diff options
| -rw-r--r-- | include/llvm/ADT/BitVector.h | 37 |
1 files changed, 26 insertions, 11 deletions
diff --git a/include/llvm/ADT/BitVector.h b/include/llvm/ADT/BitVector.h index 243a8102cf..50ccdab159 100644 --- a/include/llvm/ADT/BitVector.h +++ b/include/llvm/ADT/BitVector.h @@ -186,13 +186,17 @@ public: init_words(&Bits[OldCapacity], (Capacity-OldCapacity), t); } - // If we previously had no size, initialize the low word - if (Size == 0) - for (unsigned i = 0; i < Capacity; ++i) - Bits[i] = 0 - (unsigned)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; Size = N; - clear_unused_bits(); + if (t || N < OldSize) + clear_unused_bits(); } void reserve(unsigned N) { @@ -303,7 +307,7 @@ public: } // Grow the bitvector to have enough elements. - Capacity = NumBitWords(Size); + Capacity = RHSWords; BitWord *NewBits = new BitWord[Capacity]; std::copy(RHS.Bits, &RHS.Bits[RHSWords], NewBits); @@ -318,16 +322,27 @@ private: unsigned NumBitWords(unsigned S) const { return (S + BITWORD_SIZE-1) / BITWORD_SIZE; } - - // Clear the unused top bits in the high word. - void clear_unused_bits() { + + // Set the unused bits in the high words. + void set_unused_bits(bool t = true) { + // Set high words first. + unsigned UsedWords = NumBitWords(Size); + if (Capacity > UsedWords) + init_words(&Bits[UsedWords], (Capacity-UsedWords), t); + + // Then set any stray high bits of the last used word. unsigned ExtraBits = Size % BITWORD_SIZE; if (ExtraBits) { - unsigned index = Size / BITWORD_SIZE; - Bits[index] &= ~(~0L << ExtraBits); + Bits[UsedWords-1] &= ~(~0L << ExtraBits); + Bits[UsedWords-1] |= (0 - (BitWord)t) << ExtraBits; } } + // Clear the unused bits in the high words. + void clear_unused_bits() { + set_unused_bits(false); + } + void grow(unsigned NewSize) { unsigned OldCapacity = Capacity; Capacity = NumBitWords(NewSize); |