SemaChecking.cpp revision 5caa370ea6f70bd3e7e4a9cc3b69ac1a849c8534
1//===--- SemaChecking.cpp - Extra Semantic Checking -----------------------===// 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 file implements extra semantic analysis beyond what is enforced 11// by the C type system. 12// 13//===----------------------------------------------------------------------===// 14 15#include "Sema.h" 16#include "clang/AST/ASTContext.h" 17#include "clang/AST/DeclObjC.h" 18#include "clang/AST/ExprCXX.h" 19#include "clang/AST/ExprObjC.h" 20#include "clang/Lex/LiteralSupport.h" 21#include "clang/Lex/Preprocessor.h" 22using namespace clang; 23 24/// getLocationOfStringLiteralByte - Return a source location that points to the 25/// specified byte of the specified string literal. 26/// 27/// Strings are amazingly complex. They can be formed from multiple tokens and 28/// can have escape sequences in them in addition to the usual trigraph and 29/// escaped newline business. This routine handles this complexity. 30/// 31SourceLocation Sema::getLocationOfStringLiteralByte(const StringLiteral *SL, 32 unsigned ByteNo) const { 33 assert(!SL->isWide() && "This doesn't work for wide strings yet"); 34 35 // Loop over all of the tokens in this string until we find the one that 36 // contains the byte we're looking for. 37 unsigned TokNo = 0; 38 while (1) { 39 assert(TokNo < SL->getNumConcatenated() && "Invalid byte number!"); 40 SourceLocation StrTokLoc = SL->getStrTokenLoc(TokNo); 41 42 // Get the spelling of the string so that we can get the data that makes up 43 // the string literal, not the identifier for the macro it is potentially 44 // expanded through. 45 SourceLocation StrTokSpellingLoc = SourceMgr.getSpellingLoc(StrTokLoc); 46 47 // Re-lex the token to get its length and original spelling. 48 std::pair<FileID, unsigned> LocInfo = 49 SourceMgr.getDecomposedLoc(StrTokSpellingLoc); 50 std::pair<const char *,const char *> Buffer = 51 SourceMgr.getBufferData(LocInfo.first); 52 const char *StrData = Buffer.first+LocInfo.second; 53 54 // Create a langops struct and enable trigraphs. This is sufficient for 55 // relexing tokens. 56 LangOptions LangOpts; 57 LangOpts.Trigraphs = true; 58 59 // Create a lexer starting at the beginning of this token. 60 Lexer TheLexer(StrTokSpellingLoc, LangOpts, Buffer.first, StrData, 61 Buffer.second); 62 Token TheTok; 63 TheLexer.LexFromRawLexer(TheTok); 64 65 // Use the StringLiteralParser to compute the length of the string in bytes. 66 StringLiteralParser SLP(&TheTok, 1, PP); 67 unsigned TokNumBytes = SLP.GetStringLength(); 68 69 // If the byte is in this token, return the location of the byte. 70 if (ByteNo < TokNumBytes || 71 (ByteNo == TokNumBytes && TokNo == SL->getNumConcatenated())) { 72 unsigned Offset = 73 StringLiteralParser::getOffsetOfStringByte(TheTok, ByteNo, PP); 74 75 // Now that we know the offset of the token in the spelling, use the 76 // preprocessor to get the offset in the original source. 77 return PP.AdvanceToTokenCharacter(StrTokLoc, Offset); 78 } 79 80 // Move to the next string token. 81 ++TokNo; 82 ByteNo -= TokNumBytes; 83 } 84} 85 86 87/// CheckFunctionCall - Check a direct function call for various correctness 88/// and safety properties not strictly enforced by the C type system. 89Action::OwningExprResult 90Sema::CheckFunctionCall(FunctionDecl *FDecl, CallExpr *TheCall) { 91 OwningExprResult TheCallResult(Owned(TheCall)); 92 // Get the IdentifierInfo* for the called function. 93 IdentifierInfo *FnInfo = FDecl->getIdentifier(); 94 95 // None of the checks below are needed for functions that don't have 96 // simple names (e.g., C++ conversion functions). 97 if (!FnInfo) 98 return move(TheCallResult); 99 100 switch (FDecl->getBuiltinID(Context)) { 101 case Builtin::BI__builtin___CFStringMakeConstantString: 102 assert(TheCall->getNumArgs() == 1 && 103 "Wrong # arguments to builtin CFStringMakeConstantString"); 104 if (CheckObjCString(TheCall->getArg(0))) 105 return ExprError(); 106 return move(TheCallResult); 107 case Builtin::BI__builtin_stdarg_start: 108 case Builtin::BI__builtin_va_start: 109 if (SemaBuiltinVAStart(TheCall)) 110 return ExprError(); 111 return move(TheCallResult); 112 case Builtin::BI__builtin_isgreater: 113 case Builtin::BI__builtin_isgreaterequal: 114 case Builtin::BI__builtin_isless: 115 case Builtin::BI__builtin_islessequal: 116 case Builtin::BI__builtin_islessgreater: 117 case Builtin::BI__builtin_isunordered: 118 if (SemaBuiltinUnorderedCompare(TheCall)) 119 return ExprError(); 120 return move(TheCallResult); 121 case Builtin::BI__builtin_return_address: 122 case Builtin::BI__builtin_frame_address: 123 if (SemaBuiltinStackAddress(TheCall)) 124 return ExprError(); 125 return move(TheCallResult); 126 case Builtin::BI__builtin_shufflevector: 127 return SemaBuiltinShuffleVector(TheCall); 128 // TheCall will be freed by the smart pointer here, but that's fine, since 129 // SemaBuiltinShuffleVector guts it, but then doesn't release it. 130 case Builtin::BI__builtin_prefetch: 131 if (SemaBuiltinPrefetch(TheCall)) 132 return ExprError(); 133 return move(TheCallResult); 134 case Builtin::BI__builtin_object_size: 135 if (SemaBuiltinObjectSize(TheCall)) 136 return ExprError(); 137 return move(TheCallResult); 138 case Builtin::BI__builtin_longjmp: 139 if (SemaBuiltinLongjmp(TheCall)) 140 return ExprError(); 141 return move(TheCallResult); 142 case Builtin::BI__sync_fetch_and_add: 143 case Builtin::BI__sync_fetch_and_sub: 144 case Builtin::BI__sync_fetch_and_or: 145 case Builtin::BI__sync_fetch_and_and: 146 case Builtin::BI__sync_fetch_and_xor: 147 case Builtin::BI__sync_add_and_fetch: 148 case Builtin::BI__sync_sub_and_fetch: 149 case Builtin::BI__sync_and_and_fetch: 150 case Builtin::BI__sync_or_and_fetch: 151 case Builtin::BI__sync_xor_and_fetch: 152 case Builtin::BI__sync_val_compare_and_swap: 153 case Builtin::BI__sync_bool_compare_and_swap: 154 case Builtin::BI__sync_lock_test_and_set: 155 case Builtin::BI__sync_lock_release: 156 if (SemaBuiltinAtomicOverloaded(TheCall)) 157 return ExprError(); 158 return move(TheCallResult); 159 } 160 161 // FIXME: This mechanism should be abstracted to be less fragile and 162 // more efficient. For example, just map function ids to custom 163 // handlers. 