[ThinLTO] Fix ThinLTOCodegenerator to export llvm.used symbols

Summary:
ThinLTOCodeGenerator currently does not preserve llvm.used symbols and
it can internalize them. In order to pass the necessary information to the
legacy ThinLTOCodeGenerator, the input to the code generator is
rewritten to be based on lto::InputFile.

This fixes: PR41236
rdar://problem/49293439

Reviewers: tejohnson, pcc, dexonsmith

Reviewed By: tejohnson

Subscribers: mehdi_amini, inglorion, eraman, hiraditya, jkorous, dang, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D60226

llvm-svn: 357931

1 files changed, 52 insertions, 24 deletions

diff --git a/llvm/tools/llvm-lto/llvm-lto.cpp b/llvm/tools/llvm-lto/llvm-lto.cpp
index a71c3dd445c..57a867aa53e 100644
--- a/llvm/tools/llvm-lto/llvm-lto.cpp
+++ b/llvm/tools/llvm-lto/llvm-lto.cpp
@@ -449,22 +449,37 @@ std::unique_ptr<ModuleSummaryIndex> loadCombinedIndex() {
   return ExitOnErr(getModuleSummaryIndexForFile(ThinLTOIndex));
 }
 
-static std::unique_ptr<Module> loadModule(StringRef Filename,
-                                          LLVMContext &Ctx) {
-  SMDiagnostic Err;
-  std::unique_ptr<Module> M(parseIRFile(Filename, Err, Ctx));
-  if (!M) {
-    Err.print("llvm-lto", errs());
-    report_fatal_error("Can't load module for file " + Filename);
-  }
-  maybeVerifyModule(*M);
+static std::unique_ptr<MemoryBuffer> loadFile(StringRef Filename) {
+  ExitOnError ExitOnErr("llvm-lto: error loading file '" + Filename.str() +
+                        "': ");
+  return ExitOnErr(errorOrToExpected(MemoryBuffer::getFileOrSTDIN(Filename)));
+}
 
+static std::unique_ptr<lto::InputFile> loadInputFile(MemoryBufferRef Buffer) {
+  ExitOnError ExitOnErr("llvm-lto: error loading input '" +
+                        Buffer.getBufferIdentifier().str() + "': ");
+  return ExitOnErr(lto::InputFile::create(Buffer));
+}
+
+static std::unique_ptr<Module> loadModuleFromInput(lto::InputFile &File,
+                                                   LLVMContext &CTX) {
+  auto &Mod = File.getSingleBitcodeModule();
+  auto ModuleOrErr = Mod.parseModule(CTX);
+  if (!ModuleOrErr) {
+    handleAllErrors(ModuleOrErr.takeError(), [&](ErrorInfoBase &EIB) {
+      SMDiagnostic Err = SMDiagnostic(Mod.getModuleIdentifier(),
+                                      SourceMgr::DK_Error, EIB.message());
+      Err.print("llvm-lto", errs());
+    });
+    report_fatal_error("Can't load module, abort.");
+  }
+  maybeVerifyModule(**ModuleOrErr);
   if (ThinLTOModuleId.getNumOccurrences()) {
     if (InputFilenames.size() != 1)
       report_fatal_error("Can't override the module id for multiple files");
-    M->setModuleIdentifier(ThinLTOModuleId);
+    (*ModuleOrErr)->setModuleIdentifier(ThinLTOModuleId);
   }
-  return M;
+  return std::move(*ModuleOrErr);
 }
 
 static void writeModuleToFile(Module &TheModule, StringRef Filename) {
@@ -562,13 +577,15 @@ private:
     auto Index = loadCombinedIndex();
     for (auto &Filename : InputFilenames) {
       LLVMContext Ctx;
-      auto TheModule = loadModule(Filename, Ctx);
+      auto Buffer = loadFile(Filename);
+      auto Input = loadInputFile(Buffer->getMemBufferRef());
+      auto TheModule = loadModuleFromInput(*Input, Ctx);
 
