1 //===- MILexer.cpp - Machine instructions lexer implementation ------------===//
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 lexing of machine instructions.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "MILexer.h"
15 #include "llvm/ADT/APSInt.h"
16 #include "llvm/ADT/None.h"
17 #include "llvm/ADT/STLExtras.h"
18 #include "llvm/ADT/StringExtras.h"
19 #include "llvm/ADT/StringSwitch.h"
20 #include "llvm/ADT/StringRef.h"
21 #include "llvm/ADT/Twine.h"
22 #include <algorithm>
23 #include <cassert>
24 #include <cctype>
25 #include <string>
26 
27 using namespace llvm;
28 
29 namespace {
30 
31 using ErrorCallbackType =
32     function_ref<void(StringRef::iterator Loc, const Twine &)>;
33 
34 /// This class provides a way to iterate and get characters from the source
35 /// string.
36 class Cursor {
37   const char *Ptr = nullptr;
38   const char *End = nullptr;
39 
40 public:
41   Cursor(NoneType) {}
42 
43   explicit Cursor(StringRef Str) {
44     Ptr = Str.data();
45     End = Ptr + Str.size();
46   }
47 
48   bool isEOF() const { return Ptr == End; }
49 
50   char peek(int I = 0) const { return End - Ptr <= I ? 0 : Ptr[I]; }
51 
52   void advance(unsigned I = 1) { Ptr += I; }
53 
54   StringRef remaining() const { return StringRef(Ptr, End - Ptr); }
55 
56   StringRef upto(Cursor C) const {
57     assert(C.Ptr >= Ptr && C.Ptr <= End);
58     return StringRef(Ptr, C.Ptr - Ptr);
59   }
60 
61   StringRef::iterator location() const { return Ptr; }
62 
63   operator bool() const { return Ptr != nullptr; }
64 };
65 
66 } // end anonymous namespace
67 
68 MIToken &MIToken::reset(TokenKind Kind, StringRef Range) {
69   this->Kind = Kind;
70   this->Range = Range;
71   return *this;
72 }
73 
74 MIToken &MIToken::setStringValue(StringRef StrVal) {
75   StringValue = StrVal;
76   return *this;
77 }
78 
79 MIToken &MIToken::setOwnedStringValue(std::string StrVal) {
80   StringValueStorage = std::move(StrVal);
81   StringValue = StringValueStorage;
82   return *this;
83 }
84 
85 MIToken &MIToken::setIntegerValue(APSInt IntVal) {
86   this->IntVal = std::move(IntVal);
87   return *this;
88 }
89 
90 /// Skip the leading whitespace characters and return the updated cursor.
91 static Cursor skipWhitespace(Cursor C) {
92   while (isblank(C.peek()))
93     C.advance();
94   return C;
95 }
96 
97 static bool isNewlineChar(char C) { return C == '\n' || C == '\r'; }
98 
99 /// Skip a line comment and return the updated cursor.
100 static Cursor skipComment(Cursor C) {
101   if (C.peek() != ';')
102     return C;
103   while (!isNewlineChar(C.peek()) && !C.isEOF())
104     C.advance();
105   return C;
106 }
107 
108 /// Return true if the given character satisfies the following regular
109 /// expression: [-a-zA-Z$._0-9]
110 static bool isIdentifierChar(char C) {
111   return isalpha(C) || isdigit(C) || C == '_' || C == '-' || C == '.' ||
112          C == '$';
113 }
114 
115 /// Unescapes the given string value.
116 ///
117 /// Expects the string value to be quoted.
