https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67351
--- Comment #2 from Uroš Bizjak <ubizjak at gmail dot com> --- (In reply to Allan Jensen from comment #0) > Gcc will expand and detect field setting on 32-bit integers, but for some > reason miss the opportunity on 64-bit. The immediates for 64bit logic insns are limited to sign-extended 32bit values, so this probably limits combine to combine several insns into one.
