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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 | 3179 |
1 files changed, 3179 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..24cdaef --- /dev/null +++ b/contrib/llvm/tools/clang/lib/Sema/SemaChecking.cpp @@ -0,0 +1,3179 @@ +//===--- 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 "clang/Sema/Sema.h" +#include "clang/Sema/SemaInternal.h" +#include "clang/Sema/ScopeInfo.h" +#include "clang/Analysis/Analyses/FormatString.h" +#include "clang/AST/ASTContext.h" +#include "clang/AST/CharUnits.h" +#include "clang/AST/DeclCXX.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/Preprocessor.h" +#include "llvm/ADT/BitVector.h" +#include "llvm/ADT/STLExtras.h" +#include "llvm/Support/raw_ostream.h" +#include "clang/Basic/TargetBuiltins.h" +#include "clang/Basic/TargetInfo.h" +#include "clang/Basic/ConvertUTF.h" +#include <limits> +using namespace clang; +using namespace sema; + +SourceLocation Sema::getLocationOfStringLiteralByte(const StringLiteral *SL, + unsigned ByteNo) const { + return SL->getLocationOfByte(ByteNo, PP.getSourceManager(), + PP.getLangOptions(), PP.getTargetInfo()); +} + + +/// 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; +} + +ExprResult +Sema::CheckBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) { + ExprResult TheCallResult(Owned(TheCall)); + + // Find out if any arguments are required to be integer constant expressions. + unsigned ICEArguments = 0; + ASTContext::GetBuiltinTypeError Error; + Context.GetBuiltinType(BuiltinID, Error, &ICEArguments); + if (Error != ASTContext::GE_None) + ICEArguments = 0; // Don't diagnose previously diagnosed errors. + + // If any arguments are required to be ICE's, check and diagnose. + for (unsigned ArgNo = 0; ICEArguments != 0; ++ArgNo) { + // Skip arguments not required to be ICE's. + if ((ICEArguments & (1 << ArgNo)) == 0) continue; + + llvm::APSInt Result; + if (SemaBuiltinConstantArg(TheCall, ArgNo, Result)) + return true; + ICEArguments &= ~(1 << ArgNo); + } + + 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_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__builtin_constant_p: + if (TheCall->getNumArgs() == 0) + return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args) + << 0 /*function call*/ << 1 << 0 << TheCall->getSourceRange(); + if (TheCall->getNumArgs() > 1) + return Diag(TheCall->getArg(1)->getLocStart(), + diag::err_typecheck_call_too_many_args) + << 0 /*function call*/ << 1 << TheCall->getNumArgs() + << TheCall->getArg(1)->getSourceRange(); + 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: + return SemaBuiltinAtomicOverloaded(move(TheCallResult)); + } + + // Since the target specific builtins for each arch overlap, only check those + // of the arch we are compiling for. + if (BuiltinID >= Builtin::FirstTSBuiltin) { + switch (Context.Target.getTriple().getArch()) { + case llvm::Triple::arm: + case llvm::Triple::thumb: + if (CheckARMBuiltinFunctionCall(BuiltinID, TheCall)) + return ExprError(); + break; + default: + break; + } + } + + return move(TheCallResult); +} + +// Get the valid immediate range for the specified NEON type code. +static unsigned RFT(unsigned t, bool shift = false) { + bool quad = t & 0x10; + + switch (t & 0x7) { + case 0: // i8 + return shift ? 7 : (8 << (int)quad) - 1; + case 1: // i16 + return shift ? 15 : (4 << (int)quad) - 1; + case 2: // i32 + return shift ? 31 : (2 << (int)quad) - 1; + case 3: // i64 + return shift ? 63 : (1 << (int)quad) - 1; + case 4: // f32 + assert(!shift && "cannot shift float types!"); + return (2 << (int)quad) - 1; + case 5: // poly8 + return shift ? 7 : (8 << (int)quad) - 1; + case 6: // poly16 + return shift ? 15 : (4 << (int)quad) - 1; + case 7: // float16 + assert(!shift && "cannot shift float types!"); + return (4 << (int)quad) - 1; + } + return 0; +} + +bool Sema::CheckARMBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) { + llvm::APSInt Result; + + unsigned mask = 0; + unsigned TV = 0; + switch (BuiltinID) { +#define GET_NEON_OVERLOAD_CHECK +#include "clang/Basic/arm_neon.inc" +#undef GET_NEON_OVERLOAD_CHECK + } + + // For NEON intrinsics which are overloaded on vector element type, validate + // the immediate which specifies which variant to emit. + if (mask) { + unsigned ArgNo = TheCall->getNumArgs()-1; + if (SemaBuiltinConstantArg(TheCall, ArgNo, Result)) + return true; + + TV = Result.getLimitedValue(32); + if ((TV > 31) || (mask & (1 << TV)) == 0) + return Diag(TheCall->getLocStart(), diag::err_invalid_neon_type_code) + << TheCall->getArg(ArgNo)->getSourceRange(); + } + + // For NEON intrinsics which take an immediate value as part of the + // instruction, range check them here. + unsigned i = 0, l = 0, u = 0; + switch (BuiltinID) { + default: return false; + case ARM::BI__builtin_arm_ssat: i = 1; l = 1; u = 31; break; + case ARM::BI__builtin_arm_usat: i = 1; u = 31; break; + case ARM::BI__builtin_arm_vcvtr_f: + case ARM::BI__builtin_arm_vcvtr_d: i = 1; u = 1; break; +#define GET_NEON_IMMEDIATE_CHECK +#include "clang/Basic/arm_neon.inc" +#undef GET_NEON_IMMEDIATE_CHECK + }; + + // Check that the immediate argument is actually a constant. + if (SemaBuiltinConstantArg(TheCall, i, Result)) + return true; + + // Range check against the upper/lower values for this isntruction. + unsigned Val = Result.getZExtValue(); + if (Val < l || Val > (u + l)) + return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range) + << l << u+l << TheCall->getArg(i)->getSourceRange(); + + // FIXME: VFP Intrinsics should error if VFP not present. + return false; +} + +/// 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 and scanf checking. + for (specific_attr_iterator<FormatAttr> + i = FDecl->specific_attr_begin<FormatAttr>(), + e = FDecl->specific_attr_end<FormatAttr>(); i != e ; ++i) { + + const FormatAttr *Format = *i; + const bool b = Format->getType() == "scanf"; + if (b || CheckablePrintfAttr(Format, TheCall)) { + bool HasVAListArg = Format->getFirstArg() == 0; + CheckPrintfScanfArguments(TheCall, HasVAListArg, + Format->getFormatIdx() - 1, + HasVAListArg ? 0 : Format->getFirstArg() - 1, + !b); + } + } + + for (specific_attr_iterator<NonNullAttr> + i = FDecl->specific_attr_begin<NonNullAttr>(), + e = FDecl->specific_attr_end<NonNullAttr>(); i != e; ++i) { + CheckNonNullArguments(*i, 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; + + const bool b = Format->getType() == "scanf"; + if (!b && !CheckablePrintfAttr(Format, TheCall)) + return false; + + bool HasVAListArg = Format->getFirstArg() == 0; + CheckPrintfScanfArguments(TheCall, HasVAListArg, Format->getFormatIdx() - 1, + HasVAListArg ? 