AsmLexer.cpp revision a78c67e9bbf6ff0253945f3ba5bc178ece76d886 
1//===- AsmLexer.cpp - Lexer for Assembly Files ----------------------------===//
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 class implements the lexer for assembly files.
11//
12//===----------------------------------------------------------------------===//
13
14#include "llvm/MC/MCParser/AsmLexer.h"
15#include "llvm/Support/SMLoc.h"
16#include "llvm/Support/MemoryBuffer.h"
17#include "llvm/MC/MCAsmInfo.h"
18#include <cerrno>
19#include <cstdio>
20#include <cstdlib>
21using namespace llvm;
22
23AsmLexer::AsmLexer(const MCAsmInfo &_MAI) : MAI(_MAI)  {
24  CurBuf = NULL;
25  CurPtr = NULL;
26}
27
28AsmLexer::~AsmLexer() {
29}
30
31void AsmLexer::setBuffer(const MemoryBuffer *buf, const char *ptr) {
32  CurBuf = buf;
33
34  if (ptr)
35    CurPtr = ptr;
36  else
37    CurPtr = CurBuf->getBufferStart();
38
39  TokStart = 0;
40}
41
42/// ReturnError - Set the error to the specified string at the specified
43/// location.  This is defined to always return AsmToken::Error.
44AsmToken AsmLexer::ReturnError(const char *Loc, const std::string &Msg) {
45  SetError(SMLoc::getFromPointer(Loc), Msg);
46
47  return AsmToken(AsmToken::Error, StringRef(Loc, 0));
48}
49
50int AsmLexer::getNextChar() {
51  char CurChar = *CurPtr++;
52  switch (CurChar) {
53  default:
54    return (unsigned char)CurChar;
55  case 0:
56    // A nul character in the stream is either the end of the current buffer or
57    // a random nul in the file.  Disambiguate that here.
58    if (CurPtr-1 != CurBuf->getBufferEnd())
59      return 0;  // Just whitespace.
60
61    // Otherwise, return end of file.
62    --CurPtr;  // Another call to lex will return EOF again.
63    return EOF;
64  }
65}
66
67/// LexIdentifier: [a-zA-Z_.][a-zA-Z0-9_$.@]*
68AsmToken AsmLexer::LexIdentifier() {
69  while (isalnum(*CurPtr) || *CurPtr == '_' || *CurPtr == '$' ||
70         *CurPtr == '.' || *CurPtr == '@')
71    ++CurPtr;
72
73  // Handle . as a special case.
74  if (CurPtr == TokStart+1 && TokStart[0] == '.')
75    return AsmToken(AsmToken::Dot, StringRef(TokStart, 1));
76
77  return AsmToken(AsmToken::Identifier, StringRef(TokStart, CurPtr - TokStart));
78}
79
80/// LexSlash: Slash: /
81///           C-Style Comment: /* ... */
82AsmToken AsmLexer::LexSlash() {
83  switch (*CurPtr) {
84  case '*': break; // C style comment.
85  case '/': return ++CurPtr, LexLineComment();
86  default:  return AsmToken(AsmToken::Slash, StringRef(CurPtr, 1));
87  }
88
89  // C Style comment.
90  ++CurPtr;  // skip the star.
91  while (1) {
92    int CurChar = getNextChar();
93    switch (CurChar) {
94    case EOF:
95      return ReturnError(TokStart, "unterminated comment");
96    case '*':
97      // End of the comment?
98      if (CurPtr[0] != '/') break;
99
100      ++CurPtr;   // End the */.
101      return LexToken();
102    }
103  }
104}
105
106/// LexLineComment: Comment: #[^\n]*
107///                        : //[^\n]*
108AsmToken AsmLexer::LexLineComment() {
109  // FIXME: This is broken if we happen to a comment at the end of a file, which
110  // was .included, and which doesn't end with a newline.
111  int CurChar = getNextChar();
112  while (CurChar != '\n' && CurChar != '\n' && CurChar != EOF)
113    CurChar = getNextChar();
114
115  if (CurChar == EOF)
116    return AsmToken(AsmToken::Eof, StringRef(CurPtr, 0));
117  return AsmToken(AsmToken::EndOfStatement, StringRef(CurPtr, 0));
118}
119
120static void SkipIgnoredIntegerSuffix(const char *&CurPtr) {
121  if (CurPtr[0] == 'L' && CurPtr[1] == 'L')
122    CurPtr += 2;
123  if (CurPtr[0] == 'U' && CurPtr[1] == 'L' && CurPtr[2] == 'L')
124    CurPtr += 3;
125}
126
127
128/// LexDigit: First character is [0-9].
129///   Local Label: [0-9][:]
130///   Forward/Backward Label: [0-9][fb]
131///   Binary integer: 0b[01]+
132///   Octal integer: 0[0-7]+
133///   Hex integer: 0x[0-9a-fA-F]+
134///   Decimal integer: [1-9][0-9]*
135/// TODO: FP literal.
