LCOV - code coverage report
Current view: top level - include/llvm/Analysis - BlockFrequencyInfoImpl.h (source / functions) Hit Total Coverage
Test: llvm-toolchain.info Lines: 258 319 80.9 %
Date: 2018-02-21 17:27:13 Functions: 54 72 75.0 %
Legend: Lines: hit not hit

          Line data    Source code
       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"
      19             : #include "llvm/ADT/DenseSet.h"
      20             : #include "llvm/ADT/GraphTraits.h"
      21             : #include "llvm/ADT/Optional.h"
      22             : #include "llvm/ADT/PostOrderIterator.h"
      23             : #include "llvm/ADT/SmallVector.h"
      24             : #include "llvm/ADT/SparseBitVector.h"
      25             : #include "llvm/ADT/Twine.h"
      26             : #include "llvm/ADT/iterator_range.h"
      27             : #include "llvm/IR/BasicBlock.h"
      28             : #include "llvm/Support/BlockFrequency.h"
      29             : #include "llvm/Support/BranchProbability.h"
      30             : #include "llvm/Support/DOTGraphTraits.h"
      31             : #include "llvm/Support/Debug.h"
      32             : #include "llvm/Support/ErrorHandling.h"
      33             : #include "llvm/Support/Format.h"
      34             : #include "llvm/Support/ScaledNumber.h"
      35             : #include "llvm/Support/raw_ostream.h"
      36             : #include <algorithm>
      37             : #include <cassert>
      38             : #include <cstddef>
      39             : #include <cstdint>
      40             : #include <deque>
      41             : #include <iterator>
      42             : #include <limits>
      43             : #include <list>
      44             : #include <string>
      45             : #include <utility>
      46             : #include <vector>
      47             : 
      48             : #define DEBUG_TYPE "block-freq"
      49             : 
      50             : namespace llvm {
      51             : 
      52             : class BranchProbabilityInfo;
      53             : class Function;
      54             : class Loop;
      55             : class LoopInfo;
      56             : class MachineBasicBlock;
      57             : class MachineBranchProbabilityInfo;
      58             : class MachineFunction;
      59             : class MachineLoop;
      60             : class MachineLoopInfo;
      61             : 
      62             : namespace bfi_detail {
      63             : 
      64             : struct IrreducibleGraph;
      65             : 
      66             : // This is part of a workaround for a GCC 4.7 crash on lambdas.
      67             : template <class BT> struct BlockEdgesAdder;
      68             : 
      69             : /// \brief Mass of a block.
      70             : ///
      71             : /// This class implements a sort of fixed-point fraction always between 0.0 and
      72             : /// 1.0.  getMass() == std::numeric_limits<uint64_t>::max() indicates a value of
      73             : /// 1.0.
      74             : ///
      75             : /// Masses can be added and subtracted.  Simple saturation arithmetic is used,
      76             : /// so arithmetic operations never overflow or underflow.
      77             : ///
      78             : /// Masses can be multiplied.  Multiplication treats full mass as 1.0 and uses
      79             : /// an inexpensive floating-point algorithm that's off-by-one (almost, but not
      80             : /// quite, maximum precision).
      81             : ///
      82             : /// Masses can be scaled by \a BranchProbability at maximum precision.
      83             : class BlockMass {
      84             :   uint64_t Mass = 0;
      85             : 
      86             : public:
      87     5116687 :   BlockMass() = default;
      88             :   explicit BlockMass(uint64_t Mass) : Mass(Mass) {}
      89             : 
      90             :   static BlockMass getEmpty() { return BlockMass(); }
      91             : 
      92             :   static BlockMass getFull() {
      93             :     return BlockMass(std::numeric_limits<uint64_t>::max());
      94             :   }
      95             : 
      96      141042 :   uint64_t getMass() const { return Mass; }
      97             : 
      98     2612634 :   bool isFull() const { return Mass == std::numeric_limits<uint64_t>::max(); }
      99             :   bool isEmpty() const { return !Mass; }
     100             : 
     101             :   bool operator!() const { return isEmpty(); }
     102             : 
     103             :   /// \brief Add another mass.
     104             :   ///
     105             :   /// Adds another mass, saturating at \a isFull() rather than overflowing.
     106             :   BlockMass &operator+=(BlockMass X) {
     107     2052843 :     uint64_t Sum = Mass + X.Mass;
     108     2052843 :     Mass = Sum < Mass ? std::numeric_limits<uint64_t>::max() : Sum;
     109             :     return *this;
     110             :   }
     111             : 
     112             :   /// \brief Subtract another mass.
     113             :   ///
     114             :   /// Subtracts another mass, saturating at \a isEmpty() rather than
     115             :   /// undeflowing.
     116             :   BlockMass &operator-=(BlockMass X) {
     117     2193902 :     uint64_t Diff = Mass - X.Mass;
     118     2136727 :     Mass = Diff > Mass ? 0 : Diff;
     119             :     return *this;
     120             :   }
     121             : 
     122             :   BlockMass &operator*=(BranchProbability P) {
     123     2136727 :     Mass = P.scale(Mass);
     124             :     return *this;
     125             :   }
     126             : 
     127             :   bool operator==(BlockMass X) const { return Mass == X.Mass; }
     128             :   bool operator!=(BlockMass X) const { return Mass != X.Mass; }
     129             :   bool operator<=(BlockMass X) const { return Mass <= X.Mass; }
     130             :   bool operator>=(BlockMass X) const { return Mass >= X.Mass; }
     131             :   bool operator<(BlockMass X) const { return Mass < X.Mass; }
     132             :   bool operator>(BlockMass X) const { return Mass > X.Mass; }
     133             : 
     134             :   /// \brief Convert to scaled number.
     135             :   ///
     136             :   /// Convert to \a ScaledNumber.  \a isFull() gives 1.0, while \a isEmpty()
     137             :   /// gives slightly above 0.0.
     138             :   ScaledNumber<uint64_t> toScaled() const;
     139             : 
     140             :   void dump() const;
     141             :   raw_ostream &print(raw_ostream &OS) const;
     142             : };
     143             : 
     144             : inline BlockMass operator+(BlockMass L, BlockMass R) {
     145             :   return BlockMass(L) += R;
     146             : }
     147             : inline BlockMass operator-(BlockMass L, BlockMass R) {
     148             :   return BlockMass(L) -= R;
     149             : }
     150             : inline BlockMass operator*(BlockMass L, BranchProbability R) {
     151             :   return BlockMass(L) *= R;
     152             : }
     153             : inline BlockMass operator*(BranchProbability L, BlockMass R) {
     154             :   return BlockMass(R) *= L;
     155             : }
     156             : 
     157             : inline raw_ostream &operator<<(raw_ostream &OS, BlockMass X) {
     158             :   return X.print(OS);
     159             : }
     160             : 
     161             : } // end namespace bfi_detail
     162             : 
     163             : template <> struct isPodLike<bfi_detail::BlockMass> {
     164             :   static const bool value = true;
     165             : };
     166             : 
     167             : /// \brief Base class for BlockFrequencyInfoImpl
     168             : ///
     169             : /// BlockFrequencyInfoImplBase has supporting data structures and some
     170             : /// algorithms for BlockFrequencyInfoImplBase.  Only algorithms that depend on
     171             : /// the block type (or that call such algorithms) are skipped here.
     172             : ///
     173             : /// Nevertheless, the majority of the overall algorithm documention lives with
     174             : /// BlockFrequencyInfoImpl.  See there for details.
     175             : class BlockFrequencyInfoImplBase {
     176             : public:
     177             :   using Scaled64 = ScaledNumber<uint64_t>;
     178             :   using BlockMass = bfi_detail::BlockMass;
     179             : 
     180             :   /// \brief Representative of a block.
     181             :   ///
     182             :   /// This is a simple wrapper around an index into the reverse-post-order
     183             :   /// traversal of the blocks.
     184             :   ///
     185             :   /// Unlike a block pointer, its order has meaning (location in the
     186             :   /// topological sort) and it's class is the same regardless of block type.
     187             :   struct BlockNode {
     188             :     using IndexType = uint32_t;
     189             : 
     190             :     IndexType Index = std::numeric_limits<uint32_t>::max();
     191             : 
     192     2502299 :     BlockNode() = default;
     193      215101 :     BlockNode(IndexType Index) : Index(Index) {}
     194             : 
     195     2892248 :     bool operator==(const BlockNode &X) const { return Index == X.Index; }
     196     2504468 :     bool operator!=(const BlockNode &X) const { return Index != X.Index; }
     197             :     bool operator<=(const BlockNode &X) const { return Index <= X.Index; }
     198             :     bool operator>=(const BlockNode &X) const { return Index >= X.Index; }
     199     3220817 :     bool operator<(const BlockNode &X) const { return Index < X.Index; }
     200             :     bool operator>(const BlockNode &X) const { return Index > X.Index; }
     201             : 
     202     6598407 :     bool isValid() const { return Index <= getMaxIndex(); }
     203             : 
     204             :     static size_t getMaxIndex() {
     205             :        return std::numeric_limits<uint32_t>::max() - 1;
     206             :     }
     207             :   };
     208             : 
     209             :   /// \brief Stats about a block itself.
     210             :   struct FrequencyData {
     211             :     Scaled64 Scaled;
     212             :     uint64_t Integer;
     213             :   };
     214             : 
     215             :   /// \brief Data about a loop.
     216             :   ///
     217             :   /// Contains the data necessary to represent a loop as a pseudo-node once it's
     218             :   /// packaged.
