Vendor import of llvm RELEASE_350/final tag r216957 (effectively, 3.5.0 release):

https://llvm.org/svn/llvm-project/llvm/tags/RELEASE_350/final@216957

1 files changed, 720 insertions, 0 deletions

diff --git a/unittests/Analysis/LazyCallGraphTest.cpp b/unittests/Analysis/LazyCallGraphTest.cpp
new file mode 100644
index 0000000..d7c7045
--- /dev/null
+++ b/unittests/Analysis/LazyCallGraphTest.cpp
@@ -0,0 +1,720 @@
+//===- LazyCallGraphTest.cpp - Unit tests for the lazy CG analysis --------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Analysis/LazyCallGraph.h"
+#include "llvm/AsmParser/Parser.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/Module.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/SourceMgr.h"
+#include "gtest/gtest.h"
+#include <memory>
+
+using namespace llvm;
+
+namespace {
+
+std::unique_ptr<Module> parseAssembly(const char *Assembly) {
+  auto M = make_unique<Module>("Module", getGlobalContext());
+
+  SMDiagnostic Error;
+  bool Parsed =
+      ParseAssemblyString(Assembly, M.get(), Error, M->getContext()) == M.get();
+
+  std::string ErrMsg;
+  raw_string_ostream OS(ErrMsg);
+  Error.print("", OS);
+
+  // A failure here means that the test itself is buggy.
+  if (!Parsed)
+    report_fatal_error(OS.str().c_str());
+
+  return M;
+}
+
+// IR forming a call graph with a diamond of triangle-shaped SCCs:
+//
+//         d1
+//        /  \
+//       d3--d2
+//      /     \
+//     b1     c1
+//   /  \    /  \
+//  b3--b2  c3--c2
+//       \  /
+//        a1
+//       /  \
+//      a3--a2
+//
+// All call edges go up between SCCs, and clockwise around the SCC.
+static const char DiamondOfTriangles[] =
+     "define void @a1() {\n"
+     "entry:\n"
+     "  call void @a2()\n"
+     "  call void @b2()\n"
+     "  call void @c3()\n"
+     "  ret void\n"
+     "}\n"
+     "define void @a2() {\n"
+     "entry:\n"
+     "  call void @a3()\n"
+     "  ret void\n"
+     "}\n"
+     "define void @a3() {\n"
+     "entry:\n"
+     "  call void @a1()\n"
+     "  ret void\n"
+     "}\n"
+     "define void @b1() {\n"
+     "entry:\n"
+     "  call void @b2()\n"
+     "  call void @d3()\n"
+     "  ret void\n"
+     "}\n"
+     "define void @b2() {\n"
+     "entry:\n"
+     "  call void @b3()\n"
+     "  ret void\n"
+     "}\n"
+     "define void @b3() {\n"
+     "entry:\n"
+     "  call void @b1()\n"
+     "  ret void\n"
+     "}\n"
+     "define void @c1() {\n"
+     "entry:\n"
+     "  call void @c2()\n"
+     "  call void @d2()\n"
+     "  ret void\n"
+     "}\n"
+     "define void @c2() {\n"
+     "entry:\n"
+     "  call void @c3()\n"
+     "  ret void\n"
+     "}\n"
+     "define void @c3() {\n"
+     "entry:\n"
+     "  call void @c1()\n"
+     "  ret void\n"
+     "}\n"
+     "define void @d1() {\n"
+     "entry:\n"
+     "  call void @d2()\n"
+     "  ret void\n"
+     "}\n"
+     "define void @d2() {\n"
+     "entry:\n"
+     "  call void @d3()\n"
+     "  ret void\n"
+     "}\n"
+     "define void @d3() {\n"
+     "entry:\n"
+     "  call void @d1()\n"
+     "  ret void\n"
+     "}\n";
+
+TEST(LazyCallGraphTest, BasicGraphFormation) {
+  std::unique_ptr<Module> M = parseAssembly(DiamondOfTriangles);
+  LazyCallGraph CG(*M);
+
+  // The order of the entry nodes should be stable w.r.t. the source order of
+  // the IR, and everything in our module is an entry node, so just directly
+  // build variables for each node.
