SemaChecking.cpp revision e4ee9663168dfb2b4122c768091e30217328c9fa
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/PrintfFormatString.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 if (SemaBuiltinAtomicOverloaded(TheCall)) 206 return ExprError(); 207 break; 208 } 209 210 // Since the target specific builtins for each arch overlap, only check those 211 // of the arch we are compiling for. 212 if (BuiltinID >= Builtin::FirstTSBuiltin) { 213 switch (Context.Target.getTriple().getArch()) { 214 case llvm::Triple::arm: 215 case llvm::Triple::thumb: 216 if (CheckARMBuiltinFunctionCall(BuiltinID, TheCall)) 217 return ExprError(); 218 break; 219 case llvm::Triple::x86: 220 case llvm::Triple::x86_64: 221 if (CheckX86BuiltinFunctionCall(BuiltinID, TheCall)) 222 return ExprError(); 223 break; 224 default: 225 break; 226 } 227 } 228 229 return move(TheCallResult); 230} 231 232bool Sema::CheckX86BuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) { 233 switch (BuiltinID) { 234 case X86::BI__builtin_ia32_palignr128: 235 case X86::BI__builtin_ia32_palignr: { 236 llvm::APSInt Result; 237 if (SemaBuiltinConstantArg(TheCall, 2, Result)) 238 return true; 239 break; 240 } 241 } 242 return false; 243} 244 245// Get the valid immediate range for the specified NEON type code. 246static unsigned RFT(unsigned t, bool shift = false) { 247 bool quad = t & 0x10; 248 249 switch (t & 0x7) { 250 case 0: // i8 251 return shift ? 7 : (8 << (int)quad) - 1; 252 case 1: // i16 253 return shift ? 15 : (4 << (int)quad) - 1; 254 case 2: // i32 255 return shift ? 31 : (2 << (int)quad) - 1; 256 case 3: // i64 257 return shift ? 63 : (1 << (int)quad) - 1; 258 case 4: // f32 259 assert(!shift && "cannot shift float types!"); 260 return (2 << (int)quad) - 1; 261 case 5: // poly8 262 assert(!shift && "cannot shift polynomial types!"); 263 return (8 << (int)quad) - 1; 264 case 6: // poly16 265 assert(!shift && "cannot shift polynomial types!"); 266 return (4 << (int)quad) - 1; 267 case 7: // float16 268 assert(!shift && "cannot shift float types!"); 269 return (4 << (int)quad) - 1; 270 } 271 return 0; 272} 273 274bool Sema::CheckARMBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) { 275 llvm::APSInt Result; 276 277 unsigned mask = 0; 278 unsigned TV = 0; 279 switch (BuiltinID) { 280#define GET_NEON_OVERLOAD_CHECK 281#include "clang/Basic/arm_neon.inc" 282#undef GET_NEON_OVERLOAD_CHECK 283 } 284 285 // For NEON intrinsics which are overloaded on vector element type, validate 286 // the immediate which specifies which variant to emit. 287 if (mask) { 288 unsigned ArgNo = TheCall->getNumArgs()-1; 289 if (SemaBuiltinConstantArg(TheCall, ArgNo, Result)) 290 return true; 291 292 TV = Result.getLimitedValue(32); 293 if ((TV > 31) || (mask & (1 << TV)) == 0) 294 return Diag(TheCall->getLocStart(), diag::err_invalid_neon_type_code) 295 << TheCall->getArg(ArgNo)->getSourceRange(); 296 } 297 298 // For NEON intrinsics which take an immediate value as part of the 299 // instruction, range check them here. 300 unsigned i = 0, l = 0, u = 0; 301 switch (BuiltinID) { 302 default: return false; 303#define GET_NEON_IMMEDIATE_CHECK 304#include "clang/Basic/arm_neon.inc" 305#undef GET_NEON_IMMEDIATE_CHECK 306 }; 307 308 // Check that the immediate argument is actually a constant. 309 if (SemaBuiltinConstantArg(TheCall, i, Result)) 310 return true; 311 312 // Range check against the upper/lower values for this isntruction. 313 unsigned Val = Result.getZExtValue(); 314 if (Val < l || Val > (u + l)) 315 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 316 << llvm::utostr(l) << llvm::utostr(u+l) 317 << TheCall->getArg(i)->getSourceRange(); 318 319 return false; 320} 321 322/// CheckFunctionCall - Check a direct function call for various correctness 323/// and safety properties not strictly enforced by the C type system. 324bool Sema::CheckFunctionCall(FunctionDecl *FDecl, CallExpr *TheCall) { 325 // Get the IdentifierInfo* for the called function. 326 IdentifierInfo *FnInfo = FDecl->getIdentifier(); 327 328 // None of the checks below are needed for functions that don't have 329 // simple names (e.g., C++ conversion functions). 330 if (!FnInfo) 331 return false; 332 333 // FIXME: This mechanism should be abstracted to be less fragile and 334 // more efficient. For example, just map function ids to custom 335 // handlers. 336 337 // Printf checking. 338 if (const FormatAttr *Format = FDecl->getAttr<FormatAttr>()) { 339 if (CheckablePrintfAttr(Format, TheCall)) { 340 bool HasVAListArg = Format->getFirstArg() == 0; 341 CheckPrintfArguments(TheCall, HasVAListArg, Format->getFormatIdx() - 1, 342 HasVAListArg ? 0 : Format->getFirstArg() - 1); 343 } 344 } 345 346 for (const NonNullAttr *NonNull = FDecl->getAttr<NonNullAttr>(); NonNull; 347 NonNull = NonNull->getNext<NonNullAttr>()) 348 CheckNonNullArguments(NonNull, TheCall); 349 350 return false; 351} 352 353bool Sema::CheckBlockCall(NamedDecl *NDecl, CallExpr *TheCall) { 354 // Printf checking. 355 const FormatAttr *Format = NDecl->getAttr<FormatAttr>(); 356 if (!Format) 357 return false; 358 359 const VarDecl *V = dyn_cast<VarDecl>(NDecl); 360 if (!V) 361 return false; 362 363 QualType Ty = V->getType(); 364 if (!Ty->isBlockPointerType()) 365 return false; 366 367 if (!CheckablePrintfAttr(Format, TheCall)) 368 return false; 369 370 bool HasVAListArg = Format->getFirstArg() == 0; 371 CheckPrintfArguments(TheCall, HasVAListArg, Format->getFormatIdx() - 1, 372 HasVAListArg ? 0 : Format->getFirstArg() - 1); 373 374 return false; 375} 376 377/// SemaBuiltinAtomicOverloaded - We have a call to a function like 378/// __sync_fetch_and_add, which is an overloaded function based on the pointer 379/// type of its first argument. The main ActOnCallExpr routines have already 380/// promoted the types of arguments because all of these calls are prototyped as 381/// void(...). 382/// 383/// This function goes through and does final semantic checking for these 384/// builtins, 385bool Sema::SemaBuiltinAtomicOverloaded(CallExpr *TheCall) { 386 DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts()); 387 FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl()); 388 389 // Ensure that we have at least one argument to do type inference from. 390 if (TheCall->getNumArgs() < 1) 391 return Diag(TheCall->getLocEnd(), 392 diag::err_typecheck_call_too_few_args_at_least) 393 << 0 << 1 << TheCall->getNumArgs() 394 << TheCall->getCallee()->getSourceRange(); 395 396 // Inspect the first argument of the atomic builtin. This should always be 397 // a pointer type, whose element is an integral scalar or pointer type. 398 // Because it is a pointer type, we don't have to worry about any implicit 399 // casts here. 400 Expr *FirstArg = TheCall->getArg(0); 401 if (!FirstArg->getType()->isPointerType()) 402 return Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer) 403 << FirstArg->getType() << FirstArg->getSourceRange(); 404 405 QualType ValType = FirstArg->getType()->getAs<PointerType>()->getPointeeType(); 406 if (!ValType->isIntegerType() && !ValType->isPointerType() && 407 !ValType->isBlockPointerType()) 408 return Diag(DRE->getLocStart(), 409 diag::err_atomic_builtin_must_be_pointer_intptr) 410 << FirstArg->getType() << FirstArg->getSourceRange(); 411 412 // We need to figure out which concrete builtin this maps onto. For example, 413 // __sync_fetch_and_add with a 2 byte object turns into 414 // __sync_fetch_and_add_2. 415#define BUILTIN_ROW(x) \ 416 { Builtin::BI##x##_1, Builtin::BI##x##_2, Builtin::BI##x##_4, \ 417 Builtin::BI##x##_8, Builtin::BI##x##_16 } 418 419 static const unsigned BuiltinIndices[][5] = { 420 BUILTIN_ROW(__sync_fetch_and_add), 421 BUILTIN_ROW(__sync_fetch_and_sub), 422 BUILTIN_ROW(__sync_fetch_and_or), 423 BUILTIN_ROW(__sync_fetch_and_and), 424 BUILTIN_ROW(__sync_fetch_and_xor), 425 426 BUILTIN_ROW(__sync_add_and_fetch), 427 BUILTIN_ROW(__sync_sub_and_fetch), 428 BUILTIN_ROW(__sync_and_and_fetch), 429 BUILTIN_ROW(__sync_or_and_fetch), 430 BUILTIN_ROW(__sync_xor_and_fetch), 431 432 BUILTIN_ROW(__sync_val_compare_and_swap), 433 BUILTIN_ROW(__sync_bool_compare_and_swap), 434 BUILTIN_ROW(__sync_lock_test_and_set), 435 BUILTIN_ROW(__sync_lock_release) 436 }; 437#undef BUILTIN_ROW 438 439 // Determine the index of the size. 440 unsigned SizeIndex; 441 switch (Context.getTypeSizeInChars(ValType).getQuantity()) { 442 case 1: SizeIndex = 0; break; 443 case 2: SizeIndex = 1; break; 444 case 4: SizeIndex = 2; break; 445 case 8: SizeIndex = 3; break; 446 case 16: SizeIndex = 4; break; 447 default: 448 return Diag(DRE->getLocStart(), diag::err_atomic_builtin_pointer_size) 449 << FirstArg->getType() << FirstArg->getSourceRange(); 450 } 451 452 // Each of these builtins has one pointer argument, followed by some number of 453 // values (0, 1 or 2) followed by a potentially empty varags list of stuff 454 // that we ignore. Find out which row of BuiltinIndices to read from as well 455 // as the number of fixed args. 456 unsigned BuiltinID = FDecl->getBuiltinID(); 457 unsigned BuiltinIndex, NumFixed = 1; 458 switch (BuiltinID) { 459 default: assert(0 && "Unknown overloaded atomic builtin!"); 460 case Builtin::BI__sync_fetch_and_add: BuiltinIndex = 0; break; 461 case Builtin::BI__sync_fetch_and_sub: BuiltinIndex = 1; break; 462 case Builtin::BI__sync_fetch_and_or: BuiltinIndex = 2; break; 463 case Builtin::BI__sync_fetch_and_and: BuiltinIndex = 3; break; 464 case Builtin::BI__sync_fetch_and_xor: BuiltinIndex = 4; break; 465 466 case Builtin::BI__sync_add_and_fetch: BuiltinIndex = 5; break; 467 case Builtin::BI__sync_sub_and_fetch: BuiltinIndex = 6; break; 468 case Builtin::BI__sync_and_and_fetch: BuiltinIndex = 7; break; 469 case Builtin::BI__sync_or_and_fetch: BuiltinIndex = 8; break; 470 case Builtin::BI__sync_xor_and_fetch: BuiltinIndex = 9; break; 471 472 case Builtin::BI__sync_val_compare_and_swap: 473 BuiltinIndex = 10; 474 NumFixed = 2; 475 break; 476 case Builtin::BI__sync_bool_compare_and_swap: 477 BuiltinIndex = 11; 478 NumFixed = 2; 479 break; 480 case Builtin::BI__sync_lock_test_and_set: BuiltinIndex = 12; break; 481 case Builtin::BI__sync_lock_release: 482 BuiltinIndex = 13; 483 NumFixed = 0; 484 break; 485 } 486 487 // Now that we know how many fixed arguments we expect, first check that we 488 // have at least that many. 489 if (TheCall->getNumArgs() < 1+NumFixed) 490 return Diag(TheCall->getLocEnd(), 491 diag::err_typecheck_call_too_few_args_at_least) 492 << 0 << 1+NumFixed << TheCall->getNumArgs() 493 << TheCall->getCallee()->getSourceRange(); 494 495 496 // Get the decl for the concrete builtin from this, we can tell what the 497 // concrete integer type we should convert to is. 498 unsigned NewBuiltinID = BuiltinIndices[BuiltinIndex][SizeIndex]; 499 const char *NewBuiltinName = Context.BuiltinInfo.GetName(NewBuiltinID); 500 IdentifierInfo *NewBuiltinII = PP.getIdentifierInfo(NewBuiltinName); 501 FunctionDecl *NewBuiltinDecl = 502 cast<FunctionDecl>(LazilyCreateBuiltin(NewBuiltinII, NewBuiltinID, 503 TUScope, false, DRE->getLocStart())); 504 const FunctionProtoType *BuiltinFT = 505 NewBuiltinDecl->getType()->getAs<FunctionProtoType>(); 506 ValType = BuiltinFT->getArgType(0)->getAs<PointerType>()->getPointeeType(); 507 508 // If the first type needs to be converted (e.g. void** -> int*), do it now. 509 if (BuiltinFT->getArgType(0) != FirstArg->getType()) { 510 ImpCastExprToType(FirstArg, BuiltinFT->getArgType(0), CastExpr::CK_BitCast); 511 TheCall->setArg(0, FirstArg); 512 } 513 514 // Next, walk the valid ones promoting to the right type. 515 for (unsigned i = 0; i != NumFixed; ++i) { 516 Expr *Arg = TheCall->getArg(i+1); 517 518 // If the argument is an implicit cast, then there was a promotion due to 519 // "...", just remove it now. 520 if (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Arg)) { 521 Arg = ICE->getSubExpr(); 522 ICE->setSubExpr(0); 523 ICE->Destroy(Context); 524 TheCall->setArg(i+1, Arg); 525 } 526 527 // GCC does an implicit conversion to the pointer or integer ValType. This 528 // can fail in some cases (1i -> int**), check for this error case now. 529 CastExpr::CastKind Kind = CastExpr::CK_Unknown; 530 CXXBaseSpecifierArray BasePath; 531 if (CheckCastTypes(Arg->getSourceRange(), ValType, Arg, Kind, BasePath)) 532 return true; 533 534 // Okay, we have something that *can* be converted to the right type. Check 535 // to see if there is a potentially weird extension going on here. This can 536 // happen when you do an atomic operation on something like an char* and 537 // pass in 42. The 42 gets converted to char. This is even more strange 538 // for things like 45.123 -> char, etc. 539 // FIXME: Do this check. 