mlir/tools/mlir-tblgen/AttrOrTypeFormatGen.cpp

   1 //===- AttrOrTypeFormatGen.cpp - MLIR attribute and type format generator -===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "AttrOrTypeFormatGen.h"
  10 #include "FormatGen.h"
  11 #include "mlir/Support/LLVM.h"
  12 #include "mlir/TableGen/AttrOrTypeDef.h"
  13 #include "mlir/TableGen/Format.h"
  14 #include "mlir/TableGen/GenInfo.h"
  15 #include "llvm/ADT/BitVector.h"
  16 #include "llvm/ADT/StringExtras.h"
  17 #include "llvm/ADT/StringSwitch.h"
  18 #include "llvm/ADT/TypeSwitch.h"
  19 #include "llvm/Support/MemoryBuffer.h"
  20 #include "llvm/Support/SaveAndRestore.h"
  21 #include "llvm/Support/SourceMgr.h"
  22 #include "llvm/TableGen/Error.h"
  23 #include "llvm/TableGen/TableGenBackend.h"
  24
  25 using namespace mlir;
  26 using namespace mlir::tblgen;
  27
  28 using llvm::formatv;
  29
  30 //===----------------------------------------------------------------------===//
  31 // Element
  32 //===----------------------------------------------------------------------===//
  33
  34 namespace {
  35 /// This class represents an instance of a variable element. A variable refers
  36 /// to an attribute or type parameter.
  37 class ParameterElement
  38     : public VariableElementBase<VariableElement::Parameter> {
  39 public:
  40   ParameterElement(AttrOrTypeParameter param) : param(param) {}
  41
  42   /// Get the parameter in the element.
  43   const AttrOrTypeParameter &getParam() const { return param; }
  44
  45   /// Indicate if this variable is printed "qualified" (that is it is
  46   /// prefixed with the `#dialect.mnemonic`).
  47   bool shouldBeQualified() { return shouldBeQualifiedFlag; }
  48   void setShouldBeQualified(bool qualified = true) {
  49     shouldBeQualifiedFlag = qualified;
  50   }
  51
  52   /// Returns true if the element contains an optional parameter.
  53   bool isOptional() const { return param.isOptional(); }
  54
  55   /// Returns the name of the parameter.
  56   StringRef getName() const { return param.getName(); }
  57
  58   /// Return the code to check whether the parameter is present.
  59   auto genIsPresent(FmtContext &ctx, const Twine &self) const {
  60     assert(isOptional() && "cannot guard on a mandatory parameter");
  61     std::string valueStr = tgfmt(*param.getDefaultValue(), &ctx).str();
  62     ctx.addSubst("_lhs", self).addSubst("_rhs", valueStr);
  63     return tgfmt(getParam().getComparator(), &ctx);
  64   }
  65
  66   /// Generate the code to check whether the parameter should be printed.
  67   MethodBody &genPrintGuard(FmtContext &ctx, MethodBody &os) const {
  68     assert(isOptional() && "cannot guard on a mandatory parameter");
  69     std::string self = param.getAccessorName() + "()";
  70     return os << "!(" << genIsPresent(ctx, self) << ")";
  71   }
  72
  73 private:
  74   bool shouldBeQualifiedFlag = false;
  75   AttrOrTypeParameter param;
  76 };
  77
  78 /// Shorthand functions that can be used with ranged-based conditions.
  79 static bool paramIsOptional(ParameterElement *el) { return el->isOptional(); }
  80 static bool paramNotOptional(ParameterElement *el) { return !el->isOptional(); }
  81
  82 /// Base class for a directive that contains references to multiple variables.
  83 template <DirectiveElement::Kind DirectiveKind>
  84 class ParamsDirectiveBase : public DirectiveElementBase<DirectiveKind> {
  85 public:
  86   using Base = ParamsDirectiveBase<DirectiveKind>;
  87
  88   ParamsDirectiveBase(std::vector<ParameterElement *> &&params)
  89       : params(std::move(params)) {}
  90
  91   /// Get the parameters contained in this directive.
  92   ArrayRef<ParameterElement *> getParams() const { return params; }
  93
  94   /// Get the number of parameters.
  95   unsigned getNumParams() const { return params.size(); }
  96
  97   /// Take all of the parameters from this directive.
  98   std::vector<ParameterElement *> takeParams() { return std::move(params); }
  99
 100   /// Returns true if there are optional parameters present.
 101   bool hasOptionalParams() const {
 102     return llvm::any_of(getParams(), paramIsOptional);
 103   }
 104
 105 private:
 106   /// The parameters captured by this directive.
 107   std::vector<ParameterElement *> params;
 108 };
 109
 110 /// This class represents a `params` directive that refers to all parameters
 111 /// of an attribute or type. When used as a top-level directive, it generates
 112 /// a format of the form:
 113 ///
 114 ///   (param-value (`,` param-value)*)?
 115 ///
 116 /// When used as an argument to another directive that accepts variables,
 117 /// `params` can be used in place of manually listing all parameters of an
 118 /// attribute or type.
 119 class ParamsDirective : public ParamsDirectiveBase<DirectiveElement::Params> {
 120 public:
 121   using Base::Base;
 122 };
 123
 124 /// This class represents a `struct` directive that generates a struct format
 125 /// of the form:
 126 ///
 127 ///   `{` param-name `=` param-value (`,` param-name `=` param-value)* `}`
 128 ///
 129 class StructDirective : public ParamsDirectiveBase<DirectiveElement::Struct> {
 130 public:
 131   using Base::Base;
 132 };
 133
 134 } // namespace
 135
 136 //===----------------------------------------------------------------------===//
 137 // Format Strings
 138 //===----------------------------------------------------------------------===//
 139
 140 /// Default parser for attribute or type parameters.
 141 static const char *const defaultParameterParser =
 142     "::mlir::FieldParser<$0>::parse($_parser)";
 143
 144 /// Default printer for attribute or type parameters.
 145 static const char *const defaultParameterPrinter =
 146     "$_printer.printStrippedAttrOrType($_self)";
 147
 148 /// Qualified printer for attribute or type parameters: it does not elide
 149 /// dialect and mnemonic.
 150 static const char *const qualifiedParameterPrinter = "$_printer << $_self";
 151
 152 /// Print an error when failing to parse an element.
 153 ///
 154 /// $0: The parameter C++ class name.
 155 static const char *const parserErrorStr =
 156     "$_parser.emitError($_parser.getCurrentLocation(), ";
 157
 158 /// Code format to parse a variable. Separate by lines because variable parsers
 159 /// may be generated inside other directives, which requires indentation.
 160 ///
 161 /// {0}: The parameter name.
 162 /// {1}: The parse code for the parameter.
 163 /// {2}: Code template for printing an error.
 164 /// {3}: Name of the attribute or type.
 165 /// {4}: C++ class of the parameter.
