aboutsummaryrefslogtreecommitdiffstats
path: root/contrib/libs/llvm12/lib/MC/MCParser/AsmLexer.cpp
blob: 1fa22ab000f08cba00a06cc99e6bd7ebba7a4894 (plain) (blame)
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
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
//===- AsmLexer.cpp - Lexer for Assembly Files ----------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This class implements the lexer for assembly files.
//
//===----------------------------------------------------------------------===//

#include "llvm/MC/MCParser/AsmLexer.h"
#include "llvm/ADT/APInt.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/StringSwitch.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCParser/MCAsmLexer.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/SMLoc.h"
#include "llvm/Support/SaveAndRestore.h"
#include <cassert>
#include <cctype>
#include <cstdio>
#include <cstring>
#include <string>
#include <tuple>
#include <utility>

using namespace llvm;

AsmLexer::AsmLexer(const MCAsmInfo &MAI) : MAI(MAI) {
  AllowAtInIdentifier = !StringRef(MAI.getCommentString()).startswith("@");
}

AsmLexer::~AsmLexer() = default;

void AsmLexer::setBuffer(StringRef Buf, const char *ptr,
                         bool EndStatementAtEOF) {
  CurBuf = Buf;

  if (ptr)
    CurPtr = ptr;
  else
    CurPtr = CurBuf.begin();

  TokStart = nullptr;
  this->EndStatementAtEOF = EndStatementAtEOF;
}

/// ReturnError - Set the error to the specified string at the specified
/// location.  This is defined to always return AsmToken::Error.
AsmToken AsmLexer::ReturnError(const char *Loc, const std::string &Msg) {
  SetError(SMLoc::getFromPointer(Loc), Msg);

  return AsmToken(AsmToken::Error, StringRef(Loc, CurPtr - Loc));
}

int AsmLexer::getNextChar() {
  if (CurPtr == CurBuf.end())
    return EOF;
  return (unsigned char)*CurPtr++;
}

int AsmLexer::peekNextChar() {
  if (CurPtr == CurBuf.end())
    return EOF;
  return (unsigned char)*CurPtr;
}

/// The leading integral digit sequence and dot should have already been
/// consumed, some or all of the fractional digit sequence *can* have been
/// consumed.
AsmToken AsmLexer::LexFloatLiteral() {
  // Skip the fractional digit sequence.
  while (isDigit(*CurPtr))
    ++CurPtr;

  if (*CurPtr == '-' || *CurPtr == '+')
    return ReturnError(CurPtr, "Invalid sign in float literal");

  // Check for exponent
  if ((*CurPtr == 'e' || *CurPtr == 'E')) {
    ++CurPtr;

    if (*CurPtr == '-' || *CurPtr == '+')
      ++CurPtr;

    while (isDigit(*CurPtr))
      ++CurPtr;
  }

  return AsmToken(AsmToken::Real,
                  StringRef(TokStart, CurPtr - TokStart));
}

/// LexHexFloatLiteral matches essentially (.[0-9a-fA-F]*)?[pP][+-]?[0-9a-fA-F]+
/// while making sure there are enough actual digits around for the constant to
/// be valid.
///
/// The leading "0x[0-9a-fA-F]*" (i.e. integer part) has already been consumed
/// before we get here.
AsmToken AsmLexer::LexHexFloatLiteral(bool NoIntDigits) {
  assert((*CurPtr == 'p' || *CurPtr == 'P' || *CurPtr == '.') &&
         "unexpected parse state in floating hex");
  bool NoFracDigits = true;

  // Skip the fractional part if there is one
  if (*CurPtr == '.') {
    ++CurPtr;

    const char *FracStart = CurPtr;
    while (isHexDigit(*CurPtr))
      ++CurPtr;

    NoFracDigits = CurPtr == FracStart;
  }

  if (NoIntDigits && NoFracDigits)
    return ReturnError(TokStart, "invalid hexadecimal floating-point constant: "
                                 "expected at least one significand digit");

  // Make sure we do have some kind of proper exponent part
  if (*CurPtr != 'p' && *CurPtr != 'P')
    return ReturnError(TokStart, "invalid hexadecimal floating-point constant: "
                                 "expected exponent part 'p'");
  ++CurPtr;

  if (*CurPtr == '+' || *CurPtr == '-')
    ++CurPtr;

