SemaChecking.cpp revision 826a3457f737f1fc45a22954fd1bfde38160c165
1//===--- SemaChecking.cpp - Extra Semantic Checking -----------------------===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This file implements extra semantic analysis beyond what is enforced 11// by the C type system. 12// 13//===----------------------------------------------------------------------===// 14 15#include "Sema.h" 16#include "clang/Analysis/Analyses/FormatString.h" 17#include "clang/AST/ASTContext.h" 18#include "clang/AST/CharUnits.h" 19#include "clang/AST/DeclObjC.h" 20#include "clang/AST/ExprCXX.h" 21#include "clang/AST/ExprObjC.h" 22#include "clang/AST/DeclObjC.h" 23#include "clang/AST/StmtCXX.h" 24#include "clang/AST/StmtObjC.h" 25#include "clang/Lex/LiteralSupport.h" 26#include "clang/Lex/Preprocessor.h" 27#include "llvm/ADT/BitVector.h" 28#include "llvm/ADT/STLExtras.h" 29#include "llvm/ADT/StringExtras.h" 30#include "llvm/Support/raw_ostream.h" 31#include "clang/Basic/TargetBuiltins.h" 32#include "clang/Basic/TargetInfo.h" 33#include <limits> 34using namespace clang; 35 36/// getLocationOfStringLiteralByte - Return a source location that points to the 37/// specified byte of the specified string literal. 38/// 39/// Strings are amazingly complex. They can be formed from multiple tokens and 40/// can have escape sequences in them in addition to the usual trigraph and 41/// escaped newline business. This routine handles this complexity. 42/// 43SourceLocation Sema::getLocationOfStringLiteralByte(const StringLiteral *SL, 44 unsigned ByteNo) const { 45 assert(!SL->isWide() && "This doesn't work for wide strings yet"); 46 47 // Loop over all of the tokens in this string until we find the one that 48 // contains the byte we're looking for. 49 unsigned TokNo = 0; 50 while (1) { 51 assert(TokNo < SL->getNumConcatenated() && "Invalid byte number!"); 52 SourceLocation StrTokLoc = SL->getStrTokenLoc(TokNo); 53 54 // Get the spelling of the string so that we can get the data that makes up 55 // the string literal, not the identifier for the macro it is potentially 56 // expanded through. 57 SourceLocation StrTokSpellingLoc = SourceMgr.getSpellingLoc(StrTokLoc); 58 59 // Re-lex the token to get its length and original spelling. 60 std::pair<FileID, unsigned> LocInfo = 61 SourceMgr.getDecomposedLoc(StrTokSpellingLoc); 62 bool Invalid = false; 63 llvm::StringRef Buffer = SourceMgr.getBufferData(LocInfo.first, &Invalid); 64 if (Invalid) 65 return StrTokSpellingLoc; 66 67 const char *StrData = Buffer.data()+LocInfo.second; 68 69 // Create a langops struct and enable trigraphs. This is sufficient for 70 // relexing tokens. 71 LangOptions LangOpts; 72 LangOpts.Trigraphs = true; 73 74 // Create a lexer starting at the beginning of this token. 75 Lexer TheLexer(StrTokSpellingLoc, LangOpts, Buffer.begin(), StrData, 76 Buffer.end()); 77 Token TheTok; 78 TheLexer.LexFromRawLexer(TheTok); 79 80 // Use the StringLiteralParser to compute the length of the string in bytes. 81 StringLiteralParser SLP(&TheTok, 1, PP, /*Complain=*/false); 82 unsigned TokNumBytes = SLP.GetStringLength(); 83 84 // If the byte is in this token, return the location of the byte. 85 if (ByteNo < TokNumBytes || 86 (ByteNo == TokNumBytes && TokNo == SL->getNumConcatenated())) { 87 unsigned Offset = 88 StringLiteralParser::getOffsetOfStringByte(TheTok, ByteNo, PP, 89 /*Complain=*/false); 90 91 // Now that we know the offset of the token in the spelling, use the 92 // preprocessor to get the offset in the original source. 93 return PP.AdvanceToTokenCharacter(StrTokLoc, Offset); 94 } 95 96 // Move to the next string token. 97 ++TokNo; 98 ByteNo -= TokNumBytes; 99 } 100} 101 102/// CheckablePrintfAttr - does a function call have a "printf" attribute 103/// and arguments that merit checking? 104bool Sema::CheckablePrintfAttr(const FormatAttr *Format, CallExpr *TheCall) { 105 if (Format->getType() == "printf") return true; 106 if (Format->getType() == "printf0") { 107 // printf0 allows null "format" string; if so don't check format/args 108 unsigned format_idx = Format->getFormatIdx() - 1; 109 // Does the index refer to the implicit object argument? 110 if (isa<CXXMemberCallExpr>(TheCall)) { 111 if (format_idx == 0) 112 return false; 113 --format_idx; 114 } 115 if (format_idx < TheCall->getNumArgs()) { 116 Expr *Format = TheCall->getArg(format_idx)->IgnoreParenCasts(); 117 if (!Format->isNullPointerConstant(Context, 118 Expr::NPC_ValueDependentIsNull)) 119 return true; 120 } 121 } 122 return false; 123} 124 125Action::OwningExprResult 126Sema::CheckBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) { 127 OwningExprResult TheCallResult(Owned(TheCall)); 128 129 switch (BuiltinID) { 130 case Builtin::BI__builtin___CFStringMakeConstantString: 131 assert(TheCall->getNumArgs() == 1 && 132 "Wrong # arguments to builtin CFStringMakeConstantString"); 133 if (CheckObjCString(TheCall->getArg(0))) 134 return ExprError(); 135 break; 136 case Builtin::BI__builtin_stdarg_start: 137 case Builtin::BI__builtin_va_start: 138 if (SemaBuiltinVAStart(TheCall)) 139 return ExprError(); 140 break; 141 case Builtin::BI__builtin_isgreater: 142 case Builtin::BI__builtin_isgreaterequal: 143 case Builtin::BI__builtin_isless: 144 case Builtin::BI__builtin_islessequal: 145 case Builtin::BI__builtin_islessgreater: 146 case Builtin::BI__builtin_isunordered: 147 if (SemaBuiltinUnorderedCompare(TheCall)) 148 return ExprError(); 149 break; 150 case Builtin::BI__builtin_fpclassify: 151 if (SemaBuiltinFPClassification(TheCall, 6)) 152 return ExprError(); 153 break; 154 case Builtin::BI__builtin_isfinite: 155 case Builtin::BI__builtin_isinf: 156 case Builtin::BI__builtin_isinf_sign: 157 case Builtin::BI__builtin_isnan: 158 case Builtin::BI__builtin_isnormal: 159 if (SemaBuiltinFPClassification(TheCall, 1)) 160 return ExprError(); 161 break; 162 case Builtin::BI__builtin_return_address: 163 case Builtin::BI__builtin_frame_address: { 164 llvm::APSInt Result; 165 if (SemaBuiltinConstantArg(TheCall, 0, Result)) 166 return ExprError(); 167 break; 168 } 169 case Builtin::BI__builtin_eh_return_data_regno: { 170 llvm::APSInt Result; 171 if (SemaBuiltinConstantArg(TheCall, 0, Result)) 172 return ExprError(); 173 break; 174 } 175 case Builtin::BI__builtin_shufflevector: 176 return SemaBuiltinShuffleVector(TheCall); 177 // TheCall will be freed by the smart pointer here, but that's fine, since 178 // SemaBuiltinShuffleVector guts it, but then doesn't release it. 179 case Builtin::BI__builtin_prefetch: 180 if (SemaBuiltinPrefetch(TheCall)) 181 return ExprError(); 182 break; 183 case Builtin::BI__builtin_object_size: 184 if (SemaBuiltinObjectSize(TheCall)) 185 return ExprError(); 186 break; 187 case Builtin::BI__builtin_longjmp: 188 if (SemaBuiltinLongjmp(TheCall)) 189 return ExprError(); 190 break; 191 case Builtin::BI__sync_fetch_and_add: 192 case Builtin::BI__sync_fetch_and_sub: 193 case Builtin::BI__sync_fetch_and_or: 194 case Builtin::BI__sync_fetch_and_and: 195 case Builtin::BI__sync_fetch_and_xor: 196 case Builtin::BI__sync_add_and_fetch: 197 case Builtin::BI__sync_sub_and_fetch: 198 case Builtin::BI__sync_and_and_fetch: 199 case Builtin::BI__sync_or_and_fetch: 200 case Builtin::BI__sync_xor_and_fetch: 201 case Builtin::BI__sync_val_compare_and_swap: 202 case Builtin::BI__sync_bool_compare_and_swap: 203 case Builtin::BI__sync_lock_test_and_set: 204 case Builtin::BI__sync_lock_release: 205 return SemaBuiltinAtomicOverloaded(move(TheCallResult)); 206 } 207 208 // Since the target specific builtins for each arch overlap, only check those 209 // of the arch we are compiling for. 210 if (BuiltinID >= Builtin::FirstTSBuiltin) { 211 switch (Context.Target.getTriple().getArch()) { 212 case llvm::Triple::arm: 213 case llvm::Triple::thumb: 214 if (CheckARMBuiltinFunctionCall(BuiltinID, TheCall)) 215 return ExprError(); 216 break; 217 case llvm::Triple::x86: 218 case llvm::Triple::x86_64: 219 if (CheckX86BuiltinFunctionCall(BuiltinID, TheCall)) 220 return ExprError(); 221 break; 222 default: 223 break; 224 } 225 } 226 227 return move(TheCallResult); 228} 229 230bool Sema::CheckX86BuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) { 231 switch (BuiltinID) { 232 case X86::BI__builtin_ia32_palignr128: 233 case X86::BI__builtin_ia32_palignr: { 234 llvm::APSInt Result; 235 if (SemaBuiltinConstantArg(TheCall, 2, Result)) 236 return true; 237 break; 238 } 239 } 240 return false; 241} 242 243// Get the valid immediate range for the specified NEON type code. 244static unsigned RFT(unsigned t, bool shift = false) { 245 bool quad = t & 0x10; 246 247 switch (t & 0x7) { 248 case 0: // i8 249 return shift ? 7 : (8 << (int)quad) - 1; 250 case 1: // i16 251 return shift ? 15 : (4 << (int)quad) - 1; 252 case 2: // i32 253 return shift ? 31 : (2 << (int)quad) - 1; 254 case 3: // i64 255 return shift ? 63 : (1 << (int)quad) - 1; 256 case 4: // f32 257 assert(!shift && "cannot shift float types!"); 258 return (2 << (int)quad) - 1; 259 case 5: // poly8 260 assert(!shift && "cannot shift polynomial types!"); 261 return (8 << (int)quad) - 1; 262 case 6: // poly16 263 assert(!shift && "cannot shift polynomial types!"); 264 return (4 << (int)quad) - 1; 265 case 7: // float16 266 assert(!shift && "cannot shift float types!"); 267 return (4 << (int)quad) - 1; 268 } 269 return 0; 270} 271 272bool Sema::CheckARMBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) { 273 llvm::APSInt Result; 274 275 unsigned mask = 0; 276 unsigned TV = 0; 277 switch (BuiltinID) { 278#define GET_NEON_OVERLOAD_CHECK 279#include "clang/Basic/arm_neon.inc" 280#undef GET_NEON_OVERLOAD_CHECK 281 } 282 283 // For NEON intrinsics which are overloaded on vector element type, validate 284 // the immediate which specifies which variant to emit. 285 if (mask) { 286 unsigned ArgNo = TheCall->getNumArgs()-1; 287 if (SemaBuiltinConstantArg(TheCall, ArgNo, Result)) 288 return true; 289 290 TV = Result.getLimitedValue(32); 291 if ((TV > 31) || (mask & (1 << TV)) == 0) 292 return Diag(TheCall->getLocStart(), diag::err_invalid_neon_type_code) 293 << TheCall->getArg(ArgNo)->getSourceRange(); 294 } 295 296 // For NEON intrinsics which take an immediate value as part of the 297 // instruction, range check them here. 298 unsigned i = 0, l = 0, u = 0; 299 switch (BuiltinID) { 300 default: return false; 301#define GET_NEON_IMMEDIATE_CHECK 302#include "clang/Basic/arm_neon.inc" 303#undef GET_NEON_IMMEDIATE_CHECK 304 }; 305 306 // Check that the immediate argument is actually a constant. 307 if (SemaBuiltinConstantArg(TheCall, i, Result)) 308 return true; 309 310 // Range check against the upper/lower values for this isntruction. 311 unsigned Val = Result.getZExtValue(); 312 if (Val < l || Val > (u + l)) 313 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 314 << llvm::utostr(l) << llvm::utostr(u+l) 315 << TheCall->getArg(i)->getSourceRange(); 316 317 return false; 318} 319 320/// CheckFunctionCall - Check a direct function call for various correctness 321/// and safety properties not strictly enforced by the C type system. 322bool Sema::CheckFunctionCall(FunctionDecl *FDecl, CallExpr *TheCall) { 323 // Get the IdentifierInfo* for the called function. 324 IdentifierInfo *FnInfo = FDecl->getIdentifier(); 325 326 // None of the checks below are needed for functions that don't have 327 // simple names (e.g., C++ conversion functions). 328 if (!FnInfo) 329 return false; 330 331 // FIXME: This mechanism should be abstracted to be less fragile and 332 // more efficient. For example, just map function ids to custom 333 // handlers. 334 335 // Printf checking. 336 if (const FormatAttr *Format = FDecl->getAttr<FormatAttr>()) { 337 const bool b = Format->getType() == "scanf"; 338 if (b || CheckablePrintfAttr(Format, TheCall)) { 339 bool HasVAListArg = Format->getFirstArg() == 0; 340 CheckPrintfScanfArguments(TheCall, HasVAListArg, 341 Format->getFormatIdx() - 1, 342 HasVAListArg ? 0 : Format->getFirstArg() - 1, 343 !b); 344 } 345 } 346 347 for (const NonNullAttr *NonNull = FDecl->getAttr<NonNullAttr>(); NonNull; 348 NonNull = NonNull->getNext<NonNullAttr>()) 349 CheckNonNullArguments(NonNull, TheCall); 350 351 return false; 352} 353 354bool Sema::CheckBlockCall(NamedDecl *NDecl, CallExpr *TheCall) { 355 // Printf checking. 356 const FormatAttr *Format = NDecl->getAttr<FormatAttr>(); 357 if (!Format) 358 return false; 359 360 const VarDecl *V = dyn_cast<VarDecl>(NDecl); 361 if (!V) 362 return false; 363 364 QualType Ty = V->getType(); 365 if (!Ty->isBlockPointerType()) 366 return false; 367 368 const bool b = Format->getType() == "scanf"; 369 if (!b && !CheckablePrintfAttr(Format, TheCall)) 370 return false; 371 372 bool HasVAListArg = Format->getFirstArg() == 0; 373 CheckPrintfScanfArguments(TheCall, HasVAListArg, Format->getFormatIdx() - 1, 374 HasVAListArg ? 