[llvm][Dwarf] Add DW_LNAME_ string/enum getters

These are going to be used in a follow-up patch. And they are generally
useful for consumers (we have these for most other attributes).

(cherry picked from commit ddb4a2d)

Author: Michael137

llvm/include/llvm/BinaryFormat/Dwarf.h

@@ -997,6 +997,7 @@ LLVM_ABI StringRef VisibilityString(unsigned Visibility);
 LLVM_ABI StringRef VirtualityString(unsigned Virtuality);
 LLVM_ABI StringRef EnumKindString(unsigned EnumKind);
 LLVM_ABI StringRef LanguageString(unsigned Language);
+LLVM_ABI StringRef SourceLanguageNameString(SourceLanguageName Lang);
 LLVM_ABI StringRef CaseString(unsigned Case);
 LLVM_ABI StringRef ConventionString(unsigned Convention);
 LLVM_ABI StringRef InlineCodeString(unsigned Code);
@@ -1038,6 +1039,7 @@ LLVM_ABI unsigned getSubOperationEncoding(unsigned OpEncoding,
 LLVM_ABI unsigned getVirtuality(StringRef VirtualityString);
 LLVM_ABI unsigned getEnumKind(StringRef EnumKindString);
 LLVM_ABI unsigned getLanguage(StringRef LanguageString);
+LLVM_ABI unsigned getSourceLanguageName(StringRef SourceLanguageNameString);
 LLVM_ABI unsigned getCallingConvention(StringRef LanguageString);
 LLVM_ABI unsigned getAttributeEncoding(StringRef EncodingString);
 LLVM_ABI unsigned getMacinfo(StringRef MacinfoString);

llvm/lib/BinaryFormat/Dwarf.cpp

@@ -472,6 +472,26 @@ StringRef llvm::dwarf::LanguageDescription(dwarf::SourceLanguageName lname) {
   return "Unknown";
 }
 
+llvm::StringRef llvm::dwarf::SourceLanguageNameString(SourceLanguageName Lang) {
+  switch (Lang) {
+#define HANDLE_DW_LNAME(ID, NAME, DESC, LOWER_BOUND)                           \
+  case DW_LNAME_##NAME:                                                        \
+    return "DW_LNAME_" #NAME;
+#include "llvm/BinaryFormat/Dwarf.def"
+  }
+
+  return {};
+}
+
+unsigned
+llvm::dwarf::getSourceLanguageName(StringRef SourceLanguageNameString) {
+  return StringSwitch<unsigned>(SourceLanguageNameString)
+#define HANDLE_DW_LNAME(ID, NAME, DESC, LOWER_BOUND)                           \
+  .Case("DW_LNAME_" #NAME, DW_LNAME_##NAME)
+#include "llvm/BinaryFormat/Dwarf.def"
+      .Default(0);
+}
+
 StringRef llvm::dwarf::CaseString(unsigned Case) {
   switch (Case) {
   case DW_ID_case_sensitive:

llvm/unittests/BinaryFormat/DwarfTest.cpp

@@ -219,4 +219,39 @@ TEST(DwarfTest, lname) {
   EXPECT_EQ(roundtrip(DW_LANG_##NAME), DW_LANG_##NAME);
 #include "llvm/BinaryFormat/Dwarf.def"
 }
+
+TEST(DwarfTest, lname_getSourceLanguageName) {
+  // Some basics.
+  EXPECT_EQ(getSourceLanguageName("DW_LNAME_Ada"), DW_LNAME_Ada);
+  EXPECT_EQ(getSourceLanguageName("DW_LNAME_Metal"), DW_LNAME_Metal);
+
+  // Test invalid input.
+  EXPECT_EQ(getSourceLanguageName(""), 0U);
+  EXPECT_EQ(getSourceLanguageName("blah"), 0U);
+  EXPECT_EQ(getSourceLanguageName("DW_LNAME__something_unlikely"), 0U);
+  EXPECT_EQ(getSourceLanguageName("DW_LANG_C"), 0U);
+
+  // Test that we cover all DW_LNAME_ names.
+#define xstr(X) #X
+#define HANDLE_DW_LNAME(ID, NAME, DESC, LOWER_BOUND)                           \
+  EXPECT_EQ(getSourceLanguageName(xstr(DW_LNAME_##NAME)), DW_LNAME_##NAME);
+#include "llvm/BinaryFormat/Dwarf.def"
+}
+
+TEST(DwarfTest, lname_SourceLanguageNameString) {
+  // Some basics.
+  EXPECT_EQ(SourceLanguageNameString(DW_LNAME_C_plus_plus),
+            "DW_LNAME_C_plus_plus");
+  EXPECT_EQ(SourceLanguageNameString(DW_LNAME_CPP_for_OpenCL),
+            "DW_LNAME_CPP_for_OpenCL");
+
+  // Test invalid input.
+  EXPECT_EQ(SourceLanguageNameString(static_cast<SourceLanguageName>(0)), "");
+
+  // Test that we cover all DW_LNAME_ names.
+#define xstr(X) #X
+#define HANDLE_DW_LNAME(ID, NAME, DESC, LOWER_BOUND)                           \
+  EXPECT_EQ(SourceLanguageNameString(DW_LNAME_##NAME), xstr(DW_LNAME_##NAME));
+#include "llvm/BinaryFormat/Dwarf.def"
+}
 } // end namespace