118 static std::string unescapeQuotedString(StringRef Value) {
119   assert(Value.front() == '"' && Value.back() == '"');
120   Cursor C = Cursor(Value.substr(1, Value.size() - 2));
121 
122   std::string Str;
123   Str.reserve(C.remaining().size());
124   while (!C.isEOF()) {
125     char Char = C.peek();
126     if (Char == '\\') {
127       if (C.peek(1) == '\\') {
128         // Two '\' become one
129         Str += '\\';
130         C.advance(2);
131         continue;
132       }
133       if (isxdigit(C.peek(1)) && isxdigit(C.peek(2))) {
134         Str += hexDigitValue(C.peek(1)) * 16 + hexDigitValue(C.peek(2));
135         C.advance(3);
136         continue;
137       }
138     }
139     Str += Char;
140     C.advance();
141   }
142   return Str;
143 }
144 
145 /// Lex a string constant using the following regular expression: \"[^\"]*\"
146 static Cursor lexStringConstant(Cursor C, ErrorCallbackType ErrorCallback) {
147   assert(C.peek() == '"');
148   for (C.advance(); C.peek() != '"'; C.advance()) {
149     if (C.isEOF() || isNewlineChar(C.peek())) {
150       ErrorCallback(
151           C.location(),
152           "end of machine instruction reached before the closing '\"'");
153       return None;
154     }
155   }
156   C.advance();
157   return C;
158 }
159 
160 static Cursor lexName(Cursor C, MIToken &Token, MIToken::TokenKind Type,
161                       unsigned PrefixLength, ErrorCallbackType ErrorCallback) {
162   auto Range = C;
163   C.advance(PrefixLength);
164   if (C.peek() == '"') {
165     if (Cursor R = lexStringConstant(C, ErrorCallback)) {
166       StringRef String = Range.upto(R);
167       Token.reset(Type, String)
168           .setOwnedStringValue(
169               unescapeQuotedString(String.drop_front(PrefixLength)));
170       return R;
171     }
172     Token.reset(MIToken::Error, Range.remaining());
173     return Range;
174   }
175   while (isIdentifierChar(C.peek()))
176     C.advance();
177   Token.reset(Type, Range.upto(C))
178       .setStringValue(Range.upto(C).drop_front(PrefixLength));
179   return C;
180 }
181 
182 static Cursor maybeLexIntegerOrScalarType(Cursor C, MIToken &Token) {
183   if ((C.peek() != 'i' && C.peek() != 's' && C.peek() != 'p') ||
184       !isdigit(C.peek(1)))
185     return None;
186   char Kind = C.peek();
187   auto Range = C;
188   C.advance(); // Skip 'i', 's', or 'p'
189   while (isdigit(C.peek()))
190     C.advance();
191 
192   Token.reset(Kind == 'i'
193                   ? MIToken::IntegerType
194                   : (Kind == 's' ? MIToken::ScalarType : MIToken::PointerType),
195               Range.upto(C));
196   return C;
197 }
198 
199 static MIToken::TokenKind getIdentifierKind(StringRef Identifier) {
200   return StringSwitch<MIToken::TokenKind>(Identifier)
201       .Case("_", MIToken::underscore)
202       .Case("implicit", MIToken::kw_implicit)
203       .Case("implicit-def", MIToken::kw_implicit_define)
204       .Case("def", MIToken::kw_def)
205       .Case("dead", MIToken::kw_dead)
206       .Case("killed", MIToken::kw_killed)
207       .Case("undef", MIToken::kw_undef)
208       .Case("internal", MIToken::kw_internal)
209       .Case("early-clobber", MIToken::kw_early_clobber)
210       .Case("debug-use", MIToken::kw_debug_use)
211       .Case("renamable", MIToken::kw_renamable)
212       .Case("tied-def", MIToken::kw_tied_def)
213       .Case("frame-setup", MIToken::kw_frame_setup)
214       .Case("frame-destroy", MIToken::kw_frame_destroy)
215       .Case("nnan", MIToken::kw_nnan)
216       .Case("ninf", MIToken::kw_ninf)
217       .Case("nsz", MIToken::kw_nsz)
218       .Case("arcp", MIToken::kw_arcp)
219       .Case("contract", MIToken::kw_contract)
220       .Case("afn", MIToken::kw_afn)
221       .Case("reassoc", MIToken::kw_reassoc)
