[TableGen][DecoderEmitter] Replace opcode mask with booleans (NFC) (#159113)

Extracted from #155889, which removes inclusion of `MCDecoderOps.h`.

Author: s-barannikov

llvm/utils/TableGen/DecoderEmitter.cpp

@@ -226,6 +226,9 @@ struct DecoderTableInfo {
   DecoderTable Table;
   PredicateSet Predicates;
   DecoderSet Decoders;
+  bool HasCheckPredicate;
+  bool HasSoftFail;
+  bool HasTryDecode;
 
   void insertPredicate(StringRef Predicate) {
     Predicates.insert(CachedHashString(Predicate));
@@ -266,11 +269,10 @@ class DecoderEmitter {
 
   const CodeGenTarget &getTarget() const { return Target; }
 
-  // Emit the decoder state machine table. Returns a mask of MCD decoder ops
-  // that were emitted.
-  unsigned emitTable(formatted_raw_ostream &OS, DecoderTable &Table,
-                     StringRef Namespace, unsigned HwModeID, unsigned BitWidth,
-                     ArrayRef<unsigned> EncodingIDs) const;
+  // Emit the decoder state machine table.
+  void emitTable(formatted_raw_ostream &OS, DecoderTableInfo &TableInfo,
+                 StringRef Namespace, unsigned HwModeID, unsigned BitWidth,
+                 ArrayRef<unsigned> EncodingIDs) const;
   void emitInstrLenTable(formatted_raw_ostream &OS,
                          ArrayRef<unsigned> InstrLen) const;
   void emitPredicateFunction(formatted_raw_ostream &OS,
@@ -629,12 +631,11 @@ static StringRef getDecoderOpName(DecoderOps Op) {
   llvm_unreachable("Unknown decoder op");
 }
 
-// Emit the decoder state machine table. Returns a mask of MCD decoder ops
-// that were emitted.
-unsigned DecoderEmitter::emitTable(formatted_raw_ostream &OS,
-                                   DecoderTable &Table, StringRef Namespace,
-                                   unsigned HwModeID, unsigned BitWidth,
-                                   ArrayRef<unsigned> EncodingIDs) const {
+// Emit the decoder state machine table.
+void DecoderEmitter::emitTable(formatted_raw_ostream &OS,
+                               DecoderTableInfo &TableInfo, StringRef Namespace,
+                               unsigned HwModeID, unsigned BitWidth,
+                               ArrayRef<unsigned> EncodingIDs) const {
   // We'll need to be able to map from a decoded opcode into the corresponding
   // EncodingID for this specific combination of BitWidth and Namespace. This
   // is used below to index into Encodings.
@@ -648,7 +649,7 @@ unsigned DecoderEmitter::emitTable(formatted_raw_ostream &OS,
   OS << "static const uint8_t DecoderTable" << Namespace;
   if (HwModeID != DefaultMode)
     OS << '_' << Target.getHwModes().getModeName(HwModeID);
-  OS << BitWidth << "[" << Table.size() << "] = {\n";
+  OS << BitWidth << "[" << TableInfo.Table.size() << "] = {\n";
 
   // Emit ULEB128 encoded value to OS, returning the number of bytes emitted.
   auto EmitULEB128 = [](DecoderTable::const_iterator &I,
@@ -678,6 +679,7 @@ unsigned DecoderEmitter::emitTable(formatted_raw_ostream &OS,
 
   // FIXME: We may be able to use the NumToSkip values to recover
   // appropriate indentation levels.
+  DecoderTable &Table = TableInfo.Table;
   DecoderTable::const_iterator I = Table.begin();
   DecoderTable::const_iterator E = Table.end();
   const uint8_t *const EndPtr = Table.data() + Table.size();
@@ -719,15 +721,12 @@ unsigned DecoderEmitter::emitTable(formatted_raw_ostream &OS,
     return Value;
   };
 
-  unsigned OpcodeMask = 0;
-
   while (I != E) {
     assert(I < E && "incomplete decode table entry!");
 
     uint32_t Pos = I - Table.begin();
     EmitPos(Pos);
     const uint8_t DecoderOp = *I++;
-    OpcodeMask |= (1 << DecoderOp);
     OS << getDecoderOpName(static_cast<DecoderOps>(DecoderOp)) << ", ";
     switch (DecoderOp) {
     default:
@@ -826,8 +825,6 @@ unsigned DecoderEmitter::emitTable(formatted_raw_ostream &OS,
     OS << '\n';
   }
   OS << "};\n\n";
-
-  return OpcodeMask;
 }
 
 void DecoderEmitter::emitInstrLenTable(formatted_raw_ostream &OS,
@@ -1114,6 +1111,7 @@ void DecoderTableBuilder::emitPredicateTableEntry(unsigned EncodingID) const {
 
   TableInfo.Table.insertOpcode(OPC_CheckPredicate);
   TableInfo.Table.insertULEB128(PredicateIndex);
+  TableInfo.HasCheckPredicate = true;
 }
 
 void DecoderTableBuilder::emitSoftFailTableEntry(unsigned EncodingID) const {
@@ -1130,6 +1128,7 @@ void DecoderTableBuilder::emitSoftFailTableEntry(unsigned EncodingID) const {
   TableInfo.Table.insertOpcode(OPC_SoftFail);
   TableInfo.Table.insertULEB128(PositiveMask.getZExtValue());
   TableInfo.Table.insertULEB128(NegativeMask.getZExtValue());
+  TableInfo.HasSoftFail = true;
 }
 
