SemaChecking.cpp revision 213786
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/Sema.h" 16#include "clang/Sema/SemaInternal.h" 17#include "clang/Sema/ScopeInfo.h" 18#include "clang/Analysis/Analyses/FormatString.h" 19#include "clang/AST/ASTContext.h" 20#include "clang/AST/CharUnits.h" 21#include "clang/AST/DeclCXX.h" 22#include "clang/AST/DeclObjC.h" 23#include "clang/AST/ExprCXX.h" 24#include "clang/AST/ExprObjC.h" 25#include "clang/AST/DeclObjC.h" 26#include "clang/AST/StmtCXX.h" 27#include "clang/AST/StmtObjC.h" 28#include "clang/Lex/LiteralSupport.h" 29#include "clang/Lex/Preprocessor.h" 30#include "llvm/ADT/BitVector.h" 31#include "llvm/ADT/STLExtras.h" 32#include "llvm/Support/raw_ostream.h" 33#include "clang/Basic/TargetBuiltins.h" 34#include "clang/Basic/TargetInfo.h" 35#include <limits> 36using namespace clang; 37using namespace sema; 38 39/// getLocationOfStringLiteralByte - Return a source location that points to the 40/// specified byte of the specified string literal. 41/// 42/// Strings are amazingly complex. They can be formed from multiple tokens and 43/// can have escape sequences in them in addition to the usual trigraph and 44/// escaped newline business. This routine handles this complexity. 45/// 46SourceLocation Sema::getLocationOfStringLiteralByte(const StringLiteral *SL, 47 unsigned ByteNo) const { 48 assert(!SL->isWide() && "This doesn't work for wide strings yet"); 49 50 // Loop over all of the tokens in this string until we find the one that 51 // contains the byte we're looking for. 52 unsigned TokNo = 0; 53 while (1) { 54 assert(TokNo < SL->getNumConcatenated() && "Invalid byte number!"); 55 SourceLocation StrTokLoc = SL->getStrTokenLoc(TokNo); 56 57 // Get the spelling of the string so that we can get the data that makes up 58 // the string literal, not the identifier for the macro it is potentially 59 // expanded through. 60 SourceLocation StrTokSpellingLoc = SourceMgr.getSpellingLoc(StrTokLoc); 61 62 // Re-lex the token to get its length and original spelling. 63 std::pair<FileID, unsigned> LocInfo = 64 SourceMgr.getDecomposedLoc(StrTokSpellingLoc); 65 bool Invalid = false; 66 llvm::StringRef Buffer = SourceMgr.getBufferData(LocInfo.first, &Invalid); 67 if (Invalid) 68 return StrTokSpellingLoc; 69 70 const char *StrData = Buffer.data()+LocInfo.second; 71 72 // Create a langops struct and enable trigraphs. This is sufficient for 73 // relexing tokens. 74 LangOptions LangOpts; 75 LangOpts.Trigraphs = true; 76 77 // Create a lexer starting at the beginning of this token. 78 Lexer TheLexer(StrTokSpellingLoc, LangOpts, Buffer.begin(), StrData, 79 Buffer.end()); 80 Token TheTok; 81 TheLexer.LexFromRawLexer(TheTok); 82 83 // Use the StringLiteralParser to compute the length of the string in bytes. 84 StringLiteralParser SLP(&TheTok, 1, PP, /*Complain=*/false); 85 unsigned TokNumBytes = SLP.GetStringLength(); 86 87 // If the byte is in this token, return the location of the byte. 88 if (ByteNo < TokNumBytes || 89 (ByteNo == TokNumBytes && TokNo == SL->getNumConcatenated())) { 90 unsigned Offset = 91 StringLiteralParser::getOffsetOfStringByte(TheTok, ByteNo, PP, 92 /*Complain=*/false); 93 94 // Now that we know the offset of the token in the spelling, use the 95 // preprocessor to get the offset in the original source. 96 return PP.AdvanceToTokenCharacter(StrTokLoc, Offset); 97 } 98 99 // Move to the next string token. 100 ++TokNo; 101 ByteNo -= TokNumBytes; 102 } 103} 104 105/// CheckablePrintfAttr - does a function call have a "printf" attribute 106/// and arguments that merit checking? 107bool Sema::CheckablePrintfAttr(const FormatAttr *Format, CallExpr *TheCall) { 108 if (Format->getType() == "printf") return true; 109 if (Format->getType() == "printf0") { 110 // printf0 allows null "format" string; if so don't check format/args 111 unsigned format_idx = Format->getFormatIdx() - 1; 112 // Does the index refer to the implicit object argument? 113 if (isa<CXXMemberCallExpr>(TheCall)) { 114 if (format_idx == 0) 115 return false; 116 --format_idx; 117 } 118 if (format_idx < TheCall->getNumArgs()) { 119 Expr *Format = TheCall->getArg(format_idx)->IgnoreParenCasts(); 120 if (!Format->isNullPointerConstant(Context, 121 Expr::NPC_ValueDependentIsNull)) 122 return true; 123 } 124 } 125 return false; 126} 127 128ExprResult 129Sema::CheckBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) { 130 ExprResult TheCallResult(Owned(TheCall)); 131 132 switch (BuiltinID) { 133 case Builtin::BI__builtin___CFStringMakeConstantString: 134 assert(TheCall->getNumArgs() == 1 && 135 "Wrong # arguments to builtin CFStringMakeConstantString"); 136 if (CheckObjCString(TheCall->getArg(0))) 137 return ExprError(); 138 break; 139 case Builtin::BI__builtin_stdarg_start: 140 case Builtin::BI__builtin_va_start: 141 if (SemaBuiltinVAStart(TheCall)) 142 return ExprError(); 143 break; 144 case Builtin::BI__builtin_isgreater: 145 case Builtin::BI__builtin_isgreaterequal: 146 case Builtin::BI__builtin_isless: 147 case Builtin::BI__builtin_islessequal: 148 case Builtin::BI__builtin_islessgreater: 149 case Builtin::BI__builtin_isunordered: 150 if (SemaBuiltinUnorderedCompare(TheCall)) 151 return ExprError(); 152 break; 153 case Builtin::BI__builtin_fpclassify: 154 if (SemaBuiltinFPClassification(TheCall, 6)) 155 return ExprError(); 156 break; 157 case Builtin::BI__builtin_isfinite: 158 case Builtin::BI__builtin_isinf: 159 case Builtin::BI__builtin_isinf_sign: 160 case Builtin::BI__builtin_isnan: 161 case Builtin::BI__builtin_isnormal: 162 if (SemaBuiltinFPClassification(TheCall, 1)) 163 return ExprError(); 164 break; 165 case Builtin::BI__builtin_return_address: 166 case Builtin::BI__builtin_frame_address: { 167 llvm::APSInt Result; 168 if (SemaBuiltinConstantArg(TheCall, 0, Result)) 169 return ExprError(); 170 break; 171 } 172 case Builtin::BI__builtin_eh_return_data_regno: { 173 llvm::APSInt Result; 174 if (SemaBuiltinConstantArg(TheCall, 0, Result)) 175 return ExprError(); 176 break; 177 } 178 case Builtin::BI__builtin_shufflevector: 179 return SemaBuiltinShuffleVector(TheCall); 180 // TheCall will be freed by the smart pointer here, but that's fine, since 181 // SemaBuiltinShuffleVector guts it, but then doesn't release it. 182 case Builtin::BI__builtin_prefetch: 183 if (SemaBuiltinPrefetch(TheCall)) 184 return ExprError(); 185 break; 186 case Builtin::BI__builtin_object_size: 187 if (SemaBuiltinObjectSize(TheCall)) 188 return ExprError(); 189 break; 190 case Builtin::BI__builtin_longjmp: 191 if (SemaBuiltinLongjmp(TheCall)) 192 return ExprError(); 193 break; 194 case Builtin::BI__sync_fetch_and_add: 195 case Builtin::BI__sync_fetch_and_sub: 196 case Builtin::BI__sync_fetch_and_or: 197 case Builtin::BI__sync_fetch_and_and: 198 case Builtin::BI__sync_fetch_and_xor: 199 case Builtin::BI__sync_add_and_fetch: 200 case Builtin::BI__sync_sub_and_fetch: 201 case Builtin::BI__sync_and_and_fetch: 202 case Builtin::BI__sync_or_and_fetch: 203 case Builtin::BI__sync_xor_and_fetch: 204 case Builtin::BI__sync_val_compare_and_swap: 205 case Builtin::BI__sync_bool_compare_and_swap: 206 case Builtin::BI__sync_lock_test_and_set: 207 case Builtin::BI__sync_lock_release: 208 return SemaBuiltinAtomicOverloaded(move(TheCallResult)); 209 } 210 211 // Since the target specific builtins for each arch overlap, only check those 212 // of the arch we are compiling for. 213 if (BuiltinID >= Builtin::FirstTSBuiltin) { 214 switch (Context.Target.getTriple().getArch()) { 215 case llvm::Triple::arm: 216 case llvm::Triple::thumb: 217 if (CheckARMBuiltinFunctionCall(BuiltinID, TheCall)) 218 return ExprError(); 219 break; 220 case llvm::Triple::x86: 221 case llvm::Triple::x86_64: 222 if (CheckX86BuiltinFunctionCall(BuiltinID, TheCall)) 223 return ExprError(); 224 break; 225 default: 226 break; 227 } 228 } 229 230 return move(TheCallResult); 231} 232 233bool Sema::CheckX86BuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) { 234 switch (BuiltinID) { 235 case X86::BI__builtin_ia32_palignr128: 236 case X86::BI__builtin_ia32_palignr: { 237 llvm::APSInt Result; 238 if (SemaBuiltinConstantArg(TheCall, 2, Result)) 239 return true; 240 break; 241 } 242 } 243 return false; 244} 245 246// Get the valid immediate range for the specified NEON type code. 247static unsigned RFT(unsigned t, bool shift = false) { 248 bool quad = t & 0x10; 249 250 switch (t & 0x7) { 251 case 0: // i8 252 return shift ? 7 : (8 << (int)quad) - 1; 253 case 1: // i16 254 return shift ? 15 : (4 << (int)quad) - 1; 255 case 2: // i32 256 return shift ? 31 : (2 << (int)quad) - 1; 257 case 3: // i64 258 return shift ? 63 : (1 << (int)quad) - 1; 259 case 4: // f32 260 assert(!shift && "cannot shift float types!"); 261 return (2 << (int)quad) - 1; 262 case 5: // poly8 263 assert(!shift && "cannot shift polynomial types!"); 264 return (8 << (int)quad) - 1; 265 case 6: // poly16 266 assert(!shift && "cannot shift polynomial types!"); 267 return (4 << (int)quad) - 1; 268 case 7: // float16 269 assert(!shift && "cannot shift float types!"); 270 return (4 << (int)quad) - 1; 271 } 272 return 0; 273} 274 275bool Sema::CheckARMBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) { 276 llvm::APSInt Result; 277 278 unsigned mask = 0; 279 unsigned TV = 0; 280 switch (BuiltinID) { 281#define GET_NEON_OVERLOAD_CHECK 282#include "clang/Basic/arm_neon.inc" 283#undef GET_NEON_OVERLOAD_CHECK 284 } 285 286 // For NEON intrinsics which are overloaded on vector element type, validate 287 // the immediate which specifies which variant to emit. 288 if (mask) { 289 unsigned ArgNo = TheCall->getNumArgs()-1; 290 if (SemaBuiltinConstantArg(TheCall, ArgNo, Result)) 291 return true; 292 293 TV = Result.getLimitedValue(32); 294 if ((TV > 31) || (mask & (1 << TV)) == 0) 295 return Diag(TheCall->getLocStart(), diag::err_invalid_neon_type_code) 296 << TheCall->getArg(ArgNo)->getSourceRange(); 297 } 298 299 // For NEON intrinsics which take an immediate value as part of the 300 // instruction, range check them here. 301 unsigned i = 0, l = 0, u = 0; 302 switch (BuiltinID) { 303 default: return false; 304 case ARM::BI__builtin_arm_ssat: i = 1; l = 1; u = 31; break; 305 case ARM::BI__builtin_arm_usat: i = 1; u = 31; break; 306 case ARM::BI__builtin_arm_vcvtr_f: 307 case ARM::BI__builtin_arm_vcvtr_d: i = 1; u = 1; break; 308#define GET_NEON_IMMEDIATE_CHECK 309#include "clang/Basic/arm_neon.inc" 310#undef GET_NEON_IMMEDIATE_CHECK 311 }; 312 313 // Check that the immediate argument is actually a constant. 314 if (SemaBuiltinConstantArg(TheCall, i, Result)) 315 return true; 316 317 // Range check against the upper/lower values for this isntruction. 318 unsigned Val = Result.getZExtValue(); 319 if (Val < l || Val > (u + l)) 320 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 321 << l << u+l << TheCall->getArg(i)->getSourceRange(); 322 323 // FIXME: VFP Intrinsics should error if VFP not present. 324 return false; 325} 326 327/// CheckFunctionCall - Check a direct function call for various correctness 328/// and safety properties not strictly enforced by the C type system. 329bool Sema::CheckFunctionCall(FunctionDecl *FDecl, CallExpr *TheCall) { 330 // Get the IdentifierInfo* for the called function. 331 IdentifierInfo *FnInfo = FDecl->getIdentifier(); 332 333 // None of the checks below are needed for functions that don't have 334 // simple names (e.g., C++ conversion functions). 335 if (!FnInfo) 336 return false; 337 338 // FIXME: This mechanism should be abstracted to be less fragile and 339 // more efficient. For example, just map function ids to custom 340 // handlers. 341 342 // Printf checking. 343 if (const FormatAttr *Format = FDecl->getAttr<FormatAttr>()) { 344 const bool b = Format->getType() == "scanf"; 345 if (b || CheckablePrintfAttr(Format, TheCall)) { 346 bool HasVAListArg = Format->getFirstArg() == 0; 347 CheckPrintfScanfArguments(TheCall, HasVAListArg, 348 Format->getFormatIdx() - 1, 349 HasVAListArg ? 0 : Format->getFirstArg() - 1, 350 !b); 351 } 352 } 353 354 specific_attr_iterator<NonNullAttr> 355 i = FDecl->specific_attr_begin<NonNullAttr>(), 356 e = FDecl->specific_attr_end<NonNullAttr>(); 357 358 for (; i != e; ++i) 359 CheckNonNullArguments(*i, TheCall); 360 361 return false; 362} 363 364bool Sema::CheckBlockCall(NamedDecl *NDecl, CallExpr *TheCall) { 365 // Printf checking. 366 const FormatAttr *Format = NDecl->getAttr<FormatAttr>(); 367 if (!Format) 368 return false; 369 370 const VarDecl *V = dyn_cast<VarDecl>(NDecl); 371 if (!V) 372 return false; 373 374 QualType Ty = V->getType(); 375 if (!Ty->isBlockPointerType()) 376 return false; 377 378 const bool b = Format->getType() == "scanf"; 379 if (!b && !CheckablePrintfAttr(Format, TheCall)) 380 return false; 381 382 bool HasVAListArg = Format->getFirstArg() == 0; 383 CheckPrintfScanfArguments(TheCall, HasVAListArg, Format->getFormatIdx() - 1, 384 HasVAListArg ? 0 : Format->getFirstArg() - 1, !b); 385 386 return false; 387} 388 389/// SemaBuiltinAtomicOverloaded - We have a call to a function like 390/// __sync_fetch_and_add, which is an overloaded function based on the pointer 391/// type of its first argument. The main ActOnCallExpr routines have already 392/// promoted the types of arguments because all of these calls are prototyped as 393/// void(...). 