Branch prediction with partially folded global history vector for reduced XOR operation time
US7689816B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Jan 31, 2008 |
| Grant date | Mar 30, 2010 |
| Priority date | — |
| Expiry date | Apr 24, 2028 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F9/3848
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A global history vector (GHV) mechanism maintains a folded (XORed) GHV with higher order entries and an unfolded (no XORed) GHV with lower order entries. When a new entry arrives at the GHV, the GHV mechanism performs an XOR of the oldest unfolded entry in the unfolded GHV with the new entry. The XOR result is then shifted into the folded GHV as the newest folded entry. The oldest folded entry is discarded during the shift in of the newest folded entry. The GHV mechanism thus provides a resulting folded GHV that is current and can be utilized for XORing with an IFAR by performing an XOR operation. Only a single XOR logic is required to perform a single bit XOR operation between the oldest entry and the youngest entry, resulting in reducing the cycle time required to complete the folding (XORing) operation on a GHV.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.