Math.pow() doesn't constant folds when inputs are constant. For example, Math.pow(2, 1) should be replaced by `2`. This is not happening.

It was observed starting with JDK11. JDK 8 is approximately 20 times faster with constant base and exponent. This is likely a performance regression with JDK-8145688.

Additionally, strength reduction with Math.pow(x, 2.0D) => x*x introduced with JDK-8190869 does not work if the exponent only become a constant later during igvn. This should also be adressed.

This issue was noticed and reported by one of our customers.