1.3 What is an R10000 Microprocessor?

Branch Unit

has the following characteristics:

• it allows one branch per cycle
• conditional branches can be executed speculatively, up to 4-deep
• it has a 44-bit adder to compute branch addresses
• it has a 4-quadword branch-resume buffer, used for reversing mispredicted speculatively-taken branches

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• the Branch Return Cache contains four instructions following a subroutine call, for rapid use when returning from leaf subroutines
• it has program trace RAM that stores the program counter for each instruction in the pipeline

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