222       .Case("debug-location", MIToken::kw_debug_location)
223       .Case("same_value", MIToken::kw_cfi_same_value)
224       .Case("offset", MIToken::kw_cfi_offset)
225       .Case("rel_offset", MIToken::kw_cfi_rel_offset)
226       .Case("def_cfa_register", MIToken::kw_cfi_def_cfa_register)
227       .Case("def_cfa_offset", MIToken::kw_cfi_def_cfa_offset)
228       .Case("adjust_cfa_offset", MIToken::kw_cfi_adjust_cfa_offset)
229       .Case("escape", MIToken::kw_cfi_escape)
230       .Case("def_cfa", MIToken::kw_cfi_def_cfa)
231       .Case("remember_state", MIToken::kw_cfi_remember_state)
232       .Case("restore", MIToken::kw_cfi_restore)
233       .Case("restore_state", MIToken::kw_cfi_restore_state)
234       .Case("undefined", MIToken::kw_cfi_undefined)
235       .Case("register", MIToken::kw_cfi_register)
236       .Case("window_save", MIToken::kw_cfi_window_save)
237       .Case("blockaddress", MIToken::kw_blockaddress)
238       .Case("intrinsic", MIToken::kw_intrinsic)
239       .Case("target-index", MIToken::kw_target_index)
240       .Case("half", MIToken::kw_half)
241       .Case("float", MIToken::kw_float)
242       .Case("double", MIToken::kw_double)
243       .Case("x86_fp80", MIToken::kw_x86_fp80)
244       .Case("fp128", MIToken::kw_fp128)
245       .Case("ppc_fp128", MIToken::kw_ppc_fp128)
246       .Case("target-flags", MIToken::kw_target_flags)
247       .Case("volatile", MIToken::kw_volatile)
248       .Case("non-temporal", MIToken::kw_non_temporal)
249       .Case("dereferenceable", MIToken::kw_dereferenceable)
250       .Case("invariant", MIToken::kw_invariant)
251       .Case("align", MIToken::kw_align)
252       .Case("addrspace", MIToken::kw_addrspace)
253       .Case("stack", MIToken::kw_stack)
254       .Case("got", MIToken::kw_got)
255       .Case("jump-table", MIToken::kw_jump_table)
256       .Case("constant-pool", MIToken::kw_constant_pool)
257       .Case("call-entry", MIToken::kw_call_entry)
258       .Case("liveout", MIToken::kw_liveout)
259       .Case("address-taken", MIToken::kw_address_taken)
260       .Case("landing-pad", MIToken::kw_landing_pad)
261       .Case("liveins", MIToken::kw_liveins)
262       .Case("successors", MIToken::kw_successors)
263       .Case("floatpred", MIToken::kw_floatpred)
264       .Case("intpred", MIToken::kw_intpred)
265       .Default(MIToken::Identifier);
266 }
267 
268 static Cursor maybeLexIdentifier(Cursor C, MIToken &Token) {
269   if (!isalpha(C.peek()) && C.peek() != '_')
270     return None;
271   auto Range = C;
272   while (isIdentifierChar(C.peek()))
273     C.advance();
274   auto Identifier = Range.upto(C);
275   Token.reset(getIdentifierKind(Identifier), Identifier)
276       .setStringValue(Identifier);
277   return C;
278 }
279 
280 static Cursor maybeLexMachineBasicBlock(Cursor C, MIToken &Token,
281                                         ErrorCallbackType ErrorCallback) {
282   bool IsReference = C.remaining().startswith("%bb.");
283   if (!IsReference && !C.remaining().startswith("bb."))
284     return None;
285   auto Range = C;
286   unsigned PrefixLength = IsReference ? 4 : 3;
287   C.advance(PrefixLength); // Skip '%bb.' or 'bb.'
288   if (!isdigit(C.peek())) {
289     Token.reset(MIToken::Error, C.remaining());
290     ErrorCallback(C.location(), "expected a number after '%bb.'");
291     return C;
292   }
293   auto NumberRange = C;
294   while (isdigit(C.peek()))
295     C.advance();
296   StringRef Number = NumberRange.upto(C);
297   unsigned StringOffset = PrefixLength + Number.size(); // Drop '%bb.<id>'
298   // TODO: The format bb.<id>.<irname> is supported only when it's not a
299   // reference. Once we deprecate the format where the irname shows up, we
300   // should only lex forward if it is a reference.
