Add a SmallBitVector class, which mimics BitVector but uses only

a single pointer (PointerIntPair) member. In "small" mode, the
pointer field is reinterpreted as a set of bits. In "large" mode,
the pointer points to a heap-allocated object.

Also, give BitVector empty and swap functions.

And, add some simple unittests for BitVector and SmallBitVector.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@92730 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman 2010-01-05 15:04:49 +00:00
parent eade002094
commit cb89afc965
4 changed files with 671 additions and 0 deletions

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@ -95,6 +95,9 @@ public:
delete[] Bits;
}
/// empty - Tests whether there are no bits in this bitvector.
bool empty() const { return Size == 0; }
/// size - Returns the number of bits in this bitvector.
unsigned size() const { return Size; }
@ -341,6 +344,12 @@ public:
return *this;
}
void swap(BitVector &RHS) {
std::swap(Bits, RHS.Bits);
std::swap(Size, RHS.Size);
std::swap(Capacity, RHS.Capacity);
}
private:
unsigned NumBitWords(unsigned S) const {
return (S + BITWORD_SIZE-1) / BITWORD_SIZE;
@ -406,4 +415,13 @@ inline BitVector operator^(const BitVector &LHS, const BitVector &RHS) {
}
} // End llvm namespace
namespace std {
/// Implement std::swap in terms of BitVector swap.
inline void
swap(llvm::BitVector &LHS, llvm::BitVector &RHS) {
LHS.swap(RHS);
}
}
#endif

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@ -0,0 +1,373 @@
//===- llvm/ADT/SmallBitVector.h - 'Normally small' bit vectors -*- C++ -*-===//
//
// 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 SmallBitVector class.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_ADT_SMALLBITVECTOR_H
#define LLVM_ADT_SMALLBITVECTOR_H
#include "llvm/ADT/BitVector.h"
#include "llvm/ADT/PointerIntPair.h"
#include "llvm/Support/MathExtras.h"
#include <cassert>
namespace llvm {
/// SmallBitVector - This is a 'bitvector' (really, a variable-sized bit array),
/// optimized for the case when the array is small. It contains one
/// pointer-sized field, which is directly used as a plain collection of bits
/// when possible, or as a pointer to a larger heap-allocated array when
/// necessary. This allows normal "small" cases to be fast without losing
/// generality for large inputs.
///
class SmallBitVector {
// TODO: In "large" mode, a pointer to a BitVector is used, leading to an
// unnecessary level of indirection. It would be more efficient to use a
// pointer to memory containing size, allocation size, and the array of bits.
PointerIntPair<BitVector *, 1, uintptr_t> X;
// The number of bits in this class.
static const size_t NumBaseBits = sizeof(X) * CHAR_BIT;
// One bit is used to discriminate between small and large mode. The
// remaining bits are used for the small-mode representation.
static const size_t SmallNumRawBits = NumBaseBits - 1;
// A few more bits are used to store the size of the bit set in small mode.
// Theoretically this is a ceil-log2. These bits are encoded in the most
// significant bits of the raw bits.
static const size_t SmallNumSizeBits = (NumBaseBits == 32 ? 5 :
NumBaseBits == 64 ? 6 :
SmallNumRawBits);
// The remaining bits are used to store the actual set in small mode.
static const size_t SmallNumDataBits = SmallNumRawBits - SmallNumSizeBits;
bool isSmall() const {
return X.getInt();
}
void switchToSmall(uintptr_t NewSmallBits, size_t NewSize) {
X.setInt(true);
setSmallSize(NewSize);
setSmallBits(NewSmallBits);
}
void switchToLarge(BitVector *BV) {
X.setInt(false);
X.setPointer(BV);
}
// Return all the bits used for the "small" representation; this includes
// bits for the size as well as the element bits.
uintptr_t getSmallRawBits() const {
return reinterpret_cast<uintptr_t>(X.getPointer()) >> 1;
}
void setSmallRawBits(uintptr_t NewRawBits) {
return X.setPointer(reinterpret_cast<BitVector *>(NewRawBits << 1));
}
// Return the size.
size_t getSmallSize() const {
return getSmallRawBits() >> SmallNumDataBits;
}
void setSmallSize(size_t Size) {
setSmallRawBits(getSmallBits() | (Size << SmallNumDataBits));
}
// Return the element bits.
uintptr_t getSmallBits() const {
return getSmallRawBits() & ~(~uintptr_t(0) << SmallNumDataBits);
}
void setSmallBits(uintptr_t NewBits) {
setSmallRawBits((getSmallRawBits() & (~uintptr_t(0) << SmallNumDataBits)) |
(NewBits & ~(~uintptr_t(0) << getSmallSize())));
}
public:
/// SmallBitVector default ctor - Creates an empty bitvector.
