[llvm] 82f0e3d - Simplify BitVector code
via llvm-commits
llvm-commits at lists.llvm.org
Wed Apr 14 12:29:05 PDT 2021
Author: serge-sans-paille
Date: 2021-04-14T21:28:08+02:00
New Revision: 82f0e3d3ea6bf927e3397b2fb423abbc5821a30f
URL: https://github.com/llvm/llvm-project/commit/82f0e3d3ea6bf927e3397b2fb423abbc5821a30f
DIFF: https://github.com/llvm/llvm-project/commit/82f0e3d3ea6bf927e3397b2fb423abbc5821a30f.diff
LOG: Simplify BitVector code
Instead of managing memory by hand, delegate it to std::vector. This makes the
code much simpler, and also avoids repeatedly computing the storage size.
According to valgrind --tool=callgrind, this also slightly decreases the
instruction count, but by a small margin.
Differential Revision: https://reviews.llvm.org/D100387
Added:
Modified:
llvm/include/llvm/ADT/BitVector.h
Removed:
################################################################################
diff --git a/llvm/include/llvm/ADT/BitVector.h b/llvm/include/llvm/ADT/BitVector.h
index 080f9611678fc..1083510e3d691 100644
--- a/llvm/include/llvm/ADT/BitVector.h
+++ b/llvm/include/llvm/ADT/BitVector.h
@@ -79,14 +79,16 @@ class BitVector {
static_assert(BITWORD_SIZE == 64 || BITWORD_SIZE == 32,
"Unsupported word size");
- MutableArrayRef<BitWord> Bits; // Actual bits.
- unsigned Size; // Size of bitvector in bits.
+ using Storage = std::vector<BitWord>;
+
+ Storage Bits; // Actual bits.
+ unsigned Size; // Size of bitvector in bits.
public:
typedef unsigned size_type;
+
// Encapsulation of a single bit.
class reference {
- friend class BitVector;
BitWord *WordRef;
unsigned BitPos;
@@ -136,33 +138,12 @@ class BitVector {
/// BitVector ctor - Creates a bitvector of specified number of bits. All
/// bits are initialized to the specified value.
- explicit BitVector(unsigned s, bool t = false) : Size(s) {
- size_t Capacity = NumBitWords(s);
- Bits = allocate(Capacity);
- init_words(Bits, t);
+ explicit BitVector(unsigned s, bool t = false)
+ : Bits(NumBitWords(s), 0 - (BitWord)t), Size(s) {
if (t)
clear_unused_bits();
}
- /// BitVector copy ctor.
- BitVector(const BitVector &RHS) : Size(RHS.size()) {
- if (Size == 0) {
- Bits = MutableArrayRef<BitWord>();
- return;
- }
-
- size_t Capacity = NumBitWords(RHS.size());
- Bits = allocate(Capacity);
- std::memcpy(Bits.data(), RHS.Bits.data(), Capacity * sizeof(BitWord));
- }
-
- BitVector(BitVector &&RHS) : Bits(RHS.Bits), Size(RHS.Size) {
- RHS.Bits = MutableArrayRef<BitWord>();
- RHS.Size = 0;
- }
-
- ~BitVector() { std::free(Bits.data()); }
-
/// empty - Tests whether there are no bits in this bitvector.
bool empty() const { return Size == 0; }
@@ -172,17 +153,14 @@ class BitVector {
/// count - Returns the number of bits which are set.
size_type count() const {
unsigned NumBits = 0;
- for (unsigned i = 0; i < NumBitWords(size()); ++i)
- NumBits += countPopulation(Bits[i]);
+ for (auto Bit : Bits)
+ NumBits += countPopulation(Bit);
return NumBits;
}
/// any - Returns true if any bit is set.
bool any() const {
- for (unsigned i = 0; i < NumBitWords(size()); ++i)
- if (Bits[i] != 0)
- return true;
- return false;
+ return any_of(Bits, [](BitWord Bit) { return Bit != 0; });
}
/// all - Returns true if all bits are set.
@@ -348,43 +326,27 @@ class BitVector {
/// clear - Removes all bits from the bitvector. Does not change capacity.
void clear() {
Size = 0;
+ Bits.clear();
}
/// resize - Grow or shrink the bitvector.
void resize(unsigned N, bool t = false) {
- if (N > getBitCapacity()) {
- unsigned OldCapacity = Bits.size();
- grow(N);
- init_words(Bits.drop_front(OldCapacity), t);
- }
-
- // Set any old unused bits that are now included in the BitVector. This
- // may set bits that are not included in the new vector, but we will clear
- // them back out below.
