diff --git a/build.gradle b/build.gradle
index 8eb9643..c6b7c03 100644
--- a/build.gradle
+++ b/build.gradle
@@ -75,6 +75,7 @@
 dependencies {
     compile 'net.sf.jopt-simple:jopt-simple:4.6'
     compile group: 'com.google.guava', name: 'guava', version: '19.0'
+    compile group: 'it.unimi.dsi', name: 'fastutil', version: '7.2.0'
     compile group: 'org.apache.commons', name: 'commons-compress', version: '1.12'
     compile group: 'org.ow2.asm', name: 'asm', version: '5.1'
     compile group: 'org.ow2.asm', name: 'asm-commons', version: '5.1'
diff --git a/src/main/java/com/android/tools/r8/dex/DexFileReader.java b/src/main/java/com/android/tools/r8/dex/DexFileReader.java
index a38d397..627d106 100644
--- a/src/main/java/com/android/tools/r8/dex/DexFileReader.java
+++ b/src/main/java/com/android/tools/r8/dex/DexFileReader.java
@@ -50,8 +50,8 @@
 import com.android.tools.r8.graph.DexValue.DexValueString;
 import com.android.tools.r8.graph.OffsetToObjectMapping;
 import com.android.tools.r8.logging.Log;
-import com.android.tools.r8.utils.IntHashMap;
-import com.android.tools.r8.utils.InternalResource;
+import it.unimi.dsi.fastutil.ints.Int2ObjectMap;
+import it.unimi.dsi.fastutil.ints.Int2ObjectOpenHashMap;
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.nio.ShortBuffer;
@@ -91,10 +91,10 @@
   private OffsetToObjectMapping indexedItems = new OffsetToObjectMapping();
 
   // Mapping from offset to code item;
-  private IntHashMap<DexCode> codes = new IntHashMap<>();
+  private Int2ObjectMap<DexCode> codes = new Int2ObjectOpenHashMap<>();
 
   // Mapping from offset to dex item;
-  private IntHashMap<Object> offsetMap = new IntHashMap<>();
+  private Int2ObjectMap<Object> offsetMap = new Int2ObjectOpenHashMap<>();
 
   // Factory to canonicalize certain dexitems.
   private final DexItemFactory dexItemFactory;
@@ -140,7 +140,9 @@
   }
 
   private DexTypeList typeListAt(int offset) {
-    if (offset == 0) return DexTypeList.empty();
+    if (offset == 0) {
+      return DexTypeList.empty();
+    }
     return (DexTypeList) cacheAt(offset, this::parseTypeList);
   }
 
@@ -358,9 +360,13 @@
   }
 
   private <T> Object cacheAt(int offset, Supplier<T> function) {
-    if (offset == 0) return null;  // return null for offset zero.
+    if (offset == 0) {
+      return null;  // return null for offset zero.
+    }
     Object result = offsetMap.get(offset);
-    if (result != null) return result;  // return the cached result.
+    if (result != null) {
+      return result;  // return the cached result.
+    }
     // Cache is empty so parse the structure.
     file.position(offset);
     result = function.get();
@@ -812,7 +818,7 @@
   private static void populateMethodHandles(DexFileReader reader) {
     Segment segment = reader.lookupSegment(Constants.TYPE_METHOD_HANDLE_ITEM);
     reader.indexedItems.initializeMethodHandles(segment.size);
-    for (int i = 0; i < segment.size; i++){
+    for (int i = 0; i < segment.size; i++) {
       reader.indexedItems.setMethodHandle(i, reader.methodHandleAt(i));
     }
   }
@@ -820,7 +826,7 @@
   private static void populateCallSites(DexFileReader reader) {
     Segment segment = reader.lookupSegment(Constants.TYPE_CALL_SITE_ID_ITEM);
     reader.indexedItems.initializeCallSites(segment.size);
-    for (int i = 0; i < segment.size; i++){
+    for (int i = 0; i < segment.size; i++) {
       reader.indexedItems.setCallSites(i, reader.callSiteAt(i));
     }
   }
@@ -828,7 +834,7 @@
   private static void populateTypes(DexFileReader reader) {
     Segment segment = reader.lookupSegment(Constants.TYPE_TYPE_ID_ITEM);
     reader.indexedItems.initializeTypes(segment.size);
-    for (int i = 0; i < segment.size; i++){
+    for (int i = 0; i < segment.size; i++) {
       reader.indexedItems.setType(i, reader.typeAt(i));
     }
   }
@@ -836,7 +842,7 @@
   private static void populateFields(DexFileReader reader) {
     Segment segment = reader.lookupSegment(Constants.TYPE_FIELD_ID_ITEM);
     reader.indexedItems.initializeFields(segment.size);
-    for (int i = 0; i < segment.size; i++){
+    for (int i = 0; i < segment.size; i++) {
       reader.indexedItems.setField(i, reader.fieldAt(i));
     }
   }
@@ -844,7 +850,7 @@
   private static void populateProtos(DexFileReader reader) {
     Segment segment = reader.lookupSegment(Constants.TYPE_PROTO_ID_ITEM);
     reader.indexedItems.initializeProtos(segment.size);
-    for (int i = 0; i < segment.size; i++){
+    for (int i = 0; i < segment.size; i++) {
       reader.indexedItems.setProto(i, reader.protoAt(i));
     }
   }
@@ -852,7 +858,7 @@
   private static void populateMethods(DexFileReader reader) {
     Segment segment = reader.lookupSegment(Constants.TYPE_METHOD_ID_ITEM);
     reader.indexedItems.initializeMethods(segment.size);
-    for (int i = 0; i < segment.size; i++){
+    for (int i = 0; i < segment.size; i++) {
       reader.indexedItems.setMethod(i, reader.methodAt(i));
     }
   }
diff --git a/src/main/java/com/android/tools/r8/optimize/DebugStripper.java b/src/main/java/com/android/tools/r8/optimize/DebugStripper.java
index d045f76..998bc8d 100644
--- a/src/main/java/com/android/tools/r8/optimize/DebugStripper.java
+++ b/src/main/java/com/android/tools/r8/optimize/DebugStripper.java
@@ -17,9 +17,10 @@
 import com.android.tools.r8.naming.MemberNaming;
 import com.android.tools.r8.naming.MemberNaming.Range;
 import com.android.tools.r8.naming.MemberNaming.Signature;
-import com.android.tools.r8.utils.HashMapInt;
 import com.android.tools.r8.utils.InternalOptions;
 import com.google.common.collect.ImmutableMap;
+import it.unimi.dsi.fastutil.objects.Reference2IntMap;
+import it.unimi.dsi.fastutil.objects.Reference2IntOpenHashMap;
 import java.util.List;
 
