clang/lib/Lex/MacroArgs.cpp

   1 //===--- MacroArgs.cpp - Formal argument info for Macros ------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file implements the MacroArgs interface.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "clang/Lex/MacroArgs.h"
  14 #include "clang/Lex/LexDiagnostic.h"
  15 #include "clang/Lex/MacroInfo.h"
  16 #include "clang/Lex/Preprocessor.h"
  17 #include "llvm/ADT/SmallString.h"
  18 #include "llvm/Support/SaveAndRestore.h"
  19 #include <algorithm>
  20
  21 using namespace clang;
  22
  23 /// MacroArgs ctor function - This destroys the vector passed in.
  24 MacroArgs *MacroArgs::create(const MacroInfo *MI,
  25                              ArrayRef<Token> UnexpArgTokens,
  26                              bool VarargsElided, Preprocessor &PP) {
  27   assert(MI->isFunctionLike() &&
  28          "Can't have args for an object-like macro!");
  29   MacroArgs **ResultEnt = nullptr;
  30   unsigned ClosestMatch = ~0U;
  31
  32   // See if we have an entry with a big enough argument list to reuse on the
  33   // free list.  If so, reuse it.
  34   for (MacroArgs **Entry = &PP.MacroArgCache; *Entry;
  35        Entry = &(*Entry)->ArgCache) {
  36     if ((*Entry)->NumUnexpArgTokens >= UnexpArgTokens.size() &&
  37         (*Entry)->NumUnexpArgTokens < ClosestMatch) {
  38       ResultEnt = Entry;
  39
  40       // If we have an exact match, use it.
  41       if ((*Entry)->NumUnexpArgTokens == UnexpArgTokens.size())
  42         break;
  43       // Otherwise, use the best fit.
  44       ClosestMatch = (*Entry)->NumUnexpArgTokens;
  45     }
  46   }
  47   MacroArgs *Result;
  48   if (!ResultEnt) {
  49     // Allocate memory for a MacroArgs object with the lexer tokens at the end,
  50     // and construct the MacroArgs object.
  51     Result = new (
  52         llvm::safe_malloc(totalSizeToAlloc<Token>(UnexpArgTokens.size())))
  53         MacroArgs(UnexpArgTokens.size(), VarargsElided, MI->getNumParams());
  54   } else {
  55     Result = *ResultEnt;
  56     // Unlink this node from the preprocessors singly linked list.
  57     *ResultEnt = Result->ArgCache;
  58     Result->NumUnexpArgTokens = UnexpArgTokens.size();
  59     Result->VarargsElided = VarargsElided;
  60     Result->NumMacroArgs = MI->getNumParams();
  61   }
  62
  63   // Copy the actual unexpanded tokens to immediately after the result ptr.
  64   if (!UnexpArgTokens.empty()) {
  65     static_assert(std::is_trivial<Token>::value,
  66                   "assume trivial copyability if copying into the "
  67                   "uninitialized array (as opposed to reusing a cached "
  68                   "MacroArgs)");
  69     std::copy(UnexpArgTokens.begin(), UnexpArgTokens.end(),
  70               Result->getTrailingObjects<Token>());
  71   }
  72
  73   return Result;
  74 }
  75
  76 /// destroy - Destroy and deallocate the memory for this object.
  77 ///
  78 void MacroArgs::destroy(Preprocessor &PP) {
  79   // Don't clear PreExpArgTokens, just clear the entries.  Clearing the entries
  80   // would deallocate the element vectors.
  81   for (unsigned i = 0, e = PreExpArgTokens.size(); i != e; ++i)
  82     PreExpArgTokens[i].clear();
  83
  84   // Add this to the preprocessor's free list.
  85   ArgCache = PP.MacroArgCache;
  86   PP.MacroArgCache = this;
  87 }
  88
  89 /// deallocate - This should only be called by the Preprocessor when managing
  90 /// its freelist.
  91 MacroArgs *MacroArgs::deallocate() {
  92   MacroArgs *Next = ArgCache;
  93
  94   // Run the dtor to deallocate the vectors.
  95   this->~MacroArgs();
  96   // Release the memory for the object.
  97   static_assert(std::is_trivially_destructible<Token>::value,
  98                 "assume trivially destructible and forego destructors");
  99   free(this);
 100
 101   return Next;
 102 }
 103
 104
 105 /// getArgLength - Given a pointer to an expanded or unexpanded argument,
 106 /// return the number of tokens, not counting the EOF, that make up the
 107 /// argument.