SmallBitVector() : X(0, 1) {}
/// SmallBitVector ctor - Creates a bitvector of specified number of bits. All
/// bits are initialized to the specified value.
explicit SmallBitVector(unsigned s, bool t = false) : X(0, 1) {
if (s <= SmallNumRawBits)
switchToSmall(t ? ~uintptr_t(0) : 0, s);
else
switchToLarge(new BitVector(s, t));
}
/// SmallBitVector copy ctor.
SmallBitVector(const SmallBitVector &RHS) {
if (RHS.isSmall())
X = RHS.X;
else
switchToLarge(new BitVector(*RHS.X.getPointer()));
}
~SmallBitVector() {
if (!isSmall())
delete X.getPointer();
}
/// empty - Tests whether there are no bits in this bitvector.
bool empty() const {
return isSmall() ? getSmallSize() == 0 : X.getPointer()->empty();
}
/// size - Returns the number of bits in this bitvector.
size_t size() const {
return isSmall() ? getSmallSize() : X.getPointer()->size();
}
/// count - Returns the number of bits which are set.
unsigned count() const {
if (isSmall()) {
uintptr_t Bits = getSmallBits();
if (sizeof(uintptr_t) * CHAR_BIT == 32)
return CountPopulation_32(Bits);
if (sizeof(uintptr_t) * CHAR_BIT == 64)
return CountPopulation_64(Bits);
assert(0 && "Unsupported!");
}
return X.getPointer()->count();
}
/// any - Returns true if any bit is set.
bool any() const {
if (isSmall())
return getSmallBits() != 0;
return X.getPointer()->any();
}
/// none - Returns true if none of the bits are set.
bool none() const {
if (isSmall())
return getSmallBits() == 0;
return X.getPointer()->none();
}
/// find_first - Returns the index of the first set bit, -1 if none
/// of the bits are set.
int find_first() const {
if (isSmall()) {
uintptr_t Bits = getSmallBits();
if (sizeof(uintptr_t) * CHAR_BIT == 32)
return CountTrailingZeros_32(Bits);
if (sizeof(uintptr_t) * CHAR_BIT == 64)
return CountTrailingZeros_64(Bits);
assert(0 && "Unsupported!");
}
return X.getPointer()->find_first();
}
/// find_next - Returns the index of the next set bit following the
/// "Prev" bit. Returns -1 if the next set bit is not found.
int find_next(unsigned Prev) const {
if (isSmall()) {
uintptr_t Bits = getSmallBits();
// Mask off previous bits.
Bits &= ~uintptr_t(0) << Prev;
if (sizeof(uintptr_t) * CHAR_BIT == 32)
return CountTrailingZeros_32(Bits);
if (sizeof(uintptr_t) * CHAR_BIT == 64)
return CountTrailingZeros_64(Bits);
assert(0 && "Unsupported!");
}
return X.getPointer()->find_next(Prev);
}
/// clear - Clear all bits.
void clear() {
if (!isSmall())
delete X.getPointer();
switchToSmall(0, 0);
}
/// resize - Grow or shrink the bitvector.
