aboutsummaryrefslogtreecommitdiffstats
path: root/utils/TableGen/CodeGenInstruction.cpp
blob: 73fe9162585a5db16f91e303c08a39c44fdc9337 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
//===- CodeGenInstruction.cpp - CodeGen Instruction Class Wrapper ---------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the CodeGenInstruction class.
//
//===----------------------------------------------------------------------===//

#include "CodeGenInstruction.h"
#include "CodeGenTarget.h"
#include "Record.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/STLExtras.h"
#include <set>
using namespace llvm;

//===----------------------------------------------------------------------===//
// CGIOperandList Implementation
//===----------------------------------------------------------------------===//

CGIOperandList::CGIOperandList(Record *R) : TheDef(R) {
  isPredicable = false;
  hasOptionalDef = false;
  isVariadic = false;

  DagInit *OutDI = R->getValueAsDag("OutOperandList");

  if (DefInit *Init = dynamic_cast<DefInit*>(OutDI->getOperator())) {
    if (Init->getDef()->getName() != "outs")
      throw R->getName() + ": invalid def name for output list: use 'outs'";
  } else
    throw R->getName() + ": invalid output list: use 'outs'";

  NumDefs = OutDI->getNumArgs();

  DagInit *InDI = R->getValueAsDag("InOperandList");
  if (DefInit *Init = dynamic_cast<DefInit*>(InDI->getOperator())) {
    if (Init->getDef()->getName() != "ins")
      throw R->getName() + ": invalid def name for input list: use 'ins'";
  } else
    throw R->getName() + ": invalid input list: use 'ins'";

  unsigned MIOperandNo = 0;
  std::set<std::string> OperandNames;
  for (unsigned i = 0, e = InDI->getNumArgs()+OutDI->getNumArgs(); i != e; ++i){
    Init *ArgInit;
    std::string ArgName;
    if (i < NumDefs) {
      ArgInit = OutDI->getArg(i);
      ArgName = OutDI->getArgName(i);
    } else {
      ArgInit = InDI->getArg(i-NumDefs);
      ArgName = InDI->getArgName(i-NumDefs);
    }

    DefInit *Arg = dynamic_cast<DefInit*>(ArgInit);
    if (!Arg)
      throw "Illegal operand for the '" + R->getName() + "' instruction!";

    Record *Rec = Arg->getDef();
    std::string PrintMethod = "printOperand";
    std::string EncoderMethod;
    unsigned NumOps = 1;
    DagInit *MIOpInfo = 0;
    if (Rec->isSubClassOf("Operand")) {
      PrintMethod = Rec->getValueAsString("PrintMethod");
      // If there is an explicit encoder method, use it.
      EncoderMethod = Rec->getValueAsString("EncoderMethod");
      MIOpInfo = Rec->getValueAsDag("MIOperandInfo");

      // Verify that MIOpInfo has an 'ops' root value.
      if (!dynamic_cast<DefInit*>(MIOpInfo->getOperator()) ||
          dynamic_cast<DefInit*>(MIOpInfo->getOperator())
          ->getDef()->getName() != "ops")
        throw "Bad value for MIOperandInfo in operand '" + Rec->getName() +
        "'\n";

      // If we have MIOpInfo, then we have #operands equal to number of entries
      // in MIOperandInfo.
      if (unsigned NumArgs = MIOpInfo->getNumArgs())
        NumOps = NumArgs;

      if (Rec->isSubClassOf("PredicateOperand"))
        isPredicable = true;
      else if (Rec->isSubClassOf("OptionalDefOperand"))
        hasOptionalDef = true;
    } else if (Rec->getName() == "variable_ops") {
      isVariadic = true;
      continue;
    } else if (!Rec->isSubClassOf("RegisterClass") &&
               !Rec->isSubClassOf("PointerLikeRegClass") &&
               Rec->getName() != "unknown")
      throw "Unknown operand class '" + Rec->getName() +
      "' in '" + R->getName() + "' instruction!";

    // Check that the operand has a name and that it's unique.
    if (ArgName.empty())
      throw "In instruction '" + R->getName() + "', operand #" + utostr(i) +
      " has no name!";
    if (!OperandNames.insert(ArgName).second)
      throw "In instruction '" + R->getName() + "', operand #" + utostr(i) +
      " has the same name as a previous operand!";

    OperandList.push_back(OperandInfo(Rec, ArgName, PrintMethod, EncoderMethod,
                                      MIOperandNo, NumOps, MIOpInfo));
    MIOperandNo += NumOps;
  }


