Add a genrule that generates a dummy J2ObjC dead code removal script in tools/objc/BUILD.

--
MOS_MIGRATED_REVID=93447039

16 files changed, 265 insertions, 34 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/BinaryLinkingTargetFactory.java b/src/main/java/com/google/devtools/build/lib/rules/objc/BinaryLinkingTargetFactory.java
index fde2683978..e822a0f3fc 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/BinaryLinkingTargetFactory.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/BinaryLinkingTargetFactory.java
@@ -145,7 +145,8 @@ abstract class BinaryLinkingTargetFactory implements RuleConfiguredTargetFactory
         Optional.of(xcodeProvider),
         Optional.of(objcProvider),
         xcTestAppProvider,
-        Optional.<J2ObjcSrcsProvider>absent());
+        Optional.<J2ObjcSrcsProvider>absent(),
+        Optional.<J2ObjcMappingFileProvider>absent());
     for (RunfilesSupport runfilesSupport : maybeRunfilesSupport.asSet()) {
       target.setRunfilesSupport(runfilesSupport, runfilesSupport.getExecutable());
     }
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/CompilationSupport.java b/src/main/java/com/google/devtools/build/lib/rules/objc/CompilationSupport.java
index 132cf86c4c..ed6edea8ab 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/CompilationSupport.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/CompilationSupport.java
@@ -14,6 +14,7 @@
 
 package com.google.devtools.build.lib.rules.objc;
 
+import static com.google.devtools.build.lib.rules.objc.J2ObjcSource.SourceType;
 import static com.google.devtools.build.lib.rules.objc.ObjcProvider.DEFINE;
 import static com.google.devtools.build.lib.rules.objc.ObjcProvider.FORCE_LOAD_LIBRARY;
 import static com.google.devtools.build.lib.rules.objc.ObjcProvider.FRAMEWORK_DIR;
@@ -48,6 +49,7 @@ import com.google.devtools.build.lib.analysis.actions.CommandLine;
 import com.google.devtools.build.lib.analysis.actions.CustomCommandLine;
 import com.google.devtools.build.lib.analysis.actions.FileWriteAction;
 import com.google.devtools.build.lib.analysis.actions.SpawnAction;
+import com.google.devtools.build.lib.collect.nestedset.NestedSet;
 import com.google.devtools.build.lib.rules.objc.ObjcCommon.CompilationAttributes;
 import com.google.devtools.build.lib.rules.objc.XcodeProvider.Builder;
 import com.google.devtools.build.lib.shell.ShellUtils;
@@ -410,11 +412,28 @@ final class CompilationSupport {
    */
   CompilationSupport registerJ2ObjcCompileAndArchiveActions(
       OptionsProvider optionsProvider, ObjcProvider objcProvider) {
-    for (J2ObjcSource j2ObjcSource : ObjcRuleClasses.j2ObjcSrcsProvider(ruleContext).getSrcs()) {
+    J2ObjcSrcsProvider provider = ObjcRuleClasses.j2ObjcSrcsProvider(ruleContext);
+    Iterable<J2ObjcSource> j2ObjcSources = provider.getSrcs();
+    J2ObjcConfiguration j2objcConfiguration = ruleContext.getFragment(J2ObjcConfiguration.class);
+
+    // Only perform J2ObjC dead code stripping if flag --j2objc_dead_code_removal is specified and
+    // users have specified entry classes.
+    boolean stripJ2ObjcDeadCode = j2objcConfiguration.removeDeadCode()
+        && !provider.getEntryClasses().isEmpty();
+
+    if (stripJ2ObjcDeadCode) {
+      registerJ2ObjcDeadCodeRemovalActions(j2ObjcSources, provider.getEntryClasses());
+    }
+
+    for (J2ObjcSource j2ObjcSource : j2ObjcSources) {
+      J2ObjcSource sourceToCompile =
+          j2ObjcSource.getSourceType() == SourceType.JAVA && stripJ2ObjcDeadCode
+              ? j2ObjcSource.toPrunedSource(ruleContext)
+              : j2ObjcSource;
       IntermediateArtifacts intermediateArtifacts =
-          ObjcRuleClasses.j2objcIntermediateArtifacts(ruleContext, j2ObjcSource);
+          ObjcRuleClasses.j2objcIntermediateArtifacts(ruleContext, sourceToCompile);
       CompilationArtifacts compilationArtifact = new CompilationArtifacts.Builder()
-          .addNonArcSrcs(j2ObjcSource.getObjcSrcs())
+          .addNonArcSrcs(sourceToCompile.getObjcSrcs())
           .setIntermediateArtifacts(intermediateArtifacts)
           .setPchFile(Optional.<Artifact>absent())
           .build();
@@ -425,6 +444,40 @@ final class CompilationSupport {
     return this;
   }
 
