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      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     std::string OperandType = "OPERAND_UNKNOWN";
     71     unsigned NumOps = 1;
     72     DagInit *MIOpInfo = 0;
     73     if (Rec->isSubClassOf("RegisterOperand")) {
     74       PrintMethod = Rec->getValueAsString("PrintMethod");
     75     } else if (Rec->isSubClassOf("Operand")) {
     76       PrintMethod = Rec->getValueAsString("PrintMethod");
     77       OperandType = Rec->getValueAsString("OperandType");
     78       // If there is an explicit encoder method, use it.
     79       EncoderMethod = Rec->getValueAsString("EncoderMethod");
     80       MIOpInfo = Rec->getValueAsDag("MIOperandInfo");
     81 
     82       // Verify that MIOpInfo has an 'ops' root value.
     83       if (!dynamic_cast<DefInit*>(MIOpInfo->getOperator()) ||
     84           dynamic_cast<DefInit*>(MIOpInfo->getOperator())
     85           ->getDef()->getName() != "ops")
     86         throw "Bad value for MIOperandInfo in operand '" + Rec->getName() +
     87         "'\n";
     88 
     89       // If we have MIOpInfo, then we have #operands equal to number of entries
     90       // in MIOperandInfo.
     91       if (unsigned NumArgs = MIOpInfo->getNumArgs())
     92         NumOps = NumArgs;
     93 
     94       if (Rec->isSubClassOf("PredicateOperand"))
     95         isPredicable = true;
     96       else if (Rec->isSubClassOf("OptionalDefOperand"))
     97         hasOptionalDef = true;
     98     } else if (Rec->getName() == "variable_ops") {
     99       isVariadic = true;
    100       continue;
    101     } else if (Rec->isSubClassOf("RegisterClass")) {
    102       OperandType = "OPERAND_REGISTER";
    103     } else if (!Rec->isSubClassOf("PointerLikeRegClass") &&
    104                Rec->getName() != "unknown")
    105       throw "Unknown operand class '" + Rec->getName() +
    106       "' in '" + R->getName() + "' instruction!";
    107 
    108     // Check that the operand has a name and that it's unique.
    109     if (ArgName.empty())
    110       throw "In instruction '" + R->getName() + "', operand #" + utostr(i) +
    111       " has no name!";
    112     if (!OperandNames.insert(ArgName).second)
    113       throw "In instruction '" + R->getName() + "', operand #" + utostr(i) +
    114       " has the same name as a previous operand!";
    115 
    116     OperandList.push_back(OperandInfo(Rec, ArgName, PrintMethod, EncoderMethod,
    117                                       OperandType, MIOperandNo, NumOps,
    118                                       MIOpInfo));
    119     MIOperandNo += NumOps;
    120   }
    121 
    122 
    123   // Make sure the constraints list for each operand is large enough to hold
    124   // constraint info, even if none is present.
    125   for (unsigned i = 0, e = OperandList.size(); i != e; ++i)
    126     OperandList[i].Constraints.resize(OperandList[i].MINumOperands);
    127 }
    128 
    129 
    130 /// getOperandNamed - Return the index of the operand with the specified
    131 /// non-empty name.  If the instruction does not have an operand with the
    132 /// specified name, throw an exception.
    133 ///
    134 unsigned CGIOperandList::getOperandNamed(StringRef Name) const {
    135   unsigned OpIdx;
    136   if (hasOperandNamed(Name, OpIdx)) return OpIdx;
    137   throw "'" + TheDef->getName() + "' does not have an operand named '$" +
    138     Name.str() + "'!";
    139 }
    140 
    141 /// hasOperandNamed - Query whether the instruction has an operand of the
    142 /// given name. If so, return true and set OpIdx to the index of the
    143 /// operand. Otherwise, return false.