394/// 395/// This function goes through and does final semantic checking for these 396/// builtins, 397ExprResult 398Sema::SemaBuiltinAtomicOverloaded(ExprResult TheCallResult) { 399 CallExpr *TheCall = (CallExpr *)TheCallResult.get(); 400 DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts()); 401 FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl()); 402 403 // Ensure that we have at least one argument to do type inference from. 404 if (TheCall->getNumArgs() < 1) { 405 Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args_at_least) 406 << 0 << 1 << TheCall->getNumArgs() 407 << TheCall->getCallee()->getSourceRange(); 408 return ExprError(); 409 } 410 411 // Inspect the first argument of the atomic builtin. This should always be 412 // a pointer type, whose element is an integral scalar or pointer type. 413 // Because it is a pointer type, we don't have to worry about any implicit 414 // casts here. 415 // FIXME: We don't allow floating point scalars as input. 416 Expr *FirstArg = TheCall->getArg(0); 417 if (!FirstArg->getType()->isPointerType()) { 418 Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer) 419 << FirstArg->getType() << FirstArg->getSourceRange(); 420 return ExprError(); 421 } 422 423 QualType ValType = 424 FirstArg->getType()->getAs<PointerType>()->getPointeeType(); 425 if (!ValType->isIntegerType() && !ValType->isPointerType() && 426 !ValType->isBlockPointerType()) { 427 Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer_intptr) 428 << FirstArg->getType() << FirstArg->getSourceRange(); 429 return ExprError(); 430 } 431 432 // The majority of builtins return a value, but a few have special return 433 // types, so allow them to override appropriately below. 434 QualType ResultType = ValType; 435 436 // We need to figure out which concrete builtin this maps onto. For example, 437 // __sync_fetch_and_add with a 2 byte object turns into 438 // __sync_fetch_and_add_2. 439#define BUILTIN_ROW(x) \ 440 { Builtin::BI##x##_1, Builtin::BI##x##_2, Builtin::BI##x##_4, \ 441 Builtin::BI##x##_8, Builtin::BI##x##_16 } 442 443 static const unsigned BuiltinIndices[][5] = { 444 BUILTIN_ROW(__sync_fetch_and_add), 445 BUILTIN_ROW(__sync_fetch_and_sub), 446 BUILTIN_ROW(__sync_fetch_and_or), 447 BUILTIN_ROW(__sync_fetch_and_and), 448 BUILTIN_ROW(__sync_fetch_and_xor), 449 450 BUILTIN_ROW(__sync_add_and_fetch), 451 BUILTIN_ROW(__sync_sub_and_fetch), 452 BUILTIN_ROW(__sync_and_and_fetch), 453 BUILTIN_ROW(__sync_or_and_fetch), 454 BUILTIN_ROW(__sync_xor_and_fetch), 455 456 BUILTIN_ROW(__sync_val_compare_and_swap), 457 BUILTIN_ROW(__sync_bool_compare_and_swap), 458 BUILTIN_ROW(__sync_lock_test_and_set), 459 BUILTIN_ROW(__sync_lock_release) 460 }; 461#undef BUILTIN_ROW 462 463 // Determine the index of the size. 464 unsigned SizeIndex; 465 switch (Context.getTypeSizeInChars(ValType).getQuantity()) { 466 case 1: SizeIndex = 0; break; 467 case 2: SizeIndex = 1; break; 468 case 4: SizeIndex = 2; break; 469 case 8: SizeIndex = 3; break; 470 case 16: SizeIndex = 4; break; 471 default: 472 Diag(DRE->getLocStart(), diag::err_atomic_builtin_pointer_size) 473 << FirstArg->getType() << FirstArg->getSourceRange(); 474 return ExprError(); 475 } 476 477 // Each of these builtins has one pointer argument, followed by some number of 478 // values (0, 1 or 2) followed by a potentially empty varags list of stuff 479 // that we ignore. Find out which row of BuiltinIndices to read from as well 480 // as the number of fixed args. 481 unsigned BuiltinID = FDecl->getBuiltinID(); 482 unsigned BuiltinIndex, NumFixed = 1; 483 switch (BuiltinID) { 484 default: assert(0 && "Unknown overloaded atomic builtin!"); 485 case Builtin::BI__sync_fetch_and_add: BuiltinIndex = 0; break; 486 case Builtin::BI__sync_fetch_and_sub: BuiltinIndex = 1; break; 487 case Builtin::BI__sync_fetch_and_or: BuiltinIndex = 2; break; 488 case Builtin::BI__sync_fetch_and_and: BuiltinIndex = 3; break; 489 case Builtin::BI__sync_fetch_and_xor: BuiltinIndex = 4; break; 490 491 case Builtin::BI__sync_add_and_fetch: BuiltinIndex = 5; break; 492 case Builtin::BI__sync_sub_and_fetch: BuiltinIndex = 6; break; 493 case Builtin::BI__sync_and_and_fetch: BuiltinIndex = 7; break; 494 case Builtin::BI__sync_or_and_fetch: BuiltinIndex = 8; break; 495 case Builtin::BI__sync_xor_and_fetch: BuiltinIndex = 9; break; 496 497 case Builtin::BI__sync_val_compare_and_swap: 498 BuiltinIndex = 10; 499 NumFixed = 2; 500 break; 501 case Builtin::BI__sync_bool_compare_and_swap: 502 BuiltinIndex = 11; 503 NumFixed = 2; 504 ResultType = Context.BoolTy; 505 break; 506 case Builtin::BI__sync_lock_test_and_set: BuiltinIndex = 12; break; 507 case Builtin::BI__sync_lock_release: 508 BuiltinIndex = 13; 509 NumFixed = 0; 510 ResultType = Context.VoidTy; 511 break; 512 } 513 514 // Now that we know how many fixed arguments we expect, first check that we 515 // have at least that many. 516 if (TheCall->getNumArgs() < 1+NumFixed) { 517 Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args_at_least) 518 << 0 << 1+NumFixed << TheCall->getNumArgs() 519 << TheCall->getCallee()->getSourceRange(); 520 return ExprError(); 521 } 522 523 // Get the decl for the concrete builtin from this, we can tell what the 524 // concrete integer type we should convert to is. 525 unsigned NewBuiltinID = BuiltinIndices[BuiltinIndex][SizeIndex]; 526 const char *NewBuiltinName = Context.BuiltinInfo.GetName(NewBuiltinID); 527 IdentifierInfo *NewBuiltinII = PP.getIdentifierInfo(NewBuiltinName); 528 FunctionDecl *NewBuiltinDecl = 529 cast<FunctionDecl>(LazilyCreateBuiltin(NewBuiltinII, NewBuiltinID, 530 TUScope, false, DRE->getLocStart())); 531 532 // The first argument --- the pointer --- has a fixed type; we 533 // deduce the types of the rest of the arguments accordingly. Walk 534 // the remaining arguments, converting them to the deduced value type. 535 for (unsigned i = 0; i != NumFixed; ++i) { 536 Expr *Arg = TheCall->getArg(i+1); 537 538 // If the argument is an implicit cast, then there was a promotion due to 539 // "...", just remove it now. 540 if (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Arg)) { 541 Arg = ICE->getSubExpr(); 542 ICE->setSubExpr(0); 543 TheCall->setArg(i+1, Arg); 544 } 545 546 // GCC does an implicit conversion to the pointer or integer ValType. This 547 // can fail in some cases (1i -> int**), check for this error case now. 548 CastKind Kind = CK_Unknown; 549 CXXCastPath BasePath; 550 if (CheckCastTypes(Arg->getSourceRange(), ValType, Arg, Kind, BasePath)) 551 return ExprError(); 552 553 // Okay, we have something that *can* be converted to the right type. Check 554 // to see if there is a potentially weird extension going on here. This can 555 // happen when you do an atomic operation on something like an char* and 556 // pass in 42. The 42 gets converted to char. This is even more strange 557 // for things like 45.123 -> char, etc. 558 // FIXME: Do this check. 559 ImpCastExprToType(Arg, ValType, Kind, VK_RValue, &BasePath); 560 TheCall->setArg(i+1, Arg); 561 } 562 563 // Switch the DeclRefExpr to refer to the new decl. 564 DRE->setDecl(NewBuiltinDecl); 565 DRE->setType(NewBuiltinDecl->getType()); 566 567 // Set the callee in the CallExpr. 568 // FIXME: This leaks the original parens and implicit casts. 569 Expr *PromotedCall = DRE; 570 UsualUnaryConversions(PromotedCall); 571 TheCall->setCallee(PromotedCall); 572 573 // Change the result type of the call to match the original value type. This 574 // is arbitrary, but the codegen for these builtins ins design to handle it 575 // gracefully. 576 TheCall->setType(ResultType); 577 578 return move(TheCallResult); 579} 580 581 582/// CheckObjCString - Checks that the argument to the builtin 583/// CFString constructor is correct 584/// FIXME: GCC currently emits the following warning: 585/// "warning: input conversion stopped due to an input byte that does not 586/// belong to the input codeset UTF-8" 587/// Note: It might also make sense to do the UTF-16 conversion here (would 588/// simplify the backend). 589bool Sema::CheckObjCString(Expr *Arg) { 590 Arg = Arg->IgnoreParenCasts(); 591 StringLiteral *Literal = dyn_cast<StringLiteral>(Arg); 592 593 if (!Literal || Literal->isWide()) { 594 Diag(Arg->getLocStart(), diag::err_cfstring_literal_not_string_constant) 595 << Arg->getSourceRange(); 596 return true; 597 } 598 599 size_t NulPos = Literal->getString().find('\0'); 600 if (NulPos != llvm::StringRef::npos) { 601 Diag(getLocationOfStringLiteralByte(Literal, NulPos), 602 diag::warn_cfstring_literal_contains_nul_character) 603 << Arg->getSourceRange(); 604 } 605 606 return false; 607} 608 609/// SemaBuiltinVAStart - Check the arguments to __builtin_va_start for validity. 610/// Emit an error and return true on failure, return false on success. 611bool Sema::SemaBuiltinVAStart(CallExpr *TheCall) { 612 Expr *Fn = TheCall->getCallee(); 613 if (TheCall->getNumArgs() > 2) { 614 Diag(TheCall->getArg(2)->getLocStart(), 615 diag::err_typecheck_call_too_many_args) 616 << 0 /*function call*/ << 2 << TheCall->getNumArgs() 617 << Fn->getSourceRange() 618 << SourceRange(TheCall->getArg(2)->getLocStart(), 619 (*(TheCall->arg_end()-1))->getLocEnd()); 620 return true; 621 } 622 623 if (TheCall->getNumArgs() < 2) { 624 return Diag(TheCall->getLocEnd(), 625 diag::err_typecheck_call_too_few_args_at_least) 626 << 0 /*function call*/ << 2 << TheCall->getNumArgs(); 627 } 628 629 // Determine whether the current function is variadic or not. 630 BlockScopeInfo *CurBlock = getCurBlock(); 631 bool isVariadic; 632 if (CurBlock) 633 isVariadic = CurBlock->TheDecl->isVariadic(); 634 else if (FunctionDecl *FD = getCurFunctionDecl()) 635 isVariadic = FD->isVariadic(); 636 else 637 isVariadic = getCurMethodDecl()->isVariadic(); 638 639 if (!isVariadic) { 640 Diag(Fn->getLocStart(), diag::err_va_start_used_in_non_variadic_function); 641 return true; 642 } 643 644 // Verify that the second argument to the builtin is the last argument of the 645 // current function or method. 646 bool SecondArgIsLastNamedArgument = false; 647 const Expr *Arg = TheCall->getArg(1)->IgnoreParenCasts(); 648 649 if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Arg)) { 650 if (const ParmVarDecl *PV = dyn_cast<ParmVarDecl>(DR->getDecl())) { 651 // FIXME: This isn't correct for methods (results in bogus warning). 652 // Get the last formal in the current function. 653 const ParmVarDecl *LastArg; 654 if (CurBlock) 655 LastArg = *(CurBlock->TheDecl->param_end()-1); 656 else if (FunctionDecl *FD = getCurFunctionDecl()) 657 LastArg = *(FD->param_end()-1); 658 else 659 LastArg = *(getCurMethodDecl()->param_end()-1); 660 SecondArgIsLastNamedArgument = PV == LastArg; 661 } 662 } 663 664 if (!SecondArgIsLastNamedArgument) 665 Diag(TheCall->getArg(1)->getLocStart(), 666 diag::warn_second_parameter_of_va_start_not_last_named_argument); 667 return false; 668} 669 670/// SemaBuiltinUnorderedCompare - Handle functions like __builtin_isgreater and 671/// friends. This is declared to take (...), so we have to check everything. 672bool Sema::SemaBuiltinUnorderedCompare(CallExpr *TheCall) { 673 if (TheCall->getNumArgs() < 2) 674 return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args) 675 << 0 << 2 << TheCall->getNumArgs()/*function call*/; 676 if (TheCall->getNumArgs() > 2) 677 return Diag(TheCall->getArg(2)->getLocStart(), 678 diag::err_typecheck_call_too_many_args) 679 << 0 /*function call*/ << 2 << TheCall->getNumArgs() 680 << SourceRange(TheCall->getArg(2)->getLocStart(), 681 (*(TheCall->arg_end()-1))->getLocEnd()); 682 683 Expr *OrigArg0 = TheCall->getArg(0); 684 Expr *OrigArg1 = TheCall->getArg(1); 685 686 // Do standard promotions between the two arguments, returning their common 687 // type. 688 QualType Res = UsualArithmeticConversions(OrigArg0, OrigArg1, false); 689 690 // Make sure any conversions are pushed back into the call; this is 691 // type safe since unordered compare builtins are declared as "_Bool 692 // foo(...)". 693 TheCall->setArg(0, OrigArg0); 694 TheCall->setArg(1, OrigArg1); 695 696 if (OrigArg0->isTypeDependent() || OrigArg1->isTypeDependent()) 697 return false; 698 699 // If the common type isn't a real floating type, then the arguments were 700 // invalid for this operation. 701 if (!Res->isRealFloatingType()) 702 return Diag(OrigArg0->getLocStart(), 703 diag::err_typecheck_call_invalid_ordered_compare) 704 << OrigArg0->getType() << OrigArg1->getType() 705 << SourceRange(OrigArg0->getLocStart(), OrigArg1->getLocEnd()); 706 707 return false; 708} 709 710/// SemaBuiltinSemaBuiltinFPClassification - Handle functions like 711/// __builtin_isnan and friends. This is declared to take (...), so we have 712/// to check everything. We expect the last argument to be a floating point 713/// value. 714bool Sema::SemaBuiltinFPClassification(CallExpr *TheCall, unsigned NumArgs) { 715 if (TheCall->getNumArgs() < NumArgs) 716 return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args) 717 << 0 << NumArgs << TheCall->getNumArgs()/*function call*/; 718 if (TheCall->getNumArgs() > NumArgs) 719 return Diag(TheCall->getArg(NumArgs)->getLocStart(), 720 diag::err_typecheck_call_too_many_args) 721 << 0 /*function call*/ << NumArgs << TheCall->getNumArgs() 722 << SourceRange(TheCall->getArg(NumArgs)->getLocStart(), 723 (*(TheCall->arg_end()-1))->getLocEnd()); 724 725 Expr *OrigArg = TheCall->getArg(NumArgs-1); 726 727 if (OrigArg->isTypeDependent()) 728 return false; 729 730 // This operation requires a non-_Complex floating-point number. 