+  private void registerJ2ObjcDeadCodeRemovalActions(Iterable<J2ObjcSource> j2ObjcSources,
+      Iterable<String> entryClasses) {
+    Artifact pruner = ruleContext.getPrerequisiteArtifact("$j2objc_dead_code_pruner", Mode.HOST);
+    J2ObjcMappingFileProvider provider = ObjcRuleClasses.j2ObjcMappingFileProvider(ruleContext);
+    NestedSet<Artifact> j2ObjcDependencyMappingFiles = provider.getDependencyMappingFiles();
+    NestedSet<Artifact> j2ObjcHeaderMappingFiles = provider.getHeaderMappingFiles();
+
+    for (J2ObjcSource j2ObjcSource : j2ObjcSources) {
+      if (j2ObjcSource.getSourceType() == SourceType.JAVA) {
+        Iterable<Artifact> sourceArtifacts = j2ObjcSource.getObjcSrcs();
+        Iterable<Artifact> prunedSourceArtifacts =
+            j2ObjcSource.toPrunedSource(ruleContext).getObjcSrcs();
+        PathFragment objcFilePath = j2ObjcSource.getObjcFilePath();
+        ruleContext.registerAction(new SpawnAction.Builder()
+            .setMnemonic("DummyPruner")
+            .setExecutable(pruner)
+            .addInput(pruner)
+            .addInputs(sourceArtifacts)
+            .addTransitiveInputs(j2ObjcDependencyMappingFiles)
+            .addTransitiveInputs(j2ObjcHeaderMappingFiles)
+            .setCommandLine(CustomCommandLine.builder()
+                .addJoinExecPaths("--input_files", ",", sourceArtifacts)
+                .addJoinExecPaths("--output_files", ",", prunedSourceArtifacts)
+                .addJoinExecPaths("--dependency_mapping_files", ",", j2ObjcDependencyMappingFiles)
+                .addJoinExecPaths("--header_mapping_files", ",", j2ObjcHeaderMappingFiles)
+                .add("--entry_classes").add(Joiner.on(",").join(entryClasses))
+                .add("--objc_file_path").add(objcFilePath.getPathString())
+                .build())
+            .addOutputs(prunedSourceArtifacts)
+            .build(ruleContext));
+      }
+    }
+  }
+
   /**
    * Sets compilation-related Xcode project information on the given provider builder.
    *
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/J2ObjcCommandLineOptions.java b/src/main/java/com/google/devtools/build/lib/rules/objc/J2ObjcCommandLineOptions.java
index d6d9cad47f..7d1f88b4d4 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/J2ObjcCommandLineOptions.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/J2ObjcCommandLineOptions.java
@@ -35,6 +35,14 @@ public class J2ObjcCommandLineOptions extends FragmentOptions {
       )
   public List<String> translationFlags;
 