540 ImpCastExprToType(Arg, ValType, Kind); 541 TheCall->setArg(i+1, Arg); 542 } 543 544 // Switch the DeclRefExpr to refer to the new decl. 545 DRE->setDecl(NewBuiltinDecl); 546 DRE->setType(NewBuiltinDecl->getType()); 547 548 // Set the callee in the CallExpr. 549 // FIXME: This leaks the original parens and implicit casts. 550 Expr *PromotedCall = DRE; 551 UsualUnaryConversions(PromotedCall); 552 TheCall->setCallee(PromotedCall); 553 554 555 // Change the result type of the call to match the result type of the decl. 556 TheCall->setType(NewBuiltinDecl->getResultType()); 557 return false; 558} 559 560 561/// CheckObjCString - Checks that the argument to the builtin 562/// CFString constructor is correct 563/// FIXME: GCC currently emits the following warning: 564/// "warning: input conversion stopped due to an input byte that does not 565/// belong to the input codeset UTF-8" 566/// Note: It might also make sense to do the UTF-16 conversion here (would 567/// simplify the backend). 568bool Sema::CheckObjCString(Expr *Arg) { 569 Arg = Arg->IgnoreParenCasts(); 570 StringLiteral *Literal = dyn_cast<StringLiteral>(Arg); 571 572 if (!Literal || Literal->isWide()) { 573 Diag(Arg->getLocStart(), diag::err_cfstring_literal_not_string_constant) 574 << Arg->getSourceRange(); 575 return true; 576 } 577 578 const char *Data = Literal->getStrData(); 579 unsigned Length = Literal->getByteLength(); 580 581 for (unsigned i = 0; i < Length; ++i) { 582 if (!Data[i]) { 583 Diag(getLocationOfStringLiteralByte(Literal, i), 584 diag::warn_cfstring_literal_contains_nul_character) 585 << Arg->getSourceRange(); 586 break; 587 } 588 } 589 590 return false; 591} 592 593/// SemaBuiltinVAStart - Check the arguments to __builtin_va_start for validity. 594/// Emit an error and return true on failure, return false on success. 595bool Sema::SemaBuiltinVAStart(CallExpr *TheCall) { 596 Expr *Fn = TheCall->getCallee(); 597 if (TheCall->getNumArgs() > 2) { 598 Diag(TheCall->getArg(2)->getLocStart(), 599 diag::err_typecheck_call_too_many_args) 600 << 0 /*function call*/ << 2 << TheCall->getNumArgs() 601 << Fn->getSourceRange() 602 << SourceRange(TheCall->getArg(2)->getLocStart(), 603 (*(TheCall->arg_end()-1))->getLocEnd()); 604 return true; 605 } 606 607 if (TheCall->getNumArgs() < 2) { 608 return Diag(TheCall->getLocEnd(), 609 diag::err_typecheck_call_too_few_args_at_least) 610 << 0 /*function call*/ << 2 << TheCall->getNumArgs(); 611 } 612 613 // Determine whether the current function is variadic or not. 614 BlockScopeInfo *CurBlock = getCurBlock(); 615 bool isVariadic; 616 if (CurBlock) 617 isVariadic = CurBlock->TheDecl->isVariadic(); 618 else if (FunctionDecl *FD = getCurFunctionDecl()) 619 isVariadic = FD->isVariadic(); 620 else 621 isVariadic = getCurMethodDecl()->isVariadic(); 622 623 if (!isVariadic) { 624 Diag(Fn->getLocStart(), diag::err_va_start_used_in_non_variadic_function); 625 return true; 626 } 627 628 // Verify that the second argument to the builtin is the last argument of the 629 // current function or method. 630 bool SecondArgIsLastNamedArgument = false; 631 const Expr *Arg = TheCall->getArg(1)->IgnoreParenCasts(); 632 633 if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Arg)) { 634 if (const ParmVarDecl *PV = dyn_cast<ParmVarDecl>(DR->getDecl())) { 635 // FIXME: This isn't correct for methods (results in bogus warning). 636 // Get the last formal in the current function. 637 const ParmVarDecl *LastArg; 638 if (CurBlock) 639 LastArg = *(CurBlock->TheDecl->param_end()-1); 640 else if (FunctionDecl *FD = getCurFunctionDecl()) 641 LastArg = *(FD->param_end()-1); 642 else 643 LastArg = *(getCurMethodDecl()->param_end()-1); 644 SecondArgIsLastNamedArgument = PV == LastArg; 645 } 646 } 647 648 if (!SecondArgIsLastNamedArgument) 649 Diag(TheCall->getArg(1)->getLocStart(), 650 diag::warn_second_parameter_of_va_start_not_last_named_argument); 651 return false; 652} 653 654/// SemaBuiltinUnorderedCompare - Handle functions like __builtin_isgreater and 655/// friends. This is declared to take (...), so we have to check everything. 656bool Sema::SemaBuiltinUnorderedCompare(CallExpr *TheCall) { 657 if (TheCall->getNumArgs() < 2) 658 return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args) 659 << 0 << 2 << TheCall->getNumArgs()/*function call*/; 660 if (TheCall->getNumArgs() > 2) 661 return Diag(TheCall->getArg(2)->getLocStart(), 662 diag::err_typecheck_call_too_many_args) 663 << 0 /*function call*/ << 2 << TheCall->getNumArgs() 664 << SourceRange(TheCall->getArg(2)->getLocStart(), 665 (*(TheCall->arg_end()-1))->getLocEnd()); 666 667 Expr *OrigArg0 = TheCall->getArg(0); 668 Expr *OrigArg1 = TheCall->getArg(1); 669 670 // Do standard promotions between the two arguments, returning their common 671 // type. 672 QualType Res = UsualArithmeticConversions(OrigArg0, OrigArg1, false); 673 674 // Make sure any conversions are pushed back into the call; this is 675 // type safe since unordered compare builtins are declared as "_Bool 676 // foo(...)". 677 TheCall->setArg(0, OrigArg0); 678 TheCall->setArg(1, OrigArg1); 679 680 if (OrigArg0->isTypeDependent() || OrigArg1->isTypeDependent()) 681 return false; 682 683 // If the common type isn't a real floating type, then the arguments were 684 // invalid for this operation. 685 if (!Res->isRealFloatingType()) 686 return Diag(OrigArg0->getLocStart(), 687 diag::err_typecheck_call_invalid_ordered_compare) 688 << OrigArg0->getType() << OrigArg1->getType() 689 << SourceRange(OrigArg0->getLocStart(), OrigArg1->getLocEnd()); 690 691 return false; 692} 693 694/// SemaBuiltinSemaBuiltinFPClassification - Handle functions like 695/// __builtin_isnan and friends. This is declared to take (...), so we have 696/// to check everything. We expect the last argument to be a floating point 697/// value. 698bool Sema::SemaBuiltinFPClassification(CallExpr *TheCall, unsigned NumArgs) { 699 if (TheCall->getNumArgs() < NumArgs) 700 return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args) 701 << 0 << NumArgs << TheCall->getNumArgs()/*function call*/; 702 if (TheCall->getNumArgs() > NumArgs) 703 return Diag(TheCall->getArg(NumArgs)->getLocStart(), 704 diag::err_typecheck_call_too_many_args) 705 << 0 /*function call*/ << NumArgs << TheCall->getNumArgs() 706 << SourceRange(TheCall->getArg(NumArgs)->getLocStart(), 707 (*(TheCall->arg_end()-1))->getLocEnd()); 708 709 Expr *OrigArg = TheCall->getArg(NumArgs-1); 710 711 if (OrigArg->isTypeDependent()) 712 return false; 713 714 // This operation requires a non-_Complex floating-point number. 715 if (!OrigArg->getType()->isRealFloatingType()) 716 return Diag(OrigArg->getLocStart(), 717 diag::err_typecheck_call_invalid_unary_fp) 718 << OrigArg->getType() << OrigArg->getSourceRange(); 719 720 // If this is an implicit conversion from float -> double, remove it. 721 if (ImplicitCastExpr *Cast = dyn_cast<ImplicitCastExpr>(OrigArg)) { 722 Expr *CastArg = Cast->getSubExpr(); 723 if (CastArg->getType()->isSpecificBuiltinType(BuiltinType::Float)) { 724 assert(Cast->getType()->isSpecificBuiltinType(BuiltinType::Double) && 725 "promotion from float to double is the only expected cast here"); 726 Cast->setSubExpr(0); 727 Cast->Destroy(Context); 728 TheCall->setArg(NumArgs-1, CastArg); 729 OrigArg = CastArg; 730 } 731 } 732 733 return false; 734} 735 736/// SemaBuiltinShuffleVector - Handle __builtin_shufflevector. 737// This is declared to take (...), so we have to check everything. 738Action::OwningExprResult Sema::SemaBuiltinShuffleVector(CallExpr *TheCall) { 739 if (TheCall->getNumArgs() < 2) 740 return ExprError(Diag(TheCall->getLocEnd(), 741 diag::err_typecheck_call_too_few_args_at_least) 742 << 0 /*function call*/ << 2 << TheCall->getNumArgs() 743 << TheCall->getSourceRange()); 744 745 // Determine which of the following types of shufflevector we're checking: 746 // 1) unary, vector mask: (lhs, mask) 747 // 2) binary, vector mask: (lhs, rhs, mask) 748 // 3) binary, scalar mask: (lhs, rhs, index, ..., index) 749 QualType resType = TheCall->getArg(0)->getType(); 750 unsigned numElements = 0; 751 752 if (!TheCall->getArg(0)->isTypeDependent() && 753 !TheCall->getArg(1)->isTypeDependent()) { 754 QualType LHSType = TheCall->getArg(0)->getType(); 755 QualType RHSType = TheCall->getArg(1)->getType(); 756 757 if (!LHSType->isVectorType() || !RHSType->isVectorType()) { 758 Diag(TheCall->getLocStart(), diag::err_shufflevector_non_vector) 759 << SourceRange(TheCall->getArg(0)->getLocStart(), 760 TheCall->getArg(1)->getLocEnd()); 761 return ExprError(); 762 } 763 764 numElements = LHSType->getAs<VectorType>()->getNumElements(); 765 unsigned numResElements = TheCall->getNumArgs() - 2; 766 767 // Check to see if we have a call with 2 vector arguments, the unary shuffle 768 // with mask. If so, verify that RHS is an integer vector type with the 769 // same number of elts as lhs. 770 if (TheCall->getNumArgs() == 2) { 771 if (!RHSType->isIntegerType() || 772 RHSType->getAs<VectorType>()->getNumElements() != numElements) 773 Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector) 774 << SourceRange(TheCall->getArg(1)->getLocStart(), 775 TheCall->getArg(1)->getLocEnd()); 776 numResElements = numElements; 777 } 778 else if (!Context.hasSameUnqualifiedType(LHSType, RHSType)) { 779 Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector) 780 << SourceRange(TheCall->getArg(0)->getLocStart(), 781 TheCall->getArg(1)->getLocEnd()); 782 return ExprError(); 783 } else if (numElements != numResElements) { 784 QualType eltType = LHSType->getAs<VectorType>()->getElementType(); 785 resType = Context.getVectorType(eltType, numResElements, false, false); 786 } 787 } 788 789 for (unsigned i = 2; i < TheCall->getNumArgs(); i++) { 790 if (TheCall->getArg(i)->isTypeDependent() || 791 TheCall->getArg(i)->isValueDependent()) 792 continue; 793 794 llvm::APSInt Result(32); 795 if (!TheCall->getArg(i)->isIntegerConstantExpr(Result, Context)) 796 return ExprError(Diag(TheCall->getLocStart(), 797 diag::err_shufflevector_nonconstant_argument) 798 << TheCall->getArg(i)->getSourceRange()); 799 800 if (Result.getActiveBits() > 64 || Result.getZExtValue() >= numElements*2) 801 return ExprError(Diag(TheCall->getLocStart(), 802 diag::err_shufflevector_argument_too_large) 803 << TheCall->getArg(i)->getSourceRange()); 804 } 805 806 llvm::SmallVector<Expr*, 32> exprs; 807 808 for (unsigned i = 0, e = TheCall->getNumArgs(); i != e; i++) { 809 exprs.push_back(TheCall->getArg(i)); 810 TheCall->setArg(i, 0); 811 } 812 813 return Owned(new (Context) ShuffleVectorExpr(Context, exprs.begin(), 814 exprs.size(), resType, 815 TheCall->getCallee()->getLocStart(), 816 TheCall->getRParenLoc())); 817} 818 819/// SemaBuiltinPrefetch - Handle __builtin_prefetch. 