SemaChecking.cpp revision 8d13d221cf7c1657404c611efaadf3ac19d899b3
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 ICE->Destroy(Context); 534 TheCall->setArg(i+1, Arg); 535 } 536 537 // GCC does an implicit conversion to the pointer or integer ValType. This 538 // can fail in some cases (1i -> int**), check for this error case now. 539 CastExpr::CastKind Kind = CastExpr::CK_Unknown; 540 CXXBaseSpecifierArray BasePath; 541 if (CheckCastTypes(Arg->getSourceRange(), ValType, Arg, Kind, BasePath)) 542 return ExprError(); 543 544 // Okay, we have something that *can* be converted to the right type. Check 545 // to see if there is a potentially weird extension going on here. This can 546 // happen when you do an atomic operation on something like an char* and 547 // pass in 42. The 42 gets converted to char. This is even more strange 548 // for things like 45.123 -> char, etc. 549 // FIXME: Do this check. 550 ImpCastExprToType(Arg, ValType, Kind); 551 TheCall->setArg(i+1, Arg); 552 } 553 554 // Switch the DeclRefExpr to refer to the new decl. 555 DRE->setDecl(NewBuiltinDecl); 556 DRE->setType(NewBuiltinDecl->getType()); 557 558 // Set the callee in the CallExpr. 559 // FIXME: This leaks the original parens and implicit casts. 560 Expr *PromotedCall = DRE; 561 UsualUnaryConversions(PromotedCall); 562 TheCall->setCallee(PromotedCall); 563 564 // Change the result type of the call to match the original value type. This 565 // is arbitrary, but the codegen for these builtins ins design to handle it 566 // gracefully. 567 TheCall->setType(ResultType); 568 569 return move(TheCallResult); 570} 571 572 573/// CheckObjCString - Checks that the argument to the builtin 574/// CFString constructor is correct 575/// FIXME: GCC currently emits the following warning: 576/// "warning: input conversion stopped due to an input byte that does not 577/// belong to the input codeset UTF-8" 578/// Note: It might also make sense to do the UTF-16 conversion here (would 579/// simplify the backend). 580bool Sema::CheckObjCString(Expr *Arg) { 581 Arg = Arg->IgnoreParenCasts(); 582 StringLiteral *Literal = dyn_cast<StringLiteral>(Arg); 583 584 if (!Literal || Literal->isWide()) { 585 Diag(Arg->getLocStart(), diag::err_cfstring_literal_not_string_constant) 586 << Arg->getSourceRange(); 587 return true; 588 } 589 590 const char *Data = Literal->getStrData(); 591 unsigned Length = Literal->getByteLength(); 592 593 for (unsigned i = 0; i < Length; ++i) { 594 if (!Data[i]) { 595 Diag(getLocationOfStringLiteralByte(Literal, i), 596 diag::warn_cfstring_literal_contains_nul_character) 597 << Arg->getSourceRange(); 598 break; 599 } 600 } 601 602 return false; 603} 604 605/// SemaBuiltinVAStart - Check the arguments to __builtin_va_start for validity. 606/// Emit an error and return true on failure, return false on success. 607bool Sema::SemaBuiltinVAStart(CallExpr *TheCall) { 608 Expr *Fn = TheCall->getCallee(); 609 if (TheCall->getNumArgs() > 2) { 610 Diag(TheCall->getArg(2)->getLocStart(), 611 diag::err_typecheck_call_too_many_args) 612 << 0 /*function call*/ << 2 << TheCall->getNumArgs() 613 << Fn->getSourceRange() 614 << SourceRange(TheCall->getArg(2)->getLocStart(), 615 (*(TheCall->arg_end()-1))->getLocEnd()); 616 return true; 617 } 618 619 if (TheCall->getNumArgs() < 2) { 620 return Diag(TheCall->getLocEnd(), 621 diag::err_typecheck_call_too_few_args_at_least) 622 << 0 /*function call*/ << 2 << TheCall->getNumArgs(); 623 } 624 625 // Determine whether the current function is variadic or not. 626 BlockScopeInfo *CurBlock = getCurBlock(); 627 bool isVariadic; 628 if (CurBlock) 629 isVariadic = CurBlock->TheDecl->isVariadic(); 630 else if (FunctionDecl *FD = getCurFunctionDecl()) 631 isVariadic = FD->isVariadic(); 632 else 633 isVariadic = getCurMethodDecl()->isVariadic(); 634 635 if (!isVariadic) { 636 Diag(Fn->getLocStart(), diag::err_va_start_used_in_non_variadic_function); 637 return true; 638 } 639 640 // Verify that the second argument to the builtin is the last argument of the 641 // current function or method. 642 bool SecondArgIsLastNamedArgument = false; 643 const Expr *Arg = TheCall->getArg(1)->IgnoreParenCasts(); 644 645 if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Arg)) { 646 if (const ParmVarDecl *PV = dyn_cast<ParmVarDecl>(DR->getDecl())) { 647 // FIXME: This isn't correct for methods (results in bogus warning). 648 // Get the last formal in the current function. 649 const ParmVarDecl *LastArg; 650 if (CurBlock) 651 LastArg = *(CurBlock->TheDecl->param_end()-1); 652 else if (FunctionDecl *FD = getCurFunctionDecl()) 653 LastArg = *(FD->param_end()-1); 654 else 655 LastArg = *(getCurMethodDecl()->param_end()-1); 656 SecondArgIsLastNamedArgument = PV == LastArg; 657 } 658 } 659 660 if (!SecondArgIsLastNamedArgument) 661 Diag(TheCall->getArg(1)->getLocStart(), 662 diag::warn_second_parameter_of_va_start_not_last_named_argument); 663 return false; 664} 665 666/// SemaBuiltinUnorderedCompare - Handle functions like __builtin_isgreater and 667/// friends. This is declared to take (...), so we have to check everything. 668bool Sema::SemaBuiltinUnorderedCompare(CallExpr *TheCall) { 669 if (TheCall->getNumArgs() < 2) 670 return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args) 671 << 0 << 2 << TheCall->getNumArgs()/*function call*/; 672 if (TheCall->getNumArgs() > 2) 673 return Diag(TheCall->getArg(2)->getLocStart(), 674 diag::err_typecheck_call_too_many_args) 675 << 0 /*function call*/ << 2 << TheCall->getNumArgs() 676 << SourceRange(TheCall->getArg(2)->getLocStart(), 677 (*(TheCall->arg_end()-1))->getLocEnd()); 678 679 Expr *OrigArg0 = TheCall->getArg(0); 680 Expr *OrigArg1 = TheCall->getArg(1); 681 682 // Do standard promotions between the two arguments, returning their common 683 // type. 684 QualType Res = UsualArithmeticConversions(OrigArg0, OrigArg1, false); 685 686 // Make sure any conversions are pushed back into the call; this is 687 // type safe since unordered compare builtins are declared as "_Bool 688 // foo(...)". 689 TheCall->setArg(0, OrigArg0); 690 TheCall->setArg(1, OrigArg1); 691 692 if (OrigArg0->isTypeDependent() || OrigArg1->isTypeDependent()) 693 return false; 694 695 // If the common type isn't a real floating type, then the arguments were 696 // invalid for this operation. 697 if (!Res->isRealFloatingType()) 698 return Diag(OrigArg0->getLocStart(), 699 diag::err_typecheck_call_invalid_ordered_compare) 700 << OrigArg0->getType() << OrigArg1->getType() 701 << SourceRange(OrigArg0->getLocStart(), OrigArg1->getLocEnd()); 702 703 return false; 704} 705 706/// SemaBuiltinSemaBuiltinFPClassification - Handle functions like 707/// __builtin_isnan and friends. This is declared to take (...), so we have 708/// to check everything. We expect the last argument to be a floating point 709/// value. 710bool Sema::SemaBuiltinFPClassification(CallExpr *TheCall, unsigned NumArgs) { 711 if (TheCall->getNumArgs() < NumArgs) 712 return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args) 713 << 0 << NumArgs << TheCall->getNumArgs()/*function call*/; 714 if (TheCall->getNumArgs() > NumArgs) 715 return Diag(TheCall->getArg(NumArgs)->getLocStart(), 716 diag::err_typecheck_call_too_many_args) 717 << 0 /*function call*/ << NumArgs << TheCall->getNumArgs() 718 << SourceRange(TheCall->getArg(NumArgs)->getLocStart(), 719 (*(TheCall->arg_end()-1))->getLocEnd()); 720 721 Expr *OrigArg = TheCall->getArg(NumArgs-1); 722 723 if (OrigArg->isTypeDependent()) 724 return false; 725 726 // This operation requires a non-_Complex floating-point number. 727 if (!OrigArg->getType()->isRealFloatingType()) 728 return Diag(OrigArg->getLocStart(), 729 diag::err_typecheck_call_invalid_unary_fp) 730 << OrigArg->getType() << OrigArg->getSourceRange(); 731 732 // If this is an implicit conversion from float -> double, remove it. 733 if (ImplicitCastExpr *Cast = dyn_cast<ImplicitCastExpr>(OrigArg)) { 734 Expr *CastArg = Cast->getSubExpr(); 735 if (CastArg->getType()->isSpecificBuiltinType(BuiltinType::Float)) { 736 assert(Cast->getType()->isSpecificBuiltinType(BuiltinType::Double) && 737 "promotion from float to double is the only expected cast here"); 738 Cast->setSubExpr(0); 739 Cast->Destroy(Context); 740 TheCall->setArg(NumArgs-1, CastArg); 741 OrigArg = CastArg; 742 } 743 } 744 745 return false; 746} 747 748/// SemaBuiltinShuffleVector - Handle __builtin_shufflevector. 749// This is declared to take (...), so we have to check everything. 750Action::OwningExprResult Sema::SemaBuiltinShuffleVector(CallExpr *TheCall) { 751 if (TheCall->getNumArgs() < 2) 752 return ExprError(Diag(TheCall->getLocEnd(), 753 diag::err_typecheck_call_too_few_args_at_least) 754 << 0 /*function call*/ << 2 << TheCall->getNumArgs() 755 << TheCall->getSourceRange()); 756 757 // Determine which of the following types of shufflevector we're checking: 758 // 1) unary, vector mask: (lhs, mask) 759 // 2) binary, vector mask: (lhs, rhs, mask) 760 // 3) binary, scalar mask: (lhs, rhs, index, ..., index) 761 QualType resType = TheCall->getArg(0)->getType(); 762 unsigned numElements = 0; 763 764 if (!TheCall->getArg(0)->isTypeDependent() && 765 !TheCall->getArg(1)->isTypeDependent()) { 766 QualType LHSType = TheCall->getArg(0)->getType(); 767 QualType RHSType = TheCall->getArg(1)->getType(); 768 769 if (!LHSType->isVectorType() || !RHSType->isVectorType()) { 770 Diag(TheCall->getLocStart(), diag::err_shufflevector_non_vector) 771 << SourceRange(TheCall->getArg(0)->getLocStart(), 772 TheCall->getArg(1)->getLocEnd()); 773 return ExprError(); 774 } 775 776 numElements = LHSType->getAs<VectorType>()->getNumElements(); 777 unsigned numResElements = TheCall->getNumArgs() - 2; 778 779 // Check to see if we have a call with 2 vector arguments, the unary shuffle 780 // with mask. If so, verify that RHS is an integer vector type with the 781 // same number of elts as lhs. 782 if (TheCall->getNumArgs() == 2) { 783 if (!RHSType->isIntegerType() || 784 RHSType->getAs<VectorType>()->getNumElements() != numElements) 785 Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector) 786 << SourceRange(TheCall->getArg(1)->getLocStart(), 787 TheCall->getArg(1)->getLocEnd()); 788 numResElements = numElements; 789 } 790 else if (!Context.hasSameUnqualifiedType(LHSType, RHSType)) { 791 Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector) 792 << SourceRange(TheCall->getArg(0)->getLocStart(), 793 TheCall->getArg(1)->getLocEnd()); 794 return ExprError(); 795 } else if (numElements != numResElements) { 796 QualType eltType = LHSType->getAs<VectorType>()->getElementType(); 797 resType = Context.getVectorType(eltType, numResElements, 798 VectorType::NotAltiVec); 799 } 800 } 801 802 for (unsigned i = 2; i < TheCall->getNumArgs(); i++) { 803 if (TheCall->getArg(i)->isTypeDependent() || 804 TheCall->getArg(i)->isValueDependent()) 805 continue; 806 807 llvm::APSInt Result(32); 808 if (!TheCall->getArg(i)->isIntegerConstantExpr(Result, Context)) 809 return ExprError(Diag(TheCall->getLocStart(), 810 diag::err_shufflevector_nonconstant_argument) 811 << TheCall->getArg(i)->getSourceRange()); 812 813 if (Result.getActiveBits() > 64 || Result.getZExtValue() >= numElements*2) 814 return ExprError(Diag(TheCall->getLocStart(), 815 diag::err_shufflevector_argument_too_large) 816 << TheCall->getArg(i)->getSourceRange()); 817 } 818 819 llvm::SmallVector<Expr*, 32> exprs; 820 821 for (unsigned i = 0, e = TheCall->getNumArgs(); i != e; i++) { 822 exprs.push_back(TheCall->getArg(i)); 823 TheCall->setArg(i, 0); 824 } 825 826 return Owned(new (Context) ShuffleVectorExpr(Context, exprs.begin(), 827 exprs.size(), resType, 828 TheCall->getCallee()->getLocStart(), 829 TheCall->getRParenLoc())); 830} 831 832/// SemaBuiltinPrefetch - Handle __builtin_prefetch. 