SemaChecking.cpp revision e7ac0a94f1dee3fae9292eb8372962b6d70b3e0d
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(); 295 296 297 // Get the decl for the concrete builtin from this, we can tell what the 298 // concrete integer type we should convert to is. 299 unsigned NewBuiltinID = BuiltinIndices[BuiltinIndex][SizeIndex]; 300 const char *NewBuiltinName = Context.BuiltinInfo.GetName(NewBuiltinID); 301 IdentifierInfo *NewBuiltinII = PP.getIdentifierInfo(NewBuiltinName); 302 FunctionDecl *NewBuiltinDecl = 303 cast<FunctionDecl>(LazilyCreateBuiltin(NewBuiltinII, NewBuiltinID, 304 TUScope, false, DRE->getLocStart())); 305 const FunctionProtoType *BuiltinFT = 306 NewBuiltinDecl->getType()->getAsFunctionProtoType(); 307 ValType = BuiltinFT->getArgType(0)->getAsPointerType()->getPointeeType(); 308 309 // If the first type needs to be converted (e.g. void** -> int*), do it now. 310 if (BuiltinFT->getArgType(0) != FirstArg->getType()) { 311 ImpCastExprToType(FirstArg, BuiltinFT->getArgType(0), false); 312 TheCall->setArg(0, FirstArg); 313 } 314 315 // Next, walk the valid ones promoting to the right type. 316 for (unsigned i = 0; i != NumFixed; ++i) { 317 Expr *Arg = TheCall->getArg(i+1); 318 319 // If the argument is an implicit cast, then there was a promotion due to 320 // "...", just remove it now. 321 if (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Arg)) { 322 Arg = ICE->getSubExpr(); 323 ICE->setSubExpr(0); 324 ICE->Destroy(Context); 325 TheCall->setArg(i+1, Arg); 326 } 327 328 // GCC does an implicit conversion to the pointer or integer ValType. This 329 // can fail in some cases (1i -> int**), check for this error case now. 330 if (CheckCastTypes(Arg->getSourceRange(), ValType, Arg)) 331 return true; 332 333 // Okay, we have something that *can* be converted to the right type. Check 334 // to see if there is a potentially weird extension going on here. This can 335 // happen when you do an atomic operation on something like an char* and 336 // pass in 42. The 42 gets converted to char. This is even more strange 337 // for things like 45.123 -> char, etc. 338 // FIXME: Do this check. 339 ImpCastExprToType(Arg, ValType, false); 340 TheCall->setArg(i+1, Arg); 341 } 342 343 // Switch the DeclRefExpr to refer to the new decl. 344 DRE->setDecl(NewBuiltinDecl); 345 DRE->setType(NewBuiltinDecl->getType()); 346 347 // Set the callee in the CallExpr. 348 // FIXME: This leaks the original parens and implicit casts. 349 Expr *PromotedCall = DRE; 350 UsualUnaryConversions(PromotedCall); 351 TheCall->setCallee(PromotedCall); 352 353 354 // Change the result type of the call to match the result type of the decl. 355 TheCall->setType(NewBuiltinDecl->getResultType()); 356 return false; 357} 358 359 360/// CheckObjCString - Checks that the argument to the builtin 361/// CFString constructor is correct 362/// FIXME: GCC currently emits the following warning: 363/// "warning: input conversion stopped due to an input byte that does not 364/// belong to the input codeset UTF-8" 365/// Note: It might also make sense to do the UTF-16 conversion here (would 366/// simplify the backend). 367bool Sema::CheckObjCString(Expr *Arg) { 368 Arg = Arg->IgnoreParenCasts(); 369 StringLiteral *Literal = dyn_cast<StringLiteral>(Arg); 370 371 if (!Literal || Literal->isWide()) { 372 Diag(Arg->getLocStart(), diag::err_cfstring_literal_not_string_constant) 373 << Arg->getSourceRange(); 374 return true; 375 } 376 377 const char *Data = Literal->getStrData(); 378 unsigned Length = Literal->getByteLength(); 379 380 for (unsigned i = 0; i < Length; ++i) { 381 if (!Data[i]) { 382 Diag(getLocationOfStringLiteralByte(Literal, i), 383 diag::warn_cfstring_literal_contains_nul_character) 384 << Arg->getSourceRange(); 385 break; 386 } 387 } 388 389 return false; 390} 391 392/// SemaBuiltinVAStart - Check the arguments to __builtin_va_start for validity. 393/// Emit an error and return true on failure, return false on success. 394bool Sema::SemaBuiltinVAStart(CallExpr *TheCall) { 395 Expr *Fn = TheCall->getCallee(); 396 if (TheCall->getNumArgs() > 2) { 397 Diag(TheCall->getArg(2)->getLocStart(), 398 diag::err_typecheck_call_too_many_args) 399 << 0 /*function call*/ << Fn->getSourceRange() 400 << SourceRange(TheCall->getArg(2)->getLocStart(), 401 (*(TheCall->arg_end()-1))->getLocEnd()); 402 return true; 403 } 404 405 if (TheCall->getNumArgs() < 2) { 406 return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args) 407 << 0 /*function call*/; 408 } 409 410 // Determine whether the current function is variadic or not. 411 bool isVariadic; 412 if (CurBlock) 413 isVariadic = CurBlock->isVariadic; 414 else if (getCurFunctionDecl()) { 415 if (FunctionProtoType* FTP = 416 dyn_cast<FunctionProtoType>(getCurFunctionDecl()->getType())) 417 isVariadic = FTP->isVariadic(); 418 else 419 isVariadic = false; 420 } else { 421 isVariadic = getCurMethodDecl()->isVariadic(); 422 } 423 424 if (!isVariadic) { 425 Diag(Fn->getLocStart(), diag::err_va_start_used_in_non_variadic_function); 426 return true; 427 } 428 429 // Verify that the second argument to the builtin is the last argument of the 430 // current function or method. 