SemaChecking.cpp revision b075f1de60c17bd36ec1eaaf9e560224f8dbf7e4
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 // We need to figure out which concrete builtin this maps onto. For example, 423 // __sync_fetch_and_add with a 2 byte object turns into 424 // __sync_fetch_and_add_2. 425#define BUILTIN_ROW(x) \ 426 { Builtin::BI##x##_1, Builtin::BI##x##_2, Builtin::BI##x##_4, \ 427 Builtin::BI##x##_8, Builtin::BI##x##_16 } 428 429 static const unsigned BuiltinIndices[][5] = { 430 BUILTIN_ROW(__sync_fetch_and_add), 431 BUILTIN_ROW(__sync_fetch_and_sub), 432 BUILTIN_ROW(__sync_fetch_and_or), 433 BUILTIN_ROW(__sync_fetch_and_and), 434 BUILTIN_ROW(__sync_fetch_and_xor), 435 436 BUILTIN_ROW(__sync_add_and_fetch), 437 BUILTIN_ROW(__sync_sub_and_fetch), 438 BUILTIN_ROW(__sync_and_and_fetch), 439 BUILTIN_ROW(__sync_or_and_fetch), 440 BUILTIN_ROW(__sync_xor_and_fetch), 441 442 BUILTIN_ROW(__sync_val_compare_and_swap), 443 BUILTIN_ROW(__sync_bool_compare_and_swap), 444 BUILTIN_ROW(__sync_lock_test_and_set), 445 BUILTIN_ROW(__sync_lock_release) 446 }; 447#undef BUILTIN_ROW 448 449 // Determine the index of the size. 450 unsigned SizeIndex; 451 switch (Context.getTypeSizeInChars(ValType).getQuantity()) { 452 case 1: SizeIndex = 0; break; 453 case 2: SizeIndex = 1; break; 454 case 4: SizeIndex = 2; break; 455 case 8: SizeIndex = 3; break; 456 case 16: SizeIndex = 4; break; 457 default: 458 Diag(DRE->getLocStart(), diag::err_atomic_builtin_pointer_size) 459 << FirstArg->getType() << FirstArg->getSourceRange(); 460 return ExprError(); 461 } 462 463 // Each of these builtins has one pointer argument, followed by some number of 464 // values (0, 1 or 2) followed by a potentially empty varags list of stuff 465 // that we ignore. Find out which row of BuiltinIndices to read from as well 466 // as the number of fixed args. 467 unsigned BuiltinID = FDecl->getBuiltinID(); 468 unsigned BuiltinIndex, NumFixed = 1; 469 switch (BuiltinID) { 470 default: assert(0 && "Unknown overloaded atomic builtin!"); 471 case Builtin::BI__sync_fetch_and_add: BuiltinIndex = 0; break; 472 case Builtin::BI__sync_fetch_and_sub: BuiltinIndex = 1; break; 473 case Builtin::BI__sync_fetch_and_or: BuiltinIndex = 2; break; 474 case Builtin::BI__sync_fetch_and_and: BuiltinIndex = 3; break; 475 case Builtin::BI__sync_fetch_and_xor: BuiltinIndex = 4; break; 476 477 case Builtin::BI__sync_add_and_fetch: BuiltinIndex = 5; break; 478 case Builtin::BI__sync_sub_and_fetch: BuiltinIndex = 6; break; 479 case Builtin::BI__sync_and_and_fetch: BuiltinIndex = 7; break; 480 case Builtin::BI__sync_or_and_fetch: BuiltinIndex = 8; break; 481 case Builtin::BI__sync_xor_and_fetch: BuiltinIndex = 9; break; 482 483 case Builtin::BI__sync_val_compare_and_swap: 484 BuiltinIndex = 10; 485 NumFixed = 2; 486 break; 487 case Builtin::BI__sync_bool_compare_and_swap: 488 BuiltinIndex = 11; 489 NumFixed = 2; 490 break; 491 case Builtin::BI__sync_lock_test_and_set: BuiltinIndex = 12; break; 492 case Builtin::BI__sync_lock_release: 493 BuiltinIndex = 13; 494 NumFixed = 0; 495 break; 496 } 497 498 // Now that we know how many fixed arguments we expect, first check that we 499 // have at least that many. 500 if (TheCall->getNumArgs() < 1+NumFixed) { 501 Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args_at_least) 502 << 0 << 1+NumFixed << TheCall->getNumArgs() 503 << TheCall->getCallee()->getSourceRange(); 504 return ExprError(); 505 } 506 507 // Get the decl for the concrete builtin from this, we can tell what the 508 // concrete integer type we should convert to is. 509 unsigned NewBuiltinID = BuiltinIndices[BuiltinIndex][SizeIndex]; 510 const char *NewBuiltinName = Context.BuiltinInfo.GetName(NewBuiltinID); 511 IdentifierInfo *NewBuiltinII = PP.getIdentifierInfo(NewBuiltinName); 512 FunctionDecl *NewBuiltinDecl = 513 cast<FunctionDecl>(LazilyCreateBuiltin(NewBuiltinII, NewBuiltinID, 514 TUScope, false, DRE->getLocStart())); 515 516 // The first argument is by definition correct, we use it's type as the type 517 // of the entire operation. Walk the remaining arguments promoting them to 518 // the deduced value type. 519 for (unsigned i = 0; i != NumFixed; ++i) { 520 Expr *Arg = TheCall->getArg(i+1); 521 522 // If the argument is an implicit cast, then there was a promotion due to 523 // "...", just remove it now. 524 if (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Arg)) { 525 Arg = ICE->getSubExpr(); 526 ICE->setSubExpr(0); 527 ICE->Destroy(Context); 528 TheCall->setArg(i+1, Arg); 529 } 530 531 // GCC does an implicit conversion to the pointer or integer ValType. This 532 // can fail in some cases (1i -> int**), check for this error case now. 533 CastExpr::CastKind Kind = CastExpr::CK_Unknown; 534 CXXBaseSpecifierArray BasePath; 535 if (CheckCastTypes(Arg->getSourceRange(), ValType, Arg, Kind, BasePath)) 536 return ExprError(); 537 538 // Okay, we have something that *can* be converted to the right type. Check 539 // to see if there is a potentially weird extension going on here. This can 540 // happen when you do an atomic operation on something like an char* and 541 // pass in 42. The 42 gets converted to char. This is even more strange 542 // for things like 45.123 -> char, etc. 543 // FIXME: Do this check. 544 ImpCastExprToType(Arg, ValType, Kind); 545 TheCall->setArg(i+1, Arg); 546 } 547 548 // Switch the DeclRefExpr to refer to the new decl. 549 DRE->setDecl(NewBuiltinDecl); 550 DRE->setType(NewBuiltinDecl->getType()); 551 552 // Set the callee in the CallExpr. 553 // FIXME: This leaks the original parens and implicit casts. 554 Expr *PromotedCall = DRE; 555 UsualUnaryConversions(PromotedCall); 556 TheCall->setCallee(PromotedCall); 557 558 // Change the result type of the call to match the original value type. This 559 // is arbitrary, but the codegen for these builtins ins design to handle it 560 // gracefully. 561 TheCall->setType(ValType); 562 563 return move(TheCallResult); 564} 565 566 567/// CheckObjCString - Checks that the argument to the builtin 568/// CFString constructor is correct 569/// FIXME: GCC currently emits the following warning: 570/// "warning: input conversion stopped due to an input byte that does not 571/// belong to the input codeset UTF-8" 572/// Note: It might also make sense to do the UTF-16 conversion here (would 573/// simplify the backend). 574bool Sema::CheckObjCString(Expr *Arg) { 575 Arg = Arg->IgnoreParenCasts(); 576 StringLiteral *Literal = dyn_cast<StringLiteral>(Arg); 577 578 if (!Literal || Literal->isWide()) { 579 Diag(Arg->getLocStart(), diag::err_cfstring_literal_not_string_constant) 580 << Arg->getSourceRange(); 581 return true; 582 } 583 584 const char *Data = Literal->getStrData(); 585 unsigned Length = Literal->getByteLength(); 586 587 for (unsigned i = 0; i < Length; ++i) { 588 if (!Data[i]) { 589 Diag(getLocationOfStringLiteralByte(Literal, i), 590 diag::warn_cfstring_literal_contains_nul_character) 591 << Arg->getSourceRange(); 592 break; 593 } 594 } 595 596 return false; 597} 598 599/// SemaBuiltinVAStart - Check the arguments to __builtin_va_start for validity. 600/// Emit an error and return true on failure, return false on success. 601bool Sema::SemaBuiltinVAStart(CallExpr *TheCall) { 602 Expr *Fn = TheCall->getCallee(); 603 if (TheCall->getNumArgs() > 2) { 604 Diag(TheCall->getArg(2)->getLocStart(), 605 diag::err_typecheck_call_too_many_args) 606 << 0 /*function call*/ << 2 << TheCall->getNumArgs() 607 << Fn->getSourceRange() 608 << SourceRange(TheCall->getArg(2)->getLocStart(), 609 (*(TheCall->arg_end()-1))->getLocEnd()); 610 return true; 611 } 612 613 if (TheCall->getNumArgs() < 2) { 614 return Diag(TheCall->getLocEnd(), 615 diag::err_typecheck_call_too_few_args_at_least) 616 << 0 /*function call*/ << 2 << TheCall->getNumArgs(); 617 } 618 619 // Determine whether the current function is variadic or not. 620 BlockScopeInfo *CurBlock = getCurBlock(); 621 bool isVariadic; 622 if (CurBlock) 623 isVariadic = CurBlock->TheDecl->isVariadic(); 624 else if (FunctionDecl *FD = getCurFunctionDecl()) 625 isVariadic = FD->isVariadic(); 626 else 627 isVariadic = getCurMethodDecl()->isVariadic(); 628 629 if (!isVariadic) { 630 Diag(Fn->getLocStart(), diag::err_va_start_used_in_non_variadic_function); 631 return true; 632 } 633 634 // Verify that the second argument to the builtin is the last argument of the 635 // current function or method. 636 bool SecondArgIsLastNamedArgument = false; 637 const Expr *Arg = TheCall->getArg(1)->IgnoreParenCasts(); 638 639 if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Arg)) { 640 if (const ParmVarDecl *PV = dyn_cast<ParmVarDecl>(DR->getDecl())) { 641 // FIXME: This isn't correct for methods (results in bogus warning). 642 // Get the last formal in the current function. 643 const ParmVarDecl *LastArg; 644 if (CurBlock) 645 LastArg = *(CurBlock->TheDecl->param_end()-1); 646 else if (FunctionDecl *FD = getCurFunctionDecl()) 647 LastArg = *(FD->param_end()-1); 648 else 649 LastArg = *(getCurMethodDecl()->param_end()-1); 650 SecondArgIsLastNamedArgument = PV == LastArg; 651 } 652 } 653 654 if (!SecondArgIsLastNamedArgument) 655 Diag(TheCall->getArg(1)->getLocStart(), 656 diag::warn_second_parameter_of_va_start_not_last_named_argument); 657 return false; 658} 659 660/// SemaBuiltinUnorderedCompare - Handle functions like __builtin_isgreater and 661/// friends. This is declared to take (...), so we have to check everything. 662bool Sema::SemaBuiltinUnorderedCompare(CallExpr *TheCall) { 663 if (TheCall->getNumArgs() < 2) 664 return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args) 665 << 0 << 2 << TheCall->getNumArgs()/*function call*/; 666 if (TheCall->getNumArgs() > 2) 667 return Diag(TheCall->getArg(2)->getLocStart(), 668 diag::err_typecheck_call_too_many_args) 669 << 0 /*function call*/ << 2 << TheCall->getNumArgs() 670 << SourceRange(TheCall->getArg(2)->getLocStart(), 671 (*(TheCall->arg_end()-1))->getLocEnd()); 672 673 Expr *OrigArg0 = TheCall->getArg(0); 674 Expr *OrigArg1 = TheCall->getArg(1); 675 676 // Do standard promotions between the two arguments, returning their common 677 // type. 678 QualType Res = UsualArithmeticConversions(OrigArg0, OrigArg1, false); 679 680 // Make sure any conversions are pushed back into the call; this is 681 // type safe since unordered compare builtins are declared as "_Bool 682 // foo(...)". 683 TheCall->setArg(0, OrigArg0); 684 TheCall->setArg(1, OrigArg1); 685 686 if (OrigArg0->isTypeDependent() || OrigArg1->isTypeDependent()) 687 return false; 688 689 // If the common type isn't a real floating type, then the arguments were 690 // invalid for this operation. 