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llvm / clang / refs/heads/release_29 / . / lib / Sema / SemaChecking.cpp
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//===--- 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;
}
/// Checks that a call expression's argument count is the desired number.
/// This is useful when doing custom type-checking. Returns true on error.
static bool checkArgCount(Sema &S, CallExpr *call, unsigned desiredArgCount) {
unsigned argCount = call->getNumArgs();
if (argCount == desiredArgCount) return false;
if (argCount < desiredArgCount)
return S.Diag(call->getLocEnd(), diag::err_typecheck_call_too_few_args)
<< 0 /*function call*/ << desiredArgCount << argCount
<< call->getSourceRange();
// Highlight all the excess arguments.
SourceRange range(call->getArg(desiredArgCount)->getLocStart(),
call->getArg(argCount - 1)->getLocEnd());
return S.Diag(range.getBegin(), diag::err_typecheck_call_too_many_args)
<< 0 /*function call*/ << desiredArgCount << argCount
<< call->getArg(1)->getSourceRange();
}
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_classify_type:
if (checkArgCount(*this, TheCall, 1)) return true;
TheCall->setType(Context.IntTy);
break;
case Builtin::BI__builtin_constant_p:
if (checkArgCount(*this, TheCall, 1)) return true;
TheCall->setType(Context.IntTy);
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", recursively.
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::PredefinedExprClass:
// While __func__, etc., are technically not string literals, they
// cannot contain format specifiers and thus are not a security
// liability.
return true;
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);
}
// 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);
if (!analyze_format_string::ParsePrintfString(H, Str, Str + StrLen))
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);
}
// Diagnose conversions between different enumeration types.
if (const EnumType *SourceEnum = Source->getAs<EnumType>())
if (const EnumType *TargetEnum = Target->getAs<EnumType>())
if ((SourceEnum->getDecl()->getIdentifier() ||
SourceEnum->getDecl()->getTypedefForAnonDecl()) &&
(TargetEnum->getDecl()->getIdentifier() ||
TargetEnum->getDecl()->getTypedefForAnonDecl()) &&
SourceEnum != TargetEnum)
return DiagnoseImpCast(S, E, T, CC,
diag::warn_impcast_different_enum_types);
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();
}
static void CheckArrayAccess_Check(Sema &S,
const clang::ArraySubscriptExpr *E) {
const Expr *BaseExpr = E->getBase()->IgnoreParenImpCasts();
const ConstantArrayType *ArrayTy =
S.Context.getAsConstantArrayType(BaseExpr->getType());
if (!ArrayTy)
return;
const Expr *IndexExpr = E->getIdx();
if (IndexExpr->isValueDependent())
return;
llvm::APSInt index;
if (!IndexExpr->isIntegerConstantExpr(index, S.Context))
return;
if (index.isUnsigned() || !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;
S.DiagRuntimeBehavior(E->getBase()->getLocStart(), BaseExpr,
S.PDiag(diag::warn_array_index_exceeds_bounds)
<< index.toString(10, true)
<< size.toString(10, true)
<< IndexExpr->getSourceRange());
} else {
S.DiagRuntimeBehavior(E->getBase()->getLocStart(), BaseExpr,
S.PDiag(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)
S.DiagRuntimeBehavior(ND->getLocStart(), BaseExpr,
S.PDiag(diag::note_array_index_out_of_bounds)
<< ND->getDeclName());
}
void Sema::CheckArrayAccess(const Expr *expr) {
while (true)
switch (expr->getStmtClass()) {
case Stmt::ParenExprClass:
expr = cast<ParenExpr>(expr)->getSubExpr();
continue;
case Stmt::ArraySubscriptExprClass:
CheckArrayAccess_Check(*this, cast<ArraySubscriptExpr>(expr));
return;
case Stmt::ConditionalOperatorClass: {
const ConditionalOperator *cond = cast<ConditionalOperator>(expr);
if (const Expr *lhs = cond->getLHS())
CheckArrayAccess(lhs);
if (const Expr *rhs = cond->getRHS())
CheckArrayAccess(rhs);
return;
}
default:
return;
}
}