+  auto I = CG.begin();
+  LazyCallGraph::Node &A1 = *I++;
+  EXPECT_EQ("a1", A1.getFunction().getName());
+  LazyCallGraph::Node &A2 = *I++;
+  EXPECT_EQ("a2", A2.getFunction().getName());
+  LazyCallGraph::Node &A3 = *I++;
+  EXPECT_EQ("a3", A3.getFunction().getName());
+  LazyCallGraph::Node &B1 = *I++;
+  EXPECT_EQ("b1", B1.getFunction().getName());
+  LazyCallGraph::Node &B2 = *I++;
+  EXPECT_EQ("b2", B2.getFunction().getName());
+  LazyCallGraph::Node &B3 = *I++;
+  EXPECT_EQ("b3", B3.getFunction().getName());
+  LazyCallGraph::Node &C1 = *I++;
+  EXPECT_EQ("c1", C1.getFunction().getName());
+  LazyCallGraph::Node &C2 = *I++;
+  EXPECT_EQ("c2", C2.getFunction().getName());
+  LazyCallGraph::Node &C3 = *I++;
+  EXPECT_EQ("c3", C3.getFunction().getName());
+  LazyCallGraph::Node &D1 = *I++;
+  EXPECT_EQ("d1", D1.getFunction().getName());
+  LazyCallGraph::Node &D2 = *I++;
+  EXPECT_EQ("d2", D2.getFunction().getName());
+  LazyCallGraph::Node &D3 = *I++;
+  EXPECT_EQ("d3", D3.getFunction().getName());
+  EXPECT_EQ(CG.end(), I);
+
+  // Build vectors and sort them for the rest of the assertions to make them
+  // independent of order.
+  std::vector<std::string> Nodes;
+
+  for (LazyCallGraph::Node &N : A1)
+    Nodes.push_back(N.getFunction().getName());
+  std::sort(Nodes.begin(), Nodes.end());
+  EXPECT_EQ("a2", Nodes[0]);
+  EXPECT_EQ("b2", Nodes[1]);
+  EXPECT_EQ("c3", Nodes[2]);
+  Nodes.clear();
+
+  EXPECT_EQ(A2.end(), std::next(A2.begin()));
+  EXPECT_EQ("a3", A2.begin()->getFunction().getName());
+  EXPECT_EQ(A3.end(), std::next(A3.begin()));
+  EXPECT_EQ("a1", A3.begin()->getFunction().getName());
+
+  for (LazyCallGraph::Node &N : B1)
+    Nodes.push_back(N.getFunction().getName());
+  std::sort(Nodes.begin(), Nodes.end());
+  EXPECT_EQ("b2", Nodes[0]);
+  EXPECT_EQ("d3", Nodes[1]);
+  Nodes.clear();
+
+  EXPECT_EQ(B2.end(), std::next(B2.begin()));
+  EXPECT_EQ("b3", B2.begin()->getFunction().getName());
+  EXPECT_EQ(B3.end(), std::next(B3.begin()));
+  EXPECT_EQ("b1", B3.begin()->getFunction().getName());
+
+  for (LazyCallGraph::Node &N : C1)
+    Nodes.push_back(N.getFunction().getName());
+  std::sort(Nodes.begin(), Nodes.end());
+  EXPECT_EQ("c2", Nodes[0]);
+  EXPECT_EQ("d2", Nodes[1]);
+  Nodes.clear();
+
+  EXPECT_EQ(C2.end(), std::next(C2.begin()));
+  EXPECT_EQ("c3", C2.begin()->getFunction().getName());
+  EXPECT_EQ(C3.end(), std::next(C3.begin()));
+  EXPECT_EQ("c1", C3.begin()->getFunction().getName());
+
+  EXPECT_EQ(D1.end(), std::next(D1.begin()));
+  EXPECT_EQ("d2", D1.begin()->getFunction().getName());
+  EXPECT_EQ(D2.end(), std::next(D2.begin()));
+  EXPECT_EQ("d3", D2.begin()->getFunction().getName());
+  EXPECT_EQ(D3.end(), std::next(D3.begin()));
+  EXPECT_EQ("d1", D3.begin()->getFunction().getName());
+
+  // Now lets look at the SCCs.