731 if (!OrigArg->getType()->isRealFloatingType()) 732 return Diag(OrigArg->getLocStart(), 733 diag::err_typecheck_call_invalid_unary_fp) 734 << OrigArg->getType() << OrigArg->getSourceRange(); 735 736 // If this is an implicit conversion from float -> double, remove it. 737 if (ImplicitCastExpr *Cast = dyn_cast<ImplicitCastExpr>(OrigArg)) { 738 Expr *CastArg = Cast->getSubExpr(); 739 if (CastArg->getType()->isSpecificBuiltinType(BuiltinType::Float)) { 740 assert(Cast->getType()->isSpecificBuiltinType(BuiltinType::Double) && 741 "promotion from float to double is the only expected cast here"); 742 Cast->setSubExpr(0); 743 TheCall->setArg(NumArgs-1, CastArg); 744 OrigArg = CastArg; 745 } 746 } 747 748 return false; 749} 750 751/// SemaBuiltinShuffleVector - Handle __builtin_shufflevector. 752// This is declared to take (...), so we have to check everything. 753ExprResult Sema::SemaBuiltinShuffleVector(CallExpr *TheCall) { 754 if (TheCall->getNumArgs() < 2) 755 return ExprError(Diag(TheCall->getLocEnd(), 756 diag::err_typecheck_call_too_few_args_at_least) 757 << 0 /*function call*/ << 2 << TheCall->getNumArgs() 758 << TheCall->getSourceRange()); 759 760 // Determine which of the following types of shufflevector we're checking: 761 // 1) unary, vector mask: (lhs, mask) 762 // 2) binary, vector mask: (lhs, rhs, mask) 763 // 3) binary, scalar mask: (lhs, rhs, index, ..., index) 764 QualType resType = TheCall->getArg(0)->getType(); 765 unsigned numElements = 0; 766 767 if (!TheCall->getArg(0)->isTypeDependent() && 768 !TheCall->getArg(1)->isTypeDependent()) { 769 QualType LHSType = TheCall->getArg(0)->getType(); 770 QualType RHSType = TheCall->getArg(1)->getType(); 771 772 if (!LHSType->isVectorType() || !RHSType->isVectorType()) { 773 Diag(TheCall->getLocStart(), diag::err_shufflevector_non_vector) 774 << SourceRange(TheCall->getArg(0)->getLocStart(), 775 TheCall->getArg(1)->getLocEnd()); 776 return ExprError(); 777 } 778 779 numElements = LHSType->getAs<VectorType>()->getNumElements(); 780 unsigned numResElements = TheCall->getNumArgs() - 2; 781 782 // Check to see if we have a call with 2 vector arguments, the unary shuffle 783 // with mask. If so, verify that RHS is an integer vector type with the 784 // same number of elts as lhs. 785 if (TheCall->getNumArgs() == 2) { 786 if (!RHSType->hasIntegerRepresentation() || 787 RHSType->getAs<VectorType>()->getNumElements() != numElements) 788 Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector) 789 << SourceRange(TheCall->getArg(1)->getLocStart(), 790 TheCall->getArg(1)->getLocEnd()); 791 numResElements = numElements; 792 } 793 else if (!Context.hasSameUnqualifiedType(LHSType, RHSType)) { 794 Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector) 795 << SourceRange(TheCall->getArg(0)->getLocStart(), 796 TheCall->getArg(1)->getLocEnd()); 797 return ExprError(); 798 } else if (numElements != numResElements) { 799 QualType eltType = LHSType->getAs<VectorType>()->getElementType(); 800 resType = Context.getVectorType(eltType, numResElements, 801 VectorType::NotAltiVec); 802 } 803 } 804 805 for (unsigned i = 2; i < TheCall->getNumArgs(); i++) { 806 if (TheCall->getArg(i)->isTypeDependent() || 807 TheCall->getArg(i)->isValueDependent()) 808 continue; 809 810 llvm::APSInt Result(32); 811 if (!TheCall->getArg(i)->isIntegerConstantExpr(Result, Context)) 812 return ExprError(Diag(TheCall->getLocStart(), 813 diag::err_shufflevector_nonconstant_argument) 814 << TheCall->getArg(i)->getSourceRange()); 815 816 if (Result.getActiveBits() > 64 || Result.getZExtValue() >= numElements*2) 817 return ExprError(Diag(TheCall->getLocStart(), 818 diag::err_shufflevector_argument_too_large) 819 << TheCall->getArg(i)->getSourceRange()); 820 } 821 822 llvm::SmallVector<Expr*, 32> exprs; 823 824 for (unsigned i = 0, e = TheCall->getNumArgs(); i != e; i++) { 825 exprs.push_back(TheCall->getArg(i)); 826 TheCall->setArg(i, 0); 827 } 828 829 return Owned(new (Context) ShuffleVectorExpr(Context, exprs.begin(), 830 exprs.size(), resType, 831 TheCall->getCallee()->getLocStart(), 832 TheCall->getRParenLoc())); 833} 834 835/// SemaBuiltinPrefetch - Handle __builtin_prefetch. 836// This is declared to take (const void*, ...) and can take two 837// optional constant int args. 838bool Sema::SemaBuiltinPrefetch(CallExpr *TheCall) { 839 unsigned NumArgs = TheCall->getNumArgs(); 840 841 if (NumArgs > 3) 842 return Diag(TheCall->getLocEnd(), 843 diag::err_typecheck_call_too_many_args_at_most) 844 << 0 /*function call*/ << 3 << NumArgs 845 << TheCall->getSourceRange(); 846 847 // Argument 0 is checked for us and the remaining arguments must be 848 // constant integers. 849 for (unsigned i = 1; i != NumArgs; ++i) { 850 Expr *Arg = TheCall->getArg(i); 851 852 llvm::APSInt Result; 853 if (SemaBuiltinConstantArg(TheCall, i, Result)) 854 return true; 855 856 // FIXME: gcc issues a warning and rewrites these to 0. These 857 // seems especially odd for the third argument since the default 858 // is 3. 859 if (i == 1) { 860 if (Result.getLimitedValue() > 1) 861 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 862 << "0" << "1" << Arg->getSourceRange(); 863 } else { 864 if (Result.getLimitedValue() > 3) 865 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 866 << "0" << "3" << Arg->getSourceRange(); 867 } 868 } 869 870 return false; 871} 872 873/// SemaBuiltinConstantArg - Handle a check if argument ArgNum of CallExpr 874/// TheCall is a constant expression. 875bool Sema::SemaBuiltinConstantArg(CallExpr *TheCall, int ArgNum, 876 llvm::APSInt &Result) { 877 Expr *Arg = TheCall->getArg(ArgNum); 878 DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts()); 879 FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl()); 880 881 if (Arg->isTypeDependent() || Arg->isValueDependent()) return false; 882 883 if (!Arg->isIntegerConstantExpr(Result, Context)) 884 return Diag(TheCall->getLocStart(), diag::err_constant_integer_arg_type) 885 << FDecl->getDeclName() << Arg->getSourceRange(); 886 887 return false; 888} 889 890/// SemaBuiltinObjectSize - Handle __builtin_object_size(void *ptr, 891/// int type). This simply type checks that type is one of the defined 892/// constants (0-3). 893// For compatability check 0-3, llvm only handles 0 and 2. 894bool Sema::SemaBuiltinObjectSize(CallExpr *TheCall) { 895 llvm::APSInt Result; 896 897 // Check constant-ness first. 898 if (SemaBuiltinConstantArg(TheCall, 1, Result)) 899 return true; 900 901 Expr *Arg = TheCall->getArg(1); 902 if (Result.getSExtValue() < 0 || Result.getSExtValue() > 3) { 903 return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) 904 << "0" << "3" << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); 905 } 906 907 return false; 908} 909 910/// SemaBuiltinLongjmp - Handle __builtin_longjmp(void *env[5], int val). 911/// This checks that val is a constant 1. 912bool Sema::SemaBuiltinLongjmp(CallExpr *TheCall) { 913 Expr *Arg = TheCall->getArg(1); 914 llvm::APSInt Result; 915 916 // TODO: This is less than ideal. Overload this to take a value. 917 if (SemaBuiltinConstantArg(TheCall, 1, Result)) 918 return true; 919 920 if (Result != 1) 921 return Diag(TheCall->getLocStart(), diag::err_builtin_longjmp_invalid_val) 922 << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); 923 924 return false; 925} 926 927// Handle i > 1 ? "x" : "y", recursivelly 928bool Sema::SemaCheckStringLiteral(const Expr *E, const CallExpr *TheCall, 929 bool HasVAListArg, 930 unsigned format_idx, unsigned firstDataArg, 931 bool isPrintf) { 932 933 if (E->isTypeDependent() || E->isValueDependent()) 934 return false; 935 936 switch (E->getStmtClass()) { 937 case Stmt::ConditionalOperatorClass: { 938 const ConditionalOperator *C = cast<ConditionalOperator>(E); 939 return SemaCheckStringLiteral(C->getTrueExpr(), TheCall, HasVAListArg, 940 format_idx, firstDataArg, isPrintf) 941 && SemaCheckStringLiteral(C->getRHS(), TheCall, HasVAListArg, 942 format_idx, firstDataArg, isPrintf); 943 } 944 945 case Stmt::ImplicitCastExprClass: { 946 const ImplicitCastExpr *Expr = cast<ImplicitCastExpr>(E); 947 return SemaCheckStringLiteral(Expr->getSubExpr(), TheCall, HasVAListArg, 948 format_idx, firstDataArg, isPrintf); 949 } 950 951 case Stmt::ParenExprClass: { 952 const ParenExpr *Expr = cast<ParenExpr>(E); 953 return SemaCheckStringLiteral(Expr->getSubExpr(), TheCall, HasVAListArg, 954 format_idx, firstDataArg, isPrintf); 955 } 956 957 case Stmt::DeclRefExprClass: { 958 const DeclRefExpr *DR = cast<DeclRefExpr>(E); 959 960 // As an exception, do not flag errors for variables binding to 961 // const string literals. 962 if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) { 963 bool isConstant = false; 964 QualType T = DR->getType(); 965 966 if (const ArrayType *AT = Context.getAsArrayType(T)) { 967 isConstant = AT->getElementType().isConstant(Context); 968 } else if (const PointerType *PT = T->getAs<PointerType>()) { 969 isConstant = T.isConstant(Context) && 970 PT->getPointeeType().isConstant(Context); 971 } 972 973 if (isConstant) { 974 if (const Expr *Init = VD->getAnyInitializer()) 975 return SemaCheckStringLiteral(Init, TheCall, 976 HasVAListArg, format_idx, firstDataArg, 977 isPrintf); 978 } 979 980 // For vprintf* functions (i.e., HasVAListArg==true), we add a 981 // special check to see if the format string is a function parameter 982 // of the function calling the printf function. If the function 983 // has an attribute indicating it is a printf-like function, then we 984 // should suppress warnings concerning non-literals being used in a call 985 // to a vprintf function. For example: 986 // 987 // void 988 // logmessage(char const *fmt __attribute__ (format (printf, 1, 2)), ...){ 989 // va_list ap; 990 // va_start(ap, fmt); 991 // vprintf(fmt, ap); // Do NOT emit a warning about "fmt". 992 // ... 993 // 994 // 995 // FIXME: We don't have full attribute support yet, so just check to see 996 // if the argument is a DeclRefExpr that references a parameter. We'll 997 // add proper support for checking the attribute later. 998 if (HasVAListArg) 999 if (isa<ParmVarDecl>(VD)) 1000 return true; 1001 } 1002 1003 return false; 1004 } 1005 1006 case Stmt::CallExprClass: { 1007 const CallExpr *CE = cast<CallExpr>(E); 1008 if (const ImplicitCastExpr *ICE 1009 = dyn_cast<ImplicitCastExpr>(CE->getCallee())) { 1010 if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(ICE->getSubExpr())) { 1011 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(DRE->getDecl())) { 1012 if (const FormatArgAttr *FA = FD->getAttr<FormatArgAttr>()) { 1013 unsigned ArgIndex = FA->getFormatIdx(); 1014 const Expr *Arg = CE->getArg(ArgIndex - 1); 1015 1016 return SemaCheckStringLiteral(Arg, TheCall, HasVAListArg, 1017 format_idx, firstDataArg, isPrintf); 1018 } 1019 } 1020 } 1021 } 1022 1023 return false; 1024 } 1025 case Stmt::ObjCStringLiteralClass: 1026 case Stmt::StringLiteralClass: { 1027 const StringLiteral *StrE = NULL; 1028 1029 if (const ObjCStringLiteral *ObjCFExpr = dyn_cast<ObjCStringLiteral>(E)) 1030 StrE = ObjCFExpr->getString(); 1031 else 1032 StrE = cast<StringLiteral>(E); 1033 1034 if (StrE) { 1035 CheckFormatString(StrE, E, TheCall, HasVAListArg, format_idx, 1036 firstDataArg, isPrintf); 1037 return true; 1038 } 1039 1040 return false; 1041 } 1042 1043 default: 1044 return false; 1045 } 1046} 1047 1048void 1049Sema::CheckNonNullArguments(const NonNullAttr *NonNull, 1050 const CallExpr *TheCall) { 1051 for (NonNullAttr::args_iterator i = NonNull->args_begin(), 1052 e = NonNull->args_end(); 1053 i != e; ++i) { 1054 const Expr *ArgExpr = TheCall->getArg(*i); 1055 if (ArgExpr->isNullPointerConstant(Context, 1056 Expr::NPC_ValueDependentIsNotNull)) 1057 Diag(TheCall->getCallee()->getLocStart(), diag::warn_null_arg) 1058 << ArgExpr->getSourceRange(); 1059 } 1060} 1061 1062/// CheckPrintfScanfArguments - Check calls to printf and scanf (and similar 1063/// functions) for correct use of format strings. 1064void 1065Sema::CheckPrintfScanfArguments(const CallExpr *TheCall, bool HasVAListArg, 1066 unsigned format_idx, unsigned firstDataArg, 1067 bool isPrintf) { 1068 1069 const Expr *Fn = TheCall->getCallee(); 1070 1071 // The way the format attribute works in GCC, the implicit this argument 1072 // of member functions is counted. However, it doesn't appear in our own 1073 // lists, so decrement format_idx in that case. 1074 if (isa<CXXMemberCallExpr>(TheCall)) { 1075 // Catch a format attribute mistakenly referring to the object argument. 1076 if (format_idx == 0) 1077 return; 1078 --format_idx; 1079 if(firstDataArg != 0) 1080 --firstDataArg; 1081 } 1082 1083 // CHECK: printf/scanf-like function is called with no format string. 1084 if (format_idx >= TheCall->getNumArgs()) { 1085 Diag(TheCall->getRParenLoc(), diag::warn_missing_format_string) 1086 << Fn->getSourceRange(); 1087 return; 1088 } 1089 1090 const Expr *OrigFormatExpr = TheCall->getArg(format_idx)->IgnoreParenCasts(); 1091 1092 // CHECK: format string is not a string literal. 1093 // 1094 // Dynamically generated format strings are difficult to 1095 // automatically vet at compile time. Requiring that format strings 1096 // are string literals: (1) permits the checking of format strings by 1097 // the compiler and thereby (2) can practically remove the source of 1098 // many format string exploits. 