[llvm] [SystemZ][z/OS] Implement yaml2obj for GOFF Object File Format (PR #71445)

[James Henderson via llvm-commits]

================
@@ -0,0 +1,451 @@
+//===- yaml2goff - Convert YAML to a GOFF object file ---------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// The GOFF component of yaml2obj.
+///
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ADT/IndexedMap.h"
+#include "llvm/ObjectYAML/ObjectYAML.h"
+#include "llvm/ObjectYAML/yaml2obj.h"
+#include "llvm/Support/ConvertEBCDIC.h"
+#include "llvm/Support/Endian.h"
+#include "llvm/Support/raw_ostream.h"
+
+using namespace llvm;
+
+namespace {
+
+static const uint8_t TXTMaxDataLength = 56;
+
+// Common flag values on records.
+enum {
+  // Flag: This record is continued.
+  Rec_Continued = 1 << (8 - 7 - 1),
+
+  // Flag: This record is a continuation.
+  Rec_Continuation = 1 << (8 - 6 - 1),
+};
+
+template <typename value_type> struct BinaryBeImpl {
+  value_type Value;
+  BinaryBeImpl(value_type V) : Value(V) {}
+};
+
+template <typename value_type>
+raw_ostream &operator<<(raw_ostream &OS, const BinaryBeImpl<value_type> &BBE) {
+  char Buffer[sizeof(BBE.Value)];
+  support::endian::write<value_type, llvm::endianness::big, support::unaligned>(
+      Buffer, BBE.Value);
+  OS.write(Buffer, sizeof(BBE.Value));
+  return OS;
+}
+
+template <typename value_type> BinaryBeImpl<value_type> binaryBe(value_type V) {
+  return BinaryBeImpl<value_type>(V);
+}
+
+struct ZerosImpl {
+  size_t NumBytes;
+};
+
+raw_ostream &operator<<(raw_ostream &OS, const ZerosImpl &Z) {
+  OS.write_zeros(Z.NumBytes);
+  return OS;
+}
+
+ZerosImpl zeros(const size_t NumBytes) { return ZerosImpl{NumBytes}; }
+
+raw_ostream &operator<<(raw_ostream &OS, const yaml::BinaryRef &Data) {
+  Data.writeAsBinary(OS);
+  return OS;
+}
+
+// The GOFFOstream is responsible to write the data into the fixed physical
+// records of the format. A user of this class announces the the begin of a new
+// logical record and the size of its payload. While writing the payload, the
+// physical records are created for the data. Possible fill bytes at the end of
+// a physical record are written automatically.
+class GOFFOstream : public raw_ostream {
+  /// The underlying raw_ostream.
+  raw_ostream &OS;
+
+  /// The number of logical records emitted to far.
+  uint32_t LogicalRecords;
+
+  /// The remaining size of this logical record, including fill
+  /// bytes.
+  size_t RemainingSize;
+
+  /// The type of the current (logical) record.
+  GOFF::RecordType CurrentType;
+
+  /// Signals begin of new record.
+  bool NewLogicalRecord;
+
+  // Return the number of bytes left to write until next physical record.
+  // Please note that we maintain the total numbers of byte left, not the
+  // written size.
+  size_t bytesToNextPhysicalRecord() {
+    size_t Bytes = RemainingSize % GOFF::PayloadLength;
+    return Bytes ? Bytes : GOFF::PayloadLength;
+  }
+
+  /// Write the record prefix of a physical record, using the current record
+  /// type.
+  static void writeRecordPrefix(raw_ostream &OS, GOFF::RecordType Type,
+                                size_t RemainingSize,
+                                uint8_t Flags = Rec_Continuation);
+
+  /// Fill the last physical record of a logical record with zero bytes.
+  void fillRecord();
+
+  /// See raw_ostream::write_impl.
+  void write_impl(const char *Ptr, size_t Size) override;
+
+  /// Return the current position within the stream, not counting the bytes
+  /// currently in the buffer.
+  uint64_t current_pos() const override { return OS.tell(); }
+
+public:
+  explicit GOFFOstream(raw_ostream &OS)
+      : OS(OS), LogicalRecords(0), RemainingSize(0), NewLogicalRecord(false) {
+    SetBufferSize(GOFF::PayloadLength);
+  }
+
+  ~GOFFOstream() { finalize(); }
+
+  void newRecord(GOFF::RecordType Type, size_t Size);
+
+  void finalize() { fillRecord(); }
+
+  uint32_t logicalRecords() { return LogicalRecords; }
+};
+
+void GOFFOstream::writeRecordPrefix(raw_ostream &OS, GOFF::RecordType Type,
+                                    size_t RemainingSize, uint8_t Flags) {
+  uint8_t TypeAndFlags = Flags | (Type << 4);
+  if (RemainingSize > GOFF::RecordLength)
+    TypeAndFlags |= Rec_Continued;
+  OS << binaryBe(static_cast<unsigned char>(GOFF::PTVPrefix))
