1 files changed, 597 insertions, 0 deletions
diff --git a/lib/Remarks/BitstreamRemarkParser.cpp b/lib/Remarks/BitstreamRemarkParser.cpp
new file mode 100644
index 000000000000..99a82e1ee3af
--- /dev/null
+++ b/lib/Remarks/BitstreamRemarkParser.cpp
@@ -0,0 +1,597 @@
+//===- BitstreamRemarkParser.cpp ------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file provides utility methods used by clients that want to use the
+// parser for remark diagnostics in LLVM.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Remarks/BitstreamRemarkParser.h"
+#include "BitstreamRemarkParser.h"
+#include "llvm/Remarks/BitstreamRemarkContainer.h"
+#include "llvm/Support/MemoryBuffer.h"
+#include "llvm/Support/Path.h"
+
+using namespace llvm;
+using namespace llvm::remarks;
+
+static Error unknownRecord(const char *BlockName, unsigned RecordID) {
+  return createStringError(
+      std::make_error_code(std::errc::illegal_byte_sequence),
+      "Error while parsing %s: unknown record entry (%lu).", BlockName,
+      RecordID);
+}
+
+static Error malformedRecord(const char *BlockName, const char *RecordName) {
+  return createStringError(
+      std::make_error_code(std::errc::illegal_byte_sequence),
+      "Error while parsing %s: malformed record entry (%s).", BlockName,
+      RecordName);
+}
+
+BitstreamMetaParserHelper::BitstreamMetaParserHelper(
+    BitstreamCursor &Stream, BitstreamBlockInfo &BlockInfo)
+    : Stream(Stream), BlockInfo(BlockInfo) {}
+
+/// Parse a record and fill in the fields in the parser.
+static Error parseRecord(BitstreamMetaParserHelper &Parser, unsigned Code) {
+  BitstreamCursor &Stream = Parser.Stream;
+  // Note: 2 is used here because it's the max number of fields we have per
+  // record.
+  SmallVector<uint64_t, 2> Record;
+  StringRef Blob;
+  Expected<unsigned> RecordID = Stream.readRecord(Code, Record, &Blob);
+  if (!RecordID)
+    return RecordID.takeError();
+
+  switch (*RecordID) {
+  case RECORD_META_CONTAINER_INFO: {
+    if (Record.size() != 2)
+      return malformedRecord("BLOCK_META", "RECORD_META_CONTAINER_INFO");
+    Parser.ContainerVersion = Record[0];
+    Parser.ContainerType = Record[1];
+    break;
+  }
+  case RECORD_META_REMARK_VERSION: {
+    if (Record.size() != 1)
+      return malformedRecord("BLOCK_META", "RECORD_META_REMARK_VERSION");
+    Parser.RemarkVersion = Record[0];
+    break;
+  }
+  case RECORD_META_STRTAB: {
+    if (Record.size() != 0)
+      return malformedRecord("BLOCK_META", "RECORD_META_STRTAB");
+    Parser.StrTabBuf = Blob;
+    break;
+  }
+  case RECORD_META_EXTERNAL_FILE: {
+    if (Record.size() != 0)
+      return malformedRecord("BLOCK_META", "RECORD_META_EXTERNAL_FILE");
+    Parser.ExternalFilePath = Blob;
+    break;
+  }
+  default:
+    return unknownRecord("BLOCK_META", *RecordID);
+  }
+  return Error::success();
+}
+
+BitstreamRemarkParserHelper::BitstreamRemarkParserHelper(
+    BitstreamCursor &Stream)
+    : Stream(Stream) {}
+
+/// Parse a record and fill in the fields in the parser.
+static Error parseRecord(BitstreamRemarkParserHelper &Parser, unsigned Code) {
+  BitstreamCursor &Stream = Parser.Stream;
+  // Note: 5 is used here because it's the max number of fields we have per
+  // record.
