Predication (computer architecture): Difference between revisions

Revision as of 21:04, 7 June 2021

Revision as of 21:05, 7 June 2021

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}}</ref> The instructions from the taken path are permitted to modify architectural state because they have been associated (''predicated'') with a ''predicate'', a [[Boolean data type|Boolean value]] used by the instruction to control whether the instruction is allowed to modify the architectural state or not.

Put simply: if the Register Condition bit is set, the instruction is executed:; if the bit is clear, it is not. With Condition Register's contents being dynamic, thepredicated instruction execution is likewise dynamic, i.e. (conditionally) determined at runtime.

[[Vector processors]], some [[SIMD]] ISAs (such as [[AVX2]] and [[AVX-512]]]) and [[GPU]]s in general make heavy use of predication, applying one bit of a conditional ''mask Vector'' to the corresponding elements in the Vector registers being processed, where scalar predication in scalar instruction sets only need the one predicate bit.