     219      114350 :   struct LoopData {
     220             :     using ExitMap = SmallVector<std::pair<BlockNode, BlockMass>, 4>;
     221             :     using NodeList = SmallVector<BlockNode, 4>;
     222             :     using HeaderMassList = SmallVector<BlockMass, 1>;
     223             : 
     224             :     LoopData *Parent;            ///< The parent loop.
     225             :     bool IsPackaged = false;     ///< Whether this has been packaged.
     226             :     uint32_t NumHeaders = 1;     ///< Number of headers.
     227             :     ExitMap Exits;               ///< Successor edges (and weights).
     228             :     NodeList Nodes;              ///< Header and the members of the loop.
     229             :     HeaderMassList BackedgeMass; ///< Mass returned to each loop header.
     230             :     BlockMass Mass;
     231             :     Scaled64 Scale;
     232             : 
     233       57016 :     LoopData(LoopData *Parent, const BlockNode &Header)
     234      228064 :       : Parent(Parent), Nodes(1, Header), BackedgeMass(1) {}
     235             : 
     236             :     template <class It1, class It2>
     237         159 :     LoopData(LoopData *Parent, It1 FirstHeader, It1 LastHeader, It2 FirstOther,
     238             :              It2 LastOther)
     239         159 :         : Parent(Parent), Nodes(FirstHeader, LastHeader) {
     240         159 :       NumHeaders = Nodes.size();
     241         159 :       Nodes.insert(Nodes.end(), FirstOther, LastOther);
     242         159 :       BackedgeMass.resize(NumHeaders);
     243         159 :     }
     244             : 
     245     2119951 :     bool isHeader(const BlockNode &Node) const {
     246     2119951 :       if (isIrreducible())
     247       14297 :         return std::binary_search(Nodes.begin(), Nodes.begin() + NumHeaders,
     248             :                                   Node);
     249     2105654 :       return Node == Nodes[0];
     250             :     }
     251             : 
     252      518408 :     BlockNode getHeader() const { return Nodes[0]; }
     253             :     bool isIrreducible() const { return NumHeaders > 1; }
     254             : 
     255       61173 :     HeaderMassList::difference_type getHeaderIndex(const BlockNode &B) {
     256             :       assert(isHeader(B) && "this is only valid on loop header blocks");
     257       61173 :       if (isIrreducible())
     258        5592 :         return std::lower_bound(Nodes.begin(), Nodes.begin() + NumHeaders, B) -
     259        2796 :                Nodes.begin();
     260             :       return 0;
     261             :     }
     262             : 
     263             :     NodeList::const_iterator members_begin() const {
     264       57061 :       return Nodes.begin() + NumHeaders;
     265             :     }
     266             : 
     267             :     NodeList::const_iterator members_end() const { return Nodes.end(); }
     268             :     iterator_range<NodeList::const_iterator> members() const {
     269             :       return make_range(members_begin(), members_end());
     270             :     }
     271             :   };
     272             : 
     273             :   /// \brief Index of loop information.
     274             :   struct WorkingData {
     275             :     BlockNode Node;           ///< This node.
     276             :     LoopData *Loop = nullptr; ///< The loop this block is inside.
     277             :     BlockMass Mass;           ///< Mass distribution from the entry block.
     278             : 
     279     2500495 :     WorkingData(const BlockNode &Node) : Node(Node) {}
     280             : 
     281     9106616 :     bool isLoopHeader() const { return Loop && Loop->isHeader(Node); }
     282             : 
     283      232180 :     bool isDoubleLoopHeader() const {
     284      232804 :       return isLoopHeader() && Loop->Parent && Loop->Parent->isIrreducible() &&
     285      232804 :              Loop->Parent->isHeader(Node);
     286             :     }
     287             : 
     288     2149369 :     LoopData *getContainingLoop() const {
     289             :       if (!isLoopHeader())
     290             :         return Loop;
     291      116762 :       if (!isDoubleLoopHeader())
     292      116634 :         return Loop->Parent;
     293         128 :       return Loop->Parent->Parent;
     294             :     }
     295             : 
     296             :     /// \brief Resolve a node to its representative.
     297             :     ///
     298             :     /// Get the node currently representing Node, which could be a containing
     299             :     /// loop.
     300             :     ///
     301             :     /// This function should only be called when distributing mass.  As long as
     302             :     /// there are no irreducible edges to Node, then it will have complexity
     303             :     /// O(1) in this context.
     304             :     ///
     305             :     /// In general, the complexity is O(L), where L is the number of loop
     306             :     /// headers Node has been packaged into.  Since this method is called in
     307             :     /// the context of distributing mass, L will be the number of loop headers
     308             :     /// an early exit edge jumps out of.
     309             :     BlockNode getResolvedNode() const {
     310     4657504 :       auto L = getPackagedLoop();
     311     4336694 :       return L ? L->getHeader() : Node;
     312             :     }
     313             : 
     314             :     LoopData *getPackagedLoop() const {
     315     7492325 :       if (!Loop || !Loop->IsPackaged)
     316             :         return nullptr;
     317             :       auto L = Loop;
     318      441346 :       while (L->Parent && L->Parent->IsPackaged)
     319             :         L = L->Parent;
     320             :       return L;
     321             :     }
     322             : 
     323             :     /// \brief Get the appropriate mass for a node.
     324             :     ///
     325             :     /// Get appropriate mass for Node.  If Node is a loop-header (whose loop
     326             :     /// has been packaged), returns the mass of its pseudo-node.  If it's a
     327             :     /// node inside a packaged loop, it returns the loop's mass.
     328     5614553 :     BlockMass &getMass() {
     329     5614553 :       if (!isAPackage())
     330     5499134 :         return Mass;
     331             :       if (!isADoublePackage())
     332      115359 :         return Loop->Mass;
     333          59 :       return Loop->Parent->Mass;
     334             :     }
     335             : 
     336             :     /// \brief Has ContainingLoop been packaged up?
     337             :     bool isPackaged() const { return getResolvedNode() != Node; }
     338             : 
     339             :     /// \brief Has Loop been packaged up?
     340     6182098 :     bool isAPackage() const { return isLoopHeader() && Loop->IsPackaged; }
     341             : 
     342             :     /// \brief Has Loop been packaged up twice?
     343             :     bool isADoublePackage() const {
     344      115418 :       return isDoubleLoopHeader() && Loop->Parent->IsPackaged;
     345             :     }
     346             :   };
     347             : 
     348             :   /// \brief Unscaled probability weight.
     349             :   ///
     350             :   /// Probability weight for an edge in the graph (including the
     351             :   /// successor/target node).
     352             :   ///
     353             :   /// All edges in the original function are 32-bit.  However, exit edges from
     354             :   /// loop packages are taken from 64-bit exit masses, so we need 64-bits of
     355             :   /// space in general.
     356             :   ///
     357             :   /// In addition to the raw weight amount, Weight stores the type of the edge
     358             :   /// in the current context (i.e., the context of the loop being processed).
     359             :   /// Is this a local edge within the loop, an exit from the loop, or a
     360             :   /// backedge to the loop header?
     361             :   struct Weight {
     362             :     enum DistType { Local, Exit, Backedge };
     363             :     DistType Type = Local;
     364             :     BlockNode TargetNode;
     365             :     uint64_t Amount = 0;
     366             : 
     367             :     Weight() = default;
     368             :     Weight(DistType Type, BlockNode TargetNode, uint64_t Amount)
     369     2154004 :         : Type(Type), TargetNode(TargetNode), Amount(Amount) {}
     370             :   };
     371             : 
     372             :   /// \brief Distribution of unscaled probability weight.
     373             :   ///
     374             :   /// Distribution of unscaled probability weight to a set of successors.
     375             :   ///
     376             :   /// This class collates the successor edge weights for later processing.
     377             :   ///
     378             :   /// \a DidOverflow indicates whether \a Total did overflow while adding to
     379             :   /// the distribution.  It should never overflow twice.
     380           3 :   struct Distribution {
     381             :     using WeightList = SmallVector<Weight, 4>;
     382             : 
     383             :     WeightList Weights;       ///< Individual successor weights.
     384             :     uint64_t Total = 0;       ///< Sum of all weights.
     385             :     bool DidOverflow = false; ///< Whether \a Total did overflow.
     386             : 
     387     2559177 :     Distribution() = default;
     388             : 
     389             :     void addLocal(const BlockNode &Node, uint64_t Amount) {
     390     1951377 :       add(Node, Amount, Weight::Local);
     391             :     }
     392             : 
     393             :     void addExit(const BlockNode &Node, uint64_t Amount) {
     394      141944 :       add(Node, Amount, Weight::Exit);
     395             :     }
     396             : 
     397             :     void addBackedge(const BlockNode &Node, uint64_t Amount) {
     398       60683 :       add(Node, Amount, Weight::Backedge);
     399             :     }
     400             : 
     401             :     /// \brief Normalize the distribution.
     402             :     ///
     403             :     /// Combines multiple edges to the same \a Weight::TargetNode and scales
     404             :     /// down so that \a Total fits into 32-bits.
     405             :     ///
     406             :     /// This is linear in the size of \a Weights.  For the vast majority of
     407             :     /// cases, adjacent edge weights are combined by sorting WeightList and
     408             :     /// combining adjacent weights.  However, for very large edge lists an
     409             :     /// auxiliary hash table is used.
     410             :     void normalize();
     411             : 
     412             :   private:
     413             :     void add(const BlockNode &Node, uint64_t Amount, Weight::DistType Type);
     414             :   };
     415             : 
     416             :   /// \brief Data about each block.  This is used downstream.
