//===- llvm/ADT/SmallPtrSet.cpp - 'Normally small' pointer set ------------===// // // The LLVM Compiler Infrastructure // // This file 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; void SmallPtrSetImpl::shrink_and_clear() { assert(!isSmall() && "Can't shrink a small set!"); free(CurArray); // Reduce the number of buckets. CurArraySize = NumElements > 16 ? 1 << (Log2_32_Ceil(NumElements) + 1) : 32; NumElements = NumTombstones = 0; // Install the new array. Clear all the buckets to empty. CurArray = (const void**)malloc(sizeof(void*) * (CurArraySize+1)); assert(CurArray && "Failed to allocate memory?"); memset(CurArray, -1, CurArraySize*sizeof(void*)); // The end pointer, always valid, is set to a valid element to help the // iterator. CurArray[CurArraySize] = 0; } bool SmallPtrSetImpl::insert_imp(const void * Ptr) { if (isSmall()) { // Check to see if it is already in the set. for (const 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. const void **Bucket = const_cast<const 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_imp(const void * Ptr) { if (isSmall()) { // Check to see if it is in the set. for (const 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; } const void * const *SmallPtrSetImpl::FindBucketFor(const void *Ptr) const { unsigned Bucket = Hash(Ptr); unsigned ArraySize = CurArraySize; unsigned ProbeAmt = 1; const void *const *Array = CurArray; const 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; const void **OldBuckets = CurArray; bool WasSmall = isSmall(); // Install the new array. Clear all the buckets to empty. CurArray = (const 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 (const void **BucketPtr = OldBuckets, **E = OldBuckets+NumElements; BucketPtr != E; ++BucketPtr) { const void *Elt = *BucketPtr; *const_cast<void**>(FindBucketFor(Elt)) = const_cast<void*>(Elt); } } else { // Copy over all valid entries. for (const void **BucketPtr = OldBuckets, **E = OldBuckets+OldSize; BucketPtr != E; ++BucketPtr) { // Copy over the element if it is valid. const void *Elt = *BucketPtr; if (Elt != getTombstoneMarker() && Elt != getEmptyMarker()) *const_cast<void**>(FindBucketFor(Elt)) = const_cast<void*>(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 = (const 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 = (const void**)malloc(sizeof(void*) * (RHS.CurArraySize+1)); else CurArray = (const 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); }