1099 1100 // Format string can be either ObjC string (e.g. @"%d") or 1101 // C string (e.g. "%d") 1102 // ObjC string uses the same format specifiers as C string, so we can use 1103 // the same format string checking logic for both ObjC and C strings. 1104 if (SemaCheckStringLiteral(OrigFormatExpr, TheCall, HasVAListArg, format_idx, 1105 firstDataArg, isPrintf)) 1106 return; // Literal format string found, check done! 1107 1108 // If there are no arguments specified, warn with -Wformat-security, otherwise 1109 // warn only with -Wformat-nonliteral. 1110 if (TheCall->getNumArgs() == format_idx+1) 1111 Diag(TheCall->getArg(format_idx)->getLocStart(), 1112 diag::warn_format_nonliteral_noargs) 1113 << OrigFormatExpr->getSourceRange(); 1114 else 1115 Diag(TheCall->getArg(format_idx)->getLocStart(), 1116 diag::warn_format_nonliteral) 1117 << OrigFormatExpr->getSourceRange(); 1118} 1119 1120namespace { 1121class CheckFormatHandler : public analyze_format_string::FormatStringHandler { 1122protected: 1123 Sema &S; 1124 const StringLiteral *FExpr; 1125 const Expr *OrigFormatExpr; 1126 const unsigned FirstDataArg; 1127 const unsigned NumDataArgs; 1128 const bool IsObjCLiteral; 1129 const char *Beg; // Start of format string. 1130 const bool HasVAListArg; 1131 const CallExpr *TheCall; 1132 unsigned FormatIdx; 1133 llvm::BitVector CoveredArgs; 1134 bool usesPositionalArgs; 1135 bool atFirstArg; 1136public: 1137 CheckFormatHandler(Sema &s, const StringLiteral *fexpr, 1138 const Expr *origFormatExpr, unsigned firstDataArg, 1139 unsigned numDataArgs, bool isObjCLiteral, 1140 const char *beg, bool hasVAListArg, 1141 const CallExpr *theCall, unsigned formatIdx) 1142 : S(s), FExpr(fexpr), OrigFormatExpr(origFormatExpr), 1143 FirstDataArg(firstDataArg), 1144 NumDataArgs(numDataArgs), 1145 IsObjCLiteral(isObjCLiteral), Beg(beg), 1146 HasVAListArg(hasVAListArg), 1147 TheCall(theCall), FormatIdx(formatIdx), 1148 usesPositionalArgs(false), atFirstArg(true) { 1149 CoveredArgs.resize(numDataArgs); 1150 CoveredArgs.reset(); 1151 } 1152 1153 void DoneProcessing(); 1154 1155 void HandleIncompleteSpecifier(const char *startSpecifier, 1156 unsigned specifierLen); 1157 1158 virtual void HandleInvalidPosition(const char *startSpecifier, 1159 unsigned specifierLen, 1160 analyze_format_string::PositionContext p); 1161 1162 virtual void HandleZeroPosition(const char *startPos, unsigned posLen); 1163 1164 void HandleNullChar(const char *nullCharacter); 1165 1166protected: 1167 bool HandleInvalidConversionSpecifier(unsigned argIndex, SourceLocation Loc, 1168 const char *startSpec, 1169 unsigned specifierLen, 1170 const char *csStart, unsigned csLen); 1171 1172 SourceRange getFormatStringRange(); 1173 CharSourceRange getSpecifierRange(const char *startSpecifier, 1174 unsigned specifierLen); 1175 SourceLocation getLocationOfByte(const char *x); 1176 1177 const Expr *getDataArg(unsigned i) const; 1178 1179 bool CheckNumArgs(const analyze_format_string::FormatSpecifier &FS, 1180 const analyze_format_string::ConversionSpecifier &CS, 1181 const char *startSpecifier, unsigned specifierLen, 1182 unsigned argIndex); 1183}; 1184} 1185 1186SourceRange CheckFormatHandler::getFormatStringRange() { 1187 return OrigFormatExpr->getSourceRange(); 1188} 1189 1190CharSourceRange CheckFormatHandler:: 1191getSpecifierRange(const char *startSpecifier, unsigned specifierLen) { 1192 SourceLocation Start = getLocationOfByte(startSpecifier); 1193 SourceLocation End = getLocationOfByte(startSpecifier + specifierLen - 1); 1194 1195 // Advance the end SourceLocation by one due to half-open ranges. 1196 End = End.getFileLocWithOffset(1); 1197 1198 return CharSourceRange::getCharRange(Start, End); 1199} 1200 1201SourceLocation CheckFormatHandler::getLocationOfByte(const char *x) { 1202 return S.getLocationOfStringLiteralByte(FExpr, x - Beg); 1203} 1204 1205void CheckFormatHandler::HandleIncompleteSpecifier(const char *startSpecifier, 1206 unsigned specifierLen){ 1207 SourceLocation Loc = getLocationOfByte(startSpecifier); 1208 S.Diag(Loc, diag::warn_printf_incomplete_specifier) 1209 << getSpecifierRange(startSpecifier, specifierLen); 1210} 1211 1212void 1213CheckFormatHandler::HandleInvalidPosition(const char *startPos, unsigned posLen, 1214 analyze_format_string::PositionContext p) { 1215 SourceLocation Loc = getLocationOfByte(startPos); 1216 S.Diag(Loc, diag::warn_format_invalid_positional_specifier) 1217 << (unsigned) p << getSpecifierRange(startPos, posLen); 1218} 1219 1220void CheckFormatHandler::HandleZeroPosition(const char *startPos, 1221 unsigned posLen) { 1222 SourceLocation Loc = getLocationOfByte(startPos); 1223 S.Diag(Loc, diag::warn_format_zero_positional_specifier) 1224 << getSpecifierRange(startPos, posLen); 1225} 1226 1227void CheckFormatHandler::HandleNullChar(const char *nullCharacter) { 1228 // The presence of a null character is likely an error. 1229 S.Diag(getLocationOfByte(nullCharacter), 1230 diag::warn_printf_format_string_contains_null_char) 1231 << getFormatStringRange(); 1232} 1233 1234const Expr *CheckFormatHandler::getDataArg(unsigned i) const { 1235 return TheCall->getArg(FirstDataArg + i); 1236} 1237 1238void CheckFormatHandler::DoneProcessing() { 1239 // Does the number of data arguments exceed the number of 1240 // format conversions in the format string? 1241 if (!HasVAListArg) { 1242 // Find any arguments that weren't covered. 1243 CoveredArgs.flip(); 1244 signed notCoveredArg = CoveredArgs.find_first(); 1245 if (notCoveredArg >= 0) { 1246 assert((unsigned)notCoveredArg < NumDataArgs); 1247 S.Diag(getDataArg((unsigned) notCoveredArg)->getLocStart(), 1248 diag::warn_printf_data_arg_not_used) 1249 << getFormatStringRange(); 1250 } 1251 } 1252} 1253 1254bool 1255CheckFormatHandler::HandleInvalidConversionSpecifier(unsigned argIndex, 1256 SourceLocation Loc, 1257 const char *startSpec, 1258 unsigned specifierLen, 1259 const char *csStart, 1260 unsigned csLen) { 1261 1262 bool keepGoing = true; 1263 if (argIndex < NumDataArgs) { 1264 // Consider the argument coverered, even though the specifier doesn't 1265 // make sense. 1266 CoveredArgs.set(argIndex); 1267 } 1268 else { 1269 // If argIndex exceeds the number of data arguments we 1270 // don't issue a warning because that is just a cascade of warnings (and 1271 // they may have intended '%%' anyway). We don't want to continue processing 1272 // the format string after this point, however, as we will like just get 1273 // gibberish when trying to match arguments. 1274 keepGoing = false; 1275 } 1276 1277 S.Diag(Loc, diag::warn_format_invalid_conversion) 1278 << llvm::StringRef(csStart, csLen) 1279 << getSpecifierRange(startSpec, specifierLen); 1280 1281 return keepGoing; 1282} 1283 1284bool 1285CheckFormatHandler::CheckNumArgs( 1286 const analyze_format_string::FormatSpecifier &FS, 1287 const analyze_format_string::ConversionSpecifier &CS, 1288 const char *startSpecifier, unsigned specifierLen, unsigned argIndex) { 1289 1290 if (argIndex >= NumDataArgs) { 1291 if (FS.usesPositionalArg()) { 1292 S.Diag(getLocationOfByte(CS.getStart()), 1293 diag::warn_printf_positional_arg_exceeds_data_args) 1294 << (argIndex+1) << NumDataArgs 1295 << getSpecifierRange(startSpecifier, specifierLen); 1296 } 1297 else { 1298 S.Diag(getLocationOfByte(CS.getStart()), 1299 diag::warn_printf_insufficient_data_args) 1300 << getSpecifierRange(startSpecifier, specifierLen); 1301 } 1302 1303 return false; 1304 } 1305 return true; 1306} 1307 1308//===--- CHECK: Printf format string checking ------------------------------===// 1309 1310namespace { 1311class CheckPrintfHandler : public CheckFormatHandler { 1312public: 1313 CheckPrintfHandler(Sema &s, const StringLiteral *fexpr, 1314 const Expr *origFormatExpr, unsigned firstDataArg, 1315 unsigned numDataArgs, bool isObjCLiteral, 1316 const char *beg, bool hasVAListArg, 1317 const CallExpr *theCall, unsigned formatIdx) 1318 : CheckFormatHandler(s, fexpr, origFormatExpr, firstDataArg, 1319 numDataArgs, isObjCLiteral, beg, hasVAListArg, 1320 theCall, formatIdx) {} 1321 1322 1323 bool HandleInvalidPrintfConversionSpecifier( 1324 const analyze_printf::PrintfSpecifier &FS, 1325 const char *startSpecifier, 1326 unsigned specifierLen); 1327 1328 bool HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier &FS, 1329 const char *startSpecifier, 1330 unsigned specifierLen); 1331 1332 bool HandleAmount(const analyze_format_string::OptionalAmount &Amt, unsigned k, 1333 const char *startSpecifier, unsigned specifierLen); 1334 void HandleInvalidAmount(const analyze_printf::PrintfSpecifier &FS, 1335 const analyze_printf::OptionalAmount &Amt, 1336 unsigned type, 1337 const char *startSpecifier, unsigned specifierLen); 1338 void HandleFlag(const analyze_printf::PrintfSpecifier &FS, 1339 const analyze_printf::OptionalFlag &flag, 1340 const char *startSpecifier, unsigned specifierLen); 1341 void HandleIgnoredFlag(const analyze_printf::PrintfSpecifier &FS, 1342 const analyze_printf::OptionalFlag &ignoredFlag, 1343 const analyze_printf::OptionalFlag &flag, 1344 const char *startSpecifier, unsigned specifierLen); 1345}; 1346} 1347 1348bool CheckPrintfHandler::HandleInvalidPrintfConversionSpecifier( 1349 const analyze_printf::PrintfSpecifier &FS, 1350 const char *startSpecifier, 1351 unsigned specifierLen) { 1352 const analyze_printf::PrintfConversionSpecifier &CS = 1353 FS.getConversionSpecifier(); 1354 1355 return HandleInvalidConversionSpecifier(FS.getArgIndex(), 1356 getLocationOfByte(CS.getStart()), 1357 startSpecifier, specifierLen, 1358 CS.getStart(), CS.getLength()); 1359} 1360 1361bool CheckPrintfHandler::HandleAmount( 1362 const analyze_format_string::OptionalAmount &Amt, 1363 unsigned k, const char *startSpecifier, 1364 unsigned specifierLen) { 1365 1366 if (Amt.hasDataArgument()) { 1367 if (!HasVAListArg) { 1368 unsigned argIndex = Amt.getArgIndex(); 1369 if (argIndex >= NumDataArgs) { 1370 S.Diag(getLocationOfByte(Amt.getStart()), 1371 diag::warn_printf_asterisk_missing_arg) 1372 << k << getSpecifierRange(startSpecifier, specifierLen); 1373 // Don't do any more checking. We will just emit 1374 // spurious errors. 1375 return false; 1376 } 1377 1378 // Type check the data argument. It should be an 'int'. 1379 // Although not in conformance with C99, we also allow the argument to be 1380 // an 'unsigned int' as that is a reasonably safe case. GCC also 1381 // doesn't emit a warning for that case. 1382 CoveredArgs.set(argIndex); 1383 const Expr *Arg = getDataArg(argIndex); 1384 QualType T = Arg->getType(); 1385 1386 const analyze_printf::ArgTypeResult &ATR = Amt.getArgType(S.Context); 1387 assert(ATR.isValid()); 1388 1389 if (!ATR.matchesType(S.Context, T)) { 1390 S.Diag(getLocationOfByte(Amt.getStart()), 1391 diag::warn_printf_asterisk_wrong_type) 1392 << k 1393 << ATR.getRepresentativeType(S.Context) << T 1394 << getSpecifierRange(startSpecifier, specifierLen) 1395 << Arg->getSourceRange(); 1396 // Don't do any more checking. We will just emit 1397 // spurious errors. 1398 return false; 1399 } 1400 } 1401 } 1402 return true; 1403} 1404 1405void CheckPrintfHandler::HandleInvalidAmount( 1406 const analyze_printf::PrintfSpecifier &FS, 1407 const analyze_printf::OptionalAmount &Amt, 1408 unsigned type, 1409 const char *startSpecifier, 1410 unsigned specifierLen) { 1411 const analyze_printf::PrintfConversionSpecifier &CS = 1412 FS.getConversionSpecifier(); 1413 switch (Amt.getHowSpecified()) { 1414 case analyze_printf::OptionalAmount::Constant: 1415 S.Diag(getLocationOfByte(Amt.getStart()), 1416 diag::warn_printf_nonsensical_optional_amount) 1417 << type 1418 << CS.toString() 1419 << getSpecifierRange(startSpecifier, specifierLen) 1420 << FixItHint::CreateRemoval(getSpecifierRange(Amt.getStart(), 1421 Amt.getConstantLength())); 1422 break; 1423 1424 default: 1425 S.Diag(getLocationOfByte(Amt.getStart()), 1426 diag::warn_printf_nonsensical_optional_amount) 1427 << type 1428 << CS.toString() 1429 << getSpecifierRange(startSpecifier, specifierLen); 1430 break; 1431 } 1432} 1433 1434void CheckPrintfHandler::HandleFlag(const analyze_printf::PrintfSpecifier &FS, 1435 const analyze_printf::OptionalFlag &flag, 1436 const char *startSpecifier, 1437 unsigned specifierLen) { 1438 // Warn about pointless flag with a fixit removal. 1439 const analyze_printf::PrintfConversionSpecifier &CS = 1440 FS.getConversionSpecifier(); 1441 S.Diag(getLocationOfByte(flag.getPosition()), 1442 diag::warn_printf_nonsensical_flag) 1443 << flag.toString() << CS.toString() 1444 << getSpecifierRange(startSpecifier, specifierLen) 1445 << FixItHint::CreateRemoval(getSpecifierRange(flag.getPosition(), 1)); 1446} 1447 1448void CheckPrintfHandler::HandleIgnoredFlag( 1449 const analyze_printf::PrintfSpecifier &FS, 1450 const analyze_printf::OptionalFlag &ignoredFlag, 1451 const analyze_printf::OptionalFlag &flag, 1452 const char *startSpecifier, 1453 unsigned specifierLen) { 1454 // Warn about ignored flag with a fixit removal. 