SemaChecking.cpp revision e771a7ac11fb27f0e734e5de4d858f2c268895e5
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 bool MatchType(QualType A, QualType B, bool ignoreSign); 1093 1094 const Expr *getDataArg(unsigned i) const; 1095}; 1096} 1097 1098SourceRange CheckPrintfHandler::getFormatStringRange() { 1099 return OrigFormatExpr->getSourceRange(); 1100} 1101 1102SourceRange CheckPrintfHandler:: 1103getFormatSpecifierRange(const char *startSpecifier, unsigned specifierLen) { 1104 return SourceRange(getLocationOfByte(startSpecifier), 1105 getLocationOfByte(startSpecifier+specifierLen-1)); 1106} 1107 1108SourceLocation CheckPrintfHandler::getLocationOfByte(const char *x) { 1109 return S.getLocationOfStringLiteralByte(FExpr, x - Beg); 1110} 1111 1112void CheckPrintfHandler:: 1113HandleIncompleteFormatSpecifier(const char *startSpecifier, 1114 unsigned specifierLen) { 1115 SourceLocation Loc = getLocationOfByte(startSpecifier); 1116 S.Diag(Loc, diag::warn_printf_incomplete_specifier) 1117 << getFormatSpecifierRange(startSpecifier, specifierLen); 1118} 1119 1120void CheckPrintfHandler:: 1121HandleInvalidConversionSpecifier(const analyze_printf::FormatSpecifier &FS, 1122 const char *startSpecifier, 1123 unsigned specifierLen) { 1124 1125 ++NumConversions; 1126 const analyze_printf::ConversionSpecifier &CS = 1127 FS.getConversionSpecifier(); 1128 SourceLocation Loc = getLocationOfByte(CS.getStart()); 1129 S.Diag(Loc, diag::warn_printf_invalid_conversion) 1130 << llvm::StringRef(CS.getStart(), CS.getLength()) 1131 << getFormatSpecifierRange(startSpecifier, specifierLen); 1132} 1133 1134void CheckPrintfHandler::HandleNullChar(const char *nullCharacter) { 1135 // The presence of a null character is likely an error. 1136 S.Diag(getLocationOfByte(nullCharacter), 1137 diag::warn_printf_format_string_contains_null_char) 1138 << getFormatStringRange(); 1139} 1140 1141const Expr *CheckPrintfHandler::getDataArg(unsigned i) const { 1142 return TheCall->getArg(FormatIdx + i); 1143} 1144 1145bool CheckPrintfHandler::MatchType(QualType A, QualType B, bool ignoreSign) { 1146 A = S.Context.getCanonicalType(A).getUnqualifiedType(); 1147 B = S.Context.getCanonicalType(B).getUnqualifiedType(); 1148 1149 if (A == B) 1150 return true; 1151 1152 if (ignoreSign) { 1153 if (const BuiltinType *BT = B->getAs<BuiltinType>()) { 1154 switch (BT->getKind()) { 1155 default: 1156 return false; 1157 case BuiltinType::Char_S: 1158 case BuiltinType::SChar: 1159 return A == S.Context.UnsignedCharTy; 1160 case BuiltinType::Char_U: 1161 case BuiltinType::UChar: 1162 return A == S.Context.SignedCharTy; 1163 case BuiltinType::Short: 1164 return A == S.Context.UnsignedShortTy; 1165 case BuiltinType::UShort: 1166 return A == S.Context.ShortTy; 1167 case BuiltinType::Int: 1168 return A == S.Context.UnsignedIntTy; 1169 case BuiltinType::UInt: 1170 return A == S.Context.IntTy; 1171 case BuiltinType::Long: 1172 return A == S.Context.UnsignedLongTy; 1173 case BuiltinType::ULong: 1174 return A == S.Context.LongTy; 1175 case BuiltinType::LongLong: 1176 return A == S.Context.UnsignedLongLongTy; 1177 case BuiltinType::ULongLong: 1178 return A == S.Context.LongLongTy; 1179 } 1180 return A == B; 1181 } 1182 } 1183 return false; 1184} 1185 1186void CheckPrintfHandler::HandleFlags(const analyze_printf::FormatSpecifier &FS, 1187 llvm::StringRef flag, 1188 llvm::StringRef cspec, 1189 const char *startSpecifier, 1190 unsigned specifierLen) { 1191 const analyze_printf::ConversionSpecifier &CS = FS.getConversionSpecifier(); 1192 S.Diag(getLocationOfByte(CS.getStart()), diag::warn_printf_nonsensical_flag) 1193 << flag << cspec << getFormatSpecifierRange(startSpecifier, specifierLen); 1194} 1195 1196bool 1197CheckPrintfHandler::HandleAmount(const analyze_printf::OptionalAmount &Amt, 1198 unsigned MissingArgDiag, 1199 unsigned BadTypeDiag, 1200 const char *startSpecifier, 1201 unsigned specifierLen) { 1202 1203 if (Amt.hasDataArgument()) { 1204 ++NumConversions; 1205 if (!HasVAListArg) { 1206 if (NumConversions > NumDataArgs) { 1207 S.Diag(getLocationOfByte(Amt.getStart()), MissingArgDiag) 1208 << getFormatSpecifierRange(startSpecifier, specifierLen); 1209 // Don't do any more checking. We will just emit 1210 // spurious errors. 1211 return false; 1212 } 1213 1214 // Type check the data argument. It should be an 'int'. 1215 // Although not in conformance with C99, we also allow the argument to be 1216 // an 'unsigned int' as that is a reasonably safe case. GCC also 1217 // doesn't emit a warning for that case. 1218 const Expr *Arg = getDataArg(NumConversions); 1219 QualType T = Arg->getType(); 1220 if (!MatchType(T, S.Context.IntTy, true)) { 1221 S.Diag(getLocationOfByte(Amt.getStart()), BadTypeDiag) 1222 << S.Context.IntTy << T 1223 << getFormatSpecifierRange(startSpecifier, specifierLen) 1224 << Arg->getSourceRange(); 1225 // Don't do any more checking. We will just emit 1226 // spurious errors. 1227 return false; 1228 } 1229 } 1230 } 1231 return true; 1232} 1233 1234bool 1235CheckPrintfHandler::HandleFormatSpecifier(const analyze_printf::FormatSpecifier 1236 &FS, 1237 const char *startSpecifier, 1238 unsigned specifierLen) { 1239 1240 using namespace analyze_printf; 1241 const ConversionSpecifier &CS = FS.getConversionSpecifier(); 1242 1243 // First check if the field width, precision, and conversion specifier 1244 // have matching data arguments. 1245 if (!HandleAmount(FS.getFieldWidth(), 1246 diag::warn_printf_asterisk_width_missing_arg, 1247 diag::warn_printf_asterisk_width_wrong_type, 1248 startSpecifier, specifierLen)) { 1249 return false; 1250 } 1251 1252 if (!HandleAmount(FS.getPrecision(), 1253 diag::warn_printf_asterisk_precision_missing_arg, 1254 diag::warn_printf_asterisk_precision_wrong_type, 1255 startSpecifier, specifierLen)) { 1256 return false; 1257 } 1258 1259 // Check for using an Objective-C specific conversion specifier 1260 // in a non-ObjC literal. 1261 if (!IsObjCLiteral && CS.isObjCArg()) { 1262 HandleInvalidConversionSpecifier(FS, startSpecifier, specifierLen); 1263 1264 // Continue checking the other format specifiers. 1265 return true; 1266 } 1267 1268 if (!CS.consumesDataArgument()) { 1269 // FIXME: Technically specifying a precision or field width here 1270 // makes no sense. Worth issuing a warning at some point. 1271 return true; 1272 } 1273 1274 ++NumConversions; 1275 1276 // Are we using '%n'? Issue a warning about this being 1277 // a possible security issue. 1278 if (CS.getKind() == ConversionSpecifier::OutIntPtrArg) { 1279 S.Diag(getLocationOfByte(CS.getStart()), diag::warn_printf_write_back) 1280 << getFormatSpecifierRange(startSpecifier, specifierLen); 1281 // Continue checking the other format specifiers. 1282 return true; 1283 } 1284 1285 if (CS.getKind() == ConversionSpecifier::VoidPtrArg) { 1286 if (FS.getPrecision().getHowSpecified() != OptionalAmount::NotSpecified) 1287 S.Diag(getLocationOfByte(CS.getStart()), 1288 diag::warn_printf_nonsensical_precision) 1289 << CS.getCharacters() 1290 << getFormatSpecifierRange(startSpecifier, specifierLen); 1291 } 1292 if (CS.getKind() == ConversionSpecifier::VoidPtrArg || 1293 CS.getKind() == ConversionSpecifier::CStrArg) { 1294 // FIXME: Instead of using "0", "+", etc., eventually get them from 1295 // the FormatSpecifier. 