//===----------------------------------------------------------------------===//
//
// Shared implementation of BlockFrequency for IR and Machine Instructions.
-// See the documentation below for BlockFrequencyInfoImpl for details.
//
//===----------------------------------------------------------------------===//
#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"
class MachineLoop;
class MachineLoopInfo;
-namespace bfi_detail {
-struct IrreducibleGraph;
-}
-
/// \brief Base class for BlockFrequencyInfoImpl
///
/// BlockFrequencyInfoImplBase has supporting data structures and some
typedef SmallVector<BlockNode, 4> 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.
Float Scale;
LoopData(LoopData *Parent, const BlockNode &Header)
- : Parent(Parent), IsPackaged(false), NumHeaders(1), Nodes(1, Header) {}
- template <class It1, class It2>
- 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<NodeList::const_iterator> members() const {
return make_range(members_begin(), members_end());
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.
/// 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.
///
/// 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.
/// 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) {
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<std::list<LoopData>::iterator>
- analyzeIrreducible(const bfi_detail::IrreducibleGraph &G, LoopData *OuterLoop,
- std::list<LoopData>::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(),
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()); }
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<const IrrNode *> Edges;
- IrrNode(const BlockNode &Node) : Node(Node), NumIn(0) {}
-
- typedef typename std::deque<const IrrNode *>::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<IrrNode> Nodes;
- SmallDenseMap<uint32_t, IrrNode *, 4> 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 <class BlockEdgesAdder>
- IrreducibleGraph(BFIBase &BFI, const BFIBase::LoopData *OuterLoop,
- BlockEdgesAdder addBlockEdges)
- : BFI(BFI), StartIrr(nullptr) {
- initialize(OuterLoop, addBlockEdges);
- }
-
- template <class BlockEdgesAdder>
- 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 <class BlockEdgesAdder>
- void addEdges(const BlockNode &Node, const BFIBase::LoopData *OuterLoop,
- BlockEdgesAdder addBlockEdges);
- void addEdge(IrrNode &Irr, const BlockNode &Succ,
- const BFIBase::LoopData *OuterLoop);
-};
-template <class BlockEdgesAdder>
-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 <class BlockEdgesAdder>
-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.
/// 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.
/// 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
/// 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
/// 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.
///
/// 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()).
-///
-/// Initialize each block's frequency to a floating point representation of
-/// its mass.
+/// 4. Loop unpackaging and cleanup (\a finalizeMetrics()).
///
-/// Visit loops top-down, scaling the frequencies of its immediate members
-/// by the loop's pseudo-node's frequency.
+/// Initialize the frequency to a floating point representation of its
+/// mass.
///
-/// 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.
-///
-/// - 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.
+/// 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.
///
-/// - 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 BT> class BlockFrequencyInfoImpl : BlockFrequencyInfoImplBase {
typedef typename bfi_detail::TypeMap<BT>::BlockT BlockT;
typedef typename bfi_detail::TypeMap<BT>::FunctionT FunctionT;
///
/// 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.
///
/// 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);
-
- /// \brief Try to 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<LoopData>::iterator Insert);
+ void computeMassInLoop(LoopData &Loop);
/// \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.
+ /// 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.
///
- /// \post \a tryToComputeMassInFunction() has returned \c true.
+ /// \pre \a computeMassInLoops() has been called.
void computeMassInFunction();
std::string getBlockName(const BlockNode &Node) const override {
template <class BT> void BlockFrequencyInfoImpl<BT>::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 <class BT>
-bool BlockFrequencyInfoImpl<BT>::computeMassInLoop(LoopData &Loop) {
+void BlockFrequencyInfoImpl<BT>::computeMassInLoop(LoopData &Loop) {
// Compute mass in loop.
- DEBUG(dbgs() << "compute-mass-in-loop: " << getLoopName(Loop) << "\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;
- }
+ DEBUG(dbgs() << "compute-mass-in-loop: " << getBlockName(Loop.getHeader())
+ << "\n");
+
+ 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 <class BT>
-bool BlockFrequencyInfoImpl<BT>::tryToComputeMassInFunction() {
+template <class BT> void BlockFrequencyInfoImpl<BT>::computeMassInFunction() {
// Compute mass in function.