void resize(unsigned N, bool t = false) {
if (!isSmall()) {
X.getPointer()->resize(N, t);
} else if (getSmallSize() >= N) {
setSmallSize(N);
setSmallBits(getSmallBits());
} else {
BitVector *BV = new BitVector(N, t);
uintptr_t OldBits = getSmallBits();
for (size_t i = 0, e = getSmallSize(); i != e; ++i)
(*BV)[i] = (OldBits >> i) & 1;
switchToLarge(BV);
}
}
void reserve(unsigned N) {
if (isSmall()) {
if (N > SmallNumDataBits) {
uintptr_t OldBits = getSmallRawBits();
size_t SmallSize = getSmallSize();
BitVector *BV = new BitVector(SmallSize);
for (size_t i = 0; i < SmallSize; ++i)
if ((OldBits >> i) & 1)
BV->set(i);
BV->reserve(N);
switchToLarge(BV);
}
} else {
X.getPointer()->reserve(N);
}
}
// Set, reset, flip
SmallBitVector &set() {
if (isSmall())
setSmallBits(~uintptr_t(0));
else
X.getPointer()->set();
return *this;
}
SmallBitVector &set(unsigned Idx) {
if (isSmall())
setSmallBits(getSmallBits() | (uintptr_t(1) << Idx));
else
X.getPointer()->set(Idx);
return *this;
}
SmallBitVector &reset() {
if (isSmall())
setSmallBits(0);
else
X.getPointer()->reset();
return *this;
}
SmallBitVector &reset(unsigned Idx) {
if (isSmall())
setSmallBits(getSmallBits() & ~(uintptr_t(1) << Idx));
else
X.getPointer()->reset(Idx);
return *this;
}
SmallBitVector &flip() {
if (isSmall())
setSmallBits(~getSmallBits());
else
X.getPointer()->flip();
return *this;
}
SmallBitVector &flip(unsigned Idx) {
if (isSmall())
setSmallBits(getSmallBits() ^ (uintptr_t(1) << Idx));
else
X.getPointer()->flip(Idx);
return *this;
}
// No argument flip.
SmallBitVector operator~() const {
return SmallBitVector(*this).flip();
}
// Indexing.
// TODO: Add an index operator which returns a "reference" (proxy class).
bool operator[](unsigned Idx) const {
assert(Idx < size() && "Out-of-bounds Bit access.");
if (isSmall())
return ((getSmallBits() >> Idx) & 1) != 0;
return X.getPointer()->operator[](Idx);
}
bool test(unsigned Idx) const {
return (*this)[Idx];
}
// Comparison operators.
bool operator==(const SmallBitVector &RHS) const {
if (size() != RHS.size())
return false;
if (isSmall())
return getSmallBits() == RHS.getSmallBits();
else
return *X.getPointer() == *RHS.X.getPointer();
}
bool operator!=(const SmallBitVector &RHS) const {
return !(*this == RHS);
}
// Intersection, union, disjoint union.
BitVector &operator&=(const SmallBitVector &RHS); // TODO: implement
BitVector &operator|=(const SmallBitVector &RHS); // TODO: implement
BitVector &operator^=(const SmallBitVector &RHS); // TODO: implement
// Assignment operator.
const SmallBitVector &operator=(const SmallBitVector &RHS) {
if (isSmall()) {
if (RHS.isSmall())
X = RHS.X;
else
switchToLarge(new BitVector(*RHS.X.getPointer()));
} else {
if (!RHS.isSmall())
*X.getPointer() = *RHS.X.getPointer();
else {
delete X.getPointer();
X = RHS.X;
}
}
return *this;
}
void swap(SmallBitVector &RHS) {
std::swap(X, RHS.X);
}
};
inline SmallBitVector
operator&(const SmallBitVector &LHS, const SmallBitVector &RHS) {
SmallBitVector Result(LHS);
Result &= RHS;
return Result;
}
inline SmallBitVector
operator|(const SmallBitVector &LHS, const SmallBitVector &RHS) {
SmallBitVector Result(LHS);
Result |= RHS;
return Result;
}
inline SmallBitVector
operator^(const SmallBitVector &LHS, const SmallBitVector &RHS) {
SmallBitVector Result(LHS);
Result ^= RHS;
return Result;
}
} // End llvm namespace
namespace std {
/// Implement std::swap in terms of BitVector swap.
inline void
swap(llvm::SmallBitVector &LHS, llvm::SmallBitVector &RHS) {
LHS.swap(RHS);
}
}
#endif

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@ -0,0 +1,140 @@
//===- llvm/unittest/ADT/BitVectorTest.cpp - BitVector tests --------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "llvm/ADT/BitVector.h"
#include "gtest/gtest.h"
using namespace llvm;
namespace {
TEST(BitVectorTest, TrivialOperation) {
BitVector Vec;
EXPECT_EQ(0U, Vec.count());
EXPECT_EQ(0U, Vec.size());
EXPECT_FALSE(Vec.any());
EXPECT_TRUE(Vec.none());
EXPECT_TRUE(Vec.empty());
Vec.resize(5, true);
EXPECT_EQ(5U, Vec.count());
EXPECT_EQ(5U, Vec.size());
EXPECT_TRUE(Vec.any());
EXPECT_FALSE(Vec.none());
EXPECT_FALSE(Vec.empty());
Vec.resize(11);
EXPECT_EQ(5U, Vec.count());
EXPECT_EQ(11U, Vec.size());
EXPECT_TRUE(Vec.any());
EXPECT_FALSE(Vec.none());
EXPECT_FALSE(Vec.empty());
BitVector Inv = ~Vec;
EXPECT_EQ(6U, Inv.count());
EXPECT_EQ(11U, Inv.size());
EXPECT_TRUE(Inv.any());
EXPECT_FALSE(Inv.none());
EXPECT_FALSE(Inv.empty());
EXPECT_FALSE(Inv == Vec);
EXPECT_TRUE(Inv != Vec);
Vec = ~Vec;
EXPECT_TRUE(Inv == Vec);
EXPECT_FALSE(Inv != Vec);
// Add some "interesting" data to Vec.