    144 bool CGIOperandList::hasOperandNamed(StringRef Name, unsigned &OpIdx) const {
    145   assert(!Name.empty() && "Cannot search for operand with no name!");
    146   for (unsigned i = 0, e = OperandList.size(); i != e; ++i)
    147     if (OperandList[i].Name == Name) {
    148       OpIdx = i;
    149       return true;
    150     }
    151   return false;
    152 }
    153 
    154 std::pair<unsigned,unsigned>
    155 CGIOperandList::ParseOperandName(const std::string &Op, bool AllowWholeOp) {
    156   if (Op.empty() || Op[0] != '$')
    157     throw TheDef->getName() + ": Illegal operand name: '" + Op + "'";
    158 
    159   std::string OpName = Op.substr(1);
    160   std::string SubOpName;
    161 
    162   // Check to see if this is $foo.bar.
    163   std::string::size_type DotIdx = OpName.find_first_of(".");
    164   if (DotIdx != std::string::npos) {
    165     SubOpName = OpName.substr(DotIdx+1);
    166     if (SubOpName.empty())
    167       throw TheDef->getName() + ": illegal empty suboperand name in '" +Op +"'";
    168     OpName = OpName.substr(0, DotIdx);
    169   }
    170 
    171   unsigned OpIdx = getOperandNamed(OpName);
    172 
    173   if (SubOpName.empty()) {  // If no suboperand name was specified:
    174     // If one was needed, throw.
    175     if (OperandList[OpIdx].MINumOperands > 1 && !AllowWholeOp &&
    176         SubOpName.empty())
    177       throw TheDef->getName() + ": Illegal to refer to"
    178       " whole operand part of complex operand '" + Op + "'";
    179 
    180     // Otherwise, return the operand.
    181     return std::make_pair(OpIdx, 0U);
    182   }
    183 
    184   // Find the suboperand number involved.
    185   DagInit *MIOpInfo = OperandList[OpIdx].MIOperandInfo;
    186   if (MIOpInfo == 0)
    187     throw TheDef->getName() + ": unknown suboperand name in '" + Op + "'";
    188 
    189   // Find the operand with the right name.
    190   for (unsigned i = 0, e = MIOpInfo->getNumArgs(); i != e; ++i)
    191     if (MIOpInfo->getArgName(i) == SubOpName)
    192       return std::make_pair(OpIdx, i);
    193 
    194   // Otherwise, didn't find it!
    195   throw TheDef->getName() + ": unknown suboperand name in '" + Op + "'";
    196 }
    197 
    198 static void ParseConstraint(const std::string &CStr, CGIOperandList &Ops) {
    199   // EARLY_CLOBBER: @early $reg
    200   std::string::size_type wpos = CStr.find_first_of(" \t");
    201   std::string::size_type start = CStr.find_first_not_of(" \t");
    202   std::string Tok = CStr.substr(start, wpos - start);
    203   if (Tok == "@earlyclobber") {
    204     std::string Name = CStr.substr(wpos+1);
    205     wpos = Name.find_first_not_of(" \t");
    206     if (wpos == std::string::npos)
    207       throw "Illegal format for @earlyclobber constraint: '" + CStr + "'";
    208     Name = Name.substr(wpos);
    209     std::pair<unsigned,unsigned> Op = Ops.ParseOperandName(Name, false);
    210 
    211     // Build the string for the operand
    212     if (!Ops[Op.first].Constraints[Op.second].isNone())
    213       throw "Operand '" + Name + "' cannot have multiple constraints!";
    214     Ops[Op.first].Constraints[Op.second] =
    215     CGIOperandList::ConstraintInfo::getEarlyClobber();
    216     return;
    217   }
    218 
    219   // Only other constraint is "TIED_TO" for now.
