SemaChecking.cpp revision 199c3d6cd16aebbb9c7f0d42af9d922c9628bf70
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/CharUnits.h" 18#include "clang/AST/DeclObjC.h" 19#include "clang/AST/ExprCXX.h" 20#include "clang/AST/ExprObjC.h" 21#include "clang/Lex/LiteralSupport.h" 22#include "clang/Lex/Preprocessor.h" 23#include <limits> 24using namespace clang; 25 26/// getLocationOfStringLiteralByte - Return a source location that points to the 27/// specified byte of the specified string literal. 28/// 29/// Strings are amazingly complex. They can be formed from multiple tokens and 30/// can have escape sequences in them in addition to the usual trigraph and 31/// escaped newline business. This routine handles this complexity. 32/// 33SourceLocation Sema::getLocationOfStringLiteralByte(const StringLiteral *SL, 34 unsigned ByteNo) const { 35 assert(!SL->isWide() && "This doesn't work for wide strings yet"); 36 37 // Loop over all of the tokens in this string until we find the one that 38 // contains the byte we're looking for. 39 unsigned TokNo = 0; 40 while (1) { 41 assert(TokNo < SL->getNumConcatenated() && "Invalid byte number!"); 42 SourceLocation StrTokLoc = SL->getStrTokenLoc(TokNo); 43 44 // Get the spelling of the string so that we can get the data that makes up 45 // the string literal, not the identifier for the macro it is potentially 46 // expanded through. 47 SourceLocation StrTokSpellingLoc = SourceMgr.getSpellingLoc(StrTokLoc); 48 49 // Re-lex the token to get its length and original spelling. 50 std::pair<FileID, unsigned> LocInfo = 51 SourceMgr.getDecomposedLoc(StrTokSpellingLoc); 52 std::pair<const char *,const char *> Buffer = 53 SourceMgr.getBufferData(LocInfo.first); 54 const char *StrData = Buffer.first+LocInfo.second; 55 56 // Create a langops struct and enable trigraphs. This is sufficient for 57 // relexing tokens. 58 LangOptions LangOpts; 59 LangOpts.Trigraphs = true; 60 61 // Create a lexer starting at the beginning of this token. 62 Lexer TheLexer(StrTokSpellingLoc, LangOpts, Buffer.first, StrData, 63 Buffer.second); 64 Token TheTok; 65 TheLexer.LexFromRawLexer(TheTok); 66 67 // Use the StringLiteralParser to compute the length of the string in bytes. 68 StringLiteralParser SLP(&TheTok, 1, PP); 69 unsigned TokNumBytes = SLP.GetStringLength(); 70 71 // If the byte is in this token, return the location of the byte. 72 if (ByteNo < TokNumBytes || 73 (ByteNo == TokNumBytes && TokNo == SL->getNumConcatenated())) { 74 unsigned Offset = 75 StringLiteralParser::getOffsetOfStringByte(TheTok, ByteNo, PP); 76 77 // Now that we know the offset of the token in the spelling, use the 78 // preprocessor to get the offset in the original source. 79 return PP.AdvanceToTokenCharacter(StrTokLoc, Offset); 80 } 81 82 // Move to the next string token. 83 ++TokNo; 84 ByteNo -= TokNumBytes; 85 } 86} 87 88/// CheckablePrintfAttr - does a function call have a "printf" attribute 89/// and arguments that merit checking? 90bool Sema::CheckablePrintfAttr(const FormatAttr *Format, CallExpr *TheCall) { 91 if (Format->getType() == "printf") return true; 92 if (Format->getType() == "printf0") { 93 // printf0 allows null "format" string; if so don't check format/args 94 unsigned format_idx = Format->getFormatIdx() - 1; 95 // Does the index refer to the implicit object argument? 96 if (isa<CXXMemberCallExpr>(TheCall)) { 97 if (format_idx == 0) 98 return false; 99 --format_idx; 100 } 101 if (format_idx < TheCall->getNumArgs()) { 102 Expr *Format = TheCall->getArg(format_idx)->IgnoreParenCasts(); 103 if (!Format->isNullPointerConstant(Context, Expr::NPC_ValueDependentIsNull)) 104 return true; 105 } 106 } 107 return false; 108} 109 110Action::OwningExprResult 111Sema::CheckBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) { 112 OwningExprResult TheCallResult(Owned(TheCall)); 113 114 switch (BuiltinID) { 115 case Builtin::BI__builtin___CFStringMakeConstantString: 116 assert(TheCall->getNumArgs() == 1 && 117 "Wrong # arguments to builtin CFStringMakeConstantString"); 118 if (CheckObjCString(TheCall->getArg(0))) 119 return ExprError(); 120 break; 121 case Builtin::BI__builtin_stdarg_start: 122 case Builtin::BI__builtin_va_start: 123 if (SemaBuiltinVAStart(TheCall)) 124 return ExprError(); 125 break; 126 case Builtin::BI__builtin_isgreater: 127 case Builtin::BI__builtin_isgreaterequal: 128 case Builtin::BI__builtin_isless: 129 case Builtin::BI__builtin_islessequal: 130 case Builtin::BI__builtin_islessgreater: 131 case Builtin::BI__builtin_isunordered: 132 if (SemaBuiltinUnorderedCompare(TheCall)) 133 return ExprError(); 134 break; 135 case Builtin::BI__builtin_isfinite: 136 case Builtin::BI__builtin_isinf: 137 case Builtin::BI__builtin_isinf_sign: 138 case Builtin::BI__builtin_isnan: 139 case Builtin::BI__builtin_isnormal: 140 if (SemaBuiltinUnaryFP(TheCall)) 141 return ExprError(); 142 break; 143 case Builtin::BI__builtin_return_address: 144 case Builtin::BI__builtin_frame_address: 145 if (SemaBuiltinStackAddress(TheCall)) 146 return ExprError(); 147 break; 148 case Builtin::BI__builtin_eh_return_data_regno: 149 if (SemaBuiltinEHReturnDataRegNo(TheCall)) 150 return ExprError(); 151 break; 152 case Builtin::BI__builtin_shufflevector: 153 return SemaBuiltinShuffleVector(TheCall); 154 // TheCall will be freed by the smart pointer here, but that's fine, since 155 // SemaBuiltinShuffleVector guts it, but then doesn't release it. 156 case Builtin::BI__builtin_prefetch: 157 if (SemaBuiltinPrefetch(TheCall)) 158 return ExprError(); 159 break; 160 case Builtin::BI__builtin_object_size: 161 if (SemaBuiltinObjectSize(TheCall)) 162 return ExprError(); 163 break; 164 case Builtin::BI__builtin_longjmp: 165 if (SemaBuiltinLongjmp(TheCall)) 166 return ExprError(); 167 break; 168 case Builtin::BI__sync_fetch_and_add: 169 case Builtin::BI__sync_fetch_and_sub: 170 case Builtin::BI__sync_fetch_and_or: 171 case Builtin::BI__sync_fetch_and_and: 172 case Builtin::BI__sync_fetch_and_xor: 173 case Builtin::BI__sync_fetch_and_nand: 174 case Builtin::BI__sync_add_and_fetch: 175 case Builtin::BI__sync_sub_and_fetch: 176 case Builtin::BI__sync_and_and_fetch: 177 case Builtin::BI__sync_or_and_fetch: 178 case Builtin::BI__sync_xor_and_fetch: 179 case Builtin::BI__sync_nand_and_fetch: 180 case Builtin::BI__sync_val_compare_and_swap: 181 case Builtin::BI__sync_bool_compare_and_swap: 182 case Builtin::BI__sync_lock_test_and_set: 183 case Builtin::BI__sync_lock_release: 184 if (SemaBuiltinAtomicOverloaded(TheCall)) 185 return ExprError(); 186 break; 187 } 188 189 return move(TheCallResult); 190} 191 192/// CheckFunctionCall - Check a direct function call for various correctness 193/// and safety properties not strictly enforced by the C type system. 194bool Sema::CheckFunctionCall(FunctionDecl *FDecl, CallExpr *TheCall) { 195 // Get the IdentifierInfo* for the called function. 196 IdentifierInfo *FnInfo = FDecl->getIdentifier(); 197 198 // None of the checks below are needed for functions that don't have 199 // simple names (e.g., C++ conversion functions). 200 if (!FnInfo) 201 return false; 202 203 // FIXME: This mechanism should be abstracted to be less fragile and 204 // more efficient. For example, just map function ids to custom 205 // handlers. 206 207 // Printf checking. 208 if (const FormatAttr *Format = FDecl->getAttr<FormatAttr>()) { 209 if (CheckablePrintfAttr(Format, TheCall)) { 210 bool HasVAListArg = Format->getFirstArg() == 0; 211 if (!HasVAListArg) { 212 if (const FunctionProtoType *Proto 213 = FDecl->getType()->getAs<FunctionProtoType>()) 214 HasVAListArg = !Proto->isVariadic(); 215 } 216 CheckPrintfArguments(TheCall, HasVAListArg, Format->getFormatIdx() - 1, 217 HasVAListArg ? 0 : Format->getFirstArg() - 1); 218 } 219 } 220 221 for (const NonNullAttr *NonNull = FDecl->getAttr<NonNullAttr>(); NonNull; 222 NonNull = NonNull->getNext<NonNullAttr>()) 223 CheckNonNullArguments(NonNull, TheCall); 224 225 return false; 226} 227 228bool Sema::CheckBlockCall(NamedDecl *NDecl, CallExpr *TheCall) { 229 // Printf checking. 230 const FormatAttr *Format = NDecl->getAttr<FormatAttr>(); 231 if (!Format) 232 return false; 233 234 const VarDecl *V = dyn_cast<VarDecl>(NDecl); 235 if (!V) 236 return false; 237 238 QualType Ty = V->getType(); 239 if (!Ty->isBlockPointerType()) 240 return false; 241 242 if (!CheckablePrintfAttr(Format, TheCall)) 243 return false; 244 245 bool HasVAListArg = Format->getFirstArg() == 0; 246 if (!HasVAListArg) { 247 const FunctionType *FT = 248 Ty->getAs<BlockPointerType>()->getPointeeType()->getAs<FunctionType>(); 249 if (const FunctionProtoType *Proto = dyn_cast<FunctionProtoType>(FT)) 250 HasVAListArg = !Proto->isVariadic(); 251 } 252 CheckPrintfArguments(TheCall, HasVAListArg, Format->getFormatIdx() - 1, 253 HasVAListArg ? 0 : Format->getFirstArg() - 1); 254 255 return false; 256} 257 258/// SemaBuiltinAtomicOverloaded - We have a call to a function like 259/// __sync_fetch_and_add, which is an overloaded function based on the pointer 260/// type of its first argument. The main ActOnCallExpr routines have already 261/// promoted the types of arguments because all of these calls are prototyped as 262/// void(...). 