8.6. Predication Based on Floating-Point Values
Comparisons between pairs of data values lie close to the heart of truly useful CPU operations from a programmer's perspective, as we said in Chapter 5. The outcome of a comparison is a Boolean true or false condition that directs the selective execution of portions of an algorithm that require choices, or branching.
We saw that there is a close relationship between comparisons and the concept called predication. The Itanium architecture implements predication by storing the Boolean result of a comparison in a pair of predicate registers. In general, the first predicate register is set to 1 and the other to 0; the logically opposite outcome would instead set the first to 0 and the second to 1. In ...
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