1455 S.Diag(getLocationOfByte(ignoredFlag.getPosition()), 1456 diag::warn_printf_ignored_flag) 1457 << ignoredFlag.toString() << flag.toString() 1458 << getSpecifierRange(startSpecifier, specifierLen) 1459 << FixItHint::CreateRemoval(getSpecifierRange( 1460 ignoredFlag.getPosition(), 1)); 1461} 1462 1463bool 1464CheckPrintfHandler::HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier 1465 &FS, 1466 const char *startSpecifier, 1467 unsigned specifierLen) { 1468 1469 using namespace analyze_format_string; 1470 using namespace analyze_printf; 1471 const PrintfConversionSpecifier &CS = FS.getConversionSpecifier(); 1472 1473 if (FS.consumesDataArgument()) { 1474 if (atFirstArg) { 1475 atFirstArg = false; 1476 usesPositionalArgs = FS.usesPositionalArg(); 1477 } 1478 else if (usesPositionalArgs != FS.usesPositionalArg()) { 1479 // Cannot mix-and-match positional and non-positional arguments. 1480 S.Diag(getLocationOfByte(CS.getStart()), 1481 diag::warn_format_mix_positional_nonpositional_args) 1482 << getSpecifierRange(startSpecifier, specifierLen); 1483 return false; 1484 } 1485 } 1486 1487 // First check if the field width, precision, and conversion specifier 1488 // have matching data arguments. 1489 if (!HandleAmount(FS.getFieldWidth(), /* field width */ 0, 1490 startSpecifier, specifierLen)) { 1491 return false; 1492 } 1493 1494 if (!HandleAmount(FS.getPrecision(), /* precision */ 1, 1495 startSpecifier, specifierLen)) { 1496 return false; 1497 } 1498 1499 if (!CS.consumesDataArgument()) { 1500 // FIXME: Technically specifying a precision or field width here 1501 // makes no sense. Worth issuing a warning at some point. 1502 return true; 1503 } 1504 1505 // Consume the argument. 1506 unsigned argIndex = FS.getArgIndex(); 1507 if (argIndex < NumDataArgs) { 1508 // The check to see if the argIndex is valid will come later. 1509 // We set the bit here because we may exit early from this 1510 // function if we encounter some other error. 1511 CoveredArgs.set(argIndex); 1512 } 1513 1514 // FreeBSD extensions 1515 if (CS.getKind() == ConversionSpecifier::bArg || CS.getKind() == ConversionSpecifier::DArg) { 1516 // claim the second argument 1517 CoveredArgs.set(argIndex + 1); 1518 1519 // Now type check the data expression that matches the 1520 // format specifier. 1521 const Expr *Ex = getDataArg(argIndex); 1522 const analyze_printf::ArgTypeResult &ATR = 1523 (CS.getKind() == ConversionSpecifier::bArg) ? 1524 ArgTypeResult(S.Context.IntTy) : ArgTypeResult::CStrTy; 1525 if (ATR.isValid() && !ATR.matchesType(S.Context, Ex->getType())) 1526 S.Diag(getLocationOfByte(CS.getStart()), 1527 diag::warn_printf_conversion_argument_type_mismatch) 1528 << ATR.getRepresentativeType(S.Context) << Ex->getType() 1529 << getSpecifierRange(startSpecifier, specifierLen) 1530 << Ex->getSourceRange(); 1531 1532 // Now type check the data expression that matches the 1533 // format specifier. 1534 Ex = getDataArg(argIndex + 1); 1535 const analyze_printf::ArgTypeResult &ATR2 = ArgTypeResult::CStrTy; 1536 if (ATR2.isValid() && !ATR2.matchesType(S.Context, Ex->getType())) 1537 S.Diag(getLocationOfByte(CS.getStart()), 1538 diag::warn_printf_conversion_argument_type_mismatch) 1539 << ATR2.getRepresentativeType(S.Context) << Ex->getType() 1540 << getSpecifierRange(startSpecifier, specifierLen) 1541 << Ex->getSourceRange(); 1542 1543 return true; 1544 } 1545 // END OF FREEBSD EXTENSIONS 1546 1547 // Check for using an Objective-C specific conversion specifier 1548 // in a non-ObjC literal. 1549 if (!IsObjCLiteral && CS.isObjCArg()) { 1550 return HandleInvalidPrintfConversionSpecifier(FS, startSpecifier, 1551 specifierLen); 1552 } 1553 1554 // Check for invalid use of field width 1555 if (!FS.hasValidFieldWidth()) { 1556 HandleInvalidAmount(FS, FS.getFieldWidth(), /* field width */ 0, 1557 startSpecifier, specifierLen); 1558 } 1559 1560 // Check for invalid use of precision 1561 if (!FS.hasValidPrecision()) { 1562 HandleInvalidAmount(FS, FS.getPrecision(), /* precision */ 1, 1563 startSpecifier, specifierLen); 1564 } 1565 1566 // Check each flag does not conflict with any other component. 1567 if (!FS.hasValidLeadingZeros()) 1568 HandleFlag(FS, FS.hasLeadingZeros(), startSpecifier, specifierLen); 1569 if (!FS.hasValidPlusPrefix()) 1570 HandleFlag(FS, FS.hasPlusPrefix(), startSpecifier, specifierLen); 1571 if (!FS.hasValidSpacePrefix()) 1572 HandleFlag(FS, FS.hasSpacePrefix(), startSpecifier, specifierLen); 1573 if (!FS.hasValidAlternativeForm()) 1574 HandleFlag(FS, FS.hasAlternativeForm(), startSpecifier, specifierLen); 1575 if (!FS.hasValidLeftJustified()) 1576 HandleFlag(FS, FS.isLeftJustified(), startSpecifier, specifierLen); 1577 1578 // Check that flags are not ignored by another flag 1579 if (FS.hasSpacePrefix() && FS.hasPlusPrefix()) // ' ' ignored by '+' 1580 HandleIgnoredFlag(FS, FS.hasSpacePrefix(), FS.hasPlusPrefix(), 1581 startSpecifier, specifierLen); 1582 if (FS.hasLeadingZeros() && FS.isLeftJustified()) // '0' ignored by '-' 1583 HandleIgnoredFlag(FS, FS.hasLeadingZeros(), FS.isLeftJustified(), 1584 startSpecifier, specifierLen); 1585 1586 // Check the length modifier is valid with the given conversion specifier. 1587 const LengthModifier &LM = FS.getLengthModifier(); 1588 if (!FS.hasValidLengthModifier()) 1589 S.Diag(getLocationOfByte(LM.getStart()), 1590 diag::warn_format_nonsensical_length) 1591 << LM.toString() << CS.toString() 1592 << getSpecifierRange(startSpecifier, specifierLen) 1593 << FixItHint::CreateRemoval(getSpecifierRange(LM.getStart(), 1594 LM.getLength())); 1595 1596 // Are we using '%n'? 1597 if (CS.getKind() == ConversionSpecifier::nArg) { 1598 // Issue a warning about this being a possible security issue. 1599 S.Diag(getLocationOfByte(CS.getStart()), diag::warn_printf_write_back) 1600 << getSpecifierRange(startSpecifier, specifierLen); 1601 // Continue checking the other format specifiers. 1602 return true; 1603 } 1604 1605 // The remaining checks depend on the data arguments. 1606 if (HasVAListArg) 1607 return true; 1608 1609 if (!CheckNumArgs(FS, CS, startSpecifier, specifierLen, argIndex)) 1610 return false; 1611 1612 // Now type check the data expression that matches the 1613 // format specifier. 1614 const Expr *Ex = getDataArg(argIndex); 1615 const analyze_printf::ArgTypeResult &ATR = FS.getArgType(S.Context); 1616 if (ATR.isValid() && !ATR.matchesType(S.Context, Ex->getType())) { 1617 // Check if we didn't match because of an implicit cast from a 'char' 1618 // or 'short' to an 'int'. This is done because printf is a varargs 1619 // function. 1620 if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Ex)) 1621 if (ICE->getType() == S.Context.IntTy) 1622 if (ATR.matchesType(S.Context, ICE->getSubExpr()->getType())) 1623 return true; 1624 1625 // We may be able to offer a FixItHint if it is a supported type. 1626 PrintfSpecifier fixedFS = FS; 1627 bool success = fixedFS.fixType(Ex->getType()); 1628 1629 if (success) { 1630 // Get the fix string from the fixed format specifier 1631 llvm::SmallString<128> buf; 1632 llvm::raw_svector_ostream os(buf); 1633 fixedFS.toString(os); 1634 1635 // FIXME: getRepresentativeType() perhaps should return a string 1636 // instead of a QualType to better handle when the representative 1637 // type is 'wint_t' (which is defined in the system headers). 1638 S.Diag(getLocationOfByte(CS.getStart()), 1639 diag::warn_printf_conversion_argument_type_mismatch) 1640 << ATR.getRepresentativeType(S.Context) << Ex->getType() 1641 << getSpecifierRange(startSpecifier, specifierLen) 1642 << Ex->getSourceRange() 1643 << FixItHint::CreateReplacement( 1644 getSpecifierRange(startSpecifier, specifierLen), 1645 os.str()); 1646 } 1647 else { 1648 S.Diag(getLocationOfByte(CS.getStart()), 1649 diag::warn_printf_conversion_argument_type_mismatch) 1650 << ATR.getRepresentativeType(S.Context) << Ex->getType() 1651 << getSpecifierRange(startSpecifier, specifierLen) 1652 << Ex->getSourceRange(); 1653 } 1654 } 1655 1656 return true; 1657} 1658 1659//===--- CHECK: Scanf format string checking ------------------------------===// 1660 1661namespace { 1662class CheckScanfHandler : public CheckFormatHandler { 1663public: 1664 CheckScanfHandler(Sema &s, const StringLiteral *fexpr, 1665 const Expr *origFormatExpr, unsigned firstDataArg, 1666 unsigned numDataArgs, bool isObjCLiteral, 1667 const char *beg, bool hasVAListArg, 1668 const CallExpr *theCall, unsigned formatIdx) 1669 : CheckFormatHandler(s, fexpr, origFormatExpr, firstDataArg, 1670 numDataArgs, isObjCLiteral, beg, hasVAListArg, 1671 theCall, formatIdx) {} 1672 1673 bool HandleScanfSpecifier(const analyze_scanf::ScanfSpecifier &FS, 1674 const char *startSpecifier, 1675 unsigned specifierLen); 1676 1677 bool HandleInvalidScanfConversionSpecifier( 1678 const analyze_scanf::ScanfSpecifier &FS, 1679 const char *startSpecifier, 1680 unsigned specifierLen); 1681 1682 void HandleIncompleteScanList(const char *start, const char *end); 1683}; 1684} 1685 1686void CheckScanfHandler::HandleIncompleteScanList(const char *start, 1687 const char *end) { 1688 S.Diag(getLocationOfByte(end), diag::warn_scanf_scanlist_incomplete) 1689 << getSpecifierRange(start, end - start); 1690} 1691 1692bool CheckScanfHandler::HandleInvalidScanfConversionSpecifier( 1693 const analyze_scanf::ScanfSpecifier &FS, 1694 const char *startSpecifier, 1695 unsigned specifierLen) { 1696 1697 const analyze_scanf::ScanfConversionSpecifier &CS = 1698 FS.getConversionSpecifier(); 1699 1700 return HandleInvalidConversionSpecifier(FS.getArgIndex(), 1701 getLocationOfByte(CS.getStart()), 1702 startSpecifier, specifierLen, 1703 CS.getStart(), CS.getLength()); 1704} 1705 1706bool CheckScanfHandler::HandleScanfSpecifier( 1707 const analyze_scanf::ScanfSpecifier &FS, 1708 const char *startSpecifier, 1709 unsigned specifierLen) { 1710 1711 using namespace analyze_scanf; 1712 using namespace analyze_format_string; 1713 1714 const ScanfConversionSpecifier &CS = FS.getConversionSpecifier(); 1715 1716 // Handle case where '%' and '*' don't consume an argument. These shouldn't 1717 // be used to decide if we are using positional arguments consistently. 1718 if (FS.consumesDataArgument()) { 1719 if (atFirstArg) { 1720 atFirstArg = false; 1721 usesPositionalArgs = FS.usesPositionalArg(); 1722 } 1723 else if (usesPositionalArgs != FS.usesPositionalArg()) { 1724 // Cannot mix-and-match positional and non-positional arguments. 1725 S.Diag(getLocationOfByte(CS.getStart()), 1726 diag::warn_format_mix_positional_nonpositional_args) 1727 << getSpecifierRange(startSpecifier, specifierLen); 1728 return false; 1729 } 1730 } 1731 1732 // Check if the field with is non-zero. 1733 const OptionalAmount &Amt = FS.getFieldWidth(); 1734 if (Amt.getHowSpecified() == OptionalAmount::Constant) { 1735 if (Amt.getConstantAmount() == 0) { 1736 const CharSourceRange &R = getSpecifierRange(Amt.getStart(), 1737 Amt.getConstantLength()); 1738 S.Diag(getLocationOfByte(Amt.getStart()), 1739 diag::warn_scanf_nonzero_width) 1740 << R << FixItHint::CreateRemoval(R); 1741 } 1742 } 1743 1744 if (!FS.consumesDataArgument()) { 1745 // FIXME: Technically specifying a precision or field width here 1746 // makes no sense. Worth issuing a warning at some point. 1747 return true; 1748 } 1749 1750 // Consume the argument. 1751 unsigned argIndex = FS.getArgIndex(); 1752 if (argIndex < NumDataArgs) { 1753 // The check to see if the argIndex is valid will come later. 1754 // We set the bit here because we may exit early from this 1755 // function if we encounter some other error. 1756 CoveredArgs.set(argIndex); 1757 } 1758 1759 // Check the length modifier is valid with the given conversion specifier. 1760 const LengthModifier &LM = FS.getLengthModifier(); 1761 if (!FS.hasValidLengthModifier()) { 1762 S.Diag(getLocationOfByte(LM.getStart()), 1763 diag::warn_format_nonsensical_length) 1764 << LM.toString() << CS.toString() 1765 << getSpecifierRange(startSpecifier, specifierLen) 1766 << FixItHint::CreateRemoval(getSpecifierRange(LM.getStart(), 1767 LM.getLength())); 1768 } 1769 1770 // The remaining checks depend on the data arguments. 1771 if (HasVAListArg) 1772 return true; 1773 1774 if (!CheckNumArgs(FS, CS, startSpecifier, specifierLen, argIndex)) 1775 return false; 1776 1777 // FIXME: Check that the argument type matches the format specifier. 1778 1779 return true; 1780} 1781 1782void Sema::CheckFormatString(const StringLiteral *FExpr, 1783 const Expr *OrigFormatExpr, 1784 const CallExpr *TheCall, bool HasVAListArg, 1785 unsigned format_idx, unsigned firstDataArg, 1786 bool isPrintf) { 1787 1788 // CHECK: is the format string a wide literal? 1789 if (FExpr->isWide()) { 1790 Diag(FExpr->getLocStart(), 1791 diag::warn_format_string_is_wide_literal) 1792 << OrigFormatExpr->getSourceRange(); 1793 return; 1794 } 1795 1796 // Str - The format string. NOTE: this is NOT null-terminated! 1797 llvm::StringRef StrRef = FExpr->getString(); 1798 const char *Str = StrRef.data(); 1799 unsigned StrLen = StrRef.size(); 1800 1801 // CHECK: empty format string? 1802 if (StrLen == 0) { 1803 Diag(FExpr->getLocStart(), diag::warn_empty_format_string) 1804 << OrigFormatExpr->getSourceRange(); 1805 return; 1806 } 1807 1808 if (isPrintf) { 1809 CheckPrintfHandler H(*this, FExpr, OrigFormatExpr, firstDataArg, 1810 TheCall->getNumArgs() - firstDataArg, 1811 isa<ObjCStringLiteral>(OrigFormatExpr), Str, 1812 HasVAListArg, TheCall, format_idx); 1813 1814 bool FormatExtensions = getLangOptions().FormatExtensions; 1815 if (!analyze_format_string::ParsePrintfString(H, Str, Str + StrLen, 1816 FormatExtensions)) 1817 H.DoneProcessing(); 1818 } 1819 else { 1820 CheckScanfHandler H(*this, FExpr, OrigFormatExpr, firstDataArg, 1821 TheCall->getNumArgs() - firstDataArg, 1822 isa<ObjCStringLiteral>(OrigFormatExpr), Str, 1823 HasVAListArg, TheCall, format_idx); 1824 1825 if (!analyze_format_string::ParseScanfString(H, Str, Str + StrLen)) 1826 H.DoneProcessing(); 1827 } 1828} 1829 1830//===--- CHECK: Return Address of Stack Variable --------------------------===// 1831 1832static DeclRefExpr* EvalVal(Expr *E); 1833static DeclRefExpr* EvalAddr(Expr* E); 1834 1835/// CheckReturnStackAddr - Check if a return statement returns the address 1836/// of a stack variable. 