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

[Vladimir Kozlov]

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.
>>>
>