 // Emits table entries to decode the singleton.
@@ -1180,6 +1179,7 @@ void DecoderTableBuilder::emitSingletonTableEntry(
   const Record *InstDef = Encodings[EncodingID].getInstruction()->TheDef;
   TableInfo.Table.insertULEB128(Target.getInstrIntValue(InstDef));
   TableInfo.Table.insertULEB128(DecoderIndex);
+  TableInfo.HasTryDecode |= DecoderOp == OPC_TryDecode;
 }
 
 std::unique_ptr<Filter>
@@ -1523,11 +1523,7 @@ void DecoderTableBuilder::emitTableEntries(const FilterChooser &FC) const {
 // emitDecodeInstruction - Emit the templated helper function
 // decodeInstruction().
 static void emitDecodeInstruction(formatted_raw_ostream &OS, bool IsVarLenInst,
-                                  unsigned OpcodeMask) {
-  const bool HasTryDecode = OpcodeMask & (1 << OPC_TryDecode);
-  const bool HasCheckPredicate = OpcodeMask & (1 << OPC_CheckPredicate);
-  const bool HasSoftFail = OpcodeMask & (1 << OPC_SoftFail);
-
+                                  const DecoderTableInfo &TableInfo) {
   OS << R"(
 static unsigned decodeNumToSkip(const uint8_t *&Ptr) {
   unsigned NumToSkip = *Ptr++;
@@ -1548,7 +1544,7 @@ static DecodeStatus decodeInstruction(const uint8_t DecodeTable[], MCInst &MI,
           "llvm::function_ref<void(APInt &, uint64_t)> makeUp";
   }
   OS << ") {\n";
-  if (HasCheckPredicate)
+  if (TableInfo.HasCheckPredicate)
     OS << "  const FeatureBitset &Bits = STI.getFeatureBits();\n";
   OS << "  const uint8_t *Ptr = DecodeTable;\n";
 
@@ -1657,7 +1653,7 @@ static DecodeStatus decodeInstruction(const uint8_t DecodeTable[], MCInst &MI,
       }
       break;
     })";
-  if (HasCheckPredicate) {
+  if (TableInfo.HasCheckPredicate) {
     OS << R"(
     case OPC_CheckPredicate: {
       // Decode the Predicate Index value.
@@ -1701,7 +1697,7 @@ static DecodeStatus decodeInstruction(const uint8_t DecodeTable[], MCInst &MI,
                    << (S != MCDisassembler::Fail ? "PASS\n" : "FAIL\n"));
       return S;
     })";
-  if (HasTryDecode) {
+  if (TableInfo.HasTryDecode) {
     OS << R"(
     case OPC_TryDecode: {
       // Decode the Opcode value.
@@ -1735,7 +1731,7 @@ static DecodeStatus decodeInstruction(const uint8_t DecodeTable[], MCInst &MI,
       break;
     })";
   }
-  if (HasSoftFail) {
+  if (TableInfo.HasSoftFail) {
     OS << R"(
     case OPC_SoftFail: {
       // Decode the mask values.
@@ -1994,9 +1990,8 @@ template <typename T> constexpr uint32_t InsnBitWidth = 0;
 
   // Entries in `EncMap` are already sorted by bitwidth. So bucketing per
   // bitwidth can be done on-the-fly as we iterate over the map.
-  DecoderTableInfo TableInfo;
+  DecoderTableInfo TableInfo{};
   DecoderTableBuilder TableBuilder(Target, Encodings, TableInfo);
-  unsigned OpcodeMask = 0;
 
   bool HasConflict = false;
   for (const auto &[BitWidth, BWMap] : EncMap) {
@@ -2021,8 +2016,8 @@ template <typename T> constexpr uint32_t InsnBitWidth = 0;
       TableBuilder.buildTable(FC, BitWidth);
 
       // Print the table to the output stream.
-      OpcodeMask |= emitTable(OS, TableInfo.Table, DecoderNamespace, HwModeID,
-                              BitWidth, EncodingIDs);
+      emitTable(OS, TableInfo, DecoderNamespace, HwModeID, BitWidth,
+                EncodingIDs);
     }
 
     // Each BitWidth get's its own decoders and decoder function if
@@ -2041,14 +2036,12 @@ template <typename T> constexpr uint32_t InsnBitWidth = 0;
   if (!SpecializeDecodersPerBitwidth)
     emitDecoderFunction(OS, TableInfo.Decoders, 0);
 
-  const bool HasCheckPredicate = OpcodeMask & (1 << OPC_CheckPredicate);
-
   // Emit the predicate function.
-  if (HasCheckPredicate)
+  if (TableInfo.HasCheckPredicate)
     emitPredicateFunction(OS, TableInfo.Predicates);
 
   // Emit the main entry point for the decoder, decodeInstruction().
-  emitDecodeInstruction(OS, IsVarLenInst, OpcodeMask);
+  emitDecodeInstruction(OS, IsVarLenInst, TableInfo);
 
   OS << "\n} // namespace\n";
 }