diff --git a/include/llvm/Analysis/BlockFrequencyInfoImpl.h b/include/llvm/Analysis/BlockFrequencyInfoImpl.h index 5e9920660c8..e5e9b479523 100644 --- a/include/llvm/Analysis/BlockFrequencyInfoImpl.h +++ b/include/llvm/Analysis/BlockFrequencyInfoImpl.h @@ -8,7 +8,6 @@ //===----------------------------------------------------------------------===// // // Shared implementation of BlockFrequency for IR and Machine Instructions. -// See the documentation below for BlockFrequencyInfoImpl for details. // //===----------------------------------------------------------------------===// @@ -17,7 +16,6 @@ #include "llvm/ADT/DenseMap.h" #include "llvm/ADT/PostOrderIterator.h" -#include "llvm/ADT/SCCIterator.h" #include "llvm/ADT/iterator_range.h" #include "llvm/IR/BasicBlock.h" #include "llvm/Support/BlockFrequency.h" @@ -898,10 +896,6 @@ class MachineFunction; class MachineLoop; class MachineLoopInfo; -namespace bfi_detail { -struct IrreducibleGraph; -} - /// \brief Base class for BlockFrequencyInfoImpl /// /// BlockFrequencyInfoImplBase has supporting data structures and some @@ -954,7 +948,6 @@ public: typedef SmallVector NodeList; LoopData *Parent; ///< The parent loop. bool IsPackaged; ///< Whether this has been packaged. - uint32_t NumHeaders; ///< Number of headers. ExitMap Exits; ///< Successor edges (and weights). NodeList Nodes; ///< Header and the members of the loop. BlockMass BackedgeMass; ///< Mass returned to loop header. @@ -962,26 +955,11 @@ public: Float Scale; LoopData(LoopData *Parent, const BlockNode &Header) - : Parent(Parent), IsPackaged(false), NumHeaders(1), Nodes(1, Header) {} - template - LoopData(LoopData *Parent, It1 FirstHeader, It1 LastHeader, It2 FirstOther, - It2 LastOther) - : Parent(Parent), IsPackaged(false), Nodes(FirstHeader, LastHeader) { - NumHeaders = Nodes.size(); - Nodes.insert(Nodes.end(), FirstOther, LastOther); - } - bool isHeader(const BlockNode &Node) const { - if (isIrreducible()) - return std::binary_search(Nodes.begin(), Nodes.begin() + NumHeaders, - Node); - return Node == Nodes[0]; - } + : Parent(Parent), IsPackaged(false), Nodes(1, Header) {} + bool isHeader(const BlockNode &Node) const { return Node == Nodes[0]; } BlockNode getHeader() const { return Nodes[0]; } - bool isIrreducible() const { return NumHeaders > 1; } - NodeList::const_iterator members_begin() const { - return Nodes.begin() + NumHeaders; - } + NodeList::const_iterator members_begin() const { return Nodes.begin() + 1; } NodeList::const_iterator members_end() const { return Nodes.end(); } iterator_range members() const { return make_range(members_begin(), members_end()); @@ -997,17 +975,9 @@ public: WorkingData(const BlockNode &Node) : Node(Node), Loop(nullptr) {} bool isLoopHeader() const { return Loop && Loop->isHeader(Node); } - bool isDoubleLoopHeader() const { - return isLoopHeader() && Loop->Parent && Loop->Parent->isIrreducible() && - Loop->Parent->isHeader(Node); - } LoopData *getContainingLoop() const { - if (!isLoopHeader()) - return Loop; - if (!isDoubleLoopHeader()) - return Loop->Parent; - return Loop->Parent->Parent; + return isLoopHeader() ? Loop->Parent : Loop; } /// \brief Resolve a node to its representative. @@ -1041,22 +1011,12 @@ public: /// Get appropriate mass for Node. If Node is a loop-header (whose loop /// has been packaged), returns the mass of its pseudo-node. If it's a /// node inside a packaged loop, it returns the loop's mass. - BlockMass &getMass() { - if (!isAPackage()) - return Mass; - if (!isADoublePackage()) - return Loop->Mass; - return Loop->Parent->Mass; - } + BlockMass &getMass() { return isAPackage() ? Loop->Mass : Mass; } /// \brief Has ContainingLoop been packaged up? bool isPackaged() const { return getResolvedNode() != Node; } /// \brief Has Loop been packaged up? bool isAPackage() const { return isLoopHeader() && Loop->IsPackaged; } - /// \brief Has Loop been packaged up twice? - bool isADoublePackage() const { - return isDoubleLoopHeader() && Loop->Parent->IsPackaged; - } }; /// \brief Unscaled probability weight. @@ -1133,9 +1093,7 @@ public: /// /// Adds all edges from LocalLoopHead to Dist. Calls addToDist() to add each /// successor edge. - /// - /// \return \c true unless there's an irreducible backedge. - bool addLoopSuccessorsToDist(const LoopData *OuterLoop, LoopData &Loop, + void addLoopSuccessorsToDist(const LoopData *OuterLoop, LoopData &Loop, Distribution &Dist); /// \brief Add an edge to the distribution. @@ -1143,9 +1101,7 @@ public: /// Adds an edge to Succ to Dist. If \c LoopHead.isValid(), then whether the /// edge is local/exit/backedge is in the context of LoopHead. Otherwise, /// every edge should be a local edge (since all the loops are packaged up). - /// - /// \return \c true unless aborted due to an irreducible backedge. - bool addToDist(Distribution &Dist, const LoopData *OuterLoop, + void addToDist(Distribution &Dist, const LoopData *OuterLoop, const BlockNode &Pred, const BlockNode &Succ, uint64_t Weight); LoopData &getLoopPackage(const BlockNode &Head) { @@ -1154,25 +1110,6 @@ public: return *Working[Head.Index].Loop; } - /// \brief Analyze irreducible SCCs. - /// - /// Separate irreducible SCCs from \c G, which is an explict graph of \c - /// OuterLoop (or the top-level function, if \c OuterLoop is \c nullptr). - /// Insert them into \a Loops before \c Insert. - /// - /// \return the \c LoopData nodes representing the irreducible SCCs. - iterator_range::iterator> - analyzeIrreducible(const bfi_detail::IrreducibleGraph &G, LoopData *OuterLoop, - std::list::iterator Insert); - - /// \brief Update a loop after packaging irreducible SCCs inside of it. - /// - /// Update \c OuterLoop. Before finding irreducible control flow, it was - /// partway through \a computeMassInLoop(), so \a LoopData::Exits and \a - /// LoopData::BackedgeMass need to be reset. Also, nodes that were packaged - /// up need to be removed from \a OuterLoop::Nodes. - void updateLoopWithIrreducible(LoopData &OuterLoop); - /// \brief Distribute mass according to a distribution. /// /// Distributes the mass in Source according to Dist. If