820// This is declared to take (const void*, ...) and can take two 821// optional constant int args. 822bool Sema::SemaBuiltinPrefetch(CallExpr *TheCall) { 823 unsigned NumArgs = TheCall->getNumArgs(); 824 825 if (NumArgs > 3) 826 return Diag(TheCall->getLocEnd(), 827 diag::err_typecheck_call_too_many_args_at_most) 828 << 0 /*function call*/ << 3 << NumArgs 829 << TheCall->getSourceRange(); 830 831 // Argument 0 is checked for us and the remaining arguments must be 832 // constant integers. 833 for (unsigned i = 1; i != NumArgs; ++i) { 834 Expr *Arg = TheCall->getArg(i); 835 836 llvm::APSInt Result; 837 if (SemaBuiltinConstantArg(TheCall, i, Result)) 838 return true; 839 840 // FIXME: gcc issues a warning and rewrites these to 0. These 841 // seems especially odd for the third argument since the default 842 // is 3. 843 if (i == 1) { 844 if (Result.getLimitedValue() > 1) 845 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 846 << "0" << "1" << Arg->getSourceRange(); 847 } else { 848 if (Result.getLimitedValue() > 3) 849 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 850 << "0" << "3" << Arg->getSourceRange(); 851 } 852 } 853 854 return false; 855} 856 857/// SemaBuiltinConstantArg - Handle a check if argument ArgNum of CallExpr 858/// TheCall is a constant expression. 859bool Sema::SemaBuiltinConstantArg(CallExpr *TheCall, int ArgNum, 860 llvm::APSInt &Result) { 861 Expr *Arg = TheCall->getArg(ArgNum); 862 DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts()); 863 FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl()); 864 865 if (Arg->isTypeDependent() || Arg->isValueDependent()) return false; 866 867 if (!Arg->isIntegerConstantExpr(Result, Context)) 868 return Diag(TheCall->getLocStart(), diag::err_constant_integer_arg_type) 869 << FDecl->getDeclName() << Arg->getSourceRange(); 870 871 return false; 872} 873 874/// SemaBuiltinObjectSize - Handle __builtin_object_size(void *ptr, 875/// int type). This simply type checks that type is one of the defined 876/// constants (0-3). 877// For compatability check 0-3, llvm only handles 0 and 2. 878bool Sema::SemaBuiltinObjectSize(CallExpr *TheCall) { 879 llvm::APSInt Result; 880 881 // Check constant-ness first. 882 if (SemaBuiltinConstantArg(TheCall, 1, Result)) 883 return true; 884 885 Expr *Arg = TheCall->getArg(1); 886 if (Result.getSExtValue() < 0 || Result.getSExtValue() > 3) { 887 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 888 << "0" << "3" << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); 889 } 890 891 return false; 892} 893 894/// SemaBuiltinLongjmp - Handle __builtin_longjmp(void *env[5], int val). 895/// This checks that val is a constant 1. 896bool Sema::SemaBuiltinLongjmp(CallExpr *TheCall) { 897 Expr *Arg = TheCall->getArg(1); 898 llvm::APSInt Result; 899 900 // TODO: This is less than ideal. Overload this to take a value. 901 if (SemaBuiltinConstantArg(TheCall, 1, Result)) 902 return true; 903 904 if (Result != 1) 905 return Diag(TheCall->getLocStart(), diag::err_builtin_longjmp_invalid_val) 906 << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); 907 908 return false; 909} 910 911// Handle i > 1 ? "x" : "y", recursivelly 912bool Sema::SemaCheckStringLiteral(const Expr *E, const CallExpr *TheCall, 913 bool HasVAListArg, 914 unsigned format_idx, unsigned firstDataArg) { 915 if (E->isTypeDependent() || E->isValueDependent()) 916 return false; 917 918 switch (E->getStmtClass()) { 919 case Stmt::ConditionalOperatorClass: { 920 const ConditionalOperator *C = cast<ConditionalOperator>(E); 921 return SemaCheckStringLiteral(C->getTrueExpr(), TheCall, 922 HasVAListArg, format_idx, firstDataArg) 923 && SemaCheckStringLiteral(C->getRHS(), TheCall, 924 HasVAListArg, format_idx, firstDataArg); 925 } 926 927 case Stmt::ImplicitCastExprClass: { 928 const ImplicitCastExpr *Expr = cast<ImplicitCastExpr>(E); 929 return SemaCheckStringLiteral(Expr->getSubExpr(), TheCall, HasVAListArg, 930 format_idx, firstDataArg); 931 } 932 933 case Stmt::ParenExprClass: { 934 const ParenExpr *Expr = cast<ParenExpr>(E); 935 return SemaCheckStringLiteral(Expr->getSubExpr(), TheCall, HasVAListArg, 936 format_idx, firstDataArg); 937 } 938 939 case Stmt::DeclRefExprClass: { 940 const DeclRefExpr *DR = cast<DeclRefExpr>(E); 941 942 // As an exception, do not flag errors for variables binding to 943 // const string literals. 944 if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) { 945 bool isConstant = false; 946 QualType T = DR->getType(); 947 948 if (const ArrayType *AT = Context.getAsArrayType(T)) { 949 isConstant = AT->getElementType().isConstant(Context); 950 } else if (const PointerType *PT = T->getAs<PointerType>()) { 951 isConstant = T.isConstant(Context) && 952 PT->getPointeeType().isConstant(Context); 953 } 954 955 if (isConstant) { 956 if (const Expr *Init = VD->getAnyInitializer()) 957 return SemaCheckStringLiteral(Init, TheCall, 958 HasVAListArg, format_idx, firstDataArg); 959 } 960 961 // For vprintf* functions (i.e., HasVAListArg==true), we add a 962 // special check to see if the format string is a function parameter 963 // of the function calling the printf function. If the function 964 // has an attribute indicating it is a printf-like function, then we 965 // should suppress warnings concerning non-literals being used in a call 966 // to a vprintf function. For example: 967 // 968 // void 969 // logmessage(char const *fmt __attribute__ (format (printf, 1, 2)), ...){ 970 // va_list ap; 971 // va_start(ap, fmt); 972 // vprintf(fmt, ap); // Do NOT emit a warning about "fmt". 973 // ... 974 // 975 // 976 // FIXME: We don't have full attribute support yet, so just check to see 977 // if the argument is a DeclRefExpr that references a parameter. We'll 978 // add proper support for checking the attribute later. 979 if (HasVAListArg) 980 if (isa<ParmVarDecl>(VD)) 981 return true; 982 } 983 984 return false; 985 } 986 987 case Stmt::CallExprClass: { 988 const CallExpr *CE = cast<CallExpr>(E); 989 if (const ImplicitCastExpr *ICE 990 = dyn_cast<ImplicitCastExpr>(CE->getCallee())) { 991 if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(ICE->getSubExpr())) { 992 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(DRE->getDecl())) { 993 if (const FormatArgAttr *FA = FD->getAttr<FormatArgAttr>()) { 994 unsigned ArgIndex = FA->getFormatIdx(); 995 const Expr *Arg = CE->getArg(ArgIndex - 1); 996 997 return SemaCheckStringLiteral(Arg, TheCall, HasVAListArg, 998 format_idx, firstDataArg); 999 } 1000 } 1001 } 1002 } 1003 1004 return false; 1005 } 1006 case Stmt::ObjCStringLiteralClass: 1007 case Stmt::StringLiteralClass: { 1008 const StringLiteral *StrE = NULL; 1009 1010 if (const ObjCStringLiteral *ObjCFExpr = dyn_cast<ObjCStringLiteral>(E)) 1011 StrE = ObjCFExpr->getString(); 1012 else 1013 StrE = cast<StringLiteral>(E); 1014 1015 if (StrE) { 1016 CheckPrintfString(StrE, E, TheCall, HasVAListArg, format_idx, 1017 firstDataArg); 1018 return true; 1019 } 1020 1021 return false; 1022 } 1023 1024 default: 1025 return false; 1026 } 1027} 1028 1029void 1030Sema::CheckNonNullArguments(const NonNullAttr *NonNull, 1031 const CallExpr *TheCall) { 1032 for (NonNullAttr::iterator i = NonNull->begin(), e = NonNull->end(); 1033 i != e; ++i) { 1034 const Expr *ArgExpr = TheCall->getArg(*i); 1035 if (ArgExpr->isNullPointerConstant(Context, 1036 Expr::NPC_ValueDependentIsNotNull)) 1037 Diag(TheCall->getCallee()->getLocStart(), diag::warn_null_arg) 1038 << ArgExpr->getSourceRange(); 1039 } 1040} 1041 1042/// CheckPrintfArguments - Check calls to printf (and similar functions) for 1043/// correct use of format strings. 1044/// 1045/// HasVAListArg - A predicate indicating whether the printf-like 1046/// function is passed an explicit va_arg argument (e.g., vprintf) 1047/// 1048/// format_idx - The index into Args for the format string. 1049/// 1050/// Improper format strings to functions in the printf family can be 1051/// the source of bizarre bugs and very serious security holes. A 1052/// good source of information is available in the following paper 1053/// (which includes additional references): 1054/// 1055/// FormatGuard: Automatic Protection From printf Format String 1056/// Vulnerabilities, Proceedings of the 10th USENIX Security Symposium, 2001. 1057/// 1058/// TODO: 1059/// Functionality implemented: 1060/// 1061/// We can statically check the following properties for string 1062/// literal format strings for non v.*printf functions (where the 1063/// arguments are passed directly): 1064// 1065/// (1) Are the number of format conversions equal to the number of 1066/// data arguments? 1067/// 1068/// (2) Does each format conversion correctly match the type of the 1069/// corresponding data argument? 1070/// 1071/// Moreover, for all printf functions we can: 1072/// 1073/// (3) Check for a missing format string (when not caught by type checking). 1074/// 1075/// (4) Check for no-operation flags; e.g. using "#" with format 1076/// conversion 'c' (TODO) 1077/// 1078/// (5) Check the use of '%n', a major source of security holes. 1079/// 1080/// (6) Check for malformed format conversions that don't specify anything. 1081/// 1082/// (7) Check for empty format strings. e.g: printf(""); 1083/// 1084/// (8) Check that the format string is a wide literal. 1085/// 1086/// All of these checks can be done by parsing the format string. 1087/// 1088void 1089Sema::CheckPrintfArguments(const CallExpr *TheCall, bool HasVAListArg, 1090 unsigned format_idx, unsigned firstDataArg) { 1091 const Expr *Fn = TheCall->getCallee(); 1092 1093 // The way the format attribute works in GCC, the implicit this argument 1094 // of member functions is counted. However, it doesn't appear in our own 1095 // lists, so decrement format_idx in that case. 1096 if (isa<CXXMemberCallExpr>(TheCall)) { 1097 // Catch a format attribute mistakenly referring to the object argument. 1098 if (format_idx == 0) 1099 return; 1100 --format_idx; 1101 if(firstDataArg != 0) 1102 --firstDataArg; 1103 } 1104 1105 // CHECK: printf-like function is called with no format string. 1106 if (format_idx >= TheCall->getNumArgs()) { 1107 Diag(TheCall->getRParenLoc(), diag::warn_printf_missing_format_string) 1108 << Fn->getSourceRange(); 1109 return; 1110 } 1111 1112 const Expr *OrigFormatExpr = TheCall->getArg(format_idx)->IgnoreParenCasts(); 1113 1114 // CHECK: format string is not a string literal. 1115 // 1116 // Dynamically generated format strings are difficult to 1117 // automatically vet at compile time. Requiring that format strings 1118 // are string literals: (1) permits the checking of format strings by 1119 // the compiler and thereby (2) can practically remove the source of 1120 // many format string exploits. 