  // N.b. exponent digits are *not* hex
  const char *ExpStart = CurPtr;
  while (isDigit(*CurPtr))
    ++CurPtr;

  if (CurPtr == ExpStart)
    return ReturnError(TokStart, "invalid hexadecimal floating-point constant: "
                                 "expected at least one exponent digit");

  return AsmToken(AsmToken::Real, StringRef(TokStart, CurPtr - TokStart));
}

/// LexIdentifier: [a-zA-Z_.][a-zA-Z0-9_$.@?]*
static bool IsIdentifierChar(char c, bool AllowAt) {
  return isAlnum(c) || c == '_' || c == '$' || c == '.' ||
         (c == '@' && AllowAt) || c == '?';
}

AsmToken AsmLexer::LexIdentifier() {
  // Check for floating point literals.
  if (CurPtr[-1] == '.' && isDigit(*CurPtr)) {
    // Disambiguate a .1243foo identifier from a floating literal.
    while (isDigit(*CurPtr))
      ++CurPtr;

    if (!IsIdentifierChar(*CurPtr, AllowAtInIdentifier) ||
        *CurPtr == 'e' || *CurPtr == 'E')
      return LexFloatLiteral();
  }

  while (IsIdentifierChar(*CurPtr, AllowAtInIdentifier))
    ++CurPtr;

  // Handle . as a special case.
  if (CurPtr == TokStart+1 && TokStart[0] == '.')
    return AsmToken(AsmToken::Dot, StringRef(TokStart, 1));

  return AsmToken(AsmToken::Identifier, StringRef(TokStart, CurPtr - TokStart));
}

/// LexSlash: Slash: /
///           C-Style Comment: /* ... */
AsmToken AsmLexer::LexSlash() {
  switch (*CurPtr) {
  case '*':
    IsAtStartOfStatement = false;
    break; // C style comment.
  case '/':
    ++CurPtr;
    return LexLineComment();
  default:
    IsAtStartOfStatement = false;
    return AsmToken(AsmToken::Slash, StringRef(TokStart, 1));
  }

  // C Style comment.
  ++CurPtr;  // skip the star.
  const char *CommentTextStart = CurPtr;
  while (CurPtr != CurBuf.end()) {
    switch (*CurPtr++) {
    case '*':
      // End of the comment?
      if (*CurPtr != '/')
        break;
      // If we have a CommentConsumer, notify it about the comment.
      if (CommentConsumer) {
        CommentConsumer->HandleComment(
            SMLoc::getFromPointer(CommentTextStart),
            StringRef(CommentTextStart, CurPtr - 1 - CommentTextStart));
      }
      ++CurPtr;   // End the */.
      return AsmToken(AsmToken::Comment,
                      StringRef(TokStart, CurPtr - TokStart));
    }
  }
  return ReturnError(TokStart, "unterminated comment");
}

/// LexLineComment: Comment: #[^\n]*
///                        : //[^\n]*
AsmToken AsmLexer::LexLineComment() {
  // Mark This as an end of statement with a body of the
  // comment. While it would be nicer to leave this two tokens,
  // backwards compatability with TargetParsers makes keeping this in this form
  // better.
  const char *CommentTextStart = CurPtr;
  int CurChar = getNextChar();
  while (CurChar != '\n' && CurChar != '\r' && CurChar != EOF)
    CurChar = getNextChar();
  if (CurChar == '\r' && CurPtr != CurBuf.end() && *CurPtr == '\n')
    ++CurPtr;

  // If we have a CommentConsumer, notify it about the comment.
  if (CommentConsumer) {
    CommentConsumer->HandleComment(
        SMLoc::getFromPointer(CommentTextStart),
        StringRef(CommentTextStart, CurPtr - 1 - CommentTextStart));
  }

  IsAtStartOfLine = true;
  // This is a whole line comment. leave newline
  if (IsAtStartOfStatement)
    return AsmToken(AsmToken::EndOfStatement,
                    StringRef(TokStart, CurPtr - TokStart));
  IsAtStartOfStatement = true;

  return AsmToken(AsmToken::EndOfStatement,
                  StringRef(TokStart, CurPtr - 1 - TokStart));
}

static void SkipIgnoredIntegerSuffix(const char *&CurPtr) {
  // Skip ULL, UL, U, L and LL suffices.
  if (CurPtr[0] == 'U')
    ++CurPtr;
  if (CurPtr[0] == 'L')
    ++CurPtr;
  if (CurPtr[0] == 'L')
    ++CurPtr;
}

