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gerrit-public.fairphone.software / fp2-dev / platform / external / clang / 4c45aa1b00b91847acfb082acfaced3ffa294d1d / . / 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 "Sema.h"
#include "clang/Analysis/CFG.h"
#include "clang/Analysis/PathSensitive/AnalysisContext.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/CharUnits.h"
#include "clang/AST/DeclObjC.h"
#include "clang/AST/ExprCXX.h"
#include "clang/AST/ExprObjC.h"
#include "clang/AST/DeclObjC.h"
#include "clang/AST/StmtCXX.h"
#include "clang/AST/StmtObjC.h"
#include "clang/Lex/LiteralSupport.h"
#include "clang/Lex/Preprocessor.h"
#include "llvm/ADT/BitVector.h"
#include "llvm/ADT/STLExtras.h"
#include <limits>
#include <queue>
using namespace clang;
/// getLocationOfStringLiteralByte - Return a source location that points to the
/// specified byte of the specified string literal.
///
/// Strings are amazingly complex. They can be formed from multiple tokens and
/// can have escape sequences in them in addition to the usual trigraph and
/// escaped newline business. This routine handles this complexity.
///
SourceLocation Sema::getLocationOfStringLiteralByte(const StringLiteral *SL,
unsigned ByteNo) const {
assert(!SL->isWide() && "This doesn't work for wide strings yet");
// Loop over all of the tokens in this string until we find the one that
// contains the byte we're looking for.
unsigned TokNo = 0;
while (1) {
assert(TokNo < SL->getNumConcatenated() && "Invalid byte number!");
SourceLocation StrTokLoc = SL->getStrTokenLoc(TokNo);
// Get the spelling of the string so that we can get the data that makes up
// the string literal, not the identifier for the macro it is potentially
// expanded through.
SourceLocation StrTokSpellingLoc = SourceMgr.getSpellingLoc(StrTokLoc);
// Re-lex the token to get its length and original spelling.
std::pair<FileID, unsigned> LocInfo =
SourceMgr.getDecomposedLoc(StrTokSpellingLoc);
std::pair<const char *,const char *> Buffer =
SourceMgr.getBufferData(LocInfo.first);
const char *StrData = Buffer.first+LocInfo.second;
// Create a langops struct and enable trigraphs. This is sufficient for
// relexing tokens.
LangOptions LangOpts;
LangOpts.Trigraphs = true;
// Create a lexer starting at the beginning of this token.
Lexer TheLexer(StrTokSpellingLoc, LangOpts, Buffer.first, StrData,
Buffer.second);
Token TheTok;
TheLexer.LexFromRawLexer(TheTok);
// Use the StringLiteralParser to compute the length of the string in bytes.
StringLiteralParser SLP(&TheTok, 1, PP);
unsigned TokNumBytes = SLP.GetStringLength();
// If the byte is in this token, return the location of the byte.
if (ByteNo < TokNumBytes ||
(ByteNo == TokNumBytes && TokNo == SL->getNumConcatenated())) {
unsigned Offset =
StringLiteralParser::getOffsetOfStringByte(TheTok, ByteNo, PP);
// Now that we know the offset of the token in the spelling, use the
// preprocessor to get the offset in the original source.
return PP.AdvanceToTokenCharacter(StrTokLoc, Offset);
}
// Move to the next string token.
++TokNo;
ByteNo -= TokNumBytes;
}
}
/// CheckablePrintfAttr - does a function call have a "printf" attribute
/// and arguments that merit checking?
bool Sema::CheckablePrintfAttr(const FormatAttr *Format, CallExpr *TheCall) {
if (Format->getType() == "printf") return true;
if (Format->getType() == "printf0") {
// printf0 allows null "format" string; if so don't check format/args
unsigned format_idx = Format->getFormatIdx() - 1;
// Does the index refer to the implicit object argument?
if (isa<CXXMemberCallExpr>(TheCall)) {
if (format_idx == 0)
return false;
--format_idx;
}
if (format_idx < TheCall->getNumArgs()) {
Expr *Format = TheCall->getArg(format_idx)->IgnoreParenCasts();
if (!Format->isNullPointerConstant(Context, Expr::NPC_ValueDependentIsNull))
return true;
}
}
return false;
}
Action::OwningExprResult
Sema::CheckBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
OwningExprResult TheCallResult(Owned(TheCall));
switch (BuiltinID) {
case Builtin::BI__builtin___CFStringMakeConstantString:
assert(TheCall->getNumArgs() == 1 &&
"Wrong # arguments to builtin CFStringMakeConstantString");
if (CheckObjCString(TheCall->getArg(0)))
return ExprError();
break;
case Builtin::BI__builtin_stdarg_start:
case Builtin::BI__builtin_va_start:
if (SemaBuiltinVAStart(TheCall))
return ExprError();
break;
case Builtin::BI__builtin_isgreater:
case Builtin::BI__builtin_isgreaterequal:
case Builtin::BI__builtin_isless:
case Builtin::BI__builtin_islessequal:
case Builtin::BI__builtin_islessgreater:
case Builtin::BI__builtin_isunordered:
if (SemaBuiltinUnorderedCompare(TheCall))
return ExprError();
break;
case Builtin::BI__builtin_isfinite:
case Builtin::BI__builtin_isinf:
case Builtin::BI__builtin_isinf_sign:
case Builtin::BI__builtin_isnan:
case Builtin::BI__builtin_isnormal:
if (SemaBuiltinUnaryFP(TheCall))
return ExprError();
break;
case Builtin::BI__builtin_return_address:
case Builtin::BI__builtin_frame_address:
if (SemaBuiltinStackAddress(TheCall))
return ExprError();
break;
case Builtin::BI__builtin_eh_return_data_regno:
if (SemaBuiltinEHReturnDataRegNo(TheCall))
return ExprError();
break;
case Builtin::BI__builtin_shufflevector:
return SemaBuiltinShuffleVector(TheCall);
// TheCall will be freed by the smart pointer here, but that's fine, since
// SemaBuiltinShuffleVector guts it, but then doesn't release it.
case Builtin::BI__builtin_prefetch:
if (SemaBuiltinPrefetch(TheCall))
return ExprError();
break;
case Builtin::BI__builtin_object_size:
if (SemaBuiltinObjectSize(TheCall))
return ExprError();
break;
case Builtin::BI__builtin_longjmp:
if (SemaBuiltinLongjmp(TheCall))
return ExprError();
break;
case Builtin::BI__sync_fetch_and_add:
case Builtin::BI__sync_fetch_and_sub:
case Builtin::BI__sync_fetch_and_or:
case Builtin::BI__sync_fetch_and_and:
case Builtin::BI__sync_fetch_and_xor:
case Builtin::BI__sync_fetch_and_nand:
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_nand_and_fetch:
case Builtin::BI__sync_val_compare_and_swap:
case Builtin::BI__sync_bool_compare_and_swap:
case Builtin::BI__sync_lock_test_and_set:
case Builtin::BI__sync_lock_release:
if (SemaBuiltinAtomicOverloaded(TheCall))
return ExprError();
break;
}
return move(TheCallResult);
}
/// CheckFunctionCall - Check a direct function call for various correctness
/// and safety properties not strictly enforced by the C type system.
bool Sema::CheckFunctionCall(FunctionDecl *FDecl, CallExpr *TheCall) {
// Get the IdentifierInfo* for the called function.
IdentifierInfo *FnInfo = FDecl->getIdentifier();
// None of the checks below are needed for functions that don't have
// simple names (e.g., C++ conversion functions).
if (!FnInfo)
return false;
// FIXME: This mechanism should be abstracted to be less fragile and
// more efficient. For example, just map function ids to custom
// handlers.
// Printf checking.
if (const FormatAttr *Format = FDecl->getAttr<FormatAttr>()) {
if (CheckablePrintfAttr(Format, TheCall)) {
bool HasVAListArg = Format->getFirstArg() == 0;
if (!HasVAListArg) {
if (const FunctionProtoType *Proto
= FDecl->getType()->getAs<FunctionProtoType>())
HasVAListArg = !Proto->isVariadic();
}
CheckPrintfArguments(TheCall, HasVAListArg, Format->getFormatIdx() - 1,
HasVAListArg ? 0 : Format->getFirstArg() - 1);
}
}
for (const NonNullAttr *NonNull = FDecl->getAttr<NonNullAttr>(); NonNull;
NonNull = NonNull->getNext<NonNullAttr>())
CheckNonNullArguments(NonNull, TheCall);
return false;
}
bool Sema::CheckBlockCall(NamedDecl *NDecl, CallExpr *TheCall) {
// Printf checking.
const FormatAttr *Format = NDecl->getAttr<FormatAttr>();
if (!Format)
return false;
const VarDecl *V = dyn_cast<VarDecl>(NDecl);
if (!V)
return false;
QualType Ty = V->getType();
if (!Ty->isBlockPointerType())
return false;
if (!CheckablePrintfAttr(Format, TheCall))
return false;
bool HasVAListArg = Format->getFirstArg() == 0;
if (!HasVAListArg) {
const FunctionType *FT =
Ty->getAs<BlockPointerType>()->getPointeeType()->getAs<FunctionType>();
if (const FunctionProtoType *Proto = dyn_cast<FunctionProtoType>(FT))
HasVAListArg = !Proto->isVariadic();
}
CheckPrintfArguments(TheCall, HasVAListArg, Format->getFormatIdx() - 1,
HasVAListArg ? 0 : Format->getFirstArg() - 1);
return false;
}
/// SemaBuiltinAtomicOverloaded - We have a call to a function like
/// __sync_fetch_and_add, which is an overloaded function based on the pointer
/// type of its first argument. The main ActOnCallExpr routines have already
/// promoted the types of arguments because all of these calls are prototyped as
/// void(...).
///
/// This function goes through and does final semantic checking for these
/// builtins,
bool Sema::SemaBuiltinAtomicOverloaded(CallExpr *TheCall) {
DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts());
FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl());
// Ensure that we have at least one argument to do type inference from.
if (TheCall->getNumArgs() < 1)
return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args)
<< 0 << TheCall->getCallee()->getSourceRange();
// Inspect the first argument of the atomic builtin. This should always be
// a pointer type, whose element is an integral scalar or pointer type.