263/// 264/// This function goes through and does final semantic checking for these 265/// builtins, 266bool Sema::SemaBuiltinAtomicOverloaded(CallExpr *TheCall) { 267 DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts()); 268 FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl()); 269 270 // Ensure that we have at least one argument to do type inference from. 271 if (TheCall->getNumArgs() < 1) 272 return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args) 273 << 0 << TheCall->getCallee()->getSourceRange(); 274 275 // Inspect the first argument of the atomic builtin. This should always be 276 // a pointer type, whose element is an integral scalar or pointer type. 277 // Because it is a pointer type, we don't have to worry about any implicit 278 // casts here. 279 Expr *FirstArg = TheCall->getArg(0); 280 if (!FirstArg->getType()->isPointerType()) 281 return Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer) 282 << FirstArg->getType() << FirstArg->getSourceRange(); 283 284 QualType ValType = FirstArg->getType()->getAs<PointerType>()->getPointeeType(); 285 if (!ValType->isIntegerType() && !ValType->isPointerType() && 286 !ValType->isBlockPointerType()) 287 return Diag(DRE->getLocStart(), 288 diag::err_atomic_builtin_must_be_pointer_intptr) 289 << FirstArg->getType() << FirstArg->getSourceRange(); 290 291 // We need to figure out which concrete builtin this maps onto. For example, 292 // __sync_fetch_and_add with a 2 byte object turns into 293 // __sync_fetch_and_add_2. 294#define BUILTIN_ROW(x) \ 295 { Builtin::BI##x##_1, Builtin::BI##x##_2, Builtin::BI##x##_4, \ 296 Builtin::BI##x##_8, Builtin::BI##x##_16 } 297 298 static const unsigned BuiltinIndices[][5] = { 299 BUILTIN_ROW(__sync_fetch_and_add), 300 BUILTIN_ROW(__sync_fetch_and_sub), 301 BUILTIN_ROW(__sync_fetch_and_or), 302 BUILTIN_ROW(__sync_fetch_and_and), 303 BUILTIN_ROW(__sync_fetch_and_xor), 304 BUILTIN_ROW(__sync_fetch_and_nand), 305 306 BUILTIN_ROW(__sync_add_and_fetch), 307 BUILTIN_ROW(__sync_sub_and_fetch), 308 BUILTIN_ROW(__sync_and_and_fetch), 309 BUILTIN_ROW(__sync_or_and_fetch), 310 BUILTIN_ROW(__sync_xor_and_fetch), 311 BUILTIN_ROW(__sync_nand_and_fetch), 312 313 BUILTIN_ROW(__sync_val_compare_and_swap), 314 BUILTIN_ROW(__sync_bool_compare_and_swap), 315 BUILTIN_ROW(__sync_lock_test_and_set), 316 BUILTIN_ROW(__sync_lock_release) 317 }; 318#undef BUILTIN_ROW 319 320 // Determine the index of the size. 321 unsigned SizeIndex; 322 switch (Context.getTypeSizeInChars(ValType).getQuantity()) { 323 case 1: SizeIndex = 0; break; 324 case 2: SizeIndex = 1; break; 325 case 4: SizeIndex = 2; break; 326 case 8: SizeIndex = 3; break; 327 case 16: SizeIndex = 4; break; 328 default: 329 return Diag(DRE->getLocStart(), diag::err_atomic_builtin_pointer_size) 330 << FirstArg->getType() << FirstArg->getSourceRange(); 331 } 332 333 // Each of these builtins has one pointer argument, followed by some number of 334 // values (0, 1 or 2) followed by a potentially empty varags list of stuff 335 // that we ignore. Find out which row of BuiltinIndices to read from as well 336 // as the number of fixed args. 337 unsigned BuiltinID = FDecl->getBuiltinID(); 338 unsigned BuiltinIndex, NumFixed = 1; 339 switch (BuiltinID) { 340 default: assert(0 && "Unknown overloaded atomic builtin!"); 341 case Builtin::BI__sync_fetch_and_add: BuiltinIndex = 0; break; 342 case Builtin::BI__sync_fetch_and_sub: BuiltinIndex = 1; break; 343 case Builtin::BI__sync_fetch_and_or: BuiltinIndex = 2; break; 344 case Builtin::BI__sync_fetch_and_and: BuiltinIndex = 3; break; 345 case Builtin::BI__sync_fetch_and_xor: BuiltinIndex = 4; break; 346 case Builtin::BI__sync_fetch_and_nand:BuiltinIndex = 5; break; 347 348 case Builtin::BI__sync_add_and_fetch: BuiltinIndex = 6; break; 349 case Builtin::BI__sync_sub_and_fetch: BuiltinIndex = 7; break; 350 case Builtin::BI__sync_and_and_fetch: BuiltinIndex = 8; break; 351 case Builtin::BI__sync_or_and_fetch: BuiltinIndex = 9; break; 352 case Builtin::BI__sync_xor_and_fetch: BuiltinIndex =10; break; 353 case Builtin::BI__sync_nand_and_fetch:BuiltinIndex =11; break; 354 355 case Builtin::BI__sync_val_compare_and_swap: 356 BuiltinIndex = 12; 357 NumFixed = 2; 358 break; 359 case Builtin::BI__sync_bool_compare_and_swap: 360 BuiltinIndex = 13; 361 NumFixed = 2; 362 break; 363 case Builtin::BI__sync_lock_test_and_set: BuiltinIndex = 14; break; 364 case Builtin::BI__sync_lock_release: 365 BuiltinIndex = 15; 366 NumFixed = 0; 367 break; 368 } 369 370 // Now that we know how many fixed arguments we expect, first check that we 371 // have at least that many. 372 if (TheCall->getNumArgs() < 1+NumFixed) 373 return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args) 374 << 0 << TheCall->getCallee()->getSourceRange(); 375 376 377 // Get the decl for the concrete builtin from this, we can tell what the 378 // concrete integer type we should convert to is. 379 unsigned NewBuiltinID = BuiltinIndices[BuiltinIndex][SizeIndex]; 380 const char *NewBuiltinName = Context.BuiltinInfo.GetName(NewBuiltinID); 381 IdentifierInfo *NewBuiltinII = PP.getIdentifierInfo(NewBuiltinName); 382 FunctionDecl *NewBuiltinDecl = 383 cast<FunctionDecl>(LazilyCreateBuiltin(NewBuiltinII, NewBuiltinID, 384 TUScope, false, DRE->getLocStart())); 385 const FunctionProtoType *BuiltinFT = 386 NewBuiltinDecl->getType()->getAs<FunctionProtoType>(); 387 ValType = BuiltinFT->getArgType(0)->getAs<PointerType>()->getPointeeType(); 388 389 // If the first type needs to be converted (e.g. void** -> int*), do it now. 390 if (BuiltinFT->getArgType(0) != FirstArg->getType()) { 391 ImpCastExprToType(FirstArg, BuiltinFT->getArgType(0), CastExpr::CK_BitCast); 392 TheCall->setArg(0, FirstArg); 393 } 394 395 // Next, walk the valid ones promoting to the right type. 396 for (unsigned i = 0; i != NumFixed; ++i) { 397 Expr *Arg = TheCall->getArg(i+1); 398 399 // If the argument is an implicit cast, then there was a promotion due to 400 // "...", just remove it now. 401 if (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Arg)) { 402 Arg = ICE->getSubExpr(); 403 ICE->setSubExpr(0); 404 ICE->Destroy(Context); 405 TheCall->setArg(i+1, Arg); 406 } 407 408 // GCC does an implicit conversion to the pointer or integer ValType. This 409 // can fail in some cases (1i -> int**), check for this error case now. 410 CastExpr::CastKind Kind = CastExpr::CK_Unknown; 411 CXXMethodDecl *ConversionDecl = 0; 412 if (CheckCastTypes(Arg->getSourceRange(), ValType, Arg, Kind, 413 ConversionDecl)) 414 return true; 415 416 // Okay, we have something that *can* be converted to the right type. Check 417 // to see if there is a potentially weird extension going on here. This can 418 // happen when you do an atomic operation on something like an char* and 419 // pass in 42. The 42 gets converted to char. This is even more strange 420 // for things like 45.123 -> char, etc. 421 // FIXME: Do this check. 422 ImpCastExprToType(Arg, ValType, Kind, /*isLvalue=*/false); 423 TheCall->setArg(i+1, Arg); 424 } 425 426 // Switch the DeclRefExpr to refer to the new decl. 427 DRE->setDecl(NewBuiltinDecl); 428 DRE->setType(NewBuiltinDecl->getType()); 429 430 // Set the callee in the CallExpr. 431 // FIXME: This leaks the original parens and implicit casts. 432 Expr *PromotedCall = DRE; 433 UsualUnaryConversions(PromotedCall); 434 TheCall->setCallee(PromotedCall); 435 436 437 // Change the result type of the call to match the result type of the decl. 438 TheCall->setType(NewBuiltinDecl->getResultType()); 439 return false; 440} 441 442 443/// CheckObjCString - Checks that the argument to the builtin 444/// CFString constructor is correct 445/// FIXME: GCC currently emits the following warning: 446/// "warning: input conversion stopped due to an input byte that does not 447/// belong to the input codeset UTF-8" 448/// Note: It might also make sense to do the UTF-16 conversion here (would 449/// simplify the backend). 450bool Sema::CheckObjCString(Expr *Arg) { 451 Arg = Arg->IgnoreParenCasts(); 452 StringLiteral *Literal = dyn_cast<StringLiteral>(Arg); 453 454 if (!Literal || Literal->isWide()) { 455 Diag(Arg->getLocStart(), diag::err_cfstring_literal_not_string_constant) 456 << Arg->getSourceRange(); 457 return true; 458 } 459 460 const char *Data = Literal->getStrData(); 461 unsigned Length = Literal->getByteLength(); 462 463 for (unsigned i = 0; i < Length; ++i) { 464 if (!Data[i]) { 465 Diag(getLocationOfStringLiteralByte(Literal, i), 466 diag::warn_cfstring_literal_contains_nul_character) 467 << Arg->getSourceRange(); 468 break; 469 } 470 } 471 472 return false; 473} 474 475/// SemaBuiltinVAStart - Check the arguments to __builtin_va_start for validity. 476/// Emit an error and return true on failure, return false on success. 477bool Sema::SemaBuiltinVAStart(CallExpr *TheCall) { 478 Expr *Fn = TheCall->getCallee(); 479 if (TheCall->getNumArgs() > 2) { 480 Diag(TheCall->getArg(2)->getLocStart(), 481 diag::err_typecheck_call_too_many_args) 482 << 0 /*function call*/ << Fn->getSourceRange() 483 << SourceRange(TheCall->getArg(2)->getLocStart(), 484 (*(TheCall->arg_end()-1))->getLocEnd()); 485 return true; 486 } 487 488 if (TheCall->getNumArgs() < 2) { 489 return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args) 490 << 0 /*function call*/; 491 } 492 493 // Determine whether the current function is variadic or not. 494 bool isVariadic; 495 if (CurBlock) 496 isVariadic = CurBlock->isVariadic; 497 else if (getCurFunctionDecl()) { 498 if (FunctionProtoType* FTP = 499 dyn_cast<FunctionProtoType>(getCurFunctionDecl()->getType())) 500 isVariadic = FTP->isVariadic(); 501 else 502 isVariadic = false; 503 } else { 504 isVariadic = getCurMethodDecl()->isVariadic(); 505 } 506 507 if (!isVariadic) { 508 Diag(Fn->getLocStart(), diag::err_va_start_used_in_non_variadic_function); 509 return true; 510 } 511 512 // Verify that the second argument to the builtin is the last argument of the 513 // current function or method. 