+  @Option(name = "j2objc_dead_code_removal",
+      defaultValue = "false",
+      category = "undocumented",
+      help = "Whether to perform J2ObjC dead code removal to strip unused code from the final app "
+          + "bundle."
+      )
+  public boolean removeDeadCode;
+
   @Override
   public void addAllLabels(Multimap<String, Label> labelMap) {}
 }
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/J2ObjcConfiguration.java b/src/main/java/com/google/devtools/build/lib/rules/objc/J2ObjcConfiguration.java
index 35b24d1ce9..116030b2ab 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/J2ObjcConfiguration.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/J2ObjcConfiguration.java
@@ -20,7 +20,8 @@ import com.google.devtools.build.lib.analysis.config.BuildConfiguration.Fragment
 import com.google.devtools.build.lib.analysis.config.BuildOptions;
 import com.google.devtools.build.lib.analysis.config.ConfigurationEnvironment;
 import com.google.devtools.build.lib.analysis.config.ConfigurationFragmentFactory;
-import com.google.devtools.build.lib.analysis.config.InvalidConfigurationException;
+import com.google.devtools.build.lib.events.Event;
+import com.google.devtools.build.lib.events.EventHandler;
 
 import java.util.Collections;
 import java.util.Set;
@@ -56,8 +57,7 @@ public class J2ObjcConfiguration extends Fragment {
    */
   public static class Loader implements ConfigurationFragmentFactory {
     @Override
-    public Fragment create(ConfigurationEnvironment env, BuildOptions buildOptions)
-        throws InvalidConfigurationException {
+    public Fragment create(ConfigurationEnvironment env, BuildOptions buildOptions) {
       return new J2ObjcConfiguration(buildOptions.get(J2ObjcCommandLineOptions.class));
     }
 
@@ -67,23 +67,15 @@ public class J2ObjcConfiguration extends Fragment {
     }
   }
 
-  private Iterable<String> translationFlags;
-  private String cacheKey;
+  private final Set<String> translationFlags;
+  private final boolean removeDeadCode;
 
-  J2ObjcConfiguration(J2ObjcCommandLineOptions j2ObjcOptions) throws InvalidConfigurationException {
-    Set<String> translationFlags = ImmutableSet.<String>builder()
+  J2ObjcConfiguration(J2ObjcCommandLineOptions j2ObjcOptions) {
+    this.removeDeadCode = j2ObjcOptions.removeDeadCode;
+    this.translationFlags = ImmutableSet.<String>builder()
         .addAll(j2ObjcOptions.translationFlags)
         .addAll(J2OBJC_ALWAYS_ON_TRANSLATION_FLAGS)
         .build();
-
-    if (Collections.disjoint(translationFlags, J2OBJC_BLACKLISTED_TRANSLATION_FLAGS)) {
-      this.translationFlags = translationFlags;
-      this.cacheKey = Joiner.on(" ").join(this.translationFlags);
-    } else {
-      throw new InvalidConfigurationException(String.format(INVALID_TRANSLATION_FLAGS_MSG_TEMPLATE,
-          Joiner.on(",").join(translationFlags),
-          Joiner.on(",").join(J2OBJC_BLACKLISTED_TRANSLATION_FLAGS)));
-    }
   }
 
   /**
@@ -96,6 +88,16 @@ public class J2ObjcConfiguration extends Fragment {
     return translationFlags;
   }
 
+  /**
+   * Returns whether to perform J2ObjC dead code removal. If true, the list of entry classes will be
+   * collected transitively throuh "entry_classes" attribute on j2objc_library and used as entry
+   * points to perform dead code analysis. Unused classes will then be removed from the final ObjC
+   * app bundle.
+   */
+  public boolean removeDeadCode() {
+    return removeDeadCode;
+  }
+
   @Override
   public String getName() {
     return "J2ObjC";
@@ -103,6 +105,16 @@ public class J2ObjcConfiguration extends Fragment {
 