// Look ahead to search for first non-hex digit, if it's [hH], then we treat the
// integer as a hexadecimal, possibly with leading zeroes.
static unsigned doHexLookAhead(const char *&CurPtr, unsigned DefaultRadix,
                               bool LexHex) {
  const char *FirstNonDec = nullptr;
  const char *LookAhead = CurPtr;
  while (true) {
    if (isDigit(*LookAhead)) {
      ++LookAhead;
    } else {
      if (!FirstNonDec)
        FirstNonDec = LookAhead;

      // Keep going if we are looking for a 'h' suffix.
      if (LexHex && isHexDigit(*LookAhead))
        ++LookAhead;
      else
        break;
    }
  }
  bool isHex = LexHex && (*LookAhead == 'h' || *LookAhead == 'H');
  CurPtr = isHex || !FirstNonDec ? LookAhead : FirstNonDec;
  if (isHex)
    return 16;
  return DefaultRadix;
}

static const char *findLastDigit(const char *CurPtr, unsigned DefaultRadix) {
  while (hexDigitValue(*CurPtr) < DefaultRadix) {
    ++CurPtr;
  }
  return CurPtr;
}

static AsmToken intToken(StringRef Ref, APInt &Value) {
  if (Value.isIntN(64))
    return AsmToken(AsmToken::Integer, Ref, Value);
  return AsmToken(AsmToken::BigNum, Ref, Value);
}

static std::string radixName(unsigned Radix) {
  switch (Radix) {
  case 2:
    return "binary";
  case 8:
    return "octal";
  case 10:
    return "decimal";
  case 16:
    return "hexadecimal";
  default:
    return "base-" + std::to_string(Radix);
  }
}

/// LexDigit: First character is [0-9].
///   Local Label: [0-9][:]
///   Forward/Backward Label: [0-9][fb]
///   Binary integer: 0b[01]+
///   Octal integer: 0[0-7]+
///   Hex integer: 0x[0-9a-fA-F]+ or [0x]?[0-9][0-9a-fA-F]*[hH]
///   Decimal integer: [1-9][0-9]*
AsmToken AsmLexer::LexDigit() {
  // MASM-flavor binary integer: [01]+[yY] (if DefaultRadix < 16, [bByY])
  // MASM-flavor octal integer: [0-7]+[oOqQ]
  // MASM-flavor decimal integer: [0-9]+[tT] (if DefaultRadix < 16, [dDtT])
  // MASM-flavor hexadecimal integer: [0-9][0-9a-fA-F]*[hH]
  if (LexMasmIntegers && isdigit(CurPtr[-1])) {
    const char *FirstNonBinary =
        (CurPtr[-1] != '0' && CurPtr[-1] != '1') ? CurPtr - 1 : nullptr;
    const char *FirstNonDecimal =
        (CurPtr[-1] < '0' || CurPtr[-1] > '9') ? CurPtr - 1 : nullptr;
    const char *OldCurPtr = CurPtr;
    while (isHexDigit(*CurPtr)) {
      switch (*CurPtr) {
      default:
        if (!FirstNonDecimal) {
          FirstNonDecimal = CurPtr;
        }
        LLVM_FALLTHROUGH;
      case '9':
      case '8':
      case '7':
      case '6':
      case '5':
      case '4':
      case '3':
      case '2':
        if (!FirstNonBinary) {
          FirstNonBinary = CurPtr;
        }
        break;
      case '1':
      case '0':
        break;
      }
      ++CurPtr;
    }
    if (*CurPtr == '.') {
      // MASM float literals (other than hex floats) always contain a ".", and
      // are always written in decimal.
      ++CurPtr;
      return LexFloatLiteral();
    }

    if (LexMasmHexFloats && (*CurPtr == 'r' || *CurPtr == 'R')) {
      ++CurPtr;
      return AsmToken(AsmToken::Real, StringRef(TokStart, CurPtr - TokStart));
    }

