1 //===--- PPExpressions.cpp - Preprocessor Expression Evaluation -----------===// 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 Preprocessor::EvaluateDirectiveExpression method, 10 // which parses and evaluates integer constant expressions for #if directives. 11 // 12 //===----------------------------------------------------------------------===// 13 // 14 // FIXME: implement testing for #assert's. 15 // 16 //===----------------------------------------------------------------------===// 17 18 #include "clang/Basic/IdentifierTable.h" 19 #include "clang/Basic/SourceLocation.h" 20 #include "clang/Basic/SourceManager.h" 21 #include "clang/Basic/TargetInfo.h" 22 #include "clang/Basic/TokenKinds.h" 23 #include "clang/Lex/CodeCompletionHandler.h" 24 #include "clang/Lex/LexDiagnostic.h" 25 #include "clang/Lex/LiteralSupport.h" 26 #include "clang/Lex/MacroInfo.h" 27 #include "clang/Lex/PPCallbacks.h" 28 #include "clang/Lex/Preprocessor.h" 29 #include "clang/Lex/Token.h" 30 #include "llvm/ADT/APSInt.h" 31 #include "llvm/ADT/STLExtras.h" 32 #include "llvm/ADT/StringExtras.h" 33 #include "llvm/ADT/StringRef.h" 34 #include "llvm/Support/ErrorHandling.h" 35 #include "llvm/Support/SaveAndRestore.h" 36 #include <cassert> 37 38 using namespace clang; 39 40 namespace { 41 42 /// PPValue - Represents the value of a subexpression of a preprocessor 43 /// conditional and the source range covered by it. 44 class PPValue { 45 SourceRange Range; 46 IdentifierInfo *II = nullptr; 47 48 public: 49 llvm::APSInt Val; 50 51 // Default ctor - Construct an 'invalid' PPValue. 52 PPValue(unsigned BitWidth) : Val(BitWidth) {} 53 54 // If this value was produced by directly evaluating an identifier, produce 55 // that identifier. 56 IdentifierInfo *getIdentifier() const { return II; } 57 void setIdentifier(IdentifierInfo *II) { this->II = II; } 58 59 unsigned getBitWidth() const { return Val.getBitWidth(); } 60 bool isUnsigned() const { return Val.isUnsigned(); } 61 62 SourceRange getRange() const { return Range; } 63 64 void setRange(SourceLocation L) { Range.setBegin(L); Range.setEnd(L); } 65 void setRange(SourceLocation B, SourceLocation E) { 66 Range.setBegin(B); Range.setEnd(E); 67 } 68 void setBegin(SourceLocation L) { Range.setBegin(L); } 69 void setEnd(SourceLocation L) { Range.setEnd(L); } 70 }; 71 72 } // end anonymous namespace 73 74 static bool EvaluateDirectiveSubExpr(PPValue &LHS, unsigned MinPrec, 75 Token &PeekTok, bool ValueLive, 76 bool &IncludedUndefinedIds, 77 Preprocessor &PP); 78 79 /// DefinedTracker - This struct is used while parsing expressions to keep track 80 /// of whether !defined(X) has been seen. 81 /// 82 /// With this simple scheme, we handle the basic forms: 83 /// !defined(X) and !defined X 84 /// but we also trivially handle (silly) stuff like: 85 /// !!!defined(X) and +!defined(X) and !+!+!defined(X) and !(defined(X)). 86 struct DefinedTracker { 87 /// Each time a Value is evaluated, it returns information about whether the 88 /// parsed value is of the form defined(X), !defined(X) or is something else. 89 enum TrackerState { 90 DefinedMacro, // defined(X) 91 NotDefinedMacro, // !defined(X) 92 Unknown // Something else. 93 } State; 94 /// TheMacro - When the state is DefinedMacro or NotDefinedMacro, this 95 /// indicates the macro that was checked. 96 IdentifierInfo *TheMacro; 97 bool IncludedUndefinedIds = false; 98 }; 99 100 /// EvaluateDefined - Process a 'defined(sym)' expression. 101 static bool EvaluateDefined(PPValue &Result, Token &PeekTok, DefinedTracker &DT, 102 bool ValueLive, Preprocessor &PP) { 103 SourceLocation beginLoc(PeekTok.getLocation()); 104 Result.setBegin(beginLoc); 105 106 // Get the next token, don't expand it. 107 PP.LexUnexpandedNonComment(PeekTok); 108 109 // Two options, it can either be a pp-identifier or a (. 110 SourceLocation LParenLoc; 111 if (PeekTok.is(tok::l_paren)) { 112 // Found a paren, remember we saw it and skip it. 113 LParenLoc = PeekTok.getLocation(); 114 PP.LexUnexpandedNonComment(PeekTok); 115 } 116 117 if (PeekTok.is(tok::code_completion)) { 118 if (PP.getCodeCompletionHandler()) 119 PP.getCodeCompletionHandler()->CodeCompleteMacroName(false); 120 PP.setCodeCompletionReached(); 121 PP.LexUnexpandedNonComment(PeekTok); 122 } 123 124 // If we don't have a pp-identifier now, this is an error. 125 if (PP.CheckMacroName(PeekTok, MU_Other)) 126 return true; 127 128 // Otherwise, we got an identifier, is it defined to something? 