Invention Grant
US08504805B2 Processor operating mode for mitigating dependency conditions between instructions having different operand sizes 有权
用于缓解具有不同操作数大小的指令之间的依赖条件的处理器操作模式

Processor operating mode for mitigating dependency conditions between instructions having different operand sizes
Abstract:
Various techniques for mitigating dependencies between groups of instructions are disclosed. In one embodiment, such dependencies include “evil twin” conditions, in which a first floating-point instruction has as a destination a first portion of a logical floating-point register (e.g., a single-precision write), and in which a second, subsequent floating-point instruction has as a source the first portion and a second portion of the same logical floating-point register (e.g., a double-precision read). The disclosed techniques may be applicable in a multithreaded processor implementing register renaming. In one embodiment, a processor may enter an operating mode in which detection of evil twin “producers” (e.g., single-precision writes) causes the instruction sequence to be modified to break potential dependencies. Modification of the instruction sequence may continue until one or more exit criteria are reached (e.g., committing a predetermined number of single-precision writes). This operating mode may be employed on a per-thread basis.
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