691 if (!Res->isRealFloatingType()) 692 return Diag(OrigArg0->getLocStart(), 693 diag::err_typecheck_call_invalid_ordered_compare) 694 << OrigArg0->getType() << OrigArg1->getType() 695 << SourceRange(OrigArg0->getLocStart(), OrigArg1->getLocEnd()); 696 697 return false; 698} 699 700/// SemaBuiltinSemaBuiltinFPClassification - Handle functions like 701/// __builtin_isnan and friends. This is declared to take (...), so we have 702/// to check everything. We expect the last argument to be a floating point 703/// value. 704bool Sema::SemaBuiltinFPClassification(CallExpr *TheCall, unsigned NumArgs) { 705 if (TheCall->getNumArgs() < NumArgs) 706 return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args) 707 << 0 << NumArgs << TheCall->getNumArgs()/*function call*/; 708 if (TheCall->getNumArgs() > NumArgs) 709 return Diag(TheCall->getArg(NumArgs)->getLocStart(), 710 diag::err_typecheck_call_too_many_args) 711 << 0 /*function call*/ << NumArgs << TheCall->getNumArgs() 712 << SourceRange(TheCall->getArg(NumArgs)->getLocStart(), 713 (*(TheCall->arg_end()-1))->getLocEnd()); 714 715 Expr *OrigArg = TheCall->getArg(NumArgs-1); 716 717 if (OrigArg->isTypeDependent()) 718 return false; 719 720 // This operation requires a non-_Complex floating-point number. 721 if (!OrigArg->getType()->isRealFloatingType()) 722 return Diag(OrigArg->getLocStart(), 723 diag::err_typecheck_call_invalid_unary_fp) 724 << OrigArg->getType() << OrigArg->getSourceRange(); 725 726 // If this is an implicit conversion from float -> double, remove it. 727 if (ImplicitCastExpr *Cast = dyn_cast<ImplicitCastExpr>(OrigArg)) { 728 Expr *CastArg = Cast->getSubExpr(); 729 if (CastArg->getType()->isSpecificBuiltinType(BuiltinType::Float)) { 730 assert(Cast->getType()->isSpecificBuiltinType(BuiltinType::Double) && 731 "promotion from float to double is the only expected cast here"); 732 Cast->setSubExpr(0); 733 Cast->Destroy(Context); 734 TheCall->setArg(NumArgs-1, CastArg); 735 OrigArg = CastArg; 736 } 737 } 738 739 return false; 740} 741 742/// SemaBuiltinShuffleVector - Handle __builtin_shufflevector. 743// This is declared to take (...), so we have to check everything. 744Action::OwningExprResult Sema::SemaBuiltinShuffleVector(CallExpr *TheCall) { 745 if (TheCall->getNumArgs() < 2) 746 return ExprError(Diag(TheCall->getLocEnd(), 747 diag::err_typecheck_call_too_few_args_at_least) 748 << 0 /*function call*/ << 2 << TheCall->getNumArgs() 749 << TheCall->getSourceRange()); 750 751 // Determine which of the following types of shufflevector we're checking: 752 // 1) unary, vector mask: (lhs, mask) 753 // 2) binary, vector mask: (lhs, rhs, mask) 754 // 3) binary, scalar mask: (lhs, rhs, index, ..., index) 755 QualType resType = TheCall->getArg(0)->getType(); 756 unsigned numElements = 0; 757 758 if (!TheCall->getArg(0)->isTypeDependent() && 759 !TheCall->getArg(1)->isTypeDependent()) { 760 QualType LHSType = TheCall->getArg(0)->getType(); 761 QualType RHSType = TheCall->getArg(1)->getType(); 762 763 if (!LHSType->isVectorType() || !RHSType->isVectorType()) { 764 Diag(TheCall->getLocStart(), diag::err_shufflevector_non_vector) 765 << SourceRange(TheCall->getArg(0)->getLocStart(), 766 TheCall->getArg(1)->getLocEnd()); 767 return ExprError(); 768 } 769 770 numElements = LHSType->getAs<VectorType>()->getNumElements(); 771 unsigned numResElements = TheCall->getNumArgs() - 2; 772 773 // Check to see if we have a call with 2 vector arguments, the unary shuffle 774 // with mask. If so, verify that RHS is an integer vector type with the 775 // same number of elts as lhs. 776 if (TheCall->getNumArgs() == 2) { 777 if (!RHSType->isIntegerType() || 778 RHSType->getAs<VectorType>()->getNumElements() != numElements) 779 Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector) 780 << SourceRange(TheCall->getArg(1)->getLocStart(), 781 TheCall->getArg(1)->getLocEnd()); 782 numResElements = numElements; 783 } 784 else if (!Context.hasSameUnqualifiedType(LHSType, RHSType)) { 785 Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector) 786 << SourceRange(TheCall->getArg(0)->getLocStart(), 787 TheCall->getArg(1)->getLocEnd()); 788 return ExprError(); 789 } else if (numElements != numResElements) { 790 QualType eltType = LHSType->getAs<VectorType>()->getElementType(); 791 resType = Context.getVectorType(eltType, numResElements, 792 VectorType::NotAltiVec); 793 } 794 } 795 796 for (unsigned i = 2; i < TheCall->getNumArgs(); i++) { 797 if (TheCall->getArg(i)->isTypeDependent() || 798 TheCall->getArg(i)->isValueDependent()) 799 continue; 800 801 llvm::APSInt Result(32); 802 if (!TheCall->getArg(i)->isIntegerConstantExpr(Result, Context)) 803 return ExprError(Diag(TheCall->getLocStart(), 804 diag::err_shufflevector_nonconstant_argument) 805 << TheCall->getArg(i)->getSourceRange()); 806 807 if (Result.getActiveBits() > 64 || Result.getZExtValue() >= numElements*2) 808 return ExprError(Diag(TheCall->getLocStart(), 809 diag::err_shufflevector_argument_too_large) 810 << TheCall->getArg(i)->getSourceRange()); 811 } 812 813 llvm::SmallVector<Expr*, 32> exprs; 814 815 for (unsigned i = 0, e = TheCall->getNumArgs(); i != e; i++) { 816 exprs.push_back(TheCall->getArg(i)); 817 TheCall->setArg(i, 0); 818 } 819 820 return Owned(new (Context) ShuffleVectorExpr(Context, exprs.begin(), 821 exprs.size(), resType, 822 TheCall->getCallee()->getLocStart(), 823 TheCall->getRParenLoc())); 824} 825 826/// SemaBuiltinPrefetch - Handle __builtin_prefetch. 827// This is declared to take (const void*, ...) and can take two 828// optional constant int args. 829bool Sema::SemaBuiltinPrefetch(CallExpr *TheCall) { 830 unsigned NumArgs = TheCall->getNumArgs(); 831 832 if (NumArgs > 3) 833 return Diag(TheCall->getLocEnd(), 834 diag::err_typecheck_call_too_many_args_at_most) 835 << 0 /*function call*/ << 3 << NumArgs 836 << TheCall->getSourceRange(); 837 838 // Argument 0 is checked for us and the remaining arguments must be 839 // constant integers. 840 for (unsigned i = 1; i != NumArgs; ++i) { 841 Expr *Arg = TheCall->getArg(i); 842 843 llvm::APSInt Result; 844 if (SemaBuiltinConstantArg(TheCall, i, Result)) 845 return true; 846 847 // FIXME: gcc issues a warning and rewrites these to 0. These 848 // seems especially odd for the third argument since the default 849 // is 3. 850 if (i == 1) { 851 if (Result.getLimitedValue() > 1) 852 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 853 << "0" << "1" << Arg->getSourceRange(); 854 } else { 855 if (Result.getLimitedValue() > 3) 856 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 857 << "0" << "3" << Arg->getSourceRange(); 858 } 859 } 860 861 return false; 862} 863 864/// SemaBuiltinConstantArg - Handle a check if argument ArgNum of CallExpr 865/// TheCall is a constant expression. 866bool Sema::SemaBuiltinConstantArg(CallExpr *TheCall, int ArgNum, 867 llvm::APSInt &Result) { 868 Expr *Arg = TheCall->getArg(ArgNum); 869 DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts()); 870 FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl()); 871 872 if (Arg->isTypeDependent() || Arg->isValueDependent()) return false; 873 874 if (!Arg->isIntegerConstantExpr(Result, Context)) 875 return Diag(TheCall->getLocStart(), diag::err_constant_integer_arg_type) 876 << FDecl->getDeclName() << Arg->getSourceRange(); 877 878 return false; 879} 880 881/// SemaBuiltinObjectSize - Handle __builtin_object_size(void *ptr, 882/// int type). This simply type checks that type is one of the defined 883/// constants (0-3). 884// For compatability check 0-3, llvm only handles 0 and 2. 885bool Sema::SemaBuiltinObjectSize(CallExpr *TheCall) { 886 llvm::APSInt Result; 887 888 // Check constant-ness first. 889 if (SemaBuiltinConstantArg(TheCall, 1, Result)) 890 return true; 891 892 Expr *Arg = TheCall->getArg(1); 893 if (Result.getSExtValue() < 0 || Result.getSExtValue() > 3) { 894 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 895 << "0" << "3" << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); 896 } 897 898 return false; 899} 900 901/// SemaBuiltinLongjmp - Handle __builtin_longjmp(void *env[5], int val). 902/// This checks that val is a constant 1. 903bool Sema::SemaBuiltinLongjmp(CallExpr *TheCall) { 904 Expr *Arg = TheCall->getArg(1); 905 llvm::APSInt Result; 906 907 // TODO: This is less than ideal. Overload this to take a value. 908 if (SemaBuiltinConstantArg(TheCall, 1, Result)) 909 return true; 910 911 if (Result != 1) 912 return Diag(TheCall->getLocStart(), diag::err_builtin_longjmp_invalid_val) 913 << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); 914 915 return false; 916} 917 918// Handle i > 1 ? "x" : "y", recursivelly 919bool Sema::SemaCheckStringLiteral(const Expr *E, const CallExpr *TheCall, 920 bool HasVAListArg, 921 unsigned format_idx, unsigned firstDataArg, 922 bool isPrintf) { 923 924 if (E->isTypeDependent() || E->isValueDependent()) 925 return false; 926 927 switch (E->getStmtClass()) { 928 case Stmt::ConditionalOperatorClass: { 929 const ConditionalOperator *C = cast<ConditionalOperator>(E); 930 return SemaCheckStringLiteral(C->getTrueExpr(), TheCall, HasVAListArg, 931 format_idx, firstDataArg, isPrintf) 932 && SemaCheckStringLiteral(C->getRHS(), TheCall, HasVAListArg, 933 format_idx, firstDataArg, isPrintf); 934 } 935 936 case Stmt::ImplicitCastExprClass: { 937 const ImplicitCastExpr *Expr = cast<ImplicitCastExpr>(E); 938 return SemaCheckStringLiteral(Expr->getSubExpr(), TheCall, HasVAListArg, 939 format_idx, firstDataArg, isPrintf); 940 } 941 942 case Stmt::ParenExprClass: { 943 const ParenExpr *Expr = cast<ParenExpr>(E); 944 return SemaCheckStringLiteral(Expr->getSubExpr(), TheCall, HasVAListArg, 945 format_idx, firstDataArg, isPrintf); 946 } 947 948 case Stmt::DeclRefExprClass: { 949 const DeclRefExpr *DR = cast<DeclRefExpr>(E); 950 951 // As an exception, do not flag errors for variables binding to 952 // const string literals. 953 if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) { 954 bool isConstant = false; 955 QualType T = DR->getType(); 956 957 if (const ArrayType *AT = Context.getAsArrayType(T)) { 958 isConstant = AT->getElementType().isConstant(Context); 959 } else if (const PointerType *PT = T->getAs<PointerType>()) { 960 isConstant = T.isConstant(Context) && 961 PT->getPointeeType().isConstant(Context); 962 } 963 964 if (isConstant) { 965 if (const Expr *Init = VD->getAnyInitializer()) 966 return SemaCheckStringLiteral(Init, TheCall, 967 HasVAListArg, format_idx, firstDataArg, 968 isPrintf); 969 } 970 971 // For vprintf* functions (i.e., HasVAListArg==true), we add a 972 // special check to see if the format string is a function parameter 973 // of the function calling the printf function. If the function 974 // has an attribute indicating it is a printf-like function, then we 975 // should suppress warnings concerning non-literals being used in a call 976 // to a vprintf function. For example: 977 // 978 // void 979 // logmessage(char const *fmt __attribute__ (format (printf, 1, 2)), ...){ 980 // va_list ap; 981 // va_start(ap, fmt); 982 // vprintf(fmt, ap); // Do NOT emit a warning about "fmt". 