clang  10.0.0svn
Pointer.cpp
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1 //===--- Pointer.cpp - Types for the constexpr VM ---------------*- 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 "Pointer.h"
10 #include "Block.h"
11 #include "Function.h"
12 #include "PrimType.h"
13 
14 using namespace clang;
15 using namespace clang::interp;
16 
17 Pointer::Pointer(Block *Pointee) : Pointer(Pointee, 0, 0) {}
18 
19 Pointer::Pointer(const Pointer &P) : Pointer(P.Pointee, P.Base, P.Offset) {}
20 
22  : Pointee(P.Pointee), Base(P.Base), Offset(P.Offset) {
23  if (Pointee)
24  Pointee->movePointer(&P, this);
25 }
26 
27 Pointer::Pointer(Block *Pointee, unsigned Base, unsigned Offset)
28  : Pointee(Pointee), Base(Base), Offset(Offset) {
29  assert((Base == RootPtrMark || Base % alignof(void *) == 0) && "wrong base");
30  if (Pointee)
31  Pointee->addPointer(this);
32 }
33 
35  if (Pointee) {
36  Pointee->removePointer(this);
37  Pointee->cleanup();
38  }
39 }
40 
42  Block *Old = Pointee;
43 
44  if (Pointee)
45  Pointee->removePointer(this);
46 
47  Offset = P.Offset;
48  Base = P.Base;
49 
50  Pointee = P.Pointee;
51  if (Pointee)
52  Pointee->addPointer(this);
53 
54  if (Old)
55  Old->cleanup();
56 }
57 
59  Block *Old = Pointee;
60 
61  if (Pointee)
62  Pointee->removePointer(this);
63 
64  Offset = P.Offset;
65  Base = P.Base;
66 
67  Pointee = P.Pointee;
68  if (Pointee)
69  Pointee->movePointer(&P, this);
70 
71  if (Old)
72  Old->cleanup();
73 }
74 
78  CharUnits Offset;
79  bool IsNullPtr;
80  bool IsOnePastEnd;
81 
82  if (isZero()) {
83  Base = static_cast<const Expr *>(nullptr);
84  IsNullPtr = true;
85  IsOnePastEnd = false;
86  Offset = CharUnits::Zero();
87  } else {
88  // Build the lvalue base from the block.
89  Descriptor *Desc = getDeclDesc();
90  if (auto *VD = Desc->asValueDecl())
91  Base = VD;
92  else if (auto *E = Desc->asExpr())
93  Base = E;
94  else
95  llvm_unreachable("Invalid allocation type");
96 
97  // Not a null pointer.
98  IsNullPtr = false;
99 
100  if (isUnknownSizeArray()) {
101  IsOnePastEnd = false;
102  Offset = CharUnits::Zero();
103  } else {
104  // TODO: compute the offset into the object.
105  Offset = CharUnits::Zero();
106 
107  // Build the path into the object.
108  Pointer Ptr = *this;
109  while (Ptr.isField()) {
110  if (Ptr.isArrayElement()) {
111  Path.push_back(APValue::LValuePathEntry::ArrayIndex(Ptr.getIndex()));
112  Ptr = Ptr.getArray();
113  } else {
114  // TODO: figure out if base is virtual
115  bool IsVirtual = false;
116 
117  // Create a path entry for the field.
118  Descriptor *Desc = Ptr.getFieldDesc();
119  if (auto *BaseOrMember = Desc->asDecl()) {
120  Path.push_back(APValue::LValuePathEntry({BaseOrMember, IsVirtual}));
121  Ptr = Ptr.getBase();
122  continue;
123  }
124  llvm_unreachable("Invalid field type");
125  }
126  }
127 
128  IsOnePastEnd = isOnePastEnd();
129  }
130  }
131 
132  return APValue(Base, Offset, Path, IsOnePastEnd, IsNullPtr);
133 }
134 
136  assert(Pointee && "Cannot check if null pointer was initialized");
137  Descriptor *Desc = getFieldDesc();
138  if (Desc->isPrimitiveArray()) {
139  if (Pointee->IsStatic)
140  return true;
141  // Primitive array field are stored in a bitset.
142  InitMap *Map = getInitMap();
143  if (!Map)
144  return false;
145  if (Map == (InitMap *)-1)
146  return true;
147  return Map->isInitialized(getIndex());
148  } else {
149  // Field has its bit in an inline descriptor.
150  return Base == 0 || getInlineDesc()->IsInitialized;
151  }
152 }
153 
154 void Pointer::initialize() const {
155  assert(Pointee && "Cannot initialize null pointer");
156  Descriptor *Desc = getFieldDesc();
157  if (Desc->isPrimitiveArray()) {
158  if (!Pointee->IsStatic) {
159  // Primitive array initializer.
160  InitMap *&Map = getInitMap();
161  if (Map == (InitMap *)-1)
162  return;
163  if (Map == nullptr)
164  Map = InitMap::allocate(Desc->getNumElems());
165  if (Map->initialize(getIndex())) {
166  free(Map);
167  Map = (InitMap *)-1;
168  }
169  }
170  } else {
171  // Field has its bit in an inline descriptor.
