utils/TableGen/CodeGenInstruction.cpp

   1 //===- CodeGenInstruction.cpp - CodeGen Instruction Class Wrapper ---------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file implements the CodeGenInstruction class.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "CodeGenInstruction.h"
  15 #include "CodeGenTarget.h"
  16 #include "Error.h"
  17 #include "Record.h"
  18 #include "llvm/ADT/StringExtras.h"
  19 #include "llvm/ADT/StringMap.h"
  20 #include "llvm/ADT/STLExtras.h"
  21 #include <set>
  22 using namespace llvm;
  23
  24 //===----------------------------------------------------------------------===//
  25 // CGIOperandList Implementation
  26 //===----------------------------------------------------------------------===//
  27
  28 CGIOperandList::CGIOperandList(Record *R) : TheDef(R) {
  29   isPredicable = false;
  30   hasOptionalDef = false;
  31   isVariadic = false;
  32
  33   DagInit *OutDI = R->getValueAsDag("OutOperandList");
  34
  35   if (DefInit *Init = dynamic_cast<DefInit*>(OutDI->getOperator())) {
  36     if (Init->getDef()->getName() != "outs")
  37       throw R->getName() + ": invalid def name for output list: use 'outs'";
  38   } else
  39     throw R->getName() + ": invalid output list: use 'outs'";
  40
  41   NumDefs = OutDI->getNumArgs();
  42
  43   DagInit *InDI = R->getValueAsDag("InOperandList");
  44   if (DefInit *Init = dynamic_cast<DefInit*>(InDI->getOperator())) {
  45     if (Init->getDef()->getName() != "ins")
  46       throw R->getName() + ": invalid def name for input list: use 'ins'";
  47   } else
  48     throw R->getName() + ": invalid input list: use 'ins'";
  49
  50   unsigned MIOperandNo = 0;
  51   std::set<std::string> OperandNames;
  52   for (unsigned i = 0, e = InDI->getNumArgs()+OutDI->getNumArgs(); i != e; ++i){
  53     Init *ArgInit;
  54     std::string ArgName;
  55     if (i < NumDefs) {
  56       ArgInit = OutDI->getArg(i);
  57       ArgName = OutDI->getArgName(i);
  58     } else {
  59       ArgInit = InDI->getArg(i-NumDefs);
  60       ArgName = InDI->getArgName(i-NumDefs);
  61     }
  62
  63     DefInit *Arg = dynamic_cast<DefInit*>(ArgInit);
  64     if (!Arg)
  65       throw "Illegal operand for the '" + R->getName() + "' instruction!";
  66
  67     Record *Rec = Arg->getDef();
  68     std::string PrintMethod = "printOperand";
  69     std::string EncoderMethod;
  70     unsigned NumOps = 1;
  71     DagInit *MIOpInfo = 0;
  72     if (Rec->isSubClassOf("RegisterOperand")) {
  73       PrintMethod = Rec->getValueAsString("PrintMethod");
  74     } else if (Rec->isSubClassOf("Operand")) {
  75       PrintMethod = Rec->getValueAsString("PrintMethod");
  76       // If there is an explicit encoder method, use it.
  77       EncoderMethod = Rec->getValueAsString("EncoderMethod");
  78       MIOpInfo = Rec->getValueAsDag("MIOperandInfo");
  79
  80       // Verify that MIOpInfo has an 'ops' root value.
  81       if (!dynamic_cast<DefInit*>(MIOpInfo->getOperator()) ||
  82           dynamic_cast<DefInit*>(MIOpInfo->getOperator())
  83           ->getDef()->getName() != "ops")
  84         throw "Bad value for MIOperandInfo in operand '" + Rec->getName() +
  85         "'\n";
  86
  87       // If we have MIOpInfo, then we have #operands equal to number of entries
  88       // in MIOperandInfo.
  89       if (unsigned NumArgs = MIOpInfo->getNumArgs())
  90         NumOps = NumArgs;
  91
  92       if (Rec->isSubClassOf("PredicateOperand"))
  93         isPredicable = true;
  94       else if (Rec->isSubClassOf("OptionalDefOperand"))
  95         hasOptionalDef = true;
  96     } else if (Rec->getName() == "variable_ops") {
  97       isVariadic = true;
  98       continue;
  99     } else if (!Rec->isSubClassOf("RegisterClass") &&
 100                !Rec->isSubClassOf("PointerLikeRegClass") &&
 101                Rec->getName() != "unknown")
 102       throw "Unknown operand class '" + Rec->getName() +
 103       "' in '" + R->getName() + "' instruction!";
 104
 105     // Check that the operand has a name and that it's unique.
