Pipeline having bifurcated global branch history buffer for indexing branch history table per instruction fetch group
US7454602B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 15, 2004 |
| Grant date | Nov 18, 2008 |
| Priority date | — |
| Expiry date | Nov 24, 2025 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F9/3848
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A method and apparatus for updating global branch history information are disclosed. A dynamic branch predictor within a data processing system includes a global branch history (GBH) buffer and a branch history table. The GBH buffer contains GBH information of a group of the most recent branch instructions. The branch history table includes multiple entries, each entry is associated with one or more branch instructions. The GBH information from the GBH buffer can be used to index into the branch history table to obtain a branch prediction signal. In response to a fetch group of instructions, a fixed number of GBH bits is shifted into the GBH buffer. The number of GBH bits is the same regardless of the number of branch instructions within the fetch group of instructions. In addition, there is a unique bit pattern associated with the case of no taken branch in the fetch group, regardless of the number of not-taken branches of even if there are any branches in the fetch group.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.