Using a modified value GPR to enhance lookahead prefetch
US7620799B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 2, 2008 |
| Grant date | Nov 17, 2009 |
| Priority date | — |
| Expiry date | May 2, 2028 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F9/3838
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
Mechanisms to identify and speculatively execute future instructions during a stall condition are provided. In speculative mode, instruction operands may be invalid due to a number of reasons. Dependency and dirty bits are tracked and used to determine which speculative instructions are valid for execution. A modified value register storage and bit vector are used to improve the availability of speculative results that would otherwise be discarded once they leave the execution pipeline because they cannot be written to the architected registers. The modified general purpose registers are used to store speculative results when the corresponding instruction reaches writeback and the modified bit vector tracks the results that have been stored there. Younger speculative instructions that do not bypass directly from older instructions use this modified data when the corresponding bit in the modified bit vector indicates the data has been modified. Otherwise, data from the architected registers is used.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.