Cache memory control device, semiconductor integrated circuit, and cache memory control method

A semiconductor integrated circuit, comprising:

• a plurality of cache memories shared by a plurality of arithmetic processing units to store data from the plurality of arithmetic processing unit;
• a plurality of buses that are shared by the arithmetic processing units and transfers data read from the plurality of cache memories to the arithmetic processing units;
• an instruction execution unit that accesses each of the plurality of cache memories in accordance with cycles time-divided for each of the plurality of cache memories, executes an access instruction from the arithmetic processing unit to access data stored in each of the plurality of cache memories, and transfers data read from each of the cache memories to the bus corresponding to the arithmetic processing unit;
• an instruction feeding unit that receives an access instruction from the arithmetic processing unit and feeds the access instruction to the instruction execution unit while inhibiting feeding of a subsequent access instruction accessing a same cache memory with a preceding access instruction in a period required to execute the preceding access instruction and inhibiting feeding of the subsequent access instruction, for which the same bus as that used for the preceding access instruction is used in a predetermined period shorter than the period required to execute the preceding access instruction;
• a late flag setting unit that sets a late flag in association with the subsequent access instruction when the instruction feeding unit feeds the subsequent access instruction in the period required to execute the preceding access instruction, and
• a timing control unit that controls the instruction executing unit such that the instruction executing unit starts transferring data corresponding to the access instruction to which the late flag is set to the bus just after completing transfer of the data corresponding to the preceding access instruction to the bus, when an access instruction to which a late flag is set by the late flag setting unit is executed.

A cache memory control method that is performed by a cache memory control device, the cache memory control method comprising:

• accessing each of plurality of cache memories shared by arithmetic processing units according to cycles time-divided for each of the plurality of cache memories to execute an access instruction from one of the arithmetic processing units to one of the cache memories;
• transferring data read from each of the cache memories to one of buses corresponding to the arithmetic processing unit, the buses being shared by the arithmetic processing units to transfer the data read from the plurality of cache memories to the arithmetic processing unit;
• receiving an access instruction from the arithmetic processing unit to the cache memory;
• feeding the access instruction to an instruction execution unit while inhibiting feeding of a subsequent access instruction accessing a same cache memory with a preceding access instruction in a period required to execute the preceding access instruction and inhibiting feeding of the subsequent access instruction for which a same bus as that used for the preceding access instruction is used in a predetermined period shorter than the period required to execute the preceding access instruction;
• setting a late flag in association with the subsequent access instruction when the subsequent access instruction in the period required to execute the preceding access instruction is fed, and
• when an access instruction to which a late flag is set, controlling the feeding such that the feeding includes starting transferring data corresponding to the access instruction to which the late flag is set to the bus just after completing transfer of the data corresponding to the preceding access instruction to the bus.