+  auto SCCI = CG.postorder_scc_begin();
+
+  LazyCallGraph::SCC &D = *SCCI++;
+  for (LazyCallGraph::Node *N : D)
+    Nodes.push_back(N->getFunction().getName());
+  std::sort(Nodes.begin(), Nodes.end());
+  EXPECT_EQ(3u, Nodes.size());
+  EXPECT_EQ("d1", Nodes[0]);
+  EXPECT_EQ("d2", Nodes[1]);
+  EXPECT_EQ("d3", Nodes[2]);
+  Nodes.clear();
+  EXPECT_FALSE(D.isParentOf(D));
+  EXPECT_FALSE(D.isChildOf(D));
+  EXPECT_FALSE(D.isAncestorOf(D));
+  EXPECT_FALSE(D.isDescendantOf(D));
+
+  LazyCallGraph::SCC &C = *SCCI++;
+  for (LazyCallGraph::Node *N : C)
+    Nodes.push_back(N->getFunction().getName());
+  std::sort(Nodes.begin(), Nodes.end());
+  EXPECT_EQ(3u, Nodes.size());
+  EXPECT_EQ("c1", Nodes[0]);
+  EXPECT_EQ("c2", Nodes[1]);
+  EXPECT_EQ("c3", Nodes[2]);
+  Nodes.clear();
+  EXPECT_TRUE(C.isParentOf(D));
+  EXPECT_FALSE(C.isChildOf(D));
+  EXPECT_TRUE(C.isAncestorOf(D));
+  EXPECT_FALSE(C.isDescendantOf(D));
+
+  LazyCallGraph::SCC &B = *SCCI++;
+  for (LazyCallGraph::Node *N : B)
+    Nodes.push_back(N->getFunction().getName());
+  std::sort(Nodes.begin(), Nodes.end());
+  EXPECT_EQ(3u, Nodes.size());
+  EXPECT_EQ("b1", Nodes[0]);
+  EXPECT_EQ("b2", Nodes[1]);
+  EXPECT_EQ("b3", Nodes[2]);
+  Nodes.clear();
+  EXPECT_TRUE(B.isParentOf(D));
+  EXPECT_FALSE(B.isChildOf(D));
+  EXPECT_TRUE(B.isAncestorOf(D));
+  EXPECT_FALSE(B.isDescendantOf(D));
+  EXPECT_FALSE(B.isAncestorOf(C));
+  EXPECT_FALSE(C.isAncestorOf(B));
+
+  LazyCallGraph::SCC &A = *SCCI++;
+  for (LazyCallGraph::Node *N : A)
+    Nodes.push_back(N->getFunction().getName());
+  std::sort(Nodes.begin(), Nodes.end());
+  EXPECT_EQ(3u, Nodes.size());
+  EXPECT_EQ("a1", Nodes[0]);
+  EXPECT_EQ("a2", Nodes[1]);
+  EXPECT_EQ("a3", Nodes[2]);
+  Nodes.clear();
+  EXPECT_TRUE(A.isParentOf(B));
+  EXPECT_TRUE(A.isParentOf(C));
+  EXPECT_FALSE(A.isParentOf(D));
+  EXPECT_TRUE(A.isAncestorOf(B));
+  EXPECT_TRUE(A.isAncestorOf(C));
+  EXPECT_TRUE(A.isAncestorOf(D));
+
+  EXPECT_EQ(CG.postorder_scc_end(), SCCI);
+}
+
+static Function &lookupFunction(Module &M, StringRef Name) {
+  for (Function &F : M)
+    if (F.getName() == Name)
+      return F;
+  report_fatal_error("Couldn't find function!");
+}
+
+TEST(LazyCallGraphTest, BasicGraphMutation) {
+  std::unique_ptr<Module> M = parseAssembly(
+      "define void @a() {\n"
+      "entry:\n"
+      "  call void @b()\n"
+      "  call void @c()\n"
+      "  ret void\n"
+      "}\n"
+      "define void @b() {\n"
+      "entry:\n"
+      "  ret void\n"
+      "}\n"
+      "define void @c() {\n"
+      "entry:\n"
+      "  ret void\n"
+      "}\n");
+  LazyCallGraph CG(*M);
+
+  LazyCallGraph::Node &A = CG.get(lookupFunction(*M, "a"));
+  LazyCallGraph::Node &B = CG.get(lookupFunction(*M, "b"));
+  EXPECT_EQ(2, std::distance(A.begin(), A.end()));
+  EXPECT_EQ(0, std::distance(B.begin(), B.end()));
+
+  CG.insertEdge(B, lookupFunction(*M, "c"));
+  EXPECT_EQ(1, std::distance(B.begin(), B.end()));
+  LazyCallGraph::Node &C = *B.begin();
+  EXPECT_EQ(0, std::distance(C.begin(), C.end()));
+
+  CG.insertEdge(C, B.getFunction());
+  EXPECT_EQ(1, std::distance(C.begin(), C.end()));
+  EXPECT_EQ(&B, &*C.begin());
+
+  CG.insertEdge(C, C.getFunction());
+  EXPECT_EQ(2, std::distance(C.begin(), C.end()));
+  EXPECT_EQ(&B, &*C.begin());
+  EXPECT_EQ(&C, &*std::next(C.begin()));
+
+  CG.removeEdge(C, B.getFunction());
+  EXPECT_EQ(1, std::distance(C.begin(), C.end()));
+  EXPECT_EQ(&C, &*C.begin());
+
+  CG.removeEdge(C, C.getFunction());
+  EXPECT_EQ(0, std::distance(C.begin(), C.end()));
+
+  CG.removeEdge(B, C.getFunction());
+  EXPECT_EQ(0, std::distance(B.begin(), B.end()));
+}
+
+TEST(LazyCallGraphTest, MultiArmSCC) {
+  // Two interlocking cycles. The really useful thing about this SCC is that it
+  // will require Tarjan's DFS to backtrack and finish processing all of the
+  // children of each node in the SCC.
