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Add countTrailingOnes member functions to APInt.

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llvm-svn: 47086
This commit is contained in:
Dan Gohman 2008-02-13 21:11:05 +00:00
parent 547ea0a60d
commit d22101a970
2 changed files with 24 additions and 2 deletions
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14
include/llvm/ADT/APInt.h
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@ -913,8 +913,9 @@ public:
/// one bits.
uint32_t countLeadingZeros() const;
/// countLeadingOnes - This function counts the number of contiguous 1 bits
/// in the high order bits. The count stops when the first 0 bit is reached.
/// countLeadingOnes - This function is an APInt version of the
/// countLeadingOnes_{32,64} functions in MathExtras.h. It counts the number
/// of ones from the most significant bit to the first zero bit.
/// @returns 0 if the high order bit is not set
/// @returns the number of 1 bits from the most significant to the least
/// @brief Count the number of leading one bits.
@ -929,6 +930,15 @@ public:
/// @brief Count the number of trailing zero bits.
uint32_t countTrailingZeros() const;
/// countTrailingOnes - This function is an APInt version of the
/// countTrailingOnes_{32,64} functions in MathExtras.h. It counts
/// the number of ones from the least significant bit to the first zero bit.
/// @returns BitWidth if the value is all ones.
/// @returns the number of ones from the least significant bit to the first
/// zero bit.
/// @brief Count the number of trailing one bits.
uint32_t countTrailingOnes() const;
/// countPopulation - This function is an APInt version of the
/// countPopulation_{32,64} functions in MathExtras.h. It counts the number
/// of 1 bits in the APInt value.

12
lib/Support/APInt.cpp
View File

@ -813,6 +813,18 @@ uint32_t APInt::countTrailingZeros() const {
return std::min(Count, BitWidth);
}
uint32_t APInt::countTrailingOnes() const {
if (isSingleWord())
return std::min(uint32_t(CountTrailingOnes_64(VAL)), BitWidth);
uint32_t Count = 0;
uint32_t i = 0;
for (; i < getNumWords() && pVal[i] == -1; ++i)
Count += APINT_BITS_PER_WORD;
if (i < getNumWords())
Count += CountTrailingOnes_64(pVal[i]);
return std::min(Count, BitWidth);
}
uint32_t APInt::countPopulation() const {
if (isSingleWord())
return CountPopulation_64(VAL);