  // Make sure the constraints list for each operand is large enough to hold
  // constraint info, even if none is present.
  for (unsigned i = 0, e = OperandList.size(); i != e; ++i)
    OperandList[i].Constraints.resize(OperandList[i].MINumOperands);
}


/// getOperandNamed - Return the index of the operand with the specified
/// non-empty name.  If the instruction does not have an operand with the
/// specified name, throw an exception.
///
unsigned CGIOperandList::getOperandNamed(StringRef Name) const {
  unsigned OpIdx;
  if (hasOperandNamed(Name, OpIdx)) return OpIdx;
  throw "'" + TheDef->getName() + "' does not have an operand named '$" +
    Name.str() + "'!";
}

/// hasOperandNamed - Query whether the instruction has an operand of the
/// given name. If so, return true and set OpIdx to the index of the
/// operand. Otherwise, return false.
bool CGIOperandList::hasOperandNamed(StringRef Name, unsigned &OpIdx) const {
  assert(!Name.empty() && "Cannot search for operand with no name!");
  for (unsigned i = 0, e = OperandList.size(); i != e; ++i)
    if (OperandList[i].Name == Name) {
      OpIdx = i;
      return true;
    }
  return false;
}

std::pair<unsigned,unsigned>
CGIOperandList::ParseOperandName(const std::string &Op, bool AllowWholeOp) {
  if (Op.empty() || Op[0] != '$')
    throw TheDef->getName() + ": Illegal operand name: '" + Op + "'";

  std::string OpName = Op.substr(1);
  std::string SubOpName;

  // Check to see if this is $foo.bar.
  std::string::size_type DotIdx = OpName.find_first_of(".");
  if (DotIdx != std::string::npos) {
    SubOpName = OpName.substr(DotIdx+1);
    if (SubOpName.empty())
      throw TheDef->getName() + ": illegal empty suboperand name in '" +Op +"'";
    OpName = OpName.substr(0, DotIdx);
  }

  unsigned OpIdx = getOperandNamed(OpName);

  if (SubOpName.empty()) {  // If no suboperand name was specified:
    // If one was needed, throw.
    if (OperandList[OpIdx].MINumOperands > 1 && !AllowWholeOp &&
        SubOpName.empty())
      throw TheDef->getName() + ": Illegal to refer to"
      " whole operand part of complex operand '" + Op + "'";

    // Otherwise, return the operand.
    return std::make_pair(OpIdx, 0U);
  }

  // Find the suboperand number involved.
  DagInit *MIOpInfo = OperandList[OpIdx].MIOperandInfo;
  if (MIOpInfo == 0)
    throw TheDef->getName() + ": unknown suboperand name in '" + Op + "'";

  // Find the operand with the right name.
  for (unsigned i = 0, e = MIOpInfo->getNumArgs(); i != e; ++i)
    if (MIOpInfo->getArgName(i) == SubOpName)
      return std::make_pair(OpIdx, i);

  // Otherwise, didn't find it!
  throw TheDef->getName() + ": unknown suboperand name in '" + Op + "'";
}

static void ParseConstraint(const std::string &CStr, CGIOperandList &Ops) {
  // EARLY_CLOBBER: @early $reg
  std::string::size_type wpos = CStr.find_first_of(" \t");
  std::string::size_type start = CStr.find_first_not_of(" \t");
  std::string Tok = CStr.substr(start, wpos - start);
  if (Tok == "@earlyclobber") {
    std::string Name = CStr.substr(wpos+1);
    wpos = Name.find_first_not_of(" \t");
    if (wpos == std::string::npos)
      throw "Illegal format for @earlyclobber constraint: '" + CStr + "'";
    Name = Name.substr(wpos);
    std::pair<unsigned,unsigned> Op = Ops.ParseOperandName(Name, false);

    // Build the string for the operand
    if (!Ops[Op.first].Constraints[Op.second].isNone())
      throw "Operand '" + Name + "' cannot have multiple constraints!";
    Ops[Op.first].Constraints[Op.second] =
    CGIOperandList::ConstraintInfo::getEarlyClobber();
    return;
  }

  // Only other constraint is "TIED_TO" for now.
  std::string::size_type pos = CStr.find_first_of('=');
  assert(pos != std::string::npos && "Unrecognized constraint");
  start = CStr.find_first_not_of(" \t");
  std::string Name = CStr.substr(start, pos - start);

  // TIED_TO: $src1 = $dst
  wpos = Name.find_first_of(" \t");
  if (wpos == std::string::npos)
    throw "Illegal format for tied-to constraint: '" + CStr + "'";
  std::string DestOpName = Name.substr(0, wpos);
  std::pair<unsigned,unsigned> DestOp = Ops.ParseOperandName(DestOpName, false);

