Compilation and Optimization

/**
 * Optimized implementation of CallTarget that provides compilation 
 * and performance monitoring capabilities
 */
public abstract class OptimizedCallTarget implements CallTarget, ReplaceObserver {
    /** Executes the call target with given arguments */
    public final Object call(Object... arguments);
    
    /** Checks if this call target's compiled code is still valid */
    public abstract boolean isValid();
    
    /** Invalidates the compiled code, forcing recompilation */
    public abstract void invalidate();
    
    /** Invalidates with a specific reason for debugging */
    public abstract void invalidate(String reason);
    
    /** Returns the number of times this call target has been invoked */
    public abstract int getCallCount();
    
    /** Returns the time spent compiling this call target (in nanoseconds) */
    public abstract long getCompilationTime();
    
    /** Checks if this call target is currently being compiled */
    public abstract boolean isCompiling();
    
    /** Checks if this call target has been compiled */
    public abstract boolean isCompiled();
    
    /** Forces compilation of this call target */
    public abstract void compile();
    
    /** Returns compilation metadata and statistics */
    public abstract CompilationResult getCompilationResult();
    
    /** Returns the root node associated with this call target */
    public final RootNode getRootNode();
    
    /** Sets a custom name for this call target */
    public final void setName(String name);
    
    /** Returns the name of this call target */
    public final String getName();
}

import com.oracle.truffle.api.Truffle;
import com.oracle.truffle.api.nodes.RootNode;
import com.oracle.truffle.runtime.OptimizedCallTarget;

// Create an optimized call target
RootNode rootNode = new MyLanguageRootNode();
OptimizedCallTarget callTarget = (OptimizedCallTarget) Truffle.getRuntime()
    .createCallTarget(rootNode);

// Monitor compilation status
if (!callTarget.isCompiled()) {
    System.out.println("Call count: " + callTarget.getCallCount());
    
    // Force compilation if needed
    callTarget.compile();
}

// Check if optimizations are still valid
if (!callTarget.isValid()) {
    System.out.println("Call target was invalidated, will recompile");
}

/**
 * Compiler optimization directives and hints for the Graal compiler
 */
public final class CompilerDirectives {
    /** Forces transfer from compiled code to interpreter */
    public static void transferToInterpreter();
    
    /** Forces transfer to interpreter and invalidates compiled code */
    public static void transferToInterpreterAndInvalidate();
    
    /** Checks if currently executing in interpreter mode */
    public static boolean inInterpreter();
    
    /** Checks if currently executing in compiled code */
    public static boolean inCompiledCode();
    
    /** Hints that a value should be treated as compilation constant */
    public static boolean isCompilationConstant(Object value);
    
    /** Hints that a condition is likely to be true */
    public static boolean injectBranchProbability(double probability, boolean condition);
    
    /** Marks a code path as unlikely to be executed */
    public static void bailout(String reason);
    
    /** Ensures a value is not optimized away */
    public static <T> T blackhole(T value);
    
    /** Hints that a method call should be inlined */
    public static void ensureVirtualized(Object object);
    
    /** Hints that an exception path is slow */
    public static RuntimeException shouldNotReachHere();
    
    /** Hints that an exception path is slow with message */
    public static RuntimeException shouldNotReachHere(String message);
    
    /** Hints that an exception path is slow with cause */
    public static RuntimeException shouldNotReachHere(Throwable cause);
}

public class MyLanguageNode extends Node {
    
    @CompilerDirectives.CompilationFinal
    private int constantValue = 42;
    
    public Object execute(VirtualFrame frame) {
        if (CompilerDirectives.inInterpreter()) {
            // This code only runs in interpreter
            collectProfile();
        }
        
        // Provide branch probability hint
        if (CompilerDirectives.injectBranchProbability(0.9, isCommonCase())) {
            return fastPath();
        } else {
            // Unlikely path - may cause deoptimization
            CompilerDirectives.transferToInterpreterAndInvalidate();
            return slowPath();
        }
    }
}

/**
 * Optimized implementation of Assumption that enables aggressive 
 * compiler optimizations based on runtime assumptions
 */
public final class OptimizedAssumption implements Assumption {
    /** Checks if this assumption is still valid */
    public boolean isValid();
    
    /** Invalidates this assumption and all dependent compiled code */
    public void invalidate();
    