172  assert(Base != 0 && "Only composite fields can be initialised");
173  getInlineDesc()->IsInitialized = true;
174  }
175 }
176 
177 void Pointer::activate() const {
178  // Field has its bit in an inline descriptor.
179  assert(Base != 0 && "Only composite fields can be initialised");
180  getInlineDesc()->IsActive = true;
181 }
182 
183 void Pointer::deactivate() const {
184  // TODO: this only appears in constructors, so nothing to deactivate.
185 }
186 
187 bool Pointer::hasSameBase(const Pointer &A, const Pointer &B) {
188  return A.Pointee == B.Pointee;
189 }
190 
191 bool Pointer::hasSameArray(const Pointer &A, const Pointer &B) {
192  return A.Base == B.Base && A.getFieldDesc()->IsArray;
193 }
static LValuePathEntry ArrayIndex(uint64_t Index)
Definition: APValue.h:204
void initialize() const
Initializes a field.
Definition: Pointer.cpp:154
unsigned IsActive
Flag indicating if the field is the active member of a union.
Definition: Descriptor.h:178
bool isPrimitiveArray() const
Checks if the descriptor is of an array of primitives.
Definition: Descriptor.h:144
StringRef P
void activate() const
Activats a field.
Definition: Pointer.cpp:177
A pointer to a memory block, live or dead.
Definition: Pointer.h:39
Bitfield tracking the initialisation status of elements of primitive arrays.
Definition: Descriptor.h:189
unsigned IsInitialized
For primitive fields, it indicates if the field was initialized.
Definition: Descriptor.h:174
A memory block, either on the stack or in the heap.
Definition: Block.h:37
void movePointer(Pointer *From, Pointer *To)
Definition: Block.cpp:47
static CharUnits Zero()
Zero - Construct a CharUnits quantity of zero.
Definition: CharUnits.h:53
const Decl * asDecl() const
Definition: Descriptor.h:112
CharUnits - This is an opaque type for sizes expressed in character units.
Definition: CharUnits.h:38
bool isInitialized(unsigned I)
Checks if an element was initialized.
Definition: Descriptor.cpp:282
const ValueDecl * asValueDecl() const
Definition: Descriptor.h:115
void operator=(const Pointer &P)
Definition: Pointer.cpp:41
static bool hasSameBase(const Pointer &A, const Pointer &B)
Checks if two pointers are comparable.
Definition: Pointer.cpp:187
Describes a memory block created by an allocation site.
Definition: Descriptor.h:51
void removePointer(Pointer *P)
Definition: Block.cpp:31
This represents one expression.
Definition: Expr.h:108
A non-discriminated union of a base, field, or array index.
Definition: APValue.h:195
bool isField() const
Checks if the item is a field in an object.
Definition: Pointer.h:144
void deactivate() const
Deactivates an entire strurcutre.
Definition: Pointer.cpp:183
bool isArrayElement() const
Checks if the pointer points to an array.
Definition: Pointer.h:214
const bool IsArray
Flag indicating if the block is an array.
Definition: Descriptor.h:80
Descriptor * getFieldDesc() const
Accessors for information about the innermost field.
Definition: Pointer.h:171
bool IsStatic
Flag indicating if the block has static storage duration.
Definition: Block.h:99
const Expr * asExpr() const
Definition: Descriptor.h:113
static bool hasSameArray(const Pointer &A, const Pointer &B)
Checks if two pointers can be subtracted.
Definition: Pointer.cpp:191
bool initialize(unsigned I)
Initializes an element. Returns true when object if fully initialized.
Definition: Descriptor.cpp:272
static InitMap * allocate(unsigned N)
Allocates a map holding N elements.
Definition: Descriptor.cpp:288
Dataflow Directional Tag Classes.
Pointer getArray() const
Returns the parent array.
Definition: Pointer.h:161
bool isInitialized() const
Checks if an object was initialized.
Definition: Pointer.cpp:135
bool isUnknownSizeArray() const
Checks if the structure is an array of unknown size.
Definition: Pointer.h:210
int64_t getIndex() const
Returns the index into an array.
Definition: Pointer.h:263
bool isOnePastEnd() const
Checks if the index is one past end.
Definition: Pointer.h:272
bool isZero() const
Checks if the pointer is null.
Definition: Pointer.h:140
Descriptor * getDeclDesc() const
Accessor for information about the declaration site.
Definition: Pointer.h:147
APValue - This class implements a discriminated union of [uninitialized] [APSInt] [APFloat]...
Definition: APValue.h:115
unsigned getNumElems() const
Returns the number of elements stored in the block.
Definition: Descriptor.h:139
void addPointer(Pointer *P)
Definition: Block.cpp:21
APValue toAPValue() const
Converts the pointer to an APValue.
Definition: Pointer.cpp:75
Pointer getBase() const
Returns a pointer to the object of which this pointer is a field.
Definition: Pointer.h:151