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