514 bool SecondArgIsLastNamedArgument = false; 515 const Expr *Arg = TheCall->getArg(1)->IgnoreParenCasts(); 516 517 if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Arg)) { 518 if (const ParmVarDecl *PV = dyn_cast<ParmVarDecl>(DR->getDecl())) { 519 // FIXME: This isn't correct for methods (results in bogus warning). 520 // Get the last formal in the current function. 521 const ParmVarDecl *LastArg; 522 if (CurBlock) 523 LastArg = *(CurBlock->TheDecl->param_end()-1); 524 else if (FunctionDecl *FD = getCurFunctionDecl()) 525 LastArg = *(FD->param_end()-1); 526 else 527 LastArg = *(getCurMethodDecl()->param_end()-1); 528 SecondArgIsLastNamedArgument = PV == LastArg; 529 } 530 } 531 532 if (!SecondArgIsLastNamedArgument) 533 Diag(TheCall->getArg(1)->getLocStart(), 534 diag::warn_second_parameter_of_va_start_not_last_named_argument); 535 return false; 536} 537 538/// SemaBuiltinUnorderedCompare - Handle functions like __builtin_isgreater and 539/// friends. This is declared to take (...), so we have to check everything. 540bool Sema::SemaBuiltinUnorderedCompare(CallExpr *TheCall) { 541 if (TheCall->getNumArgs() < 2) 542 return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args) 543 << 0 /*function call*/; 544 if (TheCall->getNumArgs() > 2) 545 return Diag(TheCall->getArg(2)->getLocStart(), 546 diag::err_typecheck_call_too_many_args) 547 << 0 /*function call*/ 548 << SourceRange(TheCall->getArg(2)->getLocStart(), 549 (*(TheCall->arg_end()-1))->getLocEnd()); 550 551 Expr *OrigArg0 = TheCall->getArg(0); 552 Expr *OrigArg1 = TheCall->getArg(1); 553 554 // Do standard promotions between the two arguments, returning their common 555 // type. 556 QualType Res = UsualArithmeticConversions(OrigArg0, OrigArg1, false); 557 558 // Make sure any conversions are pushed back into the call; this is 559 // type safe since unordered compare builtins are declared as "_Bool 560 // foo(...)". 561 TheCall->setArg(0, OrigArg0); 562 TheCall->setArg(1, OrigArg1); 563 564 if (OrigArg0->isTypeDependent() || OrigArg1->isTypeDependent()) 565 return false; 566 567 // If the common type isn't a real floating type, then the arguments were 568 // invalid for this operation. 569 if (!Res->isRealFloatingType()) 570 return Diag(OrigArg0->getLocStart(), 571 diag::err_typecheck_call_invalid_ordered_compare) 572 << OrigArg0->getType() << OrigArg1->getType() 573 << SourceRange(OrigArg0->getLocStart(), OrigArg1->getLocEnd()); 574 575 return false; 576} 577 578/// SemaBuiltinUnorderedCompare - Handle functions like __builtin_isnan and 579/// friends. This is declared to take (...), so we have to check everything. 580bool Sema::SemaBuiltinUnaryFP(CallExpr *TheCall) { 581 if (TheCall->getNumArgs() < 1) 582 return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args) 583 << 0 /*function call*/; 584 if (TheCall->getNumArgs() > 1) 585 return Diag(TheCall->getArg(1)->getLocStart(), 586 diag::err_typecheck_call_too_many_args) 587 << 0 /*function call*/ 588 << SourceRange(TheCall->getArg(1)->getLocStart(), 589 (*(TheCall->arg_end()-1))->getLocEnd()); 590 591 Expr *OrigArg = TheCall->getArg(0); 592 593 if (OrigArg->isTypeDependent()) 594 return false; 595 596 // This operation requires a floating-point number 597 if (!OrigArg->getType()->isRealFloatingType()) 598 return Diag(OrigArg->getLocStart(), 599 diag::err_typecheck_call_invalid_unary_fp) 600 << OrigArg->getType() << OrigArg->getSourceRange(); 601 602 return false; 603} 604 605bool Sema::SemaBuiltinStackAddress(CallExpr *TheCall) { 606 // The signature for these builtins is exact; the only thing we need 607 // to check is that the argument is a constant. 608 SourceLocation Loc; 609 if (!TheCall->getArg(0)->isTypeDependent() && 610 !TheCall->getArg(0)->isValueDependent() && 611 !TheCall->getArg(0)->isIntegerConstantExpr(Context, &Loc)) 612 return Diag(Loc, diag::err_stack_const_level) << TheCall->getSourceRange(); 613 614 return false; 615} 616 617/// SemaBuiltinShuffleVector - Handle __builtin_shufflevector. 618// This is declared to take (...), so we have to check everything. 619Action::OwningExprResult Sema::SemaBuiltinShuffleVector(CallExpr *TheCall) { 620 if (TheCall->getNumArgs() < 3) 621 return ExprError(Diag(TheCall->getLocEnd(), 622 diag::err_typecheck_call_too_few_args) 623 << 0 /*function call*/ << TheCall->getSourceRange()); 624 625 unsigned numElements = std::numeric_limits<unsigned>::max(); 626 if (!TheCall->getArg(0)->isTypeDependent() && 627 !TheCall->getArg(1)->isTypeDependent()) { 628 QualType FAType = TheCall->getArg(0)->getType(); 629 QualType SAType = TheCall->getArg(1)->getType(); 630 631 if (!FAType->isVectorType() || !SAType->isVectorType()) { 632 Diag(TheCall->getLocStart(), diag::err_shufflevector_non_vector) 633 << SourceRange(TheCall->getArg(0)->getLocStart(), 634 TheCall->getArg(1)->getLocEnd()); 635 return ExprError(); 636 } 637 638 if (!Context.hasSameUnqualifiedType(FAType, SAType)) { 639 Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector) 640 << SourceRange(TheCall->getArg(0)->getLocStart(), 641 TheCall->getArg(1)->getLocEnd()); 642 return ExprError(); 643 } 644 645 numElements = FAType->getAs<VectorType>()->getNumElements(); 646 if (TheCall->getNumArgs() != numElements+2) { 647 if (TheCall->getNumArgs() < numElements+2) 648 return ExprError(Diag(TheCall->getLocEnd(), 649 diag::err_typecheck_call_too_few_args) 650 << 0 /*function call*/ << TheCall->getSourceRange()); 651 return ExprError(Diag(TheCall->getLocEnd(), 652 diag::err_typecheck_call_too_many_args) 653 << 0 /*function call*/ << TheCall->getSourceRange()); 654 } 655 } 656 657 for (unsigned i = 2; i < TheCall->getNumArgs(); i++) { 658 if (TheCall->getArg(i)->isTypeDependent() || 659 TheCall->getArg(i)->isValueDependent()) 660 continue; 661 662 llvm::APSInt Result(32); 663 if (!TheCall->getArg(i)->isIntegerConstantExpr(Result, Context)) 664 return ExprError(Diag(TheCall->getLocStart(), 665 diag::err_shufflevector_nonconstant_argument) 666 << TheCall->getArg(i)->getSourceRange()); 667 668 if (Result.getActiveBits() > 64 || Result.getZExtValue() >= numElements*2) 669 return ExprError(Diag(TheCall->getLocStart(), 670 diag::err_shufflevector_argument_too_large) 671 << TheCall->getArg(i)->getSourceRange()); 672 } 673 674 llvm::SmallVector<Expr*, 32> exprs; 675 676 for (unsigned i = 0, e = TheCall->getNumArgs(); i != e; i++) { 677 exprs.push_back(TheCall->getArg(i)); 678 TheCall->setArg(i, 0); 679 } 680 681 return Owned(new (Context) ShuffleVectorExpr(Context, exprs.begin(), 682 exprs.size(), exprs[0]->getType(), 683 TheCall->getCallee()->getLocStart(), 684 TheCall->getRParenLoc())); 685} 686 687/// SemaBuiltinPrefetch - Handle __builtin_prefetch. 688// This is declared to take (const void*, ...) and can take two 689// optional constant int args. 690bool Sema::SemaBuiltinPrefetch(CallExpr *TheCall) { 691 unsigned NumArgs = TheCall->getNumArgs(); 692 693 if (NumArgs > 3) 694 return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_many_args) 695 << 0 /*function call*/ << TheCall->getSourceRange(); 696 697 // Argument 0 is checked for us and the remaining arguments must be 698 // constant integers. 699 for (unsigned i = 1; i != NumArgs; ++i) { 700 Expr *Arg = TheCall->getArg(i); 701 if (Arg->isTypeDependent()) 702 continue; 703 704 if (!Arg->getType()->isIntegralType()) 705 return Diag(TheCall->getLocStart(), diag::err_prefetch_invalid_arg_type) 706 << Arg->getSourceRange(); 707 708 ImpCastExprToType(Arg, Context.IntTy, CastExpr::CK_IntegralCast); 709 TheCall->setArg(i, Arg); 710 711 if (Arg->isValueDependent()) 712 continue; 713 714 llvm::APSInt Result; 715 if (!Arg->isIntegerConstantExpr(Result, Context)) 716 return Diag(TheCall->getLocStart(), diag::err_prefetch_invalid_arg_ice) 717 << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); 718 719 // FIXME: gcc issues a warning and rewrites these to 0. These 720 // seems especially odd for the third argument since the default 721 // is 3. 722 if (i == 1) { 723 if (Result.getLimitedValue() > 1) 724 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 725 << "0" << "1" << Arg->getSourceRange(); 726 } else { 727 if (Result.getLimitedValue() > 3) 728 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 729 << "0" << "3" << Arg->getSourceRange(); 730 } 731 } 732 733 return false; 734} 735 736/// SemaBuiltinEHReturnDataRegNo - Handle __builtin_eh_return_data_regno, the 737/// operand must be an integer constant. 738bool Sema::SemaBuiltinEHReturnDataRegNo(CallExpr *TheCall) { 739 llvm::APSInt Result; 740 if (!TheCall->getArg(0)->isIntegerConstantExpr(Result, Context)) 741 return Diag(TheCall->getLocStart(), diag::err_expr_not_ice) 742 << TheCall->getArg(0)->getSourceRange(); 743 744 return false; 745} 746 747 748/// SemaBuiltinObjectSize - Handle __builtin_object_size(void *ptr, 749/// int type). This simply type checks that type is one of the defined 750/// constants (0-3). 