tools/mlir-tblgen/BytecodeDialectGen.cpp - llvm-project/mlir - Git at Google

 //===- BytecodeDialectGen.cpp - Dialect bytecode read/writer gen  ---------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//

 #include "mlir/Support/IndentedOstream.h"
 #include "mlir/TableGen/GenInfo.h"
 #include "llvm/ADT/MapVector.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/FormatVariadic.h"
 #include "llvm/TableGen/Error.h"
 #include "llvm/TableGen/Record.h"
 #include <regex>

 using namespace llvm;

 static llvm::cl::OptionCategory dialectGenCat("Options for -gen-bytecode");
 static llvm::cl::opt<std::string>
     selectedBcDialect("bytecode-dialect",
                       llvm::cl::desc("The dialect to gen for"),
                       llvm::cl::cat(dialectGenCat), llvm::cl::CommaSeparated);

 namespace {

 /// Helper class to generate C++ bytecode parser helpers.
 class Generator {
 public:
   Generator(raw_ostream &output) : output(output) {}

   /// Returns whether successfully emitted attribute/type parsers.
   void emitParse(StringRef kind, Record &x);

   /// Returns whether successfully emitted attribute/type printers.
   void emitPrint(StringRef kind, StringRef type,
                  ArrayRef<std::pair<int64_t, Record *>> vec);

   /// Emits parse dispatch table.
   void emitParseDispatch(StringRef kind, ArrayRef<Record *> vec);

   /// Emits print dispatch table.
   void emitPrintDispatch(StringRef kind, ArrayRef<std::string> vec);

 private:
   /// Emits parse calls to construct given kind.
   void emitParseHelper(StringRef kind, StringRef returnType, StringRef builder,
                        ArrayRef<Init *> args, ArrayRef<std::string> argNames,
                        StringRef failure, mlir::raw_indented_ostream &ios);

   /// Emits print instructions.
   void emitPrintHelper(Record *memberRec, StringRef kind, StringRef parent,
                        StringRef name, mlir::raw_indented_ostream &ios);

   raw_ostream &output;
 };
 } // namespace

 /// Helper to replace set of from strings to target in `s`.
 /// Assumed: non-overlapping replacements.
 static std::string format(StringRef templ,
                           std::map<std::string, std::string> &&map) {
   std::string s = templ.str();
   for (const auto &[from, to] : map)
     // All replacements start with $, don't treat as anchor.
     s = std::regex_replace(s, std::regex("\\" + from), to);
   return s;
 }

 /// Return string with first character capitalized.
 static std::string capitalize(StringRef str) {
   return ((Twine)toUpper(str[0]) + str.drop_front()).str();
 }

 /// Return the C++ type for the given record.
 static std::string getCType(Record *def) {
   std::string format = "{0}";
   if (def->isSubClassOf("Array")) {
     def = def->getValueAsDef("elemT");
     format = "SmallVector<{0}>";
   }

   StringRef cType = def->getValueAsString("cType");
   if (cType.empty()) {
     if (def->isAnonymous())
       PrintFatalError(def->getLoc(), "Unable to determine cType");

     return formatv(format.c_str(), def->getName().str());
   }
   return formatv(format.c_str(), cType.str());
 }

 void Generator::emitParseDispatch(StringRef kind, ArrayRef<Record *> vec) {
   mlir::raw_indented_ostream os(output);
   char const *head =
       R"(static {0} read{0}(MLIRContext* context, DialectBytecodeReader &reader))";
   os << formatv(head, capitalize(kind));
   auto funScope = os.scope(" {\n", "}\n\n");

   if (vec.empty()) {
     os << "return reader.emitError() << \"unknown attribute\", "
        << capitalize(kind) << "();\n";
     return;
   }

   os << "uint64_t kind;\n";
   os << "if (failed(reader.readVarInt(kind)))\n"
      << "  return " << capitalize(kind) << "();\n";
   os << "switch (kind) ";
   {
     auto switchScope = os.scope("{\n", "}\n");
     for (const auto &it : llvm::enumerate(vec)) {
       if (it.value()->getName() == "ReservedOrDead")
         continue;

       os << formatv("case {1}:\n  return read{0}(context, reader);\n",
                     it.value()->getName(), it.index());
     }
     os << "default:\n"
        << "  reader.emitError() << \"unknown attribute code: \" "
        << "<< kind;\n"
        << "  return " << capitalize(kind) << "();\n";
   }
   os << "return " << capitalize(kind) << "();\n";
 }