431 bool SecondArgIsLastNamedArgument = false; 432 const Expr *Arg = TheCall->getArg(1)->IgnoreParenCasts(); 433 434 if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Arg)) { 435 if (const ParmVarDecl *PV = dyn_cast<ParmVarDecl>(DR->getDecl())) { 436 // FIXME: This isn't correct for methods (results in bogus warning). 437 // Get the last formal in the current function. 438 const ParmVarDecl *LastArg; 439 if (CurBlock) 440 LastArg = *(CurBlock->TheDecl->param_end()-1); 441 else if (FunctionDecl *FD = getCurFunctionDecl()) 442 LastArg = *(FD->param_end()-1); 443 else 444 LastArg = *(getCurMethodDecl()->param_end()-1); 445 SecondArgIsLastNamedArgument = PV == LastArg; 446 } 447 } 448 449 if (!SecondArgIsLastNamedArgument) 450 Diag(TheCall->getArg(1)->getLocStart(), 451 diag::warn_second_parameter_of_va_start_not_last_named_argument); 452 return false; 453} 454 455/// SemaBuiltinUnorderedCompare - Handle functions like __builtin_isgreater and 456/// friends. This is declared to take (...), so we have to check everything. 457bool Sema::SemaBuiltinUnorderedCompare(CallExpr *TheCall) { 458 if (TheCall->getNumArgs() < 2) 459 return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args) 460 << 0 /*function call*/; 461 if (TheCall->getNumArgs() > 2) 462 return Diag(TheCall->getArg(2)->getLocStart(), 463 diag::err_typecheck_call_too_many_args) 464 << 0 /*function call*/ 465 << SourceRange(TheCall->getArg(2)->getLocStart(), 466 (*(TheCall->arg_end()-1))->getLocEnd()); 467 468 Expr *OrigArg0 = TheCall->getArg(0); 469 Expr *OrigArg1 = TheCall->getArg(1); 470 471 // Do standard promotions between the two arguments, returning their common 472 // type. 473 QualType Res = UsualArithmeticConversions(OrigArg0, OrigArg1, false); 474 475 // Make sure any conversions are pushed back into the call; this is 476 // type safe since unordered compare builtins are declared as "_Bool 477 // foo(...)". 478 TheCall->setArg(0, OrigArg0); 479 TheCall->setArg(1, OrigArg1); 480 481 // If the common type isn't a real floating type, then the arguments were 482 // invalid for this operation. 483 if (!Res->isRealFloatingType()) 484 return Diag(OrigArg0->getLocStart(), 485 diag::err_typecheck_call_invalid_ordered_compare) 486 << OrigArg0->getType() << OrigArg1->getType() 487 << SourceRange(OrigArg0->getLocStart(), OrigArg1->getLocEnd()); 488 489 return false; 490} 491 492bool Sema::SemaBuiltinStackAddress(CallExpr *TheCall) { 493 // The signature for these builtins is exact; the only thing we need 494 // to check is that the argument is a constant. 495 SourceLocation Loc; 496 if (!TheCall->getArg(0)->isIntegerConstantExpr(Context, &Loc)) 497 return Diag(Loc, diag::err_stack_const_level) << TheCall->getSourceRange(); 498 499 return false; 500} 501 502/// SemaBuiltinShuffleVector - Handle __builtin_shufflevector. 503// This is declared to take (...), so we have to check everything. 504Action::OwningExprResult Sema::SemaBuiltinShuffleVector(CallExpr *TheCall) { 505 if (TheCall->getNumArgs() < 3) 506 return ExprError(Diag(TheCall->getLocEnd(), 507 diag::err_typecheck_call_too_few_args) 508 << 0 /*function call*/ << TheCall->getSourceRange()); 509 510 QualType FAType = TheCall->getArg(0)->getType(); 511 QualType SAType = TheCall->getArg(1)->getType(); 512 513 if (!FAType->isVectorType() || !SAType->isVectorType()) { 514 Diag(TheCall->getLocStart(), diag::err_shufflevector_non_vector) 515 << SourceRange(TheCall->getArg(0)->getLocStart(), 516 TheCall->getArg(1)->getLocEnd()); 517 return ExprError(); 518 } 519 520 if (Context.getCanonicalType(FAType).getUnqualifiedType() != 521 Context.getCanonicalType(SAType).getUnqualifiedType()) { 522 Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector) 523 << SourceRange(TheCall->getArg(0)->getLocStart(), 524 TheCall->getArg(1)->getLocEnd()); 525 return ExprError(); 526 } 527 528 unsigned numElements = FAType->getAsVectorType()->getNumElements(); 529 if (TheCall->getNumArgs() != numElements+2) { 530 if (TheCall->getNumArgs() < numElements+2) 531 return ExprError(Diag(TheCall->getLocEnd(), 532 diag::err_typecheck_call_too_few_args) 533 << 0 /*function call*/ << TheCall->getSourceRange()); 534 return ExprError(Diag(TheCall->getLocEnd(), 535 diag::err_typecheck_call_too_many_args) 536 << 0 /*function call*/ << TheCall->getSourceRange()); 537 } 538 539 for (unsigned i = 2; i < TheCall->getNumArgs(); i++) { 540 llvm::APSInt Result(32); 541 if (!TheCall->getArg(i)->isIntegerConstantExpr(Result, Context)) 542 return ExprError(Diag(TheCall->getLocStart(), 543 diag::err_shufflevector_nonconstant_argument) 544 << TheCall->getArg(i)->getSourceRange()); 545 546 if (Result.getActiveBits() > 64 || Result.getZExtValue() >= numElements*2) 547 return ExprError(Diag(TheCall->getLocStart(), 548 diag::err_shufflevector_argument_too_large) 549 << TheCall->getArg(i)->getSourceRange()); 550 } 551 552 llvm::SmallVector<Expr*, 32> exprs; 553 554 for (unsigned i = 0, e = TheCall->getNumArgs(); i != e; i++) { 555 exprs.push_back(TheCall->getArg(i)); 556 TheCall->setArg(i, 0); 557 } 558 559 return Owned(new (Context) ShuffleVectorExpr(exprs.begin(), numElements+2, 560 FAType, 561 TheCall->getCallee()->getLocStart(), 562 TheCall->getRParenLoc())); 563} 564 565/// SemaBuiltinPrefetch - Handle __builtin_prefetch. 