Frontend: Adopt llvm::vfs::OutputBackend in CompilerInstance

[steven_wu]

Summary

Adopt new virtual output backend in CompilerInstance.

clang/include/clang/Frontend/CompilerInstance.h

 #include "clang/Lex/HeaderSearchOptions.h"
 #include "clang/Lex/ModuleLoader.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/IntrusiveRefCntPtr.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/BuryPointer.h"
 #include "llvm/Support/FileSystem.h"
+#include "llvm/Support/VirtualOutputBackend.h"
 #include <cassert>
 #include <list>
 #include <memory>
 #include <string>
 #include <utility>
 
 namespace llvm {
 class raw_fd_ostream;
class CompilerInstance : public ModuleLoader {
   IntrusiveRefCntPtr<TargetInfo> Target;
 
   /// Auxiliary Target info.
   IntrusiveRefCntPtr<TargetInfo> AuxTarget;
 
   /// The file manager.
   IntrusiveRefCntPtr<FileManager> FileMgr;
 
+  /// The output backend.
+  IntrusiveRefCntPtr<llvm::vfs::OutputBackend> TheOutputBackend;
+
   /// The source manager.
   IntrusiveRefCntPtr<SourceManager> SourceMgr;
 
   /// The cache of PCM files.
   IntrusiveRefCntPtr<InMemoryModuleCache> ModuleCache;
 
   /// The preprocessor.
   std::shared_ptr<Preprocessor> PP;
class CompilerInstance : public ModuleLoader {
   bool DisableGeneratingGlobalModuleIndex = false;
 
   /// The stream for verbose output if owned, otherwise nullptr.
   std::unique_ptr<raw_ostream> OwnedVerboseOutputStream;
 
   /// The stream for verbose output.
   raw_ostream *VerboseOutputStream = &llvm::errs();
 
-  /// Holds information about the output file.
-  ///
-  /// If TempFilename is not empty we must rename it to Filename at the end.
-  /// TempFilename may be empty and Filename non-empty if creating the temporary
-  /// failed.
-  struct OutputFile {
-    std::string Filename;
-    Optional<llvm::sys::fs::TempFile> File;
-
-    OutputFile(std::string filename, Optional<llvm::sys::fs::TempFile> file)
-        : Filename(std::move(filename)), File(std::move(file)) {}
-  };
-
   /// The list of active output files.
-  std::list<OutputFile> OutputFiles;
+  std::list<llvm::vfs::OutputFile> OutputFiles;
 
   /// Force an output buffer.
   std::unique_ptr<llvm::raw_pwrite_stream> OutputStream;
 
   CompilerInstance(const CompilerInstance &) = delete;
   void operator=(const CompilerInstance &) = delete;
 public:
   explicit CompilerInstance(
void resetAndLeakFileManager() {
     llvm::BuryPointer(FileMgr.get());
     FileMgr.resetWithoutRelease();
   }
 
   /// Replace the current file manager and virtual file system.
   void setFileManager(FileManager *Value);
 
   /// }
+  /// @name Output Backend.
+  /// {
+
+  /// Set the output backend.
+  void
+  setOutputBackend(IntrusiveRefCntPtr<llvm::vfs::OutputBackend> NewOutputs);
+
+  /// Create an output manager.
+  void createOutputBackend();
+
+  bool hasOutputBackend() const { return bool(TheOutputBackend); }
+
+  llvm::vfs::OutputBackend &getOutputBackend();
+  llvm::vfs::OutputBackend &getOrCreateOutputBackend();
+
+  /// }
   /// @name Source Manager
   /// {
 
   bool hasSourceManager() const { return SourceMgr != nullptr; }
 
   /// Return the current source manager.
   SourceManager &getSourceManager() const {
     assert(SourceMgr && "Compiler instance has no source manager!");

clang/lib/Frontend/CompilerInstance.cpp

 #include "llvm/Support/Host.h"
 #include "llvm/Support/LockFileManager.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/Program.h"
 #include "llvm/Support/Signals.h"
 #include "llvm/Support/TimeProfiler.h"
 #include "llvm/Support/Timer.h"
+#include "llvm/Support/VirtualOutputBackends.h"
 #include "llvm/Support/raw_ostream.h"
 #include <time.h>
 #include <utility>
 
 using namespace clang;
 