 void Generator::emitParse(StringRef kind, Record &x) {
   if (x.getNameInitAsString() == "ReservedOrDead")
     return;

   char const *head =
       R"(static {0} read{1}(MLIRContext* context, DialectBytecodeReader &reader) )";
   mlir::raw_indented_ostream os(output);
   std::string returnType = getCType(&x);
   os << formatv(head, kind == "attribute" ? "::mlir::Attribute" : "::mlir::Type", x.getName());
   DagInit *members = x.getValueAsDag("members");
   SmallVector<std::string> argNames =
       llvm::to_vector(map_range(members->getArgNames(), [](StringInit *init) {
         return init->getAsUnquotedString();
       }));
   StringRef builder = x.getValueAsString("cBuilder").trim();
   emitParseHelper(kind, returnType, builder, members->getArgs(), argNames,
                   returnType + "()", os);
   os << "\n\n";
 }

 void printParseConditional(mlir::raw_indented_ostream &ios,
                            ArrayRef<Init *> args,
                            ArrayRef<std::string> argNames) {
   ios << "if ";
   auto parenScope = ios.scope("(", ") {");
   ios.indent();

   auto listHelperName = [](StringRef name) {
     return formatv("read{0}", capitalize(name));
   };

   auto parsedArgs =
       llvm::to_vector(make_filter_range(args, [](Init *const attr) {
         Record *def = cast<DefInit>(attr)->getDef();
         if (def->isSubClassOf("Array"))
           return true;
         return !def->getValueAsString("cParser").empty();
       }));

   interleave(
       zip(parsedArgs, argNames),
       [&](std::tuple<llvm::Init *&, const std::string &> it) {
         Record *attr = cast<DefInit>(std::get<0>(it))->getDef();
         std::string parser;
         if (auto optParser = attr->getValueAsOptionalString("cParser")) {
           parser = *optParser;
         } else if (attr->isSubClassOf("Array")) {
           Record *def = attr->getValueAsDef("elemT");
           bool composite = def->isSubClassOf("CompositeBytecode");
           if (!composite && def->isSubClassOf("AttributeKind"))
             parser = "succeeded($_reader.readAttributes($_var))";
           else if (!composite && def->isSubClassOf("TypeKind"))
             parser = "succeeded($_reader.readTypes($_var))";
           else
             parser = ("succeeded($_reader.readList($_var, " +
                       listHelperName(std::get<1>(it)) + "))")
                          .str();
         } else {
           PrintFatalError(attr->getLoc(), "No parser specified");
         }
         std::string type = getCType(attr);
         ios << format(parser, {{"$_reader", "reader"},
                                {"$_resultType", type},
                                {"$_var", std::get<1>(it)}});
       },
       [&]() { ios << " &&\n"; });
 }

 void Generator::emitParseHelper(StringRef kind, StringRef returnType,
                                 StringRef builder, ArrayRef<Init *> args,
                                 ArrayRef<std::string> argNames,
                                 StringRef failure,
                                 mlir::raw_indented_ostream &ios) {
   auto funScope = ios.scope("{\n", "}");

   if (args.empty()) {
     ios << formatv("return get<{0}>(context);\n", returnType);
     return;
   }

   // Print decls.
   std::string lastCType = "";
   for (auto [arg, name] : zip(args, argNames)) {
     DefInit *first = dyn_cast<DefInit>(arg);
     if (!first)
       PrintFatalError("Unexpected type for " + name);
     Record *def = first->getDef();

     // Create variable decls, if there are a block of same type then create
     // comma separated list of them.
     std::string cType = getCType(def);
     if (lastCType == cType) {
       ios << ", ";
     } else {
       if (!lastCType.empty())
         ios << ";\n";
       ios << cType << " ";
     }
     ios << name;
     lastCType = cType;
   }
   ios << ";\n";

   // Returns the name of the helper used in list parsing. E.g., the name of the
   // lambda passed to array parsing.
   auto listHelperName = [](StringRef name) {
     return formatv("read{0}", capitalize(name));
   };

   // Emit list helper functions.
   for (auto [arg, name] : zip(args, argNames)) {
     Record *attr = cast<DefInit>(arg)->getDef();
     if (!attr->isSubClassOf("Array"))
       continue;

