[llvm] [SystemZ][z/OS] TXT records in the GOFF reader (PR #74526)

[James Henderson via llvm-commits]

================
@@ -394,6 +406,161 @@ GOFFObjectFile::getSectionPrEsdRecord(uint32_t SectionIndex) const {
   return EsdRecord;
 }
 
+uint32_t GOFFObjectFile::getSectionDefEsdId(DataRefImpl &Sec) const {
+  const uint8_t *EsdRecord = getSectionEdEsdRecord(Sec);
+  uint32_t Length;
+  ESDRecord::getLength(EsdRecord, Length);
+  if (Length == 0) {
+    const uint8_t *PrEsdRecord = getSectionPrEsdRecord(Sec);
+    if (PrEsdRecord)
+      EsdRecord = PrEsdRecord;
+  }
+
+  uint32_t DefEsdId;
+  ESDRecord::getEsdId(EsdRecord, DefEsdId);
+  LLVM_DEBUG(dbgs() << "Got def EsdId: " << DefEsdId << '\n');
+  return DefEsdId;
+}
+
+void GOFFObjectFile::moveSectionNext(DataRefImpl &Sec) const {
+  Sec.d.a++;
+  if ((Sec.d.a) >= SectionList.size())
+    Sec.d.a = 0;
+}
+
+Expected<StringRef> GOFFObjectFile::getSectionName(DataRefImpl Sec) const {
+  DataRefImpl EdSym;
+  SectionEntryImpl EsdIds = SectionList[Sec.d.a];
+  EdSym.d.a = EsdIds.d.a;
+  Expected<StringRef> Name = getSymbolName(EdSym);
+  if (Name) {
+    StringRef Res = *Name;
+    LLVM_DEBUG(dbgs() << "Got section: " << Res << '\n');
+    // TODO: Make clang look for C____clangast instead of this
+    if (Res.equals("C___clangast"))
+      Res = "__clangast";
+    LLVM_DEBUG(dbgs() << "Final section name: " << Res << '\n');
+    Name = Res;
+  }
+  return Name;
+}
+
+uint64_t GOFFObjectFile::getSectionAddress(DataRefImpl Sec) const {
+  uint32_t Offset;
+  const uint8_t *EsdRecord = getSectionEdEsdRecord(Sec);
+  ESDRecord::getOffset(EsdRecord, Offset);
+  return Offset;
+}
+
+uint64_t GOFFObjectFile::getSectionSize(DataRefImpl Sec) const {
+  uint32_t Length;
+  uint32_t DefEsdId = getSectionDefEsdId(Sec);
+  const uint8_t *EsdRecord = EsdPtrs[DefEsdId];
+  ESDRecord::getLength(EsdRecord, Length);
+  LLVM_DEBUG(dbgs() << "Got section size: " << Length << '\n');
+  return static_cast<uint64_t>(Length);
+}
+
+// Unravel TXT records and expand fill characters to produce
+// a contiguous sequence of bytes
+Expected<ArrayRef<uint8_t>>
+GOFFObjectFile::getSectionContents(DataRefImpl Sec) const {
+  if (SectionDataCache.count(Sec.d.a)) {
+    auto &Buf = SectionDataCache[Sec.d.a];
+    return ArrayRef<uint8_t>(Buf.second.get(), Buf.first);
+  }
+
+  uint64_t SectionSize = getSectionSize(Sec);
+  uint32_t DefEsdId = getSectionDefEsdId(Sec);
+
+  const uint8_t *EdEsdRecord = getSectionEdEsdRecord(Sec);
+  bool FillBytePresent;
+  ESDRecord::getFillBytePresent(EdEsdRecord, FillBytePresent);
+  uint8_t FillByte = '\0';
+  if (FillBytePresent)
+    ESDRecord::getFillByteValue(EdEsdRecord, FillByte);
+
+  // Initialize section with fill byte.
+  auto DataPtr =
+      std::make_pair(SectionSize, std::make_unique<uint8_t[]>(SectionSize));
+  uint8_t *Data = DataPtr.second.get();
+  memset(Data, FillByte, SectionSize);
+
+  // Replace section with content from text records.
+  for (const uint8_t *TxtRecordInt : TextPtrs) {
+    const uint8_t *TxtRecordPtr = TxtRecordInt;
+    uint32_t TxtEsdId;
+    TXTRecord::getElementEsdId(TxtRecordPtr, TxtEsdId);
+    LLVM_DEBUG(dbgs() << "Got txt EsdId: " << TxtEsdId << '\n');
+
+    if (TxtEsdId != DefEsdId)
+      continue;
+
+    uint32_t TxtDataOffset;
+    TXTRecord::getOffset(TxtRecordPtr, TxtDataOffset);
+
+    uint16_t TxtDataSize;
+    TXTRecord::getDataLength(TxtRecordPtr, TxtDataSize);
+
+    LLVM_DEBUG(dbgs() << "Record offset " << TxtDataOffset << ", data size "
+                      << TxtDataSize << "\n");
+
+    SmallString<256> CompleteData;
+    CompleteData.reserve(TxtDataSize);
+    if (auto Err = TXTRecord::getData(TxtRecordPtr, CompleteData))
+      return std::move(Err);
+    assert(CompleteData.size() == TxtDataSize && "Wrong length of data");
+    memcpy(Data + TxtDataOffset, CompleteData.data(), TxtDataSize);
+  }
+
+  SectionDataCache[Sec.d.a] = std::move(DataPtr);
+  return ArrayRef<uint8_t>(Data, SectionSize);
+}
+
+uint64_t GOFFObjectFile::getSectionAlignment(DataRefImpl Sec) const {
+  const uint8_t *EsdRecord = getSectionEdEsdRecord(Sec);
+  GOFF::ESDAlignment Pow2Alignment;
+  ESDRecord::getAlignment(EsdRecord, Pow2Alignment);
+  return 1 << (uint64_t)Pow2Alignment;
----------------
jh7370 wrote:

This should probably be a `static_cast` [rather than C-style cast.](https://llvm.org/docs/CodingStandards.html#prefer-c-style-casts)

https://github.com/llvm/llvm-project/pull/74526