 public class DebugStripper {
@@ -50,6 +51,7 @@
   }
 
   private static class NumberedDebugInfo {
+
     final int numberOfEntries;
     final DexDebugInfo info;
 
@@ -103,7 +105,7 @@
   }
 
   private void processCode(DexEncodedMethod encodedMethod, MemberNaming naming,
-      HashMapInt<DexString> nameCounts) {
+      Reference2IntMap<DexString> nameCounts) {
     if (encodedMethod.getCode() == null) {
       return;
     }
@@ -118,7 +120,7 @@
     if (options.skipDebugLineNumberOpt) {
       startLine = originalInfo.startLine;
     } else {
-      int nameCount = nameCounts.get(name);
+      int nameCount = nameCounts.getInt(name);
       if (nameCount == USED_ONCE) {
         isUsedOnce = true;
         startLine = 0;
@@ -132,7 +134,7 @@
     DexDebugInfo newInfo = numberedInfo.info;
     if (!options.skipDebugLineNumberOpt) {
       // Fix up the line information.
-      int previousCount = nameCounts.get(name);
+      int previousCount = nameCounts.getInt(name);
       nameCounts.put(name, previousCount + numberedInfo.numberOfEntries);
       // If we don't actually need line information and there are no debug entries, throw it away.
       if (newInfo != null && isUsedOnce && newInfo.events.length == 0) {
@@ -147,7 +149,7 @@
   }
 
   private void processMethod(DexEncodedMethod method, ClassNaming classNaming,
-      HashMapInt<DexString> nameCounts) {
+      Reference2IntMap<DexString> nameCounts) {
     MemberNaming naming = null;
     if (classNaming != null) {
       Signature renamedSignature = classNameMapper.getRenamedMethodSignature(method.method);
@@ -157,7 +159,7 @@
   }
 
   private void processMethods(DexEncodedMethod[] methods, ClassNaming naming,
-      HashMapInt<DexString> nameCounts) {
+      Reference2IntMap<DexString> nameCounts) {
     if (methods == null) {
       return;
     }
@@ -172,14 +174,14 @@
     }
     String name = descriptorToName(clazz.type.toDescriptorString());
     ClassNaming naming = classNameMapper == null ? null : classNameMapper.getClassNaming(name);
-    HashMapInt<DexString> nameCounts = new HashMapInt<>();
+    Reference2IntMap<DexString> nameCounts = new Reference2IntOpenHashMap<>();
     setIntialNameCounts(nameCounts, clazz.directMethods());
     setIntialNameCounts(nameCounts, clazz.virtualMethods());
     processMethods(clazz.directMethods(), naming, nameCounts);
     processMethods(clazz.virtualMethods(), naming, nameCounts);
   }
 