     // TODO: Dedupe readers.
     Record *def = attr->getValueAsDef("elemT");
     if (!def->isSubClassOf("CompositeBytecode") &&
         (def->isSubClassOf("AttributeKind") || def->isSubClassOf("TypeKind")))
       continue;

     std::string returnType = getCType(def);
     ios << "auto " << listHelperName(name) << " = [&]() -> FailureOr<"
         << returnType << "> ";
     SmallVector<Init *> args;
     SmallVector<std::string> argNames;
     if (def->isSubClassOf("CompositeBytecode")) {
       DagInit *members = def->getValueAsDag("members");
       args = llvm::to_vector(members->getArgs());
       argNames = llvm::to_vector(
           map_range(members->getArgNames(), [](StringInit *init) {
             return init->getAsUnquotedString();
           }));
     } else {
       args = {def->getDefInit()};
       argNames = {"temp"};
     }
     StringRef builder = def->getValueAsString("cBuilder");
     emitParseHelper(kind, returnType, builder, args, argNames, "failure()",
                     ios);
     ios << ";\n";
   }

   // Print parse conditional.
   printParseConditional(ios, args, argNames);

   // Compute args to pass to create method.
   auto passedArgs = llvm::to_vector(make_filter_range(
       argNames, [](StringRef str) { return !str.starts_with("_"); }));
   std::string argStr;
   raw_string_ostream argStream(argStr);
   interleaveComma(passedArgs, argStream,
                   [&](const std::string &str) { argStream << str; });
   // Return the invoked constructor.
   ios << "\nreturn "
       << format(builder, {{"$_resultType", returnType.str()},
                           {"$_args", argStream.str()}})
       << ";\n";
   ios.unindent();

   // TODO: Emit error in debug.
   // This assumes the result types in error case can always be empty
   // constructed.
   ios << "}\nreturn " << failure << ";\n";
 }

 void Generator::emitPrint(StringRef kind, StringRef type,
                           ArrayRef<std::pair<int64_t, Record *>> vec) {
   if (type == "ReservedOrDead")
     return;

   char const *head =
       R"(static void write({0} {1}, DialectBytecodeWriter &writer) )";
   mlir::raw_indented_ostream os(output);
   os << formatv(head, type, kind);
   auto funScope = os.scope("{\n", "}\n\n");

   // Check that predicates specified if multiple bytecode instances.
   for (llvm::Record *rec : make_second_range(vec)) {
     StringRef pred = rec->getValueAsString("printerPredicate");
     if (vec.size() > 1 && pred.empty()) {
       for (auto [index, rec] : vec) {
         (void)index;
         StringRef pred = rec->getValueAsString("printerPredicate");
         if (vec.size() > 1 && pred.empty())
           PrintError(rec->getLoc(),
                      "Requires parsing predicate given common cType");
       }
       PrintFatalError("Unspecified for shared cType " + type);
     }
   }

   for (auto [index, rec] : vec) {
     StringRef pred = rec->getValueAsString("printerPredicate");
     if (!pred.empty()) {
       os << "if (" << format(pred, {{"$_val", kind.str()}}) << ") {\n";
       os.indent();
     }

     os << "writer.writeVarInt(/* " << rec->getName() << " */ " << index
        << ");\n";

     auto *members = rec->getValueAsDag("members");
     for (auto [arg, name] :
          llvm::zip(members->getArgs(), members->getArgNames())) {
       DefInit *def = dyn_cast<DefInit>(arg);
       assert(def);
       Record *memberRec = def->getDef();
       emitPrintHelper(memberRec, kind, kind, name->getAsUnquotedString(), os);
     }

     if (!pred.empty()) {
       os.unindent();
       os << "}\n";
     }
   }
 }

 void Generator::emitPrintHelper(Record *memberRec, StringRef kind,
                                 StringRef parent, StringRef name,
                                 mlir::raw_indented_ostream &ios) {
   std::string getter;
   if (auto cGetter = memberRec->getValueAsOptionalString("cGetter");
       cGetter && !cGetter->empty()) {
     getter = format(
         *cGetter,
         {{"$_attrType", parent.str()},
          {"$_member", name.str()},
          {"$_getMember", "get" + convertToCamelFromSnakeCase(name, true)}});
   } else {
     getter =
         formatv("{0}.get{1}()", parent, convertToCamelFromSnakeCase(name, true))
             .str();
   }

