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

[James Henderson via llvm-commits]

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+//===- 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.
----------------
jh7370 wrote:

```suggestion
  /// Signals start of new record.
```

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