AArch64: assert code model is small for TLS accesses

Supporting TLS in the large memory model is rather difficult at the
moment, so make sure no-one gets into difficulties by mistake.

llvm-svn: 181121

lib/Target/AArch64/AArch64ISelLowering.cpp

@@ -2025,6 +2025,8 @@ AArch64TargetLowering::LowerGlobalTLSAddress(SDValue Op,
                                              SelectionDAG &DAG) const {
   assert(Subtarget->isTargetELF() &&
          "TLS not implemented for non-ELF targets");
+  assert(getTargetMachine().getCodeModel() == CodeModel::Small
+         && "TLS only supported in small memory model");
   const GlobalAddressSDNode *GA = cast<GlobalAddressSDNode>(Op);
 
   TLSModel::Model Model = getTargetMachine().getTLSModel(GA->getGlobal());