 106     if (ArgName.empty())
 107       throw "In instruction '" + R->getName() + "', operand #" + utostr(i) +
 108       " has no name!";
 109     if (!OperandNames.insert(ArgName).second)
 110       throw "In instruction '" + R->getName() + "', operand #" + utostr(i) +
 111       " has the same name as a previous operand!";
 112
 113     OperandList.push_back(OperandInfo(Rec, ArgName, PrintMethod, EncoderMethod,
 114                                       MIOperandNo, NumOps, MIOpInfo));
 115     MIOperandNo += NumOps;
 116   }
 117
 118
 119   // Make sure the constraints list for each operand is large enough to hold
 120   // constraint info, even if none is present.
 121   for (unsigned i = 0, e = OperandList.size(); i != e; ++i)
 122     OperandList[i].Constraints.resize(OperandList[i].MINumOperands);
 123 }
 124
 125
 126 /// getOperandNamed - Return the index of the operand with the specified
 127 /// non-empty name.  If the instruction does not have an operand with the
 128 /// specified name, throw an exception.
 129 ///
 130 unsigned CGIOperandList::getOperandNamed(StringRef Name) const {
 131   unsigned OpIdx;
 132   if (hasOperandNamed(Name, OpIdx)) return OpIdx;
 133   throw "'" + TheDef->getName() + "' does not have an operand named '$" +
 134     Name.str() + "'!";
 135 }
 136
 137 /// hasOperandNamed - Query whether the instruction has an operand of the
 138 /// given name. If so, return true and set OpIdx to the index of the
 139 /// operand. Otherwise, return false.
 140 bool CGIOperandList::hasOperandNamed(StringRef Name, unsigned &OpIdx) const {
 141   assert(!Name.empty() && "Cannot search for operand with no name!");
 142   for (unsigned i = 0, e = OperandList.size(); i != e; ++i)
 143     if (OperandList[i].Name == Name) {
 144       OpIdx = i;
 145       return true;
 146     }
 147   return false;
 148 }
 149
 150 std::pair<unsigned,unsigned>
 151 CGIOperandList::ParseOperandName(const std::string &Op, bool AllowWholeOp) {
 152   if (Op.empty() || Op[0] != '$')
 153     throw TheDef->getName() + ": Illegal operand name: '" + Op + "'";
 154
 155   std::string OpName = Op.substr(1);
 156   std::string SubOpName;
 157
 158   // Check to see if this is $foo.bar.
 159   std::string::size_type DotIdx = OpName.find_first_of(".");
 160   if (DotIdx != std::string::npos) {
 161     SubOpName = OpName.substr(DotIdx+1);
 162     if (SubOpName.empty())
 163       throw TheDef->getName() + ": illegal empty suboperand name in '" +Op +"'";
 164     OpName = OpName.substr(0, DotIdx);
 165   }
 166
 167   unsigned OpIdx = getOperandNamed(OpName);
 168
 169   if (SubOpName.empty()) {  // If no suboperand name was specified:
 170     // If one was needed, throw.
 171     if (OperandList[OpIdx].MINumOperands > 1 && !AllowWholeOp &&
 172         SubOpName.empty())
 173       throw TheDef->getName() + ": Illegal to refer to"
 174       " whole operand part of complex operand '" + Op + "'";
 175
 176     // Otherwise, return the operand.
 177     return std::make_pair(OpIdx, 0U);
 178   }
 179
 180   // Find the suboperand number involved.
 181   DagInit *MIOpInfo = OperandList[OpIdx].MIOperandInfo;
 182   if (MIOpInfo == 0)
 183     throw TheDef->getName() + ": unknown suboperand name in '" + Op + "'";
 184
 185   // Find the operand with the right name.
 186   for (unsigned i = 0, e = MIOpInfo->getNumArgs(); i != e; ++i)
 187     if (MIOpInfo->getArgName(i) == SubOpName)
 188       return std::make_pair(OpIdx, i);
 189
 190   // Otherwise, didn't find it!
