1 //===- llvm/ADT/SmallPtrSet.cpp - 'Normally small' pointer set ------------===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by Chris Lattner and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the SmallPtrSet class. See SmallPtrSet.h for an
11 // overview of the algorithm.
13 //===----------------------------------------------------------------------===//
15 #include "llvm/ADT/SmallPtrSet.h"
18 bool SmallPtrSetImpl::insert(void *Ptr) {
20 // Check to see if it is already in the set.
21 for (void **APtr = SmallArray, **E = SmallArray+NumElements;
26 // Nope, there isn't. If we stay small, just 'pushback' now.
27 if (NumElements < CurArraySize-1) {
28 SmallArray[NumElements++] = Ptr;
31 // Otherwise, hit the big set case, which will call grow.
34 // If more than 3/4 of the array is full, grow.
35 if (NumElements*4 >= CurArraySize*3 ||
36 CurArraySize-(NumElements+NumTombstones) < CurArraySize/8)
39 // Okay, we know we have space. Find a hash bucket.
40 void **Bucket = const_cast<void**>(FindBucketFor(Ptr));
41 if (*Bucket == Ptr) return false; // Already inserted, good.
43 // Otherwise, insert it!
44 if (*Bucket == getTombstoneMarker())
47 ++NumElements; // Track density.
51 bool SmallPtrSetImpl::erase(void *Ptr) {
53 // Check to see if it is in the set.
54 for (void **APtr = SmallArray, **E = SmallArray+NumElements;
57 // If it is in the set, replace this element.
59 E[-1] = getEmptyMarker();
67 // Okay, we know we have space. Find a hash bucket.
68 void **Bucket = const_cast<void**>(FindBucketFor(Ptr));
69 if (*Bucket != Ptr) return false; // Not in the set?
71 // Set this as a tombstone.
72 *Bucket = getTombstoneMarker();
78 void * const *SmallPtrSetImpl::FindBucketFor(void *Ptr) const {
79 unsigned Bucket = Hash(Ptr);
80 unsigned ArraySize = CurArraySize;
81 unsigned ProbeAmt = 1;
82 void *const *Array = CurArray;
83 void *const *Tombstone = 0;
85 // Found Ptr's bucket?
86 if (Array[Bucket] == Ptr)
89 // If we found an empty bucket, the pointer doesn't exist in the set.
90 // Return a tombstone if we've seen one so far, or the empty bucket if
92 if (Array[Bucket] == getEmptyMarker())
93 return Tombstone ? Tombstone : Array+Bucket;
95 // If this is a tombstone, remember it. If Ptr ends up not in the set, we
96 // prefer to return it than something that would require more probing.
97 if (Array[Bucket] == getTombstoneMarker() && !Tombstone)
98 Tombstone = Array+Bucket; // Remember the first tombstone found.
100 // It's a hash collision or a tombstone. Reprobe.
101 Bucket = (Bucket + ProbeAmt++) & (ArraySize-1);
105 /// Grow - Allocate a larger backing store for the buckets and move it over.
107 void SmallPtrSetImpl::Grow() {
108 // Allocate at twice as many buckets, but at least 128.
109 unsigned OldSize = CurArraySize;
110 unsigned NewSize = OldSize < 64 ? 128 : OldSize*2;
112 void **OldBuckets = CurArray;
113 bool WasSmall = isSmall();
115 // Install the new array. Clear all the buckets to empty.
116 CurArray = new void*[NewSize+1];
117 CurArraySize = NewSize;
118 memset(CurArray, -1, NewSize*sizeof(void*));
120 // The end pointer, always valid, is set to a valid element to help the
122 CurArray[NewSize] = 0;
124 // Copy over all the elements.
126 // Small sets store their elements in order.
127 for (void **BucketPtr = OldBuckets, **E = OldBuckets+NumElements;
128 BucketPtr != E; ++BucketPtr) {
129 void *Elt = *BucketPtr;
130 *const_cast<void**>(FindBucketFor(Elt)) = Elt;
133 // Copy over all valid entries.
134 for (void **BucketPtr = OldBuckets, **E = OldBuckets+OldSize;
135 BucketPtr != E; ++BucketPtr) {
136 // Copy over the element if it is valid.
137 void *Elt = *BucketPtr;
138 if (Elt != getTombstoneMarker() && Elt != getEmptyMarker())
139 *const_cast<void**>(FindBucketFor(Elt)) = Elt;
142 delete [] OldBuckets;
147 SmallPtrSetImpl::SmallPtrSetImpl(const SmallPtrSetImpl& that) {
148 NumElements = that.NumElements;
150 if (that.isSmall()) {
151 CurArraySize = that.CurArraySize;
152 CurArray = &SmallArray[0];
153 // Copy the entire contents of the array, including the -1's and the null
155 memcpy(CurArray, that.CurArray, sizeof(void*)*(CurArraySize+1));
157 CurArraySize = that.NumElements < 64 ? 128 : that.CurArraySize*2;
158 CurArray = new void*[CurArraySize+1];
159 memset(CurArray, -1, CurArraySize*sizeof(void*));
161 // The end pointer, always valid, is set to a valid element to help the
163 CurArray[CurArraySize] = 0;
165 // Copy over all valid entries.
166 for (void **BucketPtr = that.CurArray, **E = that.CurArray+CurArraySize;
167 BucketPtr != E; ++BucketPtr) {
168 // Copy over the element if it is valid.
169 void *Elt = *BucketPtr;
170 if (Elt != getTombstoneMarker() && Elt != getEmptyMarker())
171 *const_cast<void**>(FindBucketFor(Elt)) = Elt;