Use ErrorOr for the ::create factory on instrumented and sample profilers.

[dnovillo]

Summary

As discussed in
http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20141027/242445.html,
the creation of reader and writer instances is better done using
ErrorOr. There are no functional changes, but several callers needed to
be adjusted.

[dnovillo]

Closed by commit rL221120 (authored by @dnovillo).

include/llvm/ProfileData/InstrProfReader.h

 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_PROFILEDATA_INSTRPROFREADER_H
 #define LLVM_PROFILEDATA_INSTRPROFREADER_H
 
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/ProfileData/InstrProf.h"
+#include "llvm/Support/ErrorOr.h"
 #include "llvm/Support/LineIterator.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/EndianStream.h"
 #include "llvm/Support/OnDiskHashTable.h"
 
 #include <iterator>
 
 namespace llvm {
public:
   bool isEOF() { return LastError == instrprof_error::eof; }
   /// Return true if the reader encountered an error reading profiling data.
   bool hasError() { return LastError && !isEOF(); }
   /// Get the current error code.
   std::error_code getError() { return LastError; }
 
   /// Factory method to create an appropriately typed reader for the given
   /// instrprof file.
-  static std::error_code create(std::string Path,
-                                std::unique_ptr<InstrProfReader> &Result);
+  static ErrorOr<std::unique_ptr<InstrProfReader>> create(std::string Path);
 };
 
 /// Reader for the simple text based instrprof format.
 ///
 /// This format is a simple text format that's suitable for test data. Records
 /// are separated by one or more blank lines, and record fields are separated by
 /// new lines.
 ///

include/llvm/ProfileData/SampleProfReader.h

public:
 
   /// \brief Report a parse error message.
   void reportParseError(int64_t LineNumber, Twine Msg) const {
     Ctx.diagnose(DiagnosticInfoSampleProfile(Buffer->getBufferIdentifier(),
                                              LineNumber, Msg));
   }
 
   /// \brief Create a sample profile reader appropriate to the file format.
-  static std::error_code create(StringRef Filename,
-                                std::unique_ptr<SampleProfileReader> &Reader,
-                                LLVMContext &C);
+  static ErrorOr<std::unique_ptr<SampleProfileReader>>
+  create(StringRef Filename, LLVMContext &C);
 
 protected:
   /// \brief Map every function to its associated profile.
   ///
   /// The profile of every function executed at runtime is collected
   /// in the structure FunctionSamples. This maps function objects
   /// to their corresponding profiles.
   StringMap<FunctionSamples> Profiles;

include/llvm/ProfileData/SampleProfWriter.h

 //===----------------------------------------------------------------------===//
 #ifndef LLVM_PROFILEDATA_SAMPLEPROFWRITER_H
 #define LLVM_PROFILEDATA_SAMPLEPROFWRITER_H
 
 #include "llvm/ADT/StringRef.h"
 #include "llvm/IR/Function.h"
 #include "llvm/IR/Module.h"
 #include "llvm/ProfileData/SampleProf.h"
+#include "llvm/Support/ErrorOr.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/raw_ostream.h"
 
 namespace llvm {
 
 namespace sampleprof {
 
 enum SampleProfileFormat { SPF_None = 0, SPF_Text, SPF_Binary, SPF_GCC };
for (auto &I : ProfileMap) {
       if (!write(FName, Profile))
         return false;
     }
     return true;
   }
 
   /// \brief Profile writer factory. Create a new writer based on the value of
   /// \p Format.
-  static std::error_code create(StringRef Filename,
-                                std::unique_ptr<SampleProfileWriter> &Result,
-                                SampleProfileFormat Format);
+  static ErrorOr<std::unique_ptr<SampleProfileWriter>>
+  create(StringRef Filename, SampleProfileFormat Format);
 
 protected:
   /// \brief Output stream where to emit the profile to.
   raw_fd_ostream OS;
 };
 
 /// \brief Sample-based profile writer (text format).
 class SampleProfileWriterText : public SampleProfileWriter {

lib/ProfileData/InstrProfReader.cpp

 #include "llvm/ProfileData/InstrProf.h"
 
 #include "InstrProfIndexed.h"
 
 #include <cassert>
 
 using namespace llvm;
 