136AsmToken AsmLexer::LexDigit() {
137  // Decimal integer: [1-9][0-9]*
138  if (CurPtr[-1] != '0') {
139    while (isdigit(*CurPtr))
140      ++CurPtr;
141
142    StringRef Result(TokStart, CurPtr - TokStart);
143
144    long long Value;
145    if (Result.getAsInteger(10, Value)) {
146      // We have to handle minint_as_a_positive_value specially, because
147      // - minint_as_a_positive_value = minint and it is valid.
148      if (Result == "9223372036854775808")
149        Value = -9223372036854775808ULL;
150      else
151        return ReturnError(TokStart, "Invalid decimal number");
152    }
153
154    // The darwin/x86 (and x86-64) assembler accepts and ignores ULL and LL
155    // suffixes on integer literals.
156    SkipIgnoredIntegerSuffix(CurPtr);
157
158    return AsmToken(AsmToken::Integer, Result, Value);
159  }
160
161  if (*CurPtr == 'b') {
162    ++CurPtr;
163    // See if we actually have "0b" as part of something like "jmp 0b\n"
164    if (!isdigit(CurPtr[0])) {
165      --CurPtr;
166      StringRef Result(TokStart, CurPtr - TokStart);
167      return AsmToken(AsmToken::Integer, Result, 0);
168    }
169    const char *NumStart = CurPtr;
170    while (CurPtr[0] == '0' || CurPtr[0] == '1')
171      ++CurPtr;
172
173    // Requires at least one binary digit.
174    if (CurPtr == NumStart)
175      return ReturnError(TokStart, "Invalid binary number");
176
177    StringRef Result(TokStart, CurPtr - TokStart);
178
179    long long Value;
180    if (Result.substr(2).getAsInteger(2, Value))
181      return ReturnError(TokStart, "Invalid binary number");
182
183    // The darwin/x86 (and x86-64) assembler accepts and ignores ULL and LL
184    // suffixes on integer literals.
185    SkipIgnoredIntegerSuffix(CurPtr);
186
187    return AsmToken(AsmToken::Integer, Result, Value);
188  }
189
190  if (*CurPtr == 'x') {
191    ++CurPtr;
192    const char *NumStart = CurPtr;
193    while (isxdigit(CurPtr[0]))
194      ++CurPtr;
195
196    // Requires at least one hex digit.
197    if (CurPtr == NumStart)
198      return ReturnError(CurPtr-2, "Invalid hexadecimal number");
199
200    unsigned long long Result;
201    if (StringRef(TokStart, CurPtr - TokStart).getAsInteger(0, Result))
202      return ReturnError(TokStart, "Invalid hexadecimal number");
203
204    // The darwin/x86 (and x86-64) assembler accepts and ignores ULL and LL
205    // suffixes on integer literals.
206    SkipIgnoredIntegerSuffix(CurPtr);
207
208    return AsmToken(AsmToken::Integer, StringRef(TokStart, CurPtr - TokStart),
209                    (int64_t)Result);
210  }
211
212  // Must be an octal number, it starts with 0.
213  while (*CurPtr >= '0' && *CurPtr <= '7')
214    ++CurPtr;
215
216  StringRef Result(TokStart, CurPtr - TokStart);
217  long long Value;
218  if (Result.getAsInteger(8, Value))
219    return ReturnError(TokStart, "Invalid octal number");
220
221  // The darwin/x86 (and x86-64) assembler accepts and ignores ULL and LL
222  // suffixes on integer literals.
223  SkipIgnoredIntegerSuffix(CurPtr);
224
225  return AsmToken(AsmToken::Integer, Result, Value);
226}
227
228/// LexQuote: String: "..."
229AsmToken AsmLexer::LexQuote() {
230  int CurChar = getNextChar();
231  // TODO: does gas allow multiline string constants?
232  while (CurChar != '"') {
233    if (CurChar == '\\') {
234      // Allow \", etc.
235      CurChar = getNextChar();
236    }
237
238    if (CurChar == EOF)
239      return ReturnError(TokStart, "unterminated string constant");
240
241    CurChar = getNextChar();
242  }
243
244  return AsmToken(AsmToken::String, StringRef(TokStart, CurPtr - TokStart));
245}
246
247StringRef AsmLexer::LexUntilEndOfStatement() {
248  TokStart = CurPtr;
249
250  while (!isAtStartOfComment(*CurPtr) && // Start of line comment.
251          *CurPtr != ';' &&  // End of statement marker.
252         *CurPtr != '\n' &&
253         *CurPtr != '\r' &&
254         (*CurPtr != 0 || CurPtr != CurBuf->getBufferEnd())) {
255    ++CurPtr;
256  }
257  return StringRef(TokStart, CurPtr-TokStart);
258}
259
260bool AsmLexer::isAtStartOfComment(char Char) {
261  // FIXME: This won't work for multi-character comment indicators like "//".
