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+//===- LazyCallGraph.h - Analysis of a Module's call graph ------*- C++ -*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+/// \file
+///
+/// Implements a lazy call graph analysis and related passes for the new pass
+/// manager.
+///
+/// NB: This is *not* a traditional call graph! It is a graph which models both
+/// the current calls and potential calls. As a consequence there are many
+/// edges in this call graph that do not correspond to a 'call' or 'invoke'
+/// instruction.
+///
+/// The primary use cases of this graph analysis is to facilitate iterating
+/// across the functions of a module in ways that ensure all callees are
+/// visited prior to a caller (given any SCC constraints), or vice versa. As
+/// such is it particularly well suited to organizing CGSCC optimizations such
+/// as inlining, outlining, argument promotion, etc. That is its primary use
+/// case and motivates the design. It may not be appropriate for other
+/// purposes. The use graph of functions or some other conservative analysis of
+/// call instructions may be interesting for optimizations and subsequent
+/// analyses which don't work in the context of an overly specified
+/// potential-call-edge graph.
+///
+/// To understand the specific rules and nature of this call graph analysis,
+/// see the documentation of the \c LazyCallGraph below.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_ANALYSIS_LAZYCALLGRAPH_H
+#define LLVM_ANALYSIS_LAZYCALLGRAPH_H
+
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/Optional.h"
+#include "llvm/ADT/PointerIntPair.h"
+#include "llvm/ADT/SetVector.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/ADT/iterator.h"
+#include "llvm/ADT/iterator_range.h"
+#include "llvm/Analysis/TargetLibraryInfo.h"
+#include "llvm/IR/Constant.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/PassManager.h"
+#include "llvm/Support/Allocator.h"
+#include "llvm/Support/Casting.h"
+#include "llvm/Support/raw_ostream.h"
+#include <cassert>
+#include <iterator>
+#include <string>
+#include <utility>
+
+namespace llvm {
+
+class Module;
+class Value;
+
+/// A lazily constructed view of the call graph of a module.
+///
+/// With the edges of this graph, the motivating constraint that we are
+/// attempting to maintain is that function-local optimization, CGSCC-local
+/// optimizations, and optimizations transforming a pair of functions connected
+/// by an edge in the graph, do not invalidate a bottom-up traversal of the SCC
+/// DAG. That is, no optimizations will delete, remove, or add an edge such
+/// that functions already visited in a bottom-up order of the SCC DAG are no
+/// longer valid to have visited, or such that functions not yet visited in
+/// a bottom-up order of the SCC DAG are not required to have already been
+/// visited.
+///
+/// Within this constraint, the desire is to minimize the merge points of the
+/// SCC DAG. The greater the fanout of the SCC DAG and the fewer merge points
+/// in the SCC DAG, the more independence there is in optimizing within it.
+/// There is a strong desire to enable parallelization of optimizations over
+/// the call graph, and both limited fanout and merge points will (artificially
+/// in some cases) limit the scaling of such an effort.
+///
+/// To this end, graph represents both direct and any potential resolution to
+/// an indirect call edge. Another way to think about it is that it represents
+/// both the direct call edges and any direct call edges that might be formed
+/// through static optimizations. Specifically, it considers taking the address
+/// of a function to be an edge in the call graph because this might be
+/// forwarded to become a direct call by some subsequent function-local
+/// optimization. The result is that the graph closely follows the use-def
+/// edges for functions. Walking "up" the graph can be done by looking at all
+/// of the uses of a function.
+///
+/// The roots of the call graph are the external functions and functions
+/// escaped into global variables. Those functions can be called from outside
+/// of the module or via unknowable means in the IR -- we may not be able to
+/// form even a potential call edge from a function body which may dynamically
+/// load the function and call it.
+///
+/// This analysis still requires updates to remain valid after optimizations
+/// which could potentially change the set of potential callees. The
+/// constraints it operates under only make the traversal order remain valid.
+///
+/// The entire analysis must be re-computed if full interprocedural
+/// optimizations run at any point. For example, globalopt completely
+/// invalidates the information in this analysis.
+///
+/// FIXME: This class is named LazyCallGraph in a lame attempt to distinguish
+/// it from the existing CallGraph. At some point, it is expected that this
+/// will be the only call graph and it will be renamed accordingly.
+class LazyCallGraph {
+public:
+ class Node;
+ class EdgeSequence;
+ class SCC;
+ class RefSCC;
+ class edge_iterator;
+ class call_edge_iterator;
+
+ /// A class used to represent edges in the call graph.
+ ///
+ /// The lazy call graph models both *call* edges and *reference* edges. Call
+ /// edges are much what you would expect, and exist when there is a 'call' or
+ /// 'invoke' instruction of some function. Reference edges are also tracked
+ /// along side these, and exist whenever any instruction (transitively
+ /// through its operands) references a function. All call edges are
+ /// inherently reference edges, and so the reference graph forms a superset
+ /// of the formal call graph.
+ ///
+ /// All of these forms of edges are fundamentally represented as outgoing
+ /// edges. The edges are stored in the source node and point at the target
+ /// node. This allows the edge structure itself to be a very compact data
+ /// structure: essentially a tagged pointer.
+ class Edge {
+ public:
+ /// The kind of edge in the graph.
+ enum Kind : bool { Ref = false, Call = true };
+
+ Edge();
+ explicit Edge(Node &N, Kind K);
+
+ /// Test whether the edge is null.
+ ///
+ /// This happens when an edge has been deleted. We leave the edge objects
+ /// around but clear them.
+ explicit operator bool() const;
+
+ /// Returnss the \c Kind of the edge.
+ Kind getKind() const;
+
+ /// Test whether the edge represents a direct call to a function.
+ ///
+ /// This requires that the edge is not null.
+ bool isCall() const;
+
+ /// Get the call graph node referenced by this edge.
+ ///
+ /// This requires that the edge is not null.
+ Node &getNode() const;
+
+ /// Get the function referenced by this edge.
+ ///
+ /// This requires that the edge is not null.
+ Function &getFunction() const;
+
+ private:
+ friend class LazyCallGraph::EdgeSequence;
+ friend class LazyCallGraph::RefSCC;
+
+ PointerIntPair<Node *, 1, Kind> Value;
+
+ void setKind(Kind K) { Value.setInt(K); }
+ };
+
+ /// The edge sequence object.
