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package com.oracle.truffle.sl.nodes.call;
import com.oracle.truffle.api.Assumption;
import com.oracle.truffle.api.CallTarget;
import com.oracle.truffle.api.RootCallTarget;
import com.oracle.truffle.api.dsl.Cached;
import com.oracle.truffle.api.dsl.Fallback;
import com.oracle.truffle.api.dsl.Specialization;
import com.oracle.truffle.api.dsl.TypeSystemReference;
import com.oracle.truffle.api.interop.ArityException;
import com.oracle.truffle.api.interop.ForeignAccess;
import com.oracle.truffle.api.interop.Message;
import com.oracle.truffle.api.interop.TruffleObject;
import com.oracle.truffle.api.interop.UnsupportedMessageException;
import com.oracle.truffle.api.interop.UnsupportedTypeException;
import com.oracle.truffle.api.nodes.DirectCallNode;
import com.oracle.truffle.api.nodes.IndirectCallNode;
import com.oracle.truffle.api.nodes.Node;
import com.oracle.truffle.sl.nodes.SLTypes;
import com.oracle.truffle.sl.nodes.interop.SLForeignToSLTypeNode;
import com.oracle.truffle.sl.nodes.interop.SLForeignToSLTypeNodeGen;
import com.oracle.truffle.sl.runtime.SLFunction;
import com.oracle.truffle.sl.runtime.SLUndefinedNameException;
@TypeSystemReference(SLTypes.class)
public abstract class SLDispatchNode extends Node {
protected static final int INLINE_CACHE_SIZE = 2;
public abstract Object executeDispatch(Object function, Object[] arguments);
/**
* Inline cached specialization of the dispatch.
*
* <p>
* Since SL is a quite simple language, the benefit of the inline cache seems small: after
* checking that the actual function to be executed is the same as the cachedFuntion, we can
* safely execute the cached call target. You can reasonably argue that caching the call target
* is overkill, since we could just retrieve it via {@code function.getCallTarget()}. However,
* caching the call target and using a {@link DirectCallNode} allows Truffle to perform method
* inlining. In addition, in a more complex language the lookup of the call target is usually
* much more complicated than in SL.
* </p>
*
* <p>
* {@code limit = "INLINE_CACHE_SIZE"} Specifies the limit number of inline cache specialization
* instantiations.
* </p>
* <p>
* {@code guards = "function.getCallTarget() == cachedTarget"} The inline cache check. Note that
* cachedTarget is a final field so that the compiler can optimize the check.
* </p>
* <p>
* {@code assumptions = "callTargetStable"} Support for function redefinition: When a function
* is redefined, the call target maintained by the SLFunction object is changed. To avoid a
* check for that, we use an Assumption that is invalidated by the SLFunction when the change is
* performed. Since checking an assumption is a no-op in compiled code, the assumption check
* performed by the DSL does not add any overhead during optimized execution.
* </p>
*
* @see Cached
* @see Specialization
*
* @param function the dynamically provided function
* @param cachedFunction the cached function of the specialization instance
* @param callNode the {@link DirectCallNode} specifically created for the {@link CallTarget} in
* cachedFunction.
*/
@Specialization(limit = "INLINE_CACHE_SIZE", //
guards = "function.getCallTarget() == cachedTarget", //
assumptions = "callTargetStable")
@SuppressWarnings("unused")
protected static Object doDirect(SLFunction function, Object[] arguments,
@Cached("function.getCallTargetStable()") Assumption callTargetStable,
@Cached("function.getCallTarget()") RootCallTarget cachedTarget,
@Cached("create(cachedTarget)") DirectCallNode callNode) {
/* Inline cache hit, we are safe to execute the cached call target. */
return callNode.call(arguments);
}
/**
* Slow-path code for a call, used when the polymorphic inline cache exceeded its maximum size
* specified in <code>INLINE_CACHE_SIZE</code>. Such calls are not optimized any further, e.g.,
* no method inlining is performed.
*/
@Specialization(replaces = "doDirect")
protected static Object doIndirect(SLFunction function, Object[] arguments,
@Cached("create()") IndirectCallNode callNode) {
/*
* SL has a quite simple call lookup: just ask the function for the current call target, and
* call it.
*/
return callNode.call(function.getCallTarget(), arguments);
}
/**
* When no specialization fits, the receiver is not an object (which is a type error).
*/
@Fallback
protected static Object unknownFunction(Object function, @SuppressWarnings("unused") Object[] arguments) {
throw SLUndefinedNameException.undefinedFunction(function);
}
/**
* Language interoperability: If the function is a foreign value, i.e., not a SLFunction, we use
* Truffle's interop API to execute the foreign function.
*/
@Specialization(guards = "isForeignFunction(function)")
protected static Object doForeign(TruffleObject function, Object[] arguments,
// The child node to call the foreign function
@Cached("createCrossLanguageCallNode(arguments)") Node crossLanguageCallNode,
// The child node to convert the result of the foreign call to a SL value
@Cached("createToSLTypeNode()") SLForeignToSLTypeNode toSLTypeNode) {
try {
/* Perform the foreign function call. */
Object res = ForeignAccess.sendExecute(crossLanguageCallNode, function, arguments);
/* Convert the result to a SL value. */
return toSLTypeNode.executeConvert(res);
} catch (ArityException | UnsupportedTypeException | UnsupportedMessageException e) {
/* Foreign access was not successful. */
throw SLUndefinedNameException.undefinedFunction(function);
}
}
protected static boolean isForeignFunction(TruffleObject function) {
return !(function instanceof SLFunction);
}
protected static Node createCrossLanguageCallNode(Object[] arguments) {
return Message.createExecute(arguments.length).createNode();
}
protected static SLForeignToSLTypeNode createToSLTypeNode() {
return SLForeignToSLTypeNodeGen.create();
}
}