Software hint to improve the branch target prediction accuracy
US6823447B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 1, 2001 |
| Grant date | Nov 23, 2004 |
| Priority date | — |
| Expiry date | Jan 9, 2023 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F9/3846
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.