[TableGen] Modify the AsmMatcherEmitter to only apply the table growth from r252440 to the Hexagon target.

This restores the previous behavior of not including the mnemonic in the classes table for every target that starts instruction lines with the mnemonic. Not only did the table size increase by 1 entry, but the class enum increased in size which caused every class in the array to increase in size. It also grew the size of the function that parsers tokens into classes by a substantial amount.

This adds a new HasMnemonicFirst flag to all AsmParsers. It's set to 1 by default and Hexagon target overrides it to 0.

For the X86 target alone this recovers 324KB of size on the llvm-mc executable.

I believe the current state is still a bad design choice for the Hexagon target as it causes most of the parsing to do a linear search through the entire match table to comparing operands against every instruction until it finds one that works. At least for the other targets we do a binary search based on mnemonic over which to do the linear scan.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@256669 91177308-0d34-0410-b5e6-96231b3b80d8

Author: topperc

include/llvm/Target/Target.td

@@ -936,6 +936,10 @@ class AsmParser {
   // ShouldEmitMatchRegisterName - Set to false if the target needs a hand
   // written register name matcher
   bit ShouldEmitMatchRegisterName = 1;
+
+  // HasMnemonicFirst - Set to false if target instructions don't always
+  // start with a mnemonic as the first token.
+  bit HasMnemonicFirst = 1;
 }
 def DefaultAsmParser : AsmParser;
 

lib/Target/Hexagon/Hexagon.td

@@ -251,6 +251,10 @@ def : Proc<"hexagonv60", HexagonModelV60,
 // Declare the target which we are implementing
 //===----------------------------------------------------------------------===//
 
+def HexagonAsmParser : AsmParser {
+  bit HasMnemonicFirst = 0;
+}
+
 def HexagonAsmParserVariant : AsmParserVariant {
   int Variant = 0;
   string TokenizingCharacters = "#()=:.<>!+*";
@@ -259,5 +263,6 @@ def HexagonAsmParserVariant : AsmParserVariant {
 def Hexagon : Target {
   // Pull in Instruction Info:
   let InstructionSet = HexagonInstrInfo;
+  let AssemblyParsers = [HexagonAsmParser];
   let AssemblyParserVariants = [HexagonAsmParserVariant];
 }

utils/TableGen/AsmMatcherEmitter.cpp

@@ -493,7 +493,8 @@ struct MatchableInfo {
 
   void initialize(const AsmMatcherInfo &Info,
                   SmallPtrSetImpl<Record*> &SingletonRegisters,
-                  AsmVariantInfo const &Variant);
+                  AsmVariantInfo const &Variant,
+                  bool HasMnemonicFirst);
 
   /// validate - Return true if this matchable is a valid thing to match against
   /// and perform a bunch of validity checking.
@@ -836,14 +837,33 @@ extractSingletonRegisterForAsmOperand(MatchableInfo::AsmOperand &Op,
 
 void MatchableInfo::initialize(const AsmMatcherInfo &Info,
                                SmallPtrSetImpl<Record*> &SingletonRegisters,
-                               AsmVariantInfo const &Variant) {
+                               AsmVariantInfo const &Variant,
+                               bool HasMnemonicFirst) {
   AsmVariantID = Variant.AsmVariantNo;
   AsmString =
     CodeGenInstruction::FlattenAsmStringVariants(AsmString,
                                                  Variant.AsmVariantNo);
 
   tokenizeAsmString(Info, Variant);
 
