[asm matcher] Fix incorrect assertion when there are exactly 32 SubtargetFeatures

[dsanders]

Summary

The minimal type needs to hold a value of '1ULL << 31' but
getMinimalTypeForRange() is called with a value of '1ULL << 32'.

This patch will also reduce the size of the matcher table when there are 8
or 16 SubtargetFeatures.

Also added a dump of the SubtargetFeatures to the -debug output and corrected getMinimalTypeInRange() to consider 0xffffffffull to be a 32-bit value.

The testcase is that no existing code is broken and that LLVM still successfully
compiles after adding MIPS64r6 CodeGen support.

[dsanders]

• Fix narrowing warnings using a strongly typed enum and correctly typed constant 1

[dsanders]

There is now a concrete test case. D3842 is the first patch that fails to compile without this.

[• rafael]

LGTM with a nit.

utils/TableGen/AsmMatcherEmitter.cpp

2209

If this is the maximum used value, the assert should be <=, no?

[dsanders]

Thanks. Committed in r209288 with the nit fixed.

utils/TableGen/AsmMatcherEmitter.cpp

struct SubtargetFeatureInfo {
   unsigned Index;
 
   SubtargetFeatureInfo(Record *D, unsigned Idx) : TheDef(D), Index(Idx) {}
 
   /// \brief The name of the enumerated constant identifying this feature.
   std::string getEnumName() const {
     return "Feature_" + TheDef->getName();
   }
+
+  void dump() {
+    errs() << getEnumName() << " " << Index << "\n";
+    TheDef->dump();
+  }
 };
 
 struct OperandMatchEntry {
   unsigned OperandMask;
   MatchableInfo* MI;
   ClassInfo *CI;
 
   static OperandMatchEntry create(MatchableInfo* mi, ClassInfo *ci,
for (unsigned i = 0, e = AllPredicates.size(); i != e; ++i) {
     if (!Pred->getValueAsBit("AssemblerMatcherPredicate"))
       continue;
 
     if (Pred->getName().empty())
       PrintFatalError(Pred->getLoc(), "Predicate has no name!");
 
     unsigned FeatureNo = SubtargetFeatures.size();
     SubtargetFeatures[Pred] = new SubtargetFeatureInfo(Pred, FeatureNo);
+    DEBUG(SubtargetFeatures[Pred]->dump());
     assert(FeatureNo < 32 && "Too many subtarget features!");
   }
 
   // Parse the instructions; we need to do this first so that we can gather the
   // singleton register classes.
   SmallPtrSet<Record*, 16> SingletonRegisters;
   unsigned VariantCount = Target.getAsmParserVariantCount();
   for (unsigned VC = 0; VC != VariantCount; ++VC) {
static void emitMatchRegisterName(CodeGenTarget &Target, Record *AsmParser,
   OS << "static unsigned MatchRegisterName(StringRef Name) {\n";
 
   StringMatcher("Name", Matches, OS).Emit();
 
   OS << "  return 0;\n";
   OS << "}\n\n";
 }
 
+static const char *getMinimalTypeForRange(uint64_t Range) {
+  assert(Range < 0xFFFFFFFFULL && "Enum too large");
+  if (Range > 0xFFFF)
+    return "uint32_t";
+  if (Range > 0xFF)
+    return "uint16_t";
+  return "uint8_t";
+}
+
+static const char *getMinimalRequiredFeaturesType(const AsmMatcherInfo &Info) {
+  uint64_t MaxIndex = Info.SubtargetFeatures.size();
+  if (MaxIndex > 0)
+    MaxIndex--;
+  return getMinimalTypeForRange(1ULL << MaxIndex);
+}
+
 /// emitSubtargetFeatureFlagEnumeration - Emit the subtarget feature flag
 /// definitions.
 static void emitSubtargetFeatureFlagEnumeration(AsmMatcherInfo &Info,
                                                 raw_ostream &OS) {
   OS << "// Flags for subtarget features that participate in "
      << "instruction matching.\n";
-  OS << "enum SubtargetFeatureFlag {\n";
+  OS << "enum SubtargetFeatureFlag : " << getMinimalRequiredFeaturesType(Info)
+     << " {\n";
   for (std::map<Record*, SubtargetFeatureInfo*, LessRecordByID>::const_iterator
          it = Info.SubtargetFeatures.begin(),
          ie = Info.SubtargetFeatures.end(); it != ie; ++it) {
     SubtargetFeatureInfo &SFI = *it->second;
-    OS << "  " << SFI.getEnumName() << " = (1 << " << SFI.Index << "),\n";
+    OS << "  " << SFI.getEnumName() << " = (1U << " << SFI.Index << "),\n";
   }
   OS << "  Feature_None = 0\n";
   OS << "};\n\n";
 }
 
 /// emitOperandDiagnosticTypes - Emit the operand matching diagnostic types.
 static void emitOperandDiagnosticTypes(AsmMatcherInfo &Info, raw_ostream &OS) {
   // Get the set of diagnostic types from all of the operand classes.
static bool emitMnemonicAliases(raw_ostream &OS, const AsmMatcherInfo &Info,
   // Emit aliases that apply to all variants.
   emitMnemonicAliasVariant(OS, Info, Aliases);
 
   OS << "}\n\n";
 
   return true;
 }
 
-static const char *getMinimalTypeForRange(uint64_t Range) {
-  assert(Range < 0xFFFFFFFFULL && "Enum too large");
-  if (Range > 0xFFFF)
-    return "uint32_t";
-  if (Range > 0xFF)
-    return "uint16_t";
-  return "uint8_t";
-}
-
 static void emitCustomOperandParsing(raw_ostream &OS, CodeGenTarget &Target,
                               const AsmMatcherInfo &Info, StringRef ClassName,
                               StringToOffsetTable &StringTable,
                               unsigned MaxMnemonicIndex) {
   unsigned MaxMask = 0;
   for (std::vector<OperandMatchEntry>::const_iterator it =
        Info.OperandMatchInfo.begin(), ie = Info.OperandMatchInfo.end();
        it != ie; ++it) {
     MaxMask |= it->OperandMask;
   }
 
   // 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";
   OS << "    " << getMinimalTypeForRange(Info.Classes.size())
                << " Class;\n";
   OS << "    " << getMinimalTypeForRange(MaxMask)
                << " OperandMask;\n\n";
   OS << "    StringRef getMnemonic() const {\n";
void AsmMatcherEmitter::run(raw_ostream &OS) {
   // following the mnemonic.
   OS << "namespace {\n";
   OS << "  struct MatchEntry {\n";
   OS << "    " << getMinimalTypeForRange(MaxMnemonicIndex)
                << " Mnemonic;\n";
   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";
   OS << "    StringRef getMnemonic() const {\n";
   OS << "      return StringRef(MnemonicTable + Mnemonic + 1,\n";
   OS << "                       MnemonicTable[Mnemonic]);\n";
   OS << "    }\n";
   OS << "  };\n\n";