- if (N > Size)
- set_unused_bits(t);
-
- // Update the size, and clear out any bits that are now unused
- unsigned OldSize = Size;
+ set_unused_bits(t);
Size = N;
- if (t || N < OldSize)
- clear_unused_bits();
+ Bits.resize(NumBitWords(N), 0 - BitWord(t));
+ clear_unused_bits();
}
- void reserve(unsigned N) {
- if (N > getBitCapacity())
- grow(N);
- }
+ void reserve(unsigned N) { Bits.reserve(NumBitWords(N)); }
// Set, reset, flip
BitVector &set() {
- init_words(Bits, true);
+ init_words(true);
clear_unused_bits();
return *this;
}
BitVector &set(unsigned Idx) {
- assert(Bits.data() && "Bits never allocated");
Bits[Idx / BITWORD_SIZE] |= BitWord(1) << (Idx % BITWORD_SIZE);
return *this;
}
@@ -419,7 +381,7 @@ class BitVector {
}
BitVector &reset() {
- init_words(Bits, false);
+ init_words(false);
return *this;
}
@@ -458,8 +420,8 @@ class BitVector {
}
BitVector &flip() {
- for (unsigned i = 0; i < NumBitWords(size()); ++i)
- Bits[i] = ~Bits[i];
+ for (auto &Bit : Bits)
+ Bit = ~Bit;
clear_unused_bits();
return *this;
}
@@ -504,8 +466,8 @@ class BitVector {
/// Test if any common bits are set.
bool anyCommon(const BitVector &RHS) const {
- unsigned ThisWords = NumBitWords(size());
- unsigned RHSWords = NumBitWords(RHS.size());
+ unsigned ThisWords = Bits.size();
+ unsigned RHSWords = RHS.Bits.size();
for (unsigned i = 0, e = std::min(ThisWords, RHSWords); i != e; ++i)
if (Bits[i] & RHS.Bits[i])
return true;
@@ -516,18 +478,16 @@ class BitVector {
bool operator==(const BitVector &RHS) const {
if (size() != RHS.size())
return false;
- unsigned NumWords = NumBitWords(size());
- return Bits.take_front(NumWords) == RHS.Bits.take_front(NumWords);
+ unsigned NumWords = Bits.size();
+ return std::equal(Bits.begin(), Bits.begin() + NumWords, RHS.Bits.begin());
}
- bool operator!=(const BitVector &RHS) const {
- return !(*this == RHS);
- }
+ bool operator!=(const BitVector &RHS) const { return !(*this == RHS); }
/// Intersection, union, disjoint union.
BitVector &operator&=(const BitVector &RHS) {
- unsigned ThisWords = NumBitWords(size());
- unsigned RHSWords = NumBitWords(RHS.size());
+ unsigned ThisWords = Bits.size();
+ unsigned RHSWords = RHS.Bits.size();
unsigned i;
for (i = 0; i != std::min(ThisWords, RHSWords); ++i)
Bits[i] &= RHS.Bits[i];
@@ -543,10 +503,9 @@ class BitVector {
/// reset - Reset bits that are set in RHS. Same as *this &= ~RHS.
BitVector &reset(const BitVector &RHS) {
- unsigned ThisWords = NumBitWords(size());
- unsigned RHSWords = NumBitWords(RHS.size());
- unsigned i;
- for (i = 0; i != std::min(ThisWords, RHSWords); ++i)
+ unsigned ThisWords = Bits.size();
+ unsigned RHSWords = RHS.Bits.size();
+ for (unsigned i = 0; i != std::min(ThisWords, RHSWords); ++i)
Bits[i] &= ~RHS.Bits[i];
return *this;
}
@@ -554,8 +513,8 @@ class BitVector {
/// test - Check if (This - RHS) is zero.
/// This is the same as reset(RHS) and any().