+  // The first token of the instruction is the mnemonic, which must be a
+  // simple string, not a $foo variable or a singleton register.
+  if (AsmOperands.empty())
+    PrintFatalError(TheDef->getLoc(),
+                  "Instruction '" + TheDef->getName() + "' has no tokens");
+
+  assert(!AsmOperands[0].Token.empty());
+  if (HasMnemonicFirst) {
+    Mnemonic = AsmOperands[0].Token;
+    if (Mnemonic[0] == '$')
+      PrintFatalError(TheDef->getLoc(),
+                      "Invalid instruction mnemonic '" + Mnemonic + "'!");
+
+    // Remove the first operand, it is tracked in the mnemonic field.
+    AsmOperands.erase(AsmOperands.begin());
+  } else if (AsmOperands[0].Token[0] != '$')
+    Mnemonic = AsmOperands[0].Token;
+
   // Compute the require features.
   for (Record *Predicate : TheDef->getValueAsListOfDefs("Predicates"))
     if (const SubtargetFeatureInfo *Feature =
@@ -953,15 +973,6 @@ void MatchableInfo::tokenizeAsmString(const AsmMatcherInfo &Info,
   }
   if (InTok && Prev != String.size())
     addAsmOperand(String.substr(Prev), IsIsolatedToken);
-
-  // The first token of the instruction is the mnemonic, which must be a
-  // simple string, not a $foo variable or a singleton register.
-  if (AsmOperands.empty())
-    PrintFatalError(TheDef->getLoc(),
-                  "Instruction '" + TheDef->getName() + "' has no tokens");
-  assert(!AsmOperands[0].Token.empty());
-  if (AsmOperands[0].Token[0] != '$')
-    Mnemonic = AsmOperands[0].Token;
 }
 
 bool MatchableInfo::validate(StringRef CommentDelimiter, bool Hack) const {
@@ -1369,6 +1380,8 @@ void AsmMatcherInfo::buildInfo() {
     assert(SubtargetFeatures.size() <= 64 && "Too many subtarget features!");
   }
 
+  bool HasMnemonicFirst = AsmParser->getValueAsBit("HasMnemonicFirst");
+
   // Parse the instructions; we need to do this first so that we can gather the
   // singleton register classes.
   SmallPtrSet<Record*, 16> SingletonRegisters;
@@ -1400,7 +1413,7 @@ void AsmMatcherInfo::buildInfo() {
 
       auto II = llvm::make_unique<MatchableInfo>(*CGI);
 
-      II->initialize(*this, SingletonRegisters, Variant);
+      II->initialize(*this, SingletonRegisters, Variant, HasMnemonicFirst);
 
       // Ignore instructions which shouldn't be matched and diagnose invalid
       // instruction definitions with an error.
@@ -1428,7 +1441,7 @@ void AsmMatcherInfo::buildInfo() {
 
       auto II = llvm::make_unique<MatchableInfo>(std::move(Alias));
 
-      II->initialize(*this, SingletonRegisters, Variant);
+      II->initialize(*this, SingletonRegisters, Variant, HasMnemonicFirst);
 
       // Validate the alias definitions.
       II->validate(CommentDelimiter, false);
@@ -1734,7 +1747,7 @@ static unsigned getConverterOperandID(const std::string &Name,
 
 static void emitConvertFuncs(CodeGenTarget &Target, StringRef ClassName,
                              std::vector<std::unique_ptr<MatchableInfo>> &Infos,
-                             raw_ostream &OS) {
+                             bool HasMnemonicFirst, raw_ostream &OS) {
   SmallSetVector<std::string, 16> OperandConversionKinds;
   SmallSetVector<std::string, 16> InstructionConversionKinds;
   std::vector<std::vector<uint8_t> > ConversionTable;
@@ -1868,7 +1881,7 @@ static void emitConvertFuncs(CodeGenTarget &Target, StringRef ClassName,
 
         // Add the operand entry to the instruction kind conversion row.
         ConversionRow.push_back(ID);
-        ConversionRow.push_back(OpInfo.AsmOperandNum);
+        ConversionRow.push_back(OpInfo.AsmOperandNum + HasMnemonicFirst);
 
         if (!IsNewConverter)
           break;
@@ -2472,7 +2485,7 @@ static bool emitMnemonicAliases(raw_ostream &OS, const AsmMatcherInfo &Info,
 static void emitCustomOperandParsing(raw_ostream &OS, CodeGenTarget &Target,
                               const AsmMatcherInfo &Info, StringRef ClassName,
                               StringToOffsetTable &StringTable,
-                              unsigned MaxMnemonicIndex) {
+                              unsigned MaxMnemonicIndex, bool HasMnemonicFirst) {
   unsigned MaxMask = 0;
   for (const OperandMatchEntry &OMI : Info.OperandMatchInfo) {
     MaxMask |= OMI.OperandMask;
@@ -2586,19 +2599,25 @@ static void emitCustomOperandParsing(raw_ostream &OS, CodeGenTarget &Target,
   OS << "  uint64_t AvailableFeatures = getAvailableFeatures();\n\n";
 
