Request for review (L): 7071653: JSR 292: call site change notification should be pushed not pulled

[Charles Oliver Nutter]

I concur! I can't wait to see the new asm with recent fixes!

- Charlie (mobile)

On Aug 5, 2011, at 12:19, Rémi Forax <forax at univ-mlv.fr> wrote:

> Cool :)
> 
> Rémi
> 
> On 08/05/2011 03:32 PM, Christian Thalinger wrote:
>> http://cr.openjdk.java.net/~twisti/7071653
>> 
>> 7071653: JSR 292: call site change notification should be pushed not pulled
>> Reviewed-by:
>> 
>> Currently every speculatively inlined method handle call site has a
>> guard that compares the current target of the CallSite object to the
>> inlined one.  This per-invocation overhead can be removed if the
>> notification is changed from pulled to pushed (i.e. deoptimization).
>> 
>> I had to change the logic in TemplateTable::patch_bytecode to skip
>> bytecode quickening for putfield instructions when the put_code
>> written to the constant pool cache is zero.  This is required so that
>> every execution of a putfield to CallSite.target calls out to
>> InterpreterRuntime::resolve_get_put to do the deoptimization of
>> depending compiled methods.
>> 
>> I also had to change the dependency machinery to understand other
>> dependencies than class hierarchy ones.  DepChange got the super-type
>> of two new dependencies, KlassDepChange and CallSiteDepChange.
>> 
>> Tested with JRuby tests and benchmarks, hand-written testcases, JDK
>> tests and vm.mlvm tests.
>> 
>> Here is the speedup for the JRuby fib benchmark (first is JDK 7 b147,
>> second with 7071653).  Since the CallSite targets don't change during
>> the runtime of this benchmark we can see the performance benefit of
>> eliminating the guard:
>> 
>> $ jruby --server bench/bench_fib_recursive.rb 5 35
>>   0.883000   0.000000   0.883000 (  0.854000)
>>   0.715000   0.000000   0.715000 (  0.715000)
>>   0.712000   0.000000   0.712000 (  0.712000)
>>   0.713000   0.000000   0.713000 (  0.713000)
>>   0.713000   0.000000   0.713000 (  0.712000)
>> 
>> $ jruby --server bench/bench_fib_recursive.rb 5 35
>>   0.772000   0.000000   0.772000 (  0.742000)
>>   0.624000   0.000000   0.624000 (  0.624000)
>>   0.621000   0.000000   0.621000 (  0.621000)
>>   0.622000   0.000000   0.622000 (  0.622000)
>>   0.622000   0.000000   0.622000 (  0.621000)
>> 
>