+ ///
+ /// This typically exists entirely within the node but is exposed as
+ /// a separate type because a node doesn't initially have edges. An explicit
+ /// population step is required to produce this sequence at first and it is
+ /// then cached in the node. It is also used to represent edges entering the
+ /// graph from outside the module to model the graph's roots.
+ ///
+ /// The sequence itself both iterable and indexable. The indexes remain
+ /// stable even as the sequence mutates (including removal).
+ class EdgeSequence {
+ friend class LazyCallGraph;
+ friend class LazyCallGraph::Node;
+ friend class LazyCallGraph::RefSCC;
+
+ using VectorT = SmallVector<Edge, 4>;
+ using VectorImplT = SmallVectorImpl<Edge>;
+
+ public:
+ /// An iterator used for the edges to both entry nodes and child nodes.
+ class iterator
+ : public iterator_adaptor_base<iterator, VectorImplT::iterator,
+ std::forward_iterator_tag> {
+ friend class LazyCallGraph;
+ friend class LazyCallGraph::Node;
+
+ VectorImplT::iterator E;
+
+ // Build the iterator for a specific position in the edge list.
+ iterator(VectorImplT::iterator BaseI, VectorImplT::iterator E)
+ : iterator_adaptor_base(BaseI), E(E) {
+ while (I != E && !*I)
+ ++I;
+ }
+
+ public:
+ iterator() = default;
+
+ using iterator_adaptor_base::operator++;
+ iterator &operator++() {
+ do {
+ ++I;
+ } while (I != E && !*I);
+ return *this;
+ }
+ };
+
+ /// An iterator over specifically call edges.
+ ///
+ /// This has the same iteration properties as the \c iterator, but
+ /// restricts itself to edges which represent actual calls.
+ class call_iterator
+ : public iterator_adaptor_base<call_iterator, VectorImplT::iterator,
+ std::forward_iterator_tag> {
+ friend class LazyCallGraph;
+ friend class LazyCallGraph::Node;
+
+ VectorImplT::iterator E;
+
+ /// Advance the iterator to the next valid, call edge.
+ void advanceToNextEdge() {
+ while (I != E && (!*I || !I->isCall()))
+ ++I;
+ }
+
+ // Build the iterator for a specific position in the edge list.
+ call_iterator(VectorImplT::iterator BaseI, VectorImplT::iterator E)
+ : iterator_adaptor_base(BaseI), E(E) {
+ advanceToNextEdge();
+ }
+
+ public:
+ call_iterator() = default;
+
+ using iterator_adaptor_base::operator++;
+ call_iterator &operator++() {
+ ++I;
+ advanceToNextEdge();
+ return *this;
+ }
+ };
+
+ iterator begin() { return iterator(Edges.begin(), Edges.end()); }
+ iterator end() { return iterator(Edges.end(), Edges.end()); }
+
+ Edge &operator[](int i) { return Edges[i]; }
+ Edge &operator[](Node &N) {
+ assert(EdgeIndexMap.find(&N) != EdgeIndexMap.end() && "No such edge!");
+ auto &E = Edges[EdgeIndexMap.find(&N)->second];
+ assert(E && "Dead or null edge!");
+ return E;
+ }
+
+ Edge *lookup(Node &N) {
+ auto EI = EdgeIndexMap.find(&N);
+ if (EI == EdgeIndexMap.end())
+ return nullptr;
+ auto &E = Edges[EI->second];
+ return E ? &E : nullptr;
+ }
+
+ call_iterator call_begin() {
+ return call_iterator(Edges.begin(), Edges.end());
+ }
+ call_iterator call_end() { return call_iterator(Edges.end(), Edges.end()); }
+
+ iterator_range<call_iterator> calls() {
+ return make_range(call_begin(), call_end());
+ }
+
+ bool empty() {
+ for (auto &E : Edges)
+ if (E)
+ return false;
+
+ return true;
+ }
+
+ private:
+ VectorT Edges;
+ DenseMap<Node *, int> EdgeIndexMap;
+
+ EdgeSequence() = default;
+
+ /// Internal helper to insert an edge to a node.
+ void insertEdgeInternal(Node &ChildN, Edge::Kind EK);
+
+ /// Internal helper to change an edge kind.
+ void setEdgeKind(Node &ChildN, Edge::Kind EK);
+
+ /// Internal helper to remove the edge to the given function.
+ bool removeEdgeInternal(Node &ChildN);
+
+ /// Internal helper to replace an edge key with a new one.
+ ///
+ /// This should be used when the function for a particular node in the
+ /// graph gets replaced and we are updating all of the edges to that node
+ /// to use the new function as the key.
+ void replaceEdgeKey(Function &OldTarget, Function &NewTarget);
+ };
+
+ /// A node in the call graph.
+ ///
+ /// This represents a single node. It's primary roles are to cache the list of
+ /// callees, de-duplicate and provide fast testing of whether a function is
+ /// a callee, and facilitate iteration of child nodes in the graph.
+ ///
+ /// The node works much like an optional in order to lazily populate the
+ /// edges of each node. Until populated, there are no edges. Once populated,
+ /// you can access the edges by dereferencing the node or using the `->`
+ /// operator as if the node was an `Optional<EdgeSequence>`.
+ class Node {
+ friend class LazyCallGraph;
+ friend class LazyCallGraph::RefSCC;
+
+ public:
+ LazyCallGraph &getGraph() const { return *G; }
+
+ Function &getFunction() const { return *F; }
+
+ StringRef getName() const { return F->getName(); }
+
+ /// Equality is defined as address equality.
+ bool operator==(const Node &N) const { return this == &N; }
+ bool operator!=(const Node &N) const { return !operator==(N); }
+
+ /// Tests whether the node has been populated with edges.
+ bool isPopulated() const { return Edges.hasValue(); }
+
+ /// Tests whether this is actually a dead node and no longer valid.
+ ///
+ /// Users rarely interact with nodes in this state and other methods are
+ /// invalid. This is used to model a node in an edge list where the
+ /// function has been completely removed.
+ bool isDead() const {
+ assert(!G == !F &&
+ "Both graph and function pointers should be null or non-null.");
+ return !G;
+ }
+
+ // We allow accessing the edges by dereferencing or using the arrow
+ // operator, essentially wrapping the internal optional.
+ EdgeSequence &operator*() const {
+ // Rip const off because the node itself isn't changing here.