   @Override
   public String cacheKey() {
-    return cacheKey;
+    return Joiner.on(" ").join(translationFlags) + "-" + String.valueOf(removeDeadCode);
+  }
+
+  @Override
+  public void reportInvalidOptions(EventHandler reporter, BuildOptions buildOptions) {
+    if (!Collections.disjoint(translationFlags, J2OBJC_BLACKLISTED_TRANSLATION_FLAGS)) {
+      String errorMsg = String.format(INVALID_TRANSLATION_FLAGS_MSG_TEMPLATE,
+          Joiner.on(",").join(translationFlags),
+          Joiner.on(",").join(J2OBJC_BLACKLISTED_TRANSLATION_FLAGS));
+      reporter.handle(Event.error(errorMsg));
+    }
   }
 }
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/J2ObjcMappingFileProvider.java b/src/main/java/com/google/devtools/build/lib/rules/objc/J2ObjcMappingFileProvider.java
index 7ee799e3df..4714ca2d24 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/J2ObjcMappingFileProvider.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/J2ObjcMappingFileProvider.java
@@ -17,6 +17,7 @@ package com.google.devtools.build.lib.rules.objc;
 import com.google.devtools.build.lib.actions.Artifact;
 import com.google.devtools.build.lib.analysis.TransitiveInfoProvider;
 import com.google.devtools.build.lib.collect.nestedset.NestedSet;
+import com.google.devtools.build.lib.collect.nestedset.NestedSetBuilder;
 import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
 
 /**
@@ -28,11 +29,26 @@ public final class J2ObjcMappingFileProvider implements TransitiveInfoProvider {
 
   private final NestedSet<Artifact> headerMappingFiles;
   private final NestedSet<Artifact> classMappingFiles;
+  private final NestedSet<Artifact> dependencyMappingFiles;
 
+  /**
+   * Constructs a {@link J2ObjcMappingFileProvider} with mapping files to export mappings required
+   * by J2ObjC translation and proto compilation.
+   *
+   * @param headerMappingFiles a nested set of header mapping files which map Java classes to
+   *     their associated translated ObjC header. Used by J2ObjC to output correct import directives
+   *     during translation.
+   * @param classMappingFiles a nested set of class mapping files which map Java class names to
+   *     their associated ObjC class names. Used to support J2ObjC package prefixes.
+   * @param dependencyMappingFiles a nested set of dependency mapping files which map translated
+   *     ObjC files to their translated direct dependency files. Used to support J2ObjC dead code
+   *     analysis and removal.
+   */
   public J2ObjcMappingFileProvider(NestedSet<Artifact> headerMappingFiles,
-      NestedSet<Artifact> classMappingFiles) {
+      NestedSet<Artifact> classMappingFiles, NestedSet<Artifact> dependencyMappingFiles) {
     this.headerMappingFiles = headerMappingFiles;
     this.classMappingFiles = classMappingFiles;
+    this.dependencyMappingFiles = dependencyMappingFiles;
   }
 
   /**
@@ -52,4 +68,36 @@ public final class J2ObjcMappingFileProvider implements TransitiveInfoProvider {
   public NestedSet<Artifact> getClassMappingFiles() {
     return classMappingFiles;
   }
+
+  /**
+   * Returns the mapping files containing file dependency information among the translated ObjC
+   * source files. They are used to strip unused translated files before the compilation and linking
+   * actions at binary level.
+   */
+  public NestedSet<Artifact> getDependencyMappingFiles() {
+    return dependencyMappingFiles;
+  }
+
+  /**
+   * A builder for this provider that is optimized for collection information from transitive
+   * dependencies.
+   */
+  public static final class Builder {
+    private final NestedSetBuilder<Artifact> headerMappingFiles = NestedSetBuilder.stableOrder();
+    private final NestedSetBuilder<Artifact> classMappingFiles = NestedSetBuilder.stableOrder();
+    private final NestedSetBuilder<Artifact> depEntryFiles = NestedSetBuilder.stableOrder();
+
+    public Builder addTransitive(J2ObjcMappingFileProvider provider) {
+      headerMappingFiles.addTransitive(provider.getHeaderMappingFiles());
+      classMappingFiles.addTransitive(provider.getClassMappingFiles());
+      depEntryFiles.addTransitive(provider.getDependencyMappingFiles());
+
+      return this;
+    }
+
+    public J2ObjcMappingFileProvider build() {
+      return new J2ObjcMappingFileProvider(
+          headerMappingFiles.build(), classMappingFiles.build(), depEntryFiles.build());
+    }
+  }
 }
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/J2ObjcSource.java b/src/main/java/com/google/devtools/build/lib/rules/objc/J2ObjcSource.java
index 81ba292314..dc7251ee3a 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/J2ObjcSource.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/J2ObjcSource.java
@@ -15,9 +15,13 @@
 package com.google.devtools.build.lib.rules.objc;
 
