Advanced Micro Devices Corporation

Globalfoundries Inc.

Trivikram Krishnamurthy

Marius Evers

Anthony Jarvis

A branch predictor for use in a processor includes a Level 1 branch predictor, a Level 2 branch predictor, a match determining circuit, and an override determining circuit. The Level 1 branch predictor generates a Level 1 branch prediction. The Level 2 branch predictor generates a Level 2 branch prediction. The match determining circuit determines whether the Level 1 and Level 2 branch predictions match. The override determining circuit determines whether to override the Level 1 branch prediction with the Level 2 branch prediction. The Level 1 branch prediction is used when the Level 1 and Level 2 branch predictions match or when the Level 1 and Level 2 branch predictions do not match and the Level 1 branch prediction is not overridden. The Level 2 branch prediction is used when the Level 1 and Level 2 branch predictions do not match and the Level 1 branch prediction is overridden.

Combined level 1 and level 2 branch predictor

An apparatus for executing branch predictor directed prefetch operations. During operation, a branch prediction unit may provide an address of a first instruction to the fetch unit. The fetch unit may send a fetch request for the first instruction to the instruction cache to perform a fetch operation. In response to detecting a cache miss corresponding to the first instruction, the fetch unit may execute one or more prefetch operation while the cache miss corresponding to the first instruction is being serviced. The branch prediction unit may provide an address of a predicted next instruction in the instruction stream to the fetch unit. The fetch unit may send a prefetch request for the predicted next instruction to the instruction cache to execute the prefetch operation. The fetch unit may store prefetched instruction data obtained from a next level of memory in the instruction cache or in a prefetch buffer.

Growing community of inventors

Sunnyvale, CA, United States of America

Trivikram Krishnamurthy