LLVM 19.0.0git
SmallPtrSet.cpp
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1//===- llvm/ADT/SmallPtrSet.cpp - 'Normally small' pointer set ------------===//
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 implements the SmallPtrSet class. See SmallPtrSet.h for an
10// overview of the algorithm.
11//
12//===----------------------------------------------------------------------===//
13
18#include <algorithm>
19#include <cassert>
20#include <cstdlib>
21
22using namespace llvm;
23
24void SmallPtrSetImplBase::shrink_and_clear() {
25 assert(!isSmall() && "Can't shrink a small set!");
26 free(CurArray);
27
28 // Reduce the number of buckets.
29 unsigned Size = size();
30 CurArraySize = Size > 16 ? 1 << (Log2_32_Ceil(Size) + 1) : 32;
32
33 // Install the new array. Clear all the buckets to empty.
34 CurArray = (const void**)safe_malloc(sizeof(void*) * CurArraySize);
35
36 memset(CurArray, -1, CurArraySize*sizeof(void*));
37}
38
39std::pair<const void *const *, bool>
40SmallPtrSetImplBase::insert_imp_big(const void *Ptr) {
41 if (LLVM_UNLIKELY(size() * 4 >= CurArraySize * 3)) {
42 // If more than 3/4 of the array is full, grow.
43 Grow(CurArraySize < 64 ? 128 : CurArraySize * 2);
45 // If fewer of 1/8 of the array is empty (meaning that many are filled with
46 // tombstones), rehash.
47 Grow(CurArraySize);
48 }
49
50 // Okay, we know we have space. Find a hash bucket.
51 const void **Bucket = const_cast<const void**>(FindBucketFor(Ptr));
52 if (*Bucket == Ptr)
53 return std::make_pair(Bucket, false); // Already inserted, good.
54
55 // Otherwise, insert it!
56 if (*Bucket == getTombstoneMarker())
58 else
59 ++NumNonEmpty; // Track density.
60 *Bucket = Ptr;
62 return std::make_pair(Bucket, true);
63}
64
65const void * const *SmallPtrSetImplBase::FindBucketFor(const void *Ptr) const {
67 unsigned ArraySize = CurArraySize;
68 unsigned ProbeAmt = 1;
69 const void *const *Array = CurArray;
70 const void *const *Tombstone = nullptr;
71 while (true) {
72 // If we found an empty bucket, the pointer doesn't exist in the set.
73 // Return a tombstone if we've seen one so far, or the empty bucket if
74 // not.
75 if (LLVM_LIKELY(Array[Bucket] == getEmptyMarker()))
76 return Tombstone ? Tombstone : Array+Bucket;
77
78 // Found Ptr's bucket?
79 if (LLVM_LIKELY(Array[Bucket] == Ptr))
80 return Array+Bucket;
81
82 // If this is a tombstone, remember it. If Ptr ends up not in the set, we
83 // prefer to return it than something that would require more probing.
84 if (Array[Bucket] == getTombstoneMarker() && !Tombstone)
85 Tombstone = Array+Bucket; // Remember the first tombstone found.
86
87 // It's a hash collision or a tombstone. Reprobe.
88 Bucket = (Bucket + ProbeAmt++) & (ArraySize-1);
89 }
90}
91
92/// Grow - Allocate a larger backing store for the buckets and move it over.
93///
94void SmallPtrSetImplBase::Grow(unsigned NewSize) {
95 const void **OldBuckets = CurArray;
96 const void **OldEnd = EndPointer();
97 bool WasSmall = isSmall();
98
99 // Install the new array. Clear all the buckets to empty.
100 const void **NewBuckets = (const void**) safe_malloc(sizeof(void*) * NewSize);
101
102 // Reset member only if memory was allocated successfully
103 CurArray = NewBuckets;
104 CurArraySize = NewSize;
105 memset(CurArray, -1, NewSize*sizeof(void*));
106
107 // Copy over all valid entries.
108 for (const void **BucketPtr = OldBuckets; BucketPtr != OldEnd; ++BucketPtr) {
109 // Copy over the element if it is valid.