0 : Format->getFirstArg() - 1, !b); 375 376 return false; 377} 378 379/// SemaBuiltinAtomicOverloaded - We have a call to a function like 380/// __sync_fetch_and_add, which is an overloaded function based on the pointer 381/// type of its first argument. The main ActOnCallExpr routines have already 382/// promoted the types of arguments because all of these calls are prototyped as 383/// void(...). 384/// 385/// This function goes through and does final semantic checking for these 386/// builtins, 387Sema::OwningExprResult 388Sema::SemaBuiltinAtomicOverloaded(OwningExprResult TheCallResult) { 389 CallExpr *TheCall = (CallExpr *)TheCallResult.get(); 390 DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts()); 391 FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl()); 392 393 // Ensure that we have at least one argument to do type inference from. 394 if (TheCall->getNumArgs() < 1) { 395 Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args_at_least) 396 << 0 << 1 << TheCall->getNumArgs() 397 << TheCall->getCallee()->getSourceRange(); 398 return ExprError(); 399 } 400 401 // Inspect the first argument of the atomic builtin. This should always be 402 // a pointer type, whose element is an integral scalar or pointer type. 403 // Because it is a pointer type, we don't have to worry about any implicit 404 // casts here. 405 // FIXME: We don't allow floating point scalars as input. 406 Expr *FirstArg = TheCall->getArg(0); 407 if (!FirstArg->getType()->isPointerType()) { 408 Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer) 409 << FirstArg->getType() << FirstArg->getSourceRange(); 410 return ExprError(); 411 } 412 413 QualType ValType = 414 FirstArg->getType()->getAs<PointerType>()->getPointeeType(); 415 if (!ValType->isIntegerType() && !ValType->isPointerType() && 416 !ValType->isBlockPointerType()) { 417 Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer_intptr) 418 << FirstArg->getType() << FirstArg->getSourceRange(); 419 return ExprError(); 420 } 421 422 // We need to figure out which concrete builtin this maps onto. For example, 423 // __sync_fetch_and_add with a 2 byte object turns into 424 // __sync_fetch_and_add_2. 425#define BUILTIN_ROW(x) \ 426 { Builtin::BI##x##_1, Builtin::BI##x##_2, Builtin::BI##x##_4, \ 427 Builtin::BI##x##_8, Builtin::BI##x##_16 } 428 429 static const unsigned BuiltinIndices[][5] = { 430 BUILTIN_ROW(__sync_fetch_and_add), 431 BUILTIN_ROW(__sync_fetch_and_sub), 432 BUILTIN_ROW(__sync_fetch_and_or), 433 BUILTIN_ROW(__sync_fetch_and_and), 434 BUILTIN_ROW(__sync_fetch_and_xor), 435 436 BUILTIN_ROW(__sync_add_and_fetch), 437 BUILTIN_ROW(__sync_sub_and_fetch), 438 BUILTIN_ROW(__sync_and_and_fetch), 439 BUILTIN_ROW(__sync_or_and_fetch), 440 BUILTIN_ROW(__sync_xor_and_fetch), 441 442 BUILTIN_ROW(__sync_val_compare_and_swap), 443 BUILTIN_ROW(__sync_bool_compare_and_swap), 444 BUILTIN_ROW(__sync_lock_test_and_set), 445 BUILTIN_ROW(__sync_lock_release) 446 }; 447#undef BUILTIN_ROW 448 449 // Determine the index of the size. 450 unsigned SizeIndex; 451 switch (Context.getTypeSizeInChars(ValType).getQuantity()) { 452 case 1: SizeIndex = 0; break; 453 case 2: SizeIndex = 1; break; 454 case 4: SizeIndex = 2; break; 455 case 8: SizeIndex = 3; break; 456 case 16: SizeIndex = 4; break; 457 default: 458 Diag(DRE->getLocStart(), diag::err_atomic_builtin_pointer_size) 459 << FirstArg->getType() << FirstArg->getSourceRange(); 460 return ExprError(); 461 } 462 463 // Each of these builtins has one pointer argument, followed by some number of 464 // values (0, 1 or 2) followed by a potentially empty varags list of stuff 465 // that we ignore. Find out which row of BuiltinIndices to read from as well 466 // as the number of fixed args. 467 unsigned BuiltinID = FDecl->getBuiltinID(); 468 unsigned BuiltinIndex, NumFixed = 1; 469 switch (BuiltinID) { 470 default: assert(0 && "Unknown overloaded atomic builtin!"); 471 case Builtin::BI__sync_fetch_and_add: BuiltinIndex = 0; break; 472 case Builtin::BI__sync_fetch_and_sub: BuiltinIndex = 1; break; 473 case Builtin::BI__sync_fetch_and_or: BuiltinIndex = 2; break; 474 case Builtin::BI__sync_fetch_and_and: BuiltinIndex = 3; break; 475 case Builtin::BI__sync_fetch_and_xor: BuiltinIndex = 4; break; 476 477 case Builtin::BI__sync_add_and_fetch: BuiltinIndex = 5; break; 478 case Builtin::BI__sync_sub_and_fetch: BuiltinIndex = 6; break; 479 case Builtin::BI__sync_and_and_fetch: BuiltinIndex = 7; break; 480 case Builtin::BI__sync_or_and_fetch: BuiltinIndex = 8; break; 481 case Builtin::BI__sync_xor_and_fetch: BuiltinIndex = 9; break; 482 483 case Builtin::BI__sync_val_compare_and_swap: 484 BuiltinIndex = 10; 485 NumFixed = 2; 486 break; 487 case Builtin::BI__sync_bool_compare_and_swap: 488 BuiltinIndex = 11; 489 NumFixed = 2; 490 break; 491 case Builtin::BI__sync_lock_test_and_set: BuiltinIndex = 12; break; 492 case Builtin::BI__sync_lock_release: 493 BuiltinIndex = 13; 494 NumFixed = 0; 495 break; 496 } 497 498 // Now that we know how many fixed arguments we expect, first check that we 499 // have at least that many. 500 if (TheCall->getNumArgs() < 1+NumFixed) { 501 Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args_at_least) 502 << 0 << 1+NumFixed << TheCall->getNumArgs() 503 << TheCall->getCallee()->getSourceRange(); 504 return ExprError(); 505 } 506 507 // Get the decl for the concrete builtin from this, we can tell what the 508 // concrete integer type we should convert to is. 509 unsigned NewBuiltinID = BuiltinIndices[BuiltinIndex][SizeIndex]; 510 const char *NewBuiltinName = Context.BuiltinInfo.GetName(NewBuiltinID); 511 IdentifierInfo *NewBuiltinII = PP.getIdentifierInfo(NewBuiltinName); 512 FunctionDecl *NewBuiltinDecl = 513 cast<FunctionDecl>(LazilyCreateBuiltin(NewBuiltinII, NewBuiltinID, 514 TUScope, false, DRE->getLocStart())); 515 const FunctionProtoType *BuiltinFT = 516 NewBuiltinDecl->getType()->getAs<FunctionProtoType>(); 517 518 QualType OrigValType = ValType; 519 ValType = BuiltinFT->getArgType(0)->getAs<PointerType>()->getPointeeType(); 520 521 // If the first type needs to be converted (e.g. void** -> int*), do it now. 522 if (BuiltinFT->getArgType(0) != FirstArg->getType()) { 523 ImpCastExprToType(FirstArg, BuiltinFT->getArgType(0), CastExpr::CK_BitCast); 524 TheCall->setArg(0, FirstArg); 525 } 526 527 // Next, walk the valid ones promoting to the right type. 528 for (unsigned i = 0; i != NumFixed; ++i) { 529 Expr *Arg = TheCall->getArg(i+1); 530 531 // If the argument is an implicit cast, then there was a promotion due to 532 // "...", just remove it now. 533 if (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Arg)) { 534 Arg = ICE->getSubExpr(); 535 ICE->setSubExpr(0); 536 ICE->Destroy(Context); 537 TheCall->setArg(i+1, Arg); 538 } 539 540 // GCC does an implicit conversion to the pointer or integer ValType. This 541 // can fail in some cases (1i -> int**), check for this error case now. 542 CastExpr::CastKind Kind = CastExpr::CK_Unknown; 543 CXXBaseSpecifierArray BasePath; 544 if (CheckCastTypes(Arg->getSourceRange(), ValType, Arg, Kind, BasePath)) 545 return ExprError(); 546 547 // Okay, we have something that *can* be converted to the right type. Check 548 // to see if there is a potentially weird extension going on here. This can 549 // happen when you do an atomic operation on something like an char* and 550 // pass in 42. The 42 gets converted to char. This is even more strange 551 // for things like 45.123 -> char, etc. 552 // FIXME: Do this check. 553 ImpCastExprToType(Arg, ValType, Kind); 554 TheCall->setArg(i+1, Arg); 555 } 556 557 // Switch the DeclRefExpr to refer to the new decl. 558 DRE->setDecl(NewBuiltinDecl); 559 DRE->setType(NewBuiltinDecl->getType()); 560 561 // Set the callee in the CallExpr. 562 // FIXME: This leaks the original parens and implicit casts. 563 Expr *PromotedCall = DRE; 564 UsualUnaryConversions(PromotedCall); 565 TheCall->setCallee(PromotedCall); 566 567 // Change the result type of the call to match the result type of the decl. 568 TheCall->setType(NewBuiltinDecl->getCallResultType()); 569 570 // If the value type was converted to an integer when processing the 571 // arguments (e.g. void* -> int), we need to convert the result back. 572 if (!Context.hasSameUnqualifiedType(ValType, OrigValType)) { 573 Expr *E = TheCallResult.takeAs<Expr>(); 574 575 assert(ValType->isIntegerType() && 576 "We always convert atomic operation values to integers."); 577 // FIXME: Handle floating point value type here too. 578 CastExpr::CastKind Kind; 579 if (OrigValType->isIntegerType()) 580 Kind = CastExpr::CK_IntegralCast; 581 else if (OrigValType->hasPointerRepresentation()) 582 Kind = CastExpr::CK_IntegralToPointer; 583 else 584 llvm_unreachable("Unhandled original value type!"); 585 586 ImpCastExprToType(E, OrigValType, Kind); 587 return Owned(E); 588 } 589 590 return move(TheCallResult); 591} 592 593 594/// CheckObjCString - Checks that the argument to the builtin 595/// CFString constructor is correct 596/// FIXME: GCC currently emits the following warning: 597/// "warning: input conversion stopped due to an input byte that does not 598/// belong to the input codeset UTF-8" 599/// Note: It might also make sense to do the UTF-16 conversion here (would 600/// simplify the backend). 601bool Sema::CheckObjCString(Expr *Arg) { 602 Arg = Arg->IgnoreParenCasts(); 603 StringLiteral *Literal = dyn_cast<StringLiteral>(Arg); 604 605 if (!Literal || Literal->isWide()) { 606 Diag(Arg->getLocStart(), diag::err_cfstring_literal_not_string_constant) 607 << Arg->getSourceRange(); 608 return true; 609 } 610 611 const char *Data = Literal->getStrData(); 612 unsigned Length = Literal->getByteLength(); 613 614 for (unsigned i = 0; i < Length; ++i) { 615 if (!Data[i]) { 616 Diag(getLocationOfStringLiteralByte(Literal, i), 617 diag::warn_cfstring_literal_contains_nul_character) 618 << Arg->getSourceRange(); 619 break; 620 } 621 } 622 623 return false; 624} 625 626/// SemaBuiltinVAStart - Check the arguments to __builtin_va_start for validity. 627/// Emit an error and return true on failure, return false on success. 628bool Sema::SemaBuiltinVAStart(CallExpr *TheCall) { 629 Expr *Fn = TheCall->getCallee(); 630 if (TheCall->getNumArgs() > 2) { 631 Diag(TheCall->getArg(2)->getLocStart(), 632 diag::err_typecheck_call_too_many_args) 633 << 0 /*function call*/ << 2 << TheCall->getNumArgs() 634 << Fn->getSourceRange() 635 << SourceRange(TheCall->getArg(2)->getLocStart(), 636 (*(TheCall->arg_end()-1))->getLocEnd()); 637 return true; 638 } 639 640 if (TheCall->getNumArgs() < 2) { 641 return Diag(TheCall->getLocEnd(), 642 diag::err_typecheck_call_too_few_args_at_least) 643 << 0 /*function call*/ << 2 << TheCall->getNumArgs(); 644 } 645 646 // Determine whether the current function is variadic or not. 647 BlockScopeInfo *CurBlock = getCurBlock(); 648 bool isVariadic; 649 if (CurBlock) 650 isVariadic = CurBlock->TheDecl->isVariadic(); 651 else if (FunctionDecl *FD = getCurFunctionDecl()) 652 isVariadic = FD->isVariadic(); 653 else 654 isVariadic = getCurMethodDecl()->isVariadic(); 655 656 if (!isVariadic) { 657 Diag(Fn->getLocStart(), diag::err_va_start_used_in_non_variadic_function); 658 return true; 659 } 660 661 // Verify that the second argument to the builtin is the last argument of the 662 // current function or method. 663 bool SecondArgIsLastNamedArgument = false; 664 const Expr *Arg = TheCall->getArg(1)->IgnoreParenCasts(); 665 666 if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Arg)) { 667 if (const ParmVarDecl *PV = dyn_cast<ParmVarDecl>(DR->getDecl())) { 668 // FIXME: This isn't correct for methods (results in bogus warning). 669 // Get the last formal in the current function. 670 const ParmVarDecl *LastArg; 671 if (CurBlock) 672 LastArg = *(CurBlock->TheDecl->param_end()-1); 673 else if (FunctionDecl *FD = getCurFunctionDecl()) 674 LastArg = *(FD->param_end()-1); 675 else 676 LastArg = *(getCurMethodDecl()->param_end()-1); 677 SecondArgIsLastNamedArgument = PV == LastArg; 678 } 679 } 680 681 if (!SecondArgIsLastNamedArgument) 682 Diag(TheCall->getArg(1)->getLocStart(), 683 diag::warn_second_parameter_of_va_start_not_last_named_argument); 684 return false; 685} 686 687/// SemaBuiltinUnorderedCompare - Handle functions like __builtin_isgreater and 688/// friends. This is declared to take (...), so we have to check everything. 