129 IdentifierInfo *II = PeekTok.getIdentifierInfo(); 130 MacroDefinition Macro = PP.getMacroDefinition(II); 131 Result.Val = !!Macro; 132 Result.Val.setIsUnsigned(false); // Result is signed intmax_t. 133 DT.IncludedUndefinedIds = !Macro; 134 135 PP.emitMacroExpansionWarnings( 136 PeekTok, 137 (II->getName() == "INFINITY" || II->getName() == "NAN") ? true : false); 138 139 // If there is a macro, mark it used. 140 if (Result.Val != 0 && ValueLive) 141 PP.markMacroAsUsed(Macro.getMacroInfo()); 142 143 // Save macro token for callback. 144 Token macroToken(PeekTok); 145 146 // If we are in parens, ensure we have a trailing ). 147 if (LParenLoc.isValid()) { 148 // Consume identifier. 149 Result.setEnd(PeekTok.getLocation()); 150 PP.LexUnexpandedNonComment(PeekTok); 151 152 if (PeekTok.isNot(tok::r_paren)) { 153 PP.Diag(PeekTok.getLocation(), diag::err_pp_expected_after) 154 << "'defined'" << tok::r_paren; 155 PP.Diag(LParenLoc, diag::note_matching) << tok::l_paren; 156 return true; 157 } 158 // Consume the ). 159 PP.LexNonComment(PeekTok); 160 Result.setEnd(PeekTok.getLocation()); 161 } else { 162 // Consume identifier. 163 Result.setEnd(PeekTok.getLocation()); 164 PP.LexNonComment(PeekTok); 165 } 166 167 // [cpp.cond]p4: 168 // Prior to evaluation, macro invocations in the list of preprocessing 169 // tokens that will become the controlling constant expression are replaced 170 // (except for those macro names modified by the 'defined' unary operator), 171 // just as in normal text. If the token 'defined' is generated as a result 172 // of this replacement process or use of the 'defined' unary operator does 173 // not match one of the two specified forms prior to macro replacement, the 174 // behavior is undefined. 175 // This isn't an idle threat, consider this program: 176 // #define FOO 177 // #define BAR defined(FOO) 178 // #if BAR 179 // ... 180 // #else 181 // ... 182 // #endif 183 // clang and gcc will pick the #if branch while Visual Studio will take the 184 // #else branch. Emit a warning about this undefined behavior. 185 if (beginLoc.isMacroID()) { 186 bool IsFunctionTypeMacro = 187 PP.getSourceManager() 188 .getSLocEntry(PP.getSourceManager().getFileID(beginLoc)) 189 .getExpansion() 190 .isFunctionMacroExpansion(); 191 // For object-type macros, it's easy to replace 192 // #define FOO defined(BAR) 193 // with 194 // #if defined(BAR) 195 // #define FOO 1 196 // #else 197 // #define FOO 0 198 // #endif 199 // and doing so makes sense since compilers handle this differently in 200 // practice (see example further up). But for function-type macros, 201 // there is no good way to write 202 // # define FOO(x) (defined(M_ ## x) && M_ ## x) 203 // in a different way, and compilers seem to agree on how to behave here. 204 // So warn by default on object-type macros, but only warn in -pedantic 205 // mode on function-type macros. 206 if (IsFunctionTypeMacro) 207 PP.Diag(beginLoc, diag::warn_defined_in_function_type_macro); 208 else 209 PP.Diag(beginLoc, diag::warn_defined_in_object_type_macro); 210 } 211 212 // Invoke the 'defined' callback. 213 if (PPCallbacks *Callbacks = PP.getPPCallbacks()) { 214 Callbacks->Defined(macroToken, Macro, 215 SourceRange(beginLoc, PeekTok.getLocation())); 216 } 217 218 // Success, remember that we saw defined(X). 219 DT.State = DefinedTracker::DefinedMacro; 220 DT.TheMacro = II; 221 return false; 222 } 223 224 /// EvaluateValue - Evaluate the token PeekTok (and any others needed) and 225 /// return the computed value in Result. Return true if there was an error 226 /// parsing. This function also returns information about the form of the 227 /// expression in DT. See above for information on what DT means. 228 /// 229 /// If ValueLive is false, then this value is being evaluated in a context where 230 /// the result is not used. As such, avoid diagnostics that relate to 231 /// evaluation. 232 static bool EvaluateValue(PPValue &Result, Token &PeekTok, DefinedTracker &DT, 233 bool ValueLive, Preprocessor &PP) { 234 DT.State = DefinedTracker::Unknown; 235 236 Result.setIdentifier(nullptr); 237 238 if (PeekTok.is(tok::code_completion)) { 239 if (PP.getCodeCompletionHandler()) 240 PP.getCodeCompletionHandler()->CodeCompletePreprocessorExpression(); 241 PP.setCodeCompletionReached(); 242 PP.LexNonComment(PeekTok); 243 } 244 245 switch (PeekTok.getKind()) { 246 default: 247 // If this token's spelling is a pp-identifier, check to see if it is 248 // 'defined' or if it is a macro. Note that we check here because many 249 // keywords are pp-identifiers, so we can't check the kind. 250 if (IdentifierInfo *II = PeekTok.getIdentifierInfo()) { 251 // Handle "defined X" and "defined(X)". 