AHB HSIZE usage

Hi,

In AMBA® 3 AHB-Lite Protocol, there is a description about the HSIZE signal:

"The transfer size set by HSIZE must be less than or equal to the width of the data bus.
For example, with a 32-bit data bus, HSIZE must only use the values b000, b001, or
b010. "

If our design is 23-bit bus, HSIZE could be set to 8/16/32-bit.

My question is: In what situation does the compiler decide use 8-bit or 16-bit?