-  private void setIntialNameCounts(HashMapInt<DexString> nameCounts,
+  private void setIntialNameCounts(Reference2IntMap<DexString> nameCounts,
       DexEncodedMethod[] methods) {
     for (DexEncodedMethod method : methods) {
       if (nameCounts.containsKey(method.method.name)) {
diff --git a/src/main/java/com/android/tools/r8/shaking/SimpleClassMerger.java b/src/main/java/com/android/tools/r8/shaking/SimpleClassMerger.java
index bc43ae8..a2864e4 100644
--- a/src/main/java/com/android/tools/r8/shaking/SimpleClassMerger.java
+++ b/src/main/java/com/android/tools/r8/shaking/SimpleClassMerger.java
@@ -23,9 +23,6 @@
 import com.android.tools.r8.optimize.InvokeSingleTargetExtractor;
 import com.android.tools.r8.shaking.Enqueuer.AppInfoWithLiveness;
 import com.android.tools.r8.utils.FieldSignatureEquivalence;
-import com.android.tools.r8.utils.HashMapInt;
-import com.android.tools.r8.utils.IdentityHashMapInt;
-import com.android.tools.r8.utils.IntIntHashMap;
 import com.android.tools.r8.utils.MethodSignatureEquivalence;
 import com.android.tools.r8.utils.Timing;
 import com.google.common.base.Equivalence;
@@ -33,6 +30,10 @@
 import com.google.common.collect.Iterables;
 import com.google.common.collect.Iterators;
 import com.google.common.collect.Sets;
+import it.unimi.dsi.fastutil.ints.Int2IntMap;
+import it.unimi.dsi.fastutil.ints.Int2IntOpenHashMap;
+import it.unimi.dsi.fastutil.objects.Reference2IntMap;
+import it.unimi.dsi.fastutil.objects.Reference2IntOpenHashMap;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.HashMap;
@@ -274,7 +275,7 @@
     }
 
     private <T> Set<T> mergeArrays(T[] one, T[] other) {
-      Set<T> merged = new LinkedHashSet<T>();
+      Set<T> merged = new LinkedHashSet<>();
       Collections.addAll(merged, one);
       Collections.addAll(merged, other);
       return merged;
@@ -513,22 +514,26 @@
 
   private static class CollisionDetector {
 
+    private static int NOT_FOUND = 1 << (Integer.SIZE - 1);
+
     // TODO(herhut): Maybe cache seenPositions for target classes.
-    private final Map<DexString, IntIntHashMap> seenPositions = new IdentityHashMap<>();
-    private final HashMapInt<DexProto> targetProtoCache;
-    private final HashMapInt<DexProto> sourceProtoCache;
+    private final Map<DexString, Int2IntMap> seenPositions = new IdentityHashMap<>();
+    private final Reference2IntMap<DexProto> targetProtoCache;
+    private final Reference2IntMap<DexProto> sourceProtoCache;
     private final DexType source, target;
-    private final Set<DexMethod> invokes;
+    private final Collection<DexMethod> invokes;
     private final Map<DexType, DexType> substituions;
 
-    private CollisionDetector(DexType source, DexType target, Set<DexMethod> invokes,
+    private CollisionDetector(DexType source, DexType target, Collection<DexMethod> invokes,
         Map<DexType, DexType> substitutions) {
       this.source = source;
       this.target = target;
       this.invokes = invokes;
       this.substituions = substitutions;
-      this.targetProtoCache = new IdentityHashMapInt<>(invokes.size() / 2);
-      this.sourceProtoCache = new IdentityHashMapInt<>(invokes.size() / 2);
+      this.targetProtoCache = new Reference2IntOpenHashMap<>(invokes.size() / 2);
+      this.targetProtoCache.defaultReturnValue(NOT_FOUND);
+      this.sourceProtoCache = new Reference2IntOpenHashMap<>(invokes.size() / 2);
+      this.sourceProtoCache.defaultReturnValue(NOT_FOUND);
     }
 
     boolean mayCollide() {
@@ -538,11 +543,11 @@
         return false;
       }
       for (DexMethod method : invokes) {
-        IntIntHashMap positionsMap = seenPositions.get(method.name);
+        Int2IntMap positionsMap = seenPositions.get(method.name);
         if (positionsMap != null) {
           int arity = method.proto.parameters.values.length;
-          if (positionsMap.containsKey(arity)) {
-            int previous = positionsMap.get(arity);
+          int previous = positionsMap.get(arity);
+          if (previous != NOT_FOUND) {
             assert previous != 0;
             int positions = computePositionsFor(method.proto, source, sourceProtoCache,
                 substituions);
@@ -561,55 +566,58 @@
         int arity = parameters.length;
         int positions = computePositionsFor(method.proto, target, targetProtoCache, substituions);
         if (positions != 0) {
-          IntIntHashMap positionsMap =
-              seenPositions.computeIfAbsent(method.name, k -> new IntIntHashMap());
+          Int2IntMap positionsMap =
+              seenPositions.computeIfAbsent(method.name, k -> {
+                Int2IntMap result = new Int2IntOpenHashMap();
+                result.defaultReturnValue(NOT_FOUND);
+                return result;
+              });
           int value = 0;
-          if (positionsMap.containsKey(arity)) {
-            value = positionsMap.get(arity);
+          int previous = positionsMap.get(arity);
+          if (previous != NOT_FOUND) {
+            value = previous;
           }
           value |= positions;
           positionsMap.put(arity, value);
         }
       }
-      int filled = 0;
-      for (IntIntHashMap pos : seenPositions.values()) {
-        filled += pos.size();
-      }
+
     }
 