 166 /// {5}: Optional code to preload the dialect for this variable.
 167 static const char *const variableParser = R"(
 168 // Parse variable '{0}'{5}
 169 _result_{0} = {1};
 170 if (::mlir::failed(_result_{0})) {{
 171   {2}"failed to parse {3} parameter '{0}' which is to be a `{4}`");
 172   return {{};
 173 }
 174 )";
 175
 176 //===----------------------------------------------------------------------===//
 177 // DefFormat
 178 //===----------------------------------------------------------------------===//
 179
 180 namespace {
 181 class DefFormat {
 182 public:
 183   DefFormat(const AttrOrTypeDef &def, std::vector<FormatElement *> &&elements)
 184       : def(def), elements(std::move(elements)) {}
 185
 186   /// Generate the attribute or type parser.
 187   void genParser(MethodBody &os);
 188   /// Generate the attribute or type printer.
 189   void genPrinter(MethodBody &os);
 190
 191 private:
 192   /// Generate the parser code for a specific format element.
 193   void genElementParser(FormatElement *el, FmtContext &ctx, MethodBody &os);
 194   /// Generate the parser code for a literal.
 195   void genLiteralParser(StringRef value, FmtContext &ctx, MethodBody &os,
 196                         bool isOptional = false);
 197   /// Generate the parser code for a variable.
 198   void genVariableParser(ParameterElement *el, FmtContext &ctx, MethodBody &os);
 199   /// Generate the parser code for a `params` directive.
 200   void genParamsParser(ParamsDirective *el, FmtContext &ctx, MethodBody &os);
 201   /// Generate the parser code for a `struct` directive.
 202   void genStructParser(StructDirective *el, FmtContext &ctx, MethodBody &os);
 203   /// Generate the parser code for a `custom` directive.
 204   void genCustomParser(CustomDirective *el, FmtContext &ctx, MethodBody &os,
 205                        bool isOptional = false);
 206   /// Generate the parser code for an optional group.
 207   void genOptionalGroupParser(OptionalElement *el, FmtContext &ctx,
 208                               MethodBody &os);
 209
 210   /// Generate the printer code for a specific format element.
 211   void genElementPrinter(FormatElement *el, FmtContext &ctx, MethodBody &os);
 212   /// Generate the printer code for a literal.
 213   void genLiteralPrinter(StringRef value, FmtContext &ctx, MethodBody &os);
 214   /// Generate the printer code for a variable.
 215   void genVariablePrinter(ParameterElement *el, FmtContext &ctx, MethodBody &os,
 216                           bool skipGuard = false);
 217   /// Generate a printer for comma-separated parameters.
 218   void genCommaSeparatedPrinter(ArrayRef<ParameterElement *> params,
 219                                 FmtContext &ctx, MethodBody &os,
 220                                 function_ref<void(ParameterElement *)> extra);
 221   /// Generate the printer code for a `params` directive.
 222   void genParamsPrinter(ParamsDirective *el, FmtContext &ctx, MethodBody &os);
 223   /// Generate the printer code for a `struct` directive.
 224   void genStructPrinter(StructDirective *el, FmtContext &ctx, MethodBody &os);
 225   /// Generate the printer code for a `custom` directive.
 226   void genCustomPrinter(CustomDirective *el, FmtContext &ctx, MethodBody &os);
 227   /// Generate the printer code for an optional group.
 228   void genOptionalGroupPrinter(OptionalElement *el, FmtContext &ctx,
 229                                MethodBody &os);
 230   /// Generate a printer (or space eraser) for a whitespace element.
 231   void genWhitespacePrinter(WhitespaceElement *el, FmtContext &ctx,
 232                             MethodBody &os);
 233
 234   /// The ODS definition of the attribute or type whose format is being used to
 235   /// generate a parser and printer.
 236   const AttrOrTypeDef &def;
 237   /// The list of top-level format elements returned by the assembly format
 238   /// parser.
 239   std::vector<FormatElement *> elements;
 240
 241   /// Flags for printing spaces.
 242   bool shouldEmitSpace = false;
 243   bool lastWasPunctuation = false;
 244 };
 245 } // namespace
 246
 247 //===----------------------------------------------------------------------===//
 248 // ParserGen
 249 //===----------------------------------------------------------------------===//
 250
 251 /// Generate a special-case "parser" for an attribute's self type parameter. The
 252 /// self type parameter has special handling in the assembly format in that it
 253 /// is derived from the optional trailing colon type after the attribute.
 254 static void genAttrSelfTypeParser(MethodBody &os, const FmtContext &ctx,
 255                                   const AttributeSelfTypeParameter &param) {
 256   // "Parser" for an attribute self type parameter that checks the
 257   // optionally-parsed trailing colon type.
 258   //
 259   // $0: The C++ storage class of the type parameter.
 260   // $1: The self type parameter name.
 261   const char *const selfTypeParser = R"(
 262 if ($_type) {
 263   if (auto reqType = ::llvm::dyn_cast<$0>($_type)) {
 264     _result_$1 = reqType;
 265   } else {
 266     $_parser.emitError($_loc, "invalid kind of type specified");
 267     return {};
 268   }
 269 })";
 270
 271   // If the attribute self type parameter is required, emit code that emits an
 272   // error if the trailing type was not parsed.
 273   const char *const selfTypeRequired = R"( else {
 274   $_parser.emitError($_loc, "expected a trailing type");
 275   return {};
 276 })";
 277
 278   os << tgfmt(selfTypeParser, &ctx, param.getCppStorageType(), param.getName());
 279   if (!param.isOptional())
 280     os << tgfmt(selfTypeRequired, &ctx);
 281   os << "\n";
 282 }
 283
 284 void DefFormat::genParser(MethodBody &os) {
 285   FmtContext ctx;
 286   ctx.addSubst("_parser", "odsParser");
 287   ctx.addSubst("_ctxt", "odsParser.getContext()");
 288   ctx.withBuilder("odsBuilder");
 289   if (isa<AttrDef>(def))
 290     ctx.addSubst("_type", "odsType");
 291   os.indent();
 292   os << "::mlir::Builder odsBuilder(odsParser.getContext());\n";
 293
 294   // Store the initial location of the parser.
 295   ctx.addSubst("_loc", "odsLoc");
 296   os << tgfmt("::llvm::SMLoc $_loc = $_parser.getCurrentLocation();\n"
 297               "(void) $_loc;\n",
 298               &ctx);
 299
 300   // Declare variables to store all of the parameters. Allocated parameters
 301   // such as `ArrayRef` and `StringRef` must provide a `storageType`. Store
 302   // FailureOr<T> to defer type construction for parameters that are parsed in
 303   // a loop (parsers return FailureOr anyways).
