MaxRecursiveInlineLevel oddity

[Vladimir Kozlov]

6552561: MaxRecursiveInlineLevel flag doesn't operate correctly

Tom Rodriguez wrote:
> I believe there's actually a bug already filed about this.  It will certainly change the results of the inlining in rare cases but it seems reasonable to may it consistent.
> 
> tom
> 
> On Apr 28, 2011, at 6:38 AM, Christian Thalinger wrote:
> 
>> While looking at JRuby performance and thus assembly code I noticed an oddity with recursive inlining:
>>
>> $ java -XX:CICompilerCount=1 -XX:+PrintCompilation -XX:+PrintInlining -XX:MaxRecursiveInlineLevel=0 fib
>> VM option 'CICompilerCount=1'
>> VM option '+PrintCompilation'
>> VM option '+PrintInlining'
>> VM option 'MaxRecursiveInlineLevel=0'
>>    340    1             fib::fib (21 bytes)
>>                            @ 10   fib::fib (21 bytes)   inline (hot)
>>                              @ 10   fib::fib (21 bytes)   recursively inlining too deep
>>                              @ 16   fib::fib (21 bytes)   recursively inlining too deep
>>                            @ 16   fib::fib (21 bytes)   inline (hot)
>>                              @ 10   fib::fib (21 bytes)   recursively inlining too deep
>>                              @ 16   fib::fib (21 bytes)   recursively inlining too deep
>>    362    1 %           fib::main @ 2 (21 bytes)
>>                            @ 10   fib::fib (21 bytes)   inline (hot)
>>                              @ 10   fib::fib (21 bytes)   recursively inlining too deep
>>                              @ 16   fib::fib (21 bytes)   recursively inlining too deep
>>
>> It seems there is a "bug" in the logic in that it doesn't take the compiled method into account when counting the recursive inlining depth.  I expected when using MaxRecursiveInlineLevel=0 that there is no recursive inlining at all.
>>
>> The simple example above shows that it might be possible that there are performance jumps between the various compiled methods as the recursive inlining depth changes.
>>
>> I'd like to fix that (and I already have a fix that handles direct and indirect recursion) but the question is can we fix that given the possibility that it can change performance of applications?
>>
>> -- Christian
>