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

[Roland Westrelin]

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.