+ return const_cast<EdgeSequence &>(*Edges);
+ }
+ EdgeSequence *operator->() const { return &**this; }
+
+ /// Populate the edges of this node if necessary.
+ ///
+ /// The first time this is called it will populate the edges for this node
+ /// in the graph. It does this by scanning the underlying function, so once
+ /// this is done, any changes to that function must be explicitly reflected
+ /// in updates to the graph.
+ ///
+ /// \returns the populated \c EdgeSequence to simplify walking it.
+ ///
+ /// This will not update or re-scan anything if called repeatedly. Instead,
+ /// the edge sequence is cached and returned immediately on subsequent
+ /// calls.
+ EdgeSequence &populate() {
+ if (Edges)
+ return *Edges;
+
+ return populateSlow();
+ }
+
+ private:
+ LazyCallGraph *G;
+ Function *F;
+
+ // We provide for the DFS numbering and Tarjan walk lowlink numbers to be
+ // stored directly within the node. These are both '-1' when nodes are part
+ // of an SCC (or RefSCC), or '0' when not yet reached in a DFS walk.
+ int DFSNumber = 0;
+ int LowLink = 0;
+
+ Optional<EdgeSequence> Edges;
+
+ /// Basic constructor implements the scanning of F into Edges and
+ /// EdgeIndexMap.
+ Node(LazyCallGraph &G, Function &F) : G(&G), F(&F) {}
+
+ /// Implementation of the scan when populating.
+ EdgeSequence &populateSlow();
+
+ /// Internal helper to directly replace the function with a new one.
+ ///
+ /// This is used to facilitate tranfsormations which need to replace the
+ /// formal Function object but directly move the body and users from one to
+ /// the other.
+ void replaceFunction(Function &NewF);
+
+ void clear() { Edges.reset(); }
+
+ /// Print the name of this node's function.
+ friend raw_ostream &operator<<(raw_ostream &OS, const Node &N) {
+ return OS << N.F->getName();
+ }
+
+ /// Dump the name of this node's function to stderr.
+ void dump() const;
+ };
+
+ /// An SCC of the call graph.
+ ///
+ /// This represents a Strongly Connected Component of the direct call graph
+ /// -- ignoring indirect calls and function references. It stores this as
+ /// a collection of call graph nodes. While the order of nodes in the SCC is
+ /// stable, it is not any particular order.
+ ///
+ /// The SCCs are nested within a \c RefSCC, see below for details about that
+ /// outer structure. SCCs do not support mutation of the call graph, that
+ /// must be done through the containing \c RefSCC in order to fully reason
+ /// about the ordering and connections of the graph.
+ class SCC {
+ friend class LazyCallGraph;
+ friend class LazyCallGraph::Node;
+
+ RefSCC *OuterRefSCC;
+ SmallVector<Node *, 1> Nodes;
+
+ template <typename NodeRangeT>
+ SCC(RefSCC &OuterRefSCC, NodeRangeT &&Nodes)
+ : OuterRefSCC(&OuterRefSCC), Nodes(std::forward<NodeRangeT>(Nodes)) {}
+
+ void clear() {
+ OuterRefSCC = nullptr;
+ Nodes.clear();
+ }
+
+ /// Print a short descrtiption useful for debugging or logging.
+ ///
+ /// We print the function names in the SCC wrapped in '()'s and skipping
+ /// the middle functions if there are a large number.
+ //
+ // Note: this is defined inline to dodge issues with GCC's interpretation
+ // of enclosing namespaces for friend function declarations.
+ friend raw_ostream &operator<<(raw_ostream &OS, const SCC &C) {
+ OS << '(';
+ int i = 0;
+ for (LazyCallGraph::Node &N : C) {
+ if (i > 0)
+ OS << ", ";
+ // Elide the inner elements if there are too many.
+ if (i > 8) {
+ OS << "..., " << *C.Nodes.back();
+ break;
+ }
+ OS << N;
+ ++i;
+ }
+ OS << ')';
+ return OS;
+ }
+
+ /// Dump a short description of this SCC to stderr.
+ void dump() const;
+
+#ifndef NDEBUG
+ /// Verify invariants about the SCC.
+ ///
+ /// This will attempt to validate all of the basic invariants within an
+ /// SCC, but not that it is a strongly connected componet per-se. Primarily
+ /// useful while building and updating the graph to check that basic
+ /// properties are in place rather than having inexplicable crashes later.
+ void verify();
+#endif
+
+ public:
+ using iterator = pointee_iterator<SmallVectorImpl<Node *>::const_iterator>;
+
+ iterator begin() const { return Nodes.begin(); }
+ iterator end() const { return Nodes.end(); }
+
+ int size() const { return Nodes.size(); }
+
+ RefSCC &getOuterRefSCC() const { return *OuterRefSCC; }
+
+ /// Test if this SCC is a parent of \a C.
+ ///
+ /// Note that this is linear in the number of edges departing the current
+ /// SCC.
+ bool isParentOf(const SCC &C) const;
+
+ /// Test if this SCC is an ancestor of \a C.
+ ///
+ /// Note that in the worst case this is linear in the number of edges
+ /// departing the current SCC and every SCC in the entire graph reachable
+ /// from this SCC. Thus this very well may walk every edge in the entire
+ /// call graph! Do not call this in a tight loop!
+ bool isAncestorOf(const SCC &C) const;
+
+ /// Test if this SCC is a child of \a C.
+ ///
+ /// See the comments for \c isParentOf for detailed notes about the
+ /// complexity of this routine.
+ bool isChildOf(const SCC &C) const { return C.isParentOf(*this); }
+
+ /// Test if this SCC is a descendant of \a C.
+ ///
+ /// See the comments for \c isParentOf for detailed notes about the
+ /// complexity of this routine.
+ bool isDescendantOf(const SCC &C) const { return C.isAncestorOf(*this); }
+
+ /// Provide a short name by printing this SCC to a std::string.
+ ///
+ /// This copes with the fact that we don't have a name per-se for an SCC
+ /// while still making the use of this in debugging and logging useful.
+ std::string getName() const {
+ std::string Name;
+ raw_string_ostream OS(Name);
+ OS << *this;
+ OS.flush();
+ return Name;
+ }
+ };
+
+ /// A RefSCC of the call graph.