LoopHead.isValid(), @@ -1201,7 +1138,6 @@ public: void clear(); virtual std::string getBlockName(const BlockNode &Node) const; - std::string getLoopName(const LoopData &Loop) const; virtual raw_ostream &print(raw_ostream &OS) const { return OS; } void dump() const { print(dbgs()); } @@ -1261,106 +1197,6 @@ template <> inline std::string getBlockName(const BasicBlock *BB) { assert(BB && "Unexpected nullptr"); return BB->getName().str(); } - -/// \brief Graph of irreducible control flow. -/// -/// This graph is used for determining the SCCs in a loop (or top-level -/// function) that has irreducible control flow. -/// -/// During the block frequency algorithm, the local graphs are defined in a -/// light-weight way, deferring to the \a BasicBlock or \a MachineBasicBlock -/// graphs for most edges, but getting others from \a LoopData::ExitMap. The -/// latter only has successor information. -/// -/// \a IrreducibleGraph makes this graph explicit. It's in a form that can use -/// \a GraphTraits (so that \a analyzeIrreducible() can use \a scc_iterator), -/// and it explicitly lists predecessors and successors. The initialization -/// that relies on \c MachineBasicBlock is defined in the header. -struct IrreducibleGraph { - typedef BlockFrequencyInfoImplBase BFIBase; - - BFIBase &BFI; - - typedef BFIBase::BlockNode BlockNode; - struct IrrNode { - BlockNode Node; - unsigned NumIn; - std::deque Edges; - IrrNode(const BlockNode &Node) : Node(Node), NumIn(0) {} - - typedef typename std::deque::const_iterator iterator; - iterator pred_begin() const { return Edges.begin(); } - iterator succ_begin() const { return Edges.begin() + NumIn; } - iterator pred_end() const { return succ_begin(); } - iterator succ_end() const { return Edges.end(); } - }; - BlockNode Start; - const IrrNode *StartIrr; - std::vector Nodes; - SmallDenseMap Lookup; - - /// \brief Construct an explicit graph containing irreducible control flow. - /// - /// Construct an explicit graph of the control flow in \c OuterLoop (or the - /// top-level function, if \c OuterLoop is \c nullptr). Uses \c - /// addBlockEdges to add block successors that have not been packaged into - /// loops. - /// - /// \a BlockFrequencyInfoImpl::computeIrreducibleMass() is the only expected - /// user of this. - template - IrreducibleGraph(BFIBase &BFI, const BFIBase::LoopData *OuterLoop, - BlockEdgesAdder addBlockEdges) - : BFI(BFI), StartIrr(nullptr) { - initialize(OuterLoop, addBlockEdges); - } - - template - void initialize(const BFIBase::LoopData *OuterLoop, - BlockEdgesAdder addBlockEdges); - void addNodesInLoop(const BFIBase::LoopData &OuterLoop); - void addNodesInFunction(); - void addNode(const BlockNode &Node) { - Nodes.emplace_back(Node); - BFI.Working[Node.Index].getMass() = BlockMass::getEmpty(); - } - void indexNodes(); - template - void addEdges(const BlockNode &Node, const BFIBase::LoopData *OuterLoop, - BlockEdgesAdder addBlockEdges); - void addEdge(IrrNode &Irr, const BlockNode &Succ, - const BFIBase::LoopData *OuterLoop); -}; -template -void IrreducibleGraph::initialize(const BFIBase::LoopData *OuterLoop, - BlockEdgesAdder addBlockEdges) { - if (OuterLoop) { - addNodesInLoop(*OuterLoop); - for (auto N : OuterLoop->Nodes) - addEdges(N, OuterLoop, addBlockEdges); - } else { - addNodesInFunction(); - for (uint32_t Index = 0; Index < BFI.Working.size(); ++Index) - addEdges(Index, OuterLoop, addBlockEdges); - } - StartIrr = Lookup[Start.Index]; -} -template -void IrreducibleGraph::addEdges(const BlockNode &Node, - const BFIBase::LoopData *OuterLoop, - BlockEdgesAdder addBlockEdges) { - auto L = Lookup.find(Node.Index); - if (L == Lookup.end()) - return; - IrrNode &Irr = *L->second; - const auto &Working = BFI.Working[Node.Index]; - - if (Working.isAPackage()) - for (const auto &I : Working.Loop->Exits) - addEdge(Irr, I.first, OuterLoop); - else - addBlockEdges(*this, Irr, OuterLoop); -} } /// \brief Shared implementation for block frequency analysis. @@ -1369,22 +1205,6 @@ void IrreducibleGraph::addEdges(const BlockNode &Node, /// MachineBlockFrequencyInfo, and calculates the relative frequencies of /// blocks. /// -/// LoopInfo defines a loop as a "non-trivial" SCC dominated by a single block, -/// which is called the header. A given loop, L, can have sub-loops, which are -/// loops within the subgraph of L that exclude its header. (A "trivial" SCC -/// consists of a single block that does not have a self-edge.) -/// -/// In addition to loops, this algorithm has limited support for irreducible -/// SCCs, which are SCCs with multiple entry blocks. Irreducible SCCs are -/// discovered on they fly, and modelled as loops with multiple headers. -/// -/// The headers of irreducible sub-SCCs consist of its entry blocks and all -/// nodes that are targets of a backedge within it (excluding backedges within -/// true sub-loops). Block frequency calculations act as if a block is -/// inserted that intercepts all the edges to the headers. All backedges and -/// entries point to this block. Its successors are the headers, which split -/// the frequency evenly. -/// /// This algorithm leverages BlockMass and UnsignedFloat to maintain precision, /// separates mass distribution from loop scaling, and dithers to eliminate /// probability mass loss. @@ -1408,7 +1228,7 @@ void IrreducibleGraph::addEdges(const BlockNode &Node, /// All other stages make use of this ordering. Save a lookup from BlockT /// to BlockNode (the index into RPOT) in Nodes. /// -/// 1. Loop initialization (\a initializeLoops()). +/// 1. Loop indexing (\a initializeLoops()). /// /// Translate LoopInfo/MachineLoopInfo into a form suitable for the rest of /// the algorithm. In particular, store the immediate members of each loop @@ -1419,9 +1239,11 @@ void IrreducibleGraph::addEdges(const BlockNode &Node, /// For each loop (bottom-up), distribute mass through the DAG resulting /// from ignoring backedges and treating sub-loops as a single pseudo-node. /// Track the backedge mass distributed to the loop header, and use it to -/// calculate the loop scale (number of loop iterations). Immediate -/// members