SemaChecking.cpp revision f762905bdefad77f91c7c6782a9c17e6b274d393
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/Analyses/FormatString.h" 17#include "clang/AST/ASTContext.h" 18#include "clang/AST/CharUnits.h" 19#include "clang/AST/DeclObjC.h" 20#include "clang/AST/ExprCXX.h" 21#include "clang/AST/ExprObjC.h" 22#include "clang/AST/DeclObjC.h" 23#include "clang/AST/StmtCXX.h" 24#include "clang/AST/StmtObjC.h" 25#include "clang/Lex/LiteralSupport.h" 26#include "clang/Lex/Preprocessor.h" 27#include "llvm/ADT/BitVector.h" 28#include "llvm/ADT/STLExtras.h" 29#include "llvm/ADT/StringExtras.h" 30#include "llvm/Support/raw_ostream.h" 31#include "clang/Basic/TargetBuiltins.h" 32#include "clang/Basic/TargetInfo.h" 33#include <limits> 34using namespace clang; 35 36/// getLocationOfStringLiteralByte - Return a source location that points to the 37/// specified byte of the specified string literal. 38/// 39/// Strings are amazingly complex. They can be formed from multiple tokens and 40/// can have escape sequences in them in addition to the usual trigraph and 41/// escaped newline business. This routine handles this complexity. 42/// 43SourceLocation Sema::getLocationOfStringLiteralByte(const StringLiteral *SL, 44 unsigned ByteNo) const { 45 assert(!SL->isWide() && "This doesn't work for wide strings yet"); 46 47 // Loop over all of the tokens in this string until we find the one that 48 // contains the byte we're looking for. 49 unsigned TokNo = 0; 50 while (1) { 51 assert(TokNo < SL->getNumConcatenated() && "Invalid byte number!"); 52 SourceLocation StrTokLoc = SL->getStrTokenLoc(TokNo); 53 54 // Get the spelling of the string so that we can get the data that makes up 55 // the string literal, not the identifier for the macro it is potentially 56 // expanded through. 57 SourceLocation StrTokSpellingLoc = SourceMgr.getSpellingLoc(StrTokLoc); 58 59 // Re-lex the token to get its length and original spelling. 60 std::pair<FileID, unsigned> LocInfo = 61 SourceMgr.getDecomposedLoc(StrTokSpellingLoc); 62 bool Invalid = false; 63 llvm::StringRef Buffer = SourceMgr.getBufferData(LocInfo.first, &Invalid); 64 if (Invalid) 65 return StrTokSpellingLoc; 66 67 const char *StrData = Buffer.data()+LocInfo.second; 68 69 // Create a langops struct and enable trigraphs. This is sufficient for 70 // relexing tokens. 71 LangOptions LangOpts; 72 LangOpts.Trigraphs = true; 73 74 // Create a lexer starting at the beginning of this token. 75 Lexer TheLexer(StrTokSpellingLoc, LangOpts, Buffer.begin(), StrData, 76 Buffer.end()); 77 Token TheTok; 78 TheLexer.LexFromRawLexer(TheTok); 79 80 // Use the StringLiteralParser to compute the length of the string in bytes. 81 StringLiteralParser SLP(&TheTok, 1, PP, /*Complain=*/false); 82 unsigned TokNumBytes = SLP.GetStringLength(); 83 84 // If the byte is in this token, return the location of the byte. 85 if (ByteNo < TokNumBytes || 86 (ByteNo == TokNumBytes && TokNo == SL->getNumConcatenated())) { 87 unsigned Offset = 88 StringLiteralParser::getOffsetOfStringByte(TheTok, ByteNo, PP, 89 /*Complain=*/false); 90 91 // Now that we know the offset of the token in the spelling, use the 92 // preprocessor to get the offset in the original source. 93 return PP.AdvanceToTokenCharacter(StrTokLoc, Offset); 94 } 95 96 // Move to the next string token. 97 ++TokNo; 98 ByteNo -= TokNumBytes; 99 } 100} 101 102/// CheckablePrintfAttr - does a function call have a "printf" attribute 103/// and arguments that merit checking? 104bool Sema::CheckablePrintfAttr(const FormatAttr *Format, CallExpr *TheCall) { 105 if (Format->getType() == "printf") return true; 106 if (Format->getType() == "printf0") { 107 // printf0 allows null "format" string; if so don't check format/args 108 unsigned format_idx = Format->getFormatIdx() - 1; 109 // Does the index refer to the implicit object argument? 110 if (isa<CXXMemberCallExpr>(TheCall)) { 111 if (format_idx == 0) 112 return false; 113 --format_idx; 114 } 115 if (format_idx < TheCall->getNumArgs()) { 116 Expr *Format = TheCall->getArg(format_idx)->IgnoreParenCasts(); 117 if (!Format->isNullPointerConstant(Context, 118 Expr::NPC_ValueDependentIsNull)) 119 return true; 120 } 121 } 122 return false; 123} 124 125Action::OwningExprResult 126Sema::CheckBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) { 127 OwningExprResult TheCallResult(Owned(TheCall)); 128 129 switch (BuiltinID) { 130 case Builtin::BI__builtin___CFStringMakeConstantString: 131 assert(TheCall->getNumArgs() == 1 && 132 "Wrong # arguments to builtin CFStringMakeConstantString"); 133 if (CheckObjCString(TheCall->getArg(0))) 134 return ExprError(); 135 break; 136 case Builtin::BI__builtin_stdarg_start: 137 case Builtin::BI__builtin_va_start: 138 if (SemaBuiltinVAStart(TheCall)) 139 return ExprError(); 140 break; 141 case Builtin::BI__builtin_isgreater: 142 case Builtin::BI__builtin_isgreaterequal: 143 case Builtin::BI__builtin_isless: 144 case Builtin::BI__builtin_islessequal: 145 case Builtin::BI__builtin_islessgreater: 146 case Builtin::BI__builtin_isunordered: 147 if (SemaBuiltinUnorderedCompare(TheCall)) 148 return ExprError(); 149 break; 150 case Builtin::BI__builtin_fpclassify: 151 if (SemaBuiltinFPClassification(TheCall, 6)) 152 return ExprError(); 153 break; 154 case Builtin::BI__builtin_isfinite: 155 case Builtin::BI__builtin_isinf: 156 case Builtin::BI__builtin_isinf_sign: 157 case Builtin::BI__builtin_isnan: 158 case Builtin::BI__builtin_isnormal: 159 if (SemaBuiltinFPClassification(TheCall, 1)) 160 return ExprError(); 161 break; 162 case Builtin::BI__builtin_return_address: 163 case Builtin::BI__builtin_frame_address: { 164 llvm::APSInt Result; 165 if (SemaBuiltinConstantArg(TheCall, 0, Result)) 166 return ExprError(); 167 break; 168 } 169 case Builtin::BI__builtin_eh_return_data_regno: { 170 llvm::APSInt Result; 171 if (SemaBuiltinConstantArg(TheCall, 0, Result)) 172 return ExprError(); 173 break; 174 } 175 case Builtin::BI__builtin_shufflevector: 176 return SemaBuiltinShuffleVector(TheCall); 177 // TheCall will be freed by the smart pointer here, but that's fine, since 178 // SemaBuiltinShuffleVector guts it, but then doesn't release it. 179 case Builtin::BI__builtin_prefetch: 180 if (SemaBuiltinPrefetch(TheCall)) 181 return ExprError(); 182 break; 183 case Builtin::BI__builtin_object_size: 184 if (SemaBuiltinObjectSize(TheCall)) 185 return ExprError(); 186 break; 187 case Builtin::BI__builtin_longjmp: 188 if (SemaBuiltinLongjmp(TheCall)) 189 return ExprError(); 190 break; 191 case Builtin::BI__sync_fetch_and_add: 192 case Builtin::BI__sync_fetch_and_sub: 193 case Builtin::BI__sync_fetch_and_or: 194 case Builtin::BI__sync_fetch_and_and: 195 case Builtin::BI__sync_fetch_and_xor: 196 case Builtin::BI__sync_add_and_fetch: 197 case Builtin::BI__sync_sub_and_fetch: 198 case Builtin::BI__sync_and_and_fetch: 199 case Builtin::BI__sync_or_and_fetch: 200 case Builtin::BI__sync_xor_and_fetch: 201 case Builtin::BI__sync_val_compare_and_swap: 202 case Builtin::BI__sync_bool_compare_and_swap: 203 case Builtin::BI__sync_lock_test_and_set: 204 case Builtin::BI__sync_lock_release: 205 return SemaBuiltinAtomicOverloaded(move(TheCallResult)); 206 } 207 208 // Since the target specific builtins for each arch overlap, only check those 209 // of the arch we are compiling for. 210 if (BuiltinID >= Builtin::FirstTSBuiltin) { 211 switch (Context.Target.getTriple().getArch()) { 212 case llvm::Triple::arm: 213 case llvm::Triple::thumb: 214 if (CheckARMBuiltinFunctionCall(BuiltinID, TheCall)) 215 return ExprError(); 216 break; 217 case llvm::Triple::x86: 218 case llvm::Triple::x86_64: 219 if (CheckX86BuiltinFunctionCall(BuiltinID, TheCall)) 220 return ExprError(); 221 break; 222 default: 223 break; 224 } 225 } 226 227 return move(TheCallResult); 228} 229 230bool Sema::CheckX86BuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) { 231 switch (BuiltinID) { 232 case X86::BI__builtin_ia32_palignr128: 233 case X86::BI__builtin_ia32_palignr: { 234 llvm::APSInt Result; 235 if (SemaBuiltinConstantArg(TheCall, 2, Result)) 236 return true; 237 break; 238 } 239 } 240 return false; 241} 242 243// Get the valid immediate range for the specified NEON type code. 244static unsigned RFT(unsigned t, bool shift = false) { 245 bool quad = t & 0x10; 246 247 switch (t & 0x7) { 248 case 0: // i8 249 return shift ? 7 : (8 << (int)quad) - 1; 250 case 1: // i16 251 return shift ? 15 : (4 << (int)quad) - 1; 252 case 2: // i32 253 return shift ? 31 : (2 << (int)quad) - 1; 254 case 3: // i64 255 return shift ? 63 : (1 << (int)quad) - 1; 256 case 4: // f32 257 assert(!shift && "cannot shift float types!"); 258 return (2 << (int)quad) - 1; 259 case 5: // poly8 260 assert(!shift && "cannot shift polynomial types!"); 261 return (8 << (int)quad) - 1; 262 case 6: // poly16 263 assert(!shift && "cannot shift polynomial types!"); 264 return (4 << (int)quad) - 1; 265 case 7: // float16 266 assert(!shift && "cannot shift float types!"); 267 return (4 << (int)quad) - 1; 268 } 269 return 0; 270} 271 272bool Sema::CheckARMBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) { 273 llvm::APSInt Result; 274 275 unsigned mask = 0; 276 unsigned TV = 0; 277 switch (BuiltinID) { 278#define GET_NEON_OVERLOAD_CHECK 279#include "clang/Basic/arm_neon.inc" 280#undef GET_NEON_OVERLOAD_CHECK 281 } 282 283 // For NEON intrinsics which are overloaded on vector element type, validate 284 // the immediate which specifies which variant to emit. 285 if (mask) { 286 unsigned ArgNo = TheCall->getNumArgs()-1; 287 if (SemaBuiltinConstantArg(TheCall, ArgNo, Result)) 288 return true; 289 290 TV = Result.getLimitedValue(32); 291 if ((TV > 31) || (mask & (1 << TV)) == 0) 292 return Diag(TheCall->getLocStart(), diag::err_invalid_neon_type_code) 293 << TheCall->getArg(ArgNo)->getSourceRange(); 294 } 295 296 // For NEON intrinsics which take an immediate value as part of the 297 // instruction, range check them here. 298 unsigned i = 0, l = 0, u = 0; 299 switch (BuiltinID) { 300 default: return false; 301#define GET_NEON_IMMEDIATE_CHECK 302#include "clang/Basic/arm_neon.inc" 303#undef GET_NEON_IMMEDIATE_CHECK 304 }; 305 306 // Check that the immediate argument is actually a constant. 307 if (SemaBuiltinConstantArg(TheCall, i, Result)) 308 return true; 309 310 // Range check against the upper/lower values for this isntruction. 311 unsigned Val = Result.getZExtValue(); 312 if (Val < l || Val > (u + l)) 313 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 314 << llvm::utostr(l) << llvm::utostr(u+l) 315 << TheCall->getArg(i)->getSourceRange(); 316 317 return false; 318} 319 320/// CheckFunctionCall - Check a direct function call for various correctness 321/// and safety properties not strictly enforced by the C type system. 322bool Sema::CheckFunctionCall(FunctionDecl *FDecl, CallExpr *TheCall) { 323 // Get the IdentifierInfo* for the called function. 324 IdentifierInfo *FnInfo = FDecl->getIdentifier(); 325 326 // None of the checks below are needed for functions that don't have 327 // simple names (e.g., C++ conversion functions). 328 if (!FnInfo) 329 return false; 330 331 // FIXME: This mechanism should be abstracted to be less fragile and 332 // more efficient. For example, just map function ids to custom 333 // handlers. 334 335 // Printf checking. 336 if (const FormatAttr *Format = FDecl->getAttr<FormatAttr>()) { 337 const bool b = Format->getType() == "scanf"; 338 if (b || CheckablePrintfAttr(Format, TheCall)) { 339 bool HasVAListArg = Format->getFirstArg() == 0; 340 CheckPrintfScanfArguments(TheCall, HasVAListArg, 341 Format->getFormatIdx() - 1, 342 HasVAListArg ? 0 : Format->getFirstArg() - 1, 343 !b); 344 } 345 } 346 347 for (const NonNullAttr *NonNull = FDecl->getAttr<NonNullAttr>(); NonNull; 348 NonNull = NonNull->getNext<NonNullAttr>()) 349 CheckNonNullArguments(NonNull, TheCall); 350 351 return false; 352} 353 354bool Sema::CheckBlockCall(NamedDecl *NDecl, CallExpr *TheCall) { 355 // Printf checking. 356 const FormatAttr *Format = NDecl->getAttr<FormatAttr>(); 357 if (!Format) 358 return false; 359 360 const VarDecl *V = dyn_cast<VarDecl>(NDecl); 361 if (!V) 362 return false; 363 364 QualType Ty = V->getType(); 365 if (!Ty->isBlockPointerType()) 366 return false; 367 368 const bool b = Format->getType() == "scanf"; 369 if (!b && !CheckablePrintfAttr(Format, TheCall)) 370 return false; 371 372 bool HasVAListArg = Format->getFirstArg() == 0; 373 CheckPrintfScanfArguments(TheCall, HasVAListArg, Format->getFormatIdx() - 1, 374 HasVAListArg ? 0 : Format->getFirstArg() - 1, !b); 375 376 return false; 377} 378 379/// SemaBuiltinAtomicOverloaded - We have a call to a function like 380/// __sync_fetch_and_add, which is an overloaded function based on the pointer 381/// type of its first argument. The main ActOnCallExpr routines have already 382/// promoted the types of arguments because all of these calls are prototyped as 383/// void(...). 