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 Cursor lexName(
118     Cursor C, MIToken &Token, MIToken::TokenKind Type,
119     MIToken::TokenKind QuotedType, unsigned PrefixLength,
120     function_ref<void(StringRef::iterator Loc, const Twine &)> ErrorCallback) {
121   auto Range = C;
122   C.advance(PrefixLength);
123   if (C.peek() == '"') {
124     if (Cursor R = lexStringConstant(C, ErrorCallback)) {
125       Token = MIToken(QuotedType, Range.upto(R), PrefixLength);
126       return R;
127     }
128     Token = MIToken(MIToken::Error, Range.remaining());
129     return Range;
130   }
131   while (isIdentifierChar(C.peek()))
132     C.advance();
133   Token = MIToken(Type, Range.upto(C), PrefixLength);
134   return C;
135 }
136 
137 static MIToken::TokenKind getIdentifierKind(StringRef Identifier) {
138   return StringSwitch<MIToken::TokenKind>(Identifier)
139       .Case("_", MIToken::underscore)
140       .Case("implicit", MIToken::kw_implicit)
141       .Case("implicit-def", MIToken::kw_implicit_define)
142       .Case("dead", MIToken::kw_dead)
143       .Case("killed", MIToken::kw_killed)
144       .Case("undef", MIToken::kw_undef)
145       .Case("frame-setup", MIToken::kw_frame_setup)
146       .Case("debug-location", MIToken::kw_debug_location)
147       .Case(".cfi_offset", MIToken::kw_cfi_offset)
148       .Case(".cfi_def_cfa_register", MIToken::kw_cfi_def_cfa_register)
149       .Case(".cfi_def_cfa_offset", MIToken::kw_cfi_def_cfa_offset)
150       .Case("blockaddress", MIToken::kw_blockaddress)
151       .Case("target-index", MIToken::kw_target_index)
152       .Default(MIToken::Identifier);
153 }
154 
155 static Cursor maybeLexIdentifier(Cursor C, MIToken &Token) {
156   if (!isalpha(C.peek()) && C.peek() != '_' && C.peek() != '.')
157     return None;
158   auto Range = C;
159   while (isIdentifierChar(C.peek()))
160     C.advance();
161   auto Identifier = Range.upto(C);
162   Token = MIToken(getIdentifierKind(Identifier), Identifier);
163   return C;
164 }
165 
166 static Cursor maybeLexMachineBasicBlock(
167     Cursor C, MIToken &Token,
168     function_ref<void(StringRef::iterator Loc, const Twine &)> ErrorCallback) {
169   if (!C.remaining().startswith("%bb."))
170     return None;
171   auto Range = C;
172   C.advance(4); // Skip '%bb.'
173   if (!isdigit(C.peek())) {
174     Token = MIToken(MIToken::Error, C.remaining());
175     ErrorCallback(C.location(), "expected a number after '%bb.'");
176     return C;
177   }
178   auto NumberRange = C;
179   while (isdigit(C.peek()))
180     C.advance();
181   StringRef Number = NumberRange.upto(C);
182   unsigned StringOffset = 4 + Number.size(); // Drop '%bb.<id>'