 191   throw TheDef->getName() + ": unknown suboperand name in '" + Op + "'";
 192 }
 193
 194 static void ParseConstraint(const std::string &CStr, CGIOperandList &Ops) {
 195   // EARLY_CLOBBER: @early $reg
 196   std::string::size_type wpos = CStr.find_first_of(" \t");
 197   std::string::size_type start = CStr.find_first_not_of(" \t");
 198   std::string Tok = CStr.substr(start, wpos - start);
 199   if (Tok == "@earlyclobber") {
 200     std::string Name = CStr.substr(wpos+1);
 201     wpos = Name.find_first_not_of(" \t");
 202     if (wpos == std::string::npos)
 203       throw "Illegal format for @earlyclobber constraint: '" + CStr + "'";
 204     Name = Name.substr(wpos);
 205     std::pair<unsigned,unsigned> Op = Ops.ParseOperandName(Name, false);
 206
 207     // Build the string for the operand
 208     if (!Ops[Op.first].Constraints[Op.second].isNone())
 209       throw "Operand '" + Name + "' cannot have multiple constraints!";
 210     Ops[Op.first].Constraints[Op.second] =
 211     CGIOperandList::ConstraintInfo::getEarlyClobber();
 212     return;
 213   }
 214
 215   // Only other constraint is "TIED_TO" for now.
 216   std::string::size_type pos = CStr.find_first_of('=');
 217   assert(pos != std::string::npos && "Unrecognized constraint");
 218   start = CStr.find_first_not_of(" \t");
 219   std::string Name = CStr.substr(start, pos - start);
 220
 221   // TIED_TO: $src1 = $dst
 222   wpos = Name.find_first_of(" \t");
 223   if (wpos == std::string::npos)
 224     throw "Illegal format for tied-to constraint: '" + CStr + "'";
 225   std::string DestOpName = Name.substr(0, wpos);
 226   std::pair<unsigned,unsigned> DestOp = Ops.ParseOperandName(DestOpName, false);
 227
 228   Name = CStr.substr(pos+1);
 229   wpos = Name.find_first_not_of(" \t");
 230   if (wpos == std::string::npos)
 231     throw "Illegal format for tied-to constraint: '" + CStr + "'";
 232
 233   std::pair<unsigned,unsigned> SrcOp =
 234   Ops.ParseOperandName(Name.substr(wpos), false);
 235   if (SrcOp > DestOp)
 236     throw "Illegal tied-to operand constraint '" + CStr + "'";
 237
 238
 239   unsigned FlatOpNo = Ops.getFlattenedOperandNumber(SrcOp);
 240
 241   if (!Ops[DestOp.first].Constraints[DestOp.second].isNone())
 242     throw "Operand '" + DestOpName + "' cannot have multiple constraints!";
 243   Ops[DestOp.first].Constraints[DestOp.second] =
 244   CGIOperandList::ConstraintInfo::getTied(FlatOpNo);
 245 }
 246
 247 static void ParseConstraints(const std::string &CStr, CGIOperandList &Ops) {
 248   if (CStr.empty()) return;
 249
 250   const std::string delims(",");
 251   std::string::size_type bidx, eidx;
 252
 253   bidx = CStr.find_first_not_of(delims);
 254   while (bidx != std::string::npos) {
 255     eidx = CStr.find_first_of(delims, bidx);
 256     if (eidx == std::string::npos)
 257       eidx = CStr.length();
 258
 259     ParseConstraint(CStr.substr(bidx, eidx - bidx), Ops);
 260     bidx = CStr.find_first_not_of(delims, eidx);
 261   }
 262 }
 263
 264 void CGIOperandList::ProcessDisableEncoding(std::string DisableEncoding) {
 265   while (1) {
 266     std::string OpName;
 267     tie(OpName, DisableEncoding) = getToken(DisableEncoding, " ,\t");
 268     if (OpName.empty()) break;
 269
 270     // Figure out which operand this is.
 271     std::pair<unsigned,unsigned> Op = ParseOperandName(OpName, false);
 272
 273     // Mark the operand as not-to-be encoded.
