On 15/09/2015 20:45, Richard Henderson wrote: > + /* Fold the global and local enable bits together into the > + global fields, then xor to show which registers have > + changed collective enable state. */ > + int mod = ((old_dr7 | old_dr7 * 2) ^ (new_dr7 | new_dr7 * 2)) & 0xff;
The AND is not needed at all but, if you add it, you might as well use "& 0xaa" which is clearer. But even better, just do: target_ulong old_dr7 = env->dr[7]; int mod = old_dr7 ^ new_dr7; ... if ((mod & ~0xff) == 0) { and test with if (mod & (3 << i * 2)) inside the loop. Otherwise looks good, I'll write a kvm-unit-tests patch for this. Paolo