Electrical computers and digital processing systems: processing – Processing control – Branching
Reexamination Certificate
2006-09-12
2006-09-12
Chan, Eddie (Department: 2183)
Electrical computers and digital processing systems: processing
Processing control
Branching
C712S237000
Reexamination Certificate
active
07107437
ABSTRACT:
A method and apparatus are provided for improving the performance of branch prediction using a combination of a speculative branch target buffer (SBTB) and an architectural branch target buffer (ABTB). According to one embodiment, speculative branch data is maintained for in-flight branches (i.e., those that have been fetched but not yet retired). A branch entry is speculatively allocated in a line of the SBTB after decoding an instruction containing a branch, such as a conditional branch, a return from a subroutine, a call to a subroutine, or an unconditional branch. Subsequently, the branch data associated with the branch entry is speculatively updated after branch prediction has been completed for the branch. Finally, the branch data is corrected after the branch has been executed. According to another embodiment, a novel branch prediction circuit includes both a speculative branch target buffer (SBTB) cache and an architectural branch target buffer (ABTB) cache. The SBTB cache contains multiple branch entries to maintain speculative branch data associated with in-flight branches. The speculative branch data includes a speculative history of taken
ot-taken outcomes associated with the in-flight branches. The ABTB cache is coupled to the SBTB cache. The ABTB cache also includes multiple branch entries, however, they are for maintaining architectural branch data including the actual taken
ot-taken outcomes associated with retired conditional branches.
REFERENCES:
patent: 5515518 (1996-05-01), Stiles et al.
patent: 5553255 (1996-09-01), Jain et al.
patent: 5584001 (1996-12-01), Hoyt et al.
patent: 5732253 (1998-03-01), McMahan
patent: 5774710 (1998-06-01), Chung
patent: 5842008 (1998-11-01), Gochman et al.
patent: 5978909 (1999-11-01), Lempel
patent: 6067616 (2000-05-01), Stiles et al.
patent: 6185668 (2001-02-01), Arya
patent: 6321328 (2001-11-01), Karp et al.
patent: 6513109 (2003-01-01), Gschwind et al.
patent: 6553488 (2003-04-01), Yeh et al.
Blakely , Sokoloff, Taylor & Zafman LLP
Chan Eddie
Li Aimee J.
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