301   if (C.peek() == '.') {
302     C.advance(); // Skip '.'
303     ++StringOffset;
304     while (isIdentifierChar(C.peek()))
305       C.advance();
306   }
307   Token.reset(IsReference ? MIToken::MachineBasicBlock
308                           : MIToken::MachineBasicBlockLabel,
309               Range.upto(C))
310       .setIntegerValue(APSInt(Number))
311       .setStringValue(Range.upto(C).drop_front(StringOffset));
312   return C;
313 }
314 
315 static Cursor maybeLexIndex(Cursor C, MIToken &Token, StringRef Rule,
316                             MIToken::TokenKind Kind) {
317   if (!C.remaining().startswith(Rule) || !isdigit(C.peek(Rule.size())))
318     return None;
319   auto Range = C;
320   C.advance(Rule.size());
321   auto NumberRange = C;
322   while (isdigit(C.peek()))
323     C.advance();
324   Token.reset(Kind, Range.upto(C)).setIntegerValue(APSInt(NumberRange.upto(C)));
325   return C;
326 }
327 
328 static Cursor maybeLexIndexAndName(Cursor C, MIToken &Token, StringRef Rule,
329                                    MIToken::TokenKind Kind) {
330   if (!C.remaining().startswith(Rule) || !isdigit(C.peek(Rule.size())))
331     return None;
332   auto Range = C;
333   C.advance(Rule.size());
334   auto NumberRange = C;
335   while (isdigit(C.peek()))
336     C.advance();
337   StringRef Number = NumberRange.upto(C);
338   unsigned StringOffset = Rule.size() + Number.size();
339   if (C.peek() == '.') {
340     C.advance();
341     ++StringOffset;
342     while (isIdentifierChar(C.peek()))
343       C.advance();
344   }
345   Token.reset(Kind, Range.upto(C))
346       .setIntegerValue(APSInt(Number))
347       .setStringValue(Range.upto(C).drop_front(StringOffset));
348   return C;
349 }
350 
351 static Cursor maybeLexJumpTableIndex(Cursor C, MIToken &Token) {
352   return maybeLexIndex(C, Token, "%jump-table.", MIToken::JumpTableIndex);
353 }
354 
355 static Cursor maybeLexStackObject(Cursor C, MIToken &Token) {
356   return maybeLexIndexAndName(C, Token, "%stack.", MIToken::StackObject);
357 }
358 
359 static Cursor maybeLexFixedStackObject(Cursor C, MIToken &Token) {
360   return maybeLexIndex(C, Token, "%fixed-stack.", MIToken::FixedStackObject);
361 }
362 
363 static Cursor maybeLexConstantPoolItem(Cursor C, MIToken &Token) {
364   return maybeLexIndex(C, Token, "%const.", MIToken::ConstantPoolItem);
365 }
366 
367 static Cursor maybeLexSubRegisterIndex(Cursor C, MIToken &Token,
368                                        ErrorCallbackType ErrorCallback) {
369   const StringRef Rule = "%subreg.";
370   if (!C.remaining().startswith(Rule))
371     return None;
372   return lexName(C, Token, MIToken::SubRegisterIndex, Rule.size(),
373                  ErrorCallback);
374 }
375 
376 static Cursor maybeLexIRBlock(Cursor C, MIToken &Token,
377                               ErrorCallbackType ErrorCallback) {
378   const StringRef Rule = "%ir-block.";
379   if (!C.remaining().startswith(Rule))
380     return None;
381   if (isdigit(C.peek(Rule.size())))
382     return maybeLexIndex(C, Token, Rule, MIToken::IRBlock);
383   return lexName(C, Token, MIToken::NamedIRBlock, Rule.size(), ErrorCallback);
384 }
385 
386 static Cursor maybeLexIRValue(Cursor C, MIToken &Token,
387                               ErrorCallbackType ErrorCallback) {
388   const StringRef Rule = "%ir.";
389   if (!C.remaining().startswith(Rule))
390     return None;
391   if (isdigit(C.peek(Rule.size())))
392     return maybeLexIndex(C, Token, Rule, MIToken::IRValue);
393   return lexName(C, Token, MIToken::NamedIRValue, Rule.size(), ErrorCallback);
394 }
395 
396 static Cursor maybeLexStringConstant(Cursor C, MIToken &Token,
397                                      ErrorCallbackType ErrorCallback) {
398   if (C.peek() != '"')
399     return None;
400   return lexName(C, Token, MIToken::StringConstant, /*PrefixLength=*/0,
401                  ErrorCallback);
402 }
403 
404 static Cursor lexVirtualRegister(Cursor C, MIToken &Token) {
405   auto Range = C;
406   C.advance(); // Skip '%'
407   auto NumberRange = C;
408   while (isdigit(C.peek()))
409     C.advance();
410   Token.reset(MIToken::VirtualRegister, Range.upto(C))
411       .setIntegerValue(APSInt(NumberRange.upto(C)));
412   return C;
413 }
414 
415 /// Returns true for a character allowed in a register name.