183   if (C.peek() == '.') {
184     C.advance(); // Skip '.'
185     ++StringOffset;
186     while (isIdentifierChar(C.peek()))
187       C.advance();
188   }
189   Token = MIToken(MIToken::MachineBasicBlock, Range.upto(C), APSInt(Number),
190                   StringOffset);
191   return C;
192 }
193 
194 static Cursor maybeLexIndex(Cursor C, MIToken &Token, StringRef Rule,
195                             MIToken::TokenKind Kind) {
196   if (!C.remaining().startswith(Rule) || !isdigit(C.peek(Rule.size())))
197     return None;
198   auto Range = C;
199   C.advance(Rule.size());
200   auto NumberRange = C;
201   while (isdigit(C.peek()))
202     C.advance();
203   Token = MIToken(Kind, Range.upto(C), APSInt(NumberRange.upto(C)));
204   return C;
205 }
206 
207 static Cursor maybeLexIndexAndName(Cursor C, MIToken &Token, StringRef Rule,
208                                    MIToken::TokenKind Kind) {
209   if (!C.remaining().startswith(Rule) || !isdigit(C.peek(Rule.size())))
210     return None;
211   auto Range = C;
212   C.advance(Rule.size());
213   auto NumberRange = C;
214   while (isdigit(C.peek()))
215     C.advance();
216   StringRef Number = NumberRange.upto(C);
217   unsigned StringOffset = Rule.size() + Number.size();
218   if (C.peek() == '.') {
219     C.advance();
220     ++StringOffset;
221     while (isIdentifierChar(C.peek()))
222       C.advance();
223   }
224   Token = MIToken(Kind, Range.upto(C), APSInt(Number), StringOffset);
225   return C;
226 }
227 
228 static Cursor maybeLexJumpTableIndex(Cursor C, MIToken &Token) {
229   return maybeLexIndex(C, Token, "%jump-table.", MIToken::JumpTableIndex);
230 }
231 
232 static Cursor maybeLexStackObject(Cursor C, MIToken &Token) {
233   return maybeLexIndexAndName(C, Token, "%stack.", MIToken::StackObject);
234 }
235 
236 static Cursor maybeLexFixedStackObject(Cursor C, MIToken &Token) {
237   return maybeLexIndex(C, Token, "%fixed-stack.", MIToken::FixedStackObject);
238 }
239 
240 static Cursor maybeLexConstantPoolItem(Cursor C, MIToken &Token) {
241   return maybeLexIndex(C, Token, "%const.", MIToken::ConstantPoolItem);
242 }
243 
244 static Cursor maybeLexIRBlock(
245     Cursor C, MIToken &Token,
246     function_ref<void(StringRef::iterator Loc, const Twine &)> ErrorCallback) {
247   const StringRef Rule = "%ir-block.";
248   if (!C.remaining().startswith(Rule))
249     return None;
250   if (isdigit(C.peek(Rule.size())))
251     return maybeLexIndex(C, Token, Rule, MIToken::IRBlock);
252   return lexName(C, Token, MIToken::NamedIRBlock, MIToken::QuotedNamedIRBlock,
253                  Rule.size(), ErrorCallback);
254 }
255 
256 static Cursor lexVirtualRegister(Cursor C, MIToken &Token) {
257   auto Range = C;
258   C.advance(); // Skip '%'
259   auto NumberRange = C;
260   while (isdigit(C.peek()))
261     C.advance();
262   Token = MIToken(MIToken::VirtualRegister, Range.upto(C),
263                   APSInt(NumberRange.upto(C)));
264   return C;
265 }
266 
267 static Cursor maybeLexRegister(Cursor C, MIToken &Token) {
268   if (C.peek() != '%')
269     return None;
270   if (isdigit(C.peek(1)))
271     return lexVirtualRegister(C, Token);
272   auto Range = C;
273   C.advance(); // Skip '%'
274   while (isIdentifierChar(C.peek()))
275     C.advance();
276   Token = MIToken(MIToken::NamedRegister, Range.upto(C),
277                   /*StringOffset=*/1); // Drop the '%'
278   return C;
279 }
280 
281 static Cursor maybeLexGlobalValue(
282     Cursor C, MIToken &Token,
283     function_ref<void(StringRef::iterator Loc, const Twine &)> ErrorCallback) {