566// This is declared to take (const void*, ...) and can take two 567// optional constant int args. 568bool Sema::SemaBuiltinPrefetch(CallExpr *TheCall) { 569 unsigned NumArgs = TheCall->getNumArgs(); 570 571 if (NumArgs > 3) 572 return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_many_args) 573 << 0 /*function call*/ << TheCall->getSourceRange(); 574 575 // Argument 0 is checked for us and the remaining arguments must be 576 // constant integers. 577 for (unsigned i = 1; i != NumArgs; ++i) { 578 Expr *Arg = TheCall->getArg(i); 579 QualType RWType = Arg->getType(); 580 581 const BuiltinType *BT = RWType->getAsBuiltinType(); 582 llvm::APSInt Result; 583 if (!BT || BT->getKind() != BuiltinType::Int || 584 !Arg->isIntegerConstantExpr(Result, Context)) 585 return Diag(TheCall->getLocStart(), diag::err_prefetch_invalid_argument) 586 << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); 587 588 // FIXME: gcc issues a warning and rewrites these to 0. These 589 // seems especially odd for the third argument since the default 590 // is 3. 591 if (i == 1) { 592 if (Result.getSExtValue() < 0 || Result.getSExtValue() > 1) 593 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 594 << "0" << "1" << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); 595 } else { 596 if (Result.getSExtValue() < 0 || Result.getSExtValue() > 3) 597 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 598 << "0" << "3" << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); 599 } 600 } 601 602 return false; 603} 604 605/// SemaBuiltinObjectSize - Handle __builtin_object_size(void *ptr, 606/// int type). This simply type checks that type is one of the defined 607/// constants (0-3). 608bool Sema::SemaBuiltinObjectSize(CallExpr *TheCall) { 609 Expr *Arg = TheCall->getArg(1); 610 QualType ArgType = Arg->getType(); 611 const BuiltinType *BT = ArgType->getAsBuiltinType(); 612 llvm::APSInt Result(32); 613 if (!BT || BT->getKind() != BuiltinType::Int || 614 !Arg->isIntegerConstantExpr(Result, Context)) { 615 return Diag(TheCall->getLocStart(), diag::err_object_size_invalid_argument) 616 << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); 617 } 618 619 if (Result.getSExtValue() < 0 || Result.getSExtValue() > 3) { 620 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 621 << "0" << "3" << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); 622 } 623 624 return false; 625} 626 627/// SemaBuiltinLongjmp - Handle __builtin_longjmp(void *env[5], int val). 628/// This checks that val is a constant 1. 629bool Sema::SemaBuiltinLongjmp(CallExpr *TheCall) { 630 Expr *Arg = TheCall->getArg(1); 631 llvm::APSInt Result(32); 632 if (!Arg->isIntegerConstantExpr(Result, Context) || Result != 1) 633 return Diag(TheCall->getLocStart(), diag::err_builtin_longjmp_invalid_val) 634 << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); 635 636 return false; 637} 638 639// Handle i > 1 ? "x" : "y", recursivelly 640bool Sema::SemaCheckStringLiteral(const Expr *E, const CallExpr *TheCall, 641 bool HasVAListArg, 642 unsigned format_idx, unsigned firstDataArg) { 643 644 switch (E->getStmtClass()) { 645 case Stmt::ConditionalOperatorClass: { 646 const ConditionalOperator *C = cast<ConditionalOperator>(E); 647 return SemaCheckStringLiteral(C->getLHS(), TheCall, 648 HasVAListArg, format_idx, firstDataArg) 649 && SemaCheckStringLiteral(C->getRHS(), TheCall, 650 HasVAListArg, format_idx, firstDataArg); 651 } 652 653 case Stmt::ImplicitCastExprClass: { 654 const ImplicitCastExpr *Expr = cast<ImplicitCastExpr>(E); 655 return SemaCheckStringLiteral(Expr->getSubExpr(), TheCall, HasVAListArg, 656 format_idx, firstDataArg); 657 } 658 659 case Stmt::ParenExprClass: { 660 const ParenExpr *Expr = cast<ParenExpr>(E); 661 return SemaCheckStringLiteral(Expr->getSubExpr(), TheCall, HasVAListArg, 662 format_idx, firstDataArg); 663 } 664 665 case Stmt::DeclRefExprClass: { 666 const DeclRefExpr *DR = cast<DeclRefExpr>(E); 667 668 // As an exception, do not flag errors for variables binding to 669 // const string literals. 