SemaChecking.cpp revision 1497bffe829d082dd1d1927dc80ea08dcf1fcb49
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/Analysis/CFG.h" 17#include "clang/Analysis/AnalysisContext.h" 18#include "clang/Analysis/Analyses/PrintfFormatString.h" 19#include "clang/AST/ASTContext.h" 20#include "clang/AST/CharUnits.h" 21#include "clang/AST/DeclObjC.h" 22#include "clang/AST/ExprCXX.h" 23#include "clang/AST/ExprObjC.h" 24#include "clang/AST/DeclObjC.h" 25#include "clang/AST/StmtCXX.h" 26#include "clang/AST/StmtObjC.h" 27#include "clang/Lex/LiteralSupport.h" 28#include "clang/Lex/Preprocessor.h" 29#include "llvm/ADT/BitVector.h" 30#include "llvm/ADT/STLExtras.h" 31#include <limits> 32#include <queue> 33using namespace clang; 34 35/// getLocationOfStringLiteralByte - Return a source location that points to the 36/// specified byte of the specified string literal. 37/// 38/// Strings are amazingly complex. They can be formed from multiple tokens and 39/// can have escape sequences in them in addition to the usual trigraph and 40/// escaped newline business. This routine handles this complexity. 41/// 42SourceLocation Sema::getLocationOfStringLiteralByte(const StringLiteral *SL, 43 unsigned ByteNo) const { 44 assert(!SL->isWide() && "This doesn't work for wide strings yet"); 45 46 // Loop over all of the tokens in this string until we find the one that 47 // contains the byte we're looking for. 48 unsigned TokNo = 0; 49 while (1) { 50 assert(TokNo < SL->getNumConcatenated() && "Invalid byte number!"); 51 SourceLocation StrTokLoc = SL->getStrTokenLoc(TokNo); 52 53 // Get the spelling of the string so that we can get the data that makes up 54 // the string literal, not the identifier for the macro it is potentially 55 // expanded through. 56 SourceLocation StrTokSpellingLoc = SourceMgr.getSpellingLoc(StrTokLoc); 57 58 // Re-lex the token to get its length and original spelling. 59 std::pair<FileID, unsigned> LocInfo = 60 SourceMgr.getDecomposedLoc(StrTokSpellingLoc); 61 std::pair<const char *,const char *> Buffer = 62 SourceMgr.getBufferData(LocInfo.first); 63 const char *StrData = Buffer.first+LocInfo.second; 64 65 // Create a langops struct and enable trigraphs. This is sufficient for 66 // relexing tokens. 67 LangOptions LangOpts; 68 LangOpts.Trigraphs = true; 69 70 // Create a lexer starting at the beginning of this token. 71 Lexer TheLexer(StrTokSpellingLoc, LangOpts, Buffer.first, StrData, 72 Buffer.second); 73 Token TheTok; 74 TheLexer.LexFromRawLexer(TheTok); 75 76 // Use the StringLiteralParser to compute the length of the string in bytes. 77 StringLiteralParser SLP(&TheTok, 1, PP); 78 unsigned TokNumBytes = SLP.GetStringLength(); 79 80 // If the byte is in this token, return the location of the byte. 81 if (ByteNo < TokNumBytes || 82 (ByteNo == TokNumBytes && TokNo == SL->getNumConcatenated())) { 83 unsigned Offset = 84 StringLiteralParser::getOffsetOfStringByte(TheTok, ByteNo, PP); 85 86 // Now that we know the offset of the token in the spelling, use the 87 // preprocessor to get the offset in the original source. 88 return PP.AdvanceToTokenCharacter(StrTokLoc, Offset); 89 } 90 91 // Move to the next string token. 92 ++TokNo; 93 ByteNo -= TokNumBytes; 94 } 95} 96 97/// CheckablePrintfAttr - does a function call have a "printf" attribute 98/// and arguments that merit checking? 99bool Sema::CheckablePrintfAttr(const FormatAttr *Format, CallExpr *TheCall) { 100 if (Format->getType() == "printf") return true; 101 if (Format->getType() == "printf0") { 102 // printf0 allows null "format" string; if so don't check format/args 103 unsigned format_idx = Format->getFormatIdx() - 1; 104 // Does the index refer to the implicit object argument? 105 if (isa<CXXMemberCallExpr>(TheCall)) { 106 if (format_idx == 0) 107 return false; 108 --format_idx; 109 } 110 if (format_idx < TheCall->getNumArgs()) { 111 Expr *Format = TheCall->getArg(format_idx)->IgnoreParenCasts(); 112 if (!Format->isNullPointerConstant(Context, Expr::NPC_ValueDependentIsNull)) 113 return true; 114 } 115 } 116 return false; 117} 118 119Action::OwningExprResult 120Sema::CheckBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) { 121 OwningExprResult TheCallResult(Owned(TheCall)); 122 123 switch (BuiltinID) { 124 case Builtin::BI__builtin___CFStringMakeConstantString: 125 assert(TheCall->getNumArgs() == 1 && 126 "Wrong # arguments to builtin CFStringMakeConstantString"); 127 if (CheckObjCString(TheCall->getArg(0))) 128 return ExprError(); 129 break; 130 case Builtin::BI__builtin_stdarg_start: 131 case Builtin::BI__builtin_va_start: 132 if (SemaBuiltinVAStart(TheCall)) 133 return ExprError(); 134 break; 135 case Builtin::BI__builtin_isgreater: 136 case Builtin::BI__builtin_isgreaterequal: 137 case Builtin::BI__builtin_isless: 138 case Builtin::BI__builtin_islessequal: 139 case Builtin::BI__builtin_islessgreater: 140 case Builtin::BI__builtin_isunordered: 141 if (SemaBuiltinUnorderedCompare(TheCall)) 142 return ExprError(); 143 break; 144 case Builtin::BI__builtin_isfinite: 145 case Builtin::BI__builtin_isinf: 146 case Builtin::BI__builtin_isinf_sign: 147 case Builtin::BI__builtin_isnan: 148 case Builtin::BI__builtin_isnormal: 149 if (SemaBuiltinUnaryFP(TheCall)) 150 return ExprError(); 151 break; 152 case Builtin::BI__builtin_return_address: 153 case Builtin::BI__builtin_frame_address: 154 if (SemaBuiltinStackAddress(TheCall)) 155 return ExprError(); 156 break; 157 case Builtin::BI__builtin_eh_return_data_regno: 158 if (SemaBuiltinEHReturnDataRegNo(TheCall)) 159 return ExprError(); 160 break; 161 case Builtin::BI__builtin_shufflevector: 162 return SemaBuiltinShuffleVector(TheCall); 163 // TheCall will be freed by the smart pointer here, but that's fine, since 164 // SemaBuiltinShuffleVector guts it, but then doesn't release it. 165 case Builtin::BI__builtin_prefetch: 166 if (SemaBuiltinPrefetch(TheCall)) 167 return ExprError(); 168 break; 169 case Builtin::BI__builtin_object_size: 170 if (SemaBuiltinObjectSize(TheCall)) 171 return ExprError(); 172 break; 173 case Builtin::BI__builtin_longjmp: 174 if (SemaBuiltinLongjmp(TheCall)) 175 return ExprError(); 176 break; 177 case Builtin::BI__sync_fetch_and_add: 178 case Builtin::BI__sync_fetch_and_sub: 179 case Builtin::BI__sync_fetch_and_or: 180 case Builtin::BI__sync_fetch_and_and: 181 case Builtin::BI__sync_fetch_and_xor: 182 case Builtin::BI__sync_fetch_and_nand: 183 case Builtin::BI__sync_add_and_fetch: 184 case Builtin::BI__sync_sub_and_fetch: 185 case Builtin::BI__sync_and_and_fetch: 186 case Builtin::BI__sync_or_and_fetch: 187 case Builtin::BI__sync_xor_and_fetch: 188 case Builtin::BI__sync_nand_and_fetch: 189 case Builtin::BI__sync_val_compare_and_swap: 190 case Builtin::BI__sync_bool_compare_and_swap: 191 case Builtin::BI__sync_lock_test_and_set: 192 case Builtin::BI__sync_lock_release: 193 if (SemaBuiltinAtomicOverloaded(TheCall)) 194 return ExprError(); 195 break; 196 } 197 198 return move(TheCallResult); 199} 200 201/// CheckFunctionCall - Check a direct function call for various correctness 202/// and safety properties not strictly enforced by the C type system. 203bool Sema::CheckFunctionCall(FunctionDecl *FDecl, CallExpr *TheCall) { 204 // Get the IdentifierInfo* for the called function. 205 IdentifierInfo *FnInfo = FDecl->getIdentifier(); 206 207 // None of the checks below are needed for functions that don't have 208 // simple names (e.g., C++ conversion functions). 209 if (!FnInfo) 210 return false; 211 212 // FIXME: This mechanism should be abstracted to be less fragile and 213 // more efficient. For example, just map function ids to custom 214 // handlers. 215 216 // Printf checking. 217 if (const FormatAttr *Format = FDecl->getAttr<FormatAttr>()) { 218 if (CheckablePrintfAttr(Format, TheCall)) { 219 bool HasVAListArg = Format->getFirstArg() == 0; 220 if (!HasVAListArg) { 221 if (const FunctionProtoType *Proto 222 = FDecl->getType()->getAs<FunctionProtoType>()) 223 HasVAListArg = !Proto->isVariadic(); 224 } 225 CheckPrintfArguments(TheCall, HasVAListArg, Format->getFormatIdx() - 1, 226 HasVAListArg ? 0 : Format->getFirstArg() - 1); 227 } 228 } 229 230 for (const NonNullAttr *NonNull = FDecl->getAttr<NonNullAttr>(); NonNull; 231 NonNull = NonNull->getNext<NonNullAttr>()) 232 CheckNonNullArguments(NonNull, TheCall); 233 234 return false; 235} 236 237bool Sema::CheckBlockCall(NamedDecl *NDecl, CallExpr *TheCall) { 238 // Printf checking. 239 const FormatAttr *Format = NDecl->getAttr<FormatAttr>(); 240 if (!Format) 241 return false; 242 243 const VarDecl *V = dyn_cast<VarDecl>(NDecl); 244 if (!V) 245 return false; 246 247 QualType Ty = V->getType(); 248 if (!Ty->isBlockPointerType()) 249 return false; 250 251 if (!CheckablePrintfAttr(Format, TheCall)) 252 return false; 253 254 bool HasVAListArg = Format->getFirstArg() == 0; 255 if (!HasVAListArg) { 256 const FunctionType *FT = 257 Ty->getAs<BlockPointerType>()->getPointeeType()->getAs<FunctionType>(); 258 if (const FunctionProtoType *Proto = dyn_cast<FunctionProtoType>(FT)) 259 HasVAListArg = !Proto->isVariadic(); 260 } 261 CheckPrintfArguments(TheCall, HasVAListArg, Format->getFormatIdx() - 1, 262 HasVAListArg ? 0 : Format->getFirstArg() - 1); 263 264 return false; 265} 266 267/// SemaBuiltinAtomicOverloaded - We have a call to a function like 268/// __sync_fetch_and_add, which is an overloaded function based on the pointer 269/// type of its first argument. The main ActOnCallExpr routines have already 270/// promoted the types of arguments because all of these calls are prototyped as 271/// void(...). 272/// 273/// This function goes through and does final semantic checking for these 274/// builtins, 275bool Sema::SemaBuiltinAtomicOverloaded(CallExpr *TheCall) { 276 DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts()); 277 FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl()); 278 279 // Ensure that we have at least one argument to do type inference from. 280 if (TheCall->getNumArgs() < 1) 281 return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args) 282 << 0 << TheCall->getCallee()->getSourceRange(); 283 284 // Inspect the first argument of the atomic builtin. This should always be 285 // a pointer type, whose element is an integral scalar or pointer type. 286 // Because it is a pointer type, we don't have to worry about any implicit 287 // casts here. 288 Expr *FirstArg = TheCall->getArg(0); 289 if (!FirstArg->getType()->isPointerType()) 290 return Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer) 291 << FirstArg->getType() << FirstArg->getSourceRange(); 292 293 QualType ValType = FirstArg->getType()->getAs<PointerType>()->getPointeeType(); 294 if (!ValType->isIntegerType() && !ValType->isPointerType() && 295 !ValType->isBlockPointerType()) 296 return Diag(DRE->getLocStart(), 297 diag::err_atomic_builtin_must_be_pointer_intptr) 298 << FirstArg->getType() << FirstArg->getSourceRange(); 299 300 // We need to figure out which concrete builtin this maps onto. For example, 301 // __sync_fetch_and_add with a 2 byte object turns into 302 // __sync_fetch_and_add_2. 