X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=include%2Fllvm%2FAnalysis%2FLazyCallGraph.h;h=b0b9068de34bf7a2d90f39053ecc94fcd8ed22a3;hb=32439e7d8822d0d62b3954cc3afe91e5b826db8a;hp=6aa0b8e0a2f747b80c53e7cdc543bd8ff1700d19;hpb=306d5ba0923b6554c5c6e1c43cae9ae08341459d;p=oota-llvm.git

diff --git a/include/llvm/Analysis/LazyCallGraph.h b/include/llvm/Analysis/LazyCallGraph.h
index 6aa0b8e0a2f..b0b9068de34 100644
--- a/include/llvm/Analysis/LazyCallGraph.h
+++ b/include/llvm/Analysis/LazyCallGraph.h
@@ -32,8 +32,8 @@
 ///
 //===----------------------------------------------------------------------===//
 
-#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"
@@ -41,15 +41,16 @@
 #include "llvm/ADT/SetVector.h"
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/iterator.h"
 #include "llvm/ADT/iterator_range.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;
 
@@ -112,59 +113,42 @@ public:
   /// 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 std::iterator<std::bidirectional_iterator_tag, Node> {
+  class iterator
+      : public iterator_adaptor_base<iterator, NodeVectorImplT::iterator,
+                                     std::forward_iterator_tag, Node> {
     friend class LazyCallGraph;
     friend class LazyCallGraph::Node;
-    typedef std::iterator<std::bidirectional_iterator_tag, Node *, ptrdiff_t,
-                          Node *, Node *> BaseT;
-
-    /// \brief Nonce type to select the constructor for the end iterator.
-    struct IsAtEndT {};
 
     LazyCallGraph *G;
-    NodeVectorImplT::iterator NI;
-
-    // Build the begin iterator for a node.
-    explicit iterator(LazyCallGraph &G, NodeVectorImplT &Nodes)
-        : G(&G), NI(Nodes.begin()) {}
-
-    // Build the end iterator for a node. This is selected purely by overload.
-    iterator(LazyCallGraph &G, NodeVectorImplT &Nodes, IsAtEndT /*Nonce*/)
-        : G(&G), NI(Nodes.end()) {}
+    NodeVectorImplT::iterator E;
+
+    // Build the iterator for a specific position in a node list.
+    iterator(LazyCallGraph &G, NodeVectorImplT::iterator NI,
+             NodeVectorImplT::iterator E)
+        : iterator_adaptor_base(NI), G(&G), E(E) {
+      while (I != E && I->isNull())
+        ++I;
+    }
 
   public:
-    bool operator==(const iterator &Arg) const { return NI == Arg.NI; }
-    bool operator!=(const iterator &Arg) const { return !operator==(Arg); }
-
-    reference operator*() const {
-      if (NI->is<Node *>())
-        return *NI->get<Node *>();
-
-      Function *F = NI->get<Function *>();
-      Node &ChildN = G->get(*F);
-      *NI = &ChildN;
-      return ChildN;
-    }
-    pointer operator->() const { return &operator*(); }
+    iterator() {}
 
+    using iterator_adaptor_base::operator++;
     iterator &operator++() {
-      ++NI;
+      do {
+        ++I;
+      } while (I != E && I->isNull());
       return *this;
     }
-    iterator operator++(int) {
-      iterator prev = *this;
-      ++*this;
-      return prev;
-    }
 
-    iterator &operator--() {
-      --NI;
-      return *this;
-    }
-    iterator operator--(int) {
-      iterator next = *this;
-      --*this;
-      return next;
+    reference operator*() const {
+      if (I->is<Node *>())
+        return *I->get<Node *>();
+
+      Function *F = I->get<Function *>();
+      Node &ChildN = G->get(*F);
+      *I = &ChildN;
+      return ChildN;
     }
   };
 
@@ -192,6 +176,15 @@ public:
     /// 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;
 
@@ -199,8 +192,10 @@ public:
       return F;
     };
 
-    iterator begin() const { return iterator(*G, Callees); }
-    iterator end() const { return iterator(*G, Callees, iterator::IsAtEndT()); }
+    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; }
@@ -216,21 +211,22 @@ public:
     friend class LazyCallGraph;
     friend class LazyCallGraph::Node;
 
-    SmallSetVector<SCC *, 1> ParentSCCs;
+    LazyCallGraph *G;
+    SmallPtrSet<SCC *, 1> ParentSCCs;
     SmallVector<Node *, 1> Nodes;
-    SmallPtrSet<Function *, 1> NodeSet;
 
-    SCC() {}
+    SCC(LazyCallGraph &G) : G(&G) {}
 
-    void removeEdge(LazyCallGraph &G, Function &Caller, Function &Callee,
-                    SCC &CalleeC);
+    void insert(Node &N);
 
