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/StringExtras.h"
16 #include "llvm/ADT/StringSwitch.h"
17 #include "llvm/ADT/Twine.h"
18 #include <cctype>
19 
20 using namespace llvm;
21 
22 namespace {
23 
24 /// This class provides a way to iterate and get characters from the source
25 /// string.
26 class Cursor {
27   const char *Ptr;
28   const char *End;
29 
30 public:
31   Cursor(NoneType) : Ptr(nullptr), End(nullptr) {}
32 
33   explicit Cursor(StringRef Str) {
34     Ptr = Str.data();
35     End = Ptr + Str.size();
36   }
37 
38   bool isEOF() const { return Ptr == End; }
39 
40   char peek(int I = 0) const { return End - Ptr <= I ? 0 : Ptr[I]; }
41 
42   void advance(unsigned I = 1) { Ptr += I; }
43 
44   StringRef remaining() const { return StringRef(Ptr, End - Ptr); }
45 
46   StringRef upto(Cursor C) const {
47     assert(C.Ptr >= Ptr && C.Ptr <= End);
48     return StringRef(Ptr, C.Ptr - Ptr);
49   }
50 
51   StringRef::iterator location() const { return Ptr; }
52 
53   operator bool() const { return Ptr != nullptr; }
54 };
55 
56 } // end anonymous namespace
57 
58 /// Skip the leading whitespace characters and return the updated cursor.
59 static Cursor skipWhitespace(Cursor C) {
60   while (isspace(C.peek()))
61     C.advance();
62   return C;
63 }
64 
65 /// Return true if the given character satisfies the following regular
66 /// expression: [-a-zA-Z$._0-9]
67 static bool isIdentifierChar(char C) {
68   return isalpha(C) || isdigit(C) || C == '_' || C == '-' || C == '.' ||
69          C == '$';
70 }
71 
72 void MIToken::unescapeQuotedStringValue(std::string &Str) const {
73   assert(isStringValueQuoted() && "String value isn't quoted");
74   StringRef Value = Range.drop_front(StringOffset);
75   assert(Value.front() == '"' && Value.back() == '"');
76   Cursor C = Cursor(Value.substr(1, Value.size() - 2));
77 
78   Str.clear();
79   Str.reserve(C.remaining().size());
80   while (!C.isEOF()) {
81     char Char = C.peek();
82     if (Char == '\\') {
83       if (C.peek(1) == '\\') {
84         // Two '\' become one
85         Str += '\\';
86         C.advance(2);
87         continue;
88       }
89       if (isxdigit(C.peek(1)) && isxdigit(C.peek(2))) {
90         Str += hexDigitValue(C.peek(1)) * 16 + hexDigitValue(C.peek(2));
91         C.advance(3);
92         continue;
93       }
94     }
95     Str += Char;
96     C.advance();
97   }
98 }
99 
100 /// Lex a string constant using the following regular expression: \"[^\"]*\"
101 static Cursor lexStringConstant(
102     Cursor C,
103     function_ref<void(StringRef::iterator Loc, const Twine &)> ErrorCallback) {
104   assert(C.peek() == '"');
105   for (C.advance(); C.peek() != '"'; C.advance()) {
106     if (C.isEOF()) {
107       ErrorCallback(
108           C.location(),
109           "end of machine instruction reached before the closing '\"'");
110       return None;
111     }
112   }
113   C.advance();
114   return C;
115 }
116 
117 static MIToken::TokenKind getIdentifierKind(StringRef Identifier) {
118   return StringSwitch<MIToken::TokenKind>(Identifier)
119       .Case("_", MIToken::underscore)
120       .Case("implicit", MIToken::kw_implicit)
121       .Case("implicit-def", MIToken::kw_implicit_define)
122       .Case("dead", MIToken::kw_dead)
123       .Case("killed", MIToken::kw_killed)
124       .Case("undef", MIToken::kw_undef)
125       .Case("frame-setup", MIToken::kw_frame_setup)
126       .Case("debug-location", MIToken::kw_debug_location)
127       .Case(".cfi_offset", MIToken::kw_cfi_offset)
128       .Case(".cfi_def_cfa_register", MIToken::kw_cfi_def_cfa_register)
129       .Case(".cfi_def_cfa_offset", MIToken::kw_cfi_def_cfa_offset)
130       .Default(MIToken::Identifier);
131 }
132 
133 static Cursor maybeLexIdentifier(Cursor C, MIToken &Token) {
134   if (!isalpha(C.peek()) && C.peek() != '_' && C.peek() != '.')