670 if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) { 671 bool isConstant = false; 672 QualType T = DR->getType(); 673 674 if (const ArrayType *AT = Context.getAsArrayType(T)) { 675 isConstant = AT->getElementType().isConstant(Context); 676 } 677 else if (const PointerType *PT = T->getAsPointerType()) { 678 isConstant = T.isConstant(Context) && 679 PT->getPointeeType().isConstant(Context); 680 } 681 682 if (isConstant) { 683 const VarDecl *Def = 0; 684 if (const Expr *Init = VD->getDefinition(Def)) 685 return SemaCheckStringLiteral(Init, TheCall, 686 HasVAListArg, format_idx, firstDataArg); 687 } 688 } 689 690 return false; 691 } 692 693 case Stmt::ObjCStringLiteralClass: 694 case Stmt::StringLiteralClass: { 695 const StringLiteral *StrE = NULL; 696 697 if (const ObjCStringLiteral *ObjCFExpr = dyn_cast<ObjCStringLiteral>(E)) 698 StrE = ObjCFExpr->getString(); 699 else 700 StrE = cast<StringLiteral>(E); 701 702 if (StrE) { 703 CheckPrintfString(StrE, E, TheCall, HasVAListArg, format_idx, 704 firstDataArg); 705 return true; 706 } 707 708 return false; 709 } 710 711 default: 712 return false; 713 } 714} 715 716 717/// CheckPrintfArguments - Check calls to printf (and similar functions) for 718/// correct use of format strings. 719/// 720/// HasVAListArg - A predicate indicating whether the printf-like 721/// function is passed an explicit va_arg argument (e.g., vprintf) 722/// 723/// format_idx - The index into Args for the format string. 724/// 725/// Improper format strings to functions in the printf family can be 726/// the source of bizarre bugs and very serious security holes. A 727/// good source of information is available in the following paper 728/// (which includes additional references): 729/// 730/// FormatGuard: Automatic Protection From printf Format String 731/// Vulnerabilities, Proceedings of the 10th USENIX Security Symposium, 2001. 732/// 733/// Functionality implemented: 734/// 735/// We can statically check the following properties for string 736/// literal format strings for non v.*printf functions (where the 737/// arguments are passed directly): 738// 739/// (1) Are the number of format conversions equal to the number of 740/// data arguments? 741/// 742/// (2) Does each format conversion correctly match the type of the 743/// corresponding data argument? (TODO) 744/// 745/// Moreover, for all printf functions we can: 746/// 747/// (3) Check for a missing format string (when not caught by type checking). 748/// 749/// (4) Check for no-operation flags; e.g. using "#" with format 750/// conversion 'c' (TODO) 751/// 752/// (5) Check the use of '%n', a major source of security holes. 753/// 754/// (6) Check for malformed format conversions that don't specify anything. 755/// 756/// (7) Check for empty format strings. e.g: printf(""); 757/// 758/// (8) Check that the format string is a wide literal. 759/// 760/// (9) Also check the arguments of functions with the __format__ attribute. 761/// (TODO). 762/// 763/// All of these checks can be done by parsing the format string. 764/// 765/// For now, we ONLY do (1), (3), (5), (6), (7), and (8). 766void 767Sema::CheckPrintfArguments(const CallExpr *TheCall, bool HasVAListArg, 768 unsigned format_idx, unsigned firstDataArg) { 769 const Expr *Fn = TheCall->getCallee(); 770 771 // CHECK: printf-like function is called with no format string. 772 if (format_idx >= TheCall->getNumArgs()) { 773 Diag(TheCall->getRParenLoc(), diag::warn_printf_missing_format_string) 774 << Fn->getSourceRange(); 775 return; 776 } 777 778 const Expr *OrigFormatExpr = TheCall->getArg(format_idx)->IgnoreParenCasts(); 779 780 // CHECK: format string is not a string literal. 781 // 782 // Dynamically generated format strings are difficult to 783 // automatically vet at compile time. Requiring that format strings 784 // are string literals: (1) permits the checking of format strings by 785 // the compiler and thereby (2) can practically remove the source of 786 // many format string exploits. 787 788 // Format string can be either ObjC string (e.g. @"%d") or 789 // C string (e.g. "%d") 790 // ObjC string uses the same format specifiers as C string, so we can use 791 // the same format string checking logic for both ObjC and C strings. 792 if (SemaCheckStringLiteral(OrigFormatExpr, TheCall, HasVAListArg, format_idx, 793 firstDataArg)) 794 return; // Literal format string found, check done! 795 796 // For vprintf* functions (i.e., HasVAListArg==true), we add a 797 // special check to see if the format string is a function parameter 798 // of the function calling the printf function. If the function 799 // has an attribute indicating it is a printf-like function, then we 800 // should suppress warnings concerning non-literals being used in a call 801 // to a vprintf function. For example: 802 // 803 // void 804 // logmessage(char const *fmt __attribute__ (format (printf, 1, 2)), ...) { 805 // va_list ap; 806 // va_start(ap, fmt); 807 // vprintf(fmt, ap); // Do NOT emit a warning about "fmt". 