164 165 // Printf checking. 166 if (const FormatAttr *Format = FDecl->getAttr<FormatAttr>()) { 167 if (Format->getType() == "printf") { 168 bool HasVAListArg = Format->getFirstArg() == 0; 169 if (!HasVAListArg) { 170 if (const FunctionProtoType *Proto 171 = FDecl->getType()->getAsFunctionProtoType()) 172 HasVAListArg = !Proto->isVariadic(); 173 } 174 CheckPrintfArguments(TheCall, HasVAListArg, Format->getFormatIdx() - 1, 175 HasVAListArg ? 0 : Format->getFirstArg() - 1); 176 } 177 } 178 179 return move(TheCallResult); 180} 181 182/// SemaBuiltinAtomicOverloaded - We have a call to a function like 183/// __sync_fetch_and_add, which is an overloaded function based on the pointer 184/// type of its first argument. The main ActOnCallExpr routines have already 185/// promoted the types of arguments because all of these calls are prototyped as 186/// void(...). 187/// 188/// This function goes through and does final semantic checking for these 189/// builtins, 190bool Sema::SemaBuiltinAtomicOverloaded(CallExpr *TheCall) { 191 DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts()); 192 FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl()); 193 194 // Ensure that we have at least one argument to do type inference from. 195 if (TheCall->getNumArgs() < 1) 196 return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args) 197 << 0 << TheCall->getCallee()->getSourceRange(); 198 199 // Inspect the first argument of the atomic builtin. This should always be 200 // a pointer type, whose element is an integral scalar or pointer type. 201 // Because it is a pointer type, we don't have to worry about any implicit 202 // casts here. 203 Expr *FirstArg = TheCall->getArg(0); 204 if (!FirstArg->getType()->isPointerType()) 205 return Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer) 206 << FirstArg->getType() << FirstArg->getSourceRange(); 207 208 QualType ValType = FirstArg->getType()->getAsPointerType()->getPointeeType(); 209 if (!ValType->isIntegerType() && !ValType->isPointerType() && 210 !ValType->isBlockPointerType()) 211 return Diag(DRE->getLocStart(), 212 diag::err_atomic_builtin_must_be_pointer_intptr) 213 << FirstArg->getType() << FirstArg->getSourceRange(); 214 215 // We need to figure out which concrete builtin this maps onto. For example, 216 // __sync_fetch_and_add with a 2 byte object turns into 217 // __sync_fetch_and_add_2. 218#define BUILTIN_ROW(x) \ 219 { Builtin::BI##x##_1, Builtin::BI##x##_2, Builtin::BI##x##_4, \ 220 Builtin::BI##x##_8, Builtin::BI##x##_16 } 221 222 static const unsigned BuiltinIndices[][5] = { 223 BUILTIN_ROW(__sync_fetch_and_add), 224 BUILTIN_ROW(__sync_fetch_and_sub), 225 BUILTIN_ROW(__sync_fetch_and_or), 226 BUILTIN_ROW(__sync_fetch_and_and), 227 BUILTIN_ROW(__sync_fetch_and_xor), 228 229 BUILTIN_ROW(__sync_add_and_fetch), 230 BUILTIN_ROW(__sync_sub_and_fetch), 231 BUILTIN_ROW(__sync_and_and_fetch), 232 BUILTIN_ROW(__sync_or_and_fetch), 233 BUILTIN_ROW(__sync_xor_and_fetch), 234 235 BUILTIN_ROW(__sync_val_compare_and_swap), 236 BUILTIN_ROW(__sync_bool_compare_and_swap), 237 BUILTIN_ROW(__sync_lock_test_and_set), 238 BUILTIN_ROW(__sync_lock_release) 239 }; 240#undef BUILTIN_ROW 241 242 // Determine the index of the size. 243 unsigned SizeIndex; 244 switch (Context.getTypeSize(ValType)/8) { 245 case 1: SizeIndex = 0; break; 246 case 2: SizeIndex = 1; break; 247 case 4: SizeIndex = 2; break; 248 case 8: SizeIndex = 3; break; 249 case 16: SizeIndex = 4; break; 250 default: 251 return Diag(DRE->getLocStart(), diag::err_atomic_builtin_pointer_size) 252 << FirstArg->getType() << FirstArg->getSourceRange(); 253 } 254 255 // Each of these builtins has one pointer argument, followed by some number of 256 // values (0, 1 or 2) followed by a potentially empty varags list of stuff 257 // that we ignore. Find out which row of BuiltinIndices to read from as well 258 // as the number of fixed args. 259 unsigned BuiltinID = FDecl->getBuiltinID(Context); 260 unsigned BuiltinIndex, NumFixed = 1; 261 switch (BuiltinID) { 262 default: assert(0 && "Unknown overloaded atomic builtin!"); 263 case Builtin::BI__sync_fetch_and_add: BuiltinIndex = 0; break; 264 case Builtin::BI__sync_fetch_and_sub: BuiltinIndex = 1; break; 265 case Builtin::BI__sync_fetch_and_or: BuiltinIndex = 2; break; 266 case Builtin::BI__sync_fetch_and_and: BuiltinIndex = 3; break; 267 case Builtin::BI__sync_fetch_and_xor: BuiltinIndex = 4; break; 268 269 case Builtin::BI__sync_add_and_fetch: BuiltinIndex = 5; break; 270 case Builtin::BI__sync_sub_and_fetch: BuiltinIndex = 6; break; 271 case Builtin::BI__sync_and_and_fetch: BuiltinIndex = 7; break; 272 case Builtin::BI__sync_or_and_fetch: BuiltinIndex = 8; break; 273 case Builtin::BI__sync_xor_and_fetch: BuiltinIndex = 9; break; 274 275 case Builtin::BI__sync_val_compare_and_swap: 276 BuiltinIndex = 10; 277 NumFixed = 2; 278 break; 279 case Builtin::BI__sync_bool_compare_and_swap: 280 BuiltinIndex = 11; 281 NumFixed = 2; 282 break; 283 case Builtin::BI__sync_lock_test_and_set: BuiltinIndex = 12; break; 284 case Builtin::BI__sync_lock_release: 285 BuiltinIndex = 13; 286 NumFixed = 0; 287 break; 288 } 289 290 // Now that we know how many fixed arguments we expect, first check that we 291 // have at least that many. 292 if (TheCall->getNumArgs() < 1+NumFixed) 293 return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args) 294 << 0 << TheCall->getCallee()->getSourceRange(); 295 296 // Next, walk the valid ones promoting to the right type. 297 for (unsigned i = 0; i != NumFixed; ++i) { 298 Expr *Arg = TheCall->getArg(i+1); 299 300 // If the argument is an implicit cast, then there was a promotion due to 301 // "...", just remove it now. 302 if (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Arg)) { 303 Arg = ICE->getSubExpr(); 304 ICE->setSubExpr(0); 305 ICE->Destroy(Context); 306 TheCall->setArg(i+1, Arg); 307 } 308 309 // GCC does an implicit conversion to the pointer or integer ValType. This 310 // can fail in some cases (1i -> int**), check for this error case now. 311 if (CheckCastTypes(Arg->getSourceRange(), ValType, Arg)) 312 return true; 313 314 // Okay, we have something that *can* be converted to the right type. Check 315 // to see if there is a potentially weird extension going on here. This can 316 // happen when you do an atomic operation on something like an char* and 317 // pass in 42. The 42 gets converted to char. This is even more strange 318 // for things like 45.123 -> char, etc. 319 // FIXME: Do this check. 