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(".cfi_same_value", MIToken::kw_cfi_same_value)
209       .Case(".cfi_offset", MIToken::kw_cfi_offset)
210       .Case(".cfi_def_cfa_register", MIToken::kw_cfi_def_cfa_register)
211       .Case(".cfi_def_cfa_offset", MIToken::kw_cfi_def_cfa_offset)
212       .Case(".cfi_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() != '_' && 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 static Cursor maybeLexRegister(Cursor C, MIToken &Token) {
376   if (C.peek() != '%')
377     return None;
378   if (isdigit(C.peek(1)))
379     return lexVirtualRegister(C, Token);
380   auto Range = C;
381   C.advance(); // Skip '%'
382   while (isIdentifierChar(C.peek()))
383     C.advance();
384   Token.reset(MIToken::NamedRegister, Range.upto(C))
385       .setStringValue(Range.upto(C).drop_front(1)); // Drop the '%'
386   return C;
387 }
388 
389 static Cursor maybeLexGlobalValue(Cursor C, MIToken &Token,
390                                   ErrorCallbackType ErrorCallback) {
391   if (C.peek() != '@')
392     return None;
393   if (!isdigit(C.peek(1)))
394     return lexName(C, Token, MIToken::NamedGlobalValue, /*PrefixLength=*/1,
395                    ErrorCallback);
396   auto Range = C;
397   C.advance(1); // Skip the '@'
398   auto NumberRange = C;
399   while (isdigit(C.peek()))
400     C.advance();
401   Token.reset(MIToken::GlobalValue, Range.upto(C))
402       .setIntegerValue(APSInt(NumberRange.upto(C)));
403   return C;
404 }
405 
406 static Cursor maybeLexExternalSymbol(Cursor C, MIToken &Token,
407                                      ErrorCallbackType ErrorCallback) {
408   if (C.peek() != '$')
409     return None;
410   return lexName(C, Token, MIToken::ExternalSymbol, /*PrefixLength=*/1,
411                  ErrorCallback);
412 }
413 
414 static bool isValidHexFloatingPointPrefix(char C) {
415   return C == 'H' || C == 'K' || C == 'L' || C == 'M';
416 }
417 
418 static Cursor maybeLexHexFloatingPointLiteral(Cursor C, MIToken &Token) {
419   if (C.peek() != '0' || C.peek(1) != 'x')
420     return None;
421   Cursor Range = C;
422   C.advance(2); // Skip '0x'
423   if (isValidHexFloatingPointPrefix(C.peek()))
424     C.advance();
425   while (isxdigit(C.peek()))
426     C.advance();
427   Token.reset(MIToken::FloatingPointLiteral, Range.upto(C));
428   return C;
429 }
430 
431 static Cursor lexFloatingPointLiteral(Cursor Range, Cursor C, MIToken &Token) {
432   C.advance();
433   // Skip over [0-9]*([eE][-+]?[0-9]+)?
434   while (isdigit(C.peek()))
435     C.advance();
436   if ((C.peek() == 'e' || C.peek() == 'E') &&
437       (isdigit(C.peek(1)) ||
438        ((C.peek(1) == '-' || C.peek(1) == '+') && isdigit(C.peek(2))))) {
439     C.advance(2);
440     while (isdigit(C.peek()))
441       C.advance();
442   }
443   Token.reset(MIToken::FloatingPointLiteral, Range.upto(C));
444   return C;
445 }
446 
447 static Cursor maybeLexNumericalLiteral(Cursor C, MIToken &Token) {
448   if (!isdigit(C.peek()) && (C.peek() != '-' || !isdigit(C.peek(1))))
449     return None;
450   auto Range = C;
451   C.advance();
452   while (isdigit(C.peek()))
453     C.advance();
454   if (C.peek() == '.')
455     return lexFloatingPointLiteral(Range, C, Token);
456   StringRef StrVal = Range.upto(C);
457   Token.reset(MIToken::IntegerLiteral, StrVal).setIntegerValue(APSInt(StrVal));
458   return C;
459 }
460 
461 static MIToken::TokenKind getMetadataKeywordKind(StringRef Identifier) {
462   return StringSwitch<MIToken::TokenKind>(Identifier)
463       .Case("!tbaa", MIToken::md_tbaa)
464       .Case("!alias.scope", MIToken::md_alias_scope)
465       .Case("!noalias", MIToken::md_noalias)
466       .Case("!range", MIToken::md_range)
467       .Default(MIToken::Error);
468 }
469 
470 static Cursor maybeLexExlaim(Cursor C, MIToken &Token,
471                              ErrorCallbackType ErrorCallback) {
472   if (C.peek() != '!')