DEBUG(dbgs() << "compute-mass-in-function\n");
assert(!Working.empty() && "no blocks in function");
if (Working[Node.Index].isPackaged())
continue;
- if (!propagateMassToSuccessors(nullptr, Node))
- return false;
+ propagateMassToSuccessors(nullptr, Node);
}
- return true;
-}
-
-template <class BT> void BlockFrequencyInfoImpl<BT>::computeMassInFunction() {
- if (tryToComputeMassInFunction())
- return;
- computeIrreducibleMass(nullptr, Loops.begin());
- if (tryToComputeMassInFunction())
- return;
- llvm_unreachable("unhandled irreducible control flow");
}
template <class BT>
-void BlockFrequencyInfoImpl<BT>::computeIrreducibleMass(
- LoopData *OuterLoop, std::list<LoopData>::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 <class BT>
-bool
+void
BlockFrequencyInfoImpl<BT>::propagateMassToSuccessors(LoopData *OuterLoop,
const BlockNode &Node) {
DEBUG(dbgs() << " - node: " << getBlockName(Node) << "\n");
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 <class BT>
#include <deque>
using namespace llvm;
-using namespace llvm::bfi_detail;
#define DEBUG_TYPE "block-freq"
BFI.Freqs = std::move(SavedFreqs);
}
-bool BlockFrequencyInfoImplBase::addToDist(Distribution &Dist,
+void BlockFrequencyInfoImplBase::addToDist(Distribution &Dist,
const LoopData *OuterLoop,
const BlockNode &Pred,
const BlockNode &Succ,
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.
/// \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
/// \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,
/// 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();
// 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
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,
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<IrreducibleGraph> {
- 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<const IrreducibleGraph::IrrNode *> &SCC,
- LoopData::NodeList &Headers, LoopData::NodeList &Others) {
- // Map from nodes in the SCC to whether it's an entry block.
- SmallDenseMap<const IrreducibleGraph::IrrNode *, bool, 8> 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<LoopData>::iterator Insert,
- const std::vector<const IrreducibleGraph::IrrNode *> &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<std::list<LoopData>::iterator>
-BlockFrequencyInfoImplBase::analyzeIrreducible(
- const IrreducibleGraph &G, LoopData *OuterLoop,
- std::list<LoopData>::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());
-}
!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
; ===========
; 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
; ===========
;
; 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:
-; CHECK-NEXT: entry: float = 1.0, int = [[ENTRY:[0-9]+]]
- br label %loop
-
-loop:
-; CHECK-NEXT: loop: float = 4.0, int = [[HEAD:[0-9]+]]
- br i1 %x, label %left, label %right, !prof !4
-
-left:
-; CHECK-NEXT: left: float = 8.0,
- br i1 %x, label %right, label %loop.end, !prof !5
-
-right:
-; CHECK-NEXT: right: float = 8.0,
- br i1 %x, label %left, label %loop.end, !prof !5
-
-loop.end:
-; CHECK-NEXT: loop.end: float = 4.0, int = [[HEAD]]
- br i1 %x, label %loop, label %exit, !prof !5
-
-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:
+define void @loop_around_irreducible(i1 %x) {
; 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
+; CHECK-NEXT: loop: float = [[HEAD:[0-9.]+]], int = [[HEADINT:[0-9]+]]
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
+ br i1 %x, label %left, label %right
+; CHECK-NEXT: left:
left:
-; CHECK-NEXT: left: float = 2.0,
- br i1 %x, label %right, label %loop.end, !prof !16
+ br i1 %x, label %right, label %loop.end
+; CHECK-NEXT: right:
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
+ br i1 %x, label %left, label %loop.end
+; CHECK-NEXT: loop.end: float = [[HEAD]], int = [[HEADINT]]
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
+ 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
-}
-!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}
projects / oota-llvm.git / commitdiff