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
22REGISTER_MAP_WITH_PROGRAMSTATE(DynamicExtentMap, const clang::ento::MemRegion *,
23 clang::ento::DefinedOrUnknownSVal)
24
25namespace clang {
26namespace ento {
27
28DefinedOrUnknownSVal getDynamicExtent(ProgramStateRef State,
29 const MemRegion *MR, SValBuilder &SVB) {
30 MR = MR->StripCasts();
31
32 if (const DefinedOrUnknownSVal *Size = State->get<DynamicExtentMap>(key: MR))
33 if (auto SSize =
34 SVB.convertToArrayIndex(val: *Size).getAs<DefinedOrUnknownSVal>())
35 return *SSize;
36
37 return MR->getMemRegionManager().getStaticSize(MR, SVB);
38}
39
40DefinedOrUnknownSVal getElementExtent(QualType Ty, SValBuilder &SVB) {
41 return SVB.makeIntVal(integer: SVB.getContext().getTypeSizeInChars(T: Ty).getQuantity(),
42 type: SVB.getArrayIndexType());
43}
44
45static DefinedOrUnknownSVal getConstantArrayElementCount(SValBuilder &SVB,
46 const MemRegion *MR) {
47 MR = MR->StripCasts();
48
49 const auto *TVR = MR->getAs<TypedValueRegion>();
50 if (!TVR)
51 return UnknownVal();
52
53 if (const ConstantArrayType *CAT =
54 SVB.getContext().getAsConstantArrayType(T: TVR->getValueType()))
55 return SVB.makeIntVal(integer: CAT->getSize(), /* isUnsigned = */ false);
56
57 return UnknownVal();
58}
59
60static DefinedOrUnknownSVal
61getDynamicElementCount(ProgramStateRef State, SVal Size,
62 DefinedOrUnknownSVal ElementSize) {
63 SValBuilder &SVB = State->getStateManager().getSValBuilder();
64
65 auto ElementCount =
66 SVB.evalBinOp(state: State, op: BO_Div, lhs: Size, rhs: ElementSize, type: SVB.getArrayIndexType())
67 .getAs<DefinedOrUnknownSVal>();
68 return ElementCount.value_or(u: UnknownVal());
69}
70
71DefinedOrUnknownSVal getDynamicElementCount(ProgramStateRef State,
72 const MemRegion *MR,
73 SValBuilder &SVB,
74 QualType ElementTy) {
75 assert(MR != nullptr && "Not-null region expected");
76 MR = MR->StripCasts();
77
78 DefinedOrUnknownSVal ElementSize = getElementExtent(Ty: ElementTy, SVB);
79 if (ElementSize.isZeroConstant())
80 return getConstantArrayElementCount(SVB, MR);
81
82 return getDynamicElementCount(State, Size: getDynamicExtent(State, MR, SVB),
83 ElementSize);
84}
85
86SVal getDynamicExtentWithOffset(ProgramStateRef State, SVal BufV) {
87 SValBuilder &SVB = State->getStateManager().getSValBuilder();
88 const MemRegion *MRegion = BufV.getAsRegion();
89 if (!MRegion)
90 return UnknownVal();
91 RegionOffset Offset = MRegion->getAsOffset();
92 if (Offset.hasSymbolicOffset())
93 return UnknownVal();
94 const MemRegion *BaseRegion = MRegion->getBaseRegion();
95 if (!BaseRegion)
96 return UnknownVal();
97
98 NonLoc OffsetInChars =
99 SVB.makeArrayIndex(idx: Offset.getOffset() / SVB.getContext().getCharWidth());
100 DefinedOrUnknownSVal ExtentInBytes = getDynamicExtent(State, MR: BaseRegion, SVB);
101
102 return SVB.evalBinOp(state: State, op: BinaryOperator::Opcode::BO_Sub, lhs: ExtentInBytes,
103 rhs: OffsetInChars, type: SVB.getArrayIndexType());
104}
105
106DefinedOrUnknownSVal getDynamicElementCountWithOffset(ProgramStateRef State,
107 SVal BufV,
108 QualType ElementTy) {
109 const MemRegion *MR = BufV.getAsRegion();
110 if (!MR)
111 return UnknownVal();
112
113 SValBuilder &SVB = State->getStateManager().getSValBuilder();
114 DefinedOrUnknownSVal ElementSize = getElementExtent(Ty: ElementTy, SVB);
115 if (ElementSize.isZeroConstant())
116 return getConstantArrayElementCount(SVB, MR);
117
118 return getDynamicElementCount(State, Size: getDynamicExtentWithOffset(State, BufV),
119 ElementSize);
120}
121
122ProgramStateRef setDynamicExtent(ProgramStateRef State, const MemRegion *MR,
123 DefinedOrUnknownSVal Size, SValBuilder &SVB) {
124 MR = MR->StripCasts();
125
126 if (Size.isUnknown())
127 return State;
128
129 return State->set<DynamicExtentMap>(K: MR->StripCasts(), E: Size);
130}
131
132} // namespace ento
133} // namespace clang
134