833// This is declared to take (const void*, ...) and can take two 834// optional constant int args. 835bool Sema::SemaBuiltinPrefetch(CallExpr *TheCall) { 836 unsigned NumArgs = TheCall->getNumArgs(); 837 838 if (NumArgs > 3) 839 return Diag(TheCall->getLocEnd(), 840 diag::err_typecheck_call_too_many_args_at_most) 841 << 0 /*function call*/ << 3 << NumArgs 842 << TheCall->getSourceRange(); 843 844 // Argument 0 is checked for us and the remaining arguments must be 845 // constant integers. 846 for (unsigned i = 1; i != NumArgs; ++i) { 847 Expr *Arg = TheCall->getArg(i); 848 849 llvm::APSInt Result; 850 if (SemaBuiltinConstantArg(TheCall, i, Result)) 851 return true; 852 853 // FIXME: gcc issues a warning and rewrites these to 0. These 854 // seems especially odd for the third argument since the default 855 // is 3. 856 if (i == 1) { 857 if (Result.getLimitedValue() > 1) 858 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 859 << "0" << "1" << Arg->getSourceRange(); 860 } else { 861 if (Result.getLimitedValue() > 3) 862 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 863 << "0" << "3" << Arg->getSourceRange(); 864 } 865 } 866 867 return false; 868} 869 870/// SemaBuiltinConstantArg - Handle a check if argument ArgNum of CallExpr 871/// TheCall is a constant expression. 872bool Sema::SemaBuiltinConstantArg(CallExpr *TheCall, int ArgNum, 873 llvm::APSInt &Result) { 874 Expr *Arg = TheCall->getArg(ArgNum); 875 DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts()); 876 FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl()); 877 878 if (Arg->isTypeDependent() || Arg->isValueDependent()) return false; 879 880 if (!Arg->isIntegerConstantExpr(Result, Context)) 881 return Diag(TheCall->getLocStart(), diag::err_constant_integer_arg_type) 882 << FDecl->getDeclName() << Arg->getSourceRange(); 883 884 return false; 885} 886 887/// SemaBuiltinObjectSize - Handle __builtin_object_size(void *ptr, 888/// int type). This simply type checks that type is one of the defined 889/// constants (0-3). 890// For compatability check 0-3, llvm only handles 0 and 2. 891bool Sema::SemaBuiltinObjectSize(CallExpr *TheCall) { 892 llvm::APSInt Result; 893 894 // Check constant-ness first. 895 if (SemaBuiltinConstantArg(TheCall, 1, Result)) 896 return true; 897 898 Expr *Arg = TheCall->getArg(1); 899 if (Result.getSExtValue() < 0 || Result.getSExtValue() > 3) { 900 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 901 << "0" << "3" << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); 902 } 903 904 return false; 905} 906 907/// SemaBuiltinLongjmp - Handle __builtin_longjmp(void *env[5], int val). 908/// This checks that val is a constant 1. 909bool Sema::SemaBuiltinLongjmp(CallExpr *TheCall) { 910 Expr *Arg = TheCall->getArg(1); 911 llvm::APSInt Result; 912 913 // TODO: This is less than ideal. Overload this to take a value. 914 if (SemaBuiltinConstantArg(TheCall, 1, Result)) 915 return true; 916 917 if (Result != 1) 918 return Diag(TheCall->getLocStart(), diag::err_builtin_longjmp_invalid_val) 919 << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); 920 921 return false; 922} 923 924// Handle i > 1 ? "x" : "y", recursivelly 925bool Sema::SemaCheckStringLiteral(const Expr *E, const CallExpr *TheCall, 926 bool HasVAListArg, 927 unsigned format_idx, unsigned firstDataArg, 928 bool isPrintf) { 929 930 if (E->isTypeDependent() || E->isValueDependent()) 931 return false; 932 933 switch (E->getStmtClass()) { 934 case Stmt::ConditionalOperatorClass: { 935 const ConditionalOperator *C = cast<ConditionalOperator>(E); 936 return SemaCheckStringLiteral(C->getTrueExpr(), TheCall, HasVAListArg, 937 format_idx, firstDataArg, isPrintf) 938 && SemaCheckStringLiteral(C->getRHS(), TheCall, HasVAListArg, 939 format_idx, firstDataArg, isPrintf); 940 } 941 942 case Stmt::ImplicitCastExprClass: { 943 const ImplicitCastExpr *Expr = cast<ImplicitCastExpr>(E); 944 return SemaCheckStringLiteral(Expr->getSubExpr(), TheCall, HasVAListArg, 945 format_idx, firstDataArg, isPrintf); 946 } 947 948 case Stmt::ParenExprClass: { 949 const ParenExpr *Expr = cast<ParenExpr>(E); 950 return SemaCheckStringLiteral(Expr->getSubExpr(), TheCall, HasVAListArg, 951 format_idx, firstDataArg, isPrintf); 952 } 953 954 case Stmt::DeclRefExprClass: { 955 const DeclRefExpr *DR = cast<DeclRefExpr>(E); 956 957 // As an exception, do not flag errors for variables binding to 958 // const string literals. 959 if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) { 960 bool isConstant = false; 961 QualType T = DR->getType(); 962 963 if (const ArrayType *AT = Context.getAsArrayType(T)) { 964 isConstant = AT->getElementType().isConstant(Context); 965 } else if (const PointerType *PT = T->getAs<PointerType>()) { 966 isConstant = T.isConstant(Context) && 967 PT->getPointeeType().isConstant(Context); 968 } 969 970 if (isConstant) { 971 if (const Expr *Init = VD->getAnyInitializer()) 972 return SemaCheckStringLiteral(Init, TheCall, 973 HasVAListArg, format_idx, firstDataArg, 974 isPrintf); 975 } 976 977 // For vprintf* functions (i.e., HasVAListArg==true), we add a 978 // special check to see if the format string is a function parameter 979 // of the function calling the printf function. If the function 980 // has an attribute indicating it is a printf-like function, then we 981 // should suppress warnings concerning non-literals being used in a call 982 // to a vprintf function. For example: 983 // 984 // void 985 // logmessage(char const *fmt __attribute__ (format (printf, 1, 2)), ...){ 986 // va_list ap; 987 // va_start(ap, fmt); 988 // vprintf(fmt, ap); // Do NOT emit a warning about "fmt". 989 // ... 990 // 991 // 992 // FIXME: We don't have full attribute support yet, so just check to see 993 // if the argument is a DeclRefExpr that references a parameter. We'll 994 // add proper support for checking the attribute later. 995 if (HasVAListArg) 996 if (isa<ParmVarDecl>(VD)) 997 return true; 998 } 999 1000 return false; 1001 } 1002 1003 case Stmt::CallExprClass: { 1004 const CallExpr *CE = cast<CallExpr>(E); 1005 if (const ImplicitCastExpr *ICE 1006 = dyn_cast<ImplicitCastExpr>(CE->getCallee())) { 1007 if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(ICE->getSubExpr())) { 1008 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(DRE->getDecl())) { 1009 if (const FormatArgAttr *FA = FD->getAttr<FormatArgAttr>()) { 1010 unsigned ArgIndex = FA->getFormatIdx(); 1011 const Expr *Arg = CE->getArg(ArgIndex - 1); 1012 1013 return SemaCheckStringLiteral(Arg, TheCall, HasVAListArg, 1014 format_idx, firstDataArg, isPrintf); 1015 } 1016 } 1017 } 1018 } 1019 1020 return false; 1021 } 1022 case Stmt::ObjCStringLiteralClass: 1023 case Stmt::StringLiteralClass: { 1024 const StringLiteral *StrE = NULL; 1025 1026 if (const ObjCStringLiteral *ObjCFExpr = dyn_cast<ObjCStringLiteral>(E)) 1027 StrE = ObjCFExpr->getString(); 1028 else 1029 StrE = cast<StringLiteral>(E); 1030 1031 if (StrE) { 1032 CheckFormatString(StrE, E, TheCall, HasVAListArg, format_idx, 1033 firstDataArg, isPrintf); 1034 return true; 1035 } 1036 1037 return false; 1038 } 1039 1040 default: 1041 return false; 1042 } 1043} 1044 1045void 1046Sema::CheckNonNullArguments(const NonNullAttr *NonNull, 1047 const CallExpr *TheCall) { 1048 for (NonNullAttr::iterator i = NonNull->begin(), e = NonNull->end(); 1049 i != e; ++i) { 1050 const Expr *ArgExpr = TheCall->getArg(*i); 1051 if (ArgExpr->isNullPointerConstant(Context, 1052 Expr::NPC_ValueDependentIsNotNull)) 1053 Diag(TheCall->getCallee()->getLocStart(), diag::warn_null_arg) 1054 << ArgExpr->getSourceRange(); 1055 } 1056} 1057 1058/// CheckPrintfScanfArguments - Check calls to printf and scanf (and similar 1059/// functions) for correct use of format strings. 1060void 1061Sema::CheckPrintfScanfArguments(const CallExpr *TheCall, bool HasVAListArg, 1062 unsigned format_idx, unsigned firstDataArg, 1063 bool isPrintf) { 1064 1065 const Expr *Fn = TheCall->getCallee(); 1066 1067 // The way the format attribute works in GCC, the implicit this argument 1068 // of member functions is counted. However, it doesn't appear in our own 1069 // lists, so decrement format_idx in that case. 1070 if (isa<CXXMemberCallExpr>(TheCall)) { 1071 // Catch a format attribute mistakenly referring to the object argument. 1072 if (format_idx == 0) 1073 return; 1074 --format_idx; 1075 if(firstDataArg != 0) 1076 --firstDataArg; 1077 } 1078 1079 // CHECK: printf/scanf-like function is called with no format string. 1080 if (format_idx >= TheCall->getNumArgs()) { 1081 Diag(TheCall->getRParenLoc(), diag::warn_missing_format_string) 1082 << Fn->getSourceRange(); 1083 return; 1084 } 1085 1086 const Expr *OrigFormatExpr = TheCall->getArg(format_idx)->IgnoreParenCasts(); 1087 1088 // CHECK: format string is not a string literal. 