llvm.org GIT mirror llvm / 1b27914 lib / MC / MCParser / AsmLexer.cpp
1b27914

Tree @1b27914 (Download .tar.gz)

AsmLexer.cpp @1b27914raw · history · 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
//===- AsmLexer.cpp - Lexer for Assembly Files ----------------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This class implements the lexer for assembly files.
//
//===----------------------------------------------------------------------===//

#include "llvm/MC/MCParser/AsmLexer.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/SMLoc.h"
#include <cctype>
#include <cerrno>
#include <cstdio>
#include <cstdlib>
using namespace llvm;

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

AsmLexer::~AsmLexer() {
}

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

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

  TokStart = nullptr;
}

/// 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, 0));
}

int AsmLexer::getNextChar() {
  char CurChar = *CurPtr++;
  switch (CurChar) {
  default:
    return (unsigned char)CurChar;
  case 0:
    // A nul character in the stream is either the end of the current buffer or
    // a random nul in the file.  Disambiguate that here.
    if (CurPtr - 1 != CurBuf.end())
      return 0;  // Just whitespace.

    // Otherwise, return end of file.
    --CurPtr;  // Another call to lex will return EOF again.
    return EOF;
  }
}

/// LexFloatLiteral: [0-9]*[.][0-9]*([eE][+-]?[0-9]*)?
///
/// 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;

  // Check for exponent; we intentionally accept a slighlty wider set of
  // literals here and rely on the upstream client to reject invalid ones (e.g.,
  // "1e+").
  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 (isxdigit(*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 (*CurPtr == 'e' || *CurPtr == 'E' ||
        !IsIdentifierChar(*CurPtr, AllowAtInIdentifier))
      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 '*': break; // C style comment.
  case '/': return ++CurPtr, LexLineComment();
  default:  return AsmToken(AsmToken::Slash, StringRef(CurPtr-1, 1));
  }

  // C Style comment.
  ++CurPtr;  // skip the star.
  while (1) {
    int CurChar = getNextChar();
    switch (CurChar) {
    case EOF:
      return ReturnError(TokStart, "unterminated comment");
    case '*':
      // End of the comment?
      if (CurPtr[0] != '/') break;

      ++CurPtr;   // End the */.
      return LexToken();
    }
  }
}

/// LexLineComment: Comment: #[^\n]*
///                        : //[^\n]*
AsmToken AsmLexer::LexLineComment() {
  // FIXME: This is broken if we happen to a comment at the end of a file, which
  // was .included, and which doesn't end with a newline.
  int CurChar = getNextChar();
  while (CurChar != '\n' && CurChar != '\r' && CurChar != EOF)
    CurChar = getNextChar();

  if (CurChar == EOF)
    return AsmToken(AsmToken::Eof, StringRef(TokStart, 0));
  return AsmToken(AsmToken::EndOfStatement, StringRef(TokStart, 0));
}

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 doLookAhead(const char *&CurPtr, unsigned DefaultRadix) {
  const char *FirstHex = nullptr;
  const char *LookAhead = CurPtr;
  while (1) {
    if (isdigit(*LookAhead)) {
      ++LookAhead;
    } else if (isxdigit(*LookAhead)) {
      if (!FirstHex)
        FirstHex = LookAhead;
      ++LookAhead;
    } else {
      break;
    }
  }
  bool isHex = *LookAhead == 'h' || *LookAhead == 'H';
  CurPtr = isHex || !FirstHex ? LookAhead : FirstHex;
  if (isHex)
    return 16;
  return DefaultRadix;
}

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

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

    StringRef Result(TokStart, CurPtr - TokStart);

    APInt Value(128, 0, true);
    if (Result.getAsInteger(Radix, Value))
      return ReturnError(TokStart, !isHex ? "invalid decimal number" :
                           "invalid hexdecimal number");

    // Consume the [bB][hH].
    if (Radix == 2 || Radix == 16)
      ++CurPtr;

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

    return intToken(Result, Value);
  }

  if (*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;
    const char *NumStart = CurPtr;
    while (isxdigit(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 (*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 = doLookAhead(CurPtr, 8);
  bool isHex = Radix == 16;
  StringRef Result(TokStart, CurPtr - TokStart);
  if (Result.getAsInteger(Radix, Value))
    return ReturnError(TokStart, !isHex ? "invalid octal number" :
                       "invalid hexdecimal 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 (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();
  // 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 != 0 || CurPtr != CurBuf.end())) {
    ++CurPtr;
  }
  return StringRef(TokStart, CurPtr-TokStart);
}