 108 unsigned MacroArgs::getArgLength(const Token *ArgPtr) {
 109   unsigned NumArgTokens = 0;
 110   for (; ArgPtr->isNot(tok::eof); ++ArgPtr)
 111     ++NumArgTokens;
 112   return NumArgTokens;
 113 }
 114
 115
 116 /// getUnexpArgument - Return the unexpanded tokens for the specified formal.
 117 ///
 118 const Token *MacroArgs::getUnexpArgument(unsigned Arg) const {
 119
 120   assert(Arg < getNumMacroArguments() && "Invalid arg #");
 121   // The unexpanded argument tokens start immediately after the MacroArgs object
 122   // in memory.
 123   const Token *Start = getTrailingObjects<Token>();
 124   const Token *Result = Start;
 125
 126   // Scan to find Arg.
 127   for (; Arg; ++Result) {
 128     assert(Result < Start+NumUnexpArgTokens && "Invalid arg #");
 129     if (Result->is(tok::eof))
 130       --Arg;
 131   }
 132   assert(Result < Start+NumUnexpArgTokens && "Invalid arg #");
 133   return Result;
 134 }
 135
 136 bool MacroArgs::invokedWithVariadicArgument(const MacroInfo *const MI,
 137                                             Preprocessor &PP) {
 138   if (!MI->isVariadic())
 139     return false;
 140   const int VariadicArgIndex = getNumMacroArguments() - 1;
 141   return getPreExpArgument(VariadicArgIndex, PP).front().isNot(tok::eof);
 142 }
 143
 144 /// ArgNeedsPreexpansion - If we can prove that the argument won't be affected
 145 /// by pre-expansion, return false.  Otherwise, conservatively return true.
 146 bool MacroArgs::ArgNeedsPreexpansion(const Token *ArgTok,
 147                                      Preprocessor &PP) const {
 148   // If there are no identifiers in the argument list, or if the identifiers are
 149   // known to not be macros, pre-expansion won't modify it.
 150   for (; ArgTok->isNot(tok::eof); ++ArgTok)
 151     if (IdentifierInfo *II = ArgTok->getIdentifierInfo())
 152       if (II->hasMacroDefinition())
 153         // Return true even though the macro could be a function-like macro
 154         // without a following '(' token, or could be disabled, or not visible.
 155         return true;
 156   return false;
 157 }
 158
 159 /// getPreExpArgument - Return the pre-expanded form of the specified
 160 /// argument.
 161 const std::vector<Token> &MacroArgs::getPreExpArgument(unsigned Arg,
 162                                                        Preprocessor &PP) {
 163   assert(Arg < getNumMacroArguments() && "Invalid argument number!");
 164
 165   // If we have already computed this, return it.
 166   if (PreExpArgTokens.size() < getNumMacroArguments())
 167     PreExpArgTokens.resize(getNumMacroArguments());
 168
 169   std::vector<Token> &Result = PreExpArgTokens[Arg];
 170   if (!Result.empty()) return Result;
 171
 172   SaveAndRestore<bool> PreExpandingMacroArgs(PP.InMacroArgPreExpansion, true);
 173
 174   const Token *AT = getUnexpArgument(Arg);
 175   unsigned NumToks = getArgLength(AT)+1;  // Include the EOF.
 176
 177   // Otherwise, we have to pre-expand this argument, populating Result.  To do
 178   // this, we set up a fake TokenLexer to lex from the unexpanded argument
 179   // list.  With this installed, we lex expanded tokens until we hit the EOF
 180   // token at the end of the unexp list.
 181   PP.EnterTokenStream(AT, NumToks, false /*disable expand*/,
 182                       false /*owns tokens*/, false /*is reinject*/);
 183
 184   // Lex all of the macro-expanded tokens into Result.
 185   do {
 186     Result.push_back(Token());
 187     Token &Tok = Result.back();
 188     PP.Lex(Tok);
 189   } while (Result.back().isNot(tok::eof));
 190
 191   // Pop the token stream off the top of the stack.  We know that the internal
 192   // pointer inside of it is to the "end" of the token stream, but the stack
 193   // will not otherwise be popped until the next token is lexed.  The problem is
 194   // that the token may be lexed sometime after the vector of tokens itself is
 195   // destroyed, which would be badness.
 196   if (PP.InCachingLexMode())
 197     PP.ExitCachingLexMode();
 198   PP.RemoveTopOfLexerStack();
 199   return Result;
 200 }
 201
 202
 203 /// StringifyArgument - Implement C99 6.10.3.2p2, converting a sequence of
 204 /// tokens into the literal string token that should be produced by the C #
 205 /// preprocessor operator.  If Charify is true, then it should be turned into
 206 /// a character literal for the Microsoft charize (#@) extension.
