/// Calculate the magic number for unsigned division by a constant.
struct mu;
- mu magicu() const;
+ mu magicu(unsigned LeadingZeros = 0) const;
/// @}
/// @name Building-block Operations for APInt and APFloat
/// 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());
EXPECT_EQ(APInt(32, 5).magicu().s, 2U);
EXPECT_EQ(APInt(32, 7).magicu().m, APInt(32, "24924925", 16));
EXPECT_EQ(APInt(32, 7).magicu().s, 3U);
+ EXPECT_EQ(APInt(64, 25).magicu(1).m, APInt(64, "A3D70A3D70A3D70B", 16));
+ EXPECT_EQ(APInt(64, 25).magicu(1).s, 4U);
}
#ifdef GTEST_HAS_DEATH_TEST