  Name = CStr.substr(pos+1);
  wpos = Name.find_first_not_of(" \t");
  if (wpos == std::string::npos)
    throw "Illegal format for tied-to constraint: '" + CStr + "'";

  std::pair<unsigned,unsigned> SrcOp =
  Ops.ParseOperandName(Name.substr(wpos), false);
  if (SrcOp > DestOp)
    throw "Illegal tied-to operand constraint '" + CStr + "'";


  unsigned FlatOpNo = Ops.getFlattenedOperandNumber(SrcOp);

  if (!Ops[DestOp.first].Constraints[DestOp.second].isNone())
    throw "Operand '" + DestOpName + "' cannot have multiple constraints!";
  Ops[DestOp.first].Constraints[DestOp.second] =
  CGIOperandList::ConstraintInfo::getTied(FlatOpNo);
}

static void ParseConstraints(const std::string &CStr, CGIOperandList &Ops) {
  if (CStr.empty()) return;

  const std::string delims(",");
  std::string::size_type bidx, eidx;

  bidx = CStr.find_first_not_of(delims);
  while (bidx != std::string::npos) {
    eidx = CStr.find_first_of(delims, bidx);
    if (eidx == std::string::npos)
      eidx = CStr.length();

    ParseConstraint(CStr.substr(bidx, eidx - bidx), Ops);
    bidx = CStr.find_first_not_of(delims, eidx);
  }
}

void CGIOperandList::ProcessDisableEncoding(std::string DisableEncoding) {
  while (1) {
    std::string OpName;
    tie(OpName, DisableEncoding) = getToken(DisableEncoding, " ,\t");
    if (OpName.empty()) break;

    // Figure out which operand this is.
    std::pair<unsigned,unsigned> Op = ParseOperandName(OpName, false);

    // Mark the operand as not-to-be encoded.
    if (Op.second >= OperandList[Op.first].DoNotEncode.size())
      OperandList[Op.first].DoNotEncode.resize(Op.second+1);
    OperandList[Op.first].DoNotEncode[Op.second] = true;
  }

}

//===----------------------------------------------------------------------===//
// CodeGenInstruction Implementation
//===----------------------------------------------------------------------===//

CodeGenInstruction::CodeGenInstruction(Record *R) : TheDef(R), Operands(R) {
  Namespace = R->getValueAsString("Namespace");
  AsmString = R->getValueAsString("AsmString");

  isReturn     = R->getValueAsBit("isReturn");
  isBranch     = R->getValueAsBit("isBranch");
  isIndirectBranch = R->getValueAsBit("isIndirectBranch");
  isCompare    = R->getValueAsBit("isCompare");
  isMoveImm    = R->getValueAsBit("isMoveImm");
  isBitcast    = R->getValueAsBit("isBitcast");
  isBarrier    = R->getValueAsBit("isBarrier");
  isCall       = R->getValueAsBit("isCall");
  canFoldAsLoad = R->getValueAsBit("canFoldAsLoad");
  mayLoad      = R->getValueAsBit("mayLoad");
  mayStore     = R->getValueAsBit("mayStore");
  isPredicable = Operands.isPredicable || R->getValueAsBit("isPredicable");
  isConvertibleToThreeAddress = R->getValueAsBit("isConvertibleToThreeAddress");
  isCommutable = R->getValueAsBit("isCommutable");
  isTerminator = R->getValueAsBit("isTerminator");
  isReMaterializable = R->getValueAsBit("isReMaterializable");
  hasDelaySlot = R->getValueAsBit("hasDelaySlot");
  usesCustomInserter = R->getValueAsBit("usesCustomInserter");
  hasCtrlDep   = R->getValueAsBit("hasCtrlDep");
  isNotDuplicable = R->getValueAsBit("isNotDuplicable");
  hasSideEffects = R->getValueAsBit("hasSideEffects");
  neverHasSideEffects = R->getValueAsBit("neverHasSideEffects");
  isAsCheapAsAMove = R->getValueAsBit("isAsCheapAsAMove");
  hasExtraSrcRegAllocReq = R->getValueAsBit("hasExtraSrcRegAllocReq");
  hasExtraDefRegAllocReq = R->getValueAsBit("hasExtraDefRegAllocReq");
  ImplicitDefs = R->getValueAsListOfDefs("Defs");
  ImplicitUses = R->getValueAsListOfDefs("Uses");

  if (neverHasSideEffects + hasSideEffects > 1)
    throw R->getName() + ": multiple conflicting side-effect flags set!";

  // Parse Constraints.
  ParseConstraints(R->getValueAsString("Constraints"), Operands);