+  std::unique_ptr<Module> M = parseAssembly(
+      "define void @a() {\n"
+      "entry:\n"
+      "  call void @b()\n"
+      "  call void @d()\n"
+      "  ret void\n"
+      "}\n"
+      "define void @b() {\n"
+      "entry:\n"
+      "  call void @c()\n"
+      "  ret void\n"
+      "}\n"
+      "define void @c() {\n"
+      "entry:\n"
+      "  call void @a()\n"
+      "  ret void\n"
+      "}\n"
+      "define void @d() {\n"
+      "entry:\n"
+      "  call void @e()\n"
+      "  ret void\n"
+      "}\n"
+      "define void @e() {\n"
+      "entry:\n"
+      "  call void @a()\n"
+      "  ret void\n"
+      "}\n");
+  LazyCallGraph CG(*M);
+
+  // Force the graph to be fully expanded.
+  auto SCCI = CG.postorder_scc_begin();
+  LazyCallGraph::SCC &SCC = *SCCI++;
+  EXPECT_EQ(CG.postorder_scc_end(), SCCI);
+
+  LazyCallGraph::Node &A = *CG.lookup(lookupFunction(*M, "a"));
+  LazyCallGraph::Node &B = *CG.lookup(lookupFunction(*M, "b"));
+  LazyCallGraph::Node &C = *CG.lookup(lookupFunction(*M, "c"));
+  LazyCallGraph::Node &D = *CG.lookup(lookupFunction(*M, "d"));
+  LazyCallGraph::Node &E = *CG.lookup(lookupFunction(*M, "e"));
+  EXPECT_EQ(&SCC, CG.lookupSCC(A));
+  EXPECT_EQ(&SCC, CG.lookupSCC(B));
+  EXPECT_EQ(&SCC, CG.lookupSCC(C));
+  EXPECT_EQ(&SCC, CG.lookupSCC(D));
+  EXPECT_EQ(&SCC, CG.lookupSCC(E));
+}
+
+TEST(LazyCallGraphTest, OutgoingSCCEdgeInsertion) {
+  std::unique_ptr<Module> M = parseAssembly(
+      "define void @a() {\n"
+      "entry:\n"
+      "  call void @b()\n"
+      "  call void @c()\n"
+      "  ret void\n"
+      "}\n"
+      "define void @b() {\n"
+      "entry:\n"
+      "  call void @d()\n"
+      "  ret void\n"
+      "}\n"
+      "define void @c() {\n"
+      "entry:\n"
+      "  call void @d()\n"
+      "  ret void\n"
+      "}\n"
+      "define void @d() {\n"
+      "entry:\n"
+      "  ret void\n"
+      "}\n");
+  LazyCallGraph CG(*M);
+
+  // Force the graph to be fully expanded.
