7u40 is when the native invoke dynamic implementation was replaced with Lambda Forms :-/
/M > On 07 Jan 2015, at 17:13, Remi Forax <fo...@univ-mlv.fr> wrote: > > > On 01/07/2015 10:43 AM, Marcus Lagergren wrote: >> Remi, I tried to reproduce your problem with jdk9 b44. It runs decently fast. > > yes, nashorn is fast enough but it can be faster if the JIT was not doing > something stupid. > > When the VM inline fibo, because fibo is recursive, the recursive call is > inlined only once, > so the call at depth=2 can not be inlined but should be a classical direct > call. > > But if fibo is called through an invokedynamic, instead of emitting a direct > call to fibo, > the JIT generates a code that push the method handle on stack and execute it > like if the metod handle was not constant > (the method handle is constant because the call at depth=1 is inlined !). > >> When did it start to regress? > > jdk7u40, i believe. > > I've created a jar containing some handwritten bytecodes with no dependency > to reproduce the issue easily: > https://github.com/forax/vmboiler/blob/master/test7/fibo7.jar > <https://github.com/forax/vmboiler/blob/master/test7/fibo7.jar> > > [forax@localhost test7]$ time /usr/jdk/jdk1.9.0/bin/java -cp fibo7.jar > FiboSample > 1836311903 > > real 0m6.653s > user 0m6.729s > sys 0m0.019s > [forax@localhost test7]$ time /usr/jdk/jdk1.8.0_25/bin/java -cp fibo7.jar > FiboSample > 1836311903 > > real 0m6.572s > user 0m6.591s > sys 0m0.019s > [forax@localhost test7]$ time /usr/jdk/jdk1.7.0_71/bin/java -cp fibo7.jar > FiboSample > 1836311903 > > real 0m6.373s > user 0m6.396s > sys 0m0.016s > [forax@localhost test7]$ time /usr/jdk/jdk1.7.0_25/bin/java -cp fibo7.jar > FiboSample > 1836311903 > > real 0m4.847s > user 0m4.832s > sys 0m0.019s > > as you can see, it was faster with a JDK before jdk7u40. > >> >> Regards >> Marcus > > cheers, > Rémi > >> >>> On 30 Dec 2014, at 20:48, Remi Forax <fo...@univ-mlv.fr> wrote: >>> >>> Hi guys, >>> I've found a bug in the interaction between the lambda form and inlining >>> algorithm, >>> basically if the inlining heuristic bailout because the method is recursive >>> and already inlined once, >>> instead to emit a code to do a direct call, it revert to do call to >>> linkStatic with the method >>> as MemberName. >>> >>> I think it's a regression because before the introduction of lambda forms, >>> I'm pretty sure that the JIT was emitting a direct call. >>> >>> Step to reproduce with nashorn, run this JavaScript code >>> function fibo(n) { >>> return (n < 2)? 1: fibo(n - 1) + fibo(n - 2) >>> } >>> >>> print(fibo(45)) >>> >>> like this: >>> /usr/jdk/jdk1.9.0/bin/jjs -J-XX:+UnlockDiagnosticVMOptions >>> -J-XX:+PrintAssembly fibo.js > log.txt >>> >>> look for a method 'fibo' from the tail of the log, you will find something >>> like this: >>> >>> 0x00007f97e4b4743f: mov $0x76d08f770,%r8 ; {oop(a >>> 'java/lang/invoke/MemberName' = {method} {0x00007f97dcff8e40} 'fibo' >>> '(Ljdk/nashorn/internal/runtime/ScriptFunction;Ljava/lang/Object;I)I' in >>> 'jdk/nashorn/internal/scripts/Script$Recompilation$2$fibo')} >>> 0x00007f97e4b47449: xchg %ax,%ax >>> 0x00007f97e4b4744b: callq 0x00007f97dd0446e0 >>> >>> I hope this can be fixed. My demonstration that I can have fibo written >>> with a dynamic language >>> that run as fast as written in Java doesn't work anymore :( >>> >>> cheers, >>> Rémi >>> >>> _______________________________________________ >>> mlvm-dev mailing list >>> mlvm-dev@openjdk.java.net >>> http://mail.openjdk.java.net/mailman/listinfo/mlvm-dev >> _______________________________________________ >> mlvm-dev mailing list >> mlvm-dev@openjdk.java.net >> http://mail.openjdk.java.net/mailman/listinfo/mlvm-dev > > _______________________________________________ > mlvm-dev mailing list > mlvm-dev@openjdk.java.net <mailto:mlvm-dev@openjdk.java.net> > http://mail.openjdk.java.net/mailman/listinfo/mlvm-dev > <http://mail.openjdk.java.net/mailman/listinfo/mlvm-dev>
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