1296 if (FS.hasLeadingZeros()) 1297 HandleFlags(FS, "0", CS.getCharacters(), startSpecifier, specifierLen); 1298 if (FS.hasPlusPrefix()) 1299 HandleFlags(FS, "+", CS.getCharacters(), startSpecifier, specifierLen); 1300 if (FS.hasSpacePrefix()) 1301 HandleFlags(FS, " ", CS.getCharacters(), startSpecifier, specifierLen); 1302 } 1303 1304 // The remaining checks depend on the data arguments. 1305 if (HasVAListArg) 1306 return true; 1307 1308 if (NumConversions > NumDataArgs) { 1309 S.Diag(getLocationOfByte(CS.getStart()), 1310 diag::warn_printf_insufficient_data_args) 1311 << getFormatSpecifierRange(startSpecifier, specifierLen); 1312 // Don't do any more checking. 1313 return false; 1314 } 1315 1316 // Now type check the data expression that matches the 1317 // format specifier. 1318 const Expr *Ex = getDataArg(NumConversions); 1319 const analyze_printf::ArgTypeResult &ATR = FS.getArgType(S.Context); 1320 1321 if (const QualType *T = ATR.getSpecificType()) { 1322 if (!MatchType(*T, Ex->getType(), true)) { 1323 // Check if we didn't match because of an implicit cast from a 'char' 1324 // or 'short' to an 'int'. This is done because printf is a varargs 1325 // function. 1326 if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Ex)) 1327 if (ICE->getType() == S.Context.IntTy) 1328 if (MatchType(*T, ICE->getSubExpr()->getType(), true)) 1329 return true; 1330 1331 S.Diag(getLocationOfByte(CS.getStart()), 1332 diag::warn_printf_conversion_argument_type_mismatch) 1333 << *T << Ex->getType() 1334 << getFormatSpecifierRange(startSpecifier, specifierLen) 1335 << Ex->getSourceRange(); 1336 } 1337 return true; 1338 } 1339 1340 return true; 1341} 1342 1343void CheckPrintfHandler::DoneProcessing() { 1344 // Does the number of data arguments exceed the number of 1345 // format conversions in the format string? 1346 if (!HasVAListArg && NumConversions < NumDataArgs) 1347 S.Diag(getDataArg(NumConversions+1)->getLocStart(), 1348 diag::warn_printf_too_many_data_args) 1349 << getFormatStringRange(); 1350} 1351 1352void Sema::CheckPrintfString(const StringLiteral *FExpr, 1353 const Expr *OrigFormatExpr, 1354 const CallExpr *TheCall, bool HasVAListArg, 1355 unsigned format_idx, unsigned firstDataArg) { 1356 1357 // CHECK: is the format string a wide literal? 1358 if (FExpr->isWide()) { 1359 Diag(FExpr->getLocStart(), 1360 diag::warn_printf_format_string_is_wide_literal) 1361 << OrigFormatExpr->getSourceRange(); 1362 return; 1363 } 1364 1365 // Str - The format string. NOTE: this is NOT null-terminated! 1366 const char *Str = FExpr->getStrData(); 1367 1368 // CHECK: empty format string? 1369 unsigned StrLen = FExpr->getByteLength(); 1370 1371 if (StrLen == 0) { 1372 Diag(FExpr->getLocStart(), diag::warn_printf_empty_format_string) 1373 << OrigFormatExpr->getSourceRange(); 1374 return; 1375 } 1376 1377 CheckPrintfHandler H(*this, FExpr, OrigFormatExpr, 1378 TheCall->getNumArgs() - firstDataArg, 1379 isa<ObjCStringLiteral>(OrigFormatExpr), Str, 1380 HasVAListArg, TheCall, format_idx); 1381 1382 if (!analyze_printf::ParseFormatString(H, Str, Str + StrLen)) 1383 H.DoneProcessing(); 1384} 1385 1386//===--- CHECK: Return Address of Stack Variable --------------------------===// 1387 1388static DeclRefExpr* EvalVal(Expr *E); 1389static DeclRefExpr* EvalAddr(Expr* E); 1390 1391/// CheckReturnStackAddr - Check if a return statement returns the address 1392/// of a stack variable. 1393void 1394Sema::CheckReturnStackAddr(Expr *RetValExp, QualType lhsType, 1395 SourceLocation ReturnLoc) { 1396 1397 // Perform checking for returned stack addresses. 1398 if (lhsType->isPointerType() || lhsType->isBlockPointerType()) { 1399 if (DeclRefExpr *DR = EvalAddr(RetValExp)) 1400 Diag(DR->getLocStart(), diag::warn_ret_stack_addr) 1401 << DR->getDecl()->getDeclName() << RetValExp->getSourceRange(); 1402 1403 // Skip over implicit cast expressions when checking for block expressions. 1404 RetValExp = RetValExp->IgnoreParenCasts(); 1405 1406 if (BlockExpr *C = dyn_cast<BlockExpr>(RetValExp)) 1407 if (C->hasBlockDeclRefExprs()) 1408 Diag(C->getLocStart(), diag::err_ret_local_block) 1409 << C->getSourceRange(); 1410 1411 if (AddrLabelExpr *ALE = dyn_cast<AddrLabelExpr>(RetValExp)) 1412 Diag(ALE->getLocStart(), diag::warn_ret_addr_label) 1413 << ALE->getSourceRange(); 1414 1415 } else if (lhsType->isReferenceType()) { 1416 // Perform checking for stack values returned by reference. 1417 // Check for a reference to the stack 1418 if (DeclRefExpr *DR = EvalVal(RetValExp)) 1419 Diag(DR->getLocStart(), diag::warn_ret_stack_ref) 1420 << DR->getDecl()->getDeclName() << RetValExp->getSourceRange(); 1421 } 1422} 1423 1424/// EvalAddr - EvalAddr and EvalVal are mutually recursive functions that 1425/// check if the expression in a return statement evaluates to an address 1426/// to a location on the stack. The recursion is used to traverse the 1427/// AST of the return expression, with recursion backtracking when we 1428/// encounter a subexpression that (1) clearly does not lead to the address 1429/// of a stack variable or (2) is something we cannot determine leads to 1430/// the address of a stack variable based on such local checking. 1431/// 1432/// EvalAddr processes expressions that are pointers that are used as 1433/// references (and not L-values). EvalVal handles all other values. 1434/// At the base case of the recursion is a check for a DeclRefExpr* in 1435/// the refers to a stack variable. 1436/// 1437/// This implementation handles: 1438/// 1439/// * pointer-to-pointer casts 1440/// * implicit conversions from array references to pointers 1441/// * taking the address of fields 1442/// * arbitrary interplay between "&" and "*" operators 1443/// * pointer arithmetic from an address of a stack variable 1444/// * taking the address of an array element where the array is on the stack 1445static DeclRefExpr* EvalAddr(Expr *E) { 1446 // We should only be called for evaluating pointer expressions. 1447 assert((E->getType()->isAnyPointerType() || 1448 E->getType()->isBlockPointerType() || 1449 E->getType()->isObjCQualifiedIdType()) && 1450 "EvalAddr only works on pointers"); 1451 1452 // Our "symbolic interpreter" is just a dispatch off the currently 1453 // viewed AST node. We then recursively traverse the AST by calling 1454 // EvalAddr and EvalVal appropriately. 1455 switch (E->getStmtClass()) { 1456 case Stmt::ParenExprClass: 1457 // Ignore parentheses. 1458 return EvalAddr(cast<ParenExpr>(E)->getSubExpr()); 1459 1460 case Stmt::UnaryOperatorClass: { 1461 // The only unary operator that make sense to handle here 1462 // is AddrOf. All others don't make sense as pointers. 1463 UnaryOperator *U = cast<UnaryOperator>(E); 1464 1465 if (U->getOpcode() == UnaryOperator::AddrOf) 1466 return EvalVal(U->getSubExpr()); 1467 else 1468 return NULL; 1469 } 1470 1471 case Stmt::BinaryOperatorClass: { 1472 // Handle pointer arithmetic. All other binary operators are not valid 1473 // in this context. 