384/// 385/// This function goes through and does final semantic checking for these 386/// builtins, 387Sema::OwningExprResult 388Sema::SemaBuiltinAtomicOverloaded(OwningExprResult TheCallResult) { 389 CallExpr *TheCall = (CallExpr *)TheCallResult.get(); 390 DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts()); 391 FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl()); 392 393 // Ensure that we have at least one argument to do type inference from. 394 if (TheCall->getNumArgs() < 1) { 395 Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args_at_least) 396 << 0 << 1 << TheCall->getNumArgs() 397 << TheCall->getCallee()->getSourceRange(); 398 return ExprError(); 399 } 400 401 // Inspect the first argument of the atomic builtin. This should always be 402 // a pointer type, whose element is an integral scalar or pointer type. 403 // Because it is a pointer type, we don't have to worry about any implicit 404 // casts here. 405 // FIXME: We don't allow floating point scalars as input. 406 Expr *FirstArg = TheCall->getArg(0); 407 if (!FirstArg->getType()->isPointerType()) { 408 Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer) 409 << FirstArg->getType() << FirstArg->getSourceRange(); 410 return ExprError(); 411 } 412 413 QualType ValType = 414 FirstArg->getType()->getAs<PointerType>()->getPointeeType(); 415 if (!ValType->isIntegerType() && !ValType->isPointerType() && 416 !ValType->isBlockPointerType()) { 417 Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer_intptr) 418 << FirstArg->getType() << FirstArg->getSourceRange(); 419 return ExprError(); 420 } 421 422 // The majority of builtins return a value, but a few have special return 423 // types, so allow them to override appropriately below. 424 QualType ResultType = ValType; 425 426 // We need to figure out which concrete builtin this maps onto. For example, 427 // __sync_fetch_and_add with a 2 byte object turns into 428 // __sync_fetch_and_add_2. 429#define BUILTIN_ROW(x) \ 430 { Builtin::BI##x##_1, Builtin::BI##x##_2, Builtin::BI##x##_4, \ 431 Builtin::BI##x##_8, Builtin::BI##x##_16 } 432 433 static const unsigned BuiltinIndices[][5] = { 434 BUILTIN_ROW(__sync_fetch_and_add), 435 BUILTIN_ROW(__sync_fetch_and_sub), 436 BUILTIN_ROW(__sync_fetch_and_or), 437 BUILTIN_ROW(__sync_fetch_and_and), 438 BUILTIN_ROW(__sync_fetch_and_xor), 439 440 BUILTIN_ROW(__sync_add_and_fetch), 441 BUILTIN_ROW(__sync_sub_and_fetch), 442 BUILTIN_ROW(__sync_and_and_fetch), 443 BUILTIN_ROW(__sync_or_and_fetch), 444 BUILTIN_ROW(__sync_xor_and_fetch), 445 446 BUILTIN_ROW(__sync_val_compare_and_swap), 447 BUILTIN_ROW(__sync_bool_compare_and_swap), 448 BUILTIN_ROW(__sync_lock_test_and_set), 449 BUILTIN_ROW(__sync_lock_release) 450 }; 451#undef BUILTIN_ROW 452 453 // Determine the index of the size. 454 unsigned SizeIndex; 455 switch (Context.getTypeSizeInChars(ValType).getQuantity()) { 456 case 1: SizeIndex = 0; break; 457 case 2: SizeIndex = 1; break; 458 case 4: SizeIndex = 2; break; 459 case 8: SizeIndex = 3; break; 460 case 16: SizeIndex = 4; break; 461 default: 462 Diag(DRE->getLocStart(), diag::err_atomic_builtin_pointer_size) 463 << FirstArg->getType() << FirstArg->getSourceRange(); 464 return ExprError(); 465 } 466 467 // Each of these builtins has one pointer argument, followed by some number of 468 // values (0, 1 or 2) followed by a potentially empty varags list of stuff 469 // that we ignore. Find out which row of BuiltinIndices to read from as well 470 // as the number of fixed args. 471 unsigned BuiltinID = FDecl->getBuiltinID(); 472 unsigned BuiltinIndex, NumFixed = 1; 473 switch (BuiltinID) { 474 default: assert(0 && "Unknown overloaded atomic builtin!"); 475 case Builtin::BI__sync_fetch_and_add: BuiltinIndex = 0; break; 476 case Builtin::BI__sync_fetch_and_sub: BuiltinIndex = 1; break; 477 case Builtin::BI__sync_fetch_and_or: BuiltinIndex = 2; break; 478 case Builtin::BI__sync_fetch_and_and: BuiltinIndex = 3; break; 479 case Builtin::BI__sync_fetch_and_xor: BuiltinIndex = 4; break; 480 481 case Builtin::BI__sync_add_and_fetch: BuiltinIndex = 5; break; 482 case Builtin::BI__sync_sub_and_fetch: BuiltinIndex = 6; break; 483 case Builtin::BI__sync_and_and_fetch: BuiltinIndex = 7; break; 484 case Builtin::BI__sync_or_and_fetch: BuiltinIndex = 8; break; 485 case Builtin::BI__sync_xor_and_fetch: BuiltinIndex = 9; break; 486 487 case Builtin::BI__sync_val_compare_and_swap: 488 BuiltinIndex = 10; 489 NumFixed = 2; 490 break; 491 case Builtin::BI__sync_bool_compare_and_swap: 492 BuiltinIndex = 11; 493 NumFixed = 2; 494 ResultType = Context.BoolTy; 495 break; 496 case Builtin::BI__sync_lock_test_and_set: BuiltinIndex = 12; break; 497 case Builtin::BI__sync_lock_release: 498 BuiltinIndex = 13; 499 NumFixed = 0; 500 ResultType = Context.VoidTy; 501 break; 502 } 503 504 // Now that we know how many fixed arguments we expect, first check that we 505 // have at least that many. 506 if (TheCall->getNumArgs() < 1+NumFixed) { 507 Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args_at_least) 508 << 0 << 1+NumFixed << TheCall->getNumArgs() 509 << TheCall->getCallee()->getSourceRange(); 510 return ExprError(); 511 } 512 513 // Get the decl for the concrete builtin from this, we can tell what the 514 // concrete integer type we should convert to is. 515 unsigned NewBuiltinID = BuiltinIndices[BuiltinIndex][SizeIndex]; 516 const char *NewBuiltinName = Context.BuiltinInfo.GetName(NewBuiltinID); 517 IdentifierInfo *NewBuiltinII = PP.getIdentifierInfo(NewBuiltinName); 518 FunctionDecl *NewBuiltinDecl = 519 cast<FunctionDecl>(LazilyCreateBuiltin(NewBuiltinII, NewBuiltinID, 520 TUScope, false, DRE->getLocStart())); 521 522 // The first argument is by definition correct, we use it's type as the type 523 // of the entire operation. Walk the remaining arguments promoting them to 524 // the deduced value type. 525 for (unsigned i = 0; i != NumFixed; ++i) { 526 Expr *Arg = TheCall->getArg(i+1); 527 528 // If the argument is an implicit cast, then there was a promotion due to 529 // "...", just remove it now. 530 if (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Arg)) { 531 Arg = ICE->getSubExpr(); 532 ICE->setSubExpr(0); 533 TheCall->setArg(i+1, Arg); 534 } 535 536 // GCC does an implicit conversion to the pointer or integer ValType. This 537 // can fail in some cases (1i -> int**), check for this error case now. 538 CastExpr::CastKind Kind = CastExpr::CK_Unknown; 539 CXXBaseSpecifierArray BasePath; 540 if (CheckCastTypes(Arg->getSourceRange(), ValType, Arg, Kind, BasePath)) 541 return ExprError(); 542 543 // Okay, we have something that *can* be converted to the right type. Check 544 // to see if there is a potentially weird extension going on here. This can 545 // happen when you do an atomic operation on something like an char* and 546 // pass in 42. The 42 gets converted to char. This is even more strange 547 // for things like 45.123 -> char, etc. 548 // FIXME: Do this check. 549 ImpCastExprToType(Arg, ValType, Kind); 550 TheCall->setArg(i+1, Arg); 551 } 552 553 // Switch the DeclRefExpr to refer to the new decl. 554 DRE->setDecl(NewBuiltinDecl); 555 DRE->setType(NewBuiltinDecl->getType()); 556 557 // Set the callee in the CallExpr. 558 // FIXME: This leaks the original parens and implicit casts. 559 Expr *PromotedCall = DRE; 560 UsualUnaryConversions(PromotedCall); 561 TheCall->setCallee(PromotedCall); 562 563 // Change the result type of the call to match the original value type. This 564 // is arbitrary, but the codegen for these builtins ins design to handle it 565 // gracefully. 566 TheCall->setType(ResultType); 567 568 return move(TheCallResult); 569} 570 571 572/// CheckObjCString - Checks that the argument to the builtin 573/// CFString constructor is correct 574/// FIXME: GCC currently emits the following warning: 575/// "warning: input conversion stopped due to an input byte that does not 576/// belong to the input codeset UTF-8" 577/// Note: It might also make sense to do the UTF-16 conversion here (would 578/// simplify the backend). 579bool Sema::CheckObjCString(Expr *Arg) { 580 Arg = Arg->IgnoreParenCasts(); 581 StringLiteral *Literal = dyn_cast<StringLiteral>(Arg); 582 583 if (!Literal || Literal->isWide()) { 584 Diag(Arg->getLocStart(), diag::err_cfstring_literal_not_string_constant) 585 << Arg->getSourceRange(); 586 return true; 587 } 588 589 const char *Data = Literal->getStrData(); 590 unsigned Length = Literal->getByteLength(); 591 592 for (unsigned i = 0; i < Length; ++i) { 593 if (!Data[i]) { 594 Diag(getLocationOfStringLiteralByte(Literal, i), 595 diag::warn_cfstring_literal_contains_nul_character) 596 << Arg->getSourceRange(); 597 break; 598 } 599 } 600 601 return false; 602} 603 604/// SemaBuiltinVAStart - Check the arguments to __builtin_va_start for validity. 605/// Emit an error and return true on failure, return false on success. 606bool Sema::SemaBuiltinVAStart(CallExpr *TheCall) { 607 Expr *Fn = TheCall->getCallee(); 608 if (TheCall->getNumArgs() > 2) { 609 Diag(TheCall->getArg(2)->getLocStart(), 610 diag::err_typecheck_call_too_many_args) 611 << 0 /*function call*/ << 2 << TheCall->getNumArgs() 612 << Fn->getSourceRange() 613 << SourceRange(TheCall->getArg(2)->getLocStart(), 614 (*(TheCall->arg_end()-1))->getLocEnd()); 615 return true; 616 } 617 618 if (TheCall->getNumArgs() < 2) { 619 return Diag(TheCall->getLocEnd(), 620 diag::err_typecheck_call_too_few_args_at_least) 621 << 0 /*function call*/ << 2 << TheCall->getNumArgs(); 622 } 623 624 // Determine whether the current function is variadic or not. 625 BlockScopeInfo *CurBlock = getCurBlock(); 626 bool isVariadic; 627 if (CurBlock) 628 isVariadic = CurBlock->TheDecl->isVariadic(); 629 else if (FunctionDecl *FD = getCurFunctionDecl()) 630 isVariadic = FD->isVariadic(); 631 else 632 isVariadic = getCurMethodDecl()->isVariadic(); 633 634 if (!isVariadic) { 635 Diag(Fn->getLocStart(), diag::err_va_start_used_in_non_variadic_function); 636 return true; 637 } 638 639 // Verify that the second argument to the builtin is the last argument of the 640 // current function or method. 641 bool SecondArgIsLastNamedArgument = false; 642 const Expr *Arg = TheCall->getArg(1)->IgnoreParenCasts(); 643 644 if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Arg)) { 645 if (const ParmVarDecl *PV = dyn_cast<ParmVarDecl>(DR->getDecl())) { 646 // FIXME: This isn't correct for methods (results in bogus warning). 647 // Get the last formal in the current function. 648 const ParmVarDecl *LastArg; 649 if (CurBlock) 650 LastArg = *(CurBlock->TheDecl->param_end()-1); 651 else if (FunctionDecl *FD = getCurFunctionDecl()) 652 LastArg = *(FD->param_end()-1); 653 else 654 LastArg = *(getCurMethodDecl()->param_end()-1); 655 SecondArgIsLastNamedArgument = PV == LastArg; 656 } 657 } 658 659 if (!SecondArgIsLastNamedArgument) 660 Diag(TheCall->getArg(1)->getLocStart(), 661 diag::warn_second_parameter_of_va_start_not_last_named_argument); 662 return false; 663} 664 665/// SemaBuiltinUnorderedCompare - Handle functions like __builtin_isgreater and 666/// friends. This is declared to take (...), so we have to check everything. 667bool Sema::SemaBuiltinUnorderedCompare(CallExpr *TheCall) { 668 if (TheCall->getNumArgs() < 2) 669 return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args) 670 << 0 << 2 << TheCall->getNumArgs()/*function call*/; 671 if (TheCall->getNumArgs() > 2) 672 return Diag(TheCall->getArg(2)->getLocStart(), 673 diag::err_typecheck_call_too_many_args) 674 << 0 /*function call*/ << 2 << TheCall->getNumArgs() 675 << SourceRange(TheCall->getArg(2)->getLocStart(), 676 (*(TheCall->arg_end()-1))->getLocEnd()); 677 678 Expr *OrigArg0 = TheCall->getArg(0); 679 Expr *OrigArg1 = TheCall->getArg(1); 680 681 // Do standard promotions between the two arguments, returning their common 682 // type. 683 QualType Res = UsualArithmeticConversions(OrigArg0, OrigArg1, false); 684 685 // Make sure any conversions are pushed back into the call; this is 686 // type safe since unordered compare builtins are declared as "_Bool 687 // foo(...)". 688 TheCall->setArg(0, OrigArg0); 689 TheCall->setArg(1, OrigArg1); 690 691 if (OrigArg0->isTypeDependent() || OrigArg1->isTypeDependent()) 692 return false; 693 694 // If the common type isn't a real floating type, then the arguments were 695 // invalid for this operation. 696 if (!Res->isRealFloatingType()) 697 return Diag(OrigArg0->getLocStart(), 698 diag::err_typecheck_call_invalid_ordered_compare) 699 << OrigArg0->getType() << OrigArg1->getType() 700 << SourceRange(OrigArg0->getLocStart(), OrigArg1->getLocEnd()); 701 702 return false; 703} 704 705/// SemaBuiltinSemaBuiltinFPClassification - Handle functions like 706/// __builtin_isnan and friends. This is declared to take (...), so we have 707/// to check everything. We expect the last argument to be a floating point 708/// value. 