diff --git a/src/main/java/com/android/tools/r8/desugar/desugaredlibrary/DesugaredLibraryKeepRuleGenerator.java b/src/main/java/com/android/tools/r8/desugar/desugaredlibrary/DesugaredLibraryKeepRuleGenerator.java
index 8bdf5a1..eaec5a0 100644
--- a/src/main/java/com/android/tools/r8/desugar/desugaredlibrary/DesugaredLibraryKeepRuleGenerator.java
+++ b/src/main/java/com/android/tools/r8/desugar/desugaredlibrary/DesugaredLibraryKeepRuleGenerator.java
@@ -13,7 +13,7 @@
 import com.android.tools.r8.graph.DexProto;
 import com.android.tools.r8.graph.DexString;
 import com.android.tools.r8.graph.DexType;
-import com.android.tools.r8.ir.desugar.desugaredlibrary.legacyspecification.LegacyDesugaredLibrarySpecification;
+import com.android.tools.r8.ir.desugar.desugaredlibrary.machinespecification.MachineDesugaredLibrarySpecification;
 import com.android.tools.r8.naming.NamingLens;
 import com.android.tools.r8.references.ArrayReference;
 import com.android.tools.r8.references.ClassReference;
@@ -32,13 +32,11 @@
 import com.android.tools.r8.utils.InternalOptions;
 import com.android.tools.r8.utils.ListUtils;
 import com.android.tools.r8.utils.NopDiagnosticsHandler;
-import com.android.tools.r8.utils.SetUtils;
 import com.android.tools.r8.utils.Timing;
 import com.android.tools.r8.utils.TypeReferenceUtils;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
-import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.function.Predicate;
 
@@ -80,18 +78,15 @@
   }
 
   private Predicate<DexType> createTargetPredicate() {
-    LegacyDesugaredLibrarySpecification desugaredLibrarySpecification =
-        options.desugaredLibrarySpecification;
-    Set<DexType> potentialTypesToKeep =
-        SetUtils.newIdentityHashSet(
-            desugaredLibrarySpecification.getCustomConversions().values(),
-            desugaredLibrarySpecification.getEmulateLibraryInterface().values());
+    MachineDesugaredLibrarySpecification desugaredLibrarySpecification =
+        options.machineDesugaredLibrarySpecification;
     byte[] synthesizedLibraryClassesPackageDescriptorPrefix =
         DexString.encodeToMutf8(
             "L" + desugaredLibrarySpecification.getSynthesizedLibraryClassesPackagePrefix());
     return type ->
         namingLens.prefixRewrittenType(type) != null
-            || potentialTypesToKeep.contains(type)
+            || desugaredLibrarySpecification.isEmulatedInterfaceRewrittenType(type)
+            || desugaredLibrarySpecification.isCustomConversionRewrittenType(type)
             || type.getDescriptor().startsWith(synthesizedLibraryClassesPackageDescriptorPrefix);
   }
 
diff --git a/src/main/java/com/android/tools/r8/dex/CodeToKeep.java b/src/main/java/com/android/tools/r8/dex/CodeToKeep.java
index 3adc951..3e33ca8 100644
--- a/src/main/java/com/android/tools/r8/dex/CodeToKeep.java
+++ b/src/main/java/com/android/tools/r8/dex/CodeToKeep.java
@@ -57,22 +57,18 @@
     }
 
     private final NamingLens namingLens;
-    private final Set<DexType> potentialTypesToKeep = Sets.newIdentityHashSet();
     private final Map<DexType, KeepStruct> toKeep = new ConcurrentHashMap<>();
     private final InternalOptions options;
 
     public DesugaredLibraryCodeToKeep(NamingLens namingLens, InternalOptions options) {
       this.namingLens = namingLens;
       this.options = options;
-      potentialTypesToKeep.addAll(
-          options.machineDesugaredLibrarySpecification.getEmulatedInterfaceRewrittenTypes());
-      potentialTypesToKeep.addAll(
-          options.desugaredLibrarySpecification.getCustomConversions().values());
     }
 
