replacing nodes with DeoptimizeNodes

[Tom Rodriguez]

On Mar 6, 2014, at 12:21 PM, Deneau, Tom <tom.deneau at amd.com> wrote:

> OK, and if I get an error like
>  lowering of NodeA produced lowerable NodeB that should have been
>  recursively lowered as it introduces these new nodes: [171|Deopt]
> 
> does that mean I have to write my own lowering for NodeA which as part of that also lowers the replacement nodeB?

Generally any lowering phase is required to finish in a single pass, so if you’re lowering is doing anything tricky that introduces Lowerable nodes than you need to manually lower them, usually by running your own LoweringPhase.  When are you getting this message?  MacroNodes do this for instance.

Is this happening as a result of your conversion of a node into a Deopt node?  Are you trying to do that during lowering?

tom

> 
> -- Tom
> 
>> -----Original Message-----
>> From: gilwooden at gmail.com [mailto:gilwooden at gmail.com] On Behalf Of
>> Gilles Duboscq
>> Sent: Wednesday, March 05, 2014 4:29 AM
>> To: Doug Simon
>> Cc: Deneau, Tom; graal-dev at openjdk.java.net
>> Subject: Re: replacing nodes with DeoptimizeNodes
>> 
>> On Wed, Mar 5, 2014 at 11:18 AM, Doug Simon <doug.simon at oracle.com>
>> wrote:
>>> 
>>> On Mar 5, 2014, at 1:27 AM, Deneau, Tom <tom.deneau at amd.com> wrote:
>>> 
>>>> Let's say there is some random graal node that you choose not to
>> implement so you want it to be replaced by a DeoptimizeNode.  How does
>> one do that if the original node is not a terminal node, ie, it has
>> usages?
>>> 
>>> The subgraph rooted at that node has to be removed (probably through
>> use of
>> com.oracle.graal.nodes.util.GraphUtil.killWithUnusedFloatingInputs(Node)
>> ).
>> 
>> Rather GraphUtil.killCFG(Node).
>> As an example, you can look at CanonicalizerPhase.performReplacement
>> (around line 297):
>>  //case 7
>>  fixed.predecessor().replaceFirstSuccessor(fixed, canonical);
>>  GraphUtil.killCFG(fixed);
>> 
>> even better would be:
>>  fixed.replaceAtPredecessor(canonical);
>>  GraphUtil.killCFG(fixed);
>> 
>> where in you case fixed is the node you want to replace and canonical is
>> the DeoptimizeNode.
>> 
>>> 
>>> -Doug
>