https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68416
--- Comment #4 from Ilya Enkovich <ienkovich at gcc dot gnu.org> --- (In reply to Vladimir Makarov from comment #3) > The first I thought it is a LRA inheritance bug but after more thorough > analysis I found that the problem comes from IRA. IRA never assigns BND > hard registers to pseudos because it never assigns BNDREGS class to pseudos. > After some investigation I found that ALL_REGS does not contain BNDREGS. > IRA starts with ALL_REGS and uses narrow reg class if the mode is prohibited > for some hard registers. That is why class BNDREGS is never used for > pseudos. Thanks a lot for the patch! It significantly improves MPX code quality.