diff --git a/tycho-core/src/main/java/org/eclipse/tycho/p2tools/copiedfromp2/PermissiveSlicer.java b/tycho-core/src/main/java/org/eclipse/tycho/p2tools/copiedfromp2/PermissiveSlicer.java
new file mode 100644
index 0000000000..efd12d0ead
--- /dev/null
+++ b/tycho-core/src/main/java/org/eclipse/tycho/p2tools/copiedfromp2/PermissiveSlicer.java
@@ -0,0 +1,74 @@
+/*******************************************************************************
+ * Copyright (c) 2009, 2017 IBM Corporation and others.
+ *
+ * This
+ * program and the accompanying materials are made available under the terms of
+ * the Eclipse Public License 2.0 which accompanies this distribution, and is
+ * available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors: IBM Corporation - initial API and implementation
+ ******************************************************************************/
+package org.eclipse.tycho.p2tools.copiedfromp2;
+
+import java.util.Map;
+
+import org.eclipse.equinox.internal.p2.director.Slicer;
+import org.eclipse.equinox.internal.p2.metadata.RequiredCapability;
+import org.eclipse.equinox.p2.metadata.IInstallableUnit;
+import org.eclipse.equinox.p2.metadata.IRequirement;
+import org.eclipse.equinox.p2.metadata.expression.IMatchExpression;
+import org.eclipse.equinox.p2.query.IQueryable;
+
+public class PermissiveSlicer extends Slicer {
+    private boolean includeOptionalDependencies; //Cause optional dependencies not be followed as part of the
+    private boolean everythingGreedy;
+    private boolean considerFilter;
+    private boolean considerOnlyStrictDependency;
+    private boolean evalFilterTo;
+    private boolean onlyFilteredRequirements;
+
+    public PermissiveSlicer(IQueryable<IInstallableUnit> input, Map<String, String> context,
+            boolean includeOptionalDependencies, boolean everythingGreedy, boolean evalFilterTo,
+            boolean considerOnlyStrictDependency, boolean onlyFilteredRequirements) {
+        super(input, context, true);
+        this.considerFilter = context != null && context.size() > 1;
+        this.includeOptionalDependencies = includeOptionalDependencies;
+        this.everythingGreedy = everythingGreedy;
+        this.evalFilterTo = evalFilterTo;
+        this.considerOnlyStrictDependency = considerOnlyStrictDependency;
+        this.onlyFilteredRequirements = onlyFilteredRequirements;
+    }
+
+    @Override
+    protected boolean isApplicable(IInstallableUnit iu) {
+        if (considerFilter) {
+            return super.isApplicable(iu);
+        }
+        return iu.getFilter() == null || evalFilterTo;
+    }
+
+    @Override
+    protected boolean isApplicable(IRequirement req) {
+        //Every filter in this method needs to continue except when the filter does not pass
+        if (!includeOptionalDependencies && req.getMin() == 0) {
+            return false;
+        }
+        if (considerOnlyStrictDependency && !RequiredCapability.isStrictVersionRequirement(req.getMatches())) {
+            return false;
+        }
+        //deal with filters
+        IMatchExpression<IInstallableUnit> filter = req.getFilter();
+        if (filter == null) {
+            return !onlyFilteredRequirements;
+        }
+        return considerFilter ? filter.isMatch(selectionContext) : evalFilterTo;
+    }
+
+    @Override
+    protected boolean isGreedy(IRequirement req) {
+        return everythingGreedy || super.isGreedy(req);
+    }
+}
diff --git a/tycho-core/src/main/java/org/eclipse/tycho/p2tools/copiedfromp2/Slicer.java b/tycho-core/src/main/java/org/eclipse/tycho/p2tools/copiedfromp2/Slicer.java
new file mode 100644
index 0000000000..db43457c8a
--- /dev/null
+++ b/tycho-core/src/main/java/org/eclipse/tycho/p2tools/copiedfromp2/Slicer.java
@@ -0,0 +1,239 @@
+/*******************************************************************************
+ *  Copyright (c) 2007, 2022 IBM Corporation and others.