    unsigned Radix = 0;
    if (*CurPtr == 'h' || *CurPtr == 'H') {
      // hexadecimal number
      ++CurPtr;
      Radix = 16;
    } else if (*CurPtr == 't' || *CurPtr == 'T') {
      // decimal number
      ++CurPtr;
      Radix = 10;
    } else if (*CurPtr == 'o' || *CurPtr == 'O' || *CurPtr == 'q' ||
               *CurPtr == 'Q') {
      // octal number
      ++CurPtr;
      Radix = 8;
    } else if (*CurPtr == 'y' || *CurPtr == 'Y') {
      // binary number
      ++CurPtr;
      Radix = 2;
    } else if (FirstNonDecimal && FirstNonDecimal + 1 == CurPtr &&
               DefaultRadix < 14 &&
               (*FirstNonDecimal == 'd' || *FirstNonDecimal == 'D')) {
      Radix = 10;
    } else if (FirstNonBinary && FirstNonBinary + 1 == CurPtr &&
               DefaultRadix < 12 &&
               (*FirstNonBinary == 'b' || *FirstNonBinary == 'B')) {
      Radix = 2;
    }

    if (Radix) {
      StringRef Result(TokStart, CurPtr - TokStart);
      APInt Value(128, 0, true);

      if (Result.drop_back().getAsInteger(Radix, Value))
        return ReturnError(TokStart, "invalid " + radixName(Radix) + " number");

      // MSVC accepts and ignores type suffices on integer literals.
      SkipIgnoredIntegerSuffix(CurPtr);

      return intToken(Result, Value);
    }

    // default-radix integers, or floating point numbers, fall through
    CurPtr = OldCurPtr;
  }

  // MASM default-radix integers: [0-9a-fA-F]+
  // (All other integer literals have a radix specifier.)
  if (LexMasmIntegers && UseMasmDefaultRadix) {
    CurPtr = findLastDigit(CurPtr, 16);
    StringRef Result(TokStart, CurPtr - TokStart);

    APInt Value(128, 0, true);
    if (Result.getAsInteger(DefaultRadix, Value)) {
      return ReturnError(TokStart,
                         "invalid " + radixName(DefaultRadix) + " number");
    }

    return intToken(Result, Value);
  }

  // Decimal integer: [1-9][0-9]*
  if (CurPtr[-1] != '0' || CurPtr[0] == '.') {
    unsigned Radix = doHexLookAhead(CurPtr, 10, LexMasmIntegers);
    bool isHex = Radix == 16;
    // Check for floating point literals.
    if (!isHex && (*CurPtr == '.' || *CurPtr == 'e' || *CurPtr == 'E')) {
      if (*CurPtr == '.')
        ++CurPtr;
      return LexFloatLiteral();
    }

    StringRef Result(TokStart, CurPtr - TokStart);

    APInt Value(128, 0, true);
    if (Result.getAsInteger(Radix, Value)) {
      return ReturnError(TokStart, "invalid " + radixName(Radix) + " number");
    }

    // The darwin/x86 (and x86-64) assembler accepts and ignores type
    // suffices on integer literals.
    SkipIgnoredIntegerSuffix(CurPtr);

    return intToken(Result, Value);
  }

  if (!LexMasmIntegers && ((*CurPtr == 'b') || (*CurPtr == 'B'))) {
    ++CurPtr;
    // See if we actually have "0b" as part of something like "jmp 0b\n"
    if (!isDigit(CurPtr[0])) {
      --CurPtr;
      StringRef Result(TokStart, CurPtr - TokStart);
      return AsmToken(AsmToken::Integer, Result, 0);
    }
    const char *NumStart = CurPtr;
    while (CurPtr[0] == '0' || CurPtr[0] == '1')
      ++CurPtr;

    // Requires at least one binary digit.
    if (CurPtr == NumStart)
      return ReturnError(TokStart, "invalid binary number");

    StringRef Result(TokStart, CurPtr - TokStart);

    APInt Value(128, 0, true);
    if (Result.substr(2).getAsInteger(2, Value))
      return ReturnError(TokStart, "invalid binary number");

    // The darwin/x86 (and x86-64) assembler accepts and ignores ULL and LL
    // suffixes on integer literals.
    SkipIgnoredIntegerSuffix(CurPtr);

    return intToken(Result, Value);
  }

  if ((*CurPtr == 'x') || (*CurPtr == 'X')) {
    ++CurPtr;
    const char *NumStart = CurPtr;
    while (isHexDigit(CurPtr[0]))
      ++CurPtr;