751// For compatability check 0-3, llvm only handles 0 and 2. 752bool Sema::SemaBuiltinObjectSize(CallExpr *TheCall) { 753 Expr *Arg = TheCall->getArg(1); 754 if (Arg->isTypeDependent()) 755 return false; 756 757 QualType ArgType = Arg->getType(); 758 const BuiltinType *BT = ArgType->getAs<BuiltinType>(); 759 llvm::APSInt Result(32); 760 if (!BT || BT->getKind() != BuiltinType::Int) 761 return Diag(TheCall->getLocStart(), diag::err_object_size_invalid_argument) 762 << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); 763 764 if (Arg->isValueDependent()) 765 return false; 766 767 if (!Arg->isIntegerConstantExpr(Result, Context)) { 768 return Diag(TheCall->getLocStart(), diag::err_object_size_invalid_argument) 769 << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); 770 } 771 772 if (Result.getSExtValue() < 0 || Result.getSExtValue() > 3) { 773 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 774 << "0" << "3" << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); 775 } 776 777 return false; 778} 779 780/// SemaBuiltinLongjmp - Handle __builtin_longjmp(void *env[5], int val). 781/// This checks that val is a constant 1. 782bool Sema::SemaBuiltinLongjmp(CallExpr *TheCall) { 783 Expr *Arg = TheCall->getArg(1); 784 if (Arg->isTypeDependent() || Arg->isValueDependent()) 785 return false; 786 787 llvm::APSInt Result(32); 788 if (!Arg->isIntegerConstantExpr(Result, Context) || Result != 1) 789 return Diag(TheCall->getLocStart(), diag::err_builtin_longjmp_invalid_val) 790 << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); 791 792 return false; 793} 794 795// Handle i > 1 ? "x" : "y", recursivelly 796bool Sema::SemaCheckStringLiteral(const Expr *E, const CallExpr *TheCall, 797 bool HasVAListArg, 798 unsigned format_idx, unsigned firstDataArg) { 799 if (E->isTypeDependent() || E->isValueDependent()) 800 return false; 801 802 switch (E->getStmtClass()) { 803 case Stmt::ConditionalOperatorClass: { 804 const ConditionalOperator *C = cast<ConditionalOperator>(E); 805 return SemaCheckStringLiteral(C->getTrueExpr(), TheCall, 806 HasVAListArg, format_idx, firstDataArg) 807 && SemaCheckStringLiteral(C->getRHS(), TheCall, 808 HasVAListArg, format_idx, firstDataArg); 809 } 810 811 case Stmt::ImplicitCastExprClass: { 812 const ImplicitCastExpr *Expr = cast<ImplicitCastExpr>(E); 813 return SemaCheckStringLiteral(Expr->getSubExpr(), TheCall, HasVAListArg, 814 format_idx, firstDataArg); 815 } 816 817 case Stmt::ParenExprClass: { 818 const ParenExpr *Expr = cast<ParenExpr>(E); 819 return SemaCheckStringLiteral(Expr->getSubExpr(), TheCall, HasVAListArg, 820 format_idx, firstDataArg); 821 } 822 823 case Stmt::DeclRefExprClass: { 824 const DeclRefExpr *DR = cast<DeclRefExpr>(E); 825 826 // As an exception, do not flag errors for variables binding to 827 // const string literals. 828 if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) { 829 bool isConstant = false; 830 QualType T = DR->getType(); 831 832 if (const ArrayType *AT = Context.getAsArrayType(T)) { 833 isConstant = AT->getElementType().isConstant(Context); 834 } else if (const PointerType *PT = T->getAs<PointerType>()) { 835 isConstant = T.isConstant(Context) && 836 PT->getPointeeType().isConstant(Context); 837 } 838 839 if (isConstant) { 840 const VarDecl *Def = 0; 841 if (const Expr *Init = VD->getDefinition(Def)) 842 return SemaCheckStringLiteral(Init, TheCall, 843 HasVAListArg, format_idx, firstDataArg); 844 } 845 846 // For vprintf* functions (i.e., HasVAListArg==true), we add a 847 // special check to see if the format string is a function parameter 848 // of the function calling the printf function. If the function 849 // has an attribute indicating it is a printf-like function, then we 850 // should suppress warnings concerning non-literals being used in a call 851 // to a vprintf function. For example: 852 // 853 // void 854 // logmessage(char const *fmt __attribute__ (format (printf, 1, 2)), ...){ 855 // va_list ap; 856 // va_start(ap, fmt); 857 // vprintf(fmt, ap); // Do NOT emit a warning about "fmt". 858 // ... 859 // 860 // 861 // FIXME: We don't have full attribute support yet, so just check to see 862 // if the argument is a DeclRefExpr that references a parameter. We'll 863 // add proper support for checking the attribute later. 864 if (HasVAListArg) 865 if (isa<ParmVarDecl>(VD)) 866 return true; 867 } 868 869 return false; 870 } 871 872 case Stmt::CallExprClass: { 873 const CallExpr *CE = cast<CallExpr>(E); 874 if (const ImplicitCastExpr *ICE 875 = dyn_cast<ImplicitCastExpr>(CE->getCallee())) { 876 if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(ICE->getSubExpr())) { 877 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(DRE->getDecl())) { 878 if (const FormatArgAttr *FA = FD->getAttr<FormatArgAttr>()) { 879 unsigned ArgIndex = FA->getFormatIdx(); 880 const Expr *Arg = CE->getArg(ArgIndex - 1); 881 882 return SemaCheckStringLiteral(Arg, TheCall, HasVAListArg, 883 format_idx, firstDataArg); 884 } 885 } 886 } 887 } 888 889 return false; 890 } 891 case Stmt::ObjCStringLiteralClass: 892 case Stmt::StringLiteralClass: { 893 const StringLiteral *StrE = NULL; 894 895 if (const ObjCStringLiteral *ObjCFExpr = dyn_cast<ObjCStringLiteral>(E)) 896 StrE = ObjCFExpr->getString(); 897 else 898 StrE = cast<StringLiteral>(E); 899 900 if (StrE) { 901 CheckPrintfString(StrE, E, TheCall, HasVAListArg, format_idx, 902 firstDataArg); 903 return true; 904 } 905 906 return false; 907 } 908 909 default: 910 return false; 911 } 912} 913 914void 915Sema::CheckNonNullArguments(const NonNullAttr *NonNull, 916 const CallExpr *TheCall) { 917 for (NonNullAttr::iterator i = NonNull->begin(), e = NonNull->end(); 918 i != e; ++i) { 919 const Expr *ArgExpr = TheCall->getArg(*i); 920 if (ArgExpr->isNullPointerConstant(Context, 921 Expr::NPC_ValueDependentIsNotNull)) 922 Diag(TheCall->getCallee()->getLocStart(), diag::warn_null_arg) 923 << ArgExpr->getSourceRange(); 924 } 925} 926 927/// CheckPrintfArguments - Check calls to printf (and similar functions) for 928/// correct use of format strings. 929/// 930/// HasVAListArg - A predicate indicating whether the printf-like 931/// function is passed an explicit va_arg argument (e.g., vprintf) 932/// 933/// format_idx - The index into Args for the format string. 934/// 935/// Improper format strings to functions in the printf family can be 936/// the source of bizarre bugs and very serious security holes. A 937/// good source of information is available in the following paper 938/// (which includes additional references): 939/// 940/// FormatGuard: Automatic Protection From printf Format String 941/// Vulnerabilities, Proceedings of the 10th USENIX Security Symposium, 2001. 942/// 943/// Functionality implemented: 944/// 945/// We can statically check the following properties for string 946/// literal format strings for non v.*printf functions (where the 947/// arguments are passed directly): 948// 949/// (1) Are the number of format conversions equal to the number of 950/// data arguments? 951/// 952/// (2) Does each format conversion correctly match the type of the 953/// corresponding data argument? (TODO) 954/// 955/// Moreover, for all printf functions we can: 956/// 957/// (3) Check for a missing format string (when not caught by type checking). 958/// 959/// (4) Check for no-operation flags; e.g. using "#" with format 960/// conversion 'c' (TODO) 961/// 962/// (5) Check the use of '%n', a major source of security holes. 963/// 964/// (6) Check for malformed format conversions that don't specify anything. 965/// 966/// (7) Check for empty format strings. e.g: printf(""); 967/// 968/// (8) Check that the format string is a wide literal. 969/// 970/// All of these checks can be done by parsing the format string. 971/// 972/// For now, we ONLY do (1), (3), (5), (6), (7), and (8). 973void 974Sema::CheckPrintfArguments(const CallExpr *TheCall, bool HasVAListArg, 975 unsigned format_idx, unsigned firstDataArg) { 976 const Expr *Fn = TheCall->getCallee(); 977 978 // The way the format attribute works in GCC, the implicit this argument 979 // of member functions is counted. However, it doesn't appear in our own 980 // lists, so decrement format_idx in that case. 981 if (isa<CXXMemberCallExpr>(TheCall)) { 982 // Catch a format attribute mistakenly referring to the object argument. 983 if (format_idx == 0) 984 return; 985 --format_idx; 986 if(firstDataArg != 0) 987 --firstDataArg; 988 } 989 990 // CHECK: printf-like function is called with no format string. 991 if (format_idx >= TheCall->getNumArgs()) { 992 Diag(TheCall->getRParenLoc(), diag::warn_printf_missing_format_string) 993 << Fn->getSourceRange(); 994 return; 995 } 996 997 const Expr *OrigFormatExpr = TheCall->getArg(format_idx)->IgnoreParenCasts(); 998 999 // CHECK: format string is not a string literal. 1000 // 1001 // Dynamically generated format strings are difficult to 1002 // automatically vet at compile time. Requiring that format strings 1003 // are string literals: (1) permits the checking of format strings by 1004 // the compiler and thereby (2) can practically remove the source of 1005 // many format string exploits. 