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//===- llvm/ADT/SmallPtrSet.cpp - 'Normally small' pointer set ------------===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by Chris Lattner and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the SmallPtrSet class. See SmallPtrSet.h for an
// overview of the algorithm.
//
//===----------------------------------------------------------------------===//
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/Support/MathExtras.h"
#include <cstdlib>
using namespace llvm;
bool SmallPtrSetImpl::insert(void *Ptr) {
if (isSmall()) {
// Check to see if it is already in the set.
for (void **APtr = SmallArray, **E = SmallArray+NumElements;
APtr != E; ++APtr)
if (*APtr == Ptr)
return false;
// Nope, there isn't. If we stay small, just 'pushback' now.
if (NumElements < CurArraySize-1) {
SmallArray[NumElements++] = Ptr;
return true;
}
// Otherwise, hit the big set case, which will call grow.
}
// If more than 3/4 of the array is full, grow.
if (NumElements*4 >= CurArraySize*3 ||
CurArraySize-(NumElements+NumTombstones) < CurArraySize/8)
Grow();
// Okay, we know we have space. Find a hash bucket.
void **Bucket = const_cast<void**>(FindBucketFor(Ptr));
if (*Bucket == Ptr) return false; // Already inserted, good.
// Otherwise, insert it!
if (*Bucket == getTombstoneMarker())
--NumTombstones;
*Bucket = Ptr;
++NumElements; // Track density.
return true;
}
bool SmallPtrSetImpl::erase(void *Ptr) {
if (isSmall()) {
// Check to see if it is in the set.
for (void **APtr = SmallArray, **E = SmallArray+NumElements;
APtr != E; ++APtr)
if (*APtr == Ptr) {
// If it is in the set, replace this element.
*APtr = E[-1];
E[-1] = getEmptyMarker();
--NumElements;
return true;
}
return false;
}
// Okay, we know we have space. Find a hash bucket.
void **Bucket = const_cast<void**>(FindBucketFor(Ptr));
if (*Bucket != Ptr) return false; // Not in the set?
// Set this as a tombstone.
*Bucket = getTombstoneMarker();
--NumElements;
++NumTombstones;
return true;
}
void * const *SmallPtrSetImpl::FindBucketFor(void *Ptr) const {
unsigned Bucket = Hash(Ptr);
unsigned ArraySize = CurArraySize;
unsigned ProbeAmt = 1;
void *const *Array = CurArray;
void *const *Tombstone = 0;
while (1) {
// Found Ptr's bucket?
if (Array[Bucket] == Ptr)
return Array+Bucket;
// If we found an empty bucket, the pointer doesn't exist in the set.
// Return a tombstone if we've seen one so far, or the empty bucket if
// not.
if (Array[Bucket] == getEmptyMarker())
return Tombstone ? Tombstone : Array+Bucket;
// If this is a tombstone, remember it. If Ptr ends up not in the set, we
// prefer to return it than something that would require more probing.
if (Array[Bucket] == getTombstoneMarker() && !Tombstone)
Tombstone = Array+Bucket; // Remember the first tombstone found.
// It's a hash collision or a tombstone. Reprobe.
Bucket = (Bucket + ProbeAmt++) & (ArraySize-1);
}
}
/// Grow - Allocate a larger backing store for the buckets and move it over.
///
void SmallPtrSetImpl::Grow() {
// Allocate at twice as many buckets, but at least 128.
unsigned OldSize = CurArraySize;
unsigned NewSize = OldSize < 64 ? 128 : OldSize*2;
void **OldBuckets = CurArray;
bool WasSmall = isSmall();
// Install the new array. Clear all the buckets to empty.
CurArray = (void**)malloc(sizeof(void*) * (NewSize+1));
assert(CurArray && "Failed to allocate memory?");
CurArraySize = NewSize;
memset(CurArray, -1, NewSize*sizeof(void*));
// The end pointer, always valid, is set to a valid element to help the
// iterator.
CurArray[NewSize] = 0;
// Copy over all the elements.
if (WasSmall) {
// Small sets store their elements in order.
for (void **BucketPtr = OldBuckets, **E = OldBuckets+NumElements;
BucketPtr != E; ++BucketPtr) {
void *Elt = *BucketPtr;
*const_cast<void**>(FindBucketFor(Elt)) = Elt;
}
} else {
// Copy over all valid entries.
for (void **BucketPtr = OldBuckets, **E = OldBuckets+OldSize;
BucketPtr != E; ++BucketPtr) {
// Copy over the element if it is valid.
void *Elt = *BucketPtr;
if (Elt != getTombstoneMarker() && Elt != getEmptyMarker())
*const_cast<void**>(FindBucketFor(Elt)) = Elt;
}
free(OldBuckets);
NumTombstones = 0;
}
}
SmallPtrSetImpl::SmallPtrSetImpl(const SmallPtrSetImpl& that) {
// If we're becoming small, prepare to insert into our stack space
if (that.isSmall()) {
CurArray = &SmallArray[0];
// Otherwise, allocate new heap space (unless we were the same size)
} else {
CurArray = (void**)malloc(sizeof(void*) * (that.CurArraySize+1));
assert(CurArray && "Failed to allocate memory?");
}
// Copy over the new array size
CurArraySize = that.CurArraySize;
// Copy over the contents from the other set
memcpy(CurArray, that.CurArray, sizeof(void*)*(CurArraySize+1));
NumElements = that.NumElements;
NumTombstones = that.NumTombstones;
}
/// CopyFrom - implement operator= from a smallptrset that has the same pointer
/// type, but may have a different small size.
void SmallPtrSetImpl::CopyFrom(const SmallPtrSetImpl &RHS) {
if (isSmall() && RHS.isSmall())
assert(CurArraySize == RHS.CurArraySize &&
"Cannot assign sets with different small sizes");
// If we're becoming small, prepare to insert into our stack space
if (RHS.isSmall()) {
if (!isSmall())
free(CurArray);
CurArray = &SmallArray[0];
// Otherwise, allocate new heap space (unless we were the same size)
} else if (CurArraySize != RHS.CurArraySize) {
if (isSmall())
CurArray = (void**)malloc(sizeof(void*) * (RHS.CurArraySize+1));
else
CurArray = (void**)realloc(CurArray, sizeof(void*)*(RHS.CurArraySize+1));
assert(CurArray && "Failed to allocate memory?");
}
// Copy over the new array size
CurArraySize = RHS.CurArraySize;
// Copy over the contents from the other set
memcpy(CurArray, RHS.CurArray, sizeof(void*)*(CurArraySize+1));
NumElements = RHS.NumElements;
NumTombstones = RHS.NumTombstones;
}
SmallPtrSetImpl::~SmallPtrSetImpl() {
if (!isSmall())
free(CurArray);
}
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