http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49007
--- Comment #3 from John David Anglin <danglin at gcc dot gnu.org> 2011-05-16 01:35:28 UTC --- By trial and error, it appears tree-cfgcleanup.c is miscompiled at -O1 without -fno-delayed-branch.
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49007
--- Comment #3 from John David Anglin <danglin at gcc dot gnu.org> 2011-05-16 01:35:28 UTC --- By trial and error, it appears tree-cfgcleanup.c is miscompiled at -O1 without -fno-delayed-branch.