303#define BUILTIN_ROW(x) \ 304 { Builtin::BI##x##_1, Builtin::BI##x##_2, Builtin::BI##x##_4, \ 305 Builtin::BI##x##_8, Builtin::BI##x##_16 } 306 307 static const unsigned BuiltinIndices[][5] = { 308 BUILTIN_ROW(__sync_fetch_and_add), 309 BUILTIN_ROW(__sync_fetch_and_sub), 310 BUILTIN_ROW(__sync_fetch_and_or), 311 BUILTIN_ROW(__sync_fetch_and_and), 312 BUILTIN_ROW(__sync_fetch_and_xor), 313 BUILTIN_ROW(__sync_fetch_and_nand), 314 315 BUILTIN_ROW(__sync_add_and_fetch), 316 BUILTIN_ROW(__sync_sub_and_fetch), 317 BUILTIN_ROW(__sync_and_and_fetch), 318 BUILTIN_ROW(__sync_or_and_fetch), 319 BUILTIN_ROW(__sync_xor_and_fetch), 320 BUILTIN_ROW(__sync_nand_and_fetch), 321 322 BUILTIN_ROW(__sync_val_compare_and_swap), 323 BUILTIN_ROW(__sync_bool_compare_and_swap), 324 BUILTIN_ROW(__sync_lock_test_and_set), 325 BUILTIN_ROW(__sync_lock_release) 326 }; 327#undef BUILTIN_ROW 328 329 // Determine the index of the size. 330 unsigned SizeIndex; 331 switch (Context.getTypeSizeInChars(ValType).getQuantity()) { 332 case 1: SizeIndex = 0; break; 333 case 2: SizeIndex = 1; break; 334 case 4: SizeIndex = 2; break; 335 case 8: SizeIndex = 3; break; 336 case 16: SizeIndex = 4; break; 337 default: 338 return Diag(DRE->getLocStart(), diag::err_atomic_builtin_pointer_size) 339 << FirstArg->getType() << FirstArg->getSourceRange(); 340 } 341 342 // Each of these builtins has one pointer argument, followed by some number of 343 // values (0, 1 or 2) followed by a potentially empty varags list of stuff 344 // that we ignore. Find out which row of BuiltinIndices to read from as well 345 // as the number of fixed args. 346 unsigned BuiltinID = FDecl->getBuiltinID(); 347 unsigned BuiltinIndex, NumFixed = 1; 348 switch (BuiltinID) { 349 default: assert(0 && "Unknown overloaded atomic builtin!"); 350 case Builtin::BI__sync_fetch_and_add: BuiltinIndex = 0; break; 351 case Builtin::BI__sync_fetch_and_sub: BuiltinIndex = 1; break; 352 case Builtin::BI__sync_fetch_and_or: BuiltinIndex = 2; break; 353 case Builtin::BI__sync_fetch_and_and: BuiltinIndex = 3; break; 354 case Builtin::BI__sync_fetch_and_xor: BuiltinIndex = 4; break; 355 case Builtin::BI__sync_fetch_and_nand:BuiltinIndex = 5; break; 356 357 case Builtin::BI__sync_add_and_fetch: BuiltinIndex = 6; break; 358 case Builtin::BI__sync_sub_and_fetch: BuiltinIndex = 7; break; 359 case Builtin::BI__sync_and_and_fetch: BuiltinIndex = 8; break; 360 case Builtin::BI__sync_or_and_fetch: BuiltinIndex = 9; break; 361 case Builtin::BI__sync_xor_and_fetch: BuiltinIndex =10; break; 362 case Builtin::BI__sync_nand_and_fetch:BuiltinIndex =11; break; 363 364 case Builtin::BI__sync_val_compare_and_swap: 365 BuiltinIndex = 12; 366 NumFixed = 2; 367 break; 368 case Builtin::BI__sync_bool_compare_and_swap: 369 BuiltinIndex = 13; 370 NumFixed = 2; 371 break; 372 case Builtin::BI__sync_lock_test_and_set: BuiltinIndex = 14; break; 373 case Builtin::BI__sync_lock_release: 374 BuiltinIndex = 15; 375 NumFixed = 0; 376 break; 377 } 378 379 // Now that we know how many fixed arguments we expect, first check that we 380 // have at least that many. 381 if (TheCall->getNumArgs() < 1+NumFixed) 382 return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args) 383 << 0 << TheCall->getCallee()->getSourceRange(); 384 385 386 // Get the decl for the concrete builtin from this, we can tell what the 387 // concrete integer type we should convert to is. 388 unsigned NewBuiltinID = BuiltinIndices[BuiltinIndex][SizeIndex]; 389 const char *NewBuiltinName = Context.BuiltinInfo.GetName(NewBuiltinID); 390 IdentifierInfo *NewBuiltinII = PP.getIdentifierInfo(NewBuiltinName); 391 FunctionDecl *NewBuiltinDecl = 392 cast<FunctionDecl>(LazilyCreateBuiltin(NewBuiltinII, NewBuiltinID, 393 TUScope, false, DRE->getLocStart())); 394 const FunctionProtoType *BuiltinFT = 395 NewBuiltinDecl->getType()->getAs<FunctionProtoType>(); 396 ValType = BuiltinFT->getArgType(0)->getAs<PointerType>()->getPointeeType(); 397 398 // If the first type needs to be converted (e.g. void** -> int*), do it now. 399 if (BuiltinFT->getArgType(0) != FirstArg->getType()) { 400 ImpCastExprToType(FirstArg, BuiltinFT->getArgType(0), CastExpr::CK_BitCast); 401 TheCall->setArg(0, FirstArg); 402 } 403 404 // Next, walk the valid ones promoting to the right type. 405 for (unsigned i = 0; i != NumFixed; ++i) { 406 Expr *Arg = TheCall->getArg(i+1); 407 408 // If the argument is an implicit cast, then there was a promotion due to 409 // "...", just remove it now. 410 if (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Arg)) { 411 Arg = ICE->getSubExpr(); 412 ICE->setSubExpr(0); 413 ICE->Destroy(Context); 414 TheCall->setArg(i+1, Arg); 415 } 416 417 // GCC does an implicit conversion to the pointer or integer ValType. This 418 // can fail in some cases (1i -> int**), check for this error case now. 419 CastExpr::CastKind Kind = CastExpr::CK_Unknown; 420 CXXMethodDecl *ConversionDecl = 0; 421 if (CheckCastTypes(Arg->getSourceRange(), ValType, Arg, Kind, 422 ConversionDecl)) 423 return true; 424 425 // Okay, we have something that *can* be converted to the right type. Check 426 // to see if there is a potentially weird extension going on here. This can 427 // happen when you do an atomic operation on something like an char* and 428 // pass in 42. The 42 gets converted to char. This is even more strange 429 // for things like 45.123 -> char, etc. 430 // FIXME: Do this check. 431 ImpCastExprToType(Arg, ValType, Kind, /*isLvalue=*/false); 432 TheCall->setArg(i+1, Arg); 433 } 434 435 // Switch the DeclRefExpr to refer to the new decl. 436 DRE->setDecl(NewBuiltinDecl); 437 DRE->setType(NewBuiltinDecl->getType()); 438 439 // Set the callee in the CallExpr. 440 // FIXME: This leaks the original parens and implicit casts. 441 Expr *PromotedCall = DRE; 442 UsualUnaryConversions(PromotedCall); 443 TheCall->setCallee(PromotedCall); 444 445 446 // Change the result type of the call to match the result type of the decl. 447 TheCall->setType(NewBuiltinDecl->getResultType()); 448 return false; 449} 450 451 452/// CheckObjCString - Checks that the argument to the builtin 453/// CFString constructor is correct 454/// FIXME: GCC currently emits the following warning: 455/// "warning: input conversion stopped due to an input byte that does not 456/// belong to the input codeset UTF-8" 457/// Note: It might also make sense to do the UTF-16 conversion here (would 458/// simplify the backend). 459bool Sema::CheckObjCString(Expr *Arg) { 460 Arg = Arg->IgnoreParenCasts(); 461 StringLiteral *Literal = dyn_cast<StringLiteral>(Arg); 462 463 if (!Literal || Literal->isWide()) { 464 Diag(Arg->getLocStart(), diag::err_cfstring_literal_not_string_constant) 465 << Arg->getSourceRange(); 466 return true; 467 } 468 469 const char *Data = Literal->getStrData(); 470 unsigned Length = Literal->getByteLength(); 471 472 for (unsigned i = 0; i < Length; ++i) { 473 if (!Data[i]) { 474 Diag(getLocationOfStringLiteralByte(Literal, i), 475 diag::warn_cfstring_literal_contains_nul_character) 476 << Arg->getSourceRange(); 477 break; 478 } 479 } 480 481 return false; 482} 483 484/// SemaBuiltinVAStart - Check the arguments to __builtin_va_start for validity. 485/// Emit an error and return true on failure, return false on success. 486bool Sema::SemaBuiltinVAStart(CallExpr *TheCall) { 487 Expr *Fn = TheCall->getCallee(); 488 if (TheCall->getNumArgs() > 2) { 489 Diag(TheCall->getArg(2)->getLocStart(), 490 diag::err_typecheck_call_too_many_args) 491 << 0 /*function call*/ << Fn->getSourceRange() 492 << SourceRange(TheCall->getArg(2)->getLocStart(), 493 (*(TheCall->arg_end()-1))->getLocEnd()); 494 return true; 495 } 496 497 if (TheCall->getNumArgs() < 2) { 498 return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args) 499 << 0 /*function call*/; 500 } 501 502 // Determine whether the current function is variadic or not. 503 bool isVariadic; 504 if (CurBlock) 505 isVariadic = CurBlock->isVariadic; 506 else if (getCurFunctionDecl()) { 507 if (FunctionProtoType* FTP = 508 dyn_cast<FunctionProtoType>(getCurFunctionDecl()->getType())) 509 isVariadic = FTP->isVariadic(); 510 else 511 isVariadic = false; 512 } else { 513 isVariadic = getCurMethodDecl()->isVariadic(); 514 } 515 516 if (!isVariadic) { 517 Diag(Fn->getLocStart(), diag::err_va_start_used_in_non_variadic_function); 518 return true; 519 } 520 521 // Verify that the second argument to the builtin is the last argument of the 522 // current function or method. 523 bool SecondArgIsLastNamedArgument = false; 524 const Expr *Arg = TheCall->getArg(1)->IgnoreParenCasts(); 525 526 if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Arg)) { 527 if (const ParmVarDecl *PV = dyn_cast<ParmVarDecl>(DR->getDecl())) { 528 // FIXME: This isn't correct for methods (results in bogus warning). 529 // Get the last formal in the current function. 530 const ParmVarDecl *LastArg; 531 if (CurBlock) 532 LastArg = *(CurBlock->TheDecl->param_end()-1); 533 else if (FunctionDecl *FD = getCurFunctionDecl()) 534 LastArg = *(FD->param_end()-1); 535 else 536 LastArg = *(getCurMethodDecl()->param_end()-1); 537 SecondArgIsLastNamedArgument = PV == LastArg; 538 } 539 } 540 541 if (!SecondArgIsLastNamedArgument) 542 Diag(TheCall->getArg(1)->getLocStart(), 543 diag::warn_second_parameter_of_va_start_not_last_named_argument); 544 return false; 545} 546 547/// SemaBuiltinUnorderedCompare - Handle functions like __builtin_isgreater and 548/// friends. This is declared to take (...), so we have to check everything. 549bool Sema::SemaBuiltinUnorderedCompare(CallExpr *TheCall) { 550 if (TheCall->getNumArgs() < 2) 551 return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args) 552 << 0 /*function call*/; 553 if (TheCall->getNumArgs() > 2) 554 return Diag(TheCall->getArg(2)->getLocStart(), 555 diag::err_typecheck_call_too_many_args) 556 << 0 /*function call*/ 557 << SourceRange(TheCall->getArg(2)->getLocStart(), 558 (*(TheCall->arg_end()-1))->getLocEnd()); 559 560 Expr *OrigArg0 = TheCall->getArg(0); 561 Expr *OrigArg1 = TheCall->getArg(1); 562 563 // Do standard promotions between the two arguments, returning their common 564 // type. 565 QualType Res = UsualArithmeticConversions(OrigArg0, OrigArg1, false); 566 567 // Make sure any conversions are pushed back into the call; this is 568 // type safe since unordered compare builtins are declared as "_Bool 569 // foo(...)". 570 TheCall->setArg(0, OrigArg0); 571 TheCall->setArg(1, OrigArg1); 572 573 if (OrigArg0->isTypeDependent() || OrigArg1->isTypeDependent()) 574 return false; 575 576 // If the common type isn't a real floating type, then the arguments were 577 // invalid for this operation. 578 if (!Res->isRealFloatingType()) 579 return Diag(OrigArg0->getLocStart(), 580 diag::err_typecheck_call_invalid_ordered_compare) 581 << OrigArg0->getType() << OrigArg1->getType() 582 << SourceRange(OrigArg0->getLocStart(), OrigArg1->getLocEnd()); 583 584 return false; 585} 586 587/// SemaBuiltinUnorderedCompare - Handle functions like __builtin_isnan and 588/// friends. This is declared to take (...), so we have to check everything. 589bool Sema::SemaBuiltinUnaryFP(CallExpr *TheCall) { 590 if (TheCall->getNumArgs() < 1) 591 return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args) 592 << 0 /*function call*/; 593 if (TheCall->getNumArgs() > 1) 594 return Diag(TheCall->getArg(1)->getLocStart(), 595 diag::err_typecheck_call_too_many_args) 596 << 0 /*function call*/ 597 << SourceRange(TheCall->getArg(1)->getLocStart(), 598 (*(TheCall->arg_end()-1))->getLocEnd()); 599 600 Expr *OrigArg = TheCall->getArg(0); 601 602 if (OrigArg->isTypeDependent()) 603 return false; 604 605 // This operation requires a floating-point number 606 if (!OrigArg->getType()->isRealFloatingType()) 607 return Diag(OrigArg->getLocStart(), 608 diag::err_typecheck_call_invalid_unary_fp) 609 << OrigArg->getType() << OrigArg->getSourceRange(); 610 611 return false; 612} 613 614bool Sema::SemaBuiltinStackAddress(CallExpr *TheCall) { 615 // The signature for these builtins is exact; the only thing we need 616 // to check is that the argument is a constant. 617 SourceLocation Loc; 618 if (!TheCall->getArg(0)->isTypeDependent() && 619 !TheCall->getArg(0)->isValueDependent() && 620 !TheCall->getArg(0)->isIntegerConstantExpr(Context, &Loc)) 621 return Diag(Loc, diag::err_stack_const_level) << TheCall->getSourceRange(); 622 623 return false; 624} 625 626/// SemaBuiltinShuffleVector - Handle __builtin_shufflevector. 627// This is declared to take (...), so we have to check everything. 