 274     if (Op.second >= OperandList[Op.first].DoNotEncode.size())
 275       OperandList[Op.first].DoNotEncode.resize(Op.second+1);
 276     OperandList[Op.first].DoNotEncode[Op.second] = true;
 277   }
 278
 279 }
 280
 281 //===----------------------------------------------------------------------===//
 282 // CodeGenInstruction Implementation
 283 //===----------------------------------------------------------------------===//
 284
 285 CodeGenInstruction::CodeGenInstruction(Record *R) : TheDef(R), Operands(R) {
 286   Namespace = R->getValueAsString("Namespace");
 287   AsmString = R->getValueAsString("AsmString");
 288
 289   isReturn     = R->getValueAsBit("isReturn");
 290   isBranch     = R->getValueAsBit("isBranch");
 291   isIndirectBranch = R->getValueAsBit("isIndirectBranch");
 292   isCompare    = R->getValueAsBit("isCompare");
 293   isMoveImm    = R->getValueAsBit("isMoveImm");
 294   isBitcast    = R->getValueAsBit("isBitcast");
 295   isBarrier    = R->getValueAsBit("isBarrier");
 296   isCall       = R->getValueAsBit("isCall");
 297   canFoldAsLoad = R->getValueAsBit("canFoldAsLoad");
 298   mayLoad      = R->getValueAsBit("mayLoad");
 299   mayStore     = R->getValueAsBit("mayStore");
 300   isPredicable = Operands.isPredicable || R->getValueAsBit("isPredicable");
 301   isConvertibleToThreeAddress = R->getValueAsBit("isConvertibleToThreeAddress");
 302   isCommutable = R->getValueAsBit("isCommutable");
 303   isTerminator = R->getValueAsBit("isTerminator");
 304   isReMaterializable = R->getValueAsBit("isReMaterializable");
 305   hasDelaySlot = R->getValueAsBit("hasDelaySlot");
 306   usesCustomInserter = R->getValueAsBit("usesCustomInserter");
 307   hasCtrlDep   = R->getValueAsBit("hasCtrlDep");
 308   isNotDuplicable = R->getValueAsBit("isNotDuplicable");
 309   hasSideEffects = R->getValueAsBit("hasSideEffects");
 310   neverHasSideEffects = R->getValueAsBit("neverHasSideEffects");
 311   isAsCheapAsAMove = R->getValueAsBit("isAsCheapAsAMove");
 312   hasExtraSrcRegAllocReq = R->getValueAsBit("hasExtraSrcRegAllocReq");
 313   hasExtraDefRegAllocReq = R->getValueAsBit("hasExtraDefRegAllocReq");
 314   isCodeGenOnly = R->getValueAsBit("isCodeGenOnly");
 315   isPseudo = R->getValueAsBit("isPseudo");
 316   ImplicitDefs = R->getValueAsListOfDefs("Defs");
 317   ImplicitUses = R->getValueAsListOfDefs("Uses");
 318
 319   if (neverHasSideEffects + hasSideEffects > 1)
 320     throw R->getName() + ": multiple conflicting side-effect flags set!";
 321
 322   // Parse Constraints.
 323   ParseConstraints(R->getValueAsString("Constraints"), Operands);
 324
 325   // Parse the DisableEncoding field.
 326   Operands.ProcessDisableEncoding(R->getValueAsString("DisableEncoding"));
 327 }
 328
 329 /// HasOneImplicitDefWithKnownVT - If the instruction has at least one
 330 /// implicit def and it has a known VT, return the VT, otherwise return
 331 /// MVT::Other.
 332 MVT::SimpleValueType CodeGenInstruction::
 333 HasOneImplicitDefWithKnownVT(const CodeGenTarget &TargetInfo) const {
 334   if (ImplicitDefs.empty()) return MVT::Other;
 335
 336   // Check to see if the first implicit def has a resolvable type.
 337   Record *FirstImplicitDef = ImplicitDefs[0];
 338   assert(FirstImplicitDef->isSubClassOf("Register"));
 339   const std::vector<MVT::SimpleValueType> &RegVTs =
 340     TargetInfo.getRegisterVTs(FirstImplicitDef);
 341   if (RegVTs.size() == 1)
 342     return RegVTs[0];
 343   return MVT::Other;
 344 }
 345
 346
 347 /// FlattenAsmStringVariants - Flatten the specified AsmString to only
 348 /// include text from the specified variant, returning the new string.
 349 std::string CodeGenInstruction::
 350 FlattenAsmStringVariants(StringRef Cur, unsigned Variant) {
 351   std::string Res = "";
 352
 353   for (;;) {
 354     // Find the start of the next variant string.
 355     size_t VariantsStart = 0;
 356     for (size_t e = Cur.size(); VariantsStart != e; ++VariantsStart)
 357       if (Cur[VariantsStart] == '{' &&
 358           (VariantsStart == 0 || (Cur[VariantsStart-1] != '$' &&
 359                                   Cur[VariantsStart-1] != '\\')))
 360         break;
 361
 362     // Add the prefix to the result.
