[test] Factor out creation of copy of SCC Nodes into function

[rnk]

lgtm

llvm/unittests/Analysis/CGSCCPassManagerTest.cpp

CGPM.addPass(LambdaSCCPassNoPreserve(
         ASSERT_NO_FATAL_FAILURE(CGU.removeFunction(*FnH2));
       }));
 
   ModulePassManager MPM(/*DebugLogging*/ true);
   MPM.addPass(createModuleToPostOrderCGSCCPassAdaptor(std::move(CGPM)));
   MPM.run(*M, MAM);
 }
 
+// Returns a vector containing the SCC's nodes. Useful for not iterating over an
+// SCC while mutating it.
+static SmallVector<LazyCallGraph::Node *> SCCNodes(LazyCallGraph::SCC &C) {
+  SmallVector<LazyCallGraph::Node *> Nodes;
+  for (auto &N : C)
+    Nodes.push_back(&N);
+
+  return Nodes;
+}
+
 // Start with call recursive f, create f -> g and ref recursive f.
 TEST_F(CGSCCPassManagerTest, TestInsertionOfNewFunctions1) {
   std::unique_ptr<Module> M = parseIR("define void @f() {\n"
                                       "entry:\n"
                                       "  call void @f()\n"
                                       "  ret void\n"
                                       "}\n");
 
   bool Ran = false;
 
   CGSCCPassManager CGPM(/*DebugLogging*/ true);
   CGPM.addPass(LambdaSCCPassNoPreserve(
       [&](LazyCallGraph::SCC &C, CGSCCAnalysisManager &AM, LazyCallGraph &CG,
           CGSCCUpdateResult &UR) {
         if (Ran)
           return;
 
         auto &FAM =
             AM.getResult<FunctionAnalysisManagerCGSCCProxy>(C, CG).getManager();
 
-        // Don't iterate over SCC while changing it.
-        SmallVector<LazyCallGraph::Node *> Nodes;
-        for (auto &N : C)
-          Nodes.push_back(&N);
-
-        for (LazyCallGraph::Node *N : Nodes) {
+        for (LazyCallGraph::Node *N : SCCNodes(C)) {
           Function &F = N->getFunction();
           if (F.getName() != "f")
             continue;
 
           // Create a new function 'g'.
           auto *G = Function::Create(F.getFunctionType(), F.getLinkage(),
                                      F.getAddressSpace(), "g", F.getParent());
           auto *GBB =
CGPM.addPass(LambdaSCCPassNoPreserve([&](LazyCallGraph::SCC &C,
                                            LazyCallGraph &CG,
                                            CGSCCUpdateResult &UR) {
     if (Ran)
       return;
 
     auto &FAM =
         AM.getResult<FunctionAnalysisManagerCGSCCProxy>(C, CG).getManager();
 
-    // Don't iterate over SCC while changing it.
-    SmallVector<LazyCallGraph::Node *> Nodes;
-    for (auto &N : C)
-      Nodes.push_back(&N);
-
-    for (LazyCallGraph::Node *N : Nodes) {
+    for (LazyCallGraph::Node *N : SCCNodes(C)) {
       Function &F = N->getFunction();
       if (F.getName() != "f")
         continue;
 
       // Create mutually recursive functions (call) 'g1' and 'g2'.
       auto *G1 = Function::Create(F.getFunctionType(), F.getLinkage(),
                                   F.getAddressSpace(), "g1", F.getParent());
       auto *G2 = Function::Create(F.getFunctionType(), F.getLinkage(),
CGPM.addPass(LambdaSCCPassNoPreserve([&](LazyCallGraph::SCC &C,
                                            LazyCallGraph &CG,
                                            CGSCCUpdateResult &UR) {
     if (Ran)
       return;
 
     auto &FAM =
         AM.getResult<FunctionAnalysisManagerCGSCCProxy>(C, CG).getManager();
 
-    // Don't iterate over SCC while changing it.
-    SmallVector<LazyCallGraph::Node *> Nodes;
-    for (auto &N : C)
-      Nodes.push_back(&N);
-
-    for (LazyCallGraph::Node *N : Nodes) {
+    for (LazyCallGraph::Node *N : SCCNodes(C)) {
       Function &F = N->getFunction();
       if (F.getName() != "f1")
         continue;
 
       Function *F3 = F.getParent()->getFunction("f3");
       ASSERT_TRUE(F3 != nullptr);
 
       // Create call from f1 to f3.