0 : Format->getFirstArg() - 1, !b); + + 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, +ExprResult +Sema::SemaBuiltinAtomicOverloaded(ExprResult TheCallResult) { + CallExpr *TheCall = (CallExpr *)TheCallResult.get(); + 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) { + Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args_at_least) + << 0 << 1 << TheCall->getNumArgs() + << TheCall->getCallee()->getSourceRange(); + return ExprError(); + } + + // 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. + // FIXME: We don't allow floating point scalars as input. + Expr *FirstArg = TheCall->getArg(0); + if (!FirstArg->getType()->isPointerType()) { + Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer) + << FirstArg->getType() << FirstArg->getSourceRange(); + return ExprError(); + } + + QualType ValType = + FirstArg->getType()->getAs<PointerType>()->getPointeeType(); + if (!ValType->isIntegerType() && !ValType->isAnyPointerType() && + !ValType->isBlockPointerType()) { + Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer_intptr) + << FirstArg->getType() << FirstArg->getSourceRange(); + return ExprError(); + } + + // The majority of builtins return a value, but a few have special return + // types, so allow them to override appropriately below. + QualType ResultType = ValType; + + // 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: + Diag(DRE->getLocStart(), diag::err_atomic_builtin_pointer_size) + << FirstArg->getType() << FirstArg->getSourceRange(); + return ExprError(); + } + + // 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; + ResultType = Context.BoolTy; + break; + case Builtin::BI__sync_lock_test_and_set: BuiltinIndex = 12; break; + case Builtin::BI__sync_lock_release: + BuiltinIndex = 13; + NumFixed = 0; + ResultType = Context.VoidTy; + 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) { + Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args_at_least) + << 0 << 1+NumFixed << TheCall->getNumArgs() + << TheCall->getCallee()->getSourceRange(); + return ExprError(); + } + + // 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())); + + // The first argument --- the pointer --- has a fixed type; we + // deduce the types of the rest of the arguments accordingly. Walk + // the remaining arguments, converting them to the deduced value 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); + 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. + CastKind Kind = CK_Invalid; + ExprValueKind VK = VK_RValue; + CXXCastPath BasePath; + if (CheckCastTypes(Arg->getSourceRange(), ValType, Arg, Kind, VK, BasePath)) + return ExprError(); + + // 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, VK, &BasePath); + 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 original value type. This + // is arbitrary, but the codegen for these builtins ins design to handle it + // gracefully. + TheCall->setType(ResultType); + + return move(TheCallResult); +} + + +/// CheckObjCString - Checks that the argument to the builtin +/// CFString constructor is correct +/// 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; + } + + size_t NulPos = Literal->getString().find('\0'); + if (NulPos != llvm::StringRef::npos) { + Diag(getLocationOfStringLiteralByte(Literal, NulPos), + diag::warn_cfstring_literal_contains_nul_character) + << Arg->getSourceRange(); + } + if (Literal->containsNonAsciiOrNull()) { + llvm::StringRef String = Literal->getString(); + unsigned NumBytes = String.size(); + llvm::SmallVector<UTF16, 128> ToBuf(NumBytes); + const UTF8 *FromPtr = (UTF8 *)String.data(); + UTF16 *ToPtr = &ToBuf[0]; + + ConversionResult Result = ConvertUTF8toUTF16(&FromPtr, FromPtr + NumBytes, + &ToPtr, ToPtr + NumBytes, + strictConversion); + // Check for conversion failure. + if (Result != conversionOK) + Diag(Arg->getLocStart(), + diag::warn_cfstring_truncated) << Arg->getSourceRange(); + } + 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->TheDecl->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); + TheCall->setArg(NumArgs-1, CastArg); + OrigArg = CastArg; + } + } + + return false; +} + +/// SemaBuiltinShuffleVector - Handle __builtin_shufflevector. +// This is declared to take (...), so we have to check everything. +ExprResult Sema::SemaBuiltinShuffleVector(CallExpr *TheCall) { + if (TheCall->getNumArgs() < 2) + return ExprError(Diag(TheCall->getLocEnd(), + diag::err_typecheck_call_too_few_args_at_least) + << 0 /*function call*/ << 2 << TheCall->getNumArgs() + << TheCall->getSourceRange()); + + // Determine which of the following types of shufflevector we're checking: + // 1) unary, vector mask: (lhs, mask) + // 2) binary, vector mask: (lhs, rhs, mask) + // 3) binary, scalar mask: (lhs, rhs, index, ..., index) + QualType resType = TheCall->getArg(0)->getType(); + unsigned numElements = 0; + + if (!TheCall->getArg(0)->isTypeDependent() && + !TheCall->getArg(1)->isTypeDependent()) { + QualType LHSType = TheCall->getArg(0)->getType(); + QualType RHSType = TheCall->getArg(1)->getType(); + + if (!LHSType->isVectorType() || !RHSType->isVectorType()) { + Diag(TheCall->getLocStart(), diag::err_shufflevector_non_vector) + << SourceRange(TheCall->getArg(0)->getLocStart(), + TheCall->getArg(1)->getLocEnd()); + return ExprError(); + } + + numElements = LHSType->getAs<VectorType>()->getNumElements(); + unsigned numResElements = TheCall->getNumArgs() - 2; + + // Check to see if we have a call with 2 vector arguments, the unary shuffle + // with mask. If so, verify that RHS is an integer vector type with the + // same number of elts as lhs. + if (TheCall->getNumArgs() == 2) { + if (!RHSType->hasIntegerRepresentation() || + RHSType->getAs<VectorType>()->getNumElements() != numElements) + Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector) + << SourceRange(TheCall->getArg(1)->getLocStart(), + TheCall->getArg(1)->getLocEnd()); + numResElements = numElements; + } + else if (!Context.hasSameUnqualifiedType(LHSType, RHSType)) { + Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector) + << SourceRange(TheCall->getArg(0)->getLocStart(), + TheCall->getArg(1)->getLocEnd()); + return ExprError(); + } else if (numElements != numResElements) { + QualType eltType = LHSType->getAs<VectorType>()->getElementType(); + resType = Context.getVectorType(eltType, numResElements, + VectorType::GenericVector); + } + } + + for (unsigned i = 2; i < TheCall->getNumArgs(); i++) { + if (TheCall->getArg(i)->isTypeDependent() || + TheCall->getArg(i)->isValueDependent()) + continue; + + llvm::APSInt Result(32); + if (!TheCall->getArg(i)->isIntegerConstantExpr(Result, Context)) + return ExprError(Diag(TheCall->getLocStart(), + diag::err_shufflevector_nonconstant_argument) + << TheCall->getArg(i)->getSourceRange()); + + 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(), resType, + 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, + bool isPrintf) { + tryAgain: + if (E->isTypeDependent() || E->isValueDependent()) + return false; + + switch (E->getStmtClass()) { + case Stmt::BinaryConditionalOperatorClass: + case Stmt::ConditionalOperatorClass: { + const AbstractConditionalOperator *C = cast<AbstractConditionalOperator>(E); + return SemaCheckStringLiteral(C->getTrueExpr(), TheCall, HasVAListArg, + format_idx, firstDataArg, isPrintf) + && SemaCheckStringLiteral(C->getFalseExpr(), TheCall, HasVAListArg, + format_idx, firstDataArg, isPrintf); + } + + case Stmt::IntegerLiteralClass: + // Technically -Wformat-nonliteral does not warn about this case. + // The behavior of printf and friends in this case is implementation + // dependent. Ideally if the format string cannot be null then + // it should have a 'nonnull' attribute in the function prototype. + return true; + + case Stmt::ImplicitCastExprClass: { + E = cast<ImplicitCastExpr>(E)->getSubExpr(); + goto tryAgain; + } + + case Stmt::ParenExprClass: { + E = cast<ParenExpr>(E)->getSubExpr(); + goto tryAgain; + } + + case Stmt::OpaqueValueExprClass: + if (const Expr *src = cast<OpaqueValueExpr>(E)->getSourceExpr()) { + E = src; + goto tryAgain; + } + return false; + + 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, + isPrintf); + } + + // 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, isPrintf); + } + } + } + } + + 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) { + CheckFormatString(StrE, E, TheCall, HasVAListArg, format_idx, + firstDataArg, isPrintf); + return true; + } + + return false; + } + + default: + return false; + } +} + +void +Sema::CheckNonNullArguments(const NonNullAttr *NonNull, + const CallExpr *TheCall) { + for (NonNullAttr::args_iterator i = NonNull->args_begin(), + e = NonNull->args_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(); + } +} + +/// CheckPrintfScanfArguments - Check calls to printf and scanf (and similar +/// functions) for correct use of format strings. +void +Sema::CheckPrintfScanfArguments(const CallExpr *TheCall, bool HasVAListArg, + unsigned format_idx, unsigned firstDataArg, + bool isPrintf) { + + 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)) { + const CXXMethodDecl *method_decl = + dyn_cast<CXXMethodDecl>(TheCall->getCalleeDecl()); + if (method_decl && method_decl->isInstance()) { + // Catch a format attribute mistakenly referring to the object argument. + if (format_idx == 0) + return; + --format_idx; + if(firstDataArg != 0) + --firstDataArg; + } + } + + // CHECK: printf/scanf-like function is called with no format string. + if (format_idx >= TheCall->getNumArgs()) { + Diag(TheCall->getRParenLoc(), diag::warn_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, isPrintf)) + 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_format_nonliteral_noargs) + << OrigFormatExpr->getSourceRange(); + else + Diag(TheCall->getArg(format_idx)->getLocStart(), + diag::warn_format_nonliteral) + << OrigFormatExpr->getSourceRange(); +} + +namespace { +class CheckFormatHandler : public analyze_format_string::FormatStringHandler { +protected: + 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: + CheckFormatHandler(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 HandleIncompleteSpecifier(const char *startSpecifier, + unsigned specifierLen); + + virtual void HandleInvalidPosition(const char *startSpecifier, + unsigned specifierLen, + analyze_format_string::PositionContext p); + + virtual void HandleZeroPosition(const char *startPos, unsigned posLen); + + void HandleNullChar(const char *nullCharacter); + +protected: + bool HandleInvalidConversionSpecifier(unsigned argIndex, SourceLocation Loc, + const char *startSpec, + unsigned specifierLen, + const char *csStart, unsigned csLen); + + SourceRange getFormatStringRange(); + CharSourceRange getSpecifierRange(const char *startSpecifier, + unsigned specifierLen); + SourceLocation getLocationOfByte(const char *x); + + const Expr *getDataArg(unsigned i) const; + + bool CheckNumArgs(const analyze_format_string::FormatSpecifier &FS, + const analyze_format_string::ConversionSpecifier &CS, + const char *startSpecifier, unsigned specifierLen, + unsigned argIndex); +}; +} + +SourceRange CheckFormatHandler::getFormatStringRange() { + return OrigFormatExpr->getSourceRange(); +} + +CharSourceRange CheckFormatHandler:: +getSpecifierRange(const char *startSpecifier, unsigned specifierLen) { + SourceLocation Start = getLocationOfByte(startSpecifier); + SourceLocation End = getLocationOfByte(startSpecifier + specifierLen - 1); + + // Advance the end SourceLocation by one due to half-open ranges. + End = End.getFileLocWithOffset(1); + + return CharSourceRange::getCharRange(Start, End); +} + +SourceLocation CheckFormatHandler::getLocationOfByte(const char *x) { + return S.getLocationOfStringLiteralByte(FExpr, x - Beg); +} + +void CheckFormatHandler::HandleIncompleteSpecifier(const char *startSpecifier, + unsigned specifierLen){ + SourceLocation Loc = getLocationOfByte(startSpecifier); + S.Diag(Loc, diag::warn_printf_incomplete_specifier) + << getSpecifierRange(startSpecifier, specifierLen); +} + +void +CheckFormatHandler::HandleInvalidPosition(const char *startPos, unsigned posLen, + analyze_format_string::PositionContext p) { + SourceLocation Loc = getLocationOfByte(startPos); + S.Diag(Loc, diag::warn_format_invalid_positional_specifier) + << (unsigned) p << getSpecifierRange(startPos, posLen); +} + +void CheckFormatHandler::HandleZeroPosition(const char *startPos, + unsigned posLen) { + SourceLocation Loc = getLocationOfByte(startPos); + S.Diag(Loc, diag::warn_format_zero_positional_specifier) + << getSpecifierRange(startPos, posLen); +} + +void CheckFormatHandler::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 *CheckFormatHandler::getDataArg(unsigned i) const { + return TheCall->getArg(FirstDataArg + i); +} + +void CheckFormatHandler::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(); + } + } +} + +bool +CheckFormatHandler::HandleInvalidConversionSpecifier(unsigned argIndex, + SourceLocation Loc, + const char *startSpec, + unsigned specifierLen, + const char *csStart, + unsigned csLen) { + + 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; + } + + S.Diag(Loc, diag::warn_format_invalid_conversion) + << llvm::StringRef(csStart, csLen) + << getSpecifierRange(startSpec, specifierLen); + + return keepGoing; +} + +bool +CheckFormatHandler::CheckNumArgs( + const analyze_format_string::FormatSpecifier &FS, + const analyze_format_string::ConversionSpecifier &CS, + const char *startSpecifier, unsigned specifierLen, unsigned argIndex) { + + if (argIndex >= NumDataArgs) { + if (FS.usesPositionalArg()) { + S.Diag(getLocationOfByte(CS.getStart()), + diag::warn_printf_positional_arg_exceeds_data_args) + << (argIndex+1) << NumDataArgs + << getSpecifierRange(startSpecifier, specifierLen); + } + else { + S.Diag(getLocationOfByte(CS.getStart()), + diag::warn_printf_insufficient_data_args) + << getSpecifierRange(startSpecifier, specifierLen); + } + + return false; + } + return true; +} + +//===--- CHECK: Printf format string checking ------------------------------===// + +namespace { +class CheckPrintfHandler : public CheckFormatHandler { +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) + : CheckFormatHandler(s, fexpr, origFormatExpr, firstDataArg, + numDataArgs, isObjCLiteral, beg, hasVAListArg, + theCall, formatIdx) {} + + + bool HandleInvalidPrintfConversionSpecifier( + const analyze_printf::PrintfSpecifier &FS, + const char *startSpecifier, + unsigned specifierLen); + + bool HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier &FS, + const char *startSpecifier, + unsigned specifierLen); + + bool HandleAmount(const analyze_format_string::OptionalAmount &Amt, unsigned k, + const char *startSpecifier, unsigned specifierLen); + void HandleInvalidAmount(const analyze_printf::PrintfSpecifier &FS, + const analyze_printf::OptionalAmount &Amt, + unsigned type, + const char *startSpecifier, unsigned specifierLen); + void HandleFlag(const analyze_printf::PrintfSpecifier &FS, + const analyze_printf::OptionalFlag &flag, + const char *startSpecifier, unsigned specifierLen); + void HandleIgnoredFlag(const analyze_printf::PrintfSpecifier &FS, + const analyze_printf::OptionalFlag &ignoredFlag, + const analyze_printf::OptionalFlag &flag, + const char *startSpecifier, unsigned specifierLen); +}; +} + +bool CheckPrintfHandler::HandleInvalidPrintfConversionSpecifier( + const analyze_printf::PrintfSpecifier &FS, + const char *startSpecifier, + unsigned specifierLen) { + const analyze_printf::PrintfConversionSpecifier &CS = + FS.getConversionSpecifier(); + + return HandleInvalidConversionSpecifier(FS.getArgIndex(), + getLocationOfByte(CS.getStart()), + startSpecifier, specifierLen, + CS.getStart(), CS.getLength()); +} + +bool CheckPrintfHandler::HandleAmount( + const analyze_format_string::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 << getSpecifierRange(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 + << getSpecifierRange(startSpecifier, specifierLen) + << Arg->getSourceRange(); + // Don't do any more checking. We will just emit + // spurious