     417             :   std::vector<FrequencyData> Freqs;
     418             : 
     419             :   /// \brief Whether each block is an irreducible loop header.
     420             :   /// This is used downstream.
     421             :   SparseBitVector<> IsIrrLoopHeader;
     422             : 
     423             :   /// \brief Loop data: see initializeLoops().
     424             :   std::vector<WorkingData> Working;
     425             : 
     426             :   /// \brief Indexed information about loops.
     427             :   std::list<LoopData> Loops;
     428             : 
     429             :   /// \brief Virtual destructor.
     430             :   ///
     431             :   /// Need a virtual destructor to mask the compiler warning about
     432             :   /// getBlockName().
     433     2119662 :   virtual ~BlockFrequencyInfoImplBase() = default;
     434             : 
     435             :   /// \brief Add all edges out of a packaged loop to the distribution.
     436             :   ///
     437             :   /// Adds all edges from LocalLoopHead to Dist.  Calls addToDist() to add each
     438             :   /// successor edge.
     439             :   ///
     440             :   /// \return \c true unless there's an irreducible backedge.
     441             :   bool addLoopSuccessorsToDist(const LoopData *OuterLoop, LoopData &Loop,
     442             :                                Distribution &Dist);
     443             : 
     444             :   /// \brief Add an edge to the distribution.
     445             :   ///
     446             :   /// Adds an edge to Succ to Dist.  If \c LoopHead.isValid(), then whether the
     447             :   /// edge is local/exit/backedge is in the context of LoopHead.  Otherwise,
     448             :   /// every edge should be a local edge (since all the loops are packaged up).
     449             :   ///
     450             :   /// \return \c true unless aborted due to an irreducible backedge.
     451             :   bool addToDist(Distribution &Dist, const LoopData *OuterLoop,
     452             :                  const BlockNode &Pred, const BlockNode &Succ, uint64_t Weight);
     453             : 
     454             :   LoopData &getLoopPackage(const BlockNode &Head) {
     455             :     assert(Head.Index < Working.size());
     456             :     assert(Working[Head.Index].isLoopHeader());
     457             :     return *Working[Head.Index].Loop;
     458             :   }
     459             : 
     460             :   /// \brief Analyze irreducible SCCs.
     461             :   ///
     462             :   /// Separate irreducible SCCs from \c G, which is an explict graph of \c
     463             :   /// OuterLoop (or the top-level function, if \c OuterLoop is \c nullptr).
     464             :   /// Insert them into \a Loops before \c Insert.
     465             :   ///
     466             :   /// \return the \c LoopData nodes representing the irreducible SCCs.
     467             :   iterator_range<std::list<LoopData>::iterator>
     468             :   analyzeIrreducible(const bfi_detail::IrreducibleGraph &G, LoopData *OuterLoop,
     469             :                      std::list<LoopData>::iterator Insert);
     470             : 
     471             :   /// \brief Update a loop after packaging irreducible SCCs inside of it.
     472             :   ///
     473             :   /// Update \c OuterLoop.  Before finding irreducible control flow, it was
     474             :   /// partway through \a computeMassInLoop(), so \a LoopData::Exits and \a
     475             :   /// LoopData::BackedgeMass need to be reset.  Also, nodes that were packaged
     476             :   /// up need to be removed from \a OuterLoop::Nodes.
     477             :   void updateLoopWithIrreducible(LoopData &OuterLoop);
     478             : 
     479             :   /// \brief Distribute mass according to a distribution.
     480             :   ///
     481             :   /// Distributes the mass in Source according to Dist.  If LoopHead.isValid(),
     482             :   /// backedges and exits are stored in its entry in Loops.
     483             :   ///
     484             :   /// Mass is distributed in parallel from two copies of the source mass.
     485             :   void distributeMass(const BlockNode &Source, LoopData *OuterLoop,
     486             :                       Distribution &Dist);
     487             : 
     488             :   /// \brief Compute the loop scale for a loop.
     489             :   void computeLoopScale(LoopData &Loop);
     490             : 
     491             :   /// Adjust the mass of all headers in an irreducible loop.
     492             :   ///
     493             :   /// Initially, irreducible loops are assumed to distribute their mass
     494             :   /// equally among its headers. This can lead to wrong frequency estimates
     495             :   /// since some headers may be executed more frequently than others.
     496             :   ///
     497             :   /// This adjusts header mass distribution so it matches the weights of
     498             :   /// the backedges going into each of the loop headers.
     499             :   void adjustLoopHeaderMass(LoopData &Loop);
     500             : 
     501             :   void distributeIrrLoopHeaderMass(Distribution &Dist);
     502             : 
     503             :   /// \brief Package up a loop.
     504             :   void packageLoop(LoopData &Loop);
     505             : 
     506             :   /// \brief Unwrap loops.
     507             :   void unwrapLoops();
     508             : 
     509             :   /// \brief Finalize frequency metrics.
     510             :   ///
     511             :   /// Calculates final frequencies and cleans up no-longer-needed data
     512             :   /// structures.
     513             :   void finalizeMetrics();
     514             : 
     515             :   /// \brief Clear all memory.
     516             :   void clear();
     517             : 
     518             :   virtual std::string getBlockName(const BlockNode &Node) const;
     519             :   std::string getLoopName(const LoopData &Loop) const;
     520             : 
     521           0 :   virtual raw_ostream &print(raw_ostream &OS) const { return OS; }
     522             :   void dump() const { print(dbgs()); }
     523             : 
     524             :   Scaled64 getFloatingBlockFreq(const BlockNode &Node) const;
     525             : 
     526             :   BlockFrequency getBlockFreq(const BlockNode &Node) const;
     527             :   Optional<uint64_t> getBlockProfileCount(const Function &F,
     528             :                                           const BlockNode &Node) const;
     529             :   Optional<uint64_t> getProfileCountFromFreq(const Function &F,
     530             :                                              uint64_t Freq) const;
     531             :   bool isIrrLoopHeader(const BlockNode &Node);
     532             : 
     533             :   void setBlockFreq(const BlockNode &Node, uint64_t Freq);
     534             : 
     535             :   raw_ostream &printBlockFreq(raw_ostream &OS, const BlockNode &Node) const;
     536             :   raw_ostream &printBlockFreq(raw_ostream &OS,
     537             :                               const BlockFrequency &Freq) const;
     538             : 
     539             :   uint64_t getEntryFreq() const {
     540             :     assert(!Freqs.empty());
     541     4442996 :     return Freqs[0].Integer;
     542             :   }
     543             : };
     544             : 
     545             : namespace bfi_detail {
     546             : 
     547             : template <class BlockT> struct TypeMap {};
     548             : template <> struct TypeMap<BasicBlock> {
     549             :   using BlockT = BasicBlock;
     550             :   using FunctionT = Function;
     551             :   using BranchProbabilityInfoT = BranchProbabilityInfo;
     552             :   using LoopT = Loop;
     553             :   using LoopInfoT = LoopInfo;
     554             : };
     555             : template <> struct TypeMap<MachineBasicBlock> {
     556             :   using BlockT = MachineBasicBlock;
     557             :   using FunctionT = MachineFunction;
     558             :   using BranchProbabilityInfoT = MachineBranchProbabilityInfo;
     559             :   using LoopT = MachineLoop;
     560             :   using LoopInfoT = MachineLoopInfo;
     561             : };
     562             : 
     563             : /// \brief Get the name of a MachineBasicBlock.
     564             : ///
     565             : /// Get the name of a MachineBasicBlock.  It's templated so that including from
     566             : /// CodeGen is unnecessary (that would be a layering issue).
     567             : ///
     568             : /// This is used mainly for debug output.  The name is similar to
     569             : /// MachineBasicBlock::getFullName(), but skips the name of the function.
     570           0 : template <class BlockT> std::string getBlockName(const BlockT *BB) {
     571             :   assert(BB && "Unexpected nullptr");
     572           0 :   auto MachineName = "BB" + Twine(BB->getNumber());
     573           0 :   if (BB->getBasicBlock())
     574           0 :     return (MachineName + "[" + BB->getName() + "]").str();
     575           0 :   return MachineName.str();
     576             : }
     577             : /// \brief Get the name of a BasicBlock.
     578         522 : template <> inline std::string getBlockName(const BasicBlock *BB) {
     579             :   assert(BB && "Unexpected nullptr");
     580        1044 :   return BB->getName().str();
     581             : }
     582             : 
     583             : /// \brief Graph of irreducible control flow.
     584             : ///
     585             : /// This graph is used for determining the SCCs in a loop (or top-level
     586             : /// function) that has irreducible control flow.
     587             : ///
     588             : /// During the block frequency algorithm, the local graphs are defined in a
     589             : /// light-weight way, deferring to the \a BasicBlock or \a MachineBasicBlock
     590             : /// graphs for most edges, but getting others from \a LoopData::ExitMap.  The
     591             : /// latter only has successor information.
     592             : ///
     593             : /// \a IrreducibleGraph makes this graph explicit.  It's in a form that can use
     594             : /// \a GraphTraits (so that \a analyzeIrreducible() can use \a scc_iterator),
     595             : /// and it explicitly lists predecessors and successors.  The initialization
     596             : /// that relies on \c MachineBasicBlock is defined in the header.