320 ImpCastExprToType(Arg, ValType, false); 321 TheCall->setArg(i+1, Arg); 322 } 323 324 // Okay, if we get here, everything is good. Get the decl for the concrete 325 // builtin. 326 unsigned NewBuiltinID = BuiltinIndices[BuiltinIndex][SizeIndex]; 327 const char *NewBuiltinName = Context.BuiltinInfo.GetName(NewBuiltinID); 328 IdentifierInfo *NewBuiltinII = PP.getIdentifierInfo(NewBuiltinName); 329 FunctionDecl *NewBuiltinDecl = 330 cast<FunctionDecl>(LazilyCreateBuiltin(NewBuiltinII, NewBuiltinID, 331 TUScope, false, DRE->getLocStart())); 332 // Switch the DeclRefExpr to refer to the new decl. 333 DRE->setDecl(NewBuiltinDecl); 334 DRE->setType(NewBuiltinDecl->getType()); 335 336 // Set the callee in the CallExpr. 337 // FIXME: This leaks the original parens and implicit casts. 338 Expr *PromotedCall = DRE; 339 UsualUnaryConversions(PromotedCall); 340 TheCall->setCallee(PromotedCall); 341 342 343 // Change the result type of the call to match the result type of the decl. 344 TheCall->setType(NewBuiltinDecl->getResultType()); 345 return false; 346} 347 348 349/// CheckObjCString - Checks that the argument to the builtin 350/// CFString constructor is correct 351/// FIXME: GCC currently emits the following warning: 352/// "warning: input conversion stopped due to an input byte that does not 353/// belong to the input codeset UTF-8" 354/// Note: It might also make sense to do the UTF-16 conversion here (would 355/// simplify the backend). 356bool Sema::CheckObjCString(Expr *Arg) { 357 Arg = Arg->IgnoreParenCasts(); 358 StringLiteral *Literal = dyn_cast<StringLiteral>(Arg); 359 360 if (!Literal || Literal->isWide()) { 361 Diag(Arg->getLocStart(), diag::err_cfstring_literal_not_string_constant) 362 << Arg->getSourceRange(); 363 return true; 364 } 365 366 const char *Data = Literal->getStrData(); 367 unsigned Length = Literal->getByteLength(); 368 369 for (unsigned i = 0; i < Length; ++i) { 370 if (!Data[i]) { 371 Diag(getLocationOfStringLiteralByte(Literal, i), 372 diag::warn_cfstring_literal_contains_nul_character) 373 << Arg->getSourceRange(); 374 break; 375 } 376 } 377 378 return false; 379} 380 381/// SemaBuiltinVAStart - Check the arguments to __builtin_va_start for validity. 382/// Emit an error and return true on failure, return false on success. 383bool Sema::SemaBuiltinVAStart(CallExpr *TheCall) { 384 Expr *Fn = TheCall->getCallee(); 385 if (TheCall->getNumArgs() > 2) { 386 Diag(TheCall->getArg(2)->getLocStart(), 387 diag::err_typecheck_call_too_many_args) 388 << 0 /*function call*/ << Fn->getSourceRange() 389 << SourceRange(TheCall->getArg(2)->getLocStart(), 390 (*(TheCall->arg_end()-1))->getLocEnd()); 391 return true; 392 } 393 394 if (TheCall->getNumArgs() < 2) { 395 return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args) 396 << 0 /*function call*/; 397 } 398 399 // Determine whether the current function is variadic or not. 400 bool isVariadic; 401 if (CurBlock) 402 isVariadic = CurBlock->isVariadic; 403 else if (getCurFunctionDecl()) { 404 if (FunctionProtoType* FTP = 405 dyn_cast<FunctionProtoType>(getCurFunctionDecl()->getType())) 406 isVariadic = FTP->isVariadic(); 407 else 408 isVariadic = false; 409 } else { 410 isVariadic = getCurMethodDecl()->isVariadic(); 411 } 412 413 if (!isVariadic) { 414 Diag(Fn->getLocStart(), diag::err_va_start_used_in_non_variadic_function); 415 return true; 416 } 417 418 // Verify that the second argument to the builtin is the last argument of the 419 // current function or method. 420 bool SecondArgIsLastNamedArgument = false; 421 const Expr *Arg = TheCall->getArg(1)->IgnoreParenCasts(); 422 423 if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Arg)) { 424 if (const ParmVarDecl *PV = dyn_cast<ParmVarDecl>(DR->getDecl())) { 425 // FIXME: This isn't correct for methods (results in bogus warning). 426 // Get the last formal in the current function. 427 const ParmVarDecl *LastArg; 428 if (CurBlock) 429 LastArg = *(CurBlock->TheDecl->param_end()-1); 430 else if (FunctionDecl *FD = getCurFunctionDecl()) 431 LastArg = *(FD->param_end()-1); 432 else 433 LastArg = *(getCurMethodDecl()->param_end()-1); 434 SecondArgIsLastNamedArgument = PV == LastArg; 435 } 436 } 437 438 if (!SecondArgIsLastNamedArgument) 439 Diag(TheCall->getArg(1)->getLocStart(), 440 diag::warn_second_parameter_of_va_start_not_last_named_argument); 441 return false; 442} 443 444/// SemaBuiltinUnorderedCompare - Handle functions like __builtin_isgreater and 445/// friends. This is declared to take (...), so we have to check everything. 446bool Sema::SemaBuiltinUnorderedCompare(CallExpr *TheCall) { 447 if (TheCall->getNumArgs() < 2) 448 return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args) 449 << 0 /*function call*/; 450 if (TheCall->getNumArgs() > 2) 451 return Diag(TheCall->getArg(2)->getLocStart(), 452 diag::err_typecheck_call_too_many_args) 453 << 0 /*function call*/ 454 << SourceRange(TheCall->getArg(2)->getLocStart(), 455 (*(TheCall->arg_end()-1))->getLocEnd()); 456 457 Expr *OrigArg0 = TheCall->getArg(0); 458 Expr *OrigArg1 = TheCall->getArg(1); 459 460 // Do standard promotions between the two arguments, returning their common 461 // type. 462 QualType Res = UsualArithmeticConversions(OrigArg0, OrigArg1, false); 463 464 // Make sure any conversions are pushed back into the call; this is 465 // type safe since unordered compare builtins are declared as "_Bool 466 // foo(...)". 467 TheCall->setArg(0, OrigArg0); 468 TheCall->setArg(1, OrigArg1); 469 470 // If the common type isn't a real floating type, then the arguments were 471 // invalid for this operation. 472 if (!Res->isRealFloatingType()) 473 return Diag(OrigArg0->getLocStart(), 474 diag::err_typecheck_call_invalid_ordered_compare) 475 << OrigArg0->getType() << OrigArg1->getType() 476 << SourceRange(OrigArg0->getLocStart(), OrigArg1->getLocEnd()); 477 478 return false; 479} 480 481bool Sema::SemaBuiltinStackAddress(CallExpr *TheCall) { 482 // The signature for these builtins is exact; the only thing we need 483 // to check is that the argument is a constant. 