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("intrinsic", MIToken::kw_intrinsic)
215       .Case("target-index", MIToken::kw_target_index)
216       .Case("half", MIToken::kw_half)
217       .Case("float", MIToken::kw_float)
218       .Case("double", MIToken::kw_double)
219       .Case("x86_fp80", MIToken::kw_x86_fp80)
220       .Case("fp128", MIToken::kw_fp128)
221       .Case("ppc_fp128", MIToken::kw_ppc_fp128)
222       .Case("target-flags", MIToken::kw_target_flags)
223       .Case("volatile", MIToken::kw_volatile)
224       .Case("non-temporal", MIToken::kw_non_temporal)
225       .Case("invariant", MIToken::kw_invariant)
226       .Case("align", MIToken::kw_align)
227       .Case("stack", MIToken::kw_stack)
228       .Case("got", MIToken::kw_got)
229       .Case("jump-table", MIToken::kw_jump_table)
230       .Case("constant-pool", MIToken::kw_constant_pool)
231       .Case("call-entry", MIToken::kw_call_entry)
232       .Case("liveout", MIToken::kw_liveout)
233       .Case("address-taken", MIToken::kw_address_taken)
234       .Case("landing-pad", MIToken::kw_landing_pad)
235       .Case("liveins", MIToken::kw_liveins)
236       .Case("successors", MIToken::kw_successors)
237       .Default(MIToken::Identifier);
238 }
239 
240 static Cursor maybeLexIdentifier(Cursor C, MIToken &Token) {
241   if (!isalpha(C.peek()) && C.peek() != '_')
242     return None;
243   auto Range = C;
244   while (isIdentifierChar(C.peek()))
245     C.advance();
246   auto Identifier = Range.upto(C);
247   Token.reset(getIdentifierKind(Identifier), Identifier)
248       .setStringValue(Identifier);
249   return C;
250 }
251 
252 static Cursor maybeLexMachineBasicBlock(Cursor C, MIToken &Token,
253                                         ErrorCallbackType ErrorCallback) {
254   bool IsReference = C.remaining().startswith("%bb.");
255   if (!IsReference && !C.remaining().startswith("bb."))
256     return None;
257   auto Range = C;
258   unsigned PrefixLength = IsReference ? 4 : 3;
259   C.advance(PrefixLength); // Skip '%bb.' or 'bb.'
260   if (!isdigit(C.peek())) {
261     Token.reset(MIToken::Error, C.remaining());
262     ErrorCallback(C.location(), "expected a number after '%bb.'");
263     return C;
264   }
265   auto NumberRange = C;
266   while (isdigit(C.peek()))
267     C.advance();
268   StringRef Number = NumberRange.upto(C);
269   unsigned StringOffset = PrefixLength + Number.size(); // Drop '%bb.<id>'
270   if (C.peek() == '.') {
271     C.advance(); // Skip '.'
272     ++StringOffset;
273     while (isIdentifierChar(C.peek()))
274       C.advance();
275   }
276   Token.reset(IsReference ? MIToken::MachineBasicBlock
277                           : MIToken::MachineBasicBlockLabel,
278               Range.upto(C))
279       .setIntegerValue(APSInt(Number))
280       .setStringValue(Range.upto(C).drop_front(StringOffset));
281   return C;
282 }
283 
284 static Cursor maybeLexIndex(Cursor C, MIToken &Token, StringRef Rule,
285                             MIToken::TokenKind Kind) {
286   if (!C.remaining().startswith(Rule) || !isdigit(C.peek(Rule.size())))
287     return None;
288   auto Range = C;
289   C.advance(Rule.size());
290   auto NumberRange = C;
291   while (isdigit(C.peek()))
