http://gcc.gnu.org/bugzilla/show_bug.cgi?id=10474
--- Comment #12 from Martin Jambor <jamborm at gcc dot gnu.org> --- I have submitted a different patch that addresses this issue, this time by splitting live ranges of pseudos representing the formal parameters of a function. The patch is pending review/approval and the current version is at http://gcc.gnu.org/ml/gcc-patches/2013-10/msg02183.html