808 // ... 809 // 810 // 811 // FIXME: We don't have full attribute support yet, so just check to see 812 // if the argument is a DeclRefExpr that references a parameter. We'll 813 // add proper support for checking the attribute later. 814 if (HasVAListArg) 815 if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(OrigFormatExpr)) 816 if (isa<ParmVarDecl>(DR->getDecl())) 817 return; 818 819 // If there are no arguments specified, warn with -Wformat-security, otherwise 820 // warn only with -Wformat-nonliteral. 821 if (TheCall->getNumArgs() == format_idx+1) 822 Diag(TheCall->getArg(format_idx)->getLocStart(), 823 diag::warn_printf_nonliteral_noargs) 824 << OrigFormatExpr->getSourceRange(); 825 else 826 Diag(TheCall->getArg(format_idx)->getLocStart(), 827 diag::warn_printf_nonliteral) 828 << OrigFormatExpr->getSourceRange(); 829} 830 831void Sema::CheckPrintfString(const StringLiteral *FExpr, 832 const Expr *OrigFormatExpr, 833 const CallExpr *TheCall, bool HasVAListArg, 834 unsigned format_idx, unsigned firstDataArg) { 835 836 const ObjCStringLiteral *ObjCFExpr = 837 dyn_cast<ObjCStringLiteral>(OrigFormatExpr); 838 839 // CHECK: is the format string a wide literal? 840 if (FExpr->isWide()) { 841 Diag(FExpr->getLocStart(), 842 diag::warn_printf_format_string_is_wide_literal) 843 << OrigFormatExpr->getSourceRange(); 844 return; 845 } 846 847 // Str - The format string. NOTE: this is NOT null-terminated! 848 const char *Str = FExpr->getStrData(); 849 850 // CHECK: empty format string? 851 unsigned StrLen = FExpr->getByteLength(); 852 853 if (StrLen == 0) { 854 Diag(FExpr->getLocStart(), diag::warn_printf_empty_format_string) 855 << OrigFormatExpr->getSourceRange(); 856 return; 857 } 858 859 // We process the format string using a binary state machine. The 860 // current state is stored in CurrentState. 861 enum { 862 state_OrdChr, 863 state_Conversion 864 } CurrentState = state_OrdChr; 865 866 // numConversions - The number of conversions seen so far. This is 867 // incremented as we traverse the format string. 868 unsigned numConversions = 0; 869 870 // numDataArgs - The number of data arguments after the format 871 // string. This can only be determined for non vprintf-like 872 // functions. For those functions, this value is 1 (the sole 873 // va_arg argument). 874 unsigned numDataArgs = TheCall->getNumArgs()-firstDataArg; 875 876 // Inspect the format string. 877 unsigned StrIdx = 0; 878 879 // LastConversionIdx - Index within the format string where we last saw 880 // a '%' character that starts a new format conversion. 881 unsigned LastConversionIdx = 0; 882 883 for (; StrIdx < StrLen; ++StrIdx) { 884 885 // Is the number of detected conversion conversions greater than 886 // the number of matching data arguments? If so, stop. 887 if (!HasVAListArg && numConversions > numDataArgs) break; 888 889 // Handle "\0" 890 if (Str[StrIdx] == '\0') { 891 // The string returned by getStrData() is not null-terminated, 892 // so the presence of a null character is likely an error. 893 Diag(getLocationOfStringLiteralByte(FExpr, StrIdx), 894 diag::warn_printf_format_string_contains_null_char) 895 << OrigFormatExpr->getSourceRange(); 896 return; 897 } 898 899 // Ordinary characters (not processing a format conversion). 900 if (CurrentState == state_OrdChr) { 901 if (Str[StrIdx] == '%') { 902 CurrentState = state_Conversion; 903 LastConversionIdx = StrIdx; 904 } 905 continue; 906 } 907 908 // Seen '%'. Now processing a format conversion. 909 switch (Str[StrIdx]) { 910 // Handle dynamic precision or width specifier. 911 case '*': { 912 ++numConversions; 913 914 if (!HasVAListArg && numConversions > numDataArgs) { 915 SourceLocation Loc = getLocationOfStringLiteralByte(FExpr, StrIdx); 916 917 if (Str[StrIdx-1] == '.') 918 Diag(Loc, diag::warn_printf_asterisk_precision_missing_arg) 919 << OrigFormatExpr->getSourceRange(); 920 else 921 Diag(Loc, diag::warn_printf_asterisk_width_missing_arg) 922 << OrigFormatExpr->getSourceRange(); 923 924 // Don't do any more checking. We'll just emit spurious errors. 925 return; 926 } 927 928 // Perform type checking on width/precision specifier. 929 const Expr *E = TheCall->getArg(format_idx+numConversions); 930 if (const BuiltinType *BT = E->getType()->getAsBuiltinType()) 931 if (BT->getKind() == BuiltinType::Int) 932 break; 933 934 SourceLocation Loc = getLocationOfStringLiteralByte(FExpr, StrIdx); 935 936 if (Str[StrIdx-1] == '.') 937 Diag(Loc, diag::warn_printf_asterisk_precision_wrong_type) 938 << E->getType() << E->getSourceRange(); 939 else 940 Diag(Loc, diag::warn_printf_asterisk_width_wrong_type) 941 << E->getType() << E->getSourceRange(); 942 943 break; 944 } 945 946 // Characters which can terminate a format conversion 947 // (e.g. "%d"). Characters that specify length modifiers or 948 // other flags are handled by the default case below. 