 304   ArrayRef<AttrOrTypeParameter> params = def.getParameters();
 305   for (const AttrOrTypeParameter &param : params) {
 306     os << formatv("::mlir::FailureOr<{0}> _result_{1};\n",
 307                   param.getCppStorageType(), param.getName());
 308     if (auto *selfTypeParam = dyn_cast<AttributeSelfTypeParameter>(&param))
 309       genAttrSelfTypeParser(os, ctx, *selfTypeParam);
 310   }
 311
 312   // Generate call to each parameter parser.
 313   for (FormatElement *el : elements)
 314     genElementParser(el, ctx, os);
 315
 316   // Emit an assert for each mandatory parameter. Triggering an assert means
 317   // the generated parser is incorrect (i.e. there is a bug in this code).
 318   for (const AttrOrTypeParameter &param : params) {
 319     if (param.isOptional())
 320       continue;
 321     os << formatv("assert(::mlir::succeeded(_result_{0}));\n", param.getName());
 322   }
 323
 324   // Generate call to the attribute or type builder. Use the checked getter
 325   // if one was generated.
 326   if (def.genVerifyDecl() || def.genVerifyInvariantsImpl()) {
 327     os << tgfmt("return $_parser.getChecked<$0>($_loc, $_parser.getContext()",
 328                 &ctx, def.getCppClassName());
 329   } else {
 330     os << tgfmt("return $0::get($_parser.getContext()", &ctx,
 331                 def.getCppClassName());
 332   }
 333   for (const AttrOrTypeParameter &param : params) {
 334     os << ",\n    ";
 335     std::string paramSelfStr;
 336     llvm::raw_string_ostream selfOs(paramSelfStr);
 337     if (std::optional<StringRef> defaultValue = param.getDefaultValue()) {
 338       selfOs << formatv("(_result_{0}.value_or(", param.getName())
 339              << tgfmt(*defaultValue, &ctx) << "))";
 340     } else {
 341       selfOs << formatv("(*_result_{0})", param.getName());
 342     }
 343     ctx.addSubst(param.getName(), selfOs.str());
 344     os << param.getCppType() << "("
 345        << tgfmt(param.getConvertFromStorage(), &ctx.withSelf(selfOs.str()))
 346        << ")";
 347   }
 348   os << ");";
 349 }
 350
 351 void DefFormat::genElementParser(FormatElement *el, FmtContext &ctx,
 352                                  MethodBody &os) {
 353   if (auto *literal = dyn_cast<LiteralElement>(el))
 354     return genLiteralParser(literal->getSpelling(), ctx, os);
 355   if (auto *var = dyn_cast<ParameterElement>(el))
 356     return genVariableParser(var, ctx, os);
 357   if (auto *params = dyn_cast<ParamsDirective>(el))
 358     return genParamsParser(params, ctx, os);
 359   if (auto *strct = dyn_cast<StructDirective>(el))
 360     return genStructParser(strct, ctx, os);
 361   if (auto *custom = dyn_cast<CustomDirective>(el))
 362     return genCustomParser(custom, ctx, os);
 363   if (auto *optional = dyn_cast<OptionalElement>(el))
 364     return genOptionalGroupParser(optional, ctx, os);
 365   if (isa<WhitespaceElement>(el))
 366     return;
 367
 368   llvm_unreachable("unknown format element");
 369 }
 370
 371 void DefFormat::genLiteralParser(StringRef value, FmtContext &ctx,
 372                                  MethodBody &os, bool isOptional) {
 373   os << "// Parse literal '" << value << "'\n";
 374   os << tgfmt("if ($_parser.parse", &ctx);
 375   if (isOptional)
 376     os << "Optional";
 377   if (value.front() == '_' || isalpha(value.front())) {
 378     os << "Keyword(\"" << value << "\")";
 379   } else {
 380     os << StringSwitch<StringRef>(value)
 381               .Case("->", "Arrow")
 382               .Case(":", "Colon")
 383               .Case(",", "Comma")
 384               .Case("=", "Equal")
 385               .Case("<", "Less")
 386               .Case(">", "Greater")
 387               .Case("{", "LBrace")
 388               .Case("}", "RBrace")
 389               .Case("(", "LParen")
 390               .Case(")", "RParen")
 391               .Case("[", "LSquare")
 392               .Case("]", "RSquare")
 393               .Case("?", "Question")
 394               .Case("+", "Plus")
 395               .Case("*", "Star")
 396               .Case("...", "Ellipsis")
 397        << "()";
 398   }
 399   if (isOptional) {
 400     // Leave the `if` unclosed to guard optional groups.
 401     return;
 402   }
 403   // Parser will emit an error
 404   os << ") return {};\n";
 405 }
 406
 407 void DefFormat::genVariableParser(ParameterElement *el, FmtContext &ctx,
 408                                   MethodBody &os) {
 409   // Check for a custom parser. Use the default attribute parser otherwise.
 410   const AttrOrTypeParameter &param = el->getParam();
 411   auto customParser = param.getParser();
 412   auto parser =
 413       customParser ? *customParser : StringRef(defaultParameterParser);
 414
 415   // If the variable points to a dialect specific entity (type of attribute),
 416   // we force load the dialect now before trying to parse it.
 417   std::string dialectLoading;
 418   if (auto *defInit = dyn_cast<llvm::DefInit>(param.getDef())) {
 419     auto *dialectValue = defInit->getDef()->getValue("dialect");
 420     if (dialectValue) {
 421       if (auto *dialectInit =
 422               dyn_cast<llvm::DefInit>(dialectValue->getValue())) {
 423         Dialect dialect(dialectInit->getDef());
 424         auto cppNamespace = dialect.getCppNamespace();
 425         std::string name = dialect.getCppClassName();
 426         if (name != "BuiltinDialect" || cppNamespace != "::mlir") {
 427           dialectLoading = ("\nodsParser.getContext()->getOrLoadDialect<" +
 428                             cppNamespace + "::" + name + ">();")
 429                                .str();
 430         }
 431       }
 432     }
 433   }
 434   os << formatv(variableParser, param.getName(),
 435                 tgfmt(parser, &ctx, param.getCppStorageType()),
 436                 tgfmt(parserErrorStr, &ctx), def.getName(), param.getCppType(),
 437                 dialectLoading);
 438 }
 439
 440 void DefFormat::genParamsParser(ParamsDirective *el, FmtContext &ctx,
 441                                 MethodBody &os) {
 442   os << "// Parse parameter list\n";
 443
 444   // If there are optional parameters, we need to switch to `parseOptionalComma`
 445   // if there are no more required parameters after a certain point.
 446   bool hasOptional = el->hasOptionalParams();
 447   if (hasOptional) {
 448     // Wrap everything in a do-while so that we can `break`.
 449     os << "do {\n";
 450     os.indent();
 451   }
 452
 453   ArrayRef<ParameterElement *> params = el->getParams();
 454   using IteratorT = ParameterElement *const *;
 455   IteratorT it = params.begin();
 456
 457   // Find the last required parameter. Commas become optional aftewards.