1474 BinaryOperator *B = cast<BinaryOperator>(E); 1475 BinaryOperator::Opcode op = B->getOpcode(); 1476 1477 if (op != BinaryOperator::Add && op != BinaryOperator::Sub) 1478 return NULL; 1479 1480 Expr *Base = B->getLHS(); 1481 1482 // Determine which argument is the real pointer base. It could be 1483 // the RHS argument instead of the LHS. 1484 if (!Base->getType()->isPointerType()) Base = B->getRHS(); 1485 1486 assert (Base->getType()->isPointerType()); 1487 return EvalAddr(Base); 1488 } 1489 1490 // For conditional operators we need to see if either the LHS or RHS are 1491 // valid DeclRefExpr*s. If one of them is valid, we return it. 1492 case Stmt::ConditionalOperatorClass: { 1493 ConditionalOperator *C = cast<ConditionalOperator>(E); 1494 1495 // Handle the GNU extension for missing LHS. 1496 if (Expr *lhsExpr = C->getLHS()) 1497 if (DeclRefExpr* LHS = EvalAddr(lhsExpr)) 1498 return LHS; 1499 1500 return EvalAddr(C->getRHS()); 1501 } 1502 1503 // For casts, we need to handle conversions from arrays to 1504 // pointer values, and pointer-to-pointer conversions. 1505 case Stmt::ImplicitCastExprClass: 1506 case Stmt::CStyleCastExprClass: 1507 case Stmt::CXXFunctionalCastExprClass: { 1508 Expr* SubExpr = cast<CastExpr>(E)->getSubExpr(); 1509 QualType T = SubExpr->getType(); 1510 1511 if (SubExpr->getType()->isPointerType() || 1512 SubExpr->getType()->isBlockPointerType() || 1513 SubExpr->getType()->isObjCQualifiedIdType()) 1514 return EvalAddr(SubExpr); 1515 else if (T->isArrayType()) 1516 return EvalVal(SubExpr); 1517 else 1518 return 0; 1519 } 1520 1521 // C++ casts. For dynamic casts, static casts, and const casts, we 1522 // are always converting from a pointer-to-pointer, so we just blow 1523 // through the cast. In the case the dynamic cast doesn't fail (and 1524 // return NULL), we take the conservative route and report cases 1525 // where we return the address of a stack variable. For Reinterpre 1526 // FIXME: The comment about is wrong; we're not always converting 1527 // from pointer to pointer. I'm guessing that this code should also 1528 // handle references to objects. 1529 case Stmt::CXXStaticCastExprClass: 1530 case Stmt::CXXDynamicCastExprClass: 1531 case Stmt::CXXConstCastExprClass: 1532 case Stmt::CXXReinterpretCastExprClass: { 1533 Expr *S = cast<CXXNamedCastExpr>(E)->getSubExpr(); 1534 if (S->getType()->isPointerType() || S->getType()->isBlockPointerType()) 1535 return EvalAddr(S); 1536 else 1537 return NULL; 1538 } 1539 1540 // Everything else: we simply don't reason about them. 1541 default: 1542 return NULL; 1543 } 1544} 1545 1546 1547/// EvalVal - This function is complements EvalAddr in the mutual recursion. 1548/// See the comments for EvalAddr for more details. 1549static DeclRefExpr* EvalVal(Expr *E) { 1550 1551 // We should only be called for evaluating non-pointer expressions, or 1552 // expressions with a pointer type that are not used as references but instead 1553 // are l-values (e.g., DeclRefExpr with a pointer type). 1554 1555 // Our "symbolic interpreter" is just a dispatch off the currently 1556 // viewed AST node. We then recursively traverse the AST by calling 1557 // EvalAddr and EvalVal appropriately. 1558 switch (E->getStmtClass()) { 1559 case Stmt::DeclRefExprClass: { 1560 // DeclRefExpr: the base case. When we hit a DeclRefExpr we are looking 1561 // at code that refers to a variable's name. We check if it has local 1562 // storage within the function, and if so, return the expression. 1563 DeclRefExpr *DR = cast<DeclRefExpr>(E); 1564 1565 if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl())) 1566 if (V->hasLocalStorage() && !V->getType()->isReferenceType()) return DR; 1567 1568 return NULL; 1569 } 1570 1571 case Stmt::ParenExprClass: 1572 // Ignore parentheses. 1573 return EvalVal(cast<ParenExpr>(E)->getSubExpr()); 1574 1575 case Stmt::UnaryOperatorClass: { 1576 // The only unary operator that make sense to handle here 1577 // is Deref. All others don't resolve to a "name." This includes 1578 // handling all sorts of rvalues passed to a unary operator. 1579 UnaryOperator *U = cast<UnaryOperator>(E); 1580 1581 if (U->getOpcode() == UnaryOperator::Deref) 1582 return EvalAddr(U->getSubExpr()); 1583 1584 return NULL; 1585 } 1586 1587 case Stmt::ArraySubscriptExprClass: { 1588 // Array subscripts are potential references to data on the stack. We 1589 // retrieve the DeclRefExpr* for the array variable if it indeed 1590 // has local storage. 1591 return EvalAddr(cast<ArraySubscriptExpr>(E)->getBase()); 1592 } 1593 1594 case Stmt::ConditionalOperatorClass: { 1595 // For conditional operators we need to see if either the LHS or RHS are 1596 // non-NULL DeclRefExpr's. If one is non-NULL, we return it. 1597 ConditionalOperator *C = cast<ConditionalOperator>(E); 1598 1599 // Handle the GNU extension for missing LHS. 1600 if (Expr *lhsExpr = C->getLHS()) 1601 if (DeclRefExpr *LHS = EvalVal(lhsExpr)) 1602 return LHS; 1603 1604 return EvalVal(C->getRHS()); 1605 } 1606 1607 // Accesses to members are potential references to data on the stack. 1608 case Stmt::MemberExprClass: { 1609 MemberExpr *M = cast<MemberExpr>(E); 1610 1611 // Check for indirect access. We only want direct field accesses. 1612 if (!M->isArrow()) 1613 return EvalVal(M->getBase()); 1614 else 1615 return NULL; 1616 } 1617 1618 // Everything else: we simply don't reason about them. 1619 default: 1620 return NULL; 1621 } 1622} 1623 1624//===--- CHECK: Floating-Point comparisons (-Wfloat-equal) ---------------===// 1625 1626/// Check for comparisons of floating point operands using != and ==. 1627/// Issue a warning if these are no self-comparisons, as they are not likely 1628/// to do what the programmer intended. 1629void Sema::CheckFloatComparison(SourceLocation loc, Expr* lex, Expr *rex) { 1630 bool EmitWarning = true; 1631 1632 Expr* LeftExprSansParen = lex->IgnoreParens(); 1633 Expr* RightExprSansParen = rex->IgnoreParens(); 1634 1635 // Special case: check for x == x (which is OK). 1636 // Do not emit warnings for such cases. 1637 if (DeclRefExpr* DRL = dyn_cast<DeclRefExpr>(LeftExprSansParen)) 1638 if (DeclRefExpr* DRR = dyn_cast<DeclRefExpr>(RightExprSansParen)) 1639 if (DRL->getDecl() == DRR->getDecl()) 1640 EmitWarning = false; 1641 1642 1643 // Special case: check for comparisons against literals that can be exactly 1644 // represented by APFloat. In such cases, do not emit a warning. This 1645 // is a heuristic: often comparison against such literals are used to 1646 // detect if a value in a variable has not changed. This clearly can 1647 // lead to false negatives. 1648 if (EmitWarning) { 1649 if (FloatingLiteral* FLL = dyn_cast<FloatingLiteral>(LeftExprSansParen)) { 1650 if (FLL->isExact()) 1651 EmitWarning = false; 1652 } else 1653 if (FloatingLiteral* FLR = dyn_cast<FloatingLiteral>(RightExprSansParen)){ 1654 if (FLR->isExact()) 1655 EmitWarning = false; 1656 } 1657 } 1658 1659 // Check for comparisons with builtin types. 1660 if (EmitWarning) 1661 if (CallExpr* CL = dyn_cast<CallExpr>(LeftExprSansParen)) 1662 if (CL->isBuiltinCall(Context)) 1663 EmitWarning = false; 1664 1665 if (EmitWarning) 1666 if (CallExpr* CR = dyn_cast<CallExpr>(RightExprSansParen)) 1667 if (CR->isBuiltinCall(Context)) 1668 EmitWarning = false; 1669 1670 // Emit the diagnostic. 