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

  while (*CurPtr != '\n' && *CurPtr != '\r' &&
         (*CurPtr != 0 || CurPtr != CurBuf.end())) {
    ++CurPtr;
  }
  return StringRef(TokStart, CurPtr-TokStart);
}

const AsmToken AsmLexer::peekTok(bool ShouldSkipSpace) {
  const char *SavedTokStart = TokStart;
  const char *SavedCurPtr = CurPtr;
  bool SavedAtStartOfLine = isAtStartOfLine;
  bool SavedSkipSpace = SkipSpace;

  std::string SavedErr = getErr();
  SMLoc SavedErrLoc = getErrLoc();

  SkipSpace = ShouldSkipSpace;
  AsmToken Token = LexToken();

  SetError(SavedErrLoc, SavedErr);

  SkipSpace = SavedSkipSpace;
  isAtStartOfLine = SavedAtStartOfLine;
  CurPtr = SavedCurPtr;
  TokStart = SavedTokStart;

  return Token;
}

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

  if (CommentString[1] == '\0')
    return CommentString[0] == Ptr[0];

  // FIXME: special case for the bogus "##" comment string in X86MCAsmInfoDarwin
  if (CommentString[1] == '#')
    return CommentString[0] == Ptr[0];

  return strncmp(Ptr, CommentString, strlen(CommentString)) == 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 (isAtStartOfComment(TokStart)) {
    // If this comment starts with a '#', then return the Hash token and let
    // the assembler parser see if it can be parsed as a cpp line filename
    // comment. We do this only if we are at the start of a line.
    if (CurChar == '#' && isAtStartOfLine)
      return AsmToken(AsmToken::Hash, StringRef(TokStart, 1));
    isAtStartOfLine = true;
    return LexLineComment();
  }
  if (isAtStatementSeparator(TokStart)) {
    CurPtr += strlen(MAI.getSeparatorString()) - 1;
    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 && !isAtStartOfLine) {
    isAtStartOfLine = true;
    return AsmToken(AsmToken::EndOfStatement, StringRef(TokStart, 1));
  }

  isAtStartOfLine = false;
  switch (CurChar) {
  default:
    // 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: return AsmToken(AsmToken::Eof, StringRef(TokStart, 0));
  case 0:
  case ' ':
  case '\t':
    if (SkipSpace) {
      // Ignore whitespace.
      return LexToken();
    } else {
      int len = 1;
      while (*CurPtr==' ' || *CurPtr=='\t') {
        CurPtr++;
        len++;
      }
      return AsmToken(AsmToken::Space, StringRef(TokStart, len));
    }
  case '\n': // FALL THROUGH.
  case '\r':
    isAtStartOfLine = 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::Minus, 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 == '=')
      return ++CurPtr, AsmToken(AsmToken::EqualEqual, StringRef(TokStart, 2));
    return AsmToken(AsmToken::Equal, StringRef(TokStart, 1));
  case '|':
    if (*CurPtr == '|')
      return ++CurPtr, AsmToken(AsmToken::PipePipe, StringRef(TokStart, 2));
    return AsmToken(AsmToken::Pipe, StringRef(TokStart, 1));
  case '^': return AsmToken(AsmToken::Caret, StringRef(TokStart, 1));
  case '&':
    if (*CurPtr == '&')
      return ++CurPtr, AsmToken(AsmToken::AmpAmp, StringRef(TokStart, 2));
    return AsmToken(AsmToken::Amp, StringRef(TokStart, 1));
  case '!':
    if (*CurPtr == '=')
      return ++CurPtr, AsmToken(AsmToken::ExclaimEqual, StringRef(TokStart, 2));
    return AsmToken(AsmToken::Exclaim, StringRef(TokStart, 1));
  case '%': return AsmToken(AsmToken::Percent, StringRef(TokStart, 1));
  case '/': 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 '<': return ++CurPtr, AsmToken(AsmToken::LessLess,
                                        StringRef(TokStart, 2));
    case '=': return ++CurPtr, AsmToken(AsmToken::LessEqual,
                                        StringRef(TokStart, 2));
    case '>': return ++CurPtr, AsmToken(AsmToken::LessGreater,
                                        StringRef(TokStart, 2));
    default: return AsmToken(AsmToken::Less, StringRef(TokStart, 1));
    }
  case '>':
    switch (*CurPtr) {
    case '>': return ++CurPtr, AsmToken(AsmToken::GreaterGreater,
                                        StringRef(TokStart, 2));
    case '=': return ++CurPtr, 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.
  }
}