Reducing branch checking for non control flow instructions
AssigneeSTMicroelectronics (Beijing) R&D Co., Ltd.
InventorsKai-Feng Wang, Hong-Xia Sun, Yong-Qiang Wu
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Abstract
Some microprocessors check branch prediction information in a branch history table and/or a branch target buffer. To check for branch prediction information, a microprocessor can identify which instructions are control flow instructions and which instructions are non control flow instructions. To reduce power consumption in the branch history table and/or branch target buffer, the branch history table and/or branch target buffer can check for branch prediction information corresponding to the control flow instructions and not the non control flow instructions.
Claims15
A microprocessor for executing instructions, wherein the microprocessor fetches a group of instructions comprising at least one control flow instruction and at least one non control flow instruction, the microprocessor comprising:
- a control instruction identification unit that stores control instruction identification information identifying the at least one non control flow instruction in the fetched group of instructions;
- and
- a branch prediction unit that checks for branch prediction information corresponding to the at least one control flow instruction and does not check for branch prediction information corresponding to the at least one non control flow instruction.
In a microprocessor that executes instructions, a method of checking branch prediction information, the method comprising:
- fetching a group of instructions comprising at least one control flow instruction and at least one non control flow instruction;
- and
- checking a branch prediction unit for branch prediction information corresponding to the at least one control flow instruction and not the at least one non control flow instruction.
Dependencies are inferred from the claim text.