CrossDSOCFI - silence static analyzer dyn_cast<> null dereference warning. NFCI.

The static analyzer is warning about a potential null dereference, but we should be able to use cast<> directly and if not assert will fire for us.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@375427 91177308-0d34-0410-b5e6-96231b3b80d8

Author: RKSimon

lib/Transforms/IPO/CrossDSOCFI.cpp

@@ -104,7 +104,7 @@ void CrossDSOCFI::buildCFICheck(Module &M) {
   FunctionCallee C = M.getOrInsertFunction(
       "__cfi_check", Type::getVoidTy(Ctx), Type::getInt64Ty(Ctx),
       Type::getInt8PtrTy(Ctx), Type::getInt8PtrTy(Ctx));
-  Function *F = dyn_cast<Function>(C.getCallee());
+  Function *F = cast<Function>(C.getCallee());
   // Take over the existing function. The frontend emits a weak stub so that the
   // linker knows about the symbol; this pass replaces the function body.
   F->deleteBody();