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 } 308