1 //===- ThreadSafetyUtil.h ---------------------------------------*- 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 some basic utility classes for use by ThreadSafetyTIL.h
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #ifndef LLVM_CLANG_ANALYSIS_ANALYSES_THREADSAFETYUTIL_H
14 #define LLVM_CLANG_ANALYSIS_ANALYSES_THREADSAFETYUTIL_H
15 
16 #include "clang/AST/Decl.h"
17 #include "clang/Basic/LLVM.h"
18 #include "llvm/ADT/StringRef.h"
19 #include "llvm/ADT/iterator_range.h"
20 #include "llvm/Support/Allocator.h"
21 #include <cassert>
22 #include <cstddef>
23 #include <cstring>
24 #include <iterator>
25 #include <ostream>
26 #include <string>
27 #include <vector>
28 
29 namespace clang {
30 
31 class Expr;
32 
33 namespace threadSafety {
34 namespace til {
35 
36 // Simple wrapper class to abstract away from the details of memory management.
37 // SExprs are allocated in pools, and deallocated all at once.
38 class MemRegionRef {
39 private:
40   union AlignmentType {
41     double d;
42     void *p;
43     long double dd;
44     long long ii;
45   };
46 
47 public:
48   MemRegionRef() = default;
49   MemRegionRef(llvm::BumpPtrAllocator *A) : Allocator(A) {}
50 
51   void *allocate(size_t Sz) {
52     return Allocator->Allocate(Sz, alignof(AlignmentType));
53   }
54 
55   template <typename T> T *allocateT() { return Allocator->Allocate<T>(); }
56 
57   template <typename T> T *allocateT(size_t NumElems) {
58     return Allocator->Allocate<T>(NumElems);
59   }
60 
61 private:
62   llvm::BumpPtrAllocator *Allocator = nullptr;
63 };
64 
65 } // namespace til
66 } // namespace threadSafety
67 
68 } // namespace clang
69 
70 inline void *operator new(size_t Sz,
71                           clang::threadSafety::til::MemRegionRef &R) {
72   return R.allocate(Sz);
73 }
74 
75 namespace clang {
76 namespace threadSafety {
77 
78 std::string getSourceLiteralString(const Expr *CE);
79 
80 namespace til {
81 
82 // A simple fixed size array class that does not manage its own memory,
83 // suitable for use with bump pointer allocation.
84 template <class T> class SimpleArray {
85 public:
86   SimpleArray() = default;
87   SimpleArray(T *Dat, size_t Cp, size_t Sz = 0)
88       : Data(Dat), Size(Sz), Capacity(Cp) {}
89   SimpleArray(MemRegionRef A, size_t Cp)
90       : Data(Cp == 0 ? nullptr : A.allocateT<T>(Cp)), Capacity(Cp) {}
91   SimpleArray(const SimpleArray<T> &A) = delete;
92 
93   SimpleArray(SimpleArray<T> &&A)
94       : Data(A.Data), Size(A.Size), Capacity(A.Capacity) {
95     A.Data = nullptr;
96     A.Size = 0;
97     A.Capacity = 0;
98   }
99 
100   SimpleArray &operator=(SimpleArray &&RHS) {
101     if (this != &RHS) {
102       Data = RHS.Data;
103       Size = RHS.Size;
104       Capacity = RHS.Capacity;
105 
106       RHS.Data = nullptr;
107       RHS.Size = RHS.Capacity = 0;
108     }
109     return *this;
110   }
111 
112   // Reserve space for at least Ncp items, reallocating if necessary.
113   void reserve(size_t Ncp, MemRegionRef A) {
114     if (Ncp <= Capacity)
115       return;
116     T *Odata = Data;
117     Data = A.allocateT<T>(Ncp);
118     Capacity = Ncp;
119     memcpy(Data, Odata, sizeof(T) * Size);
120   }
121 
122   // Reserve space for at least N more items.
123   void reserveCheck(size_t N, MemRegionRef A) {
124     if (Capacity == 0)
125       reserve(u_max(InitialCapacity, N), A);
126     else if (Size + N < Capacity)
127       reserve(u_max(Size + N, Capacity * 2), A);
128   }
129 
130   using iterator = T *;
131   using const_iterator = const T *;
132   using reverse_iterator = std::reverse_iterator<iterator>;
133   using const_reverse_iterator = std::reverse_iterator<const_iterator>;
134 
135   size_t size() const { return Size; }
136   size_t capacity() const { return Capacity; }
137 
138   T &operator[](unsigned i) {
139     assert(i < Size && "Array index out of bounds.");
140     return Data[i];
141   }
142 
143   const T &operator[](unsigned i) const {
144     assert(i < Size && "Array index out of bounds.");
145     return Data[i];
146   }
147 
148   T &back() {
149     assert(Size && "No elements in the array.");
150     return Data[Size - 1];
151   }
152 
153   const T &back() const {
154     assert(Size && "No elements in the array.");
155     return Data[Size - 1];
156   }
157 
158   iterator begin() { return Data; }
159   iterator end() { return Data + Size; }
160 
161   const_iterator begin() const { return Data; }
162   const_iterator end() const { return Data + Size; }
163 
164   const_iterator cbegin() const { return Data; }
165   const_iterator cend() const { return Data + Size; }
166 
167   reverse_iterator rbegin() { return reverse_iterator(end()); }
168   reverse_iterator rend() { return reverse_iterator(begin()); }
169 
170   const_reverse_iterator rbegin() const {
171     return const_reverse_iterator(end());
172   }
173 
174   const_reverse_iterator rend() const {
175     return const_reverse_iterator(begin());
176   }
177 
178   void push_back(const T &Elem) {
179     assert(Size < Capacity);
180     Data[Size++] = Elem;
181   }
182 
183   // drop last n elements from array
184   void drop(unsigned n = 0) {
185     assert(Size > n);
186     Size -= n;
187   }
188 
189   void setValues(unsigned Sz, const T& C) {
190     assert(Sz <= Capacity);
191     Size = Sz;
192     for (unsigned i = 0; i < Sz; ++i) {
193       Data[i] = C;
194     }
195   }
196 
197   template <class Iter> unsigned append(Iter I, Iter E) {
198     size_t Osz = Size;
199     size_t J = Osz;
200     for (; J < Capacity && I != E; ++J, ++I)
201       Data[J] = *I;
202     Size = J;
203     return J - Osz;
204   }
205 
206   llvm::iterator_range<reverse_iterator> reverse() {
207     return llvm::make_range(rbegin(), rend());
208   }
209 
210   llvm::iterator_range<const_reverse_iterator> reverse() const {
211     return llvm::make_range(rbegin(), rend());
212   }
213 
214 private:
215   // std::max is annoying here, because it requires a reference,
216   // thus forcing InitialCapacity to be initialized outside the .h file.