689bool Sema::SemaBuiltinUnorderedCompare(CallExpr *TheCall) { 690 if (TheCall->getNumArgs() < 2) 691 return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args) 692 << 0 << 2 << TheCall->getNumArgs()/*function call*/; 693 if (TheCall->getNumArgs() > 2) 694 return Diag(TheCall->getArg(2)->getLocStart(), 695 diag::err_typecheck_call_too_many_args) 696 << 0 /*function call*/ << 2 << TheCall->getNumArgs() 697 << SourceRange(TheCall->getArg(2)->getLocStart(), 698 (*(TheCall->arg_end()-1))->getLocEnd()); 699 700 Expr *OrigArg0 = TheCall->getArg(0); 701 Expr *OrigArg1 = TheCall->getArg(1); 702 703 // Do standard promotions between the two arguments, returning their common 704 // type. 705 QualType Res = UsualArithmeticConversions(OrigArg0, OrigArg1, false); 706 707 // Make sure any conversions are pushed back into the call; this is 708 // type safe since unordered compare builtins are declared as "_Bool 709 // foo(...)". 710 TheCall->setArg(0, OrigArg0); 711 TheCall->setArg(1, OrigArg1); 712 713 if (OrigArg0->isTypeDependent() || OrigArg1->isTypeDependent()) 714 return false; 715 716 // If the common type isn't a real floating type, then the arguments were 717 // invalid for this operation. 718 if (!Res->isRealFloatingType()) 719 return Diag(OrigArg0->getLocStart(), 720 diag::err_typecheck_call_invalid_ordered_compare) 721 << OrigArg0->getType() << OrigArg1->getType() 722 << SourceRange(OrigArg0->getLocStart(), OrigArg1->getLocEnd()); 723 724 return false; 725} 726 727/// SemaBuiltinSemaBuiltinFPClassification - Handle functions like 728/// __builtin_isnan and friends. This is declared to take (...), so we have 729/// to check everything. We expect the last argument to be a floating point 730/// value. 731bool Sema::SemaBuiltinFPClassification(CallExpr *TheCall, unsigned NumArgs) { 732 if (TheCall->getNumArgs() < NumArgs) 733 return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args) 734 << 0 << NumArgs << TheCall->getNumArgs()/*function call*/; 735 if (TheCall->getNumArgs() > NumArgs) 736 return Diag(TheCall->getArg(NumArgs)->getLocStart(), 737 diag::err_typecheck_call_too_many_args) 738 << 0 /*function call*/ << NumArgs << TheCall->getNumArgs() 739 << SourceRange(TheCall->getArg(NumArgs)->getLocStart(), 740 (*(TheCall->arg_end()-1))->getLocEnd()); 741 742 Expr *OrigArg = TheCall->getArg(NumArgs-1); 743 744 if (OrigArg->isTypeDependent()) 745 return false; 746 747 // This operation requires a non-_Complex floating-point number. 748 if (!OrigArg->getType()->isRealFloatingType()) 749 return Diag(OrigArg->getLocStart(), 750 diag::err_typecheck_call_invalid_unary_fp) 751 << OrigArg->getType() << OrigArg->getSourceRange(); 752 753 // If this is an implicit conversion from float -> double, remove it. 754 if (ImplicitCastExpr *Cast = dyn_cast<ImplicitCastExpr>(OrigArg)) { 755 Expr *CastArg = Cast->getSubExpr(); 756 if (CastArg->getType()->isSpecificBuiltinType(BuiltinType::Float)) { 757 assert(Cast->getType()->isSpecificBuiltinType(BuiltinType::Double) && 758 "promotion from float to double is the only expected cast here"); 759 Cast->setSubExpr(0); 760 Cast->Destroy(Context); 761 TheCall->setArg(NumArgs-1, CastArg); 762 OrigArg = CastArg; 763 } 764 } 765 766 return false; 767} 768 769/// SemaBuiltinShuffleVector - Handle __builtin_shufflevector. 770// This is declared to take (...), so we have to check everything. 771Action::OwningExprResult Sema::SemaBuiltinShuffleVector(CallExpr *TheCall) { 772 if (TheCall->getNumArgs() < 2) 773 return ExprError(Diag(TheCall->getLocEnd(), 774 diag::err_typecheck_call_too_few_args_at_least) 775 << 0 /*function call*/ << 2 << TheCall->getNumArgs() 776 << TheCall->getSourceRange()); 777 778 // Determine which of the following types of shufflevector we're checking: 779 // 1) unary, vector mask: (lhs, mask) 780 // 2) binary, vector mask: (lhs, rhs, mask) 781 // 3) binary, scalar mask: (lhs, rhs, index, ..., index) 782 QualType resType = TheCall->getArg(0)->getType(); 783 unsigned numElements = 0; 784 785 if (!TheCall->getArg(0)->isTypeDependent() && 786 !TheCall->getArg(1)->isTypeDependent()) { 787 QualType LHSType = TheCall->getArg(0)->getType(); 788 QualType RHSType = TheCall->getArg(1)->getType(); 789 790 if (!LHSType->isVectorType() || !RHSType->isVectorType()) { 791 Diag(TheCall->getLocStart(), diag::err_shufflevector_non_vector) 792 << SourceRange(TheCall->getArg(0)->getLocStart(), 793 TheCall->getArg(1)->getLocEnd()); 794 return ExprError(); 795 } 796 797 numElements = LHSType->getAs<VectorType>()->getNumElements(); 798 unsigned numResElements = TheCall->getNumArgs() - 2; 799 800 // Check to see if we have a call with 2 vector arguments, the unary shuffle 801 // with mask. If so, verify that RHS is an integer vector type with the 802 // same number of elts as lhs. 803 if (TheCall->getNumArgs() == 2) { 804 if (!RHSType->isIntegerType() || 805 RHSType->getAs<VectorType>()->getNumElements() != numElements) 806 Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector) 807 << SourceRange(TheCall->getArg(1)->getLocStart(), 808 TheCall->getArg(1)->getLocEnd()); 809 numResElements = numElements; 810 } 811 else if (!Context.hasSameUnqualifiedType(LHSType, RHSType)) { 812 Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector) 813 << SourceRange(TheCall->getArg(0)->getLocStart(), 814 TheCall->getArg(1)->getLocEnd()); 815 return ExprError(); 816 } else if (numElements != numResElements) { 817 QualType eltType = LHSType->getAs<VectorType>()->getElementType(); 818 resType = Context.getVectorType(eltType, numResElements, 819 VectorType::NotAltiVec); 820 } 821 } 822 823 for (unsigned i = 2; i < TheCall->getNumArgs(); i++) { 824 if (TheCall->getArg(i)->isTypeDependent() || 825 TheCall->getArg(i)->isValueDependent()) 826 continue; 827 828 llvm::APSInt Result(32); 829 if (!TheCall->getArg(i)->isIntegerConstantExpr(Result, Context)) 830 return ExprError(Diag(TheCall->getLocStart(), 831 diag::err_shufflevector_nonconstant_argument) 832 << TheCall->getArg(i)->getSourceRange()); 833 834 if (Result.getActiveBits() > 64 || Result.getZExtValue() >= numElements*2) 835 return ExprError(Diag(TheCall->getLocStart(), 836 diag::err_shufflevector_argument_too_large) 837 << TheCall->getArg(i)->getSourceRange()); 838 } 839 840 llvm::SmallVector<Expr*, 32> exprs; 841 842 for (unsigned i = 0, e = TheCall->getNumArgs(); i != e; i++) { 843 exprs.push_back(TheCall->getArg(i)); 844 TheCall->setArg(i, 0); 845 } 846 847 return Owned(new (Context) ShuffleVectorExpr(Context, exprs.begin(), 848 exprs.size(), resType, 849 TheCall->getCallee()->getLocStart(), 850 TheCall->getRParenLoc())); 851} 852 853/// SemaBuiltinPrefetch - Handle __builtin_prefetch. 854// This is declared to take (const void*, ...) and can take two 855// optional constant int args. 856bool Sema::SemaBuiltinPrefetch(CallExpr *TheCall) { 857 unsigned NumArgs = TheCall->getNumArgs(); 858 859 if (NumArgs > 3) 860 return Diag(TheCall->getLocEnd(), 861 diag::err_typecheck_call_too_many_args_at_most) 862 << 0 /*function call*/ << 3 << NumArgs 863 << TheCall->getSourceRange(); 864 865 // Argument 0 is checked for us and the remaining arguments must be 866 // constant integers. 867 for (unsigned i = 1; i != NumArgs; ++i) { 868 Expr *Arg = TheCall->getArg(i); 869 870 llvm::APSInt Result; 871 if (SemaBuiltinConstantArg(TheCall, i, Result)) 872 return true; 873 874 // FIXME: gcc issues a warning and rewrites these to 0. These 875 // seems especially odd for the third argument since the default 876 // is 3. 877 if (i == 1) { 878 if (Result.getLimitedValue() > 1) 879 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 880 << "0" << "1" << Arg->getSourceRange(); 881 } else { 882 if (Result.getLimitedValue() > 3) 883 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 884 << "0" << "3" << Arg->getSourceRange(); 885 } 886 } 887 888 return false; 889} 890 891/// SemaBuiltinConstantArg - Handle a check if argument ArgNum of CallExpr 892/// TheCall is a constant expression. 893bool Sema::SemaBuiltinConstantArg(CallExpr *TheCall, int ArgNum, 894 llvm::APSInt &Result) { 895 Expr *Arg = TheCall->getArg(ArgNum); 896 DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts()); 897 FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl()); 898 899 if (Arg->isTypeDependent() || Arg->isValueDependent()) return false; 900 901 if (!Arg->isIntegerConstantExpr(Result, Context)) 902 return Diag(TheCall->getLocStart(), diag::err_constant_integer_arg_type) 903 << FDecl->getDeclName() << Arg->getSourceRange(); 904 905 return false; 906} 907 908/// SemaBuiltinObjectSize - Handle __builtin_object_size(void *ptr, 909/// int type). This simply type checks that type is one of the defined 910/// constants (0-3). 911// For compatability check 0-3, llvm only handles 0 and 2. 912bool Sema::SemaBuiltinObjectSize(CallExpr *TheCall) { 913 llvm::APSInt Result; 914 915 // Check constant-ness first. 916 if (SemaBuiltinConstantArg(TheCall, 1, Result)) 917 return true; 918 919 Expr *Arg = TheCall->getArg(1); 920 if (Result.getSExtValue() < 0 || Result.getSExtValue() > 3) { 921 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 922 << "0" << "3" << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); 923 } 924 925 return false; 926} 927 928/// SemaBuiltinLongjmp - Handle __builtin_longjmp(void *env[5], int val). 929/// This checks that val is a constant 1. 930bool Sema::SemaBuiltinLongjmp(CallExpr *TheCall) { 931 Expr *Arg = TheCall->getArg(1); 932 llvm::APSInt Result; 933 934 // TODO: This is less than ideal. Overload this to take a value. 935 if (SemaBuiltinConstantArg(TheCall, 1, Result)) 936 return true; 937 938 if (Result != 1) 939 return Diag(TheCall->getLocStart(), diag::err_builtin_longjmp_invalid_val) 940 << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); 941 942 return false; 943} 944 945// Handle i > 1 ? "x" : "y", recursivelly 946bool Sema::SemaCheckStringLiteral(const Expr *E, const CallExpr *TheCall, 947 bool HasVAListArg, 948 unsigned format_idx, unsigned firstDataArg, 949 bool isPrintf) { 950 951 if (E->isTypeDependent() || E->isValueDependent()) 952 return false; 953 954 switch (E->getStmtClass()) { 955 case Stmt::ConditionalOperatorClass: { 956 const ConditionalOperator *C = cast<ConditionalOperator>(E); 957 return SemaCheckStringLiteral(C->getTrueExpr(), TheCall, HasVAListArg, 958 format_idx, firstDataArg, isPrintf) 959 && SemaCheckStringLiteral(C->getRHS(), TheCall, HasVAListArg, 960 format_idx, firstDataArg, isPrintf); 961 } 962 963 case Stmt::ImplicitCastExprClass: { 964 const ImplicitCastExpr *Expr = cast<ImplicitCastExpr>(E); 965 return SemaCheckStringLiteral(Expr->getSubExpr(), TheCall, HasVAListArg, 966 format_idx, firstDataArg, isPrintf); 967 } 968 969 case Stmt::ParenExprClass: { 970 const ParenExpr *Expr = cast<ParenExpr>(E); 971 return SemaCheckStringLiteral(Expr->getSubExpr(), TheCall, HasVAListArg, 972 format_idx, firstDataArg, isPrintf); 973 } 974 975 case Stmt::DeclRefExprClass: { 976 const DeclRefExpr *DR = cast<DeclRefExpr>(E); 977 978 // As an exception, do not flag errors for variables binding to 979 // const string literals. 980 if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) { 981 bool isConstant = false; 982 QualType T = DR->getType(); 983 984 if (const ArrayType *AT = Context.getAsArrayType(T)) { 985 isConstant = AT->getElementType().isConstant(Context); 986 } else if (const PointerType *PT = T->getAs<PointerType>()) { 987 isConstant = T.isConstant(Context) && 988 PT->getPointeeType().isConstant(Context); 989 } 990 991 if (isConstant) { 992 if (const Expr *Init = VD->getAnyInitializer()) 993 return SemaCheckStringLiteral(Init, TheCall, 994 HasVAListArg, format_idx, firstDataArg, 995 isPrintf); 996 } 997 998 // For vprintf* functions (i.e., HasVAListArg==true), we add a 999 // special check to see if the format string is a function parameter 1000 // of the function calling the printf function. If the function 1001 // has an attribute indicating it is a printf-like function, then we 1002 // should suppress warnings concerning non-literals being used in a call 1003 // to a vprintf function. For example: 1004 // 1005 // void 1006 // logmessage(char const *fmt __attribute__ (format (printf, 1, 2)), ...){ 1007 // va_list ap; 1008 // va_start(ap, fmt); 1009 // vprintf(fmt, ap); // Do NOT emit a warning about "fmt". 1010 // ... 1011 // 1012 // 1013 // FIXME: We don't have full attribute support yet, so just check to see 1014 // if the argument is a DeclRefExpr that references a parameter. We'll 1015 // add proper support for checking the attribute later. 