416 static bool isRegisterChar(char C) {
417   return isIdentifierChar(C) && C != '.';
418 }
419 
420 static Cursor lexNamedVirtualRegister(Cursor C, MIToken &Token) {
421   Cursor Range = C;
422   C.advance(); // Skip '%'
423   while (isRegisterChar(C.peek()))
424     C.advance();
425   Token.reset(MIToken::NamedVirtualRegister, Range.upto(C))
426       .setStringValue(Range.upto(C).drop_front(1)); // Drop the '%'
427   return C;
428 }
429 
430 static Cursor maybeLexRegister(Cursor C, MIToken &Token,
431                                ErrorCallbackType ErrorCallback) {
432   if (C.peek() != '%' && C.peek() != '$')
433     return None;
434 
435   if (C.peek() == '%') {
436     if (isdigit(C.peek(1)))
437       return lexVirtualRegister(C, Token);
438 
439     if (isRegisterChar(C.peek(1)))
440       return lexNamedVirtualRegister(C, Token);
441 
442     return None;
443   }
444 
445   assert(C.peek() == '$');
446   auto Range = C;
447   C.advance(); // Skip '$'
448   while (isRegisterChar(C.peek()))
449     C.advance();
450   Token.reset(MIToken::NamedRegister, Range.upto(C))
451       .setStringValue(Range.upto(C).drop_front(1)); // Drop the '$'
452   return C;
453 }
454 
455 static Cursor maybeLexGlobalValue(Cursor C, MIToken &Token,
456                                   ErrorCallbackType ErrorCallback) {
457   if (C.peek() != '@')
458     return None;
459   if (!isdigit(C.peek(1)))
460     return lexName(C, Token, MIToken::NamedGlobalValue, /*PrefixLength=*/1,
461                    ErrorCallback);
462   auto Range = C;
463   C.advance(1); // Skip the '@'
464   auto NumberRange = C;
465   while (isdigit(C.peek()))
466     C.advance();
467   Token.reset(MIToken::GlobalValue, Range.upto(C))
468       .setIntegerValue(APSInt(NumberRange.upto(C)));
469   return C;
470 }
471 
472 static Cursor maybeLexExternalSymbol(Cursor C, MIToken &Token,
473                                      ErrorCallbackType ErrorCallback) {
474   if (C.peek() != '&')
475     return None;
476   return lexName(C, Token, MIToken::ExternalSymbol, /*PrefixLength=*/1,
477                  ErrorCallback);
478 }
479 
480 static bool isValidHexFloatingPointPrefix(char C) {
481   return C == 'H' || C == 'K' || C == 'L' || C == 'M';
482 }
483 
484 static Cursor lexFloatingPointLiteral(Cursor Range, Cursor C, MIToken &Token) {
485   C.advance();
486   // Skip over [0-9]*([eE][-+]?[0-9]+)?