1089 // 1090 // Dynamically generated format strings are difficult to 1091 // automatically vet at compile time. Requiring that format strings 1092 // are string literals: (1) permits the checking of format strings by 1093 // the compiler and thereby (2) can practically remove the source of 1094 // many format string exploits. 1095 1096 // Format string can be either ObjC string (e.g. @"%d") or 1097 // C string (e.g. "%d") 1098 // ObjC string uses the same format specifiers as C string, so we can use 1099 // the same format string checking logic for both ObjC and C strings. 1100 if (SemaCheckStringLiteral(OrigFormatExpr, TheCall, HasVAListArg, format_idx, 1101 firstDataArg, isPrintf)) 1102 return; // Literal format string found, check done! 1103 1104 // If there are no arguments specified, warn with -Wformat-security, otherwise 1105 // warn only with -Wformat-nonliteral. 1106 if (TheCall->getNumArgs() == format_idx+1) 1107 Diag(TheCall->getArg(format_idx)->getLocStart(), 1108 diag::warn_format_nonliteral_noargs) 1109 << OrigFormatExpr->getSourceRange(); 1110 else 1111 Diag(TheCall->getArg(format_idx)->getLocStart(), 1112 diag::warn_format_nonliteral) 1113 << OrigFormatExpr->getSourceRange(); 1114} 1115 1116namespace { 1117class CheckFormatHandler : public analyze_format_string::FormatStringHandler { 1118protected: 1119 Sema &S; 1120 const StringLiteral *FExpr; 1121 const Expr *OrigFormatExpr; 1122 const unsigned FirstDataArg; 1123 const unsigned NumDataArgs; 1124 const bool IsObjCLiteral; 1125 const char *Beg; // Start of format string. 1126 const bool HasVAListArg; 1127 const CallExpr *TheCall; 1128 unsigned FormatIdx; 1129 llvm::BitVector CoveredArgs; 1130 bool usesPositionalArgs; 1131 bool atFirstArg; 1132public: 1133 CheckFormatHandler(Sema &s, const StringLiteral *fexpr, 1134 const Expr *origFormatExpr, unsigned firstDataArg, 1135 unsigned numDataArgs, bool isObjCLiteral, 1136 const char *beg, bool hasVAListArg, 1137 const CallExpr *theCall, unsigned formatIdx) 1138 : S(s), FExpr(fexpr), OrigFormatExpr(origFormatExpr), 1139 FirstDataArg(firstDataArg), 1140 NumDataArgs(numDataArgs), 1141 IsObjCLiteral(isObjCLiteral), Beg(beg), 1142 HasVAListArg(hasVAListArg), 1143 TheCall(theCall), FormatIdx(formatIdx), 1144 usesPositionalArgs(false), atFirstArg(true) { 1145 CoveredArgs.resize(numDataArgs); 1146 CoveredArgs.reset(); 1147 } 1148 1149 void DoneProcessing(); 1150 1151 void HandleIncompleteSpecifier(const char *startSpecifier, 1152 unsigned specifierLen); 1153 1154 virtual void HandleInvalidPosition(const char *startSpecifier, 1155 unsigned specifierLen, 1156 analyze_format_string::PositionContext p); 1157 1158 virtual void HandleZeroPosition(const char *startPos, unsigned posLen); 1159 1160 void HandleNullChar(const char *nullCharacter); 1161 1162protected: 1163 SourceRange getFormatStringRange(); 1164 CharSourceRange getSpecifierRange(const char *startSpecifier, 1165 unsigned specifierLen); 1166 SourceLocation getLocationOfByte(const char *x); 1167 1168 const Expr *getDataArg(unsigned i) const; 1169}; 1170} 1171 1172SourceRange CheckFormatHandler::getFormatStringRange() { 1173 return OrigFormatExpr->getSourceRange(); 1174} 1175 1176CharSourceRange CheckFormatHandler:: 1177getSpecifierRange(const char *startSpecifier, unsigned specifierLen) { 1178 SourceLocation Start = getLocationOfByte(startSpecifier); 1179 SourceLocation End = getLocationOfByte(startSpecifier + specifierLen - 1); 1180 1181 // Advance the end SourceLocation by one due to half-open ranges. 1182 End = End.getFileLocWithOffset(1); 1183 1184 return CharSourceRange::getCharRange(Start, End); 1185} 1186 1187SourceLocation CheckFormatHandler::getLocationOfByte(const char *x) { 1188 return S.getLocationOfStringLiteralByte(FExpr, x - Beg); 1189} 1190 1191void CheckFormatHandler::HandleIncompleteSpecifier(const char *startSpecifier, 1192 unsigned specifierLen){ 1193 SourceLocation Loc = getLocationOfByte(startSpecifier); 1194 S.Diag(Loc, diag::warn_printf_incomplete_specifier) 1195 << getSpecifierRange(startSpecifier, specifierLen); 1196} 1197 1198void 1199CheckFormatHandler::HandleInvalidPosition(const char *startPos, unsigned posLen, 1200 analyze_format_string::PositionContext p) { 1201 SourceLocation Loc = getLocationOfByte(startPos); 1202 S.Diag(Loc, diag::warn_format_invalid_positional_specifier) 1203 << (unsigned) p << getSpecifierRange(startPos, posLen); 1204} 1205 1206void CheckFormatHandler::HandleZeroPosition(const char *startPos, 1207 unsigned posLen) { 1208 SourceLocation Loc = getLocationOfByte(startPos); 1209 S.Diag(Loc, diag::warn_format_zero_positional_specifier) 1210 << getSpecifierRange(startPos, posLen); 1211} 1212 1213void CheckFormatHandler::HandleNullChar(const char *nullCharacter) { 1214 // The presence of a null character is likely an error. 1215 S.Diag(getLocationOfByte(nullCharacter), 1216 diag::warn_printf_format_string_contains_null_char) 1217 << getFormatStringRange(); 1218} 1219 1220const Expr *CheckFormatHandler::getDataArg(unsigned i) const { 1221 return TheCall->getArg(FirstDataArg + i); 1222} 1223 1224void CheckFormatHandler::DoneProcessing() { 1225 // Does the number of data arguments exceed the number of 1226 // format conversions in the format string? 1227 if (!HasVAListArg) { 1228 // Find any arguments that weren't covered. 1229 CoveredArgs.flip(); 1230 signed notCoveredArg = CoveredArgs.find_first(); 1231 if (notCoveredArg >= 0) { 1232 assert((unsigned)notCoveredArg < NumDataArgs); 1233 S.Diag(getDataArg((unsigned) notCoveredArg)->getLocStart(), 1234 diag::warn_printf_data_arg_not_used) 1235 << getFormatStringRange(); 1236 } 1237 } 1238} 1239 1240//===--- CHECK: Printf format string checking ------------------------------===// 1241 1242namespace { 1243class CheckPrintfHandler : public CheckFormatHandler { 1244public: 1245 CheckPrintfHandler(Sema &s, const StringLiteral *fexpr, 1246 const Expr *origFormatExpr, unsigned firstDataArg, 1247 unsigned numDataArgs, bool isObjCLiteral, 1248 const char *beg, bool hasVAListArg, 1249 const CallExpr *theCall, unsigned formatIdx) 1250 : CheckFormatHandler(s, fexpr, origFormatExpr, firstDataArg, 1251 numDataArgs, isObjCLiteral, beg, hasVAListArg, 1252 theCall, formatIdx) {} 1253 1254 1255 bool HandleInvalidPrintfConversionSpecifier( 1256 const analyze_printf::PrintfSpecifier &FS, 1257 const char *startSpecifier, 1258 unsigned specifierLen); 1259 1260 bool HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier &FS, 1261 const char *startSpecifier, 1262 unsigned specifierLen); 1263 1264 bool HandleAmount(const analyze_format_string::OptionalAmount &Amt, unsigned k, 1265 const char *startSpecifier, unsigned specifierLen); 1266 void HandleInvalidAmount(const analyze_printf::PrintfSpecifier &FS, 1267 const analyze_printf::OptionalAmount &Amt, 1268 unsigned type, 1269 const char *startSpecifier, unsigned specifierLen); 1270 void HandleFlag(const analyze_printf::PrintfSpecifier &FS, 1271 const analyze_printf::OptionalFlag &flag, 1272 const char *startSpecifier, unsigned specifierLen); 1273 void HandleIgnoredFlag(const analyze_printf::PrintfSpecifier &FS, 1274 const analyze_printf::OptionalFlag &ignoredFlag, 1275 const analyze_printf::OptionalFlag &flag, 1276 const char *startSpecifier, unsigned specifierLen); 1277}; 1278} 1279 1280bool CheckPrintfHandler::HandleInvalidPrintfConversionSpecifier( 1281 const analyze_printf::PrintfSpecifier &FS, 1282 const char *startSpecifier, 1283 unsigned specifierLen) { 1284 1285 unsigned argIndex = FS.getArgIndex(); 1286 bool keepGoing = true; 1287 if (argIndex < NumDataArgs) { 1288 // Consider the argument coverered, even though the specifier doesn't 1289 // make sense. 1290 CoveredArgs.set(argIndex); 1291 } 1292 else { 1293 // If argIndex exceeds the number of data arguments we 1294 // don't issue a warning because that is just a cascade of warnings (and 1295 // they may have intended '%%' anyway). We don't want to continue processing 1296 // the format string after this point, however, as we will like just get 1297 // gibberish when trying to match arguments. 1298 keepGoing = false; 1299 } 1300 1301 const analyze_printf::ConversionSpecifier &CS = 1302 FS.getConversionSpecifier(); 1303 SourceLocation Loc = getLocationOfByte(CS.getStart()); 1304 S.Diag(Loc, diag::warn_printf_invalid_conversion) 1305 << llvm::StringRef(CS.getStart(), CS.getLength()) 1306 << getSpecifierRange(startSpecifier, specifierLen); 1307 1308 return keepGoing; 1309} 1310 1311bool CheckPrintfHandler::HandleAmount( 1312 const analyze_format_string::OptionalAmount &Amt, 1313 unsigned k, const char *startSpecifier, 1314 unsigned specifierLen) { 1315 1316 if (Amt.hasDataArgument()) { 1317 if (!HasVAListArg) { 1318 unsigned argIndex = Amt.getArgIndex(); 1319 if (argIndex >= NumDataArgs) { 1320 S.Diag(getLocationOfByte(Amt.getStart()), 1321 diag::warn_printf_asterisk_missing_arg) 1322 << k << getSpecifierRange(startSpecifier, specifierLen); 1323 // Don't do any more checking. We will just emit 1324 // spurious errors. 1325 return false; 1326 } 1327 1328 // Type check the data argument. It should be an 'int'. 1329 // Although not in conformance with C99, we also allow the argument to be 1330 // an 'unsigned int' as that is a reasonably safe case. GCC also 1331 // doesn't emit a warning for that case. 1332 CoveredArgs.set(argIndex); 1333 const Expr *Arg = getDataArg(argIndex); 1334 QualType T = Arg->getType(); 1335 1336 const analyze_printf::ArgTypeResult &ATR = Amt.getArgType(S.Context); 1337 assert(ATR.isValid()); 1338 1339 if (!ATR.matchesType(S.Context, T)) { 1340 S.Diag(getLocationOfByte(Amt.getStart()), 1341 diag::warn_printf_asterisk_wrong_type) 1342 << k 1343 << ATR.getRepresentativeType(S.Context) << T 1344 << getSpecifierRange(startSpecifier, specifierLen) 1345 << Arg->getSourceRange(); 1346 // Don't do any more checking. We will just emit 1347 // spurious errors. 