628Action::OwningExprResult Sema::SemaBuiltinShuffleVector(CallExpr *TheCall) { 629 if (TheCall->getNumArgs() < 3) 630 return ExprError(Diag(TheCall->getLocEnd(), 631 diag::err_typecheck_call_too_few_args) 632 << 0 /*function call*/ << TheCall->getSourceRange()); 633 634 unsigned numElements = std::numeric_limits<unsigned>::max(); 635 if (!TheCall->getArg(0)->isTypeDependent() && 636 !TheCall->getArg(1)->isTypeDependent()) { 637 QualType FAType = TheCall->getArg(0)->getType(); 638 QualType SAType = TheCall->getArg(1)->getType(); 639 640 if (!FAType->isVectorType() || !SAType->isVectorType()) { 641 Diag(TheCall->getLocStart(), diag::err_shufflevector_non_vector) 642 << SourceRange(TheCall->getArg(0)->getLocStart(), 643 TheCall->getArg(1)->getLocEnd()); 644 return ExprError(); 645 } 646 647 if (!Context.hasSameUnqualifiedType(FAType, SAType)) { 648 Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector) 649 << SourceRange(TheCall->getArg(0)->getLocStart(), 650 TheCall->getArg(1)->getLocEnd()); 651 return ExprError(); 652 } 653 654 numElements = FAType->getAs<VectorType>()->getNumElements(); 655 if (TheCall->getNumArgs() != numElements+2) { 656 if (TheCall->getNumArgs() < numElements+2) 657 return ExprError(Diag(TheCall->getLocEnd(), 658 diag::err_typecheck_call_too_few_args) 659 << 0 /*function call*/ << TheCall->getSourceRange()); 660 return ExprError(Diag(TheCall->getLocEnd(), 661 diag::err_typecheck_call_too_many_args) 662 << 0 /*function call*/ << TheCall->getSourceRange()); 663 } 664 } 665 666 for (unsigned i = 2; i < TheCall->getNumArgs(); i++) { 667 if (TheCall->getArg(i)->isTypeDependent() || 668 TheCall->getArg(i)->isValueDependent()) 669 continue; 670 671 llvm::APSInt Result(32); 672 if (!TheCall->getArg(i)->isIntegerConstantExpr(Result, Context)) 673 return ExprError(Diag(TheCall->getLocStart(), 674 diag::err_shufflevector_nonconstant_argument) 675 << TheCall->getArg(i)->getSourceRange()); 676 677 if (Result.getActiveBits() > 64 || Result.getZExtValue() >= numElements*2) 678 return ExprError(Diag(TheCall->getLocStart(), 679 diag::err_shufflevector_argument_too_large) 680 << TheCall->getArg(i)->getSourceRange()); 681 } 682 683 llvm::SmallVector<Expr*, 32> exprs; 684 685 for (unsigned i = 0, e = TheCall->getNumArgs(); i != e; i++) { 686 exprs.push_back(TheCall->getArg(i)); 687 TheCall->setArg(i, 0); 688 } 689 690 return Owned(new (Context) ShuffleVectorExpr(Context, exprs.begin(), 691 exprs.size(), exprs[0]->getType(), 692 TheCall->getCallee()->getLocStart(), 693 TheCall->getRParenLoc())); 694} 695 696/// SemaBuiltinPrefetch - Handle __builtin_prefetch. 697// This is declared to take (const void*, ...) and can take two 698// optional constant int args. 699bool Sema::SemaBuiltinPrefetch(CallExpr *TheCall) { 700 unsigned NumArgs = TheCall->getNumArgs(); 701 702 if (NumArgs > 3) 703 return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_many_args) 704 << 0 /*function call*/ << TheCall->getSourceRange(); 705 706 // Argument 0 is checked for us and the remaining arguments must be 707 // constant integers. 708 for (unsigned i = 1; i != NumArgs; ++i) { 709 Expr *Arg = TheCall->getArg(i); 710 if (Arg->isTypeDependent()) 711 continue; 712 713 if (!Arg->getType()->isIntegralType()) 714 return Diag(TheCall->getLocStart(), diag::err_prefetch_invalid_arg_type) 715 << Arg->getSourceRange(); 716 717 ImpCastExprToType(Arg, Context.IntTy, CastExpr::CK_IntegralCast); 718 TheCall->setArg(i, Arg); 719 720 if (Arg->isValueDependent()) 721 continue; 722 723 llvm::APSInt Result; 724 if (!Arg->isIntegerConstantExpr(Result, Context)) 725 return Diag(TheCall->getLocStart(), diag::err_prefetch_invalid_arg_ice) 726 << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); 727 728 // FIXME: gcc issues a warning and rewrites these to 0. These 729 // seems especially odd for the third argument since the default 730 // is 3. 731 if (i == 1) { 732 if (Result.getLimitedValue() > 1) 733 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 734 << "0" << "1" << Arg->getSourceRange(); 735 } else { 736 if (Result.getLimitedValue() > 3) 737 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 738 << "0" << "3" << Arg->getSourceRange(); 739 } 740 } 741 742 return false; 743} 744 745/// SemaBuiltinEHReturnDataRegNo - Handle __builtin_eh_return_data_regno, the 746/// operand must be an integer constant. 747bool Sema::SemaBuiltinEHReturnDataRegNo(CallExpr *TheCall) { 748 llvm::APSInt Result; 749 if (!TheCall->getArg(0)->isIntegerConstantExpr(Result, Context)) 750 return Diag(TheCall->getLocStart(), diag::err_expr_not_ice) 751 << TheCall->getArg(0)->getSourceRange(); 752 753 return false; 754} 755 756 757/// SemaBuiltinObjectSize - Handle __builtin_object_size(void *ptr, 758/// int type). This simply type checks that type is one of the defined 759/// constants (0-3). 760// For compatability check 0-3, llvm only handles 0 and 2. 761bool Sema::SemaBuiltinObjectSize(CallExpr *TheCall) { 762 Expr *Arg = TheCall->getArg(1); 763 if (Arg->isTypeDependent()) 764 return false; 765 766 QualType ArgType = Arg->getType(); 767 const BuiltinType *BT = ArgType->getAs<BuiltinType>(); 768 llvm::APSInt Result(32); 769 if (!BT || BT->getKind() != BuiltinType::Int) 770 return Diag(TheCall->getLocStart(), diag::err_object_size_invalid_argument) 771 << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); 772 773 if (Arg->isValueDependent()) 774 return false; 775 776 if (!Arg->isIntegerConstantExpr(Result, Context)) { 777 return Diag(TheCall->getLocStart(), diag::err_object_size_invalid_argument) 778 << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); 779 } 780 781 if (Result.getSExtValue() < 0 || Result.getSExtValue() > 3) { 782 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 783 << "0" << "3" << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); 784 } 785 786 return false; 787} 788 789/// SemaBuiltinLongjmp - Handle __builtin_longjmp(void *env[5], int val). 790/// This checks that val is a constant 1. 791bool Sema::SemaBuiltinLongjmp(CallExpr *TheCall) { 792 Expr *Arg = TheCall->getArg(1); 793 if (Arg->isTypeDependent() || Arg->isValueDependent()) 794 return false; 795 796 llvm::APSInt Result(32); 797 if (!Arg->isIntegerConstantExpr(Result, Context) || Result != 1) 798 return Diag(TheCall->getLocStart(), diag::err_builtin_longjmp_invalid_val) 799 << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); 800 801 return false; 802} 803 804// Handle i > 1 ? "x" : "y", recursivelly 805bool Sema::SemaCheckStringLiteral(const Expr *E, const CallExpr *TheCall, 806 bool HasVAListArg, 807 unsigned format_idx, unsigned firstDataArg) { 808 if (E->isTypeDependent() || E->isValueDependent()) 809 return false; 810 811 switch (E->getStmtClass()) { 812 case Stmt::ConditionalOperatorClass: { 813 const ConditionalOperator *C = cast<ConditionalOperator>(E); 814 return SemaCheckStringLiteral(C->getTrueExpr(), TheCall, 815 HasVAListArg, format_idx, firstDataArg) 816 && SemaCheckStringLiteral(C->getRHS(), TheCall, 817 HasVAListArg, format_idx, firstDataArg); 818 } 819 820 case Stmt::ImplicitCastExprClass: { 821 const ImplicitCastExpr *Expr = cast<ImplicitCastExpr>(E); 822 return SemaCheckStringLiteral(Expr->getSubExpr(), TheCall, HasVAListArg, 823 format_idx, firstDataArg); 824 } 825 826 case Stmt::ParenExprClass: { 827 const ParenExpr *Expr = cast<ParenExpr>(E); 828 return SemaCheckStringLiteral(Expr->getSubExpr(), TheCall, HasVAListArg, 829 format_idx, firstDataArg); 830 } 831 832 case Stmt::DeclRefExprClass: { 833 const DeclRefExpr *DR = cast<DeclRefExpr>(E); 834 835 // As an exception, do not flag errors for variables binding to 836 // const string literals. 837 if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) { 838 bool isConstant = false; 839 QualType T = DR->getType(); 840 841 if (const ArrayType *AT = Context.getAsArrayType(T)) { 842 isConstant = AT->getElementType().isConstant(Context); 843 } else if (const PointerType *PT = T->getAs<PointerType>()) { 844 isConstant = T.isConstant(Context) && 845 PT->getPointeeType().isConstant(Context); 846 } 847 848 if (isConstant) { 849 if (const Expr *Init = VD->getAnyInitializer()) 850 return SemaCheckStringLiteral(Init, TheCall, 851 HasVAListArg, format_idx, firstDataArg); 852 } 853 854 // For vprintf* functions (i.e., HasVAListArg==true), we add a 855 // special check to see if the format string is a function parameter 856 // of the function calling the printf function. If the function 857 // has an attribute indicating it is a printf-like function, then we 858 // should suppress warnings concerning non-literals being used in a call 859 // to a vprintf function. For example: 860 // 861 // void 862 // logmessage(char const *fmt __attribute__ (format (printf, 1, 2)), ...){ 863 // va_list ap; 864 // va_start(ap, fmt); 865 // vprintf(fmt, ap); // Do NOT emit a warning about "fmt". 866 // ... 867 // 868 // 869 // FIXME: We don't have full attribute support yet, so just check to see 870 // if the argument is a DeclRefExpr that references a parameter. We'll 871 // add proper support for checking the attribute later. 872 if (HasVAListArg) 873 if (isa<ParmVarDecl>(VD)) 874 return true; 875 } 876 877 return false; 878 } 879 880 case Stmt::CallExprClass: { 881 const CallExpr *CE = cast<CallExpr>(E); 882 if (const ImplicitCastExpr *ICE 883 = dyn_cast<ImplicitCastExpr>(CE->getCallee())) { 884 if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(ICE->getSubExpr())) { 885 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(DRE->getDecl())) { 886 if (const FormatArgAttr *FA = FD->getAttr<FormatArgAttr>()) { 887 unsigned ArgIndex = FA->getFormatIdx(); 888 const Expr *Arg = CE->getArg(ArgIndex - 1); 889 890 return SemaCheckStringLiteral(Arg, TheCall, HasVAListArg, 891 format_idx, firstDataArg); 892 } 893 } 894 } 895 } 896 897 return false; 898 } 899 case Stmt::ObjCStringLiteralClass: 900 case Stmt::StringLiteralClass: { 901 const StringLiteral *StrE = NULL; 902 903 if (const ObjCStringLiteral *ObjCFExpr = dyn_cast<ObjCStringLiteral>(E)) 904 StrE = ObjCFExpr->getString(); 905 else 906 StrE = cast<StringLiteral>(E); 907 908 if (StrE) { 909 CheckPrintfString(StrE, E, TheCall, HasVAListArg, format_idx, 910 firstDataArg); 911 return true; 912 } 913 914 return false; 915 } 916 917 default: 918 return false; 919 } 920} 921 922void 923Sema::CheckNonNullArguments(const NonNullAttr *NonNull, 924 const CallExpr *TheCall) { 925 for (NonNullAttr::iterator i = NonNull->begin(), e = NonNull->end(); 926 i != e; ++i) { 927 const Expr *ArgExpr = TheCall->getArg(*i); 928 if (ArgExpr->isNullPointerConstant(Context, 929 Expr::NPC_ValueDependentIsNotNull)) 930 Diag(TheCall->getCallee()->getLocStart(), diag::warn_null_arg) 931 << ArgExpr->getSourceRange(); 932 } 933} 934 935/// CheckPrintfArguments - Check calls to printf (and similar functions) for 936/// correct use of format strings. 937/// 938/// HasVAListArg - A predicate indicating whether the printf-like 939/// function is passed an explicit va_arg argument (e.g., vprintf) 940/// 941/// format_idx - The index into Args for the format string. 942/// 943/// Improper format strings to functions in the printf family can be 944/// the source of bizarre bugs and very serious security holes. A 945/// good source of information is available in the following paper 946/// (which includes additional references): 947/// 948/// FormatGuard: Automatic Protection From printf Format String 949/// Vulnerabilities, Proceedings of the 10th USENIX Security Symposium, 2001. 950/// 951/// Functionality implemented: 952/// 953/// We can statically check the following properties for string 954/// literal format strings for non v.*printf functions (where the 955/// arguments are passed directly): 956// 957/// (1) Are the number of format conversions equal to the number of 958/// data arguments? 959/// 960/// (2) Does each format conversion correctly match the type of the 961/// corresponding data argument? (TODO) 962/// 963/// Moreover, for all printf functions we can: 964/// 965/// (3) Check for a missing format string (when not caught by type checking). 966/// 967/// (4) Check for no-operation flags; e.g. using "#" with format 968/// conversion 'c' (TODO) 969/// 970/// (5) Check the use of '%n', a major source of security holes. 971/// 972/// (6) Check for malformed format conversions that don't specify anything. 973/// 974/// (7) Check for empty format strings. e.g: printf(""); 975/// 976/// (8) Check that the format string is a wide literal. 977/// 978/// All of these checks can be done by parsing the format string. 979/// 980/// For now, we ONLY do (1), (3), (5), (6), (7), and (8). 981void 982Sema::CheckPrintfArguments(const CallExpr *TheCall, bool HasVAListArg, 983 unsigned format_idx, unsigned firstDataArg) { 984 const Expr *Fn = TheCall->getCallee(); 985 986 // The way the format attribute works in GCC, the implicit this argument 987 // of member functions is counted. However, it doesn't appear in our own 988 // lists, so decrement format_idx in that case. 989 if (isa<CXXMemberCallExpr>(TheCall)) { 990 // Catch a format attribute mistakenly referring to the object argument. 