 import com.google.common.base.Objects;
+import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Iterators;
 import com.google.devtools.build.lib.actions.Artifact;
+import com.google.devtools.build.lib.analysis.AnalysisUtils;
+import com.google.devtools.build.lib.analysis.RuleContext;
 import com.google.devtools.build.lib.syntax.Label;
+import com.google.devtools.build.lib.vfs.FileSystemUtils;
 import com.google.devtools.build.lib.vfs.PathFragment;
 
 /**
@@ -67,6 +71,41 @@ public class J2ObjcSource {
   }
 
   /**
+   * Returns a corresponding {@link J2ObjcSource} with source artifacts replaced by the outputs of
+   * the J2objC dead code removal script, for use after that action has processed the originals.
+   *
+   * <p>The script in question builds a dependency graph with entry classes specified
+   * transitively on j2objc_library rules as roots. Translated files from this (original)
+   * {@link J2ObjcSource} which are reachable in the graph from the roots will be copied over to the
+   * source file paths in the returned pruned {@link J2ObjcSource} with full original contents.
+   * Unreachable files will not be copied over and the artifacts pointed to by the returned pruned 
+   * {@link J2ObjcSource} will only contain empty files.
+   *
+   * @param ruleContext the {@link RuleContext} of the current rule
+   */
+  public J2ObjcSource toPrunedSource(RuleContext ruleContext) {
+    ImmutableList.Builder<Artifact> prunedSourceArtifacts = ImmutableList.builder();
+
+    for (Artifact sourceArtifact : getObjcSrcs()) {
+      PathFragment scopedPath = AnalysisUtils.getUniqueDirectory(
+          ruleContext.getRule().getLabel(), new PathFragment("_j2objc_pruned"));
+      PathFragment prunedSourceArtifactPath = FileSystemUtils.appendWithoutExtension(
+          scopedPath.getRelative(sourceArtifact.getRootRelativePath()), "_pruned");
+
+      Artifact prunedArtifact = ruleContext.getAnalysisEnvironment().getDerivedArtifact(
+          prunedSourceArtifactPath, ruleContext.getBinOrGenfilesDirectory());
+      prunedSourceArtifacts.add(prunedArtifact);
+    }
+
+    return new J2ObjcSource(
+        getTargetLabel(),
+        prunedSourceArtifacts.build(),
+        getObjcHdrs(),
+        getObjcFilePath(),
+        getSourceType());
+  }
+
+  /**
    * Returns the label of the associated target.
    */
   public Label getTargetLabel() {
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/J2ObjcSrcsProvider.java b/src/main/java/com/google/devtools/build/lib/rules/objc/J2ObjcSrcsProvider.java
index 1e577c5939..4a887ba492 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/J2ObjcSrcsProvider.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/J2ObjcSrcsProvider.java
@@ -14,10 +14,13 @@
 
 package com.google.devtools.build.lib.rules.objc;
 
+import com.google.common.collect.ImmutableSet;
 import com.google.devtools.build.lib.analysis.TransitiveInfoProvider;
 import com.google.devtools.build.lib.collect.nestedset.NestedSet;
 import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
 
+import java.util.Set;
+
 /**
  * This provider is exported by java_library rules to supply J2ObjC-translated ObjC sources to
  * objc_binary for compilation and linking.
@@ -25,10 +28,23 @@ import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
 @Immutable
 public final class J2ObjcSrcsProvider implements TransitiveInfoProvider {
   private final NestedSet<J2ObjcSource> srcs;
+  private final ImmutableSet<String> entryClasses;
   private final boolean hasProtos;
 
