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Diffstat (limited to 'contrib/llvm/tools/clang/lib/Sema/SemaChecking.cpp')
| -rw-r--r-- | contrib/llvm/tools/clang/lib/Sema/SemaChecking.cpp | 2404 |
1 files changed, 2404 insertions, 0 deletions
diff --git a/contrib/llvm/tools/clang/lib/Sema/SemaChecking.cpp b/contrib/llvm/tools/clang/lib/Sema/SemaChecking.cpp new file mode 100644 index 0000000..4f3f41b --- /dev/null +++ b/contrib/llvm/tools/clang/lib/Sema/SemaChecking.cpp @@ -0,0 +1,2404 @@ +//===--- SemaChecking.cpp - Extra Semantic Checking -----------------------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This file implements extra semantic analysis beyond what is enforced +// by the C type system. +// +//===----------------------------------------------------------------------===// + +#include "Sema.h" +#include "clang/Analysis/Analyses/PrintfFormatString.h" +#include "clang/AST/ASTContext.h" +#include "clang/AST/CharUnits.h" +#include "clang/AST/DeclObjC.h" +#include "clang/AST/ExprCXX.h" +#include "clang/AST/ExprObjC.h" +#include "clang/AST/DeclObjC.h" +#include "clang/AST/StmtCXX.h" +#include "clang/AST/StmtObjC.h" +#include "clang/Lex/LiteralSupport.h" +#include "clang/Lex/Preprocessor.h" +#include "llvm/ADT/BitVector.h" +#include "llvm/ADT/STLExtras.h" +#include "clang/Basic/TargetBuiltins.h" +#include <limits> +using namespace clang; + +/// getLocationOfStringLiteralByte - Return a source location that points to the +/// specified byte of the specified string literal. +/// +/// Strings are amazingly complex. They can be formed from multiple tokens and +/// can have escape sequences in them in addition to the usual trigraph and +/// escaped newline business. This routine handles this complexity. +/// +SourceLocation Sema::getLocationOfStringLiteralByte(const StringLiteral *SL, + unsigned ByteNo) const { + assert(!SL->isWide() && "This doesn't work for wide strings yet"); + + // Loop over all of the tokens in this string until we find the one that + // contains the byte we're looking for. + unsigned TokNo = 0; + while (1) { + assert(TokNo < SL->getNumConcatenated() && "Invalid byte number!"); + SourceLocation StrTokLoc = SL->getStrTokenLoc(TokNo); + + // Get the spelling of the string so that we can get the data that makes up + // the string literal, not the identifier for the macro it is potentially + // expanded through. + SourceLocation StrTokSpellingLoc = SourceMgr.getSpellingLoc(StrTokLoc); + + // Re-lex the token to get its length and original spelling. + std::pair<FileID, unsigned> LocInfo = + SourceMgr.getDecomposedLoc(StrTokSpellingLoc); + bool Invalid = false; + llvm::StringRef Buffer = SourceMgr.getBufferData(LocInfo.first, &Invalid); + if (Invalid) + return StrTokSpellingLoc; + + const char *StrData = Buffer.data()+LocInfo.second; + + // Create a langops struct and enable trigraphs. This is sufficient for + // relexing tokens. + LangOptions LangOpts; + LangOpts.Trigraphs = true; + + // Create a lexer starting at the beginning of this token. + Lexer TheLexer(StrTokSpellingLoc, LangOpts, Buffer.begin(), StrData, + Buffer.end()); + Token TheTok; + TheLexer.LexFromRawLexer(TheTok); + + // Use the StringLiteralParser to compute the length of the string in bytes. + StringLiteralParser SLP(&TheTok, 1, PP, /*Complain=*/false); + unsigned TokNumBytes = SLP.GetStringLength(); + + // If the byte is in this token, return the location of the byte. + if (ByteNo < TokNumBytes || + (ByteNo == TokNumBytes && TokNo == SL->getNumConcatenated())) { + unsigned Offset = + StringLiteralParser::getOffsetOfStringByte(TheTok, ByteNo, PP, + /*Complain=*/false); + + // Now that we know the offset of the token in the spelling, use the + // preprocessor to get the offset in the original source. + return PP.AdvanceToTokenCharacter(StrTokLoc, Offset); + } + + // Move to the next string token. + ++TokNo; + ByteNo -= TokNumBytes; + } +} + +/// CheckablePrintfAttr - does a function call have a "printf" attribute +/// and arguments that merit checking? +bool Sema::CheckablePrintfAttr(const FormatAttr *Format, CallExpr *TheCall) { + if (Format->getType() == "printf") return true; + if (Format->getType() == "printf0") { + // printf0 allows null "format" string; if so don't check format/args + unsigned format_idx = Format->getFormatIdx() - 1; + // Does the index refer to the implicit object argument? + if (isa<CXXMemberCallExpr>(TheCall)) { + if (format_idx == 0) + return false; + --format_idx; + } + if (format_idx < TheCall->getNumArgs()) { + Expr *Format = TheCall->getArg(format_idx)->IgnoreParenCasts(); + if (!Format->isNullPointerConstant(Context, + Expr::NPC_ValueDependentIsNull)) + return true; + } + } + return false; +} + +Action::OwningExprResult +Sema::CheckBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) { + OwningExprResult TheCallResult(Owned(TheCall)); + + switch (BuiltinID) { + case Builtin::BI__builtin___CFStringMakeConstantString: + assert(TheCall->getNumArgs() == 1 && + "Wrong # arguments to builtin CFStringMakeConstantString"); + if (CheckObjCString(TheCall->getArg(0))) + return ExprError(); + break; + case Builtin::BI__builtin_stdarg_start: + case Builtin::BI__builtin_va_start: + if (SemaBuiltinVAStart(TheCall)) + return ExprError(); + break; + case Builtin::BI__builtin_isgreater: + case Builtin::BI__builtin_isgreaterequal: + case Builtin::BI__builtin_isless: + case Builtin::BI__builtin_islessequal: + case Builtin::BI__builtin_islessgreater: + case Builtin::BI__builtin_isunordered: + if (SemaBuiltinUnorderedCompare(TheCall)) + return ExprError(); + break; + case Builtin::BI__builtin_fpclassify: + if (SemaBuiltinFPClassification(TheCall, 6)) + return ExprError(); + break; + case Builtin::BI__builtin_isfinite: + case Builtin::BI__builtin_isinf: + case Builtin::BI__builtin_isinf_sign: + case Builtin::BI__builtin_isnan: + case Builtin::BI__builtin_isnormal: + if (SemaBuiltinFPClassification(TheCall, 1)) + return ExprError(); + break; + case Builtin::BI__builtin_return_address: + case Builtin::BI__builtin_frame_address: { + llvm::APSInt Result; + if (SemaBuiltinConstantArg(TheCall, 0, Result)) + return ExprError(); + break; + } + case Builtin::BI__builtin_eh_return_data_regno: { + llvm::APSInt Result; + if (SemaBuiltinConstantArg(TheCall, 0, Result)) + return ExprError(); + break; + } + case Builtin::BI__builtin_shufflevector: + return SemaBuiltinShuffleVector(TheCall); + // TheCall will be freed by the smart pointer here, but that's fine, since + // SemaBuiltinShuffleVector guts it, but then doesn't release it. + case Builtin::BI__builtin_prefetch: + if (SemaBuiltinPrefetch(TheCall)) + return ExprError(); + break; + case Builtin::BI__builtin_object_size: + if (SemaBuiltinObjectSize(TheCall)) + return ExprError(); + break; + case Builtin::BI__builtin_longjmp: + if (SemaBuiltinLongjmp(TheCall)) + return ExprError(); + break; + case Builtin::BI__sync_fetch_and_add: + case Builtin::BI__sync_fetch_and_sub: + case Builtin::BI__sync_fetch_and_or: + case Builtin::BI__sync_fetch_and_and: + case Builtin::BI__sync_fetch_and_xor: + case Builtin::BI__sync_add_and_fetch: + case Builtin::BI__sync_sub_and_fetch: + case Builtin::BI__sync_and_and_fetch: + case Builtin::BI__sync_or_and_fetch: + case Builtin::BI__sync_xor_and_fetch: + case Builtin::BI__sync_val_compare_and_swap: + case Builtin::BI__sync_bool_compare_and_swap: + case Builtin::BI__sync_lock_test_and_set: + case Builtin::BI__sync_lock_release: + if (SemaBuiltinAtomicOverloaded(TheCall)) + return ExprError(); + break; + + // Target specific builtins start here. + case X86::BI__builtin_ia32_palignr128: + case X86::BI__builtin_ia32_palignr: { + llvm::APSInt Result; + if (SemaBuiltinConstantArg(TheCall, 2, Result)) + return ExprError(); + break; + } + } + + return move(TheCallResult); +} + +/// CheckFunctionCall - Check a direct function call for various correctness +/// and safety properties not strictly enforced by the C type system. +bool Sema::CheckFunctionCall(FunctionDecl *FDecl, CallExpr *TheCall) { + // Get the IdentifierInfo* for the called function. + IdentifierInfo *FnInfo = FDecl->getIdentifier(); + + // None of the checks below are needed for functions that don't have + // simple names (e.g., C++ conversion functions). + if (!FnInfo) + return false; + + // FIXME: This mechanism should be abstracted to be less fragile and + // more efficient. For example, just map function ids to custom + // handlers. + + // Printf checking. + if (const FormatAttr *Format = FDecl->getAttr<FormatAttr>()) { + if (CheckablePrintfAttr(Format, TheCall)) { + bool HasVAListArg = Format->getFirstArg() == 0; + CheckPrintfArguments(TheCall, HasVAListArg, Format->getFormatIdx() - 1, + HasVAListArg ? 0 : Format->getFirstArg() - 1); + } + } + + for (const NonNullAttr *NonNull = FDecl->getAttr<NonNullAttr>(); NonNull; + NonNull = NonNull->getNext<NonNullAttr>()) + CheckNonNullArguments(NonNull, TheCall); + + return false; +} + +bool Sema::CheckBlockCall(NamedDecl *NDecl, CallExpr *TheCall) { + // Printf checking. + const FormatAttr *Format = NDecl->getAttr<FormatAttr>(); + if (!Format) + return false; + + const VarDecl *V = dyn_cast<VarDecl>(NDecl); + if (!V) + return false; + + QualType Ty = V->getType(); + if (!Ty->isBlockPointerType()) + return false; + + if (!CheckablePrintfAttr(Format, TheCall)) + return false; + + bool HasVAListArg = Format->getFirstArg() == 0; + CheckPrintfArguments(TheCall, HasVAListArg, Format->getFormatIdx() - 1, + HasVAListArg ? 