Method and apparatus for updating global branch history information

An apparatus for updating global branch history (GBH) information within a data processing system, said apparatus comprising:

• a branch history table having a plurality of entries, each entry is associated with a branch instruction;
• a global branch history buffer contains GBH information of a plurality of most recent branch instructions, wherein said GBH information to used to index to said branch history table to obtain a prediction signal;
• and
• means for immediately shifting zero, one or more of GBH bits into said global branch history buffer, in response to a fetch group of instructions, wherein a fetch group containing or predicted to contain no taken branch is represented by the same pattern of said GBH bits regardless of the number of branch instructions within said fetch group of instructions.

A computer program product residing on a computer usable medium for updating global branch history (GBH) information within a data processing system, said computer program product comprising:

• program code means for providing a branch history table having a plurality of entries, each entry is associated with a branch instruction;
• program code means for providing a global branch history buffer contains GBH information of a plurality of most recent branch instructions, wherein said GBH information to used to index to said branch history table to obtain a prediction signal;
• and
• program code means for immediately shifting zero, one or more of GBH bits into said global branch history buffer, in response to a fetch group of instructions, wherein a fetch group containing or predicted to contain no taken branch is represented by the same pattern of said GBH bits regardless of the number of branch instructions within said fetch group of instructions.