Package com.oracle.truffle.api.dsl

Annotation Interface GenerateUncached

@Retention(CLASS)
@Target(TYPE)
public @interface GenerateUncached

Generates an uncached version of a node with specializations. Uncached versions of nodes don't specialize and don't use any profiling state. This allows to store them statically and to use them whenever no specialization/profiling is desired. The uncached version of the node is accessible using a static method called getUncached() on the generated node. GenerateUncached is inherited to subclasses if inherit() is set to true (default false).

The generated code for the uncached version is based on the specialization closure. The specialization closure only includes specializations that were are not replaced by others. This, for example, automatically excludes inline caches from the closure. Uses of the Cached annotation will automatically use getUncached instead of a cached version to initialize the cache.

A node subclass must fullfill the following requirements in order to be uncachable:

• At least one specialization and one execute method must be specified.
• The node has no instance fields.
• All Cached parameters provide valid uncached initializers.
• All specializations of the closure must not use rewriteOn attribute.
• All guards/cache/limit expressions must not bind the node receiver.

If any of these requirements are violated then an error will be shown. If node uses the NodeChild or NodeField annotations then they will return constant null or the primitive equivalent for the uncached node.

Example:

 @GenerateUncached
 abstract static class UncachableNode extends Node {

     abstract Object execute(Object arg);

     @Specialization(guards = "v == cachedV")
     static Object doCached(int v, @Cached("v") int cachedV) {
         // do cached
     }

     @Specialization(replaces = "doCached")
     static String doGeneric(int v) {
         // do uncached
     }

 }
 

This node produces the following uncached version of the execute method:

 @Override
 Object execute(Object arg0Value) {
     if (arg0Value instanceof Integer) {
         int arg0Value_ = (int) arg0Value;
         return UncachableNode.doGeneric(arg0Value_);
     }
     throw new UnsupportedSpecializationException(this, new Node[]{null}, arg0Value);
 }
 

Since:

19.0

See Also:

• Cached

Optional Element Summary

Optional Elements

Modifier and Type	Optional Element	Description
boolean	inherit	Inherits the semantics of the annotation to subclasses.
boolean	value	If true enables the generation of an uncached version of this specializing node.

Element Details

value

boolean value

If true enables the generation of an uncached version of this specializing node. It is disabled by default.

Since:

19.0

Default:

true

inherit

boolean inherit

Inherits the semantics of the annotation to subclasses.

Since:

19.1.0

Default:

false