1016 if (HasVAListArg) 1017 if (isa<ParmVarDecl>(VD)) 1018 return true; 1019 } 1020 1021 return false; 1022 } 1023 1024 case Stmt::CallExprClass: { 1025 const CallExpr *CE = cast<CallExpr>(E); 1026 if (const ImplicitCastExpr *ICE 1027 = dyn_cast<ImplicitCastExpr>(CE->getCallee())) { 1028 if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(ICE->getSubExpr())) { 1029 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(DRE->getDecl())) { 1030 if (const FormatArgAttr *FA = FD->getAttr<FormatArgAttr>()) { 1031 unsigned ArgIndex = FA->getFormatIdx(); 1032 const Expr *Arg = CE->getArg(ArgIndex - 1); 1033 1034 return SemaCheckStringLiteral(Arg, TheCall, HasVAListArg, 1035 format_idx, firstDataArg, isPrintf); 1036 } 1037 } 1038 } 1039 } 1040 1041 return false; 1042 } 1043 case Stmt::ObjCStringLiteralClass: 1044 case Stmt::StringLiteralClass: { 1045 const StringLiteral *StrE = NULL; 1046 1047 if (const ObjCStringLiteral *ObjCFExpr = dyn_cast<ObjCStringLiteral>(E)) 1048 StrE = ObjCFExpr->getString(); 1049 else 1050 StrE = cast<StringLiteral>(E); 1051 1052 if (StrE) { 1053 CheckFormatString(StrE, E, TheCall, HasVAListArg, format_idx, 1054 firstDataArg, isPrintf); 1055 return true; 1056 } 1057 1058 return false; 1059 } 1060 1061 default: 1062 return false; 1063 } 1064} 1065 1066void 1067Sema::CheckNonNullArguments(const NonNullAttr *NonNull, 1068 const CallExpr *TheCall) { 1069 for (NonNullAttr::iterator i = NonNull->begin(), e = NonNull->end(); 1070 i != e; ++i) { 1071 const Expr *ArgExpr = TheCall->getArg(*i); 1072 if (ArgExpr->isNullPointerConstant(Context, 1073 Expr::NPC_ValueDependentIsNotNull)) 1074 Diag(TheCall->getCallee()->getLocStart(), diag::warn_null_arg) 1075 << ArgExpr->getSourceRange(); 1076 } 1077} 1078 1079/// CheckPrintfScanfArguments - Check calls to printf and scanf (and similar 1080/// functions) for correct use of format strings. 1081void 1082Sema::CheckPrintfScanfArguments(const CallExpr *TheCall, bool HasVAListArg, 1083 unsigned format_idx, unsigned firstDataArg, 1084 bool isPrintf) { 1085 1086 const Expr *Fn = TheCall->getCallee(); 1087 1088 // The way the format attribute works in GCC, the implicit this argument 1089 // of member functions is counted. However, it doesn't appear in our own 1090 // lists, so decrement format_idx in that case. 1091 if (isa<CXXMemberCallExpr>(TheCall)) { 1092 // Catch a format attribute mistakenly referring to the object argument. 1093 if (format_idx == 0) 1094 return; 1095 --format_idx; 1096 if(firstDataArg != 0) 1097 --firstDataArg; 1098 } 1099 1100 // CHECK: printf/scanf-like function is called with no format string. 1101 if (format_idx >= TheCall->getNumArgs()) { 1102 Diag(TheCall->getRParenLoc(), diag::warn_missing_format_string) 1103 << Fn->getSourceRange(); 1104 return; 1105 } 1106 1107 const Expr *OrigFormatExpr = TheCall->getArg(format_idx)->IgnoreParenCasts(); 1108 1109 // CHECK: format string is not a string literal. 1110 // 1111 // Dynamically generated format strings are difficult to 1112 // automatically vet at compile time. Requiring that format strings 1113 // are string literals: (1) permits the checking of format strings by 1114 // the compiler and thereby (2) can practically remove the source of 1115 // many format string exploits. 1116 1117 // Format string can be either ObjC string (e.g. @"%d") or 1118 // C string (e.g. "%d") 1119 // ObjC string uses the same format specifiers as C string, so we can use 1120 // the same format string checking logic for both ObjC and C strings. 1121 if (SemaCheckStringLiteral(OrigFormatExpr, TheCall, HasVAListArg, format_idx, 1122 firstDataArg, isPrintf)) 1123 return; // Literal format string found, check done! 1124 1125 // If there are no arguments specified, warn with -Wformat-security, otherwise 1126 // warn only with -Wformat-nonliteral. 1127 if (TheCall->getNumArgs() == format_idx+1) 1128 Diag(TheCall->getArg(format_idx)->getLocStart(), 1129 diag::warn_format_nonliteral_noargs) 1130 << OrigFormatExpr->getSourceRange(); 1131 else 1132 Diag(TheCall->getArg(format_idx)->getLocStart(), 1133 diag::warn_format_nonliteral) 1134 << OrigFormatExpr->getSourceRange(); 1135} 1136 1137namespace { 1138class CheckFormatHandler : public analyze_format_string::FormatStringHandler { 1139protected: 1140 Sema &S; 1141 const StringLiteral *FExpr; 1142 const Expr *OrigFormatExpr; 1143 const unsigned FirstDataArg; 1144 const unsigned NumDataArgs; 1145 const bool IsObjCLiteral; 1146 const char *Beg; // Start of format string. 1147 const bool HasVAListArg; 1148 const CallExpr *TheCall; 1149 unsigned FormatIdx; 1150 llvm::BitVector CoveredArgs; 1151 bool usesPositionalArgs; 1152 bool atFirstArg; 1153public: 1154 CheckFormatHandler(Sema &s, const StringLiteral *fexpr, 1155 const Expr *origFormatExpr, unsigned firstDataArg, 1156 unsigned numDataArgs, bool isObjCLiteral, 1157 const char *beg, bool hasVAListArg, 1158 const CallExpr *theCall, unsigned formatIdx) 1159 : S(s), FExpr(fexpr), OrigFormatExpr(origFormatExpr), 1160 FirstDataArg(firstDataArg), 1161 NumDataArgs(numDataArgs), 1162 IsObjCLiteral(isObjCLiteral), Beg(beg), 1163 HasVAListArg(hasVAListArg), 1164 TheCall(theCall), FormatIdx(formatIdx), 1165 usesPositionalArgs(false), atFirstArg(true) { 1166 CoveredArgs.resize(numDataArgs); 1167 CoveredArgs.reset(); 1168 } 1169 1170 void DoneProcessing(); 1171 1172 void HandleIncompleteSpecifier(const char *startSpecifier, 1173 unsigned specifierLen); 1174 1175 virtual void HandleInvalidPosition(const char *startSpecifier, 1176 unsigned specifierLen, 1177 analyze_format_string::PositionContext p); 1178 1179 virtual void HandleZeroPosition(const char *startPos, unsigned posLen); 1180 1181 void HandleNullChar(const char *nullCharacter); 1182 1183protected: 1184 SourceRange getFormatStringRange(); 1185 CharSourceRange getSpecifierRange(const char *startSpecifier, 1186 unsigned specifierLen); 1187 SourceLocation getLocationOfByte(const char *x); 1188 1189 const Expr *getDataArg(unsigned i) const; 1190}; 1191} 1192 1193SourceRange CheckFormatHandler::getFormatStringRange() { 1194 return OrigFormatExpr->getSourceRange(); 1195} 1196 1197CharSourceRange CheckFormatHandler:: 1198getSpecifierRange(const char *startSpecifier, unsigned specifierLen) { 1199 SourceLocation Start = getLocationOfByte(startSpecifier); 1200 SourceLocation End = getLocationOfByte(startSpecifier + specifierLen - 1); 1201 1202 // Advance the end SourceLocation by one due to half-open ranges. 1203 End = End.getFileLocWithOffset(1); 1204 1205 return CharSourceRange::getCharRange(Start, End); 1206} 1207 1208SourceLocation CheckFormatHandler::getLocationOfByte(const char *x) { 1209 return S.getLocationOfStringLiteralByte(FExpr, x - Beg); 1210} 1211 1212void CheckFormatHandler::HandleIncompleteSpecifier(const char *startSpecifier, 1213 unsigned specifierLen){ 1214 SourceLocation Loc = getLocationOfByte(startSpecifier); 1215 S.Diag(Loc, diag::warn_printf_incomplete_specifier) 1216 << getSpecifierRange(startSpecifier, specifierLen); 1217} 1218 1219void 1220CheckFormatHandler::HandleInvalidPosition(const char *startPos, unsigned posLen, 1221 analyze_format_string::PositionContext p) { 1222 SourceLocation Loc = getLocationOfByte(startPos); 1223 S.Diag(Loc, diag::warn_format_invalid_positional_specifier) 1224 << (unsigned) p << getSpecifierRange(startPos, posLen); 1225} 1226 1227void CheckFormatHandler::HandleZeroPosition(const char *startPos, 1228 unsigned posLen) { 1229 SourceLocation Loc = getLocationOfByte(startPos); 1230 S.Diag(Loc, diag::warn_format_zero_positional_specifier) 1231 << getSpecifierRange(startPos, posLen); 1232} 1233 1234void CheckFormatHandler::HandleNullChar(const char *nullCharacter) { 1235 // The presence of a null character is likely an error. 1236 S.Diag(getLocationOfByte(nullCharacter), 1237 diag::warn_printf_format_string_contains_null_char) 1238 << getFormatStringRange(); 1239} 1240 1241const Expr *CheckFormatHandler::getDataArg(unsigned i) const { 1242 return TheCall->getArg(FirstDataArg + i); 1243} 1244 1245void CheckFormatHandler::DoneProcessing() { 1246 // Does the number of data arguments exceed the number of 1247 // format conversions in the format string? 1248 if (!HasVAListArg) { 1249 // Find any arguments that weren't covered. 1250 CoveredArgs.flip(); 1251 signed notCoveredArg = CoveredArgs.find_first(); 1252 if (notCoveredArg >= 0) { 1253 assert((unsigned)notCoveredArg < NumDataArgs); 1254 S.Diag(getDataArg((unsigned) notCoveredArg)->getLocStart(), 1255 diag::warn_printf_data_arg_not_used) 1256 << getFormatStringRange(); 1257 } 1258 } 1259} 1260 1261//===--- CHECK: Printf format string checking ------------------------------===// 1262 1263namespace { 1264class CheckPrintfHandler : public CheckFormatHandler { 1265public: 1266 CheckPrintfHandler(Sema &s, const StringLiteral *fexpr, 1267 const Expr *origFormatExpr, unsigned firstDataArg, 1268 unsigned numDataArgs, bool isObjCLiteral, 1269 const char *beg, bool hasVAListArg, 1270 const CallExpr *theCall, unsigned formatIdx) 1271 : CheckFormatHandler(s, fexpr, origFormatExpr, firstDataArg, 1272 numDataArgs, isObjCLiteral, beg, hasVAListArg, 1273 theCall, formatIdx) {} 1274 1275 1276 bool HandleInvalidPrintfConversionSpecifier( 1277 const analyze_printf::PrintfSpecifier &FS, 1278 const char *startSpecifier, 1279 unsigned specifierLen); 1280 1281 bool HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier &FS, 1282 const char *startSpecifier, 1283 unsigned specifierLen); 1284 1285 bool HandleAmount(const analyze_format_string::OptionalAmount &Amt, unsigned k, 1286 const char *startSpecifier, unsigned specifierLen); 1287 void HandleInvalidAmount(const analyze_printf::PrintfSpecifier &FS, 1288 const analyze_printf::OptionalAmount &Amt, 1289 unsigned type, 1290 const char *startSpecifier, unsigned specifierLen); 1291 void HandleFlag(const analyze_printf::PrintfSpecifier &FS, 1292 const analyze_printf::OptionalFlag &flag, 1293 const char *startSpecifier, unsigned specifierLen); 1294 void HandleIgnoredFlag(const analyze_printf::PrintfSpecifier &FS, 1295 const analyze_printf::OptionalFlag &ignoredFlag, 1296 const analyze_printf::OptionalFlag &flag, 1297 const char *startSpecifier, unsigned specifierLen); 1298}; 1299} 1300 1301bool CheckPrintfHandler::HandleInvalidPrintfConversionSpecifier( 1302 const analyze_printf::PrintfSpecifier &FS, 1303 const char *startSpecifier, 1304 unsigned specifierLen) { 1305 1306 unsigned argIndex = FS.getArgIndex(); 1307 bool keepGoing = true; 1308 if (argIndex < NumDataArgs) { 1309 // Consider the argument coverered, even though the specifier doesn't 1310 // make sense. 1311 CoveredArgs.set(argIndex); 1312 } 1313 else { 1314 // If argIndex exceeds the number of data arguments we 1315 // don't issue a warning because that is just a cascade of warnings (and 1316 // they may have intended '%%' anyway). We don't want to continue processing 1317 // the format string after this point, however, as we will like just get 1318 // gibberish when trying to match arguments. 1319 keepGoing = false; 1320 } 1321 1322 const analyze_printf::ConversionSpecifier &CS = 1323 FS.getConversionSpecifier(); 1324 SourceLocation Loc = getLocationOfByte(CS.getStart()); 1325 S.Diag(Loc, diag::warn_printf_invalid_conversion) 1326 << llvm::StringRef(CS.getStart(), CS.getLength()) 1327 << getSpecifierRange(startSpecifier, specifierLen); 1328 1329 return keepGoing; 1330} 1331 1332bool CheckPrintfHandler::HandleAmount( 1333 const analyze_format_string::OptionalAmount &Amt, 1334 unsigned k, const char *startSpecifier, 1335 unsigned specifierLen) { 1336 1337 if (Amt.hasDataArgument()) { 1338 if (!HasVAListArg) { 1339 unsigned argIndex = Amt.getArgIndex(); 1340 if (argIndex >= NumDataArgs) { 1341 S.Diag(getLocationOfByte(Amt.getStart()), 1342 diag::warn_printf_asterisk_missing_arg) 1343 << k << getSpecifierRange(startSpecifier, specifierLen); 1344 // Don't do any more checking. We will just emit 1345 // spurious errors. 1346 return false; 1347 } 1348 1349 // Type check the data argument. It should be an 'int'. 1350 // Although not in conformance with C99, we also allow the argument to be 1351 // an 'unsigned int' as that is a reasonably safe case. GCC also 1352 // doesn't emit a warning for that case. 1353 CoveredArgs.set(argIndex); 1354 const Expr *Arg = getDataArg(argIndex); 1355 QualType T = Arg->getType(); 1356 1357 const analyze_printf::ArgTypeResult &ATR = Amt.getArgType(S.Context); 1358 assert(ATR.isValid()); 1359 1360 if (!ATR.matchesType(S.Context, T)) { 1361 S.Diag(getLocationOfByte(Amt.getStart()), 1362 diag::warn_printf_asterisk_wrong_type) 1363 << k 1364 << ATR.getRepresentativeType(S.Context) << T 1365 << getSpecifierRange(startSpecifier, specifierLen) 1366 << Arg->getSourceRange(); 1367 // Don't do any more checking. We will just emit 1368 // spurious errors. 