From d9103df51b858cf051a1650ac7eb33d416e9ac41 Mon Sep 17 00:00:00 2001 From: Benjamin Kramer Date: Thu, 17 Mar 2011 20:39:06 +0000 Subject: Add an argument to APInt's magic udiv calculation to specify the number of bits that are known zero in the divided number. This will come in handy soon. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127828 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Support/APInt.cpp | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'lib/Support/APInt.cpp') 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()); -- cgit v1.2.3