Rewriting branch instructions using branch stubs

US8522225B2 · kind B2 · utility

Assignee

• International Business Machines Corporation · US

Inventors

• Tong Chen · Brookline, US
• Brian Flachs · Austin, US
• Brad W. Michael · Cedar Park, US
• Mark Richard Nutter · Austin, US
• John Kevin Patrick O'Brien · South Salem, US
• Kathryn M. O'Brien · South Salem, US
• Tao Zhang · Beijing, CN

Key dates

• Filing date: Jun 25, 2010
• Grant date: Aug 27, 2013
• Expiry date: Jul 17, 2031

Classification

• Technology area (CPC G): Physics
• CPC primary: G06F8/4442
• WIPO field: Computer technology
• WIPO sector: Electrical engineering

Abstract

Mechanisms are provided for rewriting branch instructions in a portion of code. The mechanisms receive a portion of source code having an original branch instruction. The mechanisms generate a branch stub for the original branch instruction. The branch stub stores information about the original branch instruction including an original target address of the original branch instruction. Moreover, the mechanisms rewrite the original branch instruction so that a target of the rewritten branch instruction references the branch stub. In addition, the mechanisms output compiled code including the rewritten branch instruction and the branch stub for execution by a computing device. The branch stub is utilized by the computing device at runtime to determine if execution of the rewritten branch instruction can be redirected directly to a target instruction corresponding to the original target address in an instruction cache of the computing device without intervention by an instruction cache runtime system.