Method and apparatus for back to back issue of dependent instructions in an out of order issue queue
US7669038B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | May 2, 2008 |
| Grant date | Feb 23, 2010 |
| Priority date | — |
| Expiry date | Aug 8, 2028 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F9/3838
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A method is provided for evaluating two or more instructions in an out of order issue queue during a particular cycle of the queue, to select an instruction for issue during the next following cycle. If an instruction was previously designated to issue during the particular cycle, one or more instructions in the queue are evaluated to determine if any of them are dependent on the designated instruction. For the evaluation, each instruction placed into the queue is accompanied by corresponding logic elements that provide destination to source compares for the instruction. In an embodiment comprising a method, the oldest ready instruction in the queue during a particular cycle is identified. When an instruction was previously designated to issue during the particular cycle, it is determined whether at least a first instruction in the queue complies with each condition in a set of conditions, the set including at least the conditions that the first instruction has a dependency on the designated instruction, and that the first instruction is older than the oldest ready instruction. The first instruction is selected for issue during the next following cycle only if the first instruction…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.