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[BitVector] Add find_[first,last]_[set,unset]_in.

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A lot of code is duplicated between the first_last and the
next / prev methods.  All of this code can be shared if they
are implemented in terms of find_first_in(Begin, End) etc,
in which case find_first = find_first_in(0, Size) and find_next
is find_first_in(Prev+1, Size), with similar reductions for
the other methods.

Differential Revision: https://reviews.llvm.org/D33104

llvm-svn: 303269
This commit is contained in:
Zachary Turner 2017-05-17 15:49:45 +00:00
parent 66f3d22962
commit 44e5728b1e
2 changed files with 292 additions and 119 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

256
include/llvm/ADT/BitVector.h
View File

@ -203,138 +203,164 @@ public:
return !any();
}
/// find_first - Returns the index of the first set bit, -1 if none
/// of the bits are set.
int find_first() const {
for (unsigned i = 0; i < NumBitWords(size()); ++i)
if (Bits[i] != 0)
return i * BITWORD_SIZE + countTrailingZeros(Bits[i]);
/// find_first_in - Returns the index of the first set bit in the range
/// [Begin, End). Returns -1 if all bits in the range are unset.
int find_first_in(unsigned Begin, unsigned End) const {
assert(Begin <= End && End <= Size);
if (Begin == End)
return -1;
unsigned FirstWord = Begin / BITWORD_SIZE;
unsigned LastWord = (End - 1) / BITWORD_SIZE;
// Check subsequent words.
for (unsigned i = FirstWord; i <= LastWord; ++i) {
BitWord Copy = Bits[i];
if (i == FirstWord) {
unsigned FirstBit = Begin % BITWORD_SIZE;
Copy &= maskTrailingZeros<BitWord>(FirstBit);
}
if (i == LastWord) {
unsigned LastBit = (End - 1) % BITWORD_SIZE;
Copy &= maskTrailingOnes<BitWord>(LastBit + 1);
}
if (Copy != 0)
return i * BITWORD_SIZE + countTrailingZeros(Copy);
}
return -1;
}
/// find_last_in - Returns the index of the last set bit in the range
/// [Begin, End). Returns -1 if all bits in the range are unset.
int find_last_in(unsigned Begin, unsigned End) const {
assert(Begin <= End && End <= Size);
if (Begin == End)
return -1;
unsigned LastWord = (End - 1) / BITWORD_SIZE;
unsigned FirstWord = Begin / BITWORD_SIZE;
for (unsigned i = LastWord + 1; i >= FirstWord + 1; --i) {
unsigned CurrentWord = i - 1;
BitWord Copy = Bits[CurrentWord];
if (CurrentWord == LastWord) {
unsigned LastBit = (End - 1) % BITWORD_SIZE;
Copy &= maskTrailingOnes<BitWord>(LastBit + 1);
}
if (CurrentWord == FirstWord) {
unsigned FirstBit = Begin % BITWORD_SIZE;
Copy &= maskTrailingZeros<BitWord>(FirstBit);
}
if (Copy != 0)
return (CurrentWord + 1) * BITWORD_SIZE - countLeadingZeros(Copy) - 1;
}
return -1;
}
/// find_first_unset_in - Returns the index of the first unset bit in the
/// range [Begin, End). Returns -1 if all bits in the range are set.
int find_first_unset_in(unsigned Begin, unsigned End) const {
assert(Begin <= End && End <= Size);
if (Begin == End)
return -1;
unsigned FirstWord = Begin / BITWORD_SIZE;
unsigned LastWord = (End - 1) / BITWORD_SIZE;
// Check subsequent words.
for (unsigned i = FirstWord; i <= LastWord; ++i) {
BitWord Copy = Bits[i];
if (i == FirstWord) {
unsigned FirstBit = Begin % BITWORD_SIZE;
Copy |= maskTrailingOnes<BitWord>(FirstBit);
}
if (i == LastWord) {
unsigned LastBit = (End - 1) % BITWORD_SIZE;
Copy |= maskTrailingZeros<BitWord>(LastBit + 1);
}
if (Copy != ~0UL) {
unsigned Result = i * BITWORD_SIZE + countTrailingOnes(Copy);
return Result < size() ? Result : -1;
}
}
return -1;
}
/// find_last_unset_in - Returns the index of the last unset bit in the
/// range [Begin, End). Returns -1 if all bits in the range are set.