262  return Char == *MAI.getCommentString();
263}
264
265AsmToken AsmLexer::LexToken() {
266  TokStart = CurPtr;
267  // This always consumes at least one character.
268  int CurChar = getNextChar();
269
270  if (isAtStartOfComment(CurChar))
271    return LexLineComment();
272
273  switch (CurChar) {
274  default:
275    // Handle identifier: [a-zA-Z_.][a-zA-Z0-9_$.@]*
276    if (isalpha(CurChar) || CurChar == '_' || CurChar == '.')
277      return LexIdentifier();
278
279    // Unknown character, emit an error.
280    return ReturnError(TokStart, "invalid character in input");
281  case EOF: return AsmToken(AsmToken::Eof, StringRef(TokStart, 0));
282  case 0:
283  case ' ':
284  case '\t':
285    // Ignore whitespace.
286    return LexToken();
287  case '\n': // FALL THROUGH.
288  case '\r': // FALL THROUGH.
289  case ';': return AsmToken(AsmToken::EndOfStatement, StringRef(TokStart, 1));
290  case ':': return AsmToken(AsmToken::Colon, StringRef(TokStart, 1));
291  case '+': return AsmToken(AsmToken::Plus, StringRef(TokStart, 1));
292  case '-': return AsmToken(AsmToken::Minus, StringRef(TokStart, 1));
293  case '~': return AsmToken(AsmToken::Tilde, StringRef(TokStart, 1));
294  case '(': return AsmToken(AsmToken::LParen, StringRef(TokStart, 1));
295  case ')': return AsmToken(AsmToken::RParen, StringRef(TokStart, 1));
296  case '[': return AsmToken(AsmToken::LBrac, StringRef(TokStart, 1));
297  case ']': return AsmToken(AsmToken::RBrac, StringRef(TokStart, 1));
298  case '{': return AsmToken(AsmToken::LCurly, StringRef(TokStart, 1));
299  case '}': return AsmToken(AsmToken::RCurly, StringRef(TokStart, 1));
300  case '*': return AsmToken(AsmToken::Star, StringRef(TokStart, 1));
301  case ',': return AsmToken(AsmToken::Comma, StringRef(TokStart, 1));
302  case '$': return AsmToken(AsmToken::Dollar, StringRef(TokStart, 1));
303  case '@': return AsmToken(AsmToken::At, StringRef(TokStart, 1));
304  case '=':
305    if (*CurPtr == '=')
306      return ++CurPtr, AsmToken(AsmToken::EqualEqual, StringRef(TokStart, 2));
307    return AsmToken(AsmToken::Equal, StringRef(TokStart, 1));
308  case '|':
309    if (*CurPtr == '|')
310      return ++CurPtr, AsmToken(AsmToken::PipePipe, StringRef(TokStart, 2));
311    return AsmToken(AsmToken::Pipe, StringRef(TokStart, 1));
312  case '^': return AsmToken(AsmToken::Caret, StringRef(TokStart, 1));
313  case '&':
314    if (*CurPtr == '&')
315      return ++CurPtr, AsmToken(AsmToken::AmpAmp, StringRef(TokStart, 2));
316    return AsmToken(AsmToken::Amp, StringRef(TokStart, 1));
317  case '!':
318    if (*CurPtr == '=')
319      return ++CurPtr, AsmToken(AsmToken::ExclaimEqual, StringRef(TokStart, 2));
320    return AsmToken(AsmToken::Exclaim, StringRef(TokStart, 1));
321  case '%': return AsmToken(AsmToken::Percent, StringRef(TokStart, 1));
322  case '/': return LexSlash();
323  case '#': return AsmToken(AsmToken::Hash, StringRef(TokStart, 1));
324  case '"': return LexQuote();
325  case '0': case '1': case '2': case '3': case '4':
326  case '5': case '6': case '7': case '8': case '9':
327    return LexDigit();
328  case '<':
329    switch (*CurPtr) {
330    case '<': return ++CurPtr, AsmToken(AsmToken::LessLess,
331                                        StringRef(TokStart, 2));
332    case '=': return ++CurPtr, AsmToken(AsmToken::LessEqual,
333                                        StringRef(TokStart, 2));
334    case '>': return ++CurPtr, AsmToken(AsmToken::LessGreater,
335                                        StringRef(TokStart, 2));
336    default: return AsmToken(AsmToken::Less, StringRef(TokStart, 1));
337    }
338  case '>':
339    switch (*CurPtr) {
340    case '>': return ++CurPtr, AsmToken(AsmToken::GreaterGreater,
341                                        StringRef(TokStart, 2));
342    case '=': return ++CurPtr, AsmToken(AsmToken::GreaterEqual,
343                                        StringRef(TokStart, 2));
344    default: return AsmToken(AsmToken::Greater, StringRef(TokStart, 1));
345    }
346
347  // TODO: Quoted identifiers (objc methods etc)
348  // local labels: [0-9][:]
349  // Forward/backward labels: [0-9][fb]
350  // Integers, fp constants, character constants.
351  }
352}
353