1369 return false; 1370 } 1371 } 1372 } 1373 return true; 1374} 1375 1376void CheckPrintfHandler::HandleInvalidAmount( 1377 const analyze_printf::PrintfSpecifier &FS, 1378 const analyze_printf::OptionalAmount &Amt, 1379 unsigned type, 1380 const char *startSpecifier, 1381 unsigned specifierLen) { 1382 const analyze_printf::ConversionSpecifier &CS = FS.getConversionSpecifier(); 1383 switch (Amt.getHowSpecified()) { 1384 case analyze_printf::OptionalAmount::Constant: 1385 S.Diag(getLocationOfByte(Amt.getStart()), 1386 diag::warn_printf_nonsensical_optional_amount) 1387 << type 1388 << CS.toString() 1389 << getSpecifierRange(startSpecifier, specifierLen) 1390 << FixItHint::CreateRemoval(getSpecifierRange(Amt.getStart(), 1391 Amt.getConstantLength())); 1392 break; 1393 1394 default: 1395 S.Diag(getLocationOfByte(Amt.getStart()), 1396 diag::warn_printf_nonsensical_optional_amount) 1397 << type 1398 << CS.toString() 1399 << getSpecifierRange(startSpecifier, specifierLen); 1400 break; 1401 } 1402} 1403 1404void CheckPrintfHandler::HandleFlag(const analyze_printf::PrintfSpecifier &FS, 1405 const analyze_printf::OptionalFlag &flag, 1406 const char *startSpecifier, 1407 unsigned specifierLen) { 1408 // Warn about pointless flag with a fixit removal. 1409 const analyze_printf::ConversionSpecifier &CS = FS.getConversionSpecifier(); 1410 S.Diag(getLocationOfByte(flag.getPosition()), 1411 diag::warn_printf_nonsensical_flag) 1412 << flag.toString() << CS.toString() 1413 << getSpecifierRange(startSpecifier, specifierLen) 1414 << FixItHint::CreateRemoval(getSpecifierRange(flag.getPosition(), 1)); 1415} 1416 1417void CheckPrintfHandler::HandleIgnoredFlag( 1418 const analyze_printf::PrintfSpecifier &FS, 1419 const analyze_printf::OptionalFlag &ignoredFlag, 1420 const analyze_printf::OptionalFlag &flag, 1421 const char *startSpecifier, 1422 unsigned specifierLen) { 1423 // Warn about ignored flag with a fixit removal. 1424 S.Diag(getLocationOfByte(ignoredFlag.getPosition()), 1425 diag::warn_printf_ignored_flag) 1426 << ignoredFlag.toString() << flag.toString() 1427 << getSpecifierRange(startSpecifier, specifierLen) 1428 << FixItHint::CreateRemoval(getSpecifierRange( 1429 ignoredFlag.getPosition(), 1)); 1430} 1431 1432bool 1433CheckPrintfHandler::HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier 1434 &FS, 1435 const char *startSpecifier, 1436 unsigned specifierLen) { 1437 1438 using namespace analyze_printf; 1439 const ConversionSpecifier &CS = FS.getConversionSpecifier(); 1440 1441 if (atFirstArg) { 1442 atFirstArg = false; 1443 usesPositionalArgs = FS.usesPositionalArg(); 1444 } 1445 else if (usesPositionalArgs != FS.usesPositionalArg()) { 1446 // Cannot mix-and-match positional and non-positional arguments. 1447 S.Diag(getLocationOfByte(CS.getStart()), 1448 diag::warn_format_mix_positional_nonpositional_args) 1449 << getSpecifierRange(startSpecifier, specifierLen); 1450 return false; 1451 } 1452 1453 // First check if the field width, precision, and conversion specifier 1454 // have matching data arguments. 1455 if (!HandleAmount(FS.getFieldWidth(), /* field width */ 0, 1456 startSpecifier, specifierLen)) { 1457 return false; 1458 } 1459 1460 if (!HandleAmount(FS.getPrecision(), /* precision */ 1, 1461 startSpecifier, specifierLen)) { 1462 return false; 1463 } 1464 1465 if (!CS.consumesDataArgument()) { 1466 // FIXME: Technically specifying a precision or field width here 1467 // makes no sense. Worth issuing a warning at some point. 1468 return true; 1469 } 1470 1471 // Consume the argument. 1472 unsigned argIndex = FS.getArgIndex(); 1473 if (argIndex < NumDataArgs) { 1474 // The check to see if the argIndex is valid will come later. 1475 // We set the bit here because we may exit early from this 1476 // function if we encounter some other error. 1477 CoveredArgs.set(argIndex); 1478 } 1479 1480 // Check for using an Objective-C specific conversion specifier 1481 // in a non-ObjC literal. 1482 if (!IsObjCLiteral && CS.isObjCArg()) { 1483 return HandleInvalidPrintfConversionSpecifier(FS, startSpecifier, 1484 specifierLen); 1485 } 1486 1487 // Check for invalid use of field width 1488 if (!FS.hasValidFieldWidth()) { 1489 HandleInvalidAmount(FS, FS.getFieldWidth(), /* field width */ 0, 1490 startSpecifier, specifierLen); 1491 } 1492 1493 // Check for invalid use of precision 1494 if (!FS.hasValidPrecision()) { 1495 HandleInvalidAmount(FS, FS.getPrecision(), /* precision */ 1, 1496 startSpecifier, specifierLen); 1497 } 1498 1499 // Check each flag does not conflict with any other component. 1500 if (!FS.hasValidLeadingZeros()) 1501 HandleFlag(FS, FS.hasLeadingZeros(), startSpecifier, specifierLen); 1502 if (!FS.hasValidPlusPrefix()) 1503 HandleFlag(FS, FS.hasPlusPrefix(), startSpecifier, specifierLen); 1504 if (!FS.hasValidSpacePrefix()) 1505 HandleFlag(FS, FS.hasSpacePrefix(), startSpecifier, specifierLen); 1506 if (!FS.hasValidAlternativeForm()) 1507 HandleFlag(FS, FS.hasAlternativeForm(), startSpecifier, specifierLen); 1508 if (!FS.hasValidLeftJustified()) 1509 HandleFlag(FS, FS.isLeftJustified(), startSpecifier, specifierLen); 1510 1511 // Check that flags are not ignored by another flag 1512 if (FS.hasSpacePrefix() && FS.hasPlusPrefix()) // ' ' ignored by '+' 1513 HandleIgnoredFlag(FS, FS.hasSpacePrefix(), FS.hasPlusPrefix(), 1514 startSpecifier, specifierLen); 1515 if (FS.hasLeadingZeros() && FS.isLeftJustified()) // '0' ignored by '-' 1516 HandleIgnoredFlag(FS, FS.hasLeadingZeros(), FS.isLeftJustified(), 1517 startSpecifier, specifierLen); 1518 1519 // Check the length modifier is valid with the given conversion specifier. 1520 const LengthModifier &LM = FS.getLengthModifier(); 1521 if (!FS.hasValidLengthModifier()) 1522 S.Diag(getLocationOfByte(LM.getStart()), 1523 diag::warn_printf_nonsensical_length) 1524 << LM.toString() << CS.toString() 1525 << getSpecifierRange(startSpecifier, specifierLen) 1526 << FixItHint::CreateRemoval(getSpecifierRange(LM.getStart(), 1527 LM.getLength())); 1528 1529 // Are we using '%n'? 1530 if (CS.getKind() == ConversionSpecifier::OutIntPtrArg) { 1531 // Issue a warning about this being a possible security issue. 1532 S.Diag(getLocationOfByte(CS.getStart()), diag::warn_printf_write_back) 1533 << getSpecifierRange(startSpecifier, specifierLen); 1534 // Continue checking the other format specifiers. 1535 return true; 1536 } 1537 1538 // The remaining checks depend on the data arguments. 1539 if (HasVAListArg) 1540 return true; 1541 1542 if (argIndex >= NumDataArgs) { 1543 if (FS.usesPositionalArg()) { 1544 S.Diag(getLocationOfByte(CS.getStart()), 1545 diag::warn_printf_positional_arg_exceeds_data_args) 1546 << (argIndex+1) << NumDataArgs 1547 << getSpecifierRange(startSpecifier, specifierLen); 1548 } 1549 else { 1550 S.Diag(getLocationOfByte(CS.getStart()), 1551 diag::warn_printf_insufficient_data_args) 1552 << getSpecifierRange(startSpecifier, specifierLen); 1553 } 1554 1555 // Don't do any more checking. 1556 return false; 1557 } 1558 1559 // Now type check the data expression that matches the 1560 // format specifier. 1561 const Expr *Ex = getDataArg(argIndex); 1562 const analyze_printf::ArgTypeResult &ATR = FS.getArgType(S.Context); 1563 if (ATR.isValid() && !ATR.matchesType(S.Context, Ex->getType())) { 1564 // Check if we didn't match because of an implicit cast from a 'char' 1565 // or 'short' to an 'int'. This is done because printf is a varargs 1566 // function. 1567 if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Ex)) 1568 if (ICE->getType() == S.Context.IntTy) 1569 if (ATR.matchesType(S.Context, ICE->getSubExpr()->getType())) 1570 return true; 1571 1572 // We may be able to offer a FixItHint if it is a supported type. 1573 PrintfSpecifier fixedFS = FS; 1574 bool success = fixedFS.fixType(Ex->getType()); 1575 1576 if (success) { 1577 // Get the fix string from the fixed format specifier 1578 llvm::SmallString<128> buf; 1579 llvm::raw_svector_ostream os(buf); 1580 fixedFS.toString(os); 1581 1582 S.Diag(getLocationOfByte(CS.getStart()), 1583 diag::warn_printf_conversion_argument_type_mismatch) 1584 << ATR.getRepresentativeType(S.Context) << Ex->getType() 1585 << getSpecifierRange(startSpecifier, specifierLen) 1586 << Ex->getSourceRange() 1587 << FixItHint::CreateReplacement( 1588 getSpecifierRange(startSpecifier, specifierLen), 1589 os.str()); 1590 } 1591 else { 1592 S.Diag(getLocationOfByte(CS.getStart()), 1593 diag::warn_printf_conversion_argument_type_mismatch) 1594 << ATR.getRepresentativeType(S.Context) << Ex->getType() 1595 << getSpecifierRange(startSpecifier, specifierLen) 1596 << Ex->getSourceRange(); 1597 } 1598 } 1599 1600 return true; 1601} 1602 1603//===--- CHECK: Scanf format string checking ------------------------------===// 1604 1605namespace { 1606class CheckScanfHandler : public CheckFormatHandler { 1607public: 1608 CheckScanfHandler(Sema &s, const StringLiteral *fexpr, 1609 const Expr *origFormatExpr, unsigned firstDataArg, 1610 unsigned numDataArgs, bool isObjCLiteral, 1611 const char *beg, bool hasVAListArg, 1612 const CallExpr *theCall, unsigned formatIdx) 1613 : CheckFormatHandler(s, fexpr, origFormatExpr, firstDataArg, 1614 numDataArgs, isObjCLiteral, beg, hasVAListArg, 1615 theCall, formatIdx) {} 1616 1617 bool HandleScanfSpecifier(const analyze_scanf::ScanfSpecifier &FS, 1618 const char *startSpecifier, 1619 unsigned specifierLen); 1620}; 1621} 1622 1623bool CheckScanfHandler::HandleScanfSpecifier( 1624 const analyze_scanf::ScanfSpecifier &FS, 1625 const char *startSpecifier, 1626 unsigned specifierLen) { 1627 1628 using namespace analyze_scanf; 1629 using namespace analyze_format_string; 1630 1631 const ConversionSpecifier &CS = FS.getConversionSpecifier(); 1632 1633 // FIXME: Handle case where '%' and '*' don't consume an argument. 1634 // This needs to be done for the printf case as well. 1635 if (atFirstArg) { 1636 atFirstArg = false; 1637 usesPositionalArgs = FS.usesPositionalArg(); 1638 } 1639 else if (usesPositionalArgs != FS.usesPositionalArg()) { 1640 // Cannot mix-and-match positional and non-positional arguments. 1641 S.Diag(getLocationOfByte(CS.getStart()), 1642 diag::warn_format_mix_positional_nonpositional_args) 1643 << getSpecifierRange(startSpecifier, specifierLen); 1644 return false; 1645 } 1646 1647 // Check if the field with is non-zero. 1648 const OptionalAmount &Amt = FS.getFieldWidth(); 1649 if (Amt.getHowSpecified() == OptionalAmount::Constant) { 1650 if (Amt.getConstantAmount() == 0) { 1651 const CharSourceRange &R = getSpecifierRange(Amt.getStart(), 1652 Amt.getConstantLength()); 1653 S.Diag(getLocationOfByte(Amt.getStart()), 1654 diag::warn_scanf_nonzero_width) 1655 << R << FixItHint::CreateRemoval(R); 1656 } 1657 } 1658 1659 if (!FS.consumesDataArgument()) { 1660 // FIXME: Technically specifying a precision or field width here 1661 // makes no sense. Worth issuing a warning at some point. 1662 return true; 1663 } 1664 1665 // Consume the argument. 1666 unsigned argIndex = FS.getArgIndex(); 1667 if (argIndex < NumDataArgs) { 1668 // The check to see if the argIndex is valid will come later. 1669 // We set the bit here because we may exit early from this 1670 // function if we encounter some other error. 1671 CoveredArgs.set(argIndex); 1672 } 1673 1674 // FIXME: Check that the length modifier is valid with the given 1675 // conversion specifier. 1676 1677 // The remaining checks depend on the data arguments. 1678 if (HasVAListArg) 1679 return true; 1680 1681 if (argIndex >= NumDataArgs) { 1682 if (FS.usesPositionalArg()) { 1683 S.Diag(getLocationOfByte(CS.getStart()), 1684 diag::warn_printf_positional_arg_exceeds_data_args) 1685 << (argIndex+1) << NumDataArgs 1686 << getSpecifierRange(startSpecifier, specifierLen); 1687 } 1688 else { 1689 S.Diag(getLocationOfByte(CS.getStart()), 1690 diag::warn_printf_insufficient_data_args) 1691 << getSpecifierRange(startSpecifier, specifierLen); 1692 } 1693 1694 // Don't do any more checking. 1695 return false; 1696 } 1697 1698 // FIXME: Check that the argument type matches the format specifier. 1699 1700 return true; 1701} 1702 1703void Sema::CheckFormatString(const StringLiteral *FExpr, 1704 const Expr *OrigFormatExpr, 1705 const CallExpr *TheCall, bool HasVAListArg, 1706 unsigned format_idx, unsigned firstDataArg, 1707 bool isPrintf) { 1708 1709 // CHECK: is the format string a wide literal? 1710 if (FExpr->isWide()) { 1711 Diag(FExpr->getLocStart(), 1712 diag::warn_format_string_is_wide_literal) 1713 << OrigFormatExpr->getSourceRange(); 1714 return; 1715 } 1716 1717 // Str - The format string. NOTE: this is NOT null-terminated! 1718 const char *Str = FExpr->getStrData(); 1719 1720 // CHECK: empty format string? 1721 unsigned StrLen = FExpr->getByteLength(); 1722 1723 if (StrLen == 0) { 1724 Diag(FExpr->getLocStart(), diag::warn_empty_format_string) 1725 << OrigFormatExpr->getSourceRange(); 1726 return; 1727 } 1728 1729 if (isPrintf) { 1730 CheckPrintfHandler H(*this, FExpr, OrigFormatExpr, firstDataArg, 1731 TheCall->getNumArgs() - firstDataArg, 1732 isa<ObjCStringLiteral>(OrigFormatExpr), Str, 1733 HasVAListArg, TheCall, format_idx); 1734 1735 if (!analyze_format_string::ParsePrintfString(H, Str, Str + StrLen)) 1736 H.DoneProcessing(); 1737 } 1738 else { 1739 CheckScanfHandler H(*this, FExpr, OrigFormatExpr, firstDataArg, 1740 TheCall->getNumArgs() - firstDataArg, 1741 isa<ObjCStringLiteral>(OrigFormatExpr), Str, 1742 HasVAListArg, TheCall, format_idx); 1743 1744 if (!analyze_format_string::ParseScanfString(H, Str, Str + StrLen)) 1745 H.DoneProcessing(); 1746 } 1747} 1748 1749//===--- CHECK: Return Address of Stack Variable --------------------------===// 1750 1751static DeclRefExpr* EvalVal(Expr *E); 1752static DeclRefExpr* EvalAddr(Expr* E); 1753 1754/// CheckReturnStackAddr - Check if a return statement returns the address 1755/// of a stack variable. 