I assume you meant GDB, not GCC, right?

Seems like a deficiency in GDB (and maybe LLDB too), not in the kernel or x86.

I do mean GCC. Whoops.

Deficiency or not, it breaks debugging. I’m willing to pay a cost of one byte per breakpoint as a workaround.

And GDB has far more outrageous, if less-frequently hit, bugs in its architectural state handling. I’m not holding my breath for a fix.