-static std::error_code
-setupMemoryBuffer(std::string Path, std::unique_ptr<MemoryBuffer> &Buffer) {
+static ErrorOr<std::unique_ptr<MemoryBuffer>>
+setupMemoryBuffer(std::string Path) {
   ErrorOr<std::unique_ptr<MemoryBuffer>> BufferOrErr =
       MemoryBuffer::getFileOrSTDIN(Path);
   if (std::error_code EC = BufferOrErr.getError())
     return EC;
-  Buffer = std::move(BufferOrErr.get());
+  auto Buffer = std::move(BufferOrErr.get());
 
   // Sanity check the file.
   if (Buffer->getBufferSize() > std::numeric_limits<unsigned>::max())
     return instrprof_error::too_large;
-  return instrprof_error::success;
+  return std::move(Buffer);
 }
 
 static std::error_code initializeReader(InstrProfReader &Reader) {
   return Reader.readHeader();
 }
 
-std::error_code
-InstrProfReader::create(std::string Path,
-                        std::unique_ptr<InstrProfReader> &Result) {
+ErrorOr<std::unique_ptr<InstrProfReader>>
+InstrProfReader::create(std::string Path) {
   // Set up the buffer to read.
-  std::unique_ptr<MemoryBuffer> Buffer;
-  if (std::error_code EC = setupMemoryBuffer(Path, Buffer))
+  auto BufferOrError = setupMemoryBuffer(Path);
+  if (std::error_code EC = BufferOrError.getError())
     return EC;
 
+  auto Buffer = std::move(BufferOrError.get());
+  std::unique_ptr<InstrProfReader> Result;
+
   // Create the reader.
   if (IndexedInstrProfReader::hasFormat(*Buffer))
     Result.reset(new IndexedInstrProfReader(std::move(Buffer)));
   else if (RawInstrProfReader64::hasFormat(*Buffer))
     Result.reset(new RawInstrProfReader64(std::move(Buffer)));
   else if (RawInstrProfReader32::hasFormat(*Buffer))
     Result.reset(new RawInstrProfReader32(std::move(Buffer)));
   else
     Result.reset(new TextInstrProfReader(std::move(Buffer)));
 
   // Initialize the reader and return the result.
-  return initializeReader(*Result);
+  if (std::error_code EC = initializeReader(*Result))
+    return EC;
+
+  return std::move(Result);
 }
 
 std::error_code IndexedInstrProfReader::create(
     std::string Path, std::unique_ptr<IndexedInstrProfReader> &Result) {
   // Set up the buffer to read.
-  std::unique_ptr<MemoryBuffer> Buffer;
-  if (std::error_code EC = setupMemoryBuffer(Path, Buffer))
+  auto BufferOrError = setupMemoryBuffer(Path);
+  if (std::error_code EC = BufferOrError.getError())
     return EC;
 
+  auto Buffer = std::move(BufferOrError.get());
   // Create the reader.
   if (!IndexedInstrProfReader::hasFormat(*Buffer))
     return instrprof_error::bad_magic;
   Result.reset(new IndexedInstrProfReader(std::move(Buffer)));
 
   // Initialize the reader and return the result.
   return initializeReader(*Result);
 }

lib/ProfileData/SampleProfReader.cpp

const uint8_t *Data =
       reinterpret_cast<const uint8_t *>(Buffer.getBufferStart());
   uint64_t Magic = decodeULEB128(Data);
   return Magic == SPMagic();
 }
 
 /// \brief Prepare a memory buffer for the contents of \p Filename.
 ///
 /// \returns an error code indicating the status of the buffer.
-static std::error_code
-setupMemoryBuffer(std::string Filename, std::unique_ptr<MemoryBuffer> &Buffer) {
+static ErrorOr<std::unique_ptr<MemoryBuffer>>
+setupMemoryBuffer(std::string Filename) {
   auto BufferOrErr = MemoryBuffer::getFileOrSTDIN(Filename);
   if (std::error_code EC = BufferOrErr.getError())
     return EC;
-  Buffer = std::move(BufferOrErr.get());
+  auto Buffer = std::move(BufferOrErr.get());
 
   // Sanity check the file.
   if (Buffer->getBufferSize() > std::numeric_limits<unsigned>::max())
     return sampleprof_error::too_large;
 