    220   std::string::size_type pos = CStr.find_first_of('=');
    221   assert(pos != std::string::npos && "Unrecognized constraint");
    222   start = CStr.find_first_not_of(" \t");
    223   std::string Name = CStr.substr(start, pos - start);
    224 
    225   // TIED_TO: $src1 = $dst
    226   wpos = Name.find_first_of(" \t");
    227   if (wpos == std::string::npos)
    228     throw "Illegal format for tied-to constraint: '" + CStr + "'";
    229   std::string DestOpName = Name.substr(0, wpos);
    230   std::pair<unsigned,unsigned> DestOp = Ops.ParseOperandName(DestOpName, false);
    231 
    232   Name = CStr.substr(pos+1);
    233   wpos = Name.find_first_not_of(" \t");
    234   if (wpos == std::string::npos)
    235     throw "Illegal format for tied-to constraint: '" + CStr + "'";
    236 
    237   std::pair<unsigned,unsigned> SrcOp =
    238   Ops.ParseOperandName(Name.substr(wpos), false);
    239   if (SrcOp > DestOp)
    240     throw "Illegal tied-to operand constraint '" + CStr + "'";
    241 
    242 
    243   unsigned FlatOpNo = Ops.getFlattenedOperandNumber(SrcOp);
    244 
    245   if (!Ops[DestOp.first].Constraints[DestOp.second].isNone())
    246     throw "Operand '" + DestOpName + "' cannot have multiple constraints!";
    247   Ops[DestOp.first].Constraints[DestOp.second] =
    248   CGIOperandList::ConstraintInfo::getTied(FlatOpNo);
    249 }
    250 
    251 static void ParseConstraints(const std::string &CStr, CGIOperandList &Ops) {
    252   if (CStr.empty()) return;
    253 
    254   const std::string delims(",");
    255   std::string::size_type bidx, eidx;
    256 
    257   bidx = CStr.find_first_not_of(delims);
    258   while (bidx != std::string::npos) {
    259     eidx = CStr.find_first_of(delims, bidx);
    260     if (eidx == std::string::npos)
    261       eidx = CStr.length();
    262 
    263     ParseConstraint(CStr.substr(bidx, eidx - bidx), Ops);
    264     bidx = CStr.find_first_not_of(delims, eidx);
    265   }
    266 }
    267 
    268 void CGIOperandList::ProcessDisableEncoding(std::string DisableEncoding) {
    269   while (1) {
    270     std::string OpName;
    271     tie(OpName, DisableEncoding) = getToken(DisableEncoding, " ,\t");
    272     if (OpName.empty()) break;
    273 
    274     // Figure out which operand this is.
    275     std::pair<unsigned,unsigned> Op = ParseOperandName(OpName, false);
    276 
    277     // Mark the operand as not-to-be encoded.
    278     if (Op.second >= OperandList[Op.first].DoNotEncode.size())
    279       OperandList[Op.first].DoNotEncode.resize(Op.second+1);
    280     OperandList[Op.first].DoNotEncode[Op.second] = true;
    281   }
    282 
    283 }
    284 
    285 //===----------------------------------------------------------------------===//
    286 // CodeGenInstruction Implementation
    287 //===----------------------------------------------------------------------===//
    288 
    289 CodeGenInstruction::CodeGenInstruction(Record *R) : TheDef(R), Operands(R) {
    290   Namespace = R->getValueAsString("Namespace");
    291   AsmString = R->getValueAsString("AsmString");
    292 
    293   isReturn     = R->getValueAsBit("isReturn");
    294   isBranch     = R->getValueAsBit("isBranch");
    295   isIndirectBranch = R->getValueAsBit("isIndirectBranch");
    296   isCompare    = R->getValueAsBit("isCompare");
    297   isMoveImm    = R->getValueAsBit("isMoveImm");
    298   isBitcast    = R->getValueAsBit("isBitcast");
    299   isBarrier    = R->getValueAsBit("isBarrier");
    300   isCall       = R->getValueAsBit("isCall");
    301   canFoldAsLoad = R->getValueAsBit("canFoldAsLoad");
    302   mayLoad      = R->getValueAsBit("mayLoad");
    303   mayStore     = R->getValueAsBit("mayStore");
    304   isPredicable = Operands.isPredicable || R->getValueAsBit("isPredicable");
