Method and apparatus to reduce penalty of microcode lookup
US6789186B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 18, 2000 |
| Grant date | Sep 7, 2004 |
| Priority date | — |
| Expiry date | Feb 18, 2020 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F9/30174
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A method and apparatus are provided for improving the rate at which macroinstructions are transformed into corresponding microinstructions. Encoding is added to a microcode storage device. The encoding indicates that a microinstruction flow will end in a determined number of cycles. The number of cycles is determined by the number of canceled instructions in a processing pipeline that would be introduced if no flow length prediction was used. For flow lengths less than a determined number of cycles, a hint bit is used in an entry point structure. For flow lengths greater than a determined length, a hint bit is encoded at a third line from an end of the microinstruction flow. Using this method, flows of any length can be hinted. Furthermore, flows that do not originate from the entry point structure can also be hinted. The method reduces the number of hint bits that are needed in the entry point structure and provides for better prediction.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.