1121 1122 // Format string can be either ObjC string (e.g. @"%d") or 1123 // C string (e.g. "%d") 1124 // ObjC string uses the same format specifiers as C string, so we can use 1125 // the same format string checking logic for both ObjC and C strings. 1126 if (SemaCheckStringLiteral(OrigFormatExpr, TheCall, HasVAListArg, format_idx, 1127 firstDataArg)) 1128 return; // Literal format string found, check done! 1129 1130 // If there are no arguments specified, warn with -Wformat-security, otherwise 1131 // warn only with -Wformat-nonliteral. 1132 if (TheCall->getNumArgs() == format_idx+1) 1133 Diag(TheCall->getArg(format_idx)->getLocStart(), 1134 diag::warn_printf_nonliteral_noargs) 1135 << OrigFormatExpr->getSourceRange(); 1136 else 1137 Diag(TheCall->getArg(format_idx)->getLocStart(), 1138 diag::warn_printf_nonliteral) 1139 << OrigFormatExpr->getSourceRange(); 1140} 1141 1142namespace { 1143class CheckPrintfHandler : public analyze_printf::FormatStringHandler { 1144 Sema &S; 1145 const StringLiteral *FExpr; 1146 const Expr *OrigFormatExpr; 1147 const unsigned FirstDataArg; 1148 const unsigned NumDataArgs; 1149 const bool IsObjCLiteral; 1150 const char *Beg; // Start of format string. 1151 const bool HasVAListArg; 1152 const CallExpr *TheCall; 1153 unsigned FormatIdx; 1154 llvm::BitVector CoveredArgs; 1155 bool usesPositionalArgs; 1156 bool atFirstArg; 1157public: 1158 CheckPrintfHandler(Sema &s, const StringLiteral *fexpr, 1159 const Expr *origFormatExpr, unsigned firstDataArg, 1160 unsigned numDataArgs, bool isObjCLiteral, 1161 const char *beg, bool hasVAListArg, 1162 const CallExpr *theCall, unsigned formatIdx) 1163 : S(s), FExpr(fexpr), OrigFormatExpr(origFormatExpr), 1164 FirstDataArg(firstDataArg), 1165 NumDataArgs(numDataArgs), 1166 IsObjCLiteral(isObjCLiteral), Beg(beg), 1167 HasVAListArg(hasVAListArg), 1168 TheCall(theCall), FormatIdx(formatIdx), 1169 usesPositionalArgs(false), atFirstArg(true) { 1170 CoveredArgs.resize(numDataArgs); 1171 CoveredArgs.reset(); 1172 } 1173 1174 void DoneProcessing(); 1175 1176 void HandleIncompleteFormatSpecifier(const char *startSpecifier, 1177 unsigned specifierLen); 1178 1179 bool 1180 HandleInvalidConversionSpecifier(const analyze_printf::FormatSpecifier &FS, 1181 const char *startSpecifier, 1182 unsigned specifierLen); 1183 1184 virtual void HandleInvalidPosition(const char *startSpecifier, 1185 unsigned specifierLen, 1186 analyze_printf::PositionContext p); 1187 1188 virtual void HandleZeroPosition(const char *startPos, unsigned posLen); 1189 1190 void HandleNullChar(const char *nullCharacter); 1191 1192 bool HandleFormatSpecifier(const analyze_printf::FormatSpecifier &FS, 1193 const char *startSpecifier, 1194 unsigned specifierLen); 1195private: 1196 SourceRange getFormatStringRange(); 1197 SourceRange getFormatSpecifierRange(const char *startSpecifier, 1198 unsigned specifierLen); 1199 SourceLocation getLocationOfByte(const char *x); 1200 1201 bool HandleAmount(const analyze_printf::OptionalAmount &Amt, unsigned k, 1202 const char *startSpecifier, unsigned specifierLen); 1203 void HandleInvalidAmount(const analyze_printf::FormatSpecifier &FS, 1204 const analyze_printf::OptionalAmount &Amt, 1205 unsigned type, 1206 const char *startSpecifier, unsigned specifierLen); 1207 void HandleFlag(const analyze_printf::FormatSpecifier &FS, 1208 const analyze_printf::OptionalFlag &flag, 1209 const char *startSpecifier, unsigned specifierLen); 1210 void HandleIgnoredFlag(const analyze_printf::FormatSpecifier &FS, 1211 const analyze_printf::OptionalFlag &ignoredFlag, 1212 const analyze_printf::OptionalFlag &flag, 1213 const char *startSpecifier, unsigned specifierLen); 1214 1215 const Expr *getDataArg(unsigned i) const; 1216}; 1217} 1218 1219SourceRange CheckPrintfHandler::getFormatStringRange() { 1220 return OrigFormatExpr->getSourceRange(); 1221} 1222 1223SourceRange CheckPrintfHandler:: 1224getFormatSpecifierRange(const char *startSpecifier, unsigned specifierLen) { 1225 return SourceRange(getLocationOfByte(startSpecifier), 1226 getLocationOfByte(startSpecifier+specifierLen-1)); 1227} 1228 1229SourceLocation CheckPrintfHandler::getLocationOfByte(const char *x) { 1230 return S.getLocationOfStringLiteralByte(FExpr, x - Beg); 1231} 1232 1233void CheckPrintfHandler:: 1234HandleIncompleteFormatSpecifier(const char *startSpecifier, 1235 unsigned specifierLen) { 1236 SourceLocation Loc = getLocationOfByte(startSpecifier); 1237 S.Diag(Loc, diag::warn_printf_incomplete_specifier) 1238 << getFormatSpecifierRange(startSpecifier, specifierLen); 1239} 1240 1241void 1242CheckPrintfHandler::HandleInvalidPosition(const char *startPos, unsigned posLen, 1243 analyze_printf::PositionContext p) { 1244 SourceLocation Loc = getLocationOfByte(startPos); 1245 S.Diag(Loc, diag::warn_printf_invalid_positional_specifier) 1246 << (unsigned) p << getFormatSpecifierRange(startPos, posLen); 1247} 1248 1249void CheckPrintfHandler::HandleZeroPosition(const char *startPos, 1250 unsigned posLen) { 1251 SourceLocation Loc = getLocationOfByte(startPos); 1252 S.Diag(Loc, diag::warn_printf_zero_positional_specifier) 1253 << getFormatSpecifierRange(startPos, posLen); 1254} 1255 1256bool CheckPrintfHandler:: 1257HandleInvalidConversionSpecifier(const analyze_printf::FormatSpecifier &FS, 1258 const char *startSpecifier, 1259 unsigned specifierLen) { 1260 1261 unsigned argIndex = FS.getArgIndex(); 1262 bool keepGoing = true; 1263 if (argIndex < NumDataArgs) { 1264 // Consider the argument coverered, even though the specifier doesn't 1265 // make sense. 1266 CoveredArgs.set(argIndex); 1267 } 1268 else { 1269 // If argIndex exceeds the number of data arguments we 1270 // don't issue a warning because that is just a cascade of warnings (and 1271 // they may have intended '%%' anyway). We don't want to continue processing 1272 // the format string after this point, however, as we will like just get 1273 // gibberish when trying to match arguments. 1274 keepGoing = false; 1275 } 1276 1277 const analyze_printf::ConversionSpecifier &CS = 1278 FS.getConversionSpecifier(); 1279 SourceLocation Loc = getLocationOfByte(CS.getStart()); 1280 S.Diag(Loc, diag::warn_printf_invalid_conversion) 1281 << llvm::StringRef(CS.getStart(), CS.getLength()) 1282 << getFormatSpecifierRange(startSpecifier, specifierLen); 1283 1284 return keepGoing; 1285} 1286 1287void CheckPrintfHandler::HandleNullChar(const char *nullCharacter) { 1288 // The presence of a null character is likely an error. 1289 S.Diag(getLocationOfByte(nullCharacter), 1290 diag::warn_printf_format_string_contains_null_char) 1291 << getFormatStringRange(); 1292} 1293 1294const Expr *CheckPrintfHandler::getDataArg(unsigned i) const { 1295 return TheCall->getArg(FirstDataArg + i); 1296} 1297 1298bool 1299CheckPrintfHandler::HandleAmount(const analyze_printf::OptionalAmount &Amt, 1300 unsigned k, const char *startSpecifier, 1301 unsigned specifierLen) { 1302 1303 if (Amt.hasDataArgument()) { 1304 if (!HasVAListArg) { 1305 unsigned argIndex = Amt.getArgIndex(); 1306 if (argIndex >= NumDataArgs) { 1307 S.Diag(getLocationOfByte(Amt.getStart()), 1308 diag::warn_printf_asterisk_missing_arg) 1309 << k << getFormatSpecifierRange(startSpecifier, specifierLen); 1310 // Don't do any more checking. We will just emit 1311 // spurious errors. 1312 return false; 1313 } 1314 1315 // Type check the data argument. It should be an 'int'. 1316 // Although not in conformance with C99, we also allow the argument to be 1317 // an 'unsigned int' as that is a reasonably safe case. GCC also 1318 // doesn't emit a warning for that case. 1319 CoveredArgs.set(argIndex); 1320 const Expr *Arg = getDataArg(argIndex); 1321 QualType T = Arg->getType(); 1322 1323 const analyze_printf::ArgTypeResult &ATR = Amt.getArgType(S.Context); 1324 assert(ATR.isValid()); 1325 1326 if (!ATR.matchesType(S.Context, T)) { 1327 S.Diag(getLocationOfByte(Amt.getStart()), 1328 diag::warn_printf_asterisk_wrong_type) 1329 << k 1330 << ATR.getRepresentativeType(S.Context) << T 1331 << getFormatSpecifierRange(startSpecifier, specifierLen) 1332 << Arg->getSourceRange(); 1333 // Don't do any more checking. We will just emit 1334 // spurious errors. 1335 return false; 1336 } 1337 } 1338 } 1339 return true; 1340} 1341 1342void CheckPrintfHandler::HandleInvalidAmount( 1343 const analyze_printf::FormatSpecifier &FS, 1344 const analyze_printf::OptionalAmount &Amt, 1345 unsigned type, 1346 const char *startSpecifier, 1347 unsigned specifierLen) { 1348 const analyze_printf::ConversionSpecifier &CS = FS.getConversionSpecifier(); 1349 switch (Amt.getHowSpecified()) { 1350 case analyze_printf::OptionalAmount::Constant: 1351 S.Diag(getLocationOfByte(Amt.getStart()), 1352 diag::warn_printf_nonsensical_optional_amount) 1353 << type 1354 << CS.toString() 1355 << getFormatSpecifierRange(startSpecifier, specifierLen) 1356 << FixItHint::CreateRemoval(getFormatSpecifierRange(Amt.getStart(), 1357 Amt.getConstantLength())); 1358 break; 1359 1360 default: 1361 S.Diag(getLocationOfByte(Amt.getStart()), 1362 diag::warn_printf_nonsensical_optional_amount) 1363 << type 1364 << CS.toString() 1365 << getFormatSpecifierRange(startSpecifier, specifierLen); 1366 break; 1367 } 1368} 1369 1370void CheckPrintfHandler::HandleFlag(const analyze_printf::FormatSpecifier &FS, 1371 const analyze_printf::OptionalFlag &flag, 1372 const char *startSpecifier, 1373 unsigned specifierLen) { 1374 // Warn about pointless flag with a fixit removal. 1375 const analyze_printf::ConversionSpecifier &CS = FS.getConversionSpecifier(); 1376 S.Diag(getLocationOfByte(flag.getPosition()), 1377 diag::warn_printf_nonsensical_flag) 1378 << flag.toString() << CS.toString() 1379 << getFormatSpecifierRange(startSpecifier, specifierLen) 1380 << FixItHint::CreateRemoval(getFormatSpecifierRange(flag.getPosition(), 1)); 1381} 1382 1383void CheckPrintfHandler::HandleIgnoredFlag( 1384 const analyze_printf::FormatSpecifier &FS, 1385 const analyze_printf::OptionalFlag &ignoredFlag, 1386 const analyze_printf::OptionalFlag &flag, 1387 const char *startSpecifier, 1388 unsigned specifierLen) { 1389 // Warn about ignored flag with a fixit removal. 1390 S.Diag(getLocationOfByte(ignoredFlag.getPosition()), 1391 diag::warn_printf_ignored_flag) 1392 << ignoredFlag.toString() << flag.toString() 1393 << getFormatSpecifierRange(startSpecifier, specifierLen) 1394 << FixItHint::CreateRemoval(getFormatSpecifierRange( 1395 ignoredFlag.getPosition(), 1)); 1396} 1397 1398bool 1399CheckPrintfHandler::HandleFormatSpecifier(const analyze_printf::FormatSpecifier 1400 &FS, 1401 const char *startSpecifier, 1402 unsigned specifierLen) { 1403 1404 using namespace analyze_printf; 1405 const ConversionSpecifier &CS = FS.getConversionSpecifier(); 1406 1407 if (atFirstArg) { 1408 atFirstArg = false; 1409 usesPositionalArgs = FS.usesPositionalArg(); 1410 } 1411 else if (usesPositionalArgs != FS.usesPositionalArg()) { 1412 // Cannot mix-and-match positional and non-positional arguments. 1413 S.Diag(getLocationOfByte(CS.getStart()), 1414 diag::warn_printf_mix_positional_nonpositional_args) 1415 << getFormatSpecifierRange(startSpecifier, specifierLen); 1416 return false; 1417 } 1418 1419 // First check if the field width, precision, and conversion specifier 1420 // have matching data arguments. 