+  for (LazyCallGraph::SCC &C : CG.postorder_sccs())
+    (void)C;
+
+  LazyCallGraph::Node &A = *CG.lookup(lookupFunction(*M, "a"));
+  LazyCallGraph::Node &B = *CG.lookup(lookupFunction(*M, "b"));
+  LazyCallGraph::Node &C = *CG.lookup(lookupFunction(*M, "c"));
+  LazyCallGraph::Node &D = *CG.lookup(lookupFunction(*M, "d"));
+  LazyCallGraph::SCC &AC = *CG.lookupSCC(A);
+  LazyCallGraph::SCC &BC = *CG.lookupSCC(B);
+  LazyCallGraph::SCC &CC = *CG.lookupSCC(C);
+  LazyCallGraph::SCC &DC = *CG.lookupSCC(D);
+  EXPECT_TRUE(AC.isAncestorOf(BC));
+  EXPECT_TRUE(AC.isAncestorOf(CC));
+  EXPECT_TRUE(AC.isAncestorOf(DC));
+  EXPECT_TRUE(DC.isDescendantOf(AC));
+  EXPECT_TRUE(DC.isDescendantOf(BC));
+  EXPECT_TRUE(DC.isDescendantOf(CC));
+
+  EXPECT_EQ(2, std::distance(A.begin(), A.end()));
+  AC.insertOutgoingEdge(A, D);
+  EXPECT_EQ(3, std::distance(A.begin(), A.end()));
+  EXPECT_TRUE(AC.isParentOf(DC));
+  EXPECT_EQ(&AC, CG.lookupSCC(A));
+  EXPECT_EQ(&BC, CG.lookupSCC(B));
+  EXPECT_EQ(&CC, CG.lookupSCC(C));
+  EXPECT_EQ(&DC, CG.lookupSCC(D));
+}
+
+TEST(LazyCallGraphTest, IncomingSCCEdgeInsertion) {
+  // We want to ensure we can add edges even across complex diamond graphs, so
+  // we use the diamond of triangles graph defined above. The ascii diagram is
+  // repeated here for easy reference.
+  //
+  //         d1       |
+  //        /  \      |
+  //       d3--d2     |
+  //      /     \     |
+  //     b1     c1    |
+  //   /  \    /  \   |
+  //  b3--b2  c3--c2  |
+  //       \  /       |
+  //        a1        |
+  //       /  \       |
+  //      a3--a2      |
+  //
+  std::unique_ptr<Module> M = parseAssembly(DiamondOfTriangles);
+  LazyCallGraph CG(*M);
+
+  // Force the graph to be fully expanded.
+  for (LazyCallGraph::SCC &C : CG.postorder_sccs())
+    (void)C;
+
+  LazyCallGraph::Node &A1 = *CG.lookup(lookupFunction(*M, "a1"));
+  LazyCallGraph::Node &A2 = *CG.lookup(lookupFunction(*M, "a2"));
+  LazyCallGraph::Node &A3 = *CG.lookup(lookupFunction(*M, "a3"));
+  LazyCallGraph::Node &B1 = *CG.lookup(lookupFunction(*M, "b1"));
+  LazyCallGraph::Node &B2 = *CG.lookup(lookupFunction(*M, "b2"));
+  LazyCallGraph::Node &B3 = *CG.lookup(lookupFunction(*M, "b3"));
+  LazyCallGraph::Node &C1 = *CG.lookup(lookupFunction(*M, "c1"));
+  LazyCallGraph::Node &C2 = *CG.lookup(lookupFunction(*M, "c2"));
+  LazyCallGraph::Node &C3 = *CG.lookup(lookupFunction(*M, "c3"));
+  LazyCallGraph::Node &D1 = *CG.lookup(lookupFunction(*M, "d1"));
+  LazyCallGraph::Node &D2 = *CG.lookup(lookupFunction(*M, "d2"));
+  LazyCallGraph::Node &D3 = *CG.lookup(lookupFunction(*M, "d3"));
+  LazyCallGraph::SCC &AC = *CG.lookupSCC(A1);
+  LazyCallGraph::SCC &BC = *CG.lookupSCC(B1);
+  LazyCallGraph::SCC &CC = *CG.lookupSCC(C1);
+  LazyCallGraph::SCC &DC = *CG.lookupSCC(D1);
+  ASSERT_EQ(&AC, CG.lookupSCC(A2));
+  ASSERT_EQ(&AC, CG.lookupSCC(A3));
+  ASSERT_EQ(&BC, CG.lookupSCC(B2));
+  ASSERT_EQ(&BC, CG.lookupSCC(B3));
+  ASSERT_EQ(&CC, CG.lookupSCC(C2));
+  ASSERT_EQ(&CC, CG.lookupSCC(C3));
+  ASSERT_EQ(&DC, CG.lookupSCC(D2));
+  ASSERT_EQ(&DC, CG.lookupSCC(D3));
+  ASSERT_EQ(1, std::distance(D2.begin(), D2.end()));
+
+  // Add an edge to make the graph:
+  //
+  //         d1         |
+  //        /  \        |
+  //       d3--d2---.   |
+  //      /     \    |  |
+  //     b1     c1   |  |
+  //   /  \    /  \ /   |
+  //  b3--b2  c3--c2    |
+  //       \  /         |
+  //        a1          |
+  //       /  \         |
+  //      a3--a2        |
+  CC.insertIncomingEdge(D2, C2);
+  // Make sure we connected the nodes.