-  public J2ObjcSrcsProvider(NestedSet<J2ObjcSource> srcs, boolean hasProtos) {
+  /**
+   * Constructs a {@link J2ObjcSrcsProvider} to supply J2ObjC-translated ObjC sources to
+   * objc_binary for compilation and linking.
+   *
+   * @param srcs a nested set of {@link J2ObjcSource}s containing translated source files
+   * @param entryClasses a set of names of Java classes to used as entry point for J2ObjC dead code
+   *     analysis. The Java class names should be in canonical format as defined by the Java
+   *     Language Specification.
+   * @param hasProtos whether the translated files in this provider have J2ObjC proto files
+   */
+  public J2ObjcSrcsProvider(NestedSet<J2ObjcSource> srcs, ImmutableSet<String> entryClasses,
+      boolean hasProtos) {
     this.srcs = srcs;
+    this.entryClasses = entryClasses;
     this.hasProtos = hasProtos;
   }
 
@@ -37,6 +53,14 @@ public final class J2ObjcSrcsProvider implements TransitiveInfoProvider {
   }
 
   /**
+   * Returns a set of entry classes specified on attribute entry_classes of j2objc_library targets
+   * transitively.
+   */
+  public Set<String> getEntryClasses() {
+    return entryClasses;
+  }
+
+  /**
    * Returns whether the translated source files in the provider has proto files.
    */
   public boolean hasProtos() {
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcBundle.java b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcBundle.java
index 6585cbaf73..7eb806c1a5 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcBundle.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcBundle.java
@@ -46,6 +46,7 @@ public class ObjcBundle implements RuleConfiguredTargetFactory {
         Optional.<XcodeProvider>absent(),
         Optional.of(common.getObjcProvider()),
         Optional.<XcTestAppProvider>absent(),
-        Optional.<J2ObjcSrcsProvider>absent());
+        Optional.<J2ObjcSrcsProvider>absent(),
+        Optional.<J2ObjcMappingFileProvider>absent());
   }
 }
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcBundleLibrary.java b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcBundleLibrary.java
index 4506e6e1ae..fcf9c315b4 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcBundleLibrary.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcBundleLibrary.java
@@ -69,7 +69,8 @@ public class ObjcBundleLibrary implements RuleConfiguredTargetFactory {
         Optional.of(xcodeProviderBuilder.build()),
         Optional.of(nestedBundleProvider),
         Optional.<XcTestAppProvider>absent(),
-        Optional.<J2ObjcSrcsProvider>absent());
+        Optional.<J2ObjcSrcsProvider>absent(),
+        Optional.<J2ObjcMappingFileProvider>absent());
   }
 
   private OptionsProvider optionsProvider(RuleContext ruleContext) {
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcCommon.java b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcCommon.java
index 775a211555..20806aff82 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcCommon.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcCommon.java
@@ -589,7 +589,8 @@ public final class ObjcCommon {
   public RuleConfiguredTargetBuilder configuredTargetBuilder(NestedSet<Artifact> filesToBuild,
       Optional<XcodeProvider> maybeTargetProvider, Optional<ObjcProvider> maybeExportedProvider,
       Optional<XcTestAppProvider> maybeXcTestAppProvider,
-      Optional<J2ObjcSrcsProvider> maybeJ2ObjcSrcsProvider) {
+      Optional<J2ObjcSrcsProvider> maybeJ2ObjcSrcsProvider,
+      Optional<J2ObjcMappingFileProvider> maybeJ2ObjcMappingFileProvider) {
     NestedSet<Artifact> allFilesToBuild = NestedSetBuilder.<Artifact>stableOrder()
         .addTransitive(filesToBuild)
         .build();
@@ -615,6 +616,10 @@ public final class ObjcCommon {
     for (J2ObjcSrcsProvider j2ObjcSrcsProvider : maybeJ2ObjcSrcsProvider.asSet()) {
       target.addProvider(J2ObjcSrcsProvider.class, j2ObjcSrcsProvider);
     }
+    for (J2ObjcMappingFileProvider j2ObjcMappingFileProvider
+        : maybeJ2ObjcMappingFileProvider.asSet()) {
+      target.addProvider(J2ObjcMappingFileProvider.class, j2ObjcMappingFileProvider);
+    }
     return target;
   }
 