errors. + return false; + } + } + } + return true; +} + +void CheckPrintfHandler::HandleInvalidAmount( + const analyze_printf::PrintfSpecifier &FS, + const analyze_printf::OptionalAmount &Amt, + unsigned type, + const char *startSpecifier, + unsigned specifierLen) { + const analyze_printf::PrintfConversionSpecifier &CS = + FS.getConversionSpecifier(); + switch (Amt.getHowSpecified()) { + case analyze_printf::OptionalAmount::Constant: + S.Diag(getLocationOfByte(Amt.getStart()), + diag::warn_printf_nonsensical_optional_amount) + << type + << CS.toString() + << getSpecifierRange(startSpecifier, specifierLen) + << FixItHint::CreateRemoval(getSpecifierRange(Amt.getStart(), + Amt.getConstantLength())); + break; + + default: + S.Diag(getLocationOfByte(Amt.getStart()), + diag::warn_printf_nonsensical_optional_amount) + << type + << CS.toString() + << getSpecifierRange(startSpecifier, specifierLen); + break; + } +} + +void CheckPrintfHandler::HandleFlag(const analyze_printf::PrintfSpecifier &FS, + const analyze_printf::OptionalFlag &flag, + const char *startSpecifier, + unsigned specifierLen) { + // Warn about pointless flag with a fixit removal. + const analyze_printf::PrintfConversionSpecifier &CS = + FS.getConversionSpecifier(); + S.Diag(getLocationOfByte(flag.getPosition()), + diag::warn_printf_nonsensical_flag) + << flag.toString() << CS.toString() + << getSpecifierRange(startSpecifier, specifierLen) + << FixItHint::CreateRemoval(getSpecifierRange(flag.getPosition(), 1)); +} + +void CheckPrintfHandler::HandleIgnoredFlag( + const analyze_printf::PrintfSpecifier &FS, + const analyze_printf::OptionalFlag &ignoredFlag, + const analyze_printf::OptionalFlag &flag, + const char *startSpecifier, + unsigned specifierLen) { + // Warn about ignored flag with a fixit removal. + S.Diag(getLocationOfByte(ignoredFlag.getPosition()), + diag::warn_printf_ignored_flag) + << ignoredFlag.toString() << flag.toString() + << getSpecifierRange(startSpecifier, specifierLen) + << FixItHint::CreateRemoval(getSpecifierRange( + ignoredFlag.getPosition(), 1)); +} + +bool +CheckPrintfHandler::HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier + &FS, + const char *startSpecifier, + unsigned specifierLen) { + + using namespace analyze_format_string; + using namespace analyze_printf; + const PrintfConversionSpecifier &CS = FS.getConversionSpecifier(); + + if (FS.consumesDataArgument()) { + 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_format_mix_positional_nonpositional_args) + << getSpecifierRange(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); + } + + // FreeBSD extensions + if (CS.getKind() == ConversionSpecifier::bArg || CS.getKind() == ConversionSpecifier::DArg) { + // claim the second argument + CoveredArgs.set(argIndex + 1); + + // Now type check the data expression that matches the + // format specifier. + const Expr *Ex = getDataArg(argIndex); + const analyze_printf::ArgTypeResult &ATR = + (CS.getKind() == ConversionSpecifier::bArg) ? + ArgTypeResult(S.Context.IntTy) : ArgTypeResult::CStrTy; + if (ATR.isValid() && !ATR.matchesType(S.Context, Ex->getType())) + S.Diag(getLocationOfByte(CS.getStart()), + diag::warn_printf_conversion_argument_type_mismatch) + << ATR.getRepresentativeType(S.Context) << Ex->getType() + << getSpecifierRange(startSpecifier, specifierLen) + << Ex->getSourceRange(); + + // Now type check the data expression that matches the + // format specifier. + Ex = getDataArg(argIndex + 1); + const analyze_printf::ArgTypeResult &ATR2 = ArgTypeResult::CStrTy; + if (ATR2.isValid() && !ATR2.matchesType(S.Context, Ex->getType())) + S.Diag(getLocationOfByte(CS.getStart()), + diag::warn_printf_conversion_argument_type_mismatch) + << ATR2.getRepresentativeType(S.Context) << Ex->getType() + << getSpecifierRange(startSpecifier, specifierLen) + << Ex->getSourceRange(); + + return true; + } + // END OF FREEBSD EXTENSIONS + + // Check for using an Objective-C specific conversion specifier + // in a non-ObjC literal. + if (!IsObjCLiteral && CS.isObjCArg()) { + return HandleInvalidPrintfConversionSpecifier(FS, startSpecifier, + specifierLen); + } + + // Check for invalid use of field width + if (!FS.hasValidFieldWidth()) { + HandleInvalidAmount(FS, FS.getFieldWidth(), /* field width */ 0, + startSpecifier, specifierLen); + } + + // Check for invalid use of precision + if (!FS.hasValidPrecision()) { + HandleInvalidAmount(FS, FS.getPrecision(), /* precision */ 1, + startSpecifier, specifierLen); + } + + // Check each flag does not conflict with any other component. + if (!FS.hasValidThousandsGroupingPrefix()) + HandleFlag(FS, FS.hasThousandsGrouping(), startSpecifier, specifierLen); + if (!FS.hasValidLeadingZeros()) + HandleFlag(FS, FS.hasLeadingZeros(), startSpecifier, specifierLen); + if (!FS.hasValidPlusPrefix()) + HandleFlag(FS, FS.hasPlusPrefix(), startSpecifier, specifierLen); + if (!FS.hasValidSpacePrefix()) + HandleFlag(FS, FS.hasSpacePrefix(), startSpecifier, specifierLen); + if (!FS.hasValidAlternativeForm()) + HandleFlag(FS, FS.hasAlternativeForm(), startSpecifier, specifierLen); + if (!FS.hasValidLeftJustified()) + HandleFlag(FS, FS.isLeftJustified(), startSpecifier, specifierLen); + + // Check that flags are not ignored by another flag + if (FS.hasSpacePrefix() && FS.hasPlusPrefix()) // ' ' ignored by '+' + HandleIgnoredFlag(FS, FS.hasSpacePrefix(), FS.hasPlusPrefix(), + startSpecifier, specifierLen); + if (FS.hasLeadingZeros() && FS.isLeftJustified()) // '0' ignored by '-' + HandleIgnoredFlag(FS, FS.hasLeadingZeros(), FS.isLeftJustified(), + startSpecifier, specifierLen); + + // Check the length modifier is valid with the given conversion specifier. + const LengthModifier &LM = FS.getLengthModifier(); + if (!FS.hasValidLengthModifier()) + S.Diag(getLocationOfByte(LM.getStart()), + diag::warn_format_nonsensical_length) + << LM.toString() << CS.toString() + << getSpecifierRange(startSpecifier, specifierLen) + << FixItHint::CreateRemoval(getSpecifierRange(LM.getStart(), + LM.getLength())); + + // Are we using '%n'? + if (CS.getKind() == ConversionSpecifier::nArg) { + // Issue a warning about this being a possible security issue. + S.Diag(getLocationOfByte(CS.getStart()), diag::warn_printf_write_back) + << getSpecifierRange(startSpecifier, specifierLen); + // Continue checking the other format specifiers. + return true; + } + + // The remaining checks depend on the data arguments. + if (HasVAListArg) + return true; + + if (!CheckNumArgs(FS, CS, startSpecifier, specifierLen, argIndex)) + 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) { + // All further checking is done on the subexpression. + Ex = ICE->getSubExpr(); + if (ATR.matchesType(S.Context, Ex->getType())) + return true; + } + + // We may be able to offer a FixItHint if it is a supported type. + PrintfSpecifier fixedFS = FS; + bool success = fixedFS.fixType(Ex->getType()); + + if (success) { + // Get the fix string from the fixed format specifier + llvm::SmallString<128> buf; + llvm::raw_svector_ostream os(buf); + fixedFS.toString(os); + + // FIXME: getRepresentativeType() perhaps should return a string + // instead of a QualType to better handle when the representative + // type is 'wint_t' (which is defined in the system headers). + S.Diag(getLocationOfByte(CS.getStart()), + diag::warn_printf_conversion_argument_type_mismatch) + << ATR.getRepresentativeType(S.Context) << Ex->getType() + << getSpecifierRange(startSpecifier, specifierLen) + << Ex->getSourceRange() + << FixItHint::CreateReplacement( + getSpecifierRange(startSpecifier, specifierLen), + os.str()); + } + else { + S.Diag(getLocationOfByte(CS.getStart()), + diag::warn_printf_conversion_argument_type_mismatch) + << ATR.getRepresentativeType(S.Context) << Ex->getType() + << getSpecifierRange(startSpecifier, specifierLen) + << Ex->getSourceRange(); + } + } + + return true; +} + +//===--- CHECK: Scanf format string checking ------------------------------===// + +namespace { +class CheckScanfHandler : public CheckFormatHandler { +public: + CheckScanfHandler(Sema &s, const StringLiteral *fexpr, + const Expr *origFormatExpr, unsigned firstDataArg, + unsigned numDataArgs, bool isObjCLiteral, + const char *beg, bool hasVAListArg, + const CallExpr *theCall, unsigned formatIdx) + : CheckFormatHandler(s, fexpr, origFormatExpr, firstDataArg, + numDataArgs, isObjCLiteral, beg, hasVAListArg, + theCall, formatIdx) {} + + bool HandleScanfSpecifier(const analyze_scanf::ScanfSpecifier &FS, + const char *startSpecifier, + unsigned specifierLen); + + bool HandleInvalidScanfConversionSpecifier( + const analyze_scanf::ScanfSpecifier &FS, + const char *startSpecifier, + unsigned specifierLen); + + void HandleIncompleteScanList(const char *start, const char *end); +}; +} + +void CheckScanfHandler::HandleIncompleteScanList(const char *start, + const char *end) { + S.Diag(getLocationOfByte(end), diag::warn_scanf_scanlist_incomplete) + << getSpecifierRange(start, end - start); +} + +bool CheckScanfHandler::HandleInvalidScanfConversionSpecifier( + const analyze_scanf::ScanfSpecifier &FS, + const char *startSpecifier, + unsigned specifierLen) { + + const analyze_scanf::ScanfConversionSpecifier &CS = + FS.getConversionSpecifier(); + + return HandleInvalidConversionSpecifier(FS.getArgIndex(), + getLocationOfByte(CS.getStart()), + startSpecifier, specifierLen, + CS.getStart(), CS.getLength()); +} + +bool CheckScanfHandler::HandleScanfSpecifier( + const analyze_scanf::ScanfSpecifier &FS, + const char *startSpecifier, + unsigned specifierLen) { + + using namespace analyze_scanf; + using namespace analyze_format_string; + + const ScanfConversionSpecifier &CS = FS.getConversionSpecifier(); + + // Handle case where '%' and '*' don't consume an argument. These shouldn't + // be used to decide if we are using positional arguments consistently. + if (FS.consumesDataArgument()) { + 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_format_mix_positional_nonpositional_args) + << getSpecifierRange(startSpecifier, specifierLen); + return false; + } + } + + // Check if the field with is non-zero. + const OptionalAmount &Amt = FS.getFieldWidth(); + if (Amt.getHowSpecified() == OptionalAmount::Constant) { + if (Amt.getConstantAmount() == 0) { + const CharSourceRange &R = getSpecifierRange(Amt.getStart(), + Amt.getConstantLength()); + S.Diag(getLocationOfByte(Amt.getStart()), + diag::warn_scanf_nonzero_width) + << R << FixItHint::CreateRemoval(R); + } + } + + if (!FS.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 the length modifier is valid with the given conversion specifier. + const LengthModifier &LM = FS.getLengthModifier(); + if (!FS.hasValidLengthModifier()) { + S.Diag(getLocationOfByte(LM.getStart()), + diag::warn_format_nonsensical_length) + << LM.toString() << CS.toString() + << getSpecifierRange(startSpecifier, specifierLen) + << FixItHint::CreateRemoval(getSpecifierRange(LM.getStart(), + LM.getLength())); + } + + // The remaining checks depend on the data arguments. + if (HasVAListArg) + return true; + + if (!CheckNumArgs(FS, CS, startSpecifier, specifierLen, argIndex)) + return false; + + // FIXME: Check that the argument type matches the format specifier. + + return true; +} + +void Sema::CheckFormatString(const StringLiteral *FExpr, + const Expr *OrigFormatExpr, + const CallExpr *TheCall, bool HasVAListArg, + unsigned format_idx, unsigned firstDataArg, + bool isPrintf) { + + // CHECK: is the format string a wide literal? + if (FExpr->isWide()) { + Diag(FExpr->getLocStart(), + diag::warn_format_string_is_wide_literal) + << OrigFormatExpr->getSourceRange(); + return; + } + + // Str - The format string. NOTE: this is NOT null-terminated! + llvm::StringRef StrRef = FExpr->getString(); + const char *Str = StrRef.data(); + unsigned StrLen = StrRef.size(); + + // CHECK: empty format string? + if (StrLen == 0) { + Diag(FExpr->getLocStart(), diag::warn_empty_format_string) + << OrigFormatExpr->getSourceRange(); + return; + } + + if (isPrintf) { + CheckPrintfHandler H(*this, FExpr, OrigFormatExpr, firstDataArg, + TheCall->getNumArgs() - firstDataArg, + isa<ObjCStringLiteral>(OrigFormatExpr), Str, + HasVAListArg, TheCall, format_idx); + + bool FormatExtensions = getLangOptions().FormatExtensions; + if (!analyze_format_string::ParsePrintfString(H, Str, Str + StrLen, + FormatExtensions)) + H.DoneProcessing(); + } + else { + CheckScanfHandler H(*this, FExpr, OrigFormatExpr, firstDataArg, + TheCall->getNumArgs() - firstDataArg, + isa<ObjCStringLiteral>(OrigFormatExpr), Str, + HasVAListArg, TheCall, format_idx); + + if (!analyze_format_string::ParseScanfString(H, Str, Str + StrLen)) + H.DoneProcessing(); + } +} + +//===--- CHECK: Return Address of Stack Variable --------------------------===// + +static Expr *EvalVal(Expr *E, llvm::SmallVectorImpl<DeclRefExpr *> &refVars); +static Expr *EvalAddr(Expr* E, llvm::SmallVectorImpl<DeclRefExpr *> &refVars); + +/// CheckReturnStackAddr - Check if a return statement returns the address +/// of a stack variable. +void +Sema::CheckReturnStackAddr(Expr *RetValExp, QualType lhsType, + SourceLocation ReturnLoc) { + + Expr *stackE = 0; + llvm::SmallVector<DeclRefExpr *, 8> refVars; + + // Perform checking for returned stack addresses, local blocks, + // label addresses or references to temporaries. + if (lhsType->isPointerType() || lhsType->isBlockPointerType()) { + stackE = EvalAddr(RetValExp, refVars); + } else if (lhsType->isReferenceType()) { + stackE = EvalVal(RetValExp, refVars); + } + + if (stackE == 0) + return; // Nothing suspicious was found. + + SourceLocation diagLoc; + SourceRange diagRange; + if (refVars.empty()) { + diagLoc = stackE->getLocStart(); + diagRange = stackE->getSourceRange(); + } else { + // We followed through a reference variable. 'stackE' contains the + // problematic expression but we will warn at the return statement pointing + // at the reference variable. We will later display the "trail" of + // reference variables using notes. + diagLoc = refVars[0]->getLocStart(); + diagRange = refVars[0]->getSourceRange(); + } + + if (DeclRefExpr *DR = dyn_cast<DeclRefExpr>(stackE)) { //address of local var. + Diag(diagLoc, lhsType->isReferenceType() ? diag::warn_ret_stack_ref + : diag::warn_ret_stack_addr) + << DR->getDecl()->getDeclName() << diagRange; + } else if (isa<BlockExpr>(stackE)) { // local block. + Diag(diagLoc, diag::err_ret_local_block) << diagRange; + } else if (isa<AddrLabelExpr>(stackE)) { // address of label. + Diag(diagLoc, diag::warn_ret_addr_label) << diagRange; + } else { // local temporary. + Diag(diagLoc, lhsType->isReferenceType() ? diag::warn_ret_local_temp_ref + : diag::warn_ret_local_temp_addr) + << diagRange; + } + + // Display the "trail" of reference variables that we followed until we + // found the problematic expression using notes. + for (unsigned i = 0, e = refVars.size(); i != e; ++i) { + VarDecl *VD = cast<VarDecl>(refVars[i]->getDecl()); + // If this var binds to another reference var, show the range of the next + // var, otherwise the var binds to the problematic expression, in which case + // show the range of the expression. + SourceRange range = (i < e-1) ? refVars[i+1]->getSourceRange() + : stackE->getSourceRange(); + Diag(VD->getLocation(), diag::note_ref_var_local_bind) + << VD->getDeclName() << range; + } +} + +/// 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, a local block, an address of a label, or a +/// reference to local temporary. 