     597         312 : struct IrreducibleGraph {
     598             :   using BFIBase = BlockFrequencyInfoImplBase;
     599             : 
     600             :   BFIBase &BFI;
     601             : 
     602             :   using BlockNode = BFIBase::BlockNode;
     603        9209 :   struct IrrNode {
     604             :     BlockNode Node;
     605             :     unsigned NumIn = 0;
     606             :     std::deque<const IrrNode *> Edges;
     607             : 
     608        2991 :     IrrNode(const BlockNode &Node) : Node(Node) {}
     609             : 
     610             :     using iterator = std::deque<const IrrNode *>::const_iterator;
     611             : 
     612             :     iterator pred_begin() const { return Edges.begin(); }
     613       12654 :     iterator succ_begin() const { return Edges.begin() + NumIn; }
     614        3336 :     iterator pred_end() const { return succ_begin(); }
     615             :     iterator succ_end() const { return Edges.end(); }
     616             :   };
     617             :   BlockNode Start;
     618             :   const IrrNode *StartIrr = nullptr;
     619             :   std::vector<IrrNode> Nodes;
     620             :   SmallDenseMap<uint32_t, IrrNode *, 4> Lookup;
     621             : 
     622             :   /// \brief Construct an explicit graph containing irreducible control flow.
     623             :   ///
     624             :   /// Construct an explicit graph of the control flow in \c OuterLoop (or the
     625             :   /// top-level function, if \c OuterLoop is \c nullptr).  Uses \c
     626             :   /// addBlockEdges to add block successors that have not been packaged into
     627             :   /// loops.
     628             :   ///
     629             :   /// \a BlockFrequencyInfoImpl::computeIrreducibleMass() is the only expected
     630             :   /// user of this.
     631             :   template <class BlockEdgesAdder>
     632         156 :   IrreducibleGraph(BFIBase &BFI, const BFIBase::LoopData *OuterLoop,
     633         468 :                    BlockEdgesAdder addBlockEdges) : BFI(BFI) {
     634         156 :     initialize(OuterLoop, addBlockEdges);
     635         156 :   }
     636             : 
     637             :   template <class BlockEdgesAdder>
     638             :   void initialize(const BFIBase::LoopData *OuterLoop,
     639             :                   BlockEdgesAdder addBlockEdges);
     640             :   void addNodesInLoop(const BFIBase::LoopData &OuterLoop);
     641             :   void addNodesInFunction();
     642             : 
     643        2991 :   void addNode(const BlockNode &Node) {
     644        2991 :     Nodes.emplace_back(Node);
     645        5982 :     BFI.Working[Node.Index].getMass() = BlockMass::getEmpty();
     646        2991 :   }
     647             : 
     648             :   void indexNodes();
     649             :   template <class BlockEdgesAdder>
     650             :   void addEdges(const BlockNode &Node, const BFIBase::LoopData *OuterLoop,
     651             :                 BlockEdgesAdder addBlockEdges);
     652             :   void addEdge(IrrNode &Irr, const BlockNode &Succ,
     653             :                const BFIBase::LoopData *OuterLoop);
     654             : };
     655             : 
     656             : template <class BlockEdgesAdder>
     657         156 : void IrreducibleGraph::initialize(const BFIBase::LoopData *OuterLoop,
     658             :                                   BlockEdgesAdder addBlockEdges) {
     659         156 :   if (OuterLoop) {
     660          45 :     addNodesInLoop(*OuterLoop);
     661        1295 :     for (auto N : OuterLoop->Nodes)
     662         625 :       addEdges(N, OuterLoop, addBlockEdges);
     663             :   } else {
     664         111 :     addNodesInFunction();
     665        7827 :     for (uint32_t Index = 0; Index < BFI.Working.size(); ++Index)
     666        2535 :       addEdges(Index, OuterLoop, addBlockEdges);
     667             :   }
     668         312 :   StartIrr = Lookup[Start.Index];
     669         156 : }
     670             : 
     671             : template <class BlockEdgesAdder>
     672        3160 : void IrreducibleGraph::addEdges(const BlockNode &Node,
     673             :                                 const BFIBase::LoopData *OuterLoop,
     674             :                                 BlockEdgesAdder addBlockEdges) {
     675        3160 :   auto L = Lookup.find(Node.Index);
     676        3160 :   if (L == Lookup.end())
     677         169 :     return;
     678        2991 :   IrrNode &Irr = *L->second;
     679        2991 :   const auto &Working = BFI.Working[Node.Index];
     680             : 
     681        2991 :   if (Working.isAPackage())
     682        3318 :     for (const auto &I : Working.Loop->Exits)
     683        1487 :       addEdge(Irr, I.first, OuterLoop);
     684             :   else
     685        2819 :     addBlockEdges(*this, Irr, OuterLoop);
     686             : }
     687             : 
     688             : } // end namespace bfi_detail
     689             : 
     690             : /// \brief Shared implementation for block frequency analysis.
     691             : ///
     692             : /// This is a shared implementation of BlockFrequencyInfo and
     693             : /// MachineBlockFrequencyInfo, and calculates the relative frequencies of
     694             : /// blocks.
     695             : ///
     696             : /// LoopInfo defines a loop as a "non-trivial" SCC dominated by a single block,
     697             : /// which is called the header.  A given loop, L, can have sub-loops, which are
     698             : /// loops within the subgraph of L that exclude its header.  (A "trivial" SCC
     699             : /// consists of a single block that does not have a self-edge.)
     700             : ///
     701             : /// In addition to loops, this algorithm has limited support for irreducible
     702             : /// SCCs, which are SCCs with multiple entry blocks.  Irreducible SCCs are
     703             : /// discovered on they fly, and modelled as loops with multiple headers.
     704             : ///
     705             : /// The headers of irreducible sub-SCCs consist of its entry blocks and all
     706             : /// nodes that are targets of a backedge within it (excluding backedges within
     707             : /// true sub-loops).  Block frequency calculations act as if a block is
     708             : /// inserted that intercepts all the edges to the headers.  All backedges and
     709             : /// entries point to this block.  Its successors are the headers, which split
     710             : /// the frequency evenly.
     711             : ///
     712             : /// This algorithm leverages BlockMass and ScaledNumber to maintain precision,
     713             : /// separates mass distribution from loop scaling, and dithers to eliminate
     714             : /// probability mass loss.
     715             : ///
     716             : /// The implementation is split between BlockFrequencyInfoImpl, which knows the
     717             : /// type of graph being modelled (BasicBlock vs. MachineBasicBlock), and
     718             : /// BlockFrequencyInfoImplBase, which doesn't.  The base class uses \a
     719             : /// BlockNode, a wrapper around a uint32_t.  BlockNode is numbered from 0 in
     720             : /// reverse-post order.  This gives two advantages:  it's easy to compare the
     721             : /// relative ordering of two nodes, and maps keyed on BlockT can be represented
     722             : /// by vectors.
     723             : ///
     724             : /// This algorithm is O(V+E), unless there is irreducible control flow, in
     725             : /// which case it's O(V*E) in the worst case.
     726             : ///
     727             : /// These are the main stages:
     728             : ///
     729             : ///  0. Reverse post-order traversal (\a initializeRPOT()).
     730             : ///
     731             : ///     Run a single post-order traversal and save it (in reverse) in RPOT.
     732             : ///     All other stages make use of this ordering.  Save a lookup from BlockT
     733             : ///     to BlockNode (the index into RPOT) in Nodes.
     734             : ///
     735             : ///  1. Loop initialization (\a initializeLoops()).
     736             : ///
     737             : ///     Translate LoopInfo/MachineLoopInfo into a form suitable for the rest of
     738             : ///     the algorithm.  In particular, store the immediate members of each loop
     739             : ///     in reverse post-order.
     740             : ///
     741             : ///  2. Calculate mass and scale in loops (\a computeMassInLoops()).
     742             : ///
     743             : ///     For each loop (bottom-up), distribute mass through the DAG resulting
     744             : ///     from ignoring backedges and treating sub-loops as a single pseudo-node.
     745             : ///     Track the backedge mass distributed to the loop header, and use it to
     746             : ///     calculate the loop scale (number of loop iterations).  Immediate
     747             : ///     members that represent sub-loops will already have been visited and
     748             : ///     packaged into a pseudo-node.
     749             : ///
     750             : ///     Distributing mass in a loop is a reverse-post-order traversal through
     751             : ///     the loop.  Start by assigning full mass to the Loop header.  For each
     752             : ///     node in the loop:
     753             : ///
     754             : ///         - Fetch and categorize the weight distribution for its successors.
     755             : ///           If this is a packaged-subloop, the weight distribution is stored
     756             : ///           in \a LoopData::Exits.  Otherwise, fetch it from
     757             : ///           BranchProbabilityInfo.
     758             : ///
     759             : ///         - Each successor is categorized as \a Weight::Local, a local edge
     760             : ///           within the current loop, \a Weight::Backedge, a backedge to the
     761             : ///           loop header, or \a Weight::Exit, any successor outside the loop.
     762             : ///           The weight, the successor, and its category are stored in \a
     763             : ///           Distribution.  There can be multiple edges to each successor.
     764             : ///
     765             : ///         - If there's a backedge to a non-header, there's an irreducible SCC.
     766             : ///           The usual flow is temporarily aborted.  \a
     767             : ///           computeIrreducibleMass() finds the irreducible SCCs within the
     768             : ///           loop, packages them up, and restarts the flow.
     769             : ///
     770             : ///         - Normalize the distribution:  scale weights down so that their sum
     771             : ///           is 32-bits, and coalesce multiple edges to the same node.
