Assert that we have all use/users in the getters.

An error that is pretty easy to make is to use the lazy bitcode reader
and then do something like

if (V.use_empty())

The problem is that uses in unmaterialized functions are not accounted
for.

This patch adds asserts that all uses are known.

llvm-svn: 256105
diff --git a/llvm/lib/IR/Value.cpp b/llvm/lib/IR/Value.cpp
index 925f205..eb9deb6 100644
--- a/llvm/lib/IR/Value.cpp
+++ b/llvm/lib/IR/Value.cpp
@@ -314,6 +314,16 @@
 }
 
 #ifndef NDEBUG
+void Value::assertModuleIsMaterialized() const {
+  const GlobalValue *GV = dyn_cast<GlobalValue>(this);
+  if (!GV)
+    return;
+  const Module *M = GV->getParent();
+  if (!M)
+    return;
+  assert(M->isMaterialized());
+}
+
 static bool contains(SmallPtrSetImpl<ConstantExpr *> &Cache, ConstantExpr *Expr,
                      Constant *C) {
   if (!Cache.insert(Expr).second)