+ *
+ *  This program and the accompanying materials
+ *  are made available under the terms of the Eclipse Public License 2.0
+ *  which accompanies this distribution, and is available at
+ *  https://www.eclipse.org/legal/epl-2.0/
+ *
+ *  SPDX-License-Identifier: EPL-2.0
+ *
+ *  Contributors:
+ *      IBM Corporation - initial API and implementation
+ *      Sonatype, Inc. - ongoing development
+ *      Christoph Läubrich - Issue #39 - Slicer should allow filtering of a requirement based on the IU currently processed
+ *******************************************************************************/
+package org.eclipse.tycho.p2tools.copiedfromp2;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Map;
+import java.util.Queue;
+import java.util.Set;
+
+import org.eclipse.core.runtime.IProgressMonitor;
+import org.eclipse.core.runtime.IStatus;
+import org.eclipse.core.runtime.MultiStatus;
+import org.eclipse.core.runtime.NullProgressMonitor;
+import org.eclipse.core.runtime.OperationCanceledException;
+import org.eclipse.core.runtime.Status;
+import org.eclipse.equinox.internal.p2.core.helpers.LogHelper;
+import org.eclipse.equinox.internal.p2.core.helpers.Tracing;
+import org.eclipse.equinox.internal.p2.director.Messages;
+import org.eclipse.equinox.internal.p2.director.QueryableArray;
+import org.eclipse.equinox.internal.p2.metadata.InstallableUnit;
+import org.eclipse.equinox.internal.p2.metadata.InstallableUnitPatch;
+import org.eclipse.equinox.p2.metadata.IInstallableUnit;
+import org.eclipse.equinox.p2.metadata.IInstallableUnitFragment;
+import org.eclipse.equinox.p2.metadata.IInstallableUnitPatch;
+import org.eclipse.equinox.p2.metadata.IRequirement;
+import org.eclipse.equinox.p2.metadata.IRequirementChange;
+import org.eclipse.equinox.p2.metadata.Version;
+import org.eclipse.equinox.p2.metadata.expression.IMatchExpression;
+import org.eclipse.equinox.p2.query.IQueryResult;
+import org.eclipse.equinox.p2.query.IQueryable;
+import org.eclipse.equinox.p2.query.QueryUtil;
+import org.eclipse.osgi.util.NLS;
+
+public class Slicer {
+    private static boolean DEBUG = false;
+    private final IQueryable<IInstallableUnit> possibilites;
+    private final boolean considerMetaRequirements;
+    protected final IInstallableUnit selectionContext;
+    /** The IUs that have been considered to be part of the problem */
+    private final Map<String, Map<Version, IInstallableUnit>> slice = new HashMap<>();
+    private final MultiStatus result = new MultiStatus(Slicer.class, 0, Messages.Planner_Problems_resolving_plan);
+
+    private Queue<IInstallableUnit> toProcess;
+    private Set<IInstallableUnit> considered; // IUs to add to the slice
+    private final Set<IInstallableUnit> nonGreedyIUs = new HashSet<>(); // IUs that are brought in by non greedy dependencies
+
+    public Slicer(IQueryable<IInstallableUnit> input, Map<String, String> context, boolean considerMetaRequirements) {
+        this(input, InstallableUnit.contextIU(context), considerMetaRequirements);
+    }
+
+    public Slicer(IQueryable<IInstallableUnit> possibilites, IInstallableUnit selectionContext,
+            boolean considerMetaRequirements) {
+        this.possibilites = possibilites;
+        this.selectionContext = selectionContext;
+        this.considerMetaRequirements = considerMetaRequirements;
+    }
+
+    public IQueryable<IInstallableUnit> slice(Collection<IInstallableUnit> ius, IProgressMonitor monitor) {
+        monitor = IProgressMonitor.nullSafe(monitor);
+        try {
+            long start = 0;
+            if (DEBUG) {
+                start = System.currentTimeMillis();
+                System.out.println("Start slicing: " + start); //$NON-NLS-1$
+            }
+            validateInput(ius);
+            considered = new HashSet<>(ius);
+            toProcess = new LinkedList<>(considered);
+            while (!toProcess.isEmpty()) {
+                if (monitor.isCanceled()) {
+                    result.merge(Status.CANCEL_STATUS);
+                    throw new OperationCanceledException();
+                }
+                processIU(toProcess.remove());
+            }
+            computeNonGreedyIUs();
+            if (DEBUG) {
+                long stop = System.currentTimeMillis();
+                System.out.println("Slicing complete: " + (stop - start)); //$NON-NLS-1$
+            }
+        } catch (IllegalStateException e) {
+            result.add(Status.error(e.getMessage(), e));
+        }
+        if (Tracing.DEBUG && result.getSeverity() != IStatus.OK) {
+            LogHelper.log(result);
+        }
+        if (result.getSeverity() == IStatus.ERROR) {
+            return null;
+        }
+        return new QueryableArray(considered);
+    }
+
+    private void computeNonGreedyIUs() {
+        IQueryable<IInstallableUnit> queryable = new QueryableArray(considered);
+        for (IInstallableUnit iu : queryable.query(QueryUtil.ALL_UNITS, new NullProgressMonitor())) {
