[LCG] Just move the allocator (now that we can) when moving a call

graph. This simplifies the custom move constructor operation to one of
walking the graph and updating the 'up' pointers to point to the new
location of the graph. Switch the nodes from a reference to a pointer
for the 'up' edge to facilitate this.

llvm-svn: 206450

1 files changed, 14 insertions, 28 deletions

diff --git a/llvm/lib/Analysis/LazyCallGraph.cpp b/llvm/lib/Analysis/LazyCallGraph.cpp
index 17d7d89..8a0d00a 100644
--- a/llvm/lib/Analysis/LazyCallGraph.cpp
+++ b/llvm/lib/Analysis/LazyCallGraph.cpp
@@ -46,7 +46,7 @@ static void findCallees(
   }
 }
 
-LazyCallGraph::Node::Node(LazyCallGraph &G, Function &F) : G(G), F(F) {
+LazyCallGraph::Node::Node(LazyCallGraph &G, Function &F) : G(&G), F(F) {
   SmallVector<Constant *, 16> Worklist;
   SmallPtrSet<Constant *, 16> Visited;
   // Find all the potential callees in this function. First walk the
@@ -65,7 +65,7 @@ LazyCallGraph::Node::Node(LazyCallGraph &G, Function &F) : G(G), F(F) {
 }
 
 LazyCallGraph::Node::Node(LazyCallGraph &G, const Node &OtherN)
-    : G(G), F(OtherN.F), CalleeSet(OtherN.CalleeSet) {
+    : G(&G), F(OtherN.F), CalleeSet(OtherN.CalleeSet) {
   // Loop over the other node's callees, adding the Function*s to our list
   // directly, and recursing to add the Node*s.
   Callees.reserve(OtherN.Callees.size());
@@ -76,16 +76,6 @@ LazyCallGraph::Node::Node(LazyCallGraph &G, const Node &OtherN)
       Callees.push_back(G.copyInto(*OtherCallee.get<Node *>()));
 }
 
-LazyCallGraph::Node::Node(LazyCallGraph &G, Node &&OtherN)
-    : G(G), F(OtherN.F), Callees(std::move(OtherN.Callees)),
-      CalleeSet(std::move(OtherN.CalleeSet)) {
-  // Loop over our Callees. They've been moved from another node, but we need
-  // to move the Node*s to live under our bump ptr allocator.
-  for (auto &Callee : Callees)
-    if (Node *ChildN = Callee.dyn_cast<Node *>())
-      Callee = G.moveInto(std::move(*ChildN));
-}
-
 LazyCallGraph::LazyCallGraph(Module &M) {
   for (Function &F : M)
     if (!F.isDeclaration() && !F.hasLocalLinkage())
@@ -113,18 +103,22 @@ LazyCallGraph::LazyCallGraph(const LazyCallGraph &G)
       EntryNodes.push_back(copyInto(*EntryNode.get<Node *>()));
 }
 
-// FIXME: This would be crazy simpler if BumpPtrAllocator were movable without
-// invalidating any of the allocated memory. We should make that be the case at
-// some point and delete this.
 LazyCallGraph::LazyCallGraph(LazyCallGraph &&G)
-    : EntryNodes(std::move(G.EntryNodes)),
+    : BPA(std::move(G.BPA)), EntryNodes(std::move(G.EntryNodes)),
       EntryNodeSet(std::move(G.EntryNodeSet)) {
-  // Loop over our EntryNodes. They've been moved from another graph, so we
-  // need to move the Node*s to live under our bump ptr allocator. We can just
-  // do this in-place.
+  // Process all nodes updating the graph pointers.
+  SmallVector<Node *, 16> Worklist;
   for (auto &Entry : EntryNodes)
     if (Node *EntryN = Entry.dyn_cast<Node *>())
-      Entry = moveInto(std::move(*EntryN));
+      Worklist.push_back(EntryN);
+
+  while (!Worklist.empty()) {
+    Node *N = Worklist.pop_back_val();
+    N->G = this;
+    for (auto &Callee : N->Callees)
+      if (Node *CalleeN = Callee.dyn_cast<Node *>())
+        Worklist.push_back(CalleeN);
+  }
 }
 
 LazyCallGraph::Node *LazyCallGraph::insertInto(Function &F, Node *&MappedN) {
@@ -139,14 +133,6 @@ LazyCallGraph::Node *LazyCallGraph::copyInto(const Node &OtherN) {
   return new (N = BPA.Allocate()) Node(*this, OtherN);
 }
 
-LazyCallGraph::Node *LazyCallGraph::moveInto(Node &&OtherN) {
-  Node *&N = NodeMap[&OtherN.F];
-  if (N)
-    return N;
-
-  return new (N = BPA.Allocate()) Node(*this, std::move(OtherN));
-}
-
 char LazyCallGraphAnalysis::PassID;
 
 LazyCallGraphPrinterPass::LazyCallGraphPrinterPass(raw_ostream &OS) : OS(OS) {}