110 const void *Elt = *BucketPtr;
111 if (Elt != getTombstoneMarker() && Elt != getEmptyMarker())
112 *const_cast<void**>(FindBucketFor(Elt)) = const_cast<void*>(Elt);
113 }
114
115 if (!WasSmall)
116 free(OldBuckets);
118 NumTombstones = 0;
119}
120
122 const SmallPtrSetImplBase &that) {
123 SmallArray = SmallStorage;
124
125 // If we're becoming small, prepare to insert into our stack space
126 if (that.isSmall()) {
128 // Otherwise, allocate new heap space (unless we were the same size)
129 } else {
130 CurArray = (const void**)safe_malloc(sizeof(void*) * that.CurArraySize);
131 }
132
133 // Copy over the that array.
134 CopyHelper(that);
135}
136
138 unsigned SmallSize,
139 SmallPtrSetImplBase &&that) {
140 SmallArray = SmallStorage;
141 MoveHelper(SmallSize, std::move(that));
142}
143
145 assert(&RHS != this && "Self-copy should be handled by the caller.");
146
147 if (isSmall() && RHS.isSmall())
148 assert(CurArraySize == RHS.CurArraySize &&
149 "Cannot assign sets with different small sizes");
150
151 // If we're becoming small, prepare to insert into our stack space
152 if (RHS.isSmall()) {
153 if (!isSmall())
154 free(CurArray);
156 // Otherwise, allocate new heap space (unless we were the same size)
157 } else if (CurArraySize != RHS.CurArraySize) {
158 if (isSmall())
159 CurArray = (const void**)safe_malloc(sizeof(void*) * RHS.CurArraySize);
160 else {
161 const void **T = (const void**)safe_realloc(CurArray,
162 sizeof(void*) * RHS.CurArraySize);
163 CurArray = T;
164 }
165 }
166
167 CopyHelper(RHS);
168}
169
170void SmallPtrSetImplBase::CopyHelper(const SmallPtrSetImplBase &RHS) {
171 // Copy over the new array size
172 CurArraySize = RHS.CurArraySize;
173
174 // Copy over the contents from the other set
175 std::copy(RHS.CurArray, RHS.EndPointer(), CurArray);
176
177 NumNonEmpty = RHS.NumNonEmpty;
178 NumTombstones = RHS.NumTombstones;
179}
180
181void SmallPtrSetImplBase::MoveFrom(unsigned SmallSize,
182 SmallPtrSetImplBase &&RHS) {
183 if (!isSmall())
184 free(CurArray);
185 MoveHelper(SmallSize, std::move(RHS));
186}
187
188void SmallPtrSetImplBase::MoveHelper(unsigned SmallSize,
189 SmallPtrSetImplBase &&RHS) {
190 assert(&RHS != this && "Self-move should be handled by the caller.");
191
192 if (RHS.isSmall()) {
193 // Copy a small RHS rather than moving.
195 std::copy(RHS.CurArray, RHS.CurArray + RHS.NumNonEmpty, CurArray);
196 } else {
197 CurArray = RHS.CurArray;
198 RHS.CurArray = RHS.SmallArray;
199 }
200
201 // Copy the rest of the trivial members.
202 CurArraySize = RHS.CurArraySize;
203 NumNonEmpty = RHS.NumNonEmpty;
204 NumTombstones = RHS.NumTombstones;
205
206 // Make the RHS small and empty.
207 RHS.CurArraySize = SmallSize;
208 assert(RHS.CurArray == RHS.SmallArray);
209 RHS.NumNonEmpty = 0;
210 RHS.NumTombstones = 0;
211}
212
214 if (this == &RHS) return;
215
216 // We can only avoid copying elements if neither set is small.
217 if (!this->isSmall() && !RHS.isSmall()) {
218 std::swap(this->CurArray, RHS.CurArray);
220 std::swap(this->NumNonEmpty, RHS.NumNonEmpty);
222 return;
223 }
224
225 // FIXME: From here on we assume that both sets have the same small size.
226
227 // If only RHS is small, copy the small elements into LHS and move the pointer
228 // from LHS to RHS.
229 if (!this->isSmall() && RHS.isSmall()) {
230 assert(RHS.CurArray == RHS.SmallArray);
231 std::copy(RHS.CurArray, RHS.CurArray + RHS.NumNonEmpty, this->SmallArray);
232 std::swap(RHS.CurArraySize, this->CurArraySize);
233 std::swap(this->NumNonEmpty, RHS.NumNonEmpty);
235 RHS.CurArray = this->CurArray;
236 this->CurArray = this->SmallArray;
237 return;
238 }
239
240 // If only LHS is small, copy the small elements into RHS and move the pointer
241 // from RHS to LHS.
