SemaChecking.cpp revision 4e4b30ec62d78b24e6556fea2624855c193d0e3e
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_fpclassify: 145 if (SemaBuiltinFPClassification(TheCall, 6)) 146 return ExprError(); 147 break; 148 case Builtin::BI__builtin_isfinite: 149 case Builtin::BI__builtin_isinf: 150 case Builtin::BI__builtin_isinf_sign: 151 case Builtin::BI__builtin_isnan: 152 case Builtin::BI__builtin_isnormal: 153 if (SemaBuiltinFPClassification(TheCall)) 154 return ExprError(); 155 break; 156 case Builtin::BI__builtin_return_address: 157 case Builtin::BI__builtin_frame_address: 158 if (SemaBuiltinStackAddress(TheCall)) 159 return ExprError(); 160 break; 161 case Builtin::BI__builtin_eh_return_data_regno: 162 if (SemaBuiltinEHReturnDataRegNo(TheCall)) 163 return ExprError(); 164 break; 165 case Builtin::BI__builtin_shufflevector: 166 return SemaBuiltinShuffleVector(TheCall); 167 // TheCall will be freed by the smart pointer here, but that's fine, since 168 // SemaBuiltinShuffleVector guts it, but then doesn't release it. 169 case Builtin::BI__builtin_prefetch: 170 if (SemaBuiltinPrefetch(TheCall)) 171 return ExprError(); 172 break; 173 case Builtin::BI__builtin_object_size: 174 if (SemaBuiltinObjectSize(TheCall)) 175 return ExprError(); 176 break; 177 case Builtin::BI__builtin_longjmp: 178 if (SemaBuiltinLongjmp(TheCall)) 179 return ExprError(); 180 break; 181 case Builtin::BI__sync_fetch_and_add: 182 case Builtin::BI__sync_fetch_and_sub: 183 case Builtin::BI__sync_fetch_and_or: 184 case Builtin::BI__sync_fetch_and_and: 185 case Builtin::BI__sync_fetch_and_xor: 186 case Builtin::BI__sync_fetch_and_nand: 187 case Builtin::BI__sync_add_and_fetch: 188 case Builtin::BI__sync_sub_and_fetch: 189 case Builtin::BI__sync_and_and_fetch: 190 case Builtin::BI__sync_or_and_fetch: 191 case Builtin::BI__sync_xor_and_fetch: 192 case Builtin::BI__sync_nand_and_fetch: 193 case Builtin::BI__sync_val_compare_and_swap: 194 case Builtin::BI__sync_bool_compare_and_swap: 195 case Builtin::BI__sync_lock_test_and_set: 196 case Builtin::BI__sync_lock_release: 197 if (SemaBuiltinAtomicOverloaded(TheCall)) 198 return ExprError(); 199 break; 200 } 201 202 return move(TheCallResult); 203} 204 205/// CheckFunctionCall - Check a direct function call for various correctness 206/// and safety properties not strictly enforced by the C type system. 207bool Sema::CheckFunctionCall(FunctionDecl *FDecl, CallExpr *TheCall) { 208 // Get the IdentifierInfo* for the called function. 209 IdentifierInfo *FnInfo = FDecl->getIdentifier(); 210 211 // None of the checks below are needed for functions that don't have 212 // simple names (e.g., C++ conversion functions). 213 if (!FnInfo) 214 return false; 215 216 // FIXME: This mechanism should be abstracted to be less fragile and 217 // more efficient. For example, just map function ids to custom 218 // handlers. 219 220 // Printf checking. 221 if (const FormatAttr *Format = FDecl->getAttr<FormatAttr>()) { 222 if (CheckablePrintfAttr(Format, TheCall)) { 223 bool HasVAListArg = Format->getFirstArg() == 0; 224 if (!HasVAListArg) { 225 if (const FunctionProtoType *Proto 226 = FDecl->getType()->getAs<FunctionProtoType>()) 227 HasVAListArg = !Proto->isVariadic(); 228 } 229 CheckPrintfArguments(TheCall, HasVAListArg, Format->getFormatIdx() - 1, 230 HasVAListArg ? 0 : Format->getFirstArg() - 1); 231 } 232 } 233 234 for (const NonNullAttr *NonNull = FDecl->getAttr<NonNullAttr>(); NonNull; 235 NonNull = NonNull->getNext<NonNullAttr>()) 236 CheckNonNullArguments(NonNull, TheCall); 237 238 return false; 239} 240 241bool Sema::CheckBlockCall(NamedDecl *NDecl, CallExpr *TheCall) { 242 // Printf checking. 243 const FormatAttr *Format = NDecl->getAttr<FormatAttr>(); 244 if (!Format) 245 return false; 246 247 const VarDecl *V = dyn_cast<VarDecl>(NDecl); 248 if (!V) 249 return false; 250 251 QualType Ty = V->getType(); 252 if (!Ty->isBlockPointerType()) 253 return false; 254 255 if (!CheckablePrintfAttr(Format, TheCall)) 256 return false; 257 258 bool HasVAListArg = Format->getFirstArg() == 0; 259 if (!HasVAListArg) { 260 const FunctionType *FT = 261 Ty->getAs<BlockPointerType>()->getPointeeType()->getAs<FunctionType>(); 262 if (const FunctionProtoType *Proto = dyn_cast<FunctionProtoType>(FT)) 263 HasVAListArg = !Proto->isVariadic(); 264 } 265 CheckPrintfArguments(TheCall, HasVAListArg, Format->getFormatIdx() - 1, 266 HasVAListArg ? 0 : Format->getFirstArg() - 1); 267 268 return false; 269} 270 271/// SemaBuiltinAtomicOverloaded - We have a call to a function like 272/// __sync_fetch_and_add, which is an overloaded function based on the pointer 273/// type of its first argument. The main ActOnCallExpr routines have already 274/// promoted the types of arguments because all of these calls are prototyped as 275/// void(...). 276/// 277/// This function goes through and does final semantic checking for these 278/// builtins, 279bool Sema::SemaBuiltinAtomicOverloaded(CallExpr *TheCall) { 280 DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts()); 281 FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl()); 282 283 // Ensure that we have at least one argument to do type inference from. 284 if (TheCall->getNumArgs() < 1) 285 return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args) 286 << 0 << TheCall->getCallee()->getSourceRange(); 287 288 // Inspect the first argument of the atomic builtin. This should always be 289 // a pointer type, whose element is an integral scalar or pointer type. 290 // Because it is a pointer type, we don't have to worry about any implicit 291 // casts here. 292 Expr *FirstArg = TheCall->getArg(0); 293 if (!FirstArg->getType()->isPointerType()) 294 return Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer) 295 << FirstArg->getType() << FirstArg->getSourceRange(); 296 297 QualType ValType = FirstArg->getType()->getAs<PointerType>()->getPointeeType(); 298 if (!ValType->isIntegerType() && !ValType->isPointerType() && 299 !ValType->isBlockPointerType()) 300 return Diag(DRE->getLocStart(), 301 diag::err_atomic_builtin_must_be_pointer_intptr) 302 << FirstArg->getType() << FirstArg->getSourceRange(); 303 304 // We need to figure out which concrete builtin this maps onto. For example, 305 // __sync_fetch_and_add with a 2 byte object turns into 306 // __sync_fetch_and_add_2. 307#define BUILTIN_ROW(x) \ 308 { Builtin::BI##x##_1, Builtin::BI##x##_2, Builtin::BI##x##_4, \ 309 Builtin::BI##x##_8, Builtin::BI##x##_16 } 310 311 static const unsigned BuiltinIndices[][5] = { 312 BUILTIN_ROW(__sync_fetch_and_add), 313 BUILTIN_ROW(__sync_fetch_and_sub), 314 BUILTIN_ROW(__sync_fetch_and_or), 315 BUILTIN_ROW(__sync_fetch_and_and), 316 BUILTIN_ROW(__sync_fetch_and_xor), 317 BUILTIN_ROW(__sync_fetch_and_nand), 318 319 BUILTIN_ROW(__sync_add_and_fetch), 320 BUILTIN_ROW(__sync_sub_and_fetch), 321 BUILTIN_ROW(__sync_and_and_fetch), 322 BUILTIN_ROW(__sync_or_and_fetch), 323 BUILTIN_ROW(__sync_xor_and_fetch), 324 BUILTIN_ROW(__sync_nand_and_fetch), 325 326 BUILTIN_ROW(__sync_val_compare_and_swap), 327 BUILTIN_ROW(__sync_bool_compare_and_swap), 328 BUILTIN_ROW(__sync_lock_test_and_set), 329 BUILTIN_ROW(__sync_lock_release) 330 }; 331#undef BUILTIN_ROW 332 333 // Determine the index of the size. 334 unsigned SizeIndex; 335 switch (Context.getTypeSizeInChars(ValType).getQuantity()) { 336 case 1: SizeIndex = 0; break; 337 case 2: SizeIndex = 1; break; 338 case 4: SizeIndex = 2; break; 339 case 8: SizeIndex = 3; break; 340 case 16: SizeIndex = 4; break; 341 default: 342 return Diag(DRE->getLocStart(), diag::err_atomic_builtin_pointer_size) 343 << FirstArg->getType() << FirstArg->getSourceRange(); 344 } 345 346 // Each of these builtins has one pointer argument, followed by some number of 347 // values (0, 1 or 2) followed by a potentially empty varags list of stuff 348 // that we ignore. Find out which row of BuiltinIndices to read from as well 349 // as the number of fixed args. 350 unsigned BuiltinID = FDecl->getBuiltinID(); 351 unsigned BuiltinIndex, NumFixed = 1; 352 switch (BuiltinID) { 353 default: assert(0 && "Unknown overloaded atomic builtin!"); 354 case Builtin::BI__sync_fetch_and_add: BuiltinIndex = 0; break; 355 case Builtin::BI__sync_fetch_and_sub: BuiltinIndex = 1; break; 356 case Builtin::BI__sync_fetch_and_or: BuiltinIndex = 2; break; 357 case Builtin::BI__sync_fetch_and_and: BuiltinIndex = 3; break; 358 case Builtin::BI__sync_fetch_and_xor: BuiltinIndex = 4; break; 359 case Builtin::BI__sync_fetch_and_nand:BuiltinIndex = 5; break; 360 361 case Builtin::BI__sync_add_and_fetch: BuiltinIndex = 6; break; 362 case Builtin::BI__sync_sub_and_fetch: BuiltinIndex = 7; break; 363 case Builtin::BI__sync_and_and_fetch: BuiltinIndex = 8; break; 364 case Builtin::BI__sync_or_and_fetch: BuiltinIndex = 9; break; 365 case Builtin::BI__sync_xor_and_fetch: BuiltinIndex =10; break; 366 case Builtin::BI__sync_nand_and_fetch:BuiltinIndex =11; break; 367 368 case Builtin::BI__sync_val_compare_and_swap: 369 BuiltinIndex = 12; 370 NumFixed = 2; 371 break; 372 case Builtin::BI__sync_bool_compare_and_swap: 373 BuiltinIndex = 13; 374 NumFixed = 2; 375 break; 376 case Builtin::BI__sync_lock_test_and_set: BuiltinIndex = 14; break; 377 case Builtin::BI__sync_lock_release: 378 BuiltinIndex = 15; 379 NumFixed = 0; 380 break; 381 } 382 383 // Now that we know how many fixed arguments we expect, first check that we 384 // have at least that many. 385 if (TheCall->getNumArgs() < 1+NumFixed) 386 return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args) 387 << 0 << TheCall->getCallee()->getSourceRange(); 388 389 390 // Get the decl for the concrete builtin from this, we can tell what the 391 // concrete integer type we should convert to is. 392 unsigned NewBuiltinID = BuiltinIndices[BuiltinIndex][SizeIndex]; 393 const char *NewBuiltinName = Context.BuiltinInfo.GetName(NewBuiltinID); 394 IdentifierInfo *NewBuiltinII = PP.getIdentifierInfo(NewBuiltinName); 395 FunctionDecl *NewBuiltinDecl = 396 cast<FunctionDecl>(LazilyCreateBuiltin(NewBuiltinII, NewBuiltinID, 397 TUScope, false, DRE->getLocStart())); 398 const FunctionProtoType *BuiltinFT = 399 NewBuiltinDecl->getType()->getAs<FunctionProtoType>(); 400 ValType = BuiltinFT->getArgType(0)->getAs<PointerType>()->getPointeeType(); 401 402 // If the first type needs to be converted (e.g. void** -> int*), do it now. 403 if (BuiltinFT->getArgType(0) != FirstArg->getType()) { 404 ImpCastExprToType(FirstArg, BuiltinFT->getArgType(0), CastExpr::CK_BitCast); 405 TheCall->setArg(0, FirstArg); 406 } 407 408 // Next, walk the valid ones promoting to the right type. 409 for (unsigned i = 0; i != NumFixed; ++i) { 410 Expr *Arg = TheCall->getArg(i+1); 411 412 // If the argument is an implicit cast, then there was a promotion due to 413 // "...", just remove it now. 414 if (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Arg)) { 415 Arg = ICE->getSubExpr(); 416 ICE->setSubExpr(0); 417 ICE->Destroy(Context); 418 TheCall->setArg(i+1, Arg); 419 } 420 421 // GCC does an implicit conversion to the pointer or integer ValType. This 422 // can fail in some cases (1i -> int**), check for this error case now. 423 CastExpr::CastKind Kind = CastExpr::CK_Unknown; 424 CXXMethodDecl *ConversionDecl = 0; 425 if (CheckCastTypes(Arg->getSourceRange(), ValType, Arg, Kind, 426 ConversionDecl)) 427 return true; 428 429 // Okay, we have something that *can* be converted to the right type. Check 430 // to see if there is a potentially weird extension going on here. This can 431 // happen when you do an atomic operation on something like an char* and 432 // pass in 42. The 42 gets converted to char. This is even more strange 433 // for things like 45.123 -> char, etc. 434 // FIXME: Do this check. 