Request for reviews (S): 6832293: JIT compiler got wrong result in type checking with -server

[Vladimir Kozlov]

Tom,

With this you will have the same problem with 2- multi- dimensional arrays
which I try to avoid with my changes. But I agree, may be element klasses
should be used only for interface and subtype checks.

On other hand why we are not using p0->meet(p1) == p0 || == p1?

Vladimir


Tom Rodriguez wrote:
> That doesn't seem quite right to me or maybe I just don't like the way 
> it's phrased.  The rules for subtyping for arrays are different than 
> instances, so walking up the classes would change the subtype test.  It 
> also creates in consistency between klass and xklass.  What about this:
> 
> diff --git a/src/share/vm/opto/subnode.cpp b/src/share/vm/opto/subnode.cpp
> --- a/src/share/vm/opto/subnode.cpp
> +++ b/src/share/vm/opto/subnode.cpp
> @@ -639,8 +639,11 @@ const Type *CmpPNode::sub( const Type *t
>      int kps = (p0->isa_klassptr()?1:0) + (p1->isa_klassptr()?1:0);
>      if (klass0 && klass1 &&
>          kps != 1 &&             // both or neither are klass pointers
> -        klass0->is_loaded() && !klass0->is_interface() && // do not 
> trust interfaces
> -        klass1->is_loaded() && !klass1->is_interface()) {
> +        // do not trust interfaces
> +        klass0->is_loaded() && !klass0->is_interface() &&
> +        (!klass0->is_obj_array_klass() || 
> !klass0->as_obj_array_klass()->base_element_klass()->is_interface()) &&
> +        klass1->is_loaded() && !klass1->is_interface() &&
> +        (!klass1->is_obj_array_klass() || 
> !klass1->as_obj_array_klass()->base_element_klass()->is_interface())) {
>        bool unrelated_classes = false;
>        // See if neither subclasses the other, or if the class on top
>        // is precise.  In either of these cases, the compare is known
> 
> tom
> 
> On May 8, 2009, at 1:12 PM, Vladimir Kozlov wrote:
> 
>> http://cr.openjdk.java.net/~kvn/6832293/webrev.00
>>
>> Fixed 6832293: JIT compiler got wrong result in type checking with 
>> -server
>>
>> Problem:
>> The code in CmpPNode::sub is broken for arrays of interface types.
>>
>> Solution:
>> In CmpPNode::sub compare klasses of obj arrays elements..
>>
>> Reviewed by:
>>
>> Fix verified (y/n): y, modified (for jdk7) bug's test
>>
>> Other testing:
>> JPRT
>>
>