252 if (II->isStr("defined")) 253 return EvaluateDefined(Result, PeekTok, DT, ValueLive, PP); 254 255 if (!II->isCPlusPlusOperatorKeyword()) { 256 // If this identifier isn't 'defined' or one of the special 257 // preprocessor keywords and it wasn't macro expanded, it turns 258 // into a simple 0 259 if (ValueLive) { 260 PP.Diag(PeekTok, diag::warn_pp_undef_identifier) << II; 261 262 const DiagnosticsEngine &DiagEngine = PP.getDiagnostics(); 263 // If 'Wundef' is enabled, do not emit 'undef-prefix' diagnostics. 264 if (DiagEngine.isIgnored(diag::warn_pp_undef_identifier, 265 PeekTok.getLocation())) { 266 const std::vector<std::string> UndefPrefixes = 267 DiagEngine.getDiagnosticOptions().UndefPrefixes; 268 const StringRef IdentifierName = II->getName(); 269 if (llvm::any_of(UndefPrefixes, 270 [&IdentifierName](const std::string &Prefix) { 271 return IdentifierName.starts_with(Prefix); 272 })) 273 PP.Diag(PeekTok, diag::warn_pp_undef_prefix) 274 << AddFlagValue{llvm::join(UndefPrefixes, ",")} << II; 275 } 276 } 277 Result.Val = 0; 278 Result.Val.setIsUnsigned(false); // "0" is signed intmax_t 0. 279 Result.setIdentifier(II); 280 Result.setRange(PeekTok.getLocation()); 281 DT.IncludedUndefinedIds = true; 282 PP.LexNonComment(PeekTok); 283 return false; 284 } 285 } 286 PP.Diag(PeekTok, diag::err_pp_expr_bad_token_start_expr); 287 return true; 288 case tok::eod: 289 case tok::r_paren: 290 // If there is no expression, report and exit. 291 PP.Diag(PeekTok, diag::err_pp_expected_value_in_expr); 292 return true; 293 case tok::numeric_constant: { 294 SmallString<64> IntegerBuffer; 295 bool NumberInvalid = false; 296 StringRef Spelling = PP.getSpelling(PeekTok, IntegerBuffer, 297 &NumberInvalid); 298 if (NumberInvalid) 299 return true; // a diagnostic was already reported 300 301 NumericLiteralParser Literal(Spelling, PeekTok.getLocation(), 302 PP.getSourceManager(), PP.getLangOpts(), 303 PP.getTargetInfo(), PP.getDiagnostics()); 304 if (Literal.hadError) 305 return true; // a diagnostic was already reported. 306 307 if (Literal.isFloatingLiteral() || Literal.isImaginary) { 308 PP.Diag(PeekTok, diag::err_pp_illegal_floating_literal); 309 return true; 310 } 311 assert(Literal.isIntegerLiteral() && "Unknown ppnumber"); 312 313 // Complain about, and drop, any ud-suffix. 314 if (Literal.hasUDSuffix()) 315 PP.Diag(PeekTok, diag::err_pp_invalid_udl) << /*integer*/1; 316 317 // 'long long' is a C99 or C++11 feature. 318 if (!PP.getLangOpts().C99 && Literal.isLongLong) { 319 if (PP.getLangOpts().CPlusPlus) 320 PP.Diag(PeekTok, 321 PP.getLangOpts().CPlusPlus11 ? 322 diag::warn_cxx98_compat_longlong : diag::ext_cxx11_longlong); 323 else 324 PP.Diag(PeekTok, diag::ext_c99_longlong); 325 } 326 327 // 'z/uz' literals are a C++23 feature. 328 if (Literal.isSizeT) 329 PP.Diag(PeekTok, PP.getLangOpts().CPlusPlus 330 ? PP.getLangOpts().CPlusPlus23 331 ? diag::warn_cxx20_compat_size_t_suffix 332 : diag::ext_cxx23_size_t_suffix 333 : diag::err_cxx23_size_t_suffix); 334 335 // 'wb/uwb' literals are a C23 feature. 336 // '__wb/__uwb' are a C++ extension. 337 if (Literal.isBitInt) 338 PP.Diag(PeekTok, PP.getLangOpts().CPlusPlus ? diag::ext_cxx_bitint_suffix 339 : PP.getLangOpts().C23 340 ? diag::warn_c23_compat_bitint_suffix 341 : diag::ext_c23_bitint_suffix); 342 343 // Parse the integer literal into Result. 344 if (Literal.GetIntegerValue(Result.Val)) { 345 // Overflow parsing integer literal. 346 if (ValueLive) 347 PP.Diag(PeekTok, diag::err_integer_literal_too_large) 348 << /* Unsigned */ 1; 349 Result.Val.setIsUnsigned(true); 350 } else { 351 // Set the signedness of the result to match whether there was a U suffix 352 // or not. 353 Result.Val.setIsUnsigned(Literal.isUnsigned); 354 355 // Detect overflow based on whether the value is signed. If signed 356 // and if the value is too large, emit a warning "integer constant is so 357 // large that it is unsigned" e.g. on 12345678901234567890 where intmax_t 358 // is 64-bits. 359 if (!Literal.isUnsigned && Result.Val.isNegative()) { 360 // Octal, hexadecimal, and binary literals are implicitly unsigned if 361 // the value does not fit into a signed integer type. 362 if (ValueLive && Literal.getRadix() == 10) 363 PP.Diag(PeekTok, diag::ext_integer_literal_too_large_for_signed); 364 Result.Val.setIsUnsigned(true); 365 } 366 } 367 368 // Consume the token. 