1837void 1838Sema::CheckReturnStackAddr(Expr *RetValExp, QualType lhsType, 1839 SourceLocation ReturnLoc) { 1840 1841 // Perform checking for returned stack addresses. 1842 if (lhsType->isPointerType() || lhsType->isBlockPointerType()) { 1843 if (DeclRefExpr *DR = EvalAddr(RetValExp)) 1844 Diag(DR->getLocStart(), diag::warn_ret_stack_addr) 1845 << DR->getDecl()->getDeclName() << RetValExp->getSourceRange(); 1846 1847 // Skip over implicit cast expressions when checking for block expressions. 1848 RetValExp = RetValExp->IgnoreParenCasts(); 1849 1850 if (BlockExpr *C = dyn_cast<BlockExpr>(RetValExp)) 1851 if (C->hasBlockDeclRefExprs()) 1852 Diag(C->getLocStart(), diag::err_ret_local_block) 1853 << C->getSourceRange(); 1854 1855 if (AddrLabelExpr *ALE = dyn_cast<AddrLabelExpr>(RetValExp)) 1856 Diag(ALE->getLocStart(), diag::warn_ret_addr_label) 1857 << ALE->getSourceRange(); 1858 1859 } else if (lhsType->isReferenceType()) { 1860 // Perform checking for stack values returned by reference. 1861 // Check for a reference to the stack 1862 if (DeclRefExpr *DR = EvalVal(RetValExp)) 1863 Diag(DR->getLocStart(), diag::warn_ret_stack_ref) 1864 << DR->getDecl()->getDeclName() << RetValExp->getSourceRange(); 1865 } 1866} 1867 1868/// EvalAddr - EvalAddr and EvalVal are mutually recursive functions that 1869/// check if the expression in a return statement evaluates to an address 1870/// to a location on the stack. The recursion is used to traverse the 1871/// AST of the return expression, with recursion backtracking when we 1872/// encounter a subexpression that (1) clearly does not lead to the address 1873/// of a stack variable or (2) is something we cannot determine leads to 1874/// the address of a stack variable based on such local checking. 1875/// 1876/// EvalAddr processes expressions that are pointers that are used as 1877/// references (and not L-values). EvalVal handles all other values. 1878/// At the base case of the recursion is a check for a DeclRefExpr* in 1879/// the refers to a stack variable. 1880/// 1881/// This implementation handles: 1882/// 1883/// * pointer-to-pointer casts 1884/// * implicit conversions from array references to pointers 1885/// * taking the address of fields 1886/// * arbitrary interplay between "&" and "*" operators 1887/// * pointer arithmetic from an address of a stack variable 1888/// * taking the address of an array element where the array is on the stack 1889static DeclRefExpr* EvalAddr(Expr *E) { 1890 // We should only be called for evaluating pointer expressions. 1891 assert((E->getType()->isAnyPointerType() || 1892 E->getType()->isBlockPointerType() || 1893 E->getType()->isObjCQualifiedIdType()) && 1894 "EvalAddr only works on pointers"); 1895 1896 // Our "symbolic interpreter" is just a dispatch off the currently 1897 // viewed AST node. We then recursively traverse the AST by calling 1898 // EvalAddr and EvalVal appropriately. 1899 switch (E->getStmtClass()) { 1900 case Stmt::ParenExprClass: 1901 // Ignore parentheses. 1902 return EvalAddr(cast<ParenExpr>(E)->getSubExpr()); 1903 1904 case Stmt::UnaryOperatorClass: { 1905 // The only unary operator that make sense to handle here 1906 // is AddrOf. All others don't make sense as pointers. 1907 UnaryOperator *U = cast<UnaryOperator>(E); 1908 1909 if (U->getOpcode() == UO_AddrOf) 1910 return EvalVal(U->getSubExpr()); 1911 else 1912 return NULL; 1913 } 1914 1915 case Stmt::BinaryOperatorClass: { 1916 // Handle pointer arithmetic. All other binary operators are not valid 1917 // in this context. 1918 BinaryOperator *B = cast<BinaryOperator>(E); 1919 BinaryOperatorKind op = B->getOpcode(); 1920 1921 if (op != BO_Add && op != BO_Sub) 1922 return NULL; 1923 1924 Expr *Base = B->getLHS(); 1925 1926 // Determine which argument is the real pointer base. It could be 1927 // the RHS argument instead of the LHS. 1928 if (!Base->getType()->isPointerType()) Base = B->getRHS(); 1929 1930 assert (Base->getType()->isPointerType()); 1931 return EvalAddr(Base); 1932 } 1933 1934 // For conditional operators we need to see if either the LHS or RHS are 1935 // valid DeclRefExpr*s. If one of them is valid, we return it. 1936 case Stmt::ConditionalOperatorClass: { 1937 ConditionalOperator *C = cast<ConditionalOperator>(E); 1938 1939 // Handle the GNU extension for missing LHS. 1940 if (Expr *lhsExpr = C->getLHS()) 1941 if (DeclRefExpr* LHS = EvalAddr(lhsExpr)) 1942 return LHS; 1943 1944 return EvalAddr(C->getRHS()); 1945 } 1946 1947 // For casts, we need to handle conversions from arrays to 1948 // pointer values, and pointer-to-pointer conversions. 1949 case Stmt::ImplicitCastExprClass: 1950 case Stmt::CStyleCastExprClass: 1951 case Stmt::CXXFunctionalCastExprClass: { 1952 Expr* SubExpr = cast<CastExpr>(E)->getSubExpr(); 1953 QualType T = SubExpr->getType(); 1954 1955 if (SubExpr->getType()->isPointerType() || 1956 SubExpr->getType()->isBlockPointerType() || 1957 SubExpr->getType()->isObjCQualifiedIdType()) 1958 return EvalAddr(SubExpr); 1959 else if (T->isArrayType()) 1960 return EvalVal(SubExpr); 1961 else 1962 return 0; 1963 } 1964 1965 // C++ casts. For dynamic casts, static casts, and const casts, we 1966 // are always converting from a pointer-to-pointer, so we just blow 1967 // through the cast. In the case the dynamic cast doesn't fail (and 1968 // return NULL), we take the conservative route and report cases 1969 // where we return the address of a stack variable. For Reinterpre 1970 // FIXME: The comment about is wrong; we're not always converting 1971 // from pointer to pointer. I'm guessing that this code should also 1972 // handle references to objects. 1973 case Stmt::CXXStaticCastExprClass: 1974 case Stmt::CXXDynamicCastExprClass: 1975 case Stmt::CXXConstCastExprClass: 1976 case Stmt::CXXReinterpretCastExprClass: { 1977 Expr *S = cast<CXXNamedCastExpr>(E)->getSubExpr(); 1978 if (S->getType()->isPointerType() || S->getType()->isBlockPointerType()) 1979 return EvalAddr(S); 1980 else 1981 return NULL; 1982 } 1983 1984 // Everything else: we simply don't reason about them. 1985 default: 1986 return NULL; 1987 } 1988} 1989 1990 1991/// EvalVal - This function is complements EvalAddr in the mutual recursion. 1992/// See the comments for EvalAddr for more details. 1993static DeclRefExpr* EvalVal(Expr *E) { 1994do { 1995 // We should only be called for evaluating non-pointer expressions, or 1996 // expressions with a pointer type that are not used as references but instead 1997 // are l-values (e.g., DeclRefExpr with a pointer type). 1998 1999 // Our "symbolic interpreter" is just a dispatch off the currently 2000 // viewed AST node. We then recursively traverse the AST by calling 2001 // EvalAddr and EvalVal appropriately. 2002 switch (E->getStmtClass()) { 2003 case Stmt::ImplicitCastExprClass: { 2004 ImplicitCastExpr *IE = cast<ImplicitCastExpr>(E); 2005 if (IE->getValueKind() == VK_LValue) { 2006 E = IE->getSubExpr(); 2007 continue; 2008 } 2009 return NULL; 2010 } 2011 2012 case Stmt::DeclRefExprClass: { 2013 // DeclRefExpr: the base case. When we hit a DeclRefExpr we are looking 2014 // at code that refers to a variable's name. We check if it has local 2015 // storage within the function, and if so, return the expression. 2016 DeclRefExpr *DR = cast<DeclRefExpr>(E); 2017 2018 if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl())) 2019 if (V->hasLocalStorage() && !V->getType()->isReferenceType()) return DR; 2020 2021 return NULL; 2022 } 2023 2024 case Stmt::ParenExprClass: { 2025 // Ignore parentheses. 2026 E = cast<ParenExpr>(E)->getSubExpr(); 2027 continue; 2028 } 2029 2030 case Stmt::UnaryOperatorClass: { 2031 // The only unary operator that make sense to handle here 2032 // is Deref. All others don't resolve to a "name." This includes 2033 // handling all sorts of rvalues passed to a unary operator. 2034 UnaryOperator *U = cast<UnaryOperator>(E); 2035 2036 if (U->getOpcode() == UO_Deref) 2037 return EvalAddr(U->getSubExpr()); 2038 2039 return NULL; 2040 } 2041 2042 case Stmt::ArraySubscriptExprClass: { 2043 // Array subscripts are potential references to data on the stack. We 2044 // retrieve the DeclRefExpr* for the array variable if it indeed 2045 // has local storage. 2046 return EvalAddr(cast<ArraySubscriptExpr>(E)->getBase()); 2047 } 2048 2049 case Stmt::ConditionalOperatorClass: { 2050 // For conditional operators we need to see if either the LHS or RHS are 2051 // non-NULL DeclRefExpr's. If one is non-NULL, we return it. 2052 ConditionalOperator *C = cast<ConditionalOperator>(E); 2053 2054 // Handle the GNU extension for missing LHS. 2055 if (Expr *lhsExpr = C->getLHS()) 2056 if (DeclRefExpr *LHS = EvalVal(lhsExpr)) 2057 return LHS; 2058 2059 return EvalVal(C->getRHS()); 2060 } 2061 2062 // Accesses to members are potential references to data on the stack. 2063 case Stmt::MemberExprClass: { 2064 MemberExpr *M = cast<MemberExpr>(E); 2065 2066 // Check for indirect access. We only want direct field accesses. 2067 if (M->isArrow()) 2068 return NULL; 2069 2070 // Check whether the member type is itself a reference, in which case 2071 // we're not going to refer to the member, but to what the member refers to. 2072 if (M->getMemberDecl()->getType()->isReferenceType()) 2073 return NULL; 2074 2075 return EvalVal(M->getBase()); 2076 } 2077 2078 // Everything else: we simply don't reason about them. 2079 default: 2080 return NULL; 2081 } 2082} while (true); 2083} 2084 2085//===--- CHECK: Floating-Point comparisons (-Wfloat-equal) ---------------===// 2086 2087/// Check for comparisons of floating point operands using != and ==. 2088/// Issue a warning if these are no self-comparisons, as they are not likely 2089/// to do what the programmer intended. 2090void Sema::CheckFloatComparison(SourceLocation loc, Expr* lex, Expr *rex) { 2091 bool EmitWarning = true; 2092 2093 Expr* LeftExprSansParen = lex->IgnoreParens(); 2094 Expr* RightExprSansParen = rex->IgnoreParens(); 2095 2096 // Special case: check for x == x (which is OK). 2097 // Do not emit warnings for such cases. 2098 if (DeclRefExpr* DRL = dyn_cast<DeclRefExpr>(LeftExprSansParen)) 2099 if (DeclRefExpr* DRR = dyn_cast<DeclRefExpr>(RightExprSansParen)) 2100 if (DRL->getDecl() == DRR->getDecl()) 2101 EmitWarning = false; 2102 2103 2104 // Special case: check for comparisons against literals that can be exactly 2105 // represented by APFloat. In such cases, do not emit a warning. This 2106 // is a heuristic: often comparison against such literals are used to 2107 // detect if a value in a variable has not changed. This clearly can 2108 // lead to false negatives. 2109 if (EmitWarning) { 2110 if (FloatingLiteral* FLL = dyn_cast<FloatingLiteral>(LeftExprSansParen)) { 2111 if (FLL->isExact()) 2112 EmitWarning = false; 2113 } else 2114 if (FloatingLiteral* FLR = dyn_cast<FloatingLiteral>(RightExprSansParen)){ 2115 if (FLR->isExact()) 2116 EmitWarning = false; 2117 } 2118 } 2119 2120 // Check for comparisons with builtin types. 2121 if (EmitWarning) 2122 if (CallExpr* CL = dyn_cast<CallExpr>(LeftExprSansParen)) 2123 if (CL->isBuiltinCall(Context)) 2124 EmitWarning = false; 2125 2126 if (EmitWarning) 2127 if (CallExpr* CR = dyn_cast<CallExpr>(RightExprSansParen)) 2128 if (CR->isBuiltinCall(Context)) 2129 EmitWarning = false; 2130 2131 // Emit the diagnostic. 2132 if (EmitWarning) 2133 Diag(loc, diag::warn_floatingpoint_eq) 2134 << lex->getSourceRange() << rex->getSourceRange(); 2135} 2136 2137//===--- CHECK: Integer mixed-sign comparisons (-Wsign-compare) --------===// 2138//===--- CHECK: Lossy implicit conversions (-Wconversion) --------------===// 2139 2140namespace { 2141 2142/// Structure recording the 'active' range of an integer-valued 2143/// expression. 2144struct IntRange { 2145 /// The number of bits active in the int. 2146 unsigned Width; 2147 2148 /// True if the int is known not to have negative values. 2149 bool NonNegative; 2150 2151 IntRange(unsigned Width, bool NonNegative) 2152 : Width(Width), NonNegative(NonNegative) 2153 {} 2154 2155 // Returns the range of the bool type. 2156 static IntRange forBoolType() { 2157 return IntRange(1, true); 2158 } 2159 2160 // Returns the range of an integral type. 2161 static IntRange forType(ASTContext &C, QualType T) { 2162 return forCanonicalType(C, T->getCanonicalTypeInternal().getTypePtr()); 2163 } 2164 2165 // Returns the range of an integeral type based on its canonical 2166 // representation. 2167 static IntRange forCanonicalType(ASTContext &C, const Type *T) { 2168 assert(T->isCanonicalUnqualified()); 2169 2170 if (const VectorType *VT = dyn_cast<VectorType>(T)) 2171 T = VT->getElementType().getTypePtr(); 2172 if (const ComplexType *CT = dyn_cast<ComplexType>(T)) 2173 T = CT->getElementType().getTypePtr(); 2174 2175 if (const EnumType *ET = dyn_cast<EnumType>(T)) { 2176 EnumDecl *Enum = ET->getDecl(); 2177 unsigned NumPositive = Enum->getNumPositiveBits(); 2178 unsigned NumNegative = Enum->getNumNegativeBits(); 2179 2180 return IntRange(std::max(NumPositive, NumNegative), NumNegative == 0); 2181 } 2182 2183 const BuiltinType *BT = cast<BuiltinType>(T); 2184 assert(BT->isInteger()); 2185 2186 return IntRange(C.getIntWidth(QualType(T, 0)), BT->isUnsignedInteger()); 2187 } 2188 2189 // Returns the supremum of two ranges: i.e. their conservative merge. 