Collect .o files compiled from C(++), and skip the rest for the LTO backend step.

This should make ThinLTO work with .o files that are not generated by
compiling C++ in a cc_library()

--
MOS_MIGRATED_REVID=104764111

9 files changed, 169 insertions, 54 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/CcBinary.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/CcBinary.java
index 6fb4a6dc74..3786fcc1a9 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/CcBinary.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/CcBinary.java
@@ -343,14 +343,15 @@ public abstract class CcBinary implements RuleConfiguredTargetFactory {
 
     // Determine the object files to link in.
     boolean usePic = CppHelper.usePic(context, !isLinkShared(context));
-    Iterable<Artifact> compiledObjectFiles = compilationOutputs.getObjectFiles(usePic);
+    Iterable<Artifact> objectFiles = compilationOutputs.getObjectFiles(usePic);
 
     if (fake) {
-      builder.addFakeNonLibraryInputs(compiledObjectFiles);
+      builder.addFakeNonLibraryInputs(objectFiles);
     } else {
-      builder.addNonLibraryInputs(compiledObjectFiles);
+      builder.addNonLibraryInputs(objectFiles);
     }
 
+    builder.addLTOBitcodeFiles(compilationOutputs.getLtoBitcodeFiles());
     builder.addNonLibraryInputs(common.getLinkerScripts());
 
     // Determine the libraries to link in.
diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/CcCompilationOutputs.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/CcCompilationOutputs.java
index f7ff4d8227..67162c20d7 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/CcCompilationOutputs.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/CcCompilationOutputs.java
@@ -40,6 +40,11 @@ public class CcCompilationOutputs {
   private final ImmutableList<Artifact> picObjectFiles;
 
   /**
+   * All .o files coming from a C(++) compilation under our control.
+   */
+  private final ImmutableList<Artifact> ltoBitcodeFiles;
+
+  /**
    * All .dwo files built by the target, corresponding to .o outputs.
    */
   private final ImmutableList<Artifact> dwoFiles;
@@ -61,13 +66,19 @@ public class CcCompilationOutputs {
 
   private final List<IncludeScannable> lipoScannables;
 
-  private CcCompilationOutputs(ImmutableList<Artifact> objectFiles,
-      ImmutableList<Artifact> picObjectFiles, ImmutableList<Artifact> dwoFiles,
-      ImmutableList<Artifact> picDwoFiles, NestedSet<Artifact> temps,
+  private CcCompilationOutputs(
+      ImmutableList<Artifact> objectFiles,
+      ImmutableList<Artifact> picObjectFiles,
+      ImmutableList<Artifact> ltoBitcodeFiles,
+
+      ImmutableList<Artifact> dwoFiles,
+      ImmutableList<Artifact> picDwoFiles,
+      NestedSet<Artifact> temps,
       ImmutableList<Artifact> headerTokenFiles,
       ImmutableList<IncludeScannable> lipoScannables) {
     this.objectFiles = objectFiles;
     this.picObjectFiles = picObjectFiles;
+    this.ltoBitcodeFiles = ltoBitcodeFiles;
     this.dwoFiles = dwoFiles;
     this.picDwoFiles = picDwoFiles;
     this.temps = temps;
@@ -92,6 +103,13 @@ public class CcCompilationOutputs {
   }
 
   /**
+   * Returns unmodifiable view of object files resulting from compilation.
+   */
+  public ImmutableList<Artifact> getLtoBitcodeFiles() {
+    return ltoBitcodeFiles;
+  }
+
+  /**
    * Returns an unmodifiable view of the .dwo files set.
    */
   public ImmutableList<Artifact> getDwoFiles() {
@@ -130,6 +148,7 @@ public class CcCompilationOutputs {
   public static final class Builder {
     private final Set<Artifact> objectFiles = new LinkedHashSet<>();
     private final Set<Artifact> picObjectFiles = new LinkedHashSet<>();
+    private final Set<Artifact> ltoBitcodeFiles = new LinkedHashSet<>();
     private final Set<Artifact> dwoFiles = new LinkedHashSet<>();
     private final Set<Artifact> picDwoFiles = new LinkedHashSet<>();
     private final NestedSetBuilder<Artifact> temps = NestedSetBuilder.stableOrder();
@@ -137,9 +156,13 @@ public class CcCompilationOutputs {
     private final List<IncludeScannable> lipoScannables = new ArrayList<>();
 
