发明授权
- 专利标题: Method and apparatus for back to back issue of dependent instructions in an out of order issue queue
- 专利标题(中): 方法和装置,用于在乱序问题队列中反向发布依赖指令
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申请号: US12114010申请日: 2008-05-02
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公开(公告)号: US07669038B2公开(公告)日: 2010-02-23
- 发明人: William Elton Burky , Raymond Cheung Yeung
- 申请人: William Elton Burky , Raymond Cheung Yeung
- 申请人地址: US NY Armonk
- 专利权人: International Business Machines Corporation
- 当前专利权人: International Business Machines Corporation
- 当前专利权人地址: US NY Armonk
- 代理机构: Yee & Associates, P.C.
- 代理商 Libby Z. Handelsman
- 主分类号: G06F9/30
- IPC分类号: G06F9/30
摘要:
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 complies with each condition in the set.
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