709bool Sema::SemaBuiltinFPClassification(CallExpr *TheCall, unsigned NumArgs) { 710 if (TheCall->getNumArgs() < NumArgs) 711 return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args) 712 << 0 << NumArgs << TheCall->getNumArgs()/*function call*/; 713 if (TheCall->getNumArgs() > NumArgs) 714 return Diag(TheCall->getArg(NumArgs)->getLocStart(), 715 diag::err_typecheck_call_too_many_args) 716 << 0 /*function call*/ << NumArgs << TheCall->getNumArgs() 717 << SourceRange(TheCall->getArg(NumArgs)->getLocStart(), 718 (*(TheCall->arg_end()-1))->getLocEnd()); 719 720 Expr *OrigArg = TheCall->getArg(NumArgs-1); 721 722 if (OrigArg->isTypeDependent()) 723 return false; 724 725 // This operation requires a non-_Complex floating-point number. 726 if (!OrigArg->getType()->isRealFloatingType()) 727 return Diag(OrigArg->getLocStart(), 728 diag::err_typecheck_call_invalid_unary_fp) 729 << OrigArg->getType() << OrigArg->getSourceRange(); 730 731 // If this is an implicit conversion from float -> double, remove it. 732 if (ImplicitCastExpr *Cast = dyn_cast<ImplicitCastExpr>(OrigArg)) { 733 Expr *CastArg = Cast->getSubExpr(); 734 if (CastArg->getType()->isSpecificBuiltinType(BuiltinType::Float)) { 735 assert(Cast->getType()->isSpecificBuiltinType(BuiltinType::Double) && 736 "promotion from float to double is the only expected cast here"); 737 Cast->setSubExpr(0); 738 TheCall->setArg(NumArgs-1, CastArg); 739 OrigArg = CastArg; 740 } 741 } 742 743 return false; 744} 745 746/// SemaBuiltinShuffleVector - Handle __builtin_shufflevector. 747// This is declared to take (...), so we have to check everything. 748Action::OwningExprResult Sema::SemaBuiltinShuffleVector(CallExpr *TheCall) { 749 if (TheCall->getNumArgs() < 2) 750 return ExprError(Diag(TheCall->getLocEnd(), 751 diag::err_typecheck_call_too_few_args_at_least) 752 << 0 /*function call*/ << 2 << TheCall->getNumArgs() 753 << TheCall->getSourceRange()); 754 755 // Determine which of the following types of shufflevector we're checking: 756 // 1) unary, vector mask: (lhs, mask) 757 // 2) binary, vector mask: (lhs, rhs, mask) 758 // 3) binary, scalar mask: (lhs, rhs, index, ..., index) 759 QualType resType = TheCall->getArg(0)->getType(); 760 unsigned numElements = 0; 761 762 if (!TheCall->getArg(0)->isTypeDependent() && 763 !TheCall->getArg(1)->isTypeDependent()) { 764 QualType LHSType = TheCall->getArg(0)->getType(); 765 QualType RHSType = TheCall->getArg(1)->getType(); 766 767 if (!LHSType->isVectorType() || !RHSType->isVectorType()) { 768 Diag(TheCall->getLocStart(), diag::err_shufflevector_non_vector) 769 << SourceRange(TheCall->getArg(0)->getLocStart(), 770 TheCall->getArg(1)->getLocEnd()); 771 return ExprError(); 772 } 773 774 numElements = LHSType->getAs<VectorType>()->getNumElements(); 775 unsigned numResElements = TheCall->getNumArgs() - 2; 776 777 // Check to see if we have a call with 2 vector arguments, the unary shuffle 778 // with mask. If so, verify that RHS is an integer vector type with the 779 // same number of elts as lhs. 780 if (TheCall->getNumArgs() == 2) { 781 if (!RHSType->hasIntegerRepresentation() || 782 RHSType->getAs<VectorType>()->getNumElements() != numElements) 783 Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector) 784 << SourceRange(TheCall->getArg(1)->getLocStart(), 785 TheCall->getArg(1)->getLocEnd()); 786 numResElements = numElements; 787 } 788 else if (!Context.hasSameUnqualifiedType(LHSType, RHSType)) { 789 Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector) 790 << SourceRange(TheCall->getArg(0)->getLocStart(), 791 TheCall->getArg(1)->getLocEnd()); 792 return ExprError(); 793 } else if (numElements != numResElements) { 794 QualType eltType = LHSType->getAs<VectorType>()->getElementType(); 795 resType = Context.getVectorType(eltType, numResElements, 796 VectorType::NotAltiVec); 797 } 798 } 799 800 for (unsigned i = 2; i < TheCall->getNumArgs(); i++) { 801 if (TheCall->getArg(i)->isTypeDependent() || 802 TheCall->getArg(i)->isValueDependent()) 803 continue; 804 805 llvm::APSInt Result(32); 806 if (!TheCall->getArg(i)->isIntegerConstantExpr(Result, Context)) 807 return ExprError(Diag(TheCall->getLocStart(), 808 diag::err_shufflevector_nonconstant_argument) 809 << TheCall->getArg(i)->getSourceRange()); 810 811 if (Result.getActiveBits() > 64 || Result.getZExtValue() >= numElements*2) 812 return ExprError(Diag(TheCall->getLocStart(), 813 diag::err_shufflevector_argument_too_large) 814 << TheCall->getArg(i)->getSourceRange()); 815 } 816 817 llvm::SmallVector<Expr*, 32> exprs; 818 819 for (unsigned i = 0, e = TheCall->getNumArgs(); i != e; i++) { 820 exprs.push_back(TheCall->getArg(i)); 821 TheCall->setArg(i, 0); 822 } 823 824 return Owned(new (Context) ShuffleVectorExpr(Context, exprs.begin(), 825 exprs.size(), resType, 826 TheCall->getCallee()->getLocStart(), 827 TheCall->getRParenLoc())); 828} 829 830/// SemaBuiltinPrefetch - Handle __builtin_prefetch. 831// This is declared to take (const void*, ...) and can take two 832// optional constant int args. 833bool Sema::SemaBuiltinPrefetch(CallExpr *TheCall) { 834 unsigned NumArgs = TheCall->getNumArgs(); 835 836 if (NumArgs > 3) 837 return Diag(TheCall->getLocEnd(), 838 diag::err_typecheck_call_too_many_args_at_most) 839 << 0 /*function call*/ << 3 << NumArgs 840 << TheCall->getSourceRange(); 841 842 // Argument 0 is checked for us and the remaining arguments must be 843 // constant integers. 844 for (unsigned i = 1; i != NumArgs; ++i) { 845 Expr *Arg = TheCall->getArg(i); 846 847 llvm::APSInt Result; 848 if (SemaBuiltinConstantArg(TheCall, i, Result)) 849 return true; 850 851 // FIXME: gcc issues a warning and rewrites these to 0. These 852 // seems especially odd for the third argument since the default 853 // is 3. 854 if (i == 1) { 855 if (Result.getLimitedValue() > 1) 856 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 857 << "0" << "1" << Arg->getSourceRange(); 858 } else { 859 if (Result.getLimitedValue() > 3) 860 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 861 << "0" << "3" << Arg->getSourceRange(); 862 } 863 } 864 865 return false; 866} 867 868/// SemaBuiltinConstantArg - Handle a check if argument ArgNum of CallExpr 869/// TheCall is a constant expression. 870bool Sema::SemaBuiltinConstantArg(CallExpr *TheCall, int ArgNum, 871 llvm::APSInt &Result) { 872 Expr *Arg = TheCall->getArg(ArgNum); 873 DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts()); 874 FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl()); 875 876 if (Arg->isTypeDependent() || Arg->isValueDependent()) return false; 877 878 if (!Arg->isIntegerConstantExpr(Result, Context)) 879 return Diag(TheCall->getLocStart(), diag::err_constant_integer_arg_type) 880 << FDecl->getDeclName() << Arg->getSourceRange(); 881 882 return false; 883} 884 885/// SemaBuiltinObjectSize - Handle __builtin_object_size(void *ptr, 886/// int type). This simply type checks that type is one of the defined 887/// constants (0-3). 888// For compatability check 0-3, llvm only handles 0 and 2. 889bool Sema::SemaBuiltinObjectSize(CallExpr *TheCall) { 890 llvm::APSInt Result; 891 892 // Check constant-ness first. 893 if (SemaBuiltinConstantArg(TheCall, 1, Result)) 894 return true; 895 896 Expr *Arg = TheCall->getArg(1); 897 if (Result.getSExtValue() < 0 || Result.getSExtValue() > 3) { 898 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 899 << "0" << "3" << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); 900 } 901 902 return false; 903} 904 905/// SemaBuiltinLongjmp - Handle __builtin_longjmp(void *env[5], int val). 906/// This checks that val is a constant 1. 907bool Sema::SemaBuiltinLongjmp(CallExpr *TheCall) { 908 Expr *Arg = TheCall->getArg(1); 909 llvm::APSInt Result; 910 911 // TODO: This is less than ideal. Overload this to take a value. 912 if (SemaBuiltinConstantArg(TheCall, 1, Result)) 913 return true; 914 915 if (Result != 1) 916 return Diag(TheCall->getLocStart(), diag::err_builtin_longjmp_invalid_val) 917 << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); 918 919 return false; 920} 921 922// Handle i > 1 ? "x" : "y", recursivelly 923bool Sema::SemaCheckStringLiteral(const Expr *E, const CallExpr *TheCall, 924 bool HasVAListArg, 925 unsigned format_idx, unsigned firstDataArg, 926 bool isPrintf) { 927 928 if (E->isTypeDependent() || E->isValueDependent()) 929 return false; 930 931 switch (E->getStmtClass()) { 932 case Stmt::ConditionalOperatorClass: { 933 const ConditionalOperator *C = cast<ConditionalOperator>(E); 934 return SemaCheckStringLiteral(C->getTrueExpr(), TheCall, HasVAListArg, 935 format_idx, firstDataArg, isPrintf) 936 && SemaCheckStringLiteral(C->getRHS(), TheCall, HasVAListArg, 937 format_idx, firstDataArg, isPrintf); 938 } 939 940 case Stmt::ImplicitCastExprClass: { 941 const ImplicitCastExpr *Expr = cast<ImplicitCastExpr>(E); 942 return SemaCheckStringLiteral(Expr->getSubExpr(), TheCall, HasVAListArg, 943 format_idx, firstDataArg, isPrintf); 944 } 945 946 case Stmt::ParenExprClass: { 947 const ParenExpr *Expr = cast<ParenExpr>(E); 948 return SemaCheckStringLiteral(Expr->getSubExpr(), TheCall, HasVAListArg, 949 format_idx, firstDataArg, isPrintf); 950 } 951 952 case Stmt::DeclRefExprClass: { 953 const DeclRefExpr *DR = cast<DeclRefExpr>(E); 954 955 // As an exception, do not flag errors for variables binding to 956 // const string literals. 957 if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) { 958 bool isConstant = false; 959 QualType T = DR->getType(); 960 961 if (const ArrayType *AT = Context.getAsArrayType(T)) { 962 isConstant = AT->getElementType().isConstant(Context); 963 } else if (const PointerType *PT = T->getAs<PointerType>()) { 964 isConstant = T.isConstant(Context) && 965 PT->getPointeeType().isConstant(Context); 966 } 967 968 if (isConstant) { 969 if (const Expr *Init = VD->getAnyInitializer()) 970 return SemaCheckStringLiteral(Init, TheCall, 971 HasVAListArg, format_idx, firstDataArg, 972 isPrintf); 973 } 974 975 // For vprintf* functions (i.e., HasVAListArg==true), we add a 976 // special check to see if the format string is a function parameter 977 // of the function calling the printf function. If the function 978 // has an attribute indicating it is a printf-like function, then we 979 // should suppress warnings concerning non-literals being used in a call 980 // to a vprintf function. For example: 981 // 982 // void 983 // logmessage(char const *fmt __attribute__ (format (printf, 1, 2)), ...){ 984 // va_list ap; 985 // va_start(ap, fmt); 986 // vprintf(fmt, ap); // Do NOT emit a warning about "fmt". 987 // ... 988 // 989 // 990 // FIXME: We don't have full attribute support yet, so just check to see 991 // if the argument is a DeclRefExpr that references a parameter. We'll 992 // add proper support for checking the attribute later. 993 if (HasVAListArg) 994 if (isa<ParmVarDecl>(VD)) 995 return true; 996 } 997 998 return false; 999 } 1000 1001 case Stmt::CallExprClass: { 1002 const CallExpr *CE = cast<CallExpr>(E); 1003 if (const ImplicitCastExpr *ICE 1004 = dyn_cast<ImplicitCastExpr>(CE->getCallee())) { 1005 if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(ICE->getSubExpr())) { 1006 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(DRE->getDecl())) { 1007 if (const FormatArgAttr *FA = FD->getAttr<FormatArgAttr>()) { 1008 unsigned ArgIndex = FA->getFormatIdx(); 1009 const Expr *Arg = CE->getArg(ArgIndex - 1); 1010 1011 return SemaCheckStringLiteral(Arg, TheCall, HasVAListArg, 1012 format_idx, firstDataArg, isPrintf); 1013 } 1014 } 1015 } 1016 } 1017 1018 return false; 1019 } 1020 case Stmt::ObjCStringLiteralClass: 1021 case Stmt::StringLiteralClass: { 1022 const StringLiteral *StrE = NULL; 1023 1024 if (const ObjCStringLiteral *ObjCFExpr = dyn_cast<ObjCStringLiteral>(E)) 1025 StrE = ObjCFExpr->getString(); 1026 else 1027 StrE = cast<StringLiteral>(E); 1028 1029 if (StrE) { 1030 CheckFormatString(StrE, E, TheCall, HasVAListArg, format_idx, 1031 firstDataArg, isPrintf); 1032 return true; 1033 } 1034 1035 return false; 1036 } 1037 1038 default: 1039 return false; 1040 } 1041} 1042 1043void 1044Sema::CheckNonNullArguments(const NonNullAttr *NonNull, 1045 const CallExpr *TheCall) { 1046 for (NonNullAttr::iterator i = NonNull->begin(), e = NonNull->end(); 1047 i != e; ++i) { 1048 const Expr *ArgExpr = TheCall->getArg(*i); 1049 if (ArgExpr->isNullPointerConstant(Context, 1050 Expr::NPC_ValueDependentIsNotNull)) 1051 Diag(TheCall->getCallee()->getLocStart(), diag::warn_null_arg) 1052 << ArgExpr->getSourceRange(); 1053 } 1054} 1055 1056/// CheckPrintfScanfArguments - Check calls to printf and scanf (and similar 1057/// functions) for correct use of format strings. 1058void 1059Sema::CheckPrintfScanfArguments(const CallExpr *TheCall, bool HasVAListArg, 1060 unsigned format_idx, unsigned firstDataArg, 1061 bool isPrintf) { 1062 1063 const Expr *Fn = TheCall->getCallee(); 1064 1065 // The way the format attribute works in GCC, the implicit this argument 1066 // of member functions is counted. However, it doesn't appear in our own 1067 // lists, so decrement format_idx in that case. 1068 if (isa<CXXMemberCallExpr>(TheCall)) { 1069 // Catch a format attribute mistakenly referring to the object argument. 