// Because it is a pointer type, we don't have to worry about any implicit
// casts here.
Expr *FirstArg = TheCall->getArg(0);
if (!FirstArg->getType()->isPointerType())
return Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer)
<< FirstArg->getType() << FirstArg->getSourceRange();
QualType ValType = FirstArg->getType()->getAs<PointerType>()->getPointeeType();
if (!ValType->isIntegerType() && !ValType->isPointerType() &&
!ValType->isBlockPointerType())
return Diag(DRE->getLocStart(),
diag::err_atomic_builtin_must_be_pointer_intptr)
<< FirstArg->getType() << FirstArg->getSourceRange();
// We need to figure out which concrete builtin this maps onto. For example,
// __sync_fetch_and_add with a 2 byte object turns into
// __sync_fetch_and_add_2.
#define BUILTIN_ROW(x) \
{ Builtin::BI##x##_1, Builtin::BI##x##_2, Builtin::BI##x##_4, \
Builtin::BI##x##_8, Builtin::BI##x##_16 }
static const unsigned BuiltinIndices[][5] = {
BUILTIN_ROW(__sync_fetch_and_add),
BUILTIN_ROW(__sync_fetch_and_sub),
BUILTIN_ROW(__sync_fetch_and_or),
BUILTIN_ROW(__sync_fetch_and_and),
BUILTIN_ROW(__sync_fetch_and_xor),
BUILTIN_ROW(__sync_fetch_and_nand),
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_nand_and_fetch),
BUILTIN_ROW(__sync_val_compare_and_swap),
BUILTIN_ROW(__sync_bool_compare_and_swap),
BUILTIN_ROW(__sync_lock_test_and_set),
BUILTIN_ROW(__sync_lock_release)
};
#undef BUILTIN_ROW
// Determine the index of the size.
unsigned SizeIndex;
switch (Context.getTypeSizeInChars(ValType).getQuantity()) {
case 1: SizeIndex = 0; break;
case 2: SizeIndex = 1; break;
case 4: SizeIndex = 2; break;
case 8: SizeIndex = 3; break;
case 16: SizeIndex = 4; break;
default:
return Diag(DRE->getLocStart(), diag::err_atomic_builtin_pointer_size)
<< FirstArg->getType() << FirstArg->getSourceRange();
}
// Each of these builtins has one pointer argument, followed by some number of
// values (0, 1 or 2) followed by a potentially empty varags list of stuff
// that we ignore. Find out which row of BuiltinIndices to read from as well
// as the number of fixed args.
unsigned BuiltinID = FDecl->getBuiltinID();
unsigned BuiltinIndex, NumFixed = 1;
switch (BuiltinID) {
default: assert(0 && "Unknown overloaded atomic builtin!");
case Builtin::BI__sync_fetch_and_add: BuiltinIndex = 0; break;
case Builtin::BI__sync_fetch_and_sub: BuiltinIndex = 1; break;
case Builtin::BI__sync_fetch_and_or: BuiltinIndex = 2; break;
case Builtin::BI__sync_fetch_and_and: BuiltinIndex = 3; break;
case Builtin::BI__sync_fetch_and_xor: BuiltinIndex = 4; break;
case Builtin::BI__sync_fetch_and_nand:BuiltinIndex = 5; break;
case Builtin::BI__sync_add_and_fetch: BuiltinIndex = 6; break;
case Builtin::BI__sync_sub_and_fetch: BuiltinIndex = 7; break;
case Builtin::BI__sync_and_and_fetch: BuiltinIndex = 8; break;
case Builtin::BI__sync_or_and_fetch: BuiltinIndex = 9; break;
case Builtin::BI__sync_xor_and_fetch: BuiltinIndex =10; break;
case Builtin::BI__sync_nand_and_fetch:BuiltinIndex =11; break;
case Builtin::BI__sync_val_compare_and_swap:
BuiltinIndex = 12;
NumFixed = 2;
break;
case Builtin::BI__sync_bool_compare_and_swap:
BuiltinIndex = 13;
NumFixed = 2;
break;
case Builtin::BI__sync_lock_test_and_set: BuiltinIndex = 14; break;
case Builtin::BI__sync_lock_release:
BuiltinIndex = 15;
NumFixed = 0;
break;
}
// Now that we know how many fixed arguments we expect, first check that we
// have at least that many.
if (TheCall->getNumArgs() < 1+NumFixed)
return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args)
<< 0 << TheCall->getCallee()->getSourceRange();
// Get the decl for the concrete builtin from this, we can tell what the
// concrete integer type we should convert to is.
unsigned NewBuiltinID = BuiltinIndices[BuiltinIndex][SizeIndex];
const char *NewBuiltinName = Context.BuiltinInfo.GetName(NewBuiltinID);
IdentifierInfo *NewBuiltinII = PP.getIdentifierInfo(NewBuiltinName);
FunctionDecl *NewBuiltinDecl =
cast<FunctionDecl>(LazilyCreateBuiltin(NewBuiltinII, NewBuiltinID,
TUScope, false, DRE->getLocStart()));
const FunctionProtoType *BuiltinFT =
NewBuiltinDecl->getType()->getAs<FunctionProtoType>();
ValType = BuiltinFT->getArgType(0)->getAs<PointerType>()->getPointeeType();
// If the first type needs to be converted (e.g. void** -> int*), do it now.
if (BuiltinFT->getArgType(0) != FirstArg->getType()) {
ImpCastExprToType(FirstArg, BuiltinFT->getArgType(0), CastExpr::CK_BitCast);
TheCall->setArg(0, FirstArg);
}
// Next, walk the valid ones promoting to the right type.
for (unsigned i = 0; i != NumFixed; ++i) {
Expr *Arg = TheCall->getArg(i+1);
// If the argument is an implicit cast, then there was a promotion due to
// "...", just remove it now.
if (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Arg)) {
Arg = ICE->getSubExpr();
ICE->setSubExpr(0);
ICE->Destroy(Context);
TheCall->setArg(i+1, Arg);
}
// GCC does an implicit conversion to the pointer or integer ValType. This
// can fail in some cases (1i -> int**), check for this error case now.
CastExpr::CastKind Kind = CastExpr::CK_Unknown;
CXXMethodDecl *ConversionDecl = 0;
if (CheckCastTypes(Arg->getSourceRange(), ValType, Arg, Kind,
ConversionDecl))
return true;
// Okay, we have something that *can* be converted to the right type. Check
// to see if there is a potentially weird extension going on here. This can
// happen when you do an atomic operation on something like an char* and
// pass in 42. The 42 gets converted to char. This is even more strange
// for things like 45.123 -> char, etc.
// FIXME: Do this check.
ImpCastExprToType(Arg, ValType, Kind, /*isLvalue=*/false);
TheCall->setArg(i+1, Arg);
}
// Switch the DeclRefExpr to refer to the new decl.
DRE->setDecl(NewBuiltinDecl);
DRE->setType(NewBuiltinDecl->getType());
// Set the callee in the CallExpr.
// FIXME: This leaks the original parens and implicit casts.
Expr *PromotedCall = DRE;
UsualUnaryConversions(PromotedCall);
TheCall->setCallee(PromotedCall);
// Change the result type of the call to match the result type of the decl.
TheCall->setType(NewBuiltinDecl->getResultType());
return false;
}
/// CheckObjCString - Checks that the argument to the builtin
/// CFString constructor is correct
/// FIXME: GCC currently emits the following warning:
/// "warning: input conversion stopped due to an input byte that does not
/// belong to the input codeset UTF-8"
/// Note: It might also make sense to do the UTF-16 conversion here (would
/// simplify the backend).
bool Sema::CheckObjCString(Expr *Arg) {
Arg = Arg->IgnoreParenCasts();
StringLiteral *Literal = dyn_cast<StringLiteral>(Arg);
if (!Literal || Literal->isWide()) {
Diag(Arg->getLocStart(), diag::err_cfstring_literal_not_string_constant)
<< Arg->getSourceRange();
return true;
}
const char *Data = Literal->getStrData();
unsigned Length = Literal->getByteLength();
for (unsigned i = 0; i < Length; ++i) {
if (!Data[i]) {
Diag(getLocationOfStringLiteralByte(Literal, i),
diag::warn_cfstring_literal_contains_nul_character)
<< Arg->getSourceRange();
break;
}
}
return false;
}
/// SemaBuiltinVAStart - Check the arguments to __builtin_va_start for validity.
/// Emit an error and return true on failure, return false on success.
bool Sema::SemaBuiltinVAStart(CallExpr *TheCall) {
Expr *Fn = TheCall->getCallee();
if (TheCall->getNumArgs() > 2) {
Diag(TheCall->getArg(2)->getLocStart(),
diag::err_typecheck_call_too_many_args)
<< 0 /*function call*/ << 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)
<< 0 /*function call*/;
}
// Determine whether the current function is variadic or not.
bool isVariadic;
if (CurBlock)
isVariadic = CurBlock->isVariadic;
else if (getCurFunctionDecl()) {
if (FunctionProtoType* FTP =
dyn_cast<FunctionProtoType>(getCurFunctionDecl()->getType()))
isVariadic = FTP->isVariadic();
else
isVariadic = false;
} 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 /*function call*/;
if (TheCall->getNumArgs() > 2)
return Diag(TheCall->getArg(2)->getLocStart(),
diag::err_typecheck_call_too_many_args)
<< 0 /*function call*/
<< 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;
}
/// SemaBuiltinUnorderedCompare - Handle functions like __builtin_isnan and
/// friends. This is declared to take (...), so we have to check everything.
bool Sema::SemaBuiltinUnaryFP(CallExpr *TheCall) {
if (TheCall->getNumArgs() < 1)
return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args)
<< 0 /*function call*/;
if (TheCall->getNumArgs() > 1)
return Diag(TheCall->getArg(1)->getLocStart(),
diag::err_typecheck_call_too_many_args)
<< 0 /*function call*/
<< SourceRange(TheCall->getArg(1)->getLocStart(),
(*(TheCall->arg_end()-1))->getLocEnd());
Expr *OrigArg = TheCall->getArg(0);
if (OrigArg->isTypeDependent())
return false;
// This operation requires a floating-point number
if (!OrigArg->getType()->isRealFloatingType())
return Diag(OrigArg->getLocStart(),
diag::err_typecheck_call_invalid_unary_fp)
<< OrigArg->getType() << OrigArg->getSourceRange();
return false;
}
bool Sema::SemaBuiltinStackAddress(CallExpr *TheCall) {
// The signature for these builtins is exact; the only thing we need
// to check is that the argument is a constant.
