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      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 <cctype>
     19 #include <cerrno>
     20 #include <cstdio>
     21 #include <cstdlib>
     22 using namespace llvm;
     23 
     24 AsmLexer::AsmLexer(const MCAsmInfo &_MAI) : MAI(_MAI)  {
     25   CurBuf = NULL;
     26   CurPtr = NULL;
     27   isAtStartOfLine = true;
     28 }
     29 
     30 AsmLexer::~AsmLexer() {
     31 }
     32 
     33 void AsmLexer::setBuffer(const MemoryBuffer *buf, const char *ptr) {
     34   CurBuf = buf;
     35 
     36   if (ptr)
     37     CurPtr = ptr;
     38   else
     39     CurPtr = CurBuf->getBufferStart();
     40 
     41   TokStart = 0;
     42 }
     43 
     44 /// ReturnError - Set the error to the specified string at the specified
     45 /// location.  This is defined to always return AsmToken::Error.
     46 AsmToken AsmLexer::ReturnError(const char *Loc, const std::string &Msg) {
     47   SetError(SMLoc::getFromPointer(Loc), Msg);
     48 
     49   return AsmToken(AsmToken::Error, StringRef(Loc, 0));
     50 }
     51 
     52 int AsmLexer::getNextChar() {
     53   char CurChar = *CurPtr++;
     54   switch (CurChar) {
     55   default:
     56     return (unsigned char)CurChar;
     57   case 0:
     58     // A nul character in the stream is either the end of the current buffer or
     59     // a random nul in the file.  Disambiguate that here.
     60     if (CurPtr-1 != CurBuf->getBufferEnd())
     61       return 0;  // Just whitespace.
     62 
     63     // Otherwise, return end of file.
     64     --CurPtr;  // Another call to lex will return EOF again.
     65     return EOF;
     66   }
     67 }
     68 
     69 /// LexFloatLiteral: [0-9]*[.][0-9]*([eE][+-]?[0-9]*)?
     70 ///
     71 /// The leading integral digit sequence and dot should have already been
     72 /// consumed, some or all of the fractional digit sequence *can* have been
     73 /// consumed.
     74 AsmToken AsmLexer::LexFloatLiteral() {
     75   // Skip the fractional digit sequence.
     76   while (isdigit(*CurPtr))
     77     ++CurPtr;
     78 
     79   // Check for exponent; we intentionally accept a slighlty wider set of
     80   // literals here and rely on the upstream client to reject invalid ones (e.g.,
     81   // "1e+").
     82   if (*CurPtr == 'e' || *CurPtr == 'E') {
     83     ++CurPtr;
     84     if (*CurPtr == '-' || *CurPtr == '+')
     85       ++CurPtr;
     86     while (isdigit(*CurPtr))
     87       ++CurPtr;
     88   }
     89 
     90   return AsmToken(AsmToken::Real,
     91                   StringRef(TokStart, CurPtr - TokStart));
     92 }
     93 
     94 /// LexIdentifier: [a-zA-Z_.][a-zA-Z0-9_$.@]*
     95 static bool IsIdentifierChar(char c) {
     96   return isalnum(c) || c == '_' || c == '$' || c == '.' || c == '@';
     97 }
     98 AsmToken AsmLexer::LexIdentifier() {
     99   // Check for floating point literals.
    100   if (CurPtr[-1] == '.' && isdigit(*CurPtr)) {
    101     // Disambiguate a .1243foo identifier from a floating literal.
    102     while (isdigit(*CurPtr))
    103       ++CurPtr;
    104     if (*CurPtr == 'e' || *CurPtr == 'E' || !IsIdentifierChar(*CurPtr))
    105       return LexFloatLiteral();
    106   }
    107 
    108   while (IsIdentifierChar(*CurPtr))
    109     ++CurPtr;
    110 
    111   // Handle . as a special case.
    112   if (CurPtr == TokStart+1 && TokStart[0] == '.')