     private int computePositionsFor(DexProto proto, DexType type,
-        HashMapInt<DexProto> cache, Map<DexType, DexType> substituions) {
-      if (cache.containsKey(proto)) {
-        return cache.get(proto);
+        Reference2IntMap<DexProto> cache, Map<DexType, DexType> substitutions) {
+      int result = cache.getInt(proto);
+      if (result != NOT_FOUND) {
+        return result;
       }
-      int result = 0;
-      int bits = 0;
+      result = 0;
+      int bitsUsed = 0;
       int accumulator = 0;
       for (DexType aType : proto.parameters.values) {
-        if (substituions != null) {
+        if (substitutions != null) {
           // Substitute the type with the already merged class to estimate what it will
           // look like.
-          while (substituions.containsKey(aType)) {
-            aType = substituions.get(aType);
+          while (substitutions.containsKey(aType)) {
+            aType = substitutions.get(aType);
           }
         }
         accumulator <<= 1;
-        bits++;
+        bitsUsed++;
         if (aType == type) {
           accumulator |= 1;
         }
-        // Handle overflow on 32 bit boundary.
-        if (bits == Integer.SIZE) {
+        // Handle overflow on 31 bit boundary.
+        if (bitsUsed == Integer.SIZE - 1) {
           result |= accumulator;
           accumulator = 0;
-          bits = 0;
+          bitsUsed = 0;
         }
       }
       // We also take the return type into account for potential conflicts.
       DexType returnType = proto.returnType;
-      if (substituions != null) {
-        while (substituions.containsKey(returnType)) {
-          returnType = substituions.get(returnType);
+      if (substitutions != null) {
+        while (substitutions.containsKey(returnType)) {
+          returnType = substitutions.get(returnType);
         }
       }
       accumulator <<= 1;
diff --git a/src/main/java/com/android/tools/r8/utils/HashMapInt.java b/src/main/java/com/android/tools/r8/utils/HashMapInt.java
deleted file mode 100644
index 7e91644..0000000
--- a/src/main/java/com/android/tools/r8/utils/HashMapInt.java
+++ /dev/null
@@ -1,120 +0,0 @@
-// Copyright (c) 2016, the R8 project authors. Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-package com.android.tools.r8.utils;
-
-// Hash map based on open addressing where keys are Objects and values are basic ints.
-// Provides: put, get, and size.
-
-import java.util.Arrays;
-import java.util.Iterator;
-import java.util.Objects;
-
-public class HashMapInt<T> extends SimpleHashMap {
-
-  private Object[] keys;
-  private int[] values;
-
-  public HashMapInt() {
-    super();
-  }
-
-  public HashMapInt(int initialCapacity) {
-    super(initialCapacity);
-  }
-
-  public HashMapInt(int initialCapacity, double loadFactor) {
-    super(initialCapacity, loadFactor);
-  }
-
-  public void put(final T key, final int value) {
-    if (key == null) {
-      throw new RuntimeException("HashMapInt does not support null as key.");
-    }
-    ensureCapacity();
-    basePut(key, value);
-  }
-
-  boolean equals(Object one, Object other) {
-    return one.equals(other);
-  }
-
-  public int get(final T key) {
-    if (key == null) {
-      throw new RuntimeException("HashMapInt does not support null as key.");
-    }
-    int count = 1;
-    int index = firstProbe(key);
-    while (!equals(key, keys[index])) {
-      if (keys[index] == null) {
-        throw new RuntimeException("HashMapInt get only works if key is present.");
-      }
-      index = nextProbe(index, count++);
-    }
-    return values[index];
-  }
-
-  int firstProbe(T key) {
-    return firstProbe(key.hashCode());
-  }
-
-  public boolean containsKey(final T key) {
-    if (key == null) {
-      throw new RuntimeException("HashMapInt does not support null as key.");
-    }
-    int count = 1;
-    for (int index = firstProbe(key); ; index = nextProbe(index, count++)) {
-      Object k = keys[index];
-      if (k == null) {
-        return false;
-      }
-      if (equals(k, key)) {
-        return true;
-      }
-    }
-  }
-
-  private void basePut(final T key, final int value) {
-    int count = 1;
-    int index = firstProbe(key);
-    while ((keys[index] != null) && (keys[index] != key)) {
-      index = nextProbe(index, count++);
-    }
-    if (keys[index] == null) {
-      keys[index] = key;
-      incrementSize();
-    }
-    values[index] = value;
-  }
-
-  @SuppressWarnings("unchecked")
-  public Iterable<Integer> values() {
-    return () -> Arrays.stream(keys).filter(Objects::nonNull).map((key) -> get((T) key)).iterator();
-  }
-
-  @SuppressWarnings("unchecked")
-  public Iterable<T> keys() {
-    return () -> (Iterator<T>) Arrays.stream(keys).filter(Objects::nonNull).iterator();
-  }
-
-  @SuppressWarnings("unchecked")