SourceLocation Loc;
if (!TheCall->getArg(0)->isTypeDependent() &&
!TheCall->getArg(0)->isValueDependent() &&
!TheCall->getArg(0)->isIntegerConstantExpr(Context, &Loc))
return Diag(Loc, diag::err_stack_const_level) << TheCall->getSourceRange();
return false;
}
/// SemaBuiltinShuffleVector - Handle __builtin_shufflevector.
// This is declared to take (...), so we have to check everything.
Action::OwningExprResult Sema::SemaBuiltinShuffleVector(CallExpr *TheCall) {
if (TheCall->getNumArgs() < 3)
return ExprError(Diag(TheCall->getLocEnd(),
diag::err_typecheck_call_too_few_args)
<< 0 /*function call*/ << TheCall->getSourceRange());
unsigned numElements = std::numeric_limits<unsigned>::max();
if (!TheCall->getArg(0)->isTypeDependent() &&
!TheCall->getArg(1)->isTypeDependent()) {
QualType FAType = TheCall->getArg(0)->getType();
QualType SAType = TheCall->getArg(1)->getType();
if (!FAType->isVectorType() || !SAType->isVectorType()) {
Diag(TheCall->getLocStart(), diag::err_shufflevector_non_vector)
<< SourceRange(TheCall->getArg(0)->getLocStart(),
TheCall->getArg(1)->getLocEnd());
return ExprError();
}
if (!Context.hasSameUnqualifiedType(FAType, SAType)) {
Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector)
<< SourceRange(TheCall->getArg(0)->getLocStart(),
TheCall->getArg(1)->getLocEnd());
return ExprError();
}
numElements = FAType->getAs<VectorType>()->getNumElements();
if (TheCall->getNumArgs() != numElements+2) {
if (TheCall->getNumArgs() < numElements+2)
return ExprError(Diag(TheCall->getLocEnd(),
diag::err_typecheck_call_too_few_args)
<< 0 /*function call*/ << TheCall->getSourceRange());
return ExprError(Diag(TheCall->getLocEnd(),
diag::err_typecheck_call_too_many_args)
<< 0 /*function call*/ << TheCall->getSourceRange());
}
}
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(), exprs[0]->getType(),
TheCall->getCallee()->getLocStart(),
TheCall->getRParenLoc()));
}
/// SemaBuiltinPrefetch - Handle __builtin_prefetch.
// This is declared to take (const void*, ...) and can take two
// optional constant int args.
bool Sema::SemaBuiltinPrefetch(CallExpr *TheCall) {
unsigned NumArgs = TheCall->getNumArgs();
if (NumArgs > 3)
return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_many_args)
<< 0 /*function call*/ << 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);
if (Arg->isTypeDependent())
continue;
if (!Arg->getType()->isIntegralType())
return Diag(TheCall->getLocStart(), diag::err_prefetch_invalid_arg_type)
<< Arg->getSourceRange();
ImpCastExprToType(Arg, Context.IntTy, CastExpr::CK_IntegralCast);
TheCall->setArg(i, Arg);
if (Arg->isValueDependent())
continue;
llvm::APSInt Result;
if (!Arg->isIntegerConstantExpr(Result, Context))
return Diag(TheCall->getLocStart(), diag::err_prefetch_invalid_arg_ice)
<< SourceRange(Arg->getLocStart(), Arg->getLocEnd());
// 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;
}
/// SemaBuiltinEHReturnDataRegNo - Handle __builtin_eh_return_data_regno, the
/// operand must be an integer constant.
bool Sema::SemaBuiltinEHReturnDataRegNo(CallExpr *TheCall) {
llvm::APSInt Result;
if (!TheCall->getArg(0)->isIntegerConstantExpr(Result, Context))
return Diag(TheCall->getLocStart(), diag::err_expr_not_ice)
<< TheCall->getArg(0)->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) {
Expr *Arg = TheCall->getArg(1);
if (Arg->isTypeDependent())
return false;
QualType ArgType = Arg->getType();
const BuiltinType *BT = ArgType->getAs<BuiltinType>();
llvm::APSInt Result(32);
if (!BT || BT->getKind() != BuiltinType::Int)
return Diag(TheCall->getLocStart(), diag::err_object_size_invalid_argument)
<< SourceRange(Arg->getLocStart(), Arg->getLocEnd());
if (Arg->isValueDependent())
return false;
if (!Arg->isIntegerConstantExpr(Result, Context)) {
return Diag(TheCall->getLocStart(), diag::err_object_size_invalid_argument)
<< SourceRange(Arg->getLocStart(), Arg->getLocEnd());
}
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);
if (Arg->isTypeDependent() || Arg->isValueDependent())
return false;
llvm::APSInt Result(32);
if (!Arg->isIntegerConstantExpr(Result, Context) || Result != 1)
return Diag(TheCall->getLocStart(), diag::err_builtin_longjmp_invalid_val)
<< SourceRange(Arg->getLocStart(), Arg->getLocEnd());
return false;
}
// Handle i > 1 ? "x" : "y", recursivelly
bool Sema::SemaCheckStringLiteral(const Expr *E, const CallExpr *TheCall,
bool HasVAListArg,
unsigned format_idx, unsigned firstDataArg) {
if (E->isTypeDependent() || E->isValueDependent())
return false;
switch (E->getStmtClass()) {
case Stmt::ConditionalOperatorClass: {
const ConditionalOperator *C = cast<ConditionalOperator>(E);
return SemaCheckStringLiteral(C->getTrueExpr(), TheCall,
HasVAListArg, format_idx, firstDataArg)
&& SemaCheckStringLiteral(C->getRHS(), TheCall,
HasVAListArg, format_idx, firstDataArg);
}
case Stmt::ImplicitCastExprClass: {
const ImplicitCastExpr *Expr = cast<ImplicitCastExpr>(E);
return SemaCheckStringLiteral(Expr->getSubExpr(), TheCall, HasVAListArg,
format_idx, firstDataArg);
}
case Stmt::ParenExprClass: {
const ParenExpr *Expr = cast<ParenExpr>(E);
return SemaCheckStringLiteral(Expr->getSubExpr(), TheCall, HasVAListArg,
format_idx, firstDataArg);
}
case Stmt::DeclRefExprClass: {
const DeclRefExpr *DR = cast<DeclRefExpr>(E);
// As an exception, do not flag errors for variables binding to
// const string literals.
if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) {
bool isConstant = false;
QualType T = DR->getType();
if (const ArrayType *AT = Context.getAsArrayType(T)) {
isConstant = AT->getElementType().isConstant(Context);
} else if (const PointerType *PT = T->getAs<PointerType>()) {
isConstant = T.isConstant(Context) &&
PT->getPointeeType().isConstant(Context);
}
if (isConstant) {
const VarDecl *Def = 0;
if (const Expr *Init = VD->getDefinition(Def))
return SemaCheckStringLiteral(Init, TheCall,
HasVAListArg, format_idx, firstDataArg);
}
// For vprintf* functions (i.e., HasVAListArg==true), we add a
// special check to see if the format string is a function parameter
// of the function calling the printf function. If the function
// has an attribute indicating it is a printf-like function, then we
// should suppress warnings concerning non-literals being used in a call
// to a vprintf function. For example:
//
// void
// logmessage(char const *fmt __attribute__ (format (printf, 1, 2)), ...){
// va_list ap;
// va_start(ap, fmt);
// vprintf(fmt, ap); // Do NOT emit a warning about "fmt".
// ...
//
//
// FIXME: We don't have full attribute support yet, so just check to see
// if the argument is a DeclRefExpr that references a parameter. We'll
// add proper support for checking the attribute later.
if (HasVAListArg)
if (isa<ParmVarDecl>(VD))
return true;
}
return false;
}
case Stmt::CallExprClass: {
const CallExpr *CE = cast<CallExpr>(E);
if (const ImplicitCastExpr *ICE
= dyn_cast<ImplicitCastExpr>(CE->getCallee())) {
if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(ICE->getSubExpr())) {
if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(DRE->getDecl())) {
if (const FormatArgAttr *FA = FD->getAttr<FormatArgAttr>()) {
unsigned ArgIndex = FA->getFormatIdx();
const Expr *Arg = CE->getArg(ArgIndex - 1);
return SemaCheckStringLiteral(Arg, TheCall, HasVAListArg,
format_idx, firstDataArg);
}
}
}
}
return false;
}
case Stmt::ObjCStringLiteralClass:
case Stmt::StringLiteralClass: {
const StringLiteral *StrE = NULL;
if (const ObjCStringLiteral *ObjCFExpr = dyn_cast<ObjCStringLiteral>(E))
StrE = ObjCFExpr->getString();
else
StrE = cast<StringLiteral>(E);
if (StrE) {
CheckPrintfString(StrE, E, TheCall, HasVAListArg, format_idx,
firstDataArg);
return true;
}
return false;
}
default:
return false;
}
}
void
Sema::CheckNonNullArguments(const NonNullAttr *NonNull,
const CallExpr *TheCall) {
for (NonNullAttr::iterator i = NonNull->begin(), e = NonNull->end();
i != e; ++i) {
const Expr *ArgExpr = TheCall->getArg(*i);
if (ArgExpr->isNullPointerConstant(Context,
Expr::NPC_ValueDependentIsNotNull))
Diag(TheCall->getCallee()->getLocStart(), diag::warn_null_arg)
<< ArgExpr->getSourceRange();
}
}
/// CheckPrintfArguments - Check calls to printf (and similar functions) for
/// correct use of format strings.
///
/// HasVAListArg - A predicate indicating whether the printf-like
/// function is passed an explicit va_arg argument (e.g., vprintf)
///
/// format_idx - The index into Args for the format string.
///
/// Improper format strings to functions in the printf family can be
/// the source of bizarre bugs and very serious security holes. A
/// good source of information is available in the following paper
/// (which includes additional references):
///
/// FormatGuard: Automatic Protection From printf Format String
/// Vulnerabilities, Proceedings of the 10th USENIX Security Symposium, 2001.