983 // ... 984 // 985 // 986 // FIXME: We don't have full attribute support yet, so just check to see 987 // if the argument is a DeclRefExpr that references a parameter. We'll 988 // add proper support for checking the attribute later. 989 if (HasVAListArg) 990 if (isa<ParmVarDecl>(VD)) 991 return true; 992 } 993 994 return false; 995 } 996 997 case Stmt::CallExprClass: { 998 const CallExpr *CE = cast<CallExpr>(E); 999 if (const ImplicitCastExpr *ICE 1000 = dyn_cast<ImplicitCastExpr>(CE->getCallee())) { 1001 if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(ICE->getSubExpr())) { 1002 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(DRE->getDecl())) { 1003 if (const FormatArgAttr *FA = FD->getAttr<FormatArgAttr>()) { 1004 unsigned ArgIndex = FA->getFormatIdx(); 1005 const Expr *Arg = CE->getArg(ArgIndex - 1); 1006 1007 return SemaCheckStringLiteral(Arg, TheCall, HasVAListArg, 1008 format_idx, firstDataArg, isPrintf); 1009 } 1010 } 1011 } 1012 } 1013 1014 return false; 1015 } 1016 case Stmt::ObjCStringLiteralClass: 1017 case Stmt::StringLiteralClass: { 1018 const StringLiteral *StrE = NULL; 1019 1020 if (const ObjCStringLiteral *ObjCFExpr = dyn_cast<ObjCStringLiteral>(E)) 1021 StrE = ObjCFExpr->getString(); 1022 else 1023 StrE = cast<StringLiteral>(E); 1024 1025 if (StrE) { 1026 CheckFormatString(StrE, E, TheCall, HasVAListArg, format_idx, 1027 firstDataArg, isPrintf); 1028 return true; 1029 } 1030 1031 return false; 1032 } 1033 1034 default: 1035 return false; 1036 } 1037} 1038 1039void 1040Sema::CheckNonNullArguments(const NonNullAttr *NonNull, 1041 const CallExpr *TheCall) { 1042 for (NonNullAttr::iterator i = NonNull->begin(), e = NonNull->end(); 1043 i != e; ++i) { 1044 const Expr *ArgExpr = TheCall->getArg(*i); 1045 if (ArgExpr->isNullPointerConstant(Context, 1046 Expr::NPC_ValueDependentIsNotNull)) 1047 Diag(TheCall->getCallee()->getLocStart(), diag::warn_null_arg) 1048 << ArgExpr->getSourceRange(); 1049 } 1050} 1051 1052/// CheckPrintfScanfArguments - Check calls to printf and scanf (and similar 1053/// functions) for correct use of format strings. 1054void 1055Sema::CheckPrintfScanfArguments(const CallExpr *TheCall, bool HasVAListArg, 1056 unsigned format_idx, unsigned firstDataArg, 1057 bool isPrintf) { 1058 1059 const Expr *Fn = TheCall->getCallee(); 1060 1061 // The way the format attribute works in GCC, the implicit this argument 1062 // of member functions is counted. However, it doesn't appear in our own 1063 // lists, so decrement format_idx in that case. 1064 if (isa<CXXMemberCallExpr>(TheCall)) { 1065 // Catch a format attribute mistakenly referring to the object argument. 1066 if (format_idx == 0) 1067 return; 1068 --format_idx; 1069 if(firstDataArg != 0) 1070 --firstDataArg; 1071 } 1072 1073 // CHECK: printf/scanf-like function is called with no format string. 1074 if (format_idx >= TheCall->getNumArgs()) { 1075 Diag(TheCall->getRParenLoc(), diag::warn_missing_format_string) 1076 << Fn->getSourceRange(); 1077 return; 1078 } 1079 1080 const Expr *OrigFormatExpr = TheCall->getArg(format_idx)->IgnoreParenCasts(); 1081 1082 // CHECK: format string is not a string literal. 1083 // 1084 // Dynamically generated format strings are difficult to 1085 // automatically vet at compile time. Requiring that format strings 1086 // are string literals: (1) permits the checking of format strings by 1087 // the compiler and thereby (2) can practically remove the source of 1088 // many format string exploits. 1089 1090 // Format string can be either ObjC string (e.g. @"%d") or 1091 // C string (e.g. "%d") 1092 // ObjC string uses the same format specifiers as C string, so we can use 1093 // the same format string checking logic for both ObjC and C strings. 1094 if (SemaCheckStringLiteral(OrigFormatExpr, TheCall, HasVAListArg, format_idx, 1095 firstDataArg, isPrintf)) 1096 return; // Literal format string found, check done! 1097 1098 // If there are no arguments specified, warn with -Wformat-security, otherwise 1099 // warn only with -Wformat-nonliteral. 1100 if (TheCall->getNumArgs() == format_idx+1) 1101 Diag(TheCall->getArg(format_idx)->getLocStart(), 1102 diag::warn_format_nonliteral_noargs) 1103 << OrigFormatExpr->getSourceRange(); 1104 else 1105 Diag(TheCall->getArg(format_idx)->getLocStart(), 1106 diag::warn_format_nonliteral) 1107 << OrigFormatExpr->getSourceRange(); 1108} 1109 1110namespace { 1111class CheckFormatHandler : public analyze_format_string::FormatStringHandler { 1112protected: 1113 Sema &S; 1114 const StringLiteral *FExpr; 1115 const Expr *OrigFormatExpr; 1116 const unsigned FirstDataArg; 1117 const unsigned NumDataArgs; 1118 const bool IsObjCLiteral; 1119 const char *Beg; // Start of format string. 1120 const bool HasVAListArg; 1121 const CallExpr *TheCall; 1122 unsigned FormatIdx; 1123 llvm::BitVector CoveredArgs; 1124 bool usesPositionalArgs; 1125 bool atFirstArg; 1126public: 1127 CheckFormatHandler(Sema &s, const StringLiteral *fexpr, 1128 const Expr *origFormatExpr, unsigned firstDataArg, 1129 unsigned numDataArgs, bool isObjCLiteral, 1130 const char *beg, bool hasVAListArg, 1131 const CallExpr *theCall, unsigned formatIdx) 1132 : S(s), FExpr(fexpr), OrigFormatExpr(origFormatExpr), 1133 FirstDataArg(firstDataArg), 1134 NumDataArgs(numDataArgs), 1135 IsObjCLiteral(isObjCLiteral), Beg(beg), 1136 HasVAListArg(hasVAListArg), 1137 TheCall(theCall), FormatIdx(formatIdx), 1138 usesPositionalArgs(false), atFirstArg(true) { 1139 CoveredArgs.resize(numDataArgs); 1140 CoveredArgs.reset(); 1141 } 1142 1143 void DoneProcessing(); 1144 1145 void HandleIncompleteSpecifier(const char *startSpecifier, 1146 unsigned specifierLen); 1147 1148 virtual void HandleInvalidPosition(const char *startSpecifier, 1149 unsigned specifierLen, 1150 analyze_format_string::PositionContext p); 1151 1152 virtual void HandleZeroPosition(const char *startPos, unsigned posLen); 1153 1154 void HandleNullChar(const char *nullCharacter); 1155 1156protected: 1157 SourceRange getFormatStringRange(); 1158 CharSourceRange getSpecifierRange(const char *startSpecifier, 1159 unsigned specifierLen); 1160 SourceLocation getLocationOfByte(const char *x); 1161 1162 const Expr *getDataArg(unsigned i) const; 1163}; 1164} 1165 1166SourceRange CheckFormatHandler::getFormatStringRange() { 1167 return OrigFormatExpr->getSourceRange(); 1168} 1169 1170CharSourceRange CheckFormatHandler:: 1171getSpecifierRange(const char *startSpecifier, unsigned specifierLen) { 1172 SourceLocation Start = getLocationOfByte(startSpecifier); 1173 SourceLocation End = getLocationOfByte(startSpecifier + specifierLen - 1); 1174 1175 // Advance the end SourceLocation by one due to half-open ranges. 1176 End = End.getFileLocWithOffset(1); 1177 1178 return CharSourceRange::getCharRange(Start, End); 1179} 1180 1181SourceLocation CheckFormatHandler::getLocationOfByte(const char *x) { 1182 return S.getLocationOfStringLiteralByte(FExpr, x - Beg); 1183} 1184 1185void CheckFormatHandler::HandleIncompleteSpecifier(const char *startSpecifier, 1186 unsigned specifierLen){ 1187 SourceLocation Loc = getLocationOfByte(startSpecifier); 1188 S.Diag(Loc, diag::warn_printf_incomplete_specifier) 1189 << getSpecifierRange(startSpecifier, specifierLen); 1190} 1191 1192void 1193CheckFormatHandler::HandleInvalidPosition(const char *startPos, unsigned posLen, 1194 analyze_format_string::PositionContext p) { 1195 SourceLocation Loc = getLocationOfByte(startPos); 1196 S.Diag(Loc, diag::warn_format_invalid_positional_specifier) 1197 << (unsigned) p << getSpecifierRange(startPos, posLen); 1198} 1199 1200void CheckFormatHandler::HandleZeroPosition(const char *startPos, 1201 unsigned posLen) { 1202 SourceLocation Loc = getLocationOfByte(startPos); 1203 S.Diag(Loc, diag::warn_format_zero_positional_specifier) 1204 << getSpecifierRange(startPos, posLen); 1205} 1206 1207void CheckFormatHandler::HandleNullChar(const char *nullCharacter) { 1208 // The presence of a null character is likely an error. 1209 S.Diag(getLocationOfByte(nullCharacter), 1210 diag::warn_printf_format_string_contains_null_char) 1211 << getFormatStringRange(); 1212} 1213 1214const Expr *CheckFormatHandler::getDataArg(unsigned i) const { 1215 return TheCall->getArg(FirstDataArg + i); 1216} 1217 1218void CheckFormatHandler::DoneProcessing() { 1219 // Does the number of data arguments exceed the number of 1220 // format conversions in the format string? 1221 if (!HasVAListArg) { 1222 // Find any arguments that weren't covered. 1223 CoveredArgs.flip(); 1224 signed notCoveredArg = CoveredArgs.find_first(); 1225 if (notCoveredArg >= 0) { 1226 assert((unsigned)notCoveredArg < NumDataArgs); 1227 S.Diag(getDataArg((unsigned) notCoveredArg)->getLocStart(), 1228 diag::warn_printf_data_arg_not_used) 1229 << getFormatStringRange(); 1230 } 1231 } 1232} 1233 1234//===--- CHECK: Printf format string checking ------------------------------===// 1235 1236namespace { 1237class CheckPrintfHandler : public CheckFormatHandler { 1238public: 1239 CheckPrintfHandler(Sema &s, const StringLiteral *fexpr, 1240 const Expr *origFormatExpr, unsigned firstDataArg, 1241 unsigned numDataArgs, bool isObjCLiteral, 1242 const char *beg, bool hasVAListArg, 1243 const CallExpr *theCall, unsigned formatIdx) 1244 : CheckFormatHandler(s, fexpr, origFormatExpr, firstDataArg, 1245 numDataArgs, isObjCLiteral, beg, hasVAListArg, 1246 theCall, formatIdx) {} 1247 1248 1249 bool HandleInvalidPrintfConversionSpecifier( 1250 const analyze_printf::PrintfSpecifier &FS, 1251 const char *startSpecifier, 1252 unsigned specifierLen); 1253 1254 bool HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier &FS, 1255 const char *startSpecifier, 1256 unsigned specifierLen); 1257 1258 bool HandleAmount(const analyze_format_string::OptionalAmount &Amt, unsigned k, 1259 const char *startSpecifier, unsigned specifierLen); 1260 void HandleInvalidAmount(const analyze_printf::PrintfSpecifier &FS, 1261 const analyze_printf::OptionalAmount &Amt, 1262 unsigned type, 1263 const char *startSpecifier, unsigned specifierLen); 1264 void HandleFlag(const analyze_printf::PrintfSpecifier &FS, 1265 const analyze_printf::OptionalFlag &flag, 1266 const char *startSpecifier, unsigned specifierLen); 1267 void HandleIgnoredFlag(const analyze_printf::PrintfSpecifier &FS, 1268 const analyze_printf::OptionalFlag &ignoredFlag, 1269 const analyze_printf::OptionalFlag &flag, 1270 const char *startSpecifier, unsigned specifierLen); 1271}; 1272} 1273 1274bool CheckPrintfHandler::HandleInvalidPrintfConversionSpecifier( 1275 const analyze_printf::PrintfSpecifier &FS, 1276 const char *startSpecifier, 1277 unsigned specifierLen) { 1278 1279 unsigned argIndex = FS.getArgIndex(); 1280 bool keepGoing = true; 1281 if (argIndex < NumDataArgs) { 1282 // Consider the argument coverered, even though the specifier doesn't 1283 // make sense. 