  // Parse the DisableEncoding field.
  Operands.ProcessDisableEncoding(R->getValueAsString("DisableEncoding"));
}

/// HasOneImplicitDefWithKnownVT - If the instruction has at least one
/// implicit def and it has a known VT, return the VT, otherwise return
/// MVT::Other.
MVT::SimpleValueType CodeGenInstruction::
HasOneImplicitDefWithKnownVT(const CodeGenTarget &TargetInfo) const {
  if (ImplicitDefs.empty()) return MVT::Other;

  // Check to see if the first implicit def has a resolvable type.
  Record *FirstImplicitDef = ImplicitDefs[0];
  assert(FirstImplicitDef->isSubClassOf("Register"));
  const std::vector<MVT::SimpleValueType> &RegVTs =
    TargetInfo.getRegisterVTs(FirstImplicitDef);
  if (RegVTs.size() == 1)
    return RegVTs[0];
  return MVT::Other;
}


/// FlattenAsmStringVariants - Flatten the specified AsmString to only
/// include text from the specified variant, returning the new string.
std::string CodeGenInstruction::
FlattenAsmStringVariants(StringRef Cur, unsigned Variant) {
  std::string Res = "";

  for (;;) {
    // Find the start of the next variant string.
    size_t VariantsStart = 0;
    for (size_t e = Cur.size(); VariantsStart != e; ++VariantsStart)
      if (Cur[VariantsStart] == '{' &&
          (VariantsStart == 0 || (Cur[VariantsStart-1] != '$' &&
                                  Cur[VariantsStart-1] != '\\')))
        break;

    // Add the prefix to the result.
    Res += Cur.slice(0, VariantsStart);
    if (VariantsStart == Cur.size())
      break;

    ++VariantsStart; // Skip the '{'.

    // Scan to the end of the variants string.
    size_t VariantsEnd = VariantsStart;
    unsigned NestedBraces = 1;
    for (size_t e = Cur.size(); VariantsEnd != e; ++VariantsEnd) {
      if (Cur[VariantsEnd] == '}' && Cur[VariantsEnd-1] != '\\') {
        if (--NestedBraces == 0)
          break;
      } else if (Cur[VariantsEnd] == '{')
        ++NestedBraces;
    }

    // Select the Nth variant (or empty).
    StringRef Selection = Cur.slice(VariantsStart, VariantsEnd);
    for (unsigned i = 0; i != Variant; ++i)
      Selection = Selection.split('|').second;
    Res += Selection.split('|').first;

    assert(VariantsEnd != Cur.size() &&
           "Unterminated variants in assembly string!");
    Cur = Cur.substr(VariantsEnd + 1);
  }

  return Res;
}


//===----------------------------------------------------------------------===//
/// CodeGenInstAlias Implementation
//===----------------------------------------------------------------------===//

/// tryAliasOpMatch - This is a helper function for the CodeGenInstAlias
/// constructor.  It checks if an argument in an InstAlias pattern matches
/// the corresponding operand of the instruction.  It returns true on a
/// successful match, with ResOp set to the result operand to be used.
bool CodeGenInstAlias::tryAliasOpMatch(DagInit *Result, unsigned AliasOpNo,
                                       Record *InstOpRec, bool hasSubOps,
                                       SMLoc Loc, CodeGenTarget &T,
                                       ResultOperand &ResOp) {
  Init *Arg = Result->getArg(AliasOpNo);
  DefInit *ADI = dynamic_cast<DefInit*>(Arg);

  if (ADI && ADI->getDef() == InstOpRec) {
    // If the operand is a record, it must have a name, and the record type
    // must match up with the instruction's argument type.
    if (Result->getArgName(AliasOpNo).empty())
      throw TGError(Loc, "result argument #" + utostr(AliasOpNo) +
                    " must have a name!");
    ResOp = ResultOperand(Result->getArgName(AliasOpNo), ADI->getDef());
    return true;
  }

  // Handle explicit registers.
  if (ADI && ADI->getDef()->isSubClassOf("Register")) {
    if (!InstOpRec->isSubClassOf("RegisterClass"))
      return false;

    if (!T.getRegisterClass(InstOpRec)
        .contains(T.getRegBank().getReg(ADI->getDef())))
      throw TGError(Loc, "fixed register " +ADI->getDef()->getName()
                    + " is not a member of the " + InstOpRec->getName() +
                    " register class!");

    if (!Result->getArgName(AliasOpNo).empty())
      throw TGError(Loc, "result fixed register argument must "
                    "not have a name!");

    ResOp = ResultOperand(ADI->getDef());
    return true;
  }

  // Handle "zero_reg" for optional def operands.
  if (ADI && ADI->getDef()->getName() == "zero_reg") {