1070 if (format_idx == 0) 1071 return; 1072 --format_idx; 1073 if(firstDataArg != 0) 1074 --firstDataArg; 1075 } 1076 1077 // CHECK: printf/scanf-like function is called with no format string. 1078 if (format_idx >= TheCall->getNumArgs()) { 1079 Diag(TheCall->getRParenLoc(), diag::warn_missing_format_string) 1080 << Fn->getSourceRange(); 1081 return; 1082 } 1083 1084 const Expr *OrigFormatExpr = TheCall->getArg(format_idx)->IgnoreParenCasts(); 1085 1086 // CHECK: format string is not a string literal. 1087 // 1088 // Dynamically generated format strings are difficult to 1089 // automatically vet at compile time. Requiring that format strings 1090 // are string literals: (1) permits the checking of format strings by 1091 // the compiler and thereby (2) can practically remove the source of 1092 // many format string exploits. 1093 1094 // Format string can be either ObjC string (e.g. @"%d") or 1095 // C string (e.g. "%d") 1096 // ObjC string uses the same format specifiers as C string, so we can use 1097 // the same format string checking logic for both ObjC and C strings. 1098 if (SemaCheckStringLiteral(OrigFormatExpr, TheCall, HasVAListArg, format_idx, 1099 firstDataArg, isPrintf)) 1100 return; // Literal format string found, check done! 1101 1102 // If there are no arguments specified, warn with -Wformat-security, otherwise 1103 // warn only with -Wformat-nonliteral. 1104 if (TheCall->getNumArgs() == format_idx+1) 1105 Diag(TheCall->getArg(format_idx)->getLocStart(), 1106 diag::warn_format_nonliteral_noargs) 1107 << OrigFormatExpr->getSourceRange(); 1108 else 1109 Diag(TheCall->getArg(format_idx)->getLocStart(), 1110 diag::warn_format_nonliteral) 1111 << OrigFormatExpr->getSourceRange(); 1112} 1113 1114namespace { 1115class CheckFormatHandler : public analyze_format_string::FormatStringHandler { 1116protected: 1117 Sema &S; 1118 const StringLiteral *FExpr; 1119 const Expr *OrigFormatExpr; 1120 const unsigned FirstDataArg; 1121 const unsigned NumDataArgs; 1122 const bool IsObjCLiteral; 1123 const char *Beg; // Start of format string. 1124 const bool HasVAListArg; 1125 const CallExpr *TheCall; 1126 unsigned FormatIdx; 1127 llvm::BitVector CoveredArgs; 1128 bool usesPositionalArgs; 1129 bool atFirstArg; 1130public: 1131 CheckFormatHandler(Sema &s, const StringLiteral *fexpr, 1132 const Expr *origFormatExpr, unsigned firstDataArg, 1133 unsigned numDataArgs, bool isObjCLiteral, 1134 const char *beg, bool hasVAListArg, 1135 const CallExpr *theCall, unsigned formatIdx) 1136 : S(s), FExpr(fexpr), OrigFormatExpr(origFormatExpr), 1137 FirstDataArg(firstDataArg), 1138 NumDataArgs(numDataArgs), 1139 IsObjCLiteral(isObjCLiteral), Beg(beg), 1140 HasVAListArg(hasVAListArg), 1141 TheCall(theCall), FormatIdx(formatIdx), 1142 usesPositionalArgs(false), atFirstArg(true) { 1143 CoveredArgs.resize(numDataArgs); 1144 CoveredArgs.reset(); 1145 } 1146 1147 void DoneProcessing(); 1148 1149 void HandleIncompleteSpecifier(const char *startSpecifier, 1150 unsigned specifierLen); 1151 1152 virtual void HandleInvalidPosition(const char *startSpecifier, 1153 unsigned specifierLen, 1154 analyze_format_string::PositionContext p); 1155 1156 virtual void HandleZeroPosition(const char *startPos, unsigned posLen); 1157 1158 void HandleNullChar(const char *nullCharacter); 1159 1160protected: 1161 bool HandleInvalidConversionSpecifier(unsigned argIndex, SourceLocation Loc, 1162 const char *startSpec, 1163 unsigned specifierLen, 1164 const char *csStart, unsigned csLen); 1165 1166 SourceRange getFormatStringRange(); 1167 CharSourceRange getSpecifierRange(const char *startSpecifier, 1168 unsigned specifierLen); 1169 SourceLocation getLocationOfByte(const char *x); 1170 1171 const Expr *getDataArg(unsigned i) const; 1172 1173 bool CheckNumArgs(const analyze_format_string::FormatSpecifier &FS, 1174 const analyze_format_string::ConversionSpecifier &CS, 1175 const char *startSpecifier, unsigned specifierLen, 1176 unsigned argIndex); 1177 1178 void CheckArgType(const analyze_format_string::FormatSpecifier &FS, 1179 const analyze_format_string::ConversionSpecifier &CS, 1180 const char *startSpecifier, unsigned specifierLen, 1181 unsigned argIndex); 1182}; 1183} 1184 1185SourceRange CheckFormatHandler::getFormatStringRange() { 1186 return OrigFormatExpr->getSourceRange(); 1187} 1188 1189CharSourceRange CheckFormatHandler:: 1190getSpecifierRange(const char *startSpecifier, unsigned specifierLen) { 1191 SourceLocation Start = getLocationOfByte(startSpecifier); 1192 SourceLocation End = getLocationOfByte(startSpecifier + specifierLen - 1); 1193 1194 // Advance the end SourceLocation by one due to half-open ranges. 1195 End = End.getFileLocWithOffset(1); 1196 1197 return CharSourceRange::getCharRange(Start, End); 1198} 1199 1200SourceLocation CheckFormatHandler::getLocationOfByte(const char *x) { 1201 return S.getLocationOfStringLiteralByte(FExpr, x - Beg); 1202} 1203 1204void CheckFormatHandler::HandleIncompleteSpecifier(const char *startSpecifier, 1205 unsigned specifierLen){ 1206 SourceLocation Loc = getLocationOfByte(startSpecifier); 1207 S.Diag(Loc, diag::warn_printf_incomplete_specifier) 1208 << getSpecifierRange(startSpecifier, specifierLen); 1209} 1210 1211void 1212CheckFormatHandler::HandleInvalidPosition(const char *startPos, unsigned posLen, 1213 analyze_format_string::PositionContext p) { 1214 SourceLocation Loc = getLocationOfByte(startPos); 1215 S.Diag(Loc, diag::warn_format_invalid_positional_specifier) 1216 << (unsigned) p << getSpecifierRange(startPos, posLen); 1217} 1218 1219void CheckFormatHandler::HandleZeroPosition(const char *startPos, 1220 unsigned posLen) { 1221 SourceLocation Loc = getLocationOfByte(startPos); 1222 S.Diag(Loc, diag::warn_format_zero_positional_specifier) 1223 << getSpecifierRange(startPos, posLen); 1224} 1225 1226void CheckFormatHandler::HandleNullChar(const char *nullCharacter) { 1227 // The presence of a null character is likely an error. 1228 S.Diag(getLocationOfByte(nullCharacter), 1229 diag::warn_printf_format_string_contains_null_char) 1230 << getFormatStringRange(); 1231} 1232 1233const Expr *CheckFormatHandler::getDataArg(unsigned i) const { 1234 return TheCall->getArg(FirstDataArg + i); 1235} 1236 1237void CheckFormatHandler::DoneProcessing() { 1238 // Does the number of data arguments exceed the number of 1239 // format conversions in the format string? 1240 if (!HasVAListArg) { 1241 // Find any arguments that weren't covered. 1242 CoveredArgs.flip(); 1243 signed notCoveredArg = CoveredArgs.find_first(); 1244 if (notCoveredArg >= 0) { 1245 assert((unsigned)notCoveredArg < NumDataArgs); 1246 S.Diag(getDataArg((unsigned) notCoveredArg)->getLocStart(), 1247 diag::warn_printf_data_arg_not_used) 1248 << getFormatStringRange(); 1249 } 1250 } 1251} 1252 1253bool 1254CheckFormatHandler::HandleInvalidConversionSpecifier(unsigned argIndex, 1255 SourceLocation Loc, 1256 const char *startSpec, 1257 unsigned specifierLen, 1258 const char *csStart, 1259 unsigned csLen) { 1260 1261 bool keepGoing = true; 1262 if (argIndex < NumDataArgs) { 1263 // Consider the argument coverered, even though the specifier doesn't 1264 // make sense. 1265 CoveredArgs.set(argIndex); 1266 } 1267 else { 1268 // If argIndex exceeds the number of data arguments we 1269 // don't issue a warning because that is just a cascade of warnings (and 1270 // they may have intended '%%' anyway). We don't want to continue processing 1271 // the format string after this point, however, as we will like just get 1272 // gibberish when trying to match arguments. 1273 keepGoing = false; 1274 } 1275 1276 S.Diag(Loc, diag::warn_format_invalid_conversion) 1277 << llvm::StringRef(csStart, csLen) 1278 << getSpecifierRange(startSpec, specifierLen); 1279 1280 return keepGoing; 1281} 1282 1283bool 1284CheckFormatHandler::CheckNumArgs( 1285 const analyze_format_string::FormatSpecifier &FS, 1286 const analyze_format_string::ConversionSpecifier &CS, 1287 const char *startSpecifier, unsigned specifierLen, unsigned argIndex) { 1288 1289 if (argIndex >= NumDataArgs) { 1290 if (FS.usesPositionalArg()) { 1291 S.Diag(getLocationOfByte(CS.getStart()), 1292 diag::warn_printf_positional_arg_exceeds_data_args) 1293 << (argIndex+1) << NumDataArgs 1294 << getSpecifierRange(startSpecifier, specifierLen); 1295 } 1296 else { 1297 S.Diag(getLocationOfByte(CS.getStart()), 1298 diag::warn_printf_insufficient_data_args) 1299 << getSpecifierRange(startSpecifier, specifierLen); 1300 } 1301 1302 return false; 1303 } 1304 return true; 1305} 1306 1307void CheckFormatHandler::CheckArgType( 1308 const analyze_format_string::FormatSpecifier &FS, 1309 const analyze_format_string::ConversionSpecifier &CS, 1310 const char *startSpecifier, unsigned specifierLen, unsigned argIndex) { 1311 1312 const Expr *Ex = getDataArg(argIndex); 1313 const analyze_format_string::ArgTypeResult &ATR = FS.getArgType(S.Context); 1314 1315 if (ATR.isValid() && !ATR.matchesType(S.Context, Ex->getType())) { 1316 // Check if we didn't match because of an implicit cast from a 'char' 1317 // or 'short' to an 'int'. This is done because scanf/printf are varargs 1318 // functions. 1319 if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Ex)) 1320 if (ICE->getType() == S.Context.IntTy) 1321 if (ATR.matchesType(S.Context, ICE->getSubExpr()->getType())) 1322 return; 1323 1324 if (const analyze_printf::PrintfSpecifier *PFS = 1325 dyn_cast<analyze_printf::PrintfSpecifier>(&FS)) { 1326 // We may be able to offer a FixItHint if it is a supported type. 1327 analyze_printf::PrintfSpecifier fixedFS(*PFS); 1328 if (fixedFS.fixType(Ex->getType())) { 1329 // Get the fix string from the fixed format specifier 1330 llvm::SmallString<128> buf; 1331 llvm::raw_svector_ostream os(buf); 1332 fixedFS.toString(os); 1333 1334 S.Diag(getLocationOfByte(CS.getStart()), 1335 diag::warn_printf_conversion_argument_type_mismatch) 1336 << ATR.getRepresentativeType(S.Context) << Ex->getType() 1337 << getSpecifierRange(startSpecifier, specifierLen) 1338 << Ex->getSourceRange() 1339 << FixItHint::CreateReplacement( 1340 getSpecifierRange(startSpecifier, specifierLen), os.str()); 1341 } 1342 else { 1343 S.Diag(getLocationOfByte(CS.getStart()), 1344 diag::warn_printf_conversion_argument_type_mismatch) 1345 << ATR.getRepresentativeType(S.Context) << Ex->getType() 1346 << getSpecifierRange(startSpecifier, specifierLen) 1347 << Ex->getSourceRange(); 1348 } 1349 } 1350 } 1351} 1352 1353//===--- CHECK: Printf format string checking ------------------------------===// 1354 1355namespace { 1356class CheckPrintfHandler : public CheckFormatHandler { 1357public: 1358 CheckPrintfHandler(Sema &s, const StringLiteral *fexpr, 1359 const Expr *origFormatExpr, unsigned firstDataArg, 1360 unsigned numDataArgs, bool isObjCLiteral, 1361 const char *beg, bool hasVAListArg, 1362 const CallExpr *theCall, unsigned formatIdx) 1363 : CheckFormatHandler(s, fexpr, origFormatExpr, firstDataArg, 1364 numDataArgs, isObjCLiteral, beg, hasVAListArg, 1365 theCall, formatIdx) {} 1366 1367 1368 bool HandleInvalidPrintfConversionSpecifier( 1369 const analyze_printf::PrintfSpecifier &FS, 1370 const char *startSpecifier, 1371 unsigned specifierLen); 1372 1373 bool HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier &FS, 1374 const char *startSpecifier, 1375 unsigned specifierLen); 1376 1377 bool HandleAmount(const analyze_format_string::OptionalAmount &Amt, unsigned k, 1378 const char *startSpecifier, unsigned specifierLen); 1379 void HandleInvalidAmount(const analyze_printf::PrintfSpecifier &FS, 1380 const analyze_printf::OptionalAmount &Amt, 1381 unsigned type, 1382 const char *startSpecifier, unsigned specifierLen); 1383 void HandleFlag(const analyze_printf::PrintfSpecifier &FS, 1384 const analyze_printf::OptionalFlag &flag, 1385 const char *startSpecifier, unsigned specifierLen); 1386 void HandleIgnoredFlag(const analyze_printf::PrintfSpecifier &FS, 1387 const analyze_printf::OptionalFlag &ignoredFlag, 1388 const analyze_printf::OptionalFlag &flag, 1389 const char *startSpecifier, unsigned specifierLen); 1390}; 1391} 1392 1393bool CheckPrintfHandler::HandleInvalidPrintfConversionSpecifier( 1394 const analyze_printf::PrintfSpecifier &FS, 1395 const char *startSpecifier, 1396 unsigned specifierLen) { 1397 const analyze_printf::PrintfConversionSpecifier &CS = 1398 FS.getConversionSpecifier(); 1399 1400 return HandleInvalidConversionSpecifier(FS.getArgIndex(), 1401 getLocationOfByte(CS.getStart()), 1402 startSpecifier, specifierLen, 1403 CS.getStart(), CS.getLength()); 1404} 1405 1406bool CheckPrintfHandler::HandleAmount( 1407 const analyze_format_string::OptionalAmount &Amt, 1408 unsigned k, const char *startSpecifier, 1409 unsigned specifierLen) { 1410 1411 if (Amt.hasDataArgument()) { 1412 if (!HasVAListArg) { 1413 unsigned argIndex = Amt.getArgIndex(); 1414 if (argIndex >= NumDataArgs) { 1415 S.Diag(getLocationOfByte(Amt.getStart()), 1416 diag::warn_printf_asterisk_missing_arg) 1417 << k << getSpecifierRange(startSpecifier, specifierLen); 1418 // Don't do any more checking. We will just emit 1419 // spurious errors. 