+ ///
+ /// This models a Strongly Connected Component of function reference edges in
+ /// the call graph. As opposed to actual SCCs, these can be used to scope
+ /// subgraphs of the module which are independent from other subgraphs of the
+ /// module because they do not reference it in any way. This is also the unit
+ /// where we do mutation of the graph in order to restrict mutations to those
+ /// which don't violate this independence.
+ ///
+ /// A RefSCC contains a DAG of actual SCCs. All the nodes within the RefSCC
+ /// are necessarily within some actual SCC that nests within it. Since
+ /// a direct call *is* a reference, there will always be at least one RefSCC
+ /// around any SCC.
+ class RefSCC {
+ friend class LazyCallGraph;
+ friend class LazyCallGraph::Node;
+
+ LazyCallGraph *G;
+
+ /// A postorder list of the inner SCCs.
+ SmallVector<SCC *, 4> SCCs;
+
+ /// A map from SCC to index in the postorder list.
+ SmallDenseMap<SCC *, int, 4> SCCIndices;
+
+ /// Fast-path constructor. RefSCCs should instead be constructed by calling
+ /// formRefSCCFast on the graph itself.
+ RefSCC(LazyCallGraph &G);
+
+ void clear() {
+ SCCs.clear();
+ SCCIndices.clear();
+ }
+
+ /// Print a short description useful for debugging or logging.
+ ///
+ /// We print the SCCs wrapped in '[]'s and skipping the middle SCCs if
+ /// there are a large number.
+ //
+ // Note: this is defined inline to dodge issues with GCC's interpretation
+ // of enclosing namespaces for friend function declarations.
+ friend raw_ostream &operator<<(raw_ostream &OS, const RefSCC &RC) {
+ OS << '[';
+ int i = 0;
+ for (LazyCallGraph::SCC &C : RC) {
+ if (i > 0)
+ OS << ", ";
+ // Elide the inner elements if there are too many.
+ if (i > 4) {
+ OS << "..., " << *RC.SCCs.back();
+ break;
+ }
+ OS << C;
+ ++i;
+ }
+ OS << ']';
+ return OS;
+ }
+
+ /// Dump a short description of this RefSCC to stderr.
+ void dump() const;
+
+#ifndef NDEBUG
+ /// Verify invariants about the RefSCC and all its SCCs.
+ ///
+ /// This will attempt to validate all of the invariants *within* the
+ /// RefSCC, but not that it is a strongly connected component of the larger
+ /// graph. This makes it useful even when partially through an update.
+ ///
+ /// Invariants checked:
+ /// - SCCs and their indices match.
+ /// - The SCCs list is in fact in post-order.
+ void verify();
+#endif
+
+ /// Handle any necessary parent set updates after inserting a trivial ref
+ /// or call edge.
+ void handleTrivialEdgeInsertion(Node &SourceN, Node &TargetN);
+
+ public:
+ using iterator = pointee_iterator<SmallVectorImpl<SCC *>::const_iterator>;
+ using range = iterator_range<iterator>;
+ using parent_iterator =
+ pointee_iterator<SmallPtrSetImpl<RefSCC *>::const_iterator>;
+
+ iterator begin() const { return SCCs.begin(); }
+ iterator end() const { return SCCs.end(); }
+
+ ssize_t size() const { return SCCs.size(); }
+
+ SCC &operator[](int Idx) { return *SCCs[Idx]; }
+
+ iterator find(SCC &C) const {
+ return SCCs.begin() + SCCIndices.find(&C)->second;
+ }
+
+ /// Test if this RefSCC is a parent of \a RC.
+ ///
+ /// CAUTION: This method walks every edge in the \c RefSCC, it can be very
+ /// expensive.
+ bool isParentOf(const RefSCC &RC) const;
+
+ /// Test if this RefSCC is an ancestor of \a RC.
+ ///
+ /// CAUTION: This method walks the directed graph of edges as far as
+ /// necessary to find a possible path to the argument. In the worst case
+ /// this may walk the entire graph and can be extremely expensive.
+ bool isAncestorOf(const RefSCC &RC) const;
+
+ /// Test if this RefSCC is a child of \a RC.
+ ///
+ /// CAUTION: This method walks every edge in the argument \c RefSCC, it can
+ /// be very expensive.
+ bool isChildOf(const RefSCC &RC) const { return RC.isParentOf(*this); }
+
+ /// Test if this RefSCC is a descendant of \a RC.
+ ///
+ /// CAUTION: This method walks the directed graph of edges as far as
+ /// necessary to find a possible path from the argument. In the worst case
+ /// this may walk the entire graph and can be extremely expensive.
+ bool isDescendantOf(const RefSCC &RC) const {
+ return RC.isAncestorOf(*this);
+ }
+
+ /// Provide a short name by printing this RefSCC to a std::string.
+ ///
+ /// This copes with the fact that we don't have a name per-se for an RefSCC
+ /// while still making the use of this in debugging and logging useful.
+ std::string getName() const {
+ std::string Name;
+ raw_string_ostream OS(Name);
+ OS << *this;
+ OS.flush();
+ return Name;
+ }
+
+ ///@{
+ /// \name Mutation API
+ ///
+ /// These methods provide the core API for updating the call graph in the
+ /// presence of (potentially still in-flight) DFS-found RefSCCs and SCCs.
+ ///
+ /// Note that these methods sometimes have complex runtimes, so be careful
+ /// how you call them.
+
+ /// Make an existing internal ref edge into a call edge.
+ ///
+ /// This may form a larger cycle and thus collapse SCCs into TargetN's SCC.
+ /// If that happens, the optional callback \p MergedCB will be invoked (if
+ /// provided) on the SCCs being merged away prior to actually performing
+ /// the merge. Note that this will never include the target SCC as that
+ /// will be the SCC functions are merged into to resolve the cycle. Once
+ /// this function returns, these merged SCCs are not in a valid state but
+ /// the pointers will remain valid until destruction of the parent graph
+ /// instance for the purpose of clearing cached information. This function
+ /// also returns 'true' if a cycle was formed and some SCCs merged away as
+ /// a convenience.
+ ///
+ /// After this operation, both SourceN's SCC and TargetN's SCC may move
+ /// position within this RefSCC's postorder list. Any SCCs merged are
+ /// merged into the TargetN's SCC in order to preserve reachability analyses
+ /// which took place on that SCC.
