A compiler-assisted lookahead (CAL) memory system for a CAL microprocessor consisting of a CAL memory management unit, a CAL lookahead instruction (LI) and compatible instruction (CI) memory system, and a CAL LI and CI cache system, is designed for operating with a CAL frontend processor to fetch LIs and CIs in a lookahead manner and to reorder the LIs/CIs fetched before decoding them for producing compatible results of the program. The invention is for enhancing performance and energy-efficiency of loop operations by reusing the LIs and CIs in the loops without fetching them iteratively from the CAL memory system.