Re: Ada case-statement

["J-P. Rosen" <rosen@adalog.fr>]

Le 15/03/2018 à 04:10, Dan'l Miller a écrit :
> For dense case statements that utilize all or most of an enumerated
> type's enumerated values, a jump table is the most likely on most
> processors to achieve O(1) growth [instead of if-statement-based O(n)
> growth, where n is the quantity of enumerated values in an enumerated
> type].
Long time ago, as I was working on Ada/ED, my shelf had a PHD thesis
entirely on how to generate code for case statements. Various techniques
depending on the number of values, the density of mentionned values in
the subtype, etc.

Of course, you had the if/elsif and plain jump table techniques, but
also hashed jump tables, jump tables indexed by intervals, various mixes
(if/elsif to eliminate sparse cases, then tables for the rest)...

-- 
J-P. Rosen
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