InstrProf: Simplify the construction of BinaryCoverageReader

Creating BinaryCoverageReader is a strange and complicated dance where
the constructor sets error codes that member functions will later
read, and the object is in an invalid state if readHeader isn't
immediately called after construction.

Instead, make the constructor private and add a static create method
to do the construction properly. This also has the benefit of removing
readHeader completely and simplifying the interface of the object.

llvm-svn: 230676

1 files changed, 55 insertions, 60 deletions

diff --git a/llvm/lib/ProfileData/CoverageMappingReader.cpp b/llvm/lib/ProfileData/CoverageMappingReader.cpp
index 168115a1534..d32f1dac456 100644
--- a/llvm/lib/ProfileData/CoverageMappingReader.cpp
+++ b/llvm/lib/ProfileData/CoverageMappingReader.cpp
@@ -411,9 +411,12 @@ std::error_code readCoverageMappingData(
 
 static const char *TestingFormatMagic = "llvmcovmtestdata";
 
-static std::error_code decodeTestingFormat(StringRef Data,
-                                           SectionData &ProfileNames,
-                                           StringRef &CoverageMapping) {
+static std::error_code loadTestingFormat(StringRef Data,
+                                         SectionData &ProfileNames,
+                                         StringRef &CoverageMapping,
+                                         uint8_t &BytesInAddress) {
+  BytesInAddress = 8;
+
   Data = Data.substr(StringRef(TestingFormatMagic).size());
   if (Data.size() < 1)
     return instrprof_error::truncated;
@@ -438,86 +441,78 @@ static std::error_code decodeTestingFormat(StringRef Data,
   return instrprof_error::success;
 }
 
-BinaryCoverageReader::BinaryCoverageReader(
-    std::unique_ptr<MemoryBuffer> &ObjectBuffer)
-    : CurrentRecord(0) {
-  if (ObjectBuffer->getBuffer().startswith(TestingFormatMagic)) {
-    // This is a special format used for testing.
-    SectionData ProfileNames;
-    StringRef CoverageMapping;
-    if (auto Err = decodeTestingFormat(ObjectBuffer->getBuffer(), ProfileNames,
-                                       CoverageMapping)) {
-      error(Err);
-      return;
-    }
-    error(readCoverageMappingData<uint64_t>(ProfileNames, CoverageMapping,
-                                            MappingRecords, Filenames));
-    Object = OwningBinary<ObjectFile>(std::unique_ptr<ObjectFile>(),
-                                      std::move(ObjectBuffer));
-    return;
-  }
-
-  auto File =
-      object::ObjectFile::createObjectFile(ObjectBuffer->getMemBufferRef());
-  if (!File)
-    error(File.getError());
-  else
-    Object = OwningBinary<ObjectFile>(std::move(File.get()),
-                                      std::move(ObjectBuffer));
-}
-
-std::error_code BinaryCoverageReader::readHeader() {
-  const ObjectFile *OF = Object.getBinary();
-  if (!OF)
-    return getError();
-  auto BytesInAddress = OF->getBytesInAddress();
-  if (BytesInAddress != 4 && BytesInAddress != 8)
-    return error(instrprof_error::malformed);
+static std::error_code loadBinaryFormat(MemoryBufferRef ObjectBuffer,
+                                        SectionData &ProfileNames,
+                                        StringRef &CoverageMapping,
+                                        uint8_t &BytesInAddress) {
+  auto ObjectFileOrErr = object::ObjectFile::createObjectFile(ObjectBuffer);
+  if (std::error_code EC = ObjectFileOrErr.getError())
+    return EC;
+  auto OF = std::move(ObjectFileOrErr.get());
+  BytesInAddress = OF->getBytesInAddress();
 
   // Look for the sections that we are interested in.
   int FoundSectionCount = 0;
-  SectionRef ProfileNames, CoverageMapping;
+  SectionRef NamesSection, CoverageSection;
   for (const auto &Section : OF->sections()) {
     StringRef Name;
     if (auto Err = Section.getName(Name))
       return Err;
     if (Name == "__llvm_prf_names") {
-      ProfileNames = Section;
+      NamesSection = Section;
     } else if (Name == "__llvm_covmap") {
-      CoverageMapping = Section;
+      CoverageSection = Section;
     } else
       continue;
     ++FoundSectionCount;
   }
   if (FoundSectionCount != 2)
-    return error(instrprof_error::bad_header);
+    return instrprof_error::bad_header;
 
   // Get the contents of the given sections.
-  StringRef Data;
-  if (auto Err = CoverageMapping.getContents(Data))
-    return Err;
-  SectionData ProfileNamesData;
-  if (auto Err = ProfileNamesData.load(ProfileNames))
-    return Err;
+  if (std::error_code EC = CoverageSection.getContents(CoverageMapping))
+    return EC;
+  if (std::error_code EC = ProfileNames.load(NamesSection))
+    return EC;
 
-  // Load the data from the found sections.
-  std::error_code Err;
-  if (BytesInAddress == 4)
-    Err = readCoverageMappingData<uint32_t>(ProfileNamesData, Data,
-                                            MappingRecords, Filenames);
+  return std::error_code();
+}
+
+ErrorOr<std::unique_ptr<BinaryCoverageReader>>
+BinaryCoverageReader::create(std::unique_ptr<MemoryBuffer> &ObjectBuffer) {
+  std::unique_ptr<BinaryCoverageReader> Reader(new BinaryCoverageReader());
+
+  SectionData Profile;
+  StringRef Coverage;
+  uint8_t BytesInAddress;
+  std::error_code EC;
+  if (ObjectBuffer->getBuffer().startswith(TestingFormatMagic))
+    // This is a special format used for testing.
+    EC = loadTestingFormat(ObjectBuffer->getBuffer(), Profile, Coverage,
+                           BytesInAddress);
   else
-    Err = readCoverageMappingData<uint64_t>(ProfileNamesData, Data,
-                                            MappingRecords, Filenames);
-  if (Err)
-    return error(Err);
+    EC = loadBinaryFormat(ObjectBuffer->getMemBufferRef(), Profile, Coverage,
+                          BytesInAddress);
+  if (EC)
+    return EC;
 
-  return success();
+  if (BytesInAddress == 4)
+    EC = readCoverageMappingData<uint32_t>(
+        Profile, Coverage, Reader->MappingRecords, Reader->Filenames);
+  else if (BytesInAddress == 8)
+    EC = readCoverageMappingData<uint64_t>(
+        Profile, Coverage, Reader->MappingRecords, Reader->Filenames);
+  else
+    return instrprof_error::malformed;
+  if (EC)
+    return EC;
+  return std::move(Reader);
 }
 
 std::error_code
 BinaryCoverageReader::readNextRecord(CoverageMappingRecord &Record) {
   if (CurrentRecord >= MappingRecords.size())
-    return error(instrprof_error::eof);
+    return instrprof_error::eof;
 
   FunctionsFilenames.clear();
   Expressions.clear();
@@ -537,5 +532,5 @@ BinaryCoverageReader::readNextRecord(CoverageMappingRecord &Record) {
   Record.MappingRegions = MappingRegions;
 
   ++CurrentRecord;
-  return success();
+  return std::error_code();
 }