Hi, On 05/01/15 18:59, Zoltan Sziladi wrote:
> This discussion was a long time ago, I was just reading through it to check > again what was the last state of the discussion about the String.indexOf. > There is one part which I still do not understand, hopefully someone could > shed some light on it. A few emails ago Martin mentioned > > "Hotspot seems to have some intrinsification of String.indexOf, which > confuses me. > Hotspot seems the right place to provide more optimizations for this, since > there has been a fair amount of work creating high-performance low-level > implementations of this idea in C." > > Then Ivan asked what that actually meant, whether hotspot actually replaced > the jdk implementation with a low level optimized C implementation, but I > never saw an answer to that. You can have a look at an implementation of MacroAssembler::string_indexof in http://hg.openjdk.java.net/jdk9/jdk9/hotspot/file/b6b89b8f8531/src/cpu/x86/vm/macroAssembler_x86.cpp > Can someone please explain this? If we somehow found an algorithm that beat > the naive implementation in the average case, would it be possible to just > implement it in the JDK? No, because HotSpot would ignore it. Any speed improvements have to be done in the architecture-dependent files. Andrew.
