> For memory operands, there's an additional twist: the bit index is a signed offset that can address bits outside the nominal operand. A bit index of 35 on a dword accesses bit 3 of the next dword in memory.
I wonder what is the use case for testing a bit outside of the memory address given.
It was probably easier to just implement it that way, given that the barrel shifter is 64 bits wide.
So you can have bit arrays of any length in memory, rather than just 32 bits in a register.