bool test(const BitVector &RHS) const {
- unsigned ThisWords = NumBitWords(size());
- unsigned RHSWords = NumBitWords(RHS.size());
+ unsigned ThisWords = Bits.size();
+ unsigned RHSWords = RHS.Bits.size();
unsigned i;
for (i = 0; i != std::min(ThisWords, RHSWords); ++i)
if ((Bits[i] & ~RHS.Bits[i]) != 0)
@@ -576,7 +535,7 @@ class BitVector {
[&Arg](auto const &BV) { return Arg.size() == BV; }) &&
"consistent sizes");
Out.resize(Arg.size());
- for (size_t i = 0, e = Out.NumBitWords(Arg.size()); i != e; ++i)
+ for (size_t i = 0, e = Arg.Bits.size(); i != e; ++i)
Out.Bits[i] = f(Arg.Bits[i], Args.Bits[i]...);
Out.clear_unused_bits();
return Out;
@@ -585,7 +544,7 @@ class BitVector {
BitVector &operator|=(const BitVector &RHS) {
if (size() < RHS.size())
resize(RHS.size());
- for (size_t i = 0, e = NumBitWords(RHS.size()); i != e; ++i)
+ for (size_t i = 0, e = RHS.Bits.size(); i != e; ++i)
Bits[i] |= RHS.Bits[i];
return *this;
}
@@ -593,7 +552,7 @@ class BitVector {
BitVector &operator^=(const BitVector &RHS) {
if (size() < RHS.size())
resize(RHS.size());
- for (size_t i = 0, e = NumBitWords(RHS.size()); i != e; ++i)
+ for (size_t i = 0, e = RHS.Bits.size(); i != e; ++i)
Bits[i] ^= RHS.Bits[i];
return *this;
}
@@ -603,7 +562,7 @@ class BitVector {
if (LLVM_UNLIKELY(empty() || N == 0))
return *this;
- unsigned NumWords = NumBitWords(Size);
+ unsigned NumWords = Bits.size();
assert(NumWords >= 1);
wordShr(N / BITWORD_SIZE);
@@ -652,7 +611,7 @@ class BitVector {
if (LLVM_UNLIKELY(empty() || N == 0))
return *this;
- unsigned NumWords = NumBitWords(Size);
+ unsigned NumWords = Bits.size();
assert(NumWords >= 1);
wordShl(N / BITWORD_SIZE);
@@ -697,53 +656,6 @@ class BitVector {
return *this;
}
- // Assignment operator.
- const BitVector &operator=(const BitVector &RHS) {
- if (this == &RHS) return *this;
-
- Size = RHS.size();
-
- // Handle tombstone when the BitVector is a key of a DenseHash.
- if (RHS.isInvalid()) {
- std::free(Bits.data());
- Bits = None;
- return *this;
- }
-
- unsigned RHSWords = NumBitWords(Size);
- if (Size <= getBitCapacity()) {
- if (Size)
- std::memcpy(Bits.data(), RHS.Bits.data(), RHSWords * sizeof(BitWord));
- clear_unused_bits();
- return *this;
- }
-
- // Grow the bitvector to have enough elements.
- unsigned NewCapacity = RHSWords;
- assert(NewCapacity > 0 && "negative capacity?");
- auto NewBits = allocate(NewCapacity);
- std::memcpy(NewBits.data(), RHS.Bits.data(), NewCapacity * sizeof(BitWord));
-
- // Destroy the old bits.
- std::free(Bits.data());
- Bits = NewBits;
-
- return *this;
- }
-
- const BitVector &operator=(BitVector &&RHS) {
- if (this == &RHS) return *this;
-
- std::free(Bits.data());
- Bits = RHS.Bits;
- Size = RHS.Size;
-
- RHS.Bits = MutableArrayRef<BitWord>();
- RHS.Size = 0;
-
- return *this;
- }
-
void swap(BitVector &RHS) {
std::swap(Bits, RHS.Bits);
std::swap(Size, RHS.Size);
@@ -755,9 +667,7 @@ class BitVector {
}
bool isInvalid() const { return Size == (unsigned)-1; }
- ArrayRef<BitWord> getData() const {
- return Bits.take_front(NumBitWords(size()));
- }
+ ArrayRef<BitWord> getData() const { return {&Bits[0], Bits.size()}; }
//===--------------------------------------------------------------------===//
// Portable bit mask operations.
@@ -807,23 +717,21 @@ class BitVector {
/// Example:
/// Words = [0xBBBBAAAA, 0xDDDDFFFF, 0x00000000, 0xDDDD0000]
/// represents a BitVector where 0xBBBBAAAA contain the least significant
- /// bits. So if we want to shift the BitVector left by 2 words, we need to
- /// turn this into 0x00000000 0x00000000 0xBBBBAAAA 0xDDDDFFFF by using a
+ /// bits. So if we want to shift the BitVector left by 2 words, we need
+ /// to turn this into 0x00000000 0x00000000 0xBBBBAAAA 0xDDDDFFFF by using a
/// memmove which moves right, not left.
void wordShl(uint32_t Count) {
if (Count == 0)
return;
- uint32_t NumWords = NumBitWords(Size);
-
- auto Src = Bits.take_front(NumWords).drop_back(Count);
- auto Dest = Bits.take_front(NumWords).drop_front(Count);
+ uint32_t NumWords = Bits.size();
// Since we always move Word-sized chunks of data with src and dest both
// aligned to a word-boundary, we don't need to worry about endianness
// here.
