SemaChecking.cpp revision 33e56f3273457bfa22c7c50bc46cf5a18216863d
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 "clang/Sema/Initialization.h" 16#include "clang/Sema/Sema.h" 17#include "clang/Sema/SemaInternal.h" 18#include "clang/Sema/ScopeInfo.h" 19#include "clang/Analysis/Analyses/FormatString.h" 20#include "clang/AST/ASTContext.h" 21#include "clang/AST/CharUnits.h" 22#include "clang/AST/DeclCXX.h" 23#include "clang/AST/DeclObjC.h" 24#include "clang/AST/ExprCXX.h" 25#include "clang/AST/ExprObjC.h" 26#include "clang/AST/EvaluatedExprVisitor.h" 27#include "clang/AST/DeclObjC.h" 28#include "clang/AST/StmtCXX.h" 29#include "clang/AST/StmtObjC.h" 30#include "clang/Lex/Preprocessor.h" 31#include "llvm/ADT/BitVector.h" 32#include "llvm/ADT/STLExtras.h" 33#include "llvm/Support/raw_ostream.h" 34#include "clang/Basic/TargetBuiltins.h" 35#include "clang/Basic/TargetInfo.h" 36#include "clang/Basic/ConvertUTF.h" 37#include <limits> 38using namespace clang; 39using namespace sema; 40 41SourceLocation Sema::getLocationOfStringLiteralByte(const StringLiteral *SL, 42 unsigned ByteNo) const { 43 return SL->getLocationOfByte(ByteNo, PP.getSourceManager(), 44 PP.getLangOptions(), PP.getTargetInfo()); 45} 46 47 48/// CheckablePrintfAttr - does a function call have a "printf" attribute 49/// and arguments that merit checking? 50bool Sema::CheckablePrintfAttr(const FormatAttr *Format, CallExpr *TheCall) { 51 if (Format->getType() == "printf") return true; 52 if (Format->getType() == "printf0") { 53 // printf0 allows null "format" string; if so don't check format/args 54 unsigned format_idx = Format->getFormatIdx() - 1; 55 // Does the index refer to the implicit object argument? 56 if (isa<CXXMemberCallExpr>(TheCall)) { 57 if (format_idx == 0) 58 return false; 59 --format_idx; 60 } 61 if (format_idx < TheCall->getNumArgs()) { 62 Expr *Format = TheCall->getArg(format_idx)->IgnoreParenCasts(); 63 if (!Format->isNullPointerConstant(Context, 64 Expr::NPC_ValueDependentIsNull)) 65 return true; 66 } 67 } 68 return false; 69} 70 71/// Checks that a call expression's argument count is the desired number. 72/// This is useful when doing custom type-checking. Returns true on error. 73static bool checkArgCount(Sema &S, CallExpr *call, unsigned desiredArgCount) { 74 unsigned argCount = call->getNumArgs(); 75 if (argCount == desiredArgCount) return false; 76 77 if (argCount < desiredArgCount) 78 return S.Diag(call->getLocEnd(), diag::err_typecheck_call_too_few_args) 79 << 0 /*function call*/ << desiredArgCount << argCount 80 << call->getSourceRange(); 81 82 // Highlight all the excess arguments. 83 SourceRange range(call->getArg(desiredArgCount)->getLocStart(), 84 call->getArg(argCount - 1)->getLocEnd()); 85 86 return S.Diag(range.getBegin(), diag::err_typecheck_call_too_many_args) 87 << 0 /*function call*/ << desiredArgCount << argCount 88 << call->getArg(1)->getSourceRange(); 89} 90 91/// CheckBuiltinAnnotationString - Checks that string argument to the builtin 92/// annotation is a non wide string literal. 93static bool CheckBuiltinAnnotationString(Sema &S, Expr *Arg) { 94 Arg = Arg->IgnoreParenCasts(); 95 StringLiteral *Literal = dyn_cast<StringLiteral>(Arg); 96 if (!Literal || !Literal->isAscii()) { 97 S.Diag(Arg->getLocStart(), diag::err_builtin_annotation_not_string_constant) 98 << Arg->getSourceRange(); 99 return true; 100 } 101 return false; 102} 103 104ExprResult 105Sema::CheckBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) { 106 ExprResult TheCallResult(Owned(TheCall)); 107 108 // Find out if any arguments are required to be integer constant expressions. 109 unsigned ICEArguments = 0; 110 ASTContext::GetBuiltinTypeError Error; 111 Context.GetBuiltinType(BuiltinID, Error, &ICEArguments); 112 if (Error != ASTContext::GE_None) 113 ICEArguments = 0; // Don't diagnose previously diagnosed errors. 114 115 // If any arguments are required to be ICE's, check and diagnose. 116 for (unsigned ArgNo = 0; ICEArguments != 0; ++ArgNo) { 117 // Skip arguments not required to be ICE's. 118 if ((ICEArguments & (1 << ArgNo)) == 0) continue; 119 120 llvm::APSInt Result; 121 if (SemaBuiltinConstantArg(TheCall, ArgNo, Result)) 122 return true; 123 ICEArguments &= ~(1 << ArgNo); 124 } 125 126 switch (BuiltinID) { 127 case Builtin::BI__builtin___CFStringMakeConstantString: 128 assert(TheCall->getNumArgs() == 1 && 129 "Wrong # arguments to builtin CFStringMakeConstantString"); 130 if (CheckObjCString(TheCall->getArg(0))) 131 return ExprError(); 132 break; 133 case Builtin::BI__builtin_stdarg_start: 134 case Builtin::BI__builtin_va_start: 135 if (SemaBuiltinVAStart(TheCall)) 136 return ExprError(); 137 break; 138 case Builtin::BI__builtin_isgreater: 139 case Builtin::BI__builtin_isgreaterequal: 140 case Builtin::BI__builtin_isless: 141 case Builtin::BI__builtin_islessequal: 142 case Builtin::BI__builtin_islessgreater: 143 case Builtin::BI__builtin_isunordered: 144 if (SemaBuiltinUnorderedCompare(TheCall)) 145 return ExprError(); 146 break; 147 case Builtin::BI__builtin_fpclassify: 148 if (SemaBuiltinFPClassification(TheCall, 6)) 149 return ExprError(); 150 break; 151 case Builtin::BI__builtin_isfinite: 152 case Builtin::BI__builtin_isinf: 153 case Builtin::BI__builtin_isinf_sign: 154 case Builtin::BI__builtin_isnan: 155 case Builtin::BI__builtin_isnormal: 156 if (SemaBuiltinFPClassification(TheCall, 1)) 157 return ExprError(); 158 break; 159 case Builtin::BI__builtin_shufflevector: 160 return SemaBuiltinShuffleVector(TheCall); 161 // TheCall will be freed by the smart pointer here, but that's fine, since 162 // SemaBuiltinShuffleVector guts it, but then doesn't release it. 163 case Builtin::BI__builtin_prefetch: 164 if (SemaBuiltinPrefetch(TheCall)) 165 return ExprError(); 166 break; 167 case Builtin::BI__builtin_object_size: 168 if (SemaBuiltinObjectSize(TheCall)) 169 return ExprError(); 170 break; 171 case Builtin::BI__builtin_longjmp: 172 if (SemaBuiltinLongjmp(TheCall)) 173 return ExprError(); 174 break; 175 176 case Builtin::BI__builtin_classify_type: 177 if (checkArgCount(*this, TheCall, 1)) return true; 178 TheCall->setType(Context.IntTy); 179 break; 180 case Builtin::BI__builtin_constant_p: 181 if (checkArgCount(*this, TheCall, 1)) return true; 182 TheCall->setType(Context.IntTy); 183 break; 184 case Builtin::BI__sync_fetch_and_add: 185 case Builtin::BI__sync_fetch_and_sub: 186 case Builtin::BI__sync_fetch_and_or: 187 case Builtin::BI__sync_fetch_and_and: 188 case Builtin::BI__sync_fetch_and_xor: 189 case Builtin::BI__sync_add_and_fetch: 190 case Builtin::BI__sync_sub_and_fetch: 191 case Builtin::BI__sync_and_and_fetch: 192 case Builtin::BI__sync_or_and_fetch: 193 case Builtin::BI__sync_xor_and_fetch: 194 case Builtin::BI__sync_val_compare_and_swap: 195 case Builtin::BI__sync_bool_compare_and_swap: 196 case Builtin::BI__sync_lock_test_and_set: 197 case Builtin::BI__sync_lock_release: 198 case Builtin::BI__sync_swap: 199 return SemaBuiltinAtomicOverloaded(move(TheCallResult)); 200 case Builtin::BI__builtin_annotation: 201 if (CheckBuiltinAnnotationString(*this, TheCall->getArg(1))) 202 return ExprError(); 203 break; 204 } 205 206 // Since the target specific builtins for each arch overlap, only check those 207 // of the arch we are compiling for. 208 if (BuiltinID >= Builtin::FirstTSBuiltin) { 209 switch (Context.getTargetInfo().getTriple().getArch()) { 210 case llvm::Triple::arm: 211 case llvm::Triple::thumb: 212 if (CheckARMBuiltinFunctionCall(BuiltinID, TheCall)) 213 return ExprError(); 214 break; 215 default: 216 break; 217 } 218 } 219 220 return move(TheCallResult); 221} 222 223// Get the valid immediate range for the specified NEON type code. 224static unsigned RFT(unsigned t, bool shift = false) { 225 bool quad = t & 0x10; 226 227 switch (t & 0x7) { 228 case 0: // i8 229 return shift ? 7 : (8 << (int)quad) - 1; 230 case 1: // i16 231 return shift ? 15 : (4 << (int)quad) - 1; 232 case 2: // i32 233 return shift ? 31 : (2 << (int)quad) - 1; 234 case 3: // i64 235 return shift ? 63 : (1 << (int)quad) - 1; 236 case 4: // f32 237 assert(!shift && "cannot shift float types!"); 238 return (2 << (int)quad) - 1; 239 case 5: // poly8 240 return shift ? 7 : (8 << (int)quad) - 1; 241 case 6: // poly16 242 return shift ? 15 : (4 << (int)quad) - 1; 243 case 7: // float16 244 assert(!shift && "cannot shift float types!"); 245 return (4 << (int)quad) - 1; 246 } 247 return 0; 248} 249 250bool Sema::CheckARMBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) { 251 llvm::APSInt Result; 252 253 unsigned mask = 0; 254 unsigned TV = 0; 255 switch (BuiltinID) { 256#define GET_NEON_OVERLOAD_CHECK 257#include "clang/Basic/arm_neon.inc" 258#undef GET_NEON_OVERLOAD_CHECK 259 } 260 261 // For NEON intrinsics which are overloaded on vector element type, validate 262 // the immediate which specifies which variant to emit. 263 if (mask) { 264 unsigned ArgNo = TheCall->getNumArgs()-1; 265 if (SemaBuiltinConstantArg(TheCall, ArgNo, Result)) 266 return true; 267 268 TV = Result.getLimitedValue(32); 269 if ((TV > 31) || (mask & (1 << TV)) == 0) 270 return Diag(TheCall->getLocStart(), diag::err_invalid_neon_type_code) 271 << TheCall->getArg(ArgNo)->getSourceRange(); 272 } 273 274 // For NEON intrinsics which take an immediate value as part of the 275 // instruction, range check them here. 276 unsigned i = 0, l = 0, u = 0; 277 switch (BuiltinID) { 278 default: return false; 279 case ARM::BI__builtin_arm_ssat: i = 1; l = 1; u = 31; break; 280 case ARM::BI__builtin_arm_usat: i = 1; u = 31; break; 281 case ARM::BI__builtin_arm_vcvtr_f: 282 case ARM::BI__builtin_arm_vcvtr_d: i = 1; u = 1; break; 283#define GET_NEON_IMMEDIATE_CHECK 284#include "clang/Basic/arm_neon.inc" 285#undef GET_NEON_IMMEDIATE_CHECK 286 }; 287 288 // Check that the immediate argument is actually a constant. 289 if (SemaBuiltinConstantArg(TheCall, i, Result)) 290 return true; 291 292 // Range check against the upper/lower values for this isntruction. 293 unsigned Val = Result.getZExtValue(); 294 if (Val < l || Val > (u + l)) 295 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 296 << l << u+l << TheCall->getArg(i)->getSourceRange(); 297 298 // FIXME: VFP Intrinsics should error if VFP not present. 299 return false; 300} 301 302/// CheckFunctionCall - Check a direct function call for various correctness 303/// and safety properties not strictly enforced by the C type system. 304bool Sema::CheckFunctionCall(FunctionDecl *FDecl, CallExpr *TheCall) { 305 // Get the IdentifierInfo* for the called function. 306 IdentifierInfo *FnInfo = FDecl->getIdentifier(); 307 308 // None of the checks below are needed for functions that don't have 309 // simple names (e.g., C++ conversion functions). 310 if (!FnInfo) 311 return false; 312 313 // FIXME: This mechanism should be abstracted to be less fragile and 314 // more efficient. For example, just map function ids to custom 315 // handlers. 316 317 // Printf and scanf checking. 318 for (specific_attr_iterator<FormatAttr> 319 i = FDecl->specific_attr_begin<FormatAttr>(), 320 e = FDecl->specific_attr_end<FormatAttr>(); i != e ; ++i) { 321 322 const FormatAttr *Format = *i; 323 const bool b = Format->getType() == "scanf"; 324 if (b || CheckablePrintfAttr(Format, TheCall)) { 325 bool HasVAListArg = Format->getFirstArg() == 0; 326 CheckPrintfScanfArguments(TheCall, HasVAListArg, 327 Format->getFormatIdx() - 1, 328 HasVAListArg ? 0 : Format->getFirstArg() - 1, 329 !b); 330 } 331 } 332 333 for (specific_attr_iterator<NonNullAttr> 334 i = FDecl->specific_attr_begin<NonNullAttr>(), 335 e = FDecl->specific_attr_end<NonNullAttr>(); i != e; ++i) { 336 CheckNonNullArguments(*i, TheCall->getArgs(), 337 TheCall->getCallee()->getLocStart()); 338 } 339 340 // Builtin handling 341 int CMF = -1; 342 switch (FDecl->getBuiltinID()) { 343 case Builtin::BI__builtin_memset: 344 case Builtin::BI__builtin___memset_chk: 345 case Builtin::BImemset: 346 CMF = CMF_Memset; 347 break; 348 349 case Builtin::BI__builtin_memcpy: 350 case Builtin::BI__builtin___memcpy_chk: 351 case Builtin::BImemcpy: 352 CMF = CMF_Memcpy; 353 break; 354 355 case Builtin::BI__builtin_memmove: 356 case Builtin::BI__builtin___memmove_chk: 357 case Builtin::BImemmove: 358 CMF = CMF_Memmove; 359 break; 360 361 case Builtin::BIstrlcpy: 362 case Builtin::BIstrlcat: 363 CheckStrlcpycatArguments(TheCall, FnInfo); 364 break; 365 366 case Builtin::BI__builtin_memcmp: 367 CMF = CMF_Memcmp; 368 break; 369 370 default: 371 if (FDecl->getLinkage() == ExternalLinkage && 372 (!getLangOptions().CPlusPlus || FDecl->isExternC())) { 373 if (FnInfo->isStr("memset")) 374 CMF = CMF_Memset; 375 else if (FnInfo->isStr("memcpy")) 376 CMF = CMF_Memcpy; 377 else if (FnInfo->isStr("memmove")) 378 CMF = CMF_Memmove; 379 else if (FnInfo->isStr("memcmp")) 380 CMF = CMF_Memcmp; 381 } 382 break; 383 } 384 385 // Memset/memcpy/memmove handling 386 if (CMF != -1) 387 CheckMemaccessArguments(TheCall, CheckedMemoryFunction(CMF), FnInfo); 388 389 return false; 390} 391 392bool Sema::CheckBlockCall(NamedDecl *NDecl, CallExpr *TheCall) { 393 // Printf checking. 394 const FormatAttr *Format = NDecl->getAttr<FormatAttr>(); 395 if (!Format) 396 return false; 397 398 const VarDecl *V = dyn_cast<VarDecl>(NDecl); 399 if (!V) 400 return false; 401 402 QualType Ty = V->getType(); 403 if (!Ty->isBlockPointerType()) 404 return false; 405 406 const bool b = Format->getType() == "scanf"; 407 if (!b && !CheckablePrintfAttr(Format, TheCall)) 408 return false; 409 410 bool HasVAListArg = Format->getFirstArg() == 0; 411 CheckPrintfScanfArguments(TheCall, HasVAListArg, Format->getFormatIdx() - 1, 412 HasVAListArg ? 0 : Format->getFirstArg() - 1, !b); 413 414 return false; 415} 416 417/// checkBuiltinArgument - Given a call to a builtin function, perform 418/// normal type-checking on the given argument, updating the call in 419/// place. This is useful when a builtin function requires custom 420/// type-checking for some of its arguments but not necessarily all of 421/// them. 422/// 423/// Returns true on error. 424static bool checkBuiltinArgument(Sema &S, CallExpr *E, unsigned ArgIndex) { 425 FunctionDecl *Fn = E->getDirectCallee(); 426 assert(Fn && "builtin call without direct callee!"); 427 428 ParmVarDecl *Param = Fn->getParamDecl(ArgIndex); 429 InitializedEntity Entity = 430 InitializedEntity::InitializeParameter(S.Context, Param); 431 432 ExprResult Arg = E->getArg(0); 433 Arg = S.PerformCopyInitialization(Entity, SourceLocation(), Arg); 434 if (Arg.isInvalid()) 435 return true; 436 437 E->setArg(ArgIndex, Arg.take()); 438 return false; 439} 440 441/// SemaBuiltinAtomicOverloaded - We have a call to a function like 442/// __sync_fetch_and_add, which is an overloaded function based on the pointer 443/// type of its first argument. The main ActOnCallExpr routines have already 444/// promoted the types of arguments because all of these calls are prototyped as 445/// void(...). 446/// 447/// This function goes through and does final semantic checking for these 448/// builtins, 449ExprResult 450Sema::SemaBuiltinAtomicOverloaded(ExprResult TheCallResult) { 451 CallExpr *TheCall = (CallExpr *)TheCallResult.get(); 452 DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts()); 453 FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl()); 454 455 // Ensure that we have at least one argument to do type inference from. 456 if (TheCall->getNumArgs() < 1) { 457 Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args_at_least) 458 << 0 << 1 << TheCall->getNumArgs() 459 << TheCall->getCallee()->getSourceRange(); 460 return ExprError(); 461 } 462 463 // Inspect the first argument of the atomic builtin. This should always be 464 // a pointer type, whose element is an integral scalar or pointer type. 465 // Because it is a pointer type, we don't have to worry about any implicit 466 // casts here. 467 // FIXME: We don't allow floating point scalars as input. 468 Expr *FirstArg = TheCall->getArg(0); 469 const PointerType *pointerType = FirstArg->getType()->getAs<PointerType>(); 470 if (!pointerType) { 471 Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer) 472 << FirstArg->getType() << FirstArg->getSourceRange(); 473 return ExprError(); 474 } 475 476 QualType ValType = pointerType->getPointeeType(); 477 if (!ValType->isIntegerType() && !ValType->isAnyPointerType() && 478 !ValType->isBlockPointerType()) { 479 Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer_intptr) 480 << FirstArg->getType() << FirstArg->getSourceRange(); 481 return ExprError(); 482 } 483 484 switch (ValType.getObjCLifetime()) { 485 case Qualifiers::OCL_None: 486 case Qualifiers::OCL_ExplicitNone: 487 // okay 488 break; 489 490 case Qualifiers::OCL_Weak: 491 case Qualifiers::OCL_Strong: 492 case Qualifiers::OCL_Autoreleasing: 493 Diag(DRE->getLocStart(), diag::err_arc_atomic_ownership) 494 << ValType << FirstArg->getSourceRange(); 495 return ExprError(); 496 } 497 498 // The majority of builtins return a value, but a few have special return 499 // types, so allow them to override appropriately below. 500 QualType ResultType = ValType; 501 502 // We need to figure out which concrete builtin this maps onto. For example, 503 // __sync_fetch_and_add with a 2 byte object turns into 504 // __sync_fetch_and_add_2. 