1006 1007 // Format string can be either ObjC string (e.g. @"%d") or 1008 // C string (e.g. "%d") 1009 // ObjC string uses the same format specifiers as C string, so we can use 1010 // the same format string checking logic for both ObjC and C strings. 1011 if (SemaCheckStringLiteral(OrigFormatExpr, TheCall, HasVAListArg, format_idx, 1012 firstDataArg)) 1013 return; // Literal format string found, check done! 1014 1015 // If there are no arguments specified, warn with -Wformat-security, otherwise 1016 // warn only with -Wformat-nonliteral. 1017 if (TheCall->getNumArgs() == format_idx+1) 1018 Diag(TheCall->getArg(format_idx)->getLocStart(), 1019 diag::warn_printf_nonliteral_noargs) 1020 << OrigFormatExpr->getSourceRange(); 1021 else 1022 Diag(TheCall->getArg(format_idx)->getLocStart(), 1023 diag::warn_printf_nonliteral) 1024 << OrigFormatExpr->getSourceRange(); 1025} 1026 1027void Sema::CheckPrintfString(const StringLiteral *FExpr, 1028 const Expr *OrigFormatExpr, 1029 const CallExpr *TheCall, bool HasVAListArg, 1030 unsigned format_idx, unsigned firstDataArg) { 1031 1032 const ObjCStringLiteral *ObjCFExpr = 1033 dyn_cast<ObjCStringLiteral>(OrigFormatExpr); 1034 1035 // CHECK: is the format string a wide literal? 1036 if (FExpr->isWide()) { 1037 Diag(FExpr->getLocStart(), 1038 diag::warn_printf_format_string_is_wide_literal) 1039 << OrigFormatExpr->getSourceRange(); 1040 return; 1041 } 1042 1043 // Str - The format string. NOTE: this is NOT null-terminated! 1044 const char *Str = FExpr->getStrData(); 1045 1046 // CHECK: empty format string? 1047 unsigned StrLen = FExpr->getByteLength(); 1048 1049 if (StrLen == 0) { 1050 Diag(FExpr->getLocStart(), diag::warn_printf_empty_format_string) 1051 << OrigFormatExpr->getSourceRange(); 1052 return; 1053 } 1054 1055 // We process the format string using a binary state machine. The 1056 // current state is stored in CurrentState. 1057 enum { 1058 state_OrdChr, 1059 state_Conversion 1060 } CurrentState = state_OrdChr; 1061 1062 // numConversions - The number of conversions seen so far. This is 1063 // incremented as we traverse the format string. 1064 unsigned numConversions = 0; 1065 1066 // numDataArgs - The number of data arguments after the format 1067 // string. This can only be determined for non vprintf-like 1068 // functions. For those functions, this value is 1 (the sole 1069 // va_arg argument). 1070 unsigned numDataArgs = TheCall->getNumArgs()-firstDataArg; 1071 1072 // Inspect the format string. 1073 unsigned StrIdx = 0; 1074 1075 // LastConversionIdx - Index within the format string where we last saw 1076 // a '%' character that starts a new format conversion. 1077 unsigned LastConversionIdx = 0; 1078 1079 for (; StrIdx < StrLen; ++StrIdx) { 1080 1081 // Is the number of detected conversion conversions greater than 1082 // the number of matching data arguments? If so, stop. 1083 if (!HasVAListArg && numConversions > numDataArgs) break; 1084 1085 // Handle "\0" 1086 if (Str[StrIdx] == '\0') { 1087 // The string returned by getStrData() is not null-terminated, 1088 // so the presence of a null character is likely an error. 1089 Diag(getLocationOfStringLiteralByte(FExpr, StrIdx), 1090 diag::warn_printf_format_string_contains_null_char) 1091 << OrigFormatExpr->getSourceRange(); 1092 return; 1093 } 1094 1095 // Ordinary characters (not processing a format conversion). 1096 if (CurrentState == state_OrdChr) { 1097 if (Str[StrIdx] == '%') { 1098 CurrentState = state_Conversion; 1099 LastConversionIdx = StrIdx; 1100 } 1101 continue; 1102 } 1103 1104 // Seen '%'. Now processing a format conversion. 1105 switch (Str[StrIdx]) { 1106 // Handle dynamic precision or width specifier. 1107 case '*': { 1108 ++numConversions; 1109 1110 if (!HasVAListArg) { 1111 if (numConversions > numDataArgs) { 1112 SourceLocation Loc = getLocationOfStringLiteralByte(FExpr, StrIdx); 1113 1114 if (Str[StrIdx-1] == '.') 1115 Diag(Loc, diag::warn_printf_asterisk_precision_missing_arg) 1116 << OrigFormatExpr->getSourceRange(); 1117 else 1118 Diag(Loc, diag::warn_printf_asterisk_width_missing_arg) 1119 << OrigFormatExpr->getSourceRange(); 1120 1121 // Don't do any more checking. We'll just emit spurious errors. 1122 return; 1123 } 1124 1125 // Perform type checking on width/precision specifier. 1126 const Expr *E = TheCall->getArg(format_idx+numConversions); 1127 if (const BuiltinType *BT = E->getType()->getAs<BuiltinType>()) 1128 if (BT->getKind() == BuiltinType::Int) 1129 break; 1130 1131 SourceLocation Loc = getLocationOfStringLiteralByte(FExpr, StrIdx); 1132 1133 if (Str[StrIdx-1] == '.') 1134 Diag(Loc, diag::warn_printf_asterisk_precision_wrong_type) 1135 << E->getType() << E->getSourceRange(); 1136 else 1137 Diag(Loc, diag::warn_printf_asterisk_width_wrong_type) 1138 << E->getType() << E->getSourceRange(); 1139 1140 break; 1141 } 1142 } 1143 1144 // Characters which can terminate a format conversion 1145 // (e.g. "%d"). Characters that specify length modifiers or 1146 // other flags are handled by the default case below. 1147 // 1148 // FIXME: additional checks will go into the following cases. 1149 case 'i': 1150 case 'd': 1151 case 'o': 1152 case 'u': 1153 case 'x': 1154 case 'X': 1155 case 'D': 1156 case 'O': 1157 case 'U': 1158 case 'e': 1159 case 'E': 1160 case 'f': 1161 case 'F': 1162 case 'g': 1163 case 'G': 1164 case 'a': 1165 case 'A': 1166 case 'c': 1167 case 'C': 1168 case 'S': 1169 case 's': 1170 case 'p': 1171 ++numConversions; 1172 CurrentState = state_OrdChr; 1173 break; 1174 1175 case 'm': 1176 // FIXME: Warn in situations where this isn't supported! 1177 CurrentState = state_OrdChr; 1178 break; 1179 1180 // CHECK: Are we using "%n"? Issue a warning. 1181 case 'n': { 1182 ++numConversions; 1183 CurrentState = state_OrdChr; 1184 SourceLocation Loc = getLocationOfStringLiteralByte(FExpr, 1185 LastConversionIdx); 1186 1187 Diag(Loc, diag::warn_printf_write_back)<<OrigFormatExpr->getSourceRange(); 1188 break; 1189 } 1190 1191 // Handle "%@" 1192 case '@': 1193 // %@ is allowed in ObjC format strings only. 1194 if (ObjCFExpr != NULL) 1195 CurrentState = state_OrdChr; 1196 else { 1197 // Issue a warning: invalid format conversion. 1198 SourceLocation Loc = 1199 getLocationOfStringLiteralByte(FExpr, LastConversionIdx); 1200 1201 Diag(Loc, diag::warn_printf_invalid_conversion) 1202 << std::string(Str+LastConversionIdx, 1203 Str+std::min(LastConversionIdx+2, StrLen)) 1204 << OrigFormatExpr->getSourceRange(); 1205 } 1206 ++numConversions; 1207 break; 1208 1209 // Handle "%%" 1210 case '%': 1211 // Sanity check: Was the first "%" character the previous one? 1212 // If not, we will assume that we have a malformed format 1213 // conversion, and that the current "%" character is the start 1214 // of a new conversion. 1215 if (StrIdx - LastConversionIdx == 1) 1216 CurrentState = state_OrdChr; 1217 else { 1218 // Issue a warning: invalid format conversion. 1219 SourceLocation Loc = 1220 getLocationOfStringLiteralByte(FExpr, LastConversionIdx); 1221 1222 Diag(Loc, diag::warn_printf_invalid_conversion) 1223 << std::string(Str+LastConversionIdx, Str+StrIdx) 1224 << OrigFormatExpr->getSourceRange(); 1225 1226 // This conversion is broken. Advance to the next format 1227 // conversion. 1228 LastConversionIdx = StrIdx; 1229 ++numConversions; 1230 } 1231 break; 1232 1233 default: 1234 // This case catches all other characters: flags, widths, etc. 1235 // We should eventually process those as well. 1236 break; 1237 } 1238 } 1239 1240 if (CurrentState == state_Conversion) { 1241 // Issue a warning: invalid format conversion. 1242 SourceLocation Loc = 1243 getLocationOfStringLiteralByte(FExpr, LastConversionIdx); 1244 1245 Diag(Loc, diag::warn_printf_invalid_conversion) 1246 << std::string(Str+LastConversionIdx, 1247 Str+std::min(LastConversionIdx+2, StrLen)) 1248 << OrigFormatExpr->getSourceRange(); 1249 return; 1250 } 1251 1252 if (!HasVAListArg) { 1253 // CHECK: Does the number of format conversions exceed the number 1254 // of data arguments? 1255 if (numConversions > numDataArgs) { 1256 SourceLocation Loc = 1257 getLocationOfStringLiteralByte(FExpr, LastConversionIdx); 1258 1259 Diag(Loc, diag::warn_printf_insufficient_data_args) 1260 << OrigFormatExpr->getSourceRange(); 1261 } 1262 // CHECK: Does the number of data arguments exceed the number of 1263 // format conversions in the format string? 1264 else if (numConversions < numDataArgs) 1265 Diag(TheCall->getArg(format_idx+numConversions+1)->getLocStart(), 1266 diag::warn_printf_too_many_data_args) 1267 << OrigFormatExpr->getSourceRange(); 1268 } 1269} 1270 1271//===--- CHECK: Return Address of Stack Variable --------------------------===// 1272 1273static DeclRefExpr* EvalVal(Expr *E); 1274static DeclRefExpr* EvalAddr(Expr* E); 1275 1276/// CheckReturnStackAddr - Check if a return statement returns the address 1277/// of a stack variable. 1278void 1279Sema::CheckReturnStackAddr(Expr *RetValExp, QualType lhsType, 1280 SourceLocation ReturnLoc) { 1281 1282 // Perform checking for returned stack addresses. 1283 if (lhsType->isPointerType() || lhsType->isBlockPointerType()) { 1284 if (DeclRefExpr *DR = EvalAddr(RetValExp)) 1285 Diag(DR->getLocStart(), diag::warn_ret_stack_addr) 1286 << DR->getDecl()->getDeclName() << RetValExp->getSourceRange(); 1287 1288 // Skip over implicit cast expressions when checking for block expressions. 