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   MR = MR->StripCasts();
48 
49   DefinedOrUnknownSVal Size = getDynamicExtent(State, MR, SVB);
50   SVal ElementSize = getElementExtent(ElementTy, SVB);
51 
52   SVal ElementCount =
53       SVB.evalBinOp(State, BO_Div, Size, ElementSize, SVB.getArrayIndexType());
54 
55   return ElementCount.castAs<DefinedOrUnknownSVal>();
56 }
57 
58 SVal getDynamicExtentWithOffset(ProgramStateRef State, SVal BufV) {
59   SValBuilder &SvalBuilder = State->getStateManager().getSValBuilder();
60   const MemRegion *MRegion = BufV.getAsRegion();
61   if (!MRegion)
62     return UnknownVal();
63   RegionOffset Offset = MRegion->getAsOffset();
64   if (Offset.hasSymbolicOffset())
65     return UnknownVal();
66   const MemRegion *BaseRegion = MRegion->getBaseRegion();
67   if (!BaseRegion)
68     return UnknownVal();
69 
70   NonLoc OffsetInBytes = SvalBuilder.makeArrayIndex(
71       Offset.getOffset() /
72       MRegion->getMemRegionManager().getContext().getCharWidth());
73   DefinedOrUnknownSVal ExtentInBytes =
74       getDynamicExtent(State, BaseRegion, SvalBuilder);
75 
76   return SvalBuilder.evalBinOp(State, BinaryOperator::Opcode::BO_Sub,
77                                ExtentInBytes, OffsetInBytes,
78                                SvalBuilder.getArrayIndexType());
79 }
80 
81 ProgramStateRef setDynamicExtent(ProgramStateRef State, const MemRegion *MR,
82                                  DefinedOrUnknownSVal Size, SValBuilder &SVB) {
83   MR = MR->StripCasts();
84 
85   if (Size.isUnknown())
86     return State;
87 
88   return State->set<DynamicExtentMap>(MR->StripCasts(), Size);
89 }
90 
91 } // namespace ento
92 } // namespace clang
93