///
/// Functionality implemented:
///
/// We can statically check the following properties for string
/// literal format strings for non v.*printf functions (where the
/// arguments are passed directly):
//
/// (1) Are the number of format conversions equal to the number of
/// data arguments?
///
/// (2) Does each format conversion correctly match the type of the
/// corresponding data argument? (TODO)
///
/// Moreover, for all printf functions we can:
///
/// (3) Check for a missing format string (when not caught by type checking).
///
/// (4) Check for no-operation flags; e.g. using "#" with format
/// conversion 'c' (TODO)
///
/// (5) Check the use of '%n', a major source of security holes.
///
/// (6) Check for malformed format conversions that don't specify anything.
///
/// (7) Check for empty format strings. e.g: printf("");
///
/// (8) Check that the format string is a wide literal.
///
/// All of these checks can be done by parsing the format string.
///
/// For now, we ONLY do (1), (3), (5), (6), (7), and (8).
void
Sema::CheckPrintfArguments(const CallExpr *TheCall, bool HasVAListArg,
unsigned format_idx, unsigned firstDataArg) {
const Expr *Fn = TheCall->getCallee();
// The way the format attribute works in GCC, the implicit this argument
// of member functions is counted. However, it doesn't appear in our own
// lists, so decrement format_idx in that case.
if (isa<CXXMemberCallExpr>(TheCall)) {
// Catch a format attribute mistakenly referring to the object argument.
if (format_idx == 0)
return;
--format_idx;
if(firstDataArg != 0)
--firstDataArg;
}
// CHECK: printf-like function is called with no format string.
if (format_idx >= TheCall->getNumArgs()) {
Diag(TheCall->getRParenLoc(), diag::warn_printf_missing_format_string)
<< Fn->getSourceRange();
return;
}
const Expr *OrigFormatExpr = TheCall->getArg(format_idx)->IgnoreParenCasts();
// CHECK: format string is not a string literal.
//
// Dynamically generated format strings are difficult to
// automatically vet at compile time. Requiring that format strings
// are string literals: (1) permits the checking of format strings by
// the compiler and thereby (2) can practically remove the source of
// many format string exploits.
// Format string can be either ObjC string (e.g. @"%d") or
// C string (e.g. "%d")
// ObjC string uses the same format specifiers as C string, so we can use
// the same format string checking logic for both ObjC and C strings.
if (SemaCheckStringLiteral(OrigFormatExpr, TheCall, HasVAListArg, format_idx,
firstDataArg))
return; // Literal format string found, check done!
// If there are no arguments specified, warn with -Wformat-security, otherwise
// warn only with -Wformat-nonliteral.
if (TheCall->getNumArgs() == format_idx+1)
Diag(TheCall->getArg(format_idx)->getLocStart(),
diag::warn_printf_nonliteral_noargs)
<< OrigFormatExpr->getSourceRange();
else
Diag(TheCall->getArg(format_idx)->getLocStart(),
diag::warn_printf_nonliteral)
<< OrigFormatExpr->getSourceRange();
}
void Sema::CheckPrintfString(const StringLiteral *FExpr,
const Expr *OrigFormatExpr,
const CallExpr *TheCall, bool HasVAListArg,
unsigned format_idx, unsigned firstDataArg) {
const ObjCStringLiteral *ObjCFExpr =
dyn_cast<ObjCStringLiteral>(OrigFormatExpr);
// CHECK: is the format string a wide literal?
if (FExpr->isWide()) {
Diag(FExpr->getLocStart(),
diag::warn_printf_format_string_is_wide_literal)
<< OrigFormatExpr->getSourceRange();
return;
}
// Str - The format string. NOTE: this is NOT null-terminated!
const char *Str = FExpr->getStrData();
// CHECK: empty format string?
unsigned StrLen = FExpr->getByteLength();
if (StrLen == 0) {
Diag(FExpr->getLocStart(), diag::warn_printf_empty_format_string)
<< OrigFormatExpr->getSourceRange();
return;
}
// We process the format string using a binary state machine. The
// current state is stored in CurrentState.
enum {
state_OrdChr,
state_Conversion
} CurrentState = state_OrdChr;
// numConversions - The number of conversions seen so far. This is
// incremented as we traverse the format string.
unsigned numConversions = 0;
// numDataArgs - The number of data arguments after the format
// string. This can only be determined for non vprintf-like
// functions. For those functions, this value is 1 (the sole
// va_arg argument).
unsigned numDataArgs = TheCall->getNumArgs()-firstDataArg;
// Inspect the format string.
unsigned StrIdx = 0;
// LastConversionIdx - Index within the format string where we last saw
// a '%' character that starts a new format conversion.
unsigned LastConversionIdx = 0;
for (; StrIdx < StrLen; ++StrIdx) {
// Is the number of detected conversion conversions greater than
// the number of matching data arguments? If so, stop.
if (!HasVAListArg && numConversions > numDataArgs) break;
// Handle "\0"
if (Str[StrIdx] == '\0') {
// The string returned by getStrData() is not null-terminated,
// so the presence of a null character is likely an error.
Diag(getLocationOfStringLiteralByte(FExpr, StrIdx),
diag::warn_printf_format_string_contains_null_char)
<< OrigFormatExpr->getSourceRange();
return;
}
// Ordinary characters (not processing a format conversion).
if (CurrentState == state_OrdChr) {
if (Str[StrIdx] == '%') {
CurrentState = state_Conversion;
LastConversionIdx = StrIdx;
}
continue;
}
// Seen '%'. Now processing a format conversion.
switch (Str[StrIdx]) {
// Handle dynamic precision or width specifier.
case '*': {
++numConversions;
if (!HasVAListArg) {
if (numConversions > numDataArgs) {
SourceLocation Loc = getLocationOfStringLiteralByte(FExpr, StrIdx);
if (Str[StrIdx-1] == '.')
Diag(Loc, diag::warn_printf_asterisk_precision_missing_arg)
<< OrigFormatExpr->getSourceRange();
else
Diag(Loc, diag::warn_printf_asterisk_width_missing_arg)
<< OrigFormatExpr->getSourceRange();
// Don't do any more checking. We'll just emit spurious errors.
return;
}
// Perform type checking on width/precision specifier.
const Expr *E = TheCall->getArg(format_idx+numConversions);
if (const BuiltinType *BT = E->getType()->getAs<BuiltinType>())
if (BT->getKind() == BuiltinType::Int)
break;
SourceLocation Loc = getLocationOfStringLiteralByte(FExpr, StrIdx);
if (Str[StrIdx-1] == '.')
Diag(Loc, diag::warn_printf_asterisk_precision_wrong_type)
<< E->getType() << E->getSourceRange();
else
Diag(Loc, diag::warn_printf_asterisk_width_wrong_type)
<< E->getType() << E->getSourceRange();
break;
}
}
// Characters which can terminate a format conversion
// (e.g. "%d"). Characters that specify length modifiers or
// other flags are handled by the default case below.
//
// FIXME: additional checks will go into the following cases.
case 'i':
case 'd':
case 'o':
case 'u':
case 'x':
case 'X':
case 'D':
case 'O':
case 'U':
case 'e':
case 'E':
case 'f':
case 'F':
case 'g':
case 'G':
case 'a':
case 'A':
case 'c':
case 'C':
case 'S':
case 's':
case 'p':
++numConversions;
CurrentState = state_OrdChr;
break;
case 'm':
// FIXME: Warn in situations where this isn't supported!
CurrentState = state_OrdChr;
break;
// CHECK: Are we using "%n"? Issue a warning.
case 'n': {
++numConversions;
CurrentState = state_OrdChr;
SourceLocation Loc = getLocationOfStringLiteralByte(FExpr,
LastConversionIdx);
Diag(Loc, diag::warn_printf_write_back)<<OrigFormatExpr->getSourceRange();
break;
}
// Handle "%@"
case '@':
// %@ is allowed in ObjC format strings only.
if (ObjCFExpr != NULL)
CurrentState = state_OrdChr;
else {
// Issue a warning: invalid format conversion.
SourceLocation Loc =
getLocationOfStringLiteralByte(FExpr, LastConversionIdx);
Diag(Loc, diag::warn_printf_invalid_conversion)
<< std::string(Str+LastConversionIdx,
Str+std::min(LastConversionIdx+2, StrLen))
<< OrigFormatExpr->getSourceRange();
}
++numConversions;
break;
// Handle "%%"
case '%':
// Sanity check: Was the first "%" character the previous one?
// If not, we will assume that we have a malformed format
// conversion, and that the current "%" character is the start
// of a new conversion.
if (StrIdx - LastConversionIdx == 1)
CurrentState = state_OrdChr;
else {
// Issue a warning: invalid format conversion.
SourceLocation Loc =
getLocationOfStringLiteralByte(FExpr, LastConversionIdx);
Diag(Loc, diag::warn_printf_invalid_conversion)
<< std::string(Str+LastConversionIdx, Str+StrIdx)
<< OrigFormatExpr->getSourceRange();
// This conversion is broken. Advance to the next format
// conversion.
LastConversionIdx = StrIdx;
++numConversions;
}
break;
default:
// This case catches all other characters: flags, widths, etc.
// We should eventually process those as well.
break;
}
}
if (CurrentState == state_Conversion) {
// Issue a warning: invalid format conversion.
