These are stratified sets, as described in "Fast algorithms for
Dyck-CFL-reachability with applications to Alias Analysis" by Zhang Q, Lyu M R, Yuan H, and Su Z.
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template<typename
T>
class llvm::cflaa::StratifiedSets< T >
These are stratified sets, as described in "Fast algorithms for
Dyck-CFL-reachability with applications to Alias Analysis" by Zhang Q, Lyu M R, Yuan H, and Su Z.
– in short, this is meant to represent different sets of Value*s. If two Value*s are in the same set, or if both sets have overlapping attributes, then the Value*s are said to alias.
Sets may be related by position, meaning that one set may be considered as above or below another. In CFL Alias Analysis, this gives us an indication of how two variables are related; if the set of variable A is below a set containing variable B, then at some point, a variable that has interacted with B (or B itself) was either used in order to extract the variable A, or was used as storage of variable A.
Sets may also have attributes (as noted above). These attributes are generally used for noting whether a variable in the set has interacted with a variable whose origins we don't quite know (i.e. globals/arguments), or if the variable may have had operations performed on it (modified in a function call). All attributes that exist in a set A must exist in all sets marked as below set A.
Definition at line 83 of file StratifiedSets.h.