 458   // Note: IteratorT's copy assignment is deleted.
 459   ParameterElement *lastReq = nullptr;
 460   for (ParameterElement *param : params)
 461     if (!param->isOptional())
 462       lastReq = param;
 463   IteratorT lastReqIt = lastReq ? llvm::find(params, lastReq) : params.begin();
 464
 465   auto eachFn = [&](ParameterElement *el) { genVariableParser(el, ctx, os); };
 466   auto betweenFn = [&](IteratorT it) {
 467     ParameterElement *el = *std::prev(it);
 468     // Parse a comma if the last optional parameter had a value.
 469     if (el->isOptional()) {
 470       os << formatv("if (::mlir::succeeded(_result_{0}) && !({1})) {{\n",
 471                     el->getName(),
 472                     el->genIsPresent(ctx, "(*_result_" + el->getName() + ")"));
 473       os.indent();
 474     }
 475     if (it <= lastReqIt) {
 476       genLiteralParser(",", ctx, os);
 477     } else {
 478       genLiteralParser(",", ctx, os, /*isOptional=*/true);
 479       os << ") break;\n";
 480     }
 481     if (el->isOptional())
 482       os.unindent() << "}\n";
 483   };
 484
 485   // llvm::interleave
 486   if (it != params.end()) {
 487     eachFn(*it++);
 488     for (IteratorT e = params.end(); it != e; ++it) {
 489       betweenFn(it);
 490       eachFn(*it);
 491     }
 492   }
 493
 494   if (hasOptional)
 495     os.unindent() << "} while(false);\n";
 496 }
 497
 498 void DefFormat::genStructParser(StructDirective *el, FmtContext &ctx,
 499                                 MethodBody &os) {
 500   // Loop declaration for struct parser with only required parameters.
 501   //
 502   // $0: Number of expected parameters.
 503   const char *const loopHeader = R"(
 504   for (unsigned odsStructIndex = 0; odsStructIndex < $0; ++odsStructIndex) {
 505 )";
 506
 507   // Loop body start for struct parser.
 508   const char *const loopStart = R"(
 509     ::llvm::StringRef _paramKey;
 510     if ($_parser.parseKeyword(&_paramKey)) {
 511       $_parser.emitError($_parser.getCurrentLocation(),
 512                          "expected a parameter name in struct");
 513       return {};
 514     }
 515     if (!_loop_body(_paramKey)) return {};
 516 )";
 517
 518   // Struct parser loop end. Check for duplicate or unknown struct parameters.
 519   //
 520   // {0}: Code template for printing an error.
 521   const char *const loopEnd = R"({{
 522   {0}"duplicate or unknown struct parameter name: ") << _paramKey;
 523   return {{};
 524 }
 525 )";
 526
 527   // Struct parser loop terminator. Parse a comma except on the last element.
 528   //
 529   // {0}: Number of elements in the struct.
 530   const char *const loopTerminator = R"(
 531   if ((odsStructIndex != {0} - 1) && odsParser.parseComma())
 532     return {{};
 533 }
 534 )";
 535
 536   // Check that a mandatory parameter was parse.
 537   //
 538   // {0}: Name of the parameter.
 539   const char *const checkParam = R"(
 540     if (!_seen_{0}) {
 541       {1}"struct is missing required parameter: ") << "{0}";
 542       return {{};
 543     }
 544 )";
 545
 546   // First iteration of the loop parsing an optional struct.
 547   const char *const optionalStructFirst = R"(
 548   ::llvm::StringRef _paramKey;
 549   if (!$_parser.parseOptionalKeyword(&_paramKey)) {
 550     if (!_loop_body(_paramKey)) return {};
 551     while (!$_parser.parseOptionalComma()) {
 552 )";
 553
 554   os << "// Parse parameter struct\n";
 555
 556   // Declare a "seen" variable for each key.
 557   for (ParameterElement *param : el->getParams())
 558     os << formatv("bool _seen_{0} = false;\n", param->getName());
 559
 560   // Generate the body of the parsing loop inside a lambda.
 561   os << "{\n";
 562   os.indent()
 563       << "const auto _loop_body = [&](::llvm::StringRef _paramKey) -> bool {\n";
 564   genLiteralParser("=", ctx, os.indent());
 565   for (ParameterElement *param : el->getParams()) {
 566     os << formatv("if (!_seen_{0} && _paramKey == \"{0}\") {\n"
 567                   "  _seen_{0} = true;\n",
 568                   param->getName());
 569     genVariableParser(param, ctx, os.indent());
 570     os.unindent() << "} else ";
 571     // Print the check for duplicate or unknown parameter.
 572   }
 573   os.getStream().printReindented(strfmt(loopEnd, tgfmt(parserErrorStr, &ctx)));
 574   os << "return true;\n";
 575   os.unindent() << "};\n";
 576
 577   // Generate the parsing loop. If optional parameters are present, then the
 578   // parse loop is guarded by commas.
 579   unsigned numOptional = llvm::count_if(el->getParams(), paramIsOptional);
 580   if (numOptional) {
 581     // If the struct itself is optional, pull out the first iteration.
 582     if (numOptional == el->getNumParams()) {
 583       os.getStream().printReindented(tgfmt(optionalStructFirst, &ctx).str());
 584       os.indent();
 585     } else {
 586       os << "do {\n";
 587     }
 588   } else {
 589     os.getStream().printReindented(
 590         tgfmt(loopHeader, &ctx, el->getNumParams()).str());
 591   }
 592   os.indent();
 593   os.getStream().printReindented(tgfmt(loopStart, &ctx).str());
 594   os.unindent();
 595
 596   // Print the loop terminator. For optional parameters, we have to check that
 597   // all mandatory parameters have been parsed.
 598   // The whole struct is optional if all its parameters are optional.
 599   if (numOptional) {
 600     if (numOptional == el->getNumParams()) {
 601       os << "}\n";
 602       os.unindent() << "}\n";
 603     } else {
 604       os << tgfmt("} while(!$_parser.parseOptionalComma());\n", &ctx);
 605       for (ParameterElement *param : el->getParams()) {
 606         if (param->isOptional())
 607           continue;
 608         os.getStream().printReindented(
 609             strfmt(checkParam, param->getName(), tgfmt(parserErrorStr, &ctx)));
 610       }
 611     }
 612   } else {
 613     // Because the loop loops N times and each non-failing iteration sets 1 of
 614     // N flags, successfully exiting the loop means that all parameters have
 615     // been seen. `parseOptionalComma` would cause issues with any formats that
 616     // use "struct(...) `,`" beacuse structs aren't sounded by braces.
 617     os.getStream().printReindented(strfmt(loopTerminator, el->getNumParams()));
 618   }
 619   os.unindent() << "}\n";
 620 }
 621
 622 void DefFormat::genCustomParser(CustomDirective *el, FmtContext &ctx,
 623                                 MethodBody &os, bool isOptional) {
 624   os << "{\n";
 625   os.indent();
 626
 627   // Bound variables are passed directly to the parser as `FailureOr<T> &`.