991 if (format_idx == 0) 992 return; 993 --format_idx; 994 if(firstDataArg != 0) 995 --firstDataArg; 996 } 997 998 // CHECK: printf-like function is called with no format string. 999 if (format_idx >= TheCall->getNumArgs()) { 1000 Diag(TheCall->getRParenLoc(), diag::warn_printf_missing_format_string) 1001 << Fn->getSourceRange(); 1002 return; 1003 } 1004 1005 const Expr *OrigFormatExpr = TheCall->getArg(format_idx)->IgnoreParenCasts(); 1006 1007 // CHECK: format string is not a string literal. 1008 // 1009 // Dynamically generated format strings are difficult to 1010 // automatically vet at compile time. Requiring that format strings 1011 // are string literals: (1) permits the checking of format strings by 1012 // the compiler and thereby (2) can practically remove the source of 1013 // many format string exploits. 1014 1015 // Format string can be either ObjC string (e.g. @"%d") or 1016 // C string (e.g. "%d") 1017 // ObjC string uses the same format specifiers as C string, so we can use 1018 // the same format string checking logic for both ObjC and C strings. 1019 if (SemaCheckStringLiteral(OrigFormatExpr, TheCall, HasVAListArg, format_idx, 1020 firstDataArg)) 1021 return; // Literal format string found, check done! 1022 1023 // If there are no arguments specified, warn with -Wformat-security, otherwise 1024 // warn only with -Wformat-nonliteral. 1025 if (TheCall->getNumArgs() == format_idx+1) 1026 Diag(TheCall->getArg(format_idx)->getLocStart(), 1027 diag::warn_printf_nonliteral_noargs) 1028 << OrigFormatExpr->getSourceRange(); 1029 else 1030 Diag(TheCall->getArg(format_idx)->getLocStart(), 1031 diag::warn_printf_nonliteral) 1032 << OrigFormatExpr->getSourceRange(); 1033} 1034 1035namespace { 1036class CheckPrintfHandler : public analyze_printf::FormatStringHandler { 1037 Sema &S; 1038 const StringLiteral *FExpr; 1039 const Expr *OrigFormatExpr; 1040 unsigned NumConversions; 1041 const unsigned NumDataArgs; 1042 const bool IsObjCLiteral; 1043 const char *Beg; // Start of format string. 1044 const bool HasVAListArg; 1045 const CallExpr *TheCall; 1046 unsigned FormatIdx; 1047public: 1048 CheckPrintfHandler(Sema &s, const StringLiteral *fexpr, 1049 const Expr *origFormatExpr, 1050 unsigned numDataArgs, bool isObjCLiteral, 1051 const char *beg, bool hasVAListArg, 1052 const CallExpr *theCall, unsigned formatIdx) 1053 : S(s), FExpr(fexpr), OrigFormatExpr(origFormatExpr), 1054 NumConversions(0), NumDataArgs(numDataArgs), 1055 IsObjCLiteral(isObjCLiteral), Beg(beg), 1056 HasVAListArg(hasVAListArg), 1057 TheCall(theCall), FormatIdx(formatIdx) {} 1058 1059 void DoneProcessing(); 1060 1061 void HandleIncompleteFormatSpecifier(const char *startSpecifier, 1062 unsigned specifierLen); 1063 1064 void 1065 HandleInvalidConversionSpecifier(const analyze_printf::FormatSpecifier &FS, 1066 const char *startSpecifier, 1067 unsigned specifierLen); 1068 1069 void HandleNullChar(const char *nullCharacter); 1070 1071 bool HandleFormatSpecifier(const analyze_printf::FormatSpecifier &FS, 1072 const char *startSpecifier, 1073 unsigned specifierLen); 1074private: 1075 SourceRange getFormatStringRange(); 1076 SourceRange getFormatSpecifierRange(const char *startSpecifier, 1077 unsigned specifierLen); 1078 SourceLocation getLocationOfByte(const char *x); 1079 1080 bool HandleAmount(const analyze_printf::OptionalAmount &Amt, 1081 unsigned MissingArgDiag, unsigned BadTypeDiag, 1082 const char *startSpecifier, unsigned specifierLen); 1083 void HandleFlags(const analyze_printf::FormatSpecifier &FS, 1084 llvm::StringRef flag, llvm::StringRef cspec, 1085 const char *startSpecifier, unsigned specifierLen); 1086 1087 bool MatchType(QualType A, QualType B, bool ignoreSign); 1088 1089 const Expr *getDataArg(unsigned i) const; 1090}; 1091} 1092 1093SourceRange CheckPrintfHandler::getFormatStringRange() { 1094 return OrigFormatExpr->getSourceRange(); 1095} 1096 1097SourceRange CheckPrintfHandler:: 1098getFormatSpecifierRange(const char *startSpecifier, unsigned specifierLen) { 1099 return SourceRange(getLocationOfByte(startSpecifier), 1100 getLocationOfByte(startSpecifier+specifierLen-1)); 1101} 1102 1103SourceLocation CheckPrintfHandler::getLocationOfByte(const char *x) { 1104 return S.getLocationOfStringLiteralByte(FExpr, x - Beg); 1105} 1106 1107void CheckPrintfHandler:: 1108HandleIncompleteFormatSpecifier(const char *startSpecifier, 1109 unsigned specifierLen) { 1110 SourceLocation Loc = getLocationOfByte(startSpecifier); 1111 S.Diag(Loc, diag::warn_printf_incomplete_specifier) 1112 << getFormatSpecifierRange(startSpecifier, specifierLen); 1113} 1114 1115void CheckPrintfHandler:: 1116HandleInvalidConversionSpecifier(const analyze_printf::FormatSpecifier &FS, 1117 const char *startSpecifier, 1118 unsigned specifierLen) { 1119 1120 ++NumConversions; 1121 const analyze_printf::ConversionSpecifier &CS = 1122 FS.getConversionSpecifier(); 1123 SourceLocation Loc = getLocationOfByte(CS.getStart()); 1124 S.Diag(Loc, diag::warn_printf_invalid_conversion) 1125 << llvm::StringRef(CS.getStart(), CS.getLength()) 1126 << getFormatSpecifierRange(startSpecifier, specifierLen); 1127} 1128 1129void CheckPrintfHandler::HandleNullChar(const char *nullCharacter) { 1130 // The presence of a null character is likely an error. 1131 S.Diag(getLocationOfByte(nullCharacter), 1132 diag::warn_printf_format_string_contains_null_char) 1133 << getFormatStringRange(); 1134} 1135 1136const Expr *CheckPrintfHandler::getDataArg(unsigned i) const { 1137 return TheCall->getArg(FormatIdx + i); 1138} 1139 1140bool CheckPrintfHandler::MatchType(QualType A, QualType B, bool ignoreSign) { 1141 A = S.Context.getCanonicalType(A).getUnqualifiedType(); 1142 B = S.Context.getCanonicalType(B).getUnqualifiedType(); 1143 1144 if (A == B) 1145 return true; 1146 1147 if (ignoreSign) { 1148 if (const BuiltinType *BT = B->getAs<BuiltinType>()) { 1149 switch (BT->getKind()) { 1150 default: 1151 return false; 1152 case BuiltinType::Char_S: 1153 case BuiltinType::SChar: 1154 return A == S.Context.UnsignedCharTy; 1155 case BuiltinType::Char_U: 1156 case BuiltinType::UChar: 1157 return A == S.Context.SignedCharTy; 1158 case BuiltinType::Short: 1159 return A == S.Context.UnsignedShortTy; 1160 case BuiltinType::UShort: 1161 return A == S.Context.ShortTy; 1162 case BuiltinType::Int: 1163 return A == S.Context.UnsignedIntTy; 1164 case BuiltinType::UInt: 1165 return A == S.Context.IntTy; 1166 case BuiltinType::Long: 1167 return A == S.Context.UnsignedLongTy; 1168 case BuiltinType::ULong: 1169 return A == S.Context.LongTy; 1170 case BuiltinType::LongLong: 1171 return A == S.Context.UnsignedLongLongTy; 1172 case BuiltinType::ULongLong: 1173 return A == S.Context.LongLongTy; 1174 } 1175 return A == B; 1176 } 1177 } 1178 return false; 1179} 1180 1181void CheckPrintfHandler::HandleFlags(const analyze_printf::FormatSpecifier &FS, 1182 llvm::StringRef flag, 1183 llvm::StringRef cspec, 1184 const char *startSpecifier, 1185 unsigned specifierLen) { 1186 const analyze_printf::ConversionSpecifier &CS = FS.getConversionSpecifier(); 1187 S.Diag(getLocationOfByte(CS.getStart()), diag::warn_printf_nonsensical_flag) 1188 << flag << cspec << getFormatSpecifierRange(startSpecifier, specifierLen); 1189} 1190 1191bool 1192CheckPrintfHandler::HandleAmount(const analyze_printf::OptionalAmount &Amt, 1193 unsigned MissingArgDiag, 1194 unsigned BadTypeDiag, 1195 const char *startSpecifier, 1196 unsigned specifierLen) { 1197 1198 if (Amt.hasDataArgument()) { 1199 ++NumConversions; 1200 if (!HasVAListArg) { 1201 if (NumConversions > NumDataArgs) { 1202 S.Diag(getLocationOfByte(Amt.getStart()), MissingArgDiag) 1203 << getFormatSpecifierRange(startSpecifier, specifierLen); 1204 // Don't do any more checking. We will just emit 1205 // spurious errors. 1206 return false; 1207 } 1208 1209 // Type check the data argument. It should be an 'int'. 1210 // Although not in conformance with C99, we also allow the argument to be 1211 // an 'unsigned int' as that is a reasonably safe case. GCC also 1212 // doesn't emit a warning for that case. 1213 const Expr *Arg = getDataArg(NumConversions); 1214 QualType T = Arg->getType(); 1215 if (!MatchType(T, S.Context.IntTy, true)) { 1216 S.Diag(getLocationOfByte(Amt.getStart()), BadTypeDiag) 1217 << S.Context.IntTy << T 1218 << getFormatSpecifierRange(startSpecifier, specifierLen) 1219 << Arg->getSourceRange(); 1220 // Don't do any more checking. We will just emit 1221 // spurious errors. 1222 return false; 1223 } 1224 } 1225 } 1226 return true; 1227} 1228 1229bool 1230CheckPrintfHandler::HandleFormatSpecifier(const analyze_printf::FormatSpecifier 1231 &FS, 1232 const char *startSpecifier, 1233 unsigned specifierLen) { 1234 1235 using namespace analyze_printf; 1236 const ConversionSpecifier &CS = FS.getConversionSpecifier(); 1237 1238 // First check if the field width, precision, and conversion specifier 1239 // have matching data arguments. 1240 if (!HandleAmount(FS.getFieldWidth(), 1241 diag::warn_printf_asterisk_width_missing_arg, 1242 diag::warn_printf_asterisk_width_wrong_type, 1243 startSpecifier, specifierLen)) { 1244 return false; 1245 } 1246 1247 if (!HandleAmount(FS.getPrecision(), 1248 diag::warn_printf_asterisk_precision_missing_arg, 1249 diag::warn_printf_asterisk_precision_wrong_type, 1250 startSpecifier, specifierLen)) { 1251 return false; 1252 } 1253 1254 // Check for using an Objective-C specific conversion specifier 1255 // in a non-ObjC literal. 1256 if (!IsObjCLiteral && CS.isObjCArg()) { 1257 HandleInvalidConversionSpecifier(FS, startSpecifier, specifierLen); 1258 1259 // Continue checking the other format specifiers. 1260 return true; 1261 } 1262 1263 if (!CS.consumesDataArgument()) { 1264 // FIXME: Technically specifying a precision or field width here 1265 // makes no sense. Worth issuing a warning at some point. 1266 return true; 1267 } 1268 1269 ++NumConversions; 1270 1271 // Are we using '%n'? Issue a warning about this being 1272 // a possible security issue. 1273 if (CS.getKind() == ConversionSpecifier::OutIntPtrArg) { 1274 S.Diag(getLocationOfByte(CS.getStart()), diag::warn_printf_write_back) 1275 << getFormatSpecifierRange(startSpecifier, specifierLen); 1276 // Continue checking the other format specifiers. 1277 return true; 1278 } 1279 1280 if (CS.getKind() == ConversionSpecifier::VoidPtrArg) { 1281 if (FS.getPrecision().getHowSpecified() != OptionalAmount::NotSpecified) 1282 S.Diag(getLocationOfByte(CS.getStart()), 1283 diag::warn_printf_nonsensical_precision) 1284 << CS.getCharacters() 1285 << getFormatSpecifierRange(startSpecifier, specifierLen); 1286 } 1287 if (CS.getKind() == ConversionSpecifier::VoidPtrArg || 1288 CS.getKind() == ConversionSpecifier::CStrArg) { 1289 // FIXME: Instead of using "0", "+", etc., eventually get them from 1290 // the FormatSpecifier. 1291 if (FS.hasLeadingZeros()) 1292 HandleFlags(FS, "0", CS.getCharacters(), startSpecifier, specifierLen); 1293 if (FS.hasPlusPrefix()) 1294 HandleFlags(FS, "+", CS.getCharacters(), startSpecifier, specifierLen); 1295 if (FS.hasSpacePrefix()) 1296 HandleFlags(FS, " ", CS.getCharacters(), startSpecifier, specifierLen); 1297 } 1298 1299 // The remaining checks depend on the data arguments. 1300 if (HasVAListArg) 1301 return true; 1302 1303 if (NumConversions > NumDataArgs) { 1304 S.Diag(getLocationOfByte(CS.getStart()), 1305 diag::warn_printf_insufficient_data_args) 1306 << getFormatSpecifierRange(startSpecifier, specifierLen); 1307 // Don't do any more checking. 1308 return false; 1309 } 1310 1311 // Now type check the data expression that matches the 1312 // format specifier. 1313 const Expr *Ex = getDataArg(NumConversions); 1314 const analyze_printf::ArgTypeResult &ATR = FS.getArgType(S.Context); 1315 1316 if (const QualType *T = ATR.getSpecificType()) { 1317 if (!MatchType(*T, Ex->getType(), true)) { 1318 // Check if we didn't match because of an implicit cast from a 'char' 1319 // or 'short' to an 'int'. This is done because printf is a varargs 1320 // function. 