1284 CoveredArgs.set(argIndex); 1285 } 1286 else { 1287 // If argIndex exceeds the number of data arguments we 1288 // don't issue a warning because that is just a cascade of warnings (and 1289 // they may have intended '%%' anyway). We don't want to continue processing 1290 // the format string after this point, however, as we will like just get 1291 // gibberish when trying to match arguments. 1292 keepGoing = false; 1293 } 1294 1295 const analyze_printf::ConversionSpecifier &CS = 1296 FS.getConversionSpecifier(); 1297 SourceLocation Loc = getLocationOfByte(CS.getStart()); 1298 S.Diag(Loc, diag::warn_printf_invalid_conversion) 1299 << llvm::StringRef(CS.getStart(), CS.getLength()) 1300 << getSpecifierRange(startSpecifier, specifierLen); 1301 1302 return keepGoing; 1303} 1304 1305bool CheckPrintfHandler::HandleAmount( 1306 const analyze_format_string::OptionalAmount &Amt, 1307 unsigned k, const char *startSpecifier, 1308 unsigned specifierLen) { 1309 1310 if (Amt.hasDataArgument()) { 1311 if (!HasVAListArg) { 1312 unsigned argIndex = Amt.getArgIndex(); 1313 if (argIndex >= NumDataArgs) { 1314 S.Diag(getLocationOfByte(Amt.getStart()), 1315 diag::warn_printf_asterisk_missing_arg) 1316 << k << getSpecifierRange(startSpecifier, specifierLen); 1317 // Don't do any more checking. We will just emit 1318 // spurious errors. 1319 return false; 1320 } 1321 1322 // Type check the data argument. It should be an 'int'. 1323 // Although not in conformance with C99, we also allow the argument to be 1324 // an 'unsigned int' as that is a reasonably safe case. GCC also 1325 // doesn't emit a warning for that case. 1326 CoveredArgs.set(argIndex); 1327 const Expr *Arg = getDataArg(argIndex); 1328 QualType T = Arg->getType(); 1329 1330 const analyze_printf::ArgTypeResult &ATR = Amt.getArgType(S.Context); 1331 assert(ATR.isValid()); 1332 1333 if (!ATR.matchesType(S.Context, T)) { 1334 S.Diag(getLocationOfByte(Amt.getStart()), 1335 diag::warn_printf_asterisk_wrong_type) 1336 << k 1337 << ATR.getRepresentativeType(S.Context) << T 1338 << getSpecifierRange(startSpecifier, specifierLen) 1339 << Arg->getSourceRange(); 1340 // Don't do any more checking. We will just emit 1341 // spurious errors. 1342 return false; 1343 } 1344 } 1345 } 1346 return true; 1347} 1348 1349void CheckPrintfHandler::HandleInvalidAmount( 1350 const analyze_printf::PrintfSpecifier &FS, 1351 const analyze_printf::OptionalAmount &Amt, 1352 unsigned type, 1353 const char *startSpecifier, 1354 unsigned specifierLen) { 1355 const analyze_printf::ConversionSpecifier &CS = FS.getConversionSpecifier(); 1356 switch (Amt.getHowSpecified()) { 1357 case analyze_printf::OptionalAmount::Constant: 1358 S.Diag(getLocationOfByte(Amt.getStart()), 1359 diag::warn_printf_nonsensical_optional_amount) 1360 << type 1361 << CS.toString() 1362 << getSpecifierRange(startSpecifier, specifierLen) 1363 << FixItHint::CreateRemoval(getSpecifierRange(Amt.getStart(), 1364 Amt.getConstantLength())); 1365 break; 1366 1367 default: 1368 S.Diag(getLocationOfByte(Amt.getStart()), 1369 diag::warn_printf_nonsensical_optional_amount) 1370 << type 1371 << CS.toString() 1372 << getSpecifierRange(startSpecifier, specifierLen); 1373 break; 1374 } 1375} 1376 1377void CheckPrintfHandler::HandleFlag(const analyze_printf::PrintfSpecifier &FS, 1378 const analyze_printf::OptionalFlag &flag, 1379 const char *startSpecifier, 1380 unsigned specifierLen) { 1381 // Warn about pointless flag with a fixit removal. 1382 const analyze_printf::ConversionSpecifier &CS = FS.getConversionSpecifier(); 1383 S.Diag(getLocationOfByte(flag.getPosition()), 1384 diag::warn_printf_nonsensical_flag) 1385 << flag.toString() << CS.toString() 1386 << getSpecifierRange(startSpecifier, specifierLen) 1387 << FixItHint::CreateRemoval(getSpecifierRange(flag.getPosition(), 1)); 1388} 1389 1390void CheckPrintfHandler::HandleIgnoredFlag( 1391 const analyze_printf::PrintfSpecifier &FS, 1392 const analyze_printf::OptionalFlag &ignoredFlag, 1393 const analyze_printf::OptionalFlag &flag, 1394 const char *startSpecifier, 1395 unsigned specifierLen) { 1396 // Warn about ignored flag with a fixit removal. 1397 S.Diag(getLocationOfByte(ignoredFlag.getPosition()), 1398 diag::warn_printf_ignored_flag) 1399 << ignoredFlag.toString() << flag.toString() 1400 << getSpecifierRange(startSpecifier, specifierLen) 1401 << FixItHint::CreateRemoval(getSpecifierRange( 1402 ignoredFlag.getPosition(), 1)); 1403} 1404 1405bool 1406CheckPrintfHandler::HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier 1407 &FS, 1408 const char *startSpecifier, 1409 unsigned specifierLen) { 1410 1411 using namespace analyze_printf; 1412 const ConversionSpecifier &CS = FS.getConversionSpecifier(); 1413 1414 if (atFirstArg) { 1415 atFirstArg = false; 1416 usesPositionalArgs = FS.usesPositionalArg(); 1417 } 1418 else if (usesPositionalArgs != FS.usesPositionalArg()) { 1419 // Cannot mix-and-match positional and non-positional arguments. 1420 S.Diag(getLocationOfByte(CS.getStart()), 1421 diag::warn_format_mix_positional_nonpositional_args) 1422 << getSpecifierRange(startSpecifier, specifierLen); 1423 return false; 1424 } 1425 1426 // First check if the field width, precision, and conversion specifier 1427 // have matching data arguments. 1428 if (!HandleAmount(FS.getFieldWidth(), /* field width */ 0, 1429 startSpecifier, specifierLen)) { 1430 return false; 1431 } 1432 1433 if (!HandleAmount(FS.getPrecision(), /* precision */ 1, 1434 startSpecifier, specifierLen)) { 1435 return false; 1436 } 1437 1438 if (!CS.consumesDataArgument()) { 1439 // FIXME: Technically specifying a precision or field width here 1440 // makes no sense. Worth issuing a warning at some point. 1441 return true; 1442 } 1443 1444 // Consume the argument. 1445 unsigned argIndex = FS.getArgIndex(); 1446 if (argIndex < NumDataArgs) { 1447 // The check to see if the argIndex is valid will come later. 1448 // We set the bit here because we may exit early from this 1449 // function if we encounter some other error. 1450 CoveredArgs.set(argIndex); 1451 } 1452 1453 // Check for using an Objective-C specific conversion specifier 1454 // in a non-ObjC literal. 1455 if (!IsObjCLiteral && CS.isObjCArg()) { 1456 return HandleInvalidPrintfConversionSpecifier(FS, startSpecifier, 1457 specifierLen); 1458 } 1459 1460 // Check for invalid use of field width 1461 if (!FS.hasValidFieldWidth()) { 1462 HandleInvalidAmount(FS, FS.getFieldWidth(), /* field width */ 0, 1463 startSpecifier, specifierLen); 1464 } 1465 1466 // Check for invalid use of precision 1467 if (!FS.hasValidPrecision()) { 1468 HandleInvalidAmount(FS, FS.getPrecision(), /* precision */ 1, 1469 startSpecifier, specifierLen); 1470 } 1471 1472 // Check each flag does not conflict with any other component. 1473 if (!FS.hasValidLeadingZeros()) 1474 HandleFlag(FS, FS.hasLeadingZeros(), startSpecifier, specifierLen); 1475 if (!FS.hasValidPlusPrefix()) 1476 HandleFlag(FS, FS.hasPlusPrefix(), startSpecifier, specifierLen); 1477 if (!FS.hasValidSpacePrefix()) 1478 HandleFlag(FS, FS.hasSpacePrefix(), startSpecifier, specifierLen); 1479 if (!FS.hasValidAlternativeForm()) 1480 HandleFlag(FS, FS.hasAlternativeForm(), startSpecifier, specifierLen); 1481 if (!FS.hasValidLeftJustified()) 1482 HandleFlag(FS, FS.isLeftJustified(), startSpecifier, specifierLen); 1483 1484 // Check that flags are not ignored by another flag 1485 if (FS.hasSpacePrefix() && FS.hasPlusPrefix()) // ' ' ignored by '+' 1486 HandleIgnoredFlag(FS, FS.hasSpacePrefix(), FS.hasPlusPrefix(), 1487 startSpecifier, specifierLen); 1488 if (FS.hasLeadingZeros() && FS.isLeftJustified()) // '0' ignored by '-' 1489 HandleIgnoredFlag(FS, FS.hasLeadingZeros(), FS.isLeftJustified(), 1490 startSpecifier, specifierLen); 1491 1492 // Check the length modifier is valid with the given conversion specifier. 1493 const LengthModifier &LM = FS.getLengthModifier(); 1494 if (!FS.hasValidLengthModifier()) 1495 S.Diag(getLocationOfByte(LM.getStart()), 1496 diag::warn_printf_nonsensical_length) 1497 << LM.toString() << CS.toString() 1498 << getSpecifierRange(startSpecifier, specifierLen) 1499 << FixItHint::CreateRemoval(getSpecifierRange(LM.getStart(), 1500 LM.getLength())); 1501 1502 // Are we using '%n'? 1503 if (CS.getKind() == ConversionSpecifier::OutIntPtrArg) { 1504 // Issue a warning about this being a possible security issue. 1505 S.Diag(getLocationOfByte(CS.getStart()), diag::warn_printf_write_back) 1506 << getSpecifierRange(startSpecifier, specifierLen); 1507 // Continue checking the other format specifiers. 1508 return true; 1509 } 1510 1511 // The remaining checks depend on the data arguments. 1512 if (HasVAListArg) 1513 return true; 1514 1515 if (argIndex >= NumDataArgs) { 1516 if (FS.usesPositionalArg()) { 1517 S.Diag(getLocationOfByte(CS.getStart()), 1518 diag::warn_printf_positional_arg_exceeds_data_args) 1519 << (argIndex+1) << NumDataArgs 1520 << getSpecifierRange(startSpecifier, specifierLen); 1521 } 1522 else { 1523 S.Diag(getLocationOfByte(CS.getStart()), 1524 diag::warn_printf_insufficient_data_args) 1525 << getSpecifierRange(startSpecifier, specifierLen); 1526 } 1527 1528 // Don't do any more checking. 1529 return false; 1530 } 1531 1532 // Now type check the data expression that matches the 1533 // format specifier. 1534 const Expr *Ex = getDataArg(argIndex); 1535 const analyze_printf::ArgTypeResult &ATR = FS.getArgType(S.Context); 1536 if (ATR.isValid() && !ATR.matchesType(S.Context, Ex->getType())) { 1537 // Check if we didn't match because of an implicit cast from a 'char' 1538 // or 'short' to an 'int'. This is done because printf is a varargs 1539 // function. 