Kenneth W Shoemaker

US Patent:

60887931, Jul 11, 2000

Filed:

Dec 30, 1996

Appl. No.:

8/777237

Inventors:

Kin-Yip Liu - Millbrae CA
Millind Mital - South San Francisco CA
Kenneth Shoemaker - Los Altos Hills CA

Assignee:

Intel Corporation - Santa Clara CA

International Classification:

G06F 938

US Classification:

712239

Abstract:

A microprocessor capable of predicting program branches includes a fetching unit, a branch prediction unit, and a decode unit. The fetching unit is configured to retrieve program instructions, including macro branch instructions. The branch prediction unit is configured to receive the program instructions from the fetching unit, analyze the program instructions to identify the macro branch instructions, determine a first branch prediction for each of the macro branch instructions, and direct the fetching unit to retrieve the program instructions in an order corresponding to the first branch predictions. The decode unit is configured to receive the program instructions in the order determined by the branch prediction unit, break down the program instructions into micro-operations, and determine a decoded branch micro-operation corresponding to each of the macro branch instructions requiring verification, such that each of the decoded branch micro-operations has a decoded branch outcome of taken, if the first branch prediction is incorrect, and not taken if the first branch prediction is correct. The microprocessor may also include an execution engine configured to execute the micro-operations and determine the decoded branch outcome for each of the decoded branch micro-operations and communicate each decoded branch outcome of taken to the fetching unit such that the fetching unit can re-retrieve the program instructions in a corrected order corresponding to each incorrect first branch prediction.