 628   // Referenced variables are passed as `T`. The custom parser fails if it
 629   // returns failure or if any of the required parameters failed.
 630   os << tgfmt("auto odsCustomLoc = $_parser.getCurrentLocation();\n", &ctx);
 631   os << "(void)odsCustomLoc;\n";
 632   os << tgfmt("auto odsCustomResult = parse$0($_parser", &ctx, el->getName());
 633   os.indent();
 634   for (FormatElement *arg : el->getArguments()) {
 635     os << ",\n";
 636     if (auto *param = dyn_cast<ParameterElement>(arg))
 637       os << "::mlir::detail::unwrapForCustomParse(_result_" << param->getName()
 638          << ")";
 639     else if (auto *ref = dyn_cast<RefDirective>(arg))
 640       os << "*_result_" << cast<ParameterElement>(ref->getArg())->getName();
 641     else
 642       os << tgfmt(cast<StringElement>(arg)->getValue(), &ctx);
 643   }
 644   os.unindent() << ");\n";
 645   if (isOptional) {
 646     os << "if (!odsCustomResult.has_value()) return {};\n";
 647     os << "if (::mlir::failed(*odsCustomResult)) return ::mlir::failure();\n";
 648   } else {
 649     os << "if (::mlir::failed(odsCustomResult)) return {};\n";
 650   }
 651   for (FormatElement *arg : el->getArguments()) {
 652     if (auto *param = dyn_cast<ParameterElement>(arg)) {
 653       if (param->isOptional())
 654         continue;
 655       os << formatv("if (::mlir::failed(_result_{0})) {{\n", param->getName());
 656       os.indent() << tgfmt("$_parser.emitError(odsCustomLoc, ", &ctx)
 657                   << "\"custom parser failed to parse parameter '"
 658                   << param->getName() << "'\");\n";
 659       os << "return " << (isOptional ? "::mlir::failure()" : "{}") << ";\n";
 660       os.unindent() << "}\n";
 661     }
 662   }
 663
 664   os.unindent() << "}\n";
 665 }
 666
 667 void DefFormat::genOptionalGroupParser(OptionalElement *el, FmtContext &ctx,
 668                                        MethodBody &os) {
 669   ArrayRef<FormatElement *> thenElements =
 670       el->getThenElements(/*parseable=*/true);
 671
 672   FormatElement *first = thenElements.front();
 673   const auto guardOn = [&](auto params) {
 674     os << "if (!(";
 675     llvm::interleave(
 676         params, os,
 677         [&](ParameterElement *el) {
 678           os << formatv("(::mlir::succeeded(_result_{0}) && *_result_{0})",
 679                         el->getName());
 680         },
 681         " || ");
 682     os << ")) {\n";
 683   };
 684   if (auto *literal = dyn_cast<LiteralElement>(first)) {
 685     genLiteralParser(literal->getSpelling(), ctx, os, /*isOptional=*/true);
 686     os << ") {\n";
 687   } else if (auto *param = dyn_cast<ParameterElement>(first)) {
 688     genVariableParser(param, ctx, os);
 689     guardOn(llvm::ArrayRef(param));
 690   } else if (auto *params = dyn_cast<ParamsDirective>(first)) {
 691     genParamsParser(params, ctx, os);
 692     guardOn(params->getParams());
 693   } else if (auto *custom = dyn_cast<CustomDirective>(first)) {
 694     os << "if (auto result = [&]() -> ::mlir::OptionalParseResult {\n";
 695     os.indent();
 696     genCustomParser(custom, ctx, os, /*isOptional=*/true);
 697     os << "return ::mlir::success();\n";
 698     os.unindent();
 699     os << "}(); result.has_value() && ::mlir::failed(*result)) {\n";
 700     os.indent();
 701     os << "return {};\n";
 702     os.unindent();
 703     os << "} else if (result.has_value()) {\n";
 704   } else {
 705     auto *strct = cast<StructDirective>(first);
 706     genStructParser(strct, ctx, os);
 707     guardOn(params->getParams());
 708   }
 709   os.indent();
 710
 711   // Generate the parsers for the rest of the thenElements.
 712   for (FormatElement *element : el->getElseElements(/*parseable=*/true))
 713     genElementParser(element, ctx, os);
 714   os.unindent() << "} else {\n";
 715   os.indent();
 716   for (FormatElement *element : thenElements.drop_front())
 717     genElementParser(element, ctx, os);
 718   os.unindent() << "}\n";
 719 }
 720
 721 //===----------------------------------------------------------------------===//
 722 // PrinterGen
 723 //===----------------------------------------------------------------------===//
 724
 725 void DefFormat::genPrinter(MethodBody &os) {
 726   FmtContext ctx;
 727   ctx.addSubst("_printer", "odsPrinter");
 728   ctx.addSubst("_ctxt", "getContext()");
 729   ctx.withBuilder("odsBuilder");
 730   os.indent();
 731   os << "::mlir::Builder odsBuilder(getContext());\n";
 732
 733   // Generate printers.
 734   shouldEmitSpace = true;
 735   lastWasPunctuation = false;
 736   for (FormatElement *el : elements)
 737     genElementPrinter(el, ctx, os);
 738 }
 739
 740 void DefFormat::genElementPrinter(FormatElement *el, FmtContext &ctx,
 741                                   MethodBody &os) {
 742   if (auto *literal = dyn_cast<LiteralElement>(el))
 743     return genLiteralPrinter(literal->getSpelling(), ctx, os);
 744   if (auto *params = dyn_cast<ParamsDirective>(el))
 745     return genParamsPrinter(params, ctx, os);
 746   if (auto *strct = dyn_cast<StructDirective>(el))
 747     return genStructPrinter(strct, ctx, os);
 748   if (auto *custom = dyn_cast<CustomDirective>(el))
 749     return genCustomPrinter(custom, ctx, os);
 750   if (auto *var = dyn_cast<ParameterElement>(el))
 751     return genVariablePrinter(var, ctx, os);
 752   if (auto *optional = dyn_cast<OptionalElement>(el))
 753     return genOptionalGroupPrinter(optional, ctx, os);
 754   if (auto *whitespace = dyn_cast<WhitespaceElement>(el))
 755     return genWhitespacePrinter(whitespace, ctx, os);
 756
 757   llvm::PrintFatalError("unsupported format element");
 758 }
 759
 760 void DefFormat::genLiteralPrinter(StringRef value, FmtContext &ctx,
 761                                   MethodBody &os) {
 762   // Don't insert a space before certain punctuation.
 763   bool needSpace =
 764       shouldEmitSpace && shouldEmitSpaceBefore(value, lastWasPunctuation);
 765   os << tgfmt("$_printer$0 << \"$1\";\n", &ctx, needSpace ? " << ' '" : "",
 766               value);
 767
 768   // Update the flags.
