Magic data for optimising unsigned division by a constant. More...

#include "llvm/Support/DivisionByConstantInfo.h"

Static Public Member Functions
static UnsignedDivisionByConstantInfo	get (const APInt &D, unsigned LeadingZeros=0, bool AllowEvenDivisorOptimization=true)
	Calculate the magic numbers required to implement an unsigned integer division by a constant as a sequence of multiplies, adds and shifts.

Public Attributes
APInt	Magic
	magic number

bool	IsAdd
	add indicator

unsigned	PostShift
	post-shift amount

unsigned	PreShift
	pre-shift amount

Detailed Description

Magic data for optimising unsigned division by a constant.

Definition at line 28 of file DivisionByConstantInfo.h.

Member Function Documentation

◆ get()

UnsignedDivisionByConstantInfo UnsignedDivisionByConstantInfo::get	(	const APInt &	D,
		unsigned	LeadingZeros = `0`,
		bool	AllowEvenDivisorOptimization = `true`
	)

static

Calculate the magic numbers required to implement an unsigned integer 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. LeadingZeros can be used to simplify the calculation if the upper bits of the divided value are known zero.

Definition at line 74 of file DivisionByConstantInfo.cpp.

References llvm::AllOnes, assert(), D, get(), llvm::APInt::getAllOnes(), llvm::APInt::getSignedMaxValue(), llvm::APInt::getSignedMinValue(), IsAdd, llvm::APInt::isZero(), llvm::APInt::lshr(), Magic, NC, P, PostShift, PreShift, R2, llvm::APInt::udivrem(), llvm::APInt::uge(), and llvm::APInt::ult().