bool Sema::ActOnSuperScopeSpecifier(SourceLocation SuperLoc,
SourceLocation ColonColonLoc,
CXXScopeSpec &SS) {
CXXRecordDecl *RD = nullptr;
for (Scope *S = getCurScope(); S; S = S->getParent()) {
if (S->isFunctionScope()) {
if (CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(S->getEntity()))
RD = MD->getParent();
break;
}
if (S->isClassScope()) {
RD = cast<CXXRecordDecl>(S->getEntity());
break;
}
}
if (!RD) {
Diag(SuperLoc, diag::err_invalid_super_scope);
return true;
} else if (RD->isLambda()) {
Diag(SuperLoc, diag::err_super_in_lambda_unsupported);
return true;
} else if (RD->getNumBases() == 0) {
Diag(SuperLoc, diag::err_no_base_classes) << RD->getName();
return true;
}
SS.MakeSuper(Context, RD, SuperLoc, ColonColonLoc);
return false;
}
/// Create a fake body for std::call_once.
/// Emulates the following function body:
///
/// \code
/// typedef struct once_flag_s {
/// unsigned long __state = 0;
/// } once_flag;
/// template<class Callable>
/// void call_once(once_flag& o, Callable func) {
/// if (!o.__state) {
/// func();
/// }
/// o.__state = 1;
/// }
/// \endcode
static Stmt *create_call_once(ASTContext &C, const FunctionDecl *D) {
DEBUG(llvm::dbgs() << "Generating body for call_once\n");
// We need at least two parameters.
if (D->param_size() < 2)
return nullptr;
ASTMaker M(C);
const ParmVarDecl *Flag = D->getParamDecl(0);
const ParmVarDecl *Callback = D->getParamDecl(1);
if (!Callback->getType()->isReferenceType()) {
llvm::dbgs() << "libcxx03 std::call_once implementation, skipping.\n";
return nullptr;
}
if (!Flag->getType()->isReferenceType()) {
llvm::dbgs() << "unknown std::call_once implementation, skipping.\n";
return nullptr;
}
QualType CallbackType = Callback->getType().getNonReferenceType();
// Nullable pointer, non-null iff function is a CXXRecordDecl.
CXXRecordDecl *CallbackRecordDecl = CallbackType->getAsCXXRecordDecl();
QualType FlagType = Flag->getType().getNonReferenceType();
auto *FlagRecordDecl = dyn_cast_or_null<RecordDecl>(FlagType->getAsTagDecl());
if (!FlagRecordDecl) {
DEBUG(llvm::dbgs() << "Flag field is not a record: "
<< "unknown std::call_once implementation, "
<< "ignoring the call.\n");
return nullptr;
}
// We initially assume libc++ implementation of call_once,
// where the once_flag struct has a field `__state_`.
ValueDecl *FlagFieldDecl = M.findMemberField(FlagRecordDecl, "__state_");
// Otherwise, try libstdc++ implementation, with a field
// `_M_once`
if (!FlagFieldDecl) {
FlagFieldDecl = M.findMemberField(FlagRecordDecl, "_M_once");
}
if (!FlagFieldDecl) {
DEBUG(llvm::dbgs() << "No field _M_once or __state_ found on "
<< "std::once_flag struct: unknown std::call_once "
<< "implementation, ignoring the call.");
return nullptr;
}
bool isLambdaCall = CallbackRecordDecl && CallbackRecordDecl->isLambda();
if (CallbackRecordDecl && !isLambdaCall) {
DEBUG(llvm::dbgs() << "Not supported: synthesizing body for functors when "
<< "body farming std::call_once, ignoring the call.");
return nullptr;
}
SmallVector<Expr *, 5> CallArgs;
const FunctionProtoType *CallbackFunctionType;
if (isLambdaCall) {
// Lambda requires callback itself inserted as a first parameter.
CallArgs.push_back(
M.makeDeclRefExpr(Callback,
/* RefersToEnclosingVariableOrCapture=*/ true));
CallbackFunctionType = CallbackRecordDecl->getLambdaCallOperator()
->getType()
->getAs<FunctionProtoType>();
} else if (!CallbackType->getPointeeType().isNull()) {
CallbackFunctionType =
CallbackType->getPointeeType()->getAs<FunctionProtoType>();
} else {
CallbackFunctionType = CallbackType->getAs<FunctionProtoType>();
}
if (!CallbackFunctionType)
return nullptr;
// First two arguments are used for the flag and for the callback.
if (D->getNumParams() != CallbackFunctionType->getNumParams() + 2) {
DEBUG(llvm::dbgs() << "Types of params of the callback do not match "
<< "params passed to std::call_once, "
<< "ignoring the call\n");
return nullptr;
}
// All arguments past first two ones are passed to the callback,
// and we turn lvalues into rvalues if the argument is not passed by
// reference.
for (unsigned int ParamIdx = 2; ParamIdx < D->getNumParams(); ParamIdx++) {
const ParmVarDecl *PDecl = D->getParamDecl(ParamIdx);
Expr *ParamExpr = M.makeDeclRefExpr(PDecl);
if (!CallbackFunctionType->getParamType(ParamIdx - 2)->isReferenceType()) {
QualType PTy = PDecl->getType().getNonReferenceType();
ParamExpr = M.makeLvalueToRvalue(ParamExpr, PTy);
}
CallArgs.push_back(ParamExpr);
}
CallExpr *CallbackCall;
if (isLambdaCall) {
CallbackCall = create_call_once_lambda_call(C, M, Callback,
CallbackRecordDecl, CallArgs);
} else {
// Function pointer case.
CallbackCall = create_call_once_funcptr_call(C, M, Callback, CallArgs);
}
DeclRefExpr *FlagDecl =
M.makeDeclRefExpr(Flag,
/* RefersToEnclosingVariableOrCapture=*/true);
MemberExpr *Deref = M.makeMemberExpression(FlagDecl, FlagFieldDecl);
assert(Deref->isLValue());
QualType DerefType = Deref->getType();
// Negation predicate.
UnaryOperator *FlagCheck = new (C) UnaryOperator(
/* input=*/
M.makeImplicitCast(M.makeLvalueToRvalue(Deref, DerefType), DerefType,
CK_IntegralToBoolean),
/* opc=*/ UO_LNot,
/* QualType=*/ C.IntTy,
/* ExprValueKind=*/ VK_RValue,
/* ExprObjectKind=*/ OK_Ordinary, SourceLocation());
// Create assignment.
BinaryOperator *FlagAssignment = M.makeAssignment(
Deref, M.makeIntegralCast(M.makeIntegerLiteral(1, C.IntTy), DerefType),
DerefType);
IfStmt *Out = new (C)
IfStmt(C, SourceLocation(),
/* IsConstexpr=*/ false,
/* init=*/ nullptr,
/* var=*/ nullptr,
/* cond=*/ FlagCheck,
/* then=*/ M.makeCompound({CallbackCall, FlagAssignment}));
return Out;
}