-  void resize() {
-    final Object[] oldKeys = keys;
-    final int[] oldValues = values;
-    final int oldLength = length();
-    super.resize();
-    // Repopulate.
-    for (int index = 0; index < oldLength; index++) {
-      T key = (T) oldKeys[index];
-      if (key != null) {
-        basePut(key, oldValues[index]);
-      }
-    }
-  }
-
-  void initialize(final int length, final int limit) {
-    super.initialize(length, limit);
-    keys = new Object[length];
-    values = new int[length];
-  }
-}
diff --git a/src/main/java/com/android/tools/r8/utils/IdentityHashMapInt.java b/src/main/java/com/android/tools/r8/utils/IdentityHashMapInt.java
deleted file mode 100644
index 66e62ac..0000000
--- a/src/main/java/com/android/tools/r8/utils/IdentityHashMapInt.java
+++ /dev/null
@@ -1,29 +0,0 @@
-// Copyright (c) 2017, the R8 project authors. Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-package com.android.tools.r8.utils;
-
-public class IdentityHashMapInt<T> extends HashMapInt<T> {
-
-  public IdentityHashMapInt() {
-    super();
-  }
-
-  public IdentityHashMapInt(int initialCapacity) {
-    super(initialCapacity);
-  }
-
-  public IdentityHashMapInt(int initialCapacity, double loadFactor) {
-    super(initialCapacity, loadFactor);
-  }
-
-  @Override
-  int firstProbe(T key) {
-    return firstProbe(System.identityHashCode(key));
-  }
-
-  @Override
-  boolean equals(Object one, Object other) {
-    return one == other;
-  }
-}
diff --git a/src/main/java/com/android/tools/r8/utils/IntHashMap.java b/src/main/java/com/android/tools/r8/utils/IntHashMap.java
deleted file mode 100644
index 6a92316..0000000
--- a/src/main/java/com/android/tools/r8/utils/IntHashMap.java
+++ /dev/null
@@ -1,113 +0,0 @@
-// Copyright (c) 2016, the R8 project authors. Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-package com.android.tools.r8.utils;
-
-// Hash map based on open addressing where keys are basic ints and values are Objects.
-// Provides: put, get, and size.
-
-import java.util.Arrays;
-import java.util.Iterator;
-import java.util.Objects;
-import java.util.stream.IntStream;
-
-public class IntHashMap<T> extends SimpleHashMap {
-
-  private int[] keys;
-  private Object[] values;
-
-  public IntHashMap() {
-    super();
-  }
-
-  public IntHashMap(int initialCapacity) {
-    super(initialCapacity);
-  }
-
-  public IntHashMap(int initialCapacity, double loadFactor) {
-    super(initialCapacity, loadFactor);
-  }
-
-  public void put(final int key, final T value) {
-    if (value == null) {
-      throw new RuntimeException("IntHashMap does not support null as value.");
-    }
-    ensureCapacity();
-    basePut(key, value);
-  }
-
-  public T get(final int key) {
-    int count = 1;
-    int index = firstProbe(computeHash(key));
-    // Note that unused entries in keys is 0.
-    // That means we only need to check for value != null when key == 0.
-    while ((keys[index] != key) && (values[index] != null)) {
-      index = nextProbe(index, count++);
-    }
-    assert (keys[index] == key) || (values[index] == null);
-    @SuppressWarnings("unchecked")
-    T result = (T) values[index];
-    return result;
-  }
-
-  private void basePut(final int key, final Object value) {
-    assert value != null;
-    int count = 1;
-    int index = firstProbe(computeHash(key));
-    while ((values[index] != null) && (keys[index] != key)) {
-      index = nextProbe(index, count++);
-    }
-    if (values[index] == null) {
-      keys[index] = key;
-      incrementSize();
-    }
-    values[index] = value;
-    assert value.equals(get(key));
-  }
-
-  void resize() {
-    final int[] oldKeys = keys;
-    final Object[] oldValues = values;
-    final int oldLength = length();
-    super.resize();
-    // Repopulate.
-    for (int index = 0; index < oldLength; index++) {
-      Object value = oldValues[index];
-      if (value != null) {
-        basePut(oldKeys[index], value);
-      }
-    }
-  }
-
-  void initialize(final int length, final int limit) {
-    super.initialize(length, limit);
-    keys = new int[length];
-    values = new Object[length];
-  }
-
-  @SuppressWarnings("unchecked")
-  public Iterable<T> values() {
-    return () -> (Iterator<T>) Arrays.stream(values).filter(Objects::nonNull).iterator();
-  }
-
-  public Iterable<Integer> keys() {
-    if (get(0) != null) {
-      return () -> IntStream.concat(IntStream.of(0), Arrays.stream(keys).filter(i -> i != 0))
-          .iterator();
-    }
-    return () -> Arrays.stream(keys).filter(i -> i != 0 || get(i) != null).distinct().iterator();
-  }
-
-  // Thomas Wang, Integer Hash Functions.
-  // http://www.concentric.net/~Ttwang/tech/inthash.htm
-  private static int computeHash(final int key) {
-    int hash = key;