1756void 1757Sema::CheckReturnStackAddr(Expr *RetValExp, QualType lhsType, 1758 SourceLocation ReturnLoc) { 1759 1760 // Perform checking for returned stack addresses. 1761 if (lhsType->isPointerType() || lhsType->isBlockPointerType()) { 1762 if (DeclRefExpr *DR = EvalAddr(RetValExp)) 1763 Diag(DR->getLocStart(), diag::warn_ret_stack_addr) 1764 << DR->getDecl()->getDeclName() << RetValExp->getSourceRange(); 1765 1766 // Skip over implicit cast expressions when checking for block expressions. 1767 RetValExp = RetValExp->IgnoreParenCasts(); 1768 1769 if (BlockExpr *C = dyn_cast<BlockExpr>(RetValExp)) 1770 if (C->hasBlockDeclRefExprs()) 1771 Diag(C->getLocStart(), diag::err_ret_local_block) 1772 << C->getSourceRange(); 1773 1774 if (AddrLabelExpr *ALE = dyn_cast<AddrLabelExpr>(RetValExp)) 1775 Diag(ALE->getLocStart(), diag::warn_ret_addr_label) 1776 << ALE->getSourceRange(); 1777 1778 } else if (lhsType->isReferenceType()) { 1779 // Perform checking for stack values returned by reference. 1780 // Check for a reference to the stack 1781 if (DeclRefExpr *DR = EvalVal(RetValExp)) 1782 Diag(DR->getLocStart(), diag::warn_ret_stack_ref) 1783 << DR->getDecl()->getDeclName() << RetValExp->getSourceRange(); 1784 } 1785} 1786 1787/// EvalAddr - EvalAddr and EvalVal are mutually recursive functions that 1788/// check if the expression in a return statement evaluates to an address 1789/// to a location on the stack. The recursion is used to traverse the 1790/// AST of the return expression, with recursion backtracking when we 1791/// encounter a subexpression that (1) clearly does not lead to the address 1792/// of a stack variable or (2) is something we cannot determine leads to 1793/// the address of a stack variable based on such local checking. 1794/// 1795/// EvalAddr processes expressions that are pointers that are used as 1796/// references (and not L-values). EvalVal handles all other values. 1797/// At the base case of the recursion is a check for a DeclRefExpr* in 1798/// the refers to a stack variable. 1799/// 1800/// This implementation handles: 1801/// 1802/// * pointer-to-pointer casts 1803/// * implicit conversions from array references to pointers 1804/// * taking the address of fields 1805/// * arbitrary interplay between "&" and "*" operators 1806/// * pointer arithmetic from an address of a stack variable 1807/// * taking the address of an array element where the array is on the stack 1808static DeclRefExpr* EvalAddr(Expr *E) { 1809 // We should only be called for evaluating pointer expressions. 1810 assert((E->getType()->isAnyPointerType() || 1811 E->getType()->isBlockPointerType() || 1812 E->getType()->isObjCQualifiedIdType()) && 1813 "EvalAddr only works on pointers"); 1814 1815 // Our "symbolic interpreter" is just a dispatch off the currently 1816 // viewed AST node. We then recursively traverse the AST by calling 1817 // EvalAddr and EvalVal appropriately. 1818 switch (E->getStmtClass()) { 1819 case Stmt::ParenExprClass: 1820 // Ignore parentheses. 1821 return EvalAddr(cast<ParenExpr>(E)->getSubExpr()); 1822 1823 case Stmt::UnaryOperatorClass: { 1824 // The only unary operator that make sense to handle here 1825 // is AddrOf. All others don't make sense as pointers. 1826 UnaryOperator *U = cast<UnaryOperator>(E); 1827 1828 if (U->getOpcode() == UnaryOperator::AddrOf) 1829 return EvalVal(U->getSubExpr()); 1830 else 1831 return NULL; 1832 } 1833 1834 case Stmt::BinaryOperatorClass: { 1835 // Handle pointer arithmetic. All other binary operators are not valid 1836 // in this context. 1837 BinaryOperator *B = cast<BinaryOperator>(E); 1838 BinaryOperator::Opcode op = B->getOpcode(); 1839 1840 if (op != BinaryOperator::Add && op != BinaryOperator::Sub) 1841 return NULL; 1842 1843 Expr *Base = B->getLHS(); 1844 1845 // Determine which argument is the real pointer base. It could be 1846 // the RHS argument instead of the LHS. 1847 if (!Base->getType()->isPointerType()) Base = B->getRHS(); 1848 1849 assert (Base->getType()->isPointerType()); 1850 return EvalAddr(Base); 1851 } 1852 1853 // For conditional operators we need to see if either the LHS or RHS are 1854 // valid DeclRefExpr*s. If one of them is valid, we return it. 1855 case Stmt::ConditionalOperatorClass: { 1856 ConditionalOperator *C = cast<ConditionalOperator>(E); 1857 1858 // Handle the GNU extension for missing LHS. 1859 if (Expr *lhsExpr = C->getLHS()) 1860 if (DeclRefExpr* LHS = EvalAddr(lhsExpr)) 1861 return LHS; 1862 1863 return EvalAddr(C->getRHS()); 1864 } 1865 1866 // For casts, we need to handle conversions from arrays to 1867 // pointer values, and pointer-to-pointer conversions. 1868 case Stmt::ImplicitCastExprClass: 1869 case Stmt::CStyleCastExprClass: 1870 case Stmt::CXXFunctionalCastExprClass: { 1871 Expr* SubExpr = cast<CastExpr>(E)->getSubExpr(); 1872 QualType T = SubExpr->getType(); 1873 1874 if (SubExpr->getType()->isPointerType() || 1875 SubExpr->getType()->isBlockPointerType() || 1876 SubExpr->getType()->isObjCQualifiedIdType()) 1877 return EvalAddr(SubExpr); 1878 else if (T->isArrayType()) 1879 return EvalVal(SubExpr); 1880 else 1881 return 0; 1882 } 1883 1884 // C++ casts. For dynamic casts, static casts, and const casts, we 1885 // are always converting from a pointer-to-pointer, so we just blow 1886 // through the cast. In the case the dynamic cast doesn't fail (and 1887 // return NULL), we take the conservative route and report cases 1888 // where we return the address of a stack variable. For Reinterpre 1889 // FIXME: The comment about is wrong; we're not always converting 1890 // from pointer to pointer. I'm guessing that this code should also 1891 // handle references to objects. 1892 case Stmt::CXXStaticCastExprClass: 1893 case Stmt::CXXDynamicCastExprClass: 1894 case Stmt::CXXConstCastExprClass: 1895 case Stmt::CXXReinterpretCastExprClass: { 1896 Expr *S = cast<CXXNamedCastExpr>(E)->getSubExpr(); 1897 if (S->getType()->isPointerType() || S->getType()->isBlockPointerType()) 1898 return EvalAddr(S); 1899 else 1900 return NULL; 1901 } 1902 1903 // Everything else: we simply don't reason about them. 1904 default: 1905 return NULL; 1906 } 1907} 1908 1909 1910/// EvalVal - This function is complements EvalAddr in the mutual recursion. 1911/// See the comments for EvalAddr for more details. 1912static DeclRefExpr* EvalVal(Expr *E) { 1913 1914 // We should only be called for evaluating non-pointer expressions, or 1915 // expressions with a pointer type that are not used as references but instead 1916 // are l-values (e.g., DeclRefExpr with a pointer type). 1917 1918 // Our "symbolic interpreter" is just a dispatch off the currently 1919 // viewed AST node. We then recursively traverse the AST by calling 1920 // EvalAddr and EvalVal appropriately. 1921 switch (E->getStmtClass()) { 1922 case Stmt::DeclRefExprClass: { 1923 // DeclRefExpr: the base case. When we hit a DeclRefExpr we are looking 1924 // at code that refers to a variable's name. We check if it has local 1925 // storage within the function, and if so, return the expression. 1926 DeclRefExpr *DR = cast<DeclRefExpr>(E); 1927 1928 if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl())) 1929 if (V->hasLocalStorage() && !V->getType()->isReferenceType()) return DR; 1930 1931 return NULL; 1932 } 1933 1934 case Stmt::ParenExprClass: 1935 // Ignore parentheses. 1936 return EvalVal(cast<ParenExpr>(E)->getSubExpr()); 1937 1938 case Stmt::UnaryOperatorClass: { 1939 // The only unary operator that make sense to handle here 1940 // is Deref. All others don't resolve to a "name." This includes 1941 // handling all sorts of rvalues passed to a unary operator. 1942 UnaryOperator *U = cast<UnaryOperator>(E); 1943 1944 if (U->getOpcode() == UnaryOperator::Deref) 1945 return EvalAddr(U->getSubExpr()); 1946 1947 return NULL; 1948 } 1949 1950 case Stmt::ArraySubscriptExprClass: { 1951 // Array subscripts are potential references to data on the stack. We 1952 // retrieve the DeclRefExpr* for the array variable if it indeed 1953 // has local storage. 1954 return EvalAddr(cast<ArraySubscriptExpr>(E)->getBase()); 1955 } 1956 1957 case Stmt::ConditionalOperatorClass: { 1958 // For conditional operators we need to see if either the LHS or RHS are 1959 // non-NULL DeclRefExpr's. If one is non-NULL, we return it. 1960 ConditionalOperator *C = cast<ConditionalOperator>(E); 1961 1962 // Handle the GNU extension for missing LHS. 1963 if (Expr *lhsExpr = C->getLHS()) 1964 if (DeclRefExpr *LHS = EvalVal(lhsExpr)) 1965 return LHS; 1966 1967 return EvalVal(C->getRHS()); 1968 } 1969 1970 // Accesses to members are potential references to data on the stack. 1971 case Stmt::MemberExprClass: { 1972 MemberExpr *M = cast<MemberExpr>(E); 1973 1974 // Check for indirect access. We only want direct field accesses. 1975 if (!M->isArrow()) 1976 return EvalVal(M->getBase()); 1977 else 1978 return NULL; 1979 } 1980 1981 // Everything else: we simply don't reason about them. 1982 default: 1983 return NULL; 1984 } 1985} 1986 1987//===--- CHECK: Floating-Point comparisons (-Wfloat-equal) ---------------===// 1988 1989/// Check for comparisons of floating point operands using != and ==. 1990/// Issue a warning if these are no self-comparisons, as they are not likely 1991/// to do what the programmer intended. 1992void Sema::CheckFloatComparison(SourceLocation loc, Expr* lex, Expr *rex) { 1993 bool EmitWarning = true; 1994 1995 Expr* LeftExprSansParen = lex->IgnoreParens(); 1996 Expr* RightExprSansParen = rex->IgnoreParens(); 1997 1998 // Special case: check for x == x (which is OK). 1999 // Do not emit warnings for such cases. 2000 if (DeclRefExpr* DRL = dyn_cast<DeclRefExpr>(LeftExprSansParen)) 2001 if (DeclRefExpr* DRR = dyn_cast<DeclRefExpr>(RightExprSansParen)) 2002 if (DRL->getDecl() == DRR->getDecl()) 2003 EmitWarning = false; 2004 2005 2006 // Special case: check for comparisons against literals that can be exactly 2007 // represented by APFloat. In such cases, do not emit a warning. This 2008 // is a heuristic: often comparison against such literals are used to 2009 // detect if a value in a variable has not changed. This clearly can 2010 // lead to false negatives. 2011 if (EmitWarning) { 2012 if (FloatingLiteral* FLL = dyn_cast<FloatingLiteral>(LeftExprSansParen)) { 2013 if (FLL->isExact()) 2014 EmitWarning = false; 2015 } else 2016 if (FloatingLiteral* FLR = dyn_cast<FloatingLiteral>(RightExprSansParen)){ 2017 if (FLR->isExact()) 2018 EmitWarning = false; 2019 } 2020 } 2021 2022 // Check for comparisons with builtin types. 2023 if (EmitWarning) 2024 if (CallExpr* CL = dyn_cast<CallExpr>(LeftExprSansParen)) 2025 if (CL->isBuiltinCall(Context)) 2026 EmitWarning = false; 2027 2028 if (EmitWarning) 2029 if (CallExpr* CR = dyn_cast<CallExpr>(RightExprSansParen)) 2030 if (CR->isBuiltinCall(Context)) 2031 EmitWarning = false; 2032 2033 // Emit the diagnostic. 2034 if (EmitWarning) 2035 Diag(loc, diag::warn_floatingpoint_eq) 2036 << lex->getSourceRange() << rex->getSourceRange(); 2037} 2038 2039//===--- CHECK: Integer mixed-sign comparisons (-Wsign-compare) --------===// 2040//===--- CHECK: Lossy implicit conversions (-Wconversion) --------------===// 2041 2042namespace { 2043 2044/// Structure recording the 'active' range of an integer-valued 2045/// expression. 2046struct IntRange { 2047 /// The number of bits active in the int. 2048 unsigned Width; 2049 2050 /// True if the int is known not to have negative values. 2051 bool NonNegative; 2052 2053 IntRange() {} 2054 IntRange(unsigned Width, bool NonNegative) 2055 : Width(Width), NonNegative(NonNegative) 2056 {} 2057 2058 // Returns the range of the bool type. 2059 static IntRange forBoolType() { 2060 return IntRange(1, true); 2061 } 2062 2063 // Returns the range of an integral type. 2064 static IntRange forType(ASTContext &C, QualType T) { 2065 return forCanonicalType(C, T->getCanonicalTypeInternal().getTypePtr()); 2066 } 2067 2068 // Returns the range of an integeral type based on its canonical 2069 // representation. 