[ThinLTO] Add option to emit imports files for distributed backends

Summary:
Add support for emission of plaintext lists of the imported files for
each distributed backend compilation. Used for distributed build file
staging.

Invoked with new gold-plugin thinlto-emit-imports-files option, which is
only valid with thinlto-index-only (i.e. for distributed builds), or
from llvm-lto with new -thinlto-action=emitimports value.

Depends on D19556.

Reviewers: joker.eph

Subscribers: llvm-commits, joker.eph

Differential Revision: http://reviews.llvm.org/D19636

llvm-svn: 269067

1 files changed, 24 insertions, 0 deletions

diff --git a/llvm/lib/LTO/ThinLTOCodeGenerator.cpp b/llvm/lib/LTO/ThinLTOCodeGenerator.cpp
index 68d7a71..93a3f3e 100644
--- a/llvm/lib/LTO/ThinLTOCodeGenerator.cpp
+++ b/llvm/lib/LTO/ThinLTOCodeGenerator.cpp
@@ -743,6 +743,30 @@ void ThinLTOCodeGenerator::gatherImportedSummariesForModule(
 }
 
 /**
+ * Emit the list of files needed for importing into module.
+ */
+void ThinLTOCodeGenerator::emitImports(StringRef ModulePath,
+                                       StringRef OutputName,
+                                       ModuleSummaryIndex &Index) {
+  auto ModuleCount = Index.modulePaths().size();
+
+  // Collect for each module the list of function it defines (GUID -> Summary).
+  StringMap<GVSummaryMapTy> ModuleToDefinedGVSummaries(ModuleCount);
+  Index.collectDefinedGVSummariesPerModule(ModuleToDefinedGVSummaries);
+
+  // Generate import/export list
+  StringMap<FunctionImporter::ImportMapTy> ImportLists(ModuleCount);
+  StringMap<FunctionImporter::ExportSetTy> ExportLists(ModuleCount);
+  ComputeCrossModuleImport(Index, ModuleToDefinedGVSummaries, ImportLists,
+                           ExportLists);
+
+  std::error_code EC;
+  if ((EC = EmitImportsFiles(ModulePath, OutputName, ImportLists)))
+    report_fatal_error(Twine("Failed to open ") + OutputName +
+                       " to save imports lists\n");
+}
+
+/**
  * Perform internalization.
  */
 void ThinLTOCodeGenerator::internalize(Module &TheModule,