1671 if (EmitWarning) 1672 Diag(loc, diag::warn_floatingpoint_eq) 1673 << lex->getSourceRange() << rex->getSourceRange(); 1674} 1675 1676//===--- CHECK: Integer mixed-sign comparisons (-Wsign-compare) --------===// 1677//===--- CHECK: Lossy implicit conversions (-Wconversion) --------------===// 1678 1679namespace { 1680 1681/// Structure recording the 'active' range of an integer-valued 1682/// expression. 1683struct IntRange { 1684 /// The number of bits active in the int. 1685 unsigned Width; 1686 1687 /// True if the int is known not to have negative values. 1688 bool NonNegative; 1689 1690 IntRange() {} 1691 IntRange(unsigned Width, bool NonNegative) 1692 : Width(Width), NonNegative(NonNegative) 1693 {} 1694 1695 // Returns the range of the bool type. 1696 static IntRange forBoolType() { 1697 return IntRange(1, true); 1698 } 1699 1700 // Returns the range of an integral type. 1701 static IntRange forType(ASTContext &C, QualType T) { 1702 return forCanonicalType(C, T->getCanonicalTypeInternal().getTypePtr()); 1703 } 1704 1705 // Returns the range of an integeral type based on its canonical 1706 // representation. 1707 static IntRange forCanonicalType(ASTContext &C, const Type *T) { 1708 assert(T->isCanonicalUnqualified()); 1709 1710 if (const VectorType *VT = dyn_cast<VectorType>(T)) 1711 T = VT->getElementType().getTypePtr(); 1712 if (const ComplexType *CT = dyn_cast<ComplexType>(T)) 1713 T = CT->getElementType().getTypePtr(); 1714 if (const EnumType *ET = dyn_cast<EnumType>(T)) 1715 T = ET->getDecl()->getIntegerType().getTypePtr(); 1716 1717 const BuiltinType *BT = cast<BuiltinType>(T); 1718 assert(BT->isInteger()); 1719 1720 return IntRange(C.getIntWidth(QualType(T, 0)), BT->isUnsignedInteger()); 1721 } 1722 1723 // Returns the supremum of two ranges: i.e. their conservative merge. 1724 static IntRange join(const IntRange &L, const IntRange &R) { 1725 return IntRange(std::max(L.Width, R.Width), 1726 L.NonNegative && R.NonNegative); 1727 } 1728 1729 // Returns the infinum of two ranges: i.e. their aggressive merge. 1730 static IntRange meet(const IntRange &L, const IntRange &R) { 1731 return IntRange(std::min(L.Width, R.Width), 1732 L.NonNegative || R.NonNegative); 1733 } 1734}; 1735 1736IntRange GetValueRange(ASTContext &C, llvm::APSInt &value, unsigned MaxWidth) { 1737 if (value.isSigned() && value.isNegative()) 1738 return IntRange(value.getMinSignedBits(), false); 1739 1740 if (value.getBitWidth() > MaxWidth) 1741 value.trunc(MaxWidth); 1742 1743 // isNonNegative() just checks the sign bit without considering 1744 // signedness. 1745 return IntRange(value.getActiveBits(), true); 1746} 1747 1748IntRange GetValueRange(ASTContext &C, APValue &result, QualType Ty, 1749 unsigned MaxWidth) { 1750 if (result.isInt()) 1751 return GetValueRange(C, result.getInt(), MaxWidth); 1752 1753 if (result.isVector()) { 1754 IntRange R = GetValueRange(C, result.getVectorElt(0), Ty, MaxWidth); 1755 for (unsigned i = 1, e = result.getVectorLength(); i != e; ++i) { 1756 IntRange El = GetValueRange(C, result.getVectorElt(i), Ty, MaxWidth); 1757 R = IntRange::join(R, El); 1758 } 1759 return R; 1760 } 1761 1762 if (result.isComplexInt()) { 1763 IntRange R = GetValueRange(C, result.getComplexIntReal(), MaxWidth); 1764 IntRange I = GetValueRange(C, result.getComplexIntImag(), MaxWidth); 1765 return IntRange::join(R, I); 1766 } 1767 1768 // This can happen with lossless casts to intptr_t of "based" lvalues. 1769 // Assume it might use arbitrary bits. 1770 // FIXME: The only reason we need to pass the type in here is to get 1771 // the sign right on this one case. It would be nice if APValue 1772 // preserved this. 1773 assert(result.isLValue()); 1774 return IntRange(MaxWidth, Ty->isUnsignedIntegerType()); 1775} 1776 1777/// Pseudo-evaluate the given integer expression, estimating the 1778/// range of values it might take. 1779/// 1780/// \param MaxWidth - the width to which the value will be truncated 1781IntRange GetExprRange(ASTContext &C, Expr *E, unsigned MaxWidth) { 1782 E = E->IgnoreParens(); 1783 1784 // Try a full evaluation first. 1785 Expr::EvalResult result; 1786 if (E->Evaluate(result, C)) 1787 return GetValueRange(C, result.Val, E->getType(), MaxWidth); 1788 1789 // I think we only want to look through implicit casts here; if the 1790 // user has an explicit widening cast, we should treat the value as 1791 // being of the new, wider type. 1792 if (ImplicitCastExpr *CE = dyn_cast<ImplicitCastExpr>(E)) { 1793 if (CE->getCastKind() == CastExpr::CK_NoOp) 1794 return GetExprRange(C, CE->getSubExpr(), MaxWidth); 1795 1796 IntRange OutputTypeRange = IntRange::forType(C, CE->getType()); 1797 1798 bool isIntegerCast = (CE->getCastKind() == CastExpr::CK_IntegralCast); 1799 if (!isIntegerCast && CE->getCastKind() == CastExpr::CK_Unknown) 1800 isIntegerCast = CE->getSubExpr()->getType()->isIntegerType(); 1801 1802 // Assume that non-integer casts can span the full range of the type. 1803 if (!isIntegerCast) 1804 return OutputTypeRange; 1805 1806 IntRange SubRange 1807 = GetExprRange(C, CE->getSubExpr(), 1808 std::min(MaxWidth, OutputTypeRange.Width)); 1809 1810 // Bail out if the subexpr's range is as wide as the cast type. 1811 if (SubRange.Width >= OutputTypeRange.Width) 1812 return OutputTypeRange; 1813 1814 // Otherwise, we take the smaller width, and we're non-negative if 1815 // either the output type or the subexpr is. 1816 return IntRange(SubRange.Width, 1817 SubRange.NonNegative || OutputTypeRange.NonNegative); 1818 } 1819 1820 if (ConditionalOperator *CO = dyn_cast<ConditionalOperator>(E)) { 1821 // If we can fold the condition, just take that operand. 1822 bool CondResult; 1823 if (CO->getCond()->EvaluateAsBooleanCondition(CondResult, C)) 1824 return GetExprRange(C, CondResult ? CO->getTrueExpr() 1825 : CO->getFalseExpr(), 1826 MaxWidth); 1827 1828 // Otherwise, conservatively merge. 1829 IntRange L = GetExprRange(C, CO->getTrueExpr(), MaxWidth); 1830 IntRange R = GetExprRange(C, CO->getFalseExpr(), MaxWidth); 1831 return IntRange::join(L, R); 1832 } 1833 1834 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) { 1835 switch (BO->getOpcode()) { 1836 1837 // Boolean-valued operations are single-bit and positive. 1838 case BinaryOperator::LAnd: 1839 case BinaryOperator::LOr: 1840 case BinaryOperator::LT: 1841 case BinaryOperator::GT: 1842 case BinaryOperator::LE: 1843 case BinaryOperator::GE: 1844 case BinaryOperator::EQ: 1845 case BinaryOperator::NE: 1846 return IntRange::forBoolType(); 1847 1848 // Operations with opaque sources are black-listed. 1849 case BinaryOperator::PtrMemD: 1850 case BinaryOperator::PtrMemI: 1851 return IntRange::forType(C, E->getType()); 1852 1853 // Bitwise-and uses the *infinum* of the two source ranges. 1854 case BinaryOperator::And: 1855 return IntRange::meet(GetExprRange(C, BO->getLHS(), MaxWidth), 1856 GetExprRange(C, BO->getRHS(), MaxWidth)); 1857 1858 // Left shift gets black-listed based on a judgement call. 1859 case BinaryOperator::Shl: 1860 return IntRange::forType(C, E->getType()); 1861 1862 // Right shift by a constant can narrow its left argument. 