// (icmp cond (sub A B) 0) -> ...
if (CI->isNullValue() && match(Op0, m_Sub(m_Value(A), m_Value(B)))) {
// (icmp cond A B) if cond is signed or equality
if (CmpInst::isSigned(I.getPredicate()) || I.isEquality())
return new ICmpInst(I.getPredicate(), A, B);
// (icmp ne A B) if cond is ugt
else if (I.getPredicate() == ICmpInst::ICMP_UGT)
return new ICmpInst(ICmpInst::ICMP_NE, A, B);
// (icmp eq A B) if cond is ULE
else if (I.getPredicate() == ICmpInst::ICMP_ULE)
return new ICmpInst(ICmpInst::ICMP_EQ, A, B);
}