   OS << "  // Get the next operand index.\n";
-  OS << "  unsigned NextOpNum = Operands.size();\n";
+  OS << "  unsigned NextOpNum = Operands.size()"
+     << (HasMnemonicFirst ? " - 1" : "") << ";\n";
 
   // Emit code to search the table.
   OS << "  // Search the table.\n";
-  OS << "  std::pair<const OperandMatchEntry*, const OperandMatchEntry*>";
-  OS << " MnemonicRange\n";
-  OS << "       (OperandMatchTable, OperandMatchTable+";
-  OS << Info.OperandMatchInfo.size() << ");\n";
-  OS << "  if(!Mnemonic.empty())\n";
-  OS << "    MnemonicRange = std::equal_range(OperandMatchTable,";
-  OS << " OperandMatchTable+"
-     << Info.OperandMatchInfo.size() << ", Mnemonic,\n"
-     << "                     LessOpcodeOperand());\n\n";
+  if (HasMnemonicFirst) {
+    OS << "  auto MnemonicRange =\n";
+    OS << "    std::equal_range(std::begin(OperandMatchTable), "
+          "std::end(OperandMatchTable),\n";
+    OS << "                     Mnemonic, LessOpcodeOperand());\n\n";
+  } else {
+    OS << "  auto MnemonicRange = std::make_pair(std::begin(OperandMatchTable),"
+          " std::end(OperandMatchTable));\n";
+    OS << "  if (!Mnemonic.empty())\n";
+    OS << "    MnemonicRange =\n";
+    OS << "      std::equal_range(std::begin(OperandMatchTable), "
+          "std::end(OperandMatchTable),\n";
+    OS << "                       Mnemonic, LessOpcodeOperand());\n\n";
+  }
 
   OS << "  if (MnemonicRange.first == MnemonicRange.second)\n";
   OS << "    return MatchOperand_NoMatch;\n\n";
@@ -2683,6 +2702,8 @@ void AsmMatcherEmitter::run(raw_ostream &OS) {
   // Compute the information on the custom operand parsing.
   Info.buildOperandMatchInfo();
 
+  bool HasMnemonicFirst = AsmParser->getValueAsBit("HasMnemonicFirst");
+
   // Write the output.
 
   // Information for the class declaration.
@@ -2697,7 +2718,8 @@ void AsmMatcherEmitter::run(raw_ostream &OS) {
      << "&Operands);\n";
   OS << "  void convertToMapAndConstraints(unsigned Kind,\n                ";
   OS << "           const OperandVector &Operands) override;\n";
-  OS << "  bool mnemonicIsValid(StringRef Mnemonic, unsigned VariantID);\n";
+  if (HasMnemonicFirst)
+    OS << "  bool mnemonicIsValid(StringRef Mnemonic, unsigned VariantID);\n";
   OS << "  unsigned MatchInstructionImpl(const OperandVector &Operands,\n"
      << "                                MCInst &Inst,\n"
      << "                                uint64_t &ErrorInfo,"
@@ -2758,7 +2780,7 @@ void AsmMatcherEmitter::run(raw_ostream &OS) {
   // Generate the convertToMCInst function to convert operands into an MCInst.
   // Also, generate the convertToMapAndConstraints function for MS-style inline
   // assembly.  The latter doesn't actually generate a MCInst.
-  emitConvertFuncs(Target, ClassName, Info.Matchables, OS);
+  emitConvertFuncs(Target, ClassName, Info.Matchables, HasMnemonicFirst, OS);
 
   // Emit the enumeration for classes which participate in matching.
   emitMatchClassEnumeration(Target, Info.Classes, OS);
@@ -2880,24 +2902,26 @@ void AsmMatcherEmitter::run(raw_ostream &OS) {
   }
 
