http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52558
--- Comment #3 from Andrew Macleod <amacleod at redhat dot com> 2012-03-12 15:24:35 UTC --- Created attachment 26881 --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=26881 Testcase for simulate-threads I've modified the testcase so that it runs in gcc.dg/simulate-thread as a pass/fail. Clearly it currently fails, although its interesting because at -O3 it passes again!! The second pass of DOM undoes the extra write! It does fail the testsuite at -O2 as expected. This diff can be applied to add it to simulate threads.