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package com.oracle.svm.core.heap;

import org.graalvm.nativeimage.Platform;
import org.graalvm.nativeimage.Platforms;

import com.oracle.svm.core.code.CodeInfo;
import com.oracle.svm.core.code.CodeInfoAccess;
import com.oracle.svm.core.code.CodeInfoTable;
import com.oracle.svm.core.code.RuntimeCodeCache.CodeInfoVisitor;
import com.oracle.svm.core.graal.meta.SharedRuntimeMethod;

import jdk.vm.ci.meta.SpeculationLog.SpeculationReason;

import com.oracle.svm.core.code.RuntimeCodeInfoAccess;
import com.oracle.svm.core.code.RuntimeCodeInfoMemory;

Cleans the code cache and frees the unmanaged memory that is used by CodeInfo objects. Furthermore, it also actively invalidates and frees code that has references to otherwise no longer reachable Java heap objects. /**
 * Cleans the code cache and frees the unmanaged memory that is used by {@link CodeInfo} objects.
 * Furthermore, it also actively invalidates and frees code that has references to otherwise no
 * longer reachable Java heap objects.
 */
public final class RuntimeCodeCacheCleaner implements CodeInfoVisitor {
    
To avoid unnecessary deoptimizations, we need to assume that objects of the following classes
are reachable, even if they don't have any strong references:

SpeculationReason objects are embedded in the code and only needed when a deoptimization is triggered.
SharedRuntimeMethod objects are sometimes used as artifical methods (e.g., for adapter code) and are located in the frame info object constants.

/**
     * To avoid unnecessary deoptimizations, we need to assume that objects of the following classes
     * are reachable, even if they don't have any strong references:
     * <ul>
     * <li>{@link SpeculationReason} objects are embedded in the code and only needed when a
     * deoptimization is triggered.</li>
     * <li>{@link SharedRuntimeMethod} objects are sometimes used as artifical methods (e.g., for
     * adapter code) and are located in the frame info object constants.</li>
     * </ul>
     */
    public static final Class<?>[] CLASSES_ASSUMED_REACHABLE = {SpeculationReason.class, SharedRuntimeMethod.class};

    @Platforms(Platform.HOSTED_ONLY.class)
    public RuntimeCodeCacheCleaner() {
    }

    @Override
    public <T extends CodeInfo> boolean visitCode(T codeInfo) {
        if (RuntimeCodeInfoAccess.areAllObjectsOnImageHeap(codeInfo)) {
            return true;
        }

        int state = CodeInfoAccess.getState(codeInfo);
        if (state == CodeInfo.STATE_UNREACHABLE) {
            freeMemory(codeInfo);
        } else if (state == CodeInfo.STATE_READY_FOR_INVALIDATION) {
            // All objects that are accessed during invalidation must still be reachable.
            CodeInfoTable.invalidateNonStackCodeAtSafepoint(codeInfo);
            assert CodeInfoAccess.getState(codeInfo) == CodeInfo.STATE_PARTIALLY_FREED;
            freeMemory(codeInfo);
        }
        return true;
    }

    private static void freeMemory(CodeInfo codeInfo) {
        boolean removed = RuntimeCodeInfoMemory.singleton().removeDuringGC(codeInfo);
        assert removed : "must have been present";
        RuntimeCodeInfoAccess.releaseMethodInfoMemory(codeInfo, false);
    }
}