The log10 usage added by JDK-8286800 causes build failures on SPARC (Oracle JDK 11u):
src/hotspot/share/opto/loopnode.cpp", line 4771: Error: Overloading ambiguity between "std::log10(double)" and "std::log10(float)".

For the backport to Oracle JDK 11u, I added a static_cast<double> of the argument. We should also fix this in mainline.

While browsing the code, I noticed that JDK-8283775 added a new implementation of "log10 rounded down" in node.cpp. I think we could simply use std::log10 there.