http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54953
--- Comment #2 from Alexandre Oliva <aoliva at gcc dot gnu.org> 2012-10-26 07:42:07 UTC --- Without your poposed change, AFTER_WITH_REG is only used while adding REG_UNUSED marks to REG defs. That the REG def is unused means it's going to be discarded and, when it is, either the debug temp will be reset altogether, or we'll propagate the expression stored in the REG to uses of the REG (e.g., the debug use, if we omit the debug temp, or the debug temp, if we needlessly add it), or we (should?) emit another debug temp BEFORE_WITH_VALUE and use that instead of the REG (in the orginal debug use or in the needless debug temp). In any of these cases, the debug temp is useless. All that siad, it's probably not a terribly important optimization, so if the above wouldn't make sense in a comment before the questionable hunk, we might as well drop it. Adding REG_FORCE for this new use is probably fine too.
