[AArch64] remove pointless AEK_NONE (#97569)

Author: tmatheson-arm

llvm/unittests/TargetParser/TargetParserTest.cpp

@@ -68,11 +68,6 @@ std::string FormatExtensionFlags(int64_t Flags) {
 
 std::string FormatExtensionFlags(AArch64::ExtensionBitset Flags) {
   std::vector<StringRef> Features;
-
-  // AEK_NONE is not meant to be shown to the user so the target parser
-  // does not recognise it. It is relevant here though.
-  if (Flags.test(AArch64::AEK_NONE))
-    Features.push_back("none");
   AArch64::getExtensionFeatures(Flags, Features);
 
   // The target parser also includes every extension you don't have.
@@ -2009,10 +2004,9 @@ TEST(TargetParserTest, AArch64ExtensionFeatures) {
   for (auto Ext : Extensions)
     ExtVal.set(Ext);
 
-  // NONE has no feature names.
-  // We return True here because NONE is a valid choice.
-  EXPECT_TRUE(AArch64::getExtensionFeatures({AArch64::AEK_NONE}, Features));
-  EXPECT_TRUE(!Features.size());
+  // Test an empty set of features.
+  EXPECT_TRUE(AArch64::getExtensionFeatures({}, Features));
+  EXPECT_TRUE(Features.size() == 0);
 
   AArch64::getExtensionFeatures(ExtVal, Features);
   EXPECT_EQ(Extensions.size(), Features.size());
@@ -2092,8 +2086,7 @@ TEST(TargetParserTest, AArch64ExtensionFeatures) {
   EXPECT_TRUE(llvm::is_contained(Features, "+complxnum"));
 
   // Assuming we listed every extension above, this should produce the same
-  // result. (note that AEK_NONE doesn't have a name so it won't be in the
-  // result despite its bit being set)
+  // result.
   std::vector<StringRef> AllFeatures;
   EXPECT_TRUE(AArch64::getExtensionFeatures(ExtVal, AllFeatures));
   EXPECT_THAT(Features, ::testing::ContainerEq(AllFeatures));

llvm/utils/TableGen/ARMTargetDefEmitter.cpp

@@ -78,12 +78,10 @@ static void EmitARMTargetDef(RecordKeeper &RK, raw_ostream &OS) {
 
   // Emit the ArchExtKind enum
   OS << "#ifdef EMIT_ARCHEXTKIND_ENUM\n"
-     << "enum ArchExtKind : unsigned {\n"
-     << "  AEK_NONE = 1,\n";
+     << "enum ArchExtKind : unsigned {\n";
   for (const Record *Rec : SortedExtensions) {
     auto AEK = Rec->getValueAsString("ArchExtKindSpelling").upper();
-    if (AEK != "AEK_NONE")
-      OS << "  " << AEK << ",\n";
+    OS << "  " << AEK << ",\n";
   }
   OS << "  AEK_NUM_EXTENSIONS\n"
      << "};\n"
@@ -108,7 +106,6 @@ static void EmitARMTargetDef(RecordKeeper &RK, raw_ostream &OS) {
     OS << ", \"-" << Rec->getValueAsString("Name") << "\""; // negfeature
     OS << "},\n";
   };
-  OS << "  {\"none\", {}, AArch64::AEK_NONE, {}, {}, {}, {} },\n";
   OS << "};\n"
      << "#undef EMIT_EXTENSIONS\n"
      << "#endif // EMIT_EXTENSIONS\n"