505#define BUILTIN_ROW(x) \ 506 { Builtin::BI##x##_1, Builtin::BI##x##_2, Builtin::BI##x##_4, \ 507 Builtin::BI##x##_8, Builtin::BI##x##_16 } 508 509 static const unsigned BuiltinIndices[][5] = { 510 BUILTIN_ROW(__sync_fetch_and_add), 511 BUILTIN_ROW(__sync_fetch_and_sub), 512 BUILTIN_ROW(__sync_fetch_and_or), 513 BUILTIN_ROW(__sync_fetch_and_and), 514 BUILTIN_ROW(__sync_fetch_and_xor), 515 516 BUILTIN_ROW(__sync_add_and_fetch), 517 BUILTIN_ROW(__sync_sub_and_fetch), 518 BUILTIN_ROW(__sync_and_and_fetch), 519 BUILTIN_ROW(__sync_or_and_fetch), 520 BUILTIN_ROW(__sync_xor_and_fetch), 521 522 BUILTIN_ROW(__sync_val_compare_and_swap), 523 BUILTIN_ROW(__sync_bool_compare_and_swap), 524 BUILTIN_ROW(__sync_lock_test_and_set), 525 BUILTIN_ROW(__sync_lock_release), 526 BUILTIN_ROW(__sync_swap) 527 }; 528#undef BUILTIN_ROW 529 530 // Determine the index of the size. 531 unsigned SizeIndex; 532 switch (Context.getTypeSizeInChars(ValType).getQuantity()) { 533 case 1: SizeIndex = 0; break; 534 case 2: SizeIndex = 1; break; 535 case 4: SizeIndex = 2; break; 536 case 8: SizeIndex = 3; break; 537 case 16: SizeIndex = 4; break; 538 default: 539 Diag(DRE->getLocStart(), diag::err_atomic_builtin_pointer_size) 540 << FirstArg->getType() << FirstArg->getSourceRange(); 541 return ExprError(); 542 } 543 544 // Each of these builtins has one pointer argument, followed by some number of 545 // values (0, 1 or 2) followed by a potentially empty varags list of stuff 546 // that we ignore. Find out which row of BuiltinIndices to read from as well 547 // as the number of fixed args. 548 unsigned BuiltinID = FDecl->getBuiltinID(); 549 unsigned BuiltinIndex, NumFixed = 1; 550 switch (BuiltinID) { 551 default: assert(0 && "Unknown overloaded atomic builtin!"); 552 case Builtin::BI__sync_fetch_and_add: BuiltinIndex = 0; break; 553 case Builtin::BI__sync_fetch_and_sub: BuiltinIndex = 1; break; 554 case Builtin::BI__sync_fetch_and_or: BuiltinIndex = 2; break; 555 case Builtin::BI__sync_fetch_and_and: BuiltinIndex = 3; break; 556 case Builtin::BI__sync_fetch_and_xor: BuiltinIndex = 4; break; 557 558 case Builtin::BI__sync_add_and_fetch: BuiltinIndex = 5; break; 559 case Builtin::BI__sync_sub_and_fetch: BuiltinIndex = 6; break; 560 case Builtin::BI__sync_and_and_fetch: BuiltinIndex = 7; break; 561 case Builtin::BI__sync_or_and_fetch: BuiltinIndex = 8; break; 562 case Builtin::BI__sync_xor_and_fetch: BuiltinIndex = 9; break; 563 564 case Builtin::BI__sync_val_compare_and_swap: 565 BuiltinIndex = 10; 566 NumFixed = 2; 567 break; 568 case Builtin::BI__sync_bool_compare_and_swap: 569 BuiltinIndex = 11; 570 NumFixed = 2; 571 ResultType = Context.BoolTy; 572 break; 573 case Builtin::BI__sync_lock_test_and_set: BuiltinIndex = 12; break; 574 case Builtin::BI__sync_lock_release: 575 BuiltinIndex = 13; 576 NumFixed = 0; 577 ResultType = Context.VoidTy; 578 break; 579 case Builtin::BI__sync_swap: BuiltinIndex = 14; break; 580 } 581 582 // Now that we know how many fixed arguments we expect, first check that we 583 // have at least that many. 584 if (TheCall->getNumArgs() < 1+NumFixed) { 585 Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args_at_least) 586 << 0 << 1+NumFixed << TheCall->getNumArgs() 587 << TheCall->getCallee()->getSourceRange(); 588 return ExprError(); 589 } 590 591 // Get the decl for the concrete builtin from this, we can tell what the 592 // concrete integer type we should convert to is. 593 unsigned NewBuiltinID = BuiltinIndices[BuiltinIndex][SizeIndex]; 594 const char *NewBuiltinName = Context.BuiltinInfo.GetName(NewBuiltinID); 595 IdentifierInfo *NewBuiltinII = PP.getIdentifierInfo(NewBuiltinName); 596 FunctionDecl *NewBuiltinDecl = 597 cast<FunctionDecl>(LazilyCreateBuiltin(NewBuiltinII, NewBuiltinID, 598 TUScope, false, DRE->getLocStart())); 599 600 // The first argument --- the pointer --- has a fixed type; we 601 // deduce the types of the rest of the arguments accordingly. Walk 602 // the remaining arguments, converting them to the deduced value type. 603 for (unsigned i = 0; i != NumFixed; ++i) { 604 ExprResult Arg = TheCall->getArg(i+1); 605 606 // If the argument is an implicit cast, then there was a promotion due to 607 // "...", just remove it now. 608 if (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Arg.get())) { 609 Arg = ICE->getSubExpr(); 610 ICE->setSubExpr(0); 611 TheCall->setArg(i+1, Arg.get()); 612 } 613 614 // GCC does an implicit conversion to the pointer or integer ValType. This 615 // can fail in some cases (1i -> int**), check for this error case now. 616 CastKind Kind = CK_Invalid; 617 ExprValueKind VK = VK_RValue; 618 CXXCastPath BasePath; 619 Arg = CheckCastTypes(Arg.get()->getLocStart(), Arg.get()->getSourceRange(), 620 ValType, Arg.take(), Kind, VK, BasePath); 621 if (Arg.isInvalid()) 622 return ExprError(); 623 624 // Okay, we have something that *can* be converted to the right type. Check 625 // to see if there is a potentially weird extension going on here. This can 626 // happen when you do an atomic operation on something like an char* and 627 // pass in 42. The 42 gets converted to char. This is even more strange 628 // for things like 45.123 -> char, etc. 629 // FIXME: Do this check. 630 Arg = ImpCastExprToType(Arg.take(), ValType, Kind, VK, &BasePath); 631 TheCall->setArg(i+1, Arg.get()); 632 } 633 634 ASTContext& Context = this->getASTContext(); 635 636 // Create a new DeclRefExpr to refer to the new decl. 637 DeclRefExpr* NewDRE = DeclRefExpr::Create( 638 Context, 639 DRE->getQualifierLoc(), 640 NewBuiltinDecl, 641 DRE->getLocation(), 642 NewBuiltinDecl->getType(), 643 DRE->getValueKind()); 644 645 // Set the callee in the CallExpr. 646 // FIXME: This leaks the original parens and implicit casts. 647 ExprResult PromotedCall = UsualUnaryConversions(NewDRE); 648 if (PromotedCall.isInvalid()) 649 return ExprError(); 650 TheCall->setCallee(PromotedCall.take()); 651 652 // Change the result type of the call to match the original value type. This 653 // is arbitrary, but the codegen for these builtins ins design to handle it 654 // gracefully. 655 TheCall->setType(ResultType); 656 657 return move(TheCallResult); 658} 659 660/// CheckObjCString - Checks that the argument to the builtin 661/// CFString constructor is correct 662/// Note: It might also make sense to do the UTF-16 conversion here (would 663/// simplify the backend). 664bool Sema::CheckObjCString(Expr *Arg) { 665 Arg = Arg->IgnoreParenCasts(); 666 StringLiteral *Literal = dyn_cast<StringLiteral>(Arg); 667 668 if (!Literal || !Literal->isAscii()) { 669 Diag(Arg->getLocStart(), diag::err_cfstring_literal_not_string_constant) 670 << Arg->getSourceRange(); 671 return true; 672 } 673 674 if (Literal->containsNonAsciiOrNull()) { 675 StringRef String = Literal->getString(); 676 unsigned NumBytes = String.size(); 677 SmallVector<UTF16, 128> ToBuf(NumBytes); 678 const UTF8 *FromPtr = (UTF8 *)String.data(); 679 UTF16 *ToPtr = &ToBuf[0]; 680 681 ConversionResult Result = ConvertUTF8toUTF16(&FromPtr, FromPtr + NumBytes, 682 &ToPtr, ToPtr + NumBytes, 683 strictConversion); 684 // Check for conversion failure. 685 if (Result != conversionOK) 686 Diag(Arg->getLocStart(), 687 diag::warn_cfstring_truncated) << Arg->getSourceRange(); 688 } 689 return false; 690} 691 692/// SemaBuiltinVAStart - Check the arguments to __builtin_va_start for validity. 693/// Emit an error and return true on failure, return false on success. 694bool Sema::SemaBuiltinVAStart(CallExpr *TheCall) { 695 Expr *Fn = TheCall->getCallee(); 696 if (TheCall->getNumArgs() > 2) { 697 Diag(TheCall->getArg(2)->getLocStart(), 698 diag::err_typecheck_call_too_many_args) 699 << 0 /*function call*/ << 2 << TheCall->getNumArgs() 700 << Fn->getSourceRange() 701 << SourceRange(TheCall->getArg(2)->getLocStart(), 702 (*(TheCall->arg_end()-1))->getLocEnd()); 703 return true; 704 } 705 706 if (TheCall->getNumArgs() < 2) { 707 return Diag(TheCall->getLocEnd(), 708 diag::err_typecheck_call_too_few_args_at_least) 709 << 0 /*function call*/ << 2 << TheCall->getNumArgs(); 710 } 711 712 // Type-check the first argument normally. 713 if (checkBuiltinArgument(*this, TheCall, 0)) 714 return true; 715 716 // Determine whether the current function is variadic or not. 717 BlockScopeInfo *CurBlock = getCurBlock(); 718 bool isVariadic; 719 if (CurBlock) 720 isVariadic = CurBlock->TheDecl->isVariadic(); 721 else if (FunctionDecl *FD = getCurFunctionDecl()) 722 isVariadic = FD->isVariadic(); 723 else 724 isVariadic = getCurMethodDecl()->isVariadic(); 725 726 if (!isVariadic) { 727 Diag(Fn->getLocStart(), diag::err_va_start_used_in_non_variadic_function); 728 return true; 729 } 730 731 // Verify that the second argument to the builtin is the last argument of the 732 // current function or method. 733 bool SecondArgIsLastNamedArgument = false; 734 const Expr *Arg = TheCall->getArg(1)->IgnoreParenCasts(); 735 736 if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Arg)) { 737 if (const ParmVarDecl *PV = dyn_cast<ParmVarDecl>(DR->getDecl())) { 738 // FIXME: This isn't correct for methods (results in bogus warning). 739 // Get the last formal in the current function. 740 const ParmVarDecl *LastArg; 741 if (CurBlock) 742 LastArg = *(CurBlock->TheDecl->param_end()-1); 743 else if (FunctionDecl *FD = getCurFunctionDecl()) 744 LastArg = *(FD->param_end()-1); 745 else 746 LastArg = *(getCurMethodDecl()->param_end()-1); 747 SecondArgIsLastNamedArgument = PV == LastArg; 748 } 749 } 750 751 if (!SecondArgIsLastNamedArgument) 752 Diag(TheCall->getArg(1)->getLocStart(), 753 diag::warn_second_parameter_of_va_start_not_last_named_argument); 754 return false; 755} 756 757/// SemaBuiltinUnorderedCompare - Handle functions like __builtin_isgreater and 758/// friends. This is declared to take (...), so we have to check everything. 759bool Sema::SemaBuiltinUnorderedCompare(CallExpr *TheCall) { 760 if (TheCall->getNumArgs() < 2) 761 return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args) 762 << 0 << 2 << TheCall->getNumArgs()/*function call*/; 763 if (TheCall->getNumArgs() > 2) 764 return Diag(TheCall->getArg(2)->getLocStart(), 765 diag::err_typecheck_call_too_many_args) 766 << 0 /*function call*/ << 2 << TheCall->getNumArgs() 767 << SourceRange(TheCall->getArg(2)->getLocStart(), 768 (*(TheCall->arg_end()-1))->getLocEnd()); 769 770 ExprResult OrigArg0 = TheCall->getArg(0); 771 ExprResult OrigArg1 = TheCall->getArg(1); 772 773 // Do standard promotions between the two arguments, returning their common 774 // type. 775 QualType Res = UsualArithmeticConversions(OrigArg0, OrigArg1, false); 776 if (OrigArg0.isInvalid() || OrigArg1.isInvalid()) 777 return true; 778 779 // Make sure any conversions are pushed back into the call; this is 780 // type safe since unordered compare builtins are declared as "_Bool 781 // foo(...)". 782 TheCall->setArg(0, OrigArg0.get()); 783 TheCall->setArg(1, OrigArg1.get()); 784 785 if (OrigArg0.get()->isTypeDependent() || OrigArg1.get()->isTypeDependent()) 786 return false; 787 788 // If the common type isn't a real floating type, then the arguments were 789 // invalid for this operation. 790 if (!Res->isRealFloatingType()) 791 return Diag(OrigArg0.get()->getLocStart(), 792 diag::err_typecheck_call_invalid_ordered_compare) 793 << OrigArg0.get()->getType() << OrigArg1.get()->getType() 794 << SourceRange(OrigArg0.get()->getLocStart(), OrigArg1.get()->getLocEnd()); 795 796 return false; 797} 798 799/// SemaBuiltinSemaBuiltinFPClassification - Handle functions like 800/// __builtin_isnan and friends. This is declared to take (...), so we have 801/// to check everything. We expect the last argument to be a floating point 802/// value. 803bool Sema::SemaBuiltinFPClassification(CallExpr *TheCall, unsigned NumArgs) { 804 if (TheCall->getNumArgs() < NumArgs) 805 return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args) 806 << 0 << NumArgs << TheCall->getNumArgs()/*function call*/; 807 if (TheCall->getNumArgs() > NumArgs) 808 return Diag(TheCall->getArg(NumArgs)->getLocStart(), 809 diag::err_typecheck_call_too_many_args) 810 << 0 /*function call*/ << NumArgs << TheCall->getNumArgs() 811 << SourceRange(TheCall->getArg(NumArgs)->getLocStart(), 812 (*(TheCall->arg_end()-1))->getLocEnd()); 813 814 Expr *OrigArg = TheCall->getArg(NumArgs-1); 815 816 if (OrigArg->isTypeDependent()) 817 return false; 818 819 // This operation requires a non-_Complex floating-point number. 820 if (!OrigArg->getType()->isRealFloatingType()) 821 return Diag(OrigArg->getLocStart(), 822 diag::err_typecheck_call_invalid_unary_fp) 823 << OrigArg->getType() << OrigArg->getSourceRange(); 824 825 // If this is an implicit conversion from float -> double, remove it. 826 if (ImplicitCastExpr *Cast = dyn_cast<ImplicitCastExpr>(OrigArg)) { 827 Expr *CastArg = Cast->getSubExpr(); 828 if (CastArg->getType()->isSpecificBuiltinType(BuiltinType::Float)) { 829 assert(Cast->getType()->isSpecificBuiltinType(BuiltinType::Double) && 830 "promotion from float to double is the only expected cast here"); 831 Cast->setSubExpr(0); 832 TheCall->setArg(NumArgs-1, CastArg); 833 OrigArg = CastArg; 834 } 835 } 836 837 return false; 838} 839 840/// SemaBuiltinShuffleVector - Handle __builtin_shufflevector. 841// This is declared to take (...), so we have to check everything. 842ExprResult Sema::SemaBuiltinShuffleVector(CallExpr *TheCall) { 843 if (TheCall->getNumArgs() < 2) 844 return ExprError(Diag(TheCall->getLocEnd(), 845 diag::err_typecheck_call_too_few_args_at_least) 846 << 0 /*function call*/ << 2 << TheCall->getNumArgs() 847 << TheCall->getSourceRange()); 848 849 // Determine which of the following types of shufflevector we're checking: 850 // 1) unary, vector mask: (lhs, mask) 851 // 2) binary, vector mask: (lhs, rhs, mask) 852 // 3) binary, scalar mask: (lhs, rhs, index, ..., index) 853 QualType resType = TheCall->getArg(0)->getType(); 854 unsigned numElements = 0; 855 856 if (!TheCall->getArg(0)->isTypeDependent() && 857 !TheCall->getArg(1)->isTypeDependent()) { 858 QualType LHSType = TheCall->getArg(0)->getType(); 859 QualType RHSType = TheCall->getArg(1)->getType(); 860 861 if (!LHSType->isVectorType() || !RHSType->isVectorType()) { 862 Diag(TheCall->getLocStart(), diag::err_shufflevector_non_vector) 863 << SourceRange(TheCall->getArg(0)->getLocStart(), 864 TheCall->getArg(1)->getLocEnd()); 865 return ExprError(); 866 } 867 868 numElements = LHSType->getAs<VectorType>()->getNumElements(); 869 unsigned numResElements = TheCall->getNumArgs() - 2; 870 871 // Check to see if we have a call with 2 vector arguments, the unary shuffle 872 // with mask. If so, verify that RHS is an integer vector type with the 873 // same number of elts as lhs. 874 if (TheCall->getNumArgs() == 2) { 875 if (!RHSType->hasIntegerRepresentation() || 876 RHSType->getAs<VectorType>()->getNumElements() != numElements) 877 Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector) 878 << SourceRange(TheCall->getArg(1)->getLocStart(), 879 TheCall->getArg(1)->getLocEnd()); 880 numResElements = numElements; 881 } 882 else if (!Context.hasSameUnqualifiedType(LHSType, RHSType)) { 883 Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector) 884 << SourceRange(TheCall->getArg(0)->getLocStart(), 885 TheCall->getArg(1)->getLocEnd()); 886 return ExprError(); 887 } else if (numElements != numResElements) { 888 QualType eltType = LHSType->getAs<VectorType>()->getElementType(); 889 resType = Context.getVectorType(eltType, numResElements, 890 VectorType::GenericVector); 891 } 892 } 893 894 for (unsigned i = 2; i < TheCall->getNumArgs(); i++) { 895 if (TheCall->getArg(i)->isTypeDependent() || 896 TheCall->getArg(i)->isValueDependent()) 897 continue; 898 899 llvm::APSInt Result(32); 900 if (!TheCall->getArg(i)->isIntegerConstantExpr(Result, Context)) 901 return ExprError(Diag(TheCall->getLocStart(), 902 diag::err_shufflevector_nonconstant_argument) 903 << TheCall->getArg(i)->getSourceRange()); 904 905 if (Result.getActiveBits() > 64 || Result.getZExtValue() >= numElements*2) 906 return ExprError(Diag(TheCall->getLocStart(), 907 diag::err_shufflevector_argument_too_large) 908 << TheCall->getArg(i)->getSourceRange()); 909 } 910 911 SmallVector<Expr*, 32> exprs; 912 913 for (unsigned i = 0, e = TheCall->getNumArgs(); i != e; i++) { 914 exprs.push_back(TheCall->getArg(i)); 915 TheCall->setArg(i, 0); 916 } 917 918 return Owned(new (Context) ShuffleVectorExpr(Context, exprs.begin(), 919 exprs.size(), resType, 920 TheCall->getCallee()->getLocStart(), 921 TheCall->getRParenLoc())); 922} 923 924/// SemaBuiltinPrefetch - Handle __builtin_prefetch. 925// This is declared to take (const void*, ...) and can take two 926// optional constant int args. 927bool Sema::SemaBuiltinPrefetch(CallExpr *TheCall) { 928 unsigned NumArgs = TheCall->getNumArgs(); 929 930 if (NumArgs > 3) 931 return Diag(TheCall->getLocEnd(), 932 diag::err_typecheck_call_too_many_args_at_most) 933 << 0 /*function call*/ << 3 << NumArgs 934 << TheCall->getSourceRange(); 935 936 // Argument 0 is checked for us and the remaining arguments must be 937 // constant integers. 938 for (unsigned i = 1; i != NumArgs; ++i) { 939 Expr *Arg = TheCall->getArg(i); 940 941 llvm::APSInt Result; 942 if (SemaBuiltinConstantArg(TheCall, i, Result)) 943 return true; 944 945 // FIXME: gcc issues a warning and rewrites these to 0. These 946 // seems especially odd for the third argument since the default 947 // is 3. 948 if (i == 1) { 949 if (Result.getLimitedValue() > 1) 950 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 951 << "0" << "1" << Arg->getSourceRange(); 952 } else { 953 if (Result.getLimitedValue() > 3) 954 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 955 << "0" << "3" << Arg->getSourceRange(); 956 } 957 } 958 959 return false; 960} 961 962/// SemaBuiltinConstantArg - Handle a check if argument ArgNum of CallExpr 963/// TheCall is a constant expression. 964bool Sema::SemaBuiltinConstantArg(CallExpr *TheCall, int ArgNum, 965 llvm::APSInt &Result) { 966 Expr *Arg = TheCall->getArg(ArgNum); 967 DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts()); 968 FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl()); 969 970 if (Arg->isTypeDependent() || Arg->isValueDependent()) return false; 971 972 if (!Arg->isIntegerConstantExpr(Result, Context)) 973 return Diag(TheCall->getLocStart(), diag::err_constant_integer_arg_type) 974 << FDecl->getDeclName() << Arg->getSourceRange(); 975 976 return false; 977} 978 979/// SemaBuiltinObjectSize - Handle __builtin_object_size(void *ptr, 980/// int type). This simply type checks that type is one of the defined 981/// constants (0-3). 982// For compatibility check 0-3, llvm only handles 0 and 2. 983bool Sema::SemaBuiltinObjectSize(CallExpr *TheCall) { 984 llvm::APSInt Result; 985 986 // Check constant-ness first. 987 if (SemaBuiltinConstantArg(TheCall, 1, Result)) 988 return true; 989 990 Expr *Arg = TheCall->getArg(1); 991 if (Result.getSExtValue() < 0 || Result.getSExtValue() > 3) { 992 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 993 << "0" << "3" << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); 994 } 995 996 return false; 997} 998 999/// SemaBuiltinLongjmp - Handle __builtin_longjmp(void *env[5], int val). 1000/// This checks that val is a constant 1. 1001bool Sema::SemaBuiltinLongjmp(CallExpr *TheCall) { 1002 Expr *Arg = TheCall->getArg(1); 1003 llvm::APSInt Result; 1004 1005 // TODO: This is less than ideal. Overload this to take a value. 1006 if (SemaBuiltinConstantArg(TheCall, 1, Result)) 1007 return true; 1008 1009 if (Result != 1) 1010 return Diag(TheCall->getLocStart(), diag::err_builtin_longjmp_invalid_val) 1011 << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); 1012 1013 return false; 1014} 1015 1016// Handle i > 1 ? "x" : "y", recursively. 