473     return None;
474   auto Range = C;
475   C.advance(1);
476   if (isdigit(C.peek()) || !isIdentifierChar(C.peek())) {
477     Token.reset(MIToken::exclaim, Range.upto(C));
478     return C;
479   }
480   while (isIdentifierChar(C.peek()))
481     C.advance();
482   StringRef StrVal = Range.upto(C);
483   Token.reset(getMetadataKeywordKind(StrVal), StrVal);
484   if (Token.isError())
485     ErrorCallback(Token.location(),
486                   "use of unknown metadata keyword '" + StrVal + "'");
487   return C;
488 }
489 
490 static MIToken::TokenKind symbolToken(char C) {
491   switch (C) {
492   case ',':
493     return MIToken::comma;
494   case '=':
495     return MIToken::equal;
496   case ':':
497     return MIToken::colon;
498   case '(':
499     return MIToken::lparen;
500   case ')':
501     return MIToken::rparen;
502   case '{':
503     return MIToken::lbrace;
504   case '}':
505     return MIToken::rbrace;
506   case '+':
507     return MIToken::plus;
508   case '-':
509     return MIToken::minus;
510   case '<':
511     return MIToken::less;
512   case '>':
513     return MIToken::greater;
514   default:
515     return MIToken::Error;
516   }
517 }
518 
519 static Cursor maybeLexSymbol(Cursor C, MIToken &Token) {
520   MIToken::TokenKind Kind;
521   unsigned Length = 1;
522   if (C.peek() == ':' && C.peek(1) == ':') {
523     Kind = MIToken::coloncolon;
524     Length = 2;
525   } else
526     Kind = symbolToken(C.peek());
527   if (Kind == MIToken::Error)
528     return None;
529   auto Range = C;
530   C.advance(Length);
531   Token.reset(Kind, Range.upto(C));
532   return C;
533 }
534 
535 static Cursor maybeLexNewline(Cursor C, MIToken &Token) {
536   if (!isNewlineChar(C.peek()))
537     return None;
538   auto Range = C;
539   C.advance();
540   Token.reset(MIToken::Newline, Range.upto(C));
541   return C;
542 }
543 
544 static Cursor maybeLexEscapedIRValue(Cursor C, MIToken &Token,
545                                      ErrorCallbackType ErrorCallback) {
546   if (C.peek() != '`')
547     return None;
548   auto Range = C;
549   C.advance();
550   auto StrRange = C;
551   while (C.peek() != '`') {
552     if (C.isEOF() || isNewlineChar(C.peek())) {
553       ErrorCallback(
554           C.location(),
555           "end of machine instruction reached before the closing '`'");
556       Token.reset(MIToken::Error, Range.remaining());
557       return C;
558     }
559     C.advance();
560   }
561   StringRef Value = StrRange.upto(C);
562   C.advance();
563   Token.reset(MIToken::QuotedIRValue, Range.upto(C)).setStringValue(Value);
564   return C;
565 }
566 
567 StringRef llvm::lexMIToken(StringRef Source, MIToken &Token,
568                            ErrorCallbackType ErrorCallback) {
569   auto C = skipComment(skipWhitespace(Cursor(Source)));
570   if (C.isEOF()) {
571     Token.reset(MIToken::Eof, C.remaining());
572     return C.remaining();
573   }
574 
575   if (Cursor R = maybeLexIntegerOrScalarType(C, Token))
576     return R.remaining();
577   if (Cursor R = maybeLexMachineBasicBlock(C, Token, ErrorCallback))
578     return R.remaining();
579   if (Cursor R = maybeLexIdentifier(C, Token))
580     return R.remaining();
581   if (Cursor R = maybeLexJumpTableIndex(C, Token))
582     return R.remaining();
583   if (Cursor R = maybeLexStackObject(C, Token))
584     return R.remaining();
585   if (Cursor R = maybeLexFixedStackObject(C, Token))
586     return R.remaining();
587   if (Cursor R = maybeLexConstantPoolItem(C, Token))
588     return R.remaining();
589   if (Cursor R = maybeLexSubRegisterIndex(C, Token, ErrorCallback))
590     return R.remaining();
591   if (Cursor R = maybeLexIRBlock(C, Token, ErrorCallback))
592     return R.remaining();
593   if (Cursor R = maybeLexIRValue(C, Token, ErrorCallback))
594     return R.remaining();
595   if (Cursor R = maybeLexRegister(C, Token))
596     return R.remaining();
597   if (Cursor R = maybeLexGlobalValue(C, Token, ErrorCallback))
598     return R.remaining();
599   if (Cursor R = maybeLexExternalSymbol(C, Token, ErrorCallback))
600     return R.remaining();
601   if (Cursor R = maybeLexHexFloatingPointLiteral(C, Token))
602     return R.remaining();
603   if (Cursor R = maybeLexNumericalLiteral(C, Token))
604     return R.remaining();
605   if (Cursor R = maybeLexExlaim(C, Token, ErrorCallback))
606     return R.remaining();
607   if (Cursor R = maybeLexSymbol(C, Token))
608     return R.remaining();
609   if (Cursor R = maybeLexNewline(C, Token))
610     return R.remaining();
611   if (Cursor R = maybeLexEscapedIRValue(C, Token, ErrorCallback))
612     return R.remaining();
613 
614   Token.reset(MIToken::Error, C.remaining());
615   ErrorCallback(C.location(),
616                 Twine("unexpected character '") + Twine(C.peek()) + "'");
617   return C.remaining();
618 }
619