    // "0x.0p0" is valid, and "0x0p0" (but not "0xp0" for example, which will be
    // diagnosed by LexHexFloatLiteral).
    if (CurPtr[0] == '.' || CurPtr[0] == 'p' || CurPtr[0] == 'P')
      return LexHexFloatLiteral(NumStart == CurPtr);

    // Otherwise requires at least one hex digit.
    if (CurPtr == NumStart)
      return ReturnError(CurPtr-2, "invalid hexadecimal number");

    APInt Result(128, 0);
    if (StringRef(TokStart, CurPtr - TokStart).getAsInteger(0, Result))
      return ReturnError(TokStart, "invalid hexadecimal number");

    // Consume the optional [hH].
    if (LexMasmIntegers && (*CurPtr == 'h' || *CurPtr == 'H'))
      ++CurPtr;

    // The darwin/x86 (and x86-64) assembler accepts and ignores ULL and LL
    // suffixes on integer literals.
    SkipIgnoredIntegerSuffix(CurPtr);

    return intToken(StringRef(TokStart, CurPtr - TokStart), Result);
  }

  // Either octal or hexadecimal.
  APInt Value(128, 0, true);
  unsigned Radix = doHexLookAhead(CurPtr, 8, LexMasmIntegers);
  StringRef Result(TokStart, CurPtr - TokStart);
  if (Result.getAsInteger(Radix, Value))
    return ReturnError(TokStart, "invalid " + radixName(Radix) + " number");

  // Consume the [hH].
  if (Radix == 16)
    ++CurPtr;

  // The darwin/x86 (and x86-64) assembler accepts and ignores ULL and LL
  // suffixes on integer literals.
  SkipIgnoredIntegerSuffix(CurPtr);

  return intToken(Result, Value);
}

/// LexSingleQuote: Integer: 'b'
AsmToken AsmLexer::LexSingleQuote() {
  int CurChar = getNextChar();

  if (LexMasmStrings) {
    while (CurChar != EOF) {
      if (CurChar != '\'') {
        CurChar = getNextChar();
      } else if (peekNextChar() == '\'') {
        // In MASM single-quote strings, doubled single-quotes mean an escaped
        // single quote, so should be lexed in.
        getNextChar();
        CurChar = getNextChar();
      } else {
        break;
      }
    }
    if (CurChar == EOF)
      return ReturnError(TokStart, "unterminated string constant");
    return AsmToken(AsmToken::String, StringRef(TokStart, CurPtr - TokStart));
  }

  if (CurChar == '\\')
    CurChar = getNextChar();

  if (CurChar == EOF)
    return ReturnError(TokStart, "unterminated single quote");

  CurChar = getNextChar();

  if (CurChar != '\'')
    return ReturnError(TokStart, "single quote way too long");

  // The idea here being that 'c' is basically just an integral
  // constant.
  StringRef Res = StringRef(TokStart,CurPtr - TokStart);
  long long Value;

  if (Res.startswith("\'\\")) {
    char theChar = Res[2];
    switch (theChar) {
      default: Value = theChar; break;
      case '\'': Value = '\''; break;
      case 't': Value = '\t'; break;
      case 'n': Value = '\n'; break;
      case 'b': Value = '\b'; break;
    }
  } else
    Value = TokStart[1];

  return AsmToken(AsmToken::Integer, Res, Value);
}

/// LexQuote: String: "..."
AsmToken AsmLexer::LexQuote() {
  int CurChar = getNextChar();
  if (LexMasmStrings) {
    while (CurChar != EOF) {
      if (CurChar != '"') {
        CurChar = getNextChar();
      } else if (peekNextChar() == '"') {
        // In MASM double-quoted strings, doubled double-quotes mean an escaped
        // double quote, so should be lexed in.
        getNextChar();
        CurChar = getNextChar();
      } else {
        break;
      }
    }
    if (CurChar == EOF)
      return ReturnError(TokStart, "unterminated string constant");
    return AsmToken(AsmToken::String, StringRef(TokStart, CurPtr - TokStart));
  }

  // TODO: does gas allow multiline string constants?
  while (CurChar != '"') {
    if (CurChar == '\\') {
      // Allow \", etc.
      CurChar = getNextChar();
    }

    if (CurChar == EOF)
      return ReturnError(TokStart, "unterminated string constant");