-  return sampleprof_error::success;
+  return std::move(Buffer);
 }
 
 /// \brief Create a sample profile reader based on the format of the input file.
 ///
 /// \param Filename The file to open.
 ///
 /// \param Reader The reader to instantiate according to \p Filename's format.
 ///
 /// \param C The LLVM context to use to emit diagnostics.
 ///
 /// \returns an error code indicating the status of the created reader.
-std::error_code
-SampleProfileReader::create(StringRef Filename,
-                            std::unique_ptr<SampleProfileReader> &Reader,
-                            LLVMContext &C) {
-  std::unique_ptr<MemoryBuffer> Buffer;
-  if (std::error_code EC = setupMemoryBuffer(Filename, Buffer))
+ErrorOr<std::unique_ptr<SampleProfileReader>>
+SampleProfileReader::create(StringRef Filename, LLVMContext &C) {
+  auto BufferOrError = setupMemoryBuffer(Filename);
+  if (std::error_code EC = BufferOrError.getError())
     return EC;
 
+  auto Buffer = std::move(BufferOrError.get());
+  std::unique_ptr<SampleProfileReader> Reader;
   if (SampleProfileReaderBinary::hasFormat(*Buffer))
     Reader.reset(new SampleProfileReaderBinary(std::move(Buffer), C));
   else
     Reader.reset(new SampleProfileReaderText(std::move(Buffer), C));
 
-  return Reader->readHeader();
+  if (std::error_code EC = Reader->readHeader())
+    return EC;
+
+  return std::move(Reader);
 }

lib/ProfileData/SampleProfWriter.cpp

 ///
 /// \param Filename The file to create.
 ///
 /// \param Writer The writer to instantiate according to the specified format.
 ///
 /// \param Format Encoding format for the profile file.
 ///
 /// \returns an error code indicating the status of the created writer.
-std::error_code
-SampleProfileWriter::create(StringRef Filename,
-                            std::unique_ptr<SampleProfileWriter> &Writer,
-                            SampleProfileFormat Format) {
+ErrorOr<std::unique_ptr<SampleProfileWriter>>
+SampleProfileWriter::create(StringRef Filename, SampleProfileFormat Format) {
   std::error_code EC;
+  std::unique_ptr<SampleProfileWriter> Writer;
 
   if (Format == SPF_Binary)
     Writer.reset(new SampleProfileWriterBinary(Filename, EC));
   else if (Format == SPF_Text)
     Writer.reset(new SampleProfileWriterText(Filename, EC));
   else
     EC = sampleprof_error::unrecognized_format;
 
+  if (EC)
     return EC;
+
+  return std::move(Writer);
 }

lib/Transforms/Scalar/SampleProfile.cpp

 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
 INITIALIZE_PASS_DEPENDENCY(PostDominatorTree)
 INITIALIZE_PASS_DEPENDENCY(LoopInfo)
 INITIALIZE_PASS_DEPENDENCY(AddDiscriminators)
 INITIALIZE_PASS_END(SampleProfileLoader, "sample-profile",
                     "Sample Profile loader", false, false)
 
 bool SampleProfileLoader::doInitialization(Module &M) {
-  if (std::error_code EC =
-          SampleProfileReader::create(Filename, Reader, M.getContext())) {
+  auto ReaderOrErr = SampleProfileReader::create(Filename, M.getContext());
+  if (std::error_code EC = ReaderOrErr.getError()) {
     std::string Msg = "Could not open profile: " + EC.message();
     M.getContext().diagnose(DiagnosticInfoSampleProfile(Filename.data(), Msg));
     return false;
   }
+  Reader = std::move(ReaderOrErr.get());
   ProfileIsValid = (Reader->read() == sampleprof_error::success);
   return true;
 }
 
 FunctionPass *llvm::createSampleProfileLoaderPass() {
   return new SampleProfileLoader(SampleProfileFile);
 }
 

tools/llvm-profdata/llvm-profdata.cpp

void mergeInstrProfile(cl::list<std::string> Inputs, StringRef OutputFilename) {
 
   std::error_code EC;
   raw_fd_ostream Output(OutputFilename.data(), EC, sys::fs::F_None);
   if (EC)
     exitWithError(EC.message(), OutputFilename);
 