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 one of the +/// above problematic expressions (2) is something we cannot determine leads to +/// a problematic expression based on such local checking. +/// +/// Both EvalAddr and EvalVal follow through reference variables to evaluate +/// the expression that they point to. Such variables are added to the +/// 'refVars' vector so that we know what the reference variable "trail" was. +/// +/// 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 the above problematic +/// expressions. +/// +/// 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 Expr *EvalAddr(Expr *E, llvm::SmallVectorImpl<DeclRefExpr *> &refVars) { + if (E->isTypeDependent()) + return NULL; + + // 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(), refVars); + + case Stmt::DeclRefExprClass: { + DeclRefExpr *DR = cast<DeclRefExpr>(E); + + if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl())) + // If this is a reference variable, follow through to the expression that + // it points to. + if (V->hasLocalStorage() && + V->getType()->isReferenceType() && V->hasInit()) { + // Add the reference variable to the "trail". + refVars.push_back(DR); + return EvalAddr(V->getInit(), refVars); + } + + return NULL; + } + + 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() == UO_AddrOf) + return EvalVal(U->getSubExpr(), refVars); + else + return NULL; + } + + case Stmt::BinaryOperatorClass: { + // Handle pointer arithmetic. All other binary operators are not valid + // in this context. + BinaryOperator *B = cast<BinaryOperator>(E); + BinaryOperatorKind op = B->getOpcode(); + + if (op != BO_Add && op != BO_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, refVars); + } + + // 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()) { + // In C++, we can have a throw-expression, which has 'void' type. + if (!lhsExpr->getType()->isVoidType()) + if (Expr* LHS = EvalAddr(lhsExpr, refVars)) + return LHS; + } + + // In C++, we can have a throw-expression, which has 'void' type. + if (C->getRHS()->getType()->isVoidType()) + return NULL; + + return EvalAddr(C->getRHS(), refVars); + } + + case Stmt::BlockExprClass: + if (cast<BlockExpr>(E)->getBlockDecl()->hasCaptures()) + return E; // local block. + return NULL; + + case Stmt::AddrLabelExprClass: + return E; // address of label. + + // 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, refVars); + else if (T->isArrayType()) + return EvalVal(SubExpr, refVars); + 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, refVars); + 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 Expr *EvalVal(Expr *E, llvm::SmallVectorImpl<DeclRefExpr *> &refVars) { +do { + // 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::ImplicitCastExprClass: { + ImplicitCastExpr *IE = cast<ImplicitCastExpr>(E); + if (IE->getValueKind() == VK_LValue) { + E = IE->getSubExpr(); + continue; + } + return NULL; + } + + case Stmt::DeclRefExprClass: { + // When we hit a DeclRefExpr we are looking at code that refers to a + // variable's name. If it's not a reference variable 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()) { + if (!V->getType()->isReferenceType()) + return DR; + + // Reference variable, follow through to the expression that + // it points to. + if (V->hasInit()) { + // Add the reference variable to the "trail". + refVars.push_back(DR); + return EvalVal(V->getInit(), refVars); + } + } + + return NULL; + } + + case Stmt::ParenExprClass: { + // Ignore parentheses. + E = cast<ParenExpr>(E)->getSubExpr(); + continue; + } + + 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() == UO_Deref) + return EvalAddr(U->getSubExpr(), refVars); + + 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(), refVars); + } + + case Stmt::ConditionalOperatorClass: { + // For conditional operators we need to see if either the LHS or RHS are + // non-NULL Expr'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 (Expr *LHS = EvalVal(lhsExpr, refVars)) + return LHS; + + return EvalVal(C->getRHS(), refVars); + } + + // 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 NULL; + + // Check whether the member type is itself a reference, in which case + // we're not going to refer to the member, but to what the member refers to. + if (M->getMemberDecl()->getType()->isReferenceType()) + return NULL; + + return EvalVal(M->getBase(), refVars); + } + + default: + // Check that we don't return or take the address of a reference to a + // temporary. This is only useful in C++. + if (!E->isTypeDependent() && E->isRValue()) + return E; + + // Everything else: we simply don't reason about them. + return NULL; + } +} while (true); +} + +//===--- 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->IgnoreParenImpCasts(); + Expr* RightExprSansParen = rex->IgnoreParenImpCasts(); + + // 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(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 opaque value of the given integral type. + static IntRange forValueOfType(ASTContext &C, QualType T) { + return forValueOfCanonicalType(C, + T->getCanonicalTypeInternal().getTypePtr()); + } + + /// Returns the range of an opaque value of a canonical integral type. + static IntRange forValueOfCanonicalType(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(); + + // For enum types, use the known bit width of the enumerators. + if (const EnumType *ET = dyn_cast<EnumType>(T)) { + EnumDecl *Enum = ET->getDecl(); + if (!Enum->isDefinition()) + return IntRange(C.getIntWidth(QualType(T, 0)), false); + + 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 "target" range of a canonical integral type, i.e. + /// the range of values expressible in the type. + /// + /// This matches forValueOfCanonicalType except that enums have the + /// full range of their type, not the range of their enumerators. + static IntRange forTargetOfCanonicalType(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)) + T = ET->getDecl()->getIntegerType().getTypePtr(); + + 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 = 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() == CK_NoOp) + return GetExprRange(C, CE->getSubExpr(), MaxWidth); + + IntRange OutputTypeRange = IntRange::forValueOfType(C, CE->getType()); + + bool isIntegerCast = (CE->getCastKind() == CK_IntegralCast); + + // 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 BO_LAnd: + case BO_LOr: + case BO_LT: + case BO_GT: + case BO_LE: + case BO_GE: + case BO_EQ: + case BO_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 BO_MulAssign: + case BO_DivAssign: + case BO_RemAssign: + case BO_AddAssign: + case BO_SubAssign: + return IntRange::forValueOfType(C, E->getType()); + + // Operations with opaque sources are black-listed. + case BO_PtrMemD: + case BO_PtrMemI: + return IntRange::forValueOfType(C, E->getType()); + + // Bitwise-and uses the *infinum* of the two source ranges. + case BO_And: + case BO_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 BO_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::forValueOfType(C, E->getType()); + return IntRange(R.Width, /*NonNegative*/ true); + } + } + // fallthrough + + case BO_ShlAssign: + return IntRange::forValueOfType(C, E->getType()); + + // Right shift by a constant can narrow its