1017bool Sema::SemaCheckStringLiteral(const Expr *E, const CallExpr *TheCall, 1018 bool HasVAListArg, 1019 unsigned format_idx, unsigned firstDataArg, 1020 bool isPrintf) { 1021 tryAgain: 1022 if (E->isTypeDependent() || E->isValueDependent()) 1023 return false; 1024 1025 E = E->IgnoreParens(); 1026 1027 switch (E->getStmtClass()) { 1028 case Stmt::BinaryConditionalOperatorClass: 1029 case Stmt::ConditionalOperatorClass: { 1030 const AbstractConditionalOperator *C = cast<AbstractConditionalOperator>(E); 1031 return SemaCheckStringLiteral(C->getTrueExpr(), TheCall, HasVAListArg, 1032 format_idx, firstDataArg, isPrintf) 1033 && SemaCheckStringLiteral(C->getFalseExpr(), TheCall, HasVAListArg, 1034 format_idx, firstDataArg, isPrintf); 1035 } 1036 1037 case Stmt::IntegerLiteralClass: 1038 // Technically -Wformat-nonliteral does not warn about this case. 1039 // The behavior of printf and friends in this case is implementation 1040 // dependent. Ideally if the format string cannot be null then 1041 // it should have a 'nonnull' attribute in the function prototype. 1042 return true; 1043 1044 case Stmt::ImplicitCastExprClass: { 1045 E = cast<ImplicitCastExpr>(E)->getSubExpr(); 1046 goto tryAgain; 1047 } 1048 1049 case Stmt::OpaqueValueExprClass: 1050 if (const Expr *src = cast<OpaqueValueExpr>(E)->getSourceExpr()) { 1051 E = src; 1052 goto tryAgain; 1053 } 1054 return false; 1055 1056 case Stmt::PredefinedExprClass: 1057 // While __func__, etc., are technically not string literals, they 1058 // cannot contain format specifiers and thus are not a security 1059 // liability. 1060 return true; 1061 1062 case Stmt::DeclRefExprClass: { 1063 const DeclRefExpr *DR = cast<DeclRefExpr>(E); 1064 1065 // As an exception, do not flag errors for variables binding to 1066 // const string literals. 1067 if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) { 1068 bool isConstant = false; 1069 QualType T = DR->getType(); 1070 1071 if (const ArrayType *AT = Context.getAsArrayType(T)) { 1072 isConstant = AT->getElementType().isConstant(Context); 1073 } else if (const PointerType *PT = T->getAs<PointerType>()) { 1074 isConstant = T.isConstant(Context) && 1075 PT->getPointeeType().isConstant(Context); 1076 } 1077 1078 if (isConstant) { 1079 if (const Expr *Init = VD->getAnyInitializer()) 1080 return SemaCheckStringLiteral(Init, TheCall, 1081 HasVAListArg, format_idx, firstDataArg, 1082 isPrintf); 1083 } 1084 1085 // For vprintf* functions (i.e., HasVAListArg==true), we add a 1086 // special check to see if the format string is a function parameter 1087 // of the function calling the printf function. If the function 1088 // has an attribute indicating it is a printf-like function, then we 1089 // should suppress warnings concerning non-literals being used in a call 1090 // to a vprintf function. For example: 1091 // 1092 // void 1093 // logmessage(char const *fmt __attribute__ (format (printf, 1, 2)), ...){ 1094 // va_list ap; 1095 // va_start(ap, fmt); 1096 // vprintf(fmt, ap); // Do NOT emit a warning about "fmt". 1097 // ... 1098 // 1099 // 1100 // FIXME: We don't have full attribute support yet, so just check to see 1101 // if the argument is a DeclRefExpr that references a parameter. We'll 1102 // add proper support for checking the attribute later. 1103 if (HasVAListArg) 1104 if (isa<ParmVarDecl>(VD)) 1105 return true; 1106 } 1107 1108 return false; 1109 } 1110 1111 case Stmt::CallExprClass: { 1112 const CallExpr *CE = cast<CallExpr>(E); 1113 if (const ImplicitCastExpr *ICE 1114 = dyn_cast<ImplicitCastExpr>(CE->getCallee())) { 1115 if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(ICE->getSubExpr())) { 1116 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(DRE->getDecl())) { 1117 if (const FormatArgAttr *FA = FD->getAttr<FormatArgAttr>()) { 1118 unsigned ArgIndex = FA->getFormatIdx(); 1119 const Expr *Arg = CE->getArg(ArgIndex - 1); 1120 1121 return SemaCheckStringLiteral(Arg, TheCall, HasVAListArg, 1122 format_idx, firstDataArg, isPrintf); 1123 } 1124 } 1125 } 1126 } 1127 1128 return false; 1129 } 1130 case Stmt::ObjCStringLiteralClass: 1131 case Stmt::StringLiteralClass: { 1132 const StringLiteral *StrE = NULL; 1133 1134 if (const ObjCStringLiteral *ObjCFExpr = dyn_cast<ObjCStringLiteral>(E)) 1135 StrE = ObjCFExpr->getString(); 1136 else 1137 StrE = cast<StringLiteral>(E); 1138 1139 if (StrE) { 1140 CheckFormatString(StrE, E, TheCall, HasVAListArg, format_idx, 1141 firstDataArg, isPrintf); 1142 return true; 1143 } 1144 1145 return false; 1146 } 1147 1148 default: 1149 return false; 1150 } 1151} 1152 1153void 1154Sema::CheckNonNullArguments(const NonNullAttr *NonNull, 1155 const Expr * const *ExprArgs, 1156 SourceLocation CallSiteLoc) { 1157 for (NonNullAttr::args_iterator i = NonNull->args_begin(), 1158 e = NonNull->args_end(); 1159 i != e; ++i) { 1160 const Expr *ArgExpr = ExprArgs[*i]; 1161 if (ArgExpr->isNullPointerConstant(Context, 1162 Expr::NPC_ValueDependentIsNotNull)) 1163 Diag(CallSiteLoc, diag::warn_null_arg) << ArgExpr->getSourceRange(); 1164 } 1165} 1166 1167/// CheckPrintfScanfArguments - Check calls to printf and scanf (and similar 1168/// functions) for correct use of format strings. 1169void 1170Sema::CheckPrintfScanfArguments(const CallExpr *TheCall, bool HasVAListArg, 1171 unsigned format_idx, unsigned firstDataArg, 1172 bool isPrintf) { 1173 1174 const Expr *Fn = TheCall->getCallee(); 1175 1176 // The way the format attribute works in GCC, the implicit this argument 1177 // of member functions is counted. However, it doesn't appear in our own 1178 // lists, so decrement format_idx in that case. 1179 if (isa<CXXMemberCallExpr>(TheCall)) { 1180 const CXXMethodDecl *method_decl = 1181 dyn_cast<CXXMethodDecl>(TheCall->getCalleeDecl()); 1182 if (method_decl && method_decl->isInstance()) { 1183 // Catch a format attribute mistakenly referring to the object argument. 1184 if (format_idx == 0) 1185 return; 1186 --format_idx; 1187 if(firstDataArg != 0) 1188 --firstDataArg; 1189 } 1190 } 1191 1192 // CHECK: printf/scanf-like function is called with no format string. 1193 if (format_idx >= TheCall->getNumArgs()) { 1194 Diag(TheCall->getRParenLoc(), diag::warn_missing_format_string) 1195 << Fn->getSourceRange(); 1196 return; 1197 } 1198 1199 const Expr *OrigFormatExpr = TheCall->getArg(format_idx)->IgnoreParenCasts(); 1200 1201 // CHECK: format string is not a string literal. 1202 // 1203 // Dynamically generated format strings are difficult to 1204 // automatically vet at compile time. Requiring that format strings 1205 // are string literals: (1) permits the checking of format strings by 1206 // the compiler and thereby (2) can practically remove the source of 1207 // many format string exploits. 1208 1209 // Format string can be either ObjC string (e.g. @"%d") or 1210 // C string (e.g. "%d") 1211 // ObjC string uses the same format specifiers as C string, so we can use 1212 // the same format string checking logic for both ObjC and C strings. 1213 if (SemaCheckStringLiteral(OrigFormatExpr, TheCall, HasVAListArg, format_idx, 1214 firstDataArg, isPrintf)) 1215 return; // Literal format string found, check done! 1216 1217 // If there are no arguments specified, warn with -Wformat-security, otherwise 1218 // warn only with -Wformat-nonliteral. 1219 if (TheCall->getNumArgs() == format_idx+1) 1220 Diag(TheCall->getArg(format_idx)->getLocStart(), 1221 diag::warn_format_nonliteral_noargs) 1222 << OrigFormatExpr->getSourceRange(); 1223 else 1224 Diag(TheCall->getArg(format_idx)->getLocStart(), 1225 diag::warn_format_nonliteral) 1226 << OrigFormatExpr->getSourceRange(); 1227} 1228 1229namespace { 1230class CheckFormatHandler : public analyze_format_string::FormatStringHandler { 1231protected: 1232 Sema &S; 1233 const StringLiteral *FExpr; 1234 const Expr *OrigFormatExpr; 1235 const unsigned FirstDataArg; 1236 const unsigned NumDataArgs; 1237 const bool IsObjCLiteral; 1238 const char *Beg; // Start of format string. 1239 const bool HasVAListArg; 1240 const CallExpr *TheCall; 1241 unsigned FormatIdx; 1242 llvm::BitVector CoveredArgs; 1243 bool usesPositionalArgs; 1244 bool atFirstArg; 1245public: 1246 CheckFormatHandler(Sema &s, const StringLiteral *fexpr, 1247 const Expr *origFormatExpr, unsigned firstDataArg, 1248 unsigned numDataArgs, bool isObjCLiteral, 1249 const char *beg, bool hasVAListArg, 1250 const CallExpr *theCall, unsigned formatIdx) 1251 : S(s), FExpr(fexpr), OrigFormatExpr(origFormatExpr), 1252 FirstDataArg(firstDataArg), 1253 NumDataArgs(numDataArgs), 1254 IsObjCLiteral(isObjCLiteral), Beg(beg), 1255 HasVAListArg(hasVAListArg), 1256 TheCall(theCall), FormatIdx(formatIdx), 1257 usesPositionalArgs(false), atFirstArg(true) { 1258 CoveredArgs.resize(numDataArgs); 1259 CoveredArgs.reset(); 1260 } 1261 1262 void DoneProcessing(); 1263 1264 void HandleIncompleteSpecifier(const char *startSpecifier, 1265 unsigned specifierLen); 1266 1267 virtual void HandleInvalidPosition(const char *startSpecifier, 1268 unsigned specifierLen, 1269 analyze_format_string::PositionContext p); 1270 1271 virtual void HandleZeroPosition(const char *startPos, unsigned posLen); 1272 1273 void HandleNullChar(const char *nullCharacter); 1274 1275protected: 1276 bool HandleInvalidConversionSpecifier(unsigned argIndex, SourceLocation Loc, 1277 const char *startSpec, 1278 unsigned specifierLen, 1279 const char *csStart, unsigned csLen); 1280 1281 SourceRange getFormatStringRange(); 1282 CharSourceRange getSpecifierRange(const char *startSpecifier, 1283 unsigned specifierLen); 1284 SourceLocation getLocationOfByte(const char *x); 1285 1286 const Expr *getDataArg(unsigned i) const; 1287 1288 bool CheckNumArgs(const analyze_format_string::FormatSpecifier &FS, 1289 const analyze_format_string::ConversionSpecifier &CS, 1290 const char *startSpecifier, unsigned specifierLen, 1291 unsigned argIndex); 1292}; 1293} 1294 1295SourceRange CheckFormatHandler::getFormatStringRange() { 1296 return OrigFormatExpr->getSourceRange(); 1297} 1298 1299CharSourceRange CheckFormatHandler:: 1300getSpecifierRange(const char *startSpecifier, unsigned specifierLen) { 1301 SourceLocation Start = getLocationOfByte(startSpecifier); 1302 SourceLocation End = getLocationOfByte(startSpecifier + specifierLen - 1); 1303 1304 // Advance the end SourceLocation by one due to half-open ranges. 1305 End = End.getFileLocWithOffset(1); 1306 1307 return CharSourceRange::getCharRange(Start, End); 1308} 1309 1310SourceLocation CheckFormatHandler::getLocationOfByte(const char *x) { 1311 return S.getLocationOfStringLiteralByte(FExpr, x - Beg); 1312} 1313 1314void CheckFormatHandler::HandleIncompleteSpecifier(const char *startSpecifier, 1315 unsigned specifierLen){ 1316 SourceLocation Loc = getLocationOfByte(startSpecifier); 1317 S.Diag(Loc, diag::warn_printf_incomplete_specifier) 1318 << getSpecifierRange(startSpecifier, specifierLen); 1319} 1320 1321void 1322CheckFormatHandler::HandleInvalidPosition(const char *startPos, unsigned posLen, 1323 analyze_format_string::PositionContext p) { 1324 SourceLocation Loc = getLocationOfByte(startPos); 1325 S.Diag(Loc, diag::warn_format_invalid_positional_specifier) 1326 << (unsigned) p << getSpecifierRange(startPos, posLen); 1327} 1328 1329void CheckFormatHandler::HandleZeroPosition(const char *startPos, 1330 unsigned posLen) { 1331 SourceLocation Loc = getLocationOfByte(startPos); 1332 S.Diag(Loc, diag::warn_format_zero_positional_specifier) 1333 << getSpecifierRange(startPos, posLen); 1334} 1335 1336void CheckFormatHandler::HandleNullChar(const char *nullCharacter) { 1337 if (!IsObjCLiteral) { 1338 // The presence of a null character is likely an error. 1339 S.Diag(getLocationOfByte(nullCharacter), 1340 diag::warn_printf_format_string_contains_null_char) 1341 << getFormatStringRange(); 1342 } 1343} 1344 1345const Expr *CheckFormatHandler::getDataArg(unsigned i) const { 1346 return TheCall->getArg(FirstDataArg + i); 1347} 1348 1349void CheckFormatHandler::DoneProcessing() { 1350 // Does the number of data arguments exceed the number of 1351 // format conversions in the format string? 1352 if (!HasVAListArg) { 1353 // Find any arguments that weren't covered. 1354 CoveredArgs.flip(); 1355 signed notCoveredArg = CoveredArgs.find_first(); 1356 if (notCoveredArg >= 0) { 1357 assert((unsigned)notCoveredArg < NumDataArgs); 1358 S.Diag(getDataArg((unsigned) notCoveredArg)->getLocStart(), 1359 diag::warn_printf_data_arg_not_used) 1360 << getFormatStringRange(); 1361 } 1362 } 1363} 1364 1365bool 1366CheckFormatHandler::HandleInvalidConversionSpecifier(unsigned argIndex, 1367 SourceLocation Loc, 1368 const char *startSpec, 1369 unsigned specifierLen, 1370 const char *csStart, 1371 unsigned csLen) { 1372 1373 bool keepGoing = true; 1374 if (argIndex < NumDataArgs) { 1375 // Consider the argument coverered, even though the specifier doesn't 1376 // make sense. 1377 CoveredArgs.set(argIndex); 1378 } 1379 else { 1380 // If argIndex exceeds the number of data arguments we 1381 // don't issue a warning because that is just a cascade of warnings (and 1382 // they may have intended '%%' anyway). We don't want to continue processing 1383 // the format string after this point, however, as we will like just get 1384 // gibberish when trying to match arguments. 1385 keepGoing = false; 1386 } 1387 1388 S.Diag(Loc, diag::warn_format_invalid_conversion) 1389 << StringRef(csStart, csLen) 1390 << getSpecifierRange(startSpec, specifierLen); 1391 1392 return keepGoing; 1393} 1394 1395bool 1396CheckFormatHandler::CheckNumArgs( 1397 const analyze_format_string::FormatSpecifier &FS, 1398 const analyze_format_string::ConversionSpecifier &CS, 1399 const char *startSpecifier, unsigned specifierLen, unsigned argIndex) { 1400 1401 if (argIndex >= NumDataArgs) { 1402 if (FS.usesPositionalArg()) { 1403 S.Diag(getLocationOfByte(CS.getStart()), 1404 diag::warn_printf_positional_arg_exceeds_data_args) 1405 << (argIndex+1) << NumDataArgs 1406 << getSpecifierRange(startSpecifier, specifierLen); 1407 } 1408 else { 1409 S.Diag(getLocationOfByte(CS.getStart()), 1410 diag::warn_printf_insufficient_data_args) 1411 << getSpecifierRange(startSpecifier, specifierLen); 1412 } 1413 1414 return false; 1415 } 1416 return true; 1417} 1418 1419//===--- CHECK: Printf format string checking ------------------------------===// 1420 1421namespace { 1422class CheckPrintfHandler : public CheckFormatHandler { 1423public: 1424 CheckPrintfHandler(Sema &s, const StringLiteral *fexpr, 1425 const Expr *origFormatExpr, unsigned firstDataArg, 1426 unsigned numDataArgs, bool isObjCLiteral, 1427 const char *beg, bool hasVAListArg, 1428 const CallExpr *theCall, unsigned formatIdx) 1429 : CheckFormatHandler(s, fexpr, origFormatExpr, firstDataArg, 1430 numDataArgs, isObjCLiteral, beg, hasVAListArg, 1431 theCall, formatIdx) {} 1432 1433 1434 bool HandleInvalidPrintfConversionSpecifier( 1435 const analyze_printf::PrintfSpecifier &FS, 1436 const char *startSpecifier, 1437 unsigned specifierLen); 1438 1439 bool HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier &FS, 1440 const char *startSpecifier, 1441 unsigned specifierLen); 1442 1443 bool HandleAmount(const analyze_format_string::OptionalAmount &Amt, unsigned k, 1444 const char *startSpecifier, unsigned specifierLen); 1445 void HandleInvalidAmount(const analyze_printf::PrintfSpecifier &FS, 1446 const analyze_printf::OptionalAmount &Amt, 1447 unsigned type, 1448 const char *startSpecifier, unsigned specifierLen); 1449 void HandleFlag(const analyze_printf::PrintfSpecifier &FS, 1450 const analyze_printf::OptionalFlag &flag, 1451 const char *startSpecifier, unsigned specifierLen); 1452 void HandleIgnoredFlag(const analyze_printf::PrintfSpecifier &FS, 1453 const analyze_printf::OptionalFlag &ignoredFlag, 1454 const analyze_printf::OptionalFlag &flag, 1455 const char *startSpecifier, unsigned specifierLen); 1456}; 1457} 1458 1459bool CheckPrintfHandler::HandleInvalidPrintfConversionSpecifier( 1460 const analyze_printf::PrintfSpecifier &FS, 1461 const char *startSpecifier, 1462 unsigned specifierLen) { 1463 const analyze_printf::PrintfConversionSpecifier &CS = 1464 FS.getConversionSpecifier(); 1465 1466 return HandleInvalidConversionSpecifier(FS.getArgIndex(), 1467 getLocationOfByte(CS.getStart()), 1468 startSpecifier, specifierLen, 1469 CS.getStart(), CS.getLength()); 1470} 1471 1472bool CheckPrintfHandler::HandleAmount( 1473 const analyze_format_string::OptionalAmount &Amt, 1474 unsigned k, const char *startSpecifier, 1475 unsigned specifierLen) { 1476 1477 if (Amt.hasDataArgument()) { 1478 if (!HasVAListArg) { 1479 unsigned argIndex = Amt.getArgIndex(); 1480 if (argIndex >= NumDataArgs) { 1481 S.Diag(getLocationOfByte(Amt.getStart()), 1482 diag::warn_printf_asterisk_missing_arg) 1483 << k << getSpecifierRange(startSpecifier, specifierLen); 1484 // Don't do any more checking. We will just emit 1485 // spurious errors. 1486 return false; 1487 } 1488 1489 // Type check the data argument. It should be an 'int'. 1490 // Although not in conformance with C99, we also allow the argument to be 1491 // an 'unsigned int' as that is a reasonably safe case. GCC also 1492 // doesn't emit a warning for that case. 1493 CoveredArgs.set(argIndex); 1494 const Expr *Arg = getDataArg(argIndex); 1495 QualType T = Arg->getType(); 1496 1497 const analyze_printf::ArgTypeResult &ATR = Amt.getArgType(S.Context); 1498 assert(ATR.isValid()); 1499 1500 if (!ATR.matchesType(S.Context, T)) { 1501 S.Diag(getLocationOfByte(Amt.getStart()), 1502 diag::warn_printf_asterisk_wrong_type) 1503 << k 1504 << ATR.getRepresentativeType(S.Context) << T 1505 << getSpecifierRange(startSpecifier, specifierLen) 1506 << Arg->getSourceRange(); 1507 // Don't do any more checking. We will just emit 1508 // spurious errors. 1509 return false; 1510 } 1511 } 1512 } 1513 return true; 1514} 1515 1516void CheckPrintfHandler::HandleInvalidAmount( 1517 const analyze_printf::PrintfSpecifier &FS, 1518 const analyze_printf::OptionalAmount &Amt, 1519 unsigned type, 1520 const char *startSpecifier, 1521 unsigned specifierLen) { 1522 const analyze_printf::PrintfConversionSpecifier &CS = 1523 FS.getConversionSpecifier(); 1524 switch (Amt.getHowSpecified()) { 1525 case analyze_printf::OptionalAmount::Constant: 1526 S.Diag(getLocationOfByte(Amt.getStart()), 1527 diag::warn_printf_nonsensical_optional_amount) 1528 << type 1529 << CS.toString() 1530 << getSpecifierRange(startSpecifier, specifierLen) 1531 << FixItHint::CreateRemoval(getSpecifierRange(Amt.getStart(), 1532 Amt.getConstantLength())); 1533 break; 1534 1535 default: 1536 S.Diag(getLocationOfByte(Amt.getStart()), 1537 diag::warn_printf_nonsensical_optional_amount) 1538 << type 1539 << CS.toString() 1540 << getSpecifierRange(startSpecifier, specifierLen); 1541 break; 1542 } 1543} 1544 1545void CheckPrintfHandler::HandleFlag(const analyze_printf::PrintfSpecifier &FS, 1546 const analyze_printf::OptionalFlag &flag, 1547 const char *startSpecifier, 1548 unsigned specifierLen) { 1549 // Warn about pointless flag with a fixit removal. 