Invention Grant
- Patent Title: Apparatus and method for making predictions for instruction flow changing instructions
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Application No.: US16364557Application Date: 2019-03-26
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Publication No.: US11379239B2Publication Date: 2022-07-05
- Inventor: Yasuo Ishii , Muhammad Umar Farooq
- Applicant: Arm Limited
- Applicant Address: GB Cambridge
- Assignee: Arm Limited
- Current Assignee: Arm Limited
- Current Assignee Address: GB Cambridge
- Agency: Nixon & Vanderhye P.C.
- Main IPC: G06F15/00
- IPC: G06F15/00 ; G06F9/30 ; G06F9/38 ; G06F9/32

Abstract:
An apparatus and method are provided for making predictions for instruction flow changing instructions. The apparatus has a fetch queue that identifies a sequence of instructions to be fetched for execution by execution circuitry, and prediction circuitry for making predictions in respect of instruction flow changing instructions, and for controlling which instructions are identified in the fetch queue in dependence on the predictions. The prediction circuitry has a target prediction storage used to identify target addresses for instruction flow changing instructions that are predicted as taken. The target prediction storage comprises at least one entry that is configurable as a multi-taken entry to indicate that a source instruction flow changing instruction identified by that entry is a first instruction flow changing instruction with an associated first target address that identifies a series of instructions that is expected to exhibit static behaviour and that terminates with a second instruction flow changing instruction, where the second instruction flow changing instruction is unconditionally taken and has an associated second target address. The prediction circuitry is arranged, when making a prediction for a chosen instruction flow changing instruction that is identified by a multi-taken entry in the target prediction storage, to identify with reference to target address information stored in that multi-taken entry both the series of instructions and a target instruction at the second target address. It then causes the series of instructions and the target instruction to be identified in the fetch queue, and begins making further predictions starting from the target instruction at the second target address.
Public/Granted literature
- US20200310811A1 APPARATUS AND METHOD FOR MAKING PREDICTIONS FOR INSTRUCTION FLOW CHANGING INSTRUCTIONS Public/Granted day:2020-10-01
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