     public CcCompilationOutputs build() {
-      return new CcCompilationOutputs(ImmutableList.copyOf(objectFiles),
-          ImmutableList.copyOf(picObjectFiles), ImmutableList.copyOf(dwoFiles),
-          ImmutableList.copyOf(picDwoFiles), temps.build(),
+      return new CcCompilationOutputs(
+          ImmutableList.copyOf(objectFiles),
+          ImmutableList.copyOf(picObjectFiles),
+          ImmutableList.copyOf(ltoBitcodeFiles),
+          ImmutableList.copyOf(dwoFiles),
+          ImmutableList.copyOf(picDwoFiles),
+          temps.build(),
           ImmutableList.copyOf(headerTokenFiles),
           ImmutableList.copyOf(lipoScannables));
     }
@@ -176,6 +199,16 @@ public class CcCompilationOutputs {
       return this;
     }
 
+    public Builder addLTOBitcodeFile(Artifact a) {
+      ltoBitcodeFiles.add(a);
+      return this;
+    }
+
+    public Builder addLTOBitcodeFile(Iterable<Artifact> artifacts) {
+      Iterables.addAll(ltoBitcodeFiles, artifacts);
+      return this;
+    }
+
     public Builder addPicObjectFiles(Iterable<Artifact> artifacts) {
       Iterables.addAll(picObjectFiles, artifacts);
       return this;
diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/CcLibraryHelper.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/CcLibraryHelper.java
index ac06521f8c..8ff2114b92 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/CcLibraryHelper.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/CcLibraryHelper.java
@@ -648,11 +648,13 @@ public final class CcLibraryHelper {
     CcCompilationOutputs ccOutputs = model.createCcCompileActions();
     if (!objectFiles.isEmpty() || !picObjectFiles.isEmpty()) {
       // Merge the pre-compiled object files into the compiler outputs.
-      ccOutputs = new CcCompilationOutputs.Builder()
-          .merge(ccOutputs)
-          .addObjectFiles(objectFiles)
-          .addPicObjectFiles(picObjectFiles)
-          .build();
+      ccOutputs =
+          new CcCompilationOutputs.Builder()
+              .merge(ccOutputs)
+              .addLTOBitcodeFile(ccOutputs.getLtoBitcodeFiles())
+              .addObjectFiles(objectFiles)
+              .addPicObjectFiles(picObjectFiles)
+              .build();
     }
 
     // Create link actions (only if there are object files or if explicitly requested).
diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppFileTypes.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppFileTypes.java
index 7574839d3d..478759ab34 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppFileTypes.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppFileTypes.java
@@ -15,6 +15,7 @@ package com.google.devtools.build.lib.rules.cpp;
 
 import com.google.common.collect.ImmutableList;
 import com.google.devtools.build.lib.util.FileType;
+import com.google.devtools.build.lib.util.FileTypeSet;
 
 import java.util.List;
 import java.util.regex.Pattern;
@@ -25,6 +26,11 @@ import java.util.regex.Pattern;
 public final class CppFileTypes {
   public static final FileType CPP_SOURCE = FileType.of(".cc", ".cpp", ".cxx", ".c++", ".C");
   public static final FileType C_SOURCE = FileType.of(".c");
+
+  // Filetypes that generate LLVM bitcode when -flto is specified.
+  public static final FileTypeSet LTO_SOURCE =
+      FileTypeSet.of(CppFileTypes.CPP_SOURCE, CppFileTypes.C_SOURCE);
+
   public static final FileType CPP_HEADER = FileType.of(".h", ".hh", ".hpp", ".hxx", ".inc");
   public static final FileType CPP_TEXTUAL_INCLUDE = FileType.of(".inc");
 
diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppLinkAction.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppLinkAction.java
index d11fd3c3aa..4d412e983c 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppLinkAction.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppLinkAction.java
@@ -64,6 +64,7 @@ import com.google.devtools.build.lib.vfs.PathFragment;
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Collection;
+import java.util.HashMap;
 import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Map;
@@ -517,7 +518,6 @@ public final class CppLinkAction extends AbstractAction {
     private final AnalysisEnvironment analysisEnvironment;
     private final Artifact output;
 
-    @Nullable private PathFragment interfaceOutputPath;
     // can be null for CppLinkAction.createTestBuilder()
     @Nullable private final CcToolchainProvider toolchain;
     private Artifact interfaceOutput;
@@ -539,6 +539,8 @@ public final class CppLinkAction extends AbstractAction {
     private final List<String> linkopts = new ArrayList<>();
     private LinkTargetType linkType = LinkTargetType.STATIC_LIBRARY;
     private LinkStaticness linkStaticness = LinkStaticness.FULLY_STATIC;
+    private List<Artifact> ltoBitcodeFiles = new ArrayList<>();
+
     private boolean fake;
     private boolean isNativeDeps;
     private boolean useTestOnlyFlags;
@@ -631,11 +633,20 @@ public final class CppLinkAction extends AbstractAction {
 
     private Iterable<LTOBackendArtifacts> createLTOArtifacts(
         PathFragment ltoOutputRootPrefix, NestedSet<LibraryToLink> uniqueLibraries) {
+      Set<Artifact> compiled = new LinkedHashSet<>();
+      for (LibraryToLink lib : uniqueLibraries) {
+        Iterables.addAll(compiled, lib.getLTOBitcodeFiles());
+      }
+
       // This flattens the set of object files, so for M binaries and N .o files,
       // this is O(M*N). If we had a nested set of .o files, we could have O(M + N) instead.
       NestedSetBuilder<Artifact> bitcodeBuilder = NestedSetBuilder.stableOrder();
       for (LibraryToLink lib : uniqueLibraries) {
-        bitcodeBuilder.addAll(lib.getObjectFiles());
+        for (Artifact a : lib.getObjectFiles()) {
+          if (compiled.contains(a)) {
+            bitcodeBuilder.add(a);
+          }
+        }
       }
       for (LinkerInput input : nonLibraries) {
         // This relies on file naming conventions. It would be less fragile to have a dedicated
@@ -712,11 +723,12 @@ public final class CppLinkAction extends AbstractAction {
           : ruleContext.getFeatures();
 
       final LibraryToLink outputLibrary =
-          LinkerInputs.newInputLibrary(output, filteredNonLibraryArtifacts);
+          LinkerInputs.newInputLibrary(output, filteredNonLibraryArtifacts, this.ltoBitcodeFiles);
       final LibraryToLink interfaceOutputLibrary =
           (interfaceOutput == null)
               ? null
-              : LinkerInputs.newInputLibrary(interfaceOutput, filteredNonLibraryArtifacts);
+              : LinkerInputs.newInputLibrary(
+                  interfaceOutput, filteredNonLibraryArtifacts, this.ltoBitcodeFiles);
 