 363     Res += Cur.slice(0, VariantsStart);
 364     if (VariantsStart == Cur.size())
 365       break;
 366
 367     ++VariantsStart; // Skip the '{'.
 368
 369     // Scan to the end of the variants string.
 370     size_t VariantsEnd = VariantsStart;
 371     unsigned NestedBraces = 1;
 372     for (size_t e = Cur.size(); VariantsEnd != e; ++VariantsEnd) {
 373       if (Cur[VariantsEnd] == '}' && Cur[VariantsEnd-1] != '\\') {
 374         if (--NestedBraces == 0)
 375           break;
 376       } else if (Cur[VariantsEnd] == '{')
 377         ++NestedBraces;
 378     }
 379
 380     // Select the Nth variant (or empty).
 381     StringRef Selection = Cur.slice(VariantsStart, VariantsEnd);
 382     for (unsigned i = 0; i != Variant; ++i)
 383       Selection = Selection.split('|').second;
 384     Res += Selection.split('|').first;
 385
 386     assert(VariantsEnd != Cur.size() &&
 387            "Unterminated variants in assembly string!");
 388     Cur = Cur.substr(VariantsEnd + 1);
 389   }
 390
 391   return Res;
 392 }
 393
 394
 395 //===----------------------------------------------------------------------===//
 396 /// CodeGenInstAlias Implementation
 397 //===----------------------------------------------------------------------===//
 398
 399 /// tryAliasOpMatch - This is a helper function for the CodeGenInstAlias
 400 /// constructor.  It checks if an argument in an InstAlias pattern matches
 401 /// the corresponding operand of the instruction.  It returns true on a
 402 /// successful match, with ResOp set to the result operand to be used.
 403 bool CodeGenInstAlias::tryAliasOpMatch(DagInit *Result, unsigned AliasOpNo,
 404                                        Record *InstOpRec, bool hasSubOps,
 405                                        SMLoc Loc, CodeGenTarget &T,
 406                                        ResultOperand &ResOp) {
 407   Init *Arg = Result->getArg(AliasOpNo);
 408   DefInit *ADI = dynamic_cast<DefInit*>(Arg);
 409
 410   if (ADI && ADI->getDef() == InstOpRec) {
 411     // If the operand is a record, it must have a name, and the record type
 412     // must match up with the instruction's argument type.
 413     if (Result->getArgName(AliasOpNo).empty())
 414       throw TGError(Loc, "result argument #" + utostr(AliasOpNo) +
 415                     " must have a name!");
 416     ResOp = ResultOperand(Result->getArgName(AliasOpNo), ADI->getDef());
 417     return true;
 418   }
 419
 420   // Handle explicit registers.
 421   if (ADI && ADI->getDef()->isSubClassOf("Register")) {
 422     if (InstOpRec->isSubClassOf("RegisterOperand"))
 423       InstOpRec = InstOpRec->getValueAsDef("RegClass");
 424
 425     if (!InstOpRec->isSubClassOf("RegisterClass"))
 426       return false;
 427
 428     if (!T.getRegisterClass(InstOpRec)
 429         .contains(T.getRegBank().getReg(ADI->getDef())))
 430       throw TGError(Loc, "fixed register " +ADI->getDef()->getName()
 431                     + " is not a member of the " + InstOpRec->getName() +
 432                     " register class!");
 433
 434     if (!Result->getArgName(AliasOpNo).empty())
 435       throw TGError(Loc, "result fixed register argument must "
 436                     "not have a name!");
 437
 438     ResOp = ResultOperand(ADI->getDef());
 439     return true;
 440   }
 441
 442   // Handle "zero_reg" for optional def operands.
 443   if (ADI && ADI->getDef()->getName() == "zero_reg") {
 444
 445     // Check if this is an optional def.
 446     if (!InstOpRec->isSubClassOf("OptionalDefOperand"))
 447       throw TGError(Loc, "reg0 used for result that is not an "
 448                     "OptionalDefOperand!");
 449
 450     ResOp = ResultOperand(static_cast<Record*>(0));
 451     return true;
 452   }
 453
 454   if (IntInit *II = dynamic_cast<IntInit*>(Arg)) {
 455     if (hasSubOps || !InstOpRec->isSubClassOf("Operand"))
 456       return false;
 457     // Integer arguments can't have names.
