Patent ID: 6502188
Filing Date: 2002-12-31
Classification: G06F

Abstract:
A branch prediction mechanism comprising:a local branch prediction storage coupled to receive a fetch address, wherein said fetch address corresponds to a group of contiguous instruction bytes being fetched from an instruction cache, wherein said local branch prediction storage is configured to convey a local branch prediction; and a global branch prediction storage coupled to receive said fetch address and a global history, wherein said fetch address and said global history are combined to form an index, and wherein said index is used to select a global branch prediction from said global branch prediction storage; and a branch target storage coupled to receive said fetch address, wherein said target storage is configured to store a branch target address corresponding to said fetch address, wherein said target storage is configured to store a classification indicator corresponding to a branch having said branch target address, and wherein said indicator is initialized to indicate said branch is a local branch, and wherein said indicator is updated to indicate said branch is a global branch in response to detecting a first condition; and a selection device configured to select said local branch prediction in response to detecting said indicator indicates said branch is a local branch, and wherein said selection device is configured to select said global branch prediction in response to detecting said indicator indicates said branch is a global branch.