[13] RFR(XS):8226287: Make process_users_of_allocation handle gc barriers

[Nils Eliasson]

On 2019-06-26 15:42, Roland Westrelin wrote:
>> The loadbarrier is left hanging. Later in expand_loadbarrier_node we
>> crash when trying to remove a dead node  in
>> PhaseIterGVN::remove_globally_dead_node(Node*).
>>
>> Sometimes "assert(init->in(TypeFunc::Control) == _fallthroughcatchproj)"
>> in macro.cpp line~1006 catches the problem.
> Wouldn't there be a way to remove the init barrier anyway? Doesn't:
>
> _igvn.replace_node(ctrl_proj, init->in(TypeFunc::Control));
>
> always work?

_igvn.replace_node(ctrl_proj, init->in(TypeFunc::Control)) should always 
work.

I added the checks to be able to keep the 
"assert(init->in(TypeFunc::Control) == _fallthroughcatchproj, 
"allocation control projection");"

Mostly because it could be nice to catch any other malformed control 
flow here. And from the beginning I was a bit unsure if there where 
other code paths that assumes the 
alloc->proj->catch->catchproj->initialize pattern.

I can remove it if you want to. It definitely gets easier to read.


>
> Roland.