    113     return AsmToken(AsmToken::Dot, StringRef(TokStart, 1));
    114 
    115   return AsmToken(AsmToken::Identifier, StringRef(TokStart, CurPtr - TokStart));
    116 }
    117 
    118 /// LexSlash: Slash: /
    119 ///           C-Style Comment: /* ... */
    120 AsmToken AsmLexer::LexSlash() {
    121   switch (*CurPtr) {
    122   case '*': break; // C style comment.
    123   case '/': return ++CurPtr, LexLineComment();
    124   default:  return AsmToken(AsmToken::Slash, StringRef(CurPtr-1, 1));
    125   }
    126 
    127   // C Style comment.
    128   ++CurPtr;  // skip the star.
    129   while (1) {
    130     int CurChar = getNextChar();
    131     switch (CurChar) {
    132     case EOF:
    133       return ReturnError(TokStart, "unterminated comment");
    134     case '*':
    135       // End of the comment?
    136       if (CurPtr[0] != '/') break;
    137 
    138       ++CurPtr;   // End the */.
    139       return LexToken();
    140     }
    141   }
    142 }
    143 
    144 /// LexLineComment: Comment: #[^\n]*
    145 ///                        : //[^\n]*
    146 AsmToken AsmLexer::LexLineComment() {
    147   // FIXME: This is broken if we happen to a comment at the end of a file, which
    148   // was .included, and which doesn't end with a newline.
    149   int CurChar = getNextChar();
    150   while (CurChar != '\n' && CurChar != '\r' && CurChar != EOF)
    151     CurChar = getNextChar();
    152 
    153   if (CurChar == EOF)
    154     return AsmToken(AsmToken::Eof, StringRef(CurPtr, 0));
    155   return AsmToken(AsmToken::EndOfStatement, StringRef(CurPtr, 0));
    156 }
    157 
    158 static void SkipIgnoredIntegerSuffix(const char *&CurPtr) {
    159   if (CurPtr[0] == 'L' && CurPtr[1] == 'L')
    160     CurPtr += 2;
    161   if (CurPtr[0] == 'U' && CurPtr[1] == 'L' && CurPtr[2] == 'L')
    162     CurPtr += 3;
    163 }
    164 
    165 /// LexDigit: First character is [0-9].
    166 ///   Local Label: [0-9][:]
    167 ///   Forward/Backward Label: [0-9][fb]
    168 ///   Binary integer: 0b[01]+
    169 ///   Octal integer: 0[0-7]+
    170 ///   Hex integer: 0x[0-9a-fA-F]+
    171 ///   Decimal integer: [1-9][0-9]*
    172 AsmToken AsmLexer::LexDigit() {
    173   // Decimal integer: [1-9][0-9]*
    174   if (CurPtr[-1] != '0' || CurPtr[0] == '.') {
    175     while (isdigit(*CurPtr))
    176       ++CurPtr;
    177 
    178     // Check for floating point literals.
    179     if (*CurPtr == '.' || *CurPtr == 'e') {
    180       ++CurPtr;
    181       return LexFloatLiteral();
    182     }
    183 
    184     StringRef Result(TokStart, CurPtr - TokStart);
    185 
    186     long long Value;
    187     if (Result.getAsInteger(10, Value)) {
    188       // Allow positive values that are too large to fit into a signed 64-bit
    189       // integer, but that do fit in an unsigned one, we just convert them over.
    190       unsigned long long UValue;
    191       if (Result.getAsInteger(10, UValue))
    192         return ReturnError(TokStart, "invalid decimal number");
    193       Value = (long long)UValue;
    194     }
    195 
    196     // The darwin/x86 (and x86-64) assembler accepts and ignores ULL and LL
    197     // suffixes on integer literals.
    198     SkipIgnoredIntegerSuffix(CurPtr);
    199 
    200     return AsmToken(AsmToken::Integer, Result, Value);
    201   }
    202 
    203   if (*CurPtr == 'b') {
    204     ++CurPtr;
    205     // See if we actually have "0b" as part of something like "jmp 0b\n"
    206     if (!isdigit(CurPtr[0])) {
    207       --CurPtr;
    208       StringRef Result(TokStart, CurPtr - TokStart);
    209       return AsmToken(AsmToken::Integer, Result, 0);
    210     }
    211     const char *NumStart = CurPtr;
    212     while (CurPtr[0] == '0' || CurPtr[0] == '1')
    213       ++CurPtr;
    214 
    215     // Requires at least one binary digit.