that represent sub-loops will already have been visited and -/// packaged into a pseudo-node. +/// calculate the loop scale (number of loop iterations). +/// +/// Visiting loops bottom-up is a post-order traversal of loop headers. +/// For each loop, immediate members that represent sub-loops will already +/// have been visited and packaged into a pseudo-node. /// /// Distributing mass in a loop is a reverse-post-order traversal through /// the loop. Start by assigning full mass to the Loop header. For each @@ -1438,11 +1260,6 @@ void IrreducibleGraph::addEdges(const BlockNode &Node, /// The weight, the successor, and its category are stored in \a /// Distribution. There can be multiple edges to each successor. /// -/// - If there's a backedge to a non-header, there's an irreducible SCC. -/// The usual flow is temporarily aborted. \a -/// computeIrreducibleMass() finds the irreducible SCCs within the -/// loop, packages them up, and restarts the flow. -/// /// - Normalize the distribution: scale weights down so that their sum /// is 32-bits, and coalesce multiple edges to the same node. /// @@ -1457,62 +1274,39 @@ void IrreducibleGraph::addEdges(const BlockNode &Node, /// loops in the function. This uses the same algorithm as distributing /// mass in a loop, except that there are no exit or backedge edges. /// -/// 4. Unpackage loops (\a unwrapLoops()). +/// 4. Loop unpackaging and cleanup (\a finalizeMetrics()). /// -/// Initialize each block's frequency to a floating point representation of -/// its mass. +/// Initialize the frequency to a floating point representation of its +/// mass. /// -/// Visit loops top-down, scaling the frequencies of its immediate members -/// by the loop's pseudo-node's frequency. -/// -/// 5. Convert frequencies to a 64-bit range (\a finalizeMetrics()). +/// Visit loops top-down (reverse post-order), scaling the loop header's +/// frequency by its psuedo-node's mass and loop scale. Keep track of the +/// minimum and maximum final frequencies. /// /// Using the min and max frequencies as a guide, translate floating point /// frequencies to an appropriate range in uint64_t. /// /// It has some known flaws. /// -/// - Loop scale is limited to 4096 per loop (2^12) to avoid exhausting -/// BlockFrequency's 64-bit integer precision. -/// -/// - The model of irreducible control flow is a rough approximation. +/// - Irreducible control flow isn't modelled correctly. In particular, +/// LoopInfo and MachineLoopInfo ignore irreducible backedges. The main +/// result is that irreducible SCCs will under-scaled. No mass is lost, +/// but the computed branch weights for the loop pseudo-node will be +/// incorrect. /// /// Modelling irreducible control flow exactly involves setting up and /// solving a group of infinite geometric series. Such precision is /// unlikely to be worthwhile, since most of our algorithms give up on /// irreducible control flow anyway. /// -/// Nevertheless, we might find that we need to get closer. Here's a sort -/// of TODO list for the model with diminishing returns, to be completed as -/// necessary. +/// Nevertheless, we might find that we need to get closer. If +/// LoopInfo/MachineLoopInfo flags loops with irreducible control flow +/// (and/or the function as a whole), we can find the SCCs, compute an +/// approximate exit frequency for the SCC as a whole, and scale up +/// accordingly. /// -/// - The headers for the \a LoopData representing an irreducible SCC -/// include non-entry blocks. When these extra blocks exist, they -/// indicate a self-contained irreducible sub-SCC. We could treat them -/// as sub-loops, rather than arbitrarily shoving the problematic -/// blocks into the headers of the main irreducible SCC. -/// -/// - Backedge frequencies are assumed to be evenly split between the -/// headers of a given irreducible SCC. Instead, we could track the -/// backedge mass separately for each header, and adjust their relative -/// frequencies. -/// -/// - Entry frequencies are assumed to be evenly split between the -/// headers of a given irreducible SCC, which is the only option if we -/// need to compute mass in the SCC before its parent loop. Instead, -/// we could partially compute mass in the parent loop, and stop when -/// we get to the SCC. Here, we have the correct ratio of entry -/// masses, which we can use to adjust their relative frequencies. -/// Compute mass in the SCC, and then continue propagation in the -/// parent. -/// -/// - We can propagate mass iteratively through the SCC, for some fixed -/// number of iterations. Each iteration starts by assigning the entry -/// blocks their backedge mass from the prior iteration. The final -/// mass for each block (and each exit, and the total backedge mass -/// used for computing loop scale) is the sum of all iterations. -/// (Running this until fixed point would "solve" the geometric -/// series by simulation.) +/// - Loop scale is limited to 4096 per loop (2^12) to avoid exhausting +/// BlockFrequency's 64-bit integer precision. template class BlockFrequencyInfoImpl : BlockFrequencyInfoImplBase { typedef typename bfi_detail::TypeMap::BlockT BlockT; typedef typename bfi_detail::TypeMap::FunctionT FunctionT; @@ -1567,9 +1361,7 @@ template class BlockFrequencyInfoImpl : BlockFrequencyInfoImplBase { /// /// In the context of distributing mass through \c OuterLoop, divide the mass /// currently assigned to \c Node between its successors. - /// - /// \return \c true unless there's an irreducible backedge. - bool propagateMassToSuccessors(LoopData *OuterLoop, const BlockNode &Node); + void propagateMassToSuccessors(LoopData *OuterLoop, const BlockNode &Node); /// \brief Compute mass in a particular loop. /// @@ -1578,51 +1370,20 @@ template class BlockFrequencyInfoImpl : BlockFrequencyInfoImplBase { /// that have not been packaged into sub-loops. /// /// \pre \a computeMassInLoop() has been called for each subloop of \c Loop. - /// \return \c true unless there's an irreducible backedge. - bool computeMassInLoop(LoopData &Loop); + void computeMassInLoop(LoopData &Loop); - /// \brief Try to