1 //===- DynamicExtent.cpp - Dynamic extent related APIs ----------*- 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 //  This file defines APIs that track and query dynamic extent information.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "clang/StaticAnalyzer/Core/PathSensitive/DynamicExtent.h"
14 #include "clang/AST/Expr.h"
15 #include "clang/Basic/LLVM.h"
16 #include "clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h"
17 #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
18 #include "clang/StaticAnalyzer/Core/PathSensitive/SValBuilder.h"
19 #include "clang/StaticAnalyzer/Core/PathSensitive/SVals.h"
20 #include "clang/StaticAnalyzer/Core/PathSensitive/SymbolManager.h"
21 
22 REGISTER_MAP_WITH_PROGRAMSTATE(DynamicExtentMap, const clang::ento::MemRegion *,
23                                clang::ento::DefinedOrUnknownSVal)
24 
25 namespace clang {
26 namespace ento {
27 
28 DefinedOrUnknownSVal getDynamicExtent(ProgramStateRef State,
29                                       const MemRegion *MR, SValBuilder &SVB) {
30   MR = MR->StripCasts();
31 
32   if (const DefinedOrUnknownSVal *Size = State->get<DynamicExtentMap>(MR))
33     return *Size;
34 
35   return MR->getMemRegionManager().getStaticSize(MR, SVB);
36 }
37 
38 DefinedOrUnknownSVal getElementExtent(QualType Ty, SValBuilder &SVB) {
39   return SVB.makeIntVal(SVB.getContext().getTypeSizeInChars(Ty).getQuantity(),
40                         SVB.getArrayIndexType());
41 }
42 
43 DefinedOrUnknownSVal getDynamicElementCount(ProgramStateRef State,
44                                             const MemRegion *MR,
45                                             SValBuilder &SVB,
46                                             QualType ElementTy) {
47   assert(MR != nullptr && "Not-null region expected");
48   MR = MR->StripCasts();
49 
50   DefinedOrUnknownSVal Size = getDynamicExtent(State, MR, SVB);
51   SVal ElementSize = getElementExtent(ElementTy, SVB);
52 
53   SVal ElementCount =
54       SVB.evalBinOp(State, BO_Div, Size, ElementSize, SVB.getArrayIndexType());
55 
56   return ElementCount.castAs<DefinedOrUnknownSVal>();
57 }
58 
59 SVal getDynamicExtentWithOffset(ProgramStateRef State, SVal BufV) {
60   SValBuilder &SvalBuilder = State->getStateManager().getSValBuilder();
61   const MemRegion *MRegion = BufV.getAsRegion();
62   if (!MRegion)
63     return UnknownVal();
64   RegionOffset Offset = MRegion->getAsOffset();
65   if (Offset.hasSymbolicOffset())
66     return UnknownVal();
67   const MemRegion *BaseRegion = MRegion->getBaseRegion();
68   if (!BaseRegion)
69     return UnknownVal();
70 
71   NonLoc OffsetInBytes = SvalBuilder.makeArrayIndex(
72       Offset.getOffset() /
73       MRegion->getMemRegionManager().getContext().getCharWidth());
74   DefinedOrUnknownSVal ExtentInBytes =
75       getDynamicExtent(State, BaseRegion, SvalBuilder);
76 
77   return SvalBuilder.evalBinOp(State, BinaryOperator::Opcode::BO_Sub,
78                                ExtentInBytes, OffsetInBytes,
79                                SvalBuilder.getArrayIndexType());
80 }
81 
82 ProgramStateRef setDynamicExtent(ProgramStateRef State, const MemRegion *MR,
83                                  DefinedOrUnknownSVal Size, SValBuilder &SVB) {
84   MR = MR->StripCasts();
85 
86   if (Size.isUnknown())
87     return State;
88 
89   return State->set<DynamicExtentMap>(MR->StripCasts(), Size);
90 }
91 
92 } // namespace ento
93 } // namespace clang
94