https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103850
--- Comment #2 from Martin Reinecke <mar...@mpa-garching.mpg.de> --- Thanks! This flag indeed causes both kernels to have the same speed, but (at least for me) it's slower than both original versions... slow kernel version: 29.027915 GFlops/s fast kernel version: 29.008313 GFlops/s Strange.