https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103252
--- Comment #8 from Jakub Jelinek <jakub at gcc dot gnu.org> --- Definitely not lazier. When the mask registers are available for use, RA considers them and when spilling to those is cheaper than to memory, it spills to them and not memory. Where cheaper is determined by the gcc cost model, which tries to approximately model the hw, but on real hw whether it is beneficial or not may depend on various other details that perhaps aren't even considered.
