[llvm][DebugInfo] Add support for emitting DW_AT_language_name

llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp

@@ -569,7 +569,40 @@ void CodeViewDebug::emitCodeViewMagicVersion() {
   OS.emitInt32(COFF::DEBUG_SECTION_MAGIC);
 }
 
-static SourceLanguage MapDWLangToCVLang(unsigned DWLang) {
+static SourceLanguage
+MapDWARFLanguageToCVLang(dwarf::SourceLanguageName DWLName) {
+  switch (DWLName) {
+  case dwarf::DW_LNAME_C:
+    return SourceLanguage::C;
+  case dwarf::DW_LNAME_C_plus_plus:
+    return SourceLanguage::Cpp;
+  case dwarf::DW_LNAME_Fortran:
+    return SourceLanguage::Fortran;
+  case dwarf::DW_LNAME_Pascal:
+    return SourceLanguage::Pascal;
+  case dwarf::DW_LNAME_Cobol:
+    return SourceLanguage::Cobol;
+  case dwarf::DW_LNAME_Java:
+    return SourceLanguage::Java;
+  case dwarf::DW_LNAME_D:
+    return SourceLanguage::D;
+  case dwarf::DW_LNAME_Swift:
+    return SourceLanguage::Swift;
+  case dwarf::DW_LNAME_Rust:
+    return SourceLanguage::Rust;
+  case dwarf::DW_LNAME_ObjC:
+    return SourceLanguage::ObjC;
+  case dwarf::DW_LNAME_ObjC_plus_plus:
+    return SourceLanguage::ObjCpp;
+  default:
+    // There's no CodeView representation for this language, and CV doesn't
+    // have an "unknown" option for the language field, so we'll use MASM,
+    // as it's very low level.
+    return SourceLanguage::Masm;
+  }
+}
+
+static SourceLanguage MapDWARFLanguageToCVLang(dwarf::SourceLanguage DWLang) {
   switch (DWLang) {
   case dwarf::DW_LANG_C:
   case dwarf::DW_LANG_C89:
@@ -633,8 +666,13 @@ void CodeViewDebug::beginModule(Module *M) {
     Node = *CUs->operands().begin();
   }
   const auto *CU = cast<DICompileUnit>(Node);
+  DISourceLanguageName Lang = CU->getSourceLanguage();
   CurrentSourceLanguage =
-      MapDWLangToCVLang(CU->getSourceLanguage().getUnversionedName());
+      Lang.hasVersionedName()
+          ? MapDWARFLanguageToCVLang(
+                static_cast<dwarf::SourceLanguageName>(Lang.getName()))
+          : MapDWARFLanguageToCVLang(
+                static_cast<dwarf::SourceLanguage>(Lang.getName()));
   if (!M->getCodeViewFlag() ||
       CU->getEmissionKind() == DICompileUnit::NoDebug) {
     Asm = nullptr;

llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp

@@ -1039,8 +1039,12 @@ void DwarfDebug::finishUnitAttributes(const DICompileUnit *DIUnit,
   } else
     NewCU.addString(Die, dwarf::DW_AT_producer, Producer);
 
-  NewCU.addUInt(Die, dwarf::DW_AT_language, dwarf::DW_FORM_data2,
-                DIUnit->getSourceLanguage().getUnversionedName());
+  if (auto Lang = DIUnit->getSourceLanguage(); Lang.hasVersionedName())
+    NewCU.addUInt(Die, dwarf::DW_AT_language_name, dwarf::DW_FORM_data2,
+                  Lang.getName());
+  else
+    NewCU.addUInt(Die, dwarf::DW_AT_language, dwarf::DW_FORM_data2,
+                  Lang.getName());
 
   NewCU.addString(Die, dwarf::DW_AT_name, FN);
   StringRef SysRoot = DIUnit->getSysRoot();

llvm/test/DebugInfo/Generic/compileunit-source-language-name.ll

@@ -0,0 +1,20 @@
+; RUN: %llc_dwarf -filetype=obj -O0 < %s | llvm-dwarfdump -debug-info - | FileCheck %s --implicit-check-not "DW_AT_language"
+
+; CHECK: DW_AT_language_name (DW_LNAME_ObjC_plus_plus)
+
+source_filename = "cu.cpp"
+target triple = "arm64-apple-macosx"
+
+@x = global i32 0, align 4, !dbg !0
+
+!llvm.dbg.cu = !{!2}
+!llvm.module.flags = !{!6, !7}
+
+!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
+!1 = !DIGlobalVariable(name: "x", scope: !2, file: !3, line: 1, type: !5, isLocal: false, isDefinition: true)
+!2 = distinct !DICompileUnit(sourceLanguageName: DW_LNAME_ObjC_plus_plus, file: !3, producer: "handwritten", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, globals: !4, splitDebugInlining: false, nameTableKind: Apple, sysroot: "/")
+!3 = !DIFile(filename: "cu.cpp", directory: "/tmp")
+!4 = !{!0}
+!5 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!6 = !{i32 7, !"Dwarf Version", i32 5}
+!7 = !{i32 2, !"Debug Info Version", i32 3}

llvm/test/DebugInfo/Generic/compileunit-source-language.ll

@@ -0,0 +1,20 @@
+; RUN: %llc_dwarf -filetype=obj -O0 < %s | llvm-dwarfdump -debug-info - | FileCheck %s --implicit-check-not "DW_AT_language_name"
+
+; CHECK: DW_AT_language (DW_LANG_C)
+
+source_filename = "cu.cpp"
+target triple = "arm64-apple-macosx"
+
+@x = global i32 0, align 4, !dbg !0
+
+!llvm.dbg.cu = !{!2}
+!llvm.module.flags = !{!6, !7}
+
+!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
+!1 = !DIGlobalVariable(name: "x", scope: !2, file: !3, line: 1, type: !5, isLocal: false, isDefinition: true)
+!2 = distinct !DICompileUnit(language: DW_LANG_C, file: !3, producer: "handwritten", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, globals: !4, splitDebugInlining: false, nameTableKind: Apple, sysroot: "/")
+!3 = !DIFile(filename: "cu.cpp", directory: "/tmp")
+!4 = !{!0}
+!5 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!6 = !{i32 7, !"Dwarf Version", i32 5}
+!7 = !{i32 2, !"Debug Info Version", i32 3}