From: Cong Hou Date: Wed, 4 Nov 2015 21:37:58 +0000 (+0000) Subject: Add new interfaces to MBB for manipulating successors with probabilities instead... X-Git-Url: http://plrg.eecs.uci.edu/git/?p=oota-llvm.git;a=commitdiff_plain;h=178bfbdf6096d23fac5fa751cede0a8310b37caf Add new interfaces to MBB for manipulating successors with probabilities instead of weights. NFC. This is part-1 of the patch that replaces all edge weights in MBB by probabilities, which only adds new interfaces. No functional changes. Differential revision: http://reviews.llvm.org/D13908 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@252083 91177308-0d34-0410-b5e6-96231b3b80d8 --- diff --git a/include/llvm/CodeGen/MachineBasicBlock.h b/include/llvm/CodeGen/MachineBasicBlock.h index edf44884ec5..024c7a51ca7 100644 --- a/include/llvm/CodeGen/MachineBasicBlock.h +++ b/include/llvm/CodeGen/MachineBasicBlock.h @@ -16,6 +16,7 @@ #include "llvm/ADT/GraphTraits.h" #include "llvm/CodeGen/MachineInstr.h" +#include "llvm/Support/BranchProbability.h" #include "llvm/MC/MCRegisterInfo.h" #include "llvm/Support/DataTypes.h" #include @@ -96,6 +97,14 @@ private: typedef std::vector::iterator weight_iterator; typedef std::vector::const_iterator const_weight_iterator; + /// Keep track of the probabilities to the successors. This vector has the + /// same order as Successors, or it is empty if we don't use it (disable + /// optimization). + std::vector Probs; + typedef std::vector::iterator probability_iterator; + typedef std::vector::const_iterator + const_probability_iterator; + /// Keep track of the physical registers that are livein of the basicblock. typedef std::vector LiveInVector; LiveInVector LiveIns; @@ -431,9 +440,31 @@ public: /// used. Using this interface can save some space. void addSuccessorWithoutWeight(MachineBasicBlock *Succ); + /// Add Succ as a successor of this MachineBasicBlock. The Predecessors list + /// of Succ is automatically updated. PROB parameter is stored in + /// Probabilities list. + /// + /// Note that duplicate Machine CFG edges are not allowed. + void addSuccessor(MachineBasicBlock *Succ, BranchProbability Prob); + + /// Add Succ as a successor of this MachineBasicBlock. The Predecessors list + /// of Succ is automatically updated. The probability is not provided because + /// BPI is not available (e.g. -O0 is used), in which case edge probabilities + /// won't be used. Using this interface can save some space. + void addSuccessorWithoutProb(MachineBasicBlock *Succ); + /// Set successor weight of a given iterator. void setSuccWeight(succ_iterator I, uint32_t Weight); + /// Set successor probability of a given iterator. + void setSuccProbability(succ_iterator I, BranchProbability Prob); + + /// Normalize probabilities of all successors so that the sum of them becomes + /// one. + void normalizeSuccProbs() { + BranchProbability::normalizeProbabilities(Probs); + } + /// Remove successor from the successors list of this MachineBasicBlock. The /// Predecessors list of Succ is automatically updated. void removeSuccessor(MachineBasicBlock *Succ); @@ -458,6 +489,9 @@ public: /// Return true if any of the successors have weights attached to them. bool hasSuccessorWeights() const { return !Weights.empty(); } + /// Return true if any of the successors have probabilities attached to them. + bool hasSuccessorProbabilities() const { return !Probs.empty(); } + /// Return true if the specified MBB is a predecessor of this block. bool isPredecessor(const MachineBasicBlock *MBB) const; @@ -715,6 +749,11 @@ private: weight_iterator getWeightIterator(succ_iterator I); const_weight_iterator getWeightIterator(const_succ_iterator I) const; + /// Return probability iterator corresponding to the I successor iterator. + probability_iterator getProbabilityIterator(succ_iterator I); + const_probability_iterator + getProbabilityIterator(const_succ_iterator I) const; + friend class MachineBranchProbabilityInfo; friend class MIPrinter; @@ -723,6 +762,10 @@ private: /// MachineBranchProbabilityInfo class. uint32_t getSuccWeight(const_succ_iterator Succ) const; + /// Return probability of the edge from this block to MBB. This method should + /// NOT be called directly, but by using getEdgeProbability method from + /// MachineBranchProbabilityInfo class. + BranchProbability getSuccProbability(const_succ_iterator Succ) const; // Methods used to maintain doubly linked list of blocks... friend struct ilist_traits; diff --git a/include/llvm/Support/BranchProbability.h b/include/llvm/Support/BranchProbability.h index f204777066e..e3acb566b73 100644 --- a/include/llvm/Support/BranchProbability.h +++ b/include/llvm/Support/BranchProbability.h @@ -34,6 +34,7 @@ class BranchProbability { // Denominator, which is a constant value. static const uint32_t D = 1u << 31; + static const uint32_t UnknownN = UINT32_MAX; // Construct a BranchProbability with only numerator assuming the denominator // is 1<<31. For internal use only. @@ -44,9 +45,11 @@ public: BranchProbability(uint32_t Numerator, uint32_t Denominator); bool isZero() const { return N == 0; } + bool isUnknown() const { return N == UnknownN; } static BranchProbability getZero() { return BranchProbability(0); } static BranchProbability getOne() { return BranchProbability(D); } + static BranchProbability getUnknown() { return BranchProbability(UnknownN); } // Create