diff options
| -rw-r--r-- | include/llvm/ADT/APInt.h | 2 | ||||
| -rw-r--r-- | lib/Support/APInt.cpp | 6 | ||||
| -rw-r--r-- | unittests/ADT/APIntTest.cpp | 2 |
3 files changed, 7 insertions, 3 deletions
diff --git a/include/llvm/ADT/APInt.h b/include/llvm/ADT/APInt.h index d1fd3e5034..82819d57a2 100644 --- a/include/llvm/ADT/APInt.h +++ b/include/llvm/ADT/APInt.h @@ -1372,7 +1372,7 @@ public: /// 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 diff --git a/lib/Support/APInt.cpp b/lib/Support/APInt.cpp index 08f36d2af3..f4aae72eca 100644 --- a/lib/Support/APInt.cpp +++ b/lib/Support/APInt.cpp @@ -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()); diff --git a/unittests/ADT/APIntTest.cpp b/unittests/ADT/APIntTest.cpp index e05bdbfc71..dbd0cb7a24 100644 --- a/unittests/ADT/APIntTest.cpp +++ b/unittests/ADT/APIntTest.cpp @@ -348,6 +348,8 @@ TEST(APIntTest, magicu) { 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 |