 CompilerInstance::CompilerInstance(
     std::shared_ptr<PCHContainerOperations> PCHContainerOps,
void CompilerInstance::createPreprocessor(TranslationUnitKind TUKind) {
   // and also (a) collect header maps and (b) TODO: input vfs overlay files.
   if (ModuleDepCollector) {
     addDependencyCollector(ModuleDepCollector);
     collectHeaderMaps(PP->getHeaderSearchInfo(), ModuleDepCollector);
     collectIncludePCH(*this, ModuleDepCollector);
     collectVFSEntries(*this, ModuleDepCollector);
   }
 
+  // Modules need an output manager.
+  if (!hasOutputBackend())
+    createOutputBackend();
+
   for (auto &Listener : DependencyCollectors)
     Listener->attachToPreprocessor(*PP);
 
   // Handle generating header include information, if requested.
   if (DepOpts.ShowHeaderIncludes)
     AttachHeaderIncludeGen(*PP, DepOpts);
   if (!DepOpts.HeaderIncludeOutputFile.empty()) {
     StringRef OutputPath = DepOpts.HeaderIncludeOutputFile;

 }
 
 // Output Files
 
 void CompilerInstance::clearOutputFiles(bool EraseFiles) {
   // The ASTConsumer can own streams that write to the output files.
   assert(!hasASTConsumer() && "ASTConsumer should be reset");
   // Ignore errors that occur when trying to discard the temp file.
-  for (OutputFile &OF : OutputFiles) {
-    if (EraseFiles) {
-      if (OF.File)
-        consumeError(OF.File->discard());
-      if (!OF.Filename.empty())
-        llvm::sys::fs::remove(OF.Filename);
-      continue;
-    }
-
-    if (!OF.File)
-      continue;
-
-    if (OF.File->TmpName.empty()) {
-      consumeError(OF.File->discard());
-      continue;
-    }
-
-    // If '-working-directory' was passed, the output filename should be
-    // relative to that.
-    SmallString<128> NewOutFile(OF.Filename);
-    FileMgr->FixupRelativePath(NewOutFile);
-
-    llvm::Error E = OF.File->keep(NewOutFile);
-    if (!E)
-      continue;
-
+  if (!EraseFiles) {
+    for (auto &O : OutputFiles)
+      llvm::handleAllErrors(
+          O.keep(),
+          [&](const llvm::vfs::TempFileOutputError &E) {
             getDiagnostics().Report(diag::err_unable_to_rename_temp)
-        << OF.File->TmpName << OF.Filename << std::move(E);
-
-    llvm::sys::fs::remove(OF.File->TmpName);
+                << E.getTempPath() << E.getOutputPath()
+                << E.convertToErrorCode().message();
+          },
+          [&](const llvm::vfs::OutputError &E) {
+            getDiagnostics().Report(diag::err_fe_unable_to_open_output)
+                << E.getOutputPath() << E.convertToErrorCode().message();
+          });
   }
   OutputFiles.clear();
   if (DeleteBuiltModules) {
     for (auto &Module : BuiltModules)
       llvm::sys::fs::remove(Module.second);
     BuiltModules.clear();
   }
 }
return createOutputFile(OutputPath, Binary, RemoveFileOnSignal,
                           getFrontendOpts().UseTemporary || ForceUseTemporary,
                           CreateMissingDirectories);
 }
 
 std::unique_ptr<raw_pwrite_stream> CompilerInstance::createNullOutputFile() {
   return std::make_unique<llvm::raw_null_ostream>();
 }
 