1421 if (!HandleAmount(FS.getFieldWidth(), /* field width */ 0, 1422 startSpecifier, specifierLen)) { 1423 return false; 1424 } 1425 1426 if (!HandleAmount(FS.getPrecision(), /* precision */ 1, 1427 startSpecifier, specifierLen)) { 1428 return false; 1429 } 1430 1431 if (!CS.consumesDataArgument()) { 1432 // FIXME: Technically specifying a precision or field width here 1433 // makes no sense. Worth issuing a warning at some point. 1434 return true; 1435 } 1436 1437 // Consume the argument. 1438 unsigned argIndex = FS.getArgIndex(); 1439 if (argIndex < NumDataArgs) { 1440 // The check to see if the argIndex is valid will come later. 1441 // We set the bit here because we may exit early from this 1442 // function if we encounter some other error. 1443 CoveredArgs.set(argIndex); 1444 } 1445 1446 // Check for using an Objective-C specific conversion specifier 1447 // in a non-ObjC literal. 1448 if (!IsObjCLiteral && CS.isObjCArg()) { 1449 return HandleInvalidConversionSpecifier(FS, startSpecifier, specifierLen); 1450 } 1451 1452 // Check for invalid use of field width 1453 if (!FS.hasValidFieldWidth()) { 1454 HandleInvalidAmount(FS, FS.getFieldWidth(), /* field width */ 1, 1455 startSpecifier, specifierLen); 1456 } 1457 1458 // Check for invalid use of precision 1459 if (!FS.hasValidPrecision()) { 1460 HandleInvalidAmount(FS, FS.getPrecision(), /* precision */ 1, 1461 startSpecifier, specifierLen); 1462 } 1463 1464 // Check each flag does not conflict with any other component. 1465 if (!FS.hasValidLeadingZeros()) 1466 HandleFlag(FS, FS.hasLeadingZeros(), startSpecifier, specifierLen); 1467 if (!FS.hasValidPlusPrefix()) 1468 HandleFlag(FS, FS.hasPlusPrefix(), startSpecifier, specifierLen); 1469 // FIXME: the following lines are disabled due to clang assertions on 1470 // highlights containing spaces. 1471 // if (!FS.hasValidSpacePrefix()) 1472 // HandleFlag(FS, FS.hasSpacePrefix(), startSpecifier, specifierLen); 1473 if (!FS.hasValidAlternativeForm()) 1474 HandleFlag(FS, FS.hasAlternativeForm(), startSpecifier, specifierLen); 1475 if (!FS.hasValidLeftJustified()) 1476 HandleFlag(FS, FS.isLeftJustified(), startSpecifier, specifierLen); 1477 1478 // Check that flags are not ignored by another flag 1479 // FIXME: the following lines are disabled due to clang assertions on 1480 // highlights containing spaces. 1481 //if (FS.hasSpacePrefix() && FS.hasPlusPrefix()) // ' ' ignored by '+' 1482 // HandleIgnoredFlag(FS, FS.hasSpacePrefix(), FS.hasPlusPrefix(), 1483 // startSpecifier, specifierLen); 1484 if (FS.hasLeadingZeros() && FS.isLeftJustified()) // '0' ignored by '-' 1485 HandleIgnoredFlag(FS, FS.hasLeadingZeros(), FS.isLeftJustified(), 1486 startSpecifier, specifierLen); 1487 1488 // Check the length modifier is valid with the given conversion specifier. 1489 const LengthModifier &LM = FS.getLengthModifier(); 1490 if (!FS.hasValidLengthModifier()) 1491 S.Diag(getLocationOfByte(LM.getStart()), 1492 diag::warn_printf_nonsensical_length) 1493 << LM.toString() << CS.toString() 1494 << getFormatSpecifierRange(startSpecifier, specifierLen) 1495 << FixItHint::CreateRemoval(getFormatSpecifierRange(LM.getStart(), 1496 LM.getLength())); 1497 1498 // Are we using '%n'? 1499 if (CS.getKind() == ConversionSpecifier::OutIntPtrArg) { 1500 // Issue a warning about this being a possible security issue. 1501 S.Diag(getLocationOfByte(CS.getStart()), diag::warn_printf_write_back) 1502 << getFormatSpecifierRange(startSpecifier, specifierLen); 1503 // Continue checking the other format specifiers. 1504 return true; 1505 } 1506 1507 // The remaining checks depend on the data arguments. 1508 if (HasVAListArg) 1509 return true; 1510 1511 if (argIndex >= NumDataArgs) { 1512 if (FS.usesPositionalArg()) { 1513 S.Diag(getLocationOfByte(CS.getStart()), 1514 diag::warn_printf_positional_arg_exceeds_data_args) 1515 << (argIndex+1) << NumDataArgs 1516 << getFormatSpecifierRange(startSpecifier, specifierLen); 1517 } 1518 else { 1519 S.Diag(getLocationOfByte(CS.getStart()), 1520 diag::warn_printf_insufficient_data_args) 1521 << getFormatSpecifierRange(startSpecifier, specifierLen); 1522 } 1523 1524 // Don't do any more checking. 1525 return false; 1526 } 1527 1528 // Now type check the data expression that matches the 1529 // format specifier. 1530 const Expr *Ex = getDataArg(argIndex); 1531 const analyze_printf::ArgTypeResult &ATR = FS.getArgType(S.Context); 1532 if (ATR.isValid() && !ATR.matchesType(S.Context, Ex->getType())) { 1533 // Check if we didn't match because of an implicit cast from a 'char' 1534 // or 'short' to an 'int'. This is done because printf is a varargs 1535 // function. 1536 if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Ex)) 1537 if (ICE->getType() == S.Context.IntTy) 1538 if (ATR.matchesType(S.Context, ICE->getSubExpr()->getType())) 1539 return true; 1540 1541 // We may be able to offer a FixItHint if it is a supported type. 1542 FormatSpecifier fixedFS = FS; 1543 bool success = fixedFS.fixType(Ex->getType()); 1544 1545 if (success) { 1546 // Get the fix string from the fixed format specifier 1547 llvm::SmallString<128> buf; 1548 llvm::raw_svector_ostream os(buf); 1549 fixedFS.toString(os); 1550 1551 S.Diag(getLocationOfByte(CS.getStart()), 1552 diag::warn_printf_conversion_argument_type_mismatch) 1553 << ATR.getRepresentativeType(S.Context) << Ex->getType() 1554 << getFormatSpecifierRange(startSpecifier, specifierLen) 1555 << Ex->getSourceRange() 1556 << FixItHint::CreateReplacement( 1557 getFormatSpecifierRange(startSpecifier, specifierLen), 1558 os.str()); 1559 } 1560 else { 1561 S.Diag(getLocationOfByte(CS.getStart()), 1562 diag::warn_printf_conversion_argument_type_mismatch) 1563 << ATR.getRepresentativeType(S.Context) << Ex->getType() 1564 << getFormatSpecifierRange(startSpecifier, specifierLen) 1565 << Ex->getSourceRange(); 1566 } 1567 } 1568 1569 return true; 1570} 1571 1572void CheckPrintfHandler::DoneProcessing() { 1573 // Does the number of data arguments exceed the number of 1574 // format conversions in the format string? 1575 if (!HasVAListArg) { 1576 // Find any arguments that weren't covered. 1577 CoveredArgs.flip(); 1578 signed notCoveredArg = CoveredArgs.find_first(); 1579 if (notCoveredArg >= 0) { 1580 assert((unsigned)notCoveredArg < NumDataArgs); 1581 S.Diag(getDataArg((unsigned) notCoveredArg)->getLocStart(), 1582 diag::warn_printf_data_arg_not_used) 1583 << getFormatStringRange(); 1584 } 1585 } 1586} 1587 1588void Sema::CheckPrintfString(const StringLiteral *FExpr, 1589 const Expr *OrigFormatExpr, 1590 const CallExpr *TheCall, bool HasVAListArg, 1591 unsigned format_idx, unsigned firstDataArg) { 1592 1593 // CHECK: is the format string a wide literal? 1594 if (FExpr->isWide()) { 1595 Diag(FExpr->getLocStart(), 1596 diag::warn_printf_format_string_is_wide_literal) 1597 << OrigFormatExpr->getSourceRange(); 1598 return; 1599 } 1600 1601 // Str - The format string. NOTE: this is NOT null-terminated! 1602 const char *Str = FExpr->getStrData(); 1603 1604 // CHECK: empty format string? 1605 unsigned StrLen = FExpr->getByteLength(); 1606 1607 if (StrLen == 0) { 1608 Diag(FExpr->getLocStart(), diag::warn_printf_empty_format_string) 1609 << OrigFormatExpr->getSourceRange(); 1610 return; 1611 } 1612 1613 CheckPrintfHandler H(*this, FExpr, OrigFormatExpr, firstDataArg, 1614 TheCall->getNumArgs() - firstDataArg, 1615 isa<ObjCStringLiteral>(OrigFormatExpr), Str, 1616 HasVAListArg, TheCall, format_idx); 1617 1618 if (!analyze_printf::ParseFormatString(H, Str, Str + StrLen)) 1619 H.DoneProcessing(); 1620} 1621 1622//===--- CHECK: Return Address of Stack Variable --------------------------===// 1623 1624static DeclRefExpr* EvalVal(Expr *E); 1625static DeclRefExpr* EvalAddr(Expr* E); 1626 1627/// CheckReturnStackAddr - Check if a return statement returns the address 1628/// of a stack variable. 1629void 1630Sema::CheckReturnStackAddr(Expr *RetValExp, QualType lhsType, 1631 SourceLocation ReturnLoc) { 1632 1633 // Perform checking for returned stack addresses. 1634 if (lhsType->isPointerType() || lhsType->isBlockPointerType()) { 1635 if (DeclRefExpr *DR = EvalAddr(RetValExp)) 1636 Diag(DR->getLocStart(), diag::warn_ret_stack_addr) 1637 << DR->getDecl()->getDeclName() << RetValExp->getSourceRange(); 1638 1639 // Skip over implicit cast expressions when checking for block expressions. 1640 RetValExp = RetValExp->IgnoreParenCasts(); 1641 1642 if (BlockExpr *C = dyn_cast<BlockExpr>(RetValExp)) 1643 if (C->hasBlockDeclRefExprs()) 1644 Diag(C->getLocStart(), diag::err_ret_local_block) 1645 << C->getSourceRange(); 1646 1647 if (AddrLabelExpr *ALE = dyn_cast<AddrLabelExpr>(RetValExp)) 1648 Diag(ALE->getLocStart(), diag::warn_ret_addr_label) 1649 << ALE->getSourceRange(); 1650 1651 } else if (lhsType->isReferenceType()) { 1652 // Perform checking for stack values returned by reference. 1653 // Check for a reference to the stack 1654 if (DeclRefExpr *DR = EvalVal(RetValExp)) 1655 Diag(DR->getLocStart(), diag::warn_ret_stack_ref) 1656 << DR->getDecl()->getDeclName() << RetValExp->getSourceRange(); 1657 } 1658} 1659 1660/// EvalAddr - EvalAddr and EvalVal are mutually recursive functions that 1661/// check if the expression in a return statement evaluates to an address 1662/// to a location on the stack. The recursion is used to traverse the 1663/// AST of the return expression, with recursion backtracking when we 1664/// encounter a subexpression that (1) clearly does not lead to the address 1665/// of a stack variable or (2) is something we cannot determine leads to 1666/// the address of a stack variable based on such local checking. 1667/// 1668/// EvalAddr processes expressions that are pointers that are used as 1669/// references (and not L-values). EvalVal handles all other values. 1670/// At the base case of the recursion is a check for a DeclRefExpr* in 1671/// the refers to a stack variable. 1672/// 1673/// This implementation handles: 1674/// 1675/// * pointer-to-pointer casts 1676/// * implicit conversions from array references to pointers 1677/// * taking the address of fields 1678/// * arbitrary interplay between "&" and "*" operators 1679/// * pointer arithmetic from an address of a stack variable 1680/// * taking the address of an array element where the array is on the stack 1681static DeclRefExpr* EvalAddr(Expr *E) { 1682 // We should only be called for evaluating pointer expressions. 1683 assert((E->getType()->isAnyPointerType() || 1684 E->getType()->isBlockPointerType() || 1685 E->getType()->isObjCQualifiedIdType()) && 1686 "EvalAddr only works on pointers"); 1687 1688 // Our "symbolic interpreter" is just a dispatch off the currently 1689 // viewed AST node. We then recursively traverse the AST by calling 1690 // EvalAddr and EvalVal appropriately. 1691 switch (E->getStmtClass()) { 1692 case Stmt::ParenExprClass: 1693 // Ignore parentheses. 1694 return EvalAddr(cast<ParenExpr>(E)->getSubExpr()); 1695 1696 case Stmt::UnaryOperatorClass: { 1697 // The only unary operator that make sense to handle here 1698 // is AddrOf. All others don't make sense as pointers. 1699 UnaryOperator *U = cast<UnaryOperator>(E); 1700 1701 if (U->getOpcode() == UnaryOperator::AddrOf) 1702 return EvalVal(U->getSubExpr()); 1703 else 1704 return NULL; 1705 } 1706 1707 case Stmt::BinaryOperatorClass: { 1708 // Handle pointer arithmetic. All other binary operators are not valid 1709 // in this context. 