2070 static IntRange forCanonicalType(ASTContext &C, const Type *T) { 2071 assert(T->isCanonicalUnqualified()); 2072 2073 if (const VectorType *VT = dyn_cast<VectorType>(T)) 2074 T = VT->getElementType().getTypePtr(); 2075 if (const ComplexType *CT = dyn_cast<ComplexType>(T)) 2076 T = CT->getElementType().getTypePtr(); 2077 2078 if (const EnumType *ET = dyn_cast<EnumType>(T)) { 2079 EnumDecl *Enum = ET->getDecl(); 2080 unsigned NumPositive = Enum->getNumPositiveBits(); 2081 unsigned NumNegative = Enum->getNumNegativeBits(); 2082 2083 return IntRange(std::max(NumPositive, NumNegative), NumNegative == 0); 2084 } 2085 2086 const BuiltinType *BT = cast<BuiltinType>(T); 2087 assert(BT->isInteger()); 2088 2089 return IntRange(C.getIntWidth(QualType(T, 0)), BT->isUnsignedInteger()); 2090 } 2091 2092 // Returns the supremum of two ranges: i.e. their conservative merge. 2093 static IntRange join(IntRange L, IntRange R) { 2094 return IntRange(std::max(L.Width, R.Width), 2095 L.NonNegative && R.NonNegative); 2096 } 2097 2098 // Returns the infinum of two ranges: i.e. their aggressive merge. 2099 static IntRange meet(IntRange L, IntRange R) { 2100 return IntRange(std::min(L.Width, R.Width), 2101 L.NonNegative || R.NonNegative); 2102 } 2103}; 2104 2105IntRange GetValueRange(ASTContext &C, llvm::APSInt &value, unsigned MaxWidth) { 2106 if (value.isSigned() && value.isNegative()) 2107 return IntRange(value.getMinSignedBits(), false); 2108 2109 if (value.getBitWidth() > MaxWidth) 2110 value.trunc(MaxWidth); 2111 2112 // isNonNegative() just checks the sign bit without considering 2113 // signedness. 2114 return IntRange(value.getActiveBits(), true); 2115} 2116 2117IntRange GetValueRange(ASTContext &C, APValue &result, QualType Ty, 2118 unsigned MaxWidth) { 2119 if (result.isInt()) 2120 return GetValueRange(C, result.getInt(), MaxWidth); 2121 2122 if (result.isVector()) { 2123 IntRange R = GetValueRange(C, result.getVectorElt(0), Ty, MaxWidth); 2124 for (unsigned i = 1, e = result.getVectorLength(); i != e; ++i) { 2125 IntRange El = GetValueRange(C, result.getVectorElt(i), Ty, MaxWidth); 2126 R = IntRange::join(R, El); 2127 } 2128 return R; 2129 } 2130 2131 if (result.isComplexInt()) { 2132 IntRange R = GetValueRange(C, result.getComplexIntReal(), MaxWidth); 2133 IntRange I = GetValueRange(C, result.getComplexIntImag(), MaxWidth); 2134 return IntRange::join(R, I); 2135 } 2136 2137 // This can happen with lossless casts to intptr_t of "based" lvalues. 2138 // Assume it might use arbitrary bits. 2139 // FIXME: The only reason we need to pass the type in here is to get 2140 // the sign right on this one case. It would be nice if APValue 2141 // preserved this. 2142 assert(result.isLValue()); 2143 return IntRange(MaxWidth, Ty->isUnsignedIntegerType()); 2144} 2145 2146/// Pseudo-evaluate the given integer expression, estimating the 2147/// range of values it might take. 2148/// 2149/// \param MaxWidth - the width to which the value will be truncated 2150IntRange GetExprRange(ASTContext &C, Expr *E, unsigned MaxWidth) { 2151 E = E->IgnoreParens(); 2152 2153 // Try a full evaluation first. 2154 Expr::EvalResult result; 2155 if (E->Evaluate(result, C)) 2156 return GetValueRange(C, result.Val, E->getType(), MaxWidth); 2157 2158 // I think we only want to look through implicit casts here; if the 2159 // user has an explicit widening cast, we should treat the value as 2160 // being of the new, wider type. 2161 if (ImplicitCastExpr *CE = dyn_cast<ImplicitCastExpr>(E)) { 2162 if (CE->getCastKind() == CastExpr::CK_NoOp) 2163 return GetExprRange(C, CE->getSubExpr(), MaxWidth); 2164 2165 IntRange OutputTypeRange = IntRange::forType(C, CE->getType()); 2166 2167 bool isIntegerCast = (CE->getCastKind() == CastExpr::CK_IntegralCast); 2168 if (!isIntegerCast && CE->getCastKind() == CastExpr::CK_Unknown) 2169 isIntegerCast = CE->getSubExpr()->getType()->isIntegerType(); 2170 2171 // Assume that non-integer casts can span the full range of the type. 2172 if (!isIntegerCast) 2173 return OutputTypeRange; 2174 2175 IntRange SubRange 2176 = GetExprRange(C, CE->getSubExpr(), 2177 std::min(MaxWidth, OutputTypeRange.Width)); 2178 2179 // Bail out if the subexpr's range is as wide as the cast type. 2180 if (SubRange.Width >= OutputTypeRange.Width) 2181 return OutputTypeRange; 2182 2183 // Otherwise, we take the smaller width, and we're non-negative if 2184 // either the output type or the subexpr is. 2185 return IntRange(SubRange.Width, 2186 SubRange.NonNegative || OutputTypeRange.NonNegative); 2187 } 2188 2189 if (ConditionalOperator *CO = dyn_cast<ConditionalOperator>(E)) { 2190 // If we can fold the condition, just take that operand. 2191 bool CondResult; 2192 if (CO->getCond()->EvaluateAsBooleanCondition(CondResult, C)) 2193 return GetExprRange(C, CondResult ? CO->getTrueExpr() 2194 : CO->getFalseExpr(), 2195 MaxWidth); 2196 2197 // Otherwise, conservatively merge. 2198 IntRange L = GetExprRange(C, CO->getTrueExpr(), MaxWidth); 2199 IntRange R = GetExprRange(C, CO->getFalseExpr(), MaxWidth); 2200 return IntRange::join(L, R); 2201 } 2202 2203 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) { 2204 switch (BO->getOpcode()) { 2205 2206 // Boolean-valued operations are single-bit and positive. 2207 case BinaryOperator::LAnd: 2208 case BinaryOperator::LOr: 2209 case BinaryOperator::LT: 2210 case BinaryOperator::GT: 2211 case BinaryOperator::LE: 2212 case BinaryOperator::GE: 2213 case BinaryOperator::EQ: 2214 case BinaryOperator::NE: 2215 return IntRange::forBoolType(); 2216 2217 // The type of these compound assignments is the type of the LHS, 2218 // so the RHS is not necessarily an integer. 2219 case BinaryOperator::MulAssign: 2220 case BinaryOperator::DivAssign: 2221 case BinaryOperator::RemAssign: 2222 case BinaryOperator::AddAssign: 2223 case BinaryOperator::SubAssign: 2224 return IntRange::forType(C, E->getType()); 2225 2226 // Operations with opaque sources are black-listed. 2227 case BinaryOperator::PtrMemD: 2228 case BinaryOperator::PtrMemI: 2229 return IntRange::forType(C, E->getType()); 2230 2231 // Bitwise-and uses the *infinum* of the two source ranges. 2232 case BinaryOperator::And: 2233 case BinaryOperator::AndAssign: 2234 return IntRange::meet(GetExprRange(C, BO->getLHS(), MaxWidth), 2235 GetExprRange(C, BO->getRHS(), MaxWidth)); 2236 2237 // Left shift gets black-listed based on a judgement call. 2238 case BinaryOperator::Shl: 2239 // ...except that we want to treat '1 << (blah)' as logically 2240 // positive. It's an important idiom. 2241 if (IntegerLiteral *I 2242 = dyn_cast<IntegerLiteral>(BO->getLHS()->IgnoreParenCasts())) { 2243 if (I->getValue() == 1) { 2244 IntRange R = IntRange::forType(C, E->getType()); 2245 return IntRange(R.Width, /*NonNegative*/ true); 2246 } 2247 } 2248 // fallthrough 2249 2250 case BinaryOperator::ShlAssign: 2251 return IntRange::forType(C, E->getType()); 2252 2253 // Right shift by a constant can narrow its left argument. 2254 case BinaryOperator::Shr: 2255 case BinaryOperator::ShrAssign: { 2256 IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth); 2257 2258 // If the shift amount is a positive constant, drop the width by 2259 // that much. 2260 llvm::APSInt shift; 2261 if (BO->getRHS()->isIntegerConstantExpr(shift, C) && 2262 shift.isNonNegative()) { 2263 unsigned zext = shift.getZExtValue(); 2264 if (zext >= L.Width) 2265 L.Width = (L.NonNegative ? 0 : 1); 2266 else 2267 L.Width -= zext; 2268 } 2269 2270 return L; 2271 } 2272 2273 // Comma acts as its right operand. 2274 case BinaryOperator::Comma: 2275 return GetExprRange(C, BO->getRHS(), MaxWidth); 2276 2277 // Black-list pointer subtractions. 2278 case BinaryOperator::Sub: 2279 if (BO->getLHS()->getType()->isPointerType()) 2280 return IntRange::forType(C, E->getType()); 2281 // fallthrough 2282 2283 default: 2284 break; 2285 } 2286 2287 // Treat every other operator as if it were closed on the 2288 // narrowest type that encompasses both operands. 2289 IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth); 2290 IntRange R = GetExprRange(C, BO->getRHS(), MaxWidth); 2291 return IntRange::join(L, R); 2292 } 2293 2294 if (UnaryOperator *UO = dyn_cast<UnaryOperator>(E)) { 2295 switch (UO->getOpcode()) { 2296 // Boolean-valued operations are white-listed. 2297 case UnaryOperator::LNot: 2298 return IntRange::forBoolType(); 2299 2300 // Operations with opaque sources are black-listed. 2301 case UnaryOperator::Deref: 2302 case UnaryOperator::AddrOf: // should be impossible 2303 case UnaryOperator::OffsetOf: 2304 return IntRange::forType(C, E->getType()); 2305 2306 default: 2307 return GetExprRange(C, UO->getSubExpr(), MaxWidth); 2308 } 2309 } 2310 2311 if (dyn_cast<OffsetOfExpr>(E)) { 2312 IntRange::forType(C, E->getType()); 2313 } 2314 2315 FieldDecl *BitField = E->getBitField(); 2316 if (BitField) { 2317 llvm::APSInt BitWidthAP = BitField->getBitWidth()->EvaluateAsInt(C); 2318 unsigned BitWidth = BitWidthAP.getZExtValue(); 2319 2320 return IntRange(BitWidth, BitField->getType()->isUnsignedIntegerType()); 2321 } 2322 2323 return IntRange::forType(C, E->getType()); 2324} 2325 2326IntRange GetExprRange(ASTContext &C, Expr *E) { 2327 return GetExprRange(C, E, C.getIntWidth(E->getType())); 2328} 2329 2330/// Checks whether the given value, which currently has the given 2331/// source semantics, has the same value when coerced through the 2332/// target semantics. 2333bool IsSameFloatAfterCast(const llvm::APFloat &value, 2334 const llvm::fltSemantics &Src, 2335 const llvm::fltSemantics &Tgt) { 2336 llvm::APFloat truncated = value; 2337 2338 bool ignored; 2339 truncated.convert(Src, llvm::APFloat::rmNearestTiesToEven, &ignored); 2340 truncated.convert(Tgt, llvm::APFloat::rmNearestTiesToEven, &ignored); 2341 2342 return truncated.bitwiseIsEqual(value); 2343} 2344 2345/// Checks whether the given value, which currently has the given 2346/// source semantics, has the same value when coerced through the 2347/// target semantics. 2348/// 2349/// The value might be a vector of floats (or a complex number). 2350bool IsSameFloatAfterCast(const APValue &value, 2351 const llvm::fltSemantics &Src, 2352 const llvm::fltSemantics &Tgt) { 2353 if (value.isFloat()) 2354 return IsSameFloatAfterCast(value.getFloat(), Src, Tgt); 2355 2356 if (value.isVector()) { 2357 for (unsigned i = 0, e = value.getVectorLength(); i != e; ++i) 2358 if (!IsSameFloatAfterCast(value.getVectorElt(i), Src, Tgt)) 2359 return false; 2360 return true; 2361 } 2362 2363 assert(value.isComplexFloat()); 2364 return (IsSameFloatAfterCast(value.getComplexFloatReal(), Src, Tgt) && 2365 IsSameFloatAfterCast(value.getComplexFloatImag(), Src, Tgt)); 2366} 2367 2368void AnalyzeImplicitConversions(Sema &S, Expr *E); 2369 2370bool IsZero(Sema &S, Expr *E) { 2371 llvm::APSInt Value; 2372 return E->isIntegerConstantExpr(Value, S.Context) && Value == 0; 2373} 2374 2375void CheckTrivialUnsignedComparison(Sema &S, BinaryOperator *E) { 2376 BinaryOperator::Opcode op = E->getOpcode(); 2377 if (op == BinaryOperator::LT && IsZero(S, E->getRHS())) { 2378 S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison) 2379 << "< 0" << "false" 2380 << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); 2381 } else if (op == BinaryOperator::GE && IsZero(S, E->getRHS())) { 2382 S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison) 2383 << ">= 0" << "true" 2384 << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); 2385 } else if (op == BinaryOperator::GT && IsZero(S, E->getLHS())) { 2386 S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison) 2387 << "0 >" << "false" 2388 << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); 2389 } else if (op == BinaryOperator::LE && IsZero(S, E->getLHS())) { 2390 S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison) 2391 << "0 <=" << "true" 2392 << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); 2393 } 2394} 2395 2396/// Analyze the operands of the given comparison. Implements the 2397/// fallback case from AnalyzeComparison. 2398void AnalyzeImpConvsInComparison(Sema &S, BinaryOperator *E) { 2399 AnalyzeImplicitConversions(S, E->getLHS()); 2400 AnalyzeImplicitConversions(S, E->getRHS()); 2401} 2402 2403/// \brief Implements -Wsign-compare. 2404/// 2405/// \param lex the left-hand expression 2406/// \param rex the right-hand expression 2407/// \param OpLoc the location of the joining operator 2408/// \param BinOpc binary opcode or 0 2409void AnalyzeComparison(Sema &S, BinaryOperator *E) { 2410 // The type the comparison is being performed in. 2411 QualType T = E->getLHS()->getType(); 2412 assert(S.Context.hasSameUnqualifiedType(T, E->getRHS()->getType()) 2413 && "comparison with mismatched types"); 2414 2415 // We don't do anything special if this isn't an unsigned integral 2416 // comparison: we're only interested in integral comparisons, and 2417 // signed comparisons only happen in cases we don't care to warn about. 