1289 RetValExp = RetValExp->IgnoreParenCasts(); 1290 1291 if (BlockExpr *C = dyn_cast<BlockExpr>(RetValExp)) 1292 if (C->hasBlockDeclRefExprs()) 1293 Diag(C->getLocStart(), diag::err_ret_local_block) 1294 << C->getSourceRange(); 1295 1296 if (AddrLabelExpr *ALE = dyn_cast<AddrLabelExpr>(RetValExp)) 1297 Diag(ALE->getLocStart(), diag::warn_ret_addr_label) 1298 << ALE->getSourceRange(); 1299 1300 } else if (lhsType->isReferenceType()) { 1301 // Perform checking for stack values returned by reference. 1302 // Check for a reference to the stack 1303 if (DeclRefExpr *DR = EvalVal(RetValExp)) 1304 Diag(DR->getLocStart(), diag::warn_ret_stack_ref) 1305 << DR->getDecl()->getDeclName() << RetValExp->getSourceRange(); 1306 } 1307} 1308 1309/// EvalAddr - EvalAddr and EvalVal are mutually recursive functions that 1310/// check if the expression in a return statement evaluates to an address 1311/// to a location on the stack. The recursion is used to traverse the 1312/// AST of the return expression, with recursion backtracking when we 1313/// encounter a subexpression that (1) clearly does not lead to the address 1314/// of a stack variable or (2) is something we cannot determine leads to 1315/// the address of a stack variable based on such local checking. 1316/// 1317/// EvalAddr processes expressions that are pointers that are used as 1318/// references (and not L-values). EvalVal handles all other values. 1319/// At the base case of the recursion is a check for a DeclRefExpr* in 1320/// the refers to a stack variable. 1321/// 1322/// This implementation handles: 1323/// 1324/// * pointer-to-pointer casts 1325/// * implicit conversions from array references to pointers 1326/// * taking the address of fields 1327/// * arbitrary interplay between "&" and "*" operators 1328/// * pointer arithmetic from an address of a stack variable 1329/// * taking the address of an array element where the array is on the stack 1330static DeclRefExpr* EvalAddr(Expr *E) { 1331 // We should only be called for evaluating pointer expressions. 1332 assert((E->getType()->isAnyPointerType() || 1333 E->getType()->isBlockPointerType() || 1334 E->getType()->isObjCQualifiedIdType()) && 1335 "EvalAddr only works on pointers"); 1336 1337 // Our "symbolic interpreter" is just a dispatch off the currently 1338 // viewed AST node. We then recursively traverse the AST by calling 1339 // EvalAddr and EvalVal appropriately. 1340 switch (E->getStmtClass()) { 1341 case Stmt::ParenExprClass: 1342 // Ignore parentheses. 1343 return EvalAddr(cast<ParenExpr>(E)->getSubExpr()); 1344 1345 case Stmt::UnaryOperatorClass: { 1346 // The only unary operator that make sense to handle here 1347 // is AddrOf. All others don't make sense as pointers. 1348 UnaryOperator *U = cast<UnaryOperator>(E); 1349 1350 if (U->getOpcode() == UnaryOperator::AddrOf) 1351 return EvalVal(U->getSubExpr()); 1352 else 1353 return NULL; 1354 } 1355 1356 case Stmt::BinaryOperatorClass: { 1357 // Handle pointer arithmetic. All other binary operators are not valid 1358 // in this context. 1359 BinaryOperator *B = cast<BinaryOperator>(E); 1360 BinaryOperator::Opcode op = B->getOpcode(); 1361 1362 if (op != BinaryOperator::Add && op != BinaryOperator::Sub) 1363 return NULL; 1364 1365 Expr *Base = B->getLHS(); 1366 1367 // Determine which argument is the real pointer base. It could be 1368 // the RHS argument instead of the LHS. 1369 if (!Base->getType()->isPointerType()) Base = B->getRHS(); 1370 1371 assert (Base->getType()->isPointerType()); 1372 return EvalAddr(Base); 1373 } 1374 1375 // For conditional operators we need to see if either the LHS or RHS are 1376 // valid DeclRefExpr*s. If one of them is valid, we return it. 1377 case Stmt::ConditionalOperatorClass: { 1378 ConditionalOperator *C = cast<ConditionalOperator>(E); 1379 1380 // Handle the GNU extension for missing LHS. 1381 if (Expr *lhsExpr = C->getLHS()) 1382 if (DeclRefExpr* LHS = EvalAddr(lhsExpr)) 1383 return LHS; 1384 1385 return EvalAddr(C->getRHS()); 1386 } 1387 1388 // For casts, we need to handle conversions from arrays to 1389 // pointer values, and pointer-to-pointer conversions. 1390 case Stmt::ImplicitCastExprClass: 1391 case Stmt::CStyleCastExprClass: 1392 case Stmt::CXXFunctionalCastExprClass: { 1393 Expr* SubExpr = cast<CastExpr>(E)->getSubExpr(); 1394 QualType T = SubExpr->getType(); 1395 1396 if (SubExpr->getType()->isPointerType() || 1397 SubExpr->getType()->isBlockPointerType() || 1398 SubExpr->getType()->isObjCQualifiedIdType()) 1399 return EvalAddr(SubExpr); 1400 else if (T->isArrayType()) 1401 return EvalVal(SubExpr); 1402 else 1403 return 0; 1404 } 1405 1406 // C++ casts. For dynamic casts, static casts, and const casts, we 1407 // are always converting from a pointer-to-pointer, so we just blow 1408 // through the cast. In the case the dynamic cast doesn't fail (and 1409 // return NULL), we take the conservative route and report cases 1410 // where we return the address of a stack variable. For Reinterpre 1411 // FIXME: The comment about is wrong; we're not always converting 1412 // from pointer to pointer. I'm guessing that this code should also 1413 // handle references to objects. 1414 case Stmt::CXXStaticCastExprClass: 1415 case Stmt::CXXDynamicCastExprClass: 1416 case Stmt::CXXConstCastExprClass: 1417 case Stmt::CXXReinterpretCastExprClass: { 1418 Expr *S = cast<CXXNamedCastExpr>(E)->getSubExpr(); 1419 if (S->getType()->isPointerType() || S->getType()->isBlockPointerType()) 1420 return EvalAddr(S); 1421 else 1422 return NULL; 1423 } 1424 1425 // Everything else: we simply don't reason about them. 1426 default: 1427 return NULL; 1428 } 1429} 1430 1431 1432/// EvalVal - This function is complements EvalAddr in the mutual recursion. 1433/// See the comments for EvalAddr for more details. 1434static DeclRefExpr* EvalVal(Expr *E) { 1435 1436 // We should only be called for evaluating non-pointer expressions, or 1437 // expressions with a pointer type that are not used as references but instead 1438 // are l-values (e.g., DeclRefExpr with a pointer type). 1439 1440 // Our "symbolic interpreter" is just a dispatch off the currently 1441 // viewed AST node. We then recursively traverse the AST by calling 1442 // EvalAddr and EvalVal appropriately. 1443 switch (E->getStmtClass()) { 1444 case Stmt::DeclRefExprClass: { 1445 // DeclRefExpr: the base case. When we hit a DeclRefExpr we are looking 1446 // at code that refers to a variable's name. We check if it has local 1447 // storage within the function, and if so, return the expression. 1448 DeclRefExpr *DR = cast<DeclRefExpr>(E); 1449 1450 if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl())) 1451 if (V->hasLocalStorage() && !V->getType()->isReferenceType()) return DR; 1452 1453 return NULL; 1454 } 1455 1456 case Stmt::ParenExprClass: 1457 // Ignore parentheses. 1458 return EvalVal(cast<ParenExpr>(E)->getSubExpr()); 1459 1460 case Stmt::UnaryOperatorClass: { 1461 // The only unary operator that make sense to handle here 1462 // is Deref. All others don't resolve to a "name." This includes 1463 // handling all sorts of rvalues passed to a unary operator. 1464 UnaryOperator *U = cast<UnaryOperator>(E); 1465 1466 if (U->getOpcode() == UnaryOperator::Deref) 1467 return EvalAddr(U->getSubExpr()); 1468 1469 return NULL; 1470 } 1471 1472 case Stmt::ArraySubscriptExprClass: { 1473 // Array subscripts are potential references to data on the stack. We 1474 // retrieve the DeclRefExpr* for the array variable if it indeed 1475 // has local storage. 1476 return EvalAddr(cast<ArraySubscriptExpr>(E)->getBase()); 1477 } 1478 1479 case Stmt::ConditionalOperatorClass: { 1480 // For conditional operators we need to see if either the LHS or RHS are 1481 // non-NULL DeclRefExpr's. If one is non-NULL, we return it. 1482 ConditionalOperator *C = cast<ConditionalOperator>(E); 1483 1484 // Handle the GNU extension for missing LHS. 1485 if (Expr *lhsExpr = C->getLHS()) 1486 if (DeclRefExpr *LHS = EvalVal(lhsExpr)) 1487 return LHS; 1488 1489 return EvalVal(C->getRHS()); 1490 } 1491 1492 // Accesses to members are potential references to data on the stack. 1493 case Stmt::MemberExprClass: { 1494 MemberExpr *M = cast<MemberExpr>(E); 1495 1496 // Check for indirect access. We only want direct field accesses. 1497 if (!M->isArrow()) 1498 return EvalVal(M->getBase()); 1499 else 1500 return NULL; 1501 } 1502 1503 // Everything else: we simply don't reason about them. 1504 default: 1505 return NULL; 1506 } 1507} 1508 1509//===--- CHECK: Floating-Point comparisons (-Wfloat-equal) ---------------===// 1510 1511/// Check for comparisons of floating point operands using != and ==. 1512/// Issue a warning if these are no self-comparisons, as they are not likely 1513/// to do what the programmer intended. 1514void Sema::CheckFloatComparison(SourceLocation loc, Expr* lex, Expr *rex) { 1515 bool EmitWarning = true; 1516 1517 Expr* LeftExprSansParen = lex->IgnoreParens(); 1518 Expr* RightExprSansParen = rex->IgnoreParens(); 1519 1520 // Special case: check for x == x (which is OK). 1521 // Do not emit warnings for such cases. 