1710 BinaryOperator *B = cast<BinaryOperator>(E); 1711 BinaryOperator::Opcode op = B->getOpcode(); 1712 1713 if (op != BinaryOperator::Add && op != BinaryOperator::Sub) 1714 return NULL; 1715 1716 Expr *Base = B->getLHS(); 1717 1718 // Determine which argument is the real pointer base. It could be 1719 // the RHS argument instead of the LHS. 1720 if (!Base->getType()->isPointerType()) Base = B->getRHS(); 1721 1722 assert (Base->getType()->isPointerType()); 1723 return EvalAddr(Base); 1724 } 1725 1726 // For conditional operators we need to see if either the LHS or RHS are 1727 // valid DeclRefExpr*s. If one of them is valid, we return it. 1728 case Stmt::ConditionalOperatorClass: { 1729 ConditionalOperator *C = cast<ConditionalOperator>(E); 1730 1731 // Handle the GNU extension for missing LHS. 1732 if (Expr *lhsExpr = C->getLHS()) 1733 if (DeclRefExpr* LHS = EvalAddr(lhsExpr)) 1734 return LHS; 1735 1736 return EvalAddr(C->getRHS()); 1737 } 1738 1739 // For casts, we need to handle conversions from arrays to 1740 // pointer values, and pointer-to-pointer conversions. 1741 case Stmt::ImplicitCastExprClass: 1742 case Stmt::CStyleCastExprClass: 1743 case Stmt::CXXFunctionalCastExprClass: { 1744 Expr* SubExpr = cast<CastExpr>(E)->getSubExpr(); 1745 QualType T = SubExpr->getType(); 1746 1747 if (SubExpr->getType()->isPointerType() || 1748 SubExpr->getType()->isBlockPointerType() || 1749 SubExpr->getType()->isObjCQualifiedIdType()) 1750 return EvalAddr(SubExpr); 1751 else if (T->isArrayType()) 1752 return EvalVal(SubExpr); 1753 else 1754 return 0; 1755 } 1756 1757 // C++ casts. For dynamic casts, static casts, and const casts, we 1758 // are always converting from a pointer-to-pointer, so we just blow 1759 // through the cast. In the case the dynamic cast doesn't fail (and 1760 // return NULL), we take the conservative route and report cases 1761 // where we return the address of a stack variable. For Reinterpre 1762 // FIXME: The comment about is wrong; we're not always converting 1763 // from pointer to pointer. I'm guessing that this code should also 1764 // handle references to objects. 1765 case Stmt::CXXStaticCastExprClass: 1766 case Stmt::CXXDynamicCastExprClass: 1767 case Stmt::CXXConstCastExprClass: 1768 case Stmt::CXXReinterpretCastExprClass: { 1769 Expr *S = cast<CXXNamedCastExpr>(E)->getSubExpr(); 1770 if (S->getType()->isPointerType() || S->getType()->isBlockPointerType()) 1771 return EvalAddr(S); 1772 else 1773 return NULL; 1774 } 1775 1776 // Everything else: we simply don't reason about them. 1777 default: 1778 return NULL; 1779 } 1780} 1781 1782 1783/// EvalVal - This function is complements EvalAddr in the mutual recursion. 1784/// See the comments for EvalAddr for more details. 1785static DeclRefExpr* EvalVal(Expr *E) { 1786 1787 // We should only be called for evaluating non-pointer expressions, or 1788 // expressions with a pointer type that are not used as references but instead 1789 // are l-values (e.g., DeclRefExpr with a pointer type). 1790 1791 // Our "symbolic interpreter" is just a dispatch off the currently 1792 // viewed AST node. We then recursively traverse the AST by calling 1793 // EvalAddr and EvalVal appropriately. 1794 switch (E->getStmtClass()) { 1795 case Stmt::DeclRefExprClass: { 1796 // DeclRefExpr: the base case. When we hit a DeclRefExpr we are looking 1797 // at code that refers to a variable's name. We check if it has local 1798 // storage within the function, and if so, return the expression. 1799 DeclRefExpr *DR = cast<DeclRefExpr>(E); 1800 1801 if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl())) 1802 if (V->hasLocalStorage() && !V->getType()->isReferenceType()) return DR; 1803 1804 return NULL; 1805 } 1806 1807 case Stmt::ParenExprClass: 1808 // Ignore parentheses. 1809 return EvalVal(cast<ParenExpr>(E)->getSubExpr()); 1810 1811 case Stmt::UnaryOperatorClass: { 1812 // The only unary operator that make sense to handle here 1813 // is Deref. All others don't resolve to a "name." This includes 1814 // handling all sorts of rvalues passed to a unary operator. 1815 UnaryOperator *U = cast<UnaryOperator>(E); 1816 1817 if (U->getOpcode() == UnaryOperator::Deref) 1818 return EvalAddr(U->getSubExpr()); 1819 1820 return NULL; 1821 } 1822 1823 case Stmt::ArraySubscriptExprClass: { 1824 // Array subscripts are potential references to data on the stack. We 1825 // retrieve the DeclRefExpr* for the array variable if it indeed 1826 // has local storage. 1827 return EvalAddr(cast<ArraySubscriptExpr>(E)->getBase()); 1828 } 1829 1830 case Stmt::ConditionalOperatorClass: { 1831 // For conditional operators we need to see if either the LHS or RHS are 1832 // non-NULL DeclRefExpr's. If one is non-NULL, we return it. 1833 ConditionalOperator *C = cast<ConditionalOperator>(E); 1834 1835 // Handle the GNU extension for missing LHS. 1836 if (Expr *lhsExpr = C->getLHS()) 1837 if (DeclRefExpr *LHS = EvalVal(lhsExpr)) 1838 return LHS; 1839 1840 return EvalVal(C->getRHS()); 1841 } 1842 1843 // Accesses to members are potential references to data on the stack. 1844 case Stmt::MemberExprClass: { 1845 MemberExpr *M = cast<MemberExpr>(E); 1846 1847 // Check for indirect access. We only want direct field accesses. 1848 if (!M->isArrow()) 1849 return EvalVal(M->getBase()); 1850 else 1851 return NULL; 1852 } 1853 1854 // Everything else: we simply don't reason about them. 1855 default: 1856 return NULL; 1857 } 1858} 1859 1860//===--- CHECK: Floating-Point comparisons (-Wfloat-equal) ---------------===// 1861 1862/// Check for comparisons of floating point operands using != and ==. 1863/// Issue a warning if these are no self-comparisons, as they are not likely 1864/// to do what the programmer intended. 1865void Sema::CheckFloatComparison(SourceLocation loc, Expr* lex, Expr *rex) { 1866 bool EmitWarning = true; 1867 1868 Expr* LeftExprSansParen = lex->IgnoreParens(); 1869 Expr* RightExprSansParen = rex->IgnoreParens(); 1870 1871 // Special case: check for x == x (which is OK). 1872 // Do not emit warnings for such cases. 1873 if (DeclRefExpr* DRL = dyn_cast<DeclRefExpr>(LeftExprSansParen)) 1874 if (DeclRefExpr* DRR = dyn_cast<DeclRefExpr>(RightExprSansParen)) 1875 if (DRL->getDecl() == DRR->getDecl()) 1876 EmitWarning = false; 1877 1878 1879 // Special case: check for comparisons against literals that can be exactly 1880 // represented by APFloat. In such cases, do not emit a warning. This 1881 // is a heuristic: often comparison against such literals are used to 1882 // detect if a value in a variable has not changed. This clearly can 1883 // lead to false negatives. 1884 if (EmitWarning) { 1885 if (FloatingLiteral* FLL = dyn_cast<FloatingLiteral>(LeftExprSansParen)) { 1886 if (FLL->isExact()) 1887 EmitWarning = false; 1888 } else 1889 if (FloatingLiteral* FLR = dyn_cast<FloatingLiteral>(RightExprSansParen)){ 1890 if (FLR->isExact()) 1891 EmitWarning = false; 1892 } 1893 } 1894 1895 // Check for comparisons with builtin types. 1896 if (EmitWarning) 1897 if (CallExpr* CL = dyn_cast<CallExpr>(LeftExprSansParen)) 1898 if (CL->isBuiltinCall(Context)) 1899 EmitWarning = false; 1900 1901 if (EmitWarning) 1902 if (CallExpr* CR = dyn_cast<CallExpr>(RightExprSansParen)) 1903 if (CR->isBuiltinCall(Context)) 1904 EmitWarning = false; 1905 1906 // Emit the diagnostic. 1907 if (EmitWarning) 1908 Diag(loc, diag::warn_floatingpoint_eq) 1909 << lex->getSourceRange() << rex->getSourceRange(); 1910} 1911 1912//===--- CHECK: Integer mixed-sign comparisons (-Wsign-compare) --------===// 1913//===--- CHECK: Lossy implicit conversions (-Wconversion) --------------===// 1914 1915namespace { 1916 1917/// Structure recording the 'active' range of an integer-valued 1918/// expression. 1919struct IntRange { 1920 /// The number of bits active in the int. 1921 unsigned Width; 1922 1923 /// True if the int is known not to have negative values. 1924 bool NonNegative; 1925 1926 IntRange() {} 1927 IntRange(unsigned Width, bool NonNegative) 1928 : Width(Width), NonNegative(NonNegative) 1929 {} 1930 1931 // Returns the range of the bool type. 1932 static IntRange forBoolType() { 1933 return IntRange(1, true); 1934 } 1935 1936 // Returns the range of an integral type. 1937 static IntRange forType(ASTContext &C, QualType T) { 1938 return forCanonicalType(C, T->getCanonicalTypeInternal().getTypePtr()); 1939 } 1940 1941 // Returns the range of an integeral type based on its canonical 1942 // representation. 1943 static IntRange forCanonicalType(ASTContext &C, const Type *T) { 1944 assert(T->isCanonicalUnqualified()); 1945 1946 if (const VectorType *VT = dyn_cast<VectorType>(T)) 1947 T = VT->getElementType().getTypePtr(); 1948 if (const ComplexType *CT = dyn_cast<ComplexType>(T)) 1949 T = CT->getElementType().getTypePtr(); 1950 1951 if (const EnumType *ET = dyn_cast<EnumType>(T)) { 1952 EnumDecl *Enum = ET->getDecl(); 1953 unsigned NumPositive = Enum->getNumPositiveBits(); 1954 unsigned NumNegative = Enum->getNumNegativeBits(); 1955 1956 return IntRange(std::max(NumPositive, NumNegative), NumNegative == 0); 1957 } 1958 1959 const BuiltinType *BT = cast<BuiltinType>(T); 1960 assert(BT->isInteger()); 1961 1962 return IntRange(C.getIntWidth(QualType(T, 0)), BT->isUnsignedInteger()); 1963 } 1964 1965 // Returns the supremum of two ranges: i.e. their conservative merge. 1966 static IntRange join(IntRange L, IntRange R) { 1967 return IntRange(std::max(L.Width, R.Width), 1968 L.NonNegative && R.NonNegative); 1969 } 1970 1971 // Returns the infinum of two ranges: i.e. their aggressive merge. 1972 static IntRange meet(IntRange L, IntRange R) { 1973 return IntRange(std::min(L.Width, R.Width), 1974 L.NonNegative || R.NonNegative); 1975 } 1976}; 1977 1978IntRange GetValueRange(ASTContext &C, llvm::APSInt &value, unsigned MaxWidth) { 1979 if (value.isSigned() && value.isNegative()) 1980 return IntRange(value.getMinSignedBits(), false); 1981 1982 if (value.getBitWidth() > MaxWidth) 1983 value.trunc(MaxWidth); 1984 1985 // isNonNegative() just checks the sign bit without considering 1986 // signedness. 1987 return IntRange(value.getActiveBits(), true); 1988} 1989 1990IntRange GetValueRange(ASTContext &C, APValue &result, QualType Ty, 1991 unsigned MaxWidth) { 1992 if (result.isInt()) 1993 return GetValueRange(C, result.getInt(), MaxWidth); 1994 1995 if (result.isVector()) { 1996 IntRange R = GetValueRange(C, result.getVectorElt(0), Ty, MaxWidth); 1997 for (unsigned i = 1, e = result.getVectorLength(); i != e; ++i) { 1998 IntRange El = GetValueRange(C, result.getVectorElt(i), Ty, MaxWidth); 1999 R = IntRange::join(R, El); 2000 } 2001 return R; 2002 } 2003 2004 if (result.isComplexInt()) { 2005 IntRange R = GetValueRange(C, result.getComplexIntReal(), MaxWidth); 2006 IntRange I = GetValueRange(C, result.getComplexIntImag(), MaxWidth); 2007 return IntRange::join(R, I); 2008 } 2009 2010 // This can happen with lossless casts to intptr_t of "based" lvalues. 2011 // Assume it might use arbitrary bits. 2012 // FIXME: The only reason we need to pass the type in here is to get 2013 // the sign right on this one case. It would be nice if APValue 2014 // preserved this. 2015 assert(result.isLValue()); 2016 return IntRange(MaxWidth, Ty->isUnsignedIntegerType()); 2017} 2018 2019/// Pseudo-evaluate the given integer expression, estimating the 2020/// range of values it might take. 2021/// 2022/// \param MaxWidth - the width to which the value will be truncated 2023IntRange GetExprRange(ASTContext &C, Expr *E, unsigned MaxWidth) { 2024 E = E->IgnoreParens(); 2025 2026 // Try a full evaluation first. 