484 SourceLocation Loc; 485 if (!TheCall->getArg(0)->isIntegerConstantExpr(Context, &Loc)) 486 return Diag(Loc, diag::err_stack_const_level) << TheCall->getSourceRange(); 487 488 return false; 489} 490 491/// SemaBuiltinShuffleVector - Handle __builtin_shufflevector. 492// This is declared to take (...), so we have to check everything. 493Action::OwningExprResult Sema::SemaBuiltinShuffleVector(CallExpr *TheCall) { 494 if (TheCall->getNumArgs() < 3) 495 return ExprError(Diag(TheCall->getLocEnd(), 496 diag::err_typecheck_call_too_few_args) 497 << 0 /*function call*/ << TheCall->getSourceRange()); 498 499 QualType FAType = TheCall->getArg(0)->getType(); 500 QualType SAType = TheCall->getArg(1)->getType(); 501 502 if (!FAType->isVectorType() || !SAType->isVectorType()) { 503 Diag(TheCall->getLocStart(), diag::err_shufflevector_non_vector) 504 << SourceRange(TheCall->getArg(0)->getLocStart(), 505 TheCall->getArg(1)->getLocEnd()); 506 return ExprError(); 507 } 508 509 if (Context.getCanonicalType(FAType).getUnqualifiedType() != 510 Context.getCanonicalType(SAType).getUnqualifiedType()) { 511 Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector) 512 << SourceRange(TheCall->getArg(0)->getLocStart(), 513 TheCall->getArg(1)->getLocEnd()); 514 return ExprError(); 515 } 516 517 unsigned numElements = FAType->getAsVectorType()->getNumElements(); 518 if (TheCall->getNumArgs() != numElements+2) { 519 if (TheCall->getNumArgs() < numElements+2) 520 return ExprError(Diag(TheCall->getLocEnd(), 521 diag::err_typecheck_call_too_few_args) 522 << 0 /*function call*/ << TheCall->getSourceRange()); 523 return ExprError(Diag(TheCall->getLocEnd(), 524 diag::err_typecheck_call_too_many_args) 525 << 0 /*function call*/ << TheCall->getSourceRange()); 526 } 527 528 for (unsigned i = 2; i < TheCall->getNumArgs(); i++) { 529 llvm::APSInt Result(32); 530 if (!TheCall->getArg(i)->isIntegerConstantExpr(Result, Context)) 531 return ExprError(Diag(TheCall->getLocStart(), 532 diag::err_shufflevector_nonconstant_argument) 533 << TheCall->getArg(i)->getSourceRange()); 534 535 if (Result.getActiveBits() > 64 || Result.getZExtValue() >= numElements*2) 536 return ExprError(Diag(TheCall->getLocStart(), 537 diag::err_shufflevector_argument_too_large) 538 << TheCall->getArg(i)->getSourceRange()); 539 } 540 541 llvm::SmallVector<Expr*, 32> exprs; 542 543 for (unsigned i = 0, e = TheCall->getNumArgs(); i != e; i++) { 544 exprs.push_back(TheCall->getArg(i)); 545 TheCall->setArg(i, 0); 546 } 547 548 return Owned(new (Context) ShuffleVectorExpr(exprs.begin(), numElements+2, 549 FAType, 550 TheCall->getCallee()->getLocStart(), 551 TheCall->getRParenLoc())); 552} 553 554/// SemaBuiltinPrefetch - Handle __builtin_prefetch. 555// This is declared to take (const void*, ...) and can take two 556// optional constant int args. 557bool Sema::SemaBuiltinPrefetch(CallExpr *TheCall) { 558 unsigned NumArgs = TheCall->getNumArgs(); 559 560 if (NumArgs > 3) 561 return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_many_args) 562 << 0 /*function call*/ << TheCall->getSourceRange(); 563 564 // Argument 0 is checked for us and the remaining arguments must be 565 // constant integers. 566 for (unsigned i = 1; i != NumArgs; ++i) { 567 Expr *Arg = TheCall->getArg(i); 568 QualType RWType = Arg->getType(); 569 570 const BuiltinType *BT = RWType->getAsBuiltinType(); 571 llvm::APSInt Result; 572 if (!BT || BT->getKind() != BuiltinType::Int || 573 !Arg->isIntegerConstantExpr(Result, Context)) 574 return Diag(TheCall->getLocStart(), diag::err_prefetch_invalid_argument) 575 << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); 576 577 // FIXME: gcc issues a warning and rewrites these to 0. These 578 // seems especially odd for the third argument since the default 579 // is 3. 580 if (i == 1) { 581 if (Result.getSExtValue() < 0 || Result.getSExtValue() > 1) 582 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 583 << "0" << "1" << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); 584 } else { 585 if (Result.getSExtValue() < 0 || Result.getSExtValue() > 3) 586 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 587 << "0" << "3" << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); 588 } 589 } 590 591 return false; 592} 593 594/// SemaBuiltinObjectSize - Handle __builtin_object_size(void *ptr, 595/// int type). This simply type checks that type is one of the defined 596/// constants (0-3). 597bool Sema::SemaBuiltinObjectSize(CallExpr *TheCall) { 598 Expr *Arg = TheCall->getArg(1); 599 QualType ArgType = Arg->getType(); 600 const BuiltinType *BT = ArgType->getAsBuiltinType(); 601 llvm::APSInt Result(32); 602 if (!BT || BT->getKind() != BuiltinType::Int || 603 !Arg->isIntegerConstantExpr(Result, Context)) { 604 return Diag(TheCall->getLocStart(), diag::err_object_size_invalid_argument) 605 << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); 606 } 607 608 if (Result.getSExtValue() < 0 || Result.getSExtValue() > 3) { 609 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 610 << "0" << "3" << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); 611 } 612 613 return false; 614} 615 616/// SemaBuiltinLongjmp - Handle __builtin_longjmp(void *env[5], int val). 617/// This checks that val is a constant 1. 618bool Sema::SemaBuiltinLongjmp(CallExpr *TheCall) { 619 Expr *Arg = TheCall->getArg(1); 620 llvm::APSInt Result(32); 621 if (!Arg->isIntegerConstantExpr(Result, Context) || Result != 1) 622 return Diag(TheCall->getLocStart(), diag::err_builtin_longjmp_invalid_val) 623 << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); 624 625 return false; 626} 627 628// Handle i > 1 ? "x" : "y", recursivelly 629bool Sema::SemaCheckStringLiteral(const Expr *E, const CallExpr *TheCall, 630 bool HasVAListArg, 631 unsigned format_idx, unsigned firstDataArg) { 632 633 switch (E->getStmtClass()) { 634 case Stmt::ConditionalOperatorClass: { 635 const ConditionalOperator *C = cast<ConditionalOperator>(E); 636 return SemaCheckStringLiteral(C->getLHS(), TheCall, 637 HasVAListArg, format_idx, firstDataArg) 638 && SemaCheckStringLiteral(C->getRHS(), TheCall, 639 HasVAListArg, format_idx, firstDataArg); 640 } 641 642 case Stmt::ImplicitCastExprClass: { 643 const ImplicitCastExpr *Expr = cast<ImplicitCastExpr>(E); 644 return SemaCheckStringLiteral(Expr->getSubExpr(), TheCall, HasVAListArg, 645 format_idx, firstDataArg); 646 } 647 648 case Stmt::ParenExprClass: { 649 const ParenExpr *Expr = cast<ParenExpr>(E); 650 return SemaCheckStringLiteral(Expr->getSubExpr(), TheCall, HasVAListArg, 651 format_idx, firstDataArg); 652 } 653 654 case Stmt::DeclRefExprClass: { 655 const DeclRefExpr *DR = cast<DeclRefExpr>(E); 656 657 // As an exception, do not flag errors for variables binding to 658 // const string literals. 