    CurChar = getNextChar();
  }

  return AsmToken(AsmToken::String, StringRef(TokStart, CurPtr - TokStart));
}

StringRef AsmLexer::LexUntilEndOfStatement() {
  TokStart = CurPtr;

  while (!isAtStartOfComment(CurPtr) &&     // Start of line comment.
         !isAtStatementSeparator(CurPtr) && // End of statement marker.
         *CurPtr != '\n' && *CurPtr != '\r' && CurPtr != CurBuf.end()) {
    ++CurPtr;
  }
  return StringRef(TokStart, CurPtr-TokStart);
}

StringRef AsmLexer::LexUntilEndOfLine() {
  TokStart = CurPtr;

  while (*CurPtr != '\n' && *CurPtr != '\r' && CurPtr != CurBuf.end()) {
    ++CurPtr;
  }
  return StringRef(TokStart, CurPtr-TokStart);
}

size_t AsmLexer::peekTokens(MutableArrayRef<AsmToken> Buf,
                            bool ShouldSkipSpace) {
  SaveAndRestore<const char *> SavedTokenStart(TokStart);
  SaveAndRestore<const char *> SavedCurPtr(CurPtr);
  SaveAndRestore<bool> SavedAtStartOfLine(IsAtStartOfLine);
  SaveAndRestore<bool> SavedAtStartOfStatement(IsAtStartOfStatement);
  SaveAndRestore<bool> SavedSkipSpace(SkipSpace, ShouldSkipSpace);
  SaveAndRestore<bool> SavedIsPeeking(IsPeeking, true);
  std::string SavedErr = getErr();
  SMLoc SavedErrLoc = getErrLoc();

  size_t ReadCount;
  for (ReadCount = 0; ReadCount < Buf.size(); ++ReadCount) {
    AsmToken Token = LexToken();

    Buf[ReadCount] = Token;

    if (Token.is(AsmToken::Eof))
      break;
  }

  SetError(SavedErrLoc, SavedErr);
  return ReadCount;
}

bool AsmLexer::isAtStartOfComment(const char *Ptr) {
  StringRef CommentString = MAI.getCommentString();

  if (CommentString.size() == 1)
    return CommentString[0] == Ptr[0];

  // Allow # preprocessor commments also be counted as comments for "##" cases
  if (CommentString[1] == '#')
    return CommentString[0] == Ptr[0];

  return strncmp(Ptr, CommentString.data(), CommentString.size()) == 0;
}

bool AsmLexer::isAtStatementSeparator(const char *Ptr) {
  return strncmp(Ptr, MAI.getSeparatorString(),
                 strlen(MAI.getSeparatorString())) == 0;
}

AsmToken AsmLexer::LexToken() {
  TokStart = CurPtr;
  // This always consumes at least one character.
  int CurChar = getNextChar();

  if (!IsPeeking && CurChar == '#' && IsAtStartOfStatement) {
    // If this starts with a '#', this may be a cpp
    // hash directive and otherwise a line comment.
    AsmToken TokenBuf[2];
    MutableArrayRef<AsmToken> Buf(TokenBuf, 2);
    size_t num = peekTokens(Buf, true);
    // There cannot be a space preceding this
    if (IsAtStartOfLine && num == 2 && TokenBuf[0].is(AsmToken::Integer) &&
        TokenBuf[1].is(AsmToken::String)) {
      CurPtr = TokStart; // reset curPtr;
      StringRef s = LexUntilEndOfLine();
      UnLex(TokenBuf[1]);
      UnLex(TokenBuf[0]);
      return AsmToken(AsmToken::HashDirective, s);
    }
    return LexLineComment();
  }

  if (isAtStartOfComment(TokStart))
    return LexLineComment();

  if (isAtStatementSeparator(TokStart)) {
    CurPtr += strlen(MAI.getSeparatorString()) - 1;
    IsAtStartOfLine = true;
    IsAtStartOfStatement = true;
    return AsmToken(AsmToken::EndOfStatement,
                    StringRef(TokStart, strlen(MAI.getSeparatorString())));
  }