369 Result.setRange(PeekTok.getLocation()); 370 PP.LexNonComment(PeekTok); 371 return false; 372 } 373 case tok::char_constant: // 'x' 374 case tok::wide_char_constant: // L'x' 375 case tok::utf8_char_constant: // u8'x' 376 case tok::utf16_char_constant: // u'x' 377 case tok::utf32_char_constant: { // U'x' 378 // Complain about, and drop, any ud-suffix. 379 if (PeekTok.hasUDSuffix()) 380 PP.Diag(PeekTok, diag::err_pp_invalid_udl) << /*character*/0; 381 382 SmallString<32> CharBuffer; 383 bool CharInvalid = false; 384 StringRef ThisTok = PP.getSpelling(PeekTok, CharBuffer, &CharInvalid); 385 if (CharInvalid) 386 return true; 387 388 CharLiteralParser Literal(ThisTok.begin(), ThisTok.end(), 389 PeekTok.getLocation(), PP, PeekTok.getKind()); 390 if (Literal.hadError()) 391 return true; // A diagnostic was already emitted. 392 393 // Character literals are always int or wchar_t, expand to intmax_t. 394 const TargetInfo &TI = PP.getTargetInfo(); 395 unsigned NumBits; 396 if (Literal.isMultiChar()) 397 NumBits = TI.getIntWidth(); 398 else if (Literal.isWide()) 399 NumBits = TI.getWCharWidth(); 400 else if (Literal.isUTF16()) 401 NumBits = TI.getChar16Width(); 402 else if (Literal.isUTF32()) 403 NumBits = TI.getChar32Width(); 404 else // char or char8_t 405 NumBits = TI.getCharWidth(); 406 407 // Set the width. 408 llvm::APSInt Val(NumBits); 409 // Set the value. 410 Val = Literal.getValue(); 411 // Set the signedness. UTF-16 and UTF-32 are always unsigned 412 // UTF-8 is unsigned if -fchar8_t is specified. 413 if (Literal.isWide()) 414 Val.setIsUnsigned(!TargetInfo::isTypeSigned(TI.getWCharType())); 415 else if (Literal.isUTF16() || Literal.isUTF32()) 416 Val.setIsUnsigned(true); 417 else if (Literal.isUTF8()) { 418 if (PP.getLangOpts().CPlusPlus) 419 Val.setIsUnsigned( 420 PP.getLangOpts().Char8 ? true : !PP.getLangOpts().CharIsSigned); 421 else 422 Val.setIsUnsigned(true); 423 } else 424 Val.setIsUnsigned(!PP.getLangOpts().CharIsSigned); 425 426 if (Result.Val.getBitWidth() > Val.getBitWidth()) { 427 Result.Val = Val.extend(Result.Val.getBitWidth()); 428 } else { 429 assert(Result.Val.getBitWidth() == Val.getBitWidth() && 430 "intmax_t smaller than char/wchar_t?"); 431 Result.Val = Val; 432 } 433 434 // Consume the token. 435 Result.setRange(PeekTok.getLocation()); 436 PP.LexNonComment(PeekTok); 437 return false; 438 } 439 case tok::l_paren: { 440 SourceLocation Start = PeekTok.getLocation(); 441 PP.LexNonComment(PeekTok); // Eat the (. 442 // Parse the value and if there are any binary operators involved, parse 443 // them. 444 if (EvaluateValue(Result, PeekTok, DT, ValueLive, PP)) return true; 445 446 // If this is a silly value like (X), which doesn't need parens, check for 447 // !(defined X). 448 if (PeekTok.is(tok::r_paren)) { 449 // Just use DT unmodified as our result. 450 } else { 451 // Otherwise, we have something like (x+y), and we consumed '(x'. 452 if (EvaluateDirectiveSubExpr(Result, 1, PeekTok, ValueLive, 453 DT.IncludedUndefinedIds, PP)) 454 return true; 455 456 if (PeekTok.isNot(tok::r_paren)) { 457 PP.Diag(PeekTok.getLocation(), diag::err_pp_expected_rparen) 458 << Result.getRange(); 459 PP.Diag(Start, diag::note_matching) << tok::l_paren; 460 return true; 461 } 462 DT.State = DefinedTracker::Unknown; 463 } 464 Result.setRange(Start, PeekTok.getLocation()); 465 Result.setIdentifier(nullptr); 466 PP.LexNonComment(PeekTok); // Eat the ). 467 return false; 468 } 469 case tok::plus: { 470 SourceLocation Start = PeekTok.getLocation(); 471 // Unary plus doesn't modify the value. 472 PP.LexNonComment(PeekTok); 473 if (EvaluateValue(Result, PeekTok, DT, ValueLive, PP)) return true; 474 Result.setBegin(Start); 475 Result.setIdentifier(nullptr); 476 return false; 477 } 478 case tok::minus: { 479 SourceLocation Loc = PeekTok.getLocation(); 480 PP.LexNonComment(PeekTok); 481 if (EvaluateValue(Result, PeekTok, DT, ValueLive, PP)) return true; 482 Result.setBegin(Loc); 483 Result.setIdentifier(nullptr); 484 485 // C99 6.5.3.3p3: The sign of the result matches the sign of the operand. 486 Result.Val = -Result.Val; 487 488 // -MININT is the only thing that overflows. Unsigned never overflows. 