@@ -632,8 +637,9 @@ public final class ObjcCommon {
   public ConfiguredTarget configuredTarget(NestedSet<Artifact> filesToBuild,
       Optional<XcodeProvider> maybeTargetProvider, Optional<ObjcProvider> maybeExportedProvider,
       Optional<XcTestAppProvider> maybeXcTestAppProvider,
-      Optional<J2ObjcSrcsProvider> maybeJ2ObjcSrcsProvider) {
+      Optional<J2ObjcSrcsProvider> maybeJ2ObjcSrcsProvider,
+      Optional<J2ObjcMappingFileProvider> maybeJ2ObjcMappingFileProvider) {
     return configuredTargetBuilder(filesToBuild, maybeTargetProvider, maybeExportedProvider,
-        maybeXcTestAppProvider, maybeJ2ObjcSrcsProvider).build();
+        maybeXcTestAppProvider, maybeJ2ObjcSrcsProvider, maybeJ2ObjcMappingFileProvider).build();
   }
 }
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcFramework.java b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcFramework.java
index c6a003757e..5e670f6dd5 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcFramework.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcFramework.java
@@ -55,6 +55,7 @@ public class ObjcFramework implements RuleConfiguredTargetFactory {
         Optional.<XcodeProvider>absent(),
         Optional.of(common.getObjcProvider()),
         Optional.<XcTestAppProvider>absent(),
-        Optional.<J2ObjcSrcsProvider>absent());
+        Optional.<J2ObjcSrcsProvider>absent(),
+        Optional.<J2ObjcMappingFileProvider>absent());
   }
 }
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcImport.java b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcImport.java
index 6c4bf2290a..dc80de46d5 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcImport.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcImport.java
@@ -66,6 +66,7 @@ public class ObjcImport implements RuleConfiguredTargetFactory {
         Optional.of(xcodeProviderBuilder.build()),
         Optional.of(common.getObjcProvider()),
         Optional.<XcTestAppProvider>absent(),
-        Optional.<J2ObjcSrcsProvider>absent());
+        Optional.<J2ObjcSrcsProvider>absent(),
+        Optional.<J2ObjcMappingFileProvider>absent());
   }
 }
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcLibrary.java b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcLibrary.java
index 7d62173376..28c9314d55 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcLibrary.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcLibrary.java
@@ -111,7 +111,8 @@ public class ObjcLibrary implements RuleConfiguredTargetFactory {
         Optional.of(xcodeProviderBuilder.build()),
         Optional.of(common.getObjcProvider()),
         Optional.<XcTestAppProvider>absent(),
-        Optional.of(ObjcRuleClasses.j2ObjcSrcsProvider(ruleContext)));
+        Optional.of(ObjcRuleClasses.j2ObjcSrcsProvider(ruleContext)),
+        Optional.of(ObjcRuleClasses.j2ObjcMappingFileProvider(ruleContext)));
   }
 
   private OptionsProvider optionsProvider(RuleContext ruleContext) {
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcProtoLibrary.java b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcProtoLibrary.java
index c11c7bb213..ae6464dd95 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcProtoLibrary.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcProtoLibrary.java
@@ -215,7 +215,8 @@ public class ObjcProtoLibrary implements RuleConfiguredTargetFactory {
         Optional.of(xcodeProvider),
         Optional.of(common.getObjcProvider()),
         Optional.<XcTestAppProvider>absent(),
-        Optional.<J2ObjcSrcsProvider>absent());
+        Optional.<J2ObjcSrcsProvider>absent(),
+        Optional.<J2ObjcMappingFileProvider>absent());
   }
 
