///
//===----------------------------------------------------------------------===//
-#ifndef LLVM_ANALYSIS_LAZY_CALL_GRAPH
-#define LLVM_ANALYSIS_LAZY_CALL_GRAPH
+#ifndef LLVM_ANALYSIS_LAZYCALLGRAPH_H
+#define LLVM_ANALYSIS_LAZYCALLGRAPH_H
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/PointerUnion.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/Module.h"
+#include "llvm/IR/PassManager.h"
#include "llvm/Support/Allocator.h"
#include <iterator>
namespace llvm {
-class ModuleAnalysisManager;
class PreservedAnalyses;
class raw_ostream;
/// be scanned for "calls" or uses of functions and its child information
/// will be constructed. All of these results are accumulated and cached in
/// the graph.
- class iterator : public iterator_adaptor_base<
- iterator, NodeVectorImplT::iterator, Node> {
+ class iterator
+ : public iterator_adaptor_base<iterator, NodeVectorImplT::iterator,
+ std::forward_iterator_tag, Node> {
friend class LazyCallGraph;
friend class LazyCallGraph::Node;
LazyCallGraph *G;
- NodeVectorImplT::iterator NI;
+ NodeVectorImplT::iterator E;
// Build the iterator for a specific position in a node list.
- iterator(LazyCallGraph &G, NodeVectorImplT::iterator NI)
- : iterator_adaptor_base(NI), G(&G) {}
+ iterator(LazyCallGraph &G, NodeVectorImplT::iterator NI,
+ NodeVectorImplT::iterator E)
+ : iterator_adaptor_base(NI), G(&G), E(E) {
+ while (I != E && I->isNull())
+ ++I;
+ }
public:
iterator() {}
+ using iterator_adaptor_base::operator++;
+ iterator &operator++() {
+ do {
+ ++I;
+ } while (I != E && I->isNull());
+ return *this;
+ }
+
reference operator*() const {
if (I->is<Node *>())
return *I->get<Node *>();
/// CalleeIndexMap.
Node(LazyCallGraph &G, Function &F);
+ /// \brief Internal helper to insert a callee.
+ void insertEdgeInternal(Function &Callee);
+
+ /// \brief Internal helper to insert a callee.
+ void insertEdgeInternal(Node &CalleeN);
+
+ /// \brief Internal helper to remove a callee from this node.
+ void removeEdgeInternal(Function &Callee);
+
public:
typedef LazyCallGraph::iterator iterator;
return F;
};
- iterator begin() const { return iterator(*G, Callees.begin()); }
- iterator end() const { return iterator(*G, Callees.end()); }
+ iterator begin() const {
+ return iterator(*G, Callees.begin(), Callees.end());
+ }
+ iterator end() const { return iterator(*G, Callees.end(), Callees.end()); }
/// Equality is defined as address equality.
bool operator==(const Node &N) const { return this == &N; }
friend class LazyCallGraph;
friend class LazyCallGraph::Node;
+ LazyCallGraph *G;
SmallPtrSet<SCC *, 1> ParentSCCs;
SmallVector<Node *, 1> Nodes;
- SCC() {}
-
- void insert(LazyCallGraph &G, Node &N);
+ SCC(LazyCallGraph &G) : G(&G) {}
- void removeEdge(LazyCallGraph &G, Function &Caller, Function &Callee,
- SCC &CalleeC);
+ void insert(Node &N);
void
- internalDFS(LazyCallGraph &G,
- SmallVectorImpl<std::pair<Node *, Node::iterator>> &DFSStack,
+ internalDFS(SmallVectorImpl<std::pair<Node *, Node::iterator>> &DFSStack,
SmallVectorImpl<Node *> &PendingSCCStack, Node *N,
SmallVectorImpl<SCC *> &ResultSCCs);
- SmallVector<LazyCallGraph::SCC *, 1>
- removeInternalEdge(LazyCallGraph &G, Node &Caller, Node &Callee);
-
public:
typedef SmallVectorImpl<Node *>::const_iterator iterator;
typedef pointee_iterator<SmallPtrSet<SCC *, 1>::const_iterator> parent_iterator;
iterator_range<parent_iterator> parents() const {
return iterator_range<parent_iterator>(parent_begin(), parent_end());
}
+
+ /// \brief Test if this SCC is a parent of \a C.
+ bool isParentOf(const SCC &C) const { return C.isChildOf(*this); }
+
+ /// \brief Test if this SCC is an ancestor of \a C.
+ bool isAncestorOf(const SCC &C) const { return C.isDescendantOf(*this); }
+
+ /// \brief Test if this SCC is a child of \a C.
+ bool isChildOf(const SCC &C) const {
+ return ParentSCCs.count(const_cast<SCC *>(&C));
+ }
+
+ /// \brief Test if this SCC is a descendant of \a C.
+ bool isDescendantOf(const SCC &C) const;
+
+ /// \brief Short name useful for debugging or logging.
+ ///
+ /// We use the name of the first function in the SCC to name the SCC for
+ /// the purposes of debugging and logging.
+ StringRef getName() const { return (*begin())->getFunction().getName(); }
+
+ ///@{
+ /// \name Mutation API
+ ///
+ /// These methods provide the core API for updating the call graph in the
+ /// presence of a (potentially still in-flight) DFS-found SCCs.
+ ///
+ /// Note that these methods sometimes have complex runtimes, so be careful
+ /// how you call them.
+
+ /// \brief Insert an edge from one node in this SCC to another in this SCC.