1540 if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Ex)) 1541 if (ICE->getType() == S.Context.IntTy) 1542 if (ATR.matchesType(S.Context, ICE->getSubExpr()->getType())) 1543 return true; 1544 1545 // We may be able to offer a FixItHint if it is a supported type. 1546 PrintfSpecifier fixedFS = FS; 1547 bool success = fixedFS.fixType(Ex->getType()); 1548 1549 if (success) { 1550 // Get the fix string from the fixed format specifier 1551 llvm::SmallString<128> buf; 1552 llvm::raw_svector_ostream os(buf); 1553 fixedFS.toString(os); 1554 1555 S.Diag(getLocationOfByte(CS.getStart()), 1556 diag::warn_printf_conversion_argument_type_mismatch) 1557 << ATR.getRepresentativeType(S.Context) << Ex->getType() 1558 << getSpecifierRange(startSpecifier, specifierLen) 1559 << Ex->getSourceRange() 1560 << FixItHint::CreateReplacement( 1561 getSpecifierRange(startSpecifier, specifierLen), 1562 os.str()); 1563 } 1564 else { 1565 S.Diag(getLocationOfByte(CS.getStart()), 1566 diag::warn_printf_conversion_argument_type_mismatch) 1567 << ATR.getRepresentativeType(S.Context) << Ex->getType() 1568 << getSpecifierRange(startSpecifier, specifierLen) 1569 << Ex->getSourceRange(); 1570 } 1571 } 1572 1573 return true; 1574} 1575 1576//===--- CHECK: Scanf format string checking ------------------------------===// 1577 1578namespace { 1579class CheckScanfHandler : public CheckFormatHandler { 1580public: 1581 CheckScanfHandler(Sema &s, const StringLiteral *fexpr, 1582 const Expr *origFormatExpr, unsigned firstDataArg, 1583 unsigned numDataArgs, bool isObjCLiteral, 1584 const char *beg, bool hasVAListArg, 1585 const CallExpr *theCall, unsigned formatIdx) 1586 : CheckFormatHandler(s, fexpr, origFormatExpr, firstDataArg, 1587 numDataArgs, isObjCLiteral, beg, hasVAListArg, 1588 theCall, formatIdx) {} 1589 1590 bool HandleScanfSpecifier(const analyze_scanf::ScanfSpecifier &FS, 1591 const char *startSpecifier, 1592 unsigned specifierLen); 1593 1594 void HandleIncompleteScanList(const char *start, const char *end); 1595}; 1596} 1597 1598void CheckScanfHandler::HandleIncompleteScanList(const char *start, 1599 const char *end) { 1600 S.Diag(getLocationOfByte(end), diag::warn_scanf_scanlist_incomplete) 1601 << getSpecifierRange(start, end - start); 1602} 1603 1604bool CheckScanfHandler::HandleScanfSpecifier( 1605 const analyze_scanf::ScanfSpecifier &FS, 1606 const char *startSpecifier, 1607 unsigned specifierLen) { 1608 1609 using namespace analyze_scanf; 1610 using namespace analyze_format_string; 1611 1612 const ConversionSpecifier &CS = FS.getConversionSpecifier(); 1613 1614 // FIXME: Handle case where '%' and '*' don't consume an argument. 1615 // This needs to be done for the printf case as well. 1616 if (atFirstArg) { 1617 atFirstArg = false; 1618 usesPositionalArgs = FS.usesPositionalArg(); 1619 } 1620 else if (usesPositionalArgs != FS.usesPositionalArg()) { 1621 // Cannot mix-and-match positional and non-positional arguments. 1622 S.Diag(getLocationOfByte(CS.getStart()), 1623 diag::warn_format_mix_positional_nonpositional_args) 1624 << getSpecifierRange(startSpecifier, specifierLen); 1625 return false; 1626 } 1627 1628 // Check if the field with is non-zero. 1629 const OptionalAmount &Amt = FS.getFieldWidth(); 1630 if (Amt.getHowSpecified() == OptionalAmount::Constant) { 1631 if (Amt.getConstantAmount() == 0) { 1632 const CharSourceRange &R = getSpecifierRange(Amt.getStart(), 1633 Amt.getConstantLength()); 1634 S.Diag(getLocationOfByte(Amt.getStart()), 1635 diag::warn_scanf_nonzero_width) 1636 << R << FixItHint::CreateRemoval(R); 1637 } 1638 } 1639 1640 if (!FS.consumesDataArgument()) { 1641 // FIXME: Technically specifying a precision or field width here 1642 // makes no sense. Worth issuing a warning at some point. 1643 return true; 1644 } 1645 1646 // Consume the argument. 1647 unsigned argIndex = FS.getArgIndex(); 1648 if (argIndex < NumDataArgs) { 1649 // The check to see if the argIndex is valid will come later. 1650 // We set the bit here because we may exit early from this 1651 // function if we encounter some other error. 1652 CoveredArgs.set(argIndex); 1653 } 1654 1655 // FIXME: Check that the length modifier is valid with the given 1656 // conversion specifier. 1657 1658 // The remaining checks depend on the data arguments. 1659 if (HasVAListArg) 1660 return true; 1661 1662 if (argIndex >= NumDataArgs) { 1663 if (FS.usesPositionalArg()) { 1664 S.Diag(getLocationOfByte(CS.getStart()), 1665 diag::warn_printf_positional_arg_exceeds_data_args) 1666 << (argIndex+1) << NumDataArgs 1667 << getSpecifierRange(startSpecifier, specifierLen); 1668 } 1669 else { 1670 S.Diag(getLocationOfByte(CS.getStart()), 1671 diag::warn_printf_insufficient_data_args) 1672 << getSpecifierRange(startSpecifier, specifierLen); 1673 } 1674 1675 // Don't do any more checking. 1676 return false; 1677 } 1678 1679 // FIXME: Check that the argument type matches the format specifier. 1680 1681 return true; 1682} 1683 1684void Sema::CheckFormatString(const StringLiteral *FExpr, 1685 const Expr *OrigFormatExpr, 1686 const CallExpr *TheCall, bool HasVAListArg, 1687 unsigned format_idx, unsigned firstDataArg, 1688 bool isPrintf) { 1689 1690 // CHECK: is the format string a wide literal? 1691 if (FExpr->isWide()) { 1692 Diag(FExpr->getLocStart(), 1693 diag::warn_format_string_is_wide_literal) 1694 << OrigFormatExpr->getSourceRange(); 1695 return; 1696 } 1697 1698 // Str - The format string. NOTE: this is NOT null-terminated! 1699 const char *Str = FExpr->getStrData(); 1700 1701 // CHECK: empty format string? 1702 unsigned StrLen = FExpr->getByteLength(); 1703 1704 if (StrLen == 0) { 1705 Diag(FExpr->getLocStart(), diag::warn_empty_format_string) 1706 << OrigFormatExpr->getSourceRange(); 1707 return; 1708 } 1709 1710 if (isPrintf) { 1711 CheckPrintfHandler H(*this, FExpr, OrigFormatExpr, firstDataArg, 1712 TheCall->getNumArgs() - firstDataArg, 1713 isa<ObjCStringLiteral>(OrigFormatExpr), Str, 1714 HasVAListArg, TheCall, format_idx); 1715 1716 if (!analyze_format_string::ParsePrintfString(H, Str, Str + StrLen)) 1717 H.DoneProcessing(); 1718 } 1719 else { 1720 CheckScanfHandler H(*this, FExpr, OrigFormatExpr, firstDataArg, 1721 TheCall->getNumArgs() - firstDataArg, 1722 isa<ObjCStringLiteral>(OrigFormatExpr), Str, 1723 HasVAListArg, TheCall, format_idx); 1724 1725 if (!analyze_format_string::ParseScanfString(H, Str, Str + StrLen)) 1726 H.DoneProcessing(); 1727 } 1728} 1729 1730//===--- CHECK: Return Address of Stack Variable --------------------------===// 1731 1732static DeclRefExpr* EvalVal(Expr *E); 1733static DeclRefExpr* EvalAddr(Expr* E); 1734 1735/// CheckReturnStackAddr - Check if a return statement returns the address 1736/// of a stack variable. 1737void 1738Sema::CheckReturnStackAddr(Expr *RetValExp, QualType lhsType, 1739 SourceLocation ReturnLoc) { 1740 1741 // Perform checking for returned stack addresses. 1742 if (lhsType->isPointerType() || lhsType->isBlockPointerType()) { 1743 if (DeclRefExpr *DR = EvalAddr(RetValExp)) 1744 Diag(DR->getLocStart(), diag::warn_ret_stack_addr) 1745 << DR->getDecl()->getDeclName() << RetValExp->getSourceRange(); 1746 1747 // Skip over implicit cast expressions when checking for block expressions. 1748 RetValExp = RetValExp->IgnoreParenCasts(); 1749 1750 if (BlockExpr *C = dyn_cast<BlockExpr>(RetValExp)) 1751 if (C->hasBlockDeclRefExprs()) 1752 Diag(C->getLocStart(), diag::err_ret_local_block) 1753 << C->getSourceRange(); 1754 1755 if (AddrLabelExpr *ALE = dyn_cast<AddrLabelExpr>(RetValExp)) 1756 Diag(ALE->getLocStart(), diag::warn_ret_addr_label) 1757 << ALE->getSourceRange(); 1758 1759 } else if (lhsType->isReferenceType()) { 1760 // Perform checking for stack values returned by reference. 1761 // Check for a reference to the stack 1762 if (DeclRefExpr *DR = EvalVal(RetValExp)) 1763 Diag(DR->getLocStart(), diag::warn_ret_stack_ref) 1764 << DR->getDecl()->getDeclName() << RetValExp->getSourceRange(); 1765 } 1766} 1767 1768/// EvalAddr - EvalAddr and EvalVal are mutually recursive functions that 1769/// check if the expression in a return statement evaluates to an address 1770/// to a location on the stack. The recursion is used to traverse the 1771/// AST of the return expression, with recursion backtracking when we 1772/// encounter a subexpression that (1) clearly does not lead to the address 1773/// of a stack variable or (2) is something we cannot determine leads to 1774/// the address of a stack variable based on such local checking. 1775/// 1776/// EvalAddr processes expressions that are pointers that are used as 1777/// references (and not L-values). EvalVal handles all other values. 1778/// At the base case of the recursion is a check for a DeclRefExpr* in 1779/// the refers to a stack variable. 1780/// 1781/// This implementation handles: 1782/// 1783/// * pointer-to-pointer casts 1784/// * implicit conversions from array references to pointers 1785/// * taking the address of fields 1786/// * arbitrary interplay between "&" and "*" operators 1787/// * pointer arithmetic from an address of a stack variable 1788/// * taking the address of an array element where the array is on the stack 1789static DeclRefExpr* EvalAddr(Expr *E) { 1790 // We should only be called for evaluating pointer expressions. 1791 assert((E->getType()->isAnyPointerType() || 1792 E->getType()->isBlockPointerType() || 1793 E->getType()->isObjCQualifiedIdType()) && 1794 "EvalAddr only works on pointers"); 1795 1796 // Our "symbolic interpreter" is just a dispatch off the currently 1797 // viewed AST node. We then recursively traverse the AST by calling 1798 // EvalAddr and EvalVal appropriately. 1799 switch (E->getStmtClass()) { 1800 case Stmt::ParenExprClass: 1801 // Ignore parentheses. 1802 return EvalAddr(cast<ParenExpr>(E)->getSubExpr()); 1803 1804 case Stmt::UnaryOperatorClass: { 1805 // The only unary operator that make sense to handle here 1806 // is AddrOf. All others don't make sense as pointers. 1807 UnaryOperator *U = cast<UnaryOperator>(E); 1808 1809 if (U->getOpcode() == UnaryOperator::AddrOf) 1810 return EvalVal(U->getSubExpr()); 1811 else 1812 return NULL; 1813 } 1814 1815 case Stmt::BinaryOperatorClass: { 1816 // Handle pointer arithmetic. All other binary operators are not valid 1817 // in this context. 1818 BinaryOperator *B = cast<BinaryOperator>(E); 1819 BinaryOperator::Opcode op = B->getOpcode(); 1820 1821 if (op != BinaryOperator::Add && op != BinaryOperator::Sub) 1822 return NULL; 1823 1824 Expr *Base = B->getLHS(); 1825 1826 // Determine which argument is the real pointer base. It could be 1827 // the RHS argument instead of the LHS. 1828 if (!Base->getType()->isPointerType()) Base = B->getRHS(); 1829 1830 assert (Base->getType()->isPointerType()); 1831 return EvalAddr(Base); 1832 } 1833 1834 // For conditional operators we need to see if either the LHS or RHS are 1835 // valid DeclRefExpr*s. If one of them is valid, we return it. 1836 case Stmt::ConditionalOperatorClass: { 1837 ConditionalOperator *C = cast<ConditionalOperator>(E); 1838 1839 // Handle the GNU extension for missing LHS. 1840 if (Expr *lhsExpr = C->getLHS()) 1841 if (DeclRefExpr* LHS = EvalAddr(lhsExpr)) 1842 return LHS; 1843 1844 return EvalAddr(C->getRHS()); 1845 } 1846 1847 // For casts, we need to handle conversions from arrays to 1848 // pointer values, and pointer-to-pointer conversions. 1849 case Stmt::ImplicitCastExprClass: 1850 case Stmt::CStyleCastExprClass: 1851 case Stmt::CXXFunctionalCastExprClass: { 1852 Expr* SubExpr = cast<CastExpr>(E)->getSubExpr(); 1853 QualType T = SubExpr->getType(); 1854 1855 if (SubExpr->getType()->isPointerType() || 1856 SubExpr->getType()->isBlockPointerType() || 1857 SubExpr->getType()->isObjCQualifiedIdType()) 1858 return EvalAddr(SubExpr); 1859 else if (T->isArrayType()) 1860 return EvalVal(SubExpr); 1861 else 1862 return 0; 1863 } 1864 1865 // C++ casts. For dynamic casts, static casts, and const casts, we 1866 // are always converting from a pointer-to-pointer, so we just blow 1867 // through the cast. In the case the dynamic cast doesn't fail (and 1868 // return NULL), we take the conservative route and report cases 1869 // where we return the address of a stack variable. For Reinterpre 1870 // FIXME: The comment about is wrong; we're not always converting 1871 // from pointer to pointer. I'm guessing that this code should also 1872 // handle references to objects. 