[PDB] Simplify API for making section map, NFC

Prevents API misuse described in PR44495

Author: rnk

lld/COFF/PDB.cpp

@@ -178,8 +178,6 @@ class PDBLinker {
 
   llvm::SmallString<128> nativePath;
 
-  std::vector<pdb::SecMapEntry> sectionMap;
-
   /// Type index mappings of type server PDBs that we've loaded so far.
   std::map<codeview::GUID, CVIndexMap> typeServerIndexMappings;
 
@@ -1766,8 +1764,7 @@ void PDBLinker::addSections(ArrayRef<OutputSection *> outputSections,
   ArrayRef<object::coff_section> sections = {
       (const object::coff_section *)sectionTable.data(),
       sectionTable.size() / sizeof(object::coff_section)};
-  sectionMap = pdb::DbiStreamBuilder::createSectionMap(sections);
-  dbiBuilder.setSectionMap(sectionMap);
+  dbiBuilder.createSectionMap(sections);
 
   // Add COFF section header stream.
   exitOnErr(

llvm/include/llvm/DebugInfo/PDB/Native/DbiStreamBuilder.h

@@ -57,7 +57,6 @@ class DbiStreamBuilder {
   void setFlags(uint16_t F);
   void setMachineType(PDB_Machine M);
   void setMachineType(COFF::MachineTypes M);
-  void setSectionMap(ArrayRef<SecMapEntry> SecMap);
 
   // Add given bytes as a new stream.
   Error addDbgStream(pdb::DbgHeaderType Type, ArrayRef<uint8_t> Data);
@@ -84,9 +83,8 @@ class DbiStreamBuilder {
     SectionContribs.emplace_back(SC);
   }
 
-  // A helper function to create a Section Map from a COFF section header.
-  static std::vector<SecMapEntry>
-  createSectionMap(ArrayRef<llvm::object::coff_section> SecHdrs);
+  // Populate the Section Map from COFF section headers.
+  void createSectionMap(ArrayRef<llvm::object::coff_section> SecHdrs);
 
 private:
   struct DebugStream {
@@ -133,7 +131,7 @@ class DbiStreamBuilder {
   WritableBinaryStreamRef NamesBuffer;
   MutableBinaryByteStream FileInfoBuffer;
   std::vector<SectionContrib> SectionContribs;
-  ArrayRef<SecMapEntry> SectionMap;
+  std::vector<SecMapEntry> SectionMap;
   std::array<Optional<DebugStream>, (int)DbgHeaderType::Max> DbgStreams;
 };
 }

llvm/lib/DebugInfo/PDB/Native/DbiStreamBuilder.cpp

@@ -58,10 +58,6 @@ void DbiStreamBuilder::setMachineType(COFF::MachineTypes M) {
   MachineType = static_cast<pdb::PDB_Machine>(static_cast<unsigned>(M));
 }
 
-void DbiStreamBuilder::setSectionMap(ArrayRef<SecMapEntry> SecMap) {
-  SectionMap = SecMap;
-}
-
 void DbiStreamBuilder::setGlobalsStreamIndex(uint32_t Index) {
   GlobalsStreamIndex = Index;
 }
@@ -348,19 +344,18 @@ static uint16_t toSecMapFlags(uint32_t Flags) {
   return Ret;
 }
 
-// A utility function to create a Section Map for a given list of COFF sections.
+// Populate the Section Map from COFF section headers.
 //
 // A Section Map seem to be a copy of a COFF section list in other format.
 // I don't know why a PDB file contains both a COFF section header and
 // a Section Map, but it seems it must be present in a PDB.
-std::vector<SecMapEntry> DbiStreamBuilder::createSectionMap(
+void DbiStreamBuilder::createSectionMap(
     ArrayRef<llvm::object::coff_section> SecHdrs) {
-  std::vector<SecMapEntry> Ret;
   int Idx = 0;
 
   auto Add = [&]() -> SecMapEntry & {
-    Ret.emplace_back();
-    auto &Entry = Ret.back();
+    SectionMap.emplace_back();
+    auto &Entry = SectionMap.back();
     memset(&Entry, 0, sizeof(Entry));
 
     Entry.Frame = Idx + 1;
@@ -384,8 +379,6 @@ std::vector<SecMapEntry> DbiStreamBuilder::createSectionMap(
   Entry.Flags = static_cast<uint16_t>(OMFSegDescFlags::AddressIs32Bit) |
                 static_cast<uint16_t>(OMFSegDescFlags::IsAbsoluteAddress);
   Entry.SecByteLength = UINT32_MAX;
-
-  return Ret;
 }
 
 Error DbiStreamBuilder::commit(const msf::MSFLayout &Layout,
@@ -417,7 +410,7 @@ Error DbiStreamBuilder::commit(const msf::MSFLayout &Layout,
     SecMapHeader SMHeader = {Size, Size};
     if (auto EC = Writer.writeObject(SMHeader))
       return EC;
-    if (auto EC = Writer.writeArray(SectionMap))
+    if (auto EC = Writer.writeArray(makeArrayRef(SectionMap)))
       return EC;
   }