    216     if (CurPtr == NumStart)
    217       return ReturnError(TokStart, "invalid binary number");
    218 
    219     StringRef Result(TokStart, CurPtr - TokStart);
    220 
    221     long long Value;
    222     if (Result.substr(2).getAsInteger(2, Value))
    223       return ReturnError(TokStart, "invalid binary number");
    224 
    225     // The darwin/x86 (and x86-64) assembler accepts and ignores ULL and LL
    226     // suffixes on integer literals.
    227     SkipIgnoredIntegerSuffix(CurPtr);
    228 
    229     return AsmToken(AsmToken::Integer, Result, Value);
    230   }
    231 
    232   if (*CurPtr == 'x') {
    233     ++CurPtr;
    234     const char *NumStart = CurPtr;
    235     while (isxdigit(CurPtr[0]))
    236       ++CurPtr;
    237 
    238     // Requires at least one hex digit.
    239     if (CurPtr == NumStart)
    240       return ReturnError(CurPtr-2, "invalid hexadecimal number");
    241 
    242     unsigned long long Result;
    243     if (StringRef(TokStart, CurPtr - TokStart).getAsInteger(0, Result))
    244       return ReturnError(TokStart, "invalid hexadecimal number");
    245 
    246     // The darwin/x86 (and x86-64) assembler accepts and ignores ULL and LL
    247     // suffixes on integer literals.
    248     SkipIgnoredIntegerSuffix(CurPtr);
    249 
    250     return AsmToken(AsmToken::Integer, StringRef(TokStart, CurPtr - TokStart),
    251                     (int64_t)Result);
    252   }
    253 
    254   // Must be an octal number, it starts with 0.
    255   while (*CurPtr >= '0' && *CurPtr <= '9')
    256     ++CurPtr;
    257 
    258   StringRef Result(TokStart, CurPtr - TokStart);
    259   long long Value;
    260   if (Result.getAsInteger(8, Value))
    261     return ReturnError(TokStart, "invalid octal number");
    262 
    263   // The darwin/x86 (and x86-64) assembler accepts and ignores ULL and LL
    264   // suffixes on integer literals.
    265   SkipIgnoredIntegerSuffix(CurPtr);
    266 
    267   return AsmToken(AsmToken::Integer, Result, Value);
    268 }
    269 
    270 /// LexSingleQuote: Integer: 'b'
    271 AsmToken AsmLexer::LexSingleQuote() {
    272   int CurChar = getNextChar();
    273 
    274   if (CurChar == '\\')
    275     CurChar = getNextChar();
    276 
    277   if (CurChar == EOF)
    278     return ReturnError(TokStart, "unterminated single quote");
    279 
    280   CurChar = getNextChar();
    281 
    282   if (CurChar != '\'')
    283     return ReturnError(TokStart, "single quote way too long");
    284 
    285   // The idea here being that 'c' is basically just an integral
    286   // constant.
    287   StringRef Res = StringRef(TokStart,CurPtr - TokStart);
    288   long long Value;
    289 
    290   if (Res.startswith("\'\\")) {
    291     char theChar = Res[2];
    292     switch (theChar) {
    293       default: Value = theChar; break;
    294       case '\'': Value = '\''; break;
    295       case 't': Value = '\t'; break;
    296       case 'n': Value = '\n'; break;
    297       case 'b': Value = '\b'; break;
    298     }
    299   } else
    300     Value = TokStart[1];
    301 
    302   return AsmToken(AsmToken::Integer, Res, Value);
    303 }
    304 
    305 
    306 /// LexQuote: String: "..."
    307 AsmToken AsmLexer::LexQuote() {
    308   int CurChar = getNextChar();
    309   // TODO: does gas allow multiline string constants?
    310   while (CurChar != '"') {
    311     if (CurChar == '\\') {
    312       // Allow \", etc.