1348 return false; 1349 } 1350 } 1351 } 1352 return true; 1353} 1354 1355void CheckPrintfHandler::HandleInvalidAmount( 1356 const analyze_printf::PrintfSpecifier &FS, 1357 const analyze_printf::OptionalAmount &Amt, 1358 unsigned type, 1359 const char *startSpecifier, 1360 unsigned specifierLen) { 1361 const analyze_printf::ConversionSpecifier &CS = FS.getConversionSpecifier(); 1362 switch (Amt.getHowSpecified()) { 1363 case analyze_printf::OptionalAmount::Constant: 1364 S.Diag(getLocationOfByte(Amt.getStart()), 1365 diag::warn_printf_nonsensical_optional_amount) 1366 << type 1367 << CS.toString() 1368 << getSpecifierRange(startSpecifier, specifierLen) 1369 << FixItHint::CreateRemoval(getSpecifierRange(Amt.getStart(), 1370 Amt.getConstantLength())); 1371 break; 1372 1373 default: 1374 S.Diag(getLocationOfByte(Amt.getStart()), 1375 diag::warn_printf_nonsensical_optional_amount) 1376 << type 1377 << CS.toString() 1378 << getSpecifierRange(startSpecifier, specifierLen); 1379 break; 1380 } 1381} 1382 1383void CheckPrintfHandler::HandleFlag(const analyze_printf::PrintfSpecifier &FS, 1384 const analyze_printf::OptionalFlag &flag, 1385 const char *startSpecifier, 1386 unsigned specifierLen) { 1387 // Warn about pointless flag with a fixit removal. 1388 const analyze_printf::ConversionSpecifier &CS = FS.getConversionSpecifier(); 1389 S.Diag(getLocationOfByte(flag.getPosition()), 1390 diag::warn_printf_nonsensical_flag) 1391 << flag.toString() << CS.toString() 1392 << getSpecifierRange(startSpecifier, specifierLen) 1393 << FixItHint::CreateRemoval(getSpecifierRange(flag.getPosition(), 1)); 1394} 1395 1396void CheckPrintfHandler::HandleIgnoredFlag( 1397 const analyze_printf::PrintfSpecifier &FS, 1398 const analyze_printf::OptionalFlag &ignoredFlag, 1399 const analyze_printf::OptionalFlag &flag, 1400 const char *startSpecifier, 1401 unsigned specifierLen) { 1402 // Warn about ignored flag with a fixit removal. 1403 S.Diag(getLocationOfByte(ignoredFlag.getPosition()), 1404 diag::warn_printf_ignored_flag) 1405 << ignoredFlag.toString() << flag.toString() 1406 << getSpecifierRange(startSpecifier, specifierLen) 1407 << FixItHint::CreateRemoval(getSpecifierRange( 1408 ignoredFlag.getPosition(), 1)); 1409} 1410 1411bool 1412CheckPrintfHandler::HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier 1413 &FS, 1414 const char *startSpecifier, 1415 unsigned specifierLen) { 1416 1417 using namespace analyze_printf; 1418 const ConversionSpecifier &CS = FS.getConversionSpecifier(); 1419 1420 if (atFirstArg) { 1421 atFirstArg = false; 1422 usesPositionalArgs = FS.usesPositionalArg(); 1423 } 1424 else if (usesPositionalArgs != FS.usesPositionalArg()) { 1425 // Cannot mix-and-match positional and non-positional arguments. 1426 S.Diag(getLocationOfByte(CS.getStart()), 1427 diag::warn_format_mix_positional_nonpositional_args) 1428 << getSpecifierRange(startSpecifier, specifierLen); 1429 return false; 1430 } 1431 1432 // First check if the field width, precision, and conversion specifier 1433 // have matching data arguments. 1434 if (!HandleAmount(FS.getFieldWidth(), /* field width */ 0, 1435 startSpecifier, specifierLen)) { 1436 return false; 1437 } 1438 1439 if (!HandleAmount(FS.getPrecision(), /* precision */ 1, 1440 startSpecifier, specifierLen)) { 1441 return false; 1442 } 1443 1444 if (!CS.consumesDataArgument()) { 1445 // FIXME: Technically specifying a precision or field width here 1446 // makes no sense. Worth issuing a warning at some point. 1447 return true; 1448 } 1449 1450 // Consume the argument. 1451 unsigned argIndex = FS.getArgIndex(); 1452 if (argIndex < NumDataArgs) { 1453 // The check to see if the argIndex is valid will come later. 1454 // We set the bit here because we may exit early from this 1455 // function if we encounter some other error. 1456 CoveredArgs.set(argIndex); 1457 } 1458 1459 // Check for using an Objective-C specific conversion specifier 1460 // in a non-ObjC literal. 1461 if (!IsObjCLiteral && CS.isObjCArg()) { 1462 return HandleInvalidPrintfConversionSpecifier(FS, startSpecifier, 1463 specifierLen); 1464 } 1465 1466 // Check for invalid use of field width 1467 if (!FS.hasValidFieldWidth()) { 1468 HandleInvalidAmount(FS, FS.getFieldWidth(), /* field width */ 0, 1469 startSpecifier, specifierLen); 1470 } 1471 1472 // Check for invalid use of precision 1473 if (!FS.hasValidPrecision()) { 1474 HandleInvalidAmount(FS, FS.getPrecision(), /* precision */ 1, 1475 startSpecifier, specifierLen); 1476 } 1477 1478 // Check each flag does not conflict with any other component. 1479 if (!FS.hasValidLeadingZeros()) 1480 HandleFlag(FS, FS.hasLeadingZeros(), startSpecifier, specifierLen); 1481 if (!FS.hasValidPlusPrefix()) 1482 HandleFlag(FS, FS.hasPlusPrefix(), startSpecifier, specifierLen); 1483 if (!FS.hasValidSpacePrefix()) 1484 HandleFlag(FS, FS.hasSpacePrefix(), startSpecifier, specifierLen); 1485 if (!FS.hasValidAlternativeForm()) 1486 HandleFlag(FS, FS.hasAlternativeForm(), startSpecifier, specifierLen); 1487 if (!FS.hasValidLeftJustified()) 1488 HandleFlag(FS, FS.isLeftJustified(), startSpecifier, specifierLen); 1489 1490 // Check that flags are not ignored by another flag 1491 if (FS.hasSpacePrefix() && FS.hasPlusPrefix()) // ' ' ignored by '+' 1492 HandleIgnoredFlag(FS, FS.hasSpacePrefix(), FS.hasPlusPrefix(), 1493 startSpecifier, specifierLen); 1494 if (FS.hasLeadingZeros() && FS.isLeftJustified()) // '0' ignored by '-' 1495 HandleIgnoredFlag(FS, FS.hasLeadingZeros(), FS.isLeftJustified(), 1496 startSpecifier, specifierLen); 1497 1498 // Check the length modifier is valid with the given conversion specifier. 1499 const LengthModifier &LM = FS.getLengthModifier(); 1500 if (!FS.hasValidLengthModifier()) 1501 S.Diag(getLocationOfByte(LM.getStart()), 1502 diag::warn_printf_nonsensical_length) 1503 << LM.toString() << CS.toString() 1504 << getSpecifierRange(startSpecifier, specifierLen) 1505 << FixItHint::CreateRemoval(getSpecifierRange(LM.getStart(), 1506 LM.getLength())); 1507 1508 // Are we using '%n'? 1509 if (CS.getKind() == ConversionSpecifier::OutIntPtrArg) { 1510 // Issue a warning about this being a possible security issue. 1511 S.Diag(getLocationOfByte(CS.getStart()), diag::warn_printf_write_back) 1512 << getSpecifierRange(startSpecifier, specifierLen); 1513 // Continue checking the other format specifiers. 1514 return true; 1515 } 1516 1517 // The remaining checks depend on the data arguments. 1518 if (HasVAListArg) 1519 return true; 1520 1521 if (argIndex >= NumDataArgs) { 1522 if (FS.usesPositionalArg()) { 1523 S.Diag(getLocationOfByte(CS.getStart()), 1524 diag::warn_printf_positional_arg_exceeds_data_args) 1525 << (argIndex+1) << NumDataArgs 1526 << getSpecifierRange(startSpecifier, specifierLen); 1527 } 1528 else { 1529 S.Diag(getLocationOfByte(CS.getStart()), 1530 diag::warn_printf_insufficient_data_args) 1531 << getSpecifierRange(startSpecifier, specifierLen); 1532 } 1533 1534 // Don't do any more checking. 1535 return false; 1536 } 1537 1538 // Now type check the data expression that matches the 1539 // format specifier. 1540 const Expr *Ex = getDataArg(argIndex); 1541 const analyze_printf::ArgTypeResult &ATR = FS.getArgType(S.Context); 1542 if (ATR.isValid() && !ATR.matchesType(S.Context, Ex->getType())) { 1543 // Check if we didn't match because of an implicit cast from a 'char' 1544 // or 'short' to an 'int'. This is done because printf is a varargs 1545 // function. 1546 if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Ex)) 1547 if (ICE->getType() == S.Context.IntTy) 1548 if (ATR.matchesType(S.Context, ICE->getSubExpr()->getType())) 1549 return true; 1550 1551 // We may be able to offer a FixItHint if it is a supported type. 1552 PrintfSpecifier fixedFS = FS; 1553 bool success = fixedFS.fixType(Ex->getType()); 1554 1555 if (success) { 1556 // Get the fix string from the fixed format specifier 1557 llvm::SmallString<128> buf; 1558 llvm::raw_svector_ostream os(buf); 1559 fixedFS.toString(os); 1560 1561 S.Diag(getLocationOfByte(CS.getStart()), 1562 diag::warn_printf_conversion_argument_type_mismatch) 1563 << ATR.getRepresentativeType(S.Context) << Ex->getType() 1564 << getSpecifierRange(startSpecifier, specifierLen) 1565 << Ex->getSourceRange() 1566 << FixItHint::CreateReplacement( 1567 getSpecifierRange(startSpecifier, specifierLen), 1568 os.str()); 1569 } 1570 else { 1571 S.Diag(getLocationOfByte(CS.getStart()), 1572 diag::warn_printf_conversion_argument_type_mismatch) 1573 << ATR.getRepresentativeType(S.Context) << Ex->getType() 1574 << getSpecifierRange(startSpecifier, specifierLen) 1575 << Ex->getSourceRange(); 1576 } 1577 } 1578 1579 return true; 1580} 1581 1582//===--- CHECK: Scanf format string checking ------------------------------===// 1583 1584namespace { 1585class CheckScanfHandler : public CheckFormatHandler { 1586public: 1587 CheckScanfHandler(Sema &s, const StringLiteral *fexpr, 1588 const Expr *origFormatExpr, unsigned firstDataArg, 1589 unsigned numDataArgs, bool isObjCLiteral, 1590 const char *beg, bool hasVAListArg, 1591 const CallExpr *theCall, unsigned formatIdx) 1592 : CheckFormatHandler(s, fexpr, origFormatExpr, firstDataArg, 1593 numDataArgs, isObjCLiteral, beg, hasVAListArg, 1594 theCall, formatIdx) {} 1595 1596 bool HandleScanfSpecifier(const analyze_scanf::ScanfSpecifier &FS, 1597 const char *startSpecifier, 1598 unsigned specifierLen); 1599 1600 void HandleIncompleteScanList(const char *start, const char *end); 1601}; 1602} 1603 1604void CheckScanfHandler::HandleIncompleteScanList(const char *start, 1605 const char *end) { 1606 S.Diag(getLocationOfByte(end), diag::warn_scanf_scanlist_incomplete) 1607 << getSpecifierRange(start, end - start); 1608} 1609 1610bool CheckScanfHandler::HandleScanfSpecifier( 1611 const analyze_scanf::ScanfSpecifier &FS, 1612 const char *startSpecifier, 1613 unsigned specifierLen) { 1614 1615 using namespace analyze_scanf; 1616 using namespace analyze_format_string; 1617 1618 const ConversionSpecifier &CS = FS.getConversionSpecifier(); 1619 1620 // FIXME: Handle case where '%' and '*' don't consume an argument. 1621 // This needs to be done for the printf case as well. 1622 if (atFirstArg) { 1623 atFirstArg = false; 1624 usesPositionalArgs = FS.usesPositionalArg(); 1625 } 1626 else if (usesPositionalArgs != FS.usesPositionalArg()) { 1627 // Cannot mix-and-match positional and non-positional arguments. 