compute mass in the top-level function. + /// \brief Compute mass in all loops. + /// + /// For each loop bottom-up, call \a computeMassInLoop(). + void computeMassInLoops(); + + /// \brief Compute mass in the top-level function. /// /// Assign mass to the entry block, and then for each block in reverse /// post-order, distribute mass to its successors. Skips nodes that have /// been packaged into loops. /// /// \pre \a computeMassInLoops() has been called. - /// \return \c true unless there's an irreducible backedge. - bool tryToComputeMassInFunction(); - - /// \brief Compute mass in (and package up) irreducible SCCs. - /// - /// Find the irreducible SCCs in \c OuterLoop, add them to \a Loops (in front - /// of \c Insert), and call \a computeMassInLoop() on each of them. - /// - /// If \c OuterLoop is \c nullptr, it refers to the top-level function. - /// - /// \pre \a computeMassInLoop() has been called for each subloop of \c - /// OuterLoop. - /// \pre \c Insert points at the the last loop successfully processed by \a - /// computeMassInLoop(). - /// \pre \c OuterLoop has irreducible SCCs. - void computeIrreducibleMass(LoopData *OuterLoop, - std::list::iterator Insert); - - /// \brief Compute mass in all loops. - /// - /// For each loop bottom-up, call \a computeMassInLoop(). - /// - /// \a computeMassInLoop() aborts (and returns \c false) on loops that - /// contain a irreducible sub-SCCs. Use \a computeIrreducibleMass() and then - /// re-enter \a computeMassInLoop(). - /// - /// \post \a computeMassInLoop() has returned \c true for every loop. - void computeMassInLoops(); - - /// \brief Compute mass in the top-level function. - /// - /// Uses \a tryToComputeMassInFunction() and \a computeIrreducibleMass() to - /// compute mass in the top-level function. - /// - /// \post \a tryToComputeMassInFunction() has returned \c true. void computeMassInFunction(); std::string getBlockName(const BlockNode &Node) const override { @@ -1769,50 +1530,27 @@ template void BlockFrequencyInfoImpl::initializeLoops() { template void BlockFrequencyInfoImpl::computeMassInLoops() { // Visit loops with the deepest first, and the top-level loops last. - for (auto L = Loops.rbegin(), E = Loops.rend(); L != E; ++L) { - if (computeMassInLoop(*L)) - continue; - auto Next = std::next(L); - computeIrreducibleMass(&*L, L.base()); - L = std::prev(Next); - if (computeMassInLoop(*L)) - continue; - llvm_unreachable("unhandled irreducible control flow"); - } + for (auto L = Loops.rbegin(), E = Loops.rend(); L != E; ++L) + computeMassInLoop(*L); } template -bool BlockFrequencyInfoImpl::computeMassInLoop(LoopData &Loop) { +void BlockFrequencyInfoImpl::computeMassInLoop(LoopData &Loop) { // Compute mass in loop. - DEBUG(dbgs() << "compute-mass-in-loop: " << getLoopName(Loop) << "\n"); + DEBUG(dbgs() << "compute-mass-in-loop: " << getBlockName(Loop.getHeader()) + << "\n"); - if (Loop.isIrreducible()) { - BlockMass Remaining = BlockMass::getFull(); - for (uint32_t H = 0; H < Loop.NumHeaders; ++H) { - auto &Mass = Working[Loop.Nodes[H].Index].getMass(); - Mass = Remaining * BranchProbability(1, Loop.NumHeaders - H); - Remaining -= Mass; - } - for (const BlockNode &M : Loop.Nodes) - if (!propagateMassToSuccessors(&Loop, M)) - llvm_unreachable("unhandled irreducible control flow"); - } else { - Working[Loop.getHeader().Index].getMass() = BlockMass::getFull(); - if (!propagateMassToSuccessors(&Loop, Loop.getHeader())) - llvm_unreachable("irreducible control flow to loop header!?"); - for (const BlockNode &M : Loop.members()) - if (!propagateMassToSuccessors(&Loop, M)) - // Irreducible backedge. - return false; - } + Working[Loop.getHeader().Index].getMass() = BlockMass::getFull(); + propagateMassToSuccessors(&Loop, Loop.getHeader()); + + for (const BlockNode &M : Loop.members()) + propagateMassToSuccessors(&Loop, M); computeLoopScale(Loop); packageLoop(Loop); - return true; } -template -bool BlockFrequencyInfoImpl::tryToComputeMassInFunction() { +template void BlockFrequencyInfoImpl::computeMassInFunction() { // Compute mass in function. DEBUG(dbgs() << "compute-mass-in-function\n"); assert(!Working.empty() && "no blocks in function"); @@ -1825,48 +1563,12 @@ bool BlockFrequencyInfoImpl::tryToComputeMassInFunction() { if (Working[Node.Index].isPackaged()) continue; - if (!propagateMassToSuccessors(nullptr, Node)) - return false; + propagateMassToSuccessors(nullptr, Node); } - return true; -} - -template void BlockFrequencyInfoImpl::computeMassInFunction() { - if (tryToComputeMassInFunction()) - return; - computeIrreducibleMass(nullptr, Loops.begin()); - if (tryToComputeMassInFunction()) - return; - llvm_unreachable("unhandled irreducible control flow"); } template -void BlockFrequencyInfoImpl::computeIrreducibleMass( - LoopData *OuterLoop, std::list::iterator Insert) { - DEBUG(dbgs() << "analyze-irreducible-in-"; - if (OuterLoop) dbgs() << "loop: " << getLoopName(*OuterLoop) << "\n"; - else dbgs() << "function\n"); - - using bfi_detail::IrreducibleGraph; - auto addBlockEdges = [&](IrreducibleGraph &G, IrreducibleGraph::IrrNode &Irr, - const LoopData *OuterLoop) { - const BlockT *BB = RPOT[Irr.Node.Index]; - for (auto I = Successor::child_begin(BB), E = Successor::child_end(BB); - I != E; ++I) - G.addEdge(Irr, getNode(*I), OuterLoop); - }; - IrreducibleGraph G(*this, OuterLoop, addBlockEdges); - - for (auto &L : analyzeIrreducible(G, OuterLoop, Insert)) - computeMassInLoop(L); - - if (!OuterLoop) - return; - updateLoopWithIrreducible(*OuterLoop); -} - -template -bool +void BlockFrequencyInfoImpl::propagateMassToSuccessors(LoopData *OuterLoop, const BlockNode &Node) { DEBUG(dbgs() << " - node: " << getBlockName(Node) << "\n"); @@ -1874,25 +1576,20 @@ BlockFrequencyInfoImpl::propagateMassToSuccessors(LoopData *OuterLoop, Distribution Dist; if (auto *Loop = Working[Node.Index].getPackagedLoop()) { assert(Loop != OuterLoop && "Cannot propagate mass in a packaged loop"); - if (!addLoopSuccessorsToDist(OuterLoop, *Loop, Dist)) - // Irreducible backedge. - return false; + addLoopSuccessorsToDist(OuterLoop, *Loop, Dist); } else { const BlockT *BB = getBlock(Node); for (auto SI = Successor::child_begin(BB), SE = Successor::child_end(BB); SI != SE; ++SI) // Do not dereference SI, or getEdgeWeight() is linear in the number of // successors. - if (!addToDist(Dist, OuterLoop, Node, getNode(*SI), - BPI->getEdgeWeight(BB, SI))) - // Irreducible backedge. - return false; + addToDist(Dist, OuterLoop, Node, getNode(*SI), + BPI->getEdgeWeight(BB, SI)); } // Distribute mass to successors, saving exit and backedge data in the // loop header. distributeMass(Node, OuterLoop, Dist); - return true; } template diff --git a/lib/Analysis/BlockFrequencyInfoImpl.cpp b/lib/Analysis/BlockFrequencyInfoImpl.cpp index a12128318e2..2fcd9b8377b 100644 --- a/lib/Analysis/BlockFrequencyInfoImpl.cpp +++ b/lib/Analysis/BlockFrequencyInfoImpl.cpp @@ -17,7 +17,6 @@ #include using namespace llvm; -using namespace llvm::bfi_detail; #define DEBUG_TYPE "block-freq" @@ -569,7 +568,7 @@ static void cleanup(BlockFrequencyInfoImplBase &BFI) { BFI.Freqs = std::move(SavedFreqs); } -bool BlockFrequencyInfoImplBase::addToDist(Distribution &Dist, +void BlockFrequencyInfoImplBase::addToDist(Distribution &Dist, const LoopData *OuterLoop, const BlockNode &Pred, const BlockNode &Succ, @@ -599,48 +598,34 @@ bool BlockFrequencyInfoImplBase::addToDist(Distribution &Dist, if (isLoopHeader(Resolved)) { DEBUG(debugSuccessor("backedge")); Dist.addBackedge(OuterLoop->getHeader(), Weight); - return true; + return; } if (Working[Resolved.Index].getContainingLoop() != OuterLoop) { DEBUG(debugSuccessor(" exit ")); Dist.addExit(Resolved, Weight); - return true; + return; } if (Resolved < Pred) { - if (!isLoopHeader(Pred)) { - // If OuterLoop is an irreducible loop, we can't actually handle this. - assert((!OuterLoop || !OuterLoop->isIrreducible()) && - "unhandled irreducible control flow"); - - // Irreducible backedge. Abort. - DEBUG(debugSuccessor("abort!!!")); - return false; - } - - // If "Pred" is a loop header, then this isn't really a backedge; rather, - // OuterLoop must be irreducible. These false backedges can come only from - // secondary loop headers. - assert(OuterLoop && OuterLoop->isIrreducible() && !isLoopHeader(Resolved) && - "unhandled irreducible control flow"); + // Irreducible backedge. Skip. + DEBUG(debugSuccessor(" skip ")); + return; } DEBUG(debugSuccessor(" local ")); Dist.addLocal(Resolved, Weight); - return true; } -bool BlockFrequencyInfoImplBase::addLoopSuccessorsToDist( +void BlockFrequencyInfoImplBase::addLoopSuccessorsToDist( const LoopData *OuterLoop, LoopData &Loop, Distribution &Dist) { // Copy the exit map into Dist. for (const auto &I : Loop.Exits) - if (!addToDist(Dist, OuterLoop, Loop.getHeader(), I.first, - I.second.getMass())) - // Irreducible backedge. - return false; + addToDist(Dist, OuterLoop, Loop.getHeader(), I.first, I.second.getMass()); - return true; + // We don't need this map any more. Clear it to prevent quadratic memory + // usage in deeply nested loops with irreducible control flow. + Loop.Exits.clear(); } /// \brief Get the maximum allowed loop scale. @@ -652,7 +637,8 @@ static Float getMaxLoopScale() { return Float(1, 12); } /// \brief Compute the loop scale for a loop. void BlockFrequencyInfoImplBase::computeLoopScale(LoopData &Loop) { // Compute loop scale. - DEBUG(dbgs() << "compute-loop-scale: " << getLoopName(Loop) << "\n"); + DEBUG(dbgs() << "compute-loop-scale: " << getBlockName(Loop.getHeader()) + << "\n"); // LoopScale == 1 / ExitMass // ExitMass == HeadMass - BackedgeMass @@ -673,15 +659,12 @@ void BlockFrequencyInfoImplBase::computeLoopScale(LoopData &Loop) { /// \brief Package up a loop. void BlockFrequencyInfoImplBase::packageLoop(LoopData &Loop) { - DEBUG(dbgs() << "packaging-loop: " << getLoopName(Loop) << "\n"); - - // Clear the subloop exits to prevent quadratic memory usage. - for (const BlockNode &M : Loop.Nodes) { - if (auto *Loop = Working[M.Index].getPackagedLoop()) - Loop->Exits.clear(); - DEBUG(dbgs() << " - node: " << getBlockName(M.Index) << "\n"); - } + DEBUG(dbgs() << "packaging-loop: " << getBlockName(Loop.getHeader()) << "\n"); Loop.IsPackaged = true; + DEBUG(for (const BlockNode &M + : Loop.members()) { + dbgs() << " - node: " << getBlockName(M.Index) << "\n"; + }); } void BlockFrequencyInfoImplBase::distributeMass(const BlockNode &Source, @@ -762,7 +745,7 @@ static void convertFloatingToInteger(BlockFrequencyInfoImplBase &BFI, /// Visits all the members of a loop, adjusting their BlockData according to /// the loop's pseudo-node. static void unwrapLoop(BlockFrequencyInfoImplBase &BFI, LoopData &Loop) { - DEBUG(dbgs() << "unwrap-loop-package: " << BFI.getLoopName(Loop) + DEBUG(dbgs() << "unwrap-loop-package: " << BFI.getBlockName(Loop.getHeader()) << ": mass = " << Loop.Mass << ", scale = " << Loop.Scale << "\n"); Loop.Scale *= Loop.Mass.toFloat(); @@ -774,7 +757,7 @@ static void unwrapLoop(BlockFrequencyInfoImplBase &BFI, LoopData &Loop) { // final head scale will be used for updated the rest of the members. for (const BlockNode &N : Loop.Nodes) { const auto &Working = BFI.Working[N.Index]; - Float &F = Working.isAPackage() ? Working.getPackagedLoop()->Scale + Float &F = Working.isAPackage() ? BFI.getLoopPackage(N).Scale : BFI.Freqs[N.Index].Floating; Float New = Loop.Scale * F; DEBUG(dbgs() << " - " << BFI.getBlockName(N) << ": " << F << " => " << New @@ -830,10 +813,6 @@ std::string BlockFrequencyInfoImplBase::getBlockName(const BlockNode &Node) const { return std::string(); } -std::string -BlockFrequencyInfoImplBase::getLoopName(const LoopData &Loop) const { - return getBlockName(Loop.getHeader()) + (Loop.isIrreducible() ? "**" : "*"); -} raw_ostream & BlockFrequencyInfoImplBase::printBlockFreq(raw_ostream &OS, @@ -849,172 +828,3 @@ BlockFrequencyInfoImplBase::printBlockFreq(raw_ostream &OS, return OS << Block / Entry; } - -void IrreducibleGraph::addNodesInLoop(const BFIBase::LoopData &OuterLoop) { - Start = OuterLoop.getHeader(); - Nodes.reserve(OuterLoop.Nodes.size()); - for (auto N : OuterLoop.Nodes) - addNode(N); - indexNodes(); -} -void IrreducibleGraph::addNodesInFunction() { - Start = 0; - for (uint32_t