Re-land "Add LazyCallGraph API to add function to RefSCC"

This re-commits https://reviews.llvm.org/D70927, which I reverted in
https://reviews.llvm.org/rG28213680b2a7d1fdeea16aa3f3a368879472c72a due
to a buildbot error:
http://lab.llvm.org:8011/builders/clang-cmake-x86_64-avx2-linux/builds/13251

I no longer include a test case that appears to crash when built with the
buildbot's compiler, GCC 5.4.0.

1 files changed, 26 insertions, 6 deletions

diff --git a/llvm/lib/Analysis/LazyCallGraph.cpp b/llvm/lib/Analysis/LazyCallGraph.cpp
index cdf1d55..0d647cb 100644
--- a/llvm/lib/Analysis/LazyCallGraph.cpp
+++ b/llvm/lib/Analysis/LazyCallGraph.cpp
@@ -1567,12 +1567,17 @@ void LazyCallGraph::removeDeadFunction(Function &F) {
 }
 
 void LazyCallGraph::addNewFunctionIntoSCC(Function &NewF, SCC &C) {
-  Node &CGNode = get(NewF);
-  CGNode.DFSNumber = CGNode.LowLink = -1;
-  CGNode.populate();
-  C.Nodes.push_back(&CGNode);
-  SCCMap[&CGNode] = &C;
-  NodeMap[&NewF] = &CGNode;
+  addNodeToSCC(C, createNode(NewF));
+}
+
+void LazyCallGraph::addNewFunctionIntoRefSCC(Function &NewF, RefSCC &RC) {
+  Node &N = createNode(NewF);
+
+  auto *C = createSCC(RC, SmallVector<Node *, 1>());
+  addNodeToSCC(*C, N);
+
+  RC.SCCIndices[C] = RC.SCCIndices.size();
+  RC.SCCs.push_back(C);
 }
 
 LazyCallGraph::Node &LazyCallGraph::insertInto(Function &F, Node *&MappedN) {
@@ -1589,6 +1594,21 @@ void LazyCallGraph::updateGraphPtrs() {
     RC->G = this;
 }
 
+LazyCallGraph::Node &LazyCallGraph::createNode(Function &F) {
+  assert(!lookup(F) && "node already exists");
+
+  Node &N = get(F);
+  NodeMap[&F] = &N;
+  N.DFSNumber = N.LowLink = -1;
+  N.populate();
+  return N;
+}
+
+void LazyCallGraph::addNodeToSCC(LazyCallGraph::SCC &C, Node &N) {
+  C.Nodes.push_back(&N);
+  SCCMap[&N] = &C;
+}
+
 template <typename RootsT, typename GetBeginT, typename GetEndT,
           typename GetNodeT, typename FormSCCCallbackT>
 void LazyCallGraph::buildGenericSCCs(RootsT &&Roots, GetBeginT &&GetBegin,