[GOFF] Refactor writing GOFF records

A GOFF file is basically a sequence of records. Change the YAML mapping for GOFF files to reflect this. As result, creating files for testing, e.g. without a module header, becomes possible.

Author: redstar

Diff for: llvm/include/llvm/ObjectYAML/GOFFYAML.h

@@ -25,25 +25,87 @@ namespace llvm {
 // to use yaml::IO, we use these structures which are closer to the source.
 namespace GOFFYAML {
 
-struct FileHeader {
-  uint32_t TargetEnvironment = 0;
-  uint32_t TargetOperatingSystem = 0;
-  uint16_t CCSID = 0;
-  StringRef CharacterSetName;
-  StringRef LanguageProductIdentifier;
-  uint32_t ArchitectureLevel = 0;
-  std::optional<uint16_t> InternalCCSID;
-  std::optional<uint8_t> TargetSoftwareEnvironment;
+LLVM_YAML_STRONG_TYPEDEF(uint8_t, GOFF_AMODE)
+LLVM_YAML_STRONG_TYPEDEF(uint8_t, GOFF_ENDFLAGS)
+
+// The GOFF format uses different kinds of logical records. The format imposes
+// some rules on those records (e.g. the module header must come first, no
+// forward references to records, etc.). However, to be able to specify invalid
+// GOFF files, we treat all records the same way.
+struct RecordBase {
+  enum RecordBaseKind {
+    RBK_ModuleHeader,
+    RBK_RelocationDirectory,
+    RBK_Symbol,
+    RBK_Text,
+    RBK_DeferredLength,
+    RBK_EndOfModule
+  };
+
+private:
+  const RecordBaseKind Kind;
+
+protected:
+  RecordBase(RecordBaseKind Kind) : Kind(Kind) {}
+
+public:
+  RecordBaseKind getKind() const { return Kind; }
+};
+using RecordPtr = std::unique_ptr<RecordBase>;
+
+struct ModuleHeader : public RecordBase {
+  ModuleHeader() : RecordBase(RBK_ModuleHeader) {}
+
+  uint32_t ArchitectureLevel;
+  uint16_t PropertiesLength;
+  std::optional<yaml::BinaryRef> Properties;
+
+  static bool classof(const RecordBase *S) {
+    return S->getKind() == RBK_ModuleHeader;
+  }
+};
+
+struct EndOfModule : public RecordBase {
+  EndOfModule() : RecordBase(RBK_EndOfModule) {}
+
+  GOFF_ENDFLAGS Flags;
+  GOFF_AMODE AMODE;
+  uint32_t RecordCount;
+  uint32_t ESDID;
+  uint32_t Offset;
+  uint16_t NameLength;
+  StringRef EntryName;
+
+  static bool classof(const RecordBase *S) {
+    return S->getKind() == RBK_EndOfModule;
+  }
 };
 
 struct Object {
-  FileHeader Header;
-  Object();
+  // A GOFF file is a sequence of records.
+  std::vector<RecordPtr> Records;
 };
 } // end namespace GOFFYAML
 } // end namespace llvm
 
-LLVM_YAML_DECLARE_MAPPING_TRAITS(GOFFYAML::FileHeader)
+LLVM_YAML_DECLARE_ENUM_TRAITS(GOFFYAML::GOFF_AMODE)
+LLVM_YAML_DECLARE_ENUM_TRAITS(GOFFYAML::GOFF_ENDFLAGS)
+
+LLVM_YAML_IS_SEQUENCE_VECTOR(GOFFYAML::RecordPtr)
+LLVM_YAML_DECLARE_MAPPING_TRAITS(GOFFYAML::RecordPtr)
+
+LLVM_YAML_DECLARE_MAPPING_TRAITS(GOFFYAML::ModuleHeader)
+LLVM_YAML_DECLARE_MAPPING_TRAITS(GOFFYAML::EndOfModule)
 LLVM_YAML_DECLARE_MAPPING_TRAITS(GOFFYAML::Object)
 
+namespace llvm {
+namespace yaml {
+
+template <> struct CustomMappingTraits<GOFFYAML::RecordPtr> {
+  static void inputOne(IO &IO, StringRef Key, GOFFYAML::RecordPtr &Elem);
+  static void output(IO &IO, GOFFYAML::RecordPtr &Elem);
+};
+
+} // namespace yaml
+} // namespace llvm
 #endif // LLVM_OBJECTYAML_GOFFYAML_H