Extended Description
See http://google1.osuosl.org:8011/builders/clang-i686-linux-selfhost-rel/builds/18
Attached is a standalone c++ test case that shows the problem. It's not visible on darwin or x86_64-linux though.
$ clang++ v.cc && ./a.out
DEADBEEF
$ clang++ -O1 v.cc && ./a.out
0