https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78671
--- Comment #4 from Uroš Bizjak <ubizjak at gmail dot com> --- (In reply to Vladimir Makarov from comment #3) > It has just triggered a latent bug. It is a pretty interesting bug. The > problem is that a TImode pseudo has class INT_SSE_REGS and r15(44) smoothly > goes to xmm8 (45). So using available regs in LRA, r15 is ok for the pseudo. > > Actually on machine-depended side, a more detail implementation > HARD_REGNO_MODE_OK could solve the problem. But it is too complicated and > error prone and require a lot of efforts to define the macro accurately for > all classes and modes. On machine-dependend side, there is HARD_REGNO_NREGS macro that should be taken into account when allocating modes that live in multiple registers. This macro returns 2 for r15 in TImode. There is no r16 available, so r15 should be rejected as a TImode register from the beginning.