   private NestedSet<Artifact> maybeGetProtoSources(RuleContext ruleContext) {
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcRuleClasses.java b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcRuleClasses.java
index e038039b73..024fbe1211 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcRuleClasses.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcRuleClasses.java
@@ -153,12 +153,14 @@ public class ObjcRuleClasses {
     builder.addAll(currentSource.asSet());
     boolean hasProtos = currentSource.isPresent()
         && currentSource.get().getSourceType() == J2ObjcSource.SourceType.PROTO;
+    ImmutableSet.Builder<String> entryClasses = ImmutableSet.builder();
 
     if (ruleContext.attributes().has("deps", Type.LABEL_LIST)) {
       for (J2ObjcSrcsProvider provider :
           ruleContext.getPrerequisites("deps", Mode.TARGET, J2ObjcSrcsProvider.class)) {
         builder.addTransitive(provider.getSrcs());
         hasProtos |= provider.hasProtos();
+        entryClasses.addAll(provider.getEntryClasses());
       }
     }
 
@@ -167,10 +169,35 @@ public class ObjcRuleClasses {
           ruleContext.getPrerequisites("exports", Mode.TARGET, J2ObjcSrcsProvider.class)) {
         builder.addTransitive(provider.getSrcs());
         hasProtos |= provider.hasProtos();
+        entryClasses.addAll(provider.getEntryClasses());
       }
     }
 
-    return new J2ObjcSrcsProvider(builder.build(), hasProtos);
+    if (ruleContext.attributes().has("entry_classes", Type.STRING_LIST)) {
+      entryClasses.addAll(ruleContext.attributes().get("entry_classes", Type.STRING_LIST));
+    }
+
+    return new J2ObjcSrcsProvider(builder.build(), entryClasses.build(), hasProtos);
+  }
+
+
+  /**
+   * Returns a {@link J2ObjcMappingFileProvider} containing J2ObjC mapping files from rules
+   * that can be reached transitively through the "deps" attribute.
+   *
+   * @param ruleContext the rule context of the current rule
+   * @return a {@link J2ObjcMappingFileProvider} containing J2ObjC mapping files information from
+   *     the transitive closure.
+   */
+  public static J2ObjcMappingFileProvider j2ObjcMappingFileProvider(RuleContext ruleContext) {
+    J2ObjcMappingFileProvider.Builder builder = new J2ObjcMappingFileProvider.Builder();
+    Iterable<J2ObjcMappingFileProvider> providers =
+        ruleContext.getPrerequisites("deps", Mode.TARGET, J2ObjcMappingFileProvider.class);
+    for (J2ObjcMappingFileProvider provider : providers) {
+      builder.addTransitive(provider);
+    }
+
+    return builder.build();
   }
 
   public static Artifact artifactByAppendingToBaseName(RuleContext context, String suffix) {
@@ -669,6 +696,12 @@ public class ObjcRuleClasses {
               return configuration.getFragment(ObjcConfiguration.class).getDumpSymsLabel();
             }
           }))
+          .add(attr("$j2objc_dead_code_pruner", LABEL)
+              .allowedFileTypes(FileType.of(".py"))
+              .cfg(HOST)
+              .exec()
+              .singleArtifact()
+              .value(env.getLabel("//tools/objc:j2objc_dead_code_pruner")))
         .build();
     }
     @Override
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/ReleaseBundlingTargetFactory.java b/src/main/java/com/google/devtools/build/lib/rules/objc/ReleaseBundlingTargetFactory.java
index bdbad39901..b3e27c1363 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/ReleaseBundlingTargetFactory.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/ReleaseBundlingTargetFactory.java
@@ -108,7 +108,8 @@ public abstract class ReleaseBundlingTargetFactory implements RuleConfiguredTarg
         Optional.of(xcodeProviderBuilder.build()),
         exposedObjcProvider,
         Optional.of(releaseBundlingSupport.xcTestAppProvider()),
-        Optional.<J2ObjcSrcsProvider>absent());
+        Optional.<J2ObjcSrcsProvider>absent(),
+        Optional.<J2ObjcMappingFileProvider>absent());
     configureTarget(target, ruleContext, releaseBundlingSupport);
     return target.build();
   }