Package com.oracle.truffle.api.dsl

Annotation Interface Bind

@Retention(CLASS)
@Target(PARAMETER)
public @interface Bind

Binds and executes an expression at most once for every execution of the node. This is useful if an expression cannot be repeated safely for a guard and its associated specialization method. For example, if a read of a field is volatile two consecutive reads might not lead to the same result. The name the extract parameter can be referred to in cached, guard, limit, assumption expressions or the specialization body. The bind expression may refer to dynamic parameters, previously declared bind or cached parameters and node field declarations.

If a bind parameter only uses cached values, then it is considered also a cached value. If the parameter uses any dynamic parameter then the extract parameter is considered also a dynamic parameter.

Usage examples:

 static class DynamicObject {

     volatile Object storage;

     DynamicObject(Object storage) {
         this.storage = storage;
     }
 }

 abstract static class ExtractStorageNode extends Node {

     abstract Object execute(Object arg0);

     @Specialization(guards = "storage == cachedStorage", limit = "3")
     Object s0(DynamicObject a0,
                     @Bind("a0.storage") Object storage,
                     @Cached("storage") Object cachedStorage) {
         // use storage in specialization and in guard.
         return a0;
     }
 }
 

The special variable $node can be used to bind the current node. Bytecode DSL interpreters can also bind the special variables $rootNode, $bytecodeNode, and $bytecodeIndex.

Since:

20.2

See Also:

• Cached
• Specialization

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static @interface	Bind.DefaultExpression	Defines a default bind expression for a given type.

Optional Element Summary

Optional Elements

Modifier and Type	Optional Element	Description
String	value	The extract expression.

Element Details

value

String value

The extract expression.

Since:

20.2

See Also:

• Bind

Default:

""