浮点数相除

            // Replace "val / dcon" with "val * (1.0 / dcon)" if dcon is a power of two.
            // Powers of two within range are always exactly represented,
            // so multiplication by the reciprocal is safe in this scenario
             if (fgGlobalMorph && op2->IsCnsFltOrDbl())
            {
                double divisor = op2->AsDblCon()->DconValue();
                if (((typ == TYP_DOUBLE) && FloatingPointUtils::hasPreciseReciprocal(divisor)) ||
                    ((typ == TYP_FLOAT) && FloatingPointUtils::hasPreciseReciprocal(forceCastToFloat(divisor))))
                {
                    oper = GT_MUL;
                    tree->ChangeOper(oper);
                    op2->AsDblCon()->SetDconValue(1.0 / divisor);
                }
            }

GenTree* Compiler::fgMorphSmpOp
当除数是一个浮点型立即数时GT_DIV改为GT_MUL （1/divisor），[https://github.com/dotnet/runtime/blob/main/src/coreclr/jit/morph.cpp]

当除数是2的幂时可以优化

将除法改为右移 a%b可以替换为 a & （b-1） 在低级化lowerconstdivormod

   if (isDiv)
    {
        // perform the division by right shifting the adjusted dividend
        divisor->AsIntCon()->SetIconValue(genLog2(absDivisorValue));

        newDivMod = comp->gtNewOperNode(GT_RSH, type, adjustedDividend, divisor);
        ContainCheckShiftRotate(newDivMod->AsOp());

        if (divisorValue < 0)
        {
            // negate the result if the divisor is negative
            newDivMod = comp->gtNewOperNode(GT_NEG, type, newDivMod);
            ContainCheckNode(newDivMod);
        }
    }
    else
    {
        // divisor % dividend = dividend - divisor x (dividend / divisor)
        // divisor x (dividend / divisor) translates to (dividend >> log2(divisor)) << log2(divisor)
        // which simply discards the low log2(divisor) bits, that's just dividend & ~(divisor - 1)
        divisor->AsIntCon()->SetIconValue(~(absDivisorValue - 1));

        newDivMod = comp->gtNewOperNode(GT_SUB, type,
                                        comp->gtNewLclvNode(dividend->AsLclVar()->GetLclNum(), dividend->TypeGet()),
                                        comp->gtNewOperNode(GT_AND, type, adjustedDividend, divisor));
    }

    // Remove the divisor and dividend nodes from the linear order,
    // since we have reused them and will resequence the tree
    BlockRange().Remove(divisor);
    BlockRange().Remove(dividend);

    // linearize and insert the new tree before the original divMod node
    InsertTreeBeforeAndContainCheck(divMod, newDivMod);
    BlockRange().Remove(divMod);

    // replace the original divmod node with the new divmod tree
    use.ReplaceWith(newDivMod);

    *nextNode = newDivMod->gtNext;
    return true;
}