949 // 950 // FIXME: additional checks will go into the following cases. 951 case 'i': 952 case 'd': 953 case 'o': 954 case 'u': 955 case 'x': 956 case 'X': 957 case 'D': 958 case 'O': 959 case 'U': 960 case 'e': 961 case 'E': 962 case 'f': 963 case 'F': 964 case 'g': 965 case 'G': 966 case 'a': 967 case 'A': 968 case 'c': 969 case 'C': 970 case 'S': 971 case 's': 972 case 'p': 973 ++numConversions; 974 CurrentState = state_OrdChr; 975 break; 976 977 // CHECK: Are we using "%n"? Issue a warning. 978 case 'n': { 979 ++numConversions; 980 CurrentState = state_OrdChr; 981 SourceLocation Loc = getLocationOfStringLiteralByte(FExpr, 982 LastConversionIdx); 983 984 Diag(Loc, diag::warn_printf_write_back)<<OrigFormatExpr->getSourceRange(); 985 break; 986 } 987 988 // Handle "%@" 989 case '@': 990 // %@ is allowed in ObjC format strings only. 991 if(ObjCFExpr != NULL) 992 CurrentState = state_OrdChr; 993 else { 994 // Issue a warning: invalid format conversion. 995 SourceLocation Loc = 996 getLocationOfStringLiteralByte(FExpr, LastConversionIdx); 997 998 Diag(Loc, diag::warn_printf_invalid_conversion) 999 << std::string(Str+LastConversionIdx, 1000 Str+std::min(LastConversionIdx+2, StrLen)) 1001 << OrigFormatExpr->getSourceRange(); 1002 } 1003 ++numConversions; 1004 break; 1005 1006 // Handle "%%" 1007 case '%': 1008 // Sanity check: Was the first "%" character the previous one? 1009 // If not, we will assume that we have a malformed format 1010 // conversion, and that the current "%" character is the start 1011 // of a new conversion. 1012 if (StrIdx - LastConversionIdx == 1) 1013 CurrentState = state_OrdChr; 1014 else { 1015 // Issue a warning: invalid format conversion. 1016 SourceLocation Loc = 1017 getLocationOfStringLiteralByte(FExpr, LastConversionIdx); 1018 1019 Diag(Loc, diag::warn_printf_invalid_conversion) 1020 << std::string(Str+LastConversionIdx, Str+StrIdx) 1021 << OrigFormatExpr->getSourceRange(); 1022 1023 // This conversion is broken. Advance to the next format 1024 // conversion. 1025 LastConversionIdx = StrIdx; 1026 ++numConversions; 1027 } 1028 break; 1029 1030 default: 1031 // This case catches all other characters: flags, widths, etc. 1032 // We should eventually process those as well. 1033 break; 1034 } 1035 } 1036 1037 if (CurrentState == state_Conversion) { 1038 // Issue a warning: invalid format conversion. 1039 SourceLocation Loc = 1040 getLocationOfStringLiteralByte(FExpr, LastConversionIdx); 1041 1042 Diag(Loc, diag::warn_printf_invalid_conversion) 1043 << std::string(Str+LastConversionIdx, 1044 Str+std::min(LastConversionIdx+2, StrLen)) 1045 << OrigFormatExpr->getSourceRange(); 1046 return; 1047 } 1048 1049 if (!HasVAListArg) { 1050 // CHECK: Does the number of format conversions exceed the number 1051 // of data arguments? 1052 if (numConversions > numDataArgs) { 1053 SourceLocation Loc = 1054 getLocationOfStringLiteralByte(FExpr, LastConversionIdx); 1055 1056 Diag(Loc, diag::warn_printf_insufficient_data_args) 1057 << OrigFormatExpr->getSourceRange(); 1058 } 1059 // CHECK: Does the number of data arguments exceed the number of 1060 // format conversions in the format string? 1061 else if (numConversions < numDataArgs) 1062 Diag(TheCall->getArg(format_idx+numConversions+1)->getLocStart(), 1063 diag::warn_printf_too_many_data_args) 1064 << OrigFormatExpr->getSourceRange(); 1065 } 1066} 1067 1068//===--- CHECK: Return Address of Stack Variable --------------------------===// 1069 1070static DeclRefExpr* EvalVal(Expr *E); 1071static DeclRefExpr* EvalAddr(Expr* E); 1072 1073/// CheckReturnStackAddr - Check if a return statement returns the address 1074/// of a stack variable. 1075void 1076Sema::CheckReturnStackAddr(Expr *RetValExp, QualType lhsType, 1077 SourceLocation ReturnLoc) { 1078 1079 // Perform checking for returned stack addresses. 1080 if (lhsType->isPointerType() || lhsType->isBlockPointerType()) { 1081 if (DeclRefExpr *DR = EvalAddr(RetValExp)) 1082 Diag(DR->getLocStart(), diag::warn_ret_stack_addr) 1083 << DR->getDecl()->getDeclName() << RetValExp->getSourceRange(); 1084 1085 // Skip over implicit cast expressions when checking for block expressions. 1086 if (ImplicitCastExpr *IcExpr = 1087 dyn_cast_or_null<ImplicitCastExpr>(RetValExp)) 1088 RetValExp = IcExpr->getSubExpr(); 1089 1090 if (BlockExpr *C = dyn_cast_or_null<BlockExpr>(RetValExp)) 1091 if (C->hasBlockDeclRefExprs()) 1092 Diag(C->getLocStart(), diag::err_ret_local_block) 1093 << C->getSourceRange(); 1094 } 1095 // Perform checking for stack values returned by reference. 