Matching and Scoring Context Selectors

| OPENMP API Specification: "Version 5.2 -- GIT rev 95b2e3a44"

A given context selector is compatible with a given OpenMP context if the following conditions are satisﬁed:

All selectors in the user set of the context selector are true;
All traits and trait properties that are deﬁned by selectors in the target_device set of the context selector are active in the target_device trait set for the device that is identiﬁed by the device_num selector;
All traits and trait properties that are deﬁned by selectors in the construct, device and implementation sets of the context selector are active in the corresponding trait sets of the OpenMP context;
For each selector in the context selector, its properties are a subset of the properties of the corresponding trait of the OpenMP context;
Selectors in the construct set of the context selector appear in the same relative order as their corresponding traits in the construct trait set of the OpenMP context; and
No speciﬁed implementation-deﬁned selector is ignored by the implementation.

Some properties of the simd selector have special rules to match the properties of the simd trait:

The simdlen(N) property of the selector matches the simdlen(M) trait of the OpenMP context if M is a multiple of N; and
The aligned(list:N) property of the selector matches the aligned(list:M) trait of the OpenMP context if N is a multiple of M.

Among compatible context selectors, a score is computed using the following algorithm:

1.: Each trait selector for which the corresponding trait appears in the construct trait set in the OpenMP context is given the value 2^p−1 where p is the position of the corresponding trait, c_p, in the context construct trait set; if the traits that correspond to the construct selector set appear multiple times in the OpenMP context, the highest valued subset of context traits that contains all selectors in the same order are used;
2.: The kind, arch, and isa selectors, if speciﬁed, are given the values 2^l, 2^l+1 and 2^l+2, respectively, where l is the number of traits in the construct set;
3.: Trait selectors for which a trait-score is speciﬁed are given the value speciﬁed by the trait-score score-expression;
4.: The values given to any additional selectors allowed by the implementation are implementation deﬁned;
5.: Other selectors are given a value of zero; and
6.: A context selector that is a strict subset of another context selector has a score of zero. For other context selectors, the ﬁnal score is the sum of the values of all speciﬁed selectors plus 1.