242 if (this->isSmall() && !RHS.isSmall()) {
243 assert(this->CurArray == this->SmallArray);
244 std::copy(this->CurArray, this->CurArray + this->NumNonEmpty,
245 RHS.SmallArray);
246 std::swap(RHS.CurArraySize, this->CurArraySize);
247 std::swap(RHS.NumNonEmpty, this->NumNonEmpty);
248 std::swap(RHS.NumTombstones, this->NumTombstones);
249 this->CurArray = RHS.CurArray;
250 RHS.CurArray = RHS.SmallArray;
251 return;
252 }
253
254 // Both a small, just swap the small elements.
255 assert(this->isSmall() && RHS.isSmall());
256 unsigned MinNonEmpty = std::min(this->NumNonEmpty, RHS.NumNonEmpty);
257 std::swap_ranges(this->SmallArray, this->SmallArray + MinNonEmpty,
258 RHS.SmallArray);
259 if (this->NumNonEmpty > MinNonEmpty) {
260 std::copy(this->SmallArray + MinNonEmpty,
261 this->SmallArray + this->NumNonEmpty,
262 RHS.SmallArray + MinNonEmpty);
263 } else {
264 std::copy(RHS.SmallArray + MinNonEmpty, RHS.SmallArray + RHS.NumNonEmpty,
265 this->SmallArray + MinNonEmpty);
266 }
267 assert(this->CurArraySize == RHS.CurArraySize);
268 std::swap(this->NumNonEmpty, RHS.NumNonEmpty);
270}
#define LLVM_UNLIKELY(EXPR)
Definition: Compiler.h:241
#define LLVM_LIKELY(EXPR)
Definition: Compiler.h:240
This file defines DenseMapInfo traits for DenseMap.
uint64_t Size
This file defines counterparts of C library allocation functions defined in the namespace 'std'.
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
This file defines the SmallPtrSet class.
Value * RHS
SmallPtrSetImplBase - This is the common code shared among all the SmallPtrSet<>'s,...
Definition: SmallPtrSet.h:51
size_type size() const
Definition: SmallPtrSet.h:94
unsigned NumTombstones
Number of tombstones in CurArray.
Definition: SmallPtrSet.h:68
void MoveFrom(unsigned SmallSize, SmallPtrSetImplBase &&RHS)
SmallPtrSetImplBase(const void **SmallStorage, const SmallPtrSetImplBase &that)
const void ** CurArray
CurArray - This is the current set of buckets.
Definition: SmallPtrSet.h:59
unsigned NumNonEmpty
Number of elements in CurArray that contain a value or are a tombstone.
Definition: SmallPtrSet.h:66
const void ** SmallArray
SmallArray - Points to a fixed size set of buckets, used in 'small mode'.
Definition: SmallPtrSet.h:56
void CopyFrom(const SmallPtrSetImplBase &RHS)
unsigned CurArraySize
CurArraySize - The allocated size of CurArray, always a power of two.
Definition: SmallPtrSet.h:61
const void ** EndPointer() const
Definition: SmallPtrSet.h:120
static void * getEmptyMarker()
Definition: SmallPtrSet.h:114
static void * getTombstoneMarker()
Definition: SmallPtrSet.h:112
void swap(SmallPtrSetImplBase &RHS)
swap - Swaps the elements of two sets.
This is an optimization pass for GlobalISel generic memory operations.
Definition: AddressRanges.h:18
unsigned Log2_32_Ceil(uint32_t Value)
Return the ceil log base 2 of the specified value, 32 if the value is zero.
Definition: MathExtras.h:326
LLVM_ATTRIBUTE_RETURNS_NONNULL void * safe_malloc(size_t Sz)
Definition: MemAlloc.h:25
LLVM_ATTRIBUTE_RETURNS_NONNULL void * safe_realloc(void *Ptr, size_t Sz)
Definition: MemAlloc.h:52
void swap(llvm::BitVector &LHS, llvm::BitVector &RHS)
Implement std::swap in terms of BitVector swap.
Definition: BitVector.h:860
An information struct used to provide DenseMap with the various necessary components for a given valu...
Definition: DenseMapInfo.h:50