+ ///
+ /// By the definition of an SCC, this does not change the nature or make-up
+ /// of any SCCs.
+ void insertIntraSCCEdge(Node &CallerN, Node &CalleeN);
+
+ /// \brief Insert an edge whose tail is in this SCC and head is in some
+ /// child SCC.
+ ///
+ /// There must be an existing path from the caller to the callee. This
+ /// operation is inexpensive and does not change the set of SCCs in the
+ /// graph.
+ void insertOutgoingEdge(Node &CallerN, Node &CalleeN);
+
+ /// \brief Insert an edge whose tail is in a descendant SCC and head is in
+ /// this SCC.
+ ///
+ /// There must be an existing path from the callee to the caller in this
+ /// case. NB! This is has the potential to be a very expensive function. It
+ /// inherently forms a cycle in the prior SCC DAG and we have to merge SCCs
+ /// to resolve that cycle. But finding all of the SCCs which participate in
+ /// the cycle can in the worst case require traversing every SCC in the
+ /// graph. Every attempt is made to avoid that, but passes must still
+ /// exercise caution calling this routine repeatedly.
+ ///
+ /// 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<SCC *, 1> insertIncomingEdge(Node &CallerN, Node &CalleeN);
+
+ /// \brief Remove an edge whose source is in this SCC and target is *not*.
+ ///
+ /// This removes an inter-SCC edge. All inter-SCC edges originating from
+ /// this SCC have been fully explored by any in-flight DFS SCC formation,
+ /// so this is always safe to call once you have the source SCC.
+ ///
+ /// This operation does not change the set of SCCs or the members of the
+ /// SCCs 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 removeInterSCCEdge(Node &CallerN, Node &CalleeN);
+
+ /// \brief Remove an edge which is entirely within this SCC.
+ ///
+ /// Both the \a Caller and the \a Callee must be within this SCC. Removing
+ /// such an edge make break cycles that form this SCC and thus this
+ /// operation may change the SCC graph significantly. In particular, this
+ /// operation will re-form new SCCs based on the remaining connectivity of
+ /// the graph. The following invariants are guaranteed to hold after
+ /// calling this method:
+ ///
+ /// 1) This SCC is still an SCC in the graph.
+ /// 2) This SCC will be the parent of any new SCCs. Thus, this SCC is
+ /// preserved as the root of any new SCC directed graph formed.
+ /// 3) No SCC other than this SCC has its member set changed (this is
+ /// inherent in the definition of removing such an edge).
+ /// 4) All of the parent links of the SCC graph will be updated to reflect
+ /// the new SCC structure.
+ /// 5) All SCCs formed out of this SCC, excluding this SCC, will be
+ /// returned in a vector.
+ /// 6) The order of the SCCs in the vector will be a valid postorder
+ /// traversal of the new SCCs.
+ ///
+ /// These invariants are very important to ensure that we can build
+ /// optimization pipeliens on top of the CGSCC pass manager which
+ /// intelligently update the SCC graph without invalidating other parts of
+ /// the SCC graph.
+ ///
+ /// The runtime complexity of this method is, in the worst case, O(V+E)
+ /// where V is the number of nodes in this SCC and E is the number of edges
+ /// leaving the nodes in this SCC. Note that E includes both edges within
+ /// this SCC and edges from this SCC to child SCCs. 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<SCC *, 1> removeIntraSCCEdge(Node &CallerN, Node &CalleeN);
+
+ ///@}
};
/// \brief A post-order depth-first SCC iterator over the call graph.
LazyCallGraph(LazyCallGraph &&G);
LazyCallGraph &operator=(LazyCallGraph &&RHS);
- iterator begin() { return iterator(*this, EntryNodes.begin()); }
- iterator end() { return iterator(*this, EntryNodes.end()); }
+ iterator begin() {
+ return iterator(*this, EntryNodes.begin(), EntryNodes.end());
+ }
+ iterator end() { return iterator(*this, EntryNodes.end(), EntryNodes.end()); }
postorder_scc_iterator postorder_scc_begin() {
return postorder_scc_iterator(*this);
return insertInto(F, N);
}
+ ///@{
+ /// \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, you must perform all
+ /// mutation of the graph via the SCC methods.
+
+ /// \brief Update the call graph after inserting a new edge.
+ void insertEdge(Node &Caller, Function &Callee);
+
+ /// \brief Update the call graph after inserting a new edge.
+ void insertEdge(Function &Caller, Function &Callee) {
+ return insertEdge(get(Caller), Callee);
+ }
+
/// \brief Update the call graph after deleting an edge.
void removeEdge(Node &Caller, Function &Callee);
return removeEdge(get(Caller), Callee);
}
+ ///@}
+
private:
/// \brief Allocator that holds all the call graph nodes.
SpecificBumpPtrAllocator<Node> BPA;
static void *ID() { return (void *)&PassID; }
- /// \brief Compute the \c LazyCallGraph for a the module \c M.
+ static StringRef name() { return "Lazy CallGraph Analysis"; }
+
+ /// \brief 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) { return LazyCallGraph(*M); }
+ LazyCallGraph run(Module &M) { return LazyCallGraph(M); }
private:
static char PassID;
public:
explicit LazyCallGraphPrinterPass(raw_ostream &OS);
- PreservedAnalyses run(Module *M, ModuleAnalysisManager *AM);
+ PreservedAnalyses run(Module &M, ModuleAnalysisManager *AM);
static StringRef name() { return "LazyCallGraphPrinterPass"; }
};