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//=======- ASTUtils.cpp ------------------------------------------*- C++ -*-==//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "ASTUtils.h"
#include "PtrTypesSemantics.h"
#include "clang/AST/CXXInheritance.h"
#include "clang/AST/Decl.h"
#include "clang/AST/DeclCXX.h"
#include "clang/AST/ExprCXX.h"
#include "clang/AST/ExprObjC.h"
#include "clang/AST/StmtVisitor.h"
#include <optional>
namespace clang {
bool isSafePtr(clang::CXXRecordDecl *Decl) {
return isRefCounted(Decl) || isCheckedPtr(Decl);
}
bool tryToFindPtrOrigin(
const Expr *E, bool StopAtFirstRefCountedObj,
std::function<bool(const clang::Expr *, bool)> callback) {
while (E) {
if (auto *tempExpr = dyn_cast<MaterializeTemporaryExpr>(E)) {
E = tempExpr->getSubExpr();
continue;
}
if (auto *tempExpr = dyn_cast<CXXBindTemporaryExpr>(E)) {
E = tempExpr->getSubExpr();
continue;
}
if (auto *tempExpr = dyn_cast<CXXConstructExpr>(E)) {
if (auto *C = tempExpr->getConstructor()) {
if (auto *Class = C->getParent(); Class && isSafePtr(Class))
return callback(E, true);
break;
}
}
if (auto *POE = dyn_cast<PseudoObjectExpr>(E)) {
if (auto *RF = POE->getResultExpr()) {
E = RF;
continue;
}
}
if (auto *tempExpr = dyn_cast<ParenExpr>(E)) {
E = tempExpr->getSubExpr();
continue;
}
if (auto *Expr = dyn_cast<ConditionalOperator>(E)) {
return tryToFindPtrOrigin(Expr->getTrueExpr(), StopAtFirstRefCountedObj,
callback) &&
tryToFindPtrOrigin(Expr->getFalseExpr(), StopAtFirstRefCountedObj,
callback);
}
if (auto *cast = dyn_cast<CastExpr>(E)) {
if (StopAtFirstRefCountedObj) {
if (auto *ConversionFunc =
dyn_cast_or_null<FunctionDecl>(cast->getConversionFunction())) {
if (isCtorOfSafePtr(ConversionFunc))
return callback(E, true);
}
}
// FIXME: This can give false "origin" that would lead to false negatives
// in checkers. See https://reviews.llvm.org/D37023 for reference.
E = cast->getSubExpr();
continue;
}
if (auto *call = dyn_cast<CallExpr>(E)) {
if (auto *memberCall = dyn_cast<CXXMemberCallExpr>(call)) {
if (auto *decl = memberCall->getMethodDecl()) {
std::optional<bool> IsGetterOfRefCt = isGetterOfSafePtr(decl);
if (IsGetterOfRefCt && *IsGetterOfRefCt) {
E = memberCall->getImplicitObjectArgument();
if (StopAtFirstRefCountedObj) {
return callback(E, true);
}
continue;
}
}
}
if (auto *operatorCall = dyn_cast<CXXOperatorCallExpr>(E)) {
if (operatorCall->getNumArgs() == 1) {
E = operatorCall->getArg(0);
continue;
}
}
if (auto *callee = call->getDirectCallee()) {
if (isCtorOfRefCounted(callee) || isCtorOfCheckedPtr(callee)) {
if (StopAtFirstRefCountedObj)
return callback(E, true);
E = call->getArg(0);
continue;
}
if (isSafePtrType(callee->getReturnType()))
return callback(E, true);
if (isSingleton(callee))
return callback(E, true);
if (callee->isInStdNamespace() && safeGetName(callee) == "forward") {
E = call->getArg(0);
continue;
}
if (isPtrConversion(callee)) {
E = call->getArg(0);
continue;
}
}
}
if (auto *ObjCMsgExpr = dyn_cast<ObjCMessageExpr>(E)) {
if (auto *Method = ObjCMsgExpr->getMethodDecl()) {
if (isSafePtrType(Method->getReturnType()))
return callback(E, true);
}
}
if (auto *unaryOp = dyn_cast<UnaryOperator>(E)) {
// FIXME: Currently accepts ANY unary operator. Is it OK?
E = unaryOp->getSubExpr();
continue;
}
break;
}
// Some other expression.
return callback(E, false);
}
bool isASafeCallArg(const Expr *E) {
assert(E);
if (auto *Ref = dyn_cast<DeclRefExpr>(E)) {
if (auto *D = dyn_cast_or_null<VarDecl>(Ref->getFoundDecl())) {
if (isa<ParmVarDecl>(D) || D->isLocalVarDecl())
return true;
}
}
if (isConstOwnerPtrMemberExpr(E))
return true;
// TODO: checker for method calls on non-refcounted objects
return isa<CXXThisExpr>(E);
}
bool isConstOwnerPtrMemberExpr(const clang::Expr *E) {
if (auto *MCE = dyn_cast<CXXMemberCallExpr>(E)) {
if (auto *Callee = MCE->getDirectCallee()) {
auto Name = safeGetName(Callee);
if (Name == "get" || Name == "ptr") {
auto *ThisArg = MCE->getImplicitObjectArgument();
E = ThisArg;
}
}
} else if (auto *OCE = dyn_cast<CXXOperatorCallExpr>(E)) {
if (OCE->getOperator() == OO_Star && OCE->getNumArgs() == 1)
E = OCE->getArg(0);
}
auto *ME = dyn_cast<MemberExpr>(E);
if (!ME)
return false;
auto *D = ME->getMemberDecl();
if (!D)
return false;
auto T = D->getType();
return isOwnerPtrType(T) && T.isConstQualified();
}
class EnsureFunctionVisitor
: public ConstStmtVisitor<EnsureFunctionVisitor, bool> {
public:
bool VisitStmt(const Stmt *S) {
for (const Stmt *Child : S->children()) {
if (Child && !Visit(Child))
return false;
}
return true;
}
bool VisitReturnStmt(const ReturnStmt *RS) {
if (auto *RV = RS->getRetValue()) {
RV = RV->IgnoreParenCasts();
if (isa<CXXNullPtrLiteralExpr>(RV))
return true;
return isConstOwnerPtrMemberExpr(RV);
}
return false;
}
};
bool EnsureFunctionAnalysis::isACallToEnsureFn(const clang::Expr *E) const {
auto *MCE = dyn_cast<CXXMemberCallExpr>(E);
if (!MCE)
return false;
auto *Callee = MCE->getDirectCallee();
if (!Callee)
return false;
auto *Body = Callee->getBody();
if (!Body)
return false;
auto [CacheIt, IsNew] = Cache.insert(std::make_pair(Callee, false));
if (IsNew)
CacheIt->second = EnsureFunctionVisitor().Visit(Body);
return CacheIt->second;
}
} // namespace clang
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