292     C.advance();
293   Token.reset(Kind, Range.upto(C)).setIntegerValue(APSInt(NumberRange.upto(C)));
294   return C;
295 }
296 
297 static Cursor maybeLexIndexAndName(Cursor C, MIToken &Token, StringRef Rule,
298                                    MIToken::TokenKind Kind) {
299   if (!C.remaining().startswith(Rule) || !isdigit(C.peek(Rule.size())))
300     return None;
301   auto Range = C;
302   C.advance(Rule.size());
303   auto NumberRange = C;
304   while (isdigit(C.peek()))
305     C.advance();
306   StringRef Number = NumberRange.upto(C);
307   unsigned StringOffset = Rule.size() + Number.size();
308   if (C.peek() == '.') {
309     C.advance();
310     ++StringOffset;
311     while (isIdentifierChar(C.peek()))
312       C.advance();
313   }
314   Token.reset(Kind, Range.upto(C))
315       .setIntegerValue(APSInt(Number))
316       .setStringValue(Range.upto(C).drop_front(StringOffset));
317   return C;
318 }
319 
320 static Cursor maybeLexJumpTableIndex(Cursor C, MIToken &Token) {
321   return maybeLexIndex(C, Token, "%jump-table.", MIToken::JumpTableIndex);
322 }
323 
324 static Cursor maybeLexStackObject(Cursor C, MIToken &Token) {
325   return maybeLexIndexAndName(C, Token, "%stack.", MIToken::StackObject);
326 }
327 
328 static Cursor maybeLexFixedStackObject(Cursor C, MIToken &Token) {
329   return maybeLexIndex(C, Token, "%fixed-stack.", MIToken::FixedStackObject);
330 }
331 
332 static Cursor maybeLexConstantPoolItem(Cursor C, MIToken &Token) {
333   return maybeLexIndex(C, Token, "%const.", MIToken::ConstantPoolItem);
334 }
335 
336 static Cursor maybeLexSubRegisterIndex(Cursor C, MIToken &Token,
337                                        ErrorCallbackType ErrorCallback) {
338   const StringRef Rule = "%subreg.";
339   if (!C.remaining().startswith(Rule))
340     return None;
341   return lexName(C, Token, MIToken::SubRegisterIndex, Rule.size(),
342                  ErrorCallback);
343 }
344 
345 static Cursor maybeLexIRBlock(Cursor C, MIToken &Token,
346                               ErrorCallbackType ErrorCallback) {
347   const StringRef Rule = "%ir-block.";
348   if (!C.remaining().startswith(Rule))
349     return None;
350   if (isdigit(C.peek(Rule.size())))
351     return maybeLexIndex(C, Token, Rule, MIToken::IRBlock);
352   return lexName(C, Token, MIToken::NamedIRBlock, Rule.size(), ErrorCallback);
353 }
354 
355 static Cursor maybeLexIRValue(Cursor C, MIToken &Token,
356                               ErrorCallbackType ErrorCallback) {
357   const StringRef Rule = "%ir.";
358   if (!C.remaining().startswith(Rule))
359     return None;
360   if (isdigit(C.peek(Rule.size())))
361     return maybeLexIndex(C, Token, Rule, MIToken::IRValue);
362   return lexName(C, Token, MIToken::NamedIRValue, Rule.size(), ErrorCallback);
363 }
364 
365 static Cursor lexVirtualRegister(Cursor C, MIToken &Token) {
366   auto Range = C;
367   C.advance(); // Skip '%'
368   auto NumberRange = C;
369   while (isdigit(C.peek()))
370     C.advance();
371   Token.reset(MIToken::VirtualRegister, Range.upto(C))
372       .setIntegerValue(APSInt(NumberRange.upto(C)));
373   return C;
374 }
375 
376 /// Returns true for a character allowed in a register name.
