Package com.oracle.truffle.api
Interface Assumption
- All Known Implementing Classes:
AbstractAssumption
,AlwaysValidAssumption
,NeverValidAssumption
,UnionAssumption
public interface Assumption
An assumption is a global boolean flag that starts with the value true (i.e., the assumption is
valid) and can subsequently be invalidated (using
invalidate()
). Once
invalidated, an assumption can never get valid again. Assumptions can be created using the
TruffleRuntime.createAssumption()
or the TruffleRuntime.createAssumption(String)
method. The Truffle compiler has special knowledge of this class in order to produce efficient
machine code for checking an assumption in case the assumption object is a compile time constant.
Therefore, assumptions should be stored in final fields in Truffle nodes.
All instances of classes implementing Assumption
must be held in final
fields for
compiler optimizations to take effect.-
Method Details
-
check
Checks that this assumption is still valid. The method throws an exception, if this is no longer the case. This method is preferred over theisValid()
method when writing guest language interpreter code. The catch block should perform a node rewrite (seeNode.replace(Node)
) with a node that no longer relies on the assumption.- Throws:
InvalidAssumptionException
- If the assumption is no longer valid.
-
isValid
boolean isValid()Checks whether the assumption is still valid.- Returns:
- a boolean value indicating the validity of the assumption
-
invalidate
void invalidate()Invalidates this assumption. Performs no operation, if the assumption is already invalid. -
getName
String getName()A name for the assumption that is used for debug output.- Returns:
- the name of the assumption
-