2027 Expr::EvalResult result; 2028 if (E->Evaluate(result, C)) 2029 return GetValueRange(C, result.Val, E->getType(), MaxWidth); 2030 2031 // I think we only want to look through implicit casts here; if the 2032 // user has an explicit widening cast, we should treat the value as 2033 // being of the new, wider type. 2034 if (ImplicitCastExpr *CE = dyn_cast<ImplicitCastExpr>(E)) { 2035 if (CE->getCastKind() == CastExpr::CK_NoOp) 2036 return GetExprRange(C, CE->getSubExpr(), MaxWidth); 2037 2038 IntRange OutputTypeRange = IntRange::forType(C, CE->getType()); 2039 2040 bool isIntegerCast = (CE->getCastKind() == CastExpr::CK_IntegralCast); 2041 if (!isIntegerCast && CE->getCastKind() == CastExpr::CK_Unknown) 2042 isIntegerCast = CE->getSubExpr()->getType()->isIntegerType(); 2043 2044 // Assume that non-integer casts can span the full range of the type. 2045 if (!isIntegerCast) 2046 return OutputTypeRange; 2047 2048 IntRange SubRange 2049 = GetExprRange(C, CE->getSubExpr(), 2050 std::min(MaxWidth, OutputTypeRange.Width)); 2051 2052 // Bail out if the subexpr's range is as wide as the cast type. 2053 if (SubRange.Width >= OutputTypeRange.Width) 2054 return OutputTypeRange; 2055 2056 // Otherwise, we take the smaller width, and we're non-negative if 2057 // either the output type or the subexpr is. 2058 return IntRange(SubRange.Width, 2059 SubRange.NonNegative || OutputTypeRange.NonNegative); 2060 } 2061 2062 if (ConditionalOperator *CO = dyn_cast<ConditionalOperator>(E)) { 2063 // If we can fold the condition, just take that operand. 2064 bool CondResult; 2065 if (CO->getCond()->EvaluateAsBooleanCondition(CondResult, C)) 2066 return GetExprRange(C, CondResult ? CO->getTrueExpr() 2067 : CO->getFalseExpr(), 2068 MaxWidth); 2069 2070 // Otherwise, conservatively merge. 2071 IntRange L = GetExprRange(C, CO->getTrueExpr(), MaxWidth); 2072 IntRange R = GetExprRange(C, CO->getFalseExpr(), MaxWidth); 2073 return IntRange::join(L, R); 2074 } 2075 2076 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) { 2077 switch (BO->getOpcode()) { 2078 2079 // Boolean-valued operations are single-bit and positive. 2080 case BinaryOperator::LAnd: 2081 case BinaryOperator::LOr: 2082 case BinaryOperator::LT: 2083 case BinaryOperator::GT: 2084 case BinaryOperator::LE: 2085 case BinaryOperator::GE: 2086 case BinaryOperator::EQ: 2087 case BinaryOperator::NE: 2088 return IntRange::forBoolType(); 2089 2090 // The type of these compound assignments is the type of the LHS, 2091 // so the RHS is not necessarily an integer. 2092 case BinaryOperator::MulAssign: 2093 case BinaryOperator::DivAssign: 2094 case BinaryOperator::RemAssign: 2095 case BinaryOperator::AddAssign: 2096 case BinaryOperator::SubAssign: 2097 return IntRange::forType(C, E->getType()); 2098 2099 // Operations with opaque sources are black-listed. 2100 case BinaryOperator::PtrMemD: 2101 case BinaryOperator::PtrMemI: 2102 return IntRange::forType(C, E->getType()); 2103 2104 // Bitwise-and uses the *infinum* of the two source ranges. 2105 case BinaryOperator::And: 2106 case BinaryOperator::AndAssign: 2107 return IntRange::meet(GetExprRange(C, BO->getLHS(), MaxWidth), 2108 GetExprRange(C, BO->getRHS(), MaxWidth)); 2109 2110 // Left shift gets black-listed based on a judgement call. 2111 case BinaryOperator::Shl: 2112 // ...except that we want to treat '1 << (blah)' as logically 2113 // positive. It's an important idiom. 2114 if (IntegerLiteral *I 2115 = dyn_cast<IntegerLiteral>(BO->getLHS()->IgnoreParenCasts())) { 2116 if (I->getValue() == 1) { 2117 IntRange R = IntRange::forType(C, E->getType()); 2118 return IntRange(R.Width, /*NonNegative*/ true); 2119 } 2120 } 2121 // fallthrough 2122 2123 case BinaryOperator::ShlAssign: 2124 return IntRange::forType(C, E->getType()); 2125 2126 // Right shift by a constant can narrow its left argument. 2127 case BinaryOperator::Shr: 2128 case BinaryOperator::ShrAssign: { 2129 IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth); 2130 2131 // If the shift amount is a positive constant, drop the width by 2132 // that much. 2133 llvm::APSInt shift; 2134 if (BO->getRHS()->isIntegerConstantExpr(shift, C) && 2135 shift.isNonNegative()) { 2136 unsigned zext = shift.getZExtValue(); 2137 if (zext >= L.Width) 2138 L.Width = (L.NonNegative ? 0 : 1); 2139 else 2140 L.Width -= zext; 2141 } 2142 2143 return L; 2144 } 2145 2146 // Comma acts as its right operand. 2147 case BinaryOperator::Comma: 2148 return GetExprRange(C, BO->getRHS(), MaxWidth); 2149 2150 // Black-list pointer subtractions. 2151 case BinaryOperator::Sub: 2152 if (BO->getLHS()->getType()->isPointerType()) 2153 return IntRange::forType(C, E->getType()); 2154 // fallthrough 2155 2156 default: 2157 break; 2158 } 2159 2160 // Treat every other operator as if it were closed on the 2161 // narrowest type that encompasses both operands. 2162 IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth); 2163 IntRange R = GetExprRange(C, BO->getRHS(), MaxWidth); 2164 return IntRange::join(L, R); 2165 } 2166 2167 if (UnaryOperator *UO = dyn_cast<UnaryOperator>(E)) { 2168 switch (UO->getOpcode()) { 2169 // Boolean-valued operations are white-listed. 2170 case UnaryOperator::LNot: 2171 return IntRange::forBoolType(); 2172 2173 // Operations with opaque sources are black-listed. 2174 case UnaryOperator::Deref: 2175 case UnaryOperator::AddrOf: // should be impossible 2176 case UnaryOperator::OffsetOf: 2177 return IntRange::forType(C, E->getType()); 2178 2179 default: 2180 return GetExprRange(C, UO->getSubExpr(), MaxWidth); 2181 } 2182 } 2183 2184 if (dyn_cast<OffsetOfExpr>(E)) { 2185 IntRange::forType(C, E->getType()); 2186 } 2187 2188 FieldDecl *BitField = E->getBitField(); 2189 if (BitField) { 2190 llvm::APSInt BitWidthAP = BitField->getBitWidth()->EvaluateAsInt(C); 2191 unsigned BitWidth = BitWidthAP.getZExtValue(); 2192 2193 return IntRange(BitWidth, BitField->getType()->isUnsignedIntegerType()); 2194 } 2195 2196 return IntRange::forType(C, E->getType()); 2197} 2198 2199IntRange GetExprRange(ASTContext &C, Expr *E) { 2200 return GetExprRange(C, E, C.getIntWidth(E->getType())); 2201} 2202 2203/// Checks whether the given value, which currently has the given 2204/// source semantics, has the same value when coerced through the 2205/// target semantics. 2206bool IsSameFloatAfterCast(const llvm::APFloat &value, 2207 const llvm::fltSemantics &Src, 2208 const llvm::fltSemantics &Tgt) { 2209 llvm::APFloat truncated = value; 2210 2211 bool ignored; 2212 truncated.convert(Src, llvm::APFloat::rmNearestTiesToEven, &ignored); 2213 truncated.convert(Tgt, llvm::APFloat::rmNearestTiesToEven, &ignored); 2214 2215 return truncated.bitwiseIsEqual(value); 2216} 2217 2218/// Checks whether the given value, which currently has the given 2219/// source semantics, has the same value when coerced through the 2220/// target semantics. 2221/// 2222/// The value might be a vector of floats (or a complex number). 2223bool IsSameFloatAfterCast(const APValue &value, 2224 const llvm::fltSemantics &Src, 2225 const llvm::fltSemantics &Tgt) { 2226 if (value.isFloat()) 2227 return IsSameFloatAfterCast(value.getFloat(), Src, Tgt); 2228 2229 if (value.isVector()) { 2230 for (unsigned i = 0, e = value.getVectorLength(); i != e; ++i) 2231 if (!IsSameFloatAfterCast(value.getVectorElt(i), Src, Tgt)) 2232 return false; 2233 return true; 2234 } 2235 2236 assert(value.isComplexFloat()); 2237 return (IsSameFloatAfterCast(value.getComplexFloatReal(), Src, Tgt) && 2238 IsSameFloatAfterCast(value.getComplexFloatImag(), Src, Tgt)); 2239} 2240 2241void AnalyzeImplicitConversions(Sema &S, Expr *E); 2242 2243bool IsZero(Sema &S, Expr *E) { 2244 llvm::APSInt Value; 2245 return E->isIntegerConstantExpr(Value, S.Context) && Value == 0; 2246} 2247 2248void CheckTrivialUnsignedComparison(Sema &S, BinaryOperator *E) { 2249 BinaryOperator::Opcode op = E->getOpcode(); 2250 if (op == BinaryOperator::LT && IsZero(S, E->getRHS())) { 2251 S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison) 2252 << "< 0" << "false" 2253 << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); 2254 } else if (op == BinaryOperator::GE && IsZero(S, E->getRHS())) { 2255 S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison) 2256 << ">= 0" << "true" 2257 << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); 2258 } else if (op == BinaryOperator::GT && IsZero(S, E->getLHS())) { 2259 S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison) 2260 << "0 >" << "false" 2261 << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); 2262 } else if (op == BinaryOperator::LE && IsZero(S, E->getLHS())) { 2263 S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison) 2264 << "0 <=" << "true" 2265 << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); 2266 } 2267} 2268 2269/// Analyze the operands of the given comparison. Implements the 2270/// fallback case from AnalyzeComparison. 2271void AnalyzeImpConvsInComparison(Sema &S, BinaryOperator *E) { 2272 AnalyzeImplicitConversions(S, E->getLHS()); 2273 AnalyzeImplicitConversions(S, E->getRHS()); 2274} 2275 2276/// \brief Implements -Wsign-compare. 2277/// 2278/// \param lex the left-hand expression 2279/// \param rex the right-hand expression 2280/// \param OpLoc the location of the joining operator 2281/// \param BinOpc binary opcode or 0 2282void AnalyzeComparison(Sema &S, BinaryOperator *E) { 2283 // The type the comparison is being performed in. 2284 QualType T = E->getLHS()->getType(); 2285 assert(S.Context.hasSameUnqualifiedType(T, E->getRHS()->getType()) 2286 && "comparison with mismatched types"); 2287 2288 // We don't do anything special if this isn't an unsigned integral 2289 // comparison: we're only interested in integral comparisons, and 2290 // signed comparisons only happen in cases we don't care to warn about. 2291 if (!T->isUnsignedIntegerType()) 2292 return AnalyzeImpConvsInComparison(S, E); 2293 2294 Expr *lex = E->getLHS()->IgnoreParenImpCasts(); 2295 Expr *rex = E->getRHS()->IgnoreParenImpCasts(); 2296 2297 // Check to see if one of the (unmodified) operands is of different 2298 // signedness. 2299 Expr *signedOperand, *unsignedOperand; 2300 if (lex->getType()->isSignedIntegerType()) { 2301 assert(!rex->getType()->isSignedIntegerType() && 2302 "unsigned comparison between two signed integer expressions?"); 2303 signedOperand = lex; 2304 unsignedOperand = rex; 2305 } else if (rex->getType()->isSignedIntegerType()) { 2306 signedOperand = rex; 2307 unsignedOperand = lex; 2308 } else { 2309 CheckTrivialUnsignedComparison(S, E); 2310 return AnalyzeImpConvsInComparison(S, E); 2311 } 2312 2313 // Otherwise, calculate the effective range of the signed operand. 2314 IntRange signedRange = GetExprRange(S.Context, signedOperand); 2315 2316 // Go ahead and analyze implicit conversions in the operands. Note 2317 // that we skip the implicit conversions on both sides. 2318 AnalyzeImplicitConversions(S, lex); 2319 AnalyzeImplicitConversions(S, rex); 2320 2321 // If the signed range is non-negative, -Wsign-compare won't fire, 2322 // but we should still check for comparisons which are always true 2323 // or false. 2324 if (signedRange.NonNegative) 2325 return CheckTrivialUnsignedComparison(S, E); 2326 2327 // For (in)equality comparisons, if the unsigned operand is a 2328 // constant which cannot collide with a overflowed signed operand, 2329 // then reinterpreting the signed operand as unsigned will not 2330 // change the result of the comparison. 