- std::memmove(Dest.begin(), Src.begin(), Dest.size() * sizeof(BitWord));
- std::memset(Bits.data(), 0, Count * sizeof(BitWord));
+ std::copy(Bits.begin(), Bits.begin() + NumWords - Count,
+ Bits.begin() + Count);
+ std::fill(Bits.begin(), Bits.begin() + Count, 0);
clear_unused_bits();
}
@@ -834,20 +742,10 @@ class BitVector {
if (Count == 0)
return;
- uint32_t NumWords = NumBitWords(Size);
-
- auto Src = Bits.take_front(NumWords).drop_front(Count);
- auto Dest = Bits.take_front(NumWords).drop_back(Count);
- assert(Dest.size() == Src.size());
+ uint32_t NumWords = Bits.size();
- std::memmove(Dest.begin(), Src.begin(), Dest.size() * sizeof(BitWord));
- std::memset(Dest.end(), 0, Count * sizeof(BitWord));
- }
-
- MutableArrayRef<BitWord> allocate(size_t NumWords) {
- BitWord *RawBits = static_cast<BitWord *>(
- safe_malloc(NumWords * sizeof(BitWord)));
- return MutableArrayRef<BitWord>(RawBits, NumWords);
+ std::copy(Bits.begin() + Count, Bits.begin() + NumWords, Bits.begin());
+ std::fill(Bits.begin() + NumWords - Count, Bits.begin() + NumWords, 0);
}
int next_unset_in_word(int WordIndex, BitWord Word) const {
@@ -861,19 +759,13 @@ class BitVector {
// Set the unused bits in the high words.
void set_unused_bits(bool t = true) {
- // Set high words first.
- unsigned UsedWords = NumBitWords(Size);
- if (Bits.size() > UsedWords)
- init_words(Bits.drop_front(UsedWords), t);
-
// Then set any stray high bits of the last used word.
- unsigned ExtraBits = Size % BITWORD_SIZE;
- if (ExtraBits) {
+ if (unsigned ExtraBits = Size % BITWORD_SIZE) {
BitWord ExtraBitMask = ~BitWord(0) << ExtraBits;
if (t)
- Bits[UsedWords-1] |= ExtraBitMask;
+ Bits.back() |= ExtraBitMask;
else
- Bits[UsedWords-1] &= ~ExtraBitMask;
+ Bits.back() &= ~ExtraBitMask;
}
}
@@ -882,18 +774,8 @@ class BitVector {
set_unused_bits(false);
}
- void grow(unsigned NewSize) {
- size_t NewCapacity = std::max<size_t>(NumBitWords(NewSize), Bits.size() * 2);
- assert(NewCapacity > 0 && "realloc-ing zero space");
- BitWord *NewBits = static_cast<BitWord *>(
- safe_realloc(Bits.data(), NewCapacity * sizeof(BitWord)));
- Bits = MutableArrayRef<BitWord>(NewBits, NewCapacity);
- clear_unused_bits();
- }
-
- void init_words(MutableArrayRef<BitWord> B, bool t) {
- if (B.size() > 0)
- memset(B.data(), 0 - (int)t, B.size() * sizeof(BitWord));
+ void init_words(bool t) {
+ std::fill(Bits.begin(), Bits.end(), 0 - (BitWord)t);
}
template<bool AddBits, bool InvertMask>
@@ -934,7 +816,7 @@ inline size_t capacity_in_bytes(const BitVector &X) {
}
template <> struct DenseMapInfo<BitVector> {
- static inline BitVector getEmptyKey() { return BitVector(); }
+ static inline BitVector getEmptyKey() { return {}; }
static inline BitVector getTombstoneKey() {
BitVector V;
V.invalid();
@@ -954,10 +836,7 @@ template <> struct DenseMapInfo<BitVector> {
namespace std {
/// Implement std::swap in terms of BitVector swap.
- inline void
- swap(llvm::BitVector &LHS, llvm::BitVector &RHS) {
- LHS.swap(RHS);
- }
+inline void swap(llvm::BitVector &LHS, llvm::BitVector &RHS) { LHS.swap(RHS); }
} // end namespace std
#endif // LLVM_ADT_BITVECTOR_H
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