Looks like LLVM is inferring nonnull on some tests, and that is causing FileCheck directives to fail in clang -O1: http://lab.llvm.org:8011/builders/clang-cmake-thumbv7-a15/builds/5826/steps/ninja%20check%201/logs/FAIL%3A%20Clang%3A%3Ainit-invariant.cpp -- Sanjoy