+  SmallVector<uint64_t, 5> Record;
+  StringRef Blob;
+  Expected<unsigned> RecordID = Stream.readRecord(Code, Record, &Blob);
+  if (!RecordID)
+    return RecordID.takeError();
+
+  switch (*RecordID) {
+  case RECORD_REMARK_HEADER: {
+    if (Record.size() != 4)
+      return malformedRecord("BLOCK_REMARK", "RECORD_REMARK_HEADER");
+    Parser.Type = Record[0];
+    Parser.RemarkNameIdx = Record[1];
+    Parser.PassNameIdx = Record[2];
+    Parser.FunctionNameIdx = Record[3];
+    break;
+  }
+  case RECORD_REMARK_DEBUG_LOC: {
+    if (Record.size() != 3)
+      return malformedRecord("BLOCK_REMARK", "RECORD_REMARK_DEBUG_LOC");
+    Parser.SourceFileNameIdx = Record[0];
+    Parser.SourceLine = Record[1];
+    Parser.SourceColumn = Record[2];
+    break;
+  }
+  case RECORD_REMARK_HOTNESS: {
+    if (Record.size() != 1)
+      return malformedRecord("BLOCK_REMARK", "RECORD_REMARK_HOTNESS");
+    Parser.Hotness = Record[0];
+    break;
+  }
+  case RECORD_REMARK_ARG_WITH_DEBUGLOC: {
+    if (Record.size() != 5)
+      return malformedRecord("BLOCK_REMARK", "RECORD_REMARK_ARG_WITH_DEBUGLOC");
+    // Create a temporary argument. Use that as a valid memory location for this
+    // argument entry.
+    Parser.TmpArgs.emplace_back();
+    Parser.TmpArgs.back().KeyIdx = Record[0];
+    Parser.TmpArgs.back().ValueIdx = Record[1];
+    Parser.TmpArgs.back().SourceFileNameIdx = Record[2];
+    Parser.TmpArgs.back().SourceLine = Record[3];
+    Parser.TmpArgs.back().SourceColumn = Record[4];
+    Parser.Args =
+        ArrayRef<BitstreamRemarkParserHelper::Argument>(Parser.TmpArgs);
+    break;
+  }
+  case RECORD_REMARK_ARG_WITHOUT_DEBUGLOC: {
+    if (Record.size() != 2)
+      return malformedRecord("BLOCK_REMARK",
+                             "RECORD_REMARK_ARG_WITHOUT_DEBUGLOC");
+    // Create a temporary argument. Use that as a valid memory location for this
+    // argument entry.
+    Parser.TmpArgs.emplace_back();
+    Parser.TmpArgs.back().KeyIdx = Record[0];
+    Parser.TmpArgs.back().ValueIdx = Record[1];
+    Parser.Args =
+        ArrayRef<BitstreamRemarkParserHelper::Argument>(Parser.TmpArgs);
+    break;
+  }
+  default:
+    return unknownRecord("BLOCK_REMARK", *RecordID);
+  }
+  return Error::success();
+}
+
+template <typename T>
+static Error parseBlock(T &ParserHelper, unsigned BlockID,
+                        const char *BlockName) {
+  BitstreamCursor &Stream = ParserHelper.Stream;
+  Expected<BitstreamEntry> Next = Stream.advance();
+  if (!Next)
+    return Next.takeError();
+  if (Next->Kind != BitstreamEntry::SubBlock || Next->ID != BlockID)
+    return createStringError(
+        std::make_error_code(std::errc::illegal_byte_sequence),
+        "Error while parsing %s: expecting [ENTER_SUBBLOCK, %s, ...].",
+        BlockName, BlockName);
+  if (Stream.EnterSubBlock(BlockID))
+    return createStringError(
+        std::make_error_code(std::errc::illegal_byte_sequence),
+        "Error while entering %s.", BlockName);
+
+  // Stop when there is nothing to read anymore or when we encounter an
+  // END_BLOCK.
+  while (!Stream.AtEndOfStream()) {
+    Expected<BitstreamEntry> Next = Stream.advance();
+    if (!Next)
+      return Next.takeError();
+    switch (Next->Kind) {
+    case BitstreamEntry::EndBlock:
+      return Error::success();
+    case BitstreamEntry::Error:
+    case BitstreamEntry::SubBlock:
+      return createStringError(
+          std::make_error_code(std::errc::illegal_byte_sequence),
+          "Error while parsing %s: expecting records.", BlockName);
+    case BitstreamEntry::Record:
+      if (Error E = parseRecord(ParserHelper, Next->ID))
+        return E;
+      continue;
+    }
+  }
+  // If we're here, it means we didn't get an END_BLOCK yet, but we're at the
+  // end of the stream. In this case, error.