1420 return false; 1421 } 1422 1423 // Type check the data argument. It should be an 'int'. 1424 // Although not in conformance with C99, we also allow the argument to be 1425 // an 'unsigned int' as that is a reasonably safe case. GCC also 1426 // doesn't emit a warning for that case. 1427 CoveredArgs.set(argIndex); 1428 const Expr *Arg = getDataArg(argIndex); 1429 QualType T = Arg->getType(); 1430 1431 const analyze_printf::ArgTypeResult &ATR = Amt.getArgType(S.Context); 1432 assert(ATR.isValid()); 1433 1434 if (!ATR.matchesType(S.Context, T)) { 1435 S.Diag(getLocationOfByte(Amt.getStart()), 1436 diag::warn_printf_asterisk_wrong_type) 1437 << k 1438 << ATR.getRepresentativeType(S.Context) << T 1439 << getSpecifierRange(startSpecifier, specifierLen) 1440 << Arg->getSourceRange(); 1441 // Don't do any more checking. We will just emit 1442 // spurious errors. 1443 return false; 1444 } 1445 } 1446 } 1447 return true; 1448} 1449 1450void CheckPrintfHandler::HandleInvalidAmount( 1451 const analyze_printf::PrintfSpecifier &FS, 1452 const analyze_printf::OptionalAmount &Amt, 1453 unsigned type, 1454 const char *startSpecifier, 1455 unsigned specifierLen) { 1456 const analyze_printf::PrintfConversionSpecifier &CS = 1457 FS.getConversionSpecifier(); 1458 switch (Amt.getHowSpecified()) { 1459 case analyze_printf::OptionalAmount::Constant: 1460 S.Diag(getLocationOfByte(Amt.getStart()), 1461 diag::warn_printf_nonsensical_optional_amount) 1462 << type 1463 << CS.toString() 1464 << getSpecifierRange(startSpecifier, specifierLen) 1465 << FixItHint::CreateRemoval(getSpecifierRange(Amt.getStart(), 1466 Amt.getConstantLength())); 1467 break; 1468 1469 default: 1470 S.Diag(getLocationOfByte(Amt.getStart()), 1471 diag::warn_printf_nonsensical_optional_amount) 1472 << type 1473 << CS.toString() 1474 << getSpecifierRange(startSpecifier, specifierLen); 1475 break; 1476 } 1477} 1478 1479void CheckPrintfHandler::HandleFlag(const analyze_printf::PrintfSpecifier &FS, 1480 const analyze_printf::OptionalFlag &flag, 1481 const char *startSpecifier, 1482 unsigned specifierLen) { 1483 // Warn about pointless flag with a fixit removal. 1484 const analyze_printf::PrintfConversionSpecifier &CS = 1485 FS.getConversionSpecifier(); 1486 S.Diag(getLocationOfByte(flag.getPosition()), 1487 diag::warn_printf_nonsensical_flag) 1488 << flag.toString() << CS.toString() 1489 << getSpecifierRange(startSpecifier, specifierLen) 1490 << FixItHint::CreateRemoval(getSpecifierRange(flag.getPosition(), 1)); 1491} 1492 1493void CheckPrintfHandler::HandleIgnoredFlag( 1494 const analyze_printf::PrintfSpecifier &FS, 1495 const analyze_printf::OptionalFlag &ignoredFlag, 1496 const analyze_printf::OptionalFlag &flag, 1497 const char *startSpecifier, 1498 unsigned specifierLen) { 1499 // Warn about ignored flag with a fixit removal. 1500 S.Diag(getLocationOfByte(ignoredFlag.getPosition()), 1501 diag::warn_printf_ignored_flag) 1502 << ignoredFlag.toString() << flag.toString() 1503 << getSpecifierRange(startSpecifier, specifierLen) 1504 << FixItHint::CreateRemoval(getSpecifierRange( 1505 ignoredFlag.getPosition(), 1)); 1506} 1507 1508bool 1509CheckPrintfHandler::HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier 1510 &FS, 1511 const char *startSpecifier, 1512 unsigned specifierLen) { 1513 1514 using namespace analyze_format_string; 1515 using namespace analyze_printf; 1516 const PrintfConversionSpecifier &CS = FS.getConversionSpecifier(); 1517 1518 if (FS.consumesDataArgument()) { 1519 if (atFirstArg) { 1520 atFirstArg = false; 1521 usesPositionalArgs = FS.usesPositionalArg(); 1522 } 1523 else if (usesPositionalArgs != FS.usesPositionalArg()) { 1524 // Cannot mix-and-match positional and non-positional arguments. 1525 S.Diag(getLocationOfByte(CS.getStart()), 1526 diag::warn_format_mix_positional_nonpositional_args) 1527 << getSpecifierRange(startSpecifier, specifierLen); 1528 return false; 1529 } 1530 } 1531 1532 // First check if the field width, precision, and conversion specifier 1533 // have matching data arguments. 1534 if (!HandleAmount(FS.getFieldWidth(), /* field width */ 0, 1535 startSpecifier, specifierLen)) { 1536 return false; 1537 } 1538 1539 if (!HandleAmount(FS.getPrecision(), /* precision */ 1, 1540 startSpecifier, specifierLen)) { 1541 return false; 1542 } 1543 1544 if (!CS.consumesDataArgument()) { 1545 // FIXME: Technically specifying a precision or field width here 1546 // makes no sense. Worth issuing a warning at some point. 1547 return true; 1548 } 1549 1550 // Consume the argument. 1551 unsigned argIndex = FS.getArgIndex(); 1552 if (argIndex < NumDataArgs) { 1553 // The check to see if the argIndex is valid will come later. 1554 // We set the bit here because we may exit early from this 1555 // function if we encounter some other error. 1556 CoveredArgs.set(argIndex); 1557 } 1558 1559 // Check for using an Objective-C specific conversion specifier 1560 // in a non-ObjC literal. 1561 if (!IsObjCLiteral && CS.isObjCArg()) { 1562 return HandleInvalidPrintfConversionSpecifier(FS, startSpecifier, 1563 specifierLen); 1564 } 1565 1566 // Check for invalid use of field width 1567 if (!FS.hasValidFieldWidth()) { 1568 HandleInvalidAmount(FS, FS.getFieldWidth(), /* field width */ 0, 1569 startSpecifier, specifierLen); 1570 } 1571 1572 // Check for invalid use of precision 1573 if (!FS.hasValidPrecision()) { 1574 HandleInvalidAmount(FS, FS.getPrecision(), /* precision */ 1, 1575 startSpecifier, specifierLen); 1576 } 1577 1578 // Check each flag does not conflict with any other component. 1579 if (!FS.hasValidLeadingZeros()) 1580 HandleFlag(FS, FS.hasLeadingZeros(), startSpecifier, specifierLen); 1581 if (!FS.hasValidPlusPrefix()) 1582 HandleFlag(FS, FS.hasPlusPrefix(), startSpecifier, specifierLen); 1583 if (!FS.hasValidSpacePrefix()) 1584 HandleFlag(FS, FS.hasSpacePrefix(), startSpecifier, specifierLen); 1585 if (!FS.hasValidAlternativeForm()) 1586 HandleFlag(FS, FS.hasAlternativeForm(), startSpecifier, specifierLen); 1587 if (!FS.hasValidLeftJustified()) 1588 HandleFlag(FS, FS.isLeftJustified(), startSpecifier, specifierLen); 1589 1590 // Check that flags are not ignored by another flag 1591 if (FS.hasSpacePrefix() && FS.hasPlusPrefix()) // ' ' ignored by '+' 1592 HandleIgnoredFlag(FS, FS.hasSpacePrefix(), FS.hasPlusPrefix(), 1593 startSpecifier, specifierLen); 1594 if (FS.hasLeadingZeros() && FS.isLeftJustified()) // '0' ignored by '-' 1595 HandleIgnoredFlag(FS, FS.hasLeadingZeros(), FS.isLeftJustified(), 1596 startSpecifier, specifierLen); 1597 1598 // Check the length modifier is valid with the given conversion specifier. 1599 const LengthModifier &LM = FS.getLengthModifier(); 1600 if (!FS.hasValidLengthModifier()) 1601 S.Diag(getLocationOfByte(LM.getStart()), 1602 diag::warn_format_nonsensical_length) 1603 << LM.toString() << CS.toString() 1604 << getSpecifierRange(startSpecifier, specifierLen) 1605 << FixItHint::CreateRemoval(getSpecifierRange(LM.getStart(), 1606 LM.getLength())); 1607 1608 // Are we using '%n'? 1609 if (CS.getKind() == ConversionSpecifier::nArg) { 1610 // Issue a warning about this being a possible security issue. 1611 S.Diag(getLocationOfByte(CS.getStart()), diag::warn_printf_write_back) 1612 << getSpecifierRange(startSpecifier, specifierLen); 1613 // Continue checking the other format specifiers. 1614 return true; 1615 } 1616 1617 // The remaining checks depend on the data arguments. 1618 if (HasVAListArg) 1619 return true; 1620 1621 if (!CheckNumArgs(FS, CS, startSpecifier, specifierLen, argIndex)) 1622 return false; 1623 1624 CheckArgType(FS, CS, startSpecifier, specifierLen, argIndex); 1625 1626 return true; 1627} 1628 1629//===--- CHECK: Scanf format string checking ------------------------------===// 1630 1631namespace { 1632class CheckScanfHandler : public CheckFormatHandler { 1633public: 1634 CheckScanfHandler(Sema &s, const StringLiteral *fexpr, 1635 const Expr *origFormatExpr, unsigned firstDataArg, 1636 unsigned numDataArgs, bool isObjCLiteral, 1637 const char *beg, bool hasVAListArg, 1638 const CallExpr *theCall, unsigned formatIdx) 1639 : CheckFormatHandler(s, fexpr, origFormatExpr, firstDataArg, 1640 numDataArgs, isObjCLiteral, beg, hasVAListArg, 1641 theCall, formatIdx) {} 1642 1643 bool HandleScanfSpecifier(const analyze_scanf::ScanfSpecifier &FS, 1644 const char *startSpecifier, 1645 unsigned specifierLen); 1646 1647 bool HandleInvalidScanfConversionSpecifier( 1648 const analyze_scanf::ScanfSpecifier &FS, 1649 const char *startSpecifier, 1650 unsigned specifierLen); 1651 1652 void HandleIncompleteScanList(const char *start, const char *end); 1653}; 1654} 1655 1656void CheckScanfHandler::HandleIncompleteScanList(const char *start, 1657 const char *end) { 1658 S.Diag(getLocationOfByte(end), diag::warn_scanf_scanlist_incomplete) 1659 << getSpecifierRange(start, end - start); 1660} 1661 1662bool CheckScanfHandler::HandleInvalidScanfConversionSpecifier( 1663 const analyze_scanf::ScanfSpecifier &FS, 1664 const char *startSpecifier, 1665 unsigned specifierLen) { 1666 1667 const analyze_scanf::ScanfConversionSpecifier &CS = 1668 FS.getConversionSpecifier(); 1669 1670 return HandleInvalidConversionSpecifier(FS.getArgIndex(), 1671 getLocationOfByte(CS.getStart()), 1672 startSpecifier, specifierLen, 1673 CS.getStart(), CS.getLength()); 1674} 1675 1676bool CheckScanfHandler::HandleScanfSpecifier( 1677 const analyze_scanf::ScanfSpecifier &FS, 1678 const char *startSpecifier, 1679 unsigned specifierLen) { 1680 1681 using namespace analyze_scanf; 1682 using namespace analyze_format_string; 1683 1684 const ScanfConversionSpecifier &CS = FS.getConversionSpecifier(); 1685 1686 // Handle case where '%' and '*' don't consume an argument. These shouldn't 1687 // be used to decide if we are using positional arguments consistently. 1688 if (FS.consumesDataArgument()) { 1689 if (atFirstArg) { 1690 atFirstArg = false; 1691 usesPositionalArgs = FS.usesPositionalArg(); 1692 } 1693 else if (usesPositionalArgs != FS.usesPositionalArg()) { 1694 // Cannot mix-and-match positional and non-positional arguments. 1695 S.Diag(getLocationOfByte(CS.getStart()), 1696 diag::warn_format_mix_positional_nonpositional_args) 1697 << getSpecifierRange(startSpecifier, specifierLen); 1698 return false; 1699 } 1700 } 1701 1702 // Check if the field with is non-zero. 1703 const OptionalAmount &Amt = FS.getFieldWidth(); 1704 if (Amt.getHowSpecified() == OptionalAmount::Constant) { 1705 if (Amt.getConstantAmount() == 0) { 1706 const CharSourceRange &R = getSpecifierRange(Amt.getStart(), 1707 Amt.getConstantLength()); 1708 S.Diag(getLocationOfByte(Amt.getStart()), 1709 diag::warn_scanf_nonzero_width) 1710 << R << FixItHint::CreateRemoval(R); 1711 } 1712 } 1713 1714 if (!FS.consumesDataArgument()) { 1715 // FIXME: Technically specifying a precision or field width here 1716 // makes no sense. Worth issuing a warning at some point. 1717 return true; 1718 } 1719 1720 // Consume the argument. 1721 unsigned argIndex = FS.getArgIndex(); 1722 if (argIndex < NumDataArgs) { 1723 // The check to see if the argIndex is valid will come later. 1724 // We set the bit here because we may exit early from this 1725 // function if we encounter some other error. 1726 CoveredArgs.set(argIndex); 1727 } 1728 1729 // Check the length modifier is valid with the given conversion specifier. 1730 const LengthModifier &LM = FS.getLengthModifier(); 1731 if (!FS.hasValidLengthModifier()) { 1732 S.Diag(getLocationOfByte(LM.getStart()), 1733 diag::warn_format_nonsensical_length) 1734 << LM.toString() << CS.toString() 1735 << getSpecifierRange(startSpecifier, specifierLen) 1736 << FixItHint::CreateRemoval(getSpecifierRange(LM.getStart(), 1737 LM.getLength())); 1738 } 1739 1740 // The remaining checks depend on the data arguments. 1741 if (HasVAListArg) 1742 return true; 1743 1744 if (!CheckNumArgs(FS, CS, startSpecifier, specifierLen, argIndex)) 1745 return false; 1746 1747 // FIXME: Check that the argument type matches the format specifier. 1748 1749 return true; 1750} 1751 1752void Sema::CheckFormatString(const StringLiteral *FExpr, 1753 const Expr *OrigFormatExpr, 1754 const CallExpr *TheCall, bool HasVAListArg, 1755 unsigned format_idx, unsigned firstDataArg, 1756 bool isPrintf) { 1757 1758 // CHECK: is the format string a wide literal? 1759 if (FExpr->isWide()) { 1760 Diag(FExpr->getLocStart(), 1761 diag::warn_format_string_is_wide_literal) 1762 << OrigFormatExpr->getSourceRange(); 1763 return; 1764 } 1765 1766 // Str - The format string. NOTE: this is NOT null-terminated! 1767 const char *Str = FExpr->getStrData(); 1768 1769 // CHECK: empty format string? 