     private boolean shouldKeep(DexType type) {
       return namingLens.prefixRewrittenType(type) != null
-          || potentialTypesToKeep.contains(type)
+          || options.machineDesugaredLibrarySpecification.isCustomConversionRewrittenType(type)
+          || options.machineDesugaredLibrarySpecification.isEmulatedInterfaceRewrittenType(type)
           // TODO(b/158632510): This should prefix match on DexString.
           || type.toDescriptorString()
               .startsWith(
diff --git a/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/apiconversion/DesugaredLibraryAPICallbackSynthesizer.java b/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/apiconversion/DesugaredLibraryAPICallbackSynthesizer.java
index 9b07615..b66a96a 100644
--- a/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/apiconversion/DesugaredLibraryAPICallbackSynthesizer.java
+++ b/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/apiconversion/DesugaredLibraryAPICallbackSynthesizer.java
@@ -20,13 +20,13 @@
 import com.android.tools.r8.ir.desugar.CfPostProcessingDesugaring;
 import com.android.tools.r8.ir.desugar.CfPostProcessingDesugaringEventConsumer;
 import com.android.tools.r8.ir.desugar.desugaredlibrary.apiconversion.DesugaredLibraryWrapperSynthesizerEventConsumer.DesugaredLibraryAPICallbackSynthesizorEventConsumer;
+import com.android.tools.r8.ir.desugar.desugaredlibrary.machinespecification.MachineDesugaredLibrarySpecification;
 import com.android.tools.r8.ir.synthetic.DesugaredLibraryAPIConversionCfCodeProvider.APICallbackWrapperCfCodeProvider;
 import com.android.tools.r8.utils.OptionalBool;
 import com.android.tools.r8.utils.WorkList;
 import com.google.common.collect.Sets;
 import java.util.ArrayList;
 import java.util.Collection;
-import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.ExecutorService;
 
@@ -181,10 +181,10 @@
     if (appView.options().machineDesugaredLibrarySpecification.supportAllCallbacksFromLibrary()) {
       return true;
     }
-    Map<DexType, DexType> emulateLibraryInterfaces =
-        appView.options().desugaredLibrarySpecification.getEmulateLibraryInterface();
-    return !(emulateLibraryInterfaces.containsKey(dexClass.type)
-        || emulateLibraryInterfaces.containsValue(dexClass.type));
+    MachineDesugaredLibrarySpecification specification =
+        appView.options().machineDesugaredLibrarySpecification;
+    return !(specification.getEmulatedInterfaces().containsKey(dexClass.type)
+        || specification.isEmulatedInterfaceRewrittenType(dexClass.type));
   }
 
   private ProgramMethod generateCallbackMethod(
diff --git a/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/apiconversion/DesugaredLibraryWrapperSynthesizer.java b/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/apiconversion/DesugaredLibraryWrapperSynthesizer.java
index 3769787..71442ac 100644
--- a/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/apiconversion/DesugaredLibraryWrapperSynthesizer.java
+++ b/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/apiconversion/DesugaredLibraryWrapperSynthesizer.java
@@ -465,9 +465,8 @@
       if (holderClass == null) {
         assert appView
             .options()
-            .desugaredLibrarySpecification
-            .getEmulateLibraryInterface()
-            .containsValue(method.getHolderType());
+            .machineDesugaredLibrarySpecification
+            .isEmulatedInterfaceRewrittenType(method.getHolderType());
         isInterface = true;
       } else {
         isInterface = holderClass.isInterface();
diff --git a/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/machinespecification/MachineDesugaredLibrarySpecification.java b/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/machinespecification/MachineDesugaredLibrarySpecification.java
index 7cf54a8..e1368e3 100644
--- a/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/machinespecification/MachineDesugaredLibrarySpecification.java
+++ b/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/machinespecification/MachineDesugaredLibrarySpecification.java
@@ -109,8 +109,12 @@
     return rewritingFlags.getEmulatedInterfaceEmulatedDispatchMethodDescriptor(method);
   }
 
-  public Set<DexType> getEmulatedInterfaceRewrittenTypes() {
-    return rewritingFlags.getEmulatedInterfaceRewrittenTypes();
+  public boolean isCustomConversionRewrittenType(DexType type) {
+    return rewritingFlags.isCustomConversionRewrittenType(type);
+  }
+
+  public boolean isEmulatedInterfaceRewrittenType(DexType type) {
+    return rewritingFlags.isEmulatedInterfaceRewrittenType(type);
   }
 
   public Map<DexType, List<DexMethod>> getWrappers() {
diff --git a/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/machinespecification/MachineRewritingFlags.java b/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/machinespecification/MachineRewritingFlags.java
index 666c766..c5c77c6 100644
--- a/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/machinespecification/MachineRewritingFlags.java
+++ b/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/machinespecification/MachineRewritingFlags.java
@@ -11,7 +11,7 @@
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
-import com.google.common.collect.Sets;
+import com.google.common.collect.Iterables;
 import java.util.IdentityHashMap;
 import java.util.List;
 import java.util.Map;
@@ -106,14 +106,6 @@
     return emulatedInterfaces;
   }
 