 769   shouldEmitSpace =
 770       value.size() != 1 || !StringRef("<({[").contains(value.front());
 771   lastWasPunctuation = value.front() != '_' && !isalpha(value.front());
 772 }
 773
 774 void DefFormat::genVariablePrinter(ParameterElement *el, FmtContext &ctx,
 775                                    MethodBody &os, bool skipGuard) {
 776   const AttrOrTypeParameter &param = el->getParam();
 777   ctx.withSelf(param.getAccessorName() + "()");
 778
 779   // Guard the printer on the presence of optional parameters and that they
 780   // aren't equal to their default values (if they have one).
 781   if (el->isOptional() && !skipGuard) {
 782     el->genPrintGuard(ctx, os << "if (") << ") {\n";
 783     os.indent();
 784   }
 785
 786   // Insert a space before the next parameter, if necessary.
 787   if (shouldEmitSpace || !lastWasPunctuation)
 788     os << tgfmt("$_printer << ' ';\n", &ctx);
 789   shouldEmitSpace = true;
 790   lastWasPunctuation = false;
 791
 792   if (el->shouldBeQualified())
 793     os << tgfmt(qualifiedParameterPrinter, &ctx) << ";\n";
 794   else if (auto printer = param.getPrinter())
 795     os << tgfmt(*printer, &ctx) << ";\n";
 796   else
 797     os << tgfmt(defaultParameterPrinter, &ctx) << ";\n";
 798
 799   if (el->isOptional() && !skipGuard)
 800     os.unindent() << "}\n";
 801 }
 802
 803 /// Generate code to guard printing on the presence of any optional parameters.
 804 template <typename ParameterRange>
 805 static void guardOnAny(FmtContext &ctx, MethodBody &os, ParameterRange &&params,
 806                        bool inverted = false) {
 807   os << "if (";
 808   if (inverted)
 809     os << "!(";
 810   llvm::interleave(
 811       params, os,
 812       [&](ParameterElement *param) { param->genPrintGuard(ctx, os); }, " || ");
 813   if (inverted)
 814     os << ")";
 815   os << ") {\n";
 816   os.indent();
 817 }
 818
 819 void DefFormat::genCommaSeparatedPrinter(
 820     ArrayRef<ParameterElement *> params, FmtContext &ctx, MethodBody &os,
 821     function_ref<void(ParameterElement *)> extra) {
 822   // Emit a space if necessary, but only if the struct is present.
 823   if (shouldEmitSpace || !lastWasPunctuation) {
 824     bool allOptional = llvm::all_of(params, paramIsOptional);
 825     if (allOptional)
 826       guardOnAny(ctx, os, params);
 827     os << tgfmt("$_printer << ' ';\n", &ctx);
 828     if (allOptional)
 829       os.unindent() << "}\n";
 830   }
 831
 832   // The first printed element does not need to emit a comma.
 833   os << "{\n";
 834   os.indent() << "bool _firstPrinted = true;\n";
 835   for (ParameterElement *param : params) {
 836     if (param->isOptional()) {
 837       param->genPrintGuard(ctx, os << "if (") << ") {\n";
 838       os.indent();
 839     }
 840     os << tgfmt("if (!_firstPrinted) $_printer << \", \";\n", &ctx);
 841     os << "_firstPrinted = false;\n";
 842     extra(param);
 843     shouldEmitSpace = false;
 844     lastWasPunctuation = true;
 845     genVariablePrinter(param, ctx, os);
 846     if (param->isOptional())
 847       os.unindent() << "}\n";
 848   }
 849   os.unindent() << "}\n";
 850 }
 851
 852 void DefFormat::genParamsPrinter(ParamsDirective *el, FmtContext &ctx,
 853                                  MethodBody &os) {
 854   genCommaSeparatedPrinter(llvm::to_vector(el->getParams()), ctx, os,
 855                            [&](ParameterElement *param) {});
 856 }
 857
 858 void DefFormat::genStructPrinter(StructDirective *el, FmtContext &ctx,
 859                                  MethodBody &os) {
 860   genCommaSeparatedPrinter(
 861       llvm::to_vector(el->getParams()), ctx, os, [&](ParameterElement *param) {
 862         os << tgfmt("$_printer << \"$0 = \";\n", &ctx, param->getName());
 863       });
 864 }
 865
 866 void DefFormat::genCustomPrinter(CustomDirective *el, FmtContext &ctx,
 867                                  MethodBody &os) {
 868   // Insert a space before the custom directive, if necessary.
 869   if (shouldEmitSpace || !lastWasPunctuation)
 870     os << tgfmt("$_printer << ' ';\n", &ctx);
 871   shouldEmitSpace = true;
 872   lastWasPunctuation = false;
 873
 874   os << tgfmt("print$0($_printer", &ctx, el->getName());
 875   os.indent();
 876   for (FormatElement *arg : el->getArguments()) {
 877     os << ",\n";
 878     if (auto *param = dyn_cast<ParameterElement>(arg)) {
 879       os << param->getParam().getAccessorName() << "()";
 880     } else if (auto *ref = dyn_cast<RefDirective>(arg)) {
 881       os << cast<ParameterElement>(ref->getArg())->getParam().getAccessorName()
 882          << "()";
 883     } else {
 884       os << tgfmt(cast<StringElement>(arg)->getValue(), &ctx);
 885     }
 886   }
 887   os.unindent() << ");\n";
 888 }
 889
 890 void DefFormat::genOptionalGroupPrinter(OptionalElement *el, FmtContext &ctx,
 891                                         MethodBody &os) {
 892   FormatElement *anchor = el->getAnchor();
 893   if (auto *param = dyn_cast<ParameterElement>(anchor)) {
 894     guardOnAny(ctx, os, llvm::ArrayRef(param), el->isInverted());
 895   } else if (auto *params = dyn_cast<ParamsDirective>(anchor)) {
 896     guardOnAny(ctx, os, params->getParams(), el->isInverted());
 897   } else if (auto *strct = dyn_cast<StructDirective>(anchor)) {
 898     guardOnAny(ctx, os, strct->getParams(), el->isInverted());
 899   } else {
 900     auto *custom = cast<CustomDirective>(anchor);
 901     guardOnAny(ctx, os,
 902                llvm::make_filter_range(
 903                    llvm::map_range(custom->getArguments(),
 904                                    [](FormatElement *el) {
 905                                      return dyn_cast<ParameterElement>(el);
 906                                    }),
 907                    [](ParameterElement *param) { return !!param; }),
 908                el->isInverted());
 909   }
 910   // Generate the printer for the contained elements.
