review (XS) for 6982533: Crash in ~StubRoutines::jbyte_fill with AggressiveOpts enabled

[Vladimir Kozlov]

Tom,

I am fine with your index explicit check, I only want an additional check for array ptr and your suggestion is good.

Your current changes look good.

Thanks,
Vladimir

Tom Rodriguez wrote:
> On Sep 7, 2010, at 10:49 AM, Vladimir Kozlov wrote:
> 
>> Looks good but could we also check (in assert?) that address type is array pointer?
> 
> I considered adding that as an early check but I wanted an explicit check that we found the index to confirm the shape of the address expression.  I could add an early weed out test:
> 
> --- a/src/share/vm/opto/loopTransform.cpp       Fri Sep 03 13:31:03 2010 -0700                                                                       
> +++ b/src/share/vm/opto/loopTransform.cpp       Tue Sep 07 11:04:07 2010 -0700                                                                       
> @@ -2417,6 +2417,8 @@ bool PhaseIdealLoop::match_fill_loop(Ide
>        Node* value = n->in(MemNode::ValueIn);                                                                                                         
>        if (!lpt->is_invariant(value)) {                                                                                                               
>          msg  = "variant store value";                                                                                                               
> +      } else if (!_igvn.type(n->in(MemNode::Address))->isa_aryptr()) {                                                                               
> +        msg = "not array address";                                                                                                                   
>        }                                                                                                                                             
>        store = n;                                                                                                                                     
>        store_value = value; 
> 
> tom
> 
>> Thanks,
>> Vladimir
>>
>> Tom Rodriguez wrote:
>>> http://cr.openjdk.java.net/~never/6982533
>>> 6982533: Crash in  ~StubRoutines::jbyte_fill with AggressiveOpts enabled
>>> Reviewed-by:
>>> The logic for matching a byte fill is missing a check for the use of
>>> the index.  It normally happens as part of the check for a shift
>>> expression but since a byte array doesn't have a shift the check is
>>> missed.  The fix is to make the index check explicit.  The reason it
>>> didn't always crash was because of differences in heap size caused by
>>> ergonomics.  With a 16m heap it crashes on any machine.  Tested with
>>> failing test case.
>>> src/share/vm/opto/loopTransform.cpp
>