217   size_t u_max(size_t i, size_t j) { return (i < j) ? j : i; }
218 
219   static const size_t InitialCapacity = 4;
220 
221   T *Data = nullptr;
222   size_t Size = 0;
223   size_t Capacity = 0;
224 };
225 
226 }  // namespace til
227 
228 // A copy on write vector.
229 // The vector can be in one of three states:
230 // * invalid -- no operations are permitted.
231 // * read-only -- read operations are permitted.
232 // * writable -- read and write operations are permitted.
233 // The init(), destroy(), and makeWritable() methods will change state.
234 template<typename T>
235 class CopyOnWriteVector {
236   class VectorData {
237   public:
238     unsigned NumRefs = 1;
239     std::vector<T> Vect;
240 
241     VectorData() = default;
242     VectorData(const VectorData &VD) : Vect(VD.Vect) {}
243   };
244 
245 public:
246   CopyOnWriteVector() = default;
247   CopyOnWriteVector(CopyOnWriteVector &&V) : Data(V.Data) { V.Data = nullptr; }
248 
249   CopyOnWriteVector &operator=(CopyOnWriteVector &&V) {
250     destroy();
251     Data = V.Data;
252     V.Data = nullptr;
253     return *this;
254   }
255 
256   // No copy constructor or copy assignment.  Use clone() with move assignment.
257   CopyOnWriteVector(const CopyOnWriteVector &) = delete;
258   CopyOnWriteVector &operator=(const CopyOnWriteVector &) = delete;
259 
260   ~CopyOnWriteVector() { destroy(); }
261 
262   // Returns true if this holds a valid vector.
263   bool valid() const  { return Data; }
264 
265   // Returns true if this vector is writable.
266   bool writable() const { return Data && Data->NumRefs == 1; }
267 
268   // If this vector is not valid, initialize it to a valid vector.
269   void init() {
270     if (!Data) {
271       Data = new VectorData();
272     }
273   }
274 
275   // Destroy this vector; thus making it invalid.
276   void destroy() {
277     if (!Data)
278       return;
279     if (Data->NumRefs <= 1)
280       delete Data;
281     else
282       --Data->NumRefs;
283     Data = nullptr;
284   }
285 
286   // Make this vector writable, creating a copy if needed.
287   void makeWritable() {
288     if (!Data) {
289       Data = new VectorData();
290       return;
291     }
292     if (Data->NumRefs == 1)
293       return;   // already writeable.
294     --Data->NumRefs;
295     Data = new VectorData(*Data);
296   }
297 
298   // Create a lazy copy of this vector.
299   CopyOnWriteVector clone() { return CopyOnWriteVector(Data); }
300 
301   using const_iterator = typename std::vector<T>::const_iterator;
302 
303   const std::vector<T> &elements() const { return Data->Vect; }
304 
305   const_iterator begin() const { return elements().cbegin(); }
306   const_iterator end() const { return elements().cend(); }
307 
308   const T& operator[](unsigned i) const { return elements()[i]; }
309 
310   unsigned size() const { return Data ? elements().size() : 0; }
311 
312   // Return true if V and this vector refer to the same data.
313   bool sameAs(const CopyOnWriteVector &V) const { return Data == V.Data; }
314 
315   // Clear vector.  The vector must be writable.
316   void clear() {
317     assert(writable() && "Vector is not writable!");
318     Data->Vect.clear();
319   }
320 
321   // Push a new element onto the end.  The vector must be writable.
322   void push_back(const T &Elem) {
323     assert(writable() && "Vector is not writable!");
324     Data->Vect.push_back(Elem);
325   }
326 
327   // Gets a mutable reference to the element at index(i).
328   // The vector must be writable.
329   T& elem(unsigned i) {
330     assert(writable() && "Vector is not writable!");
331     return Data->Vect[i];
332   }
333 
334   // Drops elements from the back until the vector has size i.
335   void downsize(unsigned i) {
336     assert(writable() && "Vector is not writable!");
337     Data->Vect.erase(Data->Vect.begin() + i, Data->Vect.end());
338   }
339 
340 private:
341   CopyOnWriteVector(VectorData *D) : Data(D) {
342     if (!Data)
343       return;
344     ++Data->NumRefs;
345   }
346 
347   VectorData *Data = nullptr;
348 };
349 
350 inline std::ostream& operator<<(std::ostream& ss, const StringRef str) {
351   return ss.write(str.data(), str.size());
352 }
353 
354 } // namespace threadSafety
355 } // namespace clang
356 
357 #endif // LLVM_CLANG_ANALYSIS_ANALYSES_THREADSAFETYUTIL_H
358