   InstrProfWriter Writer;
   for (const auto &Filename : Inputs) {
-    std::unique_ptr<InstrProfReader> Reader;
-    if (std::error_code ec = InstrProfReader::create(Filename, Reader))
+    auto ReaderOrErr = InstrProfReader::create(Filename);
+    if (std::error_code ec = ReaderOrErr.getError())
       exitWithError(ec.message(), Filename);
 
+    auto Reader = std::move(ReaderOrErr.get());
     for (const auto &I : *Reader)
       if (std::error_code EC =
               Writer.addFunctionCounts(I.Name, I.Hash, I.Counts))
         errs() << Filename << ": " << I.Name << ": " << EC.message() << "\n";
     if (Reader->hasError())
       exitWithError(Reader->getError().message(), Filename);
   }
   Writer.write(Output);
 }
 
 void mergeSampleProfile(cl::list<std::string> Inputs, StringRef OutputFilename,
                         sampleprof::SampleProfileFormat OutputFormat) {
   using namespace sampleprof;
-  std::unique_ptr<SampleProfileWriter> Writer;
-  if (std::error_code EC = SampleProfileWriter::create(OutputFilename.data(),
-                                                       Writer, OutputFormat))
+  auto WriterOrErr = SampleProfileWriter::create(OutputFilename, OutputFormat);
+  if (std::error_code EC = WriterOrErr.getError())
     exitWithError(EC.message(), OutputFilename);
 
+  auto Writer = std::move(WriterOrErr.get());
   StringMap<FunctionSamples> ProfileMap;
   for (const auto &Filename : Inputs) {
-    std::unique_ptr<SampleProfileReader> Reader;
-    if (std::error_code EC =
-            SampleProfileReader::create(Filename, Reader, getGlobalContext()))
+    auto ReaderOrErr =
+        SampleProfileReader::create(Filename, getGlobalContext());
+    if (std::error_code EC = ReaderOrErr.getError())
       exitWithError(EC.message(), Filename);
 
+    auto Reader = std::move(ReaderOrErr.get());
     if (std::error_code EC = Reader->read())
       exitWithError(EC.message(), Filename);
 
     StringMap<FunctionSamples> &Profiles = Reader->getProfiles();
     for (StringMap<FunctionSamples>::iterator I = Profiles.begin(),
                                               E = Profiles.end();
          I != E; ++I) {
       StringRef FName = I->first();
else
     mergeSampleProfile(Inputs, OutputFilename, OutputFormat);
 
   return 0;
 }
 
 int showInstrProfile(std::string Filename, bool ShowCounts,
                      bool ShowAllFunctions, std::string ShowFunction,
                      raw_fd_ostream &OS) {
-  std::unique_ptr<InstrProfReader> Reader;
-  if (std::error_code EC = InstrProfReader::create(Filename, Reader))
+  auto ReaderOrErr = InstrProfReader::create(Filename);
+  if (std::error_code EC = ReaderOrErr.getError())
     exitWithError(EC.message(), Filename);
 
+  auto Reader = std::move(ReaderOrErr.get());
   uint64_t MaxFunctionCount = 0, MaxBlockCount = 0;
   size_t ShownFunctions = 0, TotalFunctions = 0;
   for (const auto &Func : *Reader) {
     bool Show =
         ShowAllFunctions || (!ShowFunction.empty() &&
                              Func.Name.find(ShowFunction) != Func.Name.npos);
 
     ++TotalFunctions;
int showInstrProfile(std::string Filename, bool ShowCounts,
   OS << "Maximum internal block count: " << MaxBlockCount << "\n";
   return 0;
 }
 
 int showSampleProfile(std::string Filename, bool ShowCounts,
                       bool ShowAllFunctions, std::string ShowFunction,
                       raw_fd_ostream &OS) {
   using namespace sampleprof;
-  std::unique_ptr<SampleProfileReader> Reader;
-  if (std::error_code EC =
-          SampleProfileReader::create(Filename, Reader, getGlobalContext()))
+  auto ReaderOrErr = SampleProfileReader::create(Filename, getGlobalContext());
+  if (std::error_code EC = ReaderOrErr.getError())
     exitWithError(EC.message(), Filename);
 
+  auto Reader = std::move(ReaderOrErr.get());
   Reader->read();
   if (ShowAllFunctions || ShowFunction.empty())
     Reader->dump(OS);
   else
     Reader->dumpFunctionProfile(ShowFunction, OS);
 
   return 0;
 }