1096 else if (lhsType->isReferenceType()) { 1097 // Check for a reference to the stack 1098 if (DeclRefExpr *DR = EvalVal(RetValExp)) 1099 Diag(DR->getLocStart(), diag::warn_ret_stack_ref) 1100 << DR->getDecl()->getDeclName() << RetValExp->getSourceRange(); 1101 } 1102} 1103 1104/// EvalAddr - EvalAddr and EvalVal are mutually recursive functions that 1105/// check if the expression in a return statement evaluates to an address 1106/// to a location on the stack. The recursion is used to traverse the 1107/// AST of the return expression, with recursion backtracking when we 1108/// encounter a subexpression that (1) clearly does not lead to the address 1109/// of a stack variable or (2) is something we cannot determine leads to 1110/// the address of a stack variable based on such local checking. 1111/// 1112/// EvalAddr processes expressions that are pointers that are used as 1113/// references (and not L-values). EvalVal handles all other values. 1114/// At the base case of the recursion is a check for a DeclRefExpr* in 1115/// the refers to a stack variable. 1116/// 1117/// This implementation handles: 1118/// 1119/// * pointer-to-pointer casts 1120/// * implicit conversions from array references to pointers 1121/// * taking the address of fields 1122/// * arbitrary interplay between "&" and "*" operators 1123/// * pointer arithmetic from an address of a stack variable 1124/// * taking the address of an array element where the array is on the stack 1125static DeclRefExpr* EvalAddr(Expr *E) { 1126 // We should only be called for evaluating pointer expressions. 1127 assert((E->getType()->isPointerType() || 1128 E->getType()->isBlockPointerType() || 1129 E->getType()->isObjCQualifiedIdType()) && 1130 "EvalAddr only works on pointers"); 1131 1132 // Our "symbolic interpreter" is just a dispatch off the currently 1133 // viewed AST node. We then recursively traverse the AST by calling 1134 // EvalAddr and EvalVal appropriately. 1135 switch (E->getStmtClass()) { 1136 case Stmt::ParenExprClass: 1137 // Ignore parentheses. 1138 return EvalAddr(cast<ParenExpr>(E)->getSubExpr()); 1139 1140 case Stmt::UnaryOperatorClass: { 1141 // The only unary operator that make sense to handle here 1142 // is AddrOf. All others don't make sense as pointers. 1143 UnaryOperator *U = cast<UnaryOperator>(E); 1144 1145 if (U->getOpcode() == UnaryOperator::AddrOf) 1146 return EvalVal(U->getSubExpr()); 1147 else 1148 return NULL; 1149 } 1150 1151 case Stmt::BinaryOperatorClass: { 1152 // Handle pointer arithmetic. All other binary operators are not valid 1153 // in this context. 1154 BinaryOperator *B = cast<BinaryOperator>(E); 1155 BinaryOperator::Opcode op = B->getOpcode(); 1156 1157 if (op != BinaryOperator::Add && op != BinaryOperator::Sub) 1158 return NULL; 1159 1160 Expr *Base = B->getLHS(); 1161 1162 // Determine which argument is the real pointer base. It could be 1163 // the RHS argument instead of the LHS. 1164 if (!Base->getType()->isPointerType()) Base = B->getRHS(); 1165 1166 assert (Base->getType()->isPointerType()); 1167 return EvalAddr(Base); 1168 } 1169 1170 // For conditional operators we need to see if either the LHS or RHS are 1171 // valid DeclRefExpr*s. If one of them is valid, we return it. 1172 case Stmt::ConditionalOperatorClass: { 1173 ConditionalOperator *C = cast<ConditionalOperator>(E); 1174 1175 // Handle the GNU extension for missing LHS. 1176 if (Expr *lhsExpr = C->getLHS()) 1177 if (DeclRefExpr* LHS = EvalAddr(lhsExpr)) 1178 return LHS; 1179 1180 return EvalAddr(C->getRHS()); 1181 } 1182 1183 // For casts, we need to handle conversions from arrays to 1184 // pointer values, and pointer-to-pointer conversions. 1185 case Stmt::ImplicitCastExprClass: 1186 case Stmt::CStyleCastExprClass: 1187 case Stmt::CXXFunctionalCastExprClass: { 1188 Expr* SubExpr = cast<CastExpr>(E)->getSubExpr(); 1189 QualType T = SubExpr->getType(); 1190 1191 if (SubExpr->getType()->isPointerType() || 1192 SubExpr->getType()->isBlockPointerType() || 1193 SubExpr->getType()->isObjCQualifiedIdType()) 1194 return EvalAddr(SubExpr); 1195 else if (T->isArrayType()) 1196 return EvalVal(SubExpr); 1197 else 1198 return 0; 1199 } 1200 1201 // C++ casts. For dynamic casts, static casts, and const casts, we 1202 // are always converting from a pointer-to-pointer, so we just blow 1203 // through the cast. In the case the dynamic cast doesn't fail (and 1204 // return NULL), we take the conservative route and report cases 1205 // where we return the address of a stack variable. For Reinterpre 1206 // FIXME: The comment about is wrong; we're not always converting 1207 // from pointer to pointer. I'm guessing that this code should also 1208 // handle references to objects. 1209 case Stmt::CXXStaticCastExprClass: 1210 case Stmt::CXXDynamicCastExprClass: 1211 case Stmt::CXXConstCastExprClass: 1212 case Stmt::CXXReinterpretCastExprClass: { 1213 Expr *S = cast<CXXNamedCastExpr>(E)->getSubExpr(); 1214 if (S->getType()->isPointerType() || S->getType()->isBlockPointerType()) 1215 return EvalAddr(S); 1216 else 1217 return NULL; 1218 } 1219 1220 // Everything else: we simply don't reason about them. 1221 default: 1222 return NULL; 1223 } 1224} 1225 1226 1227/// EvalVal - This function is complements EvalAddr in the mutual recursion. 