+ bool switchInternalEdgeToCall(
+ Node &SourceN, Node &TargetN,
+ function_ref<void(ArrayRef<SCC *> MergedSCCs)> MergeCB = {});
+
+ /// Make an existing internal call edge between separate SCCs into a ref
+ /// edge.
+ ///
+ /// If SourceN and TargetN in separate SCCs within this RefSCC, changing
+ /// the call edge between them to a ref edge is a trivial operation that
+ /// does not require any structural changes to the call graph.
+ void switchTrivialInternalEdgeToRef(Node &SourceN, Node &TargetN);
+
+ /// Make an existing internal call edge within a single SCC into a ref
+ /// edge.
+ ///
+ /// Since SourceN and TargetN are part of a single SCC, this SCC may be
+ /// split up due to breaking a cycle in the call edges that formed it. If
+ /// that happens, then this routine will insert new SCCs into the postorder
+ /// list *before* the SCC of TargetN (previously the SCC of both). This
+ /// preserves postorder as the TargetN can reach all of the other nodes by
+ /// definition of previously being in a single SCC formed by the cycle from
+ /// SourceN to TargetN.
+ ///
+ /// The newly added SCCs are added *immediately* and contiguously
+ /// prior to the TargetN SCC and return the range covering the new SCCs in
+ /// the RefSCC's postorder sequence. You can directly iterate the returned
+ /// range to observe all of the new SCCs in postorder.
+ ///
+ /// Note that if SourceN and TargetN are in separate SCCs, the simpler
+ /// routine `switchTrivialInternalEdgeToRef` should be used instead.
+ iterator_range<iterator> switchInternalEdgeToRef(Node &SourceN,
+ Node &TargetN);
+
+ /// Make an existing outgoing ref edge into a call edge.
+ ///
+ /// Note that this is trivial as there are no cyclic impacts and there
+ /// remains a reference edge.
+ void switchOutgoingEdgeToCall(Node &SourceN, Node &TargetN);
+
+ /// Make an existing outgoing call edge into a ref edge.
+ ///
+ /// This is trivial as there are no cyclic impacts and there remains
+ /// a reference edge.
+ void switchOutgoingEdgeToRef(Node &SourceN, Node &TargetN);
+
+ /// Insert a ref edge from one node in this RefSCC to another in this
+ /// RefSCC.
+ ///
+ /// This is always a trivial operation as it doesn't change any part of the
+ /// graph structure besides connecting the two nodes.
+ ///
+ /// Note that we don't support directly inserting internal *call* edges
+ /// because that could change the graph structure and requires returning
+ /// information about what became invalid. As a consequence, the pattern
+ /// should be to first insert the necessary ref edge, and then to switch it
+ /// to a call edge if needed and handle any invalidation that results. See
+ /// the \c switchInternalEdgeToCall routine for details.
+ void insertInternalRefEdge(Node &SourceN, Node &TargetN);
+
+ /// Insert an edge whose parent is in this RefSCC and child is in some
+ /// child RefSCC.
+ ///
+ /// There must be an existing path from the \p SourceN to the \p TargetN.
+ /// This operation is inexpensive and does not change the set of SCCs and
+ /// RefSCCs in the graph.
+ void insertOutgoingEdge(Node &SourceN, Node &TargetN, Edge::Kind EK);
+
+ /// Insert an edge whose source is in a descendant RefSCC and target is in
+ /// this RefSCC.
+ ///
+ /// There must be an existing path from the target to the source in this
+ /// case.
+ ///
+ /// NB! This is has the potential to be a very expensive function. It
+ /// inherently forms a cycle in the prior RefSCC DAG and we have to merge
+ /// RefSCCs to resolve that cycle. But finding all of the RefSCCs which
+ /// participate in the cycle can in the worst case require traversing every
+ /// RefSCC in the graph. Every attempt is made to avoid that, but passes
+ /// must still exercise caution calling this routine repeatedly.
+ ///
+ /// Also note that this can only insert ref edges. In order to insert
+ /// a call edge, first insert a ref edge and then switch it to a call edge.
+ /// These are intentionally kept as separate interfaces because each step
+ /// of the operation invalidates a different set of data structures.
+ ///
+ /// This returns all the RefSCCs which were merged into the this RefSCC
+ /// (the target's). This allows callers to invalidate any cached
+ /// information.
+ ///
+ /// FIXME: We could possibly optimize this quite a bit for cases where the
+ /// caller and callee are very nearby in the graph. See comments in the
+ /// implementation for details, but that use case might impact users.
+ SmallVector<RefSCC *, 1> insertIncomingRefEdge(Node &SourceN,
+ Node &TargetN);
+
+ /// Remove an edge whose source is in this RefSCC and target is *not*.
+ ///
+ /// This removes an inter-RefSCC edge. All inter-RefSCC edges originating
+ /// from this SCC have been fully explored by any in-flight DFS graph
+ /// formation, so this is always safe to call once you have the source
+ /// RefSCC.
+ ///
+ /// This operation does not change the cyclic structure of the graph and so
+ /// is very inexpensive. It may change the connectivity graph of the SCCs
+ /// though, so be careful calling this while iterating over them.
+ void removeOutgoingEdge(Node &SourceN, Node &TargetN);
+
+ /// Remove a list of ref edges which are entirely within this RefSCC.
+ ///
+ /// Both the \a SourceN and all of the \a TargetNs must be within this
+ /// RefSCC. Removing these edges may break cycles that form this RefSCC and
+ /// thus this operation may change the RefSCC graph significantly. In
+ /// particular, this operation will re-form new RefSCCs based on the
+ /// remaining connectivity of the graph. The following invariants are
+ /// guaranteed to hold after calling this method:
+ ///
+ /// 1) If a ref-cycle remains after removal, it leaves this RefSCC intact
+ /// and in the graph. No new RefSCCs are built.
+ /// 2) Otherwise, this RefSCC will be dead after this call and no longer in
+ /// the graph or the postorder traversal of the call graph. Any iterator
+ /// pointing at this RefSCC will become invalid.
+ /// 3) All newly formed RefSCCs will be returned and the order of the
+ /// RefSCCs returned will be a valid postorder traversal of the new
+ /// RefSCCs.
+ /// 4) No RefSCC other than this RefSCC has its member set changed (this is
+ /// inherent in the definition of removing such an edge).
+ ///
+ /// These invariants are very important to ensure that we can build
+ /// optimization pipelines on top of the CGSCC pass manager which
+ /// intelligently update the RefSCC graph without invalidating other parts
+ /// of the RefSCC graph.