435 ImpCastExprToType(Arg, ValType, Kind, /*isLvalue=*/false); 436 TheCall->setArg(i+1, Arg); 437 } 438 439 // Switch the DeclRefExpr to refer to the new decl. 440 DRE->setDecl(NewBuiltinDecl); 441 DRE->setType(NewBuiltinDecl->getType()); 442 443 // Set the callee in the CallExpr. 444 // FIXME: This leaks the original parens and implicit casts. 445 Expr *PromotedCall = DRE; 446 UsualUnaryConversions(PromotedCall); 447 TheCall->setCallee(PromotedCall); 448 449 450 // Change the result type of the call to match the result type of the decl. 451 TheCall->setType(NewBuiltinDecl->getResultType()); 452 return false; 453} 454 455 456/// CheckObjCString - Checks that the argument to the builtin 457/// CFString constructor is correct 458/// FIXME: GCC currently emits the following warning: 459/// "warning: input conversion stopped due to an input byte that does not 460/// belong to the input codeset UTF-8" 461/// Note: It might also make sense to do the UTF-16 conversion here (would 462/// simplify the backend). 463bool Sema::CheckObjCString(Expr *Arg) { 464 Arg = Arg->IgnoreParenCasts(); 465 StringLiteral *Literal = dyn_cast<StringLiteral>(Arg); 466 467 if (!Literal || Literal->isWide()) { 468 Diag(Arg->getLocStart(), diag::err_cfstring_literal_not_string_constant) 469 << Arg->getSourceRange(); 470 return true; 471 } 472 473 const char *Data = Literal->getStrData(); 474 unsigned Length = Literal->getByteLength(); 475 476 for (unsigned i = 0; i < Length; ++i) { 477 if (!Data[i]) { 478 Diag(getLocationOfStringLiteralByte(Literal, i), 479 diag::warn_cfstring_literal_contains_nul_character) 480 << Arg->getSourceRange(); 481 break; 482 } 483 } 484 485 return false; 486} 487 488/// SemaBuiltinVAStart - Check the arguments to __builtin_va_start for validity. 489/// Emit an error and return true on failure, return false on success. 490bool Sema::SemaBuiltinVAStart(CallExpr *TheCall) { 491 Expr *Fn = TheCall->getCallee(); 492 if (TheCall->getNumArgs() > 2) { 493 Diag(TheCall->getArg(2)->getLocStart(), 494 diag::err_typecheck_call_too_many_args) 495 << 0 /*function call*/ << Fn->getSourceRange() 496 << SourceRange(TheCall->getArg(2)->getLocStart(), 497 (*(TheCall->arg_end()-1))->getLocEnd()); 498 return true; 499 } 500 501 if (TheCall->getNumArgs() < 2) { 502 return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args) 503 << 0 /*function call*/; 504 } 505 506 // Determine whether the current function is variadic or not. 507 bool isVariadic; 508 if (CurBlock) 509 isVariadic = CurBlock->isVariadic; 510 else if (getCurFunctionDecl()) { 511 if (FunctionProtoType* FTP = 512 dyn_cast<FunctionProtoType>(getCurFunctionDecl()->getType())) 513 isVariadic = FTP->isVariadic(); 514 else 515 isVariadic = false; 516 } else { 517 isVariadic = getCurMethodDecl()->isVariadic(); 518 } 519 520 if (!isVariadic) { 521 Diag(Fn->getLocStart(), diag::err_va_start_used_in_non_variadic_function); 522 return true; 523 } 524 525 // Verify that the second argument to the builtin is the last argument of the 526 // current function or method. 527 bool SecondArgIsLastNamedArgument = false; 528 const Expr *Arg = TheCall->getArg(1)->IgnoreParenCasts(); 529 530 if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Arg)) { 531 if (const ParmVarDecl *PV = dyn_cast<ParmVarDecl>(DR->getDecl())) { 532 // FIXME: This isn't correct for methods (results in bogus warning). 533 // Get the last formal in the current function. 534 const ParmVarDecl *LastArg; 535 if (CurBlock) 536 LastArg = *(CurBlock->TheDecl->param_end()-1); 537 else if (FunctionDecl *FD = getCurFunctionDecl()) 538 LastArg = *(FD->param_end()-1); 539 else 540 LastArg = *(getCurMethodDecl()->param_end()-1); 541 SecondArgIsLastNamedArgument = PV == LastArg; 542 } 543 } 544 545 if (!SecondArgIsLastNamedArgument) 546 Diag(TheCall->getArg(1)->getLocStart(), 547 diag::warn_second_parameter_of_va_start_not_last_named_argument); 548 return false; 549} 550 551/// SemaBuiltinUnorderedCompare - Handle functions like __builtin_isgreater and 552/// friends. This is declared to take (...), so we have to check everything. 553bool Sema::SemaBuiltinUnorderedCompare(CallExpr *TheCall) { 554 if (TheCall->getNumArgs() < 2) 555 return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args) 556 << 0 /*function call*/; 557 if (TheCall->getNumArgs() > 2) 558 return Diag(TheCall->getArg(2)->getLocStart(), 559 diag::err_typecheck_call_too_many_args) 560 << 0 /*function call*/ 561 << SourceRange(TheCall->getArg(2)->getLocStart(), 562 (*(TheCall->arg_end()-1))->getLocEnd()); 563 564 Expr *OrigArg0 = TheCall->getArg(0); 565 Expr *OrigArg1 = TheCall->getArg(1); 566 567 // Do standard promotions between the two arguments, returning their common 568 // type. 569 QualType Res = UsualArithmeticConversions(OrigArg0, OrigArg1, false); 570 571 // Make sure any conversions are pushed back into the call; this is 572 // type safe since unordered compare builtins are declared as "_Bool 573 // foo(...)". 574 TheCall->setArg(0, OrigArg0); 575 TheCall->setArg(1, OrigArg1); 576 577 if (OrigArg0->isTypeDependent() || OrigArg1->isTypeDependent()) 578 return false; 579 580 // If the common type isn't a real floating type, then the arguments were 581 // invalid for this operation. 582 if (!Res->isRealFloatingType()) 583 return Diag(OrigArg0->getLocStart(), 584 diag::err_typecheck_call_invalid_ordered_compare) 585 << OrigArg0->getType() << OrigArg1->getType() 586 << SourceRange(OrigArg0->getLocStart(), OrigArg1->getLocEnd()); 587 588 return false; 589} 590 591/// SemaBuiltinSemaBuiltinFPClassification - Handle functions like 592/// __builtin_isnan and friends. This is declared to take (...), so we have 593/// to check everything. 594bool Sema::SemaBuiltinFPClassification(CallExpr *TheCall, unsigned LastArg) { 595 if (TheCall->getNumArgs() < LastArg) 596 return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args) 597 << 0 /*function call*/; 598 if (TheCall->getNumArgs() > LastArg) 599 return Diag(TheCall->getArg(LastArg)->getLocStart(), 600 diag::err_typecheck_call_too_many_args) 601 << 0 /*function call*/ 602 << SourceRange(TheCall->getArg(LastArg)->getLocStart(), 603 (*(TheCall->arg_end()-1))->getLocEnd()); 604 605 Expr *OrigArg = TheCall->getArg(LastArg-1); 606 607 if (OrigArg->isTypeDependent()) 608 return false; 609 610 // This operation requires a floating-point number 611 if (!OrigArg->getType()->isRealFloatingType()) 612 return Diag(OrigArg->getLocStart(), 613 diag::err_typecheck_call_invalid_unary_fp) 614 << OrigArg->getType() << OrigArg->getSourceRange(); 615 616 return false; 617} 618 619bool Sema::SemaBuiltinStackAddress(CallExpr *TheCall) { 620 // The signature for these builtins is exact; the only thing we need 621 // to check is that the argument is a constant. 622 SourceLocation Loc; 623 if (!TheCall->getArg(0)->isTypeDependent() && 624 !TheCall->getArg(0)->isValueDependent() && 625 !TheCall->getArg(0)->isIntegerConstantExpr(Context, &Loc)) 626 return Diag(Loc, diag::err_stack_const_level) << TheCall->getSourceRange(); 627 628 return false; 629} 630 631/// SemaBuiltinShuffleVector - Handle __builtin_shufflevector. 632// This is declared to take (...), so we have to check everything. 633Action::OwningExprResult Sema::SemaBuiltinShuffleVector(CallExpr *TheCall) { 634 if (TheCall->getNumArgs() < 3) 635 return ExprError(Diag(TheCall->getLocEnd(), 636 diag::err_typecheck_call_too_few_args) 637 << 0 /*function call*/ << TheCall->getSourceRange()); 638 639 unsigned numElements = std::numeric_limits<unsigned>::max(); 640 if (!TheCall->getArg(0)->isTypeDependent() && 641 !TheCall->getArg(1)->isTypeDependent()) { 642 QualType FAType = TheCall->getArg(0)->getType(); 643 QualType SAType = TheCall->getArg(1)->getType(); 644 645 if (!FAType->isVectorType() || !SAType->isVectorType()) { 646 Diag(TheCall->getLocStart(), diag::err_shufflevector_non_vector) 647 << SourceRange(TheCall->getArg(0)->getLocStart(), 648 TheCall->getArg(1)->getLocEnd()); 649 return ExprError(); 650 } 651 652 if (!Context.hasSameUnqualifiedType(FAType, SAType)) { 653 Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector) 654 << SourceRange(TheCall->getArg(0)->getLocStart(), 655 TheCall->getArg(1)->getLocEnd()); 656 return ExprError(); 657 } 658 659 numElements = FAType->getAs<VectorType>()->getNumElements(); 660 if (TheCall->getNumArgs() != numElements+2) { 661 if (TheCall->getNumArgs() < numElements+2) 662 return ExprError(Diag(TheCall->getLocEnd(), 663 diag::err_typecheck_call_too_few_args) 664 << 0 /*function call*/ << TheCall->getSourceRange()); 665 return ExprError(Diag(TheCall->getLocEnd(), 666 diag::err_typecheck_call_too_many_args) 667 << 0 /*function call*/ << TheCall->getSourceRange()); 668 } 669 } 670 671 for (unsigned i = 2; i < TheCall->getNumArgs(); i++) { 672 if (TheCall->getArg(i)->isTypeDependent() || 673 TheCall->getArg(i)->isValueDependent()) 674 continue; 675 676 llvm::APSInt Result(32); 677 if (!TheCall->getArg(i)->isIntegerConstantExpr(Result, Context)) 678 return ExprError(Diag(TheCall->getLocStart(), 679 diag::err_shufflevector_nonconstant_argument) 680 << TheCall->getArg(i)->getSourceRange()); 681 682 if (Result.getActiveBits() > 64 || Result.getZExtValue() >= numElements*2) 683 return ExprError(Diag(TheCall->getLocStart(), 684 diag::err_shufflevector_argument_too_large) 685 << TheCall->getArg(i)->getSourceRange()); 686 } 687 688 llvm::SmallVector<Expr*, 32> exprs; 689 690 for (unsigned i = 0, e = TheCall->getNumArgs(); i != e; i++) { 691 exprs.push_back(TheCall->getArg(i)); 692 TheCall->setArg(i, 0); 693 } 694 695 return Owned(new (Context) ShuffleVectorExpr(Context, exprs.begin(), 696 exprs.size(), exprs[0]->getType(), 697 TheCall->getCallee()->getLocStart(), 698 TheCall->getRParenLoc())); 699} 700 701/// SemaBuiltinPrefetch - Handle __builtin_prefetch. 702// This is declared to take (const void*, ...) and can take two 703// optional constant int args. 704bool Sema::SemaBuiltinPrefetch(CallExpr *TheCall) { 705 unsigned NumArgs = TheCall->getNumArgs(); 706 707 if (NumArgs > 3) 708 return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_many_args) 709 << 0 /*function call*/ << TheCall->getSourceRange(); 710 711 // Argument 0 is checked for us and the remaining arguments must be 712 // constant integers. 713 for (unsigned i = 1; i != NumArgs; ++i) { 714 Expr *Arg = TheCall->getArg(i); 715 if (Arg->isTypeDependent()) 716 continue; 717 718 if (!Arg->getType()->isIntegralType()) 719 return Diag(TheCall->getLocStart(), diag::err_prefetch_invalid_arg_type) 720 << Arg->getSourceRange(); 721 722 ImpCastExprToType(Arg, Context.IntTy, CastExpr::CK_IntegralCast); 723 TheCall->setArg(i, Arg); 724 725 if (Arg->isValueDependent()) 726 continue; 727 728 llvm::APSInt Result; 729 if (!Arg->isIntegerConstantExpr(Result, Context)) 730 return Diag(TheCall->getLocStart(), diag::err_prefetch_invalid_arg_ice) 731 << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); 732 733 // FIXME: gcc issues a warning and rewrites these to 0. These 734 // seems especially odd for the third argument since the default 735 // is 3. 736 if (i == 1) { 737 if (Result.getLimitedValue() > 1) 738 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 739 << "0" << "1" << Arg->getSourceRange(); 740 } else { 741 if (Result.getLimitedValue() > 3) 742 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 743 << "0" << "3" << Arg->getSourceRange(); 744 } 745 } 746 747 return false; 748} 749 750/// SemaBuiltinEHReturnDataRegNo - Handle __builtin_eh_return_data_regno, the 751/// operand must be an integer constant. 