1863 case BinaryOperator::Shr: { 1864 IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth); 1865 1866 // If the shift amount is a positive constant, drop the width by 1867 // that much. 1868 llvm::APSInt shift; 1869 if (BO->getRHS()->isIntegerConstantExpr(shift, C) && 1870 shift.isNonNegative()) { 1871 unsigned zext = shift.getZExtValue(); 1872 if (zext >= L.Width) 1873 L.Width = (L.NonNegative ? 0 : 1); 1874 else 1875 L.Width -= zext; 1876 } 1877 1878 return L; 1879 } 1880 1881 // Comma acts as its right operand. 1882 case BinaryOperator::Comma: 1883 return GetExprRange(C, BO->getRHS(), MaxWidth); 1884 1885 // Black-list pointer subtractions. 1886 case BinaryOperator::Sub: 1887 if (BO->getLHS()->getType()->isPointerType()) 1888 return IntRange::forType(C, E->getType()); 1889 // fallthrough 1890 1891 default: 1892 break; 1893 } 1894 1895 // Treat every other operator as if it were closed on the 1896 // narrowest type that encompasses both operands. 1897 IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth); 1898 IntRange R = GetExprRange(C, BO->getRHS(), MaxWidth); 1899 return IntRange::join(L, R); 1900 } 1901 1902 if (UnaryOperator *UO = dyn_cast<UnaryOperator>(E)) { 1903 switch (UO->getOpcode()) { 1904 // Boolean-valued operations are white-listed. 1905 case UnaryOperator::LNot: 1906 return IntRange::forBoolType(); 1907 1908 // Operations with opaque sources are black-listed. 1909 case UnaryOperator::Deref: 1910 case UnaryOperator::AddrOf: // should be impossible 1911 case UnaryOperator::OffsetOf: 1912 return IntRange::forType(C, E->getType()); 1913 1914 default: 1915 return GetExprRange(C, UO->getSubExpr(), MaxWidth); 1916 } 1917 } 1918 1919 FieldDecl *BitField = E->getBitField(); 1920 if (BitField) { 1921 llvm::APSInt BitWidthAP = BitField->getBitWidth()->EvaluateAsInt(C); 1922 unsigned BitWidth = BitWidthAP.getZExtValue(); 1923 1924 return IntRange(BitWidth, BitField->getType()->isUnsignedIntegerType()); 1925 } 1926 1927 return IntRange::forType(C, E->getType()); 1928} 1929 1930/// Checks whether the given value, which currently has the given 1931/// source semantics, has the same value when coerced through the 1932/// target semantics. 1933bool IsSameFloatAfterCast(const llvm::APFloat &value, 1934 const llvm::fltSemantics &Src, 1935 const llvm::fltSemantics &Tgt) { 1936 llvm::APFloat truncated = value; 1937 1938 bool ignored; 1939 truncated.convert(Src, llvm::APFloat::rmNearestTiesToEven, &ignored); 1940 truncated.convert(Tgt, llvm::APFloat::rmNearestTiesToEven, &ignored); 1941 1942 return truncated.bitwiseIsEqual(value); 1943} 1944 1945/// Checks whether the given value, which currently has the given 1946/// source semantics, has the same value when coerced through the 1947/// target semantics. 1948/// 1949/// The value might be a vector of floats (or a complex number). 1950bool IsSameFloatAfterCast(const APValue &value, 1951 const llvm::fltSemantics &Src, 1952 const llvm::fltSemantics &Tgt) { 1953 if (value.isFloat()) 1954 return IsSameFloatAfterCast(value.getFloat(), Src, Tgt); 1955 1956 if (value.isVector()) { 1957 for (unsigned i = 0, e = value.getVectorLength(); i != e; ++i) 1958 if (!IsSameFloatAfterCast(value.getVectorElt(i), Src, Tgt)) 1959 return false; 1960 return true; 1961 } 1962 1963 assert(value.isComplexFloat()); 1964 return (IsSameFloatAfterCast(value.getComplexFloatReal(), Src, Tgt) && 1965 IsSameFloatAfterCast(value.getComplexFloatImag(), Src, Tgt)); 1966} 1967 1968} // end anonymous namespace 1969 1970/// \brief Implements -Wsign-compare. 1971/// 1972/// \param lex the left-hand expression 1973/// \param rex the right-hand expression 1974/// \param OpLoc the location of the joining operator 1975/// \param Equality whether this is an "equality-like" join, which 1976/// suppresses the warning in some cases 1977void Sema::CheckSignCompare(Expr *lex, Expr *rex, SourceLocation OpLoc, 1978 const PartialDiagnostic &PD, bool Equality) { 1979 // Don't warn if we're in an unevaluated context. 1980 if (ExprEvalContexts.back().Context == Unevaluated) 1981 return; 1982 1983 // If either expression is value-dependent, don't warn. We'll get another 1984 // chance at instantiation time. 1985 if (lex->isValueDependent() || rex->isValueDependent()) 1986 return; 1987 1988 QualType lt = lex->getType(), rt = rex->getType(); 1989 1990 // Only warn if both operands are integral. 1991 if (!lt->isIntegerType() || !rt->isIntegerType()) 1992 return; 1993 1994 // In C, the width of a bitfield determines its type, and the 1995 // declared type only contributes the signedness. This duplicates 1996 // the work that will later be done by UsualUnaryConversions. 1997 // Eventually, this check will be reorganized in a way that avoids 1998 // this duplication. 1999 if (!getLangOptions().CPlusPlus) { 2000 QualType tmp; 2001 tmp = Context.isPromotableBitField(lex); 2002 if (!tmp.isNull()) lt = tmp; 2003 tmp = Context.isPromotableBitField(rex); 2004 if (!tmp.isNull()) rt = tmp; 2005 } 2006 2007 // The rule is that the signed operand becomes unsigned, so isolate the 2008 // signed operand. 2009 Expr *signedOperand = lex, *unsignedOperand = rex; 2010 QualType signedType = lt, unsignedType = rt; 2011 if (lt->isSignedIntegerType()) { 2012 if (rt->isSignedIntegerType()) return; 2013 } else { 2014 if (!rt->isSignedIntegerType()) return; 2015 std::swap(signedOperand, unsignedOperand); 2016 std::swap(signedType, unsignedType); 2017 } 2018 2019 unsigned unsignedWidth = Context.getIntWidth(unsignedType); 2020 unsigned signedWidth = Context.getIntWidth(signedType); 2021 2022 // If the unsigned type is strictly smaller than the signed type, 2023 // then (1) the result type will be signed and (2) the unsigned 2024 // value will fit fully within the signed type, and thus the result 2025 // of the comparison will be exact. 2026 if (signedWidth > unsignedWidth) 2027 return; 2028 2029 // Otherwise, calculate the effective ranges. 2030 IntRange signedRange = GetExprRange(Context, signedOperand, signedWidth); 2031 IntRange unsignedRange = GetExprRange(Context, unsignedOperand, unsignedWidth); 2032 2033 // We should never be unable to prove that the unsigned operand is 2034 // non-negative. 2035 assert(unsignedRange.NonNegative && "unsigned range includes negative?"); 2036 2037 // If the signed operand is non-negative, then the signed->unsigned 2038 // conversion won't change it. 2039 if (signedRange.NonNegative) 2040 return; 2041 2042 // For (in)equality comparisons, if the unsigned operand is a 2043 // constant which cannot collide with a overflowed signed operand, 2044 // then reinterpreting the signed operand as unsigned will not 2045 // change the result of the comparison. 2046 if (Equality && unsignedRange.Width < unsignedWidth) 2047 return; 2048 2049 Diag(OpLoc, PD) 2050 << lt << rt << lex->getSourceRange() << rex->getSourceRange(); 2051} 2052 2053/// Diagnose an implicit cast; purely a helper for CheckImplicitConversion. 2054static void DiagnoseImpCast(Sema &S, Expr *E, QualType T, unsigned diag) { 2055 S.Diag(E->getExprLoc(), diag) << E->getType() << T << E->getSourceRange(); 2056} 2057 2058/// Implements -Wconversion. 2059void Sema::CheckImplicitConversion(Expr *E, QualType T) { 2060 // Don't diagnose in unevaluated contexts. 2061 if (ExprEvalContexts.back().Context == Sema::Unevaluated) 2062 return; 2063 2064 // Don't diagnose for value-dependent expressions. 