489 bool Overflow = !Result.isUnsigned() && Result.Val.isMinSignedValue(); 490 491 // If this operator is live and overflowed, report the issue. 492 if (Overflow && ValueLive) 493 PP.Diag(Loc, diag::warn_pp_expr_overflow) << Result.getRange(); 494 495 DT.State = DefinedTracker::Unknown; 496 return false; 497 } 498 499 case tok::tilde: { 500 SourceLocation Start = PeekTok.getLocation(); 501 PP.LexNonComment(PeekTok); 502 if (EvaluateValue(Result, PeekTok, DT, ValueLive, PP)) return true; 503 Result.setBegin(Start); 504 Result.setIdentifier(nullptr); 505 506 // C99 6.5.3.3p4: The sign of the result matches the sign of the operand. 507 Result.Val = ~Result.Val; 508 DT.State = DefinedTracker::Unknown; 509 return false; 510 } 511 512 case tok::exclaim: { 513 SourceLocation Start = PeekTok.getLocation(); 514 PP.LexNonComment(PeekTok); 515 if (EvaluateValue(Result, PeekTok, DT, ValueLive, PP)) return true; 516 Result.setBegin(Start); 517 Result.Val = !Result.Val; 518 // C99 6.5.3.3p5: The sign of the result is 'int', aka it is signed. 519 Result.Val.setIsUnsigned(false); 520 Result.setIdentifier(nullptr); 521 522 if (DT.State == DefinedTracker::DefinedMacro) 523 DT.State = DefinedTracker::NotDefinedMacro; 524 else if (DT.State == DefinedTracker::NotDefinedMacro) 525 DT.State = DefinedTracker::DefinedMacro; 526 return false; 527 } 528 case tok::kw_true: 529 case tok::kw_false: 530 Result.Val = PeekTok.getKind() == tok::kw_true; 531 Result.Val.setIsUnsigned(false); // "0" is signed intmax_t 0. 532 Result.setIdentifier(PeekTok.getIdentifierInfo()); 533 Result.setRange(PeekTok.getLocation()); 534 PP.LexNonComment(PeekTok); 535 return false; 536 537 // FIXME: Handle #assert 538 } 539 } 540 541 /// getPrecedence - Return the precedence of the specified binary operator 542 /// token. This returns: 543 /// ~0 - Invalid token. 544 /// 14 -> 3 - various operators. 545 /// 0 - 'eod' or ')' 546 static unsigned getPrecedence(tok::TokenKind Kind) { 547 switch (Kind) { 548 default: return ~0U; 549 case tok::percent: 550 case tok::slash: 551 case tok::star: return 14; 552 case tok::plus: 553 case tok::minus: return 13; 554 case tok::lessless: 555 case tok::greatergreater: return 12; 556 case tok::lessequal: 557 case tok::less: 558 case tok::greaterequal: 559 case tok::greater: return 11; 560 case tok::exclaimequal: 561 case tok::equalequal: return 10; 562 case tok::amp: return 9; 563 case tok::caret: return 8; 564 case tok::pipe: return 7; 565 case tok::ampamp: return 6; 566 case tok::pipepipe: return 5; 567 case tok::question: return 4; 568 case tok::comma: return 3; 569 case tok::colon: return 2; 570 case tok::r_paren: return 0;// Lowest priority, end of expr. 571 case tok::eod: return 0;// Lowest priority, end of directive. 572 } 573 } 574 575 static void diagnoseUnexpectedOperator(Preprocessor &PP, PPValue &LHS, 576 Token &Tok) { 577 if (Tok.is(tok::l_paren) && LHS.getIdentifier()) 578 PP.Diag(LHS.getRange().getBegin(), diag::err_pp_expr_bad_token_lparen) 579 << LHS.getIdentifier(); 580 else 581 PP.Diag(Tok.getLocation(), diag::err_pp_expr_bad_token_binop) 582 << LHS.getRange(); 583 } 584 585 /// EvaluateDirectiveSubExpr - Evaluate the subexpression whose first token is 586 /// PeekTok, and whose precedence is PeekPrec. This returns the result in LHS. 587 /// 588 /// If ValueLive is false, then this value is being evaluated in a context where 589 /// the result is not used. As such, avoid diagnostics that relate to 590 /// evaluation, such as division by zero warnings. 591 static bool EvaluateDirectiveSubExpr(PPValue &LHS, unsigned MinPrec, 592 Token &PeekTok, bool ValueLive, 593 bool &IncludedUndefinedIds, 594 Preprocessor &PP) { 595 unsigned PeekPrec = getPrecedence(PeekTok.getKind()); 596 // If this token isn't valid, report the error. 597 if (PeekPrec == ~0U) { 598 diagnoseUnexpectedOperator(PP, LHS, PeekTok); 599 return true; 600 } 601 602 while (true) { 603 // If this token has a lower precedence than we are allowed to parse, return 604 // it so that higher levels of the recursion can parse it. 605 if (PeekPrec < MinPrec) 606 return false; 607 608 tok::TokenKind Operator = PeekTok.getKind(); 609 610 // If this is a short-circuiting operator, see if the RHS of the operator is 611 // dead. Note that this cannot just clobber ValueLive. Consider 612 // "0 && 1 ? 4 : 1 / 0", which is parsed as "(0 && 1) ? 