-    SmallVector<LazyCallGraph::SCC *, 1>
-    removeInternalEdge(LazyCallGraph &G, Node &Caller, Node &Callee);
+    void
+    internalDFS(SmallVectorImpl<std::pair<Node *, Node::iterator>> &DFSStack,
+                SmallVectorImpl<Node *> &PendingSCCStack, Node *N,
+                SmallVectorImpl<SCC *> &ResultSCCs);
 
   public:
     typedef SmallVectorImpl<Node *>::const_iterator iterator;
-    typedef SmallSetVector<SCC *, 1>::const_iterator parent_iterator;
+    typedef pointee_iterator<SmallPtrSet<SCC *, 1>::const_iterator> parent_iterator;
 
     iterator begin() const { return Nodes.begin(); }
     iterator end() const { return Nodes.end(); }
@@ -241,6 +237,113 @@ public:
     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.
@@ -250,12 +353,10 @@ public:
   /// always visits SCCs for a callee prior to visiting the SCC for a caller
   /// (when they are in different SCCs).
   class postorder_scc_iterator
-      : public std::iterator<std::forward_iterator_tag, SCC *, ptrdiff_t, SCC *,
-                             SCC *> {
+      : public iterator_facade_base<postorder_scc_iterator,
+                                    std::forward_iterator_tag, SCC> {
     friend class LazyCallGraph;
     friend class LazyCallGraph::Node;
-    typedef std::iterator<std::forward_iterator_tag, SCC *, ptrdiff_t,
-                          SCC *, SCC *> BaseT;
 
     /// \brief Nonce type to select the constructor for the end iterator.
     struct IsAtEndT {};
@@ -276,22 +377,14 @@ public:
     bool operator==(const postorder_scc_iterator &Arg) const {
       return G == Arg.G && C == Arg.C;
     }
-    bool operator!=(const postorder_scc_iterator &Arg) const {
-      return !operator==(Arg);
-    }
 
-    reference operator*() const { return C; }
-    pointer operator->() const { return operator*(); }
+    reference operator*() const { return *C; }
 
+    using iterator_facade_base::operator++;
     postorder_scc_iterator &operator++() {
       C = G->getNextSCCInPostOrder();
       return *this;
     }
-    postorder_scc_iterator operator++(int) {
-      postorder_scc_iterator prev = *this;
-      ++*this;
-      return prev;
-    }
   };
 
   /// \brief Construct a graph for the given module.
@@ -304,8 +397,10 @@ public:
   LazyCallGraph(LazyCallGraph &&G);
   LazyCallGraph &operator=(LazyCallGraph &&RHS);
 
-  iterator begin() { return iterator(*this, EntryNodes); }
-  iterator end() { return iterator(*this, EntryNodes, iterator::IsAtEndT()); }
+  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);
@@ -339,6 +434,24 @@ public:
     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);
 
@@ -347,6 +460,8 @@ public:
     return removeEdge(get(Caller), Callee);
   }
 
+  ///@}
+
 private:
   /// \brief Allocator that holds all the call graph nodes.
   SpecificBumpPtrAllocator<Node> BPA;
@@ -375,11 +490,14 @@ private:
   /// These are all of the SCCs which have no children.
   SmallVector<SCC *, 4> LeafSCCs;
 
-  /// \brief Stack of nodes not-yet-processed into SCCs.
+  /// \brief Stack of nodes in the DFS walk.
   SmallVector<std::pair<Node *, iterator>, 4> DFSStack;
 
   /// \brief Set of entry nodes not-yet-processed into SCCs.
-  SmallSetVector<Function *, 4> SCCEntryNodes;
+  SmallVector<Function *, 4> SCCEntryNodes;
+
+  /// \brief Stack of nodes the DFS has walked but not yet put into a SCC.
+  SmallVector<Node *, 4> PendingSCCStack;
 
   /// \brief Counter for the next DFS number to assign.
   int NextDFSNumber;
@@ -393,9 +511,7 @@ private:
 
   /// \brief Helper to form a new SCC out of the top of a DFSStack-like
   /// structure.
-  SCC *formSCCFromDFSStack(
-      SmallVectorImpl<std::pair<Node *, Node::iterator>> &DFSStack,
-      SmallVectorImpl<std::pair<Node *, Node::iterator>>::iterator SCCBegin);
+  SCC *formSCC(Node *RootN, SmallVectorImpl<Node *> &NodeStack);
 
   /// \brief Retrieve the next node in the post-order SCC walk of the call graph.
   SCC *getNextSCCInPostOrder();
@@ -427,11 +543,13 @@ public:
 
   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;
@@ -446,7 +564,7 @@ class LazyCallGraphPrinterPass {
 public:
   explicit LazyCallGraphPrinterPass(raw_ostream &OS);
 
-  PreservedAnalyses run(Module *M, ModuleAnalysisManager *AM);
+  PreservedAnalyses run(Module &M, ModuleAnalysisManager *AM);
 
   static StringRef name() { return "LazyCallGraphPrinterPass"; }
 };