SourceLocation Loc =
getLocationOfStringLiteralByte(FExpr, LastConversionIdx);
Diag(Loc, diag::warn_printf_invalid_conversion)
<< std::string(Str+LastConversionIdx,
Str+std::min(LastConversionIdx+2, StrLen))
<< OrigFormatExpr->getSourceRange();
return;
}
if (!HasVAListArg) {
// CHECK: Does the number of format conversions exceed the number
// of data arguments?
if (numConversions > numDataArgs) {
SourceLocation Loc =
getLocationOfStringLiteralByte(FExpr, LastConversionIdx);
Diag(Loc, diag::warn_printf_insufficient_data_args)
<< OrigFormatExpr->getSourceRange();
}
// CHECK: Does the number of data arguments exceed the number of
// format conversions in the format string?
else if (numConversions < numDataArgs)
Diag(TheCall->getArg(format_idx+numConversions+1)->getLocStart(),
diag::warn_printf_too_many_data_args)
<< OrigFormatExpr->getSourceRange();
}
}
//===--- CHECK: Return Address of Stack Variable --------------------------===//
static DeclRefExpr* EvalVal(Expr *E);
static DeclRefExpr* EvalAddr(Expr* E);
/// CheckReturnStackAddr - Check if a return statement returns the address
/// of a stack variable.
void
Sema::CheckReturnStackAddr(Expr *RetValExp, QualType lhsType,
SourceLocation ReturnLoc) {
// Perform checking for returned stack addresses.
if (lhsType->isPointerType() || lhsType->isBlockPointerType()) {
if (DeclRefExpr *DR = EvalAddr(RetValExp))
Diag(DR->getLocStart(), diag::warn_ret_stack_addr)
<< DR->getDecl()->getDeclName() << RetValExp->getSourceRange();
// Skip over implicit cast expressions when checking for block expressions.
RetValExp = RetValExp->IgnoreParenCasts();
if (BlockExpr *C = dyn_cast<BlockExpr>(RetValExp))
if (C->hasBlockDeclRefExprs())
Diag(C->getLocStart(), diag::err_ret_local_block)
<< C->getSourceRange();
if (AddrLabelExpr *ALE = dyn_cast<AddrLabelExpr>(RetValExp))
Diag(ALE->getLocStart(), diag::warn_ret_addr_label)
<< ALE->getSourceRange();
} else if (lhsType->isReferenceType()) {
// Perform checking for stack values returned by reference.
// Check for a reference to the stack
if (DeclRefExpr *DR = EvalVal(RetValExp))
Diag(DR->getLocStart(), diag::warn_ret_stack_ref)
<< DR->getDecl()->getDeclName() << RetValExp->getSourceRange();
}
}
/// EvalAddr - EvalAddr and EvalVal are mutually recursive functions that
/// check if the expression in a return statement evaluates to an address
/// to a location on the stack. The recursion is used to traverse the
/// AST of the return expression, with recursion backtracking when we
/// encounter a subexpression that (1) clearly does not lead to the address
/// of a stack variable or (2) is something we cannot determine leads to
/// the address of a stack variable based on such local checking.
///
/// EvalAddr processes expressions that are pointers that are used as
/// references (and not L-values). EvalVal handles all other values.
/// At the base case of the recursion is a check for a DeclRefExpr* in
/// the refers to a stack variable.
///
/// This implementation handles:
///
/// * pointer-to-pointer casts
/// * implicit conversions from array references to pointers
/// * taking the address of fields
/// * arbitrary interplay between "&" and "*" operators
/// * pointer arithmetic from an address of a stack variable
/// * taking the address of an array element where the array is on the stack
static DeclRefExpr* EvalAddr(Expr *E) {
// We should only be called for evaluating pointer expressions.
assert((E->getType()->isAnyPointerType() ||
E->getType()->isBlockPointerType() ||
E->getType()->isObjCQualifiedIdType()) &&
"EvalAddr only works on pointers");
// Our "symbolic interpreter" is just a dispatch off the currently
// viewed AST node. We then recursively traverse the AST by calling
// EvalAddr and EvalVal appropriately.
switch (E->getStmtClass()) {
case Stmt::ParenExprClass:
// Ignore parentheses.
return EvalAddr(cast<ParenExpr>(E)->getSubExpr());
case Stmt::UnaryOperatorClass: {
// The only unary operator that make sense to handle here
// is AddrOf. All others don't make sense as pointers.
UnaryOperator *U = cast<UnaryOperator>(E);
if (U->getOpcode() == UnaryOperator::AddrOf)
return EvalVal(U->getSubExpr());
else
return NULL;
}
case Stmt::BinaryOperatorClass: {
// Handle pointer arithmetic. All other binary operators are not valid
// in this context.
BinaryOperator *B = cast<BinaryOperator>(E);
BinaryOperator::Opcode op = B->getOpcode();
if (op != BinaryOperator::Add && op != BinaryOperator::Sub)
return NULL;
Expr *Base = B->getLHS();
// Determine which argument is the real pointer base. It could be
// the RHS argument instead of the LHS.
if (!Base->getType()->isPointerType()) Base = B->getRHS();
assert (Base->getType()->isPointerType());
return EvalAddr(Base);
}
// For conditional operators we need to see if either the LHS or RHS are
// valid DeclRefExpr*s. If one of them is valid, we return it.
case Stmt::ConditionalOperatorClass: {
ConditionalOperator *C = cast<ConditionalOperator>(E);
// Handle the GNU extension for missing LHS.
if (Expr *lhsExpr = C->getLHS())
if (DeclRefExpr* LHS = EvalAddr(lhsExpr))
return LHS;
return EvalAddr(C->getRHS());
}
// For casts, we need to handle conversions from arrays to
// pointer values, and pointer-to-pointer conversions.
case Stmt::ImplicitCastExprClass:
case Stmt::CStyleCastExprClass:
case Stmt::CXXFunctionalCastExprClass: {
Expr* SubExpr = cast<CastExpr>(E)->getSubExpr();
QualType T = SubExpr->getType();
if (SubExpr->getType()->isPointerType() ||
SubExpr->getType()->isBlockPointerType() ||
SubExpr->getType()->isObjCQualifiedIdType())
return EvalAddr(SubExpr);
else if (T->isArrayType())
return EvalVal(SubExpr);
else
return 0;
}
// C++ casts. For dynamic casts, static casts, and const casts, we
// are always converting from a pointer-to-pointer, so we just blow
// through the cast. In the case the dynamic cast doesn't fail (and
// return NULL), we take the conservative route and report cases
// where we return the address of a stack variable. For Reinterpre
// FIXME: The comment about is wrong; we're not always converting
// from pointer to pointer. I'm guessing that this code should also
// handle references to objects.
case Stmt::CXXStaticCastExprClass:
case Stmt::CXXDynamicCastExprClass:
case Stmt::CXXConstCastExprClass:
case Stmt::CXXReinterpretCastExprClass: {
Expr *S = cast<CXXNamedCastExpr>(E)->getSubExpr();
if (S->getType()->isPointerType() || S->getType()->isBlockPointerType())
return EvalAddr(S);
else
return NULL;
}
// Everything else: we simply don't reason about them.
default:
return NULL;
}
}
/// EvalVal - This function is complements EvalAddr in the mutual recursion.
/// See the comments for EvalAddr for more details.
static DeclRefExpr* EvalVal(Expr *E) {
// We should only be called for evaluating non-pointer expressions, or
// expressions with a pointer type that are not used as references but instead
// are l-values (e.g., DeclRefExpr with a pointer type).
// Our "symbolic interpreter" is just a dispatch off the currently
// viewed AST node. We then recursively traverse the AST by calling
// EvalAddr and EvalVal appropriately.
switch (E->getStmtClass()) {
case Stmt::DeclRefExprClass: {
// DeclRefExpr: the base case. When we hit a DeclRefExpr we are looking
// at code that refers to a variable's name. We check if it has local
// storage within the function, and if so, return the expression.
DeclRefExpr *DR = cast<DeclRefExpr>(E);
if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl()))
if (V->hasLocalStorage() && !V->getType()->isReferenceType()) return DR;
return NULL;
}
case Stmt::ParenExprClass:
// Ignore parentheses.
return EvalVal(cast<ParenExpr>(E)->getSubExpr());
case Stmt::UnaryOperatorClass: {
// The only unary operator that make sense to handle here
// is Deref. All others don't resolve to a "name." This includes
// handling all sorts of rvalues passed to a unary operator.
UnaryOperator *U = cast<UnaryOperator>(E);
if (U->getOpcode() == UnaryOperator::Deref)
return EvalAddr(U->getSubExpr());
return NULL;
}
case Stmt::ArraySubscriptExprClass: {
// Array subscripts are potential references to data on the stack. We
// retrieve the DeclRefExpr* for the array variable if it indeed
// has local storage.
return EvalAddr(cast<ArraySubscriptExpr>(E)->getBase());
}
case Stmt::ConditionalOperatorClass: {
// For conditional operators we need to see if either the LHS or RHS are
// non-NULL DeclRefExpr's. If one is non-NULL, we return it.
ConditionalOperator *C = cast<ConditionalOperator>(E);
// Handle the GNU extension for missing LHS.
if (Expr *lhsExpr = C->getLHS())
if (DeclRefExpr *LHS = EvalVal(lhsExpr))
return LHS;
return EvalVal(C->getRHS());
}
// Accesses to members are potential references to data on the stack.
case Stmt::MemberExprClass: {
MemberExpr *M = cast<MemberExpr>(E);
// Check for indirect access. We only want direct field accesses.
if (!M->isArrow())
return EvalVal(M->getBase());
else
return NULL;
}
// Everything else: we simply don't reason about them.
default:
return NULL;
}
}
//===--- CHECK: Floating-Point comparisons (-Wfloat-equal) ---------------===//
/// Check for comparisons of floating point operands using != and ==.
/// Issue a warning if these are no self-comparisons, as they are not likely
/// to do what the programmer intended.
void Sema::CheckFloatComparison(SourceLocation loc, Expr* lex, Expr *rex) {
bool EmitWarning = true;
Expr* LeftExprSansParen = lex->IgnoreParens();
Expr* RightExprSansParen = rex->IgnoreParens();
// Special case: check for x == x (which is OK).