1522 if (DeclRefExpr* DRL = dyn_cast<DeclRefExpr>(LeftExprSansParen)) 1523 if (DeclRefExpr* DRR = dyn_cast<DeclRefExpr>(RightExprSansParen)) 1524 if (DRL->getDecl() == DRR->getDecl()) 1525 EmitWarning = false; 1526 1527 1528 // Special case: check for comparisons against literals that can be exactly 1529 // represented by APFloat. In such cases, do not emit a warning. This 1530 // is a heuristic: often comparison against such literals are used to 1531 // detect if a value in a variable has not changed. This clearly can 1532 // lead to false negatives. 1533 if (EmitWarning) { 1534 if (FloatingLiteral* FLL = dyn_cast<FloatingLiteral>(LeftExprSansParen)) { 1535 if (FLL->isExact()) 1536 EmitWarning = false; 1537 } else 1538 if (FloatingLiteral* FLR = dyn_cast<FloatingLiteral>(RightExprSansParen)){ 1539 if (FLR->isExact()) 1540 EmitWarning = false; 1541 } 1542 } 1543 1544 // Check for comparisons with builtin types. 1545 if (EmitWarning) 1546 if (CallExpr* CL = dyn_cast<CallExpr>(LeftExprSansParen)) 1547 if (CL->isBuiltinCall(Context)) 1548 EmitWarning = false; 1549 1550 if (EmitWarning) 1551 if (CallExpr* CR = dyn_cast<CallExpr>(RightExprSansParen)) 1552 if (CR->isBuiltinCall(Context)) 1553 EmitWarning = false; 1554 1555 // Emit the diagnostic. 1556 if (EmitWarning) 1557 Diag(loc, diag::warn_floatingpoint_eq) 1558 << lex->getSourceRange() << rex->getSourceRange(); 1559} 1560 1561//===--- CHECK: Integer mixed-sign comparisons (-Wsign-compare) --------===// 1562//===--- CHECK: Lossy implicit conversions (-Wconversion) --------------===// 1563 1564namespace { 1565 1566/// Structure recording the 'active' range of an integer-valued 1567/// expression. 1568struct IntRange { 1569 /// The number of bits active in the int. 1570 unsigned Width; 1571 1572 /// True if the int is known not to have negative values. 1573 bool NonNegative; 1574 1575 IntRange() {} 1576 IntRange(unsigned Width, bool NonNegative) 1577 : Width(Width), NonNegative(NonNegative) 1578 {} 1579 1580 // Returns the range of the bool type. 1581 static IntRange forBoolType() { 1582 return IntRange(1, true); 1583 } 1584 1585 // Returns the range of an integral type. 1586 static IntRange forType(ASTContext &C, QualType T) { 1587 return forCanonicalType(C, T->getCanonicalTypeInternal().getTypePtr()); 1588 } 1589 1590 // Returns the range of an integeral type based on its canonical 1591 // representation. 1592 static IntRange forCanonicalType(ASTContext &C, const Type *T) { 1593 assert(T->isCanonicalUnqualified()); 1594 1595 if (const VectorType *VT = dyn_cast<VectorType>(T)) 1596 T = VT->getElementType().getTypePtr(); 1597 if (const ComplexType *CT = dyn_cast<ComplexType>(T)) 1598 T = CT->getElementType().getTypePtr(); 1599 if (const EnumType *ET = dyn_cast<EnumType>(T)) 1600 T = ET->getDecl()->getIntegerType().getTypePtr(); 1601 1602 const BuiltinType *BT = cast<BuiltinType>(T); 1603 assert(BT->isInteger()); 1604 1605 return IntRange(C.getIntWidth(QualType(T, 0)), BT->isUnsignedInteger()); 1606 } 1607 1608 // Returns the supremum of two ranges: i.e. their conservative merge. 1609 static IntRange join(const IntRange &L, const IntRange &R) { 1610 return IntRange(std::max(L.Width, R.Width), 1611 L.NonNegative && R.NonNegative); 1612 } 1613 1614 // Returns the infinum of two ranges: i.e. their aggressive merge. 1615 static IntRange meet(const IntRange &L, const IntRange &R) { 1616 return IntRange(std::min(L.Width, R.Width), 1617 L.NonNegative || R.NonNegative); 1618 } 1619}; 1620 1621IntRange GetValueRange(ASTContext &C, llvm::APSInt &value, unsigned MaxWidth) { 1622 if (value.isSigned() && value.isNegative()) 1623 return IntRange(value.getMinSignedBits(), false); 1624 1625 if (value.getBitWidth() > MaxWidth) 1626 value.trunc(MaxWidth); 1627 1628 // isNonNegative() just checks the sign bit without considering 1629 // signedness. 1630 return IntRange(value.getActiveBits(), true); 1631} 1632 1633IntRange GetValueRange(ASTContext &C, APValue &result, QualType Ty, 1634 unsigned MaxWidth) { 1635 if (result.isInt()) 1636 return GetValueRange(C, result.getInt(), MaxWidth); 1637 1638 if (result.isVector()) { 1639 IntRange R = GetValueRange(C, result.getVectorElt(0), Ty, MaxWidth); 1640 for (unsigned i = 1, e = result.getVectorLength(); i != e; ++i) { 1641 IntRange El = GetValueRange(C, result.getVectorElt(i), Ty, MaxWidth); 1642 R = IntRange::join(R, El); 1643 } 1644 return R; 1645 } 1646 1647 if (result.isComplexInt()) { 1648 IntRange R = GetValueRange(C, result.getComplexIntReal(), MaxWidth); 1649 IntRange I = GetValueRange(C, result.getComplexIntImag(), MaxWidth); 1650 return IntRange::join(R, I); 1651 } 1652 1653 // This can happen with lossless casts to intptr_t of "based" lvalues. 1654 // Assume it might use arbitrary bits. 1655 // FIXME: The only reason we need to pass the type in here is to get 1656 // the sign right on this one case. It would be nice if APValue 1657 // preserved this. 1658 assert(result.isLValue()); 1659 return IntRange(MaxWidth, Ty->isUnsignedIntegerType()); 1660} 1661 1662/// Pseudo-evaluate the given integer expression, estimating the 1663/// range of values it might take. 1664/// 1665/// \param MaxWidth - the width to which the value will be truncated 1666IntRange GetExprRange(ASTContext &C, Expr *E, unsigned MaxWidth) { 1667 E = E->IgnoreParens(); 1668 1669 // Try a full evaluation first. 1670 Expr::EvalResult result; 1671 if (E->Evaluate(result, C)) 1672 return GetValueRange(C, result.Val, E->getType(), MaxWidth); 1673 1674 // I think we only want to look through implicit casts here; if the 1675 // user has an explicit widening cast, we should treat the value as 1676 // being of the new, wider type. 1677 if (ImplicitCastExpr *CE = dyn_cast<ImplicitCastExpr>(E)) { 1678 if (CE->getCastKind() == CastExpr::CK_NoOp) 1679 return GetExprRange(C, CE->getSubExpr(), MaxWidth); 1680 1681 IntRange OutputTypeRange = IntRange::forType(C, CE->getType()); 1682 1683 bool isIntegerCast = (CE->getCastKind() == CastExpr::CK_IntegralCast); 1684 if (!isIntegerCast && CE->getCastKind() == CastExpr::CK_Unknown) 1685 isIntegerCast = CE->getSubExpr()->getType()->isIntegerType(); 1686 1687 // Assume that non-integer casts can span the full range of the type. 1688 if (!isIntegerCast) 1689 return OutputTypeRange; 1690 1691 IntRange SubRange 1692 = GetExprRange(C, CE->getSubExpr(), 1693 std::min(MaxWidth, OutputTypeRange.Width)); 1694 1695 // Bail out if the subexpr's range is as wide as the cast type. 1696 if (SubRange.Width >= OutputTypeRange.Width) 1697 return OutputTypeRange; 1698 1699 // Otherwise, we take the smaller width, and we're non-negative if 1700 // either the output type or the subexpr is. 1701 return IntRange(SubRange.Width, 1702 SubRange.NonNegative || OutputTypeRange.NonNegative); 1703 } 1704 1705 if (ConditionalOperator *CO = dyn_cast<ConditionalOperator>(E)) { 1706 // If we can fold the condition, just take that operand. 1707 bool CondResult; 1708 if (CO->getCond()->EvaluateAsBooleanCondition(CondResult, C)) 1709 return GetExprRange(C, CondResult ? CO->getTrueExpr() 1710 : CO->getFalseExpr(), 1711 MaxWidth); 1712 1713 // Otherwise, conservatively merge. 1714 IntRange L = GetExprRange(C, CO->getTrueExpr(), MaxWidth); 1715 IntRange R = GetExprRange(C, CO->getFalseExpr(), MaxWidth); 1716 return IntRange::join(L, R); 1717 } 1718 1719 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) { 1720 switch (BO->getOpcode()) { 1721 1722 // Boolean-valued operations are single-bit and positive. 1723 case BinaryOperator::LAnd: 1724 case BinaryOperator::LOr: 1725 case BinaryOperator::LT: 1726 case BinaryOperator::GT: 1727 case BinaryOperator::LE: 1728 case BinaryOperator::GE: 1729 case BinaryOperator::EQ: 1730 case BinaryOperator::NE: 1731 return IntRange::forBoolType(); 1732 1733 // Operations with opaque sources are black-listed. 1734 case BinaryOperator::PtrMemD: 1735 case BinaryOperator::PtrMemI: 1736 return IntRange::forType(C, E->getType()); 1737 1738 // Bitwise-and uses the *infinum* of the two source ranges. 1739 case BinaryOperator::And: 1740 return IntRange::meet(GetExprRange(C, BO->getLHS(), MaxWidth), 1741 GetExprRange(C, BO->getRHS(), MaxWidth)); 1742 1743 // Left shift gets black-listed based on a judgement call. 1744 case BinaryOperator::Shl: 1745 return IntRange::forType(C, E->getType()); 1746 1747 // Right shift by a constant can narrow its left argument. 1748 case BinaryOperator::Shr: { 1749 IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth); 1750 1751 // If the shift amount is a positive constant, drop the width by 1752 // that much. 1753 llvm::APSInt shift; 1754 if (BO->getRHS()->isIntegerConstantExpr(shift, C) && 1755 shift.isNonNegative()) { 1756 unsigned zext = shift.getZExtValue(); 1757 if (zext >= L.Width) 1758 L.Width = (L.NonNegative ? 0 : 1); 1759 else 1760 L.Width -= zext; 1761 } 1762 1763 return L; 1764 } 1765 1766 // Comma acts as its right operand. 1767 case BinaryOperator::Comma: 1768 return GetExprRange(C, BO->getRHS(), MaxWidth); 1769 1770 // Black-list pointer subtractions. 1771 case BinaryOperator::Sub: 1772 if (BO->getLHS()->getType()->isPointerType()) 1773 return IntRange::forType(C, E->getType()); 1774 // fallthrough 1775 1776 default: 1777 break; 1778 } 1779 1780 // Treat every other operator as if it were closed on the 1781 // narrowest type that encompasses both operands. 