2065 if (E->isValueDependent()) 2066 return; 2067 2068 const Type *Source = Context.getCanonicalType(E->getType()).getTypePtr(); 2069 const Type *Target = Context.getCanonicalType(T).getTypePtr(); 2070 2071 // Never diagnose implicit casts to bool. 2072 if (Target->isSpecificBuiltinType(BuiltinType::Bool)) 2073 return; 2074 2075 // Strip vector types. 2076 if (isa<VectorType>(Source)) { 2077 if (!isa<VectorType>(Target)) 2078 return DiagnoseImpCast(*this, E, T, diag::warn_impcast_vector_scalar); 2079 2080 Source = cast<VectorType>(Source)->getElementType().getTypePtr(); 2081 Target = cast<VectorType>(Target)->getElementType().getTypePtr(); 2082 } 2083 2084 // Strip complex types. 2085 if (isa<ComplexType>(Source)) { 2086 if (!isa<ComplexType>(Target)) 2087 return DiagnoseImpCast(*this, E, T, diag::warn_impcast_complex_scalar); 2088 2089 Source = cast<ComplexType>(Source)->getElementType().getTypePtr(); 2090 Target = cast<ComplexType>(Target)->getElementType().getTypePtr(); 2091 } 2092 2093 const BuiltinType *SourceBT = dyn_cast<BuiltinType>(Source); 2094 const BuiltinType *TargetBT = dyn_cast<BuiltinType>(Target); 2095 2096 // If the source is floating point... 2097 if (SourceBT && SourceBT->isFloatingPoint()) { 2098 // ...and the target is floating point... 2099 if (TargetBT && TargetBT->isFloatingPoint()) { 2100 // ...then warn if we're dropping FP rank. 2101 2102 // Builtin FP kinds are ordered by increasing FP rank. 2103 if (SourceBT->getKind() > TargetBT->getKind()) { 2104 // Don't warn about float constants that are precisely 2105 // representable in the target type. 2106 Expr::EvalResult result; 2107 if (E->Evaluate(result, Context)) { 2108 // Value might be a float, a float vector, or a float complex. 2109 if (IsSameFloatAfterCast(result.Val, 2110 Context.getFloatTypeSemantics(QualType(TargetBT, 0)), 2111 Context.getFloatTypeSemantics(QualType(SourceBT, 0)))) 2112 return; 2113 } 2114 2115 DiagnoseImpCast(*this, E, T, diag::warn_impcast_float_precision); 2116 } 2117 return; 2118 } 2119 2120 // If the target is integral, always warn. 2121 if ((TargetBT && TargetBT->isInteger())) 2122 // TODO: don't warn for integer values? 2123 return DiagnoseImpCast(*this, E, T, diag::warn_impcast_float_integer); 2124 2125 return; 2126 } 2127 2128 if (!Source->isIntegerType() || !Target->isIntegerType()) 2129 return; 2130 2131 IntRange SourceRange = GetExprRange(Context, E, Context.getIntWidth(E->getType())); 2132 IntRange TargetRange = IntRange::forCanonicalType(Context, Target); 2133 2134 // FIXME: also signed<->unsigned? 2135 2136 if (SourceRange.Width > TargetRange.Width) { 2137 // People want to build with -Wshorten-64-to-32 and not -Wconversion 2138 // and by god we'll let them. 2139 if (SourceRange.Width == 64 && TargetRange.Width == 32) 2140 return DiagnoseImpCast(*this, E, T, diag::warn_impcast_integer_64_32); 2141 return DiagnoseImpCast(*this, E, T, diag::warn_impcast_integer_precision); 2142 } 2143 2144 return; 2145} 2146 2147// MarkLive - Mark all the blocks reachable from e as live. Returns the total 2148// number of blocks just marked live. 2149static unsigned MarkLive(CFGBlock *e, llvm::BitVector &live) { 2150 unsigned count = 0; 2151 std::queue<CFGBlock*> workq; 2152 // Prep work queue 2153 live.set(e->getBlockID()); 2154 ++count; 2155 workq.push(e); 2156 // Solve 2157 while (!workq.empty()) { 2158 CFGBlock *item = workq.front(); 2159 workq.pop(); 2160 for (CFGBlock::succ_iterator I=item->succ_begin(), 2161 E=item->succ_end(); 2162 I != E; 2163 ++I) { 2164 if ((*I) && !live[(*I)->getBlockID()]) { 2165 live.set((*I)->getBlockID()); 2166 ++count; 2167 workq.push(*I); 2168 } 2169 } 2170 } 2171 return count; 2172} 2173 2174static SourceLocation GetUnreachableLoc(CFGBlock &b, SourceRange &R1, 2175 SourceRange &R2) { 2176 Stmt *S; 2177 unsigned sn = 0; 2178 R1 = R2 = SourceRange(); 2179 2180 top: 2181 if (sn < b.size()) 2182 S = b[sn].getStmt(); 2183 else if (b.getTerminator()) 2184 S = b.getTerminator(); 2185 else 2186 return SourceLocation(); 2187 2188 switch (S->getStmtClass()) { 2189 case Expr::BinaryOperatorClass: { 2190 BinaryOperator *BO = cast<BinaryOperator>(S); 2191 if (BO->getOpcode() == BinaryOperator::Comma) { 2192 if (sn+1 < b.size()) 2193 return b[sn+1].getStmt()->getLocStart(); 2194 CFGBlock *n = &b; 2195 while (1) { 2196 if (n->getTerminator()) 2197 return n->getTerminator()->getLocStart(); 2198 if (n->succ_size() != 1) 2199 return SourceLocation(); 2200 n = n[0].succ_begin()[0]; 2201 if (n->pred_size() != 1) 2202 return SourceLocation(); 2203 if (!n->empty()) 2204 return n[0][0].getStmt()->getLocStart(); 2205 } 2206 } 2207 R1 = BO->getLHS()->getSourceRange(); 2208 R2 = BO->getRHS()->getSourceRange(); 2209 return BO->getOperatorLoc(); 2210 } 2211 case Expr::UnaryOperatorClass: { 2212 const UnaryOperator *UO = cast<UnaryOperator>(S); 2213 R1 = UO->getSubExpr()->getSourceRange(); 2214 return UO->getOperatorLoc(); 2215 } 2216 case Expr::CompoundAssignOperatorClass: { 2217 const CompoundAssignOperator *CAO = cast<CompoundAssignOperator>(S); 2218 R1 = CAO->getLHS()->getSourceRange(); 2219 R2 = CAO->getRHS()->getSourceRange(); 2220 return CAO->getOperatorLoc(); 2221 } 2222 case Expr::ConditionalOperatorClass: { 2223 const ConditionalOperator *CO = cast<ConditionalOperator>(S); 2224 return CO->getQuestionLoc(); 2225 } 2226 case Expr::MemberExprClass: { 2227 const MemberExpr *ME = cast<MemberExpr>(S); 2228 R1 = ME->getSourceRange(); 2229 return ME->getMemberLoc(); 2230 } 2231 case Expr::ArraySubscriptExprClass: { 2232 const ArraySubscriptExpr *ASE = cast<ArraySubscriptExpr>(S); 2233 R1 = ASE->getLHS()->getSourceRange(); 2234 R2 = ASE->getRHS()->getSourceRange(); 2235 return ASE->getRBracketLoc(); 2236 } 2237 case Expr::CStyleCastExprClass: { 2238 const CStyleCastExpr *CSC = cast<CStyleCastExpr>(S); 2239 R1 = CSC->getSubExpr()->getSourceRange(); 2240 return CSC->getLParenLoc(); 2241 } 2242 case Expr::CXXFunctionalCastExprClass: { 2243 const CXXFunctionalCastExpr *CE = cast <CXXFunctionalCastExpr>(S); 2244 R1 = CE->getSubExpr()->getSourceRange(); 2245 return CE->getTypeBeginLoc(); 2246 } 2247 case Expr::ImplicitCastExprClass: 2248 ++sn; 2249 goto top; 2250 case Stmt::CXXTryStmtClass: { 2251 return cast<CXXTryStmt>(S)->getHandler(0)->getCatchLoc(); 2252 } 2253 default: ; 2254 } 2255 R1 = S->getSourceRange(); 2256 return S->getLocStart(); 2257} 2258 2259static SourceLocation MarkLiveTop(CFGBlock *e, llvm::BitVector &live, 2260 SourceManager &SM) { 2261 std::queue<CFGBlock*> workq; 2262 // Prep work queue 2263 workq.push(e); 2264 SourceRange R1, R2; 2265 SourceLocation top = GetUnreachableLoc(*e, R1, R2); 2266 bool FromMainFile = false; 2267 bool FromSystemHeader = false; 2268 bool TopValid = false; 2269 if (top.isValid()) { 2270 FromMainFile = SM.isFromMainFile(top); 2271 FromSystemHeader = SM.isInSystemHeader(top); 2272 TopValid = true; 2273 } 2274 // Solve 2275 while (!workq.empty()) { 2276 CFGBlock *item = workq.front(); 2277 workq.pop(); 2278 SourceLocation c = GetUnreachableLoc(*item, R1, R2); 2279 if (c.isValid() 2280 && (!TopValid 2281 || (SM.isFromMainFile(c) && !FromMainFile) 2282 || (FromSystemHeader && !SM.isInSystemHeader(c)) 2283 || SM.isBeforeInTranslationUnit(c, top))) { 2284 top = c; 2285 FromMainFile = SM.isFromMainFile(top); 2286 FromSystemHeader = SM.isInSystemHeader(top); 2287 } 2288 live.set(item->getBlockID()); 2289 for (CFGBlock::succ_iterator I=item->succ_begin(), 2290 E=item->succ_end(); 2291 I != E; 2292 ++I) { 2293 if ((*I) && !live[(*I)->getBlockID()]) { 2294 live.set((*I)->getBlockID()); 2295 workq.push(*I); 2296 } 2297 } 2298 } 2299 return top; 2300} 2301 2302static int LineCmp(const void *p1, const void *p2) { 2303 SourceLocation *Line1 = (SourceLocation *)p1; 2304 SourceLocation *Line2 = (SourceLocation *)p2; 2305 return !