+ ///
+ /// Note that we provide no routine to remove a *call* edge. Instead, you
+ /// must first switch it to a ref edge using \c switchInternalEdgeToRef.
+ /// This split API is intentional as each of these two steps can invalidate
+ /// a different aspect of the graph structure and needs to have the
+ /// invalidation handled independently.
+ ///
+ /// The runtime complexity of this method is, in the worst case, O(V+E)
+ /// where V is the number of nodes in this RefSCC and E is the number of
+ /// edges leaving the nodes in this RefSCC. Note that E includes both edges
+ /// within this RefSCC and edges from this RefSCC to child RefSCCs. Some
+ /// effort has been made to minimize the overhead of common cases such as
+ /// self-edges and edge removals which result in a spanning tree with no
+ /// more cycles.
+ SmallVector<RefSCC *, 1> removeInternalRefEdge(Node &SourceN,
+ ArrayRef<Node *> TargetNs);
+
+ /// A convenience wrapper around the above to handle trivial cases of
+ /// inserting a new call edge.
+ ///
+ /// This is trivial whenever the target is in the same SCC as the source or
+ /// the edge is an outgoing edge to some descendant SCC. In these cases
+ /// there is no change to the cyclic structure of SCCs or RefSCCs.
+ ///
+ /// To further make calling this convenient, it also handles inserting
+ /// already existing edges.
+ void insertTrivialCallEdge(Node &SourceN, Node &TargetN);
+
+ /// A convenience wrapper around the above to handle trivial cases of
+ /// inserting a new ref edge.
+ ///
+ /// This is trivial whenever the target is in the same RefSCC as the source
+ /// or the edge is an outgoing edge to some descendant RefSCC. In these
+ /// cases there is no change to the cyclic structure of the RefSCCs.
+ ///
+ /// To further make calling this convenient, it also handles inserting
+ /// already existing edges.
+ void insertTrivialRefEdge(Node &SourceN, Node &TargetN);
+
+ /// Directly replace a node's function with a new function.
+ ///
+ /// This should be used when moving the body and users of a function to
+ /// a new formal function object but not otherwise changing the call graph
+ /// structure in any way.
+ ///
+ /// It requires that the old function in the provided node have zero uses
+ /// and the new function must have calls and references to it establishing
+ /// an equivalent graph.
+ void replaceNodeFunction(Node &N, Function &NewF);
+
+ ///@}
+ };
+
+ /// A post-order depth-first RefSCC iterator over the call graph.
+ ///
+ /// This iterator walks the cached post-order sequence of RefSCCs. However,
+ /// it trades stability for flexibility. It is restricted to a forward
+ /// iterator but will survive mutations which insert new RefSCCs and continue
+ /// to point to the same RefSCC even if it moves in the post-order sequence.
+ class postorder_ref_scc_iterator
+ : public iterator_facade_base<postorder_ref_scc_iterator,
+ std::forward_iterator_tag, RefSCC> {
+ friend class LazyCallGraph;
+ friend class LazyCallGraph::Node;
+
+ /// Nonce type to select the constructor for the end iterator.
+ struct IsAtEndT {};
+
+ LazyCallGraph *G;
+ RefSCC *RC = nullptr;
+
+ /// Build the begin iterator for a node.
+ postorder_ref_scc_iterator(LazyCallGraph &G) : G(&G), RC(getRC(G, 0)) {}
+
+ /// Build the end iterator for a node. This is selected purely by overload.
+ postorder_ref_scc_iterator(LazyCallGraph &G, IsAtEndT /*Nonce*/) : G(&G) {}
+
+ /// Get the post-order RefSCC at the given index of the postorder walk,
+ /// populating it if necessary.
+ static RefSCC *getRC(LazyCallGraph &G, int Index) {
+ if (Index == (int)G.PostOrderRefSCCs.size())
+ // We're at the end.
+ return nullptr;
+
+ return G.PostOrderRefSCCs[Index];
+ }
+
+ public:
+ bool operator==(const postorder_ref_scc_iterator &Arg) const {
+ return G == Arg.G && RC == Arg.RC;
+ }
+
+ reference operator*() const { return *RC; }
+
+ using iterator_facade_base::operator++;
+ postorder_ref_scc_iterator &operator++() {
+ assert(RC && "Cannot increment the end iterator!");
+ RC = getRC(*G, G->RefSCCIndices.find(RC)->second + 1);
+ return *this;
+ }
+ };
+
+ /// Construct a graph for the given module.
+ ///
+ /// This sets up the graph and computes all of the entry points of the graph.
+ /// No function definitions are scanned until their nodes in the graph are
+ /// requested during traversal.
+ LazyCallGraph(Module &M, TargetLibraryInfo &TLI);
+
+ LazyCallGraph(LazyCallGraph &&G);
+ LazyCallGraph &operator=(LazyCallGraph &&RHS);
+
+ EdgeSequence::iterator begin() { return EntryEdges.begin(); }
+ EdgeSequence::iterator end() { return EntryEdges.end(); }
+
+ void buildRefSCCs();
+
+ postorder_ref_scc_iterator postorder_ref_scc_begin() {
+ if (!EntryEdges.empty())
+ assert(!PostOrderRefSCCs.empty() &&
+ "Must form RefSCCs before iterating them!");
+ return postorder_ref_scc_iterator(*this);
+ }
+ postorder_ref_scc_iterator postorder_ref_scc_end() {
+ if (!EntryEdges.empty())
+ assert(!PostOrderRefSCCs.empty() &&
+ "Must form RefSCCs before iterating them!");
+ return postorder_ref_scc_iterator(*this,
+ postorder_ref_scc_iterator::IsAtEndT());
+ }
+
+ iterator_range<postorder_ref_scc_iterator> postorder_ref_sccs() {
+ return make_range(postorder_ref_scc_begin(), postorder_ref_scc_end());
+ }
+
+ /// Lookup a function in the graph which has already been scanned and added.
+ Node *lookup(const Function &F) const { return NodeMap.lookup(&F); }
+
+ /// Lookup a function's SCC in the graph.
+ ///
+ /// \returns null if the function hasn't been assigned an SCC via the RefSCC
+ /// iterator walk.
+ SCC *lookupSCC(Node &N) const { return SCCMap.lookup(&N); }
+
+ /// Lookup a function's RefSCC in the graph.