    // Check if this is an optional def.
    if (!InstOpRec->isSubClassOf("OptionalDefOperand"))
      throw TGError(Loc, "reg0 used for result that is not an "
                    "OptionalDefOperand!");

    ResOp = ResultOperand(static_cast<Record*>(0));
    return true;
  }

  if (IntInit *II = dynamic_cast<IntInit*>(Arg)) {
    if (hasSubOps || !InstOpRec->isSubClassOf("Operand"))
      return false;
    // Integer arguments can't have names.
    if (!Result->getArgName(AliasOpNo).empty())
      throw TGError(Loc, "result argument #" + utostr(AliasOpNo) +
                    " must not have a name!");
    ResOp = ResultOperand(II->getValue());
    return true;
  }

  return false;
}

CodeGenInstAlias::CodeGenInstAlias(Record *R, CodeGenTarget &T) : TheDef(R) {
  AsmString = R->getValueAsString("AsmString");
  Result = R->getValueAsDag("ResultInst");

  // Verify that the root of the result is an instruction.
  DefInit *DI = dynamic_cast<DefInit*>(Result->getOperator());
  if (DI == 0 || !DI->getDef()->isSubClassOf("Instruction"))
    throw TGError(R->getLoc(), "result of inst alias should be an instruction");

  ResultInst = &T.getInstruction(DI->getDef());

  // NameClass - If argument names are repeated, we need to verify they have
  // the same class.
  StringMap<Record*> NameClass;
  for (unsigned i = 0, e = Result->getNumArgs(); i != e; ++i) {
    DefInit *ADI = dynamic_cast<DefInit*>(Result->getArg(i));
    if (!ADI || Result->getArgName(i).empty())
      continue;
    // Verify we don't have something like: (someinst GR16:$foo, GR32:$foo)
    // $foo can exist multiple times in the result list, but it must have the
    // same type.
    Record *&Entry = NameClass[Result->getArgName(i)];
    if (Entry && Entry != ADI->getDef())
      throw TGError(R->getLoc(), "result value $" + Result->getArgName(i) +
                    " is both " + Entry->getName() + " and " +
                    ADI->getDef()->getName() + "!");
    Entry = ADI->getDef();
  }

  // Decode and validate the arguments of the result.
  unsigned AliasOpNo = 0;
  for (unsigned i = 0, e = ResultInst->Operands.size(); i != e; ++i) {

    // Tied registers don't have an entry in the result dag.
    if (ResultInst->Operands[i].getTiedRegister() != -1)
      continue;

    if (AliasOpNo >= Result->getNumArgs())
      throw TGError(R->getLoc(), "not enough arguments for instruction!");

    Record *InstOpRec = ResultInst->Operands[i].Rec;
    unsigned NumSubOps = ResultInst->Operands[i].MINumOperands;
    ResultOperand ResOp(static_cast<int64_t>(0));
    if (tryAliasOpMatch(Result, AliasOpNo, InstOpRec, (NumSubOps > 1),
                        R->getLoc(), T, ResOp)) {
      ResultOperands.push_back(ResOp);
      ResultInstOperandIndex.push_back(std::make_pair(i, -1));
      ++AliasOpNo;
      continue;
    }

    // If the argument did not match the instruction operand, and the operand
    // is composed of multiple suboperands, try matching the suboperands.
    if (NumSubOps > 1) {
      DagInit *MIOI = ResultInst->Operands[i].MIOperandInfo;
      for (unsigned SubOp = 0; SubOp != NumSubOps; ++SubOp) {
        if (AliasOpNo >= Result->getNumArgs())
          throw TGError(R->getLoc(), "not enough arguments for instruction!");
        Record *SubRec = dynamic_cast<DefInit*>(MIOI->getArg(SubOp))->getDef();
        if (tryAliasOpMatch(Result, AliasOpNo, SubRec, false,
                            R->getLoc(), T, ResOp)) {
          ResultOperands.push_back(ResOp);
          ResultInstOperandIndex.push_back(std::make_pair(i, SubOp));
          ++AliasOpNo;
        } else {
          throw TGError(R->getLoc(), "result argument #" + utostr(AliasOpNo) +
                        " does not match instruction operand class " +
                        (SubOp == 0 ? InstOpRec->getName() :SubRec->getName()));
        }
      }
      continue;
    }
    throw TGError(R->getLoc(), "result argument #" + utostr(AliasOpNo) +
                  " does not match instruction operand class " +
                  InstOpRec->getName());
  }

  if (AliasOpNo != Result->getNumArgs())
    throw TGError(R->getLoc(), "too many operands for instruction!");
}