+  return createStringError(
+      std::make_error_code(std::errc::illegal_byte_sequence),
+      "Error while parsing %s: unterminated block.", BlockName);
+}
+
+Error BitstreamMetaParserHelper::parse() {
+  return parseBlock(*this, META_BLOCK_ID, "META_BLOCK");
+}
+
+Error BitstreamRemarkParserHelper::parse() {
+  return parseBlock(*this, REMARK_BLOCK_ID, "REMARK_BLOCK");
+}
+
+BitstreamParserHelper::BitstreamParserHelper(StringRef Buffer)
+    : Stream(Buffer) {}
+
+Expected<std::array<char, 4>> BitstreamParserHelper::parseMagic() {
+  std::array<char, 4> Result;
+  for (unsigned i = 0; i < 4; ++i)
+    if (Expected<unsigned> R = Stream.Read(8))
+      Result[i] = *R;
+    else
+      return R.takeError();
+  return Result;
+}
+
+Error BitstreamParserHelper::parseBlockInfoBlock() {
+  Expected<BitstreamEntry> Next = Stream.advance();
+  if (!Next)
+    return Next.takeError();
+  if (Next->Kind != BitstreamEntry::SubBlock ||
+      Next->ID != llvm::bitc::BLOCKINFO_BLOCK_ID)
+    return createStringError(
+        std::make_error_code(std::errc::illegal_byte_sequence),
+        "Error while parsing BLOCKINFO_BLOCK: expecting [ENTER_SUBBLOCK, "
+        "BLOCKINFO_BLOCK, ...].");
+
+  Expected<Optional<BitstreamBlockInfo>> MaybeBlockInfo =
+      Stream.ReadBlockInfoBlock();
+  if (!MaybeBlockInfo)
+    return MaybeBlockInfo.takeError();
+
+  if (!*MaybeBlockInfo)
+    return createStringError(
+        std::make_error_code(std::errc::illegal_byte_sequence),
+        "Error while parsing BLOCKINFO_BLOCK.");
+
+  BlockInfo = **MaybeBlockInfo;
+
+  Stream.setBlockInfo(&BlockInfo);
+  return Error::success();
+}
+
+static Expected<bool> isBlock(BitstreamCursor &Stream, unsigned BlockID) {
+  bool Result = false;
+  uint64_t PreviousBitNo = Stream.GetCurrentBitNo();
+  Expected<BitstreamEntry> Next = Stream.advance();
+  if (!Next)
+    return Next.takeError();
+  switch (Next->Kind) {
+  case BitstreamEntry::SubBlock:
+    // Check for the block id.
+    Result = Next->ID == BlockID;
+    break;
+  case BitstreamEntry::Error:
+    return createStringError(
+        std::make_error_code(std::errc::illegal_byte_sequence),
+        "Unexpected error while parsing bitstream.");
+  default:
+    Result = false;
+    break;
+  }
+  if (Error E = Stream.JumpToBit(PreviousBitNo))
+    return std::move(E);
+  return Result;
+}
+
+Expected<bool> BitstreamParserHelper::isMetaBlock() {
+  return isBlock(Stream, META_BLOCK_ID);
+}
+
+Expected<bool> BitstreamParserHelper::isRemarkBlock() {
+  return isBlock(Stream, META_BLOCK_ID);
+}
+
+static Error validateMagicNumber(StringRef Magic) {
+  if (Magic != remarks::ContainerMagic)
+    return createStringError(std::make_error_code(std::errc::invalid_argument),
+                             "Unknown magic number: expecting %s, got %.4s.",
+                             remarks::ContainerMagic.data(), Magic.data());
+  return Error::success();
+}
+
+static Error advanceToMetaBlock(BitstreamParserHelper &Helper) {
+  Expected<std::array<char, 4>> Magic = Helper.parseMagic();
+  if (!Magic)
+    return Magic.takeError();
+  if (Error E = validateMagicNumber(StringRef(Magic->data(), Magic->size())))
+    return E;
+  if (Error E = Helper.parseBlockInfoBlock())
+    return E;
+  Expected<bool> isMetaBlock = Helper.isMetaBlock();
+  if (!isMetaBlock)
+    return isMetaBlock.takeError();
+  if (!*isMetaBlock)
+    return createStringError(