1550 const analyze_printf::PrintfConversionSpecifier &CS = 1551 FS.getConversionSpecifier(); 1552 S.Diag(getLocationOfByte(flag.getPosition()), 1553 diag::warn_printf_nonsensical_flag) 1554 << flag.toString() << CS.toString() 1555 << getSpecifierRange(startSpecifier, specifierLen) 1556 << FixItHint::CreateRemoval(getSpecifierRange(flag.getPosition(), 1)); 1557} 1558 1559void CheckPrintfHandler::HandleIgnoredFlag( 1560 const analyze_printf::PrintfSpecifier &FS, 1561 const analyze_printf::OptionalFlag &ignoredFlag, 1562 const analyze_printf::OptionalFlag &flag, 1563 const char *startSpecifier, 1564 unsigned specifierLen) { 1565 // Warn about ignored flag with a fixit removal. 1566 S.Diag(getLocationOfByte(ignoredFlag.getPosition()), 1567 diag::warn_printf_ignored_flag) 1568 << ignoredFlag.toString() << flag.toString() 1569 << getSpecifierRange(startSpecifier, specifierLen) 1570 << FixItHint::CreateRemoval(getSpecifierRange( 1571 ignoredFlag.getPosition(), 1)); 1572} 1573 1574bool 1575CheckPrintfHandler::HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier 1576 &FS, 1577 const char *startSpecifier, 1578 unsigned specifierLen) { 1579 1580 using namespace analyze_format_string; 1581 using namespace analyze_printf; 1582 const PrintfConversionSpecifier &CS = FS.getConversionSpecifier(); 1583 1584 if (FS.consumesDataArgument()) { 1585 if (atFirstArg) { 1586 atFirstArg = false; 1587 usesPositionalArgs = FS.usesPositionalArg(); 1588 } 1589 else if (usesPositionalArgs != FS.usesPositionalArg()) { 1590 // Cannot mix-and-match positional and non-positional arguments. 1591 S.Diag(getLocationOfByte(CS.getStart()), 1592 diag::warn_format_mix_positional_nonpositional_args) 1593 << getSpecifierRange(startSpecifier, specifierLen); 1594 return false; 1595 } 1596 } 1597 1598 // First check if the field width, precision, and conversion specifier 1599 // have matching data arguments. 1600 if (!HandleAmount(FS.getFieldWidth(), /* field width */ 0, 1601 startSpecifier, specifierLen)) { 1602 return false; 1603 } 1604 1605 if (!HandleAmount(FS.getPrecision(), /* precision */ 1, 1606 startSpecifier, specifierLen)) { 1607 return false; 1608 } 1609 1610 if (!CS.consumesDataArgument()) { 1611 // FIXME: Technically specifying a precision or field width here 1612 // makes no sense. Worth issuing a warning at some point. 1613 return true; 1614 } 1615 1616 // Consume the argument. 1617 unsigned argIndex = FS.getArgIndex(); 1618 if (argIndex < NumDataArgs) { 1619 // The check to see if the argIndex is valid will come later. 1620 // We set the bit here because we may exit early from this 1621 // function if we encounter some other error. 1622 CoveredArgs.set(argIndex); 1623 } 1624 1625 // Check for using an Objective-C specific conversion specifier 1626 // in a non-ObjC literal. 1627 if (!IsObjCLiteral && CS.isObjCArg()) { 1628 return HandleInvalidPrintfConversionSpecifier(FS, startSpecifier, 1629 specifierLen); 1630 } 1631 1632 // Check for invalid use of field width 1633 if (!FS.hasValidFieldWidth()) { 1634 HandleInvalidAmount(FS, FS.getFieldWidth(), /* field width */ 0, 1635 startSpecifier, specifierLen); 1636 } 1637 1638 // Check for invalid use of precision 1639 if (!FS.hasValidPrecision()) { 1640 HandleInvalidAmount(FS, FS.getPrecision(), /* precision */ 1, 1641 startSpecifier, specifierLen); 1642 } 1643 1644 // Check each flag does not conflict with any other component. 1645 if (!FS.hasValidThousandsGroupingPrefix()) 1646 HandleFlag(FS, FS.hasThousandsGrouping(), startSpecifier, specifierLen); 1647 if (!FS.hasValidLeadingZeros()) 1648 HandleFlag(FS, FS.hasLeadingZeros(), startSpecifier, specifierLen); 1649 if (!FS.hasValidPlusPrefix()) 1650 HandleFlag(FS, FS.hasPlusPrefix(), startSpecifier, specifierLen); 1651 if (!FS.hasValidSpacePrefix()) 1652 HandleFlag(FS, FS.hasSpacePrefix(), startSpecifier, specifierLen); 1653 if (!FS.hasValidAlternativeForm()) 1654 HandleFlag(FS, FS.hasAlternativeForm(), startSpecifier, specifierLen); 1655 if (!FS.hasValidLeftJustified()) 1656 HandleFlag(FS, FS.isLeftJustified(), startSpecifier, specifierLen); 1657 1658 // Check that flags are not ignored by another flag 1659 if (FS.hasSpacePrefix() && FS.hasPlusPrefix()) // ' ' ignored by '+' 1660 HandleIgnoredFlag(FS, FS.hasSpacePrefix(), FS.hasPlusPrefix(), 1661 startSpecifier, specifierLen); 1662 if (FS.hasLeadingZeros() && FS.isLeftJustified()) // '0' ignored by '-' 1663 HandleIgnoredFlag(FS, FS.hasLeadingZeros(), FS.isLeftJustified(), 1664 startSpecifier, specifierLen); 1665 1666 // Check the length modifier is valid with the given conversion specifier. 1667 const LengthModifier &LM = FS.getLengthModifier(); 1668 if (!FS.hasValidLengthModifier()) 1669 S.Diag(getLocationOfByte(LM.getStart()), 1670 diag::warn_format_nonsensical_length) 1671 << LM.toString() << CS.toString() 1672 << getSpecifierRange(startSpecifier, specifierLen) 1673 << FixItHint::CreateRemoval(getSpecifierRange(LM.getStart(), 1674 LM.getLength())); 1675 1676 // Are we using '%n'? 1677 if (CS.getKind() == ConversionSpecifier::nArg) { 1678 // Issue a warning about this being a possible security issue. 1679 S.Diag(getLocationOfByte(CS.getStart()), diag::warn_printf_write_back) 1680 << getSpecifierRange(startSpecifier, specifierLen); 1681 // Continue checking the other format specifiers. 1682 return true; 1683 } 1684 1685 // The remaining checks depend on the data arguments. 1686 if (HasVAListArg) 1687 return true; 1688 1689 if (!CheckNumArgs(FS, CS, startSpecifier, specifierLen, argIndex)) 1690 return false; 1691 1692 // Now type check the data expression that matches the 1693 // format specifier. 1694 const Expr *Ex = getDataArg(argIndex); 1695 const analyze_printf::ArgTypeResult &ATR = FS.getArgType(S.Context); 1696 if (ATR.isValid() && !ATR.matchesType(S.Context, Ex->getType())) { 1697 // Check if we didn't match because of an implicit cast from a 'char' 1698 // or 'short' to an 'int'. This is done because printf is a varargs 1699 // function. 1700 if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Ex)) 1701 if (ICE->getType() == S.Context.IntTy) { 1702 // All further checking is done on the subexpression. 1703 Ex = ICE->getSubExpr(); 1704 if (ATR.matchesType(S.Context, Ex->getType())) 1705 return true; 1706 } 1707 1708 // We may be able to offer a FixItHint if it is a supported type. 1709 PrintfSpecifier fixedFS = FS; 1710 bool success = fixedFS.fixType(Ex->getType()); 1711 1712 if (success) { 1713 // Get the fix string from the fixed format specifier 1714 llvm::SmallString<128> buf; 1715 llvm::raw_svector_ostream os(buf); 1716 fixedFS.toString(os); 1717 1718 // FIXME: getRepresentativeType() perhaps should return a string 1719 // instead of a QualType to better handle when the representative 1720 // type is 'wint_t' (which is defined in the system headers). 1721 S.Diag(getLocationOfByte(CS.getStart()), 1722 diag::warn_printf_conversion_argument_type_mismatch) 1723 << ATR.getRepresentativeType(S.Context) << Ex->getType() 1724 << getSpecifierRange(startSpecifier, specifierLen) 1725 << Ex->getSourceRange() 1726 << FixItHint::CreateReplacement( 1727 getSpecifierRange(startSpecifier, specifierLen), 1728 os.str()); 1729 } 1730 else { 1731 S.Diag(getLocationOfByte(CS.getStart()), 1732 diag::warn_printf_conversion_argument_type_mismatch) 1733 << ATR.getRepresentativeType(S.Context) << Ex->getType() 1734 << getSpecifierRange(startSpecifier, specifierLen) 1735 << Ex->getSourceRange(); 1736 } 1737 } 1738 1739 return true; 1740} 1741 1742//===--- CHECK: Scanf format string checking ------------------------------===// 1743 1744namespace { 1745class CheckScanfHandler : public CheckFormatHandler { 1746public: 1747 CheckScanfHandler(Sema &s, const StringLiteral *fexpr, 1748 const Expr *origFormatExpr, unsigned firstDataArg, 1749 unsigned numDataArgs, bool isObjCLiteral, 1750 const char *beg, bool hasVAListArg, 1751 const CallExpr *theCall, unsigned formatIdx) 1752 : CheckFormatHandler(s, fexpr, origFormatExpr, firstDataArg, 1753 numDataArgs, isObjCLiteral, beg, hasVAListArg, 1754 theCall, formatIdx) {} 1755 1756 bool HandleScanfSpecifier(const analyze_scanf::ScanfSpecifier &FS, 1757 const char *startSpecifier, 1758 unsigned specifierLen); 1759 1760 bool HandleInvalidScanfConversionSpecifier( 1761 const analyze_scanf::ScanfSpecifier &FS, 1762 const char *startSpecifier, 1763 unsigned specifierLen); 1764 1765 void HandleIncompleteScanList(const char *start, const char *end); 1766}; 1767} 1768 1769void CheckScanfHandler::HandleIncompleteScanList(const char *start, 1770 const char *end) { 1771 S.Diag(getLocationOfByte(end), diag::warn_scanf_scanlist_incomplete) 1772 << getSpecifierRange(start, end - start); 1773} 1774 1775bool CheckScanfHandler::HandleInvalidScanfConversionSpecifier( 1776 const analyze_scanf::ScanfSpecifier &FS, 1777 const char *startSpecifier, 1778 unsigned specifierLen) { 1779 1780 const analyze_scanf::ScanfConversionSpecifier &CS = 1781 FS.getConversionSpecifier(); 1782 1783 return HandleInvalidConversionSpecifier(FS.getArgIndex(), 1784 getLocationOfByte(CS.getStart()), 1785 startSpecifier, specifierLen, 1786 CS.getStart(), CS.getLength()); 1787} 1788 1789bool CheckScanfHandler::HandleScanfSpecifier( 1790 const analyze_scanf::ScanfSpecifier &FS, 1791 const char *startSpecifier, 1792 unsigned specifierLen) { 1793 1794 using namespace analyze_scanf; 1795 using namespace analyze_format_string; 1796 1797 const ScanfConversionSpecifier &CS = FS.getConversionSpecifier(); 1798 1799 // Handle case where '%' and '*' don't consume an argument. These shouldn't 1800 // be used to decide if we are using positional arguments consistently. 1801 if (FS.consumesDataArgument()) { 1802 if (atFirstArg) { 1803 atFirstArg = false; 1804 usesPositionalArgs = FS.usesPositionalArg(); 1805 } 1806 else if (usesPositionalArgs != FS.usesPositionalArg()) { 1807 // Cannot mix-and-match positional and non-positional arguments. 1808 S.Diag(getLocationOfByte(CS.getStart()), 1809 diag::warn_format_mix_positional_nonpositional_args) 1810 << getSpecifierRange(startSpecifier, specifierLen); 1811 return false; 1812 } 1813 } 1814 1815 // Check if the field with is non-zero. 1816 const OptionalAmount &Amt = FS.getFieldWidth(); 1817 if (Amt.getHowSpecified() == OptionalAmount::Constant) { 1818 if (Amt.getConstantAmount() == 0) { 1819 const CharSourceRange &R = getSpecifierRange(Amt.getStart(), 1820 Amt.getConstantLength()); 1821 S.Diag(getLocationOfByte(Amt.getStart()), 1822 diag::warn_scanf_nonzero_width) 1823 << R << FixItHint::CreateRemoval(R); 1824 } 1825 } 1826 1827 if (!FS.consumesDataArgument()) { 1828 // FIXME: Technically specifying a precision or field width here 1829 // makes no sense. Worth issuing a warning at some point. 1830 return true; 1831 } 1832 1833 // Consume the argument. 1834 unsigned argIndex = FS.getArgIndex(); 1835 if (argIndex < NumDataArgs) { 1836 // The check to see if the argIndex is valid will come later. 1837 // We set the bit here because we may exit early from this 1838 // function if we encounter some other error. 1839 CoveredArgs.set(argIndex); 1840 } 1841 1842 // Check the length modifier is valid with the given conversion specifier. 1843 const LengthModifier &LM = FS.getLengthModifier(); 1844 if (!FS.hasValidLengthModifier()) { 1845 S.Diag(getLocationOfByte(LM.getStart()), 1846 diag::warn_format_nonsensical_length) 1847 << LM.toString() << CS.toString() 1848 << getSpecifierRange(startSpecifier, specifierLen) 1849 << FixItHint::CreateRemoval(getSpecifierRange(LM.getStart(), 1850 LM.getLength())); 1851 } 1852 1853 // The remaining checks depend on the data arguments. 1854 if (HasVAListArg) 1855 return true; 1856 1857 if (!CheckNumArgs(FS, CS, startSpecifier, specifierLen, argIndex)) 1858 return false; 1859 1860 // FIXME: Check that the argument type matches the format specifier. 1861 1862 return true; 1863} 1864 1865void Sema::CheckFormatString(const StringLiteral *FExpr, 1866 const Expr *OrigFormatExpr, 1867 const CallExpr *TheCall, bool HasVAListArg, 1868 unsigned format_idx, unsigned firstDataArg, 1869 bool isPrintf) { 1870 1871 // CHECK: is the format string a wide literal? 1872 if (!FExpr->isAscii()) { 1873 Diag(FExpr->getLocStart(), 1874 diag::warn_format_string_is_wide_literal) 1875 << OrigFormatExpr->getSourceRange(); 1876 return; 1877 } 1878 1879 // Str - The format string. NOTE: this is NOT null-terminated! 1880 StringRef StrRef = FExpr->getString(); 1881 const char *Str = StrRef.data(); 1882 unsigned StrLen = StrRef.size(); 1883 1884 // CHECK: empty format string? 1885 if (StrLen == 0) { 1886 Diag(FExpr->getLocStart(), diag::warn_empty_format_string) 1887 << OrigFormatExpr->getSourceRange(); 1888 return; 1889 } 1890 1891 if (isPrintf) { 1892 CheckPrintfHandler H(*this, FExpr, OrigFormatExpr, firstDataArg, 1893 TheCall->getNumArgs() - firstDataArg, 1894 isa<ObjCStringLiteral>(OrigFormatExpr), Str, 1895 HasVAListArg, TheCall, format_idx); 1896 1897 if (!analyze_format_string::ParsePrintfString(H, Str, Str + StrLen)) 1898 H.DoneProcessing(); 1899 } 1900 else { 1901 CheckScanfHandler H(*this, FExpr, OrigFormatExpr, firstDataArg, 1902 TheCall->getNumArgs() - firstDataArg, 1903 isa<ObjCStringLiteral>(OrigFormatExpr), Str, 1904 HasVAListArg, TheCall, format_idx); 1905 1906 if (!analyze_format_string::ParseScanfString(H, Str, Str + StrLen)) 1907 H.DoneProcessing(); 1908 } 1909} 1910 1911//===--- CHECK: Standard memory functions ---------------------------------===// 1912 1913/// \brief Determine whether the given type is a dynamic class type (e.g., 1914/// whether it has a vtable). 1915static bool isDynamicClassType(QualType T) { 1916 if (CXXRecordDecl *Record = T->getAsCXXRecordDecl()) 1917 if (CXXRecordDecl *Definition = Record->getDefinition()) 1918 if (Definition->isDynamicClass()) 1919 return true; 1920 1921 return false; 1922} 1923 1924/// \brief If E is a sizeof expression, returns its argument expression, 1925/// otherwise returns NULL. 1926static const Expr *getSizeOfExprArg(const Expr* E) { 1927 if (const UnaryExprOrTypeTraitExpr *SizeOf = 1928 dyn_cast<UnaryExprOrTypeTraitExpr>(E)) 1929 if (SizeOf->getKind() == clang::UETT_SizeOf && !SizeOf->isArgumentType()) 1930 return SizeOf->getArgumentExpr()->IgnoreParenImpCasts(); 1931 1932 return 0; 1933} 1934 1935/// \brief If E is a sizeof expression, returns its argument type. 1936static QualType getSizeOfArgType(const Expr* E) { 1937 if (const UnaryExprOrTypeTraitExpr *SizeOf = 1938 dyn_cast<UnaryExprOrTypeTraitExpr>(E)) 1939 if (SizeOf->getKind() == clang::UETT_SizeOf) 1940 return SizeOf->getTypeOfArgument(); 1941 1942 return QualType(); 1943} 1944 1945/// \brief Check for dangerous or invalid arguments to memset(). 1946/// 1947/// This issues warnings on known problematic, dangerous or unspecified 1948/// arguments to the standard 'memset', 'memcpy', 'memmove', and 'memcmp' 1949/// function calls. 1950/// 1951/// \param Call The call expression to diagnose. 1952void Sema::CheckMemaccessArguments(const CallExpr *Call, 1953 CheckedMemoryFunction CMF, 1954 IdentifierInfo *FnName) { 1955 // It is possible to have a non-standard definition of memset. Validate 1956 // we have enough arguments, and if not, abort further checking. 1957 if (Call->getNumArgs() < 3) 1958 return; 1959 1960 unsigned LastArg = (CMF == CMF_Memset? 1 : 2); 1961 const Expr *LenExpr = Call->getArg(2)->IgnoreParenImpCasts(); 1962 1963 // We have special checking when the length is a sizeof expression. 1964 QualType SizeOfArgTy = getSizeOfArgType(LenExpr); 1965 const Expr *SizeOfArg = getSizeOfExprArg(LenExpr); 1966 llvm::FoldingSetNodeID SizeOfArgID; 1967 1968 for (unsigned ArgIdx = 0; ArgIdx != LastArg; ++ArgIdx) { 1969 const Expr *Dest = Call->getArg(ArgIdx)->IgnoreParenImpCasts(); 1970 SourceRange ArgRange = Call->getArg(ArgIdx)->getSourceRange(); 1971 1972 QualType DestTy = Dest->getType(); 1973 if (const PointerType *DestPtrTy = DestTy->getAs<PointerType>()) { 1974 QualType PointeeTy = DestPtrTy->getPointeeType(); 1975 1976 // Never warn about void type pointers. This can be used to suppress 1977 // false positives. 1978 if (PointeeTy->isVoidType()) 1979 continue; 1980 1981 // Catch "memset(p, 0, sizeof(p))" -- needs to be sizeof(*p). Do this by 1982 // actually comparing the expressions for equality. Because computing the 1983 // expression IDs can be expensive, we only do this if the diagnostic is 1984 // enabled. 1985 if (SizeOfArg && 1986 Diags.getDiagnosticLevel(diag::warn_sizeof_pointer_expr_memaccess, 1987 SizeOfArg->getExprLoc())) { 1988 // We only compute IDs for expressions if the warning is enabled, and 1989 // cache the sizeof arg's ID. 1990 if (SizeOfArgID == llvm::FoldingSetNodeID()) 1991 SizeOfArg->Profile(SizeOfArgID, Context, true); 1992 llvm::FoldingSetNodeID DestID; 1993 Dest->Profile(DestID, Context, true); 1994 if (DestID == SizeOfArgID) { 1995 unsigned ActionIdx = 0; // Default is to suggest dereferencing. 1996 if (const UnaryOperator *UnaryOp = dyn_cast<UnaryOperator>(Dest)) 1997 if (UnaryOp->getOpcode() == UO_AddrOf) 1998 ActionIdx = 1; // If its an address-of operator, just remove it. 1999 if (Context.getTypeSize(PointeeTy) == Context.getCharWidth()) 2000 ActionIdx = 2; // If the pointee's size is sizeof(char), 2001 // suggest an explicit length. 2002 DiagRuntimeBehavior(SizeOfArg->getExprLoc(), Dest, 2003 PDiag(diag::warn_sizeof_pointer_expr_memaccess) 2004 << FnName << ArgIdx << ActionIdx 2005 << Dest->getSourceRange() 2006 << SizeOfArg->getSourceRange()); 2007 break; 2008 } 2009 } 2010 2011 // Also check for cases where the sizeof argument is the exact same 2012 // type as the memory argument, and where it points to a user-defined 2013 // record type. 2014 if (SizeOfArgTy != QualType()) { 2015 if (PointeeTy->isRecordType() && 2016 Context.typesAreCompatible(SizeOfArgTy, DestTy)) { 2017 DiagRuntimeBehavior(LenExpr->getExprLoc(), Dest, 2018 PDiag(diag::warn_sizeof_pointer_type_memaccess) 2019 << FnName << SizeOfArgTy << ArgIdx 2020 << PointeeTy << Dest->getSourceRange() 2021 << LenExpr->getSourceRange()); 2022 break; 2023 } 2024 } 2025 2026 // Always complain about dynamic classes. 2027 if (isDynamicClassType(PointeeTy)) 2028 DiagRuntimeBehavior( 2029 Dest->getExprLoc(), Dest, 2030 PDiag(diag::warn_dyn_class_memaccess) 2031 << (CMF == CMF_Memcmp ? ArgIdx + 2 : ArgIdx) << FnName << PointeeTy 2032 // "overwritten" if we're warning about the destination for any call 2033 // but memcmp; otherwise a verb appropriate to the call. 2034 << (ArgIdx == 0 && CMF != CMF_Memcmp ? 0 : (unsigned)CMF) 2035 << Call->getCallee()->getSourceRange()); 2036 else if (PointeeTy.hasNonTrivialObjCLifetime() && CMF != CMF_Memset) 2037 DiagRuntimeBehavior( 2038 Dest->getExprLoc(), Dest, 2039 PDiag(diag::warn_arc_object_memaccess) 2040 << ArgIdx << FnName << PointeeTy 2041 << Call->getCallee()->getSourceRange()); 2042 else 2043 continue; 2044 2045 DiagRuntimeBehavior( 2046 Dest->getExprLoc(), Dest, 2047 PDiag(diag::note_bad_memaccess_silence) 2048 << FixItHint::CreateInsertion(ArgRange.getBegin(), "(void*)")); 2049 break; 2050 } 2051 } 2052} 2053 2054// A little helper routine: ignore addition and subtraction of integer literals. 