Index = 0; Index < BFI.Working.size(); ++Index) - if (!BFI.Working[Index].isPackaged()) - addNode(Index); - indexNodes(); -} -void IrreducibleGraph::indexNodes() { - for (auto &I : Nodes) - Lookup[I.Node.Index] = &I; -} -void IrreducibleGraph::addEdge(IrrNode &Irr, const BlockNode &Succ, - const BFIBase::LoopData *OuterLoop) { - if (OuterLoop && OuterLoop->isHeader(Succ)) - return; - auto L = Lookup.find(Succ.Index); - if (L == Lookup.end()) - return; - IrrNode &SuccIrr = *L->second; - Irr.Edges.push_back(&SuccIrr); - SuccIrr.Edges.push_front(&Irr); - ++SuccIrr.NumIn; -} - -namespace llvm { -template <> struct GraphTraits { - typedef bfi_detail::IrreducibleGraph GraphT; - - typedef const typename GraphT::IrrNode NodeType; - typedef typename GraphT::IrrNode::iterator ChildIteratorType; - - static const NodeType *getEntryNode(const GraphT &G) { - return G.StartIrr; - } - static ChildIteratorType child_begin(NodeType *N) { return N->succ_begin(); } - static ChildIteratorType child_end(NodeType *N) { return N->succ_end(); } -}; -} - -/// \brief Find extra irreducible headers. -/// -/// Find entry blocks and other blocks with backedges, which exist when \c G -/// contains irreducible sub-SCCs. -static void findIrreducibleHeaders( - const BlockFrequencyInfoImplBase &BFI, - const IrreducibleGraph &G, - const std::vector &SCC, - LoopData::NodeList &Headers, LoopData::NodeList &Others) { - // Map from nodes in the SCC to whether it's an entry block. - SmallDenseMap InSCC; - - // InSCC also acts the set of nodes in the graph. Seed it. - for (const auto *I : SCC) - InSCC[I] = false; - - for (auto I = InSCC.begin(), E = InSCC.end(); I != E; ++I) { - auto &Irr = *I->first; - for (const auto *P : make_range(Irr.pred_begin(), Irr.pred_end())) { - if (InSCC.count(P)) - continue; - - // This is an entry block. - I->second = true; - Headers.push_back(Irr.Node); - DEBUG(dbgs() << " => entry = " << BFI.getBlockName(Irr.Node) << "\n"); - break; - } - } - assert(Headers.size() >= 2 && "Should be irreducible"); - if (Headers.size() == InSCC.size()) { - // Every block is a header. - std::sort(Headers.begin(), Headers.end()); - return; - } - - // Look for extra headers from irreducible sub-SCCs. - for (const auto &I : InSCC) { - // Entry blocks are already headers. - if (I.second) - continue; - - auto &Irr = *I.first; - for (const auto *P : make_range(Irr.pred_begin(), Irr.pred_end())) { - // Skip forward edges. - if (P->Node < Irr.Node) - continue; - - // Skip predecessors from entry blocks. These can have inverted - // ordering. - if (InSCC.lookup(P)) - continue; - - // Store the extra header. - Headers.push_back(Irr.Node); - DEBUG(dbgs() << " => extra = " << BFI.getBlockName(Irr.Node) << "\n"); - break; - } - if (Headers.back() == Irr.Node) - // Added this as a header. - continue; - - // This is not a header. - Others.push_back(Irr.Node); - DEBUG(dbgs() << " => other = " << BFI.getBlockName(Irr.Node) << "\n"); - } - std::sort(Headers.begin(), Headers.end()); - std::sort(Others.begin(), Others.end()); -} - -static void createIrreducibleLoop( - BlockFrequencyInfoImplBase &BFI, const IrreducibleGraph &G, - LoopData *OuterLoop, std::list::iterator Insert, - const std::vector &SCC) { - // Translate the SCC into RPO. - DEBUG(dbgs() << " - found-scc\n"); - - LoopData::NodeList Headers; - LoopData::NodeList Others; - findIrreducibleHeaders(BFI, G, SCC, Headers, Others); - - auto Loop = BFI.Loops.emplace(Insert, OuterLoop, Headers.begin(), - Headers.end(), Others.begin(), Others.end()); - - // Update loop hierarchy. - for (const auto &N : Loop->Nodes) - if (BFI.Working[N.Index].isLoopHeader()) - BFI.Working[N.Index].Loop->Parent = &*Loop; - else - BFI.Working[N.Index].Loop = &*Loop; -} - -iterator_range::iterator> -BlockFrequencyInfoImplBase::analyzeIrreducible( - const IrreducibleGraph &G, LoopData *OuterLoop, - std::list::iterator Insert) { - assert((OuterLoop == nullptr) == (Insert == Loops.begin())); - auto Prev = OuterLoop ? std::prev(Insert) : Loops.end(); - - for (auto I = scc_begin(G); !I.isAtEnd(); ++I) { - if (I->size() < 2) - continue; - - // Translate the SCC into RPO. - createIrreducibleLoop(*this, G, OuterLoop, Insert, *I); - } - - if (OuterLoop) - return make_range(std::next(Prev), Insert); - return make_range(Loops.begin(), Insert); -} - -void -BlockFrequencyInfoImplBase::updateLoopWithIrreducible(LoopData &OuterLoop) { - OuterLoop.Exits.clear(); - OuterLoop.BackedgeMass = BlockMass::getEmpty(); - auto O = OuterLoop.Nodes.begin() + 1; - for (auto I = O, E = OuterLoop.Nodes.end(); I != E; ++I) - if (!Working[I->Index].isPackaged()) - *O++ = *I; - OuterLoop.Nodes.erase(O, OuterLoop.Nodes.end()); -} diff --git a/test/Analysis/BlockFrequencyInfo/irreducible.ll b/test/Analysis/BlockFrequencyInfo/irreducible.ll index af4ad15d9c1..dd4dd9ed792 100644 --- a/test/Analysis/BlockFrequencyInfo/irreducible.ll +++ b/test/Analysis/BlockFrequencyInfo/irreducible.ll @@ -34,28 +34,16 @@ return: !0 = metadata !{metadata !"branch_weights", i32 1, i32 7} !1 = metadata !{metadata !"branch_weights", i32 3, i32 4} -; Irreducible control flow -; ======================== +; The current BlockFrequencyInfo algorithm doesn't handle multiple entrances +; into a loop very well. The frequencies assigned to blocks in the loop are +; predictable (and not absurd), but also not correct and therefore not worth +; testing. ; -; LoopInfo defines a loop as a non-trivial SCC dominated by a single block, -; called the header. A given loop, L, can have sub-loops, which are loops -; within the subgraph of L that excludes the header. +; There are two testcases below. ; -; In addition to loops, -block-freq has limited support for irreducible SCCs, -; which are SCCs with multiple entry blocks. Irreducible SCCs are discovered -; on they fly, and modelled as loops with multiple headers. -; -; The headers of irreducible sub-SCCs consist of its entry blocks and all nodes -; that are targets of a backedge within it (excluding backedges within true -; sub-loops). -; -; -block-freq is currently designed to act like a block is inserted that -; intercepts all