+        std::make_error_code(std::errc::illegal_byte_sequence),
+        "Expecting META_BLOCK after the BLOCKINFO_BLOCK.");
+  return Error::success();
+}
+
+Expected<std::unique_ptr<BitstreamRemarkParser>>
+remarks::createBitstreamParserFromMeta(
+    StringRef Buf, Optional<ParsedStringTable> StrTab,
+    Optional<StringRef> ExternalFilePrependPath) {
+  BitstreamParserHelper Helper(Buf);
+  Expected<std::array<char, 4>> Magic = Helper.parseMagic();
+  if (!Magic)
+    return Magic.takeError();
+
+  if (Error E = validateMagicNumber(StringRef(Magic->data(), Magic->size())))
+    return std::move(E);
+
+  auto Parser =
+      StrTab ? std::make_unique<BitstreamRemarkParser>(Buf, std::move(*StrTab))
+             : std::make_unique<BitstreamRemarkParser>(Buf);
+
+  if (ExternalFilePrependPath)
+    Parser->ExternalFilePrependPath = *ExternalFilePrependPath;
+
+  return std::move(Parser);
+}
+
+Expected<std::unique_ptr<Remark>> BitstreamRemarkParser::next() {
+  if (ParserHelper.atEndOfStream())
+    return make_error<EndOfFileError>();
+
+  if (!ReadyToParseRemarks) {
+    if (Error E = parseMeta())
+      return std::move(E);
+    ReadyToParseRemarks = true;
+  }
+
+  return parseRemark();
+}
+
+Error BitstreamRemarkParser::parseMeta() {
+  // Advance and to the meta block.
+  if (Error E = advanceToMetaBlock(ParserHelper))
+    return E;
+
+  BitstreamMetaParserHelper MetaHelper(ParserHelper.Stream,
+                                       ParserHelper.BlockInfo);
+  if (Error E = MetaHelper.parse())
+    return E;
+
+  if (Error E = processCommonMeta(MetaHelper))
+    return E;
+
+  switch (ContainerType) {
+  case BitstreamRemarkContainerType::Standalone:
+    return processStandaloneMeta(MetaHelper);
+  case BitstreamRemarkContainerType::SeparateRemarksFile:
+    return processSeparateRemarksFileMeta(MetaHelper);
+  case BitstreamRemarkContainerType::SeparateRemarksMeta:
+    return processSeparateRemarksMetaMeta(MetaHelper);
+  }
+  llvm_unreachable("Unknown BitstreamRemarkContainerType enum");
+}
+
+Error BitstreamRemarkParser::processCommonMeta(
+    BitstreamMetaParserHelper &MetaHelper) {
+  if (Optional<uint64_t> Version = MetaHelper.ContainerVersion)
+    ContainerVersion = *Version;
+  else
+    return createStringError(
+        std::make_error_code(std::errc::illegal_byte_sequence),
+        "Error while parsing BLOCK_META: missing container version.");
+
+  if (Optional<uint8_t> Type = MetaHelper.ContainerType) {
+    // Always >= BitstreamRemarkContainerType::First since it's unsigned.
+    if (*Type > static_cast<uint8_t>(BitstreamRemarkContainerType::Last))
+      return createStringError(
+          std::make_error_code(std::errc::illegal_byte_sequence),
+          "Error while parsing BLOCK_META: invalid container type.");
+
+    ContainerType = static_cast<BitstreamRemarkContainerType>(*Type);
+  } else
+    return createStringError(
+        std::make_error_code(std::errc::illegal_byte_sequence),
+        "Error while parsing BLOCK_META: missing container type.");
+
+  return Error::success();
+}
+
+static Error processStrTab(BitstreamRemarkParser &P,
+                           Optional<StringRef> StrTabBuf) {
+  if (!StrTabBuf)
+    return createStringError(
+        std::make_error_code(std::errc::illegal_byte_sequence),
+        "Error while parsing BLOCK_META: missing string table.");
+  // Parse and assign the string table.