     772             : ///
     773             : ///         - Distribute the mass accordingly, dithering to minimize mass loss,
     774             : ///           as described in \a distributeMass().
     775             : ///
     776             : ///     In the case of irreducible loops, instead of a single loop header,
     777             : ///     there will be several. The computation of backedge masses is similar
     778             : ///     but instead of having a single backedge mass, there will be one
     779             : ///     backedge per loop header. In these cases, each backedge will carry
     780             : ///     a mass proportional to the edge weights along the corresponding
     781             : ///     path.
     782             : ///
     783             : ///     At the end of propagation, the full mass assigned to the loop will be
     784             : ///     distributed among the loop headers proportionally according to the
     785             : ///     mass flowing through their backedges.
     786             : ///
     787             : ///     Finally, calculate the loop scale from the accumulated backedge mass.
     788             : ///
     789             : ///  3. Distribute mass in the function (\a computeMassInFunction()).
     790             : ///
     791             : ///     Finally, distribute mass through the DAG resulting from packaging all
     792             : ///     loops in the function.  This uses the same algorithm as distributing
     793             : ///     mass in a loop, except that there are no exit or backedge edges.
     794             : ///
     795             : ///  4. Unpackage loops (\a unwrapLoops()).
     796             : ///
     797             : ///     Initialize each block's frequency to a floating point representation of
     798             : ///     its mass.
     799             : ///
     800             : ///     Visit loops top-down, scaling the frequencies of its immediate members
     801             : ///     by the loop's pseudo-node's frequency.
     802             : ///
     803             : ///  5. Convert frequencies to a 64-bit range (\a finalizeMetrics()).
     804             : ///
     805             : ///     Using the min and max frequencies as a guide, translate floating point
     806             : ///     frequencies to an appropriate range in uint64_t.
     807             : ///
     808             : /// It has some known flaws.
     809             : ///
     810             : ///   - The model of irreducible control flow is a rough approximation.
     811             : ///
     812             : ///     Modelling irreducible control flow exactly involves setting up and
     813             : ///     solving a group of infinite geometric series.  Such precision is
     814             : ///     unlikely to be worthwhile, since most of our algorithms give up on
     815             : ///     irreducible control flow anyway.
     816             : ///
     817             : ///     Nevertheless, we might find that we need to get closer.  Here's a sort
     818             : ///     of TODO list for the model with diminishing returns, to be completed as
     819             : ///     necessary.
     820             : ///
     821             : ///       - The headers for the \a LoopData representing an irreducible SCC
     822             : ///         include non-entry blocks.  When these extra blocks exist, they
     823             : ///         indicate a self-contained irreducible sub-SCC.  We could treat them
     824             : ///         as sub-loops, rather than arbitrarily shoving the problematic
     825             : ///         blocks into the headers of the main irreducible SCC.
     826             : ///
     827             : ///       - Entry frequencies are assumed to be evenly split between the
     828             : ///         headers of a given irreducible SCC, which is the only option if we
     829             : ///         need to compute mass in the SCC before its parent loop.  Instead,
     830             : ///         we could partially compute mass in the parent loop, and stop when
     831             : ///         we get to the SCC.  Here, we have the correct ratio of entry
     832             : ///         masses, which we can use to adjust their relative frequencies.
     833             : ///         Compute mass in the SCC, and then continue propagation in the
     834             : ///         parent.
     835             : ///
     836             : ///       - We can propagate mass iteratively through the SCC, for some fixed
     837             : ///         number of iterations.  Each iteration starts by assigning the entry
     838             : ///         blocks their backedge mass from the prior iteration.  The final
     839             : ///         mass for each block (and each exit, and the total backedge mass
     840             : ///         used for computing loop scale) is the sum of all iterations.
     841             : ///         (Running this until fixed point would "solve" the geometric
     842             : ///         series by simulation.)
     843     3179493 : template <class BT> class BlockFrequencyInfoImpl : BlockFrequencyInfoImplBase {
     844             :   // This is part of a workaround for a GCC 4.7 crash on lambdas.
     845             :   friend struct bfi_detail::BlockEdgesAdder<BT>;
     846             : 
     847             :   using BlockT = typename bfi_detail::TypeMap<BT>::BlockT;
     848             :   using FunctionT = typename bfi_detail::TypeMap<BT>::FunctionT;
     849             :   using BranchProbabilityInfoT =
     850             :       typename bfi_detail::TypeMap<BT>::BranchProbabilityInfoT;
     851             :   using LoopT = typename bfi_detail::TypeMap<BT>::LoopT;
     852             :   using LoopInfoT = typename bfi_detail::TypeMap<BT>::LoopInfoT;
     853             :   using Successor = GraphTraits<const BlockT *>;
     854             :   using Predecessor = GraphTraits<Inverse<const BlockT *>>;
     855             : 
     856             :   const BranchProbabilityInfoT *BPI = nullptr;
     857             :   const LoopInfoT *LI = nullptr;
     858             :   const FunctionT *F = nullptr;
     859             : 
     860             :   // All blocks in reverse postorder.
     861             :   std::vector<const BlockT *> RPOT;
     862             :   DenseMap<const BlockT *, BlockNode> Nodes;
     863             : 
     864             :   using rpot_iterator = typename std::vector<const BlockT *>::const_iterator;
     865             : 
     866     6061890 :   rpot_iterator rpot_begin() const { return RPOT.begin(); }
     867     1060041 :   rpot_iterator rpot_end() const { return RPOT.end(); }
     868             : 
     869             :   size_t getIndex(const rpot_iterator &I) const { return I - rpot_begin(); }
     870             : 
     871             :   BlockNode getNode(const rpot_iterator &I) const {
     872     5001849 :     return BlockNode(getIndex(I));
     873             :   }
     874     8873710 :   BlockNode getNode(const BlockT *BB) const { return Nodes.lookup(BB); }
     875             : 
     876             :   const BlockT *getBlock(const BlockNode &Node) const {
     877             :     assert(Node.Index < RPOT.size());
     878     5004340 :     return RPOT[Node.Index];
     879             :   }
     880             : 
     881             :   /// \brief Run (and save) a post-order traversal.
     882             :   ///
     883             :   /// Saves a reverse post-order traversal of all the nodes in \a F.
     884             :   void initializeRPOT();
     885             : 
     886             :   /// \brief Initialize loop data.
     887             :   ///
     888             :   /// Build up \a Loops using \a LoopInfo.  \a LoopInfo gives us a mapping from
     889             :   /// each block to the deepest loop it's in, but we need the inverse.  For each
     890             :   /// loop, we store in reverse post-order its "immediate" members, defined as
     891             :   /// the header, the headers of immediate sub-loops, and all other blocks in
     892             :   /// the loop that are not in sub-loops.
     893             :   void initializeLoops();
     894             : 
     895             :   /// \brief Propagate to a block's successors.
     896             :   ///
     897             :   /// In the context of distributing mass through \c OuterLoop, divide the mass
     898             :   /// currently assigned to \c Node between its successors.
     899             :   ///
     900             :   /// \return \c true unless there's an irreducible backedge.
     901             :   bool propagateMassToSuccessors(LoopData *OuterLoop, const BlockNode &Node);
     902             : 
     903             :   /// \brief Compute mass in a particular loop.
     904             :   ///
     905             :   /// Assign mass to \c Loop's header, and then for each block in \c Loop in
     906             :   /// reverse post-order, distribute mass to its successors.  Only visits nodes
     907             :   /// that have not been packaged into sub-loops.
     908             :   ///
     909             :   /// \pre \a computeMassInLoop() has been called for each subloop of \c Loop.
     910             :   /// \return \c true unless there's an irreducible backedge.
     911             :   bool computeMassInLoop(LoopData &Loop);
     912             : 
     913             :   /// \brief Try to compute mass in the top-level function.
     914             :   ///
     915             :   /// Assign mass to the entry block, and then for each block in reverse
     916             :   /// post-order, distribute mass to its successors.  Skips nodes that have
     917             :   /// been packaged into loops.
     918             :   ///
     919             :   /// \pre \a computeMassInLoops() has been called.
     920             :   /// \return \c true unless there's an irreducible backedge.
     921             :   bool tryToComputeMassInFunction();
     922             : 
     923             :   /// \brief Compute mass in (and package up) irreducible SCCs.
     924             :   ///
     925             :   /// Find the irreducible SCCs in \c OuterLoop, add them to \a Loops (in front
     926             :   /// of \c Insert), and call \a computeMassInLoop() on each of them.
     927             :   ///
     928             :   /// If \c OuterLoop is \c nullptr, it refers to the top-level function.
     929             :   ///
     930             :   /// \pre \a computeMassInLoop() has been called for each subloop of \c
     931             :   /// OuterLoop.
     932             :   /// \pre \c Insert points at the last loop successfully processed by \a
     933             :   /// computeMassInLoop().
     934             :   /// \pre \c OuterLoop has irreducible SCCs.
     935             :   void computeIrreducibleMass(LoopData *OuterLoop,
     936             :                               std::list<LoopData>::iterator Insert);
     937             : 
     938             :   /// \brief Compute mass in all loops.
     939             :   ///
     940             :   /// For each loop bottom-up, call \a computeMassInLoop().
     941             :   ///
     942             :   /// \a computeMassInLoop() aborts (and returns \c false) on loops that
     943             :   /// contain a irreducible sub-SCCs.  Use \a computeIrreducibleMass() and then
     944             :   /// re-enter \a computeMassInLoop().
     945             :   ///
     946             :   /// \post \a computeMassInLoop() has returned \c true for every loop.