// Do not emit warnings for such cases.
if (DeclRefExpr* DRL = dyn_cast<DeclRefExpr>(LeftExprSansParen))
if (DeclRefExpr* DRR = dyn_cast<DeclRefExpr>(RightExprSansParen))
if (DRL->getDecl() == DRR->getDecl())
EmitWarning = false;
// Special case: check for comparisons against literals that can be exactly
// represented by APFloat. In such cases, do not emit a warning. This
// is a heuristic: often comparison against such literals are used to
// detect if a value in a variable has not changed. This clearly can
// lead to false negatives.
if (EmitWarning) {
if (FloatingLiteral* FLL = dyn_cast<FloatingLiteral>(LeftExprSansParen)) {
if (FLL->isExact())
EmitWarning = false;
} else
if (FloatingLiteral* FLR = dyn_cast<FloatingLiteral>(RightExprSansParen)){
if (FLR->isExact())
EmitWarning = false;
}
}
// Check for comparisons with builtin types.
if (EmitWarning)
if (CallExpr* CL = dyn_cast<CallExpr>(LeftExprSansParen))
if (CL->isBuiltinCall(Context))
EmitWarning = false;
if (EmitWarning)
if (CallExpr* CR = dyn_cast<CallExpr>(RightExprSansParen))
if (CR->isBuiltinCall(Context))
EmitWarning = false;
// Emit the diagnostic.
if (EmitWarning)
Diag(loc, diag::warn_floatingpoint_eq)
<< lex->getSourceRange() << rex->getSourceRange();
}
//===--- CHECK: Integer mixed-sign comparisons (-Wsign-compare) --------===//
//===--- CHECK: Lossy implicit conversions (-Wconversion) --------------===//
namespace {
/// Structure recording the 'active' range of an integer-valued
/// expression.
struct IntRange {
/// The number of bits active in the int.
unsigned Width;
/// True if the int is known not to have negative values.
bool NonNegative;
IntRange() {}
IntRange(unsigned Width, bool NonNegative)
: Width(Width), NonNegative(NonNegative)
{}
// Returns the range of the bool type.
static IntRange forBoolType() {
return IntRange(1, true);
}
// Returns the range of an integral type.
static IntRange forType(ASTContext &C, QualType T) {
return forCanonicalType(C, T->getCanonicalTypeInternal().getTypePtr());
}
// Returns the range of an integeral type based on its canonical
// representation.
static IntRange forCanonicalType(ASTContext &C, const Type *T) {
assert(T->isCanonicalUnqualified());
if (const VectorType *VT = dyn_cast<VectorType>(T))
T = VT->getElementType().getTypePtr();
if (const ComplexType *CT = dyn_cast<ComplexType>(T))
T = CT->getElementType().getTypePtr();
if (const EnumType *ET = dyn_cast<EnumType>(T))
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(const IntRange &L, const 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(const IntRange &L, const IntRange &R) {
return IntRange(std::min(L.Width, R.Width),
L.NonNegative || R.NonNegative);
}
};
IntRange GetValueRange(ASTContext &C, llvm::APSInt &value, unsigned MaxWidth) {
if (value.isSigned() && value.isNegative())
return IntRange(value.getMinSignedBits(), false);
if (value.getBitWidth() > MaxWidth)
value.trunc(MaxWidth);
// isNonNegative() just checks the sign bit without considering
// signedness.
return IntRange(value.getActiveBits(), true);
}
IntRange GetValueRange(ASTContext &C, APValue &result, QualType Ty,
unsigned MaxWidth) {
if (result.isInt())
return GetValueRange(C, result.getInt(), MaxWidth);
if (result.isVector()) {
IntRange R = GetValueRange(C, result.getVectorElt(0), Ty, MaxWidth);
for (unsigned i = 1, e = result.getVectorLength(); i != e; ++i) {
IntRange El = GetValueRange(C, result.getVectorElt(i), Ty, MaxWidth);
R = IntRange::join(R, El);
}
return R;
}
if (result.isComplexInt()) {
IntRange R = GetValueRange(C, result.getComplexIntReal(), MaxWidth);
IntRange I = GetValueRange(C, result.getComplexIntImag(), MaxWidth);
return IntRange::join(R, I);
}
// This can happen with lossless casts to intptr_t of "based" lvalues.
// Assume it might use arbitrary bits.
// FIXME: The only reason we need to pass the type in here is to get
// the sign right on this one case. It would be nice if APValue
// preserved this.
assert(result.isLValue());
return IntRange(MaxWidth, Ty->isUnsignedIntegerType());
}
/// Pseudo-evaluate the given integer expression, estimating the
/// range of values it might take.
///
/// \param MaxWidth - the width to which the value will be truncated
IntRange GetExprRange(ASTContext &C, Expr *E, unsigned MaxWidth) {
E = E->IgnoreParens();
// Try a full evaluation first.
Expr::EvalResult result;
if (E->Evaluate(result, C))
return GetValueRange(C, result.Val, E->getType(), MaxWidth);
// I think we only want to look through implicit casts here; if the
// user has an explicit widening cast, we should treat the value as
// being of the new, wider type.
if (ImplicitCastExpr *CE = dyn_cast<ImplicitCastExpr>(E)) {
if (CE->getCastKind() == CastExpr::CK_NoOp)
return GetExprRange(C, CE->getSubExpr(), MaxWidth);
IntRange OutputTypeRange = IntRange::forType(C, CE->getType());
bool isIntegerCast = (CE->getCastKind() == CastExpr::CK_IntegralCast);
if (!isIntegerCast && CE->getCastKind() == CastExpr::CK_Unknown)
isIntegerCast = CE->getSubExpr()->getType()->isIntegerType();
// Assume that non-integer casts can span the full range of the type.
if (!isIntegerCast)
return OutputTypeRange;
IntRange SubRange
= GetExprRange(C, CE->getSubExpr(),
std::min(MaxWidth, OutputTypeRange.Width));
// Bail out if the subexpr's range is as wide as the cast type.
if (SubRange.Width >= OutputTypeRange.Width)
return OutputTypeRange;
// Otherwise, we take the smaller width, and we're non-negative if
// either the output type or the subexpr is.
return IntRange(SubRange.Width,
SubRange.NonNegative || OutputTypeRange.NonNegative);
}
if (ConditionalOperator *CO = dyn_cast<ConditionalOperator>(E)) {
// If we can fold the condition, just take that operand.
bool CondResult;
if (CO->getCond()->EvaluateAsBooleanCondition(CondResult, C))
return GetExprRange(C, CondResult ? CO->getTrueExpr()
: CO->getFalseExpr(),
MaxWidth);
// Otherwise, conservatively merge.
IntRange L = GetExprRange(C, CO->getTrueExpr(), MaxWidth);
IntRange R = GetExprRange(C, CO->getFalseExpr(), MaxWidth);
return IntRange::join(L, R);
}
if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) {
switch (BO->getOpcode()) {
// Boolean-valued operations are single-bit and positive.
case BinaryOperator::LAnd:
case BinaryOperator::LOr:
case BinaryOperator::LT:
case BinaryOperator::GT:
case BinaryOperator::LE:
case BinaryOperator::GE:
case BinaryOperator::EQ:
case BinaryOperator::NE:
return IntRange::forBoolType();
// Operations with opaque sources are black-listed.
case BinaryOperator::PtrMemD:
case BinaryOperator::PtrMemI:
return IntRange::forType(C, E->getType());
// Bitwise-and uses the *infinum* of the two source ranges.
case BinaryOperator::And:
return IntRange::meet(GetExprRange(C, BO->getLHS(), MaxWidth),
GetExprRange(C, BO->getRHS(), MaxWidth));
// Left shift gets black-listed based on a judgement call.
case BinaryOperator::Shl:
return IntRange::forType(C, E->getType());
// Right shift by a constant can narrow its left argument.
case BinaryOperator::Shr: {
IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth);
// If the shift amount is a positive constant, drop the width by
// that much.
llvm::APSInt shift;
if (BO->getRHS()->isIntegerConstantExpr(shift, C) &&
shift.isNonNegative()) {
unsigned zext = shift.getZExtValue();
if (zext >= L.Width)
L.Width = (L.NonNegative ? 0 : 1);
else
L.Width -= zext;
}
return L;
}
// Comma acts as its right operand.
case BinaryOperator::Comma:
return GetExprRange(C, BO->getRHS(), MaxWidth);
// Black-list pointer subtractions.
case BinaryOperator::Sub:
if (BO->getLHS()->getType()->isPointerType())
return IntRange::forType(C, E->getType());
// fallthrough
default:
break;
}
// Treat every other operator as if it were closed on the
// narrowest type that encompasses both operands.
IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth);
IntRange R = GetExprRange(C, BO->getRHS(), MaxWidth);
return IntRange::join(L, R);
}
if (UnaryOperator *UO = dyn_cast<UnaryOperator>(E)) {
switch (UO->getOpcode()) {
// Boolean-valued operations are white-listed.
case UnaryOperator::LNot:
return IntRange::forBoolType();
// Operations with opaque sources are black-listed.
case UnaryOperator::Deref:
case UnaryOperator::AddrOf: // should be impossible
case UnaryOperator::OffsetOf:
return IntRange::forType(C, E->getType());
default:
return GetExprRange(C, UO->getSubExpr(), MaxWidth);
}
}
FieldDecl *BitField = E->getBitField();
if (BitField) {
llvm::APSInt BitWidthAP = BitField->getBitWidth()->EvaluateAsInt(C);
unsigned BitWidth = BitWidthAP.getZExtValue();
return IntRange(BitWidth, BitField->getType()->isUnsignedIntegerType());
}
return IntRange::forType(C, E->getType());
}
/// 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));
}
} // end anonymous namespace
/// \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 Equality whether this is an "equality-like" join, which
/// suppresses the warning in some cases
void Sema::CheckSignCompare(Expr *lex, Expr *rex, SourceLocation OpLoc,
const PartialDiagnostic &PD, bool Equality) {
// Don't warn if we're in an unevaluated context.
if (ExprEvalContexts.back().Context == Unevaluated)
return;
// If either expression is value-dependent, don't warn. We'll get another
// chance at instantiation time.
if (lex->isValueDependent() || rex->isValueDependent())
return;
QualType lt = lex->getType(), rt = rex->getType();
// Only warn if both operands are integral.
if (!lt->isIntegerType() || !rt->isIntegerType())
return;
// In C, the width of a bitfield determines its type, and the
// declared type only contributes the signedness. This duplicates
// the work that will later be done by UsualUnaryConversions.
// Eventually, this check will be reorganized in a way that avoids
// this duplication.
if (!getLangOptions().CPlusPlus) {
QualType tmp;
tmp = Context.isPromotableBitField(lex);
if (!tmp.isNull()) lt = tmp;
tmp = Context.isPromotableBitField(rex);
if (!tmp.isNull()) rt = tmp;
}
// The rule is that the signed operand becomes unsigned, so isolate the
// signed operand.