+  P.StrTab.emplace(*StrTabBuf);
+  return Error::success();
+}
+
+static Error processRemarkVersion(BitstreamRemarkParser &P,
+                                  Optional<uint64_t> RemarkVersion) {
+  if (!RemarkVersion)
+    return createStringError(
+        std::make_error_code(std::errc::illegal_byte_sequence),
+        "Error while parsing BLOCK_META: missing remark version.");
+  P.RemarkVersion = *RemarkVersion;
+  return Error::success();
+}
+
+Error BitstreamRemarkParser::processExternalFilePath(
+    Optional<StringRef> ExternalFilePath) {
+  if (!ExternalFilePath)
+    return createStringError(
+        std::make_error_code(std::errc::illegal_byte_sequence),
+        "Error while parsing BLOCK_META: missing external file path.");
+
+  SmallString<80> FullPath(ExternalFilePrependPath);
+  sys::path::append(FullPath, *ExternalFilePath);
+
+  // External file: open the external file, parse it, check if its metadata
+  // matches the one from the separate metadata, then replace the current parser
+  // with the one parsing the remarks.
+  ErrorOr<std::unique_ptr<MemoryBuffer>> BufferOrErr =
+      MemoryBuffer::getFile(FullPath);
+  if (std::error_code EC = BufferOrErr.getError())
+    return createFileError(FullPath, EC);
+  TmpRemarkBuffer = std::move(*BufferOrErr);
+
+  // Create a separate parser used for parsing the separate file.
+  ParserHelper = BitstreamParserHelper(TmpRemarkBuffer->getBuffer());
+  // Advance and check until we can parse the meta block.
+  if (Error E = advanceToMetaBlock(ParserHelper))
+    return E;
+  // Parse the meta from the separate file.
+  // Note: here we overwrite the BlockInfo with the one from the file. This will
+  // be used to parse the rest of the file.
+  BitstreamMetaParserHelper SeparateMetaHelper(ParserHelper.Stream,
+                                               ParserHelper.BlockInfo);
+  if (Error E = SeparateMetaHelper.parse())
+    return E;
+
+  uint64_t PreviousContainerVersion = ContainerVersion;
+  if (Error E = processCommonMeta(SeparateMetaHelper))
+    return E;
+
+  if (ContainerType != BitstreamRemarkContainerType::SeparateRemarksFile)
+    return createStringError(
+        std::make_error_code(std::errc::illegal_byte_sequence),
+        "Error while parsing external file's BLOCK_META: wrong container "
+        "type.");
+
+  if (PreviousContainerVersion != ContainerVersion)
+    return createStringError(
+        std::make_error_code(std::errc::illegal_byte_sequence),
+        "Error while parsing external file's BLOCK_META: mismatching versions: "
+        "original meta: %lu, external file meta: %lu.",
+        PreviousContainerVersion, ContainerVersion);
+
+  // Process the meta from the separate file.
+  return processSeparateRemarksFileMeta(SeparateMetaHelper);
+}
+
+Error BitstreamRemarkParser::processStandaloneMeta(
+    BitstreamMetaParserHelper &Helper) {
+  if (Error E = processStrTab(*this, Helper.StrTabBuf))
+    return E;
+  return processRemarkVersion(*this, Helper.RemarkVersion);
+}
+
+Error BitstreamRemarkParser::processSeparateRemarksFileMeta(
+    BitstreamMetaParserHelper &Helper) {
+  return processRemarkVersion(*this, Helper.RemarkVersion);
+}
+
+Error BitstreamRemarkParser::processSeparateRemarksMetaMeta(
+    BitstreamMetaParserHelper &Helper) {
+  if (Error E = processStrTab(*this, Helper.StrTabBuf))
+    return E;
+  return processExternalFilePath(Helper.ExternalFilePath);
+}
+
+Expected<std::unique_ptr<Remark>> BitstreamRemarkParser::parseRemark() {
+  BitstreamRemarkParserHelper RemarkHelper(ParserHelper.Stream);
+  if (Error E = RemarkHelper.parse())
+    return std::move(E);
+
+  return processRemark(RemarkHelper);
+}
+
+Expected<std::unique_ptr<Remark>>
+BitstreamRemarkParser::processRemark(BitstreamRemarkParserHelper &Helper) {
+  std::unique_ptr<Remark> Result = std::make_unique<Remark>();
+  Remark &R = *Result;
+
+  if (StrTab == None)
+    return createStringError(
+        std::make_error_code(std::errc::invalid_argument),
+        "Error while parsing BLOCK_REMARK: missing string table.");
+
+  if (!Helper.Type)
+    return createStringError(
+        std::make_error_code(std::errc::illegal_byte_sequence),
+        "Error while parsing BLOCK_REMARK: missing remark type.");
+
+  // Always >= Type::First since it's unsigned.