+void CompilerInstance::setOutputBackend(
+    IntrusiveRefCntPtr<llvm::vfs::OutputBackend> NewOutputs) {
+  assert(!TheOutputBackend && "Already has an output manager");
+  TheOutputBackend = std::move(NewOutputs);
+}
+
+void CompilerInstance::createOutputBackend() {
+  assert(!TheOutputBackend && "Already has an output manager");
+  TheOutputBackend =
+      llvm::makeIntrusiveRefCnt<llvm::vfs::OnDiskOutputBackend>();
+}
+
+llvm::vfs::OutputBackend &CompilerInstance::getOutputBackend() {
+  assert(TheOutputBackend);
+  return *TheOutputBackend;
+}
+
+llvm::vfs::OutputBackend &CompilerInstance::getOrCreateOutputBackend() {
+  if (!hasOutputBackend())
+    createOutputBackend();
+  return getOutputBackend();
+}
+
+
 std::unique_ptr<raw_pwrite_stream>
 CompilerInstance::createOutputFile(StringRef OutputPath, bool Binary,
                                    bool RemoveFileOnSignal, bool UseTemporary,
                                    bool CreateMissingDirectories) {
   Expected<std::unique_ptr<raw_pwrite_stream>> OS =
       createOutputFileImpl(OutputPath, Binary, RemoveFileOnSignal, UseTemporary,
                            CreateMissingDirectories);
   if (OS)
     return std::move(*OS);
   getDiagnostics().Report(diag::err_fe_unable_to_open_output)
       << OutputPath << errorToErrorCode(OS.takeError()).message();
   return nullptr;
 }
 
 Expected<std::unique_ptr<llvm::raw_pwrite_stream>>
 CompilerInstance::createOutputFileImpl(StringRef OutputPath, bool Binary,
                                        bool RemoveFileOnSignal,
                                        bool UseTemporary,
                                        bool CreateMissingDirectories) {
   assert((!CreateMissingDirectories || UseTemporary) &&
          "CreateMissingDirectories is only allowed when using temporary files");
 
