)))
1178  // Irreducible backedge.
1179  return false;
1180  }
1181 
1182  // Distribute mass to successors, saving exit and backedge data in the
1183  // loop header.
1184  distributeMass(Node, OuterLoop, Dist);
1185  return true;
1186 }
1187 
1188 template <class BT>
1190  if (!F)
1191  return OS;
1192  OS << "block-frequency-info: " << F->getName() << "\n";
1193  for (const BlockT &BB : *F)
1194  OS << " - " << bfi_detail::getBlockName(&BB)
1195  << ": float = " << getFloatingBlockFreq(&BB)
1196  << ", int = " << getBlockFreq(&BB).getFrequency() << "\n";
1197 
1198  // Add an extra newline for readability.
1199  OS << "\n";
1200  return OS;
1201 }
1202 
1203 } // end namespace llvm
1204 
1205 #undef DEBUG_TYPE
1206 
1207 #endif
void addNodesInLoop(const BFIBase::LoopData &OuterLoop)
bool IsPackaged
Whether this has been packaged.
bool operator!=(const BlockMass &X) const
BlockMass & operator-=(const BlockMass &X)
Subtract another mass.
LoopData * Loop
The loop this block is inside.
ValueT lookup(const KeyT &Val) const
lookup - Return the entry for the specified key, or a default constructed value if no such entry exis...
Definition: DenseMap.h:159
Various leaf nodes.
Definition: ISDOpcodes.h:60
DominatorTree GraphTraits specialization so the DominatorTree can be iterable by generic graph iterat...
Definition: GraphTraits.h:27
LoopData(LoopData *Parent, It1 FirstHeader, It1 LastHeader, It2 FirstOther, It2 LastOther)
BlockMass operator+(const BlockMass &L, const BlockMass &R)
This provides a very simple, boring adaptor for a begin and end iterator into a range type...
void doFunction(const FunctionT *F, const BranchProbabilityInfoT *BPI, const LoopInfoT *LI)
bool operator>=(const BlockMass &X) const
std::string str() const
str - Get the contents as an std::string.
Definition: StringRef.h:188
SmallVector< std::pair< BlockNode, BlockMass >, 4 > ExitMap
void addLocal(const BlockNode &Node, uint64_t Amount)
bool isADoublePackage() const
Has Loop been packaged up twice?
static const bool value
Definition: type_traits.h:46
F(f)
SmallDenseMap< uint32_t, IrrNode *, 4 > Lookup
IrreducibleGraph(BFIBase &BFI, const BFIBase::LoopData *OuterLoop, BlockEdgesAdder addBlockEdges)
Construct an explicit graph containing irreducible control flow.
const BlockFrequencyInfoImpl< BT > & BFI
raw_ostream & print(raw_ostream &OS) const
StringRef getName() const
Return a constant reference to the value's name.
Definition: Value.cpp:188
void operator()(IrreducibleGraph &G, IrreducibleGraph::IrrNode &Irr, const LoopData *OuterLoop)
Weight(DistType Type, BlockNode TargetNode, uint64_t Amount)
Hexagon Hardware Loops
std::string str() const
Return the twine contents as a std::string.
Definition: Twine.cpp:16
bool operator>(const BlockMass &X) const
virtual ~BlockFrequencyInfoImplBase()
Virtual destructor.
BlockMass & getMass()
Get the appropriate mass for a node.
Twine - A lightweight data structure for efficiently representing the concatenation of temporary valu...
Definition: Twine.h:79
ScaledNumber< uint64_t > toScaled() const
Convert to scaled number.
#define llvm_unreachable(msg)
Marks that the current location is not supposed to be reachable.
Definition: ErrorHandling.h:98
BlockFrequency getBlockFreq(const BlockNode &Node) const
BlockMass & operator+=(const BlockMass &X)
Add another mass.
bool isPackaged() const
Has ContainingLoop been packaged up?
void addEdge(IrrNode &Irr, const BlockNode &Succ, const BFIBase::LoopData *OuterLoop)
void adjustLoopHeaderMass(LoopData &Loop)
Adjust the mass of all headers in an irreducible loop.
raw_ostream & operator<<(raw_ostream &OS, const BlockMass &X)
#define false
Definition: ConvertUTF.c:65
#define G(x, y, z)
Definition: MD5.cpp:52
Graph of irreducible control flow.
raw_ostream & print(raw_ostream &OS) const override
Print the frequencies for the current function.
NodeList::const_iterator members_begin() const
void computeLoopScale(LoopData &Loop)
Compute the loop scale for a loop.
void addBackedge(const BlockNode &Node, uint64_t Amount)
void initialize(const BFIBase::LoopData *OuterLoop, BlockEdgesAdder addBlockEdges)
BlockNode getResolvedNode() const
Resolve a node to its representative.
bool addToDist(Distribution &Dist, const LoopData *OuterLoop, const BlockNode &Pred, const BlockNode &Succ, uint64_t Weight)
Add an edge to the distribution.