-  public Set<DexType> getEmulatedInterfaceRewrittenTypes() {
-    Set<DexType> rewrittenTypes = Sets.newIdentityHashSet();
-    emulatedInterfaces
-        .values()
-        .forEach(descriptor -> rewrittenTypes.add(descriptor.getRewrittenType()));
-    return rewrittenTypes;
-  }
-
   public Map<DexType, List<DexMethod>> getWrappers() {
     return wrappers;
   }
@@ -126,6 +118,10 @@
     return dontRetarget;
   }
 
+  public boolean isCustomConversionRewrittenType(DexType type) {
+    return Iterables.any(customConversions.values(), pair -> pair.getFirst() == type);
+  }
+
   public Map<DexType, Pair<DexType, DexString>> getCustomConversions() {
     return customConversions;
   }
@@ -136,6 +132,11 @@
         || !emulatedVirtualRetarget.isEmpty();
   }
 
+  public boolean isEmulatedInterfaceRewrittenType(DexType type) {
+    return Iterables.any(
+        emulatedInterfaces.values(), descriptor -> descriptor.getRewrittenType() == type);
+  }
+
   public boolean hasEmulatedInterfaces() {
     return !emulatedInterfaces.isEmpty();
   }
diff --git a/src/main/java/com/android/tools/r8/ir/desugar/itf/InterfaceDesugaringSyntheticHelper.java b/src/main/java/com/android/tools/r8/ir/desugar/itf/InterfaceDesugaringSyntheticHelper.java
index a77507a..cb4a537 100644
--- a/src/main/java/com/android/tools/r8/ir/desugar/itf/InterfaceDesugaringSyntheticHelper.java
+++ b/src/main/java/com/android/tools/r8/ir/desugar/itf/InterfaceDesugaringSyntheticHelper.java
@@ -38,6 +38,7 @@
 import com.android.tools.r8.ir.desugar.CfInstructionDesugaringEventConsumer;
 import com.android.tools.r8.ir.desugar.desugaredlibrary.machinespecification.DerivedMethod;
 import com.android.tools.r8.ir.desugar.desugaredlibrary.machinespecification.EmulatedDispatchMethodDescriptor;
+import com.android.tools.r8.ir.desugar.desugaredlibrary.machinespecification.EmulatedInterfaceDescriptor;
 import com.android.tools.r8.ir.desugar.itf.EmulatedInterfaceSynthesizerEventConsumer.ClasspathEmulatedInterfaceSynthesizerEventConsumer;
 import com.android.tools.r8.synthesis.SyntheticClassBuilder;
 import com.android.tools.r8.synthesis.SyntheticMethodBuilder;
@@ -45,9 +46,6 @@
 import com.android.tools.r8.utils.InternalOptions;
 import com.android.tools.r8.utils.structural.Ordered;
 import com.google.common.collect.ImmutableList;
-import java.util.IdentityHashMap;
-import java.util.Map;
-import java.util.Set;
 import java.util.function.Predicate;
 
 public class InterfaceDesugaringSyntheticHelper {
@@ -66,37 +64,32 @@
   static final String PRIVATE_METHOD_PREFIX = "$private$";
 
   private final AppView<?> appView;
-  private final Map<DexType, DexType> emulatedInterfaces;
   private final Predicate<DexType> shouldIgnoreFromReportsPredicate;
 
   public InterfaceDesugaringSyntheticHelper(AppView<?> appView) {
     this.appView = appView;
-    emulatedInterfaces = new IdentityHashMap<>();
-    appView
-        .options()
-        .machineDesugaredLibrarySpecification
-        .getEmulatedInterfaces()
-        .forEach(
-            (ei, descriptor) -> {
-              emulatedInterfaces.put(ei, descriptor.getRewrittenType());
-            });
     this.shouldIgnoreFromReportsPredicate = getShouldIgnoreFromReportsPredicate(appView);
   }
 
   boolean isEmulatedInterface(DexType itf) {
-    return emulatedInterfaces.containsKey(itf);
+    return appView
+        .options()
+        .machineDesugaredLibrarySpecification
+        .getEmulatedInterfaces()
+        .containsKey(itf);
   }
 
   boolean isRewrittenEmulatedInterface(DexType itf) {
-    return emulatedInterfaces.containsValue(itf);
-  }
-
-  Set<DexType> getEmulatedInterfaces() {
-    return emulatedInterfaces.keySet();
+    return appView
+        .options()
+        .machineDesugaredLibrarySpecification
+        .isEmulatedInterfaceRewrittenType(itf);
   }
 