2055// This intentionally does not ignore all integer constant expressions because 2056// we don't want to remove sizeof(). 2057static const Expr *ignoreLiteralAdditions(const Expr *Ex, ASTContext &Ctx) { 2058 Ex = Ex->IgnoreParenCasts(); 2059 2060 for (;;) { 2061 const BinaryOperator * BO = dyn_cast<BinaryOperator>(Ex); 2062 if (!BO || !BO->isAdditiveOp()) 2063 break; 2064 2065 const Expr *RHS = BO->getRHS()->IgnoreParenCasts(); 2066 const Expr *LHS = BO->getLHS()->IgnoreParenCasts(); 2067 2068 if (isa<IntegerLiteral>(RHS)) 2069 Ex = LHS; 2070 else if (isa<IntegerLiteral>(LHS)) 2071 Ex = RHS; 2072 else 2073 break; 2074 } 2075 2076 return Ex; 2077} 2078 2079// Warn if the user has made the 'size' argument to strlcpy or strlcat 2080// be the size of the source, instead of the destination. 2081void Sema::CheckStrlcpycatArguments(const CallExpr *Call, 2082 IdentifierInfo *FnName) { 2083 2084 // Don't crash if the user has the wrong number of arguments 2085 if (Call->getNumArgs() != 3) 2086 return; 2087 2088 const Expr *SrcArg = ignoreLiteralAdditions(Call->getArg(1), Context); 2089 const Expr *SizeArg = ignoreLiteralAdditions(Call->getArg(2), Context); 2090 const Expr *CompareWithSrc = NULL; 2091 2092 // Look for 'strlcpy(dst, x, sizeof(x))' 2093 if (const Expr *Ex = getSizeOfExprArg(SizeArg)) 2094 CompareWithSrc = Ex; 2095 else { 2096 // Look for 'strlcpy(dst, x, strlen(x))' 2097 if (const CallExpr *SizeCall = dyn_cast<CallExpr>(SizeArg)) { 2098 if (SizeCall->isBuiltinCall(Context) == Builtin::BIstrlen 2099 && SizeCall->getNumArgs() == 1) 2100 CompareWithSrc = ignoreLiteralAdditions(SizeCall->getArg(0), Context); 2101 } 2102 } 2103 2104 if (!CompareWithSrc) 2105 return; 2106 2107 // Determine if the argument to sizeof/strlen is equal to the source 2108 // argument. In principle there's all kinds of things you could do 2109 // here, for instance creating an == expression and evaluating it with 2110 // EvaluateAsBooleanCondition, but this uses a more direct technique: 2111 const DeclRefExpr *SrcArgDRE = dyn_cast<DeclRefExpr>(SrcArg); 2112 if (!SrcArgDRE) 2113 return; 2114 2115 const DeclRefExpr *CompareWithSrcDRE = dyn_cast<DeclRefExpr>(CompareWithSrc); 2116 if (!CompareWithSrcDRE || 2117 SrcArgDRE->getDecl() != CompareWithSrcDRE->getDecl()) 2118 return; 2119 2120 const Expr *OriginalSizeArg = Call->getArg(2); 2121 Diag(CompareWithSrcDRE->getLocStart(), diag::warn_strlcpycat_wrong_size) 2122 << OriginalSizeArg->getSourceRange() << FnName; 2123 2124 // Output a FIXIT hint if the destination is an array (rather than a 2125 // pointer to an array). This could be enhanced to handle some 2126 // pointers if we know the actual size, like if DstArg is 'array+2' 2127 // we could say 'sizeof(array)-2'. 2128 const Expr *DstArg = Call->getArg(0)->IgnoreParenImpCasts(); 2129 QualType DstArgTy = DstArg->getType(); 2130 2131 // Only handle constant-sized or VLAs, but not flexible members. 2132 if (const ConstantArrayType *CAT = Context.getAsConstantArrayType(DstArgTy)) { 2133 // Only issue the FIXIT for arrays of size > 1. 2134 if (CAT->getSize().getSExtValue() <= 1) 2135 return; 2136 } else if (!DstArgTy->isVariableArrayType()) { 2137 return; 2138 } 2139 2140 llvm::SmallString<128> sizeString; 2141 llvm::raw_svector_ostream OS(sizeString); 2142 OS << "sizeof("; 2143 DstArg->printPretty(OS, Context, 0, Context.PrintingPolicy); 2144 OS << ")"; 2145 2146 Diag(OriginalSizeArg->getLocStart(), diag::note_strlcpycat_wrong_size) 2147 << FixItHint::CreateReplacement(OriginalSizeArg->getSourceRange(), 2148 OS.str()); 2149} 2150 2151//===--- CHECK: Return Address of Stack Variable --------------------------===// 2152 2153static Expr *EvalVal(Expr *E, SmallVectorImpl<DeclRefExpr *> &refVars); 2154static Expr *EvalAddr(Expr* E, SmallVectorImpl<DeclRefExpr *> &refVars); 2155 2156/// CheckReturnStackAddr - Check if a return statement returns the address 2157/// of a stack variable. 2158void 2159Sema::CheckReturnStackAddr(Expr *RetValExp, QualType lhsType, 2160 SourceLocation ReturnLoc) { 2161 2162 Expr *stackE = 0; 2163 SmallVector<DeclRefExpr *, 8> refVars; 2164 2165 // Perform checking for returned stack addresses, local blocks, 2166 // label addresses or references to temporaries. 2167 if (lhsType->isPointerType() || 2168 (!getLangOptions().ObjCAutoRefCount && lhsType->isBlockPointerType())) { 2169 stackE = EvalAddr(RetValExp, refVars); 2170 } else if (lhsType->isReferenceType()) { 2171 stackE = EvalVal(RetValExp, refVars); 2172 } 2173 2174 if (stackE == 0) 2175 return; // Nothing suspicious was found. 2176 2177 SourceLocation diagLoc; 2178 SourceRange diagRange; 2179 if (refVars.empty()) { 2180 diagLoc = stackE->getLocStart(); 2181 diagRange = stackE->getSourceRange(); 2182 } else { 2183 // We followed through a reference variable. 'stackE' contains the 2184 // problematic expression but we will warn at the return statement pointing 2185 // at the reference variable. We will later display the "trail" of 2186 // reference variables using notes. 2187 diagLoc = refVars[0]->getLocStart(); 2188 diagRange = refVars[0]->getSourceRange(); 2189 } 2190 2191 if (DeclRefExpr *DR = dyn_cast<DeclRefExpr>(stackE)) { //address of local var. 2192 Diag(diagLoc, lhsType->isReferenceType() ? diag::warn_ret_stack_ref 2193 : diag::warn_ret_stack_addr) 2194 << DR->getDecl()->getDeclName() << diagRange; 2195 } else if (isa<BlockExpr>(stackE)) { // local block. 2196 Diag(diagLoc, diag::err_ret_local_block) << diagRange; 2197 } else if (isa<AddrLabelExpr>(stackE)) { // address of label. 2198 Diag(diagLoc, diag::warn_ret_addr_label) << diagRange; 2199 } else { // local temporary. 2200 Diag(diagLoc, lhsType->isReferenceType() ? diag::warn_ret_local_temp_ref 2201 : diag::warn_ret_local_temp_addr) 2202 << diagRange; 2203 } 2204 2205 // Display the "trail" of reference variables that we followed until we 2206 // found the problematic expression using notes. 2207 for (unsigned i = 0, e = refVars.size(); i != e; ++i) { 2208 VarDecl *VD = cast<VarDecl>(refVars[i]->getDecl()); 2209 // If this var binds to another reference var, show the range of the next 2210 // var, otherwise the var binds to the problematic expression, in which case 2211 // show the range of the expression. 2212 SourceRange range = (i < e-1) ? refVars[i+1]->getSourceRange() 2213 : stackE->getSourceRange(); 2214 Diag(VD->getLocation(), diag::note_ref_var_local_bind) 2215 << VD->getDeclName() << range; 2216 } 2217} 2218 2219/// EvalAddr - EvalAddr and EvalVal are mutually recursive functions that 2220/// check if the expression in a return statement evaluates to an address 2221/// to a location on the stack, a local block, an address of a label, or a 2222/// reference to local temporary. The recursion is used to traverse the 2223/// AST of the return expression, with recursion backtracking when we 2224/// encounter a subexpression that (1) clearly does not lead to one of the 2225/// above problematic expressions (2) is something we cannot determine leads to 2226/// a problematic expression based on such local checking. 2227/// 2228/// Both EvalAddr and EvalVal follow through reference variables to evaluate 2229/// the expression that they point to. Such variables are added to the 2230/// 'refVars' vector so that we know what the reference variable "trail" was. 2231/// 2232/// EvalAddr processes expressions that are pointers that are used as 2233/// references (and not L-values). EvalVal handles all other values. 2234/// At the base case of the recursion is a check for the above problematic 2235/// expressions. 2236/// 2237/// This implementation handles: 2238/// 2239/// * pointer-to-pointer casts 2240/// * implicit conversions from array references to pointers 2241/// * taking the address of fields 2242/// * arbitrary interplay between "&" and "*" operators 2243/// * pointer arithmetic from an address of a stack variable 2244/// * taking the address of an array element where the array is on the stack 2245static Expr *EvalAddr(Expr *E, SmallVectorImpl<DeclRefExpr *> &refVars) { 2246 if (E->isTypeDependent()) 2247 return NULL; 2248 2249 // We should only be called for evaluating pointer expressions. 2250 assert((E->getType()->isAnyPointerType() || 2251 E->getType()->isBlockPointerType() || 2252 E->getType()->isObjCQualifiedIdType()) && 2253 "EvalAddr only works on pointers"); 2254 2255 E = E->IgnoreParens(); 2256 2257 // Our "symbolic interpreter" is just a dispatch off the currently 2258 // viewed AST node. We then recursively traverse the AST by calling 2259 // EvalAddr and EvalVal appropriately. 2260 switch (E->getStmtClass()) { 2261 case Stmt::DeclRefExprClass: { 2262 DeclRefExpr *DR = cast<DeclRefExpr>(E); 2263 2264 if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl())) 2265 // If this is a reference variable, follow through to the expression that 2266 // it points to. 2267 if (V->hasLocalStorage() && 2268 V->getType()->isReferenceType() && V->hasInit()) { 2269 // Add the reference variable to the "trail". 2270 refVars.push_back(DR); 2271 return EvalAddr(V->getInit(), refVars); 2272 } 2273 2274 return NULL; 2275 } 2276 2277 case Stmt::UnaryOperatorClass: { 2278 // The only unary operator that make sense to handle here 2279 // is AddrOf. All others don't make sense as pointers. 2280 UnaryOperator *U = cast<UnaryOperator>(E); 2281 2282 if (U->getOpcode() == UO_AddrOf) 2283 return EvalVal(U->getSubExpr(), refVars); 2284 else 2285 return NULL; 2286 } 2287 2288 case Stmt::BinaryOperatorClass: { 2289 // Handle pointer arithmetic. All other binary operators are not valid 2290 // in this context. 2291 BinaryOperator *B = cast<BinaryOperator>(E); 2292 BinaryOperatorKind op = B->getOpcode(); 2293 2294 if (op != BO_Add && op != BO_Sub) 2295 return NULL; 2296 2297 Expr *Base = B->getLHS(); 2298 2299 // Determine which argument is the real pointer base. It could be 2300 // the RHS argument instead of the LHS. 2301 if (!Base->getType()->isPointerType()) Base = B->getRHS(); 2302 2303 assert (Base->getType()->isPointerType()); 2304 return EvalAddr(Base, refVars); 2305 } 2306 2307 // For conditional operators we need to see if either the LHS or RHS are 2308 // valid DeclRefExpr*s. If one of them is valid, we return it. 2309 case Stmt::ConditionalOperatorClass: { 2310 ConditionalOperator *C = cast<ConditionalOperator>(E); 2311 2312 // Handle the GNU extension for missing LHS. 2313 if (Expr *lhsExpr = C->getLHS()) { 2314 // In C++, we can have a throw-expression, which has 'void' type. 2315 if (!lhsExpr->getType()->isVoidType()) 2316 if (Expr* LHS = EvalAddr(lhsExpr, refVars)) 2317 return LHS; 2318 } 2319 2320 // In C++, we can have a throw-expression, which has 'void' type. 2321 if (C->getRHS()->getType()->isVoidType()) 2322 return NULL; 2323 2324 return EvalAddr(C->getRHS(), refVars); 2325 } 2326 2327 case Stmt::BlockExprClass: 2328 if (cast<BlockExpr>(E)->getBlockDecl()->hasCaptures()) 2329 return E; // local block. 2330 return NULL; 2331 2332 case Stmt::AddrLabelExprClass: 2333 return E; // address of label. 2334 2335 // For casts, we need to handle conversions from arrays to 2336 // pointer values, and pointer-to-pointer conversions. 2337 case Stmt::ImplicitCastExprClass: 2338 case Stmt::CStyleCastExprClass: 2339 case Stmt::CXXFunctionalCastExprClass: 2340 case Stmt::ObjCBridgedCastExprClass: { 2341 Expr* SubExpr = cast<CastExpr>(E)->getSubExpr(); 2342 QualType T = SubExpr->getType(); 2343 2344 if (SubExpr->getType()->isPointerType() || 2345 SubExpr->getType()->isBlockPointerType() || 2346 SubExpr->getType()->isObjCQualifiedIdType()) 2347 return EvalAddr(SubExpr, refVars); 2348 else if (T->isArrayType()) 2349 return EvalVal(SubExpr, refVars); 2350 else 2351 return 0; 2352 } 2353 2354 // C++ casts. For dynamic casts, static casts, and const casts, we 2355 // are always converting from a pointer-to-pointer, so we just blow 2356 // through the cast. In the case the dynamic cast doesn't fail (and 2357 // return NULL), we take the conservative route and report cases 2358 // where we return the address of a stack variable. For Reinterpre 2359 // FIXME: The comment about is wrong; we're not always converting 2360 // from pointer to pointer. I'm guessing that this code should also 2361 // handle references to objects. 2362 case Stmt::CXXStaticCastExprClass: 2363 case Stmt::CXXDynamicCastExprClass: 2364 case Stmt::CXXConstCastExprClass: 2365 case Stmt::CXXReinterpretCastExprClass: { 2366 Expr *S = cast<CXXNamedCastExpr>(E)->getSubExpr(); 2367 if (S->getType()->isPointerType() || S->getType()->isBlockPointerType()) 2368 return EvalAddr(S, refVars); 2369 else 2370 return NULL; 2371 } 2372 2373 case Stmt::MaterializeTemporaryExprClass: 2374 if (Expr *Result = EvalAddr( 2375 cast<MaterializeTemporaryExpr>(E)->GetTemporaryExpr(), 2376 refVars)) 2377 return Result; 2378 2379 return E; 2380 2381 // Everything else: we simply don't reason about them. 2382 default: 2383 return NULL; 2384 } 2385} 2386 2387 2388/// EvalVal - This function is complements EvalAddr in the mutual recursion. 2389/// See the comments for EvalAddr for more details. 2390static Expr *EvalVal(Expr *E, SmallVectorImpl<DeclRefExpr *> &refVars) { 2391do { 2392 // We should only be called for evaluating non-pointer expressions, or 2393 // expressions with a pointer type that are not used as references but instead 2394 // are l-values (e.g., DeclRefExpr with a pointer type). 2395 2396 // Our "symbolic interpreter" is just a dispatch off the currently 2397 // viewed AST node. We then recursively traverse the AST by calling 2398 // EvalAddr and EvalVal appropriately. 2399 2400 E = E->IgnoreParens(); 2401 switch (E->getStmtClass()) { 2402 case Stmt::ImplicitCastExprClass: { 2403 ImplicitCastExpr *IE = cast<ImplicitCastExpr>(E); 2404 if (IE->getValueKind() == VK_LValue) { 2405 E = IE->getSubExpr(); 2406 continue; 2407 } 2408 return NULL; 2409 } 2410 2411 case Stmt::DeclRefExprClass: { 2412 // When we hit a DeclRefExpr we are looking at code that refers to a 2413 // variable's name. If it's not a reference variable we check if it has 2414 // local storage within the function, and if so, return the expression. 2415 DeclRefExpr *DR = cast<DeclRefExpr>(E); 2416 2417 if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl())) 2418 if (V->hasLocalStorage()) { 2419 if (!V->getType()->isReferenceType()) 2420 return DR; 2421 2422 // Reference variable, follow through to the expression that 2423 // it points to. 2424 if (V->hasInit()) { 2425 // Add the reference variable to the "trail". 2426 refVars.push_back(DR); 2427 return EvalVal(V->getInit(), refVars); 2428 } 2429 } 2430 2431 return NULL; 2432 } 2433 2434 case Stmt::UnaryOperatorClass: { 2435 // The only unary operator that make sense to handle here 2436 // is Deref. All others don't resolve to a "name." This includes 2437 // handling all sorts of rvalues passed to a unary operator. 2438 UnaryOperator *U = cast<UnaryOperator>(E); 2439 2440 if (U->getOpcode() == UO_Deref) 2441 return EvalAddr(U->getSubExpr(), refVars); 2442 2443 return NULL; 2444 } 2445 2446 case Stmt::ArraySubscriptExprClass: { 2447 // Array subscripts are potential references to data on the stack. We 2448 // retrieve the DeclRefExpr* for the array variable if it indeed 2449 // has local storage. 2450 return EvalAddr(cast<ArraySubscriptExpr>(E)->getBase(), refVars); 2451 } 2452 2453 case Stmt::ConditionalOperatorClass: { 2454 // For conditional operators we need to see if either the LHS or RHS are 2455 // non-NULL Expr's. If one is non-NULL, we return it. 2456 ConditionalOperator *C = cast<ConditionalOperator>(E); 2457 2458 // Handle the GNU extension for missing LHS. 2459 if (Expr *lhsExpr = C->getLHS()) 2460 if (Expr *LHS = EvalVal(lhsExpr, refVars)) 2461 return LHS; 2462 2463 return EvalVal(C->getRHS(), refVars); 2464 } 2465 2466 // Accesses to members are potential references to data on the stack. 2467 case Stmt::MemberExprClass: { 2468 MemberExpr *M = cast<MemberExpr>(E); 2469 2470 // Check for indirect access. We only want direct field accesses. 2471 if (M->isArrow()) 2472 return NULL; 2473 2474 // Check whether the member type is itself a reference, in which case 2475 // we're not going to refer to the member, but to what the member refers to. 2476 if (M->getMemberDecl()->getType()->isReferenceType()) 2477 return NULL; 2478 2479 return EvalVal(M->getBase(), refVars); 2480 } 2481 2482 case Stmt::MaterializeTemporaryExprClass: 2483 if (Expr *Result = EvalVal( 2484 cast<MaterializeTemporaryExpr>(E)->GetTemporaryExpr(), 2485 refVars)) 2486 return Result; 2487 2488 return E; 2489 2490 default: 2491 // Check that we don't return or take the address of a reference to a 2492 // temporary. This is only useful in C++. 2493 if (!E->isTypeDependent() && E->isRValue()) 2494 return E; 2495 2496 // Everything else: we simply don't reason about them. 2497 return NULL; 2498 } 2499} while (true); 2500} 2501 2502//===--- CHECK: Floating-Point comparisons (-Wfloat-equal) ---------------===// 2503 2504/// Check for comparisons of floating point operands using != and ==. 2505/// Issue a warning if these are no self-comparisons, as they are not likely 2506/// to do what the programmer intended. 2507void Sema::CheckFloatComparison(SourceLocation loc, Expr* lex, Expr *rex) { 2508 bool EmitWarning = true; 2509 2510 Expr* LeftExprSansParen = lex->IgnoreParenImpCasts(); 2511 Expr* RightExprSansParen = rex->IgnoreParenImpCasts(); 2512 2513 // Special case: check for x == x (which is OK). 2514 // Do not emit warnings for such cases. 2515 if (DeclRefExpr* DRL = dyn_cast<DeclRefExpr>(LeftExprSansParen)) 2516 if (DeclRefExpr* DRR = dyn_cast<DeclRefExpr>(RightExprSansParen)) 2517 if (DRL->getDecl() == DRR->getDecl()) 2518 EmitWarning = false; 2519 2520 2521 // Special case: check for comparisons against literals that can be exactly 2522 // represented by APFloat. In such cases, do not emit a warning. This 2523 // is a heuristic: often comparison against such literals are used to 2524 // detect if a value in a variable has not changed. This clearly can 2525 // lead to false negatives. 2526 if (EmitWarning) { 2527 if (FloatingLiteral* FLL = dyn_cast<FloatingLiteral>(LeftExprSansParen)) { 2528 if (FLL->isExact()) 2529 EmitWarning = false; 2530 } else 2531 if (FloatingLiteral* FLR = dyn_cast<FloatingLiteral>(RightExprSansParen)){ 2532 if (FLR->isExact()) 2533 EmitWarning = false; 2534 } 2535 } 2536 2537 // Check for comparisons with builtin types. 