   // A method to determine if a mnemonic is in the list.
-  OS << "bool " << Target.getName() << ClassName << "::\n"
-     << "mnemonicIsValid(StringRef Mnemonic, unsigned VariantID) {\n";
-  OS << "  // Find the appropriate table for this asm variant.\n";
-  OS << "  const MatchEntry *Start, *End;\n";
-  OS << "  switch (VariantID) {\n";
-  OS << "  default: llvm_unreachable(\"invalid variant!\");\n";
-  for (unsigned VC = 0; VC != VariantCount; ++VC) {
-    Record *AsmVariant = Target.getAsmParserVariant(VC);
-    int AsmVariantNo = AsmVariant->getValueAsInt("Variant");
-    OS << "  case " << AsmVariantNo << ": Start = std::begin(MatchTable" << VC
-       << "); End = std::end(MatchTable" << VC << "); break;\n";
+  if (HasMnemonicFirst) {
+    OS << "bool " << Target.getName() << ClassName << "::\n"
+       << "mnemonicIsValid(StringRef Mnemonic, unsigned VariantID) {\n";
+    OS << "  // Find the appropriate table for this asm variant.\n";
+    OS << "  const MatchEntry *Start, *End;\n";
+    OS << "  switch (VariantID) {\n";
+    OS << "  default: llvm_unreachable(\"invalid variant!\");\n";
+    for (unsigned VC = 0; VC != VariantCount; ++VC) {
+      Record *AsmVariant = Target.getAsmParserVariant(VC);
+      int AsmVariantNo = AsmVariant->getValueAsInt("Variant");
+      OS << "  case " << AsmVariantNo << ": Start = std::begin(MatchTable" << VC
+         << "); End = std::end(MatchTable" << VC << "); break;\n";
+    }
+    OS << "  }\n";
+    OS << "  // Search the table.\n";
+    OS << "  auto MnemonicRange = ";
+    OS << "std::equal_range(Start, End, Mnemonic, LessOpcode());\n";
+    OS << "  return MnemonicRange.first != MnemonicRange.second;\n";
+    OS << "}\n\n";
   }
-  OS << "  }\n";
-  OS << "  // Search the table.\n";
-  OS << "  std::pair<const MatchEntry*, const MatchEntry*> MnemonicRange =\n";
-  OS << "    std::equal_range(Start, End, Mnemonic, LessOpcode());\n";
-  OS << "  return MnemonicRange.first != MnemonicRange.second;\n";
-  OS << "}\n\n";
 
   // Finally, build the match function.
   OS << "unsigned " << Target.getName() << ClassName << "::\n"
@@ -2906,8 +2930,10 @@ void AsmMatcherEmitter::run(raw_ostream &OS) {
      << "                     bool matchingInlineAsm, unsigned VariantID) {\n";
 
   OS << "  // Eliminate obvious mismatches.\n";
-  OS << "  if (Operands.size() > " << MaxNumOperands << ") {\n";
-  OS << "    ErrorInfo = " << MaxNumOperands << ";\n";
+  OS << "  if (Operands.size() > "
+     << (MaxNumOperands + HasMnemonicFirst) << ") {\n";
+  OS << "    ErrorInfo = "
+     << (MaxNumOperands + HasMnemonicFirst) << ";\n";
   OS << "    return Match_InvalidOperand;\n";
   OS << "  }\n\n";
 
@@ -2916,10 +2942,15 @@ void AsmMatcherEmitter::run(raw_ostream &OS) {
   OS << "  uint64_t AvailableFeatures = getAvailableFeatures();\n\n";
 
   OS << "  // Get the instruction mnemonic, which is the first token.\n";
-  OS << "  StringRef Mnemonic;\n";
-  OS << "  if (Operands[0]->isToken())\n";
-  OS << "    Mnemonic = ((" << Target.getName()
-     << "Operand&)*Operands[0]).getToken();\n\n";
+  if (HasMnemonicFirst) {
+    OS << "  StringRef Mnemonic = ((" << Target.getName()
+       << "Operand&)*Operands[0]).getToken();\n\n";
+  } else {
+    OS << "  StringRef Mnemonic;\n";
+    OS << "  if (Operands[0]->isToken())\n";
+    OS << "    Mnemonic = ((" << Target.getName()
+       << "Operand&)*Operands[0]).getToken();\n\n";
+  }
 