1770 unsigned StrLen = FExpr->getByteLength(); 1771 1772 if (StrLen == 0) { 1773 Diag(FExpr->getLocStart(), diag::warn_empty_format_string) 1774 << OrigFormatExpr->getSourceRange(); 1775 return; 1776 } 1777 1778 if (isPrintf) { 1779 CheckPrintfHandler H(*this, FExpr, OrigFormatExpr, firstDataArg, 1780 TheCall->getNumArgs() - firstDataArg, 1781 isa<ObjCStringLiteral>(OrigFormatExpr), Str, 1782 HasVAListArg, TheCall, format_idx); 1783 1784 if (!analyze_format_string::ParsePrintfString(H, Str, Str + StrLen)) 1785 H.DoneProcessing(); 1786 } 1787 else { 1788 CheckScanfHandler H(*this, FExpr, OrigFormatExpr, firstDataArg, 1789 TheCall->getNumArgs() - firstDataArg, 1790 isa<ObjCStringLiteral>(OrigFormatExpr), Str, 1791 HasVAListArg, TheCall, format_idx); 1792 1793 if (!analyze_format_string::ParseScanfString(H, Str, Str + StrLen)) 1794 H.DoneProcessing(); 1795 } 1796} 1797 1798//===--- CHECK: Return Address of Stack Variable --------------------------===// 1799 1800static DeclRefExpr* EvalVal(Expr *E); 1801static DeclRefExpr* EvalAddr(Expr* E); 1802 1803/// CheckReturnStackAddr - Check if a return statement returns the address 1804/// of a stack variable. 1805void 1806Sema::CheckReturnStackAddr(Expr *RetValExp, QualType lhsType, 1807 SourceLocation ReturnLoc) { 1808 1809 // Perform checking for returned stack addresses. 1810 if (lhsType->isPointerType() || lhsType->isBlockPointerType()) { 1811 if (DeclRefExpr *DR = EvalAddr(RetValExp)) 1812 Diag(DR->getLocStart(), diag::warn_ret_stack_addr) 1813 << DR->getDecl()->getDeclName() << RetValExp->getSourceRange(); 1814 1815 // Skip over implicit cast expressions when checking for block expressions. 1816 RetValExp = RetValExp->IgnoreParenCasts(); 1817 1818 if (BlockExpr *C = dyn_cast<BlockExpr>(RetValExp)) 1819 if (C->hasBlockDeclRefExprs()) 1820 Diag(C->getLocStart(), diag::err_ret_local_block) 1821 << C->getSourceRange(); 1822 1823 if (AddrLabelExpr *ALE = dyn_cast<AddrLabelExpr>(RetValExp)) 1824 Diag(ALE->getLocStart(), diag::warn_ret_addr_label) 1825 << ALE->getSourceRange(); 1826 1827 } else if (lhsType->isReferenceType()) { 1828 // Perform checking for stack values returned by reference. 1829 // Check for a reference to the stack 1830 if (DeclRefExpr *DR = EvalVal(RetValExp)) 1831 Diag(DR->getLocStart(), diag::warn_ret_stack_ref) 1832 << DR->getDecl()->getDeclName() << RetValExp->getSourceRange(); 1833 } 1834} 1835 1836/// EvalAddr - EvalAddr and EvalVal are mutually recursive functions that 1837/// check if the expression in a return statement evaluates to an address 1838/// to a location on the stack. The recursion is used to traverse the 1839/// AST of the return expression, with recursion backtracking when we 1840/// encounter a subexpression that (1) clearly does not lead to the address 1841/// of a stack variable or (2) is something we cannot determine leads to 1842/// the address of a stack variable based on such local checking. 1843/// 1844/// EvalAddr processes expressions that are pointers that are used as 1845/// references (and not L-values). EvalVal handles all other values. 1846/// At the base case of the recursion is a check for a DeclRefExpr* in 1847/// the refers to a stack variable. 1848/// 1849/// This implementation handles: 1850/// 1851/// * pointer-to-pointer casts 1852/// * implicit conversions from array references to pointers 1853/// * taking the address of fields 1854/// * arbitrary interplay between "&" and "*" operators 1855/// * pointer arithmetic from an address of a stack variable 1856/// * taking the address of an array element where the array is on the stack 1857static DeclRefExpr* EvalAddr(Expr *E) { 1858 // We should only be called for evaluating pointer expressions. 1859 assert((E->getType()->isAnyPointerType() || 1860 E->getType()->isBlockPointerType() || 1861 E->getType()->isObjCQualifiedIdType()) && 1862 "EvalAddr only works on pointers"); 1863 1864 // Our "symbolic interpreter" is just a dispatch off the currently 1865 // viewed AST node. We then recursively traverse the AST by calling 1866 // EvalAddr and EvalVal appropriately. 1867 switch (E->getStmtClass()) { 1868 case Stmt::ParenExprClass: 1869 // Ignore parentheses. 1870 return EvalAddr(cast<ParenExpr>(E)->getSubExpr()); 1871 1872 case Stmt::UnaryOperatorClass: { 1873 // The only unary operator that make sense to handle here 1874 // is AddrOf. All others don't make sense as pointers. 1875 UnaryOperator *U = cast<UnaryOperator>(E); 1876 1877 if (U->getOpcode() == UnaryOperator::AddrOf) 1878 return EvalVal(U->getSubExpr()); 1879 else 1880 return NULL; 1881 } 1882 1883 case Stmt::BinaryOperatorClass: { 1884 // Handle pointer arithmetic. All other binary operators are not valid 1885 // in this context. 1886 BinaryOperator *B = cast<BinaryOperator>(E); 1887 BinaryOperator::Opcode op = B->getOpcode(); 1888 1889 if (op != BinaryOperator::Add && op != BinaryOperator::Sub) 1890 return NULL; 1891 1892 Expr *Base = B->getLHS(); 1893 1894 // Determine which argument is the real pointer base. It could be 1895 // the RHS argument instead of the LHS. 1896 if (!Base->getType()->isPointerType()) Base = B->getRHS(); 1897 1898 assert (Base->getType()->isPointerType()); 1899 return EvalAddr(Base); 1900 } 1901 1902 // For conditional operators we need to see if either the LHS or RHS are 1903 // valid DeclRefExpr*s. If one of them is valid, we return it. 1904 case Stmt::ConditionalOperatorClass: { 1905 ConditionalOperator *C = cast<ConditionalOperator>(E); 1906 1907 // Handle the GNU extension for missing LHS. 1908 if (Expr *lhsExpr = C->getLHS()) 1909 if (DeclRefExpr* LHS = EvalAddr(lhsExpr)) 1910 return LHS; 1911 1912 return EvalAddr(C->getRHS()); 1913 } 1914 1915 // For casts, we need to handle conversions from arrays to 1916 // pointer values, and pointer-to-pointer conversions. 1917 case Stmt::ImplicitCastExprClass: 1918 case Stmt::CStyleCastExprClass: 1919 case Stmt::CXXFunctionalCastExprClass: { 1920 Expr* SubExpr = cast<CastExpr>(E)->getSubExpr(); 1921 QualType T = SubExpr->getType(); 1922 1923 if (SubExpr->getType()->isPointerType() || 1924 SubExpr->getType()->isBlockPointerType() || 1925 SubExpr->getType()->isObjCQualifiedIdType()) 1926 return EvalAddr(SubExpr); 1927 else if (T->isArrayType()) 1928 return EvalVal(SubExpr); 1929 else 1930 return 0; 1931 } 1932 1933 // C++ casts. For dynamic casts, static casts, and const casts, we 1934 // are always converting from a pointer-to-pointer, so we just blow 1935 // through the cast. In the case the dynamic cast doesn't fail (and 1936 // return NULL), we take the conservative route and report cases 1937 // where we return the address of a stack variable. For Reinterpre 1938 // FIXME: The comment about is wrong; we're not always converting 1939 // from pointer to pointer. I'm guessing that this code should also 1940 // handle references to objects. 1941 case Stmt::CXXStaticCastExprClass: 1942 case Stmt::CXXDynamicCastExprClass: 1943 case Stmt::CXXConstCastExprClass: 1944 case Stmt::CXXReinterpretCastExprClass: { 1945 Expr *S = cast<CXXNamedCastExpr>(E)->getSubExpr(); 1946 if (S->getType()->isPointerType() || S->getType()->isBlockPointerType()) 1947 return EvalAddr(S); 1948 else 1949 return NULL; 1950 } 1951 1952 // Everything else: we simply don't reason about them. 1953 default: 1954 return NULL; 1955 } 1956} 1957 1958 1959/// EvalVal - This function is complements EvalAddr in the mutual recursion. 1960/// See the comments for EvalAddr for more details. 1961static DeclRefExpr* EvalVal(Expr *E) { 1962 1963 // We should only be called for evaluating non-pointer expressions, or 1964 // expressions with a pointer type that are not used as references but instead 1965 // are l-values (e.g., DeclRefExpr with a pointer type). 1966 1967 // Our "symbolic interpreter" is just a dispatch off the currently 1968 // viewed AST node. We then recursively traverse the AST by calling 1969 // EvalAddr and EvalVal appropriately. 1970 switch (E->getStmtClass()) { 1971 case Stmt::DeclRefExprClass: { 1972 // DeclRefExpr: the base case. When we hit a DeclRefExpr we are looking 1973 // at code that refers to a variable's name. We check if it has local 1974 // storage within the function, and if so, return the expression. 1975 DeclRefExpr *DR = cast<DeclRefExpr>(E); 1976 1977 if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl())) 1978 if (V->hasLocalStorage() && !V->getType()->isReferenceType()) return DR; 1979 1980 return NULL; 1981 } 1982 1983 case Stmt::ParenExprClass: 1984 // Ignore parentheses. 1985 return EvalVal(cast<ParenExpr>(E)->getSubExpr()); 1986 1987 case Stmt::UnaryOperatorClass: { 1988 // The only unary operator that make sense to handle here 1989 // is Deref. All others don't resolve to a "name." This includes 1990 // handling all sorts of rvalues passed to a unary operator. 1991 UnaryOperator *U = cast<UnaryOperator>(E); 1992 1993 if (U->getOpcode() == UnaryOperator::Deref) 1994 return EvalAddr(U->getSubExpr()); 1995 1996 return NULL; 1997 } 1998 1999 case Stmt::ArraySubscriptExprClass: { 2000 // Array subscripts are potential references to data on the stack. We 2001 // retrieve the DeclRefExpr* for the array variable if it indeed 2002 // has local storage. 2003 return EvalAddr(cast<ArraySubscriptExpr>(E)->getBase()); 2004 } 2005 2006 case Stmt::ConditionalOperatorClass: { 2007 // For conditional operators we need to see if either the LHS or RHS are 2008 // non-NULL DeclRefExpr's. If one is non-NULL, we return it. 2009 ConditionalOperator *C = cast<ConditionalOperator>(E); 2010 2011 // Handle the GNU extension for missing LHS. 2012 if (Expr *lhsExpr = C->getLHS()) 2013 if (DeclRefExpr *LHS = EvalVal(lhsExpr)) 2014 return LHS; 2015 2016 return EvalVal(C->getRHS()); 2017 } 2018 2019 // Accesses to members are potential references to data on the stack. 2020 case Stmt::MemberExprClass: { 2021 MemberExpr *M = cast<MemberExpr>(E); 2022 2023 // Check for indirect access. We only want direct field accesses. 2024 if (!M->isArrow()) 2025 return EvalVal(M->getBase()); 2026 else 2027 return NULL; 2028 } 2029 2030 // Everything else: we simply don't reason about them. 2031 default: 2032 return NULL; 2033 } 2034} 2035 2036//===--- CHECK: Floating-Point comparisons (-Wfloat-equal) ---------------===// 2037 2038/// Check for comparisons of floating point operands using != and ==. 2039/// Issue a warning if these are no self-comparisons, as they are not likely 2040/// to do what the programmer intended. 2041void Sema::CheckFloatComparison(SourceLocation loc, Expr* lex, Expr *rex) { 2042 bool EmitWarning = true; 2043 2044 Expr* LeftExprSansParen = lex->IgnoreParens(); 2045 Expr* RightExprSansParen = rex->IgnoreParens(); 2046 2047 // Special case: check for x == x (which is OK). 2048 // Do not emit warnings for such cases. 2049 if (DeclRefExpr* DRL = dyn_cast<DeclRefExpr>(LeftExprSansParen)) 2050 if (DeclRefExpr* DRR = dyn_cast<DeclRefExpr>(RightExprSansParen)) 2051 if (DRL->getDecl() == DRR->getDecl()) 2052 EmitWarning = false; 2053 2054 2055 // Special case: check for comparisons against literals that can be exactly 2056 // represented by APFloat. In such cases, do not emit a warning. This 2057 // is a heuristic: often comparison against such literals are used to 2058 // detect if a value in a variable has not changed. This clearly can 2059 // lead to false negatives. 2060 if (EmitWarning) { 2061 if (FloatingLiteral* FLL = dyn_cast<FloatingLiteral>(LeftExprSansParen)) { 2062 if (FLL->isExact()) 2063 EmitWarning = false; 2064 } else 2065 if (FloatingLiteral* FLR = dyn_cast<FloatingLiteral>(RightExprSansParen)){ 2066 if (FLR->isExact()) 2067 EmitWarning = false; 2068 } 2069 } 2070 2071 // Check for comparisons with builtin types. 2072 if (EmitWarning) 2073 if (CallExpr* CL = dyn_cast<CallExpr>(LeftExprSansParen)) 2074 if (CL->isBuiltinCall(Context)) 2075 EmitWarning = false; 2076 2077 if (EmitWarning) 2078 if (CallExpr* CR = dyn_cast<CallExpr>(RightExprSansParen)) 2079 if (CR->isBuiltinCall(Context)) 2080 EmitWarning = false; 2081 2082 // Emit the diagnostic. 2083 if (EmitWarning) 2084 Diag(loc, diag::warn_floatingpoint_eq) 2085 << lex->getSourceRange() << rex->getSourceRange(); 2086} 2087 2088//===--- CHECK: Integer mixed-sign comparisons (-Wsign-compare) --------===// 2089//===--- CHECK: Lossy implicit conversions (-Wconversion) --------------===// 2090 2091namespace { 2092 2093/// Structure recording the 'active' range of an integer-valued 2094/// expression. 2095struct IntRange { 2096 /// The number of bits active in the int. 2097 unsigned Width; 2098 2099 /// True if the int is known not to have negative values. 2100 bool NonNegative; 2101 2102 IntRange() {} 2103 IntRange(unsigned Width, bool NonNegative) 2104 : Width(Width), NonNegative(NonNegative) 2105 {} 2106 2107 // Returns the range of the bool type. 2108 static IntRange forBoolType() { 2109 return IntRange(1, true); 2110 } 2111 2112 // Returns the range of an integral type. 2113 static IntRange forType(ASTContext &C, QualType T) { 2114 return forCanonicalType(C, T->getCanonicalTypeInternal().getTypePtr()); 2115 } 2116 2117 // Returns the range of an integeral type based on its canonical 2118 // representation. 