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

[Vladimir Kozlov]

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?

Could you make printing code with 'this_t' aligned again in Type::meet()?

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.
>