659 if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) { 660 bool isConstant = false; 661 QualType T = DR->getType(); 662 663 if (const ArrayType *AT = Context.getAsArrayType(T)) { 664 isConstant = AT->getElementType().isConstant(Context); 665 } 666 else if (const PointerType *PT = T->getAsPointerType()) { 667 isConstant = T.isConstant(Context) && 668 PT->getPointeeType().isConstant(Context); 669 } 670 671 if (isConstant) { 672 const VarDecl *Def = 0; 673 if (const Expr *Init = VD->getDefinition(Def)) 674 return SemaCheckStringLiteral(Init, TheCall, 675 HasVAListArg, format_idx, firstDataArg); 676 } 677 } 678 679 return false; 680 } 681 682 case Stmt::ObjCStringLiteralClass: 683 case Stmt::StringLiteralClass: { 684 const StringLiteral *StrE = NULL; 685 686 if (const ObjCStringLiteral *ObjCFExpr = dyn_cast<ObjCStringLiteral>(E)) 687 StrE = ObjCFExpr->getString(); 688 else 689 StrE = cast<StringLiteral>(E); 690 691 if (StrE) { 692 CheckPrintfString(StrE, E, TheCall, HasVAListArg, format_idx, 693 firstDataArg); 694 return true; 695 } 696 697 return false; 698 } 699 700 default: 701 return false; 702 } 703} 704 705 706/// CheckPrintfArguments - Check calls to printf (and similar functions) for 707/// correct use of format strings. 708/// 709/// HasVAListArg - A predicate indicating whether the printf-like 710/// function is passed an explicit va_arg argument (e.g., vprintf) 711/// 712/// format_idx - The index into Args for the format string. 713/// 714/// Improper format strings to functions in the printf family can be 715/// the source of bizarre bugs and very serious security holes. A 716/// good source of information is available in the following paper 717/// (which includes additional references): 718/// 719/// FormatGuard: Automatic Protection From printf Format String 720/// Vulnerabilities, Proceedings of the 10th USENIX Security Symposium, 2001. 721/// 722/// Functionality implemented: 723/// 724/// We can statically check the following properties for string 725/// literal format strings for non v.*printf functions (where the 726/// arguments are passed directly): 727// 728/// (1) Are the number of format conversions equal to the number of 729/// data arguments? 730/// 731/// (2) Does each format conversion correctly match the type of the 732/// corresponding data argument? (TODO) 733/// 734/// Moreover, for all printf functions we can: 735/// 736/// (3) Check for a missing format string (when not caught by type checking). 737/// 738/// (4) Check for no-operation flags; e.g. using "#" with format 739/// conversion 'c' (TODO) 740/// 741/// (5) Check the use of '%n', a major source of security holes. 742/// 743/// (6) Check for malformed format conversions that don't specify anything. 744/// 745/// (7) Check for empty format strings. e.g: printf(""); 746/// 747/// (8) Check that the format string is a wide literal. 748/// 749/// (9) Also check the arguments of functions with the __format__ attribute. 750/// (TODO). 751/// 752/// All of these checks can be done by parsing the format string. 753/// 754/// For now, we ONLY do (1), (3), (5), (6), (7), and (8). 755void 756Sema::CheckPrintfArguments(const CallExpr *TheCall, bool HasVAListArg, 757 unsigned format_idx, unsigned firstDataArg) { 758 const Expr *Fn = TheCall->getCallee(); 759 760 // CHECK: printf-like function is called with no format string. 761 if (format_idx >= TheCall->getNumArgs()) { 762 Diag(TheCall->getRParenLoc(), diag::warn_printf_missing_format_string) 763 << Fn->getSourceRange(); 764 return; 765 } 766 767 const Expr *OrigFormatExpr = TheCall->getArg(format_idx)->IgnoreParenCasts(); 768 769 // CHECK: format string is not a string literal. 770 // 771 // Dynamically generated format strings are difficult to 772 // automatically vet at compile time. Requiring that format strings 773 // are string literals: (1) permits the checking of format strings by 774 // the compiler and thereby (2) can practically remove the source of 775 // many format string exploits. 776 777 // Format string can be either ObjC string (e.g. @"%d") or 778 // C string (e.g. "%d") 779 // ObjC string uses the same format specifiers as C string, so we can use 780 // the same format string checking logic for both ObjC and C strings. 781 if (SemaCheckStringLiteral(OrigFormatExpr, TheCall, HasVAListArg, format_idx, 782 firstDataArg)) 783 return; // Literal format string found, check done! 784 785 // For vprintf* functions (i.e., HasVAListArg==true), we add a 786 // special check to see if the format string is a function parameter 787 // of the function calling the printf function. If the function 788 // has an attribute indicating it is a printf-like function, then we 789 // should suppress warnings concerning non-literals being used in a call 790 // to a vprintf function. For example: 791 // 792 // void 793 // logmessage(char const *fmt __attribute__ (format (printf, 1, 2)), ...) { 794 // va_list ap; 795 // va_start(ap, fmt); 796 // vprintf(fmt, ap); // Do NOT emit a warning about "fmt". 797 // ... 798 // 799 // 800 // FIXME: We don't have full attribute support yet, so just check to see 801 // if the argument is a DeclRefExpr that references a parameter. We'll 802 // add proper support for checking the attribute later. 803 if (HasVAListArg) 804 if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(OrigFormatExpr)) 805 if (isa<ParmVarDecl>(DR->getDecl())) 806 return; 807 808 // If there are no arguments specified, warn with -Wformat-security, otherwise 809 // warn only with -Wformat-nonliteral. 