 911   {
 912     llvm::SaveAndRestore shouldEmitSpaceFlag(shouldEmitSpace);
 913     llvm::SaveAndRestore lastWasPunctuationFlag(lastWasPunctuation);
 914     for (FormatElement *element : el->getThenElements())
 915       genElementPrinter(element, ctx, os);
 916   }
 917   os.unindent() << "} else {\n";
 918   os.indent();
 919   for (FormatElement *element : el->getElseElements())
 920     genElementPrinter(element, ctx, os);
 921   os.unindent() << "}\n";
 922 }
 923
 924 void DefFormat::genWhitespacePrinter(WhitespaceElement *el, FmtContext &ctx,
 925                                      MethodBody &os) {
 926   if (el->getValue() == "\\n") {
 927     // FIXME: The newline should be `printer.printNewLine()`, i.e., handled by
 928     // the printer.
 929     os << tgfmt("$_printer << '\\n';\n", &ctx);
 930   } else if (!el->getValue().empty()) {
 931     os << tgfmt("$_printer << \"$0\";\n", &ctx, el->getValue());
 932   } else {
 933     lastWasPunctuation = true;
 934   }
 935   shouldEmitSpace = false;
 936 }
 937
 938 //===----------------------------------------------------------------------===//
 939 // DefFormatParser
 940 //===----------------------------------------------------------------------===//
 941
 942 namespace {
 943 class DefFormatParser : public FormatParser {
 944 public:
 945   DefFormatParser(llvm::SourceMgr &mgr, const AttrOrTypeDef &def)
 946       : FormatParser(mgr, def.getLoc()[0]), def(def),
 947         seenParams(def.getNumParameters()) {}
 948
 949   /// Parse the attribute or type format and create the format elements.
 950   FailureOr<DefFormat> parse();
 951
 952 protected:
 953   /// Verify the parsed elements.
 954   LogicalResult verify(SMLoc loc, ArrayRef<FormatElement *> elements) override;
 955   /// Verify the elements of a custom directive.
 956   LogicalResult
 957   verifyCustomDirectiveArguments(SMLoc loc,
 958                                  ArrayRef<FormatElement *> arguments) override;
 959   /// Verify the elements of an optional group.
 960   LogicalResult verifyOptionalGroupElements(SMLoc loc,
 961                                             ArrayRef<FormatElement *> elements,
 962                                             FormatElement *anchor) override;
 963
 964   LogicalResult markQualified(SMLoc loc, FormatElement *element) override;
 965
 966   /// Parse an attribute or type variable.
 967   FailureOr<FormatElement *> parseVariableImpl(SMLoc loc, StringRef name,
 968                                                Context ctx) override;
 969   /// Parse an attribute or type format directive.
 970   FailureOr<FormatElement *>
 971   parseDirectiveImpl(SMLoc loc, FormatToken::Kind kind, Context ctx) override;
 972
 973 private:
 974   /// Parse a `params` directive.
 975   FailureOr<FormatElement *> parseParamsDirective(SMLoc loc, Context ctx);
 976   /// Parse a `struct` directive.
 977   FailureOr<FormatElement *> parseStructDirective(SMLoc loc, Context ctx);
 978
 979   /// Attribute or type tablegen def.
 980   const AttrOrTypeDef &def;
 981
 982   /// Seen attribute or type parameters.
 983   BitVector seenParams;
 984 };
 985 } // namespace
 986
 987 LogicalResult DefFormatParser::verify(SMLoc loc,
 988                                       ArrayRef<FormatElement *> elements) {
 989   // Check that all parameters are referenced in the format.
 990   for (auto [index, param] : llvm::enumerate(def.getParameters())) {
 991     if (param.isOptional())
 992       continue;
 993     if (!seenParams.test(index)) {
 994       if (isa<AttributeSelfTypeParameter>(param))
 995         continue;
 996       return emitError(loc, "format is missing reference to parameter: " +
 997                                 param.getName());
 998     }
 999     if (isa<AttributeSelfTypeParameter>(param)) {
1000       return emitError(loc,
1001                        "unexpected self type parameter in assembly format");
1002     }
1003   }
1004   if (elements.empty())
1005     return success();
1006   // A `struct` directive that contains optional parameters cannot be followed
1007   // by a comma literal, which is ambiguous.
1008   for (auto it : llvm::zip(elements.drop_back(), elements.drop_front())) {
1009     auto *structEl = dyn_cast<StructDirective>(std::get<0>(it));
1010     auto *literalEl = dyn_cast<LiteralElement>(std::get<1>(it));
1011     if (!structEl || !literalEl)
1012       continue;
1013     if (literalEl->getSpelling() == "," && structEl->hasOptionalParams()) {
1014       return emitError(loc, "`struct` directive with optional parameters "
1015                             "cannot be followed by a comma literal");
1016     }
1017   }
1018   return success();
1019 }
1020
1021 LogicalResult DefFormatParser::verifyCustomDirectiveArguments(
1022     SMLoc loc, ArrayRef<FormatElement *> arguments) {
1023   // Arguments are fully verified by the parser context.
1024   return success();
1025 }
1026
1027 LogicalResult
1028 DefFormatParser::verifyOptionalGroupElements(llvm::SMLoc loc,
1029                                              ArrayRef<FormatElement *> elements,
1030                                              FormatElement *anchor) {
1031   // `params` and `struct` directives are allowed only if all the contained
1032   // parameters are optional.
1033   for (FormatElement *el : elements) {
1034     if (auto *param = dyn_cast<ParameterElement>(el)) {
1035       if (!param->isOptional()) {
1036         return emitError(loc,
1037                          "parameters in an optional group must be optional");
1038       }
1039     } else if (auto *params = dyn_cast<ParamsDirective>(el)) {
1040       if (llvm::any_of(params->getParams(), paramNotOptional)) {
1041         return emitError(loc, "`params` directive allowed in optional group "
1042                               "only if all parameters are optional");
1043       }
1044     } else if (auto *strct = dyn_cast<StructDirective>(el)) {
1045       if (llvm::any_of(strct->getParams(), paramNotOptional)) {
1046         return emitError(loc, "`struct` is only allowed in an optional group "
1047                               "if all captured parameters are optional");
1048       }
1049     } else if (auto *custom = dyn_cast<CustomDirective>(el)) {
1050       for (FormatElement *el : custom->getArguments()) {
1051         // If the custom argument is a variable, then it must be optional.
1052         if (auto *param = dyn_cast<ParameterElement>(el))
1053           if (!param->isOptional())
1054             return emitError(loc,
1055                              "`custom` is only allowed in an optional group if "
1056                              "all captured parameters are optional");
1057       }
1058     }
1059   }
1060   // The anchor must be a parameter or one of the aforementioned directives.
1061   if (anchor) {
1062     if (!isa<ParameterElement, ParamsDirective, StructDirective,
1063              CustomDirective>(anchor)) {
1064       return emitError(
1065           loc, "optional group anchor must be a parameter or directive");
1066     }
1067     // If the anchor is a custom directive, make sure at least one of its
1068     // arguments is a bound parameter.