   DexType getEmulatedInterface(DexType type) {
-    return emulatedInterfaces.get(type);
+    EmulatedInterfaceDescriptor interfaceDescriptor =
+        appView.options().machineDesugaredLibrarySpecification.getEmulatedInterfaces().get(type);
+    return interfaceDescriptor == null ? null : interfaceDescriptor.getRewrittenType();
   }
 
   boolean isInDesugaredLibrary(DexClass clazz) {
@@ -584,7 +577,7 @@
       return appView.rewritePrefix.hasRewrittenType(type, appView)
           || descriptor.endsWith(companionClassNameDescriptorSuffix)
           || isRewrittenEmulatedInterface(type)
-          || options.desugaredLibrarySpecification.getCustomConversions().containsValue(type)
+          || options.machineDesugaredLibrarySpecification.isCustomConversionRewrittenType(type)
           || appView.getDontWarnConfiguration().matches(type);
     };
   }
diff --git a/src/test/java/com/android/tools/r8/D8CommandTest.java b/src/test/java/com/android/tools/r8/D8CommandTest.java
index 3c46d21..cf095b1 100644
--- a/src/test/java/com/android/tools/r8/D8CommandTest.java
+++ b/src/test/java/com/android/tools/r8/D8CommandTest.java
@@ -639,7 +639,11 @@
             "--lib",
             ToolHelper.getAndroidJar(AndroidApiLevel.P).toString());
     assertFalse(
-        d8Command.getInternalOptions().desugaredLibrarySpecification.getRewritePrefix().isEmpty());
+        d8Command
+            .getInternalOptions()
+            .machineDesugaredLibrarySpecification
+            .getRewriteType()
+            .isEmpty());
   }
 
   @Test
diff --git a/src/test/java/com/android/tools/r8/L8CommandTest.java b/src/test/java/com/android/tools/r8/L8CommandTest.java
index 73da19e..358d863 100644
--- a/src/test/java/com/android/tools/r8/L8CommandTest.java
+++ b/src/test/java/com/android/tools/r8/L8CommandTest.java
@@ -361,7 +361,11 @@
             "--lib",
             ToolHelper.getAndroidJar(AndroidApiLevel.P).toString());
     assertFalse(
-        l8Command.getInternalOptions().desugaredLibrarySpecification.getRewritePrefix().isEmpty());
+        l8Command
+            .getInternalOptions()
+            .machineDesugaredLibrarySpecification
+            .getRewriteType()
+            .isEmpty());
   }
 
   private void checkSingleForceAllAssertion(
diff --git a/src/test/java/com/android/tools/r8/R8CommandTest.java b/src/test/java/com/android/tools/r8/R8CommandTest.java
index 2c0a77e..325344f 100644
--- a/src/test/java/com/android/tools/r8/R8CommandTest.java
+++ b/src/test/java/com/android/tools/r8/R8CommandTest.java
@@ -770,7 +770,11 @@
             "--lib",
             ToolHelper.getAndroidJar(AndroidApiLevel.P).toString());
     assertFalse(
-        r8Command.getInternalOptions().desugaredLibrarySpecification.getRewritePrefix().isEmpty());
+        r8Command
+            .getInternalOptions()
+            .machineDesugaredLibrarySpecification
+            .getRewriteType()
+            .isEmpty());
   }
 
   @Test
@@ -785,7 +789,11 @@
             "--desugared-lib-pg-conf-output",
             pgout.toString());
     assertFalse(
-        r8Command.getInternalOptions().desugaredLibrarySpecification.getRewritePrefix().isEmpty());
+        r8Command
+            .getInternalOptions()
+            .machineDesugaredLibrarySpecification
+            .getRewriteType()
+            .isEmpty());
   }
 
   @Test