2119 static IntRange forCanonicalType(ASTContext &C, const Type *T) { 2120 assert(T->isCanonicalUnqualified()); 2121 2122 if (const VectorType *VT = dyn_cast<VectorType>(T)) 2123 T = VT->getElementType().getTypePtr(); 2124 if (const ComplexType *CT = dyn_cast<ComplexType>(T)) 2125 T = CT->getElementType().getTypePtr(); 2126 2127 if (const EnumType *ET = dyn_cast<EnumType>(T)) { 2128 EnumDecl *Enum = ET->getDecl(); 2129 unsigned NumPositive = Enum->getNumPositiveBits(); 2130 unsigned NumNegative = Enum->getNumNegativeBits(); 2131 2132 return IntRange(std::max(NumPositive, NumNegative), NumNegative == 0); 2133 } 2134 2135 const BuiltinType *BT = cast<BuiltinType>(T); 2136 assert(BT->isInteger()); 2137 2138 return IntRange(C.getIntWidth(QualType(T, 0)), BT->isUnsignedInteger()); 2139 } 2140 2141 // Returns the supremum of two ranges: i.e. their conservative merge. 2142 static IntRange join(IntRange L, IntRange R) { 2143 return IntRange(std::max(L.Width, R.Width), 2144 L.NonNegative && R.NonNegative); 2145 } 2146 2147 // Returns the infinum of two ranges: i.e. their aggressive merge. 2148 static IntRange meet(IntRange L, IntRange R) { 2149 return IntRange(std::min(L.Width, R.Width), 2150 L.NonNegative || R.NonNegative); 2151 } 2152}; 2153 2154IntRange GetValueRange(ASTContext &C, llvm::APSInt &value, unsigned MaxWidth) { 2155 if (value.isSigned() && value.isNegative()) 2156 return IntRange(value.getMinSignedBits(), false); 2157 2158 if (value.getBitWidth() > MaxWidth) 2159 value.trunc(MaxWidth); 2160 2161 // isNonNegative() just checks the sign bit without considering 2162 // signedness. 2163 return IntRange(value.getActiveBits(), true); 2164} 2165 2166IntRange GetValueRange(ASTContext &C, APValue &result, QualType Ty, 2167 unsigned MaxWidth) { 2168 if (result.isInt()) 2169 return GetValueRange(C, result.getInt(), MaxWidth); 2170 2171 if (result.isVector()) { 2172 IntRange R = GetValueRange(C, result.getVectorElt(0), Ty, MaxWidth); 2173 for (unsigned i = 1, e = result.getVectorLength(); i != e; ++i) { 2174 IntRange El = GetValueRange(C, result.getVectorElt(i), Ty, MaxWidth); 2175 R = IntRange::join(R, El); 2176 } 2177 return R; 2178 } 2179 2180 if (result.isComplexInt()) { 2181 IntRange R = GetValueRange(C, result.getComplexIntReal(), MaxWidth); 2182 IntRange I = GetValueRange(C, result.getComplexIntImag(), MaxWidth); 2183 return IntRange::join(R, I); 2184 } 2185 2186 // This can happen with lossless casts to intptr_t of "based" lvalues. 2187 // Assume it might use arbitrary bits. 2188 // FIXME: The only reason we need to pass the type in here is to get 2189 // the sign right on this one case. It would be nice if APValue 2190 // preserved this. 2191 assert(result.isLValue()); 2192 return IntRange(MaxWidth, Ty->isUnsignedIntegerType()); 2193} 2194 2195/// Pseudo-evaluate the given integer expression, estimating the 2196/// range of values it might take. 2197/// 2198/// \param MaxWidth - the width to which the value will be truncated 2199IntRange GetExprRange(ASTContext &C, Expr *E, unsigned MaxWidth) { 2200 E = E->IgnoreParens(); 2201 2202 // Try a full evaluation first. 2203 Expr::EvalResult result; 2204 if (E->Evaluate(result, C)) 2205 return GetValueRange(C, result.Val, E->getType(), MaxWidth); 2206 2207 // I think we only want to look through implicit casts here; if the 2208 // user has an explicit widening cast, we should treat the value as 2209 // being of the new, wider type. 2210 if (ImplicitCastExpr *CE = dyn_cast<ImplicitCastExpr>(E)) { 2211 if (CE->getCastKind() == CastExpr::CK_NoOp) 2212 return GetExprRange(C, CE->getSubExpr(), MaxWidth); 2213 2214 IntRange OutputTypeRange = IntRange::forType(C, CE->getType()); 2215 2216 bool isIntegerCast = (CE->getCastKind() == CastExpr::CK_IntegralCast); 2217 if (!isIntegerCast && CE->getCastKind() == CastExpr::CK_Unknown) 2218 isIntegerCast = CE->getSubExpr()->getType()->isIntegerType(); 2219 2220 // Assume that non-integer casts can span the full range of the type. 2221 if (!isIntegerCast) 2222 return OutputTypeRange; 2223 2224 IntRange SubRange 2225 = GetExprRange(C, CE->getSubExpr(), 2226 std::min(MaxWidth, OutputTypeRange.Width)); 2227 2228 // Bail out if the subexpr's range is as wide as the cast type. 2229 if (SubRange.Width >= OutputTypeRange.Width) 2230 return OutputTypeRange; 2231 2232 // Otherwise, we take the smaller width, and we're non-negative if 2233 // either the output type or the subexpr is. 2234 return IntRange(SubRange.Width, 2235 SubRange.NonNegative || OutputTypeRange.NonNegative); 2236 } 2237 2238 if (ConditionalOperator *CO = dyn_cast<ConditionalOperator>(E)) { 2239 // If we can fold the condition, just take that operand. 2240 bool CondResult; 2241 if (CO->getCond()->EvaluateAsBooleanCondition(CondResult, C)) 2242 return GetExprRange(C, CondResult ? CO->getTrueExpr() 2243 : CO->getFalseExpr(), 2244 MaxWidth); 2245 2246 // Otherwise, conservatively merge. 2247 IntRange L = GetExprRange(C, CO->getTrueExpr(), MaxWidth); 2248 IntRange R = GetExprRange(C, CO->getFalseExpr(), MaxWidth); 2249 return IntRange::join(L, R); 2250 } 2251 2252 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) { 2253 switch (BO->getOpcode()) { 2254 2255 // Boolean-valued operations are single-bit and positive. 2256 case BinaryOperator::LAnd: 2257 case BinaryOperator::LOr: 2258 case BinaryOperator::LT: 2259 case BinaryOperator::GT: 2260 case BinaryOperator::LE: 2261 case BinaryOperator::GE: 2262 case BinaryOperator::EQ: 2263 case BinaryOperator::NE: 2264 return IntRange::forBoolType(); 2265 2266 // The type of these compound assignments is the type of the LHS, 2267 // so the RHS is not necessarily an integer. 2268 case BinaryOperator::MulAssign: 2269 case BinaryOperator::DivAssign: 2270 case BinaryOperator::RemAssign: 2271 case BinaryOperator::AddAssign: 2272 case BinaryOperator::SubAssign: 2273 return IntRange::forType(C, E->getType()); 2274 2275 // Operations with opaque sources are black-listed. 2276 case BinaryOperator::PtrMemD: 2277 case BinaryOperator::PtrMemI: 2278 return IntRange::forType(C, E->getType()); 2279 2280 // Bitwise-and uses the *infinum* of the two source ranges. 2281 case BinaryOperator::And: 2282 case BinaryOperator::AndAssign: 2283 return IntRange::meet(GetExprRange(C, BO->getLHS(), MaxWidth), 2284 GetExprRange(C, BO->getRHS(), MaxWidth)); 2285 2286 // Left shift gets black-listed based on a judgement call. 2287 case BinaryOperator::Shl: 2288 // ...except that we want to treat '1 << (blah)' as logically 2289 // positive. It's an important idiom. 2290 if (IntegerLiteral *I 2291 = dyn_cast<IntegerLiteral>(BO->getLHS()->IgnoreParenCasts())) { 2292 if (I->getValue() == 1) { 2293 IntRange R = IntRange::forType(C, E->getType()); 2294 return IntRange(R.Width, /*NonNegative*/ true); 2295 } 2296 } 2297 // fallthrough 2298 2299 case BinaryOperator::ShlAssign: 2300 return IntRange::forType(C, E->getType()); 2301 2302 // Right shift by a constant can narrow its left argument. 2303 case BinaryOperator::Shr: 2304 case BinaryOperator::ShrAssign: { 2305 IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth); 2306 2307 // If the shift amount is a positive constant, drop the width by 2308 // that much. 2309 llvm::APSInt shift; 2310 if (BO->getRHS()->isIntegerConstantExpr(shift, C) && 2311 shift.isNonNegative()) { 2312 unsigned zext = shift.getZExtValue(); 2313 if (zext >= L.Width) 2314 L.Width = (L.NonNegative ? 0 : 1); 2315 else 2316 L.Width -= zext; 2317 } 2318 2319 return L; 2320 } 2321 2322 // Comma acts as its right operand. 2323 case BinaryOperator::Comma: 2324 return GetExprRange(C, BO->getRHS(), MaxWidth); 2325 2326 // Black-list pointer subtractions. 2327 case BinaryOperator::Sub: 2328 if (BO->getLHS()->getType()->isPointerType()) 2329 return IntRange::forType(C, E->getType()); 2330 // fallthrough 2331 2332 default: 2333 break; 2334 } 2335 2336 // Treat every other operator as if it were closed on the 2337 // narrowest type that encompasses both operands. 2338 IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth); 2339 IntRange R = GetExprRange(C, BO->getRHS(), MaxWidth); 2340 return IntRange::join(L, R); 2341 } 2342 2343 if (UnaryOperator *UO = dyn_cast<UnaryOperator>(E)) { 2344 switch (UO->getOpcode()) { 2345 // Boolean-valued operations are white-listed. 2346 case UnaryOperator::LNot: 2347 return IntRange::forBoolType(); 2348 2349 // Operations with opaque sources are black-listed. 2350 case UnaryOperator::Deref: 2351 case UnaryOperator::AddrOf: // should be impossible 2352 case UnaryOperator::OffsetOf: 2353 return IntRange::forType(C, E->getType()); 2354 2355 default: 2356 return GetExprRange(C, UO->getSubExpr(), MaxWidth); 2357 } 2358 } 2359 2360 if (dyn_cast<OffsetOfExpr>(E)) { 2361 IntRange::forType(C, E->getType()); 2362 } 2363 2364 FieldDecl *BitField = E->getBitField(); 2365 if (BitField) { 2366 llvm::APSInt BitWidthAP = BitField->getBitWidth()->EvaluateAsInt(C); 2367 unsigned BitWidth = BitWidthAP.getZExtValue(); 2368 2369 return IntRange(BitWidth, BitField->getType()->isUnsignedIntegerType()); 2370 } 2371 2372 return IntRange::forType(C, E->getType()); 2373} 2374 2375IntRange GetExprRange(ASTContext &C, Expr *E) { 2376 return GetExprRange(C, E, C.getIntWidth(E->getType())); 2377} 2378 2379/// Checks whether the given value, which currently has the given 2380/// source semantics, has the same value when coerced through the 2381/// target semantics. 2382bool IsSameFloatAfterCast(const llvm::APFloat &value, 2383 const llvm::fltSemantics &Src, 2384 const llvm::fltSemantics &Tgt) { 2385 llvm::APFloat truncated = value; 2386 2387 bool ignored; 2388 truncated.convert(Src, llvm::APFloat::rmNearestTiesToEven, &ignored); 2389 truncated.convert(Tgt, llvm::APFloat::rmNearestTiesToEven, &ignored); 2390 2391 return truncated.bitwiseIsEqual(value); 2392} 2393 2394/// Checks whether the given value, which currently has the given 2395/// source semantics, has the same value when coerced through the 2396/// target semantics. 2397/// 2398/// The value might be a vector of floats (or a complex number). 2399bool IsSameFloatAfterCast(const APValue &value, 2400 const llvm::fltSemantics &Src, 2401 const llvm::fltSemantics &Tgt) { 2402 if (value.isFloat()) 2403 return IsSameFloatAfterCast(value.getFloat(), Src, Tgt); 2404 2405 if (value.isVector()) { 2406 for (unsigned i = 0, e = value.getVectorLength(); i != e; ++i) 2407 if (!IsSameFloatAfterCast(value.getVectorElt(i), Src, Tgt)) 2408 return false; 2409 return true; 2410 } 2411 2412 assert(value.isComplexFloat()); 2413 return (IsSameFloatAfterCast(value.getComplexFloatReal(), Src, Tgt) && 2414 IsSameFloatAfterCast(value.getComplexFloatImag(), Src, Tgt)); 2415} 2416 2417void AnalyzeImplicitConversions(Sema &S, Expr *E); 2418 2419bool IsZero(Sema &S, Expr *E) { 2420 llvm::APSInt Value; 2421 return E->isIntegerConstantExpr(Value, S.Context) && Value == 0; 2422} 2423 2424void CheckTrivialUnsignedComparison(Sema &S, BinaryOperator *E) { 2425 BinaryOperator::Opcode op = E->getOpcode(); 2426 if (op == BinaryOperator::LT && IsZero(S, E->getRHS())) { 2427 S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison) 2428 << "< 0" << "false" 2429 << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); 2430 } else if (op == BinaryOperator::GE && IsZero(S, E->getRHS())) { 2431 S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison) 2432 << ">= 0" << "true" 2433 << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); 2434 } else if (op == BinaryOperator::GT && IsZero(S, E->getLHS())) { 2435 S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison) 2436 << "0 >" << "false" 2437 << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); 2438 } else if (op == BinaryOperator::LE && IsZero(S, E->getLHS())) { 2439 S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison) 2440 << "0 <=" << "true" 2441 << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); 2442 } 2443} 2444 2445/// Analyze the operands of the given comparison. Implements the 2446/// fallback case from AnalyzeComparison. 2447void AnalyzeImpConvsInComparison(Sema &S, BinaryOperator *E) { 2448 AnalyzeImplicitConversions(S, E->getLHS()); 2449 AnalyzeImplicitConversions(S, E->getRHS()); 2450} 2451 2452/// \brief Implements -Wsign-compare. 2453/// 2454/// \param lex the left-hand expression 2455/// \param rex the right-hand expression 2456/// \param OpLoc the location of the joining operator 2457/// \param BinOpc binary opcode or 0 2458void AnalyzeComparison(Sema &S, BinaryOperator *E) { 2459 // The type the comparison is being performed in. 2460 QualType T = E->getLHS()->getType(); 2461 assert(S.Context.hasSameUnqualifiedType(T, E->getRHS()->getType()) 2462 && "comparison with mismatched types"); 2463 2464 // We don't do anything special if this isn't an unsigned integral 2465 // comparison: we're only interested in integral comparisons, and 2466 // signed comparisons only happen in cases we don't care to warn about. 