+  EXPECT_EQ(2, std::distance(D2.begin(), D2.end()));
+
+  // Make sure we have the correct nodes in the SCC sets.
+  EXPECT_EQ(&AC, CG.lookupSCC(A1));
+  EXPECT_EQ(&AC, CG.lookupSCC(A2));
+  EXPECT_EQ(&AC, CG.lookupSCC(A3));
+  EXPECT_EQ(&BC, CG.lookupSCC(B1));
+  EXPECT_EQ(&BC, CG.lookupSCC(B2));
+  EXPECT_EQ(&BC, CG.lookupSCC(B3));
+  EXPECT_EQ(&CC, CG.lookupSCC(C1));
+  EXPECT_EQ(&CC, CG.lookupSCC(C2));
+  EXPECT_EQ(&CC, CG.lookupSCC(C3));
+  EXPECT_EQ(&CC, CG.lookupSCC(D1));
+  EXPECT_EQ(&CC, CG.lookupSCC(D2));
+  EXPECT_EQ(&CC, CG.lookupSCC(D3));
+
+  // And that ancestry tests have been updated.
+  EXPECT_TRUE(AC.isParentOf(BC));
+  EXPECT_TRUE(AC.isParentOf(CC));
+  EXPECT_FALSE(AC.isAncestorOf(DC));
+  EXPECT_FALSE(BC.isAncestorOf(DC));
+  EXPECT_FALSE(CC.isAncestorOf(DC));
+}
+
+TEST(LazyCallGraphTest, IncomingSCCEdgeInsertionMidTraversal) {
+  // This is the same fundamental test as the previous, but we perform it
+  // having only partially walked the SCCs of the graph.
+  std::unique_ptr<Module> M = parseAssembly(DiamondOfTriangles);
+  LazyCallGraph CG(*M);
+
+  // Walk the SCCs until we find the one containing 'c1'.
+  auto SCCI = CG.postorder_scc_begin(), SCCE = CG.postorder_scc_end();
+  ASSERT_NE(SCCI, SCCE);
+  LazyCallGraph::SCC &DC = *SCCI;
+  ASSERT_NE(&DC, nullptr);
+  ++SCCI;
+  ASSERT_NE(SCCI, SCCE);
+  LazyCallGraph::SCC &CC = *SCCI;
+  ASSERT_NE(&CC, nullptr);
+
+  ASSERT_EQ(nullptr, CG.lookup(lookupFunction(*M, "a1")));
+  ASSERT_EQ(nullptr, CG.lookup(lookupFunction(*M, "a2")));
+  ASSERT_EQ(nullptr, CG.lookup(lookupFunction(*M, "a3")));
+  ASSERT_EQ(nullptr, CG.lookup(lookupFunction(*M, "b1")));
+  ASSERT_EQ(nullptr, CG.lookup(lookupFunction(*M, "b2")));
+  ASSERT_EQ(nullptr, CG.lookup(lookupFunction(*M, "b3")));
+  LazyCallGraph::Node &C1 = *CG.lookup(lookupFunction(*M, "c1"));
+  LazyCallGraph::Node &C2 = *CG.lookup(lookupFunction(*M, "c2"));
+  LazyCallGraph::Node &C3 = *CG.lookup(lookupFunction(*M, "c3"));
+  LazyCallGraph::Node &D1 = *CG.lookup(lookupFunction(*M, "d1"));
+  LazyCallGraph::Node &D2 = *CG.lookup(lookupFunction(*M, "d2"));
+  LazyCallGraph::Node &D3 = *CG.lookup(lookupFunction(*M, "d3"));
+  ASSERT_EQ(&CC, CG.lookupSCC(C1));
+  ASSERT_EQ(&CC, CG.lookupSCC(C2));
+  ASSERT_EQ(&CC, CG.lookupSCC(C3));
+  ASSERT_EQ(&DC, CG.lookupSCC(D1));
+  ASSERT_EQ(&DC, CG.lookupSCC(D2));
+  ASSERT_EQ(&DC, CG.lookupSCC(D3));
+  ASSERT_EQ(1, std::distance(D2.begin(), D2.end()));
+
+  CC.insertIncomingEdge(D2, C2);
+  EXPECT_EQ(2, std::distance(D2.begin(), D2.end()));
+
+  // Make sure we have the correct nodes in the SCC sets.