4 : (1 / 0)". In 613 // this example, the RHS of the && being dead does not make the rest of the 614 // expr dead. 615 bool RHSIsLive; 616 if (Operator == tok::ampamp && LHS.Val == 0) 617 RHSIsLive = false; // RHS of "0 && x" is dead. 618 else if (Operator == tok::pipepipe && LHS.Val != 0) 619 RHSIsLive = false; // RHS of "1 || x" is dead. 620 else if (Operator == tok::question && LHS.Val == 0) 621 RHSIsLive = false; // RHS (x) of "0 ? x : y" is dead. 622 else 623 RHSIsLive = ValueLive; 624 625 // Consume the operator, remembering the operator's location for reporting. 626 SourceLocation OpLoc = PeekTok.getLocation(); 627 PP.LexNonComment(PeekTok); 628 629 PPValue RHS(LHS.getBitWidth()); 630 // Parse the RHS of the operator. 631 DefinedTracker DT; 632 if (EvaluateValue(RHS, PeekTok, DT, RHSIsLive, PP)) return true; 633 IncludedUndefinedIds = DT.IncludedUndefinedIds; 634 635 // Remember the precedence of this operator and get the precedence of the 636 // operator immediately to the right of the RHS. 637 unsigned ThisPrec = PeekPrec; 638 PeekPrec = getPrecedence(PeekTok.getKind()); 639 640 // If this token isn't valid, report the error. 641 if (PeekPrec == ~0U) { 642 diagnoseUnexpectedOperator(PP, RHS, PeekTok); 643 return true; 644 } 645 646 // Decide whether to include the next binop in this subexpression. For 647 // example, when parsing x+y*z and looking at '*', we want to recursively 648 // handle y*z as a single subexpression. We do this because the precedence 649 // of * is higher than that of +. The only strange case we have to handle 650 // here is for the ?: operator, where the precedence is actually lower than 651 // the LHS of the '?'. The grammar rule is: 652 // 653 // conditional-expression ::= 654 // logical-OR-expression ? expression : conditional-expression 655 // where 'expression' is actually comma-expression. 656 unsigned RHSPrec; 657 if (Operator == tok::question) 658 // The RHS of "?" should be maximally consumed as an expression. 659 RHSPrec = getPrecedence(tok::comma); 660 else // All others should munch while higher precedence. 661 RHSPrec = ThisPrec+1; 662 663 if (PeekPrec >= RHSPrec) { 664 if (EvaluateDirectiveSubExpr(RHS, RHSPrec, PeekTok, RHSIsLive, 665 IncludedUndefinedIds, PP)) 666 return true; 667 PeekPrec = getPrecedence(PeekTok.getKind()); 668 } 669 assert(PeekPrec <= ThisPrec && "Recursion didn't work!"); 670 671 // Usual arithmetic conversions (C99 6.3.1.8p1): result is unsigned if 672 // either operand is unsigned. 673 llvm::APSInt Res(LHS.getBitWidth()); 674 switch (Operator) { 675 case tok::question: // No UAC for x and y in "x ? y : z". 676 case tok::lessless: // Shift amount doesn't UAC with shift value. 677 case tok::greatergreater: // Shift amount doesn't UAC with shift value. 678 case tok::comma: // Comma operands are not subject to UACs. 679 case tok::pipepipe: // Logical || does not do UACs. 680 case tok::ampamp: // Logical && does not do UACs. 681 break; // No UAC 682 default: 683 Res.setIsUnsigned(LHS.isUnsigned() || RHS.isUnsigned()); 684 // If this just promoted something from signed to unsigned, and if the 685 // value was negative, warn about it. 686 if (ValueLive && Res.isUnsigned()) { 687 if (!LHS.isUnsigned() && LHS.Val.isNegative()) 688 PP.Diag(OpLoc, diag::warn_pp_convert_to_positive) << 0 689 << toString(LHS.Val, 10, true) + " to " + 690 toString(LHS.Val, 10, false) 691 << LHS.getRange() << RHS.getRange(); 692 if (!RHS.isUnsigned() && RHS.Val.isNegative()) 693 PP.Diag(OpLoc, diag::warn_pp_convert_to_positive) << 1 694 << toString(RHS.Val, 10, true) + " to " + 695 toString(RHS.Val, 10, false) 696 << LHS.getRange() << RHS.getRange(); 697 } 698 LHS.Val.setIsUnsigned(Res.isUnsigned()); 699 RHS.Val.setIsUnsigned(Res.isUnsigned()); 700 } 701 702 bool Overflow = false; 703 switch (Operator) { 704 default: llvm_unreachable("Unknown operator token!"); 705 case tok::percent: 706 if (RHS.Val != 0) 707 Res = LHS.Val % RHS.Val; 708 else if (ValueLive) { 709 PP.Diag(OpLoc, diag::err_pp_remainder_by_zero) 710 << LHS.getRange() << RHS.getRange(); 711 return true; 712 } 713 break; 714 case tok::slash: 715 if (RHS.Val != 0) { 716 if (LHS.Val.isSigned()) 717 Res = llvm::APSInt(LHS.Val.sdiv_ov(RHS.Val, Overflow), false); 718 else 719 Res = LHS.Val / RHS.Val; 720 } else if (ValueLive) { 721 PP.Diag(OpLoc, diag::err_pp_division_by_zero) 722 << LHS.getRange() << RHS.getRange(); 723 return true; 724 } 725 break; 726 727 case tok::star: 728 if (Res.isSigned()) 729 Res = llvm::APSInt(LHS.Val.smul_ov(RHS.Val, Overflow), false); 730 else 731 Res = LHS.Val * RHS.Val; 732 break; 733 case tok::lessless: { 734 // Determine whether overflow is about to happen. 