2538 if (EmitWarning) 2539 if (CallExpr* CL = dyn_cast<CallExpr>(LeftExprSansParen)) 2540 if (CL->isBuiltinCall(Context)) 2541 EmitWarning = false; 2542 2543 if (EmitWarning) 2544 if (CallExpr* CR = dyn_cast<CallExpr>(RightExprSansParen)) 2545 if (CR->isBuiltinCall(Context)) 2546 EmitWarning = false; 2547 2548 // Emit the diagnostic. 2549 if (EmitWarning) 2550 Diag(loc, diag::warn_floatingpoint_eq) 2551 << lex->getSourceRange() << rex->getSourceRange(); 2552} 2553 2554//===--- CHECK: Integer mixed-sign comparisons (-Wsign-compare) --------===// 2555//===--- CHECK: Lossy implicit conversions (-Wconversion) --------------===// 2556 2557namespace { 2558 2559/// Structure recording the 'active' range of an integer-valued 2560/// expression. 2561struct IntRange { 2562 /// The number of bits active in the int. 2563 unsigned Width; 2564 2565 /// True if the int is known not to have negative values. 2566 bool NonNegative; 2567 2568 IntRange(unsigned Width, bool NonNegative) 2569 : Width(Width), NonNegative(NonNegative) 2570 {} 2571 2572 /// Returns the range of the bool type. 2573 static IntRange forBoolType() { 2574 return IntRange(1, true); 2575 } 2576 2577 /// Returns the range of an opaque value of the given integral type. 2578 static IntRange forValueOfType(ASTContext &C, QualType T) { 2579 return forValueOfCanonicalType(C, 2580 T->getCanonicalTypeInternal().getTypePtr()); 2581 } 2582 2583 /// Returns the range of an opaque value of a canonical integral type. 2584 static IntRange forValueOfCanonicalType(ASTContext &C, const Type *T) { 2585 assert(T->isCanonicalUnqualified()); 2586 2587 if (const VectorType *VT = dyn_cast<VectorType>(T)) 2588 T = VT->getElementType().getTypePtr(); 2589 if (const ComplexType *CT = dyn_cast<ComplexType>(T)) 2590 T = CT->getElementType().getTypePtr(); 2591 2592 // For enum types, use the known bit width of the enumerators. 2593 if (const EnumType *ET = dyn_cast<EnumType>(T)) { 2594 EnumDecl *Enum = ET->getDecl(); 2595 if (!Enum->isDefinition()) 2596 return IntRange(C.getIntWidth(QualType(T, 0)), false); 2597 2598 unsigned NumPositive = Enum->getNumPositiveBits(); 2599 unsigned NumNegative = Enum->getNumNegativeBits(); 2600 2601 return IntRange(std::max(NumPositive, NumNegative), NumNegative == 0); 2602 } 2603 2604 const BuiltinType *BT = cast<BuiltinType>(T); 2605 assert(BT->isInteger()); 2606 2607 return IntRange(C.getIntWidth(QualType(T, 0)), BT->isUnsignedInteger()); 2608 } 2609 2610 /// Returns the "target" range of a canonical integral type, i.e. 2611 /// the range of values expressible in the type. 2612 /// 2613 /// This matches forValueOfCanonicalType except that enums have the 2614 /// full range of their type, not the range of their enumerators. 2615 static IntRange forTargetOfCanonicalType(ASTContext &C, const Type *T) { 2616 assert(T->isCanonicalUnqualified()); 2617 2618 if (const VectorType *VT = dyn_cast<VectorType>(T)) 2619 T = VT->getElementType().getTypePtr(); 2620 if (const ComplexType *CT = dyn_cast<ComplexType>(T)) 2621 T = CT->getElementType().getTypePtr(); 2622 if (const EnumType *ET = dyn_cast<EnumType>(T)) 2623 T = C.getCanonicalType(ET->getDecl()->getIntegerType()).getTypePtr(); 2624 2625 const BuiltinType *BT = cast<BuiltinType>(T); 2626 assert(BT->isInteger()); 2627 2628 return IntRange(C.getIntWidth(QualType(T, 0)), BT->isUnsignedInteger()); 2629 } 2630 2631 /// Returns the supremum of two ranges: i.e. their conservative merge. 2632 static IntRange join(IntRange L, IntRange R) { 2633 return IntRange(std::max(L.Width, R.Width), 2634 L.NonNegative && R.NonNegative); 2635 } 2636 2637 /// Returns the infinum of two ranges: i.e. their aggressive merge. 2638 static IntRange meet(IntRange L, IntRange R) { 2639 return IntRange(std::min(L.Width, R.Width), 2640 L.NonNegative || R.NonNegative); 2641 } 2642}; 2643 2644IntRange GetValueRange(ASTContext &C, llvm::APSInt &value, unsigned MaxWidth) { 2645 if (value.isSigned() && value.isNegative()) 2646 return IntRange(value.getMinSignedBits(), false); 2647 2648 if (value.getBitWidth() > MaxWidth) 2649 value = value.trunc(MaxWidth); 2650 2651 // isNonNegative() just checks the sign bit without considering 2652 // signedness. 2653 return IntRange(value.getActiveBits(), true); 2654} 2655 2656IntRange GetValueRange(ASTContext &C, APValue &result, QualType Ty, 2657 unsigned MaxWidth) { 2658 if (result.isInt()) 2659 return GetValueRange(C, result.getInt(), MaxWidth); 2660 2661 if (result.isVector()) { 2662 IntRange R = GetValueRange(C, result.getVectorElt(0), Ty, MaxWidth); 2663 for (unsigned i = 1, e = result.getVectorLength(); i != e; ++i) { 2664 IntRange El = GetValueRange(C, result.getVectorElt(i), Ty, MaxWidth); 2665 R = IntRange::join(R, El); 2666 } 2667 return R; 2668 } 2669 2670 if (result.isComplexInt()) { 2671 IntRange R = GetValueRange(C, result.getComplexIntReal(), MaxWidth); 2672 IntRange I = GetValueRange(C, result.getComplexIntImag(), MaxWidth); 2673 return IntRange::join(R, I); 2674 } 2675 2676 // This can happen with lossless casts to intptr_t of "based" lvalues. 2677 // Assume it might use arbitrary bits. 2678 // FIXME: The only reason we need to pass the type in here is to get 2679 // the sign right on this one case. It would be nice if APValue 2680 // preserved this. 2681 assert(result.isLValue()); 2682 return IntRange(MaxWidth, Ty->isUnsignedIntegerOrEnumerationType()); 2683} 2684 2685/// Pseudo-evaluate the given integer expression, estimating the 2686/// range of values it might take. 2687/// 2688/// \param MaxWidth - the width to which the value will be truncated 2689IntRange GetExprRange(ASTContext &C, Expr *E, unsigned MaxWidth) { 2690 E = E->IgnoreParens(); 2691 2692 // Try a full evaluation first. 2693 Expr::EvalResult result; 2694 if (E->Evaluate(result, C)) 2695 return GetValueRange(C, result.Val, E->getType(), MaxWidth); 2696 2697 // I think we only want to look through implicit casts here; if the 2698 // user has an explicit widening cast, we should treat the value as 2699 // being of the new, wider type. 2700 if (ImplicitCastExpr *CE = dyn_cast<ImplicitCastExpr>(E)) { 2701 if (CE->getCastKind() == CK_NoOp) 2702 return GetExprRange(C, CE->getSubExpr(), MaxWidth); 2703 2704 IntRange OutputTypeRange = IntRange::forValueOfType(C, CE->getType()); 2705 2706 bool isIntegerCast = (CE->getCastKind() == CK_IntegralCast); 2707 2708 // Assume that non-integer casts can span the full range of the type. 2709 if (!isIntegerCast) 2710 return OutputTypeRange; 2711 2712 IntRange SubRange 2713 = GetExprRange(C, CE->getSubExpr(), 2714 std::min(MaxWidth, OutputTypeRange.Width)); 2715 2716 // Bail out if the subexpr's range is as wide as the cast type. 2717 if (SubRange.Width >= OutputTypeRange.Width) 2718 return OutputTypeRange; 2719 2720 // Otherwise, we take the smaller width, and we're non-negative if 2721 // either the output type or the subexpr is. 2722 return IntRange(SubRange.Width, 2723 SubRange.NonNegative || OutputTypeRange.NonNegative); 2724 } 2725 2726 if (ConditionalOperator *CO = dyn_cast<ConditionalOperator>(E)) { 2727 // If we can fold the condition, just take that operand. 2728 bool CondResult; 2729 if (CO->getCond()->EvaluateAsBooleanCondition(CondResult, C)) 2730 return GetExprRange(C, CondResult ? CO->getTrueExpr() 2731 : CO->getFalseExpr(), 2732 MaxWidth); 2733 2734 // Otherwise, conservatively merge. 2735 IntRange L = GetExprRange(C, CO->getTrueExpr(), MaxWidth); 2736 IntRange R = GetExprRange(C, CO->getFalseExpr(), MaxWidth); 2737 return IntRange::join(L, R); 2738 } 2739 2740 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) { 2741 switch (BO->getOpcode()) { 2742 2743 // Boolean-valued operations are single-bit and positive. 2744 case BO_LAnd: 2745 case BO_LOr: 2746 case BO_LT: 2747 case BO_GT: 2748 case BO_LE: 2749 case BO_GE: 2750 case BO_EQ: 2751 case BO_NE: 2752 return IntRange::forBoolType(); 2753 2754 // The type of the assignments is the type of the LHS, so the RHS 2755 // is not necessarily the same type. 2756 case BO_MulAssign: 2757 case BO_DivAssign: 2758 case BO_RemAssign: 2759 case BO_AddAssign: 2760 case BO_SubAssign: 2761 case BO_XorAssign: 2762 case BO_OrAssign: 2763 // TODO: bitfields? 2764 return IntRange::forValueOfType(C, E->getType()); 2765 2766 // Simple assignments just pass through the RHS, which will have 2767 // been coerced to the LHS type. 2768 case BO_Assign: 2769 // TODO: bitfields? 2770 return GetExprRange(C, BO->getRHS(), MaxWidth); 2771 2772 // Operations with opaque sources are black-listed. 2773 case BO_PtrMemD: 2774 case BO_PtrMemI: 2775 return IntRange::forValueOfType(C, E->getType()); 2776 2777 // Bitwise-and uses the *infinum* of the two source ranges. 2778 case BO_And: 2779 case BO_AndAssign: 2780 return IntRange::meet(GetExprRange(C, BO->getLHS(), MaxWidth), 2781 GetExprRange(C, BO->getRHS(), MaxWidth)); 2782 2783 // Left shift gets black-listed based on a judgement call. 2784 case BO_Shl: 2785 // ...except that we want to treat '1 << (blah)' as logically 2786 // positive. It's an important idiom. 2787 if (IntegerLiteral *I 2788 = dyn_cast<IntegerLiteral>(BO->getLHS()->IgnoreParenCasts())) { 2789 if (I->getValue() == 1) { 2790 IntRange R = IntRange::forValueOfType(C, E->getType()); 2791 return IntRange(R.Width, /*NonNegative*/ true); 2792 } 2793 } 2794 // fallthrough 2795 2796 case BO_ShlAssign: 2797 return IntRange::forValueOfType(C, E->getType()); 2798 2799 // Right shift by a constant can narrow its left argument. 2800 case BO_Shr: 2801 case BO_ShrAssign: { 2802 IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth); 2803 2804 // If the shift amount is a positive constant, drop the width by 2805 // that much. 2806 llvm::APSInt shift; 2807 if (BO->getRHS()->isIntegerConstantExpr(shift, C) && 2808 shift.isNonNegative()) { 2809 unsigned zext = shift.getZExtValue(); 2810 if (zext >= L.Width) 2811 L.Width = (L.NonNegative ? 0 : 1); 2812 else 2813 L.Width -= zext; 2814 } 2815 2816 return L; 2817 } 2818 2819 // Comma acts as its right operand. 2820 case BO_Comma: 2821 return GetExprRange(C, BO->getRHS(), MaxWidth); 2822 2823 // Black-list pointer subtractions. 2824 case BO_Sub: 2825 if (BO->getLHS()->getType()->isPointerType()) 2826 return IntRange::forValueOfType(C, E->getType()); 2827 break; 2828 2829 // The width of a division result is mostly determined by the size 2830 // of the LHS. 2831 case BO_Div: { 2832 // Don't 'pre-truncate' the operands. 2833 unsigned opWidth = C.getIntWidth(E->getType()); 2834 IntRange L = GetExprRange(C, BO->getLHS(), opWidth); 2835 2836 // If the divisor is constant, use that. 2837 llvm::APSInt divisor; 2838 if (BO->getRHS()->isIntegerConstantExpr(divisor, C)) { 2839 unsigned log2 = divisor.logBase2(); // floor(log_2(divisor)) 2840 if (log2 >= L.Width) 2841 L.Width = (L.NonNegative ? 0 : 1); 2842 else 2843 L.Width = std::min(L.Width - log2, MaxWidth); 2844 return L; 2845 } 2846 2847 // Otherwise, just use the LHS's width. 2848 IntRange R = GetExprRange(C, BO->getRHS(), opWidth); 2849 return IntRange(L.Width, L.NonNegative && R.NonNegative); 2850 } 2851 2852 // The result of a remainder can't be larger than the result of 2853 // either side. 2854 case BO_Rem: { 2855 // Don't 'pre-truncate' the operands. 2856 unsigned opWidth = C.getIntWidth(E->getType()); 2857 IntRange L = GetExprRange(C, BO->getLHS(), opWidth); 2858 IntRange R = GetExprRange(C, BO->getRHS(), opWidth); 2859 2860 IntRange meet = IntRange::meet(L, R); 2861 meet.Width = std::min(meet.Width, MaxWidth); 2862 return meet; 2863 } 2864 2865 // The default behavior is okay for these. 2866 case BO_Mul: 2867 case BO_Add: 2868 case BO_Xor: 2869 case BO_Or: 2870 break; 2871 } 2872 2873 // The default case is to treat the operation as if it were closed 2874 // on the narrowest type that encompasses both operands. 2875 IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth); 2876 IntRange R = GetExprRange(C, BO->getRHS(), MaxWidth); 2877 return IntRange::join(L, R); 2878 } 2879 2880 if (UnaryOperator *UO = dyn_cast<UnaryOperator>(E)) { 2881 switch (UO->getOpcode()) { 2882 // Boolean-valued operations are white-listed. 2883 case UO_LNot: 2884 return IntRange::forBoolType(); 2885 2886 // Operations with opaque sources are black-listed. 2887 case UO_Deref: 2888 case UO_AddrOf: // should be impossible 2889 return IntRange::forValueOfType(C, E->getType()); 2890 2891 default: 2892 return GetExprRange(C, UO->getSubExpr(), MaxWidth); 2893 } 2894 } 2895 2896 if (dyn_cast<OffsetOfExpr>(E)) { 2897 IntRange::forValueOfType(C, E->getType()); 2898 } 2899 2900 FieldDecl *BitField = E->getBitField(); 2901 if (BitField) { 2902 llvm::APSInt BitWidthAP = BitField->getBitWidth()->EvaluateAsInt(C); 2903 unsigned BitWidth = BitWidthAP.getZExtValue(); 2904 2905 return IntRange(BitWidth, 2906 BitField->getType()->isUnsignedIntegerOrEnumerationType()); 2907 } 2908 2909 return IntRange::forValueOfType(C, E->getType()); 2910} 2911 2912IntRange GetExprRange(ASTContext &C, Expr *E) { 2913 return GetExprRange(C, E, C.getIntWidth(E->getType())); 2914} 2915 2916/// Checks whether the given value, which currently has the given 2917/// source semantics, has the same value when coerced through the 2918/// target semantics. 2919bool IsSameFloatAfterCast(const llvm::APFloat &value, 2920 const llvm::fltSemantics &Src, 2921 const llvm::fltSemantics &Tgt) { 2922 llvm::APFloat truncated = value; 2923 2924 bool ignored; 2925 truncated.convert(Src, llvm::APFloat::rmNearestTiesToEven, &ignored); 2926 truncated.convert(Tgt, llvm::APFloat::rmNearestTiesToEven, &ignored); 2927 2928 return truncated.bitwiseIsEqual(value); 2929} 2930 2931/// Checks whether the given value, which currently has the given 2932/// source semantics, has the same value when coerced through the 2933/// target semantics. 2934/// 2935/// The value might be a vector of floats (or a complex number). 2936bool IsSameFloatAfterCast(const APValue &value, 2937 const llvm::fltSemantics &Src, 2938 const llvm::fltSemantics &Tgt) { 2939 if (value.isFloat()) 2940 return IsSameFloatAfterCast(value.getFloat(), Src, Tgt); 2941 2942 if (value.isVector()) { 2943 for (unsigned i = 0, e = value.getVectorLength(); i != e; ++i) 2944 if (!IsSameFloatAfterCast(value.getVectorElt(i), Src, Tgt)) 2945 return false; 2946 return true; 2947 } 2948 2949 assert(value.isComplexFloat()); 2950 return (IsSameFloatAfterCast(value.getComplexFloatReal(), Src, Tgt) && 2951 IsSameFloatAfterCast(value.getComplexFloatImag(), Src, Tgt)); 2952} 2953 2954void AnalyzeImplicitConversions(Sema &S, Expr *E, SourceLocation CC); 2955 2956static bool IsZero(Sema &S, Expr *E) { 2957 // Suppress cases where we are comparing against an enum constant. 2958 if (const DeclRefExpr *DR = 2959 dyn_cast<DeclRefExpr>(E->IgnoreParenImpCasts())) 2960 if (isa<EnumConstantDecl>(DR->getDecl())) 2961 return false; 2962 2963 // Suppress cases where the '0' value is expanded from a macro. 2964 if (E->getLocStart().isMacroID()) 2965 return false; 2966 2967 llvm::APSInt Value; 2968 return E->isIntegerConstantExpr(Value, S.Context) && Value == 0; 2969} 2970 2971static bool HasEnumType(Expr *E) { 2972 // Strip off implicit integral promotions. 2973 while (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(E)) { 2974 if (ICE->getCastKind() != CK_IntegralCast && 2975 ICE->getCastKind() != CK_NoOp) 2976 break; 2977 E = ICE->getSubExpr(); 2978 } 2979 2980 return E->getType()->isEnumeralType(); 2981} 2982 2983void CheckTrivialUnsignedComparison(Sema &S, BinaryOperator *E) { 2984 BinaryOperatorKind op = E->getOpcode(); 2985 if (E->isValueDependent()) 2986 return; 2987 2988 if (op == BO_LT && IsZero(S, E->getRHS())) { 2989 S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison) 2990 << "< 0" << "false" << HasEnumType(E->getLHS()) 2991 << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); 2992 } else if (op == BO_GE && IsZero(S, E->getRHS())) { 2993 S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison) 2994 << ">= 0" << "true" << HasEnumType(E->getLHS()) 2995 << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); 2996 } else if (op == BO_GT && IsZero(S, E->getLHS())) { 2997 S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison) 2998 << "0 >" << "false" << HasEnumType(E->getRHS()) 2999 << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); 3000 } else if (op == BO_LE && IsZero(S, E->getLHS())) { 3001 S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison) 3002 << "0 <=" << "true" << HasEnumType(E->getRHS()) 3003 << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); 3004 } 3005} 3006 3007/// Analyze the operands of the given comparison. Implements the 3008/// fallback case from AnalyzeComparison. 3009void AnalyzeImpConvsInComparison(Sema &S, BinaryOperator *E) { 3010 AnalyzeImplicitConversions(S, E->getLHS(), E->getOperatorLoc()); 3011 AnalyzeImplicitConversions(S, E->getRHS(), E->getOperatorLoc()); 3012} 3013 3014/// \brief Implements -Wsign-compare. 3015/// 3016/// \param lex the left-hand expression 3017/// \param rex the right-hand expression 3018/// \param OpLoc the location of the joining operator 3019/// \param BinOpc binary opcode or 0 3020void AnalyzeComparison(Sema &S, BinaryOperator *E) { 3021 // The type the comparison is being performed in. 3022 QualType T = E->getLHS()->getType(); 3023 assert(S.Context.hasSameUnqualifiedType(T, E->getRHS()->getType()) 3024 && "comparison with mismatched types"); 3025 3026 // We don't do anything special if this isn't an unsigned integral 3027 // comparison: we're only interested in integral comparisons, and 3028 // signed comparisons only happen in cases we don't care to warn about. 3029 // 3030 // We also don't care about value-dependent expressions or expressions 3031 // whose result is a constant. 3032 if (!T->hasUnsignedIntegerRepresentation() 3033 || E->isValueDependent() || E->isIntegerConstantExpr(S.Context)) 3034 return AnalyzeImpConvsInComparison(S, E); 3035 3036 Expr *lex = E->getLHS()->IgnoreParenImpCasts(); 3037 Expr *rex = E->getRHS()->IgnoreParenImpCasts(); 3038 3039 // Check to see if one of the (unmodified) operands is of different 3040 // signedness. 3041 Expr *signedOperand, *unsignedOperand; 3042 if (lex->getType()->hasSignedIntegerRepresentation()) { 3043 assert(!rex->getType()->hasSignedIntegerRepresentation() && 3044 "unsigned comparison between two signed integer expressions?"); 3045 signedOperand = lex; 3046 unsignedOperand = rex; 3047 } else if (rex->getType()->hasSignedIntegerRepresentation()) { 3048 signedOperand = rex; 3049 unsignedOperand = lex; 3050 } else { 3051 CheckTrivialUnsignedComparison(S, E); 3052 return AnalyzeImpConvsInComparison(S, E); 3053 } 3054 3055 // Otherwise, calculate the effective range of the signed operand. 3056 IntRange signedRange = GetExprRange(S.Context, signedOperand); 3057 3058 // Go ahead and analyze implicit conversions in the operands. Note 3059 // that we skip the implicit conversions on both sides. 