Vec.resize(23, true);
Vec.resize(25, false);
Vec.resize(26, true);
Vec.resize(29, false);
Vec.resize(33, true);
Vec.resize(61, false);
unsigned Count = 0;
for (unsigned i = Vec.find_first(); i != -1u; i = Vec.find_next(i)) {
++Count;
EXPECT_TRUE(Vec[i]);
EXPECT_TRUE(Vec.test(i));
}
EXPECT_EQ(Count, Vec.count());
EXPECT_EQ(Count, 23u);
EXPECT_FALSE(Vec[0]);
EXPECT_TRUE(Vec[32]);
EXPECT_FALSE(Vec[60]);
BitVector Copy = Vec;
BitVector Alt(3, false);
Alt.resize(6, true);
std::swap(Alt, Vec);
EXPECT_TRUE(Copy == Alt);
EXPECT_TRUE(Vec.size() == 6);
EXPECT_TRUE(Vec.count() == 3);
EXPECT_TRUE(Vec.find_first() == 3);
std::swap(Copy, Vec);
// Add some more "interesting" data.
Vec.resize(68, true);
Vec.resize(78, false);
Vec.resize(89, true);
Vec.resize(90, false);
Vec.resize(91, true);
Vec.resize(130, false);
Count = 0;
for (unsigned i = Vec.find_first(); i != -1u; i = Vec.find_next(i)) {
++Count;
EXPECT_TRUE(Vec[i]);
EXPECT_TRUE(Vec.test(i));
}
EXPECT_EQ(Count, Vec.count());
EXPECT_EQ(Count, 42u);
EXPECT_FALSE(Vec[0]);
EXPECT_TRUE(Vec[32]);
EXPECT_FALSE(Vec[60]);
EXPECT_FALSE(Vec[129]);
Vec.flip(60);
EXPECT_TRUE(Vec[60]);
EXPECT_EQ(Count + 1, Vec.count());
Vec.flip(60);
EXPECT_FALSE(Vec[60]);
EXPECT_EQ(Count, Vec.count());
Vec.reset(32);
EXPECT_FALSE(Vec[32]);
EXPECT_EQ(Count - 1, Vec.count());
Vec.set(32);
EXPECT_TRUE(Vec[32]);
EXPECT_EQ(Count, Vec.count());
Vec.flip();
EXPECT_EQ(Vec.size() - Count, Vec.count());
Vec.reset();
EXPECT_EQ(0U, Vec.count());
EXPECT_EQ(130U, Vec.size());
EXPECT_FALSE(Vec.any());
EXPECT_TRUE(Vec.none());
EXPECT_FALSE(Vec.empty());
Inv = ~BitVector();
EXPECT_EQ(0U, Inv.count());
EXPECT_EQ(0U, Inv.size());
EXPECT_FALSE(Inv.any());
EXPECT_TRUE(Inv.none());
EXPECT_TRUE(Inv.empty());
Vec.clear();
EXPECT_EQ(0U, Vec.count());
EXPECT_EQ(0U, Vec.size());
EXPECT_FALSE(Vec.any());
EXPECT_TRUE(Vec.none());
EXPECT_TRUE(Vec.empty());
}
}

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@ -0,0 +1,140 @@
//===- llvm/unittest/ADT/SmallBitVectorTest.cpp - SmallBitVector tests ----===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "llvm/ADT/SmallBitVector.h"
#include "gtest/gtest.h"
using namespace llvm;
namespace {
TEST(SmallBitVectorTest, TrivialOperation) {
SmallBitVector Vec;
EXPECT_EQ(0U, Vec.count());
EXPECT_EQ(0U, Vec.size());
EXPECT_FALSE(Vec.any());
EXPECT_TRUE(Vec.none());
EXPECT_TRUE(Vec.empty());
Vec.resize(5, true);
EXPECT_EQ(5U, Vec.count());
EXPECT_EQ(5U, Vec.size());
EXPECT_TRUE(Vec.any());
EXPECT_FALSE(Vec.none());
EXPECT_FALSE(Vec.empty());
Vec.resize(11);
EXPECT_EQ(5U, Vec.count());
EXPECT_EQ(11U, Vec.size());
EXPECT_TRUE(Vec.any());
EXPECT_FALSE(Vec.none());
EXPECT_FALSE(Vec.empty());
SmallBitVector Inv = ~Vec;
EXPECT_EQ(6U, Inv.count());
EXPECT_EQ(11U, Inv.size());
EXPECT_TRUE(Inv.any());
EXPECT_FALSE(Inv.none());
EXPECT_FALSE(Inv.empty());
EXPECT_FALSE(Inv == Vec);
EXPECT_TRUE(Inv != Vec);
Vec = ~Vec;
EXPECT_TRUE(Inv == Vec);
EXPECT_FALSE(Inv != Vec);
// Add some "interesting" data to Vec.