 207 ///
 208 Token MacroArgs::StringifyArgument(const Token *ArgToks,
 209                                    Preprocessor &PP, bool Charify,
 210                                    SourceLocation ExpansionLocStart,
 211                                    SourceLocation ExpansionLocEnd) {
 212   Token Tok;
 213   Tok.startToken();
 214   Tok.setKind(Charify ? tok::char_constant : tok::string_literal);
 215
 216   const Token *ArgTokStart = ArgToks;
 217
 218   // Stringify all the tokens.
 219   SmallString<128> Result;
 220   Result += "\"";
 221
 222   bool isFirst = true;
 223   for (; ArgToks->isNot(tok::eof); ++ArgToks) {
 224     const Token &Tok = *ArgToks;
 225     if (!isFirst && (Tok.hasLeadingSpace() || Tok.isAtStartOfLine()))
 226       Result += ' ';
 227     isFirst = false;
 228
 229     // If this is a string or character constant, escape the token as specified
 230     // by 6.10.3.2p2.
 231     if (tok::isStringLiteral(Tok.getKind()) || // "foo", u8R"x(foo)x"_bar, etc.
 232         Tok.is(tok::char_constant) ||          // 'x'
 233         Tok.is(tok::wide_char_constant) ||     // L'x'.
 234         Tok.is(tok::utf8_char_constant) ||     // u8'x'.
 235         Tok.is(tok::utf16_char_constant) ||    // u'x'.
 236         Tok.is(tok::utf32_char_constant)) {    // U'x'.
 237       bool Invalid = false;
 238       std::string TokStr = PP.getSpelling(Tok, &Invalid);
 239       if (!Invalid) {
 240         std::string Str = Lexer::Stringify(TokStr);
 241         Result.append(Str.begin(), Str.end());
 242       }
 243     } else if (Tok.is(tok::code_completion)) {
 244       PP.CodeCompleteNaturalLanguage();
 245     } else {
 246       // Otherwise, just append the token.  Do some gymnastics to get the token
 247       // in place and avoid copies where possible.
 248       unsigned CurStrLen = Result.size();
 249       Result.resize(CurStrLen+Tok.getLength());
 250       const char *BufPtr = Result.data() + CurStrLen;
 251       bool Invalid = false;
 252       unsigned ActualTokLen = PP.getSpelling(Tok, BufPtr, &Invalid);
 253
 254       if (!Invalid) {
 255         // If getSpelling returned a pointer to an already uniqued version of
 256         // the string instead of filling in BufPtr, memcpy it onto our string.
 257         if (ActualTokLen && BufPtr != &Result[CurStrLen])
 258           memcpy(&Result[CurStrLen], BufPtr, ActualTokLen);
 259
 260         // If the token was dirty, the spelling may be shorter than the token.
 261         if (ActualTokLen != Tok.getLength())
 262           Result.resize(CurStrLen+ActualTokLen);
 263       }
 264     }
 265   }
 266
 267   // If the last character of the string is a \, and if it isn't escaped, this
 268   // is an invalid string literal, diagnose it as specified in C99.
 269   if (Result.back() == '\\') {
 270     // Count the number of consecutive \ characters.  If even, then they are
 271     // just escaped backslashes, otherwise it's an error.
 272     unsigned FirstNonSlash = Result.size()-2;
 273     // Guaranteed to find the starting " if nothing else.
 274     while (Result[FirstNonSlash] == '\\')
 275       --FirstNonSlash;
 276     if ((Result.size()-1-FirstNonSlash) & 1) {
 277       // Diagnose errors for things like: #define F(X) #X   /   F(\)
 278       PP.Diag(ArgToks[-1], diag::pp_invalid_string_literal);
 279       Result.pop_back();  // remove one of the \'s.
 280     }
 281   }
 282   Result += '"';
 283
 284   // If this is the charify operation and the result is not a legal character
 285   // constant, diagnose it.
 286   if (Charify) {
 287     // First step, turn double quotes into single quotes:
 288     Result[0] = '\'';
 289     Result[Result.size()-1] = '\'';
 290
 291     // Check for bogus character.
 292     bool isBad = false;
 293     if (Result.size() == 3)
 294       isBad = Result[1] == '\'';   // ''' is not legal. '\' already fixed above.
 295     else
 296       isBad = (Result.size() != 4 || Result[1] != '\\');  // Not '\x'
 297
 298     if (isBad) {
 299       PP.Diag(ArgTokStart[0], diag::err_invalid_character_to_charify);
 300       Result = "' '";  // Use something arbitrary, but legal.
 301     }
 302   }
 303
 304   PP.CreateString(Result, Tok,
 305                   ExpansionLocStart, ExpansionLocEnd);
 306   return Tok;
 307 }