Invokedynamic and recursive method call

[Marcus Lagergren]

Remi, I tried to reproduce your problem with jdk9 b44. It runs decently fast. When did it start to regress?

Regards
Marcus

> On 30 Dec 2014, at 20:48, Remi Forax <forax at 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
> 
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