Vec.resize(23, true);
Vec.resize(25, false);
Vec.resize(26, true);
Vec.resize(29, false);
Vec.resize(33, true);
Vec.resize(61, false);
unsigned Count = 0;
for (unsigned i = Vec.find_first(); i != -1u; i = Vec.find_next(i)) {
++Count;
EXPECT_TRUE(Vec[i]);
EXPECT_TRUE(Vec.test(i));
}
EXPECT_EQ(Count, Vec.count());
EXPECT_EQ(Count, 23u);
EXPECT_FALSE(Vec[0]);
EXPECT_TRUE(Vec[32]);
EXPECT_FALSE(Vec[60]);
SmallBitVector Copy = Vec;
SmallBitVector Alt(3, false);
Alt.resize(6, true);
std::swap(Alt, Vec);
EXPECT_TRUE(Copy == Alt);
EXPECT_TRUE(Vec.size() == 6);
EXPECT_TRUE(Vec.count() == 3);
EXPECT_TRUE(Vec.find_first() == 3);
std::swap(Copy, Vec);
// Add some more "interesting" data.
Vec.resize(68, true);
Vec.resize(78, false);
Vec.resize(89, true);
Vec.resize(90, false);
Vec.resize(91, true);
Vec.resize(130, false);
Count = 0;
for (unsigned i = Vec.find_first(); i != -1u; i = Vec.find_next(i)) {
++Count;
EXPECT_TRUE(Vec[i]);
EXPECT_TRUE(Vec.test(i));
}
EXPECT_EQ(Count, Vec.count());
EXPECT_EQ(Count, 42u);
EXPECT_FALSE(Vec[0]);
EXPECT_TRUE(Vec[32]);
EXPECT_FALSE(Vec[60]);
EXPECT_FALSE(Vec[129]);
Vec.flip(60);
EXPECT_TRUE(Vec[60]);
EXPECT_EQ(Count + 1, Vec.count());
Vec.flip(60);
EXPECT_FALSE(Vec[60]);
EXPECT_EQ(Count, Vec.count());
Vec.reset(32);
EXPECT_FALSE(Vec[32]);
EXPECT_EQ(Count - 1, Vec.count());
Vec.set(32);
EXPECT_TRUE(Vec[32]);
EXPECT_EQ(Count, Vec.count());
Vec.flip();
EXPECT_EQ(Vec.size() - Count, Vec.count());
Vec.reset();
EXPECT_EQ(0U, Vec.count());
EXPECT_EQ(130U, Vec.size());
EXPECT_FALSE(Vec.any());
EXPECT_TRUE(Vec.none());
EXPECT_FALSE(Vec.empty());
Inv = ~SmallBitVector();
EXPECT_EQ(0U, Inv.count());
EXPECT_EQ(0U, Inv.size());
EXPECT_FALSE(Inv.any());
EXPECT_TRUE(Inv.none());
EXPECT_TRUE(Inv.empty());
Vec.clear();
EXPECT_EQ(0U, Vec.count());
EXPECT_EQ(0U, Vec.size());
EXPECT_FALSE(Vec.any());
EXPECT_TRUE(Vec.none());
EXPECT_TRUE(Vec.empty());
}
}