1873 case Stmt::CXXStaticCastExprClass: 1874 case Stmt::CXXDynamicCastExprClass: 1875 case Stmt::CXXConstCastExprClass: 1876 case Stmt::CXXReinterpretCastExprClass: { 1877 Expr *S = cast<CXXNamedCastExpr>(E)->getSubExpr(); 1878 if (S->getType()->isPointerType() || S->getType()->isBlockPointerType()) 1879 return EvalAddr(S); 1880 else 1881 return NULL; 1882 } 1883 1884 // Everything else: we simply don't reason about them. 1885 default: 1886 return NULL; 1887 } 1888} 1889 1890 1891/// EvalVal - This function is complements EvalAddr in the mutual recursion. 1892/// See the comments for EvalAddr for more details. 1893static DeclRefExpr* EvalVal(Expr *E) { 1894 1895 // We should only be called for evaluating non-pointer expressions, or 1896 // expressions with a pointer type that are not used as references but instead 1897 // are l-values (e.g., DeclRefExpr with a pointer type). 1898 1899 // Our "symbolic interpreter" is just a dispatch off the currently 1900 // viewed AST node. We then recursively traverse the AST by calling 1901 // EvalAddr and EvalVal appropriately. 1902 switch (E->getStmtClass()) { 1903 case Stmt::DeclRefExprClass: { 1904 // DeclRefExpr: the base case. When we hit a DeclRefExpr we are looking 1905 // at code that refers to a variable's name. We check if it has local 1906 // storage within the function, and if so, return the expression. 1907 DeclRefExpr *DR = cast<DeclRefExpr>(E); 1908 1909 if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl())) 1910 if (V->hasLocalStorage() && !V->getType()->isReferenceType()) return DR; 1911 1912 return NULL; 1913 } 1914 1915 case Stmt::ParenExprClass: 1916 // Ignore parentheses. 1917 return EvalVal(cast<ParenExpr>(E)->getSubExpr()); 1918 1919 case Stmt::UnaryOperatorClass: { 1920 // The only unary operator that make sense to handle here 1921 // is Deref. All others don't resolve to a "name." This includes 1922 // handling all sorts of rvalues passed to a unary operator. 1923 UnaryOperator *U = cast<UnaryOperator>(E); 1924 1925 if (U->getOpcode() == UnaryOperator::Deref) 1926 return EvalAddr(U->getSubExpr()); 1927 1928 return NULL; 1929 } 1930 1931 case Stmt::ArraySubscriptExprClass: { 1932 // Array subscripts are potential references to data on the stack. We 1933 // retrieve the DeclRefExpr* for the array variable if it indeed 1934 // has local storage. 1935 return EvalAddr(cast<ArraySubscriptExpr>(E)->getBase()); 1936 } 1937 1938 case Stmt::ConditionalOperatorClass: { 1939 // For conditional operators we need to see if either the LHS or RHS are 1940 // non-NULL DeclRefExpr's. If one is non-NULL, we return it. 1941 ConditionalOperator *C = cast<ConditionalOperator>(E); 1942 1943 // Handle the GNU extension for missing LHS. 1944 if (Expr *lhsExpr = C->getLHS()) 1945 if (DeclRefExpr *LHS = EvalVal(lhsExpr)) 1946 return LHS; 1947 1948 return EvalVal(C->getRHS()); 1949 } 1950 1951 // Accesses to members are potential references to data on the stack. 1952 case Stmt::MemberExprClass: { 1953 MemberExpr *M = cast<MemberExpr>(E); 1954 1955 // Check for indirect access. We only want direct field accesses. 1956 if (!M->isArrow()) 1957 return EvalVal(M->getBase()); 1958 else 1959 return NULL; 1960 } 1961 1962 // Everything else: we simply don't reason about them. 1963 default: 1964 return NULL; 1965 } 1966} 1967 1968//===--- CHECK: Floating-Point comparisons (-Wfloat-equal) ---------------===// 1969 1970/// Check for comparisons of floating point operands using != and ==. 1971/// Issue a warning if these are no self-comparisons, as they are not likely 1972/// to do what the programmer intended. 1973void Sema::CheckFloatComparison(SourceLocation loc, Expr* lex, Expr *rex) { 1974 bool EmitWarning = true; 1975 1976 Expr* LeftExprSansParen = lex->IgnoreParens(); 1977 Expr* RightExprSansParen = rex->IgnoreParens(); 1978 1979 // Special case: check for x == x (which is OK). 1980 // Do not emit warnings for such cases. 1981 if (DeclRefExpr* DRL = dyn_cast<DeclRefExpr>(LeftExprSansParen)) 1982 if (DeclRefExpr* DRR = dyn_cast<DeclRefExpr>(RightExprSansParen)) 1983 if (DRL->getDecl() == DRR->getDecl()) 1984 EmitWarning = false; 1985 1986 1987 // Special case: check for comparisons against literals that can be exactly 1988 // represented by APFloat. In such cases, do not emit a warning. This 1989 // is a heuristic: often comparison against such literals are used to 1990 // detect if a value in a variable has not changed. This clearly can 1991 // lead to false negatives. 1992 if (EmitWarning) { 1993 if (FloatingLiteral* FLL = dyn_cast<FloatingLiteral>(LeftExprSansParen)) { 1994 if (FLL->isExact()) 1995 EmitWarning = false; 1996 } else 1997 if (FloatingLiteral* FLR = dyn_cast<FloatingLiteral>(RightExprSansParen)){ 1998 if (FLR->isExact()) 1999 EmitWarning = false; 2000 } 2001 } 2002 2003 // Check for comparisons with builtin types. 2004 if (EmitWarning) 2005 if (CallExpr* CL = dyn_cast<CallExpr>(LeftExprSansParen)) 2006 if (CL->isBuiltinCall(Context)) 2007 EmitWarning = false; 2008 2009 if (EmitWarning) 2010 if (CallExpr* CR = dyn_cast<CallExpr>(RightExprSansParen)) 2011 if (CR->isBuiltinCall(Context)) 2012 EmitWarning = false; 2013 2014 // Emit the diagnostic. 2015 if (EmitWarning) 2016 Diag(loc, diag::warn_floatingpoint_eq) 2017 << lex->getSourceRange() << rex->getSourceRange(); 2018} 2019 2020//===--- CHECK: Integer mixed-sign comparisons (-Wsign-compare) --------===// 2021//===--- CHECK: Lossy implicit conversions (-Wconversion) --------------===// 2022 2023namespace { 2024 2025/// Structure recording the 'active' range of an integer-valued 2026/// expression. 2027struct IntRange { 2028 /// The number of bits active in the int. 2029 unsigned Width; 2030 2031 /// True if the int is known not to have negative values. 2032 bool NonNegative; 2033 2034 IntRange() {} 2035 IntRange(unsigned Width, bool NonNegative) 2036 : Width(Width), NonNegative(NonNegative) 2037 {} 2038 2039 // Returns the range of the bool type. 2040 static IntRange forBoolType() { 2041 return IntRange(1, true); 2042 } 2043 2044 // Returns the range of an integral type. 2045 static IntRange forType(ASTContext &C, QualType T) { 2046 return forCanonicalType(C, T->getCanonicalTypeInternal().getTypePtr()); 2047 } 2048 2049 // Returns the range of an integeral type based on its canonical 2050 // representation. 2051 static IntRange forCanonicalType(ASTContext &C, const Type *T) { 2052 assert(T->isCanonicalUnqualified()); 2053 2054 if (const VectorType *VT = dyn_cast<VectorType>(T)) 2055 T = VT->getElementType().getTypePtr(); 2056 if (const ComplexType *CT = dyn_cast<ComplexType>(T)) 2057 T = CT->getElementType().getTypePtr(); 2058 2059 if (const EnumType *ET = dyn_cast<EnumType>(T)) { 2060 EnumDecl *Enum = ET->getDecl(); 2061 unsigned NumPositive = Enum->getNumPositiveBits(); 2062 unsigned NumNegative = Enum->getNumNegativeBits(); 2063 2064 return IntRange(std::max(NumPositive, NumNegative), NumNegative == 0); 2065 } 2066 2067 const BuiltinType *BT = cast<BuiltinType>(T); 2068 assert(BT->isInteger()); 2069 2070 return IntRange(C.getIntWidth(QualType(T, 0)), BT->isUnsignedInteger()); 2071 } 2072 2073 // Returns the supremum of two ranges: i.e. their conservative merge. 2074 static IntRange join(IntRange L, IntRange R) { 2075 return IntRange(std::max(L.Width, R.Width), 2076 L.NonNegative && R.NonNegative); 2077 } 2078 2079 // Returns the infinum of two ranges: i.e. their aggressive merge. 2080 static IntRange meet(IntRange L, IntRange R) { 2081 return IntRange(std::min(L.Width, R.Width), 2082 L.NonNegative || R.NonNegative); 2083 } 2084}; 2085 2086IntRange GetValueRange(ASTContext &C, llvm::APSInt &value, unsigned MaxWidth) { 2087 if (value.isSigned() && value.isNegative()) 2088 return IntRange(value.getMinSignedBits(), false); 2089 2090 if (value.getBitWidth() > MaxWidth) 2091 value.trunc(MaxWidth); 2092 2093 // isNonNegative() just checks the sign bit without considering 2094 // signedness. 2095 return IntRange(value.getActiveBits(), true); 2096} 2097 2098IntRange GetValueRange(ASTContext &C, APValue &result, QualType Ty, 2099 unsigned MaxWidth) { 2100 if (result.isInt()) 2101 return GetValueRange(C, result.getInt(), MaxWidth); 2102 2103 if (result.isVector()) { 2104 IntRange R = GetValueRange(C, result.getVectorElt(0), Ty, MaxWidth); 2105 for (unsigned i = 1, e = result.getVectorLength(); i != e; ++i) { 2106 IntRange El = GetValueRange(C, result.getVectorElt(i), Ty, MaxWidth); 2107 R = IntRange::join(R, El); 2108 } 2109 return R; 2110 } 2111 2112 if (result.isComplexInt()) { 2113 IntRange R = GetValueRange(C, result.getComplexIntReal(), MaxWidth); 2114 IntRange I = GetValueRange(C, result.getComplexIntImag(), MaxWidth); 2115 return IntRange::join(R, I); 2116 } 2117 2118 // This can happen with lossless casts to intptr_t of "based" lvalues. 2119 // Assume it might use arbitrary bits. 2120 // FIXME: The only reason we need to pass the type in here is to get 2121 // the sign right on this one case. It would be nice if APValue 2122 // preserved this. 2123 assert(result.isLValue()); 2124 return IntRange(MaxWidth, Ty->isUnsignedIntegerType()); 2125} 2126 2127/// Pseudo-evaluate the given integer expression, estimating the 2128/// range of values it might take. 2129/// 2130/// \param MaxWidth - the width to which the value will be truncated 2131IntRange GetExprRange(ASTContext &C, Expr *E, unsigned MaxWidth) { 2132 E = E->IgnoreParens(); 2133 2134 // Try a full evaluation first. 2135 Expr::EvalResult result; 2136 if (E->Evaluate(result, C)) 2137 return GetValueRange(C, result.Val, E->getType(), MaxWidth); 2138 2139 // I think we only want to look through implicit casts here; if the 2140 // user has an explicit widening cast, we should treat the value as 2141 // being of the new, wider type. 2142 if (ImplicitCastExpr *CE = dyn_cast<ImplicitCastExpr>(E)) { 2143 if (CE->getCastKind() == CastExpr::CK_NoOp) 2144 return GetExprRange(C, CE->getSubExpr(), MaxWidth); 2145 2146 IntRange OutputTypeRange = IntRange::forType(C, CE->getType()); 2147 2148 bool isIntegerCast = (CE->getCastKind() == CastExpr::CK_IntegralCast); 2149 if (!isIntegerCast && CE->getCastKind() == CastExpr::CK_Unknown) 2150 isIntegerCast = CE->getSubExpr()->getType()->isIntegerType(); 2151 2152 // Assume that non-integer casts can span the full range of the type. 2153 if (!isIntegerCast) 2154 return OutputTypeRange; 2155 2156 IntRange SubRange 2157 = GetExprRange(C, CE->getSubExpr(), 2158 std::min(MaxWidth, OutputTypeRange.Width)); 2159 2160 // Bail out if the subexpr's range is as wide as the cast type. 2161 if (SubRange.Width >= OutputTypeRange.Width) 2162 return OutputTypeRange; 2163 2164 // Otherwise, we take the smaller width, and we're non-negative if 2165 // either the output type or the subexpr is. 2166 return IntRange(SubRange.Width, 2167 SubRange.NonNegative || OutputTypeRange.NonNegative); 2168 } 2169 2170 if (ConditionalOperator *CO = dyn_cast<ConditionalOperator>(E)) { 2171 // If we can fold the condition, just take that operand. 