1321 if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Ex)) 1322 if (ICE->getType() == S.Context.IntTy) 1323 if (MatchType(*T, ICE->getSubExpr()->getType(), true)) 1324 return true; 1325 1326 S.Diag(getLocationOfByte(CS.getStart()), 1327 diag::warn_printf_conversion_argument_type_mismatch) 1328 << *T << Ex->getType() 1329 << getFormatSpecifierRange(startSpecifier, specifierLen) 1330 << Ex->getSourceRange(); 1331 } 1332 return true; 1333 } 1334 1335 return true; 1336} 1337 1338void CheckPrintfHandler::DoneProcessing() { 1339 // Does the number of data arguments exceed the number of 1340 // format conversions in the format string? 1341 if (!HasVAListArg && NumConversions < NumDataArgs) 1342 S.Diag(getDataArg(NumConversions+1)->getLocStart(), 1343 diag::warn_printf_too_many_data_args) 1344 << getFormatStringRange(); 1345} 1346 1347void Sema::CheckPrintfString(const StringLiteral *FExpr, 1348 const Expr *OrigFormatExpr, 1349 const CallExpr *TheCall, bool HasVAListArg, 1350 unsigned format_idx, unsigned firstDataArg) { 1351 1352 // CHECK: is the format string a wide literal? 1353 if (FExpr->isWide()) { 1354 Diag(FExpr->getLocStart(), 1355 diag::warn_printf_format_string_is_wide_literal) 1356 << OrigFormatExpr->getSourceRange(); 1357 return; 1358 } 1359 1360 // Str - The format string. NOTE: this is NOT null-terminated! 1361 const char *Str = FExpr->getStrData(); 1362 1363 // CHECK: empty format string? 1364 unsigned StrLen = FExpr->getByteLength(); 1365 1366 if (StrLen == 0) { 1367 Diag(FExpr->getLocStart(), diag::warn_printf_empty_format_string) 1368 << OrigFormatExpr->getSourceRange(); 1369 return; 1370 } 1371 1372 CheckPrintfHandler H(*this, FExpr, OrigFormatExpr, 1373 TheCall->getNumArgs() - firstDataArg, 1374 isa<ObjCStringLiteral>(OrigFormatExpr), Str, 1375 HasVAListArg, TheCall, format_idx); 1376 1377 if (!analyze_printf::ParseFormatString(H, Str, Str + StrLen)) 1378 H.DoneProcessing(); 1379} 1380 1381//===--- CHECK: Return Address of Stack Variable --------------------------===// 1382 1383static DeclRefExpr* EvalVal(Expr *E); 1384static DeclRefExpr* EvalAddr(Expr* E); 1385 1386/// CheckReturnStackAddr - Check if a return statement returns the address 1387/// of a stack variable. 1388void 1389Sema::CheckReturnStackAddr(Expr *RetValExp, QualType lhsType, 1390 SourceLocation ReturnLoc) { 1391 1392 // Perform checking for returned stack addresses. 1393 if (lhsType->isPointerType() || lhsType->isBlockPointerType()) { 1394 if (DeclRefExpr *DR = EvalAddr(RetValExp)) 1395 Diag(DR->getLocStart(), diag::warn_ret_stack_addr) 1396 << DR->getDecl()->getDeclName() << RetValExp->getSourceRange(); 1397 1398 // Skip over implicit cast expressions when checking for block expressions. 1399 RetValExp = RetValExp->IgnoreParenCasts(); 1400 1401 if (BlockExpr *C = dyn_cast<BlockExpr>(RetValExp)) 1402 if (C->hasBlockDeclRefExprs()) 1403 Diag(C->getLocStart(), diag::err_ret_local_block) 1404 << C->getSourceRange(); 1405 1406 if (AddrLabelExpr *ALE = dyn_cast<AddrLabelExpr>(RetValExp)) 1407 Diag(ALE->getLocStart(), diag::warn_ret_addr_label) 1408 << ALE->getSourceRange(); 1409 1410 } else if (lhsType->isReferenceType()) { 1411 // Perform checking for stack values returned by reference. 1412 // Check for a reference to the stack 1413 if (DeclRefExpr *DR = EvalVal(RetValExp)) 1414 Diag(DR->getLocStart(), diag::warn_ret_stack_ref) 1415 << DR->getDecl()->getDeclName() << RetValExp->getSourceRange(); 1416 } 1417} 1418 1419/// EvalAddr - EvalAddr and EvalVal are mutually recursive functions that 1420/// check if the expression in a return statement evaluates to an address 1421/// to a location on the stack. The recursion is used to traverse the 1422/// AST of the return expression, with recursion backtracking when we 1423/// encounter a subexpression that (1) clearly does not lead to the address 1424/// of a stack variable or (2) is something we cannot determine leads to 1425/// the address of a stack variable based on such local checking. 1426/// 1427/// EvalAddr processes expressions that are pointers that are used as 1428/// references (and not L-values). EvalVal handles all other values. 1429/// At the base case of the recursion is a check for a DeclRefExpr* in 1430/// the refers to a stack variable. 1431/// 1432/// This implementation handles: 1433/// 1434/// * pointer-to-pointer casts 1435/// * implicit conversions from array references to pointers 1436/// * taking the address of fields 1437/// * arbitrary interplay between "&" and "*" operators 1438/// * pointer arithmetic from an address of a stack variable 1439/// * taking the address of an array element where the array is on the stack 1440static DeclRefExpr* EvalAddr(Expr *E) { 1441 // We should only be called for evaluating pointer expressions. 1442 assert((E->getType()->isAnyPointerType() || 1443 E->getType()->isBlockPointerType() || 1444 E->getType()->isObjCQualifiedIdType()) && 1445 "EvalAddr only works on pointers"); 1446 1447 // Our "symbolic interpreter" is just a dispatch off the currently 1448 // viewed AST node. We then recursively traverse the AST by calling 1449 // EvalAddr and EvalVal appropriately. 1450 switch (E->getStmtClass()) { 1451 case Stmt::ParenExprClass: 1452 // Ignore parentheses. 1453 return EvalAddr(cast<ParenExpr>(E)->getSubExpr()); 1454 1455 case Stmt::UnaryOperatorClass: { 1456 // The only unary operator that make sense to handle here 1457 // is AddrOf. All others don't make sense as pointers. 1458 UnaryOperator *U = cast<UnaryOperator>(E); 1459 1460 if (U->getOpcode() == UnaryOperator::AddrOf) 1461 return EvalVal(U->getSubExpr()); 1462 else 1463 return NULL; 1464 } 1465 1466 case Stmt::BinaryOperatorClass: { 1467 // Handle pointer arithmetic. All other binary operators are not valid 1468 // in this context. 1469 BinaryOperator *B = cast<BinaryOperator>(E); 1470 BinaryOperator::Opcode op = B->getOpcode(); 1471 1472 if (op != BinaryOperator::Add && op != BinaryOperator::Sub) 1473 return NULL; 1474 1475 Expr *Base = B->getLHS(); 1476 1477 // Determine which argument is the real pointer base. It could be 1478 // the RHS argument instead of the LHS. 1479 if (!Base->getType()->isPointerType()) Base = B->getRHS(); 1480 1481 assert (Base->getType()->isPointerType()); 1482 return EvalAddr(Base); 1483 } 1484 1485 // For conditional operators we need to see if either the LHS or RHS are 1486 // valid DeclRefExpr*s. If one of them is valid, we return it. 1487 case Stmt::ConditionalOperatorClass: { 1488 ConditionalOperator *C = cast<ConditionalOperator>(E); 1489 1490 // Handle the GNU extension for missing LHS. 1491 if (Expr *lhsExpr = C->getLHS()) 1492 if (DeclRefExpr* LHS = EvalAddr(lhsExpr)) 1493 return LHS; 1494 1495 return EvalAddr(C->getRHS()); 1496 } 1497 1498 // For casts, we need to handle conversions from arrays to 1499 // pointer values, and pointer-to-pointer conversions. 1500 case Stmt::ImplicitCastExprClass: 1501 case Stmt::CStyleCastExprClass: 1502 case Stmt::CXXFunctionalCastExprClass: { 1503 Expr* SubExpr = cast<CastExpr>(E)->getSubExpr(); 1504 QualType T = SubExpr->getType(); 1505 1506 if (SubExpr->getType()->isPointerType() || 1507 SubExpr->getType()->isBlockPointerType() || 1508 SubExpr->getType()->isObjCQualifiedIdType()) 1509 return EvalAddr(SubExpr); 1510 else if (T->isArrayType()) 1511 return EvalVal(SubExpr); 1512 else 1513 return 0; 1514 } 1515 1516 // C++ casts. For dynamic casts, static casts, and const casts, we 1517 // are always converting from a pointer-to-pointer, so we just blow 1518 // through the cast. In the case the dynamic cast doesn't fail (and 1519 // return NULL), we take the conservative route and report cases 1520 // where we return the address of a stack variable. For Reinterpre 1521 // FIXME: The comment about is wrong; we're not always converting 1522 // from pointer to pointer. I'm guessing that this code should also 1523 // handle references to objects. 1524 case Stmt::CXXStaticCastExprClass: 1525 case Stmt::CXXDynamicCastExprClass: 1526 case Stmt::CXXConstCastExprClass: 1527 case Stmt::CXXReinterpretCastExprClass: { 1528 Expr *S = cast<CXXNamedCastExpr>(E)->getSubExpr(); 1529 if (S->getType()->isPointerType() || S->getType()->isBlockPointerType()) 1530 return EvalAddr(S); 1531 else 1532 return NULL; 1533 } 1534 1535 // Everything else: we simply don't reason about them. 1536 default: 1537 return NULL; 1538 } 1539} 1540 1541 1542/// EvalVal - This function is complements EvalAddr in the mutual recursion. 1543/// See the comments for EvalAddr for more details. 1544static DeclRefExpr* EvalVal(Expr *E) { 1545 1546 // We should only be called for evaluating non-pointer expressions, or 1547 // expressions with a pointer type that are not used as references but instead 1548 // are l-values (e.g., DeclRefExpr with a pointer type). 1549 1550 // Our "symbolic interpreter" is just a dispatch off the currently 1551 // viewed AST node. We then recursively traverse the AST by calling 1552 // EvalAddr and EvalVal appropriately. 1553 switch (E->getStmtClass()) { 1554 case Stmt::DeclRefExprClass: { 1555 // DeclRefExpr: the base case. When we hit a DeclRefExpr we are looking 1556 // at code that refers to a variable's name. We check if it has local 1557 // storage within the function, and if so, return the expression. 1558 DeclRefExpr *DR = cast<DeclRefExpr>(E); 1559 1560 if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl())) 1561 if (V->hasLocalStorage() && !V->getType()->isReferenceType()) return DR; 1562 1563 return NULL; 1564 } 1565 1566 case Stmt::ParenExprClass: 1567 // Ignore parentheses. 1568 return EvalVal(cast<ParenExpr>(E)->getSubExpr()); 1569 1570 case Stmt::UnaryOperatorClass: { 1571 // The only unary operator that make sense to handle here 1572 // is Deref. All others don't resolve to a "name." This includes 1573 // handling all sorts of rvalues passed to a unary operator. 1574 UnaryOperator *U = cast<UnaryOperator>(E); 1575 1576 if (U->getOpcode() == UnaryOperator::Deref) 1577 return EvalAddr(U->getSubExpr()); 1578 1579 return NULL; 1580 } 1581 1582 case Stmt::ArraySubscriptExprClass: { 1583 // Array subscripts are potential references to data on the stack. We 1584 // retrieve the DeclRefExpr* for the array variable if it indeed 1585 // has local storage. 1586 return EvalAddr(cast<ArraySubscriptExpr>(E)->getBase()); 1587 } 1588 1589 case Stmt::ConditionalOperatorClass: { 1590 // For conditional operators we need to see if either the LHS or RHS are 1591 // non-NULL DeclRefExpr's. If one is non-NULL, we return it. 1592 ConditionalOperator *C = cast<ConditionalOperator>(E); 1593 1594 // Handle the GNU extension for missing LHS. 1595 if (Expr *lhsExpr = C->getLHS()) 1596 if (DeclRefExpr *LHS = EvalVal(lhsExpr)) 1597 return LHS; 1598 1599 return EvalVal(C->getRHS()); 1600 } 1601 1602 // Accesses to members are potential references to data on the stack. 1603 case Stmt::MemberExprClass: { 1604 MemberExpr *M = cast<MemberExpr>(E); 1605 1606 // Check for indirect access. We only want direct field accesses. 1607 if (!M->isArrow()) 1608 return EvalVal(M->getBase()); 1609 else 1610 return NULL; 1611 } 1612 1613 // Everything else: we simply don't reason about them. 1614 default: 1615 return NULL; 1616 } 1617} 1618 1619//===--- CHECK: Floating-Point comparisons (-Wfloat-equal) ---------------===// 1620 1621/// Check for comparisons of floating point operands using != and ==. 1622/// Issue a warning if these are no self-comparisons, as they are not likely 1623/// to do what the programmer intended. 1624void Sema::CheckFloatComparison(SourceLocation loc, Expr* lex, Expr *rex) { 1625 bool EmitWarning = true; 1626 1627 Expr* LeftExprSansParen = lex->IgnoreParens(); 1628 Expr* RightExprSansParen = rex->IgnoreParens(); 1629 1630 // Special case: check for x == x (which is OK). 1631 // Do not emit warnings for such cases. 1632 if (DeclRefExpr* DRL = dyn_cast<DeclRefExpr>(LeftExprSansParen)) 1633 if (DeclRefExpr* DRR = dyn_cast<DeclRefExpr>(RightExprSansParen)) 1634 if (DRL->getDecl() == DRR->getDecl()) 1635 EmitWarning = false; 1636 1637 1638 // Special case: check for comparisons against literals that can be exactly 1639 // represented by APFloat. In such cases, do not emit a warning. This 1640 // is a heuristic: often comparison against such literals are used to 1641 // detect if a value in a variable has not changed. This clearly can 1642 // lead to false negatives. 