http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53199
--- Comment #1 from Michael Meissner <meissner at gcc dot gnu.org> 2012-05-02 19:16:26 UTC --- If you compile the following with -mcpu=power6 -m64: long long b64 (long long *p) { return __builtin_bswap64 (*p); } Using the -mno-avoid-indexed-addresses works around the problem. Setting cpu=power5 works because -mcpu=power5 does not set -mavoid-indexed-addresses by default. Setting -mcpu=power7 works because the power7 has a 64-bit load and reverse bytes instruction.