    /** Invalidates this assumption with a specific message */
    public void invalidate(String message);
    
    /** Returns the name of this assumption */
    public String getName();
    
    /** Checks the assumption and throws exception if invalid */
    public void check() throws InvalidAssumptionException;
    
    /** Checks if the assumption has been checked in compiled code */
    public boolean isValidAssumption();
}

import com.oracle.truffle.api.Assumption;
import com.oracle.truffle.api.Truffle;

public class ClassLayout {
    private final Assumption stableLayout;
    
    public ClassLayout() {
        this.stableLayout = Truffle.getRuntime()
            .createAssumption("Stable class layout");
    }
    
    public Object getProperty(String name) {
        try {
            // Check assumption before using cached layout
            stableLayout.check();
            return getCachedProperty(name);
        } catch (InvalidAssumptionException e) {
            // Layout changed, update cache
            updateLayout();
            return getProperty(name);
        }
    }
    
    public void addProperty(String name) {
        // Adding property invalidates layout assumption
        stableLayout.invalidate("Property added: " + name);
        updateLayout();
    }
}

/**
 * Result of a compilation attempt
 */
public interface CompilationResult {
    /** Returns the target that was compiled */
    OptimizedCallTarget getTarget();
    
    /** Checks if compilation was successful */
    boolean isSuccess();
    
    /** Returns the compilation failure reason if any */
    String getFailureReason();
    
    /** Returns compilation time in nanoseconds */
    long getTimeCompilationFinished();
    
    /** Returns the number of nodes in compiled code */
    int getNodeCount();
    
    /** Returns the size of generated code in bytes */
    int getCodeSize();
}

/**
 * Actions to take when compilation fails
 */
public enum CompilationFailureAction {
    /** Silently continue with interpreter */
    Silent,
    
    /** Print compilation failure to console */
    Print,
    
    /** Throw exception on compilation failure */
    Throw,
    
    /** Exit the VM on compilation failure */
    ExitVM,
    
    /** Perform detailed diagnostics */
    Diagnose
}

/**
 * Optimized loop node that supports OSR compilation
 */
public abstract class OptimizedLoopNode extends Node implements LoopNode {
    /** Executes the loop with given frame */
    public abstract void execute(VirtualFrame frame);
    
    /** Returns the repeating node inside this loop */
    public abstract RepeatingNode getRepeatingNode();
    
    /** Checks if OSR is enabled for this loop */
    public abstract boolean isOSREnabled();
    
    /** Returns OSR compilation metadata */
    public abstract OSRMetadata getOSRMetadata();
}

/**
 * OSR (On-Stack Replacement) optimized loop node
 */
public final class OptimizedOSRLoopNode extends OptimizedLoopNode {
    /** Creates a new OSR loop node */
    public static OptimizedOSRLoopNode create(RepeatingNode repeatingNode);
    
    /** Executes the loop with OSR support */
    public void execute(VirtualFrame frame);
    
    /** Forces OSR compilation */
    public void forceOSR();
    
    /** Returns the OSR call target */
    public CallTarget getOSRCallTarget();
}

// Creating an optimized loop
RepeatingNode repeatingNode = new MyRepeatingNode();
OptimizedLoopNode loopNode = OptimizedOSRLoopNode.create(repeatingNode);

// The runtime automatically handles OSR compilation
// when the loop runs for a long time

public interface Assumption {
    /** Checks if the assumption is still valid */
    boolean isValid();
    
    /** Invalidates the assumption */
    void invalidate();
    
    /** Invalidates the assumption with a message */
    void invalidate(String message);
    
    /** Returns the assumption name */
    String getName();
    
    /** Checks the assumption, throwing exception if invalid */
    void check() throws InvalidAssumptionException;
}

public final class InvalidAssumptionException extends SlowPathException {
    /** Creates exception for invalid assumption */
    public InvalidAssumptionException(Assumption assumption);
    
    /** Returns the invalidated assumption */
    public Assumption getAssumption();
}

public interface RepeatingNode extends Node.Child {
    /** Executes one iteration of the repeating node */
    boolean executeRepeating(VirtualFrame frame);
}

public interface LoopNode extends Node.Child {
    /** Executes the entire loop */
    void execute(VirtualFrame frame);
    
    /** Returns the repeating node */
    RepeatingNode getRepeatingNode();
}