1643 if (EmitWarning) { 1644 if (FloatingLiteral* FLL = dyn_cast<FloatingLiteral>(LeftExprSansParen)) { 1645 if (FLL->isExact()) 1646 EmitWarning = false; 1647 } else 1648 if (FloatingLiteral* FLR = dyn_cast<FloatingLiteral>(RightExprSansParen)){ 1649 if (FLR->isExact()) 1650 EmitWarning = false; 1651 } 1652 } 1653 1654 // Check for comparisons with builtin types. 1655 if (EmitWarning) 1656 if (CallExpr* CL = dyn_cast<CallExpr>(LeftExprSansParen)) 1657 if (CL->isBuiltinCall(Context)) 1658 EmitWarning = false; 1659 1660 if (EmitWarning) 1661 if (CallExpr* CR = dyn_cast<CallExpr>(RightExprSansParen)) 1662 if (CR->isBuiltinCall(Context)) 1663 EmitWarning = false; 1664 1665 // Emit the diagnostic. 1666 if (EmitWarning) 1667 Diag(loc, diag::warn_floatingpoint_eq) 1668 << lex->getSourceRange() << rex->getSourceRange(); 1669} 1670 1671//===--- CHECK: Integer mixed-sign comparisons (-Wsign-compare) --------===// 1672//===--- CHECK: Lossy implicit conversions (-Wconversion) --------------===// 1673 1674namespace { 1675 1676/// Structure recording the 'active' range of an integer-valued 1677/// expression. 1678struct IntRange { 1679 /// The number of bits active in the int. 1680 unsigned Width; 1681 1682 /// True if the int is known not to have negative values. 1683 bool NonNegative; 1684 1685 IntRange() {} 1686 IntRange(unsigned Width, bool NonNegative) 1687 : Width(Width), NonNegative(NonNegative) 1688 {} 1689 1690 // Returns the range of the bool type. 1691 static IntRange forBoolType() { 1692 return IntRange(1, true); 1693 } 1694 1695 // Returns the range of an integral type. 1696 static IntRange forType(ASTContext &C, QualType T) { 1697 return forCanonicalType(C, T->getCanonicalTypeInternal().getTypePtr()); 1698 } 1699 1700 // Returns the range of an integeral type based on its canonical 1701 // representation. 1702 static IntRange forCanonicalType(ASTContext &C, const Type *T) { 1703 assert(T->isCanonicalUnqualified()); 1704 1705 if (const VectorType *VT = dyn_cast<VectorType>(T)) 1706 T = VT->getElementType().getTypePtr(); 1707 if (const ComplexType *CT = dyn_cast<ComplexType>(T)) 1708 T = CT->getElementType().getTypePtr(); 1709 if (const EnumType *ET = dyn_cast<EnumType>(T)) 1710 T = ET->getDecl()->getIntegerType().getTypePtr(); 1711 1712 const BuiltinType *BT = cast<BuiltinType>(T); 1713 assert(BT->isInteger()); 1714 1715 return IntRange(C.getIntWidth(QualType(T, 0)), BT->isUnsignedInteger()); 1716 } 1717 1718 // Returns the supremum of two ranges: i.e. their conservative merge. 1719 static IntRange join(const IntRange &L, const IntRange &R) { 1720 return IntRange(std::max(L.Width, R.Width), 1721 L.NonNegative && R.NonNegative); 1722 } 1723 1724 // Returns the infinum of two ranges: i.e. their aggressive merge. 1725 static IntRange meet(const IntRange &L, const IntRange &R) { 1726 return IntRange(std::min(L.Width, R.Width), 1727 L.NonNegative || R.NonNegative); 1728 } 1729}; 1730 1731IntRange GetValueRange(ASTContext &C, llvm::APSInt &value, unsigned MaxWidth) { 1732 if (value.isSigned() && value.isNegative()) 1733 return IntRange(value.getMinSignedBits(), false); 1734 1735 if (value.getBitWidth() > MaxWidth) 1736 value.trunc(MaxWidth); 1737 1738 // isNonNegative() just checks the sign bit without considering 1739 // signedness. 1740 return IntRange(value.getActiveBits(), true); 1741} 1742 1743IntRange GetValueRange(ASTContext &C, APValue &result, QualType Ty, 1744 unsigned MaxWidth) { 1745 if (result.isInt()) 1746 return GetValueRange(C, result.getInt(), MaxWidth); 1747 1748 if (result.isVector()) { 1749 IntRange R = GetValueRange(C, result.getVectorElt(0), Ty, MaxWidth); 1750 for (unsigned i = 1, e = result.getVectorLength(); i != e; ++i) { 1751 IntRange El = GetValueRange(C, result.getVectorElt(i), Ty, MaxWidth); 1752 R = IntRange::join(R, El); 1753 } 1754 return R; 1755 } 1756 1757 if (result.isComplexInt()) { 1758 IntRange R = GetValueRange(C, result.getComplexIntReal(), MaxWidth); 1759 IntRange I = GetValueRange(C, result.getComplexIntImag(), MaxWidth); 1760 return IntRange::join(R, I); 1761 } 1762 1763 // This can happen with lossless casts to intptr_t of "based" lvalues. 1764 // Assume it might use arbitrary bits. 1765 // FIXME: The only reason we need to pass the type in here is to get 1766 // the sign right on this one case. It would be nice if APValue 1767 // preserved this. 1768 assert(result.isLValue()); 1769 return IntRange(MaxWidth, Ty->isUnsignedIntegerType()); 1770} 1771 1772/// Pseudo-evaluate the given integer expression, estimating the 1773/// range of values it might take. 1774/// 1775/// \param MaxWidth - the width to which the value will be truncated 1776IntRange GetExprRange(ASTContext &C, Expr *E, unsigned MaxWidth) { 1777 E = E->IgnoreParens(); 1778 1779 // Try a full evaluation first. 1780 Expr::EvalResult result; 1781 if (E->Evaluate(result, C)) 1782 return GetValueRange(C, result.Val, E->getType(), MaxWidth); 1783 1784 // I think we only want to look through implicit casts here; if the 1785 // user has an explicit widening cast, we should treat the value as 1786 // being of the new, wider type. 1787 if (ImplicitCastExpr *CE = dyn_cast<ImplicitCastExpr>(E)) { 1788 if (CE->getCastKind() == CastExpr::CK_NoOp) 1789 return GetExprRange(C, CE->getSubExpr(), MaxWidth); 1790 1791 IntRange OutputTypeRange = IntRange::forType(C, CE->getType()); 1792 1793 bool isIntegerCast = (CE->getCastKind() == CastExpr::CK_IntegralCast); 1794 if (!isIntegerCast && CE->getCastKind() == CastExpr::CK_Unknown) 1795 isIntegerCast = CE->getSubExpr()->getType()->isIntegerType(); 1796 1797 // Assume that non-integer casts can span the full range of the type. 1798 if (!isIntegerCast) 1799 return OutputTypeRange; 1800 1801 IntRange SubRange 1802 = GetExprRange(C, CE->getSubExpr(), 1803 std::min(MaxWidth, OutputTypeRange.Width)); 1804 1805 // Bail out if the subexpr's range is as wide as the cast type. 1806 if (SubRange.Width >= OutputTypeRange.Width) 1807 return OutputTypeRange; 1808 1809 // Otherwise, we take the smaller width, and we're non-negative if 1810 // either the output type or the subexpr is. 1811 return IntRange(SubRange.Width, 1812 SubRange.NonNegative || OutputTypeRange.NonNegative); 1813 } 1814 1815 if (ConditionalOperator *CO = dyn_cast<ConditionalOperator>(E)) { 1816 // If we can fold the condition, just take that operand. 1817 bool CondResult; 1818 if (CO->getCond()->EvaluateAsBooleanCondition(CondResult, C)) 1819 return GetExprRange(C, CondResult ? CO->getTrueExpr() 1820 : CO->getFalseExpr(), 1821 MaxWidth); 1822 1823 // Otherwise, conservatively merge. 1824 IntRange L = GetExprRange(C, CO->getTrueExpr(), MaxWidth); 1825 IntRange R = GetExprRange(C, CO->getFalseExpr(), MaxWidth); 1826 return IntRange::join(L, R); 1827 } 1828 1829 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) { 1830 switch (BO->getOpcode()) { 1831 1832 // Boolean-valued operations are single-bit and positive. 1833 case BinaryOperator::LAnd: 1834 case BinaryOperator::LOr: 1835 case BinaryOperator::LT: 1836 case BinaryOperator::GT: 1837 case BinaryOperator::LE: 1838 case BinaryOperator::GE: 1839 case BinaryOperator::EQ: 1840 case BinaryOperator::NE: 1841 return IntRange::forBoolType(); 1842 1843 // Operations with opaque sources are black-listed. 1844 case BinaryOperator::PtrMemD: 1845 case BinaryOperator::PtrMemI: 1846 return IntRange::forType(C, E->getType()); 1847 1848 // Bitwise-and uses the *infinum* of the two source ranges. 1849 case BinaryOperator::And: 1850 return IntRange::meet(GetExprRange(C, BO->getLHS(), MaxWidth), 1851 GetExprRange(C, BO->getRHS(), MaxWidth)); 1852 1853 // Left shift gets black-listed based on a judgement call. 1854 case BinaryOperator::Shl: 1855 return IntRange::forType(C, E->getType()); 1856 1857 // Right shift by a constant can narrow its left argument. 1858 case BinaryOperator::Shr: { 1859 IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth); 1860 1861 // If the shift amount is a positive constant, drop the width by 1862 // that much. 1863 llvm::APSInt shift; 1864 if (BO->getRHS()->isIntegerConstantExpr(shift, C) && 1865 shift.isNonNegative()) { 1866 unsigned zext = shift.getZExtValue(); 1867 if (zext >= L.Width) 1868 L.Width = (L.NonNegative ? 0 : 1); 1869 else 1870 L.Width -= zext; 1871 } 1872 1873 return L; 1874 } 1875 1876 // Comma acts as its right operand. 1877 case BinaryOperator::Comma: 1878 return GetExprRange(C, BO->getRHS(), MaxWidth); 1879 1880 // Black-list pointer subtractions. 1881 case BinaryOperator::Sub: 1882 if (BO->getLHS()->getType()->isPointerType()) 1883 return IntRange::forType(C, E->getType()); 1884 // fallthrough 1885 1886 default: 1887 break; 1888 } 1889 1890 // Treat every other operator as if it were closed on the 1891 // narrowest type that encompasses both operands. 1892 IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth); 1893 IntRange R = GetExprRange(C, BO->getRHS(), MaxWidth); 1894 return IntRange::join(L, R); 1895 } 1896 1897 if (UnaryOperator *UO = dyn_cast<UnaryOperator>(E)) { 1898 switch (UO->getOpcode()) { 1899 // Boolean-valued operations are white-listed. 1900 case UnaryOperator::LNot: 1901 return IntRange::forBoolType(); 1902 1903 // Operations with opaque sources are black-listed. 1904 case UnaryOperator::Deref: 1905 case UnaryOperator::AddrOf: // should be impossible 1906 case UnaryOperator::OffsetOf: 1907 return IntRange::forType(C, E->getType()); 1908 1909 default: 1910 return GetExprRange(C, UO->getSubExpr(), MaxWidth); 1911 } 1912 } 1913 1914 FieldDecl *BitField = E->getBitField(); 1915 if (BitField) { 1916 llvm::APSInt BitWidthAP = BitField->getBitWidth()->EvaluateAsInt(C); 1917 unsigned BitWidth = BitWidthAP.getZExtValue(); 1918 1919 return IntRange(BitWidth, BitField->getType()->isUnsignedIntegerType()); 1920 } 1921 1922 return IntRange::forType(C, E->getType()); 1923} 1924 1925/// Checks whether the given value, which currently has the given 1926/// source semantics, has the same value when coerced through the 1927/// target semantics. 1928bool IsSameFloatAfterCast(const llvm::APFloat &value, 1929 const llvm::fltSemantics &Src, 1930 const llvm::fltSemantics &Tgt) { 1931 llvm::APFloat truncated = value; 1932 1933 bool ignored; 1934 truncated.convert(Src, llvm::APFloat::rmNearestTiesToEven, &ignored); 1935 truncated.convert(Tgt, llvm::APFloat::rmNearestTiesToEven, &ignored); 1936 1937 return truncated.bitwiseIsEqual(value); 1938} 1939 1940/// Checks whether the given value, which currently has the given 1941/// source semantics, has the same value when coerced through the 1942/// target semantics. 1943/// 1944/// The value might be a vector of floats (or a complex number). 1945bool IsSameFloatAfterCast(const APValue &value, 1946 const llvm::fltSemantics &Src, 1947 const llvm::fltSemantics &Tgt) { 1948 if (value.isFloat()) 1949 return IsSameFloatAfterCast(value.getFloat(), Src, Tgt); 1950 1951 if (value.isVector()) { 1952 for (unsigned i = 0, e = value.getVectorLength(); i != e; ++i) 1953 if (!IsSameFloatAfterCast(value.getVectorElt(i), Src, Tgt)) 1954 return false; 1955 return true; 1956 } 1957 1958 assert(value.isComplexFloat()); 1959 return (IsSameFloatAfterCast(value.getComplexFloatReal(), Src, Tgt) && 1960 IsSameFloatAfterCast(value.getComplexFloatImag(), Src, Tgt)); 1961} 1962 1963} // end anonymous namespace 1964 1965/// \brief Implements -Wsign-compare. 1966/// 1967/// \param lex the left-hand expression 1968/// \param rex the right-hand expression 1969/// \param OpLoc the location of the joining operator 1970/// \param Equality whether this is an "equality-like" join, which 1971/// suppresses the warning in some cases 1972void Sema::CheckSignCompare(Expr *lex, Expr *rex, SourceLocation OpLoc, 1973 const PartialDiagnostic &PD, bool Equality) { 1974 // Don't warn if we're in an unevaluated context. 1975 if (ExprEvalContexts.back().Context == Unevaluated) 1976 return; 1977 1978 // If either expression is value-dependent, don't warn. We'll get another 1979 // chance at instantiation time. 1980 if (lex->isValueDependent() || rex->isValueDependent()) 1981 return; 1982 1983 QualType lt = lex->getType(), rt = rex->getType(); 1984 1985 // Only warn if both operands are integral. 1986 if (!lt->isIntegerType() || !rt->isIntegerType()) 1987 return; 1988 1989 // In C, the width of a bitfield determines its type, and the 1990 // declared type only contributes the signedness. This duplicates 1991 // the work that will later be done by UsualUnaryConversions. 