[LCG] Switch the Callee sets to be DenseMaps pointing to the index into

the Callee list. This is going to be quite important to prevent removal
from going quadratic. No functionality changed at this point, this is
one of the refactoring patches I've broken out of my initial work toward
mutation updates of the call graph.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206938 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 13 insertions, 11 deletions

diff --git a/include/llvm/Analysis/LazyCallGraph.h b/include/llvm/Analysis/LazyCallGraph.h
index 66d3d50585..60f4955ae9 100644
--- a/include/llvm/Analysis/LazyCallGraph.h
+++ b/include/llvm/Analysis/LazyCallGraph.h
@@ -187,10 +187,10 @@ public:
     int LowLink;
 
     mutable NodeVectorT Callees;
-    SmallPtrSet<Function *, 4> CalleeSet;
+    DenseMap<Function *, size_t> CalleeIndexMap;
 
     /// \brief Basic constructor implements the scanning of F into Callees and
-    /// CalleeSet.
+    /// CalleeIndexMap.
     Node(LazyCallGraph &G, Function &F);
 
   public:
@@ -333,8 +333,9 @@ private:
   /// escape at the module scope.
   NodeVectorT EntryNodes;
 
-  /// \brief Set of the entry nodes to the graph.
-  SmallPtrSet<Function *, 4> EntryNodeSet;
+  /// \brief Map of the entry nodes in the graph to their indices in
+  /// \c EntryNodes.
+  DenseMap<Function *, size_t> EntryIndexMap;
 
   /// \brief Allocator that holds all the call graph SCCs.
   SpecificBumpPtrAllocator<SCC> SCCBPA;
diff --git a/lib/Analysis/LazyCallGraph.cpp b/lib/Analysis/LazyCallGraph.cpp
index 8ae1840fce..201e644da9 100644
--- a/lib/Analysis/LazyCallGraph.cpp
+++ b/lib/Analysis/LazyCallGraph.cpp
@@ -23,7 +23,7 @@ using namespace llvm;
 static void findCallees(
     SmallVectorImpl<Constant *> &Worklist, SmallPtrSetImpl<Constant *> &Visited,
     SmallVectorImpl<PointerUnion<Function *, LazyCallGraph::Node *>> &Callees,
-    SmallPtrSetImpl<Function *> &CalleeSet) {
+    DenseMap<Function *, size_t> &CalleeIndexMap) {
   while (!Worklist.empty()) {
     Constant *C = Worklist.pop_back_val();
 
@@ -38,7 +38,8 @@ static void findCallees(
       // alias. Then a test of the address of the weak function against the new
       // strong definition's address would be an effective way to determine the
       // safety of optimizing a direct call edge.
-      if (!F->isDeclaration() && CalleeSet.insert(F)) {
+      if (!F->isDeclaration() &&
+          CalleeIndexMap.insert(std::make_pair(F, Callees.size())).second) {
         DEBUG(dbgs() << "    Added callable function: " << F->getName()
                      << "\n");
         Callees.push_back(F);
@@ -71,7 +72,7 @@ LazyCallGraph::Node::Node(LazyCallGraph &G, Function &F)
   // We've collected all the constant (and thus potentially function or
   // function containing) operands to all of the instructions in the function.
   // Process them (recursively) collecting every function found.
-  findCallees(Worklist, Visited, Callees, CalleeSet);
+  findCallees(Worklist, Visited, Callees, CalleeIndexMap);
 }
 
 LazyCallGraph::LazyCallGraph(Module &M) : NextDFSNumber(0) {
@@ -79,7 +80,7 @@ LazyCallGraph::LazyCallGraph(Module &M) : NextDFSNumber(0) {
                << "\n");
   for (Function &F : M)
     if (!F.isDeclaration() && !F.hasLocalLinkage())
-      if (EntryNodeSet.insert(&F)) {
+      if (EntryIndexMap.insert(std::make_pair(&F, EntryNodes.size())).second) {
         DEBUG(dbgs() << "  Adding '" << F.getName()
                      << "' to entry set of the graph.\n");
         EntryNodes.push_back(&F);
@@ -95,7 +96,7 @@ LazyCallGraph::LazyCallGraph(Module &M) : NextDFSNumber(0) {
 
   DEBUG(dbgs() << "  Adding functions referenced by global initializers to the "
                   "entry set.\n");
-  findCallees(Worklist, Visited, EntryNodes, EntryNodeSet);
+  findCallees(Worklist, Visited, EntryNodes, EntryIndexMap);
 
   for (auto &Entry : EntryNodes)
     if (Function *F = Entry.dyn_cast<Function *>())
@@ -107,7 +108,7 @@ LazyCallGraph::LazyCallGraph(Module &M) : NextDFSNumber(0) {
 LazyCallGraph::LazyCallGraph(LazyCallGraph &&G)
     : BPA(std::move(G.BPA)), NodeMap(std::move(G.NodeMap)),
       EntryNodes(std::move(G.EntryNodes)),
-      EntryNodeSet(std::move(G.EntryNodeSet)), SCCBPA(std::move(G.SCCBPA)),
+      EntryIndexMap(std::move(G.EntryIndexMap)), SCCBPA(std::move(G.SCCBPA)),
       SCCMap(std::move(G.SCCMap)), LeafSCCs(std::move(G.LeafSCCs)),
       DFSStack(std::move(G.DFSStack)),
       SCCEntryNodes(std::move(G.SCCEntryNodes)),
@@ -119,7 +120,7 @@ LazyCallGraph &LazyCallGraph::operator=(LazyCallGraph &&G) {
   BPA = std::move(G.BPA);
   NodeMap = std::move(G.NodeMap);
   EntryNodes = std::move(G.EntryNodes);
-  EntryNodeSet = std::move(G.EntryNodeSet);
+  EntryIndexMap = std::move(G.EntryIndexMap);
   SCCBPA = std::move(G.SCCBPA);
   SCCMap = std::move(G.SCCMap);
   LeafSCCs = std::move(G.LeafSCCs);