1628 S.Diag(getLocationOfByte(CS.getStart()), 1629 diag::warn_format_mix_positional_nonpositional_args) 1630 << getSpecifierRange(startSpecifier, specifierLen); 1631 return false; 1632 } 1633 1634 // Check if the field with is non-zero. 1635 const OptionalAmount &Amt = FS.getFieldWidth(); 1636 if (Amt.getHowSpecified() == OptionalAmount::Constant) { 1637 if (Amt.getConstantAmount() == 0) { 1638 const CharSourceRange &R = getSpecifierRange(Amt.getStart(), 1639 Amt.getConstantLength()); 1640 S.Diag(getLocationOfByte(Amt.getStart()), 1641 diag::warn_scanf_nonzero_width) 1642 << R << FixItHint::CreateRemoval(R); 1643 } 1644 } 1645 1646 if (!FS.consumesDataArgument()) { 1647 // FIXME: Technically specifying a precision or field width here 1648 // makes no sense. Worth issuing a warning at some point. 1649 return true; 1650 } 1651 1652 // Consume the argument. 1653 unsigned argIndex = FS.getArgIndex(); 1654 if (argIndex < NumDataArgs) { 1655 // The check to see if the argIndex is valid will come later. 1656 // We set the bit here because we may exit early from this 1657 // function if we encounter some other error. 1658 CoveredArgs.set(argIndex); 1659 } 1660 1661 // FIXME: Check that the length modifier is valid with the given 1662 // conversion specifier. 1663 1664 // The remaining checks depend on the data arguments. 1665 if (HasVAListArg) 1666 return true; 1667 1668 if (argIndex >= NumDataArgs) { 1669 if (FS.usesPositionalArg()) { 1670 S.Diag(getLocationOfByte(CS.getStart()), 1671 diag::warn_printf_positional_arg_exceeds_data_args) 1672 << (argIndex+1) << NumDataArgs 1673 << getSpecifierRange(startSpecifier, specifierLen); 1674 } 1675 else { 1676 S.Diag(getLocationOfByte(CS.getStart()), 1677 diag::warn_printf_insufficient_data_args) 1678 << getSpecifierRange(startSpecifier, specifierLen); 1679 } 1680 1681 // Don't do any more checking. 1682 return false; 1683 } 1684 1685 // FIXME: Check that the argument type matches the format specifier. 1686 1687 return true; 1688} 1689 1690void Sema::CheckFormatString(const StringLiteral *FExpr, 1691 const Expr *OrigFormatExpr, 1692 const CallExpr *TheCall, bool HasVAListArg, 1693 unsigned format_idx, unsigned firstDataArg, 1694 bool isPrintf) { 1695 1696 // CHECK: is the format string a wide literal? 1697 if (FExpr->isWide()) { 1698 Diag(FExpr->getLocStart(), 1699 diag::warn_format_string_is_wide_literal) 1700 << OrigFormatExpr->getSourceRange(); 1701 return; 1702 } 1703 1704 // Str - The format string. NOTE: this is NOT null-terminated! 1705 const char *Str = FExpr->getStrData(); 1706 1707 // CHECK: empty format string? 1708 unsigned StrLen = FExpr->getByteLength(); 1709 1710 if (StrLen == 0) { 1711 Diag(FExpr->getLocStart(), diag::warn_empty_format_string) 1712 << OrigFormatExpr->getSourceRange(); 1713 return; 1714 } 1715 1716 if (isPrintf) { 1717 CheckPrintfHandler H(*this, FExpr, OrigFormatExpr, firstDataArg, 1718 TheCall->getNumArgs() - firstDataArg, 1719 isa<ObjCStringLiteral>(OrigFormatExpr), Str, 1720 HasVAListArg, TheCall, format_idx); 1721 1722 if (!analyze_format_string::ParsePrintfString(H, Str, Str + StrLen)) 1723 H.DoneProcessing(); 1724 } 1725 else { 1726 CheckScanfHandler H(*this, FExpr, OrigFormatExpr, firstDataArg, 1727 TheCall->getNumArgs() - firstDataArg, 1728 isa<ObjCStringLiteral>(OrigFormatExpr), Str, 1729 HasVAListArg, TheCall, format_idx); 1730 1731 if (!analyze_format_string::ParseScanfString(H, Str, Str + StrLen)) 1732 H.DoneProcessing(); 1733 } 1734} 1735 1736//===--- CHECK: Return Address of Stack Variable --------------------------===// 1737 1738static DeclRefExpr* EvalVal(Expr *E); 1739static DeclRefExpr* EvalAddr(Expr* E); 1740 1741/// CheckReturnStackAddr - Check if a return statement returns the address 1742/// of a stack variable. 1743void 1744Sema::CheckReturnStackAddr(Expr *RetValExp, QualType lhsType, 1745 SourceLocation ReturnLoc) { 1746 1747 // Perform checking for returned stack addresses. 1748 if (lhsType->isPointerType() || lhsType->isBlockPointerType()) { 1749 if (DeclRefExpr *DR = EvalAddr(RetValExp)) 1750 Diag(DR->getLocStart(), diag::warn_ret_stack_addr) 1751 << DR->getDecl()->getDeclName() << RetValExp->getSourceRange(); 1752 1753 // Skip over implicit cast expressions when checking for block expressions. 1754 RetValExp = RetValExp->IgnoreParenCasts(); 1755 1756 if (BlockExpr *C = dyn_cast<BlockExpr>(RetValExp)) 1757 if (C->hasBlockDeclRefExprs()) 1758 Diag(C->getLocStart(), diag::err_ret_local_block) 1759 << C->getSourceRange(); 1760 1761 if (AddrLabelExpr *ALE = dyn_cast<AddrLabelExpr>(RetValExp)) 1762 Diag(ALE->getLocStart(), diag::warn_ret_addr_label) 1763 << ALE->getSourceRange(); 1764 1765 } else if (lhsType->isReferenceType()) { 1766 // Perform checking for stack values returned by reference. 1767 // Check for a reference to the stack 1768 if (DeclRefExpr *DR = EvalVal(RetValExp)) 1769 Diag(DR->getLocStart(), diag::warn_ret_stack_ref) 1770 << DR->getDecl()->getDeclName() << RetValExp->getSourceRange(); 1771 } 1772} 1773 1774/// EvalAddr - EvalAddr and EvalVal are mutually recursive functions that 1775/// check if the expression in a return statement evaluates to an address 1776/// to a location on the stack. The recursion is used to traverse the 1777/// AST of the return expression, with recursion backtracking when we 1778/// encounter a subexpression that (1) clearly does not lead to the address 1779/// of a stack variable or (2) is something we cannot determine leads to 1780/// the address of a stack variable based on such local checking. 1781/// 1782/// EvalAddr processes expressions that are pointers that are used as 1783/// references (and not L-values). EvalVal handles all other values. 1784/// At the base case of the recursion is a check for a DeclRefExpr* in 1785/// the refers to a stack variable. 1786/// 1787/// This implementation handles: 1788/// 1789/// * pointer-to-pointer casts 1790/// * implicit conversions from array references to pointers 1791/// * taking the address of fields 1792/// * arbitrary interplay between "&" and "*" operators 1793/// * pointer arithmetic from an address of a stack variable 1794/// * taking the address of an array element where the array is on the stack 1795static DeclRefExpr* EvalAddr(Expr *E) { 1796 // We should only be called for evaluating pointer expressions. 1797 assert((E->getType()->isAnyPointerType() || 1798 E->getType()->isBlockPointerType() || 1799 E->getType()->isObjCQualifiedIdType()) && 1800 "EvalAddr only works on pointers"); 1801 1802 // Our "symbolic interpreter" is just a dispatch off the currently 1803 // viewed AST node. We then recursively traverse the AST by calling 1804 // EvalAddr and EvalVal appropriately. 1805 switch (E->getStmtClass()) { 1806 case Stmt::ParenExprClass: 1807 // Ignore parentheses. 1808 return EvalAddr(cast<ParenExpr>(E)->getSubExpr()); 1809 1810 case Stmt::UnaryOperatorClass: { 1811 // The only unary operator that make sense to handle here 1812 // is AddrOf. All others don't make sense as pointers. 1813 UnaryOperator *U = cast<UnaryOperator>(E); 1814 1815 if (U->getOpcode() == UnaryOperator::AddrOf) 1816 return EvalVal(U->getSubExpr()); 1817 else 1818 return NULL; 1819 } 1820 1821 case Stmt::BinaryOperatorClass: { 1822 // Handle pointer arithmetic. All other binary operators are not valid 1823 // in this context. 1824 BinaryOperator *B = cast<BinaryOperator>(E); 1825 BinaryOperator::Opcode op = B->getOpcode(); 1826 1827 if (op != BinaryOperator::Add && op != BinaryOperator::Sub) 1828 return NULL; 1829 1830 Expr *Base = B->getLHS(); 1831 1832 // Determine which argument is the real pointer base. It could be 1833 // the RHS argument instead of the LHS. 1834 if (!Base->getType()->isPointerType()) Base = B->getRHS(); 1835 1836 assert (Base->getType()->isPointerType()); 1837 return EvalAddr(Base); 1838 } 1839 1840 // For conditional operators we need to see if either the LHS or RHS are 1841 // valid DeclRefExpr*s. If one of them is valid, we return it. 1842 case Stmt::ConditionalOperatorClass: { 1843 ConditionalOperator *C = cast<ConditionalOperator>(E); 1844 1845 // Handle the GNU extension for missing LHS. 1846 if (Expr *lhsExpr = C->getLHS()) 1847 if (DeclRefExpr* LHS = EvalAddr(lhsExpr)) 1848 return LHS; 1849 1850 return EvalAddr(C->getRHS()); 1851 } 1852 1853 // For casts, we need to handle conversions from arrays to 1854 // pointer values, and pointer-to-pointer conversions. 1855 case Stmt::ImplicitCastExprClass: 1856 case Stmt::CStyleCastExprClass: 1857 case Stmt::CXXFunctionalCastExprClass: { 1858 Expr* SubExpr = cast<CastExpr>(E)->getSubExpr(); 1859 QualType T = SubExpr->getType(); 1860 1861 if (SubExpr->getType()->isPointerType() || 1862 SubExpr->getType()->isBlockPointerType() || 1863 SubExpr->getType()->isObjCQualifiedIdType()) 1864 return EvalAddr(SubExpr); 1865 else if (T->isArrayType()) 1866 return EvalVal(SubExpr); 1867 else 1868 return 0; 1869 } 1870 1871 // C++ casts. For dynamic casts, static casts, and const casts, we 1872 // are always converting from a pointer-to-pointer, so we just blow 1873 // through the cast. In the case the dynamic cast doesn't fail (and 1874 // return NULL), we take the conservative route and report cases 1875 // where we return the address of a stack variable. For Reinterpre 1876 // FIXME: The comment about is wrong; we're not always converting 1877 // from pointer to pointer. I'm guessing that this code should also 1878 // handle references to objects. 1879 case Stmt::CXXStaticCastExprClass: 1880 case Stmt::CXXDynamicCastExprClass: 1881 case Stmt::CXXConstCastExprClass: 1882 case Stmt::CXXReinterpretCastExprClass: { 1883 Expr *S = cast<CXXNamedCastExpr>(E)->getSubExpr(); 1884 if (S->getType()->isPointerType() || S->getType()->isBlockPointerType()) 1885 return EvalAddr(S); 1886 else 1887 return NULL; 1888 } 1889 1890 // Everything else: we simply don't reason about them. 1891 default: 1892 return NULL; 1893 } 1894} 1895 1896 1897/// EvalVal - This function is complements EvalAddr in the mutual recursion. 1898/// See the comments for EvalAddr for more details. 1899static DeclRefExpr* EvalVal(Expr *E) { 1900 1901 // We should only be called for evaluating non-pointer expressions, or 1902 // expressions with a pointer type that are not used as references but instead 1903 // are l-values (e.g., DeclRefExpr with a pointer type). 1904 1905 // Our "symbolic interpreter" is just a dispatch off the currently 1906 // viewed AST node. We then recursively traverse the AST by calling 1907 // EvalAddr and EvalVal appropriately. 