1 //=======- ASTUtils.cpp ------------------------------------------*- C++ -*-==//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #include "ASTUtils.h"
10 #include "PtrTypesSemantics.h"
11 #include "clang/AST/CXXInheritance.h"
12 #include "clang/AST/Decl.h"
13 #include "clang/AST/DeclCXX.h"
14 #include "clang/AST/ExprCXX.h"
15 #include <optional>
16 
17 namespace clang {
18 
19 std::pair<const Expr *, bool>
tryToFindPtrOrigin(const Expr * E,bool StopAtFirstRefCountedObj)20 tryToFindPtrOrigin(const Expr *E, bool StopAtFirstRefCountedObj) {
21   while (E) {
22     if (auto *cast = dyn_cast<CastExpr>(E)) {
23       if (StopAtFirstRefCountedObj) {
24         if (auto *ConversionFunc =
25                 dyn_cast_or_null<FunctionDecl>(cast->getConversionFunction())) {
26           if (isCtorOfRefCounted(ConversionFunc))
27             return {E, true};
28         }
29       }
30       // FIXME: This can give false "origin" that would lead to false negatives
31       // in checkers. See https://reviews.llvm.org/D37023 for reference.
32       E = cast->getSubExpr();
33       continue;
34     }
35     if (auto *call = dyn_cast<CallExpr>(E)) {
36       if (auto *memberCall = dyn_cast<CXXMemberCallExpr>(call)) {
37         std::optional<bool> IsGetterOfRefCt = isGetterOfRefCounted(memberCall->getMethodDecl());
38         if (IsGetterOfRefCt && *IsGetterOfRefCt) {
39           E = memberCall->getImplicitObjectArgument();
40           if (StopAtFirstRefCountedObj) {
41             return {E, true};
42           }
43           continue;
44         }
45       }
46 
47       if (auto *operatorCall = dyn_cast<CXXOperatorCallExpr>(E)) {
48         if (operatorCall->getNumArgs() == 1) {
49           E = operatorCall->getArg(0);
50           continue;
51         }
52       }
53 
54       if (auto *callee = call->getDirectCallee()) {
55         if (isCtorOfRefCounted(callee)) {
56           if (StopAtFirstRefCountedObj)
57             return {E, true};
58 
59           E = call->getArg(0);
60           continue;
61         }
62 
63         if (isPtrConversion(callee)) {
64           E = call->getArg(0);
65           continue;
66         }
67       }
68     }
69     if (auto *unaryOp = dyn_cast<UnaryOperator>(E)) {
70       // FIXME: Currently accepts ANY unary operator. Is it OK?
71       E = unaryOp->getSubExpr();
72       continue;
73     }
74 
75     break;
76   }
77   // Some other expression.
78   return {E, false};
79 }
80 
isASafeCallArg(const Expr * E)81 bool isASafeCallArg(const Expr *E) {
82   assert(E);
83   if (auto *Ref = dyn_cast<DeclRefExpr>(E)) {
84     if (auto *D = dyn_cast_or_null<VarDecl>(Ref->getFoundDecl())) {
85       if (isa<ParmVarDecl>(D) || D->isLocalVarDecl())
86         return true;
87     }
88   }
89 
90   // TODO: checker for method calls on non-refcounted objects
91   return isa<CXXThisExpr>(E);
92 }
93 
94 } // namespace clang
95