0 : Format->getFirstArg() - 1); + + return false; +} + +/// SemaBuiltinAtomicOverloaded - We have a call to a function like +/// __sync_fetch_and_add, which is an overloaded function based on the pointer +/// type of its first argument. The main ActOnCallExpr routines have already +/// promoted the types of arguments because all of these calls are prototyped as +/// void(...). +/// +/// This function goes through and does final semantic checking for these +/// builtins, +bool Sema::SemaBuiltinAtomicOverloaded(CallExpr *TheCall) { + DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts()); + FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl()); + + // Ensure that we have at least one argument to do type inference from. + if (TheCall->getNumArgs() < 1) + return Diag(TheCall->getLocEnd(), + diag::err_typecheck_call_too_few_args_at_least) + << 0 << 1 << TheCall->getNumArgs() + << TheCall->getCallee()->getSourceRange(); + + // Inspect the first argument of the atomic builtin. This should always be + // a pointer type, whose element is an integral scalar or pointer type. + // Because it is a pointer type, we don't have to worry about any implicit + // casts here. + Expr *FirstArg = TheCall->getArg(0); + if (!FirstArg->getType()->isPointerType()) + return Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer) + << FirstArg->getType() << FirstArg->getSourceRange(); + + QualType ValType = FirstArg->getType()->getAs<PointerType>()->getPointeeType(); + if (!ValType->isIntegerType() && !ValType->isPointerType() && + !ValType->isBlockPointerType()) + return Diag(DRE->getLocStart(), + diag::err_atomic_builtin_must_be_pointer_intptr) + << FirstArg->getType() << FirstArg->getSourceRange(); + + // We need to figure out which concrete builtin this maps onto. For example, + // __sync_fetch_and_add with a 2 byte object turns into + // __sync_fetch_and_add_2. +#define BUILTIN_ROW(x) \ + { Builtin::BI##x##_1, Builtin::BI##x##_2, Builtin::BI##x##_4, \ + Builtin::BI##x##_8, Builtin::BI##x##_16 } + + static const unsigned BuiltinIndices[][5] = { + BUILTIN_ROW(__sync_fetch_and_add), + BUILTIN_ROW(__sync_fetch_and_sub), + BUILTIN_ROW(__sync_fetch_and_or), + BUILTIN_ROW(__sync_fetch_and_and), + BUILTIN_ROW(__sync_fetch_and_xor), + + BUILTIN_ROW(__sync_add_and_fetch), + BUILTIN_ROW(__sync_sub_and_fetch), + BUILTIN_ROW(__sync_and_and_fetch), + BUILTIN_ROW(__sync_or_and_fetch), + BUILTIN_ROW(__sync_xor_and_fetch), + + BUILTIN_ROW(__sync_val_compare_and_swap), + BUILTIN_ROW(__sync_bool_compare_and_swap), + BUILTIN_ROW(__sync_lock_test_and_set), + BUILTIN_ROW(__sync_lock_release) + }; +#undef BUILTIN_ROW + + // Determine the index of the size. + unsigned SizeIndex; + switch (Context.getTypeSizeInChars(ValType).getQuantity()) { + case 1: SizeIndex = 0; break; + case 2: SizeIndex = 1; break; + case 4: SizeIndex = 2; break; + case 8: SizeIndex = 3; break; + case 16: SizeIndex = 4; break; + default: + return Diag(DRE->getLocStart(), diag::err_atomic_builtin_pointer_size) + << FirstArg->getType() << FirstArg->getSourceRange(); + } + + // Each of these builtins has one pointer argument, followed by some number of + // values (0, 1 or 2) followed by a potentially empty varags list of stuff + // that we ignore. Find out which row of BuiltinIndices to read from as well + // as the number of fixed args. + unsigned BuiltinID = FDecl->getBuiltinID(); + unsigned BuiltinIndex, NumFixed = 1; + switch (BuiltinID) { + default: assert(0 && "Unknown overloaded atomic builtin!"); + case Builtin::BI__sync_fetch_and_add: BuiltinIndex = 0; break; + case Builtin::BI__sync_fetch_and_sub: BuiltinIndex = 1; break; + case Builtin::BI__sync_fetch_and_or: BuiltinIndex = 2; break; + case Builtin::BI__sync_fetch_and_and: BuiltinIndex = 3; break; + case Builtin::BI__sync_fetch_and_xor: BuiltinIndex = 4; break; + + case Builtin::BI__sync_add_and_fetch: BuiltinIndex = 5; break; + case Builtin::BI__sync_sub_and_fetch: BuiltinIndex = 6; break; + case Builtin::BI__sync_and_and_fetch: BuiltinIndex = 7; break; + case Builtin::BI__sync_or_and_fetch: BuiltinIndex = 8; break; + case Builtin::BI__sync_xor_and_fetch: BuiltinIndex = 9; break; + + case Builtin::BI__sync_val_compare_and_swap: + BuiltinIndex = 10; + NumFixed = 2; + break; + case Builtin::BI__sync_bool_compare_and_swap: + BuiltinIndex = 11; + NumFixed = 2; + break; + case Builtin::BI__sync_lock_test_and_set: BuiltinIndex = 12; break; + case Builtin::BI__sync_lock_release: + BuiltinIndex = 13; + NumFixed = 0; + break; + } + + // Now that we know how many fixed arguments we expect, first check that we + // have at least that many. + if (TheCall->getNumArgs() < 1+NumFixed) + return Diag(TheCall->getLocEnd(), + diag::err_typecheck_call_too_few_args_at_least) + << 0 << 1+NumFixed << TheCall->getNumArgs() + << TheCall->getCallee()->getSourceRange(); + + + // Get the decl for the concrete builtin from this, we can tell what the + // concrete integer type we should convert to is. + unsigned NewBuiltinID = BuiltinIndices[BuiltinIndex][SizeIndex]; + const char *NewBuiltinName = Context.BuiltinInfo.GetName(NewBuiltinID); + IdentifierInfo *NewBuiltinII = PP.getIdentifierInfo(NewBuiltinName); + FunctionDecl *NewBuiltinDecl = + cast<FunctionDecl>(LazilyCreateBuiltin(NewBuiltinII, NewBuiltinID, + TUScope, false, DRE->getLocStart())); + const FunctionProtoType *BuiltinFT = + NewBuiltinDecl->getType()->getAs<FunctionProtoType>(); + ValType = BuiltinFT->getArgType(0)->getAs<PointerType>()->getPointeeType(); + + // If the first type needs to be converted (e.g. void** -> int*), do it now. + if (BuiltinFT->getArgType(0) != FirstArg->getType()) { + ImpCastExprToType(FirstArg, BuiltinFT->getArgType(0), CastExpr::CK_BitCast); + TheCall->setArg(0, FirstArg); + } + + // Next, walk the valid ones promoting to the right type. + for (unsigned i = 0; i != NumFixed; ++i) { + Expr *Arg = TheCall->getArg(i+1); + + // If the argument is an implicit cast, then there was a promotion due to + // "...", just remove it now. + if (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Arg)) { + Arg = ICE->getSubExpr(); + ICE->setSubExpr(0); + ICE->Destroy(Context); + TheCall->setArg(i+1, Arg); + } + + // GCC does an implicit conversion to the pointer or integer ValType. This + // can fail in some cases (1i -> int**), check for this error case now. + CastExpr::CastKind Kind = CastExpr::CK_Unknown; + CXXBaseSpecifierArray BasePath; + if (CheckCastTypes(Arg->getSourceRange(), ValType, Arg, Kind, BasePath)) + return true; + + // Okay, we have something that *can* be converted to the right type. Check + // to see if there is a potentially weird extension going on here. This can + // happen when you do an atomic operation on something like an char* and + // pass in 42. The 42 gets converted to char. This is even more strange + // for things like 45.123 -> char, etc. + // FIXME: Do this check. + ImpCastExprToType(Arg, ValType, Kind); + TheCall->setArg(i+1, Arg); + } + + // Switch the DeclRefExpr to refer to the new decl. + DRE->setDecl(NewBuiltinDecl); + DRE->setType(NewBuiltinDecl->getType()); + + // Set the callee in the CallExpr. + // FIXME: This leaks the original parens and implicit casts. + Expr *PromotedCall = DRE; + UsualUnaryConversions(PromotedCall); + TheCall->setCallee(PromotedCall); + + + // Change the result type of the call to match the result type of the decl. + TheCall->setType(NewBuiltinDecl->getResultType()); + return false; +} + + +/// CheckObjCString - Checks that the argument to the builtin +/// CFString constructor is correct +/// FIXME: GCC currently emits the following warning: +/// "warning: input conversion stopped due to an input byte that does not +/// belong to the input codeset UTF-8" +/// Note: It might also make sense to do the UTF-16 conversion here (would +/// simplify the backend). +bool Sema::CheckObjCString(Expr *Arg) { + Arg = Arg->IgnoreParenCasts(); + StringLiteral *Literal = dyn_cast<StringLiteral>(Arg); + + if (!Literal || Literal->isWide()) { + Diag(Arg->getLocStart(), diag::err_cfstring_literal_not_string_constant) + << Arg->getSourceRange(); + return true; + } + + const char *Data = Literal->getStrData(); + unsigned Length = Literal->getByteLength(); + + for (unsigned i = 0; i < Length; ++i) { + if (!Data[i]) { + Diag(getLocationOfStringLiteralByte(Literal, i), + diag::warn_cfstring_literal_contains_nul_character) + << Arg->getSourceRange(); + break; + } + } + + return false; +} + +/// SemaBuiltinVAStart - Check the arguments to __builtin_va_start for validity. +/// Emit an error and return true on failure, return false on success. +bool Sema::SemaBuiltinVAStart(CallExpr *TheCall) { + Expr *Fn = TheCall->getCallee(); + if (TheCall->getNumArgs() > 2) { + Diag(TheCall->getArg(2)->getLocStart(), + diag::err_typecheck_call_too_many_args) + << 0 /*function call*/ << 2 << TheCall->getNumArgs() + << Fn->getSourceRange() + << SourceRange(TheCall->getArg(2)->getLocStart(), + (*(TheCall->arg_end()-1))->getLocEnd()); + return true; + } + + if (TheCall->getNumArgs() < 2) { + return Diag(TheCall->getLocEnd(), + diag::err_typecheck_call_too_few_args_at_least) + << 0 /*function call*/ << 2 << TheCall->getNumArgs(); + } + + // Determine whether the current function is variadic or not. + BlockScopeInfo *CurBlock = getCurBlock(); + bool isVariadic; + if (CurBlock) + isVariadic = CurBlock->isVariadic; + else if (FunctionDecl *FD = getCurFunctionDecl()) + isVariadic = FD->isVariadic(); + else + isVariadic = getCurMethodDecl()->isVariadic(); + + if (!isVariadic) { + Diag(Fn->getLocStart(), diag::err_va_start_used_in_non_variadic_function); + return true; + } + + // Verify that the second argument to the builtin is the last argument of the + // current function or method. + bool SecondArgIsLastNamedArgument = false; + const Expr *Arg = TheCall->getArg(1)->IgnoreParenCasts(); + + if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Arg)) { + if (const ParmVarDecl *PV = dyn_cast<ParmVarDecl>(DR->getDecl())) { + // FIXME: This isn't correct for methods (results in bogus warning). + // Get the last formal in the current function. + const ParmVarDecl *LastArg; + if (CurBlock) + LastArg = *(CurBlock->TheDecl->param_end()-1); + else if (FunctionDecl *FD = getCurFunctionDecl()) + LastArg = *(FD->param_end()-1); + else + LastArg = *(getCurMethodDecl()->param_end()-1); + SecondArgIsLastNamedArgument = PV == LastArg; + } + } + + if (!SecondArgIsLastNamedArgument) + Diag(TheCall->getArg(1)->getLocStart(), + diag::warn_second_parameter_of_va_start_not_last_named_argument); + return false; +} + +/// SemaBuiltinUnorderedCompare - Handle functions like __builtin_isgreater and +/// friends. This is declared to take (...), so we have to check everything. +bool Sema::SemaBuiltinUnorderedCompare(CallExpr *TheCall) { + if (TheCall->getNumArgs() < 2) + return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args) + << 0 << 2 << TheCall->getNumArgs()/*function call*/; + if (TheCall->getNumArgs() > 2) + return Diag(TheCall->getArg(2)->getLocStart(), + diag::err_typecheck_call_too_many_args) + << 0 /*function call*/ << 2 << TheCall->getNumArgs() + << SourceRange(TheCall->getArg(2)->getLocStart(), + (*(TheCall->arg_end()-1))->getLocEnd()); + + Expr *OrigArg0 = TheCall->getArg(0); + Expr *OrigArg1 = TheCall->getArg(1); + + // Do standard promotions between the two arguments, returning their common + // type. + QualType Res = UsualArithmeticConversions(OrigArg0, OrigArg1, false); + + // Make sure any conversions are pushed back into the call; this is + // type safe since unordered compare builtins are declared as "_Bool + // foo(...)". + TheCall->setArg(0, OrigArg0); + TheCall->setArg(1, OrigArg1); + + if (OrigArg0->isTypeDependent() || OrigArg1->isTypeDependent()) + return false; + + // If the common type isn't a real floating type, then the arguments were + // invalid for this operation. + if (!Res->isRealFloatingType()) + return Diag(OrigArg0->getLocStart(), + diag::err_typecheck_call_invalid_ordered_compare) + << OrigArg0->getType() << OrigArg1->getType() + << SourceRange(OrigArg0->getLocStart(), OrigArg1->getLocEnd()); + + return false; +} + +/// SemaBuiltinSemaBuiltinFPClassification - Handle functions like +/// __builtin_isnan and friends. This is declared to take (...), so we have +/// to check everything. We expect the last argument to be a floating point +/// value. +bool Sema::SemaBuiltinFPClassification(CallExpr *TheCall, unsigned NumArgs) { + if (TheCall->getNumArgs() < NumArgs) + return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args) + << 0 << NumArgs << TheCall->getNumArgs()/*function call*/; + if (TheCall->getNumArgs() > NumArgs) + return Diag(TheCall->getArg(NumArgs)->getLocStart(), + diag::err_typecheck_call_too_many_args) + << 0 /*function call*/ << NumArgs << TheCall->getNumArgs() + << SourceRange(TheCall->getArg(NumArgs)->getLocStart(), + (*(TheCall->arg_end()-1))->getLocEnd()); + + Expr *OrigArg = TheCall->getArg(NumArgs-1); + + if (OrigArg->isTypeDependent()) + return false; + + // This operation requires a non-_Complex floating-point number. + if (!OrigArg->getType()->isRealFloatingType()) + return Diag(OrigArg->getLocStart(), + diag::err_typecheck_call_invalid_unary_fp) + << OrigArg->getType() << OrigArg->getSourceRange(); + + // If this is an implicit conversion from float -> double, remove it. + if (ImplicitCastExpr *Cast = dyn_cast<ImplicitCastExpr>(OrigArg)) { + Expr *CastArg = Cast->getSubExpr(); + if (CastArg->getType()->isSpecificBuiltinType(BuiltinType::Float)) { + assert(Cast->getType()->isSpecificBuiltinType(BuiltinType::Double) && + "promotion from float to double is the only expected cast here"); + Cast->setSubExpr(0); + Cast->Destroy(Context); + TheCall->setArg(NumArgs-1, CastArg); + OrigArg = CastArg; + } + } + + return false; +} + +/// SemaBuiltinShuffleVector - Handle __builtin_shufflevector. +// This is declared to take (...), so we have to check everything. +Action::OwningExprResult Sema::SemaBuiltinShuffleVector(CallExpr *TheCall) { + if (TheCall->getNumArgs() < 3) + return ExprError(Diag(TheCall->getLocEnd(), + diag::err_typecheck_call_too_few_args_at_least) + << 0 /*function call*/ << 3 << TheCall->getNumArgs() + << TheCall->getSourceRange()); + + unsigned numElements = std::numeric_limits<unsigned>::max(); + if (!TheCall->getArg(0)->isTypeDependent() && + !TheCall->getArg(1)->isTypeDependent()) { + QualType FAType = TheCall->getArg(0)->getType(); + QualType SAType = TheCall->getArg(1)->getType(); + + if (!FAType->isVectorType() || !SAType->isVectorType()) { + Diag(TheCall->getLocStart(), diag::err_shufflevector_non_vector) + << SourceRange(TheCall->getArg(0)->getLocStart(), + TheCall->getArg(1)->getLocEnd()); + return ExprError(); + } + + if (!Context.hasSameUnqualifiedType(FAType, SAType)) { + Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector) + << SourceRange(TheCall->getArg(0)->getLocStart(), + TheCall->getArg(1)->getLocEnd()); + return ExprError(); + } + + numElements = FAType->getAs<VectorType>()->getNumElements(); + if (TheCall->getNumArgs() != numElements+2) { + if (TheCall->getNumArgs() < numElements+2) + return ExprError(Diag(TheCall->getLocEnd(), + diag::err_typecheck_call_too_few_args) + << 0 /*function call*/ + << numElements+2 << TheCall->getNumArgs() + << TheCall->getSourceRange()); + return ExprError(Diag(TheCall->getLocEnd(), + diag::err_typecheck_call_too_many_args) + << 0 /*function call*/ + << numElements+2 << TheCall->getNumArgs() + << TheCall->getSourceRange()); + } + } + + for (unsigned i = 2; i < TheCall->getNumArgs(); i++) { + if (TheCall->getArg(i)->isTypeDependent() || + TheCall->getArg(i)->isValueDependent()) + continue; + + llvm::APSInt Result; + if (SemaBuiltinConstantArg(TheCall, i, Result)) + return ExprError(); + + if (Result.getActiveBits() > 64 || Result.getZExtValue() >= numElements*2) + return ExprError(Diag(TheCall->getLocStart(), + diag::err_shufflevector_argument_too_large) + << TheCall->getArg(i)->getSourceRange()); + } + + llvm::SmallVector<Expr*, 32> exprs; + + for (unsigned i = 0, e = TheCall->getNumArgs(); i != e; i++) { + exprs.push_back(TheCall->getArg(i)); + TheCall->setArg(i, 0); + } + + return Owned(new (Context) ShuffleVectorExpr(Context, exprs.begin(), + exprs.size(), exprs[0]->getType(), + TheCall->getCallee()->getLocStart(), + TheCall->getRParenLoc())); +} + +/// SemaBuiltinPrefetch - Handle __builtin_prefetch. +// This is declared to take (const void*, ...) and can take two +// optional constant int args. +bool Sema::SemaBuiltinPrefetch(CallExpr *TheCall) { + unsigned NumArgs = TheCall->getNumArgs(); + + if (NumArgs > 3) + return Diag(TheCall->getLocEnd(), + diag::err_typecheck_call_too_many_args_at_most) + << 0 /*function call*/ << 3 << NumArgs + << TheCall->getSourceRange(); + + // Argument 0 is checked for us and the remaining arguments must be + // constant integers. + for (unsigned i = 1; i != NumArgs; ++i) { + Expr *Arg = TheCall->getArg(i); + + llvm::APSInt Result; + if (SemaBuiltinConstantArg(TheCall, i, Result)) + return true; + + // FIXME: gcc issues a warning and rewrites these to 0. These + // seems especially odd for the third argument since the default + // is 3. + if (i == 1) { + if (Result.getLimitedValue() > 1) + return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) + << "0" << "1" << Arg->getSourceRange(); + } else { + if (Result.getLimitedValue() > 3) + return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) + << "0" << "3" << Arg->getSourceRange(); + } + } + + return false; +} + +/// SemaBuiltinConstantArg - Handle a check if argument ArgNum of CallExpr +/// TheCall is a constant expression. +bool Sema::SemaBuiltinConstantArg(CallExpr *TheCall, int ArgNum, + llvm::APSInt &Result) { + Expr *Arg = TheCall->getArg(ArgNum); + DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts()); + FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl()); + + if (Arg->isTypeDependent() || Arg->isValueDependent()) return false; + + if (!Arg->isIntegerConstantExpr(Result, Context)) + return Diag(TheCall->getLocStart(), diag::err_constant_integer_arg_type) + << FDecl->getDeclName() << Arg->getSourceRange(); + + return false; +} + +/// SemaBuiltinObjectSize - Handle __builtin_object_size(void *ptr, +/// int type). This simply type checks that type is one of the defined +/// constants (0-3). +// For compatability check 0-3, llvm only handles 0 and 2. +bool Sema::SemaBuiltinObjectSize(CallExpr *TheCall) { + llvm::APSInt Result; + + // Check constant-ness first. + if (SemaBuiltinConstantArg(TheCall, 1, Result)) + return true; + + Expr *Arg = TheCall->getArg(1); + if (Result.getSExtValue() < 0 || Result.getSExtValue() > 3) { + return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) + << "0" << "3" << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); + } + + return false; +} + +/// SemaBuiltinLongjmp - Handle __builtin_longjmp(void *env[5], int val). +/// This checks that val is a constant 1. +bool Sema::SemaBuiltinLongjmp(CallExpr *TheCall) { + Expr *Arg = TheCall->getArg(1); + llvm::APSInt Result; + + // TODO: This is less than ideal. Overload this to take a value. + if (SemaBuiltinConstantArg(TheCall, 1, Result)) + return true; + + if (Result != 1) + return Diag(TheCall->getLocStart(), diag::err_builtin_longjmp_invalid_val) + << SourceRange(Arg->getLocStart(), Arg->getLocEnd()); + + return false; +} + +// Handle i > 1 ? "x" : "y", recursivelly +bool Sema::SemaCheckStringLiteral(const Expr *E, const CallExpr *TheCall, + bool HasVAListArg, + unsigned format_idx, unsigned firstDataArg) { + if (E->isTypeDependent() || E->isValueDependent()) + return false; + + switch (E->getStmtClass()) { + case Stmt::ConditionalOperatorClass: { + const ConditionalOperator *C = cast<ConditionalOperator>(E); + return SemaCheckStringLiteral(C->getTrueExpr(), TheCall, + HasVAListArg, format_idx, firstDataArg) + && SemaCheckStringLiteral(C->getRHS(), TheCall, + HasVAListArg, format_idx, firstDataArg); + } + + case Stmt::ImplicitCastExprClass: { + const ImplicitCastExpr *Expr = cast<ImplicitCastExpr>(E); + return SemaCheckStringLiteral(Expr->getSubExpr(), TheCall, HasVAListArg, + format_idx, firstDataArg); + } + + case Stmt::ParenExprClass: { + const ParenExpr *Expr = cast<ParenExpr>(E); + return SemaCheckStringLiteral(Expr->getSubExpr(), TheCall, HasVAListArg, + format_idx, firstDataArg); + } + + case Stmt::DeclRefExprClass: { + const DeclRefExpr *DR = cast<DeclRefExpr>(E); + + // As an exception, do not flag errors for variables binding to + // const string literals. + if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) { + bool isConstant = false; + QualType T = DR->getType(); + + if (const ArrayType *AT = Context.getAsArrayType(T)) { + isConstant = AT->getElementType().isConstant(Context); + } else if (const PointerType *PT = T->getAs<PointerType>()) { + isConstant = T.isConstant(Context) && + PT->getPointeeType().isConstant(Context); + } + + if (isConstant) { + if (const Expr *Init = VD->getAnyInitializer()) + return SemaCheckStringLiteral(Init, TheCall, + HasVAListArg, format_idx, firstDataArg); + } + + // For vprintf* functions (i.e., HasVAListArg==true), we add a + // special check to see if the format string is a function parameter + // of the function calling the printf function. If the function + // has an attribute indicating it is a printf-like function, then we + // should suppress warnings concerning non-literals being used in a call + // to a vprintf function. For example: + // + // void + // logmessage(char const *fmt __attribute__ (format (printf, 1, 2)), ...){ + // va_list ap; + // va_start(ap, fmt); + // vprintf(fmt, ap); // Do NOT emit a warning about "fmt". + // ... + // + // + // FIXME: We don't have full attribute support yet, so just check to see + // if the argument is a DeclRefExpr that references a parameter. We'll + // add proper support for checking the attribute later. + if (HasVAListArg) + if (isa<ParmVarDecl>(VD)) + return true; + } + + return false; + } + + case Stmt::CallExprClass: { + const CallExpr *CE = cast<CallExpr>(E); + if (const ImplicitCastExpr *ICE + = dyn_cast<ImplicitCastExpr>(CE->getCallee())) { + if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(ICE->getSubExpr())) { + if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(DRE->getDecl())) { + if (const FormatArgAttr *FA = FD->getAttr<FormatArgAttr>()) { + unsigned ArgIndex = FA->getFormatIdx(); + const Expr *Arg = CE->getArg(ArgIndex - 1); + + return SemaCheckStringLiteral(Arg, TheCall, HasVAListArg, + format_idx, firstDataArg); + } + } + } + } + + return false; + } + case Stmt::ObjCStringLiteralClass: + case Stmt::StringLiteralClass: { + const StringLiteral *StrE = NULL; + + if (const ObjCStringLiteral *ObjCFExpr = dyn_cast<ObjCStringLiteral>(E)) + StrE = ObjCFExpr->getString(); + else + StrE = cast<StringLiteral>(E); + + if (StrE) { + CheckPrintfString(StrE, E, TheCall, HasVAListArg, format_idx, + firstDataArg); + return true; + } + + return false; + } + + default: + return false; + } +} + +void +Sema::CheckNonNullArguments(const NonNullAttr *NonNull, + const CallExpr *TheCall) { + for (NonNullAttr::iterator i = NonNull->begin(), e = NonNull->end(); + i != e; ++i) { + const Expr *ArgExpr = TheCall->getArg(*i); + if (ArgExpr->isNullPointerConstant(Context, + Expr::NPC_ValueDependentIsNotNull)) + Diag(TheCall->getCallee()->getLocStart(), diag::warn_null_arg) + << ArgExpr->getSourceRange(); + } +} + +/// CheckPrintfArguments - Check calls to printf (and similar functions) for +/// correct use of format strings. +/// +/// HasVAListArg - A predicate indicating whether the printf-like +/// function is passed an explicit va_arg argument (e.g., vprintf) +/// +/// format_idx - The index into Args for the format string. +/// +/// Improper format strings to functions in the printf family can be +/// the source of bizarre bugs and very serious security holes. A +/// good source of information is available in the following paper +/// (which includes additional references): +/// +/// FormatGuard: Automatic Protection From printf Format String +/// Vulnerabilities, Proceedings of the 10th USENIX Security Symposium, 2001. +/// +/// TODO: +/// Functionality implemented: +/// +/// We can statically check the following properties for string +/// literal format strings for non v.*printf functions (where the +/// arguments are passed directly): +// +/// (1) Are the number of format conversions equal to the number of +/// data arguments? +/// +/// (2) Does each format conversion correctly match the type of the +/// corresponding data argument? +/// +/// Moreover, for all printf functions we can: +/// +/// (3) Check for a missing format string (when not caught by type checking). +/// +/// (4) Check for no-operation flags; e.g. using "#" with format +/// conversion 'c' (TODO) +/// +/// (5) Check the use of '%n', a major source of security holes. +/// +/// (6) Check for malformed format conversions that don't specify anything. +/// +/// (7) Check for empty format strings. e.g: printf(""); +/// +/// (8) Check that the format string is a wide literal. +/// +/// All of these checks can be done by parsing the format string. +/// +void +Sema::CheckPrintfArguments(const CallExpr *TheCall, bool HasVAListArg, + unsigned format_idx, unsigned firstDataArg) { + const Expr *Fn = TheCall->getCallee(); + + // The way the format attribute works in GCC, the implicit this argument + // of member functions is counted. However, it doesn't appear in our own + // lists, so decrement format_idx in that case. + if (isa<CXXMemberCallExpr>(TheCall)) { + // Catch a format attribute mistakenly referring to the object argument. + if (format_idx == 0) + return; + --format_idx; + if(firstDataArg != 0) + --firstDataArg; + } + + // CHECK: printf-like function is called with no format string. + if (format_idx >= TheCall->getNumArgs()) { + Diag(TheCall->getRParenLoc(), diag::warn_printf_missing_format_string) + << Fn->getSourceRange(); + return; + } + + const Expr *OrigFormatExpr = TheCall->getArg(format_idx)->IgnoreParenCasts(); + + // CHECK: format string is not a string literal. + // + // Dynamically generated format strings are difficult to + // automatically vet at compile time. Requiring that format strings + // are string literals: (1) permits the checking of format strings by + // the compiler and thereby (2) can practically remove the source of + // many format string exploits. + + // Format string can be either ObjC string (e.g. @"%d") or + // C string (e.g. "%d") + // ObjC string uses the same format specifiers as C string, so we can use + // the same format string checking logic for both ObjC and C strings. + if (SemaCheckStringLiteral(OrigFormatExpr, TheCall, HasVAListArg, format_idx, + firstDataArg)) + return; // Literal format string found, check done! + + // If there are no arguments specified, warn with -Wformat-security, otherwise + // warn only with -Wformat-nonliteral. + if (TheCall->getNumArgs() == format_idx+1) + Diag(TheCall->getArg(format_idx)->getLocStart(), + diag::warn_printf_nonliteral_noargs) + << OrigFormatExpr->getSourceRange(); + else + Diag(TheCall->getArg(format_idx)->getLocStart(), + diag::warn_printf_nonliteral) + << OrigFormatExpr->getSourceRange(); +} + +namespace { +class CheckPrintfHandler : public analyze_printf::FormatStringHandler { + Sema &S; + const StringLiteral *FExpr; + const Expr *OrigFormatExpr; + const unsigned FirstDataArg; + const unsigned NumDataArgs; + const bool IsObjCLiteral; + const char *Beg; // Start of format string. + const bool HasVAListArg; + const CallExpr *TheCall; + unsigned FormatIdx; + llvm::BitVector CoveredArgs; + bool usesPositionalArgs; + bool atFirstArg; +public: + CheckPrintfHandler(Sema &s, const StringLiteral *fexpr, + const Expr *origFormatExpr, unsigned firstDataArg, + unsigned numDataArgs, bool isObjCLiteral, + const char *beg, bool hasVAListArg, + const CallExpr *theCall, unsigned formatIdx) + : S(s), FExpr(fexpr), OrigFormatExpr(origFormatExpr), + FirstDataArg(firstDataArg), + NumDataArgs(numDataArgs), + IsObjCLiteral(isObjCLiteral), Beg(beg), + HasVAListArg(hasVAListArg), + TheCall(theCall), FormatIdx(formatIdx), + usesPositionalArgs(false), atFirstArg(true) { + CoveredArgs.resize(numDataArgs); + CoveredArgs.reset(); + } + + void DoneProcessing(); + + void HandleIncompleteFormatSpecifier(const char *startSpecifier, + unsigned specifierLen); + + bool + HandleInvalidConversionSpecifier(const analyze_printf::FormatSpecifier &FS, + const char *startSpecifier, + unsigned specifierLen); + + virtual void HandleInvalidPosition(const char *startSpecifier, + unsigned specifierLen, + analyze_printf::PositionContext p); + + virtual void HandleZeroPosition(const char *startPos, unsigned posLen); + + void HandleNullChar(const char *nullCharacter); + + bool HandleFormatSpecifier(const analyze_printf::FormatSpecifier &FS, + const char *startSpecifier, + unsigned specifierLen); +private: + SourceRange getFormatStringRange(); + SourceRange getFormatSpecifierRange(const char *startSpecifier, + unsigned specifierLen); + SourceLocation getLocationOfByte(const char *x); + + bool HandleAmount(const analyze_printf::OptionalAmount &Amt, unsigned k, + const char *startSpecifier, unsigned specifierLen); + void HandleFlags(const analyze_printf::FormatSpecifier &FS, + llvm::StringRef flag, llvm::StringRef cspec, + const char *startSpecifier, unsigned specifierLen); + + const Expr *getDataArg(unsigned i) const; +}; +} + +SourceRange CheckPrintfHandler::getFormatStringRange() { + return OrigFormatExpr->getSourceRange(); +} + +SourceRange CheckPrintfHandler:: +getFormatSpecifierRange(const char *startSpecifier, unsigned specifierLen) { + return SourceRange(getLocationOfByte(startSpecifier), + getLocationOfByte(startSpecifier+specifierLen-1)); +} + +SourceLocation CheckPrintfHandler::getLocationOfByte(const char *x) { + return S.getLocationOfStringLiteralByte(FExpr, x - Beg); +} + +void CheckPrintfHandler:: +HandleIncompleteFormatSpecifier(const char *startSpecifier, + unsigned specifierLen) { + SourceLocation Loc = getLocationOfByte(startSpecifier); + S.Diag(Loc, diag::warn_printf_incomplete_specifier) + << getFormatSpecifierRange(startSpecifier, specifierLen); +} + +void +CheckPrintfHandler::HandleInvalidPosition(const char *startPos, unsigned posLen, + analyze_printf::PositionContext p) { + SourceLocation Loc = getLocationOfByte(startPos); + S.Diag(Loc, diag::warn_printf_invalid_positional_specifier) + << (unsigned) p << getFormatSpecifierRange(startPos, posLen); +} + +void CheckPrintfHandler::HandleZeroPosition(const char *startPos, + unsigned posLen) { + SourceLocation Loc = getLocationOfByte(startPos); + S.Diag(Loc, diag::warn_printf_zero_positional_specifier) + << getFormatSpecifierRange(startPos, posLen); +} + +bool CheckPrintfHandler:: +HandleInvalidConversionSpecifier(const analyze_printf::FormatSpecifier &FS, + const char *startSpecifier, + unsigned specifierLen) { + + unsigned argIndex = FS.getArgIndex(); + bool keepGoing = true; + if (argIndex < NumDataArgs) { + // Consider the argument coverered, even though the specifier doesn't + // make sense. + CoveredArgs.set(argIndex); + } + else { + // If argIndex exceeds the number of data arguments we + // don't issue a warning because that is just a cascade of warnings (and + // they may have intended '%%' anyway). We don't want to continue processing + // the format string after this point, however, as we will like just get + // gibberish when trying to match arguments. + keepGoing = false; + } + + const analyze_printf::ConversionSpecifier &CS = + FS.getConversionSpecifier(); + SourceLocation Loc = getLocationOfByte(CS.getStart()); + S.Diag(Loc, diag::warn_printf_invalid_conversion) + << llvm::StringRef(CS.getStart(), CS.getLength()) + << getFormatSpecifierRange(startSpecifier, specifierLen); + + return keepGoing; +} + +void CheckPrintfHandler::HandleNullChar(const char *nullCharacter) { + // The presence of a null character is likely an error. + S.Diag(getLocationOfByte(nullCharacter), + diag::warn_printf_format_string_contains_null_char) + << getFormatStringRange(); +} + +const Expr *CheckPrintfHandler::getDataArg(unsigned i) const { + return TheCall->getArg(FirstDataArg + i); +} + +void CheckPrintfHandler::HandleFlags(const analyze_printf::FormatSpecifier &FS, + llvm::StringRef flag, + llvm::StringRef cspec, + const char *startSpecifier, + unsigned specifierLen) { + const analyze_printf::ConversionSpecifier &CS = FS.getConversionSpecifier(); + S.Diag(getLocationOfByte(CS.getStart()), diag::warn_printf_nonsensical_flag) + << flag << cspec << getFormatSpecifierRange(startSpecifier, specifierLen); +} + +bool +CheckPrintfHandler::HandleAmount(const analyze_printf::OptionalAmount &Amt, + unsigned k, const char *startSpecifier, + unsigned specifierLen) { + + if (Amt.hasDataArgument()) { + if (!HasVAListArg) { + unsigned argIndex = Amt.getArgIndex(); + if (argIndex >= NumDataArgs) { + S.Diag(getLocationOfByte(Amt.getStart()), + diag::warn_printf_asterisk_missing_arg) + << k << getFormatSpecifierRange(startSpecifier, specifierLen); + // Don't do any more checking. We will just emit + // spurious errors. + return false; + } + + // Type check the data argument. It should be an 'int'. + // Although not in conformance with C99, we also allow the argument to be + // an 'unsigned int' as that is a reasonably safe case. GCC also + // doesn't emit a warning for that case. + CoveredArgs.set(argIndex); + const Expr *Arg = getDataArg(argIndex); + QualType T = Arg->getType(); + + const analyze_printf::ArgTypeResult &ATR = Amt.getArgType(S.Context); + assert(ATR.isValid()); + + if (!ATR.matchesType(S.Context, T)) { + S.Diag(getLocationOfByte(Amt.getStart()), + diag::warn_printf_asterisk_wrong_type) + << k + << ATR.getRepresentativeType(S.Context) << T + << getFormatSpecifierRange(startSpecifier, specifierLen) + << Arg->getSourceRange(); + // Don't do any more checking. We will just emit + // spurious errors. + return false; + } + } + } + return true; +} + +bool +CheckPrintfHandler::HandleFormatSpecifier(const analyze_printf::FormatSpecifier + &FS, + const char *startSpecifier, + unsigned specifierLen) { + + using namespace analyze_printf; + const ConversionSpecifier &CS = FS.getConversionSpecifier(); + + if (atFirstArg) { + atFirstArg = false; + usesPositionalArgs = FS.usesPositionalArg(); + } + else if (usesPositionalArgs != FS.usesPositionalArg()) { + // Cannot mix-and-match positional and non-positional arguments. + S.Diag(getLocationOfByte(CS.getStart()), + diag::warn_printf_mix_positional_nonpositional_args) + << getFormatSpecifierRange(startSpecifier, specifierLen); + return false; + } + + // First check if the field width, precision, and conversion specifier + // have matching data arguments. + if (!HandleAmount(FS.getFieldWidth(), /* field width */ 0, + startSpecifier, specifierLen)) { + return false; + } + + if (!HandleAmount(FS.getPrecision(), /* precision */ 1, + startSpecifier, specifierLen)) { + return false; + } + + if (!CS.consumesDataArgument()) { + // FIXME: Technically specifying a precision or field width here + // makes no sense. Worth issuing a warning at some point. + return true; + } + + // Consume the argument. + unsigned argIndex = FS.getArgIndex(); + if (argIndex < NumDataArgs) { + // The check to see if the argIndex is valid will come later. + // We set the bit here because we may exit early from this + // function if we encounter some other error. + CoveredArgs.set(argIndex); + } + + // Check for using an Objective-C specific conversion specifier + // in a non-ObjC literal. + if (!IsObjCLiteral && CS.isObjCArg()) { + return HandleInvalidConversionSpecifier(FS, startSpecifier, specifierLen); + } + + // Are we using '%n'? Issue a warning about this being + // a possible security issue. + if (CS.getKind() == ConversionSpecifier::OutIntPtrArg) { + S.Diag(getLocationOfByte(CS.getStart()), diag::warn_printf_write_back) + << getFormatSpecifierRange(startSpecifier, specifierLen); + // Continue checking the other format specifiers. + return true; + } + + if (CS.getKind() == ConversionSpecifier::VoidPtrArg) { + if (FS.getPrecision().getHowSpecified() != OptionalAmount::NotSpecified) + S.Diag(getLocationOfByte(CS.getStart()), + diag::warn_printf_nonsensical_precision) + << CS.getCharacters() + << getFormatSpecifierRange(startSpecifier, specifierLen); + } + if (CS.getKind() == ConversionSpecifier::VoidPtrArg || + CS.getKind() == ConversionSpecifier::CStrArg) { + // FIXME: Instead of using "0", "+", etc., eventually get them from + // the FormatSpecifier. + if (FS.hasLeadingZeros()) + HandleFlags(FS, "0", CS.getCharacters(), startSpecifier, specifierLen); + if (FS.hasPlusPrefix()) + HandleFlags(FS, "+", CS.getCharacters(), startSpecifier, specifierLen); + if (FS.hasSpacePrefix()) + HandleFlags(FS, " ", CS.getCharacters(), startSpecifier, specifierLen); + } + + // The remaining checks depend on the data arguments. + if (HasVAListArg) + return true; + + if (argIndex >= NumDataArgs) { + if (FS.usesPositionalArg()) { + S.Diag(getLocationOfByte(CS.getStart()), + diag::warn_printf_positional_arg_exceeds_data_args) + << (argIndex+1) << NumDataArgs + << getFormatSpecifierRange(startSpecifier, specifierLen); + } + else { + S.Diag(getLocationOfByte(CS.getStart()), + diag::warn_printf_insufficient_data_args) + << getFormatSpecifierRange(startSpecifier, specifierLen); + } + + // Don't do any more checking. + return false; + } + + // Now type check the data expression that matches the + // format specifier. + const Expr *Ex = getDataArg(argIndex); + const analyze_printf::ArgTypeResult &ATR = FS.getArgType(S.Context); + if (ATR.isValid() && !ATR.matchesType(S.Context, Ex->getType())) { + // Check if we didn't match because of an implicit cast from a 'char' + // or 'short' to an 'int'. This is done because printf is a varargs + // function. + if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Ex)) + if (ICE->getType() == S.Context.IntTy) + if (ATR.matchesType(S.Context, ICE->getSubExpr()->getType())) + return true; + + S.Diag(getLocationOfByte(CS.getStart()), + diag::warn_printf_conversion_argument_type_mismatch) + << ATR.getRepresentativeType(S.Context) << Ex->getType() + << getFormatSpecifierRange(startSpecifier, specifierLen) + << Ex->getSourceRange(); + } + + return true; +} + +void CheckPrintfHandler::DoneProcessing() { + // Does the number of data arguments exceed the number of + // format conversions in the format string? + if (!HasVAListArg) { + // Find any arguments that weren't covered. + CoveredArgs.flip(); + signed notCoveredArg = CoveredArgs.find_first(); + if (notCoveredArg >= 0) { + assert((unsigned)notCoveredArg < NumDataArgs); + S.Diag(getDataArg((unsigned) notCoveredArg)->getLocStart(), + diag::warn_printf_data_arg_not_used) + << getFormatStringRange(); + } + } +} + +void Sema::CheckPrintfString(const StringLiteral *FExpr, + const Expr *OrigFormatExpr, + const CallExpr *TheCall, bool HasVAListArg, + unsigned format_idx, unsigned firstDataArg) { + + // CHECK: is the format string a wide literal? + if (FExpr->isWide()) { + Diag(FExpr->getLocStart(), + diag::warn_printf_format_string_is_wide_literal) + << OrigFormatExpr->getSourceRange(); + return; + } + + // Str - The format string. NOTE: this is NOT null-terminated! + const char *Str = FExpr->getStrData(); + + // CHECK: empty format string? + unsigned StrLen = FExpr->getByteLength(); + + if (StrLen == 0) { + Diag(FExpr->getLocStart(), diag::warn_printf_empty_format_string) + << OrigFormatExpr->getSourceRange(); + return; + } + + CheckPrintfHandler H(*this, FExpr, OrigFormatExpr, firstDataArg, + TheCall->getNumArgs() - firstDataArg, + isa<ObjCStringLiteral>(OrigFormatExpr), Str, + HasVAListArg, TheCall, format_idx); + + if (!analyze_printf::ParseFormatString(H, Str, Str + StrLen)) + H.DoneProcessing(); +} + +//===--- CHECK: Return Address of Stack Variable --------------------------===// + +static DeclRefExpr* EvalVal(Expr *E); +static DeclRefExpr* EvalAddr(Expr* E); + +/// CheckReturnStackAddr - Check if a return statement returns the address +/// of a stack variable. +void +Sema::CheckReturnStackAddr(Expr *RetValExp, QualType lhsType, + SourceLocation ReturnLoc) { + + // Perform checking for returned stack addresses. + if (lhsType->isPointerType() || lhsType->isBlockPointerType()) { + if (DeclRefExpr *DR = EvalAddr(RetValExp)) + Diag(DR->getLocStart(), diag::warn_ret_stack_addr) + << DR->getDecl()->getDeclName() << RetValExp->getSourceRange(); + + // Skip over implicit cast expressions when checking for block expressions. + RetValExp = RetValExp->IgnoreParenCasts(); + + if (BlockExpr *C = dyn_cast<BlockExpr>(RetValExp)) + if (C->hasBlockDeclRefExprs()) + Diag(C->getLocStart(), diag::err_ret_local_block) + << C->getSourceRange(); + + if (AddrLabelExpr *ALE = dyn_cast<AddrLabelExpr>(RetValExp)) + Diag(ALE->getLocStart(), diag::warn_ret_addr_label) + << ALE->getSourceRange(); + + } else if (lhsType->isReferenceType()) { + // Perform checking for stack values returned by reference. + // Check for a reference to the stack + if (DeclRefExpr *DR = EvalVal(RetValExp)) + Diag(DR->getLocStart(), diag::warn_ret_stack_ref) + << DR->getDecl()->getDeclName() << RetValExp->getSourceRange(); + } +} + +/// EvalAddr - EvalAddr and EvalVal are mutually recursive functions that +/// check if the expression in a return statement evaluates to an address +/// to a location on the stack. The recursion is used to traverse the +/// AST of the return expression, with recursion backtracking when we +/// encounter a subexpression that (1) clearly does not lead to the address +/// of a stack variable or (2) is something we cannot determine leads to +/// the address of a stack variable based on such local checking. +/// +/// EvalAddr processes expressions that are pointers that are used as +/// references (and not L-values). EvalVal handles all other values. +/// At the base case of the recursion is a check for a DeclRefExpr* in +/// the refers to a stack variable. +/// +/// This implementation handles: +/// +/// * pointer-to-pointer casts +/// * implicit conversions from array references to pointers +/// * taking the address of fields +/// * arbitrary interplay between "&" and "*" operators +/// * pointer arithmetic from an address of a stack variable +/// * taking the address of an array element where the array is on the stack +static DeclRefExpr* EvalAddr(Expr *E) { + // We should only be called for evaluating pointer expressions. + assert((E->getType()->isAnyPointerType() || + E->getType()->isBlockPointerType() || + E->getType()->isObjCQualifiedIdType()) && + "EvalAddr only works on pointers"); + + // Our "symbolic interpreter" is just a dispatch off the currently + // viewed AST node. We then recursively traverse the AST by calling + // EvalAddr and EvalVal appropriately. + switch (E->getStmtClass()) { + case Stmt::ParenExprClass: + // Ignore parentheses. + return EvalAddr(cast<ParenExpr>(E)->getSubExpr()); + + case Stmt::UnaryOperatorClass: { + // The only unary operator that make sense to handle here + // is AddrOf. All others don't make sense as pointers. + UnaryOperator *U = cast<UnaryOperator>(E); + + if (U->getOpcode() == UnaryOperator::AddrOf) + return EvalVal(U->getSubExpr()); + else + return