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

[Vladimir Kozlov]

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.

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.

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.
>>>>>
>>>
>