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

[Roland Westrelin]

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?

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.
>>>>>>>>>> 
>>>>>>>> 
>>>>>> 
>>>> 
>>> 
>