NullnessFrame

The set of aliased values for a given entry in the values array.

When entering an exception handler, all values are dropped from the stack (and the exception value is pushed). The ASM analyzer invokes firstHandlerInstructionFrame.clearStack(). To ensure consistent aliasing sets, we need to remove the dropped values from aliasing sets.

Merge the AliasingFrame other into this AliasingFrame.

Aliases that are common in both frames are kept. Example:

var x, y = null if (...) { x = a y = a // (x, y, a) are aliases } else { x = a y = b // (x, a) and (y, b) } [...] // (x, a) -- merge of ((x, y, a)) and ((x, a), (y, b))

Returns a string representation of the object.

The default representation is platform dependent.

For every value the set of values that are aliases of it.

Invariants:

• If aliases(i) == null then i has no aliases. This is equivalent to having aliases(i) == SingletonSet(i).
• If aliases(i) != null then aliases(i) contains i.
• If aliases(i) contains j then aliases(i) eq aliases(j), i.e., they are references to the same (mutable) AliasSet.