Changes in directory llvm/include/llvm/ADT:
APInt.h updated: 1.26 -> 1.27
---
Log message:
Implement countLeadingOnes() and getMinSignedBits(). This helps to minimize
the bit width of negative numbers by computing the minimum bit width for a
negative value. E.g. 0x1800000000000000 could be just 0x8000000000000000
---
Diffs of the changes: (+14 -1)
APInt.h | 15 ++++++++++++++-
1 files changed, 14 insertions(+), 1 deletion(-)
Index: llvm/include/llvm/ADT/APInt.h
diff -u llvm/include/llvm/ADT/APInt.h:1.26 llvm/include/llvm/ADT/APInt.h:1.27
--- llvm/include/llvm/ADT/APInt.h:1.26 Tue Feb 27 14:24:31 2007
+++ llvm/include/llvm/ADT/APInt.h Tue Feb 27 15:59:26 2007
@@ -446,6 +446,12 @@
return BitWidth - countLeadingZeros();
}
+ inline uint32_t getMinSignedBits() const {
+ if (isNegative())
+ return BitWidth - countLeadingOnes() + 1;
+ return getActiveBits();
+ }
+
/// This method attempts to return the value of this APInt as a zero extended
/// uint64_t. The bitwidth must be <= 64 or the value must fit within a
/// uint64_t. Otherwise an assertion will result.
@@ -587,9 +593,16 @@
/// @returns getNumWords() * APINT_BITS_PER_WORD if the value is zero.
/// @returns the number of zeros from the most significant bit to the first
/// one bits.
- /// @brief Count the number of trailing one bits.
+ /// @brief Count the number of leading 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.
+ /// @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.
+ uint32_t countLeadingOnes() const;
+
/// countTrailingZeros - This function is an APInt version of the
/// countTrailingZoers_{32,64} functions in MathExtras.h. It counts
/// the number of zeros from the least significant bit to the first one bit.
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