135     return None;
136   auto Range = C;
137   while (isIdentifierChar(C.peek()))
138     C.advance();
139   auto Identifier = Range.upto(C);
140   Token = MIToken(getIdentifierKind(Identifier), Identifier);
141   return C;
142 }
143 
144 static Cursor maybeLexMachineBasicBlock(
145     Cursor C, MIToken &Token,
146     function_ref<void(StringRef::iterator Loc, const Twine &)> ErrorCallback) {
147   if (!C.remaining().startswith("%bb."))
148     return None;
149   auto Range = C;
150   C.advance(4); // Skip '%bb.'
151   if (!isdigit(C.peek())) {
152     Token = MIToken(MIToken::Error, C.remaining());
153     ErrorCallback(C.location(), "expected a number after '%bb.'");
154     return C;
155   }
156   auto NumberRange = C;
157   while (isdigit(C.peek()))
158     C.advance();
159   StringRef Number = NumberRange.upto(C);
160   unsigned StringOffset = 4 + Number.size(); // Drop '%bb.<id>'
161   if (C.peek() == '.') {
162     C.advance(); // Skip '.'
163     ++StringOffset;
164     while (isIdentifierChar(C.peek()))
165       C.advance();
166   }
167   Token = MIToken(MIToken::MachineBasicBlock, Range.upto(C), APSInt(Number),
168                   StringOffset);
169   return C;
170 }
171 
172 static Cursor maybeLexIndex(Cursor C, MIToken &Token, StringRef Rule,
173                             MIToken::TokenKind Kind) {
174   if (!C.remaining().startswith(Rule) || !isdigit(C.peek(Rule.size())))
175     return None;
176   auto Range = C;
177   C.advance(Rule.size());
178   auto NumberRange = C;
179   while (isdigit(C.peek()))
180     C.advance();
181   Token = MIToken(Kind, Range.upto(C), APSInt(NumberRange.upto(C)));
182   return C;
183 }
184 
185 static Cursor maybeLexIndexAndName(Cursor C, MIToken &Token, StringRef Rule,
186                                    MIToken::TokenKind Kind) {
187   if (!C.remaining().startswith(Rule) || !isdigit(C.peek(Rule.size())))
188     return None;
189   auto Range = C;
190   C.advance(Rule.size());
191   auto NumberRange = C;
192   while (isdigit(C.peek()))
193     C.advance();
194   StringRef Number = NumberRange.upto(C);
195   unsigned StringOffset = Rule.size() + Number.size();
196   if (C.peek() == '.') {
197     C.advance();
198     ++StringOffset;
199     while (isIdentifierChar(C.peek()))
200       C.advance();
201   }
202   Token = MIToken(Kind, Range.upto(C), APSInt(Number), StringOffset);
203   return C;
204 }
205 
206 static Cursor maybeLexJumpTableIndex(Cursor C, MIToken &Token) {
207   return maybeLexIndex(C, Token, "%jump-table.", MIToken::JumpTableIndex);
208 }
209 
210 static Cursor maybeLexStackObject(Cursor C, MIToken &Token) {
211   return maybeLexIndexAndName(C, Token, "%stack.", MIToken::StackObject);
212 }
213 
214 static Cursor maybeLexFixedStackObject(Cursor C, MIToken &Token) {
215   return maybeLexIndex(C, Token, "%fixed-stack.", MIToken::FixedStackObject);
216 }
217 
218 static Cursor maybeLexConstantPoolItem(Cursor C, MIToken &Token) {
219   return maybeLexIndex(C, Token, "%const.", MIToken::ConstantPoolItem);
220 }
221 
222 static Cursor maybeLexIRBlock(Cursor C, MIToken &Token) {
223   return maybeLexIndex(C, Token, "%ir-block.", MIToken::IRBlock);
224 }
225 
226 static Cursor lexVirtualRegister(Cursor C, MIToken &Token) {
227   auto Range = C;
228   C.advance(); // Skip '%'
229   auto NumberRange = C;
230   while (isdigit(C.peek()))
231     C.advance();
232   Token = MIToken(MIToken::VirtualRegister, Range.upto(C),
233                   APSInt(NumberRange.upto(C)));
234   return C;
235 }
236 
237 static Cursor maybeLexRegister(Cursor C, MIToken &Token) {
238   if (C.peek() != '%')
239     return None;
240   if (isdigit(C.peek(1)))
241     return lexVirtualRegister(C, Token);
242   auto Range = C;
243   C.advance(); // Skip '%'
244   while (isIdentifierChar(C.peek()))
245     C.advance();
246   Token = MIToken(MIToken::NamedRegister, Range.upto(C),
247                   /*StringOffset=*/1); // Drop the '%'
248   return C;
249 }
250 
251 static Cursor lexName(
252     Cursor C, MIToken &Token, MIToken::TokenKind Type,
253     MIToken::TokenKind QuotedType, unsigned PrefixLength,