NULL; + } + + case Stmt::BinaryOperatorClass: { + // Handle pointer arithmetic. All other binary operators are not valid + // in this context. + BinaryOperator *B = cast<BinaryOperator>(E); + BinaryOperator::Opcode op = B->getOpcode(); + + if (op != BinaryOperator::Add && op != BinaryOperator::Sub) + return NULL; + + Expr *Base = B->getLHS(); + + // Determine which argument is the real pointer base. It could be + // the RHS argument instead of the LHS. + if (!Base->getType()->isPointerType()) Base = B->getRHS(); + + assert (Base->getType()->isPointerType()); + return EvalAddr(Base); + } + + // For conditional operators we need to see if either the LHS or RHS are + // valid DeclRefExpr*s. If one of them is valid, we return it. + case Stmt::ConditionalOperatorClass: { + ConditionalOperator *C = cast<ConditionalOperator>(E); + + // Handle the GNU extension for missing LHS. + if (Expr *lhsExpr = C->getLHS()) + if (DeclRefExpr* LHS = EvalAddr(lhsExpr)) + return LHS; + + return EvalAddr(C->getRHS()); + } + + // For casts, we need to handle conversions from arrays to + // pointer values, and pointer-to-pointer conversions. + case Stmt::ImplicitCastExprClass: + case Stmt::CStyleCastExprClass: + case Stmt::CXXFunctionalCastExprClass: { + Expr* SubExpr = cast<CastExpr>(E)->getSubExpr(); + QualType T = SubExpr->getType(); + + if (SubExpr->getType()->isPointerType() || + SubExpr->getType()->isBlockPointerType() || + SubExpr->getType()->isObjCQualifiedIdType()) + return EvalAddr(SubExpr); + else if (T->isArrayType()) + return EvalVal(SubExpr); + else + return 0; + } + + // C++ casts. For dynamic casts, static casts, and const casts, we + // are always converting from a pointer-to-pointer, so we just blow + // through the cast. In the case the dynamic cast doesn't fail (and + // return NULL), we take the conservative route and report cases + // where we return the address of a stack variable. For Reinterpre + // FIXME: The comment about is wrong; we're not always converting + // from pointer to pointer. I'm guessing that this code should also + // handle references to objects. + case Stmt::CXXStaticCastExprClass: + case Stmt::CXXDynamicCastExprClass: + case Stmt::CXXConstCastExprClass: + case Stmt::CXXReinterpretCastExprClass: { + Expr *S = cast<CXXNamedCastExpr>(E)->getSubExpr(); + if (S->getType()->isPointerType() || S->getType()->isBlockPointerType()) + return EvalAddr(S); + else + return NULL; + } + + // Everything else: we simply don't reason about them. + default: + return NULL; + } +} + + +/// EvalVal - This function is complements EvalAddr in the mutual recursion. +/// See the comments for EvalAddr for more details. +static DeclRefExpr* EvalVal(Expr *E) { + + // We should only be called for evaluating non-pointer expressions, or + // expressions with a pointer type that are not used as references but instead + // are l-values (e.g., DeclRefExpr with a pointer type). + + // Our "symbolic interpreter" is just a dispatch off the currently + // viewed AST node. We then recursively traverse the AST by calling + // EvalAddr and EvalVal appropriately. + switch (E->getStmtClass()) { + case Stmt::DeclRefExprClass: { + // DeclRefExpr: the base case. When we hit a DeclRefExpr we are looking + // at code that refers to a variable's name. We check if it has local + // storage within the function, and if so, return the expression. + DeclRefExpr *DR = cast<DeclRefExpr>(E); + + if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl())) + if (V->hasLocalStorage() && !V->getType()->isReferenceType()) return DR; + + return NULL; + } + + case Stmt::ParenExprClass: + // Ignore parentheses. + return EvalVal(cast<ParenExpr>(E)->getSubExpr()); + + case Stmt::UnaryOperatorClass: { + // The only unary operator that make sense to handle here + // is Deref. All others don't resolve to a "name." This includes + // handling all sorts of rvalues passed to a unary operator. + UnaryOperator *U = cast<UnaryOperator>(E); + + if (U->getOpcode() == UnaryOperator::Deref) + return EvalAddr(U->getSubExpr()); + + return NULL; + } + + case Stmt::ArraySubscriptExprClass: { + // Array subscripts are potential references to data on the stack. We + // retrieve the DeclRefExpr* for the array variable if it indeed + // has local storage. + return EvalAddr(cast<ArraySubscriptExpr>(E)->getBase()); + } + + case Stmt::ConditionalOperatorClass: { + // For conditional operators we need to see if either the LHS or RHS are + // non-NULL DeclRefExpr's. If one is non-NULL, we return it. + ConditionalOperator *C = cast<ConditionalOperator>(E); + + // Handle the GNU extension for missing LHS. + if (Expr *lhsExpr = C->getLHS()) + if (DeclRefExpr *LHS = EvalVal(lhsExpr)) + return LHS; + + return EvalVal(C->getRHS()); + } + + // Accesses to members are potential references to data on the stack. + case Stmt::MemberExprClass: { + MemberExpr *M = cast<MemberExpr>(E); + + // Check for indirect access. We only want direct field accesses. + if (!M->isArrow()) + return EvalVal(M->getBase()); + else + return NULL; + } + + // Everything else: we simply don't reason about them. + default: + return NULL; + } +} + +//===--- CHECK: Floating-Point comparisons (-Wfloat-equal) ---------------===// + +/// Check for comparisons of floating point operands using != and ==. +/// Issue a warning if these are no self-comparisons, as they are not likely +/// to do what the programmer intended. +void Sema::CheckFloatComparison(SourceLocation loc, Expr* lex, Expr *rex) { + bool EmitWarning = true; + + Expr* LeftExprSansParen = lex->IgnoreParens(); + Expr* RightExprSansParen = rex->IgnoreParens(); + + // Special case: check for x == x (which is OK). + // Do not emit warnings for such cases. + if (DeclRefExpr* DRL = dyn_cast<DeclRefExpr>(LeftExprSansParen)) + if (DeclRefExpr* DRR = dyn_cast<DeclRefExpr>(RightExprSansParen)) + if (DRL->getDecl() == DRR->getDecl()) + EmitWarning = false; + + + // Special case: check for comparisons against literals that can be exactly + // represented by APFloat. In such cases, do not emit a warning. This + // is a heuristic: often comparison against such literals are used to + // detect if a value in a variable has not changed. This clearly can + // lead to false negatives. + if (EmitWarning) { + if (FloatingLiteral* FLL = dyn_cast<FloatingLiteral>(LeftExprSansParen)) { + if (FLL->isExact()) + EmitWarning = false; + } else + if (FloatingLiteral* FLR = dyn_cast<FloatingLiteral>(RightExprSansParen)){ + if (FLR->isExact()) + EmitWarning = false; + } + } + + // Check for comparisons with builtin types. + if (EmitWarning) + if (CallExpr* CL = dyn_cast<CallExpr>(LeftExprSansParen)) + if (CL->isBuiltinCall(Context)) + EmitWarning = false; + + if (EmitWarning) + if (CallExpr* CR = dyn_cast<CallExpr>(RightExprSansParen)) + if (CR->isBuiltinCall(Context)) + EmitWarning = false; + + // Emit the diagnostic. + if (EmitWarning) + Diag(loc, diag::warn_floatingpoint_eq) + << lex->getSourceRange() << rex->getSourceRange(); +} + +//===--- CHECK: Integer mixed-sign comparisons (-Wsign-compare) --------===// +//===--- CHECK: Lossy implicit conversions (-Wconversion) --------------===// + +namespace { + +/// Structure recording the 'active' range of an integer-valued +/// expression. +struct IntRange { + /// The number of bits active in the int. + unsigned Width; + + /// True if the int is known not to have negative values. + bool NonNegative; + + IntRange() {} + IntRange(unsigned Width, bool NonNegative) + : Width(Width), NonNegative(NonNegative) + {} + + // Returns the range of the bool type. + static IntRange forBoolType() { + return IntRange(1, true); + } + + // Returns the range of an integral type. + static IntRange forType(ASTContext &C, QualType T) { + return forCanonicalType(C, T->getCanonicalTypeInternal().getTypePtr()); + } + + // Returns the range of an integeral type based on its canonical + // representation. + static IntRange forCanonicalType(ASTContext &C, const Type *T) { + assert(T->isCanonicalUnqualified()); + + if (const VectorType *VT = dyn_cast<VectorType>(T)) + T = VT->getElementType().getTypePtr(); + if (const ComplexType *CT = dyn_cast<ComplexType>(T)) + T = CT->getElementType().getTypePtr(); + + if (const EnumType *ET = dyn_cast<EnumType>(T)) { + EnumDecl *Enum = ET->getDecl(); + unsigned NumPositive = Enum->getNumPositiveBits(); + unsigned NumNegative = Enum->getNumNegativeBits(); + + return IntRange(std::max(NumPositive, NumNegative), NumNegative == 0); + } + + const BuiltinType *BT = cast<BuiltinType>(T); + assert(BT->isInteger()); + + return IntRange(C.getIntWidth(QualType(T, 0)), BT->isUnsignedInteger()); + } + + // Returns the supremum of two ranges: i.e. their conservative merge. + static IntRange join(IntRange L, IntRange R) { + return IntRange(std::max(L.Width, R.Width), + L.NonNegative && R.NonNegative); + } + + // Returns the infinum of two ranges: i.e. their aggressive merge. + static IntRange meet(IntRange L, IntRange R) { + return IntRange(std::min(L.Width, R.Width), + L.NonNegative || R.NonNegative); + } +}; + +IntRange GetValueRange(ASTContext &C, llvm::APSInt &value, unsigned MaxWidth) { + if (value.isSigned() && value.isNegative()) + return IntRange(value.getMinSignedBits(), false); + + if (value.getBitWidth() > MaxWidth) + value.trunc(MaxWidth); + + // isNonNegative() just checks the sign bit without considering + // signedness. + return IntRange(value.getActiveBits(), true); +} + +IntRange GetValueRange(ASTContext &C, APValue &result, QualType Ty, + unsigned MaxWidth) { + if (result.isInt()) + return GetValueRange(C, result.getInt(), MaxWidth); + + if (result.isVector()) { + IntRange R = GetValueRange(C, result.getVectorElt(0), Ty, MaxWidth); + for (unsigned i = 1, e = result.getVectorLength(); i != e; ++i) { + IntRange El = GetValueRange(C, result.getVectorElt(i), Ty, MaxWidth); + R = IntRange::join(R, El); + } + return R; + } + + if (result.isComplexInt()) { + IntRange R = GetValueRange(C, result.getComplexIntReal(), MaxWidth); + IntRange I = GetValueRange(C, result.getComplexIntImag(), MaxWidth); + return IntRange::join(R, I); + } + + // This can happen with lossless casts to intptr_t of "based" lvalues. + // Assume it might use arbitrary bits. + // FIXME: The only reason we need to pass the type in here is to get + // the sign right on this one case. It would be nice if APValue + // preserved this. + assert(result.isLValue()); + return IntRange(MaxWidth, Ty->isUnsignedIntegerType()); +} + +/// Pseudo-evaluate the given integer expression, estimating the +/// range of values it might