-    hash = ~hash + (hash << 15);  // hash = (hash << 15) - hash - 1;
-    hash = hash ^ (hash >> 12);
-    hash = hash + (hash << 2);
-    hash = hash ^ (hash >> 4);
-    hash = hash * 2057;  // hash = (hash + (hash << 3)) + (hash << 11);
-    hash = hash ^ (hash >> 16);
-    return hash & 0x3fffffff;
-  }
-}
diff --git a/src/main/java/com/android/tools/r8/utils/IntIntHashMap.java b/src/main/java/com/android/tools/r8/utils/IntIntHashMap.java
deleted file mode 100644
index 03d4911..0000000
--- a/src/main/java/com/android/tools/r8/utils/IntIntHashMap.java
+++ /dev/null
@@ -1,113 +0,0 @@
-// Copyright (c) 2017, the R8 project authors. Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-package com.android.tools.r8.utils;
-
-// Hash map based on open addressing where keys are positive basic ints and values are basic ints.
-// Provides: put, get, and size.
-
-import java.util.Arrays;
-
-public class IntIntHashMap extends SimpleHashMap {
-
-  private final int EMPTY_KEY = -1;
-
-  private int[] keys;
-  private int[] values;
-
-  public IntIntHashMap() {
-    super();
-  }
-
-  public IntIntHashMap(int initialCapacity) {
-    super(initialCapacity);
-  }
-
-  public IntIntHashMap(int initialCapacity, double loadFactor) {
-    super(initialCapacity, loadFactor);
-  }
-
-  public void put(final int key, final int value) {
-    if (key < 0) {
-      throw new RuntimeException("IntIntHashMap does not support negative ints as key.");
-    }
-    ensureCapacity();
-    basePut(key, value);
-  }
-
-  public int get(final int key) {
-    if (key < 0) {
-      throw new RuntimeException("IntIntHashMap does not support negative ints as key.");
-    }
-    int count = 1;
-    int index = firstProbe(key);
-    while (key != keys[index]) {
-      if (keys[index] == EMPTY_KEY) {
-        throw new RuntimeException("IntIntHashMap get only works if key is present.");
-      }
-      index = nextProbe(index, count++);
-    }
-    return values[index];
-  }
-
-  public boolean containsKey(final int key) {
-    if (key < 0) {
-      throw new RuntimeException("IntIntHashMap does not support negative ints as key.");
-    }
-    int count = 1;
-    for (int index = firstProbe(key); ; index = nextProbe(index, count++)) {
-      int k = keys[index];
-      if (k == EMPTY_KEY) {
-        return false;
-      }
-      if (k == key) {
-        return true;
-      }
-    }
-  }
-
-  private void basePut(final int key, final int value) {
-    int count = 1;
-    int index = firstProbe(key);
-    while ((keys[index] != EMPTY_KEY) && (keys[index] != key)) {
-      index = nextProbe(index, count++);
-    }
-    if (keys[index] != key) {
-      incrementSize();
-      keys[index] = key;
-    }
-    values[index] = value;
-  }
-
-  void resize() {
-    final int[] oldKeys = keys;
-    final int[] oldValues = values;
-    final int oldLength = length();
-    super.resize();
-    // Repopulate.
-    for (int index = 0; index < oldLength; index++) {
-      int key = oldKeys[index];
-      if (key != EMPTY_KEY) {
-        basePut(key, oldValues[index]);
-      }
-    }
-  }
-
-  void initialize(final int length, final int limit) {
-    super.initialize(length, limit);
-    keys = new int[length];
-    Arrays.fill(keys, EMPTY_KEY);
-    values = new int[length];
-  }
-
-
-  @SuppressWarnings("unchecked")
-  public Iterable<Integer> values() {
-    return () -> Arrays.stream(keys).filter(k -> k > EMPTY_KEY).map(this::get).iterator();
-  }
-
-  @SuppressWarnings("unchecked")
-  public Iterable<Integer> keys() {
-    return () -> Arrays.stream(keys).filter(k -> k > EMPTY_KEY).iterator();
-  }
-}
diff --git a/src/test/java/com/android/tools/r8/utils/HashMapIntTest.java b/src/test/java/com/android/tools/r8/utils/HashMapIntTest.java
deleted file mode 100644
index 5d8fffe..0000000
--- a/src/test/java/com/android/tools/r8/utils/HashMapIntTest.java
+++ /dev/null
@@ -1,81 +0,0 @@
-// Copyright (c) 2016, the R8 project authors. Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-package com.android.tools.r8.utils;
-
-import com.google.common.collect.ImmutableSet;
-import com.google.common.collect.Iterables;
-import java.util.Random;
-import java.util.Set;
-import org.junit.Assert;
-import org.junit.Test;
-
-public class HashMapIntTest {
-
-  static private String getString(int i) {
-    String SALTCHARS = "ABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890";
-    StringBuilder salt = new StringBuilder();
-    Random rnd = new Random();
-    while (salt.length() < 18) {
-      int index = (int) (rnd.nextFloat() * SALTCHARS.length());
-      salt.append(SALTCHARS.charAt(index));
-    }
-    salt.append(" ");
-    salt.append(i);
-    return salt.toString();
-  }
-
-  @Test(expected = RuntimeException.class)
-  public void putInvalid() throws Exception {
-    HashMapInt<Object> map = new HashMapInt<>();
