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Add a getNumSignBits() method to APInt.

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llvm-svn: 126379
This commit is contained in:
Cameron Zwarich 2011-02-24 10:00:20 +00:00
parent e79a75febe
commit af4779907f
2 changed files with 7 additions and 6 deletions
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6
include/llvm/ADT/APInt.h
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@ -1193,6 +1193,12 @@ public:
/// @brief Count the number of leading one bits.
unsigned countLeadingOnes() const;
/// Computes the number of leading bits of this APInt that are equal to its
/// sign bit.
unsigned getNumSignBits() const {
return isNegative() ? countLeadingOnes() : countLeadingZeros();
}
/// countTrailingZeros - This function is an APInt version of the
/// countTrailingZeros_{32,64} functions in MathExtras.h. It counts
/// the number of zeros from the least significant bit to the first set bit.

7
lib/CodeGen/SelectionDAG/SelectionDAG.cpp
View File

@ -2088,12 +2088,7 @@ unsigned SelectionDAG::ComputeNumSignBits(SDValue Op, unsigned Depth) const{
case ISD::Constant: {
const APInt &Val = cast<ConstantSDNode>(Op)->getAPIntValue();
// If negative, return # leading ones.
if (Val.isNegative())
return Val.countLeadingOnes();
// Return # leading zeros.
return Val.countLeadingZeros();
return Val.getNumSignBits();
}
case ISD::SIGN_EXTEND: