[clang] [clang][DebugInfo] Emit DW_AT_language_{name, version} for DWARFv6 (PR #163208)

[David Blaikie via cfe-commits]

================
@@ -647,6 +647,77 @@ StringRef CGDebugInfo::getCurrentDirname() {
   return CGM.getCodeGenOpts().DebugCompilationDir;
 }
 
+static llvm::dwarf::SourceLanguage GetSourceLanguage(const CodeGenModule &CGM) {
+  const CodeGenOptions &CGO = CGM.getCodeGenOpts();
+  const LangOptions &LO = CGM.getLangOpts();
+
+  assert(CGO.DwarfVersion <= 5);
+
+  llvm::dwarf::SourceLanguage LangTag;
+  if (LO.CPlusPlus) {
+    if (LO.ObjC)
+      LangTag = llvm::dwarf::DW_LANG_ObjC_plus_plus;
+    else if (CGO.DebugStrictDwarf && CGO.DwarfVersion < 5)
+      LangTag = llvm::dwarf::DW_LANG_C_plus_plus;
+    else if (LO.CPlusPlus14)
+      LangTag = llvm::dwarf::DW_LANG_C_plus_plus_14;
+    else if (LO.CPlusPlus11)
+      LangTag = llvm::dwarf::DW_LANG_C_plus_plus_11;
+    else
+      LangTag = llvm::dwarf::DW_LANG_C_plus_plus;
+  } else if (LO.ObjC) {
+    LangTag = llvm::dwarf::DW_LANG_ObjC;
+  } else if (LO.OpenCL && (!CGO.DebugStrictDwarf || CGO.DwarfVersion >= 5)) {
+    LangTag = llvm::dwarf::DW_LANG_OpenCL;
+  } else if (LO.C11 && !(CGO.DebugStrictDwarf && CGO.DwarfVersion < 5)) {
+    LangTag = llvm::dwarf::DW_LANG_C11;
+  } else if (LO.C99) {
+    LangTag = llvm::dwarf::DW_LANG_C99;
+  } else {
+    LangTag = llvm::dwarf::DW_LANG_C89;
+  }
+
+  return LangTag;
+}
+
+static std::pair<llvm::dwarf::SourceLanguageName, uint32_t>
+GetSourceLanguageName(const CodeGenModule &CGM) {
+  const CodeGenOptions &CGO = CGM.getCodeGenOpts();
+  const LangOptions &LO = CGM.getLangOpts();
+
+  assert(CGO.DwarfVersion >= 6);
+
+  uint32_t LangVersion = 0;
+  llvm::dwarf::SourceLanguageName LangTag;
+  if (LO.CPlusPlus) {
+    if (LO.ObjC) {
+      LangTag = llvm::dwarf::DW_LNAME_ObjC_plus_plus;
+    } else {
+      LangTag = llvm::dwarf::DW_LNAME_C_plus_plus;
+      LangVersion = LO.getCPlusPlusLangStd().value_or(0);
+    }
+  } else if (LO.ObjC) {
+    LangTag = llvm::dwarf::DW_LNAME_ObjC;
+  } else if (LO.OpenCL) {
+    LangTag = llvm::dwarf::DW_LNAME_OpenCL_C;
+  } else {
+    LangTag = llvm::dwarf::DW_LNAME_C;
+    LangVersion = LO.getCLangStd().value_or(0);
+  }
+
+  return {LangTag, LangVersion};
+}
+
+static llvm::DISourceLanguageName
+GetDISourceLanguageName(const CodeGenModule &CGM) {
+  // Emit pre-DWARFv6 language codes.
+  if (CGM.getCodeGenOpts().DwarfVersion < 6)
+    return llvm::DISourceLanguageName(GetSourceLanguage(CGM));
+
+  auto [LName, LVersion] = GetSourceLanguageName(CGM);
----------------
dwblaikie wrote:

Maybe inline `GetSourceLanguageName` here - since this is the only caller & doesn't seem much benefit to having a std::pair result that then has to be remapped into the DISourceLanguageName.

https://github.com/llvm/llvm-project/pull/163208