487   while (isdigit(C.peek()))
488     C.advance();
489   if ((C.peek() == 'e' || C.peek() == 'E') &&
490       (isdigit(C.peek(1)) ||
491        ((C.peek(1) == '-' || C.peek(1) == '+') && isdigit(C.peek(2))))) {
492     C.advance(2);
493     while (isdigit(C.peek()))
494       C.advance();
495   }
496   Token.reset(MIToken::FloatingPointLiteral, Range.upto(C));
497   return C;
498 }
499 
500 static Cursor maybeLexHexadecimalLiteral(Cursor C, MIToken &Token) {
501   if (C.peek() != '0' || (C.peek(1) != 'x' && C.peek(1) != 'X'))
502     return None;
503   Cursor Range = C;
504   C.advance(2);
505   unsigned PrefLen = 2;
506   if (isValidHexFloatingPointPrefix(C.peek())) {
507     C.advance();
508     PrefLen++;
509   }
510   while (isxdigit(C.peek()))
511     C.advance();
512   StringRef StrVal = Range.upto(C);
513   if (StrVal.size() <= PrefLen)
514     return None;
515   if (PrefLen == 2)
516     Token.reset(MIToken::HexLiteral, Range.upto(C));
517   else // It must be 3, which means that there was a floating-point prefix.
518     Token.reset(MIToken::FloatingPointLiteral, Range.upto(C));
519   return C;
520 }
521 
522 static Cursor maybeLexNumericalLiteral(Cursor C, MIToken &Token) {
523   if (!isdigit(C.peek()) && (C.peek() != '-' || !isdigit(C.peek(1))))
524     return None;
525   auto Range = C;
526   C.advance();
527   while (isdigit(C.peek()))
528     C.advance();
529   if (C.peek() == '.')
530     return lexFloatingPointLiteral(Range, C, Token);
531   StringRef StrVal = Range.upto(C);
532   Token.reset(MIToken::IntegerLiteral, StrVal).setIntegerValue(APSInt(StrVal));
533   return C;
534 }
535 
536 static MIToken::TokenKind getMetadataKeywordKind(StringRef Identifier) {
537   return StringSwitch<MIToken::TokenKind>(Identifier)
538       .Case("!tbaa", MIToken::md_tbaa)
539       .Case("!alias.scope", MIToken::md_alias_scope)
540       .Case("!noalias", MIToken::md_noalias)
541       .Case("!range", MIToken::md_range)
542       .Case("!DIExpression", MIToken::md_diexpr)
543       .Default(MIToken::Error);
544 }
545 
546 static Cursor maybeLexExlaim(Cursor C, MIToken &Token,
547                              ErrorCallbackType ErrorCallback) {
548   if (C.peek() != '!')
549     return None;
550   auto Range = C;
551   C.advance(1);
552   if (isdigit(C.peek()) || !isIdentifierChar(C.peek())) {
553     Token.reset(MIToken::exclaim, Range.upto(C));
554     return C;
555   }
556   while (isIdentifierChar(C.peek()))
557     C.advance();
558   StringRef StrVal = Range.upto(C);
559   Token.reset(getMetadataKeywordKind(StrVal), StrVal);
560   if (Token.isError())
561     ErrorCallback(Token.location(),
562                   "use of unknown metadata keyword '" + StrVal + "'");
563   return C;
564 }
565 
566 static MIToken::TokenKind symbolToken(char C) {
567   switch (C) {
568   case ',':
569     return MIToken::comma;
570   case '.':
571     return MIToken::dot;
572   case '=':
573     return MIToken::equal;
574   case ':':
575     return MIToken::colon;
576   case '(':
577     return MIToken::lparen;
578   case ')':
579     return MIToken::rparen;
580   case '{':
581     return MIToken::lbrace;
582   case '}':
583     return MIToken::rbrace;
584   case '+':
585     return MIToken::plus;
586   case '-':
587     return MIToken::minus;
588   case '<':
589     return MIToken::less;
590   case '>':
591     return MIToken::greater;
592   default:
593     return MIToken::Error;
594   }
595 }
596 
597 static Cursor maybeLexSymbol(Cursor C, MIToken &Token) {
598   MIToken::TokenKind Kind;
599   unsigned Length = 1;
600   if (C.peek() == ':' && C.peek(1) == ':') {