left argument. + case BO_Shr: + case BO_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 BO_Comma: + return GetExprRange(C, BO->getRHS(), MaxWidth); + + // Black-list pointer subtractions. + case BO_Sub: + if (BO->getLHS()->getType()->isPointerType()) + return IntRange::forValueOfType(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 UO_LNot: + return IntRange::forBoolType(); + + // Operations with opaque sources are black-listed. + case UO_Deref: + case UO_AddrOf: // should be impossible + return IntRange::forValueOfType(C, E->getType()); + + default: + return GetExprRange(C, UO->getSubExpr(), MaxWidth); + } + } + + if (dyn_cast<OffsetOfExpr>(E)) { + IntRange::forValueOfType(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::forValueOfType(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, SourceLocation CC); + +static bool IsZero(Sema &S, Expr *E) { + // Suppress cases where we are comparing against an enum constant. + if (const DeclRefExpr *DR = + dyn_cast<DeclRefExpr>(E->IgnoreParenImpCasts())) + if (isa<EnumConstantDecl>(DR->getDecl())) + return false; + + // Suppress cases where the '0' value is expanded from a macro. + if (E->getLocStart().isMacroID()) + return false; + + llvm::APSInt Value; + return E->isIntegerConstantExpr(Value, S.Context) && Value == 0; +} + +static bool HasEnumType(Expr *E) { + // Strip off implicit integral promotions. + while (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(E)) { + if (ICE->getCastKind() != CK_IntegralCast && + ICE->getCastKind() != CK_NoOp) + break; + E = ICE->getSubExpr(); + } + + return E->getType()->isEnumeralType(); +} + +void CheckTrivialUnsignedComparison(Sema &S, BinaryOperator *E) { + BinaryOperatorKind op = E->getOpcode(); + if (E->isValueDependent()) + return; + + if (op == BO_LT && IsZero(S, E->getRHS())) { + S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison) + << "< 0" << "false" << HasEnumType(E->getLHS()) + << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); + } else if (op == BO_GE && IsZero(S, E->getRHS())) { + S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison) + << ">= 0" << "true" << HasEnumType(E->getLHS()) + << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); + } else if (op == BO_GT && IsZero(S, E->getLHS())) { + S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison) + << "0 >" << "false" << HasEnumType(E->getRHS()) + << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange(); + } else if (op == BO_LE && IsZero(S, E->getLHS())) { + S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison) + << "0 <=" << "true" << HasEnumType(E->getRHS()) + << 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(), E->getOperatorLoc()); + AnalyzeImplicitConversions(S, E->getRHS(), E->getOperatorLoc()); +} + +/// \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. + // + // We also don't care about value-dependent expressions or expressions + // whose result is a constant. + if (!T->hasUnsignedIntegerRepresentation() + || E->isValueDependent() || E->isIntegerConstantExpr(S.Context)) + 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()->hasSignedIntegerRepresentation()) { + assert(!rex->getType()->hasSignedIntegerRepresentation() && + "unsigned comparison between two signed integer expressions?"); + signedOperand = lex; + unsignedOperand = rex; + } else if (rex->getType()->hasSignedIntegerRepresentation()) { + 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, E->getOperatorLoc()); + AnalyzeImplicitConversions(S, rex, E->getOperatorLoc()); + + // 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(); +} + +/// Analyzes an attempt to assign the given value to a bitfield. +/// +/// Returns true if there was something fishy about the attempt. +bool AnalyzeBitFieldAssignment(Sema &S, FieldDecl *Bitfield, Expr *Init, + SourceLocation InitLoc) { + assert(Bitfield->isBitField()); + if (Bitfield->isInvalidDecl()) + return false; + + // White-list bool bitfields. + if (Bitfield->getType()->isBooleanType()) + return false; + + // Ignore value- or type-dependent expressions. + if (Bitfield->getBitWidth()->isValueDependent() || + Bitfield->getBitWidth()->isTypeDependent() || + Init->isValueDependent() || + Init->isTypeDependent()) + return false; + + Expr *OriginalInit = Init->IgnoreParenImpCasts(); + + llvm::APSInt Width(32); + Expr::EvalResult InitValue; + if (!Bitfield->getBitWidth()->isIntegerConstantExpr(Width, S.Context) || + !OriginalInit->Evaluate(InitValue, S.Context) || + !InitValue.Val.isInt()) + return false; + + const llvm::APSInt &Value = InitValue.Val.getInt(); + unsigned OriginalWidth = Value.getBitWidth(); + unsigned FieldWidth = Width.getZExtValue(); + + if (OriginalWidth <= FieldWidth) + return false; + + llvm::APSInt TruncatedValue = Value.trunc(FieldWidth); + + // It's fairly common to write values into signed bitfields + // that, if sign-extended, would end up becoming a different + // value. We don't want to warn about that. + if (Value.isSigned() && Value.isNegative()) + TruncatedValue = TruncatedValue.sext(OriginalWidth); + else + TruncatedValue = TruncatedValue.zext(OriginalWidth); + + if (Value == TruncatedValue) + return false; + + std::string PrettyValue = Value.toString(10); + std::string PrettyTrunc = TruncatedValue.toString(10); + + S.Diag(InitLoc, diag::warn_impcast_bitfield_precision_constant) + << PrettyValue << PrettyTrunc << OriginalInit->getType() + << Init->getSourceRange(); + + return true; +} + +/// Analyze the given simple or compound assignment for warning-worthy +/// operations. +void AnalyzeAssignment(Sema &S, BinaryOperator *E) { + // Just recurse on the LHS. + AnalyzeImplicitConversions(S, E->getLHS(), E->getOperatorLoc()); + + // We want to recurse on the RHS as normal unless we're assigning to + // a bitfield. + if (FieldDecl *Bitfield = E->getLHS()->getBitField()) { + if (AnalyzeBitFieldAssignment(S, Bitfield, E->getRHS(), + E->getOperatorLoc())) { + // Recurse, ignoring any implicit conversions on the RHS. + return AnalyzeImplicitConversions(S, E->getRHS()->IgnoreParenImpCasts(), + E->getOperatorLoc()); + } + } + + AnalyzeImplicitConversions(S, E->getRHS(), E->getOperatorLoc()); +} + +/// Diagnose an implicit cast; purely a helper for CheckImplicitConversion. +void DiagnoseImpCast(Sema &S, Expr *E, QualType T, SourceLocation CContext, + unsigned diag) { + S.Diag(E->getExprLoc(), diag) + << E->getType() << T << E->getSourceRange() << SourceRange(CContext); +} + +std::string PrettyPrintInRange(const llvm::APSInt &Value, IntRange Range) { + if (!Range.Width) return "0"; + + llvm::APSInt ValueInRange = Value; + ValueInRange.setIsSigned(!Range.NonNegative); + ValueInRange = ValueInRange.trunc(Range.Width); + return ValueInRange.toString(10); +} + +void CheckImplicitConversion(Sema &S, Expr *E, QualType T, + SourceLocation CC, 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; + + // If the conversion context location is invalid or instantiated + // from a system macro, don't complain. + if (CC.isInvalid() || + (CC.isMacroID() && S.Context.getSourceManager().isInSystemHeader( + S.Context.getSourceManager().getSpellingLoc(CC)))) + 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, CC, 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, CC, 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, CC, diag::warn_impcast_float_precision); + } + return; + } + + // If the target is integral, always warn. + if ((TargetBT && TargetBT->isInteger())) { + Expr *InnerE = E->IgnoreParenImpCasts(); + if (FloatingLiteral *LiteralExpr = dyn_cast<FloatingLiteral>(InnerE)) { + DiagnoseImpCast(S, LiteralExpr, T, CC, + diag::warn_impcast_literal_float_to_integer); + } else { + DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_float_integer); + } + } + + return; + } + + if (!Source->isIntegerType() || !Target->isIntegerType()) + return; + + IntRange SourceRange = GetExprRange(S.Context, E); + IntRange TargetRange = IntRange::forTargetOfCanonicalType(S.Context, Target); + + if (SourceRange.Width > TargetRange.Width) { + // If the source is a constant, use a default-on diagnostic. + // TODO: this should happen for bitfield stores, too. + llvm::APSInt Value(32); + if (E->isIntegerConstantExpr(Value, S.Context)) { + std::string PrettySourceValue = Value.toString(10); + std::string PrettyTargetValue = PrettyPrintInRange(Value, TargetRange); + + S.Diag(E->getExprLoc(), diag::warn_impcast_integer_precision_constant) + << PrettySourceValue << PrettyTargetValue + << E->getType() << T << E->getSourceRange() << clang::SourceRange(CC); + return; + } + + // 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, CC, diag::warn_impcast_integer_64_32); + return DiagnoseImpCast(S, E, T, CC, 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, CC, DiagID); + } + + return; +} + +void CheckConditionalOperator(Sema &S, ConditionalOperator *E, QualType T); + +void CheckConditionalOperand(Sema &S, Expr *E, QualType T, + SourceLocation CC, bool &ICContext) { + E = E->IgnoreParenImpCasts(); + + if (isa<ConditionalOperator>(E)) + return CheckConditionalOperator(S, cast<ConditionalOperator>(E), T); + + AnalyzeImplicitConversions(S, E, CC); + if (E->getType() != T) + return CheckImplicitConversion(S, E, T, CC, &ICContext); + return; +} + +void CheckConditionalOperator(Sema &S, ConditionalOperator *E, QualType T) { + SourceLocation CC = E->getQuestionLoc(); + + AnalyzeImplicitConversions(S, E->getCond(), CC); + + bool Suspicious = false; + CheckConditionalOperand(S, E->getTrueExpr(), T, CC, Suspicious); + CheckConditionalOperand(S, E->getFalseExpr(), T, CC, 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, + CC)) + return; + + // ...and -Wsign-compare isn't... + if (!S.Diags.getDiagnosticLevel(diag::warn_mixed_sign_conditional, CC)) + 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(), CC, &Suspicious); + if (!Suspicious) + CheckImplicitConversion(S, E->getFalseExpr()->IgnoreParenImpCasts(), + E->getType(), CC, &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, SourceLocation CC) { + 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, CC); + + // Now continue drilling into this expression. + + // Skip past explicit casts. + if (isa<ExplicitCastExpr>(E)) { + E = cast<ExplicitCastExpr>(E)->getSubExpr()->IgnoreParenImpCasts(); + return AnalyzeImplicitConversions(S, E, CC); + } + + if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) { + // Do a somewhat different check with comparison operators. + if (BO->isComparisonOp()) + return AnalyzeComparison(S, BO); + + // And with assignments and compound assignments. + if (BO->isAssignmentOp()) + return AnalyzeAssignment(S, BO); + } + + // 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. + CC = E->getExprLoc(); + for (Stmt::child_range I = E->children(); I; ++I) + AnalyzeImplicitConversions(S, cast<Expr>(*I), CC); +} + +} // end anonymous namespace + +/// Diagnoses "dangerous" implicit conversions within the given +/// expression (which is a full expression). Implements -Wconversion +/// and -Wsign-compare. +/// +/// \param CC the "context" location of the implicit conversion, i.e. +/// the most location of the syntactic entity requiring the implicit +/// conversion +void Sema::CheckImplicitConversions(Expr *E, SourceLocation CC) { + // 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; + + // This is not the right CC for (e.g.) a variable initialization. + AnalyzeImplicitConversions(*this, E, CC); +} + +void Sema::CheckBitFieldInitialization(SourceLocation InitLoc, + FieldDecl *BitField, + Expr *Init) { + (void) AnalyzeBitFieldAssignment(*this, BitField, Init, InitLoc); +} + +/// 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(ParmVarDecl **P, ParmVarDecl **PEnd, + bool CheckParameterNames) { + bool HasInvalidParm = false; + for (; P != PEnd; ++P) { + ParmVarDecl *Param = *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 (CheckParameterNames && + 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; +} + +/// CheckCastAlign - Implements -Wcast-align, which warns when a +/// pointer cast increases the alignment requirements. +void Sema::CheckCastAlign(Expr *Op, QualType T, SourceRange TRange) { + // This is actually a lot of work to potentially be doing on every + // cast; don't do it if we're ignoring -Wcast_align (as is the default). + if (getDiagnostics().getDiagnosticLevel(diag::warn_cast_align, + TRange.getBegin()) + == Diagnostic::Ignored) + return; + + // Ignore dependent types. + if (T->isDependentType() || Op->getType()->isDependentType()) + return; + + // Require that the destination be a pointer type. + const PointerType *DestPtr = T->getAs<PointerType>(); + if (!DestPtr) return; + + // If the destination has alignment 1, we're done. + QualType DestPointee = DestPtr->getPointeeType(); + if (DestPointee->isIncompleteType()) return; + CharUnits DestAlign = Context.getTypeAlignInChars(DestPointee); + if (DestAlign.isOne()) return; + + // Require that the source be a pointer type. + const PointerType *SrcPtr = Op->getType()->getAs<PointerType>(); + if (!SrcPtr) return; + QualType SrcPointee = SrcPtr->getPointeeType(); + + // Whitelist casts from cv void*. We already implicitly + // whitelisted casts to cv void*, since they have alignment 1. + // Also whitelist casts involving incomplete types, which implicitly + // includes 'void'. + if (SrcPointee->isIncompleteType()) return; + + CharUnits SrcAlign = Context.getTypeAlignInChars(SrcPointee); + if (SrcAlign >= DestAlign) return; + + Diag(TRange.getBegin(), diag::warn_cast_align) + << Op->getType() << T + << static_cast<unsigned>(SrcAlign.getQuantity()) + << static_cast<unsigned>(DestAlign.getQuantity()) + << TRange << Op->getSourceRange(); +} + +void Sema::CheckArrayAccess(const clang::ArraySubscriptExpr *E) { + const Expr *BaseExpr = E->getBase()->IgnoreParenImpCasts(); + const ConstantArrayType *ArrayTy = + Context.getAsConstantArrayType(BaseExpr->getType()); + if (!ArrayTy) + return; + + const Expr *IndexExpr = E->getIdx(); + if (IndexExpr->isValueDependent()) + return; + llvm::APSInt index; + if (!IndexExpr->isIntegerConstantExpr(index, Context)) + return; + + if (!index.isNegative()) { + llvm::APInt size = ArrayTy->getSize(); + if (!size.isStrictlyPositive()) + return; + if (size.getBitWidth() > index.getBitWidth()) + index = index.sext(size.getBitWidth()); + else if (size.getBitWidth() < index.getBitWidth()) + size = size.sext(index.getBitWidth()); + + if (index.slt(size)) + return; + + Diag(E->getBase()->getLocStart(), diag::warn_array_index_exceeds_bounds) + << index.toString(10, true) << size.toString(10, true) + << IndexExpr->getSourceRange(); + } else { + Diag(E->getBase()->getLocStart(), diag::warn_array_index_precedes_bounds) + << index.toString(10, true) << IndexExpr->getSourceRange(); + } + + const NamedDecl *ND = NULL; + if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(BaseExpr)) + ND = dyn_cast<NamedDecl>(DRE->getDecl()); + if (const MemberExpr *ME = dyn_cast<MemberExpr>(BaseExpr)) + ND = dyn_cast<NamedDecl>(ME->getMemberDecl()); + if (ND) + Diag(ND->getLocStart(), diag::note_array_index_out_of_bounds) + << ND->getDeclName(); +} + |
