When the Quartus II software decides the functions in an ALM?

In the QUIP design flow, Quartus II will first do technology mapping and then P&R.

If the technology mapping used in the Quartus II is cut-based mapping, when the software decides which one or two LUTs should form an ALM?

My guess is, there are two possible ways, one is a extra step after technology mapping and before P&R. The other one is simultaneously processed in the P&R step.

Since I didn't found any specific info of that, may anyone tell me about where to find them or share some details?

Best Regards,

Student Tien-Yu Kuo