the edges to the headers. All backedges and entries point to -; this block. Its successors are the headers, which split the frequency -; evenly. -; -; There are a number of testcases below. Only the first two have detailed -; explanations. +; For each testcase, I use a CHECK-NEXT/NOT combo like an XFAIL with the +; granularity of a single check. If/when this behaviour is fixed, we'll know +; about it, and the test should be updated. ; ; Testcase #1 ; =========== @@ -89,31 +77,36 @@ return: ; loop as a whole is 1/4, so the loop scale should be 4. Summing c1 and c2 ; gives 28/7, or 4.0, which is nice confirmation of the math above. ; -; -block-freq currently treats the two nodes as equals. -define void @multientry(i1 %x) { +; However, assuming c1 precedes c2 in reverse post-order, the current algorithm +; returns 3/4 and 13/16, respectively. LoopInfo ignores edges between loops +; (and doesn't see any loops here at all), and -block-freq ignores the +; irreducible edge from c2 to c1. +; ; CHECK-LABEL: Printing analysis {{.*}} for function 'multientry': ; CHECK-NEXT: block-frequency-info: multientry -entry: +define void @multientry(i1 %x) { ; CHECK-NEXT: entry: float = 1.0, int = [[ENTRY:[0-9]+]] +entry: br i1 %x, label %c1, label %c2, !prof !2 +; This is like a single-line XFAIL (see above). +; CHECK-NEXT: c1: +; CHECK-NOT: float = 2.142857{{[0-9]*}}, c1: -; CHECK-NEXT: c1: float = 2.0, -; The "correct" answer is: float = 2.142857{{[0-9]*}}, br i1 %x, label %c2, label %exit, !prof !2 +; This is like a single-line XFAIL (see above). +; CHECK-NEXT: c2: +; CHECK-NOT: float = 1.857142{{[0-9]*}}, c2: -; CHECK-NEXT: c2: float = 2.0, -; The "correct" answer is: float = 1.857142{{[0-9]*}}, br i1 %x, label %c1, label %exit, !prof !2 -exit: +; We still shouldn't lose any frequency. ; CHECK-NEXT: exit: float = 1.0, int = [[ENTRY]] +exit: ret void } -!2 = metadata !{metadata !"branch_weights", i32 3, i32 1} - ; Testcase #2 ; =========== ; @@ -131,291 +124,73 @@ exit: ; step, c1 and c2 each get 1/3 of what's left in c1 and c2 combined. This ; infinite series sums to 1. ; -; Since the currently algorithm *always* assumes entry blocks are equal, -; -block-freq gets the right answers here. -define void @crossloops(i2 %x) { +; However, assuming c1 precedes c2 in reverse post-order, the current algorithm +; returns 1/2 and 3/4, respectively. LoopInfo ignores edges between loops (and +; treats c1 and c2 as self-loops only), and -block-freq ignores the irreducible +; edge from c2 to c1. +; +; Below I use a CHECK-NEXT/NOT combo like an XFAIL with the granularity of a +; single check. If/when this behaviour is fixed, we'll know about it, and the +; test should be updated. +; ; CHECK-LABEL: Printing analysis {{.*}} for function 'crossloops': ; CHECK-NEXT: block-frequency-info: crossloops -entry: +define void @crossloops(i2 %x) { ; CHECK-NEXT: entry: float = 1.0, int = [[ENTRY:[0-9]+]] +entry: switch i2 %x, label %exit [ i2 1, label %c1 i2 2, label %c2 ], !prof !3 +; This is like a single-line XFAIL (see above). +; CHECK-NEXT: c1: +; CHECK-NOT: float = 1.0, c1: -; CHECK-NEXT: c1: float = 1.0, switch i2 %x, label %exit [ i2 1, label %c1 i2 2, label %c2 ], !prof !3 +; This is like a single-line XFAIL (see above). +; CHECK-NEXT: c2: +; CHECK-NOT: float = 1.0, c2: -; CHECK-NEXT: c2: float = 1.0, switch i2 %x, label %exit [ i2 1, label %c1 i2 2, label %c2 ], !prof !3 -exit: +; We still shouldn't lose any frequency. ; CHECK-NEXT: exit: float = 1.0, int = [[ENTRY]] +exit: ret void } +!2 = metadata !{metadata !"branch_weights", i32 3, i32 1} !3 = metadata !{metadata !"branch_weights", i32 2, i32 2, i32 2} -; A true loop with irreducible control flow inside. -define void @loop_around_irreducible(i1 %x) { +; A reducible loop with irreducible control flow inside should still have +; correct exit frequency. +; ; CHECK-LABEL: Printing analysis {{.*}} for function 'loop_around_irreducible': ; CHECK-NEXT: block-frequency-info: loop_around_irreducible -entry: +define void @loop_around_irreducible(i1 %x) { ; CHECK-NEXT: entry: float = 1.0, int = [[ENTRY:[0-9]+]] +entry: br label %loop +; CHECK-NEXT: loop: float = [[HEAD:[0-9.]+]], int = [[HEADINT:[0-9]+]] loop: -; CHECK-NEXT: loop: float = 4.0, int = [[HEAD:[0-9]+]] - br i1 %x, label %left, label %right, !prof !4 + br i1 %x, label %left, label %right +; CHECK-NEXT: left: left: -; CHECK-NEXT: left: float = 8.0, - br i1 %x, label %right, label %loop.end, !prof !5 + br i1 %x, label %right, label %loop.end +; CHECK-NEXT: right: right: -; CHECK-NEXT: right: float = 8.0, - br i1 %x, label %left, label %loop.end, !prof !5 + br i1 %x, label %left, label %loop.end +; CHECK-NEXT: loop.end: float = [[HEAD]], int = [[HEADINT]] loop.end: -; CHECK-NEXT: loop.end: float = 4.0, int = [[HEAD]] - br i1 %x, label %loop, label %exit, !prof !5 + br i1 %x, label %loop, label %exit +; CHECK-NEXT: float = 1.0, int = [[ENTRY]] exit: -; CHECK-NEXT: exit: float = 1.0, int = [[ENTRY]] ret void } -!4 = metadata !{metadata !"branch_weights", i32 1, i32 1} -!5 = metadata !{metadata !"branch_weights", i32 3, i32 1} - -; Two unrelated irreducible SCCs. -define void @two_sccs(i1 %x) { -; CHECK-LABEL: Printing analysis {{.*}} for function 'two_sccs': -; CHECK-NEXT: block-frequency-info: two_sccs -entry: -; CHECK-NEXT: entry: float = 1.0, int = [[ENTRY:[0-9]+]] - br i1 %x, label %a, label %b, !prof !6 - -a: -; CHECK-NEXT: a: float = 0.75, - br i1 %x, label %a.left, label %a.right, !prof !7 - -a.left: -; CHECK-NEXT: a.left: float = 1.5, - br i1 %x, label %a.right, label %exit, !prof !6 - -a.right: -; CHECK-NEXT: a.right: float = 1.5, - br i1 %x, label %a.left, label %exit, !prof !6 - -b: -; CHECK-NEXT: b: float = 0.25, - br i1 %x, label %b.left, label %b.right, !prof !7 - -b.left: -; CHECK-NEXT: b.left: float = 0.625, - br i1 %x, label %b.right, label %exit, !prof !8 - -b.right: -; CHECK-NEXT: b.right: float = 0.625, - br i1 %x, label %b.left, label %exit, !prof !8 - -exit: -; CHECK-NEXT: exit: float = 1.0, int = [[ENTRY]] - ret void -} -!6 = metadata !{metadata !"branch_weights", i32 3, i32 1} -!7 = metadata !