1908 switch (E->getStmtClass()) { 1909 case Stmt::DeclRefExprClass: { 1910 // DeclRefExpr: the base case. When we hit a DeclRefExpr we are looking 1911 // at code that refers to a variable's name. We check if it has local 1912 // storage within the function, and if so, return the expression. 1913 DeclRefExpr *DR = cast<DeclRefExpr>(E); 1914 1915 if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl())) 1916 if (V->hasLocalStorage() && !V->getType()->isReferenceType()) return DR; 1917 1918 return NULL; 1919 } 1920 1921 case Stmt::ParenExprClass: 1922 // Ignore parentheses. 1923 return EvalVal(cast<ParenExpr>(E)->getSubExpr()); 1924 1925 case Stmt::UnaryOperatorClass: { 1926 // The only unary operator that make sense to handle here 1927 // is Deref. All others don't resolve to a "name." This includes 1928 // handling all sorts of rvalues passed to a unary operator. 1929 UnaryOperator *U = cast<UnaryOperator>(E); 1930 1931 if (U->getOpcode() == UnaryOperator::Deref) 1932 return EvalAddr(U->getSubExpr()); 1933 1934 return NULL; 1935 } 1936 1937 case Stmt::ArraySubscriptExprClass: { 1938 // Array subscripts are potential references to data on the stack. We 1939 // retrieve the DeclRefExpr* for the array variable if it indeed 1940 // has local storage. 1941 return EvalAddr(cast<ArraySubscriptExpr>(E)->getBase()); 1942 } 1943 1944 case Stmt::ConditionalOperatorClass: { 1945 // For conditional operators we need to see if either the LHS or RHS are 1946 // non-NULL DeclRefExpr's. If one is non-NULL, we return it. 1947 ConditionalOperator *C = cast<ConditionalOperator>(E); 1948 1949 // Handle the GNU extension for missing LHS. 1950 if (Expr *lhsExpr = C->getLHS()) 1951 if (DeclRefExpr *LHS = EvalVal(lhsExpr)) 1952 return LHS; 1953 1954 return EvalVal(C->getRHS()); 1955 } 1956 1957 // Accesses to members are potential references to data on the stack. 1958 case Stmt::MemberExprClass: { 1959 MemberExpr *M = cast<MemberExpr>(E); 1960 1961 // Check for indirect access. We only want direct field accesses. 1962 if (!M->isArrow()) 1963 return EvalVal(M->getBase()); 1964 else 1965 return NULL; 1966 } 1967 1968 // Everything else: we simply don't reason about them. 1969 default: 1970 return NULL; 1971 } 1972} 1973 1974//===--- CHECK: Floating-Point comparisons (-Wfloat-equal) ---------------===// 1975 1976/// Check for comparisons of floating point operands using != and ==. 1977/// Issue a warning if these are no self-comparisons, as they are not likely 1978/// to do what the programmer intended. 1979void Sema::CheckFloatComparison(SourceLocation loc, Expr* lex, Expr *rex) { 1980 bool EmitWarning = true; 1981 1982 Expr* LeftExprSansParen = lex->IgnoreParens(); 1983 Expr* RightExprSansParen = rex->IgnoreParens(); 1984 1985 // Special case: check for x == x (which is OK). 1986 // Do not emit warnings for such cases. 1987 if (DeclRefExpr* DRL = dyn_cast<DeclRefExpr>(LeftExprSansParen)) 1988 if (DeclRefExpr* DRR = dyn_cast<DeclRefExpr>(RightExprSansParen)) 1989 if (DRL->getDecl() == DRR->getDecl()) 1990 EmitWarning = false; 1991 1992 1993 // Special case: check for comparisons against literals that can be exactly 1994 // represented by APFloat. In such cases, do not emit a warning. This 1995 // is a heuristic: often comparison against such literals are used to 1996 // detect if a value in a variable has not changed. This clearly can 1997 // lead to false negatives. 1998 if (EmitWarning) { 1999 if (FloatingLiteral* FLL = dyn_cast<FloatingLiteral>(LeftExprSansParen)) { 2000 if (FLL->isExact()) 2001 EmitWarning = false; 2002 } else 2003 if (FloatingLiteral* FLR = dyn_cast<FloatingLiteral>(RightExprSansParen)){ 2004 if (FLR->isExact()) 2005 EmitWarning = false; 2006 } 2007 } 2008 2009 // Check for comparisons with builtin types. 2010 if (EmitWarning) 2011 if (CallExpr* CL = dyn_cast<CallExpr>(LeftExprSansParen)) 2012 if (CL->isBuiltinCall(Context)) 2013 EmitWarning = false; 2014 2015 if (EmitWarning) 2016 if (CallExpr* CR = dyn_cast<CallExpr>(RightExprSansParen)) 2017 if (CR->isBuiltinCall(Context)) 2018 EmitWarning = false; 2019 2020 // Emit the diagnostic. 2021 if (EmitWarning) 2022 Diag(loc, diag::warn_floatingpoint_eq) 2023 << lex->getSourceRange() << rex->getSourceRange(); 2024} 2025 2026//===--- CHECK: Integer mixed-sign comparisons (-Wsign-compare) --------===// 2027//===--- CHECK: Lossy implicit conversions (-Wconversion) --------------===// 2028 2029namespace { 2030 2031/// Structure recording the 'active' range of an integer-valued 2032/// expression. 2033struct IntRange { 2034 /// The number of bits active in the int. 2035 unsigned Width; 2036 2037 /// True if the int is known not to have negative values. 2038 bool NonNegative; 2039 2040 IntRange() {} 2041 IntRange(unsigned Width, bool NonNegative) 2042 : Width(Width), NonNegative(NonNegative) 2043 {} 2044 2045 // Returns the range of the bool type. 2046 static IntRange forBoolType() { 2047 return IntRange(1, true); 2048 } 2049 2050 // Returns the range of an integral type. 2051 static IntRange forType(ASTContext &C, QualType T) { 2052 return forCanonicalType(C, T->getCanonicalTypeInternal().getTypePtr()); 2053 } 2054 2055 // Returns the range of an integeral type based on its canonical 2056 // representation. 2057 static IntRange forCanonicalType(ASTContext &C, const Type *T) { 2058 assert(T->isCanonicalUnqualified()); 2059 2060 if (const VectorType *VT = dyn_cast<VectorType>(T)) 2061 T = VT->getElementType().getTypePtr(); 2062 if (const ComplexType *CT = dyn_cast<ComplexType>(T)) 2063 T = CT->getElementType().getTypePtr(); 2064 2065 if (const EnumType *ET = dyn_cast<EnumType>(T)) { 2066 EnumDecl *Enum = ET->getDecl(); 2067 unsigned NumPositive = Enum->getNumPositiveBits(); 2068 unsigned NumNegative = Enum->getNumNegativeBits(); 2069 2070 return IntRange(std::max(NumPositive, NumNegative), NumNegative == 0); 2071 } 2072 2073 const BuiltinType *BT = cast<BuiltinType>(T); 2074 assert(BT->isInteger()); 2075 2076 return IntRange(C.getIntWidth(QualType(T, 0)), BT->isUnsignedInteger()); 2077 } 2078 2079 // Returns the supremum of two ranges: i.e. their conservative merge. 2080 static IntRange join(IntRange L, IntRange R) { 2081 return IntRange(std::max(L.Width, R.Width), 2082 L.NonNegative && R.NonNegative); 2083 } 2084 2085 // Returns the infinum of two ranges: i.e. their aggressive merge. 2086 static IntRange meet(IntRange L, IntRange R) { 2087 return IntRange(std::min(L.Width, R.Width), 2088 L.NonNegative || R.NonNegative); 2089 } 2090}; 2091 2092IntRange GetValueRange(ASTContext &C, llvm::APSInt &value, unsigned MaxWidth) { 2093 if (value.isSigned() && value.isNegative()) 2094 return IntRange(value.getMinSignedBits(), false); 2095 2096 if (value.getBitWidth() > MaxWidth) 2097 value.trunc(MaxWidth); 2098 2099 // isNonNegative() just checks the sign bit without considering 2100 // signedness. 2101 return IntRange(value.getActiveBits(), true); 2102} 2103 2104IntRange GetValueRange(ASTContext &C, APValue &result, QualType Ty, 2105 unsigned MaxWidth) { 2106 if (result.isInt()) 2107 return GetValueRange(C, result.getInt(), MaxWidth); 2108 2109 if (result.isVector()) { 2110 IntRange R = GetValueRange(C, result.getVectorElt(0), Ty, MaxWidth); 2111 for (unsigned i = 1, e = result.getVectorLength(); i != e; ++i) { 2112 IntRange El = GetValueRange(C, result.getVectorElt(i), Ty, MaxWidth); 2113 R = IntRange::join(R, El); 2114 } 2115 return R; 2116 } 2117 2118 if (result.isComplexInt()) { 2119 IntRange R = GetValueRange(C, result.getComplexIntReal(), MaxWidth); 2120 IntRange I = GetValueRange(C, result.getComplexIntImag(), MaxWidth); 2121 return IntRange::join(R, I); 2122 } 2123 2124 // This can happen with lossless casts to intptr_t of "based" lvalues. 2125 // Assume it might use arbitrary bits. 2126 // FIXME: The only reason we need to pass the type in here is to get 2127 // the sign right on this one case. It would be nice if APValue 2128 // preserved this. 2129 assert(result.isLValue()); 2130 return IntRange(MaxWidth, Ty->isUnsignedIntegerType()); 2131} 2132 2133/// Pseudo-evaluate the given integer expression, estimating the 2134/// range of values it might take. 2135/// 2136/// \param MaxWidth - the width to which the value will be truncated 2137IntRange GetExprRange(ASTContext &C, Expr *E, unsigned MaxWidth) { 2138 E = E->IgnoreParens(); 2139 2140 // Try a full evaluation first. 2141 Expr::EvalResult result; 2142 if (E->Evaluate(result, C)) 2143 return GetValueRange(C, result.Val, E->getType(), MaxWidth); 2144 2145 // I think we only want to look through implicit casts here; if the 2146 // user has an explicit widening cast, we should treat the value as 2147 // being of the new, wider type. 2148 if (ImplicitCastExpr *CE = dyn_cast<ImplicitCastExpr>(E)) { 2149 if (CE->getCastKind() == CastExpr::CK_NoOp) 2150 return GetExprRange(C, CE->getSubExpr(), MaxWidth); 2151 2152 IntRange OutputTypeRange = IntRange::forType(C, CE->getType()); 2153 2154 bool isIntegerCast = (CE->getCastKind() == CastExpr::CK_IntegralCast); 2155 if (!isIntegerCast && CE->getCastKind() == CastExpr::CK_Unknown) 2156 isIntegerCast = CE->getSubExpr()->getType()->isIntegerType(); 2157 2158 // Assume that non-integer casts can span the full range of the type. 2159 if (!isIntegerCast) 2160 return OutputTypeRange; 2161 2162 IntRange SubRange 2163 = GetExprRange(C, CE->getSubExpr(), 2164 std::min(MaxWidth, OutputTypeRange.Width)); 2165 2166 // Bail out if the subexpr's range is as wide as the cast type. 2167 if (SubRange.Width >= OutputTypeRange.Width) 2168 return OutputTypeRange; 2169 2170 // Otherwise, we take the smaller width, and we're non-negative if 2171 // either the output type or the subexpr is. 2172 return IntRange(SubRange.Width, 2173 SubRange.NonNegative || OutputTypeRange.NonNegative); 2174 } 2175 2176 if (ConditionalOperator *CO = dyn_cast<ConditionalOperator>(E)) { 2177 // If we can fold the condition, just take that operand. 2178 bool CondResult; 2179 if (CO->getCond()->EvaluateAsBooleanCondition(CondResult, C)) 2180 return GetExprRange(C, CondResult ? CO->getTrueExpr() 2181 : CO->getFalseExpr(), 2182 MaxWidth); 2183 2184 // Otherwise, conservatively merge. 2185 IntRange L = GetExprRange(C, CO->getTrueExpr(), MaxWidth); 2186 IntRange R = GetExprRange(C, CO->getFalseExpr(), MaxWidth); 2187 return IntRange::join(L, R); 2188 } 2189 2190 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) { 2191 switch (BO->getOpcode()) { 2192 2193 // Boolean-valued operations are single-bit and positive. 