    305   isConvertibleToThreeAddress = R->getValueAsBit("isConvertibleToThreeAddress");
    306   isCommutable = R->getValueAsBit("isCommutable");
    307   isTerminator = R->getValueAsBit("isTerminator");
    308   isReMaterializable = R->getValueAsBit("isReMaterializable");
    309   hasDelaySlot = R->getValueAsBit("hasDelaySlot");
    310   usesCustomInserter = R->getValueAsBit("usesCustomInserter");
    311   hasCtrlDep   = R->getValueAsBit("hasCtrlDep");
    312   isNotDuplicable = R->getValueAsBit("isNotDuplicable");
    313   hasSideEffects = R->getValueAsBit("hasSideEffects");
    314   neverHasSideEffects = R->getValueAsBit("neverHasSideEffects");
    315   isAsCheapAsAMove = R->getValueAsBit("isAsCheapAsAMove");
    316   hasExtraSrcRegAllocReq = R->getValueAsBit("hasExtraSrcRegAllocReq");
    317   hasExtraDefRegAllocReq = R->getValueAsBit("hasExtraDefRegAllocReq");
    318   isCodeGenOnly = R->getValueAsBit("isCodeGenOnly");
    319   isPseudo = R->getValueAsBit("isPseudo");
    320   ImplicitDefs = R->getValueAsListOfDefs("Defs");
    321   ImplicitUses = R->getValueAsListOfDefs("Uses");
    322 
    323   if (neverHasSideEffects + hasSideEffects > 1)
    324     throw R->getName() + ": multiple conflicting side-effect flags set!";
    325 
    326   // Parse Constraints.
    327   ParseConstraints(R->getValueAsString("Constraints"), Operands);
    328 
    329   // Parse the DisableEncoding field.
    330   Operands.ProcessDisableEncoding(R->getValueAsString("DisableEncoding"));
    331 }
    332 
    333 /// HasOneImplicitDefWithKnownVT - If the instruction has at least one
    334 /// implicit def and it has a known VT, return the VT, otherwise return
    335 /// MVT::Other.
    336 MVT::SimpleValueType CodeGenInstruction::
    337 HasOneImplicitDefWithKnownVT(const CodeGenTarget &TargetInfo) const {
    338   if (ImplicitDefs.empty()) return MVT::Other;
    339 
    340   // Check to see if the first implicit def has a resolvable type.
    341   Record *FirstImplicitDef = ImplicitDefs[0];
    342   assert(FirstImplicitDef->isSubClassOf("Register"));
    343   const std::vector<MVT::SimpleValueType> &RegVTs =
    344     TargetInfo.getRegisterVTs(FirstImplicitDef);
    345   if (RegVTs.size() == 1)
    346     return RegVTs[0];
    347   return MVT::Other;
    348 }
    349 
    350 
    351 /// FlattenAsmStringVariants - Flatten the specified AsmString to only
    352 /// include text from the specified variant, returning the new string.
    353 std::string CodeGenInstruction::
    354 FlattenAsmStringVariants(StringRef Cur, unsigned Variant) {
    355   std::string Res = "";
    356 
    357   for (;;) {
    358     // Find the start of the next variant string.
    359     size_t VariantsStart = 0;
    360     for (size_t e = Cur.size(); VariantsStart != e; ++VariantsStart)
    361       if (Cur[VariantsStart] == '{' &&
    362           (VariantsStart == 0 || (Cur[VariantsStart-1] != '$' &&
    363                                   Cur[VariantsStart-1] != '\\')))
    364         break;
    365 
    366     // Add the prefix to the result.
    367     Res += Cur.slice(0, VariantsStart);
    368     if (VariantsStart == Cur.size())
    369       break;
    370 
    371     ++VariantsStart; // Skip the '{'.
    372 
    373     // Scan to the end of the variants string.
    374     size_t VariantsEnd = VariantsStart;
    375     unsigned NestedBraces = 1;
    376     for (size_t e = Cur.size(); VariantsEnd != e; ++VariantsEnd) {
    377       if (Cur[VariantsEnd] == '}' && Cur[VariantsEnd-1] != '\\') {
    378         if (--NestedBraces == 0)
    379           break;
    380       } else if (Cur[VariantsEnd] == '{')
    381         ++NestedBraces;
    382     }
    383 
    384     // Select the Nth variant (or empty).