2418 if (!T->isUnsignedIntegerType()) 2419 return AnalyzeImpConvsInComparison(S, E); 2420 2421 Expr *lex = E->getLHS()->IgnoreParenImpCasts(); 2422 Expr *rex = E->getRHS()->IgnoreParenImpCasts(); 2423 2424 // Check to see if one of the (unmodified) operands is of different 2425 // signedness. 2426 Expr *signedOperand, *unsignedOperand; 2427 if (lex->getType()->isSignedIntegerType()) { 2428 assert(!rex->getType()->isSignedIntegerType() && 2429 "unsigned comparison between two signed integer expressions?"); 2430 signedOperand = lex; 2431 unsignedOperand = rex; 2432 } else if (rex->getType()->isSignedIntegerType()) { 2433 signedOperand = rex; 2434 unsignedOperand = lex; 2435 } else { 2436 CheckTrivialUnsignedComparison(S, E); 2437 return AnalyzeImpConvsInComparison(S, E); 2438 } 2439 2440 // Otherwise, calculate the effective range of the signed operand. 2441 IntRange signedRange = GetExprRange(S.Context, signedOperand); 2442 2443 // Go ahead and analyze implicit conversions in the operands. Note 2444 // that we skip the implicit conversions on both sides. 2445 AnalyzeImplicitConversions(S, lex); 2446 AnalyzeImplicitConversions(S, rex); 2447 2448 // If the signed range is non-negative, -Wsign-compare won't fire, 2449 // but we should still check for comparisons which are always true 2450 // or false. 2451 if (signedRange.NonNegative) 2452 return CheckTrivialUnsignedComparison(S, E); 2453 2454 // For (in)equality comparisons, if the unsigned operand is a 2455 // constant which cannot collide with a overflowed signed operand, 2456 // then reinterpreting the signed operand as unsigned will not 2457 // change the result of the comparison. 2458 if (E->isEqualityOp()) { 2459 unsigned comparisonWidth = S.Context.getIntWidth(T); 2460 IntRange unsignedRange = GetExprRange(S.Context, unsignedOperand); 2461 2462 // We should never be unable to prove that the unsigned operand is 2463 // non-negative. 2464 assert(unsignedRange.NonNegative && "unsigned range includes negative?"); 2465 2466 if (unsignedRange.Width < comparisonWidth) 2467 return; 2468 } 2469 2470 S.Diag(E->getOperatorLoc(), diag::warn_mixed_sign_comparison) 2471 << lex->getType() << rex->getType() 2472 << lex->getSourceRange() << rex->getSourceRange(); 2473} 2474 2475/// Diagnose an implicit cast; purely a helper for CheckImplicitConversion. 2476void DiagnoseImpCast(Sema &S, Expr *E, QualType T, unsigned diag) { 2477 S.Diag(E->getExprLoc(), diag) << E->getType() << T << E->getSourceRange(); 2478} 2479 2480void CheckImplicitConversion(Sema &S, Expr *E, QualType T, 2481 bool *ICContext = 0) { 2482 if (E->isTypeDependent() || E->isValueDependent()) return; 2483 2484 const Type *Source = S.Context.getCanonicalType(E->getType()).getTypePtr(); 2485 const Type *Target = S.Context.getCanonicalType(T).getTypePtr(); 2486 if (Source == Target) return; 2487 if (Target->isDependentType()) return; 2488 2489 // Never diagnose implicit casts to bool. 2490 if (Target->isSpecificBuiltinType(BuiltinType::Bool)) 2491 return; 2492 2493 // Strip vector types. 2494 if (isa<VectorType>(Source)) { 2495 if (!isa<VectorType>(Target)) 2496 return DiagnoseImpCast(S, E, T, diag::warn_impcast_vector_scalar); 2497 2498 Source = cast<VectorType>(Source)->getElementType().getTypePtr(); 2499 Target = cast<VectorType>(Target)->getElementType().getTypePtr(); 2500 } 2501 2502 // Strip complex types. 2503 if (isa<ComplexType>(Source)) { 2504 if (!isa<ComplexType>(Target)) 2505 return DiagnoseImpCast(S, E, T, diag::warn_impcast_complex_scalar); 2506 2507 Source = cast<ComplexType>(Source)->getElementType().getTypePtr(); 2508 Target = cast<ComplexType>(Target)->getElementType().getTypePtr(); 2509 } 2510 2511 const BuiltinType *SourceBT = dyn_cast<BuiltinType>(Source); 2512 const BuiltinType *TargetBT = dyn_cast<BuiltinType>(Target); 2513 2514 // If the source is floating point... 2515 if (SourceBT && SourceBT->isFloatingPoint()) { 2516 // ...and the target is floating point... 2517 if (TargetBT && TargetBT->isFloatingPoint()) { 2518 // ...then warn if we're dropping FP rank. 2519 2520 // Builtin FP kinds are ordered by increasing FP rank. 2521 if (SourceBT->getKind() > TargetBT->getKind()) { 2522 // Don't warn about float constants that are precisely 2523 // representable in the target type. 2524 Expr::EvalResult result; 2525 if (E->Evaluate(result, S.Context)) { 2526 // Value might be a float, a float vector, or a float complex. 2527 if (IsSameFloatAfterCast(result.Val, 2528 S.Context.getFloatTypeSemantics(QualType(TargetBT, 0)), 2529 S.Context.getFloatTypeSemantics(QualType(SourceBT, 0)))) 2530 return; 2531 } 2532 2533 DiagnoseImpCast(S, E, T, diag::warn_impcast_float_precision); 2534 } 2535 return; 2536 } 2537 2538 // If the target is integral, always warn. 2539 if ((TargetBT && TargetBT->isInteger())) 2540 // TODO: don't warn for integer values? 2541 DiagnoseImpCast(S, E, T, diag::warn_impcast_float_integer); 2542 2543 return; 2544 } 2545 2546 if (!Source->isIntegerType() || !Target->isIntegerType()) 2547 return; 2548 2549 IntRange SourceRange = GetExprRange(S.Context, E); 2550 IntRange TargetRange = IntRange::forCanonicalType(S.Context, Target); 2551 2552 if (SourceRange.Width > TargetRange.Width) { 2553 // People want to build with -Wshorten-64-to-32 and not -Wconversion 2554 // and by god we'll let them. 2555 if (SourceRange.Width == 64 && TargetRange.Width == 32) 2556 return DiagnoseImpCast(S, E, T, diag::warn_impcast_integer_64_32); 2557 return DiagnoseImpCast(S, E, T, diag::warn_impcast_integer_precision); 2558 } 2559 2560 if ((TargetRange.NonNegative && !SourceRange.NonNegative) || 2561 (!TargetRange.NonNegative && SourceRange.NonNegative && 2562 SourceRange.Width == TargetRange.Width)) { 2563 unsigned DiagID = diag::warn_impcast_integer_sign; 2564 2565 // Traditionally, gcc has warned about this under -Wsign-compare. 2566 // We also want to warn about it in -Wconversion. 2567 // So if -Wconversion is off, use a completely identical diagnostic 2568 // in the sign-compare group. 2569 // The conditional-checking code will 2570 if (ICContext) { 2571 DiagID = diag::warn_impcast_integer_sign_conditional; 2572 *ICContext = true; 2573 } 2574 2575 return DiagnoseImpCast(S, E, T, DiagID); 2576 } 2577 2578 return; 2579} 2580 2581void CheckConditionalOperator(Sema &S, ConditionalOperator *E, QualType T); 2582 2583void CheckConditionalOperand(Sema &S, Expr *E, QualType T, 2584 bool &ICContext) { 2585 E = E->IgnoreParenImpCasts(); 2586 2587 if (isa<ConditionalOperator>(E)) 2588 return CheckConditionalOperator(S, cast<ConditionalOperator>(E), T); 2589 2590 AnalyzeImplicitConversions(S, E); 2591 if (E->getType() != T) 2592 return CheckImplicitConversion(S, E, T, &ICContext); 2593 return; 2594} 2595 2596void CheckConditionalOperator(Sema &S, ConditionalOperator *E, QualType T) { 2597 AnalyzeImplicitConversions(S, E->getCond()); 2598 2599 bool Suspicious = false; 2600 CheckConditionalOperand(S, E->getTrueExpr(), T, Suspicious); 2601 CheckConditionalOperand(S, E->getFalseExpr(), T, Suspicious); 2602 2603 // If -Wconversion would have warned about either of the candidates 2604 // for a signedness conversion to the context type... 2605 if (!Suspicious) return; 2606 2607 // ...but it's currently ignored... 2608 if (S.Diags.getDiagnosticLevel(diag::warn_impcast_integer_sign_conditional)) 2609 return; 2610 2611 // ...and -Wsign-compare isn't... 2612 if (!S.Diags.getDiagnosticLevel(diag::warn_mixed_sign_conditional)) 2613 return; 2614 2615 // ...then check whether it would have warned about either of the 2616 // candidates for a signedness conversion to the condition type. 2617 if (E->getType() != T) { 2618 Suspicious = false; 2619 CheckImplicitConversion(S, E->getTrueExpr()->IgnoreParenImpCasts(), 2620 E->getType(), &Suspicious); 2621 if (!Suspicious) 2622 CheckImplicitConversion(S, E->getFalseExpr()->IgnoreParenImpCasts(), 2623 E->getType(), &Suspicious); 2624 if (!Suspicious) 2625 return; 2626 } 2627 2628 // If so, emit a diagnostic under -Wsign-compare. 2629 Expr *lex = E->getTrueExpr()->IgnoreParenImpCasts(); 2630 Expr *rex = E->getFalseExpr()->IgnoreParenImpCasts(); 2631 S.Diag(E->getQuestionLoc(), diag::warn_mixed_sign_conditional) 2632 << lex->getType() << rex->getType() 2633 << lex->getSourceRange() << rex->getSourceRange(); 2634} 2635 2636/// AnalyzeImplicitConversions - Find and report any interesting 2637/// implicit conversions in the given expression. There are a couple 2638/// of competing diagnostics here, -Wconversion and -Wsign-compare. 2639void AnalyzeImplicitConversions(Sema &S, Expr *OrigE) { 2640 QualType T = OrigE->getType(); 2641 Expr *E = OrigE->IgnoreParenImpCasts(); 2642 2643 // For conditional operators, we analyze the arguments as if they 2644 // were being fed directly into the output. 2645 if (isa<ConditionalOperator>(E)) { 2646 ConditionalOperator *CO = cast<ConditionalOperator>(E); 2647 CheckConditionalOperator(S, CO, T); 2648 return; 2649 } 2650 2651 // Go ahead and check any implicit conversions we might have skipped. 2652 // The non-canonical typecheck is just an optimization; 2653 // CheckImplicitConversion will filter out dead implicit conversions. 2654 if (E->getType() != T) 2655 CheckImplicitConversion(S, E, T); 2656 2657 // Now continue drilling into this expression. 2658 2659 // Skip past explicit casts. 2660 if (isa<ExplicitCastExpr>(E)) { 2661 E = cast<ExplicitCastExpr>(E)->getSubExpr()->IgnoreParenImpCasts(); 2662 return AnalyzeImplicitConversions(S, E); 2663 } 2664 2665 // Do a somewhat different check with comparison operators. 2666 if (isa<BinaryOperator>(E) && cast<BinaryOperator>(E)->isComparisonOp()) 2667 return AnalyzeComparison(S, cast<BinaryOperator>(E)); 2668 2669 // These break the otherwise-useful invariant below. Fortunately, 2670 // we don't really need to recurse into them, because any internal 2671 // expressions should have been analyzed already when they were 2672 // built into statements. 2673 if (isa<StmtExpr>(E)) return; 2674 2675 // Don't descend into unevaluated contexts. 2676 if (isa<SizeOfAlignOfExpr>(E)) return; 2677 2678 // Now just recurse over the expression's children. 2679 for (Stmt::child_iterator I = E->child_begin(), IE = E->child_end(); 2680 I != IE; ++I) 2681 AnalyzeImplicitConversions(S, cast<Expr>(*I)); 2682} 2683 2684} // end anonymous namespace 2685 2686/// Diagnoses "dangerous" implicit conversions within the given 2687/// expression (which is a full expression). Implements -Wconversion 2688/// and -Wsign-compare. 2689void Sema::CheckImplicitConversions(Expr *E) { 2690 // Don't diagnose in unevaluated contexts. 2691 if (ExprEvalContexts.back().Context == Sema::Unevaluated) 2692 return; 2693 2694 // Don't diagnose for value- or type-dependent expressions. 2695 if (E->isTypeDependent() || E->isValueDependent()) 2696 return; 2697 2698 AnalyzeImplicitConversions(*this, E); 2699} 2700 2701/// CheckParmsForFunctionDef - Check that the parameters of the given 2702/// function are appropriate for the definition of a function. This 2703/// takes care of any checks that cannot be performed on the 2704/// declaration itself, e.g., that the types of each of the function 2705/// parameters are complete. 2706bool Sema::CheckParmsForFunctionDef(FunctionDecl *FD) { 2707 bool HasInvalidParm = false; 2708 for (unsigned p = 0, NumParams = FD->getNumParams(); p < NumParams; ++p) { 2709 ParmVarDecl *Param = FD->getParamDecl(p); 2710 2711 // C99 6.7.5.3p4: the parameters in a parameter type list in a 2712 // function declarator that is part of a function definition of 2713 // that function shall not have incomplete type. 2714 // 2715 // This is also C++ [dcl.fct]p6. 2716 if (!Param->isInvalidDecl() && 2717 RequireCompleteType(Param->getLocation(), Param->getType(), 2718 diag::err_typecheck_decl_incomplete_type)) { 2719 Param->setInvalidDecl(); 2720 HasInvalidParm = true; 2721 } 2722 2723 // C99 6.9.1p5: If the declarator includes a parameter type list, the 2724 // declaration of each parameter shall include an identifier. 2725 if (Param->getIdentifier() == 0 && 2726 !Param->isImplicit() && 2727 !getLangOptions().CPlusPlus) 2728 Diag(Param->getLocation(), diag::err_parameter_name_omitted); 2729 2730 // C99 6.7.5.3p12: 2731 // If the function declarator is not part of a definition of that 2732 // function, parameters may have incomplete type and may use the [*] 2733 // notation in their sequences of declarator specifiers to specify 2734 // variable length array types. 2735 QualType PType = Param->getOriginalType(); 2736 if (const ArrayType *AT = Context.getAsArrayType(PType)) { 2737 if (AT->getSizeModifier() == ArrayType::Star) { 2738 // FIXME: This diagnosic should point the the '[*]' if source-location 2739 // information is added for it. 2740 Diag(Param->getLocation(), diag::err_array_star_in_function_definition); 2741 } 2742 } 2743 } 2744 2745 return HasInvalidParm; 2746} 2747