1782 IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth); 1783 IntRange R = GetExprRange(C, BO->getRHS(), MaxWidth); 1784 return IntRange::join(L, R); 1785 } 1786 1787 if (UnaryOperator *UO = dyn_cast<UnaryOperator>(E)) { 1788 switch (UO->getOpcode()) { 1789 // Boolean-valued operations are white-listed. 1790 case UnaryOperator::LNot: 1791 return IntRange::forBoolType(); 1792 1793 // Operations with opaque sources are black-listed. 1794 case UnaryOperator::Deref: 1795 case UnaryOperator::AddrOf: // should be impossible 1796 case UnaryOperator::OffsetOf: 1797 return IntRange::forType(C, E->getType()); 1798 1799 default: 1800 return GetExprRange(C, UO->getSubExpr(), MaxWidth); 1801 } 1802 } 1803 1804 FieldDecl *BitField = E->getBitField(); 1805 if (BitField) { 1806 llvm::APSInt BitWidthAP = BitField->getBitWidth()->EvaluateAsInt(C); 1807 unsigned BitWidth = BitWidthAP.getZExtValue(); 1808 1809 return IntRange(BitWidth, BitField->getType()->isUnsignedIntegerType()); 1810 } 1811 1812 return IntRange::forType(C, E->getType()); 1813} 1814 1815/// Checks whether the given value, which currently has the given 1816/// source semantics, has the same value when coerced through the 1817/// target semantics. 1818bool IsSameFloatAfterCast(const llvm::APFloat &value, 1819 const llvm::fltSemantics &Src, 1820 const llvm::fltSemantics &Tgt) { 1821 llvm::APFloat truncated = value; 1822 1823 bool ignored; 1824 truncated.convert(Src, llvm::APFloat::rmNearestTiesToEven, &ignored); 1825 truncated.convert(Tgt, llvm::APFloat::rmNearestTiesToEven, &ignored); 1826 1827 return truncated.bitwiseIsEqual(value); 1828} 1829 1830/// Checks whether the given value, which currently has the given 1831/// source semantics, has the same value when coerced through the 1832/// target semantics. 1833/// 1834/// The value might be a vector of floats (or a complex number). 1835bool IsSameFloatAfterCast(const APValue &value, 1836 const llvm::fltSemantics &Src, 1837 const llvm::fltSemantics &Tgt) { 1838 if (value.isFloat()) 1839 return IsSameFloatAfterCast(value.getFloat(), Src, Tgt); 1840 1841 if (value.isVector()) { 1842 for (unsigned i = 0, e = value.getVectorLength(); i != e; ++i) 1843 if (!IsSameFloatAfterCast(value.getVectorElt(i), Src, Tgt)) 1844 return false; 1845 return true; 1846 } 1847 1848 assert(value.isComplexFloat()); 1849 return (IsSameFloatAfterCast(value.getComplexFloatReal(), Src, Tgt) && 1850 IsSameFloatAfterCast(value.getComplexFloatImag(), Src, Tgt)); 1851} 1852 1853} // end anonymous namespace 1854 1855/// \brief Implements -Wsign-compare. 1856/// 1857/// \param lex the left-hand expression 1858/// \param rex the right-hand expression 1859/// \param OpLoc the location of the joining operator 1860/// \param Equality whether this is an "equality-like" join, which 1861/// suppresses the warning in some cases 1862void Sema::CheckSignCompare(Expr *lex, Expr *rex, SourceLocation OpLoc, 1863 const PartialDiagnostic &PD, bool Equality) { 1864 // Don't warn if we're in an unevaluated context. 1865 if (ExprEvalContexts.back().Context == Unevaluated) 1866 return; 1867 1868 // If either expression is value-dependent, don't warn. We'll get another 1869 // chance at instantiation time. 1870 if (lex->isValueDependent() || rex->isValueDependent()) 1871 return; 1872 1873 QualType lt = lex->getType(), rt = rex->getType(); 1874 1875 // Only warn if both operands are integral. 1876 if (!lt->isIntegerType() || !rt->isIntegerType()) 1877 return; 1878 1879 // In C, the width of a bitfield determines its type, and the 1880 // declared type only contributes the signedness. This duplicates 1881 // the work that will later be done by UsualUnaryConversions. 1882 // Eventually, this check will be reorganized in a way that avoids 1883 // this duplication. 1884 if (!getLangOptions().CPlusPlus) { 1885 QualType tmp; 1886 tmp = Context.isPromotableBitField(lex); 1887 if (!tmp.isNull()) lt = tmp; 1888 tmp = Context.isPromotableBitField(rex); 1889 if (!tmp.isNull()) rt = tmp; 1890 } 1891 1892 // The rule is that the signed operand becomes unsigned, so isolate the 1893 // signed operand. 1894 Expr *signedOperand = lex, *unsignedOperand = rex; 1895 QualType signedType = lt, unsignedType = rt; 1896 if (lt->isSignedIntegerType()) { 1897 if (rt->isSignedIntegerType()) return; 1898 } else { 1899 if (!rt->isSignedIntegerType()) return; 1900 std::swap(signedOperand, unsignedOperand); 1901 std::swap(signedType, unsignedType); 1902 } 1903 1904 unsigned unsignedWidth = Context.getIntWidth(unsignedType); 1905 unsigned signedWidth = Context.getIntWidth(signedType); 1906 1907 // If the unsigned type is strictly smaller than the signed type, 1908 // then (1) the result type will be signed and (2) the unsigned 1909 // value will fit fully within the signed type, and thus the result 1910 // of the comparison will be exact. 1911 if (signedWidth > unsignedWidth) 1912 return; 1913 1914 // Otherwise, calculate the effective ranges. 1915 IntRange signedRange = GetExprRange(Context, signedOperand, signedWidth); 1916 IntRange unsignedRange = GetExprRange(Context, unsignedOperand, unsignedWidth); 1917 1918 // We should never be unable to prove that the unsigned operand is 1919 // non-negative. 1920 assert(unsignedRange.NonNegative && "unsigned range includes negative?"); 1921 1922 // If the signed operand is non-negative, then the signed->unsigned 1923 // conversion won't change it. 1924 if (signedRange.NonNegative) 1925 return; 1926 1927 // For (in)equality comparisons, if the unsigned operand is a 1928 // constant which cannot collide with a overflowed signed operand, 1929 // then reinterpreting the signed operand as unsigned will not 1930 // change the result of the comparison. 1931 if (Equality && unsignedRange.Width < unsignedWidth) 1932 return; 1933 1934 Diag(OpLoc, PD) 1935 << lt << rt << lex->getSourceRange() << rex->getSourceRange(); 1936} 1937 1938/// Diagnose an implicit cast; purely a helper for CheckImplicitConversion. 1939static void DiagnoseImpCast(Sema &S, Expr *E, QualType T, unsigned diag) { 1940 S.Diag(E->getExprLoc(), diag) << E->getType() << T << E->getSourceRange(); 1941} 1942 1943/// Implements -Wconversion. 1944void Sema::CheckImplicitConversion(Expr *E, QualType T) { 1945 // Don't diagnose in unevaluated contexts. 1946 if (ExprEvalContexts.back().Context == Sema::Unevaluated) 1947 return; 1948 1949 // Don't diagnose for value-dependent expressions. 1950 if (E->isValueDependent()) 1951 return; 1952 1953 const Type *Source = Context.getCanonicalType(E->getType()).getTypePtr(); 1954 const Type *Target = Context.getCanonicalType(T).getTypePtr(); 1955 1956 // Never diagnose implicit casts to bool. 1957 if (Target->isSpecificBuiltinType(BuiltinType::Bool)) 1958 return; 1959 1960 // Strip vector types. 1961 if (isa<VectorType>(Source)) { 1962 if (!isa<VectorType>(Target)) 1963 return DiagnoseImpCast(*this, E, T, diag::warn_impcast_vector_scalar); 1964 1965 Source = cast<VectorType>(Source)->getElementType().getTypePtr(); 1966 Target = cast<VectorType>(Target)->getElementType().getTypePtr(); 1967 } 1968 1969 // Strip complex types. 1970 if (isa<ComplexType>(Source)) { 1971 if (!isa<ComplexType>(Target)) 1972 return DiagnoseImpCast(*this, E, T, diag::warn_impcast_complex_scalar); 1973 1974 Source = cast<ComplexType>(Source)->getElementType().getTypePtr(); 1975 Target = cast<ComplexType>(Target)->getElementType().getTypePtr(); 1976 } 1977 1978 const BuiltinType *SourceBT = dyn_cast<BuiltinType>(Source); 1979 const BuiltinType *TargetBT = dyn_cast<BuiltinType>(Target); 1980 1981 // If the source is floating point... 1982 if (SourceBT && SourceBT->isFloatingPoint()) { 1983 // ...and the target is floating point... 1984 if (TargetBT && TargetBT->isFloatingPoint()) { 1985 // ...then warn if we're dropping FP rank. 1986 1987 // Builtin FP kinds are ordered by increasing FP rank. 1988 if (SourceBT->getKind() > TargetBT->getKind()) { 1989 // Don't warn about float constants that are precisely 1990 // representable in the target type. 1991 Expr::EvalResult result; 1992 if (E->Evaluate(result, Context)) { 1993 // Value might be a float, a float vector, or a float complex. 1994 if (IsSameFloatAfterCast(result.Val, 1995 Context.getFloatTypeSemantics(QualType(TargetBT, 0)), 1996 Context.getFloatTypeSemantics(QualType(SourceBT, 0)))) 1997 return; 1998 } 1999 2000 DiagnoseImpCast(*this, E, T, diag::warn_impcast_float_precision); 2001 } 2002 return; 2003 } 2004 2005 // If the target is integral, always warn. 2006 if ((TargetBT && TargetBT->isInteger())) 2007 // TODO: don't warn for integer values? 2008 return DiagnoseImpCast(*this, E, T, diag::warn_impcast_float_integer); 2009 2010 return; 2011 } 2012 2013 if (!Source->isIntegerType() || !Target->isIntegerType()) 2014 return; 2015 2016 IntRange SourceRange = GetExprRange(Context, E, Context.getIntWidth(E->getType())); 2017 IntRange TargetRange = IntRange::forCanonicalType(Context, Target); 2018 2019 // FIXME: also signed<->unsigned? 2020 2021 if (SourceRange.Width > TargetRange.Width) { 2022 // People want to build with -Wshorten-64-to-32 and not -Wconversion 2023 // and by god we'll let them. 2024 if (SourceRange.Width == 64 && TargetRange.Width == 32) 2025 return DiagnoseImpCast(*this, E, T, diag::warn_impcast_integer_64_32); 2026 return DiagnoseImpCast(*this, E, T, diag::warn_impcast_integer_precision); 2027 } 2028 2029 return; 2030} 2031 2032