[llvm] [z/OS][GOFF] Implement support for writing ESD + TXT records by the GOFFObjectWriter (PR #85851)

[Ulrich Weigand via llvm-commits]

================
@@ -259,6 +633,411 @@ void GOFFObjectWriter::writeHeader() {
   OS.write_zeros(6);       // Reserved
 }
 
+void GOFFObjectWriter::writeSymbol(const GOFFSymbol &Symbol,
+                                   const MCAsmLayout &Layout) {
+  uint32_t Offset = 0;
+  uint32_t Length = 0;
+  GOFF::ESDNameSpaceId NameSpaceId = GOFF::ESD_NS_ProgramManagementBinder;
+  Flags SymbolFlags;
+  uint8_t FillByteValue = 0;
+
+  Flags BehavAttrs[10] = {};
+  auto setAmode = [&BehavAttrs](GOFF::ESDAmode Amode) {
+    BehavAttrs[0].set(0, 8, Amode);
+  };
+  auto setRmode = [&BehavAttrs](GOFF::ESDRmode Rmode) {
+    BehavAttrs[1].set(0, 8, Rmode);
+  };
+  auto setTextStyle = [&BehavAttrs](GOFF::ESDTextStyle Style) {
+    BehavAttrs[2].set(0, 4, Style);
+  };
+  auto setBindingAlgorithm =
+      [&BehavAttrs](GOFF::ESDBindingAlgorithm Algorithm) {
+        BehavAttrs[2].set(4, 4, Algorithm);
+      };
+  auto setTaskingBehavior =
+      [&BehavAttrs](GOFF::ESDTaskingBehavior TaskingBehavior) {
+        BehavAttrs[3].set(0, 3, TaskingBehavior);
+      };
+  auto setReadOnly = [&BehavAttrs](bool ReadOnly) {
+    BehavAttrs[3].set(4, 1, ReadOnly);
+  };
+  auto setExecutable = [&BehavAttrs](GOFF::ESDExecutable Executable) {
+    BehavAttrs[3].set(5, 3, Executable);
+  };
+  auto setDuplicateSeverity =
+      [&BehavAttrs](GOFF::ESDDuplicateSymbolSeverity DSS) {
+        BehavAttrs[4].set(2, 2, DSS);
+      };
+  auto setBindingStrength = [&BehavAttrs](GOFF::ESDBindingStrength Strength) {
+    BehavAttrs[4].set(4, 4, Strength);
+  };
+  auto setLoadingBehavior = [&BehavAttrs](GOFF::ESDLoadingBehavior Behavior) {
+    BehavAttrs[5].set(0, 2, Behavior);
+  };
+  auto setIndirectReference = [&BehavAttrs](bool Indirect) {
+    uint8_t Value = Indirect ? 1 : 0;
+    BehavAttrs[5].set(3, 1, Value);
+  };
+  auto setBindingScope = [&BehavAttrs](GOFF::ESDBindingScope Scope) {
+    BehavAttrs[5].set(4, 4, Scope);
+  };
+  auto setLinkageType = [&BehavAttrs](GOFF::ESDLinkageType Type) {
+    BehavAttrs[6].set(2, 1, Type);
+  };
+  auto setAlignment = [&BehavAttrs](GOFF::ESDAlignment Alignment) {
+    BehavAttrs[6].set(3, 5, Alignment);
+  };
+
+  uint32_t AdaEsdId = 0;
+  uint32_t SortPriority = 0;
+
+  switch (Symbol.SymbolType) {
+  case GOFF::ESD_ST_SectionDefinition: {
+    if (Symbol.isExecutable()) // Unspecified otherwise
+      setTaskingBehavior(GOFF::ESD_TA_Rent);
+    if (Symbol.BindingScope == GOFF::ESD_BSC_Section)
+      setBindingScope(Symbol.BindingScope);
+  } break;
+  case GOFF::ESD_ST_ElementDefinition: {
+    SymbolFlags.set(3, 1, Symbol.isRemovable()); // Removable
+    if (Symbol.isExecutable()) {
+      setExecutable(GOFF::ESD_EXE_CODE);
+      setReadOnly(true);
+    } else {
+      if (Symbol.isExecUnspecified())
+        setExecutable(GOFF::ESD_EXE_Unspecified);
+      else
+        setExecutable(GOFF::ESD_EXE_DATA);
+
+      if (Symbol.isForceRent() || Symbol.isReadOnly()) // TODO
+        setReadOnly(true);
+    }
+    Offset = 0; // TODO ED and SD are 1-1 for now
+    setAlignment(Symbol.Alignment);
+    SymbolFlags.set(0, 1, 1); // Fill-Byte Value Presence Flag
+    FillByteValue = 0;
+    SymbolFlags.set(1, 1, 0); // Mangled Flag TODO ?
+    setAmode(Symbol.Amode);
+    setRmode(Symbol.Rmode);
+    setTextStyle(Symbol.TextStyle);
+    setBindingAlgorithm(Symbol.BindAlgorithm);
+    setLoadingBehavior(Symbol.LoadBehavior);
+    SymbolFlags.set(5, 3, GOFF::ESD_RQ_0); // Reserved Qwords
+    if (Symbol.isForceRent())
+      setReadOnly(true);
+    NameSpaceId = Symbol.NameSpace;
+    Length = Symbol.SectionLength;
+    break;
+  }
+  case GOFF::ESD_ST_LabelDefinition: {
+    if (Symbol.isExecutable())
+      setExecutable(GOFF::ESD_EXE_CODE);
+    else
+      setExecutable(GOFF::ESD_EXE_DATA);
+    setBindingStrength(Symbol.BindingStrength);
+    setLinkageType(Symbol.Linkage);
+    SymbolFlags.set(2, 1, Symbol.Renamable); // Renamable;
+    setAmode(Symbol.Amode);
+    NameSpaceId = Symbol.NameSpace;
+    setBindingScope(Symbol.BindingScope);
+    AdaEsdId = Symbol.ADAEsdId;
+
+    // Only symbol that doesn't have an MC is the SectionLabelSymbol which
+    // implicitly has 0 offset into the parent SD!
+    if (auto *MCSym = Symbol.MCSym) {
+      uint64_t Ofs = Layout.getSymbolOffset(*MCSym);
----------------
uweigand wrote:

Why do we have to keep track of the MCSym pointer until here?  Couldn't we have retrieved the Offset when creating the GOFFSymbol already?

https://github.com/llvm/llvm-project/pull/85851