take. +/// +/// \param MaxWidth - the width to which the value will be truncated +IntRange GetExprRange(ASTContext &C, Expr *E, unsigned MaxWidth) { + E = E->IgnoreParens(); + + // Try a full evaluation first. + Expr::EvalResult result; + if (E->Evaluate(result, C)) + return GetValueRange(C, result.Val, E->getType(), MaxWidth); + + // I think we only want to look through implicit casts here; if the + // user has an explicit widening cast, we should treat the value as + // being of the new, wider type. + if (ImplicitCastExpr *CE = dyn_cast<ImplicitCastExpr>(E)) { + if (CE->getCastKind() == CastExpr::CK_NoOp) + return GetExprRange(C, CE->getSubExpr(), MaxWidth); + + IntRange OutputTypeRange = IntRange::forType(C, CE->getType()); + + bool isIntegerCast = (CE->getCastKind() == CastExpr::CK_IntegralCast); + if (!isIntegerCast && CE->getCastKind() == CastExpr::CK_Unknown) + isIntegerCast = CE->getSubExpr()->getType()->isIntegerType(); + + // Assume that non-integer casts can span the full range of the type. + if (!isIntegerCast) + return OutputTypeRange; + + IntRange SubRange + = GetExprRange(C, CE->getSubExpr(), + std::min(MaxWidth, OutputTypeRange.Width)); + + // Bail out if the subexpr's range is as wide as the cast type. + if (SubRange.Width >= OutputTypeRange.Width) + return OutputTypeRange; + + // Otherwise, we take the smaller width, and we're non-negative if + // either the output type or the subexpr is. + return IntRange(SubRange.Width, + SubRange.NonNegative || OutputTypeRange.NonNegative); + } + + if (ConditionalOperator *CO = dyn_cast<ConditionalOperator>(E)) { + // If we can fold the condition, just take that operand. + bool CondResult; + if (CO->getCond()->EvaluateAsBooleanCondition(CondResult, C)) + return GetExprRange(C, CondResult ? CO->getTrueExpr() + : CO->getFalseExpr(), + MaxWidth); + + // Otherwise, conservatively merge. + IntRange L = GetExprRange(C, CO->getTrueExpr(), MaxWidth); + IntRange R = GetExprRange(C, CO->getFalseExpr(), MaxWidth); + return IntRange::join(L, R); + } + + if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) { + switch (BO->getOpcode()) { + + // Boolean-valued operations are single-bit and positive. + case BinaryOperator::LAnd: + case BinaryOperator::LOr: + case BinaryOperator::LT: + case BinaryOperator::GT: + case BinaryOperator::LE: + case BinaryOperator::GE: + case BinaryOperator::EQ: + case BinaryOperator::NE: + return IntRange::forBoolType(); + + // The type of these compound assignments is the type of the LHS, + // so the RHS is not necessarily an integer. + case BinaryOperator::MulAssign: + case BinaryOperator::DivAssign: + case BinaryOperator::RemAssign: + case BinaryOperator::AddAssign: + case BinaryOperator::SubAssign: + return IntRange::forType(C, E->getType()); + + // Operations with opaque sources are black-listed. + case BinaryOperator::PtrMemD: + case BinaryOperator::PtrMemI: + return IntRange::forType(C, E->getType()); + + // Bitwise-and uses the *infinum* of the two source ranges. + case BinaryOperator::And: + case BinaryOperator::AndAssign: + return IntRange::meet(GetExprRange(C, BO->getLHS(), MaxWidth), + GetExprRange(C, BO->getRHS(), MaxWidth)); + + // Left shift gets black-listed based on a judgement call. + case BinaryOperator::Shl: + // ...except that we want to treat '1 << (blah)' as logically + // positive. It's an important idiom. + if (IntegerLiteral *I + = dyn_cast<IntegerLiteral>(BO->getLHS()->IgnoreParenCasts())) { + if (I->getValue() == 1) { + IntRange R = IntRange::forType(C, E->getType()); + return IntRange(R.Width, /*NonNegative*/ true); + } + } + // fallthrough + + case BinaryOperator::ShlAssign: + return IntRange::forType(C, E->getType()); + + // Right shift by a constant can narrow its left argument. + case BinaryOperator::Shr: + case BinaryOperator::ShrAssign: { + IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth); + + // If the shift amount is a positive constant, drop the width by + // that much. + llvm::APSInt shift; + if (BO->getRHS()->isIntegerConstantExpr(shift, C) && + shift.isNonNegative()) { + unsigned zext = shift.getZExtValue(); + if (zext >= L.Width) + L.Width = (L.NonNegative ? 0 : 1); + else + L.Width -= zext; + } + + return L; + } + + // Comma acts as its right operand. + case BinaryOperator::Comma: + return GetExprRange(C, BO->getRHS(), MaxWidth); + + // Black-list pointer subtractions. + case BinaryOperator::Sub: + if (BO->getLHS()->getType()->isPointerType()) + return IntRange::forType(C, E->getType()); + // fallthrough + + default: + break; + } + + // Treat every other operator as if it were closed on the + // narrowest type that encompasses both operands. + IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth); + IntRange R = GetExprRange(C, BO->getRHS(), MaxWidth); + return IntRange::join(L, R); + } + + if (UnaryOperator *UO = dyn_cast<UnaryOperator>(E)) { + switch (UO->getOpcode()) { + // Boolean-valued operations are white-listed. + case UnaryOperator::LNot: + return IntRange::forBoolType(); + + // Operations with opaque sources are black-listed. + case UnaryOperator::Deref: + case UnaryOperator::AddrOf: // should be impossible + case UnaryOperator::OffsetOf: + return IntRange::forType(C, E->getType()); + + default: + return GetExprRange(C, UO->getSubExpr(), MaxWidth); + } + } + + if (dyn_cast<OffsetOfExpr>(E)) { + IntRange::forType(C, E->getType()); + } + + FieldDecl *BitField = E->getBitField(); + if (BitField) { + llvm::APSInt BitWidthAP = BitField->getBitWidth()->EvaluateAsInt(C); + unsigned BitWidth = BitWidthAP.getZExtValue(); + + return IntRange(BitWidth, BitField->getType()->isUnsignedIntegerType()); + } + + return IntRange::forType(C, E->getType()); +} + +IntRange GetExprRange(ASTContext &C, Expr *E) { + return GetExprRange(C, E, C.getIntWidth(E->getType())); +} + +/// Checks whether the given value, which currently has the given +/// source semantics, has the same value when coerced through the +/// target semantics. +bool IsSameFloatAfterCast(const llvm::APFloat &value, + const llvm::fltSemantics &Src, + const llvm::fltSemantics &Tgt) { + llvm::APFloat truncated = value; + + bool ignored; + truncated.convert(Src, llvm::APFloat::rmNearestTiesToEven, &ignored); + truncated.convert(Tgt, llvm::APFloat::rmNearestTiesToEven, &ignored); + + return truncated.bitwiseIsEqual(value); +} + +/// Checks whether the given value, which currently has the given +/// source semantics, has the same value when coerced through the +/// target semantics. +/// +/// The value might be a vector of floats (or a complex number). +bool IsSameFloatAfterCast(const APValue &value, + const llvm::fltSemantics &Src, + const llvm::fltSemantics &Tgt) { + if (value.isFloat()) + return IsSameFloatAfterCast(value.getFloat(), Src, Tgt); + + if (value.isVector()) { + for (unsigned i = 0, e = value.getVectorLength(); i != e; ++i) + if (!IsSameFloatAfterCast(value.getVectorElt(i), Src, Tgt)) + return false; + return true; + } + + assert(value.isComplexFloat()); + return (IsSameFloatAfterCast(value.getComplexFloatReal(), Src, Tgt) && + IsSameFloatAfterCast(value.getComplexFloatImag(), Src, Tgt)); +} + +void AnalyzeImplicitConversions(Sema &S, Expr *E); + +bool IsZero(Sema &S, Expr *E) { + llvm::APSInt Value; + return E->isIntegerConstantExpr(Value, S.Context) && Value == 0; +} + +void CheckTrivialUnsignedComparison(Sema &S, BinaryOperator *E) { + BinaryOperator::Opcode op = E->getOpcode(); + if (op == BinaryOperator::LT && IsZero(S, E->getRHS())) { + S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison) + << "< 0" << "false" + << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); + } else if (op == BinaryOperator::GE && IsZero(S, E->getRHS())) { + S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison) + << ">= 0" << "true" + << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); + } else if (op == BinaryOperator::GT && IsZero(S, E->getLHS())) { + S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison) + << "0 >" << "false" + << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); + } else if (op == BinaryOperator::LE && IsZero(S, E->getLHS())) { + S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison) + << "0 <=" << "true" + << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); + } +} + +/// Analyze the operands of the given comparison. Implements the +/// fallback case from AnalyzeComparison. +void AnalyzeImpConvsInComparison(Sema &S, BinaryOperator *E) { + AnalyzeImplicitConversions(S, E->getLHS()); + AnalyzeImplicitConversions(S, E->getRHS()); +} + +/// \brief Implements -Wsign-compare. +/// +/// \param lex the left-hand expression +/// \param rex the right-hand expression +/// \param OpLoc the location of the joining operator +/// \param BinOpc binary opcode or 0 +void AnalyzeComparison(Sema &S, BinaryOperator *E) { + // The type the comparison is being performed in. + QualType T = E->getLHS()->getType(); + assert(S.Context.hasSameUnqualifiedType(T, E->getRHS()->getType()) + && "comparison with mismatched types"); + + // We don't do anything special if this isn't an unsigned integral + // comparison: we're only interested in integral comparisons, and + // signed comparisons only happen in cases we don't care to warn about. + if (!T->isUnsignedIntegerType()) + return AnalyzeImpConvsInComparison(S, E); + + Expr *lex = E->getLHS()->IgnoreParenImpCasts(); + Expr *rex = E->getRHS()->IgnoreParenImpCasts(); + + // Check to see if one of the (unmodified) operands is of different + // signedness. + Expr *signedOperand, *unsignedOperand; + if (lex->getType()->isSignedIntegerType()) { + assert(!rex->getType()->isSignedIntegerType() && + "unsigned comparison between two signed integer expressions?"); + signedOperand = lex; + unsignedOperand = rex; + } else if (rex->getType()->isSignedIntegerType()) { + signedOperand = rex; + unsignedOperand = lex; + } else { + CheckTrivialUnsignedComparison(S, E); + return AnalyzeImpConvsInComparison(S, E); + } + + // Otherwise, calculate the effective range of the signed operand. + IntRange signedRange = GetExprRange(S.Context, signedOperand); + + // Go ahead and analyze implicit conversions in the operands. Note + // that we skip the implicit conversions on both sides. + AnalyzeImplicitConversions(S, lex); + AnalyzeImplicitConversions(S, rex); + + // If the signed range is non-negative, -Wsign-compare won't fire, + // but we should still check for comparisons which are always true + // or false. + if (signedRange.NonNegative) + return CheckTrivialUnsignedComparison(S, E); + + // For (in)equality comparisons, if the