http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57439
--- Comment #4 from Jorn Wolfgang Rennecke <amylaar at gcc dot gnu.org> --- Created attachment 30209 --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=30209&action=edit experimental patch I've used -I to point the compiler to the include directory in the newlib sources, and from what I see them, the problem is that a narrow register is generated by using the original REGNO and the new narrow mode - this misses the big endian correction. This patch uses gen_lowpart_common, which should just DTRT regardless of endianness. A further observation is that previously a conversion to a DImode add of 4 was tried, and abandoned, presumably due to cost. A SImode add to the 32 bit lowpart would be more profitable, at least if the target supports addq.l . In general, we should try if a set or constant add with a destination that is a subreg that constitutes one (or more) full hard register(s) is the cheapest option.