-    map.put(null, 12);
-  }
-
-  @Test
-  public void put() throws Exception {
-    HashMapInt<Object> map = new HashMapInt<>();
-    Object key = new Object();
-    int value = 0;
-    map.put(key, value);
-    Assert.assertTrue(map.containsKey(key));
-    Assert.assertFalse(map.containsKey(new Object[0]));
-    Assert.assertEquals(map.get(key), value);
-    Assert.assertEquals(map.size(), 1);
-  }
-
-  @Test
-  public void random() throws Exception {
-    final int length = 5999;
-    HashMapInt<String> map = new HashMapInt<>();
-    String[] array = new String[length];
-    for (int i = 0; i < length; i++) {
-      array[i] = getString(i);
-      map.put(array[i], i * 3);
-    }
-    Assert.assertEquals(length, map.size());
-    for (int i = 0; i < length; i++) {
-      Assert.assertEquals(map.get(array[i]), i * 3);
-    }
-    for (int i : map.values()) {
-      Assert.assertTrue(i < length * 3 && i >= 0 && i % 3 == 0);
-    }
-    Assert.assertEquals(length, Iterables.size(map.values()));
-    Set<String> items = ImmutableSet.copyOf(array);
-    for (String s : map.keys()) {
-      Assert.assertTrue(items.contains(s));
-    }
-    Assert.assertEquals(length, Iterables.size(map.keys()));
-  }
-
-  @Test
-  public void overwrite() throws Exception {
-    HashMapInt<Object> map = new HashMapInt<>();
-    Object key = new Object();
-    int value1 = 0;
-    map.put(key, value1);
-    Assert.assertEquals(map.get(key), value1);
-    int value2 = -1;
-    map.put(key, value2);
-    Assert.assertEquals(map.get(key), value2);
-  }
-}
diff --git a/src/test/java/com/android/tools/r8/utils/IdentityHashMapIntTest.java b/src/test/java/com/android/tools/r8/utils/IdentityHashMapIntTest.java
deleted file mode 100644
index dd57960..0000000
--- a/src/test/java/com/android/tools/r8/utils/IdentityHashMapIntTest.java
+++ /dev/null
@@ -1,78 +0,0 @@
-// Copyright (c) 2017, the R8 project authors. Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-package com.android.tools.r8.utils;
-
-import com.google.common.collect.Iterables;
-import com.google.common.collect.Sets;
-import java.util.Collections;
-import java.util.Set;
-import org.junit.Assert;
-import org.junit.Test;
-
-public class IdentityHashMapIntTest {
-
-  @Test(expected = RuntimeException.class)
-  public void putInvalid() throws Exception {
-    IdentityHashMapInt<Object> map = new IdentityHashMapInt<>();
-    map.put(null, 12);
-  }
-
-  @Test
-  public void put() throws Exception {
-    IdentityHashMapInt<Object> map = new IdentityHashMapInt<>();
-    Object key = new AllEqual();
-    int value = 0;
-    map.put(key, value);
-    Assert.assertTrue(map.containsKey(key));
-    Assert.assertFalse(map.containsKey(new Object()));
-    Assert.assertFalse(map.containsKey(new AllEqual()));
-    Assert.assertEquals(map.get(key), value);
-    Assert.assertEquals(map.size(), 1);
-  }
-
-  @Test
-  public void random() throws Exception {
-    final int length = 5999;
-    IdentityHashMapInt<Object> map = new IdentityHashMapInt<>();
-    AllEqual[] array = new AllEqual[length];
-    for (int i = 0; i < length; i++) {
-      array[i] = new AllEqual();
-      map.put(array[i], i * 3);
-    }
-    Assert.assertEquals(length, map.size());
-    for (int i = 0; i < length; i++) {
-      Assert.assertEquals(map.get(array[i]), i * 3);
-    }
-    for (int i : map.values()) {
-      Assert.assertTrue(i < length * 3 && i >= 0 && i % 3 == 0);
-    }
-    Assert.assertEquals(length, Iterables.size(map.values()));
-    Set<Object> items = Sets.newIdentityHashSet();
-    Collections.addAll(items, array);
-    for (Object o : map.keys()) {
-      Assert.assertTrue(items.contains(o));
-    }
-    Assert.assertEquals(length, Iterables.size(map.keys()));
-  }
-
-  @Test
-  public void overwrite() throws Exception {
-    IdentityHashMapInt<Object> map = new IdentityHashMapInt<>();
-    Object key = new Object();
-    int value1 = 0;
-    map.put(key, value1);
-    Assert.assertEquals(map.get(key), value1);
-    int value2 = -1;
-    map.put(key, value2);
-    Assert.assertEquals(map.get(key), value2);
-  }
-
-  private static class AllEqual {
-
-    @Override
-    public boolean equals(Object o) {
-      return true;
-    }
-  }
-}
diff --git a/src/test/java/com/android/tools/r8/utils/IntHashMapTest.java b/src/test/java/com/android/tools/r8/utils/IntHashMapTest.java
deleted file mode 100644
index c4b4dc2..0000000
--- a/src/test/java/com/android/tools/r8/utils/IntHashMapTest.java
+++ /dev/null
@@ -1,83 +0,0 @@
-// Copyright (c) 2016, the R8 project authors. Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-package com.android.tools.r8.utils;
-
-import com.google.common.collect.ImmutableSet;
-import com.google.common.collect.Iterables;
-import java.util.Random;
-import java.util.Set;
