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//===-- sanitizer_bitvector.h -----------------------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// Specializer BitVector implementation.
//
//===----------------------------------------------------------------------===//
#ifndef SANITIZER_BITVECTOR_H
#define SANITIZER_BITVECTOR_H
#include "sanitizer_common.h"
namespace __sanitizer {
// Fixed size bit vector based on a single basic integer.
template <class basic_int_t = uptr>
class BasicBitVector {
public:
enum SizeEnum { kSize = sizeof(basic_int_t) * 8 };
uptr size() const { return kSize; }
// No CTOR.
void clear() { bits_ = 0; }
void setAll() { bits_ = ~(basic_int_t)0; }
bool empty() const { return bits_ == 0; }
// Returns true if the bit has changed from 0 to 1.
bool setBit(uptr idx) {
basic_int_t old = bits_;
bits_ |= mask(idx);
return bits_ != old;
}
// Returns true if the bit has changed from 1 to 0.
bool clearBit(uptr idx) {
basic_int_t old = bits_;
bits_ &= ~mask(idx);
return bits_ != old;
}
bool getBit(uptr idx) const { return bits_ & mask(idx); }
uptr getAndClearFirstOne() {
CHECK(!empty());
// FIXME: change to LeastSignificantSetBitIndex?
uptr idx = MostSignificantSetBitIndex(bits_);
clearBit(idx);
return idx;
}
// Do "this |= v" and return whether new bits have been added.
bool setUnion(const BasicBitVector &v) {
basic_int_t old = bits_;
bits_ |= v.bits_;
return bits_ != old;
}
void copyFrom(const BasicBitVector &v) { bits_ = v.bits_; }
// Returns true if 'this' intersects with 'v'.
bool intersectsWith(const BasicBitVector &v) const { return bits_ & v.bits_; }
private:
basic_int_t mask(uptr idx) const {
CHECK_LT(idx, size());
return (basic_int_t)1UL << idx;
}
basic_int_t bits_;
};
// Fixed size bit vector of (kLevel1Size*BV::kSize**2) bits.
// The implementation is optimized for better performance on
// sparse bit vectors, i.e. the those with few set bits.
template <uptr kLevel1Size = 1, class BV = BasicBitVector<> >
class TwoLevelBitVector {
// This is essentially a 2-level bit vector.
// Set bit in the first level BV indicates that there are set bits
// in the corresponding BV of the second level.
// This structure allows O(kLevel1Size) time for clear() and empty(),
// as well fast handling of sparse BVs.
public:
enum SizeEnum { kSize = BV::kSize * BV::kSize * kLevel1Size };
// No CTOR.
uptr size() const { return kSize; }
void clear() {
for (uptr i = 0; i < kLevel1Size; i++)
l1_[i].clear();
}
void setAll() {
for (uptr i0 = 0; i0 < kLevel1Size; i0++) {
l1_[i0].setAll();
for (uptr i1 = 0; i1 < BV::kSize; i1++)
l2_[i0][i1].setAll();
}
}
bool empty() {
for (uptr i = 0; i < kLevel1Size; i++)
if (!l1_[i].empty())
return false;
return true;
}
// Returns true if the bit has changed from 0 to 1.
bool setBit(uptr idx) {
check(idx);
uptr i0 = idx0(idx);
uptr i1 = idx1(idx);
uptr i2 = idx2(idx);
if (!l1_[i0].getBit(i1)) {
l1_[i0].setBit(i1);
l2_[i0][i1].clear();
}
bool res = l2_[i0][i1].setBit(i2);
// Printf("%s: %zd => %zd %zd %zd; %d\n", __FUNCTION__,
// idx, i0, i1, i2, res);
return res;
}
bool clearBit(uptr idx) {
check(idx);
uptr i0 = idx0(idx);
uptr i1 = idx1(idx);
uptr i2 = idx2(idx);
bool res = false;
if (l1_[i0].getBit(i1)) {
res = l2_[i0][i1].clearBit(i2);
if (l2_[i0][i1].empty())
l1_[i0].clearBit(i1);
}
return res;
}
bool getBit(uptr idx) const {
check(idx);
uptr i0 = idx0(idx);
uptr i1 = idx1(idx);
uptr i2 = idx2(idx);
// Printf("%s: %zd => %zd %zd %zd\n", __FUNCTION__, idx, i0, i1, i2);
return l1_[i0].getBit(i1) && l2_[i0][i1].getBit(i2);
}
uptr getAndClearFirstOne() {
for (uptr i0 = 0; i0 < kLevel1Size; i0++) {
if (l1_[i0].empty()) continue;
uptr i1 = l1_[i0].getAndClearFirstOne();
uptr i2 = l2_[i0][i1].getAndClearFirstOne();
if (!l2_[i0][i1].empty())
l1_[i0].setBit(i1);
uptr res = i0 * BV::kSize * BV::kSize + i1 * BV::kSize + i2;
// Printf("getAndClearFirstOne: %zd %zd %zd => %zd\n", i0, i1, i2, res);
return res;
}
CHECK(0);
return 0;
}
// Do "this |= v" and return whether new bits have been added.
bool setUnion(const TwoLevelBitVector &v) {
bool res = false;
for (uptr i0 = 0; i0 < kLevel1Size; i0++) {
BV t = v.l1_[i0];
while (!t.empty()) {
uptr i1 = t.getAndClearFirstOne();
if (l1_[i0].setBit(i1))
l2_[i0][i1].clear();
if (l2_[i0][i1].setUnion(v.l2_[i0][i1]))
res = true;
}
}
return res;
}
void copyFrom(const TwoLevelBitVector &v) {
clear();
setUnion(v);
}
// Returns true if 'this' intersects with 'v'.
bool intersectsWith(const TwoLevelBitVector &v) const {
for (uptr i0 = 0; i0 < kLevel1Size; i0++) {
BV t = l1_[i0];
// FIXME: optimization: t &= v.l1_[i0]
while (!t.empty()) {
uptr i1 = t.getAndClearFirstOne();
if (!v.l1_[i0].getBit(i1)) continue;
if (l2_[i0][i1].intersectsWith(v.l2_[i0][i1]))
return true;
}
}
return false;
}
private:
void check(uptr idx) const { CHECK_LE(idx, size()); }
uptr idx0(uptr idx) const {
uptr res = idx / (BV::kSize * BV::kSize);
CHECK_LE(res, kLevel1Size);
return res;
}
uptr idx1(uptr idx) const {
uptr res = (idx / BV::kSize) % BV::kSize;
CHECK_LE(res, BV::kSize);
return res;
}
uptr idx2(uptr idx) const {
uptr res = idx % BV::kSize;
CHECK_LE(res, BV::kSize);
return res;
}
BV l1_[kLevel1Size];
BV l2_[kLevel1Size][BV::kSize];
};
} // namespace __sanitizer
#endif // SANITIZER_BITVECTOR_H
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