     947             :   void computeMassInLoops();
     948             : 
     949             :   /// \brief Compute mass in the top-level function.
     950             :   ///
     951             :   /// Uses \a tryToComputeMassInFunction() and \a computeIrreducibleMass() to
     952             :   /// compute mass in the top-level function.
     953             :   ///
     954             :   /// \post \a tryToComputeMassInFunction() has returned \c true.
     955             :   void computeMassInFunction();
     956             : 
     957           0 :   std::string getBlockName(const BlockNode &Node) const override {
     958           0 :     return bfi_detail::getBlockName(getBlock(Node));
     959             :   }
     960             : 
     961             : public:
     962     4239721 :   BlockFrequencyInfoImpl() = default;
     963             : 
     964             :   const FunctionT *getFunction() const { return F; }
     965             : 
     966             :   void calculate(const FunctionT &F, const BranchProbabilityInfoT &BPI,
     967             :                  const LoopInfoT &LI);
     968             : 
     969             :   using BlockFrequencyInfoImplBase::getEntryFreq;
     970             : 
     971     6596368 :   BlockFrequency getBlockFreq(const BlockT *BB) const {
     972    13192736 :     return BlockFrequencyInfoImplBase::getBlockFreq(getNode(BB));
     973             :   }
     974             : 
     975         736 :   Optional<uint64_t> getBlockProfileCount(const Function &F,
     976             :                                           const BlockT *BB) const {
     977        1472 :     return BlockFrequencyInfoImplBase::getBlockProfileCount(F, getNode(BB));
     978             :   }
     979             : 
     980             :   Optional<uint64_t> getProfileCountFromFreq(const Function &F,
     981             :                                              uint64_t Freq) const {
     982          85 :     return BlockFrequencyInfoImplBase::getProfileCountFromFreq(F, Freq);
     983             :   }
     984             : 
     985         259 :   bool isIrrLoopHeader(const BlockT *BB) {
     986         518 :     return BlockFrequencyInfoImplBase::isIrrLoopHeader(getNode(BB));
     987             :   }
     988             : 
     989             :   void setBlockFreq(const BlockT *BB, uint64_t Freq);
     990             : 
     991         522 :   Scaled64 getFloatingBlockFreq(const BlockT *BB) const {
     992        1044 :     return BlockFrequencyInfoImplBase::getFloatingBlockFreq(getNode(BB));
     993             :   }
     994             : 
     995             :   const BranchProbabilityInfoT &getBPI() const { return *BPI; }
     996             : 
     997             :   /// \brief Print the frequencies for the current function.
     998             :   ///
     999             :   /// Prints the frequencies for the blocks in the current function.
    1000             :   ///
    1001             :   /// Blocks are printed in the natural iteration order of the function, rather
    1002             :   /// than reverse post-order.  This provides two advantages:  writing -analyze
    1003             :   /// tests is easier (since blocks come out in source order), and even
    1004             :   /// unreachable blocks are printed.
    1005             :   ///
    1006             :   /// \a BlockFrequencyInfoImplBase::print() only knows reverse post-order, so
    1007             :   /// we need to override it here.
    1008             :   raw_ostream &print(raw_ostream &OS) const override;
    1009             : 
    1010             :   using BlockFrequencyInfoImplBase::dump;
    1011             :   using BlockFrequencyInfoImplBase::printBlockFreq;
    1012             : 
    1013           0 :   raw_ostream &printBlockFreq(raw_ostream &OS, const BlockT *BB) const {
    1014           0 :     return BlockFrequencyInfoImplBase::printBlockFreq(OS, getNode(BB));
    1015             :   }
    1016             : };
    1017             : 
    1018             : template <class BT>
    1019     1059930 : void BlockFrequencyInfoImpl<BT>::calculate(const FunctionT &F,
    1020             :                                            const BranchProbabilityInfoT &BPI,
    1021             :                                            const LoopInfoT &LI) {
    1022             :   // Save the parameters.
    1023     1059930 :   this->BPI = &BPI;
    1024     1059930 :   this->LI = &LI;
    1025     1059930 :   this->F = &F;
    1026             : 
    1027             :   // Clean up left-over data structures.
    1028     1059930 :   BlockFrequencyInfoImplBase::clear();
    1029             :   RPOT.clear();
    1030     1059929 :   Nodes.clear();
    1031             : 
    1032             :   // Initialize.
    1033             :   DEBUG(dbgs() << "\nblock-frequency: " << F.getName() << "\n================="
    1034             :                << std::string(F.getName().size(), '=') << "\n");
    1035     1059931 :   initializeRPOT();
    1036     1059930 :   initializeLoops();
    1037             : 
    1038             :   // Visit loops in post-order to find the local mass distribution, and then do
    1039             :   // the full function.
    1040     1059931 :   computeMassInLoops();
    1041     1059931 :   computeMassInFunction();
    1042     1059931 :   unwrapLoops();
    1043     1059930 :   finalizeMetrics();
    1044     1059930 : }
    1045             : 
    1046             : template <class BT>
    1047        2012 : void BlockFrequencyInfoImpl<BT>::setBlockFreq(const BlockT *BB, uint64_t Freq) {
    1048        2012 :   if (Nodes.count(BB))
    1049        2364 :     BlockFrequencyInfoImplBase::setBlockFreq(getNode(BB), Freq);
    1050             :   else {
    1051             :     // If BB is a newly added block after BFI is done, we need to create a new
    1052             :     // BlockNode for it assigned with a new index. The index can be determined
    1053             :     // by the size of Freqs.
    1054        1660 :     BlockNode NewNode(Freqs.size());
    1055         830 :     Nodes[BB] = NewNode;
    1056         830 :     Freqs.emplace_back();
    1057         830 :     BlockFrequencyInfoImplBase::setBlockFreq(NewNode, Freq);
    1058             :   }
    1059        2012 : }
    1060             : 
    1061     1059931 : template <class BT> void BlockFrequencyInfoImpl<BT>::initializeRPOT() {
    1062     1059931 :   const BlockT *Entry = &F->front();
    1063     2119862 :   RPOT.reserve(F->size());
    1064     1059930 :   std::copy(po_begin(Entry), po_end(Entry), std::back_inserter(RPOT));
    1065             :   std::reverse(RPOT.begin(), RPOT.end());
    1066             : 
    1067             :   assert(RPOT.size() - 1 <= BlockNode::getMaxIndex() &&
    1068             :          "More nodes in function than Block Frequency Info supports");
    1069             : 
    1070             :   DEBUG(dbgs() << "reverse-post-order-traversal\n");
    1071     3560426 :   for (rpot_iterator I = rpot_begin(), E = rpot_end(); I != E; ++I) {
    1072             :     BlockNode Node = getNode(I);
    1073             :     DEBUG(dbgs() << " - " << getIndex(I) << ": " << getBlockName(Node) << "\n");
    1074     5000992 :     Nodes[*I] = Node;
    1075             :   }
    1076             : 
    1077     2119860 :   Working.reserve(RPOT.size());
    1078     7120850 :   for (size_t Index = 0; Index < RPOT.size(); ++Index)
    1079     2500495 :     Working.emplace_back(Index);
    1080     1059930 :   Freqs.resize(RPOT.size());
    1081     1059930 : }
    1082             : 
    1083     1059931 : template <class BT> void BlockFrequencyInfoImpl<BT>::initializeLoops() {
    1084             :   DEBUG(dbgs() << "loop-detection\n");
    1085     2119862 :   if (LI->empty())
    1086     1021825 :     return;
    1087             : 
    1088             :   // Visit loops top down and assign them an index.
    1089             :   std::deque<std::pair<const LoopT *, LoopData *>> Q;
    1090      125384 :   for (const LoopT *L : *LI)
    1091       49172 :     Q.emplace_back(L, nullptr);
    1092      152138 :   while (!Q.empty()) {
    1093       57016 :     const LoopT *Loop = Q.front().first;
    1094       57016 :     LoopData *Parent = Q.front().second;
    1095       57016 :     Q.pop_front();
    1096             : 
    1097       57016 :     BlockNode Header = getNode(Loop->getHeader());
    1098             :     assert(Header.isValid());
    1099             : 
    1100       57016 :     Loops.emplace_back(Parent, Header);
    1101      114032 :     Working[Header.Index].Loop = &Loops.back();
    1102             :     DEBUG(dbgs() << " - loop = " << getBlockName(Header) << "\n");
    1103             : 
    1104       64860 :     for (const LoopT *L : *Loop)
    1105        7844 :       Q.emplace_back(L, &Loops.back());
    1106             :   }
    1107             : 
    1108             :   // Visit nodes in reverse post-order and add them to their deepest containing
    1109             :   // loop.
    1110     2589294 :   for (size_t Index = 0; Index < RPOT.size(); ++Index) {
    1111             :     // Loop headers have already been mostly mapped.
    1112      837694 :     if (Working[Index].isLoopHeader()) {
    1113       57016 :       LoopData *ContainingLoop = Working[Index].getContainingLoop();
    1114       57016 :       if (ContainingLoop)
    1115       15688 :         ContainingLoop->Nodes.push_back(Index);
    1116       57016 :       continue;
    1117             :     }
    1118             : 
    1119     1561356 :     const LoopT *Loop = LI->getLoopFor(RPOT[Index]);
    1120      201520 :     if (!Loop)
    1121      579158 :       continue;
    1122             : 
    1123             :     // Add this node to its containing loop's member list.