254     function_ref<void(StringRef::iterator Loc, const Twine &)> ErrorCallback) {
255   auto Range = C;
256   C.advance(PrefixLength);
257   if (C.peek() == '"') {
258     if (Cursor R = lexStringConstant(C, ErrorCallback)) {
259       Token = MIToken(QuotedType, Range.upto(R), PrefixLength);
260       return R;
261     }
262     Token = MIToken(MIToken::Error, Range.remaining());
263     return Range;
264   }
265   while (isIdentifierChar(C.peek()))
266     C.advance();
267   Token = MIToken(Type, Range.upto(C), PrefixLength);
268   return C;
269 }
270 
271 static Cursor maybeLexGlobalValue(
272     Cursor C, MIToken &Token,
273     function_ref<void(StringRef::iterator Loc, const Twine &)> ErrorCallback) {
274   if (C.peek() != '@')
275     return None;
276   if (!isdigit(C.peek(1)))
277     return lexName(C, Token, MIToken::NamedGlobalValue,
278                    MIToken::QuotedNamedGlobalValue, /*PrefixLength=*/1,
279                    ErrorCallback);
280   auto Range = C;
281   C.advance(1); // Skip the '@'
282   auto NumberRange = C;
283   while (isdigit(C.peek()))
284     C.advance();
285   Token =
286       MIToken(MIToken::GlobalValue, Range.upto(C), APSInt(NumberRange.upto(C)));
287   return C;
288 }
289 
290 static Cursor maybeLexExternalSymbol(
291     Cursor C, MIToken &Token,
292     function_ref<void(StringRef::iterator Loc, const Twine &)> ErrorCallback) {
293   if (C.peek() != '$')
294     return None;
295   return lexName(C, Token, MIToken::ExternalSymbol,
296                  MIToken::QuotedExternalSymbol,
297                  /*PrefixLength=*/1, ErrorCallback);
298 }
299 
300 static Cursor maybeLexIntegerLiteral(Cursor C, MIToken &Token) {
301   if (!isdigit(C.peek()) && (C.peek() != '-' || !isdigit(C.peek(1))))
302     return None;
303   auto Range = C;
304   C.advance();
305   while (isdigit(C.peek()))
306     C.advance();
307   StringRef StrVal = Range.upto(C);
308   Token = MIToken(MIToken::IntegerLiteral, StrVal, APSInt(StrVal));
309   return C;
310 }
311 
312 static MIToken::TokenKind symbolToken(char C) {
313   switch (C) {
314   case ',':
315     return MIToken::comma;
316   case '=':
317     return MIToken::equal;
318   case ':':
319     return MIToken::colon;
320   case '!':
321     return MIToken::exclaim;
322   default:
323     return MIToken::Error;
324   }
325 }
326 
327 static Cursor maybeLexSymbol(Cursor C, MIToken &Token) {
328   auto Kind = symbolToken(C.peek());
329   if (Kind == MIToken::Error)
330     return None;
331   auto Range = C;
332   C.advance();
333   Token = MIToken(Kind, Range.upto(C));
334   return C;
335 }
336 
337 StringRef llvm::lexMIToken(
338     StringRef Source, MIToken &Token,
339     function_ref<void(StringRef::iterator Loc, const Twine &)> ErrorCallback) {
340   auto C = skipWhitespace(Cursor(Source));
341   if (C.isEOF()) {
342     Token = MIToken(MIToken::Eof, C.remaining());
343     return C.remaining();
344   }
345 
346   if (Cursor R = maybeLexIdentifier(C, Token))
347     return R.remaining();
348   if (Cursor R = maybeLexMachineBasicBlock(C, Token, ErrorCallback))
349     return R.remaining();
350   if (Cursor R = maybeLexJumpTableIndex(C, Token))
351     return R.remaining();
352   if (Cursor R = maybeLexStackObject(C, Token))
353     return R.remaining();
354   if (Cursor R = maybeLexFixedStackObject(C, Token))
355     return R.remaining();
356   if (Cursor R = maybeLexConstantPoolItem(C, Token))
357     return R.remaining();
358   if (Cursor R = maybeLexIRBlock(C, Token))
359     return R.remaining();
360   if (Cursor R = maybeLexRegister(C, Token))
361     return R.remaining();
362   if (Cursor R = maybeLexGlobalValue(C, Token, ErrorCallback))
363     return R.remaining();
364   if (Cursor R = maybeLexExternalSymbol(C, Token, ErrorCallback))
365     return R.remaining();
366   if (Cursor R = maybeLexIntegerLiteral(C, Token))
367     return R.remaining();
368   if (Cursor R = maybeLexSymbol(C, Token))
369     return R.remaining();
370 
371   Token = MIToken(MIToken::Error, C.remaining());
372   ErrorCallback(C.location(),
373                 Twine("unexpected character '") + Twine(C.peek()) + "'");
374   return C.remaining();
375 }
376