(*Line1 < *Line2); 2306} 2307 2308namespace { 2309 struct ErrLoc { 2310 SourceLocation Loc; 2311 SourceRange R1; 2312 SourceRange R2; 2313 ErrLoc(SourceLocation l, SourceRange r1, SourceRange r2) 2314 : Loc(l), R1(r1), R2(r2) { } 2315 }; 2316} 2317 2318/// CheckUnreachable - Check for unreachable code. 2319void Sema::CheckUnreachable(AnalysisContext &AC) { 2320 unsigned count; 2321 // We avoid checking when there are errors, as the CFG won't faithfully match 2322 // the user's code. 2323 if (getDiagnostics().hasErrorOccurred()) 2324 return; 2325 if (Diags.getDiagnosticLevel(diag::warn_unreachable) == Diagnostic::Ignored) 2326 return; 2327 2328 CFG *cfg = AC.getCFG(); 2329 if (cfg == 0) 2330 return; 2331 2332 llvm::BitVector live(cfg->getNumBlockIDs()); 2333 // Mark all live things first. 2334 count = MarkLive(&cfg->getEntry(), live); 2335 2336 if (count == cfg->getNumBlockIDs()) 2337 // If there are no dead blocks, we're done. 2338 return; 2339 2340 SourceRange R1, R2; 2341 2342 llvm::SmallVector<ErrLoc, 24> lines; 2343 bool AddEHEdges = AC.getAddEHEdges(); 2344 // First, give warnings for blocks with no predecessors, as they 2345 // can't be part of a loop. 2346 for (CFG::iterator I = cfg->begin(), E = cfg->end(); I != E; ++I) { 2347 CFGBlock &b = **I; 2348 if (!live[b.getBlockID()]) { 2349 if (b.pred_begin() == b.pred_end()) { 2350 if (!AddEHEdges && b.getTerminator() 2351 && isa<CXXTryStmt>(b.getTerminator())) { 2352 // When not adding EH edges from calls, catch clauses 2353 // can otherwise seem dead. Avoid noting them as dead. 2354 count += MarkLive(&b, live); 2355 continue; 2356 } 2357 SourceLocation c = GetUnreachableLoc(b, R1, R2); 2358 if (!c.isValid()) { 2359 // Blocks without a location can't produce a warning, so don't mark 2360 // reachable blocks from here as live. 2361 live.set(b.getBlockID()); 2362 ++count; 2363 continue; 2364 } 2365 lines.push_back(ErrLoc(c, R1, R2)); 2366 // Avoid excessive errors by marking everything reachable from here 2367 count += MarkLive(&b, live); 2368 } 2369 } 2370 } 2371 2372 if (count < cfg->getNumBlockIDs()) { 2373 // And then give warnings for the tops of loops. 2374 for (CFG::iterator I = cfg->begin(), E = cfg->end(); I != E; ++I) { 2375 CFGBlock &b = **I; 2376 if (!live[b.getBlockID()]) 2377 // Avoid excessive errors by marking everything reachable from here 2378 lines.push_back(ErrLoc(MarkLiveTop(&b, live, 2379 Context.getSourceManager()), 2380 SourceRange(), SourceRange())); 2381 } 2382 } 2383 2384 llvm::array_pod_sort(lines.begin(), lines.end(), LineCmp); 2385 for (llvm::SmallVector<ErrLoc, 24>::iterator I = lines.begin(), 2386 E = lines.end(); 2387 I != E; 2388 ++I) 2389 if (I->Loc.isValid()) 2390 Diag(I->Loc, diag::warn_unreachable) << I->R1 << I->R2; 2391} 2392 2393/// CheckFallThrough - Check that we don't fall off the end of a 2394/// Statement that should return a value. 2395/// 2396/// \returns AlwaysFallThrough iff we always fall off the end of the statement, 2397/// MaybeFallThrough iff we might or might not fall off the end, 2398/// NeverFallThroughOrReturn iff we never fall off the end of the statement or 2399/// return. We assume NeverFallThrough iff we never fall off the end of the 2400/// statement but we may return. We assume that functions not marked noreturn 2401/// will return. 2402Sema::ControlFlowKind Sema::CheckFallThrough(AnalysisContext &AC) { 2403 CFG *cfg = AC.getCFG(); 2404 if (cfg == 0) 2405 // FIXME: This should be NeverFallThrough 2406 return NeverFallThroughOrReturn; 2407 2408 // The CFG leaves in dead things, and we don't want the dead code paths to 2409 // confuse us, so we mark all live things first. 2410 std::queue<CFGBlock*> workq; 2411 llvm::BitVector live(cfg->getNumBlockIDs()); 2412 unsigned count = MarkLive(&cfg->getEntry(), live); 2413 2414 bool AddEHEdges = AC.getAddEHEdges(); 2415 if (!AddEHEdges && count != cfg->getNumBlockIDs()) 2416 // When there are things remaining dead, and we didn't add EH edges 2417 // from CallExprs to the catch clauses, we have to go back and 2418 // mark them as live. 2419 for (CFG::iterator I = cfg->begin(), E = cfg->end(); I != E; ++I) { 2420 CFGBlock &b = **I; 2421 if (!live[b.getBlockID()]) { 2422 if (b.pred_begin() == b.pred_end()) { 2423 if (b.getTerminator() && isa<CXXTryStmt>(b.getTerminator())) 2424 // When not adding EH edges from calls, catch clauses 2425 // can otherwise seem dead. Avoid noting them as dead. 2426 count += MarkLive(&b, live); 2427 continue; 2428 } 2429 } 2430 } 2431 2432 // Now we know what is live, we check the live precessors of the exit block 2433 // and look for fall through paths, being careful to ignore normal returns, 2434 // and exceptional paths. 2435 bool HasLiveReturn = false; 2436 bool HasFakeEdge = false; 2437 bool HasPlainEdge = false; 2438 bool HasAbnormalEdge = false; 2439 for (CFGBlock::pred_iterator I=cfg->getExit().pred_begin(), 2440 E = cfg->getExit().pred_end(); 2441 I != E; 2442 ++I) { 2443 CFGBlock& B = **I; 2444 if (!live[B.getBlockID()]) 2445 continue; 2446 if (B.size() == 0) { 2447 if (B.getTerminator() && isa<CXXTryStmt>(B.getTerminator())) { 2448 HasAbnormalEdge = true; 2449 continue; 2450 } 2451 2452 // A labeled empty statement, or the entry block... 2453 HasPlainEdge = true; 2454 continue; 2455 } 2456 Stmt *S = B[B.size()-1]; 2457 if (isa<ReturnStmt>(S)) { 2458 HasLiveReturn = true; 2459 continue; 2460 } 2461 if (isa<ObjCAtThrowStmt>(S)) { 2462 HasFakeEdge = true; 2463 continue; 2464 } 2465 if (isa<CXXThrowExpr>(S)) { 2466 HasFakeEdge = true; 2467 continue; 2468 } 2469 if (const AsmStmt *AS = dyn_cast<AsmStmt>(S)) { 2470 if (AS->isMSAsm()) { 2471 HasFakeEdge = true; 2472 HasLiveReturn = true; 2473 continue; 2474 } 2475 } 2476 if (isa<CXXTryStmt>(S)) { 2477 HasAbnormalEdge = true; 2478 continue; 2479 } 2480 2481 bool NoReturnEdge = false; 2482 if (CallExpr *C = dyn_cast<CallExpr>(S)) { 2483 if (B.succ_begin()[0] != &cfg->getExit()) { 2484 HasAbnormalEdge = true; 2485 continue; 2486 } 2487 Expr *CEE = C->getCallee()->IgnoreParenCasts(); 2488 if (CEE->getType().getNoReturnAttr()) { 2489 NoReturnEdge = true; 2490 HasFakeEdge = true; 2491 } else if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(CEE)) { 2492 ValueDecl *VD = DRE->getDecl(); 2493 if (VD->hasAttr<NoReturnAttr>()) { 2494 NoReturnEdge = true; 2495 HasFakeEdge = true; 2496 } 2497 } 2498 } 2499 // FIXME: Add noreturn message sends. 2500 if (NoReturnEdge == false) 2501 HasPlainEdge = true; 2502 } 2503 if (!HasPlainEdge) { 2504 if (HasLiveReturn) 2505 return NeverFallThrough; 2506 return NeverFallThroughOrReturn; 2507 } 2508 if (HasAbnormalEdge || HasFakeEdge || HasLiveReturn) 2509 return MaybeFallThrough; 2510 // This says AlwaysFallThrough for calls to functions that are not marked 2511 // noreturn, that don't return. If people would like this warning to be more 2512 // accurate, such functions should be marked as noreturn. 