ping ?
Rémi
On 12/30/2014 08:48 PM, Remi Forax 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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