810 if (TheCall->getNumArgs() == format_idx+1) 811 Diag(TheCall->getArg(format_idx)->getLocStart(), 812 diag::warn_printf_nonliteral_noargs) 813 << OrigFormatExpr->getSourceRange(); 814 else 815 Diag(TheCall->getArg(format_idx)->getLocStart(), 816 diag::warn_printf_nonliteral) 817 << OrigFormatExpr->getSourceRange(); 818} 819 820void Sema::CheckPrintfString(const StringLiteral *FExpr, 821 const Expr *OrigFormatExpr, 822 const CallExpr *TheCall, bool HasVAListArg, 823 unsigned format_idx, unsigned firstDataArg) { 824 825 const ObjCStringLiteral *ObjCFExpr = 826 dyn_cast<ObjCStringLiteral>(OrigFormatExpr); 827 828 // CHECK: is the format string a wide literal? 829 if (FExpr->isWide()) { 830 Diag(FExpr->getLocStart(), 831 diag::warn_printf_format_string_is_wide_literal) 832 << OrigFormatExpr->getSourceRange(); 833 return; 834 } 835 836 // Str - The format string. NOTE: this is NOT null-terminated! 837 const char *Str = FExpr->getStrData(); 838 839 // CHECK: empty format string? 840 unsigned StrLen = FExpr->getByteLength(); 841 842 if (StrLen == 0) { 843 Diag(FExpr->getLocStart(), diag::warn_printf_empty_format_string) 844 << OrigFormatExpr->getSourceRange(); 845 return; 846 } 847 848 // We process the format string using a binary state machine. The 849 // current state is stored in CurrentState. 850 enum { 851 state_OrdChr, 852 state_Conversion 853 } CurrentState = state_OrdChr; 854 855 // numConversions - The number of conversions seen so far. This is 856 // incremented as we traverse the format string. 857 unsigned numConversions = 0; 858 859 // numDataArgs - The number of data arguments after the format 860 // string. This can only be determined for non vprintf-like 861 // functions. For those functions, this value is 1 (the sole 862 // va_arg argument). 863 unsigned numDataArgs = TheCall->getNumArgs()-firstDataArg; 864 865 // Inspect the format string. 866 unsigned StrIdx = 0; 867 868 // LastConversionIdx - Index within the format string where we last saw 869 // a '%' character that starts a new format conversion. 870 unsigned LastConversionIdx = 0; 871 872 for (; StrIdx < StrLen; ++StrIdx) { 873 874 // Is the number of detected conversion conversions greater than 875 // the number of matching data arguments? If so, stop. 876 if (!HasVAListArg && numConversions > numDataArgs) break; 877 878 // Handle "\0" 879 if (Str[StrIdx] == '\0') { 880 // The string returned by getStrData() is not null-terminated, 881 // so the presence of a null character is likely an error. 882 Diag(getLocationOfStringLiteralByte(FExpr, StrIdx), 883 diag::warn_printf_format_string_contains_null_char) 884 << OrigFormatExpr->getSourceRange(); 885 return; 886 } 887 888 // Ordinary characters (not processing a format conversion). 889 if (CurrentState == state_OrdChr) { 890 if (Str[StrIdx] == '%') { 891 CurrentState = state_Conversion; 892 LastConversionIdx = StrIdx; 893 } 894 continue; 895 } 896 897 // Seen '%'. Now processing a format conversion. 898 switch (Str[StrIdx]) { 899 // Handle dynamic precision or width specifier. 900 case '*': { 901 ++numConversions; 902 903 if (!HasVAListArg && numConversions > numDataArgs) { 904 SourceLocation Loc = getLocationOfStringLiteralByte(FExpr, StrIdx); 905 906 if (Str[StrIdx-1] == '.') 907 Diag(Loc, diag::warn_printf_asterisk_precision_missing_arg) 908 << OrigFormatExpr->getSourceRange(); 909 else 910 Diag(Loc, diag::warn_printf_asterisk_width_missing_arg) 911 << OrigFormatExpr->getSourceRange(); 912 913 // Don't do any more checking. We'll just emit spurious errors. 914 return; 915 } 916 917 // Perform type checking on width/precision specifier. 918 const Expr *E = TheCall->getArg(format_idx+numConversions); 919 if (const BuiltinType *BT = E->getType()->getAsBuiltinType()) 920 if (BT->getKind() == BuiltinType::Int) 921 break; 922 923 SourceLocation Loc = getLocationOfStringLiteralByte(FExpr, StrIdx); 924 925 if (Str[StrIdx-1] == '.') 926 Diag(Loc, diag::warn_printf_asterisk_precision_wrong_type) 927 << E->getType() << E->getSourceRange(); 928 else 929 Diag(Loc, diag::warn_printf_asterisk_width_wrong_type) 930 << E->getType() << E->getSourceRange(); 931 932 break; 933 } 934 935 // Characters which can terminate a format conversion 936 // (e.g. "%d"). Characters that specify length modifiers or 937 // other flags are handled by the default case below. 938 // 939 // FIXME: additional checks will go into the following cases. 940 case 'i': 941 case 'd': 942 case 'o': 943 case 'u': 944 case 'x': 945 case 'X': 946 case 'D': 947 case 'O': 948 case 'U': 949 case 'e': 950 case 'E': 951 case 'f': 952 case 'F': 953 case 'g': 954 case 'G': 955 case 'a': 956 case 'A': 957 case 'c': 958 case 'C': 959 case 'S': 960 case 's': 961 case 'p': 962 ++numConversions; 963 CurrentState = state_OrdChr; 964 break; 965 966 // CHECK: Are we using "%n"? Issue a warning. 967 case 'n': { 968 ++numConversions; 969 CurrentState = state_OrdChr; 970 SourceLocation Loc = getLocationOfStringLiteralByte(FExpr, 971 LastConversionIdx); 972 973 Diag(Loc, diag::warn_printf_write_back)<<OrigFormatExpr->getSourceRange(); 974 break; 975 } 976 977 // Handle "%@" 978 case '@': 979 // %@ is allowed in ObjC format strings only. 980 if(ObjCFExpr != NULL) 981 CurrentState = state_OrdChr; 982 else { 983 // Issue a warning: invalid format conversion. 984 SourceLocation Loc = 985 getLocationOfStringLiteralByte(FExpr, LastConversionIdx); 986 987 Diag(Loc, diag::warn_printf_invalid_conversion) 988 << std::string(Str+LastConversionIdx, 989 Str+std::min(LastConversionIdx+2, StrLen)) 990 << OrigFormatExpr->getSourceRange(); 991 } 992 ++numConversions; 993 break; 994 995 // Handle "%%" 996 case '%': 997 // Sanity check: Was the first "%" character the previous one? 998 // If not, we will assume that we have a malformed format 999 // conversion, and that the current "%" character is the start 1000 // of a new conversion. 1001 if (StrIdx - LastConversionIdx == 1) 1002 CurrentState = state_OrdChr; 1003 else { 1004 // Issue a warning: invalid format conversion. 1005 SourceLocation Loc = 1006 getLocationOfStringLiteralByte(FExpr, LastConversionIdx); 1007 1008 Diag(Loc, diag::warn_printf_invalid_conversion) 1009 << std::string(Str+LastConversionIdx, Str+StrIdx) 1010 << OrigFormatExpr->getSourceRange(); 1011 1012 // This conversion is broken. Advance to the next format 1013 // conversion. 