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/StaticAnalyzer/Core/PathSensitive/MemRegion.h"
16#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
17#include "clang/StaticAnalyzer/Core/PathSensitive/SValBuilder.h"
18#include "clang/StaticAnalyzer/Core/PathSensitive/SVals.h"
19#include "clang/StaticAnalyzer/Core/PathSensitive/SymbolManager.h"
20
21REGISTER_MAP_WITH_PROGRAMSTATE(DynamicExtentMap, const clang::ento::MemRegion *,
22 clang::ento::DefinedOrUnknownSVal)
23
24namespace clang {
25namespace ento {
26
27DefinedOrUnknownSVal getDynamicExtent(ProgramStateRef State,
28 const MemRegion *MR, SValBuilder &SVB) {
29 MR = MR->StripCasts();
30
31 if (const DefinedOrUnknownSVal *Size = State->get<DynamicExtentMap>(key: MR))
32 if (auto SSize =
33 SVB.convertToArrayIndex(val: *Size).getAs<DefinedOrUnknownSVal>())
34 return *SSize;
35
36 return MR->getMemRegionManager().getStaticSize(MR, SVB);
37}
38
39DefinedOrUnknownSVal getElementExtent(QualType Ty, SValBuilder &SVB) {
40 return SVB.makeIntVal(integer: SVB.getContext().getTypeSizeInChars(T: Ty).getQuantity(),
41 type: SVB.getArrayIndexType());
42}
43
44static DefinedOrUnknownSVal getConstantArrayElementCount(SValBuilder &SVB,
45 const MemRegion *MR) {
46 MR = MR->StripCasts();
47
48 const auto *TVR = MR->getAs<TypedValueRegion>();
49 if (!TVR)
50 return UnknownVal();
51
52 if (const ConstantArrayType *CAT =
53 SVB.getContext().getAsConstantArrayType(T: TVR->getValueType()))
54 return SVB.makeIntVal(integer: CAT->getSize(), /* isUnsigned = */ false);
55
56 return UnknownVal();
57}
58
59static DefinedOrUnknownSVal
60getDynamicElementCount(ProgramStateRef State, SVal Size,
61 DefinedOrUnknownSVal ElementSize) {
62 SValBuilder &SVB = State->getStateManager().getSValBuilder();
63
64 auto ElementCount =
65 SVB.evalBinOp(state: State, op: BO_Div, lhs: Size, rhs: ElementSize, type: SVB.getArrayIndexType())
66 .getAs<DefinedOrUnknownSVal>();
67 return ElementCount.value_or(u: UnknownVal());
68}
69
70DefinedOrUnknownSVal getDynamicElementCount(ProgramStateRef State,
71 const MemRegion *MR,
72 SValBuilder &SVB,
73 QualType ElementTy) {
74 assert(MR != nullptr && "Not-null region expected");
75 MR = MR->StripCasts();
76
77 DefinedOrUnknownSVal ElementSize = getElementExtent(Ty: ElementTy, SVB);
78 if (ElementSize.isZeroConstant())
79 return getConstantArrayElementCount(SVB, MR);
80
81 return getDynamicElementCount(State, Size: getDynamicExtent(State, MR, SVB),
82 ElementSize);
83}
84
85SVal getDynamicExtentWithOffset(ProgramStateRef State, SVal BufV) {
86 SValBuilder &SVB = State->getStateManager().getSValBuilder();
87 const MemRegion *MRegion = BufV.getAsRegion();
88 if (!MRegion)
89 return UnknownVal();
90 RegionOffset Offset = MRegion->getAsOffset();
91 if (Offset.hasSymbolicOffset())
92 return UnknownVal();
93 const MemRegion *BaseRegion = MRegion->getBaseRegion();
94 if (!BaseRegion)
95 return UnknownVal();
96
97 NonLoc OffsetInChars =
98 SVB.makeArrayIndex(idx: Offset.getOffset() / SVB.getContext().getCharWidth());
99 DefinedOrUnknownSVal ExtentInBytes = getDynamicExtent(State, MR: BaseRegion, SVB);
100
101 return SVB.evalBinOp(state: State, op: BinaryOperator::Opcode::BO_Sub, lhs: ExtentInBytes,
102 rhs: OffsetInChars, type: SVB.getArrayIndexType());
103}
104
105DefinedOrUnknownSVal getDynamicElementCountWithOffset(ProgramStateRef State,
106 SVal BufV,
107 QualType ElementTy) {
108 const MemRegion *MR = BufV.getAsRegion();
109 if (!MR)
110 return UnknownVal();
111
112 SValBuilder &SVB = State->getStateManager().getSValBuilder();
113 DefinedOrUnknownSVal ElementSize = getElementExtent(Ty: ElementTy, SVB);
114 if (ElementSize.isZeroConstant())
115 return getConstantArrayElementCount(SVB, MR);
116
117 return getDynamicElementCount(State, Size: getDynamicExtentWithOffset(State, BufV),
118 ElementSize);
119}
120
121ProgramStateRef setDynamicExtent(ProgramStateRef State, const MemRegion *MR,
122 DefinedOrUnknownSVal Size) {
123 MR = MR->StripCasts();
124
125 if (Size.isUnknown())
126 return State;
127
128 return State->set<DynamicExtentMap>(K: MR->StripCasts(), E: Size);
129}
130
131} // namespace ento
132} // namespace clang
133