   if (memberRec->isSubClassOf("Array")) {
     Record *def = memberRec->getValueAsDef("elemT");
     if (!def->isSubClassOf("CompositeBytecode")) {
       if (def->isSubClassOf("AttributeKind")) {
         ios << "writer.writeAttributes(" << getter << ");\n";
         return;
       }
       if (def->isSubClassOf("TypeKind")) {
         ios << "writer.writeTypes(" << getter << ");\n";
         return;
       }
     }
     std::string returnType = getCType(def);
     std::string nestedName = kind.str();
     ios << "writer.writeList(" << getter << ", [&](" << returnType << " "
         << nestedName << ") ";
     auto lambdaScope = ios.scope("{\n", "});\n");
     return emitPrintHelper(def, kind, nestedName, nestedName, ios);
   }
   if (memberRec->isSubClassOf("CompositeBytecode")) {
     auto *members = memberRec->getValueAsDag("members");
     for (auto [arg, argName] :
          zip(members->getArgs(), members->getArgNames())) {
       DefInit *def = dyn_cast<DefInit>(arg);
       assert(def);
       emitPrintHelper(def->getDef(), kind, parent,
                       argName->getAsUnquotedString(), ios);
     }
   }

   if (std::string printer = memberRec->getValueAsString("cPrinter").str();
       !printer.empty())
     ios << format(printer, {{"$_writer", "writer"},
                             {"$_name", kind.str()},
                             {"$_getter", getter}})
         << ";\n";
 }

 void Generator::emitPrintDispatch(StringRef kind, ArrayRef<std::string> vec) {
   mlir::raw_indented_ostream os(output);
   char const *head = R"(static LogicalResult write{0}({0} {1},
                                 DialectBytecodeWriter &writer))";
   os << formatv(head, capitalize(kind), kind);
   auto funScope = os.scope(" {\n", "}\n\n");

   os << "return TypeSwitch<" << capitalize(kind) << ", LogicalResult>(" << kind
      << ")";
   auto switchScope = os.scope("", "");
   for (StringRef type : vec) {
     if (type == "ReservedOrDead")
       continue;

     os << "\n.Case([&](" << type << " t)";
     auto caseScope = os.scope(" {\n", "})");
     os << "return write(t, writer), success();\n";
   }
   os << "\n.Default([&](" << capitalize(kind) << ") { return failure(); });\n";
 }

 namespace {
 /// Container of Attribute or Type for Dialect.
 struct AttrOrType {
   std::vector<Record *> attr, type;
 };
 } // namespace

 static bool emitBCRW(const RecordKeeper &records, raw_ostream &os) {
   MapVector<StringRef, AttrOrType> dialectAttrOrType;
   for (auto &it : records.getAllDerivedDefinitions("DialectAttributes")) {
     if (!selectedBcDialect.empty() &&
         it->getValueAsString("dialect") != selectedBcDialect)
       continue;
     dialectAttrOrType[it->getValueAsString("dialect")].attr =
         it->getValueAsListOfDefs("elems");
   }
   for (auto &it : records.getAllDerivedDefinitions("DialectTypes")) {
     if (!selectedBcDialect.empty() &&
         it->getValueAsString("dialect") != selectedBcDialect)
       continue;
     dialectAttrOrType[it->getValueAsString("dialect")].type =
         it->getValueAsListOfDefs("elems");
   }

   if (dialectAttrOrType.size() != 1)
     PrintFatalError("Single dialect per invocation required (either only "
                     "one in input file or specified via dialect option)");

   auto it = dialectAttrOrType.front();
   Generator gen(os);

   SmallVector<std::vector<Record *> *, 2> vecs;
   SmallVector<std::string, 2> kinds;
   vecs.push_back(&it.second.attr);
   kinds.push_back("attribute");
   vecs.push_back(&it.second.type);
   kinds.push_back("type");
   for (auto [vec, kind] : zip(vecs, kinds)) {
     // Handle Attribute/Type emission.
     std::map<std::string, std::vector<std::pair<int64_t, Record *>>> perType;
     for (auto kt : llvm::enumerate(*vec))
       perType[getCType(kt.value())].emplace_back(kt.index(), kt.value());
     for (const auto &jt : perType) {
       for (auto kt : jt.second)
         gen.emitParse(kind, *std::get<1>(kt));
       gen.emitPrint(kind, jt.first, jt.second);
     }
     gen.emitParseDispatch(kind, *vec);

     SmallVector<std::string> types;
     for (const auto &it : perType) {
       types.push_back(it.first);
     }
     gen.emitPrintDispatch(kind, types);
   }

   return false;
 }

 static mlir::GenRegistration
     genBCRW("gen-bytecode", "Generate dialect bytecode readers/writers",
             [](const RecordKeeper &records, raw_ostream &os) {
               return emitBCRW(records, os);
             });
	//===- BytecodeDialectGen.cpp - Dialect bytecode read/writer gen ---------===//
	//
	// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
	// See https://llvm.org/LICENSE.txt for license information.
	// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
	//
	//===----------------------------------------------------------------------===//