       // Build a map of module to the GUIDs and summary objects that should
       // be written to its index.
       std::map<std::string, GVSummaryMapTy> ModuleToSummariesForIndex;
-      ThinGenerator.gatherImportedSummariesForModule(*TheModule, *Index,
-                                                     ModuleToSummariesForIndex);
+      ThinGenerator.gatherImportedSummariesForModule(
+          *TheModule, *Index, ModuleToSummariesForIndex, *Input);
 
       std::string OutputName = OutputFilename;
       if (OutputName.empty()) {
@@ -597,13 +614,16 @@ private:
     auto Index = loadCombinedIndex();
     for (auto &Filename : InputFilenames) {
       LLVMContext Ctx;
-      auto TheModule = loadModule(Filename, Ctx);
+      auto Buffer = loadFile(Filename);
+      auto Input = loadInputFile(Buffer->getMemBufferRef());
+      auto TheModule = loadModuleFromInput(*Input, Ctx);
       std::string OutputName = OutputFilename;
       if (OutputName.empty()) {
         OutputName = Filename + ".imports";
       }
-      OutputName = getThinLTOOutputFile(OutputName, OldPrefix, NewPrefix);
-      ThinGenerator.emitImports(*TheModule, OutputName, *Index);
+      OutputName =
+          getThinLTOOutputFile(OutputName, OldPrefix, NewPrefix);
+      ThinGenerator.emitImports(*TheModule, OutputName, *Index, *Input);
     }
   }
 
@@ -621,9 +641,11 @@ private:
     auto Index = loadCombinedIndex();
     for (auto &Filename : InputFilenames) {
       LLVMContext Ctx;
-      auto TheModule = loadModule(Filename, Ctx);
+      auto Buffer = loadFile(Filename);
+      auto Input = loadInputFile(Buffer->getMemBufferRef());
+      auto TheModule = loadModuleFromInput(*Input, Ctx);
 
-      ThinGenerator.promote(*TheModule, *Index);
+      ThinGenerator.promote(*TheModule, *Index, *Input);
 
       std::string OutputName = OutputFilename;
       if (OutputName.empty()) {
@@ -652,9 +674,11 @@ private:
 
     for (auto &Filename : InputFilenames) {
       LLVMContext Ctx;
-      auto TheModule = loadModule(Filename, Ctx);
+      auto Buffer = loadFile(Filename);
+      auto Input = loadInputFile(Buffer->getMemBufferRef());
+      auto TheModule = loadModuleFromInput(*Input, Ctx);
 
-      ThinGenerator.crossModuleImport(*TheModule, *Index);
+      ThinGenerator.crossModuleImport(*TheModule, *Index, *Input);
 
       std::string OutputName = OutputFilename;
       if (OutputName.empty()) {
@@ -683,9 +707,11 @@ private:
 
     for (auto &Filename : InputFilenames) {
       LLVMContext Ctx;
-      auto TheModule = loadModule(Filename, Ctx);
+      auto Buffer = loadFile(Filename);
+      auto Input = loadInputFile(Buffer->getMemBufferRef());
+      auto TheModule = loadModuleFromInput(*Input, Ctx);
 
-      ThinGenerator.internalize(*TheModule, *Index);
+      ThinGenerator.internalize(*TheModule, *Index, *Input);
 
       std::string OutputName = OutputFilename;
       if (OutputName.empty()) {
@@ -706,7 +732,9 @@ private:
 
     for (auto &Filename : InputFilenames) {
       LLVMContext Ctx;
-      auto TheModule = loadModule(Filename, Ctx);
+      auto Buffer = loadFile(Filename);
+      auto Input = loadInputFile(Buffer->getMemBufferRef());
+      auto TheModule = loadModuleFromInput(*Input, Ctx);
 
       ThinGenerator.optimize(*TheModule);