+ ///
+ /// \returns null if the function hasn't been assigned a RefSCC via the
+ /// RefSCC iterator walk.
+ RefSCC *lookupRefSCC(Node &N) const {
+ if (SCC *C = lookupSCC(N))
+ return &C->getOuterRefSCC();
+
+ return nullptr;
+ }
+
+ /// Get a graph node for a given function, scanning it to populate the graph
+ /// data as necessary.
+ Node &get(Function &F) {
+ Node *&N = NodeMap[&F];
+ if (N)
+ return *N;
+
+ return insertInto(F, N);
+ }
+
+ /// Get the sequence of known and defined library functions.
+ ///
+ /// These functions, because they are known to LLVM, can have calls
+ /// introduced out of thin air from arbitrary IR.
+ ArrayRef<Function *> getLibFunctions() const {
+ return LibFunctions.getArrayRef();
+ }
+
+ /// Test whether a function is a known and defined library function tracked by
+ /// the call graph.
+ ///
+ /// Because these functions are known to LLVM they are specially modeled in
+ /// the call graph and even when all IR-level references have been removed
+ /// remain active and reachable.
+ bool isLibFunction(Function &F) const { return LibFunctions.count(&F); }
+
+ ///@{
+ /// \name Pre-SCC Mutation API
+ ///
+ /// These methods are only valid to call prior to forming any SCCs for this
+ /// call graph. They can be used to update the core node-graph during
+ /// a node-based inorder traversal that precedes any SCC-based traversal.
+ ///
+ /// Once you begin manipulating a call graph's SCCs, most mutation of the
+ /// graph must be performed via a RefSCC method. There are some exceptions
+ /// below.
+
+ /// Update the call graph after inserting a new edge.
+ void insertEdge(Node &SourceN, Node &TargetN, Edge::Kind EK);
+
+ /// Update the call graph after inserting a new edge.
+ void insertEdge(Function &Source, Function &Target, Edge::Kind EK) {
+ return insertEdge(get(Source), get(Target), EK);
+ }
+
+ /// Update the call graph after deleting an edge.
+ void removeEdge(Node &SourceN, Node &TargetN);
+
+ /// Update the call graph after deleting an edge.
+ void removeEdge(Function &Source, Function &Target) {
+ return removeEdge(get(Source), get(Target));
+ }
+
+ ///@}
+
+ ///@{
+ /// \name General Mutation API
+ ///
+ /// There are a very limited set of mutations allowed on the graph as a whole
+ /// once SCCs have started to be formed. These routines have strict contracts
+ /// but may be called at any point.
+
+ /// Remove a dead function from the call graph (typically to delete it).
+ ///
+ /// Note that the function must have an empty use list, and the call graph
+ /// must be up-to-date prior to calling this. That means it is by itself in
+ /// a maximal SCC which is by itself in a maximal RefSCC, etc. No structural
+ /// changes result from calling this routine other than potentially removing
+ /// entry points into the call graph.
+ ///
+ /// If SCC formation has begun, this function must not be part of the current
+ /// DFS in order to call this safely. Typically, the function will have been
+ /// fully visited by the DFS prior to calling this routine.
+ void removeDeadFunction(Function &F);
+
+ ///@}
+
+ ///@{
+ /// \name Static helpers for code doing updates to the call graph.
+ ///
+ /// These helpers are used to implement parts of the call graph but are also
+ /// useful to code doing updates or otherwise wanting to walk the IR in the
+ /// same patterns as when we build the call graph.
+
+ /// Recursively visits the defined functions whose address is reachable from
+ /// every constant in the \p Worklist.
+ ///
+ /// Doesn't recurse through any constants already in the \p Visited set, and
+ /// updates that set with every constant visited.
+ ///
+ /// For each defined function, calls \p Callback with that function.
+ template <typename CallbackT>
+ static void visitReferences(SmallVectorImpl<Constant *> &Worklist,
+ SmallPtrSetImpl<Constant *> &Visited,
+ CallbackT Callback) {
+ while (!Worklist.empty()) {
+ Constant *C = Worklist.pop_back_val();
+
+ if (Function *F = dyn_cast<Function>(C)) {
+ if (!F->isDeclaration())
+ Callback(*F);
+ continue;
+ }
+
+ if (BlockAddress *BA = dyn_cast<BlockAddress>(C)) {
+ // The blockaddress constant expression is a weird special case, we
+ // can't generically walk its operands the way we do for all other
+ // constants.
+ if (Visited.insert(BA->getFunction()).second)
+ Worklist.push_back(BA->getFunction());
+ continue;
+ }
+
+ for (Value *Op : C->operand_values())
+ if (Visited.insert(cast<Constant>(Op)).second)
+ Worklist.push_back(cast<Constant>(Op));
+ }
+ }
+
+ ///@}
+
+private:
+ using node_stack_iterator = SmallVectorImpl<Node *>::reverse_iterator;
+ using node_stack_range = iterator_range<node_stack_iterator>;
+
+ /// Allocator that holds all the call graph nodes.
+ SpecificBumpPtrAllocator<Node> BPA;
+
+ /// Maps function->node for fast lookup.
+ DenseMap<const Function *, Node *> NodeMap;
+
+ /// The entry edges into the graph.
+ ///
+ /// These edges are from "external" sources. Put another way, they
+ /// escape at the module scope.
+ EdgeSequence EntryEdges;
+
+ /// Allocator that holds all the call graph SCCs.
+ SpecificBumpPtrAllocator<SCC> SCCBPA;
+
+ /// Maps Function -> SCC for fast lookup.
+ DenseMap<Node *, SCC *> SCCMap;
+
+ /// Allocator that holds all the call graph RefSCCs.
+ SpecificBumpPtrAllocator<RefSCC> RefSCCBPA;
+
+ /// The post-order sequence of RefSCCs.
+ ///
+ /// This list is lazily formed the first time we walk the graph.
+ SmallVector<RefSCC *, 16> PostOrderRefSCCs;
+
+ /// A map from RefSCC to the index for it in the postorder sequence of
+ /// RefSCCs.
+ DenseMap<RefSCC *, int> RefSCCIndices;
+
+ /// Defined functions that are also known library functions which the
+ /// optimizer can reason about and therefore might introduce calls to out of
+ /// thin air.