377 static bool isRegisterChar(char C) {
378   return isIdentifierChar(C) && C != '.';
379 }
380 
381 static Cursor maybeLexRegister(Cursor C, MIToken &Token) {
382   if (C.peek() != '%')
383     return None;
384   if (isdigit(C.peek(1)))
385     return lexVirtualRegister(C, Token);
386   auto Range = C;
387   C.advance(); // Skip '%'
388   while (isRegisterChar(C.peek()))
389     C.advance();
390   Token.reset(MIToken::NamedRegister, Range.upto(C))
391       .setStringValue(Range.upto(C).drop_front(1)); // Drop the '%'
392   return C;
393 }
394 
395 static Cursor maybeLexGlobalValue(Cursor C, MIToken &Token,
396                                   ErrorCallbackType ErrorCallback) {
397   if (C.peek() != '@')
398     return None;
399   if (!isdigit(C.peek(1)))
400     return lexName(C, Token, MIToken::NamedGlobalValue, /*PrefixLength=*/1,
401                    ErrorCallback);
402   auto Range = C;
403   C.advance(1); // Skip the '@'
404   auto NumberRange = C;
405   while (isdigit(C.peek()))
406     C.advance();
407   Token.reset(MIToken::GlobalValue, Range.upto(C))
408       .setIntegerValue(APSInt(NumberRange.upto(C)));
409   return C;
410 }
411 
412 static Cursor maybeLexExternalSymbol(Cursor C, MIToken &Token,
413                                      ErrorCallbackType ErrorCallback) {
414   if (C.peek() != '$')
415     return None;
416   return lexName(C, Token, MIToken::ExternalSymbol, /*PrefixLength=*/1,
417                  ErrorCallback);
418 }
419 
420 static bool isValidHexFloatingPointPrefix(char C) {
421   return C == 'H' || C == 'K' || C == 'L' || C == 'M';
422 }
423 
424 static Cursor maybeLexHexFloatingPointLiteral(Cursor C, MIToken &Token) {
425   if (C.peek() != '0' || C.peek(1) != 'x')
426     return None;
427   Cursor Range = C;
428   C.advance(2); // Skip '0x'
429   if (isValidHexFloatingPointPrefix(C.peek()))
430     C.advance();
431   while (isxdigit(C.peek()))
432     C.advance();
433   Token.reset(MIToken::FloatingPointLiteral, Range.upto(C));
434   return C;
435 }
436 
437 static Cursor lexFloatingPointLiteral(Cursor Range, Cursor C, MIToken &Token) {
438   C.advance();
439   // Skip over [0-9]*([eE][-+]?[0-9]+)?
440   while (isdigit(C.peek()))
441     C.advance();
442   if ((C.peek() == 'e' || C.peek() == 'E') &&
443       (isdigit(C.peek(1)) ||
444        ((C.peek(1) == '-' || C.peek(1) == '+') && isdigit(C.peek(2))))) {
445     C.advance(2);
446     while (isdigit(C.peek()))
447       C.advance();
448   }
449   Token.reset(MIToken::FloatingPointLiteral, Range.upto(C));
450   return C;
451 }
452 
453 static Cursor maybeLexNumericalLiteral(Cursor C, MIToken &Token) {
454   if (!isdigit(C.peek()) && (C.peek() != '-' || !isdigit(C.peek(1))))
455     return None;
456   auto Range = C;
457   C.advance();
458   while (isdigit(C.peek()))
459     C.advance();
460   if (C.peek() == '.')
461     return lexFloatingPointLiteral(Range, C, Token);
462   StringRef StrVal = Range.upto(C);
463   Token.reset(MIToken::IntegerLiteral, StrVal).setIntegerValue(APSInt(StrVal));
464   return C;
465 }
466 
467 static MIToken::TokenKind getMetadataKeywordKind(StringRef Identifier) {
468   return StringSwitch<MIToken::TokenKind>(Identifier)
469       .Case("!tbaa", MIToken::md_tbaa)
470       .Case("!alias.scope", MIToken::md_alias_scope)
471       .Case("!noalias", MIToken::md_noalias)
472       .Case("!range", MIToken::md_range)
473       .Default(MIToken::Error);
474 }
475 
476 static Cursor maybeLexExlaim(Cursor C, MIToken &Token,
477                              ErrorCallbackType ErrorCallback) {
478   if (C.peek() != '!')