Expr *signedOperand = lex, *unsignedOperand = rex;
QualType signedType = lt, unsignedType = rt;
if (lt->isSignedIntegerType()) {
if (rt->isSignedIntegerType()) return;
} else {
if (!rt->isSignedIntegerType()) return;
std::swap(signedOperand, unsignedOperand);
std::swap(signedType, unsignedType);
}
unsigned unsignedWidth = Context.getIntWidth(unsignedType);
unsigned signedWidth = Context.getIntWidth(signedType);
// If the unsigned type is strictly smaller than the signed type,
// then (1) the result type will be signed and (2) the unsigned
// value will fit fully within the signed type, and thus the result
// of the comparison will be exact.
if (signedWidth > unsignedWidth)
return;
// Otherwise, calculate the effective ranges.
IntRange signedRange = GetExprRange(Context, signedOperand, signedWidth);
IntRange unsignedRange = GetExprRange(Context, unsignedOperand, unsignedWidth);
// We should never be unable to prove that the unsigned operand is
// non-negative.
assert(unsignedRange.NonNegative && "unsigned range includes negative?");
// If the signed operand is non-negative, then the signed->unsigned
// conversion won't change it.
if (signedRange.NonNegative)
return;
// 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 (Equality && unsignedRange.Width < unsignedWidth)
return;
Diag(OpLoc, PD)
<< lt << rt << lex->getSourceRange() << rex->getSourceRange();
}
/// Diagnose an implicit cast; purely a helper for CheckImplicitConversion.
static void DiagnoseImpCast(Sema &S, Expr *E, QualType T, unsigned diag) {
S.Diag(E->getExprLoc(), diag) << E->getType() << T << E->getSourceRange();
}
/// Implements -Wconversion.
void Sema::CheckImplicitConversion(Expr *E, QualType T) {
// Don't diagnose in unevaluated contexts.
if (ExprEvalContexts.back().Context == Sema::Unevaluated)
return;
// Don't diagnose for value-dependent expressions.
if (E->isValueDependent())
return;
const Type *Source = Context.getCanonicalType(E->getType()).getTypePtr();
const Type *Target = Context.getCanonicalType(T).getTypePtr();
// 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(*this, E, T, diag::warn_impcast_vector_scalar);
Source = cast<VectorType>(Source)->getElementType().getTypePtr();
Target = cast<VectorType>(Target)->getElementType().getTypePtr();
}
// Strip complex types.
if (isa<ComplexType>(Source)) {
if (!isa<ComplexType>(Target))
return DiagnoseImpCast(*this, E, T, diag::warn_impcast_complex_scalar);
Source = cast<ComplexType>(Source)->getElementType().getTypePtr();
Target = cast<ComplexType>(Target)->getElementType().getTypePtr();
}
const BuiltinType *SourceBT = dyn_cast<BuiltinType>(Source);
const BuiltinType *TargetBT = dyn_cast<BuiltinType>(Target);
// If the source is floating point...
if (SourceBT && SourceBT->isFloatingPoint()) {
// ...and the target is floating point...
if (TargetBT && TargetBT->isFloatingPoint()) {
// ...then warn if we're dropping FP rank.
// Builtin FP kinds are ordered by increasing FP rank.
if (SourceBT->getKind() > TargetBT->getKind()) {
// Don't warn about float constants that are precisely
// representable in the target type.
Expr::EvalResult result;
if (E->Evaluate(result, Context)) {
// Value might be a float, a float vector, or a float complex.
if (IsSameFloatAfterCast(result.Val,
Context.getFloatTypeSemantics(QualType(TargetBT, 0)),
Context.getFloatTypeSemantics(QualType(SourceBT, 0))))
return;
}
DiagnoseImpCast(*this, E, T, diag::warn_impcast_float_precision);
}
return;
}
// If the target is integral, always warn.
if ((TargetBT && TargetBT->isInteger()))
// TODO: don't warn for integer values?
return DiagnoseImpCast(*this, E, T, diag::warn_impcast_float_integer);
return;
}
if (!Source->isIntegerType() || !Target->isIntegerType())
return;
IntRange SourceRange = GetExprRange(Context, E, Context.getIntWidth(E->getType()));
IntRange TargetRange = IntRange::forCanonicalType(Context, Target);
// FIXME: also signed<->unsigned?
if (SourceRange.Width > TargetRange.Width) {
// People want to build with -Wshorten-64-to-32 and not -Wconversion
// and by god we'll let them.
if (SourceRange.Width == 64 && TargetRange.Width == 32)
return DiagnoseImpCast(*this, E, T, diag::warn_impcast_integer_64_32);
return DiagnoseImpCast(*this, E, T, diag::warn_impcast_integer_precision);
}
return;
}
// MarkLive - Mark all the blocks reachable from e as live. Returns the total
// number of blocks just marked live.
static unsigned MarkLive(CFGBlock *e, llvm::BitVector &live) {
unsigned count = 0;
std::queue<CFGBlock*> workq;
// Prep work queue
live.set(e->getBlockID());
++count;
workq.push(e);
// Solve
while (!workq.empty()) {
CFGBlock *item = workq.front();
workq.pop();
for (CFGBlock::succ_iterator I=item->succ_begin(),
E=item->succ_end();
I != E;
++I) {
if ((*I) && !live[(*I)->getBlockID()]) {
live.set((*I)->getBlockID());
++count;
workq.push(*I);
}
}
}
return count;
}
static SourceLocation GetUnreachableLoc(CFGBlock &b) {
Stmt *S;
if (!b.empty())
S = b[0].getStmt();
else if (b.getTerminator())
S = b.getTerminator();
else
return SourceLocation();
switch (S->getStmtClass()) {
case Expr::BinaryOperatorClass: {
if (b.size() < 2) {
CFGBlock *n = &b;
while (1) {
if (n->getTerminator())
return n->getTerminator()->getLocStart();
if (n->succ_size() != 1)
return SourceLocation();
n = n[0].succ_begin()[0];
if (n->pred_size() != 1)
return SourceLocation();
if (!n->empty())
return n[0][0].getStmt()->getLocStart();
}
}
return b[1].getStmt()->getLocStart();
}
case Stmt::CXXTryStmtClass: {
return cast<CXXTryStmt>(S)->getHandler(0)->getCatchLoc();
}
default: ;
}
return S->getLocStart();
}
static SourceLocation MarkLiveTop(CFGBlock *e, llvm::BitVector &live,
SourceManager &SM) {
std::queue<CFGBlock*> workq;
// Prep work queue
workq.push(e);
SourceLocation top = GetUnreachableLoc(*e);
bool FromMainFile = false;
bool FromSystemHeader = false;
bool TopValid = false;
if (top.isValid()) {
FromMainFile = SM.isFromMainFile(top);
FromSystemHeader = SM.isInSystemHeader(top);
TopValid = true;
}
// Solve
while (!workq.empty()) {
CFGBlock *item = workq.front();
workq.pop();
SourceLocation c = GetUnreachableLoc(*item);
if (c.isValid()
&& (!TopValid
|| (SM.isFromMainFile(c) && !FromMainFile)
|| (FromSystemHeader && !SM.isInSystemHeader(c))
|| SM.isBeforeInTranslationUnit(c, top))) {
top = c;
FromMainFile = SM.isFromMainFile(top);
FromSystemHeader = SM.isInSystemHeader(top);
}
live.set(item->getBlockID());
for (CFGBlock::succ_iterator I=item->succ_begin(),
E=item->succ_end();
I != E;
++I) {
if ((*I) && !live[(*I)->getBlockID()]) {
live.set((*I)->getBlockID());
workq.push(*I);
}
}
}
return top;
}
static int LineCmp(const void *p1, const void *p2) {
SourceLocation *Line1 = (SourceLocation *)p1;
SourceLocation *Line2 = (SourceLocation *)p2;
return !(*Line1 < *Line2);
}
/// CheckUnreachable - Check for unreachable code.
void Sema::CheckUnreachable(AnalysisContext &AC) {
unsigned count;
// We avoid checking when there are errors, as the CFG won't faithfully match
// the user's code.
if (getDiagnostics().hasErrorOccurred())
return;
if (Diags.getDiagnosticLevel(diag::warn_unreachable) == Diagnostic::Ignored)
return;
CFG *cfg = AC.getCFG();
if (cfg == 0)
return;
llvm::BitVector live(cfg->getNumBlockIDs());
// Mark all live things first.
count = MarkLive(&cfg->getEntry(), live);
if (count == cfg->getNumBlockIDs())
// If there are no dead blocks, we're done.
return;
llvm::SmallVector<SourceLocation, 24> lines;
bool AddEHEdges = AC.getAddEHEdges();
// First, give warnings for blocks with no predecessors, as they
// can't be part of a loop.
for (CFG::iterator I = cfg->begin(), E = cfg->end(); I != E; ++I) {
CFGBlock &b = **I;
if (!live[b.getBlockID()]) {
if (b.pred_begin() == b.pred_end()) {
if (!AddEHEdges && b.getTerminator()
&& isa<CXXTryStmt>(b.getTerminator())) {
// When not adding EH edges from calls, catch clauses
// can otherwise seem dead. Avoid noting them as dead.
count += MarkLive(&b, live);
continue;
}
SourceLocation c = GetUnreachableLoc(b);
if (!c.isValid()) {
// Blocks without a location can't produce a warning, so don't mark
// reachable blocks from here as live.
live.set(b.getBlockID());
++count;
continue;
}
lines.push_back(c);
// Avoid excessive errors by marking everything reachable from here
count += MarkLive(&b, live);
}
}
}
if (count < cfg->getNumBlockIDs()) {
// And then give warnings for the tops of loops.
for (CFG::iterator I = cfg->begin(), E = cfg->end(); I != E; ++I) {
CFGBlock &b = **I;
if (!live[b.getBlockID()])
// Avoid excessive errors by marking everything reachable from here
lines.push_back(MarkLiveTop(&b, live, Context.getSourceManager()));
}
}
llvm::array_pod_sort(lines.begin(), lines.end(), LineCmp);
for (llvm::SmallVector<SourceLocation, 24>::iterator I = lines.begin(),
E = lines.end();
I != E;
++I)
if (I->isValid())
Diag(*I, diag::warn_unreachable);
}
/// CheckFallThrough - Check that we don't fall off the end of a
/// Statement that should return a value.