    385     StringRef Selection = Cur.slice(VariantsStart, VariantsEnd);
    386     for (unsigned i = 0; i != Variant; ++i)
    387       Selection = Selection.split('|').second;
    388     Res += Selection.split('|').first;
    389 
    390     assert(VariantsEnd != Cur.size() &&
    391            "Unterminated variants in assembly string!");
    392     Cur = Cur.substr(VariantsEnd + 1);
    393   }
    394 
    395   return Res;
    396 }
    397 
    398 
    399 //===----------------------------------------------------------------------===//
    400 /// CodeGenInstAlias Implementation
    401 //===----------------------------------------------------------------------===//
    402 
    403 /// tryAliasOpMatch - This is a helper function for the CodeGenInstAlias
    404 /// constructor.  It checks if an argument in an InstAlias pattern matches
    405 /// the corresponding operand of the instruction.  It returns true on a
    406 /// successful match, with ResOp set to the result operand to be used.
    407 bool CodeGenInstAlias::tryAliasOpMatch(DagInit *Result, unsigned AliasOpNo,
    408                                        Record *InstOpRec, bool hasSubOps,
    409                                        SMLoc Loc, CodeGenTarget &T,
    410                                        ResultOperand &ResOp) {
    411   Init *Arg = Result->getArg(AliasOpNo);
    412   DefInit *ADI = dynamic_cast<DefInit*>(Arg);
    413 
    414   if (ADI && ADI->getDef() == InstOpRec) {
    415     // If the operand is a record, it must have a name, and the record type
    416     // must match up with the instruction's argument type.
    417     if (Result->getArgName(AliasOpNo).empty())
    418       throw TGError(Loc, "result argument #" + utostr(AliasOpNo) +
    419                     " must have a name!");
    420     ResOp = ResultOperand(Result->getArgName(AliasOpNo), ADI->getDef());
    421     return true;
    422   }
    423 
    424   // Handle explicit registers.
    425   if (ADI && ADI->getDef()->isSubClassOf("Register")) {
    426     if (InstOpRec->isSubClassOf("RegisterOperand"))
    427       InstOpRec = InstOpRec->getValueAsDef("RegClass");
    428 
    429     if (!InstOpRec->isSubClassOf("RegisterClass"))
    430       return false;
    431 
    432     if (!T.getRegisterClass(InstOpRec)
    433         .contains(T.getRegBank().getReg(ADI->getDef())))
    434       throw TGError(Loc, "fixed register " +ADI->getDef()->getName()
    435                     + " is not a member of the " + InstOpRec->getName() +
    436                     " register class!");
    437 
    438     if (!Result->getArgName(AliasOpNo).empty())
    439       throw TGError(Loc, "result fixed register argument must "
    440                     "not have a name!");
    441 
    442     ResOp = ResultOperand(ADI->getDef());
    443     return true;
    444   }
    445 
    446   // Handle "zero_reg" for optional def operands.
    447   if (ADI && ADI->getDef()->getName() == "zero_reg") {
    448 
    449     // Check if this is an optional def.
    450     if (!InstOpRec->isSubClassOf("OptionalDefOperand"))
    451       throw TGError(Loc, "reg0 used for result that is not an "
    452                     "OptionalDefOperand!");
    453 
    454     ResOp = ResultOperand(static_cast<Record*>(0));
    455     return true;
    456   }
    457 
    458   if (IntInit *II = dynamic_cast<IntInit*>(Arg)) {
    459     if (hasSubOps || !InstOpRec->isSubClassOf("Operand"))
    460       return false;
    461     // Integer arguments can't have names.
    462     if (!Result->getArgName(AliasOpNo).empty())
    463       throw TGError(Loc, "result argument #" + utostr(AliasOpNo) +
    464                     " must not have a name!");
    465     ResOp = ResultOperand(II->getValue());
    466     return true;
    467   }
    468 
    469   return false;
    470 }
    471 
    472 CodeGenInstAlias::CodeGenInstAlias(Record *R, CodeGenTarget &T) : TheDef(R) {
    473   AsmString = R->getValueAsString("AsmString");
    474   Result = R->getValueAsDag("ResultInst");
    475 
    476   // Verify that the root of the result is an instruction.