479     return None;
480   auto Range = C;
481   C.advance(1);
482   if (isdigit(C.peek()) || !isIdentifierChar(C.peek())) {
483     Token.reset(MIToken::exclaim, Range.upto(C));
484     return C;
485   }
486   while (isIdentifierChar(C.peek()))
487     C.advance();
488   StringRef StrVal = Range.upto(C);
489   Token.reset(getMetadataKeywordKind(StrVal), StrVal);
490   if (Token.isError())
491     ErrorCallback(Token.location(),
492                   "use of unknown metadata keyword '" + StrVal + "'");
493   return C;
494 }
495 
496 static MIToken::TokenKind symbolToken(char C) {
497   switch (C) {
498   case ',':
499     return MIToken::comma;
500   case '.':
501     return MIToken::dot;
502   case '=':
503     return MIToken::equal;
504   case ':':
505     return MIToken::colon;
506   case '(':
507     return MIToken::lparen;
508   case ')':
509     return MIToken::rparen;
510   case '{':
511     return MIToken::lbrace;
512   case '}':
513     return MIToken::rbrace;
514   case '+':
515     return MIToken::plus;
516   case '-':
517     return MIToken::minus;
518   case '<':
519     return MIToken::less;
520   case '>':
521     return MIToken::greater;
522   default:
523     return MIToken::Error;
524   }
525 }
526 
527 static Cursor maybeLexSymbol(Cursor C, MIToken &Token) {
528   MIToken::TokenKind Kind;
529   unsigned Length = 1;
530   if (C.peek() == ':' && C.peek(1) == ':') {
531     Kind = MIToken::coloncolon;
532     Length = 2;
533   } else
534     Kind = symbolToken(C.peek());
535   if (Kind == MIToken::Error)
536     return None;
537   auto Range = C;
538   C.advance(Length);
539   Token.reset(Kind, Range.upto(C));
540   return C;
541 }
542 
543 static Cursor maybeLexNewline(Cursor C, MIToken &Token) {
544   if (!isNewlineChar(C.peek()))
545     return None;
546   auto Range = C;
547   C.advance();
548   Token.reset(MIToken::Newline, Range.upto(C));
549   return C;
550 }
551 
552 static Cursor maybeLexEscapedIRValue(Cursor C, MIToken &Token,
553                                      ErrorCallbackType ErrorCallback) {
554   if (C.peek() != '`')
555     return None;
556   auto Range = C;
557   C.advance();
558   auto StrRange = C;
559   while (C.peek() != '`') {
560     if (C.isEOF() || isNewlineChar(C.peek())) {
561       ErrorCallback(
562           C.location(),
563           "end of machine instruction reached before the closing '`'");
564       Token.reset(MIToken::Error, Range.remaining());
565       return C;
566     }
567     C.advance();
568   }
569   StringRef Value = StrRange.upto(C);
570   C.advance();
571   Token.reset(MIToken::QuotedIRValue, Range.upto(C)).setStringValue(Value);
572   return C;
573 }
574 
575 StringRef llvm::lexMIToken(StringRef Source, MIToken &Token,
576                            ErrorCallbackType ErrorCallback) {
577   auto C = skipComment(skipWhitespace(Cursor(Source)));
578   if (C.isEOF()) {
579     Token.reset(MIToken::Eof, C.remaining());
580     return C.remaining();
581   }
582 
583   if (Cursor R = maybeLexIntegerOrScalarType(C, Token))
584     return R.remaining();
585   if (Cursor R = maybeLexMachineBasicBlock(C, Token, ErrorCallback))
586     return R.remaining();
587   if (Cursor R = maybeLexIdentifier(C, Token))
588     return R.remaining();
589   if (Cursor R = maybeLexJumpTableIndex(C, Token))
590     return R.remaining();
591   if (Cursor R = maybeLexStackObject(C, Token))
592     return R.remaining();
593   if (Cursor R = maybeLexFixedStackObject(C, Token))
594     return R.remaining();
595   if (Cursor R = maybeLexConstantPoolItem(C, Token))
596     return R.remaining();
597   if (Cursor R = maybeLexSubRegisterIndex(C, Token, ErrorCallback))
598     return R.remaining();
599   if (Cursor R = maybeLexIRBlock(C, Token, ErrorCallback))
600     return R.remaining();
601   if (Cursor R = maybeLexIRValue(C, Token, ErrorCallback))
602     return R.remaining();
603   if (Cursor R = maybeLexRegister(C, Token))
604     return R.remaining();
605   if (Cursor R = maybeLexGlobalValue(C, Token, ErrorCallback))
606     return R.remaining();
607   if (Cursor R = maybeLexExternalSymbol(C, Token, ErrorCallback))
608     return R.remaining();
609   if (Cursor R = maybeLexHexFloatingPointLiteral(C, Token))
610     return R.remaining();
611   if (Cursor R = maybeLexNumericalLiteral(C, Token))
612     return R.remaining();
613   if (Cursor R = maybeLexExlaim(C, Token, ErrorCallback))
614     return R.remaining();
615   if (Cursor R = maybeLexSymbol(C, Token))
616     return R.remaining();
617   if (Cursor R = maybeLexNewline(C, Token))
618     return R.remaining();
619   if (Cursor R = maybeLexEscapedIRValue(C, Token, ErrorCallback))
620     return R.remaining();
621 
622   Token.reset(MIToken::Error, C.remaining());
623   ErrorCallback(C.location(),
624                 Twine("unexpected character '") + Twine(C.peek()) + "'");
625   return C.remaining();
626 }
627