752bool Sema::SemaBuiltinEHReturnDataRegNo(CallExpr *TheCall) { 753 llvm::APSInt Result; 754 if (!TheCall->getArg(0)->isIntegerConstantExpr(Result, Context)) 755 return Diag(TheCall->getLocStart(), diag::err_expr_not_ice) 756 << TheCall->getArg(0)->getSourceRange(); 757 758 return false; 759} 760 761 762/// SemaBuiltinObjectSize - Handle __builtin_object_size(void *ptr, 763/// int type). This simply type checks that type is one of the defined 764/// constants (0-3). 765// For compatability check 0-3, llvm only handles 0 and 2. 766bool Sema::SemaBuiltinObjectSize(CallExpr *TheCall) { 767 Expr *Arg = TheCall->getArg(1); 768 if (Arg->isTypeDependent()) 769 return false; 770 771 QualType ArgType = Arg->getType(); 772 const BuiltinType *BT = ArgType->getAs<BuiltinType>(); 773 llvm::APSInt Result(32); 774 if (!BT || BT->getKind() != BuiltinType::Int) 775 return Diag(TheCall->getLocStart(), diag::err_object_size_invalid_argument) 776 << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); 777 778 if (Arg->isValueDependent()) 779 return false; 780 781 if (!Arg->isIntegerConstantExpr(Result, Context)) { 782 return Diag(TheCall->getLocStart(), diag::err_object_size_invalid_argument) 783 << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); 784 } 785 786 if (Result.getSExtValue() < 0 || Result.getSExtValue() > 3) { 787 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 788 << "0" << "3" << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); 789 } 790 791 return false; 792} 793 794/// SemaBuiltinLongjmp - Handle __builtin_longjmp(void *env[5], int val). 795/// This checks that val is a constant 1. 796bool Sema::SemaBuiltinLongjmp(CallExpr *TheCall) { 797 Expr *Arg = TheCall->getArg(1); 798 if (Arg->isTypeDependent() || Arg->isValueDependent()) 799 return false; 800 801 llvm::APSInt Result(32); 802 if (!Arg->isIntegerConstantExpr(Result, Context) || Result != 1) 803 return Diag(TheCall->getLocStart(), diag::err_builtin_longjmp_invalid_val) 804 << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); 805 806 return false; 807} 808 809// Handle i > 1 ? "x" : "y", recursivelly 810bool Sema::SemaCheckStringLiteral(const Expr *E, const CallExpr *TheCall, 811 bool HasVAListArg, 812 unsigned format_idx, unsigned firstDataArg) { 813 if (E->isTypeDependent() || E->isValueDependent()) 814 return false; 815 816 switch (E->getStmtClass()) { 817 case Stmt::ConditionalOperatorClass: { 818 const ConditionalOperator *C = cast<ConditionalOperator>(E); 819 return SemaCheckStringLiteral(C->getTrueExpr(), TheCall, 820 HasVAListArg, format_idx, firstDataArg) 821 && SemaCheckStringLiteral(C->getRHS(), TheCall, 822 HasVAListArg, format_idx, firstDataArg); 823 } 824 825 case Stmt::ImplicitCastExprClass: { 826 const ImplicitCastExpr *Expr = cast<ImplicitCastExpr>(E); 827 return SemaCheckStringLiteral(Expr->getSubExpr(), TheCall, HasVAListArg, 828 format_idx, firstDataArg); 829 } 830 831 case Stmt::ParenExprClass: { 832 const ParenExpr *Expr = cast<ParenExpr>(E); 833 return SemaCheckStringLiteral(Expr->getSubExpr(), TheCall, HasVAListArg, 834 format_idx, firstDataArg); 835 } 836 837 case Stmt::DeclRefExprClass: { 838 const DeclRefExpr *DR = cast<DeclRefExpr>(E); 839 840 // As an exception, do not flag errors for variables binding to 841 // const string literals. 842 if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) { 843 bool isConstant = false; 844 QualType T = DR->getType(); 845 846 if (const ArrayType *AT = Context.getAsArrayType(T)) { 847 isConstant = AT->getElementType().isConstant(Context); 848 } else if (const PointerType *PT = T->getAs<PointerType>()) { 849 isConstant = T.isConstant(Context) && 850 PT->getPointeeType().isConstant(Context); 851 } 852 853 if (isConstant) { 854 if (const Expr *Init = VD->getAnyInitializer()) 855 return SemaCheckStringLiteral(Init, TheCall, 856 HasVAListArg, format_idx, firstDataArg); 857 } 858 859 // For vprintf* functions (i.e., HasVAListArg==true), we add a 860 // special check to see if the format string is a function parameter 861 // of the function calling the printf function. If the function 862 // has an attribute indicating it is a printf-like function, then we 863 // should suppress warnings concerning non-literals being used in a call 864 // to a vprintf function. For example: 865 // 866 // void 867 // logmessage(char const *fmt __attribute__ (format (printf, 1, 2)), ...){ 868 // va_list ap; 869 // va_start(ap, fmt); 870 // vprintf(fmt, ap); // Do NOT emit a warning about "fmt". 871 // ... 872 // 873 // 874 // FIXME: We don't have full attribute support yet, so just check to see 875 // if the argument is a DeclRefExpr that references a parameter. We'll 876 // add proper support for checking the attribute later. 877 if (HasVAListArg) 878 if (isa<ParmVarDecl>(VD)) 879 return true; 880 } 881 882 return false; 883 } 884 885 case Stmt::CallExprClass: { 886 const CallExpr *CE = cast<CallExpr>(E); 887 if (const ImplicitCastExpr *ICE 888 = dyn_cast<ImplicitCastExpr>(CE->getCallee())) { 889 if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(ICE->getSubExpr())) { 890 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(DRE->getDecl())) { 891 if (const FormatArgAttr *FA = FD->getAttr<FormatArgAttr>()) { 892 unsigned ArgIndex = FA->getFormatIdx(); 893 const Expr *Arg = CE->getArg(ArgIndex - 1); 894 895 return SemaCheckStringLiteral(Arg, TheCall, HasVAListArg, 896 format_idx, firstDataArg); 897 } 898 } 899 } 900 } 901 902 return false; 903 } 904 case Stmt::ObjCStringLiteralClass: 905 case Stmt::StringLiteralClass: { 906 const StringLiteral *StrE = NULL; 907 908 if (const ObjCStringLiteral *ObjCFExpr = dyn_cast<ObjCStringLiteral>(E)) 909 StrE = ObjCFExpr->getString(); 910 else 911 StrE = cast<StringLiteral>(E); 912 913 if (StrE) { 914 CheckPrintfString(StrE, E, TheCall, HasVAListArg, format_idx, 915 firstDataArg); 916 return true; 917 } 918 919 return false; 920 } 921 922 default: 923 return false; 924 } 925} 926 927void 928Sema::CheckNonNullArguments(const NonNullAttr *NonNull, 929 const CallExpr *TheCall) { 930 for (NonNullAttr::iterator i = NonNull->begin(), e = NonNull->end(); 931 i != e; ++i) { 932 const Expr *ArgExpr = TheCall->getArg(*i); 933 if (ArgExpr->isNullPointerConstant(Context, 934 Expr::NPC_ValueDependentIsNotNull)) 935 Diag(TheCall->getCallee()->getLocStart(), diag::warn_null_arg) 936 << ArgExpr->getSourceRange(); 937 } 938} 939 940/// CheckPrintfArguments - Check calls to printf (and similar functions) for 941/// correct use of format strings. 942/// 943/// HasVAListArg - A predicate indicating whether the printf-like 944/// function is passed an explicit va_arg argument (e.g., vprintf) 945/// 946/// format_idx - The index into Args for the format string. 947/// 948/// Improper format strings to functions in the printf family can be 949/// the source of bizarre bugs and very serious security holes. A 950/// good source of information is available in the following paper 951/// (which includes additional references): 952/// 953/// FormatGuard: Automatic Protection From printf Format String 954/// Vulnerabilities, Proceedings of the 10th USENIX Security Symposium, 2001. 955/// 956/// Functionality implemented: 957/// 958/// We can statically check the following properties for string 959/// literal format strings for non v.*printf functions (where the 960/// arguments are passed directly): 961// 962/// (1) Are the number of format conversions equal to the number of 963/// data arguments? 964/// 965/// (2) Does each format conversion correctly match the type of the 966/// corresponding data argument? (TODO) 967/// 968/// Moreover, for all printf functions we can: 969/// 970/// (3) Check for a missing format string (when not caught by type checking). 971/// 972/// (4) Check for no-operation flags; e.g. using "#" with format 973/// conversion 'c' (TODO) 974/// 975/// (5) Check the use of '%n', a major source of security holes. 976/// 977/// (6) Check for malformed format conversions that don't specify anything. 978/// 979/// (7) Check for empty format strings. e.g: printf(""); 980/// 981/// (8) Check that the format string is a wide literal. 982/// 983/// All of these checks can be done by parsing the format string. 984/// 985/// For now, we ONLY do (1), (3), (5), (6), (7), and (8). 986void 987Sema::CheckPrintfArguments(const CallExpr *TheCall, bool HasVAListArg, 988 unsigned format_idx, unsigned firstDataArg) { 989 const Expr *Fn = TheCall->getCallee(); 990 991 // The way the format attribute works in GCC, the implicit this argument 992 // of member functions is counted. However, it doesn't appear in our own 993 // lists, so decrement format_idx in that case. 994 if (isa<CXXMemberCallExpr>(TheCall)) { 995 // Catch a format attribute mistakenly referring to the object argument. 996 if (format_idx == 0) 997 return; 998 --format_idx; 999 if(firstDataArg != 0) 1000 --firstDataArg; 1001 } 1002 1003 // CHECK: printf-like function is called with no format string. 1004 if (format_idx >= TheCall->getNumArgs()) { 1005 Diag(TheCall->getRParenLoc(), diag::warn_printf_missing_format_string) 1006 << Fn->getSourceRange(); 1007 return; 1008 } 1009 1010 const Expr *OrigFormatExpr = TheCall->getArg(format_idx)->IgnoreParenCasts(); 1011 1012 // CHECK: format string is not a string literal. 1013 // 1014 // Dynamically generated format strings are difficult to 1015 // automatically vet at compile time. Requiring that format strings 1016 // are string literals: (1) permits the checking of format strings by 1017 // the compiler and thereby (2) can practically remove the source of 1018 // many format string exploits. 1019 1020 // Format string can be either ObjC string (e.g. @"%d") or 1021 // C string (e.g. "%d") 1022 // ObjC string uses the same format specifiers as C string, so we can use 1023 // the same format string checking logic for both ObjC and C strings. 1024 if (SemaCheckStringLiteral(OrigFormatExpr, TheCall, HasVAListArg, format_idx, 1025 firstDataArg)) 1026 return; // Literal format string found, check done! 1027 1028 // If there are no arguments specified, warn with -Wformat-security, otherwise 1029 // warn only with -Wformat-nonliteral. 1030 if (TheCall->getNumArgs() == format_idx+1) 1031 Diag(TheCall->getArg(format_idx)->getLocStart(), 1032 diag::warn_printf_nonliteral_noargs) 1033 << OrigFormatExpr->getSourceRange(); 1034 else 1035 Diag(TheCall->getArg(format_idx)->getLocStart(), 1036 diag::warn_printf_nonliteral) 1037 << OrigFormatExpr->getSourceRange(); 1038} 1039 1040namespace { 1041class CheckPrintfHandler : public analyze_printf::FormatStringHandler { 1042 Sema &S; 1043 const StringLiteral *FExpr; 1044 const Expr *OrigFormatExpr; 1045 unsigned NumConversions; 1046 const unsigned NumDataArgs; 1047 const bool IsObjCLiteral; 1048 const char *Beg; // Start of format string. 