  // If we're missing a newline at EOF, make sure we still get an
  // EndOfStatement token before the Eof token.
  if (CurChar == EOF && !IsAtStartOfStatement && EndStatementAtEOF) {
    IsAtStartOfLine = true;
    IsAtStartOfStatement = true;
    return AsmToken(AsmToken::EndOfStatement, StringRef(TokStart, 0));
  }
  IsAtStartOfLine = false;
  bool OldIsAtStartOfStatement = IsAtStartOfStatement;
  IsAtStartOfStatement = false;
  switch (CurChar) {
  default:
    if (MAI.doesAllowSymbolAtNameStart()) {
      // Handle Microsoft-style identifier: [a-zA-Z_$.@?][a-zA-Z0-9_$.@?]*
      if (!isDigit(CurChar) &&
          IsIdentifierChar(CurChar, MAI.doesAllowAtInName()))
        return LexIdentifier();
    } else {
      // Handle identifier: [a-zA-Z_.][a-zA-Z0-9_$.@]*
      if (isalpha(CurChar) || CurChar == '_' || CurChar == '.')
        return LexIdentifier();
    }

    // Unknown character, emit an error.
    return ReturnError(TokStart, "invalid character in input");
  case EOF:
    if (EndStatementAtEOF) {
      IsAtStartOfLine = true;
      IsAtStartOfStatement = true;
    }
    return AsmToken(AsmToken::Eof, StringRef(TokStart, 0));
  case 0:
  case ' ':
  case '\t':
    IsAtStartOfStatement = OldIsAtStartOfStatement;
    while (*CurPtr == ' ' || *CurPtr == '\t')
      CurPtr++;
    if (SkipSpace)
      return LexToken(); // Ignore whitespace.
    else
      return AsmToken(AsmToken::Space, StringRef(TokStart, CurPtr - TokStart));
  case '\r': {
    IsAtStartOfLine = true;
    IsAtStartOfStatement = true;
    // If this is a CR followed by LF, treat that as one token.
    if (CurPtr != CurBuf.end() && *CurPtr == '\n')
      ++CurPtr;
    return AsmToken(AsmToken::EndOfStatement,
                    StringRef(TokStart, CurPtr - TokStart));
  }
  case '\n':
    IsAtStartOfLine = true;
    IsAtStartOfStatement = true;
    return AsmToken(AsmToken::EndOfStatement, StringRef(TokStart, 1));
  case ':': return AsmToken(AsmToken::Colon, StringRef(TokStart, 1));
  case '+': return AsmToken(AsmToken::Plus, StringRef(TokStart, 1));
  case '~': return AsmToken(AsmToken::Tilde, StringRef(TokStart, 1));
  case '(': return AsmToken(AsmToken::LParen, StringRef(TokStart, 1));
  case ')': return AsmToken(AsmToken::RParen, StringRef(TokStart, 1));
  case '[': return AsmToken(AsmToken::LBrac, StringRef(TokStart, 1));
  case ']': return AsmToken(AsmToken::RBrac, StringRef(TokStart, 1));
  case '{': return AsmToken(AsmToken::LCurly, StringRef(TokStart, 1));
  case '}': return AsmToken(AsmToken::RCurly, StringRef(TokStart, 1));
  case '*': return AsmToken(AsmToken::Star, StringRef(TokStart, 1));
  case ',': return AsmToken(AsmToken::Comma, StringRef(TokStart, 1));
  case '$': return AsmToken(AsmToken::Dollar, StringRef(TokStart, 1));
  case '@': return AsmToken(AsmToken::At, StringRef(TokStart, 1));
  case '\\': return AsmToken(AsmToken::BackSlash, StringRef(TokStart, 1));
  case '=':
    if (*CurPtr == '=') {
      ++CurPtr;
      return AsmToken(AsmToken::EqualEqual, StringRef(TokStart, 2));
    }
    return AsmToken(AsmToken::Equal, StringRef(TokStart, 1));
  case '-':
    if (*CurPtr == '>') {
      ++CurPtr;
      return AsmToken(AsmToken::MinusGreater, StringRef(TokStart, 2));
    }
    return AsmToken(AsmToken::Minus, StringRef(TokStart, 1));
  case '|':
    if (*CurPtr == '|') {
      ++CurPtr;
      return AsmToken(AsmToken::PipePipe, StringRef(TokStart, 2));
    }
    return AsmToken(AsmToken::Pipe, StringRef(TokStart, 1));
  case '^': return AsmToken(AsmToken::Caret, StringRef(TokStart, 1));
  case '&':
    if (*CurPtr == '&') {
      ++CurPtr;
      return AsmToken(AsmToken::AmpAmp, StringRef(TokStart, 2));
    }
    return AsmToken(AsmToken::Amp, StringRef(TokStart, 1));
  case '!':
    if (*CurPtr == '=') {
      ++CurPtr;
      return AsmToken(AsmToken::ExclaimEqual, StringRef(TokStart, 2));
    }
    return AsmToken(AsmToken::Exclaim, StringRef(TokStart, 1));
  case '%':
    if (MAI.hasMipsExpressions()) {
      AsmToken::TokenKind Operator;
      unsigned OperatorLength;