+     << binaryBe(static_cast<unsigned char>(TypeAndFlags))
+     << binaryBe(static_cast<unsigned char>(0));
+}
+
+void GOFFOstream::newRecord(GOFF::RecordType Type, size_t Size) {
+  fillRecord();
+  CurrentType = Type;
+  RemainingSize = Size;
+  if (size_t Gap = (RemainingSize % GOFF::PayloadLength))
+    RemainingSize += GOFF::PayloadLength - Gap;
+  NewLogicalRecord = true;
+  ++LogicalRecords;
+}
+
+void GOFFOstream::fillRecord() {
+  assert((GetNumBytesInBuffer() <= RemainingSize) &&
+         "More bytes in buffer than expected");
+  size_t Remains = RemainingSize - GetNumBytesInBuffer();
+  if (Remains) {
+    assert((Remains < GOFF::RecordLength) &&
+           "Attempt to fill more than one physical record");
+    raw_ostream::write_zeros(Remains);
+  }
+  flush();
+  assert(RemainingSize == 0 && "Not fully flushed");
+  assert(GetNumBytesInBuffer() == 0 && "Buffer not fully empty");
+}
+
+void GOFFOstream::write_impl(const char *Ptr, size_t Size) {
+  assert((RemainingSize >= Size) && "Attempt to write too much data");
+  assert(RemainingSize && "Logical record overflow");
+  if (!(RemainingSize % GOFF::PayloadLength)) {
+    writeRecordPrefix(OS, CurrentType, RemainingSize,
+                      NewLogicalRecord ? 0 : Rec_Continuation);
+    NewLogicalRecord = false;
+  }
+  assert(!NewLogicalRecord &&
+         "New logical record not on physical record boundary");
+
+  size_t Idx = 0;
+  while (Size > 0) {
+    size_t BytesToWrite = bytesToNextPhysicalRecord();
+    if (BytesToWrite > Size)
+      BytesToWrite = Size;
+    OS.write(Ptr + Idx, BytesToWrite);
+    Idx += BytesToWrite;
+    Size -= BytesToWrite;
+    RemainingSize -= BytesToWrite;
+    if (Size) {
+      writeRecordPrefix(OS, CurrentType, RemainingSize);
+    }
+  }
+}
+
+class GOFFState {
+  void writeHeader(GOFFYAML::FileHeader &FileHdr);
+  void writeEnd();
+  void writeSymbol(GOFFYAML::Symbol Sym);
+  void writeSection(GOFFYAML::Section Sec);
+  void writeRelocationDirectory(GOFFYAML::Relocations Rel);
+
+  void reportError(const Twine &Msg) {
+    ErrHandler(Msg);
+    HasError = true;
+  }
+
+  GOFFState(raw_ostream &OS, GOFFYAML::Object &Doc,
+            yaml::ErrorHandler ErrHandler)
+      : GW(OS), Doc(Doc), ErrHandler(ErrHandler), SymbolID(0), HasError(false) {
+  }
+
+  ~GOFFState() { GW.finalize(); }
+
+  bool writeObject();
+
+public:
+  static bool writeGOFF(raw_ostream &OS, GOFFYAML::Object &Doc,
+                        yaml::ErrorHandler ErrHandler);
+
+private:
+  GOFFOstream GW;
+  GOFFYAML::Object &Doc;
+  yaml::ErrorHandler ErrHandler;
+  uint16_t SymbolID;
+  bool HasError;
+};
+
+void GOFFState::writeHeader(GOFFYAML::FileHeader &FileHdr) {
+  SmallString<16> CCSIDName;
+  if (std::error_code EC =
+          ConverterEBCDIC::convertToEBCDIC(FileHdr.CharacterSetName, CCSIDName))
+    reportError("Conversion error on " + FileHdr.CharacterSetName);
+  if (CCSIDName.size() > 16) {
+    reportError("CharacterSetName too long");
+    CCSIDName.resize(16);
+  }
+  SmallString<16> LangProd;
+  if (std::error_code EC = ConverterEBCDIC::convertToEBCDIC(
+          FileHdr.LanguageProductIdentifier, LangProd))
+    reportError("Conversion error on " + FileHdr.LanguageProductIdentifier);
+  if (LangProd.size() > 16) {
+    reportError("LanguageProductIdentifier too long");
+    LangProd.resize(16);
+  }
+
+  GW.newRecord(GOFF::RT_HDR, GOFF::PayloadLength);
+  GW << binaryBe(FileHdr.TargetEnvironment)     // TargetEnvironment
+     << binaryBe(FileHdr.TargetOperatingSystem) // TargetOperatingSystem
+     << zeros(2)                                // Reserved
+     << binaryBe(FileHdr.CCSID)                 // CCSID
+     << CCSIDName                               // CharacterSetName
+     << zeros(16 - CCSIDName.size())            // Fill bytes
+     << LangProd                                // LanguageProductIdentifier
+     << zeros(16 - LangProd.size())             // Fill bytes
+     << binaryBe(FileHdr.ArchitectureLevel);    // ArchitectureLevel
+  // The module propties are optional. Figure out if we need to write them
----------------
jh7370 wrote:

```suggestion
  // The module propties are optional. Figure out if we need to write them.
```

https://github.com/llvm/llvm-project/pull/71445