	#include "mlir/Support/IndentedOstream.h"
	#include "mlir/TableGen/GenInfo.h"
	#include "llvm/ADT/MapVector.h"
	#include "llvm/ADT/STLExtras.h"
	#include "llvm/Support/CommandLine.h"
	#include "llvm/Support/FormatVariadic.h"
	#include "llvm/TableGen/Error.h"
	#include "llvm/TableGen/Record.h"
	#include <regex>

	using namespace llvm;

	static llvm::cl::OptionCategory dialectGenCat("Options for -gen-bytecode");
	static llvm::cl::opt<std::string>
	selectedBcDialect("bytecode-dialect",
	llvm::cl::desc("The dialect to gen for"),
	llvm::cl::cat(dialectGenCat), llvm::cl::CommaSeparated);

	namespace {

	/// Helper class to generate C++ bytecode parser helpers.
	class Generator {
	public:
	Generator(raw_ostream &output) : output(output) {}

	/// Returns whether successfully emitted attribute/type parsers.
	void emitParse(StringRef kind, Record &x);

	/// Returns whether successfully emitted attribute/type printers.
	void emitPrint(StringRef kind, StringRef type,
	ArrayRef<std::pair<int64_t, Record *>> vec);

	/// Emits parse dispatch table.
	void emitParseDispatch(StringRef kind, ArrayRef<Record *> vec);

	/// Emits print dispatch table.
	void emitPrintDispatch(StringRef kind, ArrayRef<std::string> vec);

	private:
	/// Emits parse calls to construct given kind.
	void emitParseHelper(StringRef kind, StringRef returnType, StringRef builder,
	ArrayRef<Init *> args, ArrayRef<std::string> argNames,
	StringRef failure, mlir::raw_indented_ostream &ios);

	/// Emits print instructions.
	void emitPrintHelper(Record *memberRec, StringRef kind, StringRef parent,
	StringRef name, mlir::raw_indented_ostream &ios);

	raw_ostream &output;
	};
	} // namespace

	/// Helper to replace set of from strings to target in `s`.
	/// Assumed: non-overlapping replacements.
	static std::string format(StringRef templ,
	std::map<std::string, std::string> &&map) {
	std::string s = templ.str();
	for (const auto &[from, to] : map)
	// All replacements start with $, don't treat as anchor.
	s = std::regex_replace(s, std::regex("\\" + from), to);
	return s;
	}

	/// Return string with first character capitalized.
	static std::string capitalize(StringRef str) {
	return ((Twine)toUpper(str[0]) + str.drop_front()).str();
	}

	/// Return the C++ type for the given record.
	static std::string getCType(Record *def) {
	std::string format = "{0}";
	if (def->isSubClassOf("Array")) {
	def = def->getValueAsDef("elemT");
	format = "SmallVector<{0}>";
	}

	StringRef cType = def->getValueAsString("cType");
	if (cType.empty()) {
	if (def->isAnonymous())
	PrintFatalError(def->getLoc(), "Unable to determine cType");

	return formatv(format.c_str(), def->getName().str());
	}
	return formatv(format.c_str(), cType.str());
	}

	void Generator::emitParseDispatch(StringRef kind, ArrayRef<Record *> vec) {
	mlir::raw_indented_ostream os(output);
	char const *head =
	R"(static {0} read{0}(MLIRContext* context, DialectBytecodeReader &reader))";
	os << formatv(head, capitalize(kind));
	auto funScope = os.scope(" {\n", "}\n\n");

	if (vec.empty()) {
	os << "return reader.emitError() << \"unknown attribute\", "
	<< capitalize(kind) << "();\n";
	return;
	}

	os << "uint64_t kind;\n";
	os << "if (failed(reader.readVarInt(kind)))\n"
	<< " return " << capitalize(kind) << "();\n";
	os << "switch (kind) ";
	{
	auto switchScope = os.scope("{\n", "}\n");
	for (const auto &it : llvm::enumerate(vec)) {
	if (it.value()->getName() == "ReservedOrDead")
	continue;

	os << formatv("case {1}:\n return read{0}(context, reader);\n",
	it.value()->getName(), it.index());
	}
	os << "default:\n"
	<< " reader.emitError() << \"unknown attribute code: \" "
	<< "<< kind;\n"
	<< " return " << capitalize(kind) << "();\n";
	}
	os << "return " << capitalize(kind) << "();\n";
	}

