Reduced overhead address mode change management in a pipelined, recycling microprocessor

US7971034B2 · kind B2 · utility

Assignee

• International Business Machines Corporation · US

Inventors

• David S. Hutton · Poughkeepsie, US
• Michael Billeci · Poughkeepsie, US
• Fadi Y. Busaba · Poughkeepsie, US
• Brian R. Prasky · Campbell Hall, US
• John G. Rell, Jr. · Saugerties, US
• Chung-Lung K. Shum · Wappingers Falls, US
• Charles F. Webb · Wappingers Falls, US

Key dates

• Filing date: Mar 19, 2008
• Grant date: Jun 28, 2011
• Expiry date: Aug 30, 2029

Classification

• Technology area (CPC G): Physics
• CPC primary: G06F9/3867
• WIPO field: Computer technology
• WIPO sector: Electrical engineering

Abstract

A method, system, and computer program product for reduced overhead address mode change management in a pipelined, recycling microprocessor are provided. The recycling microprocessor includes logic executing thereon. The microprocessor also includes an instruction fetch unit (IFU) supporting computation of address adds in selected address modes and reporting non-equal comparison of the computation to the logic. The microprocessor further includes a fixed point unit determining whether the mode has changed and reporting changes to the logic. Upon determining the comparison yields an equal result but the mode has changed, a recycle event is triggered to ensure subsequent ofetches are relaunched in the correct mode and that no execution writebacks occur from work performed in an incorrect mode. For comparisons yielding a non-equal result and a changed mode, the logic clears bits set in response to the determinations, and a serialization event is taken to reset a corresponding pipeline for operation in the correct mode.