1228/// See the comments for EvalAddr for more details. 1229static DeclRefExpr* EvalVal(Expr *E) { 1230 1231 // We should only be called for evaluating non-pointer expressions, or 1232 // expressions with a pointer type that are not used as references but instead 1233 // are l-values (e.g., DeclRefExpr with a pointer type). 1234 1235 // Our "symbolic interpreter" is just a dispatch off the currently 1236 // viewed AST node. We then recursively traverse the AST by calling 1237 // EvalAddr and EvalVal appropriately. 1238 switch (E->getStmtClass()) { 1239 case Stmt::DeclRefExprClass: 1240 case Stmt::QualifiedDeclRefExprClass: { 1241 // DeclRefExpr: the base case. When we hit a DeclRefExpr we are looking 1242 // at code that refers to a variable's name. We check if it has local 1243 // storage within the function, and if so, return the expression. 1244 DeclRefExpr *DR = cast<DeclRefExpr>(E); 1245 1246 if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl())) 1247 if(V->hasLocalStorage() && !V->getType()->isReferenceType()) return DR; 1248 1249 return NULL; 1250 } 1251 1252 case Stmt::ParenExprClass: 1253 // Ignore parentheses. 1254 return EvalVal(cast<ParenExpr>(E)->getSubExpr()); 1255 1256 case Stmt::UnaryOperatorClass: { 1257 // The only unary operator that make sense to handle here 1258 // is Deref. All others don't resolve to a "name." This includes 1259 // handling all sorts of rvalues passed to a unary operator. 1260 UnaryOperator *U = cast<UnaryOperator>(E); 1261 1262 if (U->getOpcode() == UnaryOperator::Deref) 1263 return EvalAddr(U->getSubExpr()); 1264 1265 return NULL; 1266 } 1267 1268 case Stmt::ArraySubscriptExprClass: { 1269 // Array subscripts are potential references to data on the stack. We 1270 // retrieve the DeclRefExpr* for the array variable if it indeed 1271 // has local storage. 1272 return EvalAddr(cast<ArraySubscriptExpr>(E)->getBase()); 1273 } 1274 1275 case Stmt::ConditionalOperatorClass: { 1276 // For conditional operators we need to see if either the LHS or RHS are 1277 // non-NULL DeclRefExpr's. If one is non-NULL, we return it. 1278 ConditionalOperator *C = cast<ConditionalOperator>(E); 1279 1280 // Handle the GNU extension for missing LHS. 1281 if (Expr *lhsExpr = C->getLHS()) 1282 if (DeclRefExpr *LHS = EvalVal(lhsExpr)) 1283 return LHS; 1284 1285 return EvalVal(C->getRHS()); 1286 } 1287 1288 // Accesses to members are potential references to data on the stack. 1289 case Stmt::MemberExprClass: { 1290 MemberExpr *M = cast<MemberExpr>(E); 1291 1292 // Check for indirect access. We only want direct field accesses. 1293 if (!M->isArrow()) 1294 return EvalVal(M->getBase()); 1295 else 1296 return NULL; 1297 } 1298 1299 // Everything else: we simply don't reason about them. 1300 default: 1301 return NULL; 1302 } 1303} 1304 1305//===--- CHECK: Floating-Point comparisons (-Wfloat-equal) ---------------===// 1306 1307/// Check for comparisons of floating point operands using != and ==. 1308/// Issue a warning if these are no self-comparisons, as they are not likely 1309/// to do what the programmer intended. 1310void Sema::CheckFloatComparison(SourceLocation loc, Expr* lex, Expr *rex) { 1311 bool EmitWarning = true; 1312 1313 Expr* LeftExprSansParen = lex->IgnoreParens(); 1314 Expr* RightExprSansParen = rex->IgnoreParens(); 1315 1316 // Special case: check for x == x (which is OK). 1317 // Do not emit warnings for such cases. 1318 if (DeclRefExpr* DRL = dyn_cast<DeclRefExpr>(LeftExprSansParen)) 1319 if (DeclRefExpr* DRR = dyn_cast<DeclRefExpr>(RightExprSansParen)) 1320 if (DRL->getDecl() == DRR->getDecl()) 1321 EmitWarning = false; 1322 1323 1324 // Special case: check for comparisons against literals that can be exactly 1325 // represented by APFloat. In such cases, do not emit a warning. This 1326 // is a heuristic: often comparison against such literals are used to 1327 // detect if a value in a variable has not changed. This clearly can 1328 // lead to false negatives. 1329 if (EmitWarning) { 1330 if (FloatingLiteral* FLL = dyn_cast<FloatingLiteral>(LeftExprSansParen)) { 1331 if (FLL->isExact()) 1332 EmitWarning = false; 1333 } 1334 else 1335 if (FloatingLiteral* FLR = dyn_cast<FloatingLiteral>(RightExprSansParen)){ 1336 if (FLR->isExact()) 1337 EmitWarning = false; 1338 } 1339 } 1340 1341 // Check for comparisons with builtin types. 1342 if (EmitWarning) 1343 if (CallExpr* CL = dyn_cast<CallExpr>(LeftExprSansParen)) 1344 if (CL->isBuiltinCall(Context)) 1345 EmitWarning = false; 1346 1347 if (EmitWarning) 1348 if (CallExpr* CR = dyn_cast<CallExpr>(RightExprSansParen)) 1349 if (CR->isBuiltinCall(Context)) 1350 EmitWarning = false; 1351 1352 // Emit the diagnostic. 1353 if (EmitWarning) 1354 Diag(loc, diag::warn_floatingpoint_eq) 1355 << lex->getSourceRange() << rex->getSourceRange(); 1356} 1357