发明授权
- 专利标题: Software hint to improve the branch target prediction accuracy
- 专利标题(中): 软件提示提高分支目标预测精度
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申请号: US09798166申请日: 2001-03-01
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公开(公告)号: US06823447B2公开(公告)日: 2004-11-23
- 发明人: Robert William Hay , Balaram Sinharoy
- 申请人: Robert William Hay , Balaram Sinharoy
- 主分类号: G06F900
- IPC分类号: G06F900
摘要:
A field is defined in branch instructions which is interpreted by software as “Hint” bits and these bits are used to signal the processor of special circumstances that may arise when doing speculative branch instruction execution to enable better branch address prediction accuracy and a reduction in link stack corruption which improves overall execution times. A programmer or compiler determines if a branch instruction usage fits in the context for a Hint action. If so, the compiler or programmer, using assembly/machine language, sets Hint bits in the branch instruction when it is compiled. If the branch is later speculatively executed, the processor decodes the Hint bits and executes and a hardware action corresponding the decode of the Hint bits. These Hints include four specific Hint actions, however, the field reserved for Hint bits is five bit wide reserving up to thirty-two specific Hint cases may be specified. These Hint cases (or Hint bits) may be interpreted differently for each type of branch instruction supported.