1049 const bool HasVAListArg; 1050 const CallExpr *TheCall; 1051 unsigned FormatIdx; 1052public: 1053 CheckPrintfHandler(Sema &s, const StringLiteral *fexpr, 1054 const Expr *origFormatExpr, 1055 unsigned numDataArgs, bool isObjCLiteral, 1056 const char *beg, bool hasVAListArg, 1057 const CallExpr *theCall, unsigned formatIdx) 1058 : S(s), FExpr(fexpr), OrigFormatExpr(origFormatExpr), 1059 NumConversions(0), NumDataArgs(numDataArgs), 1060 IsObjCLiteral(isObjCLiteral), Beg(beg), 1061 HasVAListArg(hasVAListArg), 1062 TheCall(theCall), FormatIdx(formatIdx) {} 1063 1064 void DoneProcessing(); 1065 1066 void HandleIncompleteFormatSpecifier(const char *startSpecifier, 1067 unsigned specifierLen); 1068 1069 void 1070 HandleInvalidConversionSpecifier(const analyze_printf::FormatSpecifier &FS, 1071 const char *startSpecifier, 1072 unsigned specifierLen); 1073 1074 void HandleNullChar(const char *nullCharacter); 1075 1076 bool HandleFormatSpecifier(const analyze_printf::FormatSpecifier &FS, 1077 const char *startSpecifier, 1078 unsigned specifierLen); 1079private: 1080 SourceRange getFormatStringRange(); 1081 SourceRange getFormatSpecifierRange(const char *startSpecifier, 1082 unsigned specifierLen); 1083 SourceLocation getLocationOfByte(const char *x); 1084 1085 bool HandleAmount(const analyze_printf::OptionalAmount &Amt, 1086 unsigned MissingArgDiag, unsigned BadTypeDiag, 1087 const char *startSpecifier, unsigned specifierLen); 1088 void HandleFlags(const analyze_printf::FormatSpecifier &FS, 1089 llvm::StringRef flag, llvm::StringRef cspec, 1090 const char *startSpecifier, unsigned specifierLen); 1091 1092 const Expr *getDataArg(unsigned i) const; 1093}; 1094} 1095 1096SourceRange CheckPrintfHandler::getFormatStringRange() { 1097 return OrigFormatExpr->getSourceRange(); 1098} 1099 1100SourceRange CheckPrintfHandler:: 1101getFormatSpecifierRange(const char *startSpecifier, unsigned specifierLen) { 1102 return SourceRange(getLocationOfByte(startSpecifier), 1103 getLocationOfByte(startSpecifier+specifierLen-1)); 1104} 1105 1106SourceLocation CheckPrintfHandler::getLocationOfByte(const char *x) { 1107 return S.getLocationOfStringLiteralByte(FExpr, x - Beg); 1108} 1109 1110void CheckPrintfHandler:: 1111HandleIncompleteFormatSpecifier(const char *startSpecifier, 1112 unsigned specifierLen) { 1113 SourceLocation Loc = getLocationOfByte(startSpecifier); 1114 S.Diag(Loc, diag::warn_printf_incomplete_specifier) 1115 << getFormatSpecifierRange(startSpecifier, specifierLen); 1116} 1117 1118void CheckPrintfHandler:: 1119HandleInvalidConversionSpecifier(const analyze_printf::FormatSpecifier &FS, 1120 const char *startSpecifier, 1121 unsigned specifierLen) { 1122 1123 ++NumConversions; 1124 const analyze_printf::ConversionSpecifier &CS = 1125 FS.getConversionSpecifier(); 1126 SourceLocation Loc = getLocationOfByte(CS.getStart()); 1127 S.Diag(Loc, diag::warn_printf_invalid_conversion) 1128 << llvm::StringRef(CS.getStart(), CS.getLength()) 1129 << getFormatSpecifierRange(startSpecifier, specifierLen); 1130} 1131 1132void CheckPrintfHandler::HandleNullChar(const char *nullCharacter) { 1133 // The presence of a null character is likely an error. 1134 S.Diag(getLocationOfByte(nullCharacter), 1135 diag::warn_printf_format_string_contains_null_char) 1136 << getFormatStringRange(); 1137} 1138 1139const Expr *CheckPrintfHandler::getDataArg(unsigned i) const { 1140 return TheCall->getArg(FormatIdx + i); 1141} 1142 1143 1144 1145void CheckPrintfHandler::HandleFlags(const analyze_printf::FormatSpecifier &FS, 1146 llvm::StringRef flag, 1147 llvm::StringRef cspec, 1148 const char *startSpecifier, 1149 unsigned specifierLen) { 1150 const analyze_printf::ConversionSpecifier &CS = FS.getConversionSpecifier(); 1151 S.Diag(getLocationOfByte(CS.getStart()), diag::warn_printf_nonsensical_flag) 1152 << flag << cspec << getFormatSpecifierRange(startSpecifier, specifierLen); 1153} 1154 1155bool 1156CheckPrintfHandler::HandleAmount(const analyze_printf::OptionalAmount &Amt, 1157 unsigned MissingArgDiag, 1158 unsigned BadTypeDiag, 1159 const char *startSpecifier, 1160 unsigned specifierLen) { 1161 1162 if (Amt.hasDataArgument()) { 1163 ++NumConversions; 1164 if (!HasVAListArg) { 1165 if (NumConversions > NumDataArgs) { 1166 S.Diag(getLocationOfByte(Amt.getStart()), MissingArgDiag) 1167 << getFormatSpecifierRange(startSpecifier, specifierLen); 1168 // Don't do any more checking. We will just emit 1169 // spurious errors. 1170 return false; 1171 } 1172 1173 // Type check the data argument. It should be an 'int'. 1174 // Although not in conformance with C99, we also allow the argument to be 1175 // an 'unsigned int' as that is a reasonably safe case. GCC also 1176 // doesn't emit a warning for that case. 1177 const Expr *Arg = getDataArg(NumConversions); 1178 QualType T = Arg->getType(); 1179 1180 const analyze_printf::ArgTypeResult &ATR = Amt.getArgType(S.Context); 1181 assert(ATR.isValid()); 1182 1183 if (!ATR.matchesType(S.Context, T)) { 1184 S.Diag(getLocationOfByte(Amt.getStart()), BadTypeDiag) 1185 << ATR.getRepresentativeType(S.Context) << T 1186 << getFormatSpecifierRange(startSpecifier, specifierLen) 1187 << Arg->getSourceRange(); 1188 // Don't do any more checking. We will just emit 1189 // spurious errors. 1190 return false; 1191 } 1192 } 1193 } 1194 return true; 1195} 1196 1197bool 1198CheckPrintfHandler::HandleFormatSpecifier(const analyze_printf::FormatSpecifier 1199 &FS, 1200 const char *startSpecifier, 1201 unsigned specifierLen) { 1202 1203 using namespace analyze_printf; 1204 const ConversionSpecifier &CS = FS.getConversionSpecifier(); 1205 1206 // First check if the field width, precision, and conversion specifier 1207 // have matching data arguments. 1208 if (!HandleAmount(FS.getFieldWidth(), 1209 diag::warn_printf_asterisk_width_missing_arg, 1210 diag::warn_printf_asterisk_width_wrong_type, 1211 startSpecifier, specifierLen)) { 1212 return false; 1213 } 1214 1215 if (!HandleAmount(FS.getPrecision(), 1216 diag::warn_printf_asterisk_precision_missing_arg, 1217 diag::warn_printf_asterisk_precision_wrong_type, 1218 startSpecifier, specifierLen)) { 1219 return false; 1220 } 1221 1222 // Check for using an Objective-C specific conversion specifier 1223 // in a non-ObjC literal. 1224 if (!IsObjCLiteral && CS.isObjCArg()) { 1225 HandleInvalidConversionSpecifier(FS, startSpecifier, specifierLen); 1226 1227 // Continue checking the other format specifiers. 1228 return true; 1229 } 1230 1231 if (!CS.consumesDataArgument()) { 1232 // FIXME: Technically specifying a precision or field width here 1233 // makes no sense. Worth issuing a warning at some point. 1234 return true; 1235 } 1236 1237 ++NumConversions; 1238 1239 // Are we using '%n'? Issue a warning about this being 1240 // a possible security issue. 1241 if (CS.getKind() == ConversionSpecifier::OutIntPtrArg) { 1242 S.Diag(getLocationOfByte(CS.getStart()), diag::warn_printf_write_back) 1243 << getFormatSpecifierRange(startSpecifier, specifierLen); 1244 // Continue checking the other format specifiers. 1245 return true; 1246 } 1247 1248 if (CS.getKind() == ConversionSpecifier::VoidPtrArg) { 1249 if (FS.getPrecision().getHowSpecified() != OptionalAmount::NotSpecified) 1250 S.Diag(getLocationOfByte(CS.getStart()), 1251 diag::warn_printf_nonsensical_precision) 1252 << CS.getCharacters() 1253 << getFormatSpecifierRange(startSpecifier, specifierLen); 1254 } 1255 if (CS.getKind() == ConversionSpecifier::VoidPtrArg || 1256 CS.getKind() == ConversionSpecifier::CStrArg) { 1257 // FIXME: Instead of using "0", "+", etc., eventually get them from 1258 // the FormatSpecifier. 1259 if (FS.hasLeadingZeros()) 1260 HandleFlags(FS, "0", CS.getCharacters(), startSpecifier, specifierLen); 1261 if (FS.hasPlusPrefix()) 1262 HandleFlags(FS, "+", CS.getCharacters(), startSpecifier, specifierLen); 1263 if (FS.hasSpacePrefix()) 1264 HandleFlags(FS, " ", CS.getCharacters(), startSpecifier, specifierLen); 1265 } 1266 1267 // The remaining checks depend on the data arguments. 1268 if (HasVAListArg) 1269 return true; 1270 1271 if (NumConversions > NumDataArgs) { 1272 S.Diag(getLocationOfByte(CS.getStart()), 1273 diag::warn_printf_insufficient_data_args) 1274 << getFormatSpecifierRange(startSpecifier, specifierLen); 1275 // Don't do any more checking. 1276 return false; 1277 } 1278 1279 // Now type check the data expression that matches the 1280 // format specifier. 1281 const Expr *Ex = getDataArg(NumConversions); 1282 const analyze_printf::ArgTypeResult &ATR = FS.getArgType(S.Context); 1283 if (ATR.isValid() && !ATR.matchesType(S.Context, Ex->getType())) { 1284 // Check if we didn't match because of an implicit cast from a 'char' 1285 // or 'short' to an 'int'. This is done because printf is a varargs 1286 // function. 1287 if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Ex)) 1288 if (ICE->getType() == S.Context.IntTy) 1289 if (ATR.matchesType(S.Context, ICE->getSubExpr()->getType())) 1290 return true; 1291 1292 S.Diag(getLocationOfByte(CS.getStart()), 1293 diag::warn_printf_conversion_argument_type_mismatch) 1294 << ATR.getRepresentativeType(S.Context) << Ex->getType() 1295 << getFormatSpecifierRange(startSpecifier, specifierLen) 1296 << Ex->getSourceRange(); 1297 } 1298 1299 return true; 1300} 1301 1302void CheckPrintfHandler::DoneProcessing() { 1303 // Does the number of data arguments exceed the number of 1304 // format conversions in the format string? 1305 if (!HasVAListArg && NumConversions < NumDataArgs) 1306 S.Diag(getDataArg(NumConversions+1)->getLocStart(), 1307 diag::warn_printf_too_many_data_args) 1308 << getFormatStringRange(); 1309} 1310 1311void Sema::CheckPrintfString(const StringLiteral *FExpr, 1312 const Expr *OrigFormatExpr, 1313 const CallExpr *TheCall, bool HasVAListArg, 1314 unsigned format_idx, unsigned firstDataArg) { 1315 1316 // CHECK: is the format string a wide literal? 1317 if (FExpr->isWide()) { 1318 Diag(FExpr->getLocStart(), 1319 diag::warn_printf_format_string_is_wide_literal) 1320 << OrigFormatExpr->getSourceRange(); 1321 return; 1322 } 1323 1324 // Str - The format string. NOTE: this is NOT null-terminated! 1325 const char *Str = FExpr->getStrData(); 1326 1327 // CHECK: empty format string? 1328 unsigned StrLen = FExpr->getByteLength(); 1329 1330 if (StrLen == 0) { 1331 Diag(FExpr->getLocStart(), diag::warn_printf_empty_format_string) 1332 << OrigFormatExpr->getSourceRange(); 1333 return; 1334 } 1335 1336 CheckPrintfHandler H(*this, FExpr, OrigFormatExpr, 1337 TheCall->getNumArgs() - firstDataArg, 1338 isa<ObjCStringLiteral>(OrigFormatExpr), Str, 1339 HasVAListArg, TheCall, format_idx); 1340 1341 if (!analyze_printf::ParseFormatString(H, Str, Str + StrLen)) 1342 H.DoneProcessing(); 1343} 1344 1345//===--- CHECK: Return Address of Stack Variable --------------------------===// 1346 1347static DeclRefExpr* EvalVal(Expr *E); 1348static DeclRefExpr* EvalAddr(Expr* E); 1349 1350/// CheckReturnStackAddr - Check if a return statement returns the address 1351/// of a stack variable. 1352void 1353Sema::CheckReturnStackAddr(Expr *RetValExp, QualType lhsType, 1354 SourceLocation ReturnLoc) { 1355 1356 // Perform checking for returned stack addresses. 1357 if (lhsType->isPointerType() || lhsType->isBlockPointerType()) { 1358 if (DeclRefExpr *DR = EvalAddr(RetValExp)) 1359 Diag(DR->getLocStart(), diag::warn_ret_stack_addr) 1360 << DR->getDecl()->getDeclName() << RetValExp->getSourceRange(); 1361 1362 // Skip over implicit cast expressions when checking for block expressions. 1363 RetValExp = RetValExp->IgnoreParenCasts(); 1364 1365 if (BlockExpr *C = dyn_cast<BlockExpr>(RetValExp)) 1366 if (C->hasBlockDeclRefExprs()) 1367 Diag(C->getLocStart(), diag::err_ret_local_block) 1368 << C->getSourceRange(); 1369 1370 if (AddrLabelExpr *ALE = dyn_cast<AddrLabelExpr>(RetValExp)) 1371 Diag(ALE->getLocStart(), diag::warn_ret_addr_label) 1372 << ALE->getSourceRange(); 1373 1374 } else if (lhsType->isReferenceType()) { 1375 // Perform checking for stack values returned by reference. 