    1124             :     BlockNode Header = getNode(Loop->getHeader());
    1125             :     assert(Header.isValid());
    1126      201520 :     const auto &HeaderData = Working[Header.Index];
    1127             :     assert(HeaderData.isLoopHeader());
    1128             : 
    1129      201520 :     Working[Index].Loop = HeaderData.Loop;
    1130      403040 :     HeaderData.Loop->Nodes.push_back(Index);
    1131             :     DEBUG(dbgs() << " - loop = " << getBlockName(Header)
    1132             :                  << ": member = " << getBlockName(Index) << "\n");
    1133             :   }
    1134             : }
    1135             : 
    1136     1059931 : template <class BT> void BlockFrequencyInfoImpl<BT>::computeMassInLoops() {
    1137             :   // Visit loops with the deepest first, and the top-level loops last.
    1138     1116947 :   for (auto L = Loops.rbegin(), E = Loops.rend(); L != E; ++L) {
    1139       57016 :     if (computeMassInLoop(*L))
    1140       56971 :       continue;
    1141             :     auto Next = std::next(L);
    1142          45 :     computeIrreducibleMass(&*L, L.base());
    1143             :     L = std::prev(Next);
    1144          45 :     if (computeMassInLoop(*L))
    1145          45 :       continue;
    1146           0 :     llvm_unreachable("unhandled irreducible control flow");
    1147             :   }
    1148     1059931 : }
    1149             : 
    1150             : template <class BT>
    1151       57220 : bool BlockFrequencyInfoImpl<BT>::computeMassInLoop(LoopData &Loop) {
    1152             :   // Compute mass in loop.
    1153             :   DEBUG(dbgs() << "compute-mass-in-loop: " << getLoopName(Loop) << "\n");
    1154             : 
    1155       57220 :   if (Loop.isIrreducible()) {
    1156             :     DEBUG(dbgs() << "isIrreducible = true\n");
    1157             :     Distribution Dist;
    1158             :     unsigned NumHeadersWithWeight = 0;
    1159             :     Optional<uint64_t> MinHeaderWeight;
    1160             :     DenseSet<uint32_t> HeadersWithoutWeight;
    1161         159 :     HeadersWithoutWeight.reserve(Loop.NumHeaders);
    1162         727 :     for (uint32_t H = 0; H < Loop.NumHeaders; ++H) {
    1163         568 :       auto &HeaderNode = Loop.Nodes[H];
    1164             :       const BlockT *Block = getBlock(HeaderNode);
    1165         568 :       IsIrrLoopHeader.set(Loop.Nodes[H].Index);
    1166         253 :       Optional<uint64_t> HeaderWeight = Block->getIrrLoopHeaderWeight();
    1167        1120 :       if (!HeaderWeight) {
    1168             :         DEBUG(dbgs() << "Missing irr loop header metadata on "
    1169             :               << getBlockName(HeaderNode) << "\n");
    1170             :         HeadersWithoutWeight.insert(H);
    1171             :         continue;
    1172             :       }
    1173             :       DEBUG(dbgs() << getBlockName(HeaderNode)
    1174             :             << " has irr loop header weight " << HeaderWeight.getValue()
    1175             :             << "\n");
    1176          16 :       NumHeadersWithWeight++;
    1177          16 :       uint64_t HeaderWeightValue = HeaderWeight.getValue();
    1178          16 :       if (!MinHeaderWeight || HeaderWeightValue < MinHeaderWeight)
    1179             :         MinHeaderWeight = HeaderWeightValue;
    1180          16 :       if (HeaderWeightValue) {
    1181             :         Dist.addLocal(HeaderNode, HeaderWeightValue);
    1182             :       }
    1183             :     }
    1184             :     // As a heuristic, if some headers don't have a weight, give them the
    1185             :     // minimium weight seen (not to disrupt the existing trends too much by
    1186             :     // using a weight that's in the general range of the other headers' weights,
    1187             :     // and the minimum seems to perform better than the average.)
    1188             :     // FIXME: better update in the passes that drop the header weight.
    1189             :     // If no headers have a weight, give them even weight (use weight 1).
    1190         159 :     if (!MinHeaderWeight)
    1191             :       MinHeaderWeight = 1;
    1192         711 :     for (uint32_t H : HeadersWithoutWeight) {
    1193         552 :       auto &HeaderNode = Loop.Nodes[H];
    1194             :       assert(!getBlock(HeaderNode)->getIrrLoopHeaderWeight() &&
    1195             :              "Shouldn't have a weight metadata");
    1196             :       uint64_t MinWeight = MinHeaderWeight.getValue();
    1197             :       DEBUG(dbgs() << "Giving weight " << MinWeight
    1198             :             << " to " << getBlockName(HeaderNode) << "\n");
    1199         552 :       if (MinWeight)
    1200             :         Dist.addLocal(HeaderNode, MinWeight);
    1201             :     }
    1202         159 :     distributeIrrLoopHeaderMass(Dist);
    1203        3937 :     for (const BlockNode &M : Loop.Nodes)
    1204        1889 :       if (!propagateMassToSuccessors(&Loop, M))
    1205           0 :         llvm_unreachable("unhandled irreducible control flow");
    1206         159 :     if (NumHeadersWithWeight == 0)
    1207             :       // No headers have a metadata. Adjust header mass.
    1208         153 :       adjustLoopHeaderMass(Loop);
    1209             :   } else {
    1210      114122 :     Working[Loop.getHeader().Index].getMass() = BlockMass::getFull();
    1211       57061 :     if (!propagateMassToSuccessors(&Loop, Loop.getHeader()))
    1212           0 :       llvm_unreachable("irreducible control flow to loop header!?");
    1213      475845 :     for (const BlockNode &M : Loop.members())
    1214      209437 :       if (!propagateMassToSuccessors(&Loop, M))
    1215             :         // Irreducible backedge.
    1216             :         return false;
    1217             :   }
    1218             : 
    1219       57175 :   computeLoopScale(Loop);
    1220       57175 :   packageLoop(Loop);
    1221       57175 :   return true;
    1222             : }
    1223             : 
    1224             : template <class BT>
    1225     1060042 : bool BlockFrequencyInfoImpl<BT>::tryToComputeMassInFunction() {
    1226             :   // Compute mass in function.
    1227             :   DEBUG(dbgs() << "compute-mass-in-function\n");
    1228             :   assert(!Working.empty() && "no blocks in function");
    1229             :   assert(!Working[0].isLoopHeader() && "entry block is a loop header");
    1230             : 
    1231     1060042 :   Working[0].getMass() = BlockMass::getFull();
    1232     3561284 :   for (rpot_iterator I = rpot_begin(), IE = rpot_end(); I != IE; ++I) {
    1233             :     // Check for nodes that have been packaged.
    1234     2501353 :     BlockNode Node = getNode(I);
    1235     5002706 :     if (Working[Node.Index].isPackaged())
    1236      210877 :       continue;
    1237             : 
    1238     2290476 :     if (!propagateMassToSuccessors(nullptr, Node))
    1239         111 :       return false;
    1240             :   }
    1241             :   return true;
    1242             : }
    1243             : 
    1244     1059931 : template <class BT> void BlockFrequencyInfoImpl<BT>::computeMassInFunction() {
    1245     1059931 :   if (tryToComputeMassInFunction())
    1246             :     return;
    1247         111 :   computeIrreducibleMass(nullptr, Loops.begin());
    1248         111 :   if (tryToComputeMassInFunction())
    1249             :     return;
    1250           0 :   llvm_unreachable("unhandled irreducible control flow");
    1251             : }
    1252             : 
    1253             : /// \note This should be a lambda, but that crashes GCC 4.7.
    1254             : namespace bfi_detail {
    1255             : 
    1256             : template <class BT> struct BlockEdgesAdder {
    1257             :   using BlockT = BT;
    1258             :   using LoopData = BlockFrequencyInfoImplBase::LoopData;
    1259             :   using Successor = GraphTraits<const BlockT *>;
    1260             : 
    1261             :   const BlockFrequencyInfoImpl<BT> &BFI;
    1262             : 
    1263         156 :   explicit BlockEdgesAdder(const BlockFrequencyInfoImpl<BT> &BFI)
    1264         156 :       : BFI(BFI) {}
    1265             : 
    1266        2819 :   void operator()(IrreducibleGraph &G, IrreducibleGraph::IrrNode &Irr,
    1267             :                   const LoopData *OuterLoop) {
    1268        5638 :     const BlockT *BB = BFI.RPOT[Irr.Node.Index];
    1269        5077 :     for (const auto Succ : children<const BlockT *>(BB))
    1270        8446 :       G.addEdge(Irr, BFI.getNode(Succ), OuterLoop);
    1271        2819 :   }
    1272             : };
    1273             : 
    1274             : } // end namespace bfi_detail
    1275             : 
    1276             : template <class BT>
    1277         156 : void BlockFrequencyInfoImpl<BT>::computeIrreducibleMass(
    1278             :     LoopData *OuterLoop, std::list<LoopData>::iterator Insert) {
    1279             :   DEBUG(dbgs() << "analyze-irreducible-in-";
    1280             :         if (OuterLoop) dbgs() << "loop: " << getLoopName(*OuterLoop) << "\n";
    1281             :         else dbgs() << "function\n");
    1282             : 
    1283             :   using namespace bfi_detail;
    1284             : 
    1285             :   // Ideally, addBlockEdges() would be declared here as a lambda, but that
    1286             :   // crashes GCC 4.7.