2190 static IntRange join(IntRange L, IntRange R) { 2191 return IntRange(std::max(L.Width, R.Width), 2192 L.NonNegative && R.NonNegative); 2193 } 2194 2195 // Returns the infinum of two ranges: i.e. their aggressive merge. 2196 static IntRange meet(IntRange L, IntRange R) { 2197 return IntRange(std::min(L.Width, R.Width), 2198 L.NonNegative || R.NonNegative); 2199 } 2200}; 2201 2202IntRange GetValueRange(ASTContext &C, llvm::APSInt &value, unsigned MaxWidth) { 2203 if (value.isSigned() && value.isNegative()) 2204 return IntRange(value.getMinSignedBits(), false); 2205 2206 if (value.getBitWidth() > MaxWidth) 2207 value.trunc(MaxWidth); 2208 2209 // isNonNegative() just checks the sign bit without considering 2210 // signedness. 2211 return IntRange(value.getActiveBits(), true); 2212} 2213 2214IntRange GetValueRange(ASTContext &C, APValue &result, QualType Ty, 2215 unsigned MaxWidth) { 2216 if (result.isInt()) 2217 return GetValueRange(C, result.getInt(), MaxWidth); 2218 2219 if (result.isVector()) { 2220 IntRange R = GetValueRange(C, result.getVectorElt(0), Ty, MaxWidth); 2221 for (unsigned i = 1, e = result.getVectorLength(); i != e; ++i) { 2222 IntRange El = GetValueRange(C, result.getVectorElt(i), Ty, MaxWidth); 2223 R = IntRange::join(R, El); 2224 } 2225 return R; 2226 } 2227 2228 if (result.isComplexInt()) { 2229 IntRange R = GetValueRange(C, result.getComplexIntReal(), MaxWidth); 2230 IntRange I = GetValueRange(C, result.getComplexIntImag(), MaxWidth); 2231 return IntRange::join(R, I); 2232 } 2233 2234 // This can happen with lossless casts to intptr_t of "based" lvalues. 2235 // Assume it might use arbitrary bits. 2236 // FIXME: The only reason we need to pass the type in here is to get 2237 // the sign right on this one case. It would be nice if APValue 2238 // preserved this. 2239 assert(result.isLValue()); 2240 return IntRange(MaxWidth, Ty->isUnsignedIntegerType()); 2241} 2242 2243/// Pseudo-evaluate the given integer expression, estimating the 2244/// range of values it might take. 2245/// 2246/// \param MaxWidth - the width to which the value will be truncated 2247IntRange GetExprRange(ASTContext &C, Expr *E, unsigned MaxWidth) { 2248 E = E->IgnoreParens(); 2249 2250 // Try a full evaluation first. 2251 Expr::EvalResult result; 2252 if (E->Evaluate(result, C)) 2253 return GetValueRange(C, result.Val, E->getType(), MaxWidth); 2254 2255 // I think we only want to look through implicit casts here; if the 2256 // user has an explicit widening cast, we should treat the value as 2257 // being of the new, wider type. 2258 if (ImplicitCastExpr *CE = dyn_cast<ImplicitCastExpr>(E)) { 2259 if (CE->getCastKind() == CK_NoOp) 2260 return GetExprRange(C, CE->getSubExpr(), MaxWidth); 2261 2262 IntRange OutputTypeRange = IntRange::forType(C, CE->getType()); 2263 2264 bool isIntegerCast = (CE->getCastKind() == CK_IntegralCast); 2265 if (!isIntegerCast && CE->getCastKind() == CK_Unknown) 2266 isIntegerCast = CE->getSubExpr()->getType()->isIntegerType(); 2267 2268 // Assume that non-integer casts can span the full range of the type. 2269 if (!isIntegerCast) 2270 return OutputTypeRange; 2271 2272 IntRange SubRange 2273 = GetExprRange(C, CE->getSubExpr(), 2274 std::min(MaxWidth, OutputTypeRange.Width)); 2275 2276 // Bail out if the subexpr's range is as wide as the cast type. 2277 if (SubRange.Width >= OutputTypeRange.Width) 2278 return OutputTypeRange; 2279 2280 // Otherwise, we take the smaller width, and we're non-negative if 2281 // either the output type or the subexpr is. 2282 return IntRange(SubRange.Width, 2283 SubRange.NonNegative || OutputTypeRange.NonNegative); 2284 } 2285 2286 if (ConditionalOperator *CO = dyn_cast<ConditionalOperator>(E)) { 2287 // If we can fold the condition, just take that operand. 2288 bool CondResult; 2289 if (CO->getCond()->EvaluateAsBooleanCondition(CondResult, C)) 2290 return GetExprRange(C, CondResult ? CO->getTrueExpr() 2291 : CO->getFalseExpr(), 2292 MaxWidth); 2293 2294 // Otherwise, conservatively merge. 2295 IntRange L = GetExprRange(C, CO->getTrueExpr(), MaxWidth); 2296 IntRange R = GetExprRange(C, CO->getFalseExpr(), MaxWidth); 2297 return IntRange::join(L, R); 2298 } 2299 2300 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) { 2301 switch (BO->getOpcode()) { 2302 2303 // Boolean-valued operations are single-bit and positive. 2304 case BO_LAnd: 2305 case BO_LOr: 2306 case BO_LT: 2307 case BO_GT: 2308 case BO_LE: 2309 case BO_GE: 2310 case BO_EQ: 2311 case BO_NE: 2312 return IntRange::forBoolType(); 2313 2314 // The type of these compound assignments is the type of the LHS, 2315 // so the RHS is not necessarily an integer. 2316 case BO_MulAssign: 2317 case BO_DivAssign: 2318 case BO_RemAssign: 2319 case BO_AddAssign: 2320 case BO_SubAssign: 2321 return IntRange::forType(C, E->getType()); 2322 2323 // Operations with opaque sources are black-listed. 2324 case BO_PtrMemD: 2325 case BO_PtrMemI: 2326 return IntRange::forType(C, E->getType()); 2327 2328 // Bitwise-and uses the *infinum* of the two source ranges. 2329 case BO_And: 2330 case BO_AndAssign: 2331 return IntRange::meet(GetExprRange(C, BO->getLHS(), MaxWidth), 2332 GetExprRange(C, BO->getRHS(), MaxWidth)); 2333 2334 // Left shift gets black-listed based on a judgement call. 2335 case BO_Shl: 2336 // ...except that we want to treat '1 << (blah)' as logically 2337 // positive. It's an important idiom. 2338 if (IntegerLiteral *I 2339 = dyn_cast<IntegerLiteral>(BO->getLHS()->IgnoreParenCasts())) { 2340 if (I->getValue() == 1) { 2341 IntRange R = IntRange::forType(C, E->getType()); 2342 return IntRange(R.Width, /*NonNegative*/ true); 2343 } 2344 } 2345 // fallthrough 2346 2347 case BO_ShlAssign: 2348 return IntRange::forType(C, E->getType()); 2349 2350 // Right shift by a constant can narrow its left argument. 2351 case BO_Shr: 2352 case BO_ShrAssign: { 2353 IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth); 2354 2355 // If the shift amount is a positive constant, drop the width by 2356 // that much. 2357 llvm::APSInt shift; 2358 if (BO->getRHS()->isIntegerConstantExpr(shift, C) && 2359 shift.isNonNegative()) { 2360 unsigned zext = shift.getZExtValue(); 2361 if (zext >= L.Width) 2362 L.Width = (L.NonNegative ? 0 : 1); 2363 else 2364 L.Width -= zext; 2365 } 2366 2367 return L; 2368 } 2369 2370 // Comma acts as its right operand. 2371 case BO_Comma: 2372 return GetExprRange(C, BO->getRHS(), MaxWidth); 2373 2374 // Black-list pointer subtractions. 2375 case BO_Sub: 2376 if (BO->getLHS()->getType()->isPointerType()) 2377 return IntRange::forType(C, E->getType()); 2378 // fallthrough 2379 2380 default: 2381 break; 2382 } 2383 2384 // Treat every other operator as if it were closed on the 2385 // narrowest type that encompasses both operands. 2386 IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth); 2387 IntRange R = GetExprRange(C, BO->getRHS(), MaxWidth); 2388 return IntRange::join(L, R); 2389 } 2390 2391 if (UnaryOperator *UO = dyn_cast<UnaryOperator>(E)) { 2392 switch (UO->getOpcode()) { 2393 // Boolean-valued operations are white-listed. 2394 case UO_LNot: 2395 return IntRange::forBoolType(); 2396 2397 // Operations with opaque sources are black-listed. 2398 case UO_Deref: 2399 case UO_AddrOf: // should be impossible 2400 return IntRange::forType(C, E->getType()); 2401 2402 default: 2403 return GetExprRange(C, UO->getSubExpr(), MaxWidth); 2404 } 2405 } 2406 2407 if (dyn_cast<OffsetOfExpr>(E)) { 2408 IntRange::forType(C, E->getType()); 2409 } 2410 2411 FieldDecl *BitField = E->getBitField(); 2412 if (BitField) { 2413 llvm::APSInt BitWidthAP = BitField->getBitWidth()->EvaluateAsInt(C); 2414 unsigned BitWidth = BitWidthAP.getZExtValue(); 2415 2416 return IntRange(BitWidth, BitField->getType()->isUnsignedIntegerType()); 2417 } 2418 2419 return IntRange::forType(C, E->getType()); 2420} 2421 2422IntRange GetExprRange(ASTContext &C, Expr *E) { 2423 return GetExprRange(C, E, C.getIntWidth(E->getType())); 2424} 2425 2426/// Checks whether the given value, which currently has the given 2427/// source semantics, has the same value when coerced through the 2428/// target semantics. 2429bool IsSameFloatAfterCast(const llvm::APFloat &value, 2430 const llvm::fltSemantics &Src, 2431 const llvm::fltSemantics &Tgt) { 2432 llvm::APFloat truncated = value; 2433 2434 bool ignored; 2435 truncated.convert(Src, llvm::APFloat::rmNearestTiesToEven, &ignored); 2436 truncated.convert(Tgt, llvm::APFloat::rmNearestTiesToEven, &ignored); 2437 2438 return truncated.bitwiseIsEqual(value); 2439} 2440 2441/// Checks whether the given value, which currently has the given 2442/// source semantics, has the same value when coerced through the 2443/// target semantics. 2444/// 2445/// The value might be a vector of floats (or a complex number). 2446bool IsSameFloatAfterCast(const APValue &value, 2447 const llvm::fltSemantics &Src, 2448 const llvm::fltSemantics &Tgt) { 2449 if (value.isFloat()) 2450 return IsSameFloatAfterCast(value.getFloat(), Src, Tgt); 2451 2452 if (value.isVector()) { 2453 for (unsigned i = 0, e = value.getVectorLength(); i != e; ++i) 2454 if (!IsSameFloatAfterCast(value.getVectorElt(i), Src, Tgt)) 2455 return false; 2456 return true; 2457 } 2458 2459 assert(value.isComplexFloat()); 2460 return (IsSameFloatAfterCast(value.getComplexFloatReal(), Src, Tgt) && 2461 IsSameFloatAfterCast(value.getComplexFloatImag(), Src, Tgt)); 2462} 2463 2464void AnalyzeImplicitConversions(Sema &S, Expr *E); 2465 2466bool IsZero(Sema &S, Expr *E) { 2467 llvm::APSInt Value; 2468 return E->isIntegerConstantExpr(Value, S.Context) && Value == 0; 2469} 2470 2471void CheckTrivialUnsignedComparison(Sema &S, BinaryOperator *E) { 2472 BinaryOperatorKind op = E->getOpcode(); 2473 if (op == BO_LT && IsZero(S, E->getRHS())) { 2474 S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison) 2475 << "< 0" << "false" 2476 << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); 2477 } else if (op == BO_GE && IsZero(S, E->getRHS())) { 2478 S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison) 2479 << ">= 0" << "true" 2480 << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); 2481 } else if (op == BO_GT && IsZero(S, E->getLHS())) { 2482 S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison) 2483 << "0 >" << "false" 2484 << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); 2485 } else if (op == BO_LE && IsZero(S, E->getLHS())) { 2486 S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison) 2487 << "0 <=" << "true" 2488 << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); 2489 } 2490} 2491 2492/// Analyze the operands of the given comparison. Implements the 2493/// fallback case from AnalyzeComparison. 2494void AnalyzeImpConvsInComparison(Sema &S, BinaryOperator *E) { 2495 AnalyzeImplicitConversions(S, E->getLHS()); 2496 AnalyzeImplicitConversions(S, E->getRHS()); 2497} 2498 2499/// \brief Implements -Wsign-compare. 2500/// 2501/// \param lex the left-hand expression 2502/// \param rex the right-hand expression 2503/// \param OpLoc the location of the joining operator 2504/// \param BinOpc binary opcode or 0 2505void AnalyzeComparison(Sema &S, BinaryOperator *E) { 2506 // The type the comparison is being performed in. 2507 QualType T = E->getLHS()->getType(); 2508 assert(S.Context.hasSameUnqualifiedType(T, E->getRHS()->getType()) 2509 && "comparison with mismatched types"); 2510 2511 // We don't do anything special if this isn't an unsigned integral 2512 // comparison: we're only interested in integral comparisons, and 2513 // signed comparisons only happen in cases we don't care to warn about. 2514 if (!T->hasUnsignedIntegerRepresentation()) 2515 return AnalyzeImpConvsInComparison(S, E); 2516 2517 Expr *lex = E->getLHS()->IgnoreParenImpCasts(); 2518 Expr *rex = E->getRHS()->IgnoreParenImpCasts(); 2519 2520 // Check to see if one of the (unmodified) operands is of different 2521 // signedness. 2522 Expr *signedOperand, *unsignedOperand; 2523 if (lex->getType()->hasSignedIntegerRepresentation()) { 2524 assert(!rex->getType()->hasSignedIntegerRepresentation() && 2525 "unsigned comparison between two signed integer expressions?"); 2526 signedOperand = lex; 2527 unsignedOperand = rex; 2528 } else if (rex->getType()->hasSignedIntegerRepresentation()) { 2529 signedOperand = rex; 2530 unsignedOperand = lex; 2531 } else { 2532 CheckTrivialUnsignedComparison(S, E); 2533 return AnalyzeImpConvsInComparison(S, E); 2534 } 2535 2536 // Otherwise, calculate the effective range of the signed operand. 2537 IntRange signedRange = GetExprRange(S.Context, signedOperand); 2538 2539 // Go ahead and analyze implicit conversions in the operands. Note 2540 // that we skip the implicit conversions on both sides. 2541 AnalyzeImplicitConversions(S, lex); 2542 AnalyzeImplicitConversions(S, rex); 2543 2544 // If the signed range is non-negative, -Wsign-compare won't fire, 2545 // but we should still check for comparisons which are always true 2546 // or false. 