	void Generator::emitParse(StringRef kind, Record &x) {
	if (x.getNameInitAsString() == "ReservedOrDead")
	return;

	char const *head =
	R"(static {0} read{1}(MLIRContext* context, DialectBytecodeReader &reader) )";
	mlir::raw_indented_ostream os(output);
	std::string returnType = getCType(&x);
	os << formatv(head, kind == "attribute" ? "::mlir::Attribute" : "::mlir::Type", x.getName());
	DagInit *members = x.getValueAsDag("members");
	SmallVector<std::string> argNames =
	llvm::to_vector(map_range(members->getArgNames(), [](StringInit *init) {
	return init->getAsUnquotedString();
	}));
	StringRef builder = x.getValueAsString("cBuilder").trim();
	emitParseHelper(kind, returnType, builder, members->getArgs(), argNames,
	returnType + "()", os);
	os << "\n\n";
	}

	void printParseConditional(mlir::raw_indented_ostream &ios,
	ArrayRef<Init *> args,
	ArrayRef<std::string> argNames) {
	ios << "if ";
	auto parenScope = ios.scope("(", ") {");
	ios.indent();

	auto listHelperName = [](StringRef name) {
	return formatv("read{0}", capitalize(name));
	};

	auto parsedArgs =
	llvm::to_vector(make_filter_range(args, [](Init *const attr) {
	Record *def = cast<DefInit>(attr)->getDef();
	if (def->isSubClassOf("Array"))
	return true;
	return !def->getValueAsString("cParser").empty();
	}));

	interleave(
	zip(parsedArgs, argNames),
	[&](std::tuple<llvm::Init *&, const std::string &> it) {
	Record *attr = cast<DefInit>(std::get<0>(it))->getDef();
	std::string parser;
	if (auto optParser = attr->getValueAsOptionalString("cParser")) {
	parser = *optParser;
	} else if (attr->isSubClassOf("Array")) {
	Record *def = attr->getValueAsDef("elemT");
	bool composite = def->isSubClassOf("CompositeBytecode");
	if (!composite && def->isSubClassOf("AttributeKind"))
	parser = "succeeded($_reader.readAttributes($_var))";
	else if (!composite && def->isSubClassOf("TypeKind"))
	parser = "succeeded($_reader.readTypes($_var))";
	else
	parser = ("succeeded($_reader.readList($_var, " +
	listHelperName(std::get<1>(it)) + "))")
	.str();
	} else {
	PrintFatalError(attr->getLoc(), "No parser specified");
	}
	std::string type = getCType(attr);
	ios << format(parser, {{"$_reader", "reader"},
	{"$_resultType", type},
	{"$_var", std::get<1>(it)}});
	},
	[&]() { ios << " &&\n"; });
	}

	void Generator::emitParseHelper(StringRef kind, StringRef returnType,
	StringRef builder, ArrayRef<Init *> args,
	ArrayRef<std::string> argNames,
	StringRef failure,
	mlir::raw_indented_ostream &ios) {
	auto funScope = ios.scope("{\n", "}");

	if (args.empty()) {
	ios << formatv("return get<{0}>(context);\n", returnType);
	return;
	}

	// Print decls.
	std::string lastCType = "";
	for (auto [arg, name] : zip(args, argNames)) {
	DefInit *first = dyn_cast<DefInit>(arg);
	if (!first)
	PrintFatalError("Unexpected type for " + name);
	Record *def = first->getDef();

	// Create variable decls, if there are a block of same type then create
	// comma separated list of them.
	std::string cType = getCType(def);
	if (lastCType == cType) {
	ios << ", ";
	} else {
	if (!lastCType.empty())
	ios << ";\n";
	ios << cType << " ";
	}
	ios << name;
	lastCType = cType;
	}
	ios << ";\n";

	// Returns the name of the helper used in list parsing. E.g., the name of the
	// lambda passed to array parsing.
	auto listHelperName = [](StringRef name) {
	return formatv("read{0}", capitalize(name));
	};

	// Emit list helper functions.
	for (auto [arg, name] : zip(args, argNames)) {
	Record *attr = cast<DefInit>(arg)->getDef();
	if (!attr->isSubClassOf("Array"))
	continue;