1376 // Check for a reference to the stack 1377 if (DeclRefExpr *DR = EvalVal(RetValExp)) 1378 Diag(DR->getLocStart(), diag::warn_ret_stack_ref) 1379 << DR->getDecl()->getDeclName() << RetValExp->getSourceRange(); 1380 } 1381} 1382 1383/// EvalAddr - EvalAddr and EvalVal are mutually recursive functions that 1384/// check if the expression in a return statement evaluates to an address 1385/// to a location on the stack. The recursion is used to traverse the 1386/// AST of the return expression, with recursion backtracking when we 1387/// encounter a subexpression that (1) clearly does not lead to the address 1388/// of a stack variable or (2) is something we cannot determine leads to 1389/// the address of a stack variable based on such local checking. 1390/// 1391/// EvalAddr processes expressions that are pointers that are used as 1392/// references (and not L-values). EvalVal handles all other values. 1393/// At the base case of the recursion is a check for a DeclRefExpr* in 1394/// the refers to a stack variable. 1395/// 1396/// This implementation handles: 1397/// 1398/// * pointer-to-pointer casts 1399/// * implicit conversions from array references to pointers 1400/// * taking the address of fields 1401/// * arbitrary interplay between "&" and "*" operators 1402/// * pointer arithmetic from an address of a stack variable 1403/// * taking the address of an array element where the array is on the stack 1404static DeclRefExpr* EvalAddr(Expr *E) { 1405 // We should only be called for evaluating pointer expressions. 1406 assert((E->getType()->isAnyPointerType() || 1407 E->getType()->isBlockPointerType() || 1408 E->getType()->isObjCQualifiedIdType()) && 1409 "EvalAddr only works on pointers"); 1410 1411 // Our "symbolic interpreter" is just a dispatch off the currently 1412 // viewed AST node. We then recursively traverse the AST by calling 1413 // EvalAddr and EvalVal appropriately. 1414 switch (E->getStmtClass()) { 1415 case Stmt::ParenExprClass: 1416 // Ignore parentheses. 1417 return EvalAddr(cast<ParenExpr>(E)->getSubExpr()); 1418 1419 case Stmt::UnaryOperatorClass: { 1420 // The only unary operator that make sense to handle here 1421 // is AddrOf. All others don't make sense as pointers. 1422 UnaryOperator *U = cast<UnaryOperator>(E); 1423 1424 if (U->getOpcode() == UnaryOperator::AddrOf) 1425 return EvalVal(U->getSubExpr()); 1426 else 1427 return NULL; 1428 } 1429 1430 case Stmt::BinaryOperatorClass: { 1431 // Handle pointer arithmetic. All other binary operators are not valid 1432 // in this context. 1433 BinaryOperator *B = cast<BinaryOperator>(E); 1434 BinaryOperator::Opcode op = B->getOpcode(); 1435 1436 if (op != BinaryOperator::Add && op != BinaryOperator::Sub) 1437 return NULL; 1438 1439 Expr *Base = B->getLHS(); 1440 1441 // Determine which argument is the real pointer base. It could be 1442 // the RHS argument instead of the LHS. 1443 if (!Base->getType()->isPointerType()) Base = B->getRHS(); 1444 1445 assert (Base->getType()->isPointerType()); 1446 return EvalAddr(Base); 1447 } 1448 1449 // For conditional operators we need to see if either the LHS or RHS are 1450 // valid DeclRefExpr*s. If one of them is valid, we return it. 1451 case Stmt::ConditionalOperatorClass: { 1452 ConditionalOperator *C = cast<ConditionalOperator>(E); 1453 1454 // Handle the GNU extension for missing LHS. 1455 if (Expr *lhsExpr = C->getLHS()) 1456 if (DeclRefExpr* LHS = EvalAddr(lhsExpr)) 1457 return LHS; 1458 1459 return EvalAddr(C->getRHS()); 1460 } 1461 1462 // For casts, we need to handle conversions from arrays to 1463 // pointer values, and pointer-to-pointer conversions. 1464 case Stmt::ImplicitCastExprClass: 1465 case Stmt::CStyleCastExprClass: 1466 case Stmt::CXXFunctionalCastExprClass: { 1467 Expr* SubExpr = cast<CastExpr>(E)->getSubExpr(); 1468 QualType T = SubExpr->getType(); 1469 1470 if (SubExpr->getType()->isPointerType() || 1471 SubExpr->getType()->isBlockPointerType() || 1472 SubExpr->getType()->isObjCQualifiedIdType()) 1473 return EvalAddr(SubExpr); 1474 else if (T->isArrayType()) 1475 return EvalVal(SubExpr); 1476 else 1477 return 0; 1478 } 1479 1480 // C++ casts. For dynamic casts, static casts, and const casts, we 1481 // are always converting from a pointer-to-pointer, so we just blow 1482 // through the cast. In the case the dynamic cast doesn't fail (and 1483 // return NULL), we take the conservative route and report cases 1484 // where we return the address of a stack variable. For Reinterpre 1485 // FIXME: The comment about is wrong; we're not always converting 1486 // from pointer to pointer. I'm guessing that this code should also 1487 // handle references to objects. 1488 case Stmt::CXXStaticCastExprClass: 1489 case Stmt::CXXDynamicCastExprClass: 1490 case Stmt::CXXConstCastExprClass: 1491 case Stmt::CXXReinterpretCastExprClass: { 1492 Expr *S = cast<CXXNamedCastExpr>(E)->getSubExpr(); 1493 if (S->getType()->isPointerType() || S->getType()->isBlockPointerType()) 1494 return EvalAddr(S); 1495 else 1496 return NULL; 1497 } 1498 1499 // Everything else: we simply don't reason about them. 1500 default: 1501 return NULL; 1502 } 1503} 1504 1505 1506/// EvalVal - This function is complements EvalAddr in the mutual recursion. 1507/// See the comments for EvalAddr for more details. 1508static DeclRefExpr* EvalVal(Expr *E) { 1509 1510 // We should only be called for evaluating non-pointer expressions, or 1511 // expressions with a pointer type that are not used as references but instead 1512 // are l-values (e.g., DeclRefExpr with a pointer type). 1513 1514 // Our "symbolic interpreter" is just a dispatch off the currently 1515 // viewed AST node. We then recursively traverse the AST by calling 1516 // EvalAddr and EvalVal appropriately. 1517 switch (E->getStmtClass()) { 1518 case Stmt::DeclRefExprClass: { 1519 // DeclRefExpr: the base case. When we hit a DeclRefExpr we are looking 1520 // at code that refers to a variable's name. We check if it has local 1521 // storage within the function, and if so, return the expression. 1522 DeclRefExpr *DR = cast<DeclRefExpr>(E); 1523 1524 if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl())) 1525 if (V->hasLocalStorage() && !V->getType()->isReferenceType()) return DR; 1526 1527 return NULL; 1528 } 1529 1530 case Stmt::ParenExprClass: 1531 // Ignore parentheses. 1532 return EvalVal(cast<ParenExpr>(E)->getSubExpr()); 1533 1534 case Stmt::UnaryOperatorClass: { 1535 // The only unary operator that make sense to handle here 1536 // is Deref. All others don't resolve to a "name." This includes 1537 // handling all sorts of rvalues passed to a unary operator. 1538 UnaryOperator *U = cast<UnaryOperator>(E); 1539 1540 if (U->getOpcode() == UnaryOperator::Deref) 1541 return EvalAddr(U->getSubExpr()); 1542 1543 return NULL; 1544 } 1545 1546 case Stmt::ArraySubscriptExprClass: { 1547 // Array subscripts are potential references to data on the stack. We 1548 // retrieve the DeclRefExpr* for the array variable if it indeed 1549 // has local storage. 1550 return EvalAddr(cast<ArraySubscriptExpr>(E)->getBase()); 1551 } 1552 1553 case Stmt::ConditionalOperatorClass: { 1554 // For conditional operators we need to see if either the LHS or RHS are 1555 // non-NULL DeclRefExpr's. If one is non-NULL, we return it. 1556 ConditionalOperator *C = cast<ConditionalOperator>(E); 1557 1558 // Handle the GNU extension for missing LHS. 1559 if (Expr *lhsExpr = C->getLHS()) 1560 if (DeclRefExpr *LHS = EvalVal(lhsExpr)) 1561 return LHS; 1562 1563 return EvalVal(C->getRHS()); 1564 } 1565 1566 // Accesses to members are potential references to data on the stack. 1567 case Stmt::MemberExprClass: { 1568 MemberExpr *M = cast<MemberExpr>(E); 1569 1570 // Check for indirect access. We only want direct field accesses. 1571 if (!M->isArrow()) 1572 return EvalVal(M->getBase()); 1573 else 1574 return NULL; 1575 } 1576 1577 // Everything else: we simply don't reason about them. 1578 default: 1579 return NULL; 1580 } 1581} 1582 1583//===--- CHECK: Floating-Point comparisons (-Wfloat-equal) ---------------===// 1584 1585/// Check for comparisons of floating point operands using != and ==. 1586/// Issue a warning if these are no self-comparisons, as they are not likely 1587/// to do what the programmer intended. 1588void Sema::CheckFloatComparison(SourceLocation loc, Expr* lex, Expr *rex) { 1589 bool EmitWarning = true; 1590 1591 Expr* LeftExprSansParen = lex->IgnoreParens(); 1592 Expr* RightExprSansParen = rex->IgnoreParens(); 1593 1594 // Special case: check for x == x (which is OK). 1595 // Do not emit warnings for such cases. 1596 if (DeclRefExpr* DRL = dyn_cast<DeclRefExpr>(LeftExprSansParen)) 1597 if (DeclRefExpr* DRR = dyn_cast<DeclRefExpr>(RightExprSansParen)) 1598 if (DRL->getDecl() == DRR->getDecl()) 1599 EmitWarning = false; 1600 1601 1602 // Special case: check for comparisons against literals that can be exactly 1603 // represented by APFloat. In such cases, do not emit a warning. This 1604 // is a heuristic: often comparison against such literals are used to 1605 // detect if a value in a variable has not changed. This clearly can 1606 // lead to false negatives. 1607 if (EmitWarning) { 1608 if (FloatingLiteral* FLL = dyn_cast<FloatingLiteral>(LeftExprSansParen)) { 1609 if (FLL->isExact()) 1610 EmitWarning = false; 1611 } else 1612 if (FloatingLiteral* FLR = dyn_cast<FloatingLiteral>(RightExprSansParen)){ 1613 if (FLR->isExact()) 1614 EmitWarning = false; 1615 } 1616 } 1617 1618 // Check for comparisons with builtin types. 1619 if (EmitWarning) 1620 if (CallExpr* CL = dyn_cast<CallExpr>(LeftExprSansParen)) 1621 if (CL->isBuiltinCall(Context)) 1622 EmitWarning = false; 1623 1624 if (EmitWarning) 1625 if (CallExpr* CR = dyn_cast<CallExpr>(RightExprSansParen)) 1626 if (CR->isBuiltinCall(Context)) 1627 EmitWarning = false; 1628 1629 // Emit the diagnostic. 1630 if (EmitWarning) 1631 Diag(loc, diag::warn_floatingpoint_eq) 1632 << lex->getSourceRange() << rex->getSourceRange(); 1633} 1634 1635//===--- CHECK: Integer mixed-sign comparisons (-Wsign-compare) --------===// 1636//===--- CHECK: Lossy implicit conversions (-Wconversion) --------------===// 1637 1638namespace { 1639 1640/// Structure recording the 'active' range of an integer-valued 1641/// expression. 1642struct IntRange { 1643 /// The number of bits active in the int. 1644 unsigned Width; 1645 1646 /// True if the int is known not to have negative values. 1647 bool NonNegative; 1648 1649 IntRange() {} 1650 IntRange(unsigned Width, bool NonNegative) 1651 : Width(Width), NonNegative(NonNegative) 1652 {} 1653 1654 // Returns the range of the bool type. 1655 static IntRange forBoolType() { 1656 return IntRange(1, true); 1657 } 1658 1659 // Returns the range of an integral type. 1660 static IntRange forType(ASTContext &C, QualType T) { 1661 return forCanonicalType(C, T->getCanonicalTypeInternal().getTypePtr()); 1662 } 1663 1664 // Returns the range of an integeral type based on its canonical 1665 // representation. 1666 static IntRange forCanonicalType(ASTContext &C, const Type *T) { 1667 assert(T->isCanonicalUnqualified()); 1668 1669 if (const VectorType *VT = dyn_cast<VectorType>(T)) 1670 T = VT->getElementType().getTypePtr(); 1671 if (const ComplexType *CT = dyn_cast<ComplexType>(T)) 1672 T = CT->getElementType().getTypePtr(); 1673 if (const EnumType *ET = dyn_cast<EnumType>(T)) 1674 T = ET->getDecl()->getIntegerType().getTypePtr(); 1675 1676 const BuiltinType *BT = cast<BuiltinType>(T); 1677 assert(BT->isInteger()); 1678 1679 return IntRange(C.getIntWidth(QualType(T, 0)), BT->isUnsignedInteger()); 1680 } 1681 1682 // Returns the supremum of two ranges: i.e. their conservative merge. 