1992 // Eventually, this check will be reorganized in a way that avoids 1993 // this duplication. 1994 if (!getLangOptions().CPlusPlus) { 1995 QualType tmp; 1996 tmp = Context.isPromotableBitField(lex); 1997 if (!tmp.isNull()) lt = tmp; 1998 tmp = Context.isPromotableBitField(rex); 1999 if (!tmp.isNull()) rt = tmp; 2000 } 2001 2002 // The rule is that the signed operand becomes unsigned, so isolate the 2003 // signed operand. 2004 Expr *signedOperand = lex, *unsignedOperand = rex; 2005 QualType signedType = lt, unsignedType = rt; 2006 if (lt->isSignedIntegerType()) { 2007 if (rt->isSignedIntegerType()) return; 2008 } else { 2009 if (!rt->isSignedIntegerType()) return; 2010 std::swap(signedOperand, unsignedOperand); 2011 std::swap(signedType, unsignedType); 2012 } 2013 2014 unsigned unsignedWidth = Context.getIntWidth(unsignedType); 2015 unsigned signedWidth = Context.getIntWidth(signedType); 2016 2017 // If the unsigned type is strictly smaller than the signed type, 2018 // then (1) the result type will be signed and (2) the unsigned 2019 // value will fit fully within the signed type, and thus the result 2020 // of the comparison will be exact. 2021 if (signedWidth > unsignedWidth) 2022 return; 2023 2024 // Otherwise, calculate the effective ranges. 2025 IntRange signedRange = GetExprRange(Context, signedOperand, signedWidth); 2026 IntRange unsignedRange = GetExprRange(Context, unsignedOperand, unsignedWidth); 2027 2028 // We should never be unable to prove that the unsigned operand is 2029 // non-negative. 2030 assert(unsignedRange.NonNegative && "unsigned range includes negative?"); 2031 2032 // If the signed operand is non-negative, then the signed->unsigned 2033 // conversion won't change it. 2034 if (signedRange.NonNegative) 2035 return; 2036 2037 // For (in)equality comparisons, if the unsigned operand is a 2038 // constant which cannot collide with a overflowed signed operand, 2039 // then reinterpreting the signed operand as unsigned will not 2040 // change the result of the comparison. 2041 if (Equality && unsignedRange.Width < unsignedWidth) 2042 return; 2043 2044 Diag(OpLoc, PD) 2045 << lt << rt << lex->getSourceRange() << rex->getSourceRange(); 2046} 2047 2048/// Diagnose an implicit cast; purely a helper for CheckImplicitConversion. 2049static void DiagnoseImpCast(Sema &S, Expr *E, QualType T, unsigned diag) { 2050 S.Diag(E->getExprLoc(), diag) << E->getType() << T << E->getSourceRange(); 2051} 2052 2053/// Implements -Wconversion. 2054void Sema::CheckImplicitConversion(Expr *E, QualType T) { 2055 // Don't diagnose in unevaluated contexts. 2056 if (ExprEvalContexts.back().Context == Sema::Unevaluated) 2057 return; 2058 2059 // Don't diagnose for value-dependent expressions. 2060 if (E->isValueDependent()) 2061 return; 2062 2063 const Type *Source = Context.getCanonicalType(E->getType()).getTypePtr(); 2064 const Type *Target = Context.getCanonicalType(T).getTypePtr(); 2065 2066 // Never diagnose implicit casts to bool. 2067 if (Target->isSpecificBuiltinType(BuiltinType::Bool)) 2068 return; 2069 2070 // Strip vector types. 2071 if (isa<VectorType>(Source)) { 2072 if (!isa<VectorType>(Target)) 2073 return DiagnoseImpCast(*this, E, T, diag::warn_impcast_vector_scalar); 2074 2075 Source = cast<VectorType>(Source)->getElementType().getTypePtr(); 2076 Target = cast<VectorType>(Target)->getElementType().getTypePtr(); 2077 } 2078 2079 // Strip complex types. 2080 if (isa<ComplexType>(Source)) { 2081 if (!isa<ComplexType>(Target)) 2082 return DiagnoseImpCast(*this, E, T, diag::warn_impcast_complex_scalar); 2083 2084 Source = cast<ComplexType>(Source)->getElementType().getTypePtr(); 2085 Target = cast<ComplexType>(Target)->getElementType().getTypePtr(); 2086 } 2087 2088 const BuiltinType *SourceBT = dyn_cast<BuiltinType>(Source); 2089 const BuiltinType *TargetBT = dyn_cast<BuiltinType>(Target); 2090 2091 // If the source is floating point... 2092 if (SourceBT && SourceBT->isFloatingPoint()) { 2093 // ...and the target is floating point... 2094 if (TargetBT && TargetBT->isFloatingPoint()) { 2095 // ...then warn if we're dropping FP rank. 2096 2097 // Builtin FP kinds are ordered by increasing FP rank. 2098 if (SourceBT->getKind() > TargetBT->getKind()) { 2099 // Don't warn about float constants that are precisely 2100 // representable in the target type. 2101 Expr::EvalResult result; 2102 if (E->Evaluate(result, Context)) { 2103 // Value might be a float, a float vector, or a float complex. 2104 if (IsSameFloatAfterCast(result.Val, 2105 Context.getFloatTypeSemantics(QualType(TargetBT, 0)), 2106 Context.getFloatTypeSemantics(QualType(SourceBT, 0)))) 2107 return; 2108 } 2109 2110 DiagnoseImpCast(*this, E, T, diag::warn_impcast_float_precision); 2111 } 2112 return; 2113 } 2114 2115 // If the target is integral, always warn. 2116 if ((TargetBT && TargetBT->isInteger())) 2117 // TODO: don't warn for integer values? 2118 return DiagnoseImpCast(*this, E, T, diag::warn_impcast_float_integer); 2119 2120 return; 2121 } 2122 2123 if (!Source->isIntegerType() || !Target->isIntegerType()) 2124 return; 2125 2126 IntRange SourceRange = GetExprRange(Context, E, Context.getIntWidth(E->getType())); 2127 IntRange TargetRange = IntRange::forCanonicalType(Context, Target); 2128 2129 // FIXME: also signed<->unsigned? 2130 2131 if (SourceRange.Width > TargetRange.Width) { 2132 // People want to build with -Wshorten-64-to-32 and not -Wconversion 2133 // and by god we'll let them. 2134 if (SourceRange.Width == 64 && TargetRange.Width == 32) 2135 return DiagnoseImpCast(*this, E, T, diag::warn_impcast_integer_64_32); 2136 return DiagnoseImpCast(*this, E, T, diag::warn_impcast_integer_precision); 2137 } 2138 2139 return; 2140} 2141 2142// MarkLive - Mark all the blocks reachable from e as live. Returns the total 2143// number of blocks just marked live. 2144static unsigned MarkLive(CFGBlock *e, llvm::BitVector &live) { 2145 unsigned count = 0; 2146 std::queue<CFGBlock*> workq; 2147 // Prep work queue 2148 live.set(e->getBlockID()); 2149 ++count; 2150 workq.push(e); 2151 // Solve 2152 while (!workq.empty()) { 2153 CFGBlock *item = workq.front(); 2154 workq.pop(); 2155 for (CFGBlock::succ_iterator I=item->succ_begin(), 2156 E=item->succ_end(); 2157 I != E; 2158 ++I) { 2159 if ((*I) && !live[(*I)->getBlockID()]) { 2160 live.set((*I)->getBlockID()); 2161 ++count; 2162 workq.push(*I); 2163 } 2164 } 2165 } 2166 return count; 2167} 2168 2169static SourceLocation GetUnreachableLoc(CFGBlock &b, SourceRange &R1, 2170 SourceRange &R2) { 2171 Stmt *S; 2172 unsigned sn = 0; 2173 R1 = R2 = SourceRange(); 2174 2175 top: 2176 if (sn < b.size()) 2177 S = b[sn].getStmt(); 2178 else if (b.getTerminator()) 2179 S = b.getTerminator(); 2180 else 2181 return SourceLocation(); 2182 2183 switch (S->getStmtClass()) { 2184 case Expr::BinaryOperatorClass: { 2185 BinaryOperator *BO = cast<BinaryOperator>(S); 2186 if (BO->getOpcode() == BinaryOperator::Comma) { 2187 if (sn+1 < b.size()) 2188 return b[sn+1].getStmt()->getLocStart(); 2189 CFGBlock *n = &b; 2190 while (1) { 2191 if (n->getTerminator()) 2192 return n->getTerminator()->getLocStart(); 2193 if (n->succ_size() != 1) 2194 return SourceLocation(); 2195 n = n[0].succ_begin()[0]; 2196 if (n->pred_size() != 1) 2197 return SourceLocation(); 2198 if (!n->empty()) 2199 return n[0][0].getStmt()->getLocStart(); 2200 } 2201 } 2202 R1 = BO->getLHS()->getSourceRange(); 2203 R2 = BO->getRHS()->getSourceRange(); 2204 return BO->getOperatorLoc(); 2205 } 2206 case Expr::UnaryOperatorClass: { 2207 const UnaryOperator *UO = cast<UnaryOperator>(S); 2208 R1 = UO->getSubExpr()->getSourceRange(); 2209 return UO->getOperatorLoc(); 2210 } 2211 case Expr::CompoundAssignOperatorClass: { 2212 const CompoundAssignOperator *CAO = cast<CompoundAssignOperator>(S); 2213 R1 = CAO->getLHS()->getSourceRange(); 2214 R2 = CAO->getRHS()->getSourceRange(); 2215 return CAO->getOperatorLoc(); 2216 } 2217 case Expr::ConditionalOperatorClass: { 2218 const ConditionalOperator *CO = cast<ConditionalOperator>(S); 2219 return CO->getQuestionLoc(); 2220 } 2221 case Expr::MemberExprClass: { 2222 const MemberExpr *ME = cast<MemberExpr>(S); 2223 R1 = ME->getSourceRange(); 2224 return ME->getMemberLoc(); 2225 } 2226 case Expr::ArraySubscriptExprClass: { 2227 const ArraySubscriptExpr *ASE = cast<ArraySubscriptExpr>(S); 2228 R1 = ASE->getLHS()->getSourceRange(); 2229 R2 = ASE->getRHS()->getSourceRange(); 2230 return ASE->getRBracketLoc(); 2231 } 2232 case Expr::CStyleCastExprClass: { 2233 const CStyleCastExpr *CSC = cast<CStyleCastExpr>(S); 2234 R1 = CSC->getSubExpr()->getSourceRange(); 2235 return CSC->getLParenLoc(); 2236 } 2237 case Expr::CXXFunctionalCastExprClass: { 2238 const CXXFunctionalCastExpr *CE = cast <CXXFunctionalCastExpr>(S); 2239 R1 = CE->getSubExpr()->getSourceRange(); 2240 return CE->getTypeBeginLoc(); 2241 } 2242 case Expr::ImplicitCastExprClass: 2243 ++sn; 2244 goto top; 2245 case Stmt::CXXTryStmtClass: { 2246 return cast<CXXTryStmt>(S)->getHandler(0)->getCatchLoc(); 2247 } 2248 default: ; 2249 } 2250 R1 = S->getSourceRange(); 2251 return S->getLocStart(); 2252} 2253 2254static SourceLocation MarkLiveTop(CFGBlock *e, llvm::BitVector &live, 2255 SourceManager &SM) { 2256 std::queue<CFGBlock*> workq; 2257 // Prep work queue 2258 workq.push(e); 2259 SourceRange R1, R2; 2260 SourceLocation top = GetUnreachableLoc(*e, R1, R2); 2261 bool FromMainFile = false; 2262 bool FromSystemHeader = false; 2263 bool TopValid = false; 2264 if (top.isValid()) { 2265 FromMainFile = SM.isFromMainFile(top); 2266 FromSystemHeader = SM.isInSystemHeader(top); 2267 TopValid = true; 2268 } 2269 // Solve 2270 while (!workq.empty()) { 2271 CFGBlock *item = workq.front(); 2272 workq.pop(); 2273 SourceLocation c = GetUnreachableLoc(*item, R1, R2); 2274 if (c.isValid() 2275 && (!TopValid 2276 || (SM.isFromMainFile(c) && !FromMainFile) 2277 || (FromSystemHeader && !SM.isInSystemHeader(c)) 2278 || SM.isBeforeInTranslationUnit(c, top))) { 2279 top = c; 2280 FromMainFile = SM.isFromMainFile(top); 2281 FromSystemHeader = SM.isInSystemHeader(top); 2282 } 2283 live.set(item->getBlockID()); 2284 for (CFGBlock::succ_iterator I=item->succ_begin(), 2285 E=item->succ_end(); 2286 I != E; 2287 ++I) { 2288 if ((*I) && !live[(*I)->getBlockID()]) { 2289 live.set((*I)->getBlockID()); 2290 workq.push(*I); 2291 } 2292 } 2293 } 2294 return top; 2295} 2296 2297static int LineCmp(const void *p1, const void *p2) { 2298 SourceLocation *Line1 = (SourceLocation *)p1; 2299 SourceLocation *Line2 = (SourceLocation *)p2; 2300 return !(*Line1 < *Line2); 2301} 2302 2303namespace { 2304 struct ErrLoc { 2305 SourceLocation Loc; 2306 SourceRange R1; 2307 SourceRange R2; 2308 ErrLoc(SourceLocation l, SourceRange r1, SourceRange r2) 2309 : Loc(l), R1(r1), R2(r2) { } 2310 }; 2311} 2312 2313/// CheckUnreachable - Check for unreachable code. 2314void Sema::CheckUnreachable(AnalysisContext &AC) { 2315 unsigned count; 2316 // We avoid checking when there are errors, as the CFG won't faithfully match 2317 // the user's code. 2318 if (getDiagnostics().hasErrorOccurred()) 2319 return; 2320 if (Diags.getDiagnosticLevel(diag::warn_unreachable) == Diagnostic::Ignored) 2321 return; 2322 2323 CFG *cfg = AC.getCFG(); 2324 if (cfg == 0) 2325 return; 2326 2327 llvm::BitVector live(cfg->getNumBlockIDs()); 2328 // Mark all live things first. 2329 count = MarkLive(&cfg->getEntry(), live); 2330 2331 if (count == cfg->getNumBlockIDs()) 2332 // If there are no dead blocks, we're done. 2333 return; 2334 2335 SourceRange R1, R2; 2336 2337 llvm::SmallVector<ErrLoc, 24> lines; 2338 bool AddEHEdges = AC.getAddEHEdges(); 2339 // First, give warnings for blocks with no predecessors, as they 2340 // can't be part of a loop. 2341 for (CFG::iterator I = cfg->begin(), E = cfg->end(); I != E; ++I) { 2342 CFGBlock &b = **I; 2343 if (!live[b.getBlockID()]) { 2344 if (b.pred_begin() == b.pred_end()) { 2345 if (!AddEHEdges && b.getTerminator() 2346 && isa<CXXTryStmt>(b.getTerminator())) { 2347 // When not adding EH edges from calls, catch clauses 2348 // can otherwise seem dead. Avoid noting them as dead. 2349 count += MarkLive(&b, live); 2350 continue; 2351 } 2352 SourceLocation c = GetUnreachableLoc(b, R1, R2); 2353 if (!c.isValid()) { 2354 // Blocks without a location can't produce a warning, so don't mark 2355 // reachable blocks from here as live. 2356 live.set(b.getBlockID()); 2357 ++count; 2358 continue; 2359 } 2360 lines.push_back(ErrLoc(c, R1, R2)); 2361 // Avoid excessive errors by marking everything reachable from here 2362 count += MarkLive(&b, live); 2363 } 2364 } 2365 } 2366 2367 if (count < cfg->getNumBlockIDs()) { 2368 // And then give warnings for the tops of loops. 