3060 AnalyzeImplicitConversions(S, lex, E->getOperatorLoc()); 3061 AnalyzeImplicitConversions(S, rex, E->getOperatorLoc()); 3062 3063 // If the signed range is non-negative, -Wsign-compare won't fire, 3064 // but we should still check for comparisons which are always true 3065 // or false. 3066 if (signedRange.NonNegative) 3067 return CheckTrivialUnsignedComparison(S, E); 3068 3069 // For (in)equality comparisons, if the unsigned operand is a 3070 // constant which cannot collide with a overflowed signed operand, 3071 // then reinterpreting the signed operand as unsigned will not 3072 // change the result of the comparison. 3073 if (E->isEqualityOp()) { 3074 unsigned comparisonWidth = S.Context.getIntWidth(T); 3075 IntRange unsignedRange = GetExprRange(S.Context, unsignedOperand); 3076 3077 // We should never be unable to prove that the unsigned operand is 3078 // non-negative. 3079 assert(unsignedRange.NonNegative && "unsigned range includes negative?"); 3080 3081 if (unsignedRange.Width < comparisonWidth) 3082 return; 3083 } 3084 3085 S.Diag(E->getOperatorLoc(), diag::warn_mixed_sign_comparison) 3086 << lex->getType() << rex->getType() 3087 << lex->getSourceRange() << rex->getSourceRange(); 3088} 3089 3090/// Analyzes an attempt to assign the given value to a bitfield. 3091/// 3092/// Returns true if there was something fishy about the attempt. 3093bool AnalyzeBitFieldAssignment(Sema &S, FieldDecl *Bitfield, Expr *Init, 3094 SourceLocation InitLoc) { 3095 assert(Bitfield->isBitField()); 3096 if (Bitfield->isInvalidDecl()) 3097 return false; 3098 3099 // White-list bool bitfields. 3100 if (Bitfield->getType()->isBooleanType()) 3101 return false; 3102 3103 // Ignore value- or type-dependent expressions. 3104 if (Bitfield->getBitWidth()->isValueDependent() || 3105 Bitfield->getBitWidth()->isTypeDependent() || 3106 Init->isValueDependent() || 3107 Init->isTypeDependent()) 3108 return false; 3109 3110 Expr *OriginalInit = Init->IgnoreParenImpCasts(); 3111 3112 llvm::APSInt Width(32); 3113 Expr::EvalResult InitValue; 3114 if (!Bitfield->getBitWidth()->isIntegerConstantExpr(Width, S.Context) || 3115 !OriginalInit->Evaluate(InitValue, S.Context) || 3116 !InitValue.Val.isInt()) 3117 return false; 3118 3119 const llvm::APSInt &Value = InitValue.Val.getInt(); 3120 unsigned OriginalWidth = Value.getBitWidth(); 3121 unsigned FieldWidth = Width.getZExtValue(); 3122 3123 if (OriginalWidth <= FieldWidth) 3124 return false; 3125 3126 llvm::APSInt TruncatedValue = Value.trunc(FieldWidth); 3127 3128 // It's fairly common to write values into signed bitfields 3129 // that, if sign-extended, would end up becoming a different 3130 // value. We don't want to warn about that. 3131 if (Value.isSigned() && Value.isNegative()) 3132 TruncatedValue = TruncatedValue.sext(OriginalWidth); 3133 else 3134 TruncatedValue = TruncatedValue.zext(OriginalWidth); 3135 3136 if (Value == TruncatedValue) 3137 return false; 3138 3139 std::string PrettyValue = Value.toString(10); 3140 std::string PrettyTrunc = TruncatedValue.toString(10); 3141 3142 S.Diag(InitLoc, diag::warn_impcast_bitfield_precision_constant) 3143 << PrettyValue << PrettyTrunc << OriginalInit->getType() 3144 << Init->getSourceRange(); 3145 3146 return true; 3147} 3148 3149/// Analyze the given simple or compound assignment for warning-worthy 3150/// operations. 3151void AnalyzeAssignment(Sema &S, BinaryOperator *E) { 3152 // Just recurse on the LHS. 3153 AnalyzeImplicitConversions(S, E->getLHS(), E->getOperatorLoc()); 3154 3155 // We want to recurse on the RHS as normal unless we're assigning to 3156 // a bitfield. 3157 if (FieldDecl *Bitfield = E->getLHS()->getBitField()) { 3158 if (AnalyzeBitFieldAssignment(S, Bitfield, E->getRHS(), 3159 E->getOperatorLoc())) { 3160 // Recurse, ignoring any implicit conversions on the RHS. 3161 return AnalyzeImplicitConversions(S, E->getRHS()->IgnoreParenImpCasts(), 3162 E->getOperatorLoc()); 3163 } 3164 } 3165 3166 AnalyzeImplicitConversions(S, E->getRHS(), E->getOperatorLoc()); 3167} 3168 3169/// Diagnose an implicit cast; purely a helper for CheckImplicitConversion. 3170void DiagnoseImpCast(Sema &S, Expr *E, QualType SourceType, QualType T, 3171 SourceLocation CContext, unsigned diag) { 3172 S.Diag(E->getExprLoc(), diag) 3173 << SourceType << T << E->getSourceRange() << SourceRange(CContext); 3174} 3175 3176/// Diagnose an implicit cast; purely a helper for CheckImplicitConversion. 3177void DiagnoseImpCast(Sema &S, Expr *E, QualType T, SourceLocation CContext, 3178 unsigned diag) { 3179 DiagnoseImpCast(S, E, E->getType(), T, CContext, diag); 3180} 3181 3182/// Diagnose an implicit cast from a literal expression. Also attemps to supply 3183/// fixit hints when the cast wouldn't lose information to simply write the 3184/// expression with the expected type. 3185void DiagnoseFloatingLiteralImpCast(Sema &S, FloatingLiteral *FL, QualType T, 3186 SourceLocation CContext) { 3187 // Emit the primary warning first, then try to emit a fixit hint note if 3188 // reasonable. 3189 S.Diag(FL->getExprLoc(), diag::warn_impcast_literal_float_to_integer) 3190 << FL->getType() << T << FL->getSourceRange() << SourceRange(CContext); 3191 3192 const llvm::APFloat &Value = FL->getValue(); 3193 3194 // Don't attempt to fix PPC double double literals. 3195 if (&Value.getSemantics() == &llvm::APFloat::PPCDoubleDouble) 3196 return; 3197 3198 // Try to convert this exactly to an integer. 3199 bool isExact = false; 3200 llvm::APSInt IntegerValue(S.Context.getIntWidth(T), 3201 T->hasUnsignedIntegerRepresentation()); 3202 if (Value.convertToInteger(IntegerValue, 3203 llvm::APFloat::rmTowardZero, &isExact) 3204 != llvm::APFloat::opOK || !isExact) 3205 return; 3206 3207 std::string LiteralValue = IntegerValue.toString(10); 3208 S.Diag(FL->getExprLoc(), diag::note_fix_integral_float_as_integer) 3209 << FixItHint::CreateReplacement(FL->getSourceRange(), LiteralValue); 3210} 3211 3212std::string PrettyPrintInRange(const llvm::APSInt &Value, IntRange Range) { 3213 if (!Range.Width) return "0"; 3214 3215 llvm::APSInt ValueInRange = Value; 3216 ValueInRange.setIsSigned(!Range.NonNegative); 3217 ValueInRange = ValueInRange.trunc(Range.Width); 3218 return ValueInRange.toString(10); 3219} 3220 3221static bool isFromSystemMacro(Sema &S, SourceLocation loc) { 3222 SourceManager &smgr = S.Context.getSourceManager(); 3223 return loc.isMacroID() && smgr.isInSystemHeader(smgr.getSpellingLoc(loc)); 3224} 3225 3226void CheckImplicitConversion(Sema &S, Expr *E, QualType T, 3227 SourceLocation CC, bool *ICContext = 0) { 3228 if (E->isTypeDependent() || E->isValueDependent()) return; 3229 3230 const Type *Source = S.Context.getCanonicalType(E->getType()).getTypePtr(); 3231 const Type *Target = S.Context.getCanonicalType(T).getTypePtr(); 3232 if (Source == Target) return; 3233 if (Target->isDependentType()) return; 3234 3235 // If the conversion context location is invalid don't complain. We also 3236 // don't want to emit a warning if the issue occurs from the expansion of 3237 // a system macro. The problem is that 'getSpellingLoc()' is slow, so we 3238 // delay this check as long as possible. Once we detect we are in that 3239 // scenario, we just return. 3240 if (CC.isInvalid()) 3241 return; 3242 3243 // Never diagnose implicit casts to bool. 3244 if (Target->isSpecificBuiltinType(BuiltinType::Bool)) 3245 return; 3246 3247 // Strip vector types. 3248 if (isa<VectorType>(Source)) { 3249 if (!isa<VectorType>(Target)) { 3250 if (isFromSystemMacro(S, CC)) 3251 return; 3252 return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_vector_scalar); 3253 } 3254 3255 // If the vector cast is cast between two vectors of the same size, it is 3256 // a bitcast, not a conversion. 3257 if (S.Context.getTypeSize(Source) == S.Context.getTypeSize(Target)) 3258 return; 3259 3260 Source = cast<VectorType>(Source)->getElementType().getTypePtr(); 3261 Target = cast<VectorType>(Target)->getElementType().getTypePtr(); 3262 } 3263 3264 // Strip complex types. 3265 if (isa<ComplexType>(Source)) { 3266 if (!isa<ComplexType>(Target)) { 3267 if (isFromSystemMacro(S, CC)) 3268 return; 3269 3270 return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_complex_scalar); 3271 } 3272 3273 Source = cast<ComplexType>(Source)->getElementType().getTypePtr(); 3274 Target = cast<ComplexType>(Target)->getElementType().getTypePtr(); 3275 } 3276 3277 const BuiltinType *SourceBT = dyn_cast<BuiltinType>(Source); 3278 const BuiltinType *TargetBT = dyn_cast<BuiltinType>(Target); 3279 3280 // If the source is floating point... 3281 if (SourceBT && SourceBT->isFloatingPoint()) { 3282 // ...and the target is floating point... 3283 if (TargetBT && TargetBT->isFloatingPoint()) { 3284 // ...then warn if we're dropping FP rank. 3285 3286 // Builtin FP kinds are ordered by increasing FP rank. 3287 if (SourceBT->getKind() > TargetBT->getKind()) { 3288 // Don't warn about float constants that are precisely 3289 // representable in the target type. 3290 Expr::EvalResult result; 3291 if (E->Evaluate(result, S.Context)) { 3292 // Value might be a float, a float vector, or a float complex. 3293 if (IsSameFloatAfterCast(result.Val, 3294 S.Context.getFloatTypeSemantics(QualType(TargetBT, 0)), 3295 S.Context.getFloatTypeSemantics(QualType(SourceBT, 0)))) 3296 return; 3297 } 3298 3299 if (isFromSystemMacro(S, CC)) 3300 return; 3301 3302 DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_float_precision); 3303 } 3304 return; 3305 } 3306 3307 // If the target is integral, always warn. 3308 if ((TargetBT && TargetBT->isInteger())) { 3309 if (isFromSystemMacro(S, CC)) 3310 return; 3311 3312 Expr *InnerE = E->IgnoreParenImpCasts(); 3313 // We also want to warn on, e.g., "int i = -1.234" 3314 if (UnaryOperator *UOp = dyn_cast<UnaryOperator>(InnerE)) 3315 if (UOp->getOpcode() == UO_Minus || UOp->getOpcode() == UO_Plus) 3316 InnerE = UOp->getSubExpr()->IgnoreParenImpCasts(); 3317 3318 if (FloatingLiteral *FL = dyn_cast<FloatingLiteral>(InnerE)) { 3319 DiagnoseFloatingLiteralImpCast(S, FL, T, CC); 3320 } else { 3321 DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_float_integer); 3322 } 3323 } 3324 3325 return; 3326 } 3327 3328 if (!Source->isIntegerType() || !Target->isIntegerType()) 3329 return; 3330 3331 if ((E->isNullPointerConstant(S.Context, Expr::NPC_ValueDependentIsNotNull) 3332 == Expr::NPCK_GNUNull) && Target->isIntegerType()) { 3333 S.Diag(E->getExprLoc(), diag::warn_impcast_null_pointer_to_integer) 3334 << E->getSourceRange() << clang::SourceRange(CC); 3335 return; 3336 } 3337 3338 IntRange SourceRange = GetExprRange(S.Context, E); 3339 IntRange TargetRange = IntRange::forTargetOfCanonicalType(S.Context, Target); 3340 3341 if (SourceRange.Width > TargetRange.Width) { 3342 // If the source is a constant, use a default-on diagnostic. 3343 // TODO: this should happen for bitfield stores, too. 3344 llvm::APSInt Value(32); 3345 if (E->isIntegerConstantExpr(Value, S.Context)) { 3346 if (isFromSystemMacro(S, CC)) 3347 return; 3348 3349 std::string PrettySourceValue = Value.toString(10); 3350 std::string PrettyTargetValue = PrettyPrintInRange(Value, TargetRange); 3351 3352 S.Diag(E->getExprLoc(), diag::warn_impcast_integer_precision_constant) 3353 << PrettySourceValue << PrettyTargetValue 3354 << E->getType() << T << E->getSourceRange() << clang::SourceRange(CC); 3355 return; 3356 } 3357 3358 // People want to build with -Wshorten-64-to-32 and not -Wconversion. 3359 if (isFromSystemMacro(S, CC)) 3360 return; 3361 3362 if (SourceRange.Width == 64 && TargetRange.Width == 32) 3363 return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_integer_64_32); 3364 return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_integer_precision); 3365 } 3366 3367 if ((TargetRange.NonNegative && !SourceRange.NonNegative) || 3368 (!TargetRange.NonNegative && SourceRange.NonNegative && 3369 SourceRange.Width == TargetRange.Width)) { 3370 3371 if (isFromSystemMacro(S, CC)) 3372 return; 3373 3374 unsigned DiagID = diag::warn_impcast_integer_sign; 3375 3376 // Traditionally, gcc has warned about this under -Wsign-compare. 3377 // We also want to warn about it in -Wconversion. 3378 // So if -Wconversion is off, use a completely identical diagnostic 3379 // in the sign-compare group. 3380 // The conditional-checking code will 3381 if (ICContext) { 3382 DiagID = diag::warn_impcast_integer_sign_conditional; 3383 *ICContext = true; 3384 } 3385 3386 return DiagnoseImpCast(S, E, T, CC, DiagID); 3387 } 3388 3389 // Diagnose conversions between different enumeration types. 3390 // In C, we pretend that the type of an EnumConstantDecl is its enumeration 3391 // type, to give us better diagnostics. 3392 QualType SourceType = E->getType(); 3393 if (!S.getLangOptions().CPlusPlus) { 3394 if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) 3395 if (EnumConstantDecl *ECD = dyn_cast<EnumConstantDecl>(DRE->getDecl())) { 3396 EnumDecl *Enum = cast<EnumDecl>(ECD->getDeclContext()); 3397 SourceType = S.Context.getTypeDeclType(Enum); 3398 Source = S.Context.getCanonicalType(SourceType).getTypePtr(); 3399 } 3400 } 3401 3402 if (const EnumType *SourceEnum = Source->getAs<EnumType>()) 3403 if (const EnumType *TargetEnum = Target->getAs<EnumType>()) 3404 if ((SourceEnum->getDecl()->getIdentifier() || 3405 SourceEnum->getDecl()->getTypedefNameForAnonDecl()) && 3406 (TargetEnum->getDecl()->getIdentifier() || 3407 TargetEnum->getDecl()->getTypedefNameForAnonDecl()) && 3408 SourceEnum != TargetEnum) { 3409 if (isFromSystemMacro(S, CC)) 3410 return; 3411 3412 return DiagnoseImpCast(S, E, SourceType, T, CC, 3413 diag::warn_impcast_different_enum_types); 3414 } 3415 3416 return; 3417} 3418 3419void CheckConditionalOperator(Sema &S, ConditionalOperator *E, QualType T); 3420 3421void CheckConditionalOperand(Sema &S, Expr *E, QualType T, 3422 SourceLocation CC, bool &ICContext) { 3423 E = E->IgnoreParenImpCasts(); 3424 3425 if (isa<ConditionalOperator>(E)) 3426 return CheckConditionalOperator(S, cast<ConditionalOperator>(E), T); 3427 3428 AnalyzeImplicitConversions(S, E, CC); 3429 if (E->getType() != T) 3430 return CheckImplicitConversion(S, E, T, CC, &ICContext); 3431 return; 3432} 3433 3434void CheckConditionalOperator(Sema &S, ConditionalOperator *E, QualType T) { 3435 SourceLocation CC = E->getQuestionLoc(); 3436 3437 AnalyzeImplicitConversions(S, E->getCond(), CC); 3438 3439 bool Suspicious = false; 3440 CheckConditionalOperand(S, E->getTrueExpr(), T, CC, Suspicious); 3441 CheckConditionalOperand(S, E->getFalseExpr(), T, CC, Suspicious); 3442 3443 // If -Wconversion would have warned about either of the candidates 3444 // for a signedness conversion to the context type... 3445 if (!Suspicious) return; 3446 3447 // ...but it's currently ignored... 3448 if (S.Diags.getDiagnosticLevel(diag::warn_impcast_integer_sign_conditional, 3449 CC)) 3450 return; 3451 3452 // ...then check whether it would have warned about either of the 3453 // candidates for a signedness conversion to the condition type. 3454 if (E->getType() == T) return; 3455 3456 Suspicious = false; 3457 CheckImplicitConversion(S, E->getTrueExpr()->IgnoreParenImpCasts(), 3458 E->getType(), CC, &Suspicious); 3459 if (!Suspicious) 3460 CheckImplicitConversion(S, E->getFalseExpr()->IgnoreParenImpCasts(), 3461 E->getType(), CC, &Suspicious); 3462} 3463 3464/// AnalyzeImplicitConversions - Find and report any interesting 3465/// implicit conversions in the given expression. There are a couple 3466/// of competing diagnostics here, -Wconversion and -Wsign-compare. 3467void AnalyzeImplicitConversions(Sema &S, Expr *OrigE, SourceLocation CC) { 3468 QualType T = OrigE->getType(); 3469 Expr *E = OrigE->IgnoreParenImpCasts(); 3470 3471 // For conditional operators, we analyze the arguments as if they 3472 // were being fed directly into the output. 3473 if (isa<ConditionalOperator>(E)) { 3474 ConditionalOperator *CO = cast<ConditionalOperator>(E); 3475 CheckConditionalOperator(S, CO, T); 3476 return; 3477 } 3478 3479 // Go ahead and check any implicit conversions we might have skipped. 3480 // The non-canonical typecheck is just an optimization; 3481 // CheckImplicitConversion will filter out dead implicit conversions. 3482 if (E->getType() != T) 3483 CheckImplicitConversion(S, E, T, CC); 3484 3485 // Now continue drilling into this expression. 3486 3487 // Skip past explicit casts. 3488 if (isa<ExplicitCastExpr>(E)) { 3489 E = cast<ExplicitCastExpr>(E)->getSubExpr()->IgnoreParenImpCasts(); 3490 return AnalyzeImplicitConversions(S, E, CC); 3491 } 3492 3493 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) { 3494 // Do a somewhat different check with comparison operators. 3495 if (BO->isComparisonOp()) 3496 return AnalyzeComparison(S, BO); 3497 3498 // And with assignments and compound assignments. 3499 if (BO->isAssignmentOp()) 3500 return AnalyzeAssignment(S, BO); 3501 } 3502 3503 // These break the otherwise-useful invariant below. Fortunately, 3504 // we don't really need to recurse into them, because any internal 3505 // expressions should have been analyzed already when they were 3506 // built into statements. 3507 if (isa<StmtExpr>(E)) return; 3508 3509 // Don't descend into unevaluated contexts. 3510 if (isa<UnaryExprOrTypeTraitExpr>(E)) return; 3511 3512 // Now just recurse over the expression's children. 3513 CC = E->getExprLoc(); 3514 for (Stmt::child_range I = E->children(); I; ++I) 3515 AnalyzeImplicitConversions(S, cast<Expr>(*I), CC); 3516} 3517 3518} // end anonymous namespace 3519 3520/// Diagnoses "dangerous" implicit conversions within the given 3521/// expression (which is a full expression). Implements -Wconversion 3522/// and -Wsign-compare. 3523/// 3524/// \param CC the "context" location of the implicit conversion, i.e. 3525/// the most location of the syntactic entity requiring the implicit 3526/// conversion 3527void Sema::CheckImplicitConversions(Expr *E, SourceLocation CC) { 3528 // Don't diagnose in unevaluated contexts. 3529 if (ExprEvalContexts.back().Context == Sema::Unevaluated) 3530 return; 3531 3532 // Don't diagnose for value- or type-dependent expressions. 3533 if (E->isTypeDependent() || E->isValueDependent()) 3534 return; 3535 3536 // Check for array bounds violations in cases where the check isn't triggered 3537 // elsewhere for other Expr types (like BinaryOperators), e.g. when an 3538 // ArraySubscriptExpr is on the RHS of a variable initialization. 3539 CheckArrayAccess(E); 3540 3541 // This is not the right CC for (e.g.) a variable initialization. 