284   if (C.peek() != '@')
285     return None;
286   if (!isdigit(C.peek(1)))
287     return lexName(C, Token, MIToken::NamedGlobalValue,
288                    MIToken::QuotedNamedGlobalValue, /*PrefixLength=*/1,
289                    ErrorCallback);
290   auto Range = C;
291   C.advance(1); // Skip the '@'
292   auto NumberRange = C;
293   while (isdigit(C.peek()))
294     C.advance();
295   Token =
296       MIToken(MIToken::GlobalValue, Range.upto(C), APSInt(NumberRange.upto(C)));
297   return C;
298 }
299 
300 static Cursor maybeLexExternalSymbol(
301     Cursor C, MIToken &Token,
302     function_ref<void(StringRef::iterator Loc, const Twine &)> ErrorCallback) {
303   if (C.peek() != '$')
304     return None;
305   return lexName(C, Token, MIToken::ExternalSymbol,
306                  MIToken::QuotedExternalSymbol,
307                  /*PrefixLength=*/1, ErrorCallback);
308 }
309 
310 static Cursor maybeLexIntegerLiteral(Cursor C, MIToken &Token) {
311   if (!isdigit(C.peek()) && (C.peek() != '-' || !isdigit(C.peek(1))))
312     return None;
313   auto Range = C;
314   C.advance();
315   while (isdigit(C.peek()))
316     C.advance();
317   StringRef StrVal = Range.upto(C);
318   Token = MIToken(MIToken::IntegerLiteral, StrVal, APSInt(StrVal));
319   return C;
320 }
321 
322 static MIToken::TokenKind symbolToken(char C) {
323   switch (C) {
324   case ',':
325     return MIToken::comma;
326   case '=':
327     return MIToken::equal;
328   case ':':
329     return MIToken::colon;
330   case '!':
331     return MIToken::exclaim;
332   case '(':
333     return MIToken::lparen;
334   case ')':
335     return MIToken::rparen;
336   default:
337     return MIToken::Error;
338   }
339 }
340 
341 static Cursor maybeLexSymbol(Cursor C, MIToken &Token) {
342   auto Kind = symbolToken(C.peek());
343   if (Kind == MIToken::Error)
344     return None;
345   auto Range = C;
346   C.advance();
347   Token = MIToken(Kind, Range.upto(C));
348   return C;
349 }
350 
351 StringRef llvm::lexMIToken(
352     StringRef Source, MIToken &Token,
353     function_ref<void(StringRef::iterator Loc, const Twine &)> ErrorCallback) {
354   auto C = skipWhitespace(Cursor(Source));
355   if (C.isEOF()) {
356     Token = MIToken(MIToken::Eof, C.remaining());
357     return C.remaining();
358   }
359 
360   if (Cursor R = maybeLexIdentifier(C, Token))
361     return R.remaining();
362   if (Cursor R = maybeLexMachineBasicBlock(C, Token, ErrorCallback))
363     return R.remaining();
364   if (Cursor R = maybeLexJumpTableIndex(C, Token))
365     return R.remaining();
366   if (Cursor R = maybeLexStackObject(C, Token))
367     return R.remaining();
368   if (Cursor R = maybeLexFixedStackObject(C, Token))
369     return R.remaining();
370   if (Cursor R = maybeLexConstantPoolItem(C, Token))
371     return R.remaining();
372   if (Cursor R = maybeLexIRBlock(C, Token, ErrorCallback))
373     return R.remaining();
374   if (Cursor R = maybeLexRegister(C, Token))
375     return R.remaining();
376   if (Cursor R = maybeLexGlobalValue(C, Token, ErrorCallback))
377     return R.remaining();
378   if (Cursor R = maybeLexExternalSymbol(C, Token, ErrorCallback))
379     return R.remaining();
380   if (Cursor R = maybeLexIntegerLiteral(C, Token))
381     return R.remaining();
382   if (Cursor R = maybeLexSymbol(C, Token))
383     return R.remaining();
384 
385   Token = MIToken(MIToken::Error, C.remaining());
386   ErrorCallback(C.location(),
387                 Twine("unexpected character '") + Twine(C.peek()) + "'");
388   return C.remaining();
389 }
390