a BranchProbability object with the given numerator and 1<<31 // as denominator. static BranchProbability getRaw(uint32_t N) { return BranchProbability(N); } @@ -133,6 +136,10 @@ inline raw_ostream &operator<<(raw_ostream &OS, BranchProbability Prob) { return Prob.print(OS); } +inline BranchProbability operator/(BranchProbability LHS, uint32_t RHS) { + return BranchProbability::getRaw(LHS.getNumerator() / RHS); +} + template void BranchProbability::normalizeProbabilities(ProbabilityList &Probs) { uint64_t Sum = 0; diff --git a/lib/CodeGen/MachineBasicBlock.cpp b/lib/CodeGen/MachineBasicBlock.cpp index ab865ff8152..1fdaf329075 100644 --- a/lib/CodeGen/MachineBasicBlock.cpp +++ b/lib/CodeGen/MachineBasicBlock.cpp @@ -523,6 +523,25 @@ void MachineBasicBlock::addSuccessorWithoutWeight(MachineBasicBlock *Succ) { Succ->addPredecessor(this); } +void MachineBasicBlock::addSuccessor(MachineBasicBlock *Succ, + BranchProbability Prob) { + // Probability list is either empty (if successor list isn't empty, this means + // disabled optimization) or has the same size as successor list. + if (!(Probs.empty() && !Successors.empty())) + Probs.push_back(Prob); + Successors.push_back(Succ); + Succ->addPredecessor(this); +} + +void MachineBasicBlock::addSuccessorWithoutProb(MachineBasicBlock *Succ) { + // We need to make sure probability list is either empty or has the same size + // of successor list. When this function is called, we can safely delete all + // probability in the list. + Probs.clear(); + Successors.push_back(Succ); + Succ->addPredecessor(this); +} + void MachineBasicBlock::removeSuccessor(MachineBasicBlock *Succ) { Succ->removePredecessor(this); succ_iterator I = std::find(Successors.begin(), Successors.end(), Succ); @@ -534,6 +553,13 @@ void MachineBasicBlock::removeSuccessor(MachineBasicBlock *Succ) { Weights.erase(WI); } + // If probability list is empty it means we don't use it (disabled + // optimization). + if (!Probs.empty()) { + probability_iterator WI = getProbabilityIterator(I); + Probs.erase(WI); + } + Successors.erase(I); } @@ -547,6 +573,13 @@ MachineBasicBlock::removeSuccessor(succ_iterator I) { Weights.erase(WI); } + // If probability list is empty it means we don't use it (disabled + // optimization). + if (!Probs.empty()) { + probability_iterator WI = getProbabilityIterator(I); + Probs.erase(WI); + } + (*I)->removePredecessor(this); return Successors.erase(I); } @@ -588,6 +621,12 @@ void MachineBasicBlock::replaceSuccessor(MachineBasicBlock *Old, *getWeightIterator(NewI) += *OldWI; Weights.erase(OldWI); } + // Update its probability instead of adding a duplicate edge. + if (!Probs.empty()) { + probability_iterator OldPI = getProbabilityIterator(OldI); + *getProbabilityIterator(NewI) += *OldPI; + Probs.erase(OldPI); + } Successors.erase(OldI); } @@ -1120,6 +1159,21 @@ uint32_t MachineBasicBlock::getSuccWeight(const_succ_iterator Succ) const { return *getWeightIterator(Succ); } +/// Return probability of the edge from this block to MBB. If probability list +/// is empty, return a default probability which is 1/N, where N is the number +/// of successors. If the probability of the given successor is unknown, then +/// sum up all known probabilities and return the complement of the sum divided +/// by the number of unknown probabilities. +BranchProbability +MachineBasicBlock::getSuccProbability(const_succ_iterator Succ) const { + if (Probs.empty()) + return BranchProbability(1, succ_size()); + + auto Prob = *getProbabilityIterator(Succ); + assert(!Prob.isUnknown()); + return Prob; +} + /// Set successor weight of a given iterator. void MachineBasicBlock::setSuccWeight(succ_iterator I, uint32_t Weight) { if (Weights.empty()) @@ -1127,6 +1181,15 @@ void MachineBasicBlock::setSuccWeight(succ_iterator I, uint32_t Weight) { *getWeightIterator(I) = Weight; } +/// Set successor probability of a given iterator. +void MachineBasicBlock::setSuccProbability(succ_iterator I, + BranchProbability Prob) { + assert(!Prob.isUnknown()); + if (Probs.empty()) + return; + *getProbabilityIterator(I) = Prob; +} + /// Return wight iterator corresonding to the I successor iterator. MachineBasicBlock::weight_iterator MachineBasicBlock:: getWeightIterator(MachineBasicBlock::succ_iterator I) { @@ -1145,6 +1208,25 @@ getWeightIterator(MachineBasicBlock::const_succ_iterator I) const { return Weights.begin() + index; } +/// Return probability iterator corresonding to the I successor iterator. +MachineBasicBlock::probability_iterator +MachineBasicBlock::getProbabilityIterator(MachineBasicBlock::succ_iterator I) { + assert(Probs.size() == Successors.size() && "Async probability list!"); + const size_t index = std::distance(Successors.begin(), I); + assert(index < Probs.size() && "Not a current successor!"); + return Probs.begin() + index; +} + +/// Return probability iterator corresonding to the I successor iterator +MachineBasicBlock::const_probability_iterator +MachineBasicBlock::getProbabilityIterator( + MachineBasicBlock::const_succ_iterator I) const { + assert(Probs.size() == Successors.size() && "Async probability list!"); + const size_t index = std::distance(Successors.begin(), I); + assert(index < Probs.size() && "Not a current successor!"); + return Probs.begin() + index; +} + /// Return whether (physical) register "Reg" has been ined and not ed /// as of just before "MI". ///