2172 bool CondResult; 2173 if (CO->getCond()->EvaluateAsBooleanCondition(CondResult, C)) 2174 return GetExprRange(C, CondResult ? CO->getTrueExpr() 2175 : CO->getFalseExpr(), 2176 MaxWidth); 2177 2178 // Otherwise, conservatively merge. 2179 IntRange L = GetExprRange(C, CO->getTrueExpr(), MaxWidth); 2180 IntRange R = GetExprRange(C, CO->getFalseExpr(), MaxWidth); 2181 return IntRange::join(L, R); 2182 } 2183 2184 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) { 2185 switch (BO->getOpcode()) { 2186 2187 // Boolean-valued operations are single-bit and positive. 2188 case BinaryOperator::LAnd: 2189 case BinaryOperator::LOr: 2190 case BinaryOperator::LT: 2191 case BinaryOperator::GT: 2192 case BinaryOperator::LE: 2193 case BinaryOperator::GE: 2194 case BinaryOperator::EQ: 2195 case BinaryOperator::NE: 2196 return IntRange::forBoolType(); 2197 2198 // The type of these compound assignments is the type of the LHS, 2199 // so the RHS is not necessarily an integer. 2200 case BinaryOperator::MulAssign: 2201 case BinaryOperator::DivAssign: 2202 case BinaryOperator::RemAssign: 2203 case BinaryOperator::AddAssign: 2204 case BinaryOperator::SubAssign: 2205 return IntRange::forType(C, E->getType()); 2206 2207 // Operations with opaque sources are black-listed. 2208 case BinaryOperator::PtrMemD: 2209 case BinaryOperator::PtrMemI: 2210 return IntRange::forType(C, E->getType()); 2211 2212 // Bitwise-and uses the *infinum* of the two source ranges. 2213 case BinaryOperator::And: 2214 case BinaryOperator::AndAssign: 2215 return IntRange::meet(GetExprRange(C, BO->getLHS(), MaxWidth), 2216 GetExprRange(C, BO->getRHS(), MaxWidth)); 2217 2218 // Left shift gets black-listed based on a judgement call. 2219 case BinaryOperator::Shl: 2220 // ...except that we want to treat '1 << (blah)' as logically 2221 // positive. It's an important idiom. 2222 if (IntegerLiteral *I 2223 = dyn_cast<IntegerLiteral>(BO->getLHS()->IgnoreParenCasts())) { 2224 if (I->getValue() == 1) { 2225 IntRange R = IntRange::forType(C, E->getType()); 2226 return IntRange(R.Width, /*NonNegative*/ true); 2227 } 2228 } 2229 // fallthrough 2230 2231 case BinaryOperator::ShlAssign: 2232 return IntRange::forType(C, E->getType()); 2233 2234 // Right shift by a constant can narrow its left argument. 2235 case BinaryOperator::Shr: 2236 case BinaryOperator::ShrAssign: { 2237 IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth); 2238 2239 // If the shift amount is a positive constant, drop the width by 2240 // that much. 2241 llvm::APSInt shift; 2242 if (BO->getRHS()->isIntegerConstantExpr(shift, C) && 2243 shift.isNonNegative()) { 2244 unsigned zext = shift.getZExtValue(); 2245 if (zext >= L.Width) 2246 L.Width = (L.NonNegative ? 0 : 1); 2247 else 2248 L.Width -= zext; 2249 } 2250 2251 return L; 2252 } 2253 2254 // Comma acts as its right operand. 2255 case BinaryOperator::Comma: 2256 return GetExprRange(C, BO->getRHS(), MaxWidth); 2257 2258 // Black-list pointer subtractions. 2259 case BinaryOperator::Sub: 2260 if (BO->getLHS()->getType()->isPointerType()) 2261 return IntRange::forType(C, E->getType()); 2262 // fallthrough 2263 2264 default: 2265 break; 2266 } 2267 2268 // Treat every other operator as if it were closed on the 2269 // narrowest type that encompasses both operands. 2270 IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth); 2271 IntRange R = GetExprRange(C, BO->getRHS(), MaxWidth); 2272 return IntRange::join(L, R); 2273 } 2274 2275 if (UnaryOperator *UO = dyn_cast<UnaryOperator>(E)) { 2276 switch (UO->getOpcode()) { 2277 // Boolean-valued operations are white-listed. 2278 case UnaryOperator::LNot: 2279 return IntRange::forBoolType(); 2280 2281 // Operations with opaque sources are black-listed. 2282 case UnaryOperator::Deref: 2283 case UnaryOperator::AddrOf: // should be impossible 2284 case UnaryOperator::OffsetOf: 2285 return IntRange::forType(C, E->getType()); 2286 2287 default: 2288 return GetExprRange(C, UO->getSubExpr(), MaxWidth); 2289 } 2290 } 2291 2292 if (dyn_cast<OffsetOfExpr>(E)) { 2293 IntRange::forType(C, E->getType()); 2294 } 2295 2296 FieldDecl *BitField = E->getBitField(); 2297 if (BitField) { 2298 llvm::APSInt BitWidthAP = BitField->getBitWidth()->EvaluateAsInt(C); 2299 unsigned BitWidth = BitWidthAP.getZExtValue(); 2300 2301 return IntRange(BitWidth, BitField->getType()->isUnsignedIntegerType()); 2302 } 2303 2304 return IntRange::forType(C, E->getType()); 2305} 2306 2307IntRange GetExprRange(ASTContext &C, Expr *E) { 2308 return GetExprRange(C, E, C.getIntWidth(E->getType())); 2309} 2310 2311/// Checks whether the given value, which currently has the given 2312/// source semantics, has the same value when coerced through the 2313/// target semantics. 2314bool IsSameFloatAfterCast(const llvm::APFloat &value, 2315 const llvm::fltSemantics &Src, 2316 const llvm::fltSemantics &Tgt) { 2317 llvm::APFloat truncated = value; 2318 2319 bool ignored; 2320 truncated.convert(Src, llvm::APFloat::rmNearestTiesToEven, &ignored); 2321 truncated.convert(Tgt, llvm::APFloat::rmNearestTiesToEven, &ignored); 2322 2323 return truncated.bitwiseIsEqual(value); 2324} 2325 2326/// Checks whether the given value, which currently has the given 2327/// source semantics, has the same value when coerced through the 2328/// target semantics. 2329/// 2330/// The value might be a vector of floats (or a complex number). 2331bool IsSameFloatAfterCast(const APValue &value, 2332 const llvm::fltSemantics &Src, 2333 const llvm::fltSemantics &Tgt) { 2334 if (value.isFloat()) 2335 return IsSameFloatAfterCast(value.getFloat(), Src, Tgt); 2336 2337 if (value.isVector()) { 2338 for (unsigned i = 0, e = value.getVectorLength(); i != e; ++i) 2339 if (!IsSameFloatAfterCast(value.getVectorElt(i), Src, Tgt)) 2340 return false; 2341 return true; 2342 } 2343 2344 assert(value.isComplexFloat()); 2345 return (IsSameFloatAfterCast(value.getComplexFloatReal(), Src, Tgt) && 2346 IsSameFloatAfterCast(value.getComplexFloatImag(), Src, Tgt)); 2347} 2348 2349void AnalyzeImplicitConversions(Sema &S, Expr *E); 2350 2351bool IsZero(Sema &S, Expr *E) { 2352 llvm::APSInt Value; 2353 return E->isIntegerConstantExpr(Value, S.Context) && Value == 0; 2354} 2355 2356void CheckTrivialUnsignedComparison(Sema &S, BinaryOperator *E) { 2357 BinaryOperator::Opcode op = E->getOpcode(); 2358 if (op == BinaryOperator::LT && IsZero(S, E->getRHS())) { 2359 S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison) 2360 << "< 0" << "false" 2361 << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); 2362 } else if (op == BinaryOperator::GE && IsZero(S, E->getRHS())) { 2363 S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison) 2364 << ">= 0" << "true" 2365 << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); 2366 } else if (op == BinaryOperator::GT && IsZero(S, E->getLHS())) { 2367 S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison) 2368 << "0 >" << "false" 2369 << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); 2370 } else if (op == BinaryOperator::LE && IsZero(S, E->getLHS())) { 2371 S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison) 2372 << "0 <=" << "true" 2373 << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); 2374 } 2375} 2376 2377/// Analyze the operands of the given comparison. Implements the 2378/// fallback case from AnalyzeComparison. 2379void AnalyzeImpConvsInComparison(Sema &S, BinaryOperator *E) { 2380 AnalyzeImplicitConversions(S, E->getLHS()); 2381 AnalyzeImplicitConversions(S, E->getRHS()); 2382} 2383 2384/// \brief Implements -Wsign-compare. 2385/// 2386/// \param lex the left-hand expression 2387/// \param rex the right-hand expression 2388/// \param OpLoc the location of the joining operator 2389/// \param BinOpc binary opcode or 0 2390void AnalyzeComparison(Sema &S, BinaryOperator *E) { 2391 // The type the comparison is being performed in. 2392 QualType T = E->getLHS()->getType(); 2393 assert(S.Context.hasSameUnqualifiedType(T, E->getRHS()->getType()) 2394 && "comparison with mismatched types"); 2395 2396 // We don't do anything special if this isn't an unsigned integral 2397 // comparison: we're only interested in integral comparisons, and 2398 // signed comparisons only happen in cases we don't care to warn about. 2399 if (!T->isUnsignedIntegerType()) 2400 return AnalyzeImpConvsInComparison(S, E); 2401 2402 Expr *lex = E->getLHS()->IgnoreParenImpCasts(); 2403 Expr *rex = E->getRHS()->IgnoreParenImpCasts(); 2404 2405 // Check to see if one of the (unmodified) operands is of different 2406 // signedness. 2407 Expr *signedOperand, *unsignedOperand; 2408 if (lex->getType()->isSignedIntegerType()) { 2409 assert(!rex->getType()->isSignedIntegerType() && 2410 "unsigned comparison between two signed integer expressions?"); 2411 signedOperand = lex; 2412 unsignedOperand = rex; 2413 } else if (rex->getType()->isSignedIntegerType()) { 2414 signedOperand = rex; 2415 unsignedOperand = lex; 2416 } else { 2417 CheckTrivialUnsignedComparison(S, E); 2418 return AnalyzeImpConvsInComparison(S, E); 2419 } 2420 2421 // Otherwise, calculate the effective range of the signed operand. 2422 IntRange signedRange = GetExprRange(S.Context, signedOperand); 2423 2424 // Go ahead and analyze implicit conversions in the operands. Note 2425 // that we skip the implicit conversions on both sides. 2426 AnalyzeImplicitConversions(S, lex); 2427 AnalyzeImplicitConversions(S, rex); 2428 2429 // If the signed range is non-negative, -Wsign-compare won't fire, 2430 // but we should still check for comparisons which are always true 2431 // or false. 2432 if (signedRange.NonNegative) 2433 return CheckTrivialUnsignedComparison(S, E); 2434 2435 // For (in)equality comparisons, if the unsigned operand is a 2436 // constant which cannot collide with a overflowed signed operand, 2437 // then reinterpreting the signed operand as unsigned will not 2438 // change the result of the comparison. 2439 if (E->isEqualityOp()) { 2440 unsigned comparisonWidth = S.Context.getIntWidth(T); 2441 IntRange unsignedRange = GetExprRange(S.Context, unsignedOperand); 2442 2443 // We should never be unable to prove that the unsigned operand is 2444 // non-negative. 