#define P(N)
std::vector< FrequencyData > Freqs
Data about each block. This is used downstream.
iterator_range< std::list< LoopData >::iterator > analyzeIrreducible(const bfi_detail::IrreducibleGraph &G, LoopData *OuterLoop, std::list< LoopData >::iterator Insert)
Analyze irreducible SCCs.
LLVM Basic Block Representation.
Definition: BasicBlock.h:65
The instances of the Type class are immutable: once they are created, they are never changed...
Definition: Type.h:45
std::deque< const IrrNode * >::const_iterator iterator
std::string getLoopName(const LoopData &Loop) const
#define H(x, y, z)
Definition: MD5.cpp:53
BlockMass & operator*=(const BranchProbability &P)
Distribution of unscaled probability weight.
static GCMetadataPrinterRegistry::Add< ErlangGCPrinter > X("erlang","erlang-compatible garbage collector")
po_iterator< T > po_end(const T &G)
Scaled64 getFloatingBlockFreq(const BlockNode &Node) const
raw_ostream & printBlockFreq(raw_ostream &OS, const BlockNode &Node) const
BlockMass Mass
Mass distribution from the entry block.
iterator_range< NodeList::const_iterator > members() const
bool isHeader(const BlockNode &Node) const
BlockEdgesAdder(const BlockFrequencyInfoImpl< BT > &BFI)
BlockMass operator-(const BlockMass &L, const BlockMass &R)
Scaled64 getFloatingBlockFreq(const BlockT *BB) const
bool operator==(const BlockMass &X) const
void addExit(const BlockNode &Node, uint64_t Amount)
BlockFrequencyInfoImplBase::LoopData LoopData
iterator_range< T > make_range(T x, T y)
Convenience function for iterating over sub-ranges.
isPodLike - This is a type trait that is used to determine whether a given type can be copied around ...
Definition: ArrayRef.h:365
BlockMass operator*(const BlockMass &L, const BranchProbability &R)
ExitMap Exits
Successor edges (and weights).
This is a 'vector' (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:861
block Branch Probability Basic Block static false std::string getBlockName(MachineBasicBlock *BB)
Helper to print the name of a MBB.
virtual std::string getBlockName(const BlockNode &Node) const
std::list< LoopData > Loops
Indexed information about loops.
raw_ostream & dbgs()
dbgs() - This returns a reference to a raw_ostream for debugging messages.
Definition: Debug.cpp:123
A range adaptor for a pair of iterators.
std::string getBlockName(const BlockT *BB)
Get the name of a MachineBasicBlock.
void updateLoopWithIrreducible(LoopData &OuterLoop)
Update a loop after packaging irreducible SCCs inside of it.
const FunctionT * getFunction() const
BlockFrequency getBlockFreq(const BlockT *BB) const
LoopData(LoopData *Parent, const BlockNode &Header)
iterator insert(iterator I, T &&Elt)
Definition: SmallVector.h:481
NodeList::const_iterator members_end() const
Analysis pass providing branch probability information.
uint64_t scale(uint64_t Num) const
Scale a large integer.
bool operator<=(const BlockMass &X) const
void addEdges(const BlockNode &Node, const BFIBase::LoopData *OuterLoop, BlockEdgesAdder addBlockEdges)
void packageLoop(LoopData &Loop)
Package up a loop.
bool isAPackage() const
Has Loop been packaged up?
#define I(x, y, z)
Definition: MD5.cpp:54
#define N
virtual raw_ostream & print(raw_ostream &OS) const
raw_ostream & printBlockFreq(raw_ostream &OS, const BlockT *BB) const
void distributeMass(const BlockNode &Source, LoopData *OuterLoop, Distribution &Dist)
Distribute mass according to a distribution.
NodeList Nodes
Header and the members of the loop.
std::vector< WorkingData > Working
Loop data: see initializeLoops().
HeaderMassList BackedgeMass
Mass returned to each loop header.
This class implements an extremely fast bulk output stream that can only output to a stream...
Definition: raw_ostream.h:38
#define DEBUG(X)
Definition: Debug.h:92
bool operator<(const BlockMass &X) const
Shared implementation for block frequency analysis.
Base class for BlockFrequencyInfoImpl.
bool addLoopSuccessorsToDist(const LoopData *OuterLoop, LoopData &Loop, Distribution &Dist)
Add all edges out of a packaged loop to the distribution.
GraphTraits< const BlockT * > Successor
HeaderMassList::difference_type getHeaderIndex(const BlockNode &B)
LoopData & getLoopPackage(const BlockNode &Head)
po_iterator< T > po_begin(const T &G)
void finalizeMetrics()
Finalize frequency metrics.
WeightList Weights
Individual successor weights.
void resize(size_type N)
Definition: SmallVector.h:376