Index: utils/TableGen/AsmMatcherEmitter.cpp
===================================================================
--- utils/TableGen/AsmMatcherEmitter.cpp
+++ utils/TableGen/AsmMatcherEmitter.cpp
@@ -573,6 +573,11 @@
   std::string getEnumName() const {
     return "Feature_" + TheDef->getName();
   }
+
+  void dump() {
+    errs() << getEnumName() << " " << Index << "\n";
+    TheDef->dump();
+  }
 };
 
 struct OperandMatchEntry {
@@ -1324,6 +1329,7 @@
 
     unsigned FeatureNo = SubtargetFeatures.size();
     SubtargetFeatures[Pred] = new SubtargetFeatureInfo(Pred, FeatureNo);
+    DEBUG(SubtargetFeatures[Pred]->dump());
     assert(FeatureNo < 32 && "Too many subtarget features!");
   }
 
@@ -2454,6 +2460,13 @@
   return "uint8_t";
 }
 
+static const char *getMinimalRequiredFeaturesType(const AsmMatcherInfo &Info) {
+  uint64_t MaxIndex = Info.SubtargetFeatures.size();
+  if (MaxIndex > 0)
+    MaxIndex--;
+  return getMinimalTypeForRange(1ULL << MaxIndex);
+}
+
 static void emitCustomOperandParsing(raw_ostream &OS, CodeGenTarget &Target,
                               const AsmMatcherInfo &Info, StringRef ClassName,
                               StringToOffsetTable &StringTable,
@@ -2468,7 +2481,7 @@
   // Emit the static custom operand parsing table;
   OS << "namespace {\n";
   OS << "  struct OperandMatchEntry {\n";
-  OS << "    " << getMinimalTypeForRange(1ULL << Info.SubtargetFeatures.size())
+  OS << "    " << getMinimalRequiredFeaturesType(Info)
                << " RequiredFeatures;\n";
   OS << "    " << getMinimalTypeForRange(MaxMnemonicIndex)
                << " Mnemonic;\n";
@@ -2804,7 +2817,7 @@
   OS << "    uint16_t Opcode;\n";
   OS << "    " << getMinimalTypeForRange(Info.Matchables.size())
                << " ConvertFn;\n";
-  OS << "    " << getMinimalTypeForRange(1ULL << Info.SubtargetFeatures.size())
+  OS << "    " << getMinimalRequiredFeaturesType(Info)
                << " RequiredFeatures;\n";
   OS << "    " << getMinimalTypeForRange(Info.Classes.size())
                << " Classes[" << MaxNumOperands << "];\n";