Use of the various address bit masks in GPIO

Harshavardhan Murali said:

noticed that the bits in the GPIODATA register are masked by the address bits [9:2]. What is the utility of such an implementation

You're describing, "Bit-Banding" are you not?    The absence of that term - and the nature of your question - seem to indicate higher focus upon the Register Listings than good read/consideration of the descriptive portion of the MCU manual.    Great detail resides therein - best results stem from good read of (both) MCU Registers (as you appear to have done) AND the narrative w/in the pertinent chapter of the MCU manual.

Devices without this "bit-banding" must execute a, "Read before Write" so that "non-targeted" bits are not negatively impacted by such writes.    Thus - through the elimination of that requirement - the write may be said to have been speeded.

I know the answer for your clock cycle question - but if that's of such interest - is it not better for you to invest time/effort in that discovery?     Key to much of MCU application & development success is, "Knowing how & where to find" critical/sought tech. information.    I won't deny you that pleasure...