2369 for (CFG::iterator I = cfg->begin(), E = cfg->end(); I != E; ++I) { 2370 CFGBlock &b = **I; 2371 if (!live[b.getBlockID()]) 2372 // Avoid excessive errors by marking everything reachable from here 2373 lines.push_back(ErrLoc(MarkLiveTop(&b, live, 2374 Context.getSourceManager()), 2375 SourceRange(), SourceRange())); 2376 } 2377 } 2378 2379 llvm::array_pod_sort(lines.begin(), lines.end(), LineCmp); 2380 for (llvm::SmallVector<ErrLoc, 24>::iterator I = lines.begin(), 2381 E = lines.end(); 2382 I != E; 2383 ++I) 2384 if (I->Loc.isValid()) 2385 Diag(I->Loc, diag::warn_unreachable) << I->R1 << I->R2; 2386} 2387 2388/// CheckFallThrough - Check that we don't fall off the end of a 2389/// Statement that should return a value. 2390/// 2391/// \returns AlwaysFallThrough iff we always fall off the end of the statement, 2392/// MaybeFallThrough iff we might or might not fall off the end, 2393/// NeverFallThroughOrReturn iff we never fall off the end of the statement or 2394/// return. We assume NeverFallThrough iff we never fall off the end of the 2395/// statement but we may return. We assume that functions not marked noreturn 2396/// will return. 2397Sema::ControlFlowKind Sema::CheckFallThrough(AnalysisContext &AC) { 2398 CFG *cfg = AC.getCFG(); 2399 if (cfg == 0) 2400 // FIXME: This should be NeverFallThrough 2401 return NeverFallThroughOrReturn; 2402 2403 // The CFG leaves in dead things, and we don't want the dead code paths to 2404 // confuse us, so we mark all live things first. 2405 std::queue<CFGBlock*> workq; 2406 llvm::BitVector live(cfg->getNumBlockIDs()); 2407 unsigned count = MarkLive(&cfg->getEntry(), live); 2408 2409 bool AddEHEdges = AC.getAddEHEdges(); 2410 if (!AddEHEdges && count != cfg->getNumBlockIDs()) 2411 // When there are things remaining dead, and we didn't add EH edges 2412 // from CallExprs to the catch clauses, we have to go back and 2413 // mark them as live. 2414 for (CFG::iterator I = cfg->begin(), E = cfg->end(); I != E; ++I) { 2415 CFGBlock &b = **I; 2416 if (!live[b.getBlockID()]) { 2417 if (b.pred_begin() == b.pred_end()) { 2418 if (b.getTerminator() && isa<CXXTryStmt>(b.getTerminator())) 2419 // When not adding EH edges from calls, catch clauses 2420 // can otherwise seem dead. Avoid noting them as dead. 2421 count += MarkLive(&b, live); 2422 continue; 2423 } 2424 } 2425 } 2426 2427 // Now we know what is live, we check the live precessors of the exit block 2428 // and look for fall through paths, being careful to ignore normal returns, 2429 // and exceptional paths. 2430 bool HasLiveReturn = false; 2431 bool HasFakeEdge = false; 2432 bool HasPlainEdge = false; 2433 bool HasAbnormalEdge = false; 2434 for (CFGBlock::pred_iterator I=cfg->getExit().pred_begin(), 2435 E = cfg->getExit().pred_end(); 2436 I != E; 2437 ++I) { 2438 CFGBlock& B = **I; 2439 if (!live[B.getBlockID()]) 2440 continue; 2441 if (B.size() == 0) { 2442 if (B.getTerminator() && isa<CXXTryStmt>(B.getTerminator())) { 2443 HasAbnormalEdge = true; 2444 continue; 2445 } 2446 2447 // A labeled empty statement, or the entry block... 2448 HasPlainEdge = true; 2449 continue; 2450 } 2451 Stmt *S = B[B.size()-1]; 2452 if (isa<ReturnStmt>(S)) { 2453 HasLiveReturn = true; 2454 continue; 2455 } 2456 if (isa<ObjCAtThrowStmt>(S)) { 2457 HasFakeEdge = true; 2458 continue; 2459 } 2460 if (isa<CXXThrowExpr>(S)) { 2461 HasFakeEdge = true; 2462 continue; 2463 } 2464 if (const AsmStmt *AS = dyn_cast<AsmStmt>(S)) { 2465 if (AS->isMSAsm()) { 2466 HasFakeEdge = true; 2467 HasLiveReturn = true; 2468 continue; 2469 } 2470 } 2471 if (isa<CXXTryStmt>(S)) { 2472 HasAbnormalEdge = true; 2473 continue; 2474 } 2475 2476 bool NoReturnEdge = false; 2477 if (CallExpr *C = dyn_cast<CallExpr>(S)) { 2478 if (B.succ_begin()[0] != &cfg->getExit()) { 2479 HasAbnormalEdge = true; 2480 continue; 2481 } 2482 Expr *CEE = C->getCallee()->IgnoreParenCasts(); 2483 if (CEE->getType().getNoReturnAttr()) { 2484 NoReturnEdge = true; 2485 HasFakeEdge = true; 2486 } else if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(CEE)) { 2487 ValueDecl *VD = DRE->getDecl(); 2488 if (VD->hasAttr<NoReturnAttr>()) { 2489 NoReturnEdge = true; 2490 HasFakeEdge = true; 2491 } 2492 } 2493 } 2494 // FIXME: Add noreturn message sends. 2495 if (NoReturnEdge == false) 2496 HasPlainEdge = true; 2497 } 2498 if (!HasPlainEdge) { 2499 if (HasLiveReturn) 2500 return NeverFallThrough; 2501 return NeverFallThroughOrReturn; 2502 } 2503 if (HasAbnormalEdge || HasFakeEdge || HasLiveReturn) 2504 return MaybeFallThrough; 2505 // This says AlwaysFallThrough for calls to functions that are not marked 2506 // noreturn, that don't return. If people would like this warning to be more 2507 // accurate, such functions should be marked as noreturn. 2508 return AlwaysFallThrough; 2509} 2510 2511/// CheckFallThroughForFunctionDef - Check that we don't fall off the end of a 2512/// function that should return a value. Check that we don't fall off the end 2513/// of a noreturn function. We assume that functions and blocks not marked 2514/// noreturn will return. 2515void Sema::CheckFallThroughForFunctionDef(Decl *D, Stmt *Body, 2516 AnalysisContext &AC) { 2517 // FIXME: Would be nice if we had a better way to control cascading errors, 2518 // but for now, avoid them. The problem is that when Parse sees: 2519 // int foo() { return a; } 2520 // The return is eaten and the Sema code sees just: 2521 // int foo() { } 2522 // which this code would then warn about. 2523 if (getDiagnostics().hasErrorOccurred()) 2524 return; 2525 2526 bool ReturnsVoid = false; 2527 bool HasNoReturn = false; 2528 if (FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) { 2529 // For function templates, class templates and member function templates 2530 // we'll do the analysis at instantiation time. 2531 if (FD->isDependentContext()) 2532 return; 2533 2534 if (FD->getResultType()->isVoidType()) 2535 ReturnsVoid = true; 2536 if (FD->hasAttr<NoReturnAttr>() || 2537 FD->getType()->getAs<FunctionType>()->getNoReturnAttr()) 2538 HasNoReturn = true; 2539 } else if (ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(D)) { 2540 if (MD->getResultType()->isVoidType()) 2541 ReturnsVoid = true; 2542 if (MD->hasAttr<NoReturnAttr>()) 2543 HasNoReturn = true; 2544 } 2545 2546 // Short circuit for compilation speed. 2547 if ((Diags.getDiagnosticLevel(diag::warn_maybe_falloff_nonvoid_function) 2548 == Diagnostic::Ignored || ReturnsVoid) 2549 && (Diags.getDiagnosticLevel(diag::warn_noreturn_function_has_return_expr) 2550 == Diagnostic::Ignored || !HasNoReturn) 2551 && (Diags.getDiagnosticLevel(diag::warn_suggest_noreturn_block) 2552 == Diagnostic::Ignored || !ReturnsVoid)) 2553 return; 2554 // FIXME: Function try block 2555 if (CompoundStmt *Compound = dyn_cast<CompoundStmt>(Body)) { 2556 switch (CheckFallThrough(AC)) { 2557 case MaybeFallThrough: 2558 if (HasNoReturn) 2559 Diag(Compound->getRBracLoc(), diag::warn_falloff_noreturn_function); 2560 else if (!ReturnsVoid) 2561 Diag(Compound->getRBracLoc(),diag::warn_maybe_falloff_nonvoid_function); 2562 break; 2563 case AlwaysFallThrough: 2564 if (HasNoReturn) 2565 Diag(Compound->getRBracLoc(), diag::warn_falloff_noreturn_function); 2566 else if (!ReturnsVoid) 2567 Diag(Compound->getRBracLoc(), diag::warn_falloff_nonvoid_function); 2568 break; 2569 case NeverFallThroughOrReturn: 2570 if (ReturnsVoid && !HasNoReturn) 2571 Diag(Compound->getLBracLoc(), diag::warn_suggest_noreturn_function); 2572 break; 2573 case NeverFallThrough: 2574 break; 2575 } 2576 } 2577} 2578 2579/// CheckFallThroughForBlock - Check that we don't fall off the end of a block 2580/// that should return a value. Check that we don't fall off the end of a 2581/// noreturn block. We assume that functions and blocks not marked noreturn 2582/// will return. 2583void Sema::CheckFallThroughForBlock(QualType BlockTy, Stmt *Body, 2584 AnalysisContext &AC) { 2585 // FIXME: Would be nice if we had a better way to control cascading errors, 2586 // but for now, avoid them. The problem is that when Parse sees: 2587 // int foo() { return a; } 2588 // The return is eaten and the Sema code sees just: 2589 // int foo() { } 2590 // which this code would then warn about. 2591 if (getDiagnostics().hasErrorOccurred()) 2592 return; 2593 bool ReturnsVoid = false; 2594 bool HasNoReturn = false; 2595 if (const FunctionType *FT =BlockTy->getPointeeType()->getAs<FunctionType>()){ 2596 if (FT->getResultType()->isVoidType()) 2597 ReturnsVoid = true; 2598 if (FT->getNoReturnAttr()) 2599 HasNoReturn = true; 2600 } 2601 2602 // Short circuit for compilation speed. 2603 if (ReturnsVoid 2604 && !HasNoReturn 2605 && (Diags.getDiagnosticLevel(diag::warn_suggest_noreturn_block) 2606 == Diagnostic::Ignored || !ReturnsVoid)) 2607 return; 2608 // FIXME: Funtion try block 2609 if (CompoundStmt *Compound = dyn_cast<CompoundStmt>(Body)) { 2610 switch (CheckFallThrough(AC)) { 2611 case MaybeFallThrough: 2612 if (HasNoReturn) 2613 Diag(Compound->getRBracLoc(), diag::err_noreturn_block_has_return_expr); 2614 else if (!ReturnsVoid) 2615 Diag(Compound->getRBracLoc(), diag::err_maybe_falloff_nonvoid_block); 2616 break; 2617 case AlwaysFallThrough: 2618 if (HasNoReturn) 2619 Diag(Compound->getRBracLoc(), diag::err_noreturn_block_has_return_expr); 2620 else if (!ReturnsVoid) 2621 Diag(Compound->getRBracLoc(), diag::err_falloff_nonvoid_block); 2622 break; 2623 case NeverFallThroughOrReturn: 2624 if (ReturnsVoid) 2625 Diag(Compound->getLBracLoc(), diag::warn_suggest_noreturn_block); 2626 break; 2627 case NeverFallThrough: 2628 break; 2629 } 2630 } 2631} 2632 2633/// CheckParmsForFunctionDef - Check that the parameters of the given 2634/// function are appropriate for the definition of a function. This 2635/// takes care of any checks that cannot be performed on the 2636/// declaration itself, e.g., that the types of each of the function 2637/// parameters are complete. 2638bool Sema::CheckParmsForFunctionDef(FunctionDecl *FD) { 2639 bool HasInvalidParm = false; 2640 for (unsigned p = 0, NumParams = FD->getNumParams(); p < NumParams; ++p) { 2641 ParmVarDecl *Param = FD->getParamDecl(p); 2642 2643 // C99 6.7.5.3p4: the parameters in a parameter type list in a 2644 // function declarator that is part of a function definition of 2645 // that function shall not have incomplete type. 2646 // 2647 // This is also C++ [dcl.fct]p6. 2648 if (!Param->isInvalidDecl() && 2649 RequireCompleteType(Param->getLocation(), Param->getType(), 2650 diag::err_typecheck_decl_incomplete_type)) { 2651 Param->setInvalidDecl(); 2652 HasInvalidParm = true; 2653 } 2654 2655 // C99 6.9.1p5: If the declarator includes a parameter type list, the 2656 // declaration of each parameter shall include an identifier. 2657 if (Param->getIdentifier() == 0 && 2658 !Param->isImplicit() && 2659 !getLangOptions().CPlusPlus) 2660 Diag(Param->getLocation(), diag::err_parameter_name_omitted); 2661 2662 // C99 6.7.5.3p12: 2663 // If the function declarator is not part of a definition of that 2664 // function, parameters may have incomplete type and may use the [*] 2665 // notation in their sequences of declarator specifiers to specify 2666 // variable length array types. 2667 QualType PType = Param->getOriginalType(); 2668 if (const ArrayType *AT = Context.getAsArrayType(PType)) { 2669 if (AT->getSizeModifier() == ArrayType::Star) { 2670 // FIXME: This diagnosic should point the the '[*]' if source-location 2671 // information is added for it. 2672 Diag(Param->getLocation(), diag::err_array_star_in_function_definition); 2673 } 2674 } 2675 2676 if (getLangOptions().CPlusPlus) 2677 if (const RecordType *RT = Param->getType()->getAs<RecordType>()) 2678 FinalizeVarWithDestructor(Param, RT); 2679 } 2680 2681 return HasInvalidParm; 2682} 2683