2445 assert(unsignedRange.NonNegative && "unsigned range includes negative?"); 2446 2447 if (unsignedRange.Width < comparisonWidth) 2448 return; 2449 } 2450 2451 S.Diag(E->getOperatorLoc(), diag::warn_mixed_sign_comparison) 2452 << lex->getType() << rex->getType() 2453 << lex->getSourceRange() << rex->getSourceRange(); 2454} 2455 2456/// Diagnose an implicit cast; purely a helper for CheckImplicitConversion. 2457void DiagnoseImpCast(Sema &S, Expr *E, QualType T, unsigned diag) { 2458 S.Diag(E->getExprLoc(), diag) << E->getType() << T << E->getSourceRange(); 2459} 2460 2461void CheckImplicitConversion(Sema &S, Expr *E, QualType T, 2462 bool *ICContext = 0) { 2463 if (E->isTypeDependent() || E->isValueDependent()) return; 2464 2465 const Type *Source = S.Context.getCanonicalType(E->getType()).getTypePtr(); 2466 const Type *Target = S.Context.getCanonicalType(T).getTypePtr(); 2467 if (Source == Target) return; 2468 if (Target->isDependentType()) return; 2469 2470 // Never diagnose implicit casts to bool. 2471 if (Target->isSpecificBuiltinType(BuiltinType::Bool)) 2472 return; 2473 2474 // Strip vector types. 2475 if (isa<VectorType>(Source)) { 2476 if (!isa<VectorType>(Target)) 2477 return DiagnoseImpCast(S, E, T, diag::warn_impcast_vector_scalar); 2478 2479 Source = cast<VectorType>(Source)->getElementType().getTypePtr(); 2480 Target = cast<VectorType>(Target)->getElementType().getTypePtr(); 2481 } 2482 2483 // Strip complex types. 2484 if (isa<ComplexType>(Source)) { 2485 if (!isa<ComplexType>(Target)) 2486 return DiagnoseImpCast(S, E, T, diag::warn_impcast_complex_scalar); 2487 2488 Source = cast<ComplexType>(Source)->getElementType().getTypePtr(); 2489 Target = cast<ComplexType>(Target)->getElementType().getTypePtr(); 2490 } 2491 2492 const BuiltinType *SourceBT = dyn_cast<BuiltinType>(Source); 2493 const BuiltinType *TargetBT = dyn_cast<BuiltinType>(Target); 2494 2495 // If the source is floating point... 2496 if (SourceBT && SourceBT->isFloatingPoint()) { 2497 // ...and the target is floating point... 2498 if (TargetBT && TargetBT->isFloatingPoint()) { 2499 // ...then warn if we're dropping FP rank. 2500 2501 // Builtin FP kinds are ordered by increasing FP rank. 2502 if (SourceBT->getKind() > TargetBT->getKind()) { 2503 // Don't warn about float constants that are precisely 2504 // representable in the target type. 2505 Expr::EvalResult result; 2506 if (E->Evaluate(result, S.Context)) { 2507 // Value might be a float, a float vector, or a float complex. 2508 if (IsSameFloatAfterCast(result.Val, 2509 S.Context.getFloatTypeSemantics(QualType(TargetBT, 0)), 2510 S.Context.getFloatTypeSemantics(QualType(SourceBT, 0)))) 2511 return; 2512 } 2513 2514 DiagnoseImpCast(S, E, T, diag::warn_impcast_float_precision); 2515 } 2516 return; 2517 } 2518 2519 // If the target is integral, always warn. 2520 if ((TargetBT && TargetBT->isInteger())) 2521 // TODO: don't warn for integer values? 2522 DiagnoseImpCast(S, E, T, diag::warn_impcast_float_integer); 2523 2524 return; 2525 } 2526 2527 if (!Source->isIntegerType() || !Target->isIntegerType()) 2528 return; 2529 2530 IntRange SourceRange = GetExprRange(S.Context, E); 2531 IntRange TargetRange = IntRange::forCanonicalType(S.Context, Target); 2532 2533 if (SourceRange.Width > TargetRange.Width) { 2534 // People want to build with -Wshorten-64-to-32 and not -Wconversion 2535 // and by god we'll let them. 2536 if (SourceRange.Width == 64 && TargetRange.Width == 32) 2537 return DiagnoseImpCast(S, E, T, diag::warn_impcast_integer_64_32); 2538 return DiagnoseImpCast(S, E, T, diag::warn_impcast_integer_precision); 2539 } 2540 2541 if ((TargetRange.NonNegative && !SourceRange.NonNegative) || 2542 (!TargetRange.NonNegative && SourceRange.NonNegative && 2543 SourceRange.Width == TargetRange.Width)) { 2544 unsigned DiagID = diag::warn_impcast_integer_sign; 2545 2546 // Traditionally, gcc has warned about this under -Wsign-compare. 2547 // We also want to warn about it in -Wconversion. 2548 // So if -Wconversion is off, use a completely identical diagnostic 2549 // in the sign-compare group. 2550 // The conditional-checking code will 2551 if (ICContext) { 2552 DiagID = diag::warn_impcast_integer_sign_conditional; 2553 *ICContext = true; 2554 } 2555 2556 return DiagnoseImpCast(S, E, T, DiagID); 2557 } 2558 2559 return; 2560} 2561 2562void CheckConditionalOperator(Sema &S, ConditionalOperator *E, QualType T); 2563 2564void CheckConditionalOperand(Sema &S, Expr *E, QualType T, 2565 bool &ICContext) { 2566 E = E->IgnoreParenImpCasts(); 2567 2568 if (isa<ConditionalOperator>(E)) 2569 return CheckConditionalOperator(S, cast<ConditionalOperator>(E), T); 2570 2571 AnalyzeImplicitConversions(S, E); 2572 if (E->getType() != T) 2573 return CheckImplicitConversion(S, E, T, &ICContext); 2574 return; 2575} 2576 2577void CheckConditionalOperator(Sema &S, ConditionalOperator *E, QualType T) { 2578 AnalyzeImplicitConversions(S, E->getCond()); 2579 2580 bool Suspicious = false; 2581 CheckConditionalOperand(S, E->getTrueExpr(), T, Suspicious); 2582 CheckConditionalOperand(S, E->getFalseExpr(), T, Suspicious); 2583 2584 // If -Wconversion would have warned about either of the candidates 2585 // for a signedness conversion to the context type... 2586 if (!Suspicious) return; 2587 2588 // ...but it's currently ignored... 2589 if (S.Diags.getDiagnosticLevel(diag::warn_impcast_integer_sign_conditional)) 2590 return; 2591 2592 // ...and -Wsign-compare isn't... 2593 if (!S.Diags.getDiagnosticLevel(diag::warn_mixed_sign_conditional)) 2594 return; 2595 2596 // ...then check whether it would have warned about either of the 2597 // candidates for a signedness conversion to the condition type. 2598 if (E->getType() != T) { 2599 Suspicious = false; 2600 CheckImplicitConversion(S, E->getTrueExpr()->IgnoreParenImpCasts(), 2601 E->getType(), &Suspicious); 2602 if (!Suspicious) 2603 CheckImplicitConversion(S, E->getFalseExpr()->IgnoreParenImpCasts(), 2604 E->getType(), &Suspicious); 2605 if (!Suspicious) 2606 return; 2607 } 2608 2609 // If so, emit a diagnostic under -Wsign-compare. 2610 Expr *lex = E->getTrueExpr()->IgnoreParenImpCasts(); 2611 Expr *rex = E->getFalseExpr()->IgnoreParenImpCasts(); 2612 S.Diag(E->getQuestionLoc(), diag::warn_mixed_sign_conditional) 2613 << lex->getType() << rex->getType() 2614 << lex->getSourceRange() << rex->getSourceRange(); 2615} 2616 2617/// AnalyzeImplicitConversions - Find and report any interesting 2618/// implicit conversions in the given expression. There are a couple 2619/// of competing diagnostics here, -Wconversion and -Wsign-compare. 2620void AnalyzeImplicitConversions(Sema &S, Expr *OrigE) { 2621 QualType T = OrigE->getType(); 2622 Expr *E = OrigE->IgnoreParenImpCasts(); 2623 2624 // For conditional operators, we analyze the arguments as if they 2625 // were being fed directly into the output. 2626 if (isa<ConditionalOperator>(E)) { 2627 ConditionalOperator *CO = cast<ConditionalOperator>(E); 2628 CheckConditionalOperator(S, CO, T); 2629 return; 2630 } 2631 2632 // Go ahead and check any implicit conversions we might have skipped. 2633 // The non-canonical typecheck is just an optimization; 2634 // CheckImplicitConversion will filter out dead implicit conversions. 2635 if (E->getType() != T) 2636 CheckImplicitConversion(S, E, T); 2637 2638 // Now continue drilling into this expression. 2639 2640 // Skip past explicit casts. 2641 if (isa<ExplicitCastExpr>(E)) { 2642 E = cast<ExplicitCastExpr>(E)->getSubExpr()->IgnoreParenImpCasts(); 2643 return AnalyzeImplicitConversions(S, E); 2644 } 2645 2646 // Do a somewhat different check with comparison operators. 2647 if (isa<BinaryOperator>(E) && cast<BinaryOperator>(E)->isComparisonOp()) 2648 return AnalyzeComparison(S, cast<BinaryOperator>(E)); 2649 2650 // These break the otherwise-useful invariant below. Fortunately, 2651 // we don't really need to recurse into them, because any internal 2652 // expressions should have been analyzed already when they were 2653 // built into statements. 2654 if (isa<StmtExpr>(E)) return; 2655 2656 // Don't descend into unevaluated contexts. 2657 if (isa<SizeOfAlignOfExpr>(E)) return; 2658 2659 // Now just recurse over the expression's children. 2660 for (Stmt::child_iterator I = E->child_begin(), IE = E->child_end(); 2661 I != IE; ++I) 2662 AnalyzeImplicitConversions(S, cast<Expr>(*I)); 2663} 2664 2665} // end anonymous namespace 2666 2667/// Diagnoses "dangerous" implicit conversions within the given 2668/// expression (which is a full expression). Implements -Wconversion 2669/// and -Wsign-compare. 2670void Sema::CheckImplicitConversions(Expr *E) { 2671 // Don't diagnose in unevaluated contexts. 2672 if (ExprEvalContexts.back().Context == Sema::Unevaluated) 2673 return; 2674 2675 // Don't diagnose for value- or type-dependent expressions. 2676 if (E->isTypeDependent() || E->isValueDependent()) 2677 return; 2678 2679 AnalyzeImplicitConversions(*this, E); 2680} 2681 2682/// CheckParmsForFunctionDef - Check that the parameters of the given 2683/// function are appropriate for the definition of a function. This 2684/// takes care of any checks that cannot be performed on the 2685/// declaration itself, e.g., that the types of each of the function 2686/// parameters are complete. 2687bool Sema::CheckParmsForFunctionDef(FunctionDecl *FD) { 2688 bool HasInvalidParm = false; 2689 for (unsigned p = 0, NumParams = FD->getNumParams(); p < NumParams; ++p) { 2690 ParmVarDecl *Param = FD->getParamDecl(p); 2691 2692 // C99 6.7.5.3p4: the parameters in a parameter type list in a 2693 // function declarator that is part of a function definition of 2694 // that function shall not have incomplete type. 2695 // 2696 // This is also C++ [dcl.fct]p6. 2697 if (!Param->isInvalidDecl() && 2698 RequireCompleteType(Param->getLocation(), Param->getType(), 2699 diag::err_typecheck_decl_incomplete_type)) { 2700 Param->setInvalidDecl(); 2701 HasInvalidParm = true; 2702 } 2703 2704 // C99 6.9.1p5: If the declarator includes a parameter type list, the 2705 // declaration of each parameter shall include an identifier. 2706 if (Param->getIdentifier() == 0 && 2707 !Param->isImplicit() && 2708 !getLangOptions().CPlusPlus) 2709 Diag(Param->getLocation(), diag::err_parameter_name_omitted); 2710 2711 // C99 6.7.5.3p12: 2712 // If the function declarator is not part of a definition of that 2713 // function, parameters may have incomplete type and may use the [*] 2714 // notation in their sequences of declarator specifiers to specify 2715 // variable length array types. 2716 QualType PType = Param->getOriginalType(); 2717 if (const ArrayType *AT = Context.getAsArrayType(PType)) { 2718 if (AT->getSizeModifier() == ArrayType::Star) { 2719 // FIXME: This diagnosic should point the the '[*]' if source-location 2720 // information is added for it. 2721 Diag(Param->getLocation(), diag::err_array_star_in_function_definition); 2722 } 2723 } 2724 } 2725 2726 return HasInvalidParm; 2727} 2728