1014 LastConversionIdx = StrIdx; 1015 ++numConversions; 1016 } 1017 break; 1018 1019 default: 1020 // This case catches all other characters: flags, widths, etc. 1021 // We should eventually process those as well. 1022 break; 1023 } 1024 } 1025 1026 if (CurrentState == state_Conversion) { 1027 // Issue a warning: invalid format conversion. 1028 SourceLocation Loc = 1029 getLocationOfStringLiteralByte(FExpr, LastConversionIdx); 1030 1031 Diag(Loc, diag::warn_printf_invalid_conversion) 1032 << std::string(Str+LastConversionIdx, 1033 Str+std::min(LastConversionIdx+2, StrLen)) 1034 << OrigFormatExpr->getSourceRange(); 1035 return; 1036 } 1037 1038 if (!HasVAListArg) { 1039 // CHECK: Does the number of format conversions exceed the number 1040 // of data arguments? 1041 if (numConversions > numDataArgs) { 1042 SourceLocation Loc = 1043 getLocationOfStringLiteralByte(FExpr, LastConversionIdx); 1044 1045 Diag(Loc, diag::warn_printf_insufficient_data_args) 1046 << OrigFormatExpr->getSourceRange(); 1047 } 1048 // CHECK: Does the number of data arguments exceed the number of 1049 // format conversions in the format string? 1050 else if (numConversions < numDataArgs) 1051 Diag(TheCall->getArg(format_idx+numConversions+1)->getLocStart(), 1052 diag::warn_printf_too_many_data_args) 1053 << OrigFormatExpr->getSourceRange(); 1054 } 1055} 1056 1057//===--- CHECK: Return Address of Stack Variable --------------------------===// 1058 1059static DeclRefExpr* EvalVal(Expr *E); 1060static DeclRefExpr* EvalAddr(Expr* E); 1061 1062/// CheckReturnStackAddr - Check if a return statement returns the address 1063/// of a stack variable. 1064void 1065Sema::CheckReturnStackAddr(Expr *RetValExp, QualType lhsType, 1066 SourceLocation ReturnLoc) { 1067 1068 // Perform checking for returned stack addresses. 1069 if (lhsType->isPointerType() || lhsType->isBlockPointerType()) { 1070 if (DeclRefExpr *DR = EvalAddr(RetValExp)) 1071 Diag(DR->getLocStart(), diag::warn_ret_stack_addr) 1072 << DR->getDecl()->getDeclName() << RetValExp->getSourceRange(); 1073 1074 // Skip over implicit cast expressions when checking for block expressions. 1075 if (ImplicitCastExpr *IcExpr = 1076 dyn_cast_or_null<ImplicitCastExpr>(RetValExp)) 1077 RetValExp = IcExpr->getSubExpr(); 1078 1079 if (BlockExpr *C = dyn_cast_or_null<BlockExpr>(RetValExp)) 1080 if (C->hasBlockDeclRefExprs()) 1081 Diag(C->getLocStart(), diag::err_ret_local_block) 1082 << C->getSourceRange(); 1083 } 1084 // Perform checking for stack values returned by reference. 1085 else if (lhsType->isReferenceType()) { 1086 // Check for a reference to the stack 1087 if (DeclRefExpr *DR = EvalVal(RetValExp)) 1088 Diag(DR->getLocStart(), diag::warn_ret_stack_ref) 1089 << DR->getDecl()->getDeclName() << RetValExp->getSourceRange(); 1090 } 1091} 1092 1093/// EvalAddr - EvalAddr and EvalVal are mutually recursive functions that 1094/// check if the expression in a return statement evaluates to an address 1095/// to a location on the stack. The recursion is used to traverse the 1096/// AST of the return expression, with recursion backtracking when we 1097/// encounter a subexpression that (1) clearly does not lead to the address 1098/// of a stack variable or (2) is something we cannot determine leads to 1099/// the address of a stack variable based on such local checking. 1100/// 1101/// EvalAddr processes expressions that are pointers that are used as 1102/// references (and not L-values). EvalVal handles all other values. 1103/// At the base case of the recursion is a check for a DeclRefExpr* in 1104/// the refers to a stack variable. 1105/// 1106/// This implementation handles: 1107/// 1108/// * pointer-to-pointer casts 1109/// * implicit conversions from array references to pointers 1110/// * taking the address of fields 1111/// * arbitrary interplay between "&" and "*" operators 1112/// * pointer arithmetic from an address of a stack variable 1113/// * taking the address of an array element where the array is on the stack 1114static DeclRefExpr* EvalAddr(Expr *E) { 1115 // We should only be called for evaluating pointer expressions. 1116 assert((E->getType()->isPointerType() || 1117 E->getType()->isBlockPointerType() || 1118 E->getType()->isObjCQualifiedIdType()) && 1119 "EvalAddr only works on pointers"); 1120 1121 // Our "symbolic interpreter" is just a dispatch off the currently 1122 // viewed AST node. We then recursively traverse the AST by calling 1123 // EvalAddr and EvalVal appropriately. 1124 switch (E->getStmtClass()) { 1125 case Stmt::ParenExprClass: 1126 // Ignore parentheses. 1127 return EvalAddr(cast<ParenExpr>(E)->getSubExpr()); 1128 1129 case Stmt::UnaryOperatorClass: { 1130 // The only unary operator that make sense to handle here 1131 // is AddrOf. All others don't make sense as pointers. 1132 UnaryOperator *U = cast<UnaryOperator>(E); 1133 1134 if (U->getOpcode() == UnaryOperator::AddrOf) 1135 return EvalVal(U->getSubExpr()); 1136 else 1137 return NULL; 1138 } 1139 1140 case Stmt::BinaryOperatorClass: { 1141 // Handle pointer arithmetic. All other binary operators are not valid 1142 // in this context. 1143 BinaryOperator *B = cast<BinaryOperator>(E); 1144 BinaryOperator::Opcode op = B->getOpcode(); 1145 1146 if (op != BinaryOperator::Add && op != BinaryOperator::Sub) 1147 return NULL; 1148 1149 Expr *Base = B->getLHS(); 1150 1151 // Determine which argument is the real pointer base. It could be 1152 // the RHS argument instead of the LHS. 1153 if (!Base->getType()->isPointerType()) Base = B->getRHS(); 1154 1155 assert (Base->getType()->isPointerType()); 1156 return EvalAddr(Base); 1157 } 1158 1159 // For conditional operators we need to see if either the LHS or RHS are 1160 // valid DeclRefExpr*s. If one of them is valid, we return it. 1161 case Stmt::ConditionalOperatorClass: { 1162 ConditionalOperator *C = cast<ConditionalOperator>(E); 1163 1164 // Handle the GNU extension for missing LHS. 1165 if (Expr *lhsExpr = C->getLHS()) 1166 if (DeclRefExpr* LHS = EvalAddr(lhsExpr)) 1167 return LHS; 1168 1169 return EvalAddr(C->getRHS()); 1170 } 1171 1172 // For casts, we need to handle conversions from arrays to 1173 // pointer values, and pointer-to-pointer conversions. 