-  std::unique_ptr<llvm::raw_fd_ostream> OS;
-  Optional<StringRef> OSFile;
-
-  if (UseTemporary) {
-    if (OutputPath == "-")
-      UseTemporary = false;
-    else {
-      llvm::sys::fs::file_status Status;
-      llvm::sys::fs::status(OutputPath, Status);
-      if (llvm::sys::fs::exists(Status)) {
-        // Fail early if we can't write to the final destination.
-        if (!llvm::sys::fs::can_write(OutputPath))
-          return llvm::errorCodeToError(
-              make_error_code(llvm::errc::operation_not_permitted));
-
-        // Don't use a temporary if the output is a special file. This handles
-        // things like '-o /dev/null'
-        if (!llvm::sys::fs::is_regular_file(Status))
-          UseTemporary = false;
-      }
-    }
-  }
-
-  Optional<llvm::sys::fs::TempFile> Temp;
-  if (UseTemporary) {
-    // Create a temporary file.
-    // Insert -%%%%%%%% before the extension (if any), and because some tools
-    // (noticeable, clang's own GlobalModuleIndex.cpp) glob for build
-    // artifacts, also append .tmp.
-    StringRef OutputExtension = llvm::sys::path::extension(OutputPath);
-    SmallString<128> TempPath =
-        StringRef(OutputPath).drop_back(OutputExtension.size());
-    TempPath += "-%%%%%%%%";
-    TempPath += OutputExtension;
-    TempPath += ".tmp";
-    Expected<llvm::sys::fs::TempFile> ExpectedFile =
-        llvm::sys::fs::TempFile::create(
-            TempPath, llvm::sys::fs::all_read | llvm::sys::fs::all_write,
-            Binary ? llvm::sys::fs::OF_None : llvm::sys::fs::OF_Text);
-
-    llvm::Error E = handleErrors(
-        ExpectedFile.takeError(), [&](const llvm::ECError &E) -> llvm::Error {
-          std::error_code EC = E.convertToErrorCode();
-          if (CreateMissingDirectories &&
-              EC == llvm::errc::no_such_file_or_directory) {
-            StringRef Parent = llvm::sys::path::parent_path(OutputPath);
-            EC = llvm::sys::fs::create_directories(Parent);
-            if (!EC) {
-              ExpectedFile = llvm::sys::fs::TempFile::create(TempPath);
-              if (!ExpectedFile)
-                return llvm::errorCodeToError(
-                    llvm::errc::no_such_file_or_directory);
-            }
-          }
-          return llvm::errorCodeToError(EC);
-        });
-
-    if (E) {
-      consumeError(std::move(E));
-    } else {
-      Temp = std::move(ExpectedFile.get());
-      OS.reset(new llvm::raw_fd_ostream(Temp->FD, /*shouldClose=*/false));
-      OSFile = Temp->TmpName;
-    }
-    // If we failed to create the temporary, fallback to writing to the file
-    // directly. This handles the corner case where we cannot write to the
-    // directory, but can write to the file.
-  }
-
-  if (!OS) {
-    OSFile = OutputPath;
-    std::error_code EC;
-    OS.reset(new llvm::raw_fd_ostream(
-        *OSFile, EC,
-        (Binary ? llvm::sys::fs::OF_None : llvm::sys::fs::OF_TextWithCRLF)));
-    if (EC)
-      return llvm::errorCodeToError(EC);
-  }
-
-  // Add the output file -- but don't try to remove "-", since this means we are
-  // using stdin.
-  OutputFiles.emplace_back(((OutputPath != "-") ? OutputPath : "").str(),
-                           std::move(Temp));
-
-  if (!Binary || OS->supportsSeeking())
-    return std::move(OS);
-
-  return std::make_unique<llvm::buffer_unique_ostream>(std::move(OS));
+  // If '-working-directory' was passed, the output filename should be
+  // relative to that.
+  Optional<SmallString<128>> AbsPath;
+  if (OutputPath != "-" && !llvm::sys::path::is_absolute(OutputPath)) {
+    AbsPath.emplace(OutputPath);
+    FileMgr->FixupRelativePath(*AbsPath);
+    OutputPath = *AbsPath;
+  }
+
+  using namespace llvm::vfs;
+  Expected<OutputFile> O = getOrCreateOutputBackend().createFile(
+      OutputPath,
+      OutputConfig()
+          .setTextWithCRLF(!Binary)
+          .setDiscardOnSignal(RemoveFileOnSignal)
+          .setAtomicWrite(UseTemporary)
+          .setImplyCreateDirectories(UseTemporary && CreateMissingDirectories));
+  if (!O)
+    return O.takeError();
+
+  O->discardOnDestroy([](llvm::Error E) { consumeError(std::move(E)); });
+  OutputFiles.push_back(std::move(*O));
+  return OutputFiles.back().createProxy();
 }
 
 // Initialization Utilities
 
 bool CompilerInstance::InitializeSourceManager(const FrontendInputFile &Input){
   return InitializeSourceManager(Input, getDiagnostics(), getFileManager(),
                                  getSourceManager());
 }
compileModuleImpl(CompilerInstance &ImportingInstance, SourceLocation ImportLoc,
 
   // Note that this module is part of the module build stack, so that we
   // can detect cycles in the module graph.
   SourceMgr.setModuleBuildStack(
     ImportingInstance.getSourceManager().getModuleBuildStack());
   SourceMgr.pushModuleBuildStack(ModuleName,
     FullSourceLoc(ImportLoc, ImportingInstance.getSourceManager()));
 
+  // Share an output manager.
+  assert(ImportingInstance.hasOutputBackend() &&
+         "Expected an output manager to already be set up");
+  Instance.setOutputBackend(&ImportingInstance.getOutputBackend());
+
   // If we're collecting module dependencies, we need to share a collector
   // between all of the module CompilerInstances. Other than that, we don't
   // want to produce any dependency output from the module build.
   Instance.setModuleDepCollector(ImportingInstance.getModuleDepCollector());
   Inv.getDependencyOutputOpts() = DependencyOutputOptions();
 
   ImportingInstance.getDiagnostics().Report(ImportLoc,
                                             diag::remark_module_build)