601     Kind = MIToken::coloncolon;
602     Length = 2;
603   } else
604     Kind = symbolToken(C.peek());
605   if (Kind == MIToken::Error)
606     return None;
607   auto Range = C;
608   C.advance(Length);
609   Token.reset(Kind, Range.upto(C));
610   return C;
611 }
612 
613 static Cursor maybeLexNewline(Cursor C, MIToken &Token) {
614   if (!isNewlineChar(C.peek()))
615     return None;
616   auto Range = C;
617   C.advance();
618   Token.reset(MIToken::Newline, Range.upto(C));
619   return C;
620 }
621 
622 static Cursor maybeLexEscapedIRValue(Cursor C, MIToken &Token,
623                                      ErrorCallbackType ErrorCallback) {
624   if (C.peek() != '`')
625     return None;
626   auto Range = C;
627   C.advance();
628   auto StrRange = C;
629   while (C.peek() != '`') {
630     if (C.isEOF() || isNewlineChar(C.peek())) {
631       ErrorCallback(
632           C.location(),
633           "end of machine instruction reached before the closing '`'");
634       Token.reset(MIToken::Error, Range.remaining());
635       return C;
636     }
637     C.advance();
638   }
639   StringRef Value = StrRange.upto(C);
640   C.advance();
641   Token.reset(MIToken::QuotedIRValue, Range.upto(C)).setStringValue(Value);
642   return C;
643 }
644 
645 StringRef llvm::lexMIToken(StringRef Source, MIToken &Token,
646                            ErrorCallbackType ErrorCallback) {
647   auto C = skipComment(skipWhitespace(Cursor(Source)));
648   if (C.isEOF()) {
649     Token.reset(MIToken::Eof, C.remaining());
650     return C.remaining();
651   }
652 
653   if (Cursor R = maybeLexIntegerOrScalarType(C, Token))
654     return R.remaining();
655   if (Cursor R = maybeLexMachineBasicBlock(C, Token, ErrorCallback))
656     return R.remaining();
657   if (Cursor R = maybeLexIdentifier(C, Token))
658     return R.remaining();
659   if (Cursor R = maybeLexJumpTableIndex(C, Token))
660     return R.remaining();
661   if (Cursor R = maybeLexStackObject(C, Token))
662     return R.remaining();
663   if (Cursor R = maybeLexFixedStackObject(C, Token))
664     return R.remaining();
665   if (Cursor R = maybeLexConstantPoolItem(C, Token))
666     return R.remaining();
667   if (Cursor R = maybeLexSubRegisterIndex(C, Token, ErrorCallback))
668     return R.remaining();
669   if (Cursor R = maybeLexIRBlock(C, Token, ErrorCallback))
670     return R.remaining();
671   if (Cursor R = maybeLexIRValue(C, Token, ErrorCallback))
672     return R.remaining();
673   if (Cursor R = maybeLexRegister(C, Token, ErrorCallback))
674     return R.remaining();
675   if (Cursor R = maybeLexGlobalValue(C, Token, ErrorCallback))
676     return R.remaining();
677   if (Cursor R = maybeLexExternalSymbol(C, Token, ErrorCallback))
678     return R.remaining();
679   if (Cursor R = maybeLexHexadecimalLiteral(C, Token))
680     return R.remaining();
681   if (Cursor R = maybeLexNumericalLiteral(C, Token))
682     return R.remaining();
683   if (Cursor R = maybeLexExlaim(C, Token, ErrorCallback))
684     return R.remaining();
685   if (Cursor R = maybeLexSymbol(C, Token))
686     return R.remaining();
687   if (Cursor R = maybeLexNewline(C, Token))
688     return R.remaining();
689   if (Cursor R = maybeLexEscapedIRValue(C, Token, ErrorCallback))
690     return R.remaining();
691   if (Cursor R = maybeLexStringConstant(C, Token, ErrorCallback))
692     return R.remaining();
693 
694   Token.reset(MIToken::Error, C.remaining());
695   ErrorCallback(C.location(),
696                 Twine("unexpected character '") + Twine(C.peek()) + "'");
697   return C.remaining();
698 }
699