Predication (computer architecture): Difference between revisions

Revision as of 12:57, 22 October 2022

Revision as of 22:14, 24 November 2022

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==Disadvantages==

Predication's primary drawback is in increased encoding space. In typical implementations, every instruction reserves a bitfield for the predicate specifying under what conditions that instruction should have an effect. When available memory is limited, as on [[embedded system|embedded devices]], this space cost can be prohibitive. However, some architectures such as [[Thumb-2]] are able to avoid this issue (see below). Other detriments are the following:<ref name="Fisher04">{{cite book |firstfirst1=Joseph A. |lastlast1=Fisher |first2=Paolo |last2=Faraboschi |first3=Cliff |last3=Young |year=2004 |title=Embedded Computing — A VLIW Approach to Architecture, Compilers, and Tools |page=172 |chapter-url=https://www.google.com/books/edition/Embedded_Computing/DbOa0p1wRD4C?hl=en&gbpv=1&pg=PA172 |chapter=4.5.2 Predication § Predication in the Embedded Domain |isbn=9780080477541 |publisher=Elsevier}}</ref>

*Predication complicates the hardware by adding levels of [[control unit|logic]] to critical [[datapath|paths]] and potentially degrades clock speed.

*A predicated block includes cycles for all operations, so shorter [[control-flow graph|paths]] may take longer and be penalized.

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==Further reading==

*{{cite book|first=Alan |last=Clements|title=Computer Organization & Architecture: Themes and Variations |chapter=8.3.7 Predication |chapter-url={{google books|id=ySILAAAAQBAJ&pg=PA532|plainurl=yes}}|year=2013|publisher=Cengage Learning|isbn=978-1-285-41542-60|pages=532–9}}

{{DEFAULTSORT:Predication}}