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Add an argument to APInt's magic udiv calculation to specify the number of bits that are known zero in the divided number.

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This will come in handy soon.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127828 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Benjamin Kramer
2011-03-17 20:39:06 +00:00
parent 6a3dbd3b25
commit d9103df51b
3 changed files with 7 additions and 3 deletions
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6
lib/Support/APInt.cpp
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@ -1517,13 +1517,15 @@ APInt::ms APInt::magic() const {
/// division by a constant as a sequence of multiplies, adds and shifts.
/// Requires that the divisor not be 0. Taken from "Hacker's Delight", Henry
/// S. Warren, Jr., chapter 10.
APInt::mu APInt::magicu() const {
/// LeadingZeros can be used to simplify the calculation if the upper bits
/// of the devided value are known zero.
APInt::mu APInt::magicu(unsigned LeadingZeros) const {
const APInt& d = *this;
unsigned p;
APInt nc, delta, q1, r1, q2, r2;
struct mu magu;
magu.a = 0; // initialize "add" indicator
APInt allOnes = APInt::getAllOnesValue(d.getBitWidth());
APInt allOnes = APInt::getAllOnesValue(d.getBitWidth()).lshr(LeadingZeros);
APInt signedMin = APInt::getSignedMinValue(d.getBitWidth());
APInt signedMax = APInt::getSignedMaxValue(d.getBitWidth());