+  EXPECT_EQ(&CC, CG.lookupSCC(C1));
+  EXPECT_EQ(&CC, CG.lookupSCC(C2));
+  EXPECT_EQ(&CC, CG.lookupSCC(C3));
+  EXPECT_EQ(&CC, CG.lookupSCC(D1));
+  EXPECT_EQ(&CC, CG.lookupSCC(D2));
+  EXPECT_EQ(&CC, CG.lookupSCC(D3));
+
+  // Check that we can form the last two SCCs now in a coherent way.
+  ++SCCI;
+  EXPECT_NE(SCCI, SCCE);
+  LazyCallGraph::SCC &BC = *SCCI;
+  EXPECT_NE(&BC, nullptr);
+  EXPECT_EQ(&BC, CG.lookupSCC(*CG.lookup(lookupFunction(*M, "b1"))));
+  EXPECT_EQ(&BC, CG.lookupSCC(*CG.lookup(lookupFunction(*M, "b2"))));
+  EXPECT_EQ(&BC, CG.lookupSCC(*CG.lookup(lookupFunction(*M, "b3"))));
+  ++SCCI;
+  EXPECT_NE(SCCI, SCCE);
+  LazyCallGraph::SCC &AC = *SCCI;
+  EXPECT_NE(&AC, nullptr);
+  EXPECT_EQ(&AC, CG.lookupSCC(*CG.lookup(lookupFunction(*M, "a1"))));
+  EXPECT_EQ(&AC, CG.lookupSCC(*CG.lookup(lookupFunction(*M, "a2"))));
+  EXPECT_EQ(&AC, CG.lookupSCC(*CG.lookup(lookupFunction(*M, "a3"))));
+  ++SCCI;
+  EXPECT_EQ(SCCI, SCCE);
+}
+
+TEST(LazyCallGraphTest, InterSCCEdgeRemoval) {
+  std::unique_ptr<Module> M = parseAssembly(
+      "define void @a() {\n"
+      "entry:\n"
+      "  call void @b()\n"
+      "  ret void\n"
+      "}\n"
+      "define void @b() {\n"
+      "entry:\n"
+      "  ret void\n"
+      "}\n");
+  LazyCallGraph CG(*M);
+
+  // Force the graph to be fully expanded.
+  for (LazyCallGraph::SCC &C : CG.postorder_sccs())
+    (void)C;
+
+  LazyCallGraph::Node &A = *CG.lookup(lookupFunction(*M, "a"));
+  LazyCallGraph::Node &B = *CG.lookup(lookupFunction(*M, "b"));
+  LazyCallGraph::SCC &AC = *CG.lookupSCC(A);
+  LazyCallGraph::SCC &BC = *CG.lookupSCC(B);
+
+  EXPECT_EQ("b", A.begin()->getFunction().getName());
+  EXPECT_EQ(B.end(), B.begin());
+  EXPECT_EQ(&AC, &*BC.parent_begin());
+
+  AC.removeInterSCCEdge(A, B);
+
+  EXPECT_EQ(A.end(), A.begin());
+  EXPECT_EQ(B.end(), B.begin());
+  EXPECT_EQ(BC.parent_end(), BC.parent_begin());
+}
+
+TEST(LazyCallGraphTest, IntraSCCEdgeInsertion) {
+  std::unique_ptr<Module> M1 = parseAssembly(
+      "define void @a() {\n"
+      "entry:\n"
+      "  call void @b()\n"
+      "  ret void\n"
+      "}\n"
+      "define void @b() {\n"
+      "entry:\n"
+      "  call void @c()\n"
+      "  ret void\n"
+      "}\n"
+      "define void @c() {\n"
+      "entry:\n"
+      "  call void @a()\n"
+      "  ret void\n"
+      "}\n");
+  LazyCallGraph CG1(*M1);
+
+  // Force the graph to be fully expanded.