1069     if (auto *custom = dyn_cast<CustomDirective>(anchor)) {
1070       const auto *bound =
1071           llvm::find_if(custom->getArguments(), [](FormatElement *el) {
1072             return isa<ParameterElement>(el);
1073           });
1074       if (bound == custom->getArguments().end())
1075         return emitError(loc, "`custom` directive with no bound parameters "
1076                               "cannot be used as optional group anchor");
1077     }
1078   }
1079   return success();
1080 }
1081
1082 LogicalResult DefFormatParser::markQualified(SMLoc loc,
1083                                              FormatElement *element) {
1084   if (!isa<ParameterElement>(element))
1085     return emitError(loc, "`qualified` argument list expected a variable");
1086   cast<ParameterElement>(element)->setShouldBeQualified();
1087   return success();
1088 }
1089
1090 FailureOr<DefFormat> DefFormatParser::parse() {
1091   FailureOr<std::vector<FormatElement *>> elements = FormatParser::parse();
1092   if (failed(elements))
1093     return failure();
1094   return DefFormat(def, std::move(*elements));
1095 }
1096
1097 FailureOr<FormatElement *>
1098 DefFormatParser::parseVariableImpl(SMLoc loc, StringRef name, Context ctx) {
1099   // Lookup the parameter.
1100   ArrayRef<AttrOrTypeParameter> params = def.getParameters();
1101   auto *it = llvm::find_if(
1102       params, [&](auto &param) { return param.getName() == name; });
1103
1104   // Check that the parameter reference is valid.
1105   if (it == params.end()) {
1106     return emitError(loc,
1107                      def.getName() + " has no parameter named '" + name + "'");
1108   }
1109   auto idx = std::distance(params.begin(), it);
1110
1111   if (ctx != RefDirectiveContext) {
1112     // Check that the variable has not already been bound.
1113     if (seenParams.test(idx))
1114       return emitError(loc, "duplicate parameter '" + name + "'");
1115     seenParams.set(idx);
1116
1117     // Otherwise, to be referenced, a variable must have been bound.
1118   } else if (!seenParams.test(idx) && !isa<AttributeSelfTypeParameter>(*it)) {
1119     return emitError(loc, "parameter '" + name +
1120                               "' must be bound before it is referenced");
1121   }
1122
1123   return create<ParameterElement>(*it);
1124 }
1125
1126 FailureOr<FormatElement *>
1127 DefFormatParser::parseDirectiveImpl(SMLoc loc, FormatToken::Kind kind,
1128                                     Context ctx) {
1129
1130   switch (kind) {
1131   case FormatToken::kw_qualified:
1132     return parseQualifiedDirective(loc, ctx);
1133   case FormatToken::kw_params:
1134     return parseParamsDirective(loc, ctx);
1135   case FormatToken::kw_struct:
1136     return parseStructDirective(loc, ctx);
1137   default:
1138     return emitError(loc, "unsupported directive kind");
1139   }
1140 }
1141
1142 FailureOr<FormatElement *> DefFormatParser::parseParamsDirective(SMLoc loc,
1143                                                                  Context ctx) {
1144   // It doesn't make sense to allow references to all parameters in a custom
1145   // directive because parameters are the only things that can be bound.
1146   if (ctx != TopLevelContext && ctx != StructDirectiveContext) {
1147     return emitError(loc, "`params` can only be used at the top-level context "
1148                           "or within a `struct` directive");
1149   }
1150
1151   // Collect all of the attribute's or type's parameters and ensure that none of
1152   // the parameters have already been captured.
1153   std::vector<ParameterElement *> vars;
1154   for (const auto &it : llvm::enumerate(def.getParameters())) {
1155     if (seenParams.test(it.index())) {
1156       return emitError(loc, "`params` captures duplicate parameter: " +
1157                                 it.value().getName());
1158     }
1159     // Self-type parameters are handled separately from the rest of the
1160     // parameters.
1161     if (isa<AttributeSelfTypeParameter>(it.value()))
1162       continue;
1163     seenParams.set(it.index());
1164     vars.push_back(create<ParameterElement>(it.value()));
1165   }
1166   return create<ParamsDirective>(std::move(vars));
1167 }
1168
1169 FailureOr<FormatElement *> DefFormatParser::parseStructDirective(SMLoc loc,
1170                                                                  Context ctx) {
1171   if (ctx != TopLevelContext)
1172     return emitError(loc, "`struct` can only be used at the top-level context");
1173
1174   if (failed(parseToken(FormatToken::l_paren,
1175                         "expected '(' before `struct` argument list")))
1176     return failure();
1177
1178   // Parse variables captured by `struct`.
1179   std::vector<ParameterElement *> vars;
1180
1181   // Parse first captured parameter or a `params` directive.
1182   FailureOr<FormatElement *> var = parseElement(StructDirectiveContext);
1183   if (failed(var) || !isa<VariableElement, ParamsDirective>(*var)) {
1184     return emitError(loc,
1185                      "`struct` argument list expected a variable or directive");
1186   }
1187   if (isa<VariableElement>(*var)) {
1188     // Parse any other parameters.
1189     vars.push_back(cast<ParameterElement>(*var));
1190     while (peekToken().is(FormatToken::comma)) {
1191       consumeToken();
1192       var = parseElement(StructDirectiveContext);
1193       if (failed(var) || !isa<VariableElement>(*var))
1194         return emitError(loc, "expected a variable in `struct` argument list");
1195       vars.push_back(cast<ParameterElement>(*var));
1196     }
1197   } else {
1198     // `struct(params)` captures all parameters in the attribute or type.
1199     vars = cast<ParamsDirective>(*var)->takeParams();
1200   }
1201
1202   if (failed(parseToken(FormatToken::r_paren,
1203                         "expected ')' at the end of an argument list")))
1204     return failure();
1205
1206   return create<StructDirective>(std::move(vars));
1207 }
1208
1209 //===----------------------------------------------------------------------===//
1210 // Interface
1211 //===----------------------------------------------------------------------===//
1212
1213 void mlir::tblgen::generateAttrOrTypeFormat(const AttrOrTypeDef &def,
1214                                             MethodBody &parser,
1215                                             MethodBody &printer) {
1216   llvm::SourceMgr mgr;
1217   mgr.AddNewSourceBuffer(
1218       llvm::MemoryBuffer::getMemBuffer(*def.getAssemblyFormat()), SMLoc());
1219
1220   // Parse the custom assembly format>
1221   DefFormatParser fmtParser(mgr, def);
1222   FailureOr<DefFormat> format = fmtParser.parse();
1223   if (failed(format)) {
1224     if (formatErrorIsFatal)
1225       PrintFatalError(def.getLoc(), "failed to parse assembly format");
1226     return;
1227   }
1228
1229   // Generate the parser and printer.
1230   format->genParser(parser);
1231   format->genPrinter(printer);
1232 }