[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, 15 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/IPO/FunctionImport.cpp b/llvm/lib/Transforms/IPO/FunctionImport.cpp
index 6c571f440b9..3ce3b7b841e 100644
--- a/llvm/lib/Transforms/IPO/FunctionImport.cpp
+++ b/llvm/lib/Transforms/IPO/FunctionImport.cpp
@@ -445,6 +445,21 @@ void llvm::gatherImportedSummariesForModule(
   }
 }
 
+/// Emit the files \p ModulePath will import from into \p OutputFilename.
+std::error_code llvm::EmitImportsFiles(
+    StringRef ModulePath, StringRef OutputFilename,
+    const StringMap<FunctionImporter::ImportMapTy> &ImportLists) {
+  auto ModuleImports = ImportLists.find(ModulePath);
+  std::error_code EC;
+  raw_fd_ostream ImportsOS(OutputFilename, EC, sys::fs::OpenFlags::F_None);
+  if (EC)
+    return EC;
+  if (ModuleImports != ImportLists.end())
+    for (auto &ILI : ModuleImports->second)
+      ImportsOS << ILI.first() << "\n";
+  return std::error_code();
+}
+
 // Automatically import functions in Module \p DestModule based on the summaries
 // index.
 //