RFR(M): 8027422: assert(_gvn.type(obj)->higher_equal(tjp)) failed: cast_up is no longer needed

Vladimir Kozlov vladimir.kozlov at oracle.com
Thu Jan 16 01:11:21 PST 2014


On 1/16/14 1:05 AM, Roland Westrelin wrote:
>
> Thanks for reviewing this, Christian.
>
>> Seeing all these:
>>
>> true /* include_speculative */
>>
>> I wonder if we should add new methods for these.  It would make it easier to see the users of the speculative versions.
>
> A new meet_speculative() method?
> I’m ok with it. Vladimir, what do you think?

I was going to suggest it too but then you need additional methods for other methods: join(), higher_equal(), filter(). 
So I am fine with it if you do all of them.

Vladimir

>
> Roland.
>
>>
>> On Jan 14, 2014, at 7:25 AM, Vladimir Kozlov <vladimir.kozlov at oracle.com> wrote:
>>
>>> Looks good to me.
>>>
>>> On 1/14/14 1:13 AM, Roland Westrelin wrote:
>>>> http://cr.openjdk.java.net/~roland/8027422/webrev.02/
>>>>
>>>> I fixed the verification code at the end of Compile::remove_speculative_types(), used this format everywhere:
>>>> t->filter(_type, true /* include_speculative */);
>>>>
>>>> renamed NodeHash::check_speculative_types() to NodeHash::check_no_speculative_types(), added PhaseIterGVN::check_no_speculative_types() and now call it from the verification code of Compile::remove_speculative_types().
>>>>
>>>> Do I need more than 1 review for this?
>>>
>>> Yes, you need an other review for this change. Ask Chris or Igor.
>>>
>>> Thanks,
>>> Vladimir
>>>
>>>>
>>>> Roland.
>>>>
>>>>
>>>> On Jan 13, 2014, at 11:03 AM, Roland Westrelin <roland.westrelin at oracle.com> wrote:
>>>>
>>>>>> compile.cpp: new verification code (under ASSERT) at the end of remove_speculative_types() checks only the root node - nothing else is pushed on worklist. Also add comment to this new code.
>>>>>
>>>>> Thanks for catching that.
>>>>> Is:
>>>>> // Verify that after the IGVN is over no speculative type has resurfaced
>>>>> good as a comment?
>>>>>
>>>>>> Passing 'true' parameter is not very informative. You can use local variable:
>>>>>>
>>>>>> bool include_speculative = true;
>>>>>> t->filter(_type, include_speculative);
>>>>>>
>>>>>> An other way to make code more informative is to add a comment to parameter:
>>>>>>
>>>>>> t->filter(_type, true /* include_speculative */);
>>>>>>
>>>>>> Either way is fine.
>>>>>
>>>>> Will do one of these.
>>>>>
>>>>> Thanks,
>>>>> Roland.
>>>>>
>>>>>>
>>>>>> Thanks,
>>>>>> Vladimir
>>>>>>
>>>>>> On 1/10/14 1:46 AM, Roland Westrelin wrote:
>>>>>>> Hi Vladimir,
>>>>>>>
>>>>>>> Here is a new webrev for this:
>>>>>>> http://cr.openjdk.java.net/~roland/8027422/webrev.01/
>>>>>>>
>>>>>>> I fixed the issues you mentioned in your review.
>>>>>>> I added a call to remove_speculative() to the ConNode constructor. When a node becomes constant, its speculative part can be not null. The IGVN doesn’t kill ConNodes so without a call to remove_speculative() a ConNode with a speculative part can sneak past the call to Compile::remove_speculative_types().
>>>>>>> I also added a verification method:
>>>>>>> NodeHash::check_speculative_types()
>>>>>>> to check that no TypeNode with a speculative type is still in the IGVN hash table after Compile::remove_speculative_types()
>>>>>>>
>>>>>>> Roland.
>>>>>>>
>>>>>>> On Nov 19, 2013, at 8:49 PM, Vladimir Kozlov <vladimir.kozlov at oracle.com> wrote:
>>>>>>>
>>>>>>>> On 11/19/13 11:45 AM, Roland Westrelin wrote:
>>>>>>>>> Thanks for reviewing this, Vladimir.
>>>>>>>>>
>>>>>>>>> On Nov 19, 2013, at 1:34 AM, Vladimir Kozlov <vladimir.kozlov at oracle.com> wrote:
>>>>>>>>>
>>>>>>>>>> Next 2 places in type.cpp pass 'true' to meet() unconditionally:
>>>>>>>>>>
>>>>>>>>>> 1929     return TypeAry::make(_elem->meet(a->_elem, true),
>>>>>>>>>>
>>>>>>>>>> 3812     const TypeAry *tary = _ary->meet(tap->_ary, true)->is_ary();
>>>>>>>>>>
>>>>>>>>>> Should TypeAryPtr::remove_speculative() also clean _speculative in element's type?
>>>>>>>>>
>>>>>>>>> You’re right. It probably should.
>>>>>>>>> So I need to add a remove_speculative() method to TypeAry. Then the 2 places where true is passed to meet() for TypeAry don’t matter anymore because remove_speculative() is called from meet() and remove_speculative now has an effect on TypeAry, right?
>>>>>>>>
>>>>>>>> Right, passing 'true' will work in all cases then.
>>>>>>>>
>>>>>>>> Thanks,
>>>>>>>> Vladimir
>>>>>>>>
>>>>>>>>>
>>>>>>>>>> Could you make printing code with 'this_t' aligned again in Type::meet()?
>>>>>>>>>
>>>>>>>>> Sure.
>>>>>>>>>
>>>>>>>>> Roland.
>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> thanks,
>>>>>>>>>> Vladimir
>>>>>>>>>>
>>>>>>>>>> On 11/18/13 1:15 PM, Roland Westrelin wrote:
>>>>>>>>>>> The root of the problem is that during the null check when the type of obj is improved in GraphKit::cast_not_null():
>>>>>>>>>>> const Type *t_not_null = t->join(TypePtr::NOTNULL, true);
>>>>>>>>>>> The join with TypePtr::NOTNULL is not applied to the speculative part. In fact, no meet between a TypeOopPtr and a TypePtr modifies the speculative part. One way to fix it would be to apply the meet with a TypePtr to the speculative part as well as the standard part of the type which I tried: then we need to move the _speculative field up in TypePtr and modify all operations on TypePtr to operate on _speculative so that the type system remains symmetric.
>>>>>>>>>>> In many places where we mix a TypePtr with a TypeOopPtr we actually don’t care about the speculative part. I changed the following operations on Type:
>>>>>>>>>>> higher_equal()
>>>>>>>>>>> meet()
>>>>>>>>>>> join()
>>>>>>>>>>> filter()
>>>>>>>>>>> so that by default they don’t return a result that include the speculative part of the type. Where we need the speculative part of the type, we have to explicitly request it.
>>>>>>>>>>>
>>>>>>>>>>> I also fixed a problem with Type nodes with a _type of TypeNarrowOop that wouldn’t drop the speculative part of the type during Compile::remove_speculative_types().
>>>>>>>>>>> I included small clean ups that Mikael suggested privately (dropped the duplicate check for res->isa_oopptr() in TypeOopPtr::meet, make remove_speculative not go through the exercise of creating a new type if speculative is NULL).
>>>>>>>>>>>
>>>>>>>>>>> http://cr.openjdk.java.net/~roland/8027422/webrev.00/
>>>>>>>>>>>
>>>>>>>>>>> Roland.
>>>>>>>>>>>
>>>>>>>>>
>>>>>>>
>>>>>
>>>>
>>
>


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