 458     if (!Result->getArgName(AliasOpNo).empty())
 459       throw TGError(Loc, "result argument #" + utostr(AliasOpNo) +
 460                     " must not have a name!");
 461     ResOp = ResultOperand(II->getValue());
 462     return true;
 463   }
 464
 465   return false;
 466 }
 467
 468 CodeGenInstAlias::CodeGenInstAlias(Record *R, CodeGenTarget &T) : TheDef(R) {
 469   AsmString = R->getValueAsString("AsmString");
 470   Result = R->getValueAsDag("ResultInst");
 471
 472   // Verify that the root of the result is an instruction.
 473   DefInit *DI = dynamic_cast<DefInit*>(Result->getOperator());
 474   if (DI == 0 || !DI->getDef()->isSubClassOf("Instruction"))
 475     throw TGError(R->getLoc(), "result of inst alias should be an instruction");
 476
 477   ResultInst = &T.getInstruction(DI->getDef());
 478
 479   // NameClass - If argument names are repeated, we need to verify they have
 480   // the same class.
 481   StringMap<Record*> NameClass;
 482   for (unsigned i = 0, e = Result->getNumArgs(); i != e; ++i) {
 483     DefInit *ADI = dynamic_cast<DefInit*>(Result->getArg(i));
 484     if (!ADI || Result->getArgName(i).empty())
 485       continue;
 486     // Verify we don't have something like: (someinst GR16:$foo, GR32:$foo)
 487     // $foo can exist multiple times in the result list, but it must have the
 488     // same type.
 489     Record *&Entry = NameClass[Result->getArgName(i)];
 490     if (Entry && Entry != ADI->getDef())
 491       throw TGError(R->getLoc(), "result value $" + Result->getArgName(i) +
 492                     " is both " + Entry->getName() + " and " +
 493                     ADI->getDef()->getName() + "!");
 494     Entry = ADI->getDef();
 495   }
 496
 497   // Decode and validate the arguments of the result.
 498   unsigned AliasOpNo = 0;
 499   for (unsigned i = 0, e = ResultInst->Operands.size(); i != e; ++i) {
 500
 501     // Tied registers don't have an entry in the result dag.
 502     if (ResultInst->Operands[i].getTiedRegister() != -1)
 503       continue;
 504
 505     if (AliasOpNo >= Result->getNumArgs())
 506       throw TGError(R->getLoc(), "not enough arguments for instruction!");
 507
 508     Record *InstOpRec = ResultInst->Operands[i].Rec;
 509     unsigned NumSubOps = ResultInst->Operands[i].MINumOperands;
 510     ResultOperand ResOp(static_cast<int64_t>(0));
 511     if (tryAliasOpMatch(Result, AliasOpNo, InstOpRec, (NumSubOps > 1),
 512                         R->getLoc(), T, ResOp)) {
 513       ResultOperands.push_back(ResOp);
 514       ResultInstOperandIndex.push_back(std::make_pair(i, -1));
 515       ++AliasOpNo;
 516       continue;
 517     }
 518
 519     // If the argument did not match the instruction operand, and the operand
 520     // is composed of multiple suboperands, try matching the suboperands.
 521     if (NumSubOps > 1) {
 522       DagInit *MIOI = ResultInst->Operands[i].MIOperandInfo;
 523       for (unsigned SubOp = 0; SubOp != NumSubOps; ++SubOp) {
 524         if (AliasOpNo >= Result->getNumArgs())
 525           throw TGError(R->getLoc(), "not enough arguments for instruction!");
 526         Record *SubRec = dynamic_cast<DefInit*>(MIOI->getArg(SubOp))->getDef();
 527         if (tryAliasOpMatch(Result, AliasOpNo, SubRec, false,
 528                             R->getLoc(), T, ResOp)) {
 529           ResultOperands.push_back(ResOp);
 530           ResultInstOperandIndex.push_back(std::make_pair(i, SubOp));
 531           ++AliasOpNo;
 532         } else {
 533           throw TGError(R->getLoc(), "result argument #" + utostr(AliasOpNo) +
 534                         " does not match instruction operand class " +
 535                         (SubOp == 0 ? InstOpRec->getName() :SubRec->getName()));
 536         }
 537       }
 538       continue;
 539     }
 540     throw TGError(R->getLoc(), "result argument #" + utostr(AliasOpNo) +
 541                   " does not match instruction operand class " +
 542                   InstOpRec->getName());
 543   }
 544
 545   if (AliasOpNo != Result->getNumArgs())
 546     throw TGError(R->getLoc(), "too many operands for instruction!");
 547 }