https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63679
--- Comment #14 from jgreenhalgh at gcc dot gnu.org --- Yes, we turn move_by_pieces off for AArch64 so we can use our own expander for block moves. This has a number of negative side-effects where optimizers decide that if you're not using move_by_pieces, block moves must be expensive - this is bogus! (see Joern's email on the thread hookizing BY_PIECES_P https://gcc.gnu.org/ml/gcc-patches/2014-11/msg00197.html ).