+  auto SCCI = CG1.postorder_scc_begin();
+  LazyCallGraph::SCC &SCC = *SCCI++;
+  EXPECT_EQ(CG1.postorder_scc_end(), SCCI);
+
+  LazyCallGraph::Node &A = *CG1.lookup(lookupFunction(*M1, "a"));
+  LazyCallGraph::Node &B = *CG1.lookup(lookupFunction(*M1, "b"));
+  LazyCallGraph::Node &C = *CG1.lookup(lookupFunction(*M1, "c"));
+  EXPECT_EQ(&SCC, CG1.lookupSCC(A));
+  EXPECT_EQ(&SCC, CG1.lookupSCC(B));
+  EXPECT_EQ(&SCC, CG1.lookupSCC(C));
+
+  // Insert an edge from 'a' to 'c'. Nothing changes about the SCCs.
+  SCC.insertIntraSCCEdge(A, C);
+  EXPECT_EQ(2, std::distance(A.begin(), A.end()));
+  EXPECT_EQ(&SCC, CG1.lookupSCC(A));
+  EXPECT_EQ(&SCC, CG1.lookupSCC(B));
+  EXPECT_EQ(&SCC, CG1.lookupSCC(C));
+
+  // Insert a self edge from 'a' back to 'a'.
+  SCC.insertIntraSCCEdge(A, A);
+  EXPECT_EQ(3, std::distance(A.begin(), A.end()));
+  EXPECT_EQ(&SCC, CG1.lookupSCC(A));
+  EXPECT_EQ(&SCC, CG1.lookupSCC(B));
+  EXPECT_EQ(&SCC, CG1.lookupSCC(C));
+}
+
+TEST(LazyCallGraphTest, IntraSCCEdgeRemoval) {
+  // A nice fully connected (including self-edges) SCC.
+  std::unique_ptr<Module> M1 = parseAssembly(
+      "define void @a() {\n"
+      "entry:\n"
+      "  call void @a()\n"
+      "  call void @b()\n"
+      "  call void @c()\n"
+      "  ret void\n"
+      "}\n"
+      "define void @b() {\n"
+      "entry:\n"
+      "  call void @a()\n"
+      "  call void @b()\n"
+      "  call void @c()\n"
+      "  ret void\n"
+      "}\n"
+      "define void @c() {\n"
+      "entry:\n"
+      "  call void @a()\n"
+      "  call void @b()\n"
+      "  call void @c()\n"
+      "  ret void\n"
+      "}\n");
+  LazyCallGraph CG1(*M1);
+
+  // Force the graph to be fully expanded.
+  auto SCCI = CG1.postorder_scc_begin();
+  LazyCallGraph::SCC &SCC = *SCCI++;
+  EXPECT_EQ(CG1.postorder_scc_end(), SCCI);
+
+  LazyCallGraph::Node &A = *CG1.lookup(lookupFunction(*M1, "a"));
+  LazyCallGraph::Node &B = *CG1.lookup(lookupFunction(*M1, "b"));
+  LazyCallGraph::Node &C = *CG1.lookup(lookupFunction(*M1, "c"));
+  EXPECT_EQ(&SCC, CG1.lookupSCC(A));
+  EXPECT_EQ(&SCC, CG1.lookupSCC(B));
+  EXPECT_EQ(&SCC, CG1.lookupSCC(C));
+
+  // Remove the edge from b -> a, which should leave the 3 functions still in
+  // a single connected component because of a -> b -> c -> a.
+  SmallVector<LazyCallGraph::SCC *, 1> NewSCCs = SCC.removeIntraSCCEdge(B, A);
+  EXPECT_EQ(0u, NewSCCs.size());
+  EXPECT_EQ(&SCC, CG1.lookupSCC(A));
+  EXPECT_EQ(&SCC, CG1.lookupSCC(B));
+  EXPECT_EQ(&SCC, CG1.lookupSCC(C));
+
+  // Remove the edge from c -> a, which should leave 'a' in the original SCC
+  // and form a new SCC for 'b' and 'c'.
+  NewSCCs = SCC.removeIntraSCCEdge(C, A);
+  EXPECT_EQ(1u, NewSCCs.size());
+  EXPECT_EQ(&SCC, CG1.lookupSCC(A));
+  EXPECT_EQ(1, std::distance(SCC.begin(), SCC.end()));
+  LazyCallGraph::SCC *SCC2 = CG1.lookupSCC(B);
+  EXPECT_EQ(SCC2, CG1.lookupSCC(C));
+  EXPECT_EQ(SCC2, NewSCCs[0]);
+}
+
+}