	// TODO: Dedupe readers.
	Record *def = attr->getValueAsDef("elemT");
	if (!def->isSubClassOf("CompositeBytecode") &&
	(def->isSubClassOf("AttributeKind") \|\| def->isSubClassOf("TypeKind")))
	continue;

	std::string returnType = getCType(def);
	ios << "auto " << listHelperName(name) << " = [&]() -> FailureOr<"
	<< returnType << "> ";
	SmallVector<Init *> args;
	SmallVector<std::string> argNames;
	if (def->isSubClassOf("CompositeBytecode")) {
	DagInit *members = def->getValueAsDag("members");
	args = llvm::to_vector(members->getArgs());
	argNames = llvm::to_vector(
	map_range(members->getArgNames(), [](StringInit *init) {
	return init->getAsUnquotedString();
	}));
	} else {
	args = {def->getDefInit()};
	argNames = {"temp"};
	}
	StringRef builder = def->getValueAsString("cBuilder");
	emitParseHelper(kind, returnType, builder, args, argNames, "failure()",
	ios);
	ios << ";\n";
	}

	// Print parse conditional.
	printParseConditional(ios, args, argNames);

	// Compute args to pass to create method.
	auto passedArgs = llvm::to_vector(make_filter_range(
	argNames, [](StringRef str) { return !str.starts_with("_"); }));
	std::string argStr;
	raw_string_ostream argStream(argStr);
	interleaveComma(passedArgs, argStream,
	[&](const std::string &str) { argStream << str; });
	// Return the invoked constructor.
	ios << "\nreturn "
	<< format(builder, {{"$_resultType", returnType.str()},
	{"$_args", argStream.str()}})
	<< ";\n";
	ios.unindent();

	// TODO: Emit error in debug.
	// This assumes the result types in error case can always be empty
	// constructed.
	ios << "}\nreturn " << failure << ";\n";
	}

	void Generator::emitPrint(StringRef kind, StringRef type,
	ArrayRef<std::pair<int64_t, Record *>> vec) {
	if (type == "ReservedOrDead")
	return;

	char const *head =
	R"(static void write({0} {1}, DialectBytecodeWriter &writer) )";
	mlir::raw_indented_ostream os(output);
	os << formatv(head, type, kind);
	auto funScope = os.scope("{\n", "}\n\n");

	// Check that predicates specified if multiple bytecode instances.
	for (llvm::Record *rec : make_second_range(vec)) {
	StringRef pred = rec->getValueAsString("printerPredicate");
	if (vec.size() > 1 && pred.empty()) {
	for (auto [index, rec] : vec) {
	(void)index;
	StringRef pred = rec->getValueAsString("printerPredicate");
	if (vec.size() > 1 && pred.empty())
	PrintError(rec->getLoc(),
	"Requires parsing predicate given common cType");
	}
	PrintFatalError("Unspecified for shared cType " + type);
	}
	}

	for (auto [index, rec] : vec) {
	StringRef pred = rec->getValueAsString("printerPredicate");
	if (!pred.empty()) {
	os << "if (" << format(pred, {{"$_val", kind.str()}}) << ") {\n";
	os.indent();
	}

	os << "writer.writeVarInt(/* " << rec->getName() << " */ " << index
	<< ");\n";

	auto *members = rec->getValueAsDag("members");
	for (auto [arg, name] :
	llvm::zip(members->getArgs(), members->getArgNames())) {
	DefInit *def = dyn_cast<DefInit>(arg);
	assert(def);
	Record *memberRec = def->getDef();
	emitPrintHelper(memberRec, kind, kind, name->getAsUnquotedString(), os);
	}

	if (!pred.empty()) {
	os.unindent();
	os << "}\n";
	}
	}
	}

	void Generator::emitPrintHelper(Record *memberRec, StringRef kind,
	StringRef parent, StringRef name,
	mlir::raw_indented_ostream &ios) {
	std::string getter;
	if (auto cGetter = memberRec->getValueAsOptionalString("cGetter");
	cGetter && !cGetter->empty()) {
	getter = format(
	*cGetter,
	{{"$_attrType", parent.str()},
	{"$_member", name.str()},
	{"$_getMember", "get" + convertToCamelFromSnakeCase(name, true)}});
	} else {
	getter =
	formatv("{0}.get{1}()", parent, convertToCamelFromSnakeCase(name, true))
	.str();
	}