1683 static IntRange join(const IntRange &L, const IntRange &R) { 1684 return IntRange(std::max(L.Width, R.Width), 1685 L.NonNegative && R.NonNegative); 1686 } 1687 1688 // Returns the infinum of two ranges: i.e. their aggressive merge. 1689 static IntRange meet(const IntRange &L, const IntRange &R) { 1690 return IntRange(std::min(L.Width, R.Width), 1691 L.NonNegative || R.NonNegative); 1692 } 1693}; 1694 1695IntRange GetValueRange(ASTContext &C, llvm::APSInt &value, unsigned MaxWidth) { 1696 if (value.isSigned() && value.isNegative()) 1697 return IntRange(value.getMinSignedBits(), false); 1698 1699 if (value.getBitWidth() > MaxWidth) 1700 value.trunc(MaxWidth); 1701 1702 // isNonNegative() just checks the sign bit without considering 1703 // signedness. 1704 return IntRange(value.getActiveBits(), true); 1705} 1706 1707IntRange GetValueRange(ASTContext &C, APValue &result, QualType Ty, 1708 unsigned MaxWidth) { 1709 if (result.isInt()) 1710 return GetValueRange(C, result.getInt(), MaxWidth); 1711 1712 if (result.isVector()) { 1713 IntRange R = GetValueRange(C, result.getVectorElt(0), Ty, MaxWidth); 1714 for (unsigned i = 1, e = result.getVectorLength(); i != e; ++i) { 1715 IntRange El = GetValueRange(C, result.getVectorElt(i), Ty, MaxWidth); 1716 R = IntRange::join(R, El); 1717 } 1718 return R; 1719 } 1720 1721 if (result.isComplexInt()) { 1722 IntRange R = GetValueRange(C, result.getComplexIntReal(), MaxWidth); 1723 IntRange I = GetValueRange(C, result.getComplexIntImag(), MaxWidth); 1724 return IntRange::join(R, I); 1725 } 1726 1727 // This can happen with lossless casts to intptr_t of "based" lvalues. 1728 // Assume it might use arbitrary bits. 1729 // FIXME: The only reason we need to pass the type in here is to get 1730 // the sign right on this one case. It would be nice if APValue 1731 // preserved this. 1732 assert(result.isLValue()); 1733 return IntRange(MaxWidth, Ty->isUnsignedIntegerType()); 1734} 1735 1736/// Pseudo-evaluate the given integer expression, estimating the 1737/// range of values it might take. 1738/// 1739/// \param MaxWidth - the width to which the value will be truncated 1740IntRange GetExprRange(ASTContext &C, Expr *E, unsigned MaxWidth) { 1741 E = E->IgnoreParens(); 1742 1743 // Try a full evaluation first. 1744 Expr::EvalResult result; 1745 if (E->Evaluate(result, C)) 1746 return GetValueRange(C, result.Val, E->getType(), MaxWidth); 1747 1748 // I think we only want to look through implicit casts here; if the 1749 // user has an explicit widening cast, we should treat the value as 1750 // being of the new, wider type. 1751 if (ImplicitCastExpr *CE = dyn_cast<ImplicitCastExpr>(E)) { 1752 if (CE->getCastKind() == CastExpr::CK_NoOp) 1753 return GetExprRange(C, CE->getSubExpr(), MaxWidth); 1754 1755 IntRange OutputTypeRange = IntRange::forType(C, CE->getType()); 1756 1757 bool isIntegerCast = (CE->getCastKind() == CastExpr::CK_IntegralCast); 1758 if (!isIntegerCast && CE->getCastKind() == CastExpr::CK_Unknown) 1759 isIntegerCast = CE->getSubExpr()->getType()->isIntegerType(); 1760 1761 // Assume that non-integer casts can span the full range of the type. 1762 if (!isIntegerCast) 1763 return OutputTypeRange; 1764 1765 IntRange SubRange 1766 = GetExprRange(C, CE->getSubExpr(), 1767 std::min(MaxWidth, OutputTypeRange.Width)); 1768 1769 // Bail out if the subexpr's range is as wide as the cast type. 1770 if (SubRange.Width >= OutputTypeRange.Width) 1771 return OutputTypeRange; 1772 1773 // Otherwise, we take the smaller width, and we're non-negative if 1774 // either the output type or the subexpr is. 1775 return IntRange(SubRange.Width, 1776 SubRange.NonNegative || OutputTypeRange.NonNegative); 1777 } 1778 1779 if (ConditionalOperator *CO = dyn_cast<ConditionalOperator>(E)) { 1780 // If we can fold the condition, just take that operand. 1781 bool CondResult; 1782 if (CO->getCond()->EvaluateAsBooleanCondition(CondResult, C)) 1783 return GetExprRange(C, CondResult ? CO->getTrueExpr() 1784 : CO->getFalseExpr(), 1785 MaxWidth); 1786 1787 // Otherwise, conservatively merge. 1788 IntRange L = GetExprRange(C, CO->getTrueExpr(), MaxWidth); 1789 IntRange R = GetExprRange(C, CO->getFalseExpr(), MaxWidth); 1790 return IntRange::join(L, R); 1791 } 1792 1793 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) { 1794 switch (BO->getOpcode()) { 1795 1796 // Boolean-valued operations are single-bit and positive. 1797 case BinaryOperator::LAnd: 1798 case BinaryOperator::LOr: 1799 case BinaryOperator::LT: 1800 case BinaryOperator::GT: 1801 case BinaryOperator::LE: 1802 case BinaryOperator::GE: 1803 case BinaryOperator::EQ: 1804 case BinaryOperator::NE: 1805 return IntRange::forBoolType(); 1806 1807 // Operations with opaque sources are black-listed. 1808 case BinaryOperator::PtrMemD: 1809 case BinaryOperator::PtrMemI: 1810 return IntRange::forType(C, E->getType()); 1811 1812 // Bitwise-and uses the *infinum* of the two source ranges. 1813 case BinaryOperator::And: 1814 return IntRange::meet(GetExprRange(C, BO->getLHS(), MaxWidth), 1815 GetExprRange(C, BO->getRHS(), MaxWidth)); 1816 1817 // Left shift gets black-listed based on a judgement call. 1818 case BinaryOperator::Shl: 1819 return IntRange::forType(C, E->getType()); 1820 1821 // Right shift by a constant can narrow its left argument. 1822 case BinaryOperator::Shr: { 1823 IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth); 1824 1825 // If the shift amount is a positive constant, drop the width by 1826 // that much. 1827 llvm::APSInt shift; 1828 if (BO->getRHS()->isIntegerConstantExpr(shift, C) && 1829 shift.isNonNegative()) { 1830 unsigned zext = shift.getZExtValue(); 1831 if (zext >= L.Width) 1832 L.Width = (L.NonNegative ? 0 : 1); 1833 else 1834 L.Width -= zext; 1835 } 1836 1837 return L; 1838 } 1839 1840 // Comma acts as its right operand. 1841 case BinaryOperator::Comma: 1842 return GetExprRange(C, BO->getRHS(), MaxWidth); 1843 1844 // Black-list pointer subtractions. 1845 case BinaryOperator::Sub: 1846 if (BO->getLHS()->getType()->isPointerType()) 1847 return IntRange::forType(C, E->getType()); 1848 // fallthrough 1849 1850 default: 1851 break; 1852 } 1853 1854 // Treat every other operator as if it were closed on the 1855 // narrowest type that encompasses both operands. 1856 IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth); 1857 IntRange R = GetExprRange(C, BO->getRHS(), MaxWidth); 1858 return IntRange::join(L, R); 1859 } 1860 1861 if (UnaryOperator *UO = dyn_cast<UnaryOperator>(E)) { 1862 switch (UO->getOpcode()) { 1863 // Boolean-valued operations are white-listed. 1864 case UnaryOperator::LNot: 1865 return IntRange::forBoolType(); 1866 1867 // Operations with opaque sources are black-listed. 1868 case UnaryOperator::Deref: 1869 case UnaryOperator::AddrOf: // should be impossible 1870 case UnaryOperator::OffsetOf: 1871 return IntRange::forType(C, E->getType()); 1872 1873 default: 1874 return GetExprRange(C, UO->getSubExpr(), MaxWidth); 1875 } 1876 } 1877 1878 FieldDecl *BitField = E->getBitField(); 1879 if (BitField) { 1880 llvm::APSInt BitWidthAP = BitField->getBitWidth()->EvaluateAsInt(C); 1881 unsigned BitWidth = BitWidthAP.getZExtValue(); 1882 1883 return IntRange(BitWidth, BitField->getType()->isUnsignedIntegerType()); 1884 } 1885 1886 return IntRange::forType(C, E->getType()); 1887} 1888 1889/// Checks whether the given value, which currently has the given 1890/// source semantics, has the same value when coerced through the 1891/// target semantics. 1892bool IsSameFloatAfterCast(const llvm::APFloat &value, 1893 const llvm::fltSemantics &Src, 1894 const llvm::fltSemantics &Tgt) { 1895 llvm::APFloat truncated = value; 1896 1897 bool ignored; 1898 truncated.convert(Src, llvm::APFloat::rmNearestTiesToEven, &ignored); 1899 truncated.convert(Tgt, llvm::APFloat::rmNearestTiesToEven, &ignored); 1900 1901 return truncated.bitwiseIsEqual(value); 1902} 1903 1904/// Checks whether the given value, which currently has the given 1905/// source semantics, has the same value when coerced through the 1906/// target semantics. 1907/// 1908/// The value might be a vector of floats (or a complex number). 1909bool IsSameFloatAfterCast(const APValue &value, 1910 const llvm::fltSemantics &Src, 1911 const llvm::fltSemantics &Tgt) { 1912 if (value.isFloat()) 1913 return IsSameFloatAfterCast(value.getFloat(), Src, Tgt); 1914 1915 if (value.isVector()) { 1916 for (unsigned i = 0, e = value.getVectorLength(); i != e; ++i) 1917 if (!IsSameFloatAfterCast(value.getVectorElt(i), Src, Tgt)) 1918 return false; 1919 return true; 1920 } 1921 1922 assert(value.isComplexFloat()); 1923 return (IsSameFloatAfterCast(value.getComplexFloatReal(), Src, Tgt) && 1924 IsSameFloatAfterCast(value.getComplexFloatImag(), Src, Tgt)); 1925} 1926 1927} // end anonymous namespace 1928 1929/// \brief Implements -Wsign-compare. 1930/// 1931/// \param lex the left-hand expression 1932/// \param rex the right-hand expression 1933/// \param OpLoc the location of the joining operator 1934/// \param Equality whether this is an "equality-like" join, which 1935/// suppresses the warning in some cases 1936void Sema::CheckSignCompare(Expr *lex, Expr *rex, SourceLocation OpLoc, 1937 const PartialDiagnostic &PD, bool Equality) { 1938 // Don't warn if we're in an unevaluated context. 1939 if (ExprEvalContexts.back().Context == Unevaluated) 1940 return; 1941 1942 // If either expression is value-dependent, don't warn. We'll get another 1943 // chance at instantiation time. 1944 if (lex->isValueDependent() || rex->isValueDependent()) 1945 return; 1946 1947 QualType lt = lex->getType(), rt = rex->getType(); 1948 1949 // Only warn if both operands are integral. 1950 if (!lt->isIntegerType() || !rt->isIntegerType()) 1951 return; 1952 1953 // In C, the width of a bitfield determines its type, and the 1954 // declared type only contributes the signedness. This duplicates 1955 // the work that will later be done by UsualUnaryConversions. 1956 // Eventually, this check will be reorganized in a way that avoids 1957 // this duplication. 1958 if (!getLangOptions().CPlusPlus) { 1959 QualType tmp; 1960 tmp = Context.isPromotableBitField(lex); 1961 if (!tmp.isNull()) lt = tmp; 1962 tmp = Context.isPromotableBitField(rex); 1963 if (!tmp.isNull()) rt = tmp; 1964 } 1965 1966 // The rule is that the signed operand becomes unsigned, so isolate the 1967 // signed operand. 1968 Expr *signedOperand = lex, *unsignedOperand = rex; 1969 QualType signedType = lt, unsignedType = rt; 1970 if (lt->isSignedIntegerType()) { 1971 if (rt->isSignedIntegerType()) return; 1972 } else { 1973 if (!rt->isSignedIntegerType()) return; 1974 std::swap(signedOperand, unsignedOperand); 1975 std::swap(signedType, unsignedType); 1976 } 1977 1978 unsigned unsignedWidth = Context.getIntWidth(unsignedType); 1979 unsigned signedWidth = Context.getIntWidth(signedType); 1980 1981 // If the unsigned type is strictly smaller than the signed type, 1982 // then (1) the result type will be signed and (2) the unsigned 1983 // value will fit fully within the signed type, and thus the result 1984 // of the comparison will be exact. 1985 if (signedWidth > unsignedWidth) 1986 return; 1987 1988 // Otherwise, calculate the effective ranges. 