    1287             :   BlockEdgesAdder<BT> addBlockEdges(*this);
    1288         201 :   IrreducibleGraph G(*this, OuterLoop, addBlockEdges);
    1289             : 
    1290         156 :   for (auto &L : analyzeIrreducible(G, OuterLoop, Insert))
    1291         159 :     computeMassInLoop(L);
    1292             : 
    1293         156 :   if (!OuterLoop)
    1294         111 :     return;
    1295          45 :   updateLoopWithIrreducible(*OuterLoop);
    1296             : }
    1297             : 
    1298             : // A helper function that converts a branch probability into weight.
    1299             : inline uint32_t getWeightFromBranchProb(const BranchProbability Prob) {
    1300             :   return Prob.getNumerator();
    1301             : }
    1302             : 
    1303             : template <class BT>
    1304             : bool
    1305     2558862 : BlockFrequencyInfoImpl<BT>::propagateMassToSuccessors(LoopData *OuterLoop,
    1306             :                                                       const BlockNode &Node) {
    1307             :   DEBUG(dbgs() << " - node: " << getBlockName(Node) << "\n");
    1308             :   // Calculate probability for successors.
    1309             :   Distribution Dist;
    1310     5117724 :   if (auto *Loop = Working[Node.Index].getPackagedLoop()) {
    1311             :     assert(Loop != OuterLoop && "Cannot propagate mass in a packaged loop");
    1312       57260 :     if (!addLoopSuccessorsToDist(OuterLoop, *Loop, Dist))
    1313             :       // Irreducible backedge.
    1314             :       return false;
    1315             :   } else {
    1316             :     const BlockT *BB = getBlock(Node);
    1317     1213556 :     for (auto SI = GraphTraits<const BlockT *>::child_begin(BB),
    1318             :               SE = GraphTraits<const BlockT *>::child_end(BB);
    1319     4514008 :          SI != SE; ++SI)
    1320     8050176 :       if (!addToDist(
    1321     4893021 :               Dist, OuterLoop, Node, getNode(*SI),
    1322     2012544 :               getWeightFromBranchProb(BPI->getEdgeProbability(BB, SI))))
    1323             :         // Irreducible backedge.
    1324          76 :         return false;
    1325             :   }
    1326             : 
    1327             :   // Distribute mass to successors, saving exit and backedge data in the
    1328             :   // loop header.
    1329     2558704 :   distributeMass(Node, OuterLoop, Dist);
    1330     2558705 :   return true;
    1331             : }
    1332             : 
    1333             : template <class BT>
    1334          61 : raw_ostream &BlockFrequencyInfoImpl<BT>::print(raw_ostream &OS) const {
    1335          61 :   if (!F)
    1336             :     return OS;
    1337          61 :   OS << "block-frequency-info: " << F->getName() << "\n";
    1338         644 :   for (const BlockT &BB : *F) {
    1339        1566 :     OS << " - " << bfi_detail::getBlockName(&BB) << ": float = ";
    1340        1566 :     getFloatingBlockFreq(&BB).print(OS, 5)
    1341        1566 :         << ", int = " << getBlockFreq(&BB).getFrequency();
    1342        1566 :     if (Optional<uint64_t> ProfileCount =
    1343             :         BlockFrequencyInfoImplBase::getBlockProfileCount(
    1344        1044 :             F->getFunction(), getNode(&BB)))
    1345          78 :       OS << ", count = " << ProfileCount.getValue();
    1346         522 :     if (Optional<uint64_t> IrrLoopHeaderWeight =
    1347             :         BB.getIrrLoopHeaderWeight())
    1348          16 :       OS << ", irr_loop_header_weight = " << IrrLoopHeaderWeight.getValue();
    1349         522 :     OS << "\n";
    1350             :   }
    1351             : 
    1352             :   // Add an extra newline for readability.
    1353          61 :   OS << "\n";
    1354          61 :   return OS;
    1355             : }
    1356             : 
    1357             : // Graph trait base class for block frequency information graph
    1358             : // viewer.
    1359             : 
    1360             : enum GVDAGType { GVDT_None, GVDT_Fraction, GVDT_Integer, GVDT_Count };
    1361             : 
    1362             : template <class BlockFrequencyInfoT, class BranchProbabilityInfoT>
    1363             : struct BFIDOTGraphTraitsBase : public DefaultDOTGraphTraits {
    1364             :   using GTraits = GraphTraits<BlockFrequencyInfoT *>;
    1365             :   using NodeRef = typename GTraits::NodeRef;
    1366             :   using EdgeIter = typename GTraits::ChildIteratorType;
    1367             :   using NodeIter = typename GTraits::nodes_iterator;
    1368             : 
    1369             :   uint64_t MaxFrequency = 0;
    1370             : 
    1371           0 :   explicit BFIDOTGraphTraitsBase(bool isSimple = false)
    1372           0 :       : DefaultDOTGraphTraits(isSimple) {}
    1373             : 
    1374           0 :   static std::string getGraphName(const BlockFrequencyInfoT *G) {
    1375           0 :     return G->getFunction()->getName();
    1376             :   }
    1377             : 
    1378           0 :   std::string getNodeAttributes(NodeRef Node, const BlockFrequencyInfoT *Graph,
    1379             :                                 unsigned HotPercentThreshold = 0) {
    1380             :     std::string Result;
    1381           0 :     if (!HotPercentThreshold)
    1382             :       return Result;
    1383             : 
    1384             :     // Compute MaxFrequency on the fly:
    1385           0 :     if (!MaxFrequency) {
    1386             :       for (NodeIter I = GTraits::nodes_begin(Graph),
    1387             :                     E = GTraits::nodes_end(Graph);
    1388           0 :            I != E; ++I) {
    1389             :         NodeRef N = *I;
    1390           0 :         MaxFrequency =
    1391           0 :             std::max(MaxFrequency, Graph->getBlockFreq(N).getFrequency());
    1392             :       }
    1393             :     }
    1394           0 :     BlockFrequency Freq = Graph->getBlockFreq(Node);
    1395           0 :     BlockFrequency HotFreq =
    1396           0 :         (BlockFrequency(MaxFrequency) *
    1397             :          BranchProbability::getBranchProbability(HotPercentThreshold, 100));
    1398             : 
    1399           0 :     if (Freq < HotFreq)
    1400             :       return Result;
    1401             : 
    1402           0 :     raw_string_ostream OS(Result);
    1403           0 :     OS << "color=\"red\"";
    1404             :     OS.flush();
    1405             :     return Result;
    1406             :   }
    1407             : 
    1408           0 :   std::string getNodeLabel(NodeRef Node, const BlockFrequencyInfoT *Graph,
    1409             :                            GVDAGType GType, int layout_order = -1) {
    1410             :     std::string Result;
    1411           0 :     raw_string_ostream OS(Result);
    1412             : 
    1413           0 :     if (layout_order != -1)
    1414           0 :       OS << Node->getName() << "[" << layout_order << "] : ";
    1415             :     else
    1416           0 :       OS << Node->getName() << " : ";
    1417           0 :     switch (GType) {
    1418           0 :     case GVDT_Fraction:
    1419           0 :       Graph->printBlockFreq(OS, Node);
    1420           0 :       break;
    1421           0 :     case GVDT_Integer:
    1422           0 :       OS << Graph->getBlockFreq(Node).getFrequency();
    1423           0 :       break;
    1424           0 :     case GVDT_Count: {
    1425           0 :       auto Count = Graph->getBlockProfileCount(Node);
    1426           0 :       if (Count)
    1427           0 :         OS << Count.getValue();
    1428             :       else
    1429           0 :         OS << "Unknown";
    1430             :       break;
    1431             :     }
    1432           0 :     case GVDT_None:
    1433           0 :       llvm_unreachable("If we are not supposed to render a graph we should "
    1434             :                        "never reach this point.");
    1435             :     }
    1436           0 :     return Result;
    1437             :   }
    1438             : 
    1439           0 :   std::string getEdgeAttributes(NodeRef Node, EdgeIter EI,
    1440             :                                 const BlockFrequencyInfoT *BFI,
    1441             :                                 const BranchProbabilityInfoT *BPI,
    1442             :                                 unsigned HotPercentThreshold = 0) {
    1443             :     std::string Str;
    1444           0 :     if (!BPI)
    1445             :       return Str;
    1446             : 
    1447           0 :     BranchProbability BP = BPI->getEdgeProbability(Node, EI);
    1448             :     uint32_t N = BP.getNumerator();
    1449             :     uint32_t D = BP.getDenominator();
    1450           0 :     double Percent = 100.0 * N / D;
    1451           0 :     raw_string_ostream OS(Str);
    1452           0 :     OS << format("label=\"%.1f%%\"", Percent);
    1453             : 
    1454           0 :     if (HotPercentThreshold) {
    1455           0 :       BlockFrequency EFreq = BFI->getBlockFreq(Node) * BP;
    1456           0 :       BlockFrequency HotFreq = BlockFrequency(MaxFrequency) *
    1457             :                                BranchProbability(HotPercentThreshold, 100);
    1458             : 
    1459           0 :       if (EFreq >= HotFreq) {
    1460           0 :         OS << ",color=\"red\"";
    1461             :       }
    1462             :     }
    1463             : 
    1464             :     OS.flush();
    1465             :     return Str;
    1466             :   }
    1467             : };
    1468             : 
    1469             : } // end namespace llvm
    1470             : 
    1471             : #undef DEBUG_TYPE
    1472             : 
    1473             : #endif // LLVM_ANALYSIS_BLOCKFREQUENCYINFOIMPL_H

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