int find_last_unset_in(unsigned Begin, unsigned End) const {
assert(Begin <= End && End <= Size);
if (Begin == End)
return -1;
unsigned LastWord = (End - 1) / BITWORD_SIZE;
unsigned FirstWord = Begin / BITWORD_SIZE;
for (unsigned i = LastWord + 1; i >= FirstWord + 1; --i) {
unsigned CurrentWord = i - 1;
BitWord Copy = Bits[CurrentWord];
if (CurrentWord == LastWord) {
unsigned LastBit = (End - 1) % BITWORD_SIZE;
Copy |= maskTrailingZeros<BitWord>(LastBit + 1);
}
if (CurrentWord == FirstWord) {
unsigned FirstBit = Begin % BITWORD_SIZE;
Copy |= maskTrailingOnes<BitWord>(FirstBit);
}
if (Copy != ~0UL) {
unsigned Result =
(CurrentWord + 1) * BITWORD_SIZE - countLeadingOnes(Copy) - 1;
return Result < Size ? Result : -1;
}
}
return -1;
}
/// find_first - Returns the index of the first set bit, -1 if none
/// of the bits are set.
int find_first() const { return find_first_in(0, Size); }
/// find_last - Returns the index of the last set bit, -1 if none of the bits
/// are set.
int find_last() const {
if (Size == 0)
return -1;
unsigned N = NumBitWords(size());
assert(N > 0);
unsigned i = N - 1;
while (i > 0 && Bits[i] == BitWord(0))
--i;
return int((i + 1) * BITWORD_SIZE - countLeadingZeros(Bits[i])) - 1;
}
/// find_first_unset - Returns the index of the first unset bit, -1 if all
/// of the bits are set.
int find_first_unset() const {
for (unsigned i = 0; i < NumBitWords(size()); ++i)
if (Bits[i] != ~0UL) {
unsigned Result = i * BITWORD_SIZE + countTrailingOnes(Bits[i]);
return Result < size() ? Result : -1;
}
return -1;
}
/// find_last_unset - Returns the index of the last unset bit, -1 if all of
/// the bits are set.
int find_last_unset() const {
if (Size == 0)
return -1;
const unsigned N = NumBitWords(size());
assert(N > 0);
unsigned i = N - 1;
BitWord W = Bits[i];
// The last word in the BitVector has some unused bits, so we need to set
// them all to 1 first. Set them all to 1 so they don't get treated as
// valid unset bits.
unsigned UnusedCount = BITWORD_SIZE - size() % BITWORD_SIZE;
W |= maskLeadingOnes<BitWord>(UnusedCount);
while (W == ~BitWord(0) && --i > 0)
W = Bits[i];
return int((i + 1) * BITWORD_SIZE - countLeadingOnes(W)) - 1;
}
int find_last() const { return find_last_in(0, Size); }
/// 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 {
++Prev;
if (Prev >= Size)
return -1;
int find_next(unsigned Prev) const { return find_first_in(Prev + 1, Size); }
unsigned WordPos = Prev / BITWORD_SIZE;
unsigned BitPos = Prev % BITWORD_SIZE;
BitWord Copy = Bits[WordPos];
// Mask off previous bits.
Copy &= maskTrailingZeros<BitWord>(BitPos);
/// find_prev - Returns the index of the first set bit that precedes the
/// the bit at \p PriorTo. Returns -1 if all previous bits are unset.
int find_prev(unsigned PriorTo) const { return find_last_in(0, PriorTo); }
if (Copy != 0)
return WordPos * BITWORD_SIZE + countTrailingZeros(Copy);
// Check subsequent words.
for (unsigned i = WordPos+1; i < NumBitWords(size()); ++i)
if (Bits[i] != 0)
return i * BITWORD_SIZE + countTrailingZeros(Bits[i]);
return -1;
}
/// find_first_unset - Returns the index of the first unset bit, -1 if all
/// of the bits are set.
int find_first_unset() const { return find_first_unset_in(0, Size); }
/// find_next_unset - Returns the index of the next unset bit following the
/// "Prev" bit. Returns -1 if all remaining bits are set.
int find_next_unset(unsigned Prev) const {
++Prev;
if (Prev >= Size)
return -1;
unsigned WordPos = Prev / BITWORD_SIZE;
unsigned BitPos = Prev % BITWORD_SIZE;
BitWord Copy = Bits[WordPos];
// Mask in previous bits.