{metadata !"branch_weights", i32 1, i32 1} -!8 = metadata !{metadata !"branch_weights", i32 4, i32 1} - -; A true loop inside irreducible control flow. -define void @loop_inside_irreducible(i1 %x) { -; CHECK-LABEL: Printing analysis {{.*}} for function 'loop_inside_irreducible': -; CHECK-NEXT: block-frequency-info: loop_inside_irreducible -entry: -; CHECK-NEXT: entry: float = 1.0, int = [[ENTRY:[0-9]+]] - br i1 %x, label %left, label %right, !prof !9 - -left: -; CHECK-NEXT: left: float = 2.0, - br i1 %x, label %right, label %exit, !prof !10 - -right: -; CHECK-NEXT: right: float = 2.0, int = [[RIGHT:[0-9]+]] - br label %loop - -loop: -; CHECK-NEXT: loop: float = 6.0, - br i1 %x, label %loop, label %right.end, !prof !11 - -right.end: -; CHECK-NEXT: right.end: float = 2.0, int = [[RIGHT]] - br i1 %x, label %left, label %exit, !prof !10 - -exit: -; CHECK-NEXT: exit: float = 1.0, int = [[ENTRY]] - ret void -} -!9 = metadata !{metadata !"branch_weights", i32 1, i32 1} -!10 = metadata !{metadata !"branch_weights", i32 3, i32 1} -!11 = metadata !{metadata !"branch_weights", i32 2, i32 1} - -; Irreducible control flow in a branch that's in a true loop. -define void @loop_around_branch_with_irreducible(i1 %x) { -; CHECK-LABEL: Printing analysis {{.*}} for function 'loop_around_branch_with_irreducible': -; CHECK-NEXT: block-frequency-info: loop_around_branch_with_irreducible -entry: -; CHECK-NEXT: entry: float = 1.0, int = [[ENTRY:[0-9]+]] - br label %loop - -loop: -; CHECK-NEXT: loop: float = 2.0, int = [[LOOP:[0-9]+]] - br i1 %x, label %normal, label %irreducible.entry, !prof !12 - -normal: -; CHECK-NEXT: normal: float = 1.5, - br label %loop.end - -irreducible.entry: -; CHECK-NEXT: irreducible.entry: float = 0.5, int = [[IRREDUCIBLE:[0-9]+]] - br i1 %x, label %left, label %right, !prof !13 - -left: -; CHECK-NEXT: left: float = 1.0, - br i1 %x, label %right, label %irreducible.exit, !prof !12 - -right: -; CHECK-NEXT: right: float = 1.0, - br i1 %x, label %left, label %irreducible.exit, !prof !12 - -irreducible.exit: -; CHECK-NEXT: irreducible.exit: float = 0.5, int = [[IRREDUCIBLE]] - br label %loop.end - -loop.end: -; CHECK-NEXT: loop.end: float = 2.0, int = [[LOOP]] - br i1 %x, label %loop, label %exit, !prof !13 - -exit: -; CHECK-NEXT: exit: float = 1.0, int = [[ENTRY]] - ret void -} -!12 = metadata !{metadata !"branch_weights", i32 3, i32 1} -!13 = metadata !{metadata !"branch_weights", i32 1, i32 1} - -; Irreducible control flow between two true loops. -define void @loop_around_branch_with_irreducible_around_loop(i1 %x) { -; CHECK-LABEL: Printing analysis {{.*}} for function 'loop_around_branch_with_irreducible_around_loop': -; CHECK-NEXT: block-frequency-info: loop_around_branch_with_irreducible_around_loop -entry: -; CHECK-NEXT: entry: float = 1.0, int = [[ENTRY:[0-9]+]] - br label %loop - -loop: -; CHECK-NEXT: loop: float = 3.0, int = [[LOOP:[0-9]+]] - br i1 %x, label %normal, label %irreducible, !prof !14 - -normal: -; CHECK-NEXT: normal: float = 2.0, - br label %loop.end - -irreducible: -; CHECK-NEXT: irreducible: float = 1.0, - br i1 %x, label %left, label %right, !prof !15 - -left: -; CHECK-NEXT: left: float = 2.0, - br i1 %x, label %right, label %loop.end, !prof !16 - -right: -; CHECK-NEXT: right: float = 2.0, int = [[RIGHT:[0-9]+]] - br label %right.loop - -right.loop: -; CHECK-NEXT: right.loop: float = 10.0, - br i1 %x, label %right.loop, label %right.end, !prof !17 - -right.end: -; CHECK-NEXT: right.end: float = 2.0, int = [[RIGHT]] - br i1 %x, label %left, label %loop.end, !prof !16 - -loop.end: -; CHECK-NEXT: loop.end: float = 3.0, int = [[LOOP]] - br i1 %x, label %loop, label %exit, !prof !14 - -exit: -; CHECK-NEXT: exit: float = 1.0, int = [[ENTRY]] - ret void -} -!14 = metadata !{metadata !"branch_weights", i32 2, i32 1} -!15 = metadata !{metadata !"branch_weights", i32 1, i32 1} -!16 = metadata !{metadata !"branch_weights", i32 3, i32 1} -!17 = metadata !{metadata !"branch_weights", i32 4, i32 1} - -; An irreducible SCC with a non-header. -define void @nonheader(i1 %x) { -; CHECK-LABEL: Printing analysis {{.*}} for function 'nonheader': -; CHECK-NEXT: block-frequency-info: nonheader -entry: -; CHECK-NEXT: entry: float = 1.0, int = [[ENTRY:[0-9]+]] - br i1 %x, label %left, label %right, !prof !18 - -left: -; CHECK-NEXT: left: float = 1.0, - br i1 %x, label %bottom, label %exit, !prof !19 - -right: -; CHECK-NEXT: right: float = 1.0, - br i1 %x, label %bottom, label %exit, !prof !20 - -bottom: -; CHECK-NEXT: bottom: float = 1.0, - br i1 %x, label %left, label %right, !prof !18 - -exit: -; CHECK-NEXT: exit: float = 1.0, int = [[ENTRY]] - ret void -} -!18 = metadata !{metadata !"branch_weights", i32 1, i32 1} -!19 = metadata !{metadata !"branch_weights", i32 1, i32 3} -!20 = metadata !{metadata !"branch_weights", i32 3, i32 1} - -; An irreducible SCC with an irreducible sub-SCC. In the current version of -; -block-freq, this means an extra header. -; -; This testcases uses non-trivial branch weights. The CHECK statements here -; will start to fail if we change -block-freq to be more accurate. Currently, -; we expect left, right and top to be treated as equal headers. -define void @nonentry_header(i1 %x, i2 %y) { -; CHECK-LABEL: Printing analysis {{.*}} for function 'nonentry_header': -; CHECK-NEXT: block-frequency-info: nonentry_header -entry: -; CHECK-NEXT: entry: float = 1.0, int = [[ENTRY:[0-9]+]] - br i1 %x, label %left, label %right, !prof !21 - -left: -; CHECK-NEXT: left: float = 3.0, - br i1 %x, label %top, label %bottom, !prof !22 - -right: -; CHECK-NEXT: right: float = 3.0, - br i1 %x, label %top, label %bottom, !prof !22 - -top: -; CHECK-NEXT: top: float = 3.0, - switch i2 %y, label %exit [ i2 0, label %left - i2 1, label %right - i2 2, label %bottom ], !prof !23 - -bottom: -; CHECK-NEXT: bottom: float = 4.5, - br label %top - -exit: -; CHECK-NEXT: exit: float = 1.0, int = [[ENTRY]] - ret void -} -!21 = metadata !{metadata !"branch_weights", i32 2, i32 1} -!22 = metadata !{metadata !"branch_weights", i32 1, i32 1} -!23 = metadata !{metadata !"branch_weights", i32 8, i32 1, i32 3, i32 12}