       final ImmutableMap<Artifact, Artifact> linkstampMap =
           mapLinkstampsToOutputs(linkstamps, ruleContext, output, linkArtifactFactory);
@@ -815,22 +827,39 @@ public final class CppLinkAction extends AbstractAction {
           LinkerInputs.toLibraryArtifacts(
               Link.mergeInputsDependencies(
                   uniqueLibraries, needWholeArchive, cppConfiguration.archiveType()));
-
+      Iterable<Artifact> expandedNonLibraryInputs = LinkerInputs.toLibraryArtifacts(nonLibraries);
       if (!isLTOIndexing && allLTOArtifacts != null) {
-        // This is the real link, rename the inputs.
-        List<Artifact> renamed = new ArrayList<>();
+        // We are doing LTO, and this is the real link, so substitute
+        // the LTO bitcode files with the real object files they were translated into.
+        Map<Artifact, Artifact> ltoMapping = new HashMap<>();
         for (LTOBackendArtifacts a : allLTOArtifacts) {
-          renamed.add(a.getObjectFile());
+          ltoMapping.put(a.getBitcodeFile(), a.getObjectFile());
+        }
+
+        // Handle libraries.
+        List<Artifact> renamedInputs = new ArrayList<>();
+        for (Artifact a : expandedInputs) {
+          Artifact renamed = ltoMapping.get(a);
+          renamedInputs.add(renamed == null ? a : renamed);
+        }
+        expandedInputs = renamedInputs;
+
+        // Handle non-libraries.
+        List<Artifact> renamedNonLibraryInputs = new ArrayList<>();
+        for (Artifact a : expandedNonLibraryInputs) {
+          Artifact renamed = ltoMapping.get(a);
+          renamedNonLibraryInputs.add(renamed == null ? a : renamed);
         }
-        expandedInputs = renamed;
+        expandedNonLibraryInputs = renamedNonLibraryInputs;
       }
 
       // getPrimaryInput returns the first element, and that is a public interface - therefore the
       // order here is important.
-      IterablesChain.Builder<Artifact> inputsBuilder = IterablesChain.<Artifact>builder()
-          .add(ImmutableList.copyOf(LinkerInputs.toLibraryArtifacts(nonLibraries)))
-          .add(dependencyInputsBuilder.build())
-          .add(ImmutableIterable.from(expandedInputs));
+      IterablesChain.Builder<Artifact> inputsBuilder =
+          IterablesChain.<Artifact>builder()
+              .add(ImmutableList.copyOf(expandedNonLibraryInputs))
+              .add(dependencyInputsBuilder.build())
+              .add(ImmutableIterable.from(expandedInputs));
 
       if (linkCommandLine.getParamFile() != null) {
         inputsBuilder.add(ImmutableList.of(linkCommandLine.getParamFile()));
@@ -989,6 +1018,13 @@ public final class CppLinkAction extends AbstractAction {
       this.nonLibraries.add(input);
     }
 
+    public Builder addLTOBitcodeFiles(Iterable<Artifact> files) {
+      for (Artifact a : files) {
+        ltoBitcodeFiles.add(a);
+      }
+      return this;
+    }
+
     /**
      * Adds a single artifact to the set of inputs (C++ source files, header files, etc). Artifacts
      * that are not of recognized types will be used for dependency checking but will not be passed
diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppModel.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppModel.java
index 262dd3794e..fdb0b348a0 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppModel.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppModel.java
@@ -484,7 +484,12 @@ public final class CppModel {
         CppCompileAction picAction = picBuilder.build();
         env.registerAction(picAction);
         if (addObject) {
-          result.addPicObjectFile(picAction.getOutputFile());          
+          result.addPicObjectFile(picAction.getOutputFile());
+
+          if (featureConfiguration.isEnabled(CppRuleClasses.THIN_LTO)
+              && CppFileTypes.LTO_SOURCE.matches(sourceArtifact.getFilename())) {
+            result.addLTOBitcodeFile(picAction.getOutputFile());
+          }
         }
         if (picAction.getDwoFile() != null) {
           // Host targets don't produce .dwo files.
@@ -511,8 +516,12 @@ public final class CppModel {
 
         if (maySaveTemps) {
           result.addTemps(
-              createTempsActions(sourceArtifact, outputName, builder, /*usePic=*/false,
-                ccRelativeName));
+              createTempsActions(
+                  sourceArtifact,
+                  outputName,
+                  builder,
+                  /*usePic=*/ false,
+                  ccRelativeName));
         }
 