-import org.junit.Assert;
-import org.junit.Test;
-
-public class IntHashMapTest {
-
-  static private String getRandomString() {
-    String SALTCHARS = "ABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890";
-    StringBuilder salt = new StringBuilder();
-    Random rnd = new Random();
-    while (salt.length() < 18) {
-      int index = (int) (rnd.nextFloat() * SALTCHARS.length());
-      salt.append(SALTCHARS.charAt(index));
-    }
-    return salt.toString();
-  }
-
-  @Test(expected = RuntimeException.class)
-  public void putInvalid() throws Exception {
-    IntHashMap<Object> map = new IntHashMap<>();
-    map.put(12, null);
-  }
-
-  @Test
-  public void put() throws Exception {
-    IntHashMap<Object> map = new IntHashMap<>();
-    int key = 1;
-    Object value = new Object();
-    map.put(key, value);
-    Assert.assertEquals(map.get(key), value);
-    Assert.assertEquals(map.size(), 1);
-    map.put(key + 1, value);
-    Assert.assertEquals(map.get(key + 1), value);
-    Assert.assertEquals(map.size(), 2);
-    Assert.assertEquals(map.get(0), null);
-    map.put(0, value);
-    Assert.assertEquals(map.get(0), value);
-  }
-
-  @Test
-  public void random() throws Exception {
-    final int length = 5999;
-    IntHashMap<String> map = new IntHashMap<>();
-    String[] array = new String[length];
-    for (int i = 0; i < length; i++) {
-      array[i] = getRandomString();
-      map.put(i, array[i]);
-    }
-    Assert.assertEquals(length, map.size());
-    for (int i = 0; i < length; i++) {
-      Assert.assertEquals(map.get(i), array[i]);
-    }
-    Set<String> items = ImmutableSet.copyOf(array);
-    for (String s : map.values()) {
-      Assert.assertTrue(items.contains(s));
-    }
-    Assert.assertEquals(length, Iterables.size(map.values()));
-    for (int i : map.keys()) {
-      Assert.assertTrue(i < length && i >= 0);
-    }
-    Assert.assertEquals(length, Iterables.size(map.keys()));
-  }
-
-  @Test
-  public void overwrite() throws Exception {
-    IntHashMap<Object> map = new IntHashMap<>();
-    int key = 1;
-    Object value1 = new Object();
-    map.put(key, value1);
-    Assert.assertEquals(map.get(key), value1);
-    Object value2 = new Object[0];
-    map.put(key, value2);
-    Assert.assertEquals(map.get(key), value2);
-  }
-}
diff --git a/src/test/java/com/android/tools/r8/utils/IntIntHashMapTest.java b/src/test/java/com/android/tools/r8/utils/IntIntHashMapTest.java
deleted file mode 100644
index d129a03..0000000
--- a/src/test/java/com/android/tools/r8/utils/IntIntHashMapTest.java
+++ /dev/null
@@ -1,75 +0,0 @@
-// Copyright (c) 2017, the R8 project authors. Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-package com.android.tools.r8.utils;
-
-import com.google.common.collect.Iterables;
-import java.util.Iterator;
-import java.util.LinkedHashSet;
-import java.util.Random;
-import java.util.Set;
-import org.junit.Assert;
-import org.junit.Test;
-
-public class IntIntHashMapTest {
-
-  @Test(expected = RuntimeException.class)
-  public void putInvalid() throws Exception {
-    IntIntHashMap map = new IntIntHashMap();
-    map.put(-1, 12);
-  }
-
-  @Test
-  public void put() throws Exception {
-    IntIntHashMap map = new IntIntHashMap();
-    int key = 22;
-    int value = 0;
-    map.put(key, value);
-    Assert.assertTrue(map.containsKey(key));
-    Assert.assertFalse(map.containsKey(33));
-    Assert.assertEquals(map.get(key), value);
-    Assert.assertEquals(map.size(), 1);
-  }
-
-  @Test
-  public void random() throws Exception {
-    final int length = 5999;
-    IntIntHashMap map = new IntIntHashMap();
-    Random rnd = new Random();
-    Set<Integer> seen = new LinkedHashSet<>();
-    String[] array = new String[length];
-    for (int i = 0; i < length; i++) {
-      int next;
-      do {
-        next = rnd.nextInt(4 * length);
-      } while (seen.contains(next));
-      seen.add(next);
-      map.put(next, i * 3);
-    }
-    Assert.assertEquals(seen.size(), map.size());
-    Iterator<Integer> it = seen.iterator();
-    for (int i = 0; i < length; i++) {
-      Assert.assertEquals(map.get(it.next()), i * 3);
-    }
-    for (int i : map.values()) {
-      Assert.assertTrue(i < length * 3 && i >= 0 && i % 3 == 0);
-    }
-    Assert.assertEquals(length, Iterables.size(map.values()));
-    for (Integer key : map.keys()) {
-      Assert.assertTrue(seen.contains(key));
-    }
-    Assert.assertEquals(seen.size(), Iterables.size(map.keys()));
-  }
-
-  @Test
-  public void overwrite() throws Exception {
-    IntIntHashMap map = new IntIntHashMap();
-    int key = 42;
-    int value1 = 0;
-    map.put(key, value1);
-    Assert.assertEquals(map.get(key), value1);
-    int value2 = -1;
-    map.put(key, value2);
-    Assert.assertEquals(map.get(key), value2);
-  }
-}