      std::tie(Operator, OperatorLength) =
          StringSwitch<std::pair<AsmToken::TokenKind, unsigned>>(
              StringRef(CurPtr))
              .StartsWith("call16", {AsmToken::PercentCall16, 7})
              .StartsWith("call_hi", {AsmToken::PercentCall_Hi, 8})
              .StartsWith("call_lo", {AsmToken::PercentCall_Lo, 8})
              .StartsWith("dtprel_hi", {AsmToken::PercentDtprel_Hi, 10})
              .StartsWith("dtprel_lo", {AsmToken::PercentDtprel_Lo, 10})
              .StartsWith("got_disp", {AsmToken::PercentGot_Disp, 9})
              .StartsWith("got_hi", {AsmToken::PercentGot_Hi, 7})
              .StartsWith("got_lo", {AsmToken::PercentGot_Lo, 7})
              .StartsWith("got_ofst", {AsmToken::PercentGot_Ofst, 9})
              .StartsWith("got_page", {AsmToken::PercentGot_Page, 9})
              .StartsWith("gottprel", {AsmToken::PercentGottprel, 9})
              .StartsWith("got", {AsmToken::PercentGot, 4})
              .StartsWith("gp_rel", {AsmToken::PercentGp_Rel, 7})
              .StartsWith("higher", {AsmToken::PercentHigher, 7})
              .StartsWith("highest", {AsmToken::PercentHighest, 8})
              .StartsWith("hi", {AsmToken::PercentHi, 3})
              .StartsWith("lo", {AsmToken::PercentLo, 3})
              .StartsWith("neg", {AsmToken::PercentNeg, 4})
              .StartsWith("pcrel_hi", {AsmToken::PercentPcrel_Hi, 9})
              .StartsWith("pcrel_lo", {AsmToken::PercentPcrel_Lo, 9})
              .StartsWith("tlsgd", {AsmToken::PercentTlsgd, 6})
              .StartsWith("tlsldm", {AsmToken::PercentTlsldm, 7})
              .StartsWith("tprel_hi", {AsmToken::PercentTprel_Hi, 9})
              .StartsWith("tprel_lo", {AsmToken::PercentTprel_Lo, 9})
              .Default({AsmToken::Percent, 1});

      if (Operator != AsmToken::Percent) {
        CurPtr += OperatorLength - 1;
        return AsmToken(Operator, StringRef(TokStart, OperatorLength));
      }
    }
    return AsmToken(AsmToken::Percent, StringRef(TokStart, 1));
  case '/':
    IsAtStartOfStatement = OldIsAtStartOfStatement;
    return LexSlash();
  case '#': return AsmToken(AsmToken::Hash, StringRef(TokStart, 1));
  case '\'': return LexSingleQuote();
  case '"': return LexQuote();
  case '0': case '1': case '2': case '3': case '4':
  case '5': case '6': case '7': case '8': case '9':
    return LexDigit();
  case '<':
    switch (*CurPtr) {
    case '<':
      ++CurPtr;
      return AsmToken(AsmToken::LessLess, StringRef(TokStart, 2));
    case '=':
      ++CurPtr;
      return AsmToken(AsmToken::LessEqual, StringRef(TokStart, 2));
    case '>':
      ++CurPtr;
      return AsmToken(AsmToken::LessGreater, StringRef(TokStart, 2));
    default:
      return AsmToken(AsmToken::Less, StringRef(TokStart, 1));
    }
  case '>':
    switch (*CurPtr) {
    case '>':
      ++CurPtr;
      return AsmToken(AsmToken::GreaterGreater, StringRef(TokStart, 2));
    case '=':
      ++CurPtr;
      return AsmToken(AsmToken::GreaterEqual, StringRef(TokStart, 2));
    default:
      return AsmToken(AsmToken::Greater, StringRef(TokStart, 1));
    }

  // TODO: Quoted identifiers (objc methods etc)
  // local labels: [0-9][:]
  // Forward/backward labels: [0-9][fb]
  // Integers, fp constants, character constants.
  }
}