         semantics.finalizeCompileActionBuilder(ruleContext, builder);
@@ -521,6 +530,10 @@ public final class CppModel {
         Artifact objectFile = compileAction.getOutputFile();
         if (addObject) {
           result.addObjectFile(objectFile);
+          if (featureConfiguration.isEnabled(CppRuleClasses.THIN_LTO)
+              && CppFileTypes.LTO_SOURCE.matches(sourceArtifact.getFilename())) {
+            result.addLTOBitcodeFile(objectFile);
+          }
         }
         if (compileAction.getDwoFile() != null) {
           // Host targets don't produce .dwo files.
@@ -603,12 +616,14 @@ public final class CppModel {
     // Presumably, it is done this way because the .a file is an implicit output of every cc_library
     // rule, so we can't use ".pic.a" that in the always-PIC case.
     Artifact linkedArtifact = CppHelper.getLinkedArtifact(ruleContext, linkType);
-    CppLinkAction maybePicAction = newLinkActionBuilder(linkedArtifact)
-        .addNonLibraryInputs(ccOutputs.getObjectFiles(usePicForBinaries))
-        .addNonLibraryInputs(ccOutputs.getHeaderTokenFiles())
-        .setLinkType(linkType)
-        .setLinkStaticness(LinkStaticness.FULLY_STATIC)
-        .build();
+    CppLinkAction maybePicAction =
+        newLinkActionBuilder(linkedArtifact)
+            .addNonLibraryInputs(ccOutputs.getObjectFiles(usePicForBinaries))
+            .addNonLibraryInputs(ccOutputs.getHeaderTokenFiles())
+            .addLTOBitcodeFiles(ccOutputs.getLtoBitcodeFiles())
+            .setLinkType(linkType)
+            .setLinkStaticness(LinkStaticness.FULLY_STATIC)
+            .build();
     env.registerAction(maybePicAction);
     result.addStaticLibrary(maybePicAction.getOutputLibrary());
 
@@ -621,12 +636,14 @@ public final class CppModel {
           : LinkTargetType.PIC_STATIC_LIBRARY;
 
       Artifact picArtifact = CppHelper.getLinkedArtifact(ruleContext, picLinkType);
-      CppLinkAction picAction = newLinkActionBuilder(picArtifact)
-          .addNonLibraryInputs(ccOutputs.getObjectFiles(true))
-          .addNonLibraryInputs(ccOutputs.getHeaderTokenFiles())
-          .setLinkType(picLinkType)
-          .setLinkStaticness(LinkStaticness.FULLY_STATIC)
-          .build();
+      CppLinkAction picAction =
+          newLinkActionBuilder(picArtifact)
+              .addNonLibraryInputs(ccOutputs.getObjectFiles(true))
+              .addNonLibraryInputs(ccOutputs.getHeaderTokenFiles())
+              .addLTOBitcodeFiles(ccOutputs.getLtoBitcodeFiles())
+              .setLinkType(picLinkType)
+              .setLinkStaticness(LinkStaticness.FULLY_STATIC)
+              .build();
       env.registerAction(picAction);
       result.addPicStaticLibrary(picAction.getOutputLibrary());
     }
diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/LTOBackendArtifacts.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/LTOBackendArtifacts.java
index eb135726d8..78ee47bf9f 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/LTOBackendArtifacts.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/LTOBackendArtifacts.java
@@ -120,7 +120,7 @@ public final class LTOBackendArtifacts {
     builder.addTransitiveInputs(CppHelper.getToolchain(ruleContext).getLink());
     builder.addOutput(objectFile);
 
-    builder.setProgressMessage("LTO Backend Compile");
+    builder.setProgressMessage("LTO Backend Compile " + objectFile.getFilename());
     builder.setMnemonic("CcLtoBackendCompile");
 
     // The command-line doesn't specify the full path to clang++, so we set it in the
diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/LinkCommandLine.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/LinkCommandLine.java
index b46cca78c0..64f779173d 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/LinkCommandLine.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/LinkCommandLine.java
@@ -938,15 +938,15 @@ public final class LinkCommandLine extends CommandLine {
           if (ltoMap != null) {
             Artifact backend = ltoMap.remove(member);
 