BitWord Mask = (1 << BitPos) - 1;
Copy |= Mask;
if (Copy != ~0UL)
return next_unset_in_word(WordPos, Copy);
// Check subsequent words.
for (unsigned i = WordPos + 1; i < NumBitWords(size()); ++i)
if (Bits[i] != ~0UL)
return next_unset_in_word(i, Bits[i]);
return -1;
return find_first_unset_in(Prev + 1, Size);
}
/// find_prev - Returns the index of the first set bit that precedes the
/// the bit at \p PriorTo. Returns -1 if all previous bits are unset.
int find_prev(unsigned PriorTo) const {
if (PriorTo == 0)
return -1;
/// find_last_unset - Returns the index of the last unset bit, -1 if all of
/// the bits are set.
int find_last_unset() const { return find_last_unset_in(0, Size); }
--PriorTo;
unsigned WordPos = PriorTo / BITWORD_SIZE;
unsigned BitPos = PriorTo % BITWORD_SIZE;
BitWord Copy = Bits[WordPos];
// Mask off next bits.
Copy &= maskTrailingOnes<BitWord>(BitPos + 1);
if (Copy != 0)
return (WordPos + 1) * BITWORD_SIZE - countLeadingZeros(Copy) - 1;
// Check previous words.
for (unsigned i = 1; i <= WordPos; ++i) {
unsigned Index = WordPos - i;
if (Bits[Index] == 0)
continue;
return (Index + 1) * BITWORD_SIZE - countLeadingZeros(Bits[Index]) - 1;
}
return -1;
/// find_prev_unset - Returns the index of the first unset bit that precedes
/// the bit at \p PriorTo. Returns -1 if all previous bits are set.
int find_prev_unset(unsigned PriorTo) {
return find_last_unset_in(0, PriorTo);
}
/// clear - Removes all bits from the bitvector. Does not change capacity.

155
unittests/ADT/BitVectorTest.cpp
View File

@ -182,15 +182,13 @@ TYPED_TEST(BitVectorTest, TrivialOperation) {
EXPECT_TRUE(Vec.empty());
}
TYPED_TEST(BitVectorTest, FindOperations) {
TYPED_TEST(BitVectorTest, SimpleFindOps) {
// Test finding in an empty BitVector.
TypeParam A;
EXPECT_EQ(-1, A.find_first());
EXPECT_EQ(-1, A.find_last());
EXPECT_EQ(-1, A.find_first_unset());
EXPECT_EQ(-1, A.find_last_unset());
EXPECT_EQ(-1, A.find_next(0));
EXPECT_EQ(-1, A.find_next_unset(0));
// Test finding next set and unset bits in a BitVector with multiple words
A.resize(100);
@ -222,9 +220,10 @@ TYPED_TEST(BitVectorTest, FindOperations) {
A.set(0, 100);
EXPECT_EQ(100U, A.count());
EXPECT_EQ(0, A.find_first());
EXPECT_EQ(99, A.find_last());
EXPECT_EQ(-1, A.find_first_unset());
EXPECT_EQ(-1, A.find_last_unset());
EXPECT_EQ(99, A.find_last());
EXPECT_EQ(99, A.find_next(98));
A.reset(0, 100);
EXPECT_EQ(0U, A.count());
@ -232,6 +231,7 @@ TYPED_TEST(BitVectorTest, FindOperations) {
EXPECT_EQ(-1, A.find_last());
EXPECT_EQ(0, A.find_first_unset());
EXPECT_EQ(99, A.find_last_unset());
EXPECT_EQ(99, A.find_next_unset(98));
// Also test with a vector that is small enough to fit in 1 word.