2194 case BinaryOperator::LAnd: 2195 case BinaryOperator::LOr: 2196 case BinaryOperator::LT: 2197 case BinaryOperator::GT: 2198 case BinaryOperator::LE: 2199 case BinaryOperator::GE: 2200 case BinaryOperator::EQ: 2201 case BinaryOperator::NE: 2202 return IntRange::forBoolType(); 2203 2204 // The type of these compound assignments is the type of the LHS, 2205 // so the RHS is not necessarily an integer. 2206 case BinaryOperator::MulAssign: 2207 case BinaryOperator::DivAssign: 2208 case BinaryOperator::RemAssign: 2209 case BinaryOperator::AddAssign: 2210 case BinaryOperator::SubAssign: 2211 return IntRange::forType(C, E->getType()); 2212 2213 // Operations with opaque sources are black-listed. 2214 case BinaryOperator::PtrMemD: 2215 case BinaryOperator::PtrMemI: 2216 return IntRange::forType(C, E->getType()); 2217 2218 // Bitwise-and uses the *infinum* of the two source ranges. 2219 case BinaryOperator::And: 2220 case BinaryOperator::AndAssign: 2221 return IntRange::meet(GetExprRange(C, BO->getLHS(), MaxWidth), 2222 GetExprRange(C, BO->getRHS(), MaxWidth)); 2223 2224 // Left shift gets black-listed based on a judgement call. 2225 case BinaryOperator::Shl: 2226 // ...except that we want to treat '1 << (blah)' as logically 2227 // positive. It's an important idiom. 2228 if (IntegerLiteral *I 2229 = dyn_cast<IntegerLiteral>(BO->getLHS()->IgnoreParenCasts())) { 2230 if (I->getValue() == 1) { 2231 IntRange R = IntRange::forType(C, E->getType()); 2232 return IntRange(R.Width, /*NonNegative*/ true); 2233 } 2234 } 2235 // fallthrough 2236 2237 case BinaryOperator::ShlAssign: 2238 return IntRange::forType(C, E->getType()); 2239 2240 // Right shift by a constant can narrow its left argument. 2241 case BinaryOperator::Shr: 2242 case BinaryOperator::ShrAssign: { 2243 IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth); 2244 2245 // If the shift amount is a positive constant, drop the width by 2246 // that much. 2247 llvm::APSInt shift; 2248 if (BO->getRHS()->isIntegerConstantExpr(shift, C) && 2249 shift.isNonNegative()) { 2250 unsigned zext = shift.getZExtValue(); 2251 if (zext >= L.Width) 2252 L.Width = (L.NonNegative ? 0 : 1); 2253 else 2254 L.Width -= zext; 2255 } 2256 2257 return L; 2258 } 2259 2260 // Comma acts as its right operand. 2261 case BinaryOperator::Comma: 2262 return GetExprRange(C, BO->getRHS(), MaxWidth); 2263 2264 // Black-list pointer subtractions. 2265 case BinaryOperator::Sub: 2266 if (BO->getLHS()->getType()->isPointerType()) 2267 return IntRange::forType(C, E->getType()); 2268 // fallthrough 2269 2270 default: 2271 break; 2272 } 2273 2274 // Treat every other operator as if it were closed on the 2275 // narrowest type that encompasses both operands. 2276 IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth); 2277 IntRange R = GetExprRange(C, BO->getRHS(), MaxWidth); 2278 return IntRange::join(L, R); 2279 } 2280 2281 if (UnaryOperator *UO = dyn_cast<UnaryOperator>(E)) { 2282 switch (UO->getOpcode()) { 2283 // Boolean-valued operations are white-listed. 2284 case UnaryOperator::LNot: 2285 return IntRange::forBoolType(); 2286 2287 // Operations with opaque sources are black-listed. 2288 case UnaryOperator::Deref: 2289 case UnaryOperator::AddrOf: // should be impossible 2290 case UnaryOperator::OffsetOf: 2291 return IntRange::forType(C, E->getType()); 2292 2293 default: 2294 return GetExprRange(C, UO->getSubExpr(), MaxWidth); 2295 } 2296 } 2297 2298 if (dyn_cast<OffsetOfExpr>(E)) { 2299 IntRange::forType(C, E->getType()); 2300 } 2301 2302 FieldDecl *BitField = E->getBitField(); 2303 if (BitField) { 2304 llvm::APSInt BitWidthAP = BitField->getBitWidth()->EvaluateAsInt(C); 2305 unsigned BitWidth = BitWidthAP.getZExtValue(); 2306 2307 return IntRange(BitWidth, BitField->getType()->isUnsignedIntegerType()); 2308 } 2309 2310 return IntRange::forType(C, E->getType()); 2311} 2312 2313IntRange GetExprRange(ASTContext &C, Expr *E) { 2314 return GetExprRange(C, E, C.getIntWidth(E->getType())); 2315} 2316 2317/// Checks whether the given value, which currently has the given 2318/// source semantics, has the same value when coerced through the 2319/// target semantics. 2320bool IsSameFloatAfterCast(const llvm::APFloat &value, 2321 const llvm::fltSemantics &Src, 2322 const llvm::fltSemantics &Tgt) { 2323 llvm::APFloat truncated = value; 2324 2325 bool ignored; 2326 truncated.convert(Src, llvm::APFloat::rmNearestTiesToEven, &ignored); 2327 truncated.convert(Tgt, llvm::APFloat::rmNearestTiesToEven, &ignored); 2328 2329 return truncated.bitwiseIsEqual(value); 2330} 2331 2332/// Checks whether the given value, which currently has the given 2333/// source semantics, has the same value when coerced through the 2334/// target semantics. 2335/// 2336/// The value might be a vector of floats (or a complex number). 2337bool IsSameFloatAfterCast(const APValue &value, 2338 const llvm::fltSemantics &Src, 2339 const llvm::fltSemantics &Tgt) { 2340 if (value.isFloat()) 2341 return IsSameFloatAfterCast(value.getFloat(), Src, Tgt); 2342 2343 if (value.isVector()) { 2344 for (unsigned i = 0, e = value.getVectorLength(); i != e; ++i) 2345 if (!IsSameFloatAfterCast(value.getVectorElt(i), Src, Tgt)) 2346 return false; 2347 return true; 2348 } 2349 2350 assert(value.isComplexFloat()); 2351 return (IsSameFloatAfterCast(value.getComplexFloatReal(), Src, Tgt) && 2352 IsSameFloatAfterCast(value.getComplexFloatImag(), Src, Tgt)); 2353} 2354 2355void AnalyzeImplicitConversions(Sema &S, Expr *E); 2356 2357bool IsZero(Sema &S, Expr *E) { 2358 llvm::APSInt Value; 2359 return E->isIntegerConstantExpr(Value, S.Context) && Value == 0; 2360} 2361 2362void CheckTrivialUnsignedComparison(Sema &S, BinaryOperator *E) { 2363 BinaryOperator::Opcode op = E->getOpcode(); 2364 if (op == BinaryOperator::LT && IsZero(S, E->getRHS())) { 2365 S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison) 2366 << "< 0" << "false" 2367 << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); 2368 } else if (op == BinaryOperator::GE && IsZero(S, E->getRHS())) { 2369 S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison) 2370 << ">= 0" << "true" 2371 << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); 2372 } else if (op == BinaryOperator::GT && IsZero(S, E->getLHS())) { 2373 S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison) 2374 << "0 >" << "false" 2375 << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); 2376 } else if (op == BinaryOperator::LE && IsZero(S, E->getLHS())) { 2377 S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison) 2378 << "0 <=" << "true" 2379 << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); 2380 } 2381} 2382 2383/// Analyze the operands of the given comparison. Implements the 2384/// fallback case from AnalyzeComparison. 2385void AnalyzeImpConvsInComparison(Sema &S, BinaryOperator *E) { 2386 AnalyzeImplicitConversions(S, E->getLHS()); 2387 AnalyzeImplicitConversions(S, E->getRHS()); 2388} 2389 2390/// \brief Implements -Wsign-compare. 2391/// 2392/// \param lex the left-hand expression 2393/// \param rex the right-hand expression 2394/// \param OpLoc the location of the joining operator 2395/// \param BinOpc binary opcode or 0 2396void AnalyzeComparison(Sema &S, BinaryOperator *E) { 2397 // The type the comparison is being performed in. 2398 QualType T = E->getLHS()->getType(); 2399 assert(S.Context.hasSameUnqualifiedType(T, E->getRHS()->getType()) 2400 && "comparison with mismatched types"); 2401 2402 // We don't do anything special if this isn't an unsigned integral 2403 // comparison: we're only interested in integral comparisons, and 2404 // signed comparisons only happen in cases we don't care to warn about. 2405 if (!T->isUnsignedIntegerType()) 2406 return AnalyzeImpConvsInComparison(S, E); 2407 2408 Expr *lex = E->getLHS()->IgnoreParenImpCasts(); 2409 Expr *rex = E->getRHS()->IgnoreParenImpCasts(); 2410 2411 // Check to see if one of the (unmodified) operands is of different 2412 // signedness. 2413 Expr *signedOperand, *unsignedOperand; 2414 if (lex->getType()->isSignedIntegerType()) { 2415 assert(!rex->getType()->isSignedIntegerType() && 2416 "unsigned comparison between two signed integer expressions?"); 2417 signedOperand = lex; 2418 unsignedOperand = rex; 2419 } else if (rex->getType()->isSignedIntegerType()) { 2420 signedOperand = rex; 2421 unsignedOperand = lex; 2422 } else { 2423 CheckTrivialUnsignedComparison(S, E); 2424 return AnalyzeImpConvsInComparison(S, E); 2425 } 2426 2427 // Otherwise, calculate the effective range of the signed operand. 2428 IntRange signedRange = GetExprRange(S.Context, signedOperand); 2429 2430 // Go ahead and analyze implicit conversions in the operands. Note 2431 // that we skip the implicit conversions on both sides. 2432 AnalyzeImplicitConversions(S, lex); 2433 AnalyzeImplicitConversions(S, rex); 2434 2435 // If the signed range is non-negative, -Wsign-compare won't fire, 2436 // but we should still check for comparisons which are always true 2437 // or false. 2438 if (signedRange.NonNegative) 2439 return CheckTrivialUnsignedComparison(S, E); 2440 2441 // For (in)equality comparisons, if the unsigned operand is a 2442 // constant which cannot collide with a overflowed signed operand, 2443 // then reinterpreting the signed operand as unsigned will not 2444 // change the result of the comparison. 2445 if (E->isEqualityOp()) { 2446 unsigned comparisonWidth = S.Context.getIntWidth(T); 2447 IntRange unsignedRange = GetExprRange(S.Context, unsignedOperand); 2448 2449 // We should never be unable to prove that the unsigned operand is 2450 // non-negative. 2451 assert(unsignedRange.NonNegative && "unsigned range includes negative?"); 2452 2453 if (unsignedRange.Width < comparisonWidth) 2454 return; 2455 } 2456 2457 S.Diag(E->getOperatorLoc(), diag::warn_mixed_sign_comparison) 2458 << lex->getType() << rex->getType() 2459 << lex->getSourceRange() << rex->getSourceRange(); 2460} 2461 2462/// Diagnose an implicit cast; purely a helper for CheckImplicitConversion. 