	if (memberRec->isSubClassOf("Array")) {
	Record *def = memberRec->getValueAsDef("elemT");
	if (!def->isSubClassOf("CompositeBytecode")) {
	if (def->isSubClassOf("AttributeKind")) {
	ios << "writer.writeAttributes(" << getter << ");\n";
	return;
	}
	if (def->isSubClassOf("TypeKind")) {
	ios << "writer.writeTypes(" << getter << ");\n";
	return;
	}
	}
	std::string returnType = getCType(def);
	std::string nestedName = kind.str();
	ios << "writer.writeList(" << getter << ", [&](" << returnType << " "
	<< nestedName << ") ";
	auto lambdaScope = ios.scope("{\n", "});\n");
	return emitPrintHelper(def, kind, nestedName, nestedName, ios);
	}
	if (memberRec->isSubClassOf("CompositeBytecode")) {
	auto *members = memberRec->getValueAsDag("members");
	for (auto [arg, argName] :
	zip(members->getArgs(), members->getArgNames())) {
	DefInit *def = dyn_cast<DefInit>(arg);
	assert(def);
	emitPrintHelper(def->getDef(), kind, parent,
	argName->getAsUnquotedString(), ios);
	}
	}

	if (std::string printer = memberRec->getValueAsString("cPrinter").str();
	!printer.empty())
	ios << format(printer, {{"$_writer", "writer"},
	{"$_name", kind.str()},
	{"$_getter", getter}})
	<< ";\n";
	}

	void Generator::emitPrintDispatch(StringRef kind, ArrayRef<std::string> vec) {
	mlir::raw_indented_ostream os(output);
	char const *head = R"(static LogicalResult write{0}({0} {1},
	DialectBytecodeWriter &writer))";
	os << formatv(head, capitalize(kind), kind);
	auto funScope = os.scope(" {\n", "}\n\n");

	os << "return TypeSwitch<" << capitalize(kind) << ", LogicalResult>(" << kind
	<< ")";
	auto switchScope = os.scope("", "");
	for (StringRef type : vec) {
	if (type == "ReservedOrDead")
	continue;

	os << "\n.Case([&](" << type << " t)";
	auto caseScope = os.scope(" {\n", "})");
	os << "return write(t, writer), success();\n";
	}
	os << "\n.Default([&](" << capitalize(kind) << ") { return failure(); });\n";
	}

	namespace {
	/// Container of Attribute or Type for Dialect.
	struct AttrOrType {
	std::vector<Record *> attr, type;
	};
	} // namespace

	static bool emitBCRW(const RecordKeeper &records, raw_ostream &os) {
	MapVector<StringRef, AttrOrType> dialectAttrOrType;
	for (auto &it : records.getAllDerivedDefinitions("DialectAttributes")) {
	if (!selectedBcDialect.empty() &&
	it->getValueAsString("dialect") != selectedBcDialect)
	continue;
	dialectAttrOrType[it->getValueAsString("dialect")].attr =
	it->getValueAsListOfDefs("elems");
	}
	for (auto &it : records.getAllDerivedDefinitions("DialectTypes")) {
	if (!selectedBcDialect.empty() &&
	it->getValueAsString("dialect") != selectedBcDialect)
	continue;
	dialectAttrOrType[it->getValueAsString("dialect")].type =
	it->getValueAsListOfDefs("elems");
	}

	if (dialectAttrOrType.size() != 1)
	PrintFatalError("Single dialect per invocation required (either only "
	"one in input file or specified via dialect option)");

	auto it = dialectAttrOrType.front();
	Generator gen(os);

	SmallVector<std::vector<Record > , 2> vecs;
	SmallVector<std::string, 2> kinds;
	vecs.push_back(&it.second.attr);
	kinds.push_back("attribute");
	vecs.push_back(&it.second.type);
	kinds.push_back("type");
	for (auto [vec, kind] : zip(vecs, kinds)) {
	// Handle Attribute/Type emission.
	std::map<std::string, std::vector<std::pair<int64_t, Record *>>> perType;
	for (auto kt : llvm::enumerate(*vec))
	perType[getCType(kt.value())].emplace_back(kt.index(), kt.value());
	for (const auto &jt : perType) {
	for (auto kt : jt.second)
	gen.emitParse(kind, *std::get<1>(kt));
	gen.emitPrint(kind, jt.first, jt.second);
	}
	gen.emitParseDispatch(kind, *vec);

	SmallVector<std::string> types;
	for (const auto &it : perType) {
	types.push_back(it.first);
	}
	gen.emitPrintDispatch(kind, types);
	}

	return false;
	}

	static mlir::GenRegistration
	genBCRW("gen-bytecode", "Generate dialect bytecode readers/writers",
	[](const RecordKeeper &records, raw_ostream &os) {
	return emitBCRW(records, os);
	});