    313       CurChar = getNextChar();
    314     }
    315 
    316     if (CurChar == EOF)
    317       return ReturnError(TokStart, "unterminated string constant");
    318 
    319     CurChar = getNextChar();
    320   }
    321 
    322   return AsmToken(AsmToken::String, StringRef(TokStart, CurPtr - TokStart));
    323 }
    324 
    325 StringRef AsmLexer::LexUntilEndOfStatement() {
    326   TokStart = CurPtr;
    327 
    328   while (!isAtStartOfComment(*CurPtr) &&    // Start of line comment.
    329          !isAtStatementSeparator(CurPtr) && // End of statement marker.
    330          *CurPtr != '\n' &&
    331          *CurPtr != '\r' &&
    332          (*CurPtr != 0 || CurPtr != CurBuf->getBufferEnd())) {
    333     ++CurPtr;
    334   }
    335   return StringRef(TokStart, CurPtr-TokStart);
    336 }
    337 
    338 StringRef AsmLexer::LexUntilEndOfLine() {
    339   TokStart = CurPtr;
    340 
    341   while (*CurPtr != '\n' &&
    342          *CurPtr != '\r' &&
    343          (*CurPtr != 0 || CurPtr != CurBuf->getBufferEnd())) {
    344     ++CurPtr;
    345   }
    346   return StringRef(TokStart, CurPtr-TokStart);
    347 }
    348 
    349 bool AsmLexer::isAtStartOfComment(char Char) {
    350   // FIXME: This won't work for multi-character comment indicators like "//".
    351   return Char == *MAI.getCommentString();
    352 }
    353 
    354 bool AsmLexer::isAtStatementSeparator(const char *Ptr) {
    355   return strncmp(Ptr, MAI.getSeparatorString(),
    356                  strlen(MAI.getSeparatorString())) == 0;
    357 }
    358 
    359 AsmToken AsmLexer::LexToken() {
    360   TokStart = CurPtr;
    361   // This always consumes at least one character.
    362   int CurChar = getNextChar();
    363 
    364   if (isAtStartOfComment(CurChar)) {
    365     // If this comment starts with a '#', then return the Hash token and let
    366     // the assembler parser see if it can be parsed as a cpp line filename
    367     // comment. We do this only if we are at the start of a line.
    368     if (CurChar == '#' && isAtStartOfLine)
    369       return AsmToken(AsmToken::Hash, StringRef(TokStart, 1));
    370     isAtStartOfLine = true;
    371     return LexLineComment();
    372   }
    373   if (isAtStatementSeparator(TokStart)) {
    374     CurPtr += strlen(MAI.getSeparatorString()) - 1;
    375     return AsmToken(AsmToken::EndOfStatement,
    376                     StringRef(TokStart, strlen(MAI.getSeparatorString())));
    377   }
    378 
    379   // If we're missing a newline at EOF, make sure we still get an
    380   // EndOfStatement token before the Eof token.
    381   if (CurChar == EOF && !isAtStartOfLine) {
    382     isAtStartOfLine = true;
    383     return AsmToken(AsmToken::EndOfStatement, StringRef(TokStart, 1));
    384   }
    385 
    386   isAtStartOfLine = false;
    387   switch (CurChar) {
    388   default:
    389     // Handle identifier: [a-zA-Z_.][a-zA-Z0-9_$.@]*
    390     if (isalpha(CurChar) || CurChar == '_' || CurChar == '.')
    391       return LexIdentifier();
    392 
    393     // Unknown character, emit an error.
    394     return ReturnError(TokStart, "invalid character in input");
    395   case EOF: return AsmToken(AsmToken::Eof, StringRef(TokStart, 0));
    396   case 0:
    397   case ' ':
    398   case '\t':
    399     // Ignore whitespace.
    400     return LexToken();
    401   case '\n': // FALL THROUGH.