2467 if (!T->hasUnsignedIntegerRepresentation()) 2468 return AnalyzeImpConvsInComparison(S, E); 2469 2470 Expr *lex = E->getLHS()->IgnoreParenImpCasts(); 2471 Expr *rex = E->getRHS()->IgnoreParenImpCasts(); 2472 2473 // Check to see if one of the (unmodified) operands is of different 2474 // signedness. 2475 Expr *signedOperand, *unsignedOperand; 2476 if (lex->getType()->hasSignedIntegerRepresentation()) { 2477 assert(!rex->getType()->hasSignedIntegerRepresentation() && 2478 "unsigned comparison between two signed integer expressions?"); 2479 signedOperand = lex; 2480 unsignedOperand = rex; 2481 } else if (rex->getType()->hasSignedIntegerRepresentation()) { 2482 signedOperand = rex; 2483 unsignedOperand = lex; 2484 } else { 2485 CheckTrivialUnsignedComparison(S, E); 2486 return AnalyzeImpConvsInComparison(S, E); 2487 } 2488 2489 // Otherwise, calculate the effective range of the signed operand. 2490 IntRange signedRange = GetExprRange(S.Context, signedOperand); 2491 2492 // Go ahead and analyze implicit conversions in the operands. Note 2493 // that we skip the implicit conversions on both sides. 2494 AnalyzeImplicitConversions(S, lex); 2495 AnalyzeImplicitConversions(S, rex); 2496 2497 // If the signed range is non-negative, -Wsign-compare won't fire, 2498 // but we should still check for comparisons which are always true 2499 // or false. 2500 if (signedRange.NonNegative) 2501 return CheckTrivialUnsignedComparison(S, E); 2502 2503 // For (in)equality comparisons, if the unsigned operand is a 2504 // constant which cannot collide with a overflowed signed operand, 2505 // then reinterpreting the signed operand as unsigned will not 2506 // change the result of the comparison. 2507 if (E->isEqualityOp()) { 2508 unsigned comparisonWidth = S.Context.getIntWidth(T); 2509 IntRange unsignedRange = GetExprRange(S.Context, unsignedOperand); 2510 2511 // We should never be unable to prove that the unsigned operand is 2512 // non-negative. 2513 assert(unsignedRange.NonNegative && "unsigned range includes negative?"); 2514 2515 if (unsignedRange.Width < comparisonWidth) 2516 return; 2517 } 2518 2519 S.Diag(E->getOperatorLoc(), diag::warn_mixed_sign_comparison) 2520 << lex->getType() << rex->getType() 2521 << lex->getSourceRange() << rex->getSourceRange(); 2522} 2523 2524/// Diagnose an implicit cast; purely a helper for CheckImplicitConversion. 2525void DiagnoseImpCast(Sema &S, Expr *E, QualType T, unsigned diag) { 2526 S.Diag(E->getExprLoc(), diag) << E->getType() << T << E->getSourceRange(); 2527} 2528 2529void CheckImplicitConversion(Sema &S, Expr *E, QualType T, 2530 bool *ICContext = 0) { 2531 if (E->isTypeDependent() || E->isValueDependent()) return; 2532 2533 const Type *Source = S.Context.getCanonicalType(E->getType()).getTypePtr(); 2534 const Type *Target = S.Context.getCanonicalType(T).getTypePtr(); 2535 if (Source == Target) return; 2536 if (Target->isDependentType()) return; 2537 2538 // Never diagnose implicit casts to bool. 2539 if (Target->isSpecificBuiltinType(BuiltinType::Bool)) 2540 return; 2541 2542 // Strip vector types. 2543 if (isa<VectorType>(Source)) { 2544 if (!isa<VectorType>(Target)) 2545 return DiagnoseImpCast(S, E, T, diag::warn_impcast_vector_scalar); 2546 2547 Source = cast<VectorType>(Source)->getElementType().getTypePtr(); 2548 Target = cast<VectorType>(Target)->getElementType().getTypePtr(); 2549 } 2550 2551 // Strip complex types. 2552 if (isa<ComplexType>(Source)) { 2553 if (!isa<ComplexType>(Target)) 2554 return DiagnoseImpCast(S, E, T, diag::warn_impcast_complex_scalar); 2555 2556 Source = cast<ComplexType>(Source)->getElementType().getTypePtr(); 2557 Target = cast<ComplexType>(Target)->getElementType().getTypePtr(); 2558 } 2559 2560 const BuiltinType *SourceBT = dyn_cast<BuiltinType>(Source); 2561 const BuiltinType *TargetBT = dyn_cast<BuiltinType>(Target); 2562 2563 // If the source is floating point... 2564 if (SourceBT && SourceBT->isFloatingPoint()) { 2565 // ...and the target is floating point... 2566 if (TargetBT && TargetBT->isFloatingPoint()) { 2567 // ...then warn if we're dropping FP rank. 2568 2569 // Builtin FP kinds are ordered by increasing FP rank. 2570 if (SourceBT->getKind() > TargetBT->getKind()) { 2571 // Don't warn about float constants that are precisely 2572 // representable in the target type. 2573 Expr::EvalResult result; 2574 if (E->Evaluate(result, S.Context)) { 2575 // Value might be a float, a float vector, or a float complex. 2576 if (IsSameFloatAfterCast(result.Val, 2577 S.Context.getFloatTypeSemantics(QualType(TargetBT, 0)), 2578 S.Context.getFloatTypeSemantics(QualType(SourceBT, 0)))) 2579 return; 2580 } 2581 2582 DiagnoseImpCast(S, E, T, diag::warn_impcast_float_precision); 2583 } 2584 return; 2585 } 2586 2587 // If the target is integral, always warn. 2588 if ((TargetBT && TargetBT->isInteger())) 2589 // TODO: don't warn for integer values? 2590 DiagnoseImpCast(S, E, T, diag::warn_impcast_float_integer); 2591 2592 return; 2593 } 2594 2595 if (!Source->isIntegerType() || !Target->isIntegerType()) 2596 return; 2597 2598 IntRange SourceRange = GetExprRange(S.Context, E); 2599 IntRange TargetRange = IntRange::forCanonicalType(S.Context, Target); 2600 2601 if (SourceRange.Width > TargetRange.Width) { 2602 // People want to build with -Wshorten-64-to-32 and not -Wconversion 2603 // and by god we'll let them. 2604 if (SourceRange.Width == 64 && TargetRange.Width == 32) 2605 return DiagnoseImpCast(S, E, T, diag::warn_impcast_integer_64_32); 2606 return DiagnoseImpCast(S, E, T, diag::warn_impcast_integer_precision); 2607 } 2608 2609 if ((TargetRange.NonNegative && !SourceRange.NonNegative) || 2610 (!TargetRange.NonNegative && SourceRange.NonNegative && 2611 SourceRange.Width == TargetRange.Width)) { 2612 unsigned DiagID = diag::warn_impcast_integer_sign; 2613 2614 // Traditionally, gcc has warned about this under -Wsign-compare. 2615 // We also want to warn about it in -Wconversion. 2616 // So if -Wconversion is off, use a completely identical diagnostic 2617 // in the sign-compare group. 2618 // The conditional-checking code will 2619 if (ICContext) { 2620 DiagID = diag::warn_impcast_integer_sign_conditional; 2621 *ICContext = true; 2622 } 2623 2624 return DiagnoseImpCast(S, E, T, DiagID); 2625 } 2626 2627 return; 2628} 2629 2630void CheckConditionalOperator(Sema &S, ConditionalOperator *E, QualType T); 2631 2632void CheckConditionalOperand(Sema &S, Expr *E, QualType T, 2633 bool &ICContext) { 2634 E = E->IgnoreParenImpCasts(); 2635 2636 if (isa<ConditionalOperator>(E)) 2637 return CheckConditionalOperator(S, cast<ConditionalOperator>(E), T); 2638 2639 AnalyzeImplicitConversions(S, E); 2640 if (E->getType() != T) 2641 return CheckImplicitConversion(S, E, T, &ICContext); 2642 return; 2643} 2644 2645void CheckConditionalOperator(Sema &S, ConditionalOperator *E, QualType T) { 2646 AnalyzeImplicitConversions(S, E->getCond()); 2647 2648 bool Suspicious = false; 2649 CheckConditionalOperand(S, E->getTrueExpr(), T, Suspicious); 2650 CheckConditionalOperand(S, E->getFalseExpr(), T, Suspicious); 2651 2652 // If -Wconversion would have warned about either of the candidates 2653 // for a signedness conversion to the context type... 2654 if (!Suspicious) return; 2655 2656 // ...but it's currently ignored... 2657 if (S.Diags.getDiagnosticLevel(diag::warn_impcast_integer_sign_conditional)) 2658 return; 2659 2660 // ...and -Wsign-compare isn't... 2661 if (!S.Diags.getDiagnosticLevel(diag::warn_mixed_sign_conditional)) 2662 return; 2663 2664 // ...then check whether it would have warned about either of the 2665 // candidates for a signedness conversion to the condition type. 2666 if (E->getType() != T) { 2667 Suspicious = false; 2668 CheckImplicitConversion(S, E->getTrueExpr()->IgnoreParenImpCasts(), 2669 E->getType(), &Suspicious); 2670 if (!Suspicious) 2671 CheckImplicitConversion(S, E->getFalseExpr()->IgnoreParenImpCasts(), 2672 E->getType(), &Suspicious); 2673 if (!Suspicious) 2674 return; 2675 } 2676 2677 // If so, emit a diagnostic under -Wsign-compare. 2678 Expr *lex = E->getTrueExpr()->IgnoreParenImpCasts(); 2679 Expr *rex = E->getFalseExpr()->IgnoreParenImpCasts(); 2680 S.Diag(E->getQuestionLoc(), diag::warn_mixed_sign_conditional) 2681 << lex->getType() << rex->getType() 2682 << lex->getSourceRange() << rex->getSourceRange(); 2683} 2684 2685/// AnalyzeImplicitConversions - Find and report any interesting 2686/// implicit conversions in the given expression. There are a couple 2687/// of competing diagnostics here, -Wconversion and -Wsign-compare. 2688void AnalyzeImplicitConversions(Sema &S, Expr *OrigE) { 2689 QualType T = OrigE->getType(); 2690 Expr *E = OrigE->IgnoreParenImpCasts(); 2691 2692 // For conditional operators, we analyze the arguments as if they 2693 // were being fed directly into the output. 2694 if (isa<ConditionalOperator>(E)) { 2695 ConditionalOperator *CO = cast<ConditionalOperator>(E); 2696 CheckConditionalOperator(S, CO, T); 2697 return; 2698 } 2699 2700 // Go ahead and check any implicit conversions we might have skipped. 2701 // The non-canonical typecheck is just an optimization; 2702 // CheckImplicitConversion will filter out dead implicit conversions. 2703 if (E->getType() != T) 2704 CheckImplicitConversion(S, E, T); 2705 2706 // Now continue drilling into this expression. 2707 2708 // Skip past explicit casts. 2709 if (isa<ExplicitCastExpr>(E)) { 2710 E = cast<ExplicitCastExpr>(E)->getSubExpr()->IgnoreParenImpCasts(); 2711 return AnalyzeImplicitConversions(S, E); 2712 } 2713 2714 // Do a somewhat different check with comparison operators. 2715 if (isa<BinaryOperator>(E) && cast<BinaryOperator>(E)->isComparisonOp()) 2716 return AnalyzeComparison(S, cast<BinaryOperator>(E)); 2717 2718 // These break the otherwise-useful invariant below. Fortunately, 2719 // we don't really need to recurse into them, because any internal 2720 // expressions should have been analyzed already when they were 2721 // built into statements. 2722 if (isa<StmtExpr>(E)) return; 2723 2724 // Don't descend into unevaluated contexts. 2725 if (isa<SizeOfAlignOfExpr>(E)) return; 2726 2727 // Now just recurse over the expression's children. 2728 for (Stmt::child_iterator I = E->child_begin(), IE = E->child_end(); 2729 I != IE; ++I) 2730 AnalyzeImplicitConversions(S, cast<Expr>(*I)); 2731} 2732 2733} // end anonymous namespace 2734 2735/// Diagnoses "dangerous" implicit conversions within the given 2736/// expression (which is a full expression). Implements -Wconversion 2737/// and -Wsign-compare. 2738void Sema::CheckImplicitConversions(Expr *E) { 2739 // Don't diagnose in unevaluated contexts. 2740 if (ExprEvalContexts.back().Context == Sema::Unevaluated) 2741 return; 2742 2743 // Don't diagnose for value- or type-dependent expressions. 2744 if (E->isTypeDependent() || E->isValueDependent()) 2745 return; 2746 2747 AnalyzeImplicitConversions(*this, E); 2748} 2749 2750/// CheckParmsForFunctionDef - Check that the parameters of the given 2751/// function are appropriate for the definition of a function. This 2752/// takes care of any checks that cannot be performed on the 2753/// declaration itself, e.g., that the types of each of the function 2754/// parameters are complete. 2755bool Sema::CheckParmsForFunctionDef(FunctionDecl *FD) { 2756 bool HasInvalidParm = false; 2757 for (unsigned p = 0, NumParams = FD->getNumParams(); p < NumParams; ++p) { 2758 ParmVarDecl *Param = FD->getParamDecl(p); 2759 2760 // C99 6.7.5.3p4: the parameters in a parameter type list in a 2761 // function declarator that is part of a function definition of 2762 // that function shall not have incomplete type. 2763 // 2764 // This is also C++ [dcl.fct]p6. 2765 if (!Param->isInvalidDecl() && 2766 RequireCompleteType(Param->getLocation(), Param->getType(), 2767 diag::err_typecheck_decl_incomplete_type)) { 2768 Param->setInvalidDecl(); 2769 HasInvalidParm = true; 2770 } 2771 2772 // C99 6.9.1p5: If the declarator includes a parameter type list, the 2773 // declaration of each parameter shall include an identifier. 2774 if (Param->getIdentifier() == 0 && 2775 !Param->isImplicit() && 2776 !getLangOptions().CPlusPlus) 2777 Diag(Param->getLocation(), diag::err_parameter_name_omitted); 2778 2779 // C99 6.7.5.3p12: 2780 // If the function declarator is not part of a definition of that 2781 // function, parameters may have incomplete type and may use the [*] 2782 // notation in their sequences of declarator specifiers to specify 2783 // variable length array types. 2784 QualType PType = Param->getOriginalType(); 2785 if (const ArrayType *AT = Context.getAsArrayType(PType)) { 2786 if (AT->getSizeModifier() == ArrayType::Star) { 2787 // FIXME: This diagnosic should point the the '[*]' if source-location 2788 // information is added for it. 2789 Diag(Param->getLocation(), diag::err_array_star_in_function_definition); 2790 } 2791 } 2792 } 2793 2794 return HasInvalidParm; 2795} 2796