   if (HasMnemonicAliases) {
     OS << "  // Process all MnemonicAliases to remap the mnemonic.\n";
@@ -2948,12 +2979,18 @@ void AsmMatcherEmitter::run(raw_ostream &OS) {
        << "); End = std::end(MatchTable" << VC << "); break;\n";
   }
   OS << "  }\n";
+
   OS << "  // Search the table.\n";
-  OS << "  std::pair<const MatchEntry*, const MatchEntry*> "
-        "MnemonicRange(Start, End);\n";
-  OS << "  unsigned SIndex = Mnemonic.empty() ? 0 : 1;\n";
-  OS << "  if (!Mnemonic.empty())\n";
-  OS << "    MnemonicRange = std::equal_range(Start, End, Mnemonic.lower(), LessOpcode());\n\n";
+  if (HasMnemonicFirst) {
+    OS << "  auto MnemonicRange = "
+          "std::equal_range(Start, End, Mnemonic, LessOpcode());\n\n";
+  } else {
+    OS << "  auto MnemonicRange = std::make_pair(Start, End);\n";
+    OS << "  unsigned SIndex = Mnemonic.empty() ? 0 : 1;\n";
+    OS << "  if (!Mnemonic.empty())\n";
+    OS << "    MnemonicRange = "
+          "std::equal_range(Start, End, Mnemonic.lower(), LessOpcode());\n\n";
+  }
 
   OS << "  // Return a more specific error code if no mnemonics match.\n";
   OS << "  if (MnemonicRange.first == MnemonicRange.second)\n";
@@ -2963,16 +3000,25 @@ void AsmMatcherEmitter::run(raw_ostream &OS) {
      << "*ie = MnemonicRange.second;\n";
   OS << "       it != ie; ++it) {\n";
 
+  if (HasMnemonicFirst) {
+    OS << "    // equal_range guarantees that instruction mnemonic matches.\n";
+    OS << "    assert(Mnemonic == it->getMnemonic());\n";
+  }
+
   // Emit check that the subclasses match.
   OS << "    bool OperandsValid = true;\n";
-  OS << "    for (unsigned i = SIndex; i != " << MaxNumOperands << "; ++i) {\n";
+  OS << "    for (unsigned i = " << (HasMnemonicFirst ? "0" : "SIndex")
+     << "; i != " << MaxNumOperands << "; ++i) {\n";
   OS << "      auto Formal = static_cast<MatchClassKind>(it->Classes[i]);\n";
-  OS << "      if (i >= Operands.size()) {\n";
+  OS << "      if (i" << (HasMnemonicFirst ? "+1" : "")
+     << " >= Operands.size()) {\n";
   OS << "        OperandsValid = (Formal == " <<"InvalidMatchClass);\n";
-  OS << "        if (!OperandsValid) ErrorInfo = i;\n";
+  OS << "        if (!OperandsValid) ErrorInfo = i"
+     << (HasMnemonicFirst ? "+1" : "") << ";\n";
   OS << "        break;\n";
   OS << "      }\n";
-  OS << "      MCParsedAsmOperand &Actual = *Operands[i];\n";
+  OS << "      MCParsedAsmOperand &Actual = *Operands[i"
+     << (HasMnemonicFirst ? "+1" : "") << "];\n";
   OS << "      unsigned Diag = validateOperandClass(Actual, Formal);\n";
   OS << "      if (Diag == Match_Success)\n";
   OS << "        continue;\n";
@@ -2988,8 +3034,9 @@ void AsmMatcherEmitter::run(raw_ostream &OS) {
   OS << "      // If we already had a match that only failed due to a\n";
   OS << "      // target predicate, that diagnostic is preferred.\n";
   OS << "      if (!HadMatchOtherThanPredicate &&\n";
-  OS << "          (it == MnemonicRange.first || ErrorInfo <= i)) {\n";
-  OS << "        ErrorInfo = i;\n";
+  OS << "          (it == MnemonicRange.first || ErrorInfo <= i"
+     << (HasMnemonicFirst ? "+1" : "") << ")) {\n";
+  OS << "        ErrorInfo = i" << (HasMnemonicFirst ? "+1" : "") << ";\n";
   OS << "        // InvalidOperand is the default. Prefer specificity.\n";
   OS << "        if (Diag != Match_InvalidOperand)\n";
   OS << "          RetCode = Diag;\n";
@@ -3064,7 +3111,7 @@ void AsmMatcherEmitter::run(raw_ostream &OS) {
 
   if (!Info.OperandMatchInfo.empty())
     emitCustomOperandParsing(OS, Target, Info, ClassName, StringTable,
-                             MaxMnemonicIndex);
+                             MaxMnemonicIndex, HasMnemonicFirst);
 
   OS << "#endif // GET_MATCHER_IMPLEMENTATION\n\n";
 }