3542 AnalyzeImplicitConversions(*this, E, CC); 3543} 3544 3545void Sema::CheckBitFieldInitialization(SourceLocation InitLoc, 3546 FieldDecl *BitField, 3547 Expr *Init) { 3548 (void) AnalyzeBitFieldAssignment(*this, BitField, Init, InitLoc); 3549} 3550 3551/// CheckParmsForFunctionDef - Check that the parameters of the given 3552/// function are appropriate for the definition of a function. This 3553/// takes care of any checks that cannot be performed on the 3554/// declaration itself, e.g., that the types of each of the function 3555/// parameters are complete. 3556bool Sema::CheckParmsForFunctionDef(ParmVarDecl **P, ParmVarDecl **PEnd, 3557 bool CheckParameterNames) { 3558 bool HasInvalidParm = false; 3559 for (; P != PEnd; ++P) { 3560 ParmVarDecl *Param = *P; 3561 3562 // C99 6.7.5.3p4: the parameters in a parameter type list in a 3563 // function declarator that is part of a function definition of 3564 // that function shall not have incomplete type. 3565 // 3566 // This is also C++ [dcl.fct]p6. 3567 if (!Param->isInvalidDecl() && 3568 RequireCompleteType(Param->getLocation(), Param->getType(), 3569 diag::err_typecheck_decl_incomplete_type)) { 3570 Param->setInvalidDecl(); 3571 HasInvalidParm = true; 3572 } 3573 3574 // C99 6.9.1p5: If the declarator includes a parameter type list, the 3575 // declaration of each parameter shall include an identifier. 3576 if (CheckParameterNames && 3577 Param->getIdentifier() == 0 && 3578 !Param->isImplicit() && 3579 !getLangOptions().CPlusPlus) 3580 Diag(Param->getLocation(), diag::err_parameter_name_omitted); 3581 3582 // C99 6.7.5.3p12: 3583 // If the function declarator is not part of a definition of that 3584 // function, parameters may have incomplete type and may use the [*] 3585 // notation in their sequences of declarator specifiers to specify 3586 // variable length array types. 3587 QualType PType = Param->getOriginalType(); 3588 if (const ArrayType *AT = Context.getAsArrayType(PType)) { 3589 if (AT->getSizeModifier() == ArrayType::Star) { 3590 // FIXME: This diagnosic should point the the '[*]' if source-location 3591 // information is added for it. 3592 Diag(Param->getLocation(), diag::err_array_star_in_function_definition); 3593 } 3594 } 3595 } 3596 3597 return HasInvalidParm; 3598} 3599 3600/// CheckCastAlign - Implements -Wcast-align, which warns when a 3601/// pointer cast increases the alignment requirements. 3602void Sema::CheckCastAlign(Expr *Op, QualType T, SourceRange TRange) { 3603 // This is actually a lot of work to potentially be doing on every 3604 // cast; don't do it if we're ignoring -Wcast_align (as is the default). 3605 if (getDiagnostics().getDiagnosticLevel(diag::warn_cast_align, 3606 TRange.getBegin()) 3607 == Diagnostic::Ignored) 3608 return; 3609 3610 // Ignore dependent types. 3611 if (T->isDependentType() || Op->getType()->isDependentType()) 3612 return; 3613 3614 // Require that the destination be a pointer type. 3615 const PointerType *DestPtr = T->getAs<PointerType>(); 3616 if (!DestPtr) return; 3617 3618 // If the destination has alignment 1, we're done. 3619 QualType DestPointee = DestPtr->getPointeeType(); 3620 if (DestPointee->isIncompleteType()) return; 3621 CharUnits DestAlign = Context.getTypeAlignInChars(DestPointee); 3622 if (DestAlign.isOne()) return; 3623 3624 // Require that the source be a pointer type. 3625 const PointerType *SrcPtr = Op->getType()->getAs<PointerType>(); 3626 if (!SrcPtr) return; 3627 QualType SrcPointee = SrcPtr->getPointeeType(); 3628 3629 // Whitelist casts from cv void*. We already implicitly 3630 // whitelisted casts to cv void*, since they have alignment 1. 3631 // Also whitelist casts involving incomplete types, which implicitly 3632 // includes 'void'. 3633 if (SrcPointee->isIncompleteType()) return; 3634 3635 CharUnits SrcAlign = Context.getTypeAlignInChars(SrcPointee); 3636 if (SrcAlign >= DestAlign) return; 3637 3638 Diag(TRange.getBegin(), diag::warn_cast_align) 3639 << Op->getType() << T 3640 << static_cast<unsigned>(SrcAlign.getQuantity()) 3641 << static_cast<unsigned>(DestAlign.getQuantity()) 3642 << TRange << Op->getSourceRange(); 3643} 3644 3645static const Type* getElementType(const Expr *BaseExpr) { 3646 const Type* EltType = BaseExpr->getType().getTypePtr(); 3647 if (EltType->isAnyPointerType()) 3648 return EltType->getPointeeType().getTypePtr(); 3649 else if (EltType->isArrayType()) 3650 return EltType->getBaseElementTypeUnsafe(); 3651 return EltType; 3652} 3653 3654/// \brief Check whether this array fits the idiom of a size-one tail padded 3655/// array member of a struct. 3656/// 3657/// We avoid emitting out-of-bounds access warnings for such arrays as they are 3658/// commonly used to emulate flexible arrays in C89 code. 3659static bool IsTailPaddedMemberArray(Sema &S, llvm::APInt Size, 3660 const NamedDecl *ND) { 3661 if (Size != 1 || !ND) return false; 3662 3663 const FieldDecl *FD = dyn_cast<FieldDecl>(ND); 3664 if (!FD) return false; 3665 3666 // Don't consider sizes resulting from macro expansions or template argument 3667 // substitution to form C89 tail-padded arrays. 3668 ConstantArrayTypeLoc TL = 3669 cast<ConstantArrayTypeLoc>(FD->getTypeSourceInfo()->getTypeLoc()); 3670 const Expr *SizeExpr = dyn_cast<IntegerLiteral>(TL.getSizeExpr()); 3671 if (!SizeExpr || SizeExpr->getExprLoc().isMacroID()) 3672 return false; 3673 3674 const RecordDecl *RD = dyn_cast<RecordDecl>(FD->getDeclContext()); 3675 if (!RD || !RD->isStruct()) 3676 return false; 3677 3678 // See if this is the last field decl in the record. 3679 const Decl *D = FD; 3680 while ((D = D->getNextDeclInContext())) 3681 if (isa<FieldDecl>(D)) 3682 return false; 3683 return true; 3684} 3685 3686void Sema::CheckArrayAccess(const Expr *BaseExpr, const Expr *IndexExpr, 3687 bool isSubscript, bool AllowOnePastEnd) { 3688 const Type* EffectiveType = getElementType(BaseExpr); 3689 BaseExpr = BaseExpr->IgnoreParenCasts(); 3690 IndexExpr = IndexExpr->IgnoreParenCasts(); 3691 3692 const ConstantArrayType *ArrayTy = 3693 Context.getAsConstantArrayType(BaseExpr->getType()); 3694 if (!ArrayTy) 3695 return; 3696 3697 if (IndexExpr->isValueDependent()) 3698 return; 3699 llvm::APSInt index; 3700 if (!IndexExpr->isIntegerConstantExpr(index, Context)) 3701 return; 3702 3703 const NamedDecl *ND = NULL; 3704 if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(BaseExpr)) 3705 ND = dyn_cast<NamedDecl>(DRE->getDecl()); 3706 if (const MemberExpr *ME = dyn_cast<MemberExpr>(BaseExpr)) 3707 ND = dyn_cast<NamedDecl>(ME->getMemberDecl()); 3708 3709 if (index.isUnsigned() || !index.isNegative()) { 3710 llvm::APInt size = ArrayTy->getSize(); 3711 if (!size.isStrictlyPositive()) 3712 return; 3713 3714 const Type* BaseType = getElementType(BaseExpr); 3715 if (!isSubscript && BaseType != EffectiveType) { 3716 // Make sure we're comparing apples to apples when comparing index to size 3717 uint64_t ptrarith_typesize = Context.getTypeSize(EffectiveType); 3718 uint64_t array_typesize = Context.getTypeSize(BaseType); 3719 // Handle ptrarith_typesize being zero, such as when casting to void* 3720 if (!ptrarith_typesize) ptrarith_typesize = 1; 3721 if (ptrarith_typesize != array_typesize) { 3722 // There's a cast to a different size type involved 3723 uint64_t ratio = array_typesize / ptrarith_typesize; 3724 // TODO: Be smarter about handling cases where array_typesize is not a 3725 // multiple of ptrarith_typesize 3726 if (ptrarith_typesize * ratio == array_typesize) 3727 size *= llvm::APInt(size.getBitWidth(), ratio); 3728 } 3729 } 3730 3731 if (size.getBitWidth() > index.getBitWidth()) 3732 index = index.sext(size.getBitWidth()); 3733 else if (size.getBitWidth() < index.getBitWidth()) 3734 size = size.sext(index.getBitWidth()); 3735 3736 // For array subscripting the index must be less than size, but for pointer 3737 // arithmetic also allow the index (offset) to be equal to size since 3738 // computing the next address after the end of the array is legal and 3739 // commonly done e.g. in C++ iterators and range-based for loops. 3740 if (AllowOnePastEnd ? index.sle(size) : index.slt(size)) 3741 return; 3742 3743 // Also don't warn for arrays of size 1 which are members of some 3744 // structure. These are often used to approximate flexible arrays in C89 3745 // code. 3746 if (IsTailPaddedMemberArray(*this, size, ND)) 3747 return; 3748 3749 unsigned DiagID = diag::warn_ptr_arith_exceeds_bounds; 3750 if (isSubscript) 3751 DiagID = diag::warn_array_index_exceeds_bounds; 3752 3753 DiagRuntimeBehavior(BaseExpr->getLocStart(), BaseExpr, 3754 PDiag(DiagID) << index.toString(10, true) 3755 << size.toString(10, true) 3756 << (unsigned)size.getLimitedValue(~0U) 3757 << IndexExpr->getSourceRange()); 3758 } else { 3759 unsigned DiagID = diag::warn_array_index_precedes_bounds; 3760 if (!isSubscript) { 3761 DiagID = diag::warn_ptr_arith_precedes_bounds; 3762 if (index.isNegative()) index = -index; 3763 } 3764 3765 DiagRuntimeBehavior(BaseExpr->getLocStart(), BaseExpr, 3766 PDiag(DiagID) << index.toString(10, true) 3767 << IndexExpr->getSourceRange()); 3768 } 3769 3770 if (ND) 3771 DiagRuntimeBehavior(ND->getLocStart(), BaseExpr, 3772 PDiag(diag::note_array_index_out_of_bounds) 3773 << ND->getDeclName()); 3774} 3775 3776void Sema::CheckArrayAccess(const Expr *expr) { 3777 int AllowOnePastEnd = 0; 3778 while (expr) { 3779 expr = expr->IgnoreParenImpCasts(); 3780 switch (expr->getStmtClass()) { 3781 case Stmt::ArraySubscriptExprClass: { 3782 const ArraySubscriptExpr *ASE = cast<ArraySubscriptExpr>(expr); 3783 CheckArrayAccess(ASE->getBase(), ASE->getIdx(), true, 3784 AllowOnePastEnd > 0); 3785 return; 3786 } 3787 case Stmt::UnaryOperatorClass: { 3788 // Only unwrap the * and & unary operators 3789 const UnaryOperator *UO = cast<UnaryOperator>(expr); 3790 expr = UO->getSubExpr(); 3791 switch (UO->getOpcode()) { 3792 case UO_AddrOf: 3793 AllowOnePastEnd++; 3794 break; 3795 case UO_Deref: 3796 AllowOnePastEnd--; 3797 break; 3798 default: 3799 return; 3800 } 3801 break; 3802 } 3803 case Stmt::ConditionalOperatorClass: { 3804 const ConditionalOperator *cond = cast<ConditionalOperator>(expr); 3805 if (const Expr *lhs = cond->getLHS()) 3806 CheckArrayAccess(lhs); 3807 if (const Expr *rhs = cond->getRHS()) 3808 CheckArrayAccess(rhs); 3809 return; 3810 } 3811 default: 3812 return; 3813 } 3814 } 3815} 3816 3817//===--- CHECK: Objective-C retain cycles ----------------------------------// 3818 3819namespace { 3820 struct RetainCycleOwner { 3821 RetainCycleOwner() : Variable(0), Indirect(false) {} 3822 VarDecl *Variable; 3823 SourceRange Range; 3824 SourceLocation Loc; 3825 bool Indirect; 3826 3827 void setLocsFrom(Expr *e) { 3828 Loc = e->getExprLoc(); 3829 Range = e->getSourceRange(); 3830 } 3831 }; 3832} 3833 3834/// Consider whether capturing the given variable can possibly lead to 3835/// a retain cycle. 3836static bool considerVariable(VarDecl *var, Expr *ref, RetainCycleOwner &owner) { 3837 // In ARC, it's captured strongly iff the variable has __strong 3838 // lifetime. In MRR, it's captured strongly if the variable is 3839 // __block and has an appropriate type. 3840 if (var->getType().getObjCLifetime() != Qualifiers::OCL_Strong) 3841 return false; 3842 3843 owner.Variable = var; 3844 owner.setLocsFrom(ref); 3845 return true; 3846} 3847 3848static bool findRetainCycleOwner(Expr *e, RetainCycleOwner &owner) { 3849 while (true) { 3850 e = e->IgnoreParens(); 3851 if (CastExpr *cast = dyn_cast<CastExpr>(e)) { 3852 switch (cast->getCastKind()) { 3853 case CK_BitCast: 3854 case CK_LValueBitCast: 3855 case CK_LValueToRValue: 3856 case CK_ARCReclaimReturnedObject: 3857 e = cast->getSubExpr(); 3858 continue; 3859 3860 case CK_GetObjCProperty: { 3861 // Bail out if this isn't a strong explicit property. 3862 const ObjCPropertyRefExpr *pre = cast->getSubExpr()->getObjCProperty(); 3863 if (pre->isImplicitProperty()) return false; 3864 ObjCPropertyDecl *property = pre->getExplicitProperty(); 3865 if (!(property->getPropertyAttributes() & 3866 (ObjCPropertyDecl::OBJC_PR_retain | 3867 ObjCPropertyDecl::OBJC_PR_copy | 3868 ObjCPropertyDecl::OBJC_PR_strong)) && 3869 !(property->getPropertyIvarDecl() && 3870 property->getPropertyIvarDecl()->getType() 3871 .getObjCLifetime() == Qualifiers::OCL_Strong)) 3872 return false; 3873 3874 owner.Indirect = true; 3875 e = const_cast<Expr*>(pre->getBase()); 3876 continue; 3877 } 3878 3879 default: 3880 return false; 3881 } 3882 } 3883 3884 if (ObjCIvarRefExpr *ref = dyn_cast<ObjCIvarRefExpr>(e)) { 3885 ObjCIvarDecl *ivar = ref->getDecl(); 3886 if (ivar->getType().getObjCLifetime() != Qualifiers::OCL_Strong) 3887 return false; 3888 3889 // Try to find a retain cycle in the base. 3890 if (!findRetainCycleOwner(ref->getBase(), owner)) 3891 return false; 3892 3893 if (ref->isFreeIvar()) owner.setLocsFrom(ref); 3894 owner.Indirect = true; 3895 return true; 3896 } 3897 3898 if (DeclRefExpr *ref = dyn_cast<DeclRefExpr>(e)) { 3899 VarDecl *var = dyn_cast<VarDecl>(ref->getDecl()); 3900 if (!var) return false; 3901 return considerVariable(var, ref, owner); 3902 } 3903 3904 if (BlockDeclRefExpr *ref = dyn_cast<BlockDeclRefExpr>(e)) { 3905 owner.Variable = ref->getDecl(); 3906 owner.setLocsFrom(ref); 3907 return true; 3908 } 3909 3910 if (MemberExpr *member = dyn_cast<MemberExpr>(e)) { 3911 if (member->isArrow()) return false; 3912 3913 // Don't count this as an indirect ownership. 3914 e = member->getBase(); 3915 continue; 3916 } 3917 3918 // Array ivars? 3919 3920 return false; 3921 } 3922} 3923 3924namespace { 3925 struct FindCaptureVisitor : EvaluatedExprVisitor<FindCaptureVisitor> { 3926 FindCaptureVisitor(ASTContext &Context, VarDecl *variable) 3927 : EvaluatedExprVisitor<FindCaptureVisitor>(Context), 3928 Variable(variable), Capturer(0) {} 3929 3930 VarDecl *Variable; 3931 Expr *Capturer; 3932 3933 void VisitDeclRefExpr(DeclRefExpr *ref) { 3934 if (ref->getDecl() == Variable && !Capturer) 3935 Capturer = ref; 3936 } 3937 3938 void VisitBlockDeclRefExpr(BlockDeclRefExpr *ref) { 3939 if (ref->getDecl() == Variable && !Capturer) 3940 Capturer = ref; 3941 } 3942 3943 void VisitObjCIvarRefExpr(ObjCIvarRefExpr *ref) { 3944 if (Capturer) return; 3945 Visit(ref->getBase()); 3946 if (Capturer && ref->isFreeIvar()) 3947 Capturer = ref; 3948 } 3949 3950 void VisitBlockExpr(BlockExpr *block) { 3951 // Look inside nested blocks 3952 if (block->getBlockDecl()->capturesVariable(Variable)) 3953 Visit(block->getBlockDecl()->getBody()); 3954 } 3955 }; 3956} 3957 3958/// Check whether the given argument is a block which captures a 3959/// variable. 3960static Expr *findCapturingExpr(Sema &S, Expr *e, RetainCycleOwner &owner) { 3961 assert(owner.Variable && owner.Loc.isValid()); 3962 3963 e = e->IgnoreParenCasts(); 3964 BlockExpr *block = dyn_cast<BlockExpr>(e); 3965 if (!block || !block->getBlockDecl()->capturesVariable(owner.Variable)) 3966 return 0; 3967 3968 FindCaptureVisitor visitor(S.Context, owner.Variable); 3969 visitor.Visit(block->getBlockDecl()->getBody()); 3970 return visitor.Capturer; 3971} 3972 3973static void diagnoseRetainCycle(Sema &S, Expr *capturer, 3974 RetainCycleOwner &owner) { 3975 assert(capturer); 3976 assert(owner.Variable && owner.Loc.isValid()); 3977 3978 S.Diag(capturer->getExprLoc(), diag::warn_arc_retain_cycle) 3979 << owner.Variable << capturer->getSourceRange(); 3980 S.Diag(owner.Loc, diag::note_arc_retain_cycle_owner) 3981 << owner.Indirect << owner.Range; 3982} 3983 3984/// Check for a keyword selector that starts with the word 'add' or 3985/// 'set'. 3986static bool isSetterLikeSelector(Selector sel) { 3987 if (sel.isUnarySelector()) return false; 3988 3989 StringRef str = sel.getNameForSlot(0); 3990 while (!str.empty() && str.front() == '_') str = str.substr(1); 3991 if (str.startswith("set") || str.startswith("add")) 3992 str = str.substr(3); 3993 else 3994 return false; 3995 3996 if (str.empty()) return true; 3997 return !islower(str.front()); 3998} 3999 4000/// Check a message send to see if it's likely to cause a retain cycle. 4001void Sema::checkRetainCycles(ObjCMessageExpr *msg) { 4002 // Only check instance methods whose selector looks like a setter. 4003 if (!msg->isInstanceMessage() || !isSetterLikeSelector(msg->getSelector())) 4004 return; 4005 4006 // Try to find a variable that the receiver is strongly owned by. 4007 RetainCycleOwner owner; 4008 if (msg->getReceiverKind() == ObjCMessageExpr::Instance) { 4009 if (!findRetainCycleOwner(msg->getInstanceReceiver(), owner)) 4010 return; 4011 } else { 4012 assert(msg->getReceiverKind() == ObjCMessageExpr::SuperInstance); 4013 owner.Variable = getCurMethodDecl()->getSelfDecl(); 4014 owner.Loc = msg->getSuperLoc(); 4015 owner.Range = msg->getSuperLoc(); 4016 } 4017 4018 // Check whether the receiver is captured by any of the arguments. 4019 for (unsigned i = 0, e = msg->getNumArgs(); i != e; ++i) 4020 if (Expr *capturer = findCapturingExpr(*this, msg->getArg(i), owner)) 4021 return diagnoseRetainCycle(*this, capturer, owner); 4022} 4023 4024/// Check a property assign to see if it's likely to cause a retain cycle. 4025void Sema::checkRetainCycles(Expr *receiver, Expr *argument) { 4026 RetainCycleOwner owner; 4027 if (!findRetainCycleOwner(receiver, owner)) 4028 return; 4029 4030 if (Expr *capturer = findCapturingExpr(*this, argument, owner)) 4031 diagnoseRetainCycle(*this, capturer, owner); 4032} 4033 4034bool Sema::checkUnsafeAssigns(SourceLocation Loc, 4035 QualType LHS, Expr *RHS) { 4036 Qualifiers::ObjCLifetime LT = LHS.getObjCLifetime(); 4037 if (LT != Qualifiers::OCL_Weak && LT != Qualifiers::OCL_ExplicitNone) 4038 return false; 4039 // strip off any implicit cast added to get to the one arc-specific 4040 while (ImplicitCastExpr *cast = dyn_cast<ImplicitCastExpr>(RHS)) { 4041 if (cast->getCastKind() == CK_ARCConsumeObject) { 4042 Diag(Loc, diag::warn_arc_retained_assign) 4043 << (LT == Qualifiers::OCL_ExplicitNone) 4044 << RHS->getSourceRange(); 4045 return true; 4046 } 4047 RHS = cast->getSubExpr(); 4048 } 4049 return false; 4050} 4051 4052void Sema::checkUnsafeExprAssigns(SourceLocation Loc, 4053 Expr *LHS, Expr *RHS) { 4054 QualType LHSType = LHS->getType(); 4055 if (checkUnsafeAssigns(Loc, LHSType, RHS)) 4056 return; 4057 Qualifiers::ObjCLifetime LT = LHSType.getObjCLifetime(); 4058 // FIXME. Check for other life times. 4059 if (LT != Qualifiers::OCL_None) 4060 return; 4061 4062 if (ObjCPropertyRefExpr *PRE = dyn_cast<ObjCPropertyRefExpr>(LHS)) { 4063 if (PRE->isImplicitProperty()) 4064 return; 4065 const ObjCPropertyDecl *PD = PRE->getExplicitProperty(); 4066 if (!PD) 4067 return; 4068 4069 unsigned Attributes = PD->getPropertyAttributes(); 4070 if (Attributes & ObjCPropertyDecl::OBJC_PR_assign) 4071 while (ImplicitCastExpr *cast = dyn_cast<ImplicitCastExpr>(RHS)) { 4072 if (cast->getCastKind() == CK_ARCConsumeObject) { 4073 Diag(Loc, diag::warn_arc_retained_property_assign) 4074 << RHS->getSourceRange(); 4075 return; 4076 } 4077 RHS = cast->getSubExpr(); 4078 } 4079 } 4080} 4081