735 if (LHS.isUnsigned()) 736 Res = LHS.Val.ushl_ov(RHS.Val, Overflow); 737 else 738 Res = llvm::APSInt(LHS.Val.sshl_ov(RHS.Val, Overflow), false); 739 break; 740 } 741 case tok::greatergreater: { 742 // Determine whether overflow is about to happen. 743 unsigned ShAmt = static_cast<unsigned>(RHS.Val.getLimitedValue()); 744 if (ShAmt >= LHS.getBitWidth()) { 745 Overflow = true; 746 ShAmt = LHS.getBitWidth()-1; 747 } 748 Res = LHS.Val >> ShAmt; 749 break; 750 } 751 case tok::plus: 752 if (LHS.isUnsigned()) 753 Res = LHS.Val + RHS.Val; 754 else 755 Res = llvm::APSInt(LHS.Val.sadd_ov(RHS.Val, Overflow), false); 756 break; 757 case tok::minus: 758 if (LHS.isUnsigned()) 759 Res = LHS.Val - RHS.Val; 760 else 761 Res = llvm::APSInt(LHS.Val.ssub_ov(RHS.Val, Overflow), false); 762 break; 763 case tok::lessequal: 764 Res = LHS.Val <= RHS.Val; 765 Res.setIsUnsigned(false); // C99 6.5.8p6, result is always int (signed) 766 break; 767 case tok::less: 768 Res = LHS.Val < RHS.Val; 769 Res.setIsUnsigned(false); // C99 6.5.8p6, result is always int (signed) 770 break; 771 case tok::greaterequal: 772 Res = LHS.Val >= RHS.Val; 773 Res.setIsUnsigned(false); // C99 6.5.8p6, result is always int (signed) 774 break; 775 case tok::greater: 776 Res = LHS.Val > RHS.Val; 777 Res.setIsUnsigned(false); // C99 6.5.8p6, result is always int (signed) 778 break; 779 case tok::exclaimequal: 780 Res = LHS.Val != RHS.Val; 781 Res.setIsUnsigned(false); // C99 6.5.9p3, result is always int (signed) 782 break; 783 case tok::equalequal: 784 Res = LHS.Val == RHS.Val; 785 Res.setIsUnsigned(false); // C99 6.5.9p3, result is always int (signed) 786 break; 787 case tok::amp: 788 Res = LHS.Val & RHS.Val; 789 break; 790 case tok::caret: 791 Res = LHS.Val ^ RHS.Val; 792 break; 793 case tok::pipe: 794 Res = LHS.Val | RHS.Val; 795 break; 796 case tok::ampamp: 797 Res = (LHS.Val != 0 && RHS.Val != 0); 798 Res.setIsUnsigned(false); // C99 6.5.13p3, result is always int (signed) 799 break; 800 case tok::pipepipe: 801 Res = (LHS.Val != 0 || RHS.Val != 0); 802 Res.setIsUnsigned(false); // C99 6.5.14p3, result is always int (signed) 803 break; 804 case tok::comma: 805 // Comma is invalid in pp expressions in c89/c++ mode, but is valid in C99 806 // if not being evaluated. 807 if (!PP.getLangOpts().C99 || ValueLive) 808 PP.Diag(OpLoc, diag::ext_pp_comma_expr) 809 << LHS.getRange() << RHS.getRange(); 810 Res = RHS.Val; // LHS = LHS,RHS -> RHS. 811 break; 812 case tok::question: { 813 // Parse the : part of the expression. 814 if (PeekTok.isNot(tok::colon)) { 815 PP.Diag(PeekTok.getLocation(), diag::err_expected) 816 << tok::colon << LHS.getRange() << RHS.getRange(); 817 PP.Diag(OpLoc, diag::note_matching) << tok::question; 818 return true; 819 } 820 // Consume the :. 821 PP.LexNonComment(PeekTok); 822 823 // Evaluate the value after the :. 824 bool AfterColonLive = ValueLive && LHS.Val == 0; 825 PPValue AfterColonVal(LHS.getBitWidth()); 826 DefinedTracker DT; 827 if (EvaluateValue(AfterColonVal, PeekTok, DT, AfterColonLive, PP)) 828 return true; 829 830 // Parse anything after the : with the same precedence as ?. We allow 831 // things of equal precedence because ?: is right associative. 832 if (EvaluateDirectiveSubExpr(AfterColonVal, ThisPrec, 833 PeekTok, AfterColonLive, 834 IncludedUndefinedIds, PP)) 835 return true; 836 837 // Now that we have the condition, the LHS and the RHS of the :, evaluate. 838 Res = LHS.Val != 0 ? RHS.Val : AfterColonVal.Val; 839 RHS.setEnd(AfterColonVal.getRange().getEnd()); 840 841 // Usual arithmetic conversions (C99 6.3.1.8p1): result is unsigned if 842 // either operand is unsigned. 843 Res.setIsUnsigned(RHS.isUnsigned() || AfterColonVal.isUnsigned()); 844 845 // Figure out the precedence of the token after the : part. 846 PeekPrec = getPrecedence(PeekTok.getKind()); 847 break; 848 } 849 case tok::colon: 850 // Don't allow :'s to float around without being part of ?: exprs. 851 PP.Diag(OpLoc, diag::err_pp_colon_without_question) 852 << LHS.getRange() << RHS.getRange(); 853 return true; 854 } 855 856 // If this operator is live and overflowed, report the issue. 857 if (Overflow && ValueLive) 858 PP.Diag(OpLoc, diag::warn_pp_expr_overflow) 859 << LHS.getRange() << RHS.getRange(); 860 861 // Put the result back into 'LHS' for our next iteration. 