+            iu = iu.unresolved();
+            Collection<IRequirement> reqs = getRequirements(iu);
+            for (IRequirement req : reqs) {
+                if (!isApplicable(iu, req)) {
+                    continue;
+                }
+                if (!isGreedy(iu, req)) {
+                    nonGreedyIUs.addAll(
+                            queryable.query(QueryUtil.createMatchQuery(req.getMatches()), null).toUnmodifiableSet());
+                }
+            }
+        }
+    }
+
+    public MultiStatus getStatus() {
+        return result;
+    }
+
+    // This is a shortcut to simplify the error reporting when the filter of the ius
+    // we are being asked to install does not pass
+    private void validateInput(Collection<IInstallableUnit> ius) {
+        for (IInstallableUnit iu : ius) {
+            if (!isApplicable(iu)) {
+                throw new IllegalStateException(NLS.bind(Messages.Explanation_missingRootFilter, iu));
+            }
+        }
+    }
+
+    // Check whether the requirement is applicable
+
+    protected boolean isApplicable(IInstallableUnit unit, IRequirement req) {
+        return isApplicable(req);
+    }
+
+    protected boolean isApplicable(IRequirement req) {
+        IMatchExpression<IInstallableUnit> filter = req.getFilter();
+        return filter == null || filter.isMatch(selectionContext);
+    }
+
+    protected boolean isApplicable(IInstallableUnit iu) {
+        IMatchExpression<IInstallableUnit> filter = iu.getFilter();
+        return filter == null || filter.isMatch(selectionContext);
+    }
+
+    protected void processIU(IInstallableUnit iu) {
+        iu = iu.unresolved();
+        Map<Version, IInstallableUnit> iuSlice = slice.computeIfAbsent(iu.getId(), i -> new HashMap<>());
+        iuSlice.put(iu.getVersion(), iu);
+        if (!isApplicable(iu)) {
+            return;
+        }
+        Collection<IRequirement> reqs = getRequirements(iu);
+        for (IRequirement req : reqs) {
+            if (isApplicable(iu, req) && isGreedy(iu, req)) {
+                expandRequirement(iu, req);
+            }
+        }
+    }
+
+    protected boolean isGreedy(IInstallableUnit unit, IRequirement req) {
+        return isGreedy(req);
+    }
+
+    protected boolean isGreedy(IRequirement req) {
+        return req.isGreedy();
+    }
+
+    private Collection<IRequirement> getRequirements(IInstallableUnit iu) {
+        boolean isPatch = iu instanceof IInstallableUnitPatch;
+        boolean isFragment = iu instanceof IInstallableUnitFragment;
+        // Short-circuit for the case of an IInstallableUnit
+        if (!isFragment && !isPatch && iu.getMetaRequirements().isEmpty()) {
+            return iu.getRequirements();
+        }
+
+        List<IRequirement> aggregatedRequirements = new ArrayList<>(iu.getRequirements().size()
+                + iu.getMetaRequirements().size() + (isFragment ? ((IInstallableUnitFragment) iu).getHost().size() : 0)
+                + (isPatch ? ((IInstallableUnitPatch) iu).getRequirementsChange().size() : 0));
+        aggregatedRequirements.addAll(iu.getRequirements());
+
+        if (iu instanceof IInstallableUnitFragment iuFragment) {
+            aggregatedRequirements.addAll(iuFragment.getHost());
+        }
+        if (iu instanceof InstallableUnitPatch patchIU) {
+            List<IRequirementChange> changes = patchIU.getRequirementsChange();
+            for (IRequirementChange change : changes) {
+                aggregatedRequirements.add(change.newValue());
+            }
+        }
+        if (considerMetaRequirements) {
+            aggregatedRequirements.addAll(iu.getMetaRequirements());
+        }
+        return aggregatedRequirements;
+    }
+
+    private void expandRequirement(IInstallableUnit iu, IRequirement req) {
+        if (req.getMax() == 0) {
+            return;
+        }
+        IQueryResult<IInstallableUnit> matches = possibilites.query(QueryUtil.createMatchQuery(req.getMatches()), null);
+        int validMatches = 0;
+        for (IInstallableUnit match : matches) {
+            if (!isApplicable(match)) {
+                continue;
+            }
+            validMatches++;
+            Map<Version, IInstallableUnit> iuSlice = slice.get(match.getId());
+            if ((iuSlice == null || !iuSlice.containsKey(match.getVersion())) && considered.add(match)) {
+                toProcess.add(match);
+            }
+        }
+        if (validMatches == 0) {
+            if (req.getMin() == 0) {
+                if (DEBUG) {
+                    System.out.println("No IU found to satisfy optional dependency of " + iu + " on req " + req); //$NON-NLS-1$//$NON-NLS-2$
+                }
+            } else {
+                result.add(Status.warning(NLS.bind(Messages.Planner_Unsatisfied_dependency, iu, req)));
+            }
+        }
+    }
+
+    Set<IInstallableUnit> getNonGreedyIUs() {
+        return nonGreedyIUs;
+    }
+}