+ SmallSetVector<Function *, 4> LibFunctions;
+
+ /// Helper to insert a new function, with an already looked-up entry in
+ /// the NodeMap.
+ Node &insertInto(Function &F, Node *&MappedN);
+
+ /// Helper to update pointers back to the graph object during moves.
+ void updateGraphPtrs();
+
+ /// Allocates an SCC and constructs it using the graph allocator.
+ ///
+ /// The arguments are forwarded to the constructor.
+ template <typename... Ts> SCC *createSCC(Ts &&... Args) {
+ return new (SCCBPA.Allocate()) SCC(std::forward<Ts>(Args)...);
+ }
+
+ /// Allocates a RefSCC and constructs it using the graph allocator.
+ ///
+ /// The arguments are forwarded to the constructor.
+ template <typename... Ts> RefSCC *createRefSCC(Ts &&... Args) {
+ return new (RefSCCBPA.Allocate()) RefSCC(std::forward<Ts>(Args)...);
+ }
+
+ /// Common logic for building SCCs from a sequence of roots.
+ ///
+ /// This is a very generic implementation of the depth-first walk and SCC
+ /// formation algorithm. It uses a generic sequence of roots and generic
+ /// callbacks for each step. This is designed to be used to implement both
+ /// the RefSCC formation and SCC formation with shared logic.
+ ///
+ /// Currently this is a relatively naive implementation of Tarjan's DFS
+ /// algorithm to form the SCCs.
+ ///
+ /// FIXME: We should consider newer variants such as Nuutila.
+ template <typename RootsT, typename GetBeginT, typename GetEndT,
+ typename GetNodeT, typename FormSCCCallbackT>
+ static void buildGenericSCCs(RootsT &&Roots, GetBeginT &&GetBegin,
+ GetEndT &&GetEnd, GetNodeT &&GetNode,
+ FormSCCCallbackT &&FormSCC);
+
+ /// Build the SCCs for a RefSCC out of a list of nodes.
+ void buildSCCs(RefSCC &RC, node_stack_range Nodes);
+
+ /// Get the index of a RefSCC within the postorder traversal.
+ ///
+ /// Requires that this RefSCC is a valid one in the (perhaps partial)
+ /// postorder traversed part of the graph.
+ int getRefSCCIndex(RefSCC &RC) {
+ auto IndexIt = RefSCCIndices.find(&RC);
+ assert(IndexIt != RefSCCIndices.end() && "RefSCC doesn't have an index!");
+ assert(PostOrderRefSCCs[IndexIt->second] == &RC &&
+ "Index does not point back at RC!");
+ return IndexIt->second;
+ }
+};
+
+inline LazyCallGraph::Edge::Edge() : Value() {}
+inline LazyCallGraph::Edge::Edge(Node &N, Kind K) : Value(&N, K) {}
+
+inline LazyCallGraph::Edge::operator bool() const {
+ return Value.getPointer() && !Value.getPointer()->isDead();
+}
+
+inline LazyCallGraph::Edge::Kind LazyCallGraph::Edge::getKind() const {
+ assert(*this && "Queried a null edge!");
+ return Value.getInt();
+}
+
+inline bool LazyCallGraph::Edge::isCall() const {
+ assert(*this && "Queried a null edge!");
+ return getKind() == Call;
+}
+
+inline LazyCallGraph::Node &LazyCallGraph::Edge::getNode() const {
+ assert(*this && "Queried a null edge!");
+ return *Value.getPointer();
+}
+
+inline Function &LazyCallGraph::Edge::getFunction() const {
+ assert(*this && "Queried a null edge!");
+ return getNode().getFunction();
+}
+
+// Provide GraphTraits specializations for call graphs.
+template <> struct GraphTraits<LazyCallGraph::Node *> {
+ using NodeRef = LazyCallGraph::Node *;
+ using ChildIteratorType = LazyCallGraph::EdgeSequence::iterator;
+
+ static NodeRef getEntryNode(NodeRef N) { return N; }
+ static ChildIteratorType child_begin(NodeRef N) { return (*N)->begin(); }
+ static ChildIteratorType child_end(NodeRef N) { return (*N)->end(); }
+};
+template <> struct GraphTraits<LazyCallGraph *> {
+ using NodeRef = LazyCallGraph::Node *;
+ using ChildIteratorType = LazyCallGraph::EdgeSequence::iterator;
+
+ static NodeRef getEntryNode(NodeRef N) { return N; }
+ static ChildIteratorType child_begin(NodeRef N) { return (*N)->begin(); }
+ static ChildIteratorType child_end(NodeRef N) { return (*N)->end(); }
+};
+
+/// An analysis pass which computes the call graph for a module.
+class LazyCallGraphAnalysis : public AnalysisInfoMixin<LazyCallGraphAnalysis> {
+ friend AnalysisInfoMixin<LazyCallGraphAnalysis>;
+
+ static AnalysisKey Key;
+
+public:
+ /// Inform generic clients of the result type.
+ using Result = LazyCallGraph;
+
+ /// Compute the \c LazyCallGraph for the module \c M.
+ ///
+ /// This just builds the set of entry points to the call graph. The rest is
+ /// built lazily as it is walked.
+ LazyCallGraph run(Module &M, ModuleAnalysisManager &AM) {
+ return LazyCallGraph(M, AM.getResult<TargetLibraryAnalysis>(M));
+ }
+};
+
+/// A pass which prints the call graph to a \c raw_ostream.
+///
+/// This is primarily useful for testing the analysis.
+class LazyCallGraphPrinterPass
+ : public PassInfoMixin<LazyCallGraphPrinterPass> {
+ raw_ostream &OS;
+
+public:
+ explicit LazyCallGraphPrinterPass(raw_ostream &OS);
+
+ PreservedAnalyses run(Module &M, ModuleAnalysisManager &AM);
+};
+
+/// A pass which prints the call graph as a DOT file to a \c raw_ostream.
+///
+/// This is primarily useful for visualization purposes.
+class LazyCallGraphDOTPrinterPass
+ : public PassInfoMixin<LazyCallGraphDOTPrinterPass> {
+ raw_ostream &OS;
+
+public:
+ explicit LazyCallGraphDOTPrinterPass(raw_ostream &OS);
+
+ PreservedAnalyses run(Module &M, ModuleAnalysisManager &AM);
+};
+
+} // end namespace llvm
+
+#endif // LLVM_ANALYSIS_LAZYCALLGRAPH_H