    477   DefInit *DI = dynamic_cast<DefInit*>(Result->getOperator());
    478   if (DI == 0 || !DI->getDef()->isSubClassOf("Instruction"))
    479     throw TGError(R->getLoc(), "result of inst alias should be an instruction");
    480 
    481   ResultInst = &T.getInstruction(DI->getDef());
    482 
    483   // NameClass - If argument names are repeated, we need to verify they have
    484   // the same class.
    485   StringMap<Record*> NameClass;
    486   for (unsigned i = 0, e = Result->getNumArgs(); i != e; ++i) {
    487     DefInit *ADI = dynamic_cast<DefInit*>(Result->getArg(i));
    488     if (!ADI || Result->getArgName(i).empty())
    489       continue;
    490     // Verify we don't have something like: (someinst GR16:$foo, GR32:$foo)
    491     // $foo can exist multiple times in the result list, but it must have the
    492     // same type.
    493     Record *&Entry = NameClass[Result->getArgName(i)];
    494     if (Entry && Entry != ADI->getDef())
    495       throw TGError(R->getLoc(), "result value $" + Result->getArgName(i) +
    496                     " is both " + Entry->getName() + " and " +
    497                     ADI->getDef()->getName() + "!");
    498     Entry = ADI->getDef();
    499   }
    500 
    501   // Decode and validate the arguments of the result.
    502   unsigned AliasOpNo = 0;
    503   for (unsigned i = 0, e = ResultInst->Operands.size(); i != e; ++i) {
    504 
    505     // Tied registers don't have an entry in the result dag.
    506     if (ResultInst->Operands[i].getTiedRegister() != -1)
    507       continue;
    508 
    509     if (AliasOpNo >= Result->getNumArgs())
    510       throw TGError(R->getLoc(), "not enough arguments for instruction!");
    511 
    512     Record *InstOpRec = ResultInst->Operands[i].Rec;
    513     unsigned NumSubOps = ResultInst->Operands[i].MINumOperands;
    514     ResultOperand ResOp(static_cast<int64_t>(0));
    515     if (tryAliasOpMatch(Result, AliasOpNo, InstOpRec, (NumSubOps > 1),
    516                         R->getLoc(), T, ResOp)) {
    517       ResultOperands.push_back(ResOp);
    518       ResultInstOperandIndex.push_back(std::make_pair(i, -1));
    519       ++AliasOpNo;
    520       continue;
    521     }
    522 
    523     // If the argument did not match the instruction operand, and the operand
    524     // is composed of multiple suboperands, try matching the suboperands.
    525     if (NumSubOps > 1) {
    526       DagInit *MIOI = ResultInst->Operands[i].MIOperandInfo;
    527       for (unsigned SubOp = 0; SubOp != NumSubOps; ++SubOp) {
    528         if (AliasOpNo >= Result->getNumArgs())
    529           throw TGError(R->getLoc(), "not enough arguments for instruction!");
    530         Record *SubRec = dynamic_cast<DefInit*>(MIOI->getArg(SubOp))->getDef();
    531         if (tryAliasOpMatch(Result, AliasOpNo, SubRec, false,
    532                             R->getLoc(), T, ResOp)) {
    533           ResultOperands.push_back(ResOp);
    534           ResultInstOperandIndex.push_back(std::make_pair(i, SubOp));
    535           ++AliasOpNo;
    536         } else {
    537           throw TGError(R->getLoc(), "result argument #" + utostr(AliasOpNo) +
    538                         " does not match instruction operand class " +
    539                         (SubOp == 0 ? InstOpRec->getName() :SubRec->getName()));
    540         }
    541       }
    542       continue;
    543     }
    544     throw TGError(R->getLoc(), "result argument #" + utostr(AliasOpNo) +
    545                   " does not match instruction operand class " +
    546                   InstOpRec->getName());
    547   }
    548 
    549   if (AliasOpNo != Result->getNumArgs())
    550     throw TGError(R->getLoc(), "too many operands for instruction!");
    551 }
    552