2513 return AlwaysFallThrough; 2514} 2515 2516/// CheckFallThroughForFunctionDef - Check that we don't fall off the end of a 2517/// function that should return a value. Check that we don't fall off the end 2518/// of a noreturn function. We assume that functions and blocks not marked 2519/// noreturn will return. 2520void Sema::CheckFallThroughForFunctionDef(Decl *D, Stmt *Body, 2521 AnalysisContext &AC) { 2522 // FIXME: Would be nice if we had a better way to control cascading errors, 2523 // but for now, avoid them. The problem is that when Parse sees: 2524 // int foo() { return a; } 2525 // The return is eaten and the Sema code sees just: 2526 // int foo() { } 2527 // which this code would then warn about. 2528 if (getDiagnostics().hasErrorOccurred()) 2529 return; 2530 2531 bool ReturnsVoid = false; 2532 bool HasNoReturn = false; 2533 if (FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) { 2534 // For function templates, class templates and member function templates 2535 // we'll do the analysis at instantiation time. 2536 if (FD->isDependentContext()) 2537 return; 2538 2539 if (FD->getResultType()->isVoidType()) 2540 ReturnsVoid = true; 2541 if (FD->hasAttr<NoReturnAttr>() || 2542 FD->getType()->getAs<FunctionType>()->getNoReturnAttr()) 2543 HasNoReturn = true; 2544 } else if (ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(D)) { 2545 if (MD->getResultType()->isVoidType()) 2546 ReturnsVoid = true; 2547 if (MD->hasAttr<NoReturnAttr>()) 2548 HasNoReturn = true; 2549 } 2550 2551 // Short circuit for compilation speed. 2552 if ((Diags.getDiagnosticLevel(diag::warn_maybe_falloff_nonvoid_function) 2553 == Diagnostic::Ignored || ReturnsVoid) 2554 && (Diags.getDiagnosticLevel(diag::warn_noreturn_function_has_return_expr) 2555 == Diagnostic::Ignored || !HasNoReturn) 2556 && (Diags.getDiagnosticLevel(diag::warn_suggest_noreturn_block) 2557 == Diagnostic::Ignored || !ReturnsVoid)) 2558 return; 2559 // FIXME: Function try block 2560 if (CompoundStmt *Compound = dyn_cast<CompoundStmt>(Body)) { 2561 switch (CheckFallThrough(AC)) { 2562 case MaybeFallThrough: 2563 if (HasNoReturn) 2564 Diag(Compound->getRBracLoc(), diag::warn_falloff_noreturn_function); 2565 else if (!ReturnsVoid) 2566 Diag(Compound->getRBracLoc(),diag::warn_maybe_falloff_nonvoid_function); 2567 break; 2568 case AlwaysFallThrough: 2569 if (HasNoReturn) 2570 Diag(Compound->getRBracLoc(), diag::warn_falloff_noreturn_function); 2571 else if (!ReturnsVoid) 2572 Diag(Compound->getRBracLoc(), diag::warn_falloff_nonvoid_function); 2573 break; 2574 case NeverFallThroughOrReturn: 2575 if (ReturnsVoid && !HasNoReturn) 2576 Diag(Compound->getLBracLoc(), diag::warn_suggest_noreturn_function); 2577 break; 2578 case NeverFallThrough: 2579 break; 2580 } 2581 } 2582} 2583 2584/// CheckFallThroughForBlock - Check that we don't fall off the end of a block 2585/// that should return a value. Check that we don't fall off the end of a 2586/// noreturn block. We assume that functions and blocks not marked noreturn 2587/// will return. 2588void Sema::CheckFallThroughForBlock(QualType BlockTy, Stmt *Body, 2589 AnalysisContext &AC) { 2590 // FIXME: Would be nice if we had a better way to control cascading errors, 2591 // but for now, avoid them. The problem is that when Parse sees: 2592 // int foo() { return a; } 2593 // The return is eaten and the Sema code sees just: 2594 // int foo() { } 2595 // which this code would then warn about. 2596 if (getDiagnostics().hasErrorOccurred()) 2597 return; 2598 bool ReturnsVoid = false; 2599 bool HasNoReturn = false; 2600 if (const FunctionType *FT =BlockTy->getPointeeType()->getAs<FunctionType>()){ 2601 if (FT->getResultType()->isVoidType()) 2602 ReturnsVoid = true; 2603 if (FT->getNoReturnAttr()) 2604 HasNoReturn = true; 2605 } 2606 2607 // Short circuit for compilation speed. 2608 if (ReturnsVoid 2609 && !HasNoReturn 2610 && (Diags.getDiagnosticLevel(diag::warn_suggest_noreturn_block) 2611 == Diagnostic::Ignored || !ReturnsVoid)) 2612 return; 2613 // FIXME: Funtion try block 2614 if (CompoundStmt *Compound = dyn_cast<CompoundStmt>(Body)) { 2615 switch (CheckFallThrough(AC)) { 2616 case MaybeFallThrough: 2617 if (HasNoReturn) 2618 Diag(Compound->getRBracLoc(), diag::err_noreturn_block_has_return_expr); 2619 else if (!ReturnsVoid) 2620 Diag(Compound->getRBracLoc(), diag::err_maybe_falloff_nonvoid_block); 2621 break; 2622 case AlwaysFallThrough: 2623 if (HasNoReturn) 2624 Diag(Compound->getRBracLoc(), diag::err_noreturn_block_has_return_expr); 2625 else if (!ReturnsVoid) 2626 Diag(Compound->getRBracLoc(), diag::err_falloff_nonvoid_block); 2627 break; 2628 case NeverFallThroughOrReturn: 2629 if (ReturnsVoid) 2630 Diag(Compound->getLBracLoc(), diag::warn_suggest_noreturn_block); 2631 break; 2632 case NeverFallThrough: 2633 break; 2634 } 2635 } 2636} 2637 2638/// CheckParmsForFunctionDef - Check that the parameters of the given 2639/// function are appropriate for the definition of a function. This 2640/// takes care of any checks that cannot be performed on the 2641/// declaration itself, e.g., that the types of each of the function 2642/// parameters are complete. 2643bool Sema::CheckParmsForFunctionDef(FunctionDecl *FD) { 2644 bool HasInvalidParm = false; 2645 for (unsigned p = 0, NumParams = FD->getNumParams(); p < NumParams; ++p) { 2646 ParmVarDecl *Param = FD->getParamDecl(p); 2647 2648 // C99 6.7.5.3p4: the parameters in a parameter type list in a 2649 // function declarator that is part of a function definition of 2650 // that function shall not have incomplete type. 2651 // 2652 // This is also C++ [dcl.fct]p6. 2653 if (!Param->isInvalidDecl() && 2654 RequireCompleteType(Param->getLocation(), Param->getType(), 2655 diag::err_typecheck_decl_incomplete_type)) { 2656 Param->setInvalidDecl(); 2657 HasInvalidParm = true; 2658 } 2659 2660 // C99 6.9.1p5: If the declarator includes a parameter type list, the 2661 // declaration of each parameter shall include an identifier. 2662 if (Param->getIdentifier() == 0 && 2663 !Param->isImplicit() && 2664 !getLangOptions().CPlusPlus) 2665 Diag(Param->getLocation(), diag::err_parameter_name_omitted); 2666 2667 // C99 6.7.5.3p12: 2668 // If the function declarator is not part of a definition of that 2669 // function, parameters may have incomplete type and may use the [*] 2670 // notation in their sequences of declarator specifiers to specify 2671 // variable length array types. 2672 QualType PType = Param->getOriginalType(); 2673 if (const ArrayType *AT = Context.getAsArrayType(PType)) { 2674 if (AT->getSizeModifier() == ArrayType::Star) { 2675 // FIXME: This diagnosic should point the the '[*]' if source-location 2676 // information is added for it. 2677 Diag(Param->getLocation(), diag::err_array_star_in_function_definition); 2678 } 2679 } 2680 2681 if (getLangOptions().CPlusPlus) 2682 if (const RecordType *RT = Param->getType()->getAs<RecordType>()) 2683 FinalizeVarWithDestructor(Param, RT); 2684 } 2685 2686 return HasInvalidParm; 2687} 2688