A.resize(20);
@ -258,6 +258,153 @@ TYPED_TEST(BitVectorTest, FindOperations) {
EXPECT_EQ(17, A.find_next_unset(15));
}
TEST(BitVectorTest, FindInRangeMultiWord) {
BitVector Vec;
Vec.resize(200);
Vec.set(3, 7);
Vec.set(24, 35);
Vec.set(50, 70);
Vec.set(150);
Vec.set(152);
Vec.set(154);
// find first
EXPECT_EQ(-1, Vec.find_first_in(0, 0));
EXPECT_EQ(-1, Vec.find_first_in(24, 24));
EXPECT_EQ(-1, Vec.find_first_in(7, 24));
EXPECT_EQ(3, Vec.find_first_in(0, 10));
EXPECT_EQ(4, Vec.find_first_in(4, 10));
EXPECT_EQ(150, Vec.find_first_in(100, 200));
EXPECT_EQ(152, Vec.find_first_in(151, 200));
EXPECT_EQ(154, Vec.find_first_in(153, 200));
EXPECT_EQ(-1, Vec.find_first_in(155, 200));
Vec.set(199);
EXPECT_EQ(199, Vec.find_first_in(199, 200));
Vec.reset(199);
// find last
EXPECT_EQ(-1, Vec.find_last_in(0, 0));
EXPECT_EQ(-1, Vec.find_last_in(24, 24));
EXPECT_EQ(-1, Vec.find_last_in(7, 24));
EXPECT_EQ(6, Vec.find_last_in(0, 10));
EXPECT_EQ(5, Vec.find_last_in(0, 6));
EXPECT_EQ(154, Vec.find_last_in(100, 155));
EXPECT_EQ(152, Vec.find_last_in(100, 154));
EXPECT_EQ(150, Vec.find_last_in(100, 152));
EXPECT_EQ(-1, Vec.find_last_in(100, 150));
Vec.set(199);
EXPECT_EQ(199, Vec.find_last_in(199, 200));
Vec.reset(199);
// find first unset
EXPECT_EQ(-1, Vec.find_first_unset_in(0, 0));
EXPECT_EQ(-1, Vec.find_first_unset_in(23, 23));
EXPECT_EQ(-1, Vec.find_first_unset_in(24, 35));
EXPECT_EQ(0, Vec.find_first_unset_in(0, 10));
EXPECT_EQ(1, Vec.find_first_unset_in(1, 10));
EXPECT_EQ(7, Vec.find_first_unset_in(5, 25));
EXPECT_EQ(151, Vec.find_first_unset_in(150, 200));
EXPECT_EQ(151, Vec.find_first_unset_in(151, 200));
EXPECT_EQ(153, Vec.find_first_unset_in(152, 200));
EXPECT_EQ(153, Vec.find_first_unset_in(153, 200));
EXPECT_EQ(155, Vec.find_first_unset_in(154, 200));
EXPECT_EQ(155, Vec.find_first_unset_in(155, 200));
EXPECT_EQ(199, Vec.find_first_unset_in(199, 200));
// find last unset
EXPECT_EQ(-1, Vec.find_last_unset_in(0, 0));
EXPECT_EQ(-1, Vec.find_last_unset_in(23, 23));
EXPECT_EQ(-1, Vec.find_last_unset_in(24, 35));
EXPECT_EQ(9, Vec.find_last_unset_in(0, 10));
EXPECT_EQ(8, Vec.find_last_unset_in(0, 9));
EXPECT_EQ(2, Vec.find_last_unset_in(0, 7));
EXPECT_EQ(149, Vec.find_last_unset_in(100, 151));
EXPECT_EQ(151, Vec.find_last_unset_in(100, 152));
EXPECT_EQ(151, Vec.find_last_unset_in(100, 153));
EXPECT_EQ(153, Vec.find_last_unset_in(100, 154));
EXPECT_EQ(153, Vec.find_last_unset_in(100, 155));
EXPECT_EQ(155, Vec.find_last_unset_in(100, 156));
EXPECT_EQ(199, Vec.find_last_unset_in(199, 200));
}
TEST(BitVectorTest, FindInRangeSingleWord) {
// When the bit vector contains only a single word, this is slightly different
// than when the bit vector contains multiple words, because masks are applied
// to the front and back of the same word. So make sure this works.