2463void DiagnoseImpCast(Sema &S, Expr *E, QualType T, unsigned diag) { 2464 S.Diag(E->getExprLoc(), diag) << E->getType() << T << E->getSourceRange(); 2465} 2466 2467void CheckImplicitConversion(Sema &S, Expr *E, QualType T, 2468 bool *ICContext = 0) { 2469 if (E->isTypeDependent() || E->isValueDependent()) return; 2470 2471 const Type *Source = S.Context.getCanonicalType(E->getType()).getTypePtr(); 2472 const Type *Target = S.Context.getCanonicalType(T).getTypePtr(); 2473 if (Source == Target) return; 2474 if (Target->isDependentType()) return; 2475 2476 // Never diagnose implicit casts to bool. 2477 if (Target->isSpecificBuiltinType(BuiltinType::Bool)) 2478 return; 2479 2480 // Strip vector types. 2481 if (isa<VectorType>(Source)) { 2482 if (!isa<VectorType>(Target)) 2483 return DiagnoseImpCast(S, E, T, diag::warn_impcast_vector_scalar); 2484 2485 Source = cast<VectorType>(Source)->getElementType().getTypePtr(); 2486 Target = cast<VectorType>(Target)->getElementType().getTypePtr(); 2487 } 2488 2489 // Strip complex types. 2490 if (isa<ComplexType>(Source)) { 2491 if (!isa<ComplexType>(Target)) 2492 return DiagnoseImpCast(S, E, T, diag::warn_impcast_complex_scalar); 2493 2494 Source = cast<ComplexType>(Source)->getElementType().getTypePtr(); 2495 Target = cast<ComplexType>(Target)->getElementType().getTypePtr(); 2496 } 2497 2498 const BuiltinType *SourceBT = dyn_cast<BuiltinType>(Source); 2499 const BuiltinType *TargetBT = dyn_cast<BuiltinType>(Target); 2500 2501 // If the source is floating point... 2502 if (SourceBT && SourceBT->isFloatingPoint()) { 2503 // ...and the target is floating point... 2504 if (TargetBT && TargetBT->isFloatingPoint()) { 2505 // ...then warn if we're dropping FP rank. 2506 2507 // Builtin FP kinds are ordered by increasing FP rank. 2508 if (SourceBT->getKind() > TargetBT->getKind()) { 2509 // Don't warn about float constants that are precisely 2510 // representable in the target type. 2511 Expr::EvalResult result; 2512 if (E->Evaluate(result, S.Context)) { 2513 // Value might be a float, a float vector, or a float complex. 2514 if (IsSameFloatAfterCast(result.Val, 2515 S.Context.getFloatTypeSemantics(QualType(TargetBT, 0)), 2516 S.Context.getFloatTypeSemantics(QualType(SourceBT, 0)))) 2517 return; 2518 } 2519 2520 DiagnoseImpCast(S, E, T, diag::warn_impcast_float_precision); 2521 } 2522 return; 2523 } 2524 2525 // If the target is integral, always warn. 2526 if ((TargetBT && TargetBT->isInteger())) 2527 // TODO: don't warn for integer values? 2528 DiagnoseImpCast(S, E, T, diag::warn_impcast_float_integer); 2529 2530 return; 2531 } 2532 2533 if (!Source->isIntegerType() || !Target->isIntegerType()) 2534 return; 2535 2536 IntRange SourceRange = GetExprRange(S.Context, E); 2537 IntRange TargetRange = IntRange::forCanonicalType(S.Context, Target); 2538 2539 if (SourceRange.Width > TargetRange.Width) { 2540 // People want to build with -Wshorten-64-to-32 and not -Wconversion 2541 // and by god we'll let them. 2542 if (SourceRange.Width == 64 && TargetRange.Width == 32) 2543 return DiagnoseImpCast(S, E, T, diag::warn_impcast_integer_64_32); 2544 return DiagnoseImpCast(S, E, T, diag::warn_impcast_integer_precision); 2545 } 2546 2547 if ((TargetRange.NonNegative && !SourceRange.NonNegative) || 2548 (!TargetRange.NonNegative && SourceRange.NonNegative && 2549 SourceRange.Width == TargetRange.Width)) { 2550 unsigned DiagID = diag::warn_impcast_integer_sign; 2551 2552 // Traditionally, gcc has warned about this under -Wsign-compare. 2553 // We also want to warn about it in -Wconversion. 2554 // So if -Wconversion is off, use a completely identical diagnostic 2555 // in the sign-compare group. 2556 // The conditional-checking code will 2557 if (ICContext) { 2558 DiagID = diag::warn_impcast_integer_sign_conditional; 2559 *ICContext = true; 2560 } 2561 2562 return DiagnoseImpCast(S, E, T, DiagID); 2563 } 2564 2565 return; 2566} 2567 2568void CheckConditionalOperator(Sema &S, ConditionalOperator *E, QualType T); 2569 2570void CheckConditionalOperand(Sema &S, Expr *E, QualType T, 2571 bool &ICContext) { 2572 E = E->IgnoreParenImpCasts(); 2573 2574 if (isa<ConditionalOperator>(E)) 2575 return CheckConditionalOperator(S, cast<ConditionalOperator>(E), T); 2576 2577 AnalyzeImplicitConversions(S, E); 2578 if (E->getType() != T) 2579 return CheckImplicitConversion(S, E, T, &ICContext); 2580 return; 2581} 2582 2583void CheckConditionalOperator(Sema &S, ConditionalOperator *E, QualType T) { 2584 AnalyzeImplicitConversions(S, E->getCond()); 2585 2586 bool Suspicious = false; 2587 CheckConditionalOperand(S, E->getTrueExpr(), T, Suspicious); 2588 CheckConditionalOperand(S, E->getFalseExpr(), T, Suspicious); 2589 2590 // If -Wconversion would have warned about either of the candidates 2591 // for a signedness conversion to the context type... 2592 if (!Suspicious) return; 2593 2594 // ...but it's currently ignored... 2595 if (S.Diags.getDiagnosticLevel(diag::warn_impcast_integer_sign_conditional)) 2596 return; 2597 2598 // ...and -Wsign-compare isn't... 2599 if (!S.Diags.getDiagnosticLevel(diag::warn_mixed_sign_conditional)) 2600 return; 2601 2602 // ...then check whether it would have warned about either of the 2603 // candidates for a signedness conversion to the condition type. 2604 if (E->getType() != T) { 2605 Suspicious = false; 2606 CheckImplicitConversion(S, E->getTrueExpr()->IgnoreParenImpCasts(), 2607 E->getType(), &Suspicious); 2608 if (!Suspicious) 2609 CheckImplicitConversion(S, E->getFalseExpr()->IgnoreParenImpCasts(), 2610 E->getType(), &Suspicious); 2611 if (!Suspicious) 2612 return; 2613 } 2614 2615 // If so, emit a diagnostic under -Wsign-compare. 2616 Expr *lex = E->getTrueExpr()->IgnoreParenImpCasts(); 2617 Expr *rex = E->getFalseExpr()->IgnoreParenImpCasts(); 2618 S.Diag(E->getQuestionLoc(), diag::warn_mixed_sign_conditional) 2619 << lex->getType() << rex->getType() 2620 << lex->getSourceRange() << rex->getSourceRange(); 2621} 2622 2623/// AnalyzeImplicitConversions - Find and report any interesting 2624/// implicit conversions in the given expression. There are a couple 2625/// of competing diagnostics here, -Wconversion and -Wsign-compare. 2626void AnalyzeImplicitConversions(Sema &S, Expr *OrigE) { 2627 QualType T = OrigE->getType(); 2628 Expr *E = OrigE->IgnoreParenImpCasts(); 2629 2630 // For conditional operators, we analyze the arguments as if they 2631 // were being fed directly into the output. 2632 if (isa<ConditionalOperator>(E)) { 2633 ConditionalOperator *CO = cast<ConditionalOperator>(E); 2634 CheckConditionalOperator(S, CO, T); 2635 return; 2636 } 2637 2638 // Go ahead and check any implicit conversions we might have skipped. 2639 // The non-canonical typecheck is just an optimization; 2640 // CheckImplicitConversion will filter out dead implicit conversions. 2641 if (E->getType() != T) 2642 CheckImplicitConversion(S, E, T); 2643 2644 // Now continue drilling into this expression. 2645 2646 // Skip past explicit casts. 2647 if (isa<ExplicitCastExpr>(E)) { 2648 E = cast<ExplicitCastExpr>(E)->getSubExpr()->IgnoreParenImpCasts(); 2649 return AnalyzeImplicitConversions(S, E); 2650 } 2651 2652 // Do a somewhat different check with comparison operators. 2653 if (isa<BinaryOperator>(E) && cast<BinaryOperator>(E)->isComparisonOp()) 2654 return AnalyzeComparison(S, cast<BinaryOperator>(E)); 2655 2656 // These break the otherwise-useful invariant below. Fortunately, 2657 // we don't really need to recurse into them, because any internal 2658 // expressions should have been analyzed already when they were 2659 // built into statements. 2660 if (isa<StmtExpr>(E)) return; 2661 2662 // Don't descend into unevaluated contexts. 2663 if (isa<SizeOfAlignOfExpr>(E)) return; 2664 2665 // Now just recurse over the expression's children. 2666 for (Stmt::child_iterator I = E->child_begin(), IE = E->child_end(); 2667 I != IE; ++I) 2668 AnalyzeImplicitConversions(S, cast<Expr>(*I)); 2669} 2670 2671} // end anonymous namespace 2672 2673/// Diagnoses "dangerous" implicit conversions within the given 2674/// expression (which is a full expression). Implements -Wconversion 2675/// and -Wsign-compare. 2676void Sema::CheckImplicitConversions(Expr *E) { 2677 // Don't diagnose in unevaluated contexts. 2678 if (ExprEvalContexts.back().Context == Sema::Unevaluated) 2679 return; 2680 2681 // Don't diagnose for value- or type-dependent expressions. 2682 if (E->isTypeDependent() || E->isValueDependent()) 2683 return; 2684 2685 AnalyzeImplicitConversions(*this, E); 2686} 2687 2688/// CheckParmsForFunctionDef - Check that the parameters of the given 2689/// function are appropriate for the definition of a function. This 2690/// takes care of any checks that cannot be performed on the 2691/// declaration itself, e.g., that the types of each of the function 2692/// parameters are complete. 2693bool Sema::CheckParmsForFunctionDef(FunctionDecl *FD) { 2694 bool HasInvalidParm = false; 2695 for (unsigned p = 0, NumParams = FD->getNumParams(); p < NumParams; ++p) { 2696 ParmVarDecl *Param = FD->getParamDecl(p); 2697 2698 // C99 6.7.5.3p4: the parameters in a parameter type list in a 2699 // function declarator that is part of a function definition of 2700 // that function shall not have incomplete type. 2701 // 2702 // This is also C++ [dcl.fct]p6. 2703 if (!Param->isInvalidDecl() && 2704 RequireCompleteType(Param->getLocation(), Param->getType(), 2705 diag::err_typecheck_decl_incomplete_type)) { 2706 Param->setInvalidDecl(); 2707 HasInvalidParm = true; 2708 } 2709 2710 // C99 6.9.1p5: If the declarator includes a parameter type list, the 2711 // declaration of each parameter shall include an identifier. 2712 if (Param->getIdentifier() == 0 && 2713 !Param->isImplicit() && 2714 !getLangOptions().CPlusPlus) 2715 Diag(Param->getLocation(), diag::err_parameter_name_omitted); 2716 2717 // C99 6.7.5.3p12: 2718 // If the function declarator is not part of a definition of that 2719 // function, parameters may have incomplete type and may use the [*] 2720 // notation in their sequences of declarator specifiers to specify 2721 // variable length array types. 2722 QualType PType = Param->getOriginalType(); 2723 if (const ArrayType *AT = Context.getAsArrayType(PType)) { 2724 if (AT->getSizeModifier() == ArrayType::Star) { 2725 // FIXME: This diagnosic should point the the '[*]' if source-location 2726 // information is added for it. 2727 Diag(Param->getLocation(), diag::err_array_star_in_function_definition); 2728 } 2729 } 2730 } 2731 2732 return HasInvalidParm; 2733} 2734