1989 IntRange signedRange = GetExprRange(Context, signedOperand, signedWidth); 1990 IntRange unsignedRange = GetExprRange(Context, unsignedOperand, unsignedWidth); 1991 1992 // We should never be unable to prove that the unsigned operand is 1993 // non-negative. 1994 assert(unsignedRange.NonNegative && "unsigned range includes negative?"); 1995 1996 // If the signed operand is non-negative, then the signed->unsigned 1997 // conversion won't change it. 1998 if (signedRange.NonNegative) 1999 return; 2000 2001 // For (in)equality comparisons, if the unsigned operand is a 2002 // constant which cannot collide with a overflowed signed operand, 2003 // then reinterpreting the signed operand as unsigned will not 2004 // change the result of the comparison. 2005 if (Equality && unsignedRange.Width < unsignedWidth) 2006 return; 2007 2008 Diag(OpLoc, PD) 2009 << lt << rt << lex->getSourceRange() << rex->getSourceRange(); 2010} 2011 2012/// Diagnose an implicit cast; purely a helper for CheckImplicitConversion. 2013static void DiagnoseImpCast(Sema &S, Expr *E, QualType T, unsigned diag) { 2014 S.Diag(E->getExprLoc(), diag) << E->getType() << T << E->getSourceRange(); 2015} 2016 2017/// Implements -Wconversion. 2018void Sema::CheckImplicitConversion(Expr *E, QualType T) { 2019 // Don't diagnose in unevaluated contexts. 2020 if (ExprEvalContexts.back().Context == Sema::Unevaluated) 2021 return; 2022 2023 // Don't diagnose for value-dependent expressions. 2024 if (E->isValueDependent()) 2025 return; 2026 2027 const Type *Source = Context.getCanonicalType(E->getType()).getTypePtr(); 2028 const Type *Target = Context.getCanonicalType(T).getTypePtr(); 2029 2030 // Never diagnose implicit casts to bool. 2031 if (Target->isSpecificBuiltinType(BuiltinType::Bool)) 2032 return; 2033 2034 // Strip vector types. 2035 if (isa<VectorType>(Source)) { 2036 if (!isa<VectorType>(Target)) 2037 return DiagnoseImpCast(*this, E, T, diag::warn_impcast_vector_scalar); 2038 2039 Source = cast<VectorType>(Source)->getElementType().getTypePtr(); 2040 Target = cast<VectorType>(Target)->getElementType().getTypePtr(); 2041 } 2042 2043 // Strip complex types. 2044 if (isa<ComplexType>(Source)) { 2045 if (!isa<ComplexType>(Target)) 2046 return DiagnoseImpCast(*this, E, T, diag::warn_impcast_complex_scalar); 2047 2048 Source = cast<ComplexType>(Source)->getElementType().getTypePtr(); 2049 Target = cast<ComplexType>(Target)->getElementType().getTypePtr(); 2050 } 2051 2052 const BuiltinType *SourceBT = dyn_cast<BuiltinType>(Source); 2053 const BuiltinType *TargetBT = dyn_cast<BuiltinType>(Target); 2054 2055 // If the source is floating point... 2056 if (SourceBT && SourceBT->isFloatingPoint()) { 2057 // ...and the target is floating point... 2058 if (TargetBT && TargetBT->isFloatingPoint()) { 2059 // ...then warn if we're dropping FP rank. 2060 2061 // Builtin FP kinds are ordered by increasing FP rank. 2062 if (SourceBT->getKind() > TargetBT->getKind()) { 2063 // Don't warn about float constants that are precisely 2064 // representable in the target type. 2065 Expr::EvalResult result; 2066 if (E->Evaluate(result, Context)) { 2067 // Value might be a float, a float vector, or a float complex. 2068 if (IsSameFloatAfterCast(result.Val, 2069 Context.getFloatTypeSemantics(QualType(TargetBT, 0)), 2070 Context.getFloatTypeSemantics(QualType(SourceBT, 0)))) 2071 return; 2072 } 2073 2074 DiagnoseImpCast(*this, E, T, diag::warn_impcast_float_precision); 2075 } 2076 return; 2077 } 2078 2079 // If the target is integral, always warn. 2080 if ((TargetBT && TargetBT->isInteger())) 2081 // TODO: don't warn for integer values? 2082 return DiagnoseImpCast(*this, E, T, diag::warn_impcast_float_integer); 2083 2084 return; 2085 } 2086 2087 if (!Source->isIntegerType() || !Target->isIntegerType()) 2088 return; 2089 2090 IntRange SourceRange = GetExprRange(Context, E, Context.getIntWidth(E->getType())); 2091 IntRange TargetRange = IntRange::forCanonicalType(Context, Target); 2092 2093 // FIXME: also signed<->unsigned? 2094 2095 if (SourceRange.Width > TargetRange.Width) { 2096 // People want to build with -Wshorten-64-to-32 and not -Wconversion 2097 // and by god we'll let them. 2098 if (SourceRange.Width == 64 && TargetRange.Width == 32) 2099 return DiagnoseImpCast(*this, E, T, diag::warn_impcast_integer_64_32); 2100 return DiagnoseImpCast(*this, E, T, diag::warn_impcast_integer_precision); 2101 } 2102 2103 return; 2104} 2105 2106// MarkLive - Mark all the blocks reachable from e as live. Returns the total 2107// number of blocks just marked live. 2108static unsigned MarkLive(CFGBlock *e, llvm::BitVector &live) { 2109 unsigned count = 0; 2110 std::queue<CFGBlock*> workq; 2111 // Prep work queue 2112 live.set(e->getBlockID()); 2113 ++count; 2114 workq.push(e); 2115 // Solve 2116 while (!workq.empty()) { 2117 CFGBlock *item = workq.front(); 2118 workq.pop(); 2119 for (CFGBlock::succ_iterator I=item->succ_begin(), 2120 E=item->succ_end(); 2121 I != E; 2122 ++I) { 2123 if ((*I) && !live[(*I)->getBlockID()]) { 2124 live.set((*I)->getBlockID()); 2125 ++count; 2126 workq.push(*I); 2127 } 2128 } 2129 } 2130 return count; 2131} 2132 2133static SourceLocation GetUnreachableLoc(CFGBlock &b, SourceRange &R1, 2134 SourceRange &R2) { 2135 Stmt *S; 2136 unsigned sn = 0; 2137 R1 = R2 = SourceRange(); 2138 2139 top: 2140 if (sn < b.size()) 2141 S = b[sn].getStmt(); 2142 else if (b.getTerminator()) 2143 S = b.getTerminator(); 2144 else 2145 return SourceLocation(); 2146 2147 switch (S->getStmtClass()) { 2148 case Expr::BinaryOperatorClass: { 2149 BinaryOperator *BO = cast<BinaryOperator>(S); 2150 if (BO->getOpcode() == BinaryOperator::Comma) { 2151 if (sn+1 < b.size()) 2152 return b[sn+1].getStmt()->getLocStart(); 2153 CFGBlock *n = &b; 2154 while (1) { 2155 if (n->getTerminator()) 2156 return n->getTerminator()->getLocStart(); 2157 if (n->succ_size() != 1) 2158 return SourceLocation(); 2159 n = n[0].succ_begin()[0]; 2160 if (n->pred_size() != 1) 2161 return SourceLocation(); 2162 if (!n->empty()) 2163 return n[0][0].getStmt()->getLocStart(); 2164 } 2165 } 2166 R1 = BO->getLHS()->getSourceRange(); 2167 R2 = BO->getRHS()->getSourceRange(); 2168 return BO->getOperatorLoc(); 2169 } 2170 case Expr::UnaryOperatorClass: { 2171 const UnaryOperator *UO = cast<UnaryOperator>(S); 2172 R1 = UO->getSubExpr()->getSourceRange(); 2173 return UO->getOperatorLoc(); 2174 } 2175 case Expr::CompoundAssignOperatorClass: { 2176 const CompoundAssignOperator *CAO = cast<CompoundAssignOperator>(S); 2177 R1 = CAO->getLHS()->getSourceRange(); 2178 R2 = CAO->getRHS()->getSourceRange(); 2179 return CAO->getOperatorLoc(); 2180 } 2181 case Expr::ConditionalOperatorClass: { 2182 const ConditionalOperator *CO = cast<ConditionalOperator>(S); 2183 return CO->getQuestionLoc(); 2184 } 2185 case Expr::MemberExprClass: { 2186 const MemberExpr *ME = cast<MemberExpr>(S); 2187 R1 = ME->getSourceRange(); 2188 return ME->getMemberLoc(); 2189 } 2190 case Expr::ArraySubscriptExprClass: { 2191 const ArraySubscriptExpr *ASE = cast<ArraySubscriptExpr>(S); 2192 R1 = ASE->getLHS()->getSourceRange(); 2193 R2 = ASE->getRHS()->getSourceRange(); 2194 return ASE->getRBracketLoc(); 2195 } 2196 case Expr::CStyleCastExprClass: { 2197 const CStyleCastExpr *CSC = cast<CStyleCastExpr>(S); 2198 R1 = CSC->getSubExpr()->getSourceRange(); 2199 return CSC->getLParenLoc(); 2200 } 2201 case Expr::CXXFunctionalCastExprClass: { 2202 const CXXFunctionalCastExpr *CE = cast <CXXFunctionalCastExpr>(S); 2203 R1 = CE->getSubExpr()->getSourceRange(); 2204 return CE->getTypeBeginLoc(); 2205 } 2206 case Expr::ImplicitCastExprClass: 2207 ++sn; 2208 goto top; 2209 case Stmt::CXXTryStmtClass: { 2210 return cast<CXXTryStmt>(S)->getHandler(0)->getCatchLoc(); 2211 } 2212 default: ; 2213 } 2214 R1 = S->getSourceRange(); 2215 return S->getLocStart(); 2216} 2217 2218static SourceLocation MarkLiveTop(CFGBlock *e, llvm::BitVector &live, 2219 SourceManager &SM) { 2220 std::queue<CFGBlock*> workq; 2221 // Prep work queue 2222 workq.push(e); 2223 SourceRange R1, R2; 2224 SourceLocation top = GetUnreachableLoc(*e, R1, R2); 2225 bool FromMainFile = false; 2226 bool FromSystemHeader = false; 2227 bool TopValid = false; 2228 if (top.isValid()) { 2229 FromMainFile = SM.isFromMainFile(top); 2230 FromSystemHeader = SM.isInSystemHeader(top); 2231 TopValid = true; 2232 } 2233 // Solve 2234 while (!workq.empty()) { 2235 CFGBlock *item = workq.front(); 2236 workq.pop(); 2237 SourceLocation c = GetUnreachableLoc(*item, R1, R2); 2238 if (c.isValid() 2239 && (!TopValid 2240 || (SM.isFromMainFile(c) && !FromMainFile) 2241 || (FromSystemHeader && !SM.isInSystemHeader(c)) 2242 || SM.isBeforeInTranslationUnit(c, top))) { 2243 top = c; 2244 FromMainFile = SM.isFromMainFile(top); 2245 FromSystemHeader = SM.isInSystemHeader(top); 2246 } 2247 live.set(item->getBlockID()); 2248 for (CFGBlock::succ_iterator I=item->succ_begin(), 2249 E=item->succ_end(); 2250 I != E; 2251 ++I) { 2252 if ((*I) && !live[(*I)->getBlockID()]) { 2253 live.set((*I)->getBlockID()); 2254 workq.push(*I); 2255 } 2256 } 2257 } 2258 return top; 2259} 2260 2261static int LineCmp(const void *p1, const void *p2) { 2262 SourceLocation *Line1 = (SourceLocation *)p1; 2263 SourceLocation *Line2 = (SourceLocation *)p2; 2264 return !(*Line1 < *Line2); 2265} 2266 2267namespace { 2268 struct ErrLoc { 2269 SourceLocation Loc; 2270 SourceRange R1; 2271 SourceRange R2; 2272 ErrLoc(SourceLocation l, SourceRange r1, SourceRange r2) 2273 : Loc(l), R1(r1), R2(r2) { } 2274 }; 2275} 2276 2277/// CheckUnreachable - Check for unreachable code. 2278void Sema::CheckUnreachable(AnalysisContext &AC) { 2279 unsigned count; 2280 // We avoid checking when there are errors, as the CFG won't faithfully match 2281 // the user's code. 2282 if (getDiagnostics().hasErrorOccurred()) 2283 return; 2284 if (Diags.getDiagnosticLevel(diag::warn_unreachable) == Diagnostic::Ignored) 2285 return; 2286 2287 CFG *cfg = AC.getCFG(); 2288 if (cfg == 0) 2289 return; 2290 2291 llvm::BitVector live(cfg->getNumBlockIDs()); 2292 // Mark all live things first. 2293 count = MarkLive(&cfg->getEntry(), live); 2294 2295 if (count == cfg->getNumBlockIDs()) 2296 // If there are no dead blocks, we're done. 2297 return; 2298 2299 SourceRange R1, R2; 2300 2301 llvm::SmallVector<ErrLoc, 24> lines; 2302 bool AddEHEdges = AC.getAddEHEdges(); 2303 // First, give warnings for blocks with no predecessors, as they 2304 // can't be part of a loop. 2305 for (CFG::iterator I = cfg->begin(), E = cfg->end(); I != E; ++I) { 2306 CFGBlock &b = **I; 2307 if (!live[b.getBlockID()]) { 2308 if (b.pred_begin() == b.pred_end()) { 2309 if (!AddEHEdges && b.getTerminator() 2310 && isa<CXXTryStmt>(b.getTerminator())) { 2311 // When not adding EH edges from calls, catch clauses 2312 // can otherwise seem dead. Avoid noting them as dead. 2313 count += MarkLive(&b, live); 2314 continue; 2315 } 2316 SourceLocation c = GetUnreachableLoc(b, R1, R2); 2317 if (!c.isValid()) { 2318 // Blocks without a location can't produce a warning, so don't mark 2319 // reachable blocks from here as live. 2320 live.set(b.getBlockID()); 2321 ++count; 2322 continue; 2323 } 2324 lines.push_back(ErrLoc(c, R1, R2)); 2325 // Avoid excessive errors by marking everything reachable from here 2326 count += MarkLive(&b, live); 2327 } 2328 } 2329 } 2330 2331 if (count < cfg->getNumBlockIDs()) { 2332 // And then give warnings for the tops of loops. 