1174 case Stmt::ImplicitCastExprClass: 1175 case Stmt::CStyleCastExprClass: 1176 case Stmt::CXXFunctionalCastExprClass: { 1177 Expr* SubExpr = cast<CastExpr>(E)->getSubExpr(); 1178 QualType T = SubExpr->getType(); 1179 1180 if (SubExpr->getType()->isPointerType() || 1181 SubExpr->getType()->isBlockPointerType() || 1182 SubExpr->getType()->isObjCQualifiedIdType()) 1183 return EvalAddr(SubExpr); 1184 else if (T->isArrayType()) 1185 return EvalVal(SubExpr); 1186 else 1187 return 0; 1188 } 1189 1190 // C++ casts. For dynamic casts, static casts, and const casts, we 1191 // are always converting from a pointer-to-pointer, so we just blow 1192 // through the cast. In the case the dynamic cast doesn't fail (and 1193 // return NULL), we take the conservative route and report cases 1194 // where we return the address of a stack variable. For Reinterpre 1195 // FIXME: The comment about is wrong; we're not always converting 1196 // from pointer to pointer. I'm guessing that this code should also 1197 // handle references to objects. 1198 case Stmt::CXXStaticCastExprClass: 1199 case Stmt::CXXDynamicCastExprClass: 1200 case Stmt::CXXConstCastExprClass: 1201 case Stmt::CXXReinterpretCastExprClass: { 1202 Expr *S = cast<CXXNamedCastExpr>(E)->getSubExpr(); 1203 if (S->getType()->isPointerType() || S->getType()->isBlockPointerType()) 1204 return EvalAddr(S); 1205 else 1206 return NULL; 1207 } 1208 1209 // Everything else: we simply don't reason about them. 1210 default: 1211 return NULL; 1212 } 1213} 1214 1215 1216/// EvalVal - This function is complements EvalAddr in the mutual recursion. 1217/// See the comments for EvalAddr for more details. 1218static DeclRefExpr* EvalVal(Expr *E) { 1219 1220 // We should only be called for evaluating non-pointer expressions, or 1221 // expressions with a pointer type that are not used as references but instead 1222 // are l-values (e.g., DeclRefExpr with a pointer type). 1223 1224 // Our "symbolic interpreter" is just a dispatch off the currently 1225 // viewed AST node. We then recursively traverse the AST by calling 1226 // EvalAddr and EvalVal appropriately. 1227 switch (E->getStmtClass()) { 1228 case Stmt::DeclRefExprClass: 1229 case Stmt::QualifiedDeclRefExprClass: { 1230 // DeclRefExpr: the base case. When we hit a DeclRefExpr we are looking 1231 // at code that refers to a variable's name. We check if it has local 1232 // storage within the function, and if so, return the expression. 1233 DeclRefExpr *DR = cast<DeclRefExpr>(E); 1234 1235 if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl())) 1236 if(V->hasLocalStorage() && !V->getType()->isReferenceType()) return DR; 1237 1238 return NULL; 1239 } 1240 1241 case Stmt::ParenExprClass: 1242 // Ignore parentheses. 1243 return EvalVal(cast<ParenExpr>(E)->getSubExpr()); 1244 1245 case Stmt::UnaryOperatorClass: { 1246 // The only unary operator that make sense to handle here 1247 // is Deref. All others don't resolve to a "name." This includes 1248 // handling all sorts of rvalues passed to a unary operator. 1249 UnaryOperator *U = cast<UnaryOperator>(E); 1250 1251 if (U->getOpcode() == UnaryOperator::Deref) 1252 return EvalAddr(U->getSubExpr()); 1253 1254 return NULL; 1255 } 1256 1257 case Stmt::ArraySubscriptExprClass: { 1258 // Array subscripts are potential references to data on the stack. We 1259 // retrieve the DeclRefExpr* for the array variable if it indeed 1260 // has local storage. 1261 return EvalAddr(cast<ArraySubscriptExpr>(E)->getBase()); 1262 } 1263 1264 case Stmt::ConditionalOperatorClass: { 1265 // For conditional operators we need to see if either the LHS or RHS are 1266 // non-NULL DeclRefExpr's. If one is non-NULL, we return it. 1267 ConditionalOperator *C = cast<ConditionalOperator>(E); 1268 1269 // Handle the GNU extension for missing LHS. 1270 if (Expr *lhsExpr = C->getLHS()) 1271 if (DeclRefExpr *LHS = EvalVal(lhsExpr)) 1272 return LHS; 1273 1274 return EvalVal(C->getRHS()); 1275 } 1276 1277 // Accesses to members are potential references to data on the stack. 1278 case Stmt::MemberExprClass: { 1279 MemberExpr *M = cast<MemberExpr>(E); 1280 1281 // Check for indirect access. We only want direct field accesses. 1282 if (!M->isArrow()) 1283 return EvalVal(M->getBase()); 1284 else 1285 return NULL; 1286 } 1287 1288 // Everything else: we simply don't reason about them. 1289 default: 1290 return NULL; 1291 } 1292} 1293 1294//===--- CHECK: Floating-Point comparisons (-Wfloat-equal) ---------------===// 1295 1296/// Check for comparisons of floating point operands using != and ==. 1297/// Issue a warning if these are no self-comparisons, as they are not likely 1298/// to do what the programmer intended. 1299void Sema::CheckFloatComparison(SourceLocation loc, Expr* lex, Expr *rex) { 1300 bool EmitWarning = true; 1301 1302 Expr* LeftExprSansParen = lex->IgnoreParens(); 1303 Expr* RightExprSansParen = rex->IgnoreParens(); 1304 1305 // Special case: check for x == x (which is OK). 1306 // Do not emit warnings for such cases. 1307 if (DeclRefExpr* DRL = dyn_cast<DeclRefExpr>(LeftExprSansParen)) 1308 if (DeclRefExpr* DRR = dyn_cast<DeclRefExpr>(RightExprSansParen)) 1309 if (DRL->getDecl() == DRR->getDecl()) 1310 EmitWarning = false; 1311 1312 1313 // Special case: check for comparisons against literals that can be exactly 1314 // represented by APFloat. In such cases, do not emit a warning. This 1315 // is a heuristic: often comparison against such literals are used to 1316 // detect if a value in a variable has not changed. This clearly can 1317 // lead to false negatives. 1318 if (EmitWarning) { 1319 if (FloatingLiteral* FLL = dyn_cast<FloatingLiteral>(LeftExprSansParen)) { 1320 if (FLL->isExact()) 1321 EmitWarning = false; 1322 } 1323 else 1324 if (FloatingLiteral* FLR = dyn_cast<FloatingLiteral>(RightExprSansParen)){ 1325 if (FLR->isExact()) 1326 EmitWarning = false; 1327 } 1328 } 1329 1330 // Check for comparisons with builtin types. 1331 if (EmitWarning) 1332 if (CallExpr* CL = dyn_cast<CallExpr>(LeftExprSansParen)) 1333 if (CL->isBuiltinCall(Context)) 1334 EmitWarning = false; 1335 1336 if (EmitWarning) 1337 if (CallExpr* CR = dyn_cast<CallExpr>(RightExprSansParen)) 1338 if (CR->isBuiltinCall(Context)) 1339 EmitWarning = false; 1340 1341 // Emit the diagnostic. 1342 if (EmitWarning) 1343 Diag(loc, diag::warn_floatingpoint_eq) 1344 << lex->getSourceRange() << rex->getSourceRange(); 1345} 1346