I checked in the latest jdk master and both cbrt / acos are NOT intrinsics.
However, cbrt(x) = pow(x, 1/3) so it may be optmized... Could someone tell me how cbrt() is concretely implemented ? In native libfdm, there is no e_cbrt.c ! Thanks for your help, Laurent Le 9 nov. 2017 10:52 AM, "Jonas Konrad" <m...@yawk.at> a écrit : > Hey, > > Most functions in the Math class are intrinsic ( > http://hg.openjdk.java.net/jdk8u/jdk8u/hotspot/file/tip/src/ > share/vm/classfile/vmSymbols.hpp#l664 ) and will use native instructions > where available. You can also test this yourself using jitwatch. There is > no native call overhead. > > The standard library does not currently include less accurate but faster > Math functions, maybe someone else can answer if that is something to be > considered. > > - Jonas Konrad > > On 11/09/2017 10:00 AM, Laurent Bourgès wrote: > >> Hi, >> >> The Marlin renderer (JEP265) uses few Math functions: sqrt, cbrt, acos... >> >> Could you check if the current JDK uses C2 intrinsics or libfdm (native / >> JNI overhead?) and tell me if such functions are already highly optimized >> in jdk9 or 10 ? >> >> Some people have implemented their own fast Math like Apache Commons Math >> or JaFaMa libraries that are 10x faster for acos / cbrt. >> >> I wonder if I should implement my own cbrt function (cubics) in pure java >> as I do not need the highest accuracy but SPEED. >> >> Would it sound possible to have a JDK FastMath public API (lots faster but >> less accurate?) >> >> Do you know if recent CPU (intel?) have dedicated instructions for such >> math operations ? >> Why not use it instead? >> Maybe that's part of the new Vectorization API (panama) ? >> >> Cheers, >> Laurent Bourges >> >>