-            if (backend == null) {
-              System.err.println(
-                  "LTO backend file missing for " + member + " already did: " + options);
-              backend = member;
+            if (backend != null) {
+              // If the backend artifact is missing, we can't print a warning because this may
+              // happen normally, due libraries that list .o files explicitly, or generate .o
+              // files from assembler.
+              member = backend;
             }
-            options.add(backend.getExecPathString());
-          } else {
-            options.add(member.getExecPathString());
           }
+
+          options.add(member.getExecPathString());
         }
         options.add("-Wl,--end-lib");
       }
diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/LinkerInputs.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/LinkerInputs.java
index e3875be2c1..21e4146c63 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/LinkerInputs.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/LinkerInputs.java
@@ -16,6 +16,7 @@ package com.google.devtools.build.lib.rules.cpp;
 
 import com.google.common.base.Function;
 import com.google.common.base.Preconditions;
+import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Iterables;
 import com.google.devtools.build.lib.actions.Artifact;
 import com.google.devtools.build.lib.collect.CollectionUtils;
@@ -113,6 +114,8 @@ public abstract class LinkerInputs {
      * Returns whether the library is a solib symlink.
      */
     boolean isSolibSymlink();
+
+    Iterable<Artifact> getLTOBitcodeFiles();
   }
 
   /**
@@ -146,6 +149,11 @@ public abstract class LinkerInputs {
     }
 
     @Override
+    public Iterable<Artifact> getLTOBitcodeFiles() {
+      return ImmutableList.<Artifact>of();
+    }
+
+    @Override
     public boolean isFake() {
       return false;
     }
@@ -195,10 +203,16 @@ public abstract class LinkerInputs {
   private static class CompoundLibraryToLink implements LibraryToLink {
     private final Artifact libraryArtifact;
     private final Iterable<Artifact> objectFiles;
+    private final Iterable<Artifact> ltoBitcodeFiles;
 
-    private CompoundLibraryToLink(Artifact libraryArtifact, Iterable<Artifact> objectFiles) {
+    private CompoundLibraryToLink(
+        Artifact libraryArtifact,
+        Iterable<Artifact> objectFiles,
+        Iterable<Artifact> ltoBitcodeFiles) {
       this.libraryArtifact = Preconditions.checkNotNull(libraryArtifact);
       this.objectFiles = objectFiles == null ? null : CollectionUtils.makeImmutable(objectFiles);
+      this.ltoBitcodeFiles =
+          (ltoBitcodeFiles == null) ? null : CollectionUtils.makeImmutable(ltoBitcodeFiles);
     }
 
     @Override
@@ -233,6 +247,11 @@ public abstract class LinkerInputs {
     }
 
     @Override
+    public Iterable<Artifact> getLTOBitcodeFiles() {
+      return ltoBitcodeFiles;
+    }
+
+    @Override
     public boolean equals(Object that) {
       if (this == that) {
         return true;
@@ -318,14 +337,15 @@ public abstract class LinkerInputs {
     // Preconditions.checkArgument(
     //     !(artifact.getGeneratingAction() instanceof CppLinkAction) ||
     //     !Link.ARCHIVE_LIBRARY_FILETYPES.contains(artifact.getFileType()));
-    return new CompoundLibraryToLink(artifact, null);
+    return new CompoundLibraryToLink(artifact, null, null);
   }
 
   /**
    * Creates a library to link with the specified object files.
    */
-  public static LibraryToLink newInputLibrary(Artifact library, Iterable<Artifact> objectFiles) {
-    return new CompoundLibraryToLink(library, objectFiles);
+  public static LibraryToLink newInputLibrary(
+      Artifact library, Iterable<Artifact> objectFiles, Iterable<Artifact> ltoBitcodeFiles) {
+    return new CompoundLibraryToLink(library, objectFiles, ltoBitcodeFiles);
   }
 
   private static final Function<LibraryToLink, Artifact> LIBRARY_TO_NON_SOLIB =