    402   case '\r':
    403     isAtStartOfLine = true;
    404     return AsmToken(AsmToken::EndOfStatement, StringRef(TokStart, 1));
    405   case ':': return AsmToken(AsmToken::Colon, StringRef(TokStart, 1));
    406   case '+': return AsmToken(AsmToken::Plus, StringRef(TokStart, 1));
    407   case '-': return AsmToken(AsmToken::Minus, StringRef(TokStart, 1));
    408   case '~': return AsmToken(AsmToken::Tilde, StringRef(TokStart, 1));
    409   case '(': return AsmToken(AsmToken::LParen, StringRef(TokStart, 1));
    410   case ')': return AsmToken(AsmToken::RParen, StringRef(TokStart, 1));
    411   case '[': return AsmToken(AsmToken::LBrac, StringRef(TokStart, 1));
    412   case ']': return AsmToken(AsmToken::RBrac, StringRef(TokStart, 1));
    413   case '{': return AsmToken(AsmToken::LCurly, StringRef(TokStart, 1));
    414   case '}': return AsmToken(AsmToken::RCurly, StringRef(TokStart, 1));
    415   case '*': return AsmToken(AsmToken::Star, StringRef(TokStart, 1));
    416   case ',': return AsmToken(AsmToken::Comma, StringRef(TokStart, 1));
    417   case '$': return AsmToken(AsmToken::Dollar, StringRef(TokStart, 1));
    418   case '@': return AsmToken(AsmToken::At, StringRef(TokStart, 1));
    419   case '\\': return AsmToken(AsmToken::BackSlash, StringRef(TokStart, 1));
    420   case '=':
    421     if (*CurPtr == '=')
    422       return ++CurPtr, AsmToken(AsmToken::EqualEqual, StringRef(TokStart, 2));
    423     return AsmToken(AsmToken::Equal, StringRef(TokStart, 1));
    424   case '|':
    425     if (*CurPtr == '|')
    426       return ++CurPtr, AsmToken(AsmToken::PipePipe, StringRef(TokStart, 2));
    427     return AsmToken(AsmToken::Pipe, StringRef(TokStart, 1));
    428   case '^': return AsmToken(AsmToken::Caret, StringRef(TokStart, 1));
    429   case '&':
    430     if (*CurPtr == '&')
    431       return ++CurPtr, AsmToken(AsmToken::AmpAmp, StringRef(TokStart, 2));
    432     return AsmToken(AsmToken::Amp, StringRef(TokStart, 1));
    433   case '!':
    434     if (*CurPtr == '=')
    435       return ++CurPtr, AsmToken(AsmToken::ExclaimEqual, StringRef(TokStart, 2));
    436     return AsmToken(AsmToken::Exclaim, StringRef(TokStart, 1));
    437   case '%': return AsmToken(AsmToken::Percent, StringRef(TokStart, 1));
    438   case '/': return LexSlash();
    439   case '#': return AsmToken(AsmToken::Hash, StringRef(TokStart, 1));
    440   case '\'': return LexSingleQuote();
    441   case '"': return LexQuote();
    442   case '0': case '1': case '2': case '3': case '4':
    443   case '5': case '6': case '7': case '8': case '9':
    444     return LexDigit();
    445   case '<':
    446     switch (*CurPtr) {
    447     case '<': return ++CurPtr, AsmToken(AsmToken::LessLess,
    448                                         StringRef(TokStart, 2));
    449     case '=': return ++CurPtr, AsmToken(AsmToken::LessEqual,
    450                                         StringRef(TokStart, 2));
    451     case '>': return ++CurPtr, AsmToken(AsmToken::LessGreater,
    452                                         StringRef(TokStart, 2));
    453     default: return AsmToken(AsmToken::Less, StringRef(TokStart, 1));
    454     }
    455   case '>':
    456     switch (*CurPtr) {
    457     case '>': return ++CurPtr, AsmToken(AsmToken::GreaterGreater,
    458                                         StringRef(TokStart, 2));
    459     case '=': return ++CurPtr, AsmToken(AsmToken::GreaterEqual,
    460                                         StringRef(TokStart, 2));
    461     default: return AsmToken(AsmToken::Greater, StringRef(TokStart, 1));
    462     }
    463 
    464   // TODO: Quoted identifiers (objc methods etc)
    465   // local labels: [0-9][:]
    466   // Forward/backward labels: [0-9][fb]
    467   // Integers, fp constants, character constants.
    468   }
    469 }
    470