RFR(M): 8031754: Type speculation should favor profile data from outermost inlined method

[Vladimir Kozlov]

I think it is good.

Can you add "Use" to flag name: UseInlineDepthForSpeculativeTypes? It is 
more clear this way.

Thanks,
Vladimir

On 2/10/14 3:40 PM, Roland Westrelin wrote:
> Here is a new webrev:
>
> http://cr.openjdk.java.net/~roland/8031754/webrev.01/
>
> As suggested by Vladimir, I use a positive value for InlineDepthBottom and MAX for the meet of two depths. I also added asserts in remove_speculative. Whether this is used or not is under a command line option. There was also a missing argument to a call to TypeAryPtr::make() that went unnoticed because of default arguments.
>
> Roland.
>
>
> On Feb 6, 2014, at 7:29 PM, Vladimir Kozlov <vladimir.kozlov at oracle.com> wrote:
>
>> On 2/6/14 10:13 AM, Roland Westrelin wrote:
>>>>> Hi Vladimir,
>>>>>
>>>>>>>> In general I am comfortable to have inline_depth as additional type's attribute. But only for speculative types when it make sense.
>>>>>>>>
>>>>>>>> So why you keep _inline_depth in remove_speculative()?
>>>>>>>
>>>>>>> Because it’s never used in practice with non speculative types (it should always be InlineDepthBottom for a non speculative type). The only place where it changes the behavior of compilation is in GraphKit::record_profile_for_speculation() where it’s used only for speculative types. Anyway, I can reset it to InlineDepthBottom in remove_speculative() if you like.
>>>>>>
>>>>>> Yes, please, set to InlineDepthBottom. It will be consistent with types without speculative types.
>>>>>
>>>>> Actually, that’s not possible. Because then, that code:
>>>>>
>>>>> 2589     if (res_oopptr->remove_speculative() == res_oopptr->speculative()) {
>>>>> 2590       return res_oopptr->remove_speculative();
>>>>>
>>>>> in TypeOopPtr::xmeet()
>>>>>
>>>>> doesn’t trigger if res_oopptr has an inline depth of InlineDepthTop. remove_speculative() transforms it to InlineDepthBottom. And the type system is no longer symmetric.
>>>>
>>>> Do you know why it is top? The default value is InlineDepthBottom, how it is converted to top?
>>>
>>> It’s top because it’s a join and for a join the dual of the _inline_depth is used.
>>
>> Sorry, I misunderstood the code in remove_speculative(). I thought you replacing type's _inline_depth with one from speculative type but you simple preserving original _inline_depth of this type. The original code you had is good.
>>
>> Thanks,
>> Vladimir
>>
>>>
>>> Roland.
>>>
>>>>
>>>>>
>>>>> Instead shouldn’t I assert in remove_speculative() that if _speculative is non NULL then _inline_depth is InlineDepthTop or InlineDepthBottom?
>>>>
>>>> To have assert is good but we need to understand why in such case inline_depth could be top.
>>>>
>>>> Thanks,
>>>> Vladimir
>>>>
>>>>>
>>>>> Roland.
>