Request for reviews (S): 6809798: SafePointScalarObject node placed into incorrect block during GCM

[Vladimir Kozlov]

I only saw asserts for SafePointScalarObjectNodes.
But patching control edge of pinned nodes before scheduling
affects all pinned nodes: safepoints, phis.
And I think this change is correct for all pinned nodes.

I actually was not able to catch the case were
safepoint has block projection control to see what
happened. In the bugs case it was scheduled correctly
even with current code. But it could be the case
when control was set differently for SFPT and SPSO nodes
during IGVN in IfNode::dominated_by() which I fixed by
SafePointScalarObjectNode::depends_only_on_test() const { return false; }

Thanks,
Vladimir

Tom Rodriguez wrote:
> Were SafePointScalarObjectNodes the only one affected by this or will 
> this change the schedule of other nodes?
> 
> tom
> 
> On Feb 26, 2009, at 10:15 AM, Vladimir Kozlov wrote:
> 
>> http://cr.openjdk.java.net/~kvn/6809798/webrev.00
>>
>> Fixed 6809798: SafePointScalarObject node placed into incorrect block 
>> during GCM
>>
>> Problem:
>> The main problem is that the control edge of a pinned node
>> could be replaced during schedule_early after the pinned
>> node scheduled into a block if the control node is a block
>> projection.
>> Also there were few places where the control edge of
>> a SafePointScalarObject node was not adjusted correctly.
>>
>> Solution:
>> Replace the control edge of a pinned node before scheduling.
>> Adjust the control edge of a SafePointScalarObject when needed.
>> Added few asserts to verify scheduling correctness for
>> pinned nodes and SafePointScalarObject node.
>>
>> Reviewed by:
>>
>> Fix verified (y/n): y
>>
>> Other testing:
>> JPRT, CTW (with -XX:+DoEscapeAnalysis)
>>
>