2547 if (signedRange.NonNegative) 2548 return CheckTrivialUnsignedComparison(S, E); 2549 2550 // For (in)equality comparisons, if the unsigned operand is a 2551 // constant which cannot collide with a overflowed signed operand, 2552 // then reinterpreting the signed operand as unsigned will not 2553 // change the result of the comparison. 2554 if (E->isEqualityOp()) { 2555 unsigned comparisonWidth = S.Context.getIntWidth(T); 2556 IntRange unsignedRange = GetExprRange(S.Context, unsignedOperand); 2557 2558 // We should never be unable to prove that the unsigned operand is 2559 // non-negative. 2560 assert(unsignedRange.NonNegative && "unsigned range includes negative?"); 2561 2562 if (unsignedRange.Width < comparisonWidth) 2563 return; 2564 } 2565 2566 S.Diag(E->getOperatorLoc(), diag::warn_mixed_sign_comparison) 2567 << lex->getType() << rex->getType() 2568 << lex->getSourceRange() << rex->getSourceRange(); 2569} 2570 2571/// Diagnose an implicit cast; purely a helper for CheckImplicitConversion. 2572void DiagnoseImpCast(Sema &S, Expr *E, QualType T, unsigned diag) { 2573 S.Diag(E->getExprLoc(), diag) << E->getType() << T << E->getSourceRange(); 2574} 2575 2576void CheckImplicitConversion(Sema &S, Expr *E, QualType T, 2577 bool *ICContext = 0) { 2578 if (E->isTypeDependent() || E->isValueDependent()) return; 2579 2580 const Type *Source = S.Context.getCanonicalType(E->getType()).getTypePtr(); 2581 const Type *Target = S.Context.getCanonicalType(T).getTypePtr(); 2582 if (Source == Target) return; 2583 if (Target->isDependentType()) return; 2584 2585 // Never diagnose implicit casts to bool. 2586 if (Target->isSpecificBuiltinType(BuiltinType::Bool)) 2587 return; 2588 2589 // Strip vector types. 2590 if (isa<VectorType>(Source)) { 2591 if (!isa<VectorType>(Target)) 2592 return DiagnoseImpCast(S, E, T, diag::warn_impcast_vector_scalar); 2593 2594 Source = cast<VectorType>(Source)->getElementType().getTypePtr(); 2595 Target = cast<VectorType>(Target)->getElementType().getTypePtr(); 2596 } 2597 2598 // Strip complex types. 2599 if (isa<ComplexType>(Source)) { 2600 if (!isa<ComplexType>(Target)) 2601 return DiagnoseImpCast(S, E, T, diag::warn_impcast_complex_scalar); 2602 2603 Source = cast<ComplexType>(Source)->getElementType().getTypePtr(); 2604 Target = cast<ComplexType>(Target)->getElementType().getTypePtr(); 2605 } 2606 2607 const BuiltinType *SourceBT = dyn_cast<BuiltinType>(Source); 2608 const BuiltinType *TargetBT = dyn_cast<BuiltinType>(Target); 2609 2610 // If the source is floating point... 2611 if (SourceBT && SourceBT->isFloatingPoint()) { 2612 // ...and the target is floating point... 2613 if (TargetBT && TargetBT->isFloatingPoint()) { 2614 // ...then warn if we're dropping FP rank. 2615 2616 // Builtin FP kinds are ordered by increasing FP rank. 2617 if (SourceBT->getKind() > TargetBT->getKind()) { 2618 // Don't warn about float constants that are precisely 2619 // representable in the target type. 2620 Expr::EvalResult result; 2621 if (E->Evaluate(result, S.Context)) { 2622 // Value might be a float, a float vector, or a float complex. 2623 if (IsSameFloatAfterCast(result.Val, 2624 S.Context.getFloatTypeSemantics(QualType(TargetBT, 0)), 2625 S.Context.getFloatTypeSemantics(QualType(SourceBT, 0)))) 2626 return; 2627 } 2628 2629 DiagnoseImpCast(S, E, T, diag::warn_impcast_float_precision); 2630 } 2631 return; 2632 } 2633 2634 // If the target is integral, always warn. 2635 if ((TargetBT && TargetBT->isInteger())) 2636 // TODO: don't warn for integer values? 2637 DiagnoseImpCast(S, E, T, diag::warn_impcast_float_integer); 2638 2639 return; 2640 } 2641 2642 if (!Source->isIntegerType() || !Target->isIntegerType()) 2643 return; 2644 2645 IntRange SourceRange = GetExprRange(S.Context, E); 2646 IntRange TargetRange = IntRange::forCanonicalType(S.Context, Target); 2647 2648 if (SourceRange.Width > TargetRange.Width) { 2649 // People want to build with -Wshorten-64-to-32 and not -Wconversion 2650 // and by god we'll let them. 2651 if (SourceRange.Width == 64 && TargetRange.Width == 32) 2652 return DiagnoseImpCast(S, E, T, diag::warn_impcast_integer_64_32); 2653 return DiagnoseImpCast(S, E, T, diag::warn_impcast_integer_precision); 2654 } 2655 2656 if ((TargetRange.NonNegative && !SourceRange.NonNegative) || 2657 (!TargetRange.NonNegative && SourceRange.NonNegative && 2658 SourceRange.Width == TargetRange.Width)) { 2659 unsigned DiagID = diag::warn_impcast_integer_sign; 2660 2661 // Traditionally, gcc has warned about this under -Wsign-compare. 2662 // We also want to warn about it in -Wconversion. 2663 // So if -Wconversion is off, use a completely identical diagnostic 2664 // in the sign-compare group. 2665 // The conditional-checking code will 2666 if (ICContext) { 2667 DiagID = diag::warn_impcast_integer_sign_conditional; 2668 *ICContext = true; 2669 } 2670 2671 return DiagnoseImpCast(S, E, T, DiagID); 2672 } 2673 2674 return; 2675} 2676 2677void CheckConditionalOperator(Sema &S, ConditionalOperator *E, QualType T); 2678 2679void CheckConditionalOperand(Sema &S, Expr *E, QualType T, 2680 bool &ICContext) { 2681 E = E->IgnoreParenImpCasts(); 2682 2683 if (isa<ConditionalOperator>(E)) 2684 return CheckConditionalOperator(S, cast<ConditionalOperator>(E), T); 2685 2686 AnalyzeImplicitConversions(S, E); 2687 if (E->getType() != T) 2688 return CheckImplicitConversion(S, E, T, &ICContext); 2689 return; 2690} 2691 2692void CheckConditionalOperator(Sema &S, ConditionalOperator *E, QualType T) { 2693 AnalyzeImplicitConversions(S, E->getCond()); 2694 2695 bool Suspicious = false; 2696 CheckConditionalOperand(S, E->getTrueExpr(), T, Suspicious); 2697 CheckConditionalOperand(S, E->getFalseExpr(), T, Suspicious); 2698 2699 // If -Wconversion would have warned about either of the candidates 2700 // for a signedness conversion to the context type... 2701 if (!Suspicious) return; 2702 2703 // ...but it's currently ignored... 2704 if (S.Diags.getDiagnosticLevel(diag::warn_impcast_integer_sign_conditional)) 2705 return; 2706 2707 // ...and -Wsign-compare isn't... 2708 if (!S.Diags.getDiagnosticLevel(diag::warn_mixed_sign_conditional)) 2709 return; 2710 2711 // ...then check whether it would have warned about either of the 2712 // candidates for a signedness conversion to the condition type. 2713 if (E->getType() != T) { 2714 Suspicious = false; 2715 CheckImplicitConversion(S, E->getTrueExpr()->IgnoreParenImpCasts(), 2716 E->getType(), &Suspicious); 2717 if (!Suspicious) 2718 CheckImplicitConversion(S, E->getFalseExpr()->IgnoreParenImpCasts(), 2719 E->getType(), &Suspicious); 2720 if (!Suspicious) 2721 return; 2722 } 2723 2724 // If so, emit a diagnostic under -Wsign-compare. 2725 Expr *lex = E->getTrueExpr()->IgnoreParenImpCasts(); 2726 Expr *rex = E->getFalseExpr()->IgnoreParenImpCasts(); 2727 S.Diag(E->getQuestionLoc(), diag::warn_mixed_sign_conditional) 2728 << lex->getType() << rex->getType() 2729 << lex->getSourceRange() << rex->getSourceRange(); 2730} 2731 2732/// AnalyzeImplicitConversions - Find and report any interesting 2733/// implicit conversions in the given expression. There are a couple 2734/// of competing diagnostics here, -Wconversion and -Wsign-compare. 2735void AnalyzeImplicitConversions(Sema &S, Expr *OrigE) { 2736 QualType T = OrigE->getType(); 2737 Expr *E = OrigE->IgnoreParenImpCasts(); 2738 2739 // For conditional operators, we analyze the arguments as if they 2740 // were being fed directly into the output. 2741 if (isa<ConditionalOperator>(E)) { 2742 ConditionalOperator *CO = cast<ConditionalOperator>(E); 2743 CheckConditionalOperator(S, CO, T); 2744 return; 2745 } 2746 2747 // Go ahead and check any implicit conversions we might have skipped. 2748 // The non-canonical typecheck is just an optimization; 2749 // CheckImplicitConversion will filter out dead implicit conversions. 2750 if (E->getType() != T) 2751 CheckImplicitConversion(S, E, T); 2752 2753 // Now continue drilling into this expression. 2754 2755 // Skip past explicit casts. 2756 if (isa<ExplicitCastExpr>(E)) { 2757 E = cast<ExplicitCastExpr>(E)->getSubExpr()->IgnoreParenImpCasts(); 2758 return AnalyzeImplicitConversions(S, E); 2759 } 2760 2761 // Do a somewhat different check with comparison operators. 2762 if (isa<BinaryOperator>(E) && cast<BinaryOperator>(E)->isComparisonOp()) 2763 return AnalyzeComparison(S, cast<BinaryOperator>(E)); 2764 2765 // These break the otherwise-useful invariant below. Fortunately, 2766 // we don't really need to recurse into them, because any internal 2767 // expressions should have been analyzed already when they were 2768 // built into statements. 2769 if (isa<StmtExpr>(E)) return; 2770 2771 // Don't descend into unevaluated contexts. 2772 if (isa<SizeOfAlignOfExpr>(E)) return; 2773 2774 // Now just recurse over the expression's children. 2775 for (Stmt::child_iterator I = E->child_begin(), IE = E->child_end(); 2776 I != IE; ++I) 2777 AnalyzeImplicitConversions(S, cast<Expr>(*I)); 2778} 2779 2780} // end anonymous namespace 2781 2782/// Diagnoses "dangerous" implicit conversions within the given 2783/// expression (which is a full expression). Implements -Wconversion 2784/// and -Wsign-compare. 2785void Sema::CheckImplicitConversions(Expr *E) { 2786 // Don't diagnose in unevaluated contexts. 2787 if (ExprEvalContexts.back().Context == Sema::Unevaluated) 2788 return; 2789 2790 // Don't diagnose for value- or type-dependent expressions. 2791 if (E->isTypeDependent() || E->isValueDependent()) 2792 return; 2793 2794 AnalyzeImplicitConversions(*this, E); 2795} 2796 2797/// CheckParmsForFunctionDef - Check that the parameters of the given 2798/// function are appropriate for the definition of a function. This 2799/// takes care of any checks that cannot be performed on the 2800/// declaration itself, e.g., that the types of each of the function 2801/// parameters are complete. 2802bool Sema::CheckParmsForFunctionDef(FunctionDecl *FD) { 2803 bool HasInvalidParm = false; 2804 for (unsigned p = 0, NumParams = FD->getNumParams(); p < NumParams; ++p) { 2805 ParmVarDecl *Param = FD->getParamDecl(p); 2806 2807 // C99 6.7.5.3p4: the parameters in a parameter type list in a 2808 // function declarator that is part of a function definition of 2809 // that function shall not have incomplete type. 2810 // 2811 // This is also C++ [dcl.fct]p6. 2812 if (!Param->isInvalidDecl() && 2813 RequireCompleteType(Param->getLocation(), Param->getType(), 2814 diag::err_typecheck_decl_incomplete_type)) { 2815 Param->setInvalidDecl(); 2816 HasInvalidParm = true; 2817 } 2818 2819 // C99 6.9.1p5: If the declarator includes a parameter type list, the 2820 // declaration of each parameter shall include an identifier. 2821 if (Param->getIdentifier() == 0 && 2822 !Param->isImplicit() && 2823 !getLangOptions().CPlusPlus) 2824 Diag(Param->getLocation(), diag::err_parameter_name_omitted); 2825 2826 // C99 6.7.5.3p12: 2827 // If the function declarator is not part of a definition of that 2828 // function, parameters may have incomplete type and may use the [*] 2829 // notation in their sequences of declarator specifiers to specify 2830 // variable length array types. 2831 QualType PType = Param->getOriginalType(); 2832 if (const ArrayType *AT = Context.getAsArrayType(PType)) { 2833 if (AT->getSizeModifier() == ArrayType::Star) { 2834 // FIXME: This diagnosic should point the the '[*]' if source-location 2835 // information is added for it. 2836 Diag(Param->getLocation(), diag::err_array_star_in_function_definition); 2837 } 2838 } 2839 } 2840 2841 return HasInvalidParm; 2842} 2843 2844/// CheckCastAlign - Implements -Wcast-align, which warns when a 2845/// pointer cast increases the alignment requirements. 2846void Sema::CheckCastAlign(Expr *Op, QualType T, SourceRange TRange) { 2847 // This is actually a lot of work to potentially be doing on every 2848 // cast; don't do it if we're ignoring -Wcast_align (as is the default). 2849 if (getDiagnostics().getDiagnosticLevel(diag::warn_cast_align) 2850 == Diagnostic::Ignored) 2851 return; 2852 2853 // Ignore dependent types. 2854 if (T->isDependentType() || Op->getType()->isDependentType()) 2855 return; 2856 2857 // Require that the destination be a pointer type. 2858 const PointerType *DestPtr = T->getAs<PointerType>(); 2859 if (!DestPtr) return; 2860 2861 // If the destination has alignment 1, we're done. 2862 QualType DestPointee = DestPtr->getPointeeType(); 2863 if (DestPointee->isIncompleteType()) return; 2864 CharUnits DestAlign = Context.getTypeAlignInChars(DestPointee); 2865 if (DestAlign.isOne()) return; 2866 2867 // Require that the source be a pointer type. 2868 const PointerType *SrcPtr = Op->getType()->getAs<PointerType>(); 2869 if (!SrcPtr) return; 2870 QualType SrcPointee = SrcPtr->getPointeeType(); 2871 2872 // Whitelist casts from cv void*. We already implicitly 2873 // whitelisted casts to cv void*, since they have alignment 1. 2874 // Also whitelist casts involving incomplete types, which implicitly 2875 // includes 'void'. 2876 if (SrcPointee->isIncompleteType()) return; 2877 2878 CharUnits SrcAlign = Context.getTypeAlignInChars(SrcPointee); 2879 if (SrcAlign >= DestAlign) return; 2880 2881 Diag(TRange.getBegin(), diag::warn_cast_align) 2882 << Op->getType() << T 2883 << static_cast<unsigned>(SrcAlign.getQuantity()) 2884 << static_cast<unsigned>(DestAlign.getQuantity()) 2885 << TRange << Op->getSourceRange(); 2886} 2887 2888