发明授权
US5632023A Superscalar microprocessor including flag operand renaming and forwarding apparatus 失效
超标量微处理器包括标志操作数重命名和转发设备

Superscalar microprocessor including flag operand renaming and
forwarding apparatus
摘要:
A superscalar microprocessor is provided with a reorder buffer for storing the speculative state of the microprocessor and a register file for storing the real state of the microprocessor. A flags register stores the real state of flags that are updated by flag modifying instructions which are executed by the functional units of the microprocessor. To enhance the performance of the microprocessor with respect to conditional branching instructions, the reorder buffer includes a flag storage area for storing flags that are updated by flag modifying instructions. The flags are renamed to make possible the earlier execution of branch instructions which depend on flag modifying instructions. If a flag is not yet determined, then a flag tag is associated with the flag storage area in place of that flag until the actual flag value is determined. A flag operand bus and a flag tag bus are provided between the flag storage area and the branching functional unit so that the requested flag or flag tags are provided to instructions which are executed in the branching functional unit.
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