+  if (*Helper.Type > static_cast<uint8_t>(Type::Last))
+    return createStringError(
+        std::make_error_code(std::errc::illegal_byte_sequence),
+        "Error while parsing BLOCK_REMARK: unknown remark type.");
+
+  R.RemarkType = static_cast<Type>(*Helper.Type);
+
+  if (!Helper.RemarkNameIdx)
+    return createStringError(
+        std::make_error_code(std::errc::illegal_byte_sequence),
+        "Error while parsing BLOCK_REMARK: missing remark name.");
+
+  if (Expected<StringRef> RemarkName = (*StrTab)[*Helper.RemarkNameIdx])
+    R.RemarkName = *RemarkName;
+  else
+    return RemarkName.takeError();
+
+  if (!Helper.PassNameIdx)
+    return createStringError(
+        std::make_error_code(std::errc::illegal_byte_sequence),
+        "Error while parsing BLOCK_REMARK: missing remark pass.");
+
+  if (Expected<StringRef> PassName = (*StrTab)[*Helper.PassNameIdx])
+    R.PassName = *PassName;
+  else
+    return PassName.takeError();
+
+  if (!Helper.FunctionNameIdx)
+    return createStringError(
+        std::make_error_code(std::errc::illegal_byte_sequence),
+        "Error while parsing BLOCK_REMARK: missing remark function name.");
+  if (Expected<StringRef> FunctionName = (*StrTab)[*Helper.FunctionNameIdx])
+    R.FunctionName = *FunctionName;
+  else
+    return FunctionName.takeError();
+
+  if (Helper.SourceFileNameIdx && Helper.SourceLine && Helper.SourceColumn) {
+    Expected<StringRef> SourceFileName = (*StrTab)[*Helper.SourceFileNameIdx];
+    if (!SourceFileName)
+      return SourceFileName.takeError();
+    R.Loc.emplace();
+    R.Loc->SourceFilePath = *SourceFileName;
+    R.Loc->SourceLine = *Helper.SourceLine;
+    R.Loc->SourceColumn = *Helper.SourceColumn;
+  }
+
+  if (Helper.Hotness)
+    R.Hotness = *Helper.Hotness;
+
+  if (!Helper.Args)
+    return std::move(Result);
+
+  for (const BitstreamRemarkParserHelper::Argument &Arg : *Helper.Args) {
+    if (!Arg.KeyIdx)
+      return createStringError(
+          std::make_error_code(std::errc::illegal_byte_sequence),
+          "Error while parsing BLOCK_REMARK: missing key in remark argument.");
+    if (!Arg.ValueIdx)
+      return createStringError(
+          std::make_error_code(std::errc::illegal_byte_sequence),
+          "Error while parsing BLOCK_REMARK: missing value in remark "
+          "argument.");
+
+    // We have at least a key and a value, create an entry.
+    R.Args.emplace_back();
+
+    if (Expected<StringRef> Key = (*StrTab)[*Arg.KeyIdx])
+      R.Args.back().Key = *Key;
+    else
+      return Key.takeError();
+
+    if (Expected<StringRef> Value = (*StrTab)[*Arg.ValueIdx])
+      R.Args.back().Val = *Value;
+    else
+      return Value.takeError();
+
+    if (Arg.SourceFileNameIdx && Arg.SourceLine && Arg.SourceColumn) {
+      if (Expected<StringRef> SourceFileName =
+              (*StrTab)[*Arg.SourceFileNameIdx]) {
+        R.Args.back().Loc.emplace();
+        R.Args.back().Loc->SourceFilePath = *SourceFileName;
+        R.Args.back().Loc->SourceLine = *Arg.SourceLine;
+        R.Args.back().Loc->SourceColumn = *Arg.SourceColumn;
+      } else
+        return SourceFileName.takeError();
+    }
+  }
+
+  return std::move(Result);
+}