862 LHS.Val = Res; 863 LHS.setEnd(RHS.getRange().getEnd()); 864 RHS.setIdentifier(nullptr); 865 } 866 } 867 868 /// EvaluateDirectiveExpression - Evaluate an integer constant expression that 869 /// may occur after a #if or #elif directive. If the expression is equivalent 870 /// to "!defined(X)" return X in IfNDefMacro. 871 Preprocessor::DirectiveEvalResult 872 Preprocessor::EvaluateDirectiveExpression(IdentifierInfo *&IfNDefMacro, 873 Token &Tok, bool &EvaluatedDefined, 874 bool CheckForEoD) { 875 SaveAndRestore PPDir(ParsingIfOrElifDirective, true); 876 // Save the current state of 'DisableMacroExpansion' and reset it to false. If 877 // 'DisableMacroExpansion' is true, then we must be in a macro argument list 878 // in which case a directive is undefined behavior. We want macros to be able 879 // to recursively expand in order to get more gcc-list behavior, so we force 880 // DisableMacroExpansion to false and restore it when we're done parsing the 881 // expression. 882 bool DisableMacroExpansionAtStartOfDirective = DisableMacroExpansion; 883 DisableMacroExpansion = false; 884 885 // Peek ahead one token. 886 LexNonComment(Tok); 887 888 // C99 6.10.1p3 - All expressions are evaluated as intmax_t or uintmax_t. 889 unsigned BitWidth = getTargetInfo().getIntMaxTWidth(); 890 891 PPValue ResVal(BitWidth); 892 DefinedTracker DT; 893 SourceLocation ExprStartLoc = SourceMgr.getExpansionLoc(Tok.getLocation()); 894 if (EvaluateValue(ResVal, Tok, DT, true, *this)) { 895 // Parse error, skip the rest of the macro line. 896 SourceRange ConditionRange = ExprStartLoc; 897 if (Tok.isNot(tok::eod)) 898 ConditionRange = DiscardUntilEndOfDirective(Tok); 899 900 // Restore 'DisableMacroExpansion'. 901 DisableMacroExpansion = DisableMacroExpansionAtStartOfDirective; 902 903 // We cannot trust the source range from the value because there was a 904 // parse error. Track the range manually -- the end of the directive is the 905 // end of the condition range. 906 return {std::nullopt, 907 false, 908 DT.IncludedUndefinedIds, 909 {ExprStartLoc, ConditionRange.getEnd()}}; 910 } 911 912 EvaluatedDefined = DT.State != DefinedTracker::Unknown; 913 914 // If we are at the end of the expression after just parsing a value, there 915 // must be no (unparenthesized) binary operators involved, so we can exit 916 // directly. 917 if (Tok.is(tok::eod)) { 918 // If the expression we parsed was of the form !defined(macro), return the 919 // macro in IfNDefMacro. 920 if (DT.State == DefinedTracker::NotDefinedMacro) 921 IfNDefMacro = DT.TheMacro; 922 923 // Restore 'DisableMacroExpansion'. 924 DisableMacroExpansion = DisableMacroExpansionAtStartOfDirective; 925 bool IsNonZero = ResVal.Val != 0; 926 SourceRange ValRange = ResVal.getRange(); 927 return {std::move(ResVal.Val), IsNonZero, DT.IncludedUndefinedIds, 928 ValRange}; 929 } 930 931 // Otherwise, we must have a binary operator (e.g. "#if 1 < 2"), so parse the 932 // operator and the stuff after it. 933 if (EvaluateDirectiveSubExpr(ResVal, getPrecedence(tok::question), 934 Tok, true, DT.IncludedUndefinedIds, *this)) { 935 // Parse error, skip the rest of the macro line. 936 if (Tok.isNot(tok::eod)) 937 DiscardUntilEndOfDirective(Tok); 938 939 // Restore 'DisableMacroExpansion'. 940 DisableMacroExpansion = DisableMacroExpansionAtStartOfDirective; 941 SourceRange ValRange = ResVal.getRange(); 942 return {std::nullopt, false, DT.IncludedUndefinedIds, ValRange}; 943 } 944 945 if (CheckForEoD) { 946 // If we aren't at the tok::eod token, something bad happened, like an extra 947 // ')' token. 948 if (Tok.isNot(tok::eod)) { 949 Diag(Tok, diag::err_pp_expected_eol); 950 DiscardUntilEndOfDirective(Tok); 951 } 952 } 953 954 EvaluatedDefined = EvaluatedDefined || DT.State != DefinedTracker::Unknown; 955 956 // Restore 'DisableMacroExpansion'. 957 DisableMacroExpansion = DisableMacroExpansionAtStartOfDirective; 958 bool IsNonZero = ResVal.Val != 0; 959 SourceRange ValRange = ResVal.getRange(); 960 return {std::move(ResVal.Val), IsNonZero, DT.IncludedUndefinedIds, ValRange}; 961 } 962 963 Preprocessor::DirectiveEvalResult 964 Preprocessor::EvaluateDirectiveExpression(IdentifierInfo *&IfNDefMacro, 965 bool CheckForEoD) { 966 Token Tok; 967 bool EvaluatedDefined; 968 return EvaluateDirectiveExpression(IfNDefMacro, Tok, EvaluatedDefined, 969 CheckForEoD); 970 } 971