///
/// \returns AlwaysFallThrough iff we always fall off the end of the statement,
/// MaybeFallThrough iff we might or might not fall off the end,
/// NeverFallThroughOrReturn iff we never fall off the end of the statement or
/// return. We assume NeverFallThrough iff we never fall off the end of the
/// statement but we may return. We assume that functions not marked noreturn
/// will return.
Sema::ControlFlowKind Sema::CheckFallThrough(AnalysisContext &AC) {
CFG *cfg = AC.getCFG();
if (cfg == 0)
// FIXME: This should be NeverFallThrough
return NeverFallThroughOrReturn;
// The CFG leaves in dead things, and we don't want the dead code paths to
// confuse us, so we mark all live things first.
std::queue<CFGBlock*> workq;
llvm::BitVector live(cfg->getNumBlockIDs());
unsigned count = MarkLive(&cfg->getEntry(), live);
bool AddEHEdges = AC.getAddEHEdges();
if (!AddEHEdges && count != cfg->getNumBlockIDs())
// When there are things remaining dead, and we didn't add EH edges
// from CallExprs to the catch clauses, we have to go back and
// mark them as live.
for (CFG::iterator I = cfg->begin(), E = cfg->end(); I != E; ++I) {
CFGBlock &b = **I;
if (!live[b.getBlockID()]) {
if (b.pred_begin() == b.pred_end()) {
if (b.getTerminator() && isa<CXXTryStmt>(b.getTerminator()))
// When not adding EH edges from calls, catch clauses
// can otherwise seem dead. Avoid noting them as dead.
count += MarkLive(&b, live);
continue;
}
}
}
// Now we know what is live, we check the live precessors of the exit block
// and look for fall through paths, being careful to ignore normal returns,
// and exceptional paths.
bool HasLiveReturn = false;
bool HasFakeEdge = false;
bool HasPlainEdge = false;
bool HasAbnormalEdge = false;
for (CFGBlock::pred_iterator I=cfg->getExit().pred_begin(),
E = cfg->getExit().pred_end();
I != E;
++I) {
CFGBlock& B = **I;
if (!live[B.getBlockID()])
continue;
if (B.size() == 0) {
if (B.getTerminator() && isa<CXXTryStmt>(B.getTerminator())) {
HasAbnormalEdge = true;
continue;
}
// A labeled empty statement, or the entry block...
HasPlainEdge = true;
continue;
}
Stmt *S = B[B.size()-1];
if (isa<ReturnStmt>(S)) {
HasLiveReturn = true;
continue;
}
if (isa<ObjCAtThrowStmt>(S)) {
HasFakeEdge = true;
continue;
}
if (isa<CXXThrowExpr>(S)) {
HasFakeEdge = true;
continue;
}
if (const AsmStmt *AS = dyn_cast<AsmStmt>(S)) {
if (AS->isMSAsm()) {
HasFakeEdge = true;
HasLiveReturn = true;
continue;
}
}
if (isa<CXXTryStmt>(S)) {
HasAbnormalEdge = true;
continue;
}
bool NoReturnEdge = false;
if (CallExpr *C = dyn_cast<CallExpr>(S)) {
if (B.succ_begin()[0] != &cfg->getExit()) {
HasAbnormalEdge = true;
continue;
}
Expr *CEE = C->getCallee()->IgnoreParenCasts();
if (CEE->getType().getNoReturnAttr()) {
NoReturnEdge = true;
HasFakeEdge = true;
} else if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(CEE)) {
ValueDecl *VD = DRE->getDecl();
if (VD->hasAttr<NoReturnAttr>()) {
NoReturnEdge = true;
HasFakeEdge = true;
}
}
}
// FIXME: Add noreturn message sends.
if (NoReturnEdge == false)
HasPlainEdge = true;
}
if (!HasPlainEdge) {
if (HasLiveReturn)
return NeverFallThrough;
return NeverFallThroughOrReturn;
}
if (HasAbnormalEdge || HasFakeEdge || HasLiveReturn)
return MaybeFallThrough;
// This says AlwaysFallThrough for calls to functions that are not marked
// noreturn, that don't return. If people would like this warning to be more
// accurate, such functions should be marked as noreturn.
return AlwaysFallThrough;
}
/// CheckFallThroughForFunctionDef - Check that we don't fall off the end of a
/// function that should return a value. Check that we don't fall off the end
/// of a noreturn function. We assume that functions and blocks not marked
/// noreturn will return.
void Sema::CheckFallThroughForFunctionDef(Decl *D, Stmt *Body,
AnalysisContext &AC) {
// FIXME: Would be nice if we had a better way to control cascading errors,
// but for now, avoid them. The problem is that when Parse sees:
// int foo() { return a; }
// The return is eaten and the Sema code sees just:
// int foo() { }
// which this code would then warn about.
if (getDiagnostics().hasErrorOccurred())
return;
bool ReturnsVoid = false;
bool HasNoReturn = false;
if (FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
// If the result type of the function is a dependent type, we don't know
// whether it will be void or not, so don't
if (FD->getResultType()->isDependentType())
return;
if (FD->getResultType()->isVoidType())
ReturnsVoid = true;
if (FD->hasAttr<NoReturnAttr>())
HasNoReturn = true;
} else if (ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(D)) {
if (MD->getResultType()->isVoidType())
ReturnsVoid = true;
if (MD->hasAttr<NoReturnAttr>())
HasNoReturn = true;
}
// Short circuit for compilation speed.
if ((Diags.getDiagnosticLevel(diag::warn_maybe_falloff_nonvoid_function)
== Diagnostic::Ignored || ReturnsVoid)
&& (Diags.getDiagnosticLevel(diag::warn_noreturn_function_has_return_expr)
== Diagnostic::Ignored || !HasNoReturn)
&& (Diags.getDiagnosticLevel(diag::warn_suggest_noreturn_block)
== Diagnostic::Ignored || !ReturnsVoid))
return;
// FIXME: Function try block
if (CompoundStmt *Compound = dyn_cast<CompoundStmt>(Body)) {
switch (CheckFallThrough(AC)) {
case MaybeFallThrough:
if (HasNoReturn)
Diag(Compound->getRBracLoc(), diag::warn_falloff_noreturn_function);
else if (!ReturnsVoid)
Diag(Compound->getRBracLoc(),diag::warn_maybe_falloff_nonvoid_function);
break;
case AlwaysFallThrough:
if (HasNoReturn)
Diag(Compound->getRBracLoc(), diag::warn_falloff_noreturn_function);
else if (!ReturnsVoid)
Diag(Compound->getRBracLoc(), diag::warn_falloff_nonvoid_function);
break;
case NeverFallThroughOrReturn:
if (ReturnsVoid && !HasNoReturn)
Diag(Compound->getLBracLoc(), diag::warn_suggest_noreturn_function);
break;
case NeverFallThrough:
break;
}
}
}
/// CheckFallThroughForBlock - Check that we don't fall off the end of a block
/// that should return a value. Check that we don't fall off the end of a
/// noreturn block. We assume that functions and blocks not marked noreturn
/// will return.
void Sema::CheckFallThroughForBlock(QualType BlockTy, Stmt *Body,
AnalysisContext &AC) {
// FIXME: Would be nice if we had a better way to control cascading errors,
// but for now, avoid them. The problem is that when Parse sees:
// int foo() { return a; }
// The return is eaten and the Sema code sees just:
// int foo() { }
// which this code would then warn about.
if (getDiagnostics().hasErrorOccurred())
return;
bool ReturnsVoid = false;
bool HasNoReturn = false;
if (const FunctionType *FT =BlockTy->getPointeeType()->getAs<FunctionType>()){
if (FT->getResultType()->isVoidType())
ReturnsVoid = true;
if (FT->getNoReturnAttr())
HasNoReturn = true;
}
// Short circuit for compilation speed.
if (ReturnsVoid
&& !HasNoReturn
&& (Diags.getDiagnosticLevel(diag::warn_suggest_noreturn_block)
== Diagnostic::Ignored || !ReturnsVoid))
return;
// FIXME: Funtion try block
if (CompoundStmt *Compound = dyn_cast<CompoundStmt>(Body)) {
switch (CheckFallThrough(AC)) {
case MaybeFallThrough:
if (HasNoReturn)
Diag(Compound->getRBracLoc(), diag::err_noreturn_block_has_return_expr);
else if (!ReturnsVoid)
Diag(Compound->getRBracLoc(), diag::err_maybe_falloff_nonvoid_block);
break;
case AlwaysFallThrough:
if (HasNoReturn)
Diag(Compound->getRBracLoc(), diag::err_noreturn_block_has_return_expr);
else if (!ReturnsVoid)
Diag(Compound->getRBracLoc(), diag::err_falloff_nonvoid_block);
break;
case NeverFallThroughOrReturn:
if (ReturnsVoid)
Diag(Compound->getLBracLoc(), diag::warn_suggest_noreturn_block);
break;
case NeverFallThrough:
break;
}
}
}
/// CheckParmsForFunctionDef - Check that the parameters of the given
/// function are appropriate for the definition of a function. This
/// takes care of any checks that cannot be performed on the
/// declaration itself, e.g., that the types of each of the function
/// parameters are complete.
bool Sema::CheckParmsForFunctionDef(FunctionDecl *FD) {
bool HasInvalidParm = false;
for (unsigned p = 0, NumParams = FD->getNumParams(); p < NumParams; ++p) {
ParmVarDecl *Param = FD->getParamDecl(p);
// C99 6.7.5.3p4: the parameters in a parameter type list in a
// function declarator that is part of a function definition of
// that function shall not have incomplete type.
//
// This is also C++ [dcl.fct]p6.
if (!Param->isInvalidDecl() &&
RequireCompleteType(Param->getLocation(), Param->getType(),
diag::err_typecheck_decl_incomplete_type)) {
Param->setInvalidDecl();
HasInvalidParm = true;
}
// C99 6.9.1p5: If the declarator includes a parameter type list, the
// declaration of each parameter shall include an identifier.
if (Param->getIdentifier() == 0 &&
!Param->isImplicit() &&
!getLangOptions().CPlusPlus)
Diag(Param->getLocation(), diag::err_parameter_name_omitted);
}
return HasInvalidParm;
}