[analyzer] Consider function call arguments while building CallGraph

[IvanSidorenko]

Summary

Function call can appear in the arguments of another function call. This patch adds support for such cases.

[NoQ]

LGTM!

lib/Analysis/CallGraph.cpp

if (G->includeInGraph(D)) {
       CallGraphNode *CalleeNode = G->getOrInsertNode(D);
       CallerNode->addCallee(CalleeNode);
     }
   }
 
   void VisitCallExpr(CallExpr *CE) {
     if (Decl *D = getDeclFromCall(CE))
       addCalledDecl(D);
+    VisitChildren(CE);
   }
 
   // Adds may-call edges for the ObjC message sends.
   void VisitObjCMessageExpr(ObjCMessageExpr *ME) {
     if (ObjCInterfaceDecl *IDecl = ME->getReceiverInterface()) {
       Selector Sel = ME->getSelector();
       
       // Find the callee definition within the same translation unit.

test/Analysis/debug-CallGraph.c

 // RUN: %clang_cc1 -analyze -analyzer-checker=debug.DumpCallGraph %s -fblocks 2>&1 | FileCheck %s
 
+int get5() {
+  return 5;
+}
+
+int add(int val1, int val2) {
+  return val1 + val2;
+}
+
+int test_add() {
+  return add(10, get5());
+}
+
 static void mmm(int y) {
   if (y != 0)
       y++;
   y = y/y;
 }
 
 static int foo(int x, int y) {
     mmm(y);

 void ddd() { ccc(); }
 void ccc() {}
 
 void eee();
 void eee() {}
 void fff() { eee(); }
 
 // CHECK:--- Call graph Dump ---
-// CHECK-NEXT: {{Function: < root > calls: mmm foo aaa < > bbb ccc ddd eee fff $}}
+// CHECK-NEXT: {{Function: < root > calls: get5 add test_add mmm foo aaa < > bbb ccc ddd eee fff $}}
 // CHECK-NEXT: {{Function: fff calls: eee $}}
 // CHECK-NEXT: {{Function: eee calls: $}}
 // CHECK-NEXT: {{Function: ddd calls: ccc $}}
 // CHECK-NEXT: {{Function: ccc calls: $}}
 // CHECK-NEXT: {{Function: bbb calls: < > $}}
 // CHECK-NEXT: {{Function: < > calls: foo $}}
 // CHECK-NEXT: {{Function: aaa calls: foo $}}
 // CHECK-NEXT: {{Function: foo calls: mmm $}}
 // CHECK-NEXT: {{Function: mmm calls: $}}
+// CHECK-NEXT: {{Function: test_add calls: add get5 $}}
+// CHECK-NEXT: {{Function: add calls: $}}
+// CHECK-NEXT: {{Function: get5 calls: $}}