2333 for (CFG::iterator I = cfg->begin(), E = cfg->end(); I != E; ++I) { 2334 CFGBlock &b = **I; 2335 if (!live[b.getBlockID()]) 2336 // Avoid excessive errors by marking everything reachable from here 2337 lines.push_back(ErrLoc(MarkLiveTop(&b, live, 2338 Context.getSourceManager()), 2339 SourceRange(), SourceRange())); 2340 } 2341 } 2342 2343 llvm::array_pod_sort(lines.begin(), lines.end(), LineCmp); 2344 for (llvm::SmallVector<ErrLoc, 24>::iterator I = lines.begin(), 2345 E = lines.end(); 2346 I != E; 2347 ++I) 2348 if (I->Loc.isValid()) 2349 Diag(I->Loc, diag::warn_unreachable) << I->R1 << I->R2; 2350} 2351 2352/// CheckFallThrough - Check that we don't fall off the end of a 2353/// Statement that should return a value. 2354/// 2355/// \returns AlwaysFallThrough iff we always fall off the end of the statement, 2356/// MaybeFallThrough iff we might or might not fall off the end, 2357/// NeverFallThroughOrReturn iff we never fall off the end of the statement or 2358/// return. We assume NeverFallThrough iff we never fall off the end of the 2359/// statement but we may return. We assume that functions not marked noreturn 2360/// will return. 2361Sema::ControlFlowKind Sema::CheckFallThrough(AnalysisContext &AC) { 2362 CFG *cfg = AC.getCFG(); 2363 if (cfg == 0) 2364 // FIXME: This should be NeverFallThrough 2365 return NeverFallThroughOrReturn; 2366 2367 // The CFG leaves in dead things, and we don't want the dead code paths to 2368 // confuse us, so we mark all live things first. 2369 std::queue<CFGBlock*> workq; 2370 llvm::BitVector live(cfg->getNumBlockIDs()); 2371 unsigned count = MarkLive(&cfg->getEntry(), live); 2372 2373 bool AddEHEdges = AC.getAddEHEdges(); 2374 if (!AddEHEdges && count != cfg->getNumBlockIDs()) 2375 // When there are things remaining dead, and we didn't add EH edges 2376 // from CallExprs to the catch clauses, we have to go back and 2377 // mark them as live. 2378 for (CFG::iterator I = cfg->begin(), E = cfg->end(); I != E; ++I) { 2379 CFGBlock &b = **I; 2380 if (!live[b.getBlockID()]) { 2381 if (b.pred_begin() == b.pred_end()) { 2382 if (b.getTerminator() && isa<CXXTryStmt>(b.getTerminator())) 2383 // When not adding EH edges from calls, catch clauses 2384 // can otherwise seem dead. Avoid noting them as dead. 2385 count += MarkLive(&b, live); 2386 continue; 2387 } 2388 } 2389 } 2390 2391 // Now we know what is live, we check the live precessors of the exit block 2392 // and look for fall through paths, being careful to ignore normal returns, 2393 // and exceptional paths. 2394 bool HasLiveReturn = false; 2395 bool HasFakeEdge = false; 2396 bool HasPlainEdge = false; 2397 bool HasAbnormalEdge = false; 2398 for (CFGBlock::pred_iterator I=cfg->getExit().pred_begin(), 2399 E = cfg->getExit().pred_end(); 2400 I != E; 2401 ++I) { 2402 CFGBlock& B = **I; 2403 if (!live[B.getBlockID()]) 2404 continue; 2405 if (B.size() == 0) { 2406 if (B.getTerminator() && isa<CXXTryStmt>(B.getTerminator())) { 2407 HasAbnormalEdge = true; 2408 continue; 2409 } 2410 2411 // A labeled empty statement, or the entry block... 2412 HasPlainEdge = true; 2413 continue; 2414 } 2415 Stmt *S = B[B.size()-1]; 2416 if (isa<ReturnStmt>(S)) { 2417 HasLiveReturn = true; 2418 continue; 2419 } 2420 if (isa<ObjCAtThrowStmt>(S)) { 2421 HasFakeEdge = true; 2422 continue; 2423 } 2424 if (isa<CXXThrowExpr>(S)) { 2425 HasFakeEdge = true; 2426 continue; 2427 } 2428 if (const AsmStmt *AS = dyn_cast<AsmStmt>(S)) { 2429 if (AS->isMSAsm()) { 2430 HasFakeEdge = true; 2431 HasLiveReturn = true; 2432 continue; 2433 } 2434 } 2435 if (isa<CXXTryStmt>(S)) { 2436 HasAbnormalEdge = true; 2437 continue; 2438 } 2439 2440 bool NoReturnEdge = false; 2441 if (CallExpr *C = dyn_cast<CallExpr>(S)) { 2442 if (B.succ_begin()[0] != &cfg->getExit()) { 2443 HasAbnormalEdge = true; 2444 continue; 2445 } 2446 Expr *CEE = C->getCallee()->IgnoreParenCasts(); 2447 if (CEE->getType().getNoReturnAttr()) { 2448 NoReturnEdge = true; 2449 HasFakeEdge = true; 2450 } else if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(CEE)) { 2451 ValueDecl *VD = DRE->getDecl(); 2452 if (VD->hasAttr<NoReturnAttr>()) { 2453 NoReturnEdge = true; 2454 HasFakeEdge = true; 2455 } 2456 } 2457 } 2458 // FIXME: Add noreturn message sends. 2459 if (NoReturnEdge == false) 2460 HasPlainEdge = true; 2461 } 2462 if (!HasPlainEdge) { 2463 if (HasLiveReturn) 2464 return NeverFallThrough; 2465 return NeverFallThroughOrReturn; 2466 } 2467 if (HasAbnormalEdge || HasFakeEdge || HasLiveReturn) 2468 return MaybeFallThrough; 2469 // This says AlwaysFallThrough for calls to functions that are not marked 2470 // noreturn, that don't return. If people would like this warning to be more 2471 // accurate, such functions should be marked as noreturn. 2472 return AlwaysFallThrough; 2473} 2474 2475/// CheckFallThroughForFunctionDef - Check that we don't fall off the end of a 2476/// function that should return a value. Check that we don't fall off the end 2477/// of a noreturn function. We assume that functions and blocks not marked 2478/// noreturn will return. 2479void Sema::CheckFallThroughForFunctionDef(Decl *D, Stmt *Body, 2480 AnalysisContext &AC) { 2481 // FIXME: Would be nice if we had a better way to control cascading errors, 2482 // but for now, avoid them. The problem is that when Parse sees: 2483 // int foo() { return a; } 2484 // The return is eaten and the Sema code sees just: 2485 // int foo() { } 2486 // which this code would then warn about. 2487 if (getDiagnostics().hasErrorOccurred()) 2488 return; 2489 2490 bool ReturnsVoid = false; 2491 bool HasNoReturn = false; 2492 if (FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) { 2493 // For function templates, class templates and member function templates 2494 // we'll do the analysis at instantiation time. 2495 if (FD->isDependentContext()) 2496 return; 2497 2498 if (FD->getResultType()->isVoidType()) 2499 ReturnsVoid = true; 2500 if (FD->hasAttr<NoReturnAttr>() || 2501 FD->getType()->getAs<FunctionType>()->getNoReturnAttr()) 2502 HasNoReturn = true; 2503 } else if (ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(D)) { 2504 if (MD->getResultType()->isVoidType()) 2505 ReturnsVoid = true; 2506 if (MD->hasAttr<NoReturnAttr>()) 2507 HasNoReturn = true; 2508 } 2509 2510 // Short circuit for compilation speed. 2511 if ((Diags.getDiagnosticLevel(diag::warn_maybe_falloff_nonvoid_function) 2512 == Diagnostic::Ignored || ReturnsVoid) 2513 && (Diags.getDiagnosticLevel(diag::warn_noreturn_function_has_return_expr) 2514 == Diagnostic::Ignored || !HasNoReturn) 2515 && (Diags.getDiagnosticLevel(diag::warn_suggest_noreturn_block) 2516 == Diagnostic::Ignored || !ReturnsVoid)) 2517 return; 2518 // FIXME: Function try block 2519 if (CompoundStmt *Compound = dyn_cast<CompoundStmt>(Body)) { 2520 switch (CheckFallThrough(AC)) { 2521 case MaybeFallThrough: 2522 if (HasNoReturn) 2523 Diag(Compound->getRBracLoc(), diag::warn_falloff_noreturn_function); 2524 else if (!ReturnsVoid) 2525 Diag(Compound->getRBracLoc(),diag::warn_maybe_falloff_nonvoid_function); 2526 break; 2527 case AlwaysFallThrough: 2528 if (HasNoReturn) 2529 Diag(Compound->getRBracLoc(), diag::warn_falloff_noreturn_function); 2530 else if (!ReturnsVoid) 2531 Diag(Compound->getRBracLoc(), diag::warn_falloff_nonvoid_function); 2532 break; 2533 case NeverFallThroughOrReturn: 2534 if (ReturnsVoid && !HasNoReturn) 2535 Diag(Compound->getLBracLoc(), diag::warn_suggest_noreturn_function); 2536 break; 2537 case NeverFallThrough: 2538 break; 2539 } 2540 } 2541} 2542 2543/// CheckFallThroughForBlock - Check that we don't fall off the end of a block 2544/// that should return a value. Check that we don't fall off the end of a 2545/// noreturn block. We assume that functions and blocks not marked noreturn 2546/// will return. 2547void Sema::CheckFallThroughForBlock(QualType BlockTy, Stmt *Body, 2548 AnalysisContext &AC) { 2549 // FIXME: Would be nice if we had a better way to control cascading errors, 2550 // but for now, avoid them. The problem is that when Parse sees: 2551 // int foo() { return a; } 2552 // The return is eaten and the Sema code sees just: 2553 // int foo() { } 2554 // which this code would then warn about. 2555 if (getDiagnostics().hasErrorOccurred()) 2556 return; 2557 bool ReturnsVoid = false; 2558 bool HasNoReturn = false; 2559 if (const FunctionType *FT =BlockTy->getPointeeType()->getAs<FunctionType>()){ 2560 if (FT->getResultType()->isVoidType()) 2561 ReturnsVoid = true; 2562 if (FT->getNoReturnAttr()) 2563 HasNoReturn = true; 2564 } 2565 2566 // Short circuit for compilation speed. 2567 if (ReturnsVoid 2568 && !HasNoReturn 2569 && (Diags.getDiagnosticLevel(diag::warn_suggest_noreturn_block) 2570 == Diagnostic::Ignored || !ReturnsVoid)) 2571 return; 2572 // FIXME: Funtion try block 2573 if (CompoundStmt *Compound = dyn_cast<CompoundStmt>(Body)) { 2574 switch (CheckFallThrough(AC)) { 2575 case MaybeFallThrough: 2576 if (HasNoReturn) 2577 Diag(Compound->getRBracLoc(), diag::err_noreturn_block_has_return_expr); 2578 else if (!ReturnsVoid) 2579 Diag(Compound->getRBracLoc(), diag::err_maybe_falloff_nonvoid_block); 2580 break; 2581 case AlwaysFallThrough: 2582 if (HasNoReturn) 2583 Diag(Compound->getRBracLoc(), diag::err_noreturn_block_has_return_expr); 2584 else if (!ReturnsVoid) 2585 Diag(Compound->getRBracLoc(), diag::err_falloff_nonvoid_block); 2586 break; 2587 case NeverFallThroughOrReturn: 2588 if (ReturnsVoid) 2589 Diag(Compound->getLBracLoc(), diag::warn_suggest_noreturn_block); 2590 break; 2591 case NeverFallThrough: 2592 break; 2593 } 2594 } 2595} 2596 2597/// CheckParmsForFunctionDef - Check that the parameters of the given 2598/// function are appropriate for the definition of a function. This 2599/// takes care of any checks that cannot be performed on the 2600/// declaration itself, e.g., that the types of each of the function 2601/// parameters are complete. 2602bool Sema::CheckParmsForFunctionDef(FunctionDecl *FD) { 2603 bool HasInvalidParm = false; 2604 for (unsigned p = 0, NumParams = FD->getNumParams(); p < NumParams; ++p) { 2605 ParmVarDecl *Param = FD->getParamDecl(p); 2606 2607 // C99 6.7.5.3p4: the parameters in a parameter type list in a 2608 // function declarator that is part of a function definition of 2609 // that function shall not have incomplete type. 2610 // 2611 // This is also C++ [dcl.fct]p6. 2612 if (!Param->isInvalidDecl() && 2613 RequireCompleteType(Param->getLocation(), Param->getType(), 2614 diag::err_typecheck_decl_incomplete_type)) { 2615 Param->setInvalidDecl(); 2616 HasInvalidParm = true; 2617 } 2618 2619 // C99 6.9.1p5: If the declarator includes a parameter type list, the 2620 // declaration of each parameter shall include an identifier. 2621 if (Param->getIdentifier() == 0 && 2622 !Param->isImplicit() && 2623 !getLangOptions().CPlusPlus) 2624 Diag(Param->getLocation(), diag::err_parameter_name_omitted); 2625 2626 // C99 6.7.5.3p12: 2627 // If the function declarator is not part of a definition of that 2628 // function, parameters may have incomplete type and may use the [*] 2629 // notation in their sequences of declarator specifiers to specify 2630 // variable length array types. 2631 QualType PType = Param->getOriginalType(); 2632 if (const ArrayType *AT = Context.getAsArrayType(PType)) { 2633 if (AT->getSizeModifier() == ArrayType::Star) { 2634 // FIXME: This diagnosic should point the the '[*]' if source-location 2635 // information is added for it. 2636 Diag(Param->getLocation(), diag::err_array_star_in_function_definition); 2637 } 2638 } 2639 2640 if (getLangOptions().CPlusPlus) 2641 if (const RecordType *RT = Param->getType()->getAs<RecordType>()) 2642 FinalizeVarWithDestructor(Param, RT); 2643 } 2644 2645 return HasInvalidParm; 2646} 2647