unsigned operand is a + // constant which cannot collide with a overflowed signed operand, + // then reinterpreting the signed operand as unsigned will not + // change the result of the comparison. + if (E->isEqualityOp()) { + unsigned comparisonWidth = S.Context.getIntWidth(T); + IntRange unsignedRange = GetExprRange(S.Context, unsignedOperand); + + // We should never be unable to prove that the unsigned operand is + // non-negative. + assert(unsignedRange.NonNegative && "unsigned range includes negative?"); + + if (unsignedRange.Width < comparisonWidth) + return; + } + + S.Diag(E->getOperatorLoc(), diag::warn_mixed_sign_comparison) + << lex->getType() << rex->getType() + << lex->getSourceRange() << rex->getSourceRange(); +} + +/// Diagnose an implicit cast; purely a helper for CheckImplicitConversion. +void DiagnoseImpCast(Sema &S, Expr *E, QualType T, unsigned diag) { + S.Diag(E->getExprLoc(), diag) << E->getType() << T << E->getSourceRange(); +} + +void CheckImplicitConversion(Sema &S, Expr *E, QualType T, + bool *ICContext = 0) { + if (E->isTypeDependent() || E->isValueDependent()) return; + + const Type *Source = S.Context.getCanonicalType(E->getType()).getTypePtr(); + const Type *Target = S.Context.getCanonicalType(T).getTypePtr(); + if (Source == Target) return; + if (Target->isDependentType()) return; + + // Never diagnose implicit casts to bool. + if (Target->isSpecificBuiltinType(BuiltinType::Bool)) + return; + + // Strip vector types. + if (isa<VectorType>(Source)) { + if (!isa<VectorType>(Target)) + return DiagnoseImpCast(S, E, T, diag::warn_impcast_vector_scalar); + + Source = cast<VectorType>(Source)->getElementType().getTypePtr(); + Target = cast<VectorType>(Target)->getElementType().getTypePtr(); + } + + // Strip complex types. + if (isa<ComplexType>(Source)) { + if (!isa<ComplexType>(Target)) + return DiagnoseImpCast(S, E, T, diag::warn_impcast_complex_scalar); + + Source = cast<ComplexType>(Source)->getElementType().getTypePtr(); + Target = cast<ComplexType>(Target)->getElementType().getTypePtr(); + } + + const BuiltinType *SourceBT = dyn_cast<BuiltinType>(Source); + const BuiltinType *TargetBT = dyn_cast<BuiltinType>(Target); + + // If the source is floating point... + if (SourceBT && SourceBT->isFloatingPoint()) { + // ...and the target is floating point... + if (TargetBT && TargetBT->isFloatingPoint()) { + // ...then warn if we're dropping FP rank. + + // Builtin FP kinds are ordered by increasing FP rank. + if (SourceBT->getKind() > TargetBT->getKind()) { + // Don't warn about float constants that are precisely + // representable in the target type. + Expr::EvalResult result; + if (E->Evaluate(result, S.Context)) { + // Value might be a float, a float vector, or a float complex. + if (IsSameFloatAfterCast(result.Val, + S.Context.getFloatTypeSemantics(QualType(TargetBT, 0)), + S.Context.getFloatTypeSemantics(QualType(SourceBT, 0)))) + return; + } + + DiagnoseImpCast(S, E, T, diag::warn_impcast_float_precision); + } + return; + } + + // If the target is integral, always warn. + if ((TargetBT && TargetBT->isInteger())) + // TODO: don't warn for integer values? + DiagnoseImpCast(S, E, T, diag::warn_impcast_float_integer); + + return; + } + + if (!Source->isIntegerType() || !Target->isIntegerType()) + return; + + IntRange SourceRange = GetExprRange(S.Context, E); + IntRange TargetRange = IntRange::forCanonicalType(S.Context, Target); + + if (SourceRange.Width > TargetRange.Width) { + // People want to build with -Wshorten-64-to-32 and not -Wconversion + // and by god we'll let them. + if (SourceRange.Width == 64 && TargetRange.Width == 32) + return DiagnoseImpCast(S, E, T, diag::warn_impcast_integer_64_32); + return DiagnoseImpCast(S, E, T, diag::warn_impcast_integer_precision); + } + + if ((TargetRange.NonNegative && !SourceRange.NonNegative) || + (!TargetRange.NonNegative && SourceRange.NonNegative && + SourceRange.Width == TargetRange.Width)) { + unsigned DiagID = diag::warn_impcast_integer_sign; + + // Traditionally, gcc has warned about this under -Wsign-compare. + // We also want to warn about it in -Wconversion. + // So if -Wconversion is off, use a completely identical diagnostic + // in the sign-compare group. + // The conditional-checking code will + if (ICContext) { + DiagID = diag::warn_impcast_integer_sign_conditional; + *ICContext = true; + } + + return DiagnoseImpCast(S, E, T, DiagID); + } + + return; +} + +void CheckConditionalOperator(Sema &S, ConditionalOperator *E, QualType T); + +void CheckConditionalOperand(Sema &S, Expr *E, QualType T, + bool &ICContext) { + E = E->IgnoreParenImpCasts(); + + if (isa<ConditionalOperator>(E)) + return CheckConditionalOperator(S, cast<ConditionalOperator>(E), T); + + AnalyzeImplicitConversions(S, E); + if (E->getType() != T) + return CheckImplicitConversion(S, E, T, &ICContext); + return; +} + +void CheckConditionalOperator(Sema &S, ConditionalOperator *E, QualType T) { + AnalyzeImplicitConversions(S, E->getCond()); + + bool Suspicious = false; + CheckConditionalOperand(S, E->getTrueExpr(), T, Suspicious); + CheckConditionalOperand(S, E->getFalseExpr(), T, Suspicious); + + // If -Wconversion would have warned about either of the candidates + // for a signedness conversion to the context type... + if (!Suspicious) return; + + // ...but it's currently ignored... + if (S.Diags.getDiagnosticLevel(diag::warn_impcast_integer_sign_conditional)) + return; + + // ...and -Wsign-compare isn't... + if (!S.Diags.getDiagnosticLevel(diag::warn_mixed_sign_conditional)) + return; + + // ...then check whether it would have warned about either of the + // candidates for a signedness conversion to the condition type. + if (E->getType() != T) { + Suspicious = false; + CheckImplicitConversion(S, E->getTrueExpr()->IgnoreParenImpCasts(), + E->getType(), &Suspicious); + if (!Suspicious) + CheckImplicitConversion(S, E->getFalseExpr()->IgnoreParenImpCasts(), + E->getType(), &Suspicious); + if (!Suspicious) + return; + } + + // If so, emit a diagnostic under -Wsign-compare. + Expr *lex = E->getTrueExpr()->IgnoreParenImpCasts(); + Expr *rex = E->getFalseExpr()->IgnoreParenImpCasts(); + S.Diag(E->getQuestionLoc(), diag::warn_mixed_sign_conditional) + << lex->getType() << rex->getType() + << lex->getSourceRange() << rex->getSourceRange(); +} + +/// AnalyzeImplicitConversions - Find and report any interesting +/// implicit conversions in the given expression. There are a couple +/// of competing diagnostics here, -Wconversion and -Wsign-compare. +void AnalyzeImplicitConversions(Sema &S, Expr *OrigE) { + QualType T = OrigE->getType(); + Expr *E = OrigE->IgnoreParenImpCasts(); + + // For conditional operators, we analyze the arguments as if they + // were being fed directly into the output. + if (isa<ConditionalOperator>(E)) { + ConditionalOperator *CO = cast<ConditionalOperator>(E); + CheckConditionalOperator(S, CO, T); + return; + } + + // Go ahead and check any implicit conversions we might have skipped. + // The non-canonical typecheck is just an optimization; + // CheckImplicitConversion will filter out dead implicit conversions. + if (E->getType() != T) + CheckImplicitConversion(S, E, T); + + // Now continue drilling into this expression. + + // Skip past explicit casts. + if (isa<ExplicitCastExpr>(E)) { + E = cast<ExplicitCastExpr>(E)->getSubExpr()->IgnoreParenImpCasts(); + return AnalyzeImplicitConversions(S, E); + } + + // Do a somewhat different check with comparison operators. + if (isa<BinaryOperator>(E) && cast<BinaryOperator>(E)->isComparisonOp()) + return AnalyzeComparison(S, cast<BinaryOperator>(E)); + + // These break the otherwise-useful invariant below. Fortunately, + // we don't really need to recurse into them, because any internal + // expressions should have been analyzed already when they were + // built into statements. + if (isa<StmtExpr>(E)) return; + + // Don't descend into unevaluated contexts. + if (isa<SizeOfAlignOfExpr>(E)) return; + + // Now just recurse over the expression's children. + for (Stmt::child_iterator I = E->child_begin(), IE = E->child_end(); + I != IE; ++I) + AnalyzeImplicitConversions(S, cast<Expr>(*I)); +} + +} // end anonymous namespace + +/// Diagnoses "dangerous" implicit conversions within the given +/// expression (which is a full expression). Implements -Wconversion +/// and -Wsign-compare. +void Sema::CheckImplicitConversions(Expr *E) { + // Don't diagnose in unevaluated contexts. + if (ExprEvalContexts.back().Context == Sema::Unevaluated) + return; + + // Don't diagnose for value- or type-dependent expressions. + if (E->isTypeDependent() || E->isValueDependent()) + return; + + AnalyzeImplicitConversions(*this, E); +} + +/// CheckParmsForFunctionDef - Check that the parameters of the given +/// function are appropriate for the definition of a function. This +/// takes care of any checks that cannot be performed on the +/// declaration itself, e.g., that the types of each of the function +/// parameters are complete. +bool Sema::CheckParmsForFunctionDef(FunctionDecl *FD) { + bool HasInvalidParm = false; + for (unsigned p = 0, NumParams = FD->getNumParams(); p < NumParams; ++p) { + ParmVarDecl *Param = FD->getParamDecl(p); + + // C99 6.7.5.3p4: the parameters in a parameter type list in a + // function declarator that is part of a function definition of + // that function shall not have incomplete type. + // + // This is also C++ [dcl.fct]p6. + if (!Param->isInvalidDecl() && + RequireCompleteType(Param->getLocation(), Param->getType(), + diag::err_typecheck_decl_incomplete_type)) { + Param->setInvalidDecl(); + HasInvalidParm = true; + } + + // C99 6.9.1p5: If the declarator includes a parameter type list, the + // declaration of each parameter shall include an identifier. + if (Param->getIdentifier() == 0 && + !Param->isImplicit() && + !getLangOptions().CPlusPlus) + Diag(Param->getLocation(), diag::err_parameter_name_omitted); + + // C99 6.7.5.3p12: + // If the function declarator is not part of a definition of that + // function, parameters may have incomplete type and may use the [*] + // notation in their sequences of declarator specifiers to specify + // variable length array types. + QualType PType = Param->getOriginalType(); + if (const ArrayType *AT = Context.getAsArrayType(PType)) { + if (AT->getSizeModifier() == ArrayType::Star) { + // FIXME: This diagnosic should point the the '[*]' if source-location + // information is added for it. + Diag(Param->getLocation(), diag::err_array_star_in_function_definition); + } + } + } + + return HasInvalidParm; +} |