BitVector Vec;
Vec.resize(25);
Vec.set(2, 4);
Vec.set(6, 9);
Vec.set(12, 15);
Vec.set(19);
Vec.set(21);
Vec.set(23);
// find first
EXPECT_EQ(-1, Vec.find_first_in(0, 0));
EXPECT_EQ(-1, Vec.find_first_in(24, 24));
EXPECT_EQ(-1, Vec.find_first_in(9, 12));
EXPECT_EQ(2, Vec.find_first_in(0, 10));
EXPECT_EQ(6, Vec.find_first_in(4, 10));
EXPECT_EQ(19, Vec.find_first_in(18, 25));
EXPECT_EQ(21, Vec.find_first_in(20, 25));
EXPECT_EQ(23, Vec.find_first_in(22, 25));
EXPECT_EQ(-1, Vec.find_first_in(24, 25));
// find last
EXPECT_EQ(-1, Vec.find_last_in(0, 0));
EXPECT_EQ(-1, Vec.find_last_in(24, 24));
EXPECT_EQ(-1, Vec.find_last_in(9, 12));
EXPECT_EQ(8, Vec.find_last_in(0, 10));
EXPECT_EQ(3, Vec.find_last_in(0, 6));
EXPECT_EQ(23, Vec.find_last_in(18, 25));
EXPECT_EQ(21, Vec.find_last_in(18, 23));
EXPECT_EQ(19, Vec.find_last_in(18, 21));
EXPECT_EQ(-1, Vec.find_last_in(18, 19));
// find first unset
EXPECT_EQ(-1, Vec.find_first_unset_in(0, 0));
EXPECT_EQ(-1, Vec.find_first_unset_in(23, 23));
EXPECT_EQ(-1, Vec.find_first_unset_in(6, 9));
EXPECT_EQ(0, Vec.find_first_unset_in(0, 6));
EXPECT_EQ(1, Vec.find_first_unset_in(1, 6));
EXPECT_EQ(9, Vec.find_first_unset_in(7, 13));
EXPECT_EQ(18, Vec.find_first_unset_in(18, 25));
EXPECT_EQ(20, Vec.find_first_unset_in(19, 25));
EXPECT_EQ(20, Vec.find_first_unset_in(20, 25));
EXPECT_EQ(22, Vec.find_first_unset_in(21, 25));
EXPECT_EQ(22, Vec.find_first_unset_in(22, 25));
EXPECT_EQ(24, Vec.find_first_unset_in(23, 25));
EXPECT_EQ(24, Vec.find_first_unset_in(24, 25));
// find last unset
EXPECT_EQ(-1, Vec.find_last_unset_in(0, 0));
EXPECT_EQ(-1, Vec.find_last_unset_in(23, 23));
EXPECT_EQ(-1, Vec.find_last_unset_in(6, 9));
EXPECT_EQ(5, Vec.find_last_unset_in(0, 6));
EXPECT_EQ(4, Vec.find_last_unset_in(0, 5));
EXPECT_EQ(1, Vec.find_last_unset_in(0, 4));
EXPECT_EQ(11, Vec.find_last_unset_in(7, 13));
EXPECT_EQ(24, Vec.find_last_unset_in(18, 25));
EXPECT_EQ(22, Vec.find_last_unset_in(18, 24));
EXPECT_EQ(22, Vec.find_last_unset_in(18, 23));
EXPECT_EQ(20, Vec.find_last_unset_in(18, 22));
EXPECT_EQ(20, Vec.find_last_unset_in(18, 21));
EXPECT_EQ(18, Vec.find_last_unset_in(18, 20));
EXPECT_EQ(18, Vec.find_last_unset_in(18, 19));
}
TYPED_TEST(BitVectorTest, CompoundAssignment) {
TypeParam A;
A.resize(10);