2331 if (E->isEqualityOp()) { 2332 unsigned comparisonWidth = S.Context.getIntWidth(T); 2333 IntRange unsignedRange = GetExprRange(S.Context, unsignedOperand); 2334 2335 // We should never be unable to prove that the unsigned operand is 2336 // non-negative. 2337 assert(unsignedRange.NonNegative && "unsigned range includes negative?"); 2338 2339 if (unsignedRange.Width < comparisonWidth) 2340 return; 2341 } 2342 2343 S.Diag(E->getOperatorLoc(), diag::warn_mixed_sign_comparison) 2344 << lex->getType() << rex->getType() 2345 << lex->getSourceRange() << rex->getSourceRange(); 2346} 2347 2348/// Diagnose an implicit cast; purely a helper for CheckImplicitConversion. 2349void DiagnoseImpCast(Sema &S, Expr *E, QualType T, unsigned diag) { 2350 S.Diag(E->getExprLoc(), diag) << E->getType() << T << E->getSourceRange(); 2351} 2352 2353void CheckImplicitConversion(Sema &S, Expr *E, QualType T, 2354 bool *ICContext = 0) { 2355 if (E->isTypeDependent() || E->isValueDependent()) return; 2356 2357 const Type *Source = S.Context.getCanonicalType(E->getType()).getTypePtr(); 2358 const Type *Target = S.Context.getCanonicalType(T).getTypePtr(); 2359 if (Source == Target) return; 2360 if (Target->isDependentType()) return; 2361 2362 // Never diagnose implicit casts to bool. 2363 if (Target->isSpecificBuiltinType(BuiltinType::Bool)) 2364 return; 2365 2366 // Strip vector types. 2367 if (isa<VectorType>(Source)) { 2368 if (!isa<VectorType>(Target)) 2369 return DiagnoseImpCast(S, E, T, diag::warn_impcast_vector_scalar); 2370 2371 Source = cast<VectorType>(Source)->getElementType().getTypePtr(); 2372 Target = cast<VectorType>(Target)->getElementType().getTypePtr(); 2373 } 2374 2375 // Strip complex types. 2376 if (isa<ComplexType>(Source)) { 2377 if (!isa<ComplexType>(Target)) 2378 return DiagnoseImpCast(S, E, T, diag::warn_impcast_complex_scalar); 2379 2380 Source = cast<ComplexType>(Source)->getElementType().getTypePtr(); 2381 Target = cast<ComplexType>(Target)->getElementType().getTypePtr(); 2382 } 2383 2384 const BuiltinType *SourceBT = dyn_cast<BuiltinType>(Source); 2385 const BuiltinType *TargetBT = dyn_cast<BuiltinType>(Target); 2386 2387 // If the source is floating point... 2388 if (SourceBT && SourceBT->isFloatingPoint()) { 2389 // ...and the target is floating point... 2390 if (TargetBT && TargetBT->isFloatingPoint()) { 2391 // ...then warn if we're dropping FP rank. 2392 2393 // Builtin FP kinds are ordered by increasing FP rank. 2394 if (SourceBT->getKind() > TargetBT->getKind()) { 2395 // Don't warn about float constants that are precisely 2396 // representable in the target type. 2397 Expr::EvalResult result; 2398 if (E->Evaluate(result, S.Context)) { 2399 // Value might be a float, a float vector, or a float complex. 2400 if (IsSameFloatAfterCast(result.Val, 2401 S.Context.getFloatTypeSemantics(QualType(TargetBT, 0)), 2402 S.Context.getFloatTypeSemantics(QualType(SourceBT, 0)))) 2403 return; 2404 } 2405 2406 DiagnoseImpCast(S, E, T, diag::warn_impcast_float_precision); 2407 } 2408 return; 2409 } 2410 2411 // If the target is integral, always warn. 2412 if ((TargetBT && TargetBT->isInteger())) 2413 // TODO: don't warn for integer values? 2414 DiagnoseImpCast(S, E, T, diag::warn_impcast_float_integer); 2415 2416 return; 2417 } 2418 2419 if (!Source->isIntegerType() || !Target->isIntegerType()) 2420 return; 2421 2422 IntRange SourceRange = GetExprRange(S.Context, E); 2423 IntRange TargetRange = IntRange::forCanonicalType(S.Context, Target); 2424 2425 if (SourceRange.Width > TargetRange.Width) { 2426 // People want to build with -Wshorten-64-to-32 and not -Wconversion 2427 // and by god we'll let them. 2428 if (SourceRange.Width == 64 && TargetRange.Width == 32) 2429 return DiagnoseImpCast(S, E, T, diag::warn_impcast_integer_64_32); 2430 return DiagnoseImpCast(S, E, T, diag::warn_impcast_integer_precision); 2431 } 2432 2433 if ((TargetRange.NonNegative && !SourceRange.NonNegative) || 2434 (!TargetRange.NonNegative && SourceRange.NonNegative && 2435 SourceRange.Width == TargetRange.Width)) { 2436 unsigned DiagID = diag::warn_impcast_integer_sign; 2437 2438 // Traditionally, gcc has warned about this under -Wsign-compare. 2439 // We also want to warn about it in -Wconversion. 2440 // So if -Wconversion is off, use a completely identical diagnostic 2441 // in the sign-compare group. 2442 // The conditional-checking code will 2443 if (ICContext) { 2444 DiagID = diag::warn_impcast_integer_sign_conditional; 2445 *ICContext = true; 2446 } 2447 2448 return DiagnoseImpCast(S, E, T, DiagID); 2449 } 2450 2451 return; 2452} 2453 2454void CheckConditionalOperator(Sema &S, ConditionalOperator *E, QualType T); 2455 2456void CheckConditionalOperand(Sema &S, Expr *E, QualType T, 2457 bool &ICContext) { 2458 E = E->IgnoreParenImpCasts(); 2459 2460 if (isa<ConditionalOperator>(E)) 2461 return CheckConditionalOperator(S, cast<ConditionalOperator>(E), T); 2462 2463 AnalyzeImplicitConversions(S, E); 2464 if (E->getType() != T) 2465 return CheckImplicitConversion(S, E, T, &ICContext); 2466 return; 2467} 2468 2469void CheckConditionalOperator(Sema &S, ConditionalOperator *E, QualType T) { 2470 AnalyzeImplicitConversions(S, E->getCond()); 2471 2472 bool Suspicious = false; 2473 CheckConditionalOperand(S, E->getTrueExpr(), T, Suspicious); 2474 CheckConditionalOperand(S, E->getFalseExpr(), T, Suspicious); 2475 2476 // If -Wconversion would have warned about either of the candidates 2477 // for a signedness conversion to the context type... 2478 if (!Suspicious) return; 2479 2480 // ...but it's currently ignored... 2481 if (S.Diags.getDiagnosticLevel(diag::warn_impcast_integer_sign_conditional)) 2482 return; 2483 2484 // ...and -Wsign-compare isn't... 2485 if (!S.Diags.getDiagnosticLevel(diag::warn_mixed_sign_conditional)) 2486 return; 2487 2488 // ...then check whether it would have warned about either of the 2489 // candidates for a signedness conversion to the condition type. 2490 if (E->getType() != T) { 2491 Suspicious = false; 2492 CheckImplicitConversion(S, E->getTrueExpr()->IgnoreParenImpCasts(), 2493 E->getType(), &Suspicious); 2494 if (!Suspicious) 2495 CheckImplicitConversion(S, E->getFalseExpr()->IgnoreParenImpCasts(), 2496 E->getType(), &Suspicious); 2497 if (!Suspicious) 2498 return; 2499 } 2500 2501 // If so, emit a diagnostic under -Wsign-compare. 2502 Expr *lex = E->getTrueExpr()->IgnoreParenImpCasts(); 2503 Expr *rex = E->getFalseExpr()->IgnoreParenImpCasts(); 2504 S.Diag(E->getQuestionLoc(), diag::warn_mixed_sign_conditional) 2505 << lex->getType() << rex->getType() 2506 << lex->getSourceRange() << rex->getSourceRange(); 2507} 2508 2509/// AnalyzeImplicitConversions - Find and report any interesting 2510/// implicit conversions in the given expression. There are a couple 2511/// of competing diagnostics here, -Wconversion and -Wsign-compare. 2512void AnalyzeImplicitConversions(Sema &S, Expr *OrigE) { 2513 QualType T = OrigE->getType(); 2514 Expr *E = OrigE->IgnoreParenImpCasts(); 2515 2516 // For conditional operators, we analyze the arguments as if they 2517 // were being fed directly into the output. 2518 if (isa<ConditionalOperator>(E)) { 2519 ConditionalOperator *CO = cast<ConditionalOperator>(E); 2520 CheckConditionalOperator(S, CO, T); 2521 return; 2522 } 2523 2524 // Go ahead and check any implicit conversions we might have skipped. 2525 // The non-canonical typecheck is just an optimization; 2526 // CheckImplicitConversion will filter out dead implicit conversions. 2527 if (E->getType() != T) 2528 CheckImplicitConversion(S, E, T); 2529 2530 // Now continue drilling into this expression. 2531 2532 // Skip past explicit casts. 2533 if (isa<ExplicitCastExpr>(E)) { 2534 E = cast<ExplicitCastExpr>(E)->getSubExpr()->IgnoreParenImpCasts(); 2535 return AnalyzeImplicitConversions(S, E); 2536 } 2537 2538 // Do a somewhat different check with comparison operators. 2539 if (isa<BinaryOperator>(E) && cast<BinaryOperator>(E)->isComparisonOp()) 2540 return AnalyzeComparison(S, cast<BinaryOperator>(E)); 2541 2542 // These break the otherwise-useful invariant below. Fortunately, 2543 // we don't really need to recurse into them, because any internal 2544 // expressions should have been analyzed already when they were 2545 // built into statements. 2546 if (isa<StmtExpr>(E)) return; 2547 2548 // Don't descend into unevaluated contexts. 2549 if (isa<SizeOfAlignOfExpr>(E)) return; 2550 2551 // Now just recurse over the expression's children. 2552 for (Stmt::child_iterator I = E->child_begin(), IE = E->child_end(); 2553 I != IE; ++I) 2554 AnalyzeImplicitConversions(S, cast<Expr>(*I)); 2555} 2556 2557} // end anonymous namespace 2558 2559/// Diagnoses "dangerous" implicit conversions within the given 2560/// expression (which is a full expression). Implements -Wconversion 2561/// and -Wsign-compare. 2562void Sema::CheckImplicitConversions(Expr *E) { 2563 // Don't diagnose in unevaluated contexts. 2564 if (ExprEvalContexts.back().Context == Sema::Unevaluated) 2565 return; 2566 2567 // Don't diagnose for value- or type-dependent expressions. 2568 if (E->isTypeDependent() || E->isValueDependent()) 2569 return; 2570 2571 AnalyzeImplicitConversions(*this, E); 2572} 2573 2574/// CheckParmsForFunctionDef - Check that the parameters of the given 2575/// function are appropriate for the definition of a function. This 2576/// takes care of any checks that cannot be performed on the 2577/// declaration itself, e.g., that the types of each of the function 2578/// parameters are complete. 2579bool Sema::CheckParmsForFunctionDef(FunctionDecl *FD) { 2580 bool HasInvalidParm = false; 2581 for (unsigned p = 0, NumParams = FD->getNumParams(); p < NumParams; ++p) { 2582 ParmVarDecl *Param = FD->getParamDecl(p); 2583 2584 // C99 6.7.5.3p4: the parameters in a parameter type list in a 2585 // function declarator that is part of a function definition of 2586 // that function shall not have incomplete type. 2587 // 2588 // This is also C++ [dcl.fct]p6. 2589 if (!Param->isInvalidDecl() && 2590 RequireCompleteType(Param->getLocation(), Param->getType(), 2591 diag::err_typecheck_decl_incomplete_type)) { 2592 Param->setInvalidDecl(); 2593 HasInvalidParm = true; 2594 } 2595 2596 // C99 6.9.1p5: If the declarator includes a parameter type list, the 2597 // declaration of each parameter shall include an identifier. 2598 if (Param->getIdentifier() == 0 && 2599 !Param->isImplicit() && 2600 !getLangOptions().CPlusPlus) 2601 Diag(Param->getLocation(), diag::err_parameter_name_omitted); 2602 2603 // C99 6.7.5.3p12: 2604 // If the function declarator is not part of a definition of that 2605 // function, parameters may have incomplete type and may use the [*] 2606 // notation in their sequences of declarator specifiers to specify 2607 // variable length array types. 2608 QualType PType = Param->getOriginalType(); 2609